Fundamental solutions to the bioheat equation and their application to magnetic fluid hyperthermia.

PubMed

Giordano, Mauricio A; Gutierrez, Gustavo; Rinaldi, Carlos

2010-01-01

Methods of predicting temperature profiles during local hyperthermia treatment are very important to avoid damage to healthy tissue. With this aim, fundamental solutions of Pennes' bioheat equation are derived in rectangular, cylindrical, and spherical coordinates. The medium is idealised as isotropic with effective thermal properties. Temperature distributions due to space- and time-dependent heat sources are obtained by the solution method presented. Applications of the fundamental solutions are addressed with emphasis on a particular problem of Magnetic Fluid Hyperthermia (MFH) consisting of a thin shell of magnetic nanoparticles in the outer surface of a spherical solid tumour. It is observed from the solution of this particular problem that the temperature profiles are strongly dependent on the distribution of the magnetic nanoparticles within the tissue. An almost uniform temperature profile is obtained inside the tumour with little penetration of therapeutic temperatures to the outer region of healthy tissue. The fundamental solutions obtained can be used to develop boundary element methods to predict temperature profiles with more complicated geometries.

Unsteady free convection flow of viscous fluids with analytical results by employing time-fractional Caputo-Fabrizio derivative (without singular kernel)

NASA Astrophysics Data System (ADS)

Ali Shah, Nehad; Mahsud, Yasir; Ali Zafar, Azhar

2017-10-01

This article introduces a theoretical study for unsteady free convection flow of an incompressible viscous fluid. The fluid flows near an isothermal vertical plate. The plate has a translational motion with time-dependent velocity. The equations governing the fluid flow are expressed in fractional differential equations by using a newly defined time-fractional Caputo-Fabrizio derivative without singular kernel. Explicit solutions for velocity, temperature and solute concentration are obtained by applying the Laplace transform technique. As the fractional parameter approaches to one, solutions for the ordinary fluid model are extracted from the general solutions of the fractional model. The results showed that, for the fractional model, the obtained solutions for velocity, temperature and concentration exhibit stationary jumps discontinuity across the plane at t=0 , while the solutions are continuous functions in the case of the ordinary model. Finally, numerical results for flow features at small-time are illustrated through graphs for various pertinent parameters.

Revisiting the Fundamental Analytical Solutions of Heat and Mass Transfer: The Kernel of Multirate and Multidimensional Diffusion

NASA Astrophysics Data System (ADS)

Zhou, Quanlin; Oldenburg, Curtis M.; Rutqvist, Jonny; Birkholzer, Jens T.

2017-11-01

There are two types of analytical solutions of temperature/concentration in and heat/mass transfer through boundaries of regularly shaped 1-D, 2-D, and 3-D blocks. These infinite-series solutions with either error functions or exponentials exhibit highly irregular but complementary convergence at different dimensionless times, td. In this paper, approximate solutions were developed by combining the error-function-series solutions for early times and the exponential-series solutions for late times and by using time partitioning at the switchover time, td0. The combined solutions contain either the leading term of both series for normal-accuracy approximations (with less than 0.003 relative error) or the first two terms for high-accuracy approximations (with less than 10-7 relative error) for 1-D isotropic (spheres, cylinders, slabs) and 2-D/3-D rectangular blocks (squares, cubes, rectangles, and rectangular parallelepipeds). This rapid and uniform convergence for rectangular blocks was achieved by employing the same time partitioning with individual dimensionless times for different directions and the product of their combined 1-D slab solutions. The switchover dimensionless time was determined to minimize the maximum approximation errors. Furthermore, the analytical solutions of first-order heat/mass flux for 2-D/3-D rectangular blocks were derived for normal-accuracy approximations. These flux equations contain the early-time solution with a three-term polynomial in √td and the late-time solution with the limited-term exponentials for rectangular blocks. The heat/mass flux equations and the combined temperature/concentration solutions form the ultimate kernel for fast simulations of multirate and multidimensional heat/mass transfer in porous/fractured media with millions of low-permeability blocks of varying shapes and sizes.

Revisiting the Fundamental Analytical Solutions of Heat and Mass Transfer: The Kernel of Multirate and Multidimensional Diffusion

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

Zhou, Quanlin; Oldenburg, Curtis M.; Rutqvist, Jonny

There are two types of analytical solutions of temperature/concentration in and heat/mass transfer through boundaries of regularly shaped 1D, 2D, and 3D blocks. These infinite-series solutions with either error functions or exponentials exhibit highly irregular but complementary convergence at different dimensionless times, t d0. In this paper, approximate solutions were developed by combining the error-function-series solutions for early times and the exponential-series solutions for late times and by using time partitioning at the switchover time, t d0. The combined solutions contain either the leading term of both series for normal-accuracy approximations (with less than 0.003 relative error) or the firstmore » two terms for high-accuracy approximations (with less than 10-7 relative error) for 1D isotropic (spheres, cylinders, slabs) and 2D/3D rectangular blocks (squares, cubes, rectangles, and rectangular parallelepipeds). This rapid and uniform convergence for rectangular blocks was achieved by employing the same time partitioning with individual dimensionless times for different directions and the product of their combined 1D slab solutions. The switchover dimensionless time was determined to minimize the maximum approximation errors. Furthermore, the analytical solutions of first-order heat/mass flux for 2D/3D rectangular blocks were derived for normal-accuracy approximations. These flux equations contain the early-time solution with a three-term polynomial in √td and the late-time solution with the limited-term exponentials for rectangular blocks. The heat/mass flux equations and the combined temperature/concentration solutions form the ultimate kernel for fast simulations of multirate and multidimensional heat/mass transfer in porous/fractured media with millions of low-permeability blocks of varying shapes and sizes.« less

Revisiting the Fundamental Analytical Solutions of Heat and Mass Transfer: The Kernel of Multirate and Multidimensional Diffusion

DOE PAGES

Zhou, Quanlin; Oldenburg, Curtis M.; Rutqvist, Jonny; ...

2017-10-24

There are two types of analytical solutions of temperature/concentration in and heat/mass transfer through boundaries of regularly shaped 1D, 2D, and 3D blocks. These infinite-series solutions with either error functions or exponentials exhibit highly irregular but complementary convergence at different dimensionless times, t d0. In this paper, approximate solutions were developed by combining the error-function-series solutions for early times and the exponential-series solutions for late times and by using time partitioning at the switchover time, t d0. The combined solutions contain either the leading term of both series for normal-accuracy approximations (with less than 0.003 relative error) or the firstmore » two terms for high-accuracy approximations (with less than 10-7 relative error) for 1D isotropic (spheres, cylinders, slabs) and 2D/3D rectangular blocks (squares, cubes, rectangles, and rectangular parallelepipeds). This rapid and uniform convergence for rectangular blocks was achieved by employing the same time partitioning with individual dimensionless times for different directions and the product of their combined 1D slab solutions. The switchover dimensionless time was determined to minimize the maximum approximation errors. Furthermore, the analytical solutions of first-order heat/mass flux for 2D/3D rectangular blocks were derived for normal-accuracy approximations. These flux equations contain the early-time solution with a three-term polynomial in √td and the late-time solution with the limited-term exponentials for rectangular blocks. The heat/mass flux equations and the combined temperature/concentration solutions form the ultimate kernel for fast simulations of multirate and multidimensional heat/mass transfer in porous/fractured media with millions of low-permeability blocks of varying shapes and sizes.« less

Inorganic-polymer-derived dielectric films

DOEpatents

Brinker, C. Jeffrey; Keefer, Keith D.; Lenahan, Patrick M.

1987-01-01

A method of coating a substrate with a thin film of a polymer of predetermined porosity comprises depositing the thin film on the substrate from a non-gelled solution comprising at least one hydrolyzable metal alkoxide of a polymeric network forming cation, water, an alcohol compatible with the hydrolysis and the polymerization of the metal alkoxide, and an acid or a base, prior to depositing the film, controlling the structure of the polymer for a given composition of the solution exclusive of the acid or base component and the water component, (a) by adjusting each of the water content, the pH, and the temperature to obtain the desired concentration of alkoxide, and then adjusting the time of standing of the solution prior to lowering the temperature of the solution, and (b) lowering the temperature of the solution after the time of standing to about 15 degrees C. or lower to trap the solution in a state in which, after the depositing step, a coating of the desired porosity will be obtained, and curing the deposited film at a temperature effective for curing whereby there is obtained a thin film of a polymer of a predetermined porosity and corresponding pore size on the substrate.

Osmotic potential calculations of inorganic and organic aqueous solutions over wide solute concentration levels and temperatures.

PubMed

Cochrane, T T; Cochrane, T A

2016-01-01

To demonstrate that the authors' new "aqueous solution vs pure water" equation to calculate osmotic potential may be used to calculate the osmotic potentials of inorganic and organic aqueous solutions over wide ranges of solute concentrations and temperatures. Currently, the osmotic potentials of solutions used for medical purposes are calculated from equations based on the thermodynamics of the gas laws which are only accurate at low temperature and solute concentration levels. Some solutions used in medicine may need their osmotic potentials calculated more accurately to take into account solute concentrations and temperatures. The authors experimented with their new equation for calculating the osmotic potentials of inorganic and organic aqueous solutions up to and beyond body temperatures by adjusting three of its factors; (a) the volume property of pure water, (b) the number of "free" water molecules per unit volume of solution, "Nf," and (c) the "t" factor expressing the cooperative structural relaxation time of pure water at given temperatures. Adequate information on the volume property of pure water at different temperatures is available in the literature. However, as little information on the relative densities of inorganic and organic solutions, respectively, at varying temperatures needed to calculate Nf was available, provisional equations were formulated to approximate values. Those values together with tentative t values for different temperatures chosen from values calculated by different workers were substituted into the authors' equation to demonstrate how osmotic potentials could be estimated over temperatures up to and beyond bodily temperatures. The provisional equations formulated to calculate Nf, the number of free water molecules per unit volume of inorganic and organic solute solutions, respectively, over wide concentration ranges compared well with the calculations of Nf using recorded relative density data at 20 °C. They were subsequently used to estimate Nf values at temperatures up to and excess of body temperatures. Those values, together with t values at temperatures up to and in excess of body temperatures recorded in the literature, were substituted in the authors' equation for the provisional calculation of osmotic potentials. The calculations indicated that solution temperatures and solute concentrations have a marked effect on osmotic potentials. Following work to measure the relative densities of aqueous solutions for the calculation of Nf values and the determination of definitive t values up to and beyond bodily temperatures, the authors' equation would enable the accurate estimations of the osmotic potentials of wide concentrations of aqueous solutions of inorganic and organic solutes over the temperature range. The study illustrates that not only solute concentrations but also temperatures have a marked effect on osmotic potentials, an observation of medical and biological significance.

Effects of two-temperature parameter and thermal nonlocal parameter on transient responses of a half-space subjected to ramp-type heating

NASA Astrophysics Data System (ADS)

Xue, Zhang-Na; Yu, Ya-Jun; Tian, Xiao-Geng

2017-07-01

Based upon the coupled thermoelasticity and Green and Lindsay theory, the new governing equations of two-temperature thermoelastic theory with thermal nonlocal parameter is formulated. To more realistically model thermal loading of a half-space surface, a linear temperature ramping function is adopted. Laplace transform techniques are used to get the general analytical solutions in Laplace domain, and the inverse Laplace transforms based on Fourier expansion techniques are numerically implemented to obtain the numerical solutions in time domain. Specific attention is paid to study the effect of thermal nonlocal parameter, ramping time, and two-temperature parameter on the distributions of temperature, displacement and stress distribution.

Analytical solution of the transient temperature profile in gain medium of passively Q-switched microchip laser.

PubMed

Han, Xiahui; Li, Jianlang

2014-11-01

The transient temperature evolution in the gain medium of a continuous wave (CW) end-pumped passively Q-switched microchip (PQSM) laser is analyzed. By approximating the time-dependent population inversion density as a sawtooth function of time and treating the time-dependent pump absorption of a CW end-pumped PQSM laser as the superposition of an infinite series of short pumping pulses, the analytical expressions of transient temperature evolution and distribution in the gain medium for four- and three-level laser systems, respectively, are given. These analytical solutions are applied to evaluate the transient temperature evolution and distribution in the gain medium of CW end-pumped PQSM Nd:YAG and Yb:YAG lasers.

Real-time measurement system for tracking birefringence, weight, thickness, and surface temperature during drying of solution cast coatings and films

NASA Astrophysics Data System (ADS)

Unsal, E.; Drum, J.; Yucel, O.; Nugay, I. I.; Yalcin, B.; Cakmak, M.

2012-02-01

This paper describes the design and performance of a new instrument to track temporal changes in physical parameters during the drying behavior of solutions, as well as curing of monomers. This real-time instrument follows in-plane and out-of-plane birefringence, weight, thickness, and surface temperature during the course of solidification of coatings and films through solvent evaporation and thermal or photocuring in a controlled atmosphere. It is specifically designed to simulate behavior of polymer solutions inside an industrial size, continuous roll-to-roll solution casting line and other coating operations where resins are subjected to ultraviolet (UV) curing from monomer precursors. Controlled processing parameters include air speed, temperature, initial cast thickness, and solute concentration, while measured parameters are thickness, weight, film temperature, in-plane and out-of-plane birefringence. In this paper, we illustrate the utility of this instrument with solution cast and dried poly (amide-imide)/DMAc (Dimethylacetamide) solution, water based black paint, and organo-modified clay/NMP (N-Methylpyrrolidone) solution. In addition, the physical changes that take place during UV photo polymerization of a monomer are tracked. This instrument is designed to be generic and it can be used for tracking any drying/swelling/solidification systems including paper, foodstuffs such as; grains, milk as well as pharmaceutical thin paste and slurries.

Measurements of liquid film thickness, concentration, and temperature of aqueous urea solution by NIR absorption spectroscopy

NASA Astrophysics Data System (ADS)

Pan, R.; Jeffries, J. B.; Dreier, T.; Schulz, C.

2016-01-01

A multi-wavelength near-infrared (NIR) diode laser absorption sensor has been developed and demonstrated for real-time monitoring of the thickness, solute concentration, and temperature of thin films of urea-water solutions. The sensor monitors the transmittance of three near-infrared diode lasers through the thin liquid film. Film thickness, urea mass fraction, and liquid temperature were determined from measured transmittance ratios of suitable combinations of lasers. Available laser wavelengths were selected depending on the variation of the NIR absorption spectrum of the solution with temperature and solute concentration. The spectral database was measured by a Fourier transform infrared spectrometer in the range 5500-8000 cm-1 for urea solutions between 5 and 40 wt% and temperatures between 298 and 338 K. A prototype sensor was constructed, and the sensor concept was first validated with measurements using a calibration cell providing liquid layers of variable thickness (200-1500 µm), urea mass fraction (5-40 wt%) and temperature (298-318 K). Temporal variations of film thickness and urea concentration were captured during the constant-temperature evaporation of a liquid film deposited on an optically polished heated quartz flat.

Synthesis of sodium lignosulphonate from oil palm empty fruit bunches's lignin

NASA Astrophysics Data System (ADS)

Prakoso, Nurcahyo Iman; Purwono, Suryo; Rochmadi

2017-03-01

Synthesis of sodium lignosulphonate have been done by using batch method. Optimation of synthesis method was achieved through this study. The study was conducted on the optimation of mass ratio of lignin to the NaHSO3 solution, the concentration of NaHSO3 solution, reaction temperature, and reaction time. Of all the treatments, it was found that the optimum mass ratio of lignin to the NaHSO3 solution, concentration of NaHSO3 solution, reaction temperature, and reaction time respectively, 0.3 M, 0.1 M 97 °C, and the reaction was carried out for 4 hours. Excellent yields and selective products were obtained (90-92%)

Was That Assumption Necessary? Reconsidering Boundary Conditions for Analytical Solutions to Estimate Streambed Fluxes

NASA Astrophysics Data System (ADS)

Luce, Charles H.; Tonina, Daniele; Applebee, Ralph; DeWeese, Timothy

2017-11-01

Two common refrains about using the one-dimensional advection diffusion equation to estimate fluid fluxes and thermal conductivity from temperature time series in streambeds are that the solution assumes that (1) the surface boundary condition is a sine wave or nearly so, and (2) there is no gradient in mean temperature with depth. Although the mathematical posing of the problem in the original solution to the problem might lead one to believe these constraints exist, the perception that they are a source of error is a fallacy. Here we develop a mathematical proof demonstrating the equivalence of the solution as developed based on an arbitrary (Fourier integral) surface temperature forcing when evaluated at a single given frequency versus that derived considering a single frequency from the beginning. The implication is that any single frequency can be used in the frequency-domain solutions to estimate thermal diffusivity and 1-D fluid flux in streambeds, even if the forcing has multiple frequencies. This means that diurnal variations with asymmetric shapes or gradients in the mean temperature with depth are not actually assumptions, and deviations from them should not cause errors in estimates. Given this clarification, we further explore the potential for using information at multiple frequencies to augment the information derived from time series of temperature.

Osmotic potential calculations of inorganic and organic aqueous solutions over wide solute concentration levels and temperatures

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

Cochrane, T. T., E-mail: agteca@hotmail.com; Cochrane, T. A., E-mail: tom.cochrane@canterbury.ac.nz

Purpose: To demonstrate that the authors’ new “aqueous solution vs pure water” equation to calculate osmotic potential may be used to calculate the osmotic potentials of inorganic and organic aqueous solutions over wide ranges of solute concentrations and temperatures. Currently, the osmotic potentials of solutions used for medical purposes are calculated from equations based on the thermodynamics of the gas laws which are only accurate at low temperature and solute concentration levels. Some solutions used in medicine may need their osmotic potentials calculated more accurately to take into account solute concentrations and temperatures. Methods: The authors experimented with their newmore » equation for calculating the osmotic potentials of inorganic and organic aqueous solutions up to and beyond body temperatures by adjusting three of its factors; (a) the volume property of pure water, (b) the number of “free” water molecules per unit volume of solution, “N{sub f},” and (c) the “t” factor expressing the cooperative structural relaxation time of pure water at given temperatures. Adequate information on the volume property of pure water at different temperatures is available in the literature. However, as little information on the relative densities of inorganic and organic solutions, respectively, at varying temperatures needed to calculate N{sub f} was available, provisional equations were formulated to approximate values. Those values together with tentative t values for different temperatures chosen from values calculated by different workers were substituted into the authors’ equation to demonstrate how osmotic potentials could be estimated over temperatures up to and beyond bodily temperatures. Results: The provisional equations formulated to calculate N{sub f}, the number of free water molecules per unit volume of inorganic and organic solute solutions, respectively, over wide concentration ranges compared well with the calculations of N{sub f} using recorded relative density data at 20 °C. They were subsequently used to estimate N{sub f} values at temperatures up to and excess of body temperatures. Those values, together with t values at temperatures up to and in excess of body temperatures recorded in the literature, were substituted in the authors’ equation for the provisional calculation of osmotic potentials. The calculations indicated that solution temperatures and solute concentrations have a marked effect on osmotic potentials. Conclusions: Following work to measure the relative densities of aqueous solutions for the calculation of N{sub f} values and the determination of definitive t values up to and beyond bodily temperatures, the authors’ equation would enable the accurate estimations of the osmotic potentials of wide concentrations of aqueous solutions of inorganic and organic solutes over the temperature range. The study illustrates that not only solute concentrations but also temperatures have a marked effect on osmotic potentials, an observation of medical and biological significance.« less

Time Dependent Solution for the He I Line Ratio Electron Temperature and Density Diagnostic in TEXTOR and DIII-D

NASA Astrophysics Data System (ADS)

Munoz Burgos, J. M.; Schmitz, O.; Unterberg, E. A.; Loch, S. D.; Balance, C. P.

2010-11-01

We developed a time dependent solution for the He I line ratio diagnostic. Stationary solution is applied for L-mode at TEXTOR. The radial range is typically limited to a region near the separatrix due to metastable effects, and the atomic data used. We overcome this problem by applying a time dependent solution and thus avoid unphysical results. We use a new R-Matrix with Pseudostates and Convergence Cross-Coupling electron impact excitation and ionization atomic data set into the Collisional Radiative Model (CRM). We include contributions from higher Rydberg states into the CRM by means of the projection matrix. By applying this solution (to the region near the wall) and the stationary solution (near the separatrix), we triple the radial range of the current diagnostic. We explore the possibility of extending this approach to H-mode plasmas in DIII-D by estimating line emission profiles from electron temperature and density Thomson scattering data.

Dielectric Interactions and the Prediction of Retention Times of Pesticides in Supercritical Fluid Chromatography with CO2

NASA Astrophysics Data System (ADS)

Alvarez, Guillermo A.; Baumanna, Wolfram

2005-02-01

A thermodynamic model for the partition of a solute (pesticide) between two immiscible phases, such as the stationary and mobile phases of supercritical fluid chromatography with CO2, is developed from first principles. A key ingredient of the model is the result of the calculation made by Liptay of the energy of interaction of a polar molecule with a dielectric continuum, which represents the solvent. The strength of the interaction between the solute and the solvent, which may be considered a measure of the solvent power, is characterized by a function g = (ɛ - 1)/(2ɛ +1), where ɛ is the dielectric constant of the medium, which is a function of the temperature T and the pressure P. Since the interactions between the nonpolar supercritical CO2 solvent and the slightly polar pesticide molecules are considered to be extremely weak, a regular solution model is appropriate from the thermodynamic point of view. At constant temperature, the model predicts a linear dependence of the logarithm of the capacity factor (lnk) of the chromatographic experiment on the function g = g(P), as the pressure is varied, with a slope which depends on the dipole moment of the solute, dispersion interactions and the size of the solute cavity in the solvent. At constant pressure, once the term containing the g (solvent interaction) factor is subtracted from lnk, a plot of the resulting term against the inverse of temperature yields the enthalpy change of transfer of the solute from the mobile (supercritical CO2) phase to the stationary (adsorbent) phase. The increase in temperature with the consequent large volume expansion of the supercritical fluid lowers its solvent strength and hence the capacity factor of the column (or solute retention time) increases. These pressure and temperature effects, predicted by the model, agree excellently with the experimental retention times of seven pesticides. Beyond a temperature of about 393 K, where the liquid solvent densities approach those of a gas (and hence the solvent strength becomes negligible), a dramatic loss of the retention times of all pesticides is observed in the experiments; this is attributed to desorption of the solute from the stationary phase, as predicted by Le Châtelier's principle for the (exothermic) adsorption process.

Optical and Transport Properties of Energetic Materials

NASA Astrophysics Data System (ADS)

Choi, Chang Sun

1990-01-01

The densities of Hydroxyl ammonium nitrate (HAN) based fast reacting liquids were measured as a function of pressure (up to 4.83 kbars) at several temperatures and the results of density measurements were fit to the Tait equation. Also the shear viscosities of this liquid were measured as a function of both pressure and temperature. The free volume model was applied to explain behavior of the shear viscosity with the assumption that only the reference temperature (T_0) in the Fulcher (1925), WLF (Williams, Landel, and Ferry) and Angell equations depends on pressure. The general relation to predict viscosity of this liquid at any temperature and pressure was derived and the difference between expected and measured values are about 5%. The phase diagrams of the HAN solution, Triethanol ammonium nitrate (TEAN) solution and LP-1845 were obtained through Differential Scanning Calorimetry (DSC) measurements. The TEAN solution has a eutectic temperature in the vicinity of 260^circK. The measured phase diagrams are in good agreement with the calculated phase diagrams. The TEAN solutions show a large supercooling effect. Some phase separation was observed in the TEAN solutions and this separation was believed to be due to eutectic composition of the TEAN solution. The expected freezing temperature of LP-1845 was almost the same with the calculated T_0 from the viscosity data. Raman spectra from the HAN solution, TEAN solution and LP-1845 were measured. Every peak in the spectra was assigned. These solutions show various interactions, such as ion-ion pairing and ion-water interaction. The strongest peak was a NO_3^- symmetric stretch mode at 1050 cm^{-1}. The time correlation functions were calculated from the Raman spectra of the 1050 cm^{-1} peak. The correlation time, which can be calculated from the linewidth, become shorter with decreasing temperatures and with increasing concentrations. The Kubo's stochastic theory explains the correlation functions very well if the solution is relatively dilute. The pressure dependence of the reaction rate was estimated by using the density data and Raman peak shift data.

Thermal effect of climate change on groundwater-fed ecosystems

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

Burns, Erick R.; Zhu, Yonghui; Zhan, Hongbin

Groundwater temperature changes will lag surface temperature changes from a changing climate. Steady state solutions of the heat-transport equations are used to identify key processes that control the long-term thermal response of springs and other groundwater discharge to climate change, in particular changes in (1) groundwater recharge rate and temperature and (2) land-surface temperature transmitted through the vadose zone. Transient solutions are developed to estimate the time required for new thermal signals to arrive at ecosystems. The solution is applied to the volcanic Medicine Lake highlands, California, USA, and associated springs complexes that host groundwater-dependent ecosystems. In this system, uppermore » basin groundwater temperatures are strongly affected only by recharge conditions. However, as the vadose zone thins away from the highlands, changes in the average annual land-surface temperature also influence groundwater temperatures. Transient response to temperature change depends on both the conductive time scale and the rate at which recharge delivers heat. Most of the thermal response of groundwater at high elevations will occur within 20 years of a shift in recharge temperatures, but the large lower elevation springs will respond more slowly, with about half of the conductive response occurring within the first 20 years and about half of the advective response to higher recharge temperatures occurring in approximately 60 years.« less

Thermal effect of climate change on groundwater-fed ecosystems

DOE PAGES

Burns, Erick R.; Zhu, Yonghui; Zhan, Hongbin; ...

2017-04-24

Groundwater temperature changes will lag surface temperature changes from a changing climate. Steady state solutions of the heat-transport equations are used to identify key processes that control the long-term thermal response of springs and other groundwater discharge to climate change, in particular changes in (1) groundwater recharge rate and temperature and (2) land-surface temperature transmitted through the vadose zone. Transient solutions are developed to estimate the time required for new thermal signals to arrive at ecosystems. The solution is applied to the volcanic Medicine Lake highlands, California, USA, and associated springs complexes that host groundwater-dependent ecosystems. In this system, uppermore » basin groundwater temperatures are strongly affected only by recharge conditions. However, as the vadose zone thins away from the highlands, changes in the average annual land-surface temperature also influence groundwater temperatures. Transient response to temperature change depends on both the conductive time scale and the rate at which recharge delivers heat. Most of the thermal response of groundwater at high elevations will occur within 20 years of a shift in recharge temperatures, but the large lower elevation springs will respond more slowly, with about half of the conductive response occurring within the first 20 years and about half of the advective response to higher recharge temperatures occurring in approximately 60 years.« less

Thermal effect of climate change on groundwater-fed ecosystems

NASA Astrophysics Data System (ADS)

Burns, Erick R.; Zhu, Yonghui; Zhan, Hongbin; Manga, Michael; Williams, Colin F.; Ingebritsen, Steven E.; Dunham, Jason B.

2017-04-01

Groundwater temperature changes will lag surface temperature changes from a changing climate. Steady state solutions of the heat-transport equations are used to identify key processes that control the long-term thermal response of springs and other groundwater discharge to climate change, in particular changes in (1) groundwater recharge rate and temperature and (2) land-surface temperature transmitted through the vadose zone. Transient solutions are developed to estimate the time required for new thermal signals to arrive at ecosystems. The solution is applied to the volcanic Medicine Lake highlands, California, USA, and associated springs complexes that host groundwater-dependent ecosystems. In this system, upper basin groundwater temperatures are strongly affected only by recharge conditions. However, as the vadose zone thins away from the highlands, changes in the average annual land-surface temperature also influence groundwater temperatures. Transient response to temperature change depends on both the conductive time scale and the rate at which recharge delivers heat. Most of the thermal response of groundwater at high elevations will occur within 20 years of a shift in recharge temperatures, but the large lower elevation springs will respond more slowly, with about half of the conductive response occurring within the first 20 years and about half of the advective response to higher recharge temperatures occurring in approximately 60 years.

Thermal effect of climate change on groundwater-fed ecosystems

USGS Publications Warehouse

Burns, Erick; Zhu, Yonghui; Zhan, Hongbin; Manga, Michael; Williams, Colin F.; Ingebritsen, Steven E.; Dunham, Jason B.

2017-01-01

Groundwater temperature changes will lag surface temperature changes from a changing climate. Steady state solutions of the heat-transport equations are used to identify key processes that control the long-term thermal response of springs and other groundwater discharge to climate change, in particular changes in (1) groundwater recharge rate and temperature and (2) land-surface temperature transmitted through the vadose zone. Transient solutions are developed to estimate the time required for new thermal signals to arrive at ecosystems. The solution is applied to the volcanic Medicine Lake highlands, California, USA, and associated springs complexes that host groundwater-dependent ecosystems. In this system, upper basin groundwater temperatures are strongly affected only by recharge conditions. However, as the vadose zone thins away from the highlands, changes in the average annual land-surface temperature also influence groundwater temperatures. Transient response to temperature change depends on both the conductive time scale and the rate at which recharge delivers heat. Most of the thermal response of groundwater at high elevations will occur within 20 years of a shift in recharge temperatures, but the large lower elevation springs will respond more slowly, with about half of the conductive response occurring within the first 20 years and about half of the advective response to higher recharge temperatures occurring in approximately 60 years.

Natural convection heat transfer in an oscillating vertical cylinder

PubMed Central

Ali Shah, Nehad; Tassaddiq, Asifa; Mustapha, Norzieha; Kechil, Seripah Awang

2018-01-01

This paper studies the heat transfer analysis caused due to free convection in a vertically oscillating cylinder. Exact solutions are determined by applying the Laplace and finite Hankel transforms. Expressions for temperature distribution and velocity field corresponding to cosine and sine oscillations are obtained. The solutions that have been obtained for velocity are presented in the forms of transient and post-transient solutions. Moreover, these solutions satisfy both the governing differential equation and all imposed initial and boundary conditions. Numerical computations and graphical illustrations are used in order to study the effects of Prandtl and Grashof numbers on velocity and temperature for various times. The transient solutions for both cosine and sine oscillations are also computed in tables. It is found that, the transient solutions are of considerable interest up to the times t = 15 for cosine oscillations and t = 1.75 for sine oscillations. After these moments, the transient solutions can be neglected and, the fluid moves according with the post-transient solutions. PMID:29304161

Natural convection heat transfer in an oscillating vertical cylinder.

PubMed

Khan, Ilyas; Ali Shah, Nehad; Tassaddiq, Asifa; Mustapha, Norzieha; Kechil, Seripah Awang

2018-01-01

This paper studies the heat transfer analysis caused due to free convection in a vertically oscillating cylinder. Exact solutions are determined by applying the Laplace and finite Hankel transforms. Expressions for temperature distribution and velocity field corresponding to cosine and sine oscillations are obtained. The solutions that have been obtained for velocity are presented in the forms of transient and post-transient solutions. Moreover, these solutions satisfy both the governing differential equation and all imposed initial and boundary conditions. Numerical computations and graphical illustrations are used in order to study the effects of Prandtl and Grashof numbers on velocity and temperature for various times. The transient solutions for both cosine and sine oscillations are also computed in tables. It is found that, the transient solutions are of considerable interest up to the times t = 15 for cosine oscillations and t = 1.75 for sine oscillations. After these moments, the transient solutions can be neglected and, the fluid moves according with the post-transient solutions.

An Inexpensive Solution Calorimeter

ERIC Educational Resources Information Center

Kavanagh, Emma; Mindel, Sam; Robertson, Giles; Hughes, D. E. Peter

2008-01-01

We describe the construction of a simple solution calorimeter, using a miniature bead thermistor as a temperature-sensing element. This has a response time of a few seconds and made it possible to carry out a thermometric reaction in under a minute, which led to minimal heat losses. Small temperature changes of 1 K associated with enthalpies of…

A Green's function approach for assessing the thermal disturbance caused by drilling deep boreholes in rock or ice

USGS Publications Warehouse

Clow, Gary D.

2015-01-01

A knowledge of subsurface temperatures in sedimentary basins, fault zones, volcanic environments and polar ice sheets is of interest for a wide variety of geophysical applications. However, the process of drilling deep boreholes in these environments to provide access for temperature and other measurements invariably disturbs the temperature field around a newly created borehole. Although this disturbance dissipates over time, most temperature measurements are made while the temperature field is still disturbed. Thus, the measurements must be ‘corrected’ for the drilling-disturbance effect if the undisturbed temperature field is to be determined. This paper provides compact analytical solutions for the thermal drilling disturbance based on 1-D (radial) and 2-D (radial and depth) Green's functions (GFs) in cylindrical coordinates. Solutions are developed for three types of boundary conditions (BCs) at the borehole wall: (1) prescribed temperature, (2) prescribed heat flux and (3) a prescribed convective condition. The BC at the borehole wall is allowed to vary both with depth and time. Inclusion of the depth dimension in the 2-D solution allows vertical heat-transfer effects to be quantified in situations where they are potentially important, that is, near the earth's surface, at the bottom of a well and when considering finite-drilling rates. The 2-D solution also includes a radial- and time-dependent BC at the earth's surface to assess the impact of drilling-related infrastructure (drilling pads, mud pits, permanent shelters) on the subsurface temperature field. Latent-heat effects due to the melting and subsequent refreezing of interstitial ice while drilling a borehole through ice-rich permafrost can be included in the GF solution as a moving-plane heat source (or sink) located at the solid–liquid interface. Synthetic examples are provided illustrating the 1-D and 2-D GF solutions. The flexibility of the approach allows the investigation of thermal drilling effects in rock or ice for a wide variety of drilling technologies. Numerical values for the required radial GFs GR are available through the Advanced Cooperative Arctic Data and Information Service at doi:10.5065/D64F1NS6.

Properties of two-temperature dissipative accretion flow around black holes

NASA Astrophysics Data System (ADS)

Dihingia, Indu K.; Das, Santabrata; Mandal, Samir

2018-04-01

We study the properties of two-temperature accretion flow around a non-rotating black hole in presence of various dissipative processes where pseudo-Newtonian potential is adopted to mimic the effect of general relativity. The flow encounters energy loss by means of radiative processes acted on the electrons and at the same time, flow heats up as a consequence of viscous heating effective on ions. We assumed that the flow is exposed with the stochastic magnetic fields that leads to Synchrotron emission of electrons and these emissions are further strengthen by Compton scattering. We obtain the two-temperature global accretion solutions in terms of dissipation parameters, namely, viscosity (α) and accretion rate ({\\dot{m}}), and find for the first time in the literature that such solutions may contain standing shock waves. Solutions of this kind are multitransonic in nature, as they simultaneously pass through both inner critical point (xin) and outer critical point (xout) before crossing the black hole horizon. We calculate the properties of shock-induced global accretion solutions in terms of the flow parameters. We further show that two-temperature shocked accretion flow is not a discrete solution, instead such solution exists for wide range of flow parameters. We identify the effective domain of the parameter space for standing shock and observe that parameter space shrinks as the dissipation is increased. Since the post-shock region is hotter due to the effect of shock compression, it naturally emits hard X-rays, and therefore, the two-temperature shocked accretion solution has the potential to explain the spectral properties of the black hole sources.

Physical and chemical stability of proflavine contrast agent solutions for early detection of oral cancer.

PubMed

Kawedia, Jitesh D; Zhang, Yan-Ping; Myers, Alan L; Richards-Kortum, Rebecca R; Kramer, Mark A; Gillenwater, Ann M; Culotta, Kirk S

2016-02-01

Proflavine hemisulfate solution is a fluorescence contrast agent to visualize cell nuclei using high-resolution optical imaging devices such as the high-resolution microendoscope. These devices provide real-time imaging to distinguish between normal versus neoplastic tissue. These images could be helpful for early screening of oral cancer and its precursors and to determine accurate margins of malignant tissue for ablative surgery. Extemporaneous preparation of proflavine solution for these diagnostic procedures requires preparation in batches and long-term storage to improve compounding efficiency in the pharmacy. However, there is a paucity of long-term stability data for proflavine contrast solutions. The physical and chemical stability of 0.01% (10 mg/100 ml) proflavine hemisulfate solutions prepared in sterile water was determined following storage at refrigeration (4-8℃) and room temperature (23℃). Concentrations of proflavine were measured at predetermined time points up to 12 months using a validated stability-indicating high-performance liquid chromatography method. Proflavine solutions stored under refrigeration were physically and chemically stable for at least 12 months with concentrations ranging from 95% to 105% compared to initial concentration. However, in solutions stored at room temperature increased turbidity and particulates were observed in some of the tested vials at 9 months and 12 months with peak particle count reaching 17-fold increase compared to baseline. Solutions stored at room temperature were chemically stable up to six months (94-105%). Proflavine solutions at concentration of 0.01% were chemically and physically stable for at least 12 months under refrigeration. The solution was chemically stable for six months when stored at room temperature. We recommend long-term storage of proflavine solutions under refrigeration prior to diagnostic procedure. © The Author(s) 2014.

Thirty Stage Annular Centrifugal Contactor Thermal Profile Measurements

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

David H. Meikrantz; Troy G. Garn; Jack D. Law

2010-02-01

A thirty stage 5 cm annular centrifugal contactor cascade has been assembled and tested to obtain thermal profiles during both ambient and heated input conditions of operation. Thermocouples were installed on every stage as well as feed inputs and Real-time data was taken during experiments lasting from two to eight hours at total flow rates of 0.5 to 1.4 liters per minute. Ambient temperature profile results show that only a small amount of heat is generated by the mechanical energy of the contactors. Steady state temperature profiles mimic the ambient temperature of the lab but are higher toward the middlemore » of the cascade. Heated inlet solutions gave temperature profiles with smaller temperature gradients, more driven by the temperature of the inlet solutions than ambient lab temperature. Temperature effects of solution mixing, even at rotor speeds of 4000 rpm, were not measurable.« less

Lactated Ringer-based storage solutions are equally well suited for the storage of fresh osteochondral allografts as cell culture medium-based storage solutions.

PubMed

Harb, Afif; von Horn, Alexander; Gocalek, Kornelia; Schäck, Luisa Marilena; Clausen, Jan; Krettek, Christian; Noack, Sandra; Neunaber, Claudia

2017-07-01

Due to the rising interest in Europe to treat large cartilage defects with osteochondrale allografts, research aims to find a suitable solution for long-term storage of osteochondral allografts. This is further encouraged by the fact that legal restrictions currently limit the use of the ingredients from animal or human sources that are being used in other regions of the world (e.g. in the USA). Therefore, the aim of this study was A) to analyze if a Lactated Ringer (LR) based solution is as efficient as a Dulbecco modified Eagle's minimal essential medium (DMEM) in maintaining chondrocyte viability and B) at which storage temperature (4°C vs. 37°C) chondrocyte survival of the osteochondral allograft is optimally sustained. 300 cartilage grafts were collected from knees of ten one year-old Black Head German Sheep. The grafts were stored in four different storage solutions (one of them DMEM-based, the other three based on Lactated Ringer Solution), at two different temperatures (4 and 37°C) for 14 and 56days. At both points in time, chondrocyte survival as well as death rate, Glycosaminoglycan (GAG) content, and Hydroxyproline (HP) concentration were measured and compared between the grafts stored in the different solutions and at the different temperatures. Independent of the storage solutions tested, chondrocyte survival rates were higher when stored at 4°C compared to storage at 37°C both after short-term (14days) and long-term storage (56days). At no point in time did the DMEM-based solution show a superior chondrocyte survival compared to lactated Ringer based solution. GAG and HP content were comparable across all time points, temperatures and solutions. LR based solutions that contain only substances that are approved in Germany may be just as efficient for storing grafts as the USA DMEM-based solution gold standard. Moreover, in the present experiment storage of osteochondral allografts at 4°C was superior to storage at 37°C. Copyright © 2017 Elsevier Ltd. All rights reserved.

Preparation of Platinum (Pt) Counter Electrode Coated by Electrochemical Technique at High Temperature for Dye-sensitized Solar Cell (DSSC) Application

NASA Astrophysics Data System (ADS)

Ponken, Tanachai; Tagsin, Kamonlapron; Suwannakhun, Chuleerat; Luecha, Jakkrit; Choawunklang, Wijit

2017-09-01

Pt counter electrode was coated by electrochemical method. Electrolyte solution was synthesized by platinum (IV) choloride (PtCl4) powder dissolved in hydrochloric acid solution. Pt films were deposited on the FTO substrate. Deposition time of 10, 30 and 60 minutes, the coating current of 5, 10, 15 and 20 mA and electrolyte solution temperatures for Pt layer synthesis of 25, 30 and 40°C were varied. Surface morphology and optical properties was analyzed by digital microscopic and UV-vis spectrophotometer. Pt films exhibit uniform surface area highly for all the conditions of coating current in the deposition time of 30 and 40 minutes at 40°C. Transmittance values of Pt films deposited on FTO substrate has approximately of 5 to 50 % show that occur high reflection corresponding to dye molecule absorption increases. DSSC device was fabricated from the TiO2 standard and immersed in dye N719 for 24 hours. Efficiency was measured by solar simulator. Efficiency value obtains as high as 5.91 % for the coating current, deposition time and solution temperature of 15 mA, 30 minutes and 40°C. Summary, influence of temperature effects efficiency increasing. Pt counter electrode can be prepared easily and the suitable usefully for DSSC.

[The Influence of Different Ionic Concentration in Cell Physiological Solution on Temperature Measurement by Near Infrared].

PubMed

Zheng, Yu; Chen, Xiong; Zhou, Mei; Wang, Meng-jun; Wang, Jin-hai; Li, Gang; Cui, Jun

2015-10-01

It is important to real-timely monitor and control the temperature of cell physiological solution in patch clamp experiments, which can eliminate the uncertainty due to temperature and improve the measurement accuracy. This paper studies the influence of different ions at different concentrations in the physiological solution on precision of a temperature model by using near infrared spectroscopy and chemometrics method. Firstly, we prepared twelve sample solutions respectively with the solutes of CaCl2, KCl and NaCl at four kinds of concentrations, and collected the spectra of different solutions at the setting temperature range 20-40 degrees C, the range of the spectra is 9 615-5 714 cm(-1). Then we divided the spectra of each solution at different temperatures into two parts (a training set and a prediction set) by three methods. Interval partial least squares method was used to select an effective wavelength range and develop calibration models between the spectra in the selected range and temperature velues. The experimental results show that RMSEP of CaCl2 solution with 0.25 g x mL(-1) is maximum, the result of the three tests are 0.386 3, 0.303 7 and 0.337 2 degrees C, RMSEP of NaCl with 0.005 g x mL(-1) solution is minimum, the result of the three tests are 0.220 8, 0.155 3 and 0.145 2 degrees C. The experimental results indicate that Ca2+ has the greatest influence on the accuracy of the temperature model of the cell physiological solution, then K+, and Na+ has the least influence. And with the ionic concentration increasing, the model accuracy decreases. Therefore; when we build the temperature model of cell physiological solution, it is necessary to change the proportion of the three kinds of main ions in cell physiological solution reasonably in order to correct the effects of different ionic concentrations in physiological solution and improve the accuracy of temperature measurements by near infrared spectroscopy.

Amorphous Inorganic Electron-Selective Layers for Efficient Perovskite Solar Cells: Feasible Strategy Towards Room-Temperature Fabrication.

PubMed

Wang, Kai; Shi, Yantao; Li, Bo; Zhao, Liang; Wang, Wei; Wang, Xiangyuan; Bai, Xiaogong; Wang, Shufeng; Hao, Ce; Ma, Tingli

2016-03-02

Inorganic electron-selective layers (ESLs) are fabricated at extremely low temperatures of 70°C or even 25°C by a simple solution route. This is of great significance because the attained PCEs confirm the feasibility of room-temperature coating of inorganic amorphous ESLs through a solution method for the first time. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and characterization of LTA nanozeolite using barley husk silica: Mercury removal from standard and real solutions

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

Azizi, Seyed Naser, E-mail: azizi@umz.ac.ir; Dehnavi, Ahmad Roozbehani, E-mail: Roozbehanisulfur@yahoo.com; Joorabdoozha, Amir

2013-05-15

Highlights: ► Silica extraction from barley husk with high purity for the synthesis of A nanozeolite. ► Free template A nanozeolite synthesized via new source of silica at low temperature. ► Optimization of SiO{sub 2}/Al{sub 2}O{sub 3}, Na{sub 2}O/SiO{sub 2} ratios, temperature and time of the synthesis. ► Utilizing of synthesized A nanozeolite for mercury removal from aqueous solutions. ► Mercury removal at optimized pH, contact time and adsorbent dose from real solution. - Abstract: In this study, synthesized Lined Type A (LTA) nanozeolite from barley husk silica (BHS) was used for mercury removal from standard and real aqueous solutions.more » The BHS in amorphous phase with 80% purity was extracted from barley husk ash (BHA), and used effectively as a new source of silica for the synthesis of NaA nanozeolite. The NaA nanocrystal in pure phase has been synthesized at low temperature, without adding any organic additives. The effects of heating time, reaction temperature, SiO{sub 2}/Al{sub 2}O{sub 3}, and Na{sub 2}O/SiO{sub 2} mole ratios on the crystallization of NaA nanozeolite were studied. The adsorption capacity of mercury (II) was studied as a function of pH, contact time, and amount of adsorbent. The crystallization of NaA nanozeolite from BHS was characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), Brunauer–Emmett–Teller (BET), and FTIR techniques. Moreover, concentration of Hg{sup 2+} ions in the aqueous solutions was analyzed by hydride generation atomic absorption spectroscopy method (HG-AAS). The standard and real samples analysis showed that NaA nanozeolite is capable of Hg{sup 2+} ions removal from the aqueous solutions. Efficiency of mercury (II) adsorption from real solutions onto the nano-sized NaA zeolite was 98%.« less

[Antimicrobial Effects of Iodine-Polyvinyl Alcohol Ophthalmic and Eye Washing Solution (PA * IODO) with Special Reference to its Temperature, Concentration and Time and its Preservation Stability].

PubMed

Hatano, Hiroshi; Sakamoto, Masako; Hayashi, Kazuo; Kamiya, Seigo

2015-08-01

Temperature, concentration and time are the three factors that affect the inactivation capacity of iodine antiseptics. We investigated the effect of these factors on the microbe inactivation of Iodine-Polyvinyl Alcohol ophthalmic and eye washing solution (PA * IODO), and also investigated the preservation conditions on stability of the inactivation activity of the PA * IODO. Test microbes were mixed with PA * IODO, varying the three factors. The live microbes were counted after each reaction. The effects of plugging and preservation temperature were investigated to determine the preserving stability. The inactivation capacity of PA * IODO tended to decrease in almost all microbes tested at 4 degrees C. Twenty times or less diluted PA * IODO killed almost all microbes completely. The time effect was more marked in viruses. Plugging and low-temperature made iodine concentration in diluted PA * IODO remain relatively high. The concentration of PA * IODO affected the inactivation ability more than the temperature and time, although all the three factors correlated positively to the inactivation. For preservation the diluted PA * IODO needed plugging and low temperature.

The inverse Numerical Computer Program FLUX-BOT for estimating Vertical Water Fluxes from Temperature Time-Series.

NASA Astrophysics Data System (ADS)

Trauth, N.; Schmidt, C.; Munz, M.

2016-12-01

Heat as a natural tracer to quantify water fluxes between groundwater and surface water has evolved to a standard hydrological method. Typically, time series of temperatures in the surface water and in the sediment are observed and are subsequently evaluated by a vertical 1D representation of heat transport by advection and dispersion. Several analytical solutions as well as their implementation into user-friendly software exist in order to estimate water fluxes from the observed temperatures. Analytical solutions can be easily implemented but assumptions on the boundary conditions have to be made a priori, e.g. sinusoidal upper temperature boundary. Numerical models offer more flexibility and can handle temperature data which is characterized by irregular variations such as storm-event induced temperature changes and thus cannot readily be incorporated in analytical solutions. This also reduced the effort of data preprocessing such as the extraction of the diurnal temperature variation. We developed a software to estimate water FLUXes Based On Temperatures- FLUX-BOT. FLUX-BOT is a numerical code written in MATLAB which is intended to calculate vertical water fluxes in saturated sediments, based on the inversion of measured temperature time series observed at multiple depths. It applies a cell-centered Crank-Nicolson implicit finite difference scheme to solve the one-dimensional heat advection-conduction equation. Besides its core inverse numerical routines, FLUX-BOT includes functions visualizing the results and functions for performing uncertainty analysis. We provide applications of FLUX-BOT to generic as well as to measured temperature data to demonstrate its performance.

Modeling the Quiet Time Outflow Solution in the Polar Cap

NASA Technical Reports Server (NTRS)

Glocer, Alex

2011-01-01

We use the Polar Wind Outflow Model (PWOM) to study the geomagnetically quiet conditions in the polar cap during solar maximum, The PWOM solves the gyrotropic transport equations for O(+), H(+), and He(+) along several magnetic field lines in the polar region in order to reconstruct the full 3D solution. We directly compare our simulation results to the data based empirical model of Kitamura et al. [2011] of electron density, which is based on 63 months of Akebono satellite observations. The modeled ion and electron temperatures are also compared with a statistical compilation of quiet time data obtained by the EISCAT Svalbard Radar (ESR) and Intercosmos Satellites (Kitamura et al. [2011]). The data and model agree reasonably well. This study shows that photoelectrons play an important role in explaining the differences between sunlit and dark results, ion composition, as well as ion and electron temperatures of the quiet time polar wind solution. Moreover, these results provide validation of the PWOM's ability to model the quiet time ((background" solution.

Effects of Temperature and Method of Solution Preparation on the Performance of a Typical Red Mud Flocculent

NASA Astrophysics Data System (ADS)

Ferland, Pierre; Malito, John T.; Phillips, Everett C.

Alcan International Ltd. in collaboration with Ondeo Nalco Company have carried out a fundamental study on the dissolution and performance of a 100% anionic polymer. The effects of method of preparation, solvent composition, temperature and exposure time on flocculent activity under conditions relevant to both atmospheric and pressure decantation were investigated. Flocculent activity was determined using static and dynamic settling tests, and the results were correlated with the reduced specific viscosity (RSV). For any given method of preparation of the flocculent solutions (makeup/dilution) the RSV tended to decrease with increasing solution ionic strength, independent of ionic speciation. While a significant loss in flocculent activity occurred with long exposure of the solution to high temperature, only a minor loss occurred in the short time required to flocculate and settle the mud in a decanter operating at 150 °C. Recent results in an actual plant pressure decanter appear to validate this conclusion.

Measurement of the Water Relaxation Time of ɛ-Polylysine Aqueous Solutions

NASA Astrophysics Data System (ADS)

Shirakashi, Ryo; Amano, Yuki; Yamada, Jun

2017-05-01

ɛ-Polylysine is an effective food preservative. In this paper, the β-relaxation time of ɛ-polylysine aqueous solutions, which represents the rotational speed of a single water molecule, was measured by broadband dielectric spectroscopy at various temperatures and concentrations. The broadband dielectric spectrum of each sample containing water ranging from 35 wt% to 75 wt% at temperatures ranging from 0°C to 25°C was measured using a co-axial semirigid cable probe. The measured dielectric spectra of the samples were composed of several Debye relaxation peaks, including a shortest single molecular rotational relaxation time of water, the β-relaxation time, longer than that of pure water. This result represents that ɛ-polylysine suppresses the molecular kinetics of water. It is also found that the β-relaxation time of an ɛ-polylysine solution that contained more than 35 wt% water showed a typical Arrhenius plot in the temperature range from 0°C to 25°C. The activation energy of each sample depends on the water content ratio of the sample. As indicated by its long β-relaxation time, ɛ-polylysine is expected to possess high abilities of suppressing freezing and ice coarsening.

Do We Really Need Sinusoidal Surface Temperatures to Apply Heat Tracing Techniques to Estimate Streambed Fluid Fluxes?

NASA Astrophysics Data System (ADS)

Luce, C. H.; Tonina, D.; Applebee, R.; DeWeese, T.

2017-12-01

Two common refrains about using the one-dimensional advection diffusion equation to estimate fluid fluxes, thermal conductivity, or bed surface elevation from temperature time series in streambeds are that the solution assumes that 1) the surface boundary condition is a sine wave or nearly so, and 2) there is no gradient in mean temperature with depth. Concerns on these subjects are phrased in various ways, including non-stationarity in frequency, amplitude, or phase. Although the mathematical posing of the original solution to the problem might lead one to believe these constraints exist, the perception that they are a source of error is a fallacy. Here we re-derive the inverse solution of the 1-D advection-diffusion equation starting with an arbitrary surface boundary condition for temperature. In doing so, we demonstrate the frequency-independence of the solution, meaning any single frequency can be used in the frequency-domain solutions to estimate thermal diffusivity and 1-D fluid flux in streambeds, even if the forcing has multiple frequencies. This means that diurnal variations with asymmetric shapes, gradients in the mean temperature with depth, or `non-stationary' amplitude and frequency (or phase) do not actually represent violations of assumptions, and they should not cause errors in estimates when using one of the suite of existing solution methods derived based on a single frequency. Misattribution of errors to these issues constrains progress on solving real sources of error. Numerical and physical experiments are used to verify this conclusion and consider the utility of information at `non-standard' frequencies and multiple frequencies to augment the information derived from time series of temperature.

Co and Fe-catalysts supported on sepiolite: effects of preparation conditions on their catalytic behaviors in high temperature gas flow treatment of dye.

PubMed

Lin, Xiangfeng; Fang, Jian; Chen, Menglin; Huang, Zhi; Su, Chengyuan

2016-08-01

An efficient adsorbent/catalyst Co and Fe-catalysts loaded on sepiolite (Co-Fe/sepiolite) was successfully prepared for high temperature gas flow catalytic reaction by a simple impregnation method. The impact of preparation conditions (such as pH value of impregnation solution, impregnation time, calcination temperature, and time) on catalytic activity was studied. We found that the catalytic activity of Co-Fe/sepiolite was strongly influenced by all the investigated parameters. The regeneration efficiency (RE) was used to evaluate the catalytic activity. The RE is more noticeable at pH 5.0 of impregnation solution, impregnation time 18 h, calcination temperature 650 °C, and calcination time 3 h. This Co-Fe/sepiolite has great adsorption capacity in absorbing dye. It is used for an adsorbent to adsorb dye from wastewater solution under dynamic adsorption and saturated with dye, then regenerated with high temperature gas flow for adsorption/oxidation cycles. The Co-Fe/sepiolite acts as a catalyst to degrade the dye during regeneration under high temperature gas flow. Hence, the Co-Fe/sepiolite is not only an adsorbent but also a catalyst. The Co-Fe/sepiolite is more stable than sepiolite when applied in the treatment of plant's wastewater. The Co-Fe/sepiolite can be reused in adsorption-regeneration cycle. The results indicate the usability of the proposed combined process, dye adsorption on Co-Fe/sepiolite followed by the catalytic oxidation in high temperature gas flow.

Time-asymptotic solutions of the Navier-Stokes equation for free shear flows using an alternating-direction implicit method

NASA Technical Reports Server (NTRS)

Rudy, D. H.; Morris, D. J.

1976-01-01

An uncoupled time asymptotic alternating direction implicit method for solving the Navier-Stokes equations was tested on two laminar parallel mixing flows. A constant total temperature was assumed in order to eliminate the need to solve the full energy equation; consequently, static temperature was evaluated by using algebraic relationship. For the mixing of two supersonic streams at a Reynolds number of 1,000, convergent solutions were obtained for a time step 5 times the maximum allowable size for an explicit method. The solution diverged for a time step 10 times the explicit limit. Improved convergence was obtained when upwind differencing was used for convective terms. Larger time steps were not possible with either upwind differencing or the diagonally dominant scheme. Artificial viscosity was added to the continuity equation in order to eliminate divergence for the mixing of a subsonic stream with a supersonic stream at a Reynolds number of 1,000.

Structural study of aggregated β-carotene by absorption spectroscopy

NASA Astrophysics Data System (ADS)

Lu, Li Ping; Wei, Liang Shu

2017-10-01

By UV-visible absorption spectroscope, the aggregated β-carotene in hydrated ethanol was studied in the temperature range of 5 55°C, with different ethanol/water ratio. And the structural evolutions of these aggregates with time were detected. The spectrophotometric analysis showed that the aggregate of β-carotene formed in 1:1 ethanol/water solution transfered from H-type to J-type with temperature increase. In 2:1 ethanol/water solution a new type of aggregate with strong coupling was predicated by the appearing absorption peak located at about 550 nm. In the time scales of 48 houses all the aggregated structures were stable, but the absorption intensity decreased with time. It was concluded that the types of aggregated β-carotene which wouldn't change with time depended on the solvent composition and temperature.

Solutions for the diurnally forced advection-diffusion equation to estimate bulk fluid velocity and diffusivity in streambeds from temperature time series

Treesearch

Charles H. Luce; Daniele Tonina; Frank Gariglio; Ralph Applebee

2013-01-01

Work over the last decade has documented methods for estimating fluxes between streams and streambeds from time series of temperature at two depths in the streambed. We present substantial extension to the existing theory and practice of using temperature time series to estimate streambed water fluxes and thermal properties, including (1) a new explicit analytical...

Temperature dependence of water-water and ion-water correlations in bulk water and electrolyte solutions probed by femtosecond elastic second harmonic scattering

NASA Astrophysics Data System (ADS)

Chen, Yixing; Dupertuis, Nathan; Okur, Halil I.; Roke, Sylvie

2018-06-01

The temperature dependence of the femtosecond elastic second harmonic scattering (fs-ESHS) response of bulk light and heavy water and their electrolyte solutions is presented. We observe clear temperature dependent changes in the hydrogen (H)-bond network of water that show a decrease in the orientational order of water with increasing temperature. Although D2O has a more structured H-bond network (giving rise to more fs-ESHS intensity), the relative temperature dependence is larger in H2O. The changes are interpreted in terms of the symmetry of H-bonds and are indicators of nuclear quantum effects. Increasing the temperature in electrolyte solutions decreases the influence of the total electrostatic field from ions on the water-water correlations, as expected from Debye-Hückel theory, since the Debye length becomes longer. The effects are, however, 1.9 times (6.3 times) larger than those predicted for H2O (D2O). Since fs-ESHS responses can be computed from known molecular coordinates, our observations provide a unique opportunity to refine quantum mechanical models of water.

Equations for O2 and CO2 solubilities in saline and plasma: combining temperature and density dependences.

PubMed

Christmas, Kevin M; Bassingthwaighte, James B

2017-05-01

Solubilities of respiratory gasses in water, saline, and plasma decrease with rising temperatures and solute concentrations. Henry's Law, C = α·P, states that the equilibrium concentration of a dissolved gas is solubility times partial pressure. Solubilities in the water of a solution depend on temperature and the content of other solutes. Blood temperatures may differ more than 20°C between skin and heart, and an erythrocyte will undergo that range as blood circulates. The concentrations of O 2 and CO 2 are the driving forces for diffusion, exchanges, and for reactions. We provide an equation for O 2 and CO 2 solubilities, α, that allows for continuous changes in temperature, T, and solution density, ρ, in dynamically changing states:[Formula: see text]This two-exponential expression with a density scalar γ, and a density exponent β, accounts for solubility changes due to density changes of an aqueous solution. It fits experimental data on solubilities in water, saline, and plasma over temperatures from 20 to 40°C, and for plasma densities, ρ sol up to 1.020 g/ml with ~0.3% error. The amounts of additional bound O 2 (to Hb) and CO 2 (bicarbonate and carbamino) depend on the concentrations in the local water space and the reaction parameters. During exercise, solubility changes are large; both ρ sol and T change rapidly with spatial position and with time. In exercise hemoconcentration plasma, ρ sol exceeds 1.02, whereas T may range over 20°C. The six parameters for O 2 and the six for CO 2 are constants, so solubilities are calculable continuously as T and ρ sol change. NEW & NOTEWORTHY Solubilities for oxygen and carbon dioxide are dependent on the density of the solution, on temperature, and on the partial pressure. We provide a brief equation suitable for hand calculators or mathematical modeling, accounting for these factors over a wide range of temperatures and solution densities for use in rapidly changing conditions, such as extreme exercise or osmotic transients, with better than 0.5% accuracy. Copyright © 2017 the American Physiological Society.

Evaluating the time and temperature dependent biaxial strength of Gore-Select ® series 57 proton exchange membrane using a pressure loaded blister test

NASA Astrophysics Data System (ADS)

Grohs, Jacob R.; Li, Yongqiang; Dillard, David A.; Case, Scott W.; Ellis, Michael W.; Lai, Yeh-Hung; Gittleman, Craig S.

Temperature and humidity fluctuations in operating fuel cells impose significant biaxial stresses in the constrained proton exchange membranes (PEMs) of a fuel cell stack. The strength of the PEM, and its ability to withstand cyclic environment-induced stresses, plays an important role in membrane integrity and consequently, fuel cell durability. In this study, a pressure loaded blister test is used to characterize the biaxial strength of Gore-Select ® series 57 over a range of times and temperatures. Hencky's classical solution for a pressurized circular membrane is used to estimate biaxial strength values from burst pressure measurements. A hereditary integral is employed to construct the linear viscoelastic analog to Hencky's linear elastic exact solution. Biaxial strength master curves are constructed using traditional time-temperature superposition principle techniques and the associated temperature shift factors show good agreement with shift factors obtained from constitutive (stress relaxation) and fracture (knife slit) tests of the material.

An Analytical Solution for Transient Thermal Response of an Insulated Structure

NASA Technical Reports Server (NTRS)

Blosser, Max L.

2012-01-01

An analytical solution was derived for the transient response of an insulated aerospace vehicle structure subjected to a simplified heat pulse. This simplified problem approximates the thermal response of a thermal protection system of an atmospheric entry vehicle. The exact analytical solution is solely a function of two non-dimensional parameters. A simpler function of these two parameters was developed to approximate the maximum structural temperature over a wide range of parameter values. Techniques were developed to choose constant, effective properties to represent the relevant temperature and pressure-dependent properties for the insulator and structure. A technique was also developed to map a time-varying surface temperature history to an equivalent square heat pulse. Using these techniques, the maximum structural temperature rise was calculated using the analytical solutions and shown to typically agree with finite element simulations within 10 to 20 percent over the relevant range of parameters studied.

Rapid Online Non-Enzymatic Protein Digestion Analysis with High Pressure Superheated ESI-MS

NASA Astrophysics Data System (ADS)

Chen, Lee Chuin; Kinoshita, Masato; Noda, Masato; Ninomiya, Satoshi; Hiraoka, Kenzo

2015-07-01

Recently, we reported a new ESI ion source that could electrospray the super-heated aqueous solution with liquid temperature much higher than the normal boiling point ( J. Am. Soc. Mass Spectrom. 25, 1862-1869). The boiling of liquid was prevented by pressurizing the ion source to a pressure greater than atmospheric pressure. The maximum operating pressure in our previous prototype was 11 atm, and the highest achievable temperature was 180°C. In this paper, a more compact prototype that can operate up to 27 atm and 250°C liquid temperatures is constructed, and reproducible MS acquisition can be extended to electrospray temperatures that have never before been tested. Here, we apply this super-heated ESI source to the rapid online protein digestion MS. The sample solution is rapidly heated when flowing through a heated ESI capillary, and the digestion products are ionized by ESI in situ when the solution emerges from the tip of the heated capillary. With weak acid such as formic acid as solution, the thermally accelerated digestion (acid hydrolysis) has the selective cleavage at the aspartate (Asp, D) residue sites. The residence time of liquid within the active heating region is about 20 s. The online operation eliminates the need to transfer the sample from the digestion reactor, and the output of the digestive reaction can be monitored and manipulated by the solution flow rate and heater temperature in a near real-time basis.

Closed-form analytical solutions of high-temperature heat pipe startup and frozen startup limitation

NASA Technical Reports Server (NTRS)

Cao, Y.; Faghri, A.

1992-01-01

Previous numerical and experimental studies indicate that the high-temperature heat pipe startup process is characterized by a moving hot zone with relatively sharp fronts. Based on the above observation, a flat-front model for an approximate analytical solution is proposed. A closed-form solution related to the temperature distribution in the hot zone and the hot zone length as a function of time are obtained. The analytical results agree well with the corresponding experimental data, and provide a quick prediction method for the heat pipe startup performance. Finally, a heat pipe limitation related to the frozen startup process is identified, and an explicit criterion for the high-temperature heat pipe startup is derived. The frozen startup limit identified in this paper provides a fundamental guidance for high-temperature heat pipe design.

Exercise mitigates the stunting effect of cold temperature on limb elongation in mice by increasing solute delivery to the growth plate

PubMed Central

Williams, Rebecca M.; Farnum, Cornelia E.

2010-01-01

Ambient temperature and physical activity modulate bone elongation in mammals, but mechanisms underlying this plasticity are a century-old enigma. Longitudinal bone growth occurs in cartilaginous plates, which receive nutritional support via delivery of solutes from the vasculature. We tested the hypothesis that chronic exercise and warm temperature promote bone lengthening by increasing solute delivery to the growth plate, measured in real time using in vivo multiphoton microscopy. We housed 68 weanling female mice at cold (16°C) or warm (25°C) temperatures and allowed some groups voluntary access to a running wheel. We show that exercise mitigates the stunting effect of cold temperature on limb elongation after 11 days of wheel running. All runners had significantly lengthened limbs, regardless of temperature, while nonrunning mice had shorter limbs that correlated with housing temperature. Tail length was impacted only by temperature, indicating that the exercise effect was localized to limb bones and was not a systemic endocrine reaction. In vivo multiphoton imaging of fluoresceinated tracers revealed enhanced solute delivery to tibial growth plates in wheel-running mice, measured under anesthesia at rest. There was a minimal effect of rearing temperature on solute delivery when measured at an intermediate room temperature (20°C), suggesting that a lasting increase in solute delivery is an important factor in exercise-mediated limb lengthening but may not play a role in temperature-mediated limb lengthening. These results are relevant to the study of skeletal evolution in mammals from varying environments and have the potential to fundamentally advance our understanding of bone elongation processes. PMID:20930127

Does Warming a Lysozyme Solution Cook Ones Data?

NASA Technical Reports Server (NTRS)

Pusey, Marc; Burke, Michael; Judge, Russell

2000-01-01

Chicken egg white lysozyme has a well characterized thermally driven phase transition. Between pH 4.0 and 5.2, the transition temperature, as defined by the point where the tetragonal and orthorhombic solubility are equal, is a function of the pH, salt (precipitant) type and concentration, and most likely of the buffer concentration as well. This phase transition can be carried out with protein solution alone, prior to the initiation of the crystallization process. We have now measured the kinetics of this process and investigated its reversibility. An aliquot of a stock protein solution is held at a given temperature, and at periodic intervals used to set up batch crystallization experiments. The batch solutions were incubated at 20 C until macroscopic crystals were obtained, at which point the number of crystals in each well were counted. The transition effects increased with temperature, slowly falling off at 30 C with a half time (time to approx. 1/2 the t = 0 number of crystals) of approx. 5 hours, and an estimated half time of approx. 0.5 hours at 43 C. Further, the process was not reversible by simple cooling. After holding a lysozyme solution at 37 C (prior to addition of precipitant) for 16 hours, then cooling and holding it at 4 C, no return to the pre-warmed nucleation kinetics are observed after at least 4 weeks. Thus every thermal excursion above the phase transition point results in a further decrease in the nucleation rate of that solution, the extent being a function of the time and temperature. Orthorhombic lysozyme crystals apparently do not undergo the flow-induced growth cessation of tetragonal lysozyme crystals. We have previously shown that putting the protein in the orthorhombic form does not affect the averaged face growth kinetics, only nucleation, for tetragonal crystals. We may be able to use this differential behavior to elucidate how flow affects tile lysozyme crystal growth process.

Densitometric evaluation of Soludent and GBX developers.

PubMed

Patel, J R

1985-01-01

A quick-developing solution (Soludent) and a new developer (Kodak GBX) were compared with a standard x-ray liquid developer. Of the three solutions evaluated, Kodak GBX solution produced slightly greater useful densities in the radiograph at all temperatures evaluated. The rapid-developing solution produced acceptable radiographs in 80% less time, with only slightly higher film fog.

Translational Diffusion Coefficient and Partition Coefficient of a Spin-Labeled Solute in Lecithin Bilayer Membranes

PubMed Central

Dix, James A.; Diamond, Jared M.; Kivelson, Daniel

1974-01-01

The translational diffusion coefficient and the partition coefficient of a spin-labeled solute, di-t-butyl nitroxide, in an aqueous suspension of dipalmitoyl lecithin vesicles have been studied by electron spin resonance spectroscopy. When the lecithin is cooled through its phase transition temperature near 41°C, some solute is “frozen out” of the bilayer, and the standard partial molar enthalpy and entropy of partition go more positive by a factor of 8 and 6, respectively. However, the apparent diffusion constant in the lecithin phase is only slightly smaller than that in water, both above and below the transition temperature. The fraction of bilayer volume within which solute is distributed may increase with temperature, contributing to the positive enthalpy of partition. Comparison of time constants suggests that there is a permeability barrier to this solute in the periphery of the bilayer. PMID:4360944

Estimating changes to groundwater discharge temperature under altered climate conditions

NASA Astrophysics Data System (ADS)

Manga, M.; Burns, E. R.; Zhu, Y.; Zhan, H.; Williams, C. F.; Ingebritsen, S.; Dunham, J.

2017-12-01

Changes in groundwater temperature resulting from climate-driven boundary conditions (recharge and land surface temperature) can be evaluated using new analytical solutions of the groundwater heat transport equation. These steady-state solutions account for land-surface boundary conditions, hydrology, and geothermal and viscous heating, and can be used to identify the key physical processes that control thermal responses of groundwater-fed ecosystems to climate change, in particular (1) groundwater recharge rate and temperature and (2) land-surface temperature transmitted through the vadose zone. Also, existing transient solutions of conduction are compared with a new solution for advective transport of heat to estimate the timing of groundwater-discharge response to changes in recharge and land surface temperature. As an example, the new solutions are applied to the volcanic Medicine Lake highlands, California, USA, and associated Fall River Springs complexes that host groundwater-dependent ecosystems. In this system, high-elevation groundwater temperatures are strongly affected only by recharge conditions, but as the vadose zone thins away from the highlands, changes to the average annual land surface temperature will also influence groundwater temperatures. Transient response to temperature change depends on both the conductive timescale and the rate at which recharge delivers heat. Most of the thermal response of groundwater at high elevations will occur within 20 years of a shift in recharge temperatures, but the lower-elevation Fall River Springs will respond more slowly, with about half of the conductive response occurring within the first 20 years and about half of the advective response to higher recharge temperatures occurring in approximately 60 years.

Interaction and dynamics of (alkylamide + electrolyte) deep eutectics: Dependence on alkyl chain-length, temperature, and anion identity

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

Guchhait, Biswajit; Das, Suman; Daschakraborty, Snehasis

Here we investigate the solute-medium interaction and solute-centered dynamics in (RCONH{sub 2} + LiX) deep eutectics (DEs) via carrying out time-resolved fluorescence measurements and all-atom molecular dynamics simulations at various temperatures. Alkylamides (RCONH{sub 2}) considered are acetamide (CH{sub 3}CONH{sub 2}), propionamide (CH{sub 3}CH{sub 2}CONH{sub 2}), and butyramide (CH{sub 3}CH{sub 2}CH{sub 2}CONH{sub 2}); the electrolytes (LiX) are lithium perchlorate (LiClO{sub 4}), lithium bromide (LiBr), and lithium nitrate (LiNO{sub 3}). Differential scanning calorimetric measurements reveal glass transition temperatures (T{sub g}) of these DEs are ∼195 K and show a very weak dependence on alkyl chain-length and electrolyte identity. Time-resolved and steady statemore » fluorescence measurements with these DEs have been carried out at six-to-nine different temperatures that are ∼100–150 K above their individual T{sub g}s. Four different solute probes providing a good spread of fluorescence lifetimes have been employed in steady state measurements, revealing strong excitation wavelength dependence of probe fluorescence emission peak frequencies. Extent of this dependence, which shows sensitivity to anion identity, has been found to increase with increase of amide chain-length and decrease of probe lifetime. Time-resolved measurements reveal strong fractional power dependence of average rates for solute solvation and rotation with fraction power being relatively smaller (stronger viscosity decoupling) for DEs containing longer amide and larger (weaker decoupling) for DEs containing perchlorate anion. Representative all-atom molecular dynamics simulations of (CH{sub 3}CONH{sub 2} + LiX) DEs at different temperatures reveal strongly stretched exponential relaxation of wavevector dependent acetamide self dynamic structure factor with time constants dependent both on ion identity and temperature, providing justification for explaining the fluorescence results in terms of temporal heterogeneity and amide clustering in these multi-component melts.« less

Inorganic-polymer-derived dielectric films

DOEpatents

Brinker, C.J.; Keefer, K.D.; Lenahan, P.M.

1985-02-25

A method is disclosed for coating a substrate with a thin film of a predetermined porosity. The method comprises: depositing the thin film on the substrate from a non-gelled solution comprising at least one metal alkoxide of a polymeric network forming cation, water, an alcohol compatible with the hydrolysis and the polymerization of the metal alkoxide, and an acid or a base; prior to said depositing step, controlling the porosity and structure of said coating for a given composition of said solution exclusive of the acid or base component and the water component, by adjusting each of the water content, the pH, the temperature and the time of standing of said solution, increasing/descreasing the water content or the pH to increase/decrease the pore size of said coating, and increasing/decreasing the temperature or time of standing of said solution to increase/decrease the pore size of said coating; and curing said deposited film at a temperature effective for curing whereby there is obtained a thin film coating of a predetermined porosity on the substrate.

Parameter optimization of electrolytic process of obtaining sodium hypochlorite for disinfection of water

NASA Astrophysics Data System (ADS)

Bogoslovskii, S. Yu; Kuznetsov, N. N.; Boldyrev, V. S.

2017-11-01

Electrochlorination parameters were optimized in flowing and non-flowing modes for a cell with a volume of 1 l. At a current density of 0.1 A/cm2 in the range of flow rates from 0.8 to 6.0 l/h with a temperature of the initial solution below 20°C the outlet temperature is maintained close to the optimal 40°C. The pH of the solution during electrolysis increases to 8.8 ÷ 9.4. There was studied a process in which a solution with a temperature of 7-8°C and a concentration of sodium chloride of 25 and 35 g/l in non-flowing cell was used. The dependence of the concentration of active chlorine on the electrolysis time varies with the concentration of the initial solution of sodium chloride. In case of chloride concentration of 25 g/l virtually linear relationship makes it easy to choose the time of electrolysis with the aim of obtaining the needed concentration of the product.

