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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

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

3

Dehydration  

MedlinePLUS

... change - Use this tool to play your goals. Hot Topics Ebola: The Facts How to Make Sense ... from lots of physical activity, especially on a hot day. Even mild dehydration can affect an athlete's ...

4

Dehydration  

MedlinePLUS

... and dehydration. In: Marx JA, Hockberger RS, Walls RM, et al, eds. Rosen's Emergency Medicine: Concepts and ... chap 171. Greenbaum LA. Deficit therapy. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson ...

5

Effect of Dehydration Reaction on Serpentinite Deformation in Torsion  

NASA Astrophysics Data System (ADS)

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

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

2003-12-01

6

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

7

(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

8

Thermodynamic forward modeling of progressive dehydration reactions during subduction of oceanic crust under greenschist facies conditions  

NASA Astrophysics Data System (ADS)

We developed a new approach to the study of dehydration reactions using thermodynamic forward modeling based on the differential thermodynamic approach (the Gibbs' method) and the use of mass balance equations. We applied the modeling to mafic systems under conditions of the greenschist facies in order to investigate continuous, progressive dehydration reactions during subduction of oceanic crust. By specifying the changes in P- T, the model enables us to predict changes in modal mineralogy and composition as well as the incremental amount of water produced. Calculations for rocks of MORB (mid-ocean ridge basalt) bulk composition subducting along several typical P- T paths show that dehydration proceeds rapidly near the boundary between the greenschist and (epidote-) amphibolite facies, where chlorite is reacted out. The calculated depths for peak rates of dehydration correlate well with peaks in clusters of seismic activity and the depth ranges of low-frequency tremors and high-Poisson's ratio in the subduction zones of SW Japan and Cape Mendocino. This finding indicates a strong causal linkage between seismic phenomena and dehydration reactions in subducting oceanic crust.

Kuwatani, Tatsu; Okamoto, Atsushi; Toriumi, Mitsuhiro

2011-07-01

9

Heat-transfer characteristics in tert-butanol dehydration reaction used for heat transport  

SciTech Connect

The reaction system of tert-butanol/isobutene/water was considered for use in chemical heat transport. In this study, the heat-transfer characteristics in an endothermic tert-butanol dehydration reaction which occurred in the heat-supply side of this reaction system was investigated. The heat flow was obtained by measuring the reactant composition change and temperature change in the catalyst bed. The heat flow consists of reaction heat, the latent heat of isobutene, and sensible heat in this reaction system. Numerical calculations based on a two-dimensional model were carried out and the results showed good agreement with experiment. It was noticed that the heat flow with chemical reaction was much higher than without reaction. These results indicated that the dehydration reaction promoted the heat-transfer rate, because of the increase in temperature difference between the heating medium and the wall by making use of chemical reaction for a heat transport. The apparent local heat-transfer coefficient with chemical reaction was higher than without reaction. The possibility of a high efficiency heat transport which used this reaction system was suggested.

Kiguchi, Yuji; Watanabe, Takayuki; Kanzawa, Atsushi [Tokyo Inst. of Tech. (Japan). Dept. of Chemical Engineering

1996-07-01

10

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

11

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

NASA Astrophysics Data System (ADS)

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

Popp, T.; Kern, H.

1993-11-01

12

Dehydration reactions and intermediate depth earthquakes: Is gypsum the right analog material for an experimental investigation?  

NASA Astrophysics Data System (ADS)

In addition to melting or runaway creep along shear zones, plastic instabilities and solid-solid phase transitions, the mechanical effect of dehydration reactions has been suggested as a process responsible for the occurrence of intermediate depth earthquakes: If the porosity and permeability of the source region are low and the overall molar volume change of the reaction is positive the effective pressure acting on the rock is significantly reduced. Rocks initially deforming in their ductile field could then embrittle and fail. Experimental investigations have previously been performed on both dehydrating gypsum as an analog material and natural rock samples like serpentinite (antigorite). Dehydration in nature occurs syntectonically and the occurrence of earthquakes always requires at least a partial release of stored elastic energy associated with a drop in stress. Therefore only those deformation experiments are significant that are performed in parallel with the progressing reaction. In addition, at constant strain rate, the measured stress-strain curve must show a significant and rapid stress drop which is symptomatic for brittle failure. If this feature is not observed for a specific analog material, it is not suitable for the investigation of the above process in the context of earthquakes. For this reaction induced embrittlement to be expected the hydrous material should show brittle failure at low confining pressures. Nominally dry cylindrical samples of finegrained natural gypsum were strained up to 15% in a gas-medium apparatus at 0.1 to 50 MPa confining pressure, 20 to 110^oC and a strain rate of 1.5 \\cdot 10-6 to 1.5 \\cdot 10-5 1/s. The samples showed nearly ideally ductile behavior suggesting cataclastic flow. The flow stress was independent of strain rate, decreased with decreasing confining pressure and increasing temperature and had a maximum of 80 MPa. Only at room temperature and ambient pressure did the samples show slow strain weakening indicating ductile stress relaxation. The maximum flow stress in this case was only 30 MPa. This raises the question if for the case of gypsum a reaction induced reduction in effective pressure can initiate embrittlement. Results on clarifying deformation experiments under reaction conditions will be presented in addition to the results summarized above.

Milsch, H.; Scholz, C.

2003-04-01

13

High-Resolution, Non-Lithographic Transfer of Patterned Metal Films via an Interfacial Dehydration Reaction  

NASA Astrophysics Data System (ADS)

When silicon or metal oxide surfaces bearing hydroxyl groups (-OH) are brought into contact, a dehydration reaction can occur at the interface. This interfacial reaction produces stable oxygen bridges, resulting in a permanent seal between the two surfaces. We have exploited this interfacial chemistry to induce transfer of patterned metal from one surface to another. In particular, gold/titanium (Au/Ti) patterns were transferred from stamps with relief features onto thin flat pieces of elastomeric polydimethylsiloxane (PDMS), where the Ti bonds to the PDMS. Arrays of sharply-defined metal lines, 500 nm wide spaced 1 micron apart, were successfully transferred from a SiO2 stamp onto PDMS. Additionally, we have also fabricated electrical contacts for thin film organic transistors using this process. This additive pattern transfer technique does not require further etch-back, making it an attractive alternative to conventional lithographic and microcontact printing techniques.

Loo, Yueh-Lin; Rogers, John A.

2002-03-01

14

Theoretical study of dehydration-carbonation reaction on brucite surface based on ab initio quantum mechanic calculations  

NASA Astrophysics Data System (ADS)

The carbonation of brucite (Mg(OH)2) has been considered as a potential technology for cleaning industrial carbon dioxide waste. The kinetics of the reaction Mg(OH)2 + CO2 -> MgCO3 + H2O have been studied experimentally at 573°C by Bearat at al. [1]. Their experiments suggest that the carbonation of magnesium hydroxide proceeds by the reaction Mg(OH)2 -> MgO + H2O followed by the adsorption of CO2 molecules on the dehydrated brucite surface. Due to the large difference in volumes between Mg(OH)2 and MgO, dehydration causes the formation of dislocations and cracks, allowing water molecules to leave the brucite surface and facilitating the advance of the carbonation front in the bulk solid. The detailed mechanism of this process is however unknown. We used the Car-Parrinello ab initio molecular dynamics method to study the structure and dynamics of the (0001), (1-100) and (11-20) surfaces of brucit and calculated the enthalpy and activation barrier of H2O nucleation and dehydration on different surfaces. The results obtained are in agreement with previous studies of brucite dehydration by Masini and Bernasconi [2]. The reactive Car-Parrinello molecular dynamics method [3] has been applied to investigate the detailed mechanism of the dehydration-carbonation reaction at the (1-100) interface of brucite with the gas phase. Based on the results of our MD simulations and the calculated enthalpy of CO2 adsorption on the dehydrated brucite surfaces we propose a mechanism for the dehydration/carbonation reaction. [1] Bearat H, McKelvy MJ, Chizmeshya AVG, Sharma R, Carpenter RW (2002) J. Amer. Ceram. Soc. 85(4):742 [2] Masini P and Bernasconi M (2001) J. Phys. Cond. Mat. 13: 1-12 [3] Iannuzzi M, Laio A and Parrinello M (2003) Phys. Rev. Lett. (submitted)

Churakov, S. V.; Parrinello, M.

2003-04-01

15

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

16

POLLUTION PREVENTION IN INDUSTRIAL CONDENSATION REACTIONS  

EPA Science Inventory

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

17

Einstein Condensation Mechanism for Low Energy Nuclear Reactions and Transmutation Processes in Condensed Matter  

E-print Network

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 6 result indicates that (d ? Li) reactions may dominate over (d+d) reactions in LENR experiments. 1.

Yeong E. Kim; Er L. Zubarev

18

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

19

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

20

In situ spectroscopic observations of pressure-induced condensation of trimethylsilanol and behavior of dehydrated molecular water  

NASA Astrophysics Data System (ADS)

This report is the first describing a letter of pressure-induced condensation of silanol. Raman and infrared absorption spectra of trimethylsilanol were observed at room temperature and at pressures up to 3.3 GPa. After solidification at 0.3 GPa, the OH vibration mode shifted to lower frequencies along with increasing pressure with a notably large pressure coefficient (-107 cm-1/GPa), thereby indicating that hydrogen bonding in trimethylsilanol had strengthened prominently. Along with increased hydrogen-bond interaction, condensation of trimethylsilanol forming hexamethyldisiloxane and molecular water were observed. The marked shift in the OH stretching mode in the released H2O suggests considerable intermolecular interaction with hexamethyldisiloxane.

Shinozaki, Ayako; Noguchi, Naoki; Kagi, Hiroyuki

2013-06-01

21

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

22

Synthesis of a stable selenoaldehyde by self-catalyzed thermal dehydration of a primary-alkyl-substituted selenenic Acid.  

PubMed

The unprecedented dehydration of a selenenic acid (RCH2 SeOH) to a selenoaldehyde (RCH?Se) has been demonstrated. A primary-alkyl-substituted selenenic acid was synthesized for the first time by taking advantage of a bulky cavity-shaped substituent. Upon heating in solution, the selenenic acid underwent thermal dehydration to produce a stable selenoaldehyde, which was isolated as stable crystals and crystallographically characterized. Investigation of the reaction mechanism revealed that this ??dehydration reaction involves two processes, both of which reflect the characteristics of a selenenic acid: 1)?dehydrative condensation of two molecules of selenenic acid to generate a selenoseleninate intermediate [RCH2 SeSe(O)CH2 R], an isomer of a selenenic anhydride, and 2)?subsequent ??elimination of the selenenic acid from this intermediate to form a C?Se double bond, which establishes the self-catalyzed ??dehydration of the selenenic acid. PMID:25411119

Sase, Shohei; Kakimoto, Ryo; Goto, Kei

2015-01-12

23

Dehydration affects the electronic structure of the primary electron donor in bacterial photosynthetic reaction centers: evidence from visible-NIR and light-induced difference FTIR spectroscopy.  

PubMed

The photosynthetic reaction center (RC) is a membrane pigment-protein complex that catalyzes the initial charge separation reactions of photosynthesis. Following photoexcitation, the RC undergoes conformational relaxations which stabilize the charge-separated state. Dehydration of the complex inhibits its conformational dynamics, providing a useful tool to gain insights into the relaxational processes. We analyzed the effects of dehydration on the electronic structure of the primary electron donor P, as probed by visible-NIR and light-induced FTIR difference spectroscopy, in RC films equilibrated at different relative humidities r. Previous FTIR and ENDOR spectroscopic studies revealed that P, an excitonically coupled dimer of bacteriochlorophylls, can be switched between two conformations, P866 and P850, which differ in the extent of delocalization of the unpaired electron between the two bacteriochlorophyll moieties (PL and PM) of the photo-oxidized radical P(+). We found that dehydration (at r = 11%) shifts the optical Qy band of P from 866 to 850-845 nm, a large part of the effect occurring already at r = 76%. Such a dehydration weakens light-induced difference FTIR marker bands, which probe the delocalization of charge distribution within the P(+) dimer (the electronic band of P(+) at 2700 cm(-1), and the associated phase-phonon vibrational modes at around 1300, 1480, and 1550 cm(-1)). From the analysis of the P(+) keto C[double bond, length as m-dash]O bands at 1703 and 1713-15 cm(-1), we inferred that dehydration induces a stronger localization of the unpaired electron on PL(+). The observed charge redistribution is discussed in relation to the dielectric relaxation of the photoexcited RC on a long (10(2) s) time scale. PMID:25188921

Malferrari, Marco; Turina, Paola; Francia, Francesco; Mezzetti, Alberto; Leibl, Winfried; Venturoli, Giovanni

2015-02-01

24

A combined experimental and computational study of the catalytic dehydration of glycerol on microporous zeolites: an investigation of the reaction mechanism and acrolein selectivity.  

PubMed

The catalytic activity and the acrolein selectivity for liquid phase glycerol dehydration on ? zeolites (HNa-?-k) were found to be dependent on the reaction temperature as well as on the amount of acid sites on the zeolites. An increase in the reaction temperature favors the acrolein selectivity. The acrolein selectivity increases with the Na(+)/H(+) ratio and the glycerol conversion decreases with it so that a maximum acrolein yield is obtained when a certain amount of acidic sites are replaced by non-active Na(+) sites. The computational results indicate that 3-hydoxylpropanal (HPA) is an important intermediate that determines the final product selectivity. The relative rates of the different reaction pathways for HAP can be affected by the amount of water molecules involved in its homogeneous reaction. Based on the reaction mechanism proposed, it was hypothesized that smaller pores reduce activity but increase selectivity to acrolein, and results of the H-MFI zeolite were consistent with this hypothesis. Our work provides important insight into the overall landscape of the reaction mechanism and can be used to help design reaction systems that have good acrolein selectivity for the liquid phase glycerol dehydration reactions. PMID:24158544

Lin, Xufeng; Lv, Yanhong; Qu, Yuanyuan; Zhang, Guodong; Xi, Yanyan; Phillips, David L; Liu, Chenguang

2013-12-14

25

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.

26

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

Microsoft Academic Search

Summary Published data on adsorption and condensation of amino acids, purine and pyrimidine bases, sugars, nucleosides, and nucleotides are analyzed in connection with Bernal's hypothesis that clays and other minerals may have provided the most likely surface for adsorption and condensation of these molecules in prebiotic times. Using surface concentration and reaction rate as the main criteria for the feasibility

N. Lahav; S. Chang

1976-01-01

27

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.

Kessler, James H.; Galvan, Patricia M.

2007-01-01

28

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

29

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

NASA Astrophysics Data System (ADS)

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

2014-06-01

30

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

31

First observation of a mass independent isotopic fractionation in a condensation reaction  

NASA Technical Reports Server (NTRS)

Thiemens and Heidenreich (1983) first demonstrated that a chemically produced mass independent isotopic fractionation process could produce an isotopic composition which is identical to that observed in Allende inclusions. This raised the possibility that the meteoritic components could be produced by chemical, rather than nuclear processes. In order to develop a mechanistic model of the early solar system, it is important that relevant reactions be studied, particularly, those which may occur in the earliest condensation reactions. The isotopic results for isotopic fractionations associated with condensation processes are reported. A large mass independent isotopic fractionation is observed in one of the experiments.

Thiemens, M. H.; Nelson, R.; Dong, Q. W.; Nuth, Joseph A., III

1994-01-01

32

Zeolite an efficient catalyst for the Biginelli condensation reaction  

Microsoft Academic Search

A zeolite catalyzed, single step and environmentally friendly process for synthesis of classical Biginelli reaction was investigated.\\u000a For this reaction Transition metal\\/Y zeolites were prepared by microwave solid-state and aqueous solution ion-exchange methods.\\u000a The yield of reactions was increased in order of CuY > CoY > NiY > MnY ? FeY > VY > CrY > ZnY for the solid-state zeolite\\u000a ion-exchange and CuY > CoY > NiY > MnY > CrY > VY > ZnY > FeY for the aqueous solution ion-exchange. The solid-state ion-exchange\\u000a zeolite by

Mojgan Zendehdel; A. Mobinikhaledi; A. Asgari

2008-01-01

33

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

SciTech Connect

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

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

1993-12-31

34

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

35

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

SciTech Connect

Changes in coal structure that occur during coal drying and steam pretreatments will be measured in order to determine what effect water has on retrograde/condensation reactions, and to determine how water enhances coal reactivity toward liquefaction. Coal drying experiments were begun using thermal, microwave, and chemical methods; NMR data were collected. A stirred microautoclave reactor system was acquired.

Miknis, F.P.

1992-10-01

36

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

37

Rapid and efficient functionalized ionic liquid-catalyzed aldol condensation reactions associated with microwave irradiation.  

PubMed

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

38

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

39

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

40

Equation of state and reaction rate for condensed-phase explosives  

Microsoft Academic Search

The wide-ranging equation of state is a nonideal equation of state based on empirical fitting forms argued from thermodynamic considerations that yield the proper physical features of detonation. The complete equation of state forms are presented and the equation of state and a reaction rate are calibrated for the condensed-phase explosive PBX-9502. Experimental overdriven Hugoniot data are used to calibrate

B. L. Wescott; D. Scott Stewart; W. C. Davis

2005-01-01

41

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

42

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

PubMed

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

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

2013-09-01

43

Amine functionalized K10 montmorillonite: a solid acid-base catalyst for the Knoevenagel condensation reaction.  

PubMed

Different amine functionalized K10 montmorillonites were hydrothermally fabricated by a simple method of treatment of the neat clay with different amine solutions and used as heterogeneous catalysts towards the Knoevenagel condensation reaction. Catalytic results show that the di-amine functionalized K10 montmorillonite exhibits high efficacy for promoting this reaction at room temperature and in the absence of a solvent. The solid catalyst was characterized using a variety of different techniques; including Fourier transform infrared spectroscopy (FT-IR), nitrogen physisorption measurements, (29)Si CP MAS NMR spectroscopy, NH3-temperature programmed desorption (NH3-TPD), X-ray powder diffraction (XRD), and field emission scanning electron microscopy (FESEM). The catalyst could be recycled and reused for several runs without any loss of inherent catalytic activity. PMID:23400041

Varadwaj, G Bishwa Bidita; Rana, Surjyakanta; Parida, K M

2013-04-14

44

Alternative interpretations of low-energy nuclear reaction processes with deuterated metals based on the Bose-Einstein condensation mechanism  

E-print Network

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. 1.

Yeong E. Kim; Thomas O. Passell

45

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

SciTech Connect

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

COWLEY, W.L.

1999-06-24

46

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

47

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

48

Green condensation reaction of aromatic aldehydes with active methylene compounds catalyzed by anion-exchange resin under ultrasound irradiation.  

PubMed

To realize a practical and green chemistry, two important challenges need to be addressed, namely the effective process for the activation of reaction and efficient, eco-friendly and robust chemical methods for the reaction conversion to target products via highly selective catalytic and reactions. Ultrasonic energy promotes the conversion process through its special cavitational effects. Combined with anion-exchange resin as a heterogeneous, reusable and efficient catalyst, Ultrasonic energy enhances the Knoevenagel condensation and leads to reduced reaction time at lower reaction temperature with less amounts of solvent and catalyst. PMID:25112685

Ammar, Hafedh Belhadj; Chtourou, Manef; Frikha, Mohamed Hédi; Trabelsi, Mahmoud

2015-01-01

49

Ab initio calculations concerning the reaction mechanism of the copper(II) catalyzed glycine condensation in aqueous sodium chloride solution  

NASA Astrophysics Data System (ADS)

Starting from results of detailed experimental work concerning the copper(II) catalyzed glycine condensation, quantum-mechanical studies of species which should be relevant for the reaction mechanism are presented. This reaction is of special interest because it could be important in explaining the formation of the first peptides on prebiotic earth. SCF geometry optimizations of aquo-chloro-glycinato—copper(II) complexes at Hartree—Fock level were performed especially to study the necessity of chlorine for the reaction. In that way a hypothetical reaction mechanism could be confirmed. Structural distortions as expected from the Jahn—Teller effect resulted from optimizations of copper complexes in C1 geometry.

Liedl, Klaus R.; Rode, Bernd M.

1992-09-01

50

THE DEHYDRATION OF TOBERMORITE  

Microsoft Academic Search

Tobermorite (Ca 4 (Si6018H2)Ca.4I-IaO ) is a hydrated calcimn silicate mineral with a layer structure which in some respects resembles that of vermiculite. Its dehydration has been studied using single crystals from Ballyeraigy, N. Ireland. The three most frequently encountered hych'ation states are characterized by basal spacings (d002) of 14.0, 11.3 and 9.35~. Dehydration to the 9.35~ state is complete

F. W. TAYLOR

51

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

52

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

53

Reactions in condensed formic acid (HCOOH) induced by low energy (< 20 eV) electrons.  

PubMed

The interaction of low energy (< 20 eV) electrons with a five monolayer (ML) film of formic acid (HCOOH) deposited on a cryogenically cooled monocrystalline Au substrate is studied by electron stimulated desorption (ESD) of negatively charged fragment ions. A comparison with results from gas phase experiments demonstrates the strong effect of the environment for negative ion formation via dissociative electron attachment (DEA). From condensed phase formic acid (FA) a strong H desorption signal from a resonant feature peaking at 9 eV is observed. In the gas phase, the dominant reaction is neutral hydrogen abstraction generating HCOO- within a low energy resonance, peaking at 1.25 eV. ESD studies on the isotopomers HCOOD and DCOOH indicate effective H/D exchange in the precursor ion at 9 eV prior to dissociation. The evolution of the desorption signals in the course of electron irradiation and the features in the thermal desorption spectra (TDS) of the electron irradiated film suggest the formation of CO2 at electron energies above 8 eV. PMID:19791345

Sedlacko, Tibor; Balog, Richard; Lafosse, Anne; Stano, Michal; Matejcik, Stefan; Azria, Roger; Illenberger, Eugen

2005-03-21

54

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

SciTech Connect

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

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

1996-08-01

55

Polarizabilities in the condensed phase and the local fields problem: A direct reaction field formulation  

NASA Astrophysics Data System (ADS)

A consistent derivation is given for local field factors to be used for correcting measured or calculated static (hyper)polarizabilities in the condensed phases. We show how local fields should be used in the coupled perturbative Hartree-Fock or finite field methods for calculating these properties, specifically for the direct reaction field (DRF) approach, in which a quantum chemically treated "solute" is embedded in a classical "solvent" mainly containing discrete molecules. The derivation of the local fields is based on a strictly linear response of the classical parts and they are independent of any quantum mechanical method to be used. In applications to two water dimers in two basis sets it is shown that DRF matches fully quantum mechanical results quite well. For acetone in eleven different solvents we find that if the solvent is modeled by only a dielectric continuum (hyper)polarizabilities increase with respect to their vacuum values, while with the discrete model they decrease. We show that the use of the Lorentz field factor for extracting (hyper)polarizabilities from experimental susceptibilities may lead to serious errors.

van Duijnen, Piet Th.; de Vries, Alex H.; Swart, Marcel; Grozema, Ferdinand

2002-11-01

56

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

57

Experimental Test of Bose-Einstein Condensation Mechanism for Low Energy Nuclear Reaction in Nanoscale Atomic Clusters  

Microsoft Academic Search

We report preliminary results of experimental test of the Bose-Einstein condensation (BEC) mechanism for ultra low energy nuclear fusion in nano-scale atomic clusters at pressures up to a 20,000 psi and at both room temperature and liquid nitrogen temperatures. BEC of integer-spin nuclei was suggested as a possible mechanism for ultra low-energy nuclear reaction in 1998. Recently, theoretical studies of

Yeong E. Kim; David S. Koltick; Ryan Prenger; Jeff Myers; Rhoda Koltick

2005-01-01

58

Synthesis of 1,5-Benzodiazepine and Its Derivatives by Condensation Reaction Using H-MCM-22 as Catalyst  

PubMed Central

A simple and versatile method for the synthesis of 1,5-benzodiazepines is via condensation of o-phenylenediamines (OPDA) and ketones in the presence of catalytic amount of H-MCM-22 using acetonitrile as solvent at room temperature. In all the cases, the reactions are highly selective and are completed within 1–3?h. The method is applicable to both cyclic and acyclic ketones without significant differences. The reaction proceeds efficiently under ambient conditions with good-to-excellent yields. PMID:22570531

Majid, Sheikh Abdul; Khanday, Waheed Ahmad; Tomar, Radha

2012-01-01

59

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

SciTech Connect

The authors have observed clear signatures for neutron emission during deuteron infusion into metals, implying the occurrence of nuclear fusion in condensed matter near room temperature. The low-level nuclear phenomenon has been demonstrated in collaborative experiments at Brigham Young Univ., at the Gran Sasso Laboratory in Italy, and at the Los Alamos National Lab. The authors have shown that neutron emission can be induced in metals using both electrochemical and variational temperature pressure means to generate non-equilibrium conditions. Observed average neutron emission rates are approximately 0.04-0.4 n[degrees]/s. Current efforts focus on trying to understand and control the phenomenon. In particular, there is a desire to understand the correlation of neutron yields with parameters such as hydrogen/metal ion ratio, pressure (induced, for example, by electrical field or gas pressure or mechanical pressure), temperature variation, hydride phase changes, and surface conditions, e.g., a palladium coating on titanium. Experimentalists want to know if fusion arises due to the close proximity of these deuterons in the lattice (piezonuclear fusion), or possibly from [open quotes]microscopic hot fusion[close quotes] accompanying strong electric fields at propagating cracks in the hydride. The latter interpretation would imply neutron emission in bursts. The experiments show clear evidence for emission of [approximately]10[sup 2] neutrons in bursts lasting < 128 [mu]s, although random neutron-singles emissions were also observed. Experiments now underway to compare the d-d, and d-t reaction rates will be important to a consistent description of the new phenomenon. Careful scrutiny of this effect could increase our understanding of heat, helium-3, and tritium production in the earth, other planets, and even the stars.

Jones, S.E.; Palmer, E.P.; Czirr, J.B.; Decker, D.L.; Jensen, G.L.; Thorne, J.M.; Taylor, S.F. (Brigham Young Univ., Provo, UT (United States)); Rafelski, J. (Univ. of Arizona, Tucson, AZ (United States))

1990-01-01

60

Assessment of the importance of the solvent in the calculation of condensed Fukui function: a self-consistent reaction field calculation study  

Microsoft Academic Search

The condensed Fukui function is used as a descriptor in quantitative structure–activity relationships. It is a well-known fact that the rate of a reaction is influenced by the presence of the solvent system associated with the molecules. In this investigation, the importance of a solvent in the calculation of the condensed Fukui function has been assessed with the help of

D. Sivanesan; R. Amutha; V. Subramanian; B. U. Nair; T. Ramasami

1999-01-01

61

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

62

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

63

Integrated approach to study the dehydration kinetics of nitrofurantoin monohydrate.  

PubMed

There is a need for thorough knowledge of solid-state transformations in order to implement quality by design (QbD) methodology in drug development. The present study was aimed at gaining a mechanistic understanding of the dehydration of nitrofurantoin monohydrate II (NF-MH). The dehydration was studied using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), hot-stage microscopy (HSM), and variable temperature X-ray powder diffraction (VT-XRPD). Isothermal TGA data were used to study dehydration kinetics using model-fitting and model-free approaches. Model-fitting analysis indicated a good fit for several models derived from nucleation-growth and/or geometric contraction mechanisms. However, based on visual observations during HSM, Avrami-Erofeyev equations A3 and A4, indicating nucleation-growth phenomenon, were found to be the most suitable kinetic models. HSM showed initiation of dehydration with random nucleation, and nuclei coalesced with the progress of dehydration reaction. VT-XRPD revealed formation of anhydrate beta form on dehydration of NF-MH. The phenomenon of random nucleation is justified based on the crystal structure of NF-MH, which showed presence of water molecules in an isolated manner, prohibiting directional dehydration. It was found that supplementary information from HSM and VT-XRPD can be valuable to gain a better understanding of dehydration from formal solid-state kinetics analysis. PMID:20575054

Koradia, Vishal; de Diego, Heidi Lopez; Elema, Michiel Ringkjøbing; Rantanen, Jukka

2010-09-01

64

Low-energy electron-induced chemistry of condensed-phase hexamethyldisiloxane: Initiating dissociative process and subsequent reactions  

NASA Astrophysics Data System (ADS)

Thin films of condensed hexamethyldisiloxane (HMDSO) have been exposed to electron irradiation at incident energies between 5 and 15 eV and analysed afterwards by thermal desorption spectrometry (TDS). Formation of products is observed at energies at and above 11 eV and quantified at 15 eV by comparison with reference samples of known composition. Gas-phase measurements aiming at detection of dissociative electron attachment (DEA) were, in addition, performed to obtain more insight into the dominant electron-induced dissociation channel expected to initiate further reactions in the condensed phase. Apart from CH4 which is the most obvious product present in exposed films of HMDSO, tetramethylsilane (TMS) and smaller amounts of C2H6 have been detected. The quantity of the products is by one to two orders of magnitude smaller than the amount of decomposed HMDSO. In addition, signals ascribed to unquantified amounts of larger siloxanes have been observed. The present results together with previous gas-phase results from literature suggest that dissociative ionisation leading to Si-C bond rupture and release of a methyl radical is the most important electron-driven initial reaction step. Possible mechanisms of the subsequent reactions induced by the fragments of the initial dissociation reaction are reviewed and discussed in relation to the observed product quantities.

