Sample records for vertical gradient freeze

  1. The use of magnetic fields in vertical Bridgman/Gradient Freeze-type crystal growth

    NASA Astrophysics Data System (ADS)

    Pätzold, Olf; Niemietz, Kathrin; Lantzsch, Ronny; Galindo, Vladimir; Grants, Ilmars; Bellmann, Martin; Gerbeth, Gunter

    2013-03-01

    This paper outlines advanced vertical Bridgman/Gradient Freeze techniques with flow control using magnetic fields developed for the growth of semiconductor crystals. Low-temperature flow modelling, as well as laboratory-scaled crystal growth under the influence of rotating, travelling, and static magnetic fields are presented. Experimental and numerical flow modelling demonstrate the potential of the magnetic fields to establish a well-defined flow for tailoring heat and mass transfer in the melt during growth. The results of the growth experiments are discussed with a focus on the influence of a rotating field on the segregation of dopants, the influence of a travelling field on the temperature field and thermal stresses, and the potential of rotating and static fields for a stabilization of the melt flow.

  2. Growth of benzil crystals by vertical dynamic gradient freeze technique in a transparent furnace

    NASA Astrophysics Data System (ADS)

    Lan, C. W.; Song, C. R.

    1997-09-01

    The vertical dynamic gradient freeze technique using a transparent furnace was applied to the growth of benzil single crystals. A flat-bottom ampoule with a <0001> seed was used for growth. During crystal growth, dynamic heating profiles were controlled through a computer, and the growth interface was recorded by a CCD camera. Computer simulation was also conducted, and the calculated convex interface and dynamic growth rate were consistent with the observed ones for various growth conditions. Conditions for growing single crystals were also determined, and they were mainly limited by constitutional supercooling. As the grown crystals were clear in appearance, their optical absorption spectra were insensitive to growth conditions and post-annealing.

  3. Investigation on the growth and characterization of 4-aminobenzophenone single crystal by the vertical dynamic gradient freeze technique

    NASA Astrophysics Data System (ADS)

    Prabhakaran, SP.; Ramesh Babu, R.; Sukumar, M.; Bhagavannarayana, G.; Ramamurthi, K.

    2014-03-01

    Growth of bulk single crystal of 4-Aminobenzophenone (4-ABP) from the vertical dynamic gradient freeze (VDGF) setup designed with eight zone furnace was investigated. The experimental parameters for the growth of 4-ABP single crystal with respect to the design of VDGF setup are discussed. The eight zones were used to generate multiple temperature gradients over the furnace, and video imaging system helped to capture the real time growth and solid-liquid interface. 4-ABP single crystal with the size of 18 mm diameter and 40 mm length was grown from this investigation. Structural and optical quality of grown crystal was examined by high resolution X-ray diffraction and UV-visible spectral analysis, respectively and the blue emission was also confirmed from the photoluminescence spectrum. Microhardness number of the crystal was estimated at different loads using Vicker's microhardness tester. The size and quality of single crystal grown from the present investigation are compared with the vertical Bridgman grown 4-ABP.

  4. Crystal Growth and Characterization of CdTe Grown by Vertical Gradient Freeze

    NASA Technical Reports Server (NTRS)

    Su, Ching-Hua; Lehoczky, S. L.; Raghothamachar, B.; Dudley, M.

    2007-01-01

    In this study, crystals of CdTe were grown from melts by the unseeded vertical gradient freeze method. The quality of grown crystal were studied by various characterization techniques including Synchrotron White Beam X-ray Topography (SWBXT), chemical analysis by glow discharge mass spectroscopy (GDMS), low temperature photoluminescence (PL), and Hall measurements. The SWBXT images from various angles show nearly strain-free grains, grains with inhomogeneous strains, as well as twinning nucleated in the shoulder region of the boule. The GDMS chemical analysis shows the contamination of Ga at a level of 3900 ppb, atomic. The low temperature PL measurement exhibits the characteristic emissions of a Ga-doped sample. The Hall measurements show a resistivity of 1 x l0(exp 7) ohm-cm at room temperature to 3 x 10(exp 9) ohm-cm at 78K with the respective hole and electron concentration of 1.7 x 10(exp 9) cm(exp -3) and 3.9 x 10(exp 7) cm(exp -3) at room temperature.

  5. Fluid flow analysis and vertical gradient freeze crystal growth in a travelling magnetic field

    NASA Astrophysics Data System (ADS)

    Lantzsch, R.; Grants, I.; Galindo, V.; Patzold, O.; Gerbeth, G.; Stelter, M.; Croll, A.

    2006-12-01

    In bulk crystal growth of semiconductors the concept of remote flow control by means of alternating magnetic fields has attracted considerable interest (see, e.g., te{1,2,3,4,5,6}). In this way the melt flow can be tailored for growth under optimised conditions to improve the crystal properties and/or the growth yield. A promising option is to apply an axially travelling magnetic wave to the melt (Travelling Magnetic Field - TMF). It introduces a mainly axial Lorentz force, which leads to meridional flow patterns. In recent numerical studies te{3}, te{6} the TMF has been recognised to be a versatile and efficient tool to control the heat and mass transport in the melt. For the Vertical Bridgman/Vertical Gradient Freeze (VB/VGF) growth, the beneficial effect of an adequately adjusted TMF-induced flow was clearly demonstrated in te{6} in terms of the reduction of thermal shear stress at the solid-liquid interface. In this paper, we present experimental and numerical results on the TMF driven convection in an isothermal model fluid as well as first VGF-TMF crystal growth experiments. The model investigations are focused on the transition from laminar to instationary flow conditions that should be avoided in crystal growth applications. The VGF experiments were aimed at growing Ga doped germanium single crystals under the influence of the travelling field in a newly developed VGF-TMF equipment. Figs 4, Refs 10.

  6. Brown bear sperm double freezing: Effect of elapsed time and use of PureSperm(®) gradient between freeze-thaw cycles.

    PubMed

    Alvarez-Rodríguez, Manuel; Alvarez, Mercedes; López-Urueña, Elena; Martínez-Rodriguez, Carmen; Borragan, Santiago; Anel-López, Luis; de Paz, Paulino; Anel, Luis

    2013-12-01

    The use of sexed spermatozoa has great potential to captive population management in endangered wildlife. The problem is that the sex-sorting facility is a long distance from the semen collection place and to overcome this difficulty two freeze-thaw cycles may be necessary. In this study, effects of refreezing on brown bear electroejaculated spermatozoa were analyzed. We carried out two experiments: (1) to assess the effects of the two freezing-thawing cycles on sperm quality and to analyze three different elapsed times between freezing-thawing cycles (30, 90 and 180 min), and (2) to analyze the use of PureSperm between freezing-thawing cycles to select a more motile and viable sperm subpopulation which better survived first freezing. The motility, viability and undamaged acrosomes were significantly reduced after the second thawing respect to first thawing into each elapsed time group, but the elapsed times did not significantly affect the viability and acrosome status although motility was damaged. Our results with the PureSperm gradient showed higher values of viability in freezability of select sample (pellet) respect to the rest of the groups and it also showed a significant decrease in the number of acrosome damaged. In summary, the double freezing of bear semen selected by gradient centrifugation is qualitatively efficient, and thus could be useful to carry out a sex-sorting of frozen-thawed bear spermatozoa before to send the cryopreserved sample to a biobank. Given the low recovery of spermatozoa after applying a selection gradient, further studies will be needed to increase the recovery rate without damaging of the cell quality. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. Semiconductor apparatus utilizing gradient freeze and liquid-solid techniques

    NASA Technical Reports Server (NTRS)

    Fleurial, Jean-Pierre (Inventor); Caillat, Thierry F. (Inventor); Borshchevsky, Alexander (Inventor)

    1998-01-01

    Transition metals of Group VIII (Co, Rh and Ir) have been prepared as semiconductor compounds with the general formula TSb.sub.3. The skutterudite-type crystal lattice structure of these semiconductor compounds and their enhanced thermoelectric properties results in semiconductor materials which may be used in the fabrication of thermoelectric elements to substantially improve the efficiency of the resulting thermoelectric device. Semiconductor materials having the desired skutterudite-type crystal lattice structure may be prepared in accordance with the present invention by using vertical gradient freezing techniques and/or liquid phase sintering techniques. Measurements of electrical and thermal transport properties of selected semiconductor materials prepared in accordance with the present invention, demonstrated high Hall mobilities (up to 1200 cm.sup.2.V.sup.-1.s.sup.-1) and good Seebeck coefficients (up to 150 .mu.VK.sup.-1 between 300.degree. C. and 700.degree. C.). Optimizing the transport properties of semiconductor materials prepared from elemental mixtures Co, Rh, Ir and Sb resulted in a substantial increase in the thermoelectric figure of merit (ZT) at temperatures as high as 400.degree. C. for thermoelectric elements fabricated from such semiconductor materials.

  8. How important are internal temperature gradients in french straws during freezing of bovine sperm in nitrogen vapor?

    PubMed

    Santos, M V; Sansinena, M; Zaritzky, N; Chirife, J

    2013-01-01

    The subject of present work was to predict internal temperature gradients developed during freezing of bovine sperm diluted in extender, packaged in 0.5 ml French plastic straws and suspended in static liquid nitrogen vapor at -100 degree C. For this purpose, a mathematical heat transfer model previously developed to predict freezing times (phase change was considered) of semen/extender packaged in straw was extended to predict internal temperature gradients during the cooling/freezing process. Results showed maximum temperature differences between the centre and the periphery of semen/extender "liquid" column was 1.5 degree C for an external heat transfer coefficient, h = 15 W per (m(2) K), and only 0.5 degree C for h = 5 W per (m(2) K). It is concluded that if a thermocouple wire were inserted in a 0.5 ml plastic straw to monitor the freezing process in nitrogen vapor, its radial position would have little importance since expected internal gradients may be safely neglected. This finding facilitates the interpretation of freezing rates in 0.5 ml plastic straws immersed in nitrogen vapor over liquid nitrogen, a widely used method for cryopreservation of bovine spermatozoa.

  9. Retained functional integrity of bull spermatozoa after double freezing and thawing using PureSperm density gradient centrifugation.

    PubMed

    Maxwell, W M C; Parrilla, I; Caballero, I; Garcia, E; Roca, J; Martinez, E A; Vazquez, J M; Rath, D

    2007-10-01

    The main aim of this study was to compare the motility and functional integrity of bull spermatozoa after single and double freezing and thawing. The viability and morphological integrity of spermatozoa selected by PureSperm density gradient centrifugation after cryopreservation of bovine semen in two commercial extenders (Experiment 1) and the function of bull spermatozoa before and after a second freezing and thawing assisted by PureSperm selection (Experiment 2) were examined. On average, 35.8 +/- 12.1% of sperm loaded onto the PureSperm density gradient were recovered after centrifugation. In Experiment 1, post-thaw motility and acrosome integrity were higher for spermatozoa frozen in Tris-egg yolk extender than in AndroMed, whether the assessments were made immediately after thawing [80.4 +/- 12.7 vs 47.6 +/- 19.0% motile and 78.8 +/- 8.3 vs 50.1 +/- 19.5% normal apical ridge (NAR), p < 0.05] or after preparation on the gradient (83.3 +/- 8.6 vs 69.4 +/- 15.9% motile and 89.5 +/- 7.2 vs 69.1 +/- 11.4% NAR, p < 0.05). For semen frozen in Tris-egg yolk extender, selection on the PureSperm gradient did not influence total motility but significantly improved the proportion of acrosome-intact spermatozoa. After the gradient, both the total motility and percentage of normal acrosomes increased for spermatozoa frozen in AndroMed (Minitüb Tiefenbach, Germany). In Experiment 2, there was no difference in sperm motility after the first and second freeze-thawing (82.9 +/- 12.7 vs 68.8 +/- 18.7%). However, the proportion of acrosome-intact spermatozoa was significantly improved by selection through the PureSperm gradient, whether measured by phase contrast microscopy (78.9 +/- 9.7 vs 90.4 +/- 4.0% NAR, p < 0.05) or flow cytometry (53.4 +/- 11.7 vs 76.3 +/- 6.0% viable acrosome-intact spermatozoa, p < 0.001). The improvement in the percentage of spermatozoa with normal acrosomes was maintained after resuspension in the cooling extender and cooling to 4 degrees C (88

  10. Using absolute gravimeter data to determine vertical gravity gradients

    USGS Publications Warehouse

    Robertson, D.S.

    2001-01-01

    The position versus time data from a free-fall absolute gravimeter can be used to estimate the vertical gravity gradient in addition to the gravity value itself. Hipkin has reported success in estimating the vertical gradient value using a data set of unusually good quality. This paper explores techniques that may be applicable to a broader class of data that may be contaminated with "system response" errors of larger magnitude than were evident in the data used by Hipkin. This system response function is usually modelled as a sum of exponentially decaying sinusoidal components. The technique employed here involves combining the x0, v0 and g parameters from all the drops made during a site occupation into a single least-squares solution, and including the value of the vertical gradient and the coefficients of system response function in the same solution. The resulting non-linear equations must be solved iteratively and convergence presents some difficulties. Sparse matrix techniques are used to make the least-squares problem computationally tractable.

  11. A wet/wet differential pressure sensor for measuring vertical hydraulic gradient.

    PubMed

    Fritz, Brad G; Mackley, Rob D

    2010-01-01

    Vertical hydraulic gradient is commonly measured in rivers, lakes, and streams for studies of groundwater-surface water interaction. While a number of methods with subtle differences have been applied, these methods can generally be separated into two categories; measuring surface water elevation and pressure in the subsurface separately or making direct measurements of the head difference with a manometer. Making separate head measurements allows for the use of electronic pressure sensors, providing large datasets that are particularly useful when the vertical hydraulic gradient fluctuates over time. On the other hand, using a manometer-based method provides an easier and more rapid measurement with a simpler computation to calculate the vertical hydraulic gradient. In this study, we evaluated a wet/wet differential pressure sensor for use in measuring vertical hydraulic gradient. This approach combines the advantage of high-temporal frequency measurements obtained with instrumented piezometers with the simplicity and reduced potential for human-induced error obtained with a manometer board method. Our results showed that the wet/wet differential pressure sensor provided results comparable to more traditional methods, making it an acceptable method for future use.

  12. Direct mapping of the temperature and velocity gradients in discs. Imaging the vertical CO snow line around IM Lupi

    NASA Astrophysics Data System (ADS)

    Pinte, C.; Ménard, F.; Duchêne, G.; Hill, T.; Dent, W. R. F.; Woitke, P.; Maret, S.; van der Plas, G.; Hales, A.; Kamp, I.; Thi, W. F.; de Gregorio-Monsalvo, I.; Rab, C.; Quanz, S. P.; Avenhaus, H.; Carmona, A.; Casassus, S.

    2018-01-01

    Accurate measurements of the physical structure of protoplanetary discs are critical inputs for planet formation models. These constraints are traditionally established via complex modelling of continuum and line observations. Instead, we present an empirical framework to locate the CO isotopologue emitting surfaces from high spectral and spatial resolution ALMA observations. We apply this framework to the disc surrounding IM Lupi, where we report the first direct, i.e. model independent, measurements of the radial and vertical gradients of temperature and velocity in a protoplanetary disc. The measured disc structure is consistent with an irradiated self-similar disc structure, where the temperature increases and the velocity decreases towards the disc surface. We also directly map the vertical CO snow line, which is located at about one gas scale height at radii between 150 and 300 au, with a CO freeze-out temperature of 21 ± 2 K. In the outer disc (>300 au), where the gas surface density transitions from a power law to an exponential taper, the velocity rotation field becomes significantly sub-Keplerian, in agreement with the expected steeper pressure gradient. The sub-Keplerian velocities should result in a very efficient inward migration of large dust grains, explaining the lack of millimetre continuum emission outside of 300 au. The sub-Keplerian motions may also be the signature of the base of an externally irradiated photo-evaporative wind. In the same outer region, the measured CO temperature above the snow line decreases to ≈15 K because of the reduced gas density, which can result in a lower CO freeze-out temperature, photo-desorption, or deviations from local thermodynamic equilibrium.

  13. Convective flows in enclosures with vertical temperature or concentration gradients

    NASA Technical Reports Server (NTRS)

    Wang, L. W.; Chai, A. T.; Sun, D. J.

    1988-01-01

    The transport process in the fluid phase during the growth of a crystal has a profound influence on the structure and quality of the solid phase. In vertical growth techniques the fluid phase is often subjected to vertical temperature and concentration gradients. The main objective is to obtain more experimental data on convective flows in enclosures with vertical temperature or concentration gradients. Among actual crystal systems the parameters vary widely. The parametric ranges studied for mass transfer are mainly dictated by the electrochemical system employed to impose concentration gradients. Temperature or concentration difference are maintained between two horizontal end walls. The other walls are kept insulated. Experimental measurements and observations were made of the heat transfer or mass transfer, flow patterns, and the mean and fluctuating temperature distribution. The method used to visualize the flow pattern in the thermal cases is an electrochemical pH-indicator method. Laser shadowgraphs are employed to visualize flow patterns in the solutal cases.

  14. Convective flows in enclosures with vertical temperature or concentration gradients

    NASA Technical Reports Server (NTRS)

    Wang, L. W.; Chai, A. T.; Sun, D. J.

    1989-01-01

    The transport process in the fluid phase during the growth of a crystal has a profound influence on the structure and quality of the solid phase. In vertical growth techniques the fluid phase is often subjected to vertical temperature and concentration gradients. The main objective is to obtain more experimental data on convective flows in enclosures with vertical temperature or concentration gradients. Among actual crystal systems the parameters vary widely. The parametric ranges studied for mass transfer are mainly dictated by the electrochemical system employed to impose concentration gradients. Temperature or concentration difference are maintained between two horizontal end walls. The other walls are kept insulated. Experimental measurements and observations were made of the heat transfer or mass transfer, flow patterns, and the mean and fluctuating temperature distribution. The method used to visualize the flow pattern in the thermal cases is an electrochemical pH-indicator method. Laser shadowgraphs are employed to visualize flow patterns in the solutal cases.

  15. Freeze drying apparatus

    DOEpatents

    Coppa, Nicholas V.; Stewart, Paul; Renzi, Ernesto

    2001-01-01

    The present invention provides methods and apparatus for freeze drying in which a solution, which can be a radioactive salt dissolved within an acid, is frozen into a solid on vertical plates provided within a freeze drying chamber. The solid is sublimated into vapor and condensed in a cold condenser positioned above the freeze drying chamber and connected thereto by a conduit. The vertical positioning of the cold condenser relative to the freeze dryer helps to help prevent substances such as radioactive materials separated from the solution from contaminating the cold condenser. Additionally, the system can be charged with an inert gas to produce a down rush of gas into the freeze drying chamber to also help prevent such substances from contaminating the cold condenser.

  16. Freeze drying method

    DOEpatents

    Coppa, Nicholas V.; Stewart, Paul; Renzi, Ernesto

    1999-01-01

    The present invention provides methods and apparatus for freeze drying in which a solution, which can be a radioactive salt dissolved within an acid, is frozen into a solid on vertical plates provided within a freeze drying chamber. The solid is sublimated into vapor and condensed in a cold condenser positioned above the freeze drying chamber and connected thereto by a conduit. The vertical positioning of the cold condenser relative to the freeze dryer helps to help prevent substances such as radioactive materials separated from the solution from contaminating the cold condenser. Additionally, the system can be charged with an inert gas to produce a down rush of gas into the freeze drying chamber to also help prevent such substances from contaminating the cold condenser.

  17. Property Improvement in CZT via Modeling and Processing Innovations . Te-particles in vertical gradient freeze CZT: Size and Spatial Distributions and Constitutional Supercooling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Henager, Charles H.; Alvine, Kyle J.; Bliss, Mary

    2014-10-01

    A section of a vertical gradient freeze CZT boule approximately 2100-mm 3 with a planar area of 300-mm 2 was prepared and examined using transmitted IR microscopy at various magnifications to determine the three-dimensional spatial and size distributions of Te-particles over large longitudinal and radial length scales. The boule section was approximately 50-mm wide by 60-mm in length by 7-mm thick and was doubly polished for TIR work. Te-particles were imaged through the thickness using extended focal imaging to locate the particles in thickness planes spaced 15-µm apart and then in plane of the image using xy-coordinates of the particlemore » center of mass so that a true three dimensional particle map was assembled for a 1-mm by 45-mm longitudinal strip and for a 1-mm by 50-mm radial strip. Te-particle density distributions were determined as a function of longitudinal and radial positions in these strips, and treating the particles as vertices of a network created a 3D image of the particle spatial distribution. Te-particles exhibited a multi-modal log-normal size density distribution that indicated a slight preference for increasing size with longitudinal growth time, while showing a pronounced cellular network structure throughout the boule that can be correlated to dislocation network sizes in CZT. Higher magnification images revealed a typical Rayleigh-instability pearl string morphology with large and small satellite droplets. This study includes solidification experiments in small crucibles of 30:70 mixtures of Cd:Te to reduce the melting point below 1273 K (1000°C). These solidification experiments were performed over a wide range of cooling rates and clearly demonstrated a growth instability with Te-particle capture that is suggested to be responsible for one of the peaks in the size distribution using size discrimination visualization. The results are discussed with regard to a manifold Te-particle genesis history as 1) Te-particle direct capture

  18. Airship stresses due to vertical velocity gradients and atmospheric turbulence

    NASA Technical Reports Server (NTRS)

    Sheldon, D.

    1975-01-01

    Munk's potential flow method is used to calculate the resultant moment experienced by an ellipsoidal airship. This method is first used to calculate the moment arising from basic maneuvers considered by early designers, and then expended to calculate the moment arising from vertical velocity gradients and atmospheric turbulence. This resultant moment must be neutralized by the transverse force of the fins. The results show that vertical velocity gradients at a height of 6000 feet in thunderstorms produce a resultant moment approximately three to four times greater than the moment produced in still air by realistic values of pitch angle or steady turning. Realistic values of atmospheric turbulence produce a moment which is significantly less than the moment produced by maneuvers in still air.

  19. The innate origin of radial and vertical gradients in a simulated galaxy disc

    NASA Astrophysics Data System (ADS)

    Navarro, Julio F.; Yozin, Cameron; Loewen, Nic; Benítez-Llambay, Alejandro; Fattahi, Azadeh; Frenk, Carlos S.; Oman, Kyle A.; Schaye, Joop; Theuns, Tom

    2018-05-01

    We examine the origin of radial and vertical gradients in the age/metallicity of the stellar component of a galaxy disc formed in the APOSTLE cosmological hydrodynamical simulations. Some of these gradients resemble those in the Milky Way, where they have sometimes been interpreted as due to internal evolution, such as scattering off giant molecular clouds, radial migration driven by spiral patterns, or orbital resonances with a bar. Secular processes play a minor role in the simulated galaxy, which lacks strong spiral or bar patterns, and where such gradients arise as a result of the gradual enrichment of a gaseous disc that is born thick but thins as it turns into stars and settles into centrifugal equilibrium. The settling is controlled by the feedback of young stars; which links the star formation, enrichment, and equilibration time-scales, inducing radial and vertical gradients in the gaseous disc and its descendent stars. The kinematics of coeval stars evolve little after birth and provide a faithful snapshot of the gaseous disc structure at the time of their formation. In this interpretation, the age-velocity dispersion relation would reflect the gradual thinning of the disc rather than the importance of secular orbit scattering; the outward flaring of stars would result from the gas disc flare rather than from radial migration; and vertical gradients would arise because the gas disc gradually thinned as it enriched. Such radial and vertical trends might just reflect the evolving properties of the parent gaseous disc, and are not necessarily the result of secular evolutionary processes.

  20. Importance of closely spaced vertical sampling in delineating chemical and microbiological gradients in groundwater studies

    USGS Publications Warehouse

    Smith, R.L.; Harvey, R.W.; LeBlanc, D.R.

    1991-01-01

    Vertical gradients of selected chemical constituents, bacterial populations, bacterial activity and electron acceptors were investigated for an unconfined aquifer contaminated with nitrate and organic compounds on Cape Cod, Massachusetts, U.S.A. Fifteen-port multilevel sampling devices (MLS's) were installed within the contaminant plume at the source of the contamination, and at 250 and 2100 m downgradient from the source. Depth profiles of specific conductance and dissolved oxygen at the downgradient sites exhibited vertical gradients that were both steep and inversely related. Narrow zones (2-4 m thick) of high N2O and NH4+ concentrations were also detected within the contaminant plume. A 27-fold change in bacterial abundance; a 35-fold change in frequency of dividing cells (FDC), an indicator of bacterial growth; a 23-fold change in 3H-glucose uptake, a measure of heterotrophic activity; and substantial changes in overall cell morphology were evident within a 9-m vertical interval at 250 m downgradient. The existence of these gradients argues for the need for closely spaced vertical sampling in groundwater studies because small differences in the vertical placement of a well screen can lead to incorrect conclusions about the chemical and microbiological processes within an aquifer.Vertical gradients of selected chemical constituents, bacterial populations, bacterial activity and electron acceptors were investigated for an unconfined aquifer contaminated with nitrate and organic compounds on Cape Cod, Massachusetts, USA. Fifteen-port multilevel sampling devices (MLS's) were installed within the contaminant plume at the source of the contamination, and at 250 and 2100 m downgradient from the source. Depth profiles of specific conductance and dissolved oxygen at the downgradient sites exhibited vertical gradients that were both steep and inversely related. Narrow zones (2-4 m thick) of high N2O and NH4+ concentrations were also detected within the contaminant plume

  1. The effect of vocal fold vertical stiffness gradient on sound production

    NASA Astrophysics Data System (ADS)

    Geng, Biao; Xue, Qian; Zheng, Xudong

    2015-11-01

    It is observed in some experimental studies on canine vocal folds (VFs) that the inferior aspect of the vocal fold (VF) is much stiffer than the superior aspect under relatively large strain. Such vertical difference is supposed to promote the convergent-divergent shape during VF vibration and consequently facilitate the production of sound. In this study, we investigate the effect of vertical variation of VF stiffness on sound production using a numerical model. The vertical variation of stiffness is produced by linearly increasing the Young's modulus and shear modulus from the superior to inferior aspects in the cover layer, and its effect on phonation is examined in terms of aerodynamic and acoustic quantities such as flow rate, open quotient, skewness of flow wave form, sound intensity and vocal efficiency. The flow-induced vibration of the VF is solved with a finite element solver coupled with 1D Bernoulli equation, which is further coupled with a digital waveguide model. This study is designed to find out whether it's beneficial to artificially induce the vertical stiffness gradient by certain implanting material in VF restoring surgery, and if it is beneficial, what gradient is the most favorable.

  2. Global grids of gravity anomalies and vertical gravity gradients at 10 km altitude from GOCE gradient data 2009-2011 and polar gravity.

    NASA Astrophysics Data System (ADS)

    Tscherning, Carl Christian; Arabelos, Dimitrios; Reguzzoni, Mirko

    2013-04-01

    The GOCE satellite measures gravity gradients which are filtered and transformed to gradients into an Earth-referenced frame by the GOCE High Level processing Facility. More than 80000000 data with 6 components are available from the period 2009-2011. IAG Arctic gravity was used north of 83 deg., while data at the Antarctic was not used due to bureaucratic restrictions by the data-holders. Subsets of the data have been used to produce gridded values at 10 km altitude of gravity anomalies and vertical gravity gradients in 20 deg. x 20 deg. blocks with 10' spacing. Various combinations and densities of data were used to obtain values in areas with known gravity anomalies. The (marginally) best choice was vertical gravity gradients selected with an approximately 0.125 deg spacing. Using Least-Squares Collocation, error-estimates were computed and compared to the difference between the GOCE-grids and grids derived from EGM2008 to deg. 512. In general a good agreement was found, however with some inconsistencies in certain areas. The computation time on a usual server with 24 processors was typically 100 minutes for a block with generally 40000 GOCE vertical gradients as input. The computations will be updated with new Wiener-filtered data in the near future.

  3. Vertical Gradients in Regional Alveolar Oxygen Tension in Supine Human Lung Imaged by Hyperpolarized 3He MRI

    PubMed Central

    Hamedani, Hooman; Shaghaghi, Hoora; Kadlecek, Stephen J.; Xin, Yi; Han, Biao; Siddiqui, Sarmad; Rajaei, Jennia; Ishii, Masaru; Rossman, Milton; Rizi, Rahim R.

    2015-01-01

    Purpose To evaluate whether regional alveolar oxygen tension (PAO2) vertical gradients imaged with hyperpolarized 3He can identify smoking-induced pulmonary alterations. To compare these gradients with common clinical measurements including pulmonary function tests, the six minute walk test, and the St. George’s Respiratory Questionnaire. Materials and Methods 8 healthy nonsmokers, 12 asymptomatic smokers, and 7 symptomatic subjects with chronic obstructive pulmonary disease (COPD) underwent two sets of back-to-back PAO2 imaging acquisitions in supine position with two opposite directions (top to bottom and bottom to top), followed by clinically standard pulmonary tests. The whole-lung mean, standard deviation (DPAO2) and vertical gradients of PAO2 along the slices were extracted, and the results were compared with clinically derived metrics. Statistical tests were performed to analyze the differences between cohorts. Results The anterior-posterior vertical gradients and DPAO2 effectively differentiated all three cohorts (p<0.05). The average vertical gradient PAO2 in healthy subjects was −1.03 ± 0.51 Torr/cm toward lower values in the posterior/dependent regions. The directional gradient was absent in smokers (0.36 ± 1.22 Torr/cm) and was in the opposite direction in COPD subjects (2.18 ± 1.54 Torr/cm). The vertical gradients correlated with Smoking History (p=0.004); BMI (p=0.037), PFT metrics (FEV1, p=0.025; and %RV/TLC, p=0.033) and with distance walked in six minutes (p=0.009). Discussion Regional PAO2 data indicate that cigarette smoke induces physiological alterations that are not being detected by the most widely used physiologic tests. PMID:25395184

  4. The influence of vertical disparity gradient and cue conflict on EEG omega complexity in Panum's limiting case.

    PubMed

    Li, Huayun; Jia, Huibin; Yu, Dongchuan

    2018-03-01

    Using behavioral measures and ERP technique, researchers discovered at least two factors could influence the final perception of depth in Panum's limiting case, which are the vertical disparity gradient and the degree of cue conflict between two- and three-dimensional shapes. Although certain event-related potential components have been proved to be sensitive to the different levels of these two factors, some methodological limitations existed in this technique. In this study, we proposed that the omega complexity of EEG signal may serve as an important supplement of the traditional event-related potential technique. We found that the trials with lower vertical gradient disparity have lower omega complexity (i.e., higher global functional connectivity) of the occipital region, especially that of the right-occipital hemisphere. Moreover, for occipital omega complexity, the trials with low-cue conflict have significantly larger omega complexity than those with medium- and high-cue conflict. It is also found that the electrodes located in the middle line of the occipital region (i.e., POz and Oz) are more crucial to the impact of different levels of cue conflict on omega complexity than the other electrodes located in the left- and right-occipital hemispheres. These evidences demonstrated that the EEG omega complexity could reflect distinct neural activities evoked by Panum's limiting case configurations, with different levels of vertical disparity gradient and cue conflict. Besides, the influence of vertical disparity gradient and cue conflict on omega complexity may be regional dependent. NEW & NOTEWORTHY The EEG omega complexity could reflect distinct neural activities evoked by Panum's limiting case configurations with different levels of vertical disparity gradient and cue conflict. The influence of vertical disparity gradient and cue conflict on omega complexity is regional dependent. The omega complexity of EEG signal can serve as an important supplement of the

  5. Demonstration of an Enhanced Vertical Magnetic Gradient System for UXO

    DTIC Science & Technology

    2008-12-01

    fluxgate magnetometers , data recording console, laser altimeter, and acoustic altimeters were tested to ensure proper operation and performance. The VG...Simultaneous Electromagnetic Induction and Magnetometer System WAA wide area assessment ACKNOWLEDGEMENTS We wish to express our sincere...sensors. The benefits of vertical gradient (VG) configurations in magnetometer systems are common knowledge, and these configurations are routinely

  6. The vertical metallicity gradients of mono-age stellar populations in the Milky Way with the RAVE and Gaia data

    NASA Astrophysics Data System (ADS)

    Ciucǎ, Ioana; Kawata, Daisuke; Lin, Jane; Casagrande, Luca; Seabroke, George; Cropper, Mark

    2018-03-01

    We investigate the vertical metallicity gradients of five mono-age stellar populations between 0 and 11 Gyr for a sample of 18 435 dwarf stars selected from the cross-matched Tycho-Gaia Astrometric Solution and Radial Velocity Experiment (RAVE) Data Release 5. We find a correlation between the vertical metallicity gradients and age, with no vertical metallicity gradient in the youngest population and an increasingly steeper negative vertical metallicity gradient for the older stellar populations. The metallicity at disc plane remains almost constant between 2 and 8 Gyr, and it becomes significantly lower for the 8 < τ ≤ 11 Gyr population. The current analysis also reveals that the intrinsic dispersion in metallicity increases steadily with age. We discuss that our results are consistent with a scenario that (thin) disc stars formed from a flaring (thin) star-forming disc.

  7. Effect of freeze/thaw cycles on several biomarkers in urine from patients with kidney disease.

    PubMed

    Zhang, Yinan; Luo, Yi; Lu, Huijuan; Wang, Niansong; Shen, Yixie; Chen, Ruihua; Fang, Pingyan; Yu, Hong; Wang, Congrong; Jia, Weiping

    2015-04-01

    Urine samples were collected from eleven randomly selected patients with kidney disease, including diabetic nephropathy, chronic nephritis, and nephritic syndrome. Urine samples were treated with one of four protocols for freezing and thawing: freeze directly and thaw directly; freeze directly and thaw by temperature gradient; freeze by temperature gradient and thaw directly; and freeze by temperature gradient and thaw by temperature gradient. After one to six freeze/thaw cycles at -20°C or -80°C, different biomarkers showed differential stabilities. The concentrations of total protein, calcium, and potassium did not change significantly after five freeze/thaw cycles at either -20°C or -80°C. Albumin could only sustain three freeze/thaw cycles at -20°C before it started to degrade. We recommend that urine be stored at -80°C as albumin and the organic ions could sustain five and six freeze/thaw cycles, respectively, using the simple "direct freeze and direct thaw" protocol. Furthermore, in most cases, gradient freeze/thaw cycles are not necessary for urine sample storage.

  8. Numerical Study on Density Gradient Carbon-Carbon Composite for Vertical Launching System

    NASA Astrophysics Data System (ADS)

    Yoon, Jin-Young; Kim, Chun-Gon; Lim, Juhwan

    2018-04-01

    This study presents new carbon-carbon (C/C) composite that has a density gradient within single material, and estimates its heat conduction performance by a numerical method. To address the high heat conduction of a high-density C/C, which can cause adhesion separation in the steel structures of vertical launching systems, density gradient carbon-carbon (DGCC) composite is proposed due to its exhibiting low thermal conductivity as well as excellent ablative resistance. DGCC is manufactured by hybridizing two different carbonization processes into a single carbon preform. One part exhibits a low density using phenolic resin carbonization to reduce heat conduction, and the other exhibits a high density using thermal gradient-chemical vapor infiltration for excellent ablative resistance. Numerical analysis for DGCC is performed with a heat conduction problem, and internal temperature distributions are estimated by the forward finite difference method. Material properties of the transition density layer, which is inevitably formed during DGCC manufacturing, are assumed to a combination of two density layers for numerical analysis. By comparing numerical results with experimental data, we validate that DGCC exhibits a low thermal conductivity, and it can serve as highly effective ablative material for vertical launching systems.

  9. Contribution of Field Strength Gradients to the Net Vertical Current of Active Regions

    NASA Astrophysics Data System (ADS)

    Vemareddy, P.

    2017-12-01

    We examined the contribution of field strength gradients for the degree of net vertical current (NVC) neutralization in active regions (ARs). We used photospheric vector magnetic field observations of AR 11158 obtained by Helioseismic and Magnetic Imager on board SDO and Hinode. The vertical component of the electric current is decomposed into twist and shear terms. The NVC exhibits systematic evolution owing to the presence of the sheared polarity inversion line between rotating and shearing magnetic regions. We found that the sign of shear current distribution is opposite in dominant pixels (60%–65%) to that of twist current distribution, and its time profile bears no systematic trend. This result indicates that the gradient of magnetic field strength contributes to an opposite signed, though smaller in magnitude, current to that contributed by the magnetic field direction in the vertical component of the current. Consequently, the net value of the shear current is negative in both polarity regions, which when added to the net twist current reduces the direct current value in the north (B z > 0) polarity, resulting in a higher degree of NVC neutralization. We conjecture that the observed opposite signs of shear and twist currents are an indication, according to Parker, that the direct volume currents of flux tubes are canceled by their return currents, which are contributed by field strength gradients. Furthermore, with the increase of spatial resolution, we found higher values of twist, shear current distributions. However, the resolution effect is more useful in resolving the field strength gradients, and therefore suggests more contribution from shear current for the degree of NVC neutralization.

  10. In situ synthesis of bilayered gradient poly(vinyl alcohol)/hydroxyapatite composite hydrogel by directional freezing-thawing and electrophoresis method.

    PubMed

    Su, Cui; Su, Yunlan; Li, Zhiyong; Haq, Muhammad Abdul; Zhou, Yong; Wang, Dujin

    2017-08-01

    Bilayered poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) composite hydrogels with anisotropic and gradient mechanical properties were prepared by the combination of directional freezing-thawing (DFT) and electrophoresis method. Firstly, PVA hydrogels with aligned channel structure were prepared by the DFT method. Then, HA nanoparticles were in situ synthesized within the PVA hydrogels via electrophoresis. By controlling the time of the electrophoresis process, a bilayered gradient hydrogel containing HA particles in only half of the gel region was obtained. The PVA/HA composite hydrogel exhibited gradient mechanical strength depending on the distance to the cathode. The gradient initial tensile modulus ranging from 0.18MPa to 0.27MPa and the gradient initial compressive modulus from 0.33MPa to 0.51MPa were achieved. The binding strength of the two regions was relatively high and no apparent internal stress or defect was observed at the boundary. The two regions of the bilayered hydrogel also showed different osteoblast cell adhesion properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Freeze-cast alumina pore networks: Effects of freezing conditions and dispersion medium

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Miller, S. M.; Xiao, X.; Faber, K. T.

    Alumina ceramics were freeze-cast from water- and camphene-based slurries under varying freezing conditions and examined using X-ray computed tomography (XCT). Pore network characteristics, i.e., porosity, pore size, geometric surface area, and tortuosity, were measured from XCT reconstructions and the data were used to develop a model to predict feature size from processing conditions. Classical solidification theory was used to examine relationships between pore size, temperature gradients, and freezing front velocity. Freezing front velocity was subsequently predicted from casting conditions via the two-phase Stefan problem. Resulting models for water-based samples agreed with solidification-based theories predicting lamellar spacing of binary eutectic alloys,more » and models for camphene-based samples concurred with those for dendritic growth. Relationships between freezing conditions and geometric surface area were also modeled by considering the inverse relationship between pore size and surface area. Tortuosity was determined to be dependent primarily on the type of dispersion medium. (C) 2015 Elsevier Ltd. All rights reserved.« less

  12. Vertical gradients and seasonal variation in stem CO2 efflux within a Norway spruce stand.

    PubMed

    Tarvainen, Lasse; Räntfors, Mats; Wallin, Göran

    2014-05-01

    Stem CO2 efflux is known to vary seasonally and vertically along tree stems. However, annual tree- and stand-scale efflux estimates are commonly based on measurements made only a few times a year, during daytime and at breast height. In this study, the effect of these simplifying assumptions on annual efflux estimates and their influence on the estimates of the importance of stems in stand-scale carbon cycling are evaluated. In order to assess the strength of seasonal, diurnal and along-stem variability in CO2 efflux, half-hourly measurements were carried out at three heights on three mature Norway spruce (Picea abies (L.) Karst.) trees over a period of 3 years. Making the common assumption of breast height efflux rates being representative of the entire stem was found to result in underestimations of 10-17% in the annual tree-scale CO2 efflux. Upscaling using only daytime measurements from breast height increased the underestimation to 15-20%. Furthermore, the results show that the strength of the vertical gradient varies seasonally, being strongest in the early summer and non-existent during the cool months. The observed seasonality in the vertical CO2 efflux gradient could not be explained by variation in stem temperature, temperature response of the CO2 efflux (Q10), outer-bark permeability, CO2 transport in the xylem or CO2 release from the phloem. However, the estimated CO2 concentration immediately beneath the bark was considerably higher in the upper stem during the main period of diameter growth, coinciding with the strongest vertical efflux gradient. These results suggest that higher growth rates in the upper stem are the main cause for the observed vertical variation in the stem CO2 effluxes. Furthermore, the results indicate that accounting for the vertical efflux variation is essential for assessments of the importance of stems in stand-scale carbon cycling. © The Author 2014. Published by Oxford University Press. All rights reserved.

  13. Gelatin freeze casting of biomimetic titanium alloy with anisotropic and gradient pore structure.

    PubMed

    Zhang, Lei; Le Coz-Botrel, Ronan; Beddoes, Charlotte; Sjöström, Terje; Su, Bo

    2017-01-17

    Titanium is a material commonly used for dental and orthopaedic implants. However, due to large differences in properties between the titanium metal and the natural bone, stress shielding has been observed in the surrounding area, resulting in bone atrophy, and thus has raised concerns of the use of this material. Ideally implant materials should possess similar properties to the surrounding tissues in order to distribute the load as the joint would naturally, while also possessing a similar porous structure to the bone to enable interaction with the surrounding material. In this paper we report the formation of aligned porous titanium alloy scaffolds with the use of unidirectional freeze casting with a temperature gradient. The resulting scaffolds had a dense bottom part with sufficient strength for loading, while the top part remaining porous in order to allow bone growth in the scaffold and fully integrating with the surrounding tissue. The anisotropic nature of the pores within the titanium alloy samples were observed via micro computed tomography, where a gradient structure similar to bone was observed. The compressive strength of the fabricated scaffolds was found to be up to 427 MPa when measured with the pores aligned with the applied load, depending on the pore density. This is within the range of cortical bone.

  14. Oval gradient coils for an open magnetic resonance imaging system with a vertical magnetic field.

    PubMed

    Matsuzawa, Koki; Abe, Mitsushi; Kose, Katsumi; Terada, Yasuhiko

    2017-05-01

    Existing open magnetic resonance imaging (MRI) systems use biplanar gradient coils for the spatial encoding of signals. We propose using novel oval gradient coils for an open vertical-field MRI. We designed oval gradients for a 0.3T open MRI system and showed that such a system could outperform a traditional biplanar gradient system while maintaining adequate gradient homogeneity and subject accessibility. Such oval gradient coils would exhibit high efficiency, low inductance and resistance, and high switching capability. Although the designed oval Y and Z coils showed more heat dissipation and less cooling capability than biplanar coils with the same gap, they showed an efficient heat-dissipation path to the surrounding air, which would alleviate the heat problem. The performance of the designed oval-coil system was demonstrated experimentally by imaging a human hand. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. A meridional structure of static stability and ozone vertical gradient around the tropopause in the Southern Hemisphere extratropics

    NASA Astrophysics Data System (ADS)

    Tomikawa, Y.; Yamanouchi, T.

    2010-08-01

    An analysis of the static stability and ozone vertical gradient in the ozone tropopause based (OTB) coordinate is applied to the ozonesonde data at 10 stations in the Southern Hemisphere (SH) extratropics. The tropopause inversion layer (TIL) with a static stability maximum just above the tropopause shows similar seasonal variations at two Antarctic stations, which are latitudinally far from each other. Since the sunshine hour varies with time in a quite different way between these two stations, it implies that the radiative heating due to solar ultraviolet absorption of ozone does not contribute to the seasonal variation of the TIL. A meridional section of the static stability in the OTB coordinate shows that the static stability just above the tropopause has a large latitudinal gradient between 60° S and 70° S in austral winter because of the absence of the TIL over the Antarctic. It is accompanied by an increase of westerly shear with height above the tropopause, so that the polar-night jet is formed above this latitude region. This result suggests a close relationship between the absence of the TIL and the stratospheric polar vortex in the Antarctic winter. A vertical gradient of ozone mixing ratio, referred to as ozone vertical gradient, around the tropopause shows similar latitudinal and seasonal variations with the static stability in the SH extratropics. In a height region above the TIL, a small ozone vertical gradient in the midlatitudes associated with the Antarctic ozone hole is observed in a height region of the subvortex but not around the polar vortex. This is a clear evidence of active latitudinal mixing between the midlatitudes and subvortex.

  16. Shrub type dominates the vertical distribution of leaf C : N : P stoichiometry across an extensive altitudinal gradient

    NASA Astrophysics Data System (ADS)

    Zhao, Wenqiang; Reich, Peter B.; Yu, Qiannan; Zhao, Ning; Yin, Chunying; Zhao, Chunzhang; Li, Dandan; Hu, Jun; Li, Ting; Yin, Huajun; Liu, Qing

    2018-04-01

    Understanding leaf stoichiometric patterns is crucial for improving predictions of plant responses to environmental changes. Leaf stoichiometry of terrestrial ecosystems has been widely investigated along latitudinal and longitudinal gradients. However, very little is known about the vertical distribution of leaf C : N : P and the relative effects of environmental parameters, especially for shrubs. Here, we analyzed the shrub leaf C, N and P patterns in 125 mountainous sites over an extensive altitudinal gradient (523-4685 m) on the Tibetan Plateau. Results showed that the shrub leaf C and C : N were 7.3-47.5 % higher than those of other regional and global flora, whereas the leaf N and N : P were 10.2-75.8 % lower. Leaf C increased with rising altitude and decreasing temperature, supporting the physiological acclimation mechanism that high leaf C (e.g., alpine or evergreen shrub) could balance the cell osmotic pressure and resist freezing. The largest leaf N and high leaf P occurred in valley region (altitude 1500 m), likely due to the large nutrient leaching from higher elevations, faster litter decomposition and nutrient resorption ability of deciduous broadleaf shrub. Leaf N : P ratio further indicated increasing N limitation at higher altitudes. Interestingly, drought severity was the only climatic factor positively correlated with leaf N and P, which was more appropriate for evaluating the impact of water status than precipitation. Among the shrub ecosystem and functional types (alpine, subalpine, montane, valley, evergreen, deciduous, broadleaf, and conifer), their leaf element contents and responses to environments were remarkably different. Shrub type was the largest contributor to the total variations in leaf stoichiometry, while climate indirectly affected the leaf C : N : P via its interactive effects on shrub type or soil. Collectively, the large heterogeneity in shrub type was the most important factor explaining the overall leaf C : N : P variations

  17. A refined model of sedimentary rock cover in the southeastern part of the Congo basin from GOCE gravity and vertical gravity gradient observations

    NASA Astrophysics Data System (ADS)

    Martinec, Zdeněk; Fullea, Javier

    2015-03-01

    We aim to interpret the vertical gravity and vertical gravity gradient of the GOCE-GRACE combined gravity model over the southeastern part of the Congo basin to refine the published model of sedimentary rock cover. We use the GOCO03S gravity model and evaluate its spherical harmonic representation at or near the Earth's surface. In this case, the gradiometry signals are enhanced as compared to the original measured GOCE gradients at satellite height and better emphasize the spatial pattern of sedimentary geology. To avoid aliasing, the omission error of the modelled gravity induced by the sedimentary rocks is adjusted to that of the GOCO03S gravity model. The mass-density Green's functions derived for the a priori structure of the sediments show a slightly greater sensitivity to the GOCO03S vertical gravity gradient than to the vertical gravity. Hence, the refinement of the sedimentary model is carried out for the vertical gravity gradient over the basin, such that a few anomalous values of the GOCO03S-derived vertical gravity gradient are adjusted by refining the model. We apply the 5-parameter Helmert's transformation, defined by 2 translations, 1 rotation and 2 scale parameters that are searched for by the steepest descent method. The refined sedimentary model is only slightly changed with respect to the original map, but it significantly improves the fit of the vertical gravity and vertical gravity gradient over the basin. However, there are still spatial features in the gravity and gradiometric data that remain unfitted by the refined model. These may be due to lateral density variation that is not contained in the model, a density contrast at the Moho discontinuity, lithospheric density stratifications or mantle convection. In a second step, the refined sedimentary model is used to find the vertical density stratification of sedimentary rocks. Although the gravity data can be interpreted by a constant sedimentary density, such a model does not correspond to

  18. Use of vertical temperature gradients for prediction of tidal flat sediment characteristics

    USGS Publications Warehouse

    Miselis, Jennifer L.; Holland, K. Todd; Reed, Allen H.; Abelev, Andrei

    2012-01-01

    Sediment characteristics largely govern tidal flat morphologic evolution; however, conventional methods of investigating spatial variability in lithology on tidal flats are difficult to employ in these highly dynamic regions. In response, a series of laboratory experiments was designed to investigate the use of temperature diffusion toward sediment characterization. A vertical thermistor array was used to quantify temperature gradients in simulated tidal flat sediments of varying compositions. Thermal conductivity estimates derived from these arrays were similar to measurements from a standard heated needle probe, which substantiates the thermistor methodology. While the thermal diffusivities of dry homogeneous sediments were similar, diffusivities for saturated homogeneous sediments ranged approximately one order of magnitude. The thermal diffusivity of saturated sand was five times the thermal diffusivity of saturated kaolin and more than eight times the thermal diffusivity of saturated bentonite. This suggests that vertical temperature gradients can be used for distinguishing homogeneous saturated sands from homogeneous saturated clays and perhaps even between homogeneous saturated clay types. However, experiments with more realistic tidal flat mixtures were less discriminating. Relationships between thermal diffusivity and percent fines for saturated mixtures varied depending upon clay composition, indicating that clay hydration and/or water content controls thermal gradients. Furthermore, existing models for the bulk conductivity of sediment mixtures were improved only through the use of calibrated estimates of homogeneous end-member conductivity and water content values. Our findings suggest that remotely sensed observations of water content and thermal diffusivity could only be used to qualitatively estimate tidal flat sediment characteristics.

  19. Crystal Growth of CdTe by Gradient Freeze in Universal Multizone Crystallizator (UMC)

    NASA Technical Reports Server (NTRS)

    Su, Ching-Hua; Lehoczky, S. L.; Li, C.; Knuteson, D.; Raghothamachar, B.; Dudley, M.; Szoke, J.; Barczy, P.

    2004-01-01

    In the case of unsealed melt growth of an array of II-VI compounds, namely, CdTe, CdZnTe and ZnSe, there is a tremendous amount of experimental data describing the correlations between melt conditions and crystal quality. The results imply that the crystallinity quality can be improved if the melt was markedly superheated or long-time held before growth. It is speculated that after high superheating the associated complex dissociate and the spontaneous nucleation is retarded. In this study, crystals of CdTe were grown from melts which have undergone different thermal history by the unseeded gradient freeze method using the Universal Multizone Crystallizator (UMC). The effects of melt conditions on the quality of grown crystal were studied by various characterization techniques, including Synchrotron White Beam X-ray Topography (SWSXT), infrared microscopy, chemical analysis by glow discharge mass spectroscopy (GDMS), electrical conductivity and Hall measurements.

  20. Effect of Vertical Concentration Gradient on Globally Planar Detonation with Detailed Reaction Mechanism

    NASA Astrophysics Data System (ADS)

    Song, Qingguana; Wang, Cheng; Han, Yong; Gao, Dayuan; Duan, Yingliang

    2017-06-01

    Since detonation often initiates and propagates in the non-homogeneous mixtures, investigating its behavior in non-uniform mixtures is significant not only for the industrial explosion in the leakage combustible gas, but also for the experimental investigations with a vertical concentration gradient caused by the difference in the molecular weight of gas mixture. Objective of this work is to show the detonation behavior in the mixture with different concentration gradients with detailed chemical reaction mechanism. A globally planar detonation in H2-O2 system is simulated by a high-resolution code based on the fifth-order weighted essentially non-oscillatory (WENO) scheme in spatial discretization and the third-order Additive Runge-Kutta schemes in time discretization. The different shocked combustion modes appear in the rich-fuel and poor-fuel layers due to the concentration gradient effect. Globally, for the cases with the lower gradient detonation can be sustained in a way of the alternation of the multi-heads mode and single-head mode, whereas for the cases with the higher gradient detonation propagates with a single-head mode. Institute of Chemical Materials, CAEP.

  1. Light drives vertical gradients of leaf morphology in a sugar maple (Acer saccharum) forest.

    PubMed

    Coble, Adam P; Cavaleri, Molly A

    2014-02-01

    Leaf mass per area (LMA, g m(-2)) is an essential trait for modeling canopy function due to its strong association with photosynthesis, respiration and leaf nitrogen. Leaf mass per area, which is influenced by both leaf thickness and density (LMA = thickness × density), generally increases from the bottom to the top of tree canopies, yet the mechanisms behind this universal pattern are not yet resolved. For decades, the light environment was assumed to be the most influential driver of within-canopy variation in LMA, yet recent evidence has shown hydrostatic gradients to be more important in upper canopy positions, especially in tall evergreen trees in temperate and tropical forests. The aim of this study was to disentangle the importance of various environmental drivers on vertical LMA gradients in a mature sugar maple (Acer saccharum Marshall) forest. We compared LMA, leaf density and leaf thickness relationships with height, light and predawn leaf water potential (ΨPre) within a closed and an exposed canopy to assess leaf morphological traits at similar heights but different light conditions. Contrary to our expectations and recent findings in the literature, we found strong evidence that light was the primary driver of vertical gradients in leaf morphology. At similar heights (13-23 m), LMA was greater within the exposed canopy than the closed canopy, and light had a stronger influence over LMA compared with ΨPre. Light also had a stronger influence over both leaf thickness and density compared with ΨPre; however, the increase in LMA within both canopy types was primarily due to increasing leaf thickness with increasing light availability. This study provides strong evidence that canopy structure and crown exposure, in addition to height, should be considered as a parameter for determining vertical patterns in LMA and modeling canopy function.

  2. Spiral MRI on a 9.4T Vertical-bore Superconducting Magnet Using Unshielded and Self-shielded Gradient Coils.

    PubMed

    Kodama, Nao; Setoi, Ayana; Kose, Katsumi

    2018-04-10

    Spiral MRI sequences were developed for a 9.4T vertical standard bore (54 mm) superconducting magnet using unshielded and self-shielded gradient coils. Clear spiral images with 64-shot scan were obtained with the self-shielded gradient coil, but severe shading artifacts were observed for the spiral-scan images acquired with the unshielded gradient coil. This shading artifact was successfully corrected with a phase-correction technique using reference scans that we developed based on eddy current field measurements. We therefore concluded that spiral imaging sequences can be installed even for unshielded gradient coils if phase corrections are performed using the reference scans.

  3. Freeze Technology for Nuclear Applications - 13590

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rostmark, Susanne C.; Knutsson, Sven; Lindberg, Maria

    2013-07-01

    Freezing of soil materials is a complicated process of a number of physical processes: - freezing of pore water in a thermal gradient, - cryogenic suction causing water migration and - ice formation expanding pores inducing frost heave. Structural changes due to increase of effective stress during freezing also take place. The over consolidation gives a powerful dewatering/drying effect and the freeze process causes separation of contaminates. Artificial ground freezing (AGF is a well established technique first practiced in south Wales, as early as 1862. AGF is mostly used to stabilize tunnels and excavations. During the last ten years underwatermore » applications of freeze technologies based on the AGF have been explored in Sweden. The technology can, and has been, used in many different steps in a remediation action. Freeze Sampling where undisturbed samples are removed in both soft and hard sediment/sludge, Freeze Dredging; retrieval of sediment with good precision and minimal redistribution, and Freeze Drying; volume reduction of contaminated sludge/sediment. The application of these technologies in a nuclear or radioactive environment provides several advantages. Sampling by freezing gives for example an advantage of an undisturbed sample taken at a specified depth, salvaging objects by freezing or removal of sludges is other applications of this, for the nuclear industry, novel technology. (authors)« less

  4. Increased spring freezing vulnerability for alpine shrubs under early snowmelt.

    PubMed

    Wheeler, J A; Hoch, G; Cortés, A J; Sedlacek, J; Wipf, S; Rixen, C

    2014-05-01

    Alpine dwarf shrub communities are phenologically linked with snowmelt timing, so early spring exposure may increase risk of freezing damage during early development, and consequently reduce seasonal growth. We examined whether environmental factors (duration of snow cover, elevation) influenced size and the vulnerability of shrubs to spring freezing along elevational gradients and snow microhabitats by modelling the past frequency of spring freezing events. We sampled biomass and measured the size of Salix herbacea, Vaccinium myrtillus, Vaccinium uliginosum and Loiseleuria procumbens in late spring. Leaves were exposed to freezing temperatures to determine the temperature at which 50% of specimens are killed for each species and sampling site. By linking site snowmelt and temperatures to long-term climate measurements, we extrapolated the frequency of spring freezing events at each elevation, snow microhabitat and per species over 37 years. Snowmelt timing was significantly driven by microhabitat effects, but was independent of elevation. Shrub growth was neither enhanced nor reduced by earlier snowmelt, but decreased with elevation. Freezing resistance was strongly species dependent, and did not differ along the elevation or snowmelt gradient. Microclimate extrapolation suggested that potentially lethal freezing events (in May and June) occurred for three of the four species examined. Freezing events never occurred on late snow beds, and increased in frequency with earlier snowmelt and higher elevation. Extrapolated freezing events showed a slight, non-significant increase over the 37-year record. We suggest that earlier snowmelt does not enhance growth in four dominant alpine shrubs, but increases the risk of lethal spring freezing exposure for less freezing-resistant species.

  5. Free drainage of aqueous foams: Container shape effects on capillarity and vertical gradients

    NASA Astrophysics Data System (ADS)

    Saint-Jalmes, A.; Vera, M. U.; Durian, D. J.

    2000-06-01

    The standard drainage equation applies only to foam columns of constant cross-sectional area. Here, we generalize to include the effects of arbitrary container shape and develop an exact solution for an exponential, "Eiffel Tower", sample. This geometry largely eliminates vertical wetness gradients, and hence capillary effects, and should permit a clean test of dissipation mechanisms. Agreement with experiment is not achieved at late times, however, highlighting the importance of both boundary conditions and coarsening.

  6. Spiral MRI on a 9.4T Vertical-bore Superconducting Magnet Using Unshielded and Self-shielded Gradient Coils

    PubMed Central

    Kodama, Nao; Setoi, Ayana; Kose, Katsumi

    2018-01-01

    Spiral MRI sequences were developed for a 9.4T vertical standard bore (54 mm) superconducting magnet using unshielded and self-shielded gradient coils. Clear spiral images with 64-shot scan were obtained with the self-shielded gradient coil, but severe shading artifacts were observed for the spiral-scan images acquired with the unshielded gradient coil. This shading artifact was successfully corrected with a phase-correction technique using reference scans that we developed based on eddy current field measurements. We therefore concluded that spiral imaging sequences can be installed even for unshielded gradient coils if phase corrections are performed using the reference scans. PMID:28367906

  7. Characterization of freezing precipitation events through other meteorological variables and their recent changes over Northern Extratropics

    NASA Astrophysics Data System (ADS)

    Groisman, P. Y.; Yin, X.; Bulygina, O.

    2017-12-01

    Freezing precipitation events intertwine with agriculture, recreation, energy consumption, and seasonal transportation cycles of human activities. Using supplementary synoptic reports at 1,500 long-term stations of North America and Northern Eurasia, we created climatology of freezing precipitation near the surface and found significant changes (increases) in these occurrences in the past decade at high latitudes/elevations (Groisman et al. 2016; updated). Firstly, we document narrow boundaries of near surface temperature and humidity fields when freezing precipitation events occur; these are necessary but insufficient conditions of their occurrence. Secondly, using the upper air data at the sites collocated with in situ observations of freezing events, we quantify the typical pattern of lower troposphere temperature anomalies during freezing events: At the same locations and Julian days, the presence of freezing event at the surface is associated with significantly warmer temperatures in the lower troposphere; comparison of temperatures at nearest days before and after the freezing events with days during these events also shows statistically significant positive temperature anomalies in the lower troposphere to 500 hPa (on average, +3 to 4 °C) In the days with freezing events, vertical air temperature gradients between surface and 850 hPa become less than usual with frequent inversions, when the tropospheric air is warmer than at the surface. The above features of the lower tropospheric temperature, near-surface temperature and humidity represent a combination of weather conditions conducive for precipitation, if it happens, falling in the freezing rain form. The in situ reports of freezing events at synoptic stations allow us to estimate temporary and spatial distributions of such "special weather conditions". Thus, a posteriori high probability of freezing events under these weather conditions invokes similar probabilities of freezing rain over the ungauged

  8. Universal pion freeze-out in heavy-ion collisions.

    PubMed

    Adamová, D; Agakichiev, G; Appelshäuser, H; Belaga, V; Braun-Munzinger, P; Castillo, A; Cherlin, A; Damjanović, S; Dietel, T; Dietrich, L; Drees, A; Esumi, S I; Filimonov, K; Fomenko, K; Fraenkel, Z; Garabatos, C; Glässel, P; Hering, G; Holeczek, J; Kushpil, V; Lenkeit, B; Ludolphs, W; Maas, A; Marín, A; Milosević, J; Milov, A; Miśkowiec, D; Panebrattsev, Yu; Petchenova, O; Petrácek, V; Pfeiffer, A; Rak, J; Ravinovich, I; Rehak, P; Sako, H; Schmitz, W; Schukraft, J; Sedykh, S; Shimansky, S; Slívová, J; Specht, H J; Stachel, J; Sumbera, M; Tilsner, H; Tserruya, I; Wessels, J P; Wienold, T; Windelband, B; Wurm, J P; Xie, W; Yurevich, S; Yurevich, V

    2003-01-17

    Based on an evaluation of data on pion interferometry and on particle yields at midrapidity, we propose a universal condition for thermal freeze-out of pions in heavy-ion collisions. We show that freeze-out occurs when the mean free path of pions lambda(f) reaches a value of about 1 fm, which is much smaller than the spatial extent of the system at freeze-out. This critical mean free path is independent of the centrality of the collision and beam energy from the Alternating Gradient Synchrotron to the Relativistic Heavy Ion Collider.

  9. Stable Computation of the Vertical Gradient of Potential Field Data Based on Incorporating the Smoothing Filters

    NASA Astrophysics Data System (ADS)

    Baniamerian, Jamaledin; Liu, Shuang; Abbas, Mahmoud Ahmed

    2018-04-01

    The vertical gradient is an essential tool in interpretation algorithms. It is also the primary enhancement technique to improve the resolution of measured gravity and magnetic field data, since it has higher sensitivity to changes in physical properties (density or susceptibility) of the subsurface structures than the measured field. If the field derivatives are not directly measured with the gradiometers, they can be calculated from the collected gravity or magnetic data using numerical methods such as those based on fast Fourier transform technique. The gradients behave similar to high-pass filters and enhance the short-wavelength anomalies which may be associated with either small-shallow sources or high-frequency noise content in data, and their numerical computation is susceptible to suffer from amplification of noise. This behaviour can adversely affect the stability of the derivatives in the presence of even a small level of the noise and consequently limit their application to interpretation methods. Adding a smoothing term to the conventional formulation of calculating the vertical gradient in Fourier domain can improve the stability of numerical differentiation of the field. In this paper, we propose a strategy in which the overall efficiency of the classical algorithm in Fourier domain is improved by incorporating two different smoothing filters. For smoothing term, a simple qualitative procedure based on the upward continuation of the field to a higher altitude is introduced to estimate the related parameters which are called regularization parameter and cut-off wavenumber in the corresponding filters. The efficiency of these new approaches is validated by computing the first- and second-order derivatives of noise-corrupted synthetic data sets and then comparing the results with the true ones. The filtered and unfiltered vertical gradients are incorporated into the extended Euler deconvolution to estimate the depth and structural index of a magnetic

  10. Heating-freezing effects on the orientation of kaolin clay particles

    DOE PAGES

    Jaradat, Karam A.; Darbari, Zubin; Elbakhshwan, Mohamed; ...

    2017-09-29

    The effects of temperature changes on the particle orientation of a consolidated kaolin are studied using XRD experiments. Here, two sets of equipment were utilized in this study: a benchtop equipment, and a synchrotron beamline at the National Synchrotron Light Source II (NSLS-II) at Brookhaven National Laboratory. The kaolin specimens tested in the benchtop XRD were subjected to elevated and freezing temperatures ex-situ, while those used for the NSLS-II experiment were exposed to the temperature changes in-situ. The temperatures considered in this study range from freezing (-10 °C) to elevated temperature below boiling (90 °C). The thermally-induced reorientation of claymore » mineral particles is highly dependent on the relative orientation of the clay mineral particles with respect to the applied thermal gradient. For example, kaolin samples with kaolinite particles oriented perpendicular to the thermal gradient, and to the expected thermally-induced pore water flow, experience much higher particles reorientations compared to samples with particles initially oriented parallel to the thermal gradient. Lastly, freezing kaolin preserved its microstructure as ice crystals form.« less

  11. Heating-freezing effects on the orientation of kaolin clay particles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jaradat, Karam A.; Darbari, Zubin; Elbakhshwan, Mohamed

    The effects of temperature changes on the particle orientation of a consolidated kaolin are studied using XRD experiments. Here, two sets of equipment were utilized in this study: a benchtop equipment, and a synchrotron beamline at the National Synchrotron Light Source II (NSLS-II) at Brookhaven National Laboratory. The kaolin specimens tested in the benchtop XRD were subjected to elevated and freezing temperatures ex-situ, while those used for the NSLS-II experiment were exposed to the temperature changes in-situ. The temperatures considered in this study range from freezing (-10 °C) to elevated temperature below boiling (90 °C). The thermally-induced reorientation of claymore » mineral particles is highly dependent on the relative orientation of the clay mineral particles with respect to the applied thermal gradient. For example, kaolin samples with kaolinite particles oriented perpendicular to the thermal gradient, and to the expected thermally-induced pore water flow, experience much higher particles reorientations compared to samples with particles initially oriented parallel to the thermal gradient. Lastly, freezing kaolin preserved its microstructure as ice crystals form.« less

  12. Analysis of the accelerated crucible rotation technique applied to the gradient freeze growth of cadmium zinc telluride

    NASA Astrophysics Data System (ADS)

    Divecha, Mia S.; Derby, Jeffrey J.

    2017-06-01

    We employ finite-element modeling to assess the effects of the accelerated crucible rotation technique (ACRT) on cadmium zinc telluride (CZT) crystals grown from a gradient freeze system. Via consideration of tellurium segregation and transport, we show, for the first time, that steady growth from a tellurium-rich melt produces persistent undercooling in front of the growth interface, likely leading to morphological instability. The application of ACRT rearranges melt flows and tellurium transport but, in contrast to conventional wisdom, does not altogether eliminate undercooling of the melt. Rather, a much more complicated picture arises, where spatio-temporal realignment of undercooled melt may act to locally suppress instability. A better understanding of these mechanisms and quantification of their overall effects will allow for future growth optimization.

  13. Estimation of the depth to the fresh-water/salt-water interface from vertical head gradients in wells in coastal and island aquifers

    NASA Astrophysics Data System (ADS)

    Izuka, Scot K.; Gingerich, Stephen B.

    An accurate estimate of the depth to the theoretical interface between fresh, water and salt water is critical to estimates of well yields in coastal and island aquifers. The Ghyben-Herzberg relation, which is commonly used to estimate interface depth, can greatly underestimate or overestimate the fresh-water thickness, because it assumes no vertical head gradients and no vertical flow. Estimation of the interface depth needs to consider the vertical head gradients and aquifer anisotropy that may be present. This paper presents a method to calculate vertical head gradients using water-level measurements made during drilling of a partially penetrating well; the gradient is then used to estimate interface depth. Application of the method to a numerically simulated fresh-water/salt-water system shows that the method is most accurate when the gradient is measured in a deeply penetrating well. Even using a shallow well, the method more accurately estimates the interface position than does the Ghyben-Herzberg relation where substantial vertical head gradients exist. Application of the method to field data shows that drilling, collection methods of water-level data, and aquifer inhomogeneities can cause difficulties, but the effects of these difficulties can be minimized. Résumé Une estimation précise de la profondeur de l'interface théorique entre l'eau douce et l'eau salée est un élément critique dans les estimations de rendement des puits dans les aquifères insulaires et littoraux. La relation de Ghyben-Herzberg, qui est habituellement utilisée pour estimer la profondeur de cette interface, peut fortement sous-estimer ou surestimer l'épaisseur de l'eau douce, parce qu'elle suppose l'absence de gradient vertical de charge et d'écoulement vertical. L'estimation de la profondeur de l'interface requiert de prendre en considération les gradients verticaux de charge et l'éventuelle anisotropie de l'aquifère. Cet article propose une méthode de calcul des

  14. Sunscreening fungal pigments influence the vertical gradient of pendulous lichens in boreal forest canopies.

    PubMed

    Färber, Leonie; Sølhaug, Knut Asbjorn; Esseen, Per-Anders; Bilger, Wolfgang; Gauslaa, Yngvar

    2014-06-01

    Pendulous lichens dominate canopies of boreal forests, with dark Bryoria species in the upper canopy vs. light Alectoria and Usnea species in lower canopy. These genera offer important ecosystem services such as winter forage for reindeer and caribou. The mechanism behind this niche separation is poorly understood. We tested the hypothesis that species-specific sunscreening fungal pigments protect underlying symbiotic algae differently against high light, and thus shape the vertical canopy gradient of epiphytes. Three pale species with the reflecting pigment usnic acid (Alectoria sarmentosa, Usnea dasypoga, U. longissima) and three with dark, absorbing melanins (Bryoria capillaris, B. fremontii, B. fuscescens) were compared. We subjected the lichens to desiccation stress with and without light, and assessed their performance with chlorophyll fluorescence. Desiccation alone only affected U. longissima. By contrast, light in combination with desiccation caused photoinhibitory damage in all species. Usnic lichens were significantly more susceptible to light during desiccation than melanic ones. Thus, melanin is a more efficient light-screening pigment than usnic acid. Thereby, the vertical gradient of pendulous lichens in forest canopies is consistent with a shift in type and functioning of sunscreening pigments, from high-light-tolerant Bryoria in the upper to susceptible Alectoria and Usnea in the lower canopy.

  15. Sensitivity of airborne fluorosensor measurements to linear vertical gradients in chlorophyll concentration

    NASA Technical Reports Server (NTRS)

    Venable, D. D.; Punjabi, A. R.; Poole, L. R.

    1984-01-01

    A semianalytic Monte Carlo radiative transfer simulation model for airborne laser fluorosensors has been extended to investigate the effects of inhomogeneities in the vertical distribution of phytoplankton concentrations in clear seawater. Simulation results for linearly varying step concentrations of chlorophyll are presented. The results indicate that statistically significant differences can be seen under certain conditions in the water Raman-normalized fluorescence signals between nonhomogeneous and homogeneous cases. A statistical test has been used to establish ranges of surface concentrations and/or verticl gradients in which calibration by surface samples would by inappropriate, and the results are discussed.

  16. Immersion and contact freezing experiments in the Mainz wind tunnel laboratory

    NASA Astrophysics Data System (ADS)

    Eppers, Oliver; Mayer, Amelie; Diehl, Karoline; Mitra, Subir; Borrmann, Stephan; Szakáll, Miklós

    2016-04-01

    Immersion and contact freezing are of outmost important ice nucleation processes in mixed phase clouds. Experimental studies are carried out in the Mainz vertical wind tunnel laboratory in order to characterize these nucleation processes for different ice nucleating particles (INP), such as for mineral dust or biological particles. Immersion freezing is investigated in our laboratory with two different experimental techniques, both attaining contact-free levitation of liquid droplets and cooling of the surrounding air down to about -25 °C. In an acoustic levitator placed in the cold room of our laboratory, drops with diameters of 2 mm are investigated. In the vertical air stream of the wind tunnel droplets with diameter of 700 micron are freely floated at their terminal velocities, simulating the flow conditions of the free atmosphere. Furthermore, the wind tunnel offers a unique platform for contact freezing experiments. Supercooled water droplets are floated in the vertical air stream at their terminal velocities and INP are injected into the tunnel air stream upstream of them. As soon as INP collides with the supercooled droplet the contact freezing is initiated. The first results of immersion and contact freezing experiments with cellulose particles both in the acoustic levitator and in the wind tunnel will be presented. Cellulose is considered as typical INP of biological origin and a macrotracer for plant debris. Nucleating properties of cellulose will be provided, mainly focusing on the temperature, INP concentration, and specific surface area dependences of the freezing processes. Direct comparison between the different experimental techniques (acoustic levitator and wind tunnel), as well as between nucleation modes (immersion and contact freezing) will be presented. The work is carried out within the framework of the German research unit INUIT.

  17. Environment vs. Plant Ontogeny: Arthropod Herbivory Patterns on European Beech Leaves along the Vertical Gradient of Temperate Forests in Central Germany

    PubMed Central

    Mantilla-Contreras, Jasmin

    2018-01-01

    Environmental and leaf trait effects on herbivory are supposed to vary among different feeding guilds. Herbivores also show variability in their preferences for plant ontogenetic stages. Along the vertical forest gradient, environmental conditions change, and trees represent juvenile and adult individuals in the understorey and canopy, respectively. This study was conducted in ten forests sites in Central Germany for the enrichment of canopy research in temperate forests. Arthropod herbivory of different feeding traces was surveyed on leaves of Fagus sylvatica Linnaeus (European beech; Fagaceae) in three strata. Effects of microclimate, leaf traits, and plant ontogenetic stage were analyzed as determining parameters for herbivory. The highest herbivory was caused by exophagous feeding traces. Herbivore attack levels varied along the vertical forest gradient for most feeding traces with distinct patterns. If differences of herbivory levels were present, they only occurred between juvenile and adult F. sylvatica individuals, but not between the lower and upper canopy. In contrast, differences of microclimate and important leaf traits were present between the lower and upper canopy. In conclusion, the plant ontogenetic stage had a stronger effect on herbivory than microclimate or leaf traits along the vertical forest gradient. PMID:29373542

  18. Optimum gradient of mountain paths.

    PubMed

    Minetti, A E

    1995-11-01

    By combining the experiment results of R. Margaria (Atti Accad. Naz. Lincei Memorie 7: 299-368, 1938), regarding the metabolic cost of gradient locomotion, together with recent insights on gait biomechanics, a prediction about the most economical gradient of mountain paths (approximately 25%) is obtained and interpreted. The pendulum-like mechanism of walking produces a waste of mechanical work against gravity within the gradient range of up to 15% (the overall efficiency is dominated by the low transmission efficiency), whereas for steeper values only the muscular efficiency is responsible for the (slight) metabolic change (per meter of vertical displacement) with respect to gradient. The speeds at the optimum gradient turned out to be approximately 0.65 m/s (+0.16 m/s vertical) and 1.50 m/s (-0.36 m/s vertical), for uphill and downhill walking, respectively, and the ascensional energy expenditure was 0.4 and 2.0 ml O2.kg body mass-1.vertical m-1 climbed or descended. When the metabolic power becomes a burden, as in high-altitude mountaineering, the optimum gradient should be reduced. A sample of real mountain path gradients, experimentally measured, mimics the obtained predictions.

  19. Echo-Planar Imaging for a 9.4 Tesla Vertical-Bore Superconducting Magnet Using an Unshielded Gradient Coil.

    PubMed

    Kodama, Nao; Kose, Katsumi

    2016-10-11

    Echo-planar imaging (EPI) sequences were developed for a 9.4 Tesla vertical standard bore (~54 mm) superconducting magnet using an unshielded gradient coil optimized for live mice imaging and a data correction technique with reference scans. Because EPI requires fast switching of intense magnetic field gradients, eddy currents were induced in the surrounding metallic materials, e.g., the room temperature bore, and this produced serious artifacts on the EPI images. We solved the problem using an unshielded gradient coil set of proper size (outer diameter = 39 mm, inner diameter = 32 mm) with time control of the current rise and reference scans. The obtained EPI images of a phantom and a plant sample were almost artifact-free and demonstrated the promise of our approach.

  20. Echo-Planar Imaging for a 9.4 Tesla Vertical-Bore Superconducting Magnet Using an Unshielded Gradient Coil

    PubMed Central

    KODAMA, Nao; KOSE, Katsumi

    2016-01-01

    Echo-planar imaging (EPI) sequences were developed for a 9.4 Tesla vertical standard bore (∼54 mm) superconducting magnet using an unshielded gradient coil optimized for live mice imaging and a data correction technique with reference scans. Because EPI requires fast switching of intense magnetic field gradients, eddy currents were induced in the surrounding metallic materials, e.g., the room temperature bore, and this produced serious artifacts on the EPI images. We solved the problem using an unshielded gradient coil set of proper size (outer diameter = 39 mm, inner diameter = 32 mm) with time control of the current rise and reference scans. The obtained EPI images of a phantom and a plant sample were almost artifact-free and demonstrated the promise of our approach. PMID:27001398

  1. On the dominant impact of vertical moisture gradient on mesoscale cloud cellular organization of stratocumulus

    NASA Astrophysics Data System (ADS)

    Zhou, X.; Ackerman, A. S.; Fridlind, A. M.; Kollias, P.

    2016-12-01

    Large-eddy simulations are performed to study the mechanisms of stratocumulus organization. Precipitation tends to increase horizontal cloud scales, but is not required for cloud mesoscale organization. A study of the terms in the prognostic equation for total water mixing ratio variance shows the critical impact of vertical moisture gradient on cloud scale. For precipitating clouds, the organization originates from the negative moisture gradient in the boundary layer resulting from evaporation of precipitation. This hypothesis is supported by simulations in which thermodynamics profiles are nudged to their initial well-mixed state, which reduces cloud scales. Cold pools effect are surprisingly found to respond to rather than determine the cloud mesoscale variability. For non-precipitating clouds, organization results from turbulent transport of moisture variance originating primarily from cloud top, where dry air is entrained into the boundary layer through convection driven by cloud top longwave (LW) cooling. Both LW cooling and a moisture gradient above cloud top are essential for the growth of mesoscale fluctuations.

  2. Mesoscale monitoring of the soil freeze/thaw boundary from orbital microwave radiometry

    NASA Technical Reports Server (NTRS)

    Dobson, Craig; Ulaby, Fawwaz T.; Zuerndorfer, Brian; England, Anthony W.

    1990-01-01

    A technique was developed for mapping the spatial extent of frozen soils from the spectral characteristics of the 10.7 to 37 GHz radiobrightness. Through computational models for the spectral radiobrightness of diurnally heated freesing soils, a distinctive radiobrightness signature was identified for frozen soils, and the signature was cast as a discriminant for unsupervised classification. In addition to large area images, local area spatial averages of radiobrightness were calculated for each radiobrightness channel at 7 meteorologic sites within the test region. Local area averages at the meteorologic sites were used to define the preliminary boundaries in the Freeze Indicator discriminate. Freeze Indicator images based upon Nimbus 7, Scanning Multichannel Microwave Radiometer (SMMR) data effectively map temporal variations in the freeze/thaw pattern for the northern Great Plains at the time scale of days. Diurnal thermal gradients have a small but measurable effect upon the SMMR spectral gradient. Scale-space filtering can be used to improve the spatial resolution of a freeze/thaw classified image.

  3. The imprints of bars on the vertical stellar population gradients of galactic bulges

    NASA Astrophysics Data System (ADS)

    Molaeinezhad, A.; Falcón-Barroso, J.; Martínez-Valpuesta, I.; Khosroshahi, H. G.; Vazdekis, A.; La Barbera, F.; Peletier, R. F.; Balcells, M.

    2017-05-01

    This is the second paper of a series aimed to study the stellar kinematics and population properties of bulges in highly inclined barred galaxies. In this work, we carry out a detailed analysis of the stellar age, metallicity and [Mg/Fe] of 28 highly inclined (I > 65°) disc galaxies, from S0 to S(B)c, observed with the SAURON integral-field spectrograph. The sample is divided into two clean samples of barred and unbarred galaxies, on the basis of the correlation between the stellar velocity and h3 profiles, as well as the level of cylindrical rotation within the bulge region. We find that while the mean stellar age, metallicity and [Mg/Fe] in the bulges of barred and unbarred galaxies are not statistically distinct, the [Mg/Fe] gradients along the minor axis (away from the disc) of barred galaxies are significantly different than those without bars. For barred galaxies, stars that are vertically further away from the mid-plane are in general more [Mg/Fe]-enhanced and thus the vertical gradients in [Mg/Fe] for barred galaxies are mostly positive, while for unbarred bulges the [Mg/Fe] profiles are typically negative or flat. This result, together with the old populations observed in the barred sample, indicates that bars are long-lasting structures, and therefore are not easily destroyed. The marked [Mg/Fe] differences with the bulges of unbarred galaxies indicate that different formation/evolution scenarios are required to explain their build-up, and emphasizes the role of bars in redistributing stellar material in the bulge-dominated regions.

  4. Nitrate and dissolved organic carbon mobilization in response to soil freezing variability

    Treesearch

    Colin B. Fuss; Charles T. Driscoll; Peter M. Groffman; John L. Campbell; Lynn M. Christenson; Timothy J. Fahey; Melany C. Fisk; Myron J. Mitchell; Pamela H. Templer; Jorge Durán; Jennifer L. Morse

    2016-01-01

    Reduced snowpack and associated increases in soil freezing severity resulting from winter climate change have the potential to disrupt carbon (C) and nitrogen (N) cycling in soils. We used a natural winter climate gradient based on elevation and aspect in a northern hardwood forest to examine the effects of variability in soil freezing depth, duration, and frequency on...

  5. Gravity and gravity gradient changes caused by a point dislocation

    NASA Astrophysics Data System (ADS)

    Huang, Jian-Liang; Li, Hui; Li, Rui-Hao

    1995-02-01

    In this paper we studied gravitational potential, gravity and its gradient changes, which are caused by a point dislocation, and gave the concise mathematical deduction with definite physical implication in dealing with the singular integral at a seismic source. We also analysed the features of the fields of gravity and gravity gradient, gravity-vertical-displacement gradient. The conclusions are: (1) Gravity and gravity gradient changes are very small with the change of vertical position; (2) Gravity change is much greater than the gravity gradient change which is not so distinct; (3) The gravity change due to redistribution of mass accounts for 10 50 percent of the total gravity change caused by dislocation. The signs (positive or negative) of total gravity change and vertical displacement are opposite each other at the same point for strike slip and dip slip; (4) Gravity-vertical-displacement-gradient is not constant; it manifests a variety of patterns for different dislocation models; (5) Gravity-vertical-displacement-gradient is approximately equal to apparent gravity-vertical-displacement-gradient.

  6. Vertical two-phase flow regimes and pressure gradients under the influence of SDS surfactant

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Duangprasert, Tanabordee; Sirivat, Anuvat; Siemanond, Kitipat

    2008-01-15

    Two-phase gas/liquid flows in vertical pipes have been systematically investigated. Water and SDS surfactant solutions at various concentrations were used as the working fluids. In particular, we focus our work on the influence of surfactant addition on the flow regimes, the corresponding pressure gradients, and the bubble sizes and velocity. Adding the surfactant lowers the air critical Reynolds numbers for the bubble-slug flow and the slug flow transitions. The pressure gradients of SDS solutions are lower than those of pure water especially in the slug flow and the slug-churn flow regimes, implying turbulent drag reduction. At low Re{sub air}, themore » bubble sizes of the surfactant solution are lower than those of pure water due to the increase in viscosity. With increasing and at high Re{sub air}, the bubble sizes of the SDS solution become greater than those of pure water which is attributed to the effect of surface tension. (author)« less

  7. Gravity Gradient Tensor of Arbitrary 3D Polyhedral Bodies with up to Third-Order Polynomial Horizontal and Vertical Mass Contrasts

    NASA Astrophysics Data System (ADS)

    Ren, Zhengyong; Zhong, Yiyuan; Chen, Chaojian; Tang, Jingtian; Kalscheuer, Thomas; Maurer, Hansruedi; Li, Yang

    2018-03-01

    During the last 20 years, geophysicists have developed great interest in using gravity gradient tensor signals to study bodies of anomalous density in the Earth. Deriving exact solutions of the gravity gradient tensor signals has become a dominating task in exploration geophysics or geodetic fields. In this study, we developed a compact and simple framework to derive exact solutions of gravity gradient tensor measurements for polyhedral bodies, in which the density contrast is represented by a general polynomial function. The polynomial mass contrast can continuously vary in both horizontal and vertical directions. In our framework, the original three-dimensional volume integral of gravity gradient tensor signals is transformed into a set of one-dimensional line integrals along edges of the polyhedral body by sequentially invoking the volume and surface gradient (divergence) theorems. In terms of an orthogonal local coordinate system defined on these edges, exact solutions are derived for these line integrals. We successfully derived a set of unified exact solutions of gravity gradient tensors for constant, linear, quadratic and cubic polynomial orders. The exact solutions for constant and linear cases cover all previously published vertex-type exact solutions of the gravity gradient tensor for a polygonal body, though the associated algorithms may differ in numerical stability. In addition, to our best knowledge, it is the first time that exact solutions of gravity gradient tensor signals are derived for a polyhedral body with a polynomial mass contrast of order higher than one (that is quadratic and cubic orders). Three synthetic models (a prismatic body with depth-dependent density contrasts, an irregular polyhedron with linear density contrast and a tetrahedral body with horizontally and vertically varying density contrasts) are used to verify the correctness and the efficiency of our newly developed closed-form solutions. Excellent agreements are obtained

  8. Bulk Crystal Growth of Piezoelectric PMN-PT Crystals Using Gradient Freeze Technique for Improved SHM Sensors

    NASA Technical Reports Server (NTRS)

    Aggarwal, Mohan D.; Kochary, F.; Penn, Benjamin G.; Miller, Jim

    2007-01-01

    There has been a growing interest in recent years in lead based perovskite ferroelectric and relaxor ferroelectric solid solutions because of their excellent dielectric, piezoelectric and electrostrictive properties that make them very attractive for various sensing, actuating and structural health monitoring (SHM) applications. We are interested in the development of highly sensitive and efficient PMN-PT sensors based on large single crystals for the structural health monitoring of composite materials that may be used in future spacecrafts. Highly sensitive sensors are needed for detection of defects in these materials because they often tend to fail by distributed and interacting damage modes and much of the damage occurs beneath the top surface of the laminate and not detectable by visual inspection. Research is being carried out for various combinations of solid solutions for PMN-PT piezoelectric materials and bigger size crystals are being sought for improved sensor applications. Single crystals of this material are of interest for sensor applications because of their high piezoelectric coefficient (d33 greater than 1700 pC/N) and electromechanical coefficients (k33 greater than 0.90). For comparison, the commonly used piezoelectric ceramic lead zirconate titanate (PZT) has a d33 of about 600 pC/N and electromechanical coefficients k33 of about 0.75. At the present time, these piezoelectric relaxor crystals are grown by high temperature flux growth method and the size of these crystals are rather small (3x4x5 mm(exp 3). In the present paper, we have attempted to grow bulk single crystals of PMN-PT in a 2 inch diameter platinum crucible and successfully grown a large size crystal of 67%PMN-33%PT using the vertical gradient freeze technique with no flux. Piezoelectric properties of the grown crystals are investigated. PMN-PT plates show excellent piezoelectric properties. Samples were poled under an applied electric field of 5 kV/cm. Dielectric properties at a

  9. Strong temperature gradients and vertical wind shear on MLT region associated to instability source at 23°S

    NASA Astrophysics Data System (ADS)

    Andrioli, V. F.; Batista, P. P.; Xu, Jiyao; Yang, Guotao; Chi, Wang; Zhengkuan, Liu

    2017-04-01

    Na lidar temperature measurements were taken successfully from 2007 to 2009 in the mesopause region over São José dos Campos (23.1°S, 45.9°W). Strong gradients on these vertical temperature profiles are often observed. A simple theoretical study has shown that temperature gradient of at least -8 K/km is required concurrently with the typical tidal wind shear in order to generate dynamical instability in the MLT region. We have studied vertical shear in horizontal wind related to atmospheric tides, inferred by meteor radar, with the aim of analyzing instability occurrence. These wind measurements were taken from an all-sky meteor radar at Cachoeira Paulista (22.7°S, 45°W). Two years of simultaneous data, wind and temperature, were used in this analysis which represent 79 days, totalizing 589 h of simultaneous observations. We realize that the condition for the local Richardson number (Ri) dropping below the critical value of instability (Ri < 0.25) is often reached in 98% of the analyzed cases. The mean probabilities for occurrence of convective and dynamical instabilities, in the altitude region between 82 and 98 km, were observed to be about 3% and 17.5%, respectively. Additionally, vertical distribution of these probabilities has revealed a weak occurrence of dynamical instability around 90 km, and this fact can be related to the double mesopause typically observed in this site.

