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1

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

PubMed

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

Qian, Xianghong; Liu, Dajiang

2014-03-31

2

The Formation Of Glycerol Monodecanoate By A Dehydration Condensation Reaction: Increasing The Chemical Complexity Of Amphiphiles On The Early Earth  

NASA Astrophysics Data System (ADS)

Dehydration/condensation reactions between organic molecules in the prebiotic environment increased the inventory and complexity of organic compounds available for self-assembly into primitive cellular organisms. As a model of such reactions and to demonstrate this principle, we have investigated the esterification reaction between glycerol and decanoic acid that forms glycerol monodecanoate (GMD). This amphiphile enhances robustness of self-assembled membranous structures of carboxylic acids to the potentially disruptive effects of pH, divalent cation binding and osmotic stress. Experimental variables included temperature, water activity and hydrolysis of the resulting ester product, providing insights into the environmental conditions that would favor the formation and stability of this more evolved amphiphile. At temperatures exceeding 50 ?C, the ester product formed even in the presence of bulk water, suggesting that the reaction occurs at the liquid interface of the two reactants and that the products segregate in the two immiscible layers, thereby reducing hydrolytic back reactions. This implies that esterification reactions were likely to be common in the prebiotic environment as reactants underwent cycles of wetting and drying on rare early landmasses at elevated temperatures

Apel, Charles L.; Deamer, David W.

2005-08-01

3

Prebiotic condensation reactions in an aqueous medium: A review of condensing agents  

Microsoft Academic Search

Biopolymers are formed by dehydration-type condensation reactions. In aqueous solutions dehydration reactions are very unlikely to happen spontaneously. However, coupling of dehydration-condensation to the hydrolysis of condensing agents could facilitate the synthesis of biopolymers in an aqueous solution. The literature shows that the peptides, nucleosides, nucleotides and oligonucleotides can be formed in this way. A careful study of the literature

Josée Hulshof; Cyril Ponnamperuma

1976-01-01

4

The formation of glycerol monodecanoate by a dehydration/condensation reaction: increasing the chemical complexity of amphiphiles on the early earth  

NASA Astrophysics Data System (ADS)

Dehydration/condensation reactions between organic molecules in the prebiotic environment increased the inventory and complexity of organic compounds available for self-assembly into protocellular structures. As a model of such reactions, we have investigated the esterification reaction between glycerol and decanoic acid that forms glycerol monodecanoate. This amphiphile enhances robustness of self-assembled membranous structures of carboxylic acids to the potentially disruptive effects of pH, divalent cation binding and osmotic stress. Experimental variables included temperature, water activity and hydrolysis of the resulting ester product, providing insights into the environmental conditions that would favour the formation and stability of this more evolved amphiphile. At temperatures exceeding 500 C, the ester product formed even in the presence of bulk water, suggesting that the reaction occurs at the liquid interface of the two reactants and that the products segregate in the two immiscible layers, thereby reducing the rate of the hydrolytic back reaction. This suggests that esterification reactions were likely to commonly occur in the prebiotic environment as available reactants underwent cycles of wetting and drying on early landmasses at elevated temperatures.

Apel, C. L.; Deamer, D. W.

5

Prebiotic condensation reactions using cyanamide  

NASA Technical Reports Server (NTRS)

Condensation reactions in cyanamide, 4-amino-5-imidazole-carboxamide and cyanamide, imidazole systems under dehydrating conditions at moderate temperatures (60 to 100 deg C) were investigated. The cyanamide, imidazole system was used for synthesis of palmitoylglycerols from ammonium palmitate and glycerol. With the addition of deoxythymidine to the former system, P1, P2-dideoxythymidine 5 prime-phosphate was obtained; the same cyanamide, 4-amino-5-imidazole-carboxamide system was used to synthesize deoxythymidine oligonucleotides using deoxythymidine 5 prime-phosphate and deoxythymidine 5 prime-triphosphate, and peptides using glycine, phenylalanine or isoleucine with adenosine 5 prime-triphosphate. The pH requirements for these reactions make their prebiotic significance questionable; however, it is conceivable that they could occur in stable pockets of low interlayer acidity in a clay such as montmorillonite.

Sherwood, E.; Nooner, D. W.; Eichberg, J.; Epps, D. E.; Oro, J.

1978-01-01

6

The possible role of solid surface area in condensation reactions during chemical evolution - Reevaluation  

NASA Technical Reports Server (NTRS)

Using surface concentration and reaction rate as the main criteria for the feasibility of condensation reactions, four types of prebiotic environments were analyzed: (1) an ocean-sediment system, (2) a dehydrated lagoon bed produced by evaporation, (3) the surface of a frozen sediment, and (4) a fluctuating system where hydration (rainstorms, tidal variations, flooding) and dehydration (evaporation) take place in a cyclic manner. With the possible exception of nucleotides, low adsorption of organomonomers on sediment surfaces of a prebiotic ocean (pH 8) is expected, and significant condensation is considered unlikely. In dehydrated and frozen systems, high surface concentrations are probable and condensation is more likely. In fluctuating environments, condensation rates will be enhanced and the size distribution of the oligomers formed during dehydration may be influenced by a 'redistribution mechanism' in which adsorbed oligomers and monomers are desorbed and redistributed on the solid surface during the next hydration-dehydration cycle.

Lahav, N.; Chang, S.

1976-01-01

7

Dehydration  

MedlinePLUS

... think you're dehydrated, drink small amounts of water over a period of time. Taking too much all at once can overload your stomach and make you throw up. For people exercising in the heat and losing a lot of minerals in sweat, sports drinks can be helpful. Avoid any drinks that have caffeine.

8

Dehydrative cross-coupling reactions of allylic alcohols with olefins.  

PubMed

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

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

2014-08-25

9

Biofilter application for control of BTEX compounds from glycol dehydrator condenser vent gases at oil and natural gas producing facility  

SciTech Connect

Compliance with 1990 Clean Air Act Amendments will require cost-effective control technologies to reduce air emissions for petroleum industries. EPA has also proposed a new MACT Rule for Oil and Natural Gas Producing Facilities which will require control of emissions from glycol dehydrator vents. Control of volatile organic compound (VOC) emissions such as benzene, toluene, ethylbenzene, and xylene (BTEX) is one of the major concerns for the petroleum industries. Traditional VOC control methods may not be economically feasible to meet the requirements of these regulations. Recent studies have shown that biofilters can cost-effectively remove BTEX compounds with greater than 95% efficiency. This paper describes results from field testing a biofilter at an Oil and Natural Gas Producing facility. The biofilter treats a low flow gas stream containing high concentrations of VOCs and carbon dioxide from a glycol dehydrator condenser vent. A modular high-rate vapor phase biofilter developed by BioiReaction Industries was used to investigate the feasibility of this low-cost technology. Due to the high VOC loading (BTEX compounds up to 18,000 ppm; total VOCs 50,000 to 90,000 ppm), three modular biofilters were installed in series.

Stewart, W.C. [BioiReaction Industries, Inc., Tualatin, OR (United States); Kamarthi, R.S. [Texaco E and P Technology Dept., Bellaire, TX (United States)

1997-12-31

10

Water incorporation in NAMs after antigorite and chlorite dehydration reactions  

NASA Astrophysics Data System (ADS)

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.

Padrón-Navarta, José Alberto; Hermann, Jörg

2014-05-01

11

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

Microsoft Academic Search

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

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

2003-01-01

12

Effect of dehydration reactions on the temperature of faults during coseismic slip  

NASA Astrophysics Data System (ADS)

Recent experimental and theoretical studies have emphasized the possible importance of mineral reactions during coseismic slip. Here we present a series of High Velocity Friction experiments on gypsum solid blocks, performed at Hiroshima University. The temperature close to the sliding surface and the relative humidity around the sample was measured during slip tests at 1.3 m.s-1. The temperature on the sliding surface is remarkably stable during the dehydration reaction of gypsum. Microstructural investigations show that dehydration occurs at the very beginning of the test. Such reactions might be recorded within the wall rock by the presence of anhydrite crystal growth in the hottest parts of the sample. From a theoretical point of view at the fault scale, it is possible to include mineral dehydrations within the framework of Thermal Pressurization. Dehydrations are modeled as a source term for pore pressure because of the total volume change, and a sink term for temperature because they are endothermic. The solution is found numerically, taking into account fluid and heat transport and using an Arrhenius law to calculate the rate constant with temperature. The main effect of dehydration reactions is an increase of pore pressure and a stabilization of the temperature during slip, as illustrated by the HVE on gypsum.

Brantut, Nicolas; Han, Raehee; Alexandre, Schubnel; Toshihiko, Shimamoto; Jérôme, Corvisier

2010-05-01

13

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

SciTech Connect

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.

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

2011-05-01

14

Tandem gold-catalyzed dehydrative cyclization/diels-alder reactions: facile access to indolocarbazole alkaloids.  

PubMed

A gold-catalyzed synthesis of cyclic 2-oxodienes from readily prepared propargyl alcohols and the subsequent Diels-Alder reaction are reported. The dehydrative cyclization reactions proceeded smoothly, and the dienes formed in situ were demonstrated to undergo cycloaddition with a variety of dienophiles. This method offers a new strategy for the synthesis of indolocarbazole alkaloids, whereby the convergent synthetic design allows for differentiation between the indole nitrogens. PMID:25797466

Borrero, Nicholas V; DeRatt, Lindsey G; Ferreira Barbosa, Lais; Abboud, Khalil A; Aponick, Aaron

2015-04-01

15

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

SciTech Connect

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.

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

16

Condensation Reactions and Formation of Amides, Esters, and Nitriles Under Hydrothermal Conditions  

NASA Astrophysics Data System (ADS)

Hydrothermal pyrolysis experiments were performed to assess condensation (dehydration) reactions to amide, ester, and nitrile functionalities from lipid precursors. Beside product formation, organic compound alteration and stability were also evaluated. Mixtures of nonadecanoic acid, hexadecanedioic acid, or hexadecanamide with water, ammonium bicarbonate, and oxalic acid were heated at 300°C for 72 h. In addition, mixtures of ammonium bicarbonate and oxalic acid solutions were used to test the abiotic formation of organic nitrogen compounds at the same temperature. The resulting products were condensation compounds such as amides, nitriles, and minor quantities of N-methylalkyl amides, alkanols, and esters. Mixtures of alkyl amide in water or oxalic acid yielded mainly hydrolysis and dehydration products, and with ammonium bicarbonate and oxalic acid the yield of condensation products was enhanced. The synthesis experiments with oxalic acid and ammonium bicarbonate solutions yielded homologous series of alkyl amides, alkyl amines, alkanes, and alkanoic acids, all with no carbon number predominances. These organic nitrogen compounds are stable and survive under the elevated temperatures of hydrothermal fluids.

Rushdi, Ahmed I.; Simoneit, Bernd R. T.

2004-06-01

17

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 ...

18

The reaction mechanism for dehydration process catalyzed by type I dehydroquinate dehydratase from Gram-negative Salmonella enterica  

NASA Astrophysics Data System (ADS)

The fundamental reaction mechanism for the dehydration process catalyzed by type I dehydroquinate dehydratase from Gram-negative Salmonella enterica has been studied by density functional theory calculations. The results indicate that the dehydration process undergoes a two-step cis-elimination mechanism, which is different from the previously proposed one. The catalytic roles of both the highly conserved residue His143 and the Schiff base formed between the substrate and Lys170 have also been elucidated. The structural and mechanistic insight presented here may direct the design of type I dehydroquinate dehydratase enzyme inhibitors as non-toxic antimicrobials, anti-fungals, and herbicides.

Yao, Yuan; Li, Ze-Sheng

2012-01-01

19

Effect of substituents and hydrogen bonding on barrier heights in dehydration reactions of carbon and silicon geminal diols.  

PubMed

Activation barrier heights for the dehydration reaction of geminal carbinols and silanediols R'R?X(OH)(2) (X = C, Si) were estimated at the B3LYP and MP2 levels of theory employing Dunning's correlation-consistent triple-zeta basis sets. It was shown that the barrier height for carbon derivatives steadily decreases upon substitution by R groups, usually termed as electron-donating, such as alkyl and amino groups. Substitution by electron-withdrawing groups leads, however, only to small changes in barrier heights compared to that of methanediol. A similar tendency was also found for silicon derivatives, but high activation barriers of this reaction remain even for amino group substituted silanediols. Introduction of additional water molecules into the reactive space of carbinol dehydration drastically reduces barrier heights and brings the transition state energy for methanediol close to the experimental value. The difference between dehydration barrier heights for both methanediol and carbinols with electron-rich substituents becomes well-defined for dimeric species. The higher acidity of the hydroxyl group protons in molecules containing halogens and C==O groups brings about a noticeable growth in the dehydration barrier heights of these compounds. This difference in barrier heights for oligomeric species may be the reason for the stability of carbinols with electron-rich substituents. PMID:21946669

Ignatyev, Igor; Montejo, Manuel; Ortega, Pilar Gema Rodríguez; González, Juan Jesús López

2011-11-01

20

Intrinsic and global reaction rate of methanol dehydration over [gamma]Al[sub 2]O[sub 3] pellets  

Microsoft Academic Search

Dehydration of methanol on [gamma]-Al[sub 2]O[sub 3] was studied in a differential fixed-bed reactor at a pressure of 146 kPa in a temperature range of 290-360 [degrees]C. A kinetic equation which describes a Langmuir-Hinshelwood surface controlled reaction with dissociative adsorption of methanol was found to fit the experimental results quite well. Coefficients in the equation follow the Arrhenius and the

G. Bercic; J. Levec

1992-01-01

21

Mechanisms of glycerol dehydration.  

PubMed

Dehydration of neutral and protonated glycerol was investigated using quantum mechanical calculations (CBS-QB3). Calculations on neutral glycerol show that there is a high barrier for simple 1,2-dehydration, E(a)=70.9 kcal mol(-1), which is lowered to 65.2 kcal mol(-1) for pericyclic 1,3-dehydration. In contrast, the barriers for dehydration of protonated glycerol are much lower. Dehydration mechanisms involving hydride transfer, pinacol rearrangement, or substitution reactions have barriers between 20 and 25 kcal mol(-1). Loss of water from glycerol via substitution results in either oxirane or oxetane intermediates, which can inter-convert over a low barrier. Subsequent decomposition of these intermediates proceeds via either a second dehydration step or loss of formaldehyde. The computed mechanisms for decomposition of protonated glycerol are supported by the gas-phase fragmentation of protonated glycerol observed using a triple--quadrupole mass spectrometer. PMID:16671686

Nimlos, Mark R; Blanksby, Stephen J; Qian, Xianghong; Himmel, Michael E; Johnson, David K

2006-05-11

22

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)

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.

Heyne, Joshua S.

23

Onion dehydration  

SciTech Connect

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.

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

1994-07-01

24

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

NASA Astrophysics Data System (ADS)

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.

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

2005-12-01

25

Low-energy electron-induced reactions in condensed matter  

NASA Astrophysics Data System (ADS)

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.

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

2010-01-01

26

Structure-sensitivity and ensemble effects in reactions of strongly adsorbed intermediates. Catalytic dehydrogenation and dehydration of formic acid on nickel  

SciTech Connect

Formic acid (HCOOH) dehydrogenates and dehydrates catalytically on Ni surfaces by unimolecular decomposition of strongly adsorbed formate intermediates. The rate of these reactions and the identity and decomposition selectivity of surface formate are not affected by Ni dispersion or by changes in Ni ensemble size resulting from Cu alloying or from coadsorption of Co and oxygen. Dehydrogenation and dehydration occur via identical intermediates that require small Ni ensembles (1-2 surface atoms) and that decompose with similar activation energy, a surprising result because the required molecular rearrangements differ markedly in the two decomposition modes. The authors suggest that reaction trajectories bifurcate after the formation of the activated complex in the rate-determining formate-decomposition step, leading to two kinetically indistinguishable decomposition paths. The decomposition selectivity on metal catalysts is controlled by entropy differences between the two reaction paths and by the binding energy of adsorbed oxygen atoms on these metal surfaces.

Iglesia, E. (Exxon Research and Engineering Co., Annandale, NJ (United States)); Boudart, M. (Stanford Univ., CA (United States))

1991-09-05

27

Hornblende dehydration reactions during magma ascent at Soufrière Hills Volcano, Montserrat  

Microsoft Academic Search

Hornblende phenocrysts in recent andesites of the Soufrière Hills Volcano display reaction rims of microcrystalline plagioclase,\\u000a pyroxene, Fe-oxides and interstitial glass, formed by decompression during magma ascent. Mass balance calculations give the\\u000a following reactions with mineral proportions in agreement with modal abundances:\\u000a \\u000a \\u000a \\u000a \\u000a $$\\\\begin{aligned} 100.0\\\\,{\\\\text{hbl}} & \\\\to 49.8\\\\,{\\\\text{cpx}} + 27.6\\\\,{\\\\text{opx}} + 18.2\\\\,{\\\\text{plag}} + 4.5\\\\,{\\\\text{Ti - mag}} \\\\\\\\ 100.0\\\\,{\\\\text{hbl}} & \\\\to 53.9\\\\,{\\\\text{cpx}}

V. J. E. Buckley; R. S. J. Sparks; B. J. Wood

2006-01-01

28

Condensation  

NSDL National Science Digital Library

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.

James H. Kessler

2007-01-01

29

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

E-print Network

Reactions of pulsed laser produced boron and nitrogen atoms in a condensing argon stream Lester dilution in argon favored diboron species. At low laser power with minimum radiation, the dominant reaction for argon matrix reactions; instead intense new infrared ab- sorptions, with boron isotopic multiplets, were

Martin, Jan M.L.

30

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

NASA Technical Reports Server (NTRS)

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.

Oskaja, V.; Rotberg, J.

1985-01-01

31

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

Microsoft Academic Search

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

Yeong E. Kim; Thomas O. Passell

2006-01-01

32

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

Microsoft Academic Search

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

Yeong E. Kim; Thomas O. Passell

33

Theory of reversible electron transfer reactions in a condensed phase.  

PubMed

We have derived an exact analytical expression for the average forward rate of a reversible electron transfer reaction, modeled through a reaction coordinate undergoing diffusive motion in arbitrary potential wells of the reactant and the product in presence of a localized sink of arbitrary location and strength. The dynamics of diffusive motion is described by employing two coupled generalized diffusion reaction (Smoluchowski) equations with coordinate dependent diffusivity and delta sink. The average forward electron transfer rate constant obtained here for the system, with equilibrium or nonequilibrium distributions as initial condition, is determined by the forward and backward rate constants calculated based on the transition state theory and the weighted average rate for the well dynamics. We also discuss various limiting cases for the rate of electron transfer reactions corresponding to the different experimental situations. As an illustrative example, we have considered back electron transfer (ET) reaction and shown that the present theory can explain the non-Marcus free energy gap dependence of the rate of ET reactions. More importantly, the approach presented here can easily be extended to systems describing the dynamics of diffusive motion in coupled multipotential surfaces associated with electron transfer reactions. PMID:20866692

Dhole, Kajal; Modak, Brindaban; Samanta, Alok; Ghosh, Swapan K

2010-07-01

34

Glycol dehydrator emission control improved  

SciTech Connect

For natural gas glycol dehydrators, evaporative cooling provides better emission control than conventional air cooled or glycol-cooled condensation technologies. Recent developments in environmental regulations, including the upcoming Maximum Achievable Control Technology (MACT) standards, have made emissions of benzene, ethylbenzene, toluene, and xylenes (BTEX) from glycol dehydrators a major concern for the natural gas industry. This concern has led the gas industry to look for new ways to reduce and control hydrocarbon emissions from these systems. Gas Research institute (GRI) has sponsored the development of the R-BTEX process, which uses evaporative cooling. The paper discusses available technology and then describes the advantages of the R-BTEX process.

Fisher, K.S.; Rueter, C. (Radian Corp., Austin, TX (United States)); Lyon, M. (Public Service Co. of Colorado, Denver, CO (United States)); Gamez, J. (Gas Research Inst., Chicago, IL (United States))

1995-02-27

35

Nonequilibrium Weak Processes in Kaon Condensation I --- Reaction rate for the thermal kaon process ---  

E-print Network

We investigate the thermal kaon process,in which kaons are thermally produced via nucleon-nucleon collisions.This process is relevant to nonequilibrium dynamics of kaon condensation inside neutron stars.The reaction rates for these processes are calculated, and their temperature and density dependences are compared with those of other reaction rates.It is shown that the thermal kaon process is dominant over other relevant weak reactions throughout the nonequilibrium process, such as the kaon-induced Urca and the modified Urca reactions, and may control the entire evolution of the kaon condensate. The characteristic role of the soft and hard kaons during the evolution is explained, and implications for astrophysical phenomena are briefly discussed.

Takumi Muto; Toshitaka Tatsumi; Naoki Iwamoto

1999-06-09

36

A biocompatible condensation reaction for controlled assembly of nanostructures in live cells  

PubMed Central

Through controlled synthesis and molecular assembly, biological systems are able to organize molecules into supramolecular structures that carry out sophisticated processes. Although chemists have reported a few examples of supramolecular assembly in water, the controlled covalent synthesis of large molecules and structures in vivo has remained challenging. Here we report a condensation reaction between 1,2-aminothiol and 2-cyanobenzothiazole that occurs in vitro and in living cells under the control of pH, disulfide reduction and enzymatic cleavage. In vitro, the size and shape of the condensation products, and nanostructures subsequently assembled, were different in each case and could thus be controlled by tuning the structure of the monomers. Direct imaging of the products obtained in the cells revealed their locations – near the Golgi bodies under enzymatic cleavage control – demonstrating the feasibility of a controlled and localized reaction in living cells. This intracellular condensation process enabled the imaging of the proteolytic activity of furin. PMID:21124381

Liang, Gaolin; Ren, Hongjun; Rao, Jianghong

2011-01-01

37

Imidazole-Catalyzed Henry Reactions in Aqueous Medium  

Microsoft Academic Search

2-Nitroalkanols can be efficiently synthesized using imidazole as a mild Lewis basic catalyst in aqueous medium as well as in organic solvents. The products have been found in good yields without purification (> 95% purity by H NMR) for aromatic aldehydes. Additionally, the very mild reaction conditions prevent the particular side reactions such as aldol condensation, Cannizzaro reaction, or dehydration of

Mridula Phukan; Kalyan Jyoti Borah; Ruli Borah

2008-01-01

38

Probing the Rate-Determining Step of the Claisen-Schmidt Condensation by Competition Reactions  

ERIC Educational Resources Information Center

Competition experiments are a useful tool for preliminary study of the linear free energy relationship of organic reactions. This article describes a physical organic experiment for upper-level undergraduates to identify the rate-determining step of the Claisen-Schmidt condensation of benzaldehyde and acetophenone by studying the linear free…

Mak, Kendrew K. W.; Chan, Wing-Fat; Lung, Ka-Ying; Lam, Wai-Yee; Ng, Weng-Cheong; Lee, Siu-Fung

2007-01-01

39

Measurement of Condensed-Phase Reaction Kinetics in the Aerosol Phase Using Single Particle Mass Spectrometry  

E-print Network

with high efficiency into the vacuum system of the single particle mass spectrometer using an aerodynamics in its infancy.1 Many such materials are produced by spray-pyrolysis techniques in which liquid dropletsMeasurement of Condensed-Phase Reaction Kinetics in the Aerosol Phase Using Single Particle Mass

Zachariah, Michael R.

40

Onion dehydration  

SciTech Connect

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.

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

1995-12-31

41

Photochemical reactions in dehydrated photosynthetic organisms, leaves, chloroplasts and photosystem II particles: reversible reduction of pheophytin and chlorophyll and oxidation of ?-carotene  

NASA Astrophysics Data System (ADS)

Photoreactions of dehydrated leaves, isolated broken chloroplasts and PSII membrane fragments of spinach ( Spinacia oleracea) were studied at different air humidities and compared with photoreactions of dry fronds of a fern, Polypodium vulgare, and a dry lichen, Parmelia sulcata, which in contrast to spinach are insensitive to photoinactivation in the dry state. Even in very dry air, P700 in the reaction center of photosystem I of dry leaves was oxidized, and the primary quinone acceptor Q A in the reaction center of photosystem II was photoreduced by low light. These reactions were only very slowly reversed in the dark and saturated under low light intensity. Light-minus-dark difference absorption spectra of the dry leaves, isolated chloroplasts and PSII membrane fragments measured at higher light intensities revealed absorbance changes of ?-carotene at 500 nm (light-dependent bleaching) and 980 nm (light-dependent band formation) and bleaching of chlorophyll at 436 and 680 nm with appearance of bands at 450 and 800 nm. Decrease of chlorophyll fluorescence upon strong illumination indicated photoaccumulation of a quencher. All these changes were kinetically related and readily reversible. They are interpreted to show light-induced oxidation of ?-carotene (Car) and reduction of chlorophyll-680 (Chl-680) in the reaction center of photosystem II of the dried leaves, chloroplasts and photosystem II particles. The fluorescence quencher was suggested to be Chl-680 - or Car + in close proximity to P680, the primary electron donor. Appreciable photoaccumulation of reduced pheophytin was only observed in dry leaves after Q A reduction had been lost during heat treatment of hydrated leaves prior to dehydration. The observations are interpreted to show light-dependent cyclic electron flow within the reaction center of photosystem II in which Chl-680 (or Pheo) is reduced by P680 * and Car is oxidized by P680 + with consequent recombination of Car + and Chl-680 - (or Pheo -). Cyclic electron flow is thought to be moderately photoprotective by reducing the concentration of the strong oxidant P680 +. Nevertheless, prolonged strong illumination caused considerable photodamage in the dry spinach leaves, much less damage in dry fern fronds and no damage in the dry lichen in which distinct photoreactions were not expressed at light intensities which were effective in dry leaves and fern fronds.

Shuvalov, Vladimir A.; Heber, Ulrich

2003-11-01

42

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

PubMed Central

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

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

2014-01-01

43

First Aid: Dehydration  

MedlinePLUS

... Summer Safety Sun Safety Dehydration Diarrhea Heat Illness Word! Dehydration What's Sweat? What's the Big Sweat About Dehydration? How to Be Safe When You're in the Sun Is It Important to Drink a Lot of Water? Dehydration Contact Us Print Additional resources Send to ...

44

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)

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.

Kim, Yeong E.; Zubarev, Alexander L.

2006-02-01

45

Microwave assisted condensation reactions of 2-aryl hydrazonopropanals with nucleophilic reagents and dimethyl acetylenedicarboxylate.  

PubMed

The reaction of methyl ketones 1a-g with dimethylformamide dimethylacetal (DMFDMA) afforded the enaminones 2a-g, which were coupled with diazotized aromatic amines 3a,b to give the corresponding aryl hydrazones 6a-h. Condensation of compounds 6a-h with some aromatic heterocyclic amines afforded iminoarylhydrazones 9a-m. Enaminoazo compounds 12a,b could be obtained from condensation of 6c with secondary amines. The reaction of 6e,h with benzotriazolylacetone yielded 14a,b. Also, the reaction of 6a,b,d-f,h with glycine and hippuric acid in acetic anhydride afforded pyridazinone derivatives 17a-f. Synthesis of pyridazine carboxylic acid derivatives 22a,b from the reaction of 6b,e with dimethyl acetylenedicarboxylate (DMAD) in the presence of triphenylphosphine at room temperature is also reported. Most of these reactions were conducted under irradiation in a microwave oven in the absence of solvent in an attempt to improve the product yields and to reduce the reaction times. PMID:17960106

Al-Zaydi, Khadijah M; Borik, Rita M

2007-01-01

46

Knoevenagel condensation reaction catalyzed by task-specific ionic liquid under solvent-free conditions  

Microsoft Academic Search

A task-specific ionic liquid, [H3N+–CH2–CH2–OH][CH3COO?] was synthesized and used as catalyst in the Knoevenagel condensation reaction of various kinds of aromatic aldehydes with ethyl cyanoacetate or malononitrile. ?,?-Unsaturated carbonyl compounds were obtained in reasonable yields when the [H3N+–CH2–CH2–OH][CH3COO?] catalyzed Knoevenagel reaction was carried out at room temperature for several to 60min under solvent-free conditions. Only E-isomers were detected. The task-specific

Caibo Yue; Aiqin Mao; Yunyang Wei; Minjie Lü

2008-01-01

47

Oriented growth of garnet by topotactic reactions and epitaxy in high-pressure, mafic garnet granulite formed by dehydration  

E-print Network

Oriented growth of garnet by topotactic reactions and epitaxy in high-pressure, mafic garnet, Shakarparian, 44000 Islamabad, Pakistan ABSTRACT Garnet growth in high-pressure, mafic garnet granulites formed samples preserve a sharp transition in which the low-pressure precursor is replaced by garnet through

Tommasi, Andrea

48

Dehydration kinetics of shocked serpentine  

NASA Technical Reports Server (NTRS)

Experimental rates of dehydration of shocked and unshocked serpentine were determined using a differential scanning calorimetric technique. Dehydration rates in shocked serpentine are enhanced by orders of magnitude over corresponding rates in unshocked material, even though the impact experiments were carried out under conditions that inhibited direct impact-induced devolatilization. Extrapolation to temperatures of the Martian surface indicates that dehydration of shocked material would occur 20 to 30 orders of magnitude more rapidly than for unshocked serpentine. The results indicate that impacted planetary surfaces and associated atmospheres would reach chemical equilibrium much more quickly than calculations based on unshocked material would indicate, even during the earliest, coldest stages of accretion. Furthermore, it is suggested that chemical weathering of shocked planetary surfaces by solid-gas reactions would be sufficiently rapid that true equilibrium mineral assemblages should form.

Tyburczy, James A.; Ahrens, Thomas J.

1988-01-01

49

Gas-Phase Condensation Reactions of SixOyHz- Oxyanions with H2O  

SciTech Connect

Water was reacted with gas-phase oxyanions having the general composition SixOyHz- that were formed and isolated in an ion trap-secondary ion mass spectrometer (IT-SIMS). The radical SiO2- reacted slowly with H2O to abstract HO, forming SiO3H-, at a rate of 8 × 10-13 cm3 molecule-1 s-1, corresponding to an efficiency of about 0.03% compared with the theoretical collision rate constant (average dipole orientation). The product ion SiO3H- underwent a consecutive condensation reaction with H2O to form SiO4H3- at a rate that was approximately 0.4-0.7% efficient. SiO4H3- did not undergo further reaction with water. The multiple reaction pathways by which radical SiO3- reacted with H2O were kinetically modeled using a stochastic approach. SiO3- reacted with water by three parallel reaction pathways: (1) abstraction of a radical H to form SiO3H-, which then reacted with a second H2O to form SiO4H3-; (2) abstraction of a radical OH to form SiO4H-, which further reacted by consecutive H abstractions to form SiO4H2- and then SiO4H3-; and (3) condensation with H2O to form SiO4H2-, which subsequently abstracted a radical H from a second H2O to form SiO4H3-. In all of these reactions, the rate constants were determined to be very slow, as determined by both direct measurement and stochastic modeling. For comparison, the even electron ion Si2O5H- was also investigated: it underwent condensation with H2O to form Si2O6H3-, with a rate constant corresponding to 50% efficiency. The reactions were also modeled using ab initio calculations at the UB3LYP/6-311+G(2d,p) level. Addition of H2O to SiO3-, SiO3H-, and Si2O5H- was calculated to be approximately 42, 45, and 55 kcal mol-1 exothermic, respectively, and encountered low activation barriers. Modeling of SiO2- and SiO3- reactions with H2O failed to produce radical abstraction reaction pathways observed in the IT-SIMS, possibly indicating that alternative reaction mechanisms are operative.

Groenewold, Gary Steven; Scott, Jill Rennee; Gianotto, Anita Kay; Hodges, Brittany DM; Kessinger, Glen Frank; Benson, Michael Timothy; Wright, J. B.

2001-09-01

50

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

Microsoft Academic Search

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)Cl3 provided in low yield a single C–N condensation product 1 (at the primary terminal

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

2005-01-01

51

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

Microsoft Academic Search

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 alpha-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)Cl3 provided in low yield a single C N condensation product 1 (at the primary

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

2005-01-01

52

Direct dehydrative N-Pyridinylation of amides, the interrupted Bischler-Napieralski reaction, and the enantioselective total synthesis and arylative dimerization of aspidosperma alkaloids  

E-print Network

I. Direct Dehydrative N-Pyridinylation of Amides A method for the single-step N-pyridinylation of secondary amides is described. The process involves electrophilic activation of secondary amides with trifluoromethanesulfonic ...

Medley, Jonathan William

2013-01-01

53

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

NASA Astrophysics Data System (ADS)

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.

Kim, Yeong E.; Passell, Thomas O.

2006-02-01

54

In-place condensation of reaction mixture using hollow fiber membrane reactors improved productivity of cell-free protein synthesis  

Microsoft Academic Search

The authors intended to raise the protein production rate of continuous flow cell-free (CFCF) translation by applying in-place condensation of the reaction mixture containing wheat germ extract (WGE), mRNA, tRNA, amino acids, and high energy biochemicals. A hollow fiber membrane reactor (HFMR) composed of a shell and 80 hollow fibers made of ultrafiltration (UF) membrane was developed for condensing the

Yuichi Yamamoto; Shunjiro Sugimoto; Xin-chun Shen; Teruyuki Nagamune; Shui-liang Yao; Eiji Suzuki

1999-01-01

55

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

SciTech Connect

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.

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

2014-03-28

56

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

SciTech Connect

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.

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

2014-11-21

57

Dehydration, dehydrogenation, and condensation of alcohols on supported oxide catalysts based on cyclic (WO3)3 and (MoO3)3 clusters.  

PubMed

Supported early transition metal oxides have important applications in numerous catalytic reactions. In this article, we review the synthesis and activity of well-defined model WO3 and MoO3 catalysts that are 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/ketones, and ethers is employed to probe the structure-activity relationships on model 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. The catalytic activity for a range of interrogated (WO3)3 motifs (from unsupported clusters to nanoporous films) further sheds light onto the role structure and binding of (WO3)3 clusters with the support play in determining their catalytic activity. PMID:24553750

Rousseau, Roger; Dixon, David A; Kay, Bruce D; Dohnálek, Zdenek

2014-11-21

58

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

PubMed Central

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

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

1996-01-01

59

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

SciTech Connect

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.

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

60

OSMOTIC DEHYDRATION OF PINEAPPLE  

Microsoft Academic Search

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

D. Saputra

2001-01-01

61

Reaction rates as a function of scale within ionic liquids: microscale in droplet microreactors versus macroscale reactions in the case of the Grieco three-component condensation reaction.  

PubMed

Task-specific ionic liquids (TSILs) and more specifically binary task-specific ionic liquids (BTSILs), a unique subclass, have been shown to be excellent supports for solution-phase chemistry. The negligible volatility of ionic liquids enables their use as stable droplet microreactors in atmospheric environments without oil protection or confinement. These droplets can be moved, merged and mixed by electrowetting on a chip. Solution-phase synthesis can be performed on these open digital microfluidic labs-on-a-chip as illustrated by a study of the Grieco three-component reaction in [tmba][NTf(2)]-droplet (tmba=N-trimethyl-N-butylammonium NTf(2)=bis(trifluoromethylsulfonyl)imide) microreactors. A detailed study of matrices and scale effects on conversion and kinetic rates of this three-component condensation is presented in this paper. Reactions have been shown to be slower in droplets than in batches in the absence of additional mixing. Also, a significant influence of the ionic-liquid matrix has been observed. Finally, an increase of droplet's temperature resulted in a kinetics enhancement so as to reach macroscale reaction rates, probably because of a much better mixing of reaction's components involving a Marangoni's effect. PMID:17506052

Dubois, Philippe; Marchand, Gilles; Gmouh, Said; Vaultier, Michel

2007-01-01

62

Charge constrained density functional molecular dynamics for simulation of condensed phase electron transfer reactions  

SciTech Connect

We present a plane-wave basis set implementation of charge constrained density functional molecular dynamics (CDFT-MD) for simulation of electron transfer reactions in condensed phase systems. Following the earlier work of Wu and Van Voorhis [Phys. Rev. A 72, 024502 (2005)], the density functional is minimized under the constraint that the charge difference between donor and acceptor is equal to a given value. The classical ion dynamics is propagated on the Born-Oppenheimer surface of the charge constrained state. We investigate the dependence of the constrained energy and of the energy gap on the definition of the charge and present expressions for the constraint forces. The method is applied to the Ru{sup 2+}-Ru{sup 3+} electron self-exchange reaction in aqueous solution. Sampling the vertical energy gap along CDFT-MD trajectories and correcting for finite size effects, a reorganization free energy of 1.6 eV is obtained. This is 0.1-0.2 eV lower than a previous estimate based on a continuum model for solvation. The smaller value for the reorganization free energy can be explained by the fact that the Ru-O distances of the divalent and trivalent Ru hexahydrates are predicted to be more similar in the electron transfer complex than for the separated aqua ions.

Oberhofer, Harald; Blumberger, Jochen [Department of Chemistry, University of Cambridge, Cambridge CB2 1EW (United Kingdom)

2009-08-14

63

Dynamic effects dictate the mechanism and selectivity of dehydration-rearrangement reactions of protonated alcohols [Me2 (R)CCH(OH2 )Me](+) (R=Me, Et, iPr) in the gas phase.  