Ipolyi, I.; Burean, E.; Hamann, T.; Cingel, M.; Matejcik, S.; Swiderek, P.

2009-05-01

65

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

66

Mechanism of the Intramolecular Claisen Condensation Reaction Catalyzed by MenB, a Crotonase Superfamily Member†  

PubMed Central

MenB, the 1,4-dihydroxy-2-naphthoyl-CoA synthase from the bacterial menaquinone biosynthesis pathway, catalyzes an intramolecular Claisen condensation (Dieckmann reaction) in which the electrophile is an unactivated carboxylic acid. Mechanistic studies on this crotonase family member have been hindered by partial active site disorder in existing MenB X-ray structures. In the current work the 2.0 Å structure of O-succinylbenzoyl-aminoCoA (OSB-NCoA) bound to the MenB from Escherichia coli provides important insight into the catalytic mechanism by revealing the position of all active site residues. This has been accomplished by the use of a stable analogue of the O-succinylbenzoyl-CoA (OSB-CoA) substrate in which the CoA thiol has been replaced by an amine. The resulting OSB-NCoA is stable and the X-ray structure of this molecule bound to MenB reveals the structure of the enzyme-substrate complex poised for carbon-carbon bond formation. The structural data support a mechanism in which two conserved active site Tyr residues, Y97 and Y258, participate directly in the intramolecular transfer of the substrate ?-proton to the benzylic carboxylate of the substrate, leading to protonation of the electrophile and formation of the required carbanion. Y97 and Y258 are also ideally positioned to function as the second oxyanion hole required for stabilization of the tetrahedral intermediate formed during carbon-carbon bond formation. In contrast, D163, which is structurally homologous to the acid-base catalyst E144 in crotonase, is not directly involved in carbanion formation and may instead play a structural role by stabilizing the loop that carries Y97. When similar studies were performed on the MenB from Mycobacterium tuberculosis, a twisted hexamer was unexpectedly observed, demonstrating the flexibility of the interfacial loops that are involved in the generation of the novel tertiary and quaternary structures found in the crotonase superfamily. This work reinforces the utility of using a stable substrate analogue as a mechanistic probe in which only one atom has been altered leading to a decrease in ?-proton acidity. PMID:21830810

Li, Huei-Jiun; Li, Xiaokai; Liu, Nina; Zhang, Huaning; Truglio, James J.; Mishra, Shambhavi; Kisker, Caroline; Garcia-Diaz, Miguel; Tonge, Peter J.

2014-01-01

67

Kinetics and Mechanism of Dehydration of Lawsonite and Blueschist  

NASA Astrophysics Data System (ADS)

The dehydration of hydrous minerals is the source of aqueous fluids at intermediate-depth in subduction zones. The fluid released by the dehydration of hydrous minerals may consist in a free fluid phase if dehydration reactions are much faster than the hydration of the surrounding mantle. In the latter situation, the release of a free fluid phase may trigger intermediate-depth seismicity. For instance, the location of the ';upper-plane seismic belt' within the subducting oceanic crust has been observed at conditions that fit the dehydration of lawsonite. The understanding of the consequences of lawsonite and blueschist dehydration requires that their kinetics and mechanism are well characterized. We have therefore measured the kinetics of dehydration of lawsonite as well as a lawsonite-rich blueschist in situ at high pressure and high temperature by time resolved synchrotron X-ray diffraction in a closed system, in a Paris-Edinburgh cell. Lawsonite was from single crystals of the Longvale Quarry (Laytonville, Mendocino, CA). The blue schist matrix was artificially enriched in lawsonite, which would have been below detection limits otherwise. Measurements were performed between 2 and 5 GPa and dehydration was observed between 600 and 700°C, i.e. at temperatures slightly lower than those currently reported for the stability of lawsonite. From the analysis of diffraction patterns and reaction progress data, we determined that the release of aqueous fluid occurs very rapidly, at minimum rates of 10-5 m3fluid.m3rock.s-1. This exceeds by orders of magnitude the typical time scale sofar envisioned for such metamorphic reactions. Due to the release of a free fluid phase, the reaction products and zoïsite in particular display a grain size much larger than the initial one. Such a increase in grain size during the dehydration of lawsonite also has consequences on seismicity, which will be discussed.

Daniel, I.; Perrillat, J.; Reynard, B.

2013-12-01

68

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

Microsoft Academic Search

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

J. Kasagi; H. Yonemura

2009-01-01

69

Adsorption and reaction of acrolein on titanium oxide single crystal surfaces: coupling versus condensation  

Microsoft Academic Search

The reactions of acrolein have been investigated on TiO2(001) single crystal surfaces by temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS). Two carbon–carbon bond-forming reactions were observed. The first, on defect-containing surfaces, is reductive coupling to form olefins. The high reaction yield of ca. 80% shows the high activity of such surfaces

A. B. Sherrill; H. Idriss; M. A. Barteau; J. G. Chen

2003-01-01

70

Condensed phase combustion travelling waves with sequential exothermic or endothermic reactions  

Microsoft Academic Search

The one-dimensional propagation of a combustion wave through a premixed solid fuel for two-stage kinetics is studied. We re-examine the analysis of a single reaction travelling-wave and extend it to the case of two-stage reactions. We derive an expression for the travelling wave speed in the limit of large activation energy for both reactions. The analysis shows that when both

F Liu; D L S McElwain

2003-01-01

71

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

72

Food dehydration and product structure  

Microsoft Academic Search

Dehydration of biological material is a controlled effort to preserve the structure or create a new one that serves for functional purposes. In this context, food dehydration is revisited from the perspective of recent advances in food materials science, knowledge from desiccation in Nature, microstructural probing, novel processing technologies and deeper insights into drying mechanisms, among others. The role of

José Miguel Aguilera; Amparo Chiralt; Pedro Fito

2003-01-01

73

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

74

Model-free treatment of the dehydration kinetics of nedocromil sodium trihydrate.  

PubMed

The conventional model-fitting approach to kinetic analysis assumes a fixed mechanism throughout the reaction and therefore may be too simplistic for many solid-state reactions. Even for a reaction with a fixed mechanism, model fitting sometimes cannot identify the reaction model uniquely. The alternative model-free approach is sufficiently flexible to allow for a change of mechanism during the course of a reaction and therefore provides a more realistic treatment of solid-state reactions kinetics. The application of model-free analysis to solid-state dehydrations was investigated using the two consecutive dehydration reactions of nedocromil sodium trihydrate. The complexity of such reactions is illustrated by the variation of the activation energy as each dehydration proceeds. The 1st-step dehydration follows one-dimensional phase boundary kinetics until the fraction dehydrated reaches 0.75, and deviates from this model thereafter. The 2nd-step dehydration follows a mechanism intermediate between two- and three-dimensional diffusion that cannot be described by any of the common models. The model-free approach is clearly better than the model-fitting approach for understanding the details of these solid-state dehydration reactions. PMID:12820141

Zhou, Deliang; Schmitt, Eric A; Zhang, Geoff G Z; Law, Devalina; Wight, Charles A; Vyazovkin, Sergey; Grant, David J W

2003-07-01

75

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

76

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

77

Theoretical study of the mechanisms of the hydrolysis and condensation reactions of silicon and titanium alkoxides: similarities and differences.  

PubMed

Stationary states for hydrolysis reactions in M(OCH(3))(4) + nH(2)O (M = Si, Ti; n = 1-3) systems are optimized at the B3LYP and MP2 levels with the Wachters basis set for titanium and the cc-pVDZ set for other atoms. Geometries of these states for M = Ti are characterized by trigonal bipyramidal (water molecules in front-side position) and octahedral coordination (for back-side position). Barrier heights for hydrolysis and condensation are substantially lower than those for silicon in keeping with experimental results. The lowering of the barrier heights on the addition of water molecules in the front-side position (reduction of hydrogen bond strain) exceeds that of the back-side addition (catalytic effect) for both M = Si and Ti, but the difference diminishes with n. The influence of oligomerization of titanium alkoxides on the rate of hydrolysis is studied on the model of the interaction of a Ti(2)(OCH(3))(8) dimer with one and two water molecules. It was shown that only terminal methoxy groups are exposed to hydrolysis and therefore the dimeric structure is retained in the process of the substitution of terminal methoxy groups. Barrier heights for terminal hydrolysis do not differ significantly from those of monomers. Barrier heights for condensation reactions obtained for the 2M(OMe)(n)(OH)(4-n) + H(2)O model system, are substantially (by ca. 10 kcal mol(-1)) lower for M = Ti and in both silicon and titanium species demonstrate a steady growth with n. PMID:20571685

Ignatyev, Igor S; Montejo, Manuel; López González, Juan Jesús

2010-08-14

78

Regioselective aldol condensations of a cholestanone-derived dialdehyde: new twists on a classic reaction  

E-print Network

reaction Scott A. Snyder and E. J. Corey* Department of Chemistry and Chemical Biology, Harvard University in Scheme 1, the test substrate 7 was pre- pared from commercially available 5a-cholestan-3-one (6) via these operations appear routine, it is worth noting that in the initial step the C-2 hydroxyl was installed

Snyder, Scott A.

79

Hydration\\/dehydration characteristics of struvite and dittmarite pertaining to magnesium ammonium phosphate cement systems  

Microsoft Academic Search

Struvite, an important reaction product in magnesium ammonium phosphate cement systems, was synthesized in the laboratory. The elevated-temperature dehydration and then roomtemperature hydration characteristics of the dehydrated products were studied by thermogravimetric analyses and X-ray diffraction techniques. From isothermal experiments, struvite is found to be thermally unstable in air at temperatures above 50 ‡C. Struvite can lose part or all

A. K. Sarkar

1991-01-01

80

An investigation of the role of water on retrograde/condensation reactions and enhanced liquefaction yields. Quarterly progress report, July 1, 1992--September 30, 1992  

SciTech Connect

Changes in coal structure that occur during coal drying and steam pretreatments will be measured in order to determine what effect water has on retrograde/condensation reactions, and to determine how water enhances coal reactivity toward liquefaction. Coal drying experiments were begun using thermal, microwave, and chemical methods; NMR data were collected. A stirred microautoclave reactor system was acquired.

Miknis, F.P.

1992-10-01

81

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

82

Model path-integral dynamics for nonadiabatic reactions in the condensed phase  

NASA Astrophysics Data System (ADS)

We introduce mapping-variable ring polymer molecular dynamics (MV-RPMD), a direct, real-time dynamic technique for the atomistic simulation of nonadiabatic reactions. The dynamics are based on the recently derived exact path-integral Stock-Thoss (PI-ST)representation for the quantum Boltzmann operator that has been previously used to calculate equilibrium properties for N-level systems, and as a way to initialize semiclassical trajectories for the calculation of thermal correlation functions. Both these methods use the Stock-Thoss (ST) mapping protocol to map from a discrete electronic states basis to a continuous Cartesian variables basis, providing the even-handed treatment of electrons and nuclei required to accurately describe their dynamically coupled motions and to describe resonance energy transfer. Like the existing RPMD approach, this method can be used to generate statistically meaningful ensembles of reactive trajectories but, unlike RPMD, it is applicable to photochemical reactions and reactions where proper electronic state quantization is essential. We present the results of simulations using MV-RPMD to calculate correlation functions for a series of model N-level systems over a wide range of nonadiabatic coupling strengths.

Ananth, Nandini; Menzeleev, Artur; Miller, Thomas

2013-03-01

83

Electron-induced reactions in condensed films of acetonitrile and ethane.  

PubMed

Reactions in pure and mixed films of C(2)H(6) and CD(3)CN deposited on a Au surface at 35 K have been induced by low-energy electrons and investigated by Thermal Desorption Spectrometry (TDS). The incident electron energy (E(0)) was varied between 5 and 16 eV and a number of different products were identified. Beside the main products, CD(4), CD(3)H, and C(2)D(6), molecules resulting from atom scrambling during radical chain reactions (C(2)H(5)D) and recombination products (CD(3)CD(2)CN and C(2)H(5)CD(3)) were identified while others were characteristically absent. The quantity of the different products varied with E(0). The observed electron-driven processes are in accord with previous findings from gas phase experiments on dissociative electron attachment and electron impact ionization. On this basis, reaction mechanisms leading to the formation of the observed products are suggested for different ranges of E(0). PMID:17164900

Ipolyi, Imre; Michaelis, Wilfried; Swiderek, Petra

2007-01-01

84

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

85

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

NASA Astrophysics Data System (ADS)

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

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

1992-04-01

86

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

87

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

88

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

SciTech Connect

In this paper, we used mass spectrometry and {sup 29}Si NMR spectroscopy to discover that the length of the alkylene-bridging groups had a pronounced effect on the competition between cyclization and polymerization of {alpha},{omega}-bis(triethoxysilyl)alkanes and on the formation of polymeric gels. While the intramolecular reaction clearly slows gelation, the cyclic disilsesquioxanes are still tetrafunctional monomers theoretically capable of forming polymeric gels. If the ring structures, which bear a striking resemblence to carbohydrates, are preserved through the polymerization, the resulting poly(cyclic disilsesquioxane) gels may have structural similarities to branched or cross-linked carbohydrates, such as cellulose or chitosan. Under base-catalyzed sol-gel polymerization conditions, 3 and 4 (six- and seven-membered cyclic disilsesquioxanes, respectively) quickly reacted to give gels with significant ring opening as determined from the {sup 29}Si chemical shifts in solid-state (CP MAS) NMR spectra. However, gels prepared under acidic conditions reveal some or all of the cyclic disilsesquioxane functionality was preserved in the polymers. 13 refs., 1 fig.

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

1996-09-04

89

Dehydration of glycerol over niobia-supported silicotungstic acid catalysts.  

PubMed

Liquid-phase dehydration of glycerol to acrolein over nanosized niobia-supported silicotungstic acid catalysts was performed to investigate the effect of the silicotungstic acid loading on the catalytic performance of the catalysts. The catalysts were prepared by following an impregnation method with different HSiW loadings in the range of 10-50 wt%. The prepared catalysts were characterized by N2 physisorption, XRD, FT-IR, TPD of ammonia, and TGA. Dehydration of glycerol was conducted in an autoclave reactor under the conditions of controlled reaction temperatures under corresponding pressure. Increasing HSiW loading rapidly increased the acidity of HSiW/Nb205 catalyst and rate of glycerol conversion, but acrolein selectivity decreased due to enhanced deactivation of the catalyst by carbon deposit. Consequently, it was confirmed that catalytic activity for the dehydration of glycerol to acrolein was dependant on the acidity of catalyst and can be controlled by HSiW loading. PMID:23646735

Lee, Young Yi; Ok, Hye Jeong; Moon, Dong Ju; Kim, Jong Ho; Park, Nam Cook; Kim, Young Chul

2013-01-01

90

Dehydration Linked to Greater Stroke Damage  

MedlinePLUS

... page, please enable JavaScript. Dehydration Linked to Greater Stroke Damage Thicker blood may be the reason why, ... Related MedlinePlus Pages Dehydration Fluid and Electrolyte Balance Stroke THURSDAY, Feb. 12, 2015 (HealthDay News) -- People who ...

91

Formation of hydantoins in gasifier condensate water. [5,5-dimethyl hydantoin synthesis by reaction of acetone cyanohydrin with excess ammonium carbonate  

SciTech Connect

A number of 5,5-diakyl and 5-alkylhydantoins have been detected in the condensate water from the gasification of Indian Head (ND) lignite in the University of North Dakota Energy Research Center (UNDERC) slagging fixed bed gasifier. These compounds do not form directly in the gasifier. They were shown to be either absent or present in low concentrations in water samples which were collected from a side stream sampler on the UNDERC gasifier and quickly frozen. When this side stream condensed water was heated in a constant temperature bath at 40/sup 0/C, hydantoin concentrations increased in an approximately second-order manner. The formation is believed to proceed by the Bucherer-Berg reaction, the same reaction used in commercial hydantoin synthesis, from ammonia, carbonate, hydrogen cyanide and various ketones and aldehydes at a pH of 8.5. A kinetic study was undertaken to obtain useful rate data for this reaction. Reliable and reproducible concentration data for acetone and cyanide were impossible to obtain for the raw gasifier condensate water because of the presence of reversible addition products of cyanide such as acetone cyanohydrin and 2-amino-2-methylpropanonitrile as well as large amounts of sulfide. Thus a model system was investigated where acetone cyanohydrin was reacted with excess ammonium carbonate at concentrations approaching those obtained in the condensate water, 0.020M and 0.25M, respectively. The reaction was studied at 50/sup 0/, 70/sup 0/, and 90/sup 0/C using a capillary GC (0V351 phase) for the analysis of 5.5-dimethylhydantoin (DMH) using 4-methoxyphenol as the internal standard. Results are discussed. 8 references, 2 tables.

Olson, E.S.; Worman, J.J.; Diehl, J.W.

1984-12-01

92

Theory of Bose-Einstein condensation mechanism for deuteron-induced nuclear reactions in micro/nano-scale metal grains and particles.  

PubMed

Recently, there have been many reports of experimental results which indicate occurrences of anomalous deuteron-induced nuclear reactions in metals at low energies. A consistent conventional theoretical description is presented for anomalous low-energy deuteron-induced nuclear reactions in metal. The theory is based on the Bose-Einstein condensate (BEC) state occupied by deuterons trapped in a micro/nano-scale metal grain or particle. The theory is capable of explaining most of the experimentally observed results and also provides theoretical predictions, which can be tested experimentally. Scalabilities of the observed effects are discussed based on theoretical predictions. PMID:19440686

Kim, Yeong E

2009-07-01

93

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

94

Integral receiver\\/dehydrator and expansion valve for air conditioning systems  

Microsoft Academic Search

For use in an air conditioning system of the type comprising a refrigerant compressor, a condenser is described connected with the outlet thereof and an evaporator connected with the inlet of the compressor, an integrally contained receiver\\/dehydrator and expansion valve.

Tomasov

1988-01-01

95

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

96

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

97

Intermediate-depth earthquake faulting by dehydration embrittlement with negative volume change.  

PubMed

Earthquakes are observed to occur in subduction zones to depths of approximately 680 km, even though unassisted brittle failure is inhibited at depths greater than about 50 km, owing to the high pressures and temperatures. It is thought that such earthquakes (particularly those at intermediate depths of 50-300 km) may instead be triggered by embrittlement accompanying dehydration of hydrous minerals, principally serpentine. A problem with failure by serpentine dehydration is that the volume change accompanying dehydration becomes negative at pressures of 2-4 GPa (60-120 km depth), above which brittle fracture mechanics predicts that the instability should be quenched. Here we show that dehydration of antigorite serpentinite under stress results in faults delineated by ultrafine-grained solid reaction products formed during dehydration. This phenomenon was observed under all conditions tested (pressures of 1-6 GPa; temperatures of 650-820 degrees C), independent of the sign of the volume change of reaction. Although this result contradicts expectations from fracture mechanics, it can be explained by separation of fluid from solid residue before and during faulting, a hypothesis supported by our observations. These observations confirm that dehydration embrittlement is a viable mechanism for nucleating earthquakes independent of depth, as long as there are hydrous minerals breaking down under a differential stress. PMID:15057828

Jung, Haemyeong; Green II, Harry W; Dobrzhinetskaya, Larissa F

2004-04-01

98

Mass Transfer During Osmotic Dehydration of Pineapple  

Microsoft Academic Search

The diffusion coefficients of water and solutes are important parameters in the analysis, design and optimisation of an osmotic dehydration process. This work estimated by Fick’s Law the diffusion coefficients of water and sucrose during the osmotic dehydration of slices of pineapple fruit in sucrose solution at different temperatures. In addition, it analysed the effect of the change in thickness

L. A. Ramallo; C. Schvezov; R. H. Mascheroni

2004-01-01

99

Synthesis of borasiloxane-based macrocycles by multicomponent condensation reactions in solution or in a ball mill.  

PubMed

Large macrocycles containing imine and borasiloxane links are obtained in polycondensation reactions of 4-formylbenzeneboronic acid, t-Bu(2)Si(OH)(2), and diamines. The multicomponent reactions can be performed in solution or--advantageously--by mechanochemical syntheses in a ball mill. PMID:23164928

Pascu, Mirela; Ruggi, Albert; Scopelliti, Rosario; Severin, Kay

2013-01-01

100

Isoreticular two-dimensional covalent organic frameworks synthesized by on-surface condensation of diboronic acids.  

PubMed

On-surface self-condensation of 1,4-benzenediboronic acid was previously shown to yield extended surface-supported, long-range-ordered two-dimensional covalent organic frameworks (2D COFs). The most important prerequisite for obtaining high structural quality is that the polycondensation (dehydration) reaction is carried out under slightly reversible reaction conditions, i.e., in the presence of water. Only then can the subtle balance between kinetic and thermodynamic control of the polycondensation be favorably influenced, and defects that are unavoidable during growth can be corrected. In the present study we extend the previously developed straightforward preparation protocol to a variety of para-diboronic acid building blocks with the aim to tune lattice parameters and pore sizes of 2D COFs. Scanning tunneling microscopy is employed for structural characterization of the covalent networks and of noncovalently self-assembled structures that form on the surface prior to the thermally activated polycondensation reaction. PMID:22775491

Dienstmaier, Jürgen F; Medina, Dana D; Dogru, Mirjam; Knochel, Paul; Bein, Thomas; Heckl, Wolfgang M; Lackinger, Markus

2012-08-28

101

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

102

An efficient zinc-catalyzed dehydration of primary amides to nitriles.  

PubMed

In the present study, the zinc-catalyzed dehydration of a variety of amides with N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) as a dehydration reagent into the corresponding nitriles has been examined in detail. With the straightforward and commercially available zinc(II)triflate as the precatalyst and MSTFA, an excellent system has been established to afford nitriles in excellent yields and chemoselectivities. After investigation of reaction conditions and the scope and limitations, several efforts were carried out to understand the reaction mechanism. PMID:21956861

Enthaler, Stephan; Inoue, Shigeyoshi

2012-01-01

103

DNA condensation  

Microsoft Academic Search

Recent progress in our understanding of DNA condensation includes the observation of the collapse of single DNA molecules, greater insights into the intermolecular forces driving condensation, the recognition of helix-structure perturbation in condensed DNA, and the increasing recognition of the likely biological consequences of condensation. DNA condensed with cationic liposomes is an efficient agent for the transfection of eukaryotic cells,

Victor A Bloomfield

1996-01-01

104

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.

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

105

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

106

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

107

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...

108

Observations of denitrification and dehydration in the winter polar stratospheres  

NASA Technical Reports Server (NTRS)

It is argued that denitrification of the Arctic stratosphere can be explained by the selective growth and sedimentation of aerosol particles rich in nitric acid. Because reactive nitrogen species moderate the destruction of ozone by chlorine-catalyzed reactions by sequestering chlorine in reservoir species such as ClONO2, the possibility of the removal of reactive nitrogen without dehydration should be allowed for in attempts to model ozone depletion in the Arctic. Indeed, denitrification along with elevated concentrations of reactive chlorine observed in 1989 indicate that the Arctic was chemically primed for ozone destruction without an extended period of temperatures below the frost point, as is characteristic of the Antarctic.

Fahey, D. W.; Kelly, K. K.; Kawa, S. R.; Tuck, A. F.; Loewenstein, M.

1990-01-01

109

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

110

Dehydration of cytosine monohydrate at physiological temperatures  

SciTech Connect

Neutron diffraction, thermogravimetric, and mass spectrographic measurements have been used to show that cytosine monohydrate loses its water of hydration at physiological temperatures (approx. = 37/sup 0/C) and converts to cytosine. The ''activation energy'' for the dehydration process has been determined from isothermal weight curves and is 27.1 +/- 0.6 kcal . mol/sup -1/. It is suggested that pyrimidine dehydration may be involved in structural changes in DNA.

Martel, P.; Powell, B.M.

1983-01-01

111

Iron sulfide catalyzed redox/condensation cascade reaction between 2-amino/hydroxy nitrobenzenes and activated methyl groups: a straightforward atom economical approach to 2-hetaryl-benzimidazoles and -benzoxazoles.  

PubMed

Iron sulfide generated in situ from elemental sulfur and iron was found to be highly efficient in catalyzing a redox/condensation cascade reaction between 2-amino/hydroxy nitrobenzenes and activated methyl groups. This method represents a straightforward and highly atom economical approach to 2-hetaryl-benzimidazoles and -benzoxazoles. PMID:23249371

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

2013-01-01

112

Fragmentation of chloroperoxides: hypochlorite-mediated dehydration of hydroperoxyacetals to esters  

PubMed Central

Hypochlorites efficently dehydrate hydroperoxyacetals to furnish the corresponding esters. The reaction, which can be accomplished with stoichometric Ca(OCl)2 or with catalytic amounts of t-BuOCl, appears to involve formation and heterolytic fragmentation of secondary chloroperoxides, species not previously described in solution chemistry. PMID:20865135

Fisher, Thomas J.; Dussault, Patrick H.

2010-01-01

113

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

114

Dehydration kinetics of talc at 1 bar  

NASA Technical Reports Server (NTRS)

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

Ganguly, J.; Bose, K.

1991-01-01

115

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

116

Leveraging the micellar effect: gold-catalyzed dehydrative cyclizations in water at room temperature.  

PubMed

The first examples of gold-catalyzed cyclizations of diols and triols to the corresponding hetero- or spirocycles in an 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; Krause, Norbert; Lipshutz, Bruce H

2014-02-01

117

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

118

Dehydration mechanism of optical clearing in tissue.  

PubMed

Previous studies identified various mechanisms of light scattering reduction in tissue induced by chemical agents. Our results suggest that dehydration is an important mechanism of optical clearing in collagenous and cellular tissue. Photographic and optical coherence tomography images indicate that air-immersed skin and tendon specimens become similarly transparent to glycerol-immersed specimens. Transmission electron microscopy images reveal that dehydration causes individual scattering particles such as collagen fibrils and organelles to become more densely packed, but does not significantly alter size. A heuristic particle-interaction model predicts that the scattering particle volume fraction increase can contribute substantially to optical clearing in collagenous and cellular tissue. PMID:16965145

Rylander, Christopher G; Stumpp, Oliver F; Milner, Thomas E; Kemp, Nate J; Mendenhall, John M; Diller, Kenneth R; Welch, A J

2006-01-01

119

Organobase-catalyzed three-component reactions for the synthesis of 4H-2-aminopyrans, condensed pyrans and polysubstituted benzenes  

PubMed Central

Summary Novel routes for the preparation of 2-amino-4H-pyran-3-carbonitrile 9, amino-arylbenzoic acid ester derivatives 13a,b, 2-aminotetrahydro-4H-chromene-3-carbonitrile 18, 3-amino-4-cyanotetrahydronaphthalene-2-carboxylic acid ester 26 and 4-amino-3,5-dicyanophthalic acid ester derivatives 37a–c were developed. The synthetic methods utilize one-pot reactions of acetylene carboxylic acid esters, ?,?-unsaturated nitriles and/or active methylenenitriles in the presence of L-proline or DABCO. Plausible mechanisms are suggested for the formation of the products. Finally, these compounds were used for the efficient synthesis of 6-amino-5-cyanonicotinic acid ester derivatives 31a,b, ethyl 4-amino-5H-pyrano[2,3-d]pyrimidine-6-carboxylates 33a,b, 4-amino-6H-pyrrolo[3,4-g]quinazoline-9-carbonitrile 39, and 1,7-diamino-6-(N'-hydroxycarbamimidoyl)-3-oxo-5-phenyl-3H-isoindole-4-carboxylate (40). PMID:24454567

Moustafa, Moustafa Sherief; Selim, Maghraby Ali; Mosallam, Ahmed Mohamed

2014-01-01

120

Reactions in gas phase and condensed phase C6F5X (X = NCO, CH2CN) triggered by low energy electrons.  