  10. Constraints on Southern Ocean CO2 Fluxes and Seasonality from Atmospheric Vertical Gradients Observed on Multiple Airborne Campaigns

    NASA Astrophysics Data System (ADS)

    McKain, K.; Sweeney, C.; Stephens, B. B.; Long, M. C.; Jacobson, A. R.; Basu, S.; Chatterjee, A.; Weir, B.; Wofsy, S. C.; Atlas, E. L.; Blake, D. R.; Montzka, S. A.; Stern, R.

    2017-12-01

    The Southern Ocean plays an important role in the global carbon cycle and climate system, but net CO2 flux into the Southern Ocean is difficult to measure and model because it results from large opposing and seasonally-varying fluxes due to thermal forcing, biological uptake, and deep-water mixing. We present an analysis to constrain the seasonal cycle of net CO2 exchange with the Southern Ocean, and the magnitude of summer uptake, using the vertical gradients in atmospheric CO2 observed during three aircraft campaigns in the southern polar region. The O2/N2 Ratio and CO2 Airborne Southern Ocean Study (ORCAS) was an airborne campaign that intensively sampled the atmosphere at 0-13 km altitude and 45-75 degrees south latitude in the austral summer (January-February) of 2016. The global airborne campaigns, the HIAPER Pole-to-Pole Observations (HIPPO) study and the Atmospheric Tomography Mission (ATom), provide additional measurements over the Southern Ocean from other seasons and multiple years (2009-2011, 2016-2017). Derivation of fluxes from measured vertical gradients requires robust estimates of the residence time of air in the polar tropospheric domain, and of the contribution of long-range transport from northern latitudes outside the domain to the CO2 gradient. We use diverse independent approaches to estimate both terms, including simulations using multiple transport and flux models, and observed gradients of shorter-lived tracers with specific sources regions and well-known loss processes. This study demonstrates the utility of aircraft profile measurements for constraining large-scale air-sea fluxes for the Southern Ocean, in contrast to those derived from the extrapolation of sparse ocean and atmospheric measurements and uncertain flux parameterizations.

  11. Vertical variation of a black soil's properties in response to freeze-thaw cycles and its links to shift of microbial community structure.

    PubMed

    Han, Ziming; Deng, Mingwen; Yuan, Anqi; Wang, Jiahui; Li, Hao; Ma, Jincai

    2018-06-01

    Soil freeze-thaw cycles (FTCs) change soil physical, chemical, and biological properties, however information regarding their vertical variations in response to FTCs is limited. In this work, black soil (silty loam) packed soil columns were exposed to 8 FTCs, and soil properties were determined for each of vertical layer of soil columns. The results revealed that after FTCs treatment, moisture and electrical conductivity (EC) salinity tended to increase in upper soil layers. Increments of ammonium nitrogen (NH 4 + -N) and nitrate nitrogen (NO 3 - -N) in top layers (0-10cm) were greater than those in other layers, and increments of water soluble organic carbon (WSOC) and decrease of microbial biomass carbon (MBC) in middle layers (10-20cm) were greater than those in both ends. Overall, microbial community structure was mainly influenced by soil physical properties (moisture and EC) and chemical properties (pH and WSOC). For bacterial (archaeal) and fungal communities, soil physical properties, chemical properties and their interaction explained 79.73% and 82.66% of total variation, respectively. Our results provided insights into the vertical variation of soil properties caused by FTCs, and such variation had a major impact on the change of structure and composition of soil bacterial and fungal communities. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Use of sinkhole and specific capacity distributions to assess vertical gradients in a karst aquifer

    USGS Publications Warehouse

    McCoy, K.J.; Kozar, M.D.

    2008-01-01

    The carbonate-rock aquifer in the Great Valley, West Virginia, USA, was evaluated using a database of 687 sinkholes and 350 specific capacity tests to assess structural, lithologic, and topographic influences on the groundwater flow system. The enhanced permeability of the aquifer is characterized in part by the many sinkholes, springs, and solutionally enlarged fractures throughout the valley. Yet, vertical components of subsurface flow in this highly heterogeneous aquifer are currently not well understood. To address this problem, this study examines the apparent relation between geologic features of the aquifer and two spatial indices of enhanced permeability attributed to aquifer karstification: (1) the distribution of sinkholes and (2) the occurrence of wells with relatively high specific capacity. Statistical results indicate that sinkholes (funnel and collapse) occur primarily along cleavage and bedding planes parallel to subparallel to strike where lateral or downward vertical gradients are highest. Conversely, high specific capacity values are common along prominent joints perpendicular or oblique to strike. The similarity of the latter distribution to that of springs suggests these fractures are areas of upward-convergent flow. These differences between sinkhole and high specific capacity distributions suggest vertical flow components are primarily controlled by the orientation of geologic structure and associated subsurface fracturing. ?? 2007 Springer-Verlag.

  13. Effect of Latent Heat Released by Freezing Droplets during Frost Wave Propagation.

    PubMed

    Chavan, Shreyas; Park, Deokgeun; Singla, Nitish; Sokalski, Peter; Boyina, Kalyan; Miljkovic, Nenad

    2018-05-21

    Frost spreads on nonwetting surfaces during condensation frosting via an interdroplet frost wave. When a supercooled condensate water droplet freezes on a hydrophobic or superhydrophobic surface, neighboring droplets still in the liquid phase begin to evaporate. Two possible mechanisms govern the evaporation of neighboring water droplets: (1) The difference in saturation pressure of the water vapor surrounding the liquid and frozen droplets induces a vapor pressure gradient, and (2) the latent heat released by freezing droplets locally heats the substrate, leading to evaporation of nearby droplets. The relative significance of these two mechanisms is still not understood. Here, we study the significance of the latent heat released into the substrate by freezing droplets, and its effect on adjacent droplet evaporation, by studying the dynamics of individual water droplet freezing on aluminum-, copper-, and glass-based hydrophobic and superhydrophobic surfaces. The latent heat flux released into the substrate was calculated from the measured droplet sizes and the respective freezing times ( t f ), defined as the time from initial ice nucleation within the droplet to complete droplet freezing. To probe the effect of latent heat release, we performed three-dimensional transient finite element simulations showing that the transfer of latent heat to neighboring droplets is insignificant and accounts for a negligible fraction of evaporation during microscale frost wave propagation. Furthermore, we studied the effect of substrate thermal conductivity on the transfer of latent heat transfer to neighboring droplets by investigating the velocity of ice bridge formation. The velocity of the ice bridge was independent of the substrate thermal conductivity, indicating that adjacent droplet evaporation during condensation frosting is governed solely by vapor pressure gradients. This study not only provides key insights into the individual droplet freezing process but also

  14. Highly efficient organic solar cells with improved vertical donor-acceptor compositional gradient via an inverted off-center spinning method

    DOE PAGES

    Huang, Jiang; Carpenter, Joshua H.; Li, Chang -Zhi; ...

    2015-12-02

    A novel, yet simple solution fabrication technique to address the trade-off between photocurrent and fill factor in thick bulk heterojunction organic solar cells is described. Lastly, the inverted off-center spinning technique promotes a vertical gradient of the donor–acceptor phase-separated morphology, enabling devices with near 100% internal quantum efficiency and a high power conversion efficiency of 10.95%.

  15. Do Vertical Gradients in Soil Environmental Conditions Regulate Exudation Rates from Peatland Vegetation?

    NASA Astrophysics Data System (ADS)

    Proctor, C.; He, Y.

    2017-12-01

    Deposition of carbon belowground via the root exudation pathway is the net of root-borne efflux and influx processes. For select exudates, root have a remarkable ability to actively recapture lost compounds, suggesting that influx mechanisms regulate exudation. However, roots are not the sole sink for root effluxed carbon. Roots compete with solute sorption and microbial uptake, whom are regulated by a unique set of soil environmental conditions. Peatland soil features stark vertical gradients in their physical, chemical, biological, and hydrological properties, which has downstream implications for the relative competitive ability of each actor in root-soil-microbial interactions. This study developed a single root exudate model using the Barber-Cushman approach to examine the radial accumulation of exudates in simulated peatland soil with vertical gradients. The model simulated efflux, influx, solute diffusion, solute mineralization and solid phase sorption mechanisms as depth dependent on bulk density, porosity, tortuosity, buffer power, temperature, and microbial biomass. Deeper peat soil reduced the porosity that permits solute transport, increased tortuosity which lowered the effective diffusion rate, increased solute-solid sorption, and reduced microbial mineralization of effluxed compounds. Slower mineralization rates were partially juxtaposed by increases in sorption, albeit the net removal of effluxed compounds was lower, leading to a larger amount of exudates to remain in the rhizosphere around deeper roots. Increase in the solid phase, and its subsequent constriction of solute migration, lead to a higher accumulation of effluxed compounds on the rhizoplane, up to 1.23x higher than shallow soil. Subsequently, influx mechanisms captured a larger fraction of effluxed compounds (69.06% at -10cm versus 84.8% at -80 cm), reducing net exudation rates from 0.641 to 0.315 nmol cm-1 hr-1 between -10 and -80cm depths. These results suggest that localized

  16. Solid-Phase Fe Speciation along the Vertical Redox Gradients in Floodplains using XAS and Mössbauer Spectroscopies.

    PubMed

    Chen, Chunmei; Kukkadapu, Ravi K; Lazareva, Olesya; Sparks, Donald L

    2017-07-18

    Properties of Fe minerals are poorly understood in natural soils and sediments with variable redox conditions. In this study, we combined 57 Fe Mössbauer and Fe K-edge X-ray absorption spectroscopic (XAS) techniques to assess solid-phase Fe speciation along the vertical redox gradients of floodplains, which exhibited a succession of oxic, anoxic, and suboxic-oxic zones with increasing depth along the vertical profiles. The incised stream channel is bounded on the east by a narrow floodplain and a steep hillslope, and on the west by a broad floodplain. In the eastern floodplain, the anoxic conditions at the intermediate horizon (55-80 cm) coincided with lower Fe(III)-oxides (particularly ferrihydrite), in concurrence with a greater reduction of phyllosilicates(PS)-Fe(III) to PS-Fe(II), relative to the oxic near-surface and sandy gravel layers. In addition, the anoxic conditions in the eastern floodplain coincided with increased crystallinity of goethite, relative to the oxic layers. In the most reduced intermediate sediments at 80-120 cm of the western floodplain, no Fe(III)-oxides were detected, concurrent with the greatest PS-Fe(III) reduction (PS-Fe(II)/Fe(III) ratio ≈ 1.2 (Mössbauer) or 0.8 (XAS)). In both oxic near-surface horizon and oxic-suboxic gravel aquifers beneath the soil horizons, Fe(III)-oxides were mainly present as ferrihydrite with a much less amount of goethite, which preferentially occurred as nanogoethite or Al/Si-substituted goethite. Ferrihydrite with varying crystallinity or impurities such as organic matter, Al or Si, persisted under suboxic-oxic conditions in the floodplain. This study indicates that vertical redox gradients exert a major control on the quantity and speciation of Fe(III) oxides as well as the oxidation state of structural Fe in PS, which could significantly affect nutrient cycling and carbon (de)stabilization.

  17. Giant panda (Ailuropoda melanoleuca) sperm morphometry and function after repeated freezing and thawing.

    PubMed

    Santiago-Moreno, J; Esteso, M C; Pradiee, J; Castaño, C; Toledano-Díaz, A; O'Brien, E; Lopez-Sebastián, A; Martínez-Nevado, E; Delclaux, M; Fernández-Morán, J; Zhihe, Z

    2016-05-01

    This work examines the effects of subsequent cycles of freezing-thawing on giant panda (Ailuropoda melanoleuca) sperm morphometry and function, and assesses whether density-gradient centrifugation (DGC) can increase the number of freezing-thawing cycles this sperm can withstand. A sperm sample was collected by electroejaculation from a mature giant panda and subjected to five freezing-thawing cycles. Although repeated freezing-thawing negatively affected (P < 0.05) sperm motility and membrane integrity, in both nonselected and DCG-selected sperm samples, >60% of the sperm cells in both treatments showed acrosome integrity even after the fifth freezing cycle. In fresh semen, the sperm head length was 4.7 μm, the head width 3.6 μm, area 14.3 μm(2) and perimeter length 14.1 μm. The present results suggest that giant panda sperm trends to be resistant to repeated freezing-thawing, even without DGC selection. © 2015 Blackwell Verlag GmbH.

  18. Predicting nitrogen flux along a vertical canopy gradient in a mixed conifer forest stand of the San Bernardino Mountains in California

    Treesearch

    Michael J. Arbaugh; Andrzej Bytnerowicz; Mark E. Fenn

    1998-01-01

    A 3-year study of nitrogenous (N) air pollution deposition to ponderosa pine (Pinus ponderosa Dougl. ex. Laws.) seedlings along a mature tree vertical canopy gradient was conducted in the mixed conifer forest of the San Bernardino Mountains of southern California. Concentrations of nitric acid vapor (HNO3), particulate nitrate...

  19. Repeated vitrification/warming of human sperm gives better results than repeated slow programmable freezing

    PubMed Central

    Vutyavanich, Teraporn; Lattiwongsakorn, Worashorn; Piromlertamorn, Waraporn; Samchimchom, Sudarat

    2012-01-01

    In this study, we compared the effects of repeated freezing/thawing of human sperm by our in-house method of rapid freezing with slow programmable freezing. Sperm samples from 11 normozoospermic subjects were processed through density gradients and divided into three aliquots: non-frozen, rapid freezing and slow programmable freezing. Sperm in the rapid freezing group had better motility and viability than those in the slow freezing group (P<0.01) after the first, second and third cycles of freezing/thawing, but there was no difference in morphology. In the second experiment, rapid freezing was repeated three times in 20 subjects. The samples from each thawing cycle were evaluated for DNA fragmentation using the alkaline comet assay. DNA fragmentation began to increase considerably after the second cycle of freezing/thawing, but to a level that was not clinically important. In the third experiment, rapid freezing was done repeatedly in 10 subjects, until no motile sperm were observed after thawing. The median number of repeated freezing/thawing that yielded no motile sperm was seven (range: 5–8, mean: 6.8). In conclusion, we demonstrated that repeated freezing/thawing of processed semen using our rapid freezing method gave better results than standard slow programmable freezing. This method can help maximize the usage of precious cryopreserved sperm samples in assisted reproduction technology. PMID:23064685

  20. Thermodynamical effects accompanied freezing of two water layers separated by sea ice sheet

    NASA Astrophysics Data System (ADS)

    Bogorodsky, Petr; Marchenko, Aleksey

    2014-05-01

    The process of melt pond freezing is very important for generation of sea ice cover thermodynamic and mass balance during winterperiod. However, due to significant difficulties of field measurements the available data of model estimations still have no instrumental confirmation. In May 2009 the authors carried out laboratory experiment on freezing of limited water volume in the University Centre in Svalbard ice tank. In the course of experiment fresh water layer of 27.5 cm thickness at freezing point poured on the 24 cm sea ice layer was cooled during 50 hours at the temperature -10º C and then once again during 60 hours at -20º C. For revealing process typical characteristics the data of continuous measurements of temperature and salinity in different phases were compared with data of numerical computations obtained with thermodynamic model which was formulated in the frames of 1-D equation system (infinite extension of water freezing layer) and adapted to laboratory conditions. The known surprise of the experiment became proximity of calculated and measured estimates of process dynamics that confirmed the adequacy of the problem mathematical statement (excluding probably process finale stage). This effect can be explained by formation of cracks on the upper layer of ice at sharp decreases of air temperature, which temporary compensated hydrostatic pressure growth during freezing of closed water volume. Another compensated mechanism can be migration of brine through the lower layer of ice under influence of vertical pressure gradient and also rejection of gas dissolved in water which increased its compressibility. During 110 hours cooling thickness of water layer between ice layers reduced approximately to 2 cm. According to computations this layer is not chilled completely but keeps as thin brine interlayer within ice body whose thickness (about units of mm) is determined by temperature fluctuations of cooled surface. Nevertheless, despite good coincidence of

  1. Mangrove expansion and contraction at a poleward range limit: climate extremes and land-ocean temperature gradients.

    PubMed

    Osland, Michael J; Day, Richard H; Hall, Courtney T; Brumfield, Marisa D; Dugas, Jason L; Jones, William R

    2017-01-01

    Within the context of climate change, there is a pressing need to better understand the ecological implications of changes in the frequency and intensity of climate extremes. Along subtropical coasts, less frequent and warmer freeze events are expected to permit freeze-sensitive mangrove forests to expand poleward and displace freeze-tolerant salt marshes. Here, our aim was to better understand the drivers of poleward mangrove migration by quantifying spatiotemporal patterns in mangrove range expansion and contraction across land-ocean temperature gradients. Our work was conducted in a freeze-sensitive mangrove-marsh transition zone that spans a land-ocean temperature gradient in one of the world's most wetland-rich regions (Mississippi River Deltaic Plain; Louisiana, USA). We used historical air temperature data (1893-2014), alternative future climate scenarios, and coastal wetland coverage data (1978-2011) to investigate spatiotemporal fluctuations and climate-wetland linkages. Our analyses indicate that changes in mangrove coverage have been controlled primarily by extreme freeze events (i.e., air temperatures below a threshold zone of -6.3 to -7.6°C). We expect that in the past 121 yr, mangrove range expansion and contraction has occurred across land-ocean temperature gradients. Mangrove resistance, resilience, and dominance were all highest in areas closer to the ocean where temperature extremes were buffered by large expanses of water and saturated soil. Under climate change, these areas will likely serve as local hotspots for mangrove dispersal, growth, range expansion, and displacement of salt marsh. Collectively, our results show that the frequency and intensity of freeze events across land-ocean temperature gradients greatly influences spatiotemporal patterns of range expansion and contraction of freeze-sensitive mangroves. We expect that, along subtropical coasts, similar processes govern the distribution and abundance of other freeze

  2. Mangrove expansion and contraction at a poleward range limit: Climate extremes and land-ocean temperature gradients

    USGS Publications Warehouse

    Osland, Michael J.; Day, Richard H.; Hall, Courtney T.; Brumfield, Marisa D; Dugas, Jason; Jones, William R.

    2017-01-01

    Within the context of climate change, there is a pressing need to better understand the ecological implications of changes in the frequency and intensity of climate extremes. Along subtropical coasts, less frequent and warmer freeze events are expected to permit freeze-sensitive mangrove forests to expand poleward and displace freeze-tolerant salt marshes. Here, our aim was to better understand the drivers of poleward mangrove migration by quantifying spatiotemporal patterns in mangrove range expansion and contraction across land-ocean temperature gradients. Our work was conducted in a freeze-sensitive mangrove-marsh transition zone that spans a land-ocean temperature gradient in one of the world's most wetland-rich regions (Mississippi River Deltaic Plain; Louisiana, USA). We used historical air temperature data (1893-2014), alternative future climate scenarios, and coastal wetland coverage data (1978-2011) to investigate spatiotemporal fluctuations and climate-wetland linkages. Our analyses indicate that changes in mangrove coverage have been controlled primarily by extreme freeze events (i.e., air temperatures below a threshold zone of -6.3 to -7.6 °C). We expect that in the past 121 years, mangrove range expansion and contraction has occurred across land-ocean temperature gradients. Mangrove resistance, resilience, and dominance were all highest in areas closer to the ocean where temperature extremes were buffered by large expanses of water and saturated soil. Under climate change, these areas will likely serve as local hotspots for mangrove dispersal, growth, range expansion, and displacement of salt marsh. Collectively, our results show that the frequency and intensity of freeze events across land-ocean temperature gradients greatly influences spatiotemporal patterns of range expansion and contraction of freeze-sensitive mangroves. We expect that, along subtropical coasts, similar processes govern the distribution and abundance of other freeze

  3. Microgravimetry and the Measurement and Application of Gravity Gradients,

    DTIC Science & Technology

    1980-06-01

    Neumann, R., 1972, High precision gravimetry--recent develop- ments: Report to Paris Commission of E.A.E.G., Compagnie Generale de Geophysique , Massy...experimentation on vertical gradient: Compagnie Generale de Geophysique , Massy, France. 12. Fajklewicz, Z. J., 1976, Gravity vertical gradient

  4. Temperature and flow measurements on near-freezing aviation fuels in a wing-tank model

    NASA Technical Reports Server (NTRS)

    Friedman, R.; Stockemer, F. J.

    1980-01-01

    Freezing behavior, pumpability, and temperature profiles for aviation turbine fuels were measured in a 190-liter tank chilled to simulate internal temperature gradients encountered in commercial airplane wing tanks. When the bulk of the fuel was above the specification freezing point, pumpout of the fuel removed all fuel except a layer adhering to the bottom chilled surfaces, and the unpumpable fraction depended on the fuel temperature near these surfaces. When the bulk of the fuel was at or below the freezing point, pumpout ceased when solids blocked the pump inlet, and the unpumpable fraction depended on the overall average temperature.

  5. Shadowgraph Study of Gradient Driven Fluctuations

    NASA Technical Reports Server (NTRS)

    Cannell, David; Nikolaenko, Gennady; Giglio, Marzio; Vailati, Alberto; Croccolo, Fabrizio; Meyer, William

    2002-01-01

    A fluid or fluid mixture, subjected to a vertical temperature and/or concentration gradient in a gravitational field, exhibits greatly enhanced light scattering at small angles. This effect is caused by coupling between the vertical velocity fluctuations due to thermal energy and the vertically varying refractive index. Physically, small upward or downward moving regions will be displaced into fluid having a refractive index different from that of the moving region, thus giving rise to the enhanced scattering. The scattered intensity is predicted to vary with scattering wave vector q, as q(sup -4), for sufficiently large q, but the divergence is quenched by gravity at small q. In the absence of gravity, the long wavelength fluctuations responsible for the enhanced scattering are predicted to grow until limited by the sample dimensions. It is thus of interest to measure the mean-squared amplitude of such fluctuations in the microgravity environment for comparison with existing theory and ground based measurements. The relevant wave vectors are extremely small, making traditional low-angle light scattering difficult or impossible because of stray elastically scattered light generated by optical surfaces. An alternative technique is offered by the shadowgraph method, which is normally used to visualize fluid flows, but which can also serve as a quantitative tool to measure fluctuations. A somewhat novel shadowgraph apparatus and the necessary data analysis methods will be described. The apparatus uses a spatially coherent, but temporally incoherent, light source consisting of a super-luminescent diode coupled to a single-mode optical fiber in order to achieve extremely high spatial resolution, while avoiding effects caused by interference of light reflected from the various optical surfaces that are present when using laser sources. Results obtained for a critical mixture of aniline and cyclohexane subjected to a vertical temperature gradient will be presented. The

  6. Analytical solution and numerical simulation of the liquid nitrogen freezing-temperature field of a single pipe

    NASA Astrophysics Data System (ADS)

    Cai, Haibing; Xu, Liuxun; Yang, Yugui; Li, Longqi

    2018-05-01

    Artificial liquid nitrogen freezing technology is widely used in urban underground engineering due to its technical advantages, such as simple freezing system, high freezing speed, low freezing temperature, high strength of frozen soil, and absence of pollution. However, technical difficulties such as undefined range of liquid nitrogen freezing and thickness of frozen wall gradually emerge during the application process. Thus, the analytical solution of the freezing-temperature field of a single pipe is established considering the freezing temperature of soil and the constant temperature of freezing pipe wall. This solution is then applied in a liquid nitrogen freezing project. Calculation results show that the radius of freezing front of liquid nitrogen is proportional to the square root of freezing time. The radius of the freezing front also decreases with decreased the freezing temperature, and the temperature gradient of soil decreases with increased distance from the freezing pipe. The radius of cooling zone in the unfrozen area is approximately four times the radius of the freezing front. Meanwhile, the numerical simulation of the liquid nitrogen freezing-temperature field of a single pipe is conducted using the Abaqus finite-element program. Results show that the numerical simulation of soil temperature distribution law well agrees with the analytical solution, further verifies the reliability of the established analytical solution of the liquid nitrogen freezing-temperature field of a single pipe.

  7. Accurate pressure gradient calculations in hydrostatic atmospheric models

    NASA Technical Reports Server (NTRS)

    Carroll, John J.; Mendez-Nunez, Luis R.; Tanrikulu, Saffet

    1987-01-01

    A method for the accurate calculation of the horizontal pressure gradient acceleration in hydrostatic atmospheric models is presented which is especially useful in situations where the isothermal surfaces are not parallel to the vertical coordinate surfaces. The present method is shown to be exact if the potential temperature lapse rate is constant between the vertical pressure integration limits. The technique is applied to both the integration of the hydrostatic equation and the computation of the slope correction term in the horizontal pressure gradient. A fixed vertical grid and a dynamic grid defined by the significant levels in the vertical temperature distribution are employed.

  8. Mapping freeze/thaw boundaries with SMMR data

    NASA Technical Reports Server (NTRS)

    Zuerndorfer, B. W.; England, A. W.; Dobson, M. C.; Ulaby, F. T.

    1989-01-01

    Nimbus 7 Scanning Multichannel Microwave Radiometer (SMMR) data are used to map daily freeze/thaw patterns in the upper Midwest for the Fall of 1984. The combination of a low 37 GHz radiobrightness and a negative 10.7, 18, and 37 GHz spectral gradient, Partial Derivative of Tb with Respect to f, appears to be an effective discriminant for classifying soil as frozen or thawed. The 37 GHz emissivity is less sensitive to soil moisture than are the lower frequency emissivities so that the 37 GHz radiobrightness appears to track soil surface temperature relatively well. The negative gradient for frozen ground is a consequence of volume scatter darkening at shorter microwave wavelengths. This shorter wavelength darkening is not seen in thawed moist soils.

  9. Capitalizing Resolving Power of Density Gradient Ultracentrifugation by Freezing and Precisely Slicing Centrifuged Solution: Enabling Identification of Complex Proteins from Mitochondria by Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

    PubMed Central

    Yu, Haiqing; Lu, Joann J.; Rao, Wei

    2016-01-01

    Density gradient centrifugation is widely utilized for various high purity sample preparations, and density gradient ultracentrifugation (DGU) is often used for more resolution-demanding purification of organelles and protein complexes. Accurately locating different isopycnic layers and precisely extracting solutions from these layers play a critical role in achieving high-resolution DGU separations. In this technique note, we develop a DGU procedure by freezing the solution rapidly (but gently) after centrifugation to fix the resolved layers and by slicing the frozen solution to fractionate the sample. Because the thickness of each slice can be controlled to be as thin as 10 micrometers, we retain virtually all the resolution produced by DGU. To demonstrate the effectiveness of this method, we fractionate complex V from HeLa mitochondria using a conventional technique and this freezing-slicing (F-S) method. The comparison indicates that our F-S method can reduce complex V layer thicknesses by ~40%. After fractionation, we analyze complex V proteins directly on a matrix assisted laser desorption/ionization, time-of-flight mass spectrometer. Twelve out of fifteen subunits of complex V are positively identified. Our method provides a practical protocol to identify proteins from complexes, which is useful to investigate biomolecular complexes and pathways in various conditions and cell types. PMID:27668122

  10. Leachate Properties and Cadmium Migration Through Freeze-thaw Treated Soil Columns.

    PubMed

    Xu, Meng; Zheng, Yue; Chen, Weiwei; Mao, Na; Guo, Ping

    2017-01-01

    Soil column leaching experiments were conducted to study the effects of multiple freeze-thaw cycles on the vertical migration of cadmium (Cd). Three Cd-spiked leaching solutions of different properties were derived from snowmelt, sludge, and straw, designated as B, W and J, respectively. The leaching solutions varied in dissolved organic matter (DOM) concentrations in the order of J > W > B. Changes in leachate properties and Cd concentration were observed. The results showed that pH values of all the leachate solutions through freeze-thaw treated soil columns were higher than those of leachates through unfrozen soils. However, electrical conductivity (EC) values decreased compared with leachates in unfrozen treated soil columns. Although the concentrations of DOM in leachate solutions had no evident differences between the freeze-thaw and unfrozen treated soil columns, the concentrations of DOM in the leachate solutions B, W and J were different. Freeze-thaw cycles resulted in increased concentrations of Cd in the leachate solutions in the order J > W > B, and promoted a deeper migration of Cd in the soil columns. Thus, it was shown that freeze-thaw cycles may increase the risk of groundwater pollution by Cd.

  11. Nocturnal Vertical Gradients of O3, NO2, NO3, HONO, HCHO, and SO2 in Los Angeles, CA, during CalNex 2010

    NASA Astrophysics Data System (ADS)

    Tsai, J.; Pikelnaya, O.; Hurlock, S. C.; Wong, K.; Cheung, R.; Haman, C. L.; Lefer, B. L.; Stutz, J.

    2010-12-01

    Nocturnal chemistry, through the conversion and removal of air pollutants, plays an important role in determining the initial condition for photochemistry during the following day. In the stable nocturnal boundary layer (NBL) the interplay between suppressed vertical mixing and surface emissions of NOx and VOCs can result in pronounced vertical trace gas profiles. The resulting altitude dependence of nocturnal chemistry makes the interpretation of ground observations challenging. In particular, the quantification of the nocturnal loss of NOx, due to NO3 and N2O5 chemistry, requires observations throughout the entire vertical extent of the NBL. The formation of daytime radical precursors, such as HONO, is also altitude dependent. An accurate assessment of their impact on daytime chemistry requires measurements of their profiles during the night and morning. Here we present observations from the CalNex-LA experiment, which took place from May 15 to June 15, 2010 on the east side of the Los Angeles Basin, CA. A Long-Path Differential Optical Absorption Spectrometer (LP-DOAS) was set up on the roof of the Millikan library (265 m asl, 35m agl) on the campus of the California Institute of Technology. Four retroreflector arrays were mounted about 5 -7 km North-East of the instrument at 310m, 353m, 487m and 788 m asl. The vertical profiles of NO3, HONO, NO2, O3, HCHO, and SO2 were retrieved at altitude intervals of 35-78m, 78-121m, 121-255m and 255-556m above the ground. During many nights vertical gradients were observed, with elevated NO2 and HONO concentrations near the surface and larger ozone and NO3 concentrations aloft. Simultaneous ceilometer observations of the NBL structure show the impact of meteorology on the vertical trace gas distributions. We will discuss the consequences of trace gases gradients on the nocturnal NOx budget.

  12. The role of the geothermal gradient in the emplacement and replenishment of ground ice on Mars

    NASA Technical Reports Server (NTRS)

    Clifford, Stephen M.

    1993-01-01

    Knowledge of the mechanisms by which ground ice is emplaced, removed, and potentially replenished, are critical to understanding the climatic and hydrologic behavior of water on Mars, as well as the morphologic evolution of its surface. Because of the strong temperature dependence of the saturated vapor pressure of H2O, the atmospheric emplacement or replenishment of ground ice is prohibited below the depth at which crustal temperatures begin to monotonically increase due to geothermal heating. In contrast, the emplacement and replenishment of ground ice from reservoirs of H2O residing deep within the crust can occur by at least three different thermally-driven processes, involving all three phases of water. In this regard, Clifford has discussed how the presence of a geothermal gradient as small as 15 K/km can give rise to a corresponding vapor pressure gradient sufficient to drive the vertical transport of 1 km of water from a reservoir of ground water at depth to the base of the cryosphere every 10(exp 6) - 10(exp 7) years. This abstract expands on this earlier treatment by considering the influence of thermal gradients on the transport of H2O at temperatures below the freezing point.

  13. Crosswind Shear Gradient Affect on Wake Vortices

    NASA Technical Reports Server (NTRS)

    Proctor, Fred H.; Ahmad, Nashat N.

    2011-01-01

    Parametric simulations with a Large Eddy Simulation (LES) model are used to explore the influence of crosswind shear on aircraft wake vortices. Previous studies based on field measurements, laboratory experiments, as well as LES, have shown that the vertical gradient of crosswind shear, i.e. the second vertical derivative of the environmental crosswind, can influence wake vortex transport. The presence of nonlinear vertical shear of the crosswind velocity can reduce the descent rate, causing a wake vortex pair to tilt and change in its lateral separation. The LES parametric studies confirm that the vertical gradient of crosswind shear does influence vortex trajectories. The parametric results also show that vortex decay from the effects of shear are complex since the crosswind shear, along with the vertical gradient of crosswind shear, can affect whether the lateral separation between wake vortices is increased or decreased. If the separation is decreased, the vortex linking time is decreased, and a more rapid decay of wake vortex circulation occurs. If the separation is increased, the time to link is increased, and at least one of the vortices of the vortex pair may have a longer life time than in the case without shear. In some cases, the wake vortices may never link.

  14. Freezing induces a loss of freeze tolerance in an overwintering insect.

    PubMed

    Brown, C L; Bale, J S; Walters, K F A

    2004-07-22

    Cold-hardy insects overwinter by one of two main strategies: freeze tolerance and freeze avoidance by supercooling. As a general model, many freeze-tolerant species overwinter in extreme climates, freeze above -10 degrees C via induction by ice-nucleating agents, and once frozen, can survive at temperatures of up to 40 degrees C or more below the initial freezing temperature or supercooling point (SCP). It has been assumed that the SCP of freeze-tolerant insects is unaffected by the freezing process and that the freeze-tolerant state is therefore retained in winter though successive freeze-thaw cycles of the body tissues and fluids. Studies on the freeze-tolerant larva of the hoverfly Syrphus ribesii reveal this assumption to be untrue. When a sample with a mean 'first freeze' SCP of -7.6 degrees C (range of -5 degrees C to -9.5 degrees C) were cooled, either to -10 degrees C or to their individual SCP, on five occasions, the mean SCP was significantly depressed, with some larvae subsequently freezing as low as -28 degrees C. Only larvae that froze at the same consistently high temperature above -10 degrees C were alive after being frozen five times. The wider occurrence of this phenomenon would require a fundamental reassessment of the dynamics and distinctions of the freeze-tolerant and freeze-avoiding strategies of insect overwintering. Copyright 2004 The Royal Society

  15. Method and apparatus for determining vertical heat flux of geothermal field

    DOEpatents

    Poppendiek, Heinz F.

    1982-01-01

    A method and apparatus for determining vertical heat flux of a geothermal field, and mapping the entire field, is based upon an elongated heat-flux transducer (10) comprised of a length of tubing (12) of relatively low thermal conductivity with a thermopile (20) inside for measuring the thermal gradient between the ends of the transducer after it has been positioned in a borehole for a period sufficient for the tube to reach thermal equilibrium. The transducer is thermally coupled to the surrounding earth by a fluid annulus, preferably water or mud. A second transducer comprised of a length of tubing of relatively high thermal conductivity is used for a second thermal gradient measurement. The ratio of the first measurement to the second is then used to determine the earth's thermal conductivity, k.sub..infin., from a precalculated graph, and using the value of thermal conductivity thus determined, then determining the vertical earth temperature gradient, b, from predetermined steady state heat balance equations which relate the undisturbed vertical earth temperature distributions at some distance from the borehole and earth thermal conductivity to the temperature gradients in the transducers and their thermal conductivity. The product of the earth's thermal conductivity, k.sub..infin., and the earth's undisturbed vertical temperature gradient, b, then determines the earth's vertical heat flux. The process can be repeated many times for boreholes of a geothermal field to map vertical heat flux.

  16. Freezing and thawing or freezing, thawing, and aging effects on beef tenderness.

    PubMed

    Grayson, A L; King, D A; Shackelford, S D; Koohmaraie, M; Wheeler, T L

    2014-06-01

    The objective of this study was to determine the effect of freezing and thawing or freezing and thawing with an additional aging period after frozen storage on the tenderness of longissimus lumborum (LL) and semitendinosus (ST) steaks relative to aged, fresh steaks. Left-side LL and ST (n = 35 each) were obtained from U.S. Select carcasses classified at the grading stand by the U.S. Meat Animal Research Center visible and near-infrared spectroscopy tenderness system to have predicted slice shear force greater than 16.5 kg at 14 d postmortem. At 2 d postmortem, 2.54 cm thick steaks were cut from each muscle and assigned to 1 of the following treatments: 2 d fresh (2FRESH), 2 d freeze + thaw (2FREEZE), 2 d freeze + thaw + 12 d age (2FREEZE+12AGE), 14 d fresh (14FRESH), 14 d freeze + thaw (14FREEZE), 14 d freeze + thaw + 14 d age (14FREEZE+14AGE), and 28 d fresh (28FRESH). Steaks assigned to a freezing treatment were frozen at -26°C for 30 d before thawing/cooking or thawing with an additional aging period at 2°C. Slice shear force for LL and ST was lower (P < 0.01) for 2FREEZE (27.4 and 24.5 kg) and 14FREEZE (22.4 and 22.4 kg) compared to 2FRESH (33.0 and 29.2 kg) and 14FRESH (25.3 and 25.5 kg), respectively. Slice shear force for LL and ST was lower (P < 0.01) for 2FREEZE+12AGE (17.8 and 20.8 kg) and 14FREEZE+14AGE (14.6 and 19.0 kg) compared to 14FRESH (25.3 and 25.5 kg) and 28FRESH (18.7 and 21.7 kg), respectively. Desmin degradation for LL was not different (P > 0.05) between 2FREEZE (21.0%) and 2FRESH (14.6%) or between 14FREEZE (40.4%) and 14FRESH (38.4%); however, desmin degradation was higher (P < 0.06) in 2FREEZE+12AGE (46.7%) and 14FREEZE+14AGE (71.1%) when compared to 14FRESH (38.4%) and 28FRESH (60.5%), respectively. Cooking loss for LL was higher (P < 0.01) in 2FREEZE+12AGE (15.2%) compared to 14FRESH (14.0%) but was not different (P > 0.05) between 14FREEZE+14AGE (15.0%) and 28FRESH (14.3%). Freezing and thawing or a combination of freezing, thawing

  17. Florida Harvester Ant Nest Architecture, Nest Relocation and Soil Carbon Dioxide Gradients

    PubMed Central

    Tschinkel, Walter R.

    2013-01-01

    Colonies of the Florida harvester ant, Pogonomyrmex badius, excavate species-typical subterranean nests up the 3 m deep with characteristic vertical distribution of chamber area/shape, spacing between levels and vertical arrangement of the ants by age and brood stage. Colonies excavate and occupy a new nest about once a year, and doing so requires that they have information about the depth below ground. Careful excavation and mapping of vacated and new nests revealed that there was no significant difference between the old and new nests in any measure of nest size, shape or arrangement. Colonies essentially built a replicate of the just-vacated nest (although details differed), and they did so in less than a week. The reason for nest relocation is not apparent. Tschinkel noted that the vertical distribution of chamber area, worker age and brood type was strongly correlated to the soil carbon dioxide gradient, and proposed that this gradient serves as a template for nest excavation and vertical distribution. To test this hypothesis, the carbon dioxide gradient of colonies that were just beginning to excavate a new nest was eliminated by boring 6 vent holes around the forming nest, allowing the soil CO2 to diffuse into the atmosphere and eliminating the gradient. Sadly, neither the nest architecture nor the vertical ant distribution of vented nests differed from either unvented control or from their own vacated nest. In a stronger test, workers excavated a new nest under a reversed carbon dioxide gradient (high concentration near the surface, low below). Even under these conditions, the new and old nests did not differ significantly, showing that the soil carbon dioxide gradient does not serve as a template for nest construction or vertical worker distribution. The possible importance of soil CO2 gradients for soil-dwelling animals is discussed. PMID:23555829

  18. Freezing Bubbles

    NASA Astrophysics Data System (ADS)

    Kingett, Christian; Ahmadi, Farzad; Nath, Saurabh; Boreyko, Jonathan

    2017-11-01

    The two-stage freezing process of a liquid droplet on a substrate is well known; however, how bubbles freeze has not yet been studied. We first deposited bubbles on a silicon substrate that was chilled at temperatures ranging from -10 °C to -40 °C, while the air was at room temperature. We observed that the freeze front moved very slowly up the bubble, and in some cases, even came to a complete halt at a critical height. This slow freezing front propagation can be explained by the low thermal conductivity of the thin soap film, and can be observed more clearly when the bubble size or the surface temperature is increased. This delayed freezing allows the frozen portion of the bubble to cool the air within the bubble while the top part is still liquid, which induces a vapor pressure mismatch that either collapses the top or causes the top to pop. In cases where the freeze front reaches the top of the bubble, a portion of the top may melt and slowly refreeze; this can happen more than just once for a single bubble. We also investigated freezing bubbles inside of a freezer where the air was held at -20 °C. In this case, the bubbles freeze quickly and the ice grows radially from nucleation sites instead of perpendicular to the surface, which provides a clear contrast with the conduction limited room temperature bubbles.

  19. Freeze for action: neurobiological mechanisms in animal and human freezing

    PubMed Central

    2017-01-01

    Upon increasing levels of threat, animals activate qualitatively different defensive modes, including freezing and active fight-or-flight reactions. Whereas freezing is a form of behavioural inhibition accompanied by parasympathetically dominated heart rate deceleration, fight-or-flight reactions are associated with sympathetically driven heart rate acceleration. Despite the potential relevance of freezing for human stress-coping, its phenomenology and neurobiological underpinnings remain largely unexplored in humans. Studies in rodents have shown that freezing depends on amygdala projections to the brainstem (periaqueductal grey). Recent neuroimaging studies in humans have indicated that similar brain regions may be involved in human freezing. In addition, flexibly shifting between freezing and active defensive modes is critical for adequate stress-coping and relies on fronto-amygdala connections. This review paper presents a model detailing these neural mechanisms involved in freezing and the shift to fight-or-flight action. Freezing is not a passive state but rather a parasympathetic brake on the motor system, relevant to perception and action preparation. Study of these defensive responses in humans may advance insights into human stress-related psychopathologies characterized by rigidity in behavioural stress reactions. The paper therefore concludes with a research agenda to stimulate translational animal–human research in this emerging field of human defensive stress responses. This article is part of the themed issue ‘Movement suppression: brain mechanisms for stopping and stillness’. PMID:28242739

  20. Vertical gradients in water chemistry and age in the Northern High Plains Aquifer, Nebraska, 2003

    USGS Publications Warehouse

    McMahon, P.B.; Böhlke, J.K.; Carney, C.P.

    2007-01-01

    The northern High Plains aquifer is the primary source of water used for domestic, industrial, and irrigation purposes in parts of Colorado, Kansas, Nebraska, South Dakota, and Wyoming. Despite the aquifer’s importance to the regional economy, fundamental ground-water characteristics, such as vertical gradients in water chemistry and age, remain poorly defined. As part of the U.S. Geological Survey’s National Water-Quality Assessment Program, water samples from nested, short-screen monitoring wells installed in the northern High Plains aquifer were analyzed for major ions, nutrients, trace elements, dissolved organic carbon, pesticides, stable and radioactive isotopes, dissolved gases, and other parameters to evaluate vertical gradients in water chemistry and age in the aquifer. Chemical data and tritium and radiocarbon ages show that water in the aquifer was chemically and temporally stratified in the study area, with a relatively thin zone of recently recharged water (less than 50 years) near the water table overlying a thicker zone of older water (1,800 to 15,600 radiocarbon years). In areas where irrigated agriculture was an important land use, the recently recharged ground water was characterized by elevated concentrations of major ions and nitrate and the detection of pesticide compounds. Below the zone of agricultural influence, major-ion concentrations exhibited small increases with depth and distance along flow paths because of rock/water interactions. The concentration increases were accounted for primarily by dissolved calcium, sodium, bicarbonate, sulfate, and silica. In general, the chemistry of ground water throughout the aquifer was of high quality. None of the approximately 90 chemical constituents analyzed in each sample exceeded primary drinking-water standards.Mass-balance models indicate that changes in groundwater chemistry along flow paths in the aquifer can be accounted for by small amounts of feldspar and calcite dissolution; goethite

  1. Investigating the Mpemba Effect: When Hot Water Freezes Faster than Cold Water

    ERIC Educational Resources Information Center

    Ibekwe, R. T.; Cullerne, J. P.

    2016-01-01

    Under certain conditions a body of hot liquid may cool faster and freeze before a body of colder liquid, a phenomenon known as the Mpemba Effect. An initial difference in temperature of 3.2 °C enabled warmer water to reach 0 °C in 14% less time than colder water. Convection currents in the liquid generate a temperature gradient that causes more…

  2. Characteristics of sugar surfactants in stabilizing proteins during freeze-thawing and freeze-drying.

    PubMed

    Imamura, Koreyoshi; Murai, Katsuyuki; Korehisa, Tamayo; Shimizu, Noriyuki; Yamahira, Ryo; Matsuura, Tsutashi; Tada, Hiroko; Imanaka, Hiroyuki; Ishida, Naoyuki; Nakanishi, Kazuhiro

    2014-06-01

    Sugar surfactants with different alkyl chain lengths and sugar head groups were compared for their protein-stabilizing effect during freeze-thawing and freeze-drying. Six enzymes, different in terms of tolerance against inactivation because of freeze-thawing and freeze-drying, were used as model proteins. The enzyme activities that remained after freeze-thawing and freeze-drying in the presence of a sugar surfactant were measured for different types and concentrations of sugar surfactants. Sugar surfactants stabilized all of the tested enzymes both during freeze-thawing and freeze-drying, and a one or two order higher amount of added sugar surfactant was required for achieving protein stabilization during freeze-drying than for the cryoprotection. The comprehensive comparison showed that the C10-C12 esters of sucrose or trehalose were the most effective through the freeze-drying process: the remaining enzyme activities after freeze-thawing and freeze-drying increased at the sugar ester concentrations of 1-10 and 10-100 μM, respectively, and increased to a greater extent than for the other surfactants at higher concentrations. Results also indicate that, when a decent amount of sugar was also added, the protein-stabilizing effect of a small amount of sugar ester through the freeze-drying process could be enhanced. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  3. Long-distance abscisic acid signalling under different vertical soil moisture gradients depends on bulk root water potential and average soil water content in the root zone.

    PubMed

    Puértolas, Jaime; Alcobendas, Rosalía; Alarcón, Juan J; Dodd, Ian C

    2013-08-01

    To determine how root-to-shoot abscisic acid (ABA) signalling is regulated by vertical soil moisture gradients, root ABA concentration ([ABA](root)), the fraction of root water uptake from, and root water potential of different parts of the root zone, along with bulk root water potential, were measured to test various predictive models of root xylem ABA concentration [RX-ABA](sap). Beans (Phaseolus vulgaris L. cv. Nassau) were grown in soil columns and received different irrigation treatments (top and basal watering, and withholding water for varying lengths of time) to induce different vertical soil moisture gradients. Root water uptake was measured at four positions within the column by continuously recording volumetric soil water content (θv). Average θv was inversely related to bulk root water potential (Ψ(root)). In turn, Ψ(root) was correlated with both average [ABA](root) and [RX-ABA](sap). Despite large gradients in θv, [ABA](root) and root water potential was homogenous within the root zone. Consequently, unlike some split-root studies, root water uptake fraction from layers with different soil moisture did not influence xylem sap (ABA). This suggests two different patterns of ABA signalling, depending on how soil moisture heterogeneity is distributed within the root zone, which might have implications for implementing water-saving irrigation techniques. © 2013 John Wiley & Sons Ltd.

  4. A practical method to detect the freezing/thawing onsets of seasonal frozen ground in Alaska

    NASA Astrophysics Data System (ADS)

    Chen, Xiyu; Liu, Lin

    2017-04-01

    Microwave remote sensing can provide useful information about freeze/thaw state of soil at the Earth surface. An edge detection method is applied in this study to estimate the onsets of soil freeze/thaw state transition using L band space-borne radiometer data. The Soil Moisture Active Passive (SMAP) mission has a L band radiometer and can provide daily brightness temperature (TB) with horizontal/vertical polarizations. We use the normalized polarization ratios (NPR) calculated based on the Level-1C TB product of SMAP (spatial resolution: 36 km) as the indicator for soil freeze/thaw state, to estimate the freezing and thawing onsets in Alaska in the year of 2015 and 2016. NPR is calculated based on the difference between TB at vertical and horizontal polarizations. Therefore, it is strongly sensitive to liquid water content change in the soil and independent with the soil temperature. Onset estimation is based on the detection of abrupt changes of NPR in transition seasons using edge detection method, and the validation is to compare estimated onsets with the onsets derived from in situ measurement. According to the comparison, the estimated onsets were generally 15 days earlier than the measured onsets in 2015. However, in 2016 there were 4 days in average for the estimation earlier than the measured, which may be due to the less snow cover. Moreover, we extended our estimation to the entire state of Alaska. The estimated freeze/thaw onsets showed a reasonable latitude-dependent distribution although there are still some outliers caused by the noisy variation of NPR. At last, we also try to remove these outliers and improve the performance of the method by smoothing the NPR time series.

  5. Vertical distribution of the soil microbiota along a successional gradient in a glacier forefield.

    PubMed

    Rime, Thomas; Hartmann, Martin; Brunner, Ivano; Widmer, Franco; Zeyer, Josef; Frey, Beat

    2015-03-01

    Spatial patterns of microbial communities have been extensively surveyed in well-developed soils, but few studies investigated the vertical distribution of micro-organisms in newly developed soils after glacier retreat. We used 454-pyrosequencing to assess whether bacterial and fungal community structures differed between stages of soil development (SSD) characterized by an increasing vegetation cover from barren (vegetation cover: 0%/age: 10 years), sparsely vegetated (13%/60 years), transient (60%/80 years) to vegetated (95%/110 years) and depths (surface, 5 and 20 cm) along the Damma glacier forefield (Switzerland). The SSD significantly influenced the bacterial and fungal communities. Based on indicator species analyses, metabolically versatile bacteria (e.g. Geobacter) and psychrophilic yeasts (e.g. Mrakia) characterized the barren soils. Vegetated soils with higher C, N and root biomass consisted of bacteria able to degrade complex organic compounds (e.g. Candidatus Solibacter), lignocellulolytic Ascomycota (e.g. Geoglossum) and ectomycorrhizal Basidiomycota (e.g. Laccaria). Soil depth only influenced bacterial and fungal communities in barren and sparsely vegetated soils. These changes were partly due to more silt and higher soil moisture in the surface. In both soil ages, the surface was characterized by OTUs affiliated to Phormidium and Sphingobacteriales. In lower depths, however, bacterial and fungal communities differed between SSD. Lower depths of sparsely vegetated soils consisted of OTUs affiliated to Acidobacteria and Geoglossum, whereas depths of barren soils were characterized by OTUs related to Gemmatimonadetes. Overall, plant establishment drives the soil microbiota along the successional gradient but does not influence the vertical distribution of microbiota in recently deglaciated soils. © 2014 John Wiley & Sons Ltd.

  6. Measurement of the vertical gradient of the semidiurnal tidal wind phase in winter at the 95 km level

    NASA Astrophysics Data System (ADS)

    Schminder, R.; Kurschner, D.

    1984-05-01

    When supplemented by absolute reflection height measurements, low frequency wind measurements in the 90-100 km height range become truly competitive in comparison with the more widely used radar meteor wind observations. For example, height profiles of the wind parameters in the so-called meteor zone can be obtained due to the considerable interdiurnal variability of the average nighttime reflection heights controlled by geomagnetic activity. The phase of the semidiurnal tidal wind is particularly height-dependent. The measured vertical gradient of 1/4 h/km in winter corresponds to a vertical wavelength of about 50 km. Wind measurements in the upper atmosphere, at heights between 90 and 100 km, were carried out at the Collm Geophysical Observatory of Karl Marx University Leipzig for a number of years. These measurements use the closely-spaced receiver method and three measuring paths, on 179, 227, and 272 kHz. They take place every day between sunset and sunrise, i.e., nightly. A night in this sense may last as long as 18 hours in winter. Both the measurements and their evaluation are completely automatic, and the prevailing winds and tides are separated.

  7. Measurement of the Vertical Gradient of the Semidiurnal Tidal Wind Phase in Winter at the 95 Km Level

    NASA Technical Reports Server (NTRS)

    Schminder, R.; Kurschner, D.

    1984-01-01

    When supplemented by absolute reflection height measurements, low frequency wind measurements in the 90-100 km height range become truly competitive in comparison with the more widely used radar meteor wind observations. For example, height profiles of the wind parameters in the so-called meteor zone can be obtained due to the considerable interdiurnal variability of the average nighttime reflection heights controlled by geomagnetic activity. The phase of the semidiurnal tidal wind is particularly height-dependent. The measured vertical gradient of 1/4 h/km in winter corresponds to a vertical wavelength of about 50 km. Wind measurements in the upper atmosphere, at heights between 90 and 100 km, were carried out at the Collm Geophysical Observatory of Karl Marx University Leipzig for a number of years. These measurements use the closely-spaced receiver method and three measuring paths, on 179, 227, and 272 kHz. They take place every day between sunset and sunrise, i.e., nightly. A night in this sense may last as long as 18 hours in winter. Both the measurements and their evaluation are completely automatic, and the prevailing winds and tides are separated.

  8. A comparison of freezing-damage during isochoric and isobaric freezing of the potato.

    PubMed

    Lyu, Chenang; Nastase, Gabriel; Ukpai, Gideon; Serban, Alexandru; Rubinsky, Boris

    2017-01-01

    Freezing is commonly used for food preservation. It is usually done under constant atmospheric pressure (isobaric). While extending the life of the produce, isobaric freezing has detrimental effects. It causes loss of food weight and changes in food quality. Using thermodynamic analysis, we have developed a theoretical model of the process of freezing in a constant volume system (isochoric). The mathematical model suggests that the detrimental effects associated with isobaric freezing may be reduced in an isochoric freezing system. To explore this hypothesis, we performed a preliminary study on the isochoric freezing of a produce with which our group has experience, the potato. Experiments were performed in an isochoric freezing device we designed. The device is robust and has no moving parts. For comparison, we used a geometrically identical isobaric freezing device. Following freezing and thawing, the samples were weighed, examined with colorimetry, and examined with microscopy. It was found that potatoes frozen to -5 °C in an isochoric system experienced no weight loss and limited enzymatic browning. In contrast the -5 °C isobaric frozen potato experienced substantial weight loss and substantial enzymatic browning. Microscopic analysis shows that the structural integrity of the potato is maintained after freezing in the isochoric system and impaired after freezing in the isobaric system. Tissue damage during isobaric freezing is caused by the increase in extracellular osmolality and the mechanical damage by ice crystals. Our thermodynamic analysis predicts that during isochoric freezing the intracellular osmolality remains comparable to the extracellular osmolality and that isochoric systems can be designed to eliminate the mechanical damage by ice. The results of this preliminary study seem to confirm the theoretical predictions. This is a preliminary exploratory study on isochoric freezing of food. We have shown that the quality of a food product preserved

  9. A comparison of freezing-damage during isochoric and isobaric freezing of the potato

    PubMed Central

    Serban, Alexandru; Rubinsky, Boris

    2017-01-01

    Background Freezing is commonly used for food preservation. It is usually done under constant atmospheric pressure (isobaric). While extending the life of the produce, isobaric freezing has detrimental effects. It causes loss of food weight and changes in food quality. Using thermodynamic analysis, we have developed a theoretical model of the process of freezing in a constant volume system (isochoric). The mathematical model suggests that the detrimental effects associated with isobaric freezing may be reduced in an isochoric freezing system. To explore this hypothesis, we performed a preliminary study on the isochoric freezing of a produce with which our group has experience, the potato. Method Experiments were performed in an isochoric freezing device we designed. The device is robust and has no moving parts. For comparison, we used a geometrically identical isobaric freezing device. Following freezing and thawing, the samples were weighed, examined with colorimetry, and examined with microscopy. Results It was found that potatoes frozen to −5 °C in an isochoric system experienced no weight loss and limited enzymatic browning. In contrast the −5 °C isobaric frozen potato experienced substantial weight loss and substantial enzymatic browning. Microscopic analysis shows that the structural integrity of the potato is maintained after freezing in the isochoric system and impaired after freezing in the isobaric system. Discussion Tissue damage during isobaric freezing is caused by the increase in extracellular osmolality and the mechanical damage by ice crystals. Our thermodynamic analysis predicts that during isochoric freezing the intracellular osmolality remains comparable to the extracellular osmolality and that isochoric systems can be designed to eliminate the mechanical damage by ice. The results of this preliminary study seem to confirm the theoretical predictions. Conclusion This is a preliminary exploratory study on isochoric freezing of food. We have

  10. To freeze or not to freeze embryos: clarity, confusion and conflict.

    PubMed

    Goswami, Mohar; Murdoch, Alison P; Haimes, Erica

    2015-06-01

    Although embryo freezing is a routine clinical practice, there is little contemporary evidence on how couples make the decision to freeze their surplus embryos, or of their perceptions during that time. This article describes a qualitative study of 16 couples who have had in vitro fertilisation (IVF) treatment. The study question was 'What are the personal and social factors that patients consider when deciding whether to freeze embryos?' We show that while the desire for a baby is the dominant drive, couples' views revealed more nuanced and complex considerations in the decision-making process. It was clear that the desire to have a baby influenced couples' decision-making and that they saw freezing as 'part of the process'. However, there were confusions associated with the term 'freezing' related to concerns about the safety of the procedure. Despite being given written information, couples were confused about the practical aspects of embryo freezing, which suggests they were preoccupied with the immediate demands of IVF. Couples expressed ethical conflicts about freezing 'babies'. We hope the findings from this study will inform clinicians and assist them in providing support to couples confronted with this difficult decision-making.

  11. Effect of Freeze-Thaw Cycles on Soil Nitrogen Reactive Transport in a Polygonal Arctic Tundra Ecosystem at Barrow AK Using 3-D Coupled ALM-PFLOTRAN

    NASA Astrophysics Data System (ADS)

    Yuan, F.; Wang, G.; Painter, S. L.; Tang, G.; Xu, X.; Kumar, J.; Bisht, G.; Hammond, G. E.; Mills, R. T.; Thornton, P. E.; Wullschleger, S. D.

    2017-12-01

    In Arctic tundra ecosystem soil freezing-thawing is one of dominant physical processes through which biogeochemical (e.g., carbon and nitrogen) cycles are tightly coupled. Besides hydraulic transport, freezing-thawing can cause pore water movement and aqueous species gradients, which are additional mechanisms for soil nitrogen (N) reactive-transport in Tundra ecosystem. In this study, we have fully coupled an in-development ESM(i.e., Advanced Climate Model for Energy, ACME)'s Land Model (ALM) aboveground processes with a state-of-the-art massively parallel 3-D subsurface thermal-hydrology and reactive transport code, PFLOTRAN. The resulting coupled ALM-PFLOTRAN model is a Land Surface Model (LSM) capable of resolving 3-D soil thermal-hydrological-biogeochemical cycles. This specific version of PFLOTRAN has incorporated CLM-CN Converging Trophic Cascade (CTC) model and a full and simple but robust soil N cycle. It includes absorption-desorption for soil NH4+ and gas dissolving-degasing process as well. It also implements thermal-hydrology mode codes with three newly-modified freezing-thawing algorithms which can greatly improve computing performance in regarding to numerical stiffness at freezing-point. Here we tested the model in fully 3-D coupled mode at the Next Generation Ecosystem Experiment-Arctic (NGEE-Arctic) field intensive study site at the Barrow Environmental Observatory (BEO), AK. The simulations show that: (1) synchronous coupling of soil thermal-hydrology and biogeochemistry in 3-D can greatly impact ecosystem dynamics across polygonal tundra landscape; and (2) freezing-thawing cycles can add more complexity to the system, resulting in greater mobility of soil N vertically and laterally, depending upon local micro-topography. As a preliminary experiment, the model is also implemented for Pan-Arctic region in 1-D column mode (i.e. no lateral connection), showing significant differences compared to stand-alone ALM. The developed ALM-PFLOTRAN coupling

  12. The vertical profile of radar reflectivity of convective cells: A strong indicator of storm intensity and lightning probability?

    NASA Technical Reports Server (NTRS)

    Zipser, Edward J.; Lutz, Kurt R.

    1994-01-01

    Reflectivity data from Doppler radars are used to construct vertical profiles of radar reflectivity (VPRR) of convective cells in mesoscale convective systems (MCSs) in three different environmental regimes. The National Center for Atmospheric Research CP-3 and CP-4 radars are used to calculate median VPRR for MCSs in the Oklahoma-Kansas Preliminary Regional Experiment for STORM-Central in 1985. The National Oceanic and Atmospheric Administration-Tropical Ocean Global Atmosphere radar in Darwin, Australia, is used to calculate VPRR for MCSs observed both in oceanic, monsoon regimes and in continental, break period regimes during the wet seasons of 1987/88 and 1988/89. The midlatitude and tropical continental VPRRs both exhibit maximum reflectivity somewhat above the surface and have a gradual decrease in reflectivity with height above the freezing level. In sharp contrast, the tropical oceanic profile has a maximum reflectivity at the lowest level and a very rapid decrease in reflectivity with height beginning just above the freezing level. The tropical oceanic profile in the Darwin area is almost the same shape as that for two other tropical oceanic regimes, leading to the conclustion that it is characteristic. The absolute values of reflectivity in the 0 to 20 C range are compared with values in the literature thought to represent a threshold for rapid storm electrification leading to lightning, about 40 dBZ at -10 C. The large negative vertical gradient of reflectivity in this temperature range for oceanic storms is hypothesized to be a direct result of the characteristically weaker vertical velocities observed in MCSs over tropical oceans. It is proposed, as a necessary condition for rapid electrification, that a convective cell must have its updraft speed exceed some threshold value. Based upon field program data, a tentative estimate for the magnitude of this threshold is 6-7 m/s for mean speed and 10-12 m/s for peak speed.

  13. Density gradient centrifugation prior to cryopreservation and hypotaurine supplementation improve post-thaw quality of sperm from infertile men with oligoasthenoteratozoospermia.

    PubMed

    Brugnon, F; Ouchchane, L; Pons-Rejraji, H; Artonne, C; Farigoule, M; Janny, L

    2013-08-01

    Can selection of spermatozoa by density gradient centrifugation prior to cryopreservation and/or hypotaurine supplementation improve the post-thaw quality of sperm from infertile men with oligoasthenoteratozoospermia? Sperm selection by density gradient centrifugation before freezing and supplementation of the media by hypotaurine is beneficial for the cryopreservation of semen samples of patients with oligoasthenoteratozoospermia. Sperm from men with oligoasthenoteratozoospermia are more susceptible than normal to cryoinjury. Density gradient centrifugation before sperm freezing may allow the selection of a subpopulation of spermatozoa more resistant to cryopreservation. Hypotaurine is an antioxidant with a protective effect on sperm functions. The experiment was carried out according to a factorial design involving two binary factors resulting in four treatment combinations which were randomly allocated in oligoasthenoteratozoospermia sperm samples from 64 patients recruited between January 2009 and June 2010. Semen was provided by 64 men undergoing evaluation for infertility at the Centre for Reproductive Medicine of the University Hospital in Clermont-Ferrand, France, between January 2009 and June 2010. Four treatment combinations were tested: sperm freezing before selection without (F-S/H-; n = 16) and with hypotaurine supplementation (F-S/H+; n = 16); sperm selection before freezing without (S-F/H-; n = 16) and with hypotaurine supplementation (S-F/H+; n = 16). Measurements of sperm recovery rates and markers of apoptosis (externalization of phosphatidylserine (PS), mitochondrial membrane potential and DNA fragmentation) were compared in recovered spermatozoa after each procedure. Higher recovery rates of progressive and total motile spermatozoa were observed when sperm selection was performed before freezing (P < 0.05). The protective effect of hypotaurine was only observed on the percentage of live spermatozoa with PS externalization among total live

  14. Spatial and vertical gradients in the stable carbon isotope composition of Lower Circumpolar Deep Water over the last 900 thousand years

    NASA Astrophysics Data System (ADS)

    Williams, T.; Hillenbrand, C. D.; Piotrowski, A. M.; Smith, J.; Hodell, D. A.; Frederichs, T.; Allen, C. S.

    2014-12-01

    Changes in stable carbon isotopes (δ13C) recorded in benthic foraminiferal calcite reflect that of the dissolved inorganic carbon (DIC) of ambient seawater, and thus are used to reconstruct past changes in water mass mixing. Records of benthic foraminiferal δ13C from the Atlantic Ocean have revealed the development of a sharp vertical δ13C gradient between 2300-2500m water depth during successive glacial periods throughout the Late Quaternary, with extremely negative δ13C values recorded below this depth. It had been hypothesised that this gradient resulted from an increased stratification of water masses within the glacial Atlantic Ocean, and that these extreme δ13C values originated in the Southern Ocean. However the mechanisms behind the formation of this gradient and extreme δ13C depletion have remained unclear. This is in part due to the poor preservation of calcareous microfossils in the corrosive waters below 2500-3000m found in the Southern Ocean, which hampers our understanding of this key region. Here we present a unique new δ13C deep water record measured on benthic foraminifera (Cibicidoides spp.) from a sediment core recovered from 2100m water depth in the Amundsen Sea, south-eastern Pacific sector of the Southern Ocean. The site is bathed in Lower Circumpolar Deep Water (LCDW) today, and combined palaeomagnetic and oxygen isotope stratigraphy show that the sediments continuously span at least the last 890 ka. A comparison of this new δ13C data with other LCDW records from ODP Sites 1089/1090 in the South Atlantic and ODP Site 1123 in the Southwest Pacific demonstrate a clear spatial gradient in circum-Antarctic LCDW during glacial periods. The pool of extremely depleted glacial deep marine δ13C is restricted to the Atlantic Sector of the Southern Ocean, with increasingly positive δ13C values found in the Southwest Pacific and the south-eastern Pacific sector of the Southern Ocean. This implies that the δ13C depletion in the deep glacial

  15. Evaluation of anti-freeze viscosity modifier for potential external tank applications

    NASA Technical Reports Server (NTRS)

    Lynn, R. O. L.

    1981-01-01

    Viscosity modifiers and gelling agents were evaluated in combination with ethylene glycol and dimethyl sulfoxide water eutectics. Pectin and agarose are found to gel these eutectics effectively in low concentration, but the anti-freeze protection afforded by these compositions is found to be marginal in simulations of the intended applications. Oxygen vent shutters and vertical metallic surfaces were simulated, with water supplied as a spray, dropwise, and by condensation from the air.

  16. Studies on interface curvature during vertical Bridgman growth of InP in a flat-bottom container

    NASA Astrophysics Data System (ADS)

    Rudolph, P.; Matsumoto, F.; Fukuda, T.

    1996-01-01

    A simplified numerical simulation of the dynamic behaviour of the solid-liquid interface curvature during modified vertical Bridgman growth of 2 inch InP single crystals, in a flat-bottom container, with a seed of the same diameter is presented. The results agree with striation patterns observed by transmission X-ray topography. A nearly flat interface with slightly constant concavity has been ascertained in the front half of the grown ingots. It can be assumed that such a steady interface morphology is one of the basic requirements for the observed twin-free and reduced dislocation growth in this region. In an attempt to optimize the shape of the melting point isotherm in the last-to-freeze part of the crystals, the axial temperature gradient, the seed length, the growth velocity, the melt temperature and the conditions of heat transfer (different ambient atmospheres and plugs) as well as the temperature profile in the top region above the encapsulant have been varied in the model.

  17. Vertical groundwater flow in Permo-Triassic sediments underlying two cities in the Trent River Basin (UK)

    NASA Astrophysics Data System (ADS)

    Taylor, R. G.; Cronin, A. A.; Trowsdale, S. A.; Baines, O. P.; Barrett, M. H.; Lerner, D. N.

    2003-12-01

    The vertical component of groundwater flow that is responsible for advective penetration of contaminants in sandstone aquifers is poorly understood. This lack of knowledge is of particular concern in urban areas where abstraction disrupts natural groundwater flow regimes and there exists an increased density of contaminant sources. Vertical hydraulic gradients that control vertical groundwater flow were investigated using bundled multilevel piezometers and a double-packer assembly in dedicated boreholes constructed to depths of between 50 and 92 m below ground level in Permo-Triassic sediments underlying two cities within the Trent River Basin of central England (Birmingham, Nottingham). The hydrostratigraphy of the Permo-Triassic sediments, indicated by geophysical logging and hydraulic (packer) testing, demonstrates considerable control over observed vertical hydraulic gradients and, hence, vertical groundwater flow. The direction and magnitude of vertical hydraulic gradients recorded in multilevel piezometers and packers are broadly complementary and range, within error, from +0.1 to -0.7. Groundwater is generally found to flow vertically toward transmissive zones within the hydrostratigraphical profile though urban abstraction from the Sherwood Sandstone aquifer also influences observed vertical hydraulic gradients. Bulk, downward Darcy velocities at two locations affected by abstraction are estimated to be in the order of several metres per year. Consistency in the distribution of hydraulic head with depth in Permo-Triassic sediments is observed over a one-year period and adds support the deduction of hydrostratigraphic control over vertical groundwater flow.

  18. Freezing during tapping tasks in patients with advanced Parkinson's disease and freezing of gait.

    PubMed

    Delval, Arnaud; Defebvre, Luc; Tard, Céline

    2017-01-01

    Parkinson's disease patients with freezing of gait also experience sudden motor blocks (freezing) during other repetitive motor tasks. We assessed the proportion of patients with advanced PD and freezing of gait who also displayed segmental "freezing" in tapping tasks. Fifteen Parkinson's disease patients with freezing of gait were assessed. Freezing of gait was evaluated using a standardized gait trajectory with the usual triggers. Patients performed repetitive tapping movements (as described in the MDS-UPDRS task) with the hands or the feet in the presence or absence of a metronome set to 4 Hz. Movements were recorded with a video motion system. The primary endpoint was the occurrence of segmental freezing in these tapping tasks. The secondary endpoints were (i) the relationship between segmental episodic phenomena and FoG severity, and (ii) the reliability of the measurements. For the upper limbs, freezing was observed more frequently with a metronome (21% of trials) than without a metronome (5%). For the lower limbs, the incidence of freezing was higher than for the upper limbs, and was again observed more frequently in the presence of an auditory cue (47%) than in its absence (14%). Although freezing of the lower limbs was easily assessed during an MDS-UPDRS task with a metronome, it was not correlated with the severity of freezing of gait (as evaluated during a standardized gait trajectory). Only this latter was a reliable measurement in patients with advanced Parkinson's disease.

  19. Heterogeneous freezing of droplets with immersed surface modified mineral dust particles

    NASA Astrophysics Data System (ADS)

    Hartmann, Susan

    2010-05-01

    In the framework of the international measurement campaign FROST II (FReezing Of duST), the heterogeneous freezing of droplets with an immersed surface modified size-segregated mineral dust particles was investigated at LACIS (Leipzig Aerosol Cloud Interaction Simulator, Stratmann et al. 2004). The following measurements were done: LACIS, CFDC (Continuous Flow thermal gradient Diffusion Chamber, Rogers (1988)) and FINCH (Fast Ice Nucleus Chamber Counter, Bundke et al (2008)) were used to analyze the immersion freezing behavior of the treated Arizona Test Dust (ATD) particles at different temperature regimes. The ability to act as IN (Ice Nucleus) in the deposition nucleation mode was quantified by the PINC (Portable Ice Nucleation Chamber) and the CFDC instrument. AMS (Aerosol Mass Spectrometers, e.g. Schneider et al. (2005)) and ATOFMS (Aerosol Time-Of-Flight Mass Spectrometer) measurements were applied to determine particle composition. The hygroscopic growth and the critical super-saturations needed for droplet activation were determined by means of an H-TDMA (Humidity-Tandem Differential Mobility Analyzer) and CCN counter (Cloud Condensation Nucleus counter, Droplet Measurement Technologies, Roberts and Nenes (2005)). The 300 nm ATD particles were chemically and physically treated by coating with sulphuric acid (H2SO4, three different coating thicknesses) and ammonium sulphate ((NH4)2SO4) or by thermal treatment with a thermodenuder operating at 250°C. The H2SO4 coating modified the particles by reacting with particle material, forming soluble sulfates and therefore changing surface properties. AMS showed free H2SO4 only for thick H2SO4 coatings. In the heated section of the thermodenuder coating materials were evaporated partly and the surface properties of the particles were additionally altered. Uncoated particles and those coated with thin coatings of H2SO4, showed almost no hygroscopic growth. Particles coated with thicker coatings of H2SO4 and of (NH4

  20. The 630 nm MIG and the vertical neutral wind in the low latitude nighttime thermosphere

    NASA Technical Reports Server (NTRS)

    Herrero, F. A.; Meriwether, J. W., Jr.

    1994-01-01

    It is shown that large negative divergences (gradients) in the horizontal neutral wind in the equatorial thermosphere can support downward neutral winds in excess of 20 m/s. With attention to the meridional and vertical winds only, the pressure tendency equation is used to derive the expression U(sub z0) approximately equals (Partial derivative U(sub y)/Partial derivative y)H for the vertical wind U(sub z0) at the reference altitude for the pressure tendency equation; H is the atmospheric density scale height, and (Partial derivative U(sub y)/Partial derivative y) is the meridional wind gradient. The velocity gradient associated with the Meridional Intensity Gradient (MIG) of the O((sup 1)D) emission (630 nm) at low latitudes is used to estimate the vertical neutral wind in the MIG region. Velocity gradients derived from MIG data are about 0.5 (m/s)/km) or more, indicating that the MIG region may contain downward neutral winds in excess of 20 m/s. Though direct measurements of the vertical wind are scarce, Fabry-Perot interferometer data of the equatorial F-region above Natal, Brazil, showed downward winds of 30 m/s occurring during a strong meridional wind convergence in 1982. In-situ measurements with the WATS instrument on the DE-2 satellite also show large vertical neutral winds in the equatorial region.

  1. Using Power Ultrasound to Accelerate Food Freezing Processes: Effects on Freezing Efficiency and Food Microstructure.

    PubMed

    Zhang, Peizhi; Zhu, Zhiwei; Sun, Da-Wen

    2018-05-31

    Freezing is an effective way of food preservation. However, traditional freezing methods have the disadvantages of low freezing efficiency and generation of large ice crystals, leading to possible damage of food quality. Power ultrasound assisted freezing as a novel technique can effectively reduce the adverse effects during freezing process. This paper gives an overview on recent researches of power ultrasound technique to accelerate the food freezing processes and illustrates the main principles of power ultrasound assisted freezing. The effects of power ultrasound on liquid food, model solid food as well as fruit and vegetables are discussed, respectively, from the aspects of increasing freezing rate and improving microstructure. It is shown that ultrasound assisted freezing can effectively improve the freezing efficiency and promote the formation of small and evenly distributed ice crystals, resulting in better food quality. Different inherent properties of food samples affect the effectiveness of ultrasound application and optimum ultrasound parameters depend on the nature of the samples. The application of ultrasound to the food industry is more likely on certain types of food products and more efforts are still needed to realize the industrial translation of laboratory results.

  2. Large vertical δ13CDIC gradients in Early Triassic seas of the South China craton: Implications for oceanographic changes related to Siberian Traps volcanism

    NASA Astrophysics Data System (ADS)

    Song, Huyue; Tong, Jinnan; Algeo, Thomas J.; Horacek, Micha; Qiu, Haiou; Song, Haijun; Tian, Li; Chen, Zhong-Qiang

    2013-06-01

    Vertical gradients in the δ13C of seawater dissolved inorganic carbon (Δδ13CDIC) can be estimated for paleomarine systems based on δ13Ccarb data from sections representing a range of depositional water depths. An analysis of eight Lower Triassic sections from the northern Yangtze Platform and Nanpanjiang Basin, representing water depths of ~ 50 to 500 m, allowed reconstruction of Δδ13CDIC in Early Triassic seas of the South China craton for seven time slices representing four negative (N) and three positive (P) carbon-isotope excursions: 8.5‰ (N1), 5.8‰ (P1), 3.5‰ (N2), 6.5‰ (P2), 7.8‰ (N3), - 1.9‰ (P3), and 2.2‰ (N4). These values are much larger than vertical δ13CDIC gradients in the modern ocean (~ 1-3‰) due to intensified stratification and reduced vertical mixing in Early Triassic seas. Peaks in Δδ13CDIC around the PTB (N1) and in the early to mid-Smithian (P2-N3) coincided with episodes of strong climatic warming, reduced marine productivity, and expanded ocean anoxia. The Dienerian-Smithian boundary marks the onset of a major mid-Early Triassic disturbance, commencing ~ 1 Myr after the latest Permian mass extinction, that we link to a second eruptive stage of the Siberian Traps. Inhospitable oceanic conditions generally persisted until the early Spathian, when strong climatic cooling caused re-invigoration of global-ocean circulation, leading to an interval of negative Δδ13CDIC values and a sharp increase in δ13Ccarb driven by upwelling of nutrient-rich deepwaters. These developments marked the end of the main eruptive stage of the Siberian Traps.

  3. Solvent effects in time-dependent self-consistent field methods. II. Variational formulations and analytical gradients

    DOE PAGES

    Bjorgaard, J. A.; Velizhanin, K. A.; Tretiak, S.

    2015-08-06

    This study describes variational energy expressions and analytical excited state energy gradients for time-dependent self-consistent field methods with polarizable solvent effects. Linear response, vertical excitation, and state-specific solventmodels are examined. Enforcing a variational ground stateenergy expression in the state-specific model is found to reduce it to the vertical excitation model. Variational excited state energy expressions are then provided for the linear response and vertical excitation models and analytical gradients are formulated. Using semiempiricalmodel chemistry, the variational expressions are verified by numerical and analytical differentiation with respect to a static external electric field. Lastly, analytical gradients are further tested by performingmore » microcanonical excited state molecular dynamics with p-nitroaniline.« less

  4. Surface freezing of water.

    PubMed

    Pérez-Díaz, J L; Álvarez-Valenzuela, M A; Rodríguez-Celis, F

    2016-01-01

    Freezing, melting, evaporation and condensation of water are essential ingredients for climate and eventually life on Earth. In the present work, we show how surface freezing of supercooled water in an open container is conditioned and triggered-exclusively-by humidity in air. Additionally, a change of phase is demonstrated to be triggered on the water surface forming surface ice crystals prior to freezing of bulk. The symmetry of the surface crystal, as well as the freezing point, depend on humidity, presenting at least three different types of surface crystals. Humidity triggers surface freezing as soon as it overpasses a defined value for a given temperature, generating a plurality of nucleation nodes. An evidence of simultaneous nucleation of surface ice crystals is also provided.

  5. Role of glucose-6-phosphate dehydrogenase in freezing-induced freezing resistance of Populus suaveolens.

    PubMed

    Lin, Shan-Zhi; Zhang, Zhi-Yi; Liu, Wen-Feng; Lin, Yuan-Zhen; Zhang, Qian; Zhu, Bao-Qing

    2005-02-01

    To explore the role of glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) in the enhancement of freezing resistance induced by freezing acclimation, G6PDH was purified from the leaves of 8-week-old Populus suaveolens cuttings. The G6PDH activity in the absence or the presence of reduced dithiothreitol (DTT(red)) were determined, and the changes in superoxide dismutase (SOD), peroxides (POD) and cytosolic G6PDH activities, malondial-dehyde (MDA) content as well as freezing resistance (expressed as LT(50)) of P. suaveolens cuttings during freezing acclimation at -20 degrees C were investigated. The results showed that the purified G6PDH was probably located in the cytosol of P. suaveolens. Freezing acclimation increased the activities of SOD, POD and cytosolic G6PDH, and decreased the MDA content and LT(50) of cuttings, while 2 d of de-acclimation at 25 degrees C resulted in a decrease in SOD, POD and cytosolic G6PDH activities, and caused an increase in MDA content and LT(50). The change in cytosolic G6PDH activity was found to be closely correlated to the levels of SOD, POD and MDA, and to the degree of freezing resistance of cuttings during freezing acclimation. It is suggested that the enhancement of freezing resistance of cuttings induced by freezing acclimation is related to the distinct increase in cytosolic G6PDH activity, which may be involved in the activation of SOD and POD, and the induction of freezing resistance of cuttings.

  6. Assimilation of temperature and hydraulic gradients for quantifying the spatial variability of streambed hydraulics

    NASA Astrophysics Data System (ADS)

    Huang, Xiang; Andrews, Charles B.; Liu, Jie; Yao, Yingying; Liu, Chuankun; Tyler, Scott W.; Selker, John S.; Zheng, Chunmiao

    2016-08-01

    Understanding the spatial and temporal characteristics of water flux into or out of shallow aquifers is imperative for water resources management and eco-environmental conservation. In this study, the spatial variability in the vertical specific fluxes and hydraulic conductivities in a streambed were evaluated by integrating distributed temperature sensing (DTS) data and vertical hydraulic gradients into an ensemble Kalman filter (EnKF) and smoother (EnKS) and an empirical thermal-mixing model. The formulation of the EnKF/EnKS assimilation scheme is based on a discretized 1D advection-conduction equation of heat transfer in the streambed. We first systematically tested a synthetic case and performed quantitative and statistical analyses to evaluate the performance of the assimilation schemes. Then a real-world case was evaluated to calculate assimilated specific flux. An initial estimate of the spatial distributions of the vertical hydraulic gradients was obtained from an empirical thermal-mixing model under steady-state conditions using a constant vertical hydraulic conductivity. Then, this initial estimate was updated by repeatedly dividing the assimilated specific flux by estimates of the vertical hydraulic gradients to obtain a refined spatial distribution of vertical hydraulic gradients and vertical hydraulic conductivities. Our results indicate that optimal parameters can be derived with fewer iterations but greater simulation effort using the EnKS compared with the EnKF. For the field application in a stream segment of the Heihe River Basin in northwest China, the average vertical hydraulic conductivities in the streambed varied over three orders of magnitude (5 × 10-1 to 5 × 102 m/d). The specific fluxes ranged from near zero (qz < ±0.05 m/d) to ±1.0 m/d, while the vertical hydraulic gradients were within the range of -0.2 to 0.15 m/m. The highest and most variable fluxes occurred adjacent to a debris-dam and bridge pier. This phenomenon is very likely

  7. Fundamentals of freeze-drying.

    PubMed

    Nail, Steven L; Jiang, Shan; Chongprasert, Suchart; Knopp, Shawn A

    2002-01-01

    Given the increasing importance of reducing development time for new pharmaceutical products, formulation and process development scientists must continually look for ways to "work smarter, not harder." Within the product development arena, this means reducing the amount of trial and error empiricism in arriving at a formulation and identification of processing conditions which will result in a quality final dosage form. Characterization of the freezing behavior of the intended formulation is necessary for developing processing conditions which will result in the shortest drying time while maintaining all critical quality attributes of the freeze-dried product. Analysis of frozen systems was discussed in detail, particularly with respect to the glass transition as the physical event underlying collapse during freeze-drying, eutectic mixture formation, and crystallization events upon warming of frozen systems. Experiments to determine how freezing and freeze-drying behavior is affected by changes in the composition of the formulation are often useful in establishing the "robustness" of a formulation. It is not uncommon for seemingly subtle changes in composition of the formulation, such as a change in formulation pH, buffer salt, drug concentration, or an additional excipient, to result in striking differences in freezing and freeze-drying behavior. With regard to selecting a formulation, it is wise to keep the formulation as simple as possible. If a buffer is needed, a minimum concentration should be used. The same principle applies to added salts: If used at all, the concentration should be kept to a minimum. For many proteins a combination of an amorphous excipient, such as a disaccharide, and a crystallizing excipient, such as glycine, will result in a suitable combination of chemical stability and physical stability of the freeze-dried solid. Concepts of heat and mass transfer are valuable in rational design of processing conditions. Heat transfer by conduction

  8. Evaluation of spin freezing versus conventional freezing as part of a continuous pharmaceutical freeze-drying concept for unit doses.

    PubMed

    De Meyer, L; Van Bockstal, P-J; Corver, J; Vervaet, C; Remon, J P; De Beer, T

    2015-12-30

    Spin-freezing as alternative freezing approach was evaluated as part of an innovative continuous pharmaceutical freeze-drying concept for unit doses. The aim of this paper was to compare the sublimation rate of spin-frozen vials versus traditionally frozen vials in a batch freeze-dryer, and its impact on total drying time. Five different formulations, each having a different dry cake resistance, were tested. After freezing, the traditionally frozen vials were placed on the shelves while the spin-frozen vials were placed in aluminum vial holders providing radial energy supply during drying. Different primary drying conditions and chamber pressures were evaluated. After 2h of primary drying, the amount of sublimed ice was determined in each vial. Each formulation was monitored in-line using NIR spectroscopy during drying to determine the sublimation endpoint and the influence of drying conditions upon total drying time. For all tested formulations and applied freeze-drying conditions, there was a significant higher sublimation rate in the spin-frozen vials. This can be explained by the larger product surface and the lower importance of product resistance because of the much thinner product layers in the spin frozen vials. The in-line NIR measurements allowed evaluating the influence of applied drying conditions on the drying trajectories. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. A study of the impact of freezing on the lyophilization of a concentrated formulation with a high fill depth.

    PubMed

    Liu, Jinsong; Viverette, Todd; Virgin, Marlin; Anderson, Mitch; Paresh, Dalal

    2005-01-01

    The objective of this study was to evaluate the impact of freezing on the lyophilization of a concentrated formulation with a high fill depth. A model system consisting of a 15-mL fill of 15% (w/w) sulfobutylether 7-beta-cyclodextrin (SBECD) solution in a 30-mL vial was selected for this study. Various freezing methods including single-step freezing, two-step freezing with a super-cooling holding, annealing, vacuum-induced freezing, changing ice habit using tert-butyl-alcohol (TBA), ice nucleation with silver iodide (AgI), as well as combinations of some of the methods, were used in the lyophilization of this model system. This work demonstrated that the freezing process had a significant impact on primary drying rate and product quality of a concentrated formulation with a high fill depth. Annealing, vacuum-induced freezing, and addition of either TBA or an ice nucleating agent (AgI) to the formulation accelerated the subsequent ice sublimation process. Two-step freezing or addition of TBA improved the product quality by eliminating vertical heterogeneity within the cake. The combination of two-step freezing in conjunction with an annealing step was shown to be a method of choice for freezing in the lyophilization of a product with a high fill depth. In addition to being an effective method of freezing, it is most applicable for scaling up. An alternative approach is to add a certain amount of TBA to the formulation, if the TBA-formulation interaction or regulatory concerns can be demonstrated as not being an issue. An evaluation of vial size performed in this study showed that although utilizing large-diameter vials to reduce the fill depth can greatly shorten the cycle time of a single batch, it will substantially decrease the product throughput in a large-scale freeze-dryer.

  10. Slab Geometry and Segmentation on Seismogenic Subduction Zone; Insight from gravity gradients

    NASA Astrophysics Data System (ADS)

    Saraswati, A. T.; Mazzotti, S.; Cattin, R.; Cadio, C.

    2017-12-01

    Slab geometry is a key parameter to improve seismic hazard assessment in subduction zones. In many cases, information about structures beneath subduction are obtained from geophysical dedicated studies, including geodetic and seismic measurements. However, due to the lack of global information, both geometry and segmentation in seismogenic zone of many subductions remain badly-constrained. Here we propose an alternative approach based on satellite gravity observations. The GOCE (Gravity field and steady-state Ocean Circulation Explorer) mission enables to probe Earth deep mass structures from gravity gradients, which are more sensitive to spatial structure geometry and directional properties than classical gravitational data. Gravity gradients forward modeling of modeled slab is performed by using horizontal and vertical gravity gradient components to better determine slab geophysical model rather than vertical gradient only. Using polyhedron method, topography correction on gravity gradient signal is undertaken to enhance the anomaly signal of lithospheric structures. Afterward, we compare residual gravity gradients with the calculated signals associated with slab geometry. In this preliminary study, straightforward models are used to better understand the characteristic of gravity gradient signals due to deep mass sources. We pay a special attention to the delineation of slab borders and dip angle variations.