HEATING 7. 1 user's manual

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

Childs, K.W.

1991-07-01

HEATING is a FORTRAN program designed to solve steady-state and/or transient heat conduction problems in one-, two-, or three- dimensional Cartesian, cylindrical, or spherical coordinates. A model may include multiple materials, and the thermal conductivity, density, and specific heat of each material may be both time- and temperature-dependent. The thermal conductivity may be anisotropic. Materials may undergo change of phase. Thermal properties of materials may be input or may be extracted from a material properties library. Heating generation rates may be dependent on time, temperature, and position, and boundary temperatures may be time- and position-dependent. The boundary conditions, which maymore » be surface-to-boundary or surface-to-surface, may be specified temperatures or any combination of prescribed heat flux, forced convection, natural convection, and radiation. The boundary condition parameters may be time- and/or temperature-dependent. General graybody radiation problems may be modeled with user-defined factors for radiant exchange. The mesh spacing may be variable along each axis. HEATING is variably dimensioned and utilizes free-form input. Three steady-state solution techniques are available: point-successive-overrelaxation iterative method with extrapolation, direct-solution (for one-dimensional or two-dimensional problems), and conjugate gradient. Transient problems may be solved using one of several finite-difference schemes: Crank-Nicolson implicit, Classical Implicit Procedure (CIP), Classical Explicit Procedure (CEP), or Levy explicit method (which for some circumstances allows a time step greater than the CEP stability criterion). The solution of the system of equations arising from the implicit techniques is accomplished by point-successive-overrelaxation iteration and includes procedures to estimate the optimum acceleration parameter.« less

Ice Growth Inhibition in Antifreeze Polypeptide Solution by Short-Time Solution Preheating.

PubMed

Nishi, Naoto; Miyamoto, Takuya; Waku, Tomonori; Tanaka, Naoki; Hagiwara, Yoshimichi

2016-01-01

The objective of this study is to enhance the inhibition of ice growth in the aqueous solution of a polypeptide, which is inspired by winter flounder antifreeze protein. We carried out measurements on unidirectional freezing of the polypeptide solution. The thickness of the solution was 0.02 mm, and the concentration of polypeptide was varied from 0 to 2 mg/mL. We captured successive microscopic images of ice/solution interfaces, and measured the interface velocity from the locations of tips of the pectinate interface in the images. We also simultaneously measured the temperature by using a small thermocouple. The ice/solution interface temperature was defined by the temperature at the tips. It was found that the interface temperature was decreased with an increasing concentration of polypeptide. To try varying the activity of the polypeptide, we preheated the polypeptide solution and cooled it before carrying out the measurements. Preheating for 1-5 hours was found to cause a further decrease in the interface temperature. Furthermore, wider regions of solution and ice with inclined interfaces in the pectinate interface structure were observed, compared with the case where the solution was not preheated. Thus, the ice growth inhibition was enhanced by this preheating. To investigate the reason for this enhancement, we measured the conformation and aggregates of polypeptide in the solution. We also measured the local concentration of polypeptide. It was found that the polypeptide aggregates became larger as a result of preheating, although the polypeptide conformation was unchanged. These large aggregates caused both adsorption to the interface and the wide regions of supercooled solution in the pectinate interface structure.

Investigating the synthesis of ligated metal clusters in solution using a flow reactor and electrospray ionization mass spectrometry.

PubMed

Olivares, Astrid; Laskin, Julia; Johnson, Grant E

2014-09-18

The scalable synthesis of ligated subnanometer metal clusters containing an exact number of atoms is of interest due to the highly size-dependent catalytic, electronic, and optical properties of these species. While significant research has been conducted on the batch preparation of clusters through reduction synthesis in solution, the processes of metal complex reduction as well as cluster nucleation, growth, and postreduction etching are still not well understood. Herein, we demonstrate a prototype temperature-controlled flow reactor for qualitatively studying cluster formation in solution at steady-state conditions. Employing this technique, methanol solutions of a chloro(triphenylphosphine)gold precursor, 1,4-bis(diphenylphosphino)butane capping ligand, and borane-tert-butylamine reducing agent were combined in a mixing tee and introduced into a heated capillary with a known length. In this manner, the temperature dependence of the relative abundance of different ionic reactants, intermediates, and products synthesized in real time was characterized qualitatively using online mass spectrometry. A wide distribution of doubly and triply charged cationic gold clusters was observed as well as smaller singly charged organometallic complexes. The results demonstrate that temperature plays a crucial role in determining the relative population of cationic gold clusters and, in general, that higher temperature promotes the formation of doubly charged clusters and singly charged organometallic complexes while reducing the abundance of triply charged species. Moreover, the distribution of clusters observed at elevated temperatures is found to be consistent with that obtained at longer reaction times at room temperature, thereby demonstrating that heating may be used to access cluster distributions characteristic of different stages of batch reduction synthesis in solution.

Effect of temperature on copper, iron and lead leaching from e-waste using citrate solutions.

PubMed

Torres, Robinson; Segura-Bailón, Brenda; Lapidus, Gretchen T

2018-01-01

E-waste is a potential source of large quantities of metals. The ability of citrate solutions to recover base metals from these materials has been demonstrated. In the present study, the effect of the temperature on base metal leaching capacity by the citrate solutions is determined. The material employed consisted of a mechanically prepared, gravity concentrated e-waste, with a metallic content greater than 90%. The leaching conditions were selected based on previous research performed by the authors (0.5 M sodium citrate, pH 4.5 and 20 g per liter e-waste concentrate). Leaching tests were performed at temperatures between 0° and 70 °C. The initial leaching rates for the three metals increased with temperature. However, these tapered off with time for temperatures above 30 °C, which can be associated to citrate destruction. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of aging heat time and annealing temperature on the properties of nanocrystalline tin dioxide thin films

NASA Astrophysics Data System (ADS)

Kadhim, Imad H.; Abu Hassan, H.

2017-04-01

Nanocrystalline tin dioxide (SnO2) thin films have been successfully prepared by sol-gel spin-coating technique on p-type Si (100) substrates. A stable solution was prepared by mixing tin(II) chloride dihydrate, pure ethanol, and glycerin. Temperature affects the properties of SnO2 thin films, particularly the crystallite size where the crystallization of SnO2 with tetragonal rutile structure is achieved when thin films that prepared under different aging heat times are annealed at 400∘C. By increasing aging heat time in the presence of annealing temperatures the FESEM images indicated that the thickness of the fabricated film was directly proportional to solution viscosity, increasing from approximately 380 nm to 744 nm, as well as the crystallization of the thin films improved and reduced defects.

Lower Critical Solubility Temperature Behavior in Membranes Formed from a 2-(2-Methoxyethoxy)ethoxy-Containing Polyphosphazene

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

Stewart, F.F.; Lash, R.P.

A phosphazene polymer with three pendant groups was synthesized and characterized as a membrane material. Substitution of the phosphazene with 64% 2-(2-methoxyethoxy)ethanol (MEE), 27% 4-methoxyphenol, and 9% 2-allyphenol yielded a hydrophilic elastomer with considerable flow at room temperature. Solution behavior showed significant aging effects where, using fresh solutions, membranes could not cast on porous ceramic supports (0.2-micron pore size) without significant polymer penetration into the pores. Solutions aged for two weeks were found to readily penetrate into the pores of the ceramic support. Analysis of fresh and aged solutions by laser light scattering showed significant loss in molecular weight withmore » time. Pervaporation of water-dye solutions using dimensionally stabilized membranes revealed in inverse correlation between flux and temperature, suggesting thermally induced morphological changes within the polymer. This polymer was found to exhibit, in the bulk state, lower critical solubility temperature (LCST) behavior where the material becomes less hydrophilic with increasing temperature. LCST behavior was probed thermally and gravimetrically and has been attributed to the anomalous pervaporation results. The degree to which LCST effects membrane transport was influenced by changes in the crosslink density and permeate side pressure.« less

Segregation effects during solidification in weightless melts

NASA Technical Reports Server (NTRS)

Li, C.; Gershinsky, M.

1974-01-01

The generalized problem of determining the temperature and solute concentration profiles during directional solidification of binary alloys with surface evaporation was mathematically formulated. Realistic initial and boundary conditions were defined, and a computer program was developed and checked out. The programs computes the positions of two moving boundaries, evaporation and solidification, and their velocities. Temperature and solute concentration profiles in the semiinfinite material body at selected instances of time are also computed.

Mathematical analysis of thermal diffusion shock waves

NASA Astrophysics Data System (ADS)

Gusev, Vitalyi; Craig, Walter; Livoti, Roberto; Danworaphong, Sorasak; Diebold, Gerald J.

2005-10-01

Thermal diffusion, also known as the Ludwig-Soret effect, refers to the separation of mixtures in a temperature gradient. For a binary mixture the time dependence of the change in concentration of each species is governed by a nonlinear partial differential equation in space and time. Here, an exact solution of the Ludwig-Soret equation without mass diffusion for a sinusoidal temperature field is given. The solution shows that counterpropagating shock waves are produced which slow and eventually come to a halt. Expressions are found for the shock time for two limiting values of the starting density fraction. The effects of diffusion on the development of the concentration profile in time and space are found by numerical integration of the nonlinear differential equation.

Measurements of thermodynamic and optical properties of selected aqueous organic and organic-inorganic mixtures of atmospheric relevance.

PubMed

Lienhard, Daniel M; Bones, David L; Zuend, Andreas; Krieger, Ulrich K; Reid, Jonathan P; Peter, Thomas

2012-10-11

Atmospheric aerosol particles can exhibit liquid solution concentrations supersaturated with respect to the dissolved organic and inorganic species and supercooled with respect to ice. In this study, thermodynamic and optical properties of sub- and supersaturated aqueous solutions of atmospheric interest are presented. The density, refractive index, water activity, ice melting temperatures, and homogeneous ice freezing temperatures of binary aqueous solutions containing L(+)-tartaric acid, tannic acid, and levoglucosan and ternary aqueous solutions containing levoglucosan and one of the salts NH(4)HSO(4), (NH(4))(2)SO(4), and NH(4)NO(3) have been measured in the supersaturated concentration range for the first time. In addition, the density and refractive index of binary aqueous citric acid and raffinose solutions and the glass transition temperatures of binary aqueous L(+)-tartaric acid and levoglucosan solutions have been measured. The data presented here are derived from experiments on single levitated microdroplets and bulk solutions and should find application in thermodynamic and atmospheric aerosol models as well as in food science applications.

Effect of Process Parameter on Barium Titanate Stannate (BTS) Materials Sintered at Low Sintering

NASA Astrophysics Data System (ADS)

Shukla, Alok; Bajpai, P. K.

2011-11-01

Ba(Ti1-xSnx)O3 solid solutions with (x = 0.15, 0.20, 0.30 and 0.40) are synthesized using conventional solid state reaction method. Formation of solid solutions in the range 0 ≤ x ≤0.40 is confirmed using X-ray diffraction technique. Single phase solid solutions with homogeneous grain distribution are observed at relatively low sintering by controlling process parameters viz. sintering time. Composition at optimized temperature (1150 °C) sintered by varying the sintering time, stabilize in cubic perovskite phase. The % experimental density increase with increasing the time of sintering instead of increasing sintering temperature. The lattice parameter increases by increasing the tin composition in the material. This demonstrates that process parameter optimization can lead to single phase at relatively lower sintering-a major advantage for the materials used as capacitor element in MLCC.

Modelling transient temperature distribution for injecting hot water through a well to an aquifer thermal energy storage system

NASA Astrophysics Data System (ADS)

Yang, Shaw-Yang; Yeh, Hund-Der; Li, Kuang-Yi

2010-10-01

Heat storage systems are usually used to store waste heat and solar energy. In this study, a mathematical model is developed to predict both the steady-state and transient temperature distributions of an aquifer thermal energy storage (ATES) system after hot water is injected through a well into a confined aquifer. The ATES has a confined aquifer bounded by aquicludes with different thermomechanical properties and geothermal gradients along the depth. Consider that the heat is transferred by conduction and forced convection within the aquifer and by conduction within the aquicludes. The dimensionless semi-analytical solutions of temperature distributions of the ATES system are developed using Laplace and Fourier transforms and their corresponding time-domain results are evaluated numerically by the modified Crump method. The steady-state solution is obtained from the transient solution through the final-value theorem. The effect of the heat transfer coefficient on aquiclude temperature distribution is appreciable only near the outer boundaries of the aquicludes. The present solutions are useful for estimating the temperature distribution of heat injection and the aquifer thermal capacity of ATES systems.

Analysis of temperature time series to estimate direction and magnitude of water fluxes in near-surface sediments

NASA Astrophysics Data System (ADS)

Munz, Matthias; Oswald, Sascha E.; Schmidt, Christian

2017-04-01

The application of heat as a hydrological tracer has become a standard method for quantifying water fluxes between groundwater and surface water. Typically, time series of temperatures in the surface water and in the sediment are observed and are subsequently evaluated by a vertical 1D representation of heat transport by advection and dispersion. Several analytical solutions as well as their implementation into user-friendly software exist in order to estimate water fluxes from the observed temperatures. The underlying assumption of a stationary, one-dimensional vertical flow field is frequently violated in natural systems. Here subsurface water flow often has a significant horizontal component. We developed a methodology for identifying the geometry of the subsurface flow field based on the variations of diurnal temperature amplitudes with depths. For instance: Purely vertical heat transport is characterized by an exponential decline of temperature amplitudes with increasing depth. Pure horizontal flow would be indicated by a constant, depth independent vertical amplitude profile. The decline of temperature amplitudes with depths could be fitted by polynomials of different order whereby the best fit was defined by the highest Akaike Information Criterion. The stepwise model optimization and selection, evaluating the shape of vertical amplitude ratio profiles was used to determine the predominant subsurface flow field, which could be systematically categorized in purely vertical and horizontal (hyporheic, parafluvial) components. Analytical solutions to estimate water fluxes from the observed temperatures are restricted to specific boundary conditions such as a sinusoidal upper temperature boundary. In contrast numerical solutions offer higher flexibility and can handle temperature data which is characterized by irregular variations such as storm-event induced temperature changes and thus cannot readily be incorporated in analytical solutions. There are several numerical models that simulate heat transport in porous media (e.g. VS2DH, HydroGeoSphere, FEFLOW) but there can be a steep learning curve to the modelling frameworks and may therefore not readily accessible to routinely infer water fluxes between groundwater and surface water. We developed a user-friendly, straightforeward to use software to estimate water FLUXes Based On Temperatures- FLUX-BOT. FLUX-BOT is a numerical code written in MATLAB that calculates time variable vertical water fluxes in saturated sediments based on the inversion of measured temperature time series observed at multiple depths. It applies a cell-centered Crank-Nicolson implicit finite difference scheme to solve the one-dimensional heat advection-conduction equation (FLUX-BOT can be downloaded from the following web site: https://bitbucket.org/flux-bot/flux-bot). We provide applications of FLUX-BOT to generic as well as to measured temperature data to demonstrate its performance. Both, the empirical analysis of temperature amplitudes as well as the numerical inversion of measured temperature time series to estimate the vertical magnitude of water fluxes extent the suite of current heat tracing methods and may provide insight into temperature data from an additional perspective.

Octanol reduces end-plate channel lifetime

PubMed Central

Gage, Peter W.; McBurney, Robert N.; Van Helden, Dirk

1978-01-01

1. Post-synaptic effects of n-octanol at concentrations of 0·1-1 mM were examined in toad sartorius muscles by use of extracellular and voltage-clamp techniques. 2. Octanol depressed the amplitude and duration of miniature end-plate currents and hence depressed neuromuscular transmission. 3. The decay of miniature end-plate currents remained exponential in octanol solutions even when the time constant of decay (τD) was decreased by 80-90%. 4. The lifetime of end-plate channels, obtained by analysis of acetylcholine noise, was also decreased by octanol. The average lifetime measured from noise spectra agreed reasonably well with the time constant of decay of miniature end-plate currents, both in control solution and in octanol solutions. 5. Octanol caused a reduction in the conductance of end-plate channels. Single channel conductance was on average about 25 pS in control solution and 20 pS in octanol. 6. In most cells the normal voltage sensitivity of the decay of miniature end-plate currents was retained in octanol solutions. The lifetime of end-plate channels measured from acetylcholine noise also remained voltage-sensitive in octanol solutions. In some experiments in which channel lifetime was exceptionally reduced the voltage sensitivity was less than normal. 7. In octanol solutions, τD was still very sensitive to temperature changes in most cells although in some the temperature sensitivity of τD was clearly reduced. Changes in τD with temperature could generally be fitted by the Arrhenius equation suggesting that a single step reaction controlled the decay of currents both in control and in octanol solutions. In some cells in which τD became less than 0·3 ms, the relationship between τD and temperature became inconsistent with the Arrhenius equation. 8. As the decay of end-plate currents in octanol solutions remains exponential, and the voltage and temperature sensitivity can be unchanged even when τD is significantly reduced, it seems likely that octanol decreases τD by increasing the rate of the reaction which normally controls the lifetime of end-plate channels. PMID:203674

Study of Sigma Phase in Duplex SAF 2507

NASA Astrophysics Data System (ADS)

Fellicia, D. M.; Sutarsis; Kurniawan, B. A.; Wulanari, D.; Purniawan, A.; Wibisono, A. T.

2017-05-01

Super duplex stainless steel is one of the stainless steel which has a combination between high strength properties and excellent corrosion resistance. However, the resistance can decrease by precipitation of sigma phase which is formed at high temperature, for example after welding processes. A series of experiments has been performed to study the effect of solution annealing to existence of sigma phase on super duplex SAF 2507. Variations of solution-annealing temperatures were 1000 °C, 1065 °C and 1125 °C with holding time of 15 and 30 minutes for each temperature. Effect of solution annealing process was characterized by using XRD, SEM, and Optical Microscopy. The result showed precipitation of sigma phase completely dissolved at 1065 °C and 1125 °C because it reformed to austenite. After it was heated at 1065 °C, chromium carbide appeared in ferrite site and grain boundary. The amount of chromium carbide increased with the increasing of solution annealing temperature.

Dynamical properties in supercooling liquid of trehalose aqueous solution studied by Brillouin scattering

NASA Astrophysics Data System (ADS)

Shibata, Tomohiko; Tominaga, Ayane; Takayama, Haruki; Kojima, Seiji

2013-02-01

Brillouin scattering spectroscopy has been applied to study the dynamical properties of glass transition of trehalose aqueous solutions in a high-frequency gigahertz range and in the temperature range (-190°C ≤ T ≤ 100°C). The temperature variations of sound velocity and attenuation were accurately determined using the refractive index measured by a prism-coupling method. The temperature dependence of relaxation time of the structural relaxation process was determined by the Debye model. Its temperature dependence shows Arrhenius behavior in a liquid state. The parameters of Arrhenius law were also determined as a function of trehalose concentration.

Direct solution for thermal stresses in a nose cap under an arbitrary axisymmetric temperature distribution

NASA Technical Reports Server (NTRS)

Davis, Randall C.

1988-01-01

The design of a nose cap for a hypersonic vehicle is an iterative process requiring a rapid, easy to use and accurate stress analysis. The objective of this paper is to develop such a stress analysis technique from a direct solution of the thermal stress equations for a spherical shell. The nose cap structure is treated as a thin spherical shell with an axisymmetric temperature distribution. The governing differential equations are solved by expressing the stress solution to the thermoelastic equations in terms of a series of derivatives of the Legendre polynomials. The process of finding the coefficients for the series solution in terms of the temperature distribution is generalized by expressing the temperature along the shell and through the thickness as a polynomial in the spherical angle coordinate. Under this generalization the orthogonality property of the Legendre polynomials leads to a sequence of integrals involving powers of the spherical shell coordinate times the derivative of the Legendre polynomials. The coefficients of the temperature polynomial appear outside of these integrals. Thus, the integrals are evaluated only once and their values tabulated for use with any arbitrary polynomial temperature distribution.

Dynamical properties of water-methanol solutions

NASA Astrophysics Data System (ADS)

Mallamace, Francesco; Corsaro, Carmelo; Mallamace, Domenico; Vasi, Cirino; Vasi, Sebastiano; Stanley, H. Eugene

2016-02-01

We study the relaxation times tα in the water-methanol system. We examine new data and data from the literature in the large temperature range 163 < T < 335 K obtained using different experimental techniques and focus on how tα affects the hydrogen bond structure of the system and the hydrophobicity of the alcohol methyl group. We examine the relaxation times at a fixed temperature as a function of the water molar fraction XW and observe two opposite behaviors in their curvature when the system moves from high to low T regimes. This behavior differs from that of an ideal solution in that it has excess values located at different molar fractions (XW = 0.5 for high T and 0.75 in the deep supercooled regime). We analyze the data and find that above a crossover temperature T ˜ 223 K, hydrophobicity plays a significant role and below it the water tetrahedral network dominates. This temperature is coincident with the fragile-to-strong dynamical crossover observed in confined water and supports the liquid-liquid phase transition hypothesis. At the same time, the reported data suggest that this crossover temperature (identified as the Widom line temperature) also depends on the alcohol concentration.

Direct synthesis of zirconium powder by magnesium reduction

NASA Astrophysics Data System (ADS)

Lee, Dong-Won; Yun, Jung-Yeul; Yoon, Sung-Won; Wang, Jei-Pil

2013-05-01

The direct synthesis of zirconium powder has been conducted through an analysis of the chemical reaction between evaporated ZrCl4 and molten magnesium over a range of reduction temperatures, concentration of hydrochloric acid, and stirring time. The observed results indicated that the purity of zirconium powder increased with increased stirring time, and Mg and MgCl2 were removed by 10 wt% of hydrochloric acid solution. The pure zirconium powder was obtained by stirring again for 5 h using 5 wt% of hydrochloric acid solution. It was noted that the mean particle size increased when the reaction temperature was increased, and the size of the powder at 1,123 K and 1,173 K was found to be 10 μm and 15 μm, respectively. In addition, the purity of the powder was also improved with temperature, and its purity finally reached up to 99.5% at 1,250 K. Overall, pure zirconium powder was obtained after a stirring stage for 5 hours using 5 wt% of hydrochloric acid solution.

Porous silicon powder as an adsorbent of heavy metal (nickel)

NASA Astrophysics Data System (ADS)

Nabil, Marwa; Motaweh, Hussien A.

2018-04-01

New and inexpensive nanoporous silicon (NPS) powder was prepared by alkali chemical etching using sonication technique and was subsequently investigated as an adsorbent in batch systems for the adsorption Ni(II) ions in an aqueous solution. The optimum conditions for the Ni(II) ion adsorption capacity of the NPS powder were studied in detail by varying parameters such as the initial Ni(II) concentration, the solution pH value, the adsorption temperature and contact time. The results indicated that the maximum adsorption capacity and the maximum removal percent of Ni(II) reached 2665.33 mg/g and 82.6%, respectively, at an initial Ni(II) concentration of 100 mg/L, adsorption time of 30 min and no effect of the solution pH and adsorption temperature.

Temperature-dependent sorption of naphthalene, phenanthrene, and pyrene to low organic carbon aquifer sediments

USGS Publications Warehouse

Piatt, Joseph J.; Backhus, Debera A.; Capel, Paul D.; Eisenreich, Steven J.

1996-01-01

Sorption experiments were conducted with naphthalene, phenanthrene, and pyrene on low organic carbon sediments at 4 and 26 °C using batch and column techniques. Experimental controls ensured the absence of biologic and photolytic activity and colloid-free solution supernatants. Equilibrium distribution coefficients (Kd) increased 1.1−1.6 times with a decrease in temperature of 22 °C. Fraction instantaneous sorption (F) values did not change significantly with a decrease in temperature of 22 °C. Desorption rate constants (k2) decreased 1.2−2.6 times with a decrease in temperature of 22 °C. Times to equilibrium were at least 40 h. The magnitude of observed Kd and k2 values and the effect of temperature on Kd (e.g., low enthalpy of sorption) are consistent with sorbate partitioning between the aqueous phase and small amounts of organic matter (foc = 0.02%) on the sediments. The temperature dependence of Kd and k2 may be small as compared to the effects of heterogeneities in field-scale aquifer systems. Thus, thermal gradients may not be of major importance in most saturated subsurface regimes when predicting solute transport. However, aquifer remediation pump-and-treat times could be decreased because increased temperature decreases both retardation and tailing.

Electronic Structure of Low-Temperature Solution-Processed Amorphous Metal Oxide Semiconductors for Thin-Film Transistor Applications

PubMed Central

Socratous, Josephine; Banger, Kulbinder K; Vaynzof, Yana; Sadhanala, Aditya; Brown, Adam D; Sepe, Alessandro; Steiner, Ullrich; Sirringhaus, Henning

2015-01-01

The electronic structure of low temperature, solution-processed indium–zinc oxide thin-film transistors is complex and remains insufficiently understood. As commonly observed, high device performance with mobility >1 cm2 V−1 s−1 is achievable after annealing in air above typically 250 °C but performance decreases rapidly when annealing temperatures ≤200 °C are used. Here, the electronic structure of low temperature, solution-processed oxide thin films as a function of annealing temperature and environment using a combination of X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and photothermal deflection spectroscopy is investigated. The drop-off in performance at temperatures ≤200 °C to incomplete conversion of metal hydroxide species into the fully coordinated oxide is attributed. The effect of an additional vacuum annealing step, which is beneficial if performed for short times at low temperatures, but leads to catastrophic device failure if performed at too high temperatures or for too long is also investigated. Evidence is found that during vacuum annealing, the workfunction increases and a large concentration of sub-bandgap defect states (re)appears. These results demonstrate that good devices can only be achieved in low temperature, solution-processed oxides if a significant concentration of acceptor states below the conduction band minimum is compensated or passivated by shallow hydrogen and oxygen vacancy-induced donor levels. PMID:26190964

Electronic Structure of Low-Temperature Solution-Processed Amorphous Metal Oxide Semiconductors for Thin-Film Transistor Applications.

PubMed

Socratous, Josephine; Banger, Kulbinder K; Vaynzof, Yana; Sadhanala, Aditya; Brown, Adam D; Sepe, Alessandro; Steiner, Ullrich; Sirringhaus, Henning

2015-03-25

The electronic structure of low temperature, solution-processed indium-zinc oxide thin-film transistors is complex and remains insufficiently understood. As commonly observed, high device performance with mobility >1 cm 2 V -1 s -1 is achievable after annealing in air above typically 250 °C but performance decreases rapidly when annealing temperatures ≤200 °C are used. Here, the electronic structure of low temperature, solution-processed oxide thin films as a function of annealing temperature and environment using a combination of X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and photothermal deflection spectroscopy is investigated. The drop-off in performance at temperatures ≤200 °C to incomplete conversion of metal hydroxide species into the fully coordinated oxide is attributed. The effect of an additional vacuum annealing step, which is beneficial if performed for short times at low temperatures, but leads to catastrophic device failure if performed at too high temperatures or for too long is also investigated. Evidence is found that during vacuum annealing, the workfunction increases and a large concentration of sub-bandgap defect states (re)appears. These results demonstrate that good devices can only be achieved in low temperature, solution-processed oxides if a significant concentration of acceptor states below the conduction band minimum is compensated or passivated by shallow hydrogen and oxygen vacancy-induced donor levels.

Impact of heat treatment on the physical properties of noncrystalline multisolute systems concentrated in frozen aqueous solutions.

PubMed

Izutsu, Ken-ichi; Yomota, Chikako; Kawanishi, Toru

2011-12-01

The purpose of this study was to elucidate the effect of heat treatment on the miscibility of multiple concentrated solutes that mimic biopharmaceutical formulations in frozen solutions. The first heating thermal analysis of frozen solutions containing either a low-molecular-weight saccharide (e.g., sucrose, trehalose, and glucose) or a polymer (e.g., polyvinylpyrrolidone and dextran) and their mixtures from -70°C showed a single transition at glass transition temperature of maximally freeze-concentrated solution (T(g) ') that indicated mixing of the freeze-concentrated multiple solutes. The heat treatment of single-solute and various polymer-rich mixture frozen solutions at temperatures far above their T(g) ' induced additional ice crystallization that shifted the transitions upward in the following scan. Contrarily, the heat treatment of frozen disaccharide-rich solutions induced two-step heat flow changes (T(g) ' splitting) that suggested separation of the solutes into multiple concentrated noncrystalline phases, different in the solute compositions. The extent of the T(g) ' splitting depended on the heat treatment temperature and time. Two-step glass transition was observed in some sucrose and dextran mixture solids, lyophilized after the heat treatment. Increasing mobility of solute molecules during the heat treatment should allow spatial reordering of some concentrated solute mixtures into thermodynamically favorable multiple phases. Copyright © 2011 Wiley-Liss, Inc.

Thermodynamic aspects of cluster crystallization in cryoprotective solutions.

PubMed

Osetsky, A I

2011-01-01

Crystallization of the solutions with quite a high intermolecular interaction of the components is analyzed. For the first time there has been considered the phenomenon of cluster crystallization of these solutions, enabling the reduction of total energy of intermolecular bonds, broken down during crystallization of the components has been discussed. A special priority is given to the cluster crystallization of aqueous solutions of cryoprotective substances close to vitrification temperature. Within this temperature range the mechanism of cluster crystallization is especially effective due to a sharp reduction of sizes of critical ice nucleation centers and diffusion mobility of molecules. This should be taken into account when designing the cryopreservation protocols for biological systems.

Method for producing small hollow spheres

DOEpatents

Rosencwaig, Allen; Koo, Jackson C.; Dressler, John L.

1981-01-01

A method for producing small hollow spheres of glass having an outer diameter ranging from about 100.mu. to about 500.mu. with a substantially uniform wall thickness in the range of about 0.5-20.mu.. The method involves introducing aqueous droplets of a glass-forming solution into a long vertical drop oven or furnace having varying temperature regions. In one embodiment, one of the temperature regions is lower than both the preceeding region and the subsequent region. One region utilizes a temperature of at least 200.degree. C. higher than the melting point of the glass-forming material in the solution and, for example, may be at least 3 times higher than the temperature of the preceeding region. In addition, there is a sharp temperature gradient between these regions. As each droplet of solution passes through a first region it forms into a gel membrane having a spherical shape and encapsulates the rest of the drop retained in the elastic outer surface and the water entrapped within diffuses rapidly through the thin gel membrane which causes more of the glass-forming material to go out of solution and is incorporated into the gel membrane causing it to grow in size and become hollow. thus produced hollow glass sphere has a sphericity, concentricity, and wall uniformity of better than 5%. The sphere is capable of retaining material of up to at least 100 atmospheres therein over long periods of time. In one embodiment.

Formation of high-temperature superconductor films during the nonstationary laser heating of liquid metal carboxylate solutions

NASA Astrophysics Data System (ADS)

Borman, V. D.; Dudko, S. A.; Sinitsyn, I. V.; Troian, V. I.; Filippov, E. A.

1989-01-01

It has been shown in earlier studies that high-temperature superconductor films can be produced through the decomposition of metal (Y, Ba, Cu) carboxylates in a liquid solution film. In the present study, the effect of nonstationary laser heating on the composition and properties of the complex oxide films formed by this method is examined with reference to experimental results obtained for YBa2Cu3O(x) films. It is shown that the chemical composition and properties of films formed in metal carboxylate solutions can be controlled by varying the time of laser heating.

Effect of mixing, concentration and temperature on the formation of mesostructured solutions and their role in the nucleation of DL-valine crystals.

PubMed

Jawor-Baczynska, Anna; Moore, Barry D; Sefcik, Jan

2015-01-01

We report investigations on the formation of mesostructured solutions in DL-valine-water-2-propanol mixtures, and the crystallization of DL-valine from these solutions. Mesostructured liquid phases, similar to those previously observed in aqueous solutions of glycine and DL-alanine, were observed using Dynamic Light Scattering and Brownian microscopy, in both undersaturated and supersaturated solutions below a certain transition temperature. Careful experimentation was used to demonstrate that the optically clear mesostructured liquid phase, comprising colloidal mesoscale clusters dispersed within bulk solution, is thermodynamically stable and present in equilibrium with the solid phase at saturation conditions. Solutions prepared by slow cooling contained mesoscale clusters with a narrow size distribution and a mean hydrodynamic diameter of around 200 nm. Solutions of identical composition prepared by rapid isothermal mixing of valine aqueous solutions with 2-propanol contained mesoscale clusters which were significantly larger than those observed in slowly cooled solutions. The presence of larger mesoscale clusters was found to correspond to faster nucleation. Observed induction times were strongly dependent on the rapid initial mixing step, although solutions were left undisturbed afterwards and the induction times observed were up to two orders of magnitude longer than the initial mixing period. We propose that mesoscale clusters above a certain critical size are likely to be the location of productive nucleation events.

Interpreting Repeated Temperature-Depth Profiles for Groundwater Flow

NASA Astrophysics Data System (ADS)

Bense, Victor F.; Kurylyk, Barret L.; van Daal, Jonathan; van der Ploeg, Martine J.; Carey, Sean K.

2017-10-01

Temperature can be used to trace groundwater flows due to thermal disturbances of subsurface advection. Prior hydrogeological studies that have used temperature-depth profiles to estimate vertical groundwater fluxes have either ignored the influence of climate change by employing steady-state analytical solutions or applied transient techniques to study temperature-depth profiles recorded at only a single point in time. Transient analyses of a single profile are predicated on the accurate determination of an unknown profile at some time in the past to form the initial condition. In this study, we use both analytical solutions and a numerical model to demonstrate that boreholes with temperature-depth profiles recorded at multiple times can be analyzed to either overcome the uncertainty associated with estimating unknown initial conditions or to form an additional check for the profile fitting. We further illustrate that the common approach of assuming a linear initial temperature-depth profile can result in significant errors for groundwater flux estimates. Profiles obtained from a borehole in the Veluwe area, Netherlands in both 1978 and 2016 are analyzed for an illustrative example. Since many temperature-depth profiles were collected in the late 1970s and 1980s, these previously profiled boreholes represent a significant and underexploited opportunity to obtain repeat measurements that can be used for similar analyses at other sites around the world.

Hydrogen embrittlement of work-hardened Ni-Ti alloy in fluoride solutions.

PubMed

Yokoyama, Ken'ichi; Kaneko, Kazuyuki; Ogawa, Toshio; Moriyama, Keiji; Asaoka, Kenzo; Sakai, Jun'ichi

2005-01-01

Hydrogen embrittlement of work-hardened Ni-Ti alloy has been examined in acidulated phosphate fluoride (APF) solutions. Upon immersion in a 2.0% APF solution with a pH of 5.0, tensile strength decreased markedly with immersion time. Moreover, the fracture mode changed from ductile to brittle due to brittle layer formation at the peripheral part of the cross section of the specimen. The amount of absorbed hydrogen increased linearly with immersion time, and it reached above 5000 mass ppm after 24 h. The hydrogen desorption temperature of the immersed specimens shifted from 450 degrees C to a lower temperature with immersion time. As the amount of absorbed hydrogen was larger than 500 mass ppm, the degradation of mechanical properties was recognized. Although the tensile properties and fracture mode scarcely change in a 0.2% APF solution, the slight reduction in hardness and hydrogen absorption of several hundreds mass ppm were observed. The results of the present study imply that work-hardened Ni-Ti alloy is less sensitive to hydrogen embrittlement compared with Ni-Ti superelastic alloy. Copyright 2004 Elsevier Ltd.

Fundamental Flux Equations for Fracture-Matrix Interactions with Linear Diffusion

NASA Astrophysics Data System (ADS)

Oldenburg, C. M.; Zhou, Q.; Rutqvist, J.; Birkholzer, J. T.

2017-12-01

The conventional dual-continuum models are only applicable for late-time behavior of pressure propagation in fractured rock, while discrete-fracture-network models may explicitly deal with matrix blocks at high computational expense. To address these issues, we developed a unified-form diffusive flux equation for 1D isotropic (spheres, cylinders, slabs) and 2D/3D rectangular matrix blocks (squares, cubes, rectangles, and rectangular parallelepipeds) by partitioning the entire dimensionless-time domain (Zhou et al., 2017a, b). For each matrix block, this flux equation consists of the early-time solution up until a switch-over time after which the late-time solution is applied to create continuity from early to late time. The early-time solutions are based on three-term polynomial functions in terms of square root of dimensionless time, with the coefficients dependent on dimensionless area-to-volume ratio and aspect ratios for rectangular blocks. For the late-time solutions, one exponential term is needed for isotropic blocks, while a few additional exponential terms are needed for highly anisotropic blocks. The time-partitioning method was also used for calculating pressure/concentration/temperature distribution within a matrix block. The approximate solution contains an error-function solution for early times and an exponential solution for late times, with relative errors less than 0.003. These solutions form the kernel of multirate and multidimensional hydraulic, solute and thermal diffusion in fractured reservoirs.

Modeling of glycine solubility in aqueous HCl-MgCl2 system and its application in phase transition of glycine by changing media and supersaturation

NASA Astrophysics Data System (ADS)

Ansari, Ziaul Haque; Zeng, Yan; Zhang, Yan; Demopoulos, George P.; Li, Zhibao

2017-06-01

The solubility of glycine in HCl and HCl-MgCl2 solutions was measured from 283.15 to 343.15 K and found to increase with temperature and increase linearly with the concentration of HCl. The MSE model integrated in the OLI platform was modified by regressing the experimental and literature solubility data through the adjustment of the middle-range interaction parameters. After parameterization, the model can accurately calculate the solubility with the average absolute deviation lower than 3.5% and thus be able to predict supersaturation of glycine. Crystallization of different polymorphs of glycine in water, HCl, NaOH, MgCl2, and HCl-MgCl2 aqueous solutions was performed. The effects of medium, temperature, supersaturation, and time on the crystallization were investigated. It was found that only in the HCl solution the formation of single α-glycine phase was achieved under all the investigated temperature and holding time. α-glycine or its mixture with γ-glycine or C4H18N2O4·HCl was produced in systems other than HCl solution depending on the conditions.

TBARs distillation method: revision to minimize the interference from yellow pigments in meat products.

PubMed

Díaz, P; Linares, M B; Egea, M; Auqui, S M; Garrido, M D

2014-12-01

The aim was to study the effect of the incubation method and TBA reagent (concentration/solvent) on yellow pigment interference in meat products. Distillates from red sausage, sucrose, malondialdehyde and a mixture of sucrose-malondialdehyde were reacted with four different TBA solutions at five different temperature/time relations. Two TBA solutions were prepared at 20mM using 90% glacial acetic acid or 3.86% perchloric acid. In addition, an 80mM TBA solution was prepared using distilled water adjusted to pH4 and another using 0.8% TBA in distilled water. The temperature/time relations were: (1) 35min in a boiling water bath; (2) 70°C/30min; (3) 40°C/90min; (4) room temperature (r.t.) (24°C) in dark conditions for 20h; and (5) 60min in a boiling water bath. The results showed that aqueous or diluted acid solutions of TBA reagent and the application of 100°C for less than 1h provided the best conditions to minimize the presence of yellow pigments and maximize pink pigment formation in meat products. Copyright © 2014 Elsevier Ltd. All rights reserved.

Closed solutions to a differential-difference equation and an associated plate solidification problem.

PubMed

Layeni, Olawanle P; Akinola, Adegbola P; Johnson, Jesse V

2016-01-01

Two distinct and novel formalisms for deriving exact closed solutions of a class of variable-coefficient differential-difference equations arising from a plate solidification problem are introduced. Thereupon, exact closed traveling wave and similarity solutions to the plate solidification problem are obtained for some special cases of time-varying plate surface temperature.

Ice nucleation in nature: supercooling point (SCP) measurements and the role of heterogeneous nucleation.

PubMed

Wilson, P W; Heneghan, A F; Haymet, A D J

2003-02-01

In biological systems, nucleation of ice from a supercooled aqueous solution is a stochastic process and always heterogeneous. The average time any solution may remain supercooled is determined only by the degree of supercooling and heterogeneous nucleation sites it encounters. Here we summarize the many and varied definitions of the so-called "supercooling point," also called the "temperature of crystallization" and the "nucleation temperature," and exhibit the natural, inherent width associated with this quantity. We describe a new method for accurate determination of the supercooling point, which takes into account the inherent statistical fluctuations of the value. We show further that many measurements on a single unchanging sample are required to make a statistically valid measure of the supercooling point. This raises an interesting difference in circumstances where such repeat measurements are inconvenient, or impossible, for example for live organism experiments. We also discuss the effect of solutes on this temperature of nucleation. Existing data appear to show that various solute species decrease the nucleation temperature somewhat more than the equivalent melting point depression. For non-ionic solutes the species appears not to be a significant factor whereas for ions the species does affect the level of decrease of the nucleation temperature.

Conditions and mechanisms for the formation of nano-sized Delafossite (CuFeO2) at temperatures ≤90 °C in aqueous solution

NASA Astrophysics Data System (ADS)

John, Melanie; Heuss-Aßbichler, Soraya; Ullrich, Aladin

2016-02-01

In this study, we present the mechanism of CuFeO2 formation in aqueous solution at low temperatures ≤90 °C, using sulfate salts as reactants. Furthermore, we demonstrate the influence of experimental conditions (alkalization, reaction and ageing temperature and time) on the synthesized nanoparticles. In all cases, GR-SO4, a Fe(II-III) layered double hydroxysulphate (Fe2+4Fe3+2(OH)12·SO4) and Cu2O precipitate first. During further OH- supply GR-SO4 oxidizes and forms Fe10O14(OH)2, Cu2O and CuFeO2 crystals. Due to the high pH further CuFeO2 crystals grow at the cost of the unstable intermediate products. The reaction rate increases with increasing ageing temperature, reaction pH and, in particular, NaOH concentrations in the solution. As a result, highly crystalline CuFeO2 (3R and 2H polytypes) nanoparticles showing hexagonal morphology can be synthesized at 70 °C within 10 h or at 50 °C within 1 week. The formation of 2H polytype is favored by additional OH- supply during the pH-stat time and rather low temperatures.

Effects of open-air temperature on air temperature inside biological safety cabinet.

PubMed

Umemura, Masayuki; Shigeno, Katsuro; Yamamura, Keiko; Osada, Takashi; Soda, Midori; Yamada, Kiyofumi; Ando, Yuichi; Wakiya, Yoshifumi

2011-02-14

In Japan, biological safety cabinets (BSCs) are normally used by medical staff while handling antineoplastic agents. We have also set up a class II B2 BSC at the Division of Chemotherapy for Outpatients. The air temperature inside this BSC, however, decreases in winter. We assumed that this decrease is caused by the intake of open-air. Therefore, we investigated the effects of low open-air temperature on the BSC temperature and the time of admixtures of antineoplastic agents. The studies were conducted from January 1 to March 31, 2008. The outdoor air temperature was measured in the shade near the intake nozzle of the BSC and was compared with the BSC temperature. The correlation between the outdoor air temperature and the BSC temperature, the dissolution time of cyclophosphamide (CPA) and gemcitabine (GEM), and accurate weight measurement of epirubicin (EPI) solution were investigated for low and normal BSC temperatures. The BSC temperature was correlated with the open-air temperature for open-air temperatures of 5-20°C (p < 0.0001). The dissolution of CPA and GEM at these temperatures was significantly delayed as compared to that at 25°C (p < 0.01 and p < 0.0001, respectively). The weight measurement of EPI solution using a syringe method lacks accuracy because of its high coefficient of viscosity at low temperatures (p < 0.01). These results suggest that the BSC temperature decreases below room temperature in winter when air is drawn from outdoors. We showed that the BSC temperature affects the dissolution rate of antineoplastic agents. Further, we suggested that the BSC temperature drop might delay the affair of the admixtures of antineoplastic agents and increase the waiting time of outpatients for chemotherapy.

A Comparison Study: The New Extended Shelf Life Isopropyl Ester PMR Technology versus The Traditional Methyl Ester PMR Approach

NASA Technical Reports Server (NTRS)

Alston, William B.; Scheiman, Daniel A.; Sivko, Gloria S.

2005-01-01

Polymerization of Monomeric Reactants (PMR) monomer solutions and carbon cloth prepregs of PMR II-50 and VCAP-75 were prepared using both the traditional limited shelf life methanol based PMR approach and a novel extended shelf life isopropanol based PMR approach. The methyl ester and isopropyl ester based PMR monomer solutions and PMR prepregs were aged for up to four years at freezer and room temperatures. The aging products formed were monitored using high pressure liquid chromatography (HPLC). The composite processing flow characteristics and volatile contents of the aged prepregs were also correlated versus room temperature storage time. Composite processing cycles were developed and six ply cloth laminates were fabricated with prepregs after various extended room temperature storage times. The composites were then evaluated for glass transition temperature (Tg), thermal decomposition temperature (Td), initial flexural strength (FS) and modulus (FM), long term (1000 hours at 316 C) thermal oxidative stability (TOS), and retention of FS and FM after 1000 hours aging at 316 C. The results for each ester system were comparable. Freezer storage was found to prevent the formation of aging products for both ester systems. Room temperature storage of the novel isopropyl ester system increased PMR monomer solution and PMR prepreg shelf life by at least an order of magnitude while maintaining composite properties.

Behaviour of aqueous sulfamethizole solution and temperature effects in cold plasma oxidation treatment.

PubMed

Sokolov, Alexander; Louhi-Kultanen, Marjatta

2018-06-07

The increase in volume and variety of pharmaceuticals found in natural water bodies has become an increasingly serious environmental problem. The implementation of cold plasma technology, specifically gas-phase pulsed corona discharge (PCD), for sulfamethizole abatement was studied in the present work. It was observed that sulfamethizole is easily oxidized by PCD. The flow rate and pH of the solution have no significant effect on the oxidation. Treatment at low pulse repetition frequency is preferable from the energy efficiency point of view but is more time-consuming. The maximum energy efficiency was around 120 g/kWh at half-life and around 50 g/kWh at the end of the treatment. Increasing the solution temperature from room temperature to 50 °C led to a significant reaction retardation of the process and decrease in energy efficiency. The pseudo-first order reaction rate constant (k 1 ) grows with increase in pulse repetition frequency and does not depend on pH. By contrast, decreasing frequency leads to a reduction of the second order reaction rate constant (k 2 ). At elevated temperature of 50 °C, the k 1 , k 2 values decrease 2 and 2.9 times at 50 pps and 500 pps respectively. Lower temperature of 10 °C had no effect on oxidation efficiency compared with room temperature.

Cisplatin-Conjugated Porous Gelatin Particles: Assessment of Optimal Conditions for Binding and Release

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

Ohta, Shinichi, E-mail: junryuhei@yahoo.co.jp; Nitta, Norihisa; Sonoda, Akinaga

2010-08-15

This study was designed to evaluate the optimal conditions for binding cisplatin and porous gelatin particles (PGPs) and to establish in vivo drug release pharmacokinetics. PGPs were immersed in cisplatin solutions under different conditions: concentration, immersion time, and temperature. Thereafter, PGPs were washed in distilled water to remove uncombined cisplatin and were then freeze-dried. The platinum concentration (PC) in the PGPs was then measured. For the in vivo release test, 50 mg/kg of the cisplatin-conjugated PGPs was implanted subcutaneously in the abdominal region of two rabbits. PCs in the blood were measured at different time intervals. PCs significantly increased inmore » direct proportion to the concentration and immersion time (p < 0.01). Although PC increased at higher solution temperature, it was not a linear progression. For the in vivo release test, platinum was released from cisplatin-conjugated PGPs after 1 day, and the peak PC was confirmed 2 days after implantation. Platinum in the blood was detected until 7 days after implantation in one rabbit and 15 days after administration in the other rabbit. Platinum binding with PGPs increased with a higher concentration of cisplatin solution at a higher temperature over a longer duration of time. Release of cisplatin from cisplatin-conjugated PGPs was confirmed in vivo.« less

Impact of heat treatment on miscibility of proteins and disaccharides in frozen solutions.

PubMed

Izutsu, Ken-ichi; Yomota, Chikako; Okuda, Haruhiro; Kawanishi, Toru; Randolph, Theodore W; Carpenter, John F

2013-10-01

The purpose of this study was to elucidate the effect of heat treatment (annealing) on the miscibility of concentrated protein and disaccharide mixtures in the freezing segment of lyophilization. Frozen solutions containing a protein (e.g., recombinant human albumin, chicken egg lysozyme, bovine plasma immunoglobulin G, or a humanized IgG1k monoclonal antibody) and a non-reducing disaccharide (e.g., sucrose or trehalose) showed single thermal transitions of the solute mixtures (glass transition temperature of maximally freeze-concentrated solutes: T(g)(')) in their first heating scans. Heat treatment (e.g., -5 °C, 30 min) of some disaccharide-rich mixture frozen solutions at temperatures far above their T(g)(') induced two-step T(g)(') transitions in the subsequent scans, suggesting the separation of the solutes into concentrated protein-disaccharide mixture phase and disaccharide phase. Other frozen solutions showed a single transition of the concentrated solute mixture both before and after heat treatment. The apparent effects of the heat treatment temperature and time on the changes in thermal properties suggest molecular reordering of the concentrated solutes from a kinetically fixed mixture state to a more thermodynamically favorable state as a result of increased mobility. The implications of these phenomena on the quality of protein formulations are discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

A solvent replenishment solution for managing evaporation of biochemical reactions in air-matrix digital microfluidics devices.

PubMed

Jebrail, Mais J; Renzi, Ronald F; Sinha, Anupama; Van De Vreugde, Jim; Gondhalekar, Carmen; Ambriz, Cesar; Meagher, Robert J; Branda, Steven S

2015-01-07

Digital microfluidics (DMF) is a powerful technique for sample preparation and analysis for a broad range of biological and chemical applications. In many cases, it is desirable to carry out DMF on an open surface, such that the matrix surrounding the droplets is ambient air. However, the utility of the air-matrix DMF format has been severely limited by problems with droplet evaporation, especially when the droplet-based biochemical reactions require high temperatures for long periods of time. We present a simple solution for managing evaporation in air-matrix DMF: just-in-time replenishment of the reaction volume using droplets of solvent. We demonstrate that this solution enables DMF-mediated execution of several different biochemical reactions (RNA fragmentation, first-strand cDNA synthesis, and PCR) over a range of temperatures (4-95 °C) and incubation times (up to 1 h or more) without use of oil, humidifying chambers, or off-chip heating modules. Reaction volumes and temperatures were maintained roughly constant over the course of each experiment, such that the reaction kinetics and products generated by the air-matrix DMF device were comparable to those of conventional benchscale reactions. This simple yet effective solution for evaporation management is an important advance in developing air-matrix DMF for a wide variety of new, high-impact applications, particularly in the biomedical sciences.

A solvent replenishment solution for managing evaporation of biochemical reactions in air-matrix digital microfluidics devices

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

Jebrail, Mais J.; Renzi, Ronald F.; Sinha, Anupama

Digital microfluidics (DMF) is a powerful technique for sample preparation and analysis for a broad range of biological and chemical applications. In many cases, it is desirable to carry out DMF on an open surface, such that the matrix surrounding the droplets is ambient air. However, the utility of the air-matrix DMF format has been severely limited by problems with droplet evaporation, especially when the droplet-based biochemical reactions require high temperatures for long periods of time. We present a simple solution for managing evaporation in air-matrix DMF: just-in-time replenishment of the reaction volume using droplets of solvent. We demonstrate thatmore » this solution enables DMF-mediated execution of several different biochemical reactions (RNA fragmentation, first-strand cDNA synthesis, and PCR) over a range of temperatures (4–95 °C) and incubation times (up to 1 h or more) without use of oil, humidifying chambers, or off-chip heating modules. Reaction volumes and temperatures were maintained roughly constant over the course of each experiment, such that the reaction kinetics and products generated by the air-matrix DMF device were comparable to those of conventional benchscale reactions. As a result, this simple yet effective solution for evaporation management is an important advance in developing air-matrix DMF for a wide variety of new, high-impact applications, particularly in the biomedical sciences.« less

A solvent replenishment solution for managing evaporation of biochemical reactions in air-matrix digital microfluidics devices

DOE PAGES

Jebrail, Mais J.; Renzi, Ronald F.; Sinha, Anupama; ...

2014-10-01

Digital microfluidics (DMF) is a powerful technique for sample preparation and analysis for a broad range of biological and chemical applications. In many cases, it is desirable to carry out DMF on an open surface, such that the matrix surrounding the droplets is ambient air. However, the utility of the air-matrix DMF format has been severely limited by problems with droplet evaporation, especially when the droplet-based biochemical reactions require high temperatures for long periods of time. We present a simple solution for managing evaporation in air-matrix DMF: just-in-time replenishment of the reaction volume using droplets of solvent. We demonstrate thatmore » this solution enables DMF-mediated execution of several different biochemical reactions (RNA fragmentation, first-strand cDNA synthesis, and PCR) over a range of temperatures (4–95 °C) and incubation times (up to 1 h or more) without use of oil, humidifying chambers, or off-chip heating modules. Reaction volumes and temperatures were maintained roughly constant over the course of each experiment, such that the reaction kinetics and products generated by the air-matrix DMF device were comparable to those of conventional benchscale reactions. As a result, this simple yet effective solution for evaporation management is an important advance in developing air-matrix DMF for a wide variety of new, high-impact applications, particularly in the biomedical sciences.« less

Controlled chemical stabilization of polyvinyl precursor fiber, and high strength carbon fiber produced therefrom

DOEpatents

Naskar, Amit K.

2016-12-27

Method for the preparation of carbon fiber, which comprises: (i) immersing functionalized polyvinyl precursor fiber into a liquid solution having a boiling point of at least 60.degree. C.; (ii) heating the liquid solution to a first temperature of at least 25.degree. C. at which the functionalized precursor fiber engages in an elimination-addition equilibrium while a tension of at least 0.1 MPa is applied to the fiber; (iii) gradually raising the first temperature to a final temperature that is at least 20.degree. C. above the first temperature and up to the boiling point of the liquid solution for sufficient time to convert the functionalized precursor fiber to a pre-carbonized fiber; and (iv) subjecting the pre-carbonized fiber produced according to step (iii) to high temperature carbonization conditions to produce the final carbon fiber. Articles and devices containing the fibers, including woven and non-woven mats or paper forms of the fibers, are also described.

Method transfer from high-pressure liquid chromatography to ultra-high-pressure liquid chromatography. II. Temperature and pressure effects.

PubMed

Åsberg, Dennis; Samuelsson, Jörgen; Leśko, Marek; Cavazzini, Alberto; Kaczmarski, Krzysztof; Fornstedt, Torgny

2015-07-03

The importance of the generated temperature and pressure gradients in ultra-high-pressure liquid chromatography (UHPLC) are investigated and compared to high-pressure liquid chromatography (HPLC). The drug Omeprazole, together with three other model compounds (with different chemical characteristics, namely uncharged, positively and negatively charged) were used. Calculations of the complete temperature profile in the column at UHPLC conditions showed, in our experiments, a temperature difference between the inlet and outlet of 16 °C and a difference of 2 °C between the column center and the wall. Through van't Hoff plots, this information was used to single out the decrease in retention factor (k) solely due to the temperature gradient. The uncharged solute was least affected by temperature with a decrease in k of about 5% while for charged solutes the effect was more pronounced, with k decreases up to 14%. A pressure increase of 500 bar gave roughly 5% increase in k for the uncharged solute, while omeprazole and the other two charged solutes gave about 25, 20 and 15% increases in k, respectively. The stochastic model of chromatography was applied to estimate the dependence of the average number of adsorption/desorption events (n) and the average time spent by a molecule in the stationary phase (τs) on temperature and pressure on peak shape for the tailing, basic solute. Increasing the temperature yielded an increase in n and decrease in τs which resulted in less skew at high temperatures. With increasing pressure, the stochastic modeling gave interesting results for the basic solute showing that the skew of the peak increased with pressure. The conclusion is that pressure effects are more pronounced for both retention and peak shape than the temperature effects for the polar or charged compounds in our study. Copyright © 2015 Elsevier B.V. All rights reserved.

Dynamics of Magnesite Formation at Low-Temperature and High pCO2 in Aqueous Solution

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

Qafoku, Odeta; Dixon, David A.; Rosso, Kevin M.

2015-09-17

Like many metal carbonate minerals, despite conditions of supersaturation, precipitation of magnesite from aqueous solution is kinetically hindered at low temperatures, for reasons that remain poorly understood. The present study examines precipitation products from reaction of Mg(OH)2 in aqueous solutions saturated with supercritical CO2 at high pressures (90 atm and 110 atm) and low temperatures (35 °C and 50 °C). Traditional bulk characterization (X-ray diffraction) of the initial solid formed indicated the presence of hydrated magnesium carbonates (hydromagnesite and nesquehonite), thermodynamically metastable phases that were found to slowly react during ageing to the more stable anhydrous form, magnesite, at temperaturesmore » as low as 35 °C (135-140 days) and at a faster rate at 50 °C (56 days). Undetected by bulk measurements, detailed examination of the precipitates by scanning electron microscopy (SEM) showed that magnesite is present as a minor component at relatively early reaction times (7 days) at 50 °C. In addition to magnesite dominating the solid phases over time, we find that mangesite nucleation and growth occurs more quickly with increasing partial pressure of CO2, and in electrolyte solutions with high bicarbonate content. Furthermore, formation of magnesite was found to be enhanced in sulfate-rich solutions, compared to chloride-rich solutions. We speculate that much of this behavior is possibly due to sulfate serving as sink of protons generated during carbonation reactions. These results support the importance of integrating magnesite as an equilibrium phase in reactive transport calculations of the effects of carbon dioxide sequestration on subsurface formations at long time scales.« less

Development of practical decontamination process for the removal of uranium from gravel.

PubMed

Kim, Ilgook; Kim, Gye-Nam; Kim, Seung-Soo; Choi, Jong-Won

2018-01-01

In this study, a practical decontamination process was developed to remove uranium from gravel using a soil washing method. The effects of critical parameters including particle size, H 2 SO 4 concentration, temperature, and reaction time on uranium removal were evaluated. The optimal condition for two-stage washing of gravel was found to be particle size of 1-2 mm, 1.0 M H 2 SO 4 , temperature of 60°C, and reaction time of 3 h, which satisfied the required uranium concentration for self-disposal. Furthermore, most of the extracted uranium was removed from the waste solution by precipitation, implying that the treated solution can be reused as washing solution. These results clearly demonstrated that our proposed process can be indeed a practical technique to decontaminate uranium-polluted gravel.

Phase Transformation Temperatures and Solute Redistribution in a Quaternary Zirconium Alloy

NASA Astrophysics Data System (ADS)

Cochrane, C.; Daymond, M. R.

2018-05-01

This study investigates the phase stability and redistribution of solute during heating and cooling of a quaternary zirconium alloy, Excel (Zr-3.2Sn-0.8Mo-0.8Nb). Time-of-flight neutron diffraction data are analyzed using a novel Vegard's law-based approach to determine the phase fractions and location of substitutional solute atoms in situ during heating from room temperature up to 1050 °C. It is seen that this alloy exhibits direct nucleation of the β Zr phase from martensite during tempering, and stable retention of the β Zr phase to high temperatures, unlike other two-phase zirconium alloys. The transformation strains resulting from the α \\leftrightarrow β transformation are shown to have a direct impact on the development of microstructure and crystallographic texture.

Hybrid Raman/Brillouin-optical-time-domain-analysis-distributed optical fiber sensors based on cyclic pulse coding.

PubMed

Taki, M; Signorini, A; Oton, C J; Nannipieri, T; Di Pasquale, F

2013-10-15

We experimentally demonstrate the use of cyclic pulse coding for distributed strain and temperature measurements in hybrid Raman/Brillouin optical time-domain analysis (BOTDA) optical fiber sensors. The highly integrated proposed solution effectively addresses the strain/temperature cross-sensitivity issue affecting standard BOTDA sensors, allowing for simultaneous meter-scale strain and temperature measurements over 10 km of standard single mode fiber using a single narrowband laser source only.

Effect of Temperature and Fluid Flow on Dendrite Growth During Solidification of Al-3 Wt Pct Cu Alloy by the Two-Dimensional Cellular Automaton Method

NASA Astrophysics Data System (ADS)

Gu, Cheng; Wei, Yanhong; Liu, Renpei; Yu, Fengyi

2017-12-01

A two-dimensional cellular automaton-finite volume model was developed to simulate dendrite growth of Al-3 wt pct Cu alloy during solidification to investigate the effect of temperature and fluid flow on dendrite morphology, solute concentration distribution, and dendrite growth velocity. Different calculation conditions that may influence the results of the simulation, including temperature and flow, were considered. The model was also employed to study the effect of different undercoolings, applied temperature fields, and forced flow velocities on solute segregation and dendrite growth. The initial temperature and fluid flow have a significant impact on the dendrite morphologies and solute profiles during solidification. The release of energy is operated with solidification and results in the increase of temperature. A larger undercooling leads to larger solute concentration near the solid/liquid interface and solute concentration gradient at the same time-step. Solute concentration in the solid region tends to increase with the increase of undercooling. Four vortexes appear under the condition when natural flow exists: the two on the right of the dendrite rotate clockwise, and those on the left of the dendrite rotate counterclockwise. With the increase of forced flow velocity, the rejected solute in the upstream region becomes easier to be washed away and enriched in the downstream region, resulting in acceleration of the growth of the dendrite in the upstream and inhibiting the downstream dendrite growth. The dendrite perpendicular to fluid flow shows a coarser morphology in the upstream region than that of the downstream. Almost no secondary dendrite appears during the calculation process.

Efficacy of multipurpose solutions for rigid gas permeable lenses.

PubMed

Boost, Maureen; Cho, Pauline; Lai, Sindy

2006-09-01

The use of multipurpose solutions for cleaning and disinfecting rigid gas permeable lenses has replaced single purpose solutions, but there are no reports of the efficacy of these multipurpose solutions, or of the effects of storage conditions on their disinfecting capacities. This study investigated activity against four bacterial and two fungal species, and the effects of storage in a refrigerator, at room temperature, at elevated temperature in both dry and humid conditions and with exposure to sunlight. The disinfecting solutions were challenged with the micro-organisms initially upon opening and then at 2-weekly intervals up to 12 weeks after being stored under the different conditions. Solutions were opened daily to simulate use. One solution failed to meet Food and Drug Administration (FDA) criteria to reduce numbers of bacteria by three log dilutions and of fungi by one log dilution. Storage reduced activity of all solutions over the 12-week period, but not below the requirements of the FDA. Storage in the refrigerator tended to reduce disinfecting capacity more quickly. Multipurpose solutions for rigid gas permeable (RGP) lenses lose activity over the 3 months recommended time of use but remain satisfactory for use over this time in the conditions tested. Practitioners need to remind patients to replace their solutions regularly and should advise against storage in the refrigerator. Multipurpose solutions for RGP lenses have simplified cleaning and disinfecting processes and the current formulations have improved disinfecting capacity compared to former disinfecting solutions, which is particularly important for wearers of orthokeratology lenses.

Convective heat transfer in a measurement cell for scanning electrochemical microscopy.

PubMed

Novev, Javor K; Compton, Richard G

2016-11-21

Electrochemical experiments, especially those performed with scanning electrochemical microscopy (SECM), are often carried out without taking special care to thermostat the solution; it is usually assumed that its temperature is homogeneous and equal to the ambient. The present study aims to test this assumption via numerical simulations of the heat transfer in a particular system - the typical measurement cell for SECM. It is assumed that the temperature of the solution is initially homogeneous but different from that of its surroundings; convective heat transfer in the solution and the surrounding air is taken into account within the framework of the Boussinesq approximation. The hereby presented theoretical treatment indicates that an initial temperature difference of the order of 1 K dissipates with a characteristic time scale of ∼1000 s; the thermal equilibration is accompanied by convective flows with a maximum velocity of ∼10 -4 m s -1 ; furthermore, the temporal evolution of the temperature profile is influenced by the sign of the initial difference. These results suggest that, unless the temperature of the solution is rigorously controlled, convection may significantly compromise the interpretation of data from SECM and other electrochemical techniques, which is usually done on the basis of diffusion-only models.

Generalized reference fields and source interpolation for the difference formulation of radiation transport

NASA Astrophysics Data System (ADS)

Luu, Thomas; Brooks, Eugene D.; Szőke, Abraham

2010-03-01

In the difference formulation for the transport of thermally emitted photons the photon intensity is defined relative to a reference field, the black body at the local material temperature. This choice of reference field combines the separate emission and absorption terms that nearly cancel, thereby removing the dominant cause of noise in the Monte Carlo solution of thick systems, but introduces time and space derivative source terms that cannot be determined until the end of the time step. The space derivative source term can also lead to noise induced crashes under certain conditions where the real physical photon intensity differs strongly from a black body at the local material temperature. In this paper, we consider a difference formulation relative to the material temperature at the beginning of the time step, or in cases where an alternative temperature better describes the radiation field, that temperature. The result is a method where iterative solution of the material energy equation is efficient and noise induced crashes are avoided. We couple our generalized reference field scheme with an ad hoc interpolation of the space derivative source, resulting in an algorithm that produces the correct flux between zones as the physical system approaches the thick limit.

[Optimization on trehalose loading technique as protective conditioning for lyophilization of human platelets].

PubMed

Liu, Jing-Han; Zhou, Jun; Ouyang, Xi-Lin; Li, Xi-Jin; Lu, Fa-Qiang

2005-08-01

This study was aimed to further optimize trehalose loading technique including loading temperature, loading time, loading solution and loading concentration of trehalose, based on the established parameters. Loading efficiency in plasma was compared with that in buffer at 37 degrees C; the curves of intracellular trehalose concentration versus loading time at 37 degrees C and 16 degrees C were measured; curves of mean platelet volume (MPV) versus loading time and loading concentration were investigated and compared. According to results obtained, the loaing time, loading temperature, loading solution and trehalose concentration were ascertained for high loading efficiency of trehalose into human platelet. The results showed that the loading efficiency in plasma was markedly higher than that in buffer at 37 degrees C, the loading efficiency in plasma at 37 degrees C was significantly higher than that at 16 degrees C and reached 19.51% after loading for 4 hours, but 6.16% at 16 degrees C. MPV at 16 degrees C was increased by 43.2% than that at 37 degrees C, but had no distinct changes with loading time and loading concentration. In loading at 37 degrees C, MPV increased with loading time and loading concentration positively. Loading time and loading concentration displayed synergetic effect on MPV. MPV increased with loading time and concentration while trehalose loading concentration was above 50 mmol/L. It is concluded that the optimization parameters of trehalose loading technique are 37 degrees C (temperature), 4 hours (leading time), plasma (loading solution), 50 mmol/L (feasible trehalose concentration). The trehalose concentration can be adjusted to meet the requirement of lyophilization.

Theoretical study of heat transfer with moving phase-change interface in thawing of frozen food

NASA Astrophysics Data System (ADS)

Leung, M.; Ching, W. H.; Leung, D. Y. C.; Lam, G. C. K.

2005-02-01

A theoretical solution was obtained for a transient phase-change heat transfer problem in thawing of frozen food. In the physical model, a sphere originally at a uniform temperature below the phase-change temperature is suddenly immersed in a fluid at a temperature above the phase-change temperature. As the body temperature increases, the phase-change interface will be first formed on the surface. Subsequently, the interface will absorb the latent heat and move towards the centre until the whole body undergoes complete phase change. In the mathematical formulation, the nonhomogeneous problem arises from the moving phase-change interface. The solution in terms of the time-dependent temperature field was obtained by use of Green's function. A one-step Newton-Raphson method was specially designed to solve for the position of the moving interface to satisfy the interface condition. The theoretical results were compared with numerical results generated by a finite difference model and experimental measurements collected from a cold water thawing process. As a good agreement was found, the theoretical solution developed in this study was verified numerically and experimentally. Besides thawing of frozen food, there are many other practical applications of the theoretical solution, such as food freezing, soil freezing/thawing, metal casting and bath quenching heat treatment, among others.

A singlechip-computer-controlled conductivity meter based on conductance-frequency transformation

NASA Astrophysics Data System (ADS)

Chen, Wenxiang; Hong, Baocai

2005-02-01

A portable conductivity meter controlled by singlechip computer was designed. The instrument uses conductance-frequency transformation method to measure the conductivity of solution. The circuitry is simple and reliable. Another feature of the instrument is that the temperature compensation is realised by changing counting time of the timing counter. The theoretical based and the usage of temperature compensation are narrated.

Comparative rates of freeze-drying for lactose and sucrose solutions as measured by photographic recording, product temperature, and heat flux transducer.

PubMed

Chen, Rongjun; Slater, Nigel K H; Gatlin, Larry A; Kramer, Tony; Shalaev, Evgenyi Y

2008-01-01

Sublimation from lactose and sucrose solutions has been monitored by temperature measurement, visual observation, heat flux sensing and manometric measurements. Estimates of energy transfer rates to the subliming mass made from visual observations and heat flux measurements are in broad agreement, demonstrating for the first time that heat flux sensors can be used to monitor the progress of lyophilization in individual vials with low sample volumes. Furthermore, it is shown that under identical lyophilization conditions the initial rate of drying for lactose solutions is low with little water sublimation for up to 150 minutes, which contrasts markedly with the much faster initial rate of drying for sucrose solutions. Measurement of the initial heat flux between shelf and vial indicated a lower flux to a 10% lactose solution than to a 10% sucrose solution.

Heating 7.2 user`s manual

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

Childs, K.W.

1993-02-01

HEATING is a general-purpose conduction heat transfer program written in Fortran 77. HEATING can solve steady-state and/or transient heat conduction problems in one-, two-, or three-dimensional Cartesian, cylindrical, or spherical coordinates. A model may include multiple materials, and the thermal conductivity, density, and specific heat of each material may be both time- and temperature-dependent. The thermal conductivity may also be anisotropic. Materials may undergo change of phase. Thermal properties of materials may be input or may be extracted from a material properties library. Heat-generation rates may be dependent on time, temperature, and position, and boundary temperatures may be time- andmore » position-dependent. The boundary conditions, which may be surface-to-environment or surface-to-surface, may be specified temperatures or any combination of prescribed heat flux, forced convection, natural convection, and radiation. The boundary condition parameters may be time- and/or temperature-dependent. General gray-body radiation problems may be modeled with user-defined factors for radiant exchange. The mesh spacing may be variable along each axis. HEATING uses a runtime memory allocation scheme to avoid having to recompile to match memory requirements for each specific problem. HEATING utilizes free-form input. Three steady-state solution techniques are available: point-successive-overrelaxation iterative method with extrapolation, direct-solution, and conjugate gradient. Transient problems may be solved using any one of several finite-difference schemes: Crank-Nicolson implicit, Classical Implicit Procedure (CIP), Classical Explicit Procedure (CEP), or Levy explicit method. The solution of the system of equations arising from the implicit techniques is accomplished by point-successive-overrelaxation iteration and includes procedures to estimate the optimum acceleration parameter.« less

Heating 7. 2 user's manual

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

Childs, K.W.

1993-02-01

HEATING is a general-purpose conduction heat transfer program written in Fortran 77. HEATING can solve steady-state and/or transient heat conduction problems in one-, two-, or three-dimensional Cartesian, cylindrical, or spherical coordinates. A model may include multiple materials, and the thermal conductivity, density, and specific heat of each material may be both time- and temperature-dependent. The thermal conductivity may also be anisotropic. Materials may undergo change of phase. Thermal properties of materials may be input or may be extracted from a material properties library. Heat-generation rates may be dependent on time, temperature, and position, and boundary temperatures may be time- andmore » position-dependent. The boundary conditions, which may be surface-to-environment or surface-to-surface, may be specified temperatures or any combination of prescribed heat flux, forced convection, natural convection, and radiation. The boundary condition parameters may be time- and/or temperature-dependent. General gray-body radiation problems may be modeled with user-defined factors for radiant exchange. The mesh spacing may be variable along each axis. HEATING uses a runtime memory allocation scheme to avoid having to recompile to match memory requirements for each specific problem. HEATING utilizes free-form input. Three steady-state solution techniques are available: point-successive-overrelaxation iterative method with extrapolation, direct-solution, and conjugate gradient. Transient problems may be solved using any one of several finite-difference schemes: Crank-Nicolson implicit, Classical Implicit Procedure (CIP), Classical Explicit Procedure (CEP), or Levy explicit method. The solution of the system of equations arising from the implicit techniques is accomplished by point-successive-overrelaxation iteration and includes procedures to estimate the optimum acceleration parameter.« less

Photophysical properties of ortho-metalated monomeric and dimeric complexes containing rhodium(III) and iridium(III) metal centers

NASA Astrophysics Data System (ADS)

Marshall, Jason Alexander

Photophysical properties of dichloro-bridged dimers and monomeric tris complexes of the type [M(NC)2Cl]2 and M(NC)3, where NC refers to the ortho-metalating ligands 2-phenylpyridine (ppy), benzo[h]quinoline (bzq), or 2-(p-tolyl)pyridine (ptpy) and M is Rh(III) or Ir(III), were investigated. Excited-state emission of Rh(III) complexes are highly structured and independent of temperature from 4--100 K in glassy media, with long lifetimes (102 mus to ms). Emission is not observed from the pale yellow, fluid solutions of Rh(III) complexes at room temperature. Below 7K, decay kinetics are sensitive to temperature and are complicated, requiring multi-exponential fits in 4:1 EtOH/MeOH. The spectroscopic properties are consistent with the assignment of a lowest 3pipi* excited-state manifold perturbed by an admixture of higher-lying states possessing strong spin-orbit interactions. The complicated decays are attributed to spin-relaxation-limited behavior between spin-levels in the 3pipi* manifold. Deep yellow solutions of Ir(III) complexes in 4:1 EtOH/MeOH are observed to emit in both glassy media and in fluid solution, displaying severe changes in spectral shape as the glass softens which are not attributable to rigidochromic shifts. Low-temperature spectra are structured with emission origins in the range 496--520 nm whereas room-temperature emission of complexes in fluid solution are characteristically broad structureless bands with maxima redshifted from spectra measured in rigid media. Both the emission and the excited-state lifetimes display temperature dependence, with lifetimes in the microsecond to tens of microseconds range at 77 K, increasing by more than an order of magnitude as the temperature is decreased to 4 K. Each of these characteristic band shapes arises from separate components of the emission which have been time-resolved from the low-temperature spectrum. A long-lived, structured component of the emission, only observed in rigid media, has been assigned as 3pipi*. The spectroscopic properties of the short-lived component, observed in the time-resolved low-temperature emission spectrum and in the room-temperature fluid-solution emission spectrum, are consistent with a lowest 3MLCT excited state manifold.