PubMed

The gas-phase dehydration-rearrangement (DR) reactions of protonated alcohols [Me2 (R)CCH(OH2 )Me](+) [R=Me (ME), Et (ET), and iPr (I-PR)] were studied by using static approaches (intrinsic reaction coordinate (IRC), Rice-Ramsperger-Kassel-Marcus theory) and dynamics (quasiclassical trajectory) simulations at the B3LYP/6-31G(d) level of theory. The concerted mechanism involves simultaneous water dissociation and alkyl migration, whereas in the stepwise reaction pathway the dehydration step leads to a secondary carbocation intermediate followed by alkyl migration. Internal rotation (IR) can change the relative position of the migrating alkyl group and the leaving group (water), so distinct products may be obtained: [Me(R)CCH(Me)Me???OH2 ](+) and [Me(Me)CCH(R)Me???OH2 ](+) . The static approach predicts that these reactions are concerted, with the selectivity towards these different products determined by the proportion of the conformers of the initial protonated alcohols. These selectivities are explained by the DR processes being much faster than IR. These results are in direct contradiction with the dynamics simulations, which indicate a predominantly stepwise mechanism and selectivities that depend on the alkyl groups and dynamics effects. Indeed, despite the lifetimes of the secondary carbocations being short (<0.5 ps), IR can take place and thus provide a rich selectivity. These different selectivities, particularly for ET and I-PR, are amenable to experimental observation and provide evidence for the minor role played by potential-energy surface and the relevance of the dynamics effects (non-IRC pathways, IR) in determining the reaction mechanisms and product distribution (selectivity). PMID:25179304

de Souza, Miguel A F; Ventura, Elizete; do Monte, Silmar A; Riveros, José M; Longo, Ricardo L

2014-10-13

64

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

65

Electrolyte Concentrates Treat Dehydration  

NASA Technical Reports Server (NTRS)

Wellness Brands Inc. of Boulder, Colorado, exclusively licensed a unique electrolyte concentrate formula developed by Ames Research Center to treat and prevent dehydration in astronauts returning to Earth. Marketed as The Right Stuff, the company's NASA-derived formula is an ideal measure for athletes looking to combat dehydration and boost performance. Wellness Brands also plans to expand with products that make use of the formula's effective hydration properties to help treat conditions including heat stroke, altitude sickness, jet lag, and disease.

2009-01-01

66

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

SciTech Connect

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.

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

67

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

PubMed Central

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 beta 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)beta < (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)beta 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. PMID:24790940

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

2013-01-01

68

A theoretical study of the condensation reactions of methyl cation with ammonia, water, hydrogen fluoride and hydrogen sulphide  

NASA Astrophysics Data System (ADS)

Ab initio molecular orbital calculations have been used to study the condensation reactions of CH 3- with NH 3, H 2O, HF and H 2S. Geometry optimization has been carried out at the Hartree—Fock (HF) level with the split-valence plus d-polarization 6-31G* basis set and improved relative energies obtained from calculations which employ the split-valence plus dp-polarization 6-31G** basis set with electron correlation incorporated via Moller—Plesset perturbation theory terminated at third order (MP3). Zero-point vibrational energies have also been determined and taken into account in deriving relative energies. The structures of the intermediates CH 3XH - (X = NH 2, OH, F and SH) have been obtained and dissociation of these intermediates into CH 2X + + H 2 on the one hand, and CH 3- + HX on the other, has been examined. It is found that for those species for which the methyl condensation reaction is observed to have an appreciable rate (X = NH 2 and SH), the transition structure for hydrogen elimination from CH 3XH - lies significantly lower in energy than the reactants CH 3- + HX (by 75 and 70 kJ mol -1 respectively). On the other hand, for those species for which the methyl condensation reaction is not observed (X = OH and F), the transition structure for H 2 elimination lies higher in energy than CH 3- + HX (by 6 and 87 kJ mol -1 respectively).

Nobes, Ross H.; Radom, Leo

1983-01-01

69

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

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

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

70

Origin of saline, neutral-pH, reduced epithermal waters by reaction of acidic magmatic gas condensates with wall rock  

SciTech Connect

Fluid inclusions in quartz and sphalerite of epithermal veins containing galena, sphalerite and chalcopyrite with silver sulfides and electrum commonly have salinities of 2 to 10 weight percent NaCl equivalent. Examples include Bohemia, OR, Comstock, NV, and Creede, CO. Salinities in such base metal-rich systems are apparently greater than those in gold-adularia, base metal-poor systems such as Sleeper, NV, Republic, WA, and Hishikare, Kyushu. Saline epithermal fluids are commonly assumed to have been derived from saline magmatic brines, from local host formations, as has been suggested for Creede, or from evaporative concentration (boiling) of more dilute meteoric ground water. Another possibility, which may be the most common origin, is reaction of wall rocks with magmatic gas condensates rich in HCl and sulfuric acid. A mixture of one part Augustine Volcanic gas condensate in 10 parts cold ground water has a pH of 0.7 and the dominant cation is H[sup +] by a factor of 10[sup 4]. Calculated reaction of this condensate mixture with andesite at 300 C to a water/rock ratio (w/r) of 4.6 yields an NaCl-dominated fluid with a total salinity of 2.1 wt %. and pH 3.7. Further reaction, to w/r 0.14 yields a fluid salinity of 2.6 wt % and pH of 5.7; this fluid is in equilibrium with a propylitic alteration assemblage. Aqueous sulfide accumulates during the rock reaction as sulfate is reduced to sulfide when ferrous iron is oxidized to ferric iron. Sulfide concentration in the latter fluid is 32 ppm, far exceeding sulfate concentration. In the overall reaction, hydrogen ion is exchanged for base cations (including base metals) and sulfate is reduced to sulfide.

Reed, M.H. (Univ. of Oregon, Eugene, OR (United States). Dept. of Geological Sciences)

1993-04-01

71

An investigation of the role of water on retrograde/condensation reactions and enhanced liquefaction yields. Final report  

SciTech Connect

While great strides have been made in developing the technology of coal liquefaction processes in recent years, many unsolved problems still remain before a viable and economical process can be achieved. The technological problems that still exist can be solved through a more fundamental understanding of the chemistry associated with each stage of the coal liquefaction process, starting with any pretreatment steps that may be carried out on the coal itself. Western Research Institute, under the a contract from the US Department of Energy, has conducted a study of different methods of coal drying as pretreatment steps before liquefaction. The results of that study are the subject of this report. Coals that were dried or partially dried thermally and with microwaves had lower liquefaction conversions than coals containing equilibrium moisture contents. However, chemically dried coals had conversions equal to or greater than the premoisturized coals. The conversion behavior is consistent with changes in the physical structure and cross linking reactions because of drying. Thermal and microwave drying appear to cause a collapse in the pore structure, thus preventing donor solvents such as tetralin from contacting reactive sites inside the coals. Chemical dehydration does not appear to collapse the pore structure. From the study of the kinetics of the chemical dehydration of coals, it was possible to quantify the amount of water on the surface, the amount readily accessible in pores, and the amount more strongly bonded in the internal structure of the coals. The results indicate that high-rank coals have proportionally less surface and easily accessible water than the lower rank coals.

Miknis, F.P.; Netzel, D.A.; Wallace, J.C. Jr.; Butcher, C.H.; Mitzel, J.M.; Turner, T.F.

1995-02-01

72

Rehydration of Dehydrated Foods  

Microsoft Academic Search

Dehydrated products readily take up moisture when immersed in a liquid medium, leading to significant changes in their thermophysical properties. The rehydration kinetics, the structural properties (apparent density, true density, specific volume and internal porosity), the viscoelastic behavior (compression tests), and the flavor losses were investigated during rehydration of various fruits and vegetables. The effect of temperature on the above

M. K. Krokida; C. Philippopoulos

2005-01-01

73

Structural requirements and reaction pathways in condensation reactions of alcohols on Mg{sub y}AlO{sub x} catalysts  

SciTech Connect

The effect of composition and of surface properties on alcohol-coupling reactions was studied on Mg{sub y}AlO{sub x} catalysts using C{sub 2}H{sub 5}OH or {sup 13}CH{sub 3}OH/1-{sup 12}C{sub 3}H{sub 7}OH mixtures as reactants. Samples with Mg/Al ratios of 0.5--9.0 were obtained by thermal decomposition of precipitated hydrotalcite precursors. The nature, density, and strength of surface basic sites were obtained by temperature-programmed desorption (TPD) of CO{sub 2} and by {sup 13}CO{sub 2}/{sup 12}CO isotopic switch methods, whereas the acid site densities were measured by TPD or NH{sub 3}. The catalyst ability for activating H-H bonds was investigated by performing H{sub 2}-D{sub 2} steady-state equilibration reactions. Isotopic tracer studies were carried out in order to probe chain growth pathways in the synthesis of isobutanol. The rates and product selectivity for C{sub 2}H{sub 5}OH or CH{sub 3}OH/C{sub 3}H{sub 7}OH reactions strongly depended on the chemical composition of Mg{sub y}AlO{sub x} samples. In turn, the chemical composition affected the acid-base properties of Mg{sub y}AlO{sub x} samples by modifying surface acid and base site densities and the distribution of strength for such sites. The rate of alcohol dehydration to ethers and olefins increased with increasing Al content. Al-rich Mg{sub y}AlO{sub x} samples contained a high density of Al{sup 3+}{minus}O{sup 2{minus}} site pairs and of moderate strength basic sites, the combination of which promoted the formation of ethylene or propylene from primary alcohols via E{sub 2} elimination pathways. The competitive dehydration to form ethers involved the adsorption of two alcohol molecules on neighboring active sites offering different acid-base properties.

Di Cosimo, J.I.; Apesteguia, C.R.; Gines, M.J.L.; Iglesia, E.

2000-03-10

74

Aromatic Recovery Unit (ARU): A Process Enhancement for Glycol Dehydrators  

Microsoft Academic Search

A process enhancement to the standard glycol dehydration unit (GDU) was developed to recover hydrocarbons (including the aromatic compounds) normally vented with vapor during glycol regeneration. The gaseous hydrocarbons are recovered as a condensate product (stock-tank oil) and regenerator fuel. This paper describes the technology and proposes a proactive compliance strategy with the US Clean Air Act Amendments (CAAA).

M. S. Choi; C. D. Spisak

1993-01-01

75

Fruits and vegetables dehydration  

NASA Astrophysics Data System (ADS)

Dehydration diagrams were determined by means of Differential Thermal Analysis, DTA, and Thermo Gravimetric Analysis, TGA, curves of several simultaneous fruits and vegetables, all under the same conditions. The greater mass loss is associated with water containing in the structure of the investigated materials at low temperature. In poblano chile water is lost in a single step. The banana shows a very sharply two stages, while jicama can be observed although with a little difficulty three stages. The major mass loss occurs in the poblano chile and the lower in banana. The velocity and temperature of dehydration vary within a small range for most materials investigated, except for banana and cactus how are very different.

de Ita, A.; Flores, G.; Franco, F.

2015-01-01

76

Development of Encapsulation Dehydration  

Microsoft Academic Search

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

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

77

Effect of shock compression on aluminum particle reaction in condensed media  

Microsoft Academic Search

While it is known that aluminum particles, when mixed with an explosive, can react with detonation products and air, the effect that the detonation front has on the onset of aluminum reaction is not well understood. Past experiments have shown a dependence of particle reaction start time on confinement; reaction for 1-10 micrometer particles occurs 1-10 microsec behind the detonation

Akio Yoshinaka; Fan Zhang

2007-01-01

78

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

Microsoft Academic Search

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

F. Cardone; R. Mignani; A. Petrucci

2011-01-01

79

A cost effective method of meeting emission requirements from a 50 MMscfd glycol dehydrator  

SciTech Connect

The removal of volatile organic compounds (VOC) and benzene, toluene, ethylbenzene, xylene (BTEX) from glycol dehydration systems does not require costly equipment or elaborate controls. This paper will describe the design and installation of a 10 equivalent try glycol dehydration unit for field gas dehydration. The absorber design minimizes the absorption of VOC and BTEX by requiring 1.0 to 1.5 gallons of glycol per pound of water removed. Glycol unit VOC emissions are effectively controlled without installing vent gas condensers which require disposal of the waste condensate. The emission control system on this unit is simple to operate, meets emission standards and the dehydrator design achieves pipeline sales gas specifications at a reasonable cost. The system reduces the VOC and BTEX by adding a stripper on the glycol going to the reboiler. A 50 MMscfd dehydrator was installed in December 1995 and the results of an emission test done in April 1997 are presented in this paper.

Gearhart, L.E. [El Paso Field Services Co., Farmington, NM (United States)

1998-12-31

80

[The condensation mechanism of sodium new houttuyfonate and determination of the chemical structure of condensation products].  

PubMed

To study the condensation mechanism of sodium new houttuyfonate, and determinate the chemical structure of condensation products, dimer was prepared, and LC-DAD-MS/MS multiple techniques were employed to investigate the ultraviolet absorption feature and mass spectrum of transformation solution of dimer, and the transformation kinetics and half-life were studied by ultraviolet spectrophotometry. The pure substance of stable condensation product was obtained by extracting with organic solvent and purifying with column chromatography, the chemical structure of this substance was identified by assaying of IR, HR-ESI-MS and NMR, and the data of LC-MS/MS were compared with that of transformation products of dimer. The results indicated that the dimer is unstable, it will be rapidly dissociated in aqueous solution to form free new houttuyfonate and then cycloaddition reaction will occur and followed by an in situ dehydration to generate 1, 3, 5-tri (dodecanoyl) benzene (trimer) with a six-ring which is stable in aqueous solution. The transformation process may fit second-order kinetics, and the half-times were found to be 3.17 hours at 25 degrees C (298 K) and 6.39 min at 100 degrees C (373 K), separately. It suggests that dimer is an intermediate in condensation reaction, and the end condensation product of sodium new houttuyfonate injection may exist as trimer. PMID:19806891

Xu, Rui; Jiang, Ling-Min; He, Jiu-Ming; Liu, Yu-Ling

2009-06-01

81

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

ERIC Educational Resources Information Center

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…

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

2007-01-01

82

Electronic and Ionic Screening For Low-Energy Nuclear Reactions In Condensed Matter  

NASA Astrophysics Data System (ADS)

Screening for nuclear reactions plays an important role in enhancing reaction cross sections at low energy region. In the present work, results so far obtained in experiments of the D+D reactions in metal environment is overviewed and the origin of the screening potential is discussed; i.e., electronic and ionic screening. For the ionic screening we have performed Li+p,d reactions in liquid Li metal which can be regarded as a low-temperature dense plasma. In such a condition, the classical ions contribute to the screening more strongly than the quantum electrons do. The effects of the solid-liquid phase transition are clearly seen in these reactions. It can be concluded that the ionic Debye screening is much stronger than the electronic screening in a low-temperature dense plasmas.

Kasagi, J.; Yonemura, H.

2009-03-01

83

Liquid phase aldol condensation reactions with MgO–ZrO 2 and shape-selective nitrogen-substituted NaY  

Microsoft Academic Search

The aldol condensation reactions of furfural\\/hydroxymethylfurfural (furfurals) with acetone\\/propanal in water–methanol solvents were studied over the solid base catalysts MgO–ZrO2, NaY and nitrogen-substituted NaY (Nit-NaY). The reactions were conducted at 120°C and 750psig of He in batch reactors. Nit-NaY exhibited catalytic activity for aldol condensation comparable to MgO–ZrO2 and much higher than that of NaY, indicative of the increased base

Wenqin Shen; Geoffrey A. Tompsett; Karl D. Hammond; Rong Xing; Fulya Dogan; Clare P. Grey; W. Curtis Conner; Scott M. Auerbach; George W. Huber

2011-01-01

84

Kinetics of volatile extraction from carbonaceous chondrites: Dehydration of talc  

NASA Technical Reports Server (NTRS)

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.

Bose, Kunal; Ganguly, Jibamitra

1991-01-01

85

Survey of quality indicators in commercial dehydrated fruits.  

PubMed

Physical and chemical quality parameters (dry matter, aw, protein, carbohydrates, vitamin C, 2-furoylmethyl amino acids, rehydration ratio and leaching loss) have been determined in 30 commercial dehydrated fruits (strawberry, blueberry, raspberry, cranberry, cherry, apple, grapefruit, mango, kiwifruit, pineapple, melon, coconut, banana and papaya). For comparison purposes, strawberry samples processed in the laboratory by freeze-drying and by convective drying were used as control samples. Overall quality of dehydrated fruits seemed to be greatly dependent on processing conditions and, in a cluster analysis, samples which were presumably subjected to osmotic dehydration were separated from the rest of fruits. These samples presented the lowest concentration of vitamin C and the highest evolution of Maillard reaction, as evidenced by its high concentration of 2-furoylmethyl amino acids. This is the first study on the usefulness of this combination of chemical and physical indicators to assess the overall quality of commercial dehydrated fruits. PMID:24360417

Megías-Pérez, Roberto; Gamboa-Santos, Juliana; Soria, Ana Cristina; Villamiel, Mar; Montilla, Antonia

2014-05-01

86

AN EXPERIMENTAL FRUIT DEHYDRATION SYSTEM  

Microsoft Academic Search

An experimental dehydration system comprising two dehydration units, and in which control and data acquisition functions were computerized, was developed. Product mass is continuously monitored using a built-in weighbridge which facilitates drying rate studies. Product temperatures are also monitored on a continuous basis. Control of wet bulb temperature is achieved by varying the rate of recirculation of air, in conjunction

C. F. Hansmann; G. van Noort

1992-01-01

87

7 CFR 993.15 - Dehydrator.  

Code of Federal Regulations, 2014 CFR

...PRUNES PRODUCED IN CALIFORNIA Order Regulating Handling Definitions § 993.15 Dehydrator. Dehydrator means any person who produces prunes by drying or dehydrating plums by means of sun-drying or artificial...

2014-01-01

88

Dehydration-induced luminescence in clay minerals  

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

89

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

NASA Technical Reports Server (NTRS)

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.

Weber, A. L.

1986-01-01

90

Onion dehydration: a review.  

PubMed

Onion (Allium cepa), a very commonly used vegetable, ranks third in the world production of major vegetables. Apart from imparting a delicious taste and flavour due to its pungency in many culinary preparations, it serves several medicinal purposes also. Processing and preservation of onion by suitable means is a major thrust area since a long time. The various kinds of treatments followed for dehydration of onion such as convective air drying, solar drying, fluidized bed drying, vacuum microwave drying, infrared drying and osmotic drying are reviewed here. These techniques are mainly used for preservation and value addition of onion. Several researchers have tried for decades to model the drying kinetics and quality parameters, which are also compiled here briefly. PMID:23729847

Mitra, Jayeeta; Shrivastava, S L; Rao, P S

2012-06-01

91

7 CFR 989.12 - Dehydrator.  

Code of Federal Regulations, 2010 CFR

...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...

2010-01-01

92

7 CFR 989.12 - Dehydrator.  

Code of Federal Regulations, 2012 CFR

...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...

2012-01-01

93

7 CFR 989.12 - Dehydrator.  

Code of Federal Regulations, 2014 CFR

...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...

2014-01-01

94

7 CFR 989.12 - Dehydrator.  

Code of Federal Regulations, 2011 CFR

...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...

2011-01-01

95

7 CFR 989.12 - Dehydrator.  

Code of Federal Regulations, 2013 CFR

...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...

2013-01-01

96

A Simple Method for Initial Condensed-Phase Combustion Reactions Predictions  

Microsoft Academic Search

Combustion modeling of energetic materials has undergone a tremendous amount of development in recent years. Gas-phase combustion properties predictions are possible and have been shown to agree with experimental results. For solid energetic materials, the gasification reaction products must be determined if gas-phase models are to be applied. The majority of actual models still involve a guessing step for gasification

F. Paquet; H. D. Ng

2011-01-01

97

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

SciTech Connect

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.

RANKIN,STEPHEN E.; MCCORMICK,ALON V.

2000-01-26

98

Condensation reactions of guanidines with bis-electrophiles: Formation of highly nitrogenous heterocyclesa  

PubMed Central

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

Arnold, David M.; LaPorte, Matthew G.; Anderson, Shelby M.; Wipf, Peter

2013-01-01

99

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

E-print Network

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.

F. Cardone; R. Mignani; A. Petrucci

2011-03-06

100

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

E-print Network

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...

Cardone, F; Petrucci, A

2011-01-01

101

Modeling the dehydration of t-butanol and avoidance of the formation of oligomers  

E-print Network

A new mechanistic reaction scheme of the dehydration of t-butanol in sulfuric acid is proposed which) in sulfuric acid is a common way for the produc- tion of very pure isobutene. The dehydration process has been investigated in several pa- pers. Warnecke et al. [1] examined the hydra- tion of isobuten in sulfuric acid

Bothe, Dieter

102

Dehydration products of 2-methylisoborneol  

Microsoft Academic Search

2-Methylenebornane and 2-methyl-2-bornene have previously been identified as dehydration or degradation products of 2-methylisoborneol (MIB), a compound responsible for taste and odour problems in various water environments. Previously, the identification of these products has been based on mass spectral analysis only. The dehydration of MIB under a variety of conditions was reinvestigated and the products fully characterised by 1H and

Russell Schumann; Phillip Pendleton

1997-01-01

103

Effect of dehydration and a few regimes of rehydration on human performance.  

PubMed

The present study was prompted by the controversy about the effect of heat-induced dehydration on human performance, and the popular Indian belief that it is not advisable to take water immediately after prolonged exertion in the sun. The points investigated were: (i) the effect of dehydration on some aspects of physical and mental performance, and (ii) variation in the post-dehydration performance caused by the timing of rehydration. Dehydration amounting to 2% of body weight did not impair mechanical efficiency while 3% dehydration reduced the endurance time for isometric contraction of extensors of the forearm. The maximum isometric tension and mental performance, measured by proof reading and a choice reaction time experiment, were not affected. The studies suggested that once dehydration had been produced, rehydration or its timing did not make any difference. Analysis of the results in terms of the sequence in which the experiments were done suggested the influence of psychological factors on the performance measured. PMID:7216381

Bijlani, R L; Sharma, K N

1980-01-01

104

Dehydration-driven topotaxy in subduction zones  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

105

Dehydrated fluid and seismic deformation in deep subduction zone  

NASA Astrophysics Data System (ADS)

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.

Okamoto, K.

2013-12-01

106

Carbohydrate Dehydration Demonstrations.  

ERIC Educational Resources Information Center

Discusses the impact of various factors on the "charring reaction" of a carbohydrate with concentrated sulfuric acid including the type of sugar, the degree of fineness of the sugar crystals, and the amount of water added. (JRH)

Dolson, David A.; And Others

1995-01-01

107

Osmotic Dehydration Kinetics of Pineapple Wedges using Palm Sugar  

Microsoft Academic Search

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

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

1996-01-01

108

Dehydrative Thiolation of Allenols: Indium vs Gold Catalysis.  

PubMed

Intermolecular additions of thiols to allenols via formal SN2' selectivity to produce functionalized dienes are described. Although this dehydrative reaction was initially developed using gold(I) catalysis, indium(III) proves to be a far superior catalyst in terms of selectivity and substrate scope. PMID:25522131

Webster, S; Young, P C; Barker, G; Rosair, G M; Lee, A-L

2015-02-01

109

Sub-solidus dehydration of amphiboles in an andesitic magma  

NASA Astrophysics Data System (ADS)

Several petrologic experiments have demonstrated that in igneous and metamorphic reactions amphibole minerals can break down by a subsolidus dehydration reaction, but evidence for the reaction in natural rocks has been lacking. Evidence for the breakdown of an edenite-pargasite amphibole by a subsolidus dehydration reaction has now been found in an andesite flow from Garner Mountain, southern Cascase Range. The andesite contains one modal percent of ‘crystal clots’ formed of crystallites of opx, cpx, plag, K-spar, opaque and quartz. The crystal clots retain the original amphibole morphology and intra-clot pyroxenes are aligned with crystallographic c parallel to c in the amphibole precursor; these conditions would not be duplicated by a melting reaction. Microprobe analyses of the bulk clot and the intra-clot minerals suggest the solid-state reaction: 100 amph+10 SiO2=>55 cpx+33 plag+22 opx+ 1 opq+1 kspar Pyroxene thermometry of the andesite groundmass pyroxenes and the intra-clot pyroxenes demonstrates that the amphibole dehydration reaction occurred in the xenocrystic amphiboles as a result of heating by the near-solidus andesite magma.

Mazzone, Peter; Stewart, Dion C.; Hughes, John M.

1987-10-01

110

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)

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.

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

2012-03-01

111

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)

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, 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. 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.

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

2011-12-01

112

Thermoanalytical and microscopic investigations of the thermal dehydration of ?-nickel (II) sulphate hexahydrate  

Microsoft Academic Search

Thermoanalytical (TA) and hot-stage microscopic techniques were employed to investigate the complicated behaviour of the non-isothermal\\u000a dehydration of single crystals of ?-NiSO4·6H2O. Non-isothermal dehydration to the tetrahydrate proceeds in two stages: (1) surface nucleation and growth of nuclei, followed\\u000a by advancement of reaction fronts inward; (2) random nucleation and growth near the reaction front as well as in the bulk.

N. Koga; H. Tanaka

1993-01-01

113

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

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

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

2006-01-01

114

Distortions in the photocycle of bacteriorhodopsin at moderate dehydration.  

PubMed Central

The photoreaction of bacteriorhodopsin was studied in moderately dehydrated films (relative humidities between 100 and 65%). Time-resolved difference spectra from a gated optical multichannel analyzer, between 100 ns and 100 ms after photoexcitation, were decomposed into sums of difference spectra of the intermediates K, L, M, N, and O, and the kinetics obtained were fitted to various alternative schemes. The data confirm the model of a single reaction sequence with reversible reactions we proposed recently for purple membrane suspensions (Váró, G., and J. K. Lanyi. Biochemistry. 1990. 29:2241-2250) but including reversibility also for the reaction K in equilibrium with L in addition to L in equilibrium with M, M in equilibrium with N, and N in equilibrium with O. With increasing dehydration the kinetics were increasingly dominated by the reverse reactions. As before, fitting the data required the existence of two M species in series: L in equilibrium with M1 in equilibrium with M2 in equilibrium with N. The M1 in equilibrium with M2 reaction was greatly slowed at lower humidities. This step might be the switch for the unidirectional transfer of protons. With increasing dehydration recovery of BR occurred less and less via the N intermediate and increasingly via direct shunts from the two M species. As indicated earlier by electrical measurements with similarly dried bacteriorhodopsin films (Váró, G., and L. Keszthelyi, 1983. Biophys. J. 43:47-51). The latter are pathways not necessarily associated with net proton translocation. PMID:2009355

Váró, G; Lanyi, J K

1991-01-01

115

NUMERICAL TECHNIQUES TO SOLVE CONDENSATIONAL AND DISSOLUTIONAL GROWTH EQUATIONS WHEN GROWTH IS COUPLED TO REVERSIBLE REACTIONS (R823186)  

EPA Science Inventory

Noniterative, unconditionally stable numerical techniques for solving condensational and dissolutional growth equations are given. Growth solutions are compared to Gear-code solutions for three cases when growth is coupled to reversible equilibrium chemistry. In all cases, ...

116

An AFM Study of the Effects of Silanization Temperature, Hydration, and Annealing on the Nucleation and Aggregation of Condensed OTS Domains on Mica  

PubMed Central

Partial monolayers of octadecyltrichlorosilane (OTS) were formed on mica under different reaction conditions in which the silanization temperature, time, and amount of water adsorbed on the mica substrates were varied. OTS surface coverage increased with silanization time for all samples; however, the amount and distribution of adsorbed OTS varied greatly under these different reaction conditions. AFM analysis showed that OTS formed two phases on mica silanized at 25°C: condensed “island-like” domains and expanded “liquid-like” domains. Partially dehydrated mica silanized at 9°C, however, displayed only condensed domains which were of smaller size compared to those on the 25°C samples. The lateral diffusion and aggregation of small condensed OTS domains to form larger aggregates was evident on all surfaces except the 25°C partially dehydrated mica. A uniform distribution of many small condensed domains surrounded by expanded OTS phases was seen instead. Extended annealing resulted in surface diffusion and aggregation of these domains and nucleation of new condensed domains from the surrounding expanded OTS phases. These observations are consistent with a deposition, diffusion, and aggregation model (DDA) which allows for activated diffusion; however, rigorous modeling is not presented here. PMID:25125702

Britt, David W.

2012-01-01

117

DFT study of the mechanism of the reaction of aminoguanidine with methylglyoxal.  

PubMed

We have studied the mechanism of the reaction between aminoguanidine (AG) and methylglyoxal (MG) by carrying out Dmol3/DFT calculations, obtaining intermediates, transition-state structures, and free-energy profiles for all of the elementary steps of the reaction. Designed models included explicit water solvent, which forms hydrogen-bond networks around the reactants and intermediate molecules, facilitating intramolecular proton transfer in some steps of the reaction mechanism. The reaction take place in four steps, namely: (1) formation of a guanylhydrazone-acetylcarbinol adduct by condensation of AG and MG; (2) dehydration of the adduct; (3) formation of an 1,2,4-triazine derivative by ring closure; and (4) dehydration with the formation of 5-methyl 3-amino-1,2,4-triazine as the final product. From a microkinetic point of view, the first dehydration step was found to be the rate-determining step for the reaction, with the reaction having an apparent activation energy of 12.65 kcal mol?¹. Additionally, some analogous structures of intermediates and transition states for the reaction between AG and 2,3-dicarbonyl-phosphatidylethanolamine, a possible intermediate in Amadori-glycated phosphatidylethanolamine (Amadori-PE) autooxidation, were obtained to evaluate the reaction above a phosphatidylethanolamine (PE) surface. Our results are in agreement with experimental results obtaining by other authors, showing that AG is efficient at trapping dicarbonyl compounds such as methylglyoxal, and by extension these compounds joined to biomolecules such as PE in environments such as surfaces and their aqueous surroundings. PMID:24705776

Solís-Calero, Christian; Ortega-Castro, Joaquín; Hernández-Laguna, Alfonso; Muñoz, Francisco

2014-04-01

118

Synthesis and some heterocyclisation reactions of CF 2H- and CF 2Cl-substituted 1,1-dicyanoethylenes  

Microsoft Academic Search

New CF2X-analogues of 1,1-dicyano-2,2-bis(trifluoromethyl)ethylene (1) (X=H, Cl) were synthesised by the condensation of polyfluoroketones with malononitrile followed by dehydration using thionyl chloride (or phosphorus pentoxide). The heterocyclisation reactions of new CF2X-analogues of 1,1-dicyano-2,2-bis(trifluoromethyl)ethylene with amidines, 5-aminopyrazoles and 3-methyl-2-pyrazolin-5-ones were systematically investigated.

Alexander S Golubev; Pavel V Pasternak; Alexander F Shidlovskii; Ljudmila N Savelèva; Boris B Averkiev; Vladimir N Nesterov; Michail Yu Antipin; Alexander S Peregudov; Nikolai D Chkanikov

2002-01-01

119

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

PubMed

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

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

2014-09-01

120

The dehydration of SrTeO3(H2O)--a topotactic reaction for preparation of the new metastable strontium oxotellurate(IV) phase ?-SrTeO3.  

PubMed

Microcrystalline single-phase strontium oxotellurate(IV) monohydrate, SrTeO(3)(H(2)O), was obtained by microwave-assisted hydrothermal synthesis under alkaline conditions at 180 °C for 30 min. A temperature of 220 °C and longer reaction times led to single crystal growth of this material. The crystal structure of SrTeO(3)(H(2)O) was determined from single crystal X-ray diffraction data: P2(1)/c, Z = 4, a = 7.7669(5), b = 7.1739(4), c = 8.3311(5) Å, ? = 107.210(1)°, V = 443.42(5) Å(3), 1403 structure factors, 63 parameters, R[F(2)>2?(F(2))] = 0.0208, wR(F(2) all) = 0.0516, S = 1.031. SrTeO(3)(H(2)O) is isotypic with the homologous BaTeO(3)(H(2)O) and is characterised by a layered assembly parallel to (100) of edge-sharing [SrO(6)(H(2)O)] polyhedra capped on each side of the layer by trigonal-prismatic [TeO(3)] units. The cohesion of the structure is accomplished by moderate O-H···O hydrogen bonding interactions between donor water molecules and acceptor O atoms of adjacent layers. In a topochemical reaction, SrTeO(3)(H(2)O) condensates above 150 °C to the metastable phase ?-SrTeO(3) and transforms upon further heating to ?-SrTeO(3). The crystal structure of ?-SrTeO(3), the fifth known polymorph of this composition, was determined from combined electron microscopy and laboratory X-ray powder diffraction studies: P2(1)/c, Z = 4, a = 6.7759(1), b = 7.2188(1), c = 8.6773(2) Å, ? = 126.4980(7)°, V = 341.20(18) Å(3), R(Fobs) = 0.0166, R(Bobs) = 0.0318, Rwp = 0.0733, Goof = 1.38. The structure of ?-SrTeO(3) shows the same basic set-up as SrTeO(3)(H(2)O), but the layered arrangement of the hydrous phase transforms into a framework structure after elimination of water. The structural studies of SrTeO(3)(H(2)O) and ?-SrTeO(3) are complemented by thermal analysis and vibrational spectroscopic measurements. PMID:21479331

Stöger, Berthold; Weil, Matthias; Baran, Enrique J; González-Baró, Ana C; Malo, Sylvie; Rueff, Jean Michel; Petit, Sebastien; Lepetit, Marie Bernadette; Raveau, Bernard; Barrier, Nicolas

2011-05-28

121

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

NASA Technical Reports Server (NTRS)

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.

Rosner, D. E.; Nagarajan, R.

1985-01-01

122

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

NASA Technical Reports Server (NTRS)

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.

Israel, S.

1981-01-01

123

The effect of clay dehydration on land subsidence in the Yun-Lin coastal area, Taiwan  

Microsoft Academic Search

The smectite dehydration theory developed by Ransom and Helgeson was applied for simulation of land subsidence in the Yun-Lin\\u000a coastal area, Taiwan. The volumetric reduction of smectite clay at equilibrium state was computed by assuming that the dehydration\\u000a of interlayer water in smectite clay can be described with a regular solid solution reaction. By using the in situ stratigraphic\\u000a data

C.-W. Liu; W.-S. Lin; C. Shang; S.-H. Liu

2001-01-01

124

Mechanisms of reactions of sulfur hydride hydroxide: tautomerism, condensations, and C-sulfenylation and o-sulfenylation of 2,4-pentanedione.  

PubMed

The conformations, equilibrium structures, hydrogen bonds, and non-covalent interactions involved in the mechanisms of tautomerization, condensations, and C-sulfenylation and O-sulfenylation of 2,4-pentanedione by sulfur hydride hydroxide (hydrogen thioperoxide, oxadisulfane, H-SOH) have been studied using BD(T), CCSD(T), and QCISD(T) with the cc-pVTZ basis set and using B3LYP, B3PW91, CAM-B3LYP, PBE1PBE, PBEh1PBE, LC-?PBE, M06-2X, and ?B97XD with the 6-311+G(d,p) basis set. All levels of theory predict the sulfenyl (H-SOH) tautomer of hydrogen thioperoxide to be lower in energy than the sulfinyl (H2S?O) tautomer. Four reasonable mechanisms were considered for the tautomerization of the sulfenyl tautomer of hydrogen thioperoxide to the sulfinyl tautomer: a cyclic three-membered water-free transition state (TS, CCSD(T) activation energy barrier E(?) = 65.1 kcal/mol), a cyclic five-membered transition state with one water molecule (TSH2O, E(?) = 31.1 kcal/mol), a cyclic seven-membered transition state with two water molecules (TS2H2O, E(?) = 14.5 kcal/mol), and a cyclic nine-membered transition state with three water molecules (TS3H2O, E(?) = 5.6 kcal/mol). The mechanisms involve hydrogen-bonded reactant complexes and hydrogen-bonded product complexes. The CCSD(T)-predicted energy barriers for the condensation of hydrogen thioperoxide to form thiosulfinic acid through transition states with zero, one, and two waters are E(?) = 42.0, 18.3, and 0 kcal/mol, respectively. Mixed condensation reactions are predicted to afford organosulfur products and compounds containing sulfur-selenium bonds. Hydrogen thioperoxide is predicted to add to 2,4-pentanedione to form C-sulfenylated (sulfide, thioether) and O-sulfenylated (sulfenate ester) products. Similar mechanistic trends and reaction pathways are observed in the tautomerism, condensations, and C-sulfenylation and O-sulfenylation reactions of hydrogen thioperoxide. The water molecules set up proton relay networks (bridges) that reduce ring strain, generate favorable conformations for reactivity, lower energy barriers, and increase the numbers of stabilizing hydrogen bonds and nonbonding interactions. PMID:25763808

Freeman, Fillmore

2015-04-01

125

Dehydration  

MedlinePLUS

... Get Help IV (Video) Gastrointestinal Infections and Diarrhea Energy Drinks and Food Bars: Power or Hype? Sports Center Caffeine What's a Healthy Alternative to Water? Contact Us Print Additional resources Send ...