PubMed

Electron attachment to gas phase perfluorophenylisocyanate (C(6)F(5)NCO) and perfluorophenyloacetonitrile (C(6)F(5)CH(2)CN) generates metastable parent anions within a very narrow resonance close to zero energy. At higher energies (2-7 eV), dissociative electron attachment (DEA) resonances are present, associated with the rupture of the C(6)F(5)-X bond (X = NCO, CH(2)CN) with the excess electron finally localised on either of the two fragments. The most intense fragment ion from C(6)F(5)CH(2)CN (M) is (M - HF)(-), which arises from the loss of a neutral HF from the transient anion and requires the concerted cleavage of two bonds and formation of a new molecule (HF). Most remarkably, this rather complex DEA reaction is by about two orders of magnitude more intense than the single bond cleavages (C(6)F(5)-X) leading to the complementary DEA reactions C(6)F(5) + X(-) and C(6)F(5)(-) + X. From both condensed molecules we observe desorption of F(-) and CN(-) and, additionally, O(-) from C(6)F(5)NCO. The desorption yields also show a resonant behaviour with the peak maxima in the range 8-12 eV, i.e., near or above the ionization energy, indicating that in electron stimulated desorption (ESD) highly excited resonances are involved. Ab initio calculations are performed in order to get information on the shape and energy of the molecular orbitals involved in low energy (<2 eV) electron attachment. PMID:19551199

Dabkowska, Iwona; Flosadóttir, Helga Dögg; Orzol, Mario; Ptasinska, Sylwia; Bald, Ilko; Ingólfsson, Oddur; Illenberger, Eugen

2009-07-14

121

Polynuclear copper(II) pyrazolate complexes: temperature-dependent protonolysis reactions, crystal structures and high catalytic activity toward the condensation of nitriles with 2-aminoalcohol.  

PubMed

Reaction of Cu(OAc)2·H2O and 1H-pyrazole-3,5-dicarboxylic acid dimethyl ester (Hdcmpz) in MeOH at room temperature afforded one tetranuclear Cu(II)/pyrazolate complex [{Cu2(?-OAc)2}2(?-dcmpz)2(?-OAc)2] (1) in 89% yield. The similar reaction in refluxing MeOH produced a hexanuclear metallamacrocyclic Cu(II)/pyrazolate complex [{Cu(?-dcmpz)}2(?-OMe)2]3 (2) in 85% yield. Treatment of the same components under solvothermal conditions resulted in the formation of another tetranuclear Cu(II)/pyrazolate/carboxylate complex [{Cu(MeOH)}4(?-mcccpz)4] (3, Hmcccpz = 5(3)-(methoxycarbonyl)-1H-pyrazole-3(5)-carboxylic acid) in 30% yield. The mcccpz(2-) ion in 3 was in situ generated via the hydrolysis of one of two esters on dcmpz ligand. Complexes 1-3 were characterized by elemental analysis, IR and single-crystal X-ray diffraction. An X-ray analysis revealed that 1 contains two {Cu(?-OAc)}2 fragments that are interconnected by two ?-?(2),?(2)-dcmpz(-) ligands and two ?-?(1),?(1)-OAc(-) ions, forming a unique tetrameric structure. Complex 2 is composed of three {Cu(?-dcmpz)}2 fragments linked by three pairs of ?-OMe(-) anions, forming a metallamacrocyclic crown structure. 3 consists of four {Cu(MeOH)} fragments linked by two pairs of ?-?(1),?(2)-mcccpz(2-) ligands, forming a tetrameric [2 × 2] grid-like structure. Complexes 1-3 displayed high catalytic activity toward the condensation of nitriles with 2-aminoalcohol under solvent-free conditions to produce various 2-oxazolines. PMID:24085112

Wang, Ling; Guo, Bin; Li, Hong-Xi; Li, Qi; Li, Hai-Yan; Lang, Jian-Ping

2013-11-28

122

Identification of 4-methylspinaceamine, a pictet-spengler condensation reaction product of histamine with acetaldehyde, in fermented foods and its metabolite in human urine.  

PubMed

Previous study demonstrated that 4-methylspinaceamine (4-methyl-4,5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridine), a Pictet-Spengler condensation reaction product of histamine with acetaldehyde, is present in human urine. The current study sought to determine whether 4-methylspinaceamine is present in fermented foods; its presence might be expected since both histamine and acetaldehyde are often present in these foods. Soy sauce, fish sauce, cheese, and shao hsing wine (Chinese wine) were found to contain 4-methylspinaceamine. The concentration of 4-methylspinaceamine excreted in human urine was greatly elevated after ingestion of a meal containing soy sauce as a dietary source of 4-methylspinaceamine, demonstrating that the level of 4-methylspinaceamine in human urine was affected by dietary foods. In addition, a metabolite of 4-methylspinaceamine in human urine was investigated. An enhanced peak in the HPLC chromatogram of human urine samples after ingestion of 4-methylspinaceamine-containing foods was observed. A peak at the same retention time was also observed from a human urine sample after administration of 4-methylspinaceamine, suggesting that the peak was due to a metabolite. By comparison with the newly synthesized authentic compound, the metabolite was identified as 1,4-dimethylspinaceamine. PMID:16939357

Ohya, Takeshi

2006-09-01

123

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

124

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

125

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

126

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

127

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

128

Dehydration in the Winter Arctic Tropopause Region  

NASA Technical Reports Server (NTRS)

Recent work has shown that limited amounts of tropospheric air can penetrate as much as 1 km into the middleworld stratosphere during the arctic winter. This, coupled with temperatures that are cold enough to produce saturation mixing ratios of less than 5 ppmv at the tropopause, results in stratospheric cloud formation and upper tropospheric dehydration. Even though these "cold outbreaks" occupy only a small portion of the area in the arctic (1-2%), their importance is magnified by an order of magnitude because of the air flow through them. This is reinforced by evidence of progressive drying through the winter measured during SOLVE-1. The significance of this process lies in its effect on the upper tropospheric water content of the middle and high latitude tropopause region, which plays an important role in regulating the earth's radiative balance. There appears to be significant year-to-year variability in the incidence of the cold outbreaks. This work has two parts. First, we describe case studies of dehydration taken from the SOLVE and SOLVE2 aircraft sampling missions during the Arctic winters of 2000 and 2003 respectively. Trajectory based microphysical modeling is employed to examine the sensitivity of the dehydration to microphysical parameters and the nature of sub-grid scale temperature fluctuations. We then examine the year-to-year variations in potential dehydration using a trajectory climatology.

Pfister, Leonhard; Jensen, Eric; Podolske, James; Selkirk, Henry; Anderson, Bruce; Avery, Melody; Diskin. Glenn

2004-01-01

129

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

130

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

131

Pervaporation dehydration of isopropanol with chitosan membranes  

Microsoft Academic Search

Homogeneous and composite chitosan based membranes were prepared by the solution casting technique. The membranes were investigated for the pervaporation dehydration of isopropanol-water systems. The effects of feed concentration and temperature on the separation performance of the membranes were studied. In terms of the pervaporation separation index (PSI), the composite membrane was more productive than the homogeneous membrane for pervaporation

M. Ghazali; M. Nawawi; Robert Y. M. Huang

1997-01-01

132

Optimization of osmotic dehydration of cantaloupe using desired function methodology  

Microsoft Academic Search

Our objective was to optimize the osmotic dehydration of the cantaloupe using the desired function methodology. Cantaloupe cylinders were cut and weighted, initial humidity and °Brix were measured, then four cylinders were osmo-dehydrated in solutions of sucrose of give concentration and temperature by a stipulated time. The conditions of dehydration were established by means of a central rotable composite design

Otoniel Corzo; Eddie R. Gomez

2004-01-01

133

Amine catalyzed condensation of tetraethylorthosilicate  

NASA Technical Reports Server (NTRS)

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

Jones, S.

2001-01-01

134

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

Microsoft Academic Search

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

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

2011-01-01

135

Kinetic analysis of the malonyl coenzyme A decarboxylation and the condensation reaction of fatty acid synthesis. Application to the study of malonyl coenzyme A inactivated chicken liver fatty acid synthetase.  

PubMed

A kinetic analysis of the decarboxylation of malonyl-CoA and the condensation--CO2 exchange reaction of fatty acid synthesis has been carried out. The analysis supported by experimental evidence defines conditions under which the decarboxylation of malonyl-CoA quantitatively reflects the activity for the condensation reaction between enzyme-bound acyl and malonyl groups. NADP+ decreases the release of 14CO2 from radiolabeled malonyl-CoA by lowering the rates of the processes leading to the formation of triacetic acid lactone. For accurate measurements, the enzyme concentration should be less than 200 micrograms/mL, and malonyl-CoA/enzyme ratios should be 200 or less. Short reaction periods (1 min or less) and inclusion of NADP+ (100 microM) enhance the accuracy of measurements. These analyses have been used to explain the mechanism of malonyl-CoA mediated inactivation of chicken liver fatty acid synthetase and are appropriate for determining the functional condensing site of the polyfunctional polypeptide chains comprising the dimeric enzyme. PMID:7260045

Srinivasan, K R; Kumar, S

1981-06-01

136

Dehydration of water-pyridine mixtures by pervaporation  

SciTech Connect

The pervaporation technique, in which the liquid feed mixture is maintained in contact with one side of a nonporous membrane and the permeate is continuously removed from the other side as a vapor, is one of the new methods to attain separation of azeotropic mixtures, structural isomers, or even to displace the equilibrium of chemical reactions. Several ion-exchange and neutral membranes were examined in the pervaporation of water-pyridine mixtures. Carboxylic and sulfonic ion-exchange membranes were used with hydrogen counterion and additionally with trimethylammonium, triethylammonium, and tributylammonium counterions. All membranes were selective to water, but the transport mode and selectivity properties of membranes were dependent on both the character of the ion-exchange group and the ionic form of the membrane. The results obtained suggest that pervaporation of water-pyridine mixtures could be used with standard distillation in the large-scale dehydration process of pyridine.

Kujawski, W. (N. Copernicus Univ., Torun (Poland) Centre National de la Recherche Scientifique-UA 494, Nancy (France)); Nguyen, T.Q.; Neel, J. (Centre National de la Recherche Scientifique-UA 494, Nancy (France))

1991-08-01

137

Excitonic Condensates  

NASA Astrophysics Data System (ADS)

Exciton condensation may occur not only in semiconductors, but also in mixed-valent compounds(H. J. Leder, Solid State Commun. 27), 579 (1978). Whereas the excitonic condensate in a semiconductor must be created artificially using optical pumping, the excitonic condensate in a mixed-valent compound is already built in by nature. This makes mixed-valent compounds ideal systems for studying the optical properties of excitonic condensates(V. Yu. Irkin and M. I. Katsnel'son, Zh. Eksp. Teor. Fiz. 90), 1080 (1986) [Sov. Phys. JETP 63, 631 (1986)]. Three surprising manifestations of exciton condensation in mixed-valent compounds are discussed in this talk: 1) electronic ferroelectricity, 2) ferroelectric resonance, and 3) a nonvanishing susceptibility for second-harmonic generation. A number of experiments are proposed which can give evidence for exciton condensation in mixed-valent compounds.

Portengen, T.

1998-03-01

138

Microwave Finish Drying of Osmotically Dehydrated Cranberries  

Microsoft Academic Search

Combined microwave and hot-air drying characteristics was studied for the drying of cranberries that had been previously partially dehydrated by osmosis in a high fructose corn syrup (76°Brix). A 750 W 2450 MHz microwave oven was used to dry cranberry samples from 57% to 15% moisture content using three different power densities (0.75, 1.0, 1.25 W\\/g of initial cranberries) and two different power

C. Beaudry; G. S. V. Raghavan; T. J. Rennie

2003-01-01

139

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

140

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

141

Dehydration of methyl phenyl carbinol catalyzed by modified active aluminum oxide  

Microsoft Academic Search

The effect of modification with metal salts and acids on the acid-base characteristics and the catalytic properties of active\\u000a aluminum oxide in the reaction of methyl phenyl carbinol dehydration to styrene was studied using the IR spectroscopy of adsorbed\\u000a base molecules. The surface treatment of ?-Al2O3 with chromium and nickel cations decreased the catalyst activity because of the occurrence of

A. A. Lamberov; Kh. Kh. Gil’manov; S. R. Egorova; S. V. Trifonov

2007-01-01

142

Modeling and optimization of catalytic dehydration of ethanol to ethylene using central composite design  

Microsoft Academic Search

The central composite design in the modeling and optimization of catalytic dehydration of ethanol to ethylene was performed\\u000a to improve the ethylene yield. A total of 20 experiments at random were conducted to investigate the effect of reaction temperature,\\u000a Si\\/Al ratios of H-ZSM-5 catalyst and liquid hourly space velocity (LHSV) on the ethylene yield. The results show that the\\u000a relationship

Haining Kong; Ershi Qi; Gang Li; Shuguang He; Xian Zhang

2009-01-01

143

Dehydration of isobutanol to isobutene in a slurry reactor  

SciTech Connect

The April 1990 Alternative Fuels Proposal to the Department of Energy involved the development of new technology, based on the liquid phase process, for conversion of coal-derived synthesis gas to oxygenated hydrocarbon fuels, fuel additives, and fuel intermediates. The objective of this work was to develop a slurry reactor based process for the dehydration of isobutanol to isobutene. The isobutene can serve as a feedstock for the high octane oxygenated fuel additive methyl tertiary-butyl either (MTBE). Alumina catalysts were investigated because of their wide use as a dehydration catalyst. Four commercially available alumina catalysts (Catapal B, Versal B, Versal GH, and Al-3996R) were evaluated for both activity and selectivity to the branched olefin. All four catalysts demonstrated conversions greater than 80% at 290 C, while conversions of near 100% could be obtained at 330 C. The reaction favors low pressures and moderate to low space velocities. A yield of 0.90 mole isobutene per mole reacted isobutanol or better was obtained at conversions of 60--70% and higher. From 75 to 98% conversion, the four catalysts all provide isobutene yields ranging from 0.92 to 0.94 with the maximum occurring around 90% conversion. At low conversions, the concentration of diisobutyl ether becomes significant while the concentration of linear butenes is essentially a linear function of isobutanol conversion. Doping the catalyst with up to 0.8 wt % potassium showed a modest increase in isobutene selectivity; however, this increase was more than offset by a reduction in activity. Investigations using a mixed alcohols feed (consistent with isobutanol synthesis from syngas) demonstrated a small increase in the C4 iso-olefin selectivity over that observed for a pure isobutanol feed. 55 refs.

Latshaw, B.E.

1994-02-01

144

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

145

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

146

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

PubMed Central

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

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

1997-01-01

147

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

148

New experimental data on the antigorite dehydration in silica enriched serpentinite  

NASA Astrophysics Data System (ADS)

There is a growing body of evidences for complex interaction between highly reactive fluids and ultramafic lithologies. Silica metasomatism, for example, can occur at the basement of slow-spreading mid-ocean ridges and during prograde metamorphism of chaotically intermixing in mélange zones of ultramafic rocks, metasediments and metabasites in subduction settings. The resulting assemblage diagnostic of metaperidotites that experienced silica metasomatism are talc-schist and talc-bearing serpentinite. These lithologies may hence be common in subduction settings and will undergo different dehydration reactions. Antigorite and talc will react at lower temperature than the terminal antigorite dehydration. Although this reaction is not expected to be as important in the transfer of water to mantle depth as the breakdown of antigorite, it represents nevertheless a dehydration event in subduction zones that has not been considered so far. We anticipate that this reaction might be particularly important for the fore-arc mantle wedge. Piston cylinder experiments were performed to constrain the pressure and temperature conditions for two high-pressure antigorite dehydration reactions found in silica-enriched serpentinites from Cerro del Almirez (Nevado-Filábride Complex, Betic Cordillera, southern Spain) [1]. At 630-660°C and pressures greater than 1.6 GPa, antigorite first reacts with talc to form orthopyroxene ± chlorite + fluid. We show that orthopyroxene + antigorite is restricted to high-pressure metamorphism of silica-enriched serpentinite. This uncommon assemblage is helpful in constraining metamorphic conditions in cold subduction environments, where antigorite serpentinites have no diagnostic assemblages over a large range in PT space [2,3]. The second dehydration reaction leads to the breakdown of antigorite to olivine + orthopyroxene + chlorite + fluid. The maximum stability of antigorite is found at 680°C at 1.9 GPa, which also corresponds to the maximum pressure limit for tremolite coexisting with olivine + orthopyroxene [4]. [1] Trommsdorff, López Sánchez-Vizcaíno, Gómez-Pugnaire, and Müntener (1998), Contrib Mineral Petr 132 139-148. [2] Hermann, Müntener, and Scambelluri, (2000) Tectonophysics 327, 225-238. [3] Scambelluri, Müntener, Hermann, Piccardo, and Trommsdorff, Geology 23, 459-462. [4] Padrón-Navarta, Hermann, Garrido, López Sánchez-Vizcaíno, and Gómez-Pugnaire (2010), Contrib Mineral Petr 159, 25-42.

Padrón-Navarta, José Alberto; Hermann, Jörg; Garrido, Carlos J.; López Sánchez-Vizcaíno, Vicente; Gómez-Pugnaire, María. Teresa

2010-05-01

149

Charged Condensation  

E-print Network

We consider Bose-Einstein condensation of massive electrically charged scalars in a uniform background of charged fermions. We focus on the case when the scalar condensate screens the background charge, while the net charge of the system resides on its boundary surface. A distinctive signature of this substance is that the photon acquires a Lorentz-violating mass in the bulk of the condensate. Due to this mass, the transverse and longitudinal gauge modes propagate with different group velocities. We give qualitative arguments that at high enough densities and low temperatures a charged system of electrons and helium-4 nuclei, if held together by laboratory devices or by force of gravity, can form such a substance. We briefly discuss possible manifestations of the charged condensate in compact astrophysical objects.

Gregory Gabadadze; Rachel A. Rosen

2007-06-15

150

A new one-pot three-component condensation reaction for the synthesis of 2,3,4,6-tetrasubstituted pyridines.  

PubMed

The one-pot three-component condensation of a beta-ketoester, ammonia and an alkynone in the presence of a Brønsted or Lewis acid or Amberlyst 15 ion exchange resin provided 2,3,6-trisubstituted or 2,3,4,6-tetrasubstituted pyridines directly in good yield and with total regiocontrol. PMID:12196948

Bagley, Mark C; Dale, James W; Bower, Justin

2002-08-21

151

Continuous-flow hydration–condensation reaction: Synthesis of ?,?-unsaturated ketones from alkynes and aldehydes by using a heterogeneous solid acid catalyst  

PubMed Central

Summary A simple, practical and efficient continuous-flow hydration–condensation protocol was developed for the synthesis of ?,?-unsaturated ketones starting from alkynes and aldehydes by employing a heterogeneous catalyst in a flow microwave. The procedure presents a straightforward and convenient access to valuable differently substituted chalcones and can be applied on multigram scale. PMID:22238547

Bootwicha, Teerawut; Baars, Hannah; Sugiono, Erli

2011-01-01

152

Biomass energy analysis for crop dehydration  

SciTech Connect

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

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

1994-12-31

153

Cryoprotective dehydration is widespread in Arctic springtails.  

PubMed

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

Sørensen, Jesper Givskov; Holmstrup, Martin

2011-08-01

154

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

155

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...

156

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

157

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

158

40 CFR 63.1275 - Glycol dehydration unit process vent standards.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 true Glycol dehydration unit process vent standards...Facilities § 63.1275 Glycol dehydration unit process vent standards...section applies to each glycol dehydration unit subject to this...

2010-07-01

159

40 CFR 63.1275 - Glycol dehydration unit process vent standards.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Glycol dehydration unit process vent standards...Facilities § 63.1275 Glycol dehydration unit process vent standards...section applies to each glycol dehydration unit subject to this...

2011-07-01

160

40 CFR 63.765 - Glycol dehydration unit process vent standards.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Glycol dehydration unit process vent standards...Facilities § 63.765 Glycol dehydration unit process vent standards...section applies to each glycol dehydration unit subject to this...

2010-07-01

161

40 CFR 63.765 - Glycol dehydration unit process vent standards.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Glycol dehydration unit process vent standards...Facilities § 63.765 Glycol dehydration unit process vent standards...section applies to each glycol dehydration unit subject to this...

2011-07-01

162

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

163

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

164

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

165

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

166

Reactions on a surface. 1. Condensation of 3-methyl-3-buten-1-ol with carbonyl compounds on SiO 2 and Al 2 O 3  

Microsoft Academic Search

3-Methyl-3-buten-1-ol reacts with various aldehydes and ketones on silica gel and Al2O3 surfaces in the absence of solvents and conventional catalysts for this reaction to form derivatives of di- and tetrahydropyrans.

U. G. Ibatullin; Yu. V. Pavlov; M. G. Safarov

1989-01-01

167

Hydration-dehydration interactions between glycine and anhydrous salts: Implications for a chemical evolution of life  

NASA Astrophysics Data System (ADS)

Polymerizations of organic monomers including amino acids, nucleotides and monosaccharides are essential processes for chemical evolution of life. Since these reactions proceed with "dehydration" reactions, they are possibly promoted if combined with thermodynamically favorable "hydration" reactions of minerals and salts. To test the possibility, we conducted heating experiments of the simplest amino acid "glycine (Gly)" mixed with four simple anhydrous salts (MgSO 4, SrCl 2, BaCl 2 and Li 2SO 4) at 140 °C up to 20 days. Gly polymerization was strongly promoted by mixing with the salts in the order of MgSO 4 > SrCl 2 > BaCl 2 > Li 2SO 4. Up to 6-mer of Gly polymers were synthesized in the Gly-MgSO 4 mixture, and a total yield of Gly polymers attained about 7% of the initial amount of Gly by the 20 days heating. The total yield was about 200 times larger than that from the heating of Gly alone. XRD measurements of the Gly-MgSO 4 mixture revealed the generation of MgSO 4 monohydrate during Gly polymerization. These observations indicate that Gly polymerization was promoted by the salt hydrations through the hydration-dehydration interactions. Based on the observations, we tried to find a relationship between thermodynamic characteristics of the interactions and the promotion effects of each salt on Gly polymerization. It was found that the salts having lower hydration ? rG0 (easier to hydrate) promote Gly polymerization more strongly. The relationship was used to estimate promotion effects of simple oxide minerals on Gly polymerization. The estimations were consistent with previous observations about the effects of these minerals on Gly polymerization. The fact suggests that the hydration-dehydration interactions between amino acids and minerals are an important mechanism for amino acids' polymerizations on minerals.

Kitadai, Norio; Yokoyama, Tadashi; Nakashima, Satoru

2011-11-01

168

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

169

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

170

Dehydration and ionic conductance quantization in nanopores  

E-print Network

There has been tremendous experimental progress in the last decade in identifying the structure and function of biological pores (ion channels) and fabricating synthetic pores. Despite this progress, many questions still remain about the mechanisms and universal features of ionic transport in these systems. In this paper, we examine the use of nanopores to probe ion transport and to construct functional nanoscale devices. Specifically, we focus on the newly predicted phenomenon of quantized ionic conductance in nanopores as a function of the effective pore radius - a prediction that yields a particularly transparent way to probe the contribution of dehydration to ionic transport. We study the role of ionic species in the formation of hydration layers inside and outside of pores. We find that the ion type plays only a minor role in the radial positions of the predicted steps in the ion conductance. However, ions with higher valency form stronger hydration shells, and thus, provide even more pronounced, and therefore, more easily detected, drops in the ionic current. Measuring this phenomenon directly, or from the resulting noise, with synthetic nanopores would provide evidence of the deviation from macroscopic (continuum) dielectric behavior due to microscopic features at the nanoscale and may shed light on the behavior of ions in more complex biological channels.

Michael Zwolak; James Wilson; Massimiliano Di Ventra

2010-05-14

171

Rate of Nucleation in Condensed Systems  

Microsoft Academic Search

On the basis of the nucleation theory developed by Volmer, Becker, and co-workers, and the theory of absolute reaction rates, an expression is derived for the absolute rate of nucleation in condensed systems.

D. Turnbull; J. C. Fisher

1949-01-01

172

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

173

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...

174

Neuropsychological Performance, Postural Stability, and Symptoms After Dehydration  

PubMed Central

Context: Dehydration and concussion are common in athletic performance. Some experts have speculated that dehydration may negatively influence performance on tests commonly used for concussion assessment. Objective: To determine how the signs and symptoms, neuropsychological performance, and postural stability are affected by dehydration. Design: Repeated-measures design assessing subjects in the euhydrated and dehydrated conditions. Setting: Sports Medicine Research Laboratory. Patients or Other Participants: Twenty-four healthy, male recreational athletes participated in the study. Intervention(s): Subjects participated in 2 counterbalanced sessions (euhydrated and dehydrated) separated by at least 7 days. Subjects were dehydrated using fluid restriction and an exercise task. No direct intervention was provided for the euhydrated condition. Main Outcome Measure(s): We used the Standardized Assessment of Concussion to test mental status, the Automated Neuropsychological Assessment Metrics (ANAM) to evaluate neuropsychological performance, the NeuroCom Sensory Organization Test and Balance Error Scoring System to test postural stability, the Graded Symptom Checklist to assess symptom presence and severity in our participants, and urine specific gravity and body mass to determine hydration status. Results: No differences were noted for the Standardized Assessment of Concussion, total Balance Error Scoring System errors, composite Sensory Organization Test, and composite ANAM scores between conditions. Subjects in the dehydrated condition had significant deterioration in visual memory (t23 = 2.130, P < .001) and fatigue measures (t23 = ?7.880, P < .001) as assessed by ANAM. The dehydrated condition resulted in subjects reporting a significantly higher number (t23 = ?8.585, P < .001) and severity (t23 = ?7.673, P < .001) of symptoms than the euhydrated subjects on the Graded Symptom Checklist. Conclusions: Our results suggest that moderate dehydration (?2.5 ± 0.63%) significantly influenced the self-report of symptoms commonly associated with concussion. Dehydration resulted in a deterioration of visual memory and increases in the self-report of fatigue. Despite these findings, dehydration did not affect other neuropsychological and postural stability objective testing measures for concussion. PMID:17597946

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

2007-01-01

175

Micronutrient flow to the osmotic solution during grapefruit osmotic dehydration  

Microsoft Academic Search

The purpose of this work was to quantify the flow of soluble micronutrients, such as acids, minerals and pectins, from the grapefruit to the osmotic solution (OS) used to dehydrate the fruit when recycling it in successive osmotic dehydration (OD) operations, without reconcentrating. OD was carried out for 3h at 30°C with an OS:fruit rate 5:1, using a 55 °Brix

R. Peiró; V. M. C. Dias; M. M. Camacho; N. Martínez-Navarrete

2006-01-01

176

Quality evaluation of onion (Allium cepa) cultivars for dehydration  

E-print Network

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

Talley, Linda Jean

1979-01-01

177

Effects of Fixation and Dehydration Procedures on Marine Nematodes  

PubMed Central

Different combinations of fixation and dehydration procedures for the preparation of permanent mounts of marine nematodes of the subfamily Oncholaiminae were tested and compared. Qualitatively, the best specimens resulted from Seinhorst's killing method and fixation in FAA; the dehydration procedure was of less significance. Quantitatively, no significant modification of measurements resulted from any of the methods used. Sources of error in measurements are discussed. PMID:19325668

Timm, R. W.; Hackney, T.

1969-01-01

178

Seawater drinking restores water balance in dehydrated harp seals.  