Note: A microfluidic freezer based on evaporative cooling of atomized aqueous microdroplets

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

Song, Jin; Kim, Dohyun, E-mail: dohyun.kim@mju.ac.kr; Chung, Minsub

2015-01-15

We report for the first time water-based evaporative cooling integrated into a microfluidic chip for temperature control and freezing of biological solution. We opt for water as a nontoxic, effective refrigerant. Aqueous solutions are atomized in our device and evaporation of microdroplets under vacuum removes heat effectively. We achieve rapid cooling (−5.1 °C/s) and a low freezing temperature (−14.1 °C). Using this approach, we demonstrate freezing of deionized water and protein solution. Our simple, yet effective cooling device may improve many microfluidic applications currently relying on external power-hungry instruments for cooling and freezing.

Oil extraction from sheanut (Vitellaria paradoxa Gaertn C.F.) kernels assisted by microwaves.

PubMed

Nde, Divine B; Boldor, Dorin; Astete, Carlos; Muley, Pranjali; Xu, Zhimin

2016-03-01

Shea butter, is highly solicited in cosmetics, pharmaceuticals, chocolates and biodiesel formulations. Microwave assisted extraction (MAE) of butter from sheanut kernels was carried using the Doehlert's experimental design. Factors studied were microwave heating time, temperature and solvent/solute ratio while the responses were the quantity of oil extracted and the acid number. Second order models were established to describe the influence of experimental parameters on the responses studied. Under optimum MAE conditions of heating time 23 min, temperature 75 °C and solvent/solute ratio 4:1 more than 88 % of the oil with a free fatty acid (FFA) value less than 2, was extracted compared to the 10 h and solvent/solute ratio of 10:1 required for soxhlet extraction. Scanning electron microscopy was used to elucidate the effect of microwave heating on the kernels' microstructure. Substantial reduction in extraction time and volumes of solvent used and oil of suitable quality are the main benefits derived from the MAE process.

Influence of temperature on the rheological behavior of a new fucose-containing bacterial exopolysaccharide.

PubMed

Cruz, Madalena; Freitas, Filomena; Torres, Cristiana A V; Reis, Maria A M; Alves, Vítor D

2011-05-01

The effect of temperature on the rheology of a new fucose-containing extracellular polysaccharide (EPS) was evaluated. The steady state data revealed a shear-thinning behavior, with the viscosity being immediately recovered when the shear rate was decreased. The mechanical spectra indicated viscous solutions with entangled polymer molecules in the range of temperatures studied (from 15 °C to 65 °C). In addition, the Time-Temperature Superposition principle was successfully applied and the Cox-Merz rule was valid, reinforcing the idea of a thermorheologically simple behavior for the EPS in aqueous solution. Furthermore, the viscous and viscoelastic properties at 25 °C were maintained after consecutive heating and cooling cycles, indicating a good thermal stability under temperature fluctuations. Copyright © 2011 Elsevier B.V. All rights reserved.

A method of calculating quartz solubilities in aqueous sodium chloride solutions

USGS Publications Warehouse

Fournier, R.O.

1983-01-01

The aqueous silica species that form when quartz dissolves in water or saline solutions are hydrated. Therefore, the amount of quartz that will dissolve at a given temperature is influenced by the prevailing activity of water. Using a standard state in which there are 1,000 g of water (55.51 moles) per 1,000 cm3 of solution allows activity of water in a NaCl solution at high temperature to be closely approximated by the effective density of water, pe, in that solution, i.e. the product of the density of the NaCl solution times the weight fraction of water in the solution, corrected for the amount of water strongly bound to aqueous silica and Na+ as water of hydration. Generally, the hydration of water correction is negligible. The solubility of quartz in pure water is well known over a large temperature-pressure range. An empirical formula expresses that solubility in terms of temperature and density of water and thus takes care of activity coefficient and pressure-effect terms. Solubilities of quartz in NaCl solutions can be calculated by using that equation and substituting pe, for the density of pure water. Calculated and experimentally determined quartz solubilities in NaCl solutions show excellent agreement when the experiments were carried out in non-reactive platinum, gold, or gold plus titanium containers. Reactive metal containers generally yield dissolved silica concentrations higher than calculated, probably because of the formation of metal chlorides plus NaOH and H2. In the absence of NaOH there appears to be no detectable silica complexing in NaCl solutions, and the variation in quartz solubility with NaCl concentration at constant temperature can be accounted for entirely by variations in the activity of water. The average hydration number per molecule of dissolved SiO2 in liquid water and NaCl solutions decreases from about 2.4 at 200??C to about 2.1 at 350??C. This suggests that H4SiO4 may be the dominant aqueous silica species at 350??C, but other polymeric forms become important at lower temperatures. ?? 1983.

Photoacoustic-Based-Close-Loop Temperature Control for Nanoparticle Hyperthermia.

PubMed

Xiaohua, Feng; Fei, Gao; Yuanjin, Zheng

2015-07-01

Hyperthermia therapy requires tight temperature control to achieve selective killing of cancerous tissue with minimal damage on surrounding healthy tissues. To this end, accurate temperature monitoring and subsequent heating control are critical. However, an economic, portable, and real-time temperature control solution is currently lacking. To bridge this gap, we present a novel portable close-loop system for hyperthermia temperature control, in which photoacoustic technique is proposed for noninvasive real-time temperature measurement. Exploiting the high sensitivity of photoacoustics, the temperature is monitored with an accuracy of around 0.18 °C and then fed back to a controller implemented on field programmable gate array (FPGA) for temperature control. Dubbed as portable hyperthermia feedback controller (pHFC), it stabilizes the temperature at preset values by regulating the hyperthermia power with a proportional-integral-derivative (PID) algorithm; and to facilitate digital implementation, the pHFC further converts the PID output into switching values (0 and 1) with the pulse width modulation (PWM) algorithm. Proof-of-concept hyperthermia experiments demonstrate that the pHFC system is able to bring the temperature from baseline to predetermined value with an accuracy of 0.3° and a negligible temperature overshoot. The pHFC can potentially be translated to clinical applications with customized hyperthermia system design. This paper can facilitate future efforts in seamless integration of close-loop temperature control solution and various clinical hyperthermia systems.

The Effect of Solution Thermal History on Chicken Egg White Lysozyme Nucleation

NASA Technical Reports Server (NTRS)

Burke, Michael W.; Judge, Russell A.; Pusey, Marc L.

2001-01-01

Proteins are highly flexible molecules and often exhibit defined conformational changes in response to changes in the ambient temperature. Chicken egg white lysozyme has been previously shown to undergo an apparent structural change when warmed above the tetragonal/orthorhombic phase transition temperature. This is reflected by a change in the habit of the tetragonal and orthorhombic crystals so formed. In this study, we show that possible conformational changes induced by heating are stable and apparently non-reversible by simple cooling. Exposure of protein solutions to temperatures above the phase change transition temperature, before combining with precipitant solution to begin crystallization, reduces final crystal numbers. Protein that is briefly warmed to 37 C, then cooled shows no sign of reversal to the unheated nucleation behavior even after storage for four weeks at 4 C. The change in nucleation behavior of tetragonal lysozyme crystals, attributed to a structural shift, occurs faster the greater the exposure to temperature above the equi-solubility point for the two phases. Heating for 2 hours at 48 C reduces crystal numbers by 20 fold in comparison to the same solution heated for the same time at 30 C. Thermal treatment of solutions is therefore a possible tool to reduce crystal numbers and increase crystal size. The effects of a protein's previous thermal history are now shown to be a potentially critical factor in subsequent macromolecule crystal nucleation and growth studies.

The Effect of Solution Thermal History on Chicken Egg White Lysozyme Nucleation

NASA Technical Reports Server (NTRS)

Burke, Michael W.; Judge, Russell A.; Pusey, Marc L.; Rose, M. Franklin (Technical Monitor)

2000-01-01

Proteins are highly flexible molecules and often exhibit defined conformational changes in response to changes in the ambient temperature. Chicken egg white lysozyme has been previously shown to undergo an apparent structural change when warmed above the tetragonal/orthorhombic phase transition temperature. This is reflected by a change in the habit of the tetragonal and orthorhombic crystals so formed. In this study we show that possible conformational changes induced by heating are stable and apparently non- reversible by simple cooling. Exposure of protein solutions to temperatures above the phase change transition temperature, before combining with precipitant solution to begin crystallization, reduces final crystal numbers. Protein that is briefly warmed to 37 C, then cooled shows no sign of reversal to the unheated nucleation behavior even after storage for 4 weeks at 4 C. The change in nucleation behavior of tetragonal lysozyme crystals, attributed to a structural shift, occurs faster the greater the exposure to temperature above the equi-solubility point for the two phases. Heating for 2 h at 48 C reduces crystal numbers by 20 fold in comparison to the same solution heated for the same time at 30 C. Thermal treatment of solutions is therefore a possible tool to reduce crystal numbers and increase crystal size. The effects of a protein's previous thermal history are now shown to be a potentially critical factor in subsequent macromolecule crystal nucleation and growth studies.

Constrained Self-adaptive Solutions Procedures for Structure Subject to High Temperature Elastic-plastic Creep Effects

NASA Technical Reports Server (NTRS)

Padovan, J.; Tovichakchaikul, S.

1983-01-01

This paper will develop a new solution strategy which can handle elastic-plastic-creep problems in an inherently stable manner. This is achieved by introducing a new constrained time stepping algorithm which will enable the solution of creep initiated pre/postbuckling behavior where indefinite tangent stiffnesses are encountered. Due to the generality of the scheme, both monotone and cyclic loading histories can be handled. The presentation will give a thorough overview of current solution schemes and their short comings, the development of constrained time stepping algorithms as well as illustrate the results of several numerical experiments which benchmark the new procedure.

Solution of the equation of heat conduction with time dependent sources: Programmed application to planetary thermal history

NASA Technical Reports Server (NTRS)

Conel, J. E.

1975-01-01

A computer program (Program SPHERE) solving the inhomogeneous equation of heat conduction with radiation boundary condition on a thermally homogeneous sphere is described. The source terms are taken to be exponential functions of the time. Thermal properties are independent of temperature. The solutions are appropriate to studying certain classes of planetary thermal history. Special application to the moon is discussed.

Control of enzymatic browning in apple slices by using ascorbic acid under different conditions.

PubMed

el-Shimi, N M

1993-01-01

Control of phenol oxidase activity in apple slices by the use of ascorbic acid at different pH values, temperature and time of incubation was investigated. The enzyme was almost inactivated at 1% and 1.5% ascorbic acid. Ascorbic acid solution (1%) caused a remarkable inhibition with the increasing acidity up to pH = 1. Heating treatments for apple slices dipped in 1% ascorbic acid caused a reduction of enzymatic browning, optimum temperature for inactivation of the enzyme was between 60-70 degrees C for 15 minutes. Increasing the time of dipping apple slices in 1% ascorbic acid solutions and at different pH values reduce phenolase activity.

Effect of temperature on hydration kinetics and polymerization of tricalcium silicate in stirred suspensions of CaO-saturated solutions

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

Grant, Steven A.; Boitnott, Ginger E.; Korhonen, Charles J.

2006-04-15

Tricalcium silicate was hydrated at 274, 278, 283, 298, and 313 K in stirred suspensions of saturated CaO solutions under a nitrogen-gas atmosphere until the end of deceleratory period. The suspension conductivities and energy flows were measured continuously. The individual reaction rates for tricalcium silicate dissolution, calcium silicate hydrate precipitation, and calcium hydroxide precipitation were calculated from these measurements. The results suggest that the proportion of tricalcium silicate dissolved was determined by the rate of tricalcium silicate dissolution and the time to very rapid calcium hydroxide precipitation. The time to very rapid calcium hydroxide precipitation was more sensitive to changesmore » in temperature than was the rate of tricalcium silicate dissolution, so that the proportion of tricalcium silicate hydration dissolved by the deceleratory period increased with decreasing temperature. The average chain length of the calcium silicate hydrate ascertained by magic-angle spinning nuclear magnetic resonance spectroscopy increased with increasing temperature.« less

Relationship of mechanical characteristics and microstructural features to the time-dependent edge notch sensitivity of inconel 718 sheet

NASA Technical Reports Server (NTRS)

Wilson, D. J.

1971-01-01

Time-dependent notch sensitivity of Inconel 718 sheet was observed at 900 F to 1200 F (482 - 649 C). It occurred when edge-notched specimens were loaded below the yield strength and smooth specimen tests showed that small amounts of creep consumed large rupture life fractions. The severity of the notch sensitivity was reduced by decreasing the solution temperature, increasing the time and/or temperature of aging and increasing the test temperature to 1400 F (760 C). Elimination of time-dependent notch sensitivity correlated with a change in dislocation motion mechanism from shearing to by-passing precipitate particles.

The study of dielectric relaxation in aqueous carbohydrates solutions using time domain reflectometry technique

NASA Astrophysics Data System (ADS)

Hudge, Pravin G.; Lokhande, Milind P.; Kumbharkhane, Ashok C.

2012-09-01

Complex permittivity spectra of aqueous solutions of monosaccharide ( d-glucose) and disaccharides ( d-sucrose) in the frequency range from 10 MHz to 30 GHz at various concentrations and temperatures have been determined using time domain reflectometry technique. The complex dielectric permittivity spectrum of d-glucose and d-sucrose in water shows Cole-Davidson type behaviour. Dielectric constant (ɛ0) and relaxation time (τ), Kirkwood correlation factor, activation enthalpy and entropy parameters have been determined.

The unidirectional motion of two heat-conducting liquids in a flat channel

NASA Astrophysics Data System (ADS)

Andreev, V. K.; Cheremnykh, E. N.

2017-10-01

The unidirectional motion of two viscous incompressible liquids in a flat channel is studied. Liquids contact on a flat interface. External boundaries are fixed solid walls, on which the non-stationary temperature gradients are given. The motion is induced by a joint action of thermogravitational and thermocapillary forces and given total non - stationary fluid flow rate in layers. The corresponding initial boundary value problem is conjugate and inverse because the pressure gradients along axes channel have to be determined together with the velocity and temperature field. For this problem the exact stationary solution is found and a priori estimates of non - stationary solutions are obtained. In Laplace images the solution of the non - stationary problem is found in quadratures. It is proved, that the solution converges to a steady regime with time, if the temperature on the walls and the fluid flow rate are stabilized. The numerical calculations for specific liquid media good agree with the theoretical results.

Time-dependent edge notch sensitivity of Inconel 718 sheet in the temperature range 900 to 1400 F (482 to 760 C)

NASA Technical Reports Server (NTRS)

Wilson, D. J.

1972-01-01

Time-dependent notch sensitivity of Inconel 718 sheet occurred at 900 to 1200 F when notched specimens were loaded below the yield strength, and tests on smooth specimens showed that small amounts of creep consumed large fractions of creep-rupture life. The severity of the notch sensitivity decreased with decreasing solution treatment temperature and increasing time and/or temperature of the aging treatment. Elimination of the notch sensitivity was correlated with a change in the dislocation mechanism from shearing to by-passing precipitate particles.

Excited state intramolecular charge transfer reaction in nonaqueous electrolyte solutions: Temperature dependence

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

Pradhan, Tuhin; Gazi, Harun Al Rasid; Biswas, Ranjit

2009-08-07

Temperature dependence of the excited state intramolecular charge transfer reaction of 4-(1-azetidinyl)benzonitrile (P4C) in ethyl acetate (EA), acetonitrile (ACN), and ethanol at several concentrations of lithium perchlorate (LiClO{sub 4}) has been investigated by using the steady state and time resolved fluorescence spectroscopic techniques. The temperature range considered is 267-343 K. The temperature dependent spectral peak shifts and reaction driving force (-{Delta}G{sub r}) in electrolyte solutions of these solvents can be explained qualitatively in terms of interaction between the reactant molecule and ion-atmosphere. Time resolved studies indicate that the decay kinetics of P4C is biexponential, regardless of solvents, LiClO{sub 4} concentrations,more » and temperatures considered. Except at higher electrolyte concentrations in EA, reaction rates in solutions follow the Arrhenius-type temperature dependence where the estimated activation energy exhibits substantial electrolyte concentration dependence. The average of the experimentally measured activation energies in these three neat solvents is found to be in very good agreement with the predicted value based on data in room temperature solvents. While the rate constant in EA shows a electrolyte concentration induced parabolic dependence on reaction driving force (-{Delta}G{sub r}), the former in ethanol and ACN increases only linearly with the increase in driving force (-{Delta}G{sub r}). The data presented here also indicate that the step-wise increase in solvent reorganization energy via sequential addition of electrolyte induces the ICT reaction in weakly polar solvents to crossover from the Marcus inverted region to the normal region.« less

Marangoni Flow Induced Evaporation Enhancement on Binary Sessile Drops.

PubMed

Chen, Pin; Harmand, Souad; Ouenzerfi, Safouene; Schiffler, Jesse

2017-06-15

The evaporation processes of pure water, pure 1-butanol, and 5% 1-butanol aqueous solution drops on heated hydrophobic substrates are investigated to determine the effect of temperature on the drop evaporation behavior. The evolution of the parameters (contact angle, diameter, and volume) during evaporation measured using a drop shape analyzer and the infrared thermal mapping of the drop surface recorded by an infrared camera were used in investigating the evaporation process. The pure 1-butanol drop does not show any thermal instability at different substrate temperatures, while the convection cells created by the thermal Marangoni effect appear on the surface of the pure water drop from 50 °C. Because 1-butanol and water have different surface tensions, the infrared video of the 5% 1-butanol aqueous solution drop shows that the convection cells are generated by the solutal Marangoni effect at any substrate temperature. Furthermore, when the substrate temperature exceeds 50 °C, coexistence of the thermal and solutal Marangoni flows is observed. By analyzing the relation between the ratio of the evaporation rate of pure water and 1-butanol aqueous solution drops and the Marangoni number, a series of empirical equations for predicting the evaporation rates of pure water and 1-butanol aqueous solution drops at the initial time as well as the equations for the evaporation rate of 1-butanol aqueous solution drop before the depletion of alcohol are derived. The results of these equations correspond fairly well to the experimental data.

Contribution of extracellular ice formation and the solution effects to the freezing injury of PC-3 cells suspended in NaCl solutions.

PubMed

Takamatsu, Hiroshi; Zawlodzka, Sylwia

2006-08-01

The mechanism of cell injury during slow freezing was examined using PC-3 human prostate adenocarcinoma cells suspended in NaCl solutions. The objective was to evaluate contribution of extracellular ice and the 'solution effects' to freezing injury separately. The solution effects that designate the influence of elevated concentration were evaluated from a pseudo-freezing experiment, where cells were subjected to the milieu that simulated a freeze-thaw process by changing the NaCl concentration and the temperature at the same time. The effect of extracellular ice formation on cell injury was then estimated from the difference in cell survival between the pseudo-freezing experiment and a corresponding freezing experiment. When cells were frozen to a relatively higher freezing temperature at -10 degrees C, about 30% of cells were damaged mostly due to extracellular ice formation, because the concentration increase without ice formation to 2.5-M NaCl, i.e., the equilibrium concentration at -10 degrees C, had no effect on cell survival. In contrast, in the case of the lower freezing temperature at -20 degrees C, about 90% of cells were injured by both effects, particularly 60-80% by the solution effects among them. The present results suggested that the solution effects become more crucial to cell damage during slow freezing at lower temperatures, while the effect of ice is limited to some extent.

Spatio-temporal droplet size statistics in developing spray of starchy solution

NASA Astrophysics Data System (ADS)

Naz, Muhammad Yasin; Sulaiman, Shaharin Anwar; Ariwahjoedi, Bambang

2015-07-01

In the given research, the spray jet breakup of a modified starch solution was studied as a function of jet injection time and nozzle orifice diameter. The starch-urea-borax solution was prepared and tested with three axisymmetric full cone nozzles at service temperature of 80°C and the injection pressure of 5 bar. It is worth mentioning that no jet breakup was seen below these temperature and pressure values. The imaging studies on the time based spray evolution revealed monotonic increase in both; spray cone angle and tip penetration with an increase in injection time form 0-300 mm. Hereinafter, both parameters exhibited constants value over injection time. Phase Doppler Anemometry (PDA) measurements of the droplet size revealed significant decrease in the Sauter Mean Diameter (SMD) along the spray centerline. However, a steady decrease in SMD was seen towards the spray boundary. For fixed injection time of 300 ms, the overall SMD was decreased from 112 to 71 µm at 60 mm downstream, from 102 to 64 µm at 100 mm downstream and from 85 to 61 µm at 140 mm downstream with an increase in orifice diameter from 1.19 to 1.59 mm.

Viking Afterbody Heating Computations and Comparisons to Flight Data

NASA Technical Reports Server (NTRS)

Edquist, Karl T.; Wright, Michael J.; Allen, Gary A., Jr.

2006-01-01

Computational fluid dynamics predictions of Viking Lander 1 entry vehicle afterbody heating are compared to flight data. The analysis includes a derivation of heat flux from temperature data at two base cover locations, as well as a discussion of available reconstructed entry trajectories. Based on the raw temperature-time history data, convective heat flux is derived to be 0.63-1.10 W/cm2 for the aluminum base cover at the time of thermocouple failure. Peak heat flux at the fiberglass base cover thermocouple is estimated to be 0.54-0.76 W/cm2, occurring 16 seconds after peak stagnation point heat flux. Navier-Stokes computational solutions are obtained with two separate codes using an 8- species Mars gas model in chemical and thermal non-equilibrium. Flowfield solutions using local time-stepping did not result in converged heating at either thermocouple location. A global time-stepping approach improved the computational stability, but steady state heat flux was not reached for either base cover location. Both thermocouple locations lie within a separated flow region of the base cover that is likely unsteady. Heat flux computations averaged over the solution history are generally below the flight data and do not vary smoothly over time for both base cover locations. Possible reasons for the mismatch between flight data and flowfield solutions include underestimated conduction effects and limitations of the computational methods.

Viking Afterbody Heating Computations and Comparisons to Flight Data

NASA Technical Reports Server (NTRS)

Edquist, Karl T.; Wright, Michael J.; Allen, Gary A., Jr.

2006-01-01

Computational fluid dynamics predictions of Viking Lander 1 entry vehicle afterbody heating are compared to flight data. The analysis includes a derivation of heat flux from temperature data at two base cover locations, as well as a discussion of available reconstructed entry trajectories. Based on the raw temperature-time history data, convective heat flux is derived to be 0.63-1.10 W/sq cm for the aluminum base cover at the time of thermocouple failure. Peak heat flux at the fiberglass base cover thermocouple is estimated to be 0.54-0.76 W/sq cm, occurring 16 seconds after peak stagnation point heat flux. Navier-Stokes computational solutions are obtained with two separate codes using an 8-species Mars gas model in chemical and thermal non-equilibrium. Flowfield solutions using local time-stepping did not result in converged heating at either thermocouple location. A global time-stepping approach improved the computational stability, but steady state heat flux was not reached for either base cover location. Both thermocouple locations lie within a separated flow region of the base cover that is likely unsteady. Heat flux computations averaged over the solution history are generally below the flight data and do not vary smoothly over time for both base cover locations. Possible reasons for the mismatch between flight data and flowfield solutions include underestimated conduction effects and limitations of the computational methods.

Characteristics of nano-sized yttria powder synthesized by a polyvinyl alcohol solution route at low temperature.

PubMed

Lee, Sang-Jin; Jung, Choong-Hwan

2012-01-01

Nano-sized yttria (Y2O3) powders were successfully synthesized at a low temperature of 400 degrees C by a simple polymer solution route. PVA polymer, as an organic carrier, contributed to an atom-scale homogeneous precursor gel and it resulted in fully crystallized, nano-sized yttria powder with high specific surface area through the low temperature calcination. In this process, the content of PVA, calcination temperature and heating time affected the microstructure and crystallization behavior of the powders. The development of crystalline phase and the final particle size were strongly dependant on the oxidation reaction from the polymer burn-out step and the PVA content. In this paper, the PVA solution technique for the fabrication of nano-sized yttria powders is introduced. The effects of PVA content and holding time on the powder morphology and powder specific surface area are also studied. The characterization of the synthesized powders is examined by using XRD, DTA/TG, SEM, TEM and nitrogen gas adsorption. The yttria powder synthesized from the PVA content of 3:1 ratio and calcined at 400 degrees C had a crystallite size of about 20 nm or less with a high surface areas of 93.95-120.76 m2 g(-1).

Study of Colloidal Gold Synthesis Using Turkevich Method

NASA Astrophysics Data System (ADS)

Rohiman, Asep; Anshori, Isa; Surawijaya, Akhmadi; Idris, Irman

2011-12-01

The synthesis of colloidal gold or Au-nanoparticles (Au-NPs) by reduction of chloroauric acid (HAuCl4) with sodium citrate was done using Turkevich method. We prepare HAuCl4 solution by dissolving gold wires (99.99%) into aqua regia solution. To initiate the Au-NPs synthesis 0.17 ml of 1 % chloroauric acid solution was heated to the boiling point and then 10 ml of 1 % sodium citrate was added to the boiling solution with a constant stirring in order to maintain a homogenous solution. A color of faint gray was observed in the solution approximately one minute and in a period of 2-3 minutes later, it further darkened to deep wine and red color. It showed that the gold solution has reduced to Au-NPs. The effect of process temperature on the size of Au-NPs prepared by sodium citrate reduction has also been investigated. With increasing temperature of Au-NPs synthesis, smaller-size Au-NPs were obtained. The higher temperatures shorten the time needed to achieve activation energy for reduction process. The resulting Au-NPs has been characterized by scanning Electron Microscope (SEM), showing the size of Au-NPs average diameter is ˜20-27 nm. The resulting colloidal gold will be used as catalyst for Si nanowires growth using VLS method.

Low-cost and low maintenance preservation of Agaricus brasiliensis cultures.

PubMed

Maia, Scheila C; Toledo, Rômulo C C; Almeida, Ana Paula M M; da Silva, Romildo; Rinker, Danny Lee; Dias, Eustáquio S

2012-06-01

Agaricus brasiliensis cultures quickly lose viability when stored at cool temperatures, even for a short period of time. We evaluated several low-cost preservation methods using varied substrates, preservation solutions, and storage temperatures. Agaricus brasiliensis was intolerant to freezing temperatures, making liquid nitrogen use and deep-freezing methods impossible for its preservation. The best preservation conditions for the A. brasiliensis CS1 strain tested in this study were obtained by using rice as substrate and water as preservation solution, with storage at room temperature or when using soil, mushroom cultivation compost, or rice and stored at 10 °C without preservation solution. Those cultures that were reactivated showed the same productivity attributes as the control. In addition, no effect on productivity or biological efficiency was observed through successive subculturing of the strain (CS1). Parboiled rice was successfully used for other A. brasiliensis strains (CS2, CS5, CS7, CS9, and CS10), and also for Pleurotus ostreatus, P. sajor-caju, and Lentinula edodes.

A diurnal animation of thermal images from a day-night pair

USGS Publications Warehouse

Watson, K.

2000-01-01

Interpretation of thermal images is often complicated because the physical property information is contained in both the spatial and temporal variations of the data and thermal models are necessary to extract and display this information. A linearized radiative transfer solution to the surface flux has been used to derive a function that is invariant with respect to thermal inertia. This relationship makes it possible to predict the temperature variation at any time in the diurnal cycle using only two distinct measurements (e.g., noon and midnight). An animation can then be constructed from a pair of day-night images to view both the spatial and temporal temperature changes throughout the diurnal cycle. A more complete solution for the invariant function, using the method of Laplace transforms and based on the linearized solution, was introduced. These results indicate that the linear model does not provide a sufficiently accurate estimate. Using standard conditions (latitude 30??, solar declination 0??, acquisition times at noon and midnight), this new relationship was used to predict temperature throughout the diurnal cycle to an rms error of 0.2??C, which is close to the system noise of most thermal scanners. The method was further extended to include the primary effects of topographic slope with similar accuracy. The temperature was computed at 48 equally spaced times in the diurnal cycle with this algorithm using a co-registered day and night TIMS (Thermal Infrared Multispectral Scanner) data pair (330 pixels, 450 lilies) acquired of the Carlin, Nevada, area and a co-registered DEM (Digital Elevation Model). (Any reader can view the results by downloading the animation file from an identified tip site). The results illustrate the power of animation to display subtle temporal and spatial temperature changes, which can provide clues to structural controls and material property differences. This 'visual change' approach could significantly increase the use of thermal data for environmental, hazard, and resource studies. Published by Elsevier Science Inc., 2000.A linearized radiative transfer solution of determining the surface flux is proposed to predict the temperature variation at any time in the diurnal cycle using only two distinct measurements. An animation is constructed from a pair of day-night images to view the spatial and temporal temperature changes throughout the diurnal cycle. The results illustrate the effectiveness of animation to display subtle temporal and spatial temperature changes, which can provide clues to structural controls and material property differences.

The effect of structural properties on rheological behaviour of starches in binary dimethyl sulfoxide-water solutions.

PubMed

Ptaszek, Anna; Ptaszek, Paweł; Dziubiński, Marek; Grzesik, N Mirosław; Liszka-Skoczylas, Marta

2017-01-01

This research study analysed the rheological properties of potato amylose and potato amylopectin in binary solutions of the following water and dimethyl sulfoxide concentrations: 90% DMSO (1), 80% DMSO (2) and 50% DMSO (3), with preparation methodology involving the dissolution at the temperature of 98°C. The studies of dynamic light scattering on the biopolymer coils and the determination of main relaxation times of the solutions were carried out. For the amylose solutions, the fast relaxation phenomena are predominant. The results of the quality tests of the hysteresis loop showed, that the amylose solutions in the solvents (1) and (2) are rheologically stable and shear-thickened. The amylose solutions in solvents (3) reveal oscillatory alterations of viscosity in the time. Amylopectin solutions are characterized by 80% share of slow relaxation phenomena, very low diffusion coefficients and hydrodynamic radii in the range of 2000 nm. The amylopectin solutions are rheologically unstable.

Aluminum Target Dissolution in Support of the Pu-238 Program

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

McFarlane, Joanna; Benker, Dennis; DePaoli, David W

2014-09-01

Selection of an aluminum alloy for target cladding affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the caustic dissolution step, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. We present a study to maximize dissolution of aluminum metal alloy, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as a function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. These datamore » have been compared with published calculations of aluminum phase diagrams. Temperature logging during the transients has been investigated as a means to generate kinetic and mass transport data on the dissolution process. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.« less

Thermal stresses due to cooling of a viscoelastic oceanic lithosphere

USGS Publications Warehouse

Denlinger, R.P.; Savage, W.Z.

1989-01-01

Instant-freezing methods inaccurately predict transient thermal stresses in rapidly cooling silicate glass plates because of the temperature dependent rheology of the material. The temperature dependent rheology of the lithosphere may affect the transient thermal stress distribution in a similar way, and for this reason we use a thermoviscoelastic model to estimate thermal stresses in young oceanic lithosphere. This theory is formulated here for linear creep processes that have an Arrhenius rate dependence on temperature. Our results show that the stress differences between instant freezing and linear thermoviscoelastic theory are most pronounced at early times (0-20 m.y. when the instant freezing stresses may be twice as large. The solutions for the two methods asymptotically approach the same solution with time. A comparison with intraplate seismicity shows that both methods underestimate the depth of compressional stresses inferred from the seismicity in a systematic way. -from Authors

Exact solutions for unsteady free convection flow over an oscillating plate due to non-coaxial rotation.

PubMed

Mohamad, Ahmad Qushairi; Khan, Ilyas; Ismail, Zulkhibri; Shafie, Sharidan

2016-01-01

Non-coaxial rotation has wide applications in engineering devices, e.g. in food processing such as mixer machines and stirrers with a two-axis kneader, in cooling turbine blades, jet engines, pumps and vacuum cleaners, in designing thermal syphon tubes, and in geophysical flows. Therefore, this study aims to investigate unsteady free convection flow of viscous fluid due to non-coaxial rotation and fluid at infinity over an oscillating vertical plate with constant wall temperature. The governing equations are modelled by a sudden coincidence of the axes of a disk and the fluid at infinity rotating with uniform angular velocity, together with initial and boundary conditions. Some suitable non-dimensional variables are introduced. The Laplace transform method is used to obtain the exact solutions of the corresponding non-dimensional momentum and energy equations with conditions. Solutions of the velocity for cosine and sine oscillations as well as for temperature fields are obtained and displayed graphically for different values of time ( t ), the Grashof number ( Gr ), the Prandtl number ([Formula: see text]), and the phase angle ([Formula: see text]). Skin friction and the Nusselt number are also evaluated. The exact solutions are obtained and in limiting cases, the present solutions are found to be identical to the published results. Further, the obtained exact solutions also validated by comparing with results obtained by using Gaver-Stehfest algorithm. The interested physical property such as velocity, temperature, skin friction and Nusselt number are affected by the embedded parameters time ( t ), the Grashof number ( Gr ), the Prandtl number ([Formula: see text]), and the phase angle ([Formula: see text]).

Chemiluminescence development after initiation of Maillard reaction in aqueous solutions of glycine and glucose: nonlinearity of the process and cooperative properties of the reaction system

NASA Astrophysics Data System (ADS)

Voeikov, Vladimir L.; Naletov, Vladimir I.

1998-06-01

Nonenzymatic glycation of free or peptide bound amino acids (Maillard reaction, MR) plays an important role in aging, diabetic complications and atherosclerosis. MR taking place at high temperatures is accompanied by chemiluminescence (CL). Here kinetics of CL development in MR proceeding in model systems at room temperature has been analyzed for the first time. Brief heating of glycine and D-glucose solutions to t greater than 93 degrees Celsius results in their browning and appearance of fluorescencent properties. Developed In solutions rapidly cooled down to 20 degrees Celsius a wave of CL. It reached maximum intensity around 40 min after the reaction mixture heating and cooling it down. CL intensity elevation was accompanied by certain decoloration of the solution. Appearance of light absorbing substances and development of CL depended critically upon the temperature of preincubation (greater than or equal to 93 degrees Celsius), initial pH (greater than or equal to 11,2), sample volume (greater than or equal to 0.5 ml) and reagents concentrations. Dependence of total counts accumulation on a system volume over the critical volume was non-monotonous. After reaching maximum values CL began to decline, though only small part of glucose and glycin had been consumed. Brief heating of such solutions to the critical temperature resulted in emergence of a new CL wave. This procedure could be repeated in one and the same reaction system for several times. Whole CL kinetic curve best fitted to lognormal distribution. Macrokinetic properties of the process are characteristic of chain reactions with delayed branching. Results imply also, that self-organization occurs in this system, and that the course of the process strongly depends upon boundary conditions and periodic interference in its course.

Adsorption and Desorption of Nickel(II) Ions from Aqueous Solution by a Lignocellulose/Montmorillonite Nanocomposite

PubMed Central

Zhang, Xiaotao; Wang, Ximing

2015-01-01

A new and inexpensive lignocellulose/montmorillonite (LNC/MMT) nanocomposite was prepared by a chemical intercalation of LNC into MMT and was subsequently investigated as an adsorbent in batch systems for the adsorption-desorption of Ni(II) ions in an aqueous solution. The optimum conditions for the Ni(II) ion adsorption capacity of the LNC/MMT nanocomposite were studied in detail by varying parameters such as the initial Ni(II) concentration, the solution pH value, the adsorption temperature and time. The results indicated that the maximum adsorption capacity of Ni(II) reached 94.86 mg/g at an initial Ni(II) concentration of 0.0032 mol/L, a solution pH of 6.8, an adsorption temperature of 70°C, and adsorption time of 40 min. The represented adsorption kinetics model exhibited good agreement between the experimental data and the pseudo-second-order kinetic model. The Langmuir isotherm equation best fit the experimental data. The structure of the LNC/MMT nanocomposite was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), whereas the adsorption mechanism was discussed in combination with the results obtained from scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier-transform infrared spectroscopy analyses (FTIR). The desorption capacity of the LNC/MMT nanocomposite depended on parameters such as HNO3 concentration, desorption temperature, and desorption time. The satisfactory desorption capacity of 81.34 mg/g was obtained at a HNO3 concentration, desorption temperature, and desorption time of 0.2 mol/L, 60 ºC, and 30 min, respectively. The regeneration studies showed that the adsorption capacity of the LNC/MMT nanocomposite was consistent for five cycles without any appreciable loss in the batch process and confirmed that the LNC/MMT nanocomposite was reusable. The overall study revealed that the LNC/MMT nanocomposite functioned as an effective adsorbent in the detoxification of Ni(II)-contaminated wastewater. PMID:25647398

Fluidized bed gasification of extracted coal

DOEpatents

Aquino, Dolores C.; DaPrato, Philip L.; Gouker, Toby R.; Knoer, Peter

1986-01-01

Coal or similar carbonaceous solids are extracted by contacting the solids in an extraction zone (12) with an aqueous solution having a pH above 12.0 at a temperature between 65.degree. C. and 110.degree. C. for a period of time sufficient to remove bitumens from the coal into said aqueous solution and the extracted solids are then gasified at an elevated pressure and temperature in a fluidized bed gasification zone (60) wherein the density of the fluidized bed is maintained at a value above 160 kg/m.sup.3. In a preferred embodiment of the invention, water is removed from the aqueous solution in order to redeposit the extracted bitumens onto the solids prior to the gasification step.

Pressure in isochoric systems containing aqueous solutions at subzero Centigrade temperatures.

PubMed

Ukpai, Gideon; Năstase, Gabriel; Șerban, Alexandru; Rubinsky, Boris

2017-01-01

Preservation of biological materials at subzero Centigrade temperatures, cryopreservation, is important for the field of tissue engineering and organ transplantation. Our group is studying the use of isochoric (constant volume) systems of aqueous solution for cryopreservation. Previous studies measured the pressure-temperature relations in aqueous isochoric systems in the temperature range from 0°C to - 20°C. The goal of this study is to expand the pressure-temperature measurement beyond the range reported in previous publications. To expand the pressure-temperature measurements beyond the previous range, we have developed a new isochoric device capable of withstanding liquid nitrogen temperatures and pressures of up to 413 MPa. The device is instrumented with a pressure transducer than can monitor and record the pressures in the isochoric chamber in real time. Measurements were made in a temperature range from - 5°C to liquid nitrogen temperatures for various solutions of pure water and Me2SO (a chemical additive used for protection of biological materials in a frozen state and for vitrification (glass formation) of biological matter). Undissolved gaseous are is carefully removed from the system. Temperature-pressure data from - 5°C to liquid nitrogen temperature for pure water and other solutions are presented in this study. Following are examples of some, temperature-pressure values, that were measured in an isochoric system containing pure water: (- 20°C, 187 MPa); (-25°C, 216 MPa); (- 30°C, 242.3 MPa); (-180°C, 124 MPa). The data is consistent with the literature, which reports that the pressure and temperature at the triple point, between ice I, ice III and water is, - 21.993°C and 209.9 MPa, respectively. It was surprising to find that the pressure in the isochoric system increases at temperatures below the triple point and remains high to liquid nitrogen temperatures. Measurements of pressure-temperature relations in solutions of pure water and Me2SO in different concentrations show that, for concentrations in which vitrification is predicted, no increase in pressure was measured during rapid cooling to liquid nitrogen temperatures. However, ice formation either during cooling or warming to and from liquid nitrogen temperatures produced an increase in pressure. The data obtained in this study can be used to aid in the design of isochoric cryopreservation protocols. The results suggest that the pressure measurement is important in the design of "constant volume" systems and can provide a simple means to gain information on the occurrence of vitrification and devitrification during cryopreservation processes of aqueous solutions in an isochoric system.

Production of chitosan-based non-woven membranes using the electrospinning process

NASA Astrophysics Data System (ADS)

Pakravan Lonbani, Mehdi

Chitosan is a modified natural polymer mainly produced from chitin, one of the most abundant organic materials in the world. Highly porous chitosan mats present the specific physicochemical properties of the base material and also benefit from the physical characteristics of nanoporous membranes. Electrospinning is a novel technique developed long time ago and revisited recently that can generate polymeric fibers with nanometric size. The ultimate purpose of this work is to fabricate microporous non-woven chitosan membranes for wound healing dressings and heavy metal ion removal from drinking water. In this dissertation, two approaches have been utilized to prepare chitosan-based nanofibers; blending and co-axial electrospinning of chitosan solution with a readily electrospinnable solution, i.e. an aqueous solution of polyethylene oxide (PEO). Consequently, understanding the phase behavior and miscibility of aqueous acidic solutions of chitosan and PEO and their blends is of crucial importance, as any phase separation occurring during the electrospinning process greatly changes the morphology and physico-mechanical properties of the final products. First we employed the rheological approach on a well-known aqueous PEO solution to develop the experimental protocol. By comparing these critical points with that obtained from other experimental techniques, we showed that rheological measurements can sensitively detect early stages of phase separation. Subsequently the method was applied to 50 wt% aqueous acetic acid solutions of PEO, chitosan and their blends at different ratios. These solutions showed a lower critical solution temperature (LCST) phase diagram that is attributed to the existence of hydrogen bonds between active groups on chitosan and PEO backbone and the solvent. Critical decomposition temperatures for binodal and spinodal points were estimated from isochronal temperature sweep experiments. The obtained binodal temperatures confirmed that chitosan/PEO solutions are miscible and stable at moderate temperatures and phase separate at higher temperatures of 60-75 °C. Then, we intended to obtain a thorough understanding of chitosan/PEO solution properties that lead to a successful electrospinning process, i.e. continuous and stable, and which produces defect free uniform beadless nanofibers. The effect of blend composition and acetic acid concentration on properties such as surface tension and conductivity and, ultimately, on electrospinnability were investigated. A highly deacetylated chitosan (DDA=97.5 %) in 50% acetic acid was used, which is the maximum deacetylated chitosan grade that has been reported for the preparation of electrospun chitosan-based nanofibers. The rheological characteristics of the chitosan/PEO solutions as a controlling parameter in the electrospinning process were examined and their relationships to electrospinnability presented. As we showed that chitosan/PEO solutions are miscible and stable at moderate temperatures, a modified electrospinning set up to electrospin at temperatures of 25-70 °C was designed to achieve content as high as 90 wt% of chitosan in beadless chitosan/PEO nanofibers of 60-80 nm in diameter. It was also found that increasing chitosan/PEO ratio from 50/50 to 90/10 led to a remarkable diameter reduction from 123 to 63 nm at room temperature. Additionally, we found that moderate process temperatures help to stabilize the electrospinning process of these solutions and produce beadless nanofibers. However, at higher temperatures, the electrospun jet became unstable and beaded fiber morphology was obtained. This phenomena occurs closely at the temperature range of phase separation, previously determined by rheology studies. Therefore, temperature-induced phase separation of these solutions is considered as the reason for that observation. On the other hand, an FTIR study at room temperature on cast films and nanofibers of chitosan/PEO blends at room temperature showed the presence of hydrogen bonding interactions between chitosan and PEO that could be an another indication of miscibility between these two polymers in solution at moderate temperatures. Finally, in order to remove the blending step, reducing the amount of chitosan used and also to put chitosan right on the outer surface of the nanofibers for further related applications, a co-axial electrospinning technique was employed. By using a one-step co-axial electrospinning process, for the first time core-shell structured PEO-chitosan nanofibers from aqueous solutions were produced in which chitosan is located at the shell (outer layer) and PEO at the core (inner layer). Uniform sized defect-free nanofibers of 100-190 nm diameter were produced. The core-shell nanostructure and existence of chitosan on the shell layer were confirmed by TEM images obtained before and after washing the PEO content with water. The presence of chitosan on the surface of the composite nanofibers was further supported by XPS studies. Bulk and local compositional analysis is performed by thermal gravimetry (TGA) and Fourier transform infrared spectroscopy (FTIR) techniques, respectively, to examine the homogeneity of the nanofibers. Additionally, it was shown that hollow chitosan nanofibers could be obtained by PEO washing of the co-axial PEO/chitosan nanofibers, which could also be of great interest in applications such as blood purification in hemodialysis.

Stability of acetylcysteine solution repackaged in oral syringes and associated cost savings.

PubMed

Kiser, Tyree H; Oldland, Alan R; Fish, Douglas N

2007-04-01

The physical and chemical stability of repackaged acetylcysteine 600 mg/3 mL solution in oral syringes stored under refrigeration or at room temperature was studied for six months; a cost analysis was also conducted. Acetylcysteine 20% solution for inhalation was repackaged undiluted as 600 mg/3 mL in capped oral syringes and stored either under refrigeration or at room temperature exposed to fluorescent light. Four samples for each storage condition were analyzed in duplicate on day zero, weekly for the first month, and then every two weeks during months 2-6. Physical stability was assessed, and the chemical stability of acetylcysteine was evaluated by high-performance liquid chromatography. Acetylcysteine solution in syringes was physically stable during the entire six-month study period. When stored at room temperature, acetylcysteine retained 99% of the original concentration at three months and 95% at six months after preparation of the syringes. Loss of acetylcysteine was <2% at six months when stored under refrigeration. Packaging acetylcysteine in batches of 100 syringes instead of preparing individual syringes reduced wastage to zero syringes, saving an estimated $247 in drug costs. The estimated pharmacy time savings was 30 hours ($702). Acetylcysteine 20% solution repackaged as 600 mg/3 mL in oral syringes is both physically and chemically stable under refrigeration or at room temperature under normal fluorescent lighting for six months. The total loss of acetylcysteine was approximately 5% at room temperature under fluorescent lighting and <2% under refrigeration. Repackaging the solution in syringes in bulk rather than in single doses demonstrated a measurable cost saving.

A scientific report on heat transfer analysis in mixed convection flow of Maxwell fluid over an oscillating vertical plate.

PubMed

Khan, Ilyas; Shah, Nehad Ali; Dennis, L C C

2017-03-15

This scientific report investigates the heat transfer analysis in mixed convection flow of Maxwell fluid over an oscillating vertical plate with constant wall temperature. The problem is modelled in terms of coupled partial differential equations with initial and boundary conditions. Some suitable non-dimensional variables are introduced in order to transform the governing problem into dimensionless form. The resulting problem is solved via Laplace transform method and exact solutions for velocity, shear stress and temperature are obtained. These solutions are greatly influenced with the variation of embedded parameters which include the Prandtl number and Grashof number for various times. In the absence of free convection, the corresponding solutions representing the mechanical part of velocity reduced to the well known solutions in the literature. The total velocity is presented as a sum of both cosine and sine velocities. The unsteady velocity in each case is arranged in the form of transient and post transient parts. It is found that the post transient parts are independent of time. The solutions corresponding to Newtonian fluids are recovered as a special case and comparison between Newtonian fluid and Maxwell fluid is shown graphically.

A scientific report on heat transfer analysis in mixed convection flow of Maxwell fluid over an oscillating vertical plate

NASA Astrophysics Data System (ADS)

Khan, Ilyas; Shah, Nehad Ali; Dennis, L. C. C.

2017-03-01

This scientific report investigates the heat transfer analysis in mixed convection flow of Maxwell fluid over an oscillating vertical plate with constant wall temperature. The problem is modelled in terms of coupled partial differential equations with initial and boundary conditions. Some suitable non-dimensional variables are introduced in order to transform the governing problem into dimensionless form. The resulting problem is solved via Laplace transform method and exact solutions for velocity, shear stress and temperature are obtained. These solutions are greatly influenced with the variation of embedded parameters which include the Prandtl number and Grashof number for various times. In the absence of free convection, the corresponding solutions representing the mechanical part of velocity reduced to the well known solutions in the literature. The total velocity is presented as a sum of both cosine and sine velocities. The unsteady velocity in each case is arranged in the form of transient and post transient parts. It is found that the post transient parts are independent of time. The solutions corresponding to Newtonian fluids are recovered as a special case and comparison between Newtonian fluid and Maxwell fluid is shown graphically.

A scientific report on heat transfer analysis in mixed convection flow of Maxwell fluid over an oscillating vertical plate

PubMed Central

Khan, Ilyas; Shah, Nehad Ali; Dennis, L. C. C.

2017-01-01

This scientific report investigates the heat transfer analysis in mixed convection flow of Maxwell fluid over an oscillating vertical plate with constant wall temperature. The problem is modelled in terms of coupled partial differential equations with initial and boundary conditions. Some suitable non-dimensional variables are introduced in order to transform the governing problem into dimensionless form. The resulting problem is solved via Laplace transform method and exact solutions for velocity, shear stress and temperature are obtained. These solutions are greatly influenced with the variation of embedded parameters which include the Prandtl number and Grashof number for various times. In the absence of free convection, the corresponding solutions representing the mechanical part of velocity reduced to the well known solutions in the literature. The total velocity is presented as a sum of both cosine and sine velocities. The unsteady velocity in each case is arranged in the form of transient and post transient parts. It is found that the post transient parts are independent of time. The solutions corresponding to Newtonian fluids are recovered as a special case and comparison between Newtonian fluid and Maxwell fluid is shown graphically. PMID:28294186

Embedded infrared fiber-optic sensor for thermometry in a high temperature/pressure environment

NASA Astrophysics Data System (ADS)

Yoo, Wook Jae; Jang, Kyoung Won; Moon, Jinsoo; Han, Ki-Tek; Jeon, Dayeong; Lee, Bongsoo; Park, Byung Gi

2012-11-01

In this study, we developed an embedded infrared fiber-optic temperature sensor for thermometry in high temperature/pressure and water-chemistry environments by using two identical silver-halide optical fibers. The performance of the fabricated temperature sensor was assessed in an autoclave filled with an aqueous coolant solution containing boric acid and lithium hydroxide. We carried out real-time monitoring of the infrared radiation emitted from the signal and reference probes for various temperatures over a temperature range from 95 to 225 °C. In order to decide the temperature of the synthetic coolant solution, we measured the difference between the infrared radiation emitted from the two temperature-sensing probes. Thermometry with the proposed sensor is immune to any changes in the physical conditions and the emissivity of the heat source. From the experimental results, the embedded infrared fiber-optic temperature sensor can withstand, and normally operate in a high temperature/pressure test loop system corresponding to the coolant system used for nuclear power plant simulation. We expect that the proposed sensor can be developed to accurately monitor temperatures in harsh environments.

Process effects on activated carbon with large specific surface area from corn cob.

PubMed

Cao, Qing; Xie, Ke-Chang; Lv, Yong-Kang; Bao, Wei-Ren

2006-01-01

The main factors that affect the large specific surface area (SSA) of the activated carbon from agricultural waste corn cobs were studied by chemically activated method with solution of KOH and soap which acted as surfactant. The experiment showed that not only the activation temperature, activation time and the mass ratio of KOH to the carbonized material, but also the activated methods using activator obviously influenced the SSA of activated carbon. The experimental operating conditions were as follows: the carbonized temperature being 450 degrees C and keeping time being 4 h using N2 as protective gas; the activation temperature being 850 degrees C and holding time being 1.2 h; the mass ratio of KOH to carbonized material being 4.0; the time of soaking carbonized material in the solution of KOH and soap being 30 min. Under the optimal conditions, the SSA of activated carbon from corn cobs reached 2700 m2/g. And the addition of the soap as surfactant may shorten the soaking time. The structure of the activated carbon prepared had narrow distribution of pore size and the micro-pores accounted for 78%. The advantages of the method described were easy and feasible.

Separation and Precipitation of Nickel from Acidic Sulfate Leaching Solution of Molybdenum-Nickel Black Shale by Potassium Nickel Sulfate Hexahydrate Crystallization

NASA Astrophysics Data System (ADS)

Deng, Zhigan; Wei, Chang; Fan, Gang; Li, Xingbin; Li, Minting; Li, Cunxiong

2018-02-01

Nickel was separated and precipitated with potassium nickel sulfate hexahydrate [K2Ni(SO4)2·6H2O] from acidic sulfate solution, a leach solution from molybdenum-nickel black shale. The effects of the potassium sulfate (K2SO4) concentration, crystallization temperature, solution pH, and crystallization time on nickel(II) recovery and iron(III) precipitation were investigated, revealing that nickel and iron were separated effectively. The optimum parameters were K2SO4 concentration of 200 g/L, crystallization temperature of 10°C, solution pH of 0.5, and crystallization time of 24 h. Under these conditions, 97.6% nickel(II) was recovered as K2Ni(SO4)2·6H2O crystals while only 2.0% of the total iron(III) was precipitated. After recrystallization, 98.4% pure K2Ni(SO4)2·6H2O crystals were obtained in the solids. The mother liquor was purified by hydrolysis-precipitation followed by cooling, and more than 99.0% K2SO4 could be crystallized. A process flowsheet was developed to separate iron(III) and nickel(II) from acidic-sulfate solution.

Predicting adsorptive removal of chlorophenol from aqueous solution using artificial intelligence based modeling approaches.

PubMed

Singh, Kunwar P; Gupta, Shikha; Ojha, Priyanka; Rai, Premanjali

2013-04-01

The research aims to develop artificial intelligence (AI)-based model to predict the adsorptive removal of 2-chlorophenol (CP) in aqueous solution by coconut shell carbon (CSC) using four operational variables (pH of solution, adsorbate concentration, temperature, and contact time), and to investigate their effects on the adsorption process. Accordingly, based on a factorial design, 640 batch experiments were conducted. Nonlinearities in experimental data were checked using Brock-Dechert-Scheimkman (BDS) statistics. Five nonlinear models were constructed to predict the adsorptive removal of CP in aqueous solution by CSC using four variables as input. Performances of the constructed models were evaluated and compared using statistical criteria. BDS statistics revealed strong nonlinearity in experimental data. Performance of all the models constructed here was satisfactory. Radial basis function network (RBFN) and multilayer perceptron network (MLPN) models performed better than generalized regression neural network, support vector machines, and gene expression programming models. Sensitivity analysis revealed that the contact time had highest effect on adsorption followed by the solution pH, temperature, and CP concentration. The study concluded that all the models constructed here were capable of capturing the nonlinearity in data. A better generalization and predictive performance of RBFN and MLPN models suggested that these can be used to predict the adsorption of CP in aqueous solution using CSC.

Adsorption of cesium on cement mortar from aqueous solutions.

PubMed

Volchek, Konstantin; Miah, Muhammed Yusuf; Kuang, Wenxing; DeMaleki, Zack; Tezel, F Handan

2011-10-30

The adsorption of cesium on cement mortar from aqueous solutions was studied in series of bench-scale tests. The effects of cesium concentration, temperature and contact time on process kinetics and equilibrium were evaluated. Experiments were carried out in a range of initial cesium concentrations from 0.0103 to 10.88 mg L(-1) and temperatures from 278 to 313 K using coupons of cement mortar immersed in the solutions. Non-radioactive cesium chloride was used as a surrogate of the radioactive (137)Cs. Solution samples were taken after set periods of time and analyzed by inductively coupled plasma mass spectroscopy. Depending on the initial cesium concentration, its equilibrium concentration in solution ranged from 0.0069 to 8.837 mg L(-1) while the respective surface concentration on coupons varied from 0.0395 to 22.34 μg cm(-2). Equilibrium test results correlated well with the Freundlich isotherm model for the entire test duration. Test results revealed that an increase in temperature resulted in an increase in adsorption rate and a decrease in equilibrium cesium surface concentration. Among several kinetic models considered, the pseudo-second order reaction model was found to be the best to describe the kinetic test results in the studied range of concentrations. The adsorption activation energy determined from Arrhenius equation was found to be approximately 55.9 kJ mol(-1) suggesting that chemisorption was the prevalent mechanism of interaction between cesium ions and cement mortar. Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.

ANN based Real-Time Estimation of Power Generation of Different PV Module Types

NASA Astrophysics Data System (ADS)

Syafaruddin; Karatepe, Engin; Hiyama, Takashi

Distributed generation is expected to become more important in the future generation system. Utilities need to find solutions that help manage resources more efficiently. Effective smart grid solutions have been experienced by using real-time data to help refine and pinpoint inefficiencies for maintaining secure and reliable operating conditions. This paper proposes the application of Artificial Neural Network (ANN) for the real-time estimation of the maximum power generation of PV modules of different technologies. An intelligent technique is necessary required in this case due to the relationship between the maximum power of PV modules and the open circuit voltage and temperature is nonlinear and can't be easily expressed by an analytical expression for each technology. The proposed ANN method is using input signals of open circuit voltage and cell temperature instead of irradiance and ambient temperature to determine the estimated maximum power generation of PV modules. It is important for the utility to have the capability to perform this estimation for optimal operating points and diagnostic purposes that may be an early indicator of a need for maintenance and optimal energy management. The proposed method is accurately verified through a developed real-time simulator on the daily basis of irradiance and cell temperature changes.

Physico-chemical stability of busulfan in injectable solutions in various administration packages.

PubMed

Houot, Mélanie; Poinsignon, Vianney; Mercier, Lionel; Valade, Cyril; Desmaris, Romain; Lemare, François; Paci, Angelo

2013-03-01

Busulfan is used as part of a conditioning regimen prior to hematopoietic stem cell transplantation for the treatment of certain cancers and immune deficiency syndromes. Due to its instability in aqueous preparations, busulfan for infusion is prepared from a concentrate and has a relatively short shelf life once prepared. The purpose of this study was to identify the most suitable storage container and temperature to maximize the shelf life of busulfan therapeutic infusions prepared from Busilvex(®). Busilvex(®) 6 mg/mL was diluted to 0.55 mg/mL with 0.9 % NaCl and aliquots dispensed into polypropylene syringes, polyvinyl chloride bags, and glass bottles. Three storage temperatures were evaluated: 2-8 °C, 13-15 °C (thermostatically controlled chamber), and room temperature (20 ± 5 °C). At set time points, samples were analysed for busulfan content, using a high-performance liquid chromatography (HPLC) system with ultraviolet detection. The change in pH and osmolarity on storage was also determined, and solutions were inspected visually for formation of a precipitate or colour change. To determine the contribution of precipitation to loss of busulfan content on storage, samples from one time series were treated with the solvent dimethylacetamide prior to HPLC separation and quantitation of busulfan. The results of the active substance content monitoring study over a 48-h period demonstrate that busulfan solution is stable at a 5 % threshold, at 2-8 °C for 16 h in syringes, 14 h in glass bottles, and 6 h in bags. In addition, the period of stability decreases as the temperature increases (4 h at 20 ± 5 °C). The solution is considered to be stable, subject to precipitation liable to be observed regardless of the temperature. The best stability was observed for busulfan solutions placed at 2-8 °C in syringes. This study demonstrated that precipitation, in addition to hydrolysis, has a significant influence on the busulfan content.

High-temperature low-cycle-fatigue and crack-growth behaviors of three superalloys: HASTELLOY X, HAYNES 230, and HAYNES 188

NASA Astrophysics Data System (ADS)

Lu, Yulin

Low cycle fatigue (LCF) and fatigue crack growth (FCG) experiments on three superalloys HASTELLOY X, HAYNES 230, and HAYNES 188 have been conducted at temperatures from 649 to 982°C. Hold times were imposed at the maximum strain or load to investigate the hold-time effect. In general, the fatigue life decreased as the temperature or hold time increased. However, for the HAYNES 230 alloy at total strain ranges higher than 1.0% and without a hold time, the LCF life was longer at 927°C than at 816°C. This "abnormal" behavior was found to result from the smaller plastic strain amplitude at half-life at 927°C than that at 816°C. An increase in the temperature and/or the introduction of a hold time decreased the hardening rate and increased the softening rate for all the three alloys. The introduction of a hold time and/or the increase of the test temperature progressively changed the fracture mode from the transgranular to mixed trans/inter-granular, then to intergranular feature. Within the two phases of the fatigue process, crack initiation was more severely influenced by the change of the hold time and/or temperature. The FCG data of HASTELLOY X and HAYNES 230 alloys were analyzed with an emphasis on hold-time and temperature effects. The crack grew faster at a higher temperature and a longer hold time. Fracture-mechanics parameters, C*, Ct, and (Ct)avg, were applied to correlate the crack-growth rates. The fatigue-cracking path was mainly transgranular at 816 and 927°C. The cracking path became dominantly intergranular if the hold time increased to 2 min, indicating that the time-dependent damage mechanisms were in control. The Ct and (Ct)avg parameters were capable of consolidating time dependent crack growth rate from different temperatures and alloys. The tests were conducted in air. Therefore, the fracture surfaces were frequently covered with a dark layer of oxides, making fracture feature difficult to identify under scanning-electron-microscopy. To overcome this problem, an oxide-stripping technique has been developed. The sample is first boiled in a potassium permanganate solution for 1 h, and then electrolytically cleaned in an alkaline solution for 5 min.

Cooling and Warming Laws: An Exact Analytical Solution

ERIC Educational Resources Information Center

Besson, Ugo

2010-01-01

This paper deals with temperature variations over time of objects placed in a constant-temperature environment in the presence of thermal radiation. After a historical introduction, the paper discusses cooling and warming laws, by taking into account first solely object-environment energy exchange by thermal radiation, and then adding…

XpertTrack: Precision Autonomous Measuring Device Developed for Real Time Shipments Tracker

PubMed Central

Viman, Liviu; Daraban, Mihai; Fizesan, Raul; Iuonas, Mircea

2016-01-01

This paper proposes a software and hardware solution for real time condition monitoring applications. The proposed device, called XpertTrack, exchanges data through the GPRS protocol over a GSM network and monitories temperature and vibrations of critical merchandise during commercial shipments anywhere on the globe. Another feature of this real time tracker is to provide GPS and GSM positioning with a precision of 10 m or less. In order to interpret the condition of the merchandise, the data acquisition, analysis and visualization are done with 0.1 °C accuracy for the temperature sensor, and 10 levels of shock sensitivity for the acceleration sensor. In addition to this, the architecture allows increasing the number and the types of sensors, so that companies can use this flexible solution to monitor a large percentage of their fleet. PMID:26978360

XpertTrack: Precision Autonomous Measuring Device Developed for Real Time Shipments Tracker.

PubMed

Viman, Liviu; Daraban, Mihai; Fizesan, Raul; Iuonas, Mircea

2016-03-10

This paper proposes a software and hardware solution for real time condition monitoring applications. The proposed device, called XpertTrack, exchanges data through the GPRS protocol over a GSM network and monitories temperature and vibrations of critical merchandise during commercial shipments anywhere on the globe. Another feature of this real time tracker is to provide GPS and GSM positioning with a precision of 10 m or less. In order to interpret the condition of the merchandise, the data acquisition, analysis and visualization are done with 0.1 °C accuracy for the temperature sensor, and 10 levels of shock sensitivity for the acceleration sensor. In addition to this, the architecture allows increasing the number and the types of sensors, so that companies can use this flexible solution to monitor a large percentage of their fleet.

Solute segregation kinetics and dislocation depinning in a binary alloy

NASA Astrophysics Data System (ADS)

Dontsova, E.; Rottler, J.; Sinclair, C. W.

2015-06-01

Static strain aging, a phenomenon caused by diffusion of solute atoms to dislocations, is an important contributor to the strength of substitutional alloys. Accurate modeling of this complex process requires both atomic spatial resolution and diffusional time scales, which is very challenging to achieve with commonly used atomistic computational methods. In this paper, we use the recently developed "diffusive molecular dynamics" (DMD) method that is capable of describing the kinetics of the solute segregation process at the atomic level while operating on diffusive time scales in a computationally efficient way. We study static strain aging in the Al-Mg system and calculate the depinning shear stress between edge and screw dislocations and their solute atmospheres formed for various waiting times with different solute content and for a range of temperatures. A simple phenomenological model is also proposed that describes the observed behavior of the critical shear stress as a function of segregation level.

Implementation of one and three dimensional models for heat transfer coeffcient identification over the plate cooled by the circular water jets

NASA Astrophysics Data System (ADS)

Malinowski, Zbigniew; Cebo-Rudnicka, Agnieszka; Hadała, Beata; Szajding, Artur; Telejko, Tadeusz

2017-10-01

A cooling rate affects the mechanical properties of steel which strongly depend on microstructure evolution processes. The heat transfer boundary condition for the numerical simulation of steel cooling by water jets can be determined from the local one dimensional or from the three dimensional inverse solutions in space and time. In the present study the inconel plate has been heated to about 900 °C and then cooled by six circular water jets. The plate temperature has been measured by 30 thermocouples. The heat transfer coefficient and the heat flux distributions at the plate surface have been determined in time and space. The one dimensional solutions have given a local error to the heat transfer coefficient of about 35%. The three dimensional inverse solution has allowed reducing the local error to about 20%. The uncertainty test has confirmed that a better approximation of the heat transfer coefficient distribution over the cooled surface can be obtained even for limited number of thermocouples. In such a case it was necessary to constrain the inverse solution with the interpolated temperature sensors.

Silicon nitride-aluminum oxide solid solution (SiAION) formation and densification by pressure sintering

NASA Technical Reports Server (NTRS)

Yeh, H. C.; Sanders, W. A.; Fiyalko, J. L.

1975-01-01

Stirred-ball-mill-blended Si3N4 and Al2O3 powders were pressure sintered in order to investigate the mechanism of solid solution formation and densification in the Si3N4-Al2O3 system. Powder blends with Si3N4:Al2O3 mole ratios of 4:1, 3:2, and 2:3 were pressure sintered at 27.6-MN/sq m pressure at temperatures to 17000 C (3090 F). The compaction behavior of the powder blends during pressure sintering was determined by observing the density of the powder compact as a function of temperature and time starting from room temperature. This information, combined with the results of X-ray diffraction and metallographic analyses regarding solutioning and phase transformation phenomena in the Si3N4-Al2O3 system, was used to describe the densification behavior.

Hydration and dielectrical properties of aqueous pyrrolidinium trifluoroacetate solutions

NASA Astrophysics Data System (ADS)

Lyashchenko, A. K.; Balakaeva, I. V.; Simonova, Yu. A.; Timofeeva, L. M.

2017-10-01

Results from microwave measurements of the dielectrical properties of aqueous pyrrolidinium trifluoroacetate solutions at maximum water dispersion frequencies (13-25 GHz) and temperatures of 288, 298, and 308 K are given. The static dielectrical constants, times, and activation parameters of the dielectrical relaxation of solutions are calculated. The enthalpy and time of dielectrical relaxation activation are increased by deceleration of the motion of water molecules in the hydrate shells of ions. The changes in dielectrical parameters are in this case minimal in a series of aqueous solutions of diallylammonium salts with cations of different structures and degrees of substitution. It is shown that pyrrolidinium ions are characterized by weak hydrophobic hydration.

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

Jinlong, Lv, E-mail: ljlbuaa@126.com; State Key Lab of New Ceramic and Fine Processing, Tsinghua University, Beijing 100084; Tongxiang, Liang, E-mail: ljltsinghua@126.com

The nanocrystalline pure nickels with different grain orientations were fabricated by direct current electrodeposition process. The grain size slightly decreased with the increasing of electrodeposition solution temperature. However, grain orientation was affected significantly. Comparing with samples obtained at 50 °C and 80 °C, sample obtained at 20 °C had the strongest (111) orientation plane which increased electrochemical corrosion resistance of this sample. At the same time, the lowest (111) orientation plane deteriorated electrochemical corrosion resistance of sample obtained at 50 °C. - Graphical abstract: The increased electrodeposition temperature promoted slightly grain refinement. The grain orientation was affected significantly by electrodepositionmore » solution temperature. The (111) orientation plane of sample increased significantly corrosion resistance. Display Omitted.« less

The iterative thermal emission method: A more implicit modification of IMC

NASA Astrophysics Data System (ADS)

Long, A. R.; Gentile, N. A.; Palmer, T. S.

2014-11-01

For over 40 years, the Implicit Monte Carlo (IMC) method has been used to solve challenging problems in thermal radiative transfer. These problems typically contain regions that are optically thick and diffusive, as a consequence of the high degree of ;pseudo-scattering; introduced to model the absorption and reemission of photons from a tightly-coupled, radiating material. IMC has several well-known features that could be improved: a) it can be prohibitively computationally expensive, b) it introduces statistical noise into the material and radiation temperatures, which may be problematic in multiphysics simulations, and c) under certain conditions, solutions can be nonphysical, in that they violate a maximum principle, where IMC-calculated temperatures can be greater than the maximum temperature used to drive the problem. We have developed a variant of IMC called iterative thermal emission IMC, which is designed to have a reduced parameter space in which the maximum principle is violated. ITE IMC is a more implicit version of IMC in that it uses the information obtained from a series of IMC photon histories to improve the estimate for the end of time step material temperature during a time step. A better estimate of the end of time step material temperature allows for a more implicit estimate of other temperature-dependent quantities: opacity, heat capacity, Fleck factor (probability that a photon absorbed during a time step is not reemitted) and the Planckian emission source. We have verified the ITE IMC method against 0-D and 1-D analytic solutions and problems from the literature. These results are compared with traditional IMC. We perform an infinite medium stability analysis of ITE IMC and show that it is slightly more numerically stable than traditional IMC. We find that significantly larger time steps can be used with ITE IMC without violating the maximum principle, especially in problems with non-linear material properties. The ITE IMC method does however yield solutions with larger variance because each sub-step uses a different Fleck factor (even at equilibrium).

The iterative thermal emission method: A more implicit modification of IMC

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

Long, A.R., E-mail: arlong.ne@tamu.edu; Gentile, N.A.; Palmer, T.S.

2014-11-15

For over 40 years, the Implicit Monte Carlo (IMC) method has been used to solve challenging problems in thermal radiative transfer. These problems typically contain regions that are optically thick and diffusive, as a consequence of the high degree of “pseudo-scattering” introduced to model the absorption and reemission of photons from a tightly-coupled, radiating material. IMC has several well-known features that could be improved: a) it can be prohibitively computationally expensive, b) it introduces statistical noise into the material and radiation temperatures, which may be problematic in multiphysics simulations, and c) under certain conditions, solutions can be nonphysical, in thatmore » they violate a maximum principle, where IMC-calculated temperatures can be greater than the maximum temperature used to drive the problem. We have developed a variant of IMC called iterative thermal emission IMC, which is designed to have a reduced parameter space in which the maximum principle is violated. ITE IMC is a more implicit version of IMC in that it uses the information obtained from a series of IMC photon histories to improve the estimate for the end of time step material temperature during a time step. A better estimate of the end of time step material temperature allows for a more implicit estimate of other temperature-dependent quantities: opacity, heat capacity, Fleck factor (probability that a photon absorbed during a time step is not reemitted) and the Planckian emission source. We have verified the ITE IMC method against 0-D and 1-D analytic solutions and problems from the literature. These results are compared with traditional IMC. We perform an infinite medium stability analysis of ITE IMC and show that it is slightly more numerically stable than traditional IMC. We find that significantly larger time steps can be used with ITE IMC without violating the maximum principle, especially in problems with non-linear material properties. The ITE IMC method does however yield solutions with larger variance because each sub-step uses a different Fleck factor (even at equilibrium)« less

Thermal fluctuations of haemoglobin from different species: adaptation to temperature via conformational dynamics

PubMed Central

Stadler, A. M.; Garvey, C. J.; Bocahut, A.; Sacquin-Mora, S.; Digel, I.; Schneider, G. J.; Natali, F.; Artmann, G. M.; Zaccai, G.

2012-01-01

Thermodynamic stability, configurational motions and internal forces of haemoglobin (Hb) of three endotherms (platypus, Ornithorhynchus anatinus; domestic chicken, Gallus gallus domesticus and human, Homo sapiens) and an ectotherm (salt water crocodile, Crocodylus porosus) were investigated using circular dichroism, incoherent elastic neutron scattering and coarse-grained Brownian dynamics simulations. The experimental results from Hb solutions revealed a direct correlation between protein resilience, melting temperature and average body temperature of the different species on the 0.1 ns time scale. Molecular forces appeared to be adapted to permit conformational fluctuations with a root mean square displacement close to 1.2 Å at the corresponding average body temperature of the endotherms. Strong forces within crocodile Hb maintain the amplitudes of motion within a narrow limit over the entire temperature range in which the animal lives. In fully hydrated powder samples of human and chicken, Hb mean square displacements and effective force constants on the 1 ns time scale showed no differences over the whole temperature range from 10 to 300 K, in contrast to the solution case. A complementary result of the study, therefore, is that one hydration layer is not sufficient to activate all conformational fluctuations of Hb in the pico- to nanosecond time scale which might be relevant for biological function. Coarse-grained Brownian dynamics simulations permitted to explore residue-specific effects. They indicated that temperature sensing of human and chicken Hb occurs mainly at residues lining internal cavities in the β-subunits. PMID:22696485

Thermal fluctuations of haemoglobin from different species: adaptation to temperature via conformational dynamics.

PubMed

Stadler, A M; Garvey, C J; Bocahut, A; Sacquin-Mora, S; Digel, I; Schneider, G J; Natali, F; Artmann, G M; Zaccai, G

2012-11-07

Thermodynamic stability, configurational motions and internal forces of haemoglobin (Hb) of three endotherms (platypus, Ornithorhynchus anatinus; domestic chicken, Gallus gallus domesticus and human, Homo sapiens) and an ectotherm (salt water crocodile, Crocodylus porosus) were investigated using circular dichroism, incoherent elastic neutron scattering and coarse-grained Brownian dynamics simulations. The experimental results from Hb solutions revealed a direct correlation between protein resilience, melting temperature and average body temperature of the different species on the 0.1 ns time scale. Molecular forces appeared to be adapted to permit conformational fluctuations with a root mean square displacement close to 1.2 Å at the corresponding average body temperature of the endotherms. Strong forces within crocodile Hb maintain the amplitudes of motion within a narrow limit over the entire temperature range in which the animal lives. In fully hydrated powder samples of human and chicken, Hb mean square displacements and effective force constants on the 1 ns time scale showed no differences over the whole temperature range from 10 to 300 K, in contrast to the solution case. A complementary result of the study, therefore, is that one hydration layer is not sufficient to activate all conformational fluctuations of Hb in the pico- to nanosecond time scale which might be relevant for biological function. Coarse-grained Brownian dynamics simulations permitted to explore residue-specific effects. They indicated that temperature sensing of human and chicken Hb occurs mainly at residues lining internal cavities in the β-subunits.