126

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 ...

127

Dehydration in the Elderly: A Short Review  

PubMed Central

Dehydration is the most common fluid and electrolyte problem among the elderly. The usual causes of water loss are frequently absent in dehydrated elderly patients. Age-related changes in total body water, thirst perception, renal concentrating ability, and vasopressin effectiveness probably predispose to dehydration. Dehydration related to infection, high-protein tube feedings, cerebral vascular accidents, and medication-related hypodypsia are particularly relevant for elderly patients. Appropriate treatment depends on accurately assessing the water deficit and slowly correcting that deficit. PMID:3316670

Lavizzo-Mourey, Risa J.

1987-01-01

128

Condensed-Phase, Halogen-Bonded CF3 I and C2 F5 I Adducts for Perfluoroalkylation Reactions.  

PubMed

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 CF3 I and CF3 CF2 I. 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

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

2015-03-16

129

Bifunctional building blocks in the Ugi-azide condensation reaction: A general strategy toward exploration of new molecular diversity†  

PubMed Central

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

Gunawan, Steven; Hulme, Christopher

2013-01-01

130

Spectral effects of dehydration on phyllosilicates  

NASA Technical Reports Server (NTRS)

Six phyllosilicates were progressively dehydrated under controlled conditions in an effort to study the spectral effects of their dehydration. The spectra obtained at each level of hydration provide information that may be used in future spectroscopic observations of the planets, as well as a data set which compliments the existing body of terrestrial soil knowledge.

Bruckenthal, E. A.; Singer, R. B.

1987-01-01

131

Osmotic Dehydration of Tropical Fruits and Vegetables  

Microsoft Academic Search

Because of the microstructural complexity of plant tissue, osmotic dehydration cannot simply be explained as a pure osmotic process in which cell membranes act as a semipermeable barrier allowing water to pass through. Instead, osmotic dehydration is considered a process in which many simultaneous mechanisms, acting at different levels, are responsible for mass transport. Different compositional and structural profiles are

K. O. Falade; J. C. Igbeka

2007-01-01

132

The effect of condensed water on the poorly-soluble volatile organic compounds oxidation: kinetics and mechanism of an aqueous phase isoprene reaction with hydroxyl radical and ozone  

NASA Astrophysics Data System (ADS)

Increasing attention has been paid to the aqueous phase chemistry of organic compounds in the atmosphere. Noticeably, the aqueous phase reaction of the poorly-soluble volatile organic compounds (PSVOCs) has not been much concerned in the atmospheric chemical processes. A number of studies on the adsorption of poorly-soluble gases at air-liquid interface suggested a much higher interface concentration compared to the gas phase concentration. Considering the large global abundance of the poorly-soluble but highly reactive VOCs and the large collective surface of liquid droplets in the atmosphere, it may be important to study the chemical processes of VOCs on the surface of droplets. However, currently little information is available regarding the kinetics and mechanism of the aqueous phase chemical processes of PSVOCs. Here, we focused on the aqueous hydroxyl radical/ozone initiated oxidation of isoprene. For example, we determined the rate constant for the aqueous reaction of isoprene with hydroxyl radical as 1.2 {±}1010 M-1s-1 at 283 K, and observed that the ratio of the yields of MVK to MACR in the aqueous phase isoprene oxidation was approximately double that observed for the corresponding gas phase reaction. On the basis of a box model simulation, we hypothesized that this might be explained by a water-induced enhancement in the self-reaction of a hydroxy isoprene peroxyl radical (HOCH2C(CH3)(O2)CH=CH2) produced in the aqueous reaction. For the aqueous phase ozone oxidation, interestingly, two unknown peroxides were not observed under aqueous conditions, whereas they were detected in the gas phase reaction under dry and humid conditions; the combined yield of MAC and MVK, as well as the total yield of peroxides observed in the aqueous isoprene ozonolysis is much higher than that in the corresponding gas phase reaction under dry and humid conditions. We suggest that these high yields of carbonyls and peroxides are related to the condensed water's greater capability of stabilizing the energy rich Criegee radicals compared with the water vapor. Finally, we evaluated the relative importance of aqueous surface hydroxyl radical/ozone oxidation of isoprene. Our study suggests that air-liquid interface reaction may be an important pathway for atmospheric chemical evolution of isoprene, and the condensed water would considerably affect the kinetics and mechanisms of the reactions. However, further studies are needed for better understanding the relative importance of aqueous chemical processes of isoprene, as well as other PSVOCs, in particular, with an special emphasis on the key parameters, such as the oxidant concentration on the droplet surface, the residence time of PSVOCs on the surface of droplets, and the interface reaction rate constant of the PSVOCs.

Huang, D.; zhang, X.; Wang, H.; Chen, Z.; Zhao, Y.; Shen, X.

2011-12-01

133

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

PubMed Central

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

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

134

Measurement and enhanced monitoring of BTEX and VOC emissions from glycol dehydrators  

SciTech Connect

The Clean Air Act Amendments of 1990 and activities by several states have resulted in increasing regulatory pressure on emissions of benzene, toluene, ethylbenzene, and xylenes (BTEX) and total volatile organic compounds (VOC) from glycol dehydration units. There are no standard sampling and analytical methods established by regulatory agencies for determining emissions from glycol dehydrators, and the methods initially used by the industry showed significant variability in results. To address this lack of methods, the Gas Research Institute (GRI) began an effort to develop measurement methods and emission estimation techniques for glycol dehydrators. Ten methods were evaluated based on the criteria of ease of use, cost, and precision and bias in a series of field experiments at ten sites. The results of the project showed that GRI-GLYCalc should be used to initially screen a large number of units and that atmospheric rich/lean glycol measurements should be made to refine these initial estimates. GRI has also initiated efforts to assist the industry in complying with enhanced monitoring requirements for glycol dehydrators. These enhanced monitoring protocols may be based on using condenser temperatures in conjunction with computer programs such as GRI-GLYCalc. Additional test data will be collected using the methods developed in the previous efforts to validate the computer program predictions for condenser control efficiencies.

Rueter, C.O.; Reif, D.L.; Menzies, W.R.; Evans, J.M.

1995-12-01

135

Condensation cyclization reactions of electron deficient aromatics. 4: Tricyclic nitropropene nitronates from the reaction of phloroglucinol and cycloalkanones with sym-trinitrobenzene  

NASA Technical Reports Server (NTRS)

Interesting similarities have been shown between the reactions of sym-trinitrobenzene with cycloalkanones, and with phloroglucinol. Previously unsuspected common intermediates have been shown to intervene. The structurally similar products in each case are tricyclic nitropropene nitronates. Protonation of these yields the corresponding nitronic acids in certain instances.

Strauss, M. J.; Taylor, S. P. B.; Shindo, H.

1972-01-01

136

Effect of material mass flows on the ignition of condensed systems containing solid-phase reaction products  

Microsoft Academic Search

We consider the problem of ignition of a preheated metallic wire covered with a layer of reagent with a low heat conductivity. Solutions are derived both by numerical and approximate analytical methods. An analysis is presented for the dependence of the critical ignition conditions on the reagent's Stefan flow and the heat release. The degeneration during the reaction of the

A. É. Zakirov; E. A. Nekrasov

1992-01-01

137

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

Microsoft Academic Search

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

Xiaoling Yang; George H. Miley; Heinz Hora

2009-01-01

138

Gas phase dehydration of C 6 alcohols promoted by Y zeolite and supported nafion catalysts  

Microsoft Academic Search

The gas phase dehydration of hexan-1-ol, hexan-2-ol and cyclohexanol (473K?T?573K) has been studied over NaY, HY and Ni\\/NaY zeolites and the action of each has been compared with a commercially available 13% w\\/w Nafion\\/SiO2 composite. The Ni exchanged zeolite and Nafion catalysts exhibited a high selectivity in terms of alkene formation. Condensation to generate the respective ether represented a secondary

Colin Park; Mark A Keane

2001-01-01

139

Field testing results for the R-BTEX{sup {trademark}} process for controlling glycol dehydrator emissions  

SciTech Connect

lncreasing regulatory pressure has made emissions of benzene, toluene, ethylbenzene, and xylenes (collectively known as BTEX) and total volatile organic compounds (VOC) from glycol dehydration units a major concern for the natural gas industry since there are over 40,000 of these units in operation. The Clean Air Act Amendments (CAAA) of 1990 have been the impetus for air toxics regulations, and the Maximum Achievable Control Technology (MACT) standards for the oil and gas industry will be proposed in June, 1995, and will include glycol dehydrators. In addition, several states are regulating or considering regulation of these units. The most common control systems that have been applied to glycol dehydrators are combustion or condensation systems. Combustion systems suffer from high operating costs since they do not recover the hydrocarbon for sale and require supplemental fuel. Many of the condensation systems may not achieve sufficiently low condenser temperatures to meet regulatory control limits. The R-BTEX{sup TM} process addresses this shortcoming by recovering the steam from the glycol dehydrator and converting it to cooling water; this allows R-BTEX to achieve the lowest condenser temperature possible without refrigeration. The Gas Research Institute (GRI) is conducting a field test program to demonstrate the process under a variety of conditions. Under this program, testing has been completed at one site in south Texas and at another site in western Colorado. Startup of a third unit at a Gulf Coast site in Texas should occur in late 1994. This paper presents the testing results for the first two sites and includes a side-by-side comparison of the R-BTEX process with other available control technologies.

Gamez, J.P.; Rueter, C.O.; Beitler, C.M.

1995-12-01

140

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...

141

The kinetics of the bimolecular A+B --> 0 reaction in condensed matter: Effects of non-equilibrium charge screening  

NASA Astrophysics Data System (ADS)

The kinetics of the bimolecular A+B?0 reaction between charged reactants is studied in two dimensions, i.e., on a surface. The theory is based on the Kirkwood superposition approximation for three-particle densities and the self-consistent treatment of the electrostatic interactions defined by the non-uniform spatial distribution of similar and dissimilar reactants. Special attention is paid to pattern formation and many-particle effects arising from reaction-induced formation of loose domains containing similar reactants only. It is shown that the critical exponent ? characterizing the algebraic concentration decay law, n(t)?t-?, differs strongly between symmetric (DA=DB) and asymmetric (DA=0) reactant mobilities. This effect is abnormal from the point of view of standard chemical kinetics. It arises directly from the specific spatial distribution in the system as in ``raisins A in a dough B.'' At long reaction times the asymptotics of the interaction potentials is of non-equilibrium type at large relative distances. The accumulation kinetics in the presence of a permanent source is studied. Results of the microscopic formalism are compared with a previous mesoscopic theory.

Kuzovkov, V. N.; Kotomin, E. A.; von Niessen, W.

1996-12-01

142

Abiotic Condensation Synthesis of Glyceride Lipids and Wax Esters Under Simulated Hydrothermal Conditions  

NASA Astrophysics Data System (ADS)

Precursor compounds for abiotic proto cellular membranes are necessary for the origin of life. Amphipathic compounds such as fatty acids and acyl glycerols are important candidates for micelle/bilayer/vesicle formation. Two sets of experiments were conducted to study dehydration reactions of model lipid precursors in aqueous media to form acyl polyols and wax esters, and to evaluate the stability and reactions of the products at elevated temperatures. In the first set, mixtures of n-nonadecanoic acid and ethylene glycol in water, with and without oxalic acid, were heated at discrete temperatures from 150 ?C to 300 ?C for 72 h. The products were typically alkyl alkanoates, ethylene glycolyl alkanoates, ethylene glycolyl bis-alkanoates and alkanols. The condensation products had maximum yields between 150 ?C and 250 ?C, and were detectable and thus stable under hydrothermal conditions to temperatures < 300 ?C. In the second set of experiments, mixtures of n-heptanoic acid and glycerol were heated using the same experimental conditions, with and without oxalic acid, between 100 ?C and 250 ?C. The main condensation products were two isomers each of monoacylglycerols and diacylglycerols at all temperatures, as well as minor amounts of the fatty acid anhydride and methyl ester. The yield of glyceryl monoheptanoates generally increased with increasing temperature and glyceryl diheptanoates decreased noticeably with increasing temperature. The results indicate that condensation reactions and abiotic synthesis of organic lipid compounds under hydrothermal conditions occur easily, provided precursor concentrations are sufficiently high.

Rushdi, Ahmed I.; Simoneit, Bernd R. T.

2006-04-01

143

Catalytic dehydration of pentaerythritol to dipentaerythritol over heteropoly compounds  

Microsoft Academic Search

Synthesis of dipentaerythritol (DPE) by dehydration of pentaerythritol (PE) has been studied using heteropoly compounds and various solid acids. Heteropoly compounds such as H3PW12O40, H4SiW12O40 and their supported catalysts were found to be effective. The addition of water in the reactant suppressed the consecutive reaction of dipentaerythritol with pentaerythritol over H3PW12O40. Under atmospheric pressure at 463K, silica-supported H3PW12O40 gave 30%

Lianshun Li; Yuichi Kamiya; Toshio Okuhara

2003-01-01

144

Dehydration Linked to Greater Stroke Damage  

MedlinePLUS

... factor out possible effects from age and other variables. Even after adjusting the data, the investigators found that dehydration was still more likely to lead to worse outcomes. Bahouth said that prior research found that about ...

145

Problem: Thirst, Drinking Behavior, and Involuntary Dehydration  

NASA Technical Reports Server (NTRS)

The phenomenon of involuntary dehydration, the delay in full restoration of a body water deficit by drinking, has been described extensively but relatively little is known about its physiological mechanism. It occurs primarily in humans when they are exposed to various stresses including exercise, environmental heat and cold, altitude, water immersion, dehydration, and perhaps microgravity, singly and in various combinations. The level of involuntary dehydration is approximately proportional to the degree of total stress imposed on the body. Involuntary dehydration appears to be controlled by more than one factor including social customs that influence what is consumed, the capacity and rate of fluid absorption from the gastrointestinal system, the level of cellular hydration involving the osmotic-vasopressin interaction with sensitive cells or structures in the central nervous system, and, to a lesser extent, hypovolemic-angiotensin II stimuli. Since humans drink when there is no apparent physiological stimulus, the psychological component should always be considered when investigating the total mechanisms for drinking.

Greenleaf, John E.

1992-01-01

146

DEHYDRATION OF LOW WATER CONTENT ETHANOL  

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 membrane system with suitable flux and selectivity characteristics plays a...

147

Dehydration resistance of liposomes containing trehalose glycolipids  

NASA Astrophysics Data System (ADS)

The pathogen, Mycobacterium tuberculosis, has an unusual outer membrane containing trehalose glycolipids that may contribute to its ability to survive freezing and dehydration. Based on our recent discovery that trehalose glycolipids confer dehydration resistance to supported lipid monolayers (Biophys. J. 94: 4718-4724 (2008); Langmuir 25: 5193-5198, (2009)), we hypothesized that liposomes containing synthetic trehalose glycolipids may be dehydration-resistant as well. To test this, we measured the leakage of encapsulated fluorophores and larger macromolecular cargo from such liposomes subject to freeze drying. Both leakage assays and size measurements show that the liposomes are dehydration-resistant. In addition to demonstrating a possibly technologically useful encapsulation platform, our results corroborate the view that encapsulation in a trehalose-glycolipid-rich membrane is a biophysically viable route to protection of mycobacteria from environmental stresses.

Nyberg, Kendra; Goulding, Morgan; Parthasarathy, Raghuveer

2010-03-01

148

Dehydration processes using membranes with hydrophobic coating  

DOEpatents

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.

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

2013-07-30

149

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

SciTech Connect

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.

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

150

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

NASA Astrophysics Data System (ADS)

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.

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

2009-03-01

151

Linked strategy for the production of fuels via formose reaction.  

PubMed

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

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

2013-01-01

152

Linked strategy for the production of fuels via formose reaction  

PubMed Central

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 C9-C15 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

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

2013-01-01

153

Palladium-Catalyzed Decarbonylative Dehydration of Fatty Acids for the Production of Linear Alpha Olefins  

PubMed Central

A highly efficient palladium-catalyzed decarbonylative dehydration reaction of carboxylic acids is reported. This method transforms abundant and renewable even-numbered natural fatty acids into valuable and expensive odd-numbered alpha olefins. Additionally, the chemistry displays a high functional group tolerance. The process employs low loading of palladium catalyst and proceeds under solvent-free and relatively mild conditions. PMID:24772061

Liu, Yiyang; Kim, Kelly E.; Herbert, Myles B.; Fedorov, Alexey; Grubbs, Robert H.; Stoltz, Brian M.

2014-01-01

154

Catalytic dehydration of methanol to dimethyl ether (DME) over Pd\\/CabOSil catalysts  

Microsoft Academic Search

Ten wt.-% Pd\\/Cab-O-Sil reduced at 300°C has been found to be an effective catalyst for the catalytic dehydration of methanol to dimethyl ether (DME). The presence of hydrogen in the reagent stream inhibited the catalytic activity, but increased the stability of the catalyst. High reaction temperature and low methanol partial pressure did not favor DME formation.

Mingting Xu; D. Wayne Goodman; Alak Bhattacharyya

1997-01-01

155

reactions  

Microsoft Academic Search

Gene regulatory, signal transduction and metabolic networks are major areas of interest in the newly emerging field of systems biology. In living cells, stochastic dynamics play an important role; however, the kinetic parameters of biochemical reactions necessary for modelling these processes are often not accessible directly through experiments. The problem of estimating stochastic reaction constants from molecule count data measured,

S. Reinker; R. M. Altman; J. Timmer

156

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

NASA Astrophysics Data System (ADS)

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.

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

2007-12-01

157

Geothermal demonstration: Zunil food dehydration facility  

SciTech Connect

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.

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

158

Leveraging the Micellar Effect: Gold-Catalyzed Dehydrative Cyclizations … in Water at Room Temperature  

PubMed Central

The first examples of gold-catalyzed cyclizations of diols and triols to the corresponding hetero- or spirocycles in a bulk aqueous medium are presented. These reactions take place within nanomicelles, where the hydrophobic effect is operating, thereby driving the dehydrations, notwithstanding the surrounding water. By the addition of simple salts such as sodium chloride, reaction times and catalyst loadings can be significantly decreased. PMID:24433154

Minkler, Stefan R. K.; Isley, Nicholas A.; Lippincott, Daniel J.

2014-01-01

159

Cyclization reactions of 1-[3'-hydroxy-2'-(hydroxymethyl)prop-1'-enyl]pyrimidine nucleobases: intramolecular Michael additions to the C(5)=C(6) bonds and intramolecular dehydrations.  

PubMed

The tendency of a series of acyclic nucleoside analogues 1a-f to undergo intramolecular cyclization reactions was investigated. All compounds, when treated with NaOD, were in equilibrium with the bicyclic compounds 2a-f, arising from Michael addition of a hydroxy group to the C(5)=C(6) bonds. Derivatives of 2,4-pyrimidinediones (1a,b) had the highest tendency to undergo intramolecular Michael addition when treated with triethylamine, whereas the cyclization of 4-amino-2-pyridones (1c-f) proceeded best with acid. The exocyclic double bond of was essential for the cyclization to occur. Commonly used N-protecting groups as the benzoyl- and the dibutylaminomethylene group enhanced cyclization. Under acidic anhydrous conditions 1b and 1e cyclized to the 2,4'-anhydro compounds 1b and 1e. PMID:15889180

Dahl, Otto; Jensen, Jacob; Petersen, Michael Axman; Henriksen, Ulla

2005-05-21

160

Effect of enzyme dehydration on alcalase-catalyzed dipeptide synthesis in near-anhydrous organic media.  

PubMed

The effect of enzyme dehydration by molecular sieves on the coupling of phenylalanine amide and the carbamoylmethyl ester of N-protected phenylalanine in near-anhydrous tetrahydrofuran was investigated. This coupling was catalyzed by Alcalase covalently immobilized onto macroporous acrylic beads (Cov); these immobilized enzymes were hydrated prior to use. The dehydration kinetics of Cov by molecular sieve powder were determined by incubating Cov with different amounts of molecular sieve powder for different periods of time (0-80 h). Subsequently, the remaining coupling activity of Cov was measured. Dehydration-induced inactivation of Cov by molecular sieve powder was found to occur in three phases: (1) an initial, rapid, major dehydration-induced inactivation that takes place during the first activity measurement, (2) a phase of first-order inactivation, and (3) a plateau phase in activity. These dehydration kinetics were incorporated into a previously found reaction kinetics model. The resulting model was then used to fit progress curve data of the coupling in the presence of different amounts of molecular sieve powder. Upon establishment of parameter values, the model was used to predict independent data sets and found to work well. PMID:23554404

Vossenberg, Petra; Beeftink, Rik; Stuart, Martien Cohen; Tramper, Hans

2013-01-01

161

Ethanol Dehydration in HZSM-5 Studied by Density Functional Theory: Evidence for a Concerted Process.  

PubMed

Dehydration over acidic zeolites is an important reaction class for the upgrading of biomass pyrolysis vapors to hydrocarbon fuels or to precursors for myriad chemical products. Here, we examine the dehydration of ethanol at a Brønsted acid site, T12, found in HZSM-5 using density functional theory (DFT). The geometries of both cluster and mixed quantum mechanics/molecular mechanics (QM:MM) models are prepared from the ZSM-5 crystal structure. Comparisons between these models and different DFT methods are conducted to show similar results among the models and methods used. Inclusion of the full catalyst cavity through a QM:MM approach is found to be important, since activation barriers are computed on average as 7 kcal mol(-1) lower than those obtained with a smaller cluster model. Two different pathways, concerted and stepwise, have been considered when examining dehydration and deprotonation steps. The current study shows that a concerted dehydration process is possible with a lower (4-5 kcal mol(-1)) activation barrier while previous literature studies have focused on a stepwise mechanism. Overall, this work demonstrates that fairly high activation energies (?50 kcal mol(-1)) are required for ethanol dehydration. A concerted mechanism is favored over a stepwise mechanism because charge separation in the transition state is minimized. QM:MM approaches appear to provide superior results to cluster calculations due to a more accurate representation of charges on framework oxygen atoms. PMID:25802969

Kim, Seonah; Robichaud, David J; Beckham, Gregg T; Paton, Robert S; Nimlos, Mark R

2015-04-16

162

Dehydration behavior of the superprotonic conductor CsH2PO4 at moderate temperatures: 230 to 260 uC{  

E-print Network

parameters of the dehydration reaction from CsH2PO4 to CsPO3 were evaluated. The dehydration pathway metaphosphate CsPO3, the reaction occurs via two overlapping steps: CsH2PO4 A Cs2H2P2O7 A CsPO3, with solid intermediate between those of a normal salt and an acid, and it undergoes a transition from a paraelectric

163

Atmospheric Aerosols and Cloud Condensation Nuclei  

E-print Network

Supersaturated Environment With Respect To Water Grow to Form Droplet Diffusion Chamber for Cloud CondensationAtmospheric Aerosols and Cloud Condensation Nuclei March 21, 2013: Looking West towards East Grand for Chemical Reactions Serve as Cloud Condensation Nuclei CCN) #12;Objectives Provide an introduction

Delene, David J.

164

Hydration-dehydration, heat, humidity, and "cool, clear, water".  

PubMed

Personal recollections of dehydration meltdowns during the Kona Ironman Triathlon, reflections on their cause, and the author's experiential recommendations regarding hydration, prevention of dehydration, and "beat the heat and humidity" measures. PMID:23147099

Lockett, Lawrence J

2012-12-01

165

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...

166

21 CFR 73.40 - Dehydrated beets (beet powder).  

Code of Federal Regulations, 2014 CFR

...Identity. (1) The color additive dehydrated beets is a dark red powder prepared by dehydrating sound, mature, good quality...additive shall conform to the following specifications: Volatile matter, not more than 4 percent. Acid insoluble ash, not...

2014-04-01

167

21 CFR 73.40 - Dehydrated beets (beet powder).  

Code of Federal Regulations, 2012 CFR

...Identity. (1) The color additive dehydrated beets is a dark red powder prepared by dehydrating sound, mature, good quality...additive shall conform to the following specifications: Volatile matter, not more than 4 percent. Acid insoluble ash, not...

2012-04-01

168

21 CFR 73.40 - Dehydrated beets (beet powder).  

Code of Federal Regulations, 2011 CFR

...Identity. (1) The color additive dehydrated beets is a dark red powder prepared by dehydrating sound, mature, good quality...additive shall conform to the following specifications: Volatile matter, not more than 4 percent. Acid insoluble ash, not...

2011-04-01

169

21 CFR 73.40 - Dehydrated beets (beet powder).  

Code of Federal Regulations, 2013 CFR

...Identity. (1) The color additive dehydrated beets is a dark red powder prepared by dehydrating sound, mature, good quality...additive shall conform to the following specifications: Volatile matter, not more than 4 percent. Acid insoluble ash, not...

2013-04-01

170

21 CFR 73.40 - Dehydrated beets (beet powder).  

Code of Federal Regulations, 2010 CFR

...Identity. (1) The color additive dehydrated beets is a dark red powder prepared by dehydrating sound, mature, good quality...additive shall conform to the following specifications: Volatile matter, not more than 4 percent. Acid insoluble ash, not...

2010-04-01

171

Thermoelastic behavior and dehydration process of cancrinite  

NASA Astrophysics Data System (ADS)

The high-temperature thermoelastic behavior of a natural cancrinite has been investigated by in situ single-crystal X-ray diffraction. The unit-cell volume variation as a function of temperature ( T) exhibits a continuous trend up to 748 K (hydrous expansion regime). The unit-cell edges expansion clearly shows an anisotropic expansion scheme ( ? a < ? c ). At 748 K, a dehydration process takes place, and a series of unit-cell parameter measurements at constant temperature (748 K) for a period of 12 days indicate that the dehydration process continued for the entire period of time, until the cell parameters were found to be constant. After the dehydration process is completed, the structure expands almost linearly with increasing temperature up to 823 K, where a sudden broadening of the diffraction peaks, likely due to the impending decomposition, did not allow the collection of further data points. Even with a very limited temperature range for the anhydrous regime, we observed that the behavior of the two (i.e., hydrous and anhydrous) high-temperature structures is similar in terms of (1) volume thermal expansion coefficient and (2) thermoelastic anisotropy. The structure refinements based on the data collected at 303, 478 and 748 K (after the dehydration), respectively, showed a change in the mechanism of tilting of the quasi-rigid (Si,Al)O4 tetrahedra, following the loss of H2O molecules, ascribable to the high-temperature Na+ coordination environment within the cages.

Gatta, G. D.; Comboni, D.; Alvaro, M.; Lotti, P.; Cámara, F.; Domeneghetti, M. C.

2014-05-01

172

Pelagic sea snakes dehydrate at sea.  

PubMed

Secondarily marine vertebrates are thought to live independently of fresh water. Here, we demonstrate a paradigm shift for the widely distributed pelagic sea snake, Hydrophis (Pelamis) platurus, which dehydrates at sea and spends a significant part of its life in a dehydrated state corresponding to seasonal drought. Snakes that are captured following prolonged periods without rainfall have lower body water content, lower body condition and increased tendencies to drink fresh water than do snakes that are captured following seasonal periods of high rainfall. These animals do not drink seawater and must rehydrate by drinking from a freshwater lens that forms on the ocean surface during heavy precipitation. The new data based on field studies indicate unequivocally that this marine vertebrate dehydrates at sea where individuals may live in a dehydrated state for possibly six to seven months at a time. This information provides new insights for understanding water requirements of sea snakes, reasons for recent declines and extinctions of sea snakes and more accurate prediction for how changing patterns of precipitation might affect these and other secondarily marine vertebrates living in tropical oceans. PMID:24648228

Lillywhite, Harvey B; Sheehy, Coleman M; Brischoux, François; Grech, Alana

2014-05-01

173

Geothermal demonstration: Zunil food dehydration facility  

Microsoft Academic Search

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

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

1991-01-01

174

Sour gas dehydration in Mobile Bay  

SciTech Connect

An evaluation of Mobil`s different methods of sour gas development utilized offshore and processes selected are presented with the maintenance history. The conclusions are based on field data showing past performance with a correlation made for future development and the selection criteria for dehydration.

Betts, F.C. Jr.; Lay, A.G.

1996-12-31

175

Thermodynamic stability considerations for isostructural dehydrates.  

PubMed

Nonstoichiometric channel hydrates are a class of crystalline hydrates that can incorporate a range of water levels as a function of temperature and relative humidity (RH). When a nonstoichiometric channel hydrate can dehydrate to yield a physically stable isostructural crystalline lattice, it may become challenging to accurately evaluate the thermodynamic stability relationship associated with a polymorphic system using traditional methods. This work demonstrates application of a eutectic-melting method to determine the stability relationship between a nonstoichiometric channel dehydrate and an anhydrous form. A transition temperature (122°C) between the isostructural dehydrate of the nonstoichiometric channel hydrate and the anhydrous polymorph was identified, with the nonstoichiometric channel hydrate being the thermodynamically stable anhydrous form at room temperature (RT). Solid-state storage at a range of RH conditions demonstrated that the nonstoichiometric channel hydrate is also the stable form at RT above an RH of 94%. These results demonstrate that the nonstoichiometric channel hydrate is the stable form at low temperatures, independent of its hydration state. It has been demonstrated that the eutectic-melting method is applicable to the study of thermodynamic stability relationships between anhydrous forms and dehydrated channel hydrates. PMID:22262468

Murphy, Brendan J; Casteel, Melissa J; Samas, Brian; Krzyzaniak, Joseph F

2012-04-01

176

Seasonal and Regional Variability of Stratospheric Dehydration  

E-print Network

is coldest and dehydration is occurring at the higher, cooler wintertime maximum. This allows a larger annual oscillation of H2O concentrations than would be expected due to 100-hPa temperature differences alone [e.g. Frederick and Douglass, 1983; Mote et...

Christenberry, Aaron Joseph

2012-07-16

177

Water, water everywhere: dehydration in the elderly.  

PubMed

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

Sacks, Gordon S; Martin, Caren McHenry

2005-11-01

178

Morphokinetic Reaction of Streptococcus faecalis (ATCC 9790) Cells to the Specific Inhibition of Macromolecular Synthesis: Nucleoid Condensation on the Inhibition of Protein Synthesis1  

PubMed Central

In glutaraldehyde-prefixed exponential-phase cells of Streptococcus faecalis the nucleoid is “frozen” in a dispersed configuration. Exposure of exponential-phase cells to threonine starvation or to antibiotics inhibiting protein synthesis resulted in progressive condensation of nucleoid fibrils producing an expanding central nucleoid zone or pool. The condensation of the nucleoid was observed to occur at a rate directly proportional to the rate of inhibition of protein synthesis. However, the extent of nucleoid condensation depended on continuing deoxyribonucleic acid synthesis. Significantly less nucleoid condensation occurred when cells were inhibited in deoxyribonucleic acid and protein synthesis than when cells were inhibited in protein synthesis alone. These results suggest a model in which, during nucleoid replication, the chromosome fibrils are normally maintained in a dispersed state by the active agents of transcription-translation, such as ribonucleic acid polymerase molecules and ribosomes. Images PMID:4110925

Daneo-Moore, Lolita; Higgins, Michael L.

1972-01-01

179

Chemistry and anelasticity in dehydrated sandstone  

NASA Astrophysics Data System (ADS)

Preliminary acoustic measurements of a dehydrated sample of Berea sandstone indicated a dramatic change in elastic and anelastic properties near 45C. With an improved temperature control system we have characterized the change, a softening of the modulus and an increase in dissipation, in detail. We have attempted to fit a finite-element model of a silica grain-bond network to the data and discuss ideas for the connection between water content and nonlinearity. Berea is a complex sandstone with several components beyond the silica frame, so in order to simplify the sample, we are working with a very nonlinear Fontainebleau sandstone and we present new data from both Nonlinear Resonant Ultrasound Spectroscopy (NRUS) and Dynamic Acoustic Elastic Testing on a dehydrated 99.5% silica rock.

Darling, T. W.; Miller, R. A.

2012-12-01

180

Dehydration, Hyperthermia, and Athletes: Science and Practice  

PubMed Central

Objective: To present the recent research that underscores the value of preventing both dehydration and hyperthermia. Such efforts will improve the athlete's capacity to perform physical activity and reduce the risk of heat-related problems. Data Sources: Data were drawn from an extensive review of the scientific literature over the past 50 years with an emphasis on recent research (> 1990) that focuses on the physiological and performance benefits of fluid replacement. Data Synthesis: Even low levels of dehydration (eg, less than a 2% loss of body weight) impair cardiovascular and thermoregulatory response and reduce the capacity for exercise. Heat exposure also reduces the athlete's ability to train and compete, an effect that can be independent of hydration status. Even if athletes are well hydrated, hot weather alone will reduce their capacity to exercise. Optimal performance is possible only when dehydration and hyperthermia are minimized by ingesting ample volumes of fluid during exercise and by taking common-sense precautions in keeping cool. Recent research has demonstrated that consuming fluid in volumes approximating sweat loss maintains important physiological functions and significantly improves exercise performance, even during exercise lasting only 1 hour. Carbohydrate ingestion also improves exercise performance, an effect that is independent of, and additive to, preventing dehydration. Conclusion/Application: Athletes should follow an aggressive fluid replacement and temperature regulation regimen. Successful implementation of this regimen requires that athletic trainers, coaches, athletes, and support personnel are made aware of the benefits of adequate fluid replacement, that appropriate fluid replacement strategies are developed and implemented, that athletes have the opportunity to train themselves to ingest larger volumes of fluid more frequently, and that other practical steps are taken to keep athletes cool during both training and competition. PMID:16558408

Murray, Robert

1996-01-01

181

Calcium hydroxide dehydration early precursor states  

Microsoft Academic Search

A neutron and X-ray diffraction study of coarsely polycrystalline Ca(OD)2 shows that approximately 50°C below the onset temperature of dehydration, which is sensitive to the water partial pressure, slight structural modifications occur. They manifest themselves by a sudden sharpening of the 001 reflection and by a decrease in the slope of the 001 intensity vs temperature plots. The initially broad

O. Chaix-Pluchery; J. Bouillot; D. Ciosmak; J. C. Niepce; F. Freund

1983-01-01

182

Could Neonatal Hypernatremia Dehydration Influence Hearing Status?  

PubMed Central

Introduction: Neonatal hypernatremia dehydration (NHD) is a dangerous condition in neonates, which is accompanied by acute complications (renal failure, cerebral edema, and cerebral hemorrhage) and chronic complications (developmental delay). Children begin learning language from birth, and hearing impairment interferes with this process. We assessed the hearing status of infants with hypernatremia dehydration. Materials and Methods: In a case-control study in 110 infants presenting at the Ghaem Hospital (Mashhad, Iran) between 2007 and 2011, we examined the incidence of hearing impairment in infants suffering from hypernatremia dehydration (serum sodium >150 mEq/L) in comparison with infants with normal sodium level (serum sodium ?150 mEq/L). Results: Three of 110 cases examined in the study group showed a transient hearing impairment. A mean serum sodium level of 173mg/dl was reported among hearing-impaired infants. Conclusion: Transient hearing impairment was higher in infants with hypernatremia; although this difference was not significant (P>0.05). Hearing impairment was observed in cases of severe hypernatremia. PMID:24505569

Boskabadi, Hassan; Anvarifar, Farnaz; Nourizadeh, Navid

2014-01-01

183

Hyponatraemia and dehydration in severe malaria.  

PubMed Central

The prevalence and likely cause of hyponatraemia in severe childhood malaria were investigated. One hundred and thirty two children, 47 of whom had cerebral malaria, were prospectively recruited and serial simple indices of fluid and electrolyte balance and renal function monitored during admission. In 55%, hyponatraemia (sodium < 135 mmol/l) was present on admission. Hyponatraemia was pronounced (sodium < or = 130 mmol/l) in 21%, and these children gained less weight during admission (mean weight gain 2.4% v 4.3%) than children with a normal sodium (135-145 mmol/l). Overall, 31% of survivors were at least moderately dehydrated on admission (5% weight gain by discharge). These children had higher plasma urea concentrations on admission (6.1 v 4.5 mmol/l) and were more acidotic (mean base excess -12.1 v -8.0) than children who were not dehydrated. There were changes in simple indices of renal function between admission and discharge in children who survived (creatinine 65.7 v 37.9 mumol/l and urea 5.5 v 1.9 mmol/l). The results suggest that dehydration is common in severe childhood malaria, that it may contribute to mild impairment in renal function, and that hyponatraemic children are less water depleted, showing appropriate rather than inappropriate secretion of antidiuretic hormone. PMID:8787422

English, M C; Waruiru, C; Lightowler, C; Murphy, S A; Kirigha, G; Marsh, K

1996-01-01

184

Basic Study on Sludge Concentration and Dehydration with Ultrasonic Exposure  

NASA Astrophysics Data System (ADS)

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.

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

2005-06-01

185

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

SciTech Connect

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.

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

186

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

PubMed

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

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

2015-03-01

187

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

Microsoft Academic Search

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

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

1979-01-01

188

Powder X-ray thermodiffraction study of mirabilite and epsomite dehydration. Effects of direct IR-irradiation on samples.  