  11. TEMPERATURE-GRADIENT INCUBATOR FOR DETERMINING THE TEMPERATURE RANGE OF GROWTH OF MICROORGANISMS

    PubMed Central

    Elliott, R. Paul

    1963-01-01

    Elliott, R. Paul (U.S. Department of Agriculture, Albany, Calif.). Temperature-gradient incubator for determining the temperature range of growth of microorganisms. J. Bacteriol. 85:889–894. 1963.—The temperature-gradient incubator consists of an aluminum bar with troughs for media, with controlled temperatures at each end, and with insulation to prevent heat transfer. The resulting linear temperature gradient provides a means for determining minimal or maximal growth temperatures of microorganisms in any desired range and at any desired gradient. The operation of the incubator is unaffected by line-voltage variations or by ambient temperature. Media do not dehydrate seriously even during prolonged periods of operation. The incubator can be used to determine water activity of media by an adjustment to permit partial freezing. Either thermocouples or thermistors may be used to measure temperatures. Images PMID:14044959

  12. Stereo transparency and the disparity gradient limit

    NASA Technical Reports Server (NTRS)

    McKee, Suzanne P.; Verghese, Preeti

    2002-01-01

    Several studies (Vision Research 15 (1975) 583; Perception 9 (1980) 671) have shown that binocular fusion is limited by the disparity gradient (disparity/distance) separating image points, rather than by their absolute disparity values. Points separated by a gradient >1 appear diplopic. These results are sometimes interpreted as a constraint on human stereo matching, rather than a constraint on fusion. Here we have used psychophysical measurements on stereo transparency to show that human stereo matching is not constrained by a gradient of 1. We created transparent surfaces composed of many pairs of dots, in which each member of a pair was assigned a disparity equal and opposite to the disparity of the other member. For example, each pair could be composed of one dot with a crossed disparity of 6' and the other with uncrossed disparity of 6', vertically separated by a parametrically varied distance. When the vertical separation between the paired dots was small, the disparity gradient for each pair was very steep. Nevertheless, these opponent-disparity dot pairs produced a striking appearance of two transparent surfaces for disparity gradients ranging between 0.5 and 3. The apparent depth separating the two transparent planes was correctly matched to an equivalent disparity defined by two opaque surfaces. A test target presented between the two transparent planes was easily detected, indicating robust segregation of the disparities associated with the paired dots into two transparent surfaces with few mismatches in the target plane. Our simulations using the Tsai-Victor model show that the response profiles produced by scaled disparity-energy mechanisms can account for many of our results on the transparency generated by steep gradients.

  13. Identification, analysis and monitoring of risks of freezing affecting aircraft flying over the Guadarrama Mountains (Spain)

    NASA Astrophysics Data System (ADS)

    Fernández-González, Sergio; Sánchez, José Luis; Gascón, Estíbaliz; Merino, Andrés; Hermida, Lucía; López, Laura; Marcos, José Luis; García-Ortega, Eduardo

    2014-05-01

    Freezing is one of the main causes of aircraft accidents registered over the last few decades. This means it is very important to be able to predict this situation so that aircraft can change their routes to avoid freezing risk areas. Also, by using satellites it is possible to observe changes in the horizontal and vertical extension of cloud cover likely to cause freezing in real time as well as microphysical changes in the clouds. The METEOSAT Second Generation (MSG) makes it possible to create different red-green-blue (RGB) compositions that provide a large amount of information associated with the microphysics of clouds, in order to identify super-cooled water clouds that pose a high risk of freezing to aircraft. During the winter of 2011/12 in the Guadarrama Mountains, in the centre of the Iberian Peninsula, a series of scientific flights (conducted by INTA) were organised in order to study the cloud systems that affected this region during the winter. On the flight of the 1st of February 2012, the aircraft was affected by freezing after crossing over a mountain ridge with supercooled large drops (SLD). Although freezing was not expected during that day's flight, the orography caused a series of mesoscale factors that led to the appearance of localised freezing conditions. By analysing this case, we have been able to conclude that the use of satellite images makes it possible to monitor the risk of freezing, especially under specific mesoscale circumstances. Acknowledgements S. Fernández-González acknowledges the grant supported from the FPU program (AP 2010-2093). This study was supported by the following grants: GRANIMETRO (CGL2010-15930); MICROMETEO (IPT-310000-2010-22). The authors would like to thank the INTA for its scientific flights.

  14. SLAPex Freeze/Thaw 2015: The First Dedicated Soil Freeze/Thaw Airborne Campaign

    NASA Technical Reports Server (NTRS)

    Kim, Edward; Wu, Albert; DeMarco, Eugenia; Powers, Jarrett; Berg, Aaron; Rowlandson, Tracy; Freeman, Jacqueline; Gottfried, Kurt; Toose, Peter; Roy, Alexandre; hide

    2016-01-01

    Soil freezing and thawing is an important process in the terrestrial water, energy, and carbon cycles, marking the change between two very different hydraulic, thermal, and biological regimes. NASA's Soil Moisture Active/Passive (SMAP) mission includes a binary freeze/thaw data product. While there have been ground-based remote sensing field measurements observing soil freeze/thaw at the point scale, and airborne campaigns that observed some frozen soil areas (e.g., BOREAS), the recently-completed SLAPex Freeze/Thaw (F/T) campaign is the first airborne campaign dedicated solely to observing frozen/thawed soil with both passive and active microwave sensors and dedicated ground truth, in order to enable detailed process-level exploration of the remote sensing signatures and in situ soil conditions. SLAPex F/T utilized the Scanning L-band Active/Passive (SLAP) instrument, an airborne simulator of SMAP developed at NASA's Goddard Space Flight Center, and was conducted near Winnipeg, Manitoba, Canada, in October/November, 2015. Future soil moisture missions are also expected to include soil freeze/thaw products, and the loss of the radar on SMAP means that airborne radar-radiometer observations like those that SLAP provides are unique assets for freeze/thaw algorithm development. This paper will present an overview of SLAPex F/T, including descriptions of the site, airborne and ground-based remote sensing, ground truth, as well as preliminary results.

  15. Freezing of Gait Detection in Parkinson's Disease: A Subject-Independent Detector Using Anomaly Scores.

    PubMed

    Pham, Thuy T; Moore, Steven T; Lewis, Simon John Geoffrey; Nguyen, Diep N; Dutkiewicz, Eryk; Fuglevand, Andrew J; McEwan, Alistair L; Leong, Philip H W

    2017-11-01

    Freezing of gait (FoG) is common in Parkinsonian gait and strongly relates to falls. Current clinical FoG assessments are patients' self-report diaries and experts' manual video analysis. Both are subjective and yield moderate reliability. Existing detection algorithms have been predominantly designed in subject-dependent settings. In this paper, we aim to develop an automated FoG detector for subject independent. After extracting highly relevant features, we apply anomaly detection techniques to detect FoG events. Specifically, feature selection is performed using correlation and clusterability metrics. From a list of 244 feature candidates, 36 candidates were selected using saliency and robustness criteria. We develop an anomaly score detector with adaptive thresholding to identify FoG events. Then, using accuracy metrics, we reduce the feature list to seven candidates. Our novel multichannel freezing index was the most selective across all window sizes, achieving sensitivity (specificity) of (). On the other hand, freezing index from the vertical axis was the best choice for a single input, achieving sensitivity (specificity) of () for ankle and () for back sensors. Our subject-independent method is not only significantly more accurate than those previously reported, but also uses a much smaller window (e.g., versus ) and/or lower tolerance (e.g., versus ).Freezing of gait (FoG) is common in Parkinsonian gait and strongly relates to falls. Current clinical FoG assessments are patients' self-report diaries and experts' manual video analysis. Both are subjective and yield moderate reliability. Existing detection algorithms have been predominantly designed in subject-dependent settings. In this paper, we aim to develop an automated FoG detector for subject independent. After extracting highly relevant features, we apply anomaly detection techniques to detect FoG events. Specifically, feature selection is performed using correlation and clusterability metrics. From

  16. Vertical profile of tritium concentration in air during a chronic atmospheric HT release.

    PubMed

    Noguchi, Hiroshi; Yokoyama, Sumi

    2003-03-01

    The vertical profiles of tritium gas and tritiated water concentrations in air, which would have an influence on the assessment of tritium doses as well as on the environmental monitoring of tritium, were measured in a chronic tritium gas release experiment performed in Canada in 1994. While both of the profiles were rather uniform during the day because of atmospheric mixing, large gradients of the profiles were observed at night. The gradient coefficients of the profiles were derived from the measurements. Correlations were analyzed between the gradient coefficients and meteorological conditions: solar radiation, wind speed, and turbulent diffusivity. It was found that the solar radiation was highly correlated with the gradient coefficients of tritium gas and tritiated water profiles and that the wind speed and turbulent diffusivity showed weaker correlations with those of tritiated water profiles. A one-dimensional tritium transport model was developed to analyze the vertical diffusion of tritiated water re-emitted from the ground into the atmosphere. The model consists of processes of tritium gas deposition to soil including oxidation into tritiated water, reemission of tritiated water, dilution of tritiated water in soil by rain, and vertical diffusion of tritiated water in the atmosphere. The model accurately represents the accumulation of tritiated water in soil water and the time variations and vertical profiles of tritiated water concentrations in air.

  17. Effects of drop freezing on microphysics of an ascending cloud parcel under biomass burning conditions

    NASA Astrophysics Data System (ADS)

    Diehl, K.; Simmel, M.; Wurzler, S.

    There is some evidence that the initiation of warm rain is suppressed in clouds over regions with vegetation fires. Thus, the ice phase becomes important as another possibility to initiate precipitation. Numerical simulations were performed to investigate heterogeneous drop freezing for a biomass-burning situation. An air parcel model with a sectional two-dimensional description of the cloud microphysics was employed with parameterizations for immersion and contact freezing which consider the different ice nucleating efficiencies of various ice nuclei. Three scenarios were simulated resulting to mixed-phase or completely glaciated clouds. According to the high insoluble fraction of the biomass-burning particles drop freezing via immersion and contact modes was very efficient. The preferential freezing of large drops followed by riming (i.e. the deposition of liquid drops on ice particles) and the evaporation of the liquid drops (Bergeron-Findeisen process) caused a further decrease of the liquid drops' effective radius in higher altitudes. In turn ice particle sizes increased so that they could serve as germs for graupel or hailstone formation. The effects of ice initiation on the vertical cloud dynamics were fairly significant leading to a development of the cloud to much higher altitudes than in a warm cloud without ice formation.

  18. SENSITIVE TO FREEZING2 Aids in Resilience to Salt and Drought in Freezing-Sensitive Tomato

    DOE PAGES

    Wang, Kun; Hersh, Hope Lynn; Benning, Christoph

    2016-09-06

    SENSITIVE TO FREEZING2 (SFR2) is crucial for protecting chloroplast membranes following freezing in Arabidopsis (Arabidopsis thaliana). It has been shown that SFR2 homologs are present in all land plants, including freezing-sensitive species, raising the question of SFR2 function beyond freezing tolerance. Similar to freezing, salt and drought can cause dehydration. Thus, it is hypothesized that in freezing-sensitive plants SFR2 may play roles in their resilience to salt or drought. To test this hypothesis, SlSFR2 RNAi lines were generated in the cold/freezing-sensitive species tomato (Solanum lycopersicum [M82 cv]). Hypersensitivity to salt and drought of SlSFR2-RNAi lines was observed. Higher tolerance ofmore » wild-type tomatoes was correlated with the production of trigalactosyldiacylglycerol, a product of SFR2 activity. Tomato SFR2 in vitro activity is Mg 2+-dependent and its optimal pH is 7.5, similar to that of Arabidopsis SFR2, but the specific activity of tomato SFR2 in vitro is almost double that of Arabidopsis SFR2. When salt and drought stress were applied to Arabidopsis, no conditions could be identified at which SFR2 was induced prior to irreversibly impacting plant growth, suggesting that SFR2 protects Arabidopsis primarily against freezing. Discovery of tomato SFR2 function in drought and salt resilience provides further insights into general membrane lipid remodeling-based stress tolerance mechanisms and together with protection against freezing in freezing-resistant plants such as Arabidopsis, it adds lipid remodeling as a possible target for the engineering of abiotic stress-resilient crops.« less

  19. SENSITIVE TO FREEZING2 Aids in Resilience to Salt and Drought in Freezing-Sensitive Tomato

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Kun; Hersh, Hope Lynn; Benning, Christoph

    SENSITIVE TO FREEZING2 (SFR2) is crucial for protecting chloroplast membranes following freezing in Arabidopsis (Arabidopsis thaliana). It has been shown that SFR2 homologs are present in all land plants, including freezing-sensitive species, raising the question of SFR2 function beyond freezing tolerance. Similar to freezing, salt and drought can cause dehydration. Thus, it is hypothesized that in freezing-sensitive plants SFR2 may play roles in their resilience to salt or drought. To test this hypothesis, SlSFR2 RNAi lines were generated in the cold/freezing-sensitive species tomato (Solanum lycopersicum [M82 cv]). Hypersensitivity to salt and drought of SlSFR2-RNAi lines was observed. Higher tolerance ofmore » wild-type tomatoes was correlated with the production of trigalactosyldiacylglycerol, a product of SFR2 activity. Tomato SFR2 in vitro activity is Mg 2+-dependent and its optimal pH is 7.5, similar to that of Arabidopsis SFR2, but the specific activity of tomato SFR2 in vitro is almost double that of Arabidopsis SFR2. When salt and drought stress were applied to Arabidopsis, no conditions could be identified at which SFR2 was induced prior to irreversibly impacting plant growth, suggesting that SFR2 protects Arabidopsis primarily against freezing. Discovery of tomato SFR2 function in drought and salt resilience provides further insights into general membrane lipid remodeling-based stress tolerance mechanisms and together with protection against freezing in freezing-resistant plants such as Arabidopsis, it adds lipid remodeling as a possible target for the engineering of abiotic stress-resilient crops.« less

  20. Freezing Injury in Onion Bulb Cells

    PubMed Central

    Palta, Jiwan P.; Levitt, Jacob; Stadelmann, Eduard J.

    1977-01-01

    Onion (Allium cepa L.) bulbs were subjected for 12 days to either a moderate freeze (−4 C) or a severe freeze (−11 C). They were then thawed slowly over ice. During 7 to 12 days following the thaw, the injury progressed with time in the severely frozen bulbs, but appeared completely repaired in the moderately frozen bulbs. This was shown by the following post-thawing changes. Infiltration of the intercellular spaces increased from 80 to 90% to 100% after the severe freeze, and decreased from 30 to 50% to zero after the moderate freeze. All of the cells were alive immediately after thawing whether the freeze was moderate or severe. Corresponding to the infiltration results 7 to 12 days later, many to most were dead following the severe freeze, all were alive following the moderate freeze. The conductivity of the effusate from pieces of bulb tissue increased after the severe freezing, and decreased after the moderate freezing. The concentration of K+, total solutes, and sugars in the effusate paralleled the conductivity changes. Neither the pH of the effusate nor the permeability of the cells (as long as cells were living) to water was changed following either the severe or the moderate freezes. Some treatments of the thawed tissue following the severe freeze halted the progress of injury. The above results indicate that the semipermeable properties of the cell are uninjured but that the ion and sugar transport mechanism is damaged by freezing. Most likely the primary injury is to the active transport mechanism involved in their transport. It must be concluded that the final injury following freezing and thawing cannot be evaluated from the degree of infiltration or the conductivity of the effusate immediately after thawing, since injury may progress or recede following the thawing. PMID:16660101

  1. The role of calcium and calmodulin in freezing-induced freezing resistance of Populus tomentosa cuttings.

    PubMed

    Lin, Shan-Zhi; Zhang, Zhi-Yi; Lin, Yuan-Zhen; Zhang, Qian; Guo, Huan

    2004-02-01

    To explore the role of calcium-calmodulin messenger system in the transduction of low temperature signal in woody plants, Populus tomentosa cuttings after being treated with CaCl(2) (10 mmol/L), Ca(2+) chelator EGTA (3 mmol/L), Ca(2+) channel inhibitor LaCl(3) (100 mmol/L) or CaM antagonist CPZ (50 mmol/L) were used for freezing acclimation at -3 degrees C. The changes in the calmodulin (CaM) and malonaldehyde (MDA) contents, the activities of superoxide dismutase (SOD), peroxidase (POD) and Ca(2+)-dependent adenosinetriphosphatase (Ca(2+)-ATPase) of mitochondrial membrane as well as freezing resistance (expressed as LT(50)) of cuttings were investigated to elucidate the physiological mechanisms by which trees adapt to freezing. The results showed that freezing acclimation increased the CaM content, the activities of SOD, POD and Ca(2+)-ATPase of mitochondrial membrane as well as freezing resistance of cuttings, and decreased the MDA content as compared with control cuttings. Treatment with CaCl(2) at the time of freezing acclimation enhanced the effect of freezing acclimation on the above-mentioned indexes, but this enhancement was abolished by Ca(2+)chelator EGTA, Ca(2+) channel inhibitor LaCl(3) or CaM antagonist CPZ, indicating that the calcium-calmodulin messenger system was involved in the course of freezing resistance development. The presence of CaCl(2) at the same time of freezing acclimation also reduced the degree of decline in CaM content, and in SOD, POD and Ca(2+)-ATPase activities caused by freezing stress at -14 degrees C, and enhanced the level of increase in CaM content, and in SOD, POD and Ca(2+)-ATPase activity in the recovery periods at 25 degrees C . The change in CaM content was found to be closely correlated to the levels of SOD, POD and Ca(2+)-ATPase, and to the degree of freezing resistance of cuttings during freezing acclimation either with or without CaCl(2) treatment. It was suggested that the increase of CaM content induced by CaCl(2

  2. Freezing temperature of finger skin.

    PubMed

    Wilson, O; Goldman, R F; Molnar, G W

    1976-10-01

    In 45 subjects, 154 frostnips of the finger were induced by cooling in air at -15 degrees C with various wind speeds. The mean supercooled skin temperature at which frostnip appeared was -9.4 degrees C. The mean skin temperature rise due to heat of fusion at ice crystallization was 5.3 degrees C. The skin temperature rose to what was termed the apparent freezing point. The relation of this point to the supercooled skin temperature was analyzed for the three wind speeds used. An apparent freezing point for a condition of no supercooling was calculated, estimating the highest temperature at which skin freezes at a given wind speed. The validity of the obtained differences in apparent freezing point was tested by an analysis of covariance. Although not statistically significant, the data suggest that the apparent freezing point with no supercooling decreases with increasing wind velocity. The highest calculated apparent freezing point at -15 degrees C and 6.8 m/s was 1.2 degrees C lower than the true freezing point for skin previously determined in brine, which is a statistically significant difference.

  3. Dip and anisotropy effects on flow using a vertically skewed model grid.

    PubMed

    Hoaglund, John R; Pollard, David

    2003-01-01

    Darcy flow equations relating vertical and bedding-parallel flow to vertical and bedding-parallel gradient components are derived for a skewed Cartesian grid in a vertical plane, correcting for structural dip given the principal hydraulic conductivities in bedding-parallel and bedding-orthogonal directions. Incorrect-minus-correct flow error results are presented for ranges of structural dip (0 < or = theta < or = 90) and gradient directions (0 < or = phi < or = 360). The equations can be coded into ground water models (e.g., MODFLOW) that can use a skewed Cartesian coordinate system to simulate flow in structural terrain with deformed bedding planes. Models modified with these equations will require input arrays of strike and dip, and a solver that can handle off-diagonal hydraulic conductivity terms.

  4. Spatial patterns of wet season precipitation vertical gradients on the Tibetan Plateau and the surroundings.

    PubMed

    Cuo, Lan; Zhang, Yongxin

    2017-07-11

    The Tibetan Plateau and the surrounding (TPS) with its vast land mass and high elevation affects regional climate and weather. The TPS is also the headwater of 9 major Asian rivers that provide fresh water for 1.65 billion people and many ecosystems, with wet season (May-September) precipitation being the critical component of the fresh water. Using station observations, ERA-Interim and MERRA2 reanalysis, we find that wet season precipitation displays vertical gradients (i.e., changes with elevation) that vary within the region on the TPS. The decrease of precipitation with elevation occurs in the interior TPS with elevation larger than 4000 m, little or no change over the southeastern TPS, and increase elsewhere. The increase of precipitation with elevation is caused by increasing convective available potential energy (CAPE) and decreasing lifting condensation level (LCL) with elevation overwhelming the effects of decreasing total column water vapor (TCWV) with elevation. The decreasing precipitation with elevation is due to the combined effects of increasing LCL and decreasing TCWV. LCL and CAPE play a more important role than TCWV in determining the spatial patterns. These findings are important for hydrology study in observation scarce mountainous areas, water resources and ecosystem managements in the region.

  5. The Freezing Bomb

    ERIC Educational Resources Information Center

    Mills, Allan

    2010-01-01

    The extreme pressures that are generated when water freezes were traditionally demonstrated by sealing a small volume in a massive cast iron "bomb" and then surrounding it with a freezing mixture of ice and salt. This vessel would dramatically fail by brittle fracture, but no quantitative measurement of bursting pressure was available. Calculation…

  6. Fundamental Technical Elements of Freeze-fracture/Freeze-etch in Biological Electron Microscopy

    EPA Science Inventory

    Freeze-fracture/freeze-etch describes a process whereby specimens, typically biological or nanomaterial in nature, are frozen, fractured, and replicated to generate a carbon/platinum "cast" intended for examination by transmission electron microscopy. Specimens are subjected to u...

  7. Fundamental technical elements of freeze-fracture/freeze-etch in biological electron microscopy.

    PubMed

    Carson, Johnny L

    2014-09-11

    Freeze-fracture/freeze-etch describes a process whereby specimens, typically biological or nanomaterial in nature, are frozen, fractured, and replicated to generate a carbon/platinum "cast" intended for examination by transmission electron microscopy. Specimens are subjected to ultrarapid freezing rates, often in the presence of cryoprotective agents to limit ice crystal formation, with subsequent fracturing of the specimen at liquid nitrogen cooled temperatures under high vacuum. The resultant fractured surface is replicated and stabilized by evaporation of carbon and platinum from an angle that confers surface three-dimensional detail to the cast. This technique has proved particularly enlightening for the investigation of cell membranes and their specializations and has contributed considerably to the understanding of cellular form to related cell function. In this report, we survey the instrument requirements and technical protocol for performing freeze-fracture, the associated nomenclature and characteristics of fracture planes, variations on the conventional procedure, and criteria for interpretation of freeze-fracture images. This technique has been widely used for ultrastructural investigation in many areas of cell biology and holds promise as an emerging imaging technique for molecular, nanotechnology, and materials science studies.

  8. Metallicity gradient of the thick disc progenitor at high redshift

    NASA Astrophysics Data System (ADS)

    Kawata, Daisuke; Allende Prieto, Carlos; Brook, Chris B.; Casagrande, Luca; Ciucă, Ioana; Gibson, Brad K.; Grand, Robert J. J.; Hayden, Michael R.; Hunt, Jason A. S.

    2018-01-01

    We have developed a novel Markov Chain Monte Carlo chemical 'painting' technique to explore possible radial and vertical metallicity gradients for the thick disc progenitor. In our analysis, we match an N-body simulation to the data from the Apache Point Observatory Galactic Evolution Experiment survey. We assume that the thick disc has a constant scaleheight and has completed its formation at an early epoch, after which time radial mixing of its stars has taken place. Under these assumptions, we find that the initial radial metallicity gradient of the thick disc progenitor should not be negative, but either flat or even positive, to explain the current negative vertical metallicity gradient of the thick disc. Our study suggests that the thick disc was built-up in an inside-out and upside-down fashion, and older, smaller and thicker populations are more metal poor. In this case, star-forming discs at different epochs of the thick disc formation are allowed to have different radial metallicity gradients, including a negative one, which helps to explain a variety of slopes observed in high-redshift disc galaxies. This scenario helps to explain the positive slope of the metallicity-rotation velocity relation observed for the Galactic thick disc. On the other hand, radial mixing flattens the slope of an existing gradient.

  9. The effect of density gradients on hydrometers

    NASA Astrophysics Data System (ADS)

    Heinonen, Martti; Sillanpää, Sampo

    2003-05-01

    Hydrometers are simple but effective instruments for measuring the density of liquids. In this work, we studied the effect of non-uniform density of liquid on a hydrometer reading. The effect induced by vertical temperature gradients was investigated theoretically and experimentally. A method for compensating for the effect mathematically was developed and tested with experimental data obtained with the MIKES hydrometer calibration system. In the tests, the method was found reliable. However, the reliability depends on the available information on the hydrometer dimensions and density gradients.

  10. A new method for mapping variability in vertical seepage flux in streambeds

    NASA Astrophysics Data System (ADS)

    Chen, Xunhong; Song, Jinxi; Cheng, Cheng; Wang, Deming; Lackey, Susan O.

    2009-05-01

    A two-step approach was used to measure the flux across the water-sediment interface in river channels. A hollow tube was pressed into the streambed and an in situ sediment column of the streambed was created inside the tube. The hydraulic gradient between the two ends of the sediment column was measured. The vertical hydraulic conductivity of the sediment column was determined using a falling-head permeameter test in the river. Given the availability of the hydraulic gradient and vertical hydraulic conductivity of the streambed, Darcy’s law was used to calculate the specific discharge. This approach was applied to the Elkhorn River and one tributary in northeastern Nebraska, USA. The results suggest that the magnitude of the vertical flux varied greatly within a short distance. Furthermore, the flux can change direction from downward to upward between two locations only several meters apart. This spatial pattern of variation probably represents the inflow and outflow within the hyporheic zone, not the regional ambient flow systems. In this study, a thermal infrared camera was also used to detect the discharge locations of groundwater in the streambed. After the hydraulic gradient and the vertical hydraulic conductivity were estimated from the groundwater spring, the discharge rate was calculated.

  11. The role of the meridional sea surface temperature gradient in controlling the Caribbean low-level jet

    NASA Astrophysics Data System (ADS)

    Maldonado, Tito; Rutgersson, Anna; Caballero, Rodrigo; Pausata, Francesco S. R.; Alfaro, Eric; Amador, Jorge

    2017-06-01

    The Caribbean low-level jet (CLLJ) is an important modulator of regional climate, especially precipitation, in the Caribbean and Central America. Previous work has inferred, due to their semiannual cycle, an association between CLLJ strength and meridional sea surface temperature (SST) gradients in the Caribbean Sea, suggesting that the SST gradients may control the intensity and vertical shear of the CLLJ. In addition, both the horizontal and vertical structure of the jet have been related to topographic effects via interaction with the mountains in Northern South America (NSA), including funneling effects and changes in the meridional geopotential gradient. Here we test these hypotheses, using an atmospheric general circulation model to perform a set of sensitivity experiments to examine the impact of both SST gradients and topography on the CLLJ. In one sensitivity experiment, we remove the meridional SST gradient over the Caribbean Sea and in the other, we flatten the mountains over NSA. Our results show that the SST gradient and topography have little or no impact on the jet intensity, vertical, and horizontal wind shears, contrary to previous works. However, our findings do not discount a possible one-way coupling between the SST and the wind over the Caribbean Sea through friction force. We also examined an alternative approach based on barotropic instability to understand the CLLJ intensity, vertical, and horizontal wind shears. Our results show that the current hypothesis about the CLLJ must be reviewed in order to fully understand the atmospheric dynamics governing the Caribbean region.

  12. Wide-range stiffness gradient PVA/HA hydrogel to investigate stem cell differentiation behavior.

    PubMed

    Oh, Se Heang; An, Dan Bi; Kim, Tae Ho; Lee, Jin Ho

    2016-04-15

    Although stiffness-controllable substrates have been developed to investigate the effect of stiffness on cell behavior and function, the use of separate substrates with different degrees of stiffness, substrates with a narrow range stiffness gradient, toxicity of residues, different surface composition, complex fabrication procedures/devices, and low cell adhesion are still considered as hurdles of conventional techniques. In this study, a cylindrical polyvinyl alcohol (PVA)/hyaluronic acid (HA) hydrogel with a wide-range stiffness gradient (between ∼20kPa and ∼200kPa) and cell adhesiveness was prepared by a liquid nitrogen (LN2)-contacting gradual freezing-thawing method that does not use any additives or specific devices to produce the stiffness gradient hydrogel. From an in vitro cell culture using the stiffness gradient PVA/HA hydrogel, it was observed that human bone marrow mesenchymal stem cells have favorable stiffness ranges for induction of differentiation into specific cell types (∼20kPa for nerve cell, ∼40kPa for muscle cell, ∼80kPa for chondrocyte, and ∼190kPa for osteoblast). The PVA/HA hydrogel with a wide range of stiffness spectrum can be a useful tool for basic studies related with the stem cell differentiation, cell reprogramming, cell migration, and tissue regeneration in terms of substrate stiffness. It is postulated that the stiffness of the extracellular matrix influences cell behavior. To prove this concept, various techniques to prepare substrates with a stiffness gradient have been developed. However, the narrow ranges of stiffness gradient and complex fabrication procedures/devices are still remained as limitations. Herein, we develop a substrate (hydrogel) with a wide-range stiffness gradient using a gradual freezing-thawing method which does not need specific devices to produce a stiffness gradient hydrogel. From cell culture experiments using the hydrogel, it is observed that human bone marrow mesenchymal stem cells have

  13. Freeze-drying process design by manometric temperature measurement: design of a smart freeze-dryer.

    PubMed

    Tang, Xiaolin Charlie; Nail, Steven L; Pikal, Michael J

    2005-04-01

    To develop a procedure based on manometric temperature measurement (MTM) and an expert system for good practices in freeze drying that will allow development of an optimized freeze-drying process during a single laboratory freeze-drying experiment. Freeze drying was performed with a FTS Dura-Stop/Dura-Top freeze dryer with the manometric temperature measurement software installed. Five percent solutions of glycine, sucrose, or mannitol with 2 ml to 4 ml fill in 5 ml vials were used, with all vials loaded on one shelf. Details of freezing, optimization of chamber pressure, target product temperature, and some aspects of secondary drying are determined by the expert system algorithms. MTM measurements were used to select the optimum shelf temperature, to determine drying end points, and to evaluate residual moisture content in real-time. MTM measurements were made at 1 hour or half-hour intervals during primary drying and secondary drying, with a data collection frequency of 4 points per second. The improved MTM equations were fit to pressure-time data generated by the MTM procedure using Microcal Origin software to obtain product temperature and dry layer resistance. Using heat and mass transfer theory, the MTM results were used to evaluate mass and heat transfer rates and to estimate the shelf temperature required to maintain the target product temperature. MTM product dry layer resistance is accurate until about two-thirds of total primary drying time is over, and the MTM product temperature is normally accurate almost to the end of primary drying provided that effective thermal shielding is used in the freeze-drying process. The primary drying times can be accurately estimated from mass transfer rates calculated very early in the run, and we find the target product temperature can be achieved and maintained with only a few adjustments of shelf temperature. The freeze-dryer overload conditions can be estimated by calculation of heat/mass flow at the target product

  14. Representative Values of Icing-Related Variables Aloft in Freezing Rain and Freezing Drizzle

    DOT National Transportation Integrated Search

    1996-03-01

    Radiosonde and surface observations in freezing rain (ZR) and freezing drizzle (ZL), and a limited number of aircraft measurements in ZR, have been examined for information on the magnitude and altitude dependence of meteorological variables associat...

  15. Freeze-Casting Produces a Graphene Oxide Aerogel with a Radial and Centrosymmetric Structure.

    PubMed

    Wang, Chunhui; Chen, Xiong; Wang, Bin; Huang, Ming; Wang, Bo; Jiang, Yi; Ruoff, Rodney S

    2018-05-14

    We report the assembly of graphene oxide (G-O) building blocks into a vertical and radially aligned structure by a bidirectional freeze-casting approach. The crystallization of water to ice assembles the G-O sheets into a structure, a G-O aerogel whose local structure mimics turbine blades. The centimeter-scale radiating structure in this aerogel has many channels whose width increases with distance from the center. This was achieved by controlling the formation of the ice crystals in the aqueous G-O dispersion that grew radially in the shape of lamellae during freezing. Because the shape and size of ice crystals is influenced by the G-O sheets, different additives (ethanol, cellulose nanofibers, and chitosan) that can form hydrogen bonds with H 2 O were tested and found to affect the interaction between the G-O and formation of ice crystals, producing ice crystals with different shapes. A G-O/chitosan aerogel with a spiral pattern was also obtained. After chemical reduction of G-O, our aerogel exhibited elasticity and absorption capacity superior to that of graphene aerogels with "traditional" pore structures made by conventional freeze-casting. This methodology can be expanded to many other configurations and should widen the use of G-O (and reduced G-O and "graphenic") aerogels.

  16. SENSITIVE TO FREEZING2 Aids in Resilience to Salt and Drought in Freezing-Sensitive Tomato1[OPEN

    PubMed Central

    Hersh, Hope Lynn

    2016-01-01

    SENSITIVE TO FREEZING2 (SFR2) is crucial for protecting chloroplast membranes following freezing in Arabidopsis (Arabidopsis thaliana). It has been shown that SFR2 homologs are present in all land plants, including freezing-sensitive species, raising the question of SFR2 function beyond freezing tolerance. Similar to freezing, salt and drought can cause dehydration. Thus, it is hypothesized that in freezing-sensitive plants SFR2 may play roles in their resilience to salt or drought. To test this hypothesis, SlSFR2 RNAi lines were generated in the cold/freezing-sensitive species tomato (Solanum lycopersicum [M82 cv]). Hypersensitivity to salt and drought of SlSFR2-RNAi lines was observed. Higher tolerance of wild-type tomatoes was correlated with the production of trigalactosyldiacylglycerol, a product of SFR2 activity. Tomato SFR2 in vitro activity is Mg2+-dependent and its optimal pH is 7.5, similar to that of Arabidopsis SFR2, but the specific activity of tomato SFR2 in vitro is almost double that of Arabidopsis SFR2. When salt and drought stress were applied to Arabidopsis, no conditions could be identified at which SFR2 was induced prior to irreversibly impacting plant growth, suggesting that SFR2 protects Arabidopsis primarily against freezing. Discovery of tomato SFR2 function in drought and salt resilience provides further insights into general membrane lipid remodeling-based stress tolerance mechanisms and together with protection against freezing in freezing-resistant plants such as Arabidopsis, it adds lipid remodeling as a possible target for the engineering of abiotic stress-resilient crops. PMID:27600812

  17. Freezing: an underutilized food safety technology?

    PubMed

    Archer, Douglas L

    2004-01-15

    Freezing is an ancient technology for preserving foods. Freezing halts the activities of spoilage microorganisms in and on foods and can preserve some microorganisms for long periods of time. Frozen foods have an excellent overall safety record. The few outbreaks of food-borne illness associated with frozen foods indicate that some, but not all human pathogens are killed by commercial freezing processes. Freezing kills microorganisms by physical and chemical effects and possibly through induced genetic changes. Research is needed to better understand the physical and chemical interactions of various food matrices with the microbial cell during freezing and holding at frozen temperatures. The literature suggests that many pathogenic microorganisms may be sublethally injured by freezing, so research should be done to determine how to prevent injured cells from resuscitating and becoming infectious. Studies on the genetics of microbial stress suggest that the induction of resistance to specific stresses may be counteracted by, for example, simple chemicals. Research is needed to better understand how resistance to the lethal effect of freezing is induced in human pathogens and means by which it can be counteracted in specific foods. Through research, it seems possible that freezing may in the future be used to reliably reduce populations of food-borne pathogens as well as to preserve foods.

  18. Freezing and thawing or freezing, thawing, and aging effects on beef tenderness

    USDA-ARS?s Scientific Manuscript database

    The objective of this study was to determine the effect of freezing and thawing or freezing and thawing with an additional aging period after frozen storage on the tenderness of longissimus lumborum (LL) and semitendinosus (ST) steaks relative to aged, fresh steaks. Left-side LL and ST (n=35 each) ...

  19. Subsurface temperatures and geothermal gradients on the North Slope, Alaska

    USGS Publications Warehouse

    Collett, Timothy S.; Bird, Kenneth J.; Magoon, Leslie B.

    1989-01-01

    Geothermal gradients as interpreted from a series of high-resolution stabilized well-bore-temperature surveys from 46 North Slope, Alaska, wells vary laterally and vertically throughout the near-surface sediment (0-2,000 m). The data from these surveys have been used in conjunction with depths of ice-bearing permafrost, as interpreted from 102 well logs, to project geothermal gradients within and below the ice-bearing permafrost sequence. The geothermal gradients calculated from the projected temperature profiles are similar to the geothermal gradients measured in the temperature surveys. Measured and projected geothermal gradients in the ice-bearing permafrost sequence range from 1.5??C/100m in the Prudhoe Bay area to 5.1??C/100m in the National Petroleum Reserve in Alaska (NPRA).

  20. New methods for interpretation of magnetic vector and gradient tensor data I: eigenvector analysis and the normalised source strength

    NASA Astrophysics Data System (ADS)

    Clark, David A.

    2012-09-01

    Acquisition of magnetic gradient tensor data is likely to become routine in the near future. New methods for inverting gradient tensor surveys to obtain source parameters have been developed for several elementary, but useful, models. These include point dipole (sphere), vertical line of dipoles (narrow vertical pipe), line of dipoles (horizontal cylinder), thin dipping sheet, and contact models. A key simplification is the use of eigenvalues and associated eigenvectors of the tensor. The normalised source strength (NSS), calculated from the eigenvalues, is a particularly useful rotational invariant that peaks directly over 3D compact sources, 2D compact sources, thin sheets and contacts, and is independent of magnetisation direction. In combination the NSS and its vector gradient determine source locations uniquely. NSS analysis can be extended to other useful models, such as vertical pipes, by calculating eigenvalues of the vertical derivative of the gradient tensor. Inversion based on the vector gradient of the NSS over the Tallawang magnetite deposit obtained good agreement between the inferred geometry of the tabular magnetite skarn body and drill hole intersections. Besides the geological applications, the algorithms for the dipole model are readily applicable to the detection, location and characterisation (DLC) of magnetic objects, such as naval mines, unexploded ordnance, shipwrecks, archaeological artefacts, and buried drums.

  1. On the metallicity gradients of the Galactic disk as revealed by LSS-GAC red clump stars

    NASA Astrophysics Data System (ADS)

    Huang, Yang; Liu, Xiao-Wei; Zhang, Hua-Wei; Yuan, Hai-Bo; Xiang, Mao-Sheng; Chen, Bing-Qiu; Ren, Juan-Juan; Sun, Ning-Chen; Wang, Chun; Zhang, Yong; Hou, Yong-Hui; Wang, Yue-Fei; Yang, Ming

    2015-08-01

    Using a sample of over 70 000 red clump (RC) stars with 5%-10% distance accuracy selected from the LAMOST Spectroscopic Survey of the Galactic Anti-center (LSS-GAC), we study the radial and vertical gradients of the Galactic disk(s) mainly in the anti-center direction, covering a significant volume of the disk in the range of projected Galactocentric radius 7 ≤ RGC ≤ 14 kpc and height from the Galactic midplane 0 ≤ |Z| ≤ 3 kpc. Our analysis shows that both the radial and vertical metallicity gradients are negative across much of the volume of the disk that is probed, and they exhibit significant spatial variations. Near the solar circle (7 ≤ RGC ≤ 115 kpc), the radial gradient has a moderately steep, negative slope of -0.08 dex kpc-1 near the midplane (|Z| < 0.1 kpc), and the slope flattens with increasing |Z|. In the outer disk (11.5 < RGC ≤ 14 kpc), the radial gradients have an essentially constant, much less steep slope of -0.01 dex kpc-1 at all heights above the plane, suggesting that the outer disk may have experienced an evolutionary path different from that of the inner disk. The vertical gradients are found to flatten largely with increasing RGC. However, the vertical gradient of the lower disk (0 ≤ |Z| ≤ 1 kpc) is found to flatten with RGC quicker than that of the upper disk (1 < |Z| ≤ 3 kpc). Our results should provide strong constraints on the theory of disk formation and evolution, as well as the underlying physical processes that shape the disk (e.g. gas flows, radial migration, and internal and external perturbations).

  2. Evidence for a freezing tolerance-growth rate trade-off in the live oaks (Quercus series Virentes) across the tropical-temperate divide.

    PubMed

    Koehler, Kari; Center, Alyson; Cavender-Bares, Jeannine

    2012-02-01

    • It has long been hypothesized that species are limited to the north by minimum temperature and to the south by competition, resulting in a trade-off between freezing tolerance and growth rate. We investigated the extent to which the climatic origins of populations from four live oak species (Quercus series Virentes) were associated with freezing tolerance and growth rate, and whether species fitted a model of locally adapted populations, each with narrow climatic tolerances, or of broadly adapted populations with wide climatic tolerances. • Acorns from populations of four species across a tropical-temperate gradient were grown under common tropical and temperate conditions. Growth rate, seed mass, and leaf and stem freezing traits were compared with source minimum temperatures. • Maximum growth rates under tropical conditions were negatively correlated with freezing tolerance under temperate conditions. The minimum source temperature predicted the freezing tolerance of populations under temperate conditions. The tropical species Q. oleoides was differentiated from the three temperate species, and variation among species was greater than among populations. • The trade-off between freezing tolerance and growth rate supports the range limit hypothesis. Limited variation within species indicates that the distributions of species may be driven more strongly by broad climatic factors than by highly local conditions. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

  3. Observations of wave-induced pore pressure gradients and bed level response on a surf zone sandbar

    NASA Astrophysics Data System (ADS)

