Sample records for dehydration condensation reaction

  1. Free energy landscape for glucose condensation and dehydration reactions in dimethyl sulfoxide and the effects of solvent.

    PubMed

    Qian, Xianghong; Liu, Dajiang

    2014-03-31

    The mechanisms and free energy surfaces (FES) for the initial critical steps during proton-catalyzed glucose condensation and dehydration reactions were elucidated in dimethyl sulfoxide (DMSO) using Car-Parrinello molecular dynamics (CPMD) coupled with metadynamics (MTD) simulations. Glucose condensation reaction is initiated by protonation of C1--OH whereas dehydration reaction is initiated by protonation of C2--OH. The mechanisms in DMSO are similar to those in aqueous solution. The DMSO molecules closest to the C1--OH or C2--OH on glucose are directly involved in the reactions and act as proton acceptors during the process. However, the energy barriers are strongly solvent dependent. Moreover, polarization from the long-range electrostatic interaction affects the mechanisms and energetics of glucose reactions. Experimental measurements conducted in various DMSO/Water mixtures also show that energy barriers are solvent dependent in agreement with our theoretical results. PMID:24631668

  2. Spatiotemporal evolution of dehydration reactions in subduction zones (Invited)

    NASA Astrophysics Data System (ADS)

    Padron-Navarta, J.

    2013-12-01

    Large-scale deep water cycling takes place through subduction zones in the Earth, making our planet unique in the solar system. This idiosyncrasy is the result of a precise but unknown balance between in-gassing and out-gassing fluxes of volatiles. Water is incorporated into hydrous minerals during seafloor alteration of the oceanic lithosphere. The cycling of volatiles is triggered by dehydration of these minerals that release fluids from the subducting slab to the mantle wedge and eventually to the crust or to the deep mantle. Whereas the loci of such reactions are reasonably well established, the mechanisms of fluid migration during dehydration reactions are still barely known. One of the challenges is that dehydration reactions are dynamic features evolving in time and space. Experimental data on low-temperature dehydration reactions (i.e. gypsum) and numerical models applied to middle-crust conditions point to a complex spatiotemporal evolution of the dehydration process. The extrapolation of these inferences to subduction settings has not yet been explored but it is essential to understand the dynamism of these settings. Here I propose an alternative approach to tackle this problem through the textural study of high-pressure terrains that experienced dehydration reactions. Spatiotemporal evolution of dehydration reactions should be recorded during mineral nucleation and growth through variations in time and space of the reaction rate. Insights on the fluid migration mechanism could be inferred therefore by noting changes in the texture of prograde assemblages. The dehydration of antigorite in serpentinite is a perfect candidate to test this approach as it releases a significant amount of fluid and produces a concomitant porosity. Unusual alternation of equilibrium and disequilibrium textures observed in Cerro del Almirez (Betic Cordillera, S Spain)[1, 2] attest for a complex fluid migration pattern for one of the most relevant reactions in subduction zones. This opens the possibility to correlate textural features recorded in high-pressure terrains with the physical fingerprint of dehydration reactions such as fluid flow rates and eventually seismicity or tremor. References [1] Padrón-Navarta, J. A., Tommasi, A., Garrido, C. J., López Sánchez-Vizcaíno, V., Gómez-Pugnaire, M. T., Jabaloy, A. & Vauchez, A. (2010). Fluid transfer into the wedge controlled by high-pressure hydrofracturing in the cold top-slab mantle. Earth and Planetary Science Letters 297, 271-286. [2] Padrón-Navarta, J. A., López Sánchez-Vizcaíno, V., Garrido, C. J. & Gómez-Pugnaire, M. T. (2011). Metamorphic Record of High-pressure Dehydration of Antigorite Serpentinite to Chlorite Harzburgite in a Subduction Setting (Cerro del Almirez, Nevado-Filábride Complex, Southern Spain). Journal of Petrology 52, 2047-2078.

  3. Dehydration

    MedlinePLUS

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  4. Effect of Dehydration Reaction on Serpentinite Deformation in Torsion

    NASA Astrophysics Data System (ADS)

    Vinciguerra, S.; Trovato, C.; Meredith, P. G.; Benson, P. M.; Hirose, T.; Bystricky, M.; Stünitz, H.; Kunze, K.

    2003-12-01

    Dehydration of serpentine to olivine, talc and water during deformation is critical for understanding the possible localization of deformation into shear zones and the generation of earthquakes along subduction zones. In order to investigate the effect of the dehydration reaction on the strength and ductility of serpentinite, torsion experiments were performed using a Paterson high PT torsion rig at constant shear strain rates of 10-4 to 10-5 s-1, temperatures of 550 to 750 ° C and a confining pressure of 300 MPa, to local shear strains up to ? = 3. We deformed two types of serpentinite: antigorite from Val Malenco, Italy, a high-temperature phase of serpentine (stable at T <500 ° C), and lizardite from Elba, Italy, a low-temperature phase of serpentine (stable at T <400 ° C). Most of the samples were shaped in dog-bone geometry with a central hole along their axial direction which acted as a fluid conduit, enabling an easy escape for any released fluid during the dehydration reaction. We also deformed solid bone-shaped specimens to compare the mechanical behavior of solid and hollow specimens. In both cases, porous alumina spacers were placed on both end sides of specimen and led to the atmosphere through the pore pressure line. Thus our experiments were performed under drained conditions. Antigorite deformed in the semi-brittle field at the run conditions. Visible faults formed probably due to reaction-induced fracturing, and the stress started to drop just after the initial peak stress ( ˜350 MPa at 650 to 700 ° C and ˜280 MPa at 750 ° C). Highly comminuted grains with various sizes along the faults were identified as partially dehydrated antigorite (H2O ˜6 wt%) at 650 ° C and olivine and talc at >700 ° C. Mechanical behavior after the peak stress is thought to occur by cataclastic flow, possibly assisted by diffusion mass transfer processes of these fine-grained reactant minerals. We have also investigated the effect of pre-heating on the strength of antigorite. The peak strength of a sample pre-heated at 750 ° C for 3 hr and then deformed at 700 ° C is 70 MPa lower than a sample deformed directly at 700 ° C. This stress reduction occurred due to the presence of a mechanically weaker reaction product (talc) rather than elevated pore pressure because the sample was deformed under completely drained conditions. By contrast, a solid sample was weaker than hollow ones by ˜100 MPa, mainly due to low permeability of the serpentinite. Excess fluid pressure in solid specimens leads to a drop in the effective pressure and appears to have enhanced the dehydration reaction along micro-fractures. Our data shows that dehydration weakening of serpentinite is caused not as much because of excess pore pressure but more because of the weaker mineral assemblages from the reaction. In contrast to semi-brittle faulting in antigorite, deformation of lizardite at 550 ° C to a bulk shear strain of 0.9 was widely distributed, showing typical ductile microstructures such as boudinage and S-C fabric. A well developed secondary foliation (C-plane) and strong lattice preferred orientations of lizardite grains were observed close to the localized shear zones. After the initial peak stress, steady stress values of 250 MPa were measured. We intend to focus on how the localized zones evolve and how the mechanical response changes with increasing shear strain during the reaction.

  5. Dehydrative cross-coupling reactions of allylic alcohols with olefins.

    PubMed

    Gumrukcu, Yasemin; de Bruin, Bas; Reek, Joost N H

    2014-08-25

    The direct dehydrative activation of allylic alcohols and subsequent cross-coupling with alkenes by using palladium catalyst containing a phosphoramidite ligand is described. The activation of the allyl alcohol does not require stoichiometric additives, thus allowing clean, waste-free reactions. The scope is demonstrated by application of the protocol to a series allylic alcohols and vinyl arenes, leading to variety of 1,4-diene products. Based on kinetic studies, a mechanism is proposed that involves a palladium hydride species that activates the allyl alcohol to form the allyl intermediate. PMID:25113437

  6. The first dehydration and the competing reaction pathways of glucose homogeneously and heterogeneously catalyzed by acids.

    PubMed

    Lin, Xufeng; Qu, Yuanyuan; Lv, Yanhong; Xi, Yanyan; Phillips, David Lee; Liu, Chenguang

    2013-02-28

    The dehydration mechanisms for glucose in ?-pyranose (BP) and in open-chain (OC) forms, catalyzed by acids homogeneously and heterogeneously, were investigated using density functional and two-layer ONIOM calculations. The first dehydration reaction and competing reaction pathways are the main focus of the present study. The energetics of five dehydration and two isomerization pathways were examined for the protonated form of BP in acidic aqueous solutions and the most favorable pathway of these was found to be the dehydration at the anomeric site. No dehydration pathway of OC glucose is favored over its isomerization to BP or to fructose. The relative ease of dehydration over isomerization depends on the selection of the reaction media for the protonated form of BP. These two reaction pathways catalyzed by a surface Brönsted acid site were then examined and the isomerization pathway was found to be more favorable than dehydration at the anomeric site on a surface acid site. These mechanistic insights provide an important guide for the catalyst design/selection of the reaction media for glucose dehydration. PMID:23340797

  7. Water incorporation in NAMs after antigorite and chlorite dehydration reactions

    NASA Astrophysics Data System (ADS)

    Padrón-Navarta, José Alberto; Hermann, Jörg

    2014-05-01

    Subduction zones play a fundamental role in the deep water cycle making the Earth unique among other terrestrial planets. Water is incorporated into hydrous minerals during seafloor alteration of the oceanic lithosphere. During subduction of the oceanic lithosphere, dehydration of these hydrous minerals produces a fluid phase. A part of this fluid phase will be recycled back to the Earth's surface through hydrothermal aqueous fluids or through hydrous arc magmas, whereas another part of the water will be transported to the deep mantle by Nominally Anhydrous Minerals (NAMs) such as olivine, pyroxene and garnet. The partitioning of water between these two processes is crucial for our understanding of the mantle-scale water recycling in the Earth. This can be investigated experimentally under water-saturated conditions because this situation is met during dehydration reactions. However relatively low temperature conditions for such reactions make challenging these experiments. An alternative can be found in the natural record. The Alpine Betic-Rif orogen together with Central and Western Alps offer an invaluable diversity of ultramafic lenses that record a significant range of pressure-temperature and cooling rates. Hence these samples portray an excellent data set of 24 samples to survey the transfer of fluids from hydrous phases (brucite, antigorite and chlorite) to NAMs (olivine, orthopyroxene, clinopyroxene and garnet). Well-studied samples from these localities have been selected for water measurement using FTIR spectroscopy. The selected suite comprises the following high-pressure peridotite outcrops: Malenco serpentinite, Cerro del Almirez (1.6-1.9 GPa and 680-710ºC), Alpe Arami (3.2 GPa and 840ºC), Cima di Gagnone (3.0 GPa and 750-800ºC) and Alpe Albion (0.6 GPa and 730ºC). The infrared signature of olivine in all localities contains water (hydroxyl groups) associated to intrinsic defects (mostly point defects related to Ti4+) and extrinsic submicroscopic hydrous lamellae (titanoclinohumite). In the following only water contents related to intrinsic defects are reported. At low temperature (400-450 ºC) the spectra of olivine coexisting with antigorite are dominated by OH associated to silica-vacancies and contains 12-20 wt. ppm H2O (using site-specific infrared OH absorption coefficients from [1]). Olivine in equilibrium with orthopyroxene and chlorite formed after the antigorite breakdown (650-700 ºC) at high pressure (1.6-1.9 GPa) from Cerro del Almirez contains 14-17 ppm and is associated to Ti4+ and abundant extrinsic defects. Surprisingly the associated orthopyroxene is nearly dry (1-3 wt. ppm) resulting in D[opx/ol] 1. After chlorite breakdown (750-800ºC) olivine contains 21-68 wt. ppm H2O. In summary there is a systematic correlation between PT conditions and water content in olivine and orthopyroxene. The dependence is however different for both resulting in significant changes in the water partition coefficient. This dataset represents a first step in the quantification of the water budget in the slab and in the mantle wedge of NAMs coexisting with hydrous phases and after their breakdown. [1] Kovacs, I., O'Neill, H.S.C., Hermann, J., Hauri, E.H., 2010. Site-specific infrared O-H absorption coefficients for water substitution into olivine. Am. Miner. 95, 292-299.

  8. Subduction factory 2. Are intermediate-depth earthquakes in subducting slabs linked to metamorphic dehydration reactions?

    Microsoft Academic Search

    Bradley R. Hacker; Simon M. Peacock; Geoffrey A. Abers; Stephen D. Holloway

    2003-01-01

    New thermal-petrologic models of subduction zones are used to test the hypothesis that intermediate-depth intraslab earthquakes are linked to metamorphic dehydration reactions in the subducting oceanic crust and mantle. We show that there is a correlation between the patterns of intermediate-depth seismicity and the locations of predicted hydrous minerals: Earthquakes occur in subducting slabs where dehydration is expected, and they

  9. (100) facets of ?-Al2O3: the active surfaces for alcohol dehydration reactions

    SciTech Connect

    Kwak, Ja Hun; Mei, Donghai; Peden, Charles HF; Rousseau, Roger J.; Szanyi, Janos

    2011-05-01

    Temperature programmed desorption (TPD) of ethanol, and methanol dehydration reaction were studied on ?-Al2O3 in order to identify the catalytic active sites for alcohol dehydration reactions. Two high temperature (> 473 K) desorption features were observed following ethanol adsorption. Samples calcined at T?473 K displayed a desorption feature in the 523-533 K temperature range, while those calcined at T ? 673 K showed a single desorption feature at 498 K. The switch from the high to low temperature ethanol desorption correlated well with the dehydroxylation of the (100) facets of ?-Al2O3 that was predicted at 550 K DFT calculations. Theoretical DFT simulations of the mechanism of dehydration. on clean and hydroxylated ?-Al2O3(100) surfaces, find that a concerted elimination of ethylene from an ethanol molecule chemisorbed at an Al3+ pentacoordinated site is the rate limiting step for catalytic cycle on both surfaces. Furthermore, titration of the pentacoordinate Al3+ sites on the (100) facets of ?-Al2O3 by BaO completely turned off the methanol dehydration reaction activity. These results unambiguously demonstrate that only the (100) facets on ?-Al2O3 are the catalytic active surfaces for alcohol dehydration.

  10. Synthesis of biaryls via AlCl3 catalyzed domino reaction involving cyclization, dehydration, and oxidation.

    PubMed

    Narender, Tadigoppula; Sarkar, Satinath; Rajendar, Kandikonda; Tiwari, Sriniwas

    2011-12-01

    A new chemical access has been developed to synthesize biaryls from substituted acetophenones, phenylacetones, dihydrochalcone, and 2-acetylnaphthalene in reasonably good yields at room temperature via a domino reaction sequence of AlCl(3) catalyzed cyclization, dehydration, and then oxidation. PMID:22040063

  11. Will water act as a photocatalyst for cluster phase chemical reactions? Vibrational overtone-induced dehydration reaction of methanediol

    SciTech Connect

    Kramer, Zeb C.; Takahashi, Kaito; Skodje, Rex T. [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215 (United States); Vaida, Veronica [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215 (United States); CIRES, University of Colorado, Boulder, Colorado 80309 (United States)

    2012-04-28

    The possibility of water catalysis in the vibrational overtone-induced dehydration reaction of methanediol is investigated using ab initio dynamical simulations of small methanediol-water clusters. Quantum chemistry calculations employing clusters with one or two water molecules reveal that the barrier to dehydration is lowered by over 20 kcal/mol because of hydrogen-bonding at the transition state. Nevertheless, the simulations of the reaction dynamics following OH-stretch excitation show little catalytic effect of water and, in some cases, even show an anticatalytic effect. The quantum yield for the dehydration reaction exhibits a delayed threshold effect where reaction does not occur until the photon energy is far above the barrier energy. Unlike thermally induced reactions, it is argued that competition between reaction and the irreversible dissipation of photon energy may be expected to raise the dynamical threshold for the reaction above the transition state energy. It is concluded that quantum chemistry calculations showing barrier lowering are not sufficient to infer water catalysis in photochemical reactions, which instead require dynamical modeling.

  12. Thermal dehydration reactions characterized by combined measurements of electrical conductivity and elastic wave velocities

    NASA Astrophysics Data System (ADS)

    Popp, T.; Kern, H.

    1993-11-01

    Combined laboratory measurements of seismic velocities and electrical conductivity as a function of PT and drainage conditions have been performed on various rocks containing hydrous minerals. This paper presents experimental results for evaporite rocks containing gypsum (CaSO4 x 2H2O) and carnallite (KMgCl3 x 6H2O) and for serpentinite. The experiments on the evaporite rocks were carried out in a triaxial cell in the range 20-130 C and 5.0-24.0 MPa confining pressure. The measurements on serpentinite covered the range 20-750 C at pressures of up to 200 MPa and were performed in a cubic pressure apparatus. The thermally induced onset of dehydration was indicated by the pronounced discontinuous behaviour of conductivity, corresponding to a marked drop in the elastic wave velocities. The respective Poisson ratios were inversely correlated with permeability and seem to be a sensitive parameter to describe the reaction-related variations of pore space. The seismic properties can be satisfactory modelled by using the self-consistent approximation of O'Connell and Budiansky, illustrating the effects of variations in pore space and saturation. The dehydration behavior of the various hydrous rock types was found to be different because the changes in the rock physical properties are closely linked to the internally created pore fluid, to the changes in the porosity and pore geometry, and to the resulting pore pressure. Progressive thermal dehydration reactions induce an opening of pore space accompanied by lowered saturation conditions whereby the rate of fluid release depends mainly on temperature and also on the drainage conditions of the system. Our findings, as reflected by the variations in the geophysical parameters, may be of importance for the interpretation of natural dehydration processes in the crust caused by prograde metamorphism.

  13. Investigating the Role of Dehydration Reactions in Subduction Zone Pore Pressures Using Newly-Developed Permeability-Porosity Relationships

    NASA Astrophysics Data System (ADS)

    Screaton, E.; Daigle, H.; James, S.; Meridth, L.; Jaeger, J. M.; Villaseñor, T. G.

    2014-12-01

    Dehydration reactions are linked to shallow subduction zone deformation through excess pore pressures and their effect on mechanical properties. Two reactions, the transformation of smectite to illite and of opal-A to opal-CT and then to quartz, can occur relatively early in the subduction process and may affect the propagation of the plate boundary fault, the updip limit of velocity-weakening frictional paper, and tsunamigenesis. Due to large variations between subduction zones in heat flow, sedimentation rates, and geometries, dehydration location may peak prior to subduction to as much as 100 km landward of the deformation front. The location of the dehydration reaction peak relative to when compaction occurs, causes significant differences in pore pressure generation. As a result, a key element to modeling excess pore pressures due to dehydration reactions is the assumed relationship between permeability and porosity. Data from Integrated Ocean Drilling Program (IODP) drilling of subduction zone reference sites were combined with previously collected results to develop relationships for porosity-permeability behavior for various sediment types. Comparison with measurements of deeper analog data show that porosity-permeability trends are maintained through burial and diagenesis to porosities <10%, suggesting that behavior observed in shallow samples is informative for predicting behavior at depth following subduction. We integrate these permeability-porosity relationships, compaction behavior, predictions of temperature distribution, kinetic expressions for smectite and opal-A dehydration, into fluid flow models to examine the role of dehydration reactions in pore pressure generation.

  14. Metamorphic dehydration reactions control the location of intermediate-depth seismicity

    NASA Astrophysics Data System (ADS)

    van Keken, Peter E.; Kita, Saeko; Nakajima, Junichi; Abers, Geoff; Hacker, Brad

    2013-04-01

    The cause of intermediate-depth seismicity in subduction zones is not well understood. The viability of proposed mechanisms, that include dehydration embrittlement, shear instablities, and the presence of fluids in general, depends significantly on local conditions, including pressure, temperature, and composition. A number of high resolution seismic studies have improved the location of earthquakes within the slab in Japan, Alaska and Cascadia. Intriguingly, the warm subduction zones of Nankai and Cascadia show that intermediate depth seismicity is located below the oceanic crust. In contrast, the colder subduction zones Alaska, Tohoku and Hokkaido have the upper plane of seismicity confined to the subducting crust, with a systematic deepening of the seismic belt with respect to the top of the slab with depth. We use high resolution thermal-petrological models to determine the metamorphic facies in the downgoing slab and to identify the main phase changes that cause dehydration. In Alaska and Northern Japan, the seismicity occurs at, or at shallower depths than, the blueschist-out boundary. In Nankai and Cascadia the seismicity disappears above the antigorite-out boundary. Seismicity in the lower plane of the double seismic zone in Northern Japan also occurs at pressures and temperatures below the antigorite-out boundary. These observations strongly suggest that intermediate-depth seismicity is limited by the first major dehydration reaction in the crust and mantle and that fluids liberated by this phase change are primarily responsible for causing the earthquakes.

  15. The influence of dehydration reactions on the mechanical behavior of antigorite: Implications for understanding strain localization and seismicity

    NASA Astrophysics Data System (ADS)

    Hirth, G.; Chernak, L. J.

    2011-12-01

    We conducted a series of deformation experiments to further investigate the role dehydration embrittlement on the frictional behavior and deformation style of serpentintes. Our previous experiments on antigorite show that deformation localizes within its stability field and suggest that syn-deformational antigorite dehydration does not lead directly to stick-slip instabilities (Chernak and Hirth, 2010; 2011), but may promote slow, stable slip events. Motivated by these results, we conducted additional axial compression deformation experiments on antigorite serpentinite at temperatures of 400 to 700°C and pressures of 0.5 to 1.5 GPa to investigate deformation behavior at conditions near the thermal stability of antigorite. All experiments are conducted under un-drained conditions. We find that deformation localizes in all samples except those deformed at 700°C and 1.5 GPa. Distributed behavior may be promoted by (a) the lack of volume change during dehydration and/or (b) an inhibition of grain-scale "over-pressure" due to the high permeability associated with the large extent of reaction that occurs prior to deformation. Sample strength decreases after only ~1% reaction, indicating that initial weakening results from a reduction in effective pressure owing to fluid release at the onset of dehydration. The generation of porosity and fine-grained reaction products result in further weakening after greater extents of reaction. At pressure/temperature conditions near the thermal limit of antigorite stability we observe the onset of dehydration and weakening associated with dilatant crack growth in antigorite. We will discuss the implications of these results for understanding mechanisms of intermediate depth seismicity and the role of dehydration reactions in promoting strain localization.

  16. POLLUTION PREVENTION IN INDUSTRIAL CONDENSATION REACTIONS

    EPA Science Inventory

    The objective of this project is to develop heterogeneous acid-base catalysts to increase the economic and environmental performance of the current homogeneous catalysts used to make industrially important condensation products. Such products include methyl isobutyl ketone ...

  17. A DFT based equilibrium study on the hydrolysis and the dehydration reactions of MgCl2 hydrates

    NASA Astrophysics Data System (ADS)

    Smeets, B.; Iype, E.; Nedea, S. V.; Zondag, H. A.; Rindt, C. C. M.

    2013-09-01

    Magnesium chloride hydrates are characterized as promising energy storage materials in the built-environment. During the dehydration of these materials, there are chances for the release of harmful HCl gas, which can potentially damage the material as well as the equipment. Hydrolysis reactions in magnesium chloride hydrates are subject of study for industrial applications. However, the information about the possibility of hydrolysis reaction, and its preference over dehydration in energy storage systems is still ambiguous at the operating conditions in a seasonal heat storage system. A density functional theory level study is performed to determine molecular structures, charges, and harmonic frequencies in order to identify the formation of HCl at the operating temperatures in an energy storage system. The preference of hydrolysis over dehydration is quantified by applying thermodynamic equilibrium principles by calculating Gibbs free energies of the hydrated magnesium chloride molecules. The molecular structures of the hydrates (n = 0, 1, 2, 4, and 6) of MgCl2 are investigated to understand the stability and symmetry of these molecules. The structures are found to be noncomplex with almost no meta-stable isomers, which may be related to the faster kinetics observed in the hydration of chlorides compared to sulfates. Also, the frequency spectra of these molecules are calculated, which in turn are used to calculate the changes in Gibbs free energy of dehydration and hydrolysis reactions. From these calculations, it is found that the probability for hydrolysis to occur is larger for lower hydrates. Hydrolysis occurring from the hexa-, tetra-, and di-hydrate is only possible when the temperature is increased too fast to a very high value. In the case of the mono-hydrate, hydrolysis may become favorable at high water vapor pressure and at low HCl pressure.

  18. Investigation of condensed and early stage gas phase hypergolic reactions

    NASA Astrophysics Data System (ADS)

    Dennis, Jacob Daniel

    Traditional hypergolic propellant combinations, such as those used on the space shuttle orbital maneuvering system first flown in 1981, feature hydrazine based fuels and nitrogen tetroxide (NTO) based oxidizers. Despite the long history of hypergolic propellant implementation, the processes that govern hypergolic ignition are not well understood. In order to achieve ignition, condensed phase fuel and oxidizer must undergo simultaneous physical mixing and chemical reaction. This process generates heat, intermediate condensed phase species, and gas phase species, which then may continue to react and generate more heat until ignition is achieved. The process is not well understood because condensed and gas phase reactions occur rapidly, typically in less than 200 ?s, on much faster timescales than traditional diagnostic methods can observe. A detailed understanding of even the gas phase chemistry is lacking, but is critical for model development. Initial research has provided confidence that a study of condensed phase hypergolic reactions is useful and possible. Results obtained using an impinging jet apparatus have shown a critical residence time of 0.3 ms is required for the reaction between monomethylhydrazine (MMH) and red fuming nitric acid (RFNA, ~85% HNO3 + 15% N2O4) to achieve conditions favorable for ignition. This critical residence time spans the time required for liquid phase reactions to occur at the fuel/oxidizer interface and can give some insight into the reaction rates for this propellant combination. Experiments performed in a forced mixing constant volume reactor have demonstrated that the chamber pressurization rate for MMH/RFNA can be significantly reduced by diluting the MMH with deionized water. This result indicates that propellant dilution can slow the chemical reaction rates to occur over observable time scales. The research described in this document consists of two efforts that contribute knowledge to the propulsion community regarding the hypergolic liquid propellant combination of MMH and RFNA or pure nitric acid. The first and most important effort focuses on furthering the understanding of condensed phase reactions between MMH and nitric acid. To accomplish this goal diluted MMH and nitric acid were studied in a Fourier transform infrared spectrometer. By tracking the generation or destruction of specific chemical species in the reacting fluid we can measure the reaction progress as a function of reactant concentration and temperature. This work provides the propulsion community with a quantitative global condensed phase reaction rate equation for MMH/nitric acid. The second effort focuses on improving understanding the recently proposed gas phase hypergolic reaction mechanisms using a streak camera based ultraviolet and visible spectrometer. The time resolution on the streak camera system allows for detailed investigation of the pre-ignition and early stage gas phase species present during the reaction between MMH and RFNA.

  19. Detonation Reaction Zones in Condensed Explosives

    SciTech Connect

    Tarver, C M

    2005-07-14

    Experimental measurements using nanosecond time resolved embedded gauges and laser interferometric techniques, combined with Non-Equilibrium Zeldovich--von Neumann--Doring (NEZND) theory and Ignition and Growth reactive flow hydrodynamic modeling, have revealed the average pressure/particle velocity states attained in reaction zones of self-sustaining detonation waves in several solid and liquid explosives. The time durations of these reaction zone processes is discussed for explosives based on pentaerythritol tetranitrate (PETN), nitromethane, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), triaminitrinitrobenzene(TATB) and trinitrotoluene (TNT).

  20. Direct and Indirect Determinations of Elementary Rate Constants H + O2: Chain Branching; the Dehydration of tertiary-Butanol; the Retro Diels-Alder Reaction of Cyclohexene; the Dehydration of Isopropanol

    NASA Astrophysics Data System (ADS)

    Heyne, Joshua S.

    Due to growing environmental concern over the continued use of fossil fuels, methods to limit emissions and partially replace fossil fuel use with renewable biofuels are of considerable interest. Developing chemical kinetic models for the chemistry that affects combustion properties is important to understanding how new fuels affect combustion energy conversion processes in transportation devices. This thesis reports the experimental study of several important reactions (the H + O2 branching reaction, the key decomposition reactions of tertiary-butanol, the dehydration reaction of isopropanol, and the retro Diels-Alder reaction of cyclohexene) and develops robust analysis methods to estimate the absolute uncertainties of specific elementary rate constants derived from the experimental data. In the study of the above reactions, both a direct and indirect rate constant determination technique with associated uncertainty estimation methodologies are developed. In the study of the decomposition reactions, a direct determination technique is applied to experimental data gathered in preparation of this thesis. In the case of the dehydration reaction of tertiary-butanol and the retro Diels-Alder reaction of cyclohexene, both of which are used as internal standards for relative rate studies (Herzler et al. 1997) and chemical thermometry (Rosado-Reyes et al. 2013) , analysis showed an ˜20 K difference in the reaction rate between the reported results and the previous recommendations. In light of these discrepancies, an uncertainty estimation of previous recommendations illuminated an uncertainty of at least 20 K for the dehydration reaction of tertiary-butanol and the retro Diels-Alder reaction of cyclohexene, thus resolving the discrepancies. The determination of the H + O2 branching reaction and decomposition reactions of isopropanol used an indirect determination technique. The uncertainty of the H + O2 branching reaction rate is shown to be underestimated by previous analysis (Hong et al. 2011, Turanyi, et al. 2012), and the dehydration reaction of isopropanol is shown to be four times faster than theoretical predictions. Analyses of uncertainties for these reactions show that a linearized local sensitivity analysis does not completely capture uncertainties. Appendix B in this thesis includes additional work conducted during the preparation of this thesis, namely the measurement of derived cetane numbers for jet fuel surrogates.

  1. Porous magnesium carboxylate framework: synthesis, X-ray crystal structure, gas adsorption property and heterogeneous catalytic aldol condensation reaction.

    PubMed

    Saha, Debraj; Sen, Rupam; Maity, Tanmoy; Koner, Subratanath

    2012-06-28

    A new three-dimensional alkaline-earth metal-organic framework (MOF) compound, [Mg(Pdc)(H(2)O)](n) (1) (H(2)Pdc = pyridine-2,5-dicarboxylic acid), has been synthesized and structurally characterized by single crystal X-ray diffraction analysis. Compound 1 features a 3D porous framework afforded by the Mg(2)-diad centers through formation of interconnected chair like structural motifs. A nitrogen adsorption study confirms the microporosity of compound 1 with a BET surface area of 211 ± 12 m(2) g(-1). Upon dehydration, the BET surface area of 1 is enhanced to a value of 463 ± 36 m(2) g(-1) due to removal of coordinated water molecule. After rehydration, the compound reverts to its original form as evidenced by powder X-ray diffraction and IR spectroscopic analysis and N(2) sorption measurement. Compound 1 retains its pore structure with a variable BET surface area in several cycles of dehydration and rehydration processes indicating robustness of the framework in [Mg(Pdc)(H(2)O)](n) (1). Compound 1 catalyzes the aldol condensation reactions of various aromatic aldehydes with acetone and cyclohexanone in heterogeneous conditions. Notably, the catalytic activity of the compound is enhanced upon dehydration. The catalyst can be recycled and reused several times without significant loss of activity. PMID:22584602

  2. On the reaction mechanism of tirapazamine reduction chemistry: unimolecular N-OH homolysis, stepwise dehydration, or triazene ring-opening.

    PubMed

    Yin, Jian; Glaser, Rainer; Gates, Kent S

    2012-03-19

    The initial steps of the activation of tirapazamine (TPZ, 1, 3-amino-1,2,4-benzotriazine 1,4-N,N-dioxide) under hypoxic conditions consist of the one-electron reduction of 1 to radical anion 2 and the protonation of 2 at O(N4) or O(N1) to form neutral radicals 3 and 4, respectively. There are some questions, however, as to whether radicals 3 and/or 4 will then undergo N-OH homolyses 3 ? 5 + ·OH and 4 ? 6 + ·OH or, alternatively, whether 3 and/or 4 may react by dehydration and form aminyl radicals via 3 ? 11 + H(2)O and 4 ? 12 + H(2)O or phenyl radicals via 3 ? 17 + H(2)O. These outcomes might depend on the chemistry after the homolysis of 3 and/or 4, that is, dehydration may be the result of a two-step sequence that involves N-OH homolysis and formation of ·OH aggregates of 5 and 6 followed by H-abstraction within the ·OH aggregates to form hydrates of aminyls 11 and 12 or of phenyl 17. We studied these processes with configuration interaction theory, perturbation theory, and density functional theory. All stationary structures of OH aggregates of 5 and 6, of H(2)O aggregates of 11, 12, and 17, and of the transition state structures for H-abstraction were located and characterized by vibrational analysis and with methods of electron and spin-density analysis. The doublet radical 17 is a normal spin-polarized radical, whereas the doublet radicals 11 and 12 feature quartet instabilities. The computed reaction energies and activation barriers allow for dehydration in principle, but the productivity of all of these channels should be low for kinetic and dynamic reasons. With a view to plausible scenarios for the generation of latent aryl radical species without dehydration, we scanned the potential energy surfaces of 2-4 as a function of the (O)N1-Y (Y = C5a, N2) and (O)N4-Z (Z = C4a, C3) bond lengths. The elongation of any one of these bonds by 0.5 Å requires less than 25 kcal/mol, and this finding strongly suggests the possibility of bimolecular reactions of the spin-trap molecules with 2-4 concomitant with triazene ring-opening. PMID:22390168

  3. Forward Analyses of Dehydration Reactions in Mafic Rocks Along the P-T Trajectories of the Subducting Slabs

    NASA Astrophysics Data System (ADS)

    Kuwatani, T.; Okamoto, A.; Toriumi, M.

    2005-12-01

    Fluids in the subduction zone play an important role in magmatism, metamorphism, and mechanical processes involving seismic activity. Additionally, recent geophysical researches found low-frequency tremors which may be related to the movement of fluid (Obara, 2002) and a zone of high Poisson_fs ratio which reflects high pore fluid pressure (Kodaira et al.,2004) in the Southwest Japan fore-arc. It is widely accepted that these fluids are supplied by the dehydration of hydrous metamorphic minerals in the subducting oceanic plate. Although many previous studies attempted to estimate the water content of the subducting oceanic crust experimentally and theoretically (e.g., Schmidt and Poli, 1998; Hacker et al., 2003), there have been no studies which quantify the continuous dehydration reactions in detail. The aim of this study is to quantify the progress of the continuous dehydration reactions of mafic rocks in the condition of greenschist facies, corresponding to low-intermediate depth (10-50km) of warm subduction zone. We use the differential thermodynamics (Spear 1993) which include mass balance to predict the continuous metamorphic reaction history of mafic rocks along the P-T trajectory of the subducting slab. With fixed bulk chemical composition the thermodynamic system is divariant, as specified in Duhem_fs theorem. In differential thermodynamics, applying a series of changes in pressure and temperature (?P and ?T, respectively) from initial conditions (P0, T0, X0s, M0s), we can trace ?Xs and ?Ms, that is, the progress (history) of the metamorphic reactions along the arbitrary P-T trajectory (Thermodynamic forward modeling). According to Okamoto and Toriumi, 2001, we modeled the greenschist/ blueschist/ (epidote -) amphibolite assemblage of mafic rocks, which consist of the following phases: Amphibole ± Epidote ± Chlorite + Plagioclase + Quartz + Fluid (H2O), in the system of Na2O - CaO - MgO - FeO - Fe2O3 - Al2O3 - SiO2 - H2O. The reference compositions and modes of minerals were assumed according to the natural sample of greenschist which has MORB-like bulk composition (Hacker et al. 2003). The reference temperature and pressure were set to be 300°C, 0.3GPa. Calculations were performed along the P-T paths of the Southwest Japan (4MPa/°C) and the Cape Mendocino (the North California, 2MPa/°C) predicted by Yamasaki and Seno, 2003. As a result, the water production rates have the peak depths at the boundary between the greenschist facies and the epidote-amphibolite facies in the Southwest Japan, and at the boundary between the greenschist facies and the amphibolite facies in the Cape Mendocino, respectively. Chlorite decomposition is the main dehydration reaction. These peak depths correspond to the zone of low frequency tremors, high Poisson_fs ratio and active seismicity (30-50km) in the Southwest Japan, and active seismicity (10-20km) in the Cape Mendocino, respectively.

  4. Onion dehydration

    SciTech Connect

    Lund, J.W.; Lienau, P.J.

    1994-07-01

    This article describes the onion dehydration process as generally practiced in the United States. The actual processing steps from harvest to final product, and geothermal applications for power production and energy requirements in the dehydration industry are discussed. A design of a dehydrator converted to geothermal energy usage is included.

  5. Toward Accurate Potentials for Condensed-Phase Chemical Reactions: Electrostatically Embedded Multi-Configuration Molecular Mechanics

    E-print Network

    Truhlar, Donald G

    Toward Accurate Potentials for Condensed-Phase Chemical Reactions: Electrostatically Embedded Multi and molecular mechanical (QM/MM) methods have provided powerful means for studying chemical reactions be used in QM/MM methods. The result is a key step toward studying chemical reactions in condensed phases

  6. Low-energy electron-induced reactions in condensed matter

    NASA Astrophysics Data System (ADS)

    Arumainayagam, Christopher R.; Lee, Hsiao-Lu; Nelson, Rachel B.; Haines, David R.; Gunawardane, Richard P.

    2010-01-01

    The goal of this review is to discuss post-irradiation analysis of low-energy (?50 eV) electron-induced processes in nanoscale thin films. Because electron-induced surface reactions in monolayer adsorbates have been extensively reviewed, we will instead focus on low-energy electron-induced reactions in multilayer adsorbates. The latter studies, involving nanoscale thin films, serve to elucidate the pivotal role that the low-energy electron-induced reactions play in high-energy radiation-induced chemical reactions in condensed matter. Although electron-stimulated desorption (ESD) experiments conducted during irradiation have yielded vital information relevant to primary or initial electron-induced processes, we wish to demonstrate in this review that analyzing the products following low-energy electron irradiation can provide new insights into radiation chemistry. This review presents studies of electron-induced reactions in nanoscale films of molecular species such as oxygen, nitrogen trifluoride, water, alkanes, alcohols, aldehydes, ketones, carboxylic acids, nitriles, halocarbons, alkane and phenyl thiols, thiophenes, ferrocene, amino acids, nucleotides, and DNA using post-irradiation techniques such as temperature-programmed desorption (TPD), reflection-absorption infrared spectroscopy (RAIRS), X-ray photoelectron spectroscopy (XPS), high-resolution electron energy loss spectroscopy (HREELS), gel electrophoresis, and microarray fluorescence. Post-irradiation temperature-programmed desorption, in particular, has been shown to be useful in identifying labile radiolysis products as demonstrated by the first identification of methoxymethanol as a reaction product of methanol radiolysis. Results of post-irradiation studies have been used not only to identify radiolysis products, but also to determine the dynamics of electron-induced reactions. For example, studies of the radiolysis yield as a function of incident electron energy have shown that dissociative electron attachment plays an important role in the electron-induced single strand breaks in DNA leading to mutagenic damage. Studies such as these not only provide insight into the fundamentals of electron-molecule interactions in the condensed phase but also may provide information valuable to (a) furthering cost-efficient destruction of hazardous chemicals, (b) understanding the electron-induced decomposition of feed gases used in the plasma processing of semiconductor devices, (c) clarifying the role, if any, of low-energy electrons, produced by cosmic rays, contributing to the formation of the ozone hole by interacting with halocarbons and producing Cl atoms, (d) illuminating the dynamics of electron-induced oligomerization and/or polymerization, and (e) explicating the astrochemistry of icy grains.

  7. The dynamics of serpentinite dehydration reactions in subduction zones: Constrains from the Cerro del Almirez ultramafic massif (Betic Cordillera, SE Spain)

    NASA Astrophysics Data System (ADS)

    Dilissen, Nicole; Garrido, Carlos J.; López Sánchez-Vizcaíno, Vicente; Padrón-Navarta, José Alberto

    2015-04-01

    Arc volcanism, earthquakes and subduction dynamics are controlled by fluids from downgoing slabs and their effect on the melting and rheology of the overlying mantle wedge. High pressure dehydration of serpentinite in the slab and the subduction channel is considered as one of the main sources of fluids in subduction zones. Even though this metamorphic reaction is essential in subduction activities, the behavior of the fluids, the kinetics and thermodynamics during the breakdown reaction are still poorly understood. The Cerro del Almirez (Nevado-Filábride Complex, Betic Cordillera, SE Spain) uniquely preserves the dehydration front from antigorite serpentinite to chlorite-harzburgite and constitutes a unique natural laboratory to investigate high-pressure dehydration of serpentinite. This reaction occurred in a subduction setting releasing up to 13 wt% of water, contributing significantly to the supply of fluids to the overlying mantle wedge. A key to the understanding of the metamorphic conditions prevailing during serpentinite dehydration is to study the two prominent textures -granofels and spinifex-like chlorite harzburgite- occurring in this reaction product. The detailed texture differences in the Chl-harzburgite can provide insights into diverse kinetic and thermodynamic conditions of this dehydration reaction due to variations in effective pressure and drainage conditions. It has been proposed that difference in overpressure (P') and deviation from growth equilibrium, i.e. overstepping, is responsible for these two types of textures [Padrón-Navarta et al., 2011]. The magnitude and duration of P' is highly dependent on dehydration kinetics [Connolly, 1997]. The fast pressure drop, with spinifex-texture as a product, can be linked to draining events expected after hydrofracturing, which are recorded in grain size reduction zones in this massif. According to this hypothesis, mapping of textural variation in Chl-harzburgite might be used as a proxy to investigate the hydrodynamics of serpentinite dehydration reaction. During an intensive detailed field mapping of a well-exposed area of ca. 0.87 km2 in the W-SW part of the massif, we mapped textural variations of Chl-harzburgite every three to ten meters. Granofels and spinifex lenses occur within scales of decimetres to decametres. These spatial scale constrains can be linked to temporal scales of the reactions and to the spatial and temporal variation of fluid release during dehydration of serpentinite. REFERENCES Connolly, J. A. D. (1997), Devolatilization-generated fluid pressure and deformation-propagated fluid flow during prograde regional metamorphism, J. Geophys. Res.-Solid Earth, 102(B8), 18149-18173, doi:10.1029/97jb00731. Padrón-Navarta, J. A., V. López Sánchez-Vizcaíno, C. J. Garrido, and M. T. Gómez-Pugnaire (2011), Metamorphic record of high-pressure dehydration of antigorite serpentinite to chlorite harzburgite in a subduction setting (Cerro del Almirez, Nevado-Filábride Complex, southern Spain), Journal of Petrology, 52(10), 2047-2078.

  8. Organic reactions catalyzed by methylrhenium trioxide: Dehydration, amination, and disproportionation of alcohols

    SciTech Connect

    Zhu, Zuolin; Espenson, J.H. [Iowa State Univ., Ames, IA (United States)] [Iowa State Univ., Ames, IA (United States)

    1996-01-12

    Methylrhenium trioxide (MTO) is the first transition metal complex in trace quantity to catalyze the direct formation of ethers from alcohols. The reactions are independent of the solvents used: benzene, toluene, dichloromethane, chloroform, acetone, and in the alcohols themselves. Aromatic alcohols gave better yields than aliphatic. Reactions between two different alcohols could also be used to prepare unsymmetric ethers, the best yields being obtained when one of the alcohols is aromatic alcohols proceeding in better yield. When primary (secondary) amines were used as the limiting reagent, direct amination of alcohols catalyzed by MTO gave good yields of the expected secondary (tertiary) amines at room temperature. Disproportionation of alcohols to alkanes and carbonyl compounds was also observed for aromatic alcohols in the presence of MTO. On the basis of the results of this investigation and a comparison with the interaction between MTO and water, a concerted process and a mechanism involving carbocation intermediates have been suggested. 5 tabs.

  9. Zeolites as catalysts in organic reactions. Claisen-Schmidt condensation of acetophenone with benzaldehyde

    Microsoft Academic Search

    M. J. Climent; H. Garcia; J. Primo; A. Corma

    1990-01-01

    HY zeolites catalyze the crossed aldol condensation of acetophenone with benzaldehyde, in benzene at 80 °C, to give trans- and cis-chalcones. Together with these expected products, 3,3-diphenylpropiophenone is also produced. In the analogous basic condensation, using phase transfer catalysis, the Michael adduct was not detected, and besides chalcone a small percentage of the Cannizzaro reaction product was observed.

  10. Clean synthesis in water. Part 2: Uncatalysed condensation reaction of Meldrum's acid and aldehydes

    Microsoft Academic Search

    Franca Bigi; Silvia Carloni; Leonetto Ferrari; Raimondo Maggi; Alessandro Mazzacani; Giovanni Sartori

    2001-01-01

    The environment-friendly condensation of Meldrum's acid and aromatic, heteroaromatic and hindered aliphatic aldehydes is performed carrying out the reaction in water at 75°C for 2 h, avoiding the addition of any catalyst.

  11. Highly-efficient synthesis of covalent porphyrinic cages via DABCO-templated imine condensation reactions.

    PubMed

    Ding, Huimin; Meng, Xiangshi; Cui, Xu; Yang, Yihui; Zhou, Tailin; Wang, Caixing; Zeller, Matthias; Wang, Cheng

    2014-10-01

    We report a new approach to construct covalent porphyrinic cages with different spacer lengths, in which the cage compounds have been conveniently synthesized in quantitative yields, via DABCO-templated imine condensation reactions. PMID:25111246

  12. An investigation of Knoevenagel condensation reaction in microreactors using a new zeolite catalyst

    Microsoft Academic Search

    Xiongfu Zhang; Emily Sau Man Lai; Rosa Martin-Aranda; King Lun Yeung

    2004-01-01

    New basic zeolite catalysts obtained by grafting amino groups onto NaX and CsNaX zeolites exhibit excellent catalytic activities for Knoevenagel condensation reaction between benzaldehyde and ethyl cyanoacetate (ECA), ethyl acetoacetate (EAA) and diethyl malonate (DEM). The CsNaX-NH2 catalyst also displays higher conversion compared to aminopropylated MCM-41. Knoevenagel condensation reaction in a CsNaX zeolite microreactor performed better than the traditional packed

  13. Dicarboxylic acid anhydride condensation with compounds containing active methylene groups. 4: Some 4-nitrophthalic anhydride condensation reactions

    NASA Technical Reports Server (NTRS)

    Oskaja, V.; Rotberg, J.

    1985-01-01

    By 4-nitrophthalic anhydride condensation with acetoacetate in acetic anhydride and triethylamine solution with subsequent breakdown of the intermediate condensation product, 5-nitroindanedione-1,3 was obtained. A 4-nitrophthalic anhydride with acetic anhydride, according to reaction conditions, may yield two products: in the presence of potassium acetate and at high temperatures 4-(or 5-)-nitro-2-acetylbenzoic acid is formed: in the presence of triethylamine and at room temperature 5-( or 6-)-nitrophthalic acetic acid is isolated. A 4-nitrophthalic anhydride and malonic acid in pyridine solution according to temperature yield either 5-( or 6-)-nitrophthalic acetic acid or 4-(or 5-)-nitro-2-acetylbenzoic acid.

  14. Condensation

    NSDL National Science Digital Library

    2012-06-26

    In this activity, learners explore the process of condensation. After seeing water vapor condense, learners will help design a test to see if cooling water vapor has an effect on the rate of condensation.

  15. Gas Phase Studies of N-Heterocyclic Carbene-Catalyzed Condensation Reactions.

    PubMed

    Tian, Yuan; Lee, Jeehiun K

    2015-07-01

    N-Heterocyclic carbenes (NHCs) catalyze Umpolung condensation reactions of carbonyl compounds, including the Stetter reaction. These types of reactions have not heretofore been examined in the gas phase. Herein, we explore the feasibility of examining these reactions in the absence of solvent. A charge-tagged thiazolylidene catalyst is used to track the reactions by mass spectrometry. We find that the first Umpolung step, the addition of the NHC catalyst to a carbonyl compound to form the "Breslow intermediate", does not readily proceed in the gas phase, contrary to the case in solution. The use of acylsilanes in place of the carbonyl compounds appears to solve this issue, presumably because of a favorable Brook rearrangement. The second addition reaction, with enones, does not occur under our gas phase conditions. These reactions do occur in solution; the differential reactivity between the condensed and gas phases is discussed, and calculations are used to aid in the interpretation of the results. PMID:26066314

  16. Alternative Interpretation of Low-Energy Nuclear Reaction Processes with Deuterated Metals Based on The Bose-Einstein Condensation Mechanism

    Microsoft Academic Search

    Yeong E. Kim; Thomas O. Passell

    Recently, a generalization of the Bose-Einstein condensation (BEC) mechanism has been made to a ground-state mixture of two different species of positively charged bosons in harmonic traps. The theory has been used to describe (D + Li) reactions in the low energy nuclear reaction (LENR) processes in condensed matter and predicts that the (D + Li) reaction rates can be

  17. Alternative Interpretation of Low-Energy Nuclear Reaction Processes with Deuterated Metals Based on the Bose-Einstein Condensation Mechanism

    Microsoft Academic Search

    Yeong E. Kim; Thomas O. Passell

    2006-01-01

    Recently, a generalization of the Bose-Einstein condensation (BEC) mechanism has been made to a ground-state mixture of two different species of positively charged bosons in harmonic traps. The theory has been used to describe (D + Li) reactions in the low energy nuclear reaction (LENR) processes in condensed matter and predicts that the (D + Li) reaction rates can be

  18. Analytical solution for transient partitioning and reaction of a condensing vapor species in a droplet

    NASA Astrophysics Data System (ADS)

    Liu, Albert Tianxiang; Zaveri, Rahul A.; Seinfeld, John H.

    2014-06-01

    We present the exact analytical solution of the transient equation of gas-phase diffusion of a condensing vapor to, and diffusion and reaction in, an aqueous droplet. Droplet-phase reaction is represented by first-order chemistry. The solution facilitates study of the dynamic nature of the vapor uptake process as a function of droplet size, Henry's law coefficient, and first-order reaction rate constant for conversion in the droplet phase.

  19. Low-energy electron-induced reactions in condensed matter

    Microsoft Academic Search

    Christopher R. Arumainayagam; Hsiao-Lu Lee; Rachel B. Nelson; David R. Haines; Richard P. Gunawardane

    2010-01-01

    The goal of this review is to discuss post-irradiation analysis of low-energy (?50 eV) electron-induced processes in nanoscale thin films. Because electron-induced surface reactions in monolayer adsorbates have been extensively reviewed, we will instead focus on low-energy electron-induced reactions in multilayer adsorbates. The latter studies, involving nanoscale thin films, serve to elucidate the pivotal role that the low-energy electron-induced reactions play

  20. Initial Reaction Steps in the Condensed-Phase Decomposition of Propellants

    SciTech Connect

    Melius, C F; Piqueras, M C

    2001-12-11

    Understanding the reaction mechanisms for the decomposition of energetic materials in the condensed phase is critical to our development of detailed kinetic models of propellant combustion. To date, the reaction mechanisms in the condensed phase have been represented by global, reactions. The detailed elementary reactions subsequent to the initial NO{sub 2} bond scissioning are not known. Using quantum chemical calculations, we have investigated the possible early steps in the decomposition of energetic materials that can occur in the condensed phase. We have used methylnitrate, methylnitramine, and nitroethane as prototypes for O-NO{sub 2}, N-NO{sub 2} and C-NO{sub 2} nitro compounds. We find the energetic radicals formed from the initial NO{sub 2} bond scissioning can be converted to unsaturated non-radical intermediates as an alternative to the unzipping of the energetic radical. We propose a new, prompt oxidation mechanism in which the trapped HONO can add back onto the energetic molecule. This produces oxidation products in the condensed phase that normally would not be produced until much later in the flame. We have shown that this prompt oxidation mechanism is a general feature of both nitramines and nitrate esters. The resulting HONO formed by the H-atom abstraction will be strongly influenced by the cage effect of the condensed phase. The applicability of this mechanism is demonstrated for decomposition of ethylnitrate, illustrating the importance of the cage effect in enabling this mechanism to occur at low temperatures.

  1. Cross-condensation reactions in an organically modified silica sol-gel

    SciTech Connect

    Prabakar, S.; Raman, N.K. [New Mexico Univ., Albuquerque, NM (United States); Assink, R.A. [Sandia National Labs., Albuquerque, NM (United States); Brinker, C.J. [New Mexico Univ., Albuquerque, NM (United States)]|[Sandia National Labs., Albuquerque, NM (United States)

    1993-12-31

    High resolution {sup 29}Si NMR has been used to study the extent of cross condensation taking place in a hybrid organic/inorganic sol-gel system. Tetraethoxysilane (TEOS) and methltriethoxysilane (MTEOS) sol-gels were chosen for this purpose. The sols were prepared by acid catalyzed hydrolysis of TEOS and MTEOS with a H{sub 2}O/Si ratio of 0.3. {sup 29}Si NMR shows signals due to both self-condensation and cross-condensation between TEOS and MTEOS. Resonance assignments were made by comparing the positions and intensities of peaks in the spectra of single and multicomponent systems. It was found that, within experimental error, the self- and cross-condensation rates are equal and that extensive molecular level mixing takes place during the early stages of the reaction.

  2. Onion dehydration

    SciTech Connect

    Lund, J.W. [Geo-Heat Center Oregon Institute of Technology, Kalamath Falls, OR (United States)

    1995-12-31

    Onion dehydration consists of a continuous operation, belt conveyor using fairly low-temperature hot air from 38-104{degrees}C (100 to 200{degrees}F). Typical processing plants will handle 4500 kg (10,000 pounds) of raw product per hour (single line), reducing the moisture from around 83 % to 4 % (680 to 820 kg - 1,500 to 1,800 pounds finished product). An example of a geothermal processing plant is Integrate Ingredients at Empire, Nevada, in the San Emidio Desert. A total of 6.3 million kg (14 million pounds) of dry product are produced annually: 60% onion and 40% garlic. A 130{degrees}C (266{degrees}F) well provide the necessary heat for the plant.

  3. Rapid and Efficient Functionalized Ionic Liquid-Catalyzed Aldol Condensation Reactions Associated with Microwave Irradiation

    PubMed Central

    Wang, Chang; Liu, Jing; Leng, Wenguang; Gao, Yanan

    2014-01-01

    Five quaternary ammonium ionic liquid (IL) and two tetrabutylphosphonium ILs were prepared and characterized. An environmentally benign and convenient functionalized ionic liquid catalytic system was thus explored in the aldol condensation reactions of aromatic aldehydes with acetone. The aldol reactions proceeded more efficiently through microwave-assisted heating than through conventional thermal heating. The yield of products obtained under microwave heating for 30 min was approximately 90%, and the ILs can be recovered and reused at least five times without apparent loss of activity. In addition, this catalytic system can be successfully extended to the Henry reactions. PMID:24445262

  4. Mixtures of Charged Bosons Confined in Harmonic Traps and Bose-Einstein Condensation Mechanism for Low-Energy Nuclear Reactions and Transmutation Processes in Condensed Matters

    NASA Astrophysics Data System (ADS)

    Kim, Yeong E.; Zubarev, Alexander L.

    2006-02-01

    A mixture of two different species of positively charged bosons in harmonic traps is considered in the mean-field approximation. It is shown that depending on the ratio of parameters, the two components may coexist in same regions of space, in spite of the Coulomb repulsion between the two species. Application of this result is discussed for the generalization of the Bose-Einstein condensation mechanism for low-energy nuclear reaction (LENR) and transmutation processes in condensed matters. For the case of deutron-lithium (d + Li) LENR, the result indicates that (d + 6Li) reactions may dominate over (d + d) reactions in LENR experiments.

  5. Rate-promoting vibrations and coupled hydrogen-electron transfer reactions in the condensed phase: A model for enzymatic catalysis

    Microsoft Academic Search

    Joshua S. Mincer; Steven D. Schwartz

    2004-01-01

    A model is presented for coupled hydrogen-electron transfer reactions in condensed phase in the presence of a rate promoting vibration. Large kinetic isotope effects (KIEs) are found when the hydrogen is substituted with deuterium. While these KIEs are essentially temperature independent, reaction rates do exhibit temperature dependence. These findings agree with recent experimental data for various enzyme-catalyzed reactions, such as

  6. Rate-promoting vibrations and coupled hydrogen–electron transfer reactions in the condensed phase: A model for enzymatic catalysis

    Microsoft Academic Search

    Joshua S. Mincer; Steven D. Schwartz

    2004-01-01

    A model is presented for coupled hydrogen–electron transfer reactions in condensed phase in the presence of a rate promoting vibration. Large kinetic isotope effects (KIEs) are found when the hydrogen is substituted with deuterium. While these KIEs are essentially temperature independent, reaction rates do exhibit temperature dependence. These findings agree with recent experimental data for various enzyme-catalyzed reactions, such as

  7. Dehydration reactions, mass transfer and rock deformation relationships during subduction of Alpine metabauxites: insights from LIBS compositional profiles between metamorphic veins

    NASA Astrophysics Data System (ADS)

    Verlaguet, Anne; Brunet, Fabrice; Goffé, Bruno; Menut, Denis; Findling, Nathaniel; Poinssot, Christophe

    2013-04-01

    In subduction zones, the significant amounts of aqueous fluid released in the course of the successive dehydration reactions occurring during prograde metamorphism are expected to strongly influence the rock rheology, as well as kinetics of metamorphic reactions and mass transfer efficiency. Mineralized veins, ubiquitous in metamorphic rocks, can be seen as preserved witnesses of fluid and mass redistribution that partly accommodate the rock deformation (lateral segregation). However, the driving forces and mechanisms of mass transfer towards fluid-filled open spaces remain somewhat unclear. The aim of this study is to investigate the vein-forming processes and the modalities of mass transfer during local fluid-rock interactions, and their links with fluid production and rock deformation, with new insights from Laser Induced Breakdown Spectroscopy (LIBS) profiles. This study focuses on karstic pockets (metre scale) of Triassic metabauxites embedded in thick carbonate units, that have been isolated from large-scale fluid flow during HP-LT Alpine metamorphism (W. Vanoise, French Alps). These rocks display several generations of metamorphic veins containing various Al-bearing minerals, which give particular insights into mass transfer processes. It is proposed that the internally-derived fluid (~13 vol% produced by successive dehydration reactions) has promoted the opening of fluid-filled open spaces (euhedral habits of vein minerals) and served as medium for diffusive mass transfer from rock to vein. Based on mineralogical and textural features, two vein types can be distinguished: (1) some veins are filled with newly formed products of either prograde (chloritoid) or retrograde (chlorite) metamorphic reactions; in this case, fluid-filled open spaces seem to offer energetically favourable nucleation/growth sites; (2) the second vein type is filled with cookeite (Li-Al-rich chlorite) or pyrophyllite, that were present in the host rock prior to the vein formation. In this closed chemical system, mass transfer from rock to vein was achieved through the fluid, in a dissolution-transport-precipitation process, possibly stress-assisted. To investigate the modalities of mass transfer towards this second vein type, LIBS profiles were performed in the rock matrix, taking Li concentration as a proxy for cookeite distribution. Cookeite is highly concentrated (40-70 vol%) in regularly spaced veins, and the LIBS profiles show that cookeite is evenly distributed in the rock matrix comprised between two veins. The absence of diffusion profiles suggests that the characteristic diffusion length for Li, Al and Si is greater than or equal to the distance separating two cookeite veins (3-6 cm). This is in agreement with characteristic diffusion lengths calculated from both grain boundary and pore fluid diffusion coefficients, for the estimated duration of the peak of metamorphism. Concerning mass transfer driving forces, phyllosilicates have very different morphologies in the rock matrix (fibers) compared to veins (euhedral crystals): fluid-mineral interfacial energy may be maximal in the small matrix pores, which can maintain higher cookeite solubility than in fluid-filled open spaces. Therefore, as soon as veins open, chemical potential gradients may develop and drive cookeite transfer from rock matrix to veins.

  8. Dehydration reactions, mass transfer and rock deformation relationships during subduction of Alpine metabauxites: insights from LIBS compositional profiles between metamorphic veins

    NASA Astrophysics Data System (ADS)

    Verlaguet, A.; Brunet, F.; Goffe, B.; Menut, D.; Findling, N.; Poinssot, C.

    2011-12-01

    In subduction zones, the significant amounts of aqueous fluid released in the course of the successive dehydration reactions occurring during prograde metamorphism are expected to strongly influence the rock rheology, as well as kinetics of metamorphic reactions and mass transfer efficiency. Mineralized veins, ubiquitous in metamorphic rocks, can be seen as preserved witnesses of fluid and mass redistribution that partly accommodate the rock deformation (lateral segregation). However, the driving forces and mechanisms of mass transfer towards fluid-filled open spaces remain somewhat unclear. The aim of this study is to investigate the modalities of mass transfer during local fluid-rock interactions, and their links with fluid production and rock deformation. This study focuses on karstic pockets (metre scale) of Triassic metabauxites embedded in thick carbonate units, that have been isolated from large-scale fluid flow during HP-LT Alpine metamorphism (W. Vanoise, French Alps). These rocks display several generations of metamorphic veins containing various Al-bearing minerals, which give particular insights into mass transfer processes. It is proposed that the internally-derived fluid (~13 vol% produced by successive dehydration reactions) has promoted the opening of fluid-filled open spaces (euhedral habits of vein minerals) and served as medium for diffusive mass transfer from rock to vein. Based on mineralogical and textural features, two vein types can be distinguished: (1) some veins are filled with newly formed products of either prograde (chloritoid) or retrograde (chlorite) metamorphic reactions; in this case, fluid-filled open spaces seem to offer energetically favourable nucleation/growth sites; (2) the second vein type is filled with cookeite (Li-Al-rich chlorite) or pyrophyllite, that were present in the host rock prior to the vein formation. In this closed chemical system, mass transfer from rock to vein was achieved through the fluid, in a dissolution-transport-precipitation process, possibly stress-assisted. Cookeite is highly concentrated (40-70 vol%) in regularly spaced veins. Laser Induced Breakdown Spectroscopy profiles show that cookeite is evenly distributed in the rock matrix comprised between two veins. The absence of diffusion profiles suggests that the characteristic diffusion length for Li, Al and Si is greater than or equal to the distance separating two cookeite veins (3-6 cm). This is in agreement with characteristic diffusion lengths calculated from both grain boundary and pore fluid diffusion coefficients, for the estimated duration of the peak of metamorphism. Phyllosilicates have very different morphologies in the rock matrix (fibers) compared to veins (euhedral crystals): fluid-mineral interfacial energy may be maximal in the small matrix pores, which can maintain higher cookeite solubility than in fluid-filled open spaces. Therefore, as soon as veins open, chemical potential gradients may develop and drive cookeite transfer from rock matrix to veins.

  9. Slab dehydration and fluid-producing metamorphic reactions in early subduction stages: the record of the metamorphic sole of the Mont Albert ophiolite (Quebec, Canada)

    NASA Astrophysics Data System (ADS)

    Jewison, Ella; Soret, Mathieu; Dubacq, Benoït; Agard, Philippe; Labrousse, Loïc

    2015-04-01

    Metamorphic soles found at the base of obducted ophiolites provide valuable information on the early history of the subduction / obduction system. Metamorphic soles are characterised by rocks originating from the ocean floor (basalts and sediments in variable proportions) metamorphosed up to granulite facies, where the intensity of metamorphism increases to the top of the unit, towards the contact with peridotite. Their mafic and less frequently pelitic lithologies make them sensitive recorders of their pressure-temperature conditions of crystallization and allow radiometric dating. In addition, metamorphic soles have directly witnessed slab dehydration as they underwent similar fluid-producing metamorphic reactions before being accreted to the mantle wedge peridotites (i.e. before "underplating"). The mechanisms of underplating remain uncertain, because of the somewhat obscure link between weakening through fluid production and hardening via garnet crystallization, with direct consequences on the rheology of the plate interface. In this study, we document fluid-producing reactions occurring during the prograde history of the metamorphic sole of the Taconian (ca. 460 Ma) ophiolite from Mont Albert (Quebec, Canada). This metamorphic sole shows variably metamorphosed mafic and pelitic rocks with metamorphic gradients over the scale of 10 metres, with clinopyroxene-garnet-amphibole granulite facies mafic rocks at the contact with the overlying peridotites. Evidences of melting of pelitic lithologies increase towards the contact, and no remains of metapelites have been found within about 20 m from the contact. Fluid channelization and melt migration is evidenced by decimetric dykes and veins. Away from the contact, metamorphism intensity gradually decreases to greenschist facies with abundant hydrated silicates. The aim of the study is to provide constraints (i) on the nature of the fluids produced (aqueous versus melt), (ii) on their composition and (iii) on the pressure-temperature conditions of their production. This will allow a better understanding of the rheological behaviour of subducting slabs in subduction zones and of amphibolites in the lower continental crust.