PubMed

This paper investigates the thermal and irradiation-dependent dehydration and kinetics occurring in Na2SO4.10H2O (mirabilite) and MgSO4.7H2O (epsomite) at room conditions by using powder X-ray thermodiffraction. An improved version of a first optically stimulated X-ray diffractometer prototype was used. Specific software for the thermodiffraction study was developed (XPowder PLUS) and a filter inserted between the lamp (heating system) and the sample. The results show that these salts are thermal and irradiation sensitive. The temperature and kinetic rates of the salt conversions differed depending on direct exposure to high-intensity radiation (photodehydration) or whether the radiation was blocked by the filter (thermodehydration). In general, radiation-induced dehydration triggers the transformation at lower temperature and accelerates the kinetic reaction more than when the filter is used. Mirabilite dehydration starts with the initial radiation impacts, unlike epsomite. Thermodehydration and photodehydration of mirabilite is a non-isothermal reaction occurring through an amorphous-mediated step. Radiation damage in epsomite leads to isothermal dehydration, whereas non-isothermal dehydration occurs when epsomite is thermally damaged. In both cases, no amorphous material was observed. Because of the weaker bond between cation and oxygen atom in mirabilite, its thermal and radiation stability is lower than in epsomite. These results have important implications for the prevention of salt weathering of porous materials found in the cultural heritage. PMID:17500533

Cardell, Carolina; Sánchez-Navas, Antonio; Olmo-Reyes, F José; Martín-Ramos, J Daniel

2007-06-15

189

Condensation polyimides  

NASA Technical Reports Server (NTRS)

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.

Hergenrother, P. M.

1989-01-01

190

Continuous detonation reaction engine  

NASA Technical Reports Server (NTRS)

Reaction engine operates on the principles of a controlled condensed detonation rather than on the principles of gas expansion. The detonation results in reaction products that are expelled at a much higher velocity.

Lange, O. H.; Stein, R. J.; Tubbs, H. E.

1968-01-01

191

Voluntary dehydration and alliesthesia for water.  

PubMed

The purpose of this experiment was to explore the complex relationship between fluid consumption and consumption factors (thirst, voluntary dehydration, water alliesthesia, palatability, work-rest cycle) during a simulated 14.5-km desert walk (treadmill, 1.34 m X s-1, 5% grade, 40 degrees C dry bulb/26 degrees C wet bulb, and wind speed of approximately 1.2 m X s-1). Twenty-nine subjects were tested (30 min X h-1, 6 h) on each of two nonconsecutive days. The subjects were randomly assigned to one of three groups: tap water (n = 8), iodine-treated tap water (n = 11), or iodine-treated flavored tap water (n = 10). The temperature of the water was 40 degrees C during one trial and 15 degrees C on the other. Mean sweat losses (6 h) varied between 1.4 kg (warm iodine-treated; 232 +/- 44 g X h-1) and 3.0 kg (cool iodine-treated flavored; 509 +/- 50 g X h-1). Warm drinks were consumed at a lower rate than cool drinks (negative and positive alliesthesia). This decreased consumption resulted in the highest percent body weight losses (2.8 and 3.2%). Cooling and flavoring effects on consumption were additive and increased the rate of intake by 120%. The apparent paradox between reduced consumption concomitant with severe dehydration and hyperthermia is attributed to negative alliesthesia for warm water rather than an apparent inadequacy of the thirst mechanism. The reluctance to drink warm iodine-treated water resulted in significant hyperthermia, dehydration, hypovolemia, and, in two cases, heat illness. PMID:6490470

Hubbard, R W; Sandick, B L; Matthew, W T; Francesconi, R P; Sampson, J B; Durkot, M J; Maller, O; Engell, D B

1984-09-01

192

Dehydration of plutonium or neptunium trichloride hydrate  

DOEpatents

A process is described for 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.

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

1992-03-24

193

Peripheral gangrene in hypernatraemic dehydration of infancy.  

PubMed Central

Gangrene of the extremities complicating diarrhoea and severe hypernatraemic dehydration occurred in 6 infants. This is a rare complication of gastroenteritis, and its association with hypernatraemia does not seem to have previously been emphasized. The increased blood viscosity resulting from serum hyperosmolarity may have been responsible for the gangrene, and studies in our patients suggested that disseminated intravascular coagulation was present. In addition to fluid and electrolyte replacement, the infants were treated with heparin with some recovery of the affected extremities. Images FIG. 1 FIG. 2 FIG. 3 PMID:1200677

Comay, S C; Karabus, C D

1975-01-01

194

Dehydration of plutonium or neptunium trichloride hydrate  

DOEpatents

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.

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

1992-01-01

195

Effects of Dehydration on Fish Muscles at Chilled Temperature  

NASA Astrophysics Data System (ADS)

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.

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

196

Olfactory contributions to dehydration-induced anorexia in weanling rats.  

PubMed

By 20 days of age, dehydration produces a clear anorexia, even though weanling rats have had only limited feeding and drinking experience. Their lack of ingestive experience makes weanlings good subjects for studying the physiological mechanisms subserving anorexic phenomena because learned contributions are unlikely to add significant complications. Twenty-day-old rats dehydrated by hypertonic saline injection were anorexic when offered milk or solid food (rat chow), but not when offered sucrose solutions (Experiment I). However, when the scent of almond was associated with sucrose solutions, or with water, intake of these solutions was depressed by dehydration (Experiment II). Thus for dehydrated rats, olfactory stimulation may help produce dehydration-induced anorexia. Making rats anosmic by intransal lavage with ZnSO4 (Experiment III) eliminated the anorexia to almond-scented water and partially eliminated that to milk. For these fluids, an odor cue seems a requirement for the occurrence of dehydration-anorexia. In Experiment IV, we found that dehydration-anorexia did not occur when milk was infused directly into pups' mouths. This finding suggests that the inhibitory process mediating dehydration-anorexia influences the approach to food and not the actual consumatory response that occurs once food is in the mouth. The inhibition of feeding produced by dehydration, therefore, may depend largely on olfactory cues, and seems to operate at a distance, as rats locate and approach food. PMID:7152117

Bruno, J P; Hall, W G

1982-11-01

197

Dehydration softening of serpentine and its roles in the intermediate-depth earthquakes  

NASA Astrophysics Data System (ADS)

A popular hypothesis for the occurrence of double seismic zones in subducting slabs, located at the depth of about 50-200 km, is dehydration embrittlement of serpentinized mantle. Brittle failure of serpentinite has been attributed to excess pore fluid pressure caused by dehydration reaction (Raleigh and Paterson, 1965, JGR; Murrell and Ismail, 1976, Tectonophysics). However, in previous deformation experiments of serpentinites and other hydrous minerals using gas-medium apparatus, confining pressure was limited to 500 MPa, which corresponds to the depth of the middle crust (~15 km). It is questionable if the same mechanism could be effective in subducting slabs at higher pressures. We conducted constant strain-rate experiments of a serpentinite sample, which consists of almost pure antigorite, using solid-medium deformation apparatus. Cylindrical specimens of serpentinite with the diameter of 10 mm and the length of 15 mm were cut from the serpentinite sample and jacketed in Ag tubes. Deformation experiments were conducted at 500 oC and 700 oC under the confining pressure of 800 MPa. The temperature of the dehydration reaction is about 650 oC at this pressure. The strain rate ranges from 3.3x10-5 to 2x10-4 sec-1. At 500 oC, antigorite was very hard and not yielded even after differential stress exceeded 900 MPa. The samples deformed at 700 oC without pre-heating exhibited brittle failures and strain hardening. Dehydration reaction had not occurred in these samples. On the contrary, samples deformed at 700 oC after static heating exhibited steady creep behaviors. The yield strength of preheated samples were 200-280 MPa. The differential stress was slightly increased when the sample strain exceeds 5%. Velocity step tests indicated that the yield stress is insensitive to the strain rate. In the pre-heated samples, intergranular pores were developed. No cracks nor microfaults were observed after deformation experiments. The color of antigorite changed from dark green to pink, possibly due to highly oxidized atmosphere caused by free water release. Reaction products of olivine (forsterite) exhibited host-controlled weak lattice preferred orientation (LPO) but there was no evidence for intracrystalline slip. Mechanical behaviors and microstructural features both indicated that the dominant deformation mechanism of pre-heated samples was cataclastic flow of reaction products. Significant volume loss in these samples suggests compaction and escape of water during deformation experiments. Strain localization in the serpentinized parts of mantle due to dehydration softening and high fluid pressure caused by pore collapse would trigger earthquakes in surrounding peridotite mantle.

Shimizu, I.; Watanabe, Y.; Michibayashi, K.

2010-12-01

198

Dropwise condensation  

PubMed Central

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

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

2008-01-01

199

Dehydration-melting of amphibolite at 10 kbar: the effects of temperature and time  

Microsoft Academic Search

We have simulated the dehydration-melting of a natural, low-K, calcic amphibolite (67.4% hornblende, 32.5% anorthite) in piston-cylinder experiments at 10 kbar and 750–1000°C, for 1–9 days. The solidus temperature is lower than 750°C; garnet appears at 850°C. The overall reaction is: Hb+P?L+Cpx+Al-Hb+Ca-Hb+Ga+Opx. Three stages of reaction are: (1) melting dominated by the growth of clinopyroxene and garnet, with little change

Michael B. Wolf; Peter J. Wyllie

1994-01-01

200

Treatment of dredged sludge by mechanical dehydration  

SciTech Connect

Sludge deposits in the water area damage the ecosystems and environments; their elimination has always been an urgent task for human communities. Generally, sludge deposits are dredged out of the bottom of the water area, transported to, and discharged at a large disposal area on land. Recently, however, it has become increasingly difficult to secure disposal areas and routes of speedy transportation for disposal of dredged sludge. Accordingly, there is an urgent need to reduce both the volume of dredged sludge and the size of the disposal area. This mechanical method is different from the conventional engineering dehydration by loading, consolidation, and drainage in that the dredged sludge is separated into sludge cakes and clean water that can be returned to the water area through mechanical centrifugal dehydration. Sludge deposits are distributed thin and wide on the bottom of the water area, and a pump dredge has been proved effective in many cases for dredging the upper layers of sludge deposits accurately and without creating turbidity in water. This mechanical sludge treatment technique can be most efficient when used in combination with a pump dredge. This method offers the following advantages: (a) It requires smaller space for treatment and disposal of dredged sludge than the conventional method. (b) Facilities and costs for transportation can be reduced. (c) Various systems can be adopted for transportation of sludge cakes. (d) This system is transportable and compact and can be constructed anywhere either on land or on water.

Maekawa, T.

1992-03-01

201

Inorganic compounds for passive solar energy storage: Solid-state dehydration materials and high specific heat materials  

NASA Astrophysics Data System (ADS)

Two classes of hydrated inorganic salts have been studied to assess their potential as materials for passive solar energy storage. The materials are part of the quaternary system CaO-Al2O3-SO3-H2O and related chemical systems, and the two classes are typified by ettringite, a trisubstituted salt, and Friedel's salt, a monosubstituted salt. The trisubstituted salts were studied for their possible application in latent heat storage, utilizing a low-temperature dehydration reaction, and both classes were studies for their application in sensible heat storage. In order to assess their potential for energy storage, the salts have been synthesized, characterized by several analytical techniques, and thermal properties measured. The dehydration data of that the trisubstituted salts vary somewhat with chemical composition, with the temperature of the onset of dehydration ranging from 6(0)C to 33(0)C, and enthalpy changes on dehydration ranging from 60 to 200 cal/g. Heat capacity is less variable with composition; values for the trisubstituted phases are 30 cal/g/(0)C and for the monosubstituted phases between 0.23 and 0.28 cal/g/(0)C. Preliminary experiments indicate that the dehydration is reversible, and suggest that the materials might have additional potential as solar desiccant materials. These thermal data demonstrate the trisubstituted salts have potential as latent heat storage materials, and that both classes of salts have potential as sensible heat storage materials.

Struble, L. J.; Brown, P. W.

1986-04-01

202

J. Phys. Chem. 1989, 93, 1267-1272 1267 Photoinduced Harpoon Reactions as a Probe of Condensed-Phase Dynamics: IC1 in  

E-print Network

-Phase Dynamics: IC1 in Liquid and Solid Xenon F. Okada? L. Wiedeman, and V. A. Apkarian* Department of Chemistry-photon-induced harpoon reactions of IC1 in liquid and solid xenon are reported. The reaction dynamics is followed scheme for liquid-phase rare-gas halide exciplex lasers! The studies of IC1in both liquid and solid xenon

Apkarian, V. Ara

203

Osmotic dehydration of pineapple: kinetics and product quality  

Microsoft Academic Search

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

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

1996-01-01

204

OSMOTIC DEHYDRATION OF FOODS: MASS TRANSFER AND MODELING ASPECTS  

Microsoft Academic Search

Biological materials contain a variety of individual soluble components. When cellular biological materials are immersed in osmotic solution, multicomponent mass transfer occurs, which ultimately leads to the loss of water from the food, or osmotic dehydration. Mass transfer of food constituents during osmotic dehydration may cause changes in food quality in terms of nutritional value, texture, color, and taste. The

John Shi; Marc Le Maguer

2002-01-01

205

Geothermal vegetable dehydration at Brady`s Hot Springs, Nevada  

Microsoft Academic Search

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

1994-01-01

206

Dehydration of serpentinized slab mantle: Seismic evidence from southwest Japan  

Microsoft Academic Search

The seismicity in the subducting Philippine Sea slab (PHS) beneath southwest Japan shows a variety of modes of occurrence. We try to explain this variety on the basis of dehydration embrittlement in the subducting oceanic crust and\\/or mantle. The PHS subducting along the Nankai Trough shows commonly a single narrow seismic zone shallower than 60 km, which may reflect dehydration

Tetsuzo Seno; Dapeng Zhao; Yoji Kobayashi; Masao Nakamura

2001-01-01

207

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...

208

Dehydration and crystallization kinetics of zirconia-yttria gels  

Microsoft Academic Search

Zirconia and zirconia-yttria gels containing 4 and 8 mol% yttria were obtained by coprecipitation and drying at 373 K. The dehydration and crystallization behavior of the dried gels was studied by DSC, TG, and XRD. The gels undergo elimination of water over a wide temperature range of 373--673 K. The peak temperature of the endotherm corresponding to dehydration and the

S. Ramanathan; R. V. Muraleedharan; S. K. Roy; P. K. K. Nayar

1995-01-01

209

Retention of nutrients in green leafy vegetables on dehydration.  

PubMed

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

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

2013-10-01

210

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

Code of Federal Regulations, 2010 CFR

...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...

2010-07-01

211

Qualitative and quantitative characterization of thein vitro dehydration process of hydrogel contact lenses  

Microsoft Academic Search

Purpose: To investigate the in vitro dehydration process of conventional hydrogel and silicone-hydrogel contact lens materials. Methods: Eight conventional hydrogel and five silicone-hydrogel contact lenses were dehydrated under controlled environmental conditions on an analytical balance. Data were taken at 1-min intervals and dehydration curves of cumulative dehydration (CD), valid dehydration (VD), and dehydration rate (DR) were obtained. Several quantitative descriptors

José M. González-Méijome; Antonio López-Alemany; José B. Almeida; Manuel A. Parafita; Miguel F. Refojo

2007-01-01

212

Polariton condensates  

SciTech Connect

Most students of physics know about the special properties of Bose-Einstein condensates (BECs) as demonstrated in the two best-known examples: superfluid helium-4, first reported in 1938, and condensates of trapped atomic gases, first observed in 1995. (See the article by Wolfgang Ketterle in PHYSICS TODAY, December 1999, page 30.) Many also know that superfluid {sup 3}He and superconducting metals contain BECs of fermion pairs. An underlying principle of all those condensed-matter systems, known as quantum fluids, is that an even number of fermions with half-integer spin can be combined to make a composite boson with integer spin. Such composite bosons, like all bosons, have the property that below some critical temperature--roughly the temperature at which the thermal de Broglie wavelength becomes comparable to the distance between the bosons--the total free energy is minimized by having a macroscopic number of bosons enter a single quantum state and form a macroscopic, coherent matter wave. Remarkably, the effect of interparticle repulsion is to lead to quantum mechanical exchange interactions that make that state robust, since the exchange interactions add coherently.

Snoke, David; Littlewood, Peter [University of Pittsburgh, Pennsylvania (United States); University of Cambridge (United Kingdom)

2010-08-15

213

Two-stage dehydration of sugars  

DOEpatents

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.

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

2009-11-10

214

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)

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.

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

2006-02-01

215

Transient dehydration of lungs in tail-suspended rats  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

216

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

PubMed Central

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

2014-01-01

217

Tandem mechanisms facilitate dehydration of crude  

SciTech Connect

In tandem, electrostatic and mechanical coalescence mechanisms can dehydrate oil at higher loading rates and/or lower temperatures than either mechanism acting alone. One of the most effective methods for removing entrained (emulsified) water from crude oil involves the use of high-voltage electric fields. Under the influence of an electric field, water droplets dispersed in the oil become polarized (i.e., acquire a net charge). Attractive electrostatic forces between droplets which have acquired opposite charges promote coalescence and, therefore, more rapid gravitation of the aqueous phase from the mixture. The mechanisms of electrostatically enhanced coalescence have been reviewed elsewhere. Both ac and dc electric fields are commonly used in oil field coalescers and a comparison of the relative merits of these two systems and a discussion of the effects of electrode configuration on coalescence are available in the literature. In a high-voltage electric field, water droplets in oil are subjected to hydrodynamic and electrical stresses which can lead to droplet dispersal in competition with electrostatically induced coalescence. These stresses become more severe and are more likely to cause dispersal with increasing droplet diameter and increasing electric field strength. Therefore, electrical and hydrodynamic stresses tend to limit the maximum size of droplets which can exist in the field.

Sublette, K.L.; Johnson, B.

1986-05-19

218

Effects of dehydration on performance in man: Annotated bibliography  

NASA Technical Reports Server (NTRS)

A compilation of studies on the effect of dehydration on human performance and related physiological mechanisms. The annotations are listed in alphabetical order by first author and cover material through June 1973.

Greenleaf, J. E.

1973-01-01

219

Experimental apparatus for simultaneous dehydration and sweetening of natural gas  

E-print Network

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...

Pace, Christopher Lee

1997-01-01

220

Instrument for Determining Depth of Dehydration of Frozen Fish  

E-print Network

Instrument for Determining Depth of Dehydration of Frozen Fish JOHN G. CALLAN and JOHN J. RYAN of a hand-operated wood John G. Callan is a Supervisory Mechanical Engineer and John J. Ryan is a Research

221

NOVEL POLYMERIC MEMBRANE FOR DEHYDRATION OF ORGANIC SOLVENTS  

EPA Science Inventory

Pervaporation has emerged as an economically viable alternative technology for dehydration of organic solvents, removal of organic compounds and organic/organic separations. Development of a membrane system with suitable flux and selectivity characteristics plays a critical role...

222

Dehydration and crystallization kinetics of zirconia-yttria gels  

SciTech Connect

Zirconia and zirconia-yttria gels containing 4 and 8 mol% yttria were obtained by coprecipitation and drying at 373 K. The dehydration and crystallization behavior of the dried gels was studied by DSC, TG, and XRD. The gels undergo elimination of water over a wide temperature range of 373--673 K. The peak temperature of the endotherm corresponding to dehydration and the kinetic constants for the process were not influenced by the yttria content of the gel. The enthalpy of dehydration observed was in good agreement with the heat of vaporization data. The dehydration was followed by a sharp exothermic crystallization process. The peak temperature of the exotherm and the activation energy of the process increased with an increase in yttria content, while the enthalpy of crystallization showed a decrease. The ``glow effect`` reduced with increasing yttria content. Pure zirconia crystallizes in the tetragonal form while the zirconia containing 4 and 8 mol% yttria appears to crystallize in the cubic form.

Ramanathan, S.; Muraleedharan, R.V.; Roy, S.K.; Nayar, P.K.K. [Bhabha Atomic Research Centre, Bombay (India). Metallurgy Division

1995-02-01

223

Understanding Condensation  

NSDL National Science Digital Library

Monica Hartman, Assistant Director for Science in St. Clair County, Michigan, conducted this research while she was the learning specialist in a small suburban district just outside a large Midwestern city. While teaching full time in this district she was also completing her doctoral program in education at the University of Michigan. In this chapter, she tells the story of a "science talk" about condensation among fifth graders. She acted as a source and facilitator of change as she and the fifth-grade teacher worked collaboratively to help students share responsibility for their own learning. She describes their continual assessment of student understanding that occurred as their students struggled to explain observations and as they, the teachers, carefully resisted the temptation to end the struggle by saying "that's right!"

Monica Hartman

2007-12-01

224

Retention of nutrients in green leafy vegetables on dehydration  

Microsoft Academic Search

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.\\u000a The fresh and dehydrated samples were analyzed for selected proximate constituents,

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

225

Age, dehydration and fatigue crack growth in dentin  

Microsoft Academic Search

A preliminary study of the effects from age and dehydration on fatigue crack growth in human dentin was conducted. Compact tension (CT) fatigue specimens of coronal dentin were prepared from extracted molars and subjected to high cycle fatigue (105dehydrated dentin (mean

Devendra Bajaj; Naryana Sundaram; Ahmad Nazari; D. Arola

2006-01-01

226

Impact of dehydration on a full body resistance exercise protocol  

Microsoft Academic Search

This study examined effects of dehydration on a full body resistance exercise workout. Ten males completed two trials: heat\\u000a exposed (with 100% fluid replacement) (HE) and dehydration (~3% body mass loss with no fluid replacement) (DEHY) achieved\\u000a via hot water bath (~39°C). Following HE and DEHY, participants performed three sets to failure (using predetermined 12 repetition\\u000a maximum) of bench press,

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

2010-01-01

227

External Validation and Comparison of Three Pediatric Clinical Dehydration Scales  

PubMed Central

Objective To prospectively validate three popular clinical dehydration scales and overall physician gestalt in children with vomiting or diarrhea relative to the criterion standard of percent weight change with rehydration. Methods We prospectively enrolled a non-consecutive cohort of children ? 18 years of age with an acute episode of diarrhea or vomiting. Patient weight, clinical scale variables and physician clinical impression, or gestalt, were recorded before and after fluid resuscitation in the emergency department and upon hospital discharge. The percent weight change from presentation to discharge was used to calculate the degree of dehydration, with a weight change of ? 5% considered significant dehydration. Receiver operating characteristics (ROC) curves were constructed for each of the three clinical scales and physician gestalt. Sensitivity and specificity were calculated based on the best cut-points of the ROC curve. Results We approached 209 patients, and of those, 148 were enrolled and 113 patients had complete data for analysis. Of these, 10.6% had significant dehydration based on our criterion standard. The Clinical Dehydration Scale (CDS) and Gorelick scales both had an area under the ROC curve (AUC) statistically different from the reference line with AUCs of 0.72 (95% CI 0.60, 0.84) and 0.71 (95% CI 0.57, 0.85) respectively. The World Health Organization (WHO) scale and physician gestalt had AUCs of 0.61 (95% CI 0.45, 0.77) and 0.61 (0.44, 0.78) respectively, which were not statistically significant. Conclusion The Gorelick scale and Clinical Dehydration Scale were fair predictors of dehydration in children with diarrhea or vomiting. The World Health Organization scale and physician gestalt were not helpful predictors of dehydration in our cohort. PMID:24788134

Jauregui, Joshua; Nelson, Daniel; Choo, Esther; Stearns, Branden; Levine, Adam C.; Liebmann, Otto; Shah, Sachita P.

2014-01-01

228

Whole transcriptome organisation in the dehydrated supraoptic nucleus  

PubMed Central

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

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

2013-01-01

229

Low Energy Nuclear Reactions: 2007 Update  

Microsoft Academic Search

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

Steven B. Krivit

2007-01-01

230

Arctic stratospheric dehydration - Part 2: Microphysical modeling  

NASA Astrophysics Data System (ADS)

Large areas of synoptic-scale ice PSCs (polar stratospheric clouds) distinguished the Arctic winter 2009/2010 from other years and revealed unprecedented evidence of water redistribution in the stratosphere. A unique snapshot of water vapor repartitioning into ice particles was obtained under extremely cold Arctic conditions with temperatures around 183 K. Balloon-borne, aircraft and satellite-based measurements suggest that synoptic-scale ice PSCs and concurrent reductions and enhancements in water vapor are tightly linked with the observed de- and rehydration signatures, respectively. In a companion paper (Part 1), water vapor and aerosol backscatter measurements from the RECONCILE (Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions) and LAPBIAT-II (Lapland Atmosphere-Biosphere Facility) field campaigns have been analyzed in detail. This paper uses a column version of the Zurich Optical and Microphysical box Model (ZOMM) including newly developed NAT (nitric acid trihydrate) and ice nucleation parameterizations. Particle sedimentation is calculated in order to simulate the vertical redistribution of chemical species such as water and nitric acid. Despite limitations given by wind shear and uncertainties in the initial water vapor profile, the column modeling unequivocally shows that (1) accounting for small-scale temperature fluctuations along the trajectories is essential in order to reach agreement between simulated optical cloud properties and observations, and (2) the use of recently developed heterogeneous ice nucleation parameterizations allows the reproduction of the observed signatures of de- and rehydration. Conversely, the vertical redistribution of water measured cannot be explained in terms of homogeneous nucleation of ice clouds, whose particle radii remain too small to cause significant dehydration.

Engel, I.; Luo, B. P.; Khaykin, S. M.; Wienhold, F. G.; Vömel, H.; Kivi, R.; Hoyle, C. R.; Grooß, J.-U.; Pitts, M. C.; Peter, T.

2014-04-01

231

The functional architecture of dehydration-anorexia.  

PubMed

The anorexia that accompanies the drinking of hypertonic saline (DE-anorexia) is a critical adaptive behavioral mechanism that helps protect the integrity of fluid compartments during extended periods of cellular dehydration. Feeding is rapidly reinstated once drinking water is made available again. The relative simplicity and reproducibility of these behaviors makes DE-anorexia a very useful model for investigating how the various neural networks that control ingestive behaviors first suppress and then reinstate feeding. We show that DE-anorexia develops primarily because the mechanisms that terminate ongoing meals are upregulated in such a way as to significantly reduce meal size. At the same time however, signals generated by the ensuing negative energy balance appropriately activate neural mechanisms that can increase food intake. But as the output from these two competing processes is integrated, the net result is an increasing reduction of nocturnal food intake, despite the fact that spontaneous meals are initiated with the same frequency as in control animals. Furthermore, hypothalamic NPY injections also stimulate feeding in DE-anorexic animals with the same latency as controls, but again meals are prematurely terminated. Comparing Fos expression patterns across the brain following 2-deoxyglucose administration to control and DE-anorexic animals implicates neurons in the descending part of the parvicellular paraventricular nucleus of the hypothalamus and the lateral hypothalamic areas as key components of the networks that control DE-anorexia. Finally, DE-anorexia generates multiple inhibitory processes to suppress feeding. These are differentially disengaged once drinking water is reinstated. The paper represents an invited review by a symposium, award winner or keynote speaker at the Society for the Study of Ingestive Behavior [SSIB] Annual Meeting in Portland, July 2009. PMID:20399797

Watts, Alan G; Boyle, Christina N

2010-07-14

232

A model of teneral dehydration in Glossina.  

PubMed

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

Childs, S J

2014-03-01

233

THE FUNCTIONAL ARCHITECTURE OF DEHYDRATION-ANOREXIA  

PubMed Central

The anorexia that accompanies the drinking of hypertonic saline (DE-anorexia) is a critical adaptive behavioral mechanism that helps protect the integrity of fluid compartments during extended periods of cellular dehydration. Feeding is rapidly reinstated once drinking water is made available again. The relative simplicity and reproducibility of these behaviors makes DE-anorexia a very useful model for investigating how the various neural networks that control ingestive behaviors first suppress and then reinstate feeding. We show that DE-anorexia develops primarily because the mechanisms that terminate ongoing meals are upregulated in such a way as to significantly reduce meal size. At the same time however, signals generated by the ensuing negative energy balance appropriately activate neural mechanisms that can increase food intake. But as the output from these two competing processes is integrated, the net result is an increasing reduction of nocturnal food intake, despite the fact that spontaneous meals are initiated with the same frequency as in control animals. Furthermore, hypothalamic NPY injections also stimulate feeding in DE-anorexic animals with the same latency as controls, but again meals are prematurely terminated. Comparing Fos expression patterns across the brain following 2-deoxyglucose administration to control and DE-anorexic animals implicates neurons in the descending part of the parvicellular paraventricular nucleus of the hypothalamus and the lateral hypothalamic areas as key components of the networks that control DE-anorexia. Finally, DE-anorexia generates multiple inhibitory processes to suppress feeding. These are differentially disengaged once drinking water is reinstated. PMID:20399797

Watts, Alan G.; Boyle, Christina N.

2010-01-01

234

Enantioselective dehydration of butan-2-ol using zeolite Y modified with dithiane oxides  

SciTech Connect

Modification of zeolite H-Y by dithiane oxides (2-R-1,3-dithiane 1-oxide; R = H, CH{sub 3}, C{sub 6}H{sub 5}) is shown to enhance significantly its activity for the acid catalyzed gas phase dehydration of butan-2-ol. The rate enhancement is observed for catalysts that are prepared by adding the dithiane oxide to the zeolite synthesis gel or by adsorption of the dithiane oxide onto commercial samples of zeolite H-Y. The origin of the rate enhancement is considered to result from a specific interaction between the dithiane oxide modifier with both the extra-framework and framework aluminum in the zeolite. Modification of zeolite H-Y with (R)-1,3-dithiane 1-oxide enhances the conversion of (S)-butan-2-ol compared to (R)-butan-2-ol in the temperature range 110-150{degrees}C when the two enantiomers are reacted separately. Modification with (S)-2-phenyl-1,3-dithiane 1-oxide gives a catalyst for which (R)-butan-2-ol is the most reactive of the two enantiomers. Reaction of racemic butan-2-ol over these chirally modified H-Y zeolites demonstrates that this modification procedure makes the zeolite enantiomerically discriminating and one enantiomer preferentially reacts, although both are present in the micropores under the reaction conditions. This effect is considered to be due to enantioselective rate enhancement, since, although the rate of dehydration of both enantiomers is enhanced in the chiral environment, the dehydration rate of one enantiomer is accelerated relative to the other. It is suggested that the effect is due to preferential adsorption at the chiral active site. 34 refs., 7 figs., 6 tabs.

Feast, S.; Siddiqui, H.; Bethell, D. [Univ. of Liverpool (United Kingdom)] [and others] [Univ. of Liverpool (United Kingdom); and others

1997-04-15

235

Dehydration of Methylcyclohexanol Isomers in the Undergraduate Organic Laboratory and Product Analysis by Gas Chromatography-Mass Spectroscopy (GC-MS)  

ERIC Educational Resources Information Center

Dehydrations of "cis"- and "trans"-2-methylcyclohexanol mixtures were carried out with 60% sulfuric acid at 78-80 [degrees]C as a function of time and the products were identified by gas chromatography-mass spectroscopy (GC-MS) analysis. The compounds identified in the reaction mixtures include alkenes, 1-, 3-, and 4-methylcyclohexenes and…

Clennan, Malgorzata M.; Clennan, Edward L.

2011-01-01

236

Brønsted instead of Lewis acidity in functionalized MIL-101Cr MOFs for efficient heterogeneous (nano-MOF) catalysis in the condensation reaction of aldehydes with alcohols.  

PubMed

Porous chromium(III) 2-nitro-, 2-amino-, and nonfunctionalized terephthalate (MIL-101Cr) metal organic frameworks are heterogeneous catalysts for diacetal formation from benzaldehyde and methanol (B-M reaction) as well as other aldehydes and alcohols. MIL-101Cr-NO2 obtained by direct reaction between CrO3 and 2-nitro-terephthalate showed the highest activity with 99% conversion in the B-M reaction in 90 min and turnover numbers of 114. The activity decreased in the order MIL-101Cr-NO2 > MIL-101Cr > MIL-101Cr-NH2. Within different samples of nonfunctionalized MIL-101Cr the activity increased with surface area. Methanol gas sorption of the different MIL materials correlates with the BET surface area and pore volume but not with the diacetalization activity. Benzaldehyde adsorption from heptane showed no significant difference for the different MILs. Gas sorption studies of CD3CN to probe for a higher Lewis acidity in MIL-101Cr-NO2 remained inconclusive. A high B-M catalytic activity of wet MIL-101Cr-NO2 excluded significant contributions from coordinatively unsaturated Lewis-acid sites. pH measurements of methanol dispersions of the MIL materials gave the most acidic pH (as low as 1.9) for MIL-101Cr-NO2, which significantly increased over MIL-101Cr (3.0) to MIL-101Cr-NH2 (3.3). The increase in acidity is of short range or a surface effect to the heterogeneous MIL particles as protons dissociating from the polarized aqua ligands (Cr-OH2) have to stay near the insoluble counteranionic framework. The variation in Brønsted acidity of MIL-101Cr-NO2 > MIL-101Cr ? MIL-101Cr-NH2 correlates with the withdrawing effect of NO2 and the diacetalization activity. The catalytic B-M activity of soluble, substitution-inert, and acidic Cr(NO3)3·9H2O supports the Brønsted-acid effect of the MIL materials. Filtration and centrifugation experiments with MIL-101Cr-NO2 revealed that about 2/3 of the catalytic activity comes from nano-MOF particles with a diameter below 200 nm. The MIL-101Cr-NO2 catalysts can be recycled five times with very little loss in activity. The diacetalization activity of MIL-101Cr-NO2 decreases with the alcohol chain length from methanol over ethanol, n-propanol, n-butanol, to almost inactive n-pentanol, while conversions for benzaldehyde, paratolylaldehyde, 4-chlorobenzaldehyde, and cyclohexanone all reach 90% or more after 90 min. PMID:25006999

Herbst, Annika; Khutia, Anupam; Janiak, Christoph

2014-07-21

237

Condensation model for the ESBWR passive condensers  

SciTech Connect

In the General Electric's Economic simplified boiling water reactor (GE-ESBWR) the passive containment cooling system (PCCS) plays a major role in containment pressure control in case of an loss of coolant accident. The PCCS condenser must be able to remove sufficient energy from the reactor containment to prevent containment from exceeding its design pressure following a design basis accident. There are three PCCS condensation modes depending on the containment pressurization due to coolant discharge; complete condensation, cyclic venting and flow through mode. The present work reviews the models and presents model predictive capability along with comparison with existing data from separate effects test. The condensation models in thermal hydraulics code RELAP5 are also assessed to examine its application to various flow modes of condensation. The default model in the code predicts complete condensation well, and basically is Nusselt solution. The UCB model predicts through flow well. None of condensation model in RELAP5 predict complete condensation, cyclic venting, and through flow condensation consistently. New condensation correlations are given that accurately predict all three modes of PCCS condensation. (authors)

Revankar, S. T. [Pohang Univ. of Science and Technology, 400 Central Drive, West Lafayette, IN 47906 (United States); Zhou, W.; Wolf, B.; Oh, S. [Purdue Univ., West Lafayette, IN 47906 (United States)

2012-07-01

238

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

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

239

In situ FTIR study on the dehydration of natural goethite  

NASA Astrophysics Data System (ADS)

Fourier Transform Infrared (FTIR) spectroscopy, thermal analysis -Differential Scanning Calorimetry (DSC) and Thermo-Gravimetry (TG-DTG) were used to study the dehydration behavior of synthetic goethite and two naturally occurring goethite samples (Natural 1 and Natural 2) from Banded Iron Formation (BIF), at C.S. Halli, Chitradurg district, Karnataka, India. Goethites and its dehydration products were also identified by powder X-ray Diffraction (XRD) method. The dehydration temperatures were at 538, 567 and 578 K for synthetic, Natural 1 and 2 goethite, respectively. On approaching the dehydration temperature, infrared active modes of the hydroxyl groups have shown distinct variations. The peak position for the stretching mode around 3150 cm -1 was shifted upwards, while that for in-plane- deformation mode around 890 cm -1 was down shifted indicating weakening of strength of the hydrogen bonding. No intermediate phase, so called hydro-hematite, was observed in these studies. The total absorbance (area under the peak) of these modes have shown the Arrehenius type behavior in the temperature range 500-600 K, using which the activation energy for the dehydration process was estimated as 71, 103 and 85 kJ/mol for synthetic, Natural 1 and 2 goethites respectively.

Prasad, P. S. R.; Shiva Prasad, K.; Krishna Chaitanya, V.; Babu, E. V. S. S. K.; Sreedhar, B.; Ramana Murthy, S.

2006-09-01

240

Luminescence induced by dehydration of kaolin - Association with electron-spin-active centers and with surface activity for dehydration-polymerization of glycine  

NASA Technical Reports Server (NTRS)

Experimental data concerning emission of light upon dehydration as a function of preheating and pre-gamma-irradiation are correlated with reported studies of electron-spin resonance (ESR) activity after similar pretreatments. The effect of these pretreatments on the kaolin-promoted incorporation of glycine into peptide oligomers in a wet/cold, hot/dry fluctuating environment is compared to their effect on the ESR and luminescent signals. The existence of spectroscopically active centers appears to be loosely anticorrelated with reaction yield; these yields are increased by increasing the overall energy content of the material. It is concluded that some part of the chemical yield is produced by a mechanism involving intrinsic, excited electronic states of the clay crystal lattice. These states may be derived from thermally, interfacially, and/or mechanically induced charge reorganization within interspersed energy levels in the band structure of the material.