PubMed

The purpose of this study was to answer the question of whether dehydrated harp seals (Phoca groenlandica) are able to obtain a net gain of water from the intake of seawater. Following 24 h of fasting, three subadult female harp seals were dehydrated by intravenous administration of the osmotic diuretic, mannitol. After another 24 h of fasting, the seals were given 1,000 ml seawater via a stomach tube. Urine and blood were collected for measurement of osmolality and osmolytes, while total body water (TBW) was determined by injections of tritiated water. In all seals, the maximum urinary concentrations of Na(+) and Cl(-) were higher than in seawater, reaching 540 and 620 mM, respectively, compared to 444 and 535 mM in seawater. In another experiment, the seals were given ad lib access to seawater for 48 h after mannitol-induced hyper-osmotic dehydration. In animals without access to seawater, the mean blood osmolality increased from 331 to 363 mOsm kg(-1) during dehydration. In contrast, the blood osmolality, hematocrit and TBW returned to normal when the seals were permitted ad lib access to seawater after dehydration. In conclusion, this study shows that harp seals have the capacity to gain net water from mariposa (voluntarily drinking seawater) and are able to restore water balance after profound dehydration by drinking seawater. PMID:17375309

How, Ole-Jakob; Nordøy, Erling S

2007-07-01

179

Dehydration softening of serpentine as a trigger of intermediate-depth earthquakes  

NASA Astrophysics Data System (ADS)

A popular hypothesis for the occurrence of double seismic zones in subducting slabs is dehydration embrittlement of serpentinized mantle. Deformation experiments of serpentinites using gas-medium apparatus demonstrated the role of pore pressure in the ductile-to-brittle transition at the dehydration temperature (e.g., Raleigh and Paterson, 1965, JGR). However, it is questionable if the same mechanism could be effective in subducting slabs at the depth. Deformation experiments of serpentinites have been also conducted at higher pressure using multi-anvil and Griggs-type apparatus but little is known about the effects of dehydration reaction on the mechanical behavior of serpentinite. We conducted deformation experiments of antigorite-serpentinite (Oeyama ultramafic body, Japan). Cylindrical samples of serpentinite with the diameter of 10 mm and the length of 15 mm were jacketed in Ag tubes and disks. "Slow" and "fast" experiments were conducted at strain rates of 3.3x10-5 sec -1 and 2x10-4 sec-1, respectively. Axial compression tests were conducted at 800 MPa confining pressure using a solid-medium deformation apparatus. The dehydration temperature is about 650 oC at this pressure. Antigorite was hard at 500oC and not yielded up to 900 MPa differential stress. The experimental run at 700oC without pre-heating is characterized by strain hardening. The sample was deformed by foliation-parallel slip, kinking, and micro-faulting of antigorite. On the contrary, samples deformed at 700oC after static heating showed drastic weakening and steady creep behaviors. A velocity step test indicated that the flow stress is insensitive to the strain rate. The deformed samples contain forsterite and enstatite in the antigorite matrix. Antigorite changed in color from dark green to pink, possibly due to highly oxidized atmosphere resulting from free water release. Intergranular pores were well developed. No microcracks or microfaults were observed. No evidence for intracrystalline slip was obtained in the SEM-EBSD analysis. Significant volume loss in the samples suggests compaction and escape of water during deformation experiments. Mechanical behaviors and microstructural features of the pre-heated samples both indicated that the dominant deformation mechanism was cataclastic flow and compaction of reaction products. The reacted samples showed "dehydration softening" rather than "embrittlement". In contrast, the same antigorite-serpentinite deformed in a gas-medium apparatus at a low confining pressure (200 MPa) exhibited a semi-brittle behavior. This fact suggests that dehydration embrittlement is only effective at the shallow to middle crustal levels. In the subducting slabs, strain localization at the serpentinized mantle due to dehydration softening and high fluid pressure caused by pore collapse possibly trigger earthquakes in surrounding peridotite mantle.

Shimizu, I.; Watanabe, Y.; Michibayashi, K.; Uehara, S.; Takahashi, M.; Katsuta, N.

2011-12-01

180

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

181

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

182

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

183

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

PubMed

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

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

2015-01-01

184

Condensation heat transfer  

NASA Astrophysics Data System (ADS)

The paper gives a brief description of some of the better understood aspects of condensation heat transfer and includes discussion of the liquid-vapour interface, natural and forced convection laminar film condensation and dropwise condensation.

Rose, J. W.

185

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!"

Hartman, Monica

2007-12-01

186

Effect of elevated stress and temperature on smectite dehydration in subducting sediments - an experimental approach  

NASA Astrophysics Data System (ADS)

Smectite-rich subduction inputs have been in the focus of convergent margin researchers because of their mechanical weakness, their ability to store water in interlayer sites and to release it at greater depth. The release of bound water in smectite during the transition to illite is widely acknowledged to cause the omnipresent fluid freshening at convergent margins. Freshened fluids are often considered as tracer for lateral fluid flow because illitization occurs at greater depths with temperatures >60°C. Instead, laboratory experiments showed that smectite is able to dehydrate partially when an effective stress level of ~1.3 MPa is exceeded. This observation is still poorly constrained when regarding the hydrogeochemistry of subduction zones. To shed light on this process the set-up of a backpressured uniaxial consolidation apparatus (hydrothermal oedometer) was chosen, which provides a large spectrum of pressure (P) and temperature (T) conditions. Three hydrothermal consolidation tests were conducted at constant temperatures of 20°C, 60°C and 100°C up to stresses of 70 MPa. The specimen used was a smectite-rich silty claystone to emphasize dehydration reactions. It is mineralogically similar to smectite-rich end members from the Nankai Trough subduction zone (Japan), Barbados accretionary wedge and Costa Rica margin. The fluids expelled at different stress intervals during the compaction tests were analyzed for major and trace elements to evaluate potential fluid-rock interaction with increasing PT conditions in the shallow subduction zone. The results confirm that smectite dehydration starts at stresses as low as ~2 MPa. However, the interlayer collapse can be also related to the decreasing availability of water in the water-rock system. This assumption is favored by the good accordance with literature data of the experimentally determined relationship between smectite's basal spacing and the water-smectite mass ratio. In addition, the data from the room-temperature experiment was sufficient to formulate for the first time a relationship between the water-rock mass ratio (w/r) and the dehydrated smectite fraction in the sediment. This allows a holistic view of 3 different depth-temperature stages of smectite dehydration in the subduction zone. In shallow parts (approx. <250 mbsf) and in overpressured layers where the sediment is able to maintain w/r mass ratios greater than 0.44 g/g and the temperature is low no smectite dehydration occurs. At greater depth where w/r mass ratios are smaller 0.44 g/g dehydration generates low chlorinity fluids. The fluid freshening is associated with less K and Mg and increased concentrations of Na as well as volatile elements (B, Li, Si). This is caused by the change in cation selectivity towards weakly hydrated ions when the interlayer collapse from 18.5 Å to a 15.4 Å hydrate and the increasing temperature. The third stage is characterized by temperatures >60 °C and w/r mass ratios smaller 0.44 g/g. The previous processes are accentuated by higher temperatures and smaller w/r mass ratios but the pore fluid is overprinted by the smectite-illite transition.

Huepers, A.; Kopf, A.

2010-12-01

187

Structural ordering of disordered ligand-binding loops of biotin protein ligase into active conformations as a consequence of dehydration.  

PubMed

Mycobacterium tuberculosis (Mtb), a dreaded pathogen, has a unique cell envelope composed of high fatty acid content that plays a crucial role in its pathogenesis. Acetyl Coenzyme A Carboxylase (ACC), an important enzyme that catalyzes the first reaction of fatty acid biosynthesis, is biotinylated by biotin acetyl-CoA carboxylase ligase (BirA). The ligand-binding loops in all known apo BirAs to date are disordered and attain an ordered structure only after undergoing a conformational change upon ligand-binding. Here, we report that dehydration of Mtb-BirA crystals traps both the apo and active conformations in its asymmetric unit, and for the first time provides structural evidence of such transformation. Recombinant Mtb-BirA was crystallized at room temperature, and diffraction data was collected at 295 K as well as at 120 K. Transfer of crystals to paraffin and paratone-N oil (cryoprotectants) prior to flash-freezing induced lattice shrinkage and enhancement in the resolution of the X-ray diffraction data. Intriguingly, the crystal lattice rearrangement due to shrinkage in the dehydrated Mtb-BirA crystals ensued structural order of otherwise flexible ligand-binding loops L4 and L8 in apo BirA. In addition, crystal dehydration resulted in a shift of approximately 3.5 A in the flexible loop L6, a proline-rich loop unique to Mtb complex as well as around the L11 region. The shift in loop L11 in the C-terminal domain on dehydration emulates the action responsible for the complex formation with its protein ligand biotin carboxyl carrier protein (BCCP) domain of ACCA3. This is contrary to the involvement of loop L14 observed in Pyrococcus horikoshii BirA-BCCP complex. Another interesting feature that emerges from this dehydrated structure is that the two subunits A and B, though related by a noncrystallographic twofold symmetry, assemble into an asymmetric dimer representing the ligand-bound and ligand-free states of the protein, respectively. In-depth analyses of the sequence and the structure also provide answers to the reported lower affinities of Mtb-BirA toward ATP and biotin substrates. This dehydrated crystal structure not only provides key leads to the understanding of the structure/function relationships in the protein in the absence of any ligand-bound structure, but also demonstrates the merit of dehydration of crystals as an inimitable technique to have a glance at proteins in action. PMID:20169168

Gupta, Vibha; Gupta, Rakesh K; Khare, Garima; Salunke, Dinakar M; Surolia, Avadhesha; Tyagi, Anil K

2010-01-01

188

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

189

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

190

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

191

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

192

Geothermal vegetable dehydration at Brady`s Hot Springs, Nevada  

SciTech Connect

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 vegetable dehydration at the plant is described. In July of 1992, the Brady`s Springs geothermal system began being used for power generation by the Brady`s Hot Springs geothermal power plant, operated by Oxbow Power Services, Inc. As a result, the water levels in the food processing plant wells have dropped below usable levels and the geothermal brine is now being supplied by the Oxbow power plant.

Lund, J.W.

1994-07-01

193

Reattachment of dehydrated tooth fragments: two case reports.  

PubMed

Anterior crown fractures are the most common type of injury in dental trauma. The ideal treatment is to reattach the fragments as quickly as possible following intraoral and radiographic examination, but sometimes delayed treatment appointments are necessary because of uninformed patients/parents or multidisciplinary cases included endodontically and periodontically. Delayed reattachment may lead to unesthetic results because of the dehydration of fragments. The purpose of this study was to present 1-year follow-ups of reattachment of dehydrated fragments using dentin bondings and flowable composites in two different cases. The color of the dehydrated fragments was natural in the control appointments and 1-year follow-ups show harmonious integration of color, form and texture after the reattachment of the original piece of tooth. Restoration of the tooth by reattaching the original fragment is the best way of treatment in esthetic, conservative and economic point of view. PMID:25511360

Bozkurt, F O; Demir, B; Erkan, E

2015-01-01

194

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

195

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

196

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

197

Afm Study on Condensation of DNA by Spermidine  

NASA Astrophysics Data System (ADS)

We studied on condensates of a circular and a linear plasmid pUC19 DNA with spermidine in view of reaction time. DNA-spermidine condensates were produced by mixture of 2?l of 5?g/ml DNA solution with 2?l of 0.5mM spermidine aqueous solution. Reaction time is the time elapsed until the mixture is dropped on mica substrate to be imaged with a tapping mode AFM. The reaction times are 30, 15 and 1min. The intermediate progress of DNA-spermidine condensation was found from AFM images dependent on the reaction time.

Katsumata, Shunji; Kigasawa, Harunori; Utsuno, Kuniharu

2001-04-01

198

Secondary condenser Cooling water  

E-print Network

Receiver Secondary condenser LC LC Reboiler TC PC Cooling water PC FCPC Condenser LC XC Throttling valve ¨ mx my l© ª y s § y m «¬ ly my wx l n® ® x np © ¯ Condenser Column Compressor Receiver Super-heater Decanter Secondary condenser Reboiler Throttling valve Expansion valve Cooling water

Skogestad, Sigurd

199

Study of wound dressing structure and hydration/dehydration properties  

NASA Astrophysics Data System (ADS)

Hydrogels manufactured by radio-induced crosslinking and simultaneous sterilisation of hydrogels of PVP, PEG and agar, according to the Rosiak method, have many desirable properties for using as wound dressings. However, some properties need to be improved or better controlled. The membranes need to be strong enough to be freely used. Another important property to be controlled is the capacity of absorption of exudate and the kinetics of drying. Therefore, it was necessary to understand the role of main parameters (agar, PVP, PEG concentration and dose) in the structure of the net and in the hydration and dehydration properties. The structure of the membranes was studied by sol analysis and the hydrating/dehydrating properties were studied by isothermal thermogravimetric analysis. The gel content for all samples were always in agreement with expected values considering that only PVP undergoes crosslinking. The hydrating and dehydration results did not show variation with the tested parameters. It was concluded that the network was solely composed of crosslinked PVP plasticezed by the other compounds. The properties of hydration/dehydration is related rather to diffusion than to capillarity or osmose and to the chemical retention of water in the polymeric matrix.

Lugão, A. B.; Machado, L. D. B.; Miranda, L. F.; Alvarez, M. R.; Rosiak, J. M.

1998-06-01

200

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

201

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...

202

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...

203

Dehydration-Induced Renin Secretion: Involvement of Histaminergic Neurons  

Microsoft Academic Search

Renin secretion is controlled locally in the kidneys as well as via central neuronal mechanisms. The neuronal mechanisms are not fully understood but may involve the neurotransmitter histamine (HA) since centrally infused HA stimulates renin secretion. This, however, does not prove that HA is of any physiological importance for the regulation of renin secretion. Dehydration is a physiological stimulus of

Andreas Kjær; Ulrich Knigge; Henrik Jørgensen; Jørgen Warberg

1998-01-01

204

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

205

POULTRY EXCRETA DEHYDRATION AND UTILIZATION: SYSTEM DEVELOPMENT AND DEMONSTRATION  

EPA Science Inventory

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

206

Diagnosis of pneumonia in children with dehydrating diarrhoea.  

PubMed

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

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

2014-03-01

207

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

208

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

209

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

210

Kinetic, spectroscopic, and theoretical assessment of associative and dissociative methanol dehydration routes in zeolites.  

PubMed

Mechanistic interpretations of rates and in?situ IR spectra combined with density functionals that account for van der Waals interactions of intermediates and transition states within confining voids show that associative routes mediate the formation of dimethyl ether from methanol on zeolitic acids at the temperatures and pressures of practical dehydration catalysis. Methoxy-mediated dissociative routes become prevalent at higher temperatures and lower pressures, because they involve smaller transition states with higher enthalpy, but also higher entropy, than those in associative routes. These enthalpy-entropy trade-offs merely reflect the intervening role of temperature in activation free energies and the prevalence of more complex transition states at low temperatures and high pressures. This work provides a foundation for further inquiry into the contributions of H-bonded methanol and methoxy species in homologation and hydrocarbon synthesis reactions from methanol. PMID:25212869

Jones, Andrew J; Iglesia, Enrique

2014-11-01

211

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

212

The Mechanism of 2-Furaldehyde Formation from d-Xylose Dehydration in the Gas Phase. A Tandem Mass Spectrometric Study  

NASA Astrophysics Data System (ADS)

The mechanism of reactions occurring in solution can be investigated also in the gas phase by suited mass spectrometric techniques, which allow to highlight fundamental mechanistic features independent of the influence of the medium and to clarifying controversial hypotheses proposed in solution studies. In this work, we report a gas-phase study performed by electrospray triple stage quadrupole mass spectrometry (ESI-TSQ/MS) on the dehydration of d-xylose, leading mainly to the formation of 2-furaldehyde (2-FA). It is generally known in carbohydrate chemistry that the thermal acid catalyzed dehydration of pentoses leads to the formation of 2-FA, but several aspects on the solution-phase mechanism are controversial. Here, gaseous reactant ions corresponding to protonated xylose molecules obtained from ESI of a solution containing d-xylose and ammonium acetate as protonating reagent were allowed to undergo collisionally activated decomposition (CAD) into the triple stage quadrupole analyzer. The product ion mass spectra of protonated xylose are characterized by the presence of ionic intermediates arising from xylose dehydration, which were structurally characterized by their fragmentation patterns. As expected, the xylose triple dehydration leads to the formation of the ion at m/z 97, corresponding to protonated 2-FA. On the basis of mass spectrometric evidences, we demonstrated that in the gas phase, the formation of 2-FA involves protonation at the OH group bound to the C1 atom of the sugar, the first ionic intermediate being characterized by a cyclic structure. Finally, energy resolved product ion mass spectra allowed to obtain information on the energetic features of the d-xylose?2-FA conversion.

Ricci, Andreina; Piccolella, Simona; Pepi, Federico; Garzoli, Stefania; Giacomello, Pierluigi

2013-07-01

213

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

214

Microphase Separation in Dehydrated N-isopropylacrylamide/sodium Acrylate Gel  

NASA Astrophysics Data System (ADS)

The first small-angle X-ray scattering (SAXS) measurements were carried out in order to examine the mesoscopic structure in the N-isopropylacrylamide/sodium acrylate (NIPA/SA) gel.By the SAXS measurements, a prominent peak was found in the dehydrated gel around 0.026 Å-1.Taking into account of the cross section magnitude against X-ray,the concentration fluctuation of Na+ ions was a probable candidate for making contrast for the SAXS profile, which depends on the distribution of the hydrophilic group.Therefore, it was concluded that the mesoscopic structure found in the present study is due to the hydrophilic domains in the dehydrated gel which capture the Na+ ions and the remnant water inside the gel.

Sugiyama, Masaaki; Kuwajima, Shuichiro; Soejima, Yuji; Nakamura, Atsushi; Hiramatsu, Nobuyasu; Kikukawa, Takashi; Suzuki, Atsushi; Hara, Kazuhiro

1999-12-01

215

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

216

Electronic nose to study postharvest dehydration of wine grapes  

Microsoft Academic Search

Montepulciano grapes were dehydrated at 10 and 20°C, 45% RH and 1–1.5m\\/s of air flow. Samplings were performed at 10%, 20%, 30%, and 40% of weight loss (wl). TSS (total solids content) increased up to 43° and 36° Brix at 20 and 10°C, respectively, in 27 and 48days. A straight regression line between M (kg water\\/kg dry matter) loss and

Marco Santonico; Andrea Bellincontro; Diana De Santis; Corrado Di Natale; Fabio Mencarelli

2010-01-01

217

Condensed Phase Reaction Dynamics Of Molecular Halogens  

NASA Astrophysics Data System (ADS)

Picosecond transient absorption spectra and kinetics of room temperature iodine solutions following 532 nm or 683 nm excitation are presented. The results indicate that a significant amount of recombination occurs through theA'(3112u) state. Studies at high concentrations show that the A' state is quenched by ground state iodine by way of an I4 or I3 intermediate. The geminate recombination and relaxation of Br2 in CC14 solution is also reported. The similarities and differences of the Br2 and I2 results are interpreted in terms of the respective potential curves.

Abul-Haj, N. A.; Kelley, David F.

1985-04-01

218

Condensation Particle Counter  

E-print Network

Model 3007 Condensation Particle Counter Operation and Service Manual 1930035, Revision C August 2002 P a r t i c l e I n s t r u m e n t s #12;#12;Model 3007 Condensation Particle Counter Operation............................................................................V 1. UNPACKING AND PARTS IDENTIFICATION..................................1 Unpacking the Condensation

Weber, Rodney

219

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

220

Condensation in Microchannels  

Microsoft Academic Search

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

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

2008-01-01

221

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

222

Cryopreservation of Vanda coerulea protocorms by encapsulation-dehydration.  

PubMed

Protocorms of Vanda coerulea were successfully cryopreserved by encapsulation-dehydration in combination with a loading solution. Protocorms were selected 70 days after sowing seeds harvested from 7-month-old fruits. After encapsulation in an alginate matrix composed of 2 percent Na-alginate, 2 M glycerol plus 0.4 M sucrose (loading solution), the protocorms were precultured in modified Vacin and Went (1949) (VW) liquid medium supplemented with 0.7 M sucrose on a shaker (110 rpm) at 25 +/- 3 degree C for 20 h. Encapsulated protocorms were then dehydrated in a sterile air-flow in a laminar air-flow cabinet at 25 +/- 3 degree C for 0-10 h and then directly plunged into liquid nitrogen for 1 d. After thawing at 40 degree C for 2 min, cryopreserved beads were cultured on modified VW agar medium for regrowth. The highest regrowth of 40 percent was observed with cryopreserved beads with 35 percent water content after 8 h dehydration. No morphological variation was detected between non-cryopreserved and cryopreserved plantlets, and ploidy level was unchanged as a result of cryopreservation. PMID:18754065

Jitsopakul, Nipawan; Thammasiri, Kanchit; Ishikawa, Keiko

2008-01-01

223

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

224

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

225

Predicting structures of cross-linked condensation polymers  

NASA Technical Reports Server (NTRS)

Mathematical procedure is used to predict structure of cross-linked condensation polymer differentiated from an additional polymer resulting from specific reaction. Procedure will greatly reduce amount of empirical formulation and testing needed to produce desired product.

Marsh, H. E.

1979-01-01

226

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

227

Acid-catalyzed dehydration of naphthalene-cis-1,2-dihydrodiols: origin of impaired resonance effect of 3-substituents.  

PubMed

Acid-catalyzed dehydrations of substituted naphthalene-cis-1,2-dihydrodiols occur with loss of the 1- or 2-OH group to form 2- and 1-naphthols, respectively. Effects of substituents MeO, Me, H, F, Br, I, and CN at 3-, 6-, and 7-positions of the naphthalene ring are consistent with rate-determining formation of ?-hydroxynaphthalenium ion (carbocation) intermediates. For reaction of the 1-hydroxyl group the 3-substituents are correlated by the Yukawa-Tsuno relationship with ? = -4.7 and r = 0.25 or by ?(p) constants with ? = -4.25; for reaction of the 2-hydroxyl group the 3-substituents are correlated by ?(m) constants with ? = -8.1. The correlations for the 1-hydroxyl imply a surprisingly weak resonance interaction of +M substituents (MeO, Me) with a carbocation reaction center but are consistent with the corresponding correlation for acid-catalyzed dehydration of 3-substituted benzene-cis-1,2-dihydrodiols for which ? = -6.9 and r = 0.43. Substituents at the 6- and 7-positions of the naphthalene rings by contrast are correlated by ?(+) with ? = -3.2 for reaction of the 1-hydroxyl group and ? = -2.7 for reaction of the 2-hydroxyl group. The unimpaired resonance implied by these substituent effects appears to be inconsistent with a previous explanation of the weak resonance of the 3-substituents in terms of imbalance of charge development and/or nonplanarity of the benzenium ring in the transition state. An alternative possibility is that the adjacent hydroxyl group interferes sterically with conjugation of +M substituents. "Hyperaromaticity" of the arenium ion intermediates does not appear to be a factor influencing this behavior. PMID:21992537

Kudavalli, Jaya Satyanarayana; Boyd, Derek R; Sharma, Narain D; More O'Ferrall, Rory A

2011-11-18

228

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

Microsoft Academic Search

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

Harris N. Lazarides; Nicolaos E. Mavroudis

1996-01-01

229

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

230

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

231

Comparative proteomics analysis of differentially expressed proteins in chickpea extracellular matrix during dehydration stress.  

PubMed

Water deficit or dehydration is the most crucial environmental factor that limits crop productivity and influences geographical distribution of many crop plants. It is suggested that dehydration-responsive changes in expression of proteins may lead to cellular adaptation against water deficit conditions. Most of the earlier understanding of dehydration-responsive cellular adaptation has evolved from transcriptome analyses. By contrast, comparative analysis of dehydration-responsive proteins, particularly proteins in the subcellular fraction, is limiting. In plants, cell wall or extracellular matrix (ECM) serves as the repository for most of the components of the cell signaling process and acts as a frontline defense. Thus, we have initiated a proteomics approach to identify dehydration-responsive ECM proteins in a food legume, chickpea. Several commercial chickpea varieties were screened for the status of dehydration tolerance using different physiological and biochemical indexes. Dehydration-responsive temporal changes of ECM proteins in JG-62, a relatively tolerant variety, revealed 186 proteins with variance at a 95% significance level statistically. The comparative proteomics analysis led to the identification of 134 differentially expressed proteins that include predicted and novel dehydration-responsive proteins. This study, for the first time, demonstrates that over a hundred ECM proteins, presumably involved in a variety of cellular functions, viz. cell wall modification, signal transduction, metabolism, and cell defense and rescue, impinge on the molecular mechanism of dehydration tolerance in plants. PMID:17686759

Bhushan, Deepti; Pandey, Aarti; Choudhary, Mani Kant; Datta, Asis; Chakraborty, Subhra; Chakraborty, Niranjan

2007-11-01

232

OSMOTIC AND METABOLIC RESPONSES TO DEHYDRATION AND UREA-LOADING IN A TERRESTRIALLY-HIBERNATING FROG.  

E-print Network

??Physiological responses to dehydration in amphibians are reasonably well documented, although little work has addressed this problem in hibernating animals. We investigated osmotic and metabolic… (more)

Muir, Timothy J

2007-01-01

233

Quark Condensates: Flavour Dependence  

E-print Network

We determine the q-bar q condensate for quark masses from zero up to that of the strange quark within a phenomenologically successful modelling of continuum QCD by solving the quark Schwinger-Dyson equation. The existence of multiple solutions to this equation is the key to an accurate and reliable extraction of this condensate using the operator product expansion. We explain why alternative definitions fail to give the physical condensate.

R. Williams; C. S. Fischer; M. R. Pennington

2007-03-23

234

Vibrational spectroscopic studies in the hydrolysis and condensation of chlorotrimethylsilane.  

PubMed

Raman and infrared spectroscopy were used to study the hydrolysis and condensation of chlorotrimethylsilane (CTMC) in aqueous organic solvents. From the recorded spectra and their intensity variation with time, we were able to identify trimethylsilanol as the reaction intermediate or the hydrolysis product as well as hexamethyldisiloxane (HMDS) as the final condensation product. The measured Raman intensity of CTMS at different time revealed that hydrolysis of CTMS is first order in terms of the CTMS concentration. From the Raman spectra collected under different conditions, it was noted that condensation reaction rates is faster in neutral condition than in acidic condition. PMID:15036105

Li, Ying-Sing; Le, Kim

2004-03-01

235

Vibrational spectroscopic studies in the hydrolysis and condensation of chlorotrimethylsilane  

NASA Astrophysics Data System (ADS)

Raman and infrared spectroscopy were used to study the hydrolysis and condensation of chlorotrimethylsilane (CTMC) in aqueous organic solvents. From the recorded spectra and their intensity variation with time, we were able to identify trimethylsilanol as the reaction intermediate or the hydrolysis product as well as hexamethyldisiloxane (HMDS) as the final condensation product. The measured Raman intensity of CTMS at different time revealed that hydrolysis of CTMS is first order in terms of the CTMS concentration. From the Raman spectra collected under different conditions, it was noted that condensation reaction rates is faster in neutral condition than in acidic condition.

Li, Ying-Sing; Le, Kim

2004-03-01

236

Condensation and large cardinals.  

E-print Network

??Wir definieren lokale Clubmengenkondensation (Local Club Condensation), ein Prinzip, welches Eigenschaften von Gödels Kondensationsprinzip isoliert und verallgemeinert. Wir zeigen, dass wir über einem beliebigen Modell… (more)

Holy, Peter

2010-01-01

237

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

238

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

PubMed

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

Aellig, Christof; Hermans, Ive

2012-09-01

239

Dehydration of isopropanol by pervaporation using aromatic polyetherimide membranes  

SciTech Connect

Aromatic polyetherimide membranes were prepared by the phase inversion method and tested for the pervaporation separation of water from isopropanol with emphasis on the breaking of azcotropic composition and the dehydration of high concentrations of isopropanol. It was found that the membrane selectivity was enhanced by partial evaporation of the solvent in the cast polymer films prior to the gelation step during membrane formation. The membrane performance was shown to be dependent on the feed concentration and the operating temperature. At a feed temperature of 25[degree]C and a permeate pressure of 133 Pa, separation factors of 173 and 384 were achieved for the dehydration of isopropanol solutions at 0.68 (azeotropic composition) and 0.96 mole fractions isopropanol, respectively, with reasonably high permeation rates. The utility of the membranes for the proposed separation was demonstrated; however, these membranes were not prepared under optimized conditions and thus a continuous study is required to rationalize the effects of membrane preparation parameters on membrane performance. 20 refs., 9 figs., 1 tab.