Stability of urea in solution and pharmaceutical preparations.

PubMed

Panyachariwat, Nattakan; Steckel, Hartwig

2014-01-01

The stability of urea in solution and pharmaceutical preparations was analyzed as a function of temperature (25°-60°C), pH (3.11-9.67), and initial urea concentration (2.5%-20%). This study was undertaken to (i) obtain more extensive, quantitative information relative to the degradation of urea in both aqueous and non-aqueous solutions and in pharmaceutical preparations, and (ii) test the effects of initial urea concentration, pH, buffer, and temperature values on urea degradation. The stability analysis shows that urea is more stable at the pH range of 4-8 and the stability of urea decreases by increase in temperature for all pH values. Within the experimental range of temperature and initial urea concentration values, the lowest urea degradation was found with lactate buffer pH 6.0. The urea decomposition rate in solution and pharmaceutical preparations shows the dependence of the initial urea concentrations. At higher initial urea concentrations, the rate of degradation is a decreasing function with time. This suggests that the reverse reaction is a factor in the degradation of concentrated urea solution. For non-aqueous solvents, isopropanol showed the best effort in retarding the decomposition of urea. Since the losses in urea is directly influenced by its stability at a given temperature and pH, the stability analysis of urea by the proposed model can be used to prevent the loss and optimize the operating condition for urea-containing pharmaceutical preparations.

A new variable temperature solution-solid interface scanning tunneling microscope.

PubMed

Jahanbekam, Abdolreza; Mazur, Ursula; Hipps, K W

2014-10-01

We present a new solution-solid (SS) interface scanning tunneling microscope design that enables imaging at high temperatures with low thermal drift and with volatile solvents. In this new design, distinct from the conventional designs, the entire microscope is surrounded in a controlled-temperature and controlled-atmosphere chamber. This allows users to take measurements at high temperatures while minimizing thermal drift. By incorporating an open solution reservoir in the chamber, solvent evaporation from the sample is minimized; allowing users to use volatile solvents for temperature dependent studies at high temperatures. The new design enables the user to image at the SS interface with some volatile solvents for long periods of time (>24 h). An increase in the nonlinearity of the piezoelectric scanner in the lateral direction as a function of temperature is addressed. A temperature dependent study of cobalt(II) octaethylporphyrin (CoOEP) at the toluene/Au(111) interface has been performed with this instrument. It is demonstrated that the lattice parameters remain constant within experimental error from 24 °C to 75 °C. Similar quality images were obtained over the entire temperature range. We report the unit cell of CoOEP at the toluene/Au(111) interface (based on two molecules per unit cell) to be A = (1.36 ± 0.04) nm, B = (2.51 ± 0.04) nm, and α = 97° ± 2°.

A single-sweep, nanosecond time resolution laser temperature-jump apparatus

NASA Astrophysics Data System (ADS)

Ballew, R. M.; Sabelko, J.; Reiner, C.; Gruebele, M.

1996-10-01

We describe a fast temperature-jump (T-jump) apparatus capable of acquiring kinetic relaxation transients via real-time fluorescence detection over a time interval from nanoseconds to milliseconds in a single sweep. The method is suitable for aqueous solutions, relying upon the direct absorption of laser light by the bulk water. This obviates the need for additives (serving as optical or conductive heaters) that may interact with the sample under investigation. The longitudinal temperature profile is made uniform by counterpropagating heating pulses. Dead time is limited to one period of the probe laser (16 ns). The apparatus response is tested with aqueous tryptophan and the diffusion-controlled dimerization of proflavine.

Subcritical water extraction of amino acids from Mars analog soils.

PubMed

Noell, Aaron C; Fisher, Anita M; Fors-Francis, Kisa; Sherrit, Stewart

2018-01-18

For decades, the Martian regolith has stymied robotic mission efforts to catalog the organic molecules present. Perchlorate salts, found widely throughout Mars, are the main culprit as they breakdown and react with organics liberated from the regolith during pyrolysis, the primary extraction technique attempted to date on Mars. This work further develops subcritical water extraction (SCWE) as a technique for extraction of amino acids on future missions. The effect of SCWE temperature (185, 200, and 215°C) and duration of extraction (10-120 min) on the total amount and distribution of amino acids recovered was explored for three Mars analog soils (JSC Mars-1A simulant, an Atacama desert soil, and an Antarctic Dry Valleys soil) and bovine serum albumin (as a control solution of known amino acid content). Total amounts of amino acids extracted increased with both time and temperature; however, the distribution shifted notably due to the destruction of the amino acids with charged or polar side chains at the higher temperatures. The pure bovine serum albumin solution and JSC Mars 1A also showed lower yields than the Atacama and Antarctic extractions suggesting that SCWE may be less effective at hydrolyzing large or aggregated proteins. Changing solvent from water to a dilute (10 mM) HCl solution allowed total extraction efficiencies comparable to the higher temperature/time combinations while using the lowest temperature/time (185°C/20 min). The dilute HCl extractions also did not lead to the shift in amino acid distribution observed at the higher temperatures. Additionally, adding sodium perchlorate salt to the extraction did not interfere with recoveries. Native magnetite in the JSC Mars-1A may have been responsible for destruction of glycine, as evidenced by its uncharacteristic decrease as the temperature/time of extraction increased. This work shows that SCWE can extract high yields of native amino acids out of Mars analog soils with minimal disruption of the distribution of those amino acids, even in the presence of a perchlorate salt. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stability of tranexamic acid in 0.9% sodium chloride, stored in type 1 glass vials and ethylene/propylene copolymer plastic containers.

PubMed

McCluskey, Susan V; Sztajnkrycer, Matthew D; Jenkins, Donald A; Zietlow, Scott P; Berns, Kathleen S; Park, Myung S

2014-01-01

Tranexamic acid has recently been demonstrated to decrease all-cause mortality and deaths due to hemorrhage in trauma patients. The optimal administration of tranexamic acid is within one hour of injury, but not more than three hours from the time of injury. To aid with timely administration, a premixed solution of 1 gram tranexamic acid and 0.9% sodium chloride was proposed to be stocked as a medication in both the aeromedical transport helicopters and Emergency Department at Mayo Clinic Hospital--Rochester Saint Marys Campus. Since no published stability data exists for tranexamic acid diluted with 0.9% sodium chloride, this study was undertaken to determine the stability of tranexamic acid diluted with 0.9% sodium chloride while being stored in two types of containers. Stability was determined through the use of a stability-indicating high-performance liquid reverse phase chromatography assay, pH, and visual tests. Tranexamic acid solutions of 1 gram in 0.9% sodium chloride 65 mL were studied at predetermined intervals for 90 days in ethylene/propylene copolymer plastic containers, protected from light, and at both controlled room and refrigerated temperatures. Tranexamic acid solutions of 1 gram in 0.9% sodium chloride 50 mL were studied at predetermined intervals for 180 days in clear Type 1 borosilicate glass vials sealed with intact elastomeric, Flourotec-coated stoppers, stored protected from light at controlled room temperature. Solutions stored in the ethylene/propylene copolymer plastic containers at both storage temperatures maintained at least 98% of initial potency throughout the 90-day study period. Solutions stored in glass vials at controlled room temperature maintained at least 92% of initial potency throughout the 180-day study period. Visual and pH tests revealed stable, clear, colorless, and particulate-free solutions throughout the respective study periods.

New connection method for isolating and disinfecting intraluminal path during peritoneal dialysis solution-exchange procedures.

PubMed

Grabowy, R S; Kelley, R; Richter, S G; Bousquet, G G; Carr, K L

1998-01-01

Microbiological data have been collected on the performance of a new method of isolating and disinfecting the intraluminal path at the connect/disconnect site of a peritoneal dialysis (PD)-exchange pathway. High-temperature moist-heat (HTMH) disinfection is accomplished by a new device that uses microwave energy to heat the solution contained in the pressure-tight inner lumen of PD connector pairs between the transfer-set connector-clamp and the bag-connector break-away seal. An 85 degrees C (S.D. = 2.4 degrees C, n = 10) rise in solution temperature is seen in 12 seconds, thus yielding temperatures under pressure well over 100 degrees C with starting temperatures of 25 degrees C. Connector pairs were prepared by inoculation of a solution suspension containing at least 10(6) colony-forming units (CFU) of a test micro-organism. Approximately 0.4 mL of solution was contained within the mated connector pair. Using standard D-value determination methods, data were obtained for surviving organisms versus five exposure times and a positive control to obtain a population reduction curve. Four micro-organisms (S. epidermidis, P. aeruginosa, C. albicans, and A. niger) recognized to be among the most prevalent or problematic in causing peritonitis were tested. After microwave heating, the treated solution was aseptically withdrawn from the connector pair using a needle and syringe, plated in growth media, and incubated. Population counts of CFUs after incubation were used to establish survival curves. Results showed a tenfold population reduction in less than 3 seconds for all organisms tested. A 30-second cycle time safely achieves a > 10(8) population-reduction for bacteria and yeast organisms, and a > 10(7) population reduction for fungi. One potential benefit of using this new intraluminal disinfection method is that it may help reduce peritonitis resulting from the even more problematic pathogens such as the gram-negative bacteria and fungal organisms.

Changes in apple liquid phase concentration throughout equilibrium in osmotic dehydration.

PubMed

Barat, J M; Barrera, C; Frías, J M; Fito, P

2007-03-01

Previous results on apple tissue equilibration during osmotic dehydration showed that, at very long processing times, the solute concentrations of the fruit liquid phase and the osmotic solution were the same. In the present study, changes in apple liquid phase composition throughout equilibrium in osmotic dehydration were analyzed and modeled. Results showed that, by the time osmosed samples reached the maximum weight and volume loss, solute concentration of the fruit liquid phase was higher than that of the osmotic solution. The reported overconcentration could be explained in terms of the apple structure shrinkage that occurred during the osmotic dehydration with highly concentrated osmotic solutions due to the elastic response of the food structure to the loss of water and intake of solutes. The fruit liquid phase overconcentration rate was observed to depend on the concentration of the osmotic solution, the processing temperature, the sample size, and shape of the cellular tissue.

Modeling Solar Zenith Angle Effects on the Polar Wind

NASA Technical Reports Server (NTRS)

Glocer, A; Kitamura, N.; Toth, G; Gombosi, T.

2012-01-01

We use the Polar Wind Outflow Model (PWOM) to study the geomagnetically quiet conditions in the polar cap during solar maximum. The PWOM solves the gyrotropic transport equations for O+, H+, and He+ along several magnetic field lines in the polar region in order to reconstruct the full 3D solution. We directly compare our simulation results to the data based empirical model of Kitamura et al. (2011) of electron density which is based on 63 months of Akebono satellite observations. The modeled ion and electron temperatures are also compared with a statistical compilation of quiet time data obtained by the EISCAT Svalbard Radar (ESR) and Intercosmos Satellites. The data and model agree reasonably well, albeit with some differences. This study shows that photoelectrons play an important role in explaining the differences between sunlit and dark results of electron density, ion composition, as well as ion and electron temperatures of the quiet time polar wind solution. Moreover, these results provide an initial validation of the PWOM s ability to model the quiet time "background" solution.

Effect of ageing time and temperature on corrosion behaviour of aluminum alloy 2014

NASA Astrophysics Data System (ADS)

Gadpale, Vikas; Banjare, Pragya N.; Manoj, Manoranjan Kumar

2018-03-01

In this paper, the effect of corrosion behaviour of aluminium alloy 2014 were studied by potentiodynamic polarization in 1 mole of NaCl solution of aged sample. The experimental testing results concluded that, corrosion resistance of Aluminum alloy 2014 degraded with the increasing the temperature (150°C & 200°C) and time of ageing. Corroded surface of the aged specimens was tested under optical microscopes for microstructures for phase analysis. Optical micrographs of corroded surfaces showed general corrosion and pitting corrosion. The corrosion resistance of lower ageing temperature and lower ageing time is higher because of its fine distribution of precipitates in matrix phase.

Structural Changes in PEO-PPO-PEO Gels Induced by Methylparaben and Dexamethasone Observed Using Time-Resolved SAXS

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

Meznarich, Norman A.K.; Juggernauth, K Anne; Batzli, Kiersten M

2011-11-17

Aqueous solutions of polyoxyethylene-polyoxypropylene-polyoxyethylene (PEO-PPO-PEO) triblock copolymers (commercially available as Pluronic surfactants) micellize and structurally arrange into cubic quasicrystalline lattices as their temperature is raised. This structural evolution is seen macroscopically as a gelation, and the presence of these ordered phases can be controlled through both polymer concentration and temperature. The presence of added solutes within the dispersions can also affect the onset and kinetics of structure formation. Here we investigate the structures formed in Pluronic F127 solutions ranging from 20 to 30% with two pharmaceutical additives [methylparaben (MP) and dexamethasone (DX)] using small-angle X-ray scattering (SAXS). We observe bothmore » the progressive evolution and breakdown of these structures as the temperature is increased from 0 to 80 °C. Additionally, we conducted time-resolved SAXS measurements to elucidate the kinetics of the structural evolution. On the basis of the evolution of scattering peaks as the samples were being heated, we suggest that added MP changes the nucleation behavior of fcc phases within the sample from a heterogeneous process to a more homogeneous distribution of nucleated species. MP and DX also stabilize the micelle lattices, allowing them to persevere at higher temperatures. We observed the unusual result that the presence of DX caused the primary peaks of the structure factor to be suppressed, while preserving the higher order peaks. The primary peaks reappeared at the highest temperatures tested.« less

Extraction of magnesium from calcined dolomite ore using hydrochloric acid leaching

NASA Astrophysics Data System (ADS)

Royani, Ahmad; Sulistiyono, Eko; Prasetiyo, Agus Budi; Subagja, Rudi

2018-05-01

Magnesium is widely used in varieties industrial sector. Dolomite is one source of magnesium besides seawater. The extraction of magnesium from dolomite ores can be done by leaching process. In this work, the dolomite leaching to extract magnesium by hydrochloric acid was investigated. The leaching experiments were performed in a spherical glass batch reactor having a capacity of 1000 ml. The effects of the stirring speed, acid concentration, reaction temperature and liquid-solid ratio for each reaction time of 1; 2; and 3 h on the Mg leaching have been evaluated. 5 ml of solution sample were collected from the leached solutions, then it was filtered prior to analysis by ICP OES. The experimental results show that the magnesium extraction increases along with the increase of acid concentration, liquid-solid ratio and temperature. The optimum conditions for magnesium extraction were achieved at temperature 75 °C, extraction time 3 h, the HCl concentration of 2 M, the liquid-solid ratio 20 ml/g and stirring speed of 400 rpm. At this condition 98, 82 % of magnesium were extracted from dolomite. The conclusion obtained from this leaching process is that the magnesium can be extracted from dolomite by using hydrochloric acid solutions.

Dynamics of human serum albumin studied by acoustic relaxation spectroscopy.

PubMed

Hushcha, T; Kaatze, U; Peytcheva, A

Sonic absorption spectra of solutions of human serum albumin (SA) in water and in aqueous phosphate buffer systems have been measured between 0.2 and 2000 MHz at different temperatures (15-35 degrees C), pH values (1.8-12.3), and protein concentrations (1-40 g/L). Several spectra, indicating relaxation processes in the whole frequency range, have been found. The spectra at neutral pH could be fitted well with an analytical function consisting of the asymptotic high frequency absorption and two relaxation contributions, a Debye-type relaxation term with discrete relaxation time and a term with asymmetric continuous distribution of relaxation times. Both relaxation contributions were observed in water and in buffer solutions and increased with protein concentration. The contribution represented by a Debye-type term is practically independent of temperature and was attributed to cooperative conformational changes of the polypeptide chain featuring a relaxation time of about 400 ns. The distribution of the relaxation times corresponding to the second relaxation contribution was characterized by a short time cutoff, between about 0.02 and 0.4 ns depending on temperature, and a long time tail extending to microseconds. Such relaxation behavior was interpreted in terms of solute-solvent interactions reflecting various hydration layers of HSA molecules. At acid and alkaline pH, an additional Debye-type contribution with relaxation time in the range of 30-100 ns exists. It seems to be due to proton transfer reactions of protein side-chain groups. The kinetic and thermodynamic parameters of these processes have been estimated from these first measurements to indicate the potential of acoustic spectra for the investigation of the elementary kinetics of albumin processes. Copyright 2004 Wiley Periodicals, Inc. Biopolymers, 2004

Heat Treatment Devices and Method of Operation Thereof to Produce Dual Microstructure Superalloys Disks

NASA Technical Reports Server (NTRS)

Gayda, John (Inventor); Gabb, Timothy P. (Inventor); Kantzos, Peter T. (Inventor)

2003-01-01

A heat treatment assembly and heat treatment methods are disclosed for producing different microstructures in the bore and rim portions of nickel-based superalloy disks, particu- larly suited for gas turbine applications. The heat treatment assembly is capable of being removed from the furnace and disassembled to allow rapid fan or oil quenching of the disk. For solutioning heat treatments of the disk, temperatures higher than that of this solvus temperature of the disk are used to produce coarse grains in the rim of each disk so as to give maximum creep and dwell crack resistance at the rim service temperature. At the same time, solution temperature lower than the solvus temperature of the disk are provided to produce fine grain in the bore of the disk so as to give maximum strength and low cycle fatigue resistance.

DKDP crystal growth controlled by cooling rate

NASA Astrophysics Data System (ADS)

Xie, Xiaoyi; Qi, Hongji; Shao, Jianda

2017-08-01

The performance of deuterated potassium dihydrogen phosphate (DKDP) crystal directly affects beam quality, energy and conversion efficiency in the Inertial Confinement Fusion（ICF）facility, which is related with the initial saturation temperature of solution and the real-time supersaturation during the crystal growth. However, traditional method to measure the saturation temperature is neither efficient nor accurate enough. Besides, the supersaturation is often controlled by experience, which yields the higher error and leads to the instability during the crystal growth. In this paper, DKDP solution with 78% deuteration concentration is crystallized in different temperatures. We study the relation between solubility and temperature of DKDP and fit a theoretical curve with a parabola model. With the model, the measurement of saturation temperature is simplified and the control precision of the cooling rate is improved during the crystal growth, which is beneficial for optimizing the crystal growth process.

The application of rational approximation in the calculation of a temperature field with a non-linear surface heat-transfer coefficient during quenching for 42CrMo steel cylinder

NASA Astrophysics Data System (ADS)

Cheng, Heming; Huang, Xieqing; Fan, Jiang; Wang, Honggang

1999-10-01

The calculation of a temperature field has a great influence upon the analysis of thermal stresses and stains during quenching. In this paper, a 42CrMo steel cylinder was used an example for investigation. From the TTT diagram of the 42CrMo steel, the CCT diagram was simulated by mathematical transformation, and the volume fraction of phase constituents was calculated. The thermal physical properties were treated as functions of temperature and the volume fraction of phase constituents. The rational approximation was applied to the finite element method. The temperature field with phase transformation and non-linear surface heat-transfer coefficients was calculated using this technique, which can effectively avoid oscillationin the numerical solution for a small time step. The experimental results of the temperature field calculation coincide with the numerical solutions.

Solution to the differential equation for combined radiative and convective cooling for a heated sphere

NASA Technical Reports Server (NTRS)

Wills, F. D.; Katz, L.

1976-01-01

A solution is presented for the differential equation relating the combined effects of radiative and forced convective cooling for a heated sphere. The equation has the form where T and t are the variables temperature and time, respectively, and K sub o, T sub o, and H are constants. The solution can be used as a guideline for the design and understanding of space processing phenomena.

Applications of ZVMo NMR spectroscopy. 17. ZVMo and UN relaxation time measurements confirming that (Mo(CN)8)U is dodecahedral in aqueous solution

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

Brownlee, R.T.; Shehan, B.P.; Wedd, A.G.

1987-07-01

Variable-temperature NMR line width measurements of ZVMo and UN in aqueous solutions of K4(Mo(CN)8) x 2H2O indicate that the stereochemistry of the (Mo(CN)8)U ion in solution is dodecahedral. A value for the ZVMo quadrupole coupling constant of 3.61 MHz is obtained. 27 references, 1 figure, 1 table.

Mechanochemical stabilization and sintering of nanocrystalline the (ZrO2)0.97 (Y2O3)0.03 solid solution from pure oxides

NASA Astrophysics Data System (ADS)

Rendtorff, N. M.; Suárez, G.; Sakka, Y.; Aglietti, E. F.

2011-10-01

The mechanochemical activation processing has proved to be an effective technique to enhance a solid-state reaction at relatively low temperatures. In such a process, the mechanical effects of milling, such as reduction of particle size and mixture homogenization, are accompanied by chemical effects, such as partial decomposition of salts or hydroxides resulting in very active reactants. The objective of the present work is to obtain (ZrO2)0.97(Y2O3)0.03 nanocrystalline tetragonal solid solution powders directly using a high energy milling on a mixture of the pure oxides. A second objective is to evaluate the efficiency of the processing proposed and to characterize both textural and structural evolution of the mixtures during the milling processes and throughout posterior low temperature treatments. The Textural and structural evolution were studied by XRD analysis, specific area measurements (BET) and SEM. Firstly a decrease of the crystallinity of the reactants was observed, followed by the disappearance of Y2O3 diffraction peaks and the partial appearance of the tetragonal phase at room temperature. The solid solution proportion was increased with the high energy milling time, obtaining complete stabilization of the tetragonal solid solution with long milling treatments (60 min).The obtained powders were uniaxially pressed and sintered at different temperatures (600-1400°C) the influence of the milling time was correlated with the sinterization degree and final crystalline composition of the materials. Finally, fully stabilized nanocrystalline zirconia materials were obtained satisfactorily by the proposed method.

Stress-induced, time-dependent fracture closure at hydrothermal conditions

USGS Publications Warehouse

Beeler, N.M.; Hickman, S.H.

2004-01-01

Time-dependent closure of fractures in quartz was measured in situ at 22-530??C temperature and 0.1-150 MPa water pressure. Unlike previous crack healing and rock permeability studies, in this study, fracture aperture is monitored directly and continuously using a windowed pressure vessel, a long-working-distance microscope, and reflected-light interferometry. Thus the fracture volume and geometry can be measured as a function of time, temperature, and water pressure. Relatively uniform closure occurs rapidly at temperatures and pressures where quartz becomes significantly soluble in water. During closure the aperture is reduced by as much as 80% in a few hours. We infer that this closure results from the dissolution of small particles or asperities that prop the fracture open. The driving force for closure via dissolution of the prop is the sum of three chemical potential terms: (1) the dissolution potential, proportional to the logarithm of the degree of undersaturation of the solution; (2) the coarsening potential, proportional to the radius of curvature of the prop; and (3) the pressure solution potential, proportional to the effective normal stress at the contact between propping particles and the fracture wall. Our observations suggest that closure is controlled by a pressure solution-like process. The aperture of dilatant fractures and microcracks in the Earth that are similar to those in our experiments, such as ones generated from thermal stressing or brittle failure during earthquake rupture and slip, will decrease rapidly with time, especially if the macroscopic stress is nonhydrostatic.

Stress-induced, time-dependent fracture closure at hydrothermal conditions

NASA Astrophysics Data System (ADS)

Beeler, N. M.; Hickman, S. H.

2004-02-01

Time-dependent closure of fractures in quartz was measured in situ at 22-530°C temperature and 0.1-150 MPa water pressure. Unlike previous crack healing and rock permeability studies, in this study, fracture aperture is monitored directly and continuously using a windowed pressure vessel, a long-working-distance microscope, and reflected-light interferometry. Thus the fracture volume and geometry can be measured as a function of time, temperature, and water pressure. Relatively uniform closure occurs rapidly at temperatures and pressures where quartz becomes significantly soluble in water. During closure the aperture is reduced by as much as 80% in a few hours. We infer that this closure results from the dissolution of small particles or asperities that prop the fracture open. The driving force for closure via dissolution of the prop is the sum of three chemical potential terms: (1) the dissolution potential, proportional to the logarithm of the degree of undersaturation of the solution; (2) the coarsening potential, proportional to the radius of curvature of the prop; and (3) the pressure solution potential, proportional to the effective normal stress at the contact between propping particles and the fracture wall. Our observations suggest that closure is controlled by a pressure solution-like process. The aperture of dilatant fractures and microcracks in the Earth that are similar to those in our experiments, such as ones generated from thermal stressing or brittle failure during earthquake rupture and slip, will decrease rapidly with time, especially if the macroscopic stress is nonhydrostatic.

Enhancing uranium uptake by amidoxime adsorbent in seawater: An investigation for optimum alkaline conditioning parameters

DOE PAGES

Das, Sadananda; Tsouris, Costas; Zhang, Chenxi; ...

2015-09-07

A high-surface-area polyethylene-fiber adsorbent (AF160-2) has been developed at the Oak Ridge National Laboratory by radiation-induced graft polymerization of acrylonitrile and itaconic acid. The grafted nitriles were converted to amidoxime groups by treating with hydroxylamine. The amidoximated adsorbents were then conditioned with potassium hydroxide (KOH) by varying different reaction parameters such as KOH concentration (0.2, 0.44, and 0.6 M), duration (1, 2, and 3 h), and temperature (60, 70, and 80 °C). Adsorbent screening was then performed with simulated seawater solutions containing sodium chloride and sodium bicarbonate, at concentrations found in seawater, and uranium nitrate at a uranium concentration ofmore » ~7–8 ppm and pH 8. Fourier transform infrared spectroscopy and solid-state NMR analyses indicated that a fraction of amidoxime groups was hydrolyzed to carboxylate during KOH conditioning. The uranium adsorption capacity in the simulated seawater screening solution gradually increased with conditioning time and temperature for all KOH concentrations. It was also observed that the adsorption capacity increased with an increase in concentration of KOH for all the conditioning times and temperatures. AF160-2 adsorbent samples were also tested with natural seawater using flow-through experiments to determine uranium adsorption capacity with varying KOH conditioning time and temperature. Based on uranium loading capacity values of several AF160-2 samples, it was observed that changing KOH conditioning time from 3 to 1 h at 60, 70, and 80 °C resulted in an increase of the uranium loading capacity in seawater, which did not follow the trend found in laboratory screening with stimulated solutions. Longer KOH conditioning times lead to significantly higher uptake of divalent metal ions, such as calcium and magnesium, which is a result of amidoxime conversion into less selective carboxylate. The scanning electron microscopy showed that long conditioning times may also lead to adsorbent degradation.« less

Enhancing Uranium Uptake by Amidoxime Adsorbent in Seawater: An investigation for optimum alkaline conditioning parameters

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

Das, S.; Tsouris, Constantinos; Zhang, C.

2016-04-20

A high-surface-area polyethylene-fiber adsorbent (AF160-2) has been developed at the Oak Ridge National Laboratory (ORNL) by radiation-induced graft polymerization of acrylonitrile and itaconic acid. The grafted nitriles were converted to amidoxime groups by treating with hydroxylamine. The amidoximated adsorbents were then conditioned with potassium hydroxide (KOH) by varying different reaction parameters such as KOH concentration (0.2, 0.44, and 0.6 M), duration (1, 2, and 3 h), and temperature (60, 70, and 80 ºC). Adsorbent screening was then performed with simulated seawater solutions containing sodium chloride and sodium bicarbonate, at concentrations found in seawater, and uranium nitrate at a uranium concentrationmore » of ~ 7-8 ppm and pH 8. FTIR and solid state NMR indicated that a fraction of amidoxime groups was hydrolyzed to carboxylate during KOH conditioning. The uranium adsorption capacity in the simulated seawater screening solution gradually increased with conditioning time and temperature for all KOH concentrations. It was also observed that the adsorption capacity increased with an increase in concentration of KOH for all the conditioning times and temperatures. AF160-2 adsorbent samples were also tested with natural seawater using flow-through experiments to determine uranium adsorption capacity with varying KOH conditioning time and temperature. Based on uranium loading capacity values of several AF160-2 samples, it was observed that changing KOH conditioning time from 3 to 1 h at 60, 70, and 80 ºC resulted in increase of the uranium loading capacity in seawater, which did not follow the trend found in laboratory screening with stimulated solutions. Longer KOH conditioning times lead to significantly higher uptake of divalent metal ions, such as calcium and magnesium, which is a result of amidoxime conversion into less selective carboxylate. Scanning electron microscopy showed that long conditioning times may also lead to adsorbent degradation« less

The Effect of Stabilization Heat Treatments on the Tensile and Creep Behavior of an Advanced Nickel-Based Disk Alloy

NASA Technical Reports Server (NTRS)

Gayda, John

2003-01-01

As part of NASA s Advanced Subsonic Technology Program, a study of stabilization heat treatment options for an advanced nickel-base disk alloy, ME 209, was performed. Using a simple, physically based approach, the effect of stabilization heat treatments on tensile and creep properties was analyzed in this paper. Solutions temperature, solution cooling rate, and stabilization temperature/time were found to have a significant impact on tensile and creep properties. These effects were readily quantified using the following methodology. First, the effect of solution cooling rate was assessed to determine its impact on a given property. The as-cooled property was then modified by using two multiplicative factors which assess the impact of solution temperature and stabilization parameters. Comparison of experimental data with predicted values showed this physically based analysis produced good results that rivaled the statistical analysis employed, which required numerous changes in the form of the regression equation depending on the property and temperature in question. As this physically based analysis uses the data for input, it should be noted that predictions which attempt to extrapolate beyond the bounds of the data must be viewed with skepticism. Future work aimed at expanding the range of the stabilization/aging parameters explored in this study would be highly desirable, especially at the higher solution cooling rates.

Fluidized bed gasification of extracted coal

DOEpatents

Aquino, D.C.; DaPrato, P.L.; Gouker, T.R.; Knoer, P.

1984-07-06

Coal or similar carbonaceous solids are extracted by contacting the solids in an extraction zone with an aqueous solution having a pH above 12.0 at a temperature between 65/sup 0/C and 110/sup 0/C for a period of time sufficient to remove bitumens from the coal into said aqueous solution, and the extracted solids are then gasified at an elevated pressure and temperature in a fluidized bed gasification zone (60) wherein the density of the fluidized bed is maintained at a value above 160 kg/m/sup 3/. In a preferred embodiment of the invention, water is removed from the aqueous solution in order to redeposit the extracted bitumens onto the solids prior to the gasification step. 2 figs., 1 tab.

A simplified heat transfer model for predicting temperature change inside food package kept in cold room.

PubMed

Raval, A H; Solanki, S C; Yadav, Rajvir

2013-04-01

A simple analytical heat flow model for a closed rectangular food package containing fruits or vegetables is proposed for predicting time temperature distribution during transient cooling in a controlled environment cold room. It is based on the assumption of only conductive heat transfer inside a closed food package with effective thermal properties, and convective and radiative heat transfer at the outside of the package. The effective thermal conductivity of the food package is determined by evaluating its effective thermal resistance to heat conduction in the packages. Food packages both as an infinite slab and a finite slab have been investigated. The finite slab solution has been obtained as the product of three infinite slab solutions describe in ASHRAE guide and data book. Time temperature variation has been determined and is presented graphically. The cooling rate and the half cooling time were also obtained. These predicted values, are compared with the experimentally measured values for both the finite and infinite closed packages containing oranges. An excellent agreement between them validated the simple proposed model.

Real-time temperature monitoring during radiofrequency treatments on ex-vivo animal model by fiber Bragg grating sensors

NASA Astrophysics Data System (ADS)

Palumbo, Giovanna; Tosi, Daniele; Schena, Emiliano; Massaroni, Carlo; Ippolito, Juliet; Verze, Paolo; Carlomagno, Nicola; Tammaro, Vincenzo; Iadicicco, Agostino; Campopiano, Stefania

2017-05-01

Fiber Bragg Grating (FBG) sensors applied to bio-medical procedures such as surgery and rehabilitation are a valid alternative to traditional sensing techniques due to their unique characteristics. Herein we propose the use of FBG sensor arrays for accurate real-time temperature measurements during multi-step RadioFrequency Ablation (RFA) based thermal tumor treatment. Real-time temperature monitoring in the RF-applied region represents a valid feedback for the success of the thermo-ablation procedure. In order to create a thermal multi-point map around the tumor area to be treated, a proper sensing configuration was developed. In particular, the RF probe of a commercial medical instrumentation, has been equipped with properly packaged FBGs sensors. Moreover, in order to discriminate the treatment areas to be ablated as precisely as possible, a second array 3.5 cm long, made by several FBGs was used. The results of the temperature measurements during the RFA experiments conducted on ex-vivo animal liver and kidney tissues are presented herein. The proposed FBGs based solution has proven to be capable of distinguish different and consecutive discharges and for each of them, to measure the temperature profile with a resolution of 0.1 °C and a minimum spatial resolution of 5mm. Based upon our experiments, it is possible to confirm that the temperature decreases with distance from a RF peak ablation, in accordance with RF theory. The proposed solution promises to be very useful for the surgeon because a real-time temperature feedback allows for the adaptation of RFA parameters during surgery and better delineates the area under treatment.

Environmental temperature affects the dynamics of ingestion in the nectivorous ant Camponotus mus.

PubMed

Falibene, Agustina; Josens, Roxana

2014-12-01

Environmental temperature influences physiology and behavior in animals in general and is particularly determinant in ectotherms. Not least because temperature defines metabolism and body temperature, muscle activity in insects also strongly depends on this factor. Here, we analyzed how environmental temperature influences the dynamics of ingestion due to its effect on the sucking pump muscles in the nectivorous ants Camponotus mus. Feeding behavior and sucking pump activity during sucrose solution ingestion were first recorded in a natural environment in an urban setting throughout the day and in different seasons. Then, controlled temperature experiments were performed in the laboratory. In both situations, feeding time decreased and pumping frequency increased with temperature. However, different pumping frequencies under a same temperature were also observed in different seasons. Besides, in the laboratory, the volume of solution ingested increased with temperature. Consequently, intake rate increased when temperature rose. This change was exclusively promoted by a variation in the pumping frequency while volume taken in per pump contraction was not affected by temperature. In summary, environmental temperature modified the dynamics of ingestion and feeding behavior by directly affecting pumping frequency. Copyright © 2014 Elsevier Ltd. All rights reserved.

Adsorption Effectivity Test of Andisols Clay-Zeolite (ACZ) Composite as Chromium Hexavalent (Cr(VI)) Ion Adsorbent

NASA Astrophysics Data System (ADS)

Pranoto; Masykur, A.; Nugroho, Y. A.

2018-03-01

Adsorption of chromium hexavalent (Cr(VI)) ion in aqueous solution was investigated. This research was purposed to study the influence of the composition of ACZ, temperature activation, and contact time against adsorption capacity of Cr(VI) ion in aqueous solution. Determination of adsorption effectivity using several parameter such as composition variation of ACZ, contact time, pH, activation temperature, and concentration. In this research, andisol clay and zeolite has been activated with NaOH 3 M and 1 M, respectively. Temperature variation used 100, 200, and 400°C. While composition variation ACZ used 0:100, 25:75, 50:50, 75:25, 100:0. The pH variation was used 2 – 6 and concentration variation using 2, 4, 6, 8, 10, and 12 ppm. Characterization in this research used such as UV-Vis, Surface Area Analyzer (SAA) and Acidity Analysis. Result of this research is known that optimum composition of ACZ was 50:50 with calcination temperature 100°C. Optimum adsorption of Cr(VI) at pH 4 with removal percentage 76.10 % with initial concentration 2 ppm and adsorption capacity is 0.16 mg/g. Adsorption isotherm following freundlich isotherm with value Kf = 0.17 mg/g and value n is 0.963. Based on results, ACZ composite can be used as Cr(VI) ion adsorbents in aqueous solutions.

Adaptive Finite Element Methods for Continuum Damage Modeling

NASA Technical Reports Server (NTRS)

Min, J. B.; Tworzydlo, W. W.; Xiques, K. E.

1995-01-01

The paper presents an application of adaptive finite element methods to the modeling of low-cycle continuum damage and life prediction of high-temperature components. The major objective is to provide automated and accurate modeling of damaged zones through adaptive mesh refinement and adaptive time-stepping methods. The damage modeling methodology is implemented in an usual way by embedding damage evolution in the transient nonlinear solution of elasto-viscoplastic deformation problems. This nonlinear boundary-value problem is discretized by adaptive finite element methods. The automated h-adaptive mesh refinements are driven by error indicators, based on selected principal variables in the problem (stresses, non-elastic strains, damage, etc.). In the time domain, adaptive time-stepping is used, combined with a predictor-corrector time marching algorithm. The time selection is controlled by required time accuracy. In order to take into account strong temperature dependency of material parameters, the nonlinear structural solution a coupled with thermal analyses (one-way coupling). Several test examples illustrate the importance and benefits of adaptive mesh refinements in accurate prediction of damage levels and failure time.

An analytical investigation of transient effects on rewetting of heated thin flat plates

NASA Technical Reports Server (NTRS)

Platt, J. A.

1993-01-01

The rewetting of a hot surface is a problem of prime importance in the microgravity application of heat pipe technology, where rewetting controls the time before operations can be re-established following depriming of a heat pipe. Rewetting is also important in the nuclear industry (in predicting behavior during loss-of-coolant accidents), as well as in the chemical and petrochemical industries. Recently Chan and Zhang have presented a closed-form solution for the determination of the rewetting speed of a liquid film flowing over a finite (but long) hot plate subject to uniform heating. Unfortunately, their physically unreasonable initial conditions preclude a meaningful analysis of start-up transient behavior. A new nondimensionalization and closed-form solution for an infinitely-long, uniformly-heated plate is presented. Realistic initial conditions (step change in temperature across the wetting front) and boundary conditions (no spatial temperature gradients infinitely far from the wetting front) are employed. The effects of parametric variation on the resulting simpler closed-form solution are presented and compared with the predictions of a 'quasi-steady' model. The time to reach steady-state rewetting is found to be a strong function of the initial dry-region plate temperature. For heated plates it is found that in most cases the effect of the transient response terms cannot be neglected, even for large times.

Influence of process parameters on the content of biomimetic calcium phosphate coating on titanium: a Taguchi analysis.

PubMed

Thammarakcharoen, Faungchat; Suvannapruk, Waraporn; Suwanprateeb, Jintamai

2014-10-01

In this study, a statistical design of experimental methodology based on Taguchi orthogonal design has been used to study the effect of various processing parameters on the amount of calcium phosphate coating produced by such technique. Seven control factors with three levels each including sodium hydroxide concentration, pretreatment temperature, pretreatment time, cleaning method, coating time, coating temperature and surface area to solution volume ratio were studied. X-ray diffraction revealed that all the coatings consisted of the mixture of octacalcium phosphate (OCP) and hydroxyapatite (HA) and the presence of each phase depended on the process conditions used. Various content and size (-1-100 μm) of isolated spheroid particles with nanosized plate-like morphology deposited on the titanium surface or a continuous layer of plate-like nanocrystals having the plate thickness in the range of -100-300 nm and the plate width in the range of 3-8 μm were formed depending on the process conditions employed. The optimum condition of using sodium hydroxide concentration of 1 M, pretreatment temperature of 70 degrees C, pretreatment time of 24 h, cleaning by ultrasonic, coating time of 6 h, coating temperature of 50 degrees C and surface area to solution volume ratio of 32.74 for producing the greatest amount of the coating formed on the titanium surface was predicted and validated. In addition, coating temperature was found to be the dominant factor with the greatest contribution to the coating formation while coating time and cleaning method were significant factors. Other factors had negligible effects on the coating performance.

Temperature-assisted solute focusing with sequential trap/release zones in isocratic and gradient capillary liquid chromatography: Simulation and experiment

PubMed Central

Groskreutz, Stephen R.; Weber, Stephen G.

2016-01-01

In this work we characterize the development of a method to enhance temperature-assisted on-column solute focusing (TASF) called two-stage TASF. A new instrument was built to implement two-stage TASF consisting of a linear array of three independent, electronically controlled Peltier devices (thermoelectric coolers, TECs). Samples are loaded onto the chromatographic column with the first two TECs, TEC A and TEC B, cold. In the two-stage TASF approach TECs A and B are cooled during injection. TEC A is heated following sample loading. At some time following TEC A’s temperature rise, TEC B’s temperature is increased from the focusing temperature to a temperature matching that of TEC A. Injection bands are focused twice on-column, first on the initial TEC, e.g. single-stage TASF, then refocused on the second, cold TEC. Our goal is to understand the two-stage TASF approach in detail. We have developed a simple yet powerful digital simulation procedure to model the effect of changing temperature in the two focusing zones on retention, band shape and band spreading. The simulation can predict experimental chromatograms resulting from spatial and temporal temperature programs in combination with isocratic and solvent gradient elution. To assess the two-stage TASF method and the accuracy of the simulation well characterized solutes are needed. Thus, retention factors were measured at six temperatures (25–75 °C) at each of twelve mobile phases compositions (0.05–0.60 acetonitrile/water) for homologs of n-alkyl hydroxylbenzoate esters and n-alkyl p-hydroxyphenones. Simulations accurately reflect experimental results in showing that the two-stage approach improves separation quality. For example, two-stage TASF increased sensitivity for a low retention solute by a factor of 2.2 relative to single-stage TASF and 8.8 relative to isothermal conditions using isocratic elution. Gradient elution results for two-stage TASF were more encouraging. Application of two-stage TASF increased peak height for the least retained solute in the test mixture by a factor of 3.2 relative to single-stage TASF and 22.3 compared to isothermal conditions for an injection four-times the column volume. TASF improved resolution and increased peak capacity; for a 12-minute separation peak capacity increased from 75 under isothermal conditions to 146 using single-stage TASF, and 185 for two-stage TASF. PMID:27836226

On the molecular origin of the cooperative coil-to-globule transition of poly(N-isopropylacrylamide) in water† †Electronic supplementary information (ESI) available: Stereochemistry and initial conformation of PNIPAM 30-mer; pair distribution functions of PNIPAM methyl groups; average time of transitions of dihedral angles; distribution of methyl dihedral angles; temperature dependence of average number of hydration water molecules; correlation between hydrogen bonding of water molecules per repeating unit in the FHS and end to end distance and correlation between PNIPAM–water hydrogen bonding and end to end distance. Time evolution of PNIPAM with the first hydration shell: movie FHSpnipam.avi. See DOI: 10.1039/c8cp00537k

PubMed Central

Zaccarelli, E.

2018-01-01

By means of atomistic molecular dynamics simulations we investigate the behaviour of poly(N-isopropylacrylamide), PNIPAM, in water at temperatures below and above the lower critical solution temperature (LCST), including the undercooled regime. The transition between water soluble and insoluble states at the LCST is described as a cooperative process involving an intramolecular coil-to-globule transition preceding the aggregation of chains and the polymer precipitation. In this work we investigate the molecular origin of such cooperativity and the evolution of the hydration pattern in the undercooled polymer solution. The solution behaviour of an atactic 30-mer at high dilution is studied in the temperature interval from 243 to 323 K with a favourable comparison to available experimental data. In the water soluble states of PNIPAM we detect a correlation between polymer segmental dynamics and diffusion motion of bound water, occurring with the same activation energy. Simulation results show that below the coil-to-globule transition temperature PNIPAM is surrounded by a network of hydrogen bonded water molecules and that the cooperativity arises from the structuring of water clusters in proximity to hydrophobic groups. Differently, the perturbation of the hydrogen bond pattern involving water and amide groups occurs above the transition temperature. Altogether these findings reveal that even above the LCST PNIPAM remains largely hydrated and that the coil-to-globule transition is related with a significant rearrangement of the solvent in the proximity of the surface of the polymer. The comparison between the hydrogen bonding of water in the surrounding of PNIPAM isopropyl groups and in the bulk displays a decreased structuring of solvent at the hydrophobic polymer–water interface across the transition temperature, as expected because of the topological extension along the chain of such interface. No evidence of an upper critical solution temperature behaviour, postulated in theoretical and thermodynamics studies of PNIPAM aqueous solution, is observed in the low temperature domain. PMID:29619464

Temperature-assisted solute focusing with sequential trap/release zones in isocratic and gradient capillary liquid chromatography: Simulation and experiment.

PubMed

Groskreutz, Stephen R; Weber, Stephen G

2016-11-25

In this work we characterize the development of a method to enhance temperature-assisted on-column solute focusing (TASF) called two-stage TASF. A new instrument was built to implement two-stage TASF consisting of a linear array of three independent, electronically controlled Peltier devices (thermoelectric coolers, TECs). Samples are loaded onto the chromatographic column with the first two TECs, TEC A and TEC B, cold. In the two-stage TASF approach TECs A and B are cooled during injection. TEC A is heated following sample loading. At some time following TEC A's temperature rise, TEC B's temperature is increased from the focusing temperature to a temperature matching that of TEC A. Injection bands are focused twice on-column, first on the initial TEC, e.g. single-stage TASF, then refocused on the second, cold TEC. Our goal is to understand the two-stage TASF approach in detail. We have developed a simple yet powerful digital simulation procedure to model the effect of changing temperature in the two focusing zones on retention, band shape and band spreading. The simulation can predict experimental chromatograms resulting from spatial and temporal temperature programs in combination with isocratic and solvent gradient elution. To assess the two-stage TASF method and the accuracy of the simulation well characterized solutes are needed. Thus, retention factors were measured at six temperatures (25-75°C) at each of twelve mobile phases compositions (0.05-0.60 acetonitrile/water) for homologs of n-alkyl hydroxylbenzoate esters and n-alkyl p-hydroxyphenones. Simulations accurately reflect experimental results in showing that the two-stage approach improves separation quality. For example, two-stage TASF increased sensitivity for a low retention solute by a factor of 2.2 relative to single-stage TASF and 8.8 relative to isothermal conditions using isocratic elution. Gradient elution results for two-stage TASF were more encouraging. Application of two-stage TASF increased peak height for the least retained solute in the test mixture by a factor of 3.2 relative to single-stage TASF and 22.3 compared to isothermal conditions for an injection four-times the column volume. TASF improved resolution and increased peak capacity; for a 12-min separation peak capacity increased from 75 under isothermal conditions to 146 using single-stage TASF, and 185 for two-stage TASF. Copyright © 2016 Elsevier B.V. All rights reserved.

Extraction of Li and Co from Li-ion Batteries by Chemical Methods

NASA Astrophysics Data System (ADS)

Guzolu, Jafar Sharrivar; Gharabaghi, Mahdi; Mobin, Mohammad; Alilo, Hojat

2017-04-01

In this work a process involving ultrasonic washing and leaching and precipitation was used to recover Li and Co from spent Li-ion batteries. Ultrasonic washing was used to reduce energy consumption and pollution whereas hydrochloric acid was used as leaching reagent. 98 % of Li and nearly 99 % of Co were obtained under optimum condition of 5 M hydrochloric acid solution, temperature of 95 °C, reaction time of 70 min, and solid-liquid ratio of 10 g/L. In this process at first nickel, copper, iron, aluminum, cobalt, and manganese were precipitated from leaching solution using sodium hydroxide at pH f 12.5 and reaction time of 1 h and temperature was 55 °C and all metal recoveries were more than 99 %. In the precipitation experiments, lithium loss was only 18.34 %. In the next stage, white lithium carbonate was precipitated by addition of saturated sodium carbonate solution to the left filtrate from first precipitation step. The purity of the recovered powder of lithium was 95 %.

A computer program for the simulation of heat and moisture flow in soils

NASA Technical Reports Server (NTRS)

Camillo, P.; Schmugge, T. J.

1981-01-01

A computer program that simulates the flow of heat and moisture in soils is described. The space-time dependence of temperature and moisture content is described by a set of diffusion-type partial differential equations. The simulator uses a predictor/corrector to numerically integrate them, giving wetness and temperature profiles as a function of time. The simulator was used to generate solutions to diffusion-type partial differential equations for which analytical solutions are known. These equations include both constant and variable diffusivities, and both flux and constant concentration boundary conditions. In all cases, the simulated and analytic solutions agreed to within the error bounds which were imposed on the integrator. Simulations of heat and moisture flow under actual field conditions were also performed. Ground truth data were used for the boundary conditions and soil transport properties. The qualitative agreement between simulated and measured profiles is an indication that the model equations are reasonably accurate representations of the physical processes involved.

A Malaria Transmission Model with Temperature-Dependent Incubation Period.

PubMed

Wang, Xiunan; Zhao, Xiao-Qiang

2017-05-01

Malaria is an infectious disease caused by Plasmodium parasites and is transmitted among humans by female Anopheles mosquitoes. Climate factors have significant impact on both mosquito life cycle and parasite development. To consider the temperature sensitivity of the extrinsic incubation period (EIP) of malaria parasites, we formulate a delay differential equations model with a periodic time delay. We derive the basic reproduction ratio [Formula: see text] and establish a threshold type result on the global dynamics in terms of [Formula: see text], that is, the unique disease-free periodic solution is globally asymptotically stable if [Formula: see text]; and the model system admits a unique positive periodic solution which is globally asymptotically stable if [Formula: see text]. Numerically, we parameterize the model with data from Maputo Province, Mozambique, and simulate the long-term behavior of solutions. The simulation result is consistent with the obtained analytic result. In addition, we find that using the time-averaged EIP may underestimate the basic reproduction ratio.

Statistical analysis and isotherm study of uranium biosorption by Padina sp. algae biomass.

PubMed

Khani, Mohammad Hassan

2011-06-01

The application of response surface methodology is presented for optimizing the removal of U ions from aqueous solutions using Padina sp., a brown marine algal biomass. Box-Wilson central composite design was employed to assess individual and interactive effects of the four main parameters (pH and initial uranium concentration in solutions, contact time and temperature) on uranium uptake. Response surface analysis showed that the data were adequately fitted to second-order polynomial model. Analysis of variance showed a high coefficient of determination value (R (2)=0.9746) and satisfactory second-order regression model was derived. The optimum pH and initial uranium concentration in solutions, contact time and temperature were found to be 4.07, 778.48 mg/l, 74.31 min, and 37.47°C, respectively. Maximized uranium uptake was predicted and experimentally validated. The equilibrium data for biosorption of U onto the Padina sp. were well represented by the Langmuir isotherm, giving maximum monolayer adsorption capacity as high as 376.73 mg/g.

Preparation of bis-(1(2)H-tetrazol-5-yl)-amine monohydrate

DOEpatents

Naud, Darren L [Los Alamos, NM; Hiskey, Michael A [Los Alamos, NM

2003-05-27

A process of preparing bis-(1(2)H-tetrazol-5-yl)-amine monohydrate is provided including combining a dicyanamide salt, an azide salt and water to form a first reaction mixture, adding a solution of a first strong acid characterized as having a pKa of less than about 1 to said first reaction mixture over a period of time characterized as providing a controlled reaction rate so as to gradually form hydrazoic acid without loss of significant quantities of hydrazoic acid from the solution while heating the first reaction mixture at temperatures greater than about 65.degree. C., heating the resultant reaction mixture at temperatures greater than about 65.degree. C. for a period of time sufficient to substantially completely form a reaction product, treating the reaction product with a solution of a second strong acid to form a product of bis-(1(2)H-tetrazol-5-yl)-amine monohydrate, and, recovering the bis-(1(2)H-tetrazol-5-yl)-amine monohydrate product.

Development of injectable thermogelling chitosan-inorganic phosphate solutions for biomedical applications.

PubMed

Nair, Lakshmi S; Starnes, Trevor; Ko, Jia-Wei Kevin; Laurencin, Cato T

2007-12-01

Thermosetting polymers are attractive candidates for biomedical applications as noninvasive therapeutic delivery vehicles. In the present study, the feasibility of developing a neutral physiological temperature setting injectable formulation based on chitosan and an inorganic phosphate salt have been demonstrated. The in situ gelling system was developed by adding different concentrations of ammonium hydrogen phosphate (AHP) to chitosan solution. The resulting solutions have pH in the range of approximately 7-7.2. The gelling time of the chitosan-AHP solution was determined by incubating the solutions at 37 degrees C. Depending on the concentrations of AHP added, the gelling time varied from 5 min to 30 h at 37 degrees C. Addition of various diluents to chitosan-AHP solution did not significantly change the gelling time of the solutions. The gels were found to be cytocompatible as evidenced from in vitro cytocompatibility evaluation using MC3T3-E1 mouse osteoblast like cells. The feasibility of using the gels as a stem cell carrier vehicle as well as a macromolecular delivery vehicle has been demonstrated.

A Rigorous Temperature-Dependent Stochastic Modelling and Testing for MEMS-Based Inertial Sensor Errors.

PubMed

El-Diasty, Mohammed; Pagiatakis, Spiros

2009-01-01

In this paper, we examine the effect of changing the temperature points on MEMS-based inertial sensor random error. We collect static data under different temperature points using a MEMS-based inertial sensor mounted inside a thermal chamber. Rigorous stochastic models, namely Autoregressive-based Gauss-Markov (AR-based GM) models are developed to describe the random error behaviour. The proposed AR-based GM model is initially applied to short stationary inertial data to develop the stochastic model parameters (correlation times). It is shown that the stochastic model parameters of a MEMS-based inertial unit, namely the ADIS16364, are temperature dependent. In addition, field kinematic test data collected at about 17 °C are used to test the performance of the stochastic models at different temperature points in the filtering stage using Unscented Kalman Filter (UKF). It is shown that the stochastic model developed at 20 °C provides a more accurate inertial navigation solution than the ones obtained from the stochastic models developed at -40 °C, -20 °C, 0 °C, +40 °C, and +60 °C. The temperature dependence of the stochastic model is significant and should be considered at all times to obtain optimal navigation solution for MEMS-based INS/GPS integration.

Infrared Thermography Sensor for Temperature and Speed Measurement of Moving Material.

PubMed

Usamentiaga, Rubén; García, Daniel Fernando

2017-05-18

Infrared thermography offers significant advantages in monitoring the temperature of objects over time, but crucial aspects need to be addressed. Movements between the infrared camera and the inspected material seriously affect the accuracy of the calculated temperature. These movements can be the consequence of solid objects that are moved, molten metal poured, material on a conveyor belt, or just vibrations. This work proposes a solution for monitoring the temperature of material in these scenarios. In this work both real movements and vibrations are treated equally, proposing a unified solution for both problems. The three key steps of the proposed procedure are image rectification, motion estimation and motion compensation. Image rectification calculates a front-parallel projection of the image that simplifies the estimation and compensation of the movement. Motion estimation describes the movement using a mathematical model, and estimates the coefficients using robust methods adapted to infrared images. Motion is finally compensated for in order to produce the correct temperature time history of the monitored material regardless of the movement. The result is a robust sensor for temperature of moving material that can also be used to measure the speed of the material. Different experiments are carried out to validate the proposed method in laboratory and real environments. Results show excellent performance.

Infrared Thermography Sensor for Temperature and Speed Measurement of Moving Material

PubMed Central

Usamentiaga, Rubén; García, Daniel Fernando

2017-01-01

Infrared thermography offers significant advantages in monitoring the temperature of objects over time, but crucial aspects need to be addressed. Movements between the infrared camera and the inspected material seriously affect the accuracy of the calculated temperature. These movements can be the consequence of solid objects that are moved, molten metal poured, material on a conveyor belt, or just vibrations. This work proposes a solution for monitoring the temperature of material in these scenarios. In this work both real movements and vibrations are treated equally, proposing a unified solution for both problems. The three key steps of the proposed procedure are image rectification, motion estimation and motion compensation. Image rectification calculates a front-parallel projection of the image that simplifies the estimation and compensation of the movement. Motion estimation describes the movement using a mathematical model, and estimates the coefficients using robust methods adapted to infrared images. Motion is finally compensated for in order to produce the correct temperature time history of the monitored material regardless of the movement. The result is a robust sensor for temperature of moving material that can also be used to measure the speed of the material. Different experiments are carried out to validate the proposed method in laboratory and real environments. Results show excellent performance. PMID:28524110

On the temperature prediction in a fire escape passage

NASA Astrophysics Data System (ADS)

Casano, G.; Piva, S.

2017-11-01

Fire safety engineering requires a detailed understanding of fire behaviour and of its effects on structures and people. Many factors may condition the fire scenario, as for example, heat transfer between the flame and the boundary structures. Currently advanced numerical codes for the prediction of the fire behaviour are available. However, these solutions often require heavy calculations and long times. In this context analytical solutions can be useful for a fast analysis of simplified schematizations. After that, it is more effective the final utilization of the advanced fire codes. In this contribution, the temperature in a fire escape passage, separated with a thermally resistant wall from a fire room, is analysed. The escape space is included in a building where the neighbouring rooms are at a constant undisturbed temperature. The presence of the neighbouring rooms is considered with an equivalent heat transfer coefficient, in a boundary condition of the third type. An analytical solution is used to predict the temperature distribution during the fire. It allows to obtain useful information on the temperature reached in the escape area in contact with a burning room; it is useful also for a fast choice of the thermal characteristics of a firewall.

Temperature-Dependent Kinetic Study of Ammonia Oxidation Reaction on Gas Diffusion Electrodes in NH 3-Saturated 1 M KOH Solutions

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

Liang, Z.; Song, L.; Ma, Z.

Ammonia oxidation reaction (AOR) is sluggish, especially at ambient temperature. To make kinetic study in electrochemical cell more informative and relevant to the catalysts’ performance in direct ammonia fuel cells (DAFCs) operating at about 100°C, it is desirable to study the AOR kinetics at elevated temperatures. However, ammonia evaporation accelerates with increasing temperature causing decrease of ammonia concentration with time. Here, we show a feasible solution to this issue - let argon gas bubble through concentrated ammonia before entering the electrochemical cell so that the solution can be kept ammonia saturated and oxygen free. Repeatable AOR polarization curves were obtainedmore » at temperatures up to 60°C. The AOR activities are characterized by the average currents at 0.5 V versus RHE measured at 20 mV s-1 in potential cycles below the potential of peak current. For PtIr/C, the PGM mass activities are 25 A g-1 at 25°C and 225 A g -1 at 60°C. The results for Pt/C and Ir/C and discussion of the causes for their distinct kinetic behavior will be presented at the meeting.« less

Profile modifications in laser-driven temperature fronts using flux-limiters and delocalization models

NASA Astrophysics Data System (ADS)

Colombant, Denis; Manheimer, Wallace; Busquet, Michel

2004-11-01

A simple steady-state model using flux-limiters by Day et al [1] showed that temperature profiles could formally be double-valued. Stability of temperature profiles in laser-driven temperature fronts using delocalization models was also discussed by Prasad and Kershaw [2]. We have observed steepening of the front and flattening of the maximum temperature in laser-driven implosions [3]. Following the simple model first proposed in [1], we solve for a two-boundary value steady-state heat flow problem for various non-local heat transport models. For the more complicated models [4,5], we obtain the steady-state solution as the asymptotic limit of the time-dependent solution. Solutions will be shown and compared for these various models. 1.M.Day, B.Merriman, F.Najmabadi and R.W.Conn, Contrib. Plasma Phys. 36, 419 (1996) 2.M.K.Prasad and D.S.Kershaw, Phys. Fluids B3, 3087 (1991) 3.D.Colombant, W.Manheimer and M.Busquet, Bull. Amer. Phys. Soc. 48, 326 (2003) 4.E.M.Epperlein and R.W.Short, Phys. Fluids B3, 3092 (1991) 5.W.Manheimer and D.Colombant, Phys. Plasmas 11, 260 (2004)

Temperature-Dependent Kinetic Study of Ammonia Oxidation Reaction on Gas Diffusion Electrodes in NH 3-Saturated 1 M KOH Solutions

DOE PAGES

Liang, Z.; Song, L.; Ma, Z.; ...

2018-04-01

Ammonia oxidation reaction (AOR) is sluggish, especially at ambient temperature. To make kinetic study in electrochemical cell more informative and relevant to the catalysts’ performance in direct ammonia fuel cells (DAFCs) operating at about 100°C, it is desirable to study the AOR kinetics at elevated temperatures. However, ammonia evaporation accelerates with increasing temperature causing decrease of ammonia concentration with time. Here, we show a feasible solution to this issue - let argon gas bubble through concentrated ammonia before entering the electrochemical cell so that the solution can be kept ammonia saturated and oxygen free. Repeatable AOR polarization curves were obtainedmore » at temperatures up to 60°C. The AOR activities are characterized by the average currents at 0.5 V versus RHE measured at 20 mV s-1 in potential cycles below the potential of peak current. For PtIr/C, the PGM mass activities are 25 A g-1 at 25°C and 225 A g -1 at 60°C. The results for Pt/C and Ir/C and discussion of the causes for their distinct kinetic behavior will be presented at the meeting.« less

Formation of bubbly horizon in liquid-saturated porous medium by surface temperature oscillation.

PubMed

Goldobin, Denis S; Krauzin, Pavel V

2015-12-01

We study nonisothermal diffusion transport of a weakly soluble substance in a liquid-saturated porous medium in contact with a reservoir of this substance. The surface temperature of the porous medium half-space oscillates in time, which results in a decaying solubility wave propagating deep into the porous medium. In this system, zones of saturated solution and nondissolved phase coexist with ones of undersaturated solution. The effect is first considered for the case of annual oscillation of the surface temperature of water-saturated ground in contact with the atmosphere. We reveal the phenomenon of formation of a near-surface bubbly horizon due to temperature oscillation. An analytical theory of the phenomenon is developed. Further, the treatment is extended to the case of higher frequency oscillations and the case of weakly soluble solids and liquids.

Pressure in isochoric systems containing aqueous solutions at subzero Centigrade temperatures

PubMed Central

Șerban, Alexandru; Rubinsky, Boris

2017-01-01

Objective Preservation of biological materials at subzero Centigrade temperatures, cryopreservation, is important for the field of tissue engineering and organ transplantation. Our group is studying the use of isochoric (constant volume) systems of aqueous solution for cryopreservation. Previous studies measured the pressure-temperature relations in aqueous isochoric systems in the temperature range from 0°C to – 20°C. The goal of this study is to expand the pressure-temperature measurement beyond the range reported in previous publications. Materials and methods To expand the pressure-temperature measurements beyond the previous range, we have developed a new isochoric device capable of withstanding liquid nitrogen temperatures and pressures of up to 413 MPa. The device is instrumented with a pressure transducer than can monitor and record the pressures in the isochoric chamber in real time. Measurements were made in a temperature range from – 5°C to liquid nitrogen temperatures for various solutions of pure water and Me2SO (a chemical additive used for protection of biological materials in a frozen state and for vitrification (glass formation) of biological matter). Undissolved gaseous are is carefully removed from the system. Results Temperature-pressure data from – 5°C to liquid nitrogen temperature for pure water and other solutions are presented in this study. Following are examples of some, temperature-pressure values, that were measured in an isochoric system containing pure water: (- 20°C, 187 MPa); (-25°C, 216 MPa); (- 30°C, 242.3 MPa); (-180°C, 124 MPa). The data is consistent with the literature, which reports that the pressure and temperature at the triple point, between ice I, ice III and water is, - 21.993°C and 209.9 MPa, respectively. It was surprising to find that the pressure in the isochoric system increases at temperatures below the triple point and remains high to liquid nitrogen temperatures. Measurements of pressure-temperature relations in solutions of pure water and Me2SO in different concentrations show that, for concentrations in which vitrification is predicted, no increase in pressure was measured during rapid cooling to liquid nitrogen temperatures. However, ice formation either during cooling or warming to and from liquid nitrogen temperatures produced an increase in pressure. Conclusions The data obtained in this study can be used to aid in the design of isochoric cryopreservation protocols. The results suggest that the pressure measurement is important in the design of “constant volume” systems and can provide a simple means to gain information on the occurrence of vitrification and devitrification during cryopreservation processes of aqueous solutions in an isochoric system. PMID:28817681

Effects of Etching Time and NaOH Concentration on the Production of Alumina Nanowires Using Porous Anodic Alumina Template

NASA Astrophysics Data System (ADS)

Sadeghpour-Motlagh, M.; Mokhtari-Zonouzi, K.; Aghajani, H.; Kakroudi, M. Ghassemi

2014-06-01

In this work, two-step anodizing of commercial aluminum foil in acid oxalic solution was applied for producing alumina film. Then the anodic alumina film was etched in sodium hydroxide (NaOH) solution resulting dense and aligned alumina nanowires. This procedure leads to splitting of alumina nanotubes. Subsequently nanowires are produced. The effects of NaOH solution concentration (0.2-1 mol/L) and etching time (60-300 s) at constant temperature on characteristic of nanotubes and produced nanowires were investigated using scanning electron microscopy. The results show that an increase in NaOH solution concentration increases the rate of nanowires production and in turn the manipulation process will be more specific.

Water Treatment Using Plasma Discharge with Variation of Electrode Materials

NASA Astrophysics Data System (ADS)

Chanan, N.; Kusumandari; Saraswati, T. E.

2018-03-01

This research studied water treatment using plasma discharge. Plasma generated in this study produced active species that played a role in organic compound decomposition. The plasma reactor consisted of two needle electrodes made from stainless steel, tungsten, aluminium and grafit. It placed approximately 2 mm above the solution and connected with high-AC voltage. A solution of methylene blue used as an organic solution model. Plasma treatment times were 2, 4, 6, 8 and 10 min. The absorbance, temperature and pH of the solution were measured before and after treatment using various electrodes. The best electrode used in plasma discharging for methylene blue absorbance reduction was the graphite electrode, which provided the highest degradation efficiency of 98% at 6 min of treatment time.

Ab Initio Modeling of the Electronic Absorption Spectrum of Previtamin D in Solution

NASA Astrophysics Data System (ADS)

Zhu, Tianyang

To study the solvent effects of water on the previtamin D absorption spectrum, we use the quantum mechanics (QM)/molecular mechanics (MM) method combined with replica-exchange molecular dynamics (REMD). The QM method is applied for the previtamin D molecule and the MM method is used for the water molecules. To enhance conformational sampling of the flexible previtamin D molecule we apply REMD. Based on the REMD structures, we calculate the macroscopic ensemble of the absorption spectrum in solution by time-dependent density functional theory (TDDFT). Comparison between the calculated spectrum in the gas phase and in the solution reveals minor influences of the solvent on the absorption spectrum. In the conventional molecule dynamics simulation, the previtamin D molecule can be trapped by local minimum and cannot overcome energetics barriers when it is calculated at the room temperature. In addition, the higher temperature calculation for the molecule in REMD allows to overcome energetics barriers and to change the structure to other rotational isomers, then switch to the lower temperature and gives a more complete result in the configuration space for the lower temperature.

Attachment of 3-(Aminopropyl)triethoxysilane on silicon oxide surfaces: dependence on solution temperature.

PubMed

Pasternack, Robert M; Rivillon Amy, Sandrine; Chabal, Yves J

2008-11-18

Parameters important to the self-assembly of 3-(aminopropyl)triethoxysilane (APTES) on chemically grown silicon oxide (SiO 2) to form an aminopropyl silane (APS) film have been investigated using in situ infrared (IR) absorption spectroscopy. Preannealing to approximately 70 degrees C produces significant improvements in the quality of the film: the APS film is denser, and the Si-O-Si bonds between the molecules and the SiO 2 surface are more structured and ordered with only a limited number of remaining unreacted ethoxy groups. In contrast, post-annealing the functionalized SiO 2 samples after room temperature reaction with APTES (i.e., ex situ annealing) does not lead to any spectral change, suggesting that post-annealing has no strong effect on the horizontal polymerization as suggested earlier. Both IR and ellipsometry data show that the higher the solution temperature, the denser and thinner the APS layer is for a given immersion time. Finally, the APS layer obtained by preannealing the solution at 70 degrees C exhibits a better stability in deionized water than the APS layer prepared at room temperature.

Secondary relaxations in supercooled and glassy sucrose-borate aqueous solutions.

PubMed

Longinotti, M Paula; Corti, Horacio R; Pablo, Juan J de

2008-10-13

The dielectric relaxation spectra of concentrated aqueous solutions of sucrose-borate mixtures have been measured in the supercooled and glassy regions in the frequency range of 40Hz to 2MHz. The secondary (beta) relaxation process was analyzed in the temperature range 183-233K at water contents between 20 and 30wt%. The relaxation times were obtained, and the activation energy of that process was calculated. In order to assess the effect of borate on the relaxation of disaccharide-water mixtures, we also studied the dielectric behavior of sucrose aqueous solutions in the same range of temperatures and water contents. Our findings support the view that, beyond a water content of approximately 20wt%, the secondary relaxation of water-sucrose and water-sucrose-borate mixtures adopts a universal character that can be explained in terms of a simple exponential function of the temperature scaled by the glass transition temperature (T(g)). The behavior observed for water-sucrose and water-sucrose-borate mixtures is compared with previous results obtained in other water-carbohydrate systems.

Diffusive wave in the low Mach limit for non-viscous and heat-conductive gas

NASA Astrophysics Data System (ADS)

Liu, Yechi

2018-06-01

The low Mach number limit for one-dimensional non-isentropic compressible Navier-Stokes system without viscosity is investigated, where the density and temperature have different asymptotic states at far fields. It is proved that the solution of the system converges to a nonlinear diffusion wave globally in time as Mach number goes to zero. It is remarked that the velocity of diffusion wave is proportional with the variation of temperature. Furthermore, it is shown that the solution of compressible Navier-Stokes system also has the same phenomenon when Mach number is suitably small.

The effect of structural properties on rheological behaviour of starches in binary dimethyl sulfoxide-water solutions

PubMed Central

Ptaszek, Paweł; Dziubiński, Marek; Grzesik, N. Mirosław; Liszka-Skoczylas, Marta

2017-01-01

This research study analysed the rheological properties of potato amylose and potato amylopectin in binary solutions of the following water and dimethyl sulfoxide concentrations: 90% DMSO (1), 80% DMSO (2) and 50% DMSO (3), with preparation methodology involving the dissolution at the temperature of 98°C. The studies of dynamic light scattering on the biopolymer coils and the determination of main relaxation times of the solutions were carried out. For the amylose solutions, the fast relaxation phenomena are predominant. The results of the quality tests of the hysteresis loop showed, that the amylose solutions in the solvents (1) and (2) are rheologically stable and shear-thickened. The amylose solutions in solvents (3) reveal oscillatory alterations of viscosity in the time. Amylopectin solutions are characterized by 80% share of slow relaxation phenomena, very low diffusion coefficients and hydrodynamic radii in the range of 2000 nm. The amylopectin solutions are rheologically unstable. PMID:28152071

Immersion-scanning-tunneling-microscope for long-term variable-temperature experiments at liquid-solid interfaces

NASA Astrophysics Data System (ADS)

Ochs, Oliver; Heckl, Wolfgang M.; Lackinger, Markus

2018-05-01

Fundamental insights into the kinetics and thermodynamics of supramolecular self-assembly on surfaces are uniquely gained by variable-temperature high-resolution Scanning-Tunneling-Microscopy (STM). Conventionally, these experiments are performed with standard ambient microscopes extended with heatable sample stages for local heating. However, unavoidable solvent evaporation sets a technical limit on the duration of these experiments, hence prohibiting long-term experiments. These, however, would be highly desirable to provide enough time for temperature stabilization and settling of drift but also to study processes with inherently slow kinetics. To overcome this dilemma, we propose a STM that can operate fully immersed in solution. The instrument is mounted onto the lid of a hermetically sealed heatable container that is filled with the respective solution. By closing the container, both the sample and microscope are immersed in solution. Thereby solvent evaporation is eliminated and an environment for long-term experiments with utmost stable and controllable temperatures between room-temperature and 100 °C is provided. Important experimental requirements for the immersion-STM and resulting design criteria are discussed, the strategy for protection against corrosive media is described, the temperature stability and drift behavior are thoroughly characterized, and first long-term high resolution experiments at liquid-solid interfaces are presented.

Unusually large Stokes shift for a near-infrared emitting DNA-stabilized silver nanocluster

NASA Astrophysics Data System (ADS)

Ammitzbøll Bogh, Sidsel; Carro-Temboury, Miguel R.; Cerretani, Cecilia; Swasey, Steven M.; Copp, Stacy M.; Gwinn, Elisabeth G.; Vosch, Tom

2018-04-01

In this paper we present a new near-IR emitting silver nanocluster (NIR-DNA-AgNC) with an unusually large Stokes shift between absorption and emission maximum (211 nm or 5600 cm-1). We studied the effect of viscosity and temperature on the steady state and time-resolved emission. The time-resolved results on NIR-DNA-AgNC show that the relaxation dynamics slow down significantly with increasing viscosity of the solvent. In high viscosity solution, the spectral relaxation stretches well into the nanosecond scale. As a result of this slow spectral relaxation in high viscosity solutions, a multi-exponential fluorescence decay time behavior is observed, in contrast to the more mono-exponential decay in low viscosity solution.

In situ study of mass transfer in aqueous solutions under high pressures via Raman spectroscopy: A new method for the determination of diffusion coefficients of methane in water near hydrate formation conditions

USGS Publications Warehouse

Lu, W.J.; Chou, I.-Ming; Burruss, R.C.; Yang, M.Z.

2006-01-01

A new method was developed for in situ study of the diffusive transfer of methane in aqueous solution under high pressures near hydrate formation conditions within an optical capillary cell. Time-dependent Raman spectra of the solution at several different spots along the one-dimensional diffusion path were collected and thus the varying composition profile of the solution was monitored. Diffusion coefficients were estimated by the least squares method based on the variations in methane concentration data in space and time in the cell. The measured diffusion coefficients of methane in water at the liquid (L)-vapor (V) stable region and L-V metastable region are close to previously reported values determined at lower pressure and similar temperature. This in situ monitoring method was demonstrated to be suitable for the study of mass transfer in aqueous solution under high pressure and at various temperature conditions and will be applied to the study of nucleation and dissolution kinetics of methane hydrate in a hydrate-water system where the interaction of methane and water would be more complicated than that presented here for the L-V metastable condition. ?? 2006 Society for Applied Spectroscopy.

Low temperature dissolution flowsheet for Pu metal

DOE PAGES

Daniel, Jr., William E.; Almond, Philip M.; Rudisill, Tracy S.

2017-06-30

The Savannah River National Laboratory was requested to develop a Pu metal dissolution flowsheet at two reduced temperature ranges for implementation in the Savannah River Site H-Canyon facility. The dissolution and H 2 generation rates during Pu metal dissolution were investigated using a dissolving solution at ambient temperature (20–30°C) and for an intermediate temperature of 50–60°C. The Pu metal dissolution rate measured at 57°C was approximately 20 times slower than at boiling (112–116°C). As a result, the dissolution rate at ambient temperature (24°C) was approximately 80 times slower than the dissolution rate at boiling. Hydrogen concentrations were less than detectablemore » (<0.1 vol%).« less

Salt weathering in Egyptian limestone after laboratory simulations with continuous flow of salt solutions at different temperatures

NASA Astrophysics Data System (ADS)

Aly, Nevin; Gomez-Heras, Miguel; Hamed, Ayman; Alvarez de Buergo, Monica

2013-04-01

weathering in Egyptian limestone after laboratory simulations with continuous flow of salt solutions at different temperatures Nevin Aly Mohamed (1), Miguel Gomez - Heras(2), Ayman Hamed Ahmed (1), and Monica Alvarez de Buergo(2). (1) Faculty of Pet. & Min. Engineering- Suez Canal University, Suez, Egypt, (2) Instituto de Geociencias (CSIC-UCM) Madrid. Spain. Limestone is one of the most frequent building stones in Egypt and is used since the time of ancient Egyptians and salt weathering is one of the main threats to its conservation. Most of the limestone used in historical monuments in Cairo is a biomicrite extracted from the Mid-Eocene Mokattam Group. During this work, cylindrical samples (2.4 cm diameter and approx. 4.8 cm length) were subjected, in a purpose-made simulation chamber, to simulated laboratory weathering tests with fixed salt concentration (10% weight NaCl solution), at different temperatures, which were kept constant throughout each test (10, 20, 30, 40 oC). During each test, salt solutions flowed continuously imbibing samples by capilarity. Humidity within the simulation chamber was reduced using silica gel to keep it low and constant to increase evaporation rate. Temperature, humidity inside the simulation chamber and samples weight were digitally monitored during each test. Results show the advantages of the proposed experimental methodology using a continuous flow of salt solutions and shed light on the effect of temperature on the dynamics of salt crystallization on and within samples. Research funded by mission sector of high education ministry, Egypt and Geomateriales S2009/MAT-1629.

Analysis Thermal Comfort Condition in Complex Residential Building, Case Study: Chiangmai, Thailand

NASA Astrophysics Data System (ADS)

Juangjandee, Warangkana

2017-10-01

Due to the increasing need for complex residential buildings, it appears that people migrate into the high-density urban areas because the infrastructural facilities can be easily found in the modern metropolitan areas. Such rapid growth of urbanization creates congested residential buildings obstructing solar radiation and wind flow, whereas most urban residents spend 80-90% of their time indoor. Furthermore, the buildings were mostly built with average materials and construction detail. This causes high humidity condition for tenants that could promote mould growth. This study aims to analyse thermal comfort condition in complex residential building, Thailand for finding the passive solution to improve indoor air quality and respond to local conditions. The research methodology will be in two folds: 1) surveying on case study 2) analysis for finding the passive solution of reducing humidity indoor air The result of the survey indicated that the building need to find passive solution for solving humidity problem, that can be divided into two ways which raising ventilation and indoor temperature including increasing wind-flow ventilation and adjusting thermal temperature, for example; improving building design and stack driven ventilation. For raising indoor temperature or increasing mean radiant temperature, daylight can be passive solution for complex residential design for reducing humidity and enhance illumination indoor space simultaneous.

Aloe vera plant-extracted solution hydrothermal synthesis and magnetic properties of magnetite (Fe3O4) nanoparticles

NASA Astrophysics Data System (ADS)

Phumying, Santi; Labuayai, Sarawuth; Thomas, Chunpen; Amornkitbamrung, Vittaya; Swatsitang, Ekaphan; Maensiri, Santi

2013-06-01

Magnetite (Fe3O4) nanoparticles have been successfully synthesized by a novel hydrothermal method using ferric acetylacetonate (Fe(C5H8O2)3) and aloe vera plant-extracted solution. The influences of different reaction temperatures and times on the structure and magnetic properties of the synthesized Fe3O4 nanoparticles were investigated. The synthesized nanoparticles are crystalline and have particle sizes of ˜6-30 nm, as revealed by transmission electron microscopy (TEM). The results of X-ray diffraction (XRD), High resolution TEM (HRTEM) and selected area electron diffraction (SAED) indicate that the synthesized Fe3O4 nanoparticles have the inverse cubic spinel structure without the presence of any other phase impurities. The hysteresis loops of the Fe3O4 nanoparticles at room temperature show superparamagnetic behavior and the saturation magnetization of the Fe3O4 samples increases with increasing reaction temperature and time.

Specific physical and chemical properties of two modifications of poly(N-vinylcaprolcatam)

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

Chihacheva, I. P.; Timaeva, O. I.; Kuz’micheva, G. M., E-mail: galina-kuzmicheva@list.ru

2016-05-15

Two modifications of poly(N-vinylcaprolactam)—PVCL25 and PVCL40 (drying of a PVCL solution at 25 and 40°C, respectively)—as powdered films and their solutions were systematically investigated for the first time. Powders were studied by X-ray diffraction, IR spectroscopy, scanning electron microscopy, low-temperature krypton adsorption, and differential scanning calorimetry. Solutions were studied by smallangle X-ray scattering and dynamic light scattering. It was demonstrated that powders of PVCL25 and PVCL40 differ in the characteristics of the sub- and microstructure and in the water content and the solutions differ in the particle size. The relationships between the characteristics of the systems in the solid andmore » liquid state and between the hydrodynamic diameter of PVCL particles in solution and their coagulation time were found.« less

Temperature and Humidity Calibration of a Low-Cost Wireless Dust Sensor for Real-Time Monitoring.

PubMed

Hojaiji, Hannaneh; Kalantarian, Haik; Bui, Alex A T; King, Christine E; Sarrafzadeh, Majid

2017-03-01

This paper introduces the design, calibration, and validation of a low-cost portable sensor for the real-time measurement of dust particles within the environment. The proposed design consists of low hardware cost and calibration based on temperature and humidity sensing to achieve accurate processing of airborne dust density. Using commercial particulate matter sensors, a highly accurate air quality monitoring sensor was designed and calibrated using real world variations in humidity and temperature for indoor and outdoor applications. Furthermore, to provide a low-cost secure solution for real-time data transfer and monitoring, an onboard Bluetooth module with AES data encryption protocol was implemented. The wireless sensor was tested against a Dylos DC1100 Pro Air Quality Monitor, as well as an Alphasense OPC-N2 optical air quality monitoring sensor for accuracy. The sensor was also tested for reliability by comparing the sensor to an exact copy of itself under indoor and outdoor conditions. It was found that accurate measurements under real-world humid and temperature varying and dynamically changing conditions were achievable using the proposed sensor when compared to the commercially available sensors. In addition to accurate and reliable sensing, this sensor was designed to be wearable and perform real-time data collection and transmission, making it easy to collect and analyze data for air quality monitoring and real-time feedback in remote health monitoring applications. Thus, the proposed device achieves high quality measurements at lower-cost solutions than commercially available wireless sensors for air quality.

HST3D; a computer code for simulation of heat and solute transport in three-dimensional ground-water flow systems

USGS Publications Warehouse

Kipp, K.L.

1987-01-01

The Heat- and Soil-Transport Program (HST3D) simulates groundwater flow and associated heat and solute transport in three dimensions. The three governing equations are coupled through the interstitial pore velocity, the dependence of the fluid density on pressure, temperature, the solute-mass fraction , and the dependence of the fluid viscosity on temperature and solute-mass fraction. The solute transport equation is for only a single, solute species with possible linear equilibrium sorption and linear decay. Finite difference techniques are used to discretize the governing equations using a point-distributed grid. The flow-, heat- and solute-transport equations are solved , in turn, after a particle Gauss-reduction scheme is used to modify them. The modified equations are more tightly coupled and have better stability for the numerical solutions. The basic source-sink term represents wells. A complex well flow model may be used to simulate specified flow rate and pressure conditions at the land surface or within the aquifer, with or without pressure and flow rate constraints. Boundary condition types offered include specified value, specified flux, leakage, heat conduction, and approximate free surface, and two types of aquifer influence functions. All boundary conditions can be functions of time. Two techniques are available for solution of the finite difference matrix equations. One technique is a direct-elimination solver, using equations reordered by alternating diagonal planes. The other technique is an iterative solver, using two-line successive over-relaxation. A restart option is available for storing intermediate results and restarting the simulation at an intermediate time with modified boundary conditions. This feature also can be used as protection against computer system failure. Data input and output may be in metric (SI) units or inch-pound units. Output may include tables of dependent variables and parameters, zoned-contour maps, and plots of the dependent variables versus time. (Lantz-PTT)

One-step synthesis of mesoporous pentasil zeolite with single-unit-cell lamellar structural features

DOEpatents

Tsapstsis, Michael; Zhang, Xueyi

2015-11-17

A method for making a pentasil zeolite material includes forming an aqueous solution that includes a structure directing agent and a silica precursor; and heating the solution at a sufficient temperature and for sufficient time to form a pentasil zeolite material from the silica precursor, wherein the structure directing agent includes a quaternary phosphonium ion.

On the use temperature parameterized rate coefficients in the estimation of non-equilibrium reaction rates

NASA Astrophysics Data System (ADS)

Shizgal, Bernie D.; Chikhaoui, Aziz

2006-06-01

The present paper considers a detailed analysis of the nonequilibrium effects for a model reactive system with the Chapman-Eskog (CE) solution of the Boltzmann equation as well as an explicit time dependent solution. The elastic cross sections employed are a hard sphere cross section and the Maxwell molecule cross section. Reactive cross sections which model reactions with and without activation energy are used. A detailed comparison is carried out with these solutions of the Boltzmann equation and the approximation introduced by Cukrowski and coworkers [J. Chem. Phys. 97 (1992) 9086; Chem. Phys. 89 (1992) 159; Physica A 188 (1992) 344; Chem. Phys. Lett. A 297 (1998) 402; Physica A 275 (2000) 134; Chem. Phys. Lett. 341 (2001) 585; Acta Phys. Polonica B 334 (2003) 3607.] based on the temperature of the reactive particles. We show that the Cukrowski approximation has limited applicability for the large class of reactive systems studied in this paper. The explicit time dependent solutions of the Boltzmann equation demonstrate that the CE approach is valid only for very slow reactions for which the corrections to the equilibrium rate coefficient are very small.

Observations on dedolomitization of carbonate concrete aggregates, implications for ACR and expansion

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

Prinčič, Tina, E-mail: Tina.Princic@uni-lj.si; Štukovnik, Petra; Pejovnik, Stane

2013-12-15

Some carbonate aggregates used in concrete are unstable in a high alkaline solution, which is present also in pore solution of cement binder. This paper investigates the process of dedolomitization of carbonate aggregate rocks and mortar bars. Selected aggregates, limestone and dolostone are of high purity without reactive silica involvement confirmed by the XRD and the XRF. For the process of dedolomitization the effect of various temperatures, solutions and time was examined. In this investigation, measurements of expansion, optical and scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction were used. Te results indicate that the process ofmore » dedolomitization occurred not only in the NaOH solution but also in the water on the mortar bar with virgin dolostone aggregate. Elevated temperature, 60 °C, increased the rate of reaction. Furthermore, the rate of reaction significantly correlates with time, which has also been confirmed through the Rietveld analysis. -- Highlights: •The dedolomitization caused no expansion. •It occurs in the dolostone aggregate without reactive silica involvement. •It has taken place already with the presence of the cement binder. •A significant alteration occurred: formation of rims, new pores and phases.« less

Nonlinear dynamics of mushy layers induced by external stochastic fluctuations.

PubMed

Alexandrov, Dmitri V; Bashkirtseva, Irina A; Ryashko, Lev B

2018-02-28

The time-dependent process of directional crystallization in the presence of a mushy layer is considered with allowance for arbitrary fluctuations in the atmospheric temperature and friction velocity. A nonlinear set of mushy layer equations and boundary conditions is solved analytically when the heat and mass fluxes at the boundary between the mushy layer and liquid phase are induced by turbulent motion in the liquid and, as a result, have the corresponding convective form. Namely, the 'solid phase-mushy layer' and 'mushy layer-liquid phase' phase transition boundaries as well as the solid fraction, temperature and concentration (salinity) distributions are found. If the atmospheric temperature and friction velocity are constant, the analytical solution takes a parametric form. In the more common case when they represent arbitrary functions of time, the analytical solution is given by means of the standard Cauchy problem. The deterministic and stochastic behaviour of the phase transition process is analysed on the basis of the obtained analytical solutions. In the case of stochastic fluctuations in the atmospheric temperature and friction velocity, the phase transition interfaces (mushy layer boundaries) move faster than in the deterministic case. A cumulative effect of these noise contributions is revealed as well. In other words, when the atmospheric temperature and friction velocity fluctuate simultaneously due to the influence of different external processes and phenomena, the phase transition boundaries move even faster. This article is part of the theme issue 'From atomistic interfaces to dendritic patterns'.This article is part of the theme issue 'From atomistic interfaces to dendritic patterns'. © 2018 The Author(s).

A Novel Nanocomposite as an Efficient Adsorbent for the Rapid Adsorption of Ni(II) from Aqueous Solution

PubMed Central

Wang, Ximing; Chen, Zhangjing

2017-01-01

A sulfhydryl-lignocellulose/montmorillonite (SLT) nanocomposite was prepared using a chemical intercalation reaction. The SLT nanocomposite was characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Transmission Electron Microscopy (TEM), the results demonstrated that an intercalated-exfoliated nanostructure was formed in the SLT nanocomposite. Batch experiments were conducted to optimize parameters such as SLT nanocomposite dosage, the initial concentration of Ni(II), solution pH, temperature, and time. The results indicated that the attractive adsorption capacity reached 1134.08 mg/g with 0.05 g of SLT at an initial concentration of Ni(II) of 700 mg/L, solution pH of 5.5, adsorption temperature of 50 °C, and adsorption time of 40 min, meanwhile, the Ni(II) adsorption capacity significantly decreased with the increase in ionic strength. The pseudo-second order kinetic model could describe the whole adsorption process well, and the isotherm adsorption equilibrium conformed to the Freundlich model. The adsorption mechanism of SLT was also discussed by means of FTIR and Energy-Dispersive X-Ray (EDX). Dramatically, the introduction of sulfhydryl achieves the increased activated functional groups content of SLT nanocomposite, leading to remarkably higher adsorption amount on Ni(II). The desorption capacity of SLT was dependent on parameters such as HNO3 concentration, desorption temperature, and ultrasonic desorption time. The satisfactory desorption capacity and desorption efficiency of 458.21 mg/g and 40.40% were obtained at an HNO3 concentration, desorption temperature, and ultrasonic desorption time of 0.4 mol/L, 40 °C, and 30 min, respectively. The regeneration studies showed that the adsorption capacity of SLT was consistent for four cycles without any appreciable loss and confirmed that the SLT was reusable. Owing to such outstanding features, the novel SLT nanocomposite proved the great potential in adsorption for Ni(II) removal from aqueous solution, and exhibited an extremely significant amount of Ni(II), compared to pristine lignocellulose/montmorillonite and the conventional spent adsorbents. PMID:28937606

Factors contributing to inactivation of isolated thylakoid membranes during freezing in the presence of variable amounts of glucose and NaCl.

PubMed Central

Santarius, K A; Giersch, C

1984-01-01

During freezing of isolated spinach thylakoids in sugar/salt solutions, the two solutes affected membrane survival in opposite ways: membrane damage due to increased electrolyte concentration can be prevented by sugar. Calculation of the final concentrations of NaCl or glucose reached in the residual unfrozen portion of the system revealed that the effects of the solutes on membrane activity can be explained in part by colligative action. In addition, the fraction of the residual liquid in the frozen system contributes to membrane injury. During severe freezing in the presence of very low initial solute concentrations, membrane damage drastically increased with a decrease in the volume of the unfrozen solution. Freezing injury under these conditions is likely to be due to mechanical damage by the ice crystals that occupy a very high fraction of the frozen system. At higher starting concentrations of sugar plus salt, membrane damage increased with an increase in the amount of the residual unfrozen liquid. Thylakoid inactivation at these higher initial solute concentrations can be largely attributed to dilution of the membrane fraction, as freezing damage at a given sugar/salt ratio decreased with increasing the thylakoid concentration in the sample. Moreover, membrane survival in the absence of freezing decreased with lowering the temperature, indicating that the temperature affected membrane damage not only via alterations related to the ice formation. From the data it was evident that damage of thylakoid membranes was determined by various individual factors, such as the amount of ice formed, the final concentrations of solutes and membranes in the residual unfrozen solution, the final volume of this fraction, the temperature and the freezing time. The relative contribution of these factors depended on the experimental conditions, mainly the sugar/salt ratio, the initial solute concentrations, and the freezing temperature. PMID:6478028

Dielectric spectroscopy in aqueous solutions of paracetamol over the frequency range of 20 Hz to 2 MHz at 293.15 K temperature

NASA Astrophysics Data System (ADS)

Pandit, T. R.; Rana, V. A.

2018-05-01

Frequency domain dielectric relaxation spectroscopy plays an important role in the study of pharmaceutical drug molecules. The complex relative dielectric permittivity ɛ*(ω) = ɛ' - j ɛ" of aqueous solutions of paracetamol in the frequency range of 20 Hz to 2 MHz at a temperature range of 293.15 K are measured with the help of Agilent precision LCR meter E4980A along with four terminal liquid test fixture Agilent 16452A. Data of complex relative permittivity are used to calculate loss tangent for all concentrations of paracetamol in distilled water. Electrode polarization relaxation time has been calculated for all solutions. Effect of variation of concentrations of paracetamol in distilled water on these dielectric parameters is discussed.

Crossing the phantom divide with dissipative normal matter in the Israel-Stewart formalism

NASA Astrophysics Data System (ADS)

Cruz, Norman; Lepe, Samuel

2017-04-01

A phantom solution in the framework of the causal Israel-Stewart (IS) formalism is discussed. We assume a late time behavior of the cosmic evolution by considering only one dominant matter fluid with viscosity. In the model it is assumed a bulk viscosity of the form ξ =ξ0ρ 1 / 2, where ρ is the energy density of the fluid. We evaluate and discuss the behavior of the thermodynamical parameters associated to this solution, like the temperature, rate of entropy, entropy, relaxation time, effective pressure and effective EoS. A discussion about the assumption of near equilibrium of the formalism and the accelerated expansion of the solution is presented. The solution allows to cross the phantom divide without evoking an exotic matter fluid and the effective EoS parameter is always lesser than -1 and time independent. A future singularity (big rip) occurs, but different from the Type I (big rip) solution classified in S. Nojiri, S.D. Odintsov and S. Tsujikawa (2005) [2], if we consider other thermodynamics parameters like, for example, the effective pressure in the presence of viscosity or the relaxation time.

Quantification of Marangoni flows and film morphology during solid film formation by inkjet printing

NASA Astrophysics Data System (ADS)

Ishizuka, Hirotaka; Fukai, Jun

2018-01-01

We visualized experimentally the internal flow inside inkjet droplets of polystyrene-anisole solution during solid film formation on substrates at room temperature. The effects of contact angle and evaporation rate on the internal flow and film morphology were quantitatively investigated. The transport process during film formation was examined by measuring the relationship between internal flow and film morphology, which provided three remarkable findings. First, self-pinning and the strength of outward flow on the free surface under 2.3 Pa s determined film morphology. The solute distribution, corresponding to rim areas in ring-like films and a convex trough in dot-like films, had already developed at self-pinning. Second, the mass fraction at self-pinning close to the contact line converged to one, regardless of the film morphology. This implies that self-pinning is independent of parameters such as the contact angle and evaporation rate. Third, at room temperature, the solutal Marangoni numbers were 20-30 times larger than the thermal ones. Thus, the outward flow on the free surface caused by the solutal Marangoni effect dominates in droplets before self-pinning. The solutal Marangoni number at self-pinning and thickness variation at the center of the film displayed a good relationship for droplets with different contact angles and evaporation rates. This suggests that film morphology can be technically controlled by solutal Marangoni number at room temperature.

Thermally stable booster explosive and process for manufacture

DOEpatents

Quinlin, William T [Amarillo, TX; Thorpe, Raymond [Amarillo, TX; Lightfoot, James M [Amarillo, TX

2006-03-21

A thermally stable booster explosive and process for the manufacture of the explosive. The product explosive is 2,4,7,9-tetranitro-10H-benzo[4,5]furo[3,2-b]indole (TNBFI). A reactant/solvent such as n-methylpyrrolidone (NMP) or dimethyl formamide (DMF) is made slightly basic. The solution is heated to reduce the water content. The solution is cooled and hexanitrostilbene is added. The solution is heated to a predetermined temperature for a specific time period, cooled, and the product is collected by filtration.

Effect of thermal exposure on mechanical properties hypo eutectic aerospace grade aluminium-silicon alloy

NASA Astrophysics Data System (ADS)

Nagesh Kumar, R.; Ram Prabhu, T.; Siddaraju, C.

2016-09-01

The effect of thermal exposure on the mechanical properties of a C355.0 aerospace grade aluminum-silicon alloy (5% Si - 1.2% Cu - 0.5% Mg) was investigated in the present study. The alloy specimens were subjected to T6 (solution treatment and artificial ageing treatment) temper treatment to enhance the strength properties through precipitation hardening. The T6 temper treatment involved solution heat treatment at 520oC for 6h, followed by water quenching and ageing at 150oC. After the heat treatment, the specimens were exposed to various temperatures (50oC, 100oC, 150oC, 200oC and 250oC) for 5 and 10 h to study the structural applications of this alloy to the various Mach number military aircrafts. After the thermal exposure, specimens were tested for tensile, hardness and impact properties (Charpy). The microstructure of the thermal exposed specimens was examined in the optical microscopes and correlated with the mechanical properties results. In summary, an increase of exposure time has a different effect on the tensile and hardness properties of the alloy. For the exposure time 5h, the tensile and hardness properties increase upto 100oC and later decrease with an increase of temperature. In contrast, the tensile and hardness properties linearly decrease with an increase of temperature. Several factors such as matrix grain growth, diffusion rate, Si particles size and distribution, precipitate stability play a key role on deciding the tensile properties of the alloy. Comparing the relative effects of temperature and time, the temperature effects dominate more in deteriorating tensile properties of the alloy. There are no effects of exposure temperature and/or time on the impact properties of the alloy.

Through-vial impedance spectroscopy of the mechanisms of annealing in the freeze-drying of maltodextrin: the impact of annealing hold time and temperature on the primary drying rate.

PubMed

Smith, Geoff; Arshad, Muhammad Sohail; Polygalov, Eugene; Ermolina, Irina

2014-06-01

The study aims to investigate the impact of annealing hold time and temperature on the primary drying rate/duration of a 10% (w/v) solution of maltodextrin with an emphasis on how the mechanisms of annealing might be understood from the in-vial measurements of the ice crystal growth and the glass transition. The electrical impedance of the solution within a modified glass vial was recorded between 10 and 10(6) Hz during freeze-drying cycles with varying annealing hold times (1-5 h) and temperatures. Primary drying times decreased by 7%, 27% and 34% (1.1, 4.3 and 5.5 h) with the inclusion of an annealing step at temperatures of -15°C, -10°C and -5°C, respectively. The glass transition was recorded at approximately -16°C during the re-heating and re-cooling steps, which is close to the glass transition (Tg ') reported for 10% (w/v) maltodextrin and therefore indicates that a maximum freeze concentration (∼86%, w/w, from the Gordon-Taylor equation) was achieved during first freezing, with no further ice being formed on annealing. This observation, coupled to the decrease in electrical resistance that was observed during the annealing hold time, suggests that the reduction in the drying time was because of improved connectivity of ice crystals because of Ostwald ripening rather than devitrification. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

Temperature dependence of protein solubility-determination, application to crystallization, and growth kinetics studies

NASA Technical Reports Server (NTRS)

Rosenberger, Franz

1993-01-01

A scintillation method was developed for determinations of the temperature dependence of the solubility, and of nucleation induction times of proteins, in 50-100 mu(l) volumes of solution. Solubility data for lysozyme and horse serum albumin were obtained for various combinations of pH and precipitant concentrations. These data and the nucleation induction information were used for dynamic crystallization control, that is, for the controlled separation of nucleation and growth stages. Individual lysozyme and horse serum albumin crystals were grown in 15-20 mu(l) solution volumes contained in x-ray capillaries. The morphology and kinetics of the growth and dissolution of lysozyme in aqueous solutions with 2.5 percent NaCl and at pH = 4.5 was studied in situ with a depth resolution of 300 A (4 unit cells) by high resolution optical microscopy and digital image processing. The bulk super- or under saturation, sigma, of the solution inside a closed growth cell was controlled by temperature. The growth habit was bound by (110) and (101) faces that grew through layer spreading, although with different growth rate dependencies on supersaturation/temperature. At sigma less than 10 (obtained at higher temperatures) growth was purely kinetic ally controlled, with impurity effects (macrostep formation and kinetic hindrance) becoming significant for sigma less than 2. At sigma greater than 10 (lower temperatures), anisotropies in the interfacial kinetics were more pronounced, with interfacial kinetics and bulk transport becoming equally important to the growth morphology. Growth rates were growth history dependent. The formation of striations (layers of irregularly incorporated solution) was unambiguously correlated with growth temperature variations. Etching exposed dislocations and various high-index faces whose growth morphologies were studied during return to the steady state growth form. Growth steps were observed to originate from two-dimensional nuclei or from outcrops of growth striations, and from dislocations that preferentially formed in growth sector boundaries.

Fast synthesize ZnO quantum dots via ultrasonic method.

PubMed

Yang, Weimin; Zhang, Bing; Ding, Nan; Ding, Wenhao; Wang, Lixi; Yu, Mingxun; Zhang, Qitu

2016-05-01

Green emission ZnO quantum dots were synthesized by an ultrasonic sol-gel method. The ZnO quantum dots were synthesized in various ultrasonic temperature and time. Photoluminescence properties of these ZnO quantum dots were measured. Time-resolved photoluminescence decay spectra were also taken to discover the change of defects amount during the reaction. Both ultrasonic temperature and time could affect the type and amount of defects in ZnO quantum dots. Total defects of ZnO quantum dots decreased with the increasing of ultrasonic temperature and time. The dangling bonds defects disappeared faster than the optical defects. Types of optical defects first changed from oxygen interstitial defects to oxygen vacancy and zinc interstitial defects. Then transformed back to oxygen interstitial defects again. The sizes of ZnO quantum dots would be controlled by both ultrasonic temperature and time as well. That is, with the increasing of ultrasonic temperature and time, the sizes of ZnO quantum dots first decreased then increased. Moreover, concentrated raw materials solution brought larger sizes and more optical defects of ZnO quantum dots. Copyright © 2015 Elsevier B.V. All rights reserved.

Chemical Corrosion of Liquid-Phase Sintered SiC in Acidic/Alkaline Solutions Part 1. Corrosion in HNO3 Solution

NASA Astrophysics Data System (ADS)

Zhang, Lei; Zhang, Ming; He, Xinnong; Tang, Wenming

2016-03-01

The corrosion behavior of the liquid-phase sintered SiC (LPS-SiC) was studied by dipping in 3.53 mol/L HNO3 aqueous solution at room temperature and 70 °C, respectively. The weight loss, strength reduction and morphology evolution of the SiC specimens during corroding were revealed and also the chemical corrosion process and mechanism of the SiC specimens in the acidic solution were clarified. The results show that the corrosion of the LPS-SiC specimens in the HNO3 solution is selective. The SiC particles are almost free from corrosion, but the secondary phases of BaAl2Si2O8 (BAS) and Y2Si2O7 are corroded via an acid-alkali neutralization reaction. BAS has a higher corrosion rate than Y2Si2O7, resulting in the formation of the bamboo-leaf-like corrosion pits. As the SiC specimens etched in the HNO3 solution at room temperature for 75 days, about 80 μm thickness corrosion layer forms. The weight loss and bending strength reduction of the etched SiC specimens are 2.6 mg/cm2 and 52%, respectively. The corrosion of the SiC specimens is accelerated in the 70 °C HNO3 solution with a rate about five times bigger than that in the same corrosion medium at room temperature.

Time dependent shear stress and temperature distribution over an insulated flat plate moving at hypersonic speed.

NASA Technical Reports Server (NTRS)

Rodkiewicz, C. M.; Gupta, R. N.

1971-01-01

The laminar two-dimensional flow over a stepwise accelerated flat plate moving with hypersonic speed at zero angle of attack is analysed. The governing equations in the self-similar form are linearized and solved numerically for small times. The solutions obtained are the deviations of the velocity and the temperature profiles from those of steady state. The presented results may be used to find the first order boundary layer induced pressure on the plate.

Effect of salt solutions on radiosensitivity of mammalian cells. I. Specific ion effects.

PubMed

Raaphorst, G P; Kruuv, J

1977-07-01

The radiation isodose survival curve of cells subjected to a wide concentration range of sucrose solutions has two maxima separated by a minimum. Both cations and anions can alter the cellular radiosensitivity above and beyond the osmotic effect observed for cells treated with sucrose solutions. The basic shape of the isodose curve can also be modulated by changes in temperature and solution exposure times. Some of these alterations in radiosensitivity may be related to changes in the amount and structure of cellular water or macromolecular conformation or to the direct effect of the ions, expecially at high solute concentrations.

A solution-processed quaternary oxide system obtained at low-temperature using a vertical diffusion technique

PubMed Central

Yoon, Seokhyun; Kim, Si Joon; Tak, Young Jun; Kim, Hyun Jae

2017-01-01

We report a method for fabricating solution-processed quaternary In-Ga-Zn-O (IGZO) thin-film transistors (TFTs) at low annealing temperatures using a vertical diffusion technique (VDT). The VDT is a deposition process for spin-coating binary and ternary oxide layers consecutively and annealing at once. With the VDT, uniform and dense quaternary oxide layers were fabricated at lower temperatures (280 °C). Compared to conventional IGZO and ternary In-Zn-O (IZO) thin films, VDT IGZO thin film had higher density of the metal-oxide bonds and lower density of the oxygen vacancies. The field-effect mobility of VDT IGZO TFT increased three times with an improved stability under positive bias stress than IZO TFT due to the reduction in oxygen vacancies. Therefore, the VDT process is a simple method that reduces the processing temperature without any additional treatment for quaternary oxide semiconductors with uniform layers. PMID:28230088

A solution-processed quaternary oxide system obtained at low-temperature using a vertical diffusion technique

NASA Astrophysics Data System (ADS)

Yoon, Seokhyun; Kim, Si Joon; Tak, Young Jun; Kim, Hyun Jae

2017-02-01

We report a method for fabricating solution-processed quaternary In-Ga-Zn-O (IGZO) thin-film transistors (TFTs) at low annealing temperatures using a vertical diffusion technique (VDT). The VDT is a deposition process for spin-coating binary and ternary oxide layers consecutively and annealing at once. With the VDT, uniform and dense quaternary oxide layers were fabricated at lower temperatures (280 °C). Compared to conventional IGZO and ternary In-Zn-O (IZO) thin films, VDT IGZO thin film had higher density of the metal-oxide bonds and lower density of the oxygen vacancies. The field-effect mobility of VDT IGZO TFT increased three times with an improved stability under positive bias stress than IZO TFT due to the reduction in oxygen vacancies. Therefore, the VDT process is a simple method that reduces the processing temperature without any additional treatment for quaternary oxide semiconductors with uniform layers.

Analysis and Sizing for Transient Thermal Heating of Insulated Aerospace Vehicle Structures

NASA Technical Reports Server (NTRS)

Blosser, Max L.

2012-01-01

An analytical solution was derived for the transient response of an insulated structure subjected to a simplified heat pulse. The solution is solely a function of two nondimensional parameters. Simpler functions of these two parameters were developed to approximate the maximum structural temperature over a wide range of parameter values. Techniques were developed to choose constant, effective thermal properties to represent the relevant temperature and pressure-dependent properties for the insulator and structure. A technique was also developed to map a time-varying surface temperature history to an equivalent square heat pulse. Equations were also developed for the minimum mass required to maintain the inner, unheated surface below a specified temperature. In the course of the derivation, two figures of merit were identified. Required insulation masses calculated using the approximate equation were shown to typically agree with finite element results within 10%-20% over the relevant range of parameters studied.

A solution-processed quaternary oxide system obtained at low-temperature using a vertical diffusion technique.

PubMed

Yoon, Seokhyun; Kim, Si Joon; Tak, Young Jun; Kim, Hyun Jae

2017-02-23

We report a method for fabricating solution-processed quaternary In-Ga-Zn-O (IGZO) thin-film transistors (TFTs) at low annealing temperatures using a vertical diffusion technique (VDT). The VDT is a deposition process for spin-coating binary and ternary oxide layers consecutively and annealing at once. With the VDT, uniform and dense quaternary oxide layers were fabricated at lower temperatures (280 °C). Compared to conventional IGZO and ternary In-Zn-O (IZO) thin films, VDT IGZO thin film had higher density of the metal-oxide bonds and lower density of the oxygen vacancies. The field-effect mobility of VDT IGZO TFT increased three times with an improved stability under positive bias stress than IZO TFT due to the reduction in oxygen vacancies. Therefore, the VDT process is a simple method that reduces the processing temperature without any additional treatment for quaternary oxide semiconductors with uniform layers.

Effect of peritoneal lavage solution temperature on body temperature in anaesthetised cats and small dogs.

PubMed

Barnes, D C; Leece, E A; Trimble, T A; Demetriou, J L

2017-05-20

A prospective, randomised, non-blinded, clinical study to assess the effect of peritoneal lavage using warmed fluid on body temperature in anesthetised cats and dogs of less than 10 kg body mass undergoing coeliotomy. A standardised anaesthetic protocol was used. Oesophageal and rectal temperatures were measured at various time points. At the end of surgery, group 1 patients (n=10) were lavaged with 200 ml/kg sterile isotonic saline at 34±1°C and group 2 (n=10) at 40±1°C. Groups were similar with respect to age, mass, body condition and surgical incision length. Duration of anaesthesia, surgical procedures and peritoneal lavage was similar between groups. Linear regression showed no significant change in oesophageal temperature during the lavage period for group 1 (P=0.64), but a significant increase for group 2 patients (P<0.0001), with mean temperature changes of -0.5°C (from (36.3°C to 35.9°C) and +0.9°C (from 35.4°C to 36.3°C), respectively. Similar results were found for rectal temperature, with mean changes of -0.5°C and +0.8°C (P=0.922 and 0.045), respectively. The use of isotonic crystalloid solution for peritoneal lavage at a temperature of 40±1°C significantly warms small animal patients, when applied in a clinical setting, compared with lavage solution at 34±1°C. British Veterinary Association.

Effect of clathrate hydrate formation and decomposition on NMR parameters in THF-D2O solution.

PubMed

Rousina-Webb, Alexander; Leek, Donald M; Ripmeester, John

2012-06-28

The NMR spin-lattice relaxation time (T(1)), spin-spin relaxation time (T(2)) and the diffusion coefficient D were measured for (1)H in a 1:17 mol % solution of tetrahydrofuran (THF) in D(2)O. The aim of the work was to clarify some earlier points raised regarding the utility of these measurements to convey structural information on hydrate formation and reformation. A number of irregularities in T(1) and T(2) measurements during hydrate processes reported earlier are explained in terms of the presence of interfaces and possible temperature gradients. We observe that T(1) and T(2) in solution are exactly the same before and after hydrate formation, thus confirming that the solution is isotropic. This is inconsistent with the presence of memory effects, at least those that may affect the dynamics to which T(1) and T(2) are sensitive. The measurement of the diffusion coefficient for a number of hours in the subcooled solution before nucleation proved invariant with time, again suggesting that the solution remains isotropic without affecting the guest dynamics and diffusion.

Nanoflare vs Footpoint Heating : Observational Signatures

NASA Technical Reports Server (NTRS)

Winebarger, Amy; Alexander, Caroline; Lionello, Roberto; Linker, Jon; Mikic, Zoran; Downs, Cooper

2015-01-01

Time lag analysis shows very long time lags between all channel pairs. Impulsive heating cannot address these long time lags. 3D Simulations of footpoint heating shows a similar pattern of time lags (magnitude and distribution) to observations. Time lags and relative peak intensities may be able to differentiate between TNE and impulsive heating solutions. Adding a high temperature channel (like XRT Be-­thin) may improve diagnostics.

Batch and continuous (fixed-bed column) biosorption of crystal violet by Artocarpus heterophyllus (jackfruit) leaf powder.

PubMed

Saha, Papita Das; Chakraborty, Sagnik; Chowdhury, Shamik

2012-04-01

In this study, batch and fixed-bed column experiments were performed to investigate the biosorption potential of Artocarpus heterophyllus (jackfruit) leaf powder (JLP) to remove crystal violet (CV) from aqueous solutions. Batch biosorption studies were carried out as a function of solution pH, contact time, initial dye concentration and temperature. The biosorption equilibrium data showed excellent fit to the Langmuir isotherm model with maximum monolayer biosorption capacity of 43.39 mg g(-1) at pH 7.0, initial dye concentration=50 mg L(-1), temperature=293 K and contact time=120 min. According to Dubinin-Radushkevich (D-R) isotherm model, biosorption of CV by JLP was chemisorption. The biosorption kinetics followed the pseudo-second-order kinetic model. Thermodynamic analysis revealed that biosorption of CV from aqueous solution by JLP was a spontaneous and exothermic process. In order to ascertain the practical applicability of the biosorbent, fixed-bed column studies were also performed. The breakthrough time increased with increasing bed height and decreased with increasing flow rate. The Thomas model as well as the BDST model showed good agreement with the experimental results at all the process parameters studied. It can be concluded that JLP is a promising biosorbent for removal of CV from aqueous solutions. Copyright © 2011 Elsevier B.V. All rights reserved.

Characterization of a New Phase and Its Effect on the Work Characteristics of a Near-Stoichiometric Ni30Pt20Ti50 High-Temperature Shape Memory Alloy (HTSMA)

NASA Technical Reports Server (NTRS)

Garg, A.; Gaydosh, D.; Noebe, R.D.; Padula II, Santo; Bigelow, G.S.; Kaufman, M.; Kovarik, L.; Mills, M.J.; Diercks, D.; McMurray, S.

2008-01-01

A new phase observed in a nominal Ni30Pt20Ti50 (at.%) high temperature shape memory alloy has been characterized using transmission electron microscopy and 3-D atom probe tomography. This phase forms homogeneously in the B2 austenite matrix by a nucleation and growth mechanism and results in a concomitant increase in the martensitic transformation temperature of the base alloy. Although the structure of this phase typically contains a high density of faults making characterization difficult, it appears to be trigonal (-3m point group) with a(sub o) approx. 1.28 nm and c(sub o) approx. 1.4 nm. Precipitation of this phase increases the microhardness of the alloy substantially over that of the solution treated and quenched single-phase material. The effect of precipitation strengthening on the work characteristics of the alloy has been explored through load-biased strain-temperature testing in the solution-treated condition and after aging at 500 C for times ranging from 1 to 256 hours. Work output was found to increase in the aged alloy as a result of an increase in transformation strain, but was not very sensitive to aging time. The amount of permanent deformation that occurred during thermal cycling under load was small but increased with increasing aging time and stress. Nevertheless, the dimensional stability of the alloy at short aging times (1-4 hours) was still very good making it a potentially useful material for high-temperature actuator applications.

Formulation and synthesis of hydrogels having lower critical solution temperature near body temperature

NASA Astrophysics Data System (ADS)

Abidin, A. Z.; Graha, H. P. R.; Trirahayu, D. A.

2017-07-01

Copolymerization between bacterial cellulose nanocrystal (CN) and methyl cellulose (MC) was carried out using UV light to produce a biocompatible hydrogel at body temperature and liquid at room temperature. Viscosity and salt effect of the MC and copolymer solution at room temperature and its Lower Critical Solution Temperature (LCST) were evaluated. The analysis showed that the higher concentration of methyl cellulose and salt content in the solution produced lower LCST and higher solution viscosity. All samples of polymer solution with MC concentrations of 1 and 2% have a viscosity less than 5000 cP at room temperature. The solutions with MC concentration of 1, 2, and 3% have respectively LCST of 59, 58, and 57°C, while its copolymer solutions with CN concentration of 0.1, 0.3, and 0.5% have respectively LCST of 55, 51, and 41°C. The salt addition to the solution of MC-CN copolymer with concentrations of 1x and 1.5x Phosphat Buffered Saline (PBS) produces respectively LCST of 47 and 38°C. The results suggest that the copolymer solution of MC-CN could produce a lower LCST and the addition of salt could amplify the effect of LCST decrease that can be used to produce a biocompatible hydrogel with LCST as close as body temperature.

Temperature affects transport of polysaccharides and proteins in articular cartilage explants.

PubMed

Moeini, Mohammad; Lee, Kwan-Bong; Quinn, Thomas M

2012-07-26

Solute transport phenomena mediate many aspects of the physiology and contrast agent-based clinical imaging of articular cartilage. Temperatures up to 10°C below standard body temperature (37°C) are common in articulating joints during normal activities and clinically (e.g. cold treatment of injuries). Therefore it is of interest to characterize the effects of temperature changes on solute transport parameters in cartilage. A range of fluorescent solutes including fluorescein isothiocyanate, 4 and 40kDa dextrans, myoglobin, insulin and chondroitin sulfate were prepared and used in assays of solute effective partition coefficient and effective diffusivity in bovine intermediate zone articular cartilage explants maintained at 10, 22 or 37°C. Trends for increasing partition coefficient with increasing temperature were evident for all solutes except chondroitin sulfate, with significant changes between 22 and 37°C for 4kDa dextran, insulin and myoglobin. Diffusivities of most solutes tested also tended to increase with increasing temperature, with significant changes between 10 and 22°C for FITC, 40kDa dextran and myoglobin. Oddly, insulin diffusivity decreased significantly as temperature increased from 22 to 37°C while chondroitin sulfate diffusivity exhibited no clear temperature dependence. These results highlight solute-specific temperature dependences of transport phenomena which may depend upon molecular weight, chemical structure, molecular conformation, and solute-matrix and solute-solute interactions. The articular cartilage explants themselves exhibited small but significant changes in water and glycosaminoglycan contents during experiments, underscoring the importance of solute-matrix interactions. Solute transport parameters in cartilage and their temperature dependences are therefore not easily predicted, and case-by-case experimental determination may be essential. Copyright © 2012 Elsevier Ltd. All rights reserved.

Martensitic/ferritic steels as container materials for liquid mercury target of ESS

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

Dai, Y.

1996-06-01

In the previous report, the suitability of steels as the ESS liquid mercury target container material was discussed on the basis of the existing database on conventional austenitic and martensitic/ferritic steels, especially on their representatives, solution annealed 316 stainless steel (SA 316) and Sandvik HT-9 martensitic steel (HT-9). Compared to solution annealed austenitic stainless steels, martensitic/ferritic steels have superior properties in terms of strength, thermal conductivity, thermal expansion, mercury corrosion resistance, void swelling and irradiation creep resistance. The main limitation for conventional martensitic/ferritic steels (CMFS) is embrittlement after low temperature ({le}380{degrees}C) irradiation. The ductile-brittle transition temperature (DBTT) can increase asmore » much as 250 to 300{degrees}C and the upper-shelf energy (USE), at the same time, reduce more than 50%. This makes the application temperature range of CMFS is likely between 300{degrees}C to 500{degrees}C. For the present target design concept, the temperature at the container will be likely controlled in a temperature range between 180{degrees}C to 330{degrees}C. Hence, CMFS seem to be difficult to apply. However, solution annealed austenitic stainless steels are also difficult to apply as the maximum stress level at the container will be higher than the design stress. The solution to the problem is very likely to use advanced low-activation martensitic/ferritic steels (LAMS) developed by the fusion materials community though the present database on the materials is still very limited.« less

OGS#PETSc approach for robust and efficient simulations of strongly coupled hydrothermal processes in EGS reservoirs

NASA Astrophysics Data System (ADS)

Watanabe, Norihiro; Blucher, Guido; Cacace, Mauro; Kolditz, Olaf

2016-04-01

A robust and computationally efficient solution is important for 3D modelling of EGS reservoirs. This is particularly the case when the reservoir model includes hydraulic conduits such as induced or natural fractures, fault zones, and wellbore open-hole sections. The existence of such hydraulic conduits results in heterogeneous flow fields and in a strengthened coupling between fluid flow and heat transport processes via temperature dependent fluid properties (e.g. density and viscosity). A commonly employed partitioned solution (or operator-splitting solution) may not robustly work for such strongly coupled problems its applicability being limited by small time step sizes (e.g. 5-10 days) whereas the processes have to be simulated for 10-100 years. To overcome this limitation, an alternative approach is desired which can guarantee a robust solution of the coupled problem with minor constraints on time step sizes. In this work, we present a Newton-Raphson based monolithic coupling approach implemented in the OpenGeoSys simulator (OGS) combined with the Portable, Extensible Toolkit for Scientific Computation (PETSc) library. The PETSc library is used for both linear and nonlinear solvers as well as MPI-based parallel computations. The suggested method has been tested by application to the 3D reservoir site of Groß Schönebeck, in northern Germany. Results show that the exact Newton-Raphson approach can also be limited to small time step sizes (e.g. one day) due to slight oscillations in the temperature field. The usage of a line search technique and modification of the Jacobian matrix were necessary to achieve robust convergence of the nonlinear solution. For the studied example, the proposed monolithic approach worked even with a very large time step size of 3.5 years.

High-order solution methods for grey discrete ordinates thermal radiative transfer

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

Maginot, Peter G., E-mail: maginot1@llnl.gov; Ragusa, Jean C., E-mail: jean.ragusa@tamu.edu; Morel, Jim E., E-mail: morel@tamu.edu

This work presents a solution methodology for solving the grey radiative transfer equations that is both spatially and temporally more accurate than the canonical radiative transfer solution technique of linear discontinuous finite element discretization in space with implicit Euler integration in time. We solve the grey radiative transfer equations by fully converging the nonlinear temperature dependence of the material specific heat, material opacities, and Planck function. The grey radiative transfer equations are discretized in space using arbitrary-order self-lumping discontinuous finite elements and integrated in time with arbitrary-order diagonally implicit Runge–Kutta time integration techniques. Iterative convergence of the radiation equation ismore » accelerated using a modified interior penalty diffusion operator to precondition the full discrete ordinates transport operator.« less

High-order solution methods for grey discrete ordinates thermal radiative transfer

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

Maginot, Peter G.; Ragusa, Jean C.; Morel, Jim E.

This paper presents a solution methodology for solving the grey radiative transfer equations that is both spatially and temporally more accurate than the canonical radiative transfer solution technique of linear discontinuous finite element discretization in space with implicit Euler integration in time. We solve the grey radiative transfer equations by fully converging the nonlinear temperature dependence of the material specific heat, material opacities, and Planck function. The grey radiative transfer equations are discretized in space using arbitrary-order self-lumping discontinuous finite elements and integrated in time with arbitrary-order diagonally implicit Runge–Kutta time integration techniques. Iterative convergence of the radiation equation ismore » accelerated using a modified interior penalty diffusion operator to precondition the full discrete ordinates transport operator.« less

High-order solution methods for grey discrete ordinates thermal radiative transfer

DOE PAGES

Maginot, Peter G.; Ragusa, Jean C.; Morel, Jim E.

2016-09-29

This paper presents a solution methodology for solving the grey radiative transfer equations that is both spatially and temporally more accurate than the canonical radiative transfer solution technique of linear discontinuous finite element discretization in space with implicit Euler integration in time. We solve the grey radiative transfer equations by fully converging the nonlinear temperature dependence of the material specific heat, material opacities, and Planck function. The grey radiative transfer equations are discretized in space using arbitrary-order self-lumping discontinuous finite elements and integrated in time with arbitrary-order diagonally implicit Runge–Kutta time integration techniques. Iterative convergence of the radiation equation ismore » accelerated using a modified interior penalty diffusion operator to precondition the full discrete ordinates transport operator.« less

Ion temperature gradient mode driven solitons and shocks

NASA Astrophysics Data System (ADS)

Zakir, U.; Adnan, Muhammad; Haque, Q.; Qamar, Anisa; Mirza, Arshad M.

2016-04-01

Ion temperature gradient (ITG) driven solitons and shocks are studied in a plasma having gradients in the equilibrium number density and equilibrium ion temperature. In the linear regime, it is found that the ion temperature and the ratio of the gradient scale lengths, ηi=Ln/LT , affect both the real frequency and the growth rate of the ITG driven wave instability. In the nonlinear regime, for the first time we derive a Korteweg de Vries-type equation for the ITG mode, which admits solitary wave solution. It is found that the ITG mode supports only compressive solitons. Further, it is noticed that the soliton amplitude and width are sensitive to the parameter ηi=Ln/LT . Second, in the presence of dissipation in the system, we obtain a Burger type equation, which admits the shock wave solution. This work may be useful to understand the low frequency electrostatic modes in inhomogeneous electron-ion plasma having density and ion temperature gradients. For illustration, the model has been applied to tokamak plasma.

Numerical Modeling of High-Temperature Corrosion Processes

NASA Technical Reports Server (NTRS)

Nesbitt, James A.

1995-01-01

Numerical modeling of the diffusional transport associated with high-temperature corrosion processes is reviewed. These corrosion processes include external scale formation and internal subscale formation during oxidation, coating degradation by oxidation and substrate interdiffusion, carburization, sulfidation and nitridation. The studies that are reviewed cover such complexities as concentration-dependent diffusivities, cross-term effects in ternary alloys, and internal precipitation where several compounds of the same element form (e.g., carbides of Cr) or several compounds exist simultaneously (e.g., carbides containing varying amounts of Ni, Cr, Fe or Mo). In addition, the studies involve a variety of boundary conditions that vary with time and temperature. Finite-difference (F-D) techniques have been applied almost exclusively to model either the solute or corrodant transport in each of these studies. Hence, the paper first reviews the use of F-D techniques to develop solutions to the diffusion equations with various boundary conditions appropriate to high-temperature corrosion processes. The bulk of the paper then reviews various F-D modeling studies of diffusional transport associated with high-temperature corrosion.

Electrical, structural and morphological properties of chemically sprayed F-doped ZnO films: effect of the ageing-time of the starting solution, solvent and substrate temperature

NASA Astrophysics Data System (ADS)

Guillén-Santiago, A.; Olvera, M. De La L.; Maldonado, A.; Asomoza, R.; Acosta, D. R.

2004-04-01

Conductive and highly transparent fluorine-doped zinc oxide (ZnO:F) thin films were deposited onto glass substrates by the chemical spray technique, using zinc acetate and hydrofluoric acid as precursors. Electrical, structural, morphological and optical characteristics were analyzed as a function of the ageing-time of the starting solution, alcoholic solvent type (methanol or ethanol) and the substrate temperature. The results show that these variables play a crucial role on the physical properties measured. The growth rates obtained were of 3 nm/s, showing that the chemical species involved are adequate for the film growth. The effect of the solution ageing-time on the electrical properties was monitored along three weeks. A gradual resistivity decrease with the ageing-time was observed, until a minimum value is reached, at 7 or 9 days depending on the alcohol employed. Films deposited after this time have resistivity values slightly higher. All the films were polycrystalline, with a hexagonal wurtzite structure whose preferential growth is strongly dependent on the deposition variables. Under optimal deposition conditions, ZnO:F films with a high transmittance in the visible spectrum (>85%), resistivity as low as 7 × 10-3 cm and maximum electronic mobility around of 4 cm2/(V-s) were obtained.

Practical development of continuous supercritical fluid process using high pressure and high temperature micromixer

NASA Astrophysics Data System (ADS)

Kawasaki, Shin-Ichiro; Sue, Kiwamu; Ookawara, Ryuto; Wakashima, Yuichiro; Suzuki, Akira

2015-12-01

In the synthesis of metal oxide fine particles by continuous supercritical hydrothermal method, the particle characteristics are greatly affected by not only the reaction conditions (temperature, pressure, residence time, concentration, etc.), but also the heating rate from ambient to reaction temperature. Therefore, the heating method by direct mixing of starting solution at room temperature with supercritical water is a key technology for the particle production having smaller size and narrow distribution. In this paper, mixing engineering study through comparison between conventional T-shaped mixers and recently developed swirl mixers was carried out in the hydrothermal synthesis of NiO nanoparticles from Ni(NO3)2 aqueous solution at 400 °C and 30 MPa. Inner diameter in the mixers and total flow rates were varied. Furthermore, the heating rate was calculated by computational fluid dynamics (CFD) simulation. Relationship between the heating rate and the average particle size were discussed. It was clarified that the miniaturization of mixer inner diameter and the use of the swirl flow were effective for improving mixing performance and contributed to produce small and narrow distribution particle under same experimental condition of flow rate, temperature, pressure, residence time, and concentration of the starting materials. We have focused the mixer optimization due to a difference in fluid viscosity.

Chitosan-based thermosensitive hydrogel as a promising ocular drug delivery system: preparation, characterization, and in vivo evaluation.

PubMed

Chen, Xingwei; Li, Xinru; Zhou, Yanxia; Wang, Xiaoning; Zhang, Yanhui; Fan, Yating; Huang, Yanqing; Liu, Yan

2012-11-01

The purpose of this study was to evaluate the feasibility of in situ thermosensitive hydrogel based on chitosan in combination with disodium α-d-Glucose 1-phosphate (DGP) for ocular drug delivery system. Aqueous solution of chitosan/DGP underwent sol-gel transition as temperature increased which was flowing sol at room temperature and then turned into non-flowing hydrogel at physiological temperature. The properties of gels were characterized regarding gelation time, gelation temperature, and morphology. The sol-to-gel phase transition behaviors were affected by the concentrations of chitosan, DGP and the model drug levocetirizine dihydrochloride (LD). The developed hydrogel presented a characteristic of a rapid release at the initial period followed by a sustained release and remarkably enhanced the cornea penetration of LD. The results of ocular irritation demonstrated the excellent ocular tolerance of the hydrogel. The ocular residence time for the hydrogel was significantly prolonged compared with eye drops. The drug-loaded hydrogel produced more effective anti-allergic conjunctivitis effects compared with LD aqueous solution. These results showed that the chitosan/DGP thermosensitive hydrogel could be used as an ideal ocular drug delivery system in terms of the suitable sol-gel transition temperature, mild pH environment in the hydrogel as well as the organic solvent free.

Closed Form Solutions for Unsteady Free Convection Flow of a Second Grade Fluid over an Oscillating Vertical Plate

PubMed Central

Ali, Farhad; Khan, Ilyas; Shafie, Sharidan

2014-01-01

Closed form solutions for unsteady free convection flows of a second grade fluid near an isothermal vertical plate oscillating in its plane using the Laplace transform technique are established. Expressions for velocity and temperature are obtained and displayed graphically for different values of Prandtl number Pr, thermal Grashof number Gr, viscoelastic parameter α, phase angle ωτ and time τ. Numerical values of skin friction τ 0 and Nusselt number Nu are shown in tables. Some well-known solutions in literature are reduced as the limiting cases of the present solutions. PMID:24551033

Asymptotic solution of Fokker-Planck equation for plasma in Paul traps

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

Shah, Kushal

2010-05-15

An exact analytic solution of the Vlasov equation for the plasma distribution in a Paul trap is known to be a Maxwellian and thus, immune to collisions under the assumption of infinitely fast relaxation [K. Shah and H. S. Ramachandran, Phys. Plasmas 15, 062303 (2008)]. In this paper, it is shown that even for a more realistic situation of finite time relaxation, solutions of the Fokker-Planck equation lead to an equilibrium solution of the form of a Maxwellian with oscillatory temperature. This shows that the rf heating observed in Paul traps cannot be caused due to collisional effects alone.

Variable anodic thermal control coating

NASA Technical Reports Server (NTRS)

Gilliland, C. S.; Duckett, J. (Inventor)

1983-01-01

A process for providing a thermal control solar stable surface coating for aluminum surfaces adapted to be exposed to solar radiation wherein selected values within the range of 0.10 to 0.72 thermal emittance (epsilon sub tau) and 0.2 to 0.4 solar absorptance (alpha subs) are reproducibly obtained by anodizing the surface area in a chromic acid solution for a selected period of time. The rate voltage and time, along with the parameters of initial epsilon sub tau and alpha subs, temperature of the chromic acid solution, acid concentration of the solution and the material anodized determines the final values of epsilon/tau sub and alpha sub S. 9 Claims, 5 Drawing Figures.

A comparative study on the electrochemical corrosion behavior of iron and X-65 steel in 4.0 wt % sodium chloride solution after different exposure intervals.

PubMed

Sherif, El-Sayed M

2014-07-09

In this work, the results obtained from studying the anodic dissolution of pure iron and API X-65 5L pipeline steel after 40 min and 12 h exposure period in 4.0 wt % NaCl solutions at room temperature were reported. Potential-time, electrochemical impedance spectroscopy, potentiodynamic polarization, and chronoamperometric current-time at constant potential techniques were employed. It has been found that the iron electrode corrodes in the chloride test solutions faster than the API X-65 5L steel does under the same conditions. Increasing the exposure period for the electrodes from 40 min to 12 h showed a significant reduction in the corrosion parameters for both iron and steel in the 4.0 wt % NaCl solution. Results together confirmed clearly that the X-65 steel is superior to iron against corrosion in sodium chloride solutions.

A fast solution switching system with temperature control for single cell measurements

PubMed Central

Koh, Duk-Su; Chen, Liangyi; Ufret-Vincenty, Carmen A.; Jung, Seung-Ryoung

2011-01-01

This article describes a perfusion system for biophysical single cell experiments at the physiological temperature. Our system regulates temperature of test solutions using a small heat exchanger that includes several capillaries. Water circulating inside the heat exchanger warms or cools test solutions flowing inside the capillaries. Temperature-controlled solutions are delivered directly to a single cell(s) through a multibarreled manifold that switches solutions bathing a cell in less than 1 s. This solution exchange is optimal for patch clamp, single-cell microamperometry, and microfluorometry experiments. Using this system, we demonstrate that exocytosis from pancreatic β cells and activation of TRPV1 channels are temperature sensitive. We also discuss how to measure local temperature near a single cell under investigation. PMID:21536068

Self-adaptive difference method for the effective solution of computationally complex problems of boundary layer theory

NASA Technical Reports Server (NTRS)

Schoenauer, W.; Daeubler, H. G.; Glotz, G.; Gruening, J.

1986-01-01

An implicit difference procedure for the solution of equations for a chemically reacting hypersonic boundary layer is described. Difference forms of arbitrary error order in the x and y coordinate plane were used to derive estimates for discretization error. Computational complexity and time were minimized by the use of this difference method and the iteration of the nonlinear boundary layer equations was regulated by discretization error. Velocity and temperature profiles are presented for Mach 20.14 and Mach 18.5; variables are velocity profiles, temperature profiles, mass flow factor, Stanton number, and friction drag coefficient; three figures include numeric data.

Oxidation kinetics of a continuous carbon phase in a nonreactive matrix

NASA Technical Reports Server (NTRS)

Eckel, Andrew J.; Cawley, James D.; Parthasarathy, Triplicane A.

1995-01-01

Analytical solutions of and experimental results on the oxidation kinetics of carbon in a pore are presented. Reaction rate, reaction sequence, oxidant partial pressure, total system pressure, pore/crack dimensions, and temperature are analyzed with respect to the influence of each on an overall linear-parabolic rate relationship. Direct measurement of carbon recession is performed using two microcomposite model systems oxidized in the temperature range of 700 to 1200 C, and for times to 35 h. Experimental results are evaluated using the derived analytical solutions. Implications on the oxidation resistance of continuous-fiber-reinforced ceramic-matrix composites containing a carbon constituent are discussed.

Observation of glassy state relaxation during annealing of frozen sugar solutions by X-ray computed tomography.

PubMed

Nakagawa, Kyuya; Tamiya, Shinri; Do, Gabsoo; Kono, Shinji; Ochiai, Takaaki

2018-06-01

Glassy phase formation in a frozen product determines various properties of the freeze-dried products. When an aqueous solution is subjected to freezing, a glassy phase forms as a consequence of freeze-concentration. During post-freezing annealing, the relaxation of the glassy phase and the ripening of ice crystals (i.e. Ostwald ripening) spontaneously occur, where the kinetics are controlled by the annealing and glass transition temperatures. This study was motivated to observe the progress of glassy state relaxation separate from ice coarsening during annealing. X-ray computed tomography (CT) was used to observe a frozen and post-freezing annealed solutions by using monochromatized X-ray from the synchrotron radiation. CT images were successfully obtained, and the frozen matrix were analyzed based on the gray level values that were equivalent to the linear X-ray attenuation coefficients of the observed matters. The CT images obtained from rapidly frozen sucrose and dextrin solutions with different concentrations gave clear linear relationships between the linear X-ray attenuation coefficients values and the solute concentrations. It was confirmed that the glassy state relaxation progressed as increasing annealing time, and this trend was larger in the order of the glass transition temperature of the maximally freeze-concentrated phase. The sucrose-water system required nearly 20 h of annealing time at -5 °C for the completion of the glassy phase relaxation, whereas dextrin-water systems required much longer periods because of their higher glass transition temperatures. The trends of ice coarsening, however, did not perfectly correspond to the trends of the relaxation, suggesting that the glassy phase relaxation and Ostwald ripening would jointly control the ice crystal growth/ripening kinetics, and the dominant mechanism differed by the annealing stage. Copyright © 2018 Elsevier B.V. All rights reserved.

Improved vertical streambed flux estimation using multiple diurnal temperature methods in series

USGS Publications Warehouse

Irvine, Dylan J.; Briggs, Martin A.; Cartwright, Ian; Scruggs, Courtney; Lautz, Laura K.

2017-01-01

Analytical solutions that use diurnal temperature signals to estimate vertical fluxes between groundwater and surface water based on either amplitude ratios (Ar) or phase shifts (Δϕ) produce results that rarely agree. Analytical solutions that simultaneously utilize Ar and Δϕ within a single solution have more recently been derived, decreasing uncertainty in flux estimates in some applications. Benefits of combined (ArΔϕ) methods also include that thermal diffusivity and sensor spacing can be calculated. However, poor identification of either Ar or Δϕ from raw temperature signals can lead to erratic parameter estimates from ArΔϕ methods. An add-on program for VFLUX 2 is presented to address this issue. Using thermal diffusivity selected from an ArΔϕ method during a reliable time period, fluxes are recalculated using an Ar method. This approach maximizes the benefits of the Ar and ArΔϕ methods. Additionally, sensor spacing calculations can be used to identify periods with unreliable flux estimates, or to assess streambed scour. Using synthetic and field examples, the use of these solutions in series was particularly useful for gaining conditions where fluxes exceeded 1 m/d.

A low temperature furnace for solution crystal growth on the International Space Station

NASA Astrophysics Data System (ADS)

Baç, Nurcan; Harpster, Joseph; Maston, Robert A.; Sacco, Albert

2000-01-01

The Zeolite Crystal Growth Furnace Unit (ZCG-FU) is the first module in an integrated payload designed for low temperature crystal growth in solutions on the International Space Station (ISS). This payload is scheduled to fly on the ISS flight 7A.1 in an EXPRESS rack. Its name originated from early shuttle flight experiments limited to the growth of zeolite crystals but has since grown to include other materials of significant commercial interest using the solution method of crystal growth. Zeolites, ferroelectrics, piezeoelectrics and silver halides are some of the materials considered. The ZCG-FU experiment consists of a furnace unit and its electronic control system, and mechanically complex, crystal growth autoclaves suitable for use with a particular furnace and solution. The ZCG facility is being designed to grow into four independent furnaces controlled by IZECS (Improved Zeolite Electronic Control System). IZECS provides monitoring of critical parameters, data logging, safety monitoring, air-to-ground control and operator interfacing. It is suitable for controlling the four furnaces either individually or all at one time. It also contains the power management solid-state drivers and switches for the ZCG-FU furnace. The furnace contains 19 tubes operating at three different temperature zones. .

Influence of perfusate temperature on nasal potential difference.

PubMed

Bronsveld, Inez; Vermeulen, François; Sands, Dorotha; Leal, Teresinha; Leonard, Anissa; Melotti, Paola; Yaakov, Yasmin; de Nooijer, Roel; De Boeck, Kris; Sermet, Isabelle; Wilschanski, Michael; Middleton, Peter G

2013-08-01

Nasal potential difference (NPD) quantifies abnormal ion transport in cystic fibrosis. It has gained acceptance as an outcome measure for the investigation of new therapies. To quantify the effect of solution temperature on NPD, we first examined the effect of switching from room temperature (20-25°C) to warmed (32-37°C) solutions and vice versa during each perfusion step. Secondly, standard protocols were repeated at both temperatures in the same subjects. Changing solution temperature did not alter NPD during perfusion with Ringer's solution (<1 mV) (p>0.1). During perfusion with zero chloride solution, changing from room temperature to warmed solutions tended to decrease absolute NPD (i.e. it became less negative) by 0.9 mV (p>0.1); changing from warmed to room temperature increased NPD by 2.1 mV (p<0.05). During isoprenaline perfusion, changing from room temperature to warmed solutions increased NPD by 1.5 mV (p<0.01) and from warmed to room temperature decreased NPD by 1.4 mV (p<0.05). For full protocols at room temperature or warmed in the same subjects, mean values were similar (n = 24). During warmed perfusion, group results for total chloride response had a larger standard deviation. As this increased variability will probably decrease the power of trials, this study suggests that solutions at room temperature should be recommended for the measurement of NPD.

High throughput integrated thermal characterization with non-contact optical calorimetry

NASA Astrophysics Data System (ADS)

Hou, Sichao; Huo, Ruiqing; Su, Ming

2017-10-01

Commonly used thermal analysis tools such as calorimeter and thermal conductivity meter are separated instruments and limited by low throughput, where only one sample is examined each time. This work reports an infrared based optical calorimetry with its theoretical foundation, which is able to provide an integrated solution to characterize thermal properties of materials with high throughput. By taking time domain temperature information of spatially distributed samples, this method allows a single device (infrared camera) to determine the thermal properties of both phase change systems (melting temperature and latent heat of fusion) and non-phase change systems (thermal conductivity and heat capacity). This method further allows these thermal properties of multiple samples to be determined rapidly, remotely, and simultaneously. In this proof-of-concept experiment, the thermal properties of a panel of 16 samples including melting temperatures, latent heats of fusion, heat capacities, and thermal conductivities have been determined in 2 min with high accuracy. Given the high thermal, spatial, and temporal resolutions of the advanced infrared camera, this method has the potential to revolutionize the thermal characterization of materials by providing an integrated solution with high throughput, high sensitivity, and short analysis time.

Low temperature synthesis of CaO-SiO2 glasses having stable liquid-liquid immiscibility by sol-gel process

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.

1990-01-01

Calcium silicate glass compositions lying within the liquid-liquid immiscibility dome of the phase diagram, which could not have been prepared by the conventional melting method, were synthesized by the sol-gel process. Hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) solutions containing up to 20 mol percent calcium nitrate resulted in the formation of clear and transparent gels. The gel formation time decreased with increase in water:TEOS mole ratio, calcium content, and the reaction temperature. Smaller values of gel times in the presence of calcium nitrate are probably caused by lowering of the ionic charge on the sol particles by the salt present. The gelation activation energy, E(sub gel), was evaluated from temperature dependence of the gel time. Presence of Ca(2+) ions or the water:TEOS mole ratio did not have an appreciable effect on the value of E(sub gel). Presence of glycerol in the solution helped in the formation of crack-free monolithic gel specimens. Chemical and structural changes occurring in the gels, as a function of the heat treatments, have been monitored using DTA, TGA, IR-spectroscopy, x ray diffraction, surface area and pore size distribution measurements.

Low temperature synthesis of CaO-SiO2 glasses having stable liquid-liquid immiscibility by the sol-gel process

NASA Technical Reports Server (NTRS)

Bansal, N. P.

1992-01-01

Calcium silicate glass compositions lying within the liquid-liquid immiscibility dome of the phase diagram, which could not have been prepared by the conventional melting method, were synthesized by the sol-gel process. Hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) solutions containing up to 20 mol percent calcium nitrate resulted in the formation of clear and transparent gels. The gel formation time decreased with increase in water: TEOS mole ratio, calcium content, and the reaction temperature. Smaller values of gel times in the presence of calcium nitrate are probably caused by lowering of the ionic charge on the sol particles by the salt present. The gelation activation energy, E(sub gel), was evaluated from temperature dependence of the gel time. Presence of Ca(2+) ions or the water:TEOS mole ratio did not have an appreciable effect on the value of E(sub gel). Presence of glycerol in the solution helped in the formation of crack-free monolithic gel specimens. Chemical and structural changes occurring in the gels, as a function of the heat treatments, have been monitored using DTA, TGA, IR-spectroscopy, X-ray diffraction, surface area and pore size distribution measurements.

Atmospheric carbon dioxide and chlorofluoromethanes - Combined effects on stratospheric ozone, temperature, and surface temperature

NASA Technical Reports Server (NTRS)

Callis, L. B.; Natarajan, M.

1981-01-01

The effects of combined CO2 and CFCl3 and CF2Cl2 time-dependent scenarios on atmospheric O3 and temperature are described; the steady-state levels of O3 and surface temperature, to which the chlorofluoromethane scenario tends in the presence of twice and four time ambient CO2, are examined; and surface temperature changes, caused by the combined effects, are established. A description of the model and of the experiments is presented. Results indicate that (1) the total ozone time history is significantly different from that due to the chlorofluoromethane alone; (2) a local ozone minimum occurs in the upper stratosphere about 45 years from the present with a subsequent ozone increase, then decline; and (3) steady-state solutions indicate that tropospheric temperature and water vapor increases, associated with increased infrared opacity, cause significant changes in tropospheric ozone levels for 2 x CO2 and 4 x CO2, without the addition of chlorofluoromethanes.

Statistical analysis of environmental variability within the CELSS breadboard project's biomass production chamber

NASA Technical Reports Server (NTRS)

Stutte, G. W.; Chetirkin, P. V.; Mackowiak, C. L.; Fortson, R. E.

1993-01-01

Variability in the aerial and root environments of NASA's Breadboard Project's Biomass Production Chamber (BPC) was determined. Data from two lettuce and two potato growouts were utilized. One growout of each crop was conducted prior to separating the upper and lower chambers; the other was subsequent to separation. There were little or no differences in pH, EC, or solution temperature between the upper and lower chamber or within a chamber. Variation in the aerial environment within a chamber was two to three times greater than variation between chambers for air temperature, relative humidity, and PPF. High variability in air velocity, relative to tray position, was observed. Separating the BPC had no effect on PPF, air velocity, solution temperature, pH, or EC. Separation reduced the gradient in air temperature and relative humidity between the upper and lower chambers, but increased the variability within a chamber. Variation between upper and lower chambers was within 5 percent of environmental set-points and of little or no physiological significance. In contrast, the variability within a chamber limits the capability of the BPC to generate statistically reliable data from individual tray treatments at this time.

Solute partitioning under continuous cooling conditions as a cooling rate indicator. [in lunar rocks

NASA Technical Reports Server (NTRS)

Onorato, P. I. K.; Hopper, R. W.; Yinnon, H.; Uhlmann, D. R.; Taylor, L. A.; Garrison, J. R.; Hunter, R.

1981-01-01

A model of solute partitioning in a finite body under conditions of continuous cooling is developed for the determination of cooling rates from concentration profile data, and applied to the partitioning of zirconium between ilmenite and ulvospinel in the Apollo 15 Elbow Crater rocks. Partitioning in a layered composite solid is described numerically in terms of concentration profiles and diffusion coefficients which are functions of time and temperature, respectively; a program based on the model can be used to calculate concentration profiles for various assumed cooling rates given the diffusion coefficients in the two phases and the equilibrium partitioning ratio over a range of temperatures. In the case of the Elbow Rock gabbros, the cooling rates are calculated from measured concentration ratios 10 microns from the interphase boundaries under the assumptions of uniform and equilibrium initial conditions at various starting temperatures. It is shown that the specimens could not have had uniform concentrations profiles at the previously suggested initial temperature of 1350 K. It is concluded that even under conditions where the initial temperature, grain sizes and solute diffusion coefficients are not well characterized, the model can be used to estimate the cooling rate of a grain assemblage to within an order of magnitude.

Development of improved low-strain creep strength in Cabot alloy R-41 sheet. [nickel base sheet alloy for reentry shielding

NASA Technical Reports Server (NTRS)

Rothman, M. F.

1984-01-01

The feasibility of improving the low-strain creep properties of a thin gauge nickel base sheet alloy through modified heat treatment or through development of a preferred crystal-lographic texture was investigated. The basic approach taken to improve the creep strength of the material by heat treatment was to increase grain size by raising the solution treatment temperature for the alloy to the range of 1420 K to 1475 K (2100 F to 2200 F). The key technical issue involved was maintenance of adequate tensile ductility following the solutioning of M6C primary carbides during the higher temperature solution treatment. The approach to improve creep properties by developing a sheet texture involved varying both annealing temperatures and the amount of prior cold work. Results identified a heat treatment for alloy R-14 sheet which yields a substantial creep-life advantage at temperatures above 1090 K (1500 F) when compared with material given the standard heat treatment. At the same time, this treatment provides reasonable tensile ductility over the entire temperature range of interest. The mechanical properties of the material given the new heat treatment are compared with those for material given the standard heat treatment. Attempts to improve creep strength by developing a sheet texture were unsuccessful.

Heat and mass transport during a groundwater replenishment trial in a highly heterogeneous aquifer

NASA Astrophysics Data System (ADS)

Seibert, Simone; Prommer, Henning; Siade, Adam; Harris, Brett; Trefry, Mike; Martin, Michael

2014-12-01

Changes in subsurface temperature distribution resulting from the injection of fluids into aquifers may impact physiochemical and microbial processes as well as basin resource management strategies. We have completed a 2 year field trial in a hydrogeologically and geochemically heterogeneous aquifer below Perth, Western Australia in which highly treated wastewater was injected for large-scale groundwater replenishment. During the trial, chloride and temperature data were collected from conventional monitoring wells and by time-lapse temperature logging. We used a joint inversion of these solute tracer and temperature data to parameterize a numerical flow and multispecies transport model and to analyze the solute and heat propagation characteristics that prevailed during the trial. The simulation results illustrate that while solute transport is largely confined to the most permeable lithological units, heat transport was also affected by heat exchange with lithological units that have a much lower hydraulic conductivity. Heat transfer by heat conduction was found to significantly influence the complex temporal and spatial temperature distribution, especially with growing radial distance and in aquifer sequences with a heterogeneous hydraulic conductivity distribution. We attempted to estimate spatially varying thermal transport parameters during the data inversion to illustrate the anticipated correlations of these parameters with lithological heterogeneities, but estimates could not be uniquely determined on the basis of the collected data.

Femtosecond transient absorption, Raman, and electrochemistry studies of tetrasulfonated copper phthalocyanine in water solutions.

PubMed

Abramczyk, H; Brozek-Płuska, B; Kurczewski, K; Kurczewska, M; Szymczyk, I; Krzyczmonik, P; Błaszczyk, T; Scholl, H; Czajkowski, W

2006-07-20

Ultrafast time-resolved electronic spectra of the primary events induced in the copper tetrasulfonated phthalocyanine Cu(tsPc)4-) in aqueous solution has been measured by femtosecond pump-probe transient absorption spectroscopy. The primary events initiated by the absorption of a photon occurring within the femtosecond time scale are discussed on the basis of the electron transfer mechanism between the adjacent phthalocyanine rings proposed recently in our laboratory. The femtosecond transient absorption results are compared with the low temperature emission spectra obtained with Raman spectroscopy and the voltammetric curves.

Solidification of a binary mixture

NASA Technical Reports Server (NTRS)

Antar, B. N.

1982-01-01

The time dependent concentration and temperature profiles of a finite layer of a binary mixture are investigated during solidification. The coupled time dependent Stefan problem is solved numerically using an implicit finite differencing algorithm with the method of lines. Specifically, the temporal operator is approximated via an implicit finite difference operator resulting in a coupled set of ordinary differential equations for the spatial distribution of the temperature and concentration for each time. Since the resulting differential equations set form a boundary value problem with matching conditions at an unknown spatial point, the method of invariant imbedding is used for its solution.

Solutions for the diurnally forced advection-diffusion equation to estimate bulk fluid velocity and diffusivity in streambeds from temperature time series

NASA Astrophysics Data System (ADS)

Luce, C.; Tonina, D.; Gariglio, F. P.; Applebee, R.

2012-12-01

Differences in the diurnal variations of temperature at different depths in streambed sediments are commonly used for estimating vertical fluxes of water in the streambed. We applied spatial and temporal rescaling of the advection-diffusion equation to derive two new relationships that greatly extend the kinds of information that can be derived from streambed temperature measurements. The first equation provides a direct estimate of the Peclet number from the amplitude decay and phase delay information. The analytical equation is explicit (e.g. no numerical root-finding is necessary), and invertable. The thermal front velocity can be estimated from the Peclet number when the thermal diffusivity is known. The second equation allows for an independent estimate of the thermal diffusivity directly from the amplitude decay and phase delay information. Several improvements are available with the new information. The first equation uses a ratio of the amplitude decay and phase delay information; thus Peclet number calculations are independent of depth. The explicit form also makes it somewhat faster and easier to calculate estimates from a large number of sensors or multiple positions along one sensor. Where current practice requires a priori estimation of streambed thermal diffusivity, the new approach allows an independent calculation, improving precision of estimates. Furthermore, when many measurements are made over space and time, expectations of the spatial correlation and temporal invariance of thermal diffusivity are valuable for validation of measurements. Finally, the closed-form explicit solution allows for direct calculation of propagation of uncertainties in error measurements and parameter estimates, providing insight about error expectations for sensors placed at different depths in different environments as a function of surface temperature variation amplitudes. The improvements are expected to increase the utility of temperature measurement methods for studying groundwater-surface water interactions across space and time scales. We discuss the theoretical implications of the new solutions supported by examples with data for illustration and validation.

Thermal Buckling Analysis of Rectangular Panels Subjected to Humped Temperature Profile Heating

NASA Technical Reports Server (NTRS)

Ko, William I.

2004-01-01

This research investigates thermal buckling characteristics of rectangular panels subjected to different types of humped temperature profile heating. Minimum potential energy and finite-element methods are used to calculate the panel buckling temperatures. The two methods give fairly close thermal buckling solutions. 'Buckling temperature magnification factor of the first kind, eta' is established for the fixed panel edges to scale up the buckling solution of uniform temperature loading case to give the buckling solution of the humped temperature profile loading cases. Also, 'buckling temperature magnification factor of the second kind, xi' is established for the free panel edges to scale up the buckling solution of humped temperature profile loading cases with unheated boundary heat sinks to give the buckling solutions when the boundary heat sinks are heated up.

Stability of sugar solutions: a novel study of the epimerization kinetics of lactose in water.

PubMed

Jawad, Rim; Drake, Alex F; Elleman, Carole; Martin, Gary P; Warren, Frederick J; Perston, Benjamin B; Ellis, Peter R; Hassoun, Mireille A; Royall, Paul G

2014-07-07

This article reports on the stereochemical aspects of the chemical stability of lactose solutions stored between 25 and 60 °C. The lactose used for the preparation of the aqueous solutions was α-lactose monohydrate with an anomer purity of 96% α and 4% β based on the supplied certificate of analysis (using a GC analytical protocol), which was further confirmed here by nuclear magnetic resonance (NMR) analysis. Aliquots of lactose solutions were collected at different time points after the solutions were prepared and freeze-dried to remove water and halt epimerization for subsequent analysis by NMR. Epimerization was also monitored by polarimetry and infrared spectroscopy using a specially adapted Fourier transform infrared attenuated total reflectance (FTIR-ATR) method. Hydrolysis was analyzed by ion chromatography. The three different analytical approaches unambiguously showed that the epimerization of lactose in aqueous solution follows first order reversible kinetics between 25 to 60 °C. The overall rate constant was 4.4 × 10(-4) s(-1) ± 0.9 (± standard deviation (SD)) at 25 °C. The forward rate constant was 1.6 times greater than the reverse rate constant, leading to an equilibrium constant of 1.6 ± 0.1 (±SD) at 25 °C. The rate of epimerization for lactose increased with temperature and an Arrhenius plot yielded an activation energy of +52.3 kJ/mol supporting the hypothesis that the mechanism of lactose epimerization involves the formation of extremely short-lived intermediate structures. The main mechanism affecting lactose stability is epimerization, as no permanent hydrolysis or chemical degradation was observed. When preparing aqueous solutions of lactose, immediate storage in an ice bath at 0 °C will allow approximately 3 min (180 s) of analysis time before the anomeric ratio alters significantly (greater than 1%) from the solid state composition of the starting material. In contrast a controlled anomeric composition (~38% α and ~62% β) will be achieved if an aqueous solution is left to equilibrate for over 4 h at 25 °C, while increasing the temperature up to 60 °C rapidly reduces the required equilibration time.

Physico-chemical stability of eribulin mesylate containing concentrate and ready-to-administer solutions.

PubMed

Spindeldreier, Kirsten; Thiesen, Judith; Lipp, Hans-Peter; Krämer, Irene

2014-06-01

The aim of this study was to determine the stability of commercially available eribulin mesylate containing injection solution as well as diluted ready-to-administer solutions stored under refrigeration or at room temperature. Stability was studied by a novel developed stability-indicating reversed-phase high-performance liquid chromatography (RP-HPLC) assay with ultraviolet detection (detection wavelength 200 nm). Triplicate test solutions of eribulin mesylate containing injection concentrate (0.5 mg/mL) and with 0.9% sodium chloride solution diluted ready-to-administer preparations (0.205 mg/mL eribulin mesylate in polypropylene (PP) syringes, 0.020 mg/mL eribulin mesylate in polypropylene/polyethylene (PE) bags) were stored protected from light either at room temperature (25) or under refrigeration (2-8). Samples were withdrawn on day 0 (initial), 1, 3, 5, 7, 14, 21 and 28 of storage and assayed. Physical stability was determined by measuring the pH value once a week and checking for visible precipitations or colour changes. The stability tests revealed that concentrations of eribulin mesylate remained unchanged over a period of 28 days irrespective of concentration, container material or storage temperature. Neither colour changes nor visible particles have been observed. The pH value varied slightly over time but remained in the stability favourable range of 5-9. Eribulin mesylate injection (0.5 mg/mL) is physico-chemically stable over a period of 28 days after first puncture of the vial. After dilution with 0.9% NaCl vehicle solution, ready-to-administer eribulin mesylate injection solutions (0.205 mg/mL in PP syringe) and infusion solutions (0.02 mg/mL in prefilled PP/PE bags) are physico-chemically stable for a period of at least four weeks either refrigerated or stored at room temperature. For microbiological reasons storage under refrigeration is recommended.

Effects of Temperature on Solute Transport Parameters in Differently-Textured Soils at Saturated Condition

NASA Astrophysics Data System (ADS)

Hamamoto, S.; Arihara, M.; Kawamoto, K.; Nishimura, T.; Komatsu, T.; Moldrup, P.

2014-12-01

Subsurface warming driven by global warming, urban heat islands, and increasing use of shallow geothermal heating and cooling systems such as the ground source heat pump, potentially causes changes in subsurface mass transport. Therefore, understanding temperature dependency of the solute transport characteristics is essential to accurately assess environmental risks due to increased subsurface temperature. In this study, one-dimensional solute transport experiments were conducted in soil columns under temperature control to investigate effects of temperature on solute transport parameters, such as solute dispersion and diffusion coefficients, hydraulic conductivity, and retardation factor. Toyoura sand, Kaolin clay, and intact loamy soils were used in the experiments. Intact loamy soils were taken during a deep well boring at the Arakawa Lowland in Saitama Prefecture, Japan. In the transport experiments, the core sample with 5-cm diameter and 4-cm height was first isotropically consolidated, whereafter 0.01M KCl solution was injected to the sample from the bottom. The concentrations of K+ and Cl- in the effluents were analyzed by an ion chromatograph to obtain solute breakthrough curves. The solute transport parameters were calculated from the breakthrough curves. The experiments were conducted under different temperature conditions (15, 25, and 40 oC). The retardation factor for the intact loamy soils decreased with increasing temperature, while water permeability increased due to reduced viscosity of water at higher temperature. Opposite, the effect of temperature on solute dispersivity for the intact loamy soils was insignificant. The effects of soil texture on the temperature dependency of the solute transport characteristics will be further investigated from comparison of results from differently-textured samples.

Using solute and heat tracers for aquifer characterization in a strongly heterogeneous alluvial aquifer

NASA Astrophysics Data System (ADS)

Sarris, Theo S.; Close, Murray; Abraham, Phillip

2018-03-01

A test using Rhodamine WT and heat as tracers, conducted over a 78 day period in a strongly heterogeneous alluvial aquifer, was used to evaluate the utility of the combined observation dataset for aquifer characterization. A highly parameterized model was inverted, with concentration and temperature time-series as calibration targets. Groundwater heads recorded during the experiment were boundary dependent and were ignored during the inversion process. The inverted model produced a high resolution depiction of the hydraulic conductivity and porosity fields. Statistical properties of these fields are in very good agreement with estimates from previous studies at the site. Spatially distributed sensitivity analysis suggests that both solute and heat transport were most sensitive to the hydraulic conductivity and porosity fields and less sensitive to dispersivity and thermal distribution factor, with sensitivity to porosity greatly reducing outside the monitored area. The issues of model over-parameterization and non-uniqueness are addressed through identifiability analysis. Longitudinal dispersivity and thermal distribution factor are highly identifiable, however spatially distributed parameters are only identifiable near the injection point. Temperature related density effects became observable for both heat and solute, as the temperature anomaly increased above 12 degrees centigrade, and affected down gradient propagation. Finally we demonstrate that high frequency and spatially dense temperature data cannot inform a dual porosity model in the absence of frequent solute concentration measurements.

Correlation of high-temperature stability of alpha-chymotrypsin with 'salting-in' properties of solution.

PubMed

Levitsky VYu; Panova, A A; Mozhaev, V V

1994-01-15

A correlation between the stability of alpha-chymotrypsin against irreversible thermal inactivation at high temperatures (long-term stability) and the coefficient of Setchenov equation as a measure of salting-in/out efficiency of solutes in the Hofmeister series has been found. An increase in the concentration of salting-in solutes (KSCN, urea, guanidinium chloride, formamide) leads to a many-fold decrease of the inactivation rate of the enzyme. In contrast, addition of salting-out solutes has a small effect on the long-term stability of alpha-chymotrypsin at high temperatures. The effects of solutes are additive with respect to their salting-in/out capacities; the stabilizing action of the solutes is determined by the calculated Setchenov coefficient of solution. The correlation is explained by a solute-driven shift of the conformational equilibrium between the 'low-temperature' native and the 'high-temperature' denatured forms of the enzyme within the range of the kinetic scheme put forward in the preceding paper in this journal: irreversible inactivation of the high-temperature form proceeds much more slowly compared with the low-temperature form.

Materials research for passive solar systems: Solid-state phase-change materials

NASA Astrophysics Data System (ADS)

Benson, D. K.; Webb, J. D.; Burrows, R. W.; McFadden, J. D. O.; Christensen, C.

1985-03-01

A set of solid-state phase-change materials is being evaluated for possible use in passive solar thermal energy storage systems. The most promising materials are organic solid solutions of pentaerythritol (C5H12O4), pentaglycerinve (C5H12O3), and neopentyl glycol (C5H12O2). Solid solution mixtures of these compounds can be tailored so that they exhibit solid-to-solid phase transformations at any desired temperature between 25 C and 188 C, and have latent heats of transformation etween 20 and 70 cal/g. Transformation temperatures, specific heats, and latent heats of transformation have been measured for a number of these materials. Limited cyclic experiments suggest that the solid solutions are stable. These phase-change materials exhibit large amounts of undercooling; however, the addition of certain nucleating agents as particulate dispersions in the solid phase-change material greatly reduces this effect. Computer simulations suggest that the use of an optimized solid-state phase-change material in a Trombe wall could provide better performance than a concrete Trombe wall four times thicker and nine times heavier.

Time-Lapse, in Situ Imaging of Ice Crystal Growth Using Confocal Microscopy

PubMed Central

2016-01-01

Ice crystals nucleate and grow when a water solution is cooled below its freezing point. The growth velocities and morphologies of the ice crystals depend on many parameters, such as the temperature of ice growth, the melting temperature, and the interactions of solutes with the growing crystals. Three types of morphologies may appear: dendritic, cellular (or fingerlike), or the faceted equilibrium form. Understanding and controlling which type of morphology is formed is essential in several domains, from biology to geophysics and materials science. Obtaining, in situ, three dimensional observations without introducing artifacts due to the experimental technique is nevertheless challenging. Here we show how we can use laser scanning confocal microscopy to follow in real-time the growth of smoothed and faceted ice crystals in zirconium acetate solutions. Both qualitative and quantitative observations can be made. In particular, we can precisely measure the lateral growth velocity of the crystals, a measure otherwise difficult to obtain. Such observations should help us understand the influence of the parameters that control the growth of ice crystals in various systems. PMID:27917410

[Physical and chemical evaluation during refrigeration storage of salted catfish (Pseudoplatystoma sp.) in brine solution, and packed under vacuum].

PubMed

Rodríguez, Diana; Barrero, Marinela; Kodaira, Makie

2009-06-01

Salting fish in the south Venezuelan towns are still the main method of preserving fish including cutt, and salting fish process, storage and commercialization. As the result, salted-dried fish is particularly susceptible to spoilage by a number of factors, including lipid oxidation, browning meat. Packing salted fish product is an alternative increasing storage life time reducing lost of quality and enhancing the storage time. The present study evaluated the physic, chemist, and sensory quality of fish fillet from cat fish (Pseudoplatystoma sp.) from Apure state, Venezuela. Fillet fish were placed in brine solution at 36% of sodium chloride 1:2 fillet: brine solution; after, they were packed under followed conditions: vacuum, vacuum and storage under refrigeration condition, and room temperature. The results showed significant differences (p < 0.01) for moisture, salt content, and Aw. The fillets packed at vacuum and storage at 4 degrees C were significant different from the resting treatments; not significant differences were presented at room and refrigeration temperature after three moths. The best conditions treatment was vacuum packing and refrigeration at 4 degrees C.

Time-Lapse, in Situ Imaging of Ice Crystal Growth Using Confocal Microscopy.

PubMed

Marcellini, Moreno; Noirjean, Cecile; Dedovets, Dmytro; Maria, Juliette; Deville, Sylvain

2016-11-30

Ice crystals nucleate and grow when a water solution is cooled below its freezing point. The growth velocities and morphologies of the ice crystals depend on many parameters, such as the temperature of ice growth, the melting temperature, and the interactions of solutes with the growing crystals. Three types of morphologies may appear: dendritic, cellular (or fingerlike), or the faceted equilibrium form. Understanding and controlling which type of morphology is formed is essential in several domains, from biology to geophysics and materials science. Obtaining, in situ, three dimensional observations without introducing artifacts due to the experimental technique is nevertheless challenging. Here we show how we can use laser scanning confocal microscopy to follow in real-time the growth of smoothed and faceted ice crystals in zirconium acetate solutions. Both qualitative and quantitative observations can be made. In particular, we can precisely measure the lateral growth velocity of the crystals, a measure otherwise difficult to obtain. Such observations should help us understand the influence of the parameters that control the growth of ice crystals in various systems.

Change the morphology of lithium oxides by Nd-Yag laser beam to use as a sand in water-cooled reactors

NASA Astrophysics Data System (ADS)

Karwi, Abbas Ali Mahmmod

2018-04-01

Laser has many attractive specifications which made it adaptable for material processing. Laser has been taken as a modern heat treatment source to prevent the formation of non-protective oxide layer with intensity equals to (1.31×105 w/cm2), lasing time equals to (300 µs), wave length equals to (1.063 µm), and the spot radius equals to (125 µm). Lithium is depleted through the conventional heat treatment processes. The main factors affected on lithium depletion are temperature and time. Lithium kept as a solid solution at casting method. Micro hardness of the affected zone reaches to acceptable values for various ageing times and hardening depths. The main conventional heat treatment processes are; homogenization, solution heat treatment, and ageing. Alloys prepared with the specific amounts of lithium concentration (2-2.5%). Oxides with different shapes are formed. Temperature distribution, heating, and cooling rates used externally and internally to see the effect of pulse generation by laser on bulk body.

Doxorubicin-induced co-assembling nanomedicines with temperature-sensitive acidic polymer and their in-situ-forming hydrogels for intratumoral administration.

PubMed

Wan, Jiangshan; Geng, Shinan; Zhao, Hao; Peng, Xiaole; Zhou, Qing; Li, Han; He, Ming; Zhao, Yanbing; Yang, Xiangliang; Xu, Huibi

2016-08-10

Doxorubicin (DOX)-induced co-assembling nanomedicines (D-PNAx) with temperature-sensitive PNAx triblock polymers have been developed for regional chemotherapy against liver cancer via intratumoral administration in the present work. Owing to the formation of insoluble DOX carboxylate, D-PNAx nanomedicines showed high drug-loading and entrapment efficacy via a simple mixing of doxorubicin hydrochloride and PNAx polymers. The sustained releasing profile of D-PNA100 nanomedicines indicated that only 9.4% of DOX was released within 1day, and 60% was released during 10days. Based on DOX-induced co-assembling behavior and their temperature sensitive in-situ-forming hydrogels, D-PNA100 nanomedicines showed excellent antitumor activity against H22 tumor using intratumoral administration. In contrast to that by free DOX solution (1.13±0.04 times at 9days) and blank PNA100 (2.11±0.34 times), the tumor volume treated by D-PNA100 had been falling to only 0.77±0.13 times of original tumor volume throughout the experimental period. In vivo biodistribution of DOX indicated that D-PNA100 nanomedicines exhibited much stronger DOX retention in tumor tissues than free DOX solution via intratumoral injection. D-PNA100 nanomedicines were hopeful to be developed as new temperature sensitive in-situ-forming hydrogels via i.t. injection for regional chemotherapy. Copyright © 2016. Published by Elsevier B.V.

A revised Pitzer model for low-temperature soluble salt assemblages at the Phoenix site, Mars

NASA Astrophysics Data System (ADS)

Toner, J. D.; Catling, D. C.; Light, B.

2015-10-01

The Wet Chemistry Laboratory (WCL) on the Mars Phoenix Lander measured ions in a soil-water extraction and found Na+, K+, H+ (pH), Ca2+, Mg2+, SO42-, ClO4-, and Cl-. Equilibrium models offer insights into salt phases that were originally present in the Phoenix soil, which dissolved to form the measured WCL solution; however, there are few experimental datasets for single cation perchlorates (ClO4-), and none for mixed perchlorates, at low temperatures, which are needed to build models. In this study, we measure ice and salt solubilities in binary and ternary solutions in the Na-Ca-Mg-ClO4 system, and then use this data, along with existing data, to construct a low-temperature Pitzer model for perchlorate brines. We then apply our model to a nominal WCL solution. Previous studies have modeled either freezing of a WCL solution or evaporation at a single temperature. For the first time, we model evaporation at subzero temperatures, which is relevant for dehydration conditions that might occur at the Phoenix site. Our model indicates that a freezing WCL solution will form ice, KClO4, hydromagnesite (3MgCO3·Mg(OH)2·3H2O), calcite (CaCO3), meridianiite (MgSO4·11H2O), MgCl2·12H2O, NaClO4·2H2O, and Mg(ClO4)2·6H2O at the eutectic (209 K). The total water held in hydrated salt phases at the eutectic is ∼1.2 wt.%, which is much greater than hydrated water contents when evaporation is modeled at 298.15 K (∼0.3 wt.%). Evaporation of WCL solutions at lower temperatures (down to 210 K) results in lower water activities and the formation of more dehydrated minerals, e.g. kieserite (MgSO4·H2O) instead of meridianiite. Potentially habitable brines, with water activity aw > 0.6, can occur when soil temperatures are above 220 K and when the soil liquid water content is greater than 0.4 wt.% (100 ×gH2O gsoil-1). In general, modeling indicates that mineral assemblages derived from WCL-type solutions are characteristic of the soil temperature, water content, and water activity conditions under which they formed, and are useful indicators of past environmental conditions.

Development of new UV-vis spectroscopic microwave-assisted method for determination of glucose in pharmaceutical samples

NASA Astrophysics Data System (ADS)

Mabood, Fazal; Hussain, Z.; Haq, H.; Arian, M. B.; Boqué, R.; Khan, K. M.; Hussain, K.; Jabeen, F.; Hussain, J.; Ahmed, M.; Alharasi, A.; Naureen, Z.; Hussain, H.; Khan, A.; Perveen, S.

2016-01-01

A new UV-Visible spectroscopic method assisted with microwave for the determination of glucose in pharmaceutical formulations was developed. In this study glucose solutions were oxidized by ammonium molybdate in the presence of microwave energy and reacted with aniline to produce a colored solution. Optimum conditions of the reaction including wavelength, temperature, and pH of the medium and relative concentration ratio of the reactants were investigated. It was found that the optimal wavelength for the reaction is 610 nm, the optimal reaction time is 80 s, the optimal reaction temperature is 160 °C, the optimal reaction pH is 4, and the optimal concentration ratio aniline/ammonium molybdate solution was found to be 1:1. The limits of detection and quantification of the method are 0.82 and 2.75 ppm for glucose solution, respectively. The use of microwaves improved the speed of the method while the use of aniline improved the sensitivity of the method by shifting the wavelength.

Elevated temperature strain gages

NASA Technical Reports Server (NTRS)

Brittain, J. O.; Geslin, D.; Lei, J. F.

1986-01-01

One of the goals of the HOST Program is the development of electrical resistance strain gages for static strain measurements at temperatures equal to or greater than 1273 K. Strain gage materials must have a reproducible or predictable response to temperature, time and strain. It is the objective of this research to investigate criteria for the selection of materials for such applications through electrical properties studies. The results of the investigation of two groups of materials, refractory compounds and binary alloy solid solutions are presented.

The Effects of Heat Treatment and Microstructure Variations on Disk Superalloy Properties at High Temperature

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Gayda, John; Telesman, Jack; Garg, Anita

2008-01-01

The effects of heat treatment and resulting microstructure variations on high temperature mechanical properties were assessed for a powder metallurgy disk superalloy LSHR. Blanks were consistently supersolvus solution heat treated and quenched at two cooling rates, than aged at varying temperatures and times. Tensile, creep, and dwell fatigue crack growth tests were then performed at 704 C. Gamma' precipitate microstructures were quantified. Relationships between heat treatment-microstructure, heat treatment-mechanical properties, and microstructure-mechanical properties were assessed.

Tensile Properties of Poly (N-vinyl caprolactam) Gels

NASA Technical Reports Server (NTRS)

Morgret, Leslie D.; Hinkley, Jeffrey A.

2004-01-01

N-vinyl caprolactam was copolymerized with ethylene glycol dimethacrylate using a free-radical initiator in alcohol/water solution. The resulting gels were thermally-responsive in water, undergoing an approximate fivefold reversible volume shrinkage between room temperature and ca. 50 C. Tensile testing showed that the stress-strain behavior was qualitatively different in the collapsed state above the temperature-induced transition. At the higher temperature, gels were stiffer, more ductile, and showed greater time dependence. Implications for the design of gel actuators are briefly discussed.

Microstructural Evolution and Mechanical Behavior of High Temperature Solders: Effects of High Temperature Aging

NASA Astrophysics Data System (ADS)

Hasnine, M.; Tolla, B.; Vahora, N.

2018-04-01

This paper explores the effects of aging on the mechanical behavior, microstructure evolution and IMC formation on different surface finishes of two high temperature solders, Sn-5 wt.% Ag and Sn-5 wt.% Sb. High temperature aging showed significant degradation of Sn-5 wt.% Ag solder hardness (34%) while aging has little effect on Sn-5 wt.% Sb solder. Sn-5 wt.% Ag experienced rapid grain growth as well as the coarsening of particles during aging. Sn-5 wt.% Sb showed a stable microstructure due to solid solution strengthening and the stable nature of SnSb precipitates. The increase of intermetallic compound (IMC) thickness during aging follows a parabolic relationship with time. Regression analysis (time exponent, n) indicated that IMC growth kinetics is controlled by a diffusion mechanism. The results have important implications in the selection of high temperature solders used in high temperature applications.

Development of apple chips technology

NASA Astrophysics Data System (ADS)

Kowalska, Hanna; Marzec, Agata; Kowalska, Jolanta; Samborska, Kinga; Tywonek, Małgorzata; Lenart, Andrzej

2018-05-01

For develop of apple chips technology without chemical preservation osmotic dehydration in cherry or apple juice concentrates or fructooligosaccharide solutions and convection drying were used. Studies included the effect of dehydration on the mass transfer in apples and the quality of the final product. The temperature, type of osmotic solution and its concentration were changeable. The fruit were tested on mass transfer indicators, stability (water activity), texture (breaking test) and nutritional value (polyphenol content, acidity). Sensory evaluation was also performed. On this basis, the verification of all options was made and the most acceptable samples were selected. Concentration of osmotic solutions at 25°Brix limited solids gain in apples. Under these conditions, the phenomenon of osmosis caused 8-10 times greater water loss than solids gain. Increasing the concentration of solutions up to 50°Brix had a significantly greater impact on mass exchange in apples, compared to increasing the temperature from 40 to 60 °C. Osmotic dehydration before drying did not significantly affect the water activity but increase of the temperature negatively affected on breaking force of the chips. Chips obtained by osmotic dehydration of apples in a cherry concentrate solution contained significantly more polyphenols, and were characterized by a higher acidity than the variants obtained by dehydration in concentrated apple juice. Furthermore, they were marked by red color which has been thought as part of the attractiveness of the product. The least sensory acceptable chips were prepared using osmotic pre-treatment in cherry concentrated juice solution with the addition of fructooligosaccharide.

Low-Temperature Photochemically Activated Amorphous Indium-Gallium-Zinc Oxide for Highly Stable Room-Temperature Gas Sensors.

PubMed

Jaisutti, Rawat; Kim, Jaeyoung; Park, Sung Kyu; Kim, Yong-Hoon

2016-08-10

We report on highly stable amorphous indium-gallium-zinc oxide (IGZO) gas sensors for ultraviolet (UV)-activated room-temperature detection of volatile organic compounds (VOCs). The IGZO sensors fabricated by a low-temperature photochemical activation process and exhibiting two orders higher photocurrent compared to conventional zinc oxide sensors, allowed high gas sensitivity against various VOCs even at room temperature. From a systematic analysis, it was found that by increasing the UV intensity, the gas sensitivity, response time, and recovery behavior of an IGZO sensor were strongly enhanced. In particular, under an UV intensity of 30 mW cm(-2), the IGZO sensor exhibited gas sensitivity, response time and recovery time of 37%, 37 and 53 s, respectively, against 750 ppm concentration of acetone gas. Moreover, the IGZO gas sensor had an excellent long-term stability showing around 6% variation in gas sensitivity over 70 days. These results strongly support a conclusion that a low-temperature solution-processed amorphous IGZO film can serve as a good candidate for room-temperature VOCs sensors for emerging wearable electronics.

Modeling of mid-infrared quantum cascade lasers: The role of temperature and operating field strength on the laser performance

NASA Astrophysics Data System (ADS)

Yousefvand, Hossein Reza

2017-07-01

In this paper a self-consistent numerical approach to study the temperature and bias dependent characteristics of mid-infrared (mid-IR) quantum cascade lasers (QCLs) is presented which integrates a number of quantum mechanical models. The field-dependent laser parameters including the nonradiative scattering times, the detuning and energy levels, the escape activation energy, the backfilling excitation energy and dipole moment of the optical transition are calculated for a wide range of applied electric fields by a self-consistent solution of Schrodinger-Poisson equations. A detailed analysis of performance of the obtained structure is carried out within a self-consistent solution of the subband population rate equations coupled with carrier coherent transport equations through the sequential resonant tunneling, by taking into account the temperature and bias dependency of the relevant parameters. Furthermore, the heat transfer equation is included in order to calculate the carrier temperature inside the active region levels. This leads to a compact predictive model to analyze the temperature and electric field dependent characteristics of the mid-IR QCLs such as the light-current (L-I), electric field-current (F-I) and core temperature-electric field (T-F) curves. For a typical mid-IR QCL, a good agreement was found between the simulated temperature-dependent L-I characteristic and experimental data, which confirms validity of the model. It is found that the main characteristics of the device such as output power and turn-on delay time are degraded by interplay between the temperature and Stark effects.

To the theory of non-local non-isothermal filtration in porous medium

NASA Astrophysics Data System (ADS)

Meilanov, R. R.; Akhmedov, E. N.; Beybalaev, V. D.; Magomedov, R. A.; Ragimkhanov, G. B.; Aliverdiev, A. A.

2018-01-01

A new approach to the theory of non-local and non-isothermal filtration based on the mathematical apparatus of fractional order derivatives is developing. A solution of the Cauchy problem for the system of equations of non-local non-isothermal filtration in fractional calculus is obtained. Some applications of the solutions obtained to the problems of underground hydrodynamics (fracturing and explosion) are considered. A computational experiment was carried out to analyze the solutions obtained. Graphs of pressure and temperature dependences are plotted against time.

Deformation behavior of a 16-8-2 GTA weld as influenced by its solidification substructure

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

Foulds, J.R.; Moteff, J.; Sikka, V.K.

1983-07-01

Weldment sections from formed and welded type 316 stainless steel pipe are characterized with respect to some time-independent (tensile) and time-dependent (creep) mechanical properties at temperatures between 25/sup 0/C and 649/sup 0/C. The GTA weldment, welded with 16-8-2 filler metal, is sectioned from pipe in the formed + welded + solution annealed + straightened condition, as well as in the same condition with an additional re-solution treatment. Detailed room temperature microhardness measurements on these sections before and after reannealing enable a determination of the different recovery characteristics of weld and base metal. The observed stable weld metal solidification dislocation substructuremore » in comparison with the base metal random dislocation structure, in fact, adequately explains weld/base metal elevated temperature mechanical behavior differences from this recovery characteristic standpoint. The weld metal substructure is the only parameter common to the variety of austenitic stainless steel welds exhibiting the consistent parent/weld metal deformation behavior differences described. As such, it must be considered the key to understanding weldment mechanical behavior.« less

Method of solution preparation of polyolefin class polymers for electrospinning processing included

NASA Technical Reports Server (NTRS)

Rabolt, John F. (Inventor); Givens, Steven R. (Inventor); Lee, Keun-Hyung (Inventor)

2011-01-01

A process to make a polyolefin fiber which has the following steps: mixing at least one polyolefin into a solution at room temperature or a slightly elevated temperature to form a polymer solution and electrospinning at room temperature said polymer solution to form a fiber.

Localization of toroidal motion and shear heating in 3-D high Rayleigh number convection with temperature-dependent viscosity

NASA Technical Reports Server (NTRS)

Balachandar, S.; Yuen, D. A.; Reuteler, D. M.

1995-01-01

We have applied spectral-transform methods to study three-dimensional thermal convection with temperature-dependent viscosity. The viscosity varies exponentially with the form exp(-BT), where B controls the viscosity contrast and T is temperature. Solutions for high Rayleigh numbers, up to an effective Ra of 6.25 x 10(exp 6), have been obtained for an aspect-ratio of 5x5x1 and a viscosity contrast of 25. Solutions show the localization of toroidal velocity fields with increasing vigor of convection to a coherent network of shear-zones. Viscous dissipation increases with Rayleigh number and is particularly strong in regions of convergent flows and shear deformation. A time-varying depth-dependent mean-flow is generated because of the correlation between laterally varying viscosity and velocity gradients.

Chip Scale Ultra-Stable Clocks: Miniaturized Phonon Trap Timing Units for PNT of CubeSats

NASA Technical Reports Server (NTRS)

Rais-Zadeh, Mina; Altunc, Serhat; Hunter, Roger C.; Petro, Andrew

2016-01-01

The Chip Scale Ultra-Stable Clocks (CSUSC) project aims to provide a superior alternative to current solutions for low size, weight, and power timing devices. Currently available quartz-based clocks have problems adjusting to the high temperature and extreme acceleration found in space applications, especially when scaled down to match small spacecraft size, weight, and power requirements. The CSUSC project aims to utilize dual-mode resonators on an ovenized platform to achieve the exceptional temperature stability required for these systems. The dual-mode architecture utilizes a temperature sensitive and temperature stable mode simultaneously driven on the same device volume to eliminate ovenization error while maintaining extremely high performance. Using this technology it is possible to achieve parts-per-billion (ppb) levels of temperature stability with multiple orders of magnitude smaller size, weight, and power.

Conditions and mechanisms for the formation of nano-sized Delafossite (CuFeO{sub 2}) at temperatures ≤90 °C in aqueous solution

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

John, Melanie, E-mail: melanie.john@min.uni-muenchen.de; Heuss-Aßbichler, Soraya; Ullrich, Aladin

In this study, we present the mechanism of CuFeO{sub 2} formation in aqueous solution at low temperatures ≤90 °C, using sulfate salts as reactants. Furthermore, we demonstrate the influence of experimental conditions (alkalization, reaction and ageing temperature and time) on the synthesized nanoparticles. In all cases, GR–SO{sub 4}, a Fe(II–III) layered double hydroxysulphate (Fe{sup 2+}{sub 4}Fe{sup 3+}{sub 2}(OH){sub 12}·SO{sub 4}) and Cu{sub 2}O precipitate first. During further OH{sup −} supply GR–SO{sub 4} oxidizes and forms Fe{sub 10}O{sub 14}(OH){sub 2}, Cu{sub 2}O and CuFeO{sub 2} crystals. Due to the high pH further CuFeO{sub 2} crystals grow at the cost of themore » unstable intermediate products. The reaction rate increases with increasing ageing temperature, reaction pH and, in particular, NaOH concentrations in the solution. As a result, highly crystalline CuFeO{sub 2} (3R and 2H polytypes) nanoparticles showing hexagonal morphology can be synthesized at 70 °C within 10 h or at 50 °C within 1 week. The formation of 2H polytype is favored by additional OH{sup −} supply during the pH-stat time and rather low temperatures. - Highlights: • We solve the formation mechanism of pure CuFeO{sub 2} using sulfates as reactants. • CuFeO{sub 2} nanoparticles crystallize on cost of green rust, Fe{sub 10}O{sub 14}(OH){sub 2} and Cu{sub 2}O. • The reaction rate increases with increasing temperature and OH- concentration. • CuFeO{sub 2} nanoparticles form at 50 °C within one week and at 70 °C within 10 h. • 2H-polytype of CuFeO{sub 2} is favored by additional NaOH supply during pH-stat-time.« less

Zr/ZrO2 sensors for in situ measurement of pH in high-temperature and -pressure aqueous solutions.

PubMed

Zhang, R H; Zhang, X T; Hu, S M

2008-04-15

The aim of this study is to develop new pH sensors that can be used to test and monitor hydrogen ion activity in hydrothermal conditions. A Zr/ZrO2 oxidation electrode is fabricated for in situ pH measurement of high-temperature aqueous solutions. This sensor responds rapidly and precisely to pH over a wide range of temperature and pressure. The Zr/ZrO2 electrode was made by oxidizing zirconium metal wire with Na2CO3 melt, which produced a thin film of ZrO2 on its surface. Thus, an oxidation-reduction electrode was produced. The Zr/ZrO2 electrode has a good electrochemical stability over a wide range of pH in high-temperature aqueous solutions when used with a Ag/AgCl reference electrode. Measurements of the Zr/ZrO2 sensor potential against a Ag/AgCl reference electrode is shown to vary linearly with pH between temperatures 20 and 200 degrees C. The slope of the potential versus pH at high temperature is slightly below the theoretical value indicated by the Nernst equation; such deviation is attributed to the fact that the sensor is not strictly at equilibrium with the solution to be tested in a short period of time. The Zr/ZrO2 sensor can be calibrated over the conditions that exist in the natural deep-seawater. Our studies showed that the Zr/ZrO2 electrode is a suitable pH sensor for the hydrothermal systems at midocean ridge or other geothermal systems with the high-temperature environment. Yttria-stabilized zirconia sensors have also been used to investigate the pH of hydrothermal fluids in hot springs vents at midocean ridge. These sensors, however, are not sensitive below 200 degrees C. Zr/ZrO2 sensors have wider temperature range and can be severed as good alternative sensors for measuring the pH of hydrothermal fluids.

The classical D-type expansion of spherical H II regions

NASA Astrophysics Data System (ADS)

Williams, Robin J. R.; Bibas, Thomas G.; Haworth, Thomas J.; Mackey, Jonathan

2018-06-01

Recent numerical and analytic work has highlighted some shortcomings in our understanding of the dynamics of H II region expansion, especially at late times, when the H II region approaches pressure equilibrium with the ambient medium. Here we reconsider the idealized case of a constant radiation source in a uniform and spherically symmetric ambient medium, with an isothermal equation of state. A thick-shell solution is developed which captures the stalling of the ionization front and the decay of the leading shock to a weak compression wave as it escapes to large radii. An acoustic approximation is introduced to capture the late-time damped oscillations of the H II region about the stagnation radius. Putting these together, a matched asymptotic equation is derived for the radius of the ionization front which accounts for both the inertia of the expanding shell and the finite temperature of the ambient medium. The solution to this equation is shown to agree very well with the numerical solution at all times, and is superior to all previously published solutions. The matched asymptotic solution can also accurately model the variation of H II region radius for a time-varying radiation source.

Pretreatment of corn straw using the alkaline solution of ionic liquids.

PubMed

Liu, Zhen; Li, Longfei; Liu, Cheng; Xu, Airong

2018-07-01

In the present work, the pretreatment of corn stalk with the solution of 1-ethyl-3-methylimidazolium acetate ([Emim]Ac) ionic liquid containing NaOH was explored for its lignin removal. The effects of reaction temperature, reaction time, and solid-liquid ratio on the lignin removal efficiency were determined by the response surface methodology (RSM). The pretreatment conditions were optimized by the Box-Behnken design and the comparative study of the composition and structure of corn straw before and after the pretreatment to be: reaction temperature 98.5 °C, reaction time 1.31 h, and solid-liquid ratio 1:8.7. Under the optimized conditions, the cellulose and hemicellulose contents of the corn straw were increased to 85.69% and 9.1%, respectively, and the lignin content was reduced to 2.27% with the lignin removal efficiency up to 87.4%. Copyright © 2018 Elsevier Ltd. All rights reserved.

Dissolution and Separation of Aluminum and Aluminosilicates

DOE PAGES

McFarlane, Joanna; Benker, Dennis; DePaoli, David W.; ...

2015-12-19

The selection of an aluminum alloy for target irradiation affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the dissolver, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. Aluminosilicate dissolution presents challenges in a number of different areas, metals extraction from minerals, flyash treatment, and separations from aluminum alloys. We present experimental work that attempts to maximize dissolution of aluminum metal, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as amore » function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. Our data have been compared with published calculations of aluminum phase diagrams. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.« less

Exponential bound in the quest for absolute zero

NASA Astrophysics Data System (ADS)

Stefanatos, Dionisis

2017-10-01

In most studies for the quantification of the third law of thermodynamics, the minimum temperature which can be achieved with a long but finite-time process scales as a negative power of the process duration. In this article, we use our recent complete solution for the optimal control problem of the quantum parametric oscillator to show that the minimum temperature which can be obtained in this system scales exponentially with the available time. The present work is expected to motivate further research in the active quest for absolute zero.

Exponential bound in the quest for absolute zero.

PubMed

Stefanatos, Dionisis

2017-10-01

In most studies for the quantification of the third law of thermodynamics, the minimum temperature which can be achieved with a long but finite-time process scales as a negative power of the process duration. In this article, we use our recent complete solution for the optimal control problem of the quantum parametric oscillator to show that the minimum temperature which can be obtained in this system scales exponentially with the available time. The present work is expected to motivate further research in the active quest for absolute zero.

Surface treatment process of Al-Mg alloy powder by BTSPS

NASA Astrophysics Data System (ADS)

Zhao, Ran; Gao, Xinbao; Lu, Yanling; Du, Fengzhen; Zhang, Li; Liu, Dazhi; Chen, Xuefang

2018-04-01

The surface of Al-Mg alloy powder was treated by BTSPS(bis(triethoxysilylpropyl)tetrasulfide) in order to avoid easy oxidation in air. The pH value, reaction temperature, reaction time, and reaction concentration were used as test conditions. The results show that the BTSPS can form a protected film on the surface of Al-Mg alloy powder. Select the best test solution by orthogonal test. The study found that the reaction time and reaction temperature have the biggest influence on the two indexes of the orthogonal test (melting enthalpy of heat and enthalpy of oxidation). The optimal conditions were as follows: pH value is 8, reaction concentration is 2%, reaction temperature is 25 °C, reaction time is 2 h. The oxidation weight gain of the alloy reached 74.45% and the decomposition temperature of silane film is 181.8 °C.

Convective flows of generalized time-nonlocal nanofluids through a vertical rectangular channel

NASA Astrophysics Data System (ADS)

Ahmed, Najma; Vieru, Dumitru; Fetecau, Constantin; Shah, Nehad Ali

2018-05-01

Time-nonlocal generalized model of the natural convection heat transfer and nanofluid flows through a rectangular vertical channel with wall conditions of the Robin type are studied. The generalized mathematical model with time-nonlocality is developed by considering the fractional constitutive equations for the shear stress and thermal flux defined with the time-fractional Caputo derivative. The Caputo power-law non-local kernel provides the damping to the velocity and temperature gradient; therefore, transport processes are influenced by the histories at all past and present times. Analytical solutions for dimensionless velocity and temperature fields are obtained by using the Laplace transform coupled with the finite sine-cosine Fourier transform which is suitable to problems with boundary conditions of the Robin type. Particularizing the fractional thermal and velocity parameters, solutions for three simplified models are obtained (classical linear momentum equation with damped thermal flux; fractional shear stress constitutive equation with classical Fourier's law for thermal flux; classical shear stress and thermal flux constitutive equations). It is found that the thermal histories strongly influence the thermal transport for small values of time t. Also, the thermal transport can be enhanced if the thermal fractional parameter decreases or by increasing the nanoparticles' volume fraction. The velocity field is influenced on the one hand by the temperature of the fluid and on the other by the damping of the velocity gradient introduced by the fractional derivative. Also, the transport motions of the channel walls influence the motion of the fluid layers located near them.

Effect of temperature, viscosity and surface tension on gelatine structures produced by modified 3D printer

NASA Astrophysics Data System (ADS)

Kalkandelen, C.; Ozbek, B.; Ergul, N. M.; Akyol, S.; Moukbil, Y.; Oktar, F. N.; Ekren, N.; Kılıc, O.; Kılıc, B.; Gunduz, O.

2017-12-01

In the present study, gelatine scaffolds were manufactured by using modified 3D (3 Dimensional) printing machine and the effect of different parameters on scaffold structure were investigated. Such as; temperature, viscosity and surface tension of the gelatine solutions. The varying of gelatine solutions (1, 3, 5, 10, 15 and 20 wt.%) were prepared and characterized. It has been detected that, viscosity of those solutions were highly influenced by temperature and gelatine concentration. Specific CAD (Computer Assistant Design) model which has 67% porosity and original design were created via computer software. However, at high temperatures gelatine solutions caused like liquid but at the lower temperatures were observed the opposite behaviour. In addition to that, viscosity of 1,3,5 wt.% solutions were not enough to build a structure and 20 wt.% gelatine solution too hard to handle, because of the sudden viscosity changes with temperature. Even though, scaffold of the 20 wt.% gelatine solution printed hardly but it was observed the best printed solutions, which were 10 and 15 wt.% gelatine solutions. As a result, 3D printing of gelatine were found the values of the best temperature, viscosity, surface tension and gelatine concentration such as 25-35 °C, 36-163 cP, 46-59 mN/m and 15 wt.% gelatine concentration respectively.

Effect of depletion rate on solution gas drive in shale

NASA Astrophysics Data System (ADS)

Zhang, Mingshan; Sang, Qian; Gong, Houjian; Li, Yajun; Dong, Mingzhe

2018-01-01

Solution gas drive process has been studied extensively in sand rocks and heavy oil reservoirs for a long time. Oil recovery is affected by several factors, such as depletion rate, initial GOR (gas oil ratio), oil viscosity, and temperature and so on. Before the solution gas drive tests, elastic drive without dissolved gas was carried out as a reference, which shows a limited oil recovery. Solution gas drive experiments were conducted in shale to study oil recovery with various depletion rates. Results show that oil recovery increases with the decrease of depletion rates because of the low permeability and desorption of methane.

Heat-induced morphological transformation of gold nanodumbbells in ionic surfactant solutions

NASA Astrophysics Data System (ADS)

Wen, Ting-Chun; Lu, Chung-Wen; Hsieh, Wei-Chi; Chang, Sheng-Te; Yang, Ya-Ting; Deng, Jin-Pei

2018-01-01

The thermal stability of gold nanodumbbells (NDs) is studied in aqueous solution of ionic surfactants. It is found in aqueous solution of cetyltrimethylammonium bromide that the blue-shift of longitudinal surface plasmon resonance band of gold NDs occurs at 75 °C and the new gold nanorods (NRs) with shortened aspect ratio are formed at the same time. The aspect ratio of the generated gold NRs gradually decreases and finally approaches ∼1.7 after repeated processing. Similarly, the same results are also obtained in aqueous solution of sodium dodecyl sulfate at room temperature. Mechanism is proposed for the shape transformation of gold NDs.

Application of troposphere model from NWP and GNSS data into real-time precise positioning

NASA Astrophysics Data System (ADS)

Wilgan, Karina; Hadas, Tomasz; Kazmierski, Kamil; Rohm, Witold; Bosy, Jaroslaw

2016-04-01

The tropospheric delay empirical models are usually functions of meteorological parameters (temperature, pressure and humidity). The application of standard atmosphere parameters or global models, such as GPT (global pressure/temperature) model or UNB3 (University of New Brunswick, version 3) model, may not be sufficient, especially for positioning in non-standard weather conditions. The possible solution is to use regional troposphere models based on real-time or near-real time measurements. We implement a regional troposphere model into the PPP (Precise Point Positioning) software GNSS-WARP (Wroclaw Algorithms for Real-time Positioning) developed at Wroclaw University of Environmental and Life Sciences. The software is capable of processing static and kinematic multi-GNSS data in real-time and post-processing mode and takes advantage of final IGS (International GNSS Service) products as well as IGS RTS (Real-Time Service) products. A shortcoming of PPP technique is the time required for the solution to converge. One of the reasons is the high correlation among the estimated parameters: troposphere delay, receiver clock offset and receiver height. To efficiently decorrelate these parameters, a significant change in satellite geometry is required. Alternative solution is to introduce the external high-quality regional troposphere delay model to constrain troposphere estimates. The proposed model consists of zenith total delays (ZTD) and mapping functions calculated from meteorological parameters from Numerical Weather Prediction model WRF (Weather Research and Forecasting) and ZTDs from ground-based GNSS stations using the least-squares collocation software COMEDIE (Collocation of Meteorological Data for Interpretation and Estimation of Tropospheric Pathdelays) developed at ETH Zurich.

Nonuniformity correction based on focal plane array temperature in uncooled long-wave infrared cameras without a shutter.

PubMed

Liang, Kun; Yang, Cailan; Peng, Li; Zhou, Bo

2017-02-01

In uncooled long-wave IR camera systems, the temperature of a focal plane array (FPA) is variable along with the environmental temperature as well as the operating time. The spatial nonuniformity of the FPA, which is partly affected by the FPA temperature, obviously changes as well, resulting in reduced image quality. This study presents a real-time nonuniformity correction algorithm based on FPA temperature to compensate for nonuniformity caused by FPA temperature fluctuation. First, gain coefficients are calculated using a two-point correction technique. Then offset parameters at different FPA temperatures are obtained and stored in tables. When the camera operates, the offset tables are called to update the current offset parameters via a temperature-dependent interpolation. Finally, the gain coefficients and offset parameters are used to correct the output of the IR camera in real time. The proposed algorithm is evaluated and compared with two representative shutterless algorithms [minimizing the sum of the squares of errors algorithm (MSSE), template-based solution algorithm (TBS)] using IR images captured by a 384×288 pixel uncooled IR camera with a 17 μm pitch. Experimental results show that this method can quickly trace the response drift of the detector units when the FPA temperature changes. The quality of the proposed algorithm is as good as MSSE, while the processing time is as short as TBS, which means the proposed algorithm is good for real-time control and at the same time has a high correction effect.

Molecular Interactions in 1,4-Dioxane, Tetrahydrofuran, and Ethyl Acetate Solutions of 1,1'-Bis(4-isopropyloxyacetylphenoxy)cyclohexane on Reological, Density, and Acoustic Behavior

NASA Astrophysics Data System (ADS)

Dhaduk, B. B.; Patel, Ch. B.; Parsania, P. H.

2017-12-01

Various thermo-acoustical parameters of 1,4-dioxane, tetrahydofuran and ethylacetae solutions of 1,1'-bis(4-isopropyloxyacetylphenoxy)cyclohexane were determined at different temperatures using density, viscosity and ultrasonic speed and correlated with concentration. Linear increase of ultrasonic speed, specific acoustical impedance, Rao's molar sound function, Van der Waals constant and free volume with concentration C and decreased with temperature. Linear decrease of adiabatic compressibility, internal pressure, intermolecular free path length, classical absorption coefficient, and viscous relaxation time with concentration and increased with temperature indicated existence of strong molecular interactions in solutions and further supported by positive values of solvation number. Gibbs free energy of activation decreased with C in all three systems. It is decreased with T in 1,4-dioxane, while increased in tetrahydrofuran and ethyl acetate. Both enthalpy of activation and entropy of activation are increased gradually with C in 1,4-dioxane, while they are negative and remained practically independent of concentration in 1,4-dioxane and tetrahydofuran systems.

Studies on the controllable transformation of ferrihydrite

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

Liu Hui, E-mail: liuhuicn@126.co; Ma, Miaorui; Qin, Mei

2010-09-15

Ferrihydrite was prepared by two different procedures. Ferrihydrite-1 was prepared by dropping NaOH solution into Fe(III) solution. Ferrihydrite-2 was prepared by adding Fe(III) and NaOH solutions into a certain volume of water simultaneously. Our earlier results obtained at {approx}100 {sup o}C have shown that the structure of ferrihydrite-2 favors its solid state transformation mechanism. Further research reveals that the structure of ferrihydrite-2 favors its dissolution re-crystallization mechanism at a temperature of {<=}60 {sup o}C. Based on the transformation mechanism of ferrihydrite at different temperatures, the controllable transformation from ferrihydrite to various iron (hydr)oxides such as lepidocrocite, goethite, hematite and magnetitemore » can be achieved by adjusting the pH, transformation temperature, transformation time, the amount of Fe(II) as well as the preparation procedures of ferrihydrite. The results in the present paper give a nice example that the transformation of a precursor can be controlled with the help of mechanism. - Graphical abstract: The transformations from ferrihydrite to lepidocrocite, goethite, hematite or magnetite can be controlled with the help of mechanism.« less

Free oscillations in a climate model with ice-sheet dynamics

NASA Technical Reports Server (NTRS)

Kallen, E.; Crafoord, C.; Ghil, M.

1979-01-01

A study of stable periodic solutions to a simple nonlinear model of the ocean-atmosphere-ice system is presented. The model has two dependent variables: ocean-atmosphere temperature and latitudinal extent of the ice cover. No explicit dependence on latitude is considered in the model. Hence all variables depend only on time and the model consists of a coupled set of nonlinear ordinary differential equations. The globally averaged ocean-atmosphere temperature in the model is governed by the radiation balance. The reflectivity to incoming solar radiation, i.e., the planetary albedo, includes separate contributions from sea ice and from continental ice sheets. The major physical mechanisms active in the model are (1) albedo-temperature feedback, (2) continental ice-sheet dynamics and (3) precipitation-rate variations. The model has three-equilibrium solutions, two of which are linearly unstable, while one is linearly stable. For some choices of parameters, the stability picture changes and sustained, finite-amplitude oscillations obtain around the previously stable equilibrium solution. The physical interpretation of these oscillations points to the possibility of internal mechanisms playing a role in glaciation cycles.

Removal of acid blue 062 on aqueous solution using calcinated colemanite ore waste.

PubMed

Atar, Necip; Olgun, Asim

2007-07-19

Colemanite ore waste (CW) has been employed as adsorbent for the removal of acid blue 062 anionic dye (AB 062) from aqueous solution. The adsorption of AB 062 onto CW was examined with respect to contact time, calcination temperature, particle size, pH, adsorbent dosage and temperature. The physical and chemical properties of the CW, such as particle sizes and calcinations temperature, play important roles in dye adsorption. The dye adsorption largely depends on the initial pH of the solution with maximum uptake occurring at pH 1. Three simplified kinetics models, namely, pseudo-first order, pseudo-second order, and intraparticle diffusion models were tested to investigate the adsorption mechanisms. The kinetic adsorption of AB 062 on CW follows a pseudo-second order equation. The adsorption data have been analyzed using Langmuir and Freundlich isotherms. The results indicate that the Langmuir model provides the best correlation of the experimental data. Isotherms have also been used to obtain the thermodynamic parameters such as free energy, enthalpy and entropy of the adsorption of dye onto CW.

Fundamental Effects of Aging on Creep Properties of Solution-Treated Low-Carbon N-155 Alloy

NASA Technical Reports Server (NTRS)

Frey, D N; Freeman, J W; White, A E

1950-01-01

A method is developed whereby the fundamental mechanisms are investigated by which processing, heat treatment, and chemical composition control the properties of alloys at high temperatures. The method used metallographic examination -- both optical and electronic --studies of x-ray diffraction-line widths, intensities, and lattice parameters, and hardness surveys to evaluate fundamental structural conditions. Mechanical properties at high temperatures are then measured and correlated with these measured structural conditions. In accordance with this method, a study was made of the fundamental mechanism by which aging controlled the short-time creep and rupture properties of solution-treated low-carbon n-155 alloy at 1200 degrees F.

Conditioning of carbonaceous material prior to physical beneficiation

DOEpatents

Warzinski, Robert P.; Ruether, John A.

1987-01-01

A carbonaceous material such as coal is conditioned by contact with a supercritical fluid prior to physical beneficiation. The solid feed material is contacted with an organic supercritical fluid such as cyclohexane or methanol at temperatures slightly above the critical temperature and pressures of 1 to 4 times the critical pressure. A minor solute fraction is extracted into critical phase and separated from the solid residuum. The residuum is then processed by physical separation such as by froth flotation or specific gravity separation to recover a substantial fraction thereof with reduced ash content. The solute in supercritical phase can be released by pressure reduction and recombined with the low-ash, carbonaceous material.

Rotational diffusion of nondipolar and charged solutes in alkyl-substituted imidazolium triflimides: effect of C2 methylation on solute rotation.

PubMed

Prabhu, Sugosh R; Dutt, G B

2014-08-07

Rotational diffusion of a nondipolar solute 2,5-dimethyl-1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DMDPP) and a charged solute rhodamine 110 (R110) has been investigated in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][Tf2N]) and 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide ([BMMIM][Tf2N]) to understand the influence of the C2 methylation on solute rotation. The measured reorientation times of the nondipolar solute DMDPP are similar in both the ionic liquids and follow Stokes-Einstein-Debye hydrodynamic theory with slip hydrodynamics. In contrast, rotational diffusion of the charged solute R110 in [BMIM][Tf2N] obeys stick hydrodynamics due to specific interactions with the anion of the ionic liquid. Nevertheless, the intriguing result of this study is that the reorientation times of R110 in [BMMIM][Tf2N] deviate significantly from the predictions of stick hydrodynamics, especially at ambient temperatures. The solute-solvent boundary condition parameter Cobs, which is defined as the ratio of the measured reorientation time to the one calculated using the SED theory with stick boundary condition, for R110 is lower by a factor of 2 in [BMMIM][Tf2N] compared to [BMIM][Tf2N] at 298 K. Upon increasing the temperature, Cobs gradually increases and eventually matches with that obtained in [BMIM][Tf2N] at 348 K. It has been well established that methylation of the C2 position in [BMMIM][Tf2N] switches off the main hydrogen-bonding interaction between the anion and the cation, but increases the Coulombic interactions. As a consequence of the enhanced interionic interactions between the cation and anion of the ionic liquid, specific interactions between R110 and [Tf2N] diminish leading to the faster rotation of the solute. However, such an influence is not apparent in case of DMDPP as it does not experience specific interactions with either the cation or the anion of these ionic liquids.

Matching-pursuit/split-operator-Fourier-transform computations of thermal correlation functions.

PubMed

Chen, Xin; Wu, Yinghua; Batista, Victor S

2005-02-08

A rigorous and practical methodology for evaluating thermal-equilibrium density matrices, finite-temperature time-dependent expectation values, and time-correlation functions is described. The method involves an extension of the matching-pursuit/split-operator-Fourier-transform method to the solution of the Bloch equation via imaginary-time propagation of the density matrix and the evaluation of Heisenberg time-evolution operators through real-time propagation in dynamically adaptive coherent-state representations.

Temperature dependent dielectric properties and ion transportation in solid polymer electrolyte for lithium ion batteries

NASA Astrophysics Data System (ADS)

Sengwa, R. J.; Dhatarwal, Priyanka; Choudhary, Shobhna

2016-05-01

Solid polymer electrolyte (SPE) film consisted of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) blend matrix with lithium tetrafluroborate (LiBF4) as dopant ionic salt and poly(ethylene glycol) (PEG) as plasticizer has been prepared by solution casting method followed by melt pressing. Dielectric properties and ionic conductivity of the SPE film at different temperatures have been determined by dielectric relaxation spectroscopy. It has been observed that the dc ionic conductivity of the SPE film increases with increase of temperature and also the decrease of relaxation time. The temperature dependent relaxation time and ionic conductivity values of the electrolyte are governed by the Arrhenius relation. Correlation observed between dc conductivity and relaxation time confirms that ion transportation occurs with polymer chain segmental dynamics through hopping mechanism. The room temperature ionic conductivity is found to be 4 × 10-6 S cm-1 which suggests the suitability of the SPE film for rechargeable lithium batteries.

Temperature dependent dielectric properties and ion transportation in solid polymer electrolyte for lithium ion batteries

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

Sengwa, R. J., E-mail: rjsengwa@rediffmail.com; Dhatarwal, Priyanka, E-mail: dhatarwalpriyanka@gmail.com; Choudhary, Shobhna, E-mail: shobhnachoudhary@rediffmail.com

2016-05-06

Solid polymer electrolyte (SPE) film consisted of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) blend matrix with lithium tetrafluroborate (LiBF{sub 4}) as dopant ionic salt and poly(ethylene glycol) (PEG) as plasticizer has been prepared by solution casting method followed by melt pressing. Dielectric properties and ionic conductivity of the SPE film at different temperatures have been determined by dielectric relaxation spectroscopy. It has been observed that the dc ionic conductivity of the SPE film increases with increase of temperature and also the decrease of relaxation time. The temperature dependent relaxation time and ionic conductivity values of the electrolyte are governedmore » by the Arrhenius relation. Correlation observed between dc conductivity and relaxation time confirms that ion transportation occurs with polymer chain segmental dynamics through hopping mechanism. The room temperature ionic conductivity is found to be 4 × 10{sup −6} S cm{sup −1} which suggests the suitability of the SPE film for rechargeable lithium batteries.« less

Method for single crystal growth of photovoltaic perovskite material and devices

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

Huang, Jinsong; Dong, Qingfeng

Systems and methods for perovskite single crystal growth include using a low temperature solution process that employs a temperature gradient in a perovskite solution in a container, also including at least one small perovskite single crystal, and a substrate in the solution upon which substrate a perovskite crystal nucleates and grows, in part due to the temperature gradient in the solution and in part due to a temperature gradient in the substrate. For example, a top portion of the substrate external to the solution may be cooled.

Numerical and Experimental Studies of the Natural Convection Flow Within a Horizontal Cylinder Subjected to a Uniformly Cold Wall Boundary Condition. Ph.D. Thesis - Va. Poly. Inst. and State Univ.

NASA Technical Reports Server (NTRS)

Stewart, R. B.

1972-01-01

Numberical solutions are obtained for the quasi-compressible Navier-Stokes equations governing the time dependent natural convection flow within a horizontal cylinder. The early time flow development and wall heat transfer is obtained after imposing a uniformly cold wall boundary condition on the cylinder. Solutions are also obtained for the case of a time varying cold wall boundary condition. Windware explicit differ-encing is used for the numerical solutions. The viscous truncation error associated with this scheme is controlled so that first order accuracy is maintained in time and space. The results encompass a range of Grashof numbers from 8.34 times 10,000 to 7 times 10 to the 7th power which is within the laminar flow regime for gravitationally driven fluid flows. Experiments within a small scale instrumented horizontal cylinder revealed the time development of the temperature distribution across the boundary layer and also the decay of wall heat transfer with time.

Speed of sound and acoustic attenuation of compounds affected during optoacoustic monitoring of thermal therapies measured in the temperature range from 5°C to 60°C

NASA Astrophysics Data System (ADS)

Oruganti, Tanmayi; Petrova, Elena; Oraevsky, Alexander A.; Ermilov, Sergey A.

2015-03-01

Optoacoustic (photoacoustic) imaging is being adopted for monitoring tissue temperature during hypothermic and hyperthermic cancer treatments. The technique's accuracy benefits from the knowledge of speed of sound (SoS) and acoustic coefficient of attenuation (AcA) as they change with temperature in biological tissues, blood, and acoustic lens of an ultrasound probe. In these studies we measured SoS and AcA of different ex vivo tissues and blood components (plasma and erythrocyte concentrates) in the temperature range from 5°C to 60°C. We used the technique based on measurements of time-delay and spectral amplitude of pressure pulses generated by wideband planar acoustic waves propagating through the interrogated medium. Water was used as a reference medium with known acoustic properties. In order to validate our experimental technique, we measured the temperature dependence of SoS and AcA for aqueous NaCl solution of known concentration and obtained the results in agreement with published data. Similar to NaCl solution and pure water, SoS in blood and plasma was monotonously increasing with temperature. However, SoS of erythrocyte concentrates displayed abnormalities at temperatures above 45°C, suggesting potential effects from hemoglobin denaturation and/or hemolysis of erythrocytes. On the contrary to aqueous solutions, the SoS in polyvinyl-chloride (plastisol) - a material frequently used for mimicking optical and acoustic properties of tissues - decreased with temperature. We also measured SoS and AcA in silicon material of an acoustic lens and did not observe temperature-related changes of SoS.

Well-posed two-temperature constitutive equations for stable dense fluid shock waves using molecular dynamics and generalizations of Navier-Stokes-Fourier continuum mechanics.

PubMed

Hoover, Wm G; Hoover, Carol G

2010-04-01

Guided by molecular dynamics simulations, we generalize the Navier-Stokes-Fourier constitutive equations and the continuum motion equations to include both transverse and longitudinal temperatures. To do so we partition the contributions of the heat transfer, the work done, and the heat flux vector between the longitudinal and transverse temperatures. With shockwave boundary conditions time-dependent solutions of these equations converge to give stationary shockwave profiles. The profiles include anisotropic temperature and can be fitted to molecular dynamics results, demonstrating the utility and simplicity of a two-temperature description of far-from-equilibrium states.

Joint inversion of shear wave travel time residuals and geoid and depth anomalies for long-wavelength variations in upper mantle temperature and composition along the Mid-Atlantic Ridge

NASA Technical Reports Server (NTRS)

Sheehan, Anne F.; Solomon, Sean C.

1991-01-01

Measurements were carried out for SS-S differential travel time residuals for nearly 500 paths crossing the northern Mid-Atlantic Ridge, assuming that the residuals are dominated by contributions from the upper mantle near the surface bounce point of the reflected phase SS. Results indicate that the SS-S travel time residuals decrease linearly with square root of age, to an age of 80-100 Ma, in general agreement with the plate cooling model. A joint inversion was formulated of travel time residuals and geoid and bathymetric anomalies for lateral variation in the upper mantle temperature and composition. The preferred inversion solutions were found to have variations in upper mantle temperature along the Mid-Atlantic Ridge of about 100 K. It was calculated that, for a constant bulk composition, such a temperature variation would produce about a 7-km variation in crustal thickness, larger than is generally observed.

Determination of aliphatic amines in mineral flotation liquors and reagents by high-performance liquid chromatography after derivatization with 4-chloro-7-nitrobenzofurazan.

PubMed

Hao, F; Lwin, T; Bruckard, W J; Woodcock, J T

2004-11-05

The method described here fulfils the need for a suitable analytical method to determine the concentrations of single and mixed aliphatic amines in the range from hexylamine (C6) to octadecylamine (C18) in flotation test solutions and in commercial flotation collectors. Amines do not have a UV-vis spectrum in aqueous solution but by reacting an amine-containing solution with 4-chloro-7-nitrobenzofurazan solution (chloro-NBD), derivatized products (amino-NBDs) are formed which have absorbance maxima at 470nm. Excess chloro-NBD and the amino-NBDs can be separated from each other by high-performance liquid chromatography (HPLC) and their concentrations measured with a UV-vis detector. Important variables in the derivatization stage are pH, temperature, chloro-NBD concentration, and reaction time, all of which interact with each other. A three-stage statistical procedure was used to determine the optimum conditions. In each stage, an 8-test design was used in which a high and low limit was set for each variable, and the chromatogram peak area of the derived amino-NBD was measured. The optimum derivatization conditions established were pH 8.9, chloro-NBD concentration 0.20% (w/v), temperature 70 degrees C, and reaction time 60 min. Optimum elution conditions for chromatography were an eluent containing 80% (v/v) acetonitrile in aqueous solution containing 40mM acetic acid at pH 4.5. With a flow rate of 2.0 ml/min, dodecylamine had a retention time of about 3 min, whereas octadecylamine had a retention time of 44 min. Straight-line calibration curves were obtained up to at least 200 ppm of amine in solution. The lower limit of detection was estimated to be 0.05 microM (10ppb) with a signal to noise ratio of 3. No interfering substances were found. The method was successfully applied to the analysis of solutions from an actual flotation test and to a solid commercial amine.

Stability studies of oxytetracycline in methanol solution

NASA Astrophysics Data System (ADS)

Wang, Wei; Wu, Nan; Yang, Jinghui; Zeng, Ming; Xu, Chenshan; Li, Lun; Zhang, Meng; Li, Liting

2018-02-01

As one kind of typical tetracycline antibiotics, antibiotic residues of oxytetracycline have been frequently detected in many environmental media. In this study, the stability of oxytetracycline in methanol solution was investigated by high-performance liquid chromatography combined with UV-vis (HPLC-UV). The results show that the stability of oxytetracycline in methanol solution is highly related to its initial concentration and the preserved temperature. Under low temperature condition, the solution was more stable than under room temperature preservation. Under the same temperature preservation condition, high concentrations of stock solutions are more stable than low concentrations. The study provides a foundation for preserving the oxytetracycline-methanol solution.

Thermosolutal Marangoni convection short-time regimes - Proposals for drop tower experiments and real time computer simulation

NASA Astrophysics Data System (ADS)

Polezhaev, V. I.; Ermakov, M. K.

1992-12-01

Results are presented of a parametrical study of flow patterns, heat transfer, and time scales of thermosolutal Marangoni convection in a cavity with temperature and solutal gradients along the free surface and adiabatic bottom for the case of zero gravity. Nusselt number, concentration difference across the cavity, and flow/temperature fields for the different regimes are presented; they show the possibility to use Drop Tower 'Bremen' for measuring the developed secondary flow and heat/mass transfer due to thermosolutal Marangoni convection as well as the possibility to analyze and plan the drop tower for such experiments using the COMGA PC-based system.

Removal of copper(II) from some environmental samples by sorptive-flotation using powdered marble wastes as sorbents and oleic acid as surfactant.

PubMed

Ghazy, S E; Samra, S E; Mahdy, A F M; El-Morsy, S M

2004-11-01

A simple and economic experimental sorptive -flotation procedure is presented for the removal of copper(II) species from aqueous solutions. It is based on using powdered marble wastes (PMW), which are widespread and inexpensive and may represent an environmental problem, as the effective inorganic sorbent and oleic (HOL) as the surfactant. The main parameters (i.e. initial solution pH, sorbent, surfactant and copper concentrations, stirring times, ionic strength, temperature and the presence of foreign ions) influencing the flotation of PMW and /or Cu(II) were examined. Nearly, 100% of PMW and Cu(II) were removed from aqueous solutions at pH7 after stirring for 10 min and at room temperature, (approximately 25 degrees C). The procedure was successfully applied to recover Cu(II) spiked to some natural water samples. A mechanism for sorption and flotation is suggested.

Effects of Thermal Resistance on One-Dimensional Thermal Analysis of the Epidermal Flexible Electronic Devices Integrated with Human Skin

NASA Astrophysics Data System (ADS)

Li, He; Cui, Yun

2017-12-01

Nowadays, flexible electronic devices are increasingly used in direct contact with human skin to monitor the real-time health of human body. Based on the Fourier heat conduction equation and Pennes bio-heat transfer equation, this paper deduces the analytical solutions of one - dimensional heat transfer for flexible electronic devices integrated with human skin under the condition of a constant power. The influence of contact thermal resistance between devices and skin is considered as well. The corresponding finite element model is established to verify the correctness of analytical solutions. The results show that the finite element analysis agrees well with the analytical solution. With bigger thermal resistance, temperature increase of skin surface will decrease. This result can provide guidance for the design of flexible electronic devices to reduce the negative impact that exceeding temperature leave on human skin.

Tricyanomethane and Its Ketenimine Tautomer: Generation from Different Precursors and Analysis in Solution, Argon Matrix, and as a Single Crystal.

PubMed

Banert, Klaus; Chityala, Madhu; Hagedorn, Manfred; Beckers, Helmut; Stüker, Tony; Riedel, Sebastian; Rüffer, Tobias; Lang, Heinrich

2017-08-01

Solutions of azidomethylidenemalononitrile were photolyzed at low temperatures to produce the corresponding 2H-azirine and tricyanomethane, which were analyzed by low-temperature NMR spectroscopy. The latter product was also observed after short thermolysis of the azide precursor in solution whereas irradiation of the azide isolated in an argon matrix did not lead to tricyanomethane, but to unequivocal detection of the tautomeric ketenimine by IR spectroscopy for the first time. When the long-known "aquoethereal" greenish phase generated from potassium tricyanomethanide, dilute sulfuric acid, and diethyl ether was rapidly evaporated and sublimed, a mixture of hydronium tricyanomethanide and tricyanomethane was formed instead of the previously claimed ketenimine tautomer. Under special conditions of sublimation, single crystals of tricyanomethane could be isolated, which enabled the analysis of the molecular structure by X-ray diffraction. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Removal of Calcium from Scheelite Leaching Solution by Addition of CaSO4 Inoculating Crystals

NASA Astrophysics Data System (ADS)

Liu, Wenting; Li, Yongli; Zeng, Dewen; Li, Jiangtao; Zhao, Zhongwei

2018-04-01

In this work, the solubility behaviors of gypsum and anhydrite in the H2SO4-H3PO4-H2O system were investigated over the temperature range T = 30-80°C, and the results showed that the solubility of anhydrite was considerably lower than that of gypsum. On the basis of the differential solubilities of gypsum and anhydrite, a method was developed to remove calcium from the scheelite leaching solution by adding anhydrite as an inoculating crystal. The effects of the reaction time, concentration of the CaSO4 inoculating crystals, and temperature were investigated. With an addition of CaSO4 inoculating crystals at a concentration of 60 g/L, the Ca2+ concentration of the scheelite leaching solution decreased to a low level of approximately 0.76 g/L after 10 h at 70°C.

Cultivation and energy efficient harvesting of microalgae using thermoreversible sol-gel transition

PubMed Central

Estime, Bendy; Ren, Dacheng; Sureshkumar, Radhakrishna

2017-01-01

Microalgae represent a promising source of renewable biomass for the production of biofuels and valuable chemicals. However, energy efficient cultivation and harvesting technologies are necessary to improve economic viability. A Tris-Acetate-Phosphate-Pluronic (TAPP) medium that undergoes a thermoreversible sol-gel transition is developed to efficiently culture and harvest microalgae without affecting the productivity as compared to that in traditional culture in a well-mixed suspension. After seeding microalgae in the TAPP medium in a solution phase at 15 °C, the temperature is increased by 7 °C to induce gelation. Within the gel, microalgae are observed to grow in large clusters rather than as isolated cells. The settling velocity of the microalgal clusters is approximately ten times larger than that of individual cells cultured in typical solution media. Such clusters are easily harvested gravimetrically by decreasing the temperature to bring the medium to a solution phase. PMID:28102313

High efficiency solution processed sintered CdTe nanocrystal solar cells: the role of interfaces.

PubMed

Panthani, Matthew G; Kurley, J Matthew; Crisp, Ryan W; Dietz, Travis C; Ezzyat, Taha; Luther, Joseph M; Talapin, Dmitri V

2014-02-12

Solution processing of photovoltaic semiconducting layers offers the potential for drastic cost reduction through improved materials utilization and high device throughput. One compelling solution-based processing strategy utilizes semiconductor layers produced by sintering nanocrystals into large-grain semiconductors at relatively low temperatures. Using n-ZnO/p-CdTe as a model system, we fabricate sintered CdTe nanocrystal solar cells processed at 350 °C with power conversion efficiencies (PCE) as high as 12.3%. JSC of over 25 mA cm(-2) are achieved, which are comparable or higher than those achieved using traditional, close-space sublimated CdTe. We find that the VOC can be substantially increased by applying forward bias for short periods of time. Capacitance measurements as well as intensity- and temperature-dependent analysis indicate that the increased VOC is likely due to relaxation of an energetic barrier at the ITO/CdTe interface.

Microwave-assisted synthesis of carbon nanotubes from tannin, lignin, and derivatives

DOEpatents

Viswanathan, Tito

2014-06-17

A method of synthesizing carbon nanotubes. In one embodiment, the method includes the steps of: (a) dissolving a first amount of a first transition-metal salt and a second amount of a second transition-metal salt in water to form a solution; (b) adding a third amount of tannin to the solution to form a mixture; (c) heating the mixture to a first temperature for a first duration of time to form a sample; and (d) subjecting the sample to a microwave radiation for a second duration of time effective to produce a plurality of carbon nanotubes.

Short-term stability studies of ampicillin and cephalexin in aqueous solution and human plasma: Application of least squares method in Arrhenius equation.

PubMed

do Nascimento, Ticiano Gomes; de Jesus Oliveira, Eduardo; Basílio Júnior, Irinaldo Diniz; de Araújo-Júnior, João Xavier; Macêdo, Rui Oliveira

2013-01-25

A limited number of studies with application of the Arrhenius equation have been reported to drugs and biopharmaceuticals in biological fluids at frozen temperatures. This paper describes stability studies of ampicillin and cephalexin in aqueous solution and human plasma applying the Arrhenius law for determination of adequate temperature and time of storage of these drugs using appropriate statistical analysis. Stability studies of the beta-lactams in human plasma were conducted at temperatures of 20°C, 2°C, -20°C and also during four cycles of freeze-thawing. Chromatographic separation was achieved using a Shimpak C(18) column, acetonitrile as organic modifier and detection at 215nm. LC-UV-MS/MS was used to demonstrate the conversion of ampicillin into two diastereomeric forms of ampicilloic acid. Stability studies demonstrated degradation greater than 10% for ampicillin in human plasma at 20°C, 2°C and -20°C after 15h, 2.7days, 11days and for cephalexin at the same temperatures after 14h, 3.4days and 19days, respectively, and after the fourth cycle of freezing-thawing. The Arrhenius plot showed good prediction for the ideal temperature and time of storage for ampicillin (52days) and cephalexin (151days) at a temperature of -40°C, but statistical analysis (least squares method) must be applied to avoid incorrect extrapolations and estimated values out uncertainty limits. Copyright © 2012 Elsevier B.V. All rights reserved.

Melt Convection Effects in the Bridgman Crystal Growth of an Alloy Under Microgravity Conditions

NASA Technical Reports Server (NTRS)

Simpson James E.; Garimella, Suresh V.; deGroh, Henry C., III; Abbaschian, Reza

1998-01-01

The solidification of a dilute bismuth-tin alloy under Bridgman crystal growth conditions is investigated in support of NASA's MEPHISTO space shuttle flight experiment. Computations are performed in two-dimensions with a uniform grid. The simulation includes the species-concentration, temperature and flow fields, as well as conduction in the ampoule. Fully transient simulations have been performed; no simplifying steady state approximations are used. Results are obtained under microgravity conditions for pure bismuth, and Bismuth-0.1 at.% Sn and Bi-1.0 at.% Sn alloys. The concentration dependence of the melting temperature is neglected; the solid/liquid interface temperature is assumed to be the melting temperature of pure bismuth for all cases studied. For the Bi-1.0 at.% Sn case the results indicate that a secondary convective cell, driven by solutal gradients, forms near the interface. The magnitude of the velocities in this cell increases with time; this causes increasing solute segregation at the liquid/solid interface.

A numerical study on dual-phase-lag model of bio-heat transfer during hyperthermia treatment.

PubMed

Kumar, P; Kumar, Dinesh; Rai, K N

2015-01-01

The success of hyperthermia in the treatment of cancer depends on the precise prediction and control of temperature. It was absolutely a necessity for hyperthermia treatment planning to understand the temperature distribution within living biological tissues. In this paper, dual-phase-lag model of bio-heat transfer has been studied using Gaussian distribution source term under most generalized boundary condition during hyperthermia treatment. An approximate analytical solution of the present problem has been done by Finite element wavelet Galerkin method which uses Legendre wavelet as a basis function. Multi-resolution analysis of Legendre wavelet in the present case localizes small scale variations of solution and fast switching of functional bases. The whole analysis is presented in dimensionless form. The dual-phase-lag model of bio-heat transfer has compared with Pennes and Thermal wave model of bio-heat transfer and it has been found that large differences in the temperature at the hyperthermia position and time to achieve the hyperthermia temperature exist, when we increase the value of τT. Particular cases when surface subjected to boundary condition of 1st, 2nd and 3rd kind are discussed in detail. The use of dual-phase-lag model of bio-heat transfer and finite element wavelet Galerkin method as a solution method helps in precise prediction of temperature. Gaussian distribution source term helps in control of temperature during hyperthermia treatment. So, it makes this study more useful for clinical applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fluid temperature at the corneal endothelium during phacoemulsification: comparison of an ophthalmic viscosurgical device and balanced salt solution using the finite element method.

PubMed

Reepolmaha, Somporn; Limtrakarn, Wiroj; Uthaisang-Tanechpongtamb, Wanlaya; Dechaumphai, Pramote

2010-01-01

The purpose of this study was to estimate and compare the temperatures of two different anterior chamber solutions at the corneal endothelial level during phacoemulsification. An ophthalmic viscosurgical device (OVD) and balanced salt solution (BSS) were compared using the finite element method (FEM). The thermal properties of an OVD (IAL-F) and BSS were studied in an experimental setting. A computer-aided design model of ocular anatomy was created in two dimensions. The phaco needle was considered to be the only source of heat generation. Then, the FEM was used to demonstrate the transient temperature distribution in the two ocular models at 10, 20, 30, 40, 50 and 60 s. In these models, the anterior chamber was filled with IAL-F (IAL-F model) or BSS (BSS model). The heat generation rate of the phaco needle was 0.0004 cal/s/mm(2). The maximum corneal endothelial temperatures for the two models at 60 s were 52.67 and 41.57 degrees C, respectively. The experimental IAL-F model showed fewer changes in temperature for any given time and location. At larger distances from the heat source, less temperature variation was detected. Phacoemulsification is a potential heat-generating procedure performed between the delicate anterior chamber structures. During this procedure, IAL-F protects the endothelium against heat better than BSS. Copyright 2009 S. Karger AG, Basel.

Transient natural convection with density inversion from a horizontal cylinder

NASA Astrophysics Data System (ADS)

Wang, P.; Kahawita, R.; Nguyen, D. L.

1992-01-01

This paper is devoted to a numerical investigation of the free convection flow about a horizontal cylinder maintained at 0 °C in a water ambient close to the point of maximum density. Complete numerical solutions covering both the transient as well as steady state have been obtained. Principal results indicate that the proximity of the ambient temperature to the point of maximum density plays an important role in the type of convection pattern that may be obtained. When the ambient temperature is within 4.7 °C

Ethanol and sodium acetate as a preservation method to delay degradation of environmental DNA

USGS Publications Warehouse

Ladell, Bridget A.; Walleser, Liza R.; McCalla, S. Grace; Erickson, Richard A.; Amberg, Jon J.

2018-01-01

Environmental DNA (eDNA) samples that are collected from remote locations depend on rapid stabilization of the DNA. The degradation of eDNA in water samples is minimized when samples are stored at ≤ 4 °C. Developing a preservation technique to maintain eDNA integrity at room temperature would allow a wider range of locations to be sampled. We evaluated an ethanol and sodium acetate solution to maintain the integrity of the DNA samples for the time between collection and lab testing. For this evaluation, replicate water samples taken from a tank housing Asian carp were placed on ice or held at room temperature. At both temperatures, water samples were left untreated or were preserved with an ethanol and sodium acetate solution (EtOH–NaAc). Every day for 6 days following collection, a subset of the samples was removed from each preservation method and DNA was extracted and nuclear and mitochondrial markers were assayed with qPCR. Results showed comparable persistence of DNA between iced samples without the EtOH–NaAc treatment and samples that received EtOH–NaAc treatment that were kept at room temperature. We found that DNA can be amplified from preserved samples using an EtOH–NaAc solution after up to 7 days at room temperature.

A miniature integrated multimodal sensor for measuring pH, EC and temperature for precision agriculture.

PubMed

Futagawa, Masato; Iwasaki, Taichi; Murata, Hiroaki; Ishida, Makoto; Sawada, Kazuaki

2012-01-01

Making several simultaneous measurements with different kinds of sensors at the same location in a solution is difficult because of crosstalk between the sensors. In addition, because the conditions at different locations in plant beds differ, in situ measurements in agriculture need to be done in small localized areas. We have fabricated a multimodal sensor on a small Si chip in which a pH sensor was integrated with electrical conductivity (EC) and temperature sensors. An ISFET with a Si(3)N(4) membrane was used for the pH sensor. For the EC sensor, the electrical conductivity between platinum electrodes was measured, and the temperature sensor was a p-n junction diode. These are some of the most important measurements required for controlling the conditions in plant beds. The multimodal sensor can be inserted into a plant bed for in situ monitoring. To confirm the absence of crosstalk between the sensors, we made simultaneous measurements of pH, EC, and temperature of a pH buffer solution in a plant bed. When the solution was diluted with hot or cold water, the real time measurements showed changes to the EC and temperature, but no change in pH. We also demonstrated that our sensor was capable of simultaneous in situ measurements in rock wool without being affected by crosstalk.

A Miniature Integrated Multimodal Sensor for Measuring pH, EC and Temperature for Precision Agriculture

PubMed Central

Futagawa, Masato; Iwasaki, Taichi; Murata, Hiroaki; Ishida, Makoto; Sawada, Kazuaki

2012-01-01

Making several simultaneous measurements with different kinds of sensors at the same location in a solution is difficult because of crosstalk between the sensors. In addition, because the conditions at different locations in plant beds differ, in situ measurements in agriculture need to be done in small localized areas. We have fabricated a multimodal sensor on a small Si chip in which a pH sensor was integrated with electrical conductivity (EC) and temperature sensors. An ISFET with a Si3N4 membrane was used for the pH sensor. For the EC sensor, the electrical conductivity between platinum electrodes was measured, and the temperature sensor was a p-n junction diode. These are some of the most important measurements required for controlling the conditions in plant beds. The multimodal sensor can be inserted into a plant bed for in situ monitoring. To confirm the absence of crosstalk between the sensors, we made simultaneous measurements of pH, EC, and temperature of a pH buffer solution in a plant bed. When the solution was diluted with hot or cold water, the real time measurements showed changes to the EC and temperature, but no change in pH. We also demonstrated that our sensor was capable of simultaneous in situ measurements in rock wool without being affected by crosstalk. PMID:22969403

Formulation and stability of an extemporaneous 0.02% chlorhexidine digluconate ophthalmic solution.

PubMed

Lin, Shu-Chiao; Huang, Chih-Fen; Shen, Li-Jiuan; Wang, Hsueh-Ju; Lin, Chia-Yu; Wu, Fe-Lin Lin

2015-12-01

Acanthamoeba keratitis is difficult to treat because Acanthamoeba cysts are resistant to the majority of antimicrobial agents. Despite the efficacy of 0.02% chlorhexidine in treating Acanthamoeba keratitis, a lack of data in the literature regarding the formulation's stability limits its clinical use. The objective of this study was to develop an optimal extemporaneous 0.02% chlorhexidine digluconate ophthalmic formulation for patients in need. With available active pharmaceutical ingredients, 0.02% chlorhexidine digluconate sample solutions were prepared by diluting with BSS Plus Solution or acetate buffer. Influences of the buffer, type of container, and temperature under daily-open condition were assessed based on the changes of pH values and chlorhexidine concentrations of the test samples weekly. To determine the beyond-use date, the optimal samples were stored at 2-8°C or room temperature, and analyzed at time 0 and at Week 1, Week 2, Week 3, Week 4, Week 5, Week 8, Week 12, and Week 24. Despite chlorhexidine exhibiting better stability in acetate buffer than in BSS solution, its shelf-life was < 14 days when stored in a light-resistant low-density polyethylene container. The acetate-buffered 0.02% chlorhexidine digluconate solution stored in light-resistant high-density polyethylene eyedroppers did not exhibit significant changes in pH or strength at any time interval. The acetate-buffered 0.02% chlorhexidine digluconate ophthalmic solution stored in light-resistant high-density polyethylene eyedroppers demonstrated excellent stability at 2-25°C for 6 months after being sealed and for 1 month after opening. This finding will enable us to prepare 0.02% chlorhexidine digluconate ophthalmic solutions based on a doctor's prescription. Copyright © 2014. Published by Elsevier B.V.

Supercooling as a Viable Non-Freezing Cell Preservation Method of Rat Hepatocytes

PubMed Central

Usta, O. Berk; Kim, Yeonhee; Ozer, Sinan; Bruinsma, Bote G.; Lee, Jungwoo; Demir, Esin; Berendsen, Tim A.; Puts, Catheleyne F.; Izamis, Maria-Louisa; Uygun, Korkut; Uygun, Basak E.; Yarmush, Martin L.

2013-01-01

Supercooling preservation holds the potential to drastically extend the preservation time of organs, tissues and engineered tissue products, and fragile cell types that do not lend themselves well to cryopreservation or vitrification. Here, we investigate the effects of supercooling preservation (SCP at -4oC) on primary rat hepatocytes stored in cryovials and compare its success (high viability and good functional characteristics) to that of static cold storage (CS at +4oC) and cryopreservation. We consider two prominent preservation solutions a) Hypothermosol (HTS-FRS) and b) University of Wisconsin solution (UW) and a range of preservation temperatures (-4 to -10 oC). We find that there exists an optimum temperature (-4oC) for SCP of rat hepatocytes which yields the highest viability; at this temperature HTS-FRS significantly outperforms UW solution in terms of viability and functional characteristics (secretions and enzymatic activity in suspension and plate culture). With the HTS-FRS solution we show that the cells can be stored for up to a week with high viability (~56%); moreover we also show that the preservation can be performed in large batches (50 million cells) with equal or better viability and no loss of functionality as compared to smaller batches (1.5 million cells) performed in cryovials. PMID:23874947

Accelerated in vitro release testing of implantable PLGA microsphere/PVA hydrogel composite coatings.

PubMed

Shen, Jie; Burgess, Diane J

2012-01-17

Dexamethasone loaded poly(lactic-co-glycolic acid) (PLGA) microsphere/PVA hydrogel composites have been investigated as an outer drug-eluting coating for implantable devices such as glucose sensors to counter negative tissue responses to implants. The objective of this study was to develop a discriminatory, accelerated in vitro release testing method for this drug-eluting coating using United States Pharmacopeia (USP) apparatus 4. Polymer degradation and drug release kinetics were investigated under "real-time" and accelerated conditions (i.e. extreme pH, hydro-alcoholic solutions and elevated temperatures). Compared to "real-time" conditions, the initial burst and lag phases were similar using hydro-alcoholic solutions and extreme pH conditions, while the secondary apparent zero-order release phase was slightly accelerated. Elevated temperatures resulted in a significant acceleration of dexamethasone release. The accelerated release data were able to predict "real-time" release when applying the Arrhenius equation. Microsphere batches with faster and slower release profiles were investigated under "real-time" and elevated temperature (60°C) conditions to determine the discriminatory ability of the method. The results demonstrated both the feasibility and the discriminatory ability of this USP apparatus 4 method for in vitro release testing of drug loaded PLGA microsphere/PVA hydrogel composites. This method may be appropriate for similar drug/device combination products and drug delivery systems. Copyright © 2011 Elsevier B.V. All rights reserved.

Extracting concrete thermal characteristics from temperature time history of RC column exposed to standard fire.

PubMed

Kim, Jung J; Youm, Kwang-Soo; Reda Taha, Mahmoud M

2014-01-01

A numerical method to identify thermal conductivity from time history of one-dimensional temperature variations in thermal unsteady-state is proposed. The numerical method considers the change of specific heat and thermal conductivity with respect to temperature. Fire test of reinforced concrete (RC) columns was conducted using a standard fire to obtain time history of temperature variations in the column section. A thermal equilibrium model in unsteady-state condition was developed. The thermal conductivity of concrete was then determined by optimizing the numerical solution of the model to meet the observed time history of temperature variations. The determined thermal conductivity with respect to temperature was then verified against standard thermal conductivity measurements of concrete bricks. It is concluded that the proposed method can be used to conservatively estimate thermal conductivity of concrete for design purpose. Finally, the thermal radiation properties of concrete for the RC column were estimated from the thermal equilibrium at the surface of the column. The radiant heat transfer ratio of concrete representing absorptivity to emissivity ratio of concrete during fire was evaluated and is suggested as a concrete criterion that can be used in fire safety assessment.

Extracting Concrete Thermal Characteristics from Temperature Time History of RC Column Exposed to Standard Fire

PubMed Central

2014-01-01

A numerical method to identify thermal conductivity from time history of one-dimensional temperature variations in thermal unsteady-state is proposed. The numerical method considers the change of specific heat and thermal conductivity with respect to temperature. Fire test of reinforced concrete (RC) columns was conducted using a standard fire to obtain time history of temperature variations in the column section. A thermal equilibrium model in unsteady-state condition was developed. The thermal conductivity of concrete was then determined by optimizing the numerical solution of the model to meet the observed time history of temperature variations. The determined thermal conductivity with respect to temperature was then verified against standard thermal conductivity measurements of concrete bricks. It is concluded that the proposed method can be used to conservatively estimate thermal conductivity of concrete for design purpose. Finally, the thermal radiation properties of concrete for the RC column were estimated from the thermal equilibrium at the surface of the column. The radiant heat transfer ratio of concrete representing absorptivity to emissivity ratio of concrete during fire was evaluated and is suggested as a concrete criterion that can be used in fire safety assessment. PMID:25180197

Shelf-life of bioprosthetic heart valves: a structural and mechanical study.

PubMed

Julien, M; Létouneau, D R; Marois, Y; Cardou, A; King, M W; Guidoin, R; Chachra, D; Lee, J M

1997-04-01

This study was undertaken to evaluate the influence of storage conditions on the shelf-life of porcine bioprosthetic valves. Fifty-five unimplanted porcine bioprostheses have been evaluated. The valves were stored in 0.5% buffered glutaraldehyde solution for different periods of time (7, 23 and 32 months). Twenty-eight valves were refrigerated while the remaining valves were stored at room temperature. The pH of the glutaraldehyde solution at room temperature decreased with time of storage, while that kept in the refrigerator remained stable over the course of the study. Macroscopic observations showed that the valve tissues kept at room temperature, especially for the periods of 23 and 32 months, became darker and more yellow in colour, whereas the refrigerated specimens exhibited no such changes in appearance. Scanning electron microscopy analysis revealed no noticeable differences on the surfaces of the leaflets stored under different conditions. Mechanical tests, including stress-strain response, stress relaxation and fracture behaviour, were carried out. Analysis of variance showed that the storage temperature, but not the length of storage, had a significant effect on some mechanical properties. The stress relaxation at 1000 s (P = 0.05), the ultimate tensile strength (P = 0.01) and the strain at fracture (P = 0.04) were all higher after storage at room temperature compared to the results after refrigeration. No statistically significant changes in the denaturation temperature of the collagen were observed between the different storage conditions. In conclusion, the storage temperature appears to have some influence on the bioprosthetic tissue. The bioprostheses stored under ambient conditions experience changes which may influence their longterm in vivo performance.

Finite-temperature time-dependent variation with multiple Davydov states

NASA Astrophysics Data System (ADS)

Wang, Lu; Fujihashi, Yuta; Chen, Lipeng; Zhao, Yang

2017-03-01

The Dirac-Frenkel time-dependent variational approach with Davydov Ansätze is a sophisticated, yet efficient technique to obtain an accurate solution to many-body Schrödinger equations for energy and charge transfer dynamics in molecular aggregates and light-harvesting complexes. We extend this variational approach to finite temperature dynamics of the spin-boson model by adopting a Monte Carlo importance sampling method. In order to demonstrate the applicability of this approach, we compare calculated real-time quantum dynamics of the spin-boson model with that from numerically exact iterative quasiadiabatic propagator path integral (QUAPI) technique. The comparison shows that our variational approach with the single Davydov Ansätze is in excellent agreement with the QUAPI method at high temperatures, while the two differ at low temperatures. Accuracy in dynamics calculations employing a multitude of Davydov trial states is found to improve substantially over the single Davydov Ansatz, especially at low temperatures. At a moderate computational cost, our variational approach with the multiple Davydov Ansatz is shown to provide accurate spin-boson dynamics over a wide range of temperatures and bath spectral densities.

Rapid photogeneration of silver nanoparticles in ethanolic solution: a kinetic study.

PubMed

Yahyaei, Bahareh; Azizian, Saeid

2013-01-15

Ag nanoparticles have been synthesized via UV irradiation of ethanolic solution of AgNO3 in presence of pluronic F127 surfactant. This study is aimed at developing a rapid, simple and green method to prepare Ag nanoparticles and understanding its generation kinetics. The formation dependency of silver nanoparticles on the concentration of reactants, UV exposure time and temperature has been investigated by using UV-vis spectroscopy. The 2D map technique has been used for the first time to estimate the switching time between the nucleation and growth of Ag nanoparticles. Appropriate kinetic models were used for modelling of both stages. Copyright © 2012 Elsevier B.V. All rights reserved.

Influence of trace elements on stabilization of aqueous solutions of ascorbic acid.

PubMed

Dolińska, Barbara; Ostróżka-Cieślik, Aneta; Caban, Artur; Rimantas, Klimas; Leszczyńska, Lucyna; Ryszka, Florian

2012-12-01

Together with vitamin C, zinc, selenium, manganese, and magnesium play a vital role in the preservation of organs scheduled for transplantation. In the present study, it is shown that addition of 1 mg/l of these elements influences the stability of 0.3 mM ascorbic acid solutions. The solution's stability was estimated using an accelerated stability test. The concentration of vitamin C was measured using a validated spectrophotometric method, which uses the reduction of 2,6-dichlorophenoloindophenol by ascorbic acid. Elevated temperatures, the factor accelerating substances' decomposition reaction rate, were used in the tests. The research was conducted at two temperatures at intervals of 10 °C: 80 ± 0.1 and 90 ± 0.1 °C. It was stated that the studied substances' decomposition occurred in accordance with the equation for first-order reactions. The function of the logarithmic concentration (log%C) over time was revealed to be rectilinear. This dependence was used to determine the kinetics of decomposition reaction rate parameters. The stabilization of vitamin C solutions was measured as the time in which 10 % of the substance decomposed at 20 and 0 °C. Addition of Se(IV) or Mg(II) ions significantly increase the stability of ascorbic acid solution (∼34 and ∼16 %, respectively), but Zn(II) causes a significant decrease in stability by ∼23 %. Addition of Mn(II) has no significant influence on vitamin C stability.

The challenges of heat sterilization of peritoneal dialysis solutions: is there an alternative?

PubMed

Hanrahan, Conor T; Himmele, Rainer; Diaz-Buxo, Jose A

2012-01-01

Peritoneal dialysis (PD) solutions are currently sterilized in an autoclave using high-temperature saturated steam. Although thermal methods are an effective means of sterilization, the heating of PD solutions results in the formation of toxic glucose degradation products (GDPs). Here, we review basic concepts in the sterilization of PD solutions and discuss possible alternatives to steam sterilization, including filtration, ohmic heat, ionizing radiation, and pulsed ultraviolet light. Although the latter methods have several advantages, many also have prohibitive limitations or have not been adequately studied for use on PD solutions. Thus, in the absence of suitable alternatives, conventional heat sterilization, in combination with low-GDP manufacturing practices, remains the best option at the present time.

Mercury removal from aqueous solutions by zinc cementation.

PubMed

Ku, Young; Wu, Ming-Huan; Shen, Yung-Shen

2002-01-01

The main purpose of this research is to study the addition effect of the surfactant and other operating factors on the treatment of wastewater containing mercury ions in aqueous solution by cementation with sacrificing metal, zinc. The removal of mercury ions from aqueous solutions by cementation of zinc powder was found to be a function of solution pH and temperature, amount of zinc, concentration of mercury ion, contact time and the addition of several organic surfactants. Cementation of mercury was shown to be a feasible process to achieve a very high degree of mercury removal over a broad operational range within a fairly reasonable contact time. The reaction rate is approximately first order with respect to the concentration of mercury ion in aqueous solution. Among the surfactants used in this study, only the presence of SDS, an anionic surfactant, slightly enhanced the cementation rate of mercury. The presence of CTAB and Triton-X100 retarded the cementation of mercury by zinc.

Flow properties of a series of experimental thermoplastic polymides

NASA Technical Reports Server (NTRS)

Burks, H. D.; Nelson, J. B.; Price, H. L.

1981-01-01

The softening temperature to degradation temperature range of the polymers was about 440 to 650 K. All of the polymers retained small amounts of solvent as indicated by an increase in T(sub g) as the polymers were dried. The flow properties showed that all three polymers had very high apparent viscosities and would require high pressures and/or high temperatures and/or long times to obtain adequate flow in prepregging and molding. Although none was intended for such application, two of the polymers were combined with carbon fibers by solution prepregging. The prepregs were molded into laminates at temperatures and times, the selection of which was guided by the results from the flow measurements. These laminates had room temperature short beam shear strength similar to that of carbon fiber laminates with a thermosetting polyimide matrix. However, the strength had considerable scatter, and given the difficult processing, these polymides probably would not be suitable for continuous fiber composites.

Reducing the loss of vaccines from accidental freezing in the cold chain: the experience of continuous temperature monitoring in Tunisia.

PubMed

Lloyd, John; Lydon, Patrick; Ouhichi, Ramzi; Zaffran, Michel

2015-02-11

Accidental freezing of vaccines is a growing threat and a real risk for national immunization programs when the potency of many vaccines can be compromised if these are exposed to sub-zero temperatures in the cold chain. In Tunisia, this issue is compounded by using sub-standard domestic cold chain equipment instead of equipping the program with medical refrigerators designed specifically for storing vaccines and temperature sensitive pharmaceuticals. Against this backdrop, this paper presents the findings of a demonstration project conducted in Tunisia in 2012 that tested the impact of introducing several freeze prevention solutions to mitigate the risk of accidental freezing of vaccines. The main finding is that, despite the continued use of underperforming domestic refrigerators, continuous temperature monitoring using new technologies combined with other technological interventions significantly reduced the prevalence of accidental exposure to freezing temperatures. These improvements were noticed for cold chain storage at regional, district and health center levels, and during the transport legs that were part of the demonstration conducted in the regions of Kasserine in the South-Eastern part of Tunisia. Subsequent to introducing these freeze prevention solutions, the incidence of freeze alarms was reduced and the percent of time the temperatures dropped below the 2 °C recommended threshold. The incidence of freeze alarms at health center level was reduced by 40%. Lastly, the solutions implemented reduced risk of freezing during transport from 13.8% to 1.7%. Although the solution implemented is not optimal in the longer term because domestic refrigerators are used extensively in district stores and health centers, the risk of accidental freezing is significantly reduced by introducing the practice of continuous temperature monitoring as a standard. The management of the cold chain equipment was strengthened as a result which helps protect the potency of vaccines to the areas of most difficult access. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Entrainment in solution of an oscillating NADH oxidase activity from the bovine milk fat globule membrane with a temperature-compensated period length suggestive of an ultradian time-keeping (clock) function

NASA Technical Reports Server (NTRS)

Morre, D. James; Lawler, Juliana; Wang, Sui; Keenan, Thomas W.; Morre, Dorothy M.

2002-01-01

Entrainment in solution of an oscillating activity with a temperature compensated period of 24 min is described for a NADH oxidase (NOX) activity of the bovine milk fat globule membrane, a derivative of the mammary epithelial cell plasma membrane. The period of 24 min remained unchanged at 17 degrees C, 27 degrees C and 37 degrees C whereas the amplitude approximately doubled with each 10 degree C rise in temperature (Q(10)congruent with 2). The periodicity was observed with both intact milk fat globule membranes and with detergent-solubilized membranes, demonstrating that the oscillations did not require an association with membranes. The periodicity was not the result of instrument variation or of chemical interactions among reactants in solution. Preparations with different periodicities entrained (autosynchronized) when mixed. Upon mixing, the preparations exhibited two oscillatory patterns but eventually a single pattern representing the mean of the farthest separated maxima of the two preparations analyzed separately emerged. The cell surface NOX protein is the first reported example of an entrainable biochemical entity with a temperature-compensated periodicity potentially capable of functioning as an ultradian or circadian clock driver.

A Novel Approach Toward Fabrication of High Performance Thin Film Composite Polyamide Membranes.

PubMed

Khorshidi, Behnam; Thundat, Thomas; Fleck, Brian A; Sadrzadeh, Mohtada

2016-02-29

A practical method is reported to enhance water permeability of thin film composite (TFC) polyamide (PA) membranes by decreasing the thickness of the selective PA layer. The composite membranes were prepared by interfacial polymerization (IP) reaction between meta-phenylene diamine (MPD)-aqueous and trimesoyl chloride (TMC)-organic solvents at the surface of polyethersulfone (PES) microporous support. Several PA TFC membranes were prepared at different temperatures of the organic solution ranging from -20 °C to 50 °C. The physico-chemical and morphological properties of the synthesized membranes were carefully characterized using serval analytical techniques. The results confirmed that the TFC membranes, synthesized at sub-zero temperatures of organic solution, had thinner and smoother PA layer with a greater degree of cross-linking and wettability compared to the PA films prepared at 50 °C. We demonstrated that reducing the temperature of organic solution effectively decreased the thickness of the PA active layer and thus enhanced water permeation through the membranes. The most water permeable membrane was prepared at -20 °C and exhibited nine times higher water flux compared to the membrane synthesized at room temperature. The method proposed in this report can be effectively applied for energy- and cost-efficient development of high performance nanofiltration and reverse osmosis membranes.

Guava (Psidium guajava) leaf powder: novel adsorbent for removal of methylene blue from aqueous solutions.

PubMed

Ponnusami, V; Vikram, S; Srivastava, S N

2008-03-21

Batch sorption experiments were carried out using a novel adsorbent, guava leaf powder (GLP), for the removal of methylene blue (MB) from aqueous solutions. Potential of GLP for adsorption of MB from aqueous solution was found to be excellent. Effects of process parameters pH, adsorbent dosage, concentration, particle size and temperature were studied. Temperature-concentration interaction effect on dye uptake was studied and a quadratic model was proposed to predict dye uptake in terms of concentration, time and temperature. The model conforms closely to the experimental data. The model was used to find optimum temperature and concentration that result in maximum dye uptake. Langmuir model represent the experimental data well. Maximum dye uptake was found to be 295mg/g, indicating that GLP can be used as an excellent low-cost adsorbent. Pseudo-first-order, pseudo-second order and intraparticle diffusion models were tested. From experimental data it was found that adsorption of MB onto GLP follow pseudo second order kinetics. External diffusion and intraparticle diffusion play roles in adsorption process. Free energy of adsorption (DeltaG degrees ), enthalpy change (DeltaH degrees ) and entropy change (DeltaS degrees ) were calculated to predict the nature of adsorption. Adsorption in packed bed was also evaluated.

Equilibrium and kinetic modelling of chromium(III) sorption by animal bones.

PubMed

Chojnacka, Katarzyna

2005-04-01

The paper discusses sorption of Cr(III) ions from aqueous solutions by animal bones. Animal bones were found to be an efficient sorbent with the maximum experimentally determined sorption capacity in the range 29-194 mg g(-1) that depended on pH and temperature. The maximum experimentally determined sorption capacity was obtained at 50 degrees C, pH 5. Batch kinetics and equilibrium experiments were performed in order to investigate the influence of contact time, initial concentration of sorbate and sorbent, temperature and pH. It was found that sorption capacity increased with increase of Cr(III) concentration, temperature and initial pH of metal solution. Mathematical models describing kinetics and statics of sorption were proposed. It was found that process kinetics followed the pseudo-second-order pattern. The influence of sorbent concentration was described with Langmuir-type equation and the influence of sorbate concentration was described with empirical dependence. The models were positively verified.

Complex Heat Exchangers for Improved Performance

NASA Astrophysics Data System (ADS)

Bran, Gabriela Alejandra

After a detailed literature review, it was determined that there was a need for a more comprehensive study on the transient behavior of heat exchangers. Computational power was not readily available when most of the work on transient heat exchangers was done (1956 - 1986), so most of these solutions have restrictions, or very specific assumptions. More recently, authors have obtained numerical solutions for more general problems (2003 - 2013), but they have investigated very specific conditions, and cases. For a more complex heat exchanger (i.e. with heat generation), the transient solutions from literature are no longer valid. There was a need to develop a numerical model that relaxes the restrictions of current solutions to explore conditions that have not been explored. A one dimensional transient heat exchanger model was developed. There are no restrictions on the fluids and wall conditions. The model is able to obtain a numerical solution for a wide range of fluid properties and mass flow rates. Another innovative characteristic of the numerical model is that the boundary and initial conditions are not limited to constant values. The boundary conditions can be a function of time (i.e. sinusoidal signal), and the initial conditions can be a function of position. Four different cases were explored in this work. In the first case, the start-up of a system was investigated where the whole system is assumed to be at the same temperature. In the second case, the new steady state in case one gets disrupted by a smaller inlet temperature step change. In the third case, the new steady state in case one gets disrupted by a step change in one of the mass flow rates. The response of these three cases show that there are different transient behaviors, and they depend on the conditions imposed on the system. The fourth case is a system that has a sinusoidal time varying inlet temperature for one of the flows. The results show that the sinusoidal behavior at the inlet propagates along the channel. However, the sinusoidal behavior on one of the fluids does not fully translate to the other gets damped by the wall and the heat transfer coefficients that can be barely seen on the other flow. A scaling analysis and a parametric study were performed to determine the influence the different parameters on the system have on the time a heat exchanger takes to reach steady state. The results show the dependency of tst* (time a system takes to reach steady state) on the dimensionless parameters M, C, NTUh, NTUc, and Cw. t st* depends linearly on C and Cw, and it is a power function of M. It was also shown that tst* has a logarithmic dependency on NTUh and NTUc. A correlation was generated to approximate the time a system takes to reach steady state for systems where C w << 1. A more complex heat exchanger with the specific application of solar energy storage was also investigated. This application involves a counter-flow heat exchanger with a reacting flow in one of the channels, and it includes varying properties, heat generation, varying heat transfer coefficient, and axial conduction. The application for this reactor heat exchanger is on solar energy storage, and the goals is to heat up steam to 650 °C by using the ammonia synthesis heat of reaction. One of the concerns for this system is the start-up time and also how disturbances in reacting flow can affect the steam outlet temperature. The transient behavior during the system start-up was presented. In order to achieve the desired outlet steam temperature at a reasonable time, the system must operate at high gas mass flow rates. If the inlet temperature of the gas suffers a step change, it affects the reaction rate as well as the outlet steam temperature. A small perturbation on the gas mass flow rate has an effect on the profile shape. However, the maximum temperature reached by the gas due to reaction is not affected, and consequently, it has little effect on the steam temperature. Axial conduction in the reactor heat exchanger was also investigated, specifically in the gas section. Axial conduction cannot be assumed to be negligible in the reactor heat exchanger because of the iron-based catalytic bed. Results in this section show that axial conduction is detrimental for the system. It was found that for Peclet number greater than 100, axial conduction can be neglected. An alternative solution to address axial conduction was proposed, namely to include a well-insulated non-reacting section (without a catalytic bed) upstream of the reactor. The modified reactor heat exchanger was a novel solution to avoid the negative effect of axial conduction. Results show that by having a non-reacting section, axial conduction becomes unimportant.

Highly sensitive response of solution-processed bismuth sulfide nanobelts for room-temperature nitrogen dioxide detection.

PubMed

Kan, Hao; Li, Min; Song, Zhilong; Liu, Sisi; Zhang, Baohui; Liu, Jingyao; Li, Ming-Yu; Zhang, Guangzu; Jiang, ShengLin; Liu, Huan

2017-11-15

Low dimensional nanomaterials have emerged as candidates for gas sensors owing to their unique size-dependent properties. In this paper, Bi 2 S 3 nanobelts were synthesized via a facile solvothermal process and spin-coated onto alumina substrates at room temperature. The conductometric devices can even sensitively response to the relatively low concentrations of NO 2 at room temperature, and their sensing performance can be effectively enhanced by the ligand exchange treatment with inorganic salts. The Pb(NO 3 ) 2 -treated device exhibited superior sensing performance of 58.8 under 5ppm NO 2 at room-temperature, with the response and recovery time of 28 and 106s. The competitive adsorption of NO 2 against O 2 on Bi 2 S 3 nanobelts, with the enhancement both in gas adsorption and charge transfer caused by the porous network of the very thin Bi 2 S 3 nanobelts, can be a reasonable explanation for the improved performance at room temperature. Their sensitive room-temperature response behaviors combined with the excellent solution processability, made Bi 2 S 3 nanobelts very attractive for the construction of low-cost gas sensors with lower power consumption. Copyright © 2017 Elsevier Inc. All rights reserved.

The formation of supercooled brines, viscous liquids, and low-temperature perchlorate glasses in aqueous solutions relevant to Mars

NASA Astrophysics Data System (ADS)

Toner, J. D.; Catling, D. C.; Light, B.

2014-05-01

Salt solutions on Mars can stabilize liquid water at low temperatures by lowering the freezing point of water. The maximum equilibrium freezing-point depression possible, known as the eutectic temperature, suggests a lower temperature limit for liquid water on Mars; however, salt solutions can supercool below their eutectic before crystallization occurs. To investigate the magnitude of supercooling and its variation with salt composition and concentration, we performed slow cooling and warming experiments on pure salt solutions and saturated soil-solutions of MgSO4, MgCl2, NaCl, NaClO4, Mg(ClO4)2, and Ca(ClO4)2. By monitoring solution temperatures, we identified exothermic crystallization events and determined the composition of precipitated phases from the eutectic melting temperature. Our results indicate that supercooling is pervasive. In general, supercooling is greater in more concentrated solutions and with salts of Ca and Mg. Slowly cooled MgSO4, MgCl2, NaCl, and NaClO4 solutions investigated in this study typically supercool 5-15 °C below their eutectic temperature before crystallizing. The addition of soil to these salt solutions has a variable effect on supercooling. Relative to the pure salt solutions, supercooling decreases in MgSO4 soil-solutions, increases in MgCl2 soil-solutions, and is similar in NaCl and NaClO4 soil-solutions. Supercooling in MgSO4, MgCl2, NaCl, and NaClO4 solutions could marginally extend the duration of liquid water during relatively warm daytime temperatures in the martian summer. In contrast, we find that Mg(ClO4)2 and Ca(ClO4)2 solutions do not crystallize during slow cooling, but remain in a supercooled, liquid state until forming an amorphous glass near -120 °C. Even if soil is added to the solutions, a glass still forms during cooling. The large supercooling effect in Mg(ClO4)2 and Ca(ClO4)2 solutions has the potential to prevent water from freezing over diurnal and possibly annual cycles on Mars. Glasses are also potentially important for astrobiology because of their ability to preserve pristine cellular structures intact compared to solutions that crystallize.

Role of Absolute Humidity in the Inactivation of Influenza Viruses on Stainless Steel Surfaces at Elevated Temperatures ▿

PubMed Central

McDevitt, James; Rudnick, Stephen; First, Melvin; Spengler, John

2010-01-01

Influenza virus has been found to persist in the environment for hours to days, allowing for secondary transmission of influenza via inanimate objects known as fomites. We evaluated the efficacy of heat and moisture for the decontamination of surfaces for the purpose of preventing of the spread of influenza. Aqueous suspensions of influenza A virus were deposited onto stainless steel coupons, allowed to dry under ambient conditions, and exposed to temperatures of 55°C, 60°C, or 65°C and relative humidity (RH) of 25%, 50%, or 75% for up to 1 h. Quantitative virus assays were performed on the solution used to wash the viruses from these coupons, and results were compared with the solution used to wash coupons treated similarly but left under ambient conditions. Inactivation of influenza virus on surfaces increased with increasing temperature, RH, and exposure time. Reductions of greater than 5 logs of influenza virus on surfaces were achieved at temperatures of 60 and 65°C, exposure times of 30 and 60 min, and RH of 50 and 75%. Our data also suggest that absolute humidity is a better predictor of surface inactivation than RH and allows the prediction of survival using two parameters rather than three. Modest amounts of heat and adequate moisture can provide effective disinfection of surfaces while not harming surfaces, electrical systems, or mechanical components, leaving no harmful residues behind after treatment and requiring a relatively short amount of time. PMID:20435770

Response to “Comment on ‘General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation’” [Phys. Fluids 26, 119101 (2014)

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

Van Gorder, Robert A., E-mail: rav@knights.ucf.edu

2014-11-15

In R. A. Van Gorder, “General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation,” Phys. Fluids 26, 065105 (2014) I discussed properties of generalized vortex filaments exhibiting purely rotational motion under the low-temperature Svistunov model of the local induction approximation. Such solutions are stationary in terms of translational motion. In the Comment [N. Hietala, “Comment on ‘General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation’ [Phys. Fluids 26, 065105 (2014)],” Phys. Fluids 26, 119101 (2014)], the author criticizes my paper for not including translational motion (although it wasmore » clearly stated that the filament motion was assumed rotational). As it turns out, if one is interested in studying the geometric structure of solutions (which was the point of my paper), one obtains the needed qualitative results on the structure of such solutions by studying the purely rotational case. Nevertheless, in this Response I shall discuss the vortex filaments that have both rotational and translational motions. I then briefly discuss why one might want to study such generalized rotating filament solutions, in contrast to simple the standard helical or planar examples (which are really special cases). I also discuss how one can study the time evolution of filaments which exhibit more complicated dynamics than pure translation and rotation. Doing this, one can study non-stationary solutions which initially appear purely rotational and gradually display other dynamics as the filaments evolve.« less

Hemoglobin Dynamics in Red Blood Cells: Correlation to Body Temperature

PubMed Central

Stadler, A. M.; Digel, I.; Artmann, G. M.; Embs, J. P.; Zaccai, G.; Büldt, G.

2008-01-01

A transition in hemoglobin behavior at close to body temperature has been discovered recently by micropipette aspiration experiments on single red blood cells (RBCs) and circular dichroism spectroscopy on hemoglobin solutions. The transition temperature was directly correlated to the body temperatures of a variety of species. In an exploration of the molecular basis for the transition, we present neutron scattering measurements of the temperature dependence of hemoglobin dynamics in whole human RBCs in vivo. The data reveal a change in the geometry of internal protein motions at 36.9°C, at human body temperature. Above that temperature, amino acid side-chain motions occupy larger volumes than expected from normal temperature dependence, indicating partial unfolding of the protein. Global protein diffusion in RBCs was also measured and the findings compared favorably with theoretical predictions for short-time self-diffusion of noncharged hard-sphere colloids. The results demonstrated that changes in molecular dynamics in the picosecond time range and angstrom length scale might well be connected to a macroscopic effect on whole RBCs that occurs at body temperature. PMID:18708462

Hemoglobin dynamics in red blood cells: correlation to body temperature.

PubMed

Stadler, A M; Digel, I; Artmann, G M; Embs, J P; Zaccai, G; Büldt, G

2008-12-01

A transition in hemoglobin behavior at close to body temperature has been discovered recently by micropipette aspiration experiments on single red blood cells (RBCs) and circular dichroism spectroscopy on hemoglobin solutions. The transition temperature was directly correlated to the body temperatures of a variety of species. In an exploration of the molecular basis for the transition, we present neutron scattering measurements of the temperature dependence of hemoglobin dynamics in whole human RBCs in vivo. The data reveal a change in the geometry of internal protein motions at 36.9 degrees C, at human body temperature. Above that temperature, amino acid side-chain motions occupy larger volumes than expected from normal temperature dependence, indicating partial unfolding of the protein. Global protein diffusion in RBCs was also measured and the findings compared favorably with theoretical predictions for short-time self-diffusion of noncharged hard-sphere colloids. The results demonstrated that changes in molecular dynamics in the picosecond time range and angstrom length scale might well be connected to a macroscopic effect on whole RBCs that occurs at body temperature.

Sol-gel processing with inorganic metal salt precursors

DOEpatents

Hu, Zhong-Cheng

2004-10-19

Methods for sol-gel processing that generally involve mixing together an inorganic metal salt, water, and a water miscible alcohol or other organic solvent, at room temperature with a macromolecular dispersant material, such as hydroxypropyl cellulose (HPC) added. The resulting homogenous solution is incubated at a desired temperature and time to result in a desired product. The methods enable production of high quality sols and gels at lower temperatures than standard methods. The methods enable production of nanosize sols from inorganic metal salts. The methods offer sol-gel processing from inorganic metal salts.

Porous Ceramic Cures at Moderate Temperatures, Is Good Heat Insulator

NASA Technical Reports Server (NTRS)

Eubanks, Alfred G.; Hunkeler, Ronald E.

1965-01-01

The problem: To develop a foamed-in-place refractory material that would provide good thermal insulation, mechanical support, and vibration shielding for enclosed objects at temperatures up to 30000 F. The preparation of conventional foamed refractory materials required long curing times (as much as 48 hours) and high temperatures (at least 700 F), rendering such materials unusable for in-place potting of heat-sensitive components. The solution: A foamed ceramic material that has the requisite thermal insulation and strength, and also displays other properties that suggest a wide range of applications.

Effects of Shapes of Solute Molecules on Diffusion: A Study of Dependences on Solute Size, Solvent, and Temperature.

PubMed

Chan, T C; Li, H T; Li, K Y

2015-12-24

Diffusivities of basically linear, planar, and spherical solutes at infinite dilution in various solvents are studied to unravel the effects of solute shapes on diffusion. On the basis of the relationship between the reciprocal of diffusivity and the molecular volume of solute molecules with similar shape in a given solvent at constant temperature, the diffusivities of solutes of equal molecular volume but different shapes are evaluated and the effects due to different shapes of two equal-sized solute molecules on diffusion are determined. It is found that the effects are dependent on the size of the solute pairs studied. Evidence of the dependence of the solute-shape effects on solvent properties is also demonstrated and discussed. Here, some new diffusion data of aromatic compounds in methanol at different temperatures are reported. The result for methanol in this study indicates that the effects of solute shape on diffusivity are only weakly dependent on temperature.

A two-dimensional MHD global coronal model - Steady-state streamers

NASA Technical Reports Server (NTRS)

Wang, A.-H.; Wu, S. T.; Suess, S. T.; Poletto, G.

1992-01-01

A 2D, time-dependent, numerical, MHD model for the simulation of coronal streamers from the solar surface to 15 solar is presented. Three examples are given; for dipole, quadrupole and hexapole (Legendre polynomials P1, P2, and P3) initial field topologies. The computed properties are density, temperature, velocity, and magnetic field. The calculation is set up as an initial-boundary value problem wherein a relaxation in time produces the steady state solution. In addition to the properties of the solutions, their accuracy is discussed. Besides solutions for dipole, quadrupole, and hexapole geometries, the model use of realistic values for the density and Alfven speed while still meeting the requirement that the flow speed be super-Alfvenic at the outer boundary by extending the outer boundary to 15 solar radii.

Effect of urea on heat-induced gelation of bovine serum albumin (BSA) studied by rheology and small angle neutron scattering (SANS)

NASA Astrophysics Data System (ADS)

Nnyigide, Osita Sunday; Oh, Yuna; Song, Hyeong Yong; Park, Eun-kyoung; Choi, Soo-Hyung; Hyun, Kyu

2017-05-01

This paper reports the effects of urea on the heat-induced gelation of bovine serum albumin (BSA), which was studied by the tube inversion method, rheological measurements, and small-angle neutron scattering (SANS). An increase in the urea concentration accelerated the rate of gelation because the protein molecules have already been unfolded to some extent during sample preparation in the urea solution. In addition, the BSA solution in the presence of urea underwent a sol-gel-sol transition during the time sweep test at a constant temperature of 80oC. On the other hand, the BSA solution without urea turned into a hard and brittle gel that did not return to the solution state during isothermal heating at a constant temperature of 80oC. Aggregation and re-bonding of the denatured and unfolded protein chains led to gel formation. Urea added to the protein denatures its tertiary and secondary structures by simultaneously disrupting the hydrogen bonds, hydrophobic interactions, and altering the solvent properties. Furthermore, urea induces thermoreversible chemical interactions in BSA solutions leading to the formation of a gel with dynamic properties under these experimental conditions.

Uranium removal from aqueous solution by coir pith: equilibrium and kinetic studies.

PubMed

Parab, Harshala; Joshi, Shreeram; Shenoy, Niyoti; Verma, Rakesh; Lali, Arvind; Sudersanan, M

2005-07-01

Basic aspects of uranium adsorption by coir pith have been investigated by batch equilibration. The influence of different experimental parameters such as final solution pH, adsorbent dosage, sorption time, temperature and various concentrations of uranium on uptake were evaluated. Maximum uranium adsorption was observed in the pH range 4.0-6.0. The Freundlich and Langmuir adsorption models were used for the mathematical description of the adsorption equilibrium. The equilibrium data fitted well to both the equilibrium models in the studied concentration range of uranium (200-800 mg/l) and temperatures (305-336 K). The coir pith exhibited the highest uptake capacity for uranium at 317 K, at the final solution pH value of 4.3 and at the initial uranium concentration of 800 mg/l. The kinetics of the adsorption process followed a second-order adsorption. The adsorbent used proved to be suitable for removal of uranium from aqueous solutions. 0.2 N HCl was effective in uranium desorption. The results indicated that the naturally abundant coir pith of otherwise nuisance value exhibited considerable potential for application in removal of uranium from aqueous solution.

Seasonal multiphase equilibria in the atmospheres of Titan and Pluto

NASA Astrophysics Data System (ADS)

Tan, S. P.; Kargel, J. S.

2017-12-01

At the extremely low temperatures in Titan's upper troposphere and on Pluto's surface, the atmospheres as a whole are subject to freeze into solid solutions, not pure ices. The presence of the solid phases introduces conditions with rich phase equilibria upon seasonal changes, even if the temperature undergoes only small changes. For the first time, the profile of atmospheric methane in Titan's troposphere will be reproduced complete with the solid solutions. This means that the freezing point, i.e. the altitude where the first solid phase appears, is determined. The seasonal change will also be evaluated both at the equator and the northern polar region. For Pluto, also for the first time, the seasonal solid-vapor equilibria will be evaluated. The fate of the two solid phases, the methane-rich and carbon-monoxide-rich solid solutions, will be analyzed upon temperature and pressure changes. Such investigations are enabled by the development of a molecular-based thermodynamic model for cryogenic chemical systems, referred to as CRYOCHEM, which includes solid solutions in its phase-equilibria calculations. The atmospheres of Titan and Pluto are modeled as ternary gas mixtures: nitrogen-methane-ethane and nitrogen-methane-carbon monoxide, respectively. Calculations using CRYOCHEM can provide us with compositions not only in two-phase equilibria, but also that in three-phase equilibria. Densities of all phases involved will also be calculated. For Titan, density inversion between liquid and solid phases will be identified and presented. In the inversion, the density of solid phase is less than that in the liquid phase. The method and results of this work will be useful for further investigations and modeling on the atmospheres of Titan, Pluto, and other bodies with similar conditions in the Solar System and beyond.

Decalcification by ascorbic acid for immuno- and affinohistochemical techniques on the inner ear.

PubMed

Merchán-Pérez, A; Gil-Loyzaga, P; Bartolomé, M V; Remezal, M; Fernández, P; Rodríguez, T

1999-08-01

An ascorbic acid decalcifying solution was applied to immuno- and affinohistochemical studies on the inner ear. Rat inner ears fixed in 4% paraformaldehyde in PBS or in 2% acetic acid in ethanol solutions were adequately decalcified in an ascorbic acid solution, at a temperature of 4 degrees C. The decalcifying solution was prepared with 1% ascorbic acid and 0.84% sodium chloride in distilled water (pH 2.5-2.6). The decalcification time was in a direct relationship to the specimen calcification. In this study, two neuroactive substances (gamma-aminobutyric acid and calcitonin gene-related peptide), neurofilaments, and the galectine endogenous lectin were successfully detected immunohistochemically.

Gelation kinetics of gelatin using particle tracking microrheology

NASA Astrophysics Data System (ADS)

Hardcastle, Joseph; Bansil, Rama

2012-02-01

Previous studies with gelatin have observed four distinct stages during the physical gelation process [Normand et al. Macromolecules, 2000, 33, 1063]. In this presentation we report measurements of microrheology in an effort to examine the time evolution of the gel on short length scales and time scales. By tracking latex particles in gelatin solution at different temperatures we can follow the microrheological changes and kinetics of the gelation process. Using the generalized Stokes-Einstein relation viscoelastic properties of these quasi-static gel states the evolution of the storage and loss moduli, G' and G'', are examined as functions of both time and temperature. The data show that both G' and G'' exhibit power law scaling versus frequency with the same exponent. The temperature and concentration dependence of the frequency at which the system crosses over from viscous to elastic behavior will be presented.

Thermosetting gels with modulated gelation temperature for ophthalmic use: the rheological and gamma scintigraphic studies.

PubMed

Wei, Gang; Xu, Hui; Ding, Ping Tian; Li, San Ming; Zheng, Jun Min

2002-09-18

For ophthalmic drug delivery, Pluronic F127 solutions have a phase transition temperature too low for them to be instilled into the eye at room temperature. Refrigerator storage is usually required to make administration easier, whereas the potential irritation of cold to the sensitive ocular tissues may result in poor topical bioavailability. The purpose of this study is to develop a thermosetting gel with a suitable phase transition temperature by combining Pluronic analogs and to examine the influence of incorporating mucoadhesive polysaccharide, sodium hyaluronate (HA-Na), on the ocular retention of the gel. Dynamic rheological method and single photon emission computing tomography (SPECT) technique were used to ex/in vivo evaluate the thermosetting gels, respectively. An optimized formulation containing 21% F127 and 10% F68 increased the phase transition temperature by 9 degrees C as evaluated by elasticity modulus compared to that of individual 21% F127 solution. Rheological behaviors of the Pluronic solutions showed that the combined Pluronic formulation was free flowing liquid below 25 degrees C and converted to a firm gel under the physiological condition. Furthermore, this formulation possessed the highest viscosity both before and after tear dilution at 35 degrees C. Gamma scintigraphic data demonstrated that the clearance of the thermosetting gel labeled with 99mTc-DTPA was significantly delayed with respect to the phosphate buffered solution, and at least a threefold increase of the corneal residence time was achieved. However, no further improvement in the ocular retention was observed when adding HA-Na into the thermosetting gel due to the substantially decreased gel strength. Copyright 2002 Elsevier Science B.V.

Low-temperature solution processing of palladium/palladium oxide films and their pH sensing performance.

PubMed

Qin, Yiheng; Alam, Arif U; Pan, Si; Howlader, Matiar M R; Ghosh, Raja; Selvaganapathy, P Ravi; Wu, Yiliang; Deen, M Jamal

2016-01-01

Highly sensitive, easy-to-fabricate, and low-cost pH sensors with small dimensions are required to monitor human bodily fluids, drinking water quality and chemical/biological processes. In this study, a low-temperature, solution-based process is developed to prepare palladium/palladium oxide (Pd/PdO) thin films for pH sensing. A precursor solution for Pd is spin coated onto pre-cleaned glass substrates and annealed at low temperature to generate Pd and PdO. The percentages of PdO at the surface and in the bulk of the electrodes are correlated to their sensing performance, which was studied by using the X-ray photoelectron spectroscope. Large amounts of PdO introduced by prolonged annealing improve the electrode's sensitivity and long-term stability. Atomic force microscopy study showed that the low-temperature annealing results in a smooth electrode surface, which contributes to a fast response. Nano-voids at the electrode surfaces were observed by scanning electron microscope, indicating a reason for the long-term degradation of the pH sensitivity. Using the optimized annealing parameters of 200°C for 48 h, a linear pH response with sensitivity of 64.71±0.56 mV/pH is obtained for pH between 2 and 12. These electrodes show a response time shorter than 18 s, hysteresis less than 8 mV and stability over 60 days. High reproducibility in the sensing performance is achieved. This low-temperature solution-processed sensing electrode shows the potential for the development of pH sensing systems on flexible substrates over a large area at low cost without using vacuum equipment. Copyright © 2015 Elsevier B.V. All rights reserved.

Study of aniline polymerization reactions through the particle size formation in acidic and neutral medium

NASA Astrophysics Data System (ADS)

Aribowo, Slamet; Hafizah, Mas Ayu Elita; Manaf, Azwar; Andreas

2018-04-01

In the present paper, we reported particle size kinetic studies on the conducting polyaniline (PANI) which synthesized through a chemical oxidative polymerization technique from aniline monomer. PANI was prepared using ammonium persulfate (APS) as oxidizing agent which carried out in acidic and neutral medium at various batch temperatures of respectively 20, 30 and 50 °C. From the studies, it was noticed that the complete polymerization reaction progressed within 480 minutes duration time. The pH of the solution during reaction kinetic reached values 0.8 - to 1.2 in acidic media, while in the neutral media the pH value reached values 3.8 - 4.9. The batch temperature controlled the polymerization reaction in which the reaction progressing, which followed by the temperature rise of solution above the batch temperature before settled down to the initial temperature. An increment in the batch temperature gave highest rise in the solution temperature for the two media which cannot be more than 50 °C. The final product of polymerization reaction was PANI confirmed by Fourier Transform Infra-Red (FTIR) spectrophotometer for molecule structure identification. The averages particle size of PANI which carried out in the two different media is evidently similar in the range 30 - 40 μm and insensitive to the batch temperature. However, the particle size of PANI which obtained from the polymerization reaction at a batch temperature of 50 °C under acidic condition reached ˜53.1 μm at the tip of the propagation stage which started in the first 5 minutes. The size is obviously being the largest among the batch temperatures. Whereas, under neutral condition the particle size is much larger which reached the size 135 μm at the batch temperature of 20 °C. It is concluded that the particle size formation during the polymerization reaction being one of the important parameter to determine particle growing of polymer which indicated the reaction kinetics mechanism of synthesize polyaniline.

Response time for multilayered platinum resistance thermometers

NASA Technical Reports Server (NTRS)

Pandey, D. K.; Ash, R. L.

1985-01-01

Response time constants for several multilayered temperature transducers were determined numerically by using Martin Marietta's MITAS software package which is available at NASA Langley Research Center. Present results were found in close agreement with the solutions reported in the literature, thus, the capability of MITAS was justified. On the basis of experiences gained, the MITAS is recommended for use in predicting the response time constants of sensors by an in-situ technique.

Stability study of carboplatin infusion solutions in 0.9% sodium chloride in polyvinyl chloride bags.

PubMed

Myers, Alan L; Zhang, Yang-Ping; Kawedia, Jitesh D; Trinh, Van A; Tran, Huyentran; Smith, Judith A; Kramer, Mark A

2016-02-01

Carboplatin is a platinum-containing compound with efficacy against various malignancies. The physico-chemical stability of carboplatin in dextrose 5% water (D5W) has been thoroughly studied; however, there is a paucity of stability data in clinically relevant 0.9% sodium chloride infusion solutions. The manufacturer's limited stability data in sodium chloride solutions hampers the flexibility of carboplatin usage in oncology patients. Hence, the purpose of this study is to determine the physical and chemical stability of carboplatin-sodium chloride intravenous solutions under different storage conditions. The physico-chemical stability of 0.5 mg/mL, 2.0 mg/mL, and 4.0 mg/mL carboplatin-sodium chloride solutions prepared in polyvinyl chloride bags was determined following storage at room temperature under ambient fluorescent light and under refrigeration in the dark. Concentrations of carboplatin were measured at predetermined time points up to seven days using a stability-indicating high-performance liquid chromatography method. All tested solutions were found physically stable for at least seven days. The greatest chemical stability was observed under refrigerated storage conditions. At 4℃, all tested solutions were found chemically stable for at least seven days, with nominal losses of ≤6%. Following storage at room temperature exposed to normal fluorescent light, the chemical stability of 0.5 mg/mL, 2.0 mg/mL, and 4.0 mg/mL solutions was three days, five days, and seven days, respectively. The extended physico-chemical stability of carboplatin prepared in sodium chloride reported herein permits advance preparation of these admixtures, facilitating pharmacy utility and operations. Since no antibacterial preservative is contained within these carboplatin solutions, we recommend storage, when prepared under specified aseptic conditions, no greater than 24 h at room temperature or three days under refrigeration. © The Author(s) 2014.

Intramuscular temperature modulates glutamate-evoked masseter muscle pain intensity in humans.

PubMed

Sato, Hitoshi; Castrillon, Eduardo E; Cairns, Brian E; Bendixen, Karina H; Wang, Kelun; Nakagawa, Taneaki; Wajima, Koichi; Svensson, Peter

2015-01-01

To determine whether glutamate-evoked jaw muscle pain is altered by the temperature of the solution injected. Sixteen healthy volunteers participated and received injections of hot (48°C), neutral (36°C), or cold (3°C) solutions (0.5 mL) of glutamate or isotonic saline into the masseter muscle. Pain intensity was assessed with an electronic visual analog scale (eVAS). Numeric rating scale (NRS) scores of unpleasantness and temperature perception, pain-drawing areas, and pressure pain thresholds (PPTs) were also measured. Participants filled out the McGill Pain Questionnaire (MPQ). Two-way or three-way repeated measures ANOVA were used for data analyses. Injection of hot glutamate and cold glutamate solutions significantly increased and decreased, respectively, the peak pain intensity compared with injection of neutral glutamate solution. The duration of glutamate-evoked pain was significantly longer when hot glutamate was injected than when cold glutamate was injected. No significant effect of temperature on pain intensity was observed when isotonic saline was injected. No effect of solution temperature was detected on unpleasantness, heat perception, cold perception, area of pain drawings, or PPTs. There was a significantly greater use of the "numb" term in the MPQ to describe the injection of cold solutions compared to the injection of both neutral and hot solutions. Glutamate-evoked jaw muscle pain was significantly altered by the temperature of the injection solution. Although temperature perception in the jaw muscle is poor, pain intensity is increased when the muscle tissue temperature is elevated.

Stability analysis of implicit time discretizations for the Compton-scattering Fokker-Planck equation

NASA Astrophysics Data System (ADS)

Densmore, Jeffery D.; Warsa, James S.; Lowrie, Robert B.; Morel, Jim E.

2009-09-01

The Fokker-Planck equation is a widely used approximation for modeling the Compton scattering of photons in high energy density applications. In this paper, we perform a stability analysis of three implicit time discretizations for the Compton-Scattering Fokker-Planck equation. Specifically, we examine (i) a Semi-Implicit (SI) scheme that employs backward-Euler differencing but evaluates temperature-dependent coefficients at their beginning-of-time-step values, (ii) a Fully Implicit (FI) discretization that instead evaluates temperature-dependent coefficients at their end-of-time-step values, and (iii) a Linearized Implicit (LI) scheme, which is developed by linearizing the temperature dependence of the FI discretization within each time step. Our stability analysis shows that the FI and LI schemes are unconditionally stable and cannot generate oscillatory solutions regardless of time-step size, whereas the SI discretization can suffer from instabilities and nonphysical oscillations for sufficiently large time steps. With the results of this analysis, we present time-step limits for the SI scheme that prevent undesirable behavior. We test the validity of our stability analysis and time-step limits with a set of numerical examples.

A numerical analysis of phase-change problems including natural convection

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

Cao, Y.; Faghri, A.

1990-08-01

Fixed grid solutions for phase-change problems remove the need to satisfy conditions at the phase-change front and can be easily extended to multidimensional problems. The two most important and widely used methods are enthalpy methods and temperature-based equivalent heat capacity methods. Both methods in this group have advantages and disadvantages. Enthalpy methods (Shamsundar and Sparrow, 1975; Voller and Prakash, 1987; Cao et al., 1989) are flexible and can handle phase-change problems occurring both at a single temperature and over a temperature range. The drawback of this method is that although the predicted temperature distributions and melting fronts are reasonable, themore » predicted time history of the temperature at a typical grid point may have some oscillations. The temperature-based fixed grid methods (Morgan, 1981; Hsiao and Chung, 1984) have no such time history problems and are more convenient with conjugate problems involving an adjacent wall, but have to deal with the severe nonlinearity of the governing equations when the phase-change temperature range is small. In this paper, a new temperature-based fixed-grid formulation is proposed, and the reason that the original equivalent heat capacity model is subject to such restrictions on the time step, mesh size, and the phase-change temperature range will also be discussed.« less

Solute induced relaxation in glassy polymers: Experimental measurements and nonequilibrium thermodynamic model

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

Minelli, Matteo; Doghieri, Ferruccio

2014-05-15

Data for kinetics of mass uptake from vapor sorption experiments in thin glassy polymer samples are here interpreted in terms of relaxation times for volume dilation. To this result, both models from non-equilibrium thermodynamics and from mechanics of volume relaxation contribute. Different kind of sorption experiments have been considered in order to facilitate the direct comparison between kinetics of solute induced volume dilation and corresponding data from process driven by pressure or temperature jumps.

Improved retroreflection method for measuring the refractive index of liquids.

PubMed

Shao, Duo; Tian, Linghao; Chen, Jingfei; Chen, Xianfeng

2010-06-01

We propose a new method for measuring the refractive index of liquids with high precision; the method is based on use of the optical fiber end face. As an example, we investigated the refractive index of sugar solution under varying conditions tens of times. The results show that this method has the advantage of higher stability and repeatability. The concentration and the temperature-dependent refractive index of the sugar solution is also experimentally studied.

Carbon nanotube-sensor-integrated microfluidic platform for real-time chemical concentration detection.

PubMed

Yang, Li; Li, Minglin; Qu, Yanli; Dong, Zaili; Li, Wen J

2009-09-01

This paper presents the development of a chemical sensor employing electronic-grade carbon nanotubes (EG-CNTs) as the active sensing element for sodium hypochlorite detection. The sensor, integrated in a PDMS-glass microfluidic chamber, was fabricated by bulk aligning of EG-CNTs between gold microelectrode pairs using dielectrophoretic technique. Upon exposure to sodium hypochlorite solution, the characteristics of the carbon nanotube chemical sensor were investigated at room temperature under constant current mode. The sensor exhibited responsivity, which fits a linear logarithmic dependence on concentration in the range of 1/32 to 8 ppm, a detection limit lower than 5 ppb, while saturating at 16 ppm. The typical response time of the sensor at room temperature is on the order of minutes and the recovery time is a few hours. In particular, the sensor showed an obvious sensitivity to the volume of detected solution. It was found that the activation power of the sensor was extremely low, i.e. in the range of nanowatts. These results indicate great potential of EG-CNT for advanced nanosensors with superior sensitivity, ultra-low power consumption, and less fabrication complexity.

The dynamics of nucleation and growth of a particle in the ternary alloy melt with anisotropic surface tension.

PubMed

Chen, Ming-Wen; Li, Lin-Yan; Guo, Hui-Min

2017-08-28

The dynamics of nucleation and growth of a particle affected by anisotropic surface tension in the ternary alloy melt is studied. The uniformly valid asymptotic solution for temperature field, concentration field, and interface evolution of nucleation and particle growth is obtained by means of the multiple variable expansion method. The asymptotic solution reveals the critical radius of nucleation in the ternary alloy melt and an inward melting mechanism of the particle induced by the anisotropic effect of surface tension. The critical radius of nucleation is dependent on isotropic surface tension, temperature undercooling, and constitutional undercooling in the ternary alloy melt, and the solute diffusion melt decreases the critical radius of nucleation. Immediately after a nucleus forms in the initial stage of solidification, the anisotropic effect of surface tension makes some parts of its interface grow inward while some parts grow outward. Until the inward melting attains a certain distance (which is defined as "the melting depth"), these parts of interface start to grow outward with other parts. The interface of the particle evolves into an ear-like deformation, whose inner diameter may be less than two times the critical radius of nucleation within a short time in the initial stage of solidification. The solute diffusion in the ternary alloy melt decreases the effect of anisotropic surface tension on the interface deformation.

Characterization of alloy 718 subjected to different thermomechanical treatments

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

Silva, Chinthaka; Song, Miao; Leonard, Keith

2017-03-11

Chemical phase and microstructural investigations of alloy 718 solution-annealed and age-hardened were performed in this study. We focused on the effects of solution annealing temperature, aging temperature and holding time, and the amount of intermediate cold work on the alloy. We also studied the formation of secondary phases such as γ’-phase, γ”-phase, and δ-phase, grain sizes, and any deformations of the microstructure with respect to the processed conditions. Statistics such as size and number densities of these precipitates with respect to the processing conditions were evaluated and a discussion on optimum conditions in obtaining finer and higher density of γ’-more » and γ”-phase precipitates is also presented.« less

A simple and low-cost chip bonding solution for high pressure, high temperature and biological applications.

PubMed

Serra, M; Pereiro, I; Yamada, A; Viovy, J-L; Descroix, S; Ferraro, D

2017-02-14

The sealing of microfluidic devices remains a complex and time-consuming process requiring specific equipment and protocols: a universal method is thus highly desirable. We propose here the use of a commercially available sealing tape as a robust, versatile, reversible solution, compatible with cell and molecular biology protocols, and requiring only the application of manually achievable pressures. The performance of the seal was tested with regards to the most commonly used chip materials. For most materials, the bonding resisted 5 bars at room temperature and 1 bar at 95 °C. This method should find numerous uses, ranging from fast prototyping in the laboratory to implementation in low technology environments or industrial production.

Dynamics of Re(2,2'-bipyridine)(CO)3Cl MLCT formation and decay after picosecond pulsed X-ray excitation and femtosecond UV excitation.

PubMed

Zhao, Liyan; Odaka, Hideho; Ono, Hiroshi; Kajimoto, Shinji; Hatanaka, Koji; Hobley, Jonathan; Fukumura, Hiroshi

2005-01-01

The dynamics of Re(2,2'-bipyridine)(CO)3Cl MLCT state formation and decay were determined after femtosecond UV laser excitation and picosecond pulsed X-ray excitation, in an N,N-dimethylformamide (DMF) solution as well as in its solid form. At room temperature, after UV excitation, this MLCT excited state emits both in DMF solution and in the solid form. Transient absorption spectra were measured in solution at various delay times following excitation by a 160 fs, 390 nm laser pulse. There was a prompt absorption increase at around 460 nm occurring within the pump probe convolution (<1 ps), which was assigned to the formation of the 3MLCT state. This transient absorbance was constant over 100 ps. In contrast to the solution state, in the solid state, the emission maximum slightly red-shifts with increasing time after laser excitation. In both solid and solution the emission rises within the system response time. The solid sample exhibited a 1.4 ns emission decay that was not observed for the solution sample. The emission rise from a solid sample after 20 ps pulsed X-ray excitation was significantly slower than the system's time resolution. It is proposed that kinetically energetic electrons are ejected following X-ray induced ionisation, creating ionised tracks in which energetic cations and electrons take time to recombine yielding delayed 3MLCT states that emit.

Aqueous route to facile, efficient and functional silica coating of metal nanoparticles at room temperature

NASA Astrophysics Data System (ADS)

Shah, Kwok Wei; Sreethawong, Thammanoon; Liu, Shu-Hua; Zhang, Shuang-Yuan; Tan, Li Sirh; Han, Ming-Yong

2014-09-01

Various metal (Ag, Au, and Pt)@thiol-functionalized silica (SiO2-SH) nanoparticles (NPs) are successfully prepared at room temperature by a facile, efficient, functional, universal and scalable coating process in alcohol-free aqueous solution using pre-hydrolyzed 3-(mercaptopropyl)trimethoxysilane (MPTMS). The controlled pre-hydrolysis of the silane precursor in water and the consecutive condensation processes are the key to achieve the effective and uniform silica coating on metal NPs in aqueous solution. The thickness of the silica shell is tuned by simply varying the coating time. The silica shell can act as an effective protecting layer for Ag NPs in Ag@SiO2-SH NPs under conditions for silica coating in aqueous solution; however, it leads to a directional dissolution of Ag NPs in a more strongly basic ammonia solution. The environmentally friendly silica coating process in water is also applied to prepare highly surface-enhanced Raman scattering (SERS)-active Ag@SiO2-SH NPs with different types of Raman molecules for highly sensitive SERS-based applications in various fields.Various metal (Ag, Au, and Pt)@thiol-functionalized silica (SiO2-SH) nanoparticles (NPs) are successfully prepared at room temperature by a facile, efficient, functional, universal and scalable coating process in alcohol-free aqueous solution using pre-hydrolyzed 3-(mercaptopropyl)trimethoxysilane (MPTMS). The controlled pre-hydrolysis of the silane precursor in water and the consecutive condensation processes are the key to achieve the effective and uniform silica coating on metal NPs in aqueous solution. The thickness of the silica shell is tuned by simply varying the coating time. The silica shell can act as an effective protecting layer for Ag NPs in Ag@SiO2-SH NPs under conditions for silica coating in aqueous solution; however, it leads to a directional dissolution of Ag NPs in a more strongly basic ammonia solution. The environmentally friendly silica coating process in water is also applied to prepare highly surface-enhanced Raman scattering (SERS)-active Ag@SiO2-SH NPs with different types of Raman molecules for highly sensitive SERS-based applications in various fields. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03306j

Experimental and numerical investigation of a packed-bed thermal energy storage device

NASA Astrophysics Data System (ADS)

Yang, Bei; Wang, Yan; Bai, Fengwu; Wang, Zhifeng

2017-06-01

This paper presents a pilot-scale setup built to study a packed bed thermal energy storage device based on ceramic balls randomly poured into a cylindrical tank while using air as heat transfer fluid. Temperature distribution of ceramic balls throughout the packed bed is investigated both experimentally and numerically. Method of characteristic is adopted to improve the numerical computing efficiency, and mesh independence is verified to guarantee the accuracy of numerical solutions and the economy of computing time cost at the same time. Temperature in tests is as high as over 600 °C, and modeling prediction shows good agreements with experimental results under various testing conditions when heat loss is included and thermal properties of air are considered as temperature dependent.

Transformation process for production of ultrahigh carbon steels and new alloys

DOEpatents

Strum, M.J.; Goldberg, A.; Sherby, O.D.; Landingham, R.L.

1995-08-29

Ultrahigh carbon steels with superplastic properties are produced by heating a steel containing ferrite and carbide phases to a soaking temperature approximately 50 C above the A{sub 1} transformation temperature, soaking the steel above the A{sub 1} temperature for a sufficient time that the major portion of the carbides dissolve into the austenite matrix, and then cooling the steel in a controlled manner within predetermined limits of cooling rate or transformation temperature, to obtain a steel having substantially spheroidal carbides. New alloy compositions contain aluminum and solute additions which promote the formation of a fine grain size and improve the resistance of the carbides to coarsening at the forming temperature. 9 figs.

Transformation process for production of ultrahigh carbon steels and new alloys

DOEpatents

Strum, Michael J.; Goldberg, Alfred; Sherby, Oleg D.; Landingham, Richard L.

1995-01-01

Ultrahigh carbon steels with superplastic properties are produced by heating a steel containing ferrite and carbide phases to a soaking temperature approximately 50.degree. C. above the A.sub.1 transformation temperature, soaking the steel above the A.sub.1 temperature for a sufficient time that the major portion of the carbides dissolve into the austenite matrix, and then cooling the steel in a controlled manner within predetermined limits of cooling rate or transformation temperature, to obtain a steel having substantially spheroidal carbides. New alloy compositions contain aluminum and solute additions which promote the formation of a fine grain size and improve the resistance of the carbides to coarsening at the forming temperature.

Study of the temperature configuration of parallel tempering for the traveling salesman problem

NASA Astrophysics Data System (ADS)

Hasegawa, Manabu

The effective temperature configuration of parallel tempering (PT) in finite-time optimization is studied for the solution of the traveling salesman problem. An experimental analysis is conducted to decide the relative importance of the two characteristic temperatures, the specific-heat-peak temperature referred to in the general guidelines and the effective intermediate temperature identified in the recent study on simulated annealing (SA). The results show that the operation near the former has no notable significance contrary to the conventional belief but that the operation near the latter plays a crucial role in fulfilling the optimization function of PT. The method shares the same origin of effectiveness with the SA and SA-related algorithms.

Molecular weight between entanglements for κ- and ι-carrageenans in an ionic liquid.

PubMed

Horinaka, Jun-ichi; Urabayashi, Yuhei; Wang, Xiaochen; Takigawa, Toshikazu

2014-08-01

The molecular weight between entanglements (Me) for κ- and ι-carrageenans, sulfated galactans, was examined in concentrated solutions using an ionic liquid 1-butyl-3-methylimidazolium acetate as a solvent. The dynamic viscoelasticity data for the solutions measured at different temperatures were overlapped according to the time-temperature superposition principle, and the obtained master curves exhibited the flow and rubbery plateau zones, being typical of concentrated polymer solutions having entanglement coupling. The values of Me for κ- and ι-carrageenans in the solutions were determined from the plateau moduli. Then the values of Me in the molten state (Me,melt) estimated as a material constant to be 6.6×10(3) and 7.2×10(3), respectively. The close values of Me,melt for κ- and ι-carrageenans indicate that 4-sulfate group of ι-carrageenan are not so influential for the entanglement network. Compared with agarose, a non-sulfate galactan, carrageenans have larger values of average spacing between entanglements. Copyright © 2014 Elsevier B.V. All rights reserved.

Utilizing Temperature and Resistivity Data as a Way to Characterize Water and Solute Movement and Groundwater-Surface Water Interaction in Variably Saturated Porous Media

NASA Astrophysics Data System (ADS)

Scotch, C.; Murgulet, D.; Hay, R.

2012-12-01

This study utilizes a multidisciplinary approach to better analyze the extent to which groundwater and surface water interact in the Oso Creek water shed of South Texas using temperature data, electrical resistivity and numerical modeling methods. The three primary objectives of this study are to: (1) identify primary areas of streambed groundwater-surface water interaction using temperature time series and resistivity soundings; (2) improve understanding of solute flow and groundwater, surface water, and sediment interaction in a semiarid, urban coastal area; (3) improve our understanding of groundwater contribution to contaminant transport and discharge to the bays and estuaries and ultimately the Gulf of Mexico. Temperature data was acquired over a one year period, using temperature loggers, from June 11, 2009 to May 18, 2010 at 15-minute intervals from 17 monitoring sites along Oso Creek and its tributaries. Each monitoring site consisted of 4 temperature loggers equally vertically spaced from the stream surface down to a depth of one meter. Furthermore, groundwater temperatures and water levels were collected from wells adjacent to the temperature monitoring sites. In order to fulfill the objectives of this study, existing hydrogeologic, stratigraphic, and other ancillary data are being integrated into a finite difference model developed using the USGS VS2DT software for the Oso Creek Watershed. The model will be calibrated using existing temperature and water level data and a resistivity component will also be added to assure accuracy of the model and temperature data by helping to identify varying lithologies and water conductivities. Compiling a time-series of temperature data and incorporating available hydrostratigraphic, geomorphologic and water level data will enable the development of a comprehensive database. This database is necessary to develop the detailed flow model that will enable an understanding of the extent of groundwater surface water interaction and their associated flow regimes.

Structural and low temperature dielectric studies on Pb0.8Bi0.2Fe0.6Nb0.4O3 multiferroic solid solution

NASA Astrophysics Data System (ADS)

Dadami, Sunanda T.; Matteppanvar, Shidaling; Shivaraja, I.; Rayaprol, Sudhindra; Deshapande, S. K.; Angadi, Basavaraj

2018-05-01

In this paper the structural and low temperature dielectric properties of Pb0.8Bi0.2Fe0.6Nb0.4O3 (PBFNO) multiferroic solid solution were reported. PBFNO multiferroic was synthesized by single step solid state reaction method. Calcination was carried out at 700 °/2hr with different sintering temperature (800 °C, 850 °C, 900 °C, 950 °C, 1000 °C and 1050 °C for 1 hr) and time duration (800 °C for 1 to 5 hr). Single phase was confirmed through room temperature (RT) X-ray Diffraction (XRD). It was found that sintering carried out at 800°C/3 hr gives single phase. Rietveld refined lattice parameters using monoclinic structure are: a = 5.6663(1) Å, b = 5.6694(1) Å, c = 4.0112(1) Å and β = 90.038(1)° with the average grain size as 2.987 µm. The dielectric properties studied over a wide range of frequency (100 Hz - 5 MHz) and temperature (133 K - 293 K). Dielectric constant and loss tangent exhibits frequency dispersion nature at low frequency region. AC conductivity increases with increase in temperature corresponds to negative temperature coefficient of resistance (NTCR) behaviour.

Ultrasonication as a potential tool to predict solute crystallization in freeze-concentrates.

PubMed

Ragoonanan, Vishard; Suryanarayanan, Raj

2014-06-01

We hypothesize that ultrasonication can accelerate solute crystallization in freeze-concentrates. Our objective is to demonstrate ultrasonication as a potential predictive tool for evaluating physical stability of excipients in frozen solutions. The crystallization tendencies of lyoprotectants (trehalose, sucrose), carboxylic acid buffers (citric, tartaric, malic, and acetic) and an amino acid buffer (histidine HCl) were studied. Aqueous solutions of buffers, lyoprotectants and mixtures of the two were cooled from room temperature to -20°C and sonicated to induce solute crystallization. The crystallized phases were identified by X-ray diffractometry (laboratory or synchrotron source). Sonication accelerated crystallization of trehalose dihydrate in frozen trehalose solutions. Sonication also enhanced solute crystallization in tartaric (200 mM; pH 5), citric (200 mM pH 4) and malic (200 mM; pH 4) acid buffers. At lower buffer concentrations, longer annealing times following sonication were required to facilitate solute crystallization. The time for crystallization of histidine HCl progressively increased as a function of sucrose concentration. The insonation period required to effect crystallization also increased with sucrose concentration. Sonication can substantially accelerate solute crystallization in the freeze-concentrate. Ultrasonication may be useful in assessing the crystallization tendency of formulation constituents used in long term frozen storage and freeze-drying.

Effects of heat treating PM Rene' 95 slightly below the gamma-prime solvus

NASA Technical Reports Server (NTRS)

Dreshfield, R. L.

1977-01-01

An investigation was performed on As-HIP Rene' 95 to obtain additional information on the variation of the amount of gamma-prime with solutioning temperatures near the gamma-prime solvus temperature and the resulting effects on tensile and stress rupture strengths of As-HIP Rene' 95. The amount of gamma-prime phase was found to increase at a rate of about 0.5% per degree Celsius as the temperature decreased from the solvus temperature to about 50 C below the gamma-prime solvus temperature. The change in the amount of gamma-prime phase with decreasing solutioning temperature was observed to be primarily associated with decreasing solubilities of Al+Ti+Nb and increasing solubility of Cr in the gamma phase. For As-HIP Rene' 95 solutioned at either 1107 or 1135 C and subsequently water-quenched and double aged for 4 hours at 815 C followed by 24 hours at 650 C, the higher solution temperature resulted in significantly greater yield strengths at room temperature and 650 C as well as a greater room-temperature ultimate strength. Also, longer stress rupture lives at 650 C were associated with the higher solution temperature.

An application for impedance spectroscopy in the characterisation of the glass transition during the lyophilization cycle: the example of a 10% w/v maltodextrin solution.

PubMed

Smith, Geoff; Arshad, Muhammad Sohail; Polygalov, Eugene; Ermolina, Irina

2013-11-01

Impedance spectroscopy has been used for the measurement of the glass transition of a 10 % maltodextrin solution contained within a glass vial, with externally attached electrodes. Features of the pseudo-relaxation process, associated with the composite impedance of the glass vial-solution assembly, were characterised by the peak amplitude, C(peak)(″), and peak frequency, f(peak), of the capacitance spectra and the equivalent circuit elements that model the impedance spectra (i.e. the solution resistance and solution capacitance) and monitored every 3 min during re-heating of the solution. The time derivatives of all four parameters studied provided a glass transition in close agreement with DSC measurements (-17 °C) and at a precision of ± 0.5 °C. The temperature dependencies of the solution resistance and peak frequency were then characterised with the Arrhenius and Vogel-Fulcher-Tammann fit functions, at temperatures below and above Tg, respectively. The energy of activation (below Tg) was estimated at ~20 kJ mol(-1), and the fragility index (If) of the glass forming liquid (above Tg) was estimated at 0.9. The significance of the fragility index to the development, optimisation and control of the freeze-drying cycle is highlighted. Copyright © 2013 Elsevier B.V. All rights reserved.

Ultrasound-assisted extraction of rare-earth elements from carbonatite rocks.

PubMed

Diehl, Lisarb O; Gatiboni, Thais L; Mello, Paola A; Muller, Edson I; Duarte, Fabio A; Flores, Erico M M

2018-01-01

In view of the increasing demand for rare-earth elements (REE) in many areas of high technology, alternative methods for the extraction of these elements have been developed. In this work, a process based on the use of ultrasound for the extraction of REE from carbonatite (an igneous rock) is proposed to avoid the use of concentrated reagents, high temperature and excessive extraction time. In this pioneer work for REE extraction from carbonatite rocks in a preliminary investigation, ultrasonic baths, cup horn systems or ultrasound probes operating at different frequencies and power were evaluated. In addition, the power released to the extraction medium and the ultrasound amplitude were also investigated and the temperature and carbonatite mass/volume of extraction solution ratio were optimized to 70°C and 20mg/mL, respectively. Better extraction efficiencies (82%) were obtained employing an ultrasound probe operating at 20kHz for 15min, ultrasound amplitude of 40% (692Wdm -3 ) and using a diluted extraction solution (3% v/v HNO 3 +2% v/v HCl). It is important to mention that high extraction efficiency was obtained even using a diluted acid mixture and relatively low temperature in comparison to conventional extraction methods for REE. A comparison of results with those obtained by mechanical stirring (500rpm) using the same conditions (time, temperature and extraction solution) was carried out, showing that the use of ultrasound increased the extraction efficiency up to 35%. Therefore, the proposed ultrasound-assisted procedure can be considered as a suitable alternative for high efficiency extraction of REE from carbonatite rocks. Copyright © 2017 Elsevier B.V. All rights reserved.

Rotational dynamics of trehalose in aqueous solutions studied by depolarized light scattering

NASA Astrophysics Data System (ADS)

Gallina, M. E.; Comez, L.; Morresi, A.; Paolantoni, M.; Perticaroli, S.; Sassi, P.; Fioretto, D.

2010-06-01

High resolution depolarized light scattering spectra, extended from 0.5 to 2×104 GHz by the combined used of a dispersive and an interferometric setup, give evidence of separated solute and solvent dynamics in diluted trehalose aqueous solutions. The slow relaxation process, located in the gigahertz frequency region, is analyzed as a function of temperature and concentration and assigned to the rotational diffusion of the sugar molecule. The results are discussed in comparison with the data obtained on glucose solutions and they are used to clarify the molecular origin of some among the several relaxation processes reported in literature for oligosaccharides solutions. The concentration dependence of relaxation time and of shear viscosity are also discussed, suggesting that the main effect of carbohydrate molecules on the structural relaxation of diluted aqueous solutions is the perturbation induced on the dynamics of the first hydration shell of each solute molecule.

Size effect, critical resolved shear stress, stacking fault energy, and solid solution strengthening in the CrMnFeCoNi high-entropy alloy.

PubMed

Okamoto, Norihiko L; Fujimoto, Shu; Kambara, Yuki; Kawamura, Marino; Chen, Zhenghao M T; Matsunoshita, Hirotaka; Tanaka, Katsushi; Inui, Haruyuki; George, Easo P

2016-10-24

High-entropy alloys (HEAs) comprise a novel class of scientifically and technologically interesting materials. Among these, equatomic CrMnFeCoNi with the face-centered cubic (FCC) structure is noteworthy because its ductility and strength increase with decreasing temperature while maintaining outstanding fracture toughness at cryogenic temperatures. Here we report for the first time by single-crystal micropillar compression that its bulk room temperature critical resolved shear stress (CRSS) is ~33-43 MPa, ~10 times higher than that of pure nickel. CRSS depends on pillar size with an inverse power-law scaling exponent of -0.63 independent of orientation. Planar ½ < 110 > {111} dislocations dissociate into Shockley partials whose separations range from ~3.5-4.5 nm near the screw orientation to ~5-8 nm near the edge, yielding a stacking fault energy of 30 ± 5 mJ/m 2 . Dislocations are smoothly curved without any preferred line orientation indicating no significant anisotropy in mobilities of edge and screw segments. The shear-modulus-normalized CRSS of the HEA is not exceptionally high compared to those of certain concentrated binary FCC solid solutions. Its rough magnitude calculated using the Fleischer/Labusch models corresponds to that of a hypothetical binary with the elastic constants of our HEA, solute concentrations of 20-50 at.%, and atomic size misfit of ~4%.

Size effect, critical resolved shear stress, stacking fault energy, and solid solution strengthening in the CrMnFeCoNi high-entropy alloy

PubMed Central

Okamoto, Norihiko L.; Fujimoto, Shu; Kambara, Yuki; Kawamura, Marino; Chen, Zhenghao M. T.; Matsunoshita, Hirotaka; Tanaka, Katsushi; Inui, Haruyuki; George, Easo P.

2016-01-01

High-entropy alloys (HEAs) comprise a novel class of scientifically and technologically interesting materials. Among these, equatomic CrMnFeCoNi with the face-centered cubic (FCC) structure is noteworthy because its ductility and strength increase with decreasing temperature while maintaining outstanding fracture toughness at cryogenic temperatures. Here we report for the first time by single-crystal micropillar compression that its bulk room temperature critical resolved shear stress (CRSS) is ~33–43 MPa, ~10 times higher than that of pure nickel. CRSS depends on pillar size with an inverse power-law scaling exponent of –0.63 independent of orientation. Planar ½ < 110 > {111} dislocations dissociate into Shockley partials whose separations range from ~3.5–4.5 nm near the screw orientation to ~5–8 nm near the edge, yielding a stacking fault energy of 30 ± 5 mJ/m2. Dislocations are smoothly curved without any preferred line orientation indicating no significant anisotropy in mobilities of edge and screw segments. The shear-modulus-normalized CRSS of the HEA is not exceptionally high compared to those of certain concentrated binary FCC solid solutions. Its rough magnitude calculated using the Fleischer/Labusch models corresponds to that of a hypothetical binary with the elastic constants of our HEA, solute concentrations of 20–50 at.%, and atomic size misfit of ~4%. PMID:27775026

Complete Fiber/Copper Cable Solution for Long-Term Temperature and Pressure Measurement in Supercritical Reservoirs and EGS Wells

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

Pastouret, Alan; Gooijer, Frans; Overton, Bob

High Temperature insulated wire and optical fiber cable is a key enabling technology for the Geothermal Technologies Program (GTP). Without insulated electrical wires and optical fiber, downhole temperature and pressure sensors, flow meters and gauges cannot communicate with the surface. Unfortunately, there are currently no insulated electrical wire or fiber cable constructions capable of surviving for extended periods of deployment in a geothermal well (240-325°C) or supercritical (374°C) reservoir. This has severely hindered engineered reservoir creation, management and utilization, as hot zones and cool water intrusions cannot be understood over time. The lack of a insulated electrical wire and fibermore » cable solution is a fundamental limitation to the viability of this energy source. The High Temperature Downhole Tools target specification is development of tools and sensors for logging and monitoring wellbore conditions at depths of up to 10,000 meters and temperatures up to 374oC. It well recognized in the industry that no current electronic or fiber cable can be successfully deployed in a well and function successfully for more a few days at temperatures over 240oC. The goal of this project was to raise this performance level significantly. Prysmian Group’s objective in this project was to develop a complete, multi-purpose cable solution for long-term deployment in geothermal wells/reservoirs that can be used with the widest variety of sensors. In particular, the overall project objective was to produce a manufacturable cable design that can perform without serious degradation: • At temperatures up to 374°C; • At pressures up to 220 bar; • In a hydrogen-rich environment; and • For the life of the well (> 5 years). This cable incorporates: • Specialty optical fibers, with specific glass chemistry and high temperature and pressure protective coatings for data communication and distributed temperature and pressure sensing, and • High-temperature insulated wire conductors Prysmian Group has developed a geothermal fiber optic cable (GFOC) solution which incorporates novel glass chemistry for optical fibers to operate at the required bandwidths in high temperature/high pressure hydrogen rich environments with fiber protection, high temperature insulated conductors and protective cladding for cable components. The cable solution has been tested in a geothermal installation for 10 months. The electrical insulation and optical fibers have been validated through laboratory testing to ensure successful operation for greater than 5 years at 300°C, with the possibility of higher temperatures depending on the particular well environment. With the 300°C optical fiber and electrical insulation developments completed and validated in laboratory tests the greatest challenge to a complete 300°C cable solution was protecting the optical fibers in the cable. Optical fibers are typically incased in a protective tube where the tube is filled with a gel. The gel serves as mechanical protection, prevent moisture ingress, and can include hydrogen scavenging materials. A suitable gel for use at 300°C could not be identified and an industrialized alternative was not fully attained. Despite the problems encountered and the lower long-term operating temperature of the cable solution, the project showed success in developing a complete cable solution for a large portion of the geothermal wells in operation today. Further work to obtain the higher long-term temperature goal of the project can be achieved based on the knowledge gained in the current project. This project is significant for many reasons including the new materials science, manufacturing technology, energy independence, and jobs created and will create.« less

Derived and thiourea-functionalized silica for cadmium removal: isotherm, kinetic and thermodynamic studies

NASA Astrophysics Data System (ADS)

Omotunde, Iyanu; Okoronkwo, Afamefuna; Oluwashina, Olugbenga

2018-03-01

The present study explored the feasibility of using derived and thiourea-functionalized silica as adsorbent for the removal of cadmium under different experimental conditions. Effects of various parameters such as function of point of zero charge (pHPZC), solution pH, sorbent-sorbate resident time and ratio, concentration and temperature were investigated. The sorption of cadmium followed the pseudo-second-order rate kinetics. Thermodynamic studies revealed that the sorption of cadmium was endothermic and spontaneous, with good affinity toward the sorbent. Various isotherm models, viz. Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Harkins-Jura, and Halsey isotherms were used to analyze the equilibrium data at different temperatures. The Freundlich, Halsey, Langmuir, and Temkin models were found to be in good agreement with the experimental data with high R 2, low RMSE, and low χ 2 values. The results show that the sorption capacity increases with an increase in solution temperature from 28 to 65 °C. The maximum sorption capacity calculated from Langmuir isotherm was 27.55 and 28.41 mg g-1 for derived and thiourea-functionalized silica, respectively, at optimum condition of pH 5 and contact time of 120 min.

Studies on the effect of acid treated TiO{sub 2} on the electrical and tensile properties of hexanoyl chitosan-polystyrene-LiCF{sub 3}SO{sub 3} composite polymer electrolytes

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

Hanif, Nur Shazlinda Muhammad; Shahril, Nur Syuhada Mohd; Azmar, Amisha

2015-08-28

Composite polymer electrolytes (CPEs) comprised of hexanoyl chitosan:polystyrene (90:10) blend, lithium triflouromethanesulfonate (LiCF{sub 3}SO{sub 3}) salt and titanium oxide (TiO{sub 2}) filler were prepared by solution casting technique. The TiO{sub 2} fillers were treated with 2% sulphuric acid (H{sub 2}SO{sub 4}) aqueous solution. The effect of acid treated TiO{sub 2} on the electrical and tensile properties of the electrolytes were investigated. Acid treated TiO{sub 2} decreased the electrolyte conductivity. Both the dielectric constant and dielectric loss decrease with increasing frequency and increases with increasing temperature. Relaxation times for ionic carriers were extracted from the loss tangent maximum peak at variousmore » temperatures. A distribution of relaxation time implied the non-Debye response. At all frequencies, ac conductivity increases with increasing temperature. An enhancement in the Young’s modulus was observed with the addition of TiO{sub 2}. The Young’s modulus increases with increasing TiO{sub 2} content. This is discussed using the percolation concept.« less

Search for extraterrestrial life using chiral molecules: mandelate racemase as a test case.

PubMed

Thaler, Tracey L; Gibbs, Phillip R; Trebino, Rick P; Bommarius, Andreas S

2006-12-01

We have investigated an enzymatic racemization reaction as a marker for extraterrestrial life, which resulted in a change in optical rotation of a mandelic acid over time, as measured by polarimetry. Mandelate racemase was active in aqueous buffer in a temperature range between 0 degrees C and 70 degrees C and also in concentrated ammonium salt solutions and water-in-oil microemulsions in a temperature range between -30 degrees C and 60-70 degrees C; however, the enzyme was not active in several organic cryosolvents. Thus, we have demonstrated that concentrated ammonium salt solutions and water-in-oil microemulsions, both of which are able to form on extraterrestrial planets and moons in the presence of liquid water, are suitable media for enzyme reactions at subzero temperatures. Kinetic data for the mandelate racemase reaction obtained by polarimetry, while reproducible and internally consistent, differed significantly from several sets of data obtained previously by other methods such as chromatography and hydrogen-deuterium exchange. However, we conclude that reactions yielding a polarimetric signal, such as the racemizations employed in this work, are suitable mechanisms by which to utilize a change in chirality over time as a tool to detect signs of life.

Using diurnal temperature signals to infer vertical groundwater-surface water exchange

USGS Publications Warehouse

Irvine, Dylan J.; Briggs, Martin A.; Lautz, Laura K.; Gordon, Ryan P.; McKenzie, Jeffrey M.; Cartwright, Ian

2017-01-01

Heat is a powerful tracer to quantify fluid exchange between surface water and groundwater. Temperature time series can be used to estimate pore water fluid flux, and techniques can be employed to extend these estimates to produce detailed plan-view flux maps. Key advantages of heat tracing include cost-effective sensors and ease of data collection and interpretation, without the need for expensive and time-consuming laboratory analyses or induced tracers. While the collection of temperature data in saturated sediments is relatively straightforward, several factors influence the reliability of flux estimates that are based on time series analysis (diurnal signals) of recorded temperatures. Sensor resolution and deployment are particularly important in obtaining robust flux estimates in upwelling conditions. Also, processing temperature time series data involves a sequence of complex steps, including filtering temperature signals, selection of appropriate thermal parameters, and selection of the optimal analytical solution for modeling. This review provides a synthesis of heat tracing using diurnal temperature oscillations, including details on optimal sensor selection and deployment, data processing, model parameterization, and an overview of computing tools available. Recent advances in diurnal temperature methods also provide the opportunity to determine local saturated thermal diffusivity, which can improve the accuracy of fluid flux modeling and sensor spacing, which is related to streambed scour and deposition. These parameters can also be used to determine the reliability of flux estimates from the use of heat as a tracer.

Study on temperature sensitivity of topological insulators based on long-period fiber grating

NASA Astrophysics Data System (ADS)

Luo, Jianhua; Zhao, Chenghai; Li, Jianbo; He, Mengdong

2017-06-01

Based on a long-period fiber grating, we conducted experimental research on the temperature sensitivity of topological insulators. The long-period fiber grating and topological insulators solution were encapsulated in a capillary tube using UV glue, and the temperature response was measured. Within a range of 35 to 75 centigrade, one resonance dip of a long-period fiber grating exhibits a redshift of 1.536 nm. The temperature sensitivity is about 7.7 times of an ordinary long-period fiber grating's sensitivity (0.005 nm/°C). A numerical simulation is also performed on the basis of the experiments.

Halogen effect for improving high temperature oxidation resistance of Ti-50Al by anodization

NASA Astrophysics Data System (ADS)

Mo, Min-Hua; Wu, Lian-Kui; Cao, Hua-Zhen; Lin, Jun-Pin; Zheng, Guo-Qu

2017-06-01

The high temperature oxidation resistance of Ti-50Al was significantly improved via halogen effect which was achieved by anodizing in an ethylene glycol solution containing with fluorine ion. The anodized Ti-50Al with holes and micro-cracks could be self-repaired during oxidation at 1000 °C. The thickness of the oxide scale increases with the prolonging of oxidation time. On the basis of halogen effect for improving the high temperature oxidation resistance of Ti-50Al by anodization, only fluorine addition into the electrolyte can effectively improve the high temperature oxidation resistance of Ti-50Al.

Influence of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) on zinc electrodeposition

NASA Astrophysics Data System (ADS)

Lehr, I. L.; Saidman, S. B.

2012-03-01

This work is a study of the electrodeposition of zinc onto SAE 4140 steel electrodes using solutions containing zinc sulfate and bis(2-ethylhexyl) sodium sulfosuccinate (AOT). The influence of different parameters such as electrolyte concentration, electrodeposition time and temperature on the morphology of the electrodeposits was analyzed. The deposits were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffraction. The variation of open circuit potential over time in chloride solutions was also evaluated. The nucleation-growth process and consequently the morphology of the electrodeposits are modified in the presence of AOT. The surfactant induces the formation of a porous deposit.

Detailed transient heme structures of Mb-CO in solution after CO dissociation: an X-ray transient absorption spectroscopic study.

PubMed

Stickrath, Andrew B; Mara, Michael W; Lockard, Jenny V; Harpham, Michael R; Huang, Jier; Zhang, Xiaoyi; Attenkofer, Klaus; Chen, Lin X

2013-04-25

Although understanding the structural dynamics associated with ligand photodissociation is necessary in order to correlate structure and function in biological systems, few techniques are capable of measuring the ultrafast dynamics of these systems in solution-phase at room temperature. We present here a detailed X-ray transient absorption (XTA) study of the photodissociation of CO-bound myoglobin (Fe(II)CO-Mb) in room-temperature aqueous buffer solution with a time resolution of 80 ps, along with a general procedure for handling biological samples under the harsh experimental conditions that transient X-ray experiments entail. The XTA spectra of (Fe(II)CO-Mb) exhibit significant XANES and XAFS alterations following 527 nm excitation, which remain unchanged for >47 μs. These spectral changes indicate loss of the CO ligand, resulting in a five-coordinate, domed heme, and significant energetic reorganization of the 3d orbitals of the Fe center. With the current experimental setup, each X-ray pulse in the pulse train, separated by ~153 ns, can be separately discriminated, yielding snapshots of the myoglobin evolution over time. These methods can be easily applied to other biological systems, allowing for simultaneous structural and electronic measurements of any biological system with both ultrafast and slow time resolutions, effectively mapping out all of the samples' relevant physiological processes.

Optimization of thiamethoxam adsorption parameters using multi-walled carbon nanotubes by means of fractional factorial design.

PubMed

Panić, Sanja; Rakić, Dušan; Guzsvány, Valéria; Kiss, Erne; Boskovic, Goran; Kónya, Zoltán; Kukovecz, Ákos

2015-12-01

The aim of this work was to evaluate significant factors affecting the thiamethoxam adsorption efficiency using oxidized multi-walled carbon nanotubes (MWCNTs) as adsorbents. Five factors (initial solution concentration of thiamethoxam in water, temperature, solution pH, MWCNTs weight and contact time) were investigated using 2V(5-1) fractional factorial design. The obtained linear model was statistically tested using analysis of variance (ANOVA) and the analysis of residuals was used to investigate the model validity. It was observed that the factors and their second-order interactions affecting the thiamethoxam removal can be divided into three groups: very important, moderately important and insignificant ones. The initial solution concentration was found to be the most influencing parameter on thiamethoxam adsorption from water. Optimization of the factors levels was carried out by minimizing those parameters which are usually critical in real life: the temperature (energy), contact time (money) and weight of MWCNTs (potential health hazard), in order to maximize the adsorbed amount of the pollutant. The results of maximal adsorbed thiamethoxam amount in both real and optimized experiments indicate that among minimized parameters the adsorption time is one that makes the largest difference. The results of this study indicate that fractional factorial design is very useful tool for screening the higher number of parameters and reducing the number of adsorption experiments. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of in ovo injection of carbohydrates on embryonic metabolism, hatchability, and subsequent somatic characteristics of broiler hatchlings.

PubMed

Zhai, W; Gerard, P D; Pulikanti, R; Peebles, E D

2011-10-01

The effects of the in ovo injection of different carbohydrate solutions on the internal egg temperature (IT), hatchability, and time of hatch of embryonated Ross × Ross 708 broiler hatching eggs were determined. In addition, the BW, liver weight, yolk sac weight (YSW), and yolk-free BW (YFBW) of the embryos on d 19.5 of incubation and of the chicks on day of hatch were determined. Eggs containing live embryos were injected in the amnion on d 18.5 of incubation using an automated multiple-egg injector. Solution injections delivered 1.2 mL of physiological saline (0.85%) alone or with a supplemental carbohydrate. The following supplemental carbohydrates were separately dissolved in saline at a concentration of 0.3 g/mL: glucose, fructose, sucrose, maltose, and dextrin. Temperature transponders were implanted in the air cells of embryonated and nonembryonated eggs after in ovo injection for the detection of IT at 6, 14, and 22 h after injection. The IT of embryonated eggs was significantly greater than that of nonembryonated eggs at all 3 times after the treatment period. Eggs that were injected with saline with or without supplemental carbohydrates experienced a reduction in IT when compared with control eggs whose shells were perforated without solution delivery, and the decrease in IT was associated with a delay in hatch time. Liver weight was negatively related to YSW and positively related to YFBW, and YSW was negatively related to YFBW. Although the saline and carbohydrate solution injections increased chick BW compared with noninjected controls, chick YFBW was decreased in the maltose- and sucrose-injected groups. In conclusion, the injection of 1.2 mL of saline with or without supplemental carbohydrates lowered embryonic metabolism, as reflected by a lower IT and a delay in time of hatch. However, effects of the different carbohydrate solutions on yolk absorption and tissue deposition in yolk-free embryos varied. These results suggest that lower volumes for solutions containing maltose, sucrose, or fructose should be considered for in ovo injection.

Complexing Agents and pH Influence on Chemical Durability of Type I Molded Glass Containers.

PubMed

Biavati, Alberto; Poncini, Michele; Ferrarini, Arianna; Favaro, Nicola; Scarpa, Martina; Vallotto, Marta

2017-01-01

Among the factors that affect the glass surface chemical durability, pH and complexing agents present in aqueous solution have the main role. Glass surface attack can be also related to the delamination issue causing glass particles' appearance in the pharmaceutical preparation. A few methods to check for glass containers delamination propensity and some control guidelines have been proposed. The present study emphasizes the possible synergy between a few complexing agents with pH on borosilicate glass chemical durability.Hydrolytic attack was performed in small-volume 23 mL type I glass containers autoclaved according to the European Pharmacopoeia or United States Pharmacopeia for 1 h at 121 °C, in order to enhance the chemical attack due to time, temperature, and the unfavorable surface/volume ratio. Solutions of 0.048 M or 0.024 M (M/L) of the acids citric, glutaric, acetic, EDTA (ethylenediaminetetraacetic acid), together with sodium phosphate with water for comparison, were used for the trials. The pH was adjusted ±0.05 units at fixed values 5.5, 6.6, 7, 7.4, 8, and 9 by LiOH diluted solution.Because silicon is the main glass network former, silicon release into the attack solutions was chosen as the main index of the glass surface attack and analysed by inductively coupled plasma atomic emission spectrophotometry. The work was completed by the analysis of the silicon release in the worst attack conditions of molded glass, soda lime type II glass, and tubing borosilicate glass vials to compare different glass compositions and forming technologies. Surface analysis by scanning electron microscopy was finally performed to check for the surface status after the worst chemical attack condition by citric acid. LAY ABSTRACT: Glass, like every packaging material, can have some usage limits, mainly in basic pH solutions. The issue of glass surface degradation particles that appear in vials (delamination) has forced a number of drug product recalls in recent years. To prevent such situations, pharmaceutical and biopharmaceutical manufacturers need to understand the reasons for accelerate surface glass corrosion mainly in the case of injectables.Some drugs can contain active components with known ability to corrode glass silica networks. Sometimes these ingredients are dissolved in an alkaline medium that dramatically increases the glass corrosion and potentially causes the issue. As this action is strongly affected by time and temperature, flaking may become visible only after a long storage time. The purpose of this investigation is to verify the borosilicate glass chemical durability during controlled conditions of time and temperature when in contact with testing solutions containing different complexing agents by varying the pH. Si concentration in the extract solution is taken as an index of glass dissolution during constant autoclaving conditions for 1 h at 121 °C, which simulates approximately five years of contact at room temperature.Acetate, citrate, ethylenediaminetetraacetic acid (EDTA), phosphate, and glutarate 0.048 M or 0.024 M solutions were used at increasing pH from 5.5 to 9.0. The chemical durability of two borosilicate tubing glass vials of different glass compositions were compared with the molded one in the worst attack conditions by citric acid. Even if no delamination issue has been experienced by this study in type I molded and tubing containers, the conclusions developed can provide pharmaceutical manufacturers with useful information to prevent glass delamination risk in their processes. © PDA, Inc. 2017.

Temperature Oscillation Modulated Self-Assembly of Periodic Concentric Layered Magnesium Carbonate Microparticles

PubMed Central

Li, Shihong; Wang, Zheng Jim; Chang, Ting-Tung

2014-01-01

Intriguing patterns of periodic, concentric, layered, mineral microstructure are present in nature and organisms, yet they have elusive geneses. We hypothesize temperature oscillation can be an independent factor that causes the self-assembly of such patterns in mineral phases synthesized in solution. Static experiments verify that rhythmic concentric multi-layered magnesium carbonate microhemispheres can be synthesized from bicarbonate solution by temperature oscillation, without use of a chemical template, additive or gel-diffusion system. Appropriate reactant concentration and initial pH value can restrain the competitive growth of other mineral generations. Polarized light microscopy images indicate the microhemispheres are crystalline and the crystallinity increases with incubation time. The thickness of a single mineral layer of microhemisphere in microscale is precisely controlled by the waveform parameters of the temperature oscillation, while the layer number, which can reach tens to about one hundred, is constrained by the temperature oscillation period number. FT-IR spectra show that these microhemispheres synthesized under different conditions can be identified as the basic form of magnesium carbonate, hydromagnesite (Mg5(CO3)4(OH)2⋅4H2O). SEM images exhibit the characteristic microscopic texture of the alternating dark and light rings of these microhemispheres. TEM images and ED patterns suggest the nanoflakes of microhemispheres are present in polycrystalline form with some degree of oriented assembly. The temperature oscillation modulated self-assembly may offer a new mechanism to understand the formation of layered microstructure of minerals in solution, and provide a non-invasive and programmable means to synthesize hierarchically ordered materials. PMID:24520410

Removal of Hexavalent Chromium by Adsorption on Microwave Assisted Activated Carbon Prepared from Stems of Leucas Aspera

NASA Astrophysics Data System (ADS)

Shanmugalingam, A.; Murugesan, A.

2018-05-01

This study reports adsorption of Cr(VI) ions from aqueous solution using activated carbon that was prepared from stems of Leucas aspera. Eight hundred and fifty watts power of microwave radiation, 12 min of radiation time, 60% of ZnCl2 solution and 24 h of impregnation time are the optimal parameters to prepare efficient carbon effective activated carbon. It was designated as MWLAC (Microwave assisted Zinc chloride activated Leucas aspera carbon). Various adsorption characteristics such as dose of the adsorbent, agitation time, initial Cr(VI) ion concentration, pH of the solution and temperature on adsorption were studied for removal of Cr(VI) ions from aqueous solution by batch mode. Also the equilibrium adsorption was analyzed by the Langmuir, Freundlich, Tempkin and D-R isotherm models. The order of best describing isotherms was given based on R2 value. The pseudo-second-order kinetic model best fitted with the Cr(VI) adsorption data. Thermodynamic parameters were also determined and results suggest that the adsorption process is a spontaneous, endothermic and proceeded with increased randomness.

Removal of Copper(II) Ions in Aqueous Solutions Using Tannin-Rich Plants as Natural Bio-Adsorbents

NASA Astrophysics Data System (ADS)

Paksamut, J.; Boonsong, P.

2018-03-01

In this study, the purpose of our interest is to investigatethe adsorption behavior of copper (II) ions in aqueous solution using some tannin-rich plants as natural bio-adsorbents such as mangosteen peels (Garciniamangostana L.), cassava leaves (Manihotesculenta Crantz) and Thai copper pod leaves (Sennasiamea (Lam.)) as powder form in different dosage of adsorbent plant materials.The adsorption capacities at different pH of solution and contact time were performed.All the experiments in this studywere chosen at room temperature by batch technique. From the experimental results showed that cassava leaves gave better adsorbent properties than mangosteen peels and Thai copper pod leaves. The increasing dosage of all adsorbents and contact time have been found to increase adsorption capacities. In this respect, the adsorption capacities depend crucially on the adsorbents and contact time. The optimum pH of copper (II) ions adsorption was pH4. According to this work, it was observed that bioadsorbent materials from tannin-rich plants could be used to remove copper (II) ions from aqueous solutions.

Dynamic microscale temperature gradient in a gold nanorod solution measured by diffraction-limited nanothermometry

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

Li, Chengmingyue; Gan, Xiaosong; Li, Xiangping

2015-09-21

We quantify the dynamic microscale temperature gradient in a gold nanorod solution using quantum-dot-based microscopic fluorescence nanothermometry. By incorporating CdSe quantum dots into the solution as a nanothermometer, precise temperature mapping with diffraction-limited spatial resolution and sub-degree temperature resolution is achieved. The acquired data on heat generation and dissipation show an excellent agreement with theoretical simulations. This work reveals an effective approach for noninvasive temperature regulation with localized nanoheaters in microfluidic environment.

Predicting chemical degradation during storage from two successive concentration ratios: Theoretical investigation.

PubMed

Peleg, Micha; Normand, Mark D

2015-09-01

When a vitamin's, pigment's or other food component's chemical degradation follows a known fixed order kinetics, and its rate constant's temperature-dependence follows a two parameter model, then, at least theoretically, it is possible to extract these two parameters from two successive experimental concentration ratios determined during the food's non-isothermal storage. This requires numerical solution of two simultaneous equations, themselves the numerical solutions of two differential rate equations, with a program especially developed for the purpose. Once calculated, these parameters can be used to reconstruct the entire degradation curve for the particular temperature history and predict the degradation curves for other temperature histories. The concept and computation method were tested with simulated degradation under rising and/or falling oscillating temperature conditions, employing the exponential model to characterize the rate constant's temperature-dependence. In computer simulations, the method's predictions were robust against minor errors in the two concentration ratios. The program to do the calculations was posted as freeware on the Internet. The temperature profile can be entered as an algebraic expression that can include 'If' statements, or as an imported digitized time-temperature data file, to be converted into an Interpolating Function by the program. The numerical solution of the two simultaneous equations requires close initial guesses of the exponential model's parameters. Programs were devised to obtain these initial values by matching the two experimental concentration ratios with a generated degradation curve whose parameters can be varied manually with sliders on the screen. These programs too were made available as freeware on the Internet and were tested with published data on vitamin A. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fast response of sprayed vanadium pentoxide (V2O5) nanorods towards nitrogen dioxide (NO2) gas detection

NASA Astrophysics Data System (ADS)

Mane, A. A.; Suryawanshi, M. P.; Kim, J. H.; Moholkar, A. V.

2017-05-01

The V2O5 nanorods have been successfully spray deposited at optimized substrate temperature of 400 °C onto the glass substrates using vanadium trichloride (VCl3) solution of different concentrations. The effect of solution concentration on the physicochemical and NO2 gas sensing properties of sprayed V2O5 nanorods is studied at different operating temperatures and gas concentrations. The XRD study reveals the formation of V2O5 having an orthorhombic symmetry. The FE-SEM micrographs show the nanorods-like morphology of V2O5. The AFM micrographs exhibit a well covered granular surface topography. For direct allowed transition, the band gap energy values are found to be decreased from 2.45 eV to 2.42 eV. The nanorods deposited with 30 mM solution concentration shows the maximum response of 24.2% for 100 ppm NO2 gas concentration at an operating temperature of 200 °C with response and recovery times of 13 s and 140 s, respectively. Finally, the chemisorption mechanism of NO2 gas on the V2O5 nanorods is discussed.

Finite Element Solution of Unsteady Mixed Convection Flow of Micropolar Fluid over a Porous Shrinking Sheet

PubMed Central

Gupta, Diksha; Singh, Bani

2014-01-01

The objective of this investigation is to analyze the effect of unsteadiness on the mixed convection boundary layer flow of micropolar fluid over a permeable shrinking sheet in the presence of viscous dissipation. At the sheet a variable distribution of suction is assumed. The unsteadiness in the flow and temperature fields is caused by the time dependence of the shrinking velocity and surface temperature. With the aid of similarity transformations, the governing partial differential equations are transformed into a set of nonlinear ordinary differential equations, which are solved numerically, using variational finite element method. The influence of important physical parameters, namely, suction parameter, unsteadiness parameter, buoyancy parameter and Eckert number on the velocity, microrotation, and temperature functions is investigated and analyzed with the help of their graphical representations. Additionally skin friction and the rate of heat transfer have also been computed. Under special conditions, an exact solution for the flow velocity is compared with the numerical results obtained by finite element method. An excellent agreement is observed for the two sets of solutions. Furthermore, to verify the convergence of numerical results, calculations are conducted with increasing number of elements. PMID:24672310

Steady Secondary Flows Generated by Periodic Compression and Expansion of an Ideal Gas in a Pulse Tube

NASA Technical Reports Server (NTRS)

Lee, Jeffrey M.

1999-01-01

This study establishes a consistent set of differential equations for use in describing the steady secondary flows generated by periodic compression and expansion of an ideal gas in pulse tubes. Also considered is heat transfer between the gas and the tube wall of finite thickness. A small-amplitude series expansion solution in the inverse Strouhal number is proposed for the two-dimensional axisymmetric mass, momentum and energy equations. The anelastic approach applies when shock and acoustic energies are small compared with the energy needed to compress and expand the gas. An analytic solution to the ordered series is obtained in the strong temperature limit where the zeroth-order temperature is constant. The solution shows steady velocities increase linearly for small Valensi number and can be of order I for large Valensi number. A conversion of steady work flow to heat flow occurs whenever temperature, velocity or phase angle gradients are present. Steady enthalpy flow is reduced by heat transfer and is scaled by the Prandtl times Valensi numbers. Particle velocities from a smoke-wire experiment were compared with predictions for the basic and orifice pulse tube configurations. The theory accurately predicted the observed steady streaming.

Hydrophilic Association in a Dilute Glutamine Solution Persists Independent of Increasing Temperature.

PubMed

Rhys, Natasha H; Soper, Alan K; Dougan, Lorna

2015-12-24

Recent studies suggest that hydrophilic interactions play an important role in controlling self-assembly in biological processes. To explore the effect of temperature on this interaction, we extend our previous work on the glutamine-water system at 24 °C (at a mole ratio of 1 glutamine to 269 water molecules) and present additional neutron diffraction data, at the same concentration, at 37 and 60 °C, using hydrogen/deuterium substitution on the water and glutamine, coupled with further extensive empirical potential structure refinement computer simulations. Taking all the possible hydrophilic couplings between glutamine molecules into account, we find that nearly one-fifth of the glutamines in solution are linked by hydrogen bonds at any one time. This number contrasts strongly with the ∼3-4% fraction found in the same simulation with random packing and no hydrogen bonds. Within the uncertainties imposed by dilute solution statistics, we find no temperature dependence in these values. The clusters are highly transitory, forming and disappearing rapidly as the simulations proceed. Hydrophobic association of the alkyl groups on glutamine without concomitant hydrophilic association of the charged head and side-chain groups is only weakly observed.

Effect of Silk Protein Processing on Drug Delivery from Silk Films

PubMed Central

Pritchard, Eleanor M.; Hu, Xiao; Finley, Violet; Kuo, Catherine K.; Kaplan, David L.

2013-01-01

Sericin removal from the core fibroin protein of silkworm silk is a critical first step in the use of silk for biomaterial-related applications, but degumming can affect silk biomaterial properties, including molecular weight, viscosity, diffusivity and degradation behavior. Increasing the degumming time (10, 30, 60 and 90 min) decreases the average molecular weight of silk protein in solution, silk solution viscosity, and silk film glass transition temperature, and increases the rate of degradation of silk film by protease. Model compounds spanning a range of physical-chemical properties generally showed an inverse relationship between degumming time and release rate through a varied degumming time silk coating. Degumming provides a useful control point to manipulate silk’s material properties. PMID:23349062

Modeling of porosity loss during compaction and cementation of sandstones

NASA Astrophysics Data System (ADS)

Lemée, Claire; Guéguen, Yves

1996-10-01

Irreversible inelastic processes are responsible for mechanical and chemical compaction of sedimentary rocks at the time of burying. Our purpose is to describe the inelastic response of the rock at large time scales. In order to do this, we build a model that describes how porosity progressively decreases at depth. We use a previous geometrical model for the compaction process of a sandstone by grain interpenetration that is restricted to the case of mass conservation. In addition, we introduce a compaction equilibrium concept. Solid grains can support stresses up to a critical effective stress, σc, before plastic flow occurs. This critical stress depends on temperature and is derived from the pressure-solution deformation law. Pressure solution is the plastic deformation mechanism implemented during compaction. Our model predicts a porosity destruction at a depth of about 3 km. This model has the property to define a range of compaction curves. We investigate the sensitivity of the model to the main input parameters: liquid film thickness, grain size, temperature gradient, and activation energy.

Thermal stability, storage and release of proteins with tailored fit in silica

NASA Astrophysics Data System (ADS)

Chen, Yun-Chu; Smith, Tristan; Hicks, Robert H.; Doekhie, Aswin; Koumanov, Francoise; Wells, Stephen A.; Edler, Karen J.; van den Elsen, Jean; Holman, Geoffrey D.; Marchbank, Kevin J.; Sartbaeva, Asel

2017-04-01

Biological substances based on proteins, including vaccines, antibodies, and enzymes, typically degrade at room temperature over time due to denaturation, as proteins unfold with loss of secondary and tertiary structure. Their storage and distribution therefore relies on a “cold chain” of continuous refrigeration; this is costly and not always effective, as any break in the chain leads to rapid loss of effectiveness and potency. Efforts have been made to make vaccines thermally stable using treatments including freeze-drying (lyophilisation), biomineralisation, and encapsulation in sugar glass and organic polymers. Here for the first time we show that proteins can be enclosed in a deposited silica “cage”, rendering them stable against denaturing thermal treatment and long-term ambient-temperature storage, and subsequently released into solution with their structure and function intact. This “ensilication” method produces a storable solid protein-loaded material without the need for desiccation or freeze-drying. Ensilication offers the prospect of a solution to the “cold chain” problem for biological materials, in particular for vaccines.

Thermal stability, storage and release of proteins with tailored fit in silica.

PubMed

Chen, Yun-Chu; Smith, Tristan; Hicks, Robert H; Doekhie, Aswin; Koumanov, Francoise; Wells, Stephen A; Edler, Karen J; van den Elsen, Jean; Holman, Geoffrey D; Marchbank, Kevin J; Sartbaeva, Asel

2017-04-24

Biological substances based on proteins, including vaccines, antibodies, and enzymes, typically degrade at room temperature over time due to denaturation, as proteins unfold with loss of secondary and tertiary structure. Their storage and distribution therefore relies on a "cold chain" of continuous refrigeration; this is costly and not always effective, as any break in the chain leads to rapid loss of effectiveness and potency. Efforts have been made to make vaccines thermally stable using treatments including freeze-drying (lyophilisation), biomineralisation, and encapsulation in sugar glass and organic polymers. Here for the first time we show that proteins can be enclosed in a deposited silica "cage", rendering them stable against denaturing thermal treatment and long-term ambient-temperature storage, and subsequently released into solution with their structure and function intact. This "ensilication" method produces a storable solid protein-loaded material without the need for desiccation or freeze-drying. Ensilication offers the prospect of a solution to the "cold chain" problem for biological materials, in particular for vaccines.

Density relaxation and particle motion characteristics in a non-ionic deep eutectic solvent (acetamide + urea): time-resolved fluorescence measurements and all-atom molecular dynamics simulations.

PubMed

Das, Anuradha; Das, Suman; Biswas, Ranjit

2015-01-21

Temperature dependent relaxation dynamics, particle motion characteristics, and heterogeneity aspects of deep eutectic solvents (DESs) made of acetamide (CH3CONH2) and urea (NH2CONH2) have been investigated by employing time-resolved fluorescence measurements and all-atom molecular dynamics simulations. Three different compositions (f) for the mixture [fCH3CONH2 + (1 - f)NH2CONH2] have been studied in a temperature range of 328-353 K which is ∼120-145 K above the measured glass transition temperatures (∼207 K) of these DESs but much lower than the individual melting temperature of either of the constituents. Steady state fluorescence emission measurements using probe solutes with sharply different lifetimes do not indicate any dependence on excitation wavelength in these metastable molten systems. Time-resolved fluorescence anisotropy measurements reveal near-hydrodynamic coupling between medium viscosity and rotation of a dissolved dipolar solute. Stokes shift dynamics have been found to be too fast to be detected by the time-resolution (∼70 ps) employed, suggesting extremely rapid medium polarization relaxation. All-atom simulations reveal Gaussian distribution for particle displacements and van Hove correlations, and significant overlap between non-Gaussian (α2) and new non-Gaussian (γ) heterogeneity parameters. In addition, no stretched exponential relaxations have been detected in the simulated wavenumber dependent acetamide dynamic structure factors. All these results are in sharp contrast to earlier observations for ionic deep eutectics with acetamide [Guchhait et al., J. Chem. Phys. 140, 104514 (2014)] and suggest a fundamental difference in interaction and dynamics between ionic and non-ionic deep eutectic solvent systems.

Density relaxation and particle motion characteristics in a non-ionic deep eutectic solvent (acetamide + urea): Time-resolved fluorescence measurements and all-atom molecular dynamics simulations

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

Das, Anuradha; Das, Suman; Biswas, Ranjit, E-mail: ranjit@bose.res.in

2015-01-21

Temperature dependent relaxation dynamics, particle motion characteristics, and heterogeneity aspects of deep eutectic solvents (DESs) made of acetamide (CH{sub 3}CONH{sub 2}) and urea (NH{sub 2}CONH{sub 2}) have been investigated by employing time-resolved fluorescence measurements and all-atom molecular dynamics simulations. Three different compositions (f) for the mixture [fCH{sub 3}CONH{sub 2} + (1 − f)NH{sub 2}CONH{sub 2}] have been studied in a temperature range of 328-353 K which is ∼120-145 K above the measured glass transition temperatures (∼207 K) of these DESs but much lower than the individual melting temperature of either of the constituents. Steady state fluorescence emission measurements using probemore » solutes with sharply different lifetimes do not indicate any dependence on excitation wavelength in these metastable molten systems. Time-resolved fluorescence anisotropy measurements reveal near-hydrodynamic coupling between medium viscosity and rotation of a dissolved dipolar solute. Stokes shift dynamics have been found to be too fast to be detected by the time-resolution (∼70 ps) employed, suggesting extremely rapid medium polarization relaxation. All-atom simulations reveal Gaussian distribution for particle displacements and van Hove correlations, and significant overlap between non-Gaussian (α{sub 2}) and new non-Gaussian (γ) heterogeneity parameters. In addition, no stretched exponential relaxations have been detected in the simulated wavenumber dependent acetamide dynamic structure factors. All these results are in sharp contrast to earlier observations for ionic deep eutectics with acetamide [Guchhait et al., J. Chem. Phys. 140, 104514 (2014)] and suggest a fundamental difference in interaction and dynamics between ionic and non-ionic deep eutectic solvent systems.« less

Density relaxation and particle motion characteristics in a non-ionic deep eutectic solvent (acetamide + urea): Time-resolved fluorescence measurements and all-atom molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Das, Anuradha; Das, Suman; Biswas, Ranjit

2015-01-01

Temperature dependent relaxation dynamics, particle motion characteristics, and heterogeneity aspects of deep eutectic solvents (DESs) made of acetamide (CH3CONH2) and urea (NH2CONH2) have been investigated by employing time-resolved fluorescence measurements and all-atom molecular dynamics simulations. Three different compositions (f) for the mixture [fCH3CONH2 + (1 - f)NH2CONH2] have been studied in a temperature range of 328-353 K which is ˜120-145 K above the measured glass transition temperatures (˜207 K) of these DESs but much lower than the individual melting temperature of either of the constituents. Steady state fluorescence emission measurements using probe solutes with sharply different lifetimes do not indicate any dependence on excitation wavelength in these metastable molten systems. Time-resolved fluorescence anisotropy measurements reveal near-hydrodynamic coupling between medium viscosity and rotation of a dissolved dipolar solute. Stokes shift dynamics have been found to be too fast to be detected by the time-resolution (˜70 ps) employed, suggesting extremely rapid medium polarization relaxation. All-atom simulations reveal Gaussian distribution for particle displacements and van Hove correlations, and significant overlap between non-Gaussian (α2) and new non-Gaussian (γ) heterogeneity parameters. In addition, no stretched exponential relaxations have been detected in the simulated wavenumber dependent acetamide dynamic structure factors. All these results are in sharp contrast to earlier observations for ionic deep eutectics with acetamide [Guchhait et al., J. Chem. Phys. 140, 104514 (2014)] and suggest a fundamental difference in interaction and dynamics between ionic and non-ionic deep eutectic solvent systems.

Thermal Analysis of Antenna Structures. Part 2: Panel Temperature Distribution

NASA Technical Reports Server (NTRS)

Schonfeld, D.; Lansing, F. L.

1983-01-01

This article is the second in a series that analyzes the temperature distribution in microwave antennas. An analytical solution in a series form is obtained for the temperature distribution in a flat plate analogous to an antenna surface panel under arbitrary temperature and boundary conditions. The solution includes the effects of radiation and air convection from the plate. Good agreement is obtained between the numerical and analytical solutions.

Nitric acid uptake by sulfuric acid solutions under stratospheric conditions - Determination of Henry's Law solubility

NASA Technical Reports Server (NTRS)

Reihs, Christa M.; Golden, David M.; Tolbert, Margaret A.

1990-01-01

The uptake of nitric acid by sulfuric acid solutions representative of stratospheric particulate at low temperatures was measured to determine the solubility of nitric acid in sulfuric acid solutions as a function of H2SO4 concentration and solution temperature. Solubilities are reported for sulfuric acid solutions ranging from 58 to 87 wt pct H2SO4 over a temperature range from 188 to 240 K, showing that, in general, the solubility of nitric acid increases with decreasing sulfuric acid concentration and with decreasing temperature. The measured solubilities indicate that nitric acid in the global stratosphere will be found predominantly in the gas phase.

Transient temperature distributions in simple conducting bodies steadily heated through a laminar boundary layer

NASA Technical Reports Server (NTRS)

Parker, Hermon M

1953-01-01

An analysis is made of the transient heat-conduction effects in three simple semi-infinite bodies: the flat insulated plate, the conical shell, and the slender solid cone. The bodies are assumed to have constant initial temperatures and, at zero time, to begin to move at a constant speed and zero angle of attack through a homogeneous atmosphere. The heat input is taken as that through a laminar boundary layer. Radiation heat transfer and transverse temperature gradients are assumed to be zero. The appropriate heat-conduction equations are solved by an iteration method, the zeroeth-order terms describing the situation in the limit of small time. The method is presented and the solutions are calculated to three orders which are sufficient to give reasonably accurate results when the forward edge has attained one-half the total temperature rise (nose half-rise time). Flight Mach number and air properties occur as parameters in the result. Approximate expressions for the extent of the conduction region and nose half-rise times as functions of the parameters of the problem are presented. (author)

A numerical tool for the calculation of non-equilibrium ionisation states in the solar corona and other astrophysical plasma environments

NASA Astrophysics Data System (ADS)

Bradshaw, S. J.

2009-07-01

Context: The effects of non-equilibrium processes on the ionisation state of strongly emitting elements in the solar corona can be extremely difficult to assess and yet they are critically important. For example, there is much interest in dynamic heating events localised in the solar corona because they are believed to be responsible for its high temperature and yet recent work has shown that the hottest (≥107 K) emission predicted to be associated with these events can be observationally elusive due to the difficulty of creating the highly ionised states from which the expected emission arises. This leads to the possibility of observing instruments missing such heating events entirely. Aims: The equations describing the evolution of the ionisaton state are a very stiff system of coupled, partial differential equations whose solution can be numerically challenging and time-consuming. Without access to specialised codes and significant computational resources it is extremely difficult to avoid the assumption of an equilibrium ionisation state even when it clearly cannot be justified. The aim of the current work is to develop a computational tool to allow straightforward calculation of the time-dependent ionisation state for a wide variety of physical circumstances. Methods: A numerical model comprising the system of time-dependent ionisation equations for a particular element and tabulated values of plasma temperature as a function of time is developed. The tabulated values can be the solutions of an analytical model, the output from a numerical code or a set of observational measurements. An efficient numerical method to solve the ionisation equations is implemented. Results: A suite of tests is designed and run to demonstrate that the code provides reliable and accurate solutions for a number of scenarios including equilibration of the ion population and rapid heating followed by thermal conductive cooling. It is found that the solver can evolve the ionisation state to recover exactly the equilibrium state found by an independent, steady-state solver for all temperatures, resolve the extremely small ionisation/recombination timescales associated with rapid temperature changes at high densities, and provide stable and accurate solutions for both dominant and minor ion population fractions. Rapid heating and cooling of low to moderate density plasma is characterised by significant non-equilibrium ionisation conditions. The effective ionisation temperatures are significantly lower than the electron temperature and the values found are in close agreement with the previous work of others. At the very highest densities included in the present study an assumption of equilibrium ionisation is found to be robust. Conclusions: The computational tool presented here provides a straightforward and reliable way to calculate ionisation states for a wide variety of physical circumstances. The numerical code gives results that are accurate and consistent with previous studies, has relatively undemanding computational requirements and is freely available from the author.

Acoustical experiment of yogurt fermentation process.

PubMed

Ogasawara, H; Mizutani, K; Ohbuchi, T; Nakamura, T

2006-12-22

One of the important factors through food manufacturing is hygienic management. Thus, food manufactures prove their hygienic activities by taking certifications like a Hazard Analysis and Critical Control Point (HACCP). This concept also applies to food monitoring. Acoustical measurements have advantage for other measurement in food monitoring because they make it possible to measure with noncontact and nondestructive. We tried to monitor lactic fermentation of yogurt by a probing sensor using a pair of acoustic transducers. Temperature of the solution changes by the reaction heat of fermentation. Consequently the sound velocity propagated through the solution also changes depending on the temperature. At the same time, the solution change its phase from liquid to gel. The transducers usage in the solution indicates the change of the temperature as the change of the phase difference between two transducers. The acoustic method has advantages of nondestructive measurement that reduces contamination of food product by measuring instrument. The sensor was inserted into milk with lactic acid bacterial stain of 19 degrees C and monitored phase retardation of propagated acoustic wave and its temperature with thermocouples in the mild. The monitoring result of fermentation from milk to Caspian Sea yogurt by the acoustic transducers with the frequency of 3.7 MHz started to show gradient change in temperature caused by reaction heat of fermentation but stop the gradient change at the end although the temperature still change. The gradient change stopped its change because of phase change from liquid to gel. The present method will be able to measure indirectly by setting transducers outside of the measuring object. This noncontact sensing method will have great advantage of reduces risk of food contamination from measuring instrument because the measurement probes are set out of fermentation reactor or food containers. Our proposed method will contribute to the hygienization for the food manufacture industry.

Effects of postharvest handling conditions on internalization and growth of Salmonella enterica in tomatoes.

PubMed

Zhou, Bin; Luo, Yaguang; Nou, Xiangwu; Yang, Yang; Wu, Yunpeng; Wang, Qin

2014-03-01

Salmonella internalization in tomatoes during postharvest handling is a major food safety concern. This study was conducted to determine the effect of immersion time, immersion depth, and temperature differential between bacterial suspension and tomato pulp on the internalization of Salmonella enterica in tomato fruits. The effect of storage temperature and duration on the survival and growth of internalized Salmonella cells was also evaluated. Overall, immersion time significantly affected the incidence and extent of S. enterica internalization (P < 0.0001), with a linear correlation between immersion time and Salmonella internalization. The depth of Salmonella internalization in tomato tissues also increased with increasing immersion time. Immersion time also significantly influenced the degree to which the temperature differential affected Salmonella internalization. With an immersion time of 2 min, the temperature differential had no significant effect on Salmonella internalization (P = 0.2536). However, with an immersion time of 15 min, a significantly larger Salmonella population became internalized in tomatoes immersed in solutions with a -30°F (-16.7°C) temperature differential. Internalized S. enterica cells persisted in the core tissues during 14 days of storage. Strain type and storage duration significantly affected (P < 0.05) both the frequency detected and the population of internalized Salmonella recovered, but storage temperatures of 55 to 70°F (12.8 to 21.1°C) did not (P > 0.05). These findings indicate the importance of preventing pathogen internalization during postharvest handling.

Effect of Microwave-Assisted Extraction on the Phenolic Compounds and Antioxidant Capacity of Blackthorn Flowers.

PubMed

Lovrić, Vanja; Putnik, Predrag; Kovačević, Danijela Bursać; Jukić, Marijana; Dragović-Uzelac, Verica

2017-06-01

This research was undertaken to investigate the influence of extraction parameters during microwave-assisted extraction on total phenolic content, total flavonoids, total hydroxycinnamic acids and total flavonols of blackthorn flowers as well as to evaluate the antioxidant capacity by two different methods (2,2-diphenyl-1-picrylhydrazyl free radical scavenging capacity and ferric reducing antioxidant power assays). The investigated extraction parameters were: solvent type and volume fraction of alcohol in solvent (50 and 70% aqueous solutions of ethanol and methanol), extraction time (5, 15 and 25 min) and extraction temperature (40, 50 and 60 °C) controlled by microwave power of 100, 200 and 300 W. Multivariate analysis of variance (MANOVA) was used to evaluate the differences at a 95% confidence level (p≤0.05). The obtained results show that aqueous solution of ethanol was more appropriate solvent for extraction of phenolic compounds (total flavonoids, total hydroxycinnamic acids and total flavonols) than aqueous solution of methanol. The amount of phenolic compounds was higher in 70% aqueous solution of ethanol or methanol, while higher antioxidant capacity was observed in 50% aqueous solution of methanol. Higher temperature of extraction improved the amount of phenolic compounds and also antioxidant capacity determined by 2,2-diphenyl-1-picrylhydrazyl free radical scavenging capacity assay. Extensive duration of extraction (15- to 25-minute interval) has a significant effect only on the increase of total phenolic content, while specific phenolic compound content and antioxidant capacity were the highest when microwave extraction time of 5 min was applied.

An exact solution for the solidification of a liquid slab of binary mixture

NASA Technical Reports Server (NTRS)

Antar, B. N.; Collins, F. G.; Aumalia, A. E.

1986-01-01

The time dependent temperature and concentration profiles of a one dimensional finite slab of a binary liquid alloy is investigated during solidification. The governing equations are reduced to a set of coupled, nonlinear initial value problems using the method outlined by Meyer. Two methods will be used to solve these equations. The first method uses a Runge-Kutta-Fehlberg integrator to solve the equations numerically. The second method comprises of finding closed form solutions of the equations.

Solution of non-continuum flows using BGK-type model with enforced relaxation of moments

NASA Astrophysics Data System (ADS)

Alekseenko, Alexander; Gimelshein, Sergey; Nguyen, Truong; Vedula, Prakash

2016-11-01

A BGK-type model with velocity dependent collision frequency and enforced relaxation rates for selected moments is applied to simulation of one- and two-dimensional super sonic flows. Relaxation rates of the moments are estimated by evaluating the full Boltzmann collision integral several times during the simulation. The solutions show improvements in velocity and temperature profiles as compared to the classical ES-BGK model. However, enforcement of relaxation rates for high order moments increases stiffness of the model.

Dynamic temperature fields under Mars landing sites and implications for supporting microbial life.

PubMed

Ulrich, Richard; Kral, Tim; Chevrier, Vincent; Pilgrim, Robert; Roe, Larry

2010-01-01

While average temperatures on Mars may be too low to support terrestrial life-forms or aqueous liquids, diurnal peak temperatures over most of the planet can be high enough to provide for both, down to a few centimeters beneath the surface for some fraction of the time. A thermal model was applied to the Viking 1, Viking 2, Pathfinder, Spirit, and Opportunity landing sites to demonstrate the dynamic temperature fields under the surface at these well-characterized locations. A benchmark temperature of 253 K was used as a lower limit for possible metabolic activity, which corresponds to the minimum found for specific terrestrial microorganisms. Aqueous solutions of salts known to exist on Mars can provide liquid solutions well below this temperature. Thermal modeling has shown that 253 K is reached beneath the surface at diurnal peak heating for at least some parts of the year at each of these landing sites. Within 40 degrees of the equator, 253 K beneath the surface should occur for at least some fraction of the year; and, within 20 degrees , it will be seen for most of the year. However, any life-form that requires this temperature to thrive must also endure daily excursions to far colder temperatures as well as periods of the year where 253 K is never reached at all.

Controls on soil solution nitrogen along an altitudinal gradient in the Scottish uplands.

PubMed

Jackson-Blake, L; Helliwell, R C; Britton, A J; Gibbs, S; Coull, M C; Dawson, L

2012-08-01

Nitrogen (N) deposition continues to threaten upland ecosystems, contributing to acidification, eutrophication and biodiversity loss. We present results from a monitoring study aimed at investigating the fate of this deposited N within a pristine catchment in the Cairngorm Mountains (Scotland). Six sites were established along an elevation gradient (486-908 m) spanning the key habitats of temperate maritime uplands. Bulk deposition chemistry, soil carbon content, soil solution chemistry, soil temperature and soil moisture content were monitored over a 5 year period. Results were used to assess spatial variability in soil solution N and to investigate the factors and processes driving this variability. Highest soil solution inorganic N concentrations were found in the alpine soils at the top of the hillslope. Soil carbon stock, soil solution dissolved organic carbon (DOC) and factors representing site hydrology were the best predictors of NO(3)(-) concentration, with highest concentrations at low productivity sites with low DOC and freely-draining soils. These factors act as proxies for changing net biological uptake and soil/water contact time, and therefore support the hypothesis that spatial variations in soil solution NO(3)(-) are controlled by habitat N retention capacity. Soil percent carbon was a better predictor of soil solution inorganic N concentration than mass of soil carbon. NH(4)(+) was less affected by soil hydrology than NO(3)(-) and showed the effects of net mineralization inputs, particularly at Racomitrium heath and peaty sites. Soil solution dissolved organic N concentration was strongly related to both DOC and temperature, with a stronger temperature effect at more productive sites. Due to the spatial heterogeneity in N leaching potential, a fine-scale approach to assessing surface water vulnerability to N leaching is recommended over the broad scale, critical loads approach currently in use, particularly for sensitive areas. Copyright © 2012 Elsevier B.V. All rights reserved.

Methodology for estimation of time-dependent surface heat flux due to cryogen spray cooling.

PubMed

Tunnell, James W; Torres, Jorge H; Anvari, Bahman

2002-01-01

Cryogen spray cooling (CSC) is an effective technique to protect the epidermis during cutaneous laser therapies. Spraying a cryogen onto the skin surface creates a time-varying heat flux, effectively cooling the skin during and following the cryogen spurt. In previous studies mathematical models were developed to predict the human skin temperature profiles during the cryogen spraying time. However, no studies have accounted for the additional cooling due to residual cryogen left on the skin surface following the spurt termination. We formulate and solve an inverse heat conduction (IHC) problem to predict the time-varying surface heat flux both during and following a cryogen spurt. The IHC formulation uses measured temperature profiles from within a medium to estimate the surface heat flux. We implement a one-dimensional sequential function specification method (SFSM) to estimate the surface heat flux from internal temperatures measured within an in vitro model in response to a cryogen spurt. Solution accuracy and experimental errors are examined using simulated temperature data. Heat flux following spurt termination appears substantial; however, it is less than that during the spraying time. The estimated time-varying heat flux can subsequently be used in forward heat conduction models to estimate temperature profiles in skin during and following a cryogen spurt and predict appropriate timing for onset of the laser pulse.

Analysis of three variables in sampling solutions used to assay bacteria of hands: type of solution, use of antiseptic neutralizers, and solution temperature.

PubMed Central

Larson, E L; Strom, M S; Evans, C A

1980-01-01

Tests were performed using the sterile bag technique to determine the effects of type of sampling solution, use of antiseptic neutralizers, and solution temperature on the detection and quantitation of bacteria on hands. Using paired hand cultures, three sampling solutions were compared: quarter-strength Ringer solution, a phosphate buffer containing Triton X-100, and the same buffer containing antiseptic neutralizers. The phosphate buffer containing Triton X-100 was significantly better than quarter-strength Ringer solution in mean bacterial yield; the neutralizer-containing sampling solution was slightly better than Triton X-100-containing solution, although differences were not significant at the P = 0.05 level. Temperature (6 or 23 degrees C) of the sampling solution showed no consistent effect on bacterial yield from hands tested with the fluid containing neutralizers. PMID:7012171

Low-temperature dielectric behavior of Nb{sub 2}O{sub 5}-SiO{sub 2} solid solutions.

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

Choosuwan, H.; Guo, R.; Bhalla, A. S.

2003-03-01

Dielectric properties of Nb{sub 2}O{sub 5}(0.92):SiO{sub 2}(0.08) ceramic were measured in the temperature range of 10-300 K by the cryostat system. Frequency-dependent dielectric loss suggests the relaxation behavior of this material. The relaxation mechanism was analyzed by the Arrhenius relationship and the Cole-Cole plot. Calculated distribution of relaxation time reveals deviation from the pure Debye relaxation.

Nucleation and growth of hydroxyapatite on arc-deposited TiO2 surfaces studied by quartz crystal microbalance with dissipation

NASA Astrophysics Data System (ADS)

Lilja, Mirjam; Butt, Umer; Shen, Zhijian; Bjöörn, Dorota

2013-11-01

Understanding of nucleation and growth kinetics of biomimetically deposited hydroxyapatite (HA) on crystalline TiO2 surfaces is important with respect to the application and performance of HA as functional implant coatings. Arc-evaporation was used to deposit TiO2 coatings dominated by anatase phase, rutile phase or their mixtures. Subsequent formation of HA from phosphate buffered saline solution (PBS) was investigated in real-time using in situ quartz crystal microbalance with dissipation technique (QCM-D). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to characterize the presence, morphology and crystal structure of TiO2 coatings and the formed HA. Increasing temperature of the PBS, increasing flow rate and applying a higher ion concentration in solution were found to accelerate HA nucleation process and hence affect growth kinetics. Lower PBS temperature resulted in the formation of HA coatings with flake-like morphology and increasing HA porosity. All TiO2 coatings under study enabled HA formation at body temperature, while in contrast Ti reference surfaces only supported HA nucleation and growth at elevated temperatures. QCM-D technique is a powerful tool for studying the impact of process parameters during biomimetic coating deposition on coating structure evolution in real time and provides valuable information for understanding, optimizing as well as tailoring the biomimetic HA growth processes.