Coyne, L.; Hovatter, W.; Sweeney, M.

1983-01-01

241

Isothermal dehydration of thin films of water and sugar solutions  

NASA Astrophysics Data System (ADS)

The process of quasi-isothermal dehydration of thin films of pure water and aqueous sugar solutions is investigated with a dual experimental and theoretical approach. A nanoporous paper disk with a homogeneous internal structure was used as a substrate. This experimental set-up makes it possible to gather thermodynamic data under well-defined conditions, develop a numerical model, and extract needed information about the dehydration process, in particular the water activity. It is found that the temperature evolution of the pure water film is not strictly isothermal during the drying process, possibly due to the influence of water diffusion through the cellulose web of the substrate. The role of sugar is clearly detectable and its influence on the dehydration process can be identified. At the end of the drying process, trehalose molecules slow down the diffusion of water molecules through the substrate in a more pronounced way than do the glucose molecules.

Heyd, R.; Rampino, A.; Bellich, B.; Elisei, E.; Cesàro, A.; Saboungi, M.-L.

2014-03-01

242

Isothermal dehydration of thin films of water and sugar solutions  

SciTech Connect

The process of quasi-isothermal dehydration of thin films of pure water and aqueous sugar solutions is investigated with a dual experimental and theoretical approach. A nanoporous paper disk with a homogeneous internal structure was used as a substrate. This experimental set-up makes it possible to gather thermodynamic data under well-defined conditions, develop a numerical model, and extract needed information about the dehydration process, in particular the water activity. It is found that the temperature evolution of the pure water film is not strictly isothermal during the drying process, possibly due to the influence of water diffusion through the cellulose web of the substrate. The role of sugar is clearly detectable and its influence on the dehydration process can be identified. At the end of the drying process, trehalose molecules slow down the diffusion of water molecules through the substrate in a more pronounced way than do the glucose molecules.

Heyd, R. [Centre de Recherche sur la Matière Divisée, University of Orleans and CNRS, rue de la Férollerie 1B, 45071 Orléans Cedex 2 (France)] [Centre de Recherche sur la Matière Divisée, University of Orleans and CNRS, rue de la Férollerie 1B, 45071 Orléans Cedex 2 (France); Rampino, A. [Centre de Recherche sur la Matière Divisée, University of Orleans and CNRS, rue de la Férollerie 1B, 45071 Orléans Cedex 2 (France) [Centre de Recherche sur la Matière Divisée, University of Orleans and CNRS, rue de la Férollerie 1B, 45071 Orléans Cedex 2 (France); Laboratory of Physical and Macromolecular Chemistry, University of Trieste, Via Giorgieri 1, 34127 Trieste (Italy); Bellich, B.; Elisei, E. [Laboratory of Physical and Macromolecular Chemistry, University of Trieste, Via Giorgieri 1, 34127 Trieste (Italy)] [Laboratory of Physical and Macromolecular Chemistry, University of Trieste, Via Giorgieri 1, 34127 Trieste (Italy); Cesàro, A. [Laboratory of Physical and Macromolecular Chemistry, University of Trieste, Via Giorgieri 1, 34127 Trieste (Italy) [Laboratory of Physical and Macromolecular Chemistry, University of Trieste, Via Giorgieri 1, 34127 Trieste (Italy); Elettra Sincrotrone Trieste, Area Science Park, I-34149 Trieste (Italy); Saboungi, M.-L. [Centre de Recherche sur la Matière Divisée, University of Orleans and CNRS, rue de la Férollerie 1B, 45071 Orléans Cedex 2 (France) [Centre de Recherche sur la Matière Divisée, University of Orleans and CNRS, rue de la Férollerie 1B, 45071 Orléans Cedex 2 (France); Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie (IMPMC), Sorbonne Univ-UPMC, Univ Paris 06, UMR CNRS 7590, Museum National d’Histoire Naturelle, IRD UMR 206, 4 Place Jussieu, F-75005 Paris (France)

2014-03-28

243

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

PubMed

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

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

2014-10-15

244

Effect of experimental and sample factors on dehydration kinetics of mildronate dihydrate: mechanism of dehydration and determination of kinetic parameters.  

PubMed

The dehydration kinetics of mildronate dihydrate [3-(1,1,1-trimethylhydrazin-1-ium-2-yl)propionate dihydrate] was analyzed in isothermal and nonisothermal modes. The particle size, sample preparation and storage, sample weight, nitrogen flow rate, relative humidity, and sample history were varied in order to evaluate the effect of these factors and to more accurately interpret the data obtained from such analysis. It was determined that comparable kinetic parameters can be obtained in both isothermal and nonisothermal mode. However, dehydration activation energy values obtained in nonisothermal mode showed variation with conversion degree because of different rate-limiting step energy at higher temperature. Moreover, carrying out experiments in this mode required consideration of additional experimental complications. Our study of the different sample and experimental factor effect revealed information about changes of the dehydration rate-limiting step energy, variable contribution from different rate limiting steps, as well as clarified the dehydration mechanism. Procedures for convenient and fast determination of dehydration kinetic parameters were offered. PMID:24729295

B?rzi?š, Agris; Acti?š, Andris

2014-06-01

245

Synthesis and Spectroscopic Analysis of a Cyclic Acetal: A Dehydration Performed in Aqueous Solution  

NASA Astrophysics Data System (ADS)

The treatment of aldehydes (and ketones) with diols in the presence of acid gives acetals (and ketals) in an equilibrium reaction. Treatment of pentaerythritol with benzaldehyde in aqueous acid gives the monoacetal, 5,5-bis(hydroxymethyl)-2-phenyl-1,3-dioxane. The reaction has a number of interesting features. The isolated product is the monobenzal not the dibenzal, and the reaction, a dehydration, is performed in water. The reaction proceeds to provide the acetal owing to the insolubility of the product in the aqueous reaction medium, thus removing the product from the equilibrium. This experiment is suitable for incorporation into the undergraduate organic laboratory as the synthesis of a product for characterization by melting point, solubility, and proton nuclear magnetic resonance. Only through recognition of the three-dimensional structure of the dioxane ring can students explain the appearance of the 1H NMR spectrum of the product. The hydroxymethyl groups of the product are inequivalent, as are the hydrogens of the methylenes in the ring. The experiment may also be presented as a group exercise to optimize the conditions of a reaction to maximize the yield of the desired product.

Collard, David M.; Jones, Adolphus G.; Kriegel, Robert M.

2001-01-01

246

Characterization and thermal dehydration kinetics of highly crystalline mcallisterite, synthesized at low temperatures.  

PubMed

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

Moroydor Derun, Emek; Senberber, Fatma Tugce

2014-01-01

247

Heat shock proteins contribute to mosquito dehydration tolerance  

PubMed Central

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

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

2009-01-01

248

Condensed phase preparation of 2,3-pentanedione  

DOEpatents

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.

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

1998-01-01

249

Condensed phase preparation of 2,3-pentanedione  

DOEpatents

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.

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

1998-11-03

250

Ductile Deformation of Dehydrating Serpentinite Evidenced by Acoustic Signal Monitoring  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

251

EPR study on gamma-irradiated fruits dehydrated via osmosis  

NASA Astrophysics Data System (ADS)

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.

Yordanov, N. D.; Aleksieva, K.

2007-06-01

252

The BUDDY (Bedside Ultrasound to Detect Dehydration in Youth) study  

PubMed Central

Background Prior research suggests that the ratio of the ultrasound-measured diameter of the inferior vena cava to the aorta correlates with the level of dehydration in children. This study was designed to externally validate this and to access the accuracy of the ultrasound measured inspiratory IVC collapse and physician gestalt to predict significant dehydration in children in the emergency department. Methods We prospectively enrolled a non-consecutive cohort of children ?18 years old. Patient weight, ultrasound measurements of the IVC and Ao, and physician gestalt were recorded. The percent weight change from presentation to discharge was used to calculate the degree of dehydration. A weight change of ?5% was considered clinically significant dehydration. Receiver operating characteristic (ROC) curves were constructed for each of the ultrasound measurements and physician gestalt. Sensitivity (SN) and specificity (SP) were calculated based on previously established cutoff points of the IVC/Ao ratio (0.8), the IVC collapsibility index of 50%, and a new cut off point of IVC collapsibility index of 80% or greater. Intra-class correlation coefficients were calculated to assess the degree of inter-rater reliability between ultrasound observers. Results Of 113 patients, 10.6% had significant dehydration. The IVC/Ao ratio had an area under the ROC curve (AUC) of 0.72 (95% CI 0.53 to 0.91) and, with a cutoff of 0.8, produced a SN of 67% and a SP of 71% for the diagnosis of significant dehydration. The IVC collapsibility index of 50% had an AUC of 0.58 (95% CI 0.44 to 0.72) and, with a cutoff of 80% collapsibility, produced a SN of 83% and a SP of 42%. The intra-class correlation coefficient was 0.83 for the IVC/Ao ratio and 0.70 for the IVC collapsibility. Physician gestalt had an AUC of 0.61 (95% CI 0.44 to 0.78) and, with a cutoff point of 5, produced a SN of 42% and a SP of 65%. Conclusions The ultrasound-measured IVC/Ao ratio is a modest predictor of significant dehydration in children. The inspiratory IVC collapse and physician gestalt were poor predictors of the actual level of dehydration in this study. PMID:25411590

2014-01-01

253

Condensate Mixtures and Tunneling  

SciTech Connect

The experimental study of condensate mixtures is a particularly exciting application of the recently developed atomic-trap Bose-Einstein condensate (BEC) technology: such multiple condensates represent the first laboratory systems of distinguishable boson superfluid mixtures. In addition, as the authors point out in this paper, the possibility of inter-condensate tunneling greatly enhances the richness of the condensate mixture physics. Not only does tunneling give rise to the oscillating particle currents between condensates of different chemical potentials, such as those studied extensively in the condensed matter Josephson junction experiments, it also affects the near-equilibrium dynamics and stability of the condensate mixtures. In particular, the stabilizing influence of tunneling with respect to spatial separation (phase separation) could be of considerable practical importance to the atomic trap systems. Furthermore, the creation of mixtures of atomic and molecular condensates could introduce a novel type of tunneling process, involving the conversion of a pair of atomic condensate bosons into a single molecular condensate boson. The static description of condensate mixtures with such type of pair tunneling suggests the possibility of observing dilute condensates with the liquid-like property of a self-determined density.

Timmermans, E.

1998-09-14

254

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

PubMed Central

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

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

2013-01-01

255

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

PubMed

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

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

2013-06-11

256

Diagnosis of Pneumonia in Children with Dehydrating Diarrhoea  

PubMed Central

The World Health Organization (WHO) guidelines for diagnosis of pneumonia are based on the history of cough or difficult breathing and age-adjusted respiration rates. Metabolic acidosis associated with dehydrating diarrhoea also influences the respiration rate. Two hundred and four children, aged 2 to 59 months, with dehydrating diarrhoea and a history of cough and/or fast breathing, were enrolled in a prospective study. Pneumonia diagnoses were made on enrollment and again 6 hours post-enrollment (after initial rehydration), using the WHO guidelines. These were compared with investigators’ clinical diagnosis based on history and findings of physical examination and a chest x-ray at the same time points. Using the WHO guidelines, 149/152 (98%) infants in the 2-11 months age-group and 38/40 (95%) children in the 12-59 months age-group were diagnosed to have pneumonia on enrollment, which dropped to 107 (70%) and 30 (75%) respectively at 6 hours post-enrollment. The specificity of the WHO guidelines for diagnosis of pneumonia was very low (6.9%) at enrollment but increased to 65.5% at 6 hours post-enrollment, after initial rehydration. The specificity of the WHO guidelines for diagnosis of pneumonia in young children is significantly reduced in dehydrating diarrhoea. For young children with dehydrating diarrhoea, rehydration, clinical and radiological assessments are useful in identifying those with true pneumonia. PMID:24847588

Ronan, Anne; Khan, Wasif Ali; Salam, Mohammed Abdus

2014-01-01

257

Solar Drying System for the Agro-products Dehydration  

Microsoft Academic Search

The proposed solar thermodynamic drying system reduces the traditional dehydration process of Roselle used in the western region of Mexico, from approximately four days to four hours. In addition to the 95% reduction in process time, this system also maintains the Roselle's nutritional content, especially that of ascorbic acid (Vitamin C). The proposed drying system is based on current operating

A. CASTAÑEDA-MIRANDA; R. CASTAÑEDA-MIRANDA; J. MEZA JIMENEZ

2008-01-01

258

Natural Gas Dehydration: A Triethylene Glycol-Water System Analysis  

Microsoft Academic Search

Absorption by means of triethylene glycol is one of the most popular methods for natural gas dehydration. In spite of this popularity, thermodynamic modeling of the system TEG-water is still rather inaccurate, especially with regard to systems at high temperature and high TEG concentration, which are typical conditions in the glycol regeneration unit. Available experimental data were selected and correlated

F. Gironi; M. Maschietti; V. Piemonte

2010-01-01

259

Chemical Clearing and Dehydration of GFP Expressing Mouse Brains  

PubMed Central

Generally, chemical tissue clearing is performed by a solution consisting of two parts benzyl benzoate and one part benzyl alcohol. However, prolonged exposure to this mixture markedly reduces the fluorescence of GFP expressing specimens, so that one has to compromise between clearing quality and fluorescence preservation. This can be a severe drawback when working with specimens exhibiting low GFP expression rates. Thus, we screened for a substitute and found that dibenzyl ether (phenylmethoxymethylbenzene, CAS 103-50-4) can be applied as a more GFP-friendly clearing medium. Clearing with dibenzyl ether provides improved tissue transparency and strikingly improved fluorescence intensity in GFP expressing mouse brains and other samples as mouse spinal cords, or embryos. Chemical clearing, staining, and embedding of biological samples mostly requires careful foregoing tissue dehydration. The commonly applied tissue dehydration medium is ethanol, which also can markedly impair GFP fluorescence. Screening for a substitute also for ethanol we found that tetrahydrofuran (CAS 109-99-9) is a more GFP-friendly dehydration medium than ethanol, providing better tissue transparency obtained by successive clearing. Combined, tetrahydrofuran and dibenzyl ether allow dehydration and chemical clearing of even delicate samples for UM, confocal microscopy, and other microscopy techniques. PMID:22479475

Saghafi, Saiedeh; Weiler, Reto; Dodt, Hans-Ulrich

2012-01-01

260

How Do I Know If I Am Dehydrated?  

MedlinePLUS

... drinking water) or you reduce fluid loss (by cooling off and resting)." However, mild dehydration can become more severe if fluid isn't restored. As you lose more water from your body, you may experience symptoms such as dry mouth, flushed skin, fatigue, headache and impaired physical ...

261

Unexpected Preferential Dehydration of Artemisinin in Ionic Liquids  

NASA Astrophysics Data System (ADS)

Thermodynamic measurements (at 298 K) reveal that a crucial step in the extraction process of the key antimalarial drug artemisinin by ionic liquids (ILs), namely, precipitation through the addition of water, is driven by artemisinin dehydration due to the differences in the water's interaction with the bulk ILs, rather than with the artemisinin itself.

Sanders, Marc W.; Wright, Lawrence; Tate, Lauren; Fairless, Gayle; Crowhurst, Lorna; Bruce, Neil C.; Walker, Adam J.; Hembury, Guy A.; Shimizu, Seishi

2009-09-01

262

Compositional Constraints on Dehydration Embrittlement in Serpentinized Peridotite  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

263

Liquid-phase dehydration of aqueous ethanol-gasoline mixtures  

SciTech Connect

Two-phase mixtures of gasoline, water, and ethanol were dehydrated with both starch and saponified starch-g-polyacrylonitrile (HSPAN). Whereas starch absorbed ethanol as well as water, HSPAN selectively absorbed the water component, allowing ethanol to dissolve in the gasoline phase.

Fanta, G.F.; Burr, R.C.; Orton, W.L.; Doane, W.M.

1980-11-07

264

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...

265

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...

266

Age, dehydration and fatigue crack growth in dentin.  

PubMed

A preliminary study of the effects from age and dehydration on fatigue crack growth in human dentin was conducted. Compact tension (CT) fatigue specimens of coronal dentin were prepared from extracted molars and subjected to high cycle fatigue (10(5)dehydrated dentin (mean age=20+/-2 years) were examined. Fatigue crack growth rates were quantified according to the Paris Law in terms of the crack growth exponent (m) and coefficient (C). The average fatigue crack growth exponent for the young hydrated dentin (m=13.3+/-1.1) was significantly less than that for the hydrated old (m=21.6+/-5.2; p<0.003) and dehydrated young dentin (m=18.8+/-2.8; p<0.01). Fatigue cracks in the old dentin underwent initiation at a lower stress intensity range than in young dentin and propagated at as significantly faster rate (over 100x). Differences in the microscopic features of the fracture surfaces from the old and young dentin suggested that particular mechanisms contributing to energy dissipation and crack growth resistance in the young hydrated dentin were not present in the old dentin. Based on results of this study, the fatigue crack growth resistance of human dentin decreases with both age of the tissue and dehydration. PMID:16338002

Bajaj, Devendra; Sundaram, Naryana; Nazari, Ahmad; Arola, D

2006-04-01

267

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— ...

268

Science Study Aids 1: Dehydration for Food Preservation.  

ERIC Educational Resources Information Center

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…

Boeschen, John; And Others

269

Responses of plants to dehydration stress: a molecular analysis  

Microsoft Academic Search

Over more than a decade molecular techniques have been applied to analyse the response of plants to drought with the objective to identify genes which contribute to drought tolerance. The studies have used a variety of experimental strategies, and they have resulted in the characterization of a large number of genes which are expressed upon dehydration. A very prominent group

Dorothea Bartels; Antonella Furini; Jonathan Ingram; Francesco Salamini

1996-01-01

270

Steam Condensation Induced Waterhammer  

E-print Network

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..., TX, April 5-6, 2000 Condensation Induced Waterhammer A condensation induced water hammer is a rapid condensation event. It could also be aptly termed a "rapid steam bubble collapse". It occurs when a steam pocket becomes totally entrapped in sub...

Kirsner, W.

271

in Condensed Matter Physics  

E-print Network

Master in Condensed Matter Physics ­ Master académique #12;2 #12;3 Students at the University. Condensed matter physics is about explaining and predicting the relationship between the atomic, and broad education in the field of condensed matter physics · introduce you to current research topics

van der Torre, Leon

272

40 CFR 63.1275 - Glycol dehydration unit process vent standards.  

Code of Federal Regulations, 2011 CFR

...with actual average benzene glycol dehydration unit process vent...an owner or operator of a glycol dehydration unit process vent...this section. (1) For each glycol dehydration unit process vent...devices through a closed-vent system. The closed-vent system...

2011-07-01

273

40 CFR 63.765 - Glycol dehydration unit process vent standards.  

Code of Federal Regulations, 2010 CFR

...with actual average benzene glycol dehydration unit process vent...an owner or operator of a glycol dehydration unit process vent...this section. (1) For each glycol dehydration unit process vent...devices through a closed-vent system. The closed-vent system...

2010-07-01

274

40 CFR 63.1275 - Glycol dehydration unit process vent standards.  

Code of Federal Regulations, 2010 CFR

...with actual average benzene glycol dehydration unit process vent...an owner or operator of a glycol dehydration unit process vent...this section. (1) For each glycol dehydration unit process vent...devices through a closed-vent system. The closed-vent system...

2010-07-01

275

40 CFR 63.1275 - Glycol dehydration unit process vent standards.  

Code of Federal Regulations, 2012 CFR

...with actual average benzene glycol dehydration unit process vent...an owner or operator of a glycol dehydration unit process vent...this section. (1) For each glycol dehydration unit process vent...devices through a closed-vent system. The closed-vent system...

2012-07-01

276

40 CFR 63.765 - Glycol dehydration unit process vent standards.  

Code of Federal Regulations, 2012 CFR

...with actual average benzene glycol dehydration unit process vent...an owner or operator of a glycol dehydration unit process vent...this section. (1) For each glycol dehydration unit process vent...devices through a closed-vent system. The closed-vent system...

2012-07-01

277

40 CFR 63.765 - Glycol dehydration unit process vent standards.  

Code of Federal Regulations, 2011 CFR

...with actual average benzene glycol dehydration unit process vent...an owner or operator of a glycol dehydration unit process vent...this section. (1) For each glycol dehydration unit process vent...devices through a closed-vent system. The closed-vent system...

2011-07-01

278

Comparative transcriptome analysis of differentially expressed genes in foxtail millet ( Setaria italica L.) during dehydration stress  

Microsoft Academic Search

Dehydration stress is one of the most important abiotic stresses that adversely influence crop growth and productivity. With the aim to understand the molecular mechanisms underlying dehydration stress tolerance in foxtail millet (Setaria italica L.), a drought tolerant crop, we examined its transcriptome changes at two time points (early and late) of dehydration stress. Two suppression subtractive hybridization (SSH) forward

Charu Lata; Pranav Pankaj Sahu; Manoj Prasad

2010-01-01

279

Global transcriptional analysis of dehydrated Salmonella enterica serovar Typhimurium.  

PubMed

Despite the scientific and industrial importance of desiccation tolerance in Salmonella, knowledge regarding its genetic basis is still scarce. In the present study, we performed a transcriptomic analysis of dehydrated and water-suspended Salmonella enterica serovar Typhimurium using microarrays. Dehydration induced expression of 90 genes and downregulated that of 7 genes. Ribosomal structural genes represented the most abundant functional group with a relatively higher transcription during dehydration. Other main induced functional groups included genes involved in amino acid metabolism, energy production, ion transport, transcription, and stress response. The highest induction was observed in the kdpFABC operon, encoding a potassium transport channel. Knockout mutations were generated in nine upregulated genes. Five mutants displayed lower tolerance to desiccation, implying the involvement of the corresponding genes in the adaptation of Salmonella to desiccation. These included genes encoding the isocitrate-lyase AceA, the lipid A biosynthesis palmitoleoyl-acyltransferase Ddg, the modular iron-sulfur cluster scaffolding protein NifU, the global regulator Fnr, and the alternative sigma factor RpoE. Notably, these proteins were previously implicated in the response of Salmonella to oxidative stress, heat shock, and cold shock. A strain with a mutation in the structural gene kdpA had a tolerance to dehydration comparable to that of the parent strain, implying that potassium transport through this system is dispensable for early adaptation to the dry environment. Nevertheless, this mutant was significantly impaired in long-term persistence during cold storage. Our findings indicate the involvement of a relatively small fraction of the Salmonella genome in transcriptional adjustment from water to dehydration, with a high prevalence of genes belonging to the protein biosynthesis machinery. PMID:22941081

Gruzdev, Nadia; McClelland, Michael; Porwollik, Steffen; Ofaim, Shany; Pinto, Riky; Saldinger-Sela, Shlomo

2012-11-01

280

Meat tenderization by proteolytic enzymes after osmotic dehydration.  

PubMed

The treatment of proteolytic enzymes is one of the popular methods for meat tenderization. In this case, it is very important how to introduce the enzymes into the meat cut. This paper describes meat tenderization by dipping the meat cut in a solution containing proteolytic enzymes after contact-osmotic dehydration. After the dehydration of each piece of meat from culled cow for 18 h by contact-dehydration sheet, each sample was dipped for 3 h in a solution containing papain or proteinases from Aspergillus traditionally used for soysauce production in Japan. It was stored at 3?4°C for 24, 48 and 168 h, and subjected to texture measurement, sensory evaluations, biochemical analysis and histological observations. The penetration efficiency of the enzyme solution (of around 80%) after the contact-osmotic dehydration seemed to be sufficient. A marked decrease in hardness by texture measurements was observed in the meats treated with proteolytic enzymes and higher sensory scores for tenderness were observed in the meats treated with enzymes as compared with the untreated meat. The papain-treated meat received the highest score in tenderness, but the scores given to juiciness and taste were lower than that of the control. The rapid increases of the fragmentation of myofibrils from the enzyme-treated meat were observed at first 24 h of storage as compared with that of the control. Remarkable degradation of myosin molecule in the myofibrils from the enzyme-treated meats was observed on SDS-PAGE profiles. Considerable degradation of myofibrilar structure especially due to proteolytic removal of Z-lines, was observed among the myofibrils from enzyme-treated meats by electronmicroscopy. The remarkable deformation and disruption of honeycomb-like structure of endomysium were also observed in the meats treated with enzymes. From these results, it was shown that treatment after osmotic dehydration, was effective in tenderizing. PMID:22062083

Gerelt, B; Ikeuchi, Y; Suzuki, A

2000-11-01

281

Intermediate-depth earthquakes within young Cocos plate beneath Central Mexico: A hypothesis test for dehydration embrittlement and shear instability  

NASA Astrophysics Data System (ADS)

Subducting slab undergoes a series of dehydration reactions on their ways into the mantle and these processes are responsible for transporting water, recycling volatiles and chemical elements in arc magmas. It is generally accepted that the SOC is hydrated. However, it is not clear if subducting oceanic mantle (SOM) is hydrated and how deep the hydration is. Seismic refraction studies found that normal-fault type faulting can extend 12-20 km deep into the interior of the slab off Nicaragua, suggesting deep hydration of the SOM. Seismic refraction studies also found that the uppermost SOM is seismically slow and is partially serpentinized. The fluids released from dehydration inside the SOM can reduce the normal stress locally and facilitate the occurrences of intra-slab events through dehydration embrittlement and hydraulic fracture. It has been suggested that the dehydration of antigorite at about 600C is particularly important in facilitating the lower plane of the double seismic zone. To link the dehydration process to the occurrences of intra-slab events, it is critical to clarify where these events are located, either located at the dehydration boundary or in the neighborhood rocks. However, if the SOM is anhydrous, other mechanism, such as shear instabilities, has to be invoked to explain the occurrences of intermediate-depth intraslab earthquakes. Here I discuss locations of intermediate-depth intraslab earthquakes in Central Mexico subduction zone, where young Cocos plate subducts beneath North America plate. Recent studies involving local converted wave modeling and receiver function analysis indicate the presence of an ultra-slow velocity layer (USL) of about 3 km thick, likely an over-pressured upper oceanic crust. Most events display anomalously large converted SP waves that are 2-2.5 secs after direct P waves and finite difference modeling converge the location of these events about 9 km below the lower boundary USL. With a lower oceanic crust of about 3-5 km estimated from receiver function, these intermediate-depth earthquakes are about 6 km inside the SOM. There is no clear evidence yet indicating the presence of a partially serpentinized layer in such a young plate (10-15 Ma). Further waveform modeling is undertaken to explore the presence of such a partially serpentinized layer.

Song, T.

2010-12-01

282

Condensed Matter Nuclear Science  

NASA Astrophysics Data System (ADS)

1. General. A tribute to gene Mallove - the "Genie" reactor / K. Wallace and R. Stringham. An update of LENR for ICCF-11 (short course, 10/31/04) / E. Storms. New physical effects in metal deuterides / P. L. Hagelstein ... [et al.]. Reproducibility, controllability, and optimization of LENR experiments / D. J. Nagel -- 2. Experiments. Electrochemistry. Evidence of electromagnetic radiation from Ni-H systems / S. Focardi ... [et al.]. Superwave reality / I. Dardik. Excess heat in electrolysis experiments at energetics technologies / I. Dardik ... [et al.]. "Excess heat" during electrolysis in platinum/K[symbol]CO[symbol]/nickel light water system / J. Tian ... [et al.]. Innovative procedure for the, in situ, measurement of the resistive thermal coefficient of H(D)/Pd during electrolysis; cross-comparison of new elements detected in the Th-Hg-Pd-D(H) electrolytic cells / F. Celani ... [et al.]. Emergence of a high-temperature superconductivity in hydrogen cycled Pd compounds as an evidence for superstoihiometric H/D sites / A. Lipson ... [et al.]. Plasma electrolysis. Calorimetry of energy-efficient glow discharge - apparatus design and calibration / T. B. Benson and T. O. Passell. Generation of heat and products during plasma electrolysis / T. Mizuno ... [et al.]. Glow discharge. Excess heat production in Pd/D during periodic pulse discharge current in various conditions / A. B. Karabut. Beam experiments. Accelerator experiments and theoretical models for the electron screening effect in metallic environments / A. Huke, K. Czerski, and P. Heide. Evidence for a target-material dependence of the neutron-proton branching ratio in d+d reactions for deuteron energies below 20keV / A. Huke ... [et al.]. Experiments on condensed matter nuclear events in Kobe University / T. Minari ... [et al.]. Electron screening constraints for the cold fusion / K. Czerski, P. Heide, and A. Huke. Cavitation. Low mass 1.6 MHz sonofusion reactor / R. Stringham. Particle detection. Research into characteristics of X-ray emission laser beams from solidstate cathode medium of high-current glow discharge / A. B. Karabut. Charged particles from Ti and Pd foils / L. Kowalski ... [et al.]. Cr-39 track detectors in cold fusion experiments: review and perspectives / A. S. Roussetski. Energetic particle shower in the vapor from electrolysis / R. A. Oriani and J. C. Fisher. Nuclear reactions produced in an operating electrolysis cell / R. A. Oriani and J. C. Fisher. Evidence of microscopic ball lightning in cold fusion experiments / E. H. Lewis. Neutron emission from D[symbol] gas in magnetic fields under low temperature / T. Mizuno ... [et al.]. Energetic charged particle emission from hydrogen-loaded Pd and Ti cathodes and its enhancement by He-4 implantation / A. G. Lipson ... [et al.]. H-D permeation. Observation of nuclear transmutation reactions induced by D[symbol] gas permeation through Pd complexes / Y. Iwamura ... [et al.]. Deuterium (hydrogen) flux permeating through palladium and condensed matter nuclear science / Q. M. Wei ... [et al.]. Triggering. Precursors and the fusion reactions in polarized Pd/D-D[symbol]O system: effect of an external electric field / S. Szpak, P. A. Mosier-Boss, and F. E. Gordon. Calorimetric and neutron diagnostics of liquids during laser irradiation / Yu. N. Bazhutov ... [et al.]. Anomalous neutron capture and plastic deformation of Cu and Pd cathodes during electrolysis in a weak thermalized neutron field: evidence of nuclei-lattice exchange / A. G. Lipson and G. H. Miley. H-D loading. An overview of experimental studies on H/Pd over-loading with thin Pd wires and different electrolytic solutions / A. Spallone ... [et al.] -- 3. Transmutations. Photon and particle emission, heat production, and surface transformation in Ni-H system / E. Campari ... [et al.]. Surface analysis of hydrogen-loaded nickel alloys / E. Campari ... [et al.]. Low-energy nuclear reactions and the leptonic monopole / G. Lochak and L. Urutskoev. Results of analysis of Ti foil after glow discharge with deuterium / I. B. Savvat

Biberian, Jean-Paul

2006-02-01

283

The kinetics of condensation behind the shock front  

Microsoft Academic Search

The growth and evaporation of clusters is considered in the frame of a quasichemical model of condensation. The rate coefficients of growth and evaporation reactions are calculated using the molecular dynamics method. Condensation of supersaturated Fe vapor behind the shock front is studied. For an explanation of known experimental data the chemical mechanism of dimer formation is considered. Probabilities of

Z. A. Insepov; E. M. Karatajev; G. E. Norman

1991-01-01

284

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

PubMed Central

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

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

285

Contrasting fracture patterns induced by volume-increasing and -decreasing reactions: Implications for the progress of metamorphic reactions  

NASA Astrophysics Data System (ADS)

Hydration and dehydration reactions during metamorphism cause drastic changes in porosity and fluid pressure in a rock, and some of these reactions proceed with fracturing. For this paper we have developed a model for coupled hydraulic-chemical-mechanical processes, using the distinct element method, in order to understand the relationships among chemical reactions, fluid flow, and fracturing during metamorphism. The model considers fluid advection along fractures and the dependence of reaction rates on fluid pressure. With the help of the model, volume-decreasing dehydration reactions and volume-increasing hydration reactions are investigated in detail as analogs of prograde and retrograde reactions, respectively. Both types of reaction proceed inwards from drained boundaries or fractures, but they show contrasting fracture patterns. A volume-decreasing dehydration reaction produces tree-type fractures, with the new fractures generated as branches of a pre-existing fracture. A volume-increasing hydration reaction produces a polygonal network of fractures, where new fractures nucleate at sites far from the pre-existing fracture, and extend to form T-junctions. These contrasting fracture patterns are essentially controlled by solid volume changes during reaction rather than by the fluid pressure gradient. In the case of the tree-type fractures, the fractures are continuously generated at the reaction front, and the reaction proceeds smoothly by positive feedbacks between reaction, fracturing, and fluid flow. In contrast, in a volume-increasing hydration reaction, fracturing initially occurs in response to the irregular boundary shape, but as the reaction progresses, a compressive stress field is generated, which inhibits further fracture generation. The compressive stress field also prevents fluid flow by closing the pre-existing fractures, which slows down the reaction. These contrasting feedback systems between volume-decreasing dehydration and volume-increasing hydration reactions help to explain why prograde metamorphic reactions proceed pervasively, and why the progress of a retrograde hydration reaction tends to be localized along fractures so that relics of peak metamorphism are commonly preserved.

Okamoto, Atsushi; Shimizu, Hiroyuki

2015-05-01

286

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

NASA Astrophysics Data System (ADS)

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.

Spandler, Carl; Pettke, Thomas; Hermann, Joerg

2014-04-01

287

Proceedings: Condenser technology conference  

SciTech Connect

Seam surface condenser and associated systems performance strongly affects availability and heat rate in nuclear and fossil power plants. Thirty-six papers presented at a 1990 conference discuss research results, industry experience, and case histories of condenser problems and solutions. This report contains papers on life extension, performance improvement, corrosion and failure analysis, fouling prevention, and recommendation for future R D. The information represents recent work on condenser problems and solutions to improve the procurement, operation, and maintenance functions of power plant personnel. Several key points follow: A nuclear and a fossil power plant report show that replacing titanium tube bundles improves condenser availability and performance. One paper reports 10 years of experience with enhanced heat transfer tubes in utility condensers. The newly developed enhanced condenser tubes could further improve condensing heat transfer. A new resistance summation method improves the accuracy of condenser performance prediction, especially for stainless steel and titanium tubed condensers. Several papers describe improved condenser fouling monitoring techniques, including a review of zebra mussel issues.

Tsou, J.L. (ed.)(Electric Power Research Inst., Palo Alto, CA (United States)); Mussalli, Y.G. (comp.)(Stone and Webster Engineering Corp., Boston, MA (United States))

1991-08-01

288

Effect of feeding dehydrated and ensiled tanniferous sainfoin (Onobrychis viciifolia) on nitrogen and mineral digestion and metabolism of lambs.  

PubMed

The effects of tanniferous sainfoin on digestion and metabolism have been investigated in 12 lambs in an incomplete cross-over design (n = 6). Effects of condensed tannins (CT) were evaluated by comparing dehydrated and ensiled sainfoin treated with and without polyethylene glycol (PEG). Dehydrated and ensiled grass-clover mixtures served as controls. The lambs were fed the treatment diets, including a mineral supplement, for 21 d. During the last 7 d excreta, rumen fluid and blood were sampled. The CT of sainfoin decreased rumen fluid ammonia concentration (p < 0.001) and increased the plasma concentration mainly of essential amino acids (p < 0.001). Body retention of phosphorus, calcium and magnesium was lower with sainfoin compared to PEG-treated sainfoin (p < 0.05). Sainfoin without PEG resulted in lower digestibilities of organic matter and neutral detergent fibre than sainfoin with PEG and the grass-clover mixture (p < 0.001). Ensiling of sainfoin led to the lowest N-retention. In conclusion, the reduction in ruminal ammonia and urine-N losses by sainfoin CT did not improve N-retention. PMID:18030920

Scharenberg, Anna; Arrigo, Yves; Gutzwiller, Andreas; Wyss, Ueli; Hess, Hans D; Kreuzer, Michael; Dohme, Frigga

2007-10-01

289

Specification for glycol-type gas dehydration units  

SciTech Connect

This specification covers minimum requirements for materials, design, fabrication and testing of a conventional lease glycol-type gas dehydration system utilizing triethylene glycol as the desiccant. Conventional systems are normally designed to operate at an inlet temperature between 60{degrees}F and 120{degrees}F and at or above 400 psig pressure but not to exceed pressure limited by ANSI B16.5 Class flanges. This API specification encompasses a system which includes an inlet separator, a glycol/gas contractor, gas/glycol heat exchanger, glycol reboiler, glycol surge tank, glycol circulating pump(s), filter(s), glycol/glycol heat exchanger, glycol flash separator (optional) and skid(s). While this specification does not preclude dehydrators for service on offshore platforms, it should be noted that considerable additional requirements may apply to offshore units.

Not Available

1990-01-01

290

LEA proteins: IDPs with versatile functions in cellular dehydration tolerance.  