    Anderson, Dylan; Cox, Dan; Mieras, Ryan; Puleo, Jack A.; Hsu, Tian-Jian

    2017-06-01

    Horizontal and vertical pressure gradients may be important physical mechanisms contributing to onshore sediment transport beneath steep, near-breaking waves in the surf zone. A barred beach was constructed in a large-scale laboratory wave flume with a fixed profile containing a mobile sediment layer on the crest of the sandbar. Horizontal and vertical pore pressure gradients were obtained by finite differences of measurements from an array of pressure transducers buried within the upper several centimeters of the bed. Colocated observations of erosion depth were made during asymmetric wave trials with wave heights between 0.10 and 0.98 m, consistently resulting in onshore sheet flow sediment transport. The pore pressure gradient vector within the bed exhibited temporal rotations during each wave cycle, directed predominantly upward under the trough and then rapidly rotating onshore and downward as the wavefront passed. The magnitude of the pore pressure gradient during each phase of rotation was correlated with local wave steepness and relative depth. Momentary bed failures as deep as 20 grain diameters were coincident with sharp increases in the onshore-directed pore pressure gradients, but occurred at horizontal pressure gradients less than theoretical critical values for initiation of the motion for compact beds. An expression combining the effects of both horizontal and vertical pore pressure gradients with bed shear stress and soil stability is used to determine that failure of the bed is initiated at nonnegligible values of both forces.Plain Language SummaryThe pressure <span class="hlt">gradient</span> present within the seabed beneath breaking waves may be an important physical mechanism transporting sediment. A large-scale laboratory was used to replicate realistic surfzone conditions in controlled tests, allowing for horizontal and <span class="hlt">vertical</span> pressure <span class="hlt">gradient</span> magnitudes and the resulting sediment bed response to be observed with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29432761','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29432761"><span>Application of the Quality by Design Approach to the <span class="hlt">Freezing</span> Step of <span class="hlt">Freeze</span>-Drying: Building the Design Space.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Arsiccio, Andrea; Pisano, Roberto</p> <p>2018-06-01</p> <p>The present work shows a rational method for the development of the <span class="hlt">freezing</span> step of a <span class="hlt">freeze</span>-drying cycle. The current approach to the selection of <span class="hlt">freezing</span> conditions is still empirical and nonsystematic, thus resulting in poor robustness of control strategy. The final aim of this work is to fill this gap, describing a rational procedure, based on mathematical modeling, for properly choosing the <span class="hlt">freezing</span> conditions. Mechanistic models are used for the prediction of temperature profiles during <span class="hlt">freezing</span> and dimension of ice crystals being formed. Mathematical description of the drying phase of <span class="hlt">freeze</span>-drying is also coupled with the results obtained by <span class="hlt">freezing</span> models, thus providing a comprehensive characterization of the lyophilization process. In this framework, deep understanding of the phenomena involved is required, and according to the Quality by Design approach, this knowledge can be used to build the design space. The step-by-step procedure for building the design space for <span class="hlt">freezing</span> is thus described, and examples of applications are provided. The calculated design space is validated upon experimental data, and we show that it allows easy control of the <span class="hlt">freezing</span> process and fast selection of appropriate operating conditions. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12844203','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12844203"><span><span class="hlt">Freezing</span> curve-based monitoring to quickly evaluate the viability of biological materials subject to <span class="hlt">freezing</span> or thermal injury.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Jing; Zhou, Yi-Xin</p> <p>2003-09-01</p> <p>This paper is aimed at investigating the roles of <span class="hlt">freezing</span> dynamics of a liquid droplet to characterize the properties of the material. In particular, <span class="hlt">freezing</span> curve-based monitoring was proposed to quickly evaluate the viability of biological materials subject to <span class="hlt">freezing</span>, re-warming, or other kinds of injury, which is an extremely important issue in practices such as cryobiology, hyperthermia, or freshness evaluation of bio-samples. An integrated micro analysis device was fabricated which is simple in structure and cheap to make. Preliminary <span class="hlt">freezing</span> results demonstrated that minor changes in a biological material due to <span class="hlt">freezing</span> or warming injury might result in a significant deviation of its <span class="hlt">freezing</span> curve from that of the intact biomaterials. Several potential thermal indexes to quantify the material features were pointed out. Further, experiments were performed on some <span class="hlt">freezing</span> and thawing processes of small amount of water on a cooling surface to test the effects of droplet sizes, measurement sites, cooling strength, and cooling geometry, etc., on the <span class="hlt">freezing</span> responses of a water droplet. Their implementation in developing a new micro analysis system were suggested. This <span class="hlt">freezing</span> curve-based monitoring method may open a new strategy for the evaluation of biomaterials subject to destruction in diverse fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26585223','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26585223"><span>Cavitation and water fluxes driven by ice water potential in Juglans regia during <span class="hlt">freeze</span>-thaw cycles.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Charra-Vaskou, Katline; Badel, Eric; Charrier, Guillaume; Ponomarenko, Alexandre; Bonhomme, Marc; Foucat, Loïc; Mayr, Stefan; Améglio, Thierry</p> <p>2016-02-01</p> <p><span class="hlt">Freeze</span>-thaw cycles induce major hydraulic changes due to liquid-to-ice transition within tree stems. The very low water potential at the ice-liquid interface is crucial as it may cause lysis of living cells as well as water fluxes and embolism in sap conduits, which impacts whole tree-water relations. We investigated water fluxes induced by ice formation during <span class="hlt">freeze</span>-thaw cycles in Juglans regia L. stems using four non-invasive and complementary approaches: a microdendrometer, magnetic resonance imaging, X-ray microtomography, and ultrasonic acoustic emissions analysis. When the temperature dropped, ice nucleation occurred, probably in the cambium or pith areas, inducing high water potential <span class="hlt">gradients</span> within the stem. The water was therefore redistributed within the stem toward the ice front. We could thus observe dehydration of the bark's living cells leading to drastic shrinkage of this tissue, as well as high tension within wood conduits reaching the cavitation threshold in sap vessels. Ultrasonic emissions, which were strictly emitted only during <span class="hlt">freezing</span>, indicated cavitation events (i.e. bubble formation) following ice formation in the xylem sap. However, embolism formation (i.e. bubble expansion) in stems was observed only on thawing via X-ray microtomography for the first time on the same sample. Ultrasonic emissions were detected during <span class="hlt">freezing</span> and were not directly related to embolism formation. These results provide new insights into the complex process and dynamics of water movements and ice formation during <span class="hlt">freeze</span>-thaw cycles in tree stems. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26291340','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26291340"><span>Contact <span class="hlt">Freezing</span> of Water by Salts.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Niehaus, Joseph; Cantrell, Will</p> <p>2015-09-03</p> <p>Water is unlikely to crystallize homogeneously at temperatures greater than -34 °C. <span class="hlt">Freezing</span> at higher temperatures is heterogeneous-catalyzed by the presence of a second substance. If that substance is at an air-water interface, then the mode is called contact <span class="hlt">freezing</span>, and it typically will trigger nucleation at a higher temperature than if the substance were wholly immersed within the liquid. We find that the impact of salt particles initiates <span class="hlt">freezing</span> in experiments using water droplets at supercoolings of 9 to 16 °C. These results show that contact <span class="hlt">freezing</span> nuclei need not be effective as immersion mode nuclei. We discuss our results in the context of proposed mechanisms of contact <span class="hlt">freezing</span>. Finally, we use the time scales for diffusion of heat and of ions and the propagation of a sound wave through the droplet to estimate that contact <span class="hlt">freezing</span> occurs within 10 ns of impact.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/21538','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/21538"><span>Seasonal differences in <span class="hlt">freezing</span> tolerance of yellow-cedar and western hemlock trees at a site affected by yellow-cedar decline</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Paul G. Schaberg; Paul E. Hennon; Amore, David V. D; Gary J. Hawley; Catherine H. Borer; Catherine H. Borer</p> <p>2005-01-01</p> <p>To assess whether inadequate cold hardiness could be a contributor to yellow-cedar (Chamaecyparis nootkatensis (D. Don) Spach) decline, we measured the <span class="hlt">freezing</span> tolerance of foliage from yellow-cedar trees in closed-canopy (nondeclining) and open-canopy (declining at elevations below 130 m) stands at three sites along an elevational <span class="hlt">gradient</span> in the heart of the decline...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28362231','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28362231"><span>Cognitive Factors Affecting <span class="hlt">Freeze</span>-like Behavior in Humans.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Alban, Michael W; Pocknell, Victoria</p> <p>2017-01-01</p> <p>Contemporary research on survival-related defensive behaviors has identified physiological markers of <span class="hlt">freeze</span>/flight/fight. Our research focused on cognitive factors associated with <span class="hlt">freeze</span>-like behavior in humans. Study 1 tested if an explicit decision to <span class="hlt">freeze</span> is associated with the psychophysiological state of <span class="hlt">freezing</span>. Heart rate deceleration occurred when participants chose to <span class="hlt">freeze</span>. Study 2 varied the efficacy of <span class="hlt">freezing</span> relative to other defense options and found "<span class="hlt">freeze</span>" was responsive to variations in the perceived effectiveness of alternative actions. Study 3 tested if individual differences in motivational orientation affect preference for a "<span class="hlt">freeze</span>" option when the efficacy of options is held constant. A trend in the predicted direction suggested that naturally occurring cognitions led loss-avoiders to select "<span class="hlt">freeze</span>" more often than reward-seekers. In combination, our attention to the cognitive factors affecting <span class="hlt">freeze</span>-like behavior in humans represents a preliminary step in addressing an important but neglected research area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.water.usgs.gov/wri014028/','USGSPUBS'); return false;" href="http://pubs.water.usgs.gov/wri014028/"><span><span class="hlt">Vertical</span> <span class="hlt">gradients</span> in water chemistry in the central High Plains aquifer, southwestern Kansas and Oklahoma panhandle, 1999</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>McMahon, Peter B.</p> <p>2001-01-01</p> <p>The central High Plains aquifer is the primary source of water for domestic, industrial, and irrigation uses in parts of Colorado, Kansas, New Mexico, Oklahoma, and Texas. Water-level declines of more than 100 feet in some areas of the aquifer have increased the demand for water deeper in the aquifer. The maximum saturated thickness of the aquifer ranged from 500 to 600 feet in 1999. As the demand for deeper water increases, it becomes increasingly important for resource managers to understand how the quality of water in the aquifer changes with depth. In 1998?99, 18 monitoring wells at nine sites in southwestern Kansas and the Oklahoma Panhandle were completed at various depths in the central High Plains aquifer, and one monitoring well was completed in sediments of Permian age underlying the aquifer. Water samples were collected once from each well in 1999 to measure <span class="hlt">vertical</span> <span class="hlt">gradients</span> in water chemistry in the aquifer. Tritium concentrations measured in ground water indicate that water samples collected in the upper 30 feet of the aquifer were generally recharged within the last 50 years, whereas all of the water samples collected at depths more than 30 feet below the water table were recharged more than 50 years ago. Dissolved oxygen was present throughout the aquifer, with concentrations ranging from 1.7 to 8.4 mg/L. Water in the central High Plains aquifer was predominantly a calcium-bicarbonate type that exhibited little variability in concentrations of dissolved solids with depth (290 to 642 mg/L). Exceptions occurred in some areas where there had been upward movement of mineralized water from underlying sediments of Permian age and areas where there had been downward movement of mineralized Arkansas River water to the aquifer. Calcium-sulfate and sodium-chloride waters dominated and concentrations of dissolved solids were elevated (862 to 4,030 mg/L) near the base of the aquifer in the areas of upward leakage. Dissolution of gypsum or anhydrite and halite</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4152001','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4152001"><span>Inner ear tissue preservation by rapid <span class="hlt">freezing</span>: Improving fixation by high-pressure <span class="hlt">freezing</span> and hybrid methods</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bullen, A.; Taylor, R.R.; Kachar, B.; Moores, C.; Fleck, R.A.; Forge, A.</p> <p>2014-01-01</p> <p>In the preservation of tissues in as ‘close to life’ state as possible, rapid <span class="hlt">freeze</span> fixation has many benefits over conventional chemical fixation. One technique by which rapid <span class="hlt">freeze</span>-fixation can be achieved, high pressure <span class="hlt">freezing</span> (HPF), has been shown to enable ice crystal artefact-free <span class="hlt">freezing</span> and tissue preservation to greater depths (more than 40 μm) than other quick-<span class="hlt">freezing</span> methods. Despite increasingly becoming routine in electron microscopy, the use of HPF for the fixation of inner ear tissue has been limited. Assessment of the quality of preservation showed routine HPF techniques were suitable for preparation of inner ear tissues in a variety of species. Good preservation throughout the depth of sensory epithelia was achievable. Comparison to chemically fixed tissue indicated that fresh frozen preparations exhibited overall superior structural preservation of cells. However, HPF fixation caused characteristic artefacts in stereocilia that suggested poor quality <span class="hlt">freezing</span> of the actin bundles. The hybrid technique of pre-fixation and high pressure <span class="hlt">freezing</span> was shown to produce cellular preservation throughout the tissue, similar to that seen in HPF alone. Pre-fixation HPF produced consistent high quality preservation of stereociliary actin bundles. Optimising the preparation of samples with minimal artefact formation allows analysis of the links between ultrastructure and function in inner ear tissues. PMID:25016142</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27757990','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27757990"><span><span class="hlt">Freeze</span>-dried spermatozoa: A future tool?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Olaciregui, M; Gil, L</p> <p>2017-04-01</p> <p>Cryopreservation has been routinely used to preserve sperm of human and different animal species. However, frozen sperm storage for a long time brings many inconveniences because of liquid nitrogen. Many attempts have been made to overcome the disadvantages of the current cryopreservation method. <span class="hlt">Freeze</span>-drying has been proposed as alternative method for sperm preservation to achieve the ability to store sperm doses indefinitely at ambient temperature or in ordinary refrigerators. At present, it has been reported successfully sperm <span class="hlt">freeze</span>-drying on many animal species including canine and feline. It is well known that during <span class="hlt">freeze</span>-drying process, sperm DNA could be damaged, but if suitable protection is provided, the sperm nucleus could preserve the ability to activate the oocyte and embryos could be generated by intracytoplasmic sperm injection (ICSI). Many factors influence the <span class="hlt">freeze</span>-drying efficacy, so current researches have been conducted to find strategies to control these factors to maintain the sperm DNA integrity. This review describes the latest method of sperm <span class="hlt">freeze</span>-drying for practical application in preserving and transporting genetic resources. In addition, the approaches to improve the efficiency of the technique were studied. We demonstrated that the DNA integrity of <span class="hlt">freeze</span>-dried dog sperm is affected by the composition of the <span class="hlt">freeze</span>-drying solution as well as the temperature and period of storage. Further studies are necessary to refine <span class="hlt">freeze</span>-drying protocol in order to protect the DNA and maintain the sperm functionality and obtain offspring from <span class="hlt">freeze</span>-dried sperm. © 2016 Blackwell Verlag GmbH.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001EPJAP..16..231C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001EPJAP..16..231C"><span>Numerical simulation of the interaction of biological cells with an ice front during <span class="hlt">freezing</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carin, M.; Jaeger, M.</p> <p>2001-12-01</p> <p>The goal of this study is a better understanding of the interaction between cells and a solidification front during a cryopreservation process. This technique of <span class="hlt">freezing</span> is commonly used to conserve biological material for long periods at low temperatures. However the biophysical mechanisms of cell injuries during <span class="hlt">freezing</span> are difficult to understand because a cell is a very sophisticated microstructure interacting with its environment. We have developed a finite element model to simulate the response of cells to an advancing solidification front. A special front-tracking technique is used to compute the motion of the cell membrane and the ice front during <span class="hlt">freezing</span>. The model solves the conductive heat transfer equation and the diffusion equation of a solute on a domain containing three phases: one or more cells, the extra-cellular solution and the growing ice. This solid phase growing from a binary salt solution rejects the solute in the liquid phase and increases the solute <span class="hlt">gradient</span> around the cell. This induces the shrinkage of the cell. The model is used to simulate the engulfment of one cell modelling a red blood cell by an advancing solidification front initially planar or not is computed. We compare the incorporation of a cell with that of a solid particle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28792641','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28792641"><span><span class="hlt">Vertical</span> <span class="hlt">gradients</span> in species richness and community composition across the twilight zone in the North Pacific Subtropical Gyre.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sommer, Stephanie A; Van Woudenberg, Lauren; Lenz, Petra H; Cepeda, Georgina; Goetze, Erica</p> <p>2017-11-01</p> <p>Although metazoan animals in the mesopelagic zone play critical roles in deep pelagic food webs and in the attenuation of carbon in midwaters, the diversity of these assemblages is not fully known. A metabarcoding survey of mesozooplankton diversity across the epipelagic, mesopelagic and upper bathypelagic zones (0-1500 m) in the North Pacific Subtropical Gyre revealed far higher estimates of species richness than expected given prior morphology-based studies in the region (4,024 OTUs, 10-fold increase), despite conservative bioinformatic processing. Operational taxonomic unit (OTU) richness of the full assemblage peaked at lower epipelagic-upper mesopelagic depths (100-300 m), with slight shoaling of maximal richness at night due to diel <span class="hlt">vertical</span> migration, in contrast to expectations of a deep mesopelagic diversity maximum as reported for several plankton groups in early systematic and zoogeographic studies. Four distinct depth-stratified species assemblages were identified, with faunal transitions occurring at 100 m, 300 m and 500 m. Highest diversity occurred in the smallest zooplankton size fractions (0.2-0.5 mm), which had significantly lower % OTUs classified due to poor representation in reference databases, suggesting a deep reservoir of poorly understood diversity in the smallest metazoan animals. A diverse meroplankton assemblage also was detected (350 OTUs), including larvae of both shallow and deep living benthic species. Our results provide some of the first insights into the hidden diversity present in zooplankton assemblages in midwaters, and a molecular reappraisal of <span class="hlt">vertical</span> <span class="hlt">gradients</span> in species richness, depth distributions and community composition for the full zooplankton assemblage across the epipelagic, mesopelagic and upper bathypelagic zones. © 2017 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=271958','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=271958"><span><span class="hlt">Freeze</span> Tolerance of Nine Zoysiagrass Cultivars Using Natural Cold Acclimation and <span class="hlt">Freeze</span> Chambers</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Winter hardiness of zoysiagrass (Zoysia spp.) cultivars is an important attribute throughout the biogeographical transition zone, thus the inability to withstand <span class="hlt">freezing</span> temperatures may limit the use of these cultivars. The objective of this research was to determine the <span class="hlt">freeze</span> tolerance (LT50) of...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22130817-metallicity-gradients-through-disk-instability-simple-model-milky-way-boxy-bulge','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22130817-metallicity-gradients-through-disk-instability-simple-model-milky-way-boxy-bulge"><span>METALLICITY <span class="hlt">GRADIENTS</span> THROUGH DISK INSTABILITY: A SIMPLE MODEL FOR THE MILKY WAY'S BOXY BULGE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Martinez-Valpuesta, Inma; Gerhard, Ortwin, E-mail: imv@mpe.mpg.de, E-mail: gerhard@mpe.mpg.de</p> <p>2013-03-20</p> <p>Observations show a clear <span class="hlt">vertical</span> metallicity <span class="hlt">gradient</span> in the Galactic bulge, which is often taken as a signature of dissipative processes in the formation of a classical bulge. Various evidence shows, however, that the Milky Way is a barred galaxy with a boxy bulge representing the inner three-dimensional part of the bar. Here we show with a secular evolution N-body model that a boxy bulge formed through bar and buckling instabilities can show <span class="hlt">vertical</span> metallicity <span class="hlt">gradients</span> similar to the observed <span class="hlt">gradient</span> if the initial axisymmetric disk had a comparable radial metallicity <span class="hlt">gradient</span>. In this framework, the range of metallicities inmore » bulge fields constrains the chemical structure of the Galactic disk at early times before bar formation. Our secular evolution model was previously shown to reproduce inner Galaxy star counts and we show here that it also has cylindrical rotation. We use it to predict a full mean metallicity map across the Galactic bulge from a simple metallicity model for the initial disk. This map shows a general outward <span class="hlt">gradient</span> on the sky as well as longitudinal perspective asymmetries. We also briefly comment on interpreting metallicity <span class="hlt">gradient</span> observations in external boxy bulges.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4692431','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4692431"><span>Tandem High-pressure <span class="hlt">Freezing</span> and Quick <span class="hlt">Freeze</span> Substitution of Plant Tissues for Transmission Electron Microscopy</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bobik, Krzysztof; Dunlap, John R.; Burch-Smith, Tessa M.</p> <p>2014-01-01</p> <p>Since the 1940s transmission electron microscopy (TEM) has been providing biologists with ultra-high resolution images of biological materials. Yet, because of laborious and time-consuming protocols that also demand experience in preparation of artifact-free samples, TEM is not considered a user-friendly technique. Traditional sample preparation for TEM used chemical fixatives to preserve cellular structures. High-pressure <span class="hlt">freezing</span> is the cryofixation of biological samples under high pressures to produce very fast cooling rates, thereby restricting ice formation, which is detrimental to the integrity of cellular ultrastructure. High-pressure <span class="hlt">freezing</span> and <span class="hlt">freeze</span> substitution are currently the methods of choice for producing the highest quality morphology in resin sections for TEM. These methods minimize the artifacts normally associated with conventional processing for TEM of thin sections. After cryofixation the frozen water in the sample is replaced with liquid organic solvent at low temperatures, a process called <span class="hlt">freeze</span> substitution. <span class="hlt">Freeze</span> substitution is typically carried out over several days in dedicated, costly equipment. A recent innovation allows the process to be completed in three hours, instead of the usual two days. This is typically followed by several more days of sample preparation that includes infiltration and embedding in epoxy resins before sectioning. Here we present a protocol combining high-pressure <span class="hlt">freezing</span> and quick <span class="hlt">freeze</span> substitution that enables plant sample fixation to be accomplished within hours. The protocol can readily be adapted for working with other tissues or organisms. Plant tissues are of special concern because of the presence of aerated spaces and water-filled vacuoles that impede ice-free <span class="hlt">freezing</span> of water. In addition, the process of chemical fixation is especially long in plants due to cell walls impeding the penetration of the chemicals to deep within the tissues. Plant tissues are therefore particularly challenging, but</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997JApMe..36..155C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997JApMe..36..155C"><span>Spray Irrigation Effects on Surface-Layer Stability in an Experimental Citrus Orchard during Winter <span class="hlt">Freezes</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cooper, Harry J.; Smith, Eric A.; Martsolf, J. David</p> <p>1997-02-01</p> <p>Observations taken by two surface radiation and energy budget stations deployed in the University of Florida/Institute for Food and Agricultural Service experimental citrus orchard in Gainesville, Florida, have been analyzed to identify the effects of sprayer irrigation on thermal stability and circulation processes within the orchard during three 1992 winter <span class="hlt">freeze</span> episodes. Lapse rates of temperature observed from a micrometeorological tower near the center of the orchard were also recorded during periods of irrigation for incorporation into the analysis. Comparisons of the near-surface temperature lapse rates observed with the two energy budget stations show consistency between the two sites and with the tower-based lapse rates taken over a <span class="hlt">vertical</span> layer from 1.5 to 15 m above ground level. A theoretical framework was developed that demonstrates that turbulent-scale processes originating within the canopy, driven by latent heat release associated with condensation and <span class="hlt">freezing</span> processes from water vapor and liquid water released from sprayer nozzles, can destabilize lapse rates and promote warm air mixing above the orchard canopy. The orchard data were then analyzed in the context of the theory for evidence of local overturning and displacement of surface-layer air, with warmer air from aloft driven by locally buoyant plumes generated by water vapor injected into the orchard during the irrigation periods. It was found that surface-layer lapse rates were lower during irrigation periods than under similar conditions when irrigation was not occurring, indicating a greater degree of <span class="hlt">vertical</span> mixing of surface-layer air with air from above treetops, as a result of local convective overturning induced by the condensation heating of water vapor released at the nozzles of the sprinklers. This provides an additional explanation to the well-accepted heat of fusion release effect, of how undertree irrigation of a citrus orchard during a <span class="hlt">freeze</span> period helps protect crops</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.5707W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.5707W"><span>Immersion <span class="hlt">freezing</span> by SnomaxTM particles: Comparison of results from different instruments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wex, Heike; Stratmann, Frank; Rösch, Michael; Niedermeier, Dennis; Nilius, Björn; Möhler, Ottmar; Mitra, Subir K.; Koop, Thomas; Jantsch, Evelyn; Hiranuma, Naruki; Diehl, Karoline; Curtius, Joachim; Budke, Carsten; Boose, Yvonne; Augustin, Stefanie</p> <p>2014-05-01</p> <p>Within the DFG funded research unit INUIT (Ice Nucleation research UnIT, FOR 1525), an effort was made to compare results on immersion <span class="hlt">freezing</span> from a suite of different instruments. Besides mineral dusts, SnomaxTM was picked as one of the substances that were examined by all participating groups. Here, the comparison of the results for SnomaxTM is presented. Every participating group used SnomaxTM from the same batch and, as far as possible, the same particle generation set-up. Instruments participating in the comparison were, in alphabetical order, an acoustic levitator (Diehl et al., 2009), AIDA (Connolly et al., 2009), BINARY (Budke et al., 2013), FINCH (Bundke et al., 2008), LACIS (Hartmann et al., 2011), PINC (Chou et al., 2011) and the Mainz <span class="hlt">vertical</span> windtunnel (Diehl et al., 2011). Some of the instruments examined droplets directly produced from SnomaxTM suspensions, where the suspensions could have a wide range of concentrations. Other instruments used size segregated particles which were generated via atomization from a SnomaxTM suspension and subsequent drying, followed by size selection with a DMA (Differential Mobility Analyzer). These particles were then activated to droplets and cooled subsequently. For these, the number of ice nucleation active protein complexes present in the droplets depended on the original particle size (for details see e.g. Hartmann et al., 2013). Also, the different measurements spanned a range of different time scales. The shortest residence time of roughly 1 second was used for LACIS measurements, and the longest one was about 6 seconds used in the BINARY setup with a cooling rate of 1 K/min. All data were evaluated using two different approaches: 1) a time dependent approach following Classical Nucleation Theory which included the use of a contact angle distribution (see Niedermeier et al., 2014); 2) a singular approach using an active site density per mass (see Vali, 1971, Murray et al., 2012). Both approaches were found</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title9-vol2/pdf/CFR-2010-title9-vol2-sec590-534.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title9-vol2/pdf/CFR-2010-title9-vol2-sec590-534.pdf"><span>9 CFR 590.534 - <span class="hlt">Freezing</span> facilities.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false <span class="hlt">Freezing</span> facilities. 590.534 Section 590.534 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE EGG..., and Facility Requirements § 590.534 <span class="hlt">Freezing</span> facilities. (a) <span class="hlt">Freezing</span> rooms, either on or off the...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title9-vol2/pdf/CFR-2010-title9-vol2-sec590-536.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title9-vol2/pdf/CFR-2010-title9-vol2-sec590-536.pdf"><span>9 CFR 590.536 - <span class="hlt">Freezing</span> operations.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false <span class="hlt">Freezing</span> operations. 590.536 Section 590.536 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE EGG..., and Facility Requirements § 590.536 <span class="hlt">Freezing</span> operations. (a) <span class="hlt">Freezing</span> rooms shall be kept clean and...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title3-vol1/pdf/CFR-2010-title3-vol1-other-id194.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title3-vol1/pdf/CFR-2010-title3-vol1-other-id194.pdf"><span>3 CFR - Pay <span class="hlt">Freeze</span></span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... 3 The President 1 2010-01-01 2010-01-01 false Pay <span class="hlt">Freeze</span> Presidential Documents Other Presidential Documents Memorandum of January 21, 2009 Pay <span class="hlt">Freeze</span> Memorandum for the Assistant to the President and Chief... the White House staff forgo pay increases until further notice. Accordingly, as a signal of our shared...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26172588','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26172588"><span>Soil respiration and carbon loss relationship with temperature and land use conversion in <span class="hlt">freeze</span>-thaw agricultural area.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ouyang, Wei; Lai, Xuehui; Li, Xia; Liu, Heying; Lin, Chunye; Hao, Fanghua</p> <p>2015-11-15</p> <p>Soil respiration (Rs) was hypothesized to have a special response pattern to soil temperature and land use conversion in the <span class="hlt">freeze</span>-thaw area. The Rs differences of eight types of land use conversions during agricultural development were observed and the impacts of Rs on soil organic carbon (SOC) loss were assessed. The land use conversions during last three decades were categorized into eight types, and the 141 SOC sampling sites were grouped by conversion type. The typical soil sampling sites were subsequently selected for monitoring of soil temperature and Rs of each land use conversion types. The Rs correlations with temperature at difference depths and different conversion types were identified with statistical analysis. The empirical mean error model and the biophysical theoretical model with Arrhenius equation about the Rs sensitivity to temperature were both analyzed and shared the similar patterns. The temperature dependence of soil respiration (Q10) analysis further demonstrated that the averaged value of eight types of land use in this <span class="hlt">freeze</span>-thaw agricultural area ranged from 1.15 to 1.73, which was lower than the other cold areas. The temperature dependence analysis demonstrated that the Rs in the top layer of natural land covers was more sensitive to temperature and experienced a large <span class="hlt">vertical</span> difference. The natural land covers exhibited smaller Rs and the farmlands had the bigger value due to tillage practices. The positive relationships between SOC loss and Rs were identified, which demonstrated that Rs was the key chain for SOC loss during land use conversion. The spatial-<span class="hlt">vertical</span> distributions of SOC concentration with the 1.5-km grid sampling showed that the more SOC loss in the farmland, which was coincided with the higher Rs in farmlands. The analysis of Rs dynamics provided an innovative explanation for SOC loss in the <span class="hlt">freeze</span>-thaw agricultural area. The analysis of Rs dynamics provided an innovative explanation for SOC loss in the <span class="hlt">freeze</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25016142','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25016142"><span>Inner ear tissue preservation by rapid <span class="hlt">freezing</span>: improving fixation by high-pressure <span class="hlt">freezing</span> and hybrid methods.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bullen, A; Taylor, R R; Kachar, B; Moores, C; Fleck, R A; Forge, A</p> <p>2014-09-01</p> <p>In the preservation of tissues in as 'close to life' state as possible, rapid <span class="hlt">freeze</span> fixation has many benefits over conventional chemical fixation. One technique by which rapid <span class="hlt">freeze</span>-fixation can be achieved, high pressure <span class="hlt">freezing</span> (HPF), has been shown to enable ice crystal artefact-free <span class="hlt">freezing</span> and tissue preservation to greater depths (more than 40 μm) than other quick-<span class="hlt">freezing</span> methods. Despite increasingly becoming routine in electron microscopy, the use of HPF for the fixation of inner ear tissue has been limited. Assessment of the quality of preservation showed routine HPF techniques were suitable for preparation of inner ear tissues in a variety of species. Good preservation throughout the depth of sensory epithelia was achievable. Comparison to chemically fixed tissue indicated that fresh frozen preparations exhibited overall superior structural preservation of cells. However, HPF fixation caused characteristic artefacts in stereocilia that suggested poor quality <span class="hlt">freezing</span> of the actin bundles. The hybrid technique of pre-fixation and high pressure <span class="hlt">freezing</span> was shown to produce cellular preservation throughout the tissue, similar to that seen in HPF alone. Pre-fixation HPF produced consistent high quality preservation of stereociliary actin bundles. Optimising the preparation of samples with minimal artefact formation allows analysis of the links between ultrastructure and function in inner ear tissues. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17779616','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17779616"><span>Core drilling through the ross ice shelf (antarctica) confirmed Basal <span class="hlt">freezing</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zotikov, I A; Zagorodnov, V S; Raikovsky, J V</p> <p>1980-03-28</p> <p>New techniques that have been used to obtain a continuous ice core through the whole 416-meter thickness of the Ross Ice Shelf at Camp J-9 have demonstrated that the bottom 6 meters of the ice shelf consists of sea ice. The rate of basal <span class="hlt">freezing</span> that is forming this ice is estimated by different methods to be 2 centimeters of ice per year. The sea ice is composed of large <span class="hlt">vertical</span> crystals, which form the waffle-like lower boundary of the shelf. A distinct alignment of the crystals throughout the sea ice layer suggests the presence of persistent long-term currents beneath the ice shelf.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21374626','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21374626"><span><span class="hlt">Freeze</span>-drying of nanosuspensions, 1: <span class="hlt">freezing</span> rate versus formulation design as critical factors to preserve the original particle size distribution.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Beirowski, Jakob; Inghelbrecht, Sabine; Arien, Albertina; Gieseler, Henning</p> <p>2011-05-01</p> <p>It has been recently reported in the literature that using a fast <span class="hlt">freezing</span> rate during <span class="hlt">freeze</span>-drying of drug nanosuspensions is beneficial to preserve the original particle size distribution. All <span class="hlt">freezing</span> rates studied were obtained by utilizing a custom-made apparatus and were then indirectly related to conventional vial <span class="hlt">freeze</span>-drying. However, a standard <span class="hlt">freeze</span>-dryer is only capable of achieving moderate <span class="hlt">freezing</span> rates in the shelf fluid circulation system. Therefore, it was the purpose of the present study to evaluate the possibility to establish a typical <span class="hlt">freezing</span> protocol applicable to a standard <span class="hlt">freeze</span>-drying unit in combination with an adequate choice of cryoprotective excipients and steric stabilizers to preserve the original particle size distribution. Six different drug nanosuspensions containing itraconazole as a drug model were studied using <span class="hlt">freeze</span>-thaw experiments and a full factorial design to reveal major factors for the stabilization of drug nanosuspensions and the corresponding interactions. In contrast to previous reports, the <span class="hlt">freezing</span> regime showed no significant influence on preserving the original particle size distribution, suggesting that the concentrations of both the steric stabilizer and the cryoprotective agent are optimized. Moreover, it could be pinpointed that the combined effect of steric stabilizer and cryoprotectant clearly contribute to nanoparticle stability. Copyright © 2010 Wiley-Liss, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27804787','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27804787"><span>Pharmaceutical patent applications in <span class="hlt">freeze</span>-drying.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ekenlebie, Edmond; Einfalt, Tomaž; Karytinos, Arianna Irò; Ingham, Andrew</p> <p>2016-09-01</p> <p>Injectable products are often the formulation of choice for new therapeutics; however, formulation in liquids often enhances degradation through hydrolysis. Thus, <span class="hlt">freeze</span>-drying (lyophilization) is regularly used in pharmaceutical manufacture to reduce water activity. Here we examine its contribution to 'state of the art' and look at its future potential uses. A comprehensive search of patent databases was conducted to characterize the international patent landscape and trends in the use of <span class="hlt">freeze</span>-drying. A total of 914 disclosures related to <span class="hlt">freeze</span>-drying, lyophilization or drying of solid systems in pressures and temperatures equivalent to those of <span class="hlt">freeze</span>-drying were considered over the period of 1992-2014. Current applications of sublimation technology were contrasted across two periods those with patents due to expire (1992-1993) and those currently filed. The number of <span class="hlt">freeze</span>-drying technology patents has stabilized after initial activity across the biotechnology sector in 2011 and 2012. Alongside an increasing trend for patent submissions, <span class="hlt">freeze</span>-drying submissions have slowed since 2002 and is indicative of a level of maturity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26998343','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26998343"><span>Effects of various <span class="hlt">freezing</span> containers for vitrification <span class="hlt">freezing</span> on mouse oogenesis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kim, Ji Chul; Kim, Jae Myeoung; Seo, Byoung Boo</p> <p>2016-01-01</p> <p>In the present study, various <span class="hlt">freezing</span> containers were tested for mouse embryos of respective developmental stages; embryos were vitrified and then their survival rate and developmental rate were monitored. Mouse two cell, 8 cell, and blastula stage embryos underwent vitrification <span class="hlt">freezing</span>-thawing and then their recovery rate, survival rate, development rate, and hatching rate were investigated. EM-grid, OPS, and cryo-loop were utilized for vitrification <span class="hlt">freezing</span>-thawing of mouse embryos. It was found that recovery rate and survival rate were higher in the group of cryo-loop compared to those of EM-grid (p < 0.05). Embryonic development rate, two cell embryos to blastocyst, as well as hatching rate were higher in the control group compared to the EM-grid group and OPS group (p < 0.05), yet no difference was noted between the control group and cryo-loop group. Development rate and hatching rate of eight cell morulae and blastocysts were all lower in the treatment groups than the control group whilst hatching rate of blastocysts was higher in the control group compared to the groups of EM-grid and OPS (p < 0.05); although the cryo-loop group was shown to be slightly higher than other groups, it was not statistically significant. In the study, we investigate effects of <span class="hlt">freezing</span> containers on vitrified embryos of respective developmental stages; it was demonstrated that higher developmental rate was shown in more progressed (or developed) embryos with more blastomeres. There was however, no difference in embryonic development rate was shown amongst containers. Taken together, further additional studies are warranted with regards to 1) manipulation techniques of embryos for various vitrification <span class="hlt">freezing</span> containers and 2) preventive measures against contamination via liquid nitrogen.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000032226&hterms=Benzil&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DBenzil','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000032226&hterms=Benzil&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DBenzil"><span>Bulk Crystal Growth of Nonlinear Optical Organic Materials Using Inverted <span class="hlt">Vertical</span> <span class="hlt">Gradient</span> <span class="hlt">Freeze</span> Method</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Choi, J.; Cruz, Magda; Metzl, R.; Wang, W. S.; Aggarwal, M. D.; Penn, Benjamin G.; Frazier, Donald O.</p> <p>1998-01-01</p> <p>A new process for producing large bulk single crystals of benzil (C6H5COCOC6H5) is reported in this paper. Good quality crystals have been successfully grown using this approach to crystal growth. This method seems to be very promising for other thermally stable NLO organic materials also. The entire contents vycor crucible 1.5 inch in diameter and 2 inch deep was converted to single crystal. Purity of the starting growth material is also an important factor in the final quality of the grown crystals. The entire crystal can be very easily taken out of the crucible by simple maneuvering. Initial characterization of the grown crystals indicated that the crystals are as good as other crystals grown by conventional Bridgman Stockbarger technique.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28178320','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28178320"><span>Variations in the structural and functional diversity of zooplankton over <span class="hlt">vertical</span> and horizontal environmental <span class="hlt">gradients</span> en route to the Arctic Ocean through the Fram Strait.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gluchowska, Marta; Trudnowska, Emilia; Goszczko, Ilona; Kubiszyn, Anna Maria; Blachowiak-Samolyk, Katarzyna; Walczowski, Waldemar; Kwasniewski, Slawomir</p> <p>2017-01-01</p> <p>A multi-scale approach was used to evaluate which spatial <span class="hlt">gradient</span> of environmental variability is the most important in structuring zooplankton diversity in the West Spitsbergen Current (WSC). The WSC is the main conveyor of warm and biologically rich Atlantic water to the Arctic Ocean through the Fram Strait. The data set included 85 stratified <span class="hlt">vertical</span> zooplankton samples (obtained from depths up to 1000 metres) covering two latitudinal sections (76°30'N and 79°N) located across the multi-path WSC system. The results indicate that the most important environmental variables shaping the zooplankton structural and functional diversity and standing stock variability are those associated with depth, whereas variables acting in the horizontal dimension are of lesser importance. Multivariate analysis of the zooplankton assemblages, together with different univariate descriptors of zooplankton diversity, clearly illustrated the segregation of zooplankton taxa in the <span class="hlt">vertical</span> plane. The epipelagic zone (upper 200 m) hosted plentiful, Oithona similis-dominated assemblages with a high proportion of filter-feeding zooplankton. Although total zooplankton abundance declined in the mesopelagic zone (200-1000 m), zooplankton assemblages in that zone were more diverse and more evenly distributed, with high contributions from both herbivorous and carnivorous taxa. The <span class="hlt">vertical</span> distribution of integrated biomass (mg DW m-2) indicated that the total zooplankton biomass in the epipelagic and mesopelagic zones was comparable. Environmental <span class="hlt">gradients</span> acting in the horizontal plane, such as the ones associated with different ice cover and timing of the spring bloom, were reflected in the latitudinal variability in protist community structure and probably caused differences in succession in the zooplankton community. High abundances of Calanus finmarchicus in the WSC core branch suggest the existence of mechanisms advantageous for higher productivity or/and responsible for physical</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24057382','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24057382"><span>High-pressure <span class="hlt">freezing</span> and <span class="hlt">freeze</span> substitution of Arabidopsis for electron microscopy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Austin, Jotham R</p> <p>2014-01-01</p> <p>The objectives of electron microscopy ultrastructural studies are to examine cellular architecture and relate the cell's structural machinery to dynamic functional roles. This aspiration is difficult to achieve if specimens have not been adequately preserved in a "living state"; hence specimen preparation is of the utmost importance for the success of any electron micrographic study. High-pressure <span class="hlt">freezing</span> (HPF)/<span class="hlt">freeze</span> substitution (FS) has long been recognized as the primer technique for the preservation of ultrastructure in biological samples. In most cases a basic HPF/<span class="hlt">freeze</span> substitution protocol is sufficient to obtain superior ultrastructural preservation and structural contrast, which allows one to use more advanced microscopy techniques such as 3D electron tomography. However, for plant tissues, which have a thick cell wall, large water-filled vacuoles, and air spaces (all of which are detrimental to cryopreservation), these basic HPF/FS protocols often yield undesirable results. In particular, ice crystal artifacts and the staining of membrane systems are often poorly or negatively stained, which make 3D segmentation of a tomogram difficult. To overcome these problems, various aspects of the HPF/FS protocol can be altered, including the cryo-filler(s) used, <span class="hlt">freeze</span> substitution cocktail, and the resin infiltration process. This chapter will describe these modifications for the preparation of plant tissues for routine electron microscopic studies, immunocytochemistry, and 3D tomographic electron imaging.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27211670','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27211670"><span>Effects of industrial pre-<span class="hlt">freezing</span> processing and <span class="hlt">freezing</span> handling on glucosinolates and antioxidant attributes in broccoli florets.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cai, Congxi; Miao, Huiying; Qian, Hongmei; Yao, Leishuan; Wang, Bingliang; Wang, Qiaomei</p> <p>2016-11-01</p> <p>The effects of industrial pre-<span class="hlt">freezing</span> processing and <span class="hlt">freezing</span> handling on the contents of glucosinolates and antioxidants (vitamin C, polyphenols, carotenoid and chlorophyll), as well as the antioxidant capacity in broccoli (Brassica oleracea L. var. italica) florets were investigated in the present study. Our results showed that the glucosinolate accumulations were significantly decreased after pre-<span class="hlt">freezing</span> processing, whereas elevated levels of phenols, carotenoids, chlorophyll, and also antioxidant capacity were observed in frozen broccoli florets. The contents of vitamin C remained constant during above mentioned processing. In conclusion, the current industrial <span class="hlt">freezing</span> processing method is a good practice for the preservation of main antioxidant nutrients in broccoli florets, although some improvements in pre-<span class="hlt">freezing</span> processing, such as steam blanching and ice-water cooling, are needed to attenuate the decrease in glucosinolate content. Copyright © 2016 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JOM....65f.720P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JOM....65f.720P"><span>Biomimetic Materials by <span class="hlt">Freeze</span> Casting</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Porter, Michael M.; Mckittrick, Joanna; Meyers, Marc A.</p> <p>2013-06-01</p> <p>Natural materials, such as bone and abalone nacre, exhibit exceptional mechanical properties, a product of their intricate microstructural organization. <span class="hlt">Freeze</span> casting is a relatively simple, inexpensive, and adaptable materials processing method to form porous ceramic scaffolds with controllable microstructural features. After infiltration of a second polymeric phase, hybrid ceramic-polymer composites can be fabricated that closely resemble the architecture and mechanical performance of natural bone and nacre. Inspired by the narwhal tusk, magnetic fields applied during <span class="hlt">freeze</span> casting can be used to further control architectural alignment, resulting in <span class="hlt">freeze</span>-cast materials with enhanced mechanical properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27..824B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27..824B"><span><span class="hlt">Vertical</span> Mixing In Western Lake Constance Due To Long Internal Waves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Boehrer, B.</p> <p></p> <p>Current profiles in the pelagic waters of western Lake Constance have been broken up into modes of the internal wave equation [1,2]. All current profiles can be well represented by a combination of the first and second mode wave. The temporal vari- ation of the modal composition with the interaction of the first and second mode im- plies current shear at varying depths. From current and density profiles, the <span class="hlt">gradient</span> Richardson number can be evaluated in its spatial and temporal pattern with occa- tional occurence of supercritical values at all depths, also in the deep hypolimnion. An empiric connection between <span class="hlt">gradient</span> Richardson number and diapycnical mixing [3] is applied to yield a profile of <span class="hlt">vertical</span> transport coefficients, which can be com- pared with transport coefficients from <span class="hlt">gradient</span> flux calculations of temperature and electrical conductivity profiles [4]. [1] B. Boehrer, J. Ilmberger and K.O. Münnich (2000): <span class="hlt">Vertical</span> Structure of Current in Western Lake Constance, JGR-Oceans, 105 (12), 28823-28835 [2] B. Boehrer (2000): Modal Response of a Deep Stratified Lake: Western Lake Con- stance, JGR-Oceans, 105 (12), 28837-28845 [3] H. Peeters, M.C. Gregg and J.M. Toole (1988): On the parameterization of equa- torial turbulence, JGR, 93, 1199-1218 [4] G. Heinz, J. Ilmberger and M. Schimmele (1990): <span class="hlt">Vertical</span> Mixing in Überlinger See, western part of Lake Constance, Aquat. Sci., 52(3), 256-268</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950063666&hterms=1041&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2526%25231041','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950063666&hterms=1041&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2526%25231041"><span>Atmospheric <span class="hlt">gradients</span> from very long baseline interferometry observations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Macmillan, D. S.</p> <p>1995-01-01</p> <p>Azimuthal asymmetries in the atmospheric refractive index can lead to errors in estimated <span class="hlt">vertical</span> and horizontal station coordinates. Daily average <span class="hlt">gradient</span> effects can be as large as 50 mm of delay at a 7 deg elevation. To model <span class="hlt">gradients</span>, the constrained estimation of <span class="hlt">gradient</span> paramters was added to the standard VLBI solution procedure. Here the analysis of two sets of data is summarized: the set of all geodetic VLBI experiments from 1990-1993 and a series of 12 state-of-the-art R&D experiments run on consecutive days in January 1994. In both cases, when the <span class="hlt">gradient</span> parameters are estimated, the overall fit of the geodetic solution is improved at greater than the 99% confidence level. Repeatabilities of baseline lengths ranging up to 11,000 km are improved by 1 to 8 mm in a root-sum-square sense. This varies from about 20% to 40% of the total baseline length scatter without <span class="hlt">gradient</span> modeling for the 1990-1993 series and 40% to 50% for the January series. <span class="hlt">Gradients</span> estimated independently for each day as a piecewise linear function are mostly continuous from day to day within their formal uncertainties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/23436','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/23436"><span><span class="hlt">Freeze</span> injury to southern pine seedlings</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>David B. South</p> <p>2006-01-01</p> <p><span class="hlt">Freeze</span> injury to roots and shoots of pines is affected by genotype and nursery practices. Local sources of shortleaf pine and Virginia pine that are grown in nurseries in USDA hardiness Zones 6 and 7a are relatively <span class="hlt">freeze</span> tolerant. However, loblolly pine, slash pine, and longleaf pine seedlings have been injured by a number of <span class="hlt">freeze</span> events (0 to 24 °F) in hardiness...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1034766','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1034766"><span>Air-Cooled Stack <span class="hlt">Freeze</span> Tolerance <span class="hlt">Freeze</span> Failure Modes and <span class="hlt">Freeze</span> Tolerance Strategies for GenDriveTM Material Handling Application Systems and Stacks Final Scientific Report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Hancock, David, W.</p> <p>2012-02-14</p> <p>Air-cooled stack technology offers the potential for a simpler system architecture (versus liquid-cooled) for applications below 4 kilowatts. The combined cooling and cathode air allows for a reduction in part count and hence a lower cost solution. However, efficient heat rejection challenges escalate as power and ambient temperature increase. For applications in ambient temperatures below <span class="hlt">freezing</span>, the air-cooled approach has additional challenges associated with not overcooling the fuel cell stack. The focus of this project was <span class="hlt">freeze</span> tolerance while maintaining all other stack and system requirements. Through this project, Plug Power advanced the state of the art in technology formore » air-cooled PEM fuel cell stacks and related GenDrive material handling application fuel cell systems. This was accomplished through a collaborative work plan to improve <span class="hlt">freeze</span> tolerance and mitigate <span class="hlt">freeze</span>-thaw effect failure modes within innovative material handling equipment fuel cell systems designed for use in freezer forklift applications. <span class="hlt">Freeze</span> tolerance remains an area where additional research and understanding can help fuel cells to become commercially viable. This project evaluated both stack level and system level solutions to improve fuel cell stack <span class="hlt">freeze</span> tolerance. At this time, the most cost effective solutions are at the system level. The <span class="hlt">freeze</span> mitigation strategies developed over the course of this project could be used to drive fuel cell commercialization. The fuel cell system studied in this project was Plug Power's commercially available GenDrive platform providing battery replacement for equipment in the material handling industry. The fuel cell stacks were Ballard's commercially available FCvelocity 9SSL (9SSL) liquid-cooled PEM fuel cell stack and FCvelocity 1020ACS (Mk1020) air-cooled PEM fuel cell stack.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27074589','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27074589"><span>The effect of undissolved air on isochoric <span class="hlt">freezing</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Perez, Pedro A; Preciado, Jessica; Carlson, Gary; DeLonzor, Russ; Rubinsky, Boris</p> <p>2016-06-01</p> <p>This study evaluates the effect of undissolved air on isochoric <span class="hlt">freezing</span> of aqueous solutions. Isochoric <span class="hlt">freezing</span> is concerned with <span class="hlt">freezing</span> in a constant volume thermodynamic system. A possible advantage of the process is that it substantially reduces the percentage of ice in the system at every subzero temperature, relative to atmospheric <span class="hlt">freezing</span>. At the pressures generated by isochoric <span class="hlt">freezing</span>, or high pressure isobaric <span class="hlt">freezing</span>, air cannot be considered an incompressible substance and the presence of undissolved air substantially increases the amount of ice that forms at any subfreezing temperature. This effect is measurable at air volumes as low as 1%. Therefore eliminating the undissolved air, or any separate gaseous phase, from the system is essential for retaining the properties of isochoric <span class="hlt">freezing</span>. Copyright © 2016. Published by Elsevier Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2987464','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2987464"><span>Inflorescences of alpine cushion plants <span class="hlt">freeze</span> autonomously and may survive subzero temperatures by supercooling</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hacker, Jürgen; Ladinig, Ursula; Wagner, Johanna; Neuner, Gilbert</p> <p>2011-01-01</p> <p><span class="hlt">Freezing</span> patterns in the high alpine cushion plants Saxifraga bryoides, Saxifraga caesia, Saxifraga moschata and Silene acaulis were studied by infrared thermography at three reproductive stages (bud, anthesis, fruit development). The single reproductive shoots of a cushion froze independently in all four species at every reproductive stage. Ice formation caused lethal damage to the respective inflorescence. After ice nucleation, which occurred mainly in the stalk or the base of the reproductive shoot, ice propagated throughout that entire shoot, but not into neighboring shoots. However, anatomical ice barriers within cushions were not detected. The naturally occurring temperature <span class="hlt">gradient</span> within the cushion appeared to interrupt ice propagation thermally. Consequently, every reproductive shoot needed an autonomous ice nucleation event to initiate <span class="hlt">freezing</span>. Ice nucleation was not only influenced by minimum temperatures but also by the duration of exposure. At moderate subzero exposure temperatures (−4.3 to −7.7 °C) the number of frozen inflorescences increased exponentially. Due to efficient supercooling, single reproductive shoots remained unfrozen down to −17.4 °C (cooling rate 6 K h−1). Hence, the observed <span class="hlt">freezing</span> pattern may be advantageous for frost survival of individual inflorescences and reproductive success of high alpine cushion plants, when during episodic summer frosts damage can be avoided by supercooling. PMID:21151351</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70016655','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70016655"><span>Denitrification in nitrate-contaminated groundwater: Occurrence in steep <span class="hlt">vertical</span> geochemical <span class="hlt">gradients</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Smith, R.L.; Howes, B.L.; Duff, J.H.</p> <p>1991-01-01</p> <p>A relatively narrow <span class="hlt">vertical</span> zone (5-6 m thick) of NO3- containing groundwater was identified using multilevel sampling devices in a sand and gravel aquifer on Cape Cod, MA, USA. The aquifer has been chronically contaminated by surface disposal of treated sewage 0.3 km upgradient from the study area. The NO3- zone was anoxic and contained high concentrations of N2O (16.5 ??M), suggesting that it was a zone of active denitrification. Denitrifying activity was confirmed with direct measurement using acetylene block incubations with aquifer core material; the peak rate was 2.4 nmol N reduced (g sed)-1 day-1. Concentrations of dissolved inorganic carbon and N2 were close to atmospheric equilibrium in uncontaminated groundwater, but were more than 2 times higher within the contaminant plume. Excess CO2 and N2 suggested in situ formation with a stoichiometry of C and N mineralized via denitrification of 0.8 (C/N). Denitrification within the aquifer resulted in an increase in the natural ??15N of NO3- (from +13.6 to +42.0%.) and the N2 produced, with an isotopic enrichment factor, ??{lunate}, of -13.9%.. <span class="hlt">Vertical</span> profiles of NH4+ and ??15N of NH4+ indicated that dissimilatory reduction of NO3- to NH4+ was also occurring but mass balance calculations indicated that denitrification was the predominant process. These results demonstrate that a combination approach using field mass balance, stable isotope analysis, and laboratory incubations yields useful insight as to the significance of denitrification in aquifer sediments and that closely spaced <span class="hlt">vertical</span> sampling is necessary to adequately quantify the processes controlling C and N transport and transformation within these environments. ?? 1991.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25428024','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25428024"><span><span class="hlt">Freeze</span>-drying of lactic acid bacteria.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fonseca, Fernanda; Cenard, Stéphanie; Passot, Stéphanie</p> <p>2015-01-01</p> <p>Lactic acid bacteria are of great importance for the food and biotechnology industry. They are widely used as starters for manufacturing food (e.g., yogurt, cheese, fermented meats, and vegetables) and probiotic products, as well as for green chemistry applications. <span class="hlt">Freeze</span>-drying or lyophilization is a convenient method for preservation of bacteria. By reducing water activity to values below 0.2, it allows long-term storage and low-cost distribution at suprazero temperatures, while minimizing losses in viability and functionality. Stabilization of bacteria via <span class="hlt">freeze</span>-drying starts with the addition of a protectant solution to the bacterial suspension. <span class="hlt">Freeze</span>-drying includes three steps, namely, (1) <span class="hlt">freezing</span> of the concentrated and protected cell suspension, (2) primary drying to remove ice by sublimation, and (3) secondary drying to remove unfrozen water by desorption. In this chapter we describe a method for <span class="hlt">freeze</span>-drying of lactic acid bacteria at a pilot scale, thus allowing control of the process parameters for maximal survival and functionality recovery.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23576906','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23576906"><span><span class="hlt">Freeze</span>-thaw durability of air-entrained concrete.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shang, Huai-Shuai; Yi, Ting-Hua</p> <p>2013-01-01</p> <p>One of the most damaging actions affecting concrete is the abrupt temperature change (<span class="hlt">freeze</span>-thaw cycles). The types of deterioration of concrete structures by cyclic <span class="hlt">freeze</span>-thaw can be largely classified into surface scaling (characterized by the weight loss) and internal crack growth (characterized by the loss of dynamic modulus of elasticity). The present study explored the durability of concrete made with air-entraining agent subjected to 0, 100, 200, 300, and 400 cycles of <span class="hlt">freeze</span>-thaw. The experimental study of C20, C25, C30, C40, and C50 air-entrained concrete specimens was completed according to "the test method of long-term and durability on ordinary concrete" GB/T 50082-2009. The dynamic modulus of elasticity and weight loss of specimens were measured after different cycles of <span class="hlt">freeze</span>-thaw. The influence of <span class="hlt">freeze</span>-thaw cycles on the relative dynamic modulus of elasticity and weight loss was analyzed. The findings showed that the dynamic modulus of elasticity and weight decreased as the <span class="hlt">freeze</span>-thaw cycles were repeated. They revealed that the C30, C40, and C50 air-entrained concrete was still durable after 300 cycles of <span class="hlt">freeze</span>-thaw according to the experimental results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoJI.212.1588V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoJI.212.1588V"><span>Spatial wavefield <span class="hlt">gradient</span>-based seismic wavefield separation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Van Renterghem, C.; Schmelzbach, C.; Sollberger, D.; Robertsson, J. OA</p> <p>2018-03-01</p> <p>Measurements of the horizontal and <span class="hlt">vertical</span> components of particle motion combined with estimates of the spatial <span class="hlt">gradients</span> of the seismic wavefield enable seismic data to be acquired and processed using single dedicated multicomponent stations (e.g. rotational sensors) and/or small receiver groups instead of large receiver arrays. Here, we present seismic wavefield decomposition techniques that use spatial wavefield <span class="hlt">gradient</span> data to separate land and ocean bottom data into their upgoing/downgoing and P/S constituents. Our method is based on the elastodynamic representation theorem with the derived filters requiring local measurements of the wavefield and its spatial <span class="hlt">gradients</span> only. We demonstrate with synthetic data and a land seismic field data example that combining translational measurements with spatial wavefield <span class="hlt">gradient</span> estimates allows separating seismic data recorded either at the Earth's free-surface or at the sea bottom into upgoing/downgoing and P/S wavefield constituents for typical incidence angle ranges of body waves. A key finding is that the filter application only requires knowledge of the elastic properties exactly at the recording locations and is valid for a wide elastic property range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26201132','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26201132"><span>Comparison of Cryopreserved Human Sperm between Ultra Rapid <span class="hlt">Freezing</span> and Slow Programmable <span class="hlt">Freezing</span>: Effect on Motility, Morphology and DNA Integrity.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tongdee, Pattama; Sukprasert, Matchuporn; Satirapod, Chonticha; Wongkularb, Anna; Choktanasiri, Wicham</p> <p>2015-05-01</p> <p>Cryopreservation of sperm is common methods to preserve male fertility. Sperm <span class="hlt">freezing</span>, suggest slow programmable <span class="hlt">freezing</span> caused lower change of sperm morphology than sperm <span class="hlt">freezing</span> in vapor of liquid nitrogen. Ultra rapid <span class="hlt">freezing</span> is easy to be worked on, less time, low cost and does not need high experience. To compare the effect on sperm motility, morphology and DNA integrity of post-thawed sperm after ultra rapid <span class="hlt">freezing</span> and slow programmable <span class="hlt">freezing</span> methods. Experimental study at laboratory of infertility unit, Department of Obstetrics and Gynecology, Faculty of Medicine Ramathibodi Hospital. Thirty-seven semen samples with normal semen analysis according to World Health Organization (WHO) 1999 [normal sperm volume ( 2 ml) and normal sperm concentration (≥ 20 x10(6)/ml) and sperm motility (≥ 50%)]. Semen samples were washed. Then each semen sample was divided into six cryovials. Two cryovials, 0.5 ml each, were cryopreserved by slow programmable <span class="hlt">freezing</span>. Four 0.25 ml containing cryovials, were cryopreserved by ultra rapidfreezing method. After cryopreservationfor 1 month, thawedprocess was carried out at room temperature. Main outcomes are sperm motility was determined by Computer-Assisted Semen Analysis (CASA), sperm morphology was determined by eosin-methylene blue staining and sperm DNA integrity was assessed by TUNEL assay. Sperm motility was reduced significantly by both methods, from 70.4 (9.0)% to 29.1 (12.3)% in slowprogrammable <span class="hlt">freezing</span> and to 19.7 (9.8)% in ultra rapid <span class="hlt">freezing</span> (p < 0.05). Sperm motility decreased significantly more by ultra rapid <span class="hlt">freezing</span> (p < 0.001). The percentage of normal sperm morphology and DNA integrity were also reduced significantly by both methods. However, no significant difference between the two methods was found (p > 0.05). Cryopreservation of human sperm for 1 month significantly decreased sperm motility, morphology and DNA integrity in both methods. However sperm motility was decreased more by ultra rapid</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=329140','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=329140"><span><span class="hlt">Freezing</span> tolerance of winter wheat as influenced by extended growth at low temperature and exposure to <span class="hlt">freeze</span>-thaw cycles</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>As the seasons progress, autumn-planted winter wheat plants (Triticum aestivum L.) first gain, then progressively lose <span class="hlt">freezing</span> tolerance. Exposing the plants to <span class="hlt">freeze</span>-thaw cycles of -3/3°C results in increased ability to tolerate subsequent <span class="hlt">freezing</span> to potentially damaging temperatures. This stu...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760018709','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760018709"><span>Mechanisms of deterioration of nutrients. [of <span class="hlt">freeze</span> dried foods</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Karel, M.; Flink, J. M.</p> <p>1976-01-01</p> <p>Methods which produce <span class="hlt">freeze</span> dried foods of improved quality were examined with emphasis on storage stability. Specific topics discussed include: microstructure of <span class="hlt">freeze</span> dried systems, investigation of structural changes in <span class="hlt">freeze</span> dried systems, artificial food matrices, osmotic preconcentration to yield improved quality <span class="hlt">freeze</span> dried fruits, and storage stability of osmotically preconcentrated <span class="hlt">freeze</span> dried fruits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=282428','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=282428"><span>Hatchling turtles survive <span class="hlt">freezing</span> during winter hibernation.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Storey, K B; Storey, J M; Brooks, S P; Churchill, T A; Brooks, R J</p> <p>1988-01-01</p> <p>Hatchlings of the painted turtle (Chrysemys picta marginata) are unique as the only reptile and highest vertebrate life form known to tolerate the natural <span class="hlt">freezing</span> of extracellular body fluids during winter hibernation. Turtles survived frequent exposures to temperatures as low as -6 degrees C to -8 degrees C in their shallow terrestrial nests over the 1987-1988 winter. Hatchlings collected in April 1988 had a mean supercooling point of -3.28 +/- 0.24 degrees C and survived 24 hr of <span class="hlt">freezing</span> at -4 degrees C with 53.4% +/- 1.98% of total body water as ice. Recovery appeared complete after 20 hr of thawing at 3 degrees C. However, <span class="hlt">freezing</span> at -10.9 degrees C, resulting in 67% ice, was lethal. A survey of possible cryoprotectants revealed a 2- to 3-fold increase in glucose content of liver and blood and a 3-fold increase in blood glycerol in response to <span class="hlt">freezing</span>. Although quantitatively low, these responses by spring turtles strongly indicate that these may be the winter-active cryoprotectants. The total amino acid pool of blood also increased 2.25-fold in <span class="hlt">freezing</span>-exposed turtles, and taurine accounted for 52% of the increase. Most organs accumulated high concentrations of lactate during <span class="hlt">freezing</span>, a response to the ischemic state imposed by extracellular <span class="hlt">freezing</span>. Changes in glycogen phosphorylase activity and levels of glucose 6-phosphate and fructose 2,6-bisphosphate were also consistent with a dependence on anaerobic glycolysis during <span class="hlt">freezing</span>. Studies of the molecular mechanisms of natural <span class="hlt">freeze</span> tolerance in these turtles may identify protective strategies that can be used in mammalian organ cryopreservation technology. PMID:3186730</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010PhDT........66P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010PhDT........66P"><span>The effect of water-soluble polymers on the microstructure and properties of <span class="hlt">freeze</span>-cast alumina ceramics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pekor, Christopher Michael</p> <p></p> <p>Porous ceramics can be divided into three separate classes based on their pore size: microporous ceramics with pores less than 2 nm, mesoporous ceramics with pores in the range of 2--50 nm and macroporous ceramics with pores that are greater than 50 nm. In particular, macroporous ceramics are used in a variety of applications such as refractories, molten metal filtration, diesel particulate filters, heterogeneous catalyst supports and biomedical scaffolds. <span class="hlt">Freeze</span> casting is a novel method used to create macroporous ceramics. In this method growing ice crystals act as a template for the pores and are solidified, often directionally, through a ceramic dispersion and removed from the green body through a <span class="hlt">freeze</span> drying procedure. This method has attracted some attention over the past few years due to its relative simplicity, flexibility and environmental friendliness. On top of this <span class="hlt">freeze</span> casting is capable of producing materials with high pore volume fractions, which is an advantage over processing by packing and necking of particles, where the pore volume fraction is typically less than 50%. Many of the basic processing variables that affect the <span class="hlt">freeze</span> cast microstructure, such as the temperature <span class="hlt">gradient</span>, interfacial velocity and solid loading of the dispersion have been well established in the literature. On the other hand, areas such as the effect of additives on the microstructure and mechanical properties have not been covered in great detail. In this study the concept of constitutional supercooling from basic solidification theory is used to explain the effects of two water-soluble polymers, polyethylene glycol and polyvinyl alcohol, on the microstructure of <span class="hlt">freeze</span> cast alumina ceramics. In addition, changes in the observed microstructure will be related to experimentally determined values of permeability and compressive strength.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT........17O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT........17O"><span><span class="hlt">Freezing</span>-induced deformation of biomaterials in cryomedicine</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ozcelikkale, Altug</p> <p></p> <p>Cryomedicine utilizes low temperature treatments of biological proteins, cells and tissues for cryopreservation, materials processing and cryotherapy. Lack of proper understanding of cryodamage that occurs during these applications remains to be the primary bottleneck for development of successful tissue cryopreservation and cryosurgery procedures. An engineering approach based on a view of biological systems as functional biomaterials can help identify, predict and control the primary cryodamage mechanisms by developing an understanding of underlying <span class="hlt">freezing</span>-induced biophysical processes. In particular, <span class="hlt">freezing</span> constitutes the main structural/mechanical origin of cryodamage and results in significant deformation of biomaterials at multiple length scales. Understanding of these <span class="hlt">freezing</span>-induced deformation processes and their effects on post-thaw biomaterial functionality is currently lacking but will be critical to engineer improved cryomedicine procedures. This dissertation addresses this problem by presenting three separate but related studies of <span class="hlt">freezing</span>-induced deformation at multiple length scales including nanometer-scale protein fibrils, single cells and whole tissues. A combination of rigorous experimentation and computational modeling is used to characterize post-thaw biomaterial structure and properties, predict biomaterial behavior and assess its post-thaw biological functionality. Firstly, <span class="hlt">freezing</span>-induced damage on hierarchical extracellular matrix structure of collagen is investigated at molecular, fibril and matrix levels. Results indicate to a specific kind of fibril damage due to <span class="hlt">freezing</span>-induced expansion of intrafibrillar fluid. This is followed by a study of <span class="hlt">freezing</span>-induced cell and tissue deformation coupled to osmotically driven cellular water transport. Computational and semi empirical modeling of these processes indicate that intracellular deformation of the cell during <span class="hlt">freezing</span> is heterogeneous and can interfere with cellular water</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ACP....17.9291S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ACP....17.9291S"><span>Horizontal and <span class="hlt">vertical</span> structure of reactive bromine events probed by bromine monoxide MAX-DOAS</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Simpson, William R.; Peterson, Peter K.; Frieß, Udo; Sihler, Holger; Lampel, Johannes; Platt, Ulrich; Moore, Chris; Pratt, Kerri; Shepson, Paul; Halfacre, John; Nghiem, Son V.</p> <p>2017-08-01</p> <p>Heterogeneous photochemistry converts bromide (Br-) to reactive bromine species (Br atoms and bromine monoxide, BrO) that dominate Arctic springtime chemistry. This phenomenon has many impacts such as boundary-layer ozone depletion, mercury oxidation and deposition, and modification of the fate of hydrocarbon species. To study environmental controls on reactive bromine events, the BRomine, Ozone, and Mercury EXperiment (BROMEX) was carried out from early March to mid-April 2012 near Barrow (Utqiaġvik), Alaska. We measured horizontal and <span class="hlt">vertical</span> <span class="hlt">gradients</span> in BrO with multiple-axis differential optical absorption spectroscopy (MAX-DOAS) instrumentation at three sites, two mobile and one fixed. During the campaign, a large crack in the sea ice (an open lead) formed pushing one instrument package ˜ 250 km downwind from Barrow (Utqiaġvik). Convection associated with the open lead converted the BrO <span class="hlt">vertical</span> structure from a surface-based event to a lofted event downwind of the lead influence. The column abundance of BrO downwind of the re-<span class="hlt">freezing</span> lead was comparable to upwind amounts, indicating direct reactions on frost flowers or open seawater was not a major reactive bromine source. When these three sites were separated by ˜ 30 km length scales of unbroken sea ice, the BrO amount and <span class="hlt">vertical</span> distributions were highly correlated for most of the time, indicating the horizontal length scales of BrO events were typically larger than ˜ 30 km in the absence of sea ice features. Although BrO amount and <span class="hlt">vertical</span> distribution were similar between sites most of the time, rapid changes in BrO with edges significantly smaller than this ˜ 30 km length scale episodically transported between the sites, indicating BrO events were large but with sharp edge contrasts. BrO was often found in shallow layers that recycled reactive bromine via heterogeneous reactions on snowpack. Episodically, these surface-based events propagated aloft when aerosol extinction was higher (> 0.1 km</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23897687','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23897687"><span>Molecular biology of <span class="hlt">freezing</span> tolerance.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Storey, Kenneth B; Storey, Janet M</p> <p>2013-07-01</p> <p>Winter survival for many kinds of animals involves <span class="hlt">freeze</span> tolerance, the ability to endure the conversion of about 65% of total body water into extracellular ice and the consequences that <span class="hlt">freezing</span> imposes including interruption of vital processes (e.g., heartbeat and breathing), cell shrinkage, elevated osmolality, anoxia/ischemia, and potential physical damage from ice. <span class="hlt">Freeze</span>-tolerant animals include various terrestrially hibernating amphibians and reptiles, many species of insects, and numerous other invertebrates inhabiting both terrestrial and intertidal environments. Well-known strategies of <span class="hlt">freezing</span> survival include accumulation of low molecular mass carbohydrate cryoprotectants (e.g., glycerol), use of ice nucleating agents/proteins for controlled triggering of ice growth and of antifreeze proteins that inhibit ice recrystallization, and good tolerance of anoxia and dehydration. The present article focuses on more recent advances in our knowledge of the genes and proteins that support <span class="hlt">freeze</span> tolerance and the metabolic regulatory mechanisms involved. Important roles have been identified for aquaporins and transmembrane channels that move cryoprotectants, heat shock proteins and other chaperones, antioxidant defenses, and metabolic rate depression. Genome and proteome screening has revealed many new potential targets that respond to <span class="hlt">freezing</span>, in particular implicating cytoskeleton remodeling as a necessary facet of low temperature and/or cell volume adaptation. Key regulatory mechanisms include reversible phosphorylation control of metabolic enzymes and microRNA control of gene transcript expression. These help to remodel metabolism to preserve core functions while suppressing energy expensive metabolic activities such as the cell cycle. All of these advances are providing a much more complete picture of life in the frozen state. © 2013 American Physiological Society.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21037616','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21037616"><span>Refractive-index measurements in <span class="hlt">freezing</span> sea-ice and sodium chloride brines.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Maykut, G A; Light, B</p> <p>1995-02-20</p> <p>Sea ice contains numerous pockets of brine and precipitated salts whose size and number distributions change dramatically with temperature. Theoretical treatment of scattering produced by these inclusions requires information on refractive-index differences among the brine, salts, and surrounding ice. Lacking specific data on refractive-index variations in the brine, we carried out laboratory measurements in <span class="hlt">freezing</span>-equilibrium solutions between -2 and -32 °C. Index values at 589 nm increased from 1.341 to 1.397 over this temperature range, corresponding to salinities of 35 and 240 parts per thousand (ppt). Spectral data were also taken at 50-nm intervals between 400 and 700 nm in nonequilibrium solutions with salinities ranging up to 300 ppt. Spectral <span class="hlt">gradients</span> increased slightly with salinity but showed no measurable dependence on temperature between +12 and -16 °C. The Lorentz-Lorenz equation, combined with data on density, molar refractivities, and brine composition, yielded temperature-dependent index predictions in excellent agreement with the experimental data. Similar index and density measurements in <span class="hlt">freezing</span> sodium chloride brines yielded values nearly identical to those in the sea-ice brines. The absence of mirabilite crystals in sodium chloride ice, however, will cause it to have higher transmissivity and lower reflectivity than sea ice above -22 °C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3618942','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3618942"><span><span class="hlt">Freeze</span>-Thaw Durability of Air-Entrained Concrete</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Shang, Huai-Shuai; Yi, Ting-Hua</p> <p>2013-01-01</p> <p>One of the most damaging actions affecting concrete is the abrupt temperature change (<span class="hlt">freeze</span>-thaw cycles). The types of deterioration of concrete structures by cyclic <span class="hlt">freeze</span>-thaw can be largely classified into surface scaling (characterized by the weight loss) and internal crack growth (characterized by the loss of dynamic modulus of elasticity). The present study explored the durability of concrete made with air-entraining agent subjected to 0, 100, 200, 300, and 400 cycles of <span class="hlt">freeze</span>-thaw. The experimental study of C20, C25, C30, C40, and C50 air-entrained concrete specimens was completed according to “the test method of long-term and durability on ordinary concrete” GB/T 50082-2009. The dynamic modulus of elasticity and weight loss of specimens were measured after different cycles of <span class="hlt">freeze</span>-thaw. The influence of <span class="hlt">freeze</span>-thaw cycles on the relative dynamic modulus of elasticity and weight loss was analyzed. The findings showed that the dynamic modulus of elasticity and weight decreased as the <span class="hlt">freeze</span>-thaw cycles were repeated. They revealed that the C30, C40, and C50 air-entrained concrete was still durable after 300 cycles of <span class="hlt">freeze</span>-thaw according to the experimental results. PMID:23576906</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2195283','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2195283"><span>Structurally Caused <span class="hlt">Freezing</span> Point Depression of Biological Tissues</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bloch, Rene; Walters, D. H.; Kuhn, Werner</p> <p>1963-01-01</p> <p>When investigating the <span class="hlt">freezing</span> behaviour (by thermal analysis) of the glycerol-extracted adductor muscle of Mytilus edulis it was observed that the temperature of ice formation in the muscular tissue was up to 1.5°C lower than the <span class="hlt">freezing</span> point of the embedding liquid, a 0.25 N KCl solution with pH = 4.9 with which the tissue had been equilibrated prior to the <span class="hlt">freezing</span> experiment. A smaller <span class="hlt">freezing</span> point depression was observed if the pH values of the embedding 0.25 N KCl solution were above or below pH = 4.9. Reasoning from results obtained previously in analogous experiments with artificial gels, the anomalous <span class="hlt">freezing</span> depression is explained by the impossibility of growing at the normal <span class="hlt">freezing</span> temperature regular macroscopic crystals inside the gel, due to the presence of the gel network. The <span class="hlt">freezing</span> temperature is here determined by the size of the microprisms penetrating the meshes of the network at the lowered <span class="hlt">freezing</span> temperature. This process leads finally to an ice block of more or less regular structure in which the filaments are embedded. Prerequisite for this hindrance of ideal ice growth is a sufficient tensile strength of the filamental network. The existence of structurally caused <span class="hlt">freezing</span> point depression in biological tissue is likely to invalidate many conclusions reported in the literature, in which hypertonicity was deduced from cryoscopic data. PMID:13971682</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16751565','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16751565"><span>Depth-related <span class="hlt">gradients</span> of viral activity in Lake Pavin.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Colombet, J; Sime-Ngando, T; Cauchie, H M; Fonty, G; Hoffmann, L; Demeure, G</p> <p>2006-06-01</p> <p>High-resolution <span class="hlt">vertical</span> sampling and determination of viral and prokaryotic parameters in a deep volcanic lake shows that in the absence of thermal stratification but within light, oxygen, and chlorophyll <span class="hlt">gradients</span>, host availability empirically is prevalent over the physical and chemical environments and favors lytic over lysogenic "viral life cycles."</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApPhL.110d1604C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApPhL.110d1604C"><span>Bulk water <span class="hlt">freezing</span> dynamics on superhydrophobic surfaces</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chavan, S.; Carpenter, J.; Nallapaneni, M.; Chen, J. Y.; Miljkovic, N.</p> <p>2017-01-01</p> <p>In this study, we elucidate the mechanisms governing the heat-transfer mediated, non-thermodynamic limited, <span class="hlt">freezing</span> delay on non-wetting surfaces for a variety of characteristic length scales, Lc (volume/surface area, 3 mm < Lc < 6 mm) using carefully designed <span class="hlt">freezing</span> experiments in a temperature-controlled, zero-humidity environment on thin water slabs. To probe the effect of surface wettability, we investigated the total time for room temperature water to completely <span class="hlt">freeze</span> into ice on superhydrophilic ( θaapp→ 0°), hydrophilic (0° < θa < 90°), hydrophobic (90° < θa < 125°), and superhydrophobic ( θaapp→ 180°) surfaces. Our results show that at macroscopic length scales, heat conduction through the bulk water/ice layer dominates the <span class="hlt">freezing</span> process when compared to heat conduction through the functional coatings or nanoscale gaps at the superhydrophobic substrate-water/ice interface. In order to verify our findings, and to determine when the surface structure thermal resistance approaches the water/ice resistance, we fabricated and tested the additional substrates coated with commercial superhydrophobic spray coatings, showing a monotonic increase in <span class="hlt">freezing</span> time with coating thickness. The added thermal resistance of thicker coatings was much larger than that of the nanoscale superhydrophobic features, which reduced the droplet heat transfer and increased the total <span class="hlt">freezing</span> time. Transient finite element method heat transfer simulations of the water slab <span class="hlt">freezing</span> process were performed to calculate the overall heat transfer coefficient at the substrate-water/ice interface during <span class="hlt">freezing</span>, and shown to be in the range of 1-2.5 kW/m2K for these experiments. The results shown here suggest that in order to exploit the heat-transfer mediated <span class="hlt">freezing</span> delay, thicker superhydrophobic coatings must be deposited on the surface, where the coating resistance is comparable to the bulk water/ice conduction resistance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170012505','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170012505"><span>A Theory of Immersion <span class="hlt">Freezing</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Barahona, Donifan</p> <p>2017-01-01</p> <p>Immersion <span class="hlt">freezing</span> is likely involved in the initiation of precipitation and determines to large extent the phase partitioning in convective clouds. Theoretical models commonly used to describe immersion <span class="hlt">freezing</span> in atmospheric models are based on the classical nucleation theory which however neglects important interactions near the immersed particle that may affect nucleation rates. This work introduces a new theory of immersion <span class="hlt">freezing</span> based on two premises. First, immersion ice nucleation is mediated by the modification of the properties of water near the particle-liquid interface, rather than by the geometry of the ice germ. Second, the same mechanism that leads to the decrease in the work of germ formation also decreases the mobility of water molecules near the immersed particle. These two premises allow establishing general thermodynamic constraints to the ice nucleation rate. Analysis of the new theory shows that active sites likely trigger ice nucleation, but they do not control the overall nucleation rate nor the probability of <span class="hlt">freezing</span>. It also suggests that materials with different ice nucleation efficiency may exhibit similar <span class="hlt">freezing</span> temperatures under similar conditions but differ in their sensitivity to particle surface area and cooling rate. Predicted nucleation rates show good agreement with observations for a diverse set of materials including dust, black carbon and bacterial ice nucleating particles. The application of the new theory within the NASA Global Earth System Model (GEOS-5) is also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050215212','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050215212"><span>Evaluation and Validation of the Messinger <span class="hlt">Freezing</span> Fraction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Anderson, David N.; Tsao, Jen-Ching</p> <p>2005-01-01</p> <p>One of the most important non-dimensional parameters used in ice-accretion modeling and scaling studies is the <span class="hlt">freezing</span> fraction defined by the heat-balance analysis of Messinger. For fifty years this parameter has been used to indicate how rapidly <span class="hlt">freezing</span> takes place when super-cooled water strikes a solid body. The value ranges from 0 (no <span class="hlt">freezing</span>) to 1 (water <span class="hlt">freezes</span> immediately on impact), and the magnitude has been shown to play a major role in determining the physical appearance of the accreted ice. Because of its importance to ice shape, this parameter and the physics underlying the expressions used to calculate it have been questioned from time to time. Until now, there has been no strong evidence either validating or casting doubt on the current expressions. This paper presents experimental measurements of the leading-edge thickness of a number of ice shapes for a variety of test conditions with nominal <span class="hlt">freezing</span> fractions from 0.3 to 1.0. From these thickness measurements, experimental <span class="hlt">freezing</span> fractions were calculated and compared with values found from the Messinger analysis as applied by Ruff. Within the experimental uncertainty of measuring the leading-edge thickness, agreement of the experimental and analytical <span class="hlt">freezing</span> fraction was very good. It is also shown that values of analytical <span class="hlt">freezing</span> fraction were entirely consistent with observed ice shapes at and near rime conditions: At an analytical <span class="hlt">freezing</span> fraction of unity, experimental ice shapes displayed the classic rime shape, while for conditions producing analytical <span class="hlt">freezing</span> fractions slightly lower than unity, glaze features started to appear.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22277841','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22277841"><span>Rapid <span class="hlt">freezing</span> without cooling equilibration in canine sperm.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kim, Suhee; Lee, Yongcheol; Yang, Honghyun; Kim, Yong-Jun</p> <p>2012-01-01</p> <p>The aim of this study was to develop a rapid method of canine semen <span class="hlt">freezing</span> without cooling equilibration using treatment with different cryoprotectant agents (CPAs) and <span class="hlt">freezing</span> in liquid nitrogen (LN(2)) vapor in a 0.5-mL straw via modifying vitrification. Ejaculates from eight beagle dogs were frozen with different CPAs (CPA-free, 5% glycerol, 5% ethylene glycol, and 10% ethylene glycol) and <span class="hlt">freezing</span> times (direct plunging into LN(2) or <span class="hlt">freezing</span> for 1, 2, 3, or 10 min in LN(2) vapor before plunging into LN(2)). Frozen-thawed sperm were evaluated for motility, viability, normal morphology, and plasma- and acrosome-membrane integrities. The 5% glycerol treatment resulted in improved sperm motility, plasma-membrane integrity and acrosome-membrane integrity (P<0.05). <span class="hlt">Freezing</span> in LN(2) vapor showed improved sperm motility, viability, and plasma membrane integrity (P<0.05), and <span class="hlt">freezing</span> for more than 2 min in LN(2) vapor increased acrosome-membrane integrity compared with direct plunging into LN(2) (P<0.05). The direct plunging into LN(2) showed no motile sperm. However, <span class="hlt">freezing</span> for more than 2 min in LN(2) vapor increased the total abnormalities compared to direct plunging into LN(2) (P<0.05). In conclusion, use of 5% glycerol and <span class="hlt">freezing</span> in LN(2) vapor were essential for the rapid <span class="hlt">freezing</span> of canine sperm without cooling equilibration. In particular, holding for 2 min in LN(2) vapor was sufficient to yield successful rapid <span class="hlt">freezing</span>. This rapid <span class="hlt">freezing</span> method is simple and effective in canine sperm and would be helpful to offer information for trial of vitrification in large volumes of canine sperm. Copyright © 2012 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DFD.A3002Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DFD.A3002Z"><span>Simulations of Flame Acceleration and DDT in Mixture Composition <span class="hlt">Gradients</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zheng, Weilin; Kaplan, Carolyn; Houim, Ryan; Oran, Elaine</p> <p>2017-11-01</p> <p>Unsteady, multidimensional, fully compressible numerical simulations of methane-air in an obstructed channel with spatial <span class="hlt">gradients</span> in equivalence ratios have been carried to determine the effects of the <span class="hlt">gradients</span> on flame acceleration and transition to detonation. Results for <span class="hlt">gradients</span> perpendicular to the propagation direction were considered here. A calibrated, optimized chemical-diffusive model that reproduces correct flame and detonation properties for methane-air over a range of equivalence ratios was derived from a combination of a genetic algorithm with a Nelder-Mead optimization scheme. Inhomogeneous mixtures of methane-air resulted in slower flame acceleration and longer distance to DDT. Detonations were more likely to decouple into a flame and a shock under sharper concentration <span class="hlt">gradients</span>. Detailed analyses of temperature and equivalence ratio illustrated that <span class="hlt">vertical</span> <span class="hlt">gradients</span> can greatly affect the formation of hot spots that initiate detonation by changing the strength of leading shock wave and local equivalence ratio near the base of obstacles. This work is supported by the Alpha Foundation (Grant No. AFC215-20).</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title9-vol2/pdf/CFR-2012-title9-vol2-sec590-536.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title9-vol2/pdf/CFR-2012-title9-vol2-sec590-536.pdf"><span>9 CFR 590.536 - <span class="hlt">Freezing</span> operations.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-01-01</p> <p>..., and Facility Requirements § 590.536 <span class="hlt">Freezing</span> operations. (a) <span class="hlt">Freezing</span> rooms shall be kept clean and... outside of liquid egg containers shall be clean and free from evidence of liquid egg. (e) Frozen egg...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title9-vol2/pdf/CFR-2014-title9-vol2-sec590-536.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title9-vol2/pdf/CFR-2014-title9-vol2-sec590-536.pdf"><span>9 CFR 590.536 - <span class="hlt">Freezing</span> operations.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-01-01</p> <p>..., and Facility Requirements § 590.536 <span class="hlt">Freezing</span> operations. (a) <span class="hlt">Freezing</span> rooms shall be kept clean and... outside of liquid egg containers shall be clean and free from evidence of liquid egg. (e) Frozen egg...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title9-vol2/pdf/CFR-2011-title9-vol2-sec590-536.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title9-vol2/pdf/CFR-2011-title9-vol2-sec590-536.pdf"><span>9 CFR 590.536 - <span class="hlt">Freezing</span> operations.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-01-01</p> <p>..., and Facility Requirements § 590.536 <span class="hlt">Freezing</span> operations. (a) <span class="hlt">Freezing</span> rooms shall be kept clean and... outside of liquid egg containers shall be clean and free from evidence of liquid egg. (e) Frozen egg...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title9-vol2/pdf/CFR-2013-title9-vol2-sec590-536.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title9-vol2/pdf/CFR-2013-title9-vol2-sec590-536.pdf"><span>9 CFR 590.536 - <span class="hlt">Freezing</span> operations.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-01-01</p> <p>..., and Facility Requirements § 590.536 <span class="hlt">Freezing</span> operations. (a) <span class="hlt">Freezing</span> rooms shall be kept clean and... outside of liquid egg containers shall be clean and free from evidence of liquid egg. (e) Frozen egg...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017OcSci..13..649S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017OcSci..13..649S"><span>A measurement system for <span class="hlt">vertical</span> seawater profiles close to the air-sea interface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sims, Richard P.; Schuster, Ute; Watson, Andrew J.; Yang, Ming Xi; Hopkins, Frances E.; Stephens, John; Bell, Thomas G.</p> <p>2017-09-01</p> <p>This paper describes a near-surface ocean profiler, which has been designed to precisely measure <span class="hlt">vertical</span> <span class="hlt">gradients</span> in the top 10 m of the ocean. Variations in the depth of seawater collection are minimized when using the profiler compared to conventional CTD/rosette deployments. The profiler consists of a remotely operated winch mounted on a tethered yet free-floating buoy, which is used to raise and lower a small frame housing sensors and inlet tubing. Seawater at the inlet depth is pumped back to the ship for analysis. The profiler can be used to make continuous <span class="hlt">vertical</span> profiles or to target a series of discrete depths. The profiler has been successfully deployed during wind speeds up to 10 m s-1 and significant wave heights up to 2 m. We demonstrate the potential of the profiler by presenting measured <span class="hlt">vertical</span> profiles of the trace gases carbon dioxide and dimethylsulfide. Trace gas measurements use an efficient microporous membrane equilibrator to minimize the system response time. The example profiles show <span class="hlt">vertical</span> <span class="hlt">gradients</span> in the upper 5 m for temperature, carbon dioxide and dimethylsulfide of 0.15 °C, 4 µatm and 0.4 nM respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22369831-freeze-through-portals','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22369831-freeze-through-portals"><span><span class="hlt">Freeze</span>-in through portals</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Blennow, Mattias; Fernandez-Martínez, Enrique; Zaldívar, Bryan, E-mail: emb@kth.se, E-mail: enrique.fernandez-martinez@uam.es, E-mail: b.zaldivar.m@csic.es</p> <p>2014-01-01</p> <p>The popular <span class="hlt">freeze</span>-out paradigm for Dark Matter (DM) production, relies on DM-baryon couplings of the order of the weak interactions. However, different search strategies for DM have failed to provide a conclusive evidence of such (non-gravitational) interactions, while greatly reducing the parameter space of many representative models. This motivates the study of alternative mechanisms for DM genesis. In the <span class="hlt">freeze</span>-in framework, the DM is slowly populated from the thermal bath while never reaching equilibrium. In this work, we analyse in detail the possibility of producing a frozen-in DM via a mediator particle which acts as a portal. We give analyticalmore » estimates of different <span class="hlt">freeze</span>-in regimes and support them with full numerical analyses, taking into account the proper distribution functions of bath particles. Finally, we constrain the parameter space of generic models by requiring agreement with DM relic abundance observations.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMGP42A..06C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMGP42A..06C"><span>New Methods For Interpretation Of Magnetic <span class="hlt">Gradient</span> Tensor Data Using Eigenalysis And The Normalized Source Strength</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Clark, D.</p> <p>2012-12-01</p> <p>In the future, acquisition of magnetic <span class="hlt">gradient</span> tensor data is likely to become routine. New methods developed for analysis of magnetic <span class="hlt">gradient</span> tensor data can also be applied to high quality conventional TMI surveys that have been processed using Fourier filtering techniques, or otherwise, to calculate magnetic vector and tensor components. This approach is, in fact, the only practical way at present to analyze vector component data, as measurements of vector components are seriously afflicted by motion noise, which is not as serious a problem for <span class="hlt">gradient</span> components. In many circumstances, an optimal approach to extracting maximum information from magnetic surveys would be to combine analysis of measured <span class="hlt">gradient</span> tensor data with vector components calculated from TMI measurements. New methods for inverting <span class="hlt">gradient</span> tensor surveys to obtain source parameters have been developed for a number of elementary, but useful, models. These include point dipole (sphere), <span class="hlt">vertical</span> line of dipoles (narrow <span class="hlt">vertical</span> pipe), line of dipoles (horizontal cylinder), thin dipping sheet, horizontal line current and contact models. A key simplification is the use of eigenvalues and associated eigenvectors of the tensor. The normalized source strength (NSS), calculated from the eigenvalues, is a particularly useful rotational invariant that peaks directly over 3D compact sources, 2D compact sources, thin sheets and contacts, and is independent of magnetization direction for these sources (and only very weakly dependent on magnetization direction in general). In combination the NSS and its vector <span class="hlt">gradient</span> enable estimation of the Euler structural index, thereby constraining source geometry, and determine source locations uniquely. NSS analysis can be extended to other useful models, such as <span class="hlt">vertical</span> pipes, by calculating eigenvalues of the <span class="hlt">vertical</span> derivative of the <span class="hlt">gradient</span> tensor. Once source locations are determined, information of source magnetizations can be obtained by simple</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14652223','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14652223"><span><span class="hlt">Freezing</span> tolerance of conifer seeds and germinants.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hawkins, B J; Guest, H J; Kolotelo, D</p> <p>2003-12-01</p> <p>Survival after <span class="hlt">freezing</span> was measured for seeds and germinants of four seedlots each of interior spruce (Picea glauca x engelmannii complex), lodgepole pine (Pinus contorta Dougl. ex Loud.), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and western red cedar (Thuja plicata Donn ex D. Donn). Effects of eight seed treatments on post-<span class="hlt">freezing</span> survival of seeds and germinants were tested: dry, imbibed and stratified seed, and seed placed in a growth chamber for 2, 5, 10, 15, 20 or 30 days in a 16-h photoperiod and a 22/17 degrees C thermoperiod. Survival was related to the water content of seeds and germinants, germination rate and seedlot origin. After <span class="hlt">freezing</span> for 3 h at -196 degrees C, dry seed of most seedlots of interior spruce, Douglas-fir and western red cedar had 84-96% germination, whereas lodgepole pine seedlots had 53-82% germination. <span class="hlt">Freezing</span> tolerance declined significantly after imbibition in lodgepole pine, Douglas-fir and interior spruce seed (western red cedar was not tested), and mean LT50 of imbibed seed of these species was -30, -24.5 and -20 degrees C, respectively. <span class="hlt">Freezing</span> tolerance continued to decline to a minimum LT50 of -4 to -7 degrees C after 10 days in a growth chamber for interior spruce, Douglas-fir and lodgepole pine, or after 15 days for western red cedar. Minimum <span class="hlt">freezing</span> tolerance was reached at the stage of rapid hypocotyl elongation. In all species, a slight increase in <span class="hlt">freezing</span> tolerance of germinants was observed once cotyledons emerged from the seed coat. The decrease in <span class="hlt">freezing</span> tolerance during the transition from dry to germinating seed correlated with increases in seed water content. Changes in <span class="hlt">freezing</span> tolerance between 10 and 30 days in the growth chamber were not correlated with seedling water content. Within a species, seedlots differed significantly in <span class="hlt">freezing</span> tolerance after 2 or 5 days in the growth chamber. Because all seedlots of interior spruce and lodgepole pine germinated quickly, there was no correlation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1415487-through-thickness-vertically-ordered-lamellar-block-copolymer-thin-films-unmodified-quartz-cold-zone-annealing-thru-thickness-vertically-ordered-lamellar-block-copolymer-thin-films-unmodified-quartz-cold-zone-annealing','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1415487-through-thickness-vertically-ordered-lamellar-block-copolymer-thin-films-unmodified-quartz-cold-zone-annealing-thru-thickness-vertically-ordered-lamellar-block-copolymer-thin-films-unmodified-quartz-cold-zone-annealing"><span>Through-Thickness <span class="hlt">Vertically</span> Ordered Lamellar Block Copolymer Thin Films on Unmodified Quartz with Cold Zone Annealing [Thru-Thickness <span class="hlt">Vertically</span> Ordered Lamellar Block Copolymer Thin Films on Unmodified Quartz with Cold Zone Annealing</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Basutkar, Monali N.; Samant, Saumil; Strzalka, Joseph</p> <p></p> <p>Here, template-free directed self-assembly of ultrathin (~10’s nm) lamellar block copolymer (l-BCP) films of high-interfacial area into <span class="hlt">vertically</span> oriented nanodomains holds much technological relevance for fabrication of next-generation devices from nanoelectronics to nanomembranes due to domain interconnectivity and high interfacial area. We report for the first time, the formation of full thru-thickness <span class="hlt">vertically</span> oriented lamellar domains in 100 nm thin polystyrene- block-poly(methyl methacrylate) (PS- b-PMMA) films on quartz substrate, achieved without any PMMA-block wetting layer formation, quartz surface modification (templating chemical, topographical) or system modifications (added surfactant, top-layer coat). <span class="hlt">Vertical</span> ordering of l-BCPs results from the coupling between a molecularmore » and a macroscopic phenomenon. A molecular relaxation induced <span class="hlt">vertical</span> l-BCP ordering occurs under a transient macroscopic <span class="hlt">vertical</span> strain field, imposed by a high film thermal expansion rate under sharp thermal <span class="hlt">gradient</span> cold zone annealing (CZA-S). The parametric window for <span class="hlt">vertical</span> ordering is quantified via a coupling constant, C (= v∇ T), whose range is established in terms of a thermal <span class="hlt">gradient</span> (∇ T) above a threshold value, and an optimal dynamic sample sweep rate ( v ~ d/τ), where τ is the l-BCP’s longest molecular relaxation time and d is the T g,heat- T g,cool distance. Real-time CZA-S morphology evolution of <span class="hlt">vertically</span> oriented l-BCP tracked along ∇ T using in-situ Grazing Incidence Small Angle X-ray Scattering exhibited an initial formation phase of <span class="hlt">vertical</span> lamellae, a polygrain structure formation stage, and a grain coarsening phase to fully <span class="hlt">vertically</span> ordered l-BCP morphology development. CZA-S is a roll-to-roll manufacturing method, rendering this template-free thru-thickness <span class="hlt">vertical</span> ordering of l-BCP films highly attractive and industrially relevant.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1415487-through-thickness-vertically-ordered-lamellar-block-copolymer-thin-films-unmodified-quartz-cold-zone-annealing-thru-thickness-vertically-ordered-lamellar-block-copolymer-thin-films-unmodified-quartz-cold-zone-annealing','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1415487-through-thickness-vertically-ordered-lamellar-block-copolymer-thin-films-unmodified-quartz-cold-zone-annealing-thru-thickness-vertically-ordered-lamellar-block-copolymer-thin-films-unmodified-quartz-cold-zone-annealing"><span>Through-Thickness <span class="hlt">Vertically</span> Ordered Lamellar Block Copolymer Thin Films on Unmodified Quartz with Cold Zone Annealing [Thru-Thickness <span class="hlt">Vertically</span> Ordered Lamellar Block Copolymer Thin Films on Unmodified Quartz with Cold Zone Annealing</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Basutkar, Monali N.; Samant, Saumil; Strzalka, Joseph; ...