  10. The base catalyzed hydrolysis and condensation reactions of dilute and concentrated TEOS (Tetraethylorthosilicate) solutions: Draft

    SciTech Connect

    Harris, M.T.; Byers, C.H.; Brunson, R.R.

    1989-01-01

    The synthesis of submicron silica particles by the hydrolysis and condensation of dilute and concentrated solutions of tetraethylorthosiliate (TEOS) has been studied in low-molecular weight alcohols (C/sub 1/--C/sub 4/). A base (ammonia) is used to catalyze the reaction. Raman spectroscopy, gas chromatography and the molybdate method are used to establish the hydrolysis and condensation kinetics. Dynamic and classical light-scattering techniques are employed to monitor particle growth and particle number concentration kinetics, and particle size distribution. The effects of solvent and TEOS concentration on the degree of monodispersity of the particles will be discussed. Furthermore, the chemical and particle growth data will be used to test the theories of homogeneous nucleation and coagulative nucleation, which have been proposed as the mechanisms that govern the growth of submicron monodisperse silica particle by TEOS hydrolysis. 13 refs., 4 figs., 1 tab.

  11. Validated spectrofluorimetric method for determination of sulpiride in commercial formulations using Hantzsch condensation reaction.

    PubMed

    Shah, Jasmin; Jan, Muhammad Rasul; Khan, Muhammad Naeem; Shah, Sultan

    2013-09-01

    A simple, sensitive, selective and cost effective spectrofluorimetric method has been established for the quantification of sulpiride after their complete alkaline hydrolysis. The method is based on the condensation of the primary amino group of alkaline hydrolytic product of sulpiride with acetyl acetone and formaldehyde in acidic medium (0.25 M HCl) to form a fluorescent product. The reaction product formed shows maximum fluorescence intensity at 483 nm after excitation at 431 nm. The different reaction conditions influencing the condensation reaction were carefully optimized and a linear range of 0.1-3.5 µg mL-1 with good correlation coefficient between flourescent intensity and concentration of sulpiride was found at optimum parameters. The LOD and LOQ were found to be 11 and 39 ng mL-1 respectively. The proposed method was successfully used for the quantification of sulpiride in bulk powder and commercial formulations. The effect of common pharmaceutical excipients and co-administered drug was also studied and no interferences were observed. The validity of the method was tested by analyzing sulpiride in bulk powder, and pharmaceutical formulations through recovery studies. Recoveries (%) were obtained from 98.62 to 100.24% for bulk powder, and 97.09 to 100.57 % for commercial formulations. The results were validated statistically with those obtained by reference literature high performance liquid chromatographic method. PMID:24035947

  12. 2112 J. Am. Chem. SOC.1995,117, 2112-2113 Reactions of Ethoxysilaneswith Silica: A

    E-print Network

    Bluemel, Janet

    ~graphy,'.~-*because they provide strong bonding via up to three siloxane groups and high surface coverage without acidic reaction spectroscopy that ethoxysi- lane reagents react directly with siloxane bonds of dehydrated silica. 29Siand I3 three siloxane bonds upon condensation reaction with silica surface silanol groups: there always exists

  13. Quantum and Molecular Mechanical (QM/MM) Monte Carlo Techniques for Modeling Condensed-Phase Reactions.

    PubMed

    Acevedo, Orlando; Jorgensen, Wiliiam L

    2014-09-01

    A recent review (Acc. Chem. Res. 2010, 43:142-151) examined our use and development of a combined quantum and molecular mechanical (QM/MM) technique for modelling organic and enzymatic reactions. Advances included the PDDG/PM3 semiempirical QM (SQM) method, computation of multi-dimensional potentials of mean force (PMF), incorporation of on-the-fly QM in Monte Carlo simulations, and a polynomial quadrature method for rapidly treating proton-transfer reactions. The current article serves as a follow up on our progress. Highlights include new reactions, alternative SQM methods, a polarizable OPLS force field, and novel solvent environments, e.g., "on water" and room temperature ionic liquids. The methodology is strikingly accurate across a wide range of condensed-phase and antibody-catalyzed reactions including substitution, decarboxylation, elimination, isomerization, and pericyclic classes. Comparisons are made to systems treated with continuum-based solvents and ab initio or density functional theory (DFT) methods. Overall, the QM/MM methodology provides detailed characterization of reaction paths, proper configurational sampling, several advantages over implicit solvent models, and a reasonable computational cost. PMID:25431625

  14. Alternative Interpretation of Low-Energy Nuclear Reaction Processes with Deuterated Metals Based on the Bose-Einstein Condensation Mechanism

    NASA Astrophysics Data System (ADS)

    Kim, Yeong E.; Passell, Thomas O.

    2006-02-01

    Recently, a generalization of the Bose-Einstein condensation (BEC) mechanism has been made to a ground-state mixture of two different species of positively charged bosons in harmonic traps. The theory has been used to describe (D + Li) reactions in the low energy nuclear reaction (LENR) processes in condensed matter and predicts that the (D + Li) reaction rates can be larger than (D + D) reaction rates by as much as a factor of ~50, implying that (D + Li) reactions may be occuring in addition to the (D + D) reactions. A survey of the existing data from LENR experiments is carried out to check the validity of the theoretical prediction. We conclude that there is compelling experimental evidence which support the theoretical prediction. New experimental tests of the theoretical prediction are suggested.

  15. Technical Note: Analytical Solution for Transient Partitioning and Reaction of a Condensing Vapor Species in a Droplet

    SciTech Connect

    Liu, Albert T.; Zaveri, Rahul A.; Seinfeld, John H.

    2014-03-28

    We present the exact analytical solution of the transient equation of gas-phase diffusion of a condensing vapor to, and diffusion and reaction in, an aqueous droplet. Droplet-phase reaction is represented by first-order chemistry. The solution facilitates study of the dynamic nature of the vapor uptake process as a function of droplet size, Henry’s law coefficient, and first-order reaction rate constant for conversion in the droplet phase.

  16. Closure of the condensed-phase organic-nitrate reaction USQ at hanford

    SciTech Connect

    COWLEY, W.L.

    1999-06-24

    A discovery Unreviewed Safety Question (USQ) was declared on the underground waste storage tanks at the Hanford Site in May 1996. The USQ was for condensed-phase organic-nitrate reactions (sometimes called organic complexant reactions) in the tanks. This paper outlines the steps taken to close the USQ, and resolve the related safety issue. Several processes were used at the Hanford Site to extract and/or process plutonium. These processes resulted in organic complexants (for chelating multivalent cations) and organic extraction solvents being sent to the underground waste storage tanks. This paper addresses the organic complexant hazard. The organic complexants are in waste matrices that include inert material, diluents, and potential oxidizers. In the presence of oxidizing material, the complexant salts can be made to react exothermically by heating to high temperatures or by applying an external ignition source of sufficient energy. The first organic complexant hazard assessments focused on determining whether a hulk runaway reaction could occur, similar to the 1957 accident at Kyshtm (a reprocessing plant in the former U.S.S.R.). Early analyses (1977 through 1994) examined organic-nitrate reaction onset temperatures and concluded that a bulk runaway reaction could not occur at the Hanford Site because tank temperatures were well below that necessary for bulk runaway. Therefore, it was believed that organic-nitrate reactions were adequately described in the then current Authorization Basis (AB). Subsequent studies examined a different accident scenario, propagation resulting from an external ignition source (e.g., lightning or welding slag) that initiates a combustion front that propagates through the organic waste. A USQ evaluation determined that localized high energy ignition sources were credible, and that point source ignition of organic complexant waste was not adequately addressed i n the then existing AB. Consequently, the USQ was declared on the underground storage tanks in May 1996 for condensed-phase organic-nitrate reactions. At the same time that the operating contractor recommended that the U. S. Department of Energy (DOE) declare a USQ. preventative coiitrols were implemented to minimize potential ignition sources and prevent a possible accident.

  17. Hydrous mineral dehydration around heat-generating nuclear waste in bedded salt formations.

    PubMed

    Jordan, Amy B; Boukhalfa, Hakim; Caporuscio, Florie A; Robinson, Bruce A; Stauffer, Philip H

    2015-06-01

    Heat-generating nuclear waste disposal in bedded salt during the first two years after waste emplacement is explored using numerical simulations tied to experiments of hydrous mineral dehydration. Heating impure salt samples to temperatures of 265 °C can release over 20% by mass of hydrous minerals as water. Three steps in a series of dehydration reactions are measured (65, 110, and 265 °C), and water loss associated with each step is averaged from experimental data into a water source model. Simulations using this dehydration model are used to predict temperature, moisture, and porosity after heating by 750-W waste canisters, assuming hydrous mineral mass fractions from 0 to 10%. The formation of a three-phase heat pipe (with counter-circulation of vapor and brine) occurs as water vapor is driven away from the heat source, condenses, and flows back toward the heat source, leading to changes in porosity, permeability, temperature, saturation, and thermal conductivity of the backfill salt surrounding the waste canisters. Heat pipe formation depends on temperature, moisture availability, and mobility. In certain cases, dehydration of hydrous minerals provides sufficient extra moisture to push the system into a sustained heat pipe, where simulations neglecting this process do not. PMID:25965632

  18. Dehydration, Dehydrogenation, and Condensation of Alcohols on Supported Oxide Catalysts Based on Cyclic (WO3)3 and (MoO3)3 Clusters

    SciTech Connect

    Rousseau, Roger J.; Dixon, David A.; Kay, Bruce D.; Dohnalek, Zdenek

    2014-01-01

    Supported early transition metal oxides have important applications in numerous catalytic reactions. In this article we review preparation and activity of well-defined model WO3 and MoO3 catalysts prepared via deposition of cyclic gas-phase (WO3)3 and (MoO3)3 clusters generated by sublimation of WO3 and MoO3 powders. Conversion of small aliphatic alcohols to alkenes, aldehydes/ketons, and ethers is employed to probe the structure-activity relationships on model WO3 and MoO3 catalysts ranging from unsupported (WO3)3 and (MoO3)3 clusters embedded in alcohol matrices, to (WO3)3 clusters supported on surfaces of other oxides, and epitaxial and nanoporous WO3 films. Detailed theoretical calculations reveal the underlying reaction mechanisms and provide insight into the origin of the differences in the WO3 and MoO3 reactivity. For the range of interrogated (WO3)3 they further shed light into the role structure and binding of (WO3)3 clusters with the support play in determining their catalytic activity.

  19. Thirst, Drinking Behavior, And Dehydration

    NASA Technical Reports Server (NTRS)

    Greenleaf, John

    1996-01-01

    Report describes review of physiological mechanisms of involuntary dehydration. Researchers considered cellular dehydration and effects of sodium on thirst, as well as extracellular dehydration and restoration of vascular volume, effects of renin on thirst, and effects of heat.

  20. Progress toward chemical accuracy in the computer simulation of condensed phase reactions.

    PubMed Central

    Bash, P A; Ho, L L; MacKerell, A D; Levine, D; Hallstrom, P

    1996-01-01

    We describe a procedure for the generation of chemically accurate computer-simulation models to study chemical reactions in the condensed phase. The process involves (i) the use of a coupled semiempirical quantum and classical molecular mechanics method to represent solutes and solvent, respectively; (ii) the optimization of semiempirical quantum mechanics (QM) parameters to produce a computationally efficient and chemically accurate QM model; (iii) the calibration of a quantum/classical microsolvation model using ab initio quantum theory; and (iv) the use of statistical mechanical principles and methods to simulate, on massively parallel computers, the thermodynamic properties of chemical reactions in aqueous solution. The utility of this process is demonstrated by the calculation of the enthalpy of reaction in vacuum and free energy change in aqueous solution for a proton transfer involving methanol, methoxide, imidazole, and imidazolium, which are functional groups involved with proton transfers in many biochemical systems. An optimized semiempirical QM model is produced, which results in the calculation of heats of formation of the above chemical species to within 1.0 kcal/mol (1 kcal = 4.18 kJ) of experimental values. The use of the calibrated QM and microsolvation QM/MM (molecular mechanics) models for the simulation of a proton transfer in aqueous solution gives a calculated free energy that is within 1.0 kcal/mol (12.2 calculated vs. 12.8 experimental) of a value estimated from experimental pKa values of the reacting species. PMID:11607654

  1. Progress toward chemcial accuracy in the computer simulation of condensed phase reactions

    SciTech Connect

    Bash, P.A.; Levine, D.; Hallstrom, P. [Argonne National Lab., IL (United States); Ho, L.L. [Yale Univ., New Haven, CT (United States). Dept. of Physics; Mackerell, A.D. Jr. [Univ. of Maryland, Baltimore, MD (United States). Dept. of Pharmaceutical Sciences

    1996-03-01

    A procedure is described for the generation of chemically accurate computer-simulation models to study chemical reactions in the condensed phase. The process involves (1) the use of a coupled semiempirical quantum and classical molecular mechanics method to represent solutes and solvent, respectively; (2) the optimization of semiempirical quantum mechanics (QM) parameters to produce a computationally efficient and chemically accurate QM model; (3) the calibration of a quantum/classical microsolvation model using ab initio quantum theory; and (4) the use of statistical mechanical principles and methods to simulate, on massively parallel computers, the thermodynamic properties of chemical reactions in aqueous solution. The utility of this process is demonstrated by the calculation of the enthalpy of reaction in vacuum and free energy change in aqueous solution for a proton transfer involving methanol, methoxide, imidazole, and imidazolium, which are functional groups involved with proton transfers in many biochemical systems. An optimized semiempirical QM model is produced, which results in the calculation of heats of formation of the above chemical species to within 1.0 kcal/mol of experimental values. The use of the calibrated QM and microsolvation QM/MM models for the simulation of a proton transfer in aqueous solution gives a calculated free energy that is within 1.0 kcal/mol (12.2 calculated vs. 12.8 experimental) of a value estimated from experimental pKa`s of the reacting species.

  2. OSMOTIC DEHYDRATION OF PINEAPPLE

    Microsoft Academic Search

    D. Saputra

    2001-01-01

    The effects of sugar type, sugar concentration, immersion time and temperature on the mass transfer of osmotic dehydration were studied using pie shape slices (7 mm thick with its center cork thrown away) of fresh pineapple (Queen variety, 90% maturity). The dehydration process was performed using two type of sugar as an osmotic agent (glucose and sucrose), three levels of

  3. Condensation reaction between carbohydrazide and salicylaldehyde: in-line vibrational spectroscopy monitoring and characterization of the reaction products in solution and solid state.

    PubMed

    Jedna?ak, Tomislav; Novak, Predrag; Hodzic, Aden; Scheibelhofer, Otto; Khinast, Johannes G; Plavec, Janez; Sket, Primož; Parlov, Vukovi? Jelena

    2014-01-01

    The condensation reaction between carbohydrazide and salicylaldehyde was monitored in-line by using vibrational NIR and Raman spectroscopies and statistical methods. Prior to in-line data analysis the reaction products were fully characterized in solution and solid state in order to check the potential of the in-line approach as a tool for in-process Schiff bases reaction control. It was demonstrated that a combination of vibrational spectroscopy and principal component analysis made it possible to detect and identify the reaction products, e.g. mono(salicylidene)carbohydrazide (1) and bis(salicylidene)carbohydrazide (2) in different solvents, and to determine the reaction end points in real time. Owing to complexity of the reaction mixtures and band overlapping, it was not possible to determine the relative ratio of the reaction products in-line. The off-line analysis showed that 1 was predominant in methanol while the highest portion of 2 was obtained in ethanol. PMID:24664340

  4. Trialkylphosphine-stabilized copper-phenyltellurolate complexes: from small molecules to nanoclusters via condensation reactions.

    PubMed

    DeGroot, M W; Cockburn, M W; Workentin, M S; Corrigan, J F

    2001-08-27

    Reactions of CuCl with Te(Ph)SiMe3 and solublizing trialkylphosphine ligands afford a series of polynuclear copper-phenyltellurolate complexes that has been structurally characterized. The formation of the complexes is found to be highly dependent on the ancillary phosphine ligand used. The synthesis and structures of [Cu2(mu-TePh)2(PMe3)4] 1, [Cu4(mu3-TePh)4(PPr(i)3)3] 2, [Cu5(mu-TePh)3(mu3-TePh)3(PEt3)3][PEt3Ph] 3, and [Cu12Te3(mu3-TePh)6(PEt3)6] 4 are described. The telluride (Te(2-)) ligands in 4 arise from the generation of TePh2 in the reaction mixtures. The subsequent co-condensation of clusters 3 and 4 leads to the generation of the nanometer sized complex [Cu29Te9(mu3-TePh)10(mu4-TePh)2(PEt3)8][PEt3Ph] 5 in good yield, in addition to small amounts of [Cu39(mu3-TePh)10(mu4-TePh)Te16(PEt3)13] 6. These complexes are formed via the photo elimination of TePh2. The cyclic voltammogram of 5 in THF solution exhibits two oxidation waves, assigned to the oxidation of the Cu(I) centers. PMID:11511215

  5. Dehydration (For Parents)

    MedlinePLUS

    ... yellow urine) dry, cool skin lethargy or irritability fatigue or dizziness in an older child Preventing Dehydration ... often during hot weather. Those who participate in sports or strenuous activities should drink some extra fluid ...

  6. Fe3O4@MOF core-shell magnetic microspheres as excellent catalysts for the Claisen-Schmidt condensation reaction

    NASA Astrophysics Data System (ADS)

    Ke, Fei; Qiu, Ling-Guang; Zhu, Junfa

    2014-01-01

    Separation and recycling of catalysts after catalytic reactions are critically required to reduce the cost of catalysts as well as to avoid the generation of waste in industrial applications. In this work, we present a facile fabrication and characterization of a novel type of MOF-based porous catalyst, namely, Fe3O4@MIL-100(Fe) core-shell magnetic microspheres. It has been shown that these catalysts not only exhibit high catalytic activities for the Claisen-Schmidt condensation reactions under environmentally friendly conditions, but remarkably, they can be easily separated and recycled without significant loss of catalytic efficiency after being used for many times. Therefore, compared to other reported catalysts used in the Claisen-Schmidt condensation reactions, these catalysts are green, cheap and more suitable for large scale industrial applications.Separation and recycling of catalysts after catalytic reactions are critically required to reduce the cost of catalysts as well as to avoid the generation of waste in industrial applications. In this work, we present a facile fabrication and characterization of a novel type of MOF-based porous catalyst, namely, Fe3O4@MIL-100(Fe) core-shell magnetic microspheres. It has been shown that these catalysts not only exhibit high catalytic activities for the Claisen-Schmidt condensation reactions under environmentally friendly conditions, but remarkably, they can be easily separated and recycled without significant loss of catalytic efficiency after being used for many times. Therefore, compared to other reported catalysts used in the Claisen-Schmidt condensation reactions, these catalysts are green, cheap and more suitable for large scale industrial applications. Electronic supplementary information (ESI) available: SEM and TEM images, and GC-MS spectra for chalcones. See DOI: 10.1039/c3nr05051c

  7. Golden rule kinetics of transfer reactions in condensed phase: The microscopic model of electron transfer reactions in disordered solid matrices

    NASA Astrophysics Data System (ADS)

    Basilevsky, M. V.; Odinokov, A. V.; Titov, S. V.; Mitina, E. A.

    2013-12-01

    The algorithm for a theoretical calculation of transfer reaction rates for light quantum particles (i.e., the electron and H-atom transfers) in non-polar solid matrices is formulated and justified. The mechanism postulated involves a local mode (an either intra- or inter-molecular one) serving as a mediator which accomplishes the energy exchange between the reacting high-frequency quantum mode and the phonon modes belonging to the environment. This approach uses as a background the Fermi golden rule beyond the usually applied spin-boson approximation. The dynamical treatment rests on the one-dimensional version of the standard quantum relaxation equation for the reduced density matrix, which describes the frequency fluctuation spectrum for the local mode under consideration. The temperature dependence of a reaction rate is controlled by the dimensionless parameter ?0 = ??0/kBT where ?0 is the frequency of the local mode and T is the temperature. The realization of the computational scheme is different for the high/intermediate (?0 < 1 - 3) and for low (?0 ? 1) temperature ranges. For the first (quasi-classical) kinetic regime, the Redfield approximation to the solution of the relaxation equation proved to be sufficient and efficient in practical applications. The study of the essentially quantum-mechanical low-temperature kinetic regime in its asymptotic limit requires the implementation of the exact relaxation equation. The coherent mechanism providing a non-vanishing reaction rate has been revealed when T ? 0. An accurate computational methodology for the cross-over kinetic regime needs a further elaboration. The original model of the hopping mechanism for electronic conduction in photosensitive organic materials is considered, based on the above techniques. The electron transfer (ET) in active centers of such systems proceeds via local intra- and intermolecular modes. The active modes, as a rule, operate beyond the kinetic regimes, which are usually postulated in the existing theories of the ET. Our alternative dynamic ET model for local modes immersed in the continuum harmonic medium is formulated for both classical and quantum regimes, and accounts explicitly for the mode/medium interaction. The kinetics of the energy exchange between the local ET subsystem and the surrounding environment essentially determine the total ET rate. The efficient computer code for rate computations is elaborated on. The computations are available for a wide range of system parameters, such as the temperature, external field, local mode frequency, and characteristics of mode/medium interaction. The relation of the present approach to the Marcus ET theory and to the quantum-statistical reaction rate theory [V. G. Levich and R. R. Dogonadze, Dokl. Akad. Nauk SSSR, Ser. Fiz. Khim. 124, 213 (1959); J. Ulstrup, Charge Transfer in Condensed Media (Springer, Berlin, 1979); M. Bixon and J. Jortner, Adv. Chem. Phys. 106, 35 (1999)] underlying it is discussed and illustrated by the results of computations for practically important target systems.

  8. Golden rule kinetics of transfer reactions in condensed phase: The microscopic model of electron transfer reactions in disordered solid matrices

    SciTech Connect

    Basilevsky, M. V.; Mitina, E. A. [Photochemistry Center, Russian Academy of Sciences, 7a, Novatorov ul., Moscow (Russian Federation)] [Photochemistry Center, Russian Academy of Sciences, 7a, Novatorov ul., Moscow (Russian Federation); Odinokov, A. V. [Photochemistry Center, Russian Academy of Sciences, 7a, Novatorov ul., Moscow (Russian Federation) [Photochemistry Center, Russian Academy of Sciences, 7a, Novatorov ul., Moscow (Russian Federation); National Research Nuclear University “MEPhI,” 31, Kashirskoye shosse, Moscow (Russian Federation); Titov, S. V. [Karpov Institute of Physical Chemistry, 3-1/12, Building 6, Obuha pereulok, Moscow (Russian Federation)] [Karpov Institute of Physical Chemistry, 3-1/12, Building 6, Obuha pereulok, Moscow (Russian Federation)

    2013-12-21

    The algorithm for a theoretical calculation of transfer reaction rates for light quantum particles (i.e., the electron and H-atom transfers) in non-polar solid matrices is formulated and justified. The mechanism postulated involves a local mode (an either intra- or inter-molecular one) serving as a mediator which accomplishes the energy exchange between the reacting high-frequency quantum mode and the phonon modes belonging to the environment. This approach uses as a background the Fermi golden rule beyond the usually applied spin-boson approximation. The dynamical treatment rests on the one-dimensional version of the standard quantum relaxation equation for the reduced density matrix, which describes the frequency fluctuation spectrum for the local mode under consideration. The temperature dependence of a reaction rate is controlled by the dimensionless parameter ?{sub 0}=??{sub 0}/k{sub B}T where ?{sub 0} is the frequency of the local mode and T is the temperature. The realization of the computational scheme is different for the high/intermediate (?{sub 0} < 1 ? 3) and for low (?{sub 0}? 1) temperature ranges. For the first (quasi-classical) kinetic regime, the Redfield approximation to the solution of the relaxation equation proved to be sufficient and efficient in practical applications. The study of the essentially quantum-mechanical low-temperature kinetic regime in its asymptotic limit requires the implementation of the exact relaxation equation. The coherent mechanism providing a non-vanishing reaction rate has been revealed when T? 0. An accurate computational methodology for the cross-over kinetic regime needs a further elaboration. The original model of the hopping mechanism for electronic conduction in photosensitive organic materials is considered, based on the above techniques. The electron transfer (ET) in active centers of such systems proceeds via local intra- and intermolecular modes. The active modes, as a rule, operate beyond the kinetic regimes, which are usually postulated in the existing theories of the ET. Our alternative dynamic ET model for local modes immersed in the continuum harmonic medium is formulated for both classical and quantum regimes, and accounts explicitly for the mode/medium interaction. The kinetics of the energy exchange between the local ET subsystem and the surrounding environment essentially determine the total ET rate. The efficient computer code for rate computations is elaborated on. The computations are available for a wide range of system parameters, such as the temperature, external field, local mode frequency, and characteristics of mode/medium interaction. The relation of the present approach to the Marcus ET theory and to the quantum-statistical reaction rate theory [V. G. Levich and R. R. Dogonadze, Dokl. Akad. Nauk SSSR, Ser. Fiz. Khim. 124, 213 (1959); J. Ulstrup, Charge Transfer in Condensed Media (Springer, Berlin, 1979); M. Bixon and J. Jortner, Adv. Chem. Phys. 106, 35 (1999)] underlying it is discussed and illustrated by the results of computations for practically important target systems.

  9. Intramolecular condensation reactions of {alpha}, {omega}- bis(triethoxy-silyl)alkanes. Formation of cyclic disilsesquioxanes

    SciTech Connect

    Loy, D.A.; Carpenter, J.P.; Myers, S.A.; Assink, R.A.; Small, J.H. [Sandia National Labs., Albuquerque, NM (United States); Greaves, J.; Shea, K.J. [California Univ., Irvine, CA (United States). Dept. of Chemistry

    1996-08-01

    Under acidic sol-gel polymerization conditions, 1,3-bis(triethoxysilyl)-propane (1) and 1,4-bis(triethoxysilyl)butane (2) were shown to preferentially form cyclic disilsesquioxanes 3 and 4 rather than the expected 1,3-propylene- and 1,4-butylene-bridged polysilsesquioxane gels. Formation of 3 and 4 is driven by a combination of an intramolecular cyclization to six and seven membered rings, and a pronounced reduction in reactivity under acidic conditions as a function of increasing degree of condensation. The ease with which these relatively unreactive cyclic monomers and dimers are formed (under acidic conditions) helps to explain the difficulties in forming gels from 1 and 2. The stability of cyclic disilsesquioxanes was confirmed withe the synthesis of 3 and 4 in gram quantities; the cyclic disilsesquioxanes react slowly to give tricyclic dimers containing a thermodynamically stable eight membered siloxane ring. Continued reactions were shown to perserve the cyclic structure, opening up the possibility of utilizing cyclic disilsesquioxanes as sol-gel monomers. Preliminary polymerization studies with these new, carbohydrate-like monomers revealed the formation of network poly(cyclic disilsesquioxanes) under acidic conditions and polymerization with ring-opening under basic conditions.

  10. Plastic and dehydration instabilities of antigorite serpentinite

    NASA Astrophysics Data System (ADS)

    Ando, J.; Katayama, I.; Ohfuji, H.; Terada, Y.

    2008-12-01

    We conducted a constant displacement rate test of antigorite serpentinite by a triaxial solid medium deformation apparatus installed at Hiroshima University. Experimental conditions were P = ca. 1.0 GPa, T = 450 C to 800 C, which cover from stability to dehydration conditions of antigorite, and strain rate of digit of 10-5 /sec. Samples were cylindrical shape cored from serpentinite and their sizes were 7 mm x 7 mm and 5 mm x 5 mm in diameter by length. Faults were observed in recovered samples from all temperature conditions. Mechanical data of faulted samples showed stress drop of several 10 MPa during experiments. The followings summarize microstructural observations of the recovered samples, and propose generation processes of fault at stability and dehydration conditions. 1) Stability field (plastic instability): Antigorite grains develop a lattice preferred orientation (LPO) along a fault, which characterized by (001) cleavage face parallel to fault plane. This fact suggests the fault is generated by the following process. i) Antigorite grains on the plane applied by maximum shear stress are preferentially deformed by plastic manner, and then develop the LPO. ii) The arrangement of cleavage face gradually reduces the strength of this plane. iii) Eventually, embrittlement occurs at the critical point when the rock strength along this weak plane becomes smaller than shear stress. 2) Dehydration condition (dehydration instability): Fine grained dehydration phases less than 1 micrometer in size such as olivine and talc are detected as a thin vein along the fault. Moreover, talc and olivine, or antigorite ca. 1 - 5 micrometers in size with angular shape are observed within the fault as a fault gauge. These facts suggest the following generation process of fault. i) Dehydration reaction of antigorite begins on the plane applied by maximum shear stress and expands along this plane. ii) The dehydration gradually reduces the strength of this plane. iii) Eventually, embrittlement occurs at the critical point when the rock strength along this weak plane becomes smaller than shear stress.

  11. Catalytic performance of Metal-Organic-Frameworks vs. extra-large pore zeolite UTL in condensation reactions

    NASA Astrophysics Data System (ADS)

    Shamzhy, Mariya; Opanasenko, Maksym; Shvets, Oleksiy; ?ejka, Ji?í

    2013-08-01

    Catalytic behavior of isomorphously substituted B-, Al-, Ga-, and Fe-containing extra-large pore UTL zeolites was investigated in Knoevenagel condensation involving aldehydes, Pechmann condensation of 1-naphthol with ethylacetoacetate, and Prins reaction of ?-pinene with formaldehyde and compared with large-pore aluminosilicate zeolite BEA and representative Metal-Organic-Frameworks Cu3(BTC)2 and Fe(BTC). The yield of the target product over the investigated catalysts in Knoevenagel condensation increases in the following sequence: (Al)BEA < (Al)UTL < (Ga)UTL < (Fe)UTL < Fe(BTC) < (B)UTL < Cu3(BTC)2 being mainly related to the improving selectivity with decreasing strength of active sites of the individual catalysts. The catalytic performance of Fe(BTC), containing the highest concentration of Lewis acid sites of the appropriate strength is superior over large-pore zeolite (Al)BEA and B-, Al-, Ga-, Fe-substituted extra-large pore zeolites UTL in Prins reaction of ?-pinene with formaldehyde and Pechmann condensation of 1-naphthol with ethylacetoacetate.

  12. Identification of 4-methylspinaceamine - a Pictet – Spengler condensation reaction product of histamine with acetaldehyde - in human urine

    Microsoft Academic Search

    Takeshi Ohya; Masaru Niitsu

    2005-01-01

    This study reports the first identification of 4-methylspinaceamine (4-MSPA)-a Pictet Spengler condensation reaction product of histamine with acetaldehyde-in human urine. 4-MSPA was identified and quantified as follows: the target compound was partially purified by solvent extraction from a urine sample spiked with N-methylpiperazine (N-MP) as an internal standard, then derivatized to a naphthylthiourea derivative with 1-naphthylisothiocyanate (NITC) and finally analyzed

  13. Formation of a fluorescent adduct in the reaction of 2'-deoxyadenosine with a malonaldehyde-acetaldehyde condensation product.

    PubMed

    Le Curieux, F; Pluskota, D; Munter, T; Sjöholm, R; Kronberg, L

    1998-09-01

    Malonaldehyde (malondialdehyde, MDA) was reacted with 2'-deoxyadenosine in buffered aqueous solution. HPLC analyses of the reaction mixtures showed that, besides the two previously characterized N6-propenal (M1dA) and N6-oxazocinyl (M3dA) adenine adducts, a third compound eluting at longer retention time was formed. The compound generated a strong peak in the chromatogram recorded by a fluorescence detector. The new compound was isolated by preparative C18 chromatography, and its structure was characterized by UV absorbance, fluorescence emission, 1H and 13C NMR spectroscopy, and mass spectrometry. The product was identified as 9-(2'-deoxyribosyl)-6-(3,5-diformyl-4-methyl-1, 4-dihydro-1-pyridyl)purine (M2AA-dA). The yield of the product was 0.8% following 7 days of reaction at 37 degreesC and pH 4.6. Lower yields were obtained at higher pH conditions. By the addition of acetaldehyde, the yield increased about 10-fold at all studied pH conditions. The adduct was most likely formed by an initial condensation of two molecules of malonaldehyde with one molecule of acetaldehyde followed by reaction of the condensation product with the exocyclic amino group of 2'-deoxyadenosine. The identification of this adduct shows that acetaldehyde may react with DNA bases also through an initially formed malonaldehyde-acetaldehyde condensation product. PMID:9760272

  14. Quantum chemical approach for condensed-phase thermochemistry (II): Applications to formation and combustion reactions of liquid organic molecules

    NASA Astrophysics Data System (ADS)

    Ishikawa, Atsushi; Nakai, Hiromi

    2015-03-01

    The harmonic solvation model (HSM), which was recently developed for evaluating condensed-phase thermodynamics by quantum chemical calculations (Nakai and Ishikawa, 2014), was applied to formation and combustion reactions of simple organic molecules. The conventional ideal gas model (IGM) considerably overestimated the entropies of the liquid molecules. The HSM could significantly improve this overestimation; mean absolute deviations for the Gibbs energies of the formation and combustion reactions were (49.6, 26.7) for the IGM and (9.7, 5.4) for the HSM in kJ/mol.

  15. Proposal for New Experimental Tests of the Bose-Einstein Condensation Mechanism for Low Energy Nuclear Reaction and Transmutation Processes in Deuterium Loaded Micro and Nano Scale Cavities

    Microsoft Academic Search

    Yeong E. Kim; David S. Koltick; Ronald G. Reifenberger; Alexander L. Zubarev

    Most of experimental results of low energy nuclear reaction (LENR) reported so far cannot be reproduced on demand. There have been persistent experimental results indicating that the LENR and transmutation processes in condensed matters (LENRTPCM) are surface phenomena rather than bulk phenomena. Recently proposed Bose-Einstein condensation (BEC) mechanism may provide a suitable theoretical description of the surface phenomena. New experiments

  16. Anomalous nuclear reactions in condensed matter: Recent results and open questions

    NASA Astrophysics Data System (ADS)

    Jones, S. E.; Palmer, E. P.; Czirr, J. B.; Decker, D. L.; Jensen, G. L.; Thorne, J. M.; Taylor, S. F.; Rafelski, J.

    1990-06-01

    We have observed clear signatures for neutron emission during deuteron infusion into metals, implying the occurrence of nuclear fusion in condensed matter near room temperature. The low-level nuclear phenomenon has been demonstrated in collaborative experiments at Brigham Young University, at the Gran Sasso laboratory in Italy, and at the Los Alamos National Laboratory. We have shown that neutron emission can be induced in metals using both electrochemical and variational temperature/pressure means to generate non-equilibrium conditions. Observed average neutron emission rates are approximately 0.04-0.4 no/ s. Current efforts focus on trying to understand and control the phenomenon. In particular, we wish to understand the correlation of neutron yields with parameters such as hydrogen/metal ion ratio, pressure (induced, for example, by electrical field or gas pressure or mechanical pressure), temperature variation, hydride phase changes, and surface conditions, e.g., a palladium coating on titanium. We want to know if fusion arises due to the close proximity of the deuterons in the lattice (piezonuclear fusion), or possibly from “microscopic hot fusion”, accompanying strong electric fields at propagating cracks in the hydride. The latter interpretation would imply neutron emission in bursts. Our experiments show clear evidence for emission of ˜102 neutrons in bursts lasting <128 ?s, although random neutron-singles emissions were also observed. Experiments now underway to compare the d-d, and p-d, and d-t reaction rates will be important to a consistent description of the new phenomenon. Careful scrutiny of this effect could increase our understanding of heat, helium-3, and tritium production in the earth, other planets, and even the stars.

  17. Dehydration of the stratosphere

    Microsoft Academic Search

    M. R. Schoeberl; A. E. Dessler

    2011-01-01

    Domain filling, forward trajectory calculations are used to examine the global dehydration processes that control stratospheric water vapor. As with most Lagrangian models of this type, water vapor is instantaneously removed from the parcel to keep the relative humidity (RH) with respect to ice from exceeding saturation or a specified super-saturation value. We also test a simple parameterization of stratospheric

  18. Oxidative condensation reactions of (diethylenetriamine)cobalt(III) complexes with substituted bis(pyridin-2-yl)methane ligands

    NASA Astrophysics Data System (ADS)

    Zhou, Xiangting; Hockless, David C. R.; Willis, Anthony C.; Jackson, W. Gregory

    2005-04-01

    The synthesis and characterisation of Co(III) complexes derived from a condensation reaction with a central or terminal nitrogen of a dien ligand and the ?-carbon of a range of substituted bis(pyridin-2-yl)methane ligands are described. Aerial oxidation of bpm {bis(pyridin-2-yl)methane with Co(II)/dien or direct reaction with Co(dien)Cl 3 provided in low yield a single C-N condensation product 1 (at the primary terminal NH 2) after the pyridyl -CH 2- is formally oxidised to -CH +-. The methyl substituted ligand bpe {1,1-bis(pyridin-2-yl)ethane} behaves likewise, except both terminal (prim) and central (sec) amines condense to yield isomeric products 2 and 3. Two of these three materials have been characterised by single crystal X-ray crystallography. The corresponding reactions for the bis(pyridyl) ligand bpk {bis(pyridin-2-yl)ketone} provided C-N condensation products without the requirement for oxidation at the ?-C center; two carbinolamine complexes in different geometrical configurations resulted, mer-anti-[Co(dienbpc)Cl]ZnCl 4, 5, and unsym- fac-[Co(dienbpc)Cl]ZnCl 4, 6, {dienbpc=[2-(2-aminoethylamino)-ethylamino]-di-pyridin-2-yl-methanol}. In addition, a novel complex, [Co(bpk)(bpd-OH)Cl]ZnCl 4, 4, in which one bidentate N, N-bonded bpk ligand and one tridentate N, O, N-bonded bpd (the diol from bpk+OH -) were coordinated, was obtained via the Co(II)/O 2 synthetic route. When the bpc ligand (bpc=bis(pyridin-2-yl)methanol) was employed directly as a reagent along with dien, no condensation reactions were observed, but rather a single isomeric complex [Co(dien)(bpc)]Cl.ZnCl 4, 7, in which the ligand bpc acted as a N,N,O-bonded tridentate ligand rather than as a N,N-bidentate ligand was isolated. 13C, 1D and 2D 1H NMR studies are reported for all the complexes; they establish the structures unambiguously.

  19. Rate-promoting vibrations and coupled hydrogen-electron transfer reactions in the condensed phase: A model for enzymatic catalysis

    NASA Astrophysics Data System (ADS)

    Mincer, Joshua S.; Schwartz, Steven D.

    2004-04-01

    A model is presented for coupled hydrogen-electron transfer reactions in condensed phase in the presence of a rate promoting vibration. Large kinetic isotope effects (KIEs) are found when the hydrogen is substituted with deuterium. While these KIEs are essentially temperature independent, reaction rates do exhibit temperature dependence. These findings agree with recent experimental data for various enzyme-catalyzed reactions, such as the amine dehydrogenases and soybean lipoxygenase. Consistent with earlier results, turning off the promoting vibration results in an increased KIE. Increasing the barrier height increases the KIE, while increasing the rate of electron transfer decreases it. These results are discussed in light of other views of vibrationally enhanced tunneling in enzymes.

  20. Development of Encapsulation Dehydration

    Microsoft Academic Search

    Florent Engelmann; Maria-Teresa Gonzalez Arnao; Yongjie Wu; Roosevelt Escobar

    The application of cryopreservation to plants is relatively recent as the first report of successful cryopreservation was\\u000a published by Sakai in 1960 with silver birch twigs, and in-vitro cultured flax cells were frozen by Quatrano in 1968. The first protocols developed in the 1980s included pre-treatment with\\u000a cryoprotectants followed by controlled rate cooling. These protocols were based on freeze-induced dehydration

  1. Production of Clean Transportation Fuel Dimethylether by Dehydration of Methanol Over Nafion Catalyst

    Microsoft Academic Search

    Dilek Varõ; Timur Dou

    Dimethylether (DME) which is a very attractive synthetic transportation fuel alternate is synthesized by the dehydration reaction of methanol over nafion as the catalyst. The objective is to test the activity of this catalyst in methanol dehydration reaction. Experiments carried out in a vapor phase flow reactor in a temperature range of 120-220 o C and with a space time

  2. Experimental and phenomenological comparison between Piezonuclear reactions and Condensed Matter Nuclear Science phenomenology

    Microsoft Academic Search

    F. Cardone; R. Mignani; A. Petrucci

    2011-01-01

    The purpose of this paper is to place side by side the experimental results of Piezonu- clear reactions, which have been recently unveiled, and those collected during the last twenty years of experiments on low energy nuclear reactions (LENR). We will briefy re- port the results of our campaign of piezonuclear reactions experiments where ultrasounds and cavitation were applied to

  3. Mechanism of Formation of Nanocrystalline ZnO Particles through the Reaction of [Zn(acac) 2] with NaOH in EtOH

    Microsoft Academic Search

    Yoichi Inubushi; Ryoji Takami; Mitsunobu Iwasaki; Hiroaki Tada; Seishiro Ito

    1998-01-01

    The mechanism of formation of nanocrystalline ZnO particles from the reaction of zinc acetylacetonate ([Zn(acac)2]) with 2-equivalent NaOH in boiling EtOH was investigated by characterizing the particles and following the transformation of acac moieties. The reaction was found to proceed via hydrolysis of zinc ethoxide derivatives, followed by dehydration–condensation reactions. High-resolution solid-state CP-MAS13C NMR measurements indicate that the ZnO particles

  4. Preparation of sodium borohydride by the reaction of MgH 2 with dehydrated borax through ball milling at room temperature

    Microsoft Academic Search

    Z. P. Li; N. Morigazaki; B. H. Liu; S. Suda

    2003-01-01

    A convenient method was developed to synthesize NaBH4 by the reaction of MgH2 with Na2B4O7 through ball milling at room temperature. In order to improve the sodium borohydride yield, Na compounds were added to compensate the Na insufficiency in reactants when MgH2 instead of NaH was used as the reducing agent. It was found that Na2CO3 addition was better than

  5. Anomalous nuclear reactions in condensed matter: Recent results and open questions

    Microsoft Academic Search

    S. E. Jones; E. P. Palmer; J. B. Czirr; D. L. Decker; G. L. Jensen; J. M. Thorne; S. F. Taylor; J. Rafelski

    1990-01-01

    We have observed clear signatures for neutron emission during deuteron infusion into metals, implying the occurrence of nuclear\\u000a fusion in condensed matter near room temperature. The low-level nuclear phenomenon has been demonstrated in collaborative\\u000a experiments at Brigham Young University, at the Gran Sasso laboratory in Italy, and at the Los Alamos National Laboratory.\\u000a We have shown that neutron emission can

  6. Kinetics of volatile extraction from carbonaceous chondrites: Dehydration of talc

    NASA Technical Reports Server (NTRS)

    Bose, Kunal; Ganguly, Jibamitra

    1991-01-01

    Carbonaceous chondrites are believed to be the primary constituents of near-Earth asteroids and Phobos and Deimos, and are potential resources of fuels that may be exploited for future planetary missions. Calculations of equilibrium phase relations suggest that talc (Ta) and antigorite (Ant) are likely to be the major hydrous phases in the C1 and C2 meteorites (Ganguly and Saxena, 1989), which constitute the most volatile rich classes of carbonaceous chondrites. The dehydration kinetics of talc are studied as a function of temperature, grain size, composition and fluid fugacity, as part of a systematic study of the reaction kinetics of the volatile bearing phases that are either known or likely to be present in carbonaceous chondrites. The dehydration kinetics were investigated at 1 bar, 775 to 875 C by monitoring the in-situ weight loss as a function of time of a natural talc. The talc platelets had a dimension of 0.8 to 1 micron. The run durations varied from 233.3 hours at 775 C (48 percent dehydration) to 20.8 hours at 875 C (80 pct. dehydration). The results can be adequately represented by a given rate equation. Theoretical analysis suggests that the reduction in the concentration of H2O in the environment of dehydrating talc, as would be encountered in processing chondritic materials, will have negligible effect on the rate of dehydration, unless there is a change of reaction mechanism owing to the presence of other volatile species.

  7. The Aldol Addition and Condensation: The Effect of Conditions on Reaction Pathway

    ERIC Educational Resources Information Center

    Crouch, R. David; Richardson, Amie; Howard, Jessica L.; Harker, Rebecca L.; Barker, Kathryn H.

    2007-01-01

    The reaction of a ketone and an aldehyde in aqueous Na[subscript 2]CO[subscript 2] is described. This experiment is performed in the absence of strong bases or organic solvents and offers the opportunity for students to observe the critical role that reaction temperature and base strength have in determining the product of the base-mediated…

  8. Dehydration-induced luminescence in clay minerals

    NASA Technical Reports Server (NTRS)

    Coyne, L. M.; Lahav, N.; Lawless, J. G.

    1981-01-01

    Reports of triboluminescent phenomena in organic crystalline materials prompted a search for related processes in clay minerals. The reported extensive mechanical distortion produced on freezing and drying of montmorillonite was particularly interesting because of studies of condensation reactions in a wet/dry cycled reaction sequence. The discovery of an unusual luminescent process in several clay minerals is reported and its characteristics are described.

  9. 7 CFR 989.12 - Dehydrator.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...Nuts), DEPARTMENT OF AGRICULTURE RAISINS PRODUCED FROM GRAPES GROWN IN CALIFORNIA Order Regulating Handling Definitions...Dehydrator means any person who produces raisins by dehydrating grapes by artificial...

  10. 7 CFR 989.12 - Dehydrator.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...NUTS), DEPARTMENT OF AGRICULTURE RAISINS PRODUCED FROM GRAPES GROWN IN CALIFORNIA Order Regulating Handling Definitions...Dehydrator means any person who produces raisins by dehydrating grapes by artificial...

  11. 7 CFR 989.12 - Dehydrator.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...NUTS), DEPARTMENT OF AGRICULTURE RAISINS PRODUCED FROM GRAPES GROWN IN CALIFORNIA Order Regulating Handling Definitions...Dehydrator means any person who produces raisins by dehydrating grapes by artificial...

  12. Models of glycolysis: Glyceraldehyde as a source of energy and monomers for prebiotic condensation reactions

    NASA Technical Reports Server (NTRS)

    Weber, A. L.

    1986-01-01

    All organisms require energy in a chemical form for maintenance and growth. In contemporary life this chemical energy is obtained by the synthesis of the phosphoanhydride bonds of ATP. Among the biological processes that yield ATP, fermentation is generally considered primitive, because it operates under anaerobic conditions by substrate-level phosphorylation which does not require compartmentation by membranes. Fermentation by the glycolytic pathway, which is found in almost every living cell, is an especially attractive energy source for primitive life. Glycolysis not only produces useful chemical energy (ATP), but intermediates of this pathway are also involved in amino acid synthesis and photosynthetic carbon-fixation. It is believed that energy and substrates needed for the origin of life were provided by nonenzymatic chemical reactions that resemble the enzyme-mediated reactions of glycolysis. These nonenzymatic reactions would have provided a starting point for the evolutionary development of glycolysis.

  13. Reactions of pulsed laser produced boron and nitrogen atoms in a condensing argon stream

    E-print Network

    Martin, Jan M.L.

    important because thin films of boron mtride can be grown by vapor deposition for high-temperature coatings dilution in argon favored diboron species. At low laser power with minimum radiation, the dominant reaction. The vapors so formed have been examined by mass spectroscopy2'3 and by matrix electron spin resonance (ESR

  14. Experimental study of dehydration induced seismicity and fracture

    NASA Astrophysics Data System (ADS)

    Meredith, P.; Burlini, L.; Feenstra, A.

    2003-04-01

    It is well-known that elevated pore fluid pressures in rocks leads to weakening and embrittlement through the principal of effective stress. If the pore fluid pressure exceeds the confining pressure by any appreciable margin, then the material can fail by hydraulic fracture. We have measured the output of seismicity, as acoustic emission (AE) energy, during slow heating of samples of gypsum and diasporite to beyond their equilibrium dehydration temperatures. Experiments were performed on core samples measuring approximately 15mm in diameter by 27mm long under a hydrostatic stress of 200 and 300 MPa in a Paterson high-pressure/high-temperature internally-heated gas apparatus. AEs were recorded via two piezoelectric transducers embedded in the sample end caps away from the hot zone at the ends of two hollow zirconia buffer rods. Drained and undrained conditions were achieved by placing either permeable or impermeable discs between the samples and the buffer rods. At 200 MPa, gypsum dehydrates to bassinite and water around 100 0C, and diasporite dehydrates to corundum around 400 0C. We observed microseismicity in all cases in the form of high-energy AE events confined to a narrow temperature interval somewhat above the equilibrium dehydration temperature. This overstep is due to the heating rate in our experiments being faster than for equilibrium studies. The high-energy AE events were characterised by very long durations, which is typical of a cascade of multiple overlapping events which cannot be individually resolved. Under drained conditions, the gypsum samples showed a clear volume reduction due to the dehydration reaction and consequent compaction. By contrast, the diasporite samples maintained the same dimensions, but lost weight, implying that no compaction occurred during dehydration. Our results demonstrate conclusively that seismicity can be generated by dehydration reactions even in the absence of a deviatoric stress. This has potentially important implications for earthquake nucleation both in the crust and in subducting lithospheric plates.

  15. Condensation reactions of guanidines with bis-electrophiles: Formation of highly nitrogenous heterocycles.

    PubMed

    Arnold, David M; Laporte, Matthew G; Anderson, Shelby M; Wipf, Peter

    2013-09-01

    2-Amino-1,4-dihydropyrimidines were reacted with bis-electrophiles to produce novel fused bi-pyrimidine, pyrimido-aminotriazine, and pyrimido-sulfonamide scaffolds. In addition, a quinazoline library was constructed using a guanidine Atwal-Biginelli reaction with 1-(quinazolin-2-yl)guanidines. The product heterocycles have novel constitutions with high nitrogen atom counts and represent valuable additions to screening libraries for the discovery of new modulators of biological targets. PMID:23976798

  16. Experimental and phenomenological comparison between Piezonuclear reactions and Condensed Matter Nuclear Science phenomenology

    E-print Network

    Cardone, F; Petrucci, A

    2011-01-01

    The purpose of this paper is to place side by side the experimental results of Piezonu- clear reactions, which have been recently unveiled, and those collected during the last twenty years of experiments on low energy nuclear reactions (LENR). We will briefy re- port the results of our campaign of piezonuclear reactions experiments where ultrasounds and cavitation were applied to solutions of stable elements. These outcomes will be shown to be compatible with the results and evidences obtained from low energy nuclear reac- tion experiments. Some theoretical concepts and ideas, on which our experiments are grounded, will be sketched and it will be shown that, in order to trigger our measured effects, it exists an energy threshold, that has to be overcome, and a maximum inter- val of time for this energy to be released to the nuclear system. Eventually, a research hypothesis will be put forward about the chance to raise the level of analogy from the mere comparison of results up to the phenomenological level. H...

  17. Experimental and phenomenological comparison between Piezonuclear reactions and Condensed Matter Nuclear Science phenomenology

    E-print Network

    F. Cardone; R. Mignani; A. Petrucci

    2011-03-06

    The purpose of this paper is to place side by side the experimental results of Piezonu- clear reactions, which have been recently unveiled, and those collected during the last twenty years of experiments on low energy nuclear reactions (LENR). We will briefy re- port the results of our campaign of piezonuclear reactions experiments where ultrasounds and cavitation were applied to solutions of stable elements. These outcomes will be shown to be compatible with the results and evidences obtained from low energy nuclear reac- tion experiments. Some theoretical concepts and ideas, on which our experiments are grounded, will be sketched and it will be shown that, in order to trigger our measured effects, it exists an energy threshold, that has to be overcome, and a maximum inter- val of time for this energy to be released to the nuclear system. Eventually, a research hypothesis will be put forward about the chance to raise the level of analogy from the mere comparison of results up to the phenomenological level. Here, among the various evidences collected in LENR experiments, we will search for hints about the overcome of the energy threshold and about the mechanism that releases the loaded energy in a suitable interval of time.

  18. Reaction engineering of co-condensing (methyl)ethoxysilane mixtures: Kinetic characterization and modeling

    SciTech Connect

    RANKIN,STEPHEN E.; MCCORMICK,ALON V.

    2000-01-26

    Molecular homogeneity frequently plays a decisive role in the effective application of organically modified silicate copolymers. However, methods of directly characterizing copolymerization extent in siloxanes generated from mixed alkoxysilanes are not always available or convenient. The authors present an alternative tool for determining kinetic parameters for models of alkoxysilane hydrolytic copolycondensation. Rather than restricting attention to single step batch reactors, they use a semibatch reactor with varying time of injection of one component. They describe the fitting method and show that all necessary kinetic parameters can be determined from a series of ordinary {sup 29}Si NMR data in a straightforward case study: copolymerization of dimethyldiethoxy silane and trimethylethoxysilane. Under conditions providing no direct {sup 29}Si NMR signature of copolymerization, they find kinetic trends consistent with those previously reported. As further validation, the results of a new series of experiments (varying the ratio of mono-functional to difunctional monomer) are predicted by the semibatch copolymerization model and measured parameters. Based on these results, they are able to calculate the molecular homogeneity in the copolymer products investigated. Even for this relatively simple system, the optimal injection time is a complex function of residence time, but early injection of the faster-condensing monomer gives the best homogeneity at long residence times.

  19. Conservation of yeasts by dehydration

    Microsoft Academic Search

    Martin Beker; Alexander Rapoport

    The presented material concerns the theoretical basis for obtaining high-quality active dry biopreparations. It deals with the present understanding of anabiosis, contains data on yeast resistance against dehydration and the limits for preserving the viability of microorganisms in anabiosis. The process of water transport in yeast biomass during dehydration is discussed.\\u000a The changes and transformations in yeast cells occuring after

  20. Dehydration-driven topotaxy in subduction zones

    NASA Astrophysics Data System (ADS)

    Padrón-Navarta, José Alberto; Tommasi, Andréa; Garrido, Carlos J.

    2014-05-01

    Mineral replacement reactions play a fundamental role in the chemistry and the strength of the lithosphere. When externally or internally derived fluids are present, interface-coupled dissolution-precipitation is the driving mechanism for such reactions [1]. One of the microstructural features of this process is a 3D arrangement of crystallographic axes across internal interfaces (topotaxy) between reactant and product phases. Dehydration reactions are a special case of mineral replacement reaction that generates a transient fluid-filled porosity. Among others, the dehydration serpentinite is of special relevance in subduction zones because of the amount of fluids involved (potentially up to 13 wt.%). Two topotatic relationships between olivine and antigorite (the serpentine mineral stable at high temperature and pressure) have been reported in partially hydrated mantle wedge xenoliths [2]. Therefore, if precursor antigorite serpentine has a strong crystallographic preferred orientation (CPO) its dehydration might result in prograde peridotite with a strong inherited CPO. However for predicting the importance of topotactic reactions for seismic anisotropy of subduction zones we also need to consider the crystallization orthopyroxene + chlorite in the prograde reaction and, more importantly, the fact that this dehydration reaction produces a transient porosity of ca. 20 % vol. that results in local fluctuations of strain during compaction and fluid migration. We address this issue by a microstructural comparison between the CPO developed in olivine, orthopyroxene and chlorite during high-pressure antigorite dehydration in piston cylinder experiments (at 750ºC and 20 kbar and 1000ºC and 30 kbar, 168 h) and that recorded in natural samples (Cerro del Almirez, Betic Cordillera, Spain). Experimentally developed CPOs are strong. Prograde minerals show a significant inheritance of the former antigorite foliation. Topotactic relations are dominated by (001)atg//(100)ol// (100)opx//(001)chl. The relation [010]atg// [001]ol //[001]opx can also be inferred but it is weaker. Similar topotactic relations are observed in the Cerro del Almirez samples, but the CPOs are weaker and more complex. The complexity arises from constant interfacial angles and systematic low-index interfacial contacts between orthopyroxene-olivine-chlorite (e.g. (001)chl // (100)opx). As a consequence the inheritance from the antigorite serpentinite is partially obliterated. Compaction-related microstructural features are also present including: (1) smooth bending of the former foliation and diffuse olivine veinlets perpendicular to it, (2) gradual crystallographic misorientation (up to 15º) of prismatic enstatite due to buckling, (3) localized orthoenstatite(Pbca)/low clinoenstatite (P21/c) inversion, and (4) brittle fracturing of prismatic enstatite wrapped by plastically deformed chlorite. These observations suggest that topotactic crystrallographic relations are dominant in undrained systems, but that the mechanisms allowing for compaction and fluid draining significantly affect the final texture in drained systems. Because the second case prevails in subduction zones, compaction mechanisms need to be better understood for modelling the development of CPOs after foliated protoliths in the slab and the mantle wedge. [1] Putnis, A., 2009. Reviews in Mineralogy and Geochemistry 70, 87-124. [2] Boudier, F., et al. 2010 J. Petrology 51, 495-512.

  1. Dehydrated fluid and seismic deformation in deep subduction zone

    NASA Astrophysics Data System (ADS)

    Okamoto, K.

    2013-12-01

    It has been considered that there is a correlation between the double seismic zone and metamorphic dehydration reaction in deep slab. The location of the upper limits of the upper seismic plane correspond to metamorphic facies boundary where H2O contents change in subducting crust; numerous earthquakes from 60 to 110 km depths in the lawsonite-blueschist facies, many earthquakes in the lower crust of the slab from 110 to 150 km depths in the lawsonite-amphibole eclogite facies and few earthquakes in the lawsonite eclogite facies. There is still minor amount of H2O present in the lawsonite eclogite facies. The dehydrated fluid is not the only trigger to cause slab earthquake. Recent petrological researches have revealed that both blueschist and lawsonite eclogite are stable in the same pressure and temperature condition because chemical variation including water content creates both lawsonite-amphibole eclogite and lawsonite eclogite in different portion of subducted crust. It would cause stress localization and hydro-fracturing in the slab in the shallower part (depths ranging from 60 to 110 km) and lawsonite amphibole eclogite in the lower crust in the deeper part (from 110 to 150 km depth) in the upper seismic plane. The lower plane of the double seismic zone, is considered to be related to dehydration reaction in the slab. Metamorphic olivine has been described in vein from serpentinite mylonite. The vein was created by dehydration reaction to decompose antigorite under shear deformation. In the cold slab beneath Tohoku arc, the reaction has a negative slope in P-T space and forms olivine+orthopyroxene+fluid. In the warm slab beneath SW Japan, the reaction has a positive slope in P-T space and forms olivine+talc+fluid. The above these dehydration reactions are well-described in the serpentinite from high P/T metamorphic belt from Spain, and Italy, respectively.

  2. Experimental evidence for condensation reactions between sugars and proteins in carbonate skeletons

    NASA Astrophysics Data System (ADS)

    Collins, M. J.; Westbroek, P.; Muyzer, G.; de Leeuw, J. W.

    1992-04-01

    Melanoidins, condensation products formed from protein and polysaccharide precursors, were once thought to be an important geological sink for organic carbon. The active microbial recycling of the precursors, coupled with an inability to demonstrate the formation of covalent linkages between amino acids and sugars in melanoidins, has shaped a powerful argument against this view. Yet, melanoidins may still be an abundant source of macromolecules in fossil biominerals such as shells, in which the proteins and polysaccharides are well protected from microbial degradation. We have modelled diagenetic changes in a biomineral by heating at 90°C mixtures of protein, polysaccharides and finely ground calcite crystals in sealed glass vials. Changes to the protein bovine serum albumin (BSA, fraction V) were monitored by means of gel electrophoresis and immunology. In the presence of water, BSA was rapidly hydrolyzed and remained immunologically reactive for less than 9 h. Under anhydrous conditions the protein was immunologically reactive for the whole period of the experiment (1281 h), unless mono- or disaccharide sugars were also present. In the presence of these reactive sugars, browning, a discrete increase in molecular weight of the protein and a concomitant loss of antigenicity confirmed that the sugars were attaching covalently to the protein, forming melanoidins. The de novo formation of products cross-reactive with antibodies raised against organic matter isolated from the shells of a fossil mollusc ( Mercenaria mercenaria) indicated that at least in part the model simulated natural diagenesis. We roughly estimate that, at the global scale, 2.4 × 10 6 tonnes of calcified tissue matrix glycoproteins is processed annually through the melanoidin pathway. This amount would be equivalent to 7 per mil of the total flux of organic carbon into marine sediments.

  3. Osmotic Dehydration Kinetics of Pineapple Wedges using Palm Sugar

    Microsoft Academic Search

    Parjoko; M. Shafiur Rahman; Ken A. Buckle; Conrad O. Perera

    1996-01-01

    Osmotic dehydration kinetics of pineapple wedges was studied using palm sugar at different syrup concentration and temperature. Equilibrium kinetics were presented by defining equilibrium constants and nonequilibrium period of water loss and solid gain followed the model based on mass balance and zero order reaction kinetics. At constant temperature, the rate constants for both water and solids increased with increase

  4. Release of stored thermochemical energy from dehydrated salts

    Microsoft Academic Search

    Mehdi Ghommem; Ganesh Balasubramanian; Muhammad R. Hajj; William P. Wong; Jennifer A. Tomlin; Ishwar K. Puri

    2011-01-01

    Thermochemical materials, particularly salt hydrates, have significant potential for use in thermal energy storage applications. When a salt hydrate is heated to a threshold temperature, a chemical reaction is initiated to dissociate it into its anhydrous form and water vapor. The anhydrous salt stores the sensible energy that was supplied for dehydration, which can be later extracted by allowing cooler

  5. Self-Organizing Reactive Fluid Escape from Dehydrating Rocks

    NASA Astrophysics Data System (ADS)

    John, T.; Pluemper, O.; Podladchikov, Y.; Vrijmoed, J. C.; Scambelluri, M.

    2014-12-01

    Water escape from dehydrating rocks within the Earth's interior is a key process for long-term global water and element cycles, eg. at subduction zones a fluid escape mechanism must exist that prevents ocean water to be drained into the mantle. Existing fluid flow models require a priori physical assumptions (eg. preexisting porosity) and cannot resolve the evolution from initial fluid production to flow channelization. In order to develop a model of this evolution, we need to unravel natural laboratories that display the incipient dehydration stages and the micro- to macro-scale fluid escape route evolution. The Erro-Tobbio meta-serpentinites (Italy) provide a unique snapshot into these early dehydration stages, recording the breakdown of hydrous antigorite to anhydrous olivine plus fluid and the formation of an olivine-vein network. We find that dehydration, fluid pooling, and flow initiation are controlled by micro-scale compositional rock differences. Our model starts with a rock in which all water is stored in solid and any preexisting porosity is negligible (zero-porosity case). As the rock descents into the mantle increasing T will initiate dehydration reactions, dividing the rock continuously into a dry solid and a fluid-filled porosity. Spatially variable reaction progress results in dynamically evolving porosity/permeability and heterogeneous fluid-pore pressure distributions. Fluid-pressure gradient relaxation causes fluid flow and its thermodynamic feedback triggers reactions to progress, resulting in a self-amplifying process. Our new thermodynamic-mechanical model for reaction-porosity waves shows that fluid flow occurs solely in the reaction products and self-organizes into channelized fluid escape networks. This holds the key to formulating future quantitative models that address spatiotemporal processes such as the coupling between fluid release at depth and volcanic eruptions and the amounts of structurally bound water transferred into deep Earth.