PubMed

LEA (late embryogenesis abundant) proteins were originally described almost 30 years ago as accumulating late in plant seed development. They were later found to be induced in vegetative plant tissues under environmental stress conditions and also in desiccation-tolerant micro-organisms and invertebrates. Although they are widely assumed to play crucial roles in cellular dehydration tolerance, their physiological and biochemical functions are largely unknown. Most LEA proteins are predicted to be intrinsically disordered and this has been experimentally verified in several cases. In addition, some LEA proteins partially fold, mainly into ?-helices, during drying or in the presence of membranes. Recent studies have concentrated on the potential roles of LEA proteins in stabilizing membranes or sensitive enzymes during freezing or drying, and the present review concentrates on these two possible functions of LEA proteins in cellular dehydration tolerance. PMID:22988854

Hincha, Dirk K; Thalhammer, Anja

2012-10-01

291

Methods for dehydration of sugars and sugar alcohols  

DOEpatents

The invention includes a method of dehydration of a sugar using a dehydration catalyst and a co-catalyst within a reactor. A sugar is introduced and H.sub.2 is flowed through the reactor at a pressure of less than or equal to about 300 psig to convert at least some of the sugar into an anhydrosugar product. The invention includes a process for producing isosorbide. A starting material comprising sorbitol is flowed into a reactor. H.sub.2 is counter flowed through the reactor. The starting material is exposed to a catalyst in the presence of a co-catalyst which comprises at least one metal. The exposing is conducted at a hydrogen pressure of less than or equal to 300 psig within the reactor and the hydrogen removes at least some of any water present during the exposing and inhibits formation of colored byproducts.

Holladay, Johnathan E [Kennewick, WA; Hu, Jianli [Kennewick, WA; Zhang, Xinjie [Burlington, MA; Wang, Yong [Richland, WA

2010-08-10

292

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

PubMed Central

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

Okpala, Laura C; Ekechi, Constance A

2014-01-01

293

Hydration and dehydration of Zeolitic Tuff from Yucca Mountain, Nevada  

NASA Astrophysics Data System (ADS)

Naturally occurring zeolites expand and contract when hydrated or dehydrated. In tuffaceous rock composed largely of such zeolites, the entire rock may swell or contract significantly as the rock becomes saturated or dries out. If such rock is constrained, significant stresses may develop as a result of hydration or dehydration. We present experimental results that substantiate this. In a zeolitized, non-welded tuff from Yucca Mountain, NV, rock permeability governs the swelling rate since the major constituent, clinoptilolite, hydrates as fast as it can be exposed to water. At Yucca Mountain, where a nuclear waste repository is proposed, strata of welded, devitrified tuff overlie non-welded, zeolitic tuff. Should the hydration state of the units change significantly over the repository lifetime, additional stresses on the same order of magnitude as now exist may develop.

Kranz, R. L.; Bish, D. L.; Blacic, J. D.

1989-10-01

294

Hydrothermal Dehydration of Aqueous Fructose Solutions in a Closed System  

SciTech Connect

The synthesis of materials with targeted size and shape has attracted much attention. Specifically, colloidal spheres with targeted and uniform sizes have opened the door for a variety of applications associated with drug delivery, and manipulation of light (photonic band-gap crystals). Surface modification is a key to realizing many of these applications owing to the inherent inert surface.The remarkable transformation of carbohydrate molecules including sugars to homogeneous carbon spheres is found to readily occur by a dehydration mechanism and subsequent sequestering in aqueous solutions that are heated at 160-180oC in a pressurized vessel. Under such conditions, these molecules actually dehydrate even though they are dissolved in water. Size-tunable metal and metal oxides with uniform shells have also been prepared by using carbon spheres as templates.

Yao, Chunhua; Shin, Yongsoon; Wang, Li Q.; Windisch, Charles F.; Samuels, William D.; Arey, Bruce W.; Wang, Chong M.; Risen Jr., William M.; Exarhos, Gregory J.

2007-10-25

295

Using the spent alumina catalysts of methyl phenyl carbinol dehydration  

Microsoft Academic Search

To assess the possibility of using spent alumina catalysts from the vapor-phase dehydration of methyl phenyl carbinol as a\\u000a support of fixed-bed catalysts, we determined the textural changes and mechanical strength of the catalyst over its scheduled\\u000a service life of 8000 h. It was found that the catalytic properties of a palladium catalyst prepared on this support (0.2 wt\\u000a %

E. A. Karalin; D. V. Ksenofontov; I. V. Soldatov; N. P. Miroshkin; Kh. E. Kharlampidi; A. G. Abramov; A. S. Pavlov; T. V. Turkova; A. I. Aleshin; T. V. Borisova; N. V. Elokhina

2010-01-01

296

POLYPHENOL OXIDASE ACTIVITY IN BANANA CHIPS DURING OSMOTIC DEHYDRATION  

Microsoft Academic Search

Various treatments were used to determine polyphenol oxidase activity changes during osmotic dehydration of banana slices. A temperature of 35 °C and 5.0 pH were used as the most adequate conditions for polyphenol oxidase activity determination when 4-methyl catechol was used as a substrate. Enzyme activity change was determined in the central and edge region of fruit. The central part

K. N. Waliszewski; R. H. Garcia; M. Ramirez; M. A. Garcia

2000-01-01

297

Microwave-assisted air dehydration of apple and mushroom  

Microsoft Academic Search

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

Tomas Funebo; Thomas Ohlsson

1998-01-01

298

A prospective clinical study of patients with hypernatraemic dehydration.  

PubMed

In a clinical prospective 3-year study of 158 children aged 2 weeks to 14 years with hypernatraemic dehydration (serum sodium 150 mmol/l or more), infants predominated (61.4%). The 158 children with hypernatraemia accounted for 13.7% of all children admitted with gastroenteritis over the same period, and significant aetiological factors included the use of artificial feeds, differences between the children with hypernatraemia and those with normo- or hyponatraemia, P < 0.001, P < 0.001, respectively; the use of breast milk, P < 0.001, P < 0.001, respectively; nutritional status, P < 0.001, P < 0.001, respectively; and clinical state of mild to moderate dehydration P < 0.001; P < 0.001, respectively; but not with patients considered severely dehydrated. There was also a significant difference between the presence of neurological features in hyper- and normonatraemic patients P < 0.001; in hyper- and hyponatraemic patients P < 0.05, and in mortality rate between hyper- and normonatraemic patients, P < 0.05 but not between hyper- and hyponatraemic patients. A history of refusal to feed or vomiting was obtained in 41 children (25.9%). The mean serum sodium was 155.5 mmol/l (range 150-189 mmol/l); mean serum urea 7.7 mmol/l (range 1-18.9 mmol/l). Hypernatraemic dehydration remains an important and serious complication of childhood gastroenteritis in our area of study. The use of artificial milk feeds is contributory, and well-nourished babies appear more at risk. We recommend more liberal water intake during gastroenteritis and the public should also be educated on and made more aware of this condition. PMID:10457791

Eke, F; Nte, A

1996-09-01

299

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

300

Histological structure and commercial dehydration potential of breadfruit  

Microsoft Academic Search

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

Roger M. Reeve

1974-01-01

301

Investigations on the cause of electrocardiogram changes during dehydration  

E-print Network

described plasma potassium increases after high x-ray doses in dogs (1400-2S00 R) , :nd rabbit, s (HSO R), respe~ 's v~ ly. In other radiation xperiments ' animals 1'ailcd to develop hyperkalemia after exposure. The report of Caster et al. described... surface, or a combination of boih factors. In the study of Bzabuniewicz and Clark random blood samples from dehydrated goats revealed marked hemoconcentration and moderate hyperkalemia. Other re- ports concerning experimental dehydra*ion9? agreed...

Clark, Donald Ray

1966-01-01

302

Mechanism and temperature-dependent kinetics of the dehydration of tert-butyl alcohol in hot compressed liquid water  

SciTech Connect

In the presence of acid or base, or under neutral conditions, isobutylene is the only observed product of the reactions of tert-butyl alcohol in compressed liquid water at 225, 250, and 320 C. On the basis of a kinetic analysis of limited results at 250 C, an earlier paper concluded that tert-butyl alcohol dissociates as an Arrhenius acid at 250 C and thereby catalyzes its own dehydration to isobutylene. Kinetic analyses of the data sets contained in this paper do not corroborate the alleged ability of tert-butyl alcohol to protonate water. Instead, the authors find that hydronium ions formed by the ordinary dissociation of water are the primary catalytic agents for the dehydration reaction. In agreement with the earlier work, all three data sets are consistent with a heterolytic reaction mechanism involving protonated alcohol, carbocation, di-tert-butyl ether, and protonated ether as intermediates. The kinetics still suggest that tert-butyl alcohol weakly dissociated as a Bronsted acid at these conditions. Values of K{sub w} determined by the kinetic model enjoy good agreement with electrochemical values available in the literature. Values of the other parameters (rate constants) which compose the kinetic model are evaluated with less precision, and a novel method is proposed to estimate the uncertainty associated with each parameter.

Xu, X.; Antal, M.J. Jr. [Univ. of Hawaii, Honolulu, HI (United States)] [Univ. of Hawaii, Honolulu, HI (United States); Anderson, D.G.M. [Harvard Univ., Cambridge, MA (United States). Aiken Computation Lab.] [Harvard Univ., Cambridge, MA (United States). Aiken Computation Lab.

1997-01-01

303

Dehydration Influences Mood and Cognition: A Plausible Hypothesis?  

PubMed Central

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

Benton, David

2011-01-01

304

Inhibition of plasma vasopressin after drinking in dehydrated humans  

NASA Technical Reports Server (NTRS)

The effects of nonosmotic and nonvolumetric factors on vasopressin secretion in dehydrated humans has been investigated experimentally, before and after drinking. The subjects of the experiment were five adult men and three adult women weighing 69-77 kg. In order to determine the influence of nonosmotic and nonvolumetric factors on vasopressin secretion, measurements were obtained of the following blood hematological indices: serum Na(+) content; serum K(+) content; osmolality; and hemoglobin. Measurements of hematocrit, plasma arginine vasopressin (AVP), aldosterone, and renin activity were also obtained. It is found that dehydration increased mean serum Na(+) content, osmolality,and AVP. No significant changes were observed in renin activity, hemoglobin, hematocrit, or plasma volume, while plasma aldosterone increased from 11.1 ng/dl after dehydration to 15.6 ng/dl between 30 and 60 min after drinking. A rapid fall of AVP content following rehydration occurred in the absence of changes in the primary regulators of AVP osmolality and plasma volume, with no change in blood pressure. On the basis of the experimental results, it is suggested that oropharyngeal factors may be the mechanism, for the observed decrease in AVP following rehydration.

Geelen, G.; Keil, L. C.; Kravik, S. E.; Wade, C. E.; Thrasher, T. N.; Barnes, P. R.; Pyka, G.; Nesvig, C.; Greenleaf, J. E.

1984-01-01

305

Modeling of B concentrations and isotopic compositions in subducted slabs and dehydration fluids  

NASA Astrophysics Data System (ADS)

The oceanic lithosphere plays a key role regarding global scale element cycles. Seawater-rock interaction at the ocean floor causes intense chemical modification of the basaltic oceanic crust and possibly also the upper parts of the oceanic mantle. Later subduction of the modified oceanic lithosphere leads to dehydration, which again enables redistribution of major and trace elements in the subducted slab. This dehydration process is responsible for arc volcanism, subduction-related ore formation but also controls the distribution of elements that are recycled into the upper plate and the atmosphere and those that are incorporated into refractory minerals and are recycled into the deeper mantle. Regarding the water budget and thus the element transport in a subduction zone, the potentially hydrated oceanic mantle plays a major role as it can store large amounts of water in hydrous minerals, such as chlorite and serpentine. The pressure and temperature conditions as well as the fluid-rock interaction within the subducted slab controls whether water - and elements solved therein - can escape the slab or are deeply subducted and recycled into the Earth's mantle. Boron concentrations and isotopic compositions are excellent tracers for the contribution of oceanic lithospheric mantle to the water and trace element budget in subduction zones: boron is incorporated at significant amounts in serpentine, it is highly fluid mobile and its two stable isotopes (10B and 11B) undergo equilibrium fractionation between fluid and solid phases. In this contribution, thermal and thermodynamic models of subduction of oceanic lithosphere are combined with trace element and isotope partitioning data in order to quantify boron concentrations and its isotopic composition in coexisting fluid and solid phases during devolatilisation, fluid migration and fluid-rock interaction in a subducted slab. The results show that fluid-mobile elements undergo complex liberation and resorption processes during fluid migration in a dehydrating slab, which leads to re-enrichment of previously leached lithologies. Such internal redistribution of trace elements within the slab enables recycling of fluid mobile elements beyond the dehydration interval into the deep mantle beyond sub-arc depths. Further, this study shows that across arc variations of the isotopic composition of boron in arc volcanics can be used as indicator for the hydration state of the subducted oceanic mantle lithosphere. Increases in boron concentrations and ?11B in rear- and back-arc volcanic rocks, as observed for example in Kamchatka and Northern Japan, can be explained by dehydration of serpentinized upper oceanic mantle.This release occurs over a small pressure and temperature range and, despite intense fluid-rock interaction in the slab crust, the associated trace element signal is transferred to the slab surface and into the mantle wedge. The position of the serpentinite-out reaction and thus the associated trace element signal is dependent on the thermal structure within the slab. Consequently complex across-arc variations in boron concentrations and boron isotopic compositions can be used as constraining parameters in thermomechanical subduction zone models.

Konrad-Schmolke, Matthias

2013-04-01

306

Economical Condensing Turbines?  

E-print Network

Economical Condensing Turbines? by J.E.Dean, P.E. Steam turbines have long been used at utilities and in industry to generate power. There are three basic types of steam turbines: condensing, letdown 1 and extraction/condensing. ? Letdown... turbines reduce the pressure of the incoming steam to one or more pressures and generate power very efficiently, assuming that all the letdown steam has a use. Two caveats: ? Letdown turbines produce power based upon steam requirements and not based upon...

Dean, J. E.

307

Atomic structure and dehydration mechanism of amorphous silica: Insights from 29Si and 1H solid-state MAS NMR study of SiO2 nanoparticles  

NASA Astrophysics Data System (ADS)

Detailed knowledge of the atomic structure of hydrous species on surface of amorphous silica and the effect of temperature and particle size on their atomic configurations are essential to understand the nature of fluids-amorphous silicates interactions and the dehydration processes in the amorphous oxides. Here, we report the 29Si, 1H MAS, and 1H-29Si heteronuclear correlation (HetCor) NMR spectra of 7 nm and 14 nm amorphous silica nanoparticles—a model system for natural amorphous silica—where previously unknown details of changes in their atomic structures with varying dehydration temperature and particle size are revealed. Diverse hydroxyl groups with varying atomic configurations and molecular water apparently show distinct dehydration trends. The dehydration (i.e., removal of water) of amorphous silica nanoparticles mostly results in the increase of isolated silanol by removing water molecules from hydrogen-bonded silanols associated water molecules. With further increase in dehydration temperature, the intensity of isolated silanol peak decreases above ˜873 K, suggesting that the condensation of isolated silanol may occur mainly above ˜873 K. The entire dehydration (and dehydroxylation) process completes at ˜1473 K. Both the water (i.e., physisorbed water and hydrogen-bonded water) and hydrogen-bonded silanol species show a dramatic change in the slope of intensity variation at ˜873 K, indicating that most of silanols is hydrogen-bonded to water rather than to other silanols. The fraction of hydrogen-bonded proton species is also much smaller in 14 nm amorphous silica nanoparticles than in 7 nm amorphous silica nanoparticles mainly due to the presences of larger fractions of water and hydrogen-bonded silanol species. 29Si NMR results show that with increasing dehydration temperature, the fraction of Q4 species apparently increases at the expense of Q2 and Q3 species. The fractions of Q2 and Q3 structures in 7 nm amorphous silica nanoparticles are larger than those in 14 nm amorphous silica nanoparticles. Dehydration of 7 nm amorphous silica nanoparticles occurs at a lower temperature than that of 14 nm amorphous silica nanoparticles. 29Si MAS NMR results show that a possible simultaneous dehydroxylation can also occur with removal of the hydrogen bonded silanol in the 7 nm silica nanoparticles. The energy penalty of dehydroxylation estimated from 29Si MAS NMR spectra varies with Q species and is smaller in 7 nm than in 14 nm amorphous silica nanoparticles. These results demonstrate that the particle size of nanoparticles plays an important role in controlling the hydrogen contents, and thus overall hydrogen bond strength of hydroxyl groups and atomic structure of silanols can control dehydroxylation of amorphous silica nanoparticles. The structural information and mechanistic details obtained from the current study provide insights into the structure of hydrous species and dehydration mechanisms in crystalline and amorphous silicates in diverse geological settings, highlighting usually unknown effects of particle size on the dehydration processes.

Kim, Hyun Na; Lee, Sung Keun

2013-11-01

308

Steam and Condensate Systems  

E-print Network

types of traps. Our data shows that most types have low losses when sized and in stalled properly. Virtually any condensate removel device will waste steam or fail prematurely if impro perly sized or installed. When selecting steam traps, factors... year and it can fail prematurely due to improper selection or installation. What is a steam trap? It is an automatic control valve that opens on condensate, air and non-condensable gases and closes on steam or hot condensate. The basic types are...

Yates, W.

1980-01-01

309

Condensed Matter Physics  

NSDL National Science Digital Library

Founded in 1993 by the Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, the journal Condensed Matter Physics is a peer-reviewed, English-language journal covering such aspects of condensed matter as phase transition theory, statistical mechanics of spin and spin-electron systems, metals and alloys, liquids, solutions, electrolytes, surface phenomena, and plasma physics. Selected issues of Condensed Matter Physics from January 1994 to March 2000 are now available free, online in LaTeX format.

310

Of Matters Condensed  

E-print Network

The American Physical Society (APS) March Meeting of condensed matter physics has grown to nearly 10,000 participants, comprises 23 individual APS groups, and even warrants its own hashtag (#apsmarch). Here we analyze the text and data from March Meeting abstracts of the past nine years and discuss trends in condensed matter physics over this time period. We find that in comparison to atomic, molecular, and optical physics, condensed matter changes rapidly, and that condensed matter appears to be moving increasingly toward subject matter that is traditionally in materials science and engineering.

Shulman, Michael

2015-01-01

311

Effects of dehydration and rehydration on thermoregulatory sweating in goats.  

PubMed Central

1. Measurement of rectal temperature (Tr), sweat rate, respiratory frequency (f) and respiratory evaporation (Eresp) were made in one Nubian and four Alpine-Toggenberg goats while they stood for 90 min in a climate chamber at 40 degrees C ambient temperature (Ta). The animals were studied when they were hydrated, when they had been dehydrated by 48 h water deprivation, and when they were rehydrated by voluntary drinking of water or saline or by intraruminal water administration. Plasma osmolality (Posm), plasma protein concentration (PP) and haematocrit (Hct) were measured before every experiment and before and after voluntary drinking. 2. Hydrated animals increased evaporation by panting and sweating during heat exposure and Tr rose about 1 degree C. The rate of sweating was as high or higher than Eresp. Dehydrated animals had lower sweat rates and higher Tr than hydrated animals, but f and Eresp were the same in hydrated and dehydrated animals. 3. When dehydrated goats were allowed to drink after 60 min of heat exposure, sweating began abruptly within 3 min of the start of drinking in every animal whether water or saline was drunk. Sweat rate returned to hydrated levels or higher before any change occurred in Posm, PP or Hct. Respiratory frequency was higher after drinking than in dehydrated animals which were not allowed to drink. 4. When water was administered by rumen tube after 60 min of heat exposure, sweating in the Nubian occurred with a short latency, similar to the onset after drinking. In the other four animals, sweating onset occurred on average at 13 min 42 s after intraruminal water administration. 5. It is concluded that sweating is a significant avenue of evaporative heat loss in these goats when they are hydrated and exposed to high Ta. Sweat rate is markedly reduced after water deprivation but returns to hydrated levels within 3 min after the start of drinking. The rapid recovery of sweating after voluntary drinking is not initiated by changes in Posm or in blood volume and does not appear to depend upon osmoreceptors in the mouth or gastrointestinal tract since it occurs after drinking either water or saline. The arrival of water in the rumen may be sufficient to initiate immediate sweating in some goats, but the act of drinking is necessary in others. PMID:2621603

Baker, M A

1989-01-01

312

Analysis of Dehydration and Strength in Elite Badminton Players  

PubMed Central

Background The negative effects of dehydration on aerobic activities are well established. However, it is unknown how dehydration affects intermittent sports performance. The purpose of this study was to identify the level of dehydration in elite badminton players and its relation to muscle strength and power production. Methodology Seventy matches from the National Spanish badminton championship were analyzed (46 men’s singles and 24 women’s singles). Before and after each match, jump height and power production were determined during a countermovement jump on a force platform. Participants’ body weight and a urine sample were also obtained before and after each match. The amount of liquid that the players drank during the match was also calculated by weighing their individual drinking bottles. Results and Discussion Sweat rate during the game was 1.14±0.46 l/h in men and 1.02±0.64 l/h in women. The players rehydrated at a rate of 1.10±0.55 l/h and 1.01±0.44 l/h in the male and female groups respectively. Thus, the dehydration attained during the game was only 0.37±0.50% in men and 0.32±0.83% in women. No differences were found in any of the parameters analyzed during the vertical jump (men: from 31.82±5.29 to 32.90±4.49 W/kg; p>0.05, women: from 26.36±4.73 to 27.25±4.44 W/kg; p>0.05). Post-exercise urine samples revealed proteinuria (60.9% of cases in men and 66.7% in women), leukocyturia (men?=?43.5% and women?=?50.0%) and erythrocyturia (men?=?50.0% and women?=?21.7%). Conclusions Despite a moderate sweat rate, badminton players adequately hydrated during a game and thus the dehydration attained was low. The badminton match did not cause muscle fatigue but it significantly increased the prevalence of proteinuria, leukocyturia and erythrocyturia. PMID:22666396

Abián-Vicén, Javier; Del Coso, Juan; González-Millán, Cristina; Salinero, Juan José; Abián, Pablo

2012-01-01

313

Gunion - Nevada`s most innovative geothermal food dehydration facility  

SciTech Connect

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.

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

1995-12-31

314

Preparation of poly(vinyl alcohol)-sodium alginate hollow-fiber composite membranes and pervaporation dehydration characterization of aqueous alcohol mixtures  

Microsoft Academic Search

A hollow-fiber composite membrane, poly(vinyl alcohol) (PVA)-sodium alginate (SA) blend, supported by a polysulfone (PS) hollow-fiber ultrafiltration membrane, was prepared for pervaporation dehydration from isoproanol, n-butanol, tert-butanol and ethanol aqueous solutions. The compatibility of PVA–SA was characterized by FTIR and SEM; the mechanism of the cross-linking reaction is discussed. The results of pervaporation showed that high selectivity and promising permeability

Y. Q. Dong; L. Zhang; J. N. Shen; M. Y. Song; H. L. Chen

2006-01-01

315

Energetic consequences of repeated and prolonged dehydration in the Antarctic midge, Belgica antarctica.  

PubMed

Larvae 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-tolerant insects studied, surviving up to 70% loss of its body water. While previous studies have characterized the physiological effects of a single bout of dehydration, in nature larvae are likely to experience multiple bouts of dehydration throughout their lifetime. Thus, we examined the physiological consequences of repeated dehydration and compared results to larvae exposed to a single, prolonged period of dehydration. For the repeated dehydration experiment, larvae were exposed to 1-5 cycles of 24 h dehydration at 75% RH followed by 24 h rehydration. Each bout of dehydration resulted in 30-40% loss of body water, with a concomitant 2- to 3-fold increase in body fluid osmolality. While nearly 100% of larvae survived a single bout of dehydration, <65% of larvae survived five such cycles. Larvae subjected to multiple bouts of dehydration also experienced severe depletion of carbohydrate energy reserves; glycogen and trehalose content decreased with each successive cycle, with larvae losing 89% and 48% of their glycogen and trehalose, respectively, after five cycles of dehydration/rehydration. Larvae exposed to prolonged dehydration (99% RH for 10d) had 26% less water, 43% less glycogen, and 27% less lipid content than controls, but did not experience any mortality. Thus, both repeated and prolonged dehydration results in substantial energetic costs that are likely to negatively impact fitness. PMID:22133311

Teets, Nicholas M; Kawarasaki, Yuta; Lee, Richard E; Denlinger, David L

2012-04-01

316

Glucose and fructose decomposition in subcritical and supercritical water: Detailed reaction pathway, mechanisms, and kinetics  

SciTech Connect

The authors are developing a new catalyst-free process of cellulose decomposition in supercritical water. In their initial study on the cellulose decomposition in supercritical water, the main products of cellulose decomposition were found to be oligomers of glucose (cellobiose, cellotriose, etc.) and glucose at short residence times (400 C, 25 MPa, 0.05 s). The kinetics of glucose at these conditions can be useful in understanding the reaction pathways of cellulose. Experiments were performed on the products of glucose decomposition at short residence times to elucidate the reaction pathways and evaluate kinetics of glucose and fructose decomposition in sub- and supercritical water. The conditions were a temperature of 300--400 C and pressure of 25--40 MPa for extremely short residence times between 0.02 and 2 s. The products of glucose decomposition were fructose, a product of isomerization, 1,6-anhydroglucose, a product of dehydration, and erythrose and glyceraldehyde, products of C-C bond cleavage. Fructose underwent reactions similar to glucose except that it did not form 1,6-anhydroglucose and isomerization to glucose is negligible. The mechanism for the products formed from C-C bond cleavage could be explained by reverse aldol condensation and the double-bond rule of the respective enediols formed during the Lobry de Bruyn Alberda van Ekenstein transformation. The differential equations resulting from the proposed pathways were fit to experimental results to obtain the kinetic rate constants.

Kabyemela, B.M.; Adschiri, T.; Malaluan, R.M.; Arai, K. [Tohoku Univ., Sendai (Japan). Dept. of Chemical Engineering] [Tohoku Univ., Sendai (Japan). Dept. of Chemical Engineering

1999-08-01

317

Coupled deformation and dehydration processes in smectite-rich sediments constrained by laboratory experiments  

NASA Astrophysics Data System (ADS)

Subduction zones play a central role in the geological activity of the earth which is expressed as devastating events such as earthquakes, tsunamis and explosive volcanism. Many processes that lead to such catastrophic behavior are driven by fluids, which in turn affect the rock mechanical behavior. The kinetic reaction of hydrous smectite to illite is widely accepted as a fluid source in subduction zone forearcs that also affects the mechanical state of subduction zone sediments. The released fluids are characterized by low-chlorinity and high volatile content. Also, previous workers demonstrated in uniaxial deformation tests that smectite partially dehydrates with increasing effective stress. To shed light on this process we performed uniaxial deformation experiments on smectite-rich samples from the Nankai and Costa Rica subduction zones. Experiments were conducted at temperatures of up to 100°C under constant rate of strain and effective stresses of up to ~100MPa. Fluids expelled during the experiments were analyzed for major and minor element content. The fluids are characterized by fluid-freshening and increasing volatile content that starts at ~1.3MPa effective stress. During the course of the experiments the smectite interlayer water content decreases from 27 wt-% to 20 wt-%. The released interlayer water comprises up to 17% of the total fluid volume released from the consolidating sediment. The onset of fluid freshening is characterized by a change in deformation behavior of the samples. The porosity decrease with increasing effective stress is smaller at effective stresses greater 1.3MPa. We propose that dehydration of the low permeable smectite leads to excess pore pressures in the sample, which causes a load transfer from the solid phase to the pore fluid.

Huepers, Andre; Kopf, Achim J.

2013-04-01

318

Entrapment and condensation of DNA in neutral reverse micelles.  

PubMed Central

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

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

2002-01-01

319

U.S. will require glycol dehydrator emission control  

SciTech Connect

Recent or proposed changes in federal an state clean air laws and regulations will affect the operation of glycol dehydration units used to remove water vapor from natural gas. These laws and regulations will limit the amount of aromatic hydrocarbons, such as benzene, toluene, ethyl benzene and xylene (BTEX) and volatile organic compounds (VOCs), that may be emitted into their from the glycol regenerator still vent. This article presents an overview of new laws and regulations, as well as process control systems that may be used to control and reduce the BTEX and VOC emissions. Flare, incineration units, aerial coolers, recycle units and the efficient R-BTEX process are described.

Sivalls, C.R. [Sivalls, Inc., Odessa, TX (United States)

1995-11-01

320

Mild Dehydration and Cycling Performance During 5-Kilometer Hill Climbing  

PubMed Central

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

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

2013-01-01

321

Observational Evidence for Incomplete Dehydration in the TTL  

NASA Astrophysics Data System (ADS)

The tropical tropopause layer (TTL) is the primary gateway for entry of air into the stratosphere from the troposphere. Because the coldest region of the TTL is found above the western Pacific, dehydration of stratosphere-bound air parcels in this region by deposition of water vapour to form ice crystals is therefore a key process controlling the humidity of the stratospheric overworld. Strong correlations between stratospheric humidity and TTL temperatures on intra-annual and interannual timescales have demonstrated that this mechanism is largely correct, and that the majority of the variability in stratospheric humidity can be attributed to TTL temperature fluctuations. What is less clear is exactly how air is finally dehydrated on its passage through the TTL, setting the mixing ratio of water vapour entering the stratosphere. Cirrus microphysics is complex, and there are multiple reasons to expect that air parcels containing relative humidity with respect to ice (RHi) greater than 100% may frequently pass the through the Lagrangian dry point and enter the stratosphere. For example, in the absence of appropriate particles to act as heterogeneous nuclei for ice crystal formation, RHi exceeding 160% at TTL temperatures is required for clouds to initially form and remove water from the gas phase. Once cirrus clouds form, if ice crystal concentrations are low (~100 / liter or less), the time for thermodynamic gas/particle equilibrium to be achieved can be hours and is potentially slower than passage through the coldest regions. Here we present aircraft measurements from the NASA Global Hawk Airborne Tropical Tropopause Experiment (ATTREX-2) of relative humidity, ice water content, and ice crystal concentrations from the central and eastern Pacific TTL in February - March 2013. This dataset provides unprecedented high-quality observations of the key parameters required to test theoretical descriptions of dehydration in the TTL. During ATTREX-2, the cirrus clouds encountered most frequently had low ice crystal concentrations. While the few clouds encountered with high ice crystal concentrations contained RHi very close to 100%, the more common thin clouds had higher average and more variable RHi. A number of these observations show supersaturated air near 380K potential temperature, the typical cold point tropopause. ATTREX-2 achieved a significant number of flight hours sampling air in this key region of the atmosphere. These observations provide evidence that suggest that the average entry value of water vapour into the stratosphere may be somewhat supersaturated due to the typical low concentrations of ice crystals in the dehydrating cirrus clouds. Additional measurements in the western Pacific during winter 2014 (ATTREX-3) will significantly improve the statistics of these observations.

Rollins, D. W.; Thornberry, T. D.; Gao, R.; Lawson, P.; Bui, T. V.; Fahey, D. W.

2013-12-01

322

Dehydration induced loss of photosynthesis in Arabidopsis leaves during senescence is accompanied by the reversible enhancement in the activity of cell wall ?-glucosidase.  

PubMed

The physiology of loss of photosynthetic production of sugar and the consequent cellular sugar reprogramming during senescence of leaves experiencing environmental stress largely remains unclear. We have shown that leaf senescence in Arabidopsis thaliana causes a significant reduction in the rate of oxygen evolution and net photosynthetic rate (Pn). The decline in photosynthesis is further aggravated by dehydration. During dehydration, primary photochemical reaction of thylakoids and net photosynthesis decrease in parallel with the increase in water deficit. Senescence induced loss in photosynthesis is accompanied by a significant increase in the activity of cell wall hydrolyzing enzyme such as ?-glucosidase associated with cell wall catabolism. The activity of this enzyme is further enhanced when the senescing leaves experience dehydration stress. It is possible that both senescence and stress separately or in combination result in the loss in photosynthesis which could be a signal for an enhancement in the activity of ?-glucosidase that breaks down cell wall polysaccharides to sugar to sustain respiration for metabolic activities of plants experiencing stress. Thus dehydration response of cell wall hydrolases of senescing leaves is considered as plants' strategy to have cell wall polysaccharides as an alternative energy source for completion of energy requiring senescence process, stress survival and maintenance of recovery potential of energy deficit cells in the background of loss in photosynthesis. Withdrawal of stress (rehydration) distinctly exhibits recovery of photosynthesis and suppression of enzyme activity. Retention of the signaling for sugar reprogramming through breakdown of cell wall polysaccharides in the senescing leaves exposed to severe drought stress suggests that senescing leaves like mature ones possess potential for stress recovery. The precise mechanism of stress adaptation of senescing leaves is yet to be known. A significant accumulation of anthocyanin and flavonoids may be an indicator of stress adaptation of senescing leaves. In addition, stress induced enhancement of nonphotochemical quenching (NPQ), a stress protection provision in green plants, also suggests the potential of the leaves to develop adaptational mechanism to counter the dehydration stress. PMID:24793323

Patro, Lichita; Mohapatra, Pranab Kishor; Biswal, Udaya Chand; Biswal, Basanti

2014-08-01

323

Condensed Matter Nuclear Science  

NASA Astrophysics Data System (ADS)

Preface -- 1. General. Progress in condensed matter nuclear science / A. Takahashi. Summary of ICCF-12 / X. Z. Li. Overview of light water/hydrogen-based low-energy nuclear reactions / G. H. Miley and P. J. Shrestha -- 2. Excess heat and He detection. Development of "DS-reactor" as the practical reactor of "cold fusion" based on the "DS-cell" with "DS-cathode" / Y. Arata and Y.-C. Zhang. Progress in excess of power experiments with electrochemical loading of deuterium in palladium / V. Violante ... [et al.]. Anomalous energy generation during conventional electrolysis / T. Mizuno and Y. Toriyabe. "Excess heat" induced by deuterium flux in palladium film / B. Liu ... [et al.]. Abnormal excess heat observed during Mizuno-type experiments / J.-F. Fauvarque, P. P. Clauzon and G. J.-M. Lallevé. Seebeck envelope calorimetry with a Pd|D[symbol]O + H[symbol]SO[symbol] electrolytic cell / W.-S. Zhang, J. Dash and Q. Wang. Observation and investigation of nuclear fusion and self-induced electric discharges in liquids / A. I. Koldamasov ... [et al.]. Description of a sensitive seebeck calorimeter used for cold fusion studies / E. Storms. Some recent results at ENEA / M. Apicella ... [et al.]. Heat measurement during plasma electrolysis / K. Iizumi ... [et al.]. Effect of an additive on thermal output during electrolysis of heavy water with a palladium cathode / Q. Wang and J. Dash. Thermal analysis of calorimetric systems / L. D'Aulerio ... [et al.]. Surface plasmons and low-energy nuclear reactions triggering / E. Castagna ... [et al.]. Production method for violent TCB jet plasma from cavity / F. Amini. New results and an ongoing excess heat controversy / L. Kowalski ... [et al.] -- 3. Transmutation. Observation of surface distribution of products by X-ray fluorescence spectrometry during D[symbol] gas permeation through Pd Complexes / Y. Iwamura ... [et al.]. Discharge experiment using Pd/CaO/Pd multi-layered cathode / S. Narita ... [et al.]. Producing transmutation element on multi-layered Pd sample by deuterium permeation / H. Yamada ... [et al.]. Experimental observation and combined investigation of high-performance fusion of iron-region isotopes in optimal growing microbiological associations / V. I. Vysotskii ... [et al.]. Research into low-energy nuclear reactions in cathode sample solid with production of excess heat, stable and radioactive impurity nuclides / A. B. Karabut. Influence of parameters of the glow discharge on change of structure and the isotope composition of the cathode materials / I. B. Savvatimova and D. V. Gavritenkov. Elemental analysis of palladium electrodes after Pd/Pd light water critical electrolysis / Y. Toriyabe ... [et al.]. Progress on the study of isotopic composition in metallic thin films undergone to electrochemical loading of hydrogen / M. Apicella ... [et al.]. In situ accelerator analyses of palladium complex under deuterium permeation / A. Kitamura ... [et al.]. High-resolution mass spectrum for deuterium (hydrogen) gas permeating palladium film / Q. M. Wei ... [et al.]. ICP-MS analysis of electrodes and electrolytes after HNO[symbol]/H[symbol]O electrolysis / S. Taniguchi ... [et al.]. The Italy-Japan project - fundamental research on cold transmutation process for treatment of nuclear wastes / A. Takahashi, F. Celani and Y. Iwamura -- 4. Nuclear physics approach. Reproducible nuclear emissions from Pd/PdO:Dx heterostructure during controlled exothermic deuterium desorption / A. G. Lipson ... [et al.]. Correct identification of energetic alpha and proton tracks in experiments on CR-39 charged particle detection during hydrogen desorption from Pd/PdO:H[symbol] heterostructure / A. S. Roussetski ... [et al.]. Intense non-linear soft X-ray emission from a hydride target during pulsed D bombardment / G. H. Miley ... [et al.]. Enhancement of first wall damage in ITER type TOKAMAK due to LENR effects / A. G. Lipson, G. H. Miley and H. Momota. Generation of DD-reactions in a ferroelectric KD[symbol]PO[symbol] single crystal during transition

Takahashi, Akito; Ota, Ken-Ichiro; Iwamura, Yashuhiro

324

Classic Organic Reactions  

NSDL National Science Digital Library

Despite the fact that the Classic Organic Reactions Page was designed for commercial purposes, to demonstrate the capabilities of ChemPen chemical structure drawing software for Windows, the page offers a useful resource for chemistry students and professionals. The creator of this page, and author and proprietor of ChemPen, Dr. Hilton Evans, has cited the literature for each reaction. The site contains drawings for over 300 alphabetically listed classic organic reactions. The list begins with the Acetoacetic Ester Condensation and ends with the Zinke-Suhl Reaction.