Huang, R.Y.M.; Feng, X. (Univ. of Waterloo, Ontario (Canada))

1993-08-01

240

Enzyme Dehydration Using Microglassification™ Preserves the Protein's Structure and Function.  

PubMed

Controlled enzyme dehydration using a new processing technique of Microglassification™ has been investigated. Aqueous solution microdroplets of lysozyme, ?-chymotrypsin, catalase, and horseradish peroxidase were dehydrated in n-pentanol, n-octanol, n-decanol, triacetin, or butyl lactate, and changes in their structure and function were analyzed upon rehydration. Water solubility and microdroplet dissolution rate in each solvent decreased in the order: butyl lactate > n-pentanol > triacetin > n-octanol > n-decanol. Enzymes Microglassified™ in n-pentanol retained higher activity (93%-98%) than n-octanol (78%-85%) or n-decanol (75%-89%), whereas those Microglassified™ in triacetin (36%-75%) and butyl lactate (48%-79%) retained markedly lower activity. FTIR spectroscopy analyses showed ?-helix to ?-sheet transformation for all enzymes upon Microglassification™, reflecting a loss of bound water in the dried state; however, the enzymes reverted to native-like conformation upon rehydration. Accelerated stressed-storage tests using Microglassified™ lysozyme showed a significant (p < 0.01) decrease in enzymatic activity from 46,560 ± 2736 to 31,060 ± 4327 units/mg after 3 months of incubation; however, it was comparable to the activity of the lyophilized formulation throughout the test period. These results establish Microglassification™ as a viable technique for enzyme preservation without affecting its structure or function. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:640-651, 2015. PMID:25557848

Aniket; Gaul, David A; Bitterfield, Deborah L; Su, Jonathan T; Li, Victoria M; Singh, Ishita; Morton, Jackson; Needham, David

2015-02-01

241

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

242

Hydrated Salts: Dehydration, Dissolution, and Incongruent Melting In Terrestrial Evaporites and at Meridiani Planum, Mars  

NASA Astrophysics Data System (ADS)

The Opportunity rover and orbital observations of Meridiani Planum (Mars) have revealed much about the region's stratigraphy, chemistry, sedimentology, and mineralogy of what appears to be a layered lacustrine sedimentary sequence, including chemical sediments deposited by evaporative or freezing processes in a large, saline lake or sea. The roles of evaporation versus freezing are not clearly elucidated in the data, but both freezing and evaporation are likely on Mars for any paleoclimate scenario that minimizes excursions from current climate. The rock sequences reveal many interesting features reported in press accounts, NASA press releases, and in conference presentations by the MER science teams. The topic dealt with here concerns indirect sedimentologic indications of phase changes that seem to have generated negative volume changes due to dehydration, dissolution, and/or annealing. These indicators include microkarstic and polygonal structures in the laminated chemical sediments. These processes have operated on a small scale at Meridiani Planum, and serve as possible analogs for processes operative on mega scales elsewhere on Mars. Comparable processes are common in terrestrial evaporite basins and in sequences of evaporitic rocks. Fluctuations of mineral water content drive large changes in volume and pore fluid pressure, and these exert stresses that can drive extensional fracturing and faulting, folding, thrusting, and diapirism. These processes may be even more important on Mars than on Earth, because on Mars solid salts may be more abundant, more widespread, and subject to larger ranges of hydration states; the effects of these processes may be better preserved for lack of erasure by fluvial erosional processes and other degradational processes on Earth's more active surface. Specific processes and reactions proposed here can account for the sedimentologic structures observed at Meridiani Planum based on aqueous chemical phase equilibria and phase-volume data applied to the mineralogies and chemistries observed or inferred from spacecraft data. Dehydration and/or open-system incongruent dissolution of Mg-Fe-Ca-sulfate hydrates can explain both the microkarstic and decimeter-scale polygonal structures observed by the Opportunity rover. Close analogs of these inferred processes and observed features are common in terrestrial evaporite sequences. Considering scenarios for minimized excursions from current climate, we attribute the structures either to dehydration or dissolution etching by cryogenic acid brines-- or both operating in tandem or in sequence. These processes operating at low rates may remain active even as Opportunity observes the layered/laminated rock sequence. Inclusion on future spacecraft of simple soil pH measurements would do much to resolve questions of possible present-day activity of acidic brine films. Because many salt dehydration steps occur at temperatures far below the melting point of ice, future differential scanning calorimetry/thermal analysis must consider very small increments of heating in the 200-400 K temperature range if we are to understand adequately the composition and hydration states of Martian salts.

Kargel, J. S.; Dougherty, A.; Feldman, W.; Hogenboom, D.; Marion, G.; McCarthy, C.; Prieto-Ballesteros, O.

2004-12-01

243

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

244

Witness of fluid-flow organization during high-pressure antigorite dehydration  

NASA Astrophysics Data System (ADS)

The link between devolatilization reactions and fluid flow is crucial to unravel important geodynamic processes in subduction zones as deformation and element transfer is extremely controlled by the presence of water. At high confining pressure, significant fluid pressure gradients are expected in a reacting rock being dehydrated, because of its rather limited permeability [1]. Compactation-driven fluid flow seems to be an intrinsic mechanism occurring at devolatilization of viscolastic rocks. Nevertheless, and despite the important implications of this coupled deformation/fluid-migration mechanism for fluid transport, a conclusive confirmation of these processes by petrological and textural evidences in metamorphic terrains has been hampered by the scarcity of devolatilization fronts in the geological record. Evidences of high-pressure antigorite dehydration found at Cerro del Almirez (Betic Cordillera, Spain) [2] represent a noteworthy exception. Here, the transition between the hydrous protolith (antigorite serpentinite) and the prograde product assemblage (olivine + orthopyroxene + chlorite, chlorite harzburgite) is extremely well preserved and can be surveyed in detail. The maximum stability of the antigorite has been experimentally determined at ~680°C at 1.6-1.9 GPa [3]. Antigorite dehydration is accompanied by release of high amounts of high-pressure water-rich fluids (~ 9 wt.% fluid). Distinctive layers (up to 1 m thick) of transitional lithologies occur in between atg-serpentinite and chl-harburgite all along the devolatilization front, consisting of (1) chlorite-antigorite olivine-serpentinite, which gradually changes to (2) chlorite-antigorite-olivine-orthopyroxene serpentinite. These transitional lithologies are more massive and darker in color than atg-serpentinite and largely consist of coarse sized grains of antigorite and chlorite (250-500 ?m). Antigorite in these assemblages is characterized by microstructural disorder features, which are lacking in antigorite far from the devolatilization front [4]. The sharp appearance of chlorite (Chl-in), crosscutting the serpentinite foliation, and coarsening of olivine define the upper limit of the transitional lithologies, whereas the lower limit (Atg-out) is gradational to chl-harzburgite. The modal increase of orthopyroxene is concomitant with the gradual disappearance of antigorite. The gradual disappearance of antigorite over short distances leads to the final prograde assemblage in the Chl-harzburgite with two contrasting textures: (1) coarse granular texture and (2) an intriguing spinifex-like texture (arborescent growth of centimeter-sized olivine and orthopyroxene). Both textures alternate at the meter to tens of meters scale over the entire massif. We interpret these textures as the result of contrasting pore fluid overpressure, reaction rates and fluid-flow organization shortly after the antigorite breakdown. These observations will be discussed on the frame of the reaction kinetic and the propagation of deformation associated to fluid pressure gradients. [1] Connolly, Journal of Geophysical Research 112 (B8), 18 (1997). [2] Trommsdorff, López Sánchez-Vizcaíno, Gómez-Pugnaire et al., Contrib Mineral Petr 132 (2), 139 (1998). [3] Padrón-Navarta, Hermann, Garrido et al., Contrib Mineral Petr 159 (1), 25 (2010). [4] Padrón-Navarta, López Sánchez-Vizcaíno, Garrido et al., Contrib Mineral Petr 156 (5), 679 (2008).

López Sánchez-Vizcaíno, Vicente; Padrón-Navarta, José Alberto; Garrido, Carlos J.; Gómez-Pugnaire, María. Teresa

2010-05-01

245

Condensation Energy of a Spacetime Condensate  

E-print Network

Starting from an analogy between the Planck-Einstein scale and the dual length scales in Ginzburg-Landau theory of superconductivity, and assuming that space-time is a condensate of neutral fermionic particles with Planck mass, we derive the baryonic mass of the universe. In that theoretical framework baryonic matter appears to be associated with the condensation energy gained by spacetime in the transition from its normal (symetric) to its (less symetric) superconducting-like phase. It is shown however that the critical transition temperature cannot be the Planck temperature. Thus leaving open the enigma of the microscopic description of spacetime at quantum level.

Clovis Jacinto de Matos; Pavol Valko

2010-12-17

246

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

247

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

248

Safety of chlorination reactions  

Microsoft Academic Search

Chlorination reactions are part of various processes in the chemical industry, to manufacture heavy chemicals, specialty chemicals, pesticides and pharmaceuticals, in inorganic and organic chemistry. They are a valuable tool in organic synthesis.The hazard of processing chlorine involves:u- Gas phase explosion;- Runaway reaction or thermal explosion in the condensed phase.Gas phase explosion hazard with chlorine as an oxidizer is present

Jean-Louis Gustin; Alexandre Fines

1996-01-01

249

Base-catalyzed dehydration of 3-substituted benzene cis-1,2-dihydrodiols: stabilization of a cyclohexadienide anion intermediate by negative aromatic hyperconjugation.  

PubMed

Evidence that a 1,2-dihydroxycyclohexadienide anion is stabilized by aromatic "negative hyperconjugation" is described. It complements an earlier inference of "positive" hyperconjugative aromaticity for the cyclohexadienyl cation. The anion is a reactive intermediate in the dehydration of benzene cis-1,2-dihydrodiol to phenol. Rate constants for 3-substituted benzene cis-dihydrodiols are correlated by ?(-) values with ? = 3.2. Solvent isotope effects for the reactions are k(H(2)O)/k(D(2)O) = 1.2-1.8. These measurements are consistent with reaction via a carbanion intermediate or a concerted reaction with a "carbanion-like" transition state. These and other experimental results confirm that the reaction proceeds by a stepwise mechanism, with a change in rate-determining step from proton transfer to the loss of hydroxide ion from the intermediate. Hydrogen isotope exchange accompanying dehydration of the parent benzene cis-1,2-dihydrodiol was not found, and thus, the proton transfer step is subject to internal return. A rate constant of ~10(11) s(-1), corresponding to rotational relaxation of the aqueous solvent, is assigned to loss of hydroxide ion from the intermediate. The rate constant for internal return therefore falls in the range 10(11)-10(12) s(-1). From these limiting values and the measured rate constant for hydroxide-catalyzed dehydration, a pK(a) of 30.8 ± 0.5 was determined for formation of the anion. Although loss of hydroxide ion is hugely exothermic, a concerted reaction is not enforced by the instability of the intermediate. Stabilization by negative hyperconjugation is proposed for 1,2-dihydroxycyclohexadienide and similar anions, and this proposal is supported by additional experimental evidence and by computational results, including evidence for a diatropic ("aromatic") ring current in 3,3-difluorocyclohexadienyl anion. PMID:22830996

Kudavalli, Jaya Satyanarayana; Rao, S Nagaraja; Bean, David E; Sharma, Narain D; Boyd, Derek R; Fowler, Patrick W; Gronert, Scott; Kamerlin, Shina Caroline Lynn; Keeffe, James R; More O'Ferrall, Rory A

2012-08-29

250

Research on the use of dehydrated whole maize plant in the feed of growing rabbits  

E-print Network

Research on the use of dehydrated whole maize plant in the feed of growing rabbits Maria at the wax stage were given to growing rabbits. A rearing trial was carried out in 52 rabbits weaned at 28 during the trial, but significantly until 60 days of age. Utilization of dehydrated whole maize plant

Paris-Sud XI, Université de

251

Dehydration does not affect the radial pressures produced by the earthworm Aporrectodea caliginosa  

Microsoft Academic Search

As a soil dries, the earthworms in that soil dehydrate and become less active. Moisture stress may weaken an earthworm, lowering the radial pressure that the animal can produce. This possibility was investigated for the earthworm Aporrectodea caliginosa (Savigny). Pressures were compared for saturated earthworms (worms taken from saturated soil) and stressed earthworms (worms that had been partially dehydrated by

Robert J. Stovold; W. Richard Whalley; Peter J. Harris

2003-01-01

252

40 CFR 63.765 - Glycol dehydration unit process vent standards.  

Code of Federal Regulations, 2012 CFR

...safety devices that vent directly to the atmosphere may be used on the air emission control...that the total HAP emissions to the atmosphere from the glycol dehydration unit process...satisfaction, that total emissions to the atmosphere from the glycol dehydration unit...

2012-07-01

253

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

Microsoft Academic Search

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

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

1992-01-01

254

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

E-print Network

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

Barthelat, Francois

255

Waste grape skins thermal dehydration: potential release of colour, phenolic and aroma compounds into wine  

Microsoft Academic Search

Exploitation of grape waste material is scarce. One of the main issues to deal with is its high moisture content, as it causes spoilage and degradation of valuable compounds. In order to assess this limitation, four different Vitis vinifera waste grape skins from the juice industry were dehydrated at 60, 90 and 100°C. Characterisation of dehydrated waste grape skins (DWGS)

Miguel A. Pedroza; Manuel Carmona; Francisco Pardo; M. Rosario Salinas; Amaya Zalacain

2012-01-01

256

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...

257

Effect of hydration–dehydration cycles on germination of seven Calligonum species  

Microsoft Academic Search

A greenhouse experiments were conducted to study the effects of imbibition phase and hydration–dehydration cycles on the germination of seven Calligonum species, dominant shrubs in mobile sand dunes and stabilized sand field in the northern desert of China. In August 1998, seeds of Calligonum were collected and were treated by different hydration–dehydration cycles. The results show that there is not

Jun Ren; Ling Tao

2003-01-01

258

Soybean genotypic differences in sensitivity of symbiotic nitrogen fixation to soil dehydration  

Microsoft Academic Search

Nitrogen fixation activity by soybean (Glycine max (L.) Merr.) nodules has been shown to be especially sensitive to soil dehydration. Specifically, nitrogen fixation rates have been found to decrease in response to soil dehydration preceding alterations in plant gas exchange rates. The objective of this research was to investigate possible genetic variation in the sensitivity of soybean cultivars for nitrogen

Keba Sall; T. R. Sinclair

1991-01-01

259

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

260

Freeze-Tolerant Condensers  

NASA Technical Reports Server (NTRS)

Two condensers designed for use in dissipating heat carried by working fluids feature two-phase, self-adjusting configurations such that their working lengths automatically vary to suit their input power levels and/or heat-sink temperatures. A key advantage of these condensers is that they can function even if the temperatures of their heat sinks fall below the freezing temperatures of their working fluids and the fluids freeze. The condensers can even be restarted from the frozen condition. The top part of the figure depicts the layout of the first condenser. A two-phase (liquid and vapor) condenser/vapor tube is thermally connected to a heat sink typically, a radiatively or convectively cooled metal panel. A single-phase (liquid) condensate-return tube (return artery) is also thermally connected to the heat sink. At intervals along their lengths, the condenser/vapor tube and the return artery are interconnected through porous plugs. This condenser configuration affords tolerance of freezing, variable effective thermal conductance (such that the return temperature remains nearly constant, independently of the ultimate sink temperature), and overall pressure drop smaller than it would be without the porous interconnections. An additional benefit of this configuration is that the condenser can be made to recover from the completely frozen condition either without using heaters, or else with the help of heaters much smaller than would otherwise be needed. The second condenser affords the same advantages and is based on a similar principle, but it has a different configuration that affords improved flow of working fluid, simplified construction, reduced weight, and faster recovery from a frozen condition.

Crowley, Christopher J.; Elkouhk, Nabil

2004-01-01

261

Chemistry at and near the surface of liquid sulfuric acid: A kinetic, thermodynamic, and mechanistic analysis of heterogeneous reactions of acetone  

SciTech Connect

The interactions of gas-phase acetone with liquid sulfuric acid solutions are described. The solutions were prepared as 0.05--0.10 {micro}m thick films deposited on single-crystal metal substrates. Experiments were carried out over broad ranges of acid composition (70 {minus} >96 wt % H{sub 2}SO{sub 4}), temperature (180--220 K), and acetone pressure (10{sup {minus}7}{minus}10{sup {minus}3} Pa). Two types of measurements are reported: the time-dependent acetone uptake probability, and the infrared spectra of absorbed acetone and its reaction products. From the infrared measurements, a reaction scheme is identified in which gas-phase acetone is taken up by sulfuric acid to form protonated acetone. In solutions containing more than 70 wt % H{sub 2}SO{sub 4}, protonated acetone undergoes a self-condensation/dehydration reaction to form mesityl oxide. In films that contain 85 wt % or more H{sub 2}SO{sub 4}, a second reaction sequence occurs, ultimately resulting in the formation of tremethylbenzene. The uptake probability measurements are consistent with the infrared data. In 70 wt % H{sub 2}SO{sub 4}, the acetone uptake probability rapidly decreases from an initial value near unity to a steady-state value of zero, due to the formation of a saturated acetone + sulfuric acid solution. The Henry`s law solubility constants of acetone in 70 wt % H{sub 2}SO{sub 4} were obtained from the integrated uptake measurements. The temperature dependence of the measurements implies that the standard-state enthalpy and entropy changes of acetone solution in 70 wt % sulfuric acid are {minus}66 kJ mol{sup {minus}1} and {minus}249 J mol{sup {minus}1} K{sup {minus}1}, respectively. In the more concentrated films, the steady-state uptake probability is never measured to be zero, since absorbed acetone goes on to form the condensation/dehydration products. A two-step kinetic scheme is proposed to account for the reactions of acetone in sulfuric acid. By fitting the data to the model predictions, the Henry`s law solubility constants and the reaction rate constants may be estimated.

Duncan, J.L.; Schindler, L.R.; Roberts, J.T. [Univ. of Minnesota, MN (United States). Dept. of Chemistry] [Univ. of Minnesota, MN (United States). Dept. of Chemistry

1999-08-26

262

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

263

Pyropia yezoensis can utilize CO2 in the air during moderate dehydration  

NASA Astrophysics Data System (ADS)

Pyropia yezoensis, an intertidal seaweed, experiences regular dehydration and rehydration with the tides. In this study, the responses of P. yezoensis to dehydration and rehydration under high and low CO2 concentrations ((600-700)×10-6 and (40-80)×10-6, named Group I and Group II respectively) were investigated. The thalli of Group I had a significantly higher effective photosystem II quantum yield than the thalli of Group II at 71% absolute water content (AWC). There was little difference between thalli morphology, total Rubisco activity and total protein content at 100% and 71% AWC, which might be the basis for the normal performance of photosynthesis during moderate dehydration. A higher effective photosystem I quantum yield was observed in the thalli subjected to a low CO2 concentration during moderate dehydration, which might be caused by the enhancement of cyclic electron flow. These results suggested that P. yezoensis can directly utilize CO2 in ambient air during moderate dehydration.

Zhou, Wei; He, Linwen; Yang, Fang; Lin, Apeng; Zhang, Baoyu; Niu, Jianfeng; Wang, Guangce

2014-03-01

264

Spectroscopic investigation of the thermal conversion of catalytically dehydrated polyvinyl alcohol  

SciTech Connect

The authors examine the structural conversion of dehydrated polyvinyl alcohol thermally treated at temperatures exceeding the temperature of the catalytic dehydration. The authors used electron and infrared spectroscopy to study the thermal conversion of catalytically dehydrated polyvinyl alcohol in an inert atmosphere and in air. Aluminum chloride and hydrogen chloride were used as catalysts of the dehydration. Spectra are shown which were obtained in the visible part from ALCL/sub 3/-containing polyvinyl alcohol films after their thermal treatment in an inert gas flow. It is shown that optimal temperatures must be selected to obtain high-quality recordings of optical information when the dehydration of polyvinyl alcohol is to be used to advantage.

Gavrilov, M.Z.

1986-09-01

265

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

Microsoft Academic Search

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

J. Leonieni; L. Rechardt

1972-01-01

266

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

267

Hypernatraemic dehydration and breast feeding: a population study  

PubMed Central

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

Oddie, S; Richmond, S; Coulthard, M

2001-01-01

268

Outcomes related to dehydration in the pediatric population.  

PubMed

The purpose of this pilot study was twofold: 1) to determine whether there was a statistically significant difference in nursing-sensitive patient outcome ratings from admission to discharge, and 2) to describe nursing interventions used to care for children admitted with a primary diagnosis of dehydration to a 272-bed Midwestern community hospital. Twenty-nine patient care records meeting study criteria were extracted from all pediatric admission records during the study period. The patient care records are part of a computerized clinical documentation system using the standardized nursing languages of the North American Nursing Diagnosis Association, the Nursing Interventions Classification, and the Nursing Outcomes Classification (NOC). A statistically significant improvement in outcome ratings from admission to discharge was demonstrated for seven of eight NOC outcomes. PMID:17889729

Scherb, Cindy A; Stevens, Marcia S; Busman, Carol

2007-10-01

269

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

270

Effect of Dehydration Prior to Cryopreservation of Large Equine Embryos  

PubMed Central

Cryopreservation of equine embryos > 300 ?m in diameter results in low survival rates using protocols that work well for smaller equine embryos. These experiments tested the potential benefit of incorporating a dehydration step prior to standard cryopreservation procedures. Forty-six, d 7–8, grade 1, equine embryos ? 400 ?m in diameter were subjected to one of the following treatments: (A) 2-min in 0.6 M galactose, 10 min in 1.5 M glycerol, slow freeze (n=21); (B) 10 min in 1.5 M glycerol, slow freeze (n=15); (C) 2 min in 0.6 M galactose, 10 min in 1.5 M glycerol, followed by exposure to thaw solutions, then culture medium (n=5); (D) transferred directly to culture medium (n=5). Frozen embryos were thawed and subjected to a 3-step cryoprotectant removal. Five embryos from each treatment were evaluated morphologically after 24 and 48 h culture (1=excellent, 5=degenerate/dead). All treatments had at least 4/5 embryos with a quality score ? 3 at these time points except treatment B (2/5 at 24 h, 1/5 at 48 h). Subsequent embryos from treatment A (n=16) or B (n=10) were matched in sets of two for size and treatment, thawed, and immediately transferred in pairs to 13 recipients. Only two recipient mares were pregnant; one received two 400 ?m embryos from treatment A, and the other one 400 ?m and one 415 ?m embryo from treatment B. There was no advantage of incorporating a 2 min dehydration step into the cryopreservation protocol for large equine embryos. PMID:19375416

Barfield, JP; McCue, PM; Squires, EL; Seidel, GE

2009-01-01

271

Advancing Microwave Technology for Dehydration Processing of Biologics  

PubMed Central

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

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

2013-01-01

272

Spring dehydration in the Antarctic stratospheric vortex observed by HALOE  

NASA Technical Reports Server (NTRS)

The distribution of dehydrated air in the middle and lower stratosphere during the 1992 Southern Hemisphere spring is investigated using Halogen Occultation Experiment (HALOE) observations and trajectory techniques. Comparisons between previously published Version 9 and the improved Version 16 retrievals on the 700-K isentropic surface show very slight (0.05 ppmv) increases in Version 16 CH4 relative to Version 9 within the polar vortex. Version 16 H2O mixing ratios show a reduction of 0.5 ppmv relative to Version 9 within the polar night jet and a reduction of nearly 1.0 ppmv in middle latitudes when compared to Version 9. The version 16 HALOE retrievals show low mixing ratios of total hydrogen (2CH4 + H2O) within the polar vortex on both 700 and 425 K isentropic surfaces relative to typical middle-stratospheric 2CH4 + H2O mixing ratios. The low 2CH4 + H2O mixing ratios are associated with dehydration. Slight reductions in total hydrogen, relative to typical middle-stratospheric values, are found at these levels throughout the Southern Hemisphere during this period. Trajectory calculations show that middle-latitude air masses are composed of a mixture of air from within the polar night jet and air from middle latitudes. A strong kinematic barrier to large-scale exchange is found on the poleward flank of the polar night jet at 700 K. A much weaker kinematic barrier is found at 425 K. The impact of the finite tangent pathlength of the HALOE measurements is investigated using an idealized tracer distribution. This experiment suggests that HALOE should be able to resolve the kinematic barrier, if it exists.

Pierce, R. Bradley; Grose, William L.; Russell, James M., III; Tuck, Adrian F.; Swinbank, Richard; O'Neill, Alan

1994-01-01

273

Condensation of aluminosilicate gels—model system for geopolymer binders  

Microsoft Academic Search

The reaction of geopolymer binders can be subdivided into two more or less parallel reactions, (1) the dissolution of reactable silicate and aluminate monomers from the reactive solid material and (2) the condensation to an aluminosilicate gel. Due to the wide range of possible raw materials, the question arises whether the Si\\/Al ratio of the hardened aluminosilicate network is predominated

A. Buchwald; H.-D. Zellmann; Ch. Kaps

2011-01-01

274

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

275

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

276

Proper Design Saves Energy for Molecular Sieve Dehydration Systems  

E-print Network

Industrial Energy Technology Conference Volume II, Houston, TX, April 15-18, 1984 slipstream is heated, then used to heat the sieve bed. From the bed, the gas is cooled and water is condensed at the regeneration gas scrubber. From the regeneration...

Barrow, J. A.; Veldman, R.

1984-01-01

277

Key condenser failure mechanisms  

SciTech Connect

Eight practical lessons highlight many of the factors that can influence condenser tube corrosion at coal-fired utilities and the effects contaminant in-leakage can have on steam generating units. 1 ref., 4 figs.

Buecker, B.

2009-04-15

278

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

279

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

280

Poly-benzylic ammonium chloride resins as solid catalysts for fructose dehydration.  

PubMed

5-hydroxymethylfurfural (HMF) is one of the most promising platform molecules, and can be converted into a variety of interesting chemicals. The production of HMF is essentially targeted at bulk chemicals downstream, such as chemicals for the fuels and plastics industries. One critical challenge in HMF production processes is the link to further value-adding reactions in a simple and efficient way (e.g., fewer isolation and purification steps). Herein, a novel poly-benzyl ammonium chloride (PBnNH3 Cl) resin is developed as a highly efficient and stable catalyst for dehydration of carbohydrates into HMF. In the isopropanol system, PBnNH3 Cl produces high purity HMF that is suitable as feedstock for oxidation to 2,5-furandicarboxylic acid (FDCA). The excellent catalytic properties together with its easy synthesis, low cost, and nontoxic nature make this poly-ammonium resin a promising catalyst for the development of new and efficient processes for biomass-based chemicals. PMID:24903397

Teong, Siew Ping; Yi, Guangshun; Cao, Xueqin; Zhang, Yugen

2014-08-01

281

Catalytic dehydration of fructose to 5-hydroxymethylfurfural over Nb2O5 catalyst in organic solvent.  

PubMed

The catalytic dehydration of fructose to 5-hydroxymethylfurfural (HMF) in DMSO was performed over Nb2O5 derived from calcination of niobic acid at various temperatures (300-700 °C). The catalysts were characterized by powder X-ray diffraction, N2 physical adsorption, temperature-programed desorption of NH3, n-butylamine titration using Hammett indicators, infrared spectroscopy of adsorbed pyridine, and X-ray photoelectron spectroscopy. It was found that both catalytic activity and surface acid sites decrease with increasing calcination temperatures. The Nb2O5 derived from calcination of niobic acid at 400 °C reveals the maximum yield of HMF among all the catalysts, although the amount of acid sites on the catalyst is lower than that on the sample calcined at 300 °C. The results suggest that the presence of larger amounts of strong acid sites on the surface of the Nb2O5 calcined at 300 °C may promote side reactions. The Nb2O5 prepared at 400 °C shows 100% fructose conversion with 86.2% HMF yield in DMSO at 120 °C after 2 h. The activity of the catalyst decreases gradually during recycle because of coke deposition; however, it can be fully recovered by calcination at 400 °C for 2 h, suggesting that this catalyst is of significance for practical applications. PMID:23348242

Wang, Fenfen; Wu, Hai-Zhen; Liu, Chun-Ling; Yang, Rong-Zhen; Dong, Wen-Sheng

2013-03-01

282

Acid-catalyzed dehydration of fructose into 5-hydroxymethylfurfural by cellulose-derived amorphous carbon.  