</p> <p>2017-11-14</p> <p>Here, template-free directed self-assembly of ultrathin (~10’s nm) lamellar block copolymer (l-BCP) films of high-interfacial area into <span class="hlt">vertically</span> oriented nanodomains holds much technological relevance for fabrication of next-generation devices from nanoelectronics to nanomembranes due to domain interconnectivity and high interfacial area. We report for the first time, the formation of full thru-thickness <span class="hlt">vertically</span> oriented lamellar domains in 100 nm thin polystyrene- block-poly(methyl methacrylate) (PS- b-PMMA) films on quartz substrate, achieved without any PMMA-block wetting layer formation, quartz surface modification (templating chemical, topographical) or system modifications (added surfactant, top-layer coat). <span class="hlt">Vertical</span> ordering of l-BCPs results from the coupling between a molecularmore » and a macroscopic phenomenon. A molecular relaxation induced <span class="hlt">vertical</span> l-BCP ordering occurs under a transient macroscopic <span class="hlt">vertical</span> strain field, imposed by a high film thermal expansion rate under sharp thermal <span class="hlt">gradient</span> cold zone annealing (CZA-S). The parametric window for <span class="hlt">vertical</span> ordering is quantified via a coupling constant, C (= v∇ T), whose range is established in terms of a thermal <span class="hlt">gradient</span> (∇ T) above a threshold value, and an optimal dynamic sample sweep rate ( v ~ d/τ), where τ is the l-BCP’s longest molecular relaxation time and d is the T g,heat- T g,cool distance. Real-time CZA-S morphology evolution of <span class="hlt">vertically</span> oriented l-BCP tracked along ∇ T using in-situ Grazing Incidence Small Angle X-ray Scattering exhibited an initial formation phase of <span class="hlt">vertical</span> lamellae, a polygrain structure formation stage, and a grain coarsening phase to fully <span class="hlt">vertically</span> ordered l-BCP morphology development. CZA-S is a roll-to-roll manufacturing method, rendering this template-free thru-thickness <span class="hlt">vertical</span> ordering of l-BCP films highly attractive and industrially relevant.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=280086','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=280086"><span>The equilibrated state of <span class="hlt">freezing</span> as a basis for distinguishing lethal stresses of <span class="hlt">freezing</span> in plants</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>A model for coordination of stresses that limit winterhardiness in plants based on the thermodynamic equilibrated state of <span class="hlt">freezing</span> and melting provides a rational basis for distinction of <span class="hlt">freeze</span>-induced energies which can stress and injure living organisms in various ways. The departure from equili...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/5932633-theory-freezing-simple-systems','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5932633-theory-freezing-simple-systems"><span>Theory of <span class="hlt">freezing</span> in simple systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Cerjan, C.; Bagchi, B.</p> <p></p> <p>The transition parameters for the <span class="hlt">freezing</span> of two one-component liquids into crystalline solids are evaluated by two theoretical approaches. The first system considered is liquid sodium which crystallizes into a body-centered-cubic (bcc) lattice; the second system is the <span class="hlt">freezing</span> of adhesive hard spheres into a face-centered-cubic (fcc) lattice. Two related theoretical techniques are used in this evaluation: One is based upon a recently developed bifurcation analysis; the other is based upon the theory of <span class="hlt">freezing</span> developed by Ramakrishnan and Yussouff. For liquid sodium, where experimental information is available, the predictions of the two theories agree well with experiment and eachmore » other. The adhesive-hard-sphere system, which displays a triple point and can be used to fit some liquids accurately, shows a temperature dependence of the <span class="hlt">freezing</span> parameters which is similar to Lennard-Jones systems. At very low temperature, the fractional density change on <span class="hlt">freezing</span> shows a dramatic increase as a function of temperature indicating the importance of all the contributions due to the triplet direction correlation function. Also, we consider the <span class="hlt">freezing</span> of a one-component liquid into a simple-cubic (sc) lattice by bifurcation analysis and show that this transition is highly unfavorable, independent of interatomic potential choice. The bifurcation diagrams for the three lattices considered are compared and found to be strikingly different. Finally, a new stability analysis of the bifurcation diagrams is presented.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29303327','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29303327"><span>Canceling the Gravity <span class="hlt">Gradient</span> Phase Shift in Atom Interferometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>D'Amico, G; Rosi, G; Zhan, S; Cacciapuoti, L; Fattori, M; Tino, G M</p> <p>2017-12-22</p> <p>Gravity <span class="hlt">gradients</span> represent a major obstacle in high-precision measurements by atom interferometry. Controlling their effects to the required stability and accuracy imposes very stringent requirements on the relative positioning of freely falling atomic clouds, as in the case of precise tests of Einstein's equivalence principle. We demonstrate a new method to exactly compensate the effects introduced by gravity <span class="hlt">gradients</span> in a Raman-pulse atom interferometer. By shifting the frequency of the Raman lasers during the central π pulse, it is possible to cancel the initial position- and velocity-dependent phase shift produced by gravity <span class="hlt">gradients</span>. We apply this technique to simultaneous interferometers positioned along the <span class="hlt">vertical</span> direction and demonstrate a new method for measuring local gravity <span class="hlt">gradients</span> that does not require precise knowledge of the relative position between the atomic clouds. Based on this method, we also propose an improved scheme to determine the Newtonian gravitational constant G towards the 10 ppm relative uncertainty.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvL.119y3201D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvL.119y3201D"><span>Canceling the Gravity <span class="hlt">Gradient</span> Phase Shift in Atom Interferometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>D'Amico, G.; Rosi, G.; Zhan, S.; Cacciapuoti, L.; Fattori, M.; Tino, G. M.</p> <p>2017-12-01</p> <p>Gravity <span class="hlt">gradients</span> represent a major obstacle in high-precision measurements by atom interferometry. Controlling their effects to the required stability and accuracy imposes very stringent requirements on the relative positioning of freely falling atomic clouds, as in the case of precise tests of Einstein's equivalence principle. We demonstrate a new method to exactly compensate the effects introduced by gravity <span class="hlt">gradients</span> in a Raman-pulse atom interferometer. By shifting the frequency of the Raman lasers during the central π pulse, it is possible to cancel the initial position- and velocity-dependent phase shift produced by gravity <span class="hlt">gradients</span>. We apply this technique to simultaneous interferometers positioned along the <span class="hlt">vertical</span> direction and demonstrate a new method for measuring local gravity <span class="hlt">gradients</span> that does not require precise knowledge of the relative position between the atomic clouds. Based on this method, we also propose an improved scheme to determine the Newtonian gravitational constant G towards the 10 ppm relative uncertainty.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22969755','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22969755"><span>Light <span class="hlt">gradients</span> and optical microniches in coral tissues.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wangpraseurt, Daniel; Larkum, Anthony W D; Ralph, Peter J; Kühl, Michael</p> <p>2012-01-01</p> <p>Light quantity and quality are among the most important factors determining the physiology and stress response of zooxanthellate corals. Yet, almost nothing is known about the light field that Symbiodinium experiences within their coral host, and the basic optical properties of coral tissue are unknown. We used scalar irradiance microprobes to characterize <span class="hlt">vertical</span> and lateral light <span class="hlt">gradients</span> within and across tissues of several coral species. Our results revealed the presence of steep light <span class="hlt">gradients</span> with photosynthetically available radiation decreasing by about one order of magnitude from the tissue surface to the coral skeleton. Surface scalar irradiance was consistently higher over polyp tissue than over coenosarc tissue in faviid corals. Coral bleaching increased surface scalar irradiance by ~150% (between 500 and 700 nm) relative to a healthy coral. Photosynthesis peaked around 300 μm within the tissue, which corresponded to a zone exhibiting strongest depletion of scalar irradiance. Deeper coral tissue layers, e.g., ~1000 μm into aboral polyp tissues, harbor optical microniches, where only ~10% of the incident irradiance remains. We conclude that the optical microenvironment of corals exhibits strong lateral and <span class="hlt">vertical</span> <span class="hlt">gradients</span> of scalar irradiance, which are affected by both tissue and skeleton optical properties. Our results imply that zooxanthellae populations inhabit a strongly heterogeneous light environment and highlight the presence of different optical microniches in corals; an important finding for understanding the photobiology, stress response, as well as the phenotypic and genotypic plasticity of coral symbionts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3427877','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3427877"><span>Light <span class="hlt">gradients</span> and optical microniches in coral tissues</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wangpraseurt, Daniel; Larkum, Anthony W. D.; Ralph, Peter J.; Kühl, Michael</p> <p>2012-01-01</p> <p>Light quantity and quality are among the most important factors determining the physiology and stress response of zooxanthellate corals. Yet, almost nothing is known about the light field that Symbiodinium experiences within their coral host, and the basic optical properties of coral tissue are unknown. We used scalar irradiance microprobes to characterize <span class="hlt">vertical</span> and lateral light <span class="hlt">gradients</span> within and across tissues of several coral species. Our results revealed the presence of steep light <span class="hlt">gradients</span> with photosynthetically available radiation decreasing by about one order of magnitude from the tissue surface to the coral skeleton. Surface scalar irradiance was consistently higher over polyp tissue than over coenosarc tissue in faviid corals. Coral bleaching increased surface scalar irradiance by ~150% (between 500 and 700 nm) relative to a healthy coral. Photosynthesis peaked around 300 μm within the tissue, which corresponded to a zone exhibiting strongest depletion of scalar irradiance. Deeper coral tissue layers, e.g., ~1000 μm into aboral polyp tissues, harbor optical microniches, where only ~10% of the incident irradiance remains. We conclude that the optical microenvironment of corals exhibits strong lateral and <span class="hlt">vertical</span> <span class="hlt">gradients</span> of scalar irradiance, which are affected by both tissue and skeleton optical properties. Our results imply that zooxanthellae populations inhabit a strongly heterogeneous light environment and highlight the presence of different optical microniches in corals; an important finding for understanding the photobiology, stress response, as well as the phenotypic and genotypic plasticity of coral symbionts. PMID:22969755</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27037941','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27037941"><span>Hexagonal <span class="hlt">gradient</span> scheme with RF spoiling improves spoiling performance for high-flip-angle fast <span class="hlt">gradient</span> echo imaging.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hess, Aaron T; Robson, Matthew D</p> <p>2017-03-01</p> <p>To present a framework in which time-varying <span class="hlt">gradients</span> are applied with RF spoiling to reduce unwanted signal, particularly at high flip angles. A time-varying <span class="hlt">gradient</span> spoiler scheme compatible with RF spoiling is defined, in which spoiler <span class="hlt">gradients</span> cycle through the <span class="hlt">vertices</span> of a hexagon, which we call hexagonal spoiling. The method is compared with a traditional constant spoiling <span class="hlt">gradient</span> both in the transition to and in the steady state. Extended phase graph (EPG) simulations, phantom acquisitions, and in vivo images were used to assess the method. Simulations, phantom and in vivo experiments showed that unwanted signal was markedly reduced by employing hexagonal spoiling, both in the transition to and in the steady state. For adipose tissue at 1.5 Tesla, the unwanted signal in the steady state with a 60 ° flip angle was reduced from 22% with constant spoiling to 2% with hexagonal spoiling. A time-varying <span class="hlt">gradient</span> spoiler scheme that works with RF spoiling, called "hexagonal spoiling," has been presented and found to offer improved spoiling over the traditional constant spoiling <span class="hlt">gradient</span>. Magn Reson Med 77:1231-1237, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3757462','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3757462"><span><span class="hlt">Vertical</span> heterogeneity in predation pressure in a temperate forest canopy</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Aikens, Kathleen R.; Buddle, Christopher M.</p> <p>2013-01-01</p> <p>The forest canopy offers a <span class="hlt">vertical</span> <span class="hlt">gradient</span> across which variation in predation pressure implies variation in refuge quality for arthropods. Direct and indirect experimental approaches were combined to assess whether canopy strata differ in ability to offer refuge to various arthropod groups. <span class="hlt">Vertical</span> heterogeneity in impact of avian predators was quantified using exclosure cages in the understory, lower, mid, and upper canopy of a north-temperate deciduous forest near Montreal, Quebec. Bait trials were completed in the same strata to investigate the effects of invertebrate predators. Exclusion of birds yielded higher arthropod densities across all strata, although treatment effects were small for some taxa. Observed <span class="hlt">gradients</span> in predation pressure were similar for both birds and invertebrate predators; the highest predation pressure was observed in the understory and decreased with height. Our findings support a view of the forest canopy that is heterogeneous with respect to arthropod refuge from natural enemies. PMID:24010017</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1489628','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1489628"><span>Depth-Related <span class="hlt">Gradients</span> of Viral Activity in Lake Pavin</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Colombet, J.; Sime-Ngando, T.; Cauchie, H. M.; Fonty, G.; Hoffmann, L.; Demeure, G.</p> <p>2006-01-01</p> <p>High-resolution <span class="hlt">vertical</span> sampling and determination of viral and prokaryotic parameters in a deep volcanic lake shows that in the absence of thermal stratification but within light, oxygen, and chlorophyll <span class="hlt">gradients</span>, host availability empirically is prevalent over the physical and chemical environments and favors lytic over lysogenic “viral life cycles.” PMID:16751565</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..4412244B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..4412244B"><span>Tracking the Subsurface Signal of Decadal Climate Warming to Quantify <span class="hlt">Vertical</span> Groundwater Flow Rates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bense, V. F.; Kurylyk, B. L.</p> <p>2017-12-01</p> <p>Sustained ground surface warming on a decadal time scale leads to an inversion of thermal <span class="hlt">gradients</span> in the upper tens of meters. The magnitude and direction of <span class="hlt">vertical</span> groundwater flow should influence the propagation of this warming signal, but direct field observations of this phenomenon are rare. Comparison of temperature-depth profiles in boreholes in the Veluwe area, Netherlands, collected in 1978-1982 and 2016 provided such direct measurement. We used these repeated profiles to track the downward propagation rate of the depth at which the thermal <span class="hlt">gradient</span> is zero. Numerical modeling of the migration of this thermal <span class="hlt">gradient</span> "inflection point" yielded estimates of downward groundwater flow rates (0-0.24 m a-1) that generally concurred with known hydrogeological conditions in the area. We conclude that analysis of inflection point depths in temperature-depth profiles impacted by surface warming provides a largely untapped opportunity to inform sustainable groundwater management plans that rely on accurate estimates of long-term <span class="hlt">vertical</span> groundwater fluxes.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870049903&hterms=mobil&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmobil','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870049903&hterms=mobil&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmobil"><span>Rate limits in silicon sheet growth - The connections between <span class="hlt">vertical</span> and horizontal methods</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Thomas, Paul D.; Brown, Robert A.</p> <p>1987-01-01</p> <p>Meniscus-defined techniques for the growth of thin silicon sheets fall into two categories: <span class="hlt">vertical</span> and horizontal growth. The interactions of the temperature field and the crystal shape are analyzed for both methods using two-dimensional finite-element models which include heat transfer and capillarity. Heat transfer in <span class="hlt">vertical</span> growth systems is dominated by conduction in the melt and the crystal, with almost flat melt/crystal interfaces that are perpendicular to the direction of growth. The high axial temperature <span class="hlt">gradients</span> characteristic of <span class="hlt">vertical</span> growth lead to high thermal stresses. The maximum growth rate is also limited by capillarity which can restrict the conduction of heat from the melt into the crystal. In horizontal growth the melt/crystal interface stretches across the surface of the melt pool many times the crystal thickness, and low growth rates are achievable with careful temperature control. With a moderate axial temperature <span class="hlt">gradient</span> in the sheet a substantial portion of the latent heat conducts along the sheet and the surface of the melt pool becomes supercooled, leading to dendritic growth. The thermal supercooling is surpressed by lowering the axial <span class="hlt">gradient</span> in the crystal; this configuration is the most desirable for the growth of high quality crystals. An expression derived from scaling analysis relating the growth rate and the crucible temperature is shown to be reliable for horizontal growth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19710000258','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19710000258"><span>Modification of physical properties of <span class="hlt">freeze</span>-dried rice</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Huber, C. S.</p> <p>1971-01-01</p> <p><span class="hlt">Freeze</span> cycling process consists of alternately <span class="hlt">freezing</span> and thawing precooked rice for two cycles, rice is then frozen and <span class="hlt">freeze</span>-dehydrated in vacuum sufficient to remove water from rice by sublimitation. Process modifies rice grain structure and porosity, enabling complete rehydration in one minute in hot water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AdWR..112...72B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AdWR..112...72B"><span>Modeling chemical <span class="hlt">gradients</span> in sediments under losing and gaining flow conditions: The <span class="hlt">GRADIENT</span> code</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Boano, Fulvio; De Falco, Natalie; Arnon, Shai</p> <p>2018-02-01</p> <p>Interfaces between sediments and water bodies often represent biochemical hotspots for nutrient reactions and are characterized by steep concentration <span class="hlt">gradients</span> of different reactive solutes. <span class="hlt">Vertical</span> profiles of these concentrations are routinely collected to obtain information on nutrient dynamics, and simple codes have been developed to analyze these profiles and determine the magnitude and distribution of reaction rates within sediments. However, existing publicly available codes do not consider the potential contribution of water flow in the sediments to nutrient transport, and their applications to field sites with significant water-borne nutrient fluxes may lead to large errors in the estimated reaction rates. To fill this gap, the present work presents <span class="hlt">GRADIENT</span>, a novel algorithm to evaluate distributions of reaction rates from observed concentration profiles. <span class="hlt">GRADIENT</span> is a Matlab code that extends a previously published framework to include the role of nutrient advection, and provides robust estimates of reaction rates in sediments with significant water flow. This work discusses the theoretical basis of the method and shows its performance by comparing the results to a series of synthetic data and to laboratory experiments. The results clearly show that in systems with losing or gaining fluxes, the inclusion of such fluxes is critical for estimating local and overall reaction rates in sediments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11042082','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11042082"><span>Ultrastructure of sea urchin calcified tissues after high-pressure <span class="hlt">freezing</span> and <span class="hlt">freeze</span> substitution.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ameye, L; Hermann, R; Dubois, P</p> <p>2000-08-01</p> <p>The improvements brought by high-pressure <span class="hlt">freezing/freeze</span> substitution fixation methods to the ultrastructural preservation of echinoderm mineralized tissues are investigated in developing pedicellariae and teeth of the echinoid Paracentrotus lividus. Three <span class="hlt">freeze</span> substitution (FS) protocols were tested: one in the presence of osmium tetroxide, one in the presence of uranyl acetate, and the last in the presence of gallic acid. FS in the presence of osmium tetroxide significantly improved cell ultrastructure preservation and should especially be used for ultrastructural studies involving vesicles and the Golgi apparatus. With all protocols, multivesicular bodies, suggested to contain Ca(2+), were evident for the first time in skeleton-forming cells. FS in the presence of gallic acid allowed us to confirm the structured and insoluble character of a part of the organic matrix of mineralization in the calcification sites of the tooth, an observation which modifies the current understanding of biomineralization control in echinoderms. Copyright 2000 Academic Press.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/21559853-two-dimensional-freezing-criteria-crystallizing-colloidal-monolayers','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/21559853-two-dimensional-freezing-criteria-crystallizing-colloidal-monolayers"><span>Two-dimensional <span class="hlt">freezing</span> criteria for crystallizing colloidal monolayers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Wang Ziren; Han Yilong; Alsayed, Ahmed M.</p> <p></p> <p>Video microscopy was employed to explore crystallization of colloidal monolayers composed of diameter-tunable microgel spheres. Two-dimensional (2D) colloidal liquids were frozen homogenously into polycrystalline solids, and four 2D criteria for <span class="hlt">freezing</span> were experimentally tested in thermal systems for the first time: the Hansen-Verlet <span class="hlt">freezing</span> rule, the Loewen-Palberg-Simon dynamical <span class="hlt">freezing</span> criterion, and two other rules based, respectively, on the split shoulder of the radial distribution function and on the distribution of the shape factor of Voronoi polygons. Importantly, these <span class="hlt">freezing</span> criteria, usually applied in the context of single crystals, were demonstrated to apply to the formation of polycrystalline solids. At themore » <span class="hlt">freezing</span> point, we also observed a peak in the fluctuations of the orientational order parameter and a percolation transition associated with caged particles. Speculation about these percolated clusters of caged particles casts light on solidification mechanisms and dynamic heterogeneity in <span class="hlt">freezing</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.water.usgs.gov/sir2004-5053/','USGSPUBS'); return false;" href="http://pubs.water.usgs.gov/sir2004-5053/"><span><span class="hlt">Vertical</span> <span class="hlt">Gradients</span> in Water Chemistry and Age in the Southern High Plains Aquifer, Texas, 2002</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>McMahon, P.B.; Böhlke, J.K.; Lehman, T.M.</p> <p>2004-01-01</p> <p>The southern High Plains aquifer is the primary source of water used for domestic, industrial, and irrigation purposes in parts of New Mexico and Texas. Despite the aquifer's importance to the overall economy of the southern High Plains, fundamental ground-water characteristics, such as <span class="hlt">vertical</span> <span class="hlt">gradients</span> in water chemistry and age, remain poorly defined. As part of the U.S. Geological Survey's National Water-Quality Assessment Program, water samples from nested, short-screen monitoring wells installed in the southern High Plains aquifer at two locations (Castro and Hale Counties, Texas) were analyzed for field parameters, major ions, nutrients, trace elements, dissolved organic carbon, pesticides, stable and radioactive isotopes, and dissolved gases to evaluate <span class="hlt">vertical</span> <span class="hlt">gradients</span> in water chemistry and age in the aquifer. Tritium measurements indicate that recent (post-1953) recharge was present near the water table and that deeper water was recharged before 1953. Concentrations of dissolved oxygen were largest (2.6 to 5.6 milligrams per liter) at the water table and decreased with depth below the water table. The smallest concentrations were less than 0.5 milligram per liter. The largest major-ion concentrations generally were detected at the water table because of the effects of overlying agricultural activities, as indicated by postbomb tritium concentrations and elevated nitrate and pesticide concentrations at the water table. Below the zone of agricultural influence, major-ion concentrations exhibited small increases with depth and distance along flow paths because of rock/water interactions and mixing with water from the underlying aquifer in rocks of Cretaceous age. The concentration increases primarily were accounted for by dissolved sodium, bicarbonate, chloride, and sulfate. Nitrite plus nitrate concentrations at the water table were 2.0 to 6.1 milligrams per liter as nitrogen, and concentrations substantially decreased with depth in the aquifer to a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007JGeod..81..403B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007JGeod..81..403B"><span>Troposphere <span class="hlt">gradients</span> from the ECMWF in VLBI analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Boehm, Johannes; Schuh, Harald</p> <p>2007-06-01</p> <p>Modeling path delays in the neutral atmosphere for the analysis of Very Long Baseline Interferometry (VLBI) observations has been improved significantly in recent years by the use of elevation-dependent mapping functions based on data from numerical weather models. In this paper, we present a fast way of extracting both, hydrostatic and wet, linear horizontal <span class="hlt">gradients</span> for the troposphere from data of the European Centre for Medium-range Weather Forecasts (ECMWF) model, as it is realized at the Vienna University of Technology on a routine basis for all stations of the International GNSS (Global Navigation Satellite Systems) Service (IGS) and International VLBI Service for Geodesy and Astrometry (IVS) stations. This approach only uses information about the refractivity <span class="hlt">gradients</span> at the site <span class="hlt">vertical</span>, but no information from the line-of-sight. VLBI analysis of the CONT02 and CONT05 campaigns, as well as all IVS-R1 and IVS-R4 sessions in the first half of 2006, shows that fixing these a priori <span class="hlt">gradients</span> improves the repeatability for 74% (40 out of 54) of the VLBI baseline lengths compared to fixing zero or constant a priori <span class="hlt">gradients</span>, and improves the repeatability for the majority of baselines compared to estimating 24-h offsets for the <span class="hlt">gradients</span>. Only if 6-h offsets are estimated, the baseline length repeatabilities significantly improve, no matter which a priori <span class="hlt">gradients</span> are used.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3833302','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3833302"><span>Optimum Parameters for <span class="hlt">Freeze</span>-Drying Decellularized Arterial Scaffolds</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sheridan, William S.; Duffy, Garry P.</p> <p>2013-01-01</p> <p>Decellularized arterial scaffolds have achieved success in advancing toward clinical use as vascular grafts. However, concerns remain regarding long-term preservation and sterilization of these scaffolds. <span class="hlt">Freeze</span> drying offers a means of overcoming these concerns. In this study, we investigated the effects of various <span class="hlt">freeze</span>-drying protocols on decellularized porcine carotid arteries and consequently, determined the optimum parameters to fabricate a stable, preserved scaffold with unaltered mechanical properties. <span class="hlt">Freeze</span> drying by constant slow cooling to two final temperatures ((Tf), −10°C and −40°C) versus instant <span class="hlt">freezing</span> was investigated by histological examination and mechanical testing. Slow cooling to Tf= −10°C produced a stiffer and less distensible response than the non <span class="hlt">freeze</span>-dried scaffolds and resulted in disruption to the collagen fibers. The mechanical response of Tf= −40°C scaffolds demonstrated disruption to the elastin network, which was confirmed with histology. Snap <span class="hlt">freezing</span> scaffolds in liquid nitrogen and <span class="hlt">freeze</span> drying to Tf= −40°C with a precooled shelf at −60°C produced scaffolds with unaltered mechanical properties and a histology resembling non-<span class="hlt">freeze</span>-dried scaffolds. The results of this study demonstrate the importance of optimizing the nucleation and ice crystal growth/size to ensure homogenous drying, preventing extracellular matrix disruption and subsequent inferior mechanical properties. This new manufacturing protocol creates the means for the preservation and sterilization of decellularized arterial scaffolds while simultaneously maintaining the mechanical properties of the tissue. PMID:23614758</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040171254','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040171254"><span>Note on the Effect of Horizontal <span class="hlt">Gradients</span> for Nadir-Viewing Microwave and Infrared Sounders</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Joiner, J.; Poli, P.</p> <p>2004-01-01</p> <p>Passive microwave and infrared nadir sounders such as the Advanced Microwave Sounding Unit A (AMSU-A) and the Atmospheric InfraRed Sounder (AIRS), both flying on NASA s EOS Aqua satellite, provide information about <span class="hlt">vertical</span> temperature and humidity structure that is used in data assimilation systems for numerical weather prediction and climate applications. These instruments scan cross track so that at the satellite swath edges, the satellite zenith angles can reach approx. 60 deg. The emission path through the atmosphere as observed by the satellite is therefore slanted with respect to the satellite footprint s zenith. Although radiative transfer codes currently in use at operational centers use the appropriate satellite zenith angle to compute brightness temperature, the input atmospheric fields are those from the <span class="hlt">vertical</span> profile above the center of the satellite footprint. If horizontal <span class="hlt">gradients</span> are present in the atmospheric fields, the use of a <span class="hlt">vertical</span> atmospheric profile may produce an error. This note attempts to quantify the effects of horizontal <span class="hlt">gradients</span> on AIRS and AMSU-A channels by computing brightness temperatures with accurate slanted atmospheric profiles. We use slanted temperature, water vapor, and ozone fields from data assimilation systems. We compare the calculated slanted and <span class="hlt">vertical</span> brightness temperatures with AIRS and AMSU-A observations. We show that the effects of horizontal <span class="hlt">gradients</span> on these sounders are generally small and below instrument noise. However, there are cases where the effects are greater than the instrument noise and may produce erroneous increments in an assimilation system. The majority of the affected channels have weighting functions that peak in the upper troposphere (water vapor sensitive channels) and above (temperature sensitive channels) and are unlikely t o significantly impact tropospheric numerical weather prediction. However, the errors could be significant for other applications such as stratospheric</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1344234-convective-cloud-vertical-velocity-mass-flux-characteristics-from-radar-wind-profiler-observations-during-goamazon2014-vertical-velocity-goamazon2014','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1344234-convective-cloud-vertical-velocity-mass-flux-characteristics-from-radar-wind-profiler-observations-during-goamazon2014-vertical-velocity-goamazon2014"><span>Convective cloud <span class="hlt">vertical</span> velocity and mass-flux characteristics from radar wind profiler observations during GoAmazon2014/5: <span class="hlt">VERTICAL</span> VELOCITY GOAMAZON2014/5</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Giangrande, Scott E.; Toto, Tami; Jensen, Michael P.; ...</p> <p>2016-11-15</p> <p>A radar wind profiler data set collected during the 2 year Department of Energy Atmospheric Radiation Measurement Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) campaign is used to estimate convective cloud <span class="hlt">vertical</span> velocity, area fraction, and mass flux profiles. <span class="hlt">Vertical</span> velocity observations are presented using cumulative frequency histograms and weighted mean profiles to provide insights in a manner suitable for global climate model scale comparisons (spatial domains from 20 km to 60 km). Convective profile sensitivity to changes in environmental conditions and seasonal regime controls is also considered. Aggregate and ensemble average <span class="hlt">vertical</span> velocity, convective area fraction, andmore » mass flux profiles, as well as magnitudes and relative profile behaviors, are found consistent with previous studies. Updrafts and downdrafts increase in magnitude with height to midlevels (6 to 10 km), with updraft area also increasing with height. Updraft mass flux profiles similarly increase with height, showing a peak in magnitude near 8 km. Downdrafts are observed to be most frequent below the <span class="hlt">freezing</span> level, with downdraft area monotonically decreasing with height. Updraft and downdraft profile behaviors are further stratified according to environmental controls. These results indicate stronger <span class="hlt">vertical</span> velocity profile behaviors under higher convective available potential energy and lower low-level moisture conditions. Sharp contrasts in convective area fraction and mass flux profiles are most pronounced when retrievals are segregated according to Amazonian wet and dry season conditions. During this deployment, wet season regimes favored higher domain mass flux profiles, attributed to more frequent convection that offsets weaker average convective cell <span class="hlt">vertical</span> velocities.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997JCrGr.171..373J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997JCrGr.171..373J"><span>Amplitudes of doping striations: comparison of numerical calculations and analytical approaches</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jung, T.; Müller, G.</p> <p>1997-02-01</p> <p>Transient, axisymmetric numerical calculations of the heat and species transport including convection were performed for a simplified <span class="hlt">vertical</span> <span class="hlt">gradient</span> <span class="hlt">freeze</span> (Bridgman) process with bottom seeding for GaAs. Periodical oscillations were superimposed onto the transient heater temperature profile. The amplitudes of the resulting oscillations of the growth rate and the dopant concentration (striations) in the growing crystals are compared with the predictions of analytical models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title7-vol3/pdf/CFR-2013-title7-vol3-sec58-620.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title7-vol3/pdf/CFR-2013-title7-vol3-sec58-620.pdf"><span>7 CFR 58.620 - <span class="hlt">Freezing</span> and packaging rooms.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-01-01</p> <p>... 7 Agriculture 3 2013-01-01 2013-01-01 false <span class="hlt">Freezing</span> and packaging rooms. 58.620 Section 58.620... Specifications for Dairy Plants Approved for USDA Inspection and Grading Service 1 Rooms and Compartments § 58.620 <span class="hlt">Freezing</span> and packaging rooms. The rooms used for <span class="hlt">freezing</span> and packaging frozen desserts shall be...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title7-vol3/pdf/CFR-2014-title7-vol3-sec58-620.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title7-vol3/pdf/CFR-2014-title7-vol3-sec58-620.pdf"><span>7 CFR 58.620 - <span class="hlt">Freezing</span> and packaging rooms.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-01-01</p> <p>... 7 Agriculture 3 2014-01-01 2014-01-01 false <span class="hlt">Freezing</span> and packaging rooms. 58.620 Section 58.620... Specifications for Dairy Plants Approved for USDA Inspection and Grading Service 1 Rooms and Compartments § 58.620 <span class="hlt">Freezing</span> and packaging rooms. The rooms used for <span class="hlt">freezing</span> and packaging frozen desserts shall be...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title7-vol3/pdf/CFR-2012-title7-vol3-sec58-620.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title7-vol3/pdf/CFR-2012-title7-vol3-sec58-620.pdf"><span>7 CFR 58.620 - <span class="hlt">Freezing</span> and packaging rooms.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-01-01</p> <p>... 7 Agriculture 3 2012-01-01 2012-01-01 false <span class="hlt">Freezing</span> and packaging rooms. 58.620 Section 58.620... Specifications for Dairy Plants Approved for USDA Inspection and Grading Service 1 Rooms and Compartments § 58.620 <span class="hlt">Freezing</span> and packaging rooms. The rooms used for <span class="hlt">freezing</span> and packaging frozen desserts shall be...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol5/pdf/CFR-2010-title7-vol5-sec305-18.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol5/pdf/CFR-2010-title7-vol5-sec305-18.pdf"><span>7 CFR 305.18 - Quick <span class="hlt">freeze</span> treatment schedule.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... 7 Agriculture 5 2010-01-01 2010-01-01 false Quick <span class="hlt">freeze</span> treatment schedule. 305.18 Section 305.18... SERVICE, DEPARTMENT OF AGRICULTURE PHYTOSANITARY TREATMENTS Quick <span class="hlt">Freeze</span> Treatments § 305.18 Quick <span class="hlt">freeze</span> treatment schedule. (a) T110. (1) Initially, lower the commodity's temperature to 0 °F or below. (2) Hold...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA196007','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA196007"><span>References on Compression of <span class="hlt">Freeze</span>-Dried Foods</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1978-08-01</p> <p>ready-to-eat, <span class="hlt">freeze</span>-dried scrambled egg . Swift and Co., Contract No. DA 19- 129-AMC-121. 67-49-FD (FD-54). January 1967 (AD 650637). In the design...significantly poorer in organoleptic properties than from grades A and B eggs. <span class="hlt">Freeze</span>- dried scrambled egg packed in cans kept better in storage than when...scrambled, cooked, <span class="hlt">freeze</span>-dried whole egg product was developed which possessed the appearance, aroma, flavor and texture similar to pan- fried scrambled</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29851297','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29851297"><span>Protective effect of sugars on storage stability of microwave <span class="hlt">freeze</span>-dried and <span class="hlt">freeze</span>-dried Lactobacillus paracasei F19.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ambros, S; Hofer, F; Kulozik, U</p> <p>2018-05-31</p> <p>Microwave <span class="hlt">freeze</span> drying in comparison to conventional <span class="hlt">freeze</span> drying allows for intensification of the preservation process of lactic acid bacteria without imposing additional processing stress. Viability as a function of storage time of microwave <span class="hlt">freeze</span>-dried Lactobacillus paracasei ssp. paracasei F19 was investigated in comparison to conventionally lyophilized bacteria of the same strain. Further, the impact of the protectants, sorbitol, trehalose and maltodextrin, on shelf life was analyzed. The highest inactivation rates of 0.035 and 0.045 d -1 , respectively, were found for cultures without protectants. Thus, all additives were found to exhibit a protective effect during storage with inactivation rates between 0.015 and 0.040 d -1 . Although trehalose and maltodextrin samples were in the glassy state during storage, in contrast to samples containing sorbitol as protectant, the best protective effect could be found for sorbitol with the lowest inactivation rate of 0.015 d -1 . Due to its low molecular weight, it might protect cells owing to better adsorption to the cytoplasma membrane. Sorbitol additionally shows antioxidative properties. Storage behavior of microwave <span class="hlt">freeze</span>-dried cultures follows the typical behavior of a product dried by conventional lyophilization. No significant influence of the drying technique on storage behavior was detected. General findings concerning storage behavior in <span class="hlt">freeze</span> drying are likely to be applicable in microwave <span class="hlt">freeze</span> drying with only slight adjustments. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26463561','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26463561"><span>Recent developments in smart <span class="hlt">freezing</span> technology applied to fresh foods.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xu, Ji-Cheng; Zhang, Min; Mujumdar, Arun S; Adhikari, Benu</p> <p>2017-09-02</p> <p>Due to the increased awareness of consumers in sensorial and nutritional quality of frozen foods, the <span class="hlt">freezing</span> technology has to seek new and innovative technologies for better retaining the fresh like quality of foods. In this article, we review the recent developments in smart <span class="hlt">freezing</span> technology applied to fresh foods. The application of these intelligent technologies and the associated underpinning concepts have greatly improved the quality of frozen foods and the <span class="hlt">freezing</span> efficiency. These technologies are able to automatically collect the information in-line during <span class="hlt">freezing</span> and help control the <span class="hlt">freezing</span> process better. Smart <span class="hlt">freezing</span> technology includes new and intelligent technologies and concepts applied to the pretreatment of the frozen product, <span class="hlt">freezing</span> processes, cold chain logistics as well as warehouse management. These technologies enable real-time monitoring of quality during the <span class="hlt">freezing</span> process and help improve product quality and <span class="hlt">freezing</span> efficiency. We also provide a brief overview of several sensing technologies used to achieve automatic control of individual steps of <span class="hlt">freezing</span> process. These sensing technologies include computer vision, electronic nose, electronic tongue, digital simulation, confocal laser, near infrared spectroscopy, nuclear magnetic resonance technology and ultrasound. Understanding of the mechanism of these new technologies will be helpful for applying them to improve the quality of frozen foods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19740040341&hterms=conjugate+gradient&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dconjugate%2Bgradient','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19740040341&hterms=conjugate+gradient&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dconjugate%2Bgradient"><span>Aircraft symmetric flight optimization. [<span class="hlt">gradient</span> techniques for supersonic aircraft control</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Falco, M.; Kelley, H. J.</p> <p>1973-01-01</p> <p>Review of the development of <span class="hlt">gradient</span> techniques and their application to aircraft optimal performance computations in the <span class="hlt">vertical</span> plane of flight. Results obtained using the method of <span class="hlt">gradients</span> are presented for attitude- and throttle-control programs which extremize the fuel, range, and time performance indices subject to various trajectory and control constraints, including boundedness of engine throttle control. A penalty function treatment of state inequality constraints which generally appear in aircraft performance problems is outlined. Numerical results for maximum-range, minimum-fuel, and minimum-time climb paths for a hypothetical supersonic turbojet interceptor are presented and discussed. In addition, minimum-fuel climb paths subject to various levels of ground overpressure intensity constraint are indicated for a representative supersonic transport. A variant of the Gel'fand-Tsetlin 'method of ravines' is reviewed, and two possibilities for further development of continuous <span class="hlt">gradient</span> processes are cited - namely, a projection version of conjugate <span class="hlt">gradients</span> and a curvilinear search.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1911495B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1911495B"><span>Control of topography <span class="hlt">gradients</span> on residence time distributions, mixing dynamics and reactive hotspot development</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bandopadhyay, Aditya; Le Borgne, Tanguy; Davy, Philippe</p> <p>2017-04-01</p> <p>Topography-driven subsurface flows are thought to play a central role in determining solute turnover and biogeochemical processes at different scales in the critical zone, including river-hyporheic zone exchanges, hillslope solute transport and reactions, and catchment biogeochemical cycles. Hydraulic head <span class="hlt">gradients</span>, induced by topography <span class="hlt">gradients</span> at different scales, generate a distribution of streamlines at depth, dictating the spatial distribution of redox sensitive species, the magnitude of surface water - ground water exchanges and ultimately the source/sink function of the subsurface. Flow velocities generally decrease with depth, leading to broad residence time distributions, which have been shown to affect river chemistry and geochemical reactions in catchments. In this presentation, we discuss the impact of topography-driven flows on mixing processes and the formation of localized reactive hotspots. For this, we solve analytically the coupled flow, mixing and reaction equations in two-dimensional <span class="hlt">vertical</span> cross-sections of subsurface domains with different topography <span class="hlt">gradients</span>. For a given topography <span class="hlt">gradient</span>, we derive the spatial distribution of subsurface velocities, the rates of solute mixing accross streamlines and the induced kinetics of redox, precipitation and dissolution reactions using a Lagrangian approach (Le Borgne et al. 2014). We demonstrate that <span class="hlt">vertical</span> velocity profiles driven by topography variations, act effectively as shear flows, hence stretching continuously the mixing fronts between recently infiltrated and resident water (Bandopadhyay et al. 2017). We thus derive analytical expressions for residence time distributions, mixing rates and kinetics of chemical reactions as a function of the topography <span class="hlt">gradients</span>. We show that the rates dissolution and precipitation reactions are significantly enhanced by the existence of <span class="hlt">vertical</span> velocity <span class="hlt">gradients</span> and that reaction rates reach a maximum in a localized subsurface reactive layer, whose</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18080464','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18080464"><span><span class="hlt">Freeze</span>-drying of yeast cultures.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bond, Chris</p> <p>2007-01-01</p> <p>A method is described that allows yeast species to be stored using a variation on the standard <span class="hlt">freeze</span>-drying method, which employs evaporative cooling in a two-stage process. Yeast cultures are placed in glass ampoules after having been mixed with a lyoprotectant. Primary drying is carried out using a centrifuge head connected to a standard <span class="hlt">freeze</span>-dryer. Once the centrifuge head is running, air is removed and evaporated liquid is captured in the <span class="hlt">freeze</span>-dryer. Centrifugation continues for 15 min and primary drying for a further 3 h. The ampoules are constricted using a glass blowing torch. They are then placed on the <span class="hlt">freeze</span>-dryer manifold for secondary drying under vacuum overnight, using phosphorus pentoxide as a desiccant. The ampoules are sealed and removed from the manifold by melting the constricted section. Although the process causes an initial large drop in viability, further losses after storage are minimal. Yeast strains have remained viable for more than 30 yr when stored using this method and sufficient cells are recovered to produce new working stocks. Although survival rates are strain specific, nearly all National Collection of Yeast Cultures strains covering most yeast genera, have been successfully stored with little or no detectable change in strain characteristics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27817036','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27817036"><span><span class="hlt">Freeze</span>-all cycle for all normal responders?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Roque, Matheus; Valle, Marcello; Guimarães, Fernando; Sampaio, Marcos; Geber, Selmo</p> <p>2017-02-01</p> <p>The purpose of this study is to evaluate the <span class="hlt">freeze</span>-all strategy in subgroups of normal responders, to assess whether this strategy is beneficial regardless of ovarian response, and to evaluate the possibility of implementing an individualized embryo transfer (iET) based on ovarian response. This was an observational, cohort study performed in a private IVF center. A total of 938 IVF cycles were included in this study. The patients were submitted to controlled ovarian stimulation (COS) with a gonadotropin-releasing hormone (GnRH) antagonist protocol and a cleavage-stage day 3 embryo transfer. We performed a comparison of outcomes between the fresh embryo transfer (n = 523) and the <span class="hlt">freeze</span>-all cycles (n = 415). The analysis was performed in two subgroups of patients based on the number of retrieved oocytes: Group 1 (4-9 oocytes) and Group 2 (10-15 oocytes). In Group 1 (4-9 retrieved oocytes), the implantation rates (IR) were 17.9 and 20.5% (P = 0.259) in the fresh and <span class="hlt">freeze</span>-all group, respectively; the ongoing pregnancy rates (OPR) were 31 and 33% (P = 0.577) in the fresh and <span class="hlt">freeze</span>-all group, respectively. In Group 2 (10-15 oocytes), the IR were 22.1 and 30.1% (P = 0.028) and the OPR were 34 and 47% (P = 0.021) in the fresh and <span class="hlt">freeze</span>-all groups, respectively. Although the <span class="hlt">freeze</span>-all policy may be related to better in vitro fertilization (IVF) outcomes in normal responders, these potential advantages decrease with worsening ovarian response. Patients with poorer ovarian response do not benefit from the <span class="hlt">freeze</span>-all strategy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017TCry...11.1059P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017TCry...11.1059P"><span>Response of seasonal soil <span class="hlt">freeze</span> depth to climate change across China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Peng, Xiaoqing; Zhang, Tingjun; Frauenfeld, Oliver W.; Wang, Kang; Cao, Bin; Zhong, Xinyue; Su, Hang; Mu, Cuicui</p> <p>2017-05-01</p> <p>The response of seasonal soil <span class="hlt">freeze</span> depth to climate change has repercussions for the surface energy and water balance, ecosystems, the carbon cycle, and soil nutrient exchange. Despite its importance, the response of soil <span class="hlt">freeze</span> depth to climate change is largely unknown. This study employs the Stefan solution and observations from 845 meteorological stations to investigate the response of variations in soil <span class="hlt">freeze</span> depth to climate change across China. Observations include daily air temperatures, daily soil temperatures at various depths, mean monthly gridded air temperatures, and the normalized difference vegetation index. Results show that soil <span class="hlt">freeze</span> depth decreased significantly at a rate of -0.18 ± 0.03 cm yr-1, resulting in a net decrease of 8.05 ± 1.5 cm over 1967-2012 across China. On the regional scale, soil <span class="hlt">freeze</span> depth decreases varied between 0.0 and 0.4 cm yr-1 in most parts of China during 1950-2009. By investigating potential climatic and environmental driving factors of soil <span class="hlt">freeze</span> depth variability, we find that mean annual air temperature and ground surface temperature, air thawing index, ground surface thawing index, and vegetation growth are all negatively associated with soil <span class="hlt">freeze</span> depth. Changes in snow depth are not correlated with soil <span class="hlt">freeze</span> depth. Air and ground surface <span class="hlt">freezing</span> indices are positively correlated with soil <span class="hlt">freeze</span> depth. Comparing these potential driving factors of soil <span class="hlt">freeze</span> depth, we find that <span class="hlt">freezing</span> index and vegetation growth are more strongly correlated with soil <span class="hlt">freeze</span> depth, while snow depth is not significant. We conclude that air temperature increases are responsible for the decrease in seasonal <span class="hlt">freeze</span> depth. These results are important for understanding the soil <span class="hlt">freeze</span>-thaw dynamics and the impacts of soil <span class="hlt">freeze</span> depth on ecosystem and hydrological process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29527684','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29527684"><span>Effects of <span class="hlt">freezing</span> conditions on quality changes in blueberries.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cao, Xuehui; Zhang, Fangfang; Zhao, Dongyu; Zhu, Danshi; Li, Jianrong</p> <p>2018-03-12</p> <p><span class="hlt">Freezing</span> preservation is one of the most effective methods used to maintain the flavour and nutritional value of fruit. This research studied the effects of different <span class="hlt">freezing</span> conditions, -20 °C, -40 °C, -80 °C, and immersion in liquid nitrogen, on quality changes of <span class="hlt">freeze</span>-thawed blueberries. The water distribution estimates of blueberries were measured based on low-field nuclear magnetic resonance (LF-NMR) analysis. The pectin content, drip loss, and fruit texture were also detected to evaluate quality changes in samples. The <span class="hlt">freezing</span> curves of blueberry showed super-cooling points at -20 °C and - 40 °C, whereas super-cooling points were not observed at -80 °C or in liquid nitrogen. After <span class="hlt">freeze</span>-thaw treatment, the relaxation time of the cell wall water (T 21 ), cytoplasm water and extracellular space (T 22 ), and vacuole water (T 23 ) were significantly shortened compared to fresh samples, which suggested a lower liquidity. Although the <span class="hlt">freezing</span> speed for samples immersed in liquid nitrogen was faster than other treatments, samples treated at -80 °C showed better quality regarding vacuole water holding, drip loss, and original pectin content retention. This study contributed to understanding how <span class="hlt">freezing</span> temperature affects the qualities of blueberries. The super-fast <span class="hlt">freezing</span> rate might injure fruit, and an appropriate <span class="hlt">freezing</span> rate could better preserve blueberries. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017E3SWC..2200078K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E3SWC..2200078K"><span>Air temperature <span class="hlt">gradient</span> in large industrial hall</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Karpuk, Michał; Pełech, Aleksander; Przydróżny, Edward; Walaszczyk, Juliusz; Szczęśniak, Sylwia</p> <p>2017-11-01</p> <p>In the rooms with dominant sensible heat load, volume airflow depends on many factors incl. pre-established temperature difference between exhaust and supply airflow. As the temperature difference is getting higher, airflow volume drops down, consequently, the cost of AHU is reduced. In high industrial halls with air exhaust grids located under the ceiling additional temperature <span class="hlt">gradient</span> above working zone should be taken into consideration. In this regard, experimental research of the <span class="hlt">vertical</span> air temperature <span class="hlt">gradient</span> in high industrial halls were carried out for the case of mixing ventilation system The paper presents the results of air temperature distribution measurements in high technological hall (mechanically ventilated) under significant sensible heat load conditions. The supply airflow was delivered to the hall with the help of the swirl diffusers while exhaust grids were located under the hall ceiling. Basing on the air temperature distribution measurements performed on the seven pre-established levels, air temperature <span class="hlt">gradient</span> in the area between 2.0 and 7.0 m above the floor was calculated and analysed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/48045','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/48045"><span>Spatial and temporal dynamics of disturbance interactions along an ecological <span class="hlt">gradient</span></span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Christopher D. O' Connor</p> <p>2013-01-01</p> <p>Interactions among site conditions, disturbance events, and climate determine the patterns of forest species recruitment and mortality across landscapes. Forests of the American Southwest have undergone significant changes over a century of altered disturbance regimes, human land uses, and changing environmental conditions. Along steep <span class="hlt">vertical</span> <span class="hlt">gradients</span> such as those...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29306082','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29306082"><span>Effect of <span class="hlt">freezing</span> conditions on β-Tricalcium Phosphate /Camphene scaffold with micro sized particles fabricated by <span class="hlt">freeze</span> casting.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Singh, Gurdev; Soundarapandian, S</p> <p>2018-03-01</p> <p>The long standing need of the implant manufacturing industries is to fabricate multi-matrix, customized porous scaffold as cost-effectively. In recent years, <span class="hlt">freeze</span> casting has shown greater opportunity in the fabrication of porous scaffolds (tricalcium phosphate, hydroxyapatite, bioglass, alumina, etc.) such as at ease and good control over pore size, porosity, a range of materials and economic feasibility. In particular, tricalcium phosphate (TCP) has proved as it possesses good biocompatible (osteoinduction, osteoconduction, etc.) and biodegradability hence beta-tricalcium phosphate (β-TCP, particle size of 10µm) was used as base material and camphene was used as a <span class="hlt">freezing</span> vehicle in this study. Both <span class="hlt">freezing</span> conditions such as constant <span class="hlt">freezing</span> temperature (CFT) and constant <span class="hlt">freezing</span> rate (CFR) were used for six different conditional samples (CFT: 30, 35 and 40vol% solid loading; similarly CFR: 30, 35 and 40vol% solid loading) to study and understand the effect of various properties (pore size, porosity and compressive strength) of the <span class="hlt">freeze</span>-cast porous scaffold. It was observed that the average size of the pore was varying linearly as from lower to higher when the solid loading was varying higher to lower. With the help of scanning electron micrographs (SEM), it was observed that the average size of pore during CFR (9.7/ 6.5/ 4.9µm) was comparatively higher than the process of CFT (6.0/ 4.8/ 2.6µm) with respect to the same solid loading (30/ 35/ 40vol%) conditions. From the Gas pycnometer analysis, it was found that the porosity in both <span class="hlt">freezing</span> conditions (CFT, CFR) were almost near values such as 32.8% and 28.5%. Further to be observed that with the increase in solid loading, the total porosity value has decreased due to the reduction in the concentration of the <span class="hlt">freezing</span> vehicle. Hence, the <span class="hlt">freezing</span> vehicle was found as responsible for the formation of appropriate size and orientation of pores during <span class="hlt">freeze</span> casting. The compressive strength (CS</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6672984','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/6672984"><span>Automated apparatus for producing <span class="hlt">gradient</span> gels</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Anderson, N.L.</p> <p>1983-11-10</p> <p>Apparatus for producing a <span class="hlt">gradient</span> gel which serves as a standard medium for a two-dimensional analysis of proteins, the gel having a density <span class="hlt">gradient</span> along its height formed by a variation in gel composition, with the apparatus including first and second pumping means each including a plurality of pumps on a common shaft and driven by a stepping motor capable of providing small incremental changes in pump outputs for the gel ingredients, the motors being controlled, by digital signals from a digital computer, a hollow form or cassette for receiving the gel composition, means for transferring the gel composition including a filler tube extending near the bottom of the cassette, adjustable horizontal and <span class="hlt">vertical</span> arms for automatically removing and relocating the filler tube in the next cassette, and a digital computer programmed to automatically control the stepping motors, arm movements, and associated sensing operations involving the filling operation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/865874','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/865874"><span>Automated apparatus for producing <span class="hlt">gradient</span> gels</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Anderson, Norman L.</p> <p>1986-01-01</p> <p>Apparatus for producing a <span class="hlt">gradient</span> gel which serves as a standard medium for a two-dimensional analysis of proteins, the gel having a density <span class="hlt">gradient</span> along its height formed by a variation in gel composition, with the apparatus including first and second pumping means each including a plurality of pumps on a common shaft and driven by a stepping motor capable of providing small incremental changes in pump outputs for the gel ingredients, the motors being controlled, by digital signals from a digital computer, a hollow form or cassette for receiving the gel composition, means for transferring the gel composition including a filler tube extending near the bottom of the cassette, adjustable horizontal and <span class="hlt">vertical</span> arms for automatically removing and relocating the filler tube in the next cassette, and a digital computer programmed to automatically control the stepping motors, arm movements, and associated sensing operations involving the filling operation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvA..96f2324Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvA..96f2324Y"><span>Experimental realization of self-guided quantum coherence <span class="hlt">freezing</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yu, Shang; Wang, Yi-Tao; Ke, Zhi-Jin; Liu, Wei; Zhang, Wen-Hao; Chen, Geng; Tang, Jian-Shun; Li, Chuan-Feng; Guo, Guang-Can</p> <p>2017-12-01</p> <p>Quantum coherence is the most essential characteristic of quantum physics, specifcially, when it is subject to the resource-theoretical framework, it is considered as the most fundamental resource for quantum techniques. Other quantum resources, e.g., entanglement, are all based on coherence. Therefore, it becomes urgently important to learn how to preserve coherence in quantum channels. The best preservation is coherence <span class="hlt">freezing</span>, which has been studied recently. However, in these studies, the <span class="hlt">freezing</span> condition is theoretically calculated, and there still lacks a practical way to achieve this <span class="hlt">freezing</span>; in addition the channels are usually fixed, but actually, there are also degrees of freedom that can be used to adapt the channels to quantum states. Here we develop a self-guided quantum coherence <span class="hlt">freezing</span> method, which can guide either the quantum channels (tunable-channel scheme with upgraded channels) or the initial state (fixed-channel scheme) to the coherence-<span class="hlt">freezing</span> zone from any starting estimate. Specifically, in the fixed-channel scheme, the final-iterative quantum states all satisfy the previously calculated <span class="hlt">freezing</span> condition. This coincidence demonstrates the validity of our method. Our work will be helpful for the better protection of quantum coherence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24852630','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24852630"><span>Identification of Arabidopsis mutants with altered <span class="hlt">freezing</span> tolerance.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Perea-Resa, Carlos; Salinas, Julio</p> <p>2014-01-01</p> <p>Low temperature is an important determinant in the configuration of natural plant communities and defines the range of distribution and growth of important crops. Some plants, including Arabidopsis, have evolved sophisticated adaptive mechanisms to tolerate low and <span class="hlt">freezing</span> temperatures. Central to this adaptation is the process of cold acclimation. By means of this process, many plants from temperate regions are able to develop or increase their <span class="hlt">freezing</span> tolerance in response to low, nonfreezing temperatures. The identification and characterization of factors involved in <span class="hlt">freezing</span> tolerance are crucial to understand the molecular mechanisms underlying the cold acclimation response and have a potential interest to improve crop tolerance to <span class="hlt">freezing</span> temperatures. Many genes implicated in cold acclimation have been identified in numerous plant species by using molecular approaches followed by reverse genetic analysis. Remarkably, however, direct genetic analyses have not been conveniently exploited in their capacity for identifying genes with pivotal roles in that adaptive response. In this chapter, we describe a protocol for evaluating the <span class="hlt">freezing</span> tolerance of both non-acclimated and cold-acclimated Arabidopsis plants. This protocol allows the accurate and simple screening of mutant collections for the identification of novel factors involved in <span class="hlt">freezing</span> tolerance and cold acclimation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AIPA....8e5226L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AIPA....8e5226L"><span>Morphology of supercooled droplets <span class="hlt">freezing</span> on solid surfaces</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>La, Shiren; Huang, Zhiting; Liu, Cong; Zhang, Xingyi</p> <p>2018-05-01</p> <p>Supercooled droplets <span class="hlt">freezing</span> on solid surfaces are ubiquitous in nature. This letter investigates the influences of droplet viscosity on <span class="hlt">freezing</span> velocity and frosting formation. Several experiments were conducted for three kinds of sessile droplets (water, silicone oil and oil) on two types of substrates (copper and iron) with different surface roughness at various temperatures. The results show that the water droplets exhibit obvious phase transition lines and their <span class="hlt">freezing</span> speeds increase when the temperature of substrates decreases. It is found that the <span class="hlt">freezing</span> speed is independent of the thermal conductivities of the substrates. Notably, the water droplets develop prominent bulges after <span class="hlt">freezing</span> and subsequently nucleate to frost. In contrast, the high viscosity oil and silicone oil do not manifest an obvious phase transition line. Besides, no bulges are observed in these two kinds of droplets, suggesting that these frosting forms are of different mechanisms compared with water droplets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28228353','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28228353"><span>Isochoric and isobaric <span class="hlt">freezing</span> of fish muscle.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Năstase, Gabriel; Lyu, Chenang; Ukpai, Gideon; Şerban, Alexandru; Rubinsky, Boris</p> <p>2017-04-01</p> <p>We have recently shown that, a living organism, which succumbs to <span class="hlt">freezing</span> to -4 °C in an isobaric thermodynamic system (constant atmospheric pressure), can survive <span class="hlt">freezing</span> to -4 °C in an isochoric thermodynamic system (constant volume). It is known that the mechanism of cell damage in an isobaric system is the <span class="hlt">freezing</span> caused increase in extracellular osmolality, and, the consequent cell dehydration. An explanation for the observed survival during isochoric <span class="hlt">freezing</span> is the thermodynamic modeling supported hypothesis that, in the isochoric frozen solution the extracellular osmolality is comparable to the cell intracellular osmolality. Therefore, cells in the isochoric frozen organism do not dehydrate, and the tissue maintains its morphological integrity. Comparing the histology of: a) fresh fish white muscle, b) fresh muscle frozen to -5 °C in an isobaric system and c) fresh muscle frozen to -5 °C I in an isochoric system, we find convincing evidence of the mechanism of cell dehydration during isobaric <span class="hlt">freezing</span>. In contrast, the muscle tissue frozen to -5 °C in an isochoric system appears morphologically identical to fresh tissue, with no evidence of dehydration. This is the first experimental evidence in support of the hypothesis that in isochoric <span class="hlt">freezing</span> there is no cellular dehydration and therefore the morphology of the frozen tissue remains intact. Copyright © 2017 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.2698K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.2698K"><span>Ambient in-situ immersion <span class="hlt">freezing</span> measurements - findings from the ZAMBIS 2014 field campaign for three ice nucleation techniques</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kohn, Monika; Atkinson, James D.; Lohmann, Ulrike; Kanji, Zamin A.</p> <p>2015-04-01</p> <p>To estimate the influence of clouds on the Earth's radiation budget, it is crucial to understand cloud formation processes in the atmosphere. A key process, which significantly affects cloud microphysical properties and the initiation of precipitation thus contributing to the hydrological cycle, is the prevailing type of ice nucleation mechanism. In mixed-phase clouds immersion <span class="hlt">freezing</span> is the dominant ice crystal forming mechanism, whereby ice nucleating particles (INP) first act as cloud condensation nuclei (CCN) and are activated to cloud droplets followed by <span class="hlt">freezing</span> upon supercooling. There are a number of experimental methods and techniques to investigate the ice nucleating ability in the immersion mode, however most techniques are offline for field sampling or only suitable for laboratory measurements. In-situ atmospheric studies are needed to understand the ice formation processes of 'real world' particles. Laboratory experiments simulate conditions of atmospheric processes like ageing or coating but are still idealized. Our method is able to measure ambient in-situ immersion <span class="hlt">freezing</span> on single immersed aerosol particles. The instrumental setup consists of the recently developed portable immersion mode cooling chamber (PIMCA) as a <span class="hlt">vertical</span> extension to the portable ice nucleation chamber (PINC, [1]), where the frozen fraction of activated aerosol particles are detected by the ice optical depolarization detector (IODE, [2]). Two additional immersion <span class="hlt">freezing</span> techniques based on a droplet <span class="hlt">freezing</span> array [3,4] are used to sample ambient aerosol particles either in a suspension (fraction larger ~0.6 μm) or on PM10-filters to compare different ice nucleation techniques. Here, we present ambient in-situ measurements at an urban forest site in Zurich, Switzerland held during the Zurich ambient immersion <span class="hlt">freezing</span> study (ZAMBIS) in spring 2014. We investigated the ice nucleating ability of natural atmospheric aerosol with the PIMCA/PINC immersion <span class="hlt">freezing</span> setup as</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GBioC..31.1420S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GBioC..31.1420S"><span>Stirring Up the Biological Pump: <span class="hlt">Vertical</span> Mixing and Carbon Export in the Southern Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stukel, Michael R.; Ducklow, Hugh W.</p> <p>2017-09-01</p> <p>The biological carbon pump (BCP) transports organic carbon from the surface to the ocean's interior via sinking particles, <span class="hlt">vertically</span> migrating organisms, and passive transport of organic matter by advection and diffusion. While many studies have quantified sinking particles, the magnitude of passive transport remains poorly constrained. In the Southern Ocean weak thermal stratification, strong <span class="hlt">vertical</span> <span class="hlt">gradients</span> in particulate organic matter, and weak <span class="hlt">vertical</span> nitrate <span class="hlt">gradients</span> suggest that passive transport from the euphotic zone may be particularly important. We compile data from seasonal time series at a coastal site near Palmer Station, annual regional cruises in the Western Antarctic Peninsula (WAP), cruises throughout the broader Southern Ocean, and SOCCOM (Southern Ocean Carbon and Climate Observations and Modeling) autonomous profiling floats to estimate spatial and temporal patterns in <span class="hlt">vertical</span> <span class="hlt">gradients</span> of nitrate, particulate nitrogen (PN), and dissolved organic carbon. Under a steady state approximation, the ratio of ∂PN/∂z to ∂NO3-/∂z suggests that passive transport of PN may be responsible for removing 46% (37%-58%) of the nitrate introduced into the surface ocean of the WAP (with dissolved organic matter contributing an additional 3-6%) and for 23% (19%-28%) of the BCP in the broader Southern Ocean. A simple model parameterized with in situ nitrate, PN, and primary production data suggested that passive transport was responsible for 54% of the magnitude of the BCP in the WAP. Our results highlight the potential importance of passive transport (by advection and diffusion) of organic matter in the Southern Ocean but should only be considered indicative of high passive transport (rather than conclusive evidence) due to our steady state assumptions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26247315','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26247315"><span><span class="hlt">Freeze</span>-dried dog sperm: Dynamics of DNA integrity.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Olaciregui, M; Luño, V; Gonzalez, N; De Blas, I; Gil, L</p> <p>2015-10-01</p> <p><span class="hlt">Freeze</span>-drying (FD) has been proposed as an alternative method to preserve spermatozoa. During the FD procedure, sperm DNA might become damaged by both <span class="hlt">freezing</span> and drying stresses caused by the endonucleases, the oxidative stress and the storage conditions. We examined the DNA integrity of dog sperm <span class="hlt">freeze</span>-dried with two kinds of chelating agents in FD buffers and storage at two different temperatures. Ejaculated sperm from four dogs were suspended in basic medium (10 mM Tris-HCl buffer+50 mM NaCl) supplemented with 50 mM EGTA or with 50 mM EDTA and then <span class="hlt">freeze</span>-dried. Sperm samples were stored at 4°C as room temperature, and the analysis of DNA damage was performed after a month and 5 months of storage using a Sperm Chromatin Dispersion test. We found four different sperm populations according to the size of the halos around the sperm head: (1) absent halo, (2) <6 μm, (3) 6-10 μm, (4) >10 μm. All of them coexisted in each <span class="hlt">freeze</span>-dried dog semen samples and differed significantly among different treatments. The highest percentage of spermatozoa with halo >10 μm was obtained when the semen samples were <span class="hlt">freeze</span>-dried in EDTA medium and stored at room temperature for five months. Results suggested that both, the kind of chelating agent as well as storage temperature and period, influenced DNA integrity of <span class="hlt">freeze</span>-dried dog sperm. Copyright © 2015 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018OptLE.105..188D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018OptLE.105..188D"><span>One-shot 3D scanning by combining sparse landmarks with dense <span class="hlt">gradient</span> information</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Di Martino, Matías; Flores, Jorge; Ferrari, José A.</p> <p>2018-06-01</p> <p>Scene understanding is one of the most challenging and popular problems in the field of robotics and computer vision and the estimation of 3D information is at the core of most of these applications. In order to retrieve the 3D structure of a test surface we propose a single shot approach that combines dense <span class="hlt">gradient</span> information with sparse absolute measurements. To that end, we designed a colored pattern that codes fine horizontal and <span class="hlt">vertical</span> fringes, with sparse corners landmarks. By measuring the deformation (bending) of horizontal and <span class="hlt">vertical</span> fringes, we are able to estimate surface local variations (i.e. its <span class="hlt">gradient</span> field). Then corner sparse landmarks are detected and matched to infer spare absolute information about the test surface height. Local <span class="hlt">gradient</span> information is combined with the sparse absolute values which work as anchors to guide the integration process. We show that this can be mathematically done in a very compact and intuitive way by properly defining a Poisson-like partial differential equation. Then we address in detail how the problem can be formulated in a discrete domain and how it can be practically solved by straight forward linear numerical solvers. Finally, validation experiment are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JOUC...16..831Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JOUC...16..831Y"><span>Optimization of protectant, salinity and <span class="hlt">freezing</span> condition for <span class="hlt">freeze</span>-drying preservation of Edwardsiella tarda</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yu, Yongxiang; Zhang, Zheng; Wang, Yingeng; Liao, Meijie; Li, Bin; Xue, Liangyi</p> <p>2017-10-01</p> <p>Novel preservation condition without ultra-low temperature is needed for the study of pathogen in marine fishes. <span class="hlt">Freeze</span>-drying is such a method usually used for preservation of terrigenous bacteria. However, studies using <span class="hlt">freeze</span>-drying method to preserving marine microorganisms remain very limited. In this study, we optimized the composition of protectants during the <span class="hlt">freeze</span>-drying of Edwardsiella tarda, a fish pathogen that causes systemic infection in marine fishes. We found that the optimal composition of protectant mixture contained trehalose (8.0%), skim milk (12.0%), sodium citrate (2.0%), serum (12.0%) and PVP (2.0%). Orthogonal and interaction analyses demonstrated the interaction between serum and skim milk or sodium citrate. The highest survival rate of E. tarda was observed when the concentration of NaCl was 10.0, 30.0 and between 5.0 and 10.0 g L-1 for preparing TSB medium, E. tarda suspension and protectant mixture, respectively. When E. tarda was frozen at -80°C or -40°C for 6 h, its survival rate was higher than that under other tested conditions. Under the optimized conditions, when the protectant mixture was used during <span class="hlt">freeze</span>-drying process, the survival rate (79.63%-82.30%) of E. tarda was significantly higher than that obtained using single protectant. Scanning electron microscopy (SEM) image indicated that E. tarda was embedded in thick matrix with detectable aggregation. In sum, the protectant mixture may be used as a novel cryoprotective additive for E. tarda.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.C33C1276R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.C33C1276R"><span>Elevation <span class="hlt">Gradients</span> and Climatic Consequences</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Redmond, K. T.</p> <p>2006-12-01</p> <p>Steep topography usually results in <span class="hlt">gradients</span> in surface meteorological elements. Sometimes these <span class="hlt">gradients</span> are extremely sharp. Frequent or persistent <span class="hlt">gradients</span> are expressed in climatic statistics as well. Most commonly, higher elevations are wetter and cooler than lower elevations. The magnitude of these climate <span class="hlt">gradients</span> vary both spatially and temporally, generally on smaller scales for the former and on a greater variety of scales for the latter. Orographic contributions to precipitation vary on hourly to annual scales, and temperature inversions of different durations can alter or reverse the <span class="hlt">vertical</span> temperature lapse rate normally found in the atmosphere. The presence of these factors affects the probability distributions of climate elements as a function of elevation. This leads in turn to consequences for ecology, resource management, and data. Orographic enhancement of Sierra precipitation varies by a factor of about three on seasonal time scales, and more on shorter scales. Particularly strong <span class="hlt">gradients</span> in temperature climate are observed along the California coast, resulting in large changes in long-term climatological probability distributions over quite short distances in elevation. These have significant implications for plant life. For specific noteworthy events, such as the California heat wave of July 2006, striking differences were seen over a horizontal distance of merely 2-3 km along the Big Sur Coast, related entirely to elevation. There is evidence of differential warming with elevation between California's Central Valley and the Sierra Nevada. As a practical matter, the three-dimensional correlation fields of weather and climate elements in topographically diverse regions, on differing time scales, have complex structure, but also have certain regularities. This makes quality control of weather and climate data sets in highly diverse topography much more challenging. Quality control decisions that do not properly take this correlation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/6700733','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/6700733"><span>Fish antifreeze protein and the <span class="hlt">freezing</span> and recrystallization of ice.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Knight, C A; DeVries, A L; Oolman, L D</p> <p></p> <p>Antifreeze glycopeptide and peptides from the blood of polar fishes prevent the growth of ice crystals in water at temperatures down to approximately 1 degree C below <span class="hlt">freezing</span> point, but do not appreciably influence the equilibrium <span class="hlt">freezing</span> point. This <span class="hlt">freezing</span> point hysteresis must be a disequilibrium effect, or it would violate Gibbs' phase rule, but the separate <span class="hlt">freezing</span> and melting points are experimentally very definite: ice neither melts nor <span class="hlt">freezes</span> perceptibly within the 'hysteresis gap', for periods of hours or days. We report here unusual crystal faces on ice crystals grown from solutions of very low concentrations of the anti-<span class="hlt">freeze</span> glycopeptides and peptides. This is a clue to the mechanism of <span class="hlt">freezing</span> inhibition, and it may be the basis of a simple, very sensitive test for antifreeze material. Very low concentrations of the antifreeze protein are also remarkably effective in preventing the recrystallization of ice.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.5117D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.5117D"><span>Particle-size dependence of immersion <span class="hlt">freezing</span>: Investigation of INUIT test aerosol particles with freely suspended water drops.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Diehl, Karoline; Debertshäuser, Michael; Eppers, Oliver; Jantsch, Evelyn; Mitra, Subir K.</p> <p>2014-05-01</p> <p>One goal of the research group INUIT (Ice Nuclei research UnIT) is to investigate the efficiencies of several test ice nuclei under comparable conditions but with different experimental techniques. In the present studies, two methods are used: the Mainz <span class="hlt">vertical</span> wind tunnel and an acoustic levitator placed inside a cold chamber. In both cases drops are freely levitated, either at their terminal velocity in the wind tunnel updraft or around the nodes of a standing ultrasonic wave in the acoustic levitator. Thus, heat transfer conditions are well approximated, and wall contact effects on <span class="hlt">freezing</span> as well as electrical charges of the drops are avoided. Drop radii are 370 μm and 1 mm, respectively. In the wind tunnel, drops are investigated at constant temperatures within a certain time period and the onset of <span class="hlt">freezing</span> is observed directly. In the acoustic levitator, the drop temperature decreases during the experiments and is measured by an in-situ calibrated Infrared thermometer. The onset of <span class="hlt">freezing</span> is indicated by a rapid rise of the drop surface temperature because of the release of latent heat. Investigated test ice nuclei are Snomax® as a proxy of biological particles and illite NX as well as K-feldspar as represents of mineral dust. The particle concentrations are 1 × 10-12 to 3 × 10-6 g Snomax® per drop and 5 × 10-9 to 5 × 10-5 g mineral dust per drop. <span class="hlt">Freezing</span> temperatures are between -2 and -18° C in case of Snomax® and between -14 and -26° C in case of mineral dust. The lower the particle masses per drop the lower are the <span class="hlt">freezing</span> temperatures. For similar particle concentrations in the drops, the median <span class="hlt">freezing</span> temperatures determined by the two techniques agree well within the measurement errors. With the knowledge of the specific particle surface area of the mineral dusts, the results are interpreted also in terms of particle surface area per drop. Results from the wind tunnel experiments which are performed at constant temperatures indicate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17416359','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17416359"><span>Mutagenic effect of <span class="hlt">freezing</span> on mitochondrial DNA of Saccharomyces cerevisiae.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stoycheva, T; Venkov, P; Tsvetkov, Ts</p> <p>2007-06-01</p> <p>Although suggested in some studies, the mutagenic effect of <span class="hlt">freezing</span> has not been proved by induction and isolation of mutants. Using a well-defined genetic model, we supply in this communication evidence for the mutagenic effect of <span class="hlt">freezing</span> on mitochondrial DNA (mtDNA) of the yeast Saccharomyces cerevisiae. The cooling for 2 h at +4 degrees C, followed by <span class="hlt">freezing</span> for 1 h at -10 degrees C and 16 h at -20 degrees C resulted in induction of respiratory mutations. The immediate <span class="hlt">freezing</span> in liquid nitrogen was without mutagenic effect. The study of the stepwise procedure showed that the induction of respiratory mutants takes place during the <span class="hlt">freezing</span> at -10 and -20 degrees C of cells pre-cooled at +4 degrees C. The genetic crosses of <span class="hlt">freeze</span>-induced mutants evidenced their mitochondrial rho- origin. The <span class="hlt">freeze</span>-induced rho- mutants are most likely free of simultaneous nuclear mutations. The extracellular presence of cryoprotectants did not prevent the mutagenic effect of <span class="hlt">freezing</span> while accumulation of cryoprotectors inside cells completely escaped mtDNA from cryodamage. Although the results obtained favor the notion that the mutagenic effect of <span class="hlt">freezing</span> on yeast mtDNA is due to formation and growth of intracellular ice crystals, other reasons, such as impairment of mtDNA replication or elevated levels of ROS production are discussed as possible explanations of the mutagenic effect of <span class="hlt">freezing</span>. It is concluded that: (i) <span class="hlt">freezing</span> can be used as a method for isolation of mitochondrial mutants in S. cerevisiae and (ii) given the substantial development in cryopreservation of cells and tissues, special precautions should be made to avoid mtDNA damage during the cryopreservation procedures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16844837','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16844837"><span>Natural genetic variation of <span class="hlt">freezing</span> tolerance in Arabidopsis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hannah, Matthew A; Wiese, Dana; Freund, Susanne; Fiehn, Oliver; Heyer, Arnd G; Hincha, Dirk K</p> <p>2006-09-01</p> <p>Low temperature is a primary determinant of plant growth and survival. Using accessions of Arabidopsis (Arabidopsis thaliana) originating from Scandinavia to the Cape Verde Islands, we show that <span class="hlt">freezing</span> tolerance of natural accessions correlates with habitat winter temperatures, identifying low temperature as an important selective pressure for Arabidopsis. Combined metabolite and transcript profiling show that during cold exposure, global changes of transcripts, but not of metabolites, correlate with the ability of Arabidopsis to cold acclimate. There are, however, metabolites and transcripts, including several transcription factors, that correlate with <span class="hlt">freezing</span> tolerance, indicating regulatory pathways that may be of primary importance for this trait. These data identify that enhanced <span class="hlt">freezing</span> tolerance is associated with the down-regulation of photosynthesis and hormonal responses and the induction of flavonoid metabolism, provide evidence for naturally increased nonacclimated <span class="hlt">freezing</span> tolerance due to the constitutive activation of the C-repeat binding factors pathway, and identify candidate transcriptional regulators that correlate with <span class="hlt">freezing</span> tolerance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26001487','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26001487"><span>The Impact of <span class="hlt">Freeze</span>-Thaw Cycles on Epinephrine.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Beasley, Heather; Ng, Pearlly; Wheeler, Albert; Smith, William R; McIntosh, Scott E</p> <p>2015-12-01</p> <p>Epinephrine is the first-line medical treatment for anaphylaxis, a life-threatening allergic syndrome. To treat anaphylaxis, backcountry recreationalists and guides commonly carry epinephrine autoinjectors. Epinephrine may be exposed to cold temperatures and <span class="hlt">freezing</span> during expeditions. An epinephrine solution must contain 90% to 115% of the labeled epinephrine amount to meet United States Pharmacopeia standards. The purpose of this study was to determine whether <span class="hlt">freeze</span>-thaw cycles alter epinephrine concentrations in autoinjectors labeled to contain 1.0 mg/mL epinephrine. A further objective was to determine whether samples continued to meet United States Pharmacopeia concentration standards after <span class="hlt">freeze</span>-thaw cycles. Epinephrine from 6 autoinjectors was extracted and divided into experimental and control samples. The experimental samples underwent 7 consecutive 12-hour <span class="hlt">freeze</span> cycles followed by 7 12-hour thaw cycles. The control samples remained at an average temperature of 23.1°C for the duration of the study. After the seventh thaw cycle, epinephrine concentrations were measured using a high-performance liquid chromatography assay with mass spectrometry detection. The mean epinephrine concentration of the <span class="hlt">freeze</span>-thaw samples demonstrated a statistically significant increase compared with the control samples: 1.07 mg/mL (SD ± 8.78; 95% CI, 1.04 to 1.11) versus 0.96 mg/mL (SD ± 6.81; 95% CI, 0.94 to 0.99), respectively. The maximal mean epinephrine concentration in the experimental <span class="hlt">freeze</span>-thaw group was 1.12 mg/mL, which still fell within the range of United States Pharmacopeia standards for injectables (0.90 to 1.15 mg/mL). Although every attempt should be made to prevent <span class="hlt">freezing</span> of autoinjectors, this preliminary study demonstrates that epinephrine concentrations remain within 90% to 115% of 1.0 mg/mL after multiple <span class="hlt">freeze</span>-thaw cycles. Copyright © 2015 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18708337','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18708337"><span>Sapwood temperature <span class="hlt">gradients</span> between lower stems and the crown do not influence estimates of stand-level stem CO(2) efflux.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bowman, William P; Turnbull, Matthew H; Tissue, David T; Whitehead, David; Griffin, Kevin L</p> <p>2008-10-01</p> <p>Temperature plays a critical role in the regulation of respiration rates and is often used to scale measurements of respiration to the stand-level and calculate annual respiratory fluxes. Previous studies have indicated that failure to consider temperature <span class="hlt">gradients</span> between sun-exposed stems and branches in the crown and shaded lower stems may result in errors when deriving stand-level estimates of stem CO(2) efflux. We measured <span class="hlt">vertical</span> <span class="hlt">gradients</span> in sapwood temperature in a mature lowland podocarp rain forest in New Zealand to: (1) estimate the effects of within-stem temperature variation on the <span class="hlt">vertical</span> distribution of stem CO(2) efflux; and (2) use these findings to estimate stand-level stem CO(2) efflux for this forest. Large within-stem <span class="hlt">gradients</span> in sapwood temperature (1.6 +/- 0.1 to 6.0 +/- 0.5 degrees C) were observed. However, these <span class="hlt">gradients</span> did not significantly influence the stand-level estimate of stem CO(2) efflux in this forest (536 +/- 42 mol CO(2) ha(-1) day(-1)) or the <span class="hlt">vertical</span> distribution of stem CO(2) efflux, because of the opposing effects of daytime warming and nighttime cooling on CO(2) efflux in the canopy, and the small fraction of the woody biomass in the crowns of forest trees. Our findings suggest that detailed measurements of within-stand temperature <span class="hlt">gradients</span> are unlikely to greatly improve the accuracy of tree- or stand-level estimates of stem CO(2) efflux.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25252645','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25252645"><span>Inactivation of Kudoa septempunctata in olive flounder meat by liquid <span class="hlt">freezing</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ohnishi, Takahiro; Akuzawa, Sayuri; Furusawa, Hiroko; Yoshinari, Tomoya; Kamata, Yoichi; Sugita-Konishi, Yoshiko</p> <p>2014-01-01</p> <p>Kudoa septempunctata in olive flounder meat was inactivated using 3 distinct <span class="hlt">freezing</span> methods:liquid <span class="hlt">freezing</span> for 5 min, air blast <span class="hlt">freezing</span> at -30℃ for 5 h, and -80℃ for 1 h. The fracture curve of olive flounder meat subjected to liquid <span class="hlt">freezing</span> resembled that of meat stored at 4℃, indicating that the structure of olive flounder muscle was well preserved. In contrast, air blast <span class="hlt">freezing</span> induced the disappearance of the fracture point in the fracture curve, indicating that there was deterioration in the meat quality. Liquid <span class="hlt">freezing</span> preserved the transparency of olive flounder meat to the same degree as that of meat stored at 4°C. However, air blast <span class="hlt">freezing</span> induced meat cloudiness. These results indicate that liquid <span class="hlt">freezing</span> can be used for K. septempunctata inactivation without affecting the meat quality.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24377325','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24377325"><span>Colloid-facilitated mobilization of metals by <span class="hlt">freeze</span>-thaw cycles.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mohanty, Sanjay K; Saiers, James E; Ryan, Joseph N</p> <p>2014-01-21</p> <p>The potential of <span class="hlt">freeze</span>-thaw cycles to release colloids and colloid-associated contaminants into water is unknown. We examined the effect of <span class="hlt">freeze</span>-thaw cycles on the mobilization of cesium and strontium in association with colloids in intact cores of a fractured soil, where preferential flow paths are prevalent. Two intact cores were contaminated with cesium and strontium. To mobilize colloids and metal cations sequestered in the soil cores, each core was subjected to 10 intermittent wetting events separated by 66 h pauses. During the first five pauses, the cores were dried at room temperature, and during last five pauses, the cores were subjected to 42 h of <span class="hlt">freezing</span> followed by 24 h of thawing. In comparison to drying, <span class="hlt">freeze</span>-thaw cycles created additional preferential flow paths through which colloids, cesium, and strontium were mobilized. The wetting events following <span class="hlt">freeze</span>-thaw intervals mobilized about twice as many colloids as wetting events following drying at room temperature. Successive wetting events following 66 h of drying mobilized similar amounts of colloids; in contrast, successive wetting events after 66 h of <span class="hlt">freeze</span>-thaw intervals mobilized greater amounts of colloids than the previous one. Drying and <span class="hlt">freeze</span>-thaw treatments, respectively, increased and decreased the dissolved cesium and strontium, but both treatments increased the colloidal cesium and strontium. Overall, the <span class="hlt">freeze</span>-thaw cycles increased the mobilization of metal contaminants primarily in association with colloids through preferential flow paths. These findings suggest that the mobilization of colloid and colloid-associated contaminants could increase when temperature variations occur around the <span class="hlt">freezing</span> point of water. Thus, climate extremes have the potential to mobilize contaminants that have been sequestered in the vadose zone for decades.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150022458','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150022458"><span>Determination <span class="hlt">Gradients</span> of the Earth's Magnetic Field from the Measurements of the Satellites and Inversion of the Kursk Magnetic Anomaly</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Karoly, Kis; Taylor, Patrick T.; Geza, Wittmann</p> <p>2014-01-01</p> <p>We computed magnetic field <span class="hlt">gradients</span> at satellite altitude, over Europe with emphasis on the Kursk Magnetic Anomaly (KMA). They were calculated using the CHAMP satellite total magnetic anomalies. Our computations were done to determine how the magnetic anomaly data from the new ESA/Swarm satellites could be utilized to determine the structure of the magnetization of the Earths crust, especially in the region of the KMA. Since the ten years of 2 CHAMP data could be used to simulate the Swarm data. An initial East magnetic anomaly <span class="hlt">gradient</span> map of Europe was computed and subsequently the North, East and <span class="hlt">Vertical</span> magnetic <span class="hlt">gradients</span> for the KMA region were calculated. The <span class="hlt">vertical</span> <span class="hlt">gradient</span> of the KMA was determined using Hilbert transforms. Inversion of the total KMA was derived using Simplex and Simulated Annealing algorithms. Our resulting inversion depth model is a horizontal quadrangle with upper 300-329 km and lower 331-339 km boundaries.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011NIMPA.652..174S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011NIMPA.652..174S"><span>Hierarchical microstructures in CZT</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sundaram, S. K.; Henager, C. H.; Edwards, D. J.; Schemer-Kohrn, A. L.; Bliss, M.; Riley, B. R.; Toloczko, M. B.; Lynn, K. G.</p> <p>2011-10-01</p> <p>Advanced characterization tools, such as electron backscatter diffraction and transmitted IR microscopy, are being applied to study critical microstructural features and orientation relations in as-grown CZT crystals to aid in understanding the relation between structure and properties in radiation detectors. Even carefully prepared single crystals of CZT contain regions of slight misorientation, Te-particles, and dislocation networks that must be understood for more accurate models of detector response. This paper describes initial research at PNNL into the hierarchy of microstructures observed in CZT grown via the <span class="hlt">vertical</span> <span class="hlt">gradient</span> <span class="hlt">freeze</span> or <span class="hlt">vertical</span> Bridgman method at PNNL and WSU.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA12350.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA12350.html"><span><span class="hlt">Freezing</span> WISE Hydrogen</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2009-11-12</p> <p>A scaffolding structure built around NASA Wide-field Infrared Survey Explorer allows engineers to <span class="hlt">freeze</span> its hydrogen coolant. The WISE infrared instrument is kept extremely cold by a bottle-like tank filled with frozen hydrogen, called the cryostat.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/665157-freeze-thaw-durability-concrete-ice-formation-process-pores','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/665157-freeze-thaw-durability-concrete-ice-formation-process-pores"><span><span class="hlt">Freeze</span>-thaw durability of concrete: Ice formation process in pores</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Cai, H.; Liu, X.</p> <p>1998-09-01</p> <p><span class="hlt">Freeze</span>-thaw durability of concrete is of great importance to hydraulic structures in cold areas. Study of ice formation process in concrete pores is necessary to evaluate the damages in concrete caused by <span class="hlt">freezing</span>. In this paper, <span class="hlt">freezing</span> of pore solution in concrete exposed to a <span class="hlt">freeze</span>-thaw cycle is studied by following the change of concrete electrical conductivity with <span class="hlt">freezing</span> temperatures. Concretes were subjected to <span class="hlt">freeze</span>-thaw cycles with temperature varying between {minus}0 C and {minus}20 C. In the <span class="hlt">freezing</span> process, the changing rate of concrete electrical conductivity obviously decreases at about {minus}10 C, indicating that more pore solution in concrete freezesmore » above {minus}10 C than below {minus}10C. According to Powers` static hydraulic pressure hypothesis, it is thought that frost damage mainly occurs between 0 C and {minus}100 C. To ordinary concrete, frost damages below {minus}10 C are negligible.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790011515','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790011515"><span>Mechanisms of deterioration of nutrients. [improved quality of <span class="hlt">freeze</span>-dried foods</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Karel, M.; Flink, J. M.</p> <p>1978-01-01</p> <p>Methods for improving the quality of <span class="hlt">freeze</span>-dried foods were investigated. Areas discussed include: (1) microstructure of <span class="hlt">freeze</span>-dried systems, (2) structural changes in <span class="hlt">freeze</span>-dried systems, (3) artificial food matrices, and (4) osmotic preconcentration to yield improved <span class="hlt">freeze</span>-dried products.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1247322-water-freezing-ice-melting','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1247322-water-freezing-ice-melting"><span>Water <span class="hlt">freezing</span> and ice melting</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Malolepsza, Edyta; Keyes, Tom</p> <p>2015-10-12</p> <p>The generalized replica exchange method (gREM) is designed to sample states with coexisting phases and thereby to describe strong first order phase transitions. The isobaric MD version of the gREM is presented and applied to <span class="hlt">freezing</span> of liquid water, and melting of hexagonal and cubic ice. It is confirmed that coexisting states are well sampled. The statistical temperature as a function of enthalpy, T S(H), is obtained. Hysteresis between <span class="hlt">freezing</span> and melting is observed and discussed. The entropic analysis of phase transitions is applied and equilibrium transition temperatures, latent heats, and surface tensions are obtained for hexagonal ice↔liquid and cubicmore » ice↔liquid, with excellent agreement with published values. A new method is given to assign water molecules among various symmetry types. As a result, pathways for water <span class="hlt">freezing</span>, ultimately leading to hexagonal ice, are found to contain intermediate layered structures built from hexagonal and cubic ice.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5459058','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5459058"><span>Fabrication Processes to Generate Concentration <span class="hlt">Gradients</span> in Polymer Solar Cell Active Layers</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Inaba, Shusei; Vohra, Varun</p> <p>2017-01-01</p> <p>Polymer solar cells (PSCs) are considered as one of the most promising low-cost alternatives for renewable energy production with devices now reaching power conversion efficiencies (PCEs) above the milestone value of 10%. These enhanced performances were achieved by developing new electron-donor (ED) and electron-acceptor (EA) materials as well as finding the adequate morphologies in either bulk heterojunction or sequentially deposited active layers. In particular, producing adequate <span class="hlt">vertical</span> concentration <span class="hlt">gradients</span> with higher concentrations of ED and EA close to the anode and cathode, respectively, results in an improved charge collection and consequently higher photovoltaic parameters such as the fill factor. In this review, we relate processes to generate active layers with ED–EA <span class="hlt">vertical</span> concentration <span class="hlt">gradients</span>. After summarizing the formation of such concentration <span class="hlt">gradients</span> in single layer active layers through processes such as annealing or additives, we will verify that sequential deposition of multilayered active layers can be an efficient approach to remarkably increase the fill factor and PCE of PSCs. In fact, applying this challenging approach to fabricate inverted architecture PSCs has the potential to generate low-cost, high efficiency and stable devices, which may revolutionize worldwide energy demand and/or help develop next generation devices such as semi-transparent photovoltaic windows. PMID:28772878</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28772878','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28772878"><span>Fabrication Processes to Generate Concentration <span class="hlt">Gradients</span> in Polymer Solar Cell Active Layers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Inaba, Shusei; Vohra, Varun</p> <p>2017-05-09</p> <p>Polymer solar cells (PSCs) are considered as one of the most promising low-cost alternatives for renewable energy production with devices now reaching power conversion efficiencies (PCEs) above the milestone value of 10%. These enhanced performances were achieved by developing new electron-donor (ED) and electron-acceptor (EA) materials as well as finding the adequate morphologies in either bulk heterojunction or sequentially deposited active layers. In particular, producing adequate <span class="hlt">vertical</span> concentration <span class="hlt">gradients</span> with higher concentrations of ED and EA close to the anode and cathode, respectively, results in an improved charge collection and consequently higher photovoltaic parameters such as the fill factor. In this review, we relate processes to generate active layers with ED-EA <span class="hlt">vertical</span> concentration <span class="hlt">gradients</span>. After summarizing the formation of such concentration <span class="hlt">gradients</span> in single layer active layers through processes such as annealing or additives, we will verify that sequential deposition of multilayered active layers can be an efficient approach to remarkably increase the fill factor and PCE of PSCs. In fact, applying this challenging approach to fabricate inverted architecture PSCs has the potential to generate low-cost, high efficiency and stable devices, which may revolutionize worldwide energy demand and/or help develop next generation devices such as semi-transparent photovoltaic windows.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15032301','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15032301"><span>Design of <span class="hlt">freeze</span>-drying processes for pharmaceuticals: practical advice.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tang, Xiaolin; Pikal, Michael J</p> <p>2004-02-01</p> <p>Design of <span class="hlt">freeze</span>-drying processes is often approached with a "trial and error" experimental plan or, worse yet, the protocol used in the first laboratory run is adopted without further attempts at optimization. Consequently, commercial <span class="hlt">freeze</span>-drying processes are often neither robust nor efficient. It is our thesis that design of an "optimized" <span class="hlt">freeze</span>-drying process is not particularly difficult for most products, as long as some simple rules based on well-accepted scientific principles are followed. It is the purpose of this review to discuss the scientific foundations of the <span class="hlt">freeze</span>-drying process design and then to consolidate these principles into a set of guidelines for rational process design and optimization. General advice is given concerning common stability issues with proteins, but unusual and difficult stability issues are beyond the scope of this review. Control of ice nucleation and crystallization during the <span class="hlt">freezing</span> step is discussed, and the impact of <span class="hlt">freezing</span> on the rest of the process and final product quality is reviewed. Representative <span class="hlt">freezing</span> protocols are presented. The significance of the collapse temperature and the thermal transition, denoted Tg', are discussed, and procedures for the selection of the "target product temperature" for primary drying are presented. Furthermore, guidelines are given for selection of the optimal shelf temperature and chamber pressure settings required to achieve the target product temperature without thermal and/or mass transfer overload of the <span class="hlt">freeze</span> dryer. Finally, guidelines and "rules" for optimization of secondary drying and representative secondary drying protocols are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001JGR...10611691M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001JGR...10611691M"><span>A laboratory study of mean flow generation in rotating fluids by Reynolds stress <span class="hlt">gradients</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McGuinness, D. S.; Boyer, D. L.; Fernando, H. J. S.</p> <p>2001-06-01</p> <p>Laboratory experiments were conducted that demonstrate that a mean azimuthal flow can be produced by introducing Reynolds stress <span class="hlt">gradients</span> to a rotating fluid with zero initial mean flow. This mechanism may play a role in the generation of mean currents in coastal regions. The experiments entail the establishment of turbulence in a thin annular-shaped region centered within a cylindrical test cell through the use of a <span class="hlt">vertically</span> oscillating grid. This region rests in a horizontal plane perpendicular to the <span class="hlt">vertical</span> axis of the tank, and the entire system is placed on a turntable to simulate background rotation. Flow visualization techniques are used to depict qualitative features of the resulting flow field. Measurements of the mean and turbulent velocity fields are performed using a two-component laser-Doppler velocimeter. The results show how rectified currents (mean flows) can be generated via Reynolds stress <span class="hlt">gradients</span> induced by periodic forcing of the grid. In the absence of background rotation, rectified flow is observed in the radial and <span class="hlt">vertical</span> directions only. The presence of background rotation tends to organize these motions in that the flow tends to move parallel to the turbulent source, i.e., in the azimuthal direction, with the source (strong turbulence) located to the right, facing downstream. The influence of rotation on the Reynolds stresses and their <span class="hlt">gradients</span> as well as on the ensuing mean flow is evaluated, and the observations are examined by considering individual contributions of the terms in the Reynolds-averaged momentum equations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27203090','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27203090"><span>Cost-Effectiveness of the <span class="hlt">Freeze</span>-All Policy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Roque, Matheus; Valle, Marcello; Guimarães, Fernando; Sampaio, Marcos; Geber, Selmo</p> <p>2015-08-01</p> <p>To evaluate the cost-effectiveness of <span class="hlt">freeze</span>-all cycles when compared to fresh embryo transfer. This was an observational study with a cost-effectiveness analysis. The analysis consisted of 530 intracytoplasmic sperm injection (ICSI) cycles in a private center in Brazil between January 2012 and December 2013. A total of 530 intracytoplasmic sperm injection (ICSI) cycles - 351 fresh embryo transfers and 179 <span class="hlt">freeze</span>-all cycles - with a gonadotropin-releasing hormone (GnRH) antagonist protocol and day 3 embryo transfers. The pregnancy rate was 31.1% in the fresh group and 39.7% in the <span class="hlt">freeze</span>-all group. We performed two scenario analyses for costs. In scenario 1, we included those costs associated with the ICSI cycle (monitoring during controlled ovarian stimulation [COS], oocyte retrieval, embryo transfer, IVF laboratory, and medical costs), embryo cryopreservation of supernumerary embryos, hormone measurements during COS and endometrial priming, medication use (during COS, endometrial priming, and luteal phase support), ultrasound scan for frozen- thawed embryo transfer (FET), obstetric ultrasounds, and miscarriage. The total cost (in USD) per pregnancy was statistically lower in the <span class="hlt">freeze</span>-all cycles (19,156.73 ± 1,732.99) when compared to the fresh cycles (23,059.72 ± 2,347.02). Even in Scenario 2, when charging all of the patients in the <span class="hlt">freeze</span>-all group for cryopreservation (regardless of supernumerary embryos) and for FET, the fresh cycles had a statistically significant increase in treatment costs per ongoing pregnancy. The results presented in this study suggest that the <span class="hlt">freeze</span>-all policy is a cost-effective strategy when compared to fresh embryo transfer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApJ...811...17L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApJ...811...17L"><span>Cooling Requirements for the <span class="hlt">Vertical</span> Shear Instability in Protoplanetary Disks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lin, Min-Kai; Youdin, Andrew N.</p> <p>2015-09-01</p> <p>The <span class="hlt">vertical</span> shear instability (VSI) offers a potential hydrodynamic mechanism for angular momentum transport in protoplanetary disks (PPDs). The VSI is driven by a weak <span class="hlt">vertical</span> <span class="hlt">gradient</span> in the disk’s orbital motion, but must overcome <span class="hlt">vertical</span> buoyancy, a strongly stabilizing influence in cold disks, where heating is dominated by external irradiation. Rapid radiative cooling reduces the effective buoyancy and allows the VSI to operate. We quantify the cooling timescale tc needed for efficient VSI growth, through a linear analysis of the VSI with cooling in <span class="hlt">vertically</span> global, radially local disk models. We find the VSI is most vigorous for rapid cooling with {t}{{c}}\\lt {{{Ω }}}{{K}}-1h| q| /(γ -1) in terms of the Keplerian orbital frequency, {{{Ω }}}{{K}}, the disk’s aspect-ratio, h\\ll 1, the radial power-law temperature <span class="hlt">gradient</span>, q, and the adiabatic index, γ. For longer tc, the VSI is much less effective because growth slows and shifts to smaller length scales, which are more prone to viscous or turbulent decay. We apply our results to PPD models where tc is determined by the opacity of dust grains. We find that the VSI is most effective at intermediate radii, from ∼5 to ∼50 AU with a characteristic growth time of ∼30 local orbital periods. Growth is suppressed by long cooling times both in the opaque inner disk and the optically thin outer disk. Reducing the dust opacity by a factor of 10 increases cooling times enough to quench the VSI at all disk radii. Thus the formation of solid protoplanets, a sink for dust grains, can impede the VSI.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3968094','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3968094"><span>Metabolic Changes in Avena sativa Crowns Recovering from <span class="hlt">Freezing</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Henson, Cynthia A.; Duke, Stanley H.; Livingston, David P.