  6. Catalytic solid substrate room temperature phosphorimetry for the determination of trace rhamnose based on its condensation reaction with calcein

    NASA Astrophysics Data System (ADS)

    Liu, Jia-Ming; Lin, Li-Ping; Wang, Hong-Xin; Lin, Shao-Qin; Zhang, Li-Hong; Cai, Wen-Lian; Lin, Xuan; Pan, You-Zhu; Wang, Xin-Xing; Li, Zhi-Ming; Jiao, Li; Cui, Ma-Lin

    2011-12-01

    Calcein (R) could not only emit strong and stable room temperature phosphorescence (RTP) on filter paper using I - as perturber, but also could be oxidized by H 2O 2 to form a non-phosphorescence compound (R'), resulting in the quenching of RTP signal of R. Moreover, the ortho-hydrogen of phenolic hydroxyl in R took condensation reaction with rhamnose (Rha) to produce non-phosphorescence compound (R-Rha) causing the RTP signal of R to further quench, and R-Rha was oxidized by H 2O 2 to form R' and Rha, bringing about the sharp RTP signal quenching of R. Thus, a new solid substrate room temperature phosphorimetry (SSRTP) for the determination of trace Rha based on its strong catalytic effect on H 2O 2 oxidizing R has been established, with the detection limit (LD) of 7.8 zg spot -1 (corresponding concentration: 2.0 × 10 -17 g ml -1, sample volume: 0.40 ?l spot -1). This method has been applied to determine trace Rha in cigarettes and jujubes, with the results coinciding well with those determined by a high performance liquid chromatography (HPLC). The component of R-Rha also was analyzed by means of HPLC, mass spectrometer and nuclear magnetic resonance (NMR) measurements. The mechanism of catalytic SSRTP for the determination of trace Rha was discussed.

  7. May eclogite dehydration cause slab fracturation ?

    NASA Astrophysics Data System (ADS)

    Loury, Chloé; Lanari, Pierre; Rolland, Yann; Guillot, Stéphane; Ganino, Clément

    2015-04-01

    Petrological and geophysical evidences strongly indicate that fluids releases play a fundamental role in subduction zones as in subduction-related seismicity and arc magmatism. It is thus important to assess quantitatively their origin and to try to quantify the amount of such fluids. In HP metamorphism, it is well known that pressure-dependent dehydration reactions occur during the prograde path. Many geophysical models show that the variations in slab physical properties along depth could be linked to these fluid occurrences. However it remains tricky to test such models on natural sample, as it is difficult to assess or model the water content evolution in HP metamorphic rocks. This difficulty is bound to the fact that these rocks are generally heterogeneous, with zoned minerals and preservation of different paragenesis reflecting changing P-T conditions. To decipher the P-T-X(H2O) path of such heterogeneous rocks the concept of local effective bulk (LEB) composition is essential. Here we show how standardized X-ray maps can be used to constrain the scale of the equilibration volume of a garnet porphyroblast and to measure its composition. The composition of this equilibrium volume may be seen as the proportion of the rock likely to react at a given time to reach a thermodynamic equilibrium with the growing garnet. The studied sample is an eclogite coming from the carboniferous South-Tianshan suture (Central Asia) (Loury et al. in press). Compositional maps of a garnet and its surrounding matrix were obtained from standardized X-ray maps processed with the program XMapTools (Lanari et al, 2014). The initial equilibration volume was modeled using LEB compositions combined together with Gibbs free energy minimization. P-T sections were calculated for the next stages of garnet growth taking into account the fractionation of the composition at each stage of garnet growth. The modeled P-T-X(H2O) path indicates that the rock progressively dehydrates during the prograde path, leading to a complete dehydration at the pressure peak conditions, (25 kbar and 510°C). The amount of water released during this stage is about 20 g/dm3. In this example, no hydration event is recorded during the exhumation, explaining the good preservation of the anhydrous eclogite. This study shows that garnet thermobarometry in eclogite may be used as a proxy for progressive oceanic crust dehydration as suggested by the models of Baxter & Caddick (2014). In contrast to such models, the estimations proposed in the present study are based on the measured composition of local domains in rock-samples and not on average bulk rock compositions. Complete dehydration of eclogites around 75 km corresponds to the maximum depth of most exhumed oceanic eclogites except for a few special cases. Moreover the distribution of seismicity along the slab shows that only few earthquakes do occur in the crust beyond this limit as compared to the seismicity above it. Consequently this example from a natural sample strongly suggests that the eclogite dehydration at this depth can cause slab fracturation and consequently enhance eclogite exhumation. Baxter, E.F. & Caddick, M.J. 2013. Garnet growth as a proxy for progressive subduction zone dehydration. Geology, 41, 643-646 Lanari, P., Vidal, O., De Andrade, V., Dubacq, B., Lewin, E., Grosch, E.G. & Schwartz, S. 2014. XMapTools: A MATLAB©-based program for electron microprobe X-ray image processing and geothermobarometry. Computers & Geosciences, 62, 227-240 Loury, C., Rolland, Y., Guillot, S., Mikolaichuk, A., Lanari, P., Bruguier, O. & Bosch, D. in press. Crustal-scale structure of South Tien Shan : implications for subduction polarity and Cenozoic reactivation. Geological Society of London, special publications

  8. Dehydration Kinetics of Volterra Gypsum: Experiments and Overview

    NASA Astrophysics Data System (ADS)

    Llana-Funez, S.; Wheeler, J.; Faulkner, D.

    2007-12-01

    Dehydration reactions are often envisaged as a triggering mechanism for seismicity in rocks under tectonic loads due to the reduction in effective pressure during the release of fluids that may eventually produce mechanical embrittlement. Understanding of metamorphic transformation in deforming rocks is even more important in fault zones where periods of seismic slip are reported. Dehydration of gypsum under controlled conditions, in laboratory experiments and in numerical models, provides information on deformation processes operating in seismically active regions and may be of help in understanding their cyclicity and their evolution. Two series of simple heating experiments of Volterra gypsum samples at room pressure, using intact and powdered specimens, provide reference data for further experiments under confining and differential stress during dehydration. Heating experiments were run at constant temperature between 80 degC and 140 °C in intact specimens and at 86 °C and 97 °C using powders with five different grain size fractions: <0.063, 0.063-0.125, 0.125-0.25, 0.25-0.5 and >0.5 mm. The complete dehydration of 1 mol of gypsum produces 1 mol of anhydrite and two moles of water generating a porosity of about 38% and implying a weight loss of 21% upon removal of water. The progressive loss of weight during dehydration was used as the method to estimate the progress of the reaction. The reaction is characterized by an initial stage under 10% reaction were reaction rate accelerates, which is followed by a linear stage for about 50 to 70% of the reaction and a final third stage with decelerating reaction rates. All tests run above 85 °C reached about 90% reaction. Those below 85 °C seem to converge to a lower final fraction (75%) suggesting partial dehydration, very likely to bassanite. The temperature dependence of the linear rates indicates in an Arrhenius plot that the full dehydration of gypsum has an activation enthalpy of 96 kJ/mol. The two temperatures tested with powdered specimens are consistent with this activation enthalpy, although the higher intercepts with the y-axis indicate that reaction rates are about one order of magnitude faster. This is interpreted in relation to the very large initial porosity of the un-compacted specimens (>45% porosity). There is an additional increase in rates in powdered specimens as the grain size decreases, however, the difference is marginal despite the eight-times difference in grain size. At laboratory deformation rates, gypsum behaves in a brittle-ductile mode by a mixture of plasticity (twinning) and cataclasis in discrete and short-lived bands. A first series of deformation tests on dry gypsum have also been run to set a reference for mechanical behaviour to be compared in the future with behaviour during syn-tectonic dehydration. The deformation tests were run at room temperature, at strain rates of 2x10-5s-1 and confining pressures of 13, 50, 100, 146, 190 MPa. Tests were run in a triaxial rig using 20 mm diameter by 45 mm length specimens. Stress-strain curves show well-defined yield points and an almost straight plastic behaviour with a slight strain hardening component, similar to previous work. Stress-strain curves have minor, episodic and short-lived stress drops that have been related with the development of cataclastic bands (Milsch and Scholz, 2005). The grain fracturing associated with the generation of these cataclastic bands during experimental deformation of gypsum will have an effect in the dehydration kinetics by providing fined-grained gypsum and thus high surface area to speed up the reaction.

  9. Microwave-Assisted Condensation Reactions of Acetophenone Derivatives and Activated Methylene Compounds with Aldehydes Catalyzed by Boric Acid under Solvent-Free Conditions.

    PubMed

    Brun, Elodie; Safer, Abdelmounaim; Carreaux, François; Bourahla, Khadidja; L'helgoua'ch, Jean-Martial; Bazureau, Jean-Pierre; Villalgordo, Jose Manuel

    2015-01-01

    We here disclosed a new protocol for the condensation of acetophenone derivatives and active methylene compounds with aldehydes in the presence of boric acid under microwave conditions. Implementation of the reaction is simple, healthy and environmentally friendly owing to the use of a non-toxic catalyst coupled to a solvent-free procedure. A large variety of known or novel compounds have thus been prepared, including with substrates bearing acid or base-sensitive functional groups. PMID:26111185

  10. Kinetic multi-layer model of gas-particle interactions in aerosols and clouds (KM-GAP): linking condensation, evaporation and chemical reactions of organics, oxidants and water

    NASA Astrophysics Data System (ADS)

    Shiraiwa, M.; Pfrang, C.; Koop, T.; Pöschl, U.

    2012-03-01

    We present a novel kinetic multi-layer model for gas-particle interactions in aerosols and clouds (KM-GAP) that treats explicitly all steps of mass transport and chemical reaction of semi-volatile species partitioning between gas phase, particle surface and particle bulk. KM-GAP is based on the PRA model framework (Pöschl-Rudich-Ammann, 2007), and it includes gas phase diffusion, reversible adsorption, surface reactions, bulk diffusion and reaction, as well as condensation, evaporation and heat transfer. The size change of atmospheric particles and the temporal evolution and spatial profile of the concentration of individual chemical species can be modeled along with gas uptake and accommodation coefficients. Depending on the complexity of the investigated system and the computational constraints, unlimited numbers of semi-volatile species, chemical reactions, and physical processes can be treated, and the model shall help to bridge gaps in the understanding and quantification of multiphase chemistry and microphysics in atmospheric aerosols and clouds. In this study we demonstrate how KM-GAP can be used to analyze, interpret and design experimental investigations of changes in particle size and chemical composition in response to condensation, evaporation, and chemical reaction. For the condensational growth of water droplets, our kinetic model results provide a direct link between laboratory observations and molecular dynamic simulations, confirming that the accommodation coefficient of water at ~270 K is close to unity (Winkler et al., 2006). Literature data on the evaporation of dioctyl phthalate as a function of particle size and time can be reproduced, and the model results suggest that changes in the experimental conditions like aerosol particle concentration and chamber geometry may influence the evaporation kinetics and can be optimized for efficient probing of specific physical effects and parameters. With regard to oxidative aging of organic aerosol particles, we illustrate how the formation and evaporation of volatile reaction products like nonanal can cause a decrease in the size of oleic acid particles exposed to ozone.

  11. Condensation reactions of 3-oxo-2-arylhydrazonopropanals with active methylene reagents: formation of 2-hydroxy- and 2-amino-6-substituted-5-arylazonicotinates and pyrido[3,2-c]cinnolines via 6?-electrocyclization reactions.

    PubMed

    Al-Mousawi, Saleh M; El-Apasery, Morsy A

    2012-01-01

    3-Oxo-3-phenyl-2-(p-tolylhydrazono)propanal (1a) undergoes condensation with ethyl cyanoacetate in acetic acid in the presence of ammonium acetate to yield either 2-hydroxy-6-phenyl-5-p-tolylazonicotinic acid ethyl ester (6a) or 2-amino-6-phenyl-5-ptolyl-azonicotinic acid ethyl ester (8), depending on the reaction conditions. Similarly, other 3-oxo-3-aryl-2-arylhydrazonopropanals 1a,b condense with active methylene nitriles 2c,d to yield arylazonicotinates 6b,c. In contrast, 2-[(4-nitrophenyl)-hydrazono]-3-oxo-3-phenyl-propanal (1c) reacts with ethyl cyanoacetate to yield ethyl 6-(4-nitrophenyl)-2-oxo-2,6-dihydropyrido[3,2–c]cinnoline-3-carboxylate (11), via a novel 6?-electrocyclization pathway. Finally, 3-oxo-2-(phenylhydrazono)-3-p-tolylpropanal (1d) condenses with 2a-c to yield pyridazinones 13a-c. PMID:22728352

  12. Proposal for New Experimental Tests of the Bose-Einstein Condensation Mechanism for Low-Energy Nuclear Reaction and Transmutation Processes in Deuterium Loaded - and Nano-Scale Cavities

    Microsoft Academic Search

    Yeong E. Kim; David S. Koltick; Ronald G. Reifenberger; Alexander L. Zubarev

    2006-01-01

    Most of experimental results of low-energy nuclear reaction (LENR) reported so far cannot be reproduced on demand. There have been persistent experimental results indicating that the LENR and transmutation processes in condensed matters (LENRTPCM) are surface phenomena rather than bulk phenomena. Recently proposed Bose-Einstein condensation (BEC) mechanism may provide a suitable theoretical description of the surface phenomena. New experiments are

  13. Home Dehydrators For Food Preservation

    Microsoft Academic Search

    J. F. Sullivan; H. Weber

    1982-01-01

    A method for drying and storing foods for home use is described. A study of convection and forced-air dehydrators disclosed that the forced-air type has the ability to dry faster and is the more efficient dryer at little extra cost. Safe food storage is assured with the use of humidity indicating cards. These cards, which contain a variety of absorbed

  14. Hypernatraemic dehydration and necrotizing enterocolitis

    Microsoft Academic Search

    A. J. Clarke; J. R. Sibert

    1985-01-01

    Severe hypernatraemic dehydration developed over the first twelve days of life in a breastfed infant girl. Upon oral rehydration with formula milk, no acute neurological problems arose, but she subsequently developed necrotizing enterocolitis. Intravenous rehydration may be preferred to the oral route in such infants.

  15. An investigation of the role of water on retrograde/condensation reactions and enhanced liquefaction yields. Quarterly progress report, January 1, 1994--March 31, 1994

    SciTech Connect

    Miknis, F.P.; Netzel, D.A.

    1994-04-01

    The results of coal swelling measurements using 1,4-dioxane as the swelling reagent for premoisturized coals (raw) and coal dried thermally, chemically, and with microwave radiation are presented. An increase in the swelling ratio relative to raw coal indicates a decrease in the amount of cross-linking in the coal. Conversely, a decrease in the ratio indicates an increase in cross-linking. The extent of cross-linking (as measured by 1,4-dioxane) for Texas, Black Thunder, and Eagle Butte Coals are about the same. Illinois {number_sign}6 coal appears to have less cross-linking relative to the other three coals. These results are expected on the basis of coal rank. The increase in cross linking is most pronounced for coals dried thermally and with microwave radiation. A decrease in the swelling ratios for all four coals suggests that cross-linking had occurred possibly due to partial devolatilization process. However, low temperature, chemical dehydration of the coals causes only a small or no change in the internal structure for Texas and Illinois {number_sign}6 coals whereas a significant decrease in the cross-linking structure for the Black Thunder and Eagle Butte coals is observed. It is possible that the solvent (CH{sub 3}OH) and products resulting from the chemical dehydrating (acetone and methanol) occupy the surface sites that water had before the reaction and thus preventing cross-linking to occur. These reagents can also promote swelling of coals and may account for some of the decrease in the cross-linking of the coal structure observed for the chemically dried coals.

  16. Effect of leaf dehydration duration and dehydration degree on PSII photochemical activity of papaya leaves.

    PubMed

    Liu, Meijun; Zhang, Zishan; Gao, Huiyuan; Yang, Cheng; Fan, Xingli; Cheng, Dandan

    2014-09-01

    Although the effect of dehydration on photosynthetic apparatus has been widely studied, the respective effect of dehydration duration and dehydration degree was neglected. This study showed that, when leaves dehydrated in air, the PSII activities of leaves decreased with the decline of leaf relative water content (RWC). Unexpectedly, when leaves dehydrated to same RWC, the decreases in Fv/Fm, ?o and RC/CSm were lower in leaves dehydrating at 43 °C than those at 25 °C. However, to reach the same RWC, leaves dehydrating at 43 °C experienced 1/6 of the dehydration duration for leaves dehydrating at 25 °C. To distinguish the respective effect of dehydration degree and dehydration duration on photosynthetic apparatus, we studied the PSII activities of leaves treated with different concentration of PEG solutions. Increasing dehydration degree aggravated the decline of Fv/Fm, ?o and RC/CSm in leaves with the same dehydration duration, while prolonging the dehydration duration also exacerbated the decline of Fv/Fm, ?o and RC/CSm in leaves with identical dehydration degree. With the same dehydration degree and duration, high temperature enhanced the decrease of Fv/Fm, ?o and RC/CSm in the leaves. When leaves dehydrated in air, the effect of high temperature was underestimated due to reduction of dehydration duration. The results demonstrated that, dehydration degree and duration both play important roles in damage to photosynthetic apparatus. We suggest that, under combined stresses, the effects of dehydration degree and duration on plants should be considered comprehensively, otherwise, partial or incorrect results may be obtained. PMID:24908568

  17. Slab dehydration recorded in subducted serpentine sea-mount

    NASA Astrophysics Data System (ADS)

    Okamoto, K.; Fukumura, S.; Ishimori, C.; Jung, H.

    2014-12-01

    It has been considered that there is a correlation between the double seismic zones and metamorphic dehydration reaction in deep slab. The lower seismic plane of the double seismic zone is considered to be located on the 600 oC isotherm in the subducting lithosphere. Antigorite terminal reaction is highly temperature sensitive around 600 oC. Therefore it has been proposed that the oceanic lithosphere was hydrated forming serpentine prior to subduction, then serpentine was decomposed to release fluid causing dehydration embrittlement in the slab. In order to unravel relation between dehydration and seismic deformation, we have investigated dehydration process of natural metamorphic rocks recording very cold geothermal history in the crust and lithosphere in the slab. Metamorphic olivine after antigorite has been described in Italian Alps and also from the Mt. Shiraga, Japan [1]. However, the olivine was formed with talc and fluid by antigorite breakdown reaction in pressures lower than 1.5 GPa. Spinifex olivine with opx in the Cerro del Almirez [2], is the product at pressures (P > 1.5 GPa) relevant to the lower seismic plane beneath Northeast Japan. It clearly indicates the presence of large amount of water facilitate crystallization of elongated olivine with opx. It is also supported by LPO pattern of olivines determined by EBSD. Fine-grained olivine-rich samples shows that Type-C fabric pattern is dominant, suggesting deformation under water-rich condition [3]. With metamorphic olivines, chlorite was also recrystallized, suggesting that water would be transported farther down to deep. The estimated dehydration reaction has a negative P-T slope at pressures higher than 1.5 GPa. The reaction is volume reducing reaction and the olivine-opx spinifex texture was formed under volume reducing reaction. In the warm slab beneath SW Japan, the reaction has a positive slope in P-T space and forms olivine+talc+fluid. From microstrucral and petrological analysis of the Serpentinite in the Sambagawa high P/T metamorphic rocks, we found that the olivine with talc, is preserved mainly in the vein along the shear crack in mylonitized serpentinite. References: [1] K. Okamoto et al., Geochemistry, 46 205-215 (2013). [2] V. Trommsdorff et al., CMP, 132, 139-148 (1998). [3] Jung H, Karato S., Science 293, 1460-1463 (2001)

  18. The physiological effects of dehydration caused by sweat loss. [athletes

    NASA Technical Reports Server (NTRS)

    Israel, S.

    1981-01-01

    The mechanisms of fluid loss in the human body while sweating due to physical exercise are discussed. Trained and untrained persons were examined and compared. Since sweat is hypotonous, a disruption in the hydrosalinic balance occurs; the consequences of this finding, also pertaining to the fluid and electrolytic substitution, are presented. Further explanations on the problem of dehydration refer to reactions of individual organ systems, to alterations in bodily capabilities as well as to questions relating to sex and age.

  19. Slab dehydration and deep water recycling through time

    NASA Astrophysics Data System (ADS)

    Magni, Valentina; Bouilhol, Pierre; van Hunen, Jeroen

    2015-04-01

    The fate of water in subduction zones is a key feature that influences the magmatism of the arcs, the rheology of the mantle, and the recycling of volatiles. We investigate the dehydration processes in subduction zones and their implications for the water cycle throughout Earth's history. We use a numerical tool that combines thermo-mechanical models with a thermodynamic database to examine slab dehydration for present-day and early Earth settings and its consequences for the deep water recycling. We investigate the reactions responsible for releasing water from the crust and the hydrated lithospheric mantle and how they change with subduction velocity, slab age, and mantle potential temperature. Our results show that faster slabs dehydrate over a wide area: they start dehydrating shallower and they carry water deeper into the mantle. A hotter mantle (i.e., early Earth setting) drives the onset of crustal dehydration slightly shallower, but, mostly, dehydration reactions are very similar to those occurring in present-day setting. However, for very fast slabs and very hot mantle epidote is involved as a dehydrating crustal phase. Moreover, we provide a scaling law to estimate the amount of water that can be carried deep into the mantle. We generally observe that a 1) 100°C increase in the mantle temperature, or 2) ~15 Myr decrease of plate age, or 3) decrease in subduction velocity of ~2 cm/yr all have the same effect on the amount of water retained in the slab at depth, corresponding to a decrease of ~2.2x105 kg/m2 of H2O. We estimate that for present-day conditions ~26% of the global influx water, or 7x108 Tg/Myr of H2O, is recycled into the mantle. Using a realistic distribution of subduction parameters, we illustrate that deep water recycling might still be possible in early Earth conditions, although its efficiency would generally decrease. Indeed, 0.5-3.7x108 Tg/Myr of H2O could still be recycled in the mantle at 2.8 Ga.

  20. Microfluidic Droplet Dehydration for Concentrating Processes in Biomolecules

    NASA Astrophysics Data System (ADS)

    Anna, Shelley

    2014-03-01

    Droplets in microfluidic devices have proven useful as picoliter reactors for biochemical processing operations such as polymerase chain reaction, protein crystallization, and the study of enzyme kinetics. Although droplets are typically considered to be self-contained, constant volume reactors, there can be significant transport between the dispersed and continuous phases depending on solubility and other factors. In the present talk, we show that water droplets trapped within a microfluidic device for tens of hours slowly dehydrate, concentrating the contents encapsulated within. We use this slow dehydration along with control of the initial droplet composition to influence gellation, crystallization, and phase separation processes. By examining these concentrating processes in many trapped drops at once we gain insight into the stochastic nature of the events. In one example, we show that dehydration rate impacts the probability of forming a specific crystal habit in a crystallizing amino acid. In another example, we phase separate a common aqueous two-phase system within droplets and use the ensuing two phases to separate DNA from an initial mixture. We further influence wetting conditions between the two aqueous polymer phases and the continuous oil, promoting complete de-wetting and physical separation of the polymer phases. Thus, controlled dehydration of droplets allows for concentration, separation, and purification of important biomolecules on a chip.

  1. Dehydration of brucite (Mg(OH)2) at high pressures detected by differential thermal analysis

    Microsoft Academic Search

    Masami Kanzaki

    1991-01-01

    The differential thermal analysis (DTA) technique has been applied in a multi-anvil high-pressure apparatus to study the dehydration reaction of brucite (Mg(OH)2) to periclase (MgO) plus H2O at 4 to 6 GPa. At 4 GHa and 1030°C, endothermic and exothermic peaks due to dehydration and rehydration were observed during heating and cooling cycles, respectively. These peaks were shifted to higher

  2. Interstellar Silicate Analogs for Grain-surface Reaction Experiments: Gas-phase Condensation and Characterization of the Silicate Dust Grains

    NASA Astrophysics Data System (ADS)

    Sabri, T.; Gavilan, L.; Jäger, C.; Lemaire, J. L.; Vidali, G.; Mutschke, H.; Henning, T.

    2014-01-01

    Amorphous, astrophysically relevant silicates were prepared by laser ablation of siliceous targets and subsequent quenching of the evaporated atoms and clusters in a helium/oxygen gas atmosphere. The described gas-phase condensation method can be used to synthesize homogeneous and astrophysically relevant silicates with different compositions ranging from nonstoichiometric magnesium iron silicates to pyroxene- and olivine-type stoichiometry. Analytical tools have been used to characterize the morphology, composition, and spectral properties of the condensates. The nanometer-sized silicate condensates represent a new family of cosmic dust analogs that can generally be used for laboratory studies of cosmic processes related to condensation, processing, and destruction of cosmic dust in different astrophysical environments. The well-characterized silicates comprising amorphous Mg2SiO4 and Fe2SiO4, as well as the corresponding crystalline silicates forsterite and fayalite, produced by thermal annealing of the amorphous condensates, have been used as real grain surfaces for H2 formation experiments. A specifically developed ultra-high vacuum apparatus has been used for the investigation of molecule formation experiments. The results of these molecular formation experiments on differently structured Mg2SiO4 and Fe2SiO4 described in this paper will be the topic of the next paper of this series.

  3. Interstellar silicate analogs for grain-surface reaction experiments: Gas-phase condensation and characterization of the silicate dust grains

    SciTech Connect

    Sabri, T.; Jäger, C. [Laboratory Astrophysics Group of the Max Planck Institute for Astronomy at the Friedrich Schiller University Jena Institute of Solid State Physics, Helmholtzweg 3, D-07743 Jena (Germany); Gavilan, L.; Lemaire, J. L.; Vidali, G. [Observatoire de Paris/Université de Cergy-Pontoise, 5 mail Gay Lussac, F-95000 Cergy-Pontoise (France); Mutschke, H. [Laboratory Astrophysics Group of the Astrophysical Institute and University Observatory, Friedrich Schiller University Jena Schillergässchen 3, D-07743 Jena (Germany); Henning, T., E-mail: tolou.sabri@uni-jena.de [Max Planck Institute for Astronomy Königstuhl 17, D-69117 Heidelberg (Germany)

    2014-01-10

    Amorphous, astrophysically relevant silicates were prepared by laser ablation of siliceous targets and subsequent quenching of the evaporated atoms and clusters in a helium/oxygen gas atmosphere. The described gas-phase condensation method can be used to synthesize homogeneous and astrophysically relevant silicates with different compositions ranging from nonstoichiometric magnesium iron silicates to pyroxene- and olivine-type stoichiometry. Analytical tools have been used to characterize the morphology, composition, and spectral properties of the condensates. The nanometer-sized silicate condensates represent a new family of cosmic dust analogs that can generally be used for laboratory studies of cosmic processes related to condensation, processing, and destruction of cosmic dust in different astrophysical environments. The well-characterized silicates comprising amorphous Mg{sub 2}SiO{sub 4} and Fe{sub 2}SiO{sub 4}, as well as the corresponding crystalline silicates forsterite and fayalite, produced by thermal annealing of the amorphous condensates, have been used as real grain surfaces for H{sub 2} formation experiments. A specifically developed ultra-high vacuum apparatus has been used for the investigation of molecule formation experiments. The results of these molecular formation experiments on differently structured Mg{sub 2}SiO{sub 4} and Fe{sub 2}SiO{sub 4} described in this paper will be the topic of the next paper of this series.

  4. Processes forming Gas, Tar, and Coke in Cellulose Gasification from Gas-Phase Reactions of Levoglucosan as Intermediate.

    PubMed

    Fukutome, Asuka; Kawamoto, Haruo; Saka, Shiro

    2015-07-01

    The gas-phase pyrolysis of levoglucosan (LG), the major intermediate species during cellulose gasification, was studied experimentally over the temperature range of 400-900?°C. Gaseous LG did not produce any dehydration products, which include coke, furans, and aromatic substances, although these are characteristic products of the pyrolysis of molten LG. Alternatively, at >500?°C, gaseous LG produced only fragmentation products, such as noncondensable gases and condensable C1 -C3 fragments, as intermediates during noncondensable gas formation. Therefore, it was determined that secondary reactions of gaseous LG can result in the clean (tar- and coke-free) gasification of cellulose. Cooling of the remaining LG in the gas phase caused coke formation by the transition of the LG to the molten state. The molecular mechanisms that govern the gas- and molten-phase reactions of LG are discussed in terms of the acid catalyst effect of intermolecular hydrogen bonding to promote the molten-phase dehydration reactions. PMID:26099988

  5. Functional Identification of the General Acid and Base in the Dehydration Step of Indole-3-glycerol Phosphate Synthase Catalysis*

    PubMed Central

    Zaccardi, Margot J.; Yezdimer, Eric M.; Boehr, David D.

    2013-01-01

    The tryptophan biosynthetic enzyme indole-3-glycerol phosphate synthase is a proposed target for new antimicrobials and is a favored starting framework in enzyme engineering studies. Forty years ago, Parry proposed that the enzyme mechanism proceeds through two intermediates in a series of condensation, decarboxylation, and dehydration steps. X-ray crystal structures have suggested that Lys-110 (numbering according to the Sulfolobus solfataricus enzyme) behaves as a general acid both in the condensation and dehydration steps, but did not reveal an efficient pathway for the reprotonation of this critical residue. Our mutagenesis and kinetic experiments suggest an alternative mechanism whereby Lys-110 acts as a general acid in the condensation step, but another invariant residue, Lys-53, acts as the general acid in the dehydration step. These studies also indicate that the conserved residue Glu-51 acts as the general base in the dehydration step. The revised mechanism effectively divides the active site into discrete regions where the catalytic surfaces containing Lys-110 and Lys-53/Glu-51 catalyze the ring closure (i.e. condensation and decarboxylation) and dehydration steps, respectively. These results can be leveraged toward the development of novel inhibitors against this validated antimicrobial target and toward the rational engineering of the enzyme to produce indole derivatives that are highly prized by the pharmaceutical and agricultural industries. PMID:23900843

  6. Transport-induced shifts in condensate dew-point and composition in multicomponent systems with chemical reaction

    NASA Technical Reports Server (NTRS)

    Rosner, D. E.; Nagarajan, R.

    1985-01-01

    Partial heterogeneous condensation phenomena in multicomponent reacting systems are analyzed taking into consideration the chemical element transport phenomena. It is demonstrated that the dew-point surface temperature in chemically reactive systems is not a purely thermodynamic quantity, but is influenced by the multicomponent diffusion and Soret-mass diffusion phenomena. Several distinct dew-points are shown to exist in such systems and, as a result of transport constraints, the 'sharp' locus between two chemically distinct condensates is systematically moved to a difference mainstream composition.

  7. Production of conjugated linoleic acids through KOH-catalyzed dehydration of ricinoleic acid.

    PubMed

    Yang, Lin; Huang, Yu; Wang, Han Qing; Chen, Zhen-Yu

    2002-10-01

    Production of conjugated linoleic acids (CLA) using castor oil as starting material involves conversion of ricinoleic acid to methyl 12-mesyloxy-octadec-9-enoate (MMOE) followed by dehydration. This process usually uses 1,8-diazabicyclo-(5.4.0)-undec-7-ene (DBU) as an expensive dehydrating reagent. The present study reports that potassium hydroxide (KOH) can serve as a dehydrating reagent in replacement of DBU. The results showed that conversion of MMOE to CLA catalyzed by KOH was an efficient reaction, with a 77% conversion efficiency at 80 degrees C. The CLA isomeric profile produced in KOH-catalyzed dehydration reaction was similar to that catalyzed by DBU. The CLA mixture produced in KOH-catalyzed dehydration of MMOE at 80 degrees C contained 72% 9c,11t-18:2 and 26% 9c,11c-18:2 while in that catalyzed by DBU, 9c,11t-18:2 and 9c,11c-18:2 accounted for 78 and 16%, respectively. It was found that the temperature of dehydration was an important factor in the determination of CLA isomer composition and yield of conversion. Elevating the temperature from 78 to 180 degrees C decreased not only the conversion efficiency but also production of total c,t-18:2 and c,c-18:2 isomers regardless of dehydration catalyzed by either DBU or KOH. It is concluded that KOH may replace DBU as a dehydrating reagent in conversion of MMOE to CLA when the reaction conditions are optimized. PMID:12270670

  8. Dehydration of plutonium trichloride hydrate

    SciTech Connect

    Foropoulos, J. Jr.; Avens, L.R.; Trujillo, E.A.

    1991-12-31

    A process of preparing anhydrous actinide metal trichlorides of plutonium or neptunium by reacting an aqueous solution of an actinide metal trichloride selected from the group consisting of plutonium trichloride or neptunium trichloride with a reducing agent capable of converting the actinide metal from an oxidation state of +4 to +3 in a resultant solution, evaporating essentially all the solvent from the resultant solution to yield an actinide trichloride hydrate material, dehydrating the actinide trichloride hydrate material by heating the material in admixture with excess thionyl chloride, and recovering anhydrous actinide trichloride is provided.

  9. Dehydration

    MedlinePLUS

    ... too much, for example, from exercising in hot weather Fever Vomiting or diarrhea Urinating too much (uncontrolled ... when you are well. Drink more when the weather is hot or you are exercising. If anyone ...

  10. Mechanism of Brønsted acid-catalyzed glucose dehydration.

    PubMed

    Yang, Liu; Tsilomelekis, George; Caratzoulas, Stavros; Vlachos, Dionisios G

    2015-04-24

    We present the first DFT-based microkinetic model for the Brønsted acid-catalyzed conversion of glucose to 5-hydroxylmethylfurfural (HMF), levulinic acid (LA), and formic acid (FA) and perform kinetic and isotopic tracing NMR spectroscopy mainly at low conversions. We reveal that glucose dehydrates through a cyclic path. Our modeling results are in excellent agreement with kinetic data and indicate that the rate-limiting step is the first dehydration of protonated glucose and that the majority of glucose is consumed through the HMF intermediate. We introduce a combination of 1)?automatic mechanism generation with isotopic tracing experiments and 2)?elementary reaction flux analysis of important paths with NMR spectroscopy and kinetic experiments to assess mechanisms. We find that the excess formic acid, which appears at high temperatures and glucose conversions, originates from retro-aldol chemistry that involves the C6 carbon atom of glucose. PMID:25572774

  11. Dehydration Comes on Fast and Can Be Fatal

    MedlinePLUS

    Dehydration comes on fast and can be fatal During the hot summer months,the nation’s emergency physicians ... at a higher risk ofbecoming dehydrated. Causes of Dehydration: Excessive sweating (from heat and/or exercise) with ...

  12. Condensed-phase, halogen-bonded CF3I and C2F5I adducts for perfluoroalkylation reactions.

    PubMed

    Sladojevich, Filippo; McNeill, Eric; Börgel, Jonas; Zheng, Shao-Liang; Ritter, Tobias

    2015-03-16

    A family of practical, liquid trifluoromethylation and pentafluoroethylation reagents is described. We show how halogen bonding can be used to obtain easily handled liquid reagents from gaseous CF3I and CF3CF2I. The synthetic utility of the new reagents is exemplified by a novel direct arene trifluoromethylation reaction as well as adaptations of other perfluoroalkylation reactions. PMID:25651531

  13. Seasonal and Regional Variability of Stratospheric Dehydration 

    E-print Network

    Christenberry, Aaron Joseph

    2012-07-16

    SEASONAL AND REGIONAL VARIABILITY OF STRATOSPHERIC DEHYDRATION A Thesis by AARON JOSEPH CHRISTENBERRY Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE May 2012 Major Subject: Atmospheric Sciences Seasonal and Regional Variability of Stratospheric Dehydration Copyright 2012 Aaron Joseph Christenberry...

  14. Bifunctional building blocks in the Ugi-azide condensation reaction: a general strategy toward exploration of new molecular diversity.

    PubMed

    Gunawan, Steven; Hulme, Christopher

    2013-09-28

    1,5-Disubstituted tetrazoles are an important drug-like scaffold known for their ability to mimic the cis-amide bond conformation. The scaffold is readily accessible via substitution of the carboxylic acid component of the Ugi multi-component reaction (MCR) with TMSN3 in what is herein denoted the Ugi-azide reaction. This full paper presents a concise, novel, general strategy to access a plethora of new heterocylic scaffolds utilizing tethered aldo/keto-acids/esters in the Ugi-azide reaction followed by a ring closing event that generates novel highly complex bis-heterocyclic lactam-tetrazoles. PMID:23912086

  15. Slab crustal dehydration, melting and dynamics through time

    NASA Astrophysics Data System (ADS)

    van Hunen, Jeroen; Bouilhol, Pierre; Magni, Valentina; Maunder, Benjamin

    2015-04-01

    Melting subducted mafic crust is commonly assumed to be the main process leading to silicic melts with an adakitic signature, which may form Archaean granitoids and generate early continental crust. Alternatively, melting of the overriding lower mafic crust and near-Moho depth fractional crystallisation of mantle melts can form differentiated magmas with an adakitic signature. Previous work shows how only very young slabs melt through dehydration melting, or depict melting of dry eclogites via water addition from deeper slab dehydration. We quantify subduction dehydration and melting reactions in a warm subduction system using a thermo-mechanical subduction model with a thermodynamic database. We find that even young (hot) slabs dehydrate before reaching their solidus, which suppresses any slab dehydration melting and creates significant amounts of mantle wedge melting irrespective of slab age. Significant slab crust melting is only achieved in young slabs via water present melting if metamorphic fluids from the subducted mantle flux through the dry eclogites. These slab melts, however, are affected by massive mantle wedge melting and unlikely to participate in the overriding plate felsic magmatism, unlike the shallower, primitive mantle wedge melts. Understanding the overall flux of water carried by the descending slab mantle is therefore of prime importance. We thus inverstigated the deeper dehydration processes in subduction zones and implications for the water cycle throughout Earth's history. We estimate that presently ~26% of the global influx water is recycled into the mantle, and that deep water recycling was also significant (although less efficient, 2-13% at 2.8 Ga) in early Earth conditions, which has important implications for mantle dynamics and tectonic processes in the Early Earth. Alternatively, delamination and underplating of the mafic subducted crust would be a suitable mechanism to fit the geological record. We thus explore the conditions for which this may happen, and found that for a wide range of ages, the uppermost part of the subducted slab might delaminate to form compositionally buoyant plumes that rise through the mantle wedge. Thick crust on young slabs (as perhaps representative for a hotter, early Earth) may delaminate entirely and reside in the mantle wedge. Under such conditions, this ponded crust might melts subsequently, forming "adakitic" felsic melts contributing to a significant amount of the overriding plate crustal volumes.

  16. Preparation of neuroprotective condensed 1,4-benzoxazepines by regio- and diastereoselective domino Knoevenagel–[1,5]-hydride shift cyclization reaction

    PubMed Central

    Tóth, László; Fu, Yan; Zhang, Hai Yan; Mándi, Attila; Kövér, Katalin E; Illyés, Tünde-Zita; Kiss-Szikszai, Attila; Balogh, Balázs; Kurtán, Tibor

    2014-01-01

    Summary Condensed O,N-heterocycles containing tetrahydro-1,4-benzoxazepine and tetrahydroquinoline moieties were prepared by a regio- and diastereoselective domino Knoevenagel–[1,5]-hydride shift cyclization reaction of a 4-aryl-2-phenyl-1,4-benzoxazepine derivative obtained from flavanone. The relative configuration of products were determined by the correlation of 3 J H,H coupling data with the geometry of major conformers accessed by DFT conformational analysis. Separated enantiomers of the products were characterized by HPLC-ECD data, which allowed their configurational assignment on the basis of TDDFT-ECD calculation of the solution conformers. Two compounds showed neuroprotective activities against hydrogen peroxide (H2O2) or ?-amyloid25–35 (A?25–35)-induced cellular injuries in human neuroblastoma SH-SY5Y cells in the range of those of positive controls. PMID:25550721

  17. Method for thermal dehydration of brown coal

    SciTech Connect

    Kakunai, H.; Motonaga, K.; Nada, J.; Nakako, Y.; Ohzawa, T.; Yokota, S.

    1980-01-29

    A method is disclosed for thermal dehydration of brown coal, by which an excellent heat recovery can be accomplished. The method includes the steps of admixing raw brown coal with a solvent to prepare a slurry, preheating the slurry in a heat exchanger, heating the same at 100 to 300/sup 0/C, passing it through a gasliquid separator to separate it into a steam-containing vapor and a dehydrated slurry and recoverying the dehydrated slurry while the steam-containing vapor is recycled to the heat exchanger so as to be utilized as a heating medium for preheating the slurry.

  18. Dehydration Processes of Sugar Glasses and Crystals

    NASA Astrophysics Data System (ADS)

    Seo, Jeong-Ah; Kwon, Hyun-Joung; Kim, Hyung Kook; Hwang, Yoon-Hwae

    2006-05-01

    The dehydration processes of sugar glasses and sugar crystals were studied by using Thermogravimetry — Differential Thermal Analysis method. We used three monosaccharide sugars (fructose, galactose, and glucose) and three disaccharide sugars (sucrose, maltose and trehalose). It was found that a trehalose showed different dehydration process compared to the other sugars. The amount of mass reductions in sugar glasses is larger than that in sugar crystals. However, in the case of trehalose, the amount of mass reduction in trehalose glasses is smaller than that in trehalose crystals. It seems to be possible that this unique dehydration property of trehalose glasses maybe relate to the cell protection ability during an anhydrobiosis process.

  19. Linked strategy for the production of fuels via formose reaction.

    PubMed

    Deng, Jin; Pan, Tao; Xu, Qing; Chen, Meng-Yuan; Zhang, Ying; Guo, Qing-Xiang; Fu, Yao

    2013-01-01

    Formose reaction converts formaldehyde to carbohydrates. We found that formose reaction can be used linking the biomass gasification with the aqueous-phase processing (APP) to produce liquid transportation fuel in three steps. First, formaldehyde from syn-gas was converted to triose. This was followed by aldol condensation and dehydration to 4-hydroxymethylfurfural (4-HMF). Finally, 4-HMF was hydrogenated to produce 2,4-dimethylfuran (2,4-DMF) or C(9)-C(15) branched-chain alkanes as liquid transportation fuels. In the linked strategy, high energy-consuming pretreatment as well as expensive and polluting hydrolysis of biomass were omitted, but the high energy recovery of APP was inherited. In addition, the hexoketoses via formose reaction could be converted to HMFs directly without isomerization. A potential platform molecule 4-HMF was formed simultaneously in APP. PMID:23393625

  20. Condensed Matter Cluster Reactions in LENR Power Cells for a Radical New Type of Space Power Source

    Microsoft Academic Search

    Xiaoling Yang; George H. Miley; Heinz Hora

    2009-01-01

    This paper reviews previous theoretical and experimental study on the possibility of nuclear events in multilayer thin film electrodes (Lipson &etal;, 2004 and 2005; Miley &etal;, 2007), including the correlation between excess heat and transmutations (Miley and Shrestha, 2003) and the cluster theory that predicts it. As a result of this added understanding of cluster reactions, a new class of

  1. One-pot three component condensation reaction in water: an efficient and improved procedure for the synthesis of furo[2,3- d]pyrimidine-2,4(1 H,3 H)-diones

    Microsoft Academic Search

    Ahmad Shaabani; Mohammad Bagher Teimouri; Hamid Reza Bijanzadeh

    2002-01-01

    The environment-friendly three component condensation reactions of N,N?-dimethylbarbituric acid, 4-nitrobenzaldehyde and alkyl or aryl isocyanides to afford the corresponding furo[2,3-d]pyrimidine-2,4(1H,3H)-diones, in water, in high yields after several minutes are reported.

  2. Iron Oxide-Supported Copper Oxide Nanoparticles (Nanocat-Fe-CuO): Magnetically Recyclable Catalysts for the Synthesis of Pyrazole Derivatives, 4-Methoxyaniline, and Ullmann-type Condensation Reactions

    EPA Science Inventory

    An efficient and benign protocol is reported for the synthesis of 4-methoxyaniline, medicinally important pyrazole derivatives, and Ullmann-type condensation reaction using magnetically separable and reusable magnetite-supported copper (nanocat-Fe-CuO) nanoparticles under mild co...

  3. Neuropsychological Performance, Postural Stability, and Symptoms After Dehydration

    Microsoft Academic Search

    Akshay V. Patel; Jason P. Mihalik; Andrew J. Notebaert; Kevin M. Guskiewicz; William E. Prentice

    Context: Dehydration and concussion are common in athletic performance. Some experts have speculated that dehydration may negatively influence performance on tests commonly used for concussion assessment. Objective: To determine how the signs and symptoms, neu- ropsychological performance, and postural stability are affected by dehydration. Design: Repeated-measures design assessing subjects in the euhydrated and dehydrated conditions. Setting: Sports Medicine Research Laboratory.

  4. Process conditions effect on the quality of banana osmotically dehydrated

    Microsoft Academic Search

    L. Atares; M. J. Sousa Gallagher; F. A. R. Oliveira

    2011-01-01

    Banana is greatly perishable and does not resist freezing, hence dehydration is the preservation technique of choice. This paper deals with the effect of process conditions on both the dehydration kinetics and the final quality of banana osmotically dehydrated. Banana slices (5mm thick, 23mm diameter) were osmotically dehydrated for 4h, following a 32 full factorial design (temperature (30, 40, and

  5. Concise Access to 2-Aroylbenzothiazoles by Redox Condensation Reaction between o-Halonitrobenzenes, Acetophenones, and Elemental Sulfur.

    PubMed

    Nguyen, Thanh Binh; Pasturaud, Karine; Ermolenko, Ludmila; Al-Mourabit, Ali

    2015-05-15

    A wide range of 2-aroylbenzothiazoles 3 including some pharmacologically relevant derivatives can be obtained in high yields by simply heating o-halonitrobenzenes 1, acetophenones 2, elemental sulfur, and N-methylmorpholine. This three-component nitro methyl coupling was found to occur in an excellent atom-, step-, and redox-efficient manner in which elemental sulfur played the role of nucleophile building block and redox moderating agent to fulfill electronic requirements of the global reaction. PMID:25929738

  6. Dehydration processes using membranes with hydrophobic coating

    DOEpatents

    Huang, Yu; Baker, Richard W; Aldajani, Tiem; Ly, Jennifer

    2013-07-30

    Processes for removing water from organic compounds, especially polar compounds such as alcohols. The processes include a membrane-based dehydration step, using a membrane that has a dioxole-based polymer selective layer or the like and a hydrophilic selective layer, and can operate even when the stream to be treated has a high water content, such as 10 wt % or more. The processes are particularly useful for dehydrating ethanol.

  7. Synthesis of pyrazole containing ?-amino acids via a highly regioselective condensation/aza-Michael reaction of ?-aryl ?,?-unsaturated ketones.

    PubMed

    Gilfillan, Lynne; Artschwager, Raik; Harkiss, Alexander H; Liskamp, Rob M J; Sutherland, Andrew

    2015-04-21

    A synthetic approach for the preparation of a new class of highly conjugated unnatural ?-amino acids bearing a 5-arylpyrazole side-chain has been developed. Horner-Wadsworth-Emmons reaction of an aspartic acid derived ?-keto phosphonate ester with a range of aromatic aldehydes gave ?-aryl ?,?-unsaturated ketones. Treatment of these with phenyl hydrazine followed by oxidation allowed the regioselective synthesis of pyrazole derived ?-amino acids. As well as evaluating the fluorescent properties of the ?-amino acids, their synthetic utility was also explored with the preparation of a sulfonyl fluoride derivative, a potential probe for serine proteases. PMID:25774874

  8. Condensed Matter Cluster Reactions in LENR Power Cells for a Radical New Type of Space Power Source

    NASA Astrophysics Data System (ADS)

    Yang, Xiaoling; Miley, George H.; Hora, Heinz

    2009-03-01

    This paper reviews previous theoretical and experimental study on the possibility of nuclear events in multilayer thin film electrodes (Lipson et al., 2004 and 2005; Miley et al., 2007), including the correlation between excess heat and transmutations (Miley and Shrestha, 2003) and the cluster theory that predicts it. As a result of this added understanding of cluster reactions, a new class of electrodes is under development at the University of Illinois. These electrodes are designed to enhance cluster formation and subsequent reactions. Two approaches are under development. The first employs improved loading-unloading techniques, intending to obtain a higher volumetric density of sites favoring cluster formation. The second is designed to create nanostructures on the electrode where the cluster state is formed by electroless deposition of palladium on nickel micro structures. Power units employing these electrodes should offer unique advantages for space applications. This is a fundamental new nuclear energy source that is environmentally compatible with a minimum of radiation involvement, high specific power, very long lifetime, and scalable from micro power to kilowatts.

  9. Condensed Matter Cluster Reactions in LENR Power Cells for a Radical New Type of Space Power Source

    SciTech Connect

    Yang Xiaoling; Miley, George H.; Hora, Heinz [University of Illinois Urbana-Champaign, NPL Associates, Urbana, IL 217-333-3772 (United States); Department of Theoretical Physics Univ. of New South Wales Sydney (Australia)

    2009-03-16

    This paper reviews previous theoretical and experimental study on the possibility of nuclear events in multilayer thin film electrodes (Lipson et al., 2004 and 2005; Miley et al., 2007), including the correlation between excess heat and transmutations (Miley and Shrestha, 2003) and the cluster theory that predicts it. As a result of this added understanding of cluster reactions, a new class of electrodes is under development at the University of Illinois. These electrodes are designed to enhance cluster formation and subsequent reactions. Two approaches are under development. The first employs improved loading-unloading techniques, intending to obtain a higher volumetric density of sites favoring cluster formation. The second is designed to create nanostructures on the electrode where the cluster state is formed by electroless deposition of palladium on nickel micro structures. Power units employing these electrodes should offer unique advantages for space applications. This is a fundamental new nuclear energy source that is environmentally compatible with a minimum of radiation involvement, high specific power, very long lifetime, and scalable from micro power to kilowatts.

  10. From porosity formation to permeability generation and the initiation of flow in dehydrating rocks

    NASA Astrophysics Data System (ADS)

    John, Timm; Podladchikov, Yuri; Plümper, Oliver; Vrijmoed, Hans; Scambelluri, Marco

    2015-04-01

    Water escape from dehydrating rocks within the Earth's interior is a key process for long-term global water and element cycles. Existing fluid flow models require a priori physical assumptions (e.g., preexisting porosity) and cannot resolve the evolution from initial fluid production to flow channelization. In order to develop a model for this evolution, we need to unravel natural laboratories that display the incipient dehydration stages and the micro- to macro-scale fluid escape route evolution. The Erro-Tobbio meta-serpentinites (Italy) provide a unique snapshot into these early dehydration stages, recording the breakdown of hydrous antigorite to anhydrous olivine plus fluid and the formation of an olivine-vein network. We find that dehydration, fluid pooling, and flow initiation are controlled by micro-scale compositional rock differences. Our model starts with a rock in which all water is stored in solid and any preexisting porosity is negligible (zero-porosity case). Increasing temperature will initiate dehydration reactions, dividing the rock continuously into a dry solid and a fluid-filled porosity. Spatially variable reaction progress results in dynamically evolving porosity/permeability and heterogeneous fluid-pore pressure distributions. Fluid-pressure gradient relaxation causes fluid flow and its thermodynamic feedback triggers reactions to progress, resulting in a self-amplifying process. Our new thermodynamic-mechanical model for reaction-porosity waves shows that fluid flow occurs solely in the reaction products and self-organizes into channelized fluid escape networks. This holds the key to formulating future quantitative models that address spatiotemporal processes such as the coupling between local fluid production and regional to global scale fluxes of elements.

  11. Serpentine Rheology and Dehydration at High-Pressure, Implications for Intermediate-depth Seismicity

    NASA Astrophysics Data System (ADS)

    Hilairet, N.; Reynard, B.; Wang, Y.; Daniel, I.

    2007-12-01

    Serpentinites have a lower viscosity than other mantle and slab materials within subduction zones. Serpentine dehydration is believed to play a major role in intermediate-depth seismicity, and several mechanisms have been proposed such as dehydration embrittlement and shear heating. However, quantifying the influence of serpentine rheology and its dehydration on strain rates and stress distribution within subduction zones has remained beyond reach, because of the lack of experimental data on deformation of the high-pressure variety antigorite, at relevant P and T conditions. Antigorite deformation experiments were carried out both within its stability field and during dehydration, over a pressure temperature (P-T) range of 1 - 4 GPa and 200-600 /deg C, at strain rates between ~10-4 and 10-6 s-1, in a D-DIA apparatus at GSE-CARS (Advanced Photo Source). Strain rates and stresses were obtained respectively from in-situ monitoring the sample length with X-ray radiographs, and azimuthal dependence of d- spacings on diffraction patterns. The determined stress-strain curves within antigorite stability field were fitted to a power-law equation including both temperature and pressure dependence. At the lowest strain rate investigated and nominal T within the antigorite stability field, localization occurred accompanied by local dehydration and a moderate increase in strain rate. Whatever the reaction and the sign of the volume change, dehydration induced an increase in strain rate. The present results show that antigorite rheology is likely to govern stress building-up and relaxation at the slab surface during interseismic time. We will discuss the implications of the results from the dehydration experiments for the role of serpentinites in intermediate-depth seismicity within subduction zones.

  12. Bulk Effect Of Local Non-Hydrostatic Stresses On The Dehydration And Permeability Characteristics Of Gypsum: Experimental Approach

    NASA Astrophysics Data System (ADS)

    Llana Funez, S.; Faulkner, D. R.; Wheeler, J.

    2009-12-01

    Dehydrations reactions are very significant in some deep geodynamic settings because the release of fluid phase under confined conditions and limited porosity may produce fluid overpressure and ultimately mechanical embrittlement if the rocks are subject to tectonic stresses. This is thought to be a triggering mechanism for seismicity in tectonically active zones, like subduction zones. Thus, the balance between thermodynamics and physical parameters inherent to natural rock materials at high-pressure conditions is therefore of importance in these tectonic settings to understand how this seismicity results. Metamorphic reactions are in the first instance controlled by thermodynamics, but the progress of the reaction may be determined by other independent physical parameters such as permeability. We have studied experimentally the dehydration reaction in Volterra gypsum, for application to the mechanics of fold and thrust belts and also as an analogue of similar reactions in subduction zones, by controlling confining pressure, pore fluid pressure and temperature. We also measured permeability throughout the progress of the reaction. We have sampled the temperature dependence of the reaction but, unlike previous work that has only considered conditions where confining pressure equals pore pressure, we have also investigated the effect of a reduction of pore fluid pressure in the progress and development of the dehydration reaction. We found that changes in the pore fluid pressure have a much greater effect on the reaction rate than changes in confining pressure. The permeability increases rapidly very early in the dehydration history, suggesting that only a small amount of reaction produces an interconnected pore network from an initially very low permeability rock. Our results imply that low porosity, low permeability rocks such Volterra gypsum will only have limited capacity to evacuate fluids evolved from the dehydration in reacting areas very early in the reaction progress.

  13. Dehydration kinetics of talc at 1 bar

    NASA Technical Reports Server (NTRS)

    Ganguly, J.; Bose, K.

    1991-01-01

    Experimental results on the dehydration kinetics of talc, which is likely to be a major potential resource for water and hydrogen in carbonaceous chondrites, is presented. The rate of dehydration of an essentially pure Mg-end member natural talc, (Mg(.99)Fe(.01))3Si4O10(OH)2, was studied by measuring in situ weight change under isothermal condition at 1 bar as a function of time in the temperature range 775 to 985 C. The grain size of the starting material was 0.7 to 1 micron. It was found that the data up to 50 to 60 percent dehydration can be fitted by an equation of the form alpha = exp(-Kt(exp n)), where alpha is the weight fraction of talc remaining, K is a rate constant and n is a numerical constant for a given temperature. For any set of isothermal data, there is a major change in the value of n for larger dehydration. For up to approximately 50 percent dehydration, all rate constants can be described by an Arrheniun relation with an activation energy of 432 (+/- 30) kJ/mol; n has a nearly constant value of 0.54 between 775 and 875 C, but increases almost linearly according to n = -10.77 + 0.012T C at T greater than or equal to 875 C.

  14. Geothermal demonstration: Zunil food dehydration facility

    SciTech Connect

    Maldonado, O. (Consultecnia, Guatemala City (Guatemala)); Altseimer, J.; Thayer, G.R. (Los Alamos National Lab., NM (United States)); Cooper, L. (Energy Associates International, Albuquerque, NM (United States)); Caicedo, A. (Unidad de Desarrollo Geotermico, Guatemala City (Guatemala). Inst. Nacional de Electrificacion)

    1991-08-01

    A food dehydration facility was constructed near the town of Zunil, Guatemala, to demonstrate the use of geothermal energy for industrial applications. The facility, with some modifications to the design, was found to work quite satisfactorily. Tests using five different products were completed during the time geothermal energy was used in the plant. During the time the plant was not able to use geothermal energy, a temporary diesel-fueled boiler provided the energy to test dehydration on seven other crops available in this area. The system demonstrates that geothermal heat can be used successfully for dehydrating food products. Many other industrial applications of geothermal energy could be considered for Zunil since a considerable amount of moderate-temperature heat will become available when the planned geothermal electrical facility is constructed there. 6 refs., 15 figs., 7 tabs.

  15. Amine catalyzed condensation of tetraethylorthosilicate

    NASA Technical Reports Server (NTRS)

    Jones, S.

    2001-01-01

    The catalysis of the condensation of hydrolyzed metal alkoxides by amines has been mentioned in the literature, but there has been no systematic study of their influence on the rate of the condensation reaction of the alkoxide and the microstructure of the resultant gel.

  16. 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD) an efficient homogeneous catalyst for aldol condensation reactions. Study of the catalyst recovery and reusability using CO 2

    Microsoft Academic Search

    Iuliana Cota; Francisco Medina; Jesús E. Sueiras; Didier Tichit

    2011-01-01

    In this work it was shown that TBD (1,5,7-triazabicyclo[4.4.0]dec-5-ene), a cheap and commercially available guanidine base, efficiently catalyzes aldol condensation reactions yielding interesting products for pharmacological and fragrance industries. This methodology works under solvent-less conditions and affords with very good conversions the corresponding products. Moreover, a simple and effective separation protocol using the CO2 fixation was employed. The catalyst could

  17. ADVANCED DEHYDRATOR DESIGN SAVES GAS AND REDUCES HAP EMISSIONS

    EPA Science Inventory

    Glycol dehydrators remove water from gas pipe lines. An advanced dehydrator by Engineered Concepts, Farmington, NM, saves a significant amount of gas, while reducing hazardous air pollutants, volatile organic compounds and CO2 air pollutants...

  18. Acid-catalysed glucose dehydration in the gas phase: a mass spectrometric approach.

    PubMed

    Ricci, Andreina; Di Rienzo, Brunella; Pepi, Federico; Troiani, Anna; Garzoli, Stefania; Giacomello, Pierluigi

    2015-01-01

    Understanding on a molecular level the acid-catalysed decomposition of the sugar monomers from hemicellulose and cellulose (e.g.?glucose, xylose), the main constituent of lignocellulosic biomass is very important to increase selectivity and reaction yields in solution, key steps for the development of a sustainable renewable industry. In this work we reported a gas-phase study performed by electrospray triple quadrupole mass spectrometry on the dehydration mechanism of D-glucose. In the gas phase, reactant ions corresponding to protonated D-glucose were obtained in the ESI source and were allowed to undergo collisionally activated decomposition (CAD) into the quadrupole collision cell. The CAD mass spectrum of protonated D-glucose is characterized by the presence of ionic dehydrated daughter ion (ionic intermediates and products), which were structurally characterized by their fragmentation patterns. In the gas phase D-glucose dehydration does not lead to the formation of protonated 5-hydroxymethyl-2-furaldehyde, but to a mixed population of m/z 127 isomeric ions. To elucidate the D-glucose dehydration mechanism, 3-O-methyl-D-glucose was also submitted to the mass spectrometric study; the results suggest that the C3 hydroxyl group plays a key role in the reaction mechanism. Furthermore, protonated levulinic acid was found to be formed from the monodehydrated D-glucose ionic intermediate, an alternative pathway other than the known route consisting of 5-hydroxymethyl-2-furaldehyde double hydration. PMID:25601697

  19. Water, water everywhere: dehydration in the elderly.

    PubMed

    Sacks, Gordon S; Martin, Caren McHenry

    2005-11-01

    Dehydration is a common disorder in the frail elderly patient. Understanding the mechanisms by which fluid and electrolyte abnormalities occur, as well as the implications of specific laboratory values, is key to providing optimal diagnosis and treatment. Management of fluid abnormalities relies on gradual rehydration with the proper fluids to restore both fluid and electrolytes. PMID:16548671

  20. DRYING OF OSMOTICALLY DEHYDRATED BIOLOGICAL MATERIALS

    Microsoft Academic Search

    STEFAN JAN KOWALSKI; DOMINIK MIERZWA

    The paper concerns convective and microwave drying of biological materials (vegetables) with osmotic dehydration as a pretreatment process. The main aim of the studies was to work out efficient conditions of such a combined drying and to determine the amount of water which can be removed from the vegetables by immer- sion in the hypertonic aqueous solutions of sucrose and

  1. Geothermal demonstration: Zunil food dehydration facility

    Microsoft Academic Search

    O. Maldonado; J. Altseimer; G. R. Thayer; L. Cooper; A. Caicedo

    1991-01-01

    A food dehydration facility was constructed near the town of Zunil, Guatemala, to demonstrate the use of geothermal energy for industrial applications. The facility, with some modifications to the design, was found to work quite satisfactorily. Tests using five different products were completed during the time geothermal energy was used in the plant. During the time the plant was not

  2. Hybrid Quantum Mechanics/Molecular Mechanics-Based Molecular Dynamics Simulation of Acid-Catalyzed Dehydration of Polyols in Liquid Water

    SciTech Connect

    Caratzoulas, Stavros [Catalysis Center for Energy Innovation, Univ. of Delaware, Newark, DE (United States); Courtney, Timothy [Univ. of Delaware, Newark, DE (United States); Vlachos, Dionisios G. [Catalysis Center for Energy Innovation, Univ. of Delaware, Newark, DE (United States)

    2011-08-18

    We use the conversion of protonated glycerol to acrolein for a case study of the mechanism of acid-catalyzed dehydration of polyols in aqueous environments. We employ hybrid Quamtum Mechanics/Molecular Mechanics Molecular Dynamics (QM/MM MD) simulations with biased sampling and perform free energy calculations for the elementary steps of the reaction. We investigate the effects of solvent dynamics and in particular the role of quantum mechanical water in the dehydration mechanism. We present results supporting a mechanism that proceeds via water-mediated proton transfers and thus through an enol intermediate. We find that the first dehydration may take place by two, low-energy pathways requiring, respectively, 20.9 and 18.8 kcal/mol of activation free energy. The second dehydration requires 19.9 kcal/mol of activation free energy while for the overall reaction we compute a free energy change of ?8 kcal/mol.

  3. Effects of catalyst pore structure and acid properties on the dehydration of glycerol.

    PubMed

    Choi, Youngbo; Park, Hongseok; Yun, Yang Sik; Yi, Jongheop

    2015-03-01

    Hierarchical porous catalysts have recently attracted increasing interest because of the enhanced accessibility to active sites on such materials. In this context, previously reported hierarchically mesoporous ASN and ASPN materials are evaluated by applying them to the dehydration of glycerol, and demonstrate excellent catalytic performance. In addition, a comprehensive understanding of the effects of pore structures and the acid properties on the reaction through comparative studies with microporous HZSM-5 and mesoporous AlMCM-41 is provided. PMID:25418679

  4. Dimer acid esters by simultaneous dehydration and polymerization of technical methyl ricinoleate

    Microsoft Academic Search

    G. Silverstone

    1967-01-01

    Filtrol 13 may be used to dehydrate methyl ricinoleate with simultaneous dimerization and polymerization of the linoleate\\u000a esters formed. Hydrolysis of the ester group is avoided by the use of xylene as an azeotroping solvent and the preferred method\\u000a of reaction is the dropwise addition of the ester to a stirred suspension of catalyst in xylene. Products prepared by this

  5. Catalytic dehydration of propylene glycol with salts in near-critical water

    Microsoft Academic Search

    Ziyue Dai; Bunpei Hatano; Hideyuki Tagaya

    2004-01-01

    We carried out the dehydration of propylene glycol in near-critical water to study the reactivity of diol under high temperature and pressure. The end product, 2-methyl-2-pentenal (MP), was identified by GS-MS. The yield of MP was 1.8wt.% in pure water at 300°C for 120min. As the catalyst, zinc chloride (ZnCl2) and sodium carbonate (Na2CO3) were added in the reaction mixture

  6. Solar energy storage using reversible hydration-dehydration of CaO-Ca\\/OH\\/2

    Microsoft Academic Search

    J. K. Rosemary; G. L. Bauerle; T. H. Springer

    1979-01-01

    Studies of solar energy storage by the reversible hydration of CaO-Ca(OH)2 are presented. The properties of CaO-Ca(OH)2 were investigated under conditions typical of a fixed-bed reactor, in which heat required to dehydrate the salt is carried to it by a heat transfer fluid, and heat generated by the reverse reaction is carried away by the same fluid. In cycling tests

  7. Cryoprotective Dehydration: Clues from an Insect

    Microsoft Academic Search

    M. Roger Worland; Gordana Grubor-Lajši?; Jelena Pura?; Michael Thorne; Melody Clark

    \\u000a Arthropods have evolved a number of different adaptations to survive extreme environmental temperatures including, in some\\u000a regions, over-wintering temperatures well below 0°C. One of the less common adaptations to surviving cold is that of cryoprotective\\u000a dehydration, where the animal becomes almost anhydrobiotic with the loss of virtually all osmotically active water. In this\\u000a chapter, we describe integrated studies utilising physiology,

  8. Dehydration transformation in Ca-montmorillonite

    Microsoft Academic Search

    P. Bala; B. K. Samantaray; S. K. Srivastava

    2000-01-01

    The present work deals with the dehydration transformation of Ca-montmorillonite in the temperature range 30°–500°C. Thermal,\\u000a infrared (IR), and X-ray diffraction (XRD) analyses were used to describe the thermal transformation. The microstructural\\u000a and layer disorder parameters like crystallite size, r.m.s. strain (?e2?1\\/2), variation of interlayer spacing (g), and proportion of planes which were affected by the defect (?), have all

  9. Biomass energy analysis for crop dehydration

    SciTech Connect

    Whittier, J.P.; Haase, S.G.; Quinn, M.W.; Zachritz, W.; Lansford, R.; Swanson, D.

    1995-06-01

    In 1994, an agricultural processing facility began constructing a new spice and herb dehydration facility in southern New Mexico. Because of the considerable energy intensity of the dehydration operation, management of energy costs is of special concern to the facility. Biomass energy conversion offers the potential for firms to reduce annual operating costs-especially firms with access to low-cost resources. Because the selected facility produces a biomass by-product as a result of its dehydration operation, it is appropriate to explore the technical, regulatory, institutional and economic conditions that affect the successful utilization of biomass resources. The facility is characterized as a small-scale installation, relative to other energy users. In this context, small-scale represents less than 100 million Btu per hour of thermal load and less than 1 MWe of electrical load. However, the projected annual energy bill is approximately $1.1 million and represents a significant portion of operational costs for the firm. For this study, the biomass resources in southern New Mexico and western Texas are detailed. Annual supplies of various biomass resources (i.e., wood chips, pecan shells, discarded tires and cotton gin trash) were inventoried. Further, delivered costs are projected for each of the resource forms. A technical assessment for the small-scale gasification and combustion systems is presented.

  10. Crude oil dehydrator/desalter control system

    SciTech Connect

    Richter, A.P. Jr.; Tuggle, R.; Clinard, R.H. Jr.; Campsey, R.L.; Lankford, F.L. Jr.

    1986-04-08

    A system is described for controlling the content of an impurity in a crude oil stream consisting of: means for adding a demulsifier to a stream of produced wet crude oil, means for receiving the produced wet crude oil stream with demulsifier for separating produced water and gas from the crude oil to provide a separated crude oil stream, at least one mixing means receiving wash water and the separated crude oil stream for mixing the wash water with the separated crude oil stream in accordance with a control signal to provide a crude oil/wash water stream, means for sensing a pressure drop across the mixing means and providing a pressure drop signal representative thereof, and at least one dehydrator means for removing substantial amounts of water from the crude oil/wash water stream to provide a dehydrated crude oil stream, means for monitoring the content of the impurity in the dehydrated crude oil stream and providing an impurity content signal representative thereof, and control means for providing the control signal in accordance with the impurity content signal and the pressure drop signal so as to control the impurity content of the dry crude oil stream.

  11. Basic Study on Sludge Concentration and Dehydration with Ultrasonic Exposure

    NASA Astrophysics Data System (ADS)

    Sawada, Yuta; Nagashima, Satoshi; Uchida, Takeyoshi; Kawashima, Norimichi; Takeuchi, Shinichi; Akita, Masashi; Nagaoka, Hiroshi

    2005-06-01

    We study the condensation of sludge and the improvement of the dehydration efficiency of sludge by acoustic cavitation for efficiency improvement and cost reduction in water treatment. An ultrasound wave was irradiated into activated sludge in the water tank of our ultrasound exposure system and a standing wave acoustic field was formed using a vibrating disk driven by a Langevin-type transducer. The vibrating disk was mounted on the bottom of the water tank. Acoustic cavitation was generated in the activated sludge suspension and the sludge was floated to the water surface by ultrasound exposure with this system. We observed B-mode ultrasound images of the activated sludge suspension before ultrasound exposure and that of the floated sludge and treated water after ultrasound exposure. The ultrasound diagnostic equipment was used for the observation of the B-mode ultrasound images of the sludge. It was found that the sludge floated to the water surface because of adhesion of microbubbles generated by acoustic cavitation to the sludge particles, which decreased the sludge density. It can be expected that the drifting sludge in water can be recovered by the flotation thickening method of sludge as an application of the results of this study. It is difficult to recover the drifting sludge in water by the conventional gravity thickening method.

  12. A multidisciplinary approach to the study of the plasma membrane of Zea mays pollen during controlled dehydration

    Microsoft Academic Search

    C. Kerhoas; G. Gay; C. Dumas

    1987-01-01

    A multidisciplinary approach (freeze-fracture, nuclear magnetic resonance, differential scanning calorimetry, isoelectric focusing and fluorochromatic reaction test) has been used to follow the behaviour of Zea mays pollen during dehydration - and to estimate its quality. At anthesis, the water content of maize pollen is 57–58% and the vegetative plasma membrane is continous and well structured with a very low density

  13. Investigations on the cause of electrocardiogram changes during dehydration

    E-print Network

    Clark, Donald Ray

    1966-01-01

    OF CONTENTS Chapter I. INTRODUCTION II. LITERATURE CITED Page III. PROCEDURES AND TECHNIQUES IV. RESULTS V. DISCUSSION VI . SUMMARY 17 21 TABLES AND FIGURES REFERENCES 41 LIST OF TABLES Table Page EKG Intervals (Seconds) Before and After... Dehydration. Exp. I Goats . . . . . . . . . . . . . . . . 25 EKG Intervals (Seconds) Before and After Dehydration. Exp. II Goats and Exp. III Dogs 24 III. Standard Limb Lead P Wave Voltages (Millivolts) Before and After Dehydration . 25 IV Standard Limb...

  14. Effects of Dehydration on Fish Muscles at Chilled Temperature

    NASA Astrophysics Data System (ADS)

    Miki, Hidemasa; Seto, Fuminori; Nishimoto, Motomi; Nishimoto, Junichi

    Recently,new method of removing water from fish fillet at low temperature using dehydration sheet have been reported. The present study is concerned with the factors to affect the quality during dehydration of horse mackerel muscle at low temperature. The rate of dehydration at -3 °C was about two times faster than that at 0 °C. The rate of denaturation of fish muscle protein was kept less than about 10 % (ATPase activity) of the undenaturated initial values after removing free water content. Present results suggest the practical possibility of the dehydration at -3 °C for keeping quality of fish flesh.

  15. Modulation of Dehydration Tolerance in Soybean Seedlings (Dehydrin Mat1 Is Induced by Dehydration but Not by Abscisic Acid).

    PubMed Central

    Whitsitt, M. S.; Collins, R. G.; Mullet, J. E.

    1997-01-01

    Germinated soybean (Glycine max L. cv Williams 82) seedlings subjected to rapid dehydration begin to lose the ability to recover when the relative water content of the plant decreases below 60%. The expanded cells of the hypocotyl appear more susceptible to dehydration-induced damage than do cells in the hypocotyl zone of cell growth. Pretreatment of seedlings prior to rapid dehydration with nonlethal water deficit or exogenous abscisic acid (ABA) shifts this viability threshold to progressively lower relative water contents, indicating the acquisition of increased dehydration tolerance. Increased tolerance is associated with osmotic adjustment in the hypocotyl zone of cell growth and with increases in soybean dehydrin Mat1 mRNA levels. The accumulation of Mat1 mRNA is dehydration dependent but insensitive to ABA. Induction of Mat1 mRNA accumulation by dehydration but not by ABA makes it an unusual member of the dehydrin family. PMID:12223753

  16. Intraslab earthquakes: dehydration of the Cascadia slab.

    PubMed

    Preston, Leiph A; Creager, Kenneth C; Crosson, Robert S; Brocher, Thomas M; Trehu, Anne M

    2003-11-14

    We simultaneously invert travel times of refracted and wide-angle reflected waves for three-dimensional compressional-wave velocity structure, earthquake locations, and reflector geometry in northwest Washington state. The reflector, interpreted to be the crust-mantle boundary (Moho) of the subducting Juan de Fuca plate, separates intraslab earthquakes into two groups, permitting a new understanding of the origins of intraslab earthquakes in Cascadia. Earthquakes up-dip of the Moho's 45-kilometer depth contour occur below the reflector, in the subducted oceanic mantle, consistent with serpentinite dehydration; earthquakes located down-dip occur primarily within the subducted crust, consistent with the basalt-to-eclogite transformation. PMID:14615535

  17. Dehydration of plutonium or neptunium trichloride hydrate

    DOEpatents

    Foropoulos, Jr., Jerry (Los Alamos, NM); Avens, Larry R. (Los Alamos, NM); Trujillo, Eddie A. (Espanola, NM)

    1992-01-01

    A process of preparing anhydrous actinide metal trichlorides of plutonium or neptunium by reacting an aqueous solution of an actinide metal trichloride selected from the group consisting of plutonium trichloride or neptunium trichloride with a reducing agent capable of converting the actinide metal from an oxidation state of +4 to +3 in a resultant solution, evaporating essentially all the solvent from the resultant solution to yield an actinide trichloride hydrate material, dehydrating the actinide trichloride hydrate material by heating the material in admixture with excess thionyl chloride, and recovering anhydrous actinide trichloride is provided.

  18. Dehydration and Dehydrogenation of Ethylene Glycol on Rutile TiO2(110)

    SciTech Connect

    Li, Zhenjun; Kay, Bruce D.; Dohnalek, Zdenek

    2013-08-07

    The interactions of ethylene glycol (EG) with partially reduced rutile TiO2(110) surface have been studied using temperature programmed desorption (TPD). The saturation coverage on the surface Ti rows is determined to be 0.43 monolayer (ML), slightly less than one EG per two Ti sites. Most of the adsorbed ethanol (~80%) undergoes further reactions to other products. Two major channels are observed, dehydration yielding ethylene and water and dehydrogenation yielding acetaldehyde and hydrogen. Hydrogen formation is rather surprising as it has not been observed previously on TiO2(110) from simple organic molecules. The coverage dependent yields of ethylene and acetaldehyde correlate well with that of water and hydrogen, respectively. Dehydration dominates at lower EG coverages (< 0.2 ML) and plateaus as the coverage is increased to saturation. Dehydrogenation is observed primarily at higher EG coverages (>0.2 ML). Our results suggest that the observed dehydration and dehydrogenation reactions proceed via different surface intermediates.

  19. Biomass energy analysis for crop dehydration

    SciTech Connect

    Whittier, J.P.; Haase, S.G.; Quinn, M.W. [and others

    1994-12-31

    In 1994, an agricultural processing facility was constructed in southern New Mexico for spice and herb dehydration. Annual operational costs are dominated by energy costs, due primarily to the energy intensity of dehydration. A feasibility study was performed to determine whether the use of biomass resources as a feedstock for a cogeneration system would be an economical option. The project location allowed access to unusual biomass feedstocks including cotton gin trash, pecan shells and in-house residues. A resource assessment of the immediate project area determined that approximately 120,000 bone dry tons of biomass feedstocks are available annually. Technology characterization for the plant energy requirements indicated gasification systems offer fuel flexibility advantages over combustion systems although vendor support and commercial experience are limited. Regulatory siting considerations introduce a level of uncertainty because of a lack of a precedent in New Mexico for gasification technology and because vendors of commercial gasifiers have little experience operating such a facility nor gathering emission data. A public opinion survey indicated considerable support for renewable energy use and biomass energy utilization. However, the public opinion survey also revealed limited knowledge of biomass technologies and concerns regarding siting of a biomass facility within the geographic area. The economic analysis conducted for the study is based on equipment vendor quotations, and indicates there will be difficulty competing with current prices of natural gas.

  20. Dehydration-mediated cluster formation of nanoparticles

    PubMed Central

    Ahn, Sungsook; Joon Lee, Sang

    2015-01-01

    Drying procedure is a powerful method to modulate the bottom-up assembly of basic building component. The initially weak attraction between the components screened in a solution strengthens as the solvent evaporates, organizing the components into structures. Drying is process-dependent, irreversible, and nonequilibrated, thus the mechanism and the dynamics are influenced by many factors. Therefore, the interaction of the solvent and the elements during the drying procedure as well as the resulting pattern formations are strongly related. Nonetheless still many things are open in questions in terms of their dynamics. In this study, nanoscale dehydration procedure is experimentally investigated using a nanoparticle (NP) model system. The role of water is verified in a single NP scale and the patterns of collective NP clusters are determined. Stepwise drying procedures are proposed based on the location from which water is removed. Effective water exodus from a unit NP surface enhances the attractive interaction in nanoscale and induces heterogeneous distribution in microscale. This study provides fundamental proof of systematic relation between the dehydration process and the resultant cluster patterns in hierarchical multiscales. PMID:26077841

  1. Cryoprotective dehydration is widespread in Arctic springtails.

    PubMed

    Sørensen, Jesper Givskov; Holmstrup, Martin

    2011-08-01

    Cryoprotective dehydration (CPD) is a cold tolerance strategy employed by small invertebrates that readily lose water by evaporation when subjected to sub-zero temperatures in the presence of ice. Until now, relatively few species have been investigated using methods by which CPD can be shown. In the present study we investigated the cold tolerance strategy of seven soil arthropod species from the high Arctic Spitzbergen, and compared water content and water loss, body fluid melting points (MP) and survival under cold and desiccating conditions. We tested the hypothesis that CPD is a commonly occurring cold hardiness strategy among soil arthropods. We found that four springtail species (Hypogastrura viatica, Folsomia quadrioculata, Oligaphorura groenlandica and Megaphorura arctica; Collembola) went through severe dehydration and MP equilibration with ambient temperature, and thus overwinter by employing CPD, whereas a beetle (Atheta graminicola) and one of the springtails (Isotoma anglicana) were typical freeze avoiding species over-wintering by supercooling. Desiccation tolerance of the red velvet mite (Neomolgus littoralis) was also investigated; very low water loss rates of this species indicated that it does not survive winter by use of CPD. All in all, the results of the present study confirm the hypothesis that CPD is an effective over-wintering strategy which is widespread within soil arthropods. PMID:21396373

  2. 40 CFR 407.50 - Applicability; description of the dehydrated potato products subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Applicability; description of the dehydrated potato products subcategory. 407.50 Section...PROCESSING POINT SOURCE CATEGORY Dehydrated Potato Products Subcategory § 407.50 Applicability; description of the dehydrated potato products subcategory. The...

  3. 40 CFR 407.50 - Applicability; description of the dehydrated potato products subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Applicability; description of the dehydrated potato products subcategory. 407.50 Section...PROCESSING POINT SOURCE CATEGORY Dehydrated Potato Products Subcategory § 407.50 Applicability; description of the dehydrated potato products subcategory. The...

  4. Geothermal vegetable dehydration at Brady`s Hot Springs, Nevada

    Microsoft Academic Search

    1994-01-01

    This article describes the utilization of the Brady`s Springs geothermal resource for heat generation used in the food dehydration process. This geothermal system is located in the Forty-Mile Desert area of Nevada. Geothermal Food Processors, Inc. of Reno, Nevada started construction of the geothermal vegetable dehydration plant in 1978, and the plant started operations in 1979. The industrial process of

  5. Solids Rheology for Dehydrated Food and Biological Materials

    Microsoft Academic Search

    V. R. N. Telis; J. Telis-Romero; A. L. Gabas

    2005-01-01

    Mechanical properties of food products and biological materials are greatly affected by the drying process and are considered one of the most important quality attributes of dehydrated products. The aim of this work was to review theoretical principles and mathematical modeling, analyzing the measurement techniques and major experimental results that exist in the literature about rheological properties of dehydrated foods

  6. Osmotic dehydration of pineapple: kinetics and product quality

    Microsoft Academic Search

    Expedito T. F. Silveira; M. Shafiur Rahman; Ken A. Buckle

    1996-01-01

    Osmotic dehydration as an intermediate step in air or vacuum drying of pineapple was studied. Osmotic dehydration kinetics indicated that both water loss and solids gain increased with increase of syrup temperature and concentration, the former having much more effect for the range of values tested. Equilibrium kinetics was modelled by defining equilibrium constants and in non-equilibrium period water loss

  7. Retention of nutrients in green leafy vegetables on dehydration.

    PubMed

    Gupta, Sheetal; Gowri, B S; Lakshmi, A Jyothi; Prakash, Jamuna

    2013-10-01

    The objective of the study was to investigate the influence of dehydration on nutrient composition of Amaranthus gangeticus, Chenopodium album, Centella asiatica, Amaranthus tricolor and Trigonella foenum graecum. The green leafy vegetables (GLV) were steam blanched for 5 min after pretreatment and dried in an oven at 60 °C for 10-12 h. The fresh and dehydrated samples were analyzed for selected proximate constituents, vitamins, minerals, antinutrients and dialyzable minerals. Dehydration seems to have little effect on the proximate, mineral and antinutrient content of the GLV. Among the vitamins, retention of ascorbic acid was 1-14%, thiamine 22-71%, total carotene 49-73% and ?-carotene 20-69% respectively, of their initial content. Dialyzable iron and calcium in the fresh vegetables ranged between 0.21-3.5 mg and 15.36-81.33 mg/100 g respectively, which reduced to 0.05-0.53 mg and 6.94-58.15 mg/100 g on dehydration. Dehydration seems to be the simplest convenient technology for preserving these sources of micronutrients, especially when they are abundantly available. Irrespective of the losses of vitamins that take place during dehydration, dehydrated GLV are a concentrated natural source of micronutrients and they can be used in product formulations. Value addition of traditional products with dehydrated GLV can be advocated as a feasible food-based approach to combat micronutrient malnutrition. PMID:24425998

  8. Smackerels of Somethings: Dehydrating Food and How to Use It.

    ERIC Educational Resources Information Center

    Ditzler, Carmen

    1994-01-01

    Provides ideas about how to add variety, flavor, texture, and nutrition to outdoor meals by dehydrating food and using it on camping trips. The goal is to prepare nutritious and appealing meals without spending a lot of money on commercially dehydrated or freeze-dried foods. Includes instructions for rehydrating foods. (LP)

  9. Dehydration accelerates root respiration and impacts sugarbeet raffinose metabolism

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sugarbeet roots lose water during storage and often become severely dehydrated after prolonged storage and at the outer portions of piles which have greater wind and sun exposure. Sucrose loss is known to be elevated in dehydrated roots, although the metabolic processes responsible for this loss ar...

  10. Condensation polyimides

    NASA Technical Reports Server (NTRS)

    Hergenrother, P. M.

    1989-01-01

    Polyimides belong to a class of polymers known as polyheterocyclics. Unlike most other high temperature polymers, polyimides can be prepared from a variety of inexpensive monomers by several synthetic routes. The glass transition and crystalline melt temperature, thermooxidative stability, toughness, dielectric constant, coefficient of thermal expansion, chemical stability, mechanical performance, etc. of polyimides can be controlled within certain boundaries. This versatility has permitted the development of various forms of polyimides. These include adhesives, composite matrices, coatings, films, moldings, fibers, foams and membranes. Polyimides are synthesized through both condensation (step-polymerization) and addition (chain growth polymerization) routes. The precursor materials used in addition polyimides or imide oligomers are prepared by condensation method. High molecular weight polyimide made via polycondensation or step-growth polymerization is studied. The various synthetic routes to condensation polyimides, structure/property relationships of condensation polyimides and composite properties of condensation polyimides are all studied. The focus is on the synthesis and chemical structure/property relationships of polyimides with particular emphasis on materials for composite application.

  11. The evolution of the dehydration in the Antarctic stratospheric vortex

    NASA Astrophysics Data System (ADS)

    VöMel, H.; Oltmans, S. J.; Hofmann, D. J.; Deshler, T.; Rosen, J. M.

    1995-07-01

    In 1994 an intensive program of balloon-borne frost point measurements was performed at McMurdo, Antarctica. During this program a total of 19 frost point soundings was obtained between February 7 and October 5, which cover a wide range of undisturbed through strongly dehydrated situations. Together with several soundings from South Pole station between 1990 and 1994, they give a comprehensive picture of the general development of the dehydration in the Antarctic stratospheric vortex. The period of dehydration typically starts around the middle of June, and a rapid formation of large particles leads to a fast dehydration of the vortex. The evaporation of falling particles leads to rehydration layers, which have significantly higher water vapor concentrations than the undisturbed stratosphere. Through the formation of these rehydration layers in the early stages of the dehydration we can estimate a particle fall speed of ? km/d and thus a mean particle size of 4 ?m. Ice saturation was observed over McMurdo in only two cases and only well after the onset of the dehydration. From the inspection of synoptic maps it then follows that a small cold region inside the vortex seems to be sufficient to dehydrate the entire vortex. Above 20 km the dehydration is completed by the end of July. From the descent of the upper dehydration edge we can estimate a mean descent rate inside the vortex of 1.5 km/month. In McMurdo we observed occasional penetration of the vortex edge in cases where the vortex edge was close to McMurdo, however, these cases seem to have little effect on the bulk of the vortex. A sounding from November 3, 1990, at South Pole shows that the dehydration may persist into November and indicates that there is no significant transport into the vortex throughout winter and early spring.

  12. Pathways for Ethanol Dehydrogenation and Dehydration Catalyzed by Ceria (111) and (100) Surfaces

    SciTech Connect

    Beste, Ariana [ORNL; Overbury, Steven {Steve} H [ORNL

    2015-01-01

    We have performed computations to better understand how surface structure affects selectivity in dehydrogenation and dehydration reactions of alcohols. Ethanol reactions on the (111) and (100) ceria surfaces were studied starting from the dominant surface species, ethoxy. We used DFT (PBE+U) to explore reaction pathways leading to ethylene and acetaldehyde and calculated estimates of rate constants employing transition state theory. To assess pathway contributions, we carried out kinetic analysis. Our results show that intermediate and transition state structures are stabilized on the (100) surface compared to the (111) surface. Formation of acetaldehyde over ethylene is kinetically and thermodynamically preferred on both surfaces. Our results are consistent with temperature programmed surface reaction and steady-state experiments, where acetaldehyde was found as the main product and evidence was presented that ethylene formation at higher temperature originates from changes in adsorbate and surface structure.

  13. Two-stage dehydration of sugars

    DOEpatents

    Holladay, Johnathan E. (Kennewick, WA); Hu, Jianli (Kennewick, WA); Wang, Yong (Richland, WA); Werpy, Todd A. (West Richland, WA)

    2009-11-10

    The invention includes methods for producing dianhydrosugar alcohol by providing an acid catalyst within a reactor and passing a starting material through the reactor at a first temperature. At least a portion of the staring material is converted to a monoanhydrosugar isomer during the passing through the column. The monoanhydrosugar is subjected to a second temperature which is greater than the first to produce a dianhydrosugar. The invention includes a method of producing isosorbide. An initial feed stream containing sorbitol is fed into a continuous reactor containing an acid catalyst at a temperature of less than 120.degree. C. The residence time for the reactor is less than or equal to about 30 minutes. Sorbitol converted to 1,4-sorbitan in the continuous reactor is subsequently provided to a second reactor and is dehydrated at a temperature of at least 120.degree. C. to produce isosorbide.

  14. Dropwise condensation

    PubMed Central

    Leach, R. N.; Stevens, F.; Langford, S. C.; Dickinson, J. T.

    2008-01-01

    Dropwise condensation of water vapor from a naturally cooling, hot water reservoir onto a hydrophobic polymer film and a silanized glass slide was studied by direct observation and simulations. The observed drop growth kinetics suggest that smallest drops grow principally by the diffusion of water adsorbed on the substrate to the drop perimeter, while drops larger than 50 ?m in diameter grow principally by direct deposition from the vapor onto the drop surface. Drop coalescence plays a critical role in determining the drop size distribution, and stimulates the nucleation of new, small drops on the substrates. Simulations of drop growth incorporating these growth mechanisms provide a good description of the observed drop size distribution. Because of the large role played by coalescence, details of individual drop growth make little difference to the final drop size distribution. The rate of condensation per unit substrate area is especially high for the smallest drops, and may help account for the high heat transfer rates associated with dropwise condensation relative to filmwise condensation in heat exchange applications. PMID:17014129

  15. Hydrothermal Synthesis and Dehydration of CaTeO3(H2O): An Original Route to Generate New CaTeO3 Polymorphs.

    PubMed

    Poupon, Morgane; Barrier, Nicolas; Petit, Sebastien; Clevers, Simon; Dupray, Valerie

    2015-06-15

    CaTeO3(H2O) was obtained from microwave-assisted hydrothermal synthesis as a polycrystalline sample material. The dehydration reaction was followed by thermal analysis (thermogravimetric/differential scanning calorimetry) and temperature-dependent powder X-ray diffraction and leads to a new ?-CaTeO3 polymorph. The crystal structures of CaTeO3(H2O) and ?-CaTeO3 were solved ab initio from PXRD data. CaTeO3(H2O) is non-centrosymmetric: P21cn; Z = 8; a = 14.785?49(4) Å; b = 6.791?94(3) Å; c = 8.062?62(3) Å. This layered structure is related to the ones of MTeO3(H2O) (M = Sr, Ba) with layers built of edge-sharing [CaO6(H2O)] polyhedra and are capped of each side by [Te(IV)O3E] units. Adjacent layers are stacked along the a-axis and are held together by H-bonds via the water molecules. The dehydration reaction starts above 120 °C. The transformation of CaTeO3(H2O) into ?-CaTeO3 (P21ca; Z = 8; a = 13.3647(6) Å; b = 6.5330(3) Å; c = 8.1896(3) Å) results from topotactic process with layer condensation along the a-axis and the 1/2b? translation of intermediate layers. Thus, ?-CaTeO3 stays non-centrosymmetric. The characteristic layers of CaTeO3(H2O) are also maintained in ?-CaTeO3 but held together via van der Waals bonds instead of H-bonds through water molecules. Electron localization function and dipole moment calculations were also performed. For both structures and over each unit cell, the dipole moments are aligned antiparallel with net dipole moments of 3.94 and 0.47 D for CaTeO3(H2O) and ?-CaTeO3, respectively. The temperature-resolved second harmonic generation (TR-SHG) measurements, between 30 and 400 °C, show the decreasing of the SHG intensity response from 0.39 to 0.06 × quartz for CaTeO3(H2O) and ?-CaTeO3, respectively. PMID:26035739

  16. Proposal for New Experimental Tests of the Bose-Einstein Condensation Mechanism for Low-Energy Nuclear Reaction and Transmutation Processes in Deuterium Loaded - and Nano-Scale Cavities

    NASA Astrophysics Data System (ADS)

    Kim, Yeong E.; Koltick, David S.; Reifenberger, Ronald G.; Zubarev, Alexander L.

    2006-02-01

    Most of experimental results of low-energy nuclear reaction (LENR) reported so far cannot be reproduced on demand. There have been persistent experimental results indicating that the LENR and transmutation processes in condensed matters (LENRTPCM) are surface phenomena rather than bulk phenomena. Recently proposed Bose-Einstein condensation (BEC) mechanism may provide a suitable theoretical description of the surface phenomena. New experiments are proposed and described for testing the BEC mechanism for LENR and transmutation processes in micro- and nano-scale traps. (1) We propose the use of micro- or nano-porous conducting materials as a cathode in electrolysis experiments with heavy water with or without Li in order to stabilize the active surface spots and to enhance the effect for the purpose of improving the reproducibility of excess heat generation and nuclear emission. (2) We propose new experimental tests of the BEC mechanism by measuring the pressure and temperature dependence of LENR events using deuterium gas and these deuterated metals with or without Li. If the LENRTPCM are surface phenomena, the proposed use of micro-/nano-scale porous materials is expected to enhance and scale up the LENRTPCM effects by many order of magnitude, and thus may lead to better reproductivity and theoretical understanding of the phenomena.

  17. Immobilisation increases yeast cells' resistance to dehydration-rehydration treatment.

    PubMed

    Borovikova, Diana; Rozenfelde, Linda; Pavlovska, Ilona; Rapoport, Alexander

    2014-08-20

    This study was performed with the goal of revealing if the dehydration procedure used in our new immobilisation method noticeably decreases the viability of yeast cells in immobilised preparations. Various yeasts were used in this research: Saccharomyces cerevisiae cells that were rather sensitive to dehydration and had been aerobically grown in an ethanol-containing medium, a recombinant strain of S. cerevisiae grown in aerobic conditions which were completely non-resistant to dehydration and an anaerobically grown bakers' yeast strain S. cerevisiae, as well as a fairly resistant Pichia pastoris strain. Experiments performed showed that immobilisation of all these strains essentially increased their resistance to a dehydration-rehydration treatment. The increase of cells' viability (compared with control cells dehydrated in similar conditions) was from 30 to 60%. It is concluded that a new immobilisation method, which includes a dehydration stage, does not lead to an essential loss of yeast cell viability. Correspondingly, there is no risk of losing the biotechnological activities of immobilised preparations. The possibility of producing dry, active yeast preparations is shown, for those strains that are very sensitive to dehydration and which can be used in biotechnology in an immobilised form. Finally, the immobilisation approach can be used for the development of efficient methods for the storage of recombinant yeast strains. PMID:24886905

  18. Low-temperature synthesis of boron carbide powder from condensed boric acid–glycerin product

    Microsoft Academic Search

    Masaki Kakiage; Naoki Tahara; Ikuo Yanase; Hidehiko Kobayashi

    2011-01-01

    Crystalline boron carbide (B4C) powder was synthesized by the carbothermal reduction of a condensed product formed from boric acid (H3BO3) and glycerin (C3H8O3). The condensed product was prepared by dehydration after directly mixing equimolar amounts of H3BO3 and glycerin, which was followed by pyrolysis in air to obtain a precursor powder from which the excess carbon had been eliminated. The

  19. Transient dehydration of lungs in tail-suspended rats

    NASA Technical Reports Server (NTRS)

    Hargens, A. R.; Steskal, J.; Morey-Holton, E. R.

    1985-01-01

    The fluid balance in the lungs of rats exposed to head-down tilt is examined. Six Munich-Wister rats were suspended for 7 days and 10 Sprague-Dawley rats for 14 days using the technique of Morey (1979). The water contents of the lungs of the suspended and a control group are calculated and compared. The data reveal that the two-days suspended rats had dehydrated lungs; however, the lungs of the 14-day suspended and control group rats were similar. It is noted that the dehydration in the 2-day suspended rats is caused by general dehydration not the head-tilt position.

  20. Low Energy Nuclear Reactions: 2007 Update

    Microsoft Academic Search

    Steven B. Krivit

    2007-01-01

    This paper presents an overview of low energy nuclear reactions, a subset of the field of condensed matter nuclear science. Condensed matter nuclear science studies nuclear effects in and\\/or on condensed matter, including low energy nuclear reactions, an entirely new branch of science that gained widespread attention and notoriety beginning in 1989 with the announcement of a previously unrecognized source

  1. Comparison of clinical and biochemical markers of dehydration with the clinical dehydration scale in children: a case comparison trial

    PubMed Central

    2014-01-01

    Background The clinical dehydration scale (CDS) is a quick, easy-to-use tool with 4 clinical items and a score of 1–8 that serves to classify dehydration in children with gastroenteritis as no, some or moderate/severe dehydration. Studies validating the CDS (Friedman JN) with a comparison group remain elusive. We hypothesized that the CDS correlates with a wide spectrum of established markers of dehydration, making it an appropriate and easy-to-use clinical tool. Methods This study was designed as a prospective double-cohort trial in a single tertiary care center. Children with diarrhea and vomiting, who clinically required intravenous fluids for rehydration, were compared with minor trauma patients who required intravenous needling for conscious sedation. We compared the CDS with clinical and urinary markers (urinary electrolytes, proteins, ratios and fractional excretions) for dehydration in both groups using receiver operating characteristic (ROC) curves to determine the area under the curve (AUC). Results We enrolled 73 children (male?=?36) in the dehydration group and 143 (male?=?105) in the comparison group. Median age was 32 months (range 3–214) in the dehydration and 96 months (range 2.6-214 months, p?dehydration group and 0 in the comparison group (p?dehydrated group: difference in heart rate, diastolic blood pressure, urine sodium/potassium ratio, urine sodium, fractional sodium excretion, serum bicarbonate, and creatinine measurements. The best markers for dehydration were urine Na and serum bicarbonate (ROC AUC?=?0.798 and 0.821, respectively). CDS was most closely correlated with serum bicarbonate (Pearson r?=?-0.3696, p?=?0.002). Conclusion Although serum bicarbonate is not the gold standard for dehydration, this study provides further evidence for the usefulness of the CDS as a dehydration marker in children. Trial registration Registered at ClinicalTrials.gov (NCT00462527) on April 18, 2007. PMID:24935348

  2. Newly developed encapsulation-dehydration protocol for plantcryopreservation.

    PubMed

    Sakai, A; Matsumoto, T; Hirai, D; Niino, T

    2000-01-01

    A simplified and efficient encapsulation-dehydration protocol, which is a compromise between vitrification and encapsulation-dehydration, was presented for plant cryopreservation. In this protocol, during the encapsulation process, the apices precultured with 0.3 M sucrose for 16 h were simultaneously osmoprotected with a mixture of 02 M glycerol plus 0.4 M sucrose for 1 h. These encapsulated apices were directly dehydrated with dry silica gel prior to a plunge into LN without the pretreatment of 0.8M sucrose for 16 h. This protocol produced much higher rates of recovery growth in the three plant species tested (wasabi, chrysanthemum, and mint) than those cryopreserved by the conventional encapsulation-dehydration. This protocol also considerably reduced the time needed for the cryogenic procedure. Thus, this new protocol appears promising for cryopreservation of shoot apices and other explants. PMID:12148065

  3. Proper Design Saves Energy for Molecular Sieve Dehydration Systems

    E-print Network

    Barrow, J. A.; Veldman, R.

    1984-01-01

    operation, freezeups, and lost plant production. The molecular sieve system is a batch process. One tower dehydrates while the other tower is being regenerated by heating. Energy can be conserved in several ways....

  4. Experimental apparatus for simultaneous dehydration and sweetening of natural gas 

    E-print Network

    Pace, Christopher Lee

    1997-01-01

    An experimental apparatus was designed and built for the purpose of studying the feasibility of solvent mixtures for the simultaneous dehydration and sweetening of natural gas. The apparatus is versatile and can be used to study gas-solvent systems...

  5. In situ X-ray observation of dehydration and EoS of chlorite under high pressure and temperature

    NASA Astrophysics Data System (ADS)

    Inoue, T.; Suenami, H.; Kikegawa, T.

    2014-12-01

    Water in hydrous minerals has been transported to deep Earth's interior by subducting slab, which dehydrate at certain pressure and temperature. The existence of deep Earth's water affects the physical properties of Earth's mantle minerals. Therefore it is important to study the effect of water for the subducting slab materials. Serpentine ((Mg,Fe)6Si4O10(OH)8) is major hydrous mineral in subducting slab, and chlorite ((Mg,Fe,Al)6(Si,Al)4O10(OH)8) should be also important hydrous mineral in the subducting slab because Al is included in slab materials. In this study, the dehydration reactions and P-V-T EoS of chlorite were determined by time-resolved X-ray diffraction analysis under high pressure and temperature using MAX80, PF-AR, KEK. We found that chlorite was quickly dehydrated to forsterite + pyrope + fluid within 1 hour at 3 - 7 GPa when across the phase equilibrium boundary. On the other hand, the kinetic boundary was observed above 7 GPa because of low temperature phase equilibrium boundary, and the dehydration product was Mg-sursassite + unknown + fluid. In the EoS study, we observed compressibility change, i.e. elastic softening behavior in chlorite at around 4 GPa. This behavior is consistent with the case of antigorite (serpentine) (e.g. Yang et al., 2014). The details of P-V-T results will be presented.

  6. Scrutinizing Gypsum Board Thermal Performance at Dehydration Temperatures

    Microsoft Academic Search

    D. Kontogeorgos; I. Mandilaras; M. Founti

    2011-01-01

    This article investigates the thermal performance of gypsum boards in the dehydration temperature region, where pronounced chemical reactivity is anticipated. Gypsum board samples were gradually heated up to 300°C, using a low heating rate. Temperature measurements at pre-selected board locations indicated three distinct stages of gypsum dehydration; free moisture evaporation, transformation of calcium sulfate dihydrate to calcium sulfate hemi-hydrate and

  7. A model for the dehydration of waterborne basecoat

    Microsoft Academic Search

    Paul Henshaw; Lindita Prendi; Tony Mancina

    2006-01-01

    In vehicle manufacturing, a common topcoat process sequence is the application of a waterborne basecoat, partial dehydration,\\u000a application of a solventborne clearcoat, then curing at approximately 150?C. Anecdotal evidence suggests that under “harsh”\\u000a (high temperature and velocity) dehydration conditions, a skin can be formed, which can trap excess water in the basecoat.\\u000a Upon curing, the excess water forms vapor that

  8. Seawater drinking restores water balance in dehydrated harp seals

    Microsoft Academic Search

    Ole-Jakob How; Erling S. Nordøy

    2007-01-01

    The purpose of this study was to answer the question of whether dehydrated harp seals (Phoca groenlandica) are able to obtain a net gain of water from the intake of seawater. Following 24 h of fasting, three subadult female harp\\u000a seals were dehydrated by intravenous administration of the osmotic diuretic, mannitol. After another 24 h of fasting, the\\u000a seals were given 1,000 ml

  9. Quality evaluation of onion (Allium cepa) cultivars for dehydration

    E-print Network

    Talley, Linda Jean

    1979-01-01

    QUALITY EVALUATION OF ONION (Allium ~ce a) CULTIVARS FOR DEHYDRATION A Thesis by LINDA JEAN TALLEY Submitted to the Graduate College of Texas A8M Uni vers i ty in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE... December 1979 Major Subject: Food Science and Technology EQUALITY EVALUATION OF ONION (Allium ~ce a) CULTIVARS FOR DEHYDRATION A Thesis by LINDA JEAN TALLEY Approved as to style and content by: (Chairman of Committee) (Head of Department) ~4'EZ...

  10. Renal tubular vasopressin receptors downregulated by dehydration

    SciTech Connect

    Steiner, M.; Phillips, M.I. (Univ. of Florida, Gainesville (USA))

    1988-03-01

    Receptors for arginine vasopressin (AVP) were characterized in tubular epithelial basolateral membranes (BL membranes) prepared from the kidneys of male Spraque-Dawley rats. Association of ({sup 3}H)AVP was rapid, reversible, and specific. Saturation studies revealed a single class of saturable binding sites with a maximal binding (B{sub max}) of 184 {plus minus} 15 fmol/mg protein. The V{sub 2} receptor antagonist was more than 3,700 times as effective in displacing ({sup 3}H)AVP than was the V{sub 1} antagonist. To investigate the physiological regulation of vasopressin receptors, the effects of elevated levels of circulating AVP on receptor characteristics were studied. Seventy-two-hour water deprivation significantly elevated plasma osmolality and caused an 11.5-fold increase in plasma (AVP). Scatchard analysis revealed a 38% decreased in the number of AVP receptors on the BL membranes from dehydrated animals. The high-affinity binding sites on the BL membranes fit the pharmacological profile for adenylate cyclase-linked vasopressin receptors (V{sub 2}), which mediate the antidiuretic action of the hormone. The authors conclude that physiologically elevated levels of AVP can downregulate vasopressin receptors in the kidney.

  11. When to treat dehydration in a terminally ill patient?

    PubMed

    Fainsinger, R L; Bruera, E

    1997-05-01

    The need to treat dehydration in terminally ill patients has become a very controversial topic. Numerous reports in the literature illustrate opposing view-points from both clinical and ethical perspectives. Arguments for the maintenance of hydration in terminally ill patients have tended to come from "the traditional medical model". Many health care professionals looking after terminally ill patients have reacted to the generalized use of intravenous fluids in dying patients and the perceived negative effects of this management. Our palliative care group has argued that the viewpoint that dehydration in dying patients is not a cause of symptom distress overlooks commonly reported problems, such as agitated delirium, that can be prevented or reversed by the management of dehydration. This review presents a summary of the traditional arguments, a different perspective on the controversy, biochemical parameters reported in terminally ill cancer patients, recent dehydration research, and the use of hypodermoclysis and rectal hydration. We conclude that the data reported to date are insufficient to allow a final conclusion on the benefit or harm of dehydration in terminally ill patients. Nevertheless, it is worth considering that while some dying patients may not suffer any ill effects from dehydration, there may be others who do manifest symptoms, such as confusion or opioid toxicity, that might be alleviated or prevented by parenteral hydration. PMID:9176966

  12. Whole transcriptome organisation in the dehydrated supraoptic nucleus.

    PubMed

    Hindmarch, C C T; Franses, P; Goodwin, B; Murphy, D

    2013-12-01

    The supraoptic nucleus (SON) is part of the central osmotic circuitry that synthesises the hormone vasopressin (Avp) and transports it to terminals in the posterior lobe of the pituitary. Following osmotic stress such as dehydration, this tissue undergoes morphological, electrical and transcriptional changes to facilitate the appropriate regulation and release of Avp into the circulation where it conserves water at the level of the kidney. Here, the organisation of the whole transcriptome following dehydration is modelled to fit Zipf's law, a natural power law that holds true for all natural languages, that states if the frequency of word usage is plotted against its rank, then the log linear regression of this is -1. We have applied this model to our previously published euhydrated and dehydrated SON data to observe this trend and how it changes following dehydration. In accordance with other studies, our whole transcriptome data fit well with this model in the euhydrated SON microarrays, but interestingly, fit better in the dehydrated arrays. This trend was observed in a subset of differentially regulated genes and also following network reconstruction using a third-party database that mines public data. We make use of language as a metaphor that helps us philosophise about the role of the whole transcriptome in providing a suitable environment for the delivery of Avp following a survival threat like dehydration. PMID:24345907

  13. Psychomotor and physiological responses to prolong walking in the heat in hydrated and dehydrated conditions among relaxation-trained army reserved personnel

    Microsoft Academic Search

    Hairul Anuar Hashim; Zabidi Azhar Hussin; Chen Chee Keong; Asok Kumar Ghosh

    2010-01-01

    The present study examined the effects of prolonged walking in the heat on choice reaction time, heart rate and rectal temperature among army reserved personnel. Using purposive sampling, 23 male reserved army personnel were recruited for this study and they were randomly assigned into hydrated and dehydrated groups. The experimental protocols consist of two experimental sessions (pre- and post-relaxation training).

  14. Ni(ii)-catalyzed dehydrative alkynylation of unactivated (hetero)aryl C-H bonds using oxygen: a user-friendly approach.

    PubMed

    Liu, Yan-Hua; Liu, Yue-Jin; Yan, Sheng-Yi; Shi, Bing-Feng

    2015-07-25

    Ni(ii)-catalyzed dehydrative alkynylation of unactivated C(sp(2))-H bonds with terminal alkynes under atmospheric pressure of oxygen was developped. This reaction features the use of catalytic amounts of nickel as the catalyst and O2 as the sole oxidant, providing a user-friendly approach to the synthesis of aryl alkynes. PMID:26099578

  15. Muscovite dehydration melting in Si-rich metapelites: microstructural evidence from trondhjemitic migmatites, Roded, Southern Israel

    NASA Astrophysics Data System (ADS)

    Anenburg, Michael; Katzir, Yaron

    2014-02-01

    Making a distinction between partial melting and subsolidus segregation in amphibolite facies migmatites is difficult. The only significant melting reactions at lowpressures, either vapour saturated or muscovite dehydration melting, do not produce melanocratic peritectic phases. If protoliths are Si-rich and K-poor, then peritectic sillimanite and K-feldspar will form in scarce amounts, and may be lost by retrograde rehydration. The Roded migmatites of southern Israel (northernmost Arabian Nubian Shield) formed at P = 4.5 ± 1 kbar and T ? 700 °C and include Si-rich, K-poor paragneissic paleosome and trondhjemitic leucosomes. The lack of K-feldspar in leucosomes was taken as evidence for the non-anatectic origin of the Roded migmatites (Gutkin and Eyal, Isr J Earth Sci 47:117, 1998). It is shown here that although the Roded migmatites experienced significant post-peak deformation and recrystallization, microstructural evidence for partial melting is retained. Based on these microstructures, coupled with pseudosection modelling, indicators of anatexis in retrograded migmatites are established. Phase diagram modelling of neosomes shows the onset of muscovite dehydration melting at 4.5 kbar and 660 °C, forming peritectic sillimanite and K-feldspar. Adjacent non-melted paleosomes lack muscovite and would thus not melt by this reaction. Vapour saturation was not attained, as it would have formed cordierite that does not exist. Furthermore, vapour saturation would not allow peritectic K-feldspar to form, however K-feldspar is ubiquitous in melanosomes. Direct petrographic evidence for anatexis is rare and includes euhedral plagioclase phenocrysts in leucosomes and quartz-filled embayments in corroded plagioclase at leucosome-melanosome interfaces. In deformed and recrystallized rocks muscovite dehydration melting is inferred by: (1) lenticular K-feldspar enclosed by biotite in melanosomes, (2) abundant myrmekite in leucosomes, (3) muscovite-quartz symplectites after sillimanite in melanosomes and associated with myrmekite in leucosomes. While peritectic K-feldspar formed in melanosomes by muscovite dehydration melting reaction, K-feldspar crystallizing from granitic melt in adjacent leucosome was myrmekitized. Excess potassium was used in rehydration of sillimanite to muscovite.

  16. Thermogravimetric study of the dehydration and reduction of red mud

    NASA Astrophysics Data System (ADS)

    Teplov, O. A.; Korenovskii, N. L.; Lainer, Yu. A.

    2015-01-01

    The processes of drying and reduction of red mud in the pure state and with coal additions in vacuum or in gaseous media (helium, hydrogen) have been experimentally studied by thermogravimetry using a Setaram TAG24 thermogravimetric analyzer. The minimum total weight loss (˜20%) is observed for red mud samples without additives in forevacuum, and the maximum loss (˜38%) is detected in samples with coal. It is demonstrated that, for this type of red mud with iron oxide Fe2O3, water molecules are bonded in the form of iron hydroxide Fe2O3 · 3H2O rather than goethite FeOOH. The peak of magnetite formation is observed in differential thermogravimetry (DTG) curve in the range 270-400°C. The simulation of the magnetite dehydration and formation rates under experimental conditions in the relevant temperature ranges agrees with the experimental data. A peak of wustite formation in hydrogen above ˜600°C is recorded in a DTG curve, and the removal of one-third of sodium oxide, which is likely not to be fixed into strong sodium alumosilicate, is observed in the range 800-1000°C. The peak detected in the DTG curve of the mud with charcoal in helium in the range 350-450°C is similar to the peak of hematite reduction in magnetite in a hydrogen atmosphere. The most probable source of hydrogen-containing gases in this temperature range consists of the residual hydrocarbons of charcoal. The reduction reactions of disperse iron oxides with coal proceed only at temperatures above 600°C. These processes occur in the same temperature range (600-900°C) both in forevacuum and in a helium atmosphere. It is experimentally demonstrated that sintering process occurs in the mud in the temperature range 450-850°C.

  17. A model of teneral dehydration in Glossina.

    PubMed

    Childs, S J

    2014-03-01

    The results of a long-established investigation into teneral transpiration are used as a rudimentary data set. These data are not complete in that all are at 25°C and the temperature-dependence cannot, therefore, be resolved. An allowance is, nonetheless, made for the outstanding temperature-dependent data. The data are generalised to all humidities, levels of activity and, in theory, temperatures, by invoking the property of multiplicative separability. In this way a formulation, which is a very simple, first order, ordinary differential equation, is devised. The model is extended to include a variety of Glossina species by resorting to their relative, resting water loss rates in dry air. The calculated, total water loss is converted to the relevant humidity, at 24°C, that which produced an equivalent water loss in the pupa, in order to exploit an adaption of an established survival relationship. The resulting computational model calculates total, teneral water loss, consequent mortality and adult recruitment. Surprisingly, the postulated race against time, to feed, applies more to the mesophilic and xerophilic species, in that increasing order. So much so that it is reasonable to conclude that, should Glossina brevipalpis survive the pupal phase, it will almost certainly survive to locate a host, without there being any significant prospect of death from dehydration. With the conclusion of this work comes the revelation that the classification of species as hygrophilic, mesophilic and xerophilic is largely true only in so much as their third and fourth instars are and, possibly, the hours shortly before eclosion. PMID:24333159

  18. Towards high water permeability in triazine-framework-based microporous membranes for dehydration of ethanol.

    PubMed

    Tang, Yu Pan; Wang, Huan; Chung, Tai Shung

    2015-01-01

    The microstructural evolution of a series of triazine framework-based microporous (TFM) membranes under different conditions has been explored in this work. The pristine TFM membrane is in?situ fabricated in the course of polymer synthesis via a facile Brønsted-acid-catalyzed cyclotrimerizaiton reaction. The as-synthesized polymer exhibits a microporous network with high thermal stability. The free volume size of the TFM membranes gradually evolved from a unimodal distribution to a bimodal distribution under annealing, as analyzed by positron annihilation lifetime spectroscopy (PALS). The emergence of the bimodal distribution is probably ascribed to the synergetic effect of quenching and thermal cyclization reaction. In addition, the fractional free volume (FFV) of the membranes presents a concave trend with increasing annealing temperature. Vapor sorption tests reveal that the mass transport properties are closely associated with the free volume evolution, which provides an optimal condition for dehydration of biofuels. A promising separation performance with extremely high water permeability has been attained for dehydration of an 85?wt?% ethanol aqueous solution at 45?°C. The study on the free volume evolution of the TFM membranes may provide useful insights about the microstructure and mass transport behavior of the microporous polymeric materials. PMID:25394279

  19. Dehydration in the tropical tropopause layer: A possible sink of inorganic bromine?

    NASA Astrophysics Data System (ADS)

    Aschmann, J.; Sinnhuber, B.-M.

    2012-04-01

    Recent studies have shown the importance of bromine very short-lived substances (VSLS) for the stratospheric bromine budget and their potential impact on ozone depletion. In this study, bromine loading in the tropical upper troposphere/lower stratosphere (UTLS) due to VSLS is investigated with a 3D chemical transport model with a detailed chemistry scheme, including parametrizations of particle adsorption and scavenging as well as heterogeneous reactions on corresponding surfaces. On the source gas side, the long-lived halons and methyl bromide and the two most important bromine short-lived substances, bromoform and dibromomethane, are included. On the other hand, the partitioning of inorganic bromine product gases (Bry) is also explicitly calculated. Our results suggest that loss of soluble inorganic bromine in the tropical UTLS due to dehydration is negligible, in contrast to most earlier studies. The main reasons can be summarized as follows: The majority of bromine short-lived source gases is still intact at the UTLS and is therefore not susceptible to dehydration. Furthermore, the fraction of inorganic bromine which is actually adsorbed on ice particles is generally lower than 25%. Finally, the model shows that the small amount of adsorbed bromine that could be scavenged is released efficiently into gas phase by heterogeneous reactions.

  20. Characterization and Thermal Dehydration Kinetics of Highly Crystalline Mcallisterite, Synthesized at Low Temperatures

    PubMed Central

    Senberber, Fatma Tugce

    2014-01-01

    The hydrothermal synthesis of a mcallisterite (Mg2(B6O7(OH)6)2·9(H2O)) mineral at low temperatures was characterized. For this purpose, several reaction temperatures (0–70°C) and reaction times (30–240?min) were studied. Synthesized minerals were subjected to X-ray diffraction (XRD), fourier transform infrared (FT-IR), and Raman spectroscopies and scanning electron microscopy (SEM). Additionally, experimental analyses of boron trioxide (B2O3) content and reaction yields were performed. Furthermore, thermal gravimetry and differential thermal analysis (TG/DTA) were used for the determination of thermal dehydration kinetics. According to the XRD results, mcallisterite, which has a powder diffraction file (pdf) number of “01-070-1902,” was formed under certain reaction parameters. Pure crystalline mcallisterite had diagnostic FT-IR and Raman vibration peaks and according to the SEM analysis, for the minerals which were synthesized at 60°C and 30?min of reaction time, particle size was between 398.30 and 700.06?nm. Its B2O3 content and reaction yield were 50.80 ± 1.12% and 85.80 ± 0.61%, respectively. Finally, average activation energies (conversion values (?) that were selected between 0.1 and 0.6) were calculated as 100.40?kJ/mol and 98.31?kJ/mol according to Ozawa and Kissinger-Akahira-Sunose (KAS) methods, respectively. PMID:24719585

  1. Characterization of NOx Species in Dehydrated and Hydrated Na- and Ba-Y, FAU Zeolites Formed in NO? Adsorption

    SciTech Connect

    Szanyi, Janos; Kwak, Ja Hun; Burton, Sarah D.; Rodriguez, J. A.; Peden, Charles HF

    2006-02-01

    Adsorbed ionic NOx species formed upon the interaction of NO? with dehydrated or hydrated Na-, and Ba-Y, FAU zeolites were characterized using FTIR/TPD, solid state NMR, and XANES techniques. NO? disproportionates on both dehydrated catalyst materials forming NO? and NO?? species. These ionic species are stabilized by their interactions with the negatively charged zeolite framework and the charge compensating cations (Na? and Ba²?), respectively. Although the nature of the adsorbed NOx species formed on the two catalysts is similar, their thermal stabilities are strongly dependent on the charge compensating cations. In the presence of water in the channels of these zeolite materials new paths open for reactions between NO? and H?O, and NO? and H?O, resulting in significant changes in the adsorbed ionic species observed. These combined spectroscopic investigations afforded the understanding of the interactions between water and the NO? on these zeolite catalysts.

  2. Functional and technological potential of dehydrated Phaseolus vulgaris L. flours.

    PubMed

    Ramírez-Jiménez, A K; Reynoso-Camacho, R; Mendoza-Díaz, S; Loarca-Piña, G

    2014-10-15

    The effect of cooking followed by dehydration was evaluated on the bioactive composition, antioxidant activity and technological properties of two varieties (Negro 8025 and Bayo Madero) of common beans. Quercetin, rutin, and phenolic acids were the most abundant phenolics found. Cooking processes resulted in decreased values of some phenolic compounds and antioxidant capacity. A subsequent dehydration increased TEAC values, resistant starch content and decreased starch digestibility. Oligosaccharides and dietary fibre were preserved in both treatments. Variety had a strong impact on phytochemical profile, being Negro 8025 that exhibited the highest content of most of the compounds assessed. Water absorption index (WAI) and oil absorption capacity (OAC) were determined in order to measure technological suitability. Dehydration produced flours with stable WAI and low oil pick up. The results suggest that the flours of Negro 8025 beans have a good potential to be considered as functional ingredient for healthy food products. PMID:24837948

  3. Dehydration of erythromycin dihydrate: a microscopy-FTIR application

    NASA Astrophysics Data System (ADS)

    Smith, M. A.; Chao, Robert S.; Bergren, M. S.; Clark, D. A.

    1989-12-01

    A novel application of microscopy-FTIR to monitor the dehydration of some hydrate compounds has been established, and some major instrumental parameters are identified. An application to erythromycin dihydrate indicated that the most notable spectral changes before and after dehydration are observed in the carbonyl region, particularly the lactone carbonyl band. Spectral comparison with conventional FTIR preparations, such as Nujol and KBR methods, are pre-sented to demonstrate the dehydration mechanism of erythromycin dihydrate. Also presented are the differential scanning calorimetry (DSC) and hot stage microscope (HSM) data to support the hypothesis that the FTIR-microscope accessory induces a transformation of erythromycin dihydrate into a metastable anhydrate form which will rehydrate rapidly when water vapor is present. With further thermal treatment the metastable form would convert to a stable anhydrate form via an amorphous form.

  4. The dehydration of potassium alum induced by shock loading

    NASA Astrophysics Data System (ADS)

    Kishimura, Hiroaki; Imasu, Yuhta; Matsumoto, Hitoshi

    2013-06-01

    Shock-induced dehydration and structural change on potassium alum, KAl(SO4)2 .12H2O, has been studied up to a peak pressure of 8 GPa. The shock-recovered samples have been characterized using Raman spectroscopy, x-ray diffraction (XRD), and a scanning electron microscopy (SEM). Although the sample shocked at 5 GPa are consolidated and recovered, no evidence for structural change or dehydration is obtained. However, prominent change of texture and color of the recovered sample shocked at 8 GPa is observed. The XRD results reveal that the recovered sample shocked at 8 GPa consists of anhydrous potassium alum crystals with amorphous. This structure differs from that of dehydrated alum caused by heat. The critical pressure for the shock-induced phase transition is close to the transition pressure from alum crystal to amorphous phase, which is obtained by static pressure loading.

  5. Heat shock proteins contribute to mosquito dehydration tolerance

    PubMed Central

    Benoit, Joshua B.; Lopez-Martinez, Giancarlo; Phillips, Zachary P.; Patrick, Kevin R.; Denlinger, David L.

    2009-01-01

    This study examines the responses of heat shock protein transcripts, Hsp70 and Hsp90, to dehydration stress in three mosquito species, Aedes aegypti, Anopheles gambiae and Culex pipiens. We first defined the water balance attributes of adult females of each species, monitored expression of the hsp transcripts in response to dehydration, and then knocked down expression of the transcripts using RNA interference (RNAi) to evaluate potential functions of the Hsps in maintenance of water balance. Fully hydrated females of all three species contained nearly the same amount of water (66–68%), but water loss rates differed among the species, with A. aegypti having the lowest water loss rate (2.6%/h), followed by C.pipiens (3.3%/h), and A. gambiae (5.1%/h). In all three species water could be replaced only by drinking water (or blood). Both A. aegypti and C. pipiens tolerated a loss of 36% of their body water, but A. gambiae was more vulnerable to water loss, tolerating a loss of only 29% of its body water. Dehydration elicited expression of hsp70 in all three species, but only C. pipiens continued to express this transcript during rehydration. Hsp90 was constitutively expressed and expression levels remained fairly constant during dehydration and rehydration, except expression was not noted during rehydration of C. pipiens. Injection of dsRNA to knock down expression of hsp70 (83% reduction) and hsp90 (46% reduction) in A. aegypti did not alter water content or water loss rates, but the dehydration tolerance was lower. Instead of surviving a 36% water loss, females were able to survive only a 28% water loss in response to RNAi directed against hsp70 and a 26% water loss when RNAi was directed against hsp90. These results indicate a critical function for these Hsps in mosquito dehydration tolerance PMID:19782687

  6. Heat shock proteins contribute to mosquito dehydration tolerance.

    PubMed

    Benoit, Joshua B; Lopez-Martinez, Giancarlo; Phillips, Zachary P; Patrick, Kevin R; Denlinger, David L

    2010-02-01

    This study examines the responses of heat shock protein transcripts, Hsp70 and Hsp90, to dehydration stress in three mosquito species, Aedes aegypti, Anopheles gambiae and Culex pipiens. We first defined the water balance attributes of adult females of each species, monitored expression of the hsp transcripts in response to dehydration, and then knocked down expression of the transcripts using RNA interference (RNAi) to evaluate potential functions of the Hsps in maintenance of water balance. Fully hydrated females of all three species contained nearly the same amount of water (66-68%), but water loss rates differed among the species, with A. aegypti having the lowest water loss rate (2.6%/h), followed by C. pipiens (3.3%/h), and A. gambiae (5.1%/h). In all three species water could be replaced only by drinking water (or blood). Both A. aegypti and C. pipiens tolerated a loss of 36% of their body water, but A. gambiae was more vulnerable to water loss, tolerating a loss of only 29% of its body water. Dehydration elicited expression of hsp70 in all three species, but only C. pipiens continued to express this transcript during rehydration. Hsp90 was constitutively expressed and expression levels remained fairly constant during dehydration and rehydration, except expression was not noted during rehydration of C. pipiens. Injection of dsRNA to knock down expression of hsp70 (83% reduction) and hsp90 (46% reduction) in A. aegypti did not alter water content or water loss rates, but the dehydration tolerance was lower. Instead of surviving a 36% water loss, females were able to survive only a 28% water loss in response to RNAi directed against hsp70 and a 26% water loss when RNAi was directed against hsp90. These results indicate a critical function for these Hsps in mosquito dehydration tolerance. PMID:19782687

  7. EPR study on gamma-irradiated fruits dehydrated via osmosis

    NASA Astrophysics Data System (ADS)

    Yordanov, N. D.; Aleksieva, K.

    2007-06-01

    The shape and time stability of the electron paramagnetic resonance (EPR) spectra of non- and ?-irradiated papaya, melon, cherry and fig samples dehydrated via osmosis are reported. It is shown that non-irradiated samples are generally EPR silent whereas ?-irradiated exhibit "sugar-like" EPR spectra. The recorded EPR spectra are monitored for a period of 7 months after irradiation (stored at low humidity and in the dark). The results suggest longer period of unambiguous identification of the radiation processing of osmose dehydrated fruits. Therefore, the Protocol EN 13708,2001 issued by CEN is fully applicable for the studied fruit samples.

  8. A bulge-induced dehydration failure mode of nanocomposite hydrogel

    NASA Astrophysics Data System (ADS)

    Tang, Jingda; Yu, Zejun; Sun, Youyi; Pei, Yongmao; Fang, Daining

    2013-10-01

    Since hydrogels are very soft and usually weak in swollen state, they pose unique challenges to traditional mechanical experiments. The mechanical property of nanocomposite poly(N-isopropylacrylamide) hydrogel was characterized by the bulge test in this investigation. A dehydration failure phenomenon of the hydrogel was found and the failure mechanism was presented. A criterion is proposed that when strain reaches the threshold, water molecules migrate out of the polymer networks and the dehydration failure occurs. The critical strain keeps constant for orifices with different diameters. This failure mode can be applied in the controllable release of drugs.

  9. Ductile Deformation of Dehydrating Serpentinite Evidenced by Acoustic Signal Monitoring

    NASA Astrophysics Data System (ADS)

    Gasc, J.; Hilairet, N.; Wang, Y.; Schubnel, A. J.

    2012-12-01

    Serpentinite dehydration is believed to be responsible for triggering earthquakes at intermediate depths (i.e., 60-300 km) in subduction zones. Based on experimental results, some authors have proposed mechanisms that explain how brittle deformation can occur despite high pressure and temperature conditions [1]. However, reproducing microseismicity in the laboratory associated with the deformation of dehydrating serpentinite remains challenging. A recent study showed that, even for fast dehydration kinetics, ductile deformation could take place rather than brittle faulting in the sample [2]. This latter study was conducted in a multi-anvil apparatus without the ability to control differential stress during dehydration. We have since conducted controlled deformation experiments in the deformation-DIA (D-DIA) on natural serpentinite samples at sector 13 (GSECARS) of the APS. Monochromatic radiation was used with both a 2D MAR-CCD detector and a CCD camera to determine the stress and the strain of the sample during the deformation process [3]. In addition, an Acoustic Emission (AE) recording setup was used to monitor the microseismicity from the sample, using piezo-ceramic transducers glued on the basal truncation of the anvils. The use of six independent transducers allows locating the AEs and calculating the corresponding focal mechanisms. The samples were deformed at strain rates of 10-5-10-4 s-1 under confining pressures of 3-5 GPa. Dehydration was triggered during the deformation by heating the samples at rates ranging from 5 to 60 K/min. Before the onset of the dehydration, X-ray diffraction data showed that the serpentinite sustained ~1 GPa of stress which plummeted when dehydration occurred. Although AEs were recorded during the compression and decompression stages, no AEs ever accompanied this stress drop, suggesting ductile deformation of the samples. Hence, unlike many previous studies, no evidence for fluid embrittlement and anticrack generation was found in our experiments. These results suggest that dehydration of serpentinite alone cannot be responsible for intermediate earthquakes. The recovered samples microstructures are currently studied in the SEM and further experiments are planned on partially hydrated samples (i.e., containing olivine), capable of sustaining higher stress levels. 1. Jung, H. and H.W. Green, International Geology Review, 2004. 46(12): p. 1089-1102. 2. Gasc, J., et al., Physics of the Earth and Planetary Interiors, 2011. 189(3-4): p. 121-133. 3. Wang, Y.B., et al., Review of Scientific Instruments, 2003. 74(6): p. 3002-3011.

  10. Enhanced Condensation Heat Transfer

    NASA Astrophysics Data System (ADS)

    Rose, John Winston

    The paper gives some personal observations on various aspects of enhanced condensation heat transfer. The topics discussed are external condensation (horizontal low-finned tubes and wire-wrapped tubes), internal condensation (microfin tubes and microchannels) and Marangoni condensation of binary mixtures.

  11. Condensed phase preparation of 2,3-pentanedione

    DOEpatents

    Miller, Dennis J. (Okemos, MI); Perry, Scott M. (Beaumont, TX); Fanson, Paul T. (Stockbridge, MI); Jackson, James E. (Haslett, MI)

    1998-01-01

    A condensed phase process for the preparation of purified 2,3-pentanedione from lactic acid and an alkali metal lactate is described. The process uses elevated temperatures between about 200.degree. to 360.degree. C. for heating a reaction mixture of lactic acid and an alkali metal lactate to produce the 2,3-pentanedione in a reaction vessel. The 2,3-pentanedione produced is vaporized from the reaction vessel and condensed with water.

  12. Condensed phase preparation of 2,3-pentanedione

    DOEpatents

    Miller, D.J.; Perry, S.M.; Fanson, P.T.; Jackson, J.E.

    1998-11-03

    A condensed phase process for the preparation of purified 2,3-pentanedione from lactic acid and an alkali metal lactate is described. The process uses elevated temperatures between about 200 to 360 C for heating a reaction mixture of lactic acid and an alkali metal lactate to produce the 2,3-pentanedione in a reaction vessel. The 2,3-pentanedione produced is vaporized from the reaction vessel and condensed with water. 5 figs.

  13. Studies toward biomimetic claisen condensation using nucleic acid templates and ribozyme catalysis

    E-print Network

    Ryu, Youngha

    2005-08-29

    condition for decarboxylative Claisen condensation in polyketide biosynthesis was discovered. The reaction of a malonic acid half oxyester with a Nhydroxysuccinmidyl ester forming reagent resulted in self-condensation to provide the corresponding 1...

  14. Mantle wedge infiltrated with saline fluids from dehydration and decarbonation of subducting slab.

    PubMed

    Kawamoto, Tatsuhiko; Yoshikawa, Masako; Kumagai, Yoshitaka; Mirabueno, Ma Hannah T; Okuno, Mitsuru; Kobayashi, Tetsuo

    2013-06-11

    Slab-derived fluids play an important role in heat and material transfer in subduction zones. Dehydration and decarbonation reactions of minerals in the subducting slab have been investigated using phase equilibria and modeling of fluid flow. Nevertheless, direct observations of the fluid chemistry and pressure-temperature conditions of fluids are few. This report describes CO2-bearing saline fluid inclusions in spinel-harzburgite xenoliths collected from the 1991 Pinatubo pumice deposits. The fluid inclusions are filled with saline solutions with 5.1 ± 1.0% (wt) NaCl-equivalent magnesite crystals, CO2-bearing vapor bubbles, and a talc and/or chrysotile layer on the walls. The xenoliths contain tremolite amphibole, which is stable in temperatures lower than 830 °C at the uppermost mantle. The Pinatubo volcano is located at the volcanic front of the Luzon arc associated with subduction of warm oceanic plate. The present observation suggests hydration of forearc mantle and the uppermost mantle by slab-derived CO2-bearing saline fluids. Dehydration and decarbonation take place, and seawater-like saline fluids migrate from the subducting slab to the mantle wedge. The presence of saline fluids is important because they can dissolve more metals than pure H2O and affect the chemical evolution of the mantle wedge. PMID:23716664

  15. Ample Water, Avoiding Dehydration Can Prevent Renal Calculi

    MedlinePLUS

    A Summer Menace Ample Water, Avoiding Dehydration Can Prevent Renal Calculi By Jan Ehrman On the front page... Talk about a summer bummer. They could ... should be drinking at least 12 glasses of water each day, especially during the summer.” kidney stones— ...

  16. Compositional Constraints on Dehydration Embrittlement in Serpentinized Peridotite

    NASA Astrophysics Data System (ADS)

    Xia, G.; Zhang, J.; Green, H. W.

    2012-12-01

    Double seismic zones (DSZ) which have two parallel planes of seismicity separated by 15-40 km are a global feature of subduction zones in the 70-250 km depth range (Brudzinski et al., 2007). While the physical mechanism of lower plane seismicity is still controversial, the leading hypotheses currently are associated with dehydration of antigorite serpentine within the subducting mantle plate (Peacock, 2001; Jung et al., 2004). In this study, we are conducting high-pressure (1-3GPa), high-temperature (720-750 Celsius), deformation experiments on specimens of varying compositions of serpentine plus peridotite in our 4GPa Modified Griggs apparatus. Using samples composed of interlayered thin discs of antigorite and harzburgite, we find that dehydration embrittlement occurs down to less than ~30 vol % antigorite. Interlayered mineralogy was impractical at lower antigorite fractions so we prepared homogeneous mixtures of powders of the two rock types (35-75 ?m grain-size) and "warm" pressed them to a coherent solid with little porosity. Subsequent deformation of these specimens extended the faulting regime to as little as ~8 vol % antigorite. In summary, we find that faulting occurs during dehydration in a wide range of serpentinized peridotite compositions but not during dehydration of nearly pure serpentinite nor nearly pure peridotite. We suggest that the lack of faulting in nearly pure peridotite is a consequence of too little H2O production and the lack of faulting in nearly pure serpentine is due to extensive crystal plasticity.

  17. Textile mill effluent decolorization using crude dehydrated sewage sludge

    Microsoft Academic Search

    H. Dhaouadi; F. M’Henni

    2008-01-01

    Crude dehydrated sewage sludge issued from an urban wastewater treatment plant (High-rate aeration, activated sludge process, Monastir, Tunisia) is used as an adsorbent for the decolorization of a textile mill effluent. The main objective of this work was to evaluate the crude material adsorption capability of the dye contained in wastewater. No treatment to modify any of the adsorbent properties

  18. POULTRY EXCRETA DEHYDRATION AND UTILIZATION: SYSTEM DEVELOPMENT AND DEMONSTRATION

    EPA Science Inventory

    A manure handling and drying system involving caged layers with daily manure collection, air drying, and dehydration in a flash-type dryer has been studied. Objectives of the study were to: (1) Develop a complete manure handling system to maximize pollution control; (2) determine...

  19. Leaf Shrinkage with Dehydration: Coordination with Hydraulic Vulnerability and Drought

    E-print Network

    Sack, Lawren

    simulations of the leaf hydraulic system showed that a reduction of hydraulic conductance of the mesophyll through the hydraulic system. The leaf hydraulic system has two components, which act essentiallyLeaf Shrinkage with Dehydration: Coordination with Hydraulic Vulnerability and Drought Tolerance1[C

  20. DEHYDRATION OF ALCOHOLS VIA PERVAPORATION USING A NOVEL HYDROHILIC MEMBRANE

    EPA Science Inventory

    Pervaporation has emerged as an economically viable alternative technology for the dehydration of organic solvents, removal of organic compounds from water and organic/organic separations. Development of a suitable membrane system with high flux and high selectivity plays a criti...

  1. DEHYDRATION OF ALCOHOLS VIA PREVAPORATION USING A NOVEL HYDROPHILIC MEMBRANE

    EPA Science Inventory

    Pervaporation has emerged as an economically viable alternative technology for the dehydration of organic solvents, removal of organic compounds from water and organic/organic separations. Development of a suitable membrane system with high flux and high selectivity plays a criti...

  2. Thermal dehydration-induced thirst in lithium-treated rats

    Microsoft Academic Search

    Christopher C. Barney; Dorothy M. Kurylo; Justin L. Grobe

    2003-01-01

    Lithium is used as the primary treatment for bipolar disorder but has the common side effects of diuresis and thirst. In the present study, the effects of lithium on water balance responses of male Sprague–Dawley rats to thermal dehydration were examined. Rats ate either unadulterated food or food containing 2 g\\/kg lithium carbonate for 10 days. Then the control and

  3. Science Study Aids 1: Dehydration for Food Preservation.

    ERIC Educational Resources Information Center

    Boeschen, John; And Others

    This publication is the first of a series of seven supplementary investigative materials for use in secondary science classes providing up-to-date research-related investigations. This unit is structured for grades 9 through 12. It is concerned with the osmatic dehydration of fruits. The guide provides students with information about food…

  4. Quality of Chips Produced from Rehydrated Dehydrated Plantain and Banana

    Microsoft Academic Search

    2006-01-01

    This experiment reports the effect of dehydration and rehydration of the physicochemical properties of chips produced from two commercially grown Musa species (plantain and banana) .The fat, ash, crude fibre and protein content in both samples were found to be low and their carbohydrate content were high. The processing of the fresh samples led to observable reduction in proximate composition

  5. The Jewish patient and terminal dehydration: A hospice ethical dilemma

    Microsoft Academic Search

    Janet Bodell; Marie-Ange Weng

    2000-01-01

    Culturally competent nursing care regarding the ethical dilemma of terminal dehydration (withholding or withdrawing food and fluid) for the Jewish hospice patient involves applying the ethical principles of justice, autonomy, beneficence, and nonmaleficence to nursing interventions by identifying outcomes that focus on the high value Jews place on life; avoiding stereotyping as to what it means to be Jewish; knowledge

  6. Mass transfer kinetics of osmotic dehydration of cherry tomato

    Microsoft Academic Search

    Patricia Moreira Azoubel; Fernanda Elizabeth Xidieh Murr

    2004-01-01

    Cherry tomato samples were osmotically dehydrated in different hypertonic NaCl solutions (with or without sucrose) at two different concentrations. Mass transfer kinetics were modelled according to Peleg, Fick and Page equations. The Peleg equation presented the best fitting for water loss and Page model showed the best predictive capacity for salt gain data. The effective diffusivity determined using Fick’s second

  7. Recycled dehydrated lithosphere observed in plume-influenced

    E-print Network

    Langmuir, Charles H.

    Recycled dehydrated lithosphere observed in plume-influenced mid-ocean-ridge basalt Jacqueline Eaby the deep mantle through the subduction and recycling of hydrated oceanic lithosphere. Here we address the question of recycling of water into the deep mantle by characterizing the volatile contents of different

  8. Evaluation of pellets from different industrial processing of dehydrated lucerne in dairy cattle feeding

    Microsoft Academic Search

    G Cozzi; G. M Burato; P Berzaghi; I Andrighetto

    2002-01-01

    The research evaluated three pellets from different industrial processing of dehydrated lucerne. Pre-bloom cut lucerne was dehydrated and pelleted to obtain the Control product. The second pellet was produced by mechanical pressing of the forage before dehydration to extract a juice rich in soluble proteins and carbohydrates used by the poultry feeding industry. This pellet had a higher neutral detergent

  9. Redox state of iron during high-pressure serpentinite dehydration

    NASA Astrophysics Data System (ADS)

    Debret, Baptiste; Bolfan-Casanova, Nathalie; Padrón-Navarta, José Alberto; Martin-Hernandez, Fatima; Andreani, Muriel; Garrido, Carlos J.; López Sánchez-Vizcaíno, Vicente; Gómez-Pugnaire, María Teresa; Muñoz, Manuel; Trcera, Nicolas

    2015-04-01

    The Cerro del Almirez massif (Spain) represents a unique fragment of serpentinized oceanic lithosphere that has been first equilibrated in the antigorite stability field (Atg-serpentinites) and then dehydrated into chlorite-olivine-orthopyroxene (Chl-harzburgites) at eclogite facies conditions during subduction. The massif preserves a dehydration front between Atg-serpentinites and Chl-harzburgites. It constitutes a suitable place to study redox changes in serpentinites and the nature of the released fluids during their dehydration. Relative to abyssal serpentinites, Atg-serpentinites display a low Fe3+/FeTotal(BR) (=0.55) and magnetite modal content (=2.8-4.3 wt%). Micro-X-ray absorption near-edge structure (?-XANES) spectroscopy measurements of serpentines at the Fe-K edge show that antigorite has a lower Fe3+/FeTotal ratio (=0.48) than oceanic lizardite/chrysotile assemblages. The onset of Atg-serpentinites dehydration is marked by the crystallization of a Fe3+-rich antigorite (Fe3+/FeTotal = 0.6-0.75) in equilibrium with secondary olivine and by a decrease in magnetite amount (=1.6-2.2 wt%). This suggests a preferential partitioning of Fe3+ into serpentine rather than into olivine. The Atg-breakdown is marked by a decrease in Fe3+/FeTotal(BR) (=0.34-0.41), the crystallization of Fe2+-rich phases and the quasi-disappearance of magnetite (=0.6-1.4 wt.%). The observation of Fe3+-rich hematite and ilmenite intergrowths suggests that the O2 released by the crystallization of Fe2+-rich phases could promote hematite crystallization and a subsequent increase in fo2 inside the portion of the subducted mantle. Serpentinite dehydration could thus produce highly oxidized fluids in subduction zones and contribute to the oxidization of the sub-arc mantle wedge.

  10. Enhanced Catalysis Activity in a Coordinatively Unsaturated Cobalt-MOF Generated via Single-Crystal-to-Single-Crystal Dehydration.

    PubMed

    Ren, Hai-Yun; Yao, Ru-Xin; Zhang, Xian-Ming

    2015-07-01

    Hydrothermal reaction of Co(NO3)2 and terphenyl-3,2?,5?,3'-tetracarboxyate (H4tpta) generated Co3(OH)2 chains based 3D coordination framework Co3(OH)2(tpta)(H2O)4 (1) that suffered from single-crystal-to-single-crystal dehydration by heating at 160 °C and was transformed into dehydrated Co3(OH)2(tpta) (1a). During the dehydration course, the local coordination environment of part of the Co atoms was transformed from saturated octahedron to coordinatively unsaturated tetrahedron. Heterogenous catalytic experiments on allylic oxidation of cyclohexene show that dehydrated 1a has 6 times enhanced catalytic activity than as-synthesized 1 by using tert-butyl hydroperoxide (t-BuOOH) as oxidant. The activation energy for the oxidation of cylcohexene with 1a catalyst was 67.3 kJ/mol, far below the value with 1 catalysts, which clearly suggested that coordinatively unsaturated Co(II) sites in 1a have played a significant role in decreasing the activation energy. It is interestingly found that heterogeneous catalytic oxidation of cyclohexene in 1a not only gives the higher conversion of 73.6% but also shows very high selectivity toward 2-cyclohexene-1-one (ca. 64.9%), as evidenced in high turnover numbers (ca. 161) based on the open Co(II) sites of 1a catalyst. Further experiments with a radical trap indicate a radical chain mechanism. This work demonstrates that creativity of coordinatively unsaturated metal sites in MOFs could significantly enhance heterogeneous catalytic activity and selectivity. PMID:26046376

  11. Dehydration and crystallization of amorphous calcium carbonate in solution and in air

    PubMed Central

    Ihli, Johannes; Wong, Wai Ching; Noel, Elizabeth H.; Kim, Yi-Yeoun; Kulak, Alexander N.; Christenson, Hugo K.; Duer, Melinda J.; Meldrum, Fiona C.

    2014-01-01

    The mechanisms by which amorphous intermediates transform into crystalline materials are poorly understood. Currently, attracting enormous interest is the crystallization of amorphous calcium carbonate, a key intermediary in synthetic, biological and environmental systems. Here we attempt to unify many contrasting and apparently contradictory studies by investigating this process in detail. We show that amorphous calcium carbonate can dehydrate before crystallizing, both in solution and in air, while thermal analyses and solid-state nuclear magnetic resonance measurements reveal that its water is present in distinct environments. Loss of the final water fraction—comprising less than 15% of the total—then triggers crystallization. The high activation energy of this step suggests that it occurs by partial dissolution/recrystallization, mediated by surface water, and the majority of the particle then crystallizes by a solid-state transformation. Such mechanisms are likely to be widespread in solid-state reactions and their characterization will facilitate greater control over these processes. PMID:24469266

  12. Fluid flux and melting reactions in subduction zones

    NASA Astrophysics Data System (ADS)

    Bouilhol, Pierre; Magni, Valentina; van Hunen, Jeroen; Kaislaniemi, Lars

    2014-05-01

    Understanding the metamorphic reactions that occurs within the slab is a must to constrain subduction zone processes. Slab dehydration reactions ultimately permit the mantle wedge to melt, by lowering its solidus, thus forming arcs above descending slabs. Alternatively the slab crust may cross its solidus in warm hydrated slabs. Moreover, slab dehydration allows chemical fractionation to occur between residual phases and transferred fluid phase, giving arc magmas part of their typical subduction zone chemical characteristics. To better comprehend such complex thermo-chemical open system, we are using a numerical model that reproduces the thermo-mechanical behaviour of a subducting slab and computes the thermodynamic equilibrium paragenesis at each P-T-X conditions of the system. Hence we generate a "paragenetic map" of a subduction system, allowing us to track the fate of water during dehydration and subsequent re-hydration or melting reactions. Here we highlight the role of dehydration and re-hydration reactions occurring in the slab's igneous crust and mantle and the mantle wedge for different slab configuration hence presenting the evolution of a subduction paragenetic map for different regimes. We intend to show the key roles of a) antigorite and chlorite breakdown in the hydrated part of the slab mantle, b) amphibole and lawsonite in the slab crust, and c) the role of amphibole and chlorite in the mantle wedge. Our results show the crucial role of dehydration and re-hydration reactions on slab and mantle wedge melting potential.

  13. Experimental study of trace element release during ultrahigh-pressure serpentinite dehydration

    NASA Astrophysics Data System (ADS)

    Spandler, Carl; Pettke, Thomas; Hermann, Joerg

    2014-04-01

    Subduction of serpentinite is envisaged to play a key role in volatile and element recycling at convergent plate margins, but there is currently little known about the composition of the fluid phase(s) released by devolatilisation of deeply subducted serpentinite. We have performed a series of ultrahigh pressure experiments to examine the phase relations and fluid compositions produced by reaction of a natural serpentinite under sub-arc conditions. We employ a novel technique of forming synthetic fluid inclusions in olivine at run conditions to preserve samples of experimental fluids for subsequent analysis. Our experiments confirm that the breakdown of antigorite and chlorite are the most important fluid-producing reactions from serpentinite at sub-arc depths. For our low CaO/Al2O3 peridotitic composition at 3.5 to 4.0 GPa we find that clinopyroxene reacts out below 750 °C and chlorite breaks down progressively between 700 and 800 °C to form garnet harzburgite. Raman analysis of synthetic fluid inclusions indicates that all experiments contained a single aqueous fluid phase, which - together with a lack of textural or mineralogical evidence for hydrous melting - indicates that the water-saturated solidus for our starting composition is above 900 °C at 4.0 GPa. Element concentrations in the fluid for three experiments were determined in situ via laser ablation ICP-MS of individual fluid inclusions. In general, the fluids are enriched in trace elements compared to the bulk starting material, but particularly so for Li, B, LILE, LREE, and U. Chlorite dehydration fluids have high Li/B, LREE/HREE and Ce/Y due to retention of some B in olivine, and retention of Y and HREE in garnet. Our results indicate that fluids produced by serpentinite dehydration at sub-arc depths may carry some of the slab-derived trace elements required for arc magmatism, and may fractionate key trace element ratios in the dehydrated residues, which in turn may ultimately contribute to the geochemical heterogeneity of mantle-derived magmas.

  14. Improvements in the order, isotropy and electron density of glypican-1 crystals by controlled dehydration

    SciTech Connect

    Awad, Wael [Lund University, Box 124, 221 00 Lund (Sweden); Cairo University, Cairo (Egypt); Svensson Birkedal, Gabriel [Lund University, Biomedical Center A13, 221 84 Lund (Sweden); Thunnissen, Marjolein M. G. M. [Lund University, Box 124, 221 00 Lund (Sweden); Lund University, Box 188, 221 00 Lund (Sweden); Mani, Katrin [Lund University, Biomedical Center A13, 221 84 Lund (Sweden); Logan, Derek T., E-mail: derek.logan@biochemistry.lu.se [Lund University, Box 124, 221 00 Lund (Sweden)

    2013-12-01

    The anisotropy of crystals of glypican-1 was significantly reduced by controlled dehydration using the HC1 device, allowing the building of previously disordered parts of the structure. The use of controlled dehydration for improvement of protein crystal diffraction quality is increasing in popularity, although there are still relatively few documented examples of success. A study has been carried out to establish whether controlled dehydration could be used to improve the anisotropy of crystals of the core protein of the human proteoglycan glypican-1. Crystals were subjected to controlled dehydration using the HC1 device. The optimal protocol for dehydration was developed by careful investigation of the following parameters: dehydration rate, final relative humidity and total incubation time T{sub inc}. Of these, the most important was shown to be T{sub inc}. After dehydration using the optimal protocol the crystals showed significantly reduced anisotropy and improved electron density, allowing the building of previously disordered parts of the structure.

  15. The use of the Ugi four-component condensation

    Microsoft Academic Search

    Stefano Marcaccini; Tomás Torroba

    2007-01-01

    This protocol describes a procedure for the Ugi four-component condensation. It describes the general mechanism as well as the effects of the nature of the components on the Ugi reaction. It also describes the effects of the reaction conditions on the reaction, along with special procedures and workup. The experimental procedure is exemplified by a description of the preparation of

  16. Pore formation during dehydration of a polycrystalline gypsum sample observed and quantified in a time-series synchrotron X-ray micro-tomography experiment

    NASA Astrophysics Data System (ADS)

    Fusseis, F.; Schrank, C.; Liu, J.; Karrech, A.; Llana-Fúnez, S.; Xiao, X.; Regenauer-Lieb, K.

    2012-03-01

    We conducted an in-situ X-ray micro-computed tomography heating experiment at the Advanced Photon Source (USA) to dehydrate an unconfined 2.3 mm diameter cylinder of Volterra Gypsum. We used a purpose-built X-ray transparent furnace to heat the sample to 388 K for a total of 310 min to acquire a three-dimensional time-series tomography dataset comprising nine time steps. The voxel size of 2.2 ?m3 proved sufficient to pinpoint reaction initiation and the organization of drainage architecture in space and time. We observed that dehydration commences across a narrow front, which propagates from the margins to the centre of the sample in more than four hours. The advance of this front can be fitted with a square-root function, implying that the initiation of the reaction in the sample can be described as a diffusion process. Novel parallelized computer codes allow quantifying the geometry of the porosity and the drainage architecture from the very large tomographic datasets (20483 voxels) in unprecedented detail. We determined position, volume, shape and orientation of each resolvable pore and tracked these properties over the duration of the experiment. We found that the pore-size distribution follows a power law. Pores tend to be anisotropic but rarely crack-shaped and have a preferred orientation, likely controlled by a pre-existing fabric in the sample. With on-going dehydration, pores coalesce into a single interconnected pore cluster that is connected to the surface of the sample cylinder and provides an effective drainage pathway. Our observations can be summarized in a model in which gypsum is stabilized by thermal expansion stresses and locally increased pore fluid pressures until the dehydration front approaches to within about 100 ?m. Then, the internal stresses are released and dehydration happens efficiently, resulting in new pore space. Pressure release, the production of pores and the advance of the front are coupled in a feedback loop.

  17. Economical Condensing Turbines? 

    E-print Network

    Dean, J. E.

    1997-01-01

    Steam turbines have long been used at utilities and in industry to generate power. There are three basic types of steam turbines: condensing, letdown and extraction/condensing. • Letdown turbines reduce the pressure of the incoming steam to one...

  18. Condensed Matter Physics

    Microsoft Academic Search

    Michael P. Marder

    2000-01-01

    A modern, unified treatment of condensed matter physics This new work presents for the first time in decades a sweeping review of the whole field of condensed matter physics. It consolidates new and classic topics from disparate sources, teaching \\

  19. Condensation in Microchannels

    Microsoft Academic Search

    Yongping Chen; Mingheng Shi; Ping Cheng; G. P. Peterson

    2008-01-01

    Condensation in microchannels has applications in a wide variety of advanced microthermal devices. Presented here is a review of both experimental and theoretical analyses of condensation in these microchannels, with special attention given to the effects of channel diameter and surface conditions on the flow regimes of condensing flows occurring in these channels. This review suggests that surface tension, rather

  20. Rehydration characteristics of dehydrated West African pepper (Piper guineense) leaves

    PubMed Central

    Okpala, Laura C; Ekechi, Constance A

    2014-01-01

    The rehydration characteristics of dehydrated West African pepper leaves were investigated at hydration temperatures of 28, 60, 70, and 80°C. Four treatments were given to the leaves: blanched and sun dried, unblanched and sun dried, blanched and shade dried, and unblanched and shade dried. The hydration process of the dehydrated leaves was adequately described by the Peleg's equation. As the hydration temperature increased from 28 to 70°C, there was a significant decrease in the Peleg's constant K1, while for most of the leaves the Peleg's constant K2 varied with temperature. Rehydration ratio values ranged from 3.75 in blanched shade dried leaves to 4.26 in unblanched sun dried leaves with the unblanched leaves generally exhibiting higher ratios than the blanched leaves. PMID:25493183

  1. Dehydration and oxidation of cellulose hydrolysis products in acidic solution

    SciTech Connect

    Garves, K.

    1981-01-01

    The dehydration of cotton cellulose in aqueous solutions in the presence of Ac/sub 2/O, AcOH, HCl, H/sub 2/SO/sub 4/ or HBr proceeded by hydrolysis to carbohydrates with acetate groups, followed by conversion to 5-(hydroxymethyl)furfural (I) and then, to levulinic acid (II) accompanied by humic acids. For the formation of I, HCl was a more efficient and selective catalyst than H/sub 2/SO/sub 4/, and the formation of II was promoted by high acid and H/sub 2/O concentrations in the medium. The addition of FeCl/sub 3/ to the dehydration mixture with HCl and continuous distillation led to the isolation of furfural.

  2. Investigations on the cause of electrocardiogram changes during dehydration 

    E-print Network

    Clark, Donald Ray

    1966-01-01

    of Department /Member ember , r ~Member (Member~ danuary f966 FOREWORD AND ACKNOWLEDGMENTS The author wishes to acknowledge the help given in this study by Dr. James McCrady and Mrs. Glenn Householder and especially to Dr. Michael Szabuniewicz for his... of the radiation sickness syndrome of goats. This indicated a possibility that Ihe abnormal electrocardiograms were related not to myocardial dam- age but to the supervening condition of dehydration. In a subsequent experiment by SzabunieWicz and Clark primary...

  3. 30. BUILDING NO. 527, DEHYDRATING PRESSES, LOOKING SOUTH. ALUMINUM NARROWGUAGE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    30. BUILDING NO. 527, DEHYDRATING PRESSES, LOOKING SOUTH. ALUMINUM NARROW-GUAGE GONDOLA CAR IN LEFT BACKGROUND BROUGHT MOISTENED GUN COTTON FROM REST HOUSE (BUILDING NO. 320-B) IN CANS. (ONE OF THESE CANS IS ON UNLOADING PLATFORM RUNNING BESIDE PRESSES). CONTENTS OF CANS WERE UNLOADED INTO PRESSES BY HAND. - Picatinny Arsenal, 500 Area, Powder Factory & Power House, State Route 15 near I-80, Dover, Morris County, NJ

  4. The geometric isomers of conjugated octadecadienoates from dehydrated methyl ricinoleate

    Microsoft Academic Search

    D. R. Body; F. B. Shorland

    1965-01-01

    The dehydration of methyl ricinoleate by heatingin vacuo in the presence of KHSO4 resulted in the formation of the following conjugated octadecadienoates expressed as a percentage of the final product:cis, trans (trans, cis), 14.3;cis, cis, 11.2;trans, trans, 7.3. The isomers contained the double bonds predominantly in the 9,11 position but the possible presence of traces of 8,10\\u000a and other conjugated

  5. Histological structure and commercial dehydration potential of breadfruit

    Microsoft Academic Search

    Roger M. Reeve

    1974-01-01

    The seedless form of breadfruit, unripe and sliced or diced, can be commercially dehydrated either by tunneldrying or by freezedrying.\\u000a The products are adaptable to various culinary vegetable uses. Wastes, such as peel, core, and culls, serve as a highly digestible\\u000a stock feed. Several anatomical features of the fruit pose special problems in preparation and processing. The histology of\\u000a the

  6. Microwave-assisted air dehydration of apple and mushroom

    Microsoft Academic Search

    Tomas Funebo; Thomas Ohlsson

    1998-01-01

    Microwave-assisted hot-air dehydration of apple and mushroom was performed with low-power microwave energy. The purpose of the investigation was to compare hot-air drying and microwave-assisted hot-air drying. The air velocity, the microwave output power and the air temperature were the variables in the experiments. The microwave energy was supplied by either microwave applicators with transverse magnetic (TM) modes as dominant

  7. Stability of idealized condensed phase detonations

    Microsoft Academic Search

    Mark Short; Iana I. Anguelova; Tariq D. Aslam; John B. Bdzil; Andrew K. Henrick; Gary J. Sharpe

    The linear and nonlinear stability of Chapman-Jouguet (CJ) and overdriven detonations of Zeldovich-von Neumann-Doring (ZND) type are examined in the context of the idealized condensed phase (liquid or solid) detonation model. This model includes a two-component mixture (fuel and product), with a one-step irre- versible reaction possessing a rate that is pressure-sensitive (p n ) and has a variable reaction

  8. Mass transfer kinetics during osmotic dehydration of pomegranate arils.

    PubMed

    Mundada, Manoj; Hathan, Bahadur Singh; Maske, Swati

    2011-01-01

    The mass transfer kinetics during osmotic dehydration of pomegranate arils in osmotic solution of sucrose was studied to increase palatability and shelf life of arils. The freezing of the whole pomegranate at -18 °C was carried out prior to osmotic dehydration to increase the permeability of the outer cellular layer of the arils. The osmotic solution concentrations used were 40, 50, 60°Bx, osmotic solution temperatures were 35, 45, 55 °C. The fruit to solution ratio was kept 1:4 (w/w) during all the experiments and the process duration varied from 0 to 240 min. Azuara model and Peleg model were the best fitted as compared to other models for water loss and solute gain of pomegranate arils, respectively. Generalized Exponential Model had an excellent fit for water loss ratio and solute gain ratio of pomegranate arils. Effective moisture diffusivity of water as well as solute was estimated using the analytical solution of Fick's law of diffusion. For above conditions of osmotic dehydration, average effective diffusivity of water loss and solute gain varied from 2.718 × 10(-10) to 5.124 × 10(-10) m(2)/s and 1.471 × 10(-10) to 5.147 × 10(-10) m(2)/s, respectively. The final product was successfully utilized in some nutritional formulations such as ice cream and bakery products. PMID:21535673

  9. Dehydration Influences Mood and Cognition: A Plausible Hypothesis?

    PubMed Central

    Benton, David

    2011-01-01

    The hypothesis was considered that a low fluid intake disrupts cognition and mood. Most research has been carried out on young fit adults, who typically have exercised, often in heat. The results of these studies are inconsistent, preventing any conclusion. Even if the findings had been consistent, confounding variables such as fatigue and increased temperature make it unwise to extrapolate these findings. Thus in young adults there is little evidence that under normal living conditions dehydration disrupts cognition, although this may simply reflect a lack of relevant evidence. There remains the possibility that particular populations are at high risk of dehydration. It is known that renal function declines in many older individuals and thirst mechanisms become less effective. Although there are a few reports that more dehydrated older adults perform cognitive tasks less well, the body of information is limited and there have been little attempt to improve functioning by increasing hydration status. Although children are another potentially vulnerable group that have also been subject to little study, they are the group that has produced the only consistent findings in this area. Four intervention studies have found improved performance in children aged 7 to 9 years. In these studies children, eating and drinking as normal, have been tested on occasions when they have and not have consumed a drink. After a drink both memory and attention have been found to be improved. PMID:22254111

  10. Hypernatraemic dehydration and acute gastro-enteritis in children.

    PubMed

    Abu-Ekteish, F; Zahraa, J

    2002-09-01

    A prospective study was conducted over a 2-year period to detect the effect of feeding practice, in particular the role of artificial milk formulae, in children admitted with hypernatraemic dehydration (serum sodium > or = 150 mmol/L) caused by acute gastro-enteritis, and to record morbidity and mortality in these patients. A control group was selected from infants and children admitted with gastro-enteritis but normal sodium levels. Sixty-seven children aged 18 days to 18 months (mean 6.9 months) were studied and represented 4.6% of all children admitted during the study with acute gastro-enteritis. Their mean serum sodium level was 161 mmol/L, the highest being 194 mmol/L. Twenty-four infants (36%) with hypernatraemic dehydration were on evaporated cow's milk powder compared with ten (15%) in the control group (p < 0.01). Five hypernatraemic infants (7.5%) were breastfed compared with 40 (60%) isonatraemic controls (p < 0.00001). Six children from the hypernatraemic group developed convulsions and two died. Hypernatraemic dehydration remains an important and serious complication in infants with gastro-enteritis in our area. Artificial milk feeding, particularly the use of evaporated cow's milk powder, is a predisposing factor for hypernatraemia in infantile gastro-enteritis. This study emphasises the importance of breast-feeding and the need to educate mothers to avoid giving evaporated cow's milk formulae to babies under 1 year of age if breast-feeding is not possible. PMID:12369489

  11. Ligation of the hairpin ribozyme in cis induced by freezing and dehydration

    PubMed Central

    KAZAKOV, SERGEI A.; BALATSKAYA, SVETLANA V.; JOHNSTON, BRIAN H.

    2006-01-01

    Although reducing the temperature slows most chemical reactions, freezing can stimulate some reactions by mechanisms that are only partially understood. Here we show that freezing stimulates the self-ligation (circularization) of linear forms of the hairpin ribozyme (HPR) containing 2?,3?-cyclic phosphate and 5?-OH termini. Divalent metal ions (M2+) are not required, but monovalent cations and anions at millimolar concentrations can have various effects on this reaction depending on the specific ion. Under optimal conditions, the observed rate of M2+-independent self-ligation reaches a peak (0.04 min?1) at ?10°C with a yield of ?60% after 1 h. In contrast, no ligation occurs either at above 0°C or in solutions that remain unfrozen when supercooled to subzero temperatures. Under freezing conditions, the cleavage–ligation equilibrium strongly favors ligation. Besides freezing, evaporation of the aqueous solvent as well as the presence of ethanol at levels of 40% or above can also induce M2+-independent HPR ligation at 25°C. We argue that partial RNA dehydration, which is a common feature of freezing, evaporation, and the presence of ethanol, is a key factor supporting HPR ligation activity at both above- and below-freezing temperatures. In the context of the RNA world hypothesis, freezing-induced ligation is an attractive mechanism by which complex RNAs could have evolved under conditions in which RNA was relatively protected against degradation. PMID:16495237

  12. Gunion - Nevada`s most innovative geothermal food dehydration facility

    SciTech Connect

    Trexler, D.T.; Taylan, G.; Stewart, M.B.; Baker, S.

    1995-12-31

    The Gunion (garlic and onion) dehydration plant, owned and operated by Integrated Ingredients, a Division of Burns Philp Food, Incorporated, uses geothermal fluids at a temperature of 306{degrees}F to dehydrate 50 to 70-thousand pounds per day of garlic and onions. The geothermal fluids are provided by Empire Farms, who has the rights for development of the resource and is the lease holder of fee land known as the Kosmos Lease. The San Emidio KGRA is located in northern Washoe County, 90 miles north-northeast of Reno, Nevada and 20 miles south of Gerlach, Nevada. Geothermal fluids exit the plant at 242{degrees}F and are piped to an injection well located 3,000 feet south-southwest of the plant. The plant location was selected not only for the geothermal resource, but also for the area`s low relative humidity. Currently, 1100-1200 gpm of geothermal fluids, at an inlet temperature of 302{degrees}F, are sufficient to provide the dryer line with ample BTU`s. Three geothermal wells drilled to depths ranging from 493 to 1817 feet produce fluids ranging in temperature from 266 to 306{degrees}F. One well can easily provide the heat required by the dryer line and will be capable of providing heat for a planned three-fold expansion of the facility. The remaining two wells are used as backup, or may be used for other applications such as soil sterilization. The fluid exiting the plant at 242{degrees}F may be cascaded and used for greenhouses and soil warming in the future. Geothermal heat is also used to dehumidify onions placed in the cold storage facility. The dehydration process takes 5-6 hours to dry the product to a 4.5% moisture content. The dried product is then milled to various sizes from powder to granules. The dehydration plant operates 24 hours/day 7 days a week. Currently 80 people are employed full-time at the plant. The dehydrated onion and garlic are used in condiments, soups, sauces and salad dressing.

  13. Temperature- and pH-dependent aqueous-phase kinetics of the reactions of glyoxal and methylglyoxal with atmospheric amines and ammonium sulfate

    NASA Astrophysics Data System (ADS)

    Sedehi, Nahzaneen; Takano, Hiromi; Blasic, Vanessa A.; Sullivan, Kristin A.; De Haan, David O.

    2013-10-01

    Reactions of glyoxal (Glx) and methylglyoxal (MG) with primary amines and ammonium salts may produce brown carbon and N-containing oligomers in aqueous aerosol. 1H NMR monitoring of reactant losses and product appearance in bulk aqueous reactions were used to derive rate constants and quantify competing reaction pathways as a function of pH and temperature. Glx + ammonium sulfate (AS) and amine reactions generate products containing C-N bonds, with rates depending directly on pH: rate = (70 ± 60) M-1 s-1fAld [Glx]totfAm [Am]tot, where fAld is the fraction of aldehyde with a dehydrated aldehyde functional group, and fAm is the fraction of amine or ammonia that is deprotonated at a given pH. MG + amine reactions generate mostly aldol condensation products and exhibit less pH dependence: rate = 10[(0.36 ± 0.06) × pH - (3.6 ± 0.3)] M-1 s-1fAld [MG]tot [Am]tot. Aldehyde + AS reactions are less temperature-dependent (Ea = 18 ± 8 kJ mol-1) than corresponding amine reactions (Ea = 50 ± 11 kJ mol-1). Using aerosol concentrations of [OH] = 10-12 M, [amine]tot = [AS] = 0.1 M, fGlx = 0.046 and fMG = 0.09, we estimate that OH radical reactions are normally the major aerosol-phase sink for both dicarbonyl compounds. However, reactions with AS and amines together can account for up to 12 and 45% of daytime aerosol-phase glyoxal and methylglyoxal reactivity, respectively, in marine aerosol at pH 5.5. Reactions with AS and amines become less important in acidic or non-marine aerosol, but may still be significant atmospheric sources of brown carbon, imidazoles, and nitrogen-containing oligomers.

  14. The Chemistry of Isocyanides, their MultiComponent Reactions and their Libraries

    Microsoft Academic Search

    I. Ugi; B. Werner; A. Dömling

    2003-01-01

    The first century of isocyanide chemistry, which was then still a rather empty part of Organic Chemistry, began in 1859. In 1958 isocyanides became generally available by dehydration the formylamines. One year later the four component reaction of isocyanides (U-4CR) was introduced. This one-pot reaction is accomplished just by mixing amines, carbonyl compounds, suitable acids and isocyanides. Most chemical reactions

  15. Improvements in the order, isotropy and electron density of glypican-1 crystals by controlled dehydration

    PubMed Central

    Awad, Wael; Svensson Birkedal, Gabriel; Thunnissen, Marjolein M. G. M.; Mani, Katrin; Logan, Derek T.

    2013-01-01

    The use of controlled dehydration for improvement of protein crystal diffraction quality is increasing in popularity, although there are still relatively few documented examples of success. A study has been carried out to establish whether controlled dehydration could be used to improve the anisotropy of crystals of the core protein of the human proteoglycan glypican-1. Crystals were subjected to controlled dehydration using the HC1 device. The optimal protocol for dehydration was developed by careful investigation of the following parameters: dehydration rate, final relative humidity and total incubation time T inc. Of these, the most important was shown to be T inc. After dehydration using the optimal protocol the crystals showed significantly reduced anisotropy and improved electron density, allowing the building of previously dis­ordered parts of the structure. PMID:24311593

  16. Dehydration kinetics of sodium perborate tetrahydrate to monohydrate in a fluidized-bed drier

    Microsoft Academic Search

    Ö ?ahin; A. N. Bulutcu

    1999-01-01

    Dehydration kinetics of sodium perborate tetrahydrate to monohydrate is investigated at four different temperatures between 314.7 and 331K in a controlled fluidized-bed drier. During the dehydration, no thermal decomposition of sodium perborate to sodium metaborate is observed. First-order kinetic behavior in this conversion is proved and the activation energy for dehydration is calculated as 80.18kJ\\/mol. Effect of temperature on the

  17. Dehydration of primary-tertiary acetylenic ? -glycols of the acyclic series

    Microsoft Academic Search

    V. M. Vlasov; T. A. Favorskaya; A. S. Lozhenitsyna; T. S. Kuznetsova

    1966-01-01

    1.Primary-tertiary acetylenicd-glycols undergo dehydration when distilled in the presence of p-toluenesulfonic acid, KHSO4 or concentrated H2SO4, with the formation of enynic alcohols.2.The dehydration of the indicated glycols goes mainly in harmony with the Wagner-Zaitsev rule. If unlike radicals are found attached to the tertiary carbon atom, then the dehydration also goes in part contrary to the rule with the formation

  18. Production of conjugated linoleic acids through KOH-catalyzed dehydration of ricinoleic acid

    Microsoft Academic Search

    Lin Yang; Yu Huang; Han Qing Wang; Zhen-Yu Chen

    2002-01-01

    Production of conjugated linoleic acids (CLA) using castor oil as starting material involves conversion of ricinoleic acid to methyl 12-mesyloxy-octadec-9-enoate (MMOE) followed by dehydration. This process usually uses 1,8-diazabicyclo-(5.4.0)-undec-7-ene (DBU) as an expensive dehydrating reagent. The present study reports that potassium hydroxide (KOH) can serve as a dehydrating reagent in replacement of DBU. The results showed that conversion of MMOE

  19. Kinetics of osmotic dehydration of a highly shrinking vegetable tissue in a salt-free medium

    Microsoft Academic Search

    Harris N. Lazarides; Nicolaos E. Mavroudis

    1996-01-01

    The kinetics of water removal and solute uptake during osmotic dehydration of a highly shrinking vegetable tissue (potato) in a salt-free osmotic medium (corn syrup solids) were studied. Increased temperatures (up to 45 °C) gave highly increased rates of dehydration and net loss of soluble solids ranging between 4.4 and 13.4% of total initial solids. Half dehydration time at 50

  20. Ensuring condensate recovery efficiency.

    PubMed

    Mayoh, Paul

    2012-09-01

    According to steam system specialist, Spirax Sarco, 'condensate contains about a quarter of the energy of the steam from which it came--a significant amount of heat available to an energy centre'. Ensuring that existing condensate recovery systems are as efficient as possible is therefore 'key' to reducing energy centre costs, the company says. Paul Mayoh, product manager, Spirax Sarco, considers ways to ensure that as much condensate as possible is re-used. PMID:23009016

  1. Impact of dehydration on a full body resistance exercise protocol.

    PubMed

    Kraft, Justin A; Green, James M; Bishop, Phillip A; Richardson, Mark T; Neggers, Yasmin H; Leeper, James D

    2010-05-01

    This study examined effects of dehydration on a full body resistance exercise workout. Ten males completed two trials: heat exposed (with 100% fluid replacement) (HE) and dehydration (approximately 3% body mass loss with no fluid replacement) (DEHY) achieved via hot water bath (approximately 39 degrees C). Following HE and DEHY, participants performed three sets to failure (using predetermined 12 repetition maximum) of bench press, lat pull down, overhead press, barbell curl, triceps press, and leg press with a 2-min recovery between each set and 2 min between exercises. A paired t test showed total repetitions (all sets combined) were significantly lower for DEHY: (144.1 +/- 26.6 repetitions) versus HE: (169.4 +/- 29.1 repetitions). ANOVAs showed significantly lower repetitions (approximately 1-2 repetitions on average) per exercise for DEHY versus HE (all exercises). Pre-set rate of perceived exertion (RPE) and pre-set heart rate (HR) were significantly higher [approximately 0.6-1.1 units on average in triceps press, leg press, and approached significance in lat pull down (P = 0.14) and approximately 6-13 b min(-1) on average in bench press, lat pull down, triceps press, and approached significance for overhead press (P = 0.10)] in DEHY versus HE. Session RPE difference approached significance (DEHY: 8.6 +/- 1.9, HE: 7.4 +/- 2.3) (P = 0.12). Recovery HR was significantly higher for DEHY (116 +/- 15 b min(-1)) versus HE (105 +/- 13 b min(-1)). Dehydration (approximately 3%) impaired resistance exercise performance, decreased repetitions, increased perceived exertion, and hindered HR recovery. Results highlight the importance of adequate hydration during full body resistance exercise sessions. PMID:20066432

  2. Thirst perception and drinking in euhydrate and dehydrate human subjects.

    PubMed

    Obika, L F O; Idu, F K; George, G O; Ajayi, O I; Mowoe, R S

    2009-06-01

    Studies on how the body senses the need to correct extracellular and intracellular volumes and ionic concentration changes is relatively scanty. The present studies were designed to determine the effect of oral distilled water (DW) and saline loads, gargling with DW and DW preload on thirst perception (TP) and drinking in euhydrate and dehydrated subjects. The subjects were healthy male volunteers between the ages of 17 and 35 years. Group A subjects were given DW or various concentrations of sodium chloride [NaCl] orally. Subjects in groups B, C and D were dehydrated for 18 hours before the experiment. Group B gargled 500 ml of DW in divided volume of 50 ml at five minutes interval over a period of 50 minutes. Group C gargled with DW and different concentrations of NaCl. Group D were preloaded with four volumes of DW before ad libitum DW intake. TP was rated using the Visual Analogue Scale. Results showed that in Group A, drinking DW reduced TP, suggesting that baseline TP in normal euhydrate subjects is slightly elevated. Drinking DW reduced TP more than drinking NaCl solutions. Gargling resulted in a gradual fall in TP. The decrease in TP was statistically significant after 30 minutes of gargling. Gargling with different concentrations of NaCl solutions resulted in significant reductions in TP in all the groups. There was a significant decrease in TP in the group preloaded with 1000 ml of distilled water at 5 minutes of rehydration. At 20 minutes TP was abolished suggesting that approximately 1000 ml of water was needed for the rehydration. These results show that baseline TP in euhydrates is elevated and that TP increases in dehydrated subjects. Gargling reduces TP, but did not abolish thirst. It is suggested that a fall in plasma osmolality due to drinking may be responsible for abolishing thirst. PMID:19826461

  3. Continuous D-fructose dehydration to 5- hydroxymethylfurfural under mild conditions.

    PubMed

    Aellig, Christof; Hermans, Ive

    2012-09-01

    The dehydration of D-fructose to 5-hydroxymethylfurfural was studied under single-phase conditions in the low boiling solvent 1,4-dioxane at moderate temperatures in the presence of the solid acid-catalyst Amberlyst-15. The reaction was first examined and optimized under batch conditions, where it was found that the yield could be increased up to 75?% by adding small amounts of DMSO. Subsequently, the reaction was performed under continuous flow in a fixed bed reactor. Internal and external mass transfer limitations could be eliminated by changing the particle size and by adjusting the flow rate. Under continuous conditions, the HMF yield could be further increased to 92?%; the space-time yield was found to be 75 times higher compared to the batch case. A long-term stability test (96?h), including solvent regeneration, demonstrated that the catalyst is stable over time. Additionally, it was shown that even small amounts of water have a negative effect on the HMF yield. Overall, the present system shows a good alternative to other systems presented in literature because high space-time yields and selectivities were obtained under relatively mild and continuous conditions. PMID:22761084

  4. Mild Dehydration and Cycling Performance During 5-Kilometer Hill Climbing

    PubMed Central

    Bardis, Costas N.; Kavouras, Stavros A.; Arnaoutis, Giannis; Panagiotakos, Demosthenes B.; Sidossis, Labros S.

    2013-01-01

    Context: Hydration has been shown to be an important factor in performance; however, the effects of mild dehydration during intense cycling are not clear. Objective: To determine the influence of mild dehydration on cycling performance during an outdoor climbing trial in the heat (ambient temperature = 29.0°C ± 2.2°C). Design: Crossover study. Setting: Outdoor. Patients or Other Participants: Ten well-trained, male endurance cyclists (age = 28 ± 5 years, height = 182 ± 0.4 cm, mass = 73 ± 4 kg, maximal oxygen uptake = 56 ± 9 mL·min?1·kg?1, body fat = 23% ± 2%, maximal power = 354 ± 48 W). Intervention(s): Participants completed 1 hour of steady-state cycling with or without drinking to achieve the desired pre-exercise hydration level before 5-km hill-climbing cycling. Participants started the 5-km ride either euhydrated (EUH) or dehydrated by ?1% of body mass (DEH). Main Outcome Measure(s): Performance time, core temperature, sweat rate, sweat sensitivity, and rating of perceived exertion (RPE). Results: Participants completed the 5-km ride 5.8% faster in the EUH (16.6 ± 2.3 minutes) than DEH (17.6 ± 2.9 minutes) trial (t1 = 10.221, P = .001). Postexercise body mass was ?1.4% ± 0.3% for the EUH trial and ?2.2% ± 0.2% for the DEH trial (t1 = 191.384, P < .001). Core temperature after the climb was greater during the DEH (39.2°C ± 0.3°C) than EUH (38.8°C ± 0.2°C) trial (t1 = 8.04, P = .005). Sweat rate was lower during the DEH (0.44 ± 0.16 mg·m?2·s?1) than EUH (0.51 ± 0.16 mg·m?2·s?1) trial (t8 = 2.703, P = .03). Sweat sensitivity was lower during the DEH (72.6 ± 32 g·°C?1·min?1) than EUH (102.6 ± 54.2 g·°C?1·min?1) trial (t8 = 3.072, P = .02). Lastly, RPE after the exercise performance test was higher for the DEH (19.0 ± 1.0) than EUH (17.0 ± 1.0) participants (t9 = ?3.36, P = .008). Conclusions: We found mild dehydration decreased cycling performance during a 5-km outdoor hill course, probably due to greater heat strain and greater perceived intensity. PMID:23952038

  5. Entrapment and condensation of DNA in neutral reverse micelles.

    PubMed Central

    Budker, Vladimir G; Slattum, Paul M; Monahan, Sean D; Wolff, Jon A

    2002-01-01

    DNA condensation and compaction is induced by a variety of condensing agents such as polycations. The present study analyzed the structure of plasmid DNA (DNA) in the small inner space of reverse micelles formed from nonionic surfactants (isotropic phase). Spectroscopic studies indicated that DNA was dissolved in an organic solvent in the presence of a neutral detergent. Fluorescent quenching of ethidium bromide and of rhodamine covalently attached to DNA suggested that the DNA within neutral, reverse micelles was condensed. Circular dichroism indicated that the DNA structure was C form (member of B family) and not the dehydrated A form. Concordantly, NMR experiments indicated that the reverse micelles contained a pool of free water, even at a ratio of water to surfactant (Wo) of 3.75. Electron microscopic analysis also indicated that the DNA was in a ring-like structure, probably toroids. Atomic force microscopic images also revealed small, compact particles after the condensed DNA structures were preserved using an innovative cross-linking strategy. In the lamellar phase, the DNA was configured in long strands that were 20 nm in diameter. Interestingly, such DNA structures, reminiscent of "nanowires," have apparently not been previously observed. PMID:11867469

  6. Osmotic dehydration of fruits and vegetables: a review.

    PubMed

    Yadav, Ashok Kumar; Singh, Satya Vir

    2014-09-01

    The main cause of perishability of fruits and vegetables are their high water content. To increase the shelf life of these fruits and vegetables many methods or combination of methods had been tried. Osmotic dehydration is one of the best and suitable method to increase the shelf life of fruits and vegetables. This process is preferred over others due to their vitamin and minerals, color, flavor and taste retention property. In this review different methods, treatments, optimization and effects of osmotic dehydration have been reviewed. Studied showed that combination of different osmotic agents were more effective than sucrose alone due to combination of properties of solutes. During the experiments it was found that optimum osmosis was found at approximately 40 °C, 40 °B of osmotic agent and in near about 132 min. Pretreatments also leads to increase the osmotic process in fruits and vegetables. Mass transfer kinetics study is an important parameter to study osmosis. Solids diffusivity were found in wide range (5.09-32.77 kl/mol) studied by Fick's laws of diffusion. These values vary depending upon types of fruits and vegetables and osmotic agents. PMID:25190823

  7. Role of pore fluid pressure on transient strength changes and fabric development during serpentine dehydration at mantle conditions: Implications for subduction-zone seismicity

    NASA Astrophysics Data System (ADS)

    Proctor, Brooks; Hirth, Greg

    2015-07-01

    To further investigate the dehydration embrittlement hypothesis and its possible link to subduction-zone seismicity, we conducted deformation experiments on antigorite serpentinite in a Griggs-type apparatus at conditions below and above antigorite stability. Temperature ramps (crossing the antigorite thermal stability) were used in conjunction with a new experimental method that allows fluid produced during dehydration reactions to be drained, partially drained or undrained. During temperature ramps, weakening coupled with transient slip initiated at ? 650 °C, coincident with the predicted phase transition of antigorite to olivine and talc at ? 1 GPa. The weakening-rate and steady-state strength were dependent on drainage conditions; undrained samples weakened over a few minutes and supported the lowest shear stress (? 50 MPa), while drained samples weakened over a few hours and supported the highest shear stress (? 210 MPa). The coefficient of friction (shear stress over normal stress) in drained samples decreased from ?0.4 to ?0.16 after the temperature ramp. The strengths of samples that were first annealed at 700 °C for ? 12 h, then deformed, were similar to those observed in the temperature ramp experiments. Strain localization along fractures occurred in all samples during temperature ramping, regardless of the drainage conditions. However, microstructural observations indicate deformation by ductile mechanisms at higher strain under both undrained and drained conditions. The rheology and microstructures suggest dehydrating serpentinite deforms via semibrittle flow with grain-scale ductile deformation more active at high pore fluid pressures. Our results suggest that earthquakes in serpentinized mantle do not nucleate as a direct result of unstable frictional sliding along fractures generated at the onset of dehydration reactions.

  8. Soft Condensed Matter Biopolymers

    E-print Network

    Schüler, Axel

    Keywords Soft Condensed Matter Biopolymers Cell Elasticity Neuronal Networks Biomimetic properties of membranes and bi- opolymers. Current interests are fo- cused on the plasma membrane condensed matter. In the living cell, this matter is often far from equilib- rium and also behaving in a non

  9. Formation processes of high-dimensional Mo?O frameworks in tetrakis(2-hydroxypropane-1,3-diaminium) hexatriacontamolybdate hydrate (C3H12N2O)4[Mo36O112(H2O)16-m]·nH2O crystals: Solid-phase structural conversions under restricted dehydration conditions

    NASA Astrophysics Data System (ADS)

    Eda, Kazuo; Koduka, Tatsuya; Iriki, Yuichi; Stanley Whittingham, M.

    2013-03-01

    We found that the hexatriacontamolybdate [Mo36O112(H2O)16]8- (?{Mo36}) compound of 1,3-diamino-2-propanol (?OHC3-DA) forms seven structural phases with the formula (?OHC3-DA)4{Mo36}·nH2O. They showed a range of dimensionality: three zero-dimensional (0D), two 1D, and two 2D Mo?O framework structures consisting of {Mo36} anions. Two of the phases have 0D framework structures crystallized in the mother solution. The remaining five phases were obtained when the crystals of these two 0D phases were aged in resin. The dense 2D framework ({Mo36}-nanosheet) of the title compound was formed via solid-phase condensation reactions under restricted dehydration conditions such as in resin-coated crystals, unlike the loose {Mo36}-nanosheet of the (C3?DA)4{Mo36}·nH2O. The formation processes of the related high-dimensional Mo?O frameworks were guided by hydrogen-bonding contacts initially formed between {Mo36} anions in the crystal. There were two different conversion routes: the one starting from the phase consisting of {Mo36} hydrogen-bonded at their head/foot parts lead to the dense 2D nanosheet, while the other originating from the phase consisting of {Mo36} hydrogen-bonded at their trunk parts, to 1D {Mo36}-nanochain with rare triple oxygen bridges. These routes had neither branching nor intercrossing.

  10. Framework for Understanding LENR Processes, Using Conventional Condensed Matter Physics

    Microsoft Academic Search

    Scott R. Chubb

    Conventional Condensed Matter physics provides a unifying framework for understanding Low Energy Nuclear Reactions (LENR's) in solids. In the paper, standard many-body physics techniques are used to illustrate this fact. Specifically, the paper shows that formally the theories by Schwinger, Hagelstein, and Chubb and Chubb (C&C), all can be related to a common set of equations, associated with reaction rate

  11. Experimental dehydration of natural obsidian and estimation of D H 2 O at low water contents

    Microsoft Academic Search

    A. Jambon; Youxue Zhang; E. M. Stolper

    1992-01-01

    Water diffusion experiments were carried out by dehydrating rhyolitic obsidian from Valles Caldera (New Mexico, USA) at 510-980°C. The starting glass wafers contained ~0.114 wt% total water, lower than any glasses previously investigated for water diffusion. Weight loss due to dehydration was measured as a function of experiment duration, which permits determination of mean bulk water diffusivity, . These diffusivities

  12. Dehydration Behaviour of Borax Pentahydrate to Anhydrous Borax by MultiStage Heating in a Fluidized

    Microsoft Academic Search

    Omer S AH; A. Nusret BULUTCU

    In order to optimize the anhydrous borax process in a fluidized bed calcinator, it is absolutely necessary to study the dehydration behaviour of borax pentahydrate. It was found that the basic feature of the dehydration of borax pentahydrate to anhydrous borax is concerned with the conditions employed. The bulk density and sodium borate content of the end product were determined

  13. Simultaneous Infrared Dry-Blanching and Dehydration of apple slices Controlled by Intermittent Heating Mode

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infrared heating controlled by intermittent heating mode was found to be able to achieve simultaneous dry-blanching and dehydration of apple slices with a desirable quality. In order to better understand the performance of intermittent heating for simultaneous dry-blanching and dehydration (SIDBD),...

  14. Rehydration properties of precooked whole beans (Phaseolus vulgaris) dehydrated at room temperature

    Microsoft Academic Search

    J. A. Ulloa; C. R. Bonilla-Sánchez; M. A. Ortíz-Jiménez; P. Rosas-Ulloa; J. C. Ramírez-Ramírez; B. E. Ulloa-Rangel

    2012-01-01

    The aim of this research was to study the rehydration behavior of precooked whole beans (Phaseolus vulgaris) dehydrated at room temperature (25°C) and soaked in water at three temperatures (40, 60, and 80°C). The water absorption of the beans was determined by the gain in weight. The dehydration kinetic at room temperature of the beans was adequately described by the

  15. Effect of blanching\\/osmotic dehydration combined methods on quality and stability of minimally processed strawberries

    Microsoft Academic Search

    J Moreno; A Chiralt; I Escriche; J. A Serra

    2000-01-01

    The combined effect of blanching [steam (S) or microwave (MW)] and osmotic dehydration at atmospheric pressure (OD) or pulsed vacuum treatments (PVOD), on some physiochemical and quality parameters of strawberry (aw, pH, color, firmness, polyphenoloxidase enzyme activity and microstructure), as well as on microbial stability of processed samples, was analyzed. Pulsed vacuum osmotic dehydration with 65 Brix sucrose solution of

  16. Dehydrated Poultry Waste as a Feed for Milking Cows and Growing Sheep1

    Microsoft Academic Search

    J. W. Thomas; Yu Yu; P. TINNIMII-r; H. C. Zindel

    1972-01-01

    Dehydrated feces from caged layers were fed to milking cows to provide 2370 of total dietary protein and 11% of total dry matter intake and to fattening sheep to provide 61 or 90~ of total dietary pro- tein and 25 or 50% of feed intake. Cows fed these dehydrated feces produced more milk than those fed inadequate protein and produced

  17. Infectivity of Poliovirus and Its Nucleic Acid for Dehydrated HeLa Cell Monolayers

    PubMed Central

    Smull, Christine E.; Ludwig, E. H.

    1965-01-01

    Smull, Christine E. (The Geisinger Medical Center, Danville, Pa.), and E. H. Ludwig. Infectivity of poliovirus and its nucleic acid for dehydrated HeLa cell monolayers. J. Bacteriol. 89:52–57. 1965.—A study was made of the infectivity of poliovirus ribonucleic acid (RNA), applied in various diluents, and of poliovirus, on cell monolayers which were washed free from their nutrient medium and allowed to dehydrate for periods up to 3 days prior to inoculation. The plaque formation of poliovirus RNA, applied in isotonic diluent, was greatly increased when assayed on cell monolayers dehydrated for certain periods of time. Conditions are described for bringing about optimal plaque formation by this means, and evidence is presented which strongly indicates that dehydration of the cell is an important factor in the increase in plaque formation of the poliovirus RNA. The plaque formation of poliovirus RNA in certain hypertonic diluents and in a basic protein-containing diluent was also improved with the use of dehydrated cell monolayers, whereas the plaque formation of poliovirus varied very little when assayed on cell monolayers dehydrated for periods up to 2 days. Under certain conditions, the size of the plaques increased as the dehydration time of the cell monolayers was increased. This was true with plaques initiated either by poliovirus or the nucleic acid. Further investigation in these cases revealed that virus production at given times was considerably greater in the dehydrated than in the undried cell monolayers. PMID:14255681

  18. Mass Transfer Modeling and Shrinkage Consideration during Osmotic Dehydration of Fruits and Vegetables

    Microsoft Academic Search

    Hilaire Nahimana; Min Zhang; Arun S. Mujumdar; Zhansheng Ding

    2011-01-01

    During osmotic dehydration of fruits and vegetables, as water and\\/or other substances are removed from the material, shrinkage follows depending on the extent of net mass loss. Mass transfer is usually predicted through modeling. However, common models developed for osmotic dehydration of fruits and vegetables make assumptions that often deviate far from reality, including large heterogeneity, variability and complexity in

  19. Microstructure and Adsorption Characteristics of Mango Chips Obtained by Osmotic Dehydration and Deep Fat Frying

    Microsoft Academic Search

    G. A. P. Torezan; H. C. Menezes; M. E. Katekawa; M. A. Silva

    2007-01-01

    The aim of this work was to evaluate the effects of combined osmotic dehydration and deep fat frying on mango tissue and to determine sorption isotherms for the final products. Fresh, osmotic dehydrated (OD), and OD-fried (chips) slices of Palmer and Tommy Atkins cultivars were examined by scanning electron microscopy. Sorption isotherms of mango chips were obtained using dynamic vapor

  20. Effects of Dehydration on the Viscoelastic Properties of Vocal Folds in Large Deformations

    E-print Network

    Barthelat, Francois

    viscoelastic properties, thereby hampering phonation. The effects of water loss induced by an osmotic pressure, increased significantly with water loss. The effects of dehydration on the viscoelastic properties of vocalEffects of Dehydration on the Viscoelastic Properties of Vocal Folds in Large Deformations Amir K

  1. Dehydration Induced by Bowel Preparation in Older Adults Does Not Result in Cognitive Dysfunction

    Microsoft Academic Search

    Gareth L. Ackland; Jane Harrington; Paul Downie; James W. Holding; Deepak Singh-Ranger; Konstandina Griva; Michael G. Mythen; Stanton P. Newman

    2008-01-01

    BACKGROUND: Postoperative cognitive dysfunction occurs in a proportion of patients after noncardiac surgery. Older patients are particularly vulnerable. We hypoth- esized that dehydration, a common perioperative problem in the elderly, may provoke cognitive dysfunction. We used a clinical scenario free of surgical\\/ anesthetic intervention to determine whether dehydration caused by bowel prepa- ration results in cognitive changes. METHODS: Thirty-eight patients

  2. Selection and Evaluation of Demulsifier Applied to Aging Crude Oil Dehydration

    Microsoft Academic Search

    Wei Lixin; Wang Jinxiu; Wang Zhihua; Hou Jincai

    2010-01-01

    The aging crude oil of oil fields is the oil over a long time and has a large number of breeds such as FeS, which is difficult to deal with. When the complex recovery fluid such as ground raw oil, bailing oil get into the electric dehydration system, the electric dehydration devices have frequent tripping and affect the normal production.

  3. Osmotic dehydration of apples —effects of agitation and raw material characteristics

    Microsoft Academic Search

    Nikolaos E. Mavroudis; Vassilis Gekas; Ingegerd Sjöholm

    1998-01-01

    The effects of agitation and structural differences on osmotic dehydration were investigated. Osmotic dehydration was performed in an agitated vessel at 20 °C using a 50% sucrose solution as the osmotic medium. The impeller's Reynolds number was used for agitation quantification. Samples were separated into inner and outer apple parenchymatic tissue, the intercellular space interconnectivity and aspect ratio (length to

  4. The effect of dehydration on the ultrastructure and cholinesterase activity of the subcommissural organ in the rat

    Microsoft Academic Search

    J. Leonieni; L. Rechardt

    1972-01-01

    Dehydration affected certain cytological features of the subcommissural organ in the albino rat suggesting a strong secretory stimulation of the ependymal and hypendymal cells of this organ in dehydrated animals.

  5. Anhydrobiosis in yeast: influence of calcium and magnesium ions on yeast resistance to dehydration-rehydration.

    PubMed

    Trofimova, Yuliya; Walker, Graeme; Rapoport, Alexander

    2010-07-01

    The influence of calcium and magnesium ions on resistance to dehydration in the yeast, Saccharomyces cerevisiae, was investigated. Magnesium ion availability directly influenced yeast cells' resistance to dehydration and, when additionally supplemented with calcium ions, this provided further significant increase of yeast resistance to dehydration. Gradual rehydration of dry yeast cells in water vapour indicated that both magnesium and calcium may be important for the stabilization of yeast cell membranes. In particular, calcium ions were shown for the first time to increase the resistance of yeast cells to dehydration in stress-sensitive cultures from exponential growth phases. It is concluded that magnesium and calcium ion supplementations in nutrient media may increase the dehydration stress tolerance of S. cerevisiae cells significantly, and this finding is important for the production of active dry yeast preparations for food and fermentation industries. PMID:20487021

  6. Clay hydration/dehydration in dry to water-saturated supercritical CO2: Implications for caprock integrity

    SciTech Connect

    Loring, John S.; Schaef, Herbert T.; Thompson, Christopher J.; Turcu, Romulus VF; Miller, Quin R.; Chen, Jeffrey; Hu, Jian Z.; Hoyt, David W.; Martin, Paul F.; Ilton, Eugene S.; Felmy, Andrew R.; Rosso, Kevin M.

    2013-01-01

    Injection of supercritical CO2 (scCO2) for the geologic storage of carbon dioxide will displace formation water, and the pore space adjacent to overlying caprocks could eventually be dominated by dry to water-saturated scCO2. Wet scCO2 is highly reactive and capable of carbonating and hydrating certain minerals, whereas anhydrous scCO2 can dehydrate water-containing minerals. Because these geochemical processes affect solid volume and thus porosity and permeability, they have the potential to affect the long-term integrity of the caprock seal. In this study, we investigate the swelling and shrinkage of an expandable clay found in caprock formations, montmorillonite (Ca-STx-1), when exposed to variable water-content scCO2 at 50 °C and 90 bar using a combination of in situ probes, including X-ray diffraction (XRD), in situ magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR), and in situ attenuated total reflection infrared spectroscopy (ATR-IR). We show that the extent of montmorillonite clay swelling/shrinkage is dependent not only on water hydration/dehydration, but also on CO2 intercalation reactions. Our results also suggest a competition between water and CO2 for interlayer residency where increasing concentrations of intercalated water lead to decreasing concentrations of intercalated CO2. Overall, this paper demonstrates the types of measurements required to develop fundamental knowledge that will enhance modeling efforts and reduce risks associated with subsurface storage of CO2.

  7. The Biginelli Reaction Is a Urea-Catalyzed Organocatalytic Multicomponent Reaction.

    PubMed

    Puripat, Maneeporn; Ramozzi, Romain; Hatanaka, Miho; Parasuk, Waraporn; Parasuk, Vudhichai; Morokuma, Keiji

    2015-07-17

    The recently developed artificial force induced reaction (AFIR) method was applied to search systematically all possible multicomponent pathways for the Biginelli reaction mechanism. The most favorable pathway starts with the condensation of the urea and benzaldehyde, followed by the addition of ethyl acetoacetate. Remarkably, a second urea molecule catalyzes nearly every step of the reaction. Thus, the Biginelli reaction is a urea-catalyzed multicomponent reaction. The reaction mechanism was found to be identical in both protic and aprotic solvents. PMID:26066623

  8. Skeletal muscle volume following dehydration induced by exercise in heat

    PubMed Central

    2012-01-01

    Background Intracellular skeletal muscle water is redistributed into the extracellular compartment during periods of dehydration, suggesting an associated decline in muscle volume. The purpose of this study was to evaluate skeletal muscle volume in active (knee extensors (KE)) and less active (biceps/triceps brachii, deltoid) musculature following dehydration induced by exercise in heat. Methods Twelve participants (seven men, five women) cycled in the heat under two conditions: (1) dehydration (DHYD) resulting in 3% and 5% losses of estimated total body water (ETBW), which was assessed by changes in body mass, and (2) fluid replacement (FR) where 3% and 5% losses of ETBW were counteracted by intermittent (20 to 30 min) fluid ingestion via a carbohydrate-electrolyte beverage. During both conditions, serum osmolality and skeletal muscle volume (assessed by magnetic resonance imaging) were measured at baseline and at the 3% and 5% ETBW loss measurement points. Results In DHYD, serum osmolality increased at 3% (p?=?0.005) and 5% (p?

  9. Electrolyte vapor condenser

    DOEpatents

    Sederquist, R.A.; Szydlowski, D.F.; Sawyer, R.D.

    1983-02-08

    A system is disclosed for removing electrolyte from a fuel cell gas stream. The gas stream containing electrolyte vapor is supercooled utilizing conventional heat exchangers and the thus supercooled gas stream is passed over high surface area passive condensers. The condensed electrolyte is then drained from the condenser and the remainder of the gas stream passed on. The system is particularly useful for electrolytes such as phosphoric acid and molten carbonate, but can be used for other electrolyte cells and simple vapor separation as well. 3 figs.

  10. Dehydration of oil waste emulsions by means of flocculants

    SciTech Connect

    Gandurina, L.V.; Butseva, L.N.; Shtondina, V.S.

    1995-05-01

    Oil waste emulsions are formed in the course of pumping petroleum crudes and products and are collected from the surfaces of equipment in recirculating water systems and wastewater disposal facilities (oil separators, sand traps, oil traps, holding pits for accidental spills, settlers, ponds, sludge accumulators, and so on). Emulsions are also obtained in the course of cleaning equipment in crude oil desalting and dehydration units. Such emulsions are stable, structurized systems that are very resistant to dewatering by heating and settling in separator tanks. In order to break stabilized emulsions, i.e., in order to ensure complete coalescence of drops when they collide, it is not sufficient to increase the forces of mutual attraction of drops at the moment of collision; in addition, the protective shell must be either destroyed or weakened. Demulsifying agents, or surfactants, will displace the stabilizers. This report is concerned with demulsifier efficiency.

  11. Hypernatraemic dehydration and breast feeding: a population study

    PubMed Central

    Oddie, S; Richmond, S; Coulthard, M

    2001-01-01

    As part of a population based regional review of all neonatal readmissions, the incidence of dehydration with hypernatraemia in exclusively breast fed infants was estimated. All readmissions to hospital in the first month of life during 1998 from a population of 32 015 live births were reviewed. Eight of 907 readmissions met the case definition, giving an incidence of at least 2.5 per 10 000 live births. Serum sodium at readmission varied from 150to 175 mmol/l. One infant had convulsions. The sole explanation for hypernatraemia was unsuccessful breast feeding in all cases. The eight cases are compared with the 65 cases published in the literature since 1979. Presentation, incidence, risk factors, pathophysiology, treatment, and prevention are discussed.?? PMID:11567942

  12. MICROWAVE-ACCELERATED MULTICOMPONENT REACTIONS UNDER SOLVENT-FREE CONDITIONS

    EPA Science Inventory

    The application of microwave-accelerated solventless synthetic protocols in multicomponent (MCC) reactions will be exemplified by several condensation and cyclization reactions including the rapid one-pot assembly of valuable heterocyclic compounds from in situ generated intermed...

  13. Glucose reversion reaction kinetics.

    PubMed

    Pilath, Heidi M; Nimlos, Mark R; Mittal, Ashutosh; Himmel, Michael E; Johnson, David K

    2010-05-26

    The reversion reactions of glucose in mildly acidic aqueous solutions have been studied, and the kinetics of conversion to disaccharides has been modeled. The experiments demonstrate that, at high sugar loadings, up to 12 wt % of the glucose can be converted into reversion products. The reversion products observed are primarily disaccharides; no larger oligosaccharides were observed. Only disaccharides linked to the C1 carbon of one of the glucose residues were observed. The formation of 1,6-linked disaccharides was favored, and alpha-linked disaccharides were formed at higher concentrations than beta-linked disaccharides. This observation can be rationalized on the basis of steric effects. At temperatures >140 degrees C, the disaccharides reach equilibrium with glucose and the reversion reaction competes with dehydration reactions to form 5-hydroxymethylfurfural. As a result, disaccharide formation reaches a maximum at reaction times <10 min and decreases with time. At temperatures <130 degrees C, disaccharide formation reaches a maximum at reaction times >30 min. As expected, disaccharide formation exhibits a second-order dependence upon glucose concentration. Levoglucosan formation is also observed; because it shows a first-order dependence upon glucose concentration, its formation is more significant at low concentrations (10 mg mL(-1)), whereas disaccharide formation dominates at high concentrations (200 mg mL(-1)). Experiments conducted using glucose and its disaccharides were calibrated with readily available standards. The kinetic parameters for hydrolysis of some glucodisaccharides could be compared to published literature values. From these experiments, the kinetics and activation energies for the reversion reactions have been calculated. The rate parameters can be used to model the formation of the disaccharides as a function of reaction time and temperature. A new and detailed picture of the molecular mechanism of these industrially important reversion reactions has been developed. PMID:20429509

  14. Advancing Microwave Technology for Dehydration Processing of Biologics

    PubMed Central

    Cellemme, Stephanie L.; Van Vorst, Matthew; Paramore, Elisha

    2013-01-01

    Our prior work has shown that microwave processing can be effective as a method for dehydrating cell-based suspensions in preparation for anhydrous storage, yielding homogenous samples with predictable and reproducible drying times. In the current work an optimized microwave-based drying process was developed that expands upon this previous proof-of-concept. Utilization of a commercial microwave (CEM SAM 255, Matthews, NC) enabled continuous drying at variable low power settings. A new turntable was manufactured from Ultra High Molecular Weight Polyethylene (UHMW-PE; Grainger, Lake Forest, IL) to provide for drying of up to 12 samples at a time. The new process enabled rapid and simultaneous drying of multiple samples in containment devices suitable for long-term storage and aseptic rehydration of the sample. To determine sample repeatability and consistency of drying within the microwave cavity, a concentration series of aqueous trehalose solutions were dried for specific intervals and water content assessed using Karl Fischer Titration at the end of each processing period. Samples were dried on Whatman S-14 conjugate release filters (Whatman, Maidestone, UK), a glass fiber membrane used currently in clinical laboratories. The filters were cut to size for use in a 13?mm Swinnex® syringe filter holder (Millipore™, Billerica, MA). Samples of 40??L volume could be dehydrated to the equilibrium moisture content by continuous processing at 20% with excellent sample-to-sample repeatability. The microwave-assisted procedure enabled high throughput, repeatable drying of multiple samples, in a manner easily adaptable for drying a wide array of biological samples. Depending on the tolerance for sample heating, the drying time can be altered by changing the power level of the microwave unit. PMID:24835259

  15. Optimum conditions for fabricating superhydrophobic surface on copper plates via controlled surface oxidation and dehydration processes

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Li, Wen; Ma, Fumin; Yu, Zhanlong; Ruan, Min; Ding, Yigang; Deng, Xiangyi

    2013-09-01

    The superhydrophobic surfaces on copper substrate were fabricated by direct oxidation and dehydration processes, and the reaction and modification conditions were optimized. Firstly, the oxidation conditions including the concentrations of K2S2O8 and NaOH, the oxidation time were studied. It is found that the superhydrophobicity would be better if the copper plates were oxidized in 0.06 M K2S2O8 and 3.0 M NaOH solution at 65 °C for 35 min. Then, the modification conditions including modifier concentration and modification time were investigated. The results showed that 5 wt% lauric acid and 1 h modification time were suitable modification conditions for preparing copper-based superhydrophobic surfaces. The surface fabricated under optimized conditions displayed excellent superhydrophobicity of high water contact angle of 161.1° and a low contact angle hysteresis of 2.5°. The surface microstructure and composition of the superhydrophobic surfaces were also characterized by SEM and FT-IR. It is found that the highly concentrated micro/nanostructured sheets and the low surface energy materials on the surface should be responsible for the high superhydrophobicity.

  16. Protection of the photosynthetic apparatus from extreme dehydration and oxidative stress in seedlings of transgenic tobacco.

    PubMed

    Almoguera, Concepción; Prieto-Dapena, Pilar; Personat, José-María; Tejedor-Cano, Javier; Lindahl, Marika; Diaz-Espejo, Antonio; Jordano, Juan

    2012-01-01

    A genetic program that in sunflower seeds is activated by Heat Shock transcription Factor A9 (HaHSFA9) has been analyzed in transgenic tobacco seedlings. The ectopic overexpression of the HSFA9 program protected photosynthetic membranes, which resisted extreme dehydration and oxidative stress conditions. In contrast, heat acclimation of seedlings induced thermotolerance but not resistance to the harsh stress conditions employed. The HSFA9 program was found to include the expression of plastidial small Heat Shock Proteins that accumulate only at lower abundance in heat-stressed vegetative organs. Photosystem II (PSII) maximum quantum yield was higher for transgenic seedlings than for non-transgenic seedlings, after either stress treatment. Furthermore, protection of both PSII and Photosystem I (PSI) membrane protein complexes was observed in the transgenic seedlings, leading to their survival after the stress treatments. It was also shown that the plastidial D1 protein, a labile component of the PSII reaction center, and the PSI core protein PsaB were shielded from oxidative damage and degradation. We infer that natural expression of the HSFA9 program during embryogenesis may protect seed pro-plastids from developmental desiccation. PMID:23227265

  17. Adsorption of the compounds encountered in monosaccharide dehydration in zeolite beta.

    PubMed

    León, Marta; Swift, T Dallas; Nikolakis, Vladimiros; Vlachos, Dionisios G

    2013-06-01

    A comprehensive study of the adsorption of the compounds involved in the reaction of dehydration of fructose to 5-hydroxymethyl furfural (HMF) on the zeolite H-BEA with SiO2/Al2O3 = 18 has been carried out. Furthermore, a method for the estimation of the real adsorption loading from the experimentally measured excess adsorption is developed and applied to calculate the adsorption isotherms both in the case of single-solute and multisolute mixtures. It was found that zeolite H-BEA adsorbs HMF and levulinic acid from water mixtures to greater extent than sugars and formic acid, which prefer to partition in the aqueous phase. HMF and levulinic acid adsorption isotherms could be fitted in a Redlich-Peterson isotherm model, while the adsorption of formic acid is better fitted using the Freundlich model and sugars via the Henry model. Adsorption loadings decreased with increasing temperature (0, 25, and 40 °C), which is characteristic of an exothermic process. From the temperature dependence of the isotherms, the limiting heat of adsorption at zero coverage was determined using van't Hoff equation. Given the importance and the complexity of multicomponent systems, several experiments of adsorption of multisolute solutions have been carried out. In most of the cases, the ideal adsorbed solution theory (IAST) has been proven to satisfactorily predict adsorption from multisolute mixtures using as input the single-solute isotherms. PMID:23642168

  18. Different gene-specific mechanisms determine the ‘revised-response’ memory transcription patterns of a subset of A. thaliana dehydration stress responding genes

    PubMed Central

    Liu, Ning; Ding, Yong; Fromm, Michael; Avramova, Zoya

    2014-01-01

    Plants that have experienced several exposures to dehydration stress show increased resistance to future exposures by producing faster and/or stronger reactions, while many dehydration stress responding genes in Arabidopsis thaliana super-induce their transcription as a ‘memory’ from the previous encounter. A previously unknown, rather unusual, memory response pattern is displayed by a subset of the dehydration stress response genes. Despite robustly responding to a first stress, these genes return to their initial, pre-stressed, transcript levels during the watered recovery; surprisingly, they do not respond further to subsequent stresses of similar magnitude and duration. This transcriptional behavior defines the ‘revised-response’ memory genes. Here, we investigate the molecular mechanisms regulating this transcription memory behavior. Potential roles of abscisic acid (ABA), of transcription factors (TFs) from the ABA signaling pathways (ABF2/3/4 and MYC2), and of histone modifications (H3K4me3 and H3K27me3) as factors in the revised-response transcription memory patterns are elucidated. We identify the TF MYC2 as the critical component for the memory behavior of a specific subset of MYC2-dependent genes. PMID:24744238

  19. Different gene-specific mechanisms determine the 'revised-response' memory transcription patterns of a subset of A. thaliana dehydration stress responding genes.

    PubMed

    Liu, Ning; Ding, Yong; Fromm, Michael; Avramova, Zoya

    2014-05-01

    Plants that have experienced several exposures to dehydration stress show increased resistance to future exposures by producing faster and/or stronger reactions, while many dehydration stress responding genes in Arabidopsis thaliana super-induce their transcription as a 'memory' from the previous encounter. A previously unknown, rather unusual, memory response pattern is displayed by a subset of the dehydration stress response genes. Despite robustly responding to a first stress, these genes return to their initial, pre-stressed, transcript levels during the watered recovery; surprisingly, they do not respond further to subsequent stresses of similar magnitude and duration. This transcriptional behavior defines the 'revised-response' memory genes. Here, we investigate the molecular mechanisms regulating this transcription memory behavior. Potential roles of abscisic acid (ABA), of transcription factors (TFs) from the ABA signaling pathways (ABF2/3/4 and MYC2), and of histone modifications (H3K4me3 and H3K27me3) as factors in the revised-response transcription memory patterns are elucidated. We identify the TF MYC2 as the critical component for the memory behavior of a specific subset of MYC2-dependent genes. PMID:24744238

  20. Mechanism of dropwise condensation

    E-print Network

    Umur, Aydin

    1963-01-01

    From a study of surface phenomena, information is obtained about conditions under which net condensation can occur. An experimental examination of the surface, using an optical method capable of detecting thin films of ...

  1. Transient nucleation in condensed systems

    NASA Technical Reports Server (NTRS)

    Kelton, K. F.; Greer, A. L.; Thompson, C. V.

    1983-01-01

    Using classical nucleation theory we consider transient nucleation occurring in a one-component, condensed system under isothermal conditions. We obtain an exact closed-form expression for the time dependent cluster populations. In addition, a more versatile approach is developed: a numerical simulation technique which models directly the reactions by which clusters are produced. This simulation demonstrates the evolution of cluster populations and nucleation rate in the transient regime. Results from the simulation are verified by comparison with exact analytical solutions for the steady state. Experimental methods for measuring transient nucleation are assessed, and it is demonstrated that the observed behavior depends on the method used. The effect of preexisting cluster distributions is studied. Previous analytical and numerical treatments of transient nucleation are compared to the solutions obtained from the simulation. The simple expressions of Kashchiev are shown to give good descriptions of the nucleation behavior.

  2. Metabolic dysfunction and unabated respiration precede the loss of membrane integrity during dehydration of germinating radicles.

    PubMed

    Leprince, O; Harren, F J; Buitink, J; Alberda, M; Hoekstra, F A

    2000-02-01

    This study shows that dehydration induces imbalanced metabolism before loss of membrane integrity in desiccation-sensitive germinated radicles. Using a photoacoustic detection system, responses of CO(2) emission and fermentation to drying were analyzed non-invasively in desiccation-tolerant and -intolerant radicles of cucumber (Cucumis sativa) and pea (Pisum sativum). Survival after drying and a membrane integrity assay showed that desiccation tolerance was present during early imbibition and lost in germinated radicles. However, tolerance could be re-induced in germinated cucumber radicles by incubation in polyethylene glycol before drying. Tolerant and polyethylene glycol (PEG)-induced tolerant radicles exhibited a much-reduced CO(2) production before dehydration compared with desiccation-sensitive radicles. This difference was maintained during dehydration. In desiccation-sensitive tissues, dehydration induced an increase in the emission of acetaldehyde and ethanol that peaked well before the loss of membrane integrity. Acetaldehyde emission from sensitive radicles was significantly reduced when dehydration occurred in 50% O(2) instead of air. Acetaldehyde/ethanol were not detected in dehydrating tolerant radicles of either species or in polyethylene glycol-induced tolerant cucumber radicles. Thus, a balance between down-regulation of metabolism during drying and O(2) availability appears to be associated with desiccation tolerance. Using Fourier transform infrared spectroscopy, acetaldehyde was found to disturb the phase behavior of phospholipid vesicles, suggesting that the products resulting from imbalanced metabolism in seeds may aggravate membrane damage induced by dehydration. PMID:10677452

  3. Ozone fumigation for safety and quality of wine grapes in postharvest dehydration.

    PubMed

    Botondi, Rinaldo; De Sanctis, Federica; Moscatelli, Niccolò; Vettraino, Anna Maria; Catelli, Cesare; Mencarelli, Fabio

    2015-12-01

    This paper proposes postharvest ozone fumigation (as a method) to control microorganisms and evaluate the effect on polyphenols, anthocyanins, carotenoids and cell wall enzymes during the grape dehydration for wine production. Pignola grapes were ozone-treated (1.5g/h) for 18h (A=shock treatment), then dehydrated or ozone-treated (1.5g/h) for 18h and at 0.5g/h for 4h each day (B=long-term treatment) during dehydration. Treatment and dehydration were performed at 10°C. No significant difference was found for total carotenoid, total phenolic and total anthocyanin contents after 18h of O3 treatment. A significant decrease in phenolic and anthocyanin contents occurred during treatment B. Also carotenoids were affected by B ozone treatment. Pectin methylesterase (PME) and polygalacturonase (PG) activities were higher in A-treated grapes during dehydration. Finally, ozone reduced fungi and yeasts by 50%. Shock ozone fumigation (A treatment) before dehydration can be used to reduce the microbial count during dehydration without affecting polyphenol and carotenoid contents. PMID:26041242

  4. Effects of dehydration on the viscoelastic properties of vocal folds in large deformations.

    PubMed

    Miri, Amir K; Barthelat, François; Mongeau, Luc

    2012-11-01

    Dehydration may alter vocal fold viscoelastic properties, thereby hampering phonation. The effects of water loss induced by an osmotic pressure potential on vocal fold tissue viscoelastic properties were investigated. Porcine vocal folds were dehydrated by immersion in a hypertonic solution, and quasi-static and low-frequency dynamic traction tests were performed for elongations of up to 50%. Digital image correlation was used to determine local strains from surface deformations. The elastic modulus and the loss factor were then determined for normal and dehydrated tissues. An eight-chain hyperelastic model was used to describe the observed nonlinear stress-stretch behavior. Contrary to the expectations, the mass history indicated that the tissue absorbed water during cyclic extension when submerged in a hypertonic solution. During loading history, the elastic modulus was increased for dehydrated tissues as a function of strain. The response of dehydrated tissues was much less affected when the load was released. This observation suggests that hydration should be considered in micromechanical models of the vocal folds. The internal hysteresis, which is often linked to phonation effort, increased significantly with water loss. The effects of dehydration on the viscoelastic properties of vocal fold tissue were quantified in a systematic way. A better understanding of the role of hydration on the mechanical properties of vocal fold tissue may help to establish objective dehydration and phonotrauma criteria. PMID:22483778

  5. Thirst perception in dehydrated sickle cell disease patients in steady state.

    PubMed

    Ozoene, J O; Enosolease, M E; Ajayi, O I; Agoreyo, F O; Obika, L F O

    2009-12-01

    Liberal fluid intake is one of the key management strategies in sickle cell anaemia [SCA] patients in steady state, but less work has been done on the desire of patients to drink water. Using the Visual Analogue Scale we studied thirst perception [TP] in 20 euhydrated SCA patients and 28 control [HbA] subjects, as well as during dehydration in 13 SCA patients and 9 HbA subjects. Serum and urine samples were collected and analyzed for Na, K ions, creatinine concentrations and haematocrit and specific gravity of urine were determined. During euhydration, TP was significantly [P<0.05] higher in male SCA patients compared to the HbA subjects. In females, TP in SCA patient was not statistically significant compared with HbA subjects. After 13 hours of dehydration, TP was significantly [P<0.05] reduced in female. While dehydration increased TP in HbA subjects, it reduced TP in SCA patients. Fluid intakes after dehydration in SCA patients were not significantly different from the control HbA subjects in both male and female. It can be concluded that female SCA patients do not have normal response to dehydration with regards to TP after a period of dehydration. Since dehydration stimulates the release of vasoactive hormones like vasopressin, this may explain why female patients are less prone to crisis than their male counterparts. PMID:20234751

  6. Dehydration Behavior of Metapelites and Metabasites at Very low to low Grade Metamorphic Conditions

    NASA Astrophysics Data System (ADS)

    Massonne, H.; Willner, A. P.

    2007-12-01

    Thermodynamic calculations have been undertaken in the system Na-Ca-K-Fe-Mg-Al-Si-Ti-H-O with the PERPLE_X software package (Connolly, 1990 and updates) for a better understanding of the dehydration behavior of metapelites and metabasites during prograde metamorphism. To obtain reasonable results for the temperature range 150-450° C at pressures up to 25 kbar, the subsequent solid solution models were introduced being compatible with the applied thermodynamic data set of Holland & Powell (1998 and updates): a three component model for Mg-Fe2+-Fe3+-pumpellyite, a two component model for Fe2+-Mg- stilpnomelane, a four component amphibole model (tremolite - Fe2+-tremolite - glaucophane - Mg- riebeckite), and a four component Na-pyroxene model (acmite - jadeite - diopside - hedenbergite). The water contents released by prograde metamorphism up to 450° C from MORB and psammopelitic compositions on top of oceanic crust, were obtained by calculating P-T pseudosections. Metabasite contains 6-7 wt% H2O bound to minerals at 150° C depending on the oxidation state. Along geotherms lower than 7° C/km typical for young subduction zones, no water is released up to 400° C. However, reduction of the rock causes release of small amounts of water. Metapsammopelitic rocks also store about 6 wt% H2O in minerals at 150° C. Considerable amounts of water are liberated by mineral reactions already in the temperature range 150-250° C also at the above mentioned low geotherms. This behavior determines the rheological characteristics of the upper oceanic crust during early subduction. If water is exclusively released in the sedimentary portion of the downgoing crust only this material gets weakened to be scraped off to form accretionary wedges. At geotherms of 15-20° C/km both lithologies show significant dehydration at very low metamorphic grade. For instance, in cold frontal paleoaccretionary prisms of the Chilean Coastal Cordillera metapelites by far dominate whereas in hotter basal accretionary prisms both low grade basic oceanic crust and continental sediments occur. We also hypothesize that accretionary wedge complexes with a clear dominance of sediments should not have formed in hot subduction zones typical for Precambrian Earth.

  7. (1) H nuclear magnetic resonance (NMR) as a tool to measure dehydration in mice.

    PubMed

    Li, Matthew; Vassiliou, Christophoros C; Colucci, Lina A; Cima, Michael J

    2015-08-01

    Dehydration is a prevalent pathology, where loss of bodily water can result in variable symptoms. Symptoms can range from simple thirst to dire scenarios involving loss of consciousness. Clinical methods exist that assess dehydration from qualitative weight changes to more quantitative osmolality measurements. These methods are imprecise, invasive, and/or easily confounded, despite being practiced clinically. We investigate a non-invasive, non-imaging (1) H NMR method of assessing dehydration that attempts to address issues with existing clinical methods. Dehydration was achieved by exposing mice (n?=?16) to a thermally elevated environment (37?°C) for up to 7.5?h (0.11-13% weight loss). Whole body NMR measurements were made using a Bruker LF50 BCA-Analyzer before and after dehydration. Physical lean tissue, adipose, and free water compartment approximations had NMR values extracted from relaxation data through a multi-exponential fitting method. Changes in before/after NMR values were compared with clinically practiced metrics of weight loss (percent dehydration) as well as blood and urine osmolality. A linear correlation between tissue relaxometry and both animal percent dehydration and urine osmolality was observed in lean tissue, but not adipose or free fluids. Calculated R(2) values for percent dehydration were 0.8619 (lean, P?dehydration in live animals. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26123278

  8. Condensate System Troubleshooting and Optimization 

    E-print Network

    Jenkins, B. V.

    1983-01-01

    , some of the carbon dioxide dissolves in the conden sate. This forms carbonic acid. Carbonic acid, being a weak acid, will cause four characteristic problems: The pH of the condensate will drop Dissolved iron content of the condensate... will increase Total dissolved solids content of the condensate will also increase A trough-like thinning of the bottom of the condensate pipe occurs. (Fig. 1) Figure 1 - Carbonic Acid Attack on Condensate Piping What is the impact? Iron is dissolved...

  9. Pore formation during dehydration of polycrystalline gypsum observed and quantified in a time-series synchrotron radiation based X-ray micro-tomography experiment

    NASA Astrophysics Data System (ADS)

    Fusseis, F.; Schrank, C.; Liu, J.; Karrech, A.; Llana-Fúnez, S.; Xiao, X.; Regenauer-Lieb, K.

    2011-10-01

    We conducted an in-situ X-ray micro-computed tomography heating experiment at the Advanced Photon Source (USA) to dehydrate an unconfined 2.3 mm diameter cylinder of Volterra Gypsum. We used a purpose-built X-ray transparent furnace to heat the sample to 388 K for a total of 310 min to acquire a three-dimensional time-series tomography dataset comprising nine time steps. The voxel size of 2.2 ?m3 proved sufficient to pinpoint reaction initiation and the organization of drainage architecture in space and time. We observed that dehydration commences across a narrow front, which propagates from the margins to the centre of the sample in more than four hours. The advance of this front can be fitted with a square-root function, implying that the initiation of the reaction in the sample can be described as a diffusion process. Novel parallelized computer codes allow quantifying the geometry of the porosity and the drainage architecture from the very large tomographic datasets (6.4 × 109 voxel each) in unprecedented detail. We determined position, volume, shape and orientation of each resolvable pore and tracked these properties over the duration of the experiment. We found that the pore-size distribution follows a power law. Pores tend to be anisotropic but rarely crack-shaped and have a preferred orientation, likely controlled by a pre-existing fabric in the sample. With on-going dehydration, pores coalesce into a single interconnected pore cluster that is connected to the surface of the sample cylinder and provides an effective drainage pathway. Our observations can be summarized in a model in which gypsum is stabilized by thermal expansion stresses and locally increased pore fluid pressures until the dehydration front approaches to within about 100 ?m. Then, the internal stresses are released and dehydration happens efficiently, resulting in new pore space. Pressure release, the production of pores and the advance of the front are coupled in a feedback loop. We discuss our findings in the context of previous studies.

  10. A refractory Ca–SiO–H 2–O 2 vapor condensation experiment with implications for calciosilica dust transforming to silicate and carbonate minerals

    Microsoft Academic Search

    Frans J. M. Rietmeijer; Aurora Pun; Yuki Kimura; Joseph A. Nuth

    2008-01-01

    Condensates produced in a laboratory condensation experiment of a refractory Ca–SiO–H2–O2 vapor define four specific and predictable deep metastable eutectic calciosilica compositions. The condensed nanograins are amorphous solids, including those with the stoichiometric CaSiO3 pyroxene composition. In evolving dust-condensing astronomical environments they will be highly suitable precursors for thermally supported, dust-aging reactions whereby the condensates form more complex refractory silicates,

  11. Thermal dehydration reactions characterized by combined measurements of electrical conductivity and elastic wave velocities

    Microsoft Academic Search

    T. Popp; H. Kern

    1993-01-01

    Combined laboratory measurements of seismic velocities and electrical conductivity as a function of PT and drainage conditions have been performed on various rocks containing hydrous minerals. This paper presents experimental results for evaporite rocks containing gypsum (CaSO4 x 2H2O) and carnallite (KMgCl3 x 6H2O) and for serpentinite. The experiments on the evaporite rocks were carried out in a triaxial cell

  12. Conversion of isoamyl alcohol over acid catalysts: Reaction dependence on nature of active centers

    SciTech Connect

    Babu, G.P.; Murthy, R.S.; Krishnan, V. [Hindustan Lever Research Centre, Bombay (India)] [Hindustan Lever Research Centre, Bombay (India)

    1997-02-01

    Acid catalysts are known to catalyze the dehydration of alcohols. In addition some oxide catalysts with basic properties have also been shown to play an important role in such dehydration reactions. The dehydration of aliphatic alcohols to olefins has been studied in detail using alumina silica-alumina and zeolite catalysts. The olefin products further undergo isomerization in presence of acidic sites. The reaction of isoamyl alcohol on catalytic surfaces has not been investigated in greater detail. The dehydration of isoamyl alcohol is of considerable interest in fine chemicals. Isoamyl alcohol may also undergo dehydrogenation as observed in the case of n-butanol. The scope of the present work is to identify the nature of the active sites selective for dehydration and dehydrogenation of isoamyl alcohol and to modify the active sites to promote isomerization of dehydrated products. Four catalytic surfaces on which the acidic strength can be varied, as well as selectively suppressed, are chosen for this study. 17 refs., 1 fig., 3 tabs.

  13. Trace element transport during dehydration processes in the subducted oceanic crust: 1. Experiments and implications for the origin of ocean island basalts

    Microsoft Academic Search

    Tetsu Kogiso; Yoshiyuki Tatsumi; Satoshi Nakano

    1997-01-01

    Dehydration experiments on natural amphibolite have been carried out under upper mantle P\\/T conditions, in order to examine transportation of trace elements during dehydration processes in the subducted oceanic lithosphere. Pb, Nd, and Rb are more readily transported by aqueous fluids during amphibolite dehydration than U-Th, Sm, and Sr, respectively. The results indicates that the dehydration of subducted oceanic crust

  14. Dissolution and condensation kinetics of silica in alkaline solution

    SciTech Connect

    Thornton, S.D.; Radke, C.J.

    1985-03-01

    This paper addresses the viability of soluble silicates reducing hydroxide consumption by siliceous rock reactions. By utilizing a convenient differential rate method, new experimental kinetic data is obtained for the dissolution/condensation rates of quartz at 23 degrees C over the pH range from 11 to 12 and in one molar sodium chloride. The role of added silicates is studied from zero solution concentration to considerably above the solubility limit. A molecular dissolution/condensation reaction scheme is proposed, based on equilibrium absorption of unionized silicic acid. A mathematical model is developed which agrees quite well with the measured kinetic rate data.

  15. An Efficient one-pot Biginelli condensation of aliphatic aldehydes catalyzed by zinc bromide under solvent-free conditions.

    PubMed

    Yu, Yang; Liu, Di; Liu, Chunsheng; Jiang, Heng; Luo, Genxiang

    2007-01-01

    Zinc bromide catalyzes the three component condensation reaction of an aldehyde, urea, and beta-ketoester or beta-diketone under solvent-free conditions to afford the corresponding dihydropyrimidinones (DHPMs) with moderate to high yields in short reaction time. The present method is very effective for the Biginelli condensation of aliphatic aldehydes. PMID:17849292

  16. Oxidation, Reduction, and Condensation of Alcohols over (MO3)3 (M=Mo, W) Nanoclusters

    SciTech Connect

    Fang, Zongtang; Li, Zhenjun; Kelley, Matthew S.; Kay, Bruce D.; Li, Shenggang; Hennigan, Jamie M.; Rousseau, Roger J.; Dohnalek, Zdenek; Dixon, David A.

    2014-10-02

    The reactions of deuterated methanol, ethanol, 1-propanol, 1-butanol, 2-propanol, 2-butanol and t-butanol over cyclic (MO3)3 (M = Mo, W) clusters were studied experimentally with temperature programmed desorption (TPD) and theoretically with coupled cluster CCSD(T) theory and density functional theory. The reactions of two alcohols per M3O9 cluster are required to provide agreement with experiment for D2O release, dehydrogenation and dehydration. The reaction begins with the elimination of water by proton transfers and forms an intermediate dialkoxy species which can undergo further reaction. Dehydration proceeds by a ? hydrogen transfer to a terminal M=O. Dehydrogenation takes place via an ? hydrogen transfer to an adjacent MoVI = O atom or a WVI metal center with redox involved for M = Mo and no redox for M = W. The two channels have comparable activation energies. H/D exchange to produce alcohols can take place after olefin is released or via the dialkoxy species depending on the alcohol and the cluster. The Lewis acidity of the metal center with WVI being larger than MoVI results in the increased reactivity of W3O9 over Mo3O9 for dehydrogenation and dehydration.

  17. A Kinetic Study of the Dehydrations of the Alums KCr(SO4)2. 12H2O and KAl(SO4)2. 12H2O

    Microsoft Academic Search

    Andrew K. Galwey; Giulio G. T. Guarini

    1993-01-01

    A kinetic study of the dehydrations of the alums KCr(SO4)2. 12H2O and KAl(SO4)2. 12H2O in water vapour atmospheres is reported. The product-yield-time data are described by the Avrami-Erofe'ev (n = 2) and contracting cube equations. The observed kinetic behaviour differed from expectation for this reaction, which is known to proceed through the growth of three-dimensional nuclei. The retention of the

  18. Liquid-phase and vapor-phase dehydration of organic/water solutions

    DOEpatents

    Huang, Yu (Palo Alto, CA); Ly, Jennifer (San Jose, CA); Aldajani, Tiem (San Jose, CA); Baker, Richard W. (Palo Alto, CA)

    2011-08-23

    Processes for dehydrating an organic/water solution by pervaporation or vapor separation using fluorinated membranes. The processes are particularly useful for treating mixtures containing light organic components, such as ethanol, isopropanol or acetic acid.

  19. Dehydration and Denitrification in the Arctic Polar Vortex During the 1995-1996 Winter

    NASA Technical Reports Server (NTRS)

    Hintsa, E. J.; Newman, P. A.; Jonsson, H. H.; Webster, C. R.; May, R. D.; Herman, R. L.; Lait, L. R.; Schoeberl, M. R.; Elkins, J. W.; Wamsley, P. R.; Dutton, G. S.; Bui, T. P.; Kohn, D. W.; Anderson, J. G.

    1998-01-01

    Dehydration of more than 0.5 ppmv water was observed between 18 and 19 km (0-450-465 K) at the edge of the Arctic polar vortex on February 1, 1996. More than half the reactive nitrogen (NO(y)) had also been removed, with layers of enhanced NO(y) at lower altitudes. Back trajectory calculations show that air parcels sampled inside the vortex had experienced temperatures as low as 188 K within the previous 12 days, consistent with a small amount of dehydration. The depth of the dehydrated layer (approximately 1 km) and the fact that trajectories passed through the region of ice saturation in one day imply selective growth of a small fraction of particles to sizes large enough (>10 microns) to be irreversibly removed on this timescale. Over 25% of the Arctic vortex in a 20-30 K range of 0 is estimated to have been dehydrated in this event.

  20. Dehydration and Denitrification in the Arctic Polar Vortex During the 1995-1996 Winter

    NASA Technical Reports Server (NTRS)

    Hintsa, E. J.; Newman, P. A.; Jonsson, H. H.; Webster, C. R.; May, R. D.; Herman, R. L.; Lait, L. R.; Schoeberl, M. R.; Elkins, J. W.; Wamsley, P. R.; Dutton, G. S.; Bui, T. P.; Kohn, D. W.; Anderson, J. G.

    1998-01-01

    Dehydration of more than 0.5 ppmv water was observed between 18 and 19 km (theta about 450-465 K) at the edge of the Arctic polar vortex on February 1, 1996. More than half the reactive nitrogen (NO(sub y)) had also been removed, with layers of enhanced (sub y) at lower altitudes. Back trajectory calculations show that air parcels sampled inside the vortex had experienced temperatures as low as 188 K within the previous 12 days, consistent with a small amount of dehydration. The depth of the dehydrated layer (about 1 km) and the fact that trajectories passed through the region of ice saturation in one day imply selective growth of a small fraction of particles to sizes large enough (>10 micron) to be irreversibly removed on this timescale. Over 25% of the Arctic vortex in a 20-30 K range of theta is estimated to have been dehydrated in this event.

  1. Dehydration and Denitrification in the Arctic Polar Vortex During the 1995-1996 Winter

    NASA Technical Reports Server (NTRS)

    Hintsa, E. J.; Newman, P. A.; Jonsson, H. H.; Webster, C. R.; May, R. D.; Herman, R. L.; Lait, L. R.; Schoeberl, M. R.; Elkins, J. W.; Wamsley, P. R.; Dutton, G. S.; Bui, T. P.; Kohn, D. W.; Anderson, J. G.

    1998-01-01

    Dehydration of more than 0.5 ppmv water was observed between 18 and 19 km (theta approximately 450-465 K) at the edge of the Arctic polar vortex on February 1, 1996. More than half the reactive nitrogen (NO(y)) had also been removed, with layers of enhanced NO(y) at lower altitudes. Back trajectory calculations show that air parcels sampled inside the vortex had experienced temperatures as low as 188 K within the previous 12 days, consistent with a small amount of dehydration. The depth of the dehydrated layer (approximately 1 km) and the fact that trajectories passed through the region of ice saturation in one day imply selective growth of a small fraction of particles to sizes large enough (>10 micrometers) to be irreversibly removed on this timescale. Over 25% of the Arctic vortex in a 20-30 K range Transport of theta is estimated to have been dehydrated in this event.

  2. Energy efficient recovery and dehydration of ethanol from fermentation broths by Membrane Assisted Vapor Stripping technology

    EPA Science Inventory

    Distillation combined with molecular sieve dehydration is the current state of the art for fuel grade ethanol production from fermentation broths. To improve the sustainability of bioethanol production, energy efficient separation alternatives are needed, particularly for lower ...

  3. Membrane-based recovery and dehydration of alcohols from fermentation broths - of materials and modules

    EPA Science Inventory

    Distillation combined with molecular sieve dehydration is the current state of the art for fuel grade ethanol production from fermentation broths. As the liquid biofuels industry transitions to lignocellulosic feedstocks, expands the end product portfolio to include other alcoho...

  4. Energy Efficient Hybrid Vapor Stripping-Vapor Permeation Process for Ethanol Recovery ad Dehydration

    EPA Science Inventory

    Distillation combined with molecular sieve dehydration is the current state of the art for fuel grade ethanol production from fermentation broths. To improve the sustainability of bioethanol production, energy efficient separation alternatives are needed, particularly for lower f...

  5. Coseismic dehydration from illite-rich faults and its implications on the slip-weakening, frictional heating, and earthquake enegetics

    NASA Astrophysics Data System (ADS)

    Hirono, T.; Tanikawa, W.

    2010-12-01

    Transient frictional heating during earthquake slip induces dehydroxylation of phyllosilicate minerals. As this reaction is endothermic and releases H2O, it may affect dynamic fault weakening and energetics during earthquakes. To elucidate this question, we tested illite-dominant shale as one of the representative components in the crustal active faults and subduction-boundary faults. We first measured the specific heat capacity and thermal diffusivity along with the temperature dependencies of these parameters, and determined weight loss and enthalpy of the dehydroxylation reaction to be 5.22 wt% and 0.2895 kJ g-1, respectively. We applied the Friedman analysis for the weight loss data of four heating experiments of 5, 10, 15 and 20 °C min-1, and found that the dehydroxylation was well fitted as two steps reaction of n-dimensional nucleation mechanism according to Avrami-Erofeev with n=0.5 (first step) and two-dimensional diffusion (second step). On the basis of these experimental results, we performed numerical analyses of dynamic fault weakening, taking into account the dehydroxylation reaction of illite. We clarify that released fluids assist in the pressurization of pore fluid and subsequently induce a decrease in effective normal stress on faults, and that the dehydroxylation reaction takes up heat from the energy released on the fault during earthquake slip. This effect, which inhibits the rise in temperature in the fault, is significant at depths of >2 km, and fraction of energy used for the reaction against the total given work on the fault reaches 18% at the depths. Thus, the coseismic dehydration from phyllosilicate minerals may significantly affect on the slip-weakening, frictional heating, and energetics in clay-rich faults such as crustal active faults and subduction boundary faults.

  6. Simple Simulations of DNA Condensation

    SciTech Connect

    STEVENS,MARK J.

    2000-07-12

    Molecular dynamics simulations of a simple, bead-spring model of semiflexible polyelectrolytes such as DNA are performed. All charges are explicitly treated. Starting from extended, noncondensed conformations, condensed structures form in the simulations with tetravalent or trivalent counterions. No condensates form or are stable for divalent counterions. The mechanism by which condensates form is described. Briefly, condensation occurs because electrostatic interactions dominate entropy, and the favored Coulombic structure is a charge ordered state. Condensation is a generic phenomena and occurs for a variety of polyelectrolyte parameters. Toroids and rods are the condensate structures. Toroids form preferentially when the molecular stiffness is sufficiently strong.

  7. Microwave heat treatment of apple before air dehydration – effects on physical properties and microstructure

    Microsoft Academic Search

    Tomas Funebo; L??l??a Ahrné; Siw Kidman; Maud Langton; Christina Skjöldebrand

    2000-01-01

    Golden delicious apple cubes were heated with microwave energy of high intensity (20 W\\/g), as a pre-treatment before air-dehydration at 40°C, 60°C and 80°C. After the microwave treatment extending for 0.75 up to 5 min, the cubes were finish-dried with only forced air at 2 m\\/s. Dehydrated and rehydrated samples were analysed with a puncture test using a texture analyser.

  8. A rapid and inexpensive method for isolation of total DNA from dehydrated plant tissue

    Microsoft Academic Search

    Thomas H. Tai; Steven D. Tanksley

    1990-01-01

    We describe an inexpensive method for dehydration of plant tissue and extraction of high molecular weight DNA. Tissue is dried\\u000a for 12 to 24 hours in a food dehydrator and subsequently powdered for DNA extraction. Dicot tissue can be powdered in centrifuge\\u000a tubesen masse using a commercial paint mixer and glass beads. With the use of the paint mixer, tissue

  9. Dehydration in the Arctic stratosphere during the SOLVE\\/THESEO-2000 campaigns

    Microsoft Academic Search

    C. Schiller; R. Bauer; T. Deshler; A. Dörnbrack; J. Elkins; A. Engel; H. Flentje; N. Larsen; I. Levin; M. Müller; S. Oltmans; H. Ovarlez; J. Ovarlez; J. Schreiner; F. Stroh; C. Voigt; H. Vömel

    2002-01-01

    Balloon-borne measurements of H2O, CH4, and H2 in January and March 2000 show clear evidence for dehydration inside the polar vortex. At 30-50 hPa, total hydrogen is reduced by approximately 0.5 ppmv. This phenomenon is apparent in all five in situ balloon observations of this period; therefore it is probable that dehydration occurred over extended regions and a long period

  10. Drying of Chestnuts (Castanea sativa Mill.) after Osmotic Dehydration with Sucrose and Glucose Solutions

    Microsoft Academic Search

    R. Moreira; F. Chenlo; L. Chaguri; H. Oliveira

    2007-01-01

    Chestnuts were dehydrated by using a combined method of osmotic dehydration followed by air drying. Samples were osmotically pretreated with sucrose (60% w\\/w) and glucose (56% w\\/w) for 8 h, air-dried at temperatures of 45, 55, and 65°C, at a relative humidity of 30% and at a velocity of 2.7 m·s and the experimental data of the drying kinetics were obtained. Whole samples were

  11. Air drying and colour characteristics of chestnuts pre-submitted to osmotic dehydration with sodium chloride

    Microsoft Academic Search

    R. Moreira; F. Chenlo; L. Chaguri; G. Vázquez

    2011-01-01

    Air drying kinetics of chestnuts (Castanea sativa Mill.) submitted previously to osmotic dehydration with sodium chloride solutions (22%, w\\/w, 25°C, 8h) were experimentally determined. Drying experiments were carried out at 45, 55 and 65°C during 32h. Before osmotic dehydration operation, shell and tegument tissue were carefully removed in all samples. Rough external surface was maintained (peeled samples) or also removed

  12. Mass transfer during osmotic dehydration of pineapple: considering Fickian diffusion in cubical configuration

    Microsoft Academic Search

    N. K Rastogi; K. S. M. S Raghavarao

    2004-01-01

    Osmotic dehydration kinetics of pineapple cubes (15×15×15mm3) was studied over a range of concentration (40–70°B) and temperature (30–50°C) of osmotic solution. The effective diffusion coefficients for water and solute diffusion were determined, considering pineapple as cubical configuration, assuming osmotic dehydration to be governed by Fickian diffusion. The effective diffusion coefficients for water as well as solute were empirically correlated with

  13. Pelletisation of canola meal by extrusion-spheronisation for ethanol dehydration

    E-print Network

    Niu, C.H.; Baylak, T.; Wilson, D.I.; Zhang, M.

    2014-07-02

    places pressure on food supply. Alternative bioadsorbents for bioethanol dehydration included cellulosic materials such as canola meal [3], kenaf core [4], and bleached wood pulp [4], and starchy materials such as cassava pearls [5] and corn meal [6... CE. Cellulose based adsorbent materials for the dehydration of ethanol using thermal swing adsorption. Adsorpt. J. Int. Adsorpt. Soc. 2005; 11: 697-701. [5] Kim Y, Hendrickson R, Mosier N, Hilaly A, Ladisch MR. Cassava starch pearls as a desiccant...

  14. The dehydration and rehydration characteristics of the seeded breadfruit or breadnut seed

    Microsoft Academic Search

    L. Harrynanan; C. K. Sankat

    2008-01-01

    Harrynanan, L. and Sankat, C. K. 2008. The dehydration and rehydration characteristics of the seeded breadfruit or breadnut seed. Canadian Biosystems Engineering\\/Le genie des biosystems auCanada 50: 3.373.45. Experiments were carried out to determine the effects of dehydration and rehydration of in-shell mature breadnut seeds. Pretreated (cooked in salted water) and untreated in-shell mature breadnut seeds were dried in a

  15. Phenolic Profile and Antioxidant Capacity of Chickpeas ( Cicer arietinum L.) as Affected by a Dehydration Process

    Microsoft Academic Search

    Yolanda Aguilera; Montserrat Dueñas; Isabel Estrella; Teresa Hernández; Vanesa Benitez; Rosa María Esteban; María A. Martín-Cabrejas

    This study presents the effects of soaking, cooking and industrial dehydration on the phenolic profile, and antioxidant capacity\\u000a in two chickpea varieties (Sinaloa and Castellano). Chromatographic analysis identified a total of 24 phenolic components,\\u000a being isoflavones the main phenolics in raw and processed Sinaloa and Castellano flours. The impact of the industrial dehydration\\u000a was different depending on the chickpea variety.

  16. Kinetics of the dehydration of alcohols in presence of tricalcium phosphate

    Microsoft Academic Search

    L. Kh. Freydlin; A. M. Levit

    1952-01-01

    Summary An investigation has been made into the kinetics of the dehydration in presence of tricalcium phosphate as catalyst of ethyl, n-propyl, isopropyl, n-butyl, and isobutyl alcohols.1.It has been established that in presence of tricalcium phosphate the dehydration of alcohols proceeds in a very selective fashion, the content of unsaturated compounds in the gas being 98–99%.2.It has been found that

  17. Vat dye sorption onto crude dehydrated sewage sludge.

    PubMed

    Dhaouadi, H; M'henni, F

    2009-05-30

    In this work, sewage sludge is used as a textile dye adsorbent. A sample of crude dehydrated sewage sludge issued from an urban wastewater treatment plant (high-rate aeration, activated sludge process, Sahline, Tunisia) is utilized for vat dye retention. The main objective of this work is to evaluate the "efficiency" of the crude material on vat dye sorption. However, no treatment to modify any of the adsorbent properties was considered. Although the relatively low specific surface area (about 3.2m(2)g(-1)) compared to more conventional adsorbents, the used material shows very interesting retention capacities when used with water pollutants. The pseudo, first and second order kinetic models have been used to investigate the retention mechanism. When linearized, the pseudo-second order fit, for the both used dyes, in a better way the obtained experimental results than the pseudo-first order kinetic model. For equilibrium dye uptake amount it is found that the used material has a capacity (Langmuir Freundlich monolayer) of 73.1mg/g to fix the VAT RED 10 and 58.7 mg/g to fix the VAT ORANGE 11. PMID:18809247

  18. Possible contributions of pileus clouds to TTL dehydration

    NASA Astrophysics Data System (ADS)

    Garrett, T. J.

    2004-12-01

    Measurements from CRYSTAL-FACE show that thin tropopause cirrus (TTC) was frequently present above anvil cirrus. TTC was typically a hundred times more tenuous, about 20 K colder, and had similar horizontal dimensions to the anvil. Photography, as well as analysis of the cloud dynamics, chemistry, and isotopic ratios has led to a hypothesis that the tropopause cirrus formed initially as cap-shaped pileus clouds over deep convective turrets. The pileus spread as stratiform layers over the anvil, where they were shielded from heating from terrestrial infrared radiation. Here we propose possible implications of pileus cloud formation to the process of stratospheric dehydration. In the moist stratified tropopause transition layer (TTL), isentropes are bent upwards ahead of deep convection. A thin pileus cloud may form if isentropic surfaces are raised sufficiently that air is cooled to the point of homogeneous ice nucleation. If the TTL was initially supersaturated with respect to ice (as is often observed), once the convection subsides and the isentropes flatten, a stratiform TTC cloud lingers. As the anvil beneath the TTC thins, the TTC is increasingly exposed to radiative heating from the earth's surface, and it is lofted upwards. If it precipitates it may contribute to the dessication of the lower stratosphere.

  19. Freeze avoidance: a dehydrating moss gathers no ice.

    PubMed

    Lenné, Thomas; Bryant, Gary; Hocart, Charles H; Huang, Cheng X; Ball, Marilyn C

    2010-10-01

    Using cryo-SEM with EDX fundamental structural and mechanical properties of the moss Ceratodon purpureus (Hedw.) Brid. were studied in relation to tolerance of freezing temperatures. In contrast to more complex plants, no ice accumulated within the moss during the freezing event. External ice induced desiccation with the response being a function of cell type; water-filled hydroid cells cavitated and were embolized at -4 °C while parenchyma cells of the inner cortex exhibited cytorrhysis, decreasing to ? 20% of their original volume at a nadir temperature of -20 °C. Chlorophyll fluorescence showed that these winter acclimated mosses displayed no evidence of damage after thawing from -20 °C while GCMS showed that sugar concentrations were not sufficient to confer this level of freezing tolerance. In addition, differential scanning calorimetry showed internal ice nucleation occurred in hydrated moss at ?-12 °C while desiccated moss showed no evidence of freezing with lowering of nadir temperature to -20 °C. Therefore the rapid dehydration of the moss provides an elegantly simple solution to the problem of freezing; remove that which freezes. PMID:20525002

  20. Dehydrating and Sterilizing Wastes Using Supercritical CO2

    NASA Technical Reports Server (NTRS)

    Brown, Ian J.

    2006-01-01

    A relatively low-temperature process for dehydrating and sterilizing biohazardous wastes in an enclosed life-support system exploits (1) the superior mass-transport properties of supercritical fluids in general and (2) the demonstrated sterilizing property of supercritical CO2 in particular. The wastes to be treated are placed in a chamber. Liquid CO2, drawn from storage at a pressure of 850 psi (approx.=5.9 MPa) and temperature of 0 C, is compressed to pressure of 2 kpsi (approx.=14 MPa) and made to flow into the chamber. The compression raises the temperature to 10 C. The chamber and its contents are then further heated to 40 C, putting the CO2 into a supercritical state, in which it kills microorganisms in the chamber. Carrying dissolved water, the CO2 leaves the chamber through a back-pressure regulator, through which it is expanded back to the storage pressure. The expanded CO2 is refrigerated to extract the dissolved water as ice, and is then returned to the storage tank at 0 C

  1. Mild dehydrated hereditary stomatocytosis revealed by marked hepatosiderosis.

    PubMed

    Syfuss, P-Y; Ciupea, A; Brahimi, S; Cynober, T; Stewart, G W; Grandchamp, B; Beaumont, C; Tchernia, G; Delaunay, J; Wagner, J-C

    2006-08-01

    We report a patient in whom hepatosiderosis was diagnosed at the age of 55 years and who has since been treated by regular bleeding. The H63D mutation was found in the heterozygous state in the HFE gene. No mutation was recorded in the SLC11A3 gene (ferroportin). Hepatosiderosis did not seem primary, nevertheless its cause long remained elusive. Only 2 years ago did we find the responsible condition, a very mildly expressed form of dehydrated hereditary stomatocytosis (DHS). This genetic disease is a strongly iron-loading condition. Haemolysis was fully compensated. Kalaemia was slightly elevated, suggesting a pseudohyperkalaemia that may be associated with DHS. Osmotic gradient ektacytometry allowed to assess the diagnosis of DHS. The red cell monovalent Na+ and K+ concentrations were moderately elevated and reduced respectively. The temperature dependence of the ouabain + bumetanide-resistant K+ influx produced a shallow slope, above and parallel to the control curve. These features were consistent with the diagnosis of DHS. The pronounced hepatosiderosis contrasted with the mildly expressed DHS, and with the ferritinaemia that was slightly elevated, if at all, prior to bleeding. Bleeding caused ferritinaemia to decrease and hepatosiderosis to recede. The whole picture accounts for a misleading presentation of DHS, in which the primary condition long remained hidden behind one of its remotest complications, hepatosiderosis. PMID:16898969

  2. Detail of Bright Angel stone vault, containing condenser, Hoffman condensation ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail of Bright Angel stone vault, containing condenser, Hoffman condensation pump, Jennings vacuum heating pump, and misc. pipes and valves. - Grand Canyon Village Utilities, Grand Canyon National Park, Grand Canyon Village, Coconino County, AZ

  3. Evaporation, Condensation, and Precipitation

    NSDL National Science Digital Library

    Miss Brown

    2009-10-21

    After completion of this project students should have an understanding of evaporation, condensation, and precipitation in the water cycle. Use the websites provided to answer the questions. Record your answers on the spreadsheet provided. Do you understand how the water cycle works? Begin by watching this short video about the water cycle.water cycle video Use the website to define condensation, precipitation, and evaporation?water cycle List the different types of precipitation from the site.types of precipitation Follow the directions to the experiment on this website to get a better understanding of how evaporation takes ...

  4. Repeated bouts of dehydration deplete nutrient reserves and reduce egg production in the mosquito Culex pipiens

    PubMed Central

    Benoit, Joshua B.; Patrick, Kevin R.; Desai, Karina; Hardesty, Jeffrey J.; Krause, Tyler B.; Denlinger, David L.

    2010-01-01

    In this study of the mosquito, Culex pipiens, we examined the impact of multiple bouts of dehydration and rehydration on survival, depletion of metabolic reserves and egg production in both non-diapausing and diapausing females. Mosquitoes provided with access to sugar during rehydration survived longer than those allowed to rehydrate without sugar, and their survival was similar to that of mosquitoes of the same age that were not dehydrated. Among mosquitoes not provided with sugar, each dehydration bout reduced the mosquito's dry mass – an effect likely to be due to the utilization of carbohydrates and lipid reserves. The toll on glycogen and lipid reserves is likely to be especially costly for diapausing mosquitoes that are dependent on these stored reserves for winter survival. Egg production in both non-diapausing and post-diapausing C. pipiens was also reduced in response to multiple bouts of dehydration. Although egg quality was not compromised, the number of eggs produced was reduced. Both non-diapausing and diapausing females can compensate for the nutrient loss due to dehydration by sugar feeding but the opportunity to feed on sugar is likely to be rarely available in the overwintering habitat of diapausing females, thus the impact of dehydration may be especially pronounced in overwintering populations of C. pipiens. PMID:20675546

  5. Gene expression changes governing extreme dehydration tolerance in an Antarctic insect

    PubMed Central

    Teets, Nicholas M.; Peyton, Justin T.; Colinet, Herve; Renault, David; Kelley, Joanna L.; Kawarasaki, Yuta; Lee, Richard E.; Denlinger, David L.

    2012-01-01

    Among terrestrial organisms, arthropods are especially susceptible to dehydration, given their small body size and high surface area to volume ratio. This challenge is particularly acute for polar arthropods that face near-constant desiccating conditions, as water is frozen and thus unavailable for much of the year. The molecular mechanisms that govern extreme dehydration tolerance in insects remain largely undefined. In this study, we used RNA sequencing to quantify transcriptional mechanisms of extreme dehydration tolerance in the Antarctic midge, Belgica antarctica, the world’s southernmost insect and only insect endemic to Antarctica. Larvae of B. antarctica are remarkably tolerant of dehydration, surviving losses up to 70% of their body water. Gene expression changes in response to dehydration indicated up-regulation of cellular recycling pathways including the ubiquitin-mediated proteasome and autophagy, with concurrent down-regulation of genes involved in general metabolism and ATP production. Metabolomics results revealed shifts in metabolite pools that correlated closely with changes in gene expression, indicating that coordinated changes in gene expression and metabolism are a critical component of the dehydration response. Finally, using comparative genomics, we compared our gene expression results with a transcriptomic dataset for the Arctic collembolan, Megaphorura arctica. Although B. antarctica and M. arctica are adapted to similar environments, our analysis indicated very little overlap in expression profiles between these two arthropods. Whereas several orthologous genes showed similar expression patterns, transcriptional changes were largely species specific, indicating these polar arthropods have developed distinct transcriptional mechanisms to cope with similar desiccating conditions. PMID:23197828

  6. Na(x)-deficient mice show normal vasopressin response to dehydration.

    PubMed

    Nagakura, Ayano; Hiyama, Takeshi Y; Noda, Masaharu

    2010-03-26

    In dehydrated animals, the antidiuretic hormone vasopressin (VP) is released from the nerve terminals of magnocellular neurons of the supraoptic nucleus (SON) and paraventricular nucleus (PVN) into the systemic circulation at the posterior pituitary. Increases in sodium (Na+)-level and osmolality in body fluids upon dehydration are reportedly sensed by a Na+-sensor and/or an osmosensor, respectively. However, it is still unknown whether both are involved in the regulation of production and/or release of VP. Na(x) is the cerebral Na+-level sensor and Na(x)-knockout mice do not stop ingesting salt even when dehydrated. Here we examined VP production/release in Na(x)-knockout mice, and found that they are normal in the VP response to dehydration or intraperitoneal-administration with hypertonic saline. In situ hybridization using an intron-specific probe showed that VP gene expression in the SON did not differ from wild-type mice when dehydrated. Also, there was no significant difference in the activity of subfornical organ neurons projecting to the SON between the two genotypes when stimulated by water deprivation. Furthermore, Na(x)-knockout mice showed a normal response in urine excretion to dehydration. All these results indicate that the information of Na+-level increase detected by Na(x) does not contribute to the control of VP production/release. PMID:20138121

  7. Proteome analysis of Physcomitrella patens exposed to progressive dehydration and rehydration

    PubMed Central

    Cui, Suxia; Hu, Jia; Guo, Shilei; Wang, Jie; Cheng, Yali; Dang, Xinxing; Wu, Lili; He, Yikun

    2012-01-01

    Physcomitrella patens is an extremely dehydration-tolerant moss. However, the molecular basis of its responses to loss of cellular water remains unclear. A comprehensive proteomic analysis of dehydration- and rehydration-responsive proteins has been conducted using quantitative two-dimensional difference in-gel electrophoresis (2D-DIGE), and traditional 2-D gel electrophoresis (2-DE) combined with MALDI TOF/TOF MS. Of the 216 differentially-expressed protein spots, 112 and 104 were dehydration- and rehydration-responsive proteins, respectively. The functional categories of the most differentially-expressed proteins were seed maturation, defence, protein synthesis and quality control, and energy production. Strikingly, most of the late embryogenesis abundant (LEA) proteins were expressed at a basal level under control conditions and their synthesis was strongly enhanced by dehydration, a pattern that was confirmed by RT-PCR. Actinoporins, phosphatidylethanolamine-binding protein, arabinogalactan protein, and phospholipase are the likely dominant players in the defence system. In addition, 24 proteins of unknown function were identified as novel dehydration- or rehydration-responsive proteins. Our data indicate that Physcomitrella adopts a rapid protein response mechanism to cope with dehydration in its leafy-shoot and basal expression levels of desiccation-tolerant proteins are rapidly upgraded at high levels under stress. This mechanism appears similar to that seen in angiosperm seeds. PMID:21994173

  8. Strategies in Optimizing Condensate Return

    E-print Network

    Bloom, D.

    Optimizing condensate return for reuse as boiler feedwater is often a viable means of reducing fuel costs and improving boiler system efficiency. As more condensate is returned, less makeup is required and savings on water and water treatment costs...

  9. Influence of the nature of the R group on the hydrolysis and condensation process of trifunctional silicon alkoxides, R-Si(OR{prime}){sub 3}

    SciTech Connect

    Delattre, L.; Babonneau, F. [Univ. Pierre et Marie Curie, Paris (France). Chimie de la Matiere Condensee

    1994-12-31

    The hydrolysis and condensation reactions of three trifunctional silicon alkoxides, R-Si(OEt){sub 3}, with various R alkyl chains (R = CH{sub 3}, C{sub 2}H{sub 5}, C{sub 8}H{sub 17}), was followed by {sup 29}Si and {sup 1}H Nuclear Magnetic Resonance. The condensation reactions are faster for methyltriethoxysilane and the degree of condensation of the system is higher. The other two systems have similar behaviors during the first hours, with lowest degree of condensation. The condensation reactions slow down for the octyltriethoxysilane, due to the presence of the long alkyl chains which prevent condensation reactions between oligomeric species. The influence of the addition of tetraethoxysilane (TEOS) was studied: for all three systems, the degree of condensation of the network is higher, indicating the role of cross-linking played by TEOS.

  10. MUNICIPAL LANDFILL GAS CONDENSATE

    EPA Science Inventory

    New regulations relative to air emissions from municipal landfills may require the installation of gas collection systems at landfills. As landfill gas (LFG) is collected, water and other vapors in the gas condense in the system or are purposely removed in the normal treatment of...

  11. Cloud Condensation Nuclei Sizes

    Microsoft Academic Search

    J. G. Hudson; S. Mishra

    2006-01-01

    The sizes of cloud condensation nuclei (CCN) can be determined by first passing an aerosol sample through a differential mobility analyzer (DMA) and then to a CCN counter or spectrometer (i.e., Hudson 1989), which provides a mean value of the critical supersaturation (Sc) of the particles. By sequentially dialing in several different DMA sizes a relationship between dry particle size

  12. Steam and Condensate Systems 

    E-print Network

    Yates, W.

    1979-01-01

    STEAM AND CONDENSATE SYSTEM Wesley Yates Yarway Corporation Houston, Texas In the late 60's and early 70's oil was plentiful and steam was relatively inexpen sive. The switch to low sulphur fuel oil and the oil embargo suddenly changed the pic...

  13. Asymmetric condensed dark matter

    E-print Network

    Anthony Aguirre; Alberto Diez-Tejedor

    2015-02-25

    We explore the viability of a boson dark matter candidate with an asymmetry between the number densities of particles and antiparticles. A simple thermal field theory analysis confirms that, under certain general conditions, this component would develop a Bose-Einstein condensate in the early universe that, for appropriate model parameters, could survive the ensuing cosmological evolution until now. The condensation of a dark matter component in equilibrium with the thermal plasma is a relativistic process, hence the amount of matter dictated by the charge asymmetry is complemented by a hot relic density frozen out at the time of decoupling. Contrary to the case of ordinary WIMPs, dark matter particles in a condensate can be very light, $10^{-22}\\,{\\rm eV} \\lesssim m \\lesssim 10^2\\,{\\rm eV}$; the lower limit arises from constraints on small-scale structure formation, while the upper bound ensures that the density from thermal relics is not too large. Big-Bang nucleosynthesis constrains the temperature of decoupling to the scale of the QCD phase transition or above. This requires large dark matter-to-photon ratios and very weak interactions with standard model particles. Finally, we argue that a given boson particle that was in thermal equilibrium in the early universe may be in a condensate, or in the form of thermal relics, but we cannot have a combination of both contributing significantly to the mass density today.

  14. Re-Condensation

    E-print Network

    Bhatia, P.; Kozman, T.

    2004-01-01

    When steam transfers its heat in a manufacturing process or heat exchanger, it may revert to a liquid phase called condensate. This paper presents a method to help certain manufacturing and petro-chemical companies to save energy costs by returning their...

  15. Re-Condensation 

    E-print Network

    Bhatia, P.; Kozman, T.

    2004-01-01

    When steam transfers its heat in a manufacturing process or heat exchanger, it may revert to a liquid phase called condensate. This paper presents a method to help certain manufacturing and petro-chemical companies to save energy costs by returning their...

  16. Soft condensed matter physics

    Microsoft Academic Search

    T. C. Lubensky

    1997-01-01

    Soft condensed matter physics is the study of materials, such as fluids, liquid crystals, polymers, colloids and emulsions, that are “soft” to the touch. This article will review some properties, such as the dominance of entropy, that are unique to soft materials and some properties such as the interplay between broken-symmetry, dynamic mode structure and topological defects that are common

  17. Condensed-Matter Physics.

    ERIC Educational Resources Information Center

    Hirsch, Jorge E.; Scalapino, Douglas J.

    1983-01-01

    Discusses ways computers are being used in condensed-matter physics by experimenters and theorists. Experimenters use them to control experiments and to gather and analyze data. Theorists use them for detailed predictions based on realistic models and for studies on systems not realizable in practice. (JN)

  18. Condensed matter physics journals

    Microsoft Academic Search

    R. Todorov

    1983-01-01

    On the basis of a citation\\/reference criterion, 20 core journals are selected in the field of condensed matter physics. Citation data and indicators from 1980Journal Citation Reports reveal their different characteristic features such as applied orientation, communication function and longevity. The manually obtained data for the core journals are written into a matrix in order to determine an appropriate ranking

  19. Condensed Matter Physics

    Microsoft Academic Search

    I Strzalkowski

    2000-01-01

    Condensed matter physics constitutes nowadays an enormous field of knowledge. To write a good textbook covering all main topics in that field in a suitable way and in a reasonable volume is very hard indeed. I believe Michael Marder has achieved this goal with great success. The text is arranged in six parts. Part I describes the atomic structure of

  20. DEPARTMENT OF CONDENSED MATTER PHYSICS

    E-print Network

    Shyamasundar, R.K.

    DEPARTMENT OF CONDENSED MATTER PHYSICS AND MATERIALS SCIENCE Welcome to the Department of Condensed Matter Physics and Materials Science (CMPMS) at TIFR! Research in CMPMS asks questions about j a y a r a g h a v a n #12;Condensed Matter Physics & Materials Science Research areas A common

  1. Physics 232 Condensed Matter Physics

    E-print Network

    Young, A. Peter

    1 Physics 232 Condensed Matter Physics Instructor: Peter Young Office: 212 ISB Telephone: 459://apyoung.com/232 TOPICS This course on condensed matter physics will cover three areas: · magnetism, · optical physics such as Condensed Matter Physics by M. Mardar Solid State Physics by N. Ashroft and N. D. Mermin

  2. Dehydration melting of nominally anhydrous mantle: The primacy of partitioning

    NASA Astrophysics Data System (ADS)

    Hirschmann, Marc M.; Tenner, Travis; Aubaud, Cyril; Withers, A. C.

    2009-09-01

    The onset of dehydration melting of nominally anhydrous peridotite can be calculated by combination of appropriate mineral/melt partition coefficients for H 2O, DHmin/liq, and a parameterization of the influence of the H 2O content of melt on the solidus of peridotite. Thermodynamic models predict that olivine/melt partitioning, DHol/liq, should increase with pressure, and though direct experimental determinations of DHol/liq from 0.5 to 3 GPa do not show the predicted pressure dependence, storage capacity experiments suggest increases in DHol/liq at pressures above 8 GPa and particularly at 12-14 GPa, near the base of the upper mantle. Calculations using experimental values of DHmin/liq and ignoring the likely effect of pressure on DHol/liq indicate that DHperid/liq increases from 0.006 at 1 GPa up to 0.009 at the onset of garnet stability at 2.8 GPa and then diminishes with further increases in pressure owing to decreasing pyroxene mode and decreasing Al in pyroxene. Because these calculations ignore the likely pressure effect on DHol/liq, they represent minima. Incipient partial melts of mantle with 100 ppm H 2O have 1-2 wt.% H 2O from 1 to 5 GPa, and this modest H 2O concentration limits the stability of hydrous partial melts to temperatures approaching the dry solidus. The influence of H 2O on the melting behavior of peridotite can be quantified using a simple cryoscopic approach benchmarked against experiments on hydrous peridotite. Along a mantle adiabat with a potential temperature of 1323 °C, calculations indicate that dehydration partial melting of peridotite with 100 ppm H 2O begins at 80 km, or about 15 km deeper than would be the case for truly dry peridotite. However, decreases in DHperid/liq related to the onset of the stability of garnet mean that mantle modestly enriched in H 2O will begin melting significantly deeper, i.e., at 104 km for 200 ppm H 2O. In the low velocity zone (LVZ) beneath mature (50 Ma) oceanic lithosphere, incipient partial melting at 110 km requires 300 ppm H 2O and generation of small finite (?0.1%) melt fractions across the entire LVZ from 90 to 200 km requires 600 ppm H 2O. The minimum concentration, 300 ppm H 2O, is 2-3 times that of typical convecting oceanic (MORB-source) mantle, so it is not likely that pervasive hydrous partial melting is responsible for the seismic properties of the LVZ. Extrapolation of low pressure partition coefficients to the base of the upper mantle indicates that at least 500 ppm H 2O is required to induce partial melting at depths of 300-400 km along a normal mantle geotherm. This argues that typical upper mantle with ˜100 ppm H 2O is not produced by partial melting above the 410 km discontinuity. Furthermore, the 500 ppm H 2O concentration is likely to be an underestimate, as it does not take into account probable enhancement in DHmin/liq at high pressure.

  3. Evaporation and condensation at a liquid surface. I. Argon

    NASA Astrophysics Data System (ADS)

    Yasuoka, Kenji; Matsumoto, Mitsuhiro; Kataoka, Yosuke

    1994-11-01

    Molecular dynamics computer simulations were carried out to investigate the dynamics of evaporation and condensation for argon at the temperature of 80 and 100 K. From the decrease of the survival probability of vapor molecules, the ratio of self reflection to collision is estimated to be 12%-15%, only weakly dependent on the temperature. This suggests that argon vapor molecules are in the condition of almost complete capture, and the condensation is considered to be a barrierless process. The total ratio of reflection which is evaluated with the flux correlation of condensation and evaporation is 20% at both temperature. The difference between these two ratios of reflection is ascribed to a phenomenon that vapor molecules colliding with the surface drive out other liquid molecules. This molecule exchange at the surface is as important as the self-reflection, and the conventional picture of condensation as a unimolecular chemical reaction is not appropriate.

  4. Selective brain cooling reduces water turnover in dehydrated sheep.

    PubMed

    Strauss, W Maartin; Hetem, Robyn S; Mitchell, Duncan; Maloney, Shane K; Meyer, Leith C R; Fuller, Andrea

    2015-01-01

    In artiodactyls, arterial blood destined for the brain can be cooled through counter-current heat exchange within the cavernous sinus via a process called selective brain cooling. We test the hypothesis that selective brain cooling, which results in lowered hypothalamic temperature, contributes to water conservation in sheep. Nine Dorper sheep, instrumented to provide measurements of carotid blood and brain temperature, were dosed with deuterium oxide (D2O), exposed to heat for 8 days (40 ?C for 6-h per day) and deprived of water for the last five days (days 3 to 8). Plasma osmolality increased and the body water fraction decreased over the five days of water deprivation, with the sheep losing 16.7% of their body mass. Following water deprivation, both the mean 24h carotid blood temperature and the mean 24h brain temperature increased, but carotid blood temperature increased more than did brain temperature resulting in increased selective brain cooling. There was considerable inter-individual variation in the degree to which individual sheep used selective brain cooling. In general, sheep spent more time using selective brain cooling, and it was of greater magnitude, when dehydrated compared to when they were euhydrated. We found a significant positive correlation between selective brain cooling magnitude and osmolality (an index of hydration state). Both the magnitude of selective brain cooling and the proportion of time that sheep spent selective brain cooling were negatively correlated with water turnover. Sheep that used selective brain cooling more frequently, and with greater magnitude, lost less water than did conspecifics using selective brain cooling less efficiently. Our results show that a 50 kg sheep can save 2.6L of water per day (~60% of daily water intake) when it employs selective brain cooling for 50% of the day during heat exposure. We conclude that selective brain cooling has a water conservation function in artiodactyls. PMID:25675092

  5. Selective Brain Cooling Reduces Water Turnover in Dehydrated Sheep

    PubMed Central

    Strauss, W. Maartin; Hetem, Robyn S.; Mitchell, Duncan; Maloney, Shane K.; Meyer, Leith C. R.; Fuller, Andrea

    2015-01-01

    In artiodactyls, arterial blood destined for the brain can be cooled through counter-current heat exchange within the cavernous sinus via a process called selective brain cooling. We test the hypothesis that selective brain cooling, which results in lowered hypothalamic temperature, contributes to water conservation in sheep. Nine Dorper sheep, instrumented to provide measurements of carotid blood and brain temperature, were dosed with deuterium oxide (D2O), exposed to heat for 8 days (40?C for 6-h per day) and deprived of water for the last five days (days 3 to 8). Plasma osmolality increased and the body water fraction decreased over the five days of water deprivation, with the sheep losing 16.7% of their body mass. Following water deprivation, both the mean 24h carotid blood temperature and the mean 24h brain temperature increased, but carotid blood temperature increased more than did brain temperature resulting in increased selective brain cooling. There was considerable inter-individual variation in the degree to which individual sheep used selective brain cooling. In general, sheep spent more time using selective brain cooling, and it was of greater magnitude, when dehydrated compared to when they were euhydrated. We found a significant positive correlation between selective brain cooling magnitude and osmolality (an index of hydration state). Both the magnitude of selective brain cooling and the proportion of time that sheep spent selective brain cooling were negatively correlated with water turnover. Sheep that used selective brain cooling more frequently, and with greater magnitude, lost less water than did conspecifics using selective brain cooling less efficiently. Our results show that a 50kg sheep can save 2.6L of water per day (~60% of daily water intake) when it employs selective brain cooling for 50% of the day during heat exposure. We conclude that selective brain cooling has a water conservation function in artiodactyls. PMID:25675092

  6. Early Transcriptional Response of Soybean Contrasting Accessions to Root Dehydration

    PubMed Central

    Ferreira Neto, José Ribamar Costa; Pandolfi, Valesca; Guimaraes, Francismar Corrêa Marcelino; Benko-Iseppon, Ana Maria; Romero, Cynara; Silva, Roberta Lane de Oliveira; Rodrigues, Fabiana Aparecida; Abdelnoor, Ricardo Vilela; Nepomuceno, Alexandre Lima; Kido, Ederson Akio

    2013-01-01

    Drought is a significant constraint to yield increase in soybean. The early perception of water deprivation is critical for recruitment of genes that promote plant tolerance. DeepSuperSAGE libraries, including one control and a bulk of six stress times imposed (from 25 to 150 min of root dehydration) for drought-tolerant and sensitive soybean accessions, allowed to identify new molecular targets for drought tolerance. The survey uncovered 120,770 unique transcripts expressed by the contrasting accessions. Of these, 57,610 aligned with known cDNA sequences, allowing the annotation of 32,373 unitags. A total of 1,127 unitags were up-regulated only in the tolerant accession, whereas 1,557 were up-regulated in both as compared to their controls. An expression profile concerning the most representative Gene Ontology (GO) categories for the tolerant accession revealed the expression “protein binding” as the most represented for “Molecular Function”, whereas CDPK and CBL were the most up-regulated protein families in this category. Furthermore, particular genes expressed different isoforms according to the accession, showing the potential to operate in the distinction of physiological behaviors. Besides, heat maps comprising GO categories related to abiotic stress response and the unitags regulation observed in the expression contrasts covering tolerant and sensitive accessions, revealed the unitags potential for plant breeding. Candidate genes related to “hormone response” (LOX, ERF1b, XET), “water response” (PUB, BMY), “salt stress response” (WRKY, MYB) and “oxidative stress response” (PER) figured among the most promising molecular targets. Additionally, nine transcripts (HMGR, XET, WRKY20, RAP2-4, EREBP, NAC3, PER, GPX5 and BMY) validated by RT-qPCR (four different time points) confirmed their differential expression and pointed that already after 25 minutes a transcriptional reorganization started in response to the new condition, with important differences between both accessions. PMID:24349513

  7. Framework for Understanding Lenr Processes, Using Conventional Condensed Matter Physics

    Microsoft Academic Search

    Scott R. Chubb

    2006-01-01

    Conventional condensed matter physics provides a unifying framework for understanding low-energy nuclear reactions (LENRs) in solids. In the paper, standard many-body physics techniques are used to illustrate this fact. Specifically, the paper shows that formally the theories by Schwinger, Hagelstein, and Chubb and Chubb (C&C), all can be related to a common set of equations, associated with reaction rate and

  8. Sidestream condensate polishing for PWRs

    SciTech Connect

    Shor, S.W.W.; Yim, S.L.; Rios, J.; Liu, J.

    1986-06-01

    Condensate polishers are used in power plant condensate system to remove both particulate matter and ionized corrodents. Their conventional location is just downstream of the hotwell pumps (condensate pumps). Most polisher installations have enough flow capacity to polish 100% of the condensate. This inline configuration has some disadvantage, including a flow that varies with unit load and tends to disturb the polisher beds and reduce their effectiveness, and a potential for interrupting flow to the feedwater pumps. An alternate arrangement where water is extracted from either the condenser or the condensate system, polished and returned to the system, has been used in a few plants. Three different ways of doing this have been used: divide the condenser hotwell into two parts, one of which receives condensate from the tube bundles and the other of which is sheltered. Take unpolished condensate from the first part, purify it and return it to the other part from which the condensate pumps take suction; take unpolished condensate from one end of a divided header on the suction side of the hotwell pumps and after polishing it return it to the other end; and take unpolished condensate from a header on the discharge side of the condensate pumps, purify it and return it to the condensate system a short distance downstream. The three variants are analyzed in this report. It is concluded that the variant where the connections are on the discharge side of the condensate pumps is the most desirable for retrofitting, in all cases being far easier to retrofit than an inline polisher. In many cases it will be most desirable for new construction.

  9. The diagnostic accuracy of multi-frequency bioelectrical impedance analysis in diagnosing dehydration after stroke

    PubMed Central

    Kafri, Mohannad W.; Myint, Phyo Kyaw; Doherty, Danielle; Wilson, Alexander Hugh; Potter, John F.; Hooper, Lee

    2013-01-01

    Background Non-invasive methods for detecting water-loss dehydration following acute stroke would be clinically useful. We evaluated the diagnostic accuracy of multi-frequency bioelectrical impedance analysis (MF-BIA) against reference standards serum osmolality and osmolarity. Material/Methods Patients admitted to an acute stroke unit were recruited. Blood samples for electrolytes and osmolality were taken within 20 minutes of MF-BIA. Total body water (TBW%), intracellular (ICW%) and extracellular water (ECW%), as percentages of total body weight, were calculated by MF-BIA equipment and from impedance measures using published equations for older people. These were compared to hydration status (based on serum osmolality and calculated osmolarity). The most promising Receiver Operating Characteristics curves were plotted. Results 27 stroke patients were recruited (mean age 71.3, SD10.7). Only a TBW% cut-off at 46% was consistent with current dehydration (serum osmolality >300 mOsm/kg) and TBW% at 47% impending dehydration (calculated osmolarity ?295–300 mOsm/L) with sensitivity and specificity both >60%. Even here diagnostic accuracy of MF-BIA was poor, a third of those with dehydration were wrongly classified as hydrated and a third classified as dehydrated were well hydrated. Secondary analyses assessing diagnostic accuracy of TBW% for men and women separately, and using TBW as a percentage of lean body mass showed some promise, but did not provide diagnostically accurate measures across the population. Conclusions MF-BIA appears ineffective at diagnosing water-loss dehydration after stroke and cannot be recommended as a test for dehydration, but separating assessment by sex, and using TBW as a percentage of lean body weight may warrant further investigation. PMID:23839255

  10. Transcriptome sequencing and whole genome expression profiling of chrysanthemum under dehydration stress

    PubMed Central

    2013-01-01

    Background Chrysanthemum is one of the most important ornamental crops in the world and drought stress seriously limits its production and distribution. In order to generate a functional genomics resource and obtain a deeper understanding of the molecular mechanisms regarding chrysanthemum responses to dehydration stress, we performed large-scale transcriptome sequencing of chrysanthemum plants under dehydration stress using the Illumina sequencing technology. Results Two cDNA libraries constructed from mRNAs of control and dehydration-treated seedlings were sequenced by Illumina technology. A total of more than 100 million reads were generated and de novo assembled into 98,180 unique transcripts which were further extensively annotated by comparing their sequencing to different protein databases. Biochemical pathways were predicted from these transcript sequences. Furthermore, we performed gene expression profiling analysis upon dehydration treatment in chrysanthemum and identified 8,558 dehydration-responsive unique transcripts, including 307 transcription factors and 229 protein kinases and many well-known stress responsive genes. Gene ontology (GO) term enrichment and biochemical pathway analyses showed that dehydration stress caused changes in hormone response, secondary and amino acid metabolism, and light and photoperiod response. These findings suggest that drought tolerance of chrysanthemum plants may be related to the regulation of hormone biosynthesis and signaling, reduction of oxidative damage, stabilization of cell proteins and structures, and maintenance of energy and carbon supply. Conclusions Our transcriptome sequences can provide a valuable resource for chrysanthemum breeding and research and novel insights into chrysanthemum responses to dehydration stress and offer candidate genes or markers that can be used to guide future studies attempting to breed drought tolerant chrysanthemum cultivars. PMID:24074255

  11. Gravitational vacuum condensate stars

    PubMed Central

    Mazur, Pawel O.; Mottola, Emil

    2004-01-01

    A new final state of gravitational collapse is proposed. By extending the concept of Bose–Einstein condensation to gravitational systems, a cold, dark, compact object with an interior de Sitter condensate pv = -?v and an exterior Schwarzschild geometry of arbitrary total mass M is constructed. These regions are separated by a shell with a small but finite proper thickness ? of fluid with equation of state p = +?, replacing both the Schwarzschild and de Sitter classical horizons. The new solution has no singularities, no event horizons, and a global time. Its entropy is maximized under small fluctuations and is given by the standard hydrodynamic entropy of the thin shell, which is of the order kB?Mc/, instead of the Bekenstein–Hawking entropy formula, SBH = 4?kBGM2/c. Hence, unlike black holes, the new solution is thermodynamically stable and has no information paradox. PMID:15210982

  12. Sustainable production of acrylic acid: alkali-ion exchanged beta zeolite for gas-phase dehydration of lactic acid.

    PubMed

    Yan, Bo; Tao, Li-Zhi; Liang, Yu; Xu, Bo-Qing

    2014-06-01

    Gas-phase dehydration of lactic acid (LA) to acrylic acid (AA) was investigated over alkali-exchanged ? zeolite (M(x)Na(1-x)?, M=Li(+), K(+), Rb(+), or Cs(+)) of different exchange degrees (x). The reaction was conducted under varying conditions to understand the catalyst selectivity for AA production and trends of byproduct formation. The nature and exchange degree of M(+) were found to be critical for the acid-base properties and catalytic performance of the exchanged zeolite. K(x)Na(1-x)? of x=0.94 appeared to be the best performing catalyst whereas Li(x)Na(1-x)? and Na? were the poorest in terms of AA selectivity and yield. The AA yield as high as 61?mol?% (selectivity: 64?mol?%) could be obtained under optimized reaction conditions for up to 8?h over the best performing K0.94Na0.06?. The acid and base properties of the catalysts were probed, respectively by temperature-programmed desorption (TPD) of adsorbed NH3 and CO2, and were related to the electrostatic potentials of the alkali ions in the zeolite, which provided a basis for the discussion of the acid-base catalysis for sustainable AA formation from LA. PMID:24903259

  13. Potentially Prebiotic Syntheses of Condensed Phosphates

    NASA Technical Reports Server (NTRS)

    Keefe, Anthony D.; Miller, Stanley L.

    1996-01-01

    In view of the importance of a prebiotic source of high energy phosphates, we have investigated a number of potentially prebiotic processes to produce condensed phosphates from orthophosphate and cyclic trimetaphosphate from tripolyphosphate. The reagents investigated include polymerizing nitriles, acid anhydrides, lactones, hexamethylene tetramine and carbon suboxide. A number of these processes give substantial yields of pyrophosphate from orthophosphate and trimetaphosphate from tripolyphosphate. Although these reactions may have been applicable in local areas, they are not sufficiently robust to have been of importance in the prebiotic open ocean.

  14. Bose-Einstein Condensation

    SciTech Connect

    El-Sherbini, Th.M. [Physics Department, Faculty of Science, Cairo University, Giza (Egypt)

    2005-03-17

    This article gives a brief review of Bose-Einstein condensation. It is an exotic quantum phenomenon that was observed in dilute atomic gases for the first time in 1995. It exhibits a new state of matter in which a group of atoms behaves as a single particle. Experiments on this form of matter are relevant to many different areas of physics- from atomic clocks and quantum computing to super fluidity, superconductivity and quantum phase transition.

  15. Differential proteomics of dehydration and rehydration in bryophytes: evidence towards a common desiccation tolerance mechanism.

    PubMed

    Cruz DE Carvalho, Ricardo; Bernardes DA Silva, Anabela; Soares, Renata; Almeida, André M; Coelho, Ana Varela; Marques DA Silva, Jorge; Branquinho, Cristina

    2014-07-01

    All bryophytes evolved desiccation tolerance (DT) mechanisms during the invasion of terrestrial habitats by early land plants. Are these DT mechanisms still present in bryophytes that colonize aquatic habitats? The aquatic bryophyte Fontinalis antipyretica?Hedw. was subjected to two drying regimes and alterations in protein profiles and sucrose accumulation during dehydration and rehydration were investigated. Results show that during fast dehydration, there is very little variation in protein profiles, and upon rehydration proteins are leaked. On the other hand, slow dehydration induces changes in both dehydration and rehydration protein profiles, being similar to the protein profiles displayed by the terrestrial bryophytes Physcomitrella patens (Hedw.) Bruch and Schimp. and, to what is comparable with Syntrichia ruralis (Hedw.) F. Weber and D. Mohr. During dehydration there was a reduction in proteins associated with photosynthesis and the cytoskeleton, and an associated accumulation of proteins involved in sugar metabolism and plant defence mechanisms. Upon rehydration, protein accumulation patterns return to control values for both photosynthesis and cytoskeleton whereas proteins associated with sugar metabolism and defence proteins remain high. The current results suggest that bryophytes from different ecological adaptations may share common DT mechanisms. PMID:24393025

  16. Tracking the dehydration process of raw honey by synchronous two-dimensional near infrared correlation spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Guiyun; Sun, Xin; Huang, Yuping; Chen, Kunjie

    2014-11-01

    Though much attention is paid to honey quality assessment, few reports on characteristic of manually dehydrated honey have been found. The aim of this investigation is to track the dehydration process of raw honey using synchronous two-dimensional (2D) near infrared correlation spectroscopy. To minimize the impact of dehydration to honey quality, seventy-two honey samples from six different dehydration stages were obtained using drum wind drying method with temperature controlled at 40 °C. Their dynamic short-wave NIR spectra from 600 to 1100 nm were collected in the transmission mode from 10 to 50 °C with an increment of 5 °C and were analyzed using synchronous two-dimensional correlation method. Short-wave NIR spectral data has been exploited less than other NIR region for its weaker signal especially for water absorption's interference with useful information. The investigation enlarged the signal at this band using synchronous 2D correlation analysis, revealing the fingerprinting feature of rape honey and chaste honey during the artificial dehydration process. The results have shown that, with the help of 2D correlation analysis, this band can detect the variation of the second overtone of O-H and N-H groups vibration upon their H-bonds forming or collapsing resulted from the interactions between water and solute. The results have also shown that 2D-NIRS method is able to convert the tiny changes in honey constituents into the detectable fingerprinting difference, which provides a new method for assessing honey quality.

  17. CH2-units on (poly-)ethylene glycol radially dehydrate cytoplasm of resting skinned skeletal muscle.

    PubMed

    Kimura, Masako; Takemori, Shigeru

    2008-06-01

    Observing the optical cross-section and electron micrographs of mechanically skinned fibres of frog skeletal muscle, we found that ethylene glycols (EGs) of small (mono-, di-, tri- and tetra-EGs; M(r) 62-194) and medium (poly-EGs; M(r) 900 and 3350) molecular weights efficiently dehydrate the fibres to shrink them radially without microscopic inhomogeneity. The medium-sized poly-EGs at 30% weight/weight concentration absorbed almost all the evaporable water from the fibre. Passive tension measurement at near slack sarcomere spacing indicated that this dehydration by EGs did not accompany longitudinal fibre shrinkage. Chemically relevant fully hydric alcohols (glycerol, threitol, ribitol and mannitol; M(r) 92-182) showed no appreciable dehydrating ability on fibres. An intimate correlation was found between fibre dehydration and CH(2)-concentration of the solutions. Viscosity measurements indicated that the hydrodynamic radii of the alcohols were comparable to those of the small EGs. Therefore, hydrodynamic radii are not a primary determinant of the dehydrating ability. Additionally, CH(2)-concentration of EGs but not alcohols was found to correlate intimately with the measured viscosity of the bulk solution of EGs. These results suggested that the interaction between water molecules and CH(2)-units in crowded cytoplasm of skeletal muscle affects cytoplasm as a whole to realize anisotropic fibre shrinkage. PMID:18583358

  18. CH2-units on (poly-)ethylene glycol radially dehydrate cytoplasm of resting skinned skeletal muscle.

    PubMed

    Kimura, Masako; Takemori, Shigeru

    2008-01-01

    Observing the optical cross-section and electron micrographs of mechanically skinned fibres of frog skeletal muscle, we found that ethylene glycols (EGs) of small (mono-, di-, tri- and tetra-EGs; M(r) 62-194) and medium (poly-EGs; M(r) 900 and 3350) molecular weights efficiently dehydrate the fibres to shrink them radially without microscopic inhomogeneity. The medium-sized poly-EGs at 30% weight/weight concentration absorbed almost all the evaporable water from the fibre. Passive tension measurement at near slack sarcomere spacing indicated that this dehydration by EGs did not accompany longitudinal fibre shrinkage. Chemically relevant fully hydric alcohols (glycerol, threitol, ribitol and mannitol; M(r) 92-182) showed no appreciable dehydrating ability on fibres. An intimate correlation was found between fibre dehydration and CH(2)-concentration of the solutions. Viscosity measurements indicated that the hydrodynamic radii of the alcohols were comparable to those of the small EGs. Therefore, hydrodynamic radii are not a primary determinant of the dehydrating ability. Additionally, CH(2)-concentration of EGs but not alcohols was found to correlate intimately with the measured viscosity of the bulk solution of EGs. These results suggested that the interaction between water molecules and CH(2)-units in crowded cytoplasm of skeletal muscle affects cytoplasm as a whole to realize anisotropic fibre shrinkage. PMID:17977855

  19. Buffering limits plasma HCO3- dehydration when red blood cell anion exchange is inhibited.

    PubMed

    Gilmour, K M; Desforges, P R; Perry, S F

    2004-05-20

    Theory suggests that HCO3- dehydration in the plasma of rainbow trout is limited by both the absence of carbonic anhydrase (CA) activity and the low non-bicarbonate buffer capacity of the plasma (betaplasma). The potential for betaplasma to limit plasma HCO3- dehydration was assessed in rainbow trout in which HCO3- dehydration via the red blood cell (RBC) was inhibited using the anion exchange blocker 4,4'-diisothiocyanostilbene-2,2'-disulphonic acid (DIDS). DIDS administration reduced the rate of RBC HCO3- dehydration by 68-80% for at least 6h, resulting in the elevation of arterial CO2 tension (PaCO2) by 3.07 +/- 0.45 Torr (N = 6). Addition of bovine CA to the circulation of DIDS-treated trout caused PaCO2 to decrease significantly. This effect was increased significantly in rainbow trout in which betaplasma was elevated experimentally by intravascular injection of N-[2-hydroxyethyl]piperazine-N'-[2-ethanesulfonic acid] (HEPES), supporting the hypothesis that CA-catalysed HCO3- dehydration in the plasma of rainbow trout is limited by proton availability. PMID:15134665

  20. Transcriptional profiling of hexaploid wheat (Triticum aestivum L.) roots identifies novel, dehydration-responsive genes.

    PubMed

    Mohammadi, Mohsen; Kav, Nat N V; Deyholos, Michael K

    2007-05-01

    We used a long-oligonucleotide microarray to identify transcripts that increased or decreased in abundance in roots of dehydration-tolerant hexaploid bread wheat, in response to withholding of water. We observed that the major classes of dehydration-responsive genes (e.g. osmoprotectants, compatible solutes, proteases, glycosyltransferases/hydrolases, signal transducers components, ion transporters) were generally similar to those observed previously in other species and osmotic stresses. More specifically, we highlighted increases in transcript expression for specific genes including those putatively related to the synthesis of asparagine, trehalose, oligopeptide transporters, metal-binding proteins, the gamma-aminobutyric acid (GABA) shunt and transcription factors. Conversely, we noted a decrease in transcript abundance for diverse classes of glutathione and sulphur-related enzymes, specific amino acids, as well as MATE-efflux carrier proteins. From these data, we identified a novel, dehydration-induced putative AP2/ERF transcription factor, which we predict to function as a transcriptional repressor. We also identified a dehydration-induced 'little protein' (LitP; predicted mass: 8 kDa) that is highly conserved across spermatophytes. Using qRT-PCR, we compared the expression patterns of selected genes between two related wheat genotypes that differed in their susceptibility to dehydration, and confirmed that these novel genes were highly inducible by water limitation in both genotypes, although the magnitude of induction differed. PMID:17407540

  1. Role of the ERK signaling pathway in regulating vasopressin secretion in dehydrated rats.

    PubMed

    Nikitina, L S; Dorofeeva, N A; Kirillova, O D; Korotkov, A A; Glazova, M; Chernigovskaya, E V

    2014-04-01

    Dehydration activates the vasopressinergic system of the hypothalamus. We analyzed the effects of dehydration induced by water deprivation for 3 days on the activities of ERK1/2 and transcription factors, Elk1 and cAMP response element-binding protein (CREB) in vasopressinergic neurons, as well as the distribution and level of the motor protein, kinesin, in the hypothalamo-neurohypophyseal system. We showed that dehydration resulted in enhanced vasopressin (VP) expression and activation of CREB, and increased the activity of the MEK/ERK/Elk1 pathway in magnocellular neurons of the supraoptic nucleus. The activation of VP secretion was associated also with accumulation of phospho-ERK1/2 in the VP-ergic terminals of the posterior lobe of the pituitary. Analysis of the amount and distribution of kinesin and SNAP25, the proteins associated with transport and secretion, demonstrated that dehydration enhanced kinesin content in the perikarya of magnocellular neurons in the supraoptic nucleus and decreased kinesin and SNAP25 levels in the posterior pituitary. ERK1/2 and ERK1/2-dependent transcription factors, Elk1 and CREB, participate in the regulation of dehydration-evoked VP expression. We propose that ERK1/2 and kinesin participate in regulation of anterograde transport of VP dense core vesicles. PMID:24053164

  2. Anomalous dehydration of the TTL during January 2013: evidence from balloon, aircraft and satellite observations

    NASA Astrophysics Data System (ADS)

    Khaykin, Sergey; Pommereau, Jean-Pierre; Hauchecorne, Alain; Rivière, Emmanuel; Amarouche, Nadir; Ghysel, Melanie; Wienhold, Frank; Held, Gerard; Evan, Stephanie; Thornberry, Troy; Rollins, Andrew; Fahey, David; Vömel, Holger; Fujiwara, Masatomo; Rosenlof, Karen

    2015-04-01

    The goal of this study is to comprehensively document an anomalous dehydration of the Tropical Tropopause Layer (TTL) related to a major Sudden Stratospheric Warming (SSW) in January 2013. The analysis involves the data of balloon soundings of water vapour at various tropical locations using FLASH-B, Pico-SDLA and CFH hygrometers as well as NOAA Water instrument flown onboard high-altitude Global Hawk aircraft. Simultaneous water vapour and backscatter measurements by FLASH-B and COBALD sondes provide information on tropopause clouds formation process. Satellite observations of water vapour by Aura MLS are used to derive the deviation from climatological values. Trajectory modeling is applied for locating the dehydration source spots. Spatiotemporal evolution of dehydration at different scales is characterized after combining the consistent in situ and satellite water vapour observations. All data sets provide evidence of rapid and severe dehydration of the TTL throughout the tropical belt shortly after the onset of SSW. In situ measurements around the Cold Point Tropopause (CPT) show up to 2 ppmv of negative deviation from MLS 10-year climatology with extreme water mixing ratios below 1 ppmv in the Western Pacific region. The TTL dehydration case of 2013 is compared with previous similar occurrences and the role of extra-tropical dynamics in setting the global stratospheric water budget through thermal response in the TTL is pointed out

  3. Airway Surface Dehydration Aggravates Cigarette Smoke-Induced Hallmarks of COPD in Mice

    PubMed Central

    Seys, Leen J. M.; Verhamme, Fien M.; Dupont, Lisa L.; Desauter, Elke; Duerr, Julia; Seyhan Agircan, Ayca; Conickx, Griet; Joos, Guy F.; Brusselle, Guy G.

    2015-01-01

    Introduction Airway surface dehydration, caused by an imbalance between secretion and absorption of ions and fluid across the epithelium and/or increased epithelial mucin secretion, impairs mucociliary clearance. Recent evidence suggests that this mechanism may be implicated in chronic obstructive pulmonary disease (COPD). However, the role of airway surface dehydration in the pathogenesis of cigarette smoke (CS)-induced COPD remains unknown. Objective We aimed to investigate in vivo the effect of airway surface dehydration on several CS-induced hallmarks of COPD in mice with airway-specific overexpression of the ?-subunit of the epithelial Na+ channel (?ENaC). Methods ?ENaC-Tg mice and wild-type (WT) littermates were exposed to air or CS for 4 or 8 weeks. Pathological hallmarks of COPD, including goblet cell metaplasia, mucin expression, pulmonary inflammation, lymphoid follicles, emphysema and airway wall remodelling were determined and lung function was measured. Results Airway surface dehydration in ?ENaC-Tg mice aggravated CS-induced airway inflammation, mucin expression and destruction of alveolar walls and accelerated the formation of pulmonary lymphoid follicles. Moreover, lung function measurements demonstrated an increased compliance and total lung capacity and a lower resistance and hysteresis in ?ENaC-Tg mice, compared to WT mice. CS exposure further altered lung function measurements. Conclusions We conclude that airway surface dehydration is a risk factor that aggravates CS-induced hallmarks of COPD. PMID:26066648

  4. Simulation of mass transfer during osmotic dehydration of apple: a power law approximation method

    NASA Astrophysics Data System (ADS)

    Abbasi Souraki, B.; Tondro, H.; Ghavami, M.

    2014-10-01

    In this study, unsteady one-dimensional mass transfer during osmotic dehydration of apple was modeled using an approximate mathematical model. The mathematical model has been developed based on a power law profile approximation for moisture and solute concentrations in the spatial direction. The proposed model was validated by the experimental water loss and solute gain data, obtained from osmotic dehydration of infinite slab and cylindrical shape samples of apple in sucrose solutions (30, 40 and 50 % w/w), at different temperatures (30, 40 and 50 °C). The proposed model's predictions were also compared with the exact analytical and also a parabolic approximation model's predictions. The values of mean relative errors respect to the experimental data were estimated between 4.5 and 8.1 %, 6.5 and 10.2 %, and 15.0 and 19.1 %, for exact analytical, power law and parabolic approximation methods, respectively. Although the parabolic approximation leads to simpler relations, the power law approximation method results in higher accuracy of average concentrations over the whole domain of dehydration time. Considering both simplicity and precision of the mathematical models, the power law model for short dehydration times and the simplified exact analytical model for long dehydration times could be used for explanation of the variations of the average water loss and solute gain in the whole domain of dimensionless times.

  5. Asymmetric condensed dark matter

    E-print Network

    Aguirre, Anthony

    2015-01-01

    We explore the viability of a boson dark matter candidate with an asymmetry between the number densities of particles and antiparticles. A simple thermal field theory analysis confirms that, under certain general conditions, this component would develop a Bose-Einstein condensate in the early universe that, for appropriate model parameters, could survive the ensuing cosmological evolution until now. The condensation of a dark matter component in equilibrium with the thermal plasma is a relativistic process, hence the amount of matter dictated by the charge asymmetry is complemented by a hot relic density frozen out at the time of decoupling. Contrary to the case of ordinary WIMPs, dark matter particles in a condensate can be very light, $10^{-22}\\,{\\rm eV} \\lesssim m \\lesssim 10^2\\,{\\rm eV}$; the lower limit arises from constraints on small-scale structure formation, while the upper bound ensures that the density from thermal relics is not too large. Big-Bang nucleosynthesis constrains the temperature of deco...

  6. Temperature dependent elasticity and damping in dehydrated sandstone

    NASA Astrophysics Data System (ADS)

    Darling, T. W.; Struble, W.

    2013-12-01

    Work reported previously at this conference, outlining our observation of anomalously large elastic softening and damping in dehydrated Berea sandstone at elevated temperatures, has been analysed to study shear and compressional effects separately. Modeling of the sample using COMSOL software was necessary to identify modes, as the vibration spectrum of the sample is poorly approximated by a uniform isotropic solid. The first torsional mode of our evacuated, dry, core softens at nearly twice the rate of Young's modulus modes (bending and compressional) and is also damped nearly twice as strongly as temperature increases. We consider two possible models for explaining this behavior, based on the assumption that the mechanical properties of the sandstone are dominated by the framework of quartz grains and polycrystalline cementation, neglecting initially the effects of clay and feldspar inclusions. The 20cm x 2.54cm diameter core is dry such that the pressure of water vapor in the experiment chamber is below 1e-6 Torr at 70C, suggesting that surface water beyond a small number of monolayers is negligible. Our models consider (1) enhanced sliding of grain boundaries in the cementation at elevated temperature and reduced internal water content, and (2) strain microcracking of the cementatioin at low water content due to anisotropic expansion in the quartz grains. In model (1) interfaces parallel to polyhedral grain surfaces were placed in the cement bonds and assigned frictional properties. Model (2) has not yet been implemented. The overall elasticity of a 3-D several-grain model network was determined by modeling quasistatic loading and measuring displacements. Initial results with a small number of grains/bonds suggests that only the first model provides softening and damping for all the modes, however the details of the effects of defect motioin at individual interfaces as the source for the frictional properties is still being evaluated. Nonlinear effects are experimentally observed at lower temperatures but damping at higher temperatures reduces the strain amplitude so that nonlinearity is not apparent, but may still be present. This work is supported by grant #DE-FG02-11ER16218 from the Geosciences Division of the DOE Office of Basic Energy Sciences.

  7. Freeze Enhanced Halate Halide Reactions

    NASA Astrophysics Data System (ADS)

    Newberg, J. T.; Weaver, K.; Broderick, A.

    2014-12-01

    Relatively little is known about halate ion species (XO3-; X = I, Br, Cl) in atmospheric condensed phases. It was initial thought that iodate was a terminal stable species upon iodide oxidation. However, it is becoming increasingly recognized that reactions involving iodate can lead to reactive iodine, and this chemistry is accelerated under acidic conditions. The environmental concentrations and chemistry of bromate and chlorate are largely unexplored in environmental ices. We present results from a series of aqueous phase halate ion reactions with halides under acidic conditions, showing that the kinetics are strongly enhanced upon freezing. The products of these reactions are reactive halogens, which have important implications to marine boundary layer chemistry.

  8. Control of VOCs emissions by condenser pre-treatment in a semiconductor fab.

    PubMed

    Lin, Yu-Chih; Chang, Feng-Tang; Bai, Hsunling; Pei, Bau-Shei

    2005-04-11

    The performance of a modified design of local condensers to pre-treat a variety of volatile organic compounds (VOCs) emitted from the stripping process of a semiconductor fab was tested in this study. The reaction temperature of the condensers was controlled at around 10 degrees C, it is relatively higher than the traditional condenser reaction temperature. Both VOCs and water vapors were condensed and formed liquid films. This resulted in an enhancement of the VOCs removals, especially for VOCs of high boiling points or solubility. This can help to prevent the follow up zeolite concentrator from damage. The performance of the integrated system of condenser/zeolite concentrator could, therefore, remain highly efficient for a longer operation time. Its annualized cost would also be lower than installing the zeolite concentrator only. PMID:15811658

  9. Highly condensed epoxy-oligosiloxane-based hybrid material for transparent low-k dielectric coatings.

    PubMed

    Yang, Seungcheol; Kwak, Seung-Yeon; Jin, Jungho; Bae, Byeong-Soo

    2009-07-01

    A highly condensed epoxy-oligosiloxane resin was synthesized using a sol-gel condensation reaction of (3-glycidoxypropyl)trimethoxysilane and diphenylsilanediol in the presence of solvent. A higher degree of condensation and a larger molecular size of oligosiloxanes were achieved compared to a condensation reaction without the addition of a solvent. The epoxy-hybrimer coating film was fabricated by the spin coating and thermal curing of the synthesized oligosiloxane resin. The leakage current density and the dielectric constant decreased from 25.9 to 7.6 nA cm(-2) and from 3.16 to 3.03, respectively, by using the solvent in the preparation. The hybrimer coating film of a highly condensed oligosiloxane resin had a high transmittance of over 90% in a wavelength between 300 and 800 nm. Thus, the epoxy-hybrimer coating film can be utilized as the passivation layer in the thin-film transistor. PMID:20355965

  10. Autophagy in Antarctica: combating dehydration stress in the world's southernmost insect.

    PubMed

    Teets, Nicholas M; Denlinger, David L

    2013-04-01

    The midge Belgica antarctica is the only insect endemic to Antarctica and has the southernmost range of any insect. In its natural environment, B. antarctica frequently faces desiccating conditions, as environmental water is frozen for up to 9 months annually. The molecular mechanisms by which B. antarctica tolerates extreme dehydration are poorly understood, but recent work from our laboratory reports genome-wide expression changes in response to extreme dehydration (~40% water loss), the first genome-scale transcriptome reported for an Antarctic animal. Among transcripts differentially regulated during dehydration, there is coordinated upregulation of numerous genes involved in autophagy, including genes responsible for autophagosome synthesis and autophagy-associated transcription factors. Also, several genes and pathways that interact with and regulate autophagy, e.g., sestrins and proteasomal genes, are concurrently upregulated. This suggests that autophagy and related processes are key elements regulating stress tolerance in this extreme environment. PMID:23380735

  11. 1H NMR study of rehydration/dehydration and water mobility in ?-cyclodextrin.

    PubMed

    Pajzderska, A; Czarnecki, P; Mielcarek, J; W?sicki, J

    2011-04-01

    The processes of dehydration and rehydration of ?-cyclodextrin were studied by analysis of the (1)H NMR (nuclear magnetic resonance) line shape. Dehydration was carried in an open ampoule as a function of temperature and above 400 K total dehydration of ?-cyclodextrin was observed. This result was confirmed by the thermogravimetry (TG) measurements. Rehydration was studied as a function of time at room temperature. After 40 days, ?-cyclodextrin was found to absorb eight water molecules. The analysis of temperature changes in the shape of the (1)H NMR line of ?-cyclodextrin kept in a closed ampoule and its dielectric measurements provided information on the mobility of water molecules. The water molecules were found to perform complex molecular motions, that is, reorientational jumps below 200K and additionally, translational motion (diffusion) above 200K. PMID:21333279

  12. Concentration- and dehydration-dependent structural transitions in poly- L-lysine

    NASA Astrophysics Data System (ADS)

    Shanmugam, Ganesh; Polavarapu, Prasad L.

    2008-11-01

    The structural changes in poly- L-lysine (PLL), investigated as a function of simultaneous changes in concentration and pH, revealed a transition from right handed ?-helical to left handed poly- L-proline II (PP II)-type helical structure. The PPII-type structure of PLL in solution state was not influenced by the addition of sugars (trehalose or sucrose). The structure of PLL changes from PPII-type in solution state to ?-sheet in the dehydrated film state. In the presence of trehalose at PLL-trehalose mass ratio of 1:0.5, the structure of PLL changes from PPII-type in solution to a mixture of ?-helix + ?-sheet in the dehydrated film state. In the presence of trehalose at PLL-trehalose mass ratio of 1:1, the PPII-type structure of PLL in solution is maintained in the dehydrated film state.

  13. Improvement of Freezing Quality of Food by Pre-dehydration with Microwave-Vacuum Drying

    NASA Astrophysics Data System (ADS)

    Hamidi, Nurkholis; Tsuruta, Takaharu

    Partial dehydration by microwave vacuum drying has been applied to tuna, oyster and mackerel prior to freezing in order to reduce quality damages due to freezing and thawing. Samples were dehydrated at pressure of 4kPa and temperature lower than 25°C. Two cooling conditions were tested in the experiment by using the freezing chamber of temperatures -20°C and -80°C. The experimental results showed that decreasing the water content in tuna could lower the freezing point temperature and made the freezing time shorter. It was also found that removing some water was effective to reduce the size of ice crystal and the drip loss in mackerel. After thawing, the pre-dehydrated mackerel showed better microstructure than that frozen without pre-treatment. Furthermore, the sensory tests have been done by a group of panelist for the evaluation on aroma, flavor, and general acceptability of mackerels.

  14. Effect of hydration and dehydration cycles on seed germination of Aster kantoensis (Compositae)

    Microsoft Academic Search

    Mitsuko Kagaya; Takashi Tani; Naoki Kachi

    2005-01-01

    Seeds of Aster kantoensis Kitamura (Compositae) were experimentally exposed to different cycles of hydration and dehydration: 3H1D (cycles of 3-d hydration and 1-d dehydration periods), 2H3D, 2H1D, 1H3D, 1H2D, and 1H1D. Under continuous hydration (control), all viable seeds germinated within 9 d. However, all viable seeds ex- posed to the 3H1D, 2H3D, and 2H1D cycles germinated within 36, 50, and

  15. Dehydration is the first step in the bioactivation of haloperidol to its pyridinium metabolite.

    PubMed

    Fang, J; Gorrod, J W

    1991-12-01

    Haloperidol was found to have a similar metabolic pathway to that of the neurotoxin N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in mice microsomal preparations. The 1,2,3,6-tetrahydropyridine derivative of haloperidol was detected in NADPH-fortified metabolic incubation mixtures of haloperidol. Incubation of this dehydrated haloperidol produced the pyridinium metabolite. These metabolites were confirmed by comparison with synthesised compounds using HPLC and HPLC-MS. Dehydration of an alcohol to a double bond represents a novel metabolic pathway. This novel metabolic pathway indicates a MPTP-like mechanism for the Parkinsonism observed with haloperidol in clinical use. PMID:1755019

  16. Overpressure Caused by the Smectite Dehydration Influences on the triggering of fault slip

    NASA Astrophysics Data System (ADS)

    Lin, Wen-Sheng; Liu, Chen-Wuing; Chang, Han-Yuan

    2015-04-01

    Overpressure, which is pore fluid pressure higher than hydrostatic pressure, is observed in numerous mechanical processes along major faults. Many investigations currently show that the pore fluid pressure has been observed to influence the thrust fault strength and slip behavior and updip limit of the seismogenic zone. Clay dehydration is one key control on overpressure generation under undrained condition in thermal pressurization processes. Increasing pressure and temperature with depth depending on the local geological setting and conditions can cause clay dehydration which has been proposed as an explanation for the generation of overpressure. However, study about the effect of excess pore pressure caused by clay dehydration on the triggering of earthquake is seldom addressed in Taiwan. In fault zones like the Chelungpu Fault, clay minerals are abundant in the fault gouge. Therefore, to quantify the effect of overpressure caused by clay dehydration on the triggering of earthquake under undrained condition, we adopt the chemical thermodynamic model and chemical kinetic model to calculate the amount of water expelled from clay dehydration; derive the three-dimensional governing equation of groundwater flow with clay dehydration varied with pressure and temperature; follow the Coulomb-Mohr frictional failure model of earthquake occurrence to evaluate the influence of the pore pressure on the change of effective Coulomb stress. Finally, development of numerical model to simulate the effect of excess pore pressure caused by clay dehydration on the coulomb failure stress coupled thermal-hydraulic-mechanical-chemical has been performed. Moreover, field application with numerical model to quantify analysis of the effect of overpressure caused by clay dehydration on the triggering of earthquake has been progressed. Coulomb stress increases of ?0.01 MPa have been shown to be associated with seismicity rate increase and in many cases triggering earthquakes. The results have shown the safety analysis of earthquake slip in the clay-rich gouge of fault zones. In addition, the study has been proven to be a feasible examining tool for evaluation of overpressure influence on triggering of earthquake, especially when considering faults with abundant clay minerals of smectite.

  17. Reactions Between Water Soluble Organic Acids and Nitrates in Atmospheric Aerosols: Recycling of Nitric Acid and Formation of Organic Salts

    SciTech Connect

    Wang, Bingbing; Laskin, Alexander

    2014-03-25

    Atmospheric particles often include a complex mixture of nitrate and secondary organic materials accumulated within the same individual particles. Nitrate as an important inorganic component can be chemically formed in the atmosphere. For instance, formation of sodium nitrate (NaNO3) and calcium nitrate Ca(NO3)2 when nitrogen oxide and nitric acid (HNO3) species react with sea salt and calcite, respectively. Organic acids contribute a significant fraction of photochemically formed secondary organics that can condense on the preexisting nitrate-containing particles. Here, we present a systematic microanalysis study on chemical composition of laboratory generated particles composed of water soluble organic acids and nitrates (i.e. NaNO3 and Ca(NO3)2) investigated using computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and Fourier transform infrared micro-spectroscopy (micro-FTIR). The results show that water-soluble organic acids can react with nitrates releasing gaseous HNO3 during dehydration process. These reactions are attributed to acid displacement of nitrate with weak organic acids driven by the evaporation of HNO3 into gas phase due to its relatively high volatility. The reactions result in significant nitrate depletion and formation of organic salts in mixed organic acids/nitrate particles that in turn may affect their physical and chemical properties relevant to atmospheric environment and climate. Airborne nitrate concentrations are estimated by thermodynamic calculations corresponding to various nitrate depletions in selected organic acids of atmospheric relevance. The results indicate a potential mechanism of HNO3 recycling, which may further affect concentrations of gas- and aerosol-phase species in the atmosphere and the heterogeneous reaction chemistry between them.

  18. Self-condensation of activated dinucleotides on polynucleotide templates with alternating sequences

    NASA Technical Reports Server (NTRS)

    Lohrmann, R.; Orgel, L. E.

    1979-01-01

    Substantial quantities of the alternating polymers poly(U-G) and poly(C-A) have been prepared and used as templates for the self-condensation of ImpApC, ImpCpA, ImpGpU and ImpUpG. It is found that the condensation of ImpGpu and ImpUpG on poly(C-A) is efficient, the condensation of ImpCpA on poly(U-G) is moderately efficient, while the condensation of ImpApC on poly(U-C) proceeds poorly. In many cases, the product is predominantly 3'-5'-linked. These reactions demonstrate unequivocally, for the first time, that template-directed reactions occur in double-helical structures. Furthermore, they describe for the first time a pair of reactions in which each of two complementary polymers facilitates the synthesis of the other. The prebiotic significance of these findings is discussed.

  19. Use of Isopropyl Alcohol in Histological Assays: Dehydration of Tissue, Enbessing into Paraffin, and Processing of Paraffin Sections

    Microsoft Academic Search

    I. V. Viktorov; S. S. Proshin

    2003-01-01

    Isopropyl alcohol (isopropanol) can be used as a substitute for ethyl alcohol in tissue dehydration during embedding into paraffin and dehydration of stained sections. The use of isopropyl alcohol during paraffinization allows us to exclude treatment with intermediate solvents of paraffin (chloroform, xylene, and benzene), which reduces the degree of tissue compaction and simplifies and accelerates histological assay.

  20. GLYCOL DEHYDRATOR BTEX AND VOC EMISSIONS TESTING RESULTS AT TWO UNITS IN TEXAS AND LOUISIANA - VOLUME II. APPENDICES

    EPA Science Inventory

    The report gives results of the collection of emissions tests data at two triethylene glycol (TEG) units to provide data for comparison to GRI-GLYCalc, a computer program developed to estimate emissions from glycol dehydrators. (NOTE: Glycol dehydrators are used in the natural ga...

  1. GLYCOL DEHYDRATOR BTEX AND VOC EMISSIONS TESTING RESULTS AT TWO UNITS IN TEXAS AND LOUISIANA - VOLUME I. TECHNICAL REPORT

    EPA Science Inventory

    The report gives results of the collection of emissions tests data at two triethylene glycol (TEG) units to provide data for comparison to GRI-GLYCalc, a computer program developed to estimate emissions from glycol dehydrators. (NOTE: Glycol dehydrators are used in the natural ga...

  2. GLYCOL DEHYDRATOR BTEX AND VOC EMISSIONS TESTING RESULTS AT TWO UNITS IN TEXAS AND LOUISIANA VOL. II: APPENDICES

    EPA Science Inventory

    The report gives results of the collection of emissions test data st two triethylene glycol units to provide data for the comparison to GRI-GLYCalc, a computer program developed to estimate emissions from glycol dehydrators. [NOTE: Glycol dehydrators are used in the natural gas i...

  3. GLYCOL DEHYDRATOR BTEX AND VOC EMISSIONS TESTING RESULTS AT TWO UNITS IN TEXAS AND LOUISIANA VOL. I: TECHNICAL REPORT

    EPA Science Inventory

    The report gives results of the collection of emissions tests data at two triethylene glycol units to provide data for comparison to GRI-GLYCalc, a computer program developed to estimate emissions from glycol dehydrators. (NOTE: Glycol dehydrators are used in the natural gas indu...

  4. Evaluation of in situ smectite dehydration as a pore water freshening mechanism in the Nankai Trough, offshore southwest Japan

    Microsoft Academic Search

    Demian M. Saffer; Alexander W. McKiernan

    2009-01-01

    Pore water freshening has been observed within sediments near the trench at numerous subduction zones. Constraining the relative contributions of long-distance updip flow of freshened fluids and in situ clay dehydration holds important implications for margin-scale fluid flow but remains unresolved because the evolution of pore water chemistry expected due to in situ clay dehydration and the budget of fresh

  5. Dehydration-induced cross tolerance of Belgica antarctica larvae to cold and heat is facilitated by trehalose accumulation

    E-print Network

    Lee Jr., Richard E.

    Dehydration-induced cross tolerance of Belgica antarctica larvae to cold and heat is facilitated Antarctica Midge Larvae of the Antarctic midge, Belgica antarctica (Diptera: Chironomidae), are frequently that changes in temperature tolerance in B. antarctica are linked to the rate and severity of dehydration

  6. Steam Condensation Induced Waterhammer 

    E-print Network

    Kirsner, W.

    2000-01-01

    of heat. Wayne was knocked down and stunned by the scalding water spraying from the valve. Egress via the manhole exit was cut offby steam spraying from the valve. The only way out appeared to be through the material passouts constructed into the roof... exceed 1000 psi. This is enough pressure to fracture a cast iron valve. blowout a steam gasket, or burst an accordion type expansion joint. And. in fact. failure ofeach ofthese compo nents in separate condensation induced water hammer accidents has...

  7. Confinement Contains Condensates

    SciTech Connect

    Brodsky, Stanley J.; Roberts, Craig D.; Shrock, Robert; Tandy, Peter C.

    2012-03-12

    Dynamical chiral symmetry breaking and its connection to the generation of hadron masses has historically been viewed as a vacuum phenomenon. We argue that confinement makes such a position untenable. If quark-hadron duality is a reality in QCD, then condensates, those quantities that have commonly been viewed as constant empirical mass-scales that fill all spacetime, are instead wholly contained within hadrons; i.e., they are a property of hadrons themselves and expressed, e.g., in their Bethe-Salpeter or light-front wave functions. We explain that this paradigm is consistent with empirical evidence, and incidentally expose misconceptions in a recent Comment.

  8. Exhaled breath condensate: an overview.

    PubMed

    Davis, Michael D; Montpetit, Alison; Hunt, John

    2012-08-01

    Exhaled breath condensate (EBC) is a promising source of biomarkers of lung disease. EBC may be thought of either as a body fluid or as a condensate of exhaled gas. There are 3 principal contributors to EBC: variable-sized particles or droplets that are aerosolized from the airway lining fluid, distilled water that condenses from gas phase out of the nearly water-saturated exhalate, and water-soluble volatiles that are exhaled and absorbed into the condensing breath. The nonvolatile constituents and the water-soluble volatile constituents are of particular interest. Several key issues are discussed in this article. PMID:22877615

  9. Insights into the Mechanism of Type I Dehydroquinate Dehydratases from Structures of Reaction Intermediates*

    PubMed Central

    Light, Samuel H.; Minasov, George; Shuvalova, Ludmilla; Duban, Mark-Eugene; Caffrey, Michael; Anderson, Wayne F.; Lavie, Arnon

    2011-01-01

    The biosynthetic shikimate pathway consists of seven enzymes that catalyze sequential reactions to generate chorismate, a critical branch point in the synthesis of the aromatic amino acids. The third enzyme in the pathway, dehydroquinate dehydratase (DHQD), catalyzes the dehydration of 3-dehydroquinate to 3-dehydroshikimate. We present three crystal structures of the type I DHQD from the intestinal pathogens Clostridium difficile and Salmonella enterica. Structures of the enzyme with substrate and covalent pre- and post-dehydration reaction intermediates provide snapshots of successive steps along the type I DHQD-catalyzed reaction coordinate. These structures reveal that the position of the substrate within the active site does not appreciably change upon Schiff base formation. The intermediate state structures reveal a reaction state-dependent behavior of His-143 in which the residue adopts a conformation proximal to the site of catalytic dehydration only when the leaving group is present. We speculate that His-143 is likely to assume differing catalytic roles in each of its observed conformations. One conformation of His-143 positions the residue for the formation/hydrolysis of the covalent Schiff base intermediates, whereas the other conformation positions the residue for a role in the catalytic dehydration event. The fact that the shikimate pathway is absent from humans makes the enzymes of the pathway potential targets for the development of non-toxic antimicrobials. The structures and mechanistic insight presented here may inform the design of type I DHQD enzyme inhibitors. PMID:21087925

  10. Carbon Dioxide Exchange at the Air–Sea Interface: Flux Augmentation by Chemical Reaction

    Microsoft Academic Search

    J. A. Quinn; N. C. Otto

    1971-01-01

    Numerical results for typical ocean conditions indicate that for film thicknesses less than, say, 400tz. oceanic exchange is not influenced by the hydration\\/dehydration reactions of dissolved carbon dioxide. This conclusion is in substantial agreement with the approximate analysis of Bolin [1960]. However, if suitable catalysts are present in the ocean (there is recent evidence to suggest that this may be

  11. Low Energy Nuclear Reactions?

    E-print Network

    CERN. Geneva; Faccini, R.

    2014-01-01

    After an introduction to the controversial problem of Low Energy Nuclear Reactions (LENR) catalyzed by neutrons on metallic hydride surfaces we present the results of an experiment, made in collaboration with ENEA Labs in Frascati, to search neutrons from plasma discharges in electrolytic cells. The negative outcome of our experiment goes in the direction of ruling out those theoretical models expecting LENR to occur in condensed matter systems under specific conditions. Our criticism on the theoretical foundations of such models will also be presented.

  12. Pentafluorophenylammonium triflate (PFPAT): an efficient, practical, and cost-effective catalyst for one-pot condensation of ?-naphthol, aldehydes and cyclic 1,3-dicarbonyl compounds.

    PubMed

    Khaksar, Samad; Behzadi, Nosratollah

    2012-12-01

    A pentafluorophenylammonium triflate (PFPAT) catalyst (10 mol%) efficiently promoted one-pot condensation of ?-naphthol, aldehydes, and cyclic 1,3-dicarbonyl compounds in good to excellent yield under mild reaction conditions. These catalytic condensations have advantages from the viewpoint of green chemistry. PFPAT organocatalyst is air-stable, cost-effective, easy to handle, and easily removed from the reaction mixtures. PMID:22963336

  13. Thermochemical modeling of thermite-type reactions

    SciTech Connect

    Behrens, R.G.; Hansen, G.P.

    1985-01-01

    Purpose of this work was to use thermodynamic modeling to study the chemistry associated with the synthesis of TiB/sub 2/, SiC, and TiC by thermite-type reactions. Side reactions (including vaporization reactions) compete with the primary reaction and thus decrease the yield of a desired product. The relative importance of side reactions is governed in part by the thermodynamic stabilities of byproducts relative to the stabilities of the major products. The computer program SOLGASMIX was used to compute condensed phase stability diagrams for the four chemical systems.

  14. [Status of the coagulant and anticoagulant systems of the blood in experimental acute intestinal dehydration of the body].

    PubMed

    Pastorova, V E; Esartiia, D T

    1981-09-01

    Acute intestinal dehydration induced in rabbits by administration into the stomach of 50 ml of castor oil produced hypercoagulation in all stages of dehydration. Hypercoagulation increased as the degree of body dehydration rose. In the first and second stages of dehydration (body mass loss from 1 to 5 and from 6 to 10%, respectively), the development of hypercoagulation was accompanied by the activation of anticoagulative system function: the increase in the total and non-enzymatic fibrinolytic activity and reduction in the activity of antiplasmins. At a stronger degree of dehydration (body mass loss from 11 to 15%) the increase of the enzymatic fibrinolytic activity was negligible, while the activation of non-enzymatic fibrinolysis was absent. PMID:7295984

  15. Serpentinization and dehydration in the upper mantle beneath Fuerteventura (eastern Canary Islands): Evidence from mantle xenoliths

    NASA Astrophysics Data System (ADS)

    Abu El-Rus, M. A.; Neumann, E.-R.; Peters, V.

    2006-06-01

    Mantle xenoliths from Fuerteventura (spinel-bearing harzburgites, dunites, and rare lherzolites and wehrlites) in the easternmost part of the Canary Islands chain, are highly deformed and show a wide range in textures from protogranular and porphyroclastic with olivine and orthopyroxene porphyroclasts, to rocks with "fibrous textures" (no orthopyroxene porphyroclasts, large, porous clusters of fibrous orthopyroxene, olivine porphyroclasts criss-crossed by stringy trails of fibrous orthopyroxene and fluid inclusions). The whole group of xenoliths covers a wider compositional range (e.g. Fo 86.6-92.7, 0.18-0.44 wt.% NiO, and up to 0.25 wt.% CaO in olivine; < 0.01-2.5 wt.% TiO 2 and 0.7-5.5 wt.% Al 2O 3 in clinopyroxenes in harzburgites and lherzolites, and relatively Ti-Fe 3+-rich spinels in some rocks). Rocks with orthopyroxene porphyroclasts cover a restricted compositional range typical of depleted oceanic peridotites (e.g. Fo 90.7-91.4, 0.36-0.41 wt.% NiO, and < 0.10 wt.% CaO in cores of olivine porphyroclasts; ? 0.12 wt.% TiO 2, 1.0-1.8 wt.% Al 2O 3 in clinopyroxene; low Ti and Fe 3+, and high Cr in spinel). These rocks are interpreted as pieces of the highly refractory oceanic lithosphere that accreted to the oldest oceanic crust in this part of the Atlantic Ocean, later modified by different processes. This mantle was highly depleted due to melt extraction, and had a composition similar to that of the most refractory peridotites collected along the Mid-Atlantic Ridge. Also the oceanic mantle beneath the other Canary Islands appears to have had similar composition before the onset of the Canary Islands magmatism. The "fibrous textures" in many xenoliths from Fuerteventura are interpreted as the results of partial serpentinization, later followed by heating and dehydration during the formation of Fuerteventura. The Fuerteventura magmatism has also caused metasomatism and reactions in the lithospheric mantle beneath Fuerteventura, leading to decreased Si and increased Fe+Ca+Na±Ti.

  16. Hydrogen Bonding between Sugar and Protein Is Responsible for Inhibition of Dehydration-Induced Protein Unfolding

    Microsoft Academic Search

    S. Dean Allison; Byeong Chang; Theodore W. Randolph; John F. Carpenter

    1999-01-01

    The nature of the interaction responsible for the inhibition of protein unfolding and subsequent damage by sugars during dehydration is unclear. The relationship between sample moisture content measured by coulometric Karl Fischer titration and the apparent moisture content predicted by the area of the protein side chain carboxylate band at approximately 1580 cm?1in infrared spectra of dried protein–sugar samples was

  17. Evaluation of Dehydrated Restaurant Food Waste Products as Feedstuffs for Finishing Pigs1,2

    Microsoft Academic Search

    R. O. Myer; J. H. Brendemuhl; D. D. Johnson

    Two dehydrated restaurant food waste (DFW) products were evaluated as potential feedstuffs for finishing pigs. For each product, fresh food wastes were obtained from food service operations at a resort complex in central Florida. The wastes were mostly leftover food and plate scrapings. The wastes were minced, blended with a feed stock (soy hulls and wheat flour (DFW1) or soy

  18. Removal of Sea Salt Hydrate Water from Seawater-Derived Samples by Dehydration

    E-print Network

    Russell, Lynn

    Removal of Sea Salt Hydrate Water from Seawater-Derived Samples by Dehydration Amanda A. Frossard of natural seawater contain both sea salts and organic components. Depending on the temperature, pressure, and speed of drying, the salt components can form hydrates that bind water, slowing evaporation of the water

  19. Dehydration Hardly Slows Hopping Toads (Rhinella granulosa) from Xeric and Mesic Environments

    E-print Network

    Angilletta, Michael

    451 Dehydration Hardly Slows Hopping Toads (Rhinella granulosa) from Xeric and Mesic Environments the effects of temperature and hydration on the hopping speeds of Rhinella granulosa, a small toad from interact to determine performance and whether toads from the Caatinga differ from their conspecifics from

  20. Multivariate analysis of the sensory changes in the dehydrated cowpea leaves.

    PubMed

    Nyambaka, Hudson; Ryley, Janice

    2004-09-01

    Processing of foods, especially dehydration is known to result in alteration of sensory and nutritional qualities. Cowpea leaves is one of the common leafy vegetables consumed in Kenya that contain high levels of pro-vitamin A compounds and has good carotene retention during processing. A tasting panel was trained using a quantitative descriptive analysis (QDA) test that was developed and used to characterize the sensory properties of dehydrated cowpea leaves. The panel identified sensory attributes in dehydrated cowpea leaves that were important in discriminating the dehydrated samples from the fresh material. Principal component analysis (PCA) was used to analyze the QDA scores. The first principal component (PC1) which accounted for 85% of the variance was an index of the interrelationship among variables in differentiating the samples while PC2, which accounted for the remaining variance measured the attributes influence in discriminating samples. The results of the sensory attributes mean scores showed that aroma, texture and appearance had high influence in discriminating between the fresh, the sun-dried and the solar-dried samples. The solar dried products were close to the fresh material, which was characterized, as soft and tender with an appealing dark green color, than the sun dried product. The sun dried products differed from the other products more on appearance. PMID:18969564

  1. Development and quality evaluation of dehydrated chicken meat rings using spent hen meat and different extenders.

    PubMed

    Mishra, Bidyut Prava; Chauhan, Geeta; Mendiratta, S K; Sharma, B D; Desai, B A; Rath, P K

    2015-04-01

    It is recommended that for effective utilization of spent hen meat, it should be converted into value added or shelf stable meat products. Since we are lacking in cold chain facilities, therefore there is imperative need to develop shelf stable meat products. The present study was envisaged with the objective to develop dehydrated chicken meat rings utilizing spent hen meat with different extenders. A basic formulation and processing conditions were standardized for dehydrated chicken meat rings. Extenders such as rice flour, barnyard millet flour and texturized soy granule powder at 5, 10 and 15 % levels were incorporated separately replacing the lean meat in pre standardized dehydrated chicken meat ring formulation. On the basis of physico-chemical properties and sensory scores optimum level of incorporation was adjudged as 10 %, 10 % and 5 % for rice flour, barnyard millet flour and texturized soy granule powder respectively. Products with optimum level of extenders were analysed for physico-chemical and sensory attributes. It was found that a good quality dehydrated chicken meat rings can be prepared by utilizing spent hen meat at 90 % level, potato starch 3 % and refined wheat flour 7 % along with spices, condiments, common salt and STPP. Addition of an optimum level of different extenders such as rice flour (10 %), barnyard millet flour (10 %) and TSGP (5 %) separately replacing lean meat in the formulation can give acceptable quality of the product. Rice flour was found to be the best among the three extenders studied as per the sensory evaluation. PMID:25829592

  2. Compositional heterogeneity reflects partial dehydration in three-dimensional crystals of bacteriorhodopsin.

    PubMed

    Schenkl, Selma; Portuondo, Erwin; Zgrablic, Goran; Chergui, Majed; Suske, Winfried; Dolder, Max; Landau, Ehud M; Haacke, Stefan

    2003-06-13

    Absorption, fluorescence and excitation spectra of three-dimensional bacteriorhodopsin crystals harvested from a lipidic cubic phase are presented. The combination of the spectroscopic experiments performed at room temperature, controlled pH and full external hydration reveals the presence of three distinct protein species. Besides the well-known form observed in purple membrane, we find two other species with a relative contribution of up to 30%. As the spectra are similar to those of dehydrated or deionized membranes containing bacteriorhodopsin, we suggest that amino acid residues, located in the vicinity of the retinal chromophore, have changed their protonation state. We propose partial dehydration during crystallization and/or room temperature conditions as the main source of this heterogeneity. This assignment is supported by an experiment showing interconversion of the species upon intentional dehydration and by crystallographic data, which have indicated an in-plane unit cell in 3D crystals comparable to that of dehydrated bacteriorhodopsin membranes. Full hydration of the proteins after the water-withdrawing crystallization process is hampered. We suggest that this hindered water diffusion originates mainly from a closure of hydrophobic crystal surfaces by lipid bilayers. The present spectroscopic work complements the crystallographic data, due to its ability to determine quantitatively compositional heterogeneity resulting from proteins in different protonation states. PMID:12787672

  3. Dehydration, rehydration and overhydration alter patterns of gene expression in the Antarctic midge, Belgica antarctica

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We investigated molecular responses elicited by three types of dehydration (fast, slow and cryoprotective), rehydration and overhydration in larvae of the Antarctic midge, Belgica antarctica. The larvae spend most the year encased in ice but during the austral summer are vulnerable to summer storms,...

  4. Air dehydration of strawberries: Effects of blanching and osmotic pretreatments on the kinetics of moisture transport

    Microsoft Academic Search

    C. A. Alvarez; R. Aguerre; R. Gómez; S. Vidales; S. M. Alzamora; L. N. Gerschenson

    1995-01-01

    The effect of blanching and glucose concentration before drying on the rate of moisture movement during the early stages of air dehydration of strawberries at 55 °C was studied. It was found that the effective diffusion coefficient of water in strawberries (Deff) was strongly affected by heat pretreatment, but glucose dipping after blanching caused no additional effect. Electron microscopic studies

  5. EARLY RESPONSIVE TO DEHYDRATION 15, a Negative Regulator of Abscisic Acid Responses in Arabidopsis1

    E-print Network

    Palva, Tapio

    EARLY RESPONSIVE TO DEHYDRATION 15, a Negative Regulator of Abscisic Acid Responses in Arabidopsis1 to the phytohormone abscisic acid (ABA). Overexpression of ERD15 reduced the ABA sensitivity of Arabidopsis manifested. The phytohormone abscisic acid (ABA) has a wide range of essential functions in plant growth and development

  6. Dehydration of the Upper Troposphere and Lower Stratosphere by Subvisible Cirrus Clouds Near the Tropical Tropopause

    NASA Technical Reports Server (NTRS)

    Jensen, Eric J.; Toon, Owen B.; Pfister, Leonhard; Selkirk, Henry B.

    1996-01-01

    The extreme dryness of the lower stratosphere is believed to be caused by freeze-drying of air as it enters the stratosphere through the cold tropical tropopause. Previous investigations have been focused on dehydration occurring at the tops of deep convective cloud systems, However, recent observations of a ubiquitous stratiform cirrus cloud layer near the tropical tropopause suggest the possibility of dehydration as air is slowly lifted by large-scale motions, In this study, we have evaluated this possibility using a detailed ice cloud model. Simulations of ice cloud formation in the temperature minima of gravity waves (wave periods of 1 - 2 hours) indicate that large numbers of ice crystals will likely form due to the low temperatures and rapid cooling. As a result, the crystals do not grow larger than about 10 microns, fallspeeds are no greater than a few cm/s, and little or no precipitation or dehydration occurs. However, ice cloud's formed by large-scale vertical motions (with lifetimes of a day or more) should have,fever crystals and more time for crystal sedimentation to occur, resulting in water vapor depletions as large as 1 ppmv near the tropopause. We suggest that gradual lifting near the tropical tropopause, accompanied by formation of thin cirrus, may account for the dehydration.

  7. Optimization of osmotic dehydration of papaya followed by air-drying

    Microsoft Academic Search

    Fabiano A. N. Fernandes; Sueli Rodrigues; Odisséia C. P. Gaspareto; Edson L. Oliveira

    2006-01-01

    Papayas are a fragile fruit; characteristic that limits large-scale exportation from the producing centers to countries in temperate regions. Loss of fruit ranges from 10% to 40% and could be reduced if papayas were dried. The process of osmotic dehydration followed by air-drying was studied and modeled for papaya preservation, so it could be optimized. The developed model has been

  8. Analysis of Chestnut Cellular Tissue during Osmotic Dehydration, Air Drying, and Rehydration Processes

    Microsoft Academic Search

    Ramón Moreira; Francisco Chenlo; Lívia Chaguri; Luis Mayor

    2010-01-01

    The analysis of changes in microstructure is very important in order to understand heat and mass transfer processes in biological systems and to evaluate physical properties and the quality of fresh and processed food materials. In this study, chestnut (Castanea sativa M.) samples were submitted to several processes such as osmotic dehydration by immersion in sucrose solution (60% w\\/w) at

  9. Treatment with lithium salts reduces ethanol dehydration shrinkage of glutaraldehyde fixed tissue

    Microsoft Academic Search

    A. Boyde; E. Maconnachie

    1980-01-01

    Changes in the area of glutaraldehyde fixed 15 day p.c. mouse embryo limbs were recorded using a Quantimet 720 image analysing computer attached to a light microscope: during a period of treatment with an isotonic salt solution (mostly halides of the alkali or alkaline earth metals); a subsequent wash with distilled water; and dehydration through a 30, 50, 70, 80,

  10. Volcanic fronts as a consequence of serpentinite dehydration in the fore-arc mantle wedge

    E-print Network

    Boyer, Edmond

    page -1- Volcanic fronts as a consequence of serpentinite dehydration in the fore-arc mantle wedge Villeurbanne, France Abstract Serpentinites exhumed from mantle wedges are enriched in elements that are mobile fore-arc mantle wedge from the subducting slab. Thus, serpentinites in the fore-arc mantle act

  11. Performance evaluation of microporous inorganic membranes in the dehydration of industrial solvents

    Microsoft Academic Search

    Stefan Sommer; Thomas Melin

    2005-01-01

    The separation potential of five different commercial tubular inorganic membranes consisting of A-, T- and Y-type zeolites from Mitsui and microporous silica from ECN and Pervatech has been examined in more than 30 dehydration applications. These separations include alcohols, glycols, carboxylic acids, esters, ethers, ketones, amines, nitriles, and halogenated hydrocarbons. The membranes combine excellent permeate flux with very good selectivity

  12. COMPARISON OF OSMOTIC REGULATION IN DEHYDRATION AND SALINITY-STRESSED SUNFLOWER SEEDLINGS

    Microsoft Academic Search

    Qingsong Zheng; Zhaopu Liu; Gang Chen; Yanzheng Gao; Qing Li; Jingyan Wang

    2010-01-01

    Plant dry matter accumulation rate (DMAR), relative water content (RWC), electrolyte leakage percentage (ELP), chlorophyll content, osmotic adjustment ability (OAA), and osmotica accumulation in leaves of sunflower (Helianthus annuus L.) seedlings under different levels of dehydration and salinity stress induced by iso-osmotic PEG (polyethylene glycol) or sodium chloride (NaCl) were evaluated. Plants were subjected to four stress treatments for 10

  13. Slab dehydration in the Earth's mantle transition zone Guillaume Richard , David Bercovici, Shun-Ichiro Karato

    E-print Network

    Slab dehydration in the Earth's mantle transition zone Guillaume Richard , David Bercovici, Shun water reservoir. The potentially high water content of the Earth's mantle transition zone is a key into the transition zone by developing a theoretical model of coupled thermal and chemical diffusion in a flat lying

  14. Overcoming recalcitrance in Porphyridium aerugineum Geitler employing encapsulation-dehydration cryopreservation methods.

    PubMed

    Amaral, R; Santos, M F; Santos, L M A

    2009-01-01

    Cultures of the recalcitrant microalga Porphyridium aerugineum were cryopreserved. A two-step, uncontrolled rapid freezing protocol, using methanol as cryoprotectant resulted in 23.8 percent viable cells. Cultures in the exponential growth phase, grown under low light intensity to prevent vacuole formation in cells, cryopreserved using a passive freezer, showed 22.4 percent viability. This value was enhanced to 31.5 percent when a controlled-rate freezer was employed. Optimized cultures in the exponential growth phase, cultivated in medium supplemented or not with vitamin B12, were then tested for freezing using the encapsulation-dehydration protocol. High cell loss was observed early during the sorbitol dehydration steps, but 63.6 percent of the remaining encapsulated cells were viable after thawing. This study confirmed the potential of encapsulation-dehydration as a method allowing to improve the low viability obtained with two-step freezing protocols. It also showed the importance of monitoring the response of algal cells to bead osmotic and evaporative dehydration pretreatments before freezing. PMID:20309503

  15. Hardening by Partial Dehydration and ABA Increase Desiccation Tolerance in the Cyanobacterial Lichen Peltigera polydactylon

    PubMed Central

    BECKETT, RICHARD P.; MAYABA, NOSISA; MINIBAYEVA, FARIDA V.; ALYABYEV, ALEXANDER J.

    2005-01-01

    • Background and Aims The ability of partial dehydration and abscisic acid pretreatments to increase desiccation tolerance in the cyanobacterial lichen Peltigera polydactylon was tested. • Methods Net photosynthesis and respiration were measured using infrared gas analysis during a drying and rehydration cycle. At the same time, the efficiency of photosystem two was measured using chlorophyll fluorescence, and the concentrations of chlorophyll a were spectrophotometrically assayed. Heat production was also measured during a shorter drying and rehydration cycle using differential dark microcalorimetry. • Key Results Pretreating lichens by dehydrating them to a relative water content of approx. 0·65 for 3?d, followed by storing thalli hydrated for 1?d in the light, significantly improved their ability to recover net photosynthesis during rehydration after desiccation for 15 but not 30?d. Abscisic acid pretreatment could substitute for partial dehydration. The improved rates of photosynthesis during the rehydration of pretreated material were not accompanied by preservation of photosystem two activity or chlorophyll a concentrations compared with untreated lichens. Partial dehydration and ABA pretreatments appeared to have little direct effect on the desiccation tolerance of the mycobiont, because the bursts of respiration and heat production that occurred during rehydration were similar in control and pretreated lichens. • Conclusions Results indicate that the photobiont of P. polydactylon possesses inducible tolerance mechanisms that reduce desiccation-induced damage to carbon fixation, and will therefore improve the supply of carbohydrates to the whole thallus following stress. In this lichen, ABA is involved in signal transduction pathways that increase tolerance of the photobiont. PMID:15857849

  16. Polymeric blend nanocomposite membranes for ethanol dehydration-effect of morphology and membrane-solvent interactions

    EPA Science Inventory

    Nanocomposite membranes (NCMs) of sodium alginate/poly(vinyl pyrrolidone) blend polymers incorporated with varying concentrations of phosphotungstic acid (H3PW12O40) (PWA) nanoparticles have been prepared and used in ethanol dehydration by the pervaporation (PV) technique. Effe...

  17. A Triple Iron Triathlon Leads to a Decrease in Total Body Mass but Not to Dehydration

    ERIC Educational Resources Information Center

    Knechtle, Beat; Knechtle, Patrizia; Rosemann, Thomas; Oliver, Senn

    2010-01-01

    A loss in total body mass during an ultraendurance performance is usually attributed to dehydration. We identified the changes in total body mass, fat mass, skeletal muscle mass, and selected markers of hydration status in 31 male nonprofessional ultratriathletes participating in a Triple Iron triathlon involving 11.4 km swimming, 540 km cycling…

  18. Improved Demulsifier Chemistry: A Novel Approach in the Dehydration of Crude Oil

    Microsoft Academic Search

    Friedrich Staiss; Roland Bohm; Rainer Kupfer

    1991-01-01

    With the ever-growing demand for more efficient dehydration and desalting of crude oil, classic demulsifiers no longer perform satisfactorily in most cases, and new chemical systems are required. This paper describes emulsion breakers, generally polyester amines, and gives detailed laboratory studies of their advantages over classic demulsifiers: more complete migration to the interface, improved emulsion breaking and coalescence, improved effluent

  19. Dehydration of aloe vera: simulation of drying curves and evaluation of functional properties

    Microsoft Academic Search

    S Simal; A Femen??a; P Llull; C Rosselló

    2000-01-01

    The effect of air-drying temperature (from 30°C to 80°C) on dehydration curves and functional properties (water retention capacity, WRC; swelling, SW; fat adsorption capacity, FAC) of aloe vera cubes has been investigated. A diffusional model taking into account sample shrinkage has been proposed and solved by using a finite difference method. The effective diffusivities estimated with the proposed model varied

  20. Water vapor transport and dehydration above convective outflow during Asian monsoon

    E-print Network

    Legras, Bernard

    Water vapor transport and dehydration above convective outflow during Asian monsoon R. James,1 M-scale transport and convection in determining the water vapor maximum at 100 hPa in the Asian monsoon region of overshoots. A good agreement between reconstructed water vapor and observations is obtained over Asia

  1. LOW-COST ZEOLITE MEMBRANE MODULES FOR SOLVENT DEHYDRATION - PHASE I

    EPA Science Inventory

    A number of very high-volume liquid chemicals form azeotropes with water and can be dehydrated to required purity levels only through the use of entrainers or drying agents. The handling and disposal of these additional chemicals present significant environmental risk...

  2. Mass transfer during osmotic dehydration of banana: Fickian diffusion in cylindrical configuration

    Microsoft Academic Search

    N. K. Rastogi; K. S. M. S. Raghavarao; K. Niranjan

    1997-01-01

    Mass transfer during osmotic dehydration of banana has been studied. The solution of Fick's law for unsteady state mass transfer in cylindrical configuration has been used to calculate the effective diffusion coefficients over a range of temperature (25–35 °C) and concentration (40–70 °B) of osmotic solution. The effective diffusion coefficient has been empirically correlated with the concentration and temperature of

  3. Energetic consequences of repeated and prolonged dehydration in the Antarctic midge, Belgica antarctica

    E-print Network

    Lee Jr., Richard E.

    antarctica Nicholas M. Teets a, , Yuta Kawarasaki b , Richard E. Lee Jr. b , David L. Denlinger a of the Antarctic midge, Belgica antarctica, routinely face periods of limited water availability in their natural environments on the Antarctic Peninsula. As a result, B. antarctica is one of the most dehydration

  4. FEASIBILITY OF USING INFRARED HEATING FOR BLANCHING AND DEHYDRATION OF FRUITS AND VEGETABLES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to evaluate the feasibility of using medium and far infrared heating for blanching and dehydration of various fruits and vegetables. The infrared blanching was referred as infrared dry-blanching (IDB) in this study since no water or steam was used. A catalytic infra...

  5. On the use of edible coatings to monitor osmotic dehydration kinetics for minimal solids uptake

    Microsoft Academic Search

    Malgorzata Matuska; Andrzej Lenart; Harris N. Lazarides

    2006-01-01

    During osmotic dehydration, extensive solute (i.e. sugar) uptake is an undesirable side effect, as it is counteracting water removal, while it modifies nutritional and\\/or organoleptic properties in a rather negative mode, damaging the natural, fresh product profile. Coating of whole strawberries with selected edible (polysaccharide) films before osmotic processing was found to favor water removal and prevent solute uptake. Among

  6. MODELLING OF OSMOTIC DEHYDRATION OF SWEET POTATO (IPOMOEA BATATAS): DETERMINATION OF MASS EFFECTIVE DIFFUSIVITY COEFFICIENTS

    Microsoft Academic Search

    G. C. Antonio; P. M. Azoubel; M. R. Simões

    Osmotic dehydration is a process that enables partial removal of water by direct contact of a product with a hypertonic medium. This prompts two major simultaneously countercurrent flows: water flow from the product to the surrounding solution and solutes flow into the product. Leakage of the product solutes (sugars, organic acids, mineral, etc.) is quantitatively negligible, but may be important

  7. Identification of a novel dehydration responsive gene, drp10, from the African clawed frog, Xenopus laevis.

    PubMed

    Biggar, Kyle K; Biggar, Yulia; Storey, Kenneth B

    2015-06-01

    During periods of environmental stress a number of different anuran species employ adaptive strategies to promote survival. Our study found that in response to dehydration (i.e., loss of total body water content), the African clawed frog (Xenopus laevis) increased the expression of a novel gene (drp10) that encodes a structural homolog of the freeze-responsive FR10 protein found in wood frogs. Similar to FR10, the DRP10 protein was found to also contain a highly conserved N-terminal cleavable signal peptide. Furthermore, DRP10 was found to have high structural homology to the available crystal structures of type A and E apolipoproteins in Homo sapiens, and a type IV LS-12 anti-freeze protein in the longhorn sculpin, Myoxocephalus octodecemspinosis. In response to dehydration, the transcript expression of drp10 was found to increase 1.52?±?0.16-fold and 1.97?±?0.11-fold in response to medium (15%) and high (30%) dehydration stresses in the liver tissue of X. laevis, respectively, while drp10 expression increased 2.12?±?0.12-fold and 1.46?±?0.16-fold in kidney tissue. Although the molecular function of both dehydration-responsive DRP10 and the freeze-responsive FR10 have just begun to be elucidated, it is likely that both are frog-specific proteins that likely share a similar purpose during water-related stresses. J. Exp. Zool. 323A: 375-381, 2015. © 2015 Wiley Periodicals, Inc. PMID:25866033

  8. Sec-Mediated Transport of Posttranslationally Dehydrated Peptides in Lactococcus lactis? †

    PubMed Central

    Kuipers, Anneke; Wierenga, Jenny; Rink, Rick; Kluskens, Leon D.; Driessen, Arnold J. M.; Kuipers, Oscar P.; Moll, Gert N.

    2006-01-01

    Nisin is a lanthionine-containing antimicrobial peptide produced by Lactococcus lactis. Its (methyl)lanthionines are introduced by two posttranslational enzymatic steps involving the dehydratase NisB, which dehydrates serine and threonine residues, and the cyclase NisC, which couples these dehydrated residues to cysteines, yielding thioether-bridged amino acids called lanthionines. The prenisin is subsequently exported by the ABC transporter NisT and extracellularly processed by the peptidase NisP. L. lactis expressing the nisBTC genes can modify and secrete a wide range of nonlantibiotic peptides. Here we demonstrate that in the absence of NisT and NisC, the Sec pathway of L. lactis can be exploited for the secretion of dehydrated variants of therapeutic peptides. Furthermore, posttranslational modifications by NisB and NisC still occur even when the nisin leader is preceded by a Sec signal peptide or a Tat signal peptide 27 or 44 amino acids long, respectively. However, transport of fully modified prenisin via the Sec pathway is impaired. The extent of NisB-mediated dehydration could be improved by raising the intracellular concentration NisB or by modulating the export efficiency through altering the signal sequence. These data demonstrate that besides the traditional lantibiotic transporter NisT, the Sec pathway with an established broad substrate range can be utilized for the improved export of lantibiotic enzyme-modified (poly)peptides. PMID:17041158

  9. Surviving the cold: molecular analyses of insect cryoprotective dehydration in the Arctic springtail Megaphorura arctica (Tullberg)

    Microsoft Academic Search

    Melody S Clark; Michael AS Thorne; Jelena Pura?; Gavin Burns; Guy Hillyard; Željko D Popovi?; Gordana Grubor-Lajši?; M Roger Worland

    2009-01-01

    BACKGROUND: Insects provide tractable models for enhancing our understanding of the physiological and cellular processes that enable survival at extreme low temperatures. They possess three main strategies to survive the cold: freeze tolerance, freeze avoidance or cryoprotective dehydration, of which the latter method is exploited by our model species, the Arctic springtail Megaphorura arctica, formerly Onychiurus arcticus (Tullberg 1876). The

  10. Subquality natural gas sweetening and dehydration potential of the physical solvent N-formyl-morpholine

    Microsoft Academic Search

    J. T. Semrau; N. Palla; A. L. Lee

    1995-01-01

    Almost all gas produced in the United States requires processing before it is placed in the transmission system. For approximately 50% of the gas, this is just dehydration. The remainder, however, requires processing that is more complex and costly. A report to the Gas Research Institute states that about 30% of the proven gas reserves contained sufficient nitrogen, carbon dioxide

  11. Combined impacts of irradiance and dehydration on leaf hydraulic conductance: insights into vulnerability and

    E-print Network

    Sack, Lawren

    , and similar dehydration responses would arise from the control of stomata by Yleaf or a corre- lated signal stomata open for photosynthesis, water is lost via transpiration, and Kleaf needs to remain high sheath and mesophyll tissue before evaporating through the stomata.The decline of Kleaf with Yleaf may

  12. Reactions of cresol in hot aqueous borate solutions

    SciTech Connect

    Tsao, L. [Lawrence Berkeley Lab., CA (United States); Weres, O. [Sonoma Research Co., Vineburg, CA (United States)

    1992-04-01

    Phenol and methylphenol (cresol) are constituents of certain waste streams being considered for underground injection. We studied reactions of these compounds in solutions with other constituents of the waste streams and suspended clay at concentrations and temperatures higher than expected in natural situations, i.e. at 200{degrees}C and 250{degrees}C. Under these conditions, the predominant reaction was the demethylation of cresol to form phenol. This reaction was catalyzed strongly by clay. We were able to quantify phenol production. Other important reactions were a variety of condensation reactions in which two cresol molecules fuse. We found evidence of the intermolecular migration of methyl groups from the molecular weights of some of these condensation reactions. By digesting a sample of reacted clay with hydrofluoric acid we determined that under these conditions phenol and cresol did not bind appreciably to clay but that the condensation products did.

  13. Antikaon condensation in neutron stars

    E-print Network

    Subrata Pal; Debades Bandyopadhyay; Walter Greiner

    2000-03-08

    We investigate the condensation of charged $K^-$ meson and neutral $\\bar K^0$ meson in dense neutron star matter. Calculations are performed in relativistic mean field models in which both the baryon-baryon and (anti)kaon-baryon interactions are mediated by meson exchange. It is found that $\\bar K^0$ condensation is quite sensitive to the antikaon optical potential and depends more strongly on the nucleonic equation of state. For moderate values of antikaon potential and a rather stiff equation of state, a significant region of maximum mass star will contain $\\bar K^0$ meson. The critical density of $\\bar K^0$ condensation is always higher than that of $K^-$ condensation. With the appearance of $K^-$ and $\\bar K^0$ condensates, pairs of $p-K^-$ and $n-\\bar K^0$ are produced with equal proportion leading to a perfectly symmetric matter of nucleons and antikaons in neutron stars. Along with $K^-$ condensate, $\\bar K^0$ condensate makes the equation of state much softer resulting in smaller maximum mass stars compared to the case without any condensate.

  14. Condensed Matter Physics - Biology Resonance

    Microsoft Academic Search

    G. Baskaran

    2000-01-01

    The field of condensed matter physics had its genesis this century and it has had a remarkable evolution. A closer look at its growth reveals a hidden aim in the collective consciousness of the field - a part of the development this century is a kind of warm up exercise to understand the nature of living condensed matter, namely the

  15. Principles of Condensed Matter Physics

    Microsoft Academic Search

    P. M. Chaikin; T. C. Lubensky

    2000-01-01

    Now in paperback, this book provides an overview of the physics of condensed matter systems. Assuming a familiarity with the basics of quantum mechanics and statistical mechanics, the book establishes a general framework for describing condensed phases of matter based on symmetries and conservation laws. After surveying the structure and properties of materials with different symmetries, it explores the role

  16. Cavitation in dehydrating xylem of Picea abies: energy properties of ultrasonic emissions reflect tracheid dimensions.

    PubMed

    Mayr, Stefan; Rosner, Sabine

    2011-01-01

    Ultrasonic emission (UE) testing is used to analyse the vulnerability of xylem to embolism, but the number of UEs often does not sufficiently reflect effects on hydraulic conductivity. We monitored the absolute energy of UE signals in dehydrating xylem samples hypothesizing that (i) conduit diameter is correlated with UE energy and (ii) monitoring of UE energy may enhance the utility of this technique for analysis of xylem vulnerability. Split xylem samples were prepared from trunk wood of Picea abies, and four categories of samples, derived from mature (I: earlywood, II: 30-50% latewood, III: >50% latewood) or juvenile wood (IV: earlywood) were used. Ultrasonic emissions during dehydration were registered and anatomical parameters (tracheid lumen area, number per area) were analysed from cross-sections. Attenuation of UE energy was measured on a dehydrating wood beam by repeated lead breaks. Vulnerability to drought-induced embolism was analysed on dehydrating branches by hydraulic, UE number or UE energy measurements. In split samples, the cumulative number of UEs increased linearly with the number of tracheids per cross-section, and UE energy was positively correlated with the mean lumen area. Ultrasonic emission energies of earlywood samples (I and IV), which showed normally distributed tracheid lumen areas, increased during dehydration, whereas samples with latewood (II and III) exhibited a right-skewed distribution of lumina and UE energies. Ultrasonic emission energy was hardly influenced by moisture content until ?40% moisture loss, and decreased exponentially thereafter. Dehydrating branches showed a 50% loss of conductivity at -3.6 MPa in hydraulic measurements and at -3.9 and -3.5 MPa in UE analysis based on cumulative number or energy of signals, respectively. Ultrasonic emission energy emitted by cavitating conduits is determined by the xylem water potential and by the size of element. Energy patterns during dehydration are thus influenced by the vulnerability to cavitation, conduit size distribution as well as attenuation properties. Measurements of UE energy may be used as an alternative to the number of UEs in vulnerability analysis. PMID:21389002

  17. Dehydration stress memory genes of Zea mays; comparison with Arabidopsis thaliana

    PubMed Central

    2014-01-01

    Background Pre-exposing plants to diverse abiotic stresses may alter their physiological and transcriptional responses to a subsequent stress, suggesting a form of “stress memory”. Arabidopsis thaliana plants that have experienced multiple exposures to dehydration stress display transcriptional behavior suggesting “memory” from an earlier stress. Genes that respond to a first stress by up-regulating or down-regulating their transcription but in a subsequent stress provide a significantly different response define the ‘memory genes’ category. Genes responding similarly to each stress form the ‘non-memory’ category. It is unknown whether such memory responses exists in other Angiosperm lineages and whether memory is an evolutionarily conserved response to repeated dehydration stresses. Results Here, we determine the transcriptional responses of maize (Zea mays L.) plants that have experienced repeated exposures to dehydration stress in comparison with plants encountering the stress for the first time. Four distinct transcription memory response patterns similar to those displayed by A. thaliana were revealed. The most important contribution is the evidence that monocot and eudicot plants, two lineages that have diverged 140 to 200 M years ago, display similar abilities to ‘remember’ a dehydration stress and to modify their transcriptional responses, accordingly. The highly sensitive RNA-Seq analyses allowed to identify genes that function similarly in the two lineages, as well as genes that function in species-specific ways. Memory transcription patterns indicate that the transcriptional behavior of responding genes under repeated stresses is different from the behavior during an initial dehydration stress, suggesting that stress memory is a complex phenotype resulting from coordinated responses of multiple signaling pathways. Conclusions Structurally related genes displaying the same memory responses in the two species would suggest conservation of the genes’ memory during the evolution of plants’ dehydration stress response systems. On the other hand, divergent transcription memory responses by genes encoding similar functions would suggest occurrence of species-specific memory responses. The results provide novel insights into our current knowledge of how plants respond to multiple dehydration stresses, as compared to a single exposure, and may serve as a reference platform to study the functions of memory genes in adaptive responses to water deficit in monocot and eudicot plants. PMID:24885787

  18. Four distinct types of dehydration stress memory genes in Arabidopsis thaliana

    PubMed Central

    2013-01-01

    Background How plants respond to dehydration stress has been extensively researched. However, how plants respond to multiple consecutive stresses is virtually unknown. Pre-exposure to various abiotic stresses (including dehydration) may alter plants’ subsequent responses by improving resistance to future exposures. These observations have led to the concept of ‘stress memory’ implying that during subsequent exposures plants provide responses that are different from those during their first encounter with the stress. Genes that provide altered responses in a subsequent stress define the ‘memory genes’ category; genes responding similarly to each stress form the ‘non-memory’ category. Results Using a genome-wide RNA-Seq approach we determine the transcriptional responses of Arabidopsis plants that have experienced multiple exposures to dehydration stress and compare them with the transcriptional behavior of plants encountering the stress for the first time. The major contribution of this study is the revealed existence of four distinct, previously unknown, transcription memory response patterns of dehydration stress genes in A.thaliana. The biological relevance for each of the four memory types is considered in the context of four overlapping strategies employed by a plant to improve its stress tolerance and/or survival: 1) increased synthesis of protective, damage-repairing, and detoxifying functions; 2) coordinating photosynthesis and growth under repetitive stress; 3) re-adjusting osmotic and ionic equilibrium to maintain homeostasis; and 4) re-adjusting interactions between dehydration and other stress/hormone regulated pathways. Conclusions The results reveal the unknown, hitherto, existence of four distinct transcription memory response types in a plant and provide genome-wide characterization of memory and non-memory dehydration stress response genes in A.thaliana. The transcriptional responses during repeated exposures to stress are different from known responses occurring during a single exposure. GO analyses of encoded proteins suggested implications for the cellular/organismal protective, adaptive, and survival functions encoded by the memory genes. The results add a new dimension to our understanding of plants’ responses to dehydration stress and to current models for interactions between different signaling systems when adjusting to repeated spells of water deficits. PMID:24377444

  19. Early Events in Skin Appendage Formation: Induction of Epithelial Placodes and Condensation of Dermal Mesenchyme

    E-print Network

    Chuong, Cheng-Ming

    . During the inductive stage, cells interact in a fashion best described by a reaction-diffusion mechanism of skin appendage formation: induction. Key words: adhesion molecules/BMP/embryonic induction/feather/FGF/hair/mesenchymal condensation/ reaction diffusion/SHH/b-catenin. Journal of Investigative Dermatology Symposium Proceedings 4

  20. Acetaldehyde Aldol Condensation Kinetics J. 8. ANDERSON' and M. S. PETERS

    E-print Network

    Anderson, James B.

    Acetaldehyde Aldol Condensation Kinetics J. 8. ANDERSON' and M. S. PETERS University of Illinois, Urbana, 111. ACETALDEHYDEmay react to form aldol when- ever acetaldehyde and hydroxide ions are present reactions such as the formation of pentaerythrose. The mechanism of the acetaldehyde aldol reaction has been

  1. Photochemical activity of Titan's low-altitude condensed haze.

    PubMed

    Gudipati, Murthy S; Jacovi, Ronen; Couturier-Tamburelli, Isabelle; Lignell, Antti; Allen, Mark

    2013-01-01

    Titan, the largest moon of Saturn and similar to Earth in many aspects, has unique orange-yellow colour that comes from its atmospheric haze, whose formation and dynamics are far from well understood. Present models assume that Titan's tholin-like haze formation occurs high in atmosphere through gas-phase chemical reactions initiated by high-energy solar radiation. Here we address an important question: Is the lower atmosphere of Titan photochemically active or inert? We demonstrate that indeed tholin-like haze formation could occur on condensed aerosols throughout the atmospheric column of Titan. Detected in Titan's atmosphere, dicyanoacetylene (C?N?) is used in our laboratory simulations as a model system for other larger unsaturated condensing compounds. We show that C4N2 ices undergo condensed-phase photopolymerization (tholin formation) at wavelengths as long as 355 nm pertinent to solar radiation reaching a large portion of Titan's atmosphere, almost close to the surface. PMID:23552063

  2. Leaf Shrinkage with Dehydration: Coordination with Hydraulic Vulnerability and Drought Tolerance1[C][W][OPEN

    PubMed Central

    Scoffoni, Christine; Vuong, Christine; Diep, Steven; Cochard, Hervé; Sack, Lawren

    2014-01-01

    Leaf shrinkage with dehydration has attracted attention for over 100 years, especially as it becomes visibly extreme during drought. However, little has been known of its correlation with physiology. Computer simulations of the leaf hydraulic system showed that a reduction of hydraulic conductance of the mesophyll pathways outside the xylem would cause a strong decline of leaf hydraulic conductance (Kleaf). For 14 diverse species, we tested the hypothesis that shrinkage during dehydration (i.e. in whole leaf, cell and airspace thickness, and leaf area) is associated with reduction in Kleaf at declining leaf water potential (?leaf). We tested hypotheses for the linkage of leaf shrinkage with structural and physiological water relations parameters, including modulus of elasticity, osmotic pressure at full turgor, turgor loss point (TLP), and cuticular conductance. Species originating from moist habitats showed substantial shrinkage during dehydration before reaching TLP, in contrast with species originating from dry habitats. Across species, the decline of Kleaf with mild dehydration (i.e. the initial slope of the Kleaf versus ?leaf curve) correlated with the decline of leaf thickness (the slope of the leaf thickness versus ?leaf curve), as expected based on predictions from computer simulations. Leaf thickness shrinkage before TLP correlated across species with lower modulus of elasticity and with less negative osmotic pressure at full turgor, as did leaf area shrinkage between full turgor and oven desiccation. These findings point to a role for leaf shrinkage in hydraulic decline during mild dehydration, with potential impacts on drought adaptation for cells and leaves, influencing plant ecological distributions. PMID:24306532

  3. Dehydration and vernalization treatments identify overlapping molecular networks impacting endodormancy maintenance in leafy spurge crown buds.

    PubMed

    Do?ramac?, Münevver; Horvath, David P; Christoffers, Michael J; Anderson, James V

    2011-12-01

    Leafy spurge (Euphorbia esula L.) is a herbaceous perennial weed that reproduces vegetatively from an abundance of underground adventitious buds (UABs), which undergo well-defined phases of seasonal dormancy (para-, endo-, and ecodormancy). In this study, the effects of dehydration stress on vegetative growth and flowering potential from endodormant UABs of leafy spurge was monitored. Further, microarray analysis was used to identify critical signaling pathways of transcriptome profiles associated with endodormancy maintenance in UABs. Surprisingly, only 3-day of dehydration stress is required to break the endodormant phase in UABs; however, the dehydration-stress treatment did not induce flowering. Previous studies have shown that prolonged cold treatment of UABs breaks endodormancy and induces a vernalization response leading to flowering. Thus, in this study, comparing transcriptome data from UABs exposed to short-term dehydration and vernalization provided a unique approach to identify overlapping molecular mechanisms involved in endodormancy maintenance and floral competence. Analysis of transcriptome data associated with breaking endodormancy by both environmental treatments identified LEC1, PHOTOSYSTEM I RC, and brassinosteroids as common central hubs of upregulated genes, while DREB1A, CBF2, GPA1, MYC2, bHLH, BZIP, and flavonoids were identified as common central hubs of downregulated genes. The majority of over-represented gene sets common to breaking endodormancy by dehydration stress and vernalization were downregulated and included pathways involved in hormone signaling, chromatin modification, and circadian rhythm. Additionally, the over-represented gene sets highlighted pathways involved in starch and sugar degradation and biogenesis of carbon skeletons, suggesting a high metabolic activity is necessary during the endodormant phase. The data presented in this study helped to refine our previous model for dormancy regulation. PMID:21789635

  4. Cryopreservation of embryogenic cell suspensions by encapsulation-vitrification and encapsulation-dehydration.

    PubMed

    Yin, Zhenfang; Chen, Long; Zhao, Bing; Zhu, Yongxing; Wang, Qiaochun

    2012-01-01

    Encapsulation-vitrification and encapsulation-dehydration are two newly developed techniques for cryopreservation of embryogenic cell suspensions. Here, we describe the two protocols using grapevine (Vitis) as a model plant. Cell suspensions at the exponential growth stage cultured in a cell suspension maintenance medium are encapsulated to form beads, each being about 4 mm in diameter and containing 25% cells. In the encapsulation-vitrification procedure, the beads are stepwise precultured in increasing concentrations of sucrose medium up to 0.75 M, with 1 day for each concentration. The precultured beads are treated with a loading solution for 60 min and then dehydrated with plant vitrification solution 2 at 0°C for 270 min before a direct immersion in liquid nitrogen. Following cryostorage, the beads are rapidly rewarmed at 40°C for 3 min and then unloaded with 1 M sucrose solution for 30 min. In the encapsulation-dehydration procedure, the beads are precultured in increasing concentrations of sucrose medium up to 1 M, with 1 day for each concentration, and then maintained on 1 M sucrose medium for 3 days. The precultured beads are dehydrated for 6 h under a sterile air flow, prior to rapid freezing in liquid nitrogen. The freezing and rewarming procedures are the same as used in the encapsulation-vitrification technique. The unloaded beads from encapsulation-vitrification and rewarmed beads from encapsulation-dehydration are postcultured on a recovery medium for 3 days at 25°C in the dark for survival. Surviving cells are transferred to a regrowth medium to induce cell proliferation. Embryogenic cell suspensions are reestablished by suspending the cells in a cell suspension maintenance medium maintained on a gyratory shaker at 25°C in the dark. For plant regeneration, surviving cells are transferred from the recovery medium to an embryo maturation medium and maintained at 25°C under light conditions. Embryos at the torpedo stage are cultured on a rooting medium until whole plantlet regenerates. PMID:22610621

  5. Real-Time Observation of a Non-Equilibrium Liquid Condensate Confined at Tensile Crack Tips in Oxide Glasses

    E-print Network

    Demouchy, Sylvie

    Real-Time Observation of a Non-Equilibrium Liquid Condensate Confined at Tensile Crack Tips. Condensate formation and changes in the extent and the shape are demonstrated for a wide range of macroscopic at the crack tip.3 Water is known to be the crucial reactant in this reaction.4,5 More recently, Davis

  6. Condensation on Superhydrophobic Copper Oxide Nanostructures

    E-print Network

    Enright, Ryan

    Condensation is an important process in both emerging and traditional power generation and water desalination technologies. Superhydrophobic nanostructures promise enhanced condensation heat transfer by reducing the ...

  7. Condensation on superhydrophobic copper oxide nanostructures

    E-print Network

    Dou, Nicholas (Nicholas Gang)

    2012-01-01

    Condensation is an important process in many power generation and water desalination technologies. Superhydrophobic nanostructured surfaces have unique condensation properties that may enhance heat transfer through a ...

  8. Faculty Position Experimental Condensed Matter Physics

    E-print Network

    Hone, James

    Faculty Position Experimental Condensed Matter Physics Columbia University The Columbia University Department of Physics seeks to appoint an assistant professor in experimental condensed matter physics

  9. A- to B-Type Olivine Fabric Transitions Associated with Hydration, Dehydration and Shear Above the Farallon Flat Slab

    NASA Astrophysics Data System (ADS)

    Behr, W. M.; Smith, D.

    2014-12-01

    We investigate mantle rocks associated with hydration, dehydration and shear above the Farallon flat-slab at its contact with the base of North America. The rocks we focus on are ultramafic inclusions hosted within serpentinized ultramafic microbreccia diatremes of the Navajo Volcanic Field (New Mexico) that erupted to the surface at the waning stages of the Laramide orogeny. A large number of petrological and geochronological studies have pinpointed the origin of these rocks to the hydrated mantle wedge above the Farallon slab as well as tectonically eroded and entrained fragments of the plate interface. We combine petrological observations and EBSD measurements of olivine grainsize and LPO to examine the effects of hydration on olivine fabric development in different parts of the supra-subduction zone mantle. The rocks examined include weakly deformed to strongly foliated tectonites we interpret to represent partially hydrated fragments of the upper plate mantle; and mylonites and ultramylonites we interpret to represent deformed fragments of the plate interface. The rocks deformed at temperatures ranging from 500-900°C based on thermometry, and olivine compositions in some record heating just before incorporation in the diatreme mix. We observe the following: Tectonites exhibit A-type bulk olivine LPOs, but show transitions to B-type LPO in local, fine-grained, dynamically recrystallized regions associated with hydrous minerals. Mylonites and ultramylonites with stable chlorite and/or antigorite and recrystallized grainsizes of less than 10?m show strong B-type olivine LPOs. A single mylonite with recrystallized grainsizes of ~35?m shows evidence for prograde metamorphism and dehydration through the chlorite breakdown reaction at temperatures above ~770°C. It contains no hydrous minerals and shows a strong A-type olivine LPO. Together these rocks demonstrate a strong correlation between hydration under high stress conditions, and B-type olivine LPO, consistent with experimental studies that indicate this fabric forms at high water contents and high stress. If interpreted in terms of supra-subduction zone seismic anisotropy, these rocks are consistent with a transition from trench-parallel fast directions close to the trench to trench-perpendicular fast directions away from the trench.

  10. Characterization of spacecraft humidity condensate

    NASA Technical Reports Server (NTRS)

    Muckle, Susan; Schultz, John R.; Sauer, Richard L.

    1994-01-01

    When construction of Space Station Freedom reaches the Permanent Manned Capability (PMC) stage, the Water Recovery and Management Subsystem will be fully operational such that (distilled) urine, spent hygiene water, and humidity condensate will be reclaimed to provide water of potable quality. The reclamation technologies currently baselined to process these waste waters include adsorption, ion exchange, catalytic oxidation, and disinfection. To ensure that the baseline technologies will be able to effectively remove those compounds presenting a health risk to the crew, the National Research Council has recommended that additional information be gathered on specific contaminants in waste waters representative of those to be encountered on the Space Station. With the application of new analytical methods and the analysis of waste water samples more representative of the Space Station environment, advances in the identification of the specific contaminants continue to be made. Efforts by the Water and Food Analytical Laboratory at JSC were successful in enlarging the database of contaminants in humidity condensate. These efforts have not only included the chemical characterization of condensate generated during ground-based studies, but most significantly the characterization of cabin and Spacelab condensate generated during Shuttle missions. The analytical results presented in this paper will be used to show how the composition of condensate varies amongst enclosed environments and thus the importance of collecting condensate from an environment close to that of the proposed Space Station. Although advances were made in the characterization of space condensate, complete characterization, particularly of the organics, requires further development of analytical methods.

  11. Current issues in sol-gel reaction kinetics

    SciTech Connect

    Assink, R.A.; Kay, B.D.

    1990-01-01

    This paper surveys a few of the current issues in sol-gel reaction kinetics. Many times seemingly modest changes in reactants or reaction conditions can lead to substantial differences in the overall reaction rates and pathways. For example, qualitative features of the reaction kinetics can depend on catalyst concentration. At very high acid-catalyst concentrations, reverse are significant for TMOS sol-gels, while for moderate acid-catalyst concentrations, reverse reactions are substantially reduced. The reaction kinetics are substantially reduced. The reaction kinetics of two similar tetraalkoxysilanes: tetramethoxysilane (TMOS) and tetraethoxysilane (TEOS), can be markedly different under identical reaction conditions. Under acid-catalyzed reaction conditions, a TMOS sol-gel undergoes both water-and alcohol-producing condensation reactions while a TEOS sol-gel undergoes only water-producing condensation. The early time hydrolysis and condensation reactions of a TMOS sol-gel are statistical in nature and can be quantitatively described by a few simple reaction rate constants while the reaction behavior of a TEOS sol-gel is markedly nonstatistical. A comprehensive theory of sol-gel kinetics must address diverse experimental findings. 9 refs., 3 figs., 1 tab.

  12. Electrohydrodynamically enhanced condensation heat transfer 

    E-print Network

    Wawzyniak, Markus

    1993-01-01

    . The occurrence of a corona discharge led to the appearance of a wavy motion on the condensate film. As the voltage was increased, rivulets of Freon were observed running down the plate and finally, at an even higher voltage, condensate was blown away f... of the Plexiglas container, (b) view of cooled plate with corona wire. [Velkoff and Miller, 1965] . . . . Fig. 1. 4 Effect of electric field on condensation. 5 mesh screen grid parallel to plate. [Velkoff and Miller, 1965]. Fig. 1. 5 Variation of h (mean heat...

  13. Kinetics of formation of monodisperse colloidal silica particles through the hydrolysis and condensation of tetraethyorthosilicate

    SciTech Connect

    Chen, S.L. [Univ. of Petroleum, Dongying, Shandong (China). Dept. of Chemical Engineering] [Univ. of Petroleum, Dongying, Shandong (China). Dept. of Chemical Engineering; Dong, P.; Yang, G.H.; Yang, J.J. [Univ. of Petroleum, Changping, Beijing (China). National Lab. of Heavy Oil Research] [Univ. of Petroleum, Changping, Beijing (China). National Lab. of Heavy Oil Research

    1996-12-01

    Kinetic studies of the hydrolysis and condensation of tetraethyl orthosilicate (TEOS) during the formation of uniform silica particles were performed through determining concentrations of TEOS and silicic acid by means of gas chromatography and a conductometer, respectively. It was shown that both hydrolysis of TEOS and condensation of Si(OH){sub 4} are first order with TEOS and Si(OH){sub 4}, respectively, and the relationships of the hydrolysis and condensation rate constants with reaction condition variables, such as temperature, NH{sub 3} concentration, and H{sub 2}O concentration, were determined. in addition, the particle growth rate was investigated with relation to the hydrolysis and condensation kinetics. Experiments showed that, during most of the reaction, the amount of formed particles is less than that of consumed TEOS, indicating that reaction intermediates exist during the process of silica formation. In the early stages of the Stoeber process, the reaction intermediates include silicic acid and subparticles, while in the case of seed growth experiments without the formation of new particles or after the early stages of Stoeber process, the reaction intermediates primarily consist of silicic acid and the growth rate of silica equals the rate of silicic acid condensation.

  14. [The role of cortical microtubules in moss protonemal cells during dehydration/rehydration cycle].

    PubMed

    Chen, Zhi-Ling; Ouyang, Hao-Miao; Liu, Xiang-Lin; Xia, Gui-Xian

    2003-05-01

    Plant cells response to water deficit through a variety of physiological processes. In this work, we studied the function of microtubule cytoskeleton during dehydration/rehydration cycle in moss (Atrichum undulatum) protonemal cells as a model system. The morphological and cytological change of protonemal cells during dehydration and rehydration cycle were first investigated. Under normal conditions, protonemal cells showed bright green colour and appeared wet and fresh. Numerous chloroplasts distributed regularly throughout the cytoplasm in each cell. After dehydration treatment, protonemal cells lost most of their chlorophylls and turned to look yellow and dry. In addition, dehydration caused plasmolysis in these cells. Upon rehydration, the cells could recover completely from the dehydrated state. These results indicated that moss had a remarkable intrinsic ability to survive from the extreme drought stress. Microtubule, an important component of cytoskeleton, is considered to play crucial roles in the responses to some environmental stresses such as cold and light. To see if it is also involved in the drought tolerance, dynamic organization of microtubules in protonemal cells of Atrichum undulatum subjected to drought and rehydration were examined by indirect immunofluorescence combined with confocal lasersharp scanning microscopy. The cortical microtubules were arranged into a fine structure with a predominant orientation parallel to the long axis of the cells in the control cells. After dehydration, the microtubule organization was remarkablly altered and the fine microtubule structure disappeared whereas some thicker cables formed. When the cells were grown under rehydration conditions, the fine microtubule arrays reappeared. These results provided a piece of evidence that microtubules play a role in the cellular responses to drought stress in moss. Furthermore, we analyzed the effects of the microtubule-disrupting agent colchicine on the morphology recovery of the protonemal cells during rehydration process. The cells were incubated with colchicine, followed by drought stress treatment and rehydration in the presence of colchicine to prevent recovery of microtubule organization. Results from immunofluorescence showed that microtubule arrays were broken down into smaller fragments. Compared to the cells treated with drought stress alone, the cells treated with drought stress in the presence of colchicine could not recover after rehydration treatment. The morphology resembled those of the drought treated cells, with obvious plasmolysis phenomena and loss of chlorophyll content. These results support the notion that microtubules were involved in the deccication tolerance mechanism in Atrichum undulatum. PMID:15969014

  15. Selective condensation of aminoacyl adenylates by nucleoproteinoid microparticles.

    NASA Technical Reports Server (NTRS)

    Nakashima, T.; Fox, S. W.

    1972-01-01

    Microparticles composed of each of four enzymically synthesized homopolynucleotides and the same lysine-rich proteinoid have been found to influence the condensation of the AMP-anhydrides of each of four amino acids. The conditions of preparation of the particles and other variables of the experiments control the types of reaction. When a period set of conditions was identified empirically, the incorporation favored the amino acids whose present-day codons are related to the homopolynucleotide in the particle.

  16. Photodissociation of condensed carbon dioxide below the gas phase thresholds

    Microsoft Academic Search

    J. M. Coquel; L. Siller; J. Wilkes; R. Carrapa; C. L. A. Lamont; T. Almeida Gasche; R. E. Palmer; A. M. C. Moutinho

    1998-01-01

    We have investigated photodesorption from condensed carbon dioxide for photon energies ranging from 13 to 35 eV using synchrotron radiation. We report the desorption of O2+ ions at energies as low as 13 eV, and discuss this behaviour in terms of ion–molecule reactions. The desorbed CO+ ion yield shows resonances at ?15.4 and ?17 eV, below the gas-phase thermodynamic threshold

  17. Influence of iodine on the treatment of spacecraft humidity condensate to produce potable water

    NASA Technical Reports Server (NTRS)

    Symons, James M.; Muckle, Susan V.

    1990-01-01

    Several compounds in the ersatz humidity condensate do react with iodine to form iodine-substituted organic compounds (TOI), most notably phenol, acetaldehyde, ethanol, and sodium formate. Iodination of the ersatz humidity condensate produced 3.0 to 3.5 mg/L of TOI within 24 hours. The TOI that was produced by the passage of the ersatz humidity condensate through the first iodinated resin (IR) in the adsorption system was removed by the granular activated carbon that followed. TOI detected in the final effluent was formed by the reaction of the non-adsorbable condensate compounds with the final IR in the treatment series. The activated carbon bed series in the adsorption system performed poorly in its removal of TOC. The rapid breakthrough of TOC was not surprising, as the ersatz humidity condensate contained several highly soluble organic compounds, alcohols and organic acids.

  18. Counterion Correlations on Condensed Biopolymers

    NASA Astrophysics Data System (ADS)

    Angelini, Tommy; Butler, John; Ho, James; Liang, Hongjun; Wong, Gerard

    2002-03-01

    Like-charged polyelectrolytes condense into ordered phases in the presence of multivalent ions. The physical origin of the attractive interaction required for this condensation has been intensely debated, but no clear consensus has emerged, although counterion correlations appear to play a key role. In order to elucidate the nature of these interactions, we have performed structural measurements of condensed phases formed between multivalent ions and a range of rod-like polyelectrolytes, including cytoskeletal F-actin, and Fd and M13 filamentary virus particles.šDirect measurements of the counterion density and correlations in different condensed phases will be presented, along with the temperature dependence of these phases. This work was supported by NSF DMR-0071761, DOE DEFG02-91ER45439, the Beckman Young Investigator Program, and the Cystic Fibrosis Foundation.

  19. Mycolic acid biosynthesis: definition and targeting of the Claisen condensation step

    Microsoft Academic Search

    Richard E Lee; Jason W Armour; Kuni Takayama; Patrick J Brennan; Gurdyal S Besra

    1997-01-01

    Through the use of 2,2-[2H]palmitic acid pulse labeling of the whole cells of C. matruchotti and analysis by gas chromatography-mass spectrometry of the non-labeled and [2H]-labeled corynomycolates, we established a new mechanism for palmitate condensation devoid of the postulated carboxylation step. This evidence allowed the design and synthesis of several structurally related antagonists against the condensation reactions which were shown

  20. Temperature-based model for condensed-phase explosive detonation

    NASA Astrophysics Data System (ADS)

    Desbiens, Nicolas; Matignon, Christophe; Sorin, Remy; Dubois, Vincent

    2013-06-01

    Simple reactive flow models for condensed explosives have four requirements: two equations of state (EOS), one for the unreacted condensed-phase explosive, and one for its detonation products, a reaction rate law that converts the explosive in products and a mixture rule to compute the biphasic partially reacted states. Generally, the chemical reaction rates are governed by local temperature. Nonetheless, temperature fields are scarcely known, especially in detonating condensed-phase explosives. Hence this quantity is not provided by the usual unreacted explosive EOS with the required accuracy. As a consequence, for shock initiation and detonation phenomena, rate laws are based on easily measurable properties such as pressure, compression or particle velocity. In this work, we build an EOS for a TATB-based explosive that provides a better estimate of the shocked explosive temperature. This EOS is derived from ab initio simulation results of monocristalline TATB. Then the well-known pressure-based WSD reaction rate law is rewritten to be temperature-dependent. This model is expected to give interesting results as regards shock desensitization and initial conditions variations while remaining very accurate for detonation propagation. Preliminary results will be shown.