325

Polariton Condensate Transistor Switch  

E-print Network

A polariton condensate transistor switch is realized through optical excitation of a microcavity ridge with two beams. The ballistically ejected polaritons from a condensate formed at the source are gated using the 20 times weaker second beam to switch on and off the flux of polaritons. In the absence of the gate beam the small built-in detuning creates potential landscape in which ejected polaritons are channelled toward the end of the ridge where they condense. The low loss photon-like propagation combined with strong nonlinearities associated with their excitonic component makes polariton based transistors particularly attractive for the implementation of all-optical integrated circuits.

Gao, T; Liew, T C H; Tsintzos, S I; Stavrinidis, G; Deligeorgis, G; Hatzopoulos, Z; Savvidis, P G

2012-01-01

326

Electrolyte vapor condenser  

DOEpatents

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.

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

1983-02-08

327

Electrolyte vapor condenser  

DOEpatents

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.

Sederquist, Richard A. (Newington, CT); Szydlowski, Donald F. (East Hartford, CT); Sawyer, Richard D. (Canton, CT)

1983-01-01

328

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)

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.

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

2013-10-01

329

Framework for Understanding LENR Processes, Using Conventional Condensed Matter Physics  

Microsoft Academic Search

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

Scott R. Chubb

330

Addition polymers from 1,4,5,8-tetrahydro-1,4;5,8-diepoxyanthracene and Bis-dienes. 2: Evidence for thermal dehydration occurring in the cure process  

NASA Technical Reports Server (NTRS)

Diels-Alder cycloaddition copolymers from 1,4,5,8-tetrahydro-1,4;5,8-diepoxyanthracene and anthracene end-capped polyimide oligomers appear, by thermogravimetric analysis (TGA), to undergo dehydration at elevated temperatures. This would produce thermally stable pentiptycene units along the polymer backbone, and render the polymers incapable of unzipping through a retro-Diels-Alder pathway. High resolution solid 13C nuclear magnetic resonance (NMR) of one formulation of the polymer system before and after heating at elevated temperatures, shows this to indeed be the case. NMR spectra of solid samples of the polymer before and after heating correlated well with those of the parent pentiptycene model compound before and after acid-catalyzed dehydration. Isothermal gravimetric analyses and viscosities of the polymer before and after heat treatment support dehydration as a mechanism for the cure reaction.

Meador, Mary Ann B.; Olshavsky, Michael A.; Meador, Michael A.; Ahn, Myong-Ku

1988-01-01

331

Osmotic dehydration of fruits and vegetables: a review.  

PubMed

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

Yadav, Ashok Kumar; Singh, Satya Vir

2014-09-01

332

Lidocaine elimination and monoethylglycinexylidide formation in the dehydrated camel.  

PubMed

The elimination kinetics and the formation of the monoethylglycinexylidide (MEGX), a major metabolite of lidocaine, were studied in camels deprived of water for 14 days. The study was conducted on four camels in a crossover design. Lidocaine was administered intravenously at a dose of 1 mg/kg to adult female camels when water was given ad libitum (stage 1) and to the same camels after 14 days of dehydration. Blood samples were taken up to 6 h after dosing. Serum lidocaine and MEGX levels were analysed by polarization fluorescence immunoassay. The elimination profiles of lidocaine and the formation of the metabolite MEGX in the two phases of the study were essentially identical. No difference in any pharmacokinetic parameter was noticed between normally hydrated and water-deprived camels. It is thus concluded that dehydration does not affect the cytochrome P450 isozymes involved in degradation of lidocaine to MEGX nor does it affect the hepatic blood flow, which is a major determinant in the clearance of lidocaine. The very low clearance of lidocaine in the camel in comparison with other ruminant or monogastric mammals may be associated with the camel's ability to survive drought in the desert. PMID:8789697

Ben-Zvi, Z; Goldin, G; Van Creveld, C; Yagil, R

1995-12-01

333

Assessing diarrhoea-induced dehydration at the community level.  

PubMed

A community based study of children under 5 years of age in Nampula, Mozambique, assessed children with diarrhoea for the 12 signs and symptoms of dehydration listed in the World Health Organization's Diarrhoea Treatment Chart and for the additional indicators of observed thirst and reported fever. The point prevalence of diarrhoea was 13.1%. The signs and symptoms of dehydration reported by carers were compared with signs detected on physical examination at the time of the interview. The presence of four or more stools, a history of drinking either more or less than usual, and reported fever in the preceding 24 h had the highest sensitivities. Individual symptoms with the highest specificity were decreased urine output, vomiting, and the passing of 10 or more stools during the 24 h preceding the interview. The combination of fever or vomiting had a sensitivity of 68.3% and a specificity of 55.9%, whereas a combination of vomiting or drinking more than usual or fever had a sensitivity of 87.8% and a specificity of 34.1%. These findings are compared with the results of similar studies conducted in different clinical and cultural settings. PMID:1880822

Herman, E; Cutts, F; Soares, A

1991-08-01

334

Severe hypercalcaemia and colon ischaemia: dehydration as an unusual cause?  

PubMed

Hypercalcaemia is an emergency with severe consequences. Dehydration can be an uncommon cause of hypercalcaemia, as seen in this case. A 63-year-old woman with type 2 diabetes mellitus, hypothyroidism and osteoporosis, was admitted to the emergency room with abdominal distension and vomiting for 24?h. Initial evaluation was Hg 18.5?g/dL, Htc 56.2%, creatinine 2?mg/dL, metabolic acidaemia, lactate 8.3?mmol/L, anion gap 19, total Ca(2+) 17.7?mg/dL and PO4+ 6.6?mg/dL. CT revealed colonic distension without obstruction or ischaemia. Renal replacement therapy and pamidronate were initiated. The patient's clinical condition deteriorated with septic shock in the context of toxic megacolon and she underwent an emergency subtotal colectomy (10?kg). Hypercalcaemia was corrected in 24?h with aggressive fluid replacement (8?L NaCl 0.9% first 12?h), with a reduction of total Ca(2+) to 8.2?mg/dL. Other causes of hypercalcaemia were excluded. 'Hypercalcaemic crisis' secondary to severe acute dehydration is not mentioned in the literature. PMID:25809432

Fernandes, Liliana Gil; Ferreira, Nuno Ribeiro; Cardiga, Rosa; Póvoa, Pedro

2015-01-01

335

Calculation of dehydration absorbers based on improved phase equilibrium data  

SciTech Connect

Dehydration using triethylene glycol (TEG) as an absorbent, is a standard process for natural gas treating. New and more accurate TEG/water equilibrium data have been measured between 1980 and 1990. However, this has not influenced much on the design methods of dehydration absorbers. Inaccurate equilibrium data have been extensively used in design calculations. When using data from a common source like Worley, an overall bubble cap tray efficiency between 25--40% has normally been recommended. This has resulted in a quite satisfactory and consistent design method. It is obvious that newer equilibrium data (Herskowitz, Parrish, Bestani) are more accurate. However, to achieve an improved design method, column efficiencies consistent with the new equilibrium data must be recommended. New equilibrium data have been correlated to an activity coefficient model for the liquid phase and combined with an equation of state for the gas phase. Performance data from the North Sea offshore platform Gullfaks C (drying 4--5 MMscmd) have been measured. The bubble cap column has been simulated, and the tray efficiency has been adjusted to fit the performance data. Tray efficiencies calculated with new equilibrium data are higher than 50%. Calculated tray efficiency values are dependent on the equilibrium data used. There are still uncertainties in equilibrium data for the TEC/water/natural gas system. When using accurate equilibrium data, an overall bubble cap tray efficiency of 40--50% and a Murphree efficiency of 55--70% can be expected at normal absorption conditions.

Oi, L.E.

1999-07-01

336

Organic Chemistry 51B -Winter 2013 Organic Chemistry Peer Tutoring Program Chemistry 51B Reactions List  

E-print Network

. Preparation of alkoxides (Bronsted-Lowry acid-base reaction) Need a strong base NaOH cannot deprotonate attack via SN2 mechanism Reactions of Alcohols 1. Dehydration to form alkenes a. Using strong acid Can mechanism Work with strong nucleophile b. Elimination E2 mechanism Work with strong base Reactions

Rose, Michael R.

337

Trifluorophenylethylidene Condensation Polyimides  

NASA Technical Reports Server (NTRS)

Report describes synthesis and properties of trifluorophenylethylidene (3F) condensation polyimides. Properties of these new polymers make suitable thermal-control coatings, interlayer dielectrics in advanced wafer chips, and electronic-multilevel-interconnection layers.

Alston, William B.; Gratz, Roy F.

1987-01-01

338

THE COLOR GLASS CONDENSATE.  

SciTech Connect

The Color Glass Condensate is a state of high density gluonic matter which controls the high energy limit of hadronic interactions. Its properties are important for the initial conditions for matter produced at RHIC.

MCLERRAN,L.

2001-08-26

339

Mechanism of dropwise condensation  

E-print Network

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 ...

Umur, Aydin

1963-01-01

340

Measure Guideline: Evaporative Condensers  

SciTech Connect

The purpose of this measure guideline on evaporative condensers is to provide information on a cost-effective solution for energy and demand savings in homes with cooling loads. This is a prescriptive approach that outlines selection criteria, design and installation procedures, and operation and maintenance best practices. This document has been prepared to provide a process for properly designing, installing, and maintaining evaporative condenser systems as well as understanding the benefits, costs, and tradeoffs.

German, A.; Dakin, B.; Hoeschele, M.

2012-03-01

341

Open Problems in $?$ Particle Condensation  

E-print Network

$\\alpha$ particle condensation is a novel state in nuclear systems. We briefly review the present status on the study of $\\alpha$ particle condensation and address the open problems in this research field: $\\alpha$ particle condensation in heavier systems other than the Hoyle state, linear chain and $\\alpha$ particle rings, Hoyle-analogue states with extra neutrons, $\\alpha$ particle condensation related to astrophysics, etc.

Y. Funaki; M. Girod; H. Horiuchi; G. Roepke; P. Schuck; A. Tohsaki; T. Yamada

2010-03-05

342

Condensate dark matter stars  

SciTech Connect

We investigate the structure and stability properties of compact astrophysical objects that may be formed from the Bose-Einstein condensation of dark matter. Once the critical temperature of a boson gas is less than the critical temperature, a Bose-Einstein Condensation process can always take place during the cosmic history of the universe. Therefore we model the dark matter inside the star as a Bose-Einstein condensate. In the condensate dark matter star model, the dark matter equation of state can be described by a polytropic equation of state, with polytropic index equal to one. We derive the basic general relativistic equations describing the equilibrium structure of the condensate dark matter star with spherically symmetric static geometry. The structure equations of the condensate dark matter stars are studied numerically. The critical mass and radius of the dark matter star are given by M{sub crit} ? 2(l{sub a}/1fm){sup 1/2}(m{sub ?}/1 GeV){sup ?3/2}M{sub s}un and R{sub crit} ? 1.1 × 10{sup 6}(l{sub a}/1 fm){sup 1/2}(m{sub ?}/1 GeV){sup ?3/2} cm respectively, where l{sub a} and m{sub ?} are the scattering length and the mass of dark matter particle, respectively.

Li, X.Y.; Harko, T.; Cheng, K.S., E-mail: lixinyu@hku.hk, E-mail: harko@hkucc.hku.hk, E-mail: hrspksc@hkucc.hku.hk [Department of Physics and Center for Theoretical and Computational Physics, The University of Hong Kong, Pok Fu Lam Road, Hong Kong (China)

2012-06-01

343

The Usefulness of Clinical and Laboratory Parameters for Predicting Severity of Dehydration in Children with Acute Gastroenteritis  

PubMed Central

ABSTRACT Background: An accurate assessment of the degree of dehydration in infants and children is important for proper decision-making and treatment. This emphasizes the need for laboratory tests to improve the accuracy of clinical assessment of dehydration. The aim of this study was to assess the relationship between clinical and laboratory parameters in the assessment of dehydration. Methods: We evaluated prospectively 200 children aged 1 month to 5 years who presented with diarrhea, vomiting or both. Dehydration assessment was done following a known clinical scheme. Results: We enrolled in the study 200 children (57.5% were male). The mean age was 15.62±9.03 months, with more than half those studied being under 24 months old. Overall, 46.5% (93) had mild dehydration, 34% (68) had moderate dehydration, 5.5% (11) had severe dehydration whereas, 14% (28) had no dehydration. Patients historical clinical variables in all dehydration groups did not differ significantly regarding age, sex, fever, frequency of vomiting, duration of diarrhea and vomiting, while there was a trend toward severe dehydration in children with more frequent diarrhea (p=0.004). Serum urea and creatinine cannot discriminate between mild and moderate dehydration but they showed a good specificity for severe dehydration of 99% and 100% respectively. Serum bicarbonates and base excess decreased significantly with a degree of dehydration and can discriminate between all dehydration groups (P<0.001). Conclusion: Blood gases were useful to diagnose the degree of dehydration status among children presenting with acute gastroenteritis. Serum urea and creatinine were the most specific tests for severe dehydration diagnosis. Historical clinical patterns apart from frequency of diarrhea did not correlate with dehydration status. Further studies are needed to validate our results. PMID:25568559

Hoxha, Teuta Faik; Azemi, Mehmedali; Avdiu, Muharrem; Ismaili-jaha, Vlora; Grajqevci, Violeta; Petrela, Ela

2014-01-01

344

Dehydration-induced cross tolerance of Belgica antarctica larvae to cold and heat is facilitated by trehalose accumulation.  

PubMed

Larvae of the Antarctic midge, Belgica antarctica (Diptera: Chironomidae), are frequently exposed to dehydrating conditions on the Antarctic Peninsula. In this study, we examined how rates and levels of dehydration alter heat and cold tolerance and how these relate to levels of trehalose within the insect. When dehydrated, larvae tolerated cold and heat stress more effectively, although resistance to cold was more pronounced than heat resistance. Slow dehydration was more effective than rapid dehydration in increasing temperature tolerance. Severe dehydration (50% reduction in water content) caused a much greater increase in temperature tolerance than did mild dehydration (e.g. 10% water loss). Larvae severely dehydrated at a slow rate (98% RH) were more temperature tolerant than those dehydrated quickly (0 or 75% RH). These results indicate that the slower dehydration rate allows the larvae to more effectively respond to reduced water levels and that physiological adjustments to desiccation provide cross tolerance to cold and heat. Levels of trehalose increased during dehydration and are likely a major factor increasing subsequent cold and heat resistance. This hypothesis was also supported by experimental results showing that injection of trehalose enhanced resistance to temperature stress and dehydration. We conclude that changes in temperature tolerance in B. antarctica are linked to the rate and severity of dehydration and that trehalose elevation is a probable mechanism enhancing this form of cross tolerance. PMID:19141330

Benoit, Joshua B; Lopez-Martinez, Giancarlo; Elnitsky, Michael A; Lee, Richard E; Denlinger, David L

2009-04-01

345

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

Microsoft Academic Search

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

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

2008-01-01

346

Clinical assessment of dehydration in older people admitted to hospital What are the strongest indicators?  

Microsoft Academic Search

Due to an absence of published primary data, this study explores dehydration prevalence and the change in physiological parameters frequently used to assess dehydration (fluid deficit) in older hospitalized people, as no standard measurement method exists. This observational long- itudinal cohort study recruited 43 people aged 60 years or over, voluntarily admitted to a tertiary teaching hospital's Geriatric and Rehabilitation

Angela Vivanti; Keren Harvey; Susan Ash; Diana Battistutta

347

The “dehydrated” lumbar intervertebral disk on MR, its anatomy, biochemistry and biomechanics  

Microsoft Academic Search

# Springer-Verlag 2011 MR imaging of the lumbar spine often reveals disks with lower than normal signal in the nucleus pulposus without decreased disk height or abnormal contours of the annulus fibrosus. These are often referred to as “dehydrated”, “desiccated” or “dark” disks. The clinical significance of dehydrated disks may not be generally known. Official reports of MR images tend

Vitcor Haughton

2011-01-01

348

Control of Polyphenol Oxidase Activity in Banana Slices During Osmotic Dehydration  

Microsoft Academic Search

The purpose of this study was to determine the effect of sodium metabisulfite and 4-hexylresorcinol on polyphenol oxidase (PPO) activity change in banana slices during osmotic dehydration in sucrose syrup.From a previous study only three osmotic dehydration conditions were selected as the most adequate due to color change but also where PPO residual activity was still present after osmotic drying:

K. N. Waliszewski; V. T. Pardio; S. L. Ovando

2007-01-01

349

Selection and Evaluation of Demulsifier Applied to Aging Crude Oil Dehydration  

Microsoft Academic Search

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.

Wei Lixin; Wang Jinxiu; Wang Zhihua; Hou Jincai

2010-01-01

350

Dehydration among Long-Term Care Elderly Patients with Oropharyngeal Dysphagia  

Microsoft Academic Search

Introduction: Long-term care (LTC) residents, especially the orally fed with dysphagia, are prone to dehydration. The clinical consequences of dehydration are critical. The validity of the common laboratory parameters of hydration status is far from being absolute, especially so in the elderly. However, combinations of these indices are more reliable. Objective: Assessment of hydration status among elderly LTC residents with

A. Leibovitz; Y. Baumoehl; E. Lubart; A. Yaina; N. Platinovitz; R. Segal

2007-01-01

351

Dehydration of 2-Methyl-1-Cyclohexanol: New Findings from a Popular Undergraduate Laboratory Experiment  

ERIC Educational Resources Information Center

The mineral acid-catalyzed dehydration of 2-methyl-1-cyclohexanol has been a popular laboratory exercise in second-year organic chemistry for several decades. The dehydration experiment is often performed by organic chemistry students to illustrate Zaitsev's rule. However, sensitive analytical techniques reveal that the results do not entirely…

Friesen, J. Brent; Schretzman, Robert

2011-01-01

352

HIGH PERMEABILITY MEMBRANES FOR THE DEHYDRATION OF LOW WATER CONTENT ETHANOL BY PERVAPORATION  

EPA Science Inventory

Energy efficient dehydration of low water content ethanol is a challenge for the sustainable production of fuel-grade ethanol. Pervaporative membrane dehydration using a recently developed hydrophilic polymer membrane formulation consisting of a cross-linked mixture of poly(allyl...

353

Influence of osmotic dehydration and freezing on the volatile profile of kiwi fruit  

Microsoft Academic Search

The effect of osmotic dehydration on the volatile fraction of kiwi fruit was studied, as well as the effect of freezing and frozen storage. Osmotic treatments were carried out in sucrose solutions until the kiwi fruit reached 30°Brix, at atmospheric pressure (OD) and by applying a vacuum pulse (PVOD), by using 45 and 65°Brix sucrose. Volatile compounds of fresh, dehydrated

P Talens; I Escriche; N Mart??nez-Navarrete; A Chiralt

2003-01-01

354

Skeletal muscle volume following dehydration induced by exercise in heat  

PubMed Central

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?

2012-01-01

355

TTL Dehydration Characterized by SOWER Observations over the Pacific  

NASA Astrophysics Data System (ADS)

The Soundings of Ozone and Water in the Equatorial Region (SOWER) has been accumulating observational evidences of atmospheric dehydration taking place for the air parcels advected horizontally in the Tropical Tropopause Layer (TTL). This paper discusses the nature of TTL dehydration using the dataset obtained since initiation in 1998. The cold-trap dehydration associated with the quasi-horizontal advection (Holton and Gettelman, 2001) effectively functions between 360 K and 380 K isentropes leading to the mean water mixing ratio of 1.9 × 0.6 ppmv on arrival at 380 K after slow diabatic assent, while some moistening takes place before the air parcel reaches 400 K. An example from individual soundings shows 80 % supersaturation in relative humidity with respect to ice (RHice) in subvisible cirrus clouds located near the cold point tropopause (CPT) at the temperature around 180 K (Hasebe et al., 2013). The water budget for individual air parcels has been estimated by searching for the opportunity of repeated sampling of the same air parcel (water vapor match) in the TTL (Inai et al., this meeting). Simultaneous observations by lidar and Optical Particle Counters near the CPT reveal cirrus clouds within the aerosol layer composed of liquid phase aqueous sulfuric acid particles. The characteristics of the TTL cirrus cloud particles are discussed by Sakurai et al. (this meeting). The differences in the observed water content are brought about by the temperature history of the air parcels described by the dynamical field as well as the climatological location of observation station. Inai et al. (2012) found that the difference of RHice inside TTL cirrus between the two stations strongly depend on the phase of MJO disturbances. Further analysis shows that the water mixing ratios on 355 K and 360 K are lower (higher) to the east (west) relative to the temperature maximum associated with TTL Kelvin waves. Back trajectory analyses suggest that the difference is brought about by the associated dynamical field (so-called Matsuno-Gill pattern) leading to the exposure of lower (higher) temperature for the air parcels advected to the west (east) in the easterly (westerly) phase of Kelvin waves, which is consistent with the notion by Eguchi and Shiotani (2004). The results from extended analyses will be presented together with more discussions.

Hasebe, F.; Shiotani, M.; Fujiwara, M.; Shibata, T.; Inai, Y.

2013-12-01

356

Mechanisms to reduce dehydration stress in larvae of the Antarctic midge, Belgica antarctica.  

PubMed

The Antarctic midge, Belgica antarctica, is exposed to frequent periods of dehydration during its prolonged larval development in the cold and dry Antarctic environment. In this study, we determined the water requirements of the larvae and the mechanisms it exploits to reduce the stress of drying. Larvae lost water at an exceptionally high rate (>10%/h) and tolerated losing a high portion (>70%) of their water content. Larvae were unable to absorb water from subsaturated water vapor (< or = 0.98 a(v)) to replenish their water stores, thus this midge relies exclusively on the intake of liquid water to increase its pool of body water and maintain water balance. To reduce dehydration stress, the midge employed a variety of mechanisms. Behaviorally, the larvae suppressed water loss by clustering. In response to slow dehydration, glycerol concentration increased 2-fold and trehalose concentration increased 3-fold, responses that are known to decrease the rate of water loss and increase dehydration tolerance. No changes in the mass of cuticular lipids occurred in response to desiccation, but the observed shift to longer hydrocarbons likely contributes to reduced water loss as the larvae dehydrate. As the larvae dehydrated, their oxygen consumption rate dropped, resulting in a reduction of water loss by respiration. Lastly, one bout of slow dehydration also enhanced the larva's ability to survive subsequent dehydration, suggesting that the larvae have the capacity for drought acclimation. Thus, these hydrophilic midge larvae prevent dehydration by multiple mechanisms that collectively reduce the water loss rate and increase dehydration tolerance. PMID:17543329

Benoit, Joshua B; Lopez-Martinez, Giancarlo; Michaud, M Robert; Elnitsky, Michael A; Lee, Richard E; Denlinger, David L

2007-07-01

357

An organ-specific role for ethylene in rose petal expansion during dehydration and rehydration  

PubMed Central

Dehydration is a major factor resulting in huge loss from cut flowers during transportation. In the present study, dehydration inhibited petal cell expansion and resulted in irregular flowers in cut roses, mimicking ethylene-treated flowers. Among the five floral organs, dehydration substantially elevated ethylene production in the sepals, whilst rehydration caused rapid and elevated ethylene levels in the gynoecia and sepals. Among the five ethylene biosynthetic enzyme genes (RhACS1–5), expression of RhACS1 and RhACS2 was induced by dehydration and rehydration in the two floral organs. Silencing both RhACS1 and RhACS2 significantly suppressed dehydration- and rehydration-induced ethylene in the sepals and gynoecia. This weakened the inhibitory effect of dehydration on petal cell expansion. ?-glucuronidase activity driven by both the RhACS1 and RhACS2 promoters was dramatically induced in the sepals, pistil, and stamens, but not in the petals of transgenic Arabidopsis. This further supports the organ-specific induction of these two genes. Among the five rose ethylene receptor genes (RhETR1–5), expression of RhETR3 was predominantly induced by dehydration and rehydration in the petals. RhETR3 silencing clearly aggravated the inhibitory effect of dehydration on petal cell expansion. However, no significant difference in the effect between RhETR3-silenced flowers and RhETR-genes-silenced flowers was observed. Furthermore, RhETR-genes silencing extensively altered the expression of 21 cell expansion-related downstream genes in response to ethylene. These results suggest that induction of ethylene biosynthesis by dehydration proceeds in an organ-specific manner, indicating that ethylene can function as a mediator in dehydration-caused inhibition of cell expansion in rose petals. PMID:23599274

Liu, Daofeng; Liu, Xiaojing; Gao, Junping

2013-01-01

358

Dehydration of oil waste emulsions by means of flocculants  

SciTech Connect

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.

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

1995-05-01

359

Characterization of dehydration-induced luminescence of kaolinite  

NASA Technical Reports Server (NTRS)

The dehydration-induced luminescence of a colloidal kaolinite is investigated experimentally, with particular attention given to the effect of various treatments on the luminescence characteristics. It is found that the total photon count of the emitted light is linearly related to the film thickness up to a thickness of 30 microns; mechanical stress in the form of grinding increases the photon output and produces extensive changes in the emission kinetics. A direct check of the emission wavelength dependence (by using color filters) indicates that roughly 75 percent of the emission occurs in the wavelength range below 410 nm. It is also found that incorporation of fluorescent molecules into the kaolinite paste increases the photon output and may indicate the transfer of ultraviolet photons to the fluorescent probe.

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

1985-01-01

360

Mesoporous siliconiobium phosphate as a pure Brønsted acid catalyst with excellent performance for the dehydration of glycerol to acrolein.  

PubMed

The development of solid acid catalysts that contain a high density of Brønsted acid sites with suitable acidity, as well as a long lifetime, is one of great challenges for the efficient dehydration of glycerol to acrolein. Herein, we report on a mesoporous siliconiobium phosphate (NbPSi-0.5) composite, which is a promising solid Brønsted acid that is a potential candidate for such a high-performance catalyst. A variety of characterization results confirm that NbPSi-0.5 contains nearly pure Brønsted acid sites and has well-defined large mesopores. In addition, NbPSi-0.5 contains a similar amount of acid sites and exhibits weaker acidity than that of the highly acidic niobium phosphate and HZSM-5 zeolite. NbPSi-0.5 is quite stable and has a high activity for the dehydration of glycerol. The stability of NbPSi-0.5 is about three times higher than that of the reported catalyst. The significantly enhanced catalytic performance of NbPSi-0.5 can be attributed to 1) nearly pure Brønsted acidity, which suppresses side reactions that lead to coke formation; 2) a significant reduction of pore blocking due to the mesopores; and 3) a decrease in the amount and oxidation temperature of coke. PMID:23132784

Choi, Youngbo; Park, Dae Sung; Yun, Hyeong Jin; Baek, Jayeon; Yun, Danim; Yi, Jongheop

2012-12-01

361

A critical evaluation of crustal dehydration as the cause of an overpressured and weak San Andreas Fault  

USGS Publications Warehouse

Many plate boundary faults, including the San Andreas Fault, appear to slip at unexpectedly low shear stress. One long-standing explanation for a "weak" San Andreas Fault is that fluid release by dehydration reactions during regional metamorphism generates elevated fluid pressures that are localized within the fault, reducing the effective normal stress. We evaluate this hypothesis by calculating realistic fluid production rates for the San Andreas Fault system, and incorporating them into 2-D fluid flow models. Our results show that for a wide range of permeability distributions, fluid sources from crustal dehydration are too small and short-lived to generate, sustain, or localize fluid pressures in the fault sufficient to explain its apparent mechanical weakness. This suggests that alternative mechanisms, possibly acting locally within the fault zone, such as shear compaction or thermal pressurization, may be necessary to explain a weak San Andreas Fault. More generally, our results demonstrate the difficulty of localizing large fluid pressures generated by regional processes within near-vertical fault zones. ?? 2009 Elsevier B.V.

Fulton, P.M.; Saffer, D.M.; Bekins, B.A.

2009-01-01

362

Mitotic chromatin condensation in vitro using somatic cell extracts and nuclei with variable levels of endogenous topoisomerase II  

Microsoft Academic Search

We report the development of a new method for producing mitotic extracts from tissue cul- ture cells. These extracts reproducibly promote the condensation of chromatin in vitro when incubated with purified interphase nuclei. This condensation reaction is not species specific, since nuclei from chicken, human, and hamster cell lines all undergo chromatin condensation upon incubation with the ex- tract. We

Edgar R. Wood; William C. Earnshaw

1990-01-01

363

Reaction network of steam reforming of ethanol over Ni-based catalysts  

Microsoft Academic Search

The reaction of steam reforming of ethanol over nickel catalysts supported on ?-Al2O3, La2O3, and La2O3\\/?-Al2O3 is investigated employing transient and steady-state techniques. It is found that ethanol interacts strongly with alumina on the surface of which it is dehydrated at low temperatures, and less strongly with lanthana on the surface of which it is both dehydrogenated and dehydrated. Cracking

Athanasios N. Fatsikostas; Xenophon E. Verykios

2004-01-01

364

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

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

365

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

PubMed

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

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

2012-01-01

366

Simple Simulations of DNA Condensation  

SciTech Connect

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.

STEVENS,MARK J.

2000-07-12

367

Simple simulations of DNA condensation.  

PubMed Central

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 phenomenon 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. PMID:11159388

Stevens, M J

2001-01-01

368

Evaporation, Condensation, and Precipitation  

NSDL National Science Digital Library

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 ...

Miss Brown

2009-10-21

369

Condensation phenomena in plasmonics  

NASA Astrophysics Data System (ADS)

We study arrays of plasmonic nanoparticles combined with quantum emitters, quantum plasmonic lattices, as a platform for room-temperature studies of quantum many-body physics. We outline a theory to describe surface plasmon-polariton distributions when they are coupled to externally pumped molecules. The possibility of tailoring the dispersion in plasmonic lattices allows realization of a variety of distributions, including the Bose-Einstein distribution as in photon condensation [Klaers et al., Nature (London) 468, 545 (2010), 10.1038/nature09567]. We show that the presence of losses can relax some of the standard dimensionality restrictions for condensation.

Martikainen, J.-P.; Heikkinen, M. O. J.; Törmä, P.

2014-11-01

370

Containment condensing heat transfer  

NASA Astrophysics Data System (ADS)

A mechanistic heat transfer model that is valid for large scale containment heat sinks was presented. The model development is based on the determination that the condensation is controlled by mass diffusion through the vapor-air boundary layer, and the application of the classic Reynolds' analog to formulate expressions for the transfer of heat and mass based on hydrodynamic measurements of the momentum transfer. As a result, the analysis depends on the quantification of the shear stress (momentum transfer) at the interface between the condensate film and the vapor-air boundary layer. In addition, the currently used Tagami and Uchida test observations and their range of applicability are explained.

Gido, R. G.; Koestel, A.

371

Galaxies as condensates  

E-print Network

A novel interpretation of MOND is presented. For galactic data, in addition to Newtonian acceleration, there is an attractive acceleration peaking at Milgrom's parameter a_0. The peak lies within experimental error where a_0 = cH_0/2\\pi and H_0 is the present-time value of the Hubble constant. This peaking may be understood in terms of quantum mechanical mixing between Newtonian gravitation and the condensation mechanism. There are five pointers towards galaxies being Fermi-Dirac condensates.

D. V. Bugg

2012-12-21

372

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

373

Wet fractionation of forage to reduce energy requirements of dehydration. Final technical report  

SciTech Connect

The Valley Dehydrating Company of Atwood, Colorado, was founded in 1952 to dehydrate alfalfa. Subsequently, it was realized that the rapidly escalating cost of natural gas, burned to provide heat for the dehydration of the alfalfa, would make the traditional process of direct dehydration uneconomical. As an alternative, the use of green crop fractionation in combination with waste heat recovery from the main dryer was investigated. In the wet, or green crop fractionation process, freshly cut alfalfa is brought to the processing site where it is first macerated to rupture the plant cells and then is pressed to remove as much juice as possible. The fiber fraction from the pressing contains only about half as much moisture as the original alfalfa; and thus, can be dehydrated at a much lower cost. The juice which contains plant proteins and lipids as well as a variety of soluble components, is heated to above 80/sup 0/C in order to coagulate the protein. When this material is separated from the residual liquid and dried a high protein, high xanthophyll product (Pro-Xan) results. The remaining solubles are concentrated, using the waste heat from the main dryer to yield a molasses-like product. Instead of the one product, (dehydrated alfalfa) produced by the traditional process, green crop fractionation produces three: dehydrated pressed alfalfa, leaf nutrient concentrate, and molasses.

Not Available

1981-01-01

374

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

PubMed Central

Summary Dehydration may alter vocal fold viscoelastic properties, which may hamper 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 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 releasing. This calls more attention to the modeling of vocal folds in micromechanics modeling. 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. The results will contribute to a better understanding of the basic biomechanics of voice production and ultimately will help establish objective dehydration and phonotrauma criteria. PMID:22483778

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

2012-01-01

375

Comparative transcriptome analysis of differentially expressed genes in foxtail millet (Setaria italica L.) during dehydration stress.  

PubMed

Dehydration stress is one of the most important abiotic stresses that adversely influence crop growth and productivity. With the aim to understand the molecular mechanisms underlying dehydration stress tolerance in foxtail millet (Setaria italica L.), a drought tolerant crop, we examined its transcriptome changes at two time points (early and late) of dehydration stress. Two suppression subtractive hybridization (SSH) forward libraries were constructed from 21-day old seedlings of tolerant cv. Prasad at 0.5 and 6h PEG-induced dehydration stress. A total of 327 unique ESTs were identified from both libraries and were classified into 11 different categories according to their putative functions. The plant response against dehydration stress was complex, representing major transcripts involved in metabolism, stress, signaling, transcription regulation, translation and proteolysis. By Reverse Northern (RN) technique we identified the differential expression pattern of 327 transcripts, 86 (about 26%) of which showed > or = 1.7-fold induction. Further the obtained results were validated by quantitative real-time PCR (qRT-PCR) to have a comparative expression profiling of randomly chosen 9 up-regulated transcripts (> or =2.5 fold induction) between cv. Prasad (tolerant) and cv. Lepakshi (sensitive) upon dehydration stress. These transcripts showed a differential expression pattern in both cultivars at different time points of stress treatment as analyzed by qRT-PCR. The possible relationship of the identified transcripts with dehydration tolerance mechanism is discussed. PMID:20171162

Lata, Charu; Sahu, Pranav Pankaj; Prasad, Manoj

2010-03-19

376

The thermodynamics of arsenates, selenites, and sulfates in the oxidation zone of sulfide ores: VIII. Field of thermal stability of synthetic analog of chalcomenite, its dehydration and dissociation  

NASA Astrophysics Data System (ADS)

The objective of this paper is to study the thermal stability of the synthetic analog of chalcomenite, CuSeO3 · 2H2O, and its dehydration and dissociation, in an experimental context. The study has been carried out by a comprehensive application of thermogravimetry (TG), differential scanning calorimetry (DSC), and high-temperature X-ray diffraction at a temperature range of 25-600°C. It has been established that CuSeO3 · 2H2O dehydrates at 202-264°C in three stages corresponding to the formation of intermediate CuSeO3 · 2H2O and CuSeO3 · 1/3H2O hydrate phases. At 480-595°C anhydrous CuSeO3 breaks down into CuO and SeO2 via the formation of a Cu4O(SeO3)3 phase. Enthalpies of the reactions at each stage of the CuSeO3 · 2H2O dehydration and CuSeO3 dissociation have been determined and their kinetic analysis has been carried out.

Fokina, E. L.; Klimova, E. V.; Charykova, M. V.; Krivovichev, V. G.; Platonova, N. V.; Semenova, V. V.; Depmeier, W.