</p> <p>2014-01-01</p> <p>Extensive research has been conducted on cold acclimation and <span class="hlt">freezing</span> tolerance of fall-sown cereal plants due to their economic importance; however, little has been reported on the biochemical changes occurring over time after the <span class="hlt">freezing</span> conditions are replaced by conditions favorable for recovery and growth such as would occur during spring. In this study, GC-MS was used to detect metabolic changes in the overwintering crown tissue of oat (Avena sativa L.) during a fourteen day time-course after <span class="hlt">freezing</span>. Metabolomic analysis revealed increases in most amino acids, particularly proline, 5-oxoproline and arginine, which increased greatly in crowns that were frozen compared to controls and correlated very significantly with days after <span class="hlt">freezing</span>. In contrast, sugar and sugar related metabolites were little changed by <span class="hlt">freezing</span>, except sucrose and fructose which decreased dramatically. In frozen tissue all TCA cycle metabolites, especially citrate and malate, decreased in relation to unfrozen tissue. Alterations in some amino acid pools after <span class="hlt">freezing</span> were similar to those observed in cold acclimation whereas most changes in sugar pools after <span class="hlt">freezing</span> were not. These similarities and differences suggest that there are common as well as unique genetic mechanisms between these two environmental conditions that are crucial to the winter survival of plants. PMID:24675792</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA118862','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA118862"><span>Applications of Simulator <span class="hlt">Freeze</span> to Carrier Glideslope Tracking Instruction.</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1982-07-01</p> <p>Showing Datum Bars and Meatball . .. .. .. ... .. ... .... 19 4 <span class="hlt">Freezes</span> Per Trial Averaged Across <span class="hlt">Freeze</span> Conditions and Across 4-Trial Blocks of Training...algorithm linearly increased the criterion in meatball units from 1.0 at 6000 feet from the ramp to 1.5 at the ramp. "<span class="hlt">Freezes</span>" did not occur beyond 6000</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhDT........21N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhDT........21N"><span>Silicon-based Porous Ceramics via <span class="hlt">Freeze</span> Casting of Preceramic Polymers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Naviroj, Maninpat</p> <p></p> <p><span class="hlt">Freeze</span> casting is a technique for processing porous materials that has drawn significant attention for its effectiveness in producing a variety of tailorable pore structures for ceramics, metals, and polymers. With <span class="hlt">freeze</span> casting, pores are generated based on a solidification process where ice crystals act as a sacrificial template which can eventually be sublimated to create pores. While the majority of <span class="hlt">freeze</span>-casting studies have been performed using conventional ceramic suspensions, this work explores an alternative processing route by <span class="hlt">freeze</span> casting with preceramic polymer solutions. Significant differences exist between <span class="hlt">freeze</span> casting of a particulate suspension and a polymeric solution. These changes affect the processing method, solidification behavior, and pore structure, thereby introducing new challenges and possibilities for the <span class="hlt">freeze</span>-casting technique. The first part of this study explored the processing requirements involved with <span class="hlt">freeze</span> casting of preceramic polymers, along with methods to control the resulting pore structure. Solvent choice, <span class="hlt">freezing</span> front velocity, and polymer concentration were used as processing variables to manipulate the pore structures. A total of seven organic solvents were <span class="hlt">freeze</span> cast with a polymethylsiloxane preceramic polymer to produce ceramics with isotropic, dendritic, prismatic, and lamellar pore morphologies. Changes in <span class="hlt">freezing</span> front velocity and polymer concentration were shown to influence pore size, shape, and connectivity. Differences between suspension- and solution-based samples <span class="hlt">freeze</span> cast under equivalent conditions were also investigated. Certain solidification microstructures were strongly affected by the presence of suspended particles, creating differences between pore structures generated from the same solvents. Additionally, processing of solution-based samples were found to be the more facile technique. Compressive strength and water permeability of dendritic and lamellar structures were analyzed to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22458412-freeze-dark-matter-displaced-signatures-colliders','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22458412-freeze-dark-matter-displaced-signatures-colliders"><span><span class="hlt">Freeze</span>-In dark matter with displaced signatures at colliders</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Co, Raymond T.; D’Eramo, Francesco; Hall, Lawrence J.</p> <p>2015-12-11</p> <p>Dark matter, X, may be generated by new physics at the TeV scale during an early matter-dominated (MD) era that ends at temperature T{sub R}≪ TeV. Compared to the conventional radiation-dominated (RD) results, yields from both <span class="hlt">Freeze</span>-Out and <span class="hlt">Freeze</span>-In processes are greatly suppressed by dilution from entropy production, making <span class="hlt">Freeze</span>-Out less plausible while allowing successful <span class="hlt">Freeze</span>-In with a much larger coupling strength. <span class="hlt">Freeze</span>-In is typically dominated by the decay of a particle B of the thermal bath, B→X. For a large fraction of the relevant cosmological parameter space, the decay rate required to produce the observed dark matter abundance leadsmore » to displaced signals at LHC and future colliders, for any m{sub X} in the range keV« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol8/pdf/CFR-2010-title7-vol8-sec929-11.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol8/pdf/CFR-2010-title7-vol8-sec929-11.pdf"><span>7 CFR 929.11 - To can, <span class="hlt">freeze</span>, or dehydrate.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... 7 Agriculture 8 2010-01-01 2010-01-01 false To can, <span class="hlt">freeze</span>, or dehydrate. 929.11 Section 929.11... LONG ISLAND IN THE STATE OF NEW YORK Order Regulating Handling Definitions § 929.11 To can, <span class="hlt">freeze</span>, or dehydrate. To can, <span class="hlt">freeze</span>, or dehydrate means to convert cranberries into canned, frozen, or dehydrated...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A13A2038R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A13A2038R"><span>Immersion <span class="hlt">freezing</span> of ambient dust using WISDOM setup</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rudich, Y.; Reicher, N.</p> <p>2017-12-01</p> <p>A small subset of the atmospheric particles has the ability to induce ice formation. Among them are mineral dust particles that originate from arid regions. Mineral dust particles are internally mixed with various types of minerals such as kaolinite and illite from the clay minerals, quartz and feldspar. The mineral composition of the dust particles determine their <span class="hlt">freezing</span> efficiency. Much attention was given to the clay group, as they are the most common minerals transported in the atmosphere. Recently, much focus has been directed to the feldspars, since its ice efficiency is higher at warmer temperatures, and as such is may dominate <span class="hlt">freezing</span> in mixed phase clouds. Moreover, it was found that samples that contained higher content of feldspar had higher nucleation activity. In this study, we examine the immersion <span class="hlt">freezing</span> of ambient dust particles that were collected in Rehovot, Israel (31.9N, 34.8E about 80m AMSL), during dust storms from the Sahara and the Syrian deserts. The size-segregated dust particles were collected on cyclopore polycarbonate filters using a Micro-orifice Uniform deposit Impactor (MOUDI). <span class="hlt">Freezing</span> experiments were done using the WeIzmann Supercooled Droplets Observation on Microarray set (WISDOM). The particles were extracted from the filters by sonication and subsequently immersed in 100μm droplets that were cooled in a rate of 1°CPM to -37°C (homogenous <span class="hlt">freezing</span> threshold). Investigation of the particles mineralogy was also performed. We observed <span class="hlt">freezing</span> onset at 253K for particles of different diameters (0.3, 1.0, 1.8 and 3.2 μm). Most of the droplets were completely frozen by 243K. The number of active sites ranged from 108 to 1012 per m-2. Droplets that contained larger particles (higher surface area) froze at slightly warmer temperatures and contained slightly higher number of active sites. The <span class="hlt">freezing</span> behavior fits well with measurements of K-feldspar particles and this may suggest that the feldspar dominated the dust <span class="hlt">freezing</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4343008','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4343008"><span>Proteomic analyses reveal differences in cold acclimation mechanisms in <span class="hlt">freezing</span>-tolerant and <span class="hlt">freezing</span>-sensitive cultivars of alfalfa</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Chen, Jing; Han, Guiqing; Shang, Chen; Li, Jikai; Zhang, Hailing; Liu, Fengqi; Wang, Jianli; Liu, Huiying; Zhang, Yuexue</p> <p>2015-01-01</p> <p>Cold acclimation in alfalfa (Medicago sativa L.) plays a crucial role in cold tolerance to harsh winters. To examine the cold acclimation mechanisms in <span class="hlt">freezing</span>-tolerant alfalfa (ZD) and <span class="hlt">freezing</span>-sensitive alfalfa (W5), holoproteins, and low-abundance proteins (after the removal of RuBisCO) from leaves were extracted to analyze differences at the protein level. A total of 84 spots were selected, and 67 spots were identified. Of these, the abundance of 49 spots and 24 spots in ZD and W5, respectively, were altered during adaptation to chilling stress. Proteomic results revealed that proteins involved in photosynthesis, protein metabolism, energy metabolism, stress and redox and other proteins were mobilized in adaptation to chilling stress. In ZD, a greater number of changes were observed in proteins, and autologous metabolism and biosynthesis were slowed in response to chilling stress, thereby reducing consumption, allowing for homeostasis. The capability for protein folding and protein biosynthesis in W5 was enhanced, which allows protection against chilling stress. The ability to perceive low temperatures was more sensitive in <span class="hlt">freezing</span>-tolerant alfalfa compared to <span class="hlt">freezing</span>-sensitive alfalfa. This proteomics study provides new insights into the cold acclimation mechanism in alfalfa. PMID:25774161</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1916923D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1916923D"><span>Deposition Nucleation or Pore Condensation and <span class="hlt">Freezing</span>?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>David, Robert O.; Mahrt, Fabian; Marcolli, Claudia; Fahrni, Jonas; Brühwiler, Dominik; Lohmann, Ulrike; Kanji, Zamin A.</p> <p>2017-04-01</p> <p>Ice nucleation plays an important role in moderating Earth's climate and precipitation formation. Over the last century of research, several mechanisms for the nucleation of ice have been identified. Of the known mechanisms for ice nucleation, only deposition nucleation occurs below water saturation. Deposition nucleation is defined as the formation of ice from supersaturated water vapor on an insoluble particle without the prior formation of liquid. However, recent work has found that the efficiency of so-called deposition nucleation shows a dependence on the homogeneous <span class="hlt">freezing</span> temperature of water even though no liquid phase is presumed to be present. Additionally, the ability of certain particles to nucleate ice more efficiently after being pre-cooled (pre-activation) raises questions on the true mechanism when ice nucleation occurs below water saturation. In an attempt to explain the dependence of the efficiency of so-called deposition nucleation on the onset of homogeneous <span class="hlt">freezing</span> of liquid water, pore condensation and <span class="hlt">freezing</span> has been proposed. Pore condensation and <span class="hlt">freezing</span> suggests that the liquid phase can exist under sub-saturated conditions with respect to liquid in narrow confinements or pores due to the inverse Kelvin effect. Once the liquid-phase condenses, it is capable of nucleating ice either homogeneously or heterogeneously. The role of pore condensation and <span class="hlt">freezing</span> is assessed in the Zurich Ice Nucleation Chamber, a continuous flow diffusion chamber, using spherical nonporous and mesoporous silica particles. The mesoporous silica particles have a well-defined particle size range of 400 to 600nm with discreet pore sizes of 2.5, 2.8, 3.5 and 3.8nm. Experiments conducted between 218K and 238K show that so-called deposition nucleation only occurs below the homogenous <span class="hlt">freezing</span> temperature of water and is highly dependent on the presence of pores and their size. The results strongly support pore condensation and <span class="hlt">freezing</span>, questioning the role of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://rosap.ntl.bts.gov/view/dot/29386','DOTNTL'); return false;" href="https://rosap.ntl.bts.gov/view/dot/29386"><span>Predictive modeling of <span class="hlt">freezing</span> and thawing of frost-susceptible soils.</span></a></p> <p><a target="_blank" href="http://ntlsearch.bts.gov/tris/index.do">DOT National Transportation Integrated Search</a></p> <p></p> <p>2015-09-01</p> <p>Frost depth is an essential factor in design of various transportation infrastructures. In frost : susceptible soils, as soils <span class="hlt">freezes</span>, water migrates through the soil voids below the <span class="hlt">freezing</span> line : towards the <span class="hlt">freezing</span> front and causes excessive he...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4434526','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4434526"><span>Multiple Glass Transitions and <span class="hlt">Freezing</span> Events of Aqueous Citric Acid</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2014-01-01</p> <p>Calorimetric and optical cryo-microscope measurements of 10–64 wt % citric acid (CA) solutions subjected to moderate (3 K/min) and slow (0.5 and 0.1 K/min) cooling/warming rates and also to quenching/moderate warming between 320 and 133 K are presented. Depending on solution concentration and cooling rate, the obtained thermograms show one <span class="hlt">freezing</span> event and from one to three liquid–glass transitions upon cooling and from one to six liquid–glass and reverse glass–liquid transitions, one or two <span class="hlt">freezing</span> events, and one melting event upon warming of frozen/glassy CA/H2O. The multiple <span class="hlt">freezing</span> events and glass transitions pertain to the mother CA/H2O solution itself and two <span class="hlt">freeze</span>-concentrated solution regions, FCS1 and FCS2, of different concentrations. The FCS1 and FCS2 (or FCS22) are formed during the <span class="hlt">freezing</span> of CA/H2O upon cooling and/or during the <span class="hlt">freezing</span> upon warming of partly glassy or entirely glassy mother CA/H2O. The formation of two FCS1 and FCS22 regions during the <span class="hlt">freezing</span> upon warming to our best knowledge has never been reported before. Using an optical cryo-microscope, we are able to observe the formation of a continuous ice framework (IF) and its morphology and reciprocal distribution of IF/(FCS1 + FCS2). Our results provide a new look at the <span class="hlt">freezing</span> and glass transition behavior of aqueous solutions and can be used for the optimization of lyophilization and <span class="hlt">freezing</span> of foods and biopharmaceutical formulations, among many other applications where <span class="hlt">freezing</span> plays a crucial role. PMID:25482069</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25597618','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25597618"><span>Application of <span class="hlt">freeze</span>-drying technology in manufacturing orally disintegrating films.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liew, Kai Bin; Odeniyi, Michael Ayodele; Peh, Kok-Khiang</p> <p>2016-01-01</p> <p><span class="hlt">Freeze</span> drying technology has not been maximized and reported in manufacturing orally disintegrating films. The aim of this study was to explore the <span class="hlt">freeze</span> drying technology in the formulation of sildenafil orally disintegrating films and compare the physical properties with heat-dried orally disintegrating film. Central composite design was used to investigate the effects of three factors, namely concentration of carbopol, wheat starch and polyethylene glycol 400 on the tensile strength and disintegration time of the film. Heat-dried films had higher tensile strength than films prepared using <span class="hlt">freeze</span>-dried method. For folding endurance, <span class="hlt">freeze</span>-dried films showed improved endurance than heat-dried films. Moreover, films prepared using <span class="hlt">freeze</span>-dried methods were thicker and had faster disintegration time. Formulations with higher amount of carbopol and starch showed higher tensile strength and thickness whereas formulations with higher PEG 400 content showed better flexibility. Scanning electron microscopy showed that the <span class="hlt">freeze</span>-dried films had more porous structure compared to the heat-dried film as a result of the release of water molecule from the frozen structure when it was subjected to <span class="hlt">freeze</span> drying process. The sildenafil film was palatable. The dissolution profiles of <span class="hlt">freeze</span>-dried and heat-dried films were similar to Viagra® with f2 of 51.04 and 65.98, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011TRACE..16..283I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011TRACE..16..283I"><span>Three-Dimensional Microstructure of Biological Tissues during <span class="hlt">Freezing</span> and Thawing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ishiguro, Hiroshi; Horimizu, Takashi; Kataori, Akinobu; Kajigaya, Hiroshi</p> <p></p> <p>Three-dimensional behavior of ice crystals and cells during the <span class="hlt">freezing</span> and thawing of biological tissues was investigated microscopically in real time by using a confocal laser scanning microscope(CLSM) and a fluorescent dye, acridine orange (AO). Fresh tender meat (2nd pectoral muscles) of chicken was stained with the AO in physiological saline to distinguish ice crystals and cells by their different colors, and then frozen and thawed under two different thermal protocols: a) slow-cooling and rapid-warming and b) rapid-cooling and rapid-warming. The CLSM noninvasively produced optical tomograms of the tissues to clarify the pattern of <span class="hlt">freezing</span>, morphology of ice crystals in the tissues, and the interaction between ice crystals and cells. Also, the tissues were morphologically investigated by pathological means after the <span class="hlt">freezing</span> and thawing. Typical <span class="hlt">freezing</span> pattern during the slow-cooling was extracellular-<span class="hlt">freezing</span>, and those during the rapid-cooling were extracellular-<span class="hlt">freezing</span> and intracellular <span class="hlt">freezing</span> with a lot of fine ice crystals in the cells. Cracks caused by the extracellular and intracellular ice crystals remained in the muscle tissues after the thawing. The results obtained by using the CLSM/dye method were consistent with pathologically morphological changes in the tissues through <span class="hlt">freezing</span> and thawing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16461684','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16461684"><span>Involvement of two specific causes of cell mortality in <span class="hlt">freeze</span>-thaw cycles with <span class="hlt">freezing</span> to -196 degrees C.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dumont, Frédéric; Marechal, Pierre-André; Gervais, Patrick</p> <p>2006-02-01</p> <p>The purpose of this study was to examine cell viability after <span class="hlt">freezing</span>. Two distinct ranges of temperature were identified as corresponding to stages at which yeast cell mortality occurred during <span class="hlt">freezing</span> to -196 degrees C. The upper temperature range was related to the temperature of crystallization of the medium, which was dependent on the solute concentration; in this range mortality was prevented by high solute concentrations, and the proportion of the medium in the vitreous state was greater than the proportion in the crystallized state. The lower temperature range was related to recrystallization that occurred during thawing. Mortality in this temperature range was increased by a high cooling rate and/or high solute concentration in the <span class="hlt">freezing</span> medium and a low temperature (less than -70 degrees C). However, a high rate of thawing prevented yeast mortality in this lower temperature range. Overall, it was found that cell viability could be conserved better under <span class="hlt">freezing</span> conditions by increasing the osmotic pressure of the medium and by using an increased warming rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780010730','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780010730"><span>Design of a blood-<span class="hlt">freezing</span> system for leukemia research</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Williams, T. E.; Cygnarowicz, T. A.</p> <p>1978-01-01</p> <p>Leukemia research involves the use of cryogenic <span class="hlt">freezing</span> and storage equipment. In a program being carried out at the National Cancer Institute (NCI), bone marrow (white blood cells) was frozen using a standard cryogenic biological freezer. With this system, it is difficult to maintain the desired rate of <span class="hlt">freezing</span> and repeatability from sample to sample. A <span class="hlt">freezing</span> system was developed that satisfies the requirements for a repeatable, constant <span class="hlt">freezing</span> rate. The system was delivered to NIC and is now operational. This report describes the design of the major subsystems, the analyses, the operating procedure, and final system test results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29537685','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29537685"><span>An RNA-Cleaving Catalytic DNA Accelerated by <span class="hlt">Freezing</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yu, Tianmeng; Zhou, Wenhu; Liu, Juewen</p> <p>2018-05-18</p> <p>The EtNa DNAzyme was isolated during the isopropanol precipitation step of an in vitro selection effort. Although inactive with the intended cofactor, its RNA cleavage activity was observed under a few conditions. With Na + , EtNa was highly active in ∼50 % ethanol, whereas in water, it was highly active with Ca 2+ . In this work, we showed that the EtNa DNAzyme was accelerated by <span class="hlt">freezing</span> in water in the presence of Na + . The apparent K d value reached 6.2 mm Na + under the frozen condition, over 20 times tighter than that in water at room temperature. With 10 mm Na + , EtNa had a cleavage rate of 0.12 h -1 after <span class="hlt">freezing</span> at -20 °C. This effect was unique to EtNa, as all other tested DNAzymes were inhibited by <span class="hlt">freezing</span> except for the Na + -specific NaA43. <span class="hlt">Freezing</span> also inhibited EtNa if Ca 2+ was used. We attributed this to the concentrations of EtNa and Na + in the micropockets between ice crystals, but divalent metals might misfold DNA. Overall, we have systematically studied the effect of <span class="hlt">freezing</span> on the RNA-cleavage activity of DNAzymes. The DNAzyme sequence and the metal ion species are both crucial to determine the effect of <span class="hlt">freezing</span>. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730000092','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730000092"><span>Preservation of flavor in <span class="hlt">freeze</span> dried green beans</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Huber, C. S.; Heidelbaugh, N. D.; Davis, D.</p> <p>1973-01-01</p> <p>Before <span class="hlt">freeze</span> drying, green beans are heated to point at which their cell structure is altered. Beans <span class="hlt">freeze</span> dried with altered cell structure have improved rehydration properties and retain color, flavor, and texture.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1377529','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1377529"><span>Controllable growth of <span class="hlt">vertically</span> aligned graphene on C-face SiC</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Liu, Yu; Chen, Lianlian; Hilliard, Donovan</p> <p></p> <p>We investigated how to control the growth of <span class="hlt">vertically</span> aligned graphene on C-face SiC by varying the processing conditions. It is found that, the growth rate scales with the annealing temperature and the graphene height is proportional to the annealing time. Temperature <span class="hlt">gradient</span> and crystalline quality of the SiC substrates influence their vaporization. The partial vapor pressure is crucial as it can interfere with further vaporization. A growth mechanism is proposed in terms of physical vapor transport. The monolayer character of <span class="hlt">vertically</span> aligned graphene is verified by Raman and X-ray absorption spectroscopy. With the processed samples, d 0 magnetism ismore » realized and negative magnetoresistance is observed after Cu implantation. We also prove that multiple carriers exist in <span class="hlt">vertically</span> aligned graphene.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1377529-controllable-growth-vertically-aligned-graphene-face-sic','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1377529-controllable-growth-vertically-aligned-graphene-face-sic"><span>Controllable growth of <span class="hlt">vertically</span> aligned graphene on C-face SiC</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Liu, Yu; Chen, Lianlian; Hilliard, Donovan; ...</p> <p>2016-10-06</p> <p>We investigated how to control the growth of <span class="hlt">vertically</span> aligned graphene on C-face SiC by varying the processing conditions. It is found that, the growth rate scales with the annealing temperature and the graphene height is proportional to the annealing time. Temperature <span class="hlt">gradient</span> and crystalline quality of the SiC substrates influence their vaporization. The partial vapor pressure is crucial as it can interfere with further vaporization. A growth mechanism is proposed in terms of physical vapor transport. The monolayer character of <span class="hlt">vertically</span> aligned graphene is verified by Raman and X-ray absorption spectroscopy. With the processed samples, d 0 magnetism ismore » realized and negative magnetoresistance is observed after Cu implantation. We also prove that multiple carriers exist in <span class="hlt">vertically</span> aligned graphene.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29550375','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29550375"><span><span class="hlt">Freezing</span> of gait: Promising avenues for future treatment.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gilat, Moran; Lígia Silva de Lima, Ana; Bloem, Bastiaan R; Shine, James M; Nonnekes, Jorik; Lewis, Simon J G</p> <p>2018-03-12</p> <p><span class="hlt">Freezing</span> of gait is a devastating symptom of Parkinson's disease and other forms of parkinsonism. It poses a major burden on both patients and their families, as <span class="hlt">freezing</span> often leads to falls, fall-related injuries and a loss of independence. Treating <span class="hlt">freezing</span> of gait is difficult for a variety of reasons: it has a paroxysmal and unpredictable nature; a multifaceted pathophysiology, with an interplay between motor elements (disturbed stepping mechanisms) and non-motor elements (cognitive decline, anxiety); and a complex (and likely heterogeneous) underlying neural substrate, involving multiple failing neural networks. In recent years, advances in translational neuroscience have offered new insights into the pathophysiology underlying <span class="hlt">freezing</span>. Furthermore, the mechanisms behind the effectiveness of available treatments (or lack thereof) are better understood. Driven by these concepts, researchers and clinicians have begun to improve currently available treatment options, and develop new and better treatment methods. Here, we evaluate the range of pharmacological (i.e. closed-looped approaches), surgical (i.e. multi-target and adaptive deep brain and spinal cord stimulation) and behavioural (i.e. biofeedback and cueing on demand) treatment options that are under development, and propose novel avenues that are likely to play a crucial role in the clinical management of <span class="hlt">freezing</span> of gait in the near future. The outcomes of this review suggest that the successful future management of <span class="hlt">freezing</span> of gait will require individualized treatments that can be implemented in an on-demand manner in response to imminent <span class="hlt">freezing</span>. With this review we hope to guide much-needed advances in treating this devastating symptom of Parkinson's disease. Copyright © 2018 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4481992','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4481992"><span>Novel Real-Time Diagnosis of the <span class="hlt">Freezing</span> Process Using an Ultrasonic Transducer</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Tseng, Yen-Hsiang; Cheng, Chin-Chi; Cheng, Hong-Ping; Lee, Dasheng</p> <p>2015-01-01</p> <p>The <span class="hlt">freezing</span> stage governs several critical parameters of the <span class="hlt">freeze</span> drying process and the quality of the resulting lyophilized products. This paper presents an integrated ultrasonic transducer (UT) in a stainless steel bottle and its application to real-time diagnostics of the water <span class="hlt">freezing</span> process. The sensor was directly deposited onto the stainless steel bottle using a sol-gel spray technique. It could operate at temperature range from −100 to 400 °C and uses an ultrasonic pulse-echo technique. The progression of the <span class="hlt">freezing</span> process, including water-in, <span class="hlt">freezing</span> point and final phase change of water, were all clearly observed using ultrasound. The ultrasonic signals could indicate the three stages of the <span class="hlt">freezing</span> process and evaluate the cooling and <span class="hlt">freezing</span> periods under various processing conditions. The temperature was also adopted for evaluating the cooling and <span class="hlt">freezing</span> periods. These periods increased with water volume and decreased with shelf temperature (i.e., speed of <span class="hlt">freezing</span>). This study demonstrates the effectiveness of the ultrasonic sensor and technology for diagnosing and optimizing the process of water <span class="hlt">freezing</span> to save energy. PMID:25946629</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title7-vol3/pdf/CFR-2013-title7-vol3-sec58-638.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title7-vol3/pdf/CFR-2013-title7-vol3-sec58-638.pdf"><span>7 CFR 58.638 - <span class="hlt">Freezing</span> the mix.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-01-01</p> <p>... 7 Agriculture 3 2013-01-01 2013-01-01 false <span class="hlt">Freezing</span> the mix. 58.638 Section 58.638 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards... Procedures § 58.638 <span class="hlt">Freezing</span> the mix. After the mix enters the freezer, it shall be frozen as rapidly as...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title7-vol3/pdf/CFR-2012-title7-vol3-sec58-638.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title7-vol3/pdf/CFR-2012-title7-vol3-sec58-638.pdf"><span>7 CFR 58.638 - <span class="hlt">Freezing</span> the mix.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-01-01</p> <p>... 7 Agriculture 3 2012-01-01 2012-01-01 false <span class="hlt">Freezing</span> the mix. 58.638 Section 58.638 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards... Procedures § 58.638 <span class="hlt">Freezing</span> the mix. After the mix enters the freezer, it shall be frozen as rapidly as...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title7-vol3/pdf/CFR-2014-title7-vol3-sec58-638.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title7-vol3/pdf/CFR-2014-title7-vol3-sec58-638.pdf"><span>7 CFR 58.638 - <span class="hlt">Freezing</span> the mix.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-01-01</p> <p>... 7 Agriculture 3 2014-01-01 2014-01-01 false <span class="hlt">Freezing</span> the mix. 58.638 Section 58.638 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards... Procedures § 58.638 <span class="hlt">Freezing</span> the mix. After the mix enters the freezer, it shall be frozen as rapidly as...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title23-vol1/pdf/CFR-2010-title23-vol1-sec658-23.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title23-vol1/pdf/CFR-2010-title23-vol1-sec658-23.pdf"><span>23 CFR 658.23 - LCV <span class="hlt">freeze</span>; cargo-carrying unit <span class="hlt">freeze</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-04-01</p> <p>... safety purposes and road construction, a State may make minor adjustments of a temporary and emergency... decision is reached that minor adjustments made by a State are not legitimately attributable to road or bridge construction or safety, the FHWA will inform the State, and the original conditions of the <span class="hlt">freeze</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1761990','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1761990"><span>Embolism Formation during <span class="hlt">Freezing</span> in the Wood of Picea abies1</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Mayr, Stefan; Cochard, Hervé; Améglio, Thierry; Kikuta, Silvia B.</p> <p>2007-01-01</p> <p><span class="hlt">Freeze</span>-thaw events can cause embolism in plant xylem. According to classical theory, gas bubbles are formed during <span class="hlt">freezing</span> and expand during thawing. Conifers have proved to be very resistant to <span class="hlt">freeze</span>-thaw induced embolism, because bubbles in tracheids are small and redissolve during thawing. In contrast, increasing embolism rates upon consecutive <span class="hlt">freeze</span>-thaw events were observed that cannot be explained by the classical mechanism. In this study, embolism formation during <span class="hlt">freeze</span>-thaw events was analyzed via ultrasonic and Cryo-scanning electron microscope techniques. Twigs of Picea abies L. Karst. were subjected to up to 120 <span class="hlt">freeze</span>-thaw cycles during which ultrasonic acoustic emissions, xylem temperature, and diameter variations were registered. In addition, the extent and cross-sectional pattern of embolism were analyzed with staining experiments and Cryo-scanning electron microscope observations. Embolism increased with the number of <span class="hlt">freeze</span>-thaw events in twigs previously dehydrated to a water potential of −2.8 MPa. In these twigs, acoustic emissions were registered, while saturated twigs showed low, and totally dehydrated twigs showed no, acoustic activity. Acoustic emissions were detected only during the <span class="hlt">freezing</span> process. This means that embolism was formed during <span class="hlt">freezing</span>, which is in contradiction to the classical theory of <span class="hlt">freeze</span>-thaw induced embolism. The clustered pattern of embolized tracheids in cross sections indicates that air spread from a dysfunctional tracheid to adjacent functional ones. We hypothesize that the low water potential of the growing ice front led to a decrease of the potential in nearby tracheids. This may result in <span class="hlt">freezing</span>-induced air seeding. PMID:17041033</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25776740','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25776740"><span>Experimental analysis and modeling of ultrasound assisted <span class="hlt">freezing</span> of potato spheres.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kiani, Hossein; Zhang, Zhihang; Sun, Da-Wen</p> <p>2015-09-01</p> <p>In recent years, innovative methods such as ultrasound assisted <span class="hlt">freezing</span> have been developed in order to improve the <span class="hlt">freezing</span> process. During <span class="hlt">freezing</span> of foods, accurate prediction of the temperature distribution, phase ratios, and process time is very important. In the present study, ultrasound assisted immersion <span class="hlt">freezing</span> process (in 1:1 ethylene glycol-water solution at 253.15K) of potato spheres (0.02 m diameter) was evaluated using experimental, numerical and analytical approaches. Ultrasound (25 kHz, 890 W m(-2)) was irradiated for different duty cycles (DCs=0-100%). A finite volume based enthalpy method was used in the numerical model, based on which temperature and liquid fraction profiles were simulated by a program developed using OpenFOAM® CFD software. An analytical technique was also employed to calculate <span class="hlt">freezing</span> times. The results showed that ultrasound irradiation could decrease the characteristic <span class="hlt">freezing</span> time of potatoes. Since ultrasound irradiation increased the heat transfer coefficient but simultaneously generated heat at the surface of the samples, an optimum DC was needed for the shortest <span class="hlt">freezing</span> time which occurred in the range of 30-70% DC. DCs higher than 70% increased the <span class="hlt">freezing</span> time. DCs lower than 30% did not provide significant effects on the <span class="hlt">freezing</span> time compared to the control sample. The numerical model predicted the characteristic <span class="hlt">freezing</span> time in accordance with the experimental results. In addition, analytical calculation of characteristic <span class="hlt">freezing</span> time exhibited qualitative agreement with the experimental results. As the numerical simulations provided profiles of temperature and water fraction within potatoes frozen with or without ultrasound, the models can be used to study and control different operation situations, and to improve the understanding of the <span class="hlt">freezing</span> process. Copyright © 2015 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.7515H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.7515H"><span>Heterogeneous <span class="hlt">freezing</span> of super cooled water droplets in micrometre range- <span class="hlt">freezing</span> on a chip</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Häusler, Thomas; Witek, Lorenz; Felgitsch, Laura; Hitzenberger, Regina; Grothe, Hinrich</p> <p>2017-04-01</p> <p>A new setup to analyse the <span class="hlt">freezing</span> behaviour of ice nucleation particles (INPs) dispersed in aqueous droplets has been developed with the aim to analyse ensembles of droplets with sizes in the micrometre range, in which INPs are immersed. Major disadvantages of conventional drop-<span class="hlt">freezing</span> experiments like varying drop sizes or interactions between the water- oil mixture and the INP, were solved by introducing a unique <span class="hlt">freezing</span>- chip consisting of an etched and sputtered 15x15x1 mm gold-plated silicon or pure gold film (Pummer et al., 2012; Zolles et al., 2015). Using this chip, isolated micrometre-sized droplets can be generated with sizes similar to droplets in real world clouds. The experimental set-up for drop-<span class="hlt">freezing</span> experiments was revised and improved by establishing automated process control and image evaluation. We were able to show the efficiency and accuracy of our setup by comparing measured <span class="hlt">freezing</span> temperatures of different INPs (Snomax®, K- feldspar, birch pollen (Betula pendula) washing water, juniper pollen suspension (Juniperus communis) and ultrapure water) with already published results (Atkinson et al., 2013; Augustin et al., 2013; Pruppacher and Klett, 1997; Pummer et al., 2012; Wex et al., 2015; Zolles et al., 2015). Comparison of our measurements with literature data show the important impact of droplet size, INP concentration and number of active sites on the T50 values. Here, the new set-up exhibits its strength in reproducibility and accuracy which is due to the defined and isolated droplets. Finally, it opens a temperature window down to -37˚ C for <span class="hlt">freezing</span> experiments which was not accessible with former traditional approaches .Atkinson, J. D., Murray, B. J., Woodhouse, M. T., Whale, T. F., Baustian, K. J., Carslaw, K. S., Dobbie, S., O'Sullivan, D., and Malkin, T. L.: The importance of feldspar for ice nucleation by mineral dust in mixed-phase clouds (vol 498, pg 355, 2013), Nature, 500, 491-491, 2013. Augustin, S., Wex, H</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018QuIP...17..127Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018QuIP...17..127Y"><span>Preparation of <span class="hlt">freezing</span> quantum state for quantum coherence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Lian-Wu; Man, Zhong-Xiao; Zhang, Ying-Jie; Han, Feng; Du, Shao-jiang; Xia, Yun-Jie</p> <p>2018-06-01</p> <p>We provide a method to prepare the <span class="hlt">freezing</span> quantum state for quantum coherence via unitary operations. The initial product state consists of the control qubit and target qubit; when it satisfies certain conditions, the initial product state converts into the particular Bell diagonal state under the unitary operations, which have the property of <span class="hlt">freezing</span> of quantum coherence under quantum channels. We calculate the frozen quantum coherence and corresponding quantum correlations, and find that the quantities are determined by the control qubit only when the <span class="hlt">freezing</span> phenomena occur.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1578759','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1578759"><span>Sinking velocities of phytoplankton measured on a stable density <span class="hlt">gradient</span> by laser scanning</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Walsby, Anthony E; Holland, Daryl P</p> <p>2005-01-01</p> <p>Two particular difficulties in measuring the sinking velocities of phytoplankton cells are preventing convection within the sedimenting medium and determining the changing depth of the cells. These problems are overcome by using a density-stabilized sedimentation column scanned by a laser. For freshwater species, a suspension of phytoplankton is layered over a <span class="hlt">vertical</span> density <span class="hlt">gradient</span> of Percoll solution; as the cells sink down the column their relative concentration is measured by the forward scattering of light from a laser beam that repeatedly scans up and down the column. The Percoll <span class="hlt">gradient</span> stabilizes the column, preventing <span class="hlt">vertical</span> mixing by convection, radiation or perturbation of density by the descending cells. Measurements were made on suspensions of 15 μm polystyrene microspheres with a density of 1050 kg m−3; the mean velocity was 6.28 μm s−1, within 1.5% of that calculated by the Stokes equation, 6.36 μm s−1. Measurements made on the filamentous cyanobacterium Planktothrix rubescens gave mean velocities within the theoretical range of values based on the range of size, shape, orientation and density of the particles in a modified Stokes equation. Measurements on marine phytoplankton may require density <span class="hlt">gradients</span> prepared with other substances. PMID:16849271</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920041973&hterms=conjugate+gradient&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dconjugate%2Bgradient','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920041973&hterms=conjugate+gradient&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dconjugate%2Bgradient"><span>Natural convection in binary gases driven by combined horizontal thermal and <span class="hlt">vertical</span> solutal <span class="hlt">gradients</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Weaver, J. A.; Viskanta, Raymond</p> <p>1992-01-01</p> <p>An investigation of natural convection is presented to examine the influence of a horizontal temperature <span class="hlt">gradient</span> and a concentration <span class="hlt">gradient</span> occurring from the bottom to the cold wall in a cavity. As the solutal buoyancy force changes from augmenting to opposing the thermal buoyancy force, the fluid motion switches from unicellular to multicellular flow (fluid motion is up the cold wall and down the hot wall for the bottom counterrotating flow cell). Qualitatively, the agreement between predicted streamlines and smoke flow patterns is generally good. In contrast, agreement between measured and predicted temperature and concentration distributions ranges from fair to poor. Part of the discrepancy can be attributed to experimental error. However, there remains considerable discrepancy between data and predictions due to the idealizations of the mathematical model, which examines only first-order physical effects. An unsteady flow, variable thermophysical properties, conjugate effects, species interdiffusion, and radiation were not accounted for in the model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920001528','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920001528"><span>Horizontal stress in planetary lithospheres from <span class="hlt">vertical</span> processes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Banerdt, W. B.</p> <p>1991-01-01</p> <p>Understanding the stress states in a lithosphere is of fundamental importance for planetary geophysics. It is closely linked to the processes which form and modify tectonic features on the surface and reflects the behavior of the planet's interior, providing a constraint for the difficult problem of determining interior structure and processes. The tectonics on many extraterrestrial bodies (Moon, Mars, and most of the outer planet satellites) appears to be mostly <span class="hlt">vertical</span>, and the horizontal stresses induced by <span class="hlt">vertical</span> motions and loads are expected to dominate the deformation of their lithospheres. Herein, only changes are examined in the state of stress induced by processes such as sedimentary and volcanic deposition, erosional denudation, and changes in the thermal <span class="hlt">gradient</span> that induce uplift or subsidence. This analysis is important both for evaluating stresses for specific regions in which the <span class="hlt">vertical</span> stress history can be estimated, as well as for applying the proper loading conditions to global stress models. All references to lithosphere herein should be understood to refer to the elastic lithosphere, that layer which deforms elastically or brittlely when subjected to geologically scaled stresses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22696938-isochoric-isobaric-freezing-fish-muscle','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22696938-isochoric-isobaric-freezing-fish-muscle"><span>Isochoric and isobaric <span class="hlt">freezing</span> of fish muscle</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Năstase, Gabriel; Department of Building Services, University of Transilvania, Braşov, Braşov, 500152; Lyu, Chenang</p> <p></p> <p>We have recently shown that, a living organism, which succumbs to <span class="hlt">freezing</span> to −4 °C in an isobaric thermodynamic system (constant atmospheric pressure), can survive <span class="hlt">freezing</span> to −4 °C in an isochoric thermodynamic system (constant volume). It is known that the mechanism of cell damage in an isobaric system is the <span class="hlt">freezing</span> caused increase in extracellular osmolality, and, the consequent cell dehydration. An explanation for the observed survival during isochoric <span class="hlt">freezing</span> is the thermodynamic modeling supported hypothesis that, in the isochoric frozen solution the extracellular osmolality is comparable to the cell intracellular osmolality. Therefore, cells in the isochoric frozen organism do not dehydrate, andmore » the tissue maintains its morphological integrity. Comparing the histology of: a) fresh fish white muscle, b) fresh muscle frozen to −5 °C in an isobaric system and c) fresh muscle frozen to −5 °C I in an isochoric system, we find convincing evidence of the mechanism of cell dehydration during isobaric <span class="hlt">freezing</span>. In contrast, the muscle tissue frozen to −5 °C in an isochoric system appears morphologically identical to fresh tissue, with no evidence of dehydration. This is the first experimental evidence in support of the hypothesis that in isochoric <span class="hlt">freezing</span> there is no cellular dehydration and therefore the morphology of the frozen tissue remains intact. - Highlights: • Preservation of fish muscle at, subfreezing temperatures, in an isochoric system, is demonstrated. • Experiments were performed to an average pressure of 41.3 MPa and temperatures of −5 °C. • Isochoric subfreezing temperature is a new preservation method that does not require the.use of cryoprotectants. • No cellular dehydration and therefore the morphology of the frozen tissue remains intact.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15042231','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15042231"><span>Hepatitis B vaccine <span class="hlt">freezing</span> in the Indonesian cold chain: evidence and solutions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nelson, Carib M; Wibisono, Hariadi; Purwanto, Hary; Mansyur, Isa; Moniaga, Vanda; Widjaya, Anton</p> <p>2004-02-01</p> <p>To document and characterize <span class="hlt">freezing</span> temperatures in the Indonesian vaccine cold chain and to evaluate the feasibility of changes designed to reduce the occurrence of <span class="hlt">freezing</span>. Data loggers were used to measure temperatures of shipments of hepatitis B vaccine from manufacturer to point of use. Baseline conditions and three intervention phases were monitored. During each of the intervention phases, vaccines were removed progressively from the standard 2-8 degrees C cold chain. <span class="hlt">Freezing</span> temperatures were recorded in 75% of baseline shipments. The highest rates of <span class="hlt">freezing</span> occurred during transport from province to district, storage in district-level ice-lined refrigerators, and storage in refrigerators in health centres. Interventions reduced <span class="hlt">freezing</span>, without excessive heat exposure. Inadvertent <span class="hlt">freezing</span> of <span class="hlt">freeze</span>-sensitive vaccines is widespread in Indonesia. Simple strategies exist to reduce <span class="hlt">freezing</span> - for example, selective transport and storage of vaccines at ambient temperatures. The use of vaccine vial monitors reduces the risk associated with heat-damaged vaccines in these scenarios. Policy changes that allow limited storage of <span class="hlt">freeze</span>-sensitive vaccines at temperatures >2-8 degrees C would enable flexible vaccine distribution strategies that could reduce vaccine <span class="hlt">freezing</span>, reduce costs, and increase capacity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA630298','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA630298"><span>Coupling Behavior and <span class="hlt">Vertical</span> Distribution of Pteropods in Coastal Waters using Data from the Video Plankton Recorder</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1999-09-30</p> <p>Coupling Behavior and <span class="hlt">Vertical</span> Distribution of Pteropods in Coastal Waters using Data from the Video Plankton Recorder Scott M. Gallager Woods Hole...<span class="hlt">gradients</span>. OBJECTIVES My objective in this project is to test the hypothesis that the <span class="hlt">vertical</span> distribution of the pteropod Limacina retroversa...the mini-VPR are being used to infer behavior of individual pteropods . Third, a random walk turbulence model with behavioral feed-back is providing</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996ApPhL..68.1537H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996ApPhL..68.1537H"><span>Complete p-type activation in <span class="hlt">vertical-gradient</span> <span class="hlt">freeze</span> GaAs co-implanted with gallium and carbon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Horng, S. T.; Goorsky, M. S.</p> <p>1996-03-01</p> <p>High-resolution triple-axis x-ray diffractometry and Hall-effect measurements were used to characterize damage evolution and electrical activation in gallium arsenide co-implanted with gallium and carbon ions. Complete p-type activation of GaAs co-implanted with 5×1014 Ga cm-2 and 5×1014 C cm-2 was achieved after rapid thermal annealing at 1100 °C for 10 s. X-ray diffuse scattering was found to increase after rapid thermal annealing at 600-900 °C due to the aggregation of implantation-induced point defects. In this annealing range, there was ˜10%-72% activation. After annealing at higher annealing temperatures, the diffuse scattered intensity decreased drastically; samples that had been annealed at 1000 °C (80% activated) and 1100 °C (˜100% activated) exhibited reciprocal space maps that were indicative of high crystallinity. The hole mobility was about 60 cm2/V s for all samples annealed at 800 °C and above, indicating that the crystal perfection influences dopant activation more strongly than it influences mobility. Since the high-temperature annealing simultaneously increases dopant activation and reduces x-ray diffuse scattering, we conclude that point defect complexes which form at lower annealing temperatures are responsible for both the diffuse scatter and the reduced activation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910029371&hterms=vertical+height&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dvertical%2Bheight','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910029371&hterms=vertical+height&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dvertical%2Bheight"><span>Experimental observation of the influence of furnace temperature profile on convection and segregation in the <span class="hlt">vertical</span> Bridgman crystal growth technique</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Neugebauer, G. T.; Wilcox, W. R.</p> <p>1990-01-01</p> <p>Azulene-doped naphtalene was directionally solidified using the <span class="hlt">vertical</span> Bridgman-Stockbarger technique. Doping homogeneity and convection are determined as a function of the temperature profile in the furnace and the <span class="hlt">freezing</span> rate. Convective velocities are two orders of magnitude lower when the temperature increases with height. The cross sectional variation in azulene concentration tends to be asymmetric. Neither rotation of the ampoule nor deliberate introduction of thermal asymmetries during solidification had a significant influence on cross sectional variations in doping. It is predicted that slow directional solidification under microgravity conditions can produce greater inhomogeneities than on earth. Thus when low <span class="hlt">freezing</span> rates are necessary in order to avoid constitutional supercooling, it may be necessary to combine microgravity and magnetic fields in order to achieve homogeneous crystals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://rosap.ntl.bts.gov/view/dot/13248','DOTNTL'); return false;" href="https://rosap.ntl.bts.gov/view/dot/13248"><span><span class="hlt">Freezing</span> temperature protection admixture for Portland cement concrete</span></a></p> <p><a target="_blank" href="http://ntlsearch.bts.gov/tris/index.do">DOT National Transportation Integrated Search</a></p> <p></p> <p>1996-10-01</p> <p>A number of experimental admixtures were compared to Pozzutec 20 admixture for their ability to protect fresh concrete from <span class="hlt">freezing</span> and for increasing the rate of cement hydration at below-<span class="hlt">freezing</span> temperatures. The commercial accelerator and low-te...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720010455','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720010455"><span>Development of <span class="hlt">freeze</span> dried vegetables</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Larson, R. W.</p> <p>1970-01-01</p> <p>The development of <span class="hlt">freeze</span> dried vegetables to be used in the Apollo food system is discussed. After the initial selection and screening of vegetables, several types of <span class="hlt">freeze</span> dried vegetables were prepared in small batches. From these small batches, two vegetables were judged satisfactory for further testing and evaluation. These vegetables, mashed potatoes and asparagus, were subjected to storage at 100 deg plus or minus 5 F. for two weeks and then taste tested. The vegetables were also tested to determine if they complied with the microbiological requirements for Apollo food. The space food prototype production guide for the vegetables is submitted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011aogs...22...77C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011aogs...22...77C"><span>Investigation of Ionospheric Spatial <span class="hlt">Gradients</span> for Gagan Error Correction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chandra, K. Ravi</p> <p></p> <p>In India, Indian Space Research Organization (ISRO) has established with an objective to develop space technology and its application to various national tasks. The national tasks include, establishment of major space systems such as Indian National Satellites (INSAT) for communication, television broadcasting and meteorological services, Indian Remote Sensing Satellites (IRS), etc. Apart from these, to cater to the needs of civil aviation applications, GPS Aided Geo Augmented Navigation (GAGAN) system is being jointly implemented along with Airports Authority of India (AAI) over the Indian region. The most predominant parameter affecting the navigation accuracy of GAGAN is ionospheric delay which is a function of total number of electrons present in one square meter cylindrical cross-sectional area in the line of site direction between the satellite and the user on the earth, i.e. Total Electron Content (TEC). In the equatorial and low latitude regions such as India, TEC is often quite high with large spatial <span class="hlt">gradients</span>. Carrier phase data from the GAGAN network of Indian TEC Stations is used for estimating and identifying ionospheric spatial <span class="hlt">gradients</span> inmultiple viewing directions. In this paper amongst the satellite signals arriving in multipledirections,<span class="hlt">Vertical</span> ionospheric <span class="hlt">gradients</span> (σVIG) are calculated, inturn spatial ionospheric <span class="hlt">gradients</span> are identified. In addition, estimated temporal <span class="hlt">gradients</span>, i.e. rate of TEC Index is also compared. These aspects which contribute to errors can be treated for improved GAGAN system performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006cosp...36.3165N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006cosp...36.3165N"><span>Use of Total Electron Content data to analyze ionosphere electron density <span class="hlt">gradients</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nava, B.; Radicella, S. M.; Leitinger, R.; Coisson, P.</p> <p></p> <p>In presence of electron density <span class="hlt">gradients</span> the thin shell approximation for the ionosphere used together with a simple mapping function to convert slant Total Electron Content TEC to <span class="hlt">vertical</span> TEC could lead to TEC conversion errors Therefore these mapping function errors can be used to identify the effects of the electron density <span class="hlt">gradients</span> in the ionosphere In the present work high precision GPS derived slant TEC data have been used to investigate the effects of the electron density <span class="hlt">gradients</span> in the middle and low latitude ionosphere under geomagnetic quiet and disturbed conditions In particular the data corresponding to the geographic area of the American sector for the days 5-7 April 2000 have been used to perform a complete analysis of mapping function errors based on the coinciding pierce point technique The results clearly illustrate the electron density <span class="hlt">gradient</span> effects according to the locations considered and to the actual levels of disturbance of the ionosphere</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018E%26ES..128a2095X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018E%26ES..128a2095X"><span>Research on strength attenuation law of concrete in <span class="hlt">freezing</span> - thawing environment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiao, qianhui; Cao, zhiyuan; Li, qiang</p> <p>2018-03-01</p> <p>By rapid <span class="hlt">freezing</span> and thawing method, the experiments of concrete have been 300 <span class="hlt">freeze</span>-thaw cycles specimens in the water. The cubic compression strength value under different <span class="hlt">freeze</span>-thaw cycles was measured. By analyzing the test results, the water-binder ratio of the concrete under <span class="hlt">freeze</span>-thaw environments, fly ash and air entraining agent is selected dosage recommendations. The exponential attenuation prediction model and life prediction model of compression strength of concrete under <span class="hlt">freezing</span>-thawing cycles considering the factors of water-binder ratio, fly ash content and air-entraining agent dosage were established. The model provides the basis for predicting the durability life of concrete under <span class="hlt">freezing</span>-thawing environment. It also provides experimental basis and references for further research on concrete structures with antifreeze requirements.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://rosap.ntl.bts.gov/view/dot/27866','DOTNTL'); return false;" href="https://rosap.ntl.bts.gov/view/dot/27866"><span>Water vapor movement in <span class="hlt">freezing</span> aggregate base materials.</span></a></p> <p><a target="_blank" href="http://ntlsearch.bts.gov/tris/index.do">DOT National Transportation Integrated Search</a></p> <p></p> <p>2014-06-01</p> <p>The objectives of this research were to 1) measure the extent to which water vapor movement results in : water accumulation in <span class="hlt">freezing</span> base materials; 2) evaluate the effect of soil stabilization on water vapor movement : in <span class="hlt">freezing</span> base materials;...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://files.eric.ed.gov/fulltext/ED134396.pdf','ERIC'); return false;" href="http://files.eric.ed.gov/fulltext/ED134396.pdf"><span>St. Lawrence River <span class="hlt">Freeze</span>-Up Forecast Procedure.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Assel, R. A.</p> <p></p> <p>A standard operating procedure (SOP) is presented for calculating the date of <span class="hlt">freeze</span>-up on the St. Lawrence River at Massena, N.Y. The SOP is based on two empirical temperature decline equations developed for Kingston, Ontario, and Massena, N.Y., respectively. Input data needed to forecast <span class="hlt">freeze</span>-up consist of the forecast December flow rate and…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25668668','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25668668"><span>A <span class="hlt">freeze</span>-stable formulation for DTwP and DTaP vaccines.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xue, Honggang; Yang, Bangling; Kristensen, Debra D; Chen, Dexiang</p> <p>2014-01-01</p> <p>Inadvertent vaccine <span class="hlt">freezing</span> often occurs in the cold chain and may cause damage to freeze‑sensitive vaccines. Liquid vaccines that contain aluminum salt adjuvants are particularly vulnerable. Polyol cryoprotective excipients have been shown to prevent <span class="hlt">freeze</span> damage to hepatitis B vaccine. In this study, we examined the <span class="hlt">freeze</span>-protective effect of propylene glycol on diphtheria-tetanus-pertussis-whole-cell (DTwP) and acellular (DTaP) vaccines. Pilot lots of DTwP and DTaP formulated with 7.5% propylene glycol underwent 3 <span class="hlt">freeze</span>-thaw treatments. The addition of propylene glycol had no impact on pH, particle size distribution, or potency of the vaccines prior to <span class="hlt">freeze</span>-thaw treatment; the only change noted was an increase in osmolality. The potencies and the physical properties of the vaccines containing cryoprotectant were maintained after <span class="hlt">freeze</span>-thawing and for 3 months in accelerated stability studies. The results from this study indicate that formulating vaccines with propylene glycol can protect diphtheria-tetanus-pertussis vaccines against <span class="hlt">freeze</span> damages.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19163288','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19163288"><span>The equivalent magnetizing method applied to the design of <span class="hlt">gradient</span> coils for MRI.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lopez, Hector Sanchez; Liu, Feng; Crozier, Stuart</p> <p>2008-01-01</p> <p>This paper presents a new method for the design of <span class="hlt">gradient</span> coils for Magnetic Resonance Imaging systems. The method is based on the equivalence between a magnetized volume surrounded by a conducting surface and its equivalent representation in surface current/charge density. We demonstrate that the curl of the <span class="hlt">vertical</span> magnetization induces a surface current density whose stream line defines the coil current pattern. This method can be applied for coils wounds on arbitrary surface shapes. A single layer unshielded transverse <span class="hlt">gradient</span> coil is designed and compared, with the designs obtained using two conventional methods. Through the presented example we demonstrate that the generated unconventional current patterns obtained using the magnetizing current method produces a superior <span class="hlt">gradient</span> coil performance than coils designed by applying conventional methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1392953','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1392953"><span>Involvement of Two Specific Causes of Cell Mortality in <span class="hlt">Freeze</span>-Thaw Cycles with <span class="hlt">Freezing</span> to −196°C</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dumont, Frédéric; Marechal, Pierre-André; Gervais, Patrick</p> <p>2006-01-01</p> <p>The purpose of this study was to examine cell viability after <span class="hlt">freezing</span>. Two distinct ranges of temperature were identified as corresponding to stages at which yeast cell mortality occurred during <span class="hlt">freezing</span> to −196°C. The upper temperature range was related to the temperature of crystallization of the medium, which was dependent on the solute concentration; in this range mortality was prevented by high solute concentrations, and the proportion of the medium in the vitreous state was greater than the proportion in the crystallized state. The lower temperature range was related to recrystallization that occurred during thawing. Mortality in this temperature range was increased by a high cooling rate and/or high solute concentration in the <span class="hlt">freezing</span> medium and a low temperature (less than −70°C). However, a high rate of thawing prevented yeast mortality in this lower temperature range. Overall, it was found that cell viability could be conserved better under <span class="hlt">freezing</span> conditions by increasing the osmotic pressure of the medium and by using an increased warming rate. PMID:16461684</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JChPh.147f0901H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JChPh.147f0901H"><span>Perspective: Surface <span class="hlt">freezing</span> in water: A nexus of experiments and simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Haji-Akbari, Amir; Debenedetti, Pablo G.</p> <p>2017-08-01</p> <p>Surface <span class="hlt">freezing</span> is a phenomenon in which crystallization is enhanced at a vapor-liquid interface. In some systems, such as n-alkanes, this enhancement is dramatic and results in the formation of a crystalline layer at the free interface even at temperatures slightly above the equilibrium bulk <span class="hlt">freezing</span> temperature. There are, however, systems in which the enhancement is purely kinetic and only involves faster nucleation at or near the interface. The first, thermodynamic, type of surface <span class="hlt">freezing</span> is easier to confirm in experiments, requiring only the verification of the existence of crystalline order at the interface. The second, kinetic, type of surface <span class="hlt">freezing</span> is far more difficult to prove experimentally. One material that is suspected of undergoing the second type of surface <span class="hlt">freezing</span> is liquid water. Despite strong indications that the <span class="hlt">freezing</span> of liquid water is kinetically enhanced at vapor-liquid interfaces, the findings are far from conclusive, and the topic remains controversial. In this perspective, we present a simple thermodynamic framework to understand conceptually and distinguish these two types of surface <span class="hlt">freezing</span>. We then briefly survey fifteen years of experimental and computational work aimed at elucidating the surface <span class="hlt">freezing</span> conundrum in water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28240026','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28240026"><span>Thermal <span class="hlt">Gradient</span> During Vacuum-Deposition Dramatically Enhances Charge Transport in Organic Semiconductors: Toward High-Performance N-Type Organic Field-Effect Transistors.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kim, Joo-Hyun; Han, Singu; Jeong, Heejeong; Jang, Hayeong; Baek, Seolhee; Hu, Junbeom; Lee, Myungkyun; Choi, Byungwoo; Lee, Hwa Sung</p> <p>2017-03-22</p> <p>A thermal <span class="hlt">gradient</span> distribution was applied to a substrate during the growth of a vacuum-deposited n-type organic semiconductor (OSC) film prepared from N,N'-bis(2-ethylhexyl)-1,7-dicyanoperylene-3,4:9,10-bis(dicarboxyimide) (PDI-CN2), and the electrical performances of the films deployed in organic field-effect transistors (OFETs) were characterized. The temperature <span class="hlt">gradient</span> at the surface was controlled by tilting the substrate, which varied the temperature one-dimensionally between the heated bottom substrate and the cooled upper substrate. The vacuum-deposited OSC molecules diffused and rearranged on the surface according to the substrate temperature <span class="hlt">gradient</span>, producing directional crystalline and grain structures in the PDI-CN2 film. The morphological and crystalline structures of the PDI-CN2 thin films grown under a <span class="hlt">vertical</span> temperature <span class="hlt">gradient</span> were dramatically enhanced, comparing with the structures obtained from either uniformly heated films or films prepared under a horizontally applied temperature <span class="hlt">gradient</span>. The field effect mobilities of the PDI-CN2-FETs prepared using the <span class="hlt">vertically</span> applied temperature <span class="hlt">gradient</span> were as high as 0.59 cm 2 V -1 s -1 , more than a factor of 2 higher than the mobility of 0.25 cm 2 V -1 s -1 submitted to conventional thermal annealing and the mobility of 0.29 cm 2 V -1 s -1 from the horizontally applied temperature <span class="hlt">gradient</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24825508','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24825508"><span><span class="hlt">Freeze</span> shoe sampler for the collection of hyporheic zone sediments and porewater.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bianchin, M; Smith, L; Beckie, R</p> <p>2015-01-01</p> <p>The Starr and Ingleton (1992) drive point piston sampler (DPPS) design was modified by fitting it with a Murphy and Herkelrath (1996) type sample-<span class="hlt">freezing</span> drive shoe (SFDS), which uses liquid carbon dioxide as a cryogen. Liquid carbon dioxide was used to <span class="hlt">freeze</span> sediments in the lower 0.1 m of the core and the drive-point piston sealed the core at the top preserving the reductive-oxidation (redox) sensitive sediments from the atmosphere and maintaining natural stratigraphy. The use of nitrogen gas to provide positive pressure on the gas system blocked the ingress of water which froze on contact with the cryogen thus blocking the gas lines with ice. With this adaptation to the gas system cores could be collected at greater depths beneath the static water level. This tool was used to collect intact saturated sediment cores from the hyporheic zone of the tidally influenced Fraser River in Vancouver, British Columbia, Canada where steep geochemical and microbial <span class="hlt">gradients</span> develop within the interface between discharging anaerobic groundwater and recharging aerobic river water. In total, 25 cores driven through a 1.5 m sampling interval were collected from the river bed with a mean core recovery of 75%. The ability to deploy this method from a fishing vessel makes the tool more cost effective than traditional marine-based drilling operations which often use barges, tug boats, and drilling rigs. © 2014, National Ground Water Association.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18774169','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18774169"><span>New aspects of boar semen <span class="hlt">freezing</span> strategies.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Grossfeld, R; Sieg, B; Struckmann, C; Frenzel, A; Maxwell, W M C; Rath, D</p> <p>2008-11-01</p> <p>Although cryopreserved boar semen has been available since 1975, a major breakthrough in commercial application has not yet occurred. There is ongoing research to improve sperm survival after thawing, to limit the damage occurring to spermatozoa during <span class="hlt">freezing</span>, and to further minimize the number of spermatozoa needed to establish a pregnancy. Boar spermatozoa are exposed to lipid peroxidation during <span class="hlt">freezing</span> and thawing, which causes damage to the sperm membranes and impairs energy metabolism. The addition of antioxidants or chelating agents (e.g. catalase, vitamin E, glutathione, butylated hydroxytoluene or superoxide dismutase) to the still standard egg-yolk based cooling and <span class="hlt">freezing</span> media for boar semen, effectively prevented this damage. In general, final glycerol concentrations of 2-3% in the <span class="hlt">freezing</span> media, cooling rates of -30 to -50 degrees C/min, and thawing rates of 1200-1800 degrees C/min resulted in the best sperm survival. However, cooling and thawing rates individually optimized for sub-standard <span class="hlt">freezing</span> boars have substantially improved their sperm quality after cryopreservation. With deep intrauterine insemination, the sperm dose has been decreased from 6 to 1x10(9) spermatozoa without compromising farrowing rate or litter size. Minimizing insemination-to-ovulation intervals, based either on estimated or determined ovulation, have also improved the fertility after AI with cryopreserved boar semen. With this combination of different approaches, acceptable fertility with cryopreserved boar semen can be achieved, facilitating the use of cryopreserved boar semen in routine AI programs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110016561','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110016561"><span><span class="hlt">Freeze</span>-Tolerant Condensers</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Crowley, Christopher J.; Elkouhk, Nabil</p> <p>2004-01-01</p> <p>Two condensers designed for use in dissipating heat carried by working fluids feature two-phase, self-adjusting configurations such that their working lengths automatically vary to suit their input power levels and/or heat-sink temperatures. A key advantage of these condensers is that they can function even if the temperatures of their heat sinks fall below the <span class="hlt">freezing</span> temperatures of their working fluids and the fluids <span class="hlt">freeze</span>. The condensers can even be restarted from the frozen condition. The top part of the figure depicts the layout of the first condenser. A two-phase (liquid and vapor) condenser/vapor tube is thermally connected to a heat sink typically, a radiatively or convectively cooled metal panel. A single-phase (liquid) condensate-return tube (return artery) is also thermally connected to the heat sink. At intervals along their lengths, the condenser/vapor tube and the return artery are interconnected through porous plugs. This condenser configuration affords tolerance of <span class="hlt">freezing</span>, variable effective thermal conductance (such that the return temperature remains nearly constant, independently of the ultimate sink temperature), and overall pressure drop smaller than it would be without the porous interconnections. An additional benefit of this configuration is that the condenser can be made to recover from the completely frozen condition either without using heaters, or else with the help of heaters much smaller than would otherwise be needed. The second condenser affords the same advantages and is based on a similar principle, but it has a different configuration that affords improved flow of working fluid, simplified construction, reduced weight, and faster recovery from a frozen condition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17722483','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17722483"><span><span class="hlt">Freeze</span>-drying process monitoring using a cold plasma ionization device.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mayeresse, Y; Veillon, R; Sibille, P H; Nomine, C</p> <p>2007-01-01</p> <p>A cold plasma ionization device has been designed to monitor <span class="hlt">freeze</span>-drying processes in situ by monitoring lyophilization chamber moisture content. This plasma device, which consists of a probe that can be mounted directly on the lyophilization chamber, depends upon the ionization of nitrogen and water molecules using a radiofrequency generator and spectrometric signal collection. The study performed on this probe shows that it is steam sterilizable, simple to integrate, reproducible, and sensitive. The limitations include suitable positioning in the lyophilization chamber, calibration, and signal integration. Sensitivity was evaluated in relation to the quantity of vials and the probe positioning, and correlation with existing methods, such as microbalance, was established. These tests verified signal reproducibility through three <span class="hlt">freeze</span>-drying cycles. Scaling-up studies demonstrated a similar product signature for the same product using pilot-scale and larger-scale equipment. On an industrial scale, the method efficiently monitored the <span class="hlt">freeze</span>-drying cycle, but in a larger industrial <span class="hlt">freeze</span>-dryer the signal was slightly modified. This was mainly due to the positioning of the plasma device, in relation to the vapor flow pathway, which is not necessarily homogeneous within the <span class="hlt">freeze</span>-drying chamber. The plasma tool is a relevant method for monitoring <span class="hlt">freeze</span>-drying processes and may in the future allow the verification of current thermodynamic <span class="hlt">freeze</span>-drying models. This plasma technique may ultimately represent a process analytical technology (PAT) approach for the <span class="hlt">freeze</span>-drying process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/542858-velocity-gradients-reservoir-volumes-lessons-computational-sensitivity','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/542858-velocity-gradients-reservoir-volumes-lessons-computational-sensitivity"><span>Velocity <span class="hlt">gradients</span> and reservoir volumes lessons in computational sensitivity</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Johnson, P.W.</p> <p>1995-12-31</p> <p>The sensitivity of reservoir volume estimation from depth converted geophysical time maps to the velocity <span class="hlt">gradients</span> employed is investigated through a simple model study. The computed volumes are disconcertingly sensitive to <span class="hlt">gradients</span>, both horizontal and <span class="hlt">vertical</span>. The need for an accurate method of time to depth conversion is well demonstrated by the model study in which errors in velocity are magnified 40 fold in the computation of the volume. Thus if +/- 10% accuracy in the volume is desired, we must be able to estimate the velocity at the water contact with 0.25% accuracy. Put another way, if the velocitymore » is 8000 feet per second at the well then we have only +/- 20 feet per second leeway in estimating the velocity at the water contact. Very moderate horizontal and <span class="hlt">vertical</span> <span class="hlt">gradients</span> would typically indicate a velocity change of a few hundred feet per second if they are in the same direction. Clearly the interpreter needs to by very careful. A methodology is demonstrated which takes into account all the information that is available, velocities, tops, depositional and lithologic spatial patterns, and common sense. It is assumed that through appropriate use of check shot and other time-depth information, that the interpreter has correctly tied the reflection picks to the well tops. Such ties are ordinarily too soft for direct time-depth conversion to give adequate depth ties. The proposed method uses a common compaction law as its basis and incorporates time picks, tops and stratigraphic maps into the depth conversion process. The resulting depth map ties the known well tops in an optimum fashion.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017OcMod.116....1E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017OcMod.116....1E"><span>High-order accurate finite-volume formulations for the pressure <span class="hlt">gradient</span> force in layered ocean models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Engwirda, Darren; Kelley, Maxwell; Marshall, John</p> <p>2017-08-01</p> <p>Discretisation of the horizontal pressure <span class="hlt">gradient</span> force in layered ocean models is a challenging task, with non-trivial interactions between the thermodynamics of the fluid and the geometry of the layers often leading to numerical difficulties. We present two new finite-volume schemes for the pressure <span class="hlt">gradient</span> operator designed to address these issues. In each case, the horizontal acceleration is computed as an integration of the contact pressure force that acts along the perimeter of an associated momentum control-volume. A pair of new schemes are developed by exploring different control-volume geometries. Non-linearities in the underlying equation-of-state definitions and thermodynamic profiles are treated using a high-order accurate numerical integration framework, designed to preserve hydrostatic balance in a non-linear manner. Numerical experiments show that the new methods achieve high levels of consistency, maintaining hydrostatic and thermobaric equilibrium in the presence of strongly-sloping layer geometries, non-linear equations-of-state and non-uniform <span class="hlt">vertical</span> stratification profiles. These results suggest that the new pressure <span class="hlt">gradient</span> formulations may be appropriate for general circulation models that employ hybrid <span class="hlt">vertical</span> coordinates and/or terrain-following representations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920062842&hterms=Molecular+Dynamics+Interactions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DMolecular%2BDynamics%2BInteractions','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920062842&hterms=Molecular+Dynamics+Interactions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DMolecular%2BDynamics%2BInteractions"><span>A molecular dynamics study of <span class="hlt">freezing</span> in a confined geometry</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ma, Wen-Jong; Banavar, Jayanth R.; Koplik, Joel</p> <p>1992-01-01</p> <p>The dynamics of <span class="hlt">freezing</span> of a Lennard-Jones liquid in narrow channels bounded by molecular walls is studied by computer simulation. The time development of ordering is quantified and a novel <span class="hlt">freezing</span> mechanism is observed. The liquid forms layers and subsequent in-plane ordering within a layer is accompanied by a sharpening of the layer in the transverse direction. The effects of channel size, the methods of quench, the liquid-wall interaction and the roughness of walls on the <span class="hlt">freezing</span> mechanism are elucidated. Comparison with recent experiments on <span class="hlt">freezing</span> in confined geometries is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120007360','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120007360"><span>Non-Toxic, Low-<span class="hlt">Freezing</span>, Drop-In Replacement Heat Transfer Fluids</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cutbirth, J. Michael</p> <p>2012-01-01</p> <p>A non-toxic, non-flammable, low-<span class="hlt">freezing</span> heat transfer fluid is being developed for drop-in replacement within current and future heat transfer loops currently using water or alcohol-based coolants. Numerous water-soluble compounds were down-selected and screened for toxicological, physical, chemical, compatibility, thermodynamic, and heat transfer properties. Two fluids were developed, one with a <span class="hlt">freezing</span> point near 0 C, and one with a suppressed <span class="hlt">freezing</span> point. Both fluids contain an additive package to improve material compatibility and microbial resistance. The optimized sub-zero solution had a <span class="hlt">freezing</span> point of 30 C, and a <span class="hlt">freezing</span> volume expansion of 10-percent of water. The toxicity of the solutions was experimentally determined as LD(50) greater than 5g/kg. The solutions were found to produce minimal corrosion with materials identified by NASA as potentially existing in secondary cooling loops. Thermal/hydrodynamic performance exceeded that of glycol-based fluids with comparable <span class="hlt">freezing</span> points for temperatures Tf greater than 20 C. The additive package was demonstrated as a buffering agent to compensate for CO2 absorption, and to prevent microbial growth. The optimized solutions were determined to have physically/chemically stable shelf lives for <span class="hlt">freeze</span>/thaw cycles and longterm test loop tests.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26865679','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26865679"><span>New Processes for <span class="hlt">Freeze</span>-Drying in Dual-Chamber Systems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Werk, T; Ludwig, I S; Luemkemann, J; Huwyler, J; Mahler, H-C; Haeuser, C R; Hafner, M</p> <p>2016-01-01</p> <p>Dual-chamber systems can offer self-administration and home care use for lyophilized biologics. Only a few products have been launched in dual-chamber systems so far-presumably due to dual-chamber systems' complex and costly drug product manufacturing process. Within this paper, two improved processes (both based on tray filling technology) for <span class="hlt">freeze</span>-drying pharmaceuticals in dual-chamber systems are described. Challenges with regards to heat transfer were tackled by (1) performing the <span class="hlt">freeze</span>-drying step in a needle-down orientation in combination with an aluminum block, or (2) <span class="hlt">freeze</span>-drying the drug product "externally" in a metal cartridge with subsequent filling of the lyophilized cake into the dual-chamber system. Metal-mediated heat transfer was shown to be efficient in both cases and batch (unit-to-unit) homogeneity with regards to sublimation rate was increased. It was difficult to influence ice crystal size using different methods when in use with an aluminum block due to its heat capacity. Using such a metal carrier implies a large heat capacity leading to relatively small ice crystals. Compared to the established process, drying times were reduced by half using the new processes. The drying time was, however, longer for syringes compared to vials due to the syringe design (long and slim). The differences in drying times were less pronounced for aggressive drying cycles. The proposed processes may help to considerably decrease investment costs into dual-chamber system fill-finish equipment. Dual-chamber syringes offer self-administration and home care use for <span class="hlt">freeze</span>-dried pharmaceuticals. Only a few products have been launched in dual-chamber syringes so far-presumably due to their complex and costly drug product manufacturing process. In this paper two improved processes for <span class="hlt">freeze</span>-drying pharmaceuticals in dual-chamber syringes are described. The major challenge of <span class="hlt">freeze</span>-drying is to transfer heat through a vacuum. The proposed processes cope with this</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JHEP...06..105L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JHEP...06..105L"><span>Step scaling and the Yang-Mills <span class="hlt">gradient</span> flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lüscher, Martin</p> <p>2014-06-01</p> <p>The use of the Yang-Mills <span class="hlt">gradient</span> flow in step-scaling studies of lattice QCD is expected to lead to results of unprecedented precision. Step scaling is usually based on the Schrödinger functional, where time ranges over an interval [0 , T] and all fields satisfy Dirichlet boundary conditions at time 0 and T. In these calculations, potentially important sources of systematic errors are boundary lattice effects and the infamous topology-<span class="hlt">freezing</span> problem. The latter is here shown to be absent if Neumann instead of Dirichlet boundary conditions are imposed on the gauge field at time 0. Moreover, the expectation values of gauge-invariant local fields at positive flow time (and of other well localized observables) that reside in the center of the space-time volume are found to be largely insensitive to the boundary lattice effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4060029','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4060029"><span>Tree mortality from a short-duration <span class="hlt">freezing</span> event and global-change-type drought in a Southwestern piñon-juniper woodland, USA</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2014-01-01</p> <p>This study documents tree mortality in Big Bend National Park in Texas in response to the most acute one-year drought on record, which occurred following a five-day winter <span class="hlt">freeze</span>. I estimated changes in forest stand structure and species composition due to <span class="hlt">freezing</span> and drought in the Chisos Mountains of Big Bend National Park using permanent monitoring plot data. The drought killed over half (63%) of the sampled trees over the entire elevation <span class="hlt">gradient</span>. Significant mortality occurred in trees up to 20 cm diameter (P < 0.05). Pinus cembroides Zucc. experienced the highest seedling and tree mortality (P < 0.0001) (55% of piñon pines died), and over five times as many standing dead pines were observed in 2012 than in 2009. Juniperus deppeana vonSteudal and Quercus emoryi Leibmann also experienced significant declines in tree density (P < 0.02) (30.9% and 20.7%, respectively). Subsequent droughts under climate change will likely cause even greater damage to trees that survived this record drought, especially if such events follow <span class="hlt">freezes</span>. The results from this study highlight the vulnerability of trees in the Southwest to climatic change and that future shifts in forest structure can have large-scale community consequences. PMID:24949231</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27956243','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27956243"><span>Physicochemical characterization of commercial <span class="hlt">freeze</span>-dried snake antivenoms.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Herrera, María; Solano, Daniela; Gómez, Aarón; Villalta, Mauren; Vargas, Mariángela; Sánchez, Andrés; Gutiérrez, José María; León, Guillermo</p> <p>2017-02-01</p> <p><span class="hlt">Freeze</span>-drying is a process used to improve the stability of pharmaceutical proteins, including snake antivenoms. This additional step confers these with a higher stability in comparison to liquid formulations, especially in tropical regions where high temperatures could affect the activity of immunoglobulins. Currently, the knowledge about <span class="hlt">freeze</span>-drying process conditions for snake antivenoms is very limited. Some of the scarce scientific works on this subject reported reconstitution times up to 90 min for these preparations, which could imply a delay in the beginning of the antivenom therapy at the clinical setting. Therefore there is a reasonable concern about whether <span class="hlt">freeze</span>-dried antivenoms exhibit the desired attributes for solid pharmaceutical proteins. In this work, a physicochemical characterization of seven commercial <span class="hlt">freeze</span>-dried snake antivenoms was performed based on tests recommended by the World Health Organization (WHO). No significant differences were observed between the products regarding macroscopic appearance of the solid cakes, reconstitution times, residual humidity and monomers content. On the other hand, total protein concentration, turbidity and electrophoretic profile were different among samples. Microscopic analysis by scanning electron microscopy showed no collapsed structure and, instead, most of the samples showed a characteristic protein morphology composed of smooth plates and channels. All the parameters tested in this study were according to literature recommendations and evidenced that, in spite of slight variations found for some products, formulation and <span class="hlt">freeze</span>-drying conditions chosen by manufacturers are adequate to prevent aggregation and generate, in physicochemical terms, <span class="hlt">freeze</span>-dried antivenoms of acceptable quality. Copyright © 2016 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28486656','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28486656"><span>Canopy <span class="hlt">gradients</span> in leaf functional traits for species that differ in growth strategies and shade tolerance.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Coble, Adam P; Fogel, Marilyn L; Parker, Geoffrey G</p> <p>2017-10-01</p> <p>In temperate deciduous forests, <span class="hlt">vertical</span> <span class="hlt">gradients</span> in leaf mass per area (LMA) and area-based leaf nitrogen (Narea) are strongly controlled by <span class="hlt">gradients</span> in light availability. While there is evidence that hydrostatic constraints on leaf development may diminish LMA and Narea responses to light, inherent differences among tree species may also influence leaf developmental and morphological response to light. We investigated <span class="hlt">vertical</span> <span class="hlt">gradients</span> in LMA, Narea and leaf carbon isotope composition (δ13C) for three temperate deciduous species (Carpinus caroliniana Walter, Fagus grandifolia Ehrh., Liriodendron tulipifera L.) that differed in growth strategy (e.g., indeterminate and determinate growth), shade tolerance and leaf area to sapwood ratio (Al:As). Leaves were sampled across a broad range of light conditions within three <span class="hlt">vertical</span> layers of tree crowns to maximize variation in light availability at each height and to minimize collinearity between light and height. All species displayed similar responses to light with respect to Narea and δ13C, but not for LMA. Light was more important for <span class="hlt">gradients</span> in LMA for the shade-tolerant (C. caroliniana) and -intolerant (L. tulipifera) species with indeterminate growth, and height (e.g., hydrostatic <span class="hlt">gradients</span>) and light were equally important for the shade-tolerant (F. grandifolia) species with determinate growth. Fagus grandifolia had a higher morphological plasticity in response to light, which may offer a competitive advantage in occupying a broader range of light conditions throughout the canopy. Differences in responses to light and height for the taller tree species, L. tulipifera and F. grandifolia, may be attributed to differences in growth strategy or Al:As, which may alter morphological and functional responses to light availability. While height was important in F. grandifolia, height was no more robust in predicting LMA than light in any of the species, confirming the strong role of light availability in</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22576810','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22576810"><span>Mutagenic effect of <span class="hlt">freezing</span> on nuclear DNA of Saccharomyces cerevisiae.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Todorova, T; Pesheva, M; Stamenova, R; Dimitrov, M; Venkov, P</p> <p>2012-05-01</p> <p>Although fragmentation of DNA has been observed in cells undergoing <span class="hlt">freezing</span> procedures, a mutagenic effect of sub-zero temperature treatment has not been proved by induction and isolation of mutants in nuclear DNA (nDNA). In this communication we supply evidence for mutagenicity of <span class="hlt">freezing</span> on nDNA of Saccharomyces cerevisiae cells. In the absence of cryoprotectors, cooling for 2 h at +4°C and <span class="hlt">freezing</span> for 1 h at -10°C and 16 h at -20°C, with a cooling rate of 3°C/min, resulted in induction of frame-shift and reverse mutations in microsatellite and coding regions of nDNA. The sub-zero temperature exposure also has a strong recombinogenic effect, evidenced by induction of gene-conversion and crossing-over events. <span class="hlt">Freezing</span> induces mutations and enhances recombination with a frequency equal to or higher than that of methylmethanesulphonate at comparable survival rates. The signals for the appearance of nDNA lesions induced by <span class="hlt">freezing</span> are detected and transduced by the DNA damage pathway. Extracellular cryoprotectors did not prevent the mutagenic effect of <span class="hlt">freezing</span>, while accumulation of trehalose inside cells reduced nDNA cryodamage. <span class="hlt">Freezing</span> of cells is accompanied by generation of high ROS levels, and the oxidative stress raised during the <span class="hlt">freeze</span>-thaw process is the most likely reason for the DNA damaging effect. Experiments with mitochondrial rho⁻ mutants or scavengers of ROS indicated that mutagenic and recombinogenic effects of sub-zero temperatures can be decreased but not eliminated by reduction of ROS level. The complete protection against cryodamage in nDNA required simultaneous usage of intracellular cryoprotector and ROS scavenger during the <span class="hlt">freeze</span>-thaw process. Copyright © 2012 John Wiley & Sons, Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title7-vol5/pdf/CFR-2012-title7-vol5-sec305-7.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title7-vol5/pdf/CFR-2012-title7-vol5-sec305-7.pdf"><span>7 CFR 305.7 - Quick <span class="hlt">freeze</span> treatment requirements.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-01-01</p> <p>... 7 Agriculture 5 2012-01-01 2012-01-01 false Quick <span class="hlt">freeze</span> treatment requirements. 305.7 Section 305.7 Agriculture Regulations of the Department of Agriculture (Continued) ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE PHYTOSANITARY TREATMENTS § 305.7 Quick <span class="hlt">freeze</span> treatment...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29892104','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29892104"><span>Effects of different <span class="hlt">freezing</span> methods on calcium enriched papaya (Carica papaya L.).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lovera, Nancy N; Ramallo, Laura; Salvadori, Viviana O</p> <p>2018-06-01</p> <p>The effect of calcium impregnation on drip loss, colour, mechanical properties, sensory perception and <span class="hlt">freezing</span> time on frozen-thawed papaya was studied, evaluating different <span class="hlt">freezing</span> methods: cryogenic, tunnel and household freezer <span class="hlt">freezing</span>. Osmotic dehydration as pre-treatment was also evaluated. <span class="hlt">Freezing</span> in liquid nitrogen was considered an inappropriate method for papaya preservation due to cracking. Calcium impregnation and osmotic dehydration increased tissue firmness and decreased <span class="hlt">freezing</span> time (<span class="hlt">freezing</span> time for fresh, calcium impregnated and osmo-dehydrated fruit was 23, 17 and 5 min in a tunnel and 118, 83 and 60 min in a household freezer, respectively). Calcium lactate was the most effective way to protect tissue's firmness before and after a <span class="hlt">freeze</span>-thaw cycle (maximum stress values approx. 300-400% of the raw tissue for tunnel <span class="hlt">freezing</span> and 260% for household freezer). Microstructure analysis showed better tissue integrity retention in papaya samples impregnated with calcium lactate than in those with calcium gluconate, after a <span class="hlt">freezing</span>-thawing cycle, in agreement with the drip loss results. In spite of these results, consumers preferred frozen papaya without pre-treatment or impregnated with calcium gluconate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MS%26E..278a2126V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MS%26E..278a2126V"><span>A tissue snap-<span class="hlt">freezing</span> apparatus without sacrificial cryogens</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vanapalli, Srinivas; Jagga, Sahil; Holland, Harry; ter Brake, Marcel</p> <p>2017-12-01</p> <p>Molecular technologies in cancer diagnosis require a fresh and frozen tissue, which is obtained by means of snap-<span class="hlt">freezing</span>. Currently, coolants such as solid carbon dioxide and liquid nitrogen are used to preserve good morphology of the tissue. Using these coolants, snap <span class="hlt">freezing</span> of tissues for diagnostic and research purposes is often time consuming, laborious, even hazardous and not user friendly. For that reason snap-<span class="hlt">freezing</span> is not routinely applied at the location of biopsy acquisition. Furthermore, the influence of optimal cooling rate and cold sink temperature on the viability of the cells is not well known. In this paper, a snap-<span class="hlt">freezing</span> apparatus powered by a small cryocooler is presented that will allow bio-medical research of tissue <span class="hlt">freezing</span> methods and is safe to use in a hospital. To benchmark this apparatus, cooldown of a standard aluminum cryo-vial in liquid nitrogen is measured and the cooling rate is about -25 K/s between 295 K and 120 K. Sufficient cooling rate is obtained by a forced convective helium gas flow through a gap formed between the cryo-vial and a cold surface and is therefore chosen as the preferred cooling method. A conceptual design of the snap-apparatus with forced flow is discussed in this paper.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14499200','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14499200"><span>Wheeled and standard walkers in Parkinson's disease patients with gait <span class="hlt">freezing</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cubo, Esther; Moore, Charity G; Leurgans, Sue; Goetz, Christopher G</p> <p>2003-10-01</p> <p>Compare the efficacy of two walking assistance devices (wheeled walker and standard walker) to unassisted walking for patients with PD and gait <span class="hlt">freezing</span>. Although numerous walking devices are used clinically, their relative effects on <span class="hlt">freezing</span> and walking speed have never been systematically tested. Nineteen PD patients (14 non-demented) walked under three conditions in randomized order: unassisted walking, standard walker, and wheeled walker. Patients walked up to three times in each condition through a standard course that included rising from a chair, walking through a doorway, straightway walking, pivoting, and return. Total walking time, <span class="hlt">freezing</span> time and number of <span class="hlt">freezes</span> were compared for the three conditions using mixed models (walking time) and Friedman's test (<span class="hlt">freezing</span>). The wheeled walker was further studied by comparing the effect of an attached laser that projected a bar of light on the floor as a visual walking cue. Use of either type of device significantly slowed walking compared to unassisted walking. Neither walker reduced any index of <span class="hlt">freezing</span>, nor the laser attachment offered any advantage to the wheeled walker. The standard walker increased <span class="hlt">freezing</span>, and the wheeled walker had no effect on <span class="hlt">freezing</span>. Among the non-demented subjects (n=14), the same patterns occurred, although the walking speed was less impaired by the wheeled walker than the standard walker in this group. Though walkers may stabilize patients and increase confidence, PD patients walk more slowly when using them, without reducing <span class="hlt">freezing</span>. Because the wheeled walker was intermediate for walking time and does not aggravate <span class="hlt">freezing</span>, if walkers are used for these subjects, this type of walker should be favored.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22248916','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22248916"><span>Cold tolerance and <span class="hlt">freeze</span>-induced glucose accumulation in three terrestrial slugs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Slotsbo, Stine; Hansen, Lars Monrad; Jordaens, Kurt; Backeljau, Thierry; Malmendal, Anders; Nielsen, Niels Chr; Holmstrup, Martin</p> <p>2012-04-01</p> <p>Cold tolerance and metabolic responses to <span class="hlt">freezing</span> of three slug species common in Scandinavia (Arion ater, Arion rufus and Arion lusitanicus) are reported. Autumn collected slugs were cold acclimated in the laboratory and subjected to <span class="hlt">freezing</span> conditions simulating likely winter temperatures in their habitat. Slugs spontaneously froze at about -4 °C when cooled under dry conditions, but <span class="hlt">freezing</span> of body fluids was readily induced at -1 °C when in contact with external ice crystals. All three species survived <span class="hlt">freezing</span> for 2 days at -1 °C, and some A. rufus and A. lusitanicus also survived <span class="hlt">freezing</span> at -2 °C. (1)H NMR spectroscopy revealed that <span class="hlt">freezing</span> of body fluids resulted in accumulation of lactate, succinate and glucose. Accumulation of lactate and succinate indicates that ATP production occurred via fermentative pathways, which is likely a result of oxygen depletion in frozen tissues. Glucose increased from about 6 to 22 μg/mg dry tissue upon <span class="hlt">freezing</span> in A. rufus, but less so in A. ater and A. lusitanicus. Glucose may thus act as a cryoprotectant in these slugs, although the concentrations are not as high as reported for other <span class="hlt">freeze</span> tolerant invertebrates. Copyright © 2012 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006MMTB...37..929V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006MMTB...37..929V"><span>Water-cooled probe technique for the study of <span class="hlt">freeze</span> lining formation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Verscheure, Karel; Campforts, Mieke; Verhaeghe, Frederik; Boydens, Eddy; Blanpain, Bart; Wollants, Patrick; van Camp, Maurits</p> <p>2006-12-01</p> <p>Furnace protection by water-cooled <span class="hlt">freeze</span> linings becomes increasingly important as the metal producing industry attempts to achieve higher process intensities. Systematic investigations of the growth and the resulting microstructure and compositional profile of <span class="hlt">freeze</span> linings are necessary to understand the behavior of <span class="hlt">freeze</span> linings, their relation with the industrial process, and their interaction with the wall cooling system. We have developed a technique based on the submergence of a water-cooled probe into a liquid slag bath. <span class="hlt">Freeze</span> linings of two industrial nonferrous slags have been produced using this technique and their growth, microstructural, and compositional profiles as a function of submergence time were determined. Thermodynamic equilibrium for the investigated slag systems was calculated and compared with the observed microstructures. The <span class="hlt">freeze</span> linings form in approximately 15 minutes. Close to the water cooling, the <span class="hlt">freeze</span> linings are predominantly amorphous in structure. With increasing distance from the water cooling, the proportion of crystalline phases increases and bath material is entrapped in the microstructure. Cellular crystals are observed close to the bath. The <span class="hlt">freeze</span> linings exhibit an approximate homogeneous composition. The results demonstrate that the technique is a successful tool in obtaining information on the growth, microstructure, and composition of <span class="hlt">freeze</span> linings in industrial water-cooled furnaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21347620','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21347620"><span>Emerging <span class="hlt">freeze</span>-drying process development and scale-up issues.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Patel, Sajal Manubhai; Pikal, Michael J</p> <p>2011-03-01</p> <p>Although several guidelines do exist for <span class="hlt">freeze</span>-drying process development and scale-up, there are still a number of issues that require additional attention. The objective of this review article is to discuss some emerging process development and scale-up issue with emphasis on effect of load condition and <span class="hlt">freeze</span>-drying in novel container systems such as syringes, Lyoguard trays, ampoules, and 96-well plates. Understanding the heat and mass transfer under different load conditions and for <span class="hlt">freeze</span>-drying in these novel container systems will help in developing a robust <span class="hlt">freeze</span>-drying process which is also easier to scale-up. Further research and development needs in these emerging areas have also been addressed. © 2011 American Association of Pharmaceutical Scientists</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870040112&hterms=Flow+Diagram&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DFlow%2BDiagram','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870040112&hterms=Flow+Diagram&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DFlow%2BDiagram"><span>Flow regimes in a shallow rotating cylindrical annulus with temperature <span class="hlt">gradients</span> imposed on the horizontal boundaries</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hathaway, D. H.; Fowlis, W. W.</p> <p>1986-01-01</p> <p>Experimental flow regime diagrams are determined for a new rotating cylindrical annulus configuration which permits a measure of control over the internal <span class="hlt">vertical</span> temperature <span class="hlt">gradient</span>. The new annulus has radial temperature <span class="hlt">gradients</span> imposed on plane horizontal thermally conducting endwalls (with the cylindrical sidewalls as insulators) and is considered to be more relevant to atmospheric dynamics studies than the classical cylindrical annulus. Observations have revealed that, in addition to the axisymmetric flow and nonaxisymmetric baroclinic wave flow which occur in the classical annulus, two additional nonaxisymmetric flow types occur in the new annulus: boundary-layer thermal convection and deep thermal convection. Flow regime diagrams for three different values of the imposed <span class="hlt">vertical</span> temperature difference are presented, and explanations for the flow transitions are offered. The new annulus provides scientific backup for the proposed Atmospheric General Circulation Experiment for Spacelab. The apparatus diagram is included.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PEPS....5...29L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PEPS....5...29L"><span><span class="hlt">Vertical</span> structure of the lower troposphere derived from MU radar, unmanned aerial vehicle, and balloon measurements during ShUREX 2015</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Luce, Hubert; Kantha, Lakshmi; Hashiguchi, Hiroyuki; Lawrence, Dale; Mixa, Tyler; Yabuki, Masanori; Tsuda, Toshitaka</p> <p>2018-12-01</p> <p>The ShUREX (Shigaraki UAV Radar Experiment) 2015 campaign carried out at the Shigaraki Middle and Upper atmosphere (MU) observatory (Japan) in June 2015 provided a unique opportunity to compare <span class="hlt">vertical</span> profiles of atmospheric parameters estimated from unmanned aerial vehicle (UAV), balloon, and radar data in the lower troposphere. The present work is intended primarily as a demonstration of the potential offered by combination of these three instruments for studying the small-scale structure and dynamics in the lower troposphere. Here, we focus on data collected almost simultaneously by two instrumented UAVs and two meteorological balloons, near the MU radar operated continuously during the campaign. The UAVs flew along helical ascending and descending paths at a nearly constant horizontal distance from the radar ( 1.0 km), while the balloons launched from the MU radar site drifted up to 3-5 km in the altitude range of comparisons ( 0.5 to 4.0 km) due to wind advection. <span class="hlt">Vertical</span> profiles of squared Brünt-Väisälä frequency N 2 and squared <span class="hlt">vertical</span> <span class="hlt">gradient</span> of generalized potential refractive index M 2 were estimated at a <span class="hlt">vertical</span> resolution of 20 m from pressure, temperature, and humidity data collected by UAVs and radiosondes. Profiles of M 2 were also estimated from MU radar echo power at <span class="hlt">vertical</span> incidence at a <span class="hlt">vertical</span> sampling of 20 m and various time resolutions (1-4 min). The balloons and the MU radar provided <span class="hlt">vertical</span> profiles of wind and wind shear S so that two independent estimates of the <span class="hlt">gradient</span> Richardson number ( Ri = N 2/ S 2) could be obtained at a range resolution of 150 m. The two estimates of Ri profiles also showed remarkable agreement at all altitudes. We show that all three instruments detected the same prominent temperature and humidity <span class="hlt">gradients</span>, down to decameter scales in stratified conditions. These <span class="hlt">gradients</span> extended horizontally over a few kilometers at least and persisted for hours without significant changes, indicating that the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003SPIE.5009..153H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003SPIE.5009..153H"><span>Visualizing multiattribute Web transactions using a <span class="hlt">freeze</span> technique</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hao, Ming C.; Cotting, Daniel; Dayal, Umeshwar; Machiraju, Vijay; Garg, Pankaj</p> <p>2003-05-01</p> <p>Web transactions are multidimensional and have a number of attributes: client, URL, response times, and numbers of messages. One of the key questions is how to simultaneously lay out in a graph the multiple relationships, such as the relationships between the web client response times and URLs in a web access application. In this paper, we describe a <span class="hlt">freeze</span> technique to enhance a physics-based visualization system for web transactions. The idea is to <span class="hlt">freeze</span> one set of objects before laying out the next set of objects during the construction of the graph. As a result, we substantially reduce the force computation time. This technique consists of three steps: automated classification, a <span class="hlt">freeze</span> operation, and a graph layout. These three steps are iterated until the final graph is generated. This iterated-<span class="hlt">freeze</span> technique has been prototyped in several e-service applications at Hewlett Packard Laboratories. It has been used to visually analyze large volumes of service and sales transactions at online web sites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19810068862','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19810068862"><span>Photomicrographic Investigation of Spontaneous <span class="hlt">Freezing</span> Temperatures of Supercooled Water Droplets</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dorsch, R. G.; Hacker, P. T.