PubMed

Carbonaceous solid (CS) catalysts with --SO?H, --COOH, and phenolic --OH groups were prepared by incomplete hydrothermal carbonization of cellulose followed by either sulfonation with H?SO? to give carbonaceous sulfonated solid (CSS) material or by both chemical activation with KOH and sulfonation to give activated carbonaceous sulfonated solid (a-CSS) material. The obtained carbon products (CS, CSS, and a-CSS) were amorphous; the CSS material had a small surface area (<0.5?m² g?¹) and a high --SO?H group concentration (0.953?mmol?g?¹), whereas the a-CSS material had a large surface area (514?m² ?g ?¹) and a low --SO?H group concentration (0.172?mmol?g?¹). The prepared materials were evaluated as catalysts for the dehydration of fructose to 5-hydroxymethylfurfural (5-HMF) in the ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]). Remarkably high 5-HMF yields (83?%) could be obtained efficiently (80?°C and 10?min reaction time). CSS and a-CSS catalysts had similar catalytic activities and efficiencies for the conversion of fructose to 5-HMF in [BMIM][Cl]; this could be explained by the trade-off between --SO?H group concentration (high for CSS) and surface area (high for a-CSS). The cellulose-derived catalysts and ionic liquid exhibited constant activity for five successive recycles, and thus, the methods developed provide a renewable strategy for biomass conversion. PMID:22927099

Qi, Xinhua; Guo, Haixin; Li, Luyang; Smith, Richard L

2012-11-01

283

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

284

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

285

Comparative nephrotoxicity of carboplatin and cisplatin in euvolemic and dehydrated rats.  

PubMed

The aim of this study was to compare the renal tolerance of cisplatin and carboplatin in euvolemic and dehydrated rats. A total of 79 euvolemic or dehydrated male rats were randomly assigned to receive cisplatin (5 mg/kg body weight, i.p.), carboplatin (40 mg/kg body weight, i.p.) or vehicle. Body weight, serum creatinine, creatinine clearance, fractional excretion of sodium and urinary NAG excretion were recorded on days 1 and 5. Glomerular filtration rate (GFR), effective renal plasma flow (ERPF) and renal histology were determined on day 5. In the euvolemic and dehydrated control and carboplatin groups we observed no change in serum electrolytes, serum creatinine, creatinine clearance, GFR and ERPF. In the euvolemic and dehydrated control groups we observed no change in urinary NAG excretion. Carboplatin induced a slight but significant increase in urinary NAG excretion. In dehydrated rats carboplatin induced a significantly higher increase in urinary NAG excretion than in euvolemic rats. Cisplatin induced a marked and significant decrease in GFR and ERPF, and a significant increase in NAG. Dehydration markedly potentiated cisplatin nephrotoxicity. Euvolemic rats treated with cisplatin exhibited slight renal lesions with a mean score which was similar to the control group. The most extensive lesions were observed in euvolemic and dehydrated cisplatin treated rats with tubular necrosis in the outer stripe of the medulla.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8457719

Martinez, F; Deray, G; Dubois, M; Beaufils, H; Jacquiaud, C; Bourbouze, R; Benhmida, M; Jaudon, M C; Jacobs, C

1993-02-01

286

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

287

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

PubMed

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

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

2012-11-01

288

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

289

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

290

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

PubMed Central

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

2014-01-01

291

Different effects of light irradiation on the photosynthetic electron transport chain during apple tree leaf dehydration.  

PubMed

Effects of light irradiation on the photosynthetic electron transport chain between P680 and P700 in apple tree leaves was probed with chlorophyll a fluorescence transient and 820 nm transmission measurements during dehydration under different light intensities. The results showed that light accelerated the leaf water-loss rate during dehydration. Leaf dehydration lowered the maximum quantum yield of PSII and the far-red light induced maximal transmission change at 820 nm, but increased the relative variable fluorescence intensity at J-step, especially under increasing irradiation conditions. During leaf dehydration, irradiation lowered the relative variable fluorescence intensity at I-step. At the beginning of leaf dehydration, moderate light accelerated the leaf water-loss rate and then lowered the maximal light-trapping efficiency of P???. Upon further dehydration under moderate light or dehydration under high light, light accelerated the water-loss rate and also directly decreased the maximal light-trapping efficiency of P680. The more significant decrease in the exchange capacity of plastoquinones at the Q(B) site was mainly attributed to the faster water-loss rate under moderate light than in the dark. Under high light, irradiation also directly lowered the capacity. The reoxidation of PQH? in the dehydrated leaves was enhanced by the light irradiation. The rapidly decreased contents of P700 + plastocyanin were mainly attributed to the faster water-loss rate under light conditions in contrast with that in the dark. The different effects of light irradiations on the photosynthetic electron transport chain might be involved in the acclimation of apple tree leaves to dehydration. PMID:22484842

Li, Pengmin; Ma, Fengwang

2012-06-01

292

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

NASA Astrophysics Data System (ADS)

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

Massonne, H.; Willner, A. P.

2007-12-01

293

Concomitant dehydration mechanisms in single crystals of alpha,alpha-trehalose.  

PubMed

The dehydration behaviour of alpha,alpha-trehalose (alpha-D-glucopyranosyl alpha-D-glucopyranoside) dihydrate single crystals is investigated by thermomicroscopy, Raman microscopy, and differential scanning calorimetry. The results show at a given stage the simultaneous presence of two polymorphic forms, amorphous material, and movement of a fluid phase. The study also underlines that the characterization of the average phase by conventional XRPD and DSC techniques is not sufficient to describe the dehydration mechanisms of alpha,alpha-trehalose particles. Moreover, it confirms that the dehydration behaviour is mainly driven by heterogeneities and the rate of water loss. PMID:19875105

Dupray, Valérie; Berton, Benjamin; Ossart, Stephen; Atmani, Hassan; Petit, Marie-Noëlle; Coquerel, Gérard

2009-12-14

294

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

295

Condensed Genome Structure  

PubMed Central

Large, tailed dsDNA-containing bacteriophage genomes are packaged to a conserved and high density (~500 mg/ml), generally in ~2.5-nm, duplex-to-duplex, spaced, organized DNA shells within icosahedral capsids. Phages with these condensate properties, however, differ markedly in their inner capsid structures: (1) those with a naked condensed DNA, (2) those with many dispersed unstructured proteins embedded within the DNA, (3) those with a small number of localized proteins, and (4) those with a reduced or DNA-free internal protein structure of substantial volume. The DNA is translocated and condensed by a high-force ATPase motor into a procapsid already containing the proteins that are to be ejected together with the DNA into the infected host. The condensed genome structure of a single-phage type is unlikely to be precisely determined and can change without loss of function to fit an altered capsid size or internal structure. Although no such single-phage condensed genome structure is known exactly, it is known that a single general structure is unlikely to apply to all such phages. PMID:22297527

Black, Lindsay W.

2013-01-01

296

Condensed Matter Field Theory  

NASA Astrophysics Data System (ADS)

Over the past few decades, in concert with ground-breaking experimental advances, condensed matter theory has drawn increasingly from the language of low-energy quantum field theory. This primer is aimed at elevating graduate students of condensed matter theory to a level where they can engage in independent research. It emphasizes the development of modern methods of classical and quantum field theory with applications oriented around condensed matter physics. Topics covered include second quantization, path and functional field integration, mean-field theory and collective phenomena, the renormalization group, and topology. Conceptual aspects and formal methodology are emphasized, but the discussion is rooted firmly in practical experimental application. As well as routine exercises, the text includes extended and challenging problems, with fully worked solutions, designed to provide a bridge between formal manipulations and research-oriented thinking. This book will complement graduate level courses on theoretical quantum condensed matter physics. Spans the field of modern condensed matter theory focusing on field theory techniques Written to facilitate learning, with numerous challenging exercises, with fully worked solutions, aimed at physicists starting graduate-level courses The theoretical methods are firmly set in concrete experimental applications

Altland, Alexander; Simons, Ben

2006-06-01

297

Dehydration of ethanol by facile synthesized glucose-based silica.  

PubMed

Bioethanol is considered a potential liquid fuel that can be produced from biomass by fermentation and distillation. Although most of the water is removed by distillation, the purity of ethanol is limited to 95-96 % due to the formation of a low-boiling point, water-ethanol azeotrope. To improve the use of ethanol as a fuel, many methods, such as dehydration, have been proposed to avoid distillation and improve the energy efficiency of extraction. Glucose-based silica, as an adsorbent, was prepared using a simple method, and was proposed for the adsorption of water from water-ethanol mixtures. After adsorption using 0.4 g of adsorbent for 3 h, the initial water concentration of 20 % (water, v/v) was decreased to 10 % (water, v/v). For water concentrations less than 5 % (water, v/v), the adsorbent could concentrate ethanol to 99 % (ethanol, v/v). The Langmuir isotherms used to describe the adsorption of water on an adsorbent showed a correlation coefficient of 0.94. The separation factor of the adsorbent also decreased with decreasing concentration of water in solution. PMID:23299980

Tang, Baokun; Bi, Wentao; Row, Kyung Ho

2013-02-01

298

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

299

Heat--sweat--dehydration--rehydration: a praxis oriented approach.  

PubMed

In any situation where heat production as a result of physical exercise exceeds heat elimination from the body by radiation and convection, the body will depend on sweat secretion and evaporation for its thermoregulation. Sweat secretion will reach maximal levels at high energy expenditures in the heat but will be limited when exercising in the cold climate. Athletes and their coaches should understand some of the principles of thermoregulation in order to make an adequate decision about optimal fluid and carbohydrate replacement in a specific situation. In general it is advised that the carbohydrate content of rehydration drinks should be low (max 80 g l-1) when sweat loss is maximal, may be intermediate when both carbohydrate availability and moderate dehydration influence performance (up to 110 g l-1), and may be maximal (up to 160 g l-1) when the sweat loss is minimized and carbohydrate is the major determinant of the rate of fatigue development. Sodium should be added to rehydration drinks in order to maximize fluid and carbohydrate absorption. A range of electrolyte values for replacement of sweat induced losses, based on whole body wash down procedure is presented. PMID:1895360

Brouns, F

1991-01-01

300

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

301

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

302

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...

303

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...

304

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

305

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

306

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

307

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

308

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...

309

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

DOEpatents

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

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

2011-08-23

310

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 ...

311

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...

312

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

313

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

314

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

315

Bone morphogenetic protein 2 accelerates osteointegration and remodelling of solvent-dehydrated bone substitutes  

Microsoft Academic Search

Introduction lt was the purpose of this study to investigate how bone morphogenetic protein 2 (BMP-2) influences remodelling and the biomechanics of solvent-dehydrated bone in the long run. Furthermore, the early influence of this growth factor on the substitute was investigated. Materials and methods Using a weight-bearing animal model, solvent-dehydrated bone was implanted in the tibial head of merino sheep

S. Kessler; H. E. Koepp; U. Mayr-Wohlfart; A. lgnatius; L. Claes; W. Puhl; K. P. Günther

2004-01-01

316

Effect of Four Drying Methods on the Quality of Osmotically Dehydrated Cranberries  

Microsoft Academic Search

Partially dehydrated cranberries (osmotically dehydrated) were dried to low water contents using one of following four methods: hot air drying; microwave-assisted convective drying; freeze-drying; and vacuum drying. Quality evaluation was performed on all samples, including sensory evaluation (appearance and taste), texture, color, water activity, and rehydration ratio. Hot air drying produced dried cranberries with the best visual appearance while freeze-dried

C. Beaudry; G. S. V. Raghavan; C. Ratti; T. J. Rennie

2004-01-01

317

Plasma membrane lipids in the resurrection plant Ramonda serbica following dehydration and rehydration  

Microsoft Academic Search

Plants of Ramonda serbica were dehydrated to 3.6% relative water content (RWC) by withholding water for 3 weeks, afterwards the plants were rehydrated for 1 week to 93.8% RWC. Plasma membranes were isol- ated from leaves using a two-phase aqueous polymer partition system. Compared with well-hydrated (con- trol) leaves, dehydrated leaves suffered a reduction of about 75% in their plasma

Mike F. Quartacci; Olivera Glisic ´; Branka Stevanovic; Flavia Navari-Izzo

2002-01-01

318

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

319

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

320

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

321

Water loss, cutaneous resistance, and effects of dehydration on locomotion of Eleutherodactylus frogs  

Microsoft Academic Search

Water loss, cutaneous resistance, and the effects of dehydration on jumping ability were measured in two neotropical frogs,\\u000a the common coquí (Eleutherodactylus coqui) and the cave coquí (Eleutherodactylus cooki). In both species jumping performance declined with an increase in water loss and a greater duration of exposure to dehydrating\\u000a conditions. The arboreal species, E. coqui, had a slightly higher rate

G. L. Rogowitz; M. Cortés-Rivera; K. Nieves-Puigdoller

1999-01-01

322

[Oral treatment of acute dehydration in infants by an electrolyte-glucose-solution (author's transl)].  

PubMed

For oral treatment of acute dehydration in infants a solution of electrolytes and glucose in water is indicated. Selfmixing of this solution is not advisable. 30 infants with dehydration caused by acute diarrhoea were treated with a granulat (Normolyt) dissolved in water resulting in a solution of appropriate composition. The solution was well accepted and well tolerated. All babies without clinical signs of shock were successfully rehydrated by the solution. No untoward effects were observed. PMID:463068

Hohenauer, L

1979-06-20

323

Electrostatically enhanced film condensation  

NASA Astrophysics Data System (ADS)

This paper presents a model for film-condensation heat transfer on a general cylindrical surface in the presence of a non-uniform electrostatic field. The steady-state liquid-film flow is assumed to be fully developed and smooth. The liquid is electrically non-conducting. The vapor in contact with the film is pure and saturated. Two experiments in which R113 is condensed in a tube are also described. In one case condensation occurs in an asymmetric electric field as described by the model. In the other case, done for comparison, it occurs in an axisymmetric one. Average heat-transfer measurements and visual observations are reported in both cases. Comparison of the theory with the first experiment is good, despite the model not accounting for the film's waviness.

Joos, F. M.; Snaddon, R. W. L.

1985-07-01

324

Enhanced condensation heat transfer  

NASA Astrophysics Data System (ADS)

Work has centered on optimizing the design variables associated with fluted surfaces on vertical tubes and comparing the tube performance with available enhanced tubes either for vertical or horizontal operation. Data with seven fluids including a hydrocarbon, fluorocarbons, and ammonia condensing on up to 30 different tubes were obtained. Data for tubes of different effective lengths (1/2 to 4 ft) and inclination were also obtained. The primary conclusion is that the best fluted tubes can provide an enhancement in condensation coefficient by a factor of approximately 6 over smooth vertical tube performance and a factor of approximately 2 over the best enhanced commercial tubes either operating vertically or horizontally. These data, together with field test data, have formed the basis for designing two prototype condensers, one for the 60 kWe Raft River, Idaho, pilot plant and one for the 500 kWe East Mesa, California, direct contact demonstration plant.

Michel, J. W.; Murphy, R. W.

1980-07-01

325

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

326

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

327

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

328

Proteomics approach to identify dehydration responsive nuclear proteins from chickpea (Cicer arietinum L.).  

PubMed

Dehydration or water-deficit is one of the most important environmental stress factors that greatly influences plant growth and development and limits crop productivity. Plants respond and adapt to such stress by altering their cellular metabolism and activating various defense machineries. Mechanisms that operate signal perception, transduction, and downstream regulatory events provide valuable information about the underlying pathways involved in environmental stress responses. The nuclear proteins constitute a highly organized, complex network that plays diverse roles during cellular development and other physiological processes. To gain a better understanding of dehydration response in plants, we have developed a comparative nuclear proteome in a food legume, chickpea (Cicer arietinum L.). Three-week-old chickpea seedlings were subjected to progressive dehydration by withdrawing water and the changes in the nuclear proteome were examined using two-dimensional gel electrophoresis. Approximately 205 protein spots were found to be differentially regulated under dehydration. Mass spectrometry analysis allowed the identification of 147 differentially expressed proteins, presumably involved in a variety of functions including gene transcription and replication, molecular chaperones, cell signaling, and chromatin remodeling. The dehydration responsive nuclear proteome of chickpea revealed a coordinated response, which involves both the regulatory as well as the functional proteins. This study, for the first time, provides an insight into the complex metabolic network operating in the nucleus during dehydration. PMID:17921517

Pandey, Aarti; Chakraborty, Subhra; Datta, Asis; Chakraborty, Niranjan

2008-01-01

329

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

330

Simulation of Dehydration Injury to Membranes from Soybean Axes by Free Radicals 1  

PubMed Central

Smooth microsomal membranes were isolated from axes of soybean (Glycine max L. Merr.) seeds at the dehydration-tolerant (6 hours of imbibition) and dehydration-susceptible (36 hours of imbibition) stages of development and were exposed to free radicals in vitro using xanthine-xanthine oxidase as a free radical source. Wide angle x-ray diffraction studies indicated that the lipid phase transition temperature of the microsomal membranes from the dehydration-tolerant axes increased from 7 to 14°C after exposure to free radicals, whereas those from the dehydration-susceptible axes increased from 9 to 40°C by the same free radical dose. The increased phase transition temperature was associated with a decrease in the phospholipid:sterol ratio, and an increase in the free fatty acid:phospholipid ratio. There was no significant change in total fatty acid saturation, which indicated that free radical treatment induced deesterification of membrane phospholipid, and not a change in fatty acid saturation. Similar compositional and structural changes have been previously observed in dehydration-injured soybean axes suggesting that dehydration may induce free radical injury to cellular membranes. Further, these membranes differ in their susceptibility to free radical injury, presumably reflecting compositional differences in the membrane since these membranes were exposed to free radicals in the absence of cytosol. Images Fig. 1 PMID:16664077

Senaratna, Tissa; McKersie, Bryan D.; Stinson, Robert H.

1985-01-01

331

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

2012-10-27

332

Keeping condensers clean  

SciTech Connect

The humble condenser is among the biggest contributors to a steam power plant's efficiency. But although a clean condenser can provide great economic benefit, a dirty one can raise plant heat rate, resulting in large losses of generation revenue and/or unnecessarily high fuel bills. Conventional methods for cleaning fouled tubes range form chemicals to scrapers to brushes and hydro-blasters. This article compares the available options and describes how one power station, Omaha Public Power District's 600 MW North Omaha coal-fired power station, cleaned up its act. The makeup and cooling water of all its five units comes from the Missouri River. 6 figs.

Wicker, K.

2006-04-15

333

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

334

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 ...

Brown, Miss

2009-10-21

335

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

336

Reaction Between Aluminum Nitrate Nonahydrate and Tetraethoxysilane in Ethanol  

Microsoft Academic Search

The reaction between aluminum nitrate nonahydrate and tetraethoxysilane in ethanol was followed by NMR of the Si nucleus. The results showed the initial hydrolysis and condensation to be fast to an extent that no monomeric species of the silicon compounds were found after mixing for three minutes.In addition, the results showed the condensation reaction to be fast compared to the

Johan Sjöblom; Stig E. Friberg; Ali Amran

1995-01-01

337

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

338

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

339

Continuous freezing condenser for phthalic anhydride. [Patented  

SciTech Connect

The increasing outputs of plastics and polymer materials necessitate correspondingly larger outputs of various organic monomers. Phthalic anhydride is one of the source products for organic synthesis. Phthalic anhydride is made in the coking industry by the catalytic vapor-phase oxidation of naphthalene. The product is difficult to isolate from the reaction mixture leaving the static-bed catalytic reactors, since the volume of gases and vapors to be cooled is very large and the phthalic anhydride concentration in the mixture is very low. Continuous freezing condensers have been developed, in which the gas stream is cooled by counterflow contact with a stream of solid granular material on which the phthalic anhydride is condensed. One serious drawback is the need to expend large amounts of heat to remelt the phthalic anhydride crystals. The low strength of the granulated solid substrate leads to dust formation in operation, and the dust contaminates the product. We have developed a condenser in which the freezing and remelting stages take place on metal balls in the same unit and the heat is derived from the incoming reaction mixture. Accordingly, units of large capacity can be constructed giving a higher product yield and lowering the heat consumption in the remelting stage.

Korobchanskii, V.I.; Grebenyuk, A.F.; Korobchanskii, Yu.V.; Il'in, A.P.

1981-01-01

340

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

341

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

342

An Efficient One?Pot Biginelli Condensation of Aliphatic Aldehydes Catalyzed by Zinc Bromide under Solvent?Free Conditions  

Microsoft Academic Search

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

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

2007-01-01

343

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

344

Dehydration of hydrous minerals and formation of nanocrystals by frictional heating in experimental seismic fault zones  

NASA Astrophysics Data System (ADS)

Recent studies on experimental and natural carbonate faults have shown that the formation of nanocrystals produced by thermal decomposition or deformation during seismic slip can lead to significant slip weakening and large earthquakes. Natural fault rocks contain various hydrous minerals that can be easily decomposed by frictional heating and possibly form nanocrystals. However, thermal decomposition of hydrous minerals during seismic slip has not been studied much. We performed rotary-shear experiments on amphibolites and metapelites at seismic slip rates (up to 1.3 m/s) and at normal stress of 2-16 MPa to investigate thermal decomposition of hydrous minerals. The frictional property of the metapelites is characterized by two transient peak frictions followed by a final slip weakening leading to a steady-state friction, while the amphibolites exhibit three peak frictions and subsequent steady-state friction. The simulated fault zones consist of a principal slip zone (PSZ) mantled by damage zone (DZ). The PSZ is a molten layer laden with clasts of quartz (metapelites) and plagioclase (amphibolites). Hornblendes of the amphibolites and biotites of the metapelites in DZ show dark stripes along cleavage planes in plane-polarized light (PPL). These hornblende and biotite grains become totally dark in PPL immediately adjacent to PSZ. Scanning electron microscopy (SEM) shows that tiny holes (1 to 10 ?m) occur in dark colored biotites of DZ. The darker stripes of hornblende appear rugged in SEM images. Selected area electron diffraction (SAED) and high-resolution transmission electron microscope (HRTEM) analyses reveal that the dark cleavage stripes of biotite and hornblende consist of cavity- and nanocrystal-bands. We interpret these cavity- and nanocrystal-bands of the dark cleavage stripes are products of biotite- and hornblende-dehydration preferably occurring along cleavage planes. We believe nanocrystals not only lower friction but also facilitate reaction and/or melting during seismic slip and thus the behavior of nanocrystals is important for understanding earthquake fault motion.

Jung, S.; Chae, S.; Ree, J.; Hirose, T.; Kim, J.

2013-12-01

345

Crustal heterogeneity in the 2000 western Tottori earthquake region: effect of fluids from slab dehydration  

NASA Astrophysics Data System (ADS)

In order to understand the generating mechanism of the western Tottori earthquake ( M 7.3) that occurred on 6 October 2000 in southwest Japan, we determined high-resolution 3D P- and S-wave velocity and Poisson's ratio structures in the epicentral area. We used 17,542 P- and 13,831 S-wave high-quality arrival times from 721 Tottori aftershocks and other local microearthquakes recorded by the dense High-Sensitivity Seismic Network (Hi-net) installed recently on the Japan Islands. Significant variations of up to 4% for seismic velocity and 9% for Poisson's ratio are revealed in the aftershock area. Areas with large coseismic slips and high aftershock activity are associated with high P-wave velocity ( VP), high Poisson's ratio and high electrical conductivity, which may represent strong and competent parts of the fault zone containing fluids. The western Tottori mainshock hypocenter is located in a boundary zone where both velocity and Poisson's ratio change drastically. Both P- and S-wave velocities are slower in the lower crust under the mainshock hypocenter, and low-frequency microearthquakes were detected within the slow anomalies around the Moho discontinuity before and after the occurrence of the 2000 western Tottori earthquake. These results and other related evidence suggest that the strong crustal heterogeneity in the western Tottori source area is associated with fluids and arc magma under nearby the Daisen volcano, which may have influenced the nucleation and rupture process of the western Tottori earthquake. The arc magma and fluids are thought to result from the dehydration reactions of the subducting Philippine Sea slab in this region. These results suggest that the nucleation of shallow earthquakes could be controlled by a deep structure and regime and so it is important to study the deeper crust and upper mantle structure and processes for clarifying the generating mechanism of large crustal earthquakes.

Zhao, Dapeng; Tani, H.; Mishra, O. P.

2004-07-01

346

The postnatal emergence of dehydration anorexia in rats is temporally associated with the emergence of dehydration-induced inhibition of gastric emptying.  

PubMed

Osmotic dehydration produced by systemic hypertonic NaCl (HS) inhibits gastric motility and emptying and also inhibits feeding in adult rats. Conversely, in neonatal rats, dehydration does not inhibit feeding. The present study examined whether the postnatal emergence of dehydration anorexia is temporally associated with the emergence of dehydration-induced inhibition of gastric emptying. Rat pups 4 to 19 days old were injected subcutaneously with HS (0.75 M NaCl; 200 microL/10 g body weight). Control rats were injected with isotonic saline (0.15 M NaCl). Thirty minutes later, rats were given access to milk that could be lapped from paper towels on the floor of a warm testing chamber. Other HS-treated and control rats were given an intragastric load of 0.15 M NaCl (2% body weight) and then killed after 30 min to determine how much of the load had emptied from the stomach. Consistent with previous reports, HS-treated rats consumed significantly more milk than control rats from postnatal Day 4 (P4) through P11 but consumed significantly less milk than controls at P19. HS treatment did not affect gastric emptying of 0.15 M NaCl at P4 or P11. Conversely, HS treatment significantly inhibited gastric emptying at P19. These findings suggest that the hypophagic effects of dehydration develop in tandem with inhibitory effects on gastric motility and are consistent with the view that the full complement of mature homeostatic responses to plasma hyperosmolality requires coordinated activation of forebrain and hindbrain neural circuits that are only partially formed in neonatal rats. PMID:9817581

Callahan, J B; Rinaman, L

1998-07-01

347

Transcriptome sequencing and whole genome expression profiling of chrysanthemum under dehydration stress  

PubMed Central

Background Chrysanthemum is one of the most important ornamental crops in the world and drought stress seriously limits its production and distribution. In order to generate a functional genomics resource and obtain a deeper understanding of the molecular mechanisms regarding chrysanthemum responses to dehydration stress, we performed large-scale transcriptome sequencing of chrysanthemum plants under dehydration stress using the Illumina sequencing technology. Results Two cDNA libraries constructed from mRNAs of control and dehydration-treated seedlings were sequenced by Illumina technology. A total of more than 100 million reads were generated and de novo assembled into 98,180 unique transcripts which were further extensively annotated by comparing their sequencing to different protein databases. Biochemical pathways were predicted from these transcript sequences. Furthermore, we performed gene expression profiling analysis upon dehydration treatment in chrysanthemum and identified 8,558 dehydration-responsive unique transcripts, including 307 transcription factors and 229 protein kinases and many well-known stress responsive genes. Gene ontology (GO) term enrichment and biochemical pathway analyses showed that dehydration stress caused changes in hormone response, secondary and amino acid metabolism, and light and photoperiod response. These findings suggest that drought tolerance of chrysanthemum plants may be related to the regulation of hormone biosynthesis and signaling, reduction of oxidative damage, stabilization of cell proteins and structures, and maintenance of energy and carbon supply. Conclusions Our transcriptome sequences can provide a valuable resource for chrysanthemum breeding and research and novel insights into chrysanthemum responses to dehydration stress and offer candidate genes or markers that can be used to guide future studies attempting to breed drought tolerant chrysanthemum cultivars. PMID:24074255

2013-01-01

348

Switching control of sympathetic activity from forebrain to hindbrain in chronic dehydration  

PubMed Central

Abstract We investigated the mechanisms responsible for increased blood pressure and sympathetic nerve activity (SNA) caused by 2–3 days dehydration (DH) both in vivo and in situ preparations. In euhydrated (EH) rats, systemic application of the AT1 receptor antagonist Losartan and subsequent pre-collicular transection (to remove the hypothalamus) significantly reduced thoracic (t)SNA. In contrast, in DH rats, Losartan, followed by pre-collicular and pontine transections, failed to reduce tSNA, whereas transection at the medulla–spinal cord junction massively reduced tSNA. In DH but not EH rats, selective inhibition of the commissural nucleus tractus solitarii (cNTS) significantly reduced tSNA. Comparable data were obtained in both in situ and in vivo (anaesthetized/conscious) rats and suggest that following chronic dehydration, the control of tSNA transfers from supra-brainstem structures (e.g. hypothalamus) to the medulla oblongata, particularly the cNTS. As microarray analysis revealed up-regulation of AP1 transcription factor JunD in the dehydrated cNTS, we tested the hypothesis that AP1 transcription factor activity is responsible for dehydration-induced functional plasticity. When AP1 activity was blocked in the cNTS using a viral vector expressing a dominant negative FosB, cNTS inactivation was ineffective. However, tSNA was decreased after pre-collicular transection, a response similar to that seen in EH rats. Thus, the dehydration-induced switch in control of tSNA from hypothalamus to cNTS seems to be mediated via activation of AP1 transcription factors in the cNTS. If AP1 activity is blocked in the cNTS during dehydration, sympathetic activity control reverts back to forebrain regions. This unique reciprocating neural structure-switching plasticity between brain centres emphasizes the multiple mechanisms available for the adaptive response to dehydration. PMID:21708906

Colombari, Débora S A; Colombari, Eduardo; Freiria-Oliveira, Andre H; Antunes, Vagner R; Yao, Song T; Hindmarch, Charles; Ferguson, Alastair V; Fry, Mark; Murphy, David; Paton, Julian F R

2011-01-01

349

Switching control of sympathetic activity from forebrain to hindbrain in chronic dehydration.  