2014-12-01

377

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

PubMed

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

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

2014-05-01

378

Dehydration Induced Faulting in Eclogite at High Pressure: A Mechanism for Intermediate-Focus Earthquakes  

NASA Astrophysics Data System (ADS)

Embrittlement induced by fluid release during dehydration reactions has been proposed to explain both intermediate focus (70-300 km) earthquakes and deep-focus (>300 km) earthquakes in subduction zones. In addition to dehydration of hydrous phases (e.g. lawsonite, phengite, antigorite), in principle hydroxyl-bearing nominally anhydrous minerals (olivine, pyroxene, garnet) within the subducting lithosphere also can provide a source for fluid release in subducting slabs. We have performed deformation experiments at 3 GPa pressure on a reconstituted natural eclogite that contains a significant OH concentration in both pyroxene and garnet. Fluid-free samples of this material exhibit exsolution of H2O and grain-boundary melting at temperatures between the H2O-saturated and dry solidi. Deformation of these samples leads to brittle failure under conditions where the total fluid present is very small and the material is strong. At higher temperatures, where the flow stress is significantly reduced by larger amounts of melt, faulting does not occur. At temperatures below the wet solidus, no fluid is produced and faulting does not occur, even though specimens are very strong under such conditions. Within the faulting regime, the failure strength of the eclogite is not temperature sensitive. Microstructural observation of faulted specimens revealed ultra-thin glass films along grain boundaries and within abundant Mode I microcracks. Fault gouge contains small amounts of glass and angular fragments of garnet and pyroxene that appear to have a fractal size distribution. Addition of water to deformation experiments performed is generated by the added H2O to reduce the flow stress to below the fracture stress. At moderate temperatures in subduction zones, phengite remains stable to very high pressures. Thus, small amounts of phengite stable at lower pressures could provide a source of H2O that could progressively dissolve into pyroxene and garnet with increasing pressure and thereby be carried to greater depths where it could exsolve and trigger earthquakes or where it could be incorporated into the circulating mantle.

Zhang, J.; Green, H. W.; Bozhilov, K. N.; Jin, Z.

2002-12-01

379

The role of hypothalamic ingestive behavior controllers in generating dehydration anorexia: a Fos mapping study.  

PubMed

Giving rats 2.5% saline to drink for 3-5 days simply and reliably generates anorexia. Despite having the neurochemical and hormonal markers of negative energy balance, dehydrated anorexic rats show a marked suppression of spontaneous food intake, as well as the feeding that is usually stimulated by overnight starvation or a 2-deoxy-d-glucose (2DG) challenge. These observations are consistent with a dehydration-dependent inhibition of the core circuitry that controls feeding. We hypothesize that this inhibition is directed at those neurons in the paraventricular nucleus and lateral hypothalamic area that constitute the hypothalamic "behavior controller" for feeding rather than their afferent inputs from the arcuate nucleus or hindbrain that convey critical feeding-related sensory information. To test this hypothesis, we mapped and quantified the Fos-immunoreactive response to 2DG in control and dehydrated rats drinking 2.5% saline. Our rationale was that regions showing an attenuated Fos response to 2DG in dehydrated animals would be strong candidates as the targets of dehydration-induced suppression of 2DG feeding. We found that the Fos response to combined dehydration and 2DG was attenuated only in the lateral hypothalamic area, with dehydration alone increasing Fos in the lateral part of the paraventricular nucleus. In the arcuate nucleus and those regions of the hindbrain that provide afferent inputs critical for the feeding response to 2DG, the Fos response to 2DG was unaffected by dehydration. Therefore, dehydration appears to target the lateral hypothalamic area and possibly the lateral part of the paraventricular nucleus to suppress the feeding response to 2DG. PMID:18667712

Salter-Venzon, Dawna; Watts, Alan G

2008-10-01

380

Analytical modeling of water condensation in condensing heat exchanger  

Microsoft Academic Search

An analytical model of heat and mass transfer processes in a flue gas condensing heat exchanger system was developed to predict the heat transferred from flue gas to cooling water and the condensation rate of water vapor in the flue gas. Flue gas exit temperature, cooling water outlet temperature, water vapor mole fraction, and condensation rate of water vapor were

Kwangkook Jeong; Michael J. Kessen; Harun Bilirgen; Edward K. Levy

2010-01-01

381

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...

382

Molecular and structural preservation of dehydrated bio-tissue for THz spectroscopy  

NASA Astrophysics Data System (ADS)

Terahertz transmission through freshly excised biological tissue is limited by the tissue's high water content. Tissue fixation methods that remove water, such as fixation in Formalin, destroy the structural information of proteins hence are not suitable for THz applications. Dehydration is one possible method for revealing the tissue's underlying molecular structure and components. In this study, we measured the THz responses over time of dehydrating fresh, necrotic and lyophilized rat tissue. Our results show that as expected, THz absorption increases dramatically with drying and tissue freshness can be maintained through lyophilization. Dehydrated biological tissue with retained molecular structure can be useful for future laser-based THz wave molecular analysis.

Png, Gretel M.; Choi, Jin Wook; Guest, Ian; Ng, Brian W.-H.; Mickan, Samuel P.; Abbott, Derek; Zhang, Xi-Cheng

2007-12-01

383

Exciton-polariton condensates  

NASA Astrophysics Data System (ADS)

Recently a new type of system exhibiting spontaneous coherence has emerged--the exciton-polariton condensate. Exciton-polaritons (or polaritons for short) are bosonic quasiparticles that exist inside semiconductor microcavities, consisting of a superposition of an exciton and a cavity photon. Above a threshold density the polaritons macroscopically occupy the same quantum state, forming a condensate. The polaritons have a lifetime that is typically comparable to or shorter than thermalization times, giving them an inherently non-equilibrium nature. Nevertheless, they exhibit many of the features that would be expected of equilibrium Bose-Einstein condensates (BECs). The non-equilibrium nature of the system raises fundamental questions as to what it means for a system to be a BEC, and introduces new physics beyond that seen in other macroscopically coherent systems. In this review we focus on several physical phenomena exhibited by exciton-polariton condensates. In particular, we examine topics such as the difference between a polariton BEC, a polariton laser and a photon laser, as well as physical phenomena such as superfluidity, vortex formation, and Berezinskii-Kosterlitz-Thouless and Bardeen-Cooper-Schrieffer physics. We also discuss the physics and applications of engineered polariton structures.

Byrnes, Tim; Kim, Na Young; Yamamoto, Yoshihisa

2014-11-01

384

The Color Glass Condensate  

E-print Network

We provide a broad overview of the theoretical status and phenomenological applications of the Color Glass Condensate effective field theory describing universal properties of saturated gluons in hadron wavefunctions that are extracted from deeply inelastic scattering and hadron-hadron collision experiments at high energies.

F. Gelis; E. Iancu; J. Jalilian-Marian; R. Venugopalan

2010-02-01

385

Re-Condensation  

E-print Network

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...

Bhatia, P.; Kozman, T.

2004-01-01

386

The Newcastle condensation survey  

Microsoft Academic Search

The Housing Management Committee of the City of Newcastle wished to find some basis on which to establish priorities for remedial and up-grading work on existing houses. With the assistance of the Director of Housing three surveys were commissioned, two of which were specialist ones concentrating on over 600 dwellings sited in an area known to have condensation problems.The first

G. K. Preston; C. J. Stephens; G. W. Brundrett

1981-01-01

387

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...

388

Asymmetric condensed dark matter  

E-print Network

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.

Anthony Aguirre; Alberto Diez-Tejedor

2015-02-25

389

Condenser biofouling control  

SciTech Connect

A compilation of most of the papers presented at the March 1979 symposium in Atlanta, GA on condensor biofouling control is presented. The following aspects of power plant condenser biofouling are discussed: effects on power plant equipment and operations; cost impact; biofilm formation; corrosive effects; control practices using chlorine or bromine chlorides, and the dechlorination of discharges of chlorinated coolants. (LCL)

Garey, J.F.; Jorden, R.M.; Aitken, A.H.; Burton, D.T.; Gray, R.H. (eds.)

1980-01-01

390

Using Incongruent Equilibrium Hydration Reactions to Model Latter-Stage Crystallization in Plutons: Examples from the Bell Island Tonalite, Alaska  

Microsoft Academic Search

Models using hydration crystallization reactions (the reverse of dehydration melting reactions such as amph + qtz = px + melt) for the Bell Island pluton define incongruent equilibrium crystallization paths from hydrous + melt + pyroxene + Fe-Ti oxides + calcic andesine (30%-50% solid) to a solid tonalite consisting mostly of hornblende, lower temperature end of Bowen's discontinuous reaction series

Maria Luisa Crawford

2005-01-01

391

Glucose reversion reaction kinetics.  

PubMed

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

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

2010-05-26

392

Bonding by Hydroxide-Catalyzed Hydration and Dehydration  

NASA Technical Reports Server (NTRS)

A simple, inexpensive method for bonding solid objects exploits hydroxide-catalyzed hydration and dehydration to form silicate-like networks in thin surface and interfacial layers between the objects. The method can be practiced at room temperature or over a wide range of temperatures. The method was developed especially to enable the formation of precise, reliable bonds between precise optical components. The bonds thus formed exhibit the precision and transparency of bonds formed by the conventional optical-contact method and the strength and reliability of high-temperature frit bonds. The method also lends itself to numerous non-optical applications in which there are requirements for precise bonds and/or requirements for bonds, whether precise or imprecise, that can reliably withstand severe environmental conditions. Categories of such non-optical applications include forming composite materials, coating substrates, forming laminate structures, and preparing objects of defined geometry and composition. The method is applicable to materials that either (1) can form silicate-like networks in the sense that they have silicate-like molecular structures that are extensible into silicate-like networks or (2) can be chemically linked to silicate-like networks by means of hydroxide-catalyzed hydration and dehydration. When hydrated, a material of either type features surface hydroxyl (-OH) groups. In this method, a silicate-like network that bonds two substrates can be formed either by a bonding material alone or by the bonding material together with material from either or both of the substrates. Typically, an aqueous hydroxide bonding solution is dispensed and allowed to flow between the mating surfaces by capillary action. If the surface figures of the substrates do not match precisely, bonding could be improved by including a filling material in the bonding solution. Preferably, the filling material should include at least one ingredient that can be hydrated to have exposed hydroxyl groups and that can be chemically linked, by hydroxide catalysis, to a silicate-like network. The silicate-like network could be generated in situ from the filling material and/or substrate material, or could be originally present in the bonding material.

Gwo, Dz-Hung

2008-01-01

393

Nanostructure-induced DNA condensation  

NASA Astrophysics Data System (ADS)

The control of the DNA condensation process is essential for compaction of DNA in chromatin, as well as for biological applications such as nonviral gene therapy. This review endeavours to reflect the progress of investigations on DNA condensation effects of nanostructure-based condensing agents (such as nanoparticles, nanotubes, cationic polymer and peptide agents) observed by using atomic force microscopy (AFM) and other techniques. The environmental effects on structural characteristics of nanostructure-induced DNA condensates are also discussed.

Zhou, Ting; Llizo, Axel; Wang, Chen; Xu, Guiying; Yang, Yanlian

2013-08-01

394

PVC waterproofing membranes and alkali-aggregated reaction in dams  

SciTech Connect

A waterproofing polyvinylchloride (PVC) based geocomposite was installed on two dams subject to alkali-aggregate reaction, to eliminate water intrusion and to protect the facing from further deterioration. The installation system allows drainage of the infiltrated water, thus accomplishing dehydration of the dam body. On one dam, the membrane also provided protection for future slot cutting.

Scuero, A.M. [C.A.R.P.I. Technologies SA, Lugano (Czech Republic)

1995-12-31

395

Onion and garlic dehydration in the San Emidio Desert, Nevada  

SciTech Connect

Integrated Ingredients dedicated their new onion and garlic processing plant on May 25th. {open_quotes}Grunion{close_quotes} as the new community of 72 employees has been labeled, is located just south of Empire and Gerlach and about 100 miles north of Reno, Nevada. The plant, run by Integrated Ingredients (based in Alameda, CA), is a division of Burns Philp Food, Inc., which owns brands such as Spice Islands, Durkee-French and Fleischmann`s. This plant gives the company the ability to produce its own products for industrial and consumer markets instead of purchasing them. The plant was located in the San Emidio Desert at the edge of the vast Black Rock Desert and the Great Basin to take advantage of the high temperature geothermal resource (approximately 270{degrees}F). The resource is also used by the OESI/AMOR II 3.6 MW binary plant about a mile south of the dehydration plant and a gold heap leaching operation just to the north of the plant (Wind Mt. mine operated by AMAX). In addition to the geothermal energy, the high desert is an ideal location for onion and garlic processing because the cold winters kill damaging microbes. Dry winters and summers also help.

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

1994-07-01

396

The development of the predisposition to dehydration questionnaire.  

PubMed

The role played by hydration in general health and well-being is an emerging public health issue, yet there are few tools available to monitor its status in large populations. The aim was therefore to develop a questionnaire that assesses individual differences in the tendency to lose body fluid in a warm environment and hence become dehydrated. Fifty-three subjects sat in a room at 30°C for four hours and changes in mood and measures of hydration were monitored. There were marked individual differences in the loss of body mass that differed from 0.24% to 2.39%. Females who reported habitually drinking a lot had more water in their diet and at baseline the osmolality of urine was lower. After being subject to heat, those who reported habitually drinking more produced more urine, had a lower urine osmolality at the end of the study, and overall more body mass was lost. Females who reported that they responded badly to heat were more confused, unsure and depressed after four hours at 30°C. In males those reporting that they habitually drank to a greater extent had more water in the diet, and also those who dealt badly with heat habitually drank more. It was concluded that particularly in females, questionnaire measures were able to predict changes in hydration that result from a warm environment. PMID:25477317

Benton, David; Young, Hayley; Jenkins, Kimberley

2015-04-01

397

Dehydrating and Sterilizing Wastes Using Supercritical CO2  

NASA Technical Reports Server (NTRS)

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

Brown, Ian J.

2006-01-01

398

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

SciTech Connect

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.

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

399

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...

400

Mixed Matrix Silicone and Fluorosilicone/Zeolite 4A Membranes for Ethanol Dehydration by Pervaporation  

EPA Science Inventory

The ability of homogeneous and mixed matrix membranes prepared using standard silicone rubber, poly(dimethylsiloxane) (PDMS), and fluorosilicone rubber, poly(trifluoropropylmethylsiloxane) (PTFPMS), to dehydrate ethanol by pervaporation was evaluated. Although PDMS is generally c...

401

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...

402

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 ...

403

Monitoring the dehydration of collagen by time-domain terahertz transmission measurements  

Microsoft Academic Search

We measured the change of the terahertz-frequency dielectric properties in collagen hydrated in saline spanning hypo-normal, normal and hyper-normal physiological conditions, during a 24-hour dehydration period in-vitro.

Peter M. Corridon; Ingrid Wilke

2007-01-01

404

A NOVEL HYDROPHILIC POLYMER MEMBRANE FOR THE DEHYDRATION OF ORGANIC SOLVENTS  

EPA Science Inventory

Novel hydrophilic polymer membranes based on polyallylamine ydrochloride- polyvinylalcohol are developed. The high selectivity and flux characteristics of these membranes for the dehydration of organic solvents are evaluated using pervaporation technology and are found to be ver...

405

Microwave-enhanced dehydration and solvent washing purification of penicillin G sulfoxide.  

PubMed

In the present study, a new microwave-enhanced dehydration and solvent washing purification of penicillin G sulfoxide technique has been developed. The results show that microwave irradiation can dehydrate penicillin G sulfoxide from a water content of 14-26 to below 0.5% in 40-60 min in N2 or air. After washing with ethyl acetate to remove impurities and residual water, the penicillin G sulfoxide can be used to synthesize cephalosporanic acid. The recovery of cephalosporanic acid was equal to and the purity of cephalosporanic acid was higher by 2% than that of the current dehydration technique. FTIR spectroscopy was used to study the process of microwave-enhanced dehydration and solvent washing purification of penicillin G sulfoxide. PMID:11376965

Pan, X; Liu, H; An, Z; Wang, J; Niu, G

2001-06-01

406

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

NASA Technical Reports Server (NTRS)

Dehydration of more than 0.5 ppmv water was observed between 18 and 19 km (theta = 450-465 K) at the edge of the Arctic polar vortex on February 1, 1996. More than half the reactive nitrogen (NOy) had also been removed, with layers of enhanced NOy 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 (approx. 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 of theta is estimated to have been dehydrated in this event.

Hintsa, E. J.; Newman, P. A.; Jonsson, H. H.; Webster, C. R.; May, R. D.; Herman, R. L.; Lait, L. R.; Schoerberl, M. R.; Elkins, J. W.; Wamsley, P. R.

1998-01-01

407

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

NASA Technical Reports Server (NTRS)

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.

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

408

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

NASA Technical Reports Server (NTRS)

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.

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

409

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

NASA Technical Reports Server (NTRS)

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.

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

410

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

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

Tetsu Kogiso; Yoshiyuki Tatsumi; Satoshi Nakano

1997-01-01

411

Mass transfer during osmotic dehydration of pineapple: considering Fickian diffusion in cubical configuration  

Microsoft Academic Search

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

N. K Rastogi; K. S. M. S Raghavarao

2004-01-01

412

Demulsification of water-in-crude oil emulsions by a continuous electrostatic dehydrator  

Microsoft Academic Search

The demulsification rates of water-in-crude oil emulsion in high AC fields were investigated under various conditions by using a model dehydrator. A continuous electrostatic dehydrator was constructed using a glass vessel of 6.5 cm diameter and 10 cm height equipped with a copper electrode and a perforated plate. The separation rate of water from the simulated crude oil increased along with the

Byoung-Yun Kim; Jun Hyuk Moon; Tae-Hyun Sung; Seung-Man Yang; Jong-Duk Kim

2002-01-01

413

Formation of Linear Polyenes in Thermal Dehydration of Polyvinyl Alcohol, Catalyzed by Phosphotungstic Acid  

NASA Astrophysics Data System (ADS)

In order to obtain linear polyenes in polyvinyl alcohol films via acid-catalyzed thermal dehydration of the polyvinyl alcohol, we used phosphotungstic acid as the catalyst: a safe and heat-stable solid chemical compound. We established that phosphotungstic acid, introduced as solid nanoparticles into polyvinyl alcohol films, is a more effective dehydration catalyst than hydrochloric acid, since in contrast to HCl it does not evaporate from the film during heat treatment.

Tretinnikov, O. N.; Sushko, N. I.

2015-01-01

414

Dehydration, rehydration, and overhydration alter patterns of gene expression in the Antarctic midge, Belgica antarctica.  

PubMed

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, osmotic stress from ocean spray and drying conditions due to wind and intense sunlight. Using suppressive subtractive hybridization (SSH), we obtained clones that were potentially responsive to dehydration and then used northern blots to evaluate the gene's responsiveness to different dehydration rates and hydration states. Among the genes most responsive to changes in the hydration state were those encoding heat shock proteins (smHsp, Hsp70, Hsp90), antioxidants (superoxide dismutase, catalase), detoxification (metallothionein, cytochrome p450), genes involved in altering cell membranes (fatty acid desaturase, phospholipase A2 activating protein, fatty acyl CoA desaturase) and the cytoskeleton (actin, muscle-specific actin), and several additional genes including a zinc-finger protein, pacifastin and VATPase. Among the three types of dehydration evaluated, fast dehydration elicited the strongest response (more genes, higher expression), followed by cryoprotective dehydration and slow dehydration. During rehydration most, but not all, genes that were expressed during dehydration continued to be expressed; fatty acid desaturase was the only gene to be uniquely upregulated in response to rehydration. All genes examined, except VATPase, were upregulated in response to overhydration. The midge larvae are thus responding quickly to water loss and gain by expressing genes that encode proteins contributing to maintenance of proper protein function, protection and overall cell homeostasis during times of osmotic flux, a challenge that is particularly acute in this Antarctic environment. PMID:19125254

Lopez-Martinez, Giancarlo; Benoit, Joshua B; Rinehart, Joseph P; Elnitsky, Michael A; Lee, Richard E; Denlinger, David L

2009-05-01

415

Swelling and dehydration characteristics of transition metal ion-exchanged taeniolites  

Microsoft Academic Search

The swelling and dehydration characteristics of Mn2+, Ni2+, Cu2+ and Zn2+ ion-substituted taeniolites with the exchange ratios of 85% and 78% have been investigated by high-temperature X-ray diffractometry, thermogravimetry-differential thermal analysis and calorimetry. The transition metal forms are the swelling states with two water-molecule layers at room temperature and a relative humidity of 70%, and their dehydration processes to the

Michihiro Miyake; Hiroyuki Yamaguchi; Takashi Suzuki

1990-01-01

416

The dehydration and rehydration characteristics of the seeded breadfruit or breadnut seed  

Microsoft Academic Search

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

L. Harrynanan; C. K. Sankat

2008-01-01

417

Sorghum Silages and Dehydrated Alfalfa Leaf Meal as Sources of Carotene in Beef Cattle Fattening Rations.  

E-print Network

[Blank Page in Original Bulletin] Carotene as contained in dehydrated alfalfa meal was apparently better utilized for vitamin A activity than carotene in either sweet sorghum or grain sorghum silage. Carotene as contained in the two sorghum... silages seemed to be about equally utilized. Sweet sorghum silage such as sumac or red ~p cane silage contained approximately twice as much car- tene as the grain sorghum silages such as kafir, milo, and egari silage. The dehydrated alfalfa leaf meal...

Jones, John H.

1944-01-01

418

Using poly( N,N-dimethylaminoethyl methacrylate)\\/polyacrylonitrile composite membranes for gas dehydration and humidification  

Microsoft Academic Search

The transport of water vapor through a composite membrane consisting of hydrophilic poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) as the active layer and polyacrylonitrile (PAN) as the substrate was investigated, and the performance of the membrane for gas dehydration and humidification applications was evaluated. For gas dehydration, methane\\/water vapor mixtures were used as feed and vacuum was applied on the downstream side. The

Jennifer Runhong Du; Li Liu; Amit Chakma; Xianshe Feng

2010-01-01

419

Nature, nurture, nutrition: Interdisciplinary programs to address the prevention of malnutrition and dehydration  

Microsoft Academic Search

Malnutrition and dehydration are common problems in nursing home patients. One explanation for this may be the large number\\u000a of patients requiring feeding assistance. The Dysphagia Team at the Department of Veterans Affairs Medical Center in Miami,\\u000a Florida served as the primary source in the expansion of a nutritionally supportive environment to assist in the prevention\\u000a of malnutrition and dehydration

Nan D. Musson; Jean Kincaid; Pat Ryan; Betty Glussman; Litha Varone; Nydia Gamarra; Reba Wilson; William Reefe; Michael Silverman

1990-01-01

420

Osteoblasts response to allogenic and xenogenic solvent dehydrated cancellous bone in vitro  

Microsoft Academic Search

The present in vitro study investigates the cellular interaction of primary human osteoblasts with human and bovine solvent dehydrated cancellous bone (SDCB) discs. These are bio-implants from solvent dehydrated, gamma-irradiated preserved human and bovine cancellous bone, pre-treated to remove all cells, genetic components and water soluble proteins. Primary human osteoblasts were harvested from cancellous chips of trauma patients undergoing osteosynthesis

Omana A Trentz; Simon P Hoerstrup; Li K Sun; Lukas Bestmann; Andreas Platz; Otmar L Trentz

2003-01-01

421

Photosynthetic parameters and carbon reserves of a resurrection plant Reaumuria soongorica during dehydration and rehydration  

Microsoft Academic Search

The effects of dehydration and subsequent rehydration on photosynthetic parameters and carbon reserves were investigated in\\u000a the resurrection plant Reaumuria soongorica. Dehydration was imposed by withholding water and covering plants with a PVC sheet when it rained, over a period of 53 days,\\u000a by which time all leaves had been shed. Thereafter, plants were watered at 7-day intervals. The diurnal course

Danghui Xu; Peixi Su; Renyi Zhang; Honglin Li; Liang Zhao; Gang Wang

2010-01-01

422

Condenser performance monitoring and cleaning  

SciTech Connect

The main condenser at Ginna Station was retubed from admiralty brass to 316 stainless steel. A condenser performance monitoring spreadsheet was developed using EPRI guidelines after fouling was discovered. PEPSE computer models were used to determine the power loss and confirm the spreadsheet results. Cleaning of the condenser was performed using plastic scrubbers. Condenser performance improved dramatically following the cleaning. PEPSE, condenser spreadsheet performance, and actual observed plant data correlated well together. The fouling mechanism was determined to be a common lake bacteria and fungus growth which was combined with silt. Chlorination of the circulating water system at the allowable limits is keeping the biofouling under control.

Walden, J.V. [Rochester Gas and Electric, Ontario, NY (United States)

1998-12-31

423

ATG18 and FAB1 Are Involved in Dehydration Stress Tolerance in Saccharomyces cerevisiae.  

PubMed

Recently, different dehydration-based technologies have been evaluated for the purpose of cell and tissue preservation. Although some early results have been promising, they have not satisfied the requirements for large-scale applications. The long experience of using quantitative trait loci (QTLs) with the yeast Saccharomyces cerevisiae has proven to be a good model organism for studying the link between complex phenotypes and DNA variations. Here, we use QTL analysis as a tool for identifying the specific yeast traits involved in dehydration stress tolerance. Three hybrids obtained from stable haploids and sequenced in the Saccharomyces Genome Resequencing Project showed intermediate dehydration tolerance in most cases. The dehydration resistance trait of 96 segregants from each hybrid was quantified. A smooth, continuous distribution of the anhydrobiosis tolerance trait was found, suggesting that this trait is determined by multiple QTLs. Therefore, we carried out a QTL analysis to identify the determinants of this dehydration tolerance trait at the genomic level. Among the genes identified after reciprocal hemizygosity assays, RSM22, ATG18 and DBR1 had not been referenced in previous studies. We report new phenotypes for these genes using a previously validated test. Finally, our data illustrates the power of this approach in the investigation of the complex cell dehydration phenotype. PMID:25803831

López-Martínez, Gema; Margalef-Català, Mar; Salinas, Francisco; Liti, Gianni; Cordero-Otero, Ricardo

2015-01-01

424

Repeated bouts of dehydration deplete nutrient reserves and reduce egg production in the mosquito Culex pipiens  

PubMed Central

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

Benoit, Joshua B.; Patrick, Kevin R.; Desai, Karina; Hardesty, Jeffrey J.; Krause, Tyler B.; Denlinger, David L.

2010-01-01

425

Gene expression changes governing extreme dehydration tolerance in an Antarctic insect  

PubMed Central

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

Teets, Nicholas M.; Peyton, Justin T.; Colinet, Herve; Renault, David; Kelley, Joanna L.; Kawarasaki, Yuta; Lee, Richard E.; Denlinger, David L.

2012-01-01

426

Gene expression changes governing extreme dehydration tolerance in an Antarctic insect.  

PubMed

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

Teets, Nicholas M; Peyton, Justin T; Colinet, Herve; Renault, David; Kelley, Joanna L; Kawarasaki, Yuta; Lee, Richard E; Denlinger, David L

2012-12-11

427

Proteome analysis of Physcomitrella patens exposed to progressive dehydration and rehydration  

PubMed Central

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

Cui, Suxia; Hu, Jia; Guo, Shilei; Wang, Jie; Cheng, Yali; Dang, Xinxing; Wu, Lili; He, Yikun

2012-01-01

428

ATG18 and FAB1 Are Involved in Dehydration Stress Tolerance in Saccharomyces cerevisiae  

PubMed Central

Recently, different dehydration-based technologies have been evaluated for the purpose of cell and tissue preservation. Although some early results have been promising, they have not satisfied the requirements for large-scale applications. The long experience of using quantitative trait loci (QTLs) with the yeast Saccharomyces cerevisiae has proven to be a good model organism for studying the link between complex phenotypes and DNA variations. Here, we use QTL analysis as a tool for identifying the specific yeast traits involved in dehydration stress tolerance. Three hybrids obtained from stable haploids and sequenced in the Saccharomyces Genome Resequencing Project showed intermediate dehydration tolerance in most cases. The dehydration resistance trait of 96 segregants from each hybrid was quantified. A smooth, continuous distribution of the anhydrobiosis tolerance trait was found, suggesting that this trait is determined by multiple QTLs. Therefore, we carried out a QTL analysis to identify the determinants of this dehydration tolerance trait at the genomic level. Among the genes identified after reciprocal hemizygosity assays, RSM22, ATG18 and DBR1 had not been referenced in previous studies. We report new phenotypes for these genes using a previously validated test. Finally, our data illustrates the power of this approach in the investigation of the complex cell dehydration phenotype. PMID:25803831

López-Martínez, Gema; Margalef-Català, Mar; Salinas, Francisco; Liti, Gianni; Cordero-Otero, Ricardo

2015-01-01

429

Na(x)-deficient mice show normal vasopressin response to dehydration.  

PubMed

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

Nagakura, Ayano; Hiyama, Takeshi Y; Noda, Masaharu

2010-03-26

430

Exercise-induced dehydration does not alter time trial or neuromuscular performance.  

PubMed

This study examined the effect of exercise-induced dehydration by ~4% body mass loss on 5-km cycling time trial (TT) performance and neuromuscular drive, independent of hyperthermia. 7 active males were dehydrated on 2 occasions, separated by 7 d. Participants remained dehydrated (DEH, -3.8±0.5%) or were rehydrated (REH, 0.2±0.6%) over 2?h before completing the TT at 18-25?°C, 20-30% relative humidity. Neuromuscular function was determined before dehydration and immediately prior the TT. The TT started at the same core temperature (DEH, 37.3±0.3°C; REH, 37.0±0.2?°C (P>0.05). Neither TT performance (DEH, 7.31±1.5?min; REH, 7.10±1.3?min (P>0.05)) or % voluntary activation were affected by dehydration (DEH, 88.7±6.4%; REH, 90.6±6.1% (P>0.05)). Quadriceps peak torque was significantly elevated in both trials prior to the TT (P<0.05), while a 19% increase in the rate of potentiated peak twitch torque development (P<0.05) was observed in the DEH trial only. All other neuromuscular measures were similar between trials. Short duration TT performance and neuromuscular function are not reduced by dehydration, independent of hyperthermia. PMID:24577860

Stewart, C J; Whyte, D G; Cannon, J; Wickham, J; Marino, F E

2014-08-01

431

Gravity triggered neutrino condensates  

SciTech Connect

In this work we use the Schwinger-Dyson equations to study the possibility that an enhanced gravitational attraction triggers the formation of a right-handed neutrino condensate, inducing dynamical symmetry breaking and generating a Majorana mass for the right-handed neutrino at a scale appropriate for the seesaw mechanism. The composite field formed by the condensate phase could drive an early epoch of inflation. We find that to the lowest order, the theory does not allow dynamical symmetry breaking. Nevertheless, thanks to the large number of matter fields in the model, the suppression by additional powers in G of higher order terms can be compensated, boosting them up to their lowest order counterparts. This way chiral symmetry can be broken dynamically and the infrared mass generated turns out to be in the expected range for a successful seesaw scenario.

Barenboim, Gabriela [Departament de Fisica Teorica and IFIC, Universitat de Valencia-CSIC, E-46100, Burjassot (Spain)

2010-11-01

432

Condensate phase microscopy.  

PubMed

We show that the phase of a Bose-Einstein condensate wave function of ultracold atoms in an optical lattice potential in two dimensions can be detected. The time-of-flight images, obtained in a free expansion of initially trapped atoms, are related to the initial distribution of atomic momenta but the information on the phase is lost. However, the initial atomic cloud is bounded and this information, in addition to the time-of-flight images, is sufficient in order to employ the phase retrieval algorithms. We analyze the phase retrieval methods for model wave functions in a case of a Bose-Einstein condensate in a triangular optical lattice in the presence of artificial gauge fields. PMID:24580464

Kosior, Arkadiusz; Sacha, Krzysztof

2014-01-31

433

Gravitational vacuum condensate stars  

PubMed Central

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

Mazur, Pawel O.; Mottola, Emil

2004-01-01

434

Feshbach-Einstein Condensates  

SciTech Connect

We investigate the phase diagram of a two-species Bose-Hubbard model describing atoms and molecules on a lattice, interacting via a Feshbach resonance. We identify a region where the system exhibits an exotic super-Mott phase and regions with phases characterized by atomic and/or molecular condensates. Our approach is based on a recently developed exact quantum Monte Carlo algorithm: the stochastic Green function algorithm with tunable directionality. We confirm some of the results predicted by mean-field studies, but we also find disagreement with these studies. In particular, we find a phase with an atomic but no molecular condensate, which is missing in all mean-field phase diagrams.

Rousseau, V. G.; Denteneer, P. J. H. [Instituut-Lorentz, LION, Universiteit Leiden, Postbus 9504, 2300 RA Leiden (Netherlands)

2009-01-09

435

Expeditious Pechmann Condensation by Using Biodegradable Cellulose Sulfuric Acid as a Solid Acid Catalyst  

Microsoft Academic Search

A facile synthesis of coumarins was performed in excellent yields via Pechmann condensation by using different type of phenols and ethylacetoacetates under solvent–free media using both conventional method and microwave irradiation in short reaction times is described. The reaction workup is very simple, and the catalyst can be easily separated from the reaction mixture and reused several times in subsequent

B. Suresh Kuarm; J. Venu Madhav; S. Vijaya Laxmi; B. Rajitha; Y. Thirupathi Reddy; P. Narsimha Reddy; Peter A. Crooks

2010-01-01

436

Asymmetric condensed dark matter  

E-print Network

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...

Aguirre, Anthony

2015-01-01

437

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

SciTech Connect

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.

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

1997-02-01

438

Framework for Understanding Lenr Processes, Using Conventional Condensed Matter Physics  

Microsoft Academic Search

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

Scott R. Chubb

2006-01-01

439

Selective Brain Cooling Reduces Water Turnover in Dehydrated Sheep  

PubMed Central

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

Strauss, W. Maartin; Hetem, Robyn S.; Mitchell, Duncan; Maloney, Shane K.; Meyer, Leith C. R.; Fuller, Andrea

2015-01-01

440

Early Transcriptional Response of Soybean Contrasting Accessions to Root Dehydration  

PubMed Central

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

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

441

Selective brain cooling reduces water turnover in dehydrated sheep.  

PubMed

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

Strauss, W Maartin; Hetem, Robyn S; Mitchell, Duncan; Maloney, Shane K; Meyer, Leith C R; Fuller, Andrea

2015-01-01

442

Structure And Mutagenic Conversion of E(1) Dehydrase: at the Crossroads of Dehydration, Amino Transfer, And Epimerization  

SciTech Connect

Pyridoxal 5'-phosphate (PLP) and pyridoxamine 5'-phosphate (PMP) are highly versatile coenzymes whose importance is well recognized. The capability of PLP/PMP-dependent enzymes to catalyze a diverse array of chemical reactions is attributed to fine-tuning of the cofactor-substrate interactions in the active site. CDP-6-deoxy-l-threo-d-glycero-4-hexulose 3-dehydrase (E1), along with its reductase (E{sub 3}), catalyzes the C-3 deoxygenation of CDP-4-keto-6-deoxy-d-glucose to form the dehydrated product, CDP-4-keto-3,6-dideoxy-d-glucose, in the ascarylose biosynthetic pathway. This product is the progenitor to most 3,6-dideoxyhexoses, which are the major antigenic determinants of many Gram-negative pathogens. The dimeric [2Fe-2S] protein, E{sub 1}, cloned from Yersinia pseudotuberculosis, is the only known enzyme whose catalysis involves the direct participation of PMP in one-electron redox chemistry. E{sub 1} also contains an unusual [2Fe-2S] cluster with a previously unknown binding motif (C-X{sub 57}-C-X{sub 1}-C-X{sub 7}-C). Herein we report the first X-ray crystal structure of E{sub 1}, which exhibits an aspartate aminotransferase (AAT) fold. A comparison of the E{sub 1} active site architecture with homologous structures uncovers residues critical for the dehydration versus transamination activity. Site-directed mutagenesis of four E{sub 1} residues, D194H, Y217H, H220K, and F345H, converted E{sub 1} from a PMP-dependent dehydrase to a PLP/glutamate-dependent aminotransferase. The E{sub 1} quadruple mutant, having been conferred this altered enzyme activity, can transaminate the natural substrate to CDP-4,6-dideoxy-4-amino-d-galactose without E{sub 3}. Taken together, these results provide the molecular basis of the functional switch of E{sub 1} toward dehydration, epimerization, and transamination. The insights gained from these studies can be used for the development of inhibitors of disease-relevant PLP/PMP-dependent enzymes.

Smith, P.; Szu, P.-H.; Bui, C.; Liu, H.-w.; Tsai, S.-C.

2009-05-26

443

Potentially Prebiotic Syntheses of Condensed Phosphates  

NASA Technical Reports Server (NTRS)

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.

Keefe, Anthony D.; Miller, Stanley L.

1996-01-01

444

Integrated rig for the production of boron nitride nanotubes via the pressurized vapor-condenser method  

DOEpatents

An integrated production apparatus for production of boron nitride nanotubes via the pressure vapor-condenser method. The apparatus comprises: a pressurized reaction chamber containing a continuously fed boron containing target having a boron target tip, a source of pressurized nitrogen and a moving belt condenser apparatus; a hutch chamber proximate the pressurized reaction chamber containing a target feed system and a laser beam and optics.

Smith, Michael W; Jordan, Kevin C

2014-03-25

445

Integrated Rig for the Production of Boron Nitride Nanotubes via the Pressurized Vapor-Condenser Method  

NASA Technical Reports Server (NTRS)

An integrated production apparatus for production of boron nitride nanotubes via the pressure vapor-condenser method. The apparatus comprises: a pressurized reaction chamber containing a con