</p> <p>1950-01-01</p> <p>A photomicrographic technique for investigating eupercooled. water droplets has been devised and. used. to determine the spontaneous <span class="hlt">freezing</span> temperatures of eupercooled. water droplets of the size ordinarily found. in the atmosphere. The <span class="hlt">freezing</span> temperatures of 4527 droplets ranging from 8.75 to 1000 microns in diameter supported on a platinum surface and 571 droplets supported on copper were obtained. The average spontaneous <span class="hlt">freezing</span> temperature decreased with decrease in the size of the droplets. The effect of size on the spontaneous <span class="hlt">freezing</span> temperature was particularly marked below 60 microns. Frequency-distribution curves of the spontaneous <span class="hlt">freezing</span> temperatures observed for droplets of a given size were obtained. Although no droplet froze at a temperature above 20 0 F, all droplets melted at 32 F. Results obtained with a copper support did not differ essentially from those obtained with a platinum surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4166714','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4166714"><span>Independent control of differently-polarized waves using anisotropic <span class="hlt">gradient</span>-index metamaterials</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ma, Hui Feng; Wang, Gui Zhen; Jiang, Wei Xiang; Cui, Tie Jun</p> <p>2014-01-01</p> <p>We propose a kind of anisotropic <span class="hlt">gradient</span>-index (GRIN) metamaterials, which can be used to control differently-polarized waves independently. We show that two three- dimensional (3D) planar lenses made of such anisotropic GRIN metamaterials are able to make arbitrary beam deflections for the <span class="hlt">vertical</span> (or horizontal) polarization but have no response to the horizontal (or <span class="hlt">vertical</span>) polarization. Then the <span class="hlt">vertically</span>- and horizontally-polarized waves are separated and controlled independently to deflect to arbitrarily different directions by designing the anisotropic GRIN planar lenses. We make experimental verifications of the lenses using such a special metamaterial, which has both electric and magnetic responses simultaneously to reach approximately equal permittivity and permeability. Hence excellent impedance matching is obtained between the GRIN planar lenses and the air. The measurement results demonstrate good performance on the independent controls of differently-polarized waves, as observed in the numerical simulations. PMID:25231412</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23681564','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23681564"><span>Accurate prediction of collapse temperature using optical coherence tomography-based <span class="hlt">freeze</span>-drying microscopy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Greco, Kristyn; Mujat, Mircea; Galbally-Kinney, Kristin L; Hammer, Daniel X; Ferguson, R Daniel; Iftimia, Nicusor; Mulhall, Phillip; Sharma, Puneet; Kessler, William J; Pikal, Michael J</p> <p>2013-06-01</p> <p>The objective of this study was to assess the feasibility of developing and applying a laboratory tool that can provide three-dimensional product structural information during <span class="hlt">freeze</span>-drying and which can accurately characterize the collapse temperature (Tc ) of pharmaceutical formulations designed for <span class="hlt">freeze</span>-drying. A single-vial <span class="hlt">freeze</span> dryer coupled with optical coherence tomography <span class="hlt">freeze</span>-drying microscopy (OCT-FDM) was developed to investigate the structure and Tc of formulations in pharmaceutically relevant products containers (i.e., <span class="hlt">freeze</span>-drying in vials). OCT-FDM was used to measure the Tc and eutectic melt of three formulations in <span class="hlt">freeze</span>-drying vials. The Tc as measured by OCT-FDM was found to be predictive of <span class="hlt">freeze</span>-drying with a batch of vials in a conventional laboratory <span class="hlt">freeze</span> dryer. The <span class="hlt">freeze</span>-drying cycles developed using OCT-FDM data, as compared with traditional light transmission <span class="hlt">freeze</span>-drying microscopy (LT-FDM), resulted in a significant reduction in primary drying time, which could result in a substantial reduction of manufacturing costs while maintaining product quality. OCT-FDM provides quantitative data to justify <span class="hlt">freeze</span>-drying at temperatures higher than the Tc measured by LT-FDM and provides a reliable upper limit to setting a product temperature in primary drying. Copyright © 2013 Wiley Periodicals, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSPO14D2844S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPO14D2844S"><span>Sub-diurnal Variation of SST <span class="hlt">Gradients</span> in Infrared Satellite Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Salter, J. P.; Cornillon, P. C.; Clayson, C. A.</p> <p>2016-02-01</p> <p>Ocean fronts are known to influence many physical, biological, and chemical processes including ocean mixing, air-sea interaction, cloud and wind patterns, and marine productivity. Satellite-derived Sea Surface Temperature (SST) measurements are an invaluable tool in studying ocean fronts because of the large spatial and temporal coverage of satellite data, extending back as far as the early 1980s. One of the limitations to satellite-derived ocean fronts is that they provide no information about the underlying <span class="hlt">vertical</span> structure; furthermore, the dynamics on sub-diurnal time scales for ocean fronts are poorly understood. In this poster we examine the daily signal of SST <span class="hlt">gradient</span> magnitudes for the eastern Mediterranean sea as the first step in quantifying a subset of ocean fronts globally and how they vary on sub-diurnal time scales. We find that mean <span class="hlt">gradient</span> magnitude in summer months increases and peaks around 2-4 PM Local Sun Time (LST). We find that the peak in summer months results from an increase in the magnitude of weaker <span class="hlt">gradients</span> while the magnitude of the strongest <span class="hlt">gradients</span> decrease; however, the weaker <span class="hlt">gradients</span> contribute more strongly to the mean signal, resulting in the increase. The mid-afternoon peak in SST <span class="hlt">gradient</span> magnitude disappears in winter with only a suggestion of a peak earlier in the day although the paucity of cloud free data in winter precludes making a statistically significant statement in this regard.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11425939','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11425939"><span><span class="hlt">Freezing</span> of gait in PD: prospective assessment in the DATATOP cohort.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Giladi, N; McDermott, M P; Fahn, S; Przedborski, S; Jankovic, J; Stern, M; Tanner, C</p> <p>2001-06-26</p> <p>To study the development of <span class="hlt">freezing</span> of gait in PD. <span class="hlt">Freezing</span> of gait is a common, disabling, and poorly understood symptom in PD. The authors analyzed data from 800 patients with early PD from the Deprenyl and Tocopherol Antioxidative Therapy of Parkinsonism (DATATOP) clinical trial who were assigned either placebo, deprenyl, tocopherol, or the combination of deprenyl and tocopherol. The primary outcome measure was the time from randomization until the <span class="hlt">freezing</span> of gait score on the Unified Parkinson's Disease Rating Scale (UPDRS) became positive. Fifty-seven patients (7.1%) had <span class="hlt">freezing</span> of gait at study entry and 193 (26%) of the remaining patients experienced the symptom by the end of the follow-up period. Those with <span class="hlt">freezing</span> of gait at baseline had significantly more advanced disease than those without the symptom, as measured by total UPDRS and Hoehn and Yahr stage. High baseline risk factors for developing <span class="hlt">freezing</span> of gait during the follow-up period were the onset of PD with a gait disorder; higher scores of rigidity, postural instability, bradykinesia and speech; and longer disease duration. In contrast, tremor was strongly associated with a decreased risk for <span class="hlt">freezing</span> of gait. At the end of follow-up, the signs most strongly associated with the <span class="hlt">freezing</span> phenomenon were gait, balance, and speech disorders, not rigidity or bradykinesia. Deprenyl treatment was strongly associated with a decreased risk for developing <span class="hlt">freezing</span> of gait; tocopherol had no effect. <span class="hlt">Freezing</span> of gait is directly related to duration of PD. Risk factors at onset of disease are the absence of tremor and PD beginning as a gait disorder. The development of <span class="hlt">freezing</span> of gait in the course of the illness is strongly associated with the development of balance and speech problems, less so with the worsening of bradykinesia, and is not associated with the progression of rigidity. These results support the concept that the <span class="hlt">freezing</span> phenomenon is distinct from bradykinesia. Deprenyl, in the absence</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10752582','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10752582"><span>"On" <span class="hlt">freezing</span> in Parkinson's disease: resistance to visual cue walking devices.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kompoliti, K; Goetz, C G; Leurgans, S; Morrissey, M; Siegel, I M</p> <p>2000-03-01</p> <p>To measure "on" <span class="hlt">freezing</span> during unassisted walking (UW) and test if two devices, a modified inverted stick (MIS) and a visual laser beam stick (LBS) improved walking speed and number of "on" <span class="hlt">freezing</span> episodes in patients with Parkinson's disease (PD). Multiple visual cues can overcome "off' <span class="hlt">freezing</span> episodes and can be useful in improving gait function in parkinsonian patients. These devices have not been specifically tested in "on" <span class="hlt">freezing</span>, which is unresponsive to pharmacologic manipulations. Patients with PD, motor fluctuations and <span class="hlt">freezing</span> while "on," attempted walking on a 60-ft track with each of three walking conditions in a randomized order: UW, MIS, and LBS. Total time to complete a trial, number of <span class="hlt">freezes</span>, and the ratio of walking time to the number of <span class="hlt">freezes</span> were compared using Friedman's test. Twenty-eight patients with PD, mean age 67.81 years (standard deviation [SD] 7.54), mean disease duration 13.04 years (SD 7.49), and mean motor Unified Parkinson's Disease Rating Scale score "on" 32.59 (SD 10.93), participated in the study. There was a statistically significant correlation of time needed to complete a trial and number of <span class="hlt">freezes</span> for all three conditions (Spearman correlations: UW 0.973, LBS 0.0.930, and MIS 0.842). The median number of <span class="hlt">freezes</span>, median time to walk in each condition, and median walking time per <span class="hlt">freeze</span> were not significantly different in pairwise comparisons of the three conditions (Friedman's test). Of the 28 subjects, six showed improvement with the MIS and six with the LBS in at least one outcome measure. Assisting devices, specifically based on visual cues, are not consistently beneficial in overcoming "on" <span class="hlt">freezing</span> in most patients with PD. Because this is an otherwise untreatable clinical problem and because occasional subjects do respond, cautious trials of such devices under the supervision of a health professional should be conducted to identify those patients who might benefit from their long-term use.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3722352','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3722352"><span>Asymmetric pedunculopontine network connectivity in parkinsonian patients with <span class="hlt">freezing</span> of gait</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Fling, Brett W.; Cohen, Rajal G.; Mancini, Martina; Nutt, John G.; Fair, Damian A.</p> <p>2013-01-01</p> <p><span class="hlt">Freezing</span> of gait is one of the most debilitating symptoms in Parkinson’s disease as it causes falls and reduces mobility and quality of life. The pedunculopontine nucleus is one of the major nuclei of the mesencephalic locomotor region and has neurons related to anticipatory postural adjustments preceding step initiation as well as to the step itself, thus it may be critical for coupling posture and gait to avoid <span class="hlt">freezing</span>. Because <span class="hlt">freezing</span> of gait and postural impairments have been related to frontal lesions and frontal dysfunction such as executive function, we hypothesized that <span class="hlt">freezing</span> is associated with disrupted connectivity between midbrain locomotor regions and medial frontal cortex. We used diffusion tensor imaging to quantify structural connectivity of the pedunculopontine nucleus in patients with Parkinson’s disease with <span class="hlt">freezing</span> of gait, without <span class="hlt">freezing</span>, and healthy age-matched controls. We also included behavioural tasks to gauge severity of <span class="hlt">freezing</span> of gait, quantify gait metrics, and assess executive cognitive functions to determine whether between-group differences in executive dysfunction were related to pedunculopontine nucleus structural network connectivity. Using seed regions from the pedunculopontine nucleus, we were able to delineate white matter connections between the spinal cord, cerebellum, pedunculopontine nucleus, subcortical and frontal/prefrontal cortical regions. The current study is the first to demonstrate differences in structural connectivity of the identified locomotor pathway in patients with <span class="hlt">freezing</span> of gait. We report reduced connectivity of the pedunculopontine nucleus with the cerebellum, thalamus and multiple regions of the frontal cortex. Moreover, these structural differences were observed solely in the right hemisphere of patients with <span class="hlt">freezing</span> of gait. Finally, we show that the more left hemisphere-lateralized the pedunculopontine nucleus tract volume, the poorer the performance on cognitive tasks requiring the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23598062','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23598062"><span>B1 transmit phase <span class="hlt">gradient</span> coil for single-axis TRASE RF encoding.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Deng, Qunli; King, Scott B; Volotovskyy, Vyacheslav; Tomanek, Boguslaw; Sharp, Jonathan C</p> <p>2013-07-01</p> <p>TRASE (Transmit Array Spatial Encoding) MRI uses RF transmit phase <span class="hlt">gradients</span> instead of B0 field <span class="hlt">gradients</span> for k-space traversal and high-resolution MR image formation. Transmit coil performance is a key determinant of TRASE image quality. The purpose of this work is to design an optimized RF transmit phase <span class="hlt">gradient</span> array for spatial encoding in a transverse direction (x- or y- axis) for a 0.2T <span class="hlt">vertical</span> B0 field MRI system, using a single transmitter channel. This requires the generation of two transmit B1 RF fields with uniform amplitude and positive and negative linear phase <span class="hlt">gradients</span> respectively over the imaging volume. A two-element array consisting of a double Maxwell-type coil and a Helmholtz-type coil was designed using 3D field simulations. The phase <span class="hlt">gradient</span> polarity is set by the relative phase of the RF signals driving the simultaneously energized elements. Field mapping and 1D TRASE imaging experiments confirmed that the constructed coil produced the fields and operated as designed. A substantially larger imaging volume relative to that obtainable from a non-optimized Maxwell-Helmholtz design was achieved. The Maxwell (sine)-Helmholtz (cosine) approach has proven successful for a horizontal phase <span class="hlt">gradient</span> coil. A similar approach may be useful for other phase-<span class="hlt">gradient</span> coil designs. Copyright © 2013 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1982crre.proc..269R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1982crre.proc..269R"><span>Frost heave susceptibility of saturated soil under constant rate of <span class="hlt">freezing</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ryokai, K.; Iguro, M.; Yoneyama, K.</p> <p></p> <p>Introduced are the results of experiments carried out to quantitatively obtain the frost heave pressure and displacement of soil subjected to artificial <span class="hlt">freezing</span> or <span class="hlt">freezing</span> around in-ground liquefied natural gas storage tanks. This experiment is conducted to evaluate the frost heave susceptibility of saturated soil under overconsolidation. In other words, this experiment was carried out to obtain the relation of the over-burden pressure and <span class="hlt">freezing</span> rate to the frost heave ratio by observing the frost heave displacement and <span class="hlt">freezing</span> time of specimens by <span class="hlt">freezing</span> the specimens at a constant <span class="hlt">freezing</span> rate under a constant overburden pressure, while letting water freely flow in and out of the system. Introduced are the procedures for frost heave test required to quantitatively obtain the frost heave displacement and pressure of soil. Furthermore, the relation between the frost heave susceptibility and physical properties of soil obtained by this test is reported.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ApPhB.116..533J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ApPhB.116..533J"><span>Immersion transmission ellipsometry (ITE) for the determination of orientation <span class="hlt">gradients</span> in photoalignment layers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jung, C. C.; Stumpe, J.</p> <p>2014-09-01</p> <p>The capability of the method of immersion transmission ellipsometry (ITE) (Jung et al. Int Patent WO, 2004/109260) to not only determine three-dimensional refractive indices in anisotropic thin films (which was already possible in the past), but even their <span class="hlt">gradients</span> along the z-direction (perpendicular to the film plane) is investigated in this paper. It is shown that the determination of orientation <span class="hlt">gradients</span> in deep-sub-μm films becomes possible by applying ITE in combination with reflection ellipsometry. The technique is supplemented by atomic force microscopy for measuring the film thickness. For a photo-oriented thin film, no <span class="hlt">gradient</span> was found, as expected. For a photo-oriented film, which was subsequently annealed in a nematic liquid crystalline phase, an order was found similar to the one applied in <span class="hlt">vertically</span> aligned nematic displays, with a tilt angle varying along the z-direction. For fresh films, <span class="hlt">gradients</span> were only detected for the refractive index perpendicular to the film plane, as expected.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24815419','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24815419"><span><span class="hlt">Freezing</span> of gait in Parkinson's disease: the paradoxical interplay between gait and cognition.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ricciardi, Lucia; Bloem, Bastiaan R; Snijders, Anke H; Daniele, Antonio; Quaranta, Davide; Bentivoglio, Anna Rita; Fasano, Alfonso</p> <p>2014-08-01</p> <p><span class="hlt">Freezing</span> of gait is a disabling episodic gait disturbance common in patients with Parkinson's disease. Recent evidences suggest a complex interplay between gait impairment and executive functions. Aim of our study was to evaluate whether specific motor conditions (sitting or walking) influence cognitive performance in patients with or without different types of <span class="hlt">freezing</span>. Eight healthy controls, eight patients without <span class="hlt">freezing</span>, nine patients with levodopa-responsive and nine patients with levodopa-resistant <span class="hlt">freezing</span> received a clinical and neuropsychological assessment during two randomly performed conditions: at rest and during walking. At rest, patients with levodopa-resistant <span class="hlt">freezing</span> performed worse than patients without <span class="hlt">freezing</span> on tests of phonological fluency (p = 0.01). No differences among the four groups were detected during walking. When cognitive performances during walking were compared to the performance at rest, there was a significant decline of verbal episodic memory task (Rey Auditory Verbal Learning Test) in patients without <span class="hlt">freezing</span> and with levodopa-responsive <span class="hlt">freezing</span>. Interestingly, walking improved performance on the phonological fluency task in patients with levodopa-resistant <span class="hlt">freezing</span> (p = 0.04). Compared to patients without <span class="hlt">freezing</span>, patients with levodopa-resistant <span class="hlt">freezing</span> perform worse when tested while seated in tasks of phonological verbal fluency. Surprisingly, gait was associated with a paradoxical improvement of phonological verbal fluency in the patients with levodopa-resistant <span class="hlt">freezing</span> whilst walking determined a worsening of episodic memory in the other patient groups. Copyright © 2014 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100011222','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100011222"><span><span class="hlt">Freeze</span> Tape Casting of Functionally Graded Porous Ceramics</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sofie, Stephen W.</p> <p>2007-01-01</p> <p><span class="hlt">Freeze</span> tape casting is a means of making preforms of ceramic sheets that, upon subsequent completion of fabrication processing, can have anisotropic and/or functionally graded properties that notably include aligned and graded porosity. <span class="hlt">Freeze</span> tape casting was developed to enable optimization of the microstructures of porous ceramic components for use as solid oxide electrodes in fuel cells: Through alignment and grading of pores, one can tailor surface areas and diffusion channels for flows of gas and liquid species involved in fuel-cell reactions. <span class="hlt">Freeze</span> tape casting offers similar benefits for fabrication of optimally porous ceramics for use as catalysts, gas sensors, and filters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22105981-use-freeze-casting-advanced-burner-reactor-fuel-design','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22105981-use-freeze-casting-advanced-burner-reactor-fuel-design"><span>Use of <span class="hlt">freeze</span>-casting in advanced burner reactor fuel design</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Lang, A. L.; Yablinsky, C. A.; Allen, T. R.</p> <p>2012-07-01</p> <p>This paper will detail the modeling of a fast reactor with fuel pins created using a <span class="hlt">freeze</span>-casting process. <span class="hlt">Freeze</span>-casting is a method of creating an inert scaffold within a fuel pin. The scaffold is created using a directional solidification process and results in open porosity for emplacement of fuel, with pores ranging in size from 300 microns to 500 microns in diameter. These pores allow multiple fuel types and enrichments to be loaded into one fuel pin. Also, each pore could be filled with varying amounts of fuel to allow for the specific volume of fission gases created by thatmore » fuel type. Currently fast reactors, including advanced burner reactors (ABR's), are not economically feasible due to the high cost of operating the reactors and of reprocessing the fuel. However, if the fuel could be very precisely placed, such as within a <span class="hlt">freeze</span>-cast scaffold, this could increase fuel performance and result in a valid design with a much lower cost per megawatt. In addition to competitive costs, <span class="hlt">freeze</span>-cast fuel would also allow for selective breeding or burning of actinides within specific locations in fast reactors. For example, fast flux peak locations could be utilized on a minute scale to target specific actinides for transmutation. <span class="hlt">Freeze</span>-cast fuel is extremely flexible and has great potential in a variety of applications. This paper performs initial modeling of <span class="hlt">freeze</span>-cast fuel, with the generic fast reactor parameters for this model based on EBR-II. The core has an assumed power of 62.5 MWt. The neutronics code used was Monte Carlo N-Particle (MCNP5) transport code. Uniform pore sizes were used in increments of 100 microns. Two different <span class="hlt">freeze</span>-cast scaffold materials were used: ceramic (MgO-ZrO{sub 2}) and steel (SS316L). Separate models were needed for each material because the <span class="hlt">freeze</span>-cast ceramic and metal scaffolds have different structural characteristics and overall porosities. Basic criticality results were compiled for the various models</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24362564','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24362564"><span>Three keys to the radiation of angiosperms into <span class="hlt">freezing</span> environments.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zanne, Amy E; Tank, David C; Cornwell, William K; Eastman, Jonathan M; Smith, Stephen A; FitzJohn, Richard G; McGlinn, Daniel J; O'Meara, Brian C; Moles, Angela T; Reich, Peter B; Royer, Dana L; Soltis, Douglas E; Stevens, Peter F; Westoby, Mark; Wright, Ian J; Aarssen, Lonnie; Bertin, Robert I; Calaminus, Andre; Govaerts, Rafaël; Hemmings, Frank; Leishman, Michelle R; Oleksyn, Jacek; Soltis, Pamela S; Swenson, Nathan G; Warman, Laura; Beaulieu, Jeremy M</p> <p>2014-02-06</p> <p>Early flowering plants are thought to have been woody species restricted to warm habitats. This lineage has since radiated into almost every climate, with manifold growth forms. As angiosperms spread and climate changed, they evolved mechanisms to cope with episodic <span class="hlt">freezing</span>. To explore the evolution of traits underpinning the ability to persist in <span class="hlt">freezing</span> conditions, we assembled a large species-level database of growth habit (woody or herbaceous; 49,064 species), as well as leaf phenology (evergreen or deciduous), diameter of hydraulic conduits (that is, xylem vessels and tracheids) and climate occupancies (exposure to <span class="hlt">freezing</span>). To model the evolution of species' traits and climate occupancies, we combined these data with an unparalleled dated molecular phylogeny (32,223 species) for land plants. Here we show that woody clades successfully moved into <span class="hlt">freezing</span>-prone environments by either possessing transport networks of small safe conduits and/or shutting down hydraulic function by dropping leaves during <span class="hlt">freezing</span>. Herbaceous species largely avoided <span class="hlt">freezing</span> periods by senescing cheaply constructed aboveground tissue. Growth habit has long been considered labile, but we find that growth habit was less labile than climate occupancy. Additionally, <span class="hlt">freezing</span> environments were largely filled by lineages that had already become herbs or, when remaining woody, already had small conduits (that is, the trait evolved before the climate occupancy). By contrast, most deciduous woody lineages had an evolutionary shift to seasonally shedding their leaves only after exposure to <span class="hlt">freezing</span> (that is, the climate occupancy evolved before the trait). For angiosperms to inhabit novel cold environments they had to gain new structural and functional trait solutions; our results suggest that many of these solutions were probably acquired before their foray into the cold.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010064081&hterms=hydrate&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dhydrate','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010064081&hterms=hydrate&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dhydrate"><span>Stratospheric Polar <span class="hlt">Freezing</span> Belt Causes Denitrification</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Tabazadeh, A.; Jensen, E. J.; Toon, O. B.; Drdla, K.; Schoeberl, M. R.; Gore, Warren J. (Technical Monitor)</p> <p>2001-01-01</p> <p>Trajectory cloud model calculations are presented to show that homogeneous <span class="hlt">freezing</span> of nitric acid hydrates can produce a polar <span class="hlt">freezing</span> belt in both hemispheres that can cause denitrification. While hydrate cloud microphysical properties are similar over both poles, the shorter persistence of clouds in the Arctic prevents the depth of the denitrified layers from growing beyond a few kilometers. The 1999-2000 Arctic winter is unique in showing a distinct denitrification profile with a depth of approx. 4.5 km that is nearly half as deep as that computed for a typical Antarctic winter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26981867','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26981867"><span>Demonstrating Functional Equivalence of Pilot and Production Scale <span class="hlt">Freeze</span>-Drying of BCG.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ten Have, R; Reubsaet, K; van Herpen, P; Kersten, G; Amorij, J-P</p> <p>2016-01-01</p> <p>Process analytical technology (PAT)-tools were used to monitor <span class="hlt">freeze</span>-drying of Bacille Calmette-Guérin (BCG) at pilot and production scale. Among the evaluated PAT-tools, there is the novel use of the vacuum valve open/close frequency for determining the endpoint of primary drying at production scale. The duration of primary drying, the BCG survival rate, and the residual moisture content (RMC) were evaluated using two different <span class="hlt">freeze</span>-drying protocols and were found to be independent of the <span class="hlt">freeze</span>-dryer scale evidencing functional equivalence. The absence of an effect of the <span class="hlt">freeze</span>-dryer scale on the process underlines the feasibility of the pilot scale <span class="hlt">freeze</span>-dryer for further BCG <span class="hlt">freeze</span>-drying process optimization which may be carried out using a medium without BCG.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhCS.870a2018C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhCS.870a2018C"><span>Experimental research on durability of recycled aggregate concrete under <span class="hlt">freeze</span>- thaw cycles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cheng, Yanqiu; Shang, Xiaoyu; Zhang, Youjia</p> <p>2017-07-01</p> <p>The <span class="hlt">freeze</span>-thaw durability of recycled aggregate concrete has significance for the concrete buildings in the cold region. In this paper, the rapid <span class="hlt">freezing</span> and thawing cycles experience on recycle aggregate concrete was conducted to study on the effects of recycle aggregate amount, water-binder ratio and fly ash on <span class="hlt">freeze</span>-thaw durability of recycle aggregate concrete. The results indicates that recycle aggregate amount makes the significant influence on the <span class="hlt">freeze</span>-thaw durability. With the increase of recycled aggregates amount, the <span class="hlt">freeze</span>-thaw resistance for recycled aggregate concrete decreases. Recycled aggregate concrete with lower water cement ratio demonstrates better performance of <span class="hlt">freeze</span>-thaw durability. It is advised that the amount of fly ash is less than 30% for admixture of recycled aggregates in the cold region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26853683','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26853683"><span>Recent developments in novel <span class="hlt">freezing</span> and thawing technologies applied to foods.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wu, Xiao-Fei; Zhang, Min; Adhikari, Benu; Sun, Jincai</p> <p>2017-11-22</p> <p>This article reviews the recent developments in novel <span class="hlt">freezing</span> and thawing technologies applied to foods. These novel technologies improve the quality of frozen and thawed foods and are energy efficient. The novel technologies applied to <span class="hlt">freezing</span> include pulsed electric field pre-treatment, ultra-low temperature, ultra-rapid <span class="hlt">freezing</span>, ultra-high pressure and ultrasound. The novel technologies applied to thawing include ultra-high pressure, ultrasound, high voltage electrostatic field (HVEF), and radio frequency. Ultra-low temperature and ultra-rapid <span class="hlt">freezing</span> promote the formation and uniform distribution of small ice crystals throughout frozen foods. Ultra-high pressure and ultrasound assisted <span class="hlt">freezing</span> are non-thermal methods and shorten the <span class="hlt">freezing</span> time and improve product quality. Ultra-high pressure and HVEF thawing generate high heat transfer rates and accelerate the thawing process. Ultrasound and radio frequency thawing can facilitate thawing process by volumetrically generating heat within frozen foods. It is anticipated that these novel technologies will be increasingly used in food industries in the future.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.5033D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.5033D"><span>New particle dependant parameterizations of heterogeneous <span class="hlt">freezing</span> processes.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Diehl, Karoline; Mitra, Subir K.</p> <p>2014-05-01</p> <p>For detailed investigations of cloud microphysical processes an adiabatic air parcel model with entrainment is used. It represents a spectral bin model which explicitly solves the microphysical equations. The initiation of the ice phase is parameterized and describes the effects of different types of ice nuclei (mineral dust, soot, biological particles) in immersion, contact, and deposition modes. As part of the research group INUIT (Ice Nuclei research UnIT), existing parameterizations have been modified for the present studies and new parameterizations have been developed mainly on the basis of the outcome of INUIT experiments. Deposition <span class="hlt">freezing</span> in the model is dependant on the presence of dry particles and on ice supersaturation. The description of contact <span class="hlt">freezing</span> combines the collision kernel of dry particles with the fraction of frozen drops as function of temperature and particle size. A new parameterization of immersion <span class="hlt">freezing</span> has been coupled to the mass of insoluble particles contained in the drops using measured numbers of ice active sites per unit mass. Sensitivity studies have been performed with a convective temperature and dew point profile and with two dry aerosol particle number size distributions. Single and coupled <span class="hlt">freezing</span> processes are studied with different types of ice nuclei (e.g., bacteria, illite, kaolinite, feldspar). The strength of convection is varied so that the simulated cloud reaches different levels of temperature. As a parameter to evaluate the results the ice water fraction is selected which is defined as the relation of the ice water content to the total water content. Ice water fractions between 0.1 and 0.9 represent mixed-phase clouds, larger than 0.9 ice clouds. The results indicate the sensitive parameters for the formation of mixed-phase and ice clouds are: 1. broad particle number size distribution with high number of small particles, 2. temperatures below -25°C, 3. specific mineral dust particles as ice nuclei such</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22417560','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22417560"><span>Effect of <span class="hlt">freezing</span> temperature on the color of frozen salmon.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ottestad, Silje; Enersen, Grethe; Wold, Jens Petter</p> <p>2011-09-01</p> <p>New <span class="hlt">freezing</span> methods developed with the purpose of improved product quality after thawing can sometimes be difficult to get accepted in the market. The reason for this is the formation of ice crystals that can give the product a temporary color loss and make it less appealing. We have here used microscopy to study ice crystal size as a function of <span class="hlt">freezing</span> temperature by investigating the voids in the cell tissue left by the ice crystals. We have also investigated how <span class="hlt">freezing</span> temperature affects the color and the visible absorption spectra of frozen salmon. <span class="hlt">Freezing</span> temperatures previously determined to be the best for quality after thawing (-40 to -60 °C) were found to cause a substantial loss in perceived color intensity during frozen state. This illustrated the conflict between optimal <span class="hlt">freezing</span> temperatures with respect to quality after thawing against visual appearance during frozen state. Low <span class="hlt">freezing</span> temperatures gave many small ice crystals, increased light scattering and an increased absorption level for all wavelengths in the visible region. Increased astaxanthin concentration on the other hand would give higher absorption at 490 nm. The results showed a clear potential of using visible interactance spectroscopy to differentiate between poor product coloration due to lack of pigmentation and temporary color loss due to light scattering by ice crystal. This type of measurements could be a useful tool in the development of new <span class="hlt">freezing</span> methods and to monitor ice crystal growth during frozen storage. It could also potentially be used by the industry to prove good product quality. In this article we have shown that <span class="hlt">freezing</span> food products at intermediate to low temperatures (-40 to -80 °C) can result in paler color during frozen state, which could affect consumer acceptance. We have also presented a spectroscopic method that can separate between poor product color and temporary color loss due to <span class="hlt">freezing</span>. © 2011 Institute of Food Technologists®</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017E3SWC..2200072J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E3SWC..2200072J"><span>Indirect contact <span class="hlt">freeze</span> water desalination for an ice maker machine - CFD simulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jayakody, Harith; Al-Dadah, Raya; Mahmoud, Saad</p> <p>2017-11-01</p> <p>To offer for potable water shortages, sea water desalination is a potential solution for the global rising demand for fresh water. The latent heat of fusion is about one-seventh the latent heat of vaporisation, thus indicating the benefit of lower energy consumption for the <span class="hlt">freeze</span> desalination process. Limited literature is reported on computational fluid dynamics (CFD) on <span class="hlt">freeze</span> desalination. Therefore, analysing and investigating thermodynamic processes are easily conducted by the powerful tool of CFD. A single unit of ice formation in an ice maker machine was modelled using ANSYS Fluent software three-dimensionally. Energy, species transport and solidification/melting modules were used in building the CFD model. Parametric analysis was conducted using the established CFD model to predict the effects of <span class="hlt">freezing</span> temperature and the geometry of the ice maker machine; on ice production and the <span class="hlt">freezing</span> time. Lower <span class="hlt">freezing</span> temperatures allowed more ice production and faster <span class="hlt">freezing</span>. Increasing the diameter and the length of the <span class="hlt">freezing</span> tube enabled more ice to be produced.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/5588809-fuel-freeze-point-investigations-final-report-september-march','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5588809-fuel-freeze-point-investigations-final-report-september-march"><span>Fuel <span class="hlt">freeze</span>-point investigations. Final report, September 1982-March 1984</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Desmarais, L.A.; Tolle, F.F.</p> <p>1984-07-01</p> <p>The objective of this program was to conduct a detailed assessment of the low-temperature environment to which USAF aircraft are exposed for the purpose of defining a maximum acceptable fuel <span class="hlt">freeze</span>-point and also to define any operational changes required with the use of a high <span class="hlt">freeze</span>-point fuel. A previous study of B-52, C-141, and KC-135 operational missions indicated that the -58 C <span class="hlt">freeze</span> point specification was too conservative. Based on recommendations resulting from the previous program, several improvements in the method of analysis were made, such as: expansion of the atmospheric temperature data base, the addition of ground temperature analysis,more » the addition of fuel-<span class="hlt">freezing</span> analysis to the one-dimensional fuel-temperature computer program, and the examination of heat transfer in external fuel tanks, such as pylon or tip tanks. The B-52, C-141, and KC-135 mission were analyzed again, along with the operational missions of two tactical airplanes, the A-10 and F-15; -50C was determined to be the maximum allowable <span class="hlt">freeze</span> point for a general-purpose USAF aviation turbine fuel. Higher <span class="hlt">freeze</span> points can be tolerated if the probability of operational interference is acceptably low or if operational changes can be made. Study of atmospheric temperatures encountered for the missions of the five-study aircraft indicates that a maximum <span class="hlt">freeze</span> point of -48 C would not likely create any operational difficulties in Northern Europe.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21302371','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21302371"><span>Protein and solute distribution in drug substance containers during frozen storage and post-thawing: a tool to understand and define <span class="hlt">freezing</span>-thawing parameters in biotechnology process development.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kolhe, Parag; Badkar, Advait</p> <p>2011-01-01</p> <p>Active pharmaceutical ingredient for biotechnology-based drugs, commonly known as drug substance (DS), is often stored frozen for longer shelf-life. <span class="hlt">Freezing</span> DS enhances stability by slowing down reaction rates that lead to protein instability, minimizes the risk of microbial growth, and eliminates the risk of transport-related stress. High density polyethylene bottles are commonly used for storing monoclonal antibody DS due to good mechanical stress/strain resistant properties even at low temperatures. Despite the aforementioned advantages for frozen storage of DS, this is not devoid of risks. Proteins are known to undergo ice-water surface denaturation, cryoconcentration, and cold denaturation during <span class="hlt">freezing</span>. A systematic investigation was performed to better understand the protein and solute distribution along with potential of aggregate formation during <span class="hlt">freeze</span> and thaw process. A significant solute and protein concentration <span class="hlt">gradient</span> was observed for both frozen and thawed DS bottles. In case of thawed DS, cryoconcentration was localized in the bottom layer and a linear increase in concentration as a function of liquid depth was observed. On the other hand, for frozen DS, a "bell shaped" cryoconcentration distribution was observed between the bottom layers and centre position. A cryoconcentration of almost three-fold was observed for frozen DS in the most concentrated part when <span class="hlt">freezing</span> was conducted at -20 and -40 °C and 2.5-fold cryoconcentration was observed in the thawed DS before mixing. The information obtained in this study is critical to design <span class="hlt">freeze</span> thaw experiments, storage condition determination, and process improvement in manufacturing environment. Copyright © 2011 American Institute of Chemical Engineers (AIChE).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4175083','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4175083"><span>Does Anxiety Cause <span class="hlt">Freezing</span> of Gait in Parkinson's Disease?</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ehgoetz Martens, Kaylena A.; Ellard, Colin G.; Almeida, Quincy J.</p> <p>2014-01-01</p> <p>Individuals with Parkinson's disease (PD) commonly experience <span class="hlt">freezing</span> of gait under time constraints, in narrow spaces, and in the dark. One commonality between these different situations is that they may all provoke anxiety, yet anxiety has never been directly examined as a cause of FOG. In this study, virtual reality was used to induce anxiety and evaluate whether it directly causes FOG. Fourteen patients with PD and <span class="hlt">freezing</span> of gait (Freezers) and 17 PD without <span class="hlt">freezing</span> of gait (Non-Freezers) were instructed to walk in two virtual environments: (i) across a plank that was located on the ground (LOW), (ii) across a plank above a deep pit (HIGH). Multiple synchronized motion capture cameras updated participants' movement through the virtual environment in real-time, while their gait was recorded. Anxiety levels were evaluated after each trial using self-assessment manikins. Freezers performed the experiment on two separate occasions (in their ON and OFF state). Freezers reported higher levels of anxiety compared to Non-Freezers (p<0.001) and all patients reported greater levels of anxiety when walking across the HIGH plank compared to the LOW (p<0.001). Freezers experienced significantly more <span class="hlt">freezing</span> of gait episodes (p = 0.013) and spent a significantly greater percentage of each trial frozen (p = 0.005) when crossing the HIGH plank. This finding was even more pronounced when comparing Freezers in their OFF state. Freezers also had greater step length variability in the HIGH compared to the LOW condition, while the step length variability in Non-Freezers did not change. In conclusion, this was the first study to directly compare <span class="hlt">freezing</span> of gait in anxious and non-anxious situations. These results present strong evidence that anxiety is an important mechanism underlying <span class="hlt">freezing</span> of gait and supports the notion that the limbic system may have a profound contribution to <span class="hlt">freezing</span> in PD. PMID:25250691</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25250691','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25250691"><span>Does anxiety cause <span class="hlt">freezing</span> of gait in Parkinson's disease?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ehgoetz Martens, Kaylena A; Ellard, Colin G; Almeida, Quincy J</p> <p>2014-01-01</p> <p>Individuals with Parkinson's disease (PD) commonly experience <span class="hlt">freezing</span> of gait under time constraints, in narrow spaces, and in the dark. One commonality between these different situations is that they may all provoke anxiety, yet anxiety has never been directly examined as a cause of FOG. In this study, virtual reality was used to induce anxiety and evaluate whether it directly causes FOG. Fourteen patients with PD and <span class="hlt">freezing</span> of gait (Freezers) and 17 PD without <span class="hlt">freezing</span> of gait (Non-Freezers) were instructed to walk in two virtual environments: (i) across a plank that was located on the ground (LOW), (ii) across a plank above a deep pit (HIGH). Multiple synchronized motion capture cameras updated participants' movement through the virtual environment in real-time, while their gait was recorded. Anxiety levels were evaluated after each trial using self-assessment manikins. Freezers performed the experiment on two separate occasions (in their ON and OFF state). Freezers reported higher levels of anxiety compared to Non-Freezers (p < 0.001) and all patients reported greater levels of anxiety when walking across the HIGH plank compared to the LOW (p < 0.001). Freezers experienced significantly more <span class="hlt">freezing</span> of gait episodes (p = 0.013) and spent a significantly greater percentage of each trial frozen (p = 0.005) when crossing the HIGH plank. This finding was even more pronounced when comparing Freezers in their OFF state. Freezers also had greater step length variability in the HIGH compared to the LOW condition, while the step length variability in Non-Freezers did not change. In conclusion, this was the first study to directly compare <span class="hlt">freezing</span> of gait in anxious and non-anxious situations. These results present strong evidence that anxiety is an important mechanism underlying <span class="hlt">freezing</span> of gait and supports the notion that the limbic system may have a profound contribution to <span class="hlt">freezing</span> in PD.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080008236','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080008236"><span>Device and method for determining <span class="hlt">freezing</span> points</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mathiprakasam, Balakrishnan (Inventor)</p> <p>1986-01-01</p> <p>A <span class="hlt">freezing</span> point method and device (10) are disclosed. The method and device pertain to an inflection point technique for determining the <span class="hlt">freezing</span> points of mixtures. In both the method and device (10), the mixture is cooled to a point below its anticipated <span class="hlt">freezing</span> point and then warmed at a substantially linear rate. During the warming process, the rate of increase of temperature of the mixture is monitored by, for example, thermocouple (28) with the thermocouple output signal being amplified and differentiated by a differentiator (42). The rate of increase of temperature data are analyzed and a peak rate of increase of temperature is identified. In the preferred device (10) a computer (22) is utilized to analyze the rate of increase of temperature data following the warming process. Once the maximum rate of increase of temperature is identified, the corresponding temperature of the mixture is located and earmarked as being substantially equal to the <span class="hlt">freezing</span> point of the mixture. In a preferred device (10), the computer (22), in addition to collecting the temperature and rate of change of temperature data, controls a programmable power supply (14) to provide a predetermined amount of cooling and warming current to thermoelectric modules (56).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25403324','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25403324"><span>Intact preservation of environmental samples by <span class="hlt">freezing</span> under an alternating magnetic field.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Morono, Yuki; Terada, Takeshi; Yamamoto, Yuhji; Xiao, Nan; Hirose, Takehiro; Sugeno, Masaya; Ohwada, Norio; Inagaki, Fumio</p> <p>2015-04-01</p> <p>The study of environmental samples requires a preservation system that stabilizes the sample structure, including cells and biomolecules. To address this fundamental issue, we tested the cell alive system (CAS)-<span class="hlt">freezing</span> technique for subseafloor sediment core samples. In the CAS-<span class="hlt">freezing</span> technique, an alternating magnetic field is applied during the <span class="hlt">freezing</span> process to produce vibration of water molecules and achieve a stable, super-cooled liquid phase. Upon further cooling, the temperature decreases further, achieving a uniform <span class="hlt">freezing</span> of sample with minimal ice crystal formation. In this study, samples were preserved using the CAS and conventional <span class="hlt">freezing</span> techniques at 4, -20, -80 and -196 (liquid nitrogen) °C. After 6 months of storage, microbial cell counts by conventional <span class="hlt">freezing</span> significantly decreased (down to 10.7% of initial), whereas that by CAS-<span class="hlt">freezing</span> resulted in minimal. When Escherichia coli cells were tested under the same <span class="hlt">freezing</span> conditions and storage for 2.5 months, CAS-frozen E. coli cells showed higher viability than the other conditions. In addition, an alternating magnetic field does not impact on the direction of remanent magnetization in sediment core samples, although slight partial demagnetization in intensity due to <span class="hlt">freezing</span> was observed. Consequently, our data indicate that the CAS technique is highly useful for the preservation of environmental samples. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23812315','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23812315"><span>Heat transfer coefficient of cryotop during <span class="hlt">freezing</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, W J; Zhou, X L; Wang, H S; Liu, B L; Dai, J J</p> <p>2013-01-01</p> <p>Cryotop is an efficient vitrification method for cryopreservation of oocytes. It has been widely used owing to its simple operation and high <span class="hlt">freezing</span> rate. Recently, the heat transfer performance of cryotop was studied by numerical simulation in several studies. However, the range of heat transfer coefficient in the simulation is uncertain. In this study, the heat transfer coefficient for cryotop during <span class="hlt">freezing</span> process was analyzed. The cooling rates of 40 percent ethylene glycol (EG) droplet in cryotop during <span class="hlt">freezing</span> were measured by ultra-fast measurement system and calculated by numerical simulation at different value of heat transfer coefficient. Compared with the results obtained by two methods, the range of the heat transfer coefficient necessary for the numerical simulation of cryotop was determined, which is between 9000 W/(m(2)·K) and 10000 W/(m (2)·K).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27232200','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27232200"><span>Image reconstruction from few-view CT data by <span class="hlt">gradient</span>-domain dictionary learning.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hu, Zhanli; Liu, Qiegen; Zhang, Na; Zhang, Yunwan; Peng, Xi; Wu, Peter Z; Zheng, Hairong; Liang, Dong</p> <p>2016-05-21</p> <p>Decreasing the number of projections is an effective way to reduce the radiation dose exposed to patients in medical computed tomography (CT) imaging. However, incomplete projection data for CT reconstruction will result in artifacts and distortions. In this paper, a novel dictionary learning algorithm operating in the <span class="hlt">gradient</span>-domain (Grad-DL) is proposed for few-view CT reconstruction. Specifically, the dictionaries are trained from the horizontal and <span class="hlt">vertical</span> <span class="hlt">gradient</span> images, respectively and the desired image is reconstructed subsequently from the sparse representations of both <span class="hlt">gradients</span> by solving the least-square method. Since the <span class="hlt">gradient</span> images are sparser than the image itself, the proposed approach could lead to sparser representations than conventional DL methods in the image-domain, and thus a better reconstruction quality is achieved. To evaluate the proposed Grad-DL algorithm, both qualitative and quantitative studies were employed through computer simulations as well as real data experiments on fan-beam and cone-beam geometry. The results show that the proposed algorithm can yield better images than the existing algorithms.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AdSpR..39.1292N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AdSpR..39.1292N"><span>Use of total electron content data to analyze ionosphere electron density <span class="hlt">gradients</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nava, B.; Radicella, S. M.; Leitinger, R.; Coïsson, P.</p> <p></p> <p>In the presence of electron density <span class="hlt">gradients</span> the thin shell approximation for the ionosphere, used together with a simple mapping function to convert slant total electron content (TEC) to <span class="hlt">vertical</span> TEC, could lead to TEC conversion errors. These "mapping function errors" can therefore be used to detect the electron density <span class="hlt">gradients</span> in the ionosphere. In the present work GPS derived slant TEC data have been used to investigate the effects of the electron density <span class="hlt">gradients</span> in the middle and low latitude ionosphere under geomagnetic quiet and disturbed conditions. In particular the data corresponding to the geographic area of the American Sector for the days 5-7 April 2000 have been used to perform a complete analysis of mapping function errors based on the "coinciding pierce point technique". The results clearly illustrate the electron density <span class="hlt">gradient</span> effects according to the locations considered and to the actual levels of disturbance of the ionosphere. In addition, the possibility to assess an ionospheric shell height able to minimize the mapping function errors has been verified.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20050000227&hterms=bacterias&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dbacterias','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20050000227&hterms=bacterias&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dbacterias"><span>The development of concentration <span class="hlt">gradients</span> in a suspension of chemotactic bacteria</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hillesdon, A. J.; Pedley, T. J.; Kessler, J. O.</p> <p>1995-01-01</p> <p>When a suspension of bacterial cells of the species Bacillus subtilis is placed in a chamber with its upper surface open to the atmosphere complex bioconvection patterns are observed. These arise because the cells: (1) are denser than water; and (2) usually swim upwards, so that the density of an initially uniform suspension becomes greater at the top than the bottom. When the <span class="hlt">vertical</span> density <span class="hlt">gradient</span> becomes large enough, an overturning instability occurs which ultimately evolves into the observed patterns. The reason that the cells swim upwards is that they are aerotactic, i.e., they swim up <span class="hlt">gradients</span> of oxygen, and they consume oxygen. These properties are incorporated in conservation equations for the cell (N) and oxygen (C) concentrations, and these are solved in the pre-instability phase of development when N and C depend only on the <span class="hlt">vertical</span> coordinate and time. Numerical results are obtained for both shallow- and deep-layer chambers, which are intrinsically different and require different mathematical and numerical treatments. It is found that, for both shallow and deep chambers, a thin boundary layer, densely packed with cells, forms near the surface. Beneath this layer the suspension becomes severely depleted of cells. Furthermore, in the deep chamber cases, a discontinuity in the cell concentration arises between this cell-depleted region and a cell-rich region further below, where no significant oxygen concentration <span class="hlt">gradients</span> develop before the oxygen is fully consumed. The results obtained from the model are in good qualitative agreement with the experimental observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..44.3073S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..44.3073S"><span><span class="hlt">Vertical</span> structure of tropospheric winds on gas giants</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scott, R. K.; Dunkerton, T. J.</p> <p>2017-04-01</p> <p>Zonal mean zonal velocity profiles from cloud-tracking observations on Jupiter and Saturn are used to infer latitudinal variations of potential temperature consistent with a shear stable potential vorticity distribution. Immediately below the cloud tops, density stratification is weaker on the poleward and stronger on the equatorward flanks of midlatitude jets, while at greater depth the opposite relation holds. Thermal wind balance then yields the associated <span class="hlt">vertical</span> shears of midlatitude jets in an altitude range bounded above by the cloud tops and bounded below by the level where the latitudinal <span class="hlt">gradient</span> of static stability changes sign. The inferred <span class="hlt">vertical</span> shear below the cloud tops is consistent with existing thermal profiling of the upper troposphere. The sense of the associated mean meridional circulation in the upper troposphere is discussed, and expected magnitudes are given based on existing estimates of the radiative timescale on each planet.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25247927','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25247927"><span>'Banking time': egg <span class="hlt">freezing</span> and the negotiation of future fertility.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Waldby, Catherine</p> <p>2015-01-01</p> <p>This paper examines the relatively recent practice of non-medical egg <span class="hlt">freezing</span>, in which women bank their eggs for later use in conceiving a child. Non-medical egg <span class="hlt">freezing</span> has only been available for about the last five years, as new vitrification techniques have made the success rates for actual conception more reliable than the earlier method of slow <span class="hlt">freezing</span>. I draw on interviews with both clinicians and women who have banked their eggs to consider how this novel practice articulates with broader issues about the relationship between sexuality, reproduction and the political economy of household formation. Non-medical egg-<span class="hlt">freezing</span> provides a technical solution to a number of different problems women face with regard to the elongation of the life course, the extension of education, the cost of household establishment and the iterative nature of relationship formation, thematised by the ubiquity of internet dating among the interviewees. I focus on the ways women used egg <span class="hlt">freezing</span> to manage and reconcile different forms of time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27515084','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27515084"><span>Immunoelectron Microscopy of Cryofixed and <span class="hlt">Freeze</span>-Substituted Plant Tissues.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Takeuchi, Miyuki; Takabe, Keiji; Mineyuki, Yoshinobu</p> <p>2016-01-01</p> <p>Cryofixation and <span class="hlt">freeze</span>-substitution techniques provide excellent preservation of plant ultrastructure. The advantage of cryofixation is not only in structural preservation, as seen in the smooth plasma membrane, but also in the speed in arresting cell activity. Immunoelectron microscopy reveals the subcellular localization of molecules within cells. Immunolabeling in combination with cryofixation and <span class="hlt">freeze</span>-substitution techniques provides more detailed information on the immunoelectron-microscopic localization of molecules in the plant cell than can be obtained from chemically fixed tissues. Here, we introduce methods for immunoelectron microscopy of cryofixed and <span class="hlt">freeze</span>-substituted plant tissues.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C41D0757S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C41D0757S"><span>Snowmelt and Surface <span class="hlt">Freeze</span>/Thaw Timings over Alaska derived from Passive Microwave Observations using a Wavelet Classifier</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Steiner, N.; McDonald, K. C.; Dinardo, S. J.; Miller, C. E.</p> <p>2015-12-01</p> <p>Arctic permafrost soils contain a vast amount of organic carbon that will be released into the atmosphere as carbon dioxide or methane when thawed. Surface to air greenhouse gas fluxes are largely dependent on such surface controls as the frozen/thawed state of the snow and soil. Satellite remote sensing is an important means to create continuous mapping of surface properties. Advances in the ability to determine soil and snow <span class="hlt">freeze</span>/thaw timings from microwave frequency observations improves upon our ability to predict the response of carbon gas emission to warming through synthesis with in-situ observation, such as the 2012-2015 Carbon in Arctic Reservoir Vulnerability Experiment (CARVE). Surface <span class="hlt">freeze</span>/thaw or snowmelt timings are often derived using a constant or spatially/temporally variable threshold applied to time-series observations. Alternately, time-series singularity classifiers aim to detect discontinuous changes, or "edges", in time-series data similar to those that occur from the large contrast in dielectric constant during the <span class="hlt">freezing</span> or thaw of soil or snow. We use multi-scale analysis of continuous wavelet transform spectral <span class="hlt">gradient</span> brightness temperatures from various channel combinations of passive microwave radiometers, Advanced Microwave Scanning Radiometer (AMSR-E, AMSR2) and Special Sensor Microwave Imager (SSM/I F17) gridded at a 10 km posting with resolution proportional to the observational footprint. Channel combinations presented here aim to illustrate and differentiate timings of "edges" from transitions in surface water related to various landscape components (e.g. snow-melt, soil-thaw). To support an understanding of the physical basis of observed "edges" we compare satellite measurements with simple radiative transfer microwave-emission modeling of the snow, soil and vegetation using in-situ observations from the SNOw TELemetry (SNOTEL) automated weather stations. Results of <span class="hlt">freeze</span>/thaw and snow-melt timings and trends are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://rosap.ntl.bts.gov/view/dot/26631','DOTNTL'); return false;" href="https://rosap.ntl.bts.gov/view/dot/26631"><span><span class="hlt">Freeze</span>-thaw performance testing of whole concrete railroad ties.</span></a></p> <p><a target="_blank" href="http://ntlsearch.bts.gov/tris/index.do">DOT National Transportation Integrated Search</a></p> <p></p> <p>2013-10-01</p> <p><span class="hlt">Freezing</span> and thawing durability tests of prestressed concrete ties are normally performed according to ASTM C666 specifications. Small specimens are cut from the shoulders of concrete ties and tested through 300 cycles of <span class="hlt">freezing</span> and thawing. Saw-cu...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011RScI...82f5102C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011RScI...82f5102C"><span>Disaggregating meteorites by automated <span class="hlt">freeze</span> thaw</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Charles, Christopher R. J.</p> <p>2011-06-01</p> <p>An automated <span class="hlt">freeze</span>-thaw (AFT) instrument for disaggregating meteorites is described. Meteorite samples are immersed in 18.2 MΩ water and hermetically sealed in a clean 30 ml Teflon vial. This vial and its contents are dipped between baths of liquid nitrogen and hot water over a number of cycles by a dual-stepper motor system controlled by LabView. Uniform and periodic intervals of <span class="hlt">freezing</span> and thawing induce multiple expansions and contractions, such that cracks propagate along natural flaws in the meteorite for a sufficient number of AFT cycles. For the CR2 chondrite NWA801, the boundaries between different phases (i.e., silicates, metal, matrix) became progressively weaker and allowed for an efficient recovery of 500 individual chondrules and chondrule fragments spanning 0.2-4.7 mm diameters after 243 AFT cycles over 103.3 h. Further FT experiments on a basalt analog showed that the time required for <span class="hlt">freezing</span> and thawing the same number of cycles can be reduced by a factor of ˜4.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4794149','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4794149"><span>Demonstrating Functional Equivalence of Pilot and Production Scale <span class="hlt">Freeze</span>-Drying of BCG</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>ten Have, R.; Reubsaet, K.; van Herpen, P.; Kersten, G.; Amorij, J.-P.</p> <p>2016-01-01</p> <p>Process analytical technology (PAT)-tools were used to monitor <span class="hlt">freeze</span>-drying of Bacille Calmette-Guérin (BCG) at pilot and production scale. Among the evaluated PAT-tools, there is the novel use of the vacuum valve open/close frequency for determining the endpoint of primary drying at production scale. The duration of primary drying, the BCG survival rate, and the residual moisture content (RMC) were evaluated using two different <span class="hlt">freeze</span>-drying protocols and were found to be independent of the <span class="hlt">freeze</span>-dryer scale evidencing functional equivalence. The absence of an effect of the <span class="hlt">freeze</span>-dryer scale on the process underlines the feasibility of the pilot scale <span class="hlt">freeze</span>-dryer for further BCG <span class="hlt">freeze</span>-drying process optimization which may be carried out using a medium without BCG. PMID:26981867</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3114782','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3114782"><span>Adaptive Traits Are Maintained on Steep Selective <span class="hlt">Gradients</span> despite Gene Flow and Hybridization in the Intertidal Zone</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Canovas, Fernando; Ferreira Costa, Joana; Serrão, Ester A.; Pearson, Gareth A.</p> <p>2011-01-01</p> <p>Gene flow among hybridizing species with incomplete reproductive barriers blurs species boundaries, while selection under heterogeneous local ecological conditions or along strong <span class="hlt">gradients</span> may counteract this tendency. Congeneric, externally-fertilizing fucoid brown algae occur as distinct morphotypes along intertidal exposure <span class="hlt">gradients</span> despite gene flow. Combining analyses of genetic and phenotypic traits, we investigate the potential for physiological resilience to emersion stressors to act as an isolating mechanism in the face of gene flow. Along <span class="hlt">vertical</span> exposure <span class="hlt">gradients</span> in the intertidal zone of Northern Portugal and Northwest France, the mid-low shore species Fucus vesiculosus, the upper shore species Fucus spiralis, and an intermediate distinctive morphotype of F. spiralis var. platycarpus were morphologically characterized. Two diagnostic microsatellite loci recovered 3 genetic clusters consistent with prior morphological assignment. Phylogenetic analysis based on single nucleotide polymorphisms in 14 protein coding regions unambiguously resolved 3 clades; sympatric F. vesiculosus, F. spiralis, and the allopatric (in southern Iberia) population of F. spiralis var. platycarpus. In contrast, the sympatric F. spiralis var. platycarpus (from Northern Portugal) was distributed across the 3 clades, strongly suggesting hybridization/introgression with both other entities. Common garden experiments showed that physiological resilience following exposure to desiccation/heat stress differed significantly between the 3 sympatric genetic taxa; consistent with their respective <span class="hlt">vertical</span> distribution on steep environmental clines in exposure time. Phylogenetic analyses indicate that F. spiralis var. platycarpus is a distinct entity in allopatry, but that extensive gene flow occurs with both higher and lower shore species in sympatry. Experimental results suggest that strong selection on physiological traits across steep intertidal exposure <span class="hlt">gradients</span> acts to maintain</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMGC23L1258G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMGC23L1258G"><span>Spatio-temporal variability of <span class="hlt">vertical</span> <span class="hlt">gradients</span> of major meteorological observations around the Tibetan Plateau</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guo, X.; Wang, L.; Tian, L.</p> <p>2015-12-01</p> <p>The near-surface air temperature lapse rate (TLR), wind speed <span class="hlt">gradient</span> (WSG), and precipitation <span class="hlt">gradient</span> (PG) provide crucial parameters used in models of mountain climate and hydrology. The complex mountain terrain and vast area of the Tibetan Plateau (TP) make such factors particularly important. With daily data from 161 meteorological stations over the past 43 years (1970-2012), we analyse the spatio-temporal variations of TLRs, WSGs, and PGs over and around TP, derived using linear regression methods and dividing the study area into zones based on spatial variations. Results of this study include: (1) The observed TLR varies from -0.46 to -0.73 ∘C (100 m) -1, with averaged TLRs of -0.60,-0.62, and -0.59 ∘C (100 m) -1 for Tmax, Tmin,and Tmean , respectively. The averaged TLR is slightly less than the global mean of -0.65 ∘C (100 m) -1 . The spatial variability of TLR relates to climate conditions, wherein the TLR increases in dry conditions and in cold months (October-April), while it lessens in humid regions and during warm months (May-September). (2) The estimated annual WSG ranges from 0.07 to 0.17m s -1 (100 m) -1. Monthly WSGs show a marked seasonal shift, in which higher WSGs can be explained by the high intensity of prevailing wind. (3) Positive summer PGs vary from 12.08 in the central TP to 26.14 mm (100 m) -1 in northeastern Qinghai and the southern TP, but a reverse <span class="hlt">gradient</span> prevails in Yunnan and parts of Sichuan Province. (4) The regional warming over TP is more evident in winter, and Tmin demonstrated the most prominent warming compared with Tmax and Tmean. Environments at high elevations experience more rapid changes in temperatures (Tmax, Tmin,and Tmean) than those at low elevations, which is especially true in winter and for Tmin. Furthermore, inter-annual variation of TLRs is linked to elevation-dependent warming.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..MARJ34006P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..MARJ34006P"><span>The Structural Properties and Stability of Monoclonal Antibodies at <span class="hlt">Freezing</span> Conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Perevozchikova, Tatiana; Zarraga, Isidro; Scherer, Thomas; Wagner, Norman; Liu, Yun</p> <p>2013-03-01</p> <p>Monoclonal Antibodies (MAb) have become a crucial therapeutic agent in a number of anti-cancer treatments. Due to the inherent unstable nature of proteins in an aqueous formulation, a <span class="hlt">freeze</span>-drying method has been developed to maintain long-term stability of biotherapeutics. The microstructural changes in Mabs during <span class="hlt">freezing</span>, however, remain not fully described, and it was proposed that the formed morphology of <span class="hlt">freeze</span> drying samples could affect the final product quality after reconstitution. Furthermore, it is well known that proteins tend to aggregate during the <span class="hlt">freezing</span> process if a careful processing procedure is not formulated. Small Angle Neutron Scattering (SANS) is a powerful tool to investigate the structural properties and interactions of Mabs during various stages of lyophilization in situ. Here we present the SANS results of <span class="hlt">freeze</span>-thaw studies on two MAbs at several different <span class="hlt">freezing</span> temperatures. While the chosen proteins share a significant sequence homology, their <span class="hlt">freezing</span> properties are found to be strikingly distinctive. We also show the effect of excipients, concentration and quenching speed on the final morphology of the frozen samples. These findings provide critical information for more effective lyophilization schemes for therapeutic proteins, as well as increase our understanding on structural properties of proteins under cryogenic conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4761790','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4761790"><span>Summer <span class="hlt">Freezing</span> Resistance: A Critical Filter for Plant Community Assemblies in Mediterranean High Mountains</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Pescador, David S.; Sierra-Almeida, Ángela; Torres, Pablo J.; Escudero, Adrián</p> <p>2016-01-01</p> <p>Assessing <span class="hlt">freezing</span> community response and whether <span class="hlt">freezing</span> resistance is related to other functional traits is essential for understanding alpine community assemblages, particularly in Mediterranean environments where plants are exposed to <span class="hlt">freezing</span> temperatures and summer droughts. Thus, we characterized the leaf <span class="hlt">freezing</span> resistance of 42 plant species in 38 plots at Sierra de Guadarrama (Spain) by measuring their ice nucleation temperature, <span class="hlt">freezing</span> point (FP), and low-temperature damage (LT50), as well as determining their <span class="hlt">freezing</span> resistance mechanisms (i.e., tolerance or avoidance). The community response to <span class="hlt">freezing</span> was estimated for each plot as community weighted means (CWMs) and functional diversity (FD), and we assessed their relative importance with altitude. We established the relationships between <span class="hlt">freezing</span> resistance, growth forms, and four key plant functional traits (i.e., plant height, specific leaf area, leaf dry matter content (LDMC), and seed mass). There was a wide range of <span class="hlt">freezing</span> resistance responses and more than in other alpine habitats. At the community level, the CWMs of FP and LT50 responded negatively to altitude, whereas the FD of both traits increased with altitude. The proportion of <span class="hlt">freezing</span>-tolerant species also increased with altitude. The ranges of FP and LT50 varied among growth forms, and only leaf dry matter content was negatively correlated with <span class="hlt">freezing</span>-resistance traits. Summer <span class="hlt">freezing</span> events represent important abiotic filters for assemblies of Mediterranean high mountain communities, as suggested by the CWMs. However, a concomitant summer drought constraint may also explain the high <span class="hlt">freezing</span> resistance of species that thrive in these areas and the lower FD of <span class="hlt">freezing</span> resistance traits at lower altitudes. Leaves with high dry matter contents may maintain turgor at lower water potential and enhance drought tolerance in parallel to <span class="hlt">freezing</span> resistance. This adaptation to drought seems to be a general prerequisite for plants</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28511048','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28511048"><span>Defensive <span class="hlt">freezing</span> links Hypothalamic-Pituitary-Adrenal-axis activity and internalizing symptoms in humans.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Niermann, Hannah C M; Figner, Bernd; Tyborowska, Anna; van Peer, Jacobien M; Cillessen, Antonius H N; Roelofs, Karin</p> <p>2017-08-01</p> <p>The Hypothalamic-Pituitary-Adrenal (HPA)-axis plays an important role in the expression of defensive <span class="hlt">freezing</span>. Adaptive <span class="hlt">freezing</span> reactivity, characterized by an immediate increase in acute stress and timely termination upon threat offset or need to act, is essential for adequate stress coping. Blunted HPA-axis activity in animals is associated with blunted <span class="hlt">freezing</span> reactivity and internalizing symptoms. Despite their potential relevance, it remains unknown whether these mechanisms apply to humans and human psychopathology. Using a well-established method combining electrocardiography and posturography, we assessed <span class="hlt">freezing</span> before, immediately after, and one hour after a stress induction in 92 human adolescents. In line with animal models, human adolescents showed stress-induced <span class="hlt">freezing</span>, as quantified by relative reductions in heart rate and body sway after, as compared to before, stress. Moreover, relatively lower basal cortisol was associated with reduced stress-induced <span class="hlt">freezing</span> reactivity (i.e., less immediate <span class="hlt">freezing</span> and less recovery). Path analyses showed that decreased <span class="hlt">freezing</span> recovery in individuals with reduced cortisol levels was associated with increased levels of internalizing symptoms. These findings suggest that reduced <span class="hlt">freezing</span> recovery may be a promising marker for the etiology of internalizing symptoms. Copyright © 2017 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26115177','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26115177"><span>Emerging techniques for assisting and accelerating food <span class="hlt">freezing</span> processes: A review of recent research progresses.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cheng, Lina; Sun, Da-Wen; Zhu, Zhiwei; Zhang, Zi</p> <p>2017-03-04</p> <p><span class="hlt">Freezing</span> plays an important role in food preservation and the emergence of rapid <span class="hlt">freezing</span> technologies can be highly beneficial to the food industry. This paper reviews some novel food <span class="hlt">freezing</span> technologies, including high-pressure <span class="hlt">freezing</span> (HPF), ultrasound-assisted <span class="hlt">freezing</span> (UAF), electrically disturbed <span class="hlt">freezing</span> (EF) and magnetically disturbed <span class="hlt">freezing</span> (MF), microwave-assisted <span class="hlt">freezing</span> (MWF), and osmo-dehydro-<span class="hlt">freezing</span> (ODF). HPF and UAF can initiate ice nucleation rapidly, leading to uniform distribution of ice crystals and the control of their size and shape. Specifically, the former is focused on increasing the degree of supercooling, whereas the latter aims to decrease it. Direct current electric <span class="hlt">freezing</span> (DC-EF) and alternating current electric <span class="hlt">freezing</span> (AC-EF) exhibit different effects on ice nucleation. DC-EF can promote ice nucleation and AC-EF has the opposite effect. Furthermore, ODF has been successfully used for <span class="hlt">freezing</span> various vegetables and fruit. MWF cannot control the nucleation temperature, but can decrease supercooling degree, thus decreasing the size of ice crystals. The heat and mass transfer processes during ODF have been investigated experimentally and modeled mathematically. More studies should be carried out to understand the effects of these technologies on food <span class="hlt">freezing</span> process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1337643-ordering-pathway-block-copolymers-under-dynamic-thermal-gradients-studied-situ-gisaxs','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1337643-ordering-pathway-block-copolymers-under-dynamic-thermal-gradients-studied-situ-gisaxs"><span>Ordering pathway of block copolymers under dynamic thermal <span class="hlt">gradients</span> studied by in situ GISAXS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Samant, Saumil; Strzalka, Joseph; Yager, Kevin G.; ...</p> <p>2016-10-31</p> <p>Dynamic thermal <span class="hlt">gradient</span>-based processes for directed self-assembly of block copolymer (BCP) thin films such as cold zone annealing (CZA) have demonstrated much potential for rapidly fabricating highly ordered patterns of BCP domains with facile orientation control. As a demonstration, hexagonally packed predominantly <span class="hlt">vertical</span> cylindrical morphology, technologically relevant for applications such as membranes and lithography, was achieved in 1 μm thick cylinder-forming PS-b-PMMA (cBCP) films by applying sharp thermal <span class="hlt">gradients</span> (CZA-Sharp) at optimum sample sweep rates. A thorough understanding of the molecular level mechanisms and pathways of the BCP ordering that occur during this CZA-S process is presented, useful to fullymore » exploit the potential of CZA-S for large-scale BCP-based device fabrication. To that end, we developed a customized CZA-S assembly to probe the dynamic structure evolution and ordering of the PS-b-PMMA cBCP film in situ as it undergoes the CZA-S process using the grazing incidence small-angle X-ray scattering (GISAXS) technique. Four distinct regimes of BCP ordering were observed within the <span class="hlt">gradient</span> that include microphase separation from an “as cast” unordered state (Regime I), evolution of <span class="hlt">vertical</span> cylinders under a thermally imposed strain <span class="hlt">gradient</span> (Regime II), reorientation of a fraction of cylinders due to preferential substrate interactions (Regime III), and finally grain-coarsening on the cooling edge (Regime IV). The ordering pathway in the different regimes is further described within the framework of an energy landscape. A novel aspect of this study is the identification of a grain-coarsening regime on the cooling edge of the <span class="hlt">gradient</span>, previously obscure in zone annealing studies of BCPs. Furthermore, such insights into the development of highly ordered BCP nanostructures under template-free thermal <span class="hlt">gradient</span> fields can potentially have important ramifications in the field of BCP-directed self-assembly and self</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28923767','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28923767"><span>Shrinkage of spray-<span class="hlt">freeze</span>-dried microparticles of pure protein for ballistic injection by manipulation of <span class="hlt">freeze</span>-drying cycle.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Straller, Georg; Lee, Geoffrey</p> <p>2017-10-30</p> <p>Spray-<span class="hlt">freeze</span>-drying was used to produce shrivelled, partially-collapsed microparticles of pure proteins that may be suitable for use in a ballistic injector. Various modifications of the <span class="hlt">freeze</span> drying cycle were examined for their effects on collapse of the pure protein microparticles. The use of annealing at a shelf temperature of up to +10°C resulted in no visible particle shrinkage. This was because of the high T g ' of the pure protein. Inclusion of trehalose or sucrose led to particle shrinkage because of the plasticizing effects of the disaccharides on the protein. Only by extending the duration of primary drying from 240 to 2745min at shelf temperatures in the range -12 to -8°C were shrivelled, wrinkled particles of bSA and bCA of reduced porosity obtained. Manipulation of the <span class="hlt">freeze</span>-drying cycle used for SFD can therefore be used to modify particle morphology and increase particle density. Copyright © 2017 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.B21N..05R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.B21N..05R"><span><span class="hlt">Freeze</span>-Thaw Cycles and Soil Biogeochemistry: Implications for Greenhouse Gas emission</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rezanezhad, F.; Milojevic, T.; Oh, D. H.; Parsons, C. T.; Smeaton, C. M.; Van Cappellen, P.</p> <p>2016-12-01</p> <p><span class="hlt">Freeze</span>-thaw cycles represent a major natural climate forcing acting on soils at middle and high latitudes. Repeated <span class="hlt">freezing</span> and thawing of soils changes their physical properties, geochemistry, and microbial community structure, which together govern the biogeochemical cycling of carbon and nutrients. In this presentation, we focus on how <span class="hlt">freeze</span>-thaw cycles regulate carbon and nitrogen cycling and how these transformations influence greenhouse gas (GHG) fluxes. We present a novel approach, which combines the acquisition of physical and chemical data in a newly developed experimental soil column system. This system simulates realistic soil temperature profiles during <span class="hlt">freeze</span>-thaw cycles. A high-resolution, Multi-Fiber Optode (MuFO) microsensor technique was used to detect oxygen (O2) continuously in the column at multiple depths. Surface and subsurface changes to gas and aqueous phase chemistry were measured to delineate the pathways and quantify soil respiration rates during <span class="hlt">freeze</span>-thaw cycles. The results indicate that the time-dependent release of GHG from the soil surface is influenced by a combination of two key factors. Firstly, fluctuations in temperature and O2 availability affect soil biogeochemical activity and GHG production. Secondly, the recurrent development of a physical ice barrier prevents exchange of gaseous compounds between the soil and atmosphere during <span class="hlt">freezing</span> conditions; removal of this barrier during thaw conditions increases GHG fluxes. During <span class="hlt">freezing</span>, O2 levels in the unsaturated zone decreased due to restricted gas exchange with the atmosphere. As the soil thawed, O2 penetrated deeper into the soil enhancing the aerobic mineralization of organic carbon and nitrogen. Additionally, with the onset of thawing a pulse of gas flux occurred, which is attributed to the build-up of respiratory gases in the pore space during <span class="hlt">freezing</span>. The latter implies enhanced anaerobic respiration as O2 supply ceases when the upper soil layer <span class="hlt">freezes</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011TRACE..24..323M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011TRACE..24..323M"><span>Alcohol Brine <span class="hlt">Freezing</span> of Japanese Horse Mackerel (Trachurus japonicus) for Raw Consumption</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maeda, Toshimichi; Yuki, Atsuhiko; Sakurai, Hiroshi; Watanabe, Koichiro; Itoh, Nobuo; Inui, Etsuro; Seike, Kazunori; Mizukami, Yoichi; Fukuda, Yutaka; Harada, Kazuki</p> <p></p> <p>In order to test the possible application of alcohol brine <span class="hlt">freezing</span> to Japanese horse mackerel (Trachurus japonicus) for raw consumption, the quality and taste of fish frozen by direct immersion in 60% ethanol brine at -20, -25 and -30°C was compared with those by air <span class="hlt">freezing</span> and fresh fish without <span class="hlt">freezing</span>. Cracks were not found during the <span class="hlt">freezing</span>. Smell of ethanol did not remain. K value, an indicator of freshness, of fish frozen in alcohol brine was less than 8.3%, which was at the same level as those by air <span class="hlt">freezing</span> and fresh fish. Oxidation of lipid was at the same level as air <span class="hlt">freezing</span> does, and lower than that of fresh fish. The pH of fish frozen in alcohol brine at -25 and -30°C was 6.5 and 6.6, respectively, which were higher than that by air <span class="hlt">freezing</span> and that of fresh fish. Fish frozen in alcohol brine was better than that by air and at the same level as fresh fish in total evaluation of sensory tests. These results show that the alcohol brine <span class="hlt">freezing</span> is superior to air <span class="hlt">freezing</span>, and fish frozen in alcohol brine can be a material for raw consumption. The methods of thawing in tap water, cold water, refrigerator, and at room temperature were compared. Thawing in tap water is considered to be convenient due to the short thaw time and the quality of thawed fish that was best among the methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/7924395','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/7924395"><span>Effect of moisture content on the invertase activity of <span class="hlt">freeze</span>-dried S. cerevisiae.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pitombo, R N; Spring, C; Passos, R F; Tonato, M; Vitolo, M</p> <p>1994-08-01</p> <p>The invertase activity of intact Saccharomyces cerevisiae submitted to <span class="hlt">freezing</span>-thawing was affected by pH, the chemical nature of the buffer, and the <span class="hlt">freezing</span> cooling rate (CR), leading in some cases to a complete invertase inactivation (acetate buffer, pH 4.0, CR = 0.5 degree C/min). Once established under adequate <span class="hlt">freezing</span> conditions the invertase activity remained unchanged after <span class="hlt">freeze</span>-drying. Nevertheless, in some cases the cell-growing capability after <span class="hlt">freeze</span>-drying diminished around 70%, mainly if the frozen cell suspension was attained through <span class="hlt">freezing</span> carried out at CR = 0.5 degree C/min. Water sorption isotherms of <span class="hlt">freeze</span>-dried samples (<span class="hlt">freeze</span>-dryer Edwards L-4KR; 30 degrees C and 0.1 mB) were determined at 10 and 25 degrees C. The monolayer moisture content (MMC) at each temperature (12.7 and 3.71 for 10 and 25 degrees C, respectively) was calculated from isotherms by applying BET and GAB models. <span class="hlt">Freeze</span>-dried yeast with water activity (Aw) between 0 and 0.33 (about the MMC value) maintained at 25 degrees C for 235 days and at 89 degrees C for 15 min retained at least 85% of its original invertase activity (IA), whereas samples with Aw > MMC lost at least 60% of its IA. X ray diffraction showed that the <span class="hlt">freeze</span>-dried cake before and after storage presented an amorphous structure.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27003129','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27003129"><span><span class="hlt">Freezing</span>-induced uptake of trehalose into mammalian cells facilitates cryopreservation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Miao; Oldenhof, Harriëtte; Sieme, Harald; Wolkers, Willem F</p> <p>2016-06-01</p> <p>The aim of this study was to investigate if membrane-impermeable molecules are taken up by fibroblasts when exposing the cells to membrane phase transitions and/or <span class="hlt">freezing</span>-induced osmotic forces. The membrane-impermeable fluorescent dye lucifer yellow (LY) was used to visualize and quantify uptake during endocytosis, and after <span class="hlt">freezing</span>-thawing. In addition, trehalose uptake after <span class="hlt">freezing</span> and thawing was studied. Fourier transform infrared spectroscopic studies showed that fibroblasts display a minor non-cooperative phase transition during cooling at suprazero temperatures, whereas cells display strong highly cooperative fluid-to-gel membrane phase transitions during <span class="hlt">freezing</span>, both in the absence and presence of protectants. Cells do not show uptake of LY upon passing the suprazero membrane phase transition at 30-10°C, whereas after <span class="hlt">freezing</span> and thawing cells show intracellular LY equally distributed within the cell. Both, LY and trehalose are taken up by fibroblasts after <span class="hlt">freezing</span> and thawing with loading efficiencies approaching 50%. When using 250 mM extracellular trehalose during cryopreservation, intracellular concentrations greater than 100 mM were determined after thawing. A plot of cryosurvival versus the cooling rate showed a narrow inverted-'U'-shaped curve with an optimal cooling rate of 40°C min(-1). Diluting cells cryopreserved with trehalose in isotonic cell culture medium resulted in a loss of cell viability, which was attributed to intracellular trehalose causing an osmotic imbalance. Taken together, mammalian cells can be loaded with membrane-impermeable compounds, including the protective agent trehalose, by subjecting the cells to <span class="hlt">freezing</span>-induced osmotic stress. Copyright © 2016 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29139338','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29139338"><span><span class="hlt">Freeze</span>-drying of silica nanoparticles: redispersibility toward nanomedicine applications.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Picco, Agustin S; Ferreira, Larissa F; Liberato, Michelle S; Mondo, Gabriela B; Cardoso, Mateus B</p> <p>2018-01-01</p> <p>To study <span class="hlt">freeze</span>-drying of silica nanoparticles (SiO 2 NPs) in order to find suitable conditions to produce lyophilized powders with no aggregation after resuspension and storage. SiO 2 NPs were synthesized using a Stöber-based procedure, and characterized by scanning electron microscopy, dynamic light scattering and nitrogen adsorption/desorption isotherms. SiO 2 NPs hydrodynamic diameters were compared prior and after <span class="hlt">freeze</span>-drying in the presence/absence of carbohydrate protectants. Glucose was found to be the most suitable protectant against the detrimental effects of lyophilization. The minimum concentration of carbohydrate required to effectively protect SiO 2 NPs from aggregation during <span class="hlt">freeze</span>-drying is influenced by the nanoparticle's size and texture. Negligible aggregation was observed during storage. Carbohydrates can be used during SiO 2 NPs <span class="hlt">freeze</span>-drying process to obtain redispersable solids that maintain original sizes without residual aggregation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4583428','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4583428"><span><span class="hlt">Vertical</span> and Horizontal Vegetation Structure across Natural and Modified Habitat Types at Mount Kilimanjaro</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rutten, Gemma; Ensslin, Andreas; Hemp, Andreas; Fischer, Markus</p> <p>2015-01-01</p> <p>In most habitats, vegetation provides the main structure of the environment. This complexity can facilitate biodiversity and ecosystem services. Therefore, measures of vegetation structure can serve as indicators in ecosystem management. However, many structural measures are laborious and require expert knowledge. Here, we used consistent and convenient measures to assess vegetation structure over an exceptionally broad elevation <span class="hlt">gradient</span> of 866–4550m above sea level at Mount Kilimanjaro, Tanzania. Additionally, we compared (human)-modified habitats, including maize fields, traditionally managed home gardens, grasslands, commercial coffee farms and logged and burned forests with natural habitats along this elevation <span class="hlt">gradient</span>. We distinguished <span class="hlt">vertical</span> and horizontal vegetation structure to account for habitat complexity and heterogeneity. <span class="hlt">Vertical</span> vegetation structure (assessed as number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) displayed a unimodal elevation pattern, peaking at intermediate elevations in montane forests, whereas horizontal structure (assessed as coefficient of variation of number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) was lowest at intermediate altitudes. Overall, <span class="hlt">vertical</span> structure was consistently lower in modified than in natural habitat types, whereas horizontal structure was inconsistently different in modified than in natural habitat types, depending on the specific structural measure and habitat type. Our study shows how <span class="hlt">vertical</span> and horizontal vegetation structure can be assessed efficiently in various habitat types in tropical mountain regions, and we suggest to apply this as a tool for informing future biodiversity and ecosystem service studies. PMID:26406985</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26406985','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26406985"><span><span class="hlt">Vertical</span> and Horizontal Vegetation Structure across Natural and Modified Habitat Types at Mount Kilimanjaro.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rutten, Gemma; Ensslin, Andreas; Hemp, Andreas; Fischer, Markus</p> <p>2015-01-01</p> <p>In most habitats, vegetation provides the main structure of the environment. This complexity can facilitate biodiversity and ecosystem services. Therefore, measures of vegetation structure can serve as indicators in ecosystem management. However, many structural measures are laborious and require expert knowledge. Here, we used consistent and convenient measures to assess vegetation structure over an exceptionally broad elevation <span class="hlt">gradient</span> of 866-4550 m above sea level at Mount Kilimanjaro, Tanzania. Additionally, we compared (human)-modified habitats, including maize fields, traditionally managed home gardens, grasslands, commercial coffee farms and logged and burned forests with natural habitats along this elevation <span class="hlt">gradient</span>. We distinguished <span class="hlt">vertical</span> and horizontal vegetation structure to account for habitat complexity and heterogeneity. <span class="hlt">Vertical</span> vegetation structure (assessed as number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) displayed a unimodal elevation pattern, peaking at intermediate elevations in montane forests, whereas horizontal structure (assessed as coefficient of variation of number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) was lowest at intermediate altitudes. Overall, <span class="hlt">vertical</span> structure was consistently lower in modified than in natural habitat types, whereas horizontal structure was inconsistently different in modified than in natural habitat types, depending on the specific structural measure and habitat type. Our study shows how <span class="hlt">vertical</span> and horizontal vegetation structure can be assessed efficiently in various habitat types in tropical mountain regions, and we suggest to apply this as a tool for informing future biodiversity and ecosystem service studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JAG...128..131G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JAG...128..131G"><span>Detection, localization and classification of multiple dipole-like magnetic sources using magnetic <span class="hlt">gradient</span> tensor data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gang, Yin; Yingtang, Zhang; Hongbo, Fan; Zhining, Li; Guoquan, Ren</p> <p>2016-05-01</p> <p>We have developed a method for automatic detection, localization and classification (DLC) of multiple dipole sources using magnetic <span class="hlt">gradient</span> tensor data. First, we define modified tilt angles to estimate the approximate horizontal locations of the multiple dipole-like magnetic sources simultaneously and detect the number of magnetic sources using a fixed threshold. Secondly, based on the isotropy of the normalized source strength (NSS) response of a dipole, we obtain accurate horizontal locations of the dipoles. Then the <span class="hlt">vertical</span> locations are calculated using magnitude magnetic transforms of magnetic <span class="hlt">gradient</span> tensor data. Finally, we invert for the magnetic moments of the sources using the measured magnetic <span class="hlt">gradient</span> tensor data and forward model. Synthetic and field data sets demonstrate effectiveness and practicality of the proposed method.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3202940','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3202940"><span>The origins and evolution of <span class="hlt">freeze</span>-etch electron microscopy</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Heuser, John E.</p> <p>2011-01-01</p> <p>The introduction of the Balzers <span class="hlt">freeze</span>-fracture machine by Moor in 1961 had a much greater impact on the advancement of electron microscopy than he could have imagined. Devised originally to circumvent the dangers of classical thin-section techniques, as well as to provide unique en face views of cell membranes, <span class="hlt">freeze</span>-fracturing proved to be crucial for developing modern concepts of how biological membranes are organized and proved that membranes are bilayers of lipids within which proteins float and self-assemble. Later, when <span class="hlt">freeze</span>-fracturing was combined with methods for <span class="hlt">freezing</span> cells that avoided the fixation and cryoprotection steps that Moor still had to use to prepare the samples for his original invention, it became a means for capturing membrane dynamics on the millisecond time-scale, thus allowing a deeper understanding of the functions of biological membranes in living cells as well as their static ultrastructure. Finally, the realization that unfixed, non-cryoprotected samples could be deeply vacuum-etched or even <span class="hlt">freeze</span>-dried after <span class="hlt">freeze</span>-fracturing opened up a whole new way to image all the other molecular components of cells besides their membranes and also provided a powerful means to image the interactions of all the cytoplasmic components with the various membranes of the cell. The purpose of this review is to outline the history of these technical developments, to describe how they are being used in electron microscopy today and to suggest how they can be improved in order to further their utility for biological electron microscopy in the future. PMID:21844598</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/863562','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/863562"><span>Method of <span class="hlt">freezing</span> living cells and tissues with improved subsequent survival</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Senkan, Selim M.; Hirsch, Gerald P.</p> <p>1980-01-01</p> <p>This invention relates to an improved method for <span class="hlt">freezing</span> red blood cells, ther living cells, or tissues with improved subsequent survival, wherein constant-volume <span class="hlt">freezing</span> is utilized that results in significantly improved survival compared with constant-pressure <span class="hlt">freezing</span>; optimization is attainable through the use of different vessel geometries, cooling baths and warming baths, and sample concentrations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19640137','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19640137"><span>Model for heat and mass transfer in <span class="hlt">freeze</span>-drying of pellets.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Trelea, Ioan Cristian; Passot, Stéphanie; Marin, Michèle; Fonseca, Fernanda</p> <p>2009-07-01</p> <p>Lyophilizing frozen pellets, and especially spray <span class="hlt">freeze</span>-drying, have been receiving growing interest. To design efficient and safe <span class="hlt">freeze</span>-drying cycles, local temperature and moisture content in the product bed have to be known, but both are difficult to measure in the industry. Mathematical modeling of heat and mass transfer helps to determine local <span class="hlt">freeze</span>-drying conditions and predict effects of operation policy, and equipment and recipe changes on drying time and product quality. Representative pellets situated at different positions in the product slab were considered. One-dimensional transfer in the slab and radial transfer in the pellets were assumed. Coupled heat and vapor transfer equations between the temperature-controlled shelf, the product bulk, the sublimation front inside the pellets, and the chamber were established and solved numerically. The model was validated based on bulk temperature measurement performed at two different locations in the product slab and on partial vapor pressure measurement in the <span class="hlt">freeze</span>-drying chamber. Fair agreement between measured and calculated values was found. In contrast, a previously developed model for compact product layer was found inadequate in describing <span class="hlt">freeze</span>-drying of pellets. The developed model represents a good starting basis for studying <span class="hlt">freeze</span>-drying of pellets. It has to be further improved and validated for a variety of product types and <span class="hlt">freeze</span>-drying conditions (shelf temperature, total chamber pressure, pellet size, slab thickness, etc.). It could be used to develop <span class="hlt">freeze</span>-drying cycles based on product quality criteria such as local moisture content and glass transition temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001HMT....37...67D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001HMT....37...67D"><span>Heat and mass transfer analogy for condensation of humid air in a <span class="hlt">vertical</span> channel</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Desrayaud, G.; Lauriat, G.</p> <p></p> <p>This study examines energy transport associated with liquid film condensation in natural convection flows driven by differences in density due to temperature and concentration <span class="hlt">gradients</span>. The condensation problem is based on the thin-film assumptions. The most common compositional <span class="hlt">gradient</span>, which is encountered in humid air at ambient temperature is considered. A steady laminar Boussinesq flow of an ideal gas-vapor mixture is studied for the case of a <span class="hlt">vertical</span> parallel plate channel. New correlations for the latent and sensible Nusselt numbers are established, and the heat and mass transfer analogy between the sensible Nusselt number and Sherwood number is demonstrated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4858659','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4858659"><span>Cognitive Contributions to <span class="hlt">Freezing</span> of Gait in Parkinson Disease: Implications for Physical Rehabilitation</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>King, Laurie A.; Cohen, Rajal G.; Horak, Fay B.</p> <p>2016-01-01</p> <p>People with Parkinson disease (PD) who show <span class="hlt">freezing</span> of gait also have dysfunction in cognitive domains that interact with mobility. Specifically, <span class="hlt">freezing</span> of gait is associated with executive dysfunction involving response inhibition, divided attention or switching attention, and visuospatial function. The neural control impairments leading to <span class="hlt">freezing</span> of gait have recently been attributed to higher-level, executive and attentional cortical processes involved in coordinating posture and gait rather than to lower-level, sensorimotor impairments. To date, rehabilitation for <span class="hlt">freezing</span> of gait primarily has focused on compensatory mobility training to overcome <span class="hlt">freezing</span> events, such as sensory cueing and voluntary step planning. Recently, a few interventions have focused on restitutive, rather than compensatory, therapy. Given the documented impairments in executive function specific to patients with PD who <span class="hlt">freeze</span> and increasing evidence of overlap between cognitive and motor function, incorporating cognitive challenges with mobility training may have important benefits for patients with <span class="hlt">freezing</span> of gait. Thus, a novel theoretical framework is proposed for exercise interventions that jointly address both the specific cognitive and mobility challenges of people with PD who <span class="hlt">freeze</span>. PMID:26381808</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040090097&hterms=food+processing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dfood%2Bprocessing','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040090097&hterms=food+processing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dfood%2Bprocessing"><span>Folic acid content in thermostabilized and <span class="hlt">freeze</span>-dried space shuttle foods</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lane, H. W.; Nillen, J. L.; Kloeris, V. L.</p> <p>1995-01-01</p> <p>This study was designed to determine whether <span class="hlt">freeze</span>-dried and thermostabilized foods on a space shuttle contain adequate folate and to investigate any effects of <span class="hlt">freeze</span>-drying on folacin. Frozen vegetables were analyzed after three states of processing: thawed; cooked; and rehydrated. Thermostabilized items were analyzed as supplied with no further processing. Measurable folate decreased in some <span class="hlt">freeze</span>-dried vegetables and increased in others. Folacin content of thermostabilized food items was comparable with published values. We concluded that although the folacin content of some <span class="hlt">freeze</span>-dried foods was low, adequate folate is available from the shuttle menu to meet RDA guidelines.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.B51C0422M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.B51C0422M"><span>Waveform LiDAR across forest biomass <span class="hlt">gradients</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Montesano, P. M.; Nelson, R. F.; Dubayah, R.; Sun, G.; Ranson, J.</p> <p>2011-12-01</p> <p>Detailed information on the quantity and distribution of aboveground biomass (AGB) is needed to understand how it varies across space and changes over time. Waveform LiDAR data is routinely used to derive the heights of scattering elements in each illuminated footprint, and the <span class="hlt">vertical</span> structure of vegetation is related to AGB. Changes in LiDAR waveforms across vegetation structure <span class="hlt">gradients</span> can demonstrate instrument sensitivity to land cover transitions. A close examination of LiDAR waveforms in footprints across a forest <span class="hlt">gradient</span> can provide new insight into the relationship of vegetation structure and forest AGB. In this study we use field measurements of individual trees within Laser Vegetation Imaging Sensor (LVIS) footprints along transects crossing forest to non-forest <span class="hlt">gradients</span> to examine changes in LVIS waveform characteristics at sites with low (< 50Mg/ha) AGB. We relate field AGB measurements to original and adjusted LVIS waveforms to detect the forest AGB interval along a forest - non-forest transition in which the LVIS waveform lose the ability to discern differences in AGB. Our results help identify the lower end the forest biomass range that a ~20m footprint waveform LiDAR can detect, which can help infer accumulation of biomass after disturbances and during forest expansion, and which can guide the use of LiDAR within a multi-sensor fusion biomass mapping approach.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011TRACE..15..213S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011TRACE..15..213S"><span><span class="hlt">Freezing</span> of Water Droplet due to Evaporation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Satoh, Isao; Fushinobu, Kazuyoshi; Hashimoto, Yu</p> <p></p> <p>In this study, the feasibility of cooling/<span class="hlt">freezing</span> of phase change.. materials(PCMs) due to evaporation for cold storage systems was experimentally examined. A pure water was used as the test PCM, since the latent heat due to evaporation of water is about 7 times larger than that due to <span class="hlt">freezing</span>. A water droplet, the diameter of which was 1-4 mm, was suspended in a test cell by a fine metal wire (O. D.= 100μm),and the cell was suddenly evacuated up to the pressure lower than the triple-point pressure of water, so as to enhance the evaporation from the water surface. Temperature of the droplet was measured by a thermocouple, and the cooling/<span class="hlt">freezing</span> behavior and the temperature profile of the droplet surface were captured by using a video camera and an IR thermo-camera, respectively. The obtained results showed that the water droplet in the evacuated cell is effectively cooled by the evaporation of water itself, and is frozen within a few seconds through remarkable supercooling state. When the initial temperature of the droplet is slightly higher than the room temperature, boiling phenomena occur in the droplet simultaneously with the <span class="hlt">freezing</span> due to evaporation. Under such conditions, it was shown that the degree of supercooling of the droplet is reduced by the bubbles generated in the droplet.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20599885','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20599885"><span><span class="hlt">Freezing</span> in the Antarctic limpet, Nacella concinna.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hawes, T C; Worland, M R; Bale, J S</p> <p>2010-08-01</p> <p>The process of organismal <span class="hlt">freezing</span> in the Antarctic limpet, Nacella concinna, is complicated by molluscan biology. Internal ice formation is, in particular, mediated by two factors: (a) the provision of an inoculative target for ice formation in the exposed mucus-secreting foot; and (b) osmoconformity to the marine environment. With regard to the first, direct observations of the independent <span class="hlt">freezing</span> of pedal mucus support the hypothesis that internal ice formation is delayed by the mucal film. As to the second, ice nucleation parametrics of organismal tissue (head, midgut, gonad, foot) and mucus in both inter- and subtidal populations were characterized by high melting points (range=-4.61 to -6.29 degrees C), with only c.50% of a given sample osmotically active. At this stage it would be premature to ascribe a cryo-adaptive function to the mucus as the protective effects are more readily attributed to the physical properties of the secretion (i.e. viscosity) and their corresponding effects on the rate of heat transfer. As it is difficult to thermally distinguish between the <span class="hlt">freezing</span> of mucus and the rest of the animal, the question as to whether it is tolerant of internal as well as external ice formation remains problematic, although it may be well suited to the osmotic stresses of organismal <span class="hlt">freezing</span>. (c) 2010 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA33A2583S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA33A2583S"><span>Atmospheric gravity waves with small <span class="hlt">vertical</span>-to-horizotal wavelength ratios</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Song, I. S.; Jee, G.; Kim, Y. H.; Chun, H. Y.</p> <p>2017-12-01</p> <p>Gravity wave modes with small <span class="hlt">vertical</span>-to-horizontal wavelength ratios of an order of 10-3 are investigated through the systematic scale analysis of governing equations for gravity wave perturbations embedded in the quasi-geostrophic large-scale flow. These waves can be categorized as acoustic gravity wave modes because their total energy is given by the sum of kinetic, potential, and elastic parts. It is found that these waves can be forced by density fluctuations multiplied by the horizontal <span class="hlt">gradients</span> of the large-scale pressure (geopotential) fields. These theoretical findings are evaluated using the results of a high-resolution global model (Specified Chemistry WACCM with horizontal resolution of 25 km and <span class="hlt">vertical</span> resolution of 600 m) by computing the density-related gravity-wave forcing terms from the modeling results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14520570','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14520570"><span>Repeated <span class="hlt">freeze</span>-thaw cycles induce embolism in drought stressed conifers (Norway spruce, stone pine).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mayr, Stefan; Gruber, Andreas; Bauer, Helmut</p> <p>2003-07-01</p> <p><span class="hlt">Freezing</span> and thawing lead to xylem embolism when gas bubbles caused by ice formation expand during the thaw process. However, previous experimental studies indicated that conifers are resistant to <span class="hlt">freezing</span>-induced embolism, unless xylem pressure becomes very negative during the <span class="hlt">freezing</span>. In this study, we show that conifers experienced <span class="hlt">freezing</span>-induced embolism when exposed to repeated <span class="hlt">freeze</span>-thaw cycles and simultaneously to drought. Simulating conditions at the alpine timberline (128 days with <span class="hlt">freeze</span>-thaw events and thawing rates of up to 9.5 K h(-1) in the xylem of exposed twigs during winter), young trees of Norway spruce [Picea abies (L.) Karst.] and stone pine (Pinus cembra L.) were exposed to 50 and 100 <span class="hlt">freeze</span>-thaw cycles. This treatment caused a significant increase in embolism rates in drought-stressed samples. Upon 100 <span class="hlt">freeze</span>-thaw cycles, vulnerability thresholds (50% loss of conductivity) were shifted 1.8 MPa (Norway spruce) and 0.8 MPa (stone pine) towards less negative water potentials. The results demonstrate that <span class="hlt">freeze</span>-thaw cycles are a possible reason for winter-embolism in conifers observed in several field studies. <span class="hlt">Freezing</span>-induced embolism may contribute to the altitudinal limits of conifers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001SPIE.4301...52B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001SPIE.4301...52B"><span>Segmentation of human face using <span class="hlt">gradient</span>-based approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baskan, Selin; Bulut, M. Mete; Atalay, Volkan</p> <p>2001-04-01</p> <p>This paper describes a method for automatic segmentation of facial features such as eyebrows, eyes, nose, mouth and ears in color images. This work is an initial step for wide range of applications based on feature-based approaches, such as face recognition, lip-reading, gender estimation, facial expression analysis, etc. Human face can be characterized by its skin color and nearly elliptical shape. For this purpose, face detection is performed using color and shape information. Uniform illumination is assumed. No restrictions on glasses, make-up, beard, etc. are imposed. Facial features are extracted using the <span class="hlt">vertically</span> and horizontally oriented <span class="hlt">gradient</span> projections. The <span class="hlt">gradient</span> of a minimum with respect to its neighbor maxima gives the boundaries of a facial feature. Each facial feature has a different horizontal characteristic. These characteristics are derived by extensive experimentation with many face images. Using fuzzy set theory, the similarity between the candidate and the feature characteristic under consideration is calculated. <span class="hlt">Gradient</span>-based method is accompanied by the anthropometrical information, for robustness. Ear detection is performed using contour-based shape descriptors. This method detects the facial features and circumscribes each facial feature with the smallest rectangle possible. AR database is used for testing. The developed method is also suitable for real-time systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992IJHMT..35.1003N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992IJHMT..35.1003N"><span>Double-diffusive boundary layers along <span class="hlt">vertical</span> free surfaces</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Napolitano, L. G.; Viviani, A.; Savino, R.