PubMed

We investigated the mechanisms responsible for increased blood pressure and sympathetic nerve activity (SNA) caused by 2-3 days dehydration (DH) both in vivo and in situ preparations. In euhydrated (EH) rats, systemic application of the AT(1) receptor antagonist Losartan and subsequent pre-collicular transection (to remove the hypothalamus) significantly reduced thoracic (t)SNA. In contrast, in DH rats, Losartan, followed by pre-collicular and pontine transections, failed to reduce tSNA, whereas transection at the medulla-spinal cord junction massively reduced tSNA. In DH but not EH rats, selective inhibition of the commissural nucleus tractus solitarii (cNTS) significantly reduced tSNA. Comparable data were obtained in both in situ and in vivo (anaesthetized/conscious) rats and suggest that following chronic dehydration, the control of tSNA transfers from supra-brainstem structures (e.g. hypothalamus) to the medulla oblongata, particularly the cNTS. As microarray analysis revealed up-regulation of AP1 transcription factor JunD in the dehydrated cNTS, we tested the hypothesis that AP1 transcription factor activity is responsible for dehydration-induced functional plasticity. When AP1 activity was blocked in the cNTS using a viral vector expressing a dominant negative FosB, cNTS inactivation was ineffective. However, tSNA was decreased after pre-collicular transection, a response similar to that seen in EH rats. Thus, the dehydration-induced switch in control of tSNA from hypothalamus to cNTS seems to be mediated via activation of AP1 transcription factors in the cNTS. If AP1 activity is blocked in the cNTS during dehydration, sympathetic activity control reverts back to forebrain regions. This unique reciprocating neural structure-switching plasticity between brain centres emphasizes the multiple mechanisms available for the adaptive response to dehydration. PMID:21708906

Colombari, Débora S A; Colombari, Eduardo; Freiria-Oliveira, Andre H; Antunes, Vagner R; Yao, Song T; Hindmarch, Charles; Ferguson, Alastair V; Fry, Mark; Murphy, David; Paton, Julian F R

2011-09-15

350

Water Temperature, Voluntary Drinking and Fluid Balance in Dehydrated Taekwondo Athletes  

PubMed Central

Voluntary drinking is one of the major determiners of rehydration, especially as regards exercise or workout in the heat. The present study undertakes to search for the effect of voluntary intake of water with different temperatures on fluid balance in Taekwondo athletes. Six young healthy male Taekwondo athletes were dehydrated by moderate exercise in a chamber with ambient temperature at 38-40°C and relative humidity between 20-30%. On four separate days they were allowed to drink ad libitum plane water with the four temperatures of 5, 16, 26, and 58°C, after dehydration. The volume of voluntary drinking and weight change was measured; then the primary percentage of dehydration, sweat loss, fluid deficit and involuntary dehydration were calculated. Voluntary drinking of water proved to be statistically different in the presented temperatures. Water at 16°C involved the greatest intake, while fluid deficit and involuntary dehydration were the lowest. Intake of water in the 5°C trial significantly correlated with the subject’s plasma osmolality change after dehydration, yet it showed no significant correlation with weight loss. In conclusion, by way of achieving more voluntary intake of water and better fluid state, recommending cool water (~16°C) for athletes is in order. Unlike the publicly held view, drinking cold water (~5°C) does not improve voluntary drinking and hydration status. Key points For athletes dehydrated in hot environments, maximum voluntary drinking and best hydration state occurs with 16°C water. Provision of fluid needs and thermal needs could be balanced using 16°C water. Drinking 16°C water (nearly the temperature of cool tap water) could be recommended for exercise in the heat. PMID:24149564

Khamnei, Saeed; Hosseinlou, Abdollah; Zamanlu, Masumeh

2011-01-01

351

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

352

Crustal recycling, mantle dehydration, and the thermal evolution of Mars  

NASA Astrophysics Data System (ADS)

We have reinvestigated the coupled thermal and crustal evolution of Mars taking new laboratory data concerning the flow behavior of iron-rich olivine into account. The low mantle viscosities associated with the relatively higher iron content of the martian mantle as well as the observed high concentrations of heat producing elements in a crust with a reduced thermal conductivity were found to promote phases of crustal recycling in many models. As crustal recycling is incompatible with an early separation of geochemical reservoirs, models were required to show no episodes of crustal recycling. Furthermore, admissible models were required to reproduce the martian crust formation history, to allow for the formation of partial melt under present day mantle conditions and to reproduce the measured concentrations of potassium and thorium on the martian surface. Taking dehydration stiffening of the mantle viscosity by the extraction of water from the mantle into account, we found that admissible models have low initial upper mantle temperatures around 1650 K, preferably a primordial crustal thickness of 30 km, and an initially wet mantle rheology. The crust formation process on Mars would then be driven by the extraction of a primordial crust after core formation, cooling the mantle to temperatures close to the peridotite solidus. According to this scenario, the second stage of global crust formation took place over a more extended period of time, waning at around 3500 Myr b.p., and was driven by heat produced by the decay of radioactive elements. Present-day volcanism would then be driven by mantle plumes originating at the core-mantle boundary under regions of locally thickened, thermally insulating crust. Water extraction from the mantle was found to be relatively efficient and close to 40% of the total inventory was lost from the mantle in most models. Assuming an initial mantle water content of 100 ppm and that 10% of the extracted water is supplied to the surface, this amount is equivalent to a 14 m thick global surface layer, suggesting that volcanic outgassing of H 2O could have significantly influenced the early martian climate and increased the planet's habitability.

Morschhauser, A.; Grott, M.; Breuer, D.

2011-04-01

353

Tracking the dehydration process of raw honey by synchronous two-dimensional near infrared correlation spectroscopy  

NASA Astrophysics Data System (ADS)

Though much attention is paid to honey quality assessment, few reports on characteristic of manually dehydrated honey have been found. The aim of this investigation is to track the dehydration process of raw honey using synchronous two-dimensional (2D) near infrared correlation spectroscopy. To minimize the impact of dehydration to honey quality, seventy-two honey samples from six different dehydration stages were obtained using drum wind drying method with temperature controlled at 40 °C. Their dynamic short-wave NIR spectra from 600 to 1100 nm were collected in the transmission mode from 10 to 50 °C with an increment of 5 °C and were analyzed using synchronous two-dimensional correlation method. Short-wave NIR spectral data has been exploited less than other NIR region for its weaker signal especially for water absorption's interference with useful information. The investigation enlarged the signal at this band using synchronous 2D correlation analysis, revealing the fingerprinting feature of rape honey and chaste honey during the artificial dehydration process. The results have shown that, with the help of 2D correlation analysis, this band can detect the variation of the second overtone of O-H and N-H groups vibration upon their H-bonds forming or collapsing resulted from the interactions between water and solute. The results have also shown that 2D-NIRS method is able to convert the tiny changes in honey constituents into the detectable fingerprinting difference, which provides a new method for assessing honey quality.

Chen, Guiyun; Sun, Xin; Huang, Yuping; Chen, Kunjie

2014-11-01

354

Colour, phenolic content and antioxidant capacity of some fruits dehydrated by a combination of different methods.  

PubMed

The objective of this study was to improve product quality of dehydrated fruits (apple, pear, papaya, mango) using combined drying techniques. This involved investigation of bioactivity, colour, and sensory assessment on colour of the dried products as well as the retention of the bio-active ingredients. The attributes of quality were compared in regard to the quality of dehydrated samples obtained from continuous heat pump (HP) drying technique. It was found that for apple, pear and mango the total colour change (?E) of samples dried using continuous heat pump (HP) or heat pump vacuum-microwave (HP/VM) methods was lower than of samples dried by other combined methods. However, for papaya, the lowest colour change exhibited by samples dried using hot air-cold air (HHC) method and the highest colour change was found for heat pump (HP) dehydrated samples. Sensory evaluation revealed that dehydrated pear with higher total colour change (?E) is more desirable because of its golden yellow appearance. In most cases the highest phenol content was found from fruits dried by HP/VM method. Judging from the quality findings on two important areas namely colour and bioactivity, it was found that combined drying method consisted of HP pre-drying followed by VM finish drying gave the best results for most dehydrated fruits studied in this work as the fruits contain first group of polyphenol compounds, which preferably requires low temperature followed by rapid drying strategy. PMID:23993562

Chong, Chien Hwa; Law, Chung Lim; Figiel, Adam; Wojdy?o, Aneta; Oziemb?owski, Maciej

2013-12-15

355

A New Freezing Method Using Pre-Dehydration by Microwave-Vacuum Drying  

NASA Astrophysics Data System (ADS)

Partial dehydration by microwave-vacuum drying has been applied to tuna and strawberry in order to reduce cell-damages caused by the formation of large ice-crystals during freezing. The samples were subjected to microwave vacuum drying at pressure of 5 kPa and temperature less than 27°C to remove small amount of water prior to freezing. The tuna were cooled by using the freezing chamber at temperature -50°C or -150°C, while the strawberries were frozen at temperature -30°C or -80°C, respectively. The temperature transients in tuna showed that removing some water before freezing made the freezing time shorter. The observations of ice crystal clearly indicated that rapid cooling and pre-dehydration prior to freezing were effective in minimizing the size of ice crystal. It is also understood that the formation of large ice crystals has a close relation to the cell damages. After thawing, the observation of microstructure was done on the tuna and strawberry halves. The pre-dehydrated samples showed a better structure than the un-dehydrated one. It is concluded that the pre-dehydration by microwave-vacuum drying is one promising method for the cryo-preservation of foods.

Tsuruta, Takaharu; Hamidi, Nurkholis

356

Condensed Plasmas under Microgravity  

Microsoft Academic Search

Experiments under microgravity conditions were carried out to study ``condensed'' (liquid and crystalline) states of a colloidal plasma (ions, electrons, and charged microspheres). Systems with ~106 microspheres were produced. The observed systems represent new forms of matter-quasineutral, self-organized plasmas-the properties of which are largely unexplored. In contrast to laboratory measurements, the systems under microgravity are clearly three dimensional (as expected);

G. E. Morfill; H. M. Thomas; U. Konopka; H. Rothermel; M. Zuzic; A. Ivlev; J. Goree

1999-01-01

357

Economical Condensing Turbines?  

E-print Network

.19 per condensed needed steam including exit 1000# btu per million million Btu water Btu/# loss, Btu/# kwh Btu 1,261 1,570 895 450 87.8 17,885 $ 0.033 $ 0.057 1,221 1,519 903 402 78.3 19,406 $ 0.036 $ 0.062 1,211 1,506 913 382 74.4 20,260 $ 0...

Dean, J. E.

358

Calculation of dropwise condensation  

NASA Astrophysics Data System (ADS)

The problem of drop growth is solved by the method of variable directions. It is shown that as the contact angle of wetting increases, the amount of heat transferred through the drop is reduced. This suggests that there is an optimum contact angle corresponding to the highest efficiency of a water-repelling layer. It is also shown that calculations of the initial stages of dropwise condensation should include the effects of convective heat transfer.

Tokar, I. Ia.; Sirenko, V. A.; Iurchenko, N. P.

1981-07-01

359

Five-membered ring annelation in [2.2]paracyclophanes by aldol condensation  

PubMed Central

Summary Under basic conditions 4,5,12,13-tetraacetyl[2.2]paracyclophane (9) cyclizes by a double aldol condensation to provide the two aldols 12 and 15 in a 3:7 ratio. The structures of these compounds were obtained from X-ray structural analysis, spectroscopic data, and mechanistic considerations. On acid treatment 12 is dehydrated to a mixture of the condensed five-membered [2.2]paracyclophane derivatives 18–20, whereas 15 yields a mixture of the isomeric cyclopentadienones 21–23. The structures of these elimination products are also deduced from X-ray and spectroscopic data. The sequence presented here constitutes the simplest route so far to cyclophanes carrying an annelated five-membered ring. PMID:25246961

Narayanan, Swaminathan Vijay; Jones, Peter G

2014-01-01

360

Apex cryopreservation of several strawberry genotypes by two encapsulation-dehydration methods.  

PubMed

This paper presents results from a study to develop cryopreservation procedures for apices of several strawberry genotypes. Five Fragaria x ananassa Duch. cultivars and two wild species (F. chiloensis and F. virginiana) have been screened using the encapsulation-dehydration method and/or a protocol which compromises vitrification and encapsulation-dehydration. Apices were encapsulated in an alginate gel, precultured on media containing high levels of sucrose (0.8 M, conventional protocol), or a combination of 0.4 M sucrose and 2 M glycerol. Recovery rates varied among genotypes (23-63%). The latter method reduced considerably the time needed for the cryogenic procedure by eliminating the pre-treatment with 0.8 M sucrose for 19 h prior to dehydration, as required by the conventional procedure. PMID:15772709

Clavero-Ramírez, I; Gálvez-Farfán, J; López-Aranda, J M; González-Benito, M E

2005-01-01

361

Molybdenum oxides as highly effective dehydrative cyclization catalysts for the synthesis of oxazolines and thiazolines.  

PubMed

In the presence of molybdenum oxide the dehydrative cyclization of N-acylserines, N-acylthreonines, and N-acylcysteines can be carried out under Dean-Stark conditions in toluene to give oxazolines and thiazolines. The ammonium salts (NH(4))(6)Mo(7)O(24).4H(2)O and (NH(4))(2)MoO(4) have excellent catalytic activities for the dehydrative cyclization of serine and threonine derivatives, and the acetylacetonate complex MoO(2)(acac)(2) has a remarkable catalytic activity for the dehydrative cyclization of cysteine derivatives. In addition, polyaniline-supported MoO(2)(acac)(2) can easily be recovered and reused. PMID:15876032

Sakakura, Akira; Kondo, Rei; Ishihara, Kazuaki

2005-05-12

362

Synthesis of butenes through 2-butanol dehydration over mesoporous materials produced from ferrierite  

SciTech Connect

Mesoporous materials synthesized from commercial ferrierite (MMZ-FER) were applied to butanol dehydration. The MMZ-FER was produced by disassembling ferrierite into unit structures in the presence of an alkali solution, adding a surfactant as a templating material, followed by hydrothermal treatment. The effect of the alkali/(Si+Al) ratio in the disassembling step on the characteristics of the catalyst and butanol dehydration performance were investigated. The MMZ-FER materials, synthesized in a condition in which the NaOH/(Si + Al) mole ratio in the disassembling step was 0.67 and 1.0, demonstrated similar textural properties to those of MCM-41. Many weak acid sites developed on the MMZ-FER(0.67) and MMZ-FER(1.0) samples, which is attributed to the creation of ferrierite-induced acid sites. The MMZ-FER materials showed excellent catalytic activity, selectivity, and stability during the dehydration of 2-butanol.

Jeong, Soyeon; Kim, Hyeonjoo; Bae, Jung A.; Kim, Do Heui; Peden, Charles HF; Park, Young-Kwon; Jeon, Jong Ki

2012-05-20

363

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

364

Dehydration kinetics and thermochemistry of selected hydrous phases, and simulated gas release pattern in carbonaceous chondrites  

NASA Technical Reports Server (NTRS)

As part of our continued program of study on the volatile bearing phases and volatile resource potential of carbonaceous chondrite, results of our experimental studies on the dehydration kinetics of talc as a function of temperature and grain size (50 to 0.5 microns), equilibrium dehydration boundary of talc to 40 kbars, calorimetric study of enthalpy of formation of both natural and synthetic talc as a function of grain size, and preliminary results on the dehydration kinetics of epsomite are reported. In addition, theoretical calculations on the gas release pattern of Murchison meteorite, which is a C2(CM) carbonaceous chondrite, were performed. The kinetic study of talc leads to a dehydration rate constant for 40-50 microns size fraction of k = (3.23 x 10(exp 4))exp(-Q/RT)/min with the activation energy Q = 376 (plus or minus 20) kJ/mole. The dehydration rate was found to increase somewhat with decreasing grain size. The enthalpy of formation of talc from elements was measured to be -5896(10) kJ/mol. There was no measurable effect of grain size on the enthalpy beyond the limits of precision of the calorimetric studies. Also the calorimetric enthalpy of both synthetic and natural talc was found to be essentially the same, within the precision of measurements, although the natural talc had a slightly larger field of stability in our phase equilibrium studies. The high pressure experimental data the dehydration equilibrium of talc (talc = enstatite + coesite + H2O) is in strong disagreement with that calculated from the available thermochemical data, which were constrained to fit the low pressure experimental results. The calculated gas release pattern of Murchison meteorite were in reasonable agreement with that determined by stepwise heating in a gas chromatograph.

Bose, Kunal; Ganguly, J.

1992-01-01

365

Onset, extent, and duration of dehydration in the Southern Hemisphere polar vortex  

NASA Astrophysics Data System (ADS)

Satellite observations of water vapor and aerosol extinction along with temperature trajectory calculations are analyzed for the Southern Hemisphere winter of 1992 in order to determine the onset, extent, and duration of dehydration within the polar vortex. Our investigation uses measurements of water vapor from the Microwave Limb Sounder (MLS) and aerosol extinction from the Cryogenic Limb Array Etalon Spectrometer (CLAES), both on board the Upper Atmosphere Research Satellite (UARS). Evidence of persistent ice cloud formation, supported by temperature statistics obtained from air parcel trajectories, suggests that the onset of the dehydration process occurs between late June and early July. By late August-early September water vapor depleted areas within the vortex no longer coincide with high aerosol extinctions, indicating that severe dehydration has occurred with the irreversible removal of water vapor over vast areas. Areas with depleted levels of water vapor, below the prewinter values, persist well into November. Evidence for dehydration is found on potential temperature surfaces from 420 K (the lower limit of the MLS measurements) to 520 K (approximately 16 to 22 km). The horizontal extent of the dehydrated area at 465 K encompasses up to 35% of the total vortex area equatorward of 80°S. A comparison of CLAES aerosol extinction measurements and model calculations of aerosol extinction suggests an average ice particle number concentration and size of 10-2-10-3 cm-3 and 10-30 ?m, respectively. We show that the difference between the timing of the onset of dehydration found here and that in a recent analysis of Polar Ozone and Aerosol Measurement III (POAM) observations can be explained by the latitudinal sampling pattern of the POAM instrument.

Stone, Elizabeth M.; Tabazadeh, Azadeh; Jensen, Eric; Pumphrey, Hugh C.; Santee, Michelle L.; Mergenthaler, John L.

2001-10-01

366

Crustal Recycling, Mantle Dehydration and the Thermal Evolution of Mars  

NASA Astrophysics Data System (ADS)

We have reinvestigated the coupled thermal and crustal evolution of Mars using 1D parametrized thermal evolution models [1] and taking new data concerning the content and distribution of heat producing elements [2] as well as new laboratory data concerning the flow behavior of iron-rich olivine [3] into account. The high enrichment of radioactive elements in the crust leads to a less efficient heat transport from the lithospheric base, resulting in a thinning of the stagnant lid. If the stagnant lid becomes thinner than the crust, crustal material can be recycled back into the mantle by the vigourous convective motion. However, crustal recycling appears to be incompatible with an early separation of geochemical reservoirs [4] and valid models are required to show no episodes of crustal recycling. Furthermore, admissible models have to reproduce the Martian crust formation history and to allow the formation of partial melt under present-day mantle conditions. Taking dehydration stiffening of the mantle into account, we find that admissible models have low initial upper mantle temperatures between 1600 and 1700 K, a primordial crustal thickness of 30 km, and an initially wet mantle rheology. The crust formation process on Mars would then have been driven by the extraction of a primordial crust after core formation which was cooling the mantle to temperatures close to the peridotite solidus. The second stage of global crust formation took place over a more extended period of time, waning at around 1300-1700 Myr, and was driven by heat produced by the decay of radioactive elements. Finally, present-day volcanism is explained by convective mantle plumes and thermal insulation under regions of locally thickened crust. Water extraction from the mantle was found to be relatively efficient and close to 50 percent of the total inventory is lost from the mantle in most models. Assuming an initial mantle water content of 100 ppm and that 10% of the extracted water is supplied to the surface by extrusive volcanism, this amount is equivalent to a 20 m thick global surface layer, suggesting that volcanic outgassing of H2O could have significantly influenced the early Martian climate and increased the planet's habitability. To further investigate the potential for an early wet and warm Mars, we self-consistently calculate the amount of volcanically outgassed CO2. This is done by directly coupling thermodynamic models of CO2 solubility in basaltic melt [5] to the thermal evolution models. Using the range of admissible models, we find that an equivalent of 1 bar of CO2 can be outgassed if the redox state of the mantle is assumed to be at the upper limit of the plausible range (IW+1). This is probably sufficient to raise the mean global surface temperature above the triple point of water [6]. However, erosive processes could have been very strong under an active young sun, thus leading to considerable atmospheric loss within the Noachian period [7]. [1] Breuer, D and Spohn, T, PSS, 54, 153, 2006. [2] Taylor, GJ et al., JGR, 111, E03S10, 2006. [3] Zhao, YH et. al., EPSL, 287, 229, 2009. [4] Jagoutz, E, SSR, 56, 13, 1991. [5] Hirschmann, MM and Withers, AC, EPSL, 270, 147, 2008. [6] Forget, F and Pierrehumbert, RT, Sci., 278, 1273-1276, 1997. [7] Tian, F et. al., GRL, 36, L02205, 2009.

Morschhauser, A.; Grott, M.; Breuer, D.

2010-12-01

367

A cDNA-based comparison of dehydration-induced proteins (dehydrins) in barley and corn  

Microsoft Academic Search

Several cDNAs related to an ABA-induced cDNA from barley aleurone were isolated from barley and corn seedlings that were undergoing dehydration. Four different barley polypeptides with sizes of 22.6, 16.2, 14.4 and 14.2 kDa and a single corn polypeptide with a size of 17.0 kDa were predicted from the nucleotide sequences of the cDNAs. These dehydration-induced proteins (dehydrins) are very

Timothy J. Close; Alexander A. Kortt; Peter M. Chandler

1989-01-01

368

Dehydration behavior of FGD gypsum by simultaneous TG and DSC analysis  

Microsoft Academic Search

The dehydration behaviors of FGD gypsums from three power plants were investigated at N2 atmosphere (autogenous and negligible partial pressure of water, $$ P_{{{\\\\text{H}}_{ 2} {\\\\text{O}}}} $$) in non-isothermal and isothermal condition. The dehydration of gypsum proceeded through one step, i.e., CaSO4·2H2O ? ?-CaSO4 (?-anhydrite) or two steps, i.e., CaSO4·2H2O ? CaSO4·0.5H2O (hemihydrate) ? ?-CaSO4 depending on temperature and $$ P_{{{\\\\text{H}}_{ 2} {\\\\text{O}}}} $$. The discrepancies

Wenbin Lou; Baohong Guan; Zhongbiao Wu

2011-01-01

369

Surviving the cold: molecular analyses of insect cryoprotective dehydration in the Arctic springtail Megaphorura arctica (Tullberg)  

PubMed Central

Background Insects provide tractable models for enhancing our understanding of the physiological and cellular processes that enable survival at extreme low temperatures. They possess three main strategies to survive the cold: freeze tolerance, freeze avoidance or cryoprotective dehydration, of which the latter method is exploited by our model species, the Arctic springtail Megaphorura arctica, formerly Onychiurus arcticus (Tullberg 1876). The physiological mechanisms underlying cryoprotective dehydration have been well characterised in M. arctica and to date this process has been described in only a few other species: the Antarctic nematode Panagrolaimus davidi, an enchytraied worm, the larvae of the Antarctic midge Belgica antarctica and the cocoons of the earthworm Dendrobaena octaedra. There are no in-depth molecular studies on the underlying cold survival mechanisms in any species. Results A cDNA microarray was generated using 6,912 M. arctica clones printed in duplicate. Analysis of clones up-regulated during dehydration procedures (using both cold- and salt-induced dehydration) has identified a number of significant cellular processes, namely the production and mobilisation of trehalose, protection of cellular systems via small heat shock proteins and tissue/cellular remodelling during the dehydration process. Energy production, initiation of protein translation and cell division, plus potential tissue repair processes dominate genes identified during recovery. Heat map analysis identified a duplication of the trehalose-6-phosphate synthase (TPS) gene in M. arctica and also 53 clones co-regulated with TPS, including a number of membrane associated and cell signalling proteins. Q-PCR on selected candidate genes has also contributed to our understanding with glutathione-S-transferase identified as the major antioxdidant enzyme protecting the cells during these stressful procedures, and a number of protein kinase signalling molecules involved in recovery. Conclusion Microarray analysis has proved to be a powerful technique for understanding the processes and genes involved in cryoprotective dehydration, beyond the few candidate genes identified in the current literature. Dehydration is associated with the mobilisation of trehalose, cell protection and tissue remodelling. Energy production, leading to protein production, and cell division characterise the recovery process. Novel membrane proteins, along with aquaporins and desaturases, have been identified as promising candidates for future functional analyses to better understand membrane remodelling during cellular dehydration. PMID:19622137

Clark, Melody S; Thorne, Michael AS; Pura?, Jelena; Burns, Gavin; Hillyard, Guy; Popovi?, Željko D; Grubor-Lajši?, Gordana; Worland, M Roger

2009-01-01

370

Dehydration and Symptoms of Delayed-Onset Muscle Soreness in Normothermic Men  

PubMed Central

Context: A dehydrated individual who performs eccentric exercise may exacerbate skeletal muscle damage, leading to structural, contractile, and enzymatic protein denaturation, in addition to the myofiber and connective damage resulting from the eccentric muscle tension. Objective: To identify the effects of dehydration on 5 physiologic characteristics of delayed-onset muscle soreness (DOMS) in normothermic men after an eccentric exercise perturbation. Design: Randomized group test-retest design. Setting: Laboratory. Patients or Other Participants: Ten healthy male volunteers randomly assigned to either a euhydration (age = 26.2 ± 4.9 years, height = 174.1 ± 6.0 cm, mass = 86.5 ± 15.3 kg) or dehydration (age = 25.8 ± 2.2 years, height = 177.2 ± 3.1 cm, mass = 84.4 ± 3.8 kg) group. Intervention(s): Subjects performed treadmill walking for 45 minutes in either a thermoneutral (euhydration) or a hot, humid (dehydration) environment. After a rest period to allow for return to the normothermic condition, DOMS was induced with a 45-minute downhill run. Main Outcome Measures: We assessed 5 physiologic characteristics of DOMS before and at intervals after the eccentric exercise. The characteristics were perceived pain of the bilateral quadriceps and overall body, bilateral punctate tenderness of the superficial quadriceps muscles, bilateral knee-flexion passive range of motion, bilateral thigh circumference, and bilateral isometric quadriceps muscle strength. Thermoregulatory and cardiovascular measures were obtained to monitor participants' heat load during exercise. Results: The experimental protocol produced a 0.9% increase in body mass of the euhydration group and a significant 2.7% decrease in body mass of the dehydration group. The downhill-running exercise perturbation induced DOMS in both the euhydrated and dehydrated participants, based on increased bilateral quadriceps and overall body perceived pain and punctate tenderness of the bilateral vastus medialis muscle. The signs and symptoms of DOMS after an eccentric exercise perturbation were not exacerbated by moderate dehydration of 2.7% body mass after rest and return to the normothermic condition. Conclusions: Significantly dehydrated participants who rested and returned to a normothermic condition did not experience increased characteristics of DOMS. PMID:16619093

Cleary, Michelle A; Sitler, Michael R; Kendrick, Zebulon V

2006-01-01

371

Effect of hydration and dehydration cycles on seed germination of Aster kantoensis (Compositae)  

Microsoft Academic Search

Seeds of Aster kantoensis Kitamura (Compositae) were experimentally exposed to different cycles of hydration and dehydration: 3H1D (cycles of 3-d hydration and 1-d dehydration periods), 2H3D, 2H1D, 1H3D, 1H2D, and 1H1D. Under continuous hydration (control), all viable seeds germinated within 9 d. However, all viable seeds ex- posed to the 3H1D, 2H3D, and 2H1D cycles germinated within 36, 50, and

Mitsuko Kagaya; Takashi Tani; Naoki Kachi

2005-01-01

372

Alcohol Dehydration on Monooxo W=O and Dioxo O=W=O Species  

SciTech Connect

The dehydration of 1-propanol on nanoporous WO3 films prepared via ballistic deposition at ~20 K has been investigated using temperature programmed desorption, infrared reflection absorption spectroscopy and density functional theory. The as deposited films are extremely efficient in 1-propanol dehydration to propene. This activity is correlated with the presence of dioxo O=W=O groups while monooxo W=O species are shown to be inactive. Annealing of the film induces densification that results in the loss of catalytic activity due to annihilation O=W=O species.

Li, Zhenjun; Smid, Bretislav; Kim, Yu Kwon; Matolin, Vladimir; Kay, Bruce D.; Rousseau, Roger J.; Dohnalek, Zdenek

2012-08-16

373

Condensation and Large Cardinals Sy-David Friedman, Peter Holy  

E-print Network

Condensation and Large Cardinals Sy-David Friedman, Peter Holy Abstract We introduce two generalized condensation principles: Local Club Condensation and Stationary Condensation. We show that while Strong Condensation (a generalized Condensation principle intro- duced by Hugh Woodin in [19

374

Natural Zeolites: Cation Exchange, Cation Arrangement and Dehydration Behavior  

Microsoft Academic Search

Still 50 years ago natural zeolites mainly from vugs and fissures of volcanic rocks were considered a rare curiosity of nature.\\u000a About 100 years ago chemists recognized that these minerals with a tetrahedral framework structure, characterized by internal\\u000a porous space in form of cavities and connecting channels, can be used for ion exchange, molecular sieving, and catalytic reactions.\\u000a Thus in

Thomas Armbruster

375

Drug Reactions  

MedlinePLUS

... version Drug Reactions Drug Reactions What is an adverse drug reaction? Medicines can treat or prevent illness and ... medicines can cause problems. These problems are called adverse drug reactions. You should know what to do if ...

376

Confinement Contains Condensates  

SciTech Connect

Dynamical chiral symmetry breaking and its connection to the generation of hadron masses has historically been viewed as a vacuum phenomenon. We argue that confinement makes such a position untenable. If quark-hadron duality is a reality in QCD, then condensates, those quantities that have commonly been viewed as constant empirical mass-scales that fill all spacetime, are instead wholly contained within hadrons; i.e., they are a property of hadrons themselves and expressed, e.g., in their Bethe-Salpeter or light-front wave functions. We explain that this paradigm is consistent with empirical evidence, and incidentally expose misconceptions in a recent Comment.

Brodsky, Stanley J.; Roberts, Craig D.; Shrock, Robert; Tandy, Peter C.

2012-03-12

377

Pion condensation in holographic QCD  

SciTech Connect

We study pion condensation at zero temperature in a hard-wall holographic model of hadrons with isospin chemical potential. We find that the transition from the hadronic phase to the pion condensate phase is first order except in a certain limit of model parameters. Our analysis suggests that immediately across the phase boundary the condensate acts as a stiff medium approaching the Zel'dovich limit of equal energy density and pressure.

Albrecht, Dylan; Erlich, Joshua [Particle Theory Group, Department of Physics, College of William and Mary, Williamsburg, Virginia 23187-8795 (United States)

2010-11-01

378

Dehydration-responsive reversible and irreversible changes in the extracellular matrix: comparative proteomics of chickpea genotypes with contrasting tolerance.  

PubMed

Dehydration is the most crucial environmental factor that limits plant growth, development, and productivity affecting agriculture throughout the world. Studies on genetic variations for dehydration tolerance in plants is crucial because divergent cultivars with contrasting traits aid the identification of key cellular components that confer better adaptability. The extracellular matrix (ECM) is a dynamic structure that serves as the repository for important signaling components and acts as a front-line defense. To better understand dehydration adaptation, a proteomic study was performed on the extracellular matrix of ICCV-2, a dehydration-susceptible genotype of chickpea. The proteome was generated with ECM-enriched fractions using two-dimensional gel electrophoresis. The LC-ESI-MS/MS analysis led to the identification of 81 dehydration-responsive proteins. The proteome was then compared with that of JG-62, a tolerant genotype. Comparative proteomics revealed genotype-specific expression of many proteins involved in a variety of cellular functions. Further, the reversible and irreversible changes in the proteomes revealed their differing ability to recover from dehydration-induced damage. We propose that cell wall restructuring and superior homeostasis, particularly the management of reactive oxygen species, may render better dehydration-adaptation. To our knowledge, this is the first report on the comprehensive comparison of dehydration-responsive organellar proteome of two genotypes with contrasting tolerance. PMID:21348435

Bhushan, Deepti; Jaiswal, Dinesh Kumar; Ray, Doel; Basu, Debarati; Datta, Asis; Chakraborty, Subhra; Chakraborty, Niranjan

2011-04-01

379

Cosmic curvature and condensation  

NASA Technical Reports Server (NTRS)

It is shown that the universe may consist of a patchwork of domains with different Riemann curvature constants k = 0, +/-1. Features of a phase transition in which flat space breaks up in a transition 2k0 - k(-) + k(+) with initial scale factors R(-) = R(+) are postulated and explored. It is shown that such a transition is energetically permitted, has the equivalent of a Curie temperature, and can lead in a natural way to the formation of voids and galaxies. It is predicted that, if the ambient universe on average is well fitted by a purely k(-) space, with only occasional domains of k(+) containing galaxies, a density parameter of (A(z sub c + 1)) super -1 should be expected, where z sub c represents the redshift of the earliest objects to have condensed, and A takes on values ranging from about 5 to 3. Present observations of quasars would suggest a density of about 0.03 or 0.05, respectively, but it could be lower if earlier condensation took place.

Harwit, Martin

1992-01-01

380

Water Replacement Hypothesis in Atomic Detail—Factors Determining the Structure of Dehydrated Bilayer Stacks  

PubMed Central

Abstract According to the water replacement hypothesis, trehalose stabilizes dry membranes by preventing the decrease of spacing between membrane lipids under dehydration. In this study, we use molecular-dynamics simulations to investigate the influence of trehalose on the area per lipid (APL) and related structural properties of dehydrated bilayers in atomic detail. The starting conformation of a palmitoyloleolylphosphatidylcholine lipid bilayer in excess water was been obtained by self-assembly. A series of molecular-dynamics simulations of palmitoyloleolylphosphatidylcholine with different degrees of dehydration (28.5, 11.7, and 5.4 waters per lipid) and different molar trehalose/lipid ratios (<1:1, 1:1, and >1:1) were carried out in the NPT ensemble. Water removal causes the formation of multilamellar “stacks” through periodic boundary conditions. The headgroups reorient from pointing outward to inward with dehydration. This causes changes in the electrostatic interactions between interfaces, resulting in interface interpenetration. Interpenetration creates self-spacing of the bilayers and prevents gel-phase formation. At lower concentrations, trehalose does not separate the interfaces, and acting together with self-spacing, it causes a considerable increase of APL. APL decreases at higher trehalose concentrations when the layer of sugar physically separates the interfaces. When interfaces are separated, the model confirms the water replacement hypothesis. PMID:19619463

Golovina, Elena A.; Golovin, Andrey V.; Hoekstra, Folkert A.; Faller, Roland

2009-01-01

381

Influence of graded dehydration on hyperthermia and cardiovascular drift during exercise  

Microsoft Academic Search

respectively, during NF, SF, MF, and LF. After 2 h of exercise, esophageal temperature (T,,), HR, and SV were significantly different among the four trials (P < 0.05), with the exception of NF and SF. The magnitude of dehydration accrued after 2 h of exercise in the four trials was linearly related with the increase in T,, (r = 0.98,

SCOTT J. MONTAIN; EDWARD F. COYLE

382

Carbohydrates and the dehydration inactivation of Lactobacillus plantarum: The role of moisture distribution and water activity  

Microsoft Academic Search

Sucrose, maltose, lactose, trehalose, glucose, fructose and sorbitol were tested for their ability to minimize the dehydration inactivation of Lactobacillus plantarum during fluidized bed drying. Desorption isotherms were measured for starch and L. plantarum, for binary mixtures containing starch and a carbohydrate, and for ternary mixtures composed of L. plantarum, starch and a carbohydrate. The moisture distribution inside the drying

Leonie J. M. Linders; Gerard I. W. de Jong; Gerrit Meerdink; Klaas van't Riet

1997-01-01

383

Pervaporation process and use in treating waste stream from glycol dehydrator  

DOEpatents

Pervaporation processes and apparatus with few moving parts. Ideally, only one pump is used to provide essentially all of the motive power and driving force needed. The process is particularly useful for handling small streams with flow rates less than about 700 gpd. Specifically, the process can be used to treat waste streams from glycol dehydrator regeneration units.

Kaschemekat, Jurgen (Campbell, CA); Baker, Richard W. (Palo Alto, CA)

1994-01-01

384

Inactivation of Enterobacter sakazakii of dehydrated infant formula by gamma-irradiation  

NASA Astrophysics Data System (ADS)

Enterobacter sakazakii has been implicated as a causal organism in a severe form of neonatal meningitis, with reported mortality rates of 20%. The population at greatest risk is immunocompromised infants of any age. Dried infant formula has been identified as a potential source of the organism in both outbreaks and sporadic cases. The objective of this study was to investigate theirradiation effect of the inactivation on E. sakazakii (ATCC 29544) of a dehydrated infant formula. The D10-values were 0.22-0.27 and 0.76 kGy for broth and dehydrated infant formula, respectively. The irradiation at 5.0 kGy was able to completely eliminate the E. sakazakii inoculated at 8.0 to 9.0 log CFU g -1 onto a dehydrated infant formula. There was no regrowth for all samples during the time they were stored at 10 °C for 6 h after rehydration. The present results indicated that a gamma-irradiation could potentially be used to inactivate E. sakazakii in a dehydrated powdered infant formula.

Lee, Ju-Woon; Oh, Sang-Hee; Byun, Eui-Baek; Kim, Jae-Hun; Kim, Jang-Ho; Woon, Jae-Ho; Byun, Myung-Woo

2007-11-01

385

FEASIBILITY OF USING INFRARED HEATING FOR BLANCHING AND DEHYDRATION OF FRUITS AND VEGETABLES  

Technology Transfer Automated Retrieval System (TEKTRAN)

The objective of this study was to evaluate the feasibility of using medium and far infrared heating for blanching and dehydration of various fruits and vegetables. The infrared blanching was referred as infrared dry-blanching (IDB) in this study since no water or steam was used. A catalytic infra...

386

LOW-COST ZEOLITE MEMBRANE MODULES FOR SOLVENT DEHYDRATION - PHASE I  

EPA Science Inventory

A number of very high-volume liquid chemicals form azeotropes with water and can be dehydrated to required purity levels only through the use of entrainers or drying agents. The handling and disposal of these additional chemicals present significant environmental risk...

387

Ultrasound-Assisted Osmotic Dehydration of Strawberries: Effect of Pretreatment Time and Ultrasonic Frequency  

Microsoft Academic Search

Pretreatment of fruits prior to drying has shown success in reducing drying time and costs. In this work, ultrasound-assisted osmotic dehydration has been implemented as a method to increase water diffusivity and reduce drying time in strawberries. Strawberry halves were immersed in distilled water and in two different concentrations of sucrose solutions while pretreatment time and ultrasonic frequency levels were

Juan Garcia-Noguera; Francisca I. P. Oliveira; Maria Izabel Gallão; Curtis L. Weller; Sueli Rodrigues; Fabiano A. N. Fernandes

2010-01-01

388

Sec-mediated transport of posttranslationally dehydrated peptides in Lactococcus lactis.  

PubMed

Nisin is a lanthionine-containing antimicrobial peptide produced by Lactococcus lactis. Its (methyl)lanthionines are introduced by two posttranslational enzymatic steps involving the dehydratase NisB, which dehydrates serine and threonine residues, and the cyclase NisC, which couples these dehydrated residues to cysteines, yielding thioether-bridged amino acids called lanthionines. The prenisin is subsequently exported by the ABC transporter NisT and extracellularly processed by the peptidase NisP. L. lactis expressing the nisBTC genes can modify and secrete a wide range of nonlantibiotic peptides. Here we demonstrate that in the absence of NisT and NisC, the Sec pathway of L. lactis can be exploited for the secretion of dehydrated variants of therapeutic peptides. Furthermore, posttranslational modifications by NisB and NisC still occur even when the nisin leader is preceded by a Sec signal peptide or a Tat signal peptide 27 or 44 amino acids long, respectively. However, transport of fully modified prenisin via the Sec pathway is impaired. The extent of NisB-mediated dehydration could be improved by raising the intracellular concentration NisB or by modulating the export efficiency through altering the signal sequence. These data demonstrate that besides the traditional lantibiotic transporter NisT, the Sec pathway with an established broad substrate range can be utilized for the improved export of lantibiotic enzyme-modified (poly)peptides. PMID:17041158

Kuipers, Anneke; Wierenga, Jenny; Rink, Rick; Kluskens, Leon D; Driessen, Arnold J M; Kuipers, Oscar P; Moll, Gert N

2006-12-01

389

A Triple Iron Triathlon Leads to a Decrease in Total Body Mass but Not to Dehydration  

ERIC Educational Resources Information Center

A loss in total body mass during an ultraendurance performance is usually attributed to dehydration. We identified the changes in total body mass, fat mass, skeletal muscle mass, and selected markers of hydration status in 31 male nonprofessional ultratriathletes participating in a Triple Iron triathlon involving 11.4 km swimming, 540 km cycling…

Knechtle, Beat; Knechtle, Patrizia; Rosemann, Thomas; Oliver, Senn

2010-01-01

390

Removal of Sea Salt Hydrate Water from Seawater-Derived Samples by Dehydration  

E-print Network

Removal of Sea Salt Hydrate Water from Seawater-Derived Samples by Dehydration Amanda A. Frossard of natural seawater contain both sea salts and organic components. Depending on the temperature, pressure, and speed of drying, the salt components can form hydrates that bind water, slowing evaporation of the water

Russell, Lynn

391

Evaluation of Dehydrated Restaurant Food Waste Products as Feedstuffs for Finishing Pigs1,2  

Microsoft Academic Search

Two dehydrated restaurant food waste (DFW) products were evaluated as potential feedstuffs for finishing pigs. For each product, fresh food wastes were obtained from food service operations at a resort complex in central Florida. The wastes were mostly leftover food and plate scrapings. The wastes were minced, blended with a feed stock (soy hulls and wheat flour (DFW1) or soy

R. O. Myer; J. H. Brendemuhl; D. D. Johnson

392

Coupling gas chromatography and electronic nose for dehydration and desalcoholization of alcoholized beverages  

Microsoft Academic Search

Aroma characterization of alcoholic beverages with sensor array electronic noses is a difficult challenge due to the masking effect of ethanol. Back-flush gas chromatography is proposed as a novel tool for the pretreatment of vapour samples before analysis in the electronic nose. The dehydration and desalcoholization step can be conducted in parallel with electronic nose detection, reducing significantly the analysis

J. A. Ragazzo-Sanchez; P. Chalier; C. Ghommidh

2005-01-01

393

Effect of Pulsed Electric Field Pre-Treatment on Osmotic Dehydration of Strawberries  

Technology Transfer Automated Retrieval System (TEKTRAN)

The objective of this research was to study the effect of pulsed electric fields (PEF) as a pre-treatment on osmotic dehydration characteristics and quality of strawberries. The studied PDF treatment conditions included three strengths of electric field (1.0, 2.0, 3.0 Kw/cm) and three numbers of pu...

394

Spectroscopic study of the dehydration and/or dehydroxylation of phyllosilicate and zeolite minerals  

E-print Network

Spectroscopic study of the dehydration and/or dehydroxylation of phyllosilicate and zeolite, and chlorite) and two natural zeolites are reported here. Pressed powders of sizeseparated phyllosilicate and natural zeolite samples were heated incrementally from 100°C to 900°C, cooled to room temperature

Glotch, Timothy D.

395

Optimization of osmotic dehydration of papaya followed by air-drying  

Microsoft Academic Search

Papayas are a fragile fruit; characteristic that limits large-scale exportation from the producing centers to countries in temperate regions. Loss of fruit ranges from 10% to 40% and could be reduced if papayas were dried. The process of osmotic dehydration followed by air-drying was studied and modeled for papaya preservation, so it could be optimized. The developed model has been

Fabiano A. N. Fernandes; Sueli Rodrigues; Odisséia C. P. Gaspareto; Edson L. Oliveira

2006-01-01

396

Dehydration Hardly Slows Hopping Toads (Rhinella granulosa) from Xeric and Mesic Environments  

E-print Network

451 Dehydration Hardly Slows Hopping Toads (Rhinella granulosa) from Xeric and Mesic Environments the effects of temperature and hydration on the hopping speeds of Rhinella granulosa, a small toad from interact to determine performance and whether toads from the Caatinga differ from their conspecifics from

Angilletta, Michael

397

Recent development in osmotic dehydration of fruit and vegetables: a review.  

PubMed

Osmotic dehydration of fruits and vegetables is achieved by placing the solid/semi solid, whole or in pieces, in a hypertonic solution (sugar and/or salt) with a simultaneous counter diffusion of solutes from the osmotic solution into the tissues. Osmotic dehydration is recommended as a processing method to obtain better quality of food products. Partial dehydration allows structural, nutritional, sensory, and other functional properties of the raw material to be modified. However, the food industry uptake of osmotic dehydration of foods has not been extensive as expected due to the poor understanding of the counter current flow phenomena associated with it. However, these flows are in a dynamic equilibrium with each other and significantly influence the final product in terms of preservation, nutrition, and organoleptic properties. The demand of healthy, natural, nutritious, and tasty processed food products continuously increases, not only for finished products, but also for ingredient to be included in complex foods such as ice cream, cereals, dairy, confectionaries, and bakery products. PMID:24915357

Chandra, Suresh; Kumari, Durvesh

2015-01-01

398

Hydrogen Bonding between Sugar and Protein Is Responsible for Inhibition of Dehydration-Induced Protein Unfolding  

Microsoft Academic Search

The nature of the interaction responsible for the inhibition of protein unfolding and subsequent damage by sugars during dehydration is unclear. The relationship between sample moisture content measured by coulometric Karl Fischer titration and the apparent moisture content predicted by the area of the protein side chain carboxylate band at approximately 1580 cm?1in infrared spectra of dried protein–sugar samples was

S. Dean Allison; Byeong Chang; Theodore W. Randolph; John F. Carpenter

1999-01-01

399

Newly developed ceramic membranes for dehydration and separation of organic mixtures by pervaporation  

Microsoft Academic Search

Polymeric pervaporation membranes sometimes show great variety in performance when they are alternately used for different solvent mixtures. In addition, membrane stability in time is a problem in case of some solvents. Therefore, newly developed ceramic silica membranes with a “dense” top layer were tested for pervaporation. In dehydration of the lower alcohols methanol, ethanol and 2-propanol selectivities of 400,

Robert W. van Gemert; F. Petrus Cuperus

1995-01-01

400

Effect of Gamma Irradiation on Hygienic Quality and Chemical Characteristics of Dehydrated Ostrich Eggs  

Microsoft Academic Search

Role of gamma irradiation on improving hygienic quality of dehydrated Ostrich eggs during cold storage was studied. Irradiation with dose level 6 kGy proved to be quite tool to keep quality of ostrich egg components since it decreased their bacterial counts less than 100 cells\\/g either after irradiation process or during cold storage for 6 months. Total coliform, E. coli

H. M. SWAILAM; A. A. ABOU ZEID

401

Neonatal hypernatremic dehydration associated with breast-feeding malnutrition: a retrospective survey  

PubMed Central

BACKGROUND: Hypernatremic dehydration in neonates is a potentially devastating condition. Recent reports have identified breast-feeding malnutrition as a key factor in its pathophysiology. METHODS: Using a theoretical framework for breast-feeding kinetics, a retrospective chart review of all neonates less than 28 days of age who were seen at either British Columbia's Children's Hospital or the Vancouver Breastfeeding Centre between 1991-1994 was conducted to identify and classify possible causes of breast-feeding malnutrition among neonates who developed hypernatremic dehydration. RESULTS: Twenty-one cases hypernatremic dehydration were identified. Infant weight loss ranged from 8% to 30% of birth weight, and serum sodium levels ranged from 146 mmol/L to 207 mmol/L. In each case, maternal or infant factors (e.g., poor breast-feeding technique, lactation failure following postpartum hemorrhage and infant suckling disorders associated with cleft palate or ankyloglossia) that could interfere with either lactation or breast-feeding dynamics and account for insufficient breast milk intake were identified. INTERPRETATION: Prenatal and in-hospital screening for maternal and infant risk factors for breast-feeding malnutrition combined with early postpartum follow-up to detect excessive infant weight loss are important for the prevention of neonatal hypernatremic dehydration. PMID:10738450

Livingstone, V H; Willis, C E; Abdel-Wareth, L O; Thiessen, P; Lockitch, G

2000-01-01

402

Some thermal properties of fresh and osmotically dehydrated Kiwifruit above and below the initial freezing temperature  

Microsoft Academic Search

Thermal properties of fresh and osmotically dehydrated Kiwifruit were experimentally measured. Enthalpy and heat capacity, in the range from ?40°C to 40°C, and initial freezing temperature were determined by DSC. Density was measured by picnometry in the range between ?70°C and 30°C. Prediction equations from the literature for enthalpy, heat capacity and density as a function of temperature, for different

Ana M. Tocci; Rodolfo H. Mascheroni

2008-01-01

403

Food freezing with simultaneous surface dehydration: approximate prediction of freezing time  

Microsoft Academic Search

Freezing of unpackaged foods induces mass transfer in the form of surface ice sublimation, which in turn modifies heat transfer conditions. At present there are no simplified methods for predicting freezing times when surface dehydration occurs. This paper uses a previously developed model for the simulation of simultaneous heat and mass transfer during food freezing and storage to generate a

Laura A. Campañone; Viviana O. Salvadori; Rodolfo H. Mascheroni

2005-01-01

404

EFFECTS OF DIETARY INCLUSION OF DEHYDRATED LUCERNE AND WHOLE LINSEED ON RABBIT MEAT QUALITY  

Microsoft Academic Search

The effect of dietary use of dehydrated lucerne meal (DLM) and whole linseed (LIN) on chemical- physical traits, fatty acid composition, susceptibility to lipid oxidation, and sensory quality of rabbit meat and meat products (hamburgers) was studied. Two groups of 128 weaned rabbits (37 d-old) were fed on diets containing 25 or 35% DLM. At 64 d of age, the

405

Polymeric blend nanocomposite membranes for ethanol dehydration-effect of morphology and membrane-solvent interactions  

EPA Science Inventory

Nanocomposite membranes (NCMs) of sodium alginate/poly(vinyl pyrrolidone) blend polymers incorporated with varying concentrations of phosphotungstic acid (H3PW12O40) (PWA) nanoparticles have been prepared and used in ethanol dehydration by the pervaporation (PV) technique. Effe...

406

Dehydration Kinetics of Pharmaceutical Hydrate: Effects of Environmental Conditions and Crystal Forms  

Microsoft Academic Search

The present study was conducted to investigate the influence of drying condition (atmospheric pressure with varying temperature, acetone vapor-induced environment, and vacuum pressure) on the dehydration kinetics of carbamazepine dihydrate. Samples were prepared in loose crystals and agglomerated forms. Increasing driving forces, that is, higher temperature (up to 60°C), low vacuum pressure (10 Torr), and the presence of acetone vapor pressure

Ji Yi Khoo; Daryl R. Williams; Jerry Y. Y. Heng

2010-01-01

407

Mass transfer during osmotic dehydration of banana: Fickian diffusion in cylindrical configuration  

Microsoft Academic Search

Mass transfer during osmotic dehydration of banana has been studied. The solution of Fick's law for unsteady state mass transfer in cylindrical configuration has been used to calculate the effective diffusion coefficients over a range of temperature (25–35 °C) and concentration (40–70 °B) of osmotic solution. The effective diffusion coefficient has been empirically correlated with the concentration and temperature of

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

1997-01-01

408

INFLUENCE OF OSMOTIC DEHYDRATION ON TEXTURE AND PECTIC COMPOSITION OF KIWIFRUIT SLICES  

Microsoft Academic Search

In order to optimize the osmotic dehydration process as a pre-treatment to freezing, chemical and structural characteristics of the raw fruit have to be studied together with their influence on the solid liquid exchanges and on the quality of the end productsTextural properties of fruits are intimately associated with the cellular structure and pectic composition. So the influence of osmodehydration

D. Torreggiani; E. Forni; A. Maestrelli; F. Quadri

1999-01-01

409

Onset, extent, and duration of dehydration in the Southern Hemisphere polar vortex  

Microsoft Academic Search

Satellite observations of water vapor and aerosol extinction along with temperature trajectory calculations are analyzed for the Southern Hemisphere winter of 1992 in order to determine the onset, extent, and duration of dehydration within the polar vortex. Our investigation uses measurements of water vapor from the Microwave Limb Sounder (MLS) and aerosol extinction from the Cryogenic Limb Array Etalon Spectrometer

Elizabeth M. Stone; Azadeh Tabazadeh; Eric Jensen; Hugh C. Pumphrey; Michelle L. Santee; John L. Mergenthaler

2001-01-01

410

Alpha-particle condensation in excited 12C  

E-print Network

The fragmentation of quasi-projectiles from the nuclear reaction $^{40}Ca$+$^{12}C$ at 25 MeV/nucleon was used to produce excited states candidates to $\\alpha$-particle condensation. The methodology relies on high granularity 4$\\pi$ detection coupled to correlation function techniques. Under the assumption that the equality among the kinetic energies of the emitted $\\alpha$-particles and the emission simultaneity constitutes a reliable fingerprint of $\\alpha$ condensation, we identify several tens of events corresponding to the deexcitation of the Hoyle state of $^{12}$C which fulfill the condition.

Ad. R. Raduta; B. Borderie; E. Geraci; N. Le Neindre; P. Napolitani; M. F. Rivet; R. Alba; F. Amorini; G. Cardella; M. Chatterjee; E. De Filippo; D. Guinet; P. Lautesse; E. La Guidara; G. Lanzalone; G. Lanzano; I. Lombardo; O. Lopez; C. Maiolino; A. Pagano; S. Pirrone; G. Politi; F. Porto; F. Rizzo; P. Russotto; J. P. Wieleczko

2010-04-19

411

Effects of dehydration and blockade of angiotensin II AT1 receptor on stress hormones and anti-oxidants in the one-humped camel  

PubMed Central

Background The objective of this study was to provide for the first time data on plasma catecholamines, cortisol, glutathione and malondialdehyde after long term dehydration (20 days) in the presence and absence of angiotensin II (Ang II) AT1 receptor blocker (losartan) versus levels in time-matched, non-dehydrated control camels and to record the responses of glutathione and malondialdehyde activity in liver and kidney homogenates in control, dehydrated-losartan treated and dehydrated camels. Eighteen male camels were studied