</p> <p>1992-05-01</p> <p>This paper deals with double-diffusive (or thermosolutal) combined free convection, i.e., free convection due to buoyant forces (natural convection) and surface tension <span class="hlt">gradients</span> (Marangoni convection), which are generated by volume differences and surface <span class="hlt">gradients</span> of temperature and solute concentration. Attention is focused on boundary layers that form along a <span class="hlt">vertical</span> liquid-gas interface, when the appropriately defined nondimensional characteristic transport numbers are large enough, in problems of thermosolutal natural and Marangoni convection, such as buoyancy and surface tension driven flows in differentially heated open cavities and liquid bridges. Classes of similar solutions are derived for each class of convection on the basis of a rigorous order of magnitude analysis. Velocity, temperature and concentration profiles are reported in the similarity plane; flow and transport properties at the liquid-gas interface (interfacial velocity, heat and mass transfer bulk coefficients) are obtained for a wide range of Prandtl and Schmidt numbers and different values of the similarity parameter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=327407','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=327407"><span>A note on the effective evaluation height for flux-<span class="hlt">gradient</span> relationships and its application to herbicide fluxes</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Volatilization represents a significant loss pathway for many pesticides, herbicides and other agrochemicals. One common method for measuring the volatilization of agrochemicals is the flux-<span class="hlt">gradient</span> method. Using this method, the chemical flux is estimated as the product of the <span class="hlt">vertical</span> concentratio...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28222256','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28222256"><span>Dynamic Melting of <span class="hlt">Freezing</span> Droplets on Ultraslippery Superhydrophobic Surfaces.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chu, Fuqiang; Wu, Xiaomin; Wang, Lingli</p> <p>2017-03-08</p> <p>Condensed droplet <span class="hlt">freezing</span> and <span class="hlt">freezing</span> droplet melting phenomena on the prepared ultraslippery superhydrophobic surface were observed and discussed in this study. Although the <span class="hlt">freezing</span> delay performance of the surface is common, the melting of the <span class="hlt">freezing</span> droplets on the surface is quite interesting. Three self-propelled movements of the melting droplets (ice- water mixture) were found including the droplet rotating, the droplet jumping, and the droplet sliding. The melting droplet rotating, which means that the melting droplet rotates spontaneously on the superhydrophobic surface like a spinning top, is first reported in this study and may have some potential applications in various engineering fields. The melting droplet jumping and sliding are similar to those occurring during condensation but have larger size scale and motion scale, as the melting droplets have extra-large specific surface area with much more surface energy available. These self-propelled movements make all the melting droplets on the superhydrophobic surface dynamic, easily removed, which may be promising for the anti-icing/frosting applications.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4816275','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4816275"><span>Transcriptome Analysis of Spartina pectinata in Response to <span class="hlt">Freezing</span> Stress</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nah, Gyoungju; Lee, Moonsub; Kim, Do-Soon; Rayburn, A. Lane; Voigt, Thomas; Lee, D. K.</p> <p>2016-01-01</p> <p>Prairie cordgrass (Spartina pectinata), a perennial C4 grass native to the North American prairie, has several distinctive characteristics that potentially make it a model crop for production in stressful environments. However, little is known about the transcriptome dynamics of prairie cordgrass despite its unique <span class="hlt">freezing</span> stress tolerance. Therefore, the purpose of this work was to explore the transcriptome dynamics of prairie cordgrass in response to <span class="hlt">freezing</span> stress at -5°C for 5 min and 30 min. We used a RNA-sequencing method to assemble the S. pectinata leaf transcriptome and performed gene-expression profiling of the transcripts under <span class="hlt">freezing</span> treatment. Six differentially expressed gene (DEG) groups were categorized from the profiling. In addition, two major consecutive orders of gene expression were observed in response to <span class="hlt">freezing</span>; the first being the acute up-regulation of genes involved in plasma membrane modification, calcium-mediated signaling, proteasome-related proteins, and transcription regulators (e.g., MYB and WRKY). The follow-up and second response was of genes involved in encoding the putative anti-<span class="hlt">freezing</span> protein and the previously known DNA and cell-damage-repair proteins. Moreover, we identified the genes involved in epigenetic regulation and circadian-clock expression. Our results indicate that <span class="hlt">freezing</span> response in S. pectinata reflects dynamic changes in rapid-time duration, as well as in metabolic, transcriptional, post-translational, and epigenetic regulation. PMID:27032112</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4662221','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4662221"><span>Quality Evaluation of Pork with Various <span class="hlt">Freezing</span> and Thawing Methods</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2014-01-01</p> <p>In this study, the physicochemical and sensory quality characteristics due to the influence of various thawing methods on electro-magnetic and air blast frozen pork were examined. The packaged pork samples, which were frozen by air blast <span class="hlt">freezing</span> at −45℃ or electro-magnetic <span class="hlt">freezing</span> at −55℃, were thawed using 4 different methods: refrigeration (4±1℃), room temperature (RT, 25℃), cold water (15℃), and microwave (2450 MHz). Analyses were carried out to determine the drip and cooking loss, water holding capacity (WHC), moisture content and sensory evaluation. Frozen pork thawed in a microwave indicated relatively less thawing loss (0.63-1.24%) than the other thawing methods (0.68-1.38%). The cooking loss after electro-magnetic <span class="hlt">freezing</span> indicated 37.4% by microwave thawing, compared with 32.9% by refrigeration, 36.5% by RT, and 37.2% by cold water in ham. The thawing of samples frozen by electro-magnetic <span class="hlt">freezing</span> showed no significant differences between the methods used, while the moisture content was higher in belly thawed by microwave (62.0%) after electro-magnetic <span class="hlt">freezing</span> than refrigeration (54.8%), RT (61.3%), and cold water (61.1%). The highest overall acceptability was shown for microwave thawing after electro-magnetic <span class="hlt">freezing</span> but there were no significant differences compared to that of the other samples. PMID:26761493</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950037899&hterms=vertical+height&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dvertical%2Bheight','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950037899&hterms=vertical+height&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dvertical%2Bheight"><span><span class="hlt">Vertical</span> velocity in oceanic convection off tropical Australia</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lucas, Christopher; Zipser, Edward J.; Lemone, Margaret A.</p> <p>1994-01-01</p> <p>Time series of 1-Hz <span class="hlt">vertical</span> velocity data collected during aircraft penetrations of oceanic cumulonimbus clouds over the western Pacific warm pool as part of the Equatorial Mesoscale Experiment (EMEX) are analyzed for updraft and downdraft events called cores. An updraft core is defined as occurring whenever the <span class="hlt">vertical</span> velocity exceeds 1 m/sec for at least 500 m. A downdraft core is defined analogously. Over 19,000 km of straight and level flight legs are used in the analysis. Five hundred eleven updraft cores and 253 downdraft cores are included in the dataset. Core properties are summarized as distributions of average and maximum <span class="hlt">vertical</span> velocity, diameter, and mass flux in four altitude intervals between 0.2 and 5.8 km. Distributions are approximately lognormal at all levels. Examination of the variation of the statistics with height suggests a maximum in <span class="hlt">vertical</span> velocity between 2 and 3 km; slightly lower or equal <span class="hlt">vertical</span> velocity is indicated at 5 km. Near the <span class="hlt">freezing</span> level, virtual temperature deviations are found to be slightly positive for both updraft and downdraft cores. The excess in updraft cores is much smaller than that predicted by parcel theory. Comparisons with other studies that use the same analysis technique reveal that EMEX cores have approximately the same strength as cores of other oceanic areas, despite warmer sea surface temperatures. Diameter and mass flux are greater than those in the Global Atmospheric Research Program (GATE) but smaller than those in hurricane rainbands. Oceanic cores are much weaker and appear to be slightly smaller than those observed over land during the Thunderstorm Project. The markedly weaker oceanic <span class="hlt">vertical</span> velocities below 5.8 km (compared to the continental cores) cannot be attributed to smaller total convective available potential energy or to very high water loading. Rather, it is suggested that water loading, although less than adiabatic, is more effective in reducing buoyancy of oceanic cores</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22357119','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22357119"><span>Effects of <span class="hlt">freezing</span> on the bactericidal activity of human milk.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Takci, Sahin; Gulmez, Dolunay; Yigit, Sule; Dogan, Ozlem; Dik, Kezban; Hascelik, Gulsen</p> <p>2012-08-01</p> <p>Storage of human milk by <span class="hlt">freezing</span> has been recommended for long-term storage. The present study analyzed the bactericidal activity of human milk on Escherichia coli and Pseudomonas aeruginosa and determined the changes in bactericidal activity following <span class="hlt">freezing</span> at -20°C and -80°C for 1 month and 3 months. Forty-eight milk samples were collected from 48 lactating mothers. Each sample was divided into 10 aliquots. Two of the samples were processed immediately and the others were stored at both -20°C and -80°C until analysis after 1 month and 3 months of <span class="hlt">freezing</span>. All of the fresh milk samples showed bactericidal activity against E coli and P aeruginosa. <span class="hlt">Freezing</span> at -20°C for 1 month did not cause statistically significant alteration in bactericidal activity (P > 0.017), whereas storage for 3 months lowered the degree of bactericidal activity significantly (P < 0.017) against E coli. Bactericidal activity was protected when the samples were stored at -80°C. There was no statistically significant difference in the bactericidal activity of human milk against E coli between <span class="hlt">freezing</span> at -20°C and -80°C for 1 month (P > 0.017); however, when milk was stored for 3 months, -80°C was significantly more protective (P < 0.017). <span class="hlt">Freezing</span> at -20°C and -80°C for 1 month and 3 months did not cause any significant change in bactericidal activity against P aeruginosa (P > 0.05). Storage by <span class="hlt">freezing</span> at -80°C is more appropriate to keep bactericidal capacity of stored human milk >1 month if affordable and available, especially in intensive care settings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015OcScD..12.2073L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015OcScD..12.2073L"><span>The role of <span class="hlt">vertical</span> shear on the horizontal oceanic dispersion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lanotte, A. S.; Corrado, R.; Lacorata, G.; Palatella, L.; Pizzigalli, C.; Schipa, I.; Santoleri, R.</p> <p>2015-09-01</p> <p>The effect of <span class="hlt">vertical</span> shear on the horizontal dispersion properties of passive tracer particles on the continental shelf of South Mediterranean is investigated by means of observative and model data. In-situ current measurements reveal that <span class="hlt">vertical</span> velocity <span class="hlt">gradients</span> in the upper mixed layer decorrelate quite fast (∼ 1 day), whereas basin-scale ocean circulation models tend to overestimate such decorrelation time because of finite resolution effects. Horizontal dispersion simulated by an eddy-permitting ocean model, like, e.g., the Mediterranean Forecasting System, is mosty affected by: (1) unresolved scale motions, and mesoscale motions that are largely smoothed out; (2) poorly resolved time variability of <span class="hlt">vertical</span> velocity profiles in the upper layer. For the case study we have analysed, we show that a suitable use of kinematic parameterisations is helpful to implement realistic statistical features of tracer dispersion in two and three dimensions. The approach here suggested provides a functional tool to control the horizontal spreading of small organisms or substance concentrations, and is thus relevant for marine biology, pollutant dispersion as well as oil spill applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/1013395','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/1013395"><span>Estimating the time of melt onset and <span class="hlt">freeze</span> onset over Arctic sea-ice area using active and passive microwave data</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Belchansky, Gennady I.; Douglas, David C.; Mordvintsev, Ilia N.; Platonov, Nikita G.</p> <p>2004-01-01</p> <p>Accurate calculation of the time of melt onset, <span class="hlt">freeze</span> onset, and melt duration over Arctic sea-ice area is crucial for climate and global change studies because it affects accuracy of surface energy balance estimates. This comparative study evaluates several methods used to estimate sea-ice melt and <span class="hlt">freeze</span> onset dates: (1) the melt onset database derived from SSM/I passive microwave brightness temperatures (Tbs) using Drobot and Anderson's [J. Geophys. Res. 106 (2001) 24033] Advanced Horizontal Range Algorithm (AHRA) and distributed by the National Snow and Ice Data Center (NSIDC); (2) the International Arctic Buoy Program/Polar Exchange at the Sea (IABP/POLES) surface air temperatures (SATs); (3) an elaborated version of the AHRA that uses IABP/POLES to avoid anomalous results (Passive Microwave and Surface Temperature Analysis [PMSTA]); (4) another elaborated version of the AHRA that uses Tb variance to avoid anomalous results (Mean Differences and Standard Deviation Analysis [MDSDA]); (5) Smith's [J. Geophys. Res. 103 (1998) 27753] <span class="hlt">vertically</span> polarized Tb algorithm for estimating melt onset in multiyear (MY) ice (SSM/I 19V–37V); and (6) analyses of concurrent backscattering cross section (σ°) and brightness temperature (Tb) from OKEAN-01 satellite series. Melt onset and <span class="hlt">freeze</span> onset maps were created and compared to understand how the estimates vary between different satellite instruments and methods over different Arctic sea-ice regions. Comparisons were made to evaluate relative sensitivities among the methods to slight adjustments of the Tbcalibration coefficients and algorithm threshold values. Compared to the PMSTA method, the AHRA method tended to estimate significantly earlier melt dates, likely caused by the AHRA's susceptibility to prematurely identify melt onset conditions. In contrast, the IABP/POLES surface air temperature data tended to estimate later melt and earlier <span class="hlt">freeze</span> in all but perennial ice. The MDSDA method was least sensitive to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4000207','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4000207"><span>Intracellular <span class="hlt">Freezing</span> in the Infective Juveniles of Steinernema feltiae: An Entomopathogenic Nematode</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ali, Farman; Wharton, David A.</p> <p>2014-01-01</p> <p>Taking advantage of their optical transparency, we clearly observed the third stage infective juveniles (IJs) of Steinernema feltiae <span class="hlt">freezing</span> under a cryo-stage microscope. The IJs froze when the water surrounding them froze at −2°C and below. However, they avoid inoculative <span class="hlt">freezing</span> at −1°C, suggesting cryoprotective dehydration. <span class="hlt">Freezing</span> was evident as a sudden darkening and cessation of IJs' movement. <span class="hlt">Freeze</span> substitution and transmission electron microscopy confirmed that the IJs of S. feltiae <span class="hlt">freeze</span> intracellularly. Ice crystals were found in every compartment of the body. IJs frozen at high sub-zero temperatures (−1 and −3°C) survived and had small ice crystals. Those frozen at −10°C had large ice crystals and did not survive. However, the pattern of ice formation was not well-controlled and individual nematodes frozen at −3°C had both small and large ice crystals. IJs frozen by plunging directly into liquid nitrogen had small ice crystals, but did not survive. This study thus presents the evidence that S. feltiae is only the second <span class="hlt">freeze</span> tolerant animal, after the Antarctic nematode Panagrolaimus davidi, shown to withstand extensive intracellular <span class="hlt">freezing</span>. PMID:24769523</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1815715M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1815715M"><span><span class="hlt">Vertical</span> profiles of BC direct radiative effect over Italy: high <span class="hlt">vertical</span> resolution data and atmospheric feedbacks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Močnik, Griša; Ferrero, Luca; Castelli, Mariapina; Ferrini, Barbara S.; Moscatelli, Marco; Grazia Perrone, Maria; Sangiorgi, Giorgia; Rovelli, Grazia; D'Angelo, Luca; Moroni, Beatrice; Scardazza, Francesco; Bolzacchini, Ezio; Petitta, Marcello; Cappelletti, David</p> <p>2016-04-01</p> <p> observed below the MH. The radiative power density absorbed into each atmospheric layer was normalized by the layer height to compare measurements taken at different sites with different <span class="hlt">vertical</span> resolutions. The atmospheric absorption of radiative power below the MH ranged from +45.2±5.1 mW/m3 up to +103.3±16.2 mW/m3 and was ~2-3 times higher than above MH. The resulting heating rate was characterized by a <span class="hlt">vertical</span> negative <span class="hlt">gradient</span> with increasing height, from -2.6±0.2 K/(day km) up to -8.3±1.2 K/(day km), exerting a negative feedback on the atmospheric stability over basin valleys, weakening the ground-based thermal inversions and increasing the dispersal conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMMR13A2260C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMMR13A2260C"><span>The observation of the physicochemical change of rock under <span class="hlt">freeze</span>-thawing experiment: CLSM, XRD and ICP analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Choi, J.; Chae, B.; Chon, C.; Jeong, J.</p> <p>2013-12-01</p> <p>Abstract : In order to understand the progress of the physical weathering of rock sample, we managed <span class="hlt">freeze</span>-thawing experiment at temperature of up to 40C from -20C taking into account of South Korea. In this study, the time was held by two hours the temperature of the maximum (40C) and minimum (-20C) and the experiments were carried out at intervals of one hour rising and falling. We have run the experiment about 120 cycle with the cycle of -20C from 40C experiment. We measured the physical properties of rock samples after each 20 cycle has elapsed by using confocal laser scanning microscope (CLSM) and observed changes in roughness of rock samples surface. We also analyzed the mineral of rock sample using the XRD analysis and observing the change in chemical composition of solution used in the experiment by using ICP analysis. Through the above process, we observed physico-chemical changes in the rock sample due to <span class="hlt">freeze</span>-thaw cycles. To analysis of the line roughness parameter we used set by the 10 <span class="hlt">vertical</span> and horizontal cross section line on the surface and surface roughness parameter was analyzed by using the area on the surface. Through such a process, while the <span class="hlt">freeze</span>-thawing experiment is advanced, it was studied how the physical roughness and chemical composition were changed. As a result, it was possible to observe a change in the mineral component of the particular dissolved in the solution and it was able to observe the characteristic changes of the parameters of the roughness of the lines and surfaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29280508','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29280508"><span>Does <span class="hlt">freeze</span>-all policy affect IVF outcomes in poor responders?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Roque, Matheus; Valle, Marcello; Sampaio, Marcos; Geber, Selmo</p> <p>2017-12-27</p> <p>To evaluate whether the <span class="hlt">freeze</span>-all strategy affects in vitro fertilization (IVF) outcomes in poor ovarian responders following the Bologna criteria. We performed a retrospective cohort study conducted between January 2012 and December 2016. A total of 433 poor responders (per the Bologna criteria) fulfilled the inclusion/exclusion criteria and were included in the study, with 277 patients included in the fresh group and 156 in the <span class="hlt">freeze</span>-all group. All patients were submitted to controlled ovarian stimulation (COS) with a gonadotropin-releasing hormone antagonist protocol and cleavage-stage embryo transfer (ET). The main outcome measure was ongoing pregnancy rate. Secondary outcomes included implantation and clinical pregnancy rates. The <span class="hlt">freeze</span>-all strategy was implemented when the progesterone serum level was >1.5 ng/mL on the trigger day, when the endometrium was <7 mm on the trigger day, or as a patient preference. Patients with previous failed fresh embryo transfer were also submitted to fresh or <span class="hlt">freeze</span>-all strategy considering the indications mentioned above. The patients' mean age in the <span class="hlt">freeze</span>-all group was 39.5±3.6 years, while that of patients in the fresh group was 39.7±3.8 years (P=0.54). The mean number of embryos transferred (nET) was 1.53±0.6 and 1.60±0.6 (P=0.12) in the <span class="hlt">freeze</span>-all and fresh groups, respectively. Ongoing pregnancy rates did not significantly differ between the <span class="hlt">freeze</span>-all and fresh groups (9.6% versus 10.1%, respectively; Relative Risk [RR]: 0.95; 95% CI: 0.52-1.73), nor did the clinical pregnancy rates (14.1% versus 13.7%, respectively; RR: 1.03; 95% CI: 0.63-1.76). Implantation rates were 9.6% and 9.8% (P=0.82) in the <span class="hlt">freeze</span>-all and fresh groups, respectively. The logistic regression analysis (including age, antral follicle count [AFC], the number of retrieved oocytes, the number of mature oocytes, nET, and fresh versus <span class="hlt">freeze</span>-all strategy) indicated that age (P<0.001) and the nET (P=0.039) were the only independent variables</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011TRACE..11..247H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011TRACE..11..247H"><span>Breeding of <span class="hlt">Freeze</span>-tolerant Yeast and the Mechanisms of Stress-tolerance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hino, Akihiro</p> <p></p> <p>Frozen dough method have been adopted in the baking industry to reduce labor and to produce fresh breads in stores. New <span class="hlt">freeze</span>-tolerant yeasts for frozen dough preparations were isolated from banana peel and identified. To obtain strains that have fermentative ability even after several months of frozen storage in fermented dough, we attempted to breed new <span class="hlt">freeze</span>-tolerantstrain. The hybrid between S.cerevisiae, which is a isolated <span class="hlt">freeze</span>-tolerant strain, and a strain isolated from bakers' yeast with sexual conjugation gave a good quality bread made from frozen dough method. <span class="hlt">Freeze</span>-tolerant strains showed higher surviving and trehalose accumulating abilities than <span class="hlt">freeze</span>-sensitive strains. The <span class="hlt">freeze</span> tolerance of the yeasts was associated with the basal amount of intracellular trehalose after rapid degradation at the onset of the prefermentation period. The complicated metabolic pathway and the regulation system of trehalose in yeast cells are introduced. The trehalose synthesis may act as a metabolic buffer system which contribute to maintain the intracellular inorganic phosphate and as a feedback regulation system in the glycolysis. However, it is not known enough how the trehalose protects yeast cells from stress.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.1615A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.1615A"><span>A coupled melt-<span class="hlt">freeze</span> temperature index approach in a one-layer model to predict bulk volumetric liquid water content dynamics in snow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Avanzi, Francesco; Yamaguchi, Satoru; Hirashima, Hiroyuki; De Michele, Carlo</p> <p>2016-04-01</p> <p>Liquid water in snow rules runoff dynamics and wet snow avalanches release. Moreover, it affects snow viscosity and snow albedo. As a result, measuring and modeling liquid water dynamics in snow have important implications for many scientific applications. However, measurements are usually challenging, while modeling is difficult due to an overlap of mechanical, thermal and hydraulic processes. Here, we evaluate the use of a simple one-layer one-dimensional model to predict hourly time-series of bulk volumetric liquid water content in seasonal snow. The model considers both a simple temperature-index approach (melt only) and a coupled melt-<span class="hlt">freeze</span> temperature-index approach that is able to reconstruct melt-<span class="hlt">freeze</span> dynamics. Performance of this approach is evaluated at three sites in Japan. These sites (Nagaoka, Shinjo and Sapporo) present multi-year time-series of snow and meteorological data, <span class="hlt">vertical</span> profiles of snow physical properties and snow melt lysimeters data. These data-sets are an interesting opportunity to test this application in different climatic conditions, as sites span a wide latitudinal range and are subjected to different snow conditions during the season. When melt-<span class="hlt">freeze</span> dynamics are included in the model, results show that median absolute differences between observations and predictions of bulk volumetric liquid water content are consistently lower than 1 vol%. Moreover, the model is able to predict an observed dry condition of the snowpack in 80% of observed cases at a non-calibration site, where parameters from calibration sites are transferred. Overall, the analysis show that a coupled melt-<span class="hlt">freeze</span> temperature-index approach may be a valid solution to predict average wetness conditions of a snow cover at local scale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27330265','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27330265"><span>Visual Indicators on Vaccine Boxes as Early Warning Tools to Identify Potential <span class="hlt">Freeze</span> Damage.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Angoff, Ronald; Wood, Jillian; Chernock, Maria C; Tipping, Diane</p> <p>2015-07-01</p> <p>The aim of this study was to determine whether the use of visual <span class="hlt">freeze</span> indicators on vaccines would assist health care providers in identifying vaccines that may have been exposed to potentially damaging temperatures. Twenty-seven sites in Connecticut involved in the Vaccine for Children Program participated. In addition to standard procedures, visual <span class="hlt">freeze</span> indicators (FREEZEmarker ® L; Temptime Corporation, Morris Plains, NJ) were affixed to each box of vaccine that required refrigeration but must not be frozen. Temperatures were monitored twice daily. During the 24 weeks, all 27 sites experienced triggered visual <span class="hlt">freeze</span> indicator events in 40 of the 45 refrigerators. A total of 66 triggered <span class="hlt">freeze</span> indicator events occurred in all 4 types of refrigerators used. Only 1 of the <span class="hlt">freeze</span> events was identified by a temperature-monitoring device. Temperatures recorded on vaccine data logs before <span class="hlt">freeze</span> indicator events were within the 35°F to 46°F (2°C to 8°C) range in all but 1 instance. A total of 46,954 doses of <span class="hlt">freeze</span>-sensitive vaccine were stored at the time of a visual <span class="hlt">freeze</span> indicator event. Triggered visual <span class="hlt">freeze</span> indicators were found on boxes containing 6566 doses (14.0% of total doses). Of all doses stored, 14,323 doses (30.5%) were of highly <span class="hlt">freeze</span>-sensitive vaccine; 1789 of these doses (12.5%) had triggered indicators on the boxes. Visual <span class="hlt">freeze</span> indicators are useful in the early identification of <span class="hlt">freeze</span> events involving vaccines. Consideration should be given to including these devices as a component of the temperature-monitoring system for vaccines.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.A23J3373B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.A23J3373B"><span>Observations of a stratospheric depletion and annual mean interhemispheric <span class="hlt">gradient</span> in the atmospheric Ar/N2 ratio from the HIPPO Global campaign</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bent, J. D.; Keeling, R. F.; Stephens, B. B.; Wofsy, S. C.; Daube, B. C.; Kort, E. A.; Pittman, J. V.; Jimenez-Pizarro, R.; Santoni, G.</p> <p>2014-12-01</p> <p>The atmospheric Ar/N2 ratio varies on a seasonal basis due to temperature-dependent solubility changes in the surface ocean. Low signal:noise ratios, limited <span class="hlt">vertical</span> coverage, and sampler-sampler offsets have historically hampered characterization of <span class="hlt">vertical</span> and inter-hemispheric <span class="hlt">gradients</span>. We present data from the HIPPO Global campaign (2009-11) showing that Ar/N2 and interannually-detrended N2O correlate well in the lower stratosphere, suggesting that, as stratospheric air ages and loses N2O to photolysis and photo-oxidation, it also gradually loses argon to gravity as the heavier atom preferentially "rains out" of the air parcel. The HIPPO Ar/N2 data from the lower troposphere also resolve seasonal cycles in each hemisphere, as well as a <span class="hlt">gradient</span> in the annual mean between hemispheres, with higher values in the southern hemisphere. The HIPPO cycles and inter-hemispheric <span class="hlt">gradient</span> are in good agreement with data from surface stations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AIPC..711..232M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AIPC..711..232M"><span>An Investigation of the Cryogenic <span class="hlt">Freezing</span> of Water in Non-Metallic Pipelines</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martin, C. I.; Richardson, R. N.; Bowen, R. J.</p> <p>2004-06-01</p> <p>Pipe <span class="hlt">freezing</span> is increasingly used in a range of industries to solve otherwise intractable pipe line maintenance and servicing problems. This paper presents the interim results from an experimental study on deliberate <span class="hlt">freezing</span> of polymeric pipelines. Previous and contemporary works are reviewed. The object of the current research is to confirm the feasibility of ice plug formation within a polymeric pipe as a method of isolation. Tests have been conducted on a range of polymeric pipes of various sizes. The results reported here all relate to <span class="hlt">freezing</span> of horizontal pipelines. In each case the process of plug formation was photographed, the frozen plug pressure tested and the pipe inspected for signs of damage resulting from the <span class="hlt">freeze</span> procedure. The time to <span class="hlt">freeze</span> was recorded and various temperatures logged. These tests have demonstrated that despite the poor thermal and mechanical properties of the polymers, <span class="hlt">freezing</span> offers a viable alternative method of isolation in polymeric pipelines.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24746509','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24746509"><span>Ultrasound assisted immersion <span class="hlt">freezing</span> of broccoli (Brassica oleracea L. var. botrytis L.).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xin, Ying; Zhang, Min; Adhikari, Benu</p> <p>2014-09-01</p> <p>The aim of this study was to research the ultrasound-assisted <span class="hlt">freezing</span> (UAF) of broccoli. CaCl2 solution was used as <span class="hlt">freezing</span> medium. The comparative advantage of using UAF over normal <span class="hlt">freezing</span> on the <span class="hlt">freezing</span> time, cell-wall bound calcium to total calcium ratio, textural properties, color, drip loss and L-ascorbic acid contents was evaluated. The application of UAF at selected acoustic intensity with a range of 0.250-0.412 W/cm(2) decreased the <span class="hlt">freezing</span> time and the loss of cell-wall bound calcium content. Compared to normal <span class="hlt">freezing</span>, the values of textural properties, color, L-ascorbic acid content were better preserved and the drip loss was significantly minimized by the application of UAF. However, when outside that range of acoustic intensity, the quality of the ultrasound-assisted frozen broccoli was inferior compared to that of the normally frozen samples. Selected the appropriate acoustic intensity was very important for the application of UAF. Copyright © 2014 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=202149','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=202149"><span>Survival differences among <span class="hlt">freeze</span>-dried genetically engineered and wild-type bacteria.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Israeli, E; Shaffer, B T; Hoyt, J A; Lighthart, B; Ganio, L M</p> <p>1993-01-01</p> <p>Because the death mechanisms of <span class="hlt">freeze</span>-dried and air-dried bacteria are thought to be similar, <span class="hlt">freeze</span>-drying was used to investigate the survival differences between potentially airborne genetically engineered microorganisms and their wild types. To this end, engineered strains of Escherichia coli and Pseudomonas syringae were <span class="hlt">freeze</span>-dried and exposed to air, visible light, or both. The death rates of all engineered strains were significantly higher than those of their parental strains. Light and air exposure were found to increase the death rates of all strains. Application of death rate models to <span class="hlt">freeze</span>-dried engineered bacteria to be released into the environment is discussed. PMID:8434925</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19940007570&hterms=planetary+motion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dplanetary%2Bmotion','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19940007570&hterms=planetary+motion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dplanetary%2Bmotion"><span>Horizontal stresses induced by <span class="hlt">vertical</span> processes in planetary lithospheres</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Banerdt, W. B.</p> <p>1993-01-01</p> <p>Understanding the state of stress in the elastic lithosphere is of fundamental importance for planetary geophysics, as it is the link between the observed geologic structures on the surface and the processes which form and modify these structures. As such, it can provide valuable constraints for the difficult problem of determining interior structure and processes. On the Earth, most large scale, organized deformation can be related to lateral tectonics associated with plate dynamics; however, the tectonics on many extraterrestrial bodies (such as the Moon, Mars, and most of the outer-planet satellites) appears to be primarily <span class="hlt">vertical</span> in nature, and the horizontal stresses induced by <span class="hlt">vertical</span> motions and loads are expected to dominate the deformation of their lithospheres. The largest stress contributions from <span class="hlt">vertical</span> loading come from the flexure of the lithosphere, which induces both bending moments and membrane stresses. We are concerned here only with nonflexural changes in the state of stress induced by processes such as sedimentary and volcanic deposition, erosional denudation, and changes in the thermal <span class="hlt">gradient</span> that induce uplift or subsidence. This analysis is important both for evaluating stresses for specific regions in which the <span class="hlt">vertical</span> stress history can be estimated, as well as for applying the proper loading conditions to global stress models. It is also of interest for providing a reference state of stress for interpreting stress measurements in the crust of the Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MNRAS.476.5115R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MNRAS.476.5115R"><span>Spiral density waves and <span class="hlt">vertical</span> circulation in protoplanetary discs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Riols, A.; Latter, H.</p> <p>2018-06-01</p> <p>Spiral density waves dominate several facets of accretion disc dynamics - planet-disc interactions and gravitational instability (GI) most prominently. Though they have been examined thoroughly in two-dimensional simulations, their <span class="hlt">vertical</span> structures in the non-linear regime are somewhat unexplored. This neglect is unwarranted given that any strong <span class="hlt">vertical</span> motions associated with these waves could profoundly impact dust dynamics, dust sedimentation, planet formation, and the emissivity of the disc surface. In this paper, we combine linear calculations and shearing box simulations in order to investigate the <span class="hlt">vertical</span> structure of spiral waves for various polytropic stratifications and wave amplitudes. For sub-adiabatic profiles, we find that spiral waves develop a pair of counter-rotating poloidal rolls. Particularly strong in the non-linear regime, these vortical structures issue from the baroclinicity supported by the background <span class="hlt">vertical</span> entropy <span class="hlt">gradient</span>. They are also intimately connected to the disc's g modes which appear to interact non-linearly with the density waves. Furthermore, we demonstrate that the poloidal rolls are ubiquitous in gravitoturbulence, emerging in the vicinity of GI spiral wakes, and potentially transporting grains off the disc mid-plane. Other than hindering sedimentation and planet formation, this phenomena may bear on observations of the disc's scattered infrared luminosity. The vortical features could also impact on the turbulent dynamo operating in young protoplanetary discs subject to GI, or possibly even galactic discs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26381808','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26381808"><span>Cognitive Contributions to <span class="hlt">Freezing</span> of Gait in Parkinson Disease: Implications for Physical Rehabilitation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Peterson, Daniel S; King, Laurie A; Cohen, Rajal G; Horak, Fay B</p> <p>2016-05-01</p> <p>People with Parkinson disease (PD) who show <span class="hlt">freezing</span> of gait also have dysfunction in cognitive domains that interact with mobility. Specifically, <span class="hlt">freezing</span> of gait is associated with executive dysfunction involving response inhibition, divided attention or switching attention, and visuospatial function. The neural control impairments leading to <span class="hlt">freezing</span> of gait have recently been attributed to higher-level, executive and attentional cortical processes involved in coordinating posture and gait rather than to lower-level, sensorimotor impairments. To date, rehabilitation for <span class="hlt">freezing</span> of gait primarily has focused on compensatory mobility training to overcome <span class="hlt">freezing</span> events, such as sensory cueing and voluntary step planning. Recently, a few interventions have focused on restitutive, rather than compensatory, therapy. Given the documented impairments in executive function specific to patients with PD who <span class="hlt">freeze</span> and increasing evidence of overlap between cognitive and motor function, incorporating cognitive challenges with mobility training may have important benefits for patients with <span class="hlt">freezing</span> of gait. Thus, a novel theoretical framework is proposed for exercise interventions that jointly address both the specific cognitive and mobility challenges of people with PD who <span class="hlt">freeze</span>. © 2016 American Physical Therapy Association.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28042668','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28042668"><span>Leaf water 18 O and 2 H enrichment along <span class="hlt">vertical</span> canopy profiles in a broadleaved and a conifer forest tree.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bögelein, Rebekka; Thomas, Frank M; Kahmen, Ansgar</p> <p>2017-07-01</p> <p>Distinguishing meteorological and plant-mediated drivers of leaf water isotopic enrichment is prerequisite for ecological interpretations of stable hydrogen and oxygen isotopes in plant tissue. We measured input and leaf water δ 2 H and δ 18 O as well as micrometeorological and leaf morpho-physiological variables along a <span class="hlt">vertical</span> <span class="hlt">gradient</span> in a mature angiosperm (European beech) and gymnosperm (Douglas fir) tree. We used these variables and different enrichment models to quantify the influence of Péclet and non-steady state effects and of the biophysical drivers on leaf water enrichment. The two-pool model accurately described the diurnal variation of leaf water enrichment. The estimated unenriched water fraction was linked to leaf dry matter content across the canopy heights. Non-steady state effects and reduced stomatal conductance caused a higher enrichment of Douglas fir compared to beech leaf water. A dynamic effect analyses revealed that the light-induced <span class="hlt">vertical</span> <span class="hlt">gradients</span> of stomatal conductance and leaf temperature outbalanced each other in their effects on evaporative enrichment. We conclude that neither <span class="hlt">vertical</span> canopy <span class="hlt">gradients</span> nor the Péclet effect is important for estimates and interpretation of isotopic leaf water enrichment in hypostomatous trees. Contrarily, species-specific non-steady state effects and leaf temperatures as well as the water vapour isotope composition need careful consideration. © 2017 John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRD..123..882W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRD..123..882W"><span>Generalized Dynamic Equations Related to Condensation and <span class="hlt">Freezing</span> Processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Xingrong; Huang, Yong</p> <p>2018-01-01</p> <p>The generalized thermodynamic equation related to condensation and <span class="hlt">freezing</span> processes was derived by introducing the condensation and <span class="hlt">freezing</span> probability function into the dynamic framework based on the statistical thermodynamic fluctuation theory. As a result, the physical mechanism of some weather phenomena covered by using <fi>δ</fi>(0,1) can in turn be studied and uncovered. From the generalized dynamic equations, the tendency equation of the generalized potential vorticity (GPV) is derived. From the discussion of tendency equation of GPV, in some very thin transitional areas, GPV is found nonconserved because of the introduction of the condensation and <span class="hlt">freezing</span> probability function, even in frictionless and moist adiabatic air motion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29600616','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29600616"><span>[<span class="hlt">Freeze</span> drying process optimization of ginger juice-adjuvant for Chinese materia medica processing and stability of <span class="hlt">freeze</span>-dried ginger juice powder].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, Chun-Yu; Guo, Feng-Qian; Zang, Chen; Cao, Hui; Zhang, Bao-Xian</p> <p>2018-02-01</p> <p>Ginger juice, a commonly used adjuvant for Chinese materia medica, is applied in processing of multiple Chinese herbal decoction pieces. Because of the raw materials and preparation process of ginger juice, it is difficult to be preserved for a long time, and the dosage of ginger juice in the processing can not be determined base on its content of main compositions. Ginger juice from different sources is hard to achieve consistent effect during the processing of traditional Chinese herbal decoction pieces. Based on the previous studies, the <span class="hlt">freeze</span> drying of ginger juice under different shelf temperatures and vacuum degrees were studied, and the optimized <span class="hlt">freeze</span> drying condition of ginger juice was determined. The content determination method for 6-gingerol, 8-gingerol, 10-gingerol and 6-shagaol in ginger juice and redissolved ginger juice was established. The content changes of 6-gingerol, 8-gingerol, 10-gingerol, 6-gingerol, 6-shagaol, volatile oil and total phenol were studied through the drying process and 30 days preservation period. The results showed that the <span class="hlt">freeze</span> drying time of ginger juice was shortened after process optimization; the compositions basically remained unchanged after <span class="hlt">freeze</span> drying, and there was no significant changes in the total phenol content and gingerol content, but the volatile oil content was significantly decreased( P <0.05). Within 30 days, the contents of gingerol, total phenol, and volatile oil were on the decline as a whole. This study has preliminarily proved the feasibility of <span class="hlt">freeze</span>-drying process of ginger juice as an adjuvant for Chinese medicine processing. Copyright© by the Chinese Pharmaceutical Association.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSA43A2130K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSA43A2130K"><span>Estimation of mesospheric <span class="hlt">vertical</span> winds from a VHF meteor radar at King Sejong Station, Antarctica (62.2S, 58.8W)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Y.; Lee, C.; Kim, J.; Jee, G.</p> <p>2013-12-01</p> <p>For the first time, <span class="hlt">vertical</span> winds near the mesopause region were estimated from radial velocities of meteor echoes detected by a VHF meteor radar at King Sejong Station (KSS) in 2011 and 2012. Since the radar usually detects more than a hundred echoes every hour in an altitude bin of 88 - 92 km, much larger than other radars, we were able to fit measured radial velocities of these echoes with a 6 component model that consists of horizontal winds, spatial <span class="hlt">gradients</span> of horizontal winds and <span class="hlt">vertical</span> wind. The conventional method of deriving horizontal winds from meteor echoes utilizes a 2 component model, assuming that <span class="hlt">vertical</span> winds and spatial <span class="hlt">gradients</span> of horizontal winds are negligible. We analyzed the radar data obtained for 8400 hours in 2012 and 8100 hours in 2011. We found that daily mean values of <span class="hlt">vertical</span> winds are mostly within +/- 1 m/s, whereas those of zonal winds are a few tens m/s mostly eastward. The daily mean <span class="hlt">vertical</span> winds sometimes stay positive or negative for more than 20 days, implying that the atmosphere near the mesopause experiences episodically a large scale low and high pressure environments, respectively, like the tropospheric weather system. By conducting Lomb-normalized periodogram analysis, we also found that the <span class="hlt">vertical</span> winds have diurnal, semidiurnal and terdiurnal tidal components with about equal significance, in contrast to horizontal winds that show a dominant semidiurnal one. We will discuss about uncertainties of the estimated <span class="hlt">vertical</span> wind and possible reasons of its tidal and daily variations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3586257','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3586257"><span>Thermomechanical analysis of <span class="hlt">freezing</span>-induced cell-fluid-matrix interactions in engineered tissues</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Han, Bumsoo; Teo, Ka Yaw; Ghosh, Soham; Dutton, J. Craig; Grinnell, Frederick</p> <p>2012-01-01</p> <p>Successful cryopreservation of functional engineered tissues (ETs) is significant to tissue engineering and regenerative medicine, but it is extremely challenging to develop a successful protocol because the effects of cryopreservation parameters on the post-thaw functionality of ETs are not well understood. Particularly, the effects on the microstructure of their extracellular matrix (ECM) have not been well studied, which determines many functional properties of the ETs. In this study, we investigated the effects of two key cryopreservation parameters – i) <span class="hlt">freezing</span> temperature and corresponding cooling rate; and ii) the concentration of cryoprotective agent (CPA) on the ECM microstructure as well as the cellular viability. Using dermal equivalent as a model ET and DMSO as a model CPA, <span class="hlt">freezing</span>-induced spatiotemporal deformation and post-thaw ECM microstructure of ETs was characterized while varying the <span class="hlt">freezing</span> temperature and DMSO concentrations. The spatial distribution of cellular viability and the cellular actin cytoskeleton was also examined. The results showed that the tissue dilatation increased significantly with reduced <span class="hlt">freezing</span> temperature (i.e., rapid <span class="hlt">freezing</span>). A maximum limit of tissue deformation was observed for preservation of ECM microstructure, cell viability and cell-matrix adhesion. The dilatation decreased with the use of DMSO, and a <span class="hlt">freezing</span> temperature dependent threshold concentration of DMSO was observed. The threshold DMSO concentration increased with lowering <span class="hlt">freezing</span> temperature. In addition, an analysis was performed to delineate thermodynamic and mechanical components of <span class="hlt">freezing</span>-induced tissue deformation. The results are discussed to establish a mechanistic understanding of <span class="hlt">freezing</span>-induced cell-fluid-matrix interaction and phase change behavior within ETs in order to improve cryopreservation of ETs. PMID:23246556</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28447204','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28447204"><span>Comparative transcriptome profiling of <span class="hlt">freezing</span> stress responses in loquat (Eriobotrya japonica) fruitlets.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xu, Hong-Xia; Li, Xiao-Ying; Chen, Jun-Wei</p> <p>2017-09-01</p> <p>Loquat (Eriobotrya japonica Lindl.) is an important subtropical, commercial fruit in China. It blossoms during autumn and winter in most areas of China and its fruitlets usually suffer from <span class="hlt">freezing</span> stress. However, studies about the mechanisms underlying <span class="hlt">freezing</span> stress in loquat are very limited. The gene expression profiles of loquat fruitlets subjected to <span class="hlt">freezing</span> (G2 library) versus non-treated ones (G1 library) were investigated using Illumina sequencing technology to elucidate the molecular mechanisms and identify the genes that play vital roles in the <span class="hlt">freezing</span> stress response. The results showed that approximately 157.63 million reads in total were obtained from <span class="hlt">freeze</span>-treated and non-treated loquat fruitlets. These reads were assembled into 87,379 unigenes with an average length of 710 bp and an N50 of 1,200 bp. After comparing the profiles obtained from the G1 and G2 libraries, 2,892 differentially expressed genes were identified, of which 1,883 were up-regulated and 1,009 were down-regulated in the treated samples compared to non-treated ones. These unigenes showed significant differences in expression for carbohydrate transport and metabolism, amino acid metabolism, energy metabolism, and lipid metabolism, which are involved in defense against <span class="hlt">freezing</span> stress. Glycolysis/gluconeogenesis was one of the most significantly regulated pathways. <span class="hlt">Freezing</span> also significantly damaged the membrane system of loquat fruitlets, and several defense mechanisms were induced. Some selected genes related to low temperature resistance were validated by quantitative real-time PCR (qRT-PCR). The results revealed many genes and pathways that are part of <span class="hlt">freezing</span> resistance processes and expand our understanding of the complex molecular events involved in <span class="hlt">freezing</span> stress.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27094858','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27094858"><span>Handwriting Impairments in People With Parkinson's Disease and <span class="hlt">Freezing</span> of Gait.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Heremans, Elke; Nackaerts, Evelien; Broeder, Sanne; Vervoort, Griet; Swinnen, Stephan P; Nieuwboer, Alice</p> <p>2016-11-01</p> <p>Recent studies show that patients with Parkinson's disease (PD) and <span class="hlt">freezing</span> of gait (FOG) experience motor problems outside their gait <span class="hlt">freezing</span> episodes. Because handwriting is also a sequential movement, it may be affected in PD patients with FOG relative to those without. The current study aimed to assess the quality of writing in PD patients with and without FOG in comparison to healthy controls (CTs) during various writing tasks. Handwriting was assessed by the writing of cursive loops on a touch-sensitive writing tablet and by means of the Systematic Screening of Handwriting Difficulties (SOS) test in 30 PD patients with and without <span class="hlt">freezing</span> and 15 healthy age-matched CTs. The tablet tests were performed at 2 different sizes, either continuously or alternatingly, as indicated by visual target lines. Patients with <span class="hlt">freezing</span> showed decreased writing amplitudes and increased variability compared with CTs and patients without <span class="hlt">freezing</span> on the writing tablet tests. Writing problems were present during both tests but were more pronounced during writing at alternating compared with writing at continuous size. Patients with <span class="hlt">freezing</span> also had a higher total score on the SOS test than patients without <span class="hlt">freezing</span> and CTs, reflecting more extensive handwriting problems, particularly with writing fluency. Writing is more severely affected in PD patients with FOG than in those without FOG. These results indicate that deficient movement sequencing and adaptation is a generic problem in patients with FOG. © The Author(s) 2016.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28758815','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28758815"><span>Physicochemical interaction mechanism between nanoparticles and tetrasaccharides (stachyose) during <span class="hlt">freeze</span>-drying.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kamiya, Seitaro; Nakashima, Kenichiro</p> <p>2017-12-01</p> <p>Nanoparticle suspensions are thermodynamically unstable and subject to aggregation. <span class="hlt">Freeze</span>-drying on addition of saccharides is a useful method for preventing aggregation. In the present study, tetrasaccharides (stachyose) was employed as an additive. In addition, we hypothesize the interactive mechanism between stachyose and the nanoparticles during <span class="hlt">freeze</span>-drying for the first time. The mean particle size of the rehydrated <span class="hlt">freeze</span>-dried stachyose-containing nanoparticles (104.7 nm) was similar to the initial particle size before <span class="hlt">freeze</span>-drying (76.8 nm), indicating that the particle size had been maintained. The mean particle size of the rehydrated normal-dried stachyose-containing nanoparticles was 222.2 nm. The powder X-ray diffraction of the <span class="hlt">freeze</span>-dried stachyose-containing nanoparticles revealed a halo pattern. The powder X-ray diffraction of the normally dried stachyose-containing nanoparticles produced mainly a halo pattern and a partial peak. These results suggest an interaction between the nanoparticles and stachyose, and that this relationship depends on whether the mixture is <span class="hlt">freeze</span>-dried or dried normally. In the case of normal drying, although most molecules cannot move rapidly thereby settling irregularly, some stachyose molecules can arrange regularly leading to some degree of crystallization and potentially some aggregation. In contrast, during <span class="hlt">freeze</span>-drying, the moisture sublimed, while the stachyose molecules and nanoparticles were immobilized in the ice. After sublimation, stachyose remained in the space occupied by water and played the role of a buffer material, thus preventing aggregation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29905948','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29905948"><span>Migration of Water in Litopenaeus Vannamei Muscle Following <span class="hlt">Freezing</span> and Thawing.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Deng, Qi; Wang, Yaling; Sun, Lijun; Li, Jianrong; Fang, Zhijia; Gooneratne, Ravi</p> <p>2018-06-15</p> <p>Water and protein are major constituents of shrimp, any changes in protein and the state of water influence the quality of shrimp. Therefore, a study to examine the law of moisture migration and protein denaturation under different <span class="hlt">freezing</span> and thawing conditions is important. The proton density images of thawed frozen-shrimp revealed that the water loss during quick-<span class="hlt">freezing</span> was much greater than that during slow <span class="hlt">freezing</span> or microfreezing. At room temperature (25 °C), the water loss from brine-thawing was more than still-water thawing and still-water thawing was more than thawing spontaneously. <span class="hlt">Freezing</span>-thawing resulted in uniform water redistribution in shrimp muscle. Nuclear magnetic resonance technology (low field magnetic imaging) was used to directly monitor the dynamic processes of fluidity state in shrimp and indirectly monitor protein denaturation and thereby determine the optimal method of <span class="hlt">freezing</span>-thawing shrimp. Our research showed that microfreezing preservation minimized weight loss, juice leakage and protein denaturation in shrimp muscle during thawing. Water is one of the major components in most organs and is an important factor that influences the shrimp muscle quality. Water migration patterns and subsequent effects on the shrimp muscle under different <span class="hlt">freezing</span> and thawing conditions were examined using low field nuclear magnetic resonance (NMR) technology. This research provides a theoretical foundation for shrimp processing plants to improve the <span class="hlt">freezing</span> and thawing process to obtain optimal quality and flavor of shrimp products. © 2018 Institute of Food Technologists®.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AtmEn..43.5526Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AtmEn..43.5526Z"><span><span class="hlt">Vertical</span> distributions of aerosols under different weather conditions: Analysis of in-situ aircraft measurements in Beijing, China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Qiang; Ma, XinCheng; Tie, Xuexi; Huang, Mengyu; Zhao, Chunsheng</p> <p></p> <p>In this study, aerosol <span class="hlt">vertical</span> distributions of 17 in-situ aircraft measurements during 2005 and 2006 springs are analyzed. The 17 flights are carefully selected to exclude dust events, and the analyses are focused on the <span class="hlt">vertical</span> distributions of aerosol particles associated with anthropogenic activities. The results show that the <span class="hlt">vertical</span> distributions of aerosol particles are strongly affected by weather and meteorological conditions, and 3 different types of aerosol <span class="hlt">vertical</span> distributions corresponding to different weather systems are defined in this study. The measurement with a flat <span class="hlt">vertical</span> <span class="hlt">gradient</span> and low surface aerosol concentrations is defined as type-1; a gradual decrease of aerosols with altitudes and modest surface aerosol concentrations is defined as type-2; a sharp <span class="hlt">vertical</span> <span class="hlt">gradient</span> (aerosols being strongly depressed in the PBL) with high surface aerosol concentrations is defined as type-3. The weather conditions corresponding to the 3 different aerosol types are high pressure, between two high pressures, and low pressure systems (frontal inversions), respectively. The <span class="hlt">vertical</span> mixing and horizontal transport for the 3 different <span class="hlt">vertical</span> distributions are analyzed. Under the type-1 condition, the <span class="hlt">vertical</span> mixing and horizontal transport were rapid, leading to strong dilution of aerosols in both <span class="hlt">vertical</span> and horizontal directions. As a result, the aerosol concentrations in PBL (planetary boundary layer) were very low, and the <span class="hlt">vertical</span> distribution was flat. Under the type-2 condition, the <span class="hlt">vertical</span> mixing was strong and there was no strong barrier at the PBL height. The horizontal transport (wind flux) was modest. As a result, the aerosol concentrations were gradually reduced with altitude, with modest surface aerosol concentrations. Under the type-3 condition, there was a cold front near the region. As a result, a frontal inversion associated with weak <span class="hlt">vertical</span> mixing appeared at the top of the inversion layer, forming a very strong barrier to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AdWR..111..319A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AdWR..111..319A"><span>A theoretical extension of the soil <span class="hlt">freezing</span> curve paradigm</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Amiri, Erfan A.; Craig, James R.; Kurylyk, Barret L.</p> <p>2018-01-01</p> <p>Numerical models of permafrost evolution in porous media typically rely upon a smooth continuous relation between pore ice saturation and sub-<span class="hlt">freezing</span> temperature, rather than the abrupt phase change that occurs in pure media. Soil scientists have known for decades that this function, known as the soil <span class="hlt">freezing</span> curve (SFC), is related to the soil water characteristic curve (SWCC) for unfrozen soils due to the analogous capillary and sorptive effects experienced during both soil <span class="hlt">freezing</span> and drying. Herein we demonstrate that other factors beyond the SFC-SWCC relationship can influence the potential range over which pore water phase change occurs. In particular, we provide a theoretical extension for the functional form of the SFC based upon the presence of spatial heterogeneity in both soil thermal conductivity and the <span class="hlt">freezing</span> point depression of water. We infer the functional form of the SFC from many abrupt-interface 1-D numerical simulations of heterogeneous systems with prescribed statistical distributions of water and soil properties. The proposed SFC paradigm extension has the appealing features that it (1) is determinable from measurable soil and water properties, (2) collapses into an abrupt phase transition for homogeneous media, (3) describes a wide range of heterogeneity within a single functional expression, and (4) replicates the observed hysteretic behavior of <span class="hlt">freeze</span>-thaw cycles in soils.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/1030437','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/1030437"><span>The physico-chemical basis for the <span class="hlt">freeze</span>-drying process.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>MacKenzie, A P</p> <p>1976-10-01</p> <p>To the extent that the final form and quality of a <span class="hlt">freeze</span>-dried product depends on the way the <span class="hlt">freeze</span>-drying is conducted, an understanding of the many factors involved is most important. The numerous effects of the design and mode of operation of the <span class="hlt">freeze</span>-drying equipment on the course of the process need to be known, as do the properties intrinsic to the material to be <span class="hlt">freeze</span>-dried. Much can be learned and predicted from the study of the "supplemented phase diagram", a series of experimental plots describing the equilibrium and the non-equilibrium phase behavior of the system in question. Such diagrams map and distinguish eutectic and amorphous phase behavior. Further information is available from gravimetric studies allowing the construction of "desorption isotherms", the plots describing the loss of sorbed water accompanying the sublimation of ice, frequently termed "secondary drying". These plots relate the water retained by the product to the "water activity", or relative humidity at different temperatures. Observations in the <span class="hlt">freeze</span>-drying microscope contribute additional information, in that they reveal the actual course of the process at the microscopic level. These and other laboratory findings facilitate the analysis and comparison of pilot-plant and commercical scale processing experiences. Where scientific and engineering factors appear to interrelate, the nature and extent of the interdependence can often be determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A53A2204B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A53A2204B"><span>Utilizing NASA DISCOVER-AQ Data to Examine Spatial <span class="hlt">Gradients</span> in Complex Emission Environments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Buzanowicz, M. E.; Moore, W.; Crawford, J. H.; Schroeder, J.</p> <p>2017-12-01</p> <p>Although many regulations have been enacted with the goal of improving air quality, many parts of the US are still classified as `non-attainment areas' because they frequently violate federal air quality standards. Adequately monitoring the spatial distribution of pollutants both within and outside of non-attainment areas has been an ongoing challenge for regulators. Observations of near-surface pollution from space-based platforms would provide an unprecedented view of the spatial distribution of pollution, but this goal has not yet been realized due to fundamental limitations of satellites, specifically because the footprint size of satellite measurements may not be sufficiently small enough to capture true <span class="hlt">gradients</span> in pollution, and rather represents an average over a large area. NASA's DISCOVER-AQ was a multi-year field campaign aimed at improving our understanding of the role that remote sensing, including satellite-based remote sensing, could play in air quality monitoring systems. DISCOVER-AQ data will be utilized to create a metric to examine spatial <span class="hlt">gradients</span> and how satellites can capture those <span class="hlt">gradients</span> in areas with complex emission environments. Examining horizontal variability within a <span class="hlt">vertical</span> column is critical to understanding mixing within the atmosphere. Aircraft spirals conducted during DISCOVER-AQ were divided into octants, and averages of a given a species were calculated, with certain points receiving a flag. These flags were determined by calculating <span class="hlt">gradients</span> between subsequent octants. Initial calculations have shown that over areas with large point source emissions, such as Platteville and Denver-La Casa in Colorado, and Essex, Maryland, satellite retrievals may not adequately capture spatial variability in the atmosphere, thus complicating satellite inversion techniques and limiting our ability to understand human exposure on sub-grid scales. Further calculations at other locations and for other trace gases are necessary to determine</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2788418','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2788418"><span>Synchrotron X-Ray Visualisation of Ice Formation in Insects during Lethal and Non-Lethal <span class="hlt">Freezing</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sinclair, Brent J.; Gibbs, Allen G.; Lee, Wah-Keat; Rajamohan, Arun; Roberts, Stephen P.; Socha, John J.</p> <p>2009-01-01</p> <p>Although the biochemical correlates of <span class="hlt">freeze</span> tolerance in insects are becoming well-known, the process of ice formation in vivo is subject to speculation. We used synchrotron x-rays to directly visualise real-time ice formation at 3.3 Hz in intact insects. We observed <span class="hlt">freezing</span> in diapausing 3rd instar larvae of Chymomyza amoena (Diptera: Drosophilidae), which survive <span class="hlt">freezing</span> if it occurs above −14°C, and non-diapausing 3rd instar larvae of C. amoena and Drosophila melanogaster (Diptera: Drosophilidae), neither of which survive <span class="hlt">freezing</span>. <span class="hlt">Freezing</span> was readily observed in all larvae, and on one occasion the gut was seen to <span class="hlt">freeze</span> separately from the haemocoel. There were no apparent qualitative differences in ice formation between <span class="hlt">freeze</span> tolerant and non-<span class="hlt">freeze</span> tolerant larvae. The time to complete <span class="hlt">freezing</span> was positively related to temperature of nucleation (supercooling point, SCP), and SCP declined with decreasing body size, although this relationship was less strong in diapausing C. amoena. Nucleation generally occurred at a contact point with the thermocouple or chamber wall in non-diapausing larvae, but at random in diapausing larvae, suggesting that the latter have some control over ice nucleation. There were no apparent differences between <span class="hlt">freeze</span> tolerant and non-<span class="hlt">freeze</span> tolerant larvae in tracheal displacement or distension of the body during <span class="hlt">freezing</span>, although there was markedly more distension in D. melanogaster than in C. amoena regardless of diapause state. We conclude that although control of ice nucleation appears to be important in <span class="hlt">freeze</span> tolerant individuals, the physical ice formation process itself does not differ among larvae that can and cannot survive <span class="hlt">freezing</span>. This suggests that a focus on cellular and biochemical mechanisms is appropriate and may reveal the primary adaptations allowing <span class="hlt">freeze</span> tolerance in insects. PMID:20011523</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11756272','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11756272"><span><span class="hlt">Freeze</span> Tolerance of Seed-Producing Turf Bermudagrasses.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Anderson, Jeffrey A.; Taliaferro, Charles M.</p> <p>2002-01-01</p> <p>Bermudagrass, Cynodon dactylon (L.) Pers., suffers periodic severe winter-kill throughout much of its area of use in the contiguous USA. A research goal is to increase <span class="hlt">freeze</span> tolerance in cultivars to lessen the risk of such damage. An identified research need is for Cynodon germplasm resources to be characterized for <span class="hlt">freeze</span> tolerance and hybridization potential. Accordingly, the objective of this research was to characterize the relative <span class="hlt">freeze</span> tolerance of selected fertile bermudagrass plants. Nine tetraploid (2n = 4x = 36) C. dactylon and two triploid (2n = 3x = 27) hybrid (C. dactylon x C. transvaalensis Burtt Davy) clonal plants (standards) were evaluated in two experiments. Plants were propagated clonally and established in Cone-tainers (Ray Leach Cone-tainer Nursery, Canby, OR) for about 10 wk. Acclimation took place for 4 wk in controlled environment chambers at 8/2 degrees C (day/night) temperatures with a 10-h photoperiod. Following acclimation, Cone-tainers were placed into a <span class="hlt">freeze</span> chamber and cooled rapidly to -2 degrees C, induced to <span class="hlt">freeze</span> with ice chips, then held overnight at -2 degrees C. The <span class="hlt">freeze</span> chamber was then programmed to cool linearly at 1 degrees C per hour. For each cultivar, three Cone-tainers were removed at each test temperature. Following thawing, Cone-tainers were transferred to a greenhouse and regrowth was evaluated visually. Nonlinear regression was used to estimate T(mid), which corresponded to the midpoint of the sigmoidal response curve of survival vs temperature. Within experiment one, Tifgreen (T(mid) = -7.2 degrees C) was significantly less cold hardy than Quickstand (-9.0 degrees C), A-12204 (-9.2 degrees C), Midiron (-9.9 degrees C), and A-12195 (-10.5 degrees C). A-12195 was significantly hardier than all genotypes except Midiron. In the second experiment, Arizona Common (-6.6 degrees C), Tifgreen (-7.1 degrees C), and A-12205 (-7.1 degrees C) were less hardy than A-9959 (-8.7 degrees C), A-12156 (-8.9 degrees C), A</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20680128','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20680128"><span>Validation of the shake test for detecting <span class="hlt">freeze</span> damage to adsorbed vaccines.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kartoglu, Umit; Ozgüler, Nejat Kenan; Wolfson, Lara J; Kurzatkowski, Wiesław</p> <p>2010-08-01</p> <p>To determine the validity of the shake test for detecting <span class="hlt">freeze</span> damage in aluminium-based, adsorbed, <span class="hlt">freeze</span>-sensitive vaccines. A double-blind crossover design was used to compare the performance of the shake test conducted by trained health-care workers (HCWs) with that of phase contrast microscopy as a "gold standard". A total of 475 vials of 8 different types of World Health Organization prequalified <span class="hlt">freeze</span>-sensitive vaccines from 10 different manufacturers were used. Vaccines were kept at 5 degrees C. Selected numbers of vials from each type were then exposed to -25 degrees C and -2 degrees C for 24-hour periods. There was complete concordance between HCWs and phase-contrast microscopy in identifying <span class="hlt">freeze</span>-damaged vials and non-frozen samples. Non-frozen samples showed a fine-grain structure under phase contrast microscopy, but <span class="hlt">freeze</span>-damaged samples showed large conglomerates of massed precipitates with amorphous, crystalline, solid and needle-like structures. Particles in the non-frozen samples measured from 1 microm (vaccines against diphtheria-tetanus-pertussis; Haemophilus influenzae type b; hepatitis B; diphtheria-tetanus-pertussis-hepatitis B) to 20 microm (diphtheria and tetanus vaccines, alone or in combination). By contrast, aggregates in the <span class="hlt">freeze</span>-damaged samples measured up to 700 microm (diphtheria-tetanus-pertussis) and 350 microm on average. The shake test had 100% sensitivity, 100% specificity and 100% positive predictive value in this study, which confirms its validity for detecting <span class="hlt">freeze</span> damage to aluminium-based <span class="hlt">freeze</span>-sensitive vaccines.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3135600','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3135600"><span>Experience Modulates Vicarious <span class="hlt">Freezing</span> in Rats: A Model for Empathy</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Atsak, Piray; Orre, Marie; Bakker, Petra; Cerliani, Leonardo; Roozendaal, Benno</p> <p>2011-01-01</p> <p>The study of the neural basis of emotional empathy has received a surge of interest in recent years but mostly employing human neuroimaging. A simpler animal model would pave the way for systematic single cell recordings and invasive manipulations of the brain regions implicated in empathy. Recent evidence has been put forward for the existence of empathy in rodents. In this study, we describe a potential model of empathy in female rats, in which we studied interactions between two rats: a witness observes a demonstrator experiencing a series of footshocks. By comparing the reaction of witnesses with or without previous footshock experience, we examine the role of prior experience as a modulator of empathy. We show that witnesses having previously experienced footshocks, but not naïve ones, display vicarious <span class="hlt">freezing</span> behavior upon witnessing a cage-mate experiencing footshocks. Strikingly, the demonstrator's behavior was in turn modulated by the behavior of the witness: demonstrators froze more following footshocks if their witness froze more. Previous experiments have shown that rats emit ultrasonic vocalizations (USVs) when receiving footshocks. Thus, the role of USV in triggering vicarious <span class="hlt">freezing</span> in our paradigm is examined. We found that experienced witness-demonstrator pairs emitted more USVs than naïve witness-demonstrator pairs, but the number of USVs was correlated with <span class="hlt">freezing</span> in demonstrators, not in witnesses. Furthermore, playing back the USVs, recorded from witness-demonstrator pairs during the empathy test, did not induce vicarious <span class="hlt">freezing</span> behavior in experienced witnesses. Thus, our findings confirm that vicarious <span class="hlt">freezing</span> can be triggered in rats, and moreover it can be modulated by prior experience. Additionally, our result suggests that vicarious <span class="hlt">freezing</span> is not triggered by USVs per se and it influences back onto the behavior of the demonstrator that had elicited the vicarious <span class="hlt">freezing</span> in witnesses, introducing a paradigm to study empathy</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28946071','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28946071"><span>Microplate <span class="hlt">freeze</span>-dried cyanobacterial bioassay for fresh-waters environmental monitoring.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Martín-Betancor, Keila; Durand, Marie-José; Thouand, Gérald; Leganés, Francisco; Fernández-Piñas, Francisca; Rodea-Palomares, Ismael</p> <p>2017-12-01</p> <p>Microorganisms have been very useful in environmental monitoring due to their constant sensing of the surrounding environment, their easy maintenance and low cost. Some <span class="hlt">freeze</span>-dried toxicity kits based on naturally bioluminescent bacteria are commercially available and commonly used to assess the toxicity of environmental samples such as Microtox (Aliivibrio fischeri) or ToxScreen (Photobacterium leiognathi), however, due to the marine origin of these bacteria, they could not be the most appropriate for fresh-waters monitoring. Cyanobacteria are one of the most representative microorganisms of aquatic environments, and are well suited for detecting contaminants in aqueous samples. This study presents the development and application of the first <span class="hlt">freeze</span>-dried cyanobacterial bioassay for fresh-water contaminants detection. The effects of different cell growth phases, cryoprotectant solutions, <span class="hlt">freezing</span> protocols, rehydration solutions and incubation conditions methods were evaluated and the best combination of these parameters for <span class="hlt">freeze</span>-drying was selected. The study includes detailed characterization of sensitivity towards reference pollutants, as well as, comparison with the standard assays. Moreover, long-term viability and sensitivity were evaluated after 3 years of storage. <span class="hlt">Freeze</span>-dried cyanobacteria showed, in general, higher sensitivity than the standard assays and viability of the cells remained after 3 years of storage. Finally, the validation of the bioassay using a wastewater sample was also evaluated. <span class="hlt">Freeze</span>-drying of cyanobacteria in 96-well plates presents a simple, fast and multi-assay method for environmental monitoring. Copyright © 2017 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008IJT....29....1L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008IJT....29....1L"><span>A Determination of the Ratio of the Zinc <span class="hlt">Freezing</span> Point to the Tin <span class="hlt">Freezing</span> Point by Noise Thermometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Labenski, J. R.; Tew, W. L.; Benz, S. P.; Nam, S. W.; Dresselhaus, P.</p> <p>2008-02-01</p> <p>A Johnson-noise thermometer (JNT) has been used with a quantized voltage noise source (QVNS), as a calculable reference to determine the ratio of temperatures near the Zn <span class="hlt">freezing</span> point to those near the Sn <span class="hlt">freezing</span> point. The temperatures are derived in a series of separate measurements comparing the synthesized noise power from the QVNS with that of Johnson noise from a known resistance. The synthesized noise power is digitally programed to match the thermal noise powers at both temperatures and provides the principle means of scaling the temperatures. This produces a relatively flat spectrum for the ratio of spectral noise densities, which is close to unity in the low-frequency limit. The data are analyzed as relative spectral ratios over the 4.8 to 450 kHz range averaged over a 3.2 kHz bandwidth. A three-parameter model is used to account for differences in time constants that are inherently temperature dependent. A drift effect of approximately -6 μK·K-1 per day is observed in the results, and an empirical correction is applied to yield a relative difference in temperature ratios of -11.5 ± 43 μK·K-1 with respect to the ratio of temperatures assigned on the International Temperature Scale of 1990 (ITS-90). When these noise thermometry results are combined with results from acoustic gas thermometry at temperatures near the Sn <span class="hlt">freezing</span> point, a value of T - T 90 = 7 ± 30 mK for the Zn <span class="hlt">freezing</span> point is derived.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4662152','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4662152"><span>Effect of Repeated <span class="hlt">Freeze</span>-Thaw Cycles on Beef Quality and Safety</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rahman, Mohammad Hafizur; Hossain, Mohammad Mujaffar; Rahman, Syed Mohammad Ehsanur; Hashem, Mohammad Abul</p> <p>2014-01-01</p> <p>The objectives of this study were to know the effect of repeated <span class="hlt">freeze</span>-thaw cycles of beef on the sensory, physicochemical quality and microbiological assessment. The effects of three successive <span class="hlt">freeze</span>-thaw cycles on beef forelimb were investigated comparing with unfrozen fresh beef for 75 d by keeping at −20±1℃. The <span class="hlt">freeze</span>-thaw cycles were subjected to three thawing methods and carried out to know the best one. As the number of <span class="hlt">freeze</span>-thaw cycles increased color and odor declined significantly before cook within the cycles and tenderness, overall acceptability also declined among the cycles after cook by thawing methods. The thawing loss increased and dripping loss decreased significantly (p<0.05). Water holding capacity (WHC) increased (p<0.05) until two cycles and then decreased. Cooking loss increased in cycle 1 and 3, but decreased in cycle 2. pH decreased significantly (p<0.05) among the cycles. Moreover, drip loss, cooking loss and WHC were affected (p<0.05) by thawing methods within the cycles. 2-Thiobarbituric acid (TBARS) value increased (p<0.05) gradually within the cycles and among the cycles by thawing methods. Total viable bacteria, total coliform and total yeast-mould count decreased significantly (p<0.05) within and among the cycles in comparison to the initial count in repeated <span class="hlt">freeze</span>-thaw cycles. As a result, repeated <span class="hlt">freeze</span>-thaw cycles affected the sensory, physicochemical and microbiological qua- lity of beef, causing the deterioration of beef quality, but improved the microbiological quality. Although repeated <span class="hlt">freeze</span>-thaw cycles did not affect much on beef quality and safety but it may be concluded that repeated <span class="hlt">freeze</span> and thaw should be minimized in terms of beef color for commercial value and WHC and tenderness/juiciness for eating quality. PMID:26761286</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/5518657-plant-moisture-stress-portable-freezing-point-meter-compared-psychrometer','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5518657-plant-moisture-stress-portable-freezing-point-meter-compared-psychrometer"><span>Plant moisture stress: a portable <span class="hlt">freezing</span>-point meter compared with the psychrometer</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Cary, J.W.; Fisher, H.D.</p> <p></p> <p>A small portable instrument for measuring the <span class="hlt">freezing</span>-point depression of plant tissue has been developed for field use. The instrument is easy to operate and can be constructed from materials costing less than $100. Moisture stress measurements made with the <span class="hlt">freezing</span>-point meter on a variety of plants were compared with vapor pressure psychrometer measurements. Variation between duplicates in the <span class="hlt">freezing</span> point averaged 1.2 bars, but differences between stress measurements made with the psychrometer and <span class="hlt">freezing</span>-point instrument averaged 2.6 bars. 11 references, 5 figures, 2 tables.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998PhDT........98J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998PhDT........98J"><span>Stress, deformation and micromorphological aspects of soil <span class="hlt">freezing</span> under laboratory conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jetchick, Elizabeth</p> <p></p> <p>In this thesis, frost heave is viewed as a process resulting from the interactions between thermodynamic conditions, soil environment controls such as texture, stress/deformation conditions and soil microstructure. A series of laboratory experiments was devised to investigate the links between these aspects. Because a limited number of studies exist on the development of internal stresses and strains in <span class="hlt">freezing</span> soil, the work focussed on obtaining rheological data using conventional soil strain gauges and prototype stress transducers. A fine-grained unstructured silt was placed in a column (30 cm diameter by 100 cm length) and subjected to <span class="hlt">freezing</span> and <span class="hlt">freeze</span>-thaw cycles from the top down, lasting up to three months. Heat and water flows, as well as stresses and strains were monitored. The frozen soil was sectioned at the end of four of the experiments to examine the soil fabrics that had developed. From the experimental results, schematic stress and strain curves are proposed. For a single <span class="hlt">freeze</span> cycle, compressive normal and tensile normal stresses were recorded simultaneously by the measuring devices within the <span class="hlt">freezing</span> soil profile. Ice lens inception took place when the stress field changed, a condition which occurred either at the frost front level or at the base of the growing ice lens. Negative and positive strains reflected the different stress states that were sustained below and above the <span class="hlt">freezing</span> front. Negative strains or soil consolidation took place as stresses increased before the passage of the frost line. Negligible soil strains were recorded as maximum soil consolidation was attained, before soil expansion. Distinct positive strain patterns indicating secondary and continuing heave, were recorded simultaneously throughout a thickness of soil, over a range of temperatures. Ice lens growth mostly took place as secondary frost heave, but continuing heave was measured, and the temperature conditions for both types of heave were determined. During</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=poverty+AND+disaster&pg=5&id=EJ900502','ERIC'); return false;" href="https://eric.ed.gov/?q=poverty+AND+disaster&pg=5&id=EJ900502"><span>The 2007 California Citrus <span class="hlt">Freeze</span>: Vulnerability, Poverty, and Unemployment Issues of Farmworkers</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Orozco, Graciela Leon</p> <p>2010-01-01</p> <p>In January of 2007, <span class="hlt">freezing</span> temperatures destroyed citrus and vegetable crops in California. By May 2007, more than 9,000 <span class="hlt">freeze</span>-related unemployment applications had been fled. Through face-to-face interviews, this study documents the experience of 63 farmworkers to find out how they survived the <span class="hlt">freeze</span> and accessed services. Findings revealed…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790025062','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790025062"><span>System noise analysis of the dumbbell tethered satellite for gravity-<span class="hlt">gradient</span> measurements</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Colombo, G.</p> <p>1979-01-01</p> <p>An analysis of the dumbbell gravity gradiometer concept for measuring short wavelength variations in the earth's gravity <span class="hlt">gradient</span> is presented. Variations in the <span class="hlt">gradient</span> are recorded by measuring tension variations in a <span class="hlt">vertically</span> stabilized satellite consisting of heavy masses connected by a long wire or rod. Tension noise arises from the excitation of various mechanical oscillations of the system. The principal noise sources that were identified are fluctuations in atmospheric drag heating and drag force resulting from density variations and winds. Approximate analytical expressions are presented for the tension noise as a function of the system design parameters for various possible configurations. Computer simulations using numerical integration were performed to study the tension noise for several sample cases. Three designs consistent with Shuttle launch capabilities are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1987IJBm...31..191D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987IJBm...31..191D"><span>Effect of demedullation on <span class="hlt">freezing</span> injury in hind limbs of rats</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dhingra, Shashi; Bhatia, B.; Chhina, G. S.; Singh, Baldev</p> <p>1987-09-01</p> <p><span class="hlt">Freezing</span> incidence and tissue loss on exposure of hind limbs of female Wistar rats to <span class="hlt">freezing</span> mixture was reduced by demedullation 6 days prior to cold exposure (p<0.01 and p<0.001 respectively); demedullation 1 h after <span class="hlt">freezing</span> injury had no effect on tissue loss. Noradrenaline (1 mg/kg i.p.) 5 min before exposure increased the <span class="hlt">freezing</span> incidence in intact (p<0.05) as well as in demedullated rats (p<0.01), with no effect on tissue loss. Adrenaline (500 mg/kg i.p.) had no effect on either. A sustained fall in plasma adrenaline after demedullation leading to reduced reactivity of the blood vessels to some vasoactive agents is postulated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/1982/1016/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/1982/1016/report.pdf"><span><span class="hlt">Vertical</span> movement of ground water under the Merrill Field landfill, Anchorage, Alaska</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Nelson, Gordon L.; Dearborn, L.L.</p> <p>1982-01-01</p> <p>Shallow groundwater under the Merrill Field sanitary landfill at Anchorage is polluted by leachate. Wells, including three Municipal-supply wells, obtain water from two confined aquifers 100-300 feet beneath the landfill area. Aquifer-test data and information on subsurface geology, ground-water levels, and properties of materials were used to estimate <span class="hlt">vertical</span> <span class="hlt">gradients</span> and <span class="hlt">vertical</span> permeabilities under the landfill. The authors ' best estimates ' of <span class="hlt">vertical</span> permeabilities of two confining units are 1 x 10 super -2 foot per day and 2 x 10 super -4 foot per day. Theoretical travel-time calculations indicate that minor amounts of pollutants may reach the upper confined aquifer after many tens of years, but that water of the composition of the leachate probably would not reach the aquifer for more than three centuries. The range of error in the theoretical travel-time calculations is likely to be plus or minus a factor of two or three. (USGS)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23719856','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23719856"><span>Role of cells in <span class="hlt">freezing</span>-induced cell-fluid-matrix interactions within engineered tissues.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Seawright, Angela; Ozcelikkale, Altug; Dutton, Craig; Han, Bumsoo</p> <p>2013-09-01</p> <p>During cryopreservation, ice forms in the extracellular space resulting in <span class="hlt">freezing</span>-induced deformation of the tissue, which can be detrimental to the extracellular matrix (ECM) microstructure. Meanwhile, cells dehydrate through an osmotically driven process as the intracellular water is transported to the extracellular space, increasing the volume of fluid for <span class="hlt">freezing</span>. Therefore, this study examines the effects of cellular presence on tissue deformation and investigates the significance of intracellular water transport and cell-ECM interactions in <span class="hlt">freezing</span>-induced cell-fluid-matrix interactions. <span class="hlt">Freezing</span>-induced deformation characteristics were examined through cell image deformetry (CID) measurements of collagenous engineered tissues embedded with different concentrations of MCF7 breast cancer cells versus microspheres as their osmotically inactive counterparts. Additionally, the development of a biophysical model relates the <span class="hlt">freezing</span>-induced expansion of the tissue due to the cellular water transport and the extracellular <span class="hlt">freezing</span> thermodynamics for further verification. The magnitude of the <span class="hlt">freezing</span>-induced dilatation was found to be not affected by the cellular water transport for the cell concentrations considered; however, the deformation patterns for different cell concentrations were different suggesting that cell-matrix interactions may have an effect. It was, therefore, determined that intracellular water transport during <span class="hlt">freezing</span> was insignificant at the current experimental cell concentrations; however, it may be significant at concentrations similar to native tissue. Finally, the cell-matrix interactions provided mechanical support on the ECM to minimize the expansion regions in the tissues during <span class="hlt">freezing</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21530113','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21530113"><span>Changes in the structures of motile sperm subpopulations in dog spermatozoa after both cryopreservation and centrifugation on PureSperm(®) <span class="hlt">gradient</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dorado, J; Alcaráz, L; Duarte, N; Portero, J M; Acha, D; Hidalgo, M</p> <p>2011-05-01</p> <p>The aims of the present study were to: (1) determine if discrete motile sperm subpopulations exist and their incidence in fresh dog ejaculates, (2) evaluate the effects of cryopreservation on the distribution of spermatozoa within the different subpopulations, and (3) determine the effect of the discontinuous PureSperm(®) <span class="hlt">gradient</span> on the sperm subpopulation structure of frozen-thawed dog spermatozoa. Semen from 5 dogs were collected and cryopreserved following a standard protocol. After thawing, semen samples were selected by centrifugation on PureSperm(®). Sperm motility (assessed by computerized-assisted semen analysis, CASA) was assessed before <span class="hlt">freezing</span>, just after thawing and after preparation on the PureSperm(®) <span class="hlt">gradients</span>. Cryopreservation had a significant (P<0.001) effect on CASA-derived parameters. PureSperm(®) centrifugation yielded sperm suspensions with improved motility (P<0.01). A multivariate clustering procedure separated 19414 motile spermatozoa into four subpopulations: Subpopulation 1 consisting of poorly active and non-progressive spermatozoa (20.97%), Subpopulation 2 consisting of slow and low-linear spermatozoa (18.24%), Subpopulation 3 consisting of highly active but non-progressive spermatozoa (20.75%), and Subpopulation 4 consisting of high speed and progressive spermatozoa (40.03%). Although, cryopreservation had a significant (P<0.001) effect on both the frequency distribution of spermatozoa within subpopulations and the motion characteristics of each subpopulation, the sperm subpopulation structure was perfectly maintained after <span class="hlt">freezing</span> and thawing. The selected sperm samples was enrich in Subpopulation 4, reaching a proportion of 31.9% of the present spermatozoa, in contrast with the unselected sperm samples, where this sperm subpopulation accounted for 24.9% of the total. From these results, we concluded that four well-defined motile sperm subpopulations were present either in fresh semen, in unselected sperm samples or in selected</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2989305','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2989305"><span>Saccharomyces cerevisiae glycerol/H+ symporter Stl1p is essential for cold/near-<span class="hlt">freeze</span> and <span class="hlt">freeze</span> stress adaptation. A simple recipe with high biotechnological potential is given</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2010-01-01</p> <p>Background <span class="hlt">Freezing</span> is an increasingly important means of preservation and storage of microbial strains used for many types of industrial applications including food processing. However, the yeast mechanisms of tolerance and sensitivity to <span class="hlt">freeze</span> or near-<span class="hlt">freeze</span> stress are still poorly understood. More knowledge on this regard would improve their biotechnological potential. Glycerol, in particular intracellular glycerol, has been assigned as a cryoprotectant, also important for cold/near-<span class="hlt">freeze</span> stress adaptation. The S. cerevisiae glycerol active transporter Stl1p plays an important role on the fast accumulation of glycerol. This gene is expressed under gluconeogenic conditions, under osmotic shock and stress, as well as under high temperatures. Results We found that cells grown on STL1 induction medium (YPGE) and subjected to cold/near-<span class="hlt">freeze</span> stress, displayed an extremely high expression of this gene, also visible at glycerol/H+ symporter activity level. Under the same conditions, the strains harbouring this transporter accumulated more than 400 mM glycerol, whereas the glycerol/H+ symporter mutant presented less than 1 mM. Consistently, the strains able to accumulate glycerol survive 25-50% more than the stl1Δ mutant. Conclusions In this work, we report the contribution of the glycerol/H+ symporter Stl1p for the accumulation and maintenance of glycerol intracellular levels, and consequently cell survival at cold/near-<span class="hlt">freeze</span> and <span class="hlt">freeze</span> temperatures. These findings have a high biotechnological impact, as they show that any S. cerevisiae strain already in use can become more resistant to cold/<span class="hlt">freeze</span>-thaw stress just by simply adding glycerol to the broth. The combination of low temperatures with extracellular glycerol will induce the transporter Stl1p. This solution avoids the use of transgenic strains, in particular in food industry. PMID:21047428</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22960322','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22960322"><span>Protein spheres prepared by drop jet <span class="hlt">freeze</span> drying.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Eggerstedt, Sören N; Dietzel, Mathias; Sommerfeld, Martin; Süverkrüp, Richard; Lamprecht, Alf</p> <p>2012-11-15</p> <p>In spray <span class="hlt">freeze</span> drying (SFD) solutions are frozen by spraying into a very cold environment and subsequently dried by sublimation. In contrast to conventional <span class="hlt">freeze</span> drying, spray <span class="hlt">freeze</span> drying has the possibility to produce flowable lyophilizates which offers a variety of new pharmaceutical applications. Here, a drop jet nozzle is proposed as liquid dispenser that is able to produce droplets with a very narrow size distribution compared to standard methods. The drop jet nozzle is mounted in a spray tower designed to prevent direct contact of the product with the <span class="hlt">freezing</span> medium. Various formulations have been tested containing lysozyme as model protein and stabilizers such as bovine serum albumin, polyvinylpyrrolidone or dextran in various concentrations and mannitol. Excellent free flowing and nearly monodispersed, porous particles are produced where particle properties can be controlled by formulation and process conditions. The particle diameter varied between 231 ± 3 μm and 310 ± 10 μm depending on the formulation composition. The lysozyme activity was >94 ± 5% for all formulations exhibiting a full preservation of enzyme activity. This new method is very promising for the production of nearly monodisperse particulate lyophilizates in various therapeutic applications. Copyright © 2012 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011TRACE..25..291T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011TRACE..25..291T"><span>A New <span class="hlt">Freezing</span> Method Using Pre-Dehydration by Microwave-Vacuum Drying</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tsuruta, Takaharu; Hamidi, Nurkholis</p> <p></p> <p>Partial dehydration by microwave-vacuum drying has been applied to tuna and strawberry in order to reduce cell-damages caused by the formation of large ice-crystals during <span class="hlt">freezing</span>. The samples were subjected to microwave vacuum drying at pressure of 5 kPa and temperature less than 27°C to remove small amount of water prior to <span class="hlt">freezing</span>. The tuna were cooled by using the <span class="hlt">freezing</span> chamber at temperature -50°C or -150°C, while the strawberries were frozen at temperature -30°C or -80°C, respectively. The temperature transients in tuna showed that removing some water before <span class="hlt">freezing</span> made the <span class="hlt">freezing</span> time shorter. The observations of ice crystal clearly indicated that rapid cooling and pre-dehydration prior to <span class="hlt">freezing</span> were effective in minimizing the size of ice crystal. It is also understood that the formation of large ice crystals has a close relation to the cell damages. After thawing, the observation of microstructure was done on the tuna and strawberry halves. The pre-dehydrated samples showed a better structure than the un-dehydrated one. It is concluded that the pre-dehydration by microwave-vacuum drying is one promising method for the cryo-preservation of foods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23432539','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23432539"><span>Toward intradermal vaccination: preparation of powder formulations by collapse <span class="hlt">freeze</span>-drying.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Etzl, Elsa E; Winter, Gerhard; Engert, Julia</p> <p>2014-03-01</p> <p>Intradermal powder immunization is an emerging technique in vaccine delivery. The purpose of this study was to generate powder particles for intradermal injection by <span class="hlt">freeze</span>-drying and subsequent cryo-milling. Two different <span class="hlt">freeze</span>-drying protocols were compared, a moderate <span class="hlt">freeze</span>-drying cycle and an aggressive <span class="hlt">freeze</span>-drying cycle, which induced a controlled collapse of the sugar matrix. Ovalbumin served as model antigen. The influence of collapse drying and cryo-milling on particle morphology and protein stability was investigated. Cryo-milling generated irregularly shaped particles of size 20-70 µm. The recovery of soluble monomer of ovalbumin was not changed during <span class="hlt">freeze</span>-drying and after cryo-milling, or after 12 months of storage at 2-8 °C. A slight increase in higher molecular weight aggregates was found in formulations containing the polymer dextran after 12 months of storage at 50 °C. Light obscuration measurements showed an increase in cumulative particle counts after cryo-milling that did not further increase during storage at 2-8 °C for 12 months. The applicability of the cryo-milling process to other therapeutic proteins was shown using recombinant human granulocyte-colony stimulating factor. Collapse <span class="hlt">freeze</span>-drying and subsequent cryo-milling allows the generation of particles suitable for intradermal powder injection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020046931&hterms=al+gore&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dal%2Bgore','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020046931&hterms=al+gore&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dal%2Bgore"><span>Simulations of Polar Stratospheric Clouds and Denitrification Using Laboratory <span class="hlt">Freezing</span> Rates</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Drdla, Katja; Tabazadeh, Azadeh; Gore, Warren J. (Technical Monitor)</p> <p>2001-01-01</p> <p>During the 1999-2000 Arctic winter, the SAGE (Stratospheric Aerosol and Gas Experiment) III Ozone Loss and Validation Experiment (SOLVE) provided evidence of widespread solid-phase polar stratospheric clouds (PSCs) accompanied by severe nitrification. Previous simulations have shown that a <span class="hlt">freezing</span> process occurring at temperatures above the ice frost point is necessary to explain these observations. In this work, the nitric acid <span class="hlt">freezing</span> rates measured by Salcedo et al. and discussed by Tabazadeh et al. have been examined. These <span class="hlt">freezing</span> rates have been tested in winter-long microphysical simulations of the 1999-2000 Arctic vortex evolution in order to determine whether they can explain the observations. A range of cases have been explored, including whether the PSC particles are composed of nitric acid dihydrate or trihydrate, whether the <span class="hlt">freezing</span> process is a bulk process or occurs only on the particle surfaces, and uncertainties in the derived <span class="hlt">freezing</span> rates. Finally, the possibility that meteoritic debris enhances the <span class="hlt">freezing</span> rate has also been examined. The results of these simulations have been compared with key PSC and denitrification measurements made by the SOLVE campaign. The cases that best reproduce the measurements will he highlighted, with a discussion of the implications for our understanding of PSCs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26760458','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26760458"><span>Destabilization of mayonnaise induced by lipid crystallization upon <span class="hlt">freezing</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Miyagawa, Yayoi; Ogawa, Takenobu; Nakagawa, Kyuya; Adachi, Shuji</p> <p>2016-01-01</p> <p>The thermal and rheological history of mayonnaise during <span class="hlt">freezing</span> and its dispersion stability after the <span class="hlt">freeze</span>-thaw process were investigated. Mayonnaise was cooled to <span class="hlt">freeze</span> and stored at -20 to -40 °C while monitoring the temperature; penetration tests were conducted on the mayonnaise, which was sampled at selected times during isothermal storage at -20 °C. Significant increases in the temperature and stress values due to water-phase crystallization and subsequent oil-phase crystallization were observed. The water phase crystallized during the cooling step in all the tested mayonnaise samples. The oil phases of the prepared mayonnaise (with rapeseed oil) and commercial mayonnaise crystallized during isothermal storage after 6 and 4 h, respectively, at -20 °C. The dispersion stability was evaluated from the separation ratio, which was defined as the weight ratio of separated oil after centrifuging to the total amount of oil in the commercial mayonnaise. The separation ratio rapidly increased after 4 h of <span class="hlt">freezing</span>. This result suggests that crystallization of the oil phase is strongly related to the dispersion stability of mayonnaise.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009cct1.book..307T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009cct1.book..307T"><span>Monitoring <span class="hlt">Freeze</span> Injury and Evaluating Losingto Sugar-Cane Using RS and GPS</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tan, Zongkun; Ding, Meihua; Wang, Longhe; Yang, Xin; Ou, Zhaorong</p> <p></p> <p>From Jan 12th to Feb 12th 2008, the most severity cold chilling and <span class="hlt">freeze</span> injury weather took place during the last 50 years in the southern of China.Sugar-cane was suffered injury severity. However, the losing of sugar-cane which it was aroused by thisweather disaster had not been exactitude evaluated till on Apr 1st, 2008. It was not only affected the sugar-cane ordinary harvesting and crushing, but also affected reserving sugar-cane seed for planting. <span class="hlt">Freeze</span> injury is common disaster for sugar-cane in southern of China and monitoring <span class="hlt">freeze</span> injury using RS and GIS are of great economic significance but little research work about it has been done in China <span class="hlt">Freeze</span> injuring is not only related to crop growth stage and the cold air intension from northern to southern and weather types, but also consanguineous related to land form and physiognomy and geographical latitude and height above sea level etc and crop planting spatial distribution. The case study of Guangxi province which is the biggest region of sugar-cane planting in China in this paper, the values of sugar-cane NDVI among the <span class="hlt">freeze</span> injury occur former and after in early 2008 and without <span class="hlt">freeze</span> injury occur in the same term 2007 were analyzed and compared based on the sugar-cane planting spatial distribution information which were carried out by using multi-phase EOS/MODIS data. The result showed that it was not only commendably reflected the spatial distribution of <span class="hlt">freeze</span> injury but also reflected the sugarcane suffered from degree using the values of sugar-cane NDVIof <span class="hlt">freeze</span> injury occur former and after. The field sample investigation data of using GPS was integrated with the NDVI, the evaluation of region sugar-cane suffer from <span class="hlt">freeze</span> injury losing could quickly and exactly realize.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=%22food+processing%22&id=EJ876953','ERIC'); return false;" href="https://eric.ed.gov/?q=%22food+processing%22&id=EJ876953"><span>Gelatin-Filtered Consomme: A Practical Demonstration of the <span class="hlt">Freezing</span> and Thawing Processes</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Lahne, Jacob B.; Schmidt, Shelly J.</p> <p>2010-01-01</p> <p><span class="hlt">Freezing</span> is a key food processing and preservation technique widely used in the food industry. Application of best <span class="hlt">freezing</span> and storage practices extends the shelf-life of foods for several months, while retaining much of the original quality of the fresh food. During <span class="hlt">freezing</span>, as well as its counterpart process, thawing, a number of critical…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MolPh.113.2725K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MolPh.113.2725K"><span><span class="hlt">Freezing</span> point depression in model Lennard-Jones solutions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koschke, Konstantin; Jörg Limbach, Hans; Kremer, Kurt; Donadio, Davide</p> <p>2015-09-01</p> <p>Crystallisation of liquid solutions is of uttermost importance in a wide variety of processes in materials, atmospheric and food science. Depending on the type and concentration of solutes the <span class="hlt">freezing</span> point shifts, thus allowing control on the thermodynamics of complex fluids. Here we investigate the basic principles of solute-induced <span class="hlt">freezing</span> point depression by computing the melting temperature of a Lennard-Jones fluid with low concentrations of solutes, by means of equilibrium molecular dynamics simulations. The effect of solvophilic and weakly solvophobic solutes at low concentrations is analysed, scanning systematically the size and the concentration. We identify the range of parameters that produce deviations from the linear dependence of the <span class="hlt">freezing</span> point on the molal concentration of solutes, expected for ideal solutions. Our simulations allow us also to link the shifts in coexistence temperature to the microscopic structure of the solutions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JPCM...30u5701D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JPCM...30u5701D"><span>Local deformation <span class="hlt">gradients</span> in epitaxial Pb(Zr0.2Ti0.8)O3 layers investigated by transmission electron microscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Denneulin, T.; Wollschläger, N.; Everhardt, A. S.; Farokhipoor, S.; Noheda, B.; Snoeck, E.; Hÿtch, M.</p> <p>2018-05-01</p> <p>Lead zirconate titanate samples are used for their piezoelectric and ferroelectric properties in various types of micro-devices. Epitaxial layers of tetragonal perovskites have a tendency to relax by forming ferroelastic domains. The accommodation of the a/c/a/c polydomain structure on a flat substrate leads to nanoscale deformation <span class="hlt">gradients</span> which locally influence the polarization by flexoelectric effect. Here, we investigated the deformation fields in epitaxial layers of Pb(Zr0.2Ti0.8)O3 grown on SrTiO3 substrates using transmission electron microscopy (TEM). We found that the deformation <span class="hlt">gradients</span> depend on the domain walls inclination ( or to the substrate interface) of the successive domains and we describe three different a/c/a domain configurations: one configuration with parallel a-domains and two configurations with perpendicular a-domains (V-shaped and hat--shaped). In the parallel configuration, the c-domains contain horizontal and <span class="hlt">vertical</span> <span class="hlt">gradients</span> of out-of-plane deformation. In the V-shaped and hat--shaped configurations, the c-domains exhibit a bending deformation field with <span class="hlt">vertical</span> <span class="hlt">gradients</span> of in-plane deformation. Each of these configurations is expected to have a different influence on the polarization and so the local properties of the film. The deformation <span class="hlt">gradients</span> were measured using dark-field electron holography, a TEM technique, which offers a good sensitivity (0.1%) and a large field-of-view (hundreds of nanometers). The measurements are compared with finite element simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040171616','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040171616"><span>Nucleation in Synoptically Forced Cirrostratus</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lin, R.-F.; Starr, D. OC.; Reichardt, J.; DeMott, P. J.</p> <p>2004-01-01</p> <p>Formation and evolution of cirrostratus in response to weak, uniform and constant synoptic forcing is simulated using a one-dimensional numerical model with explicit microphysics, in which the particle size distribution in each grid box is fully resolved. A series of tests of the model response to nucleation modes (homogeneous-<span class="hlt">freezing</span>-only/heterogeneous nucleation) and heterogeneous nucleation parameters are performed. In the case studied here, nucleation is first activated in the prescribed moist layer. A continuous cloud-top nucleation zone with a depth depending on the <span class="hlt">vertical</span> humidity <span class="hlt">gradient</span> and one of the nucleation parameters is developed afterward. For the heterogeneous nucleation cases, intermittent nucleation zones in the mid-upper portion of the cloud form where the relative humidity is on the rise, because existent ice crystals do not uptake excess water vapor efficiently, and ice nuclei (IN) are available. <span class="hlt">Vertical</span> resolution as fine as 1 m is required for realistic simulation of the homogeneous-<span class="hlt">freezing</span>-only scenario, while the model resolution requirement is more relaxed in the cases where heterogeneous nucleation dominates. Bulk microphysical and optical properties are evaluated and compared. Ice particle number flux divergence, which is due to the <span class="hlt">vertical</span> <span class="hlt">gradient</span> of the gravity-induced particle sedimentation, is constantly and rapidly changing the local ice number concentration, even in the nucleation zone. When the depth of the nucleation zone is shallow, particle number concentration decreases rapidly as ice particles grow and sediment away from the nucleation zone. When the depth of the nucleation zone is large, a region of high ice number concentration can be sustained. The depth of nucleation zone is an important parameter to be considered in parametric treatments of ice cloud generation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19492339','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19492339"><span>Ice nucleation temperature influences recovery of activity of a model protein after <span class="hlt">freeze</span> drying.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cochran, Teresa; Nail, Steven L</p> <p>2009-09-01</p> <p>The objective of this study was to determine whether a relationship exists between ice nucleation temperature and recovery of activity of a model protein, lactate dehydrogenase, after <span class="hlt">freeze</span> drying. Aqueous buffer systems containing 50 microg/mL of protein were frozen in vials with externally mounted thermocouples on the shelf of a <span class="hlt">freeze</span> dryer, then <span class="hlt">freeze</span> dried. Various methods were used to establish a wide range of ice nucleation temperatures. An inverse relationship was found between the extent of supercooling during <span class="hlt">freezing</span> and recovery of activity in the reconstituted solution. The data are consistent with a mechanism of inactivation resulting from adsorption of protein at the ice/<span class="hlt">freeze</span>-concentrate interface during the <span class="hlt">freezing</span> process.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <div class="footer-extlink text-muted" style="margin-bottom:1rem; text-align:center;">Some links on this page may take you to non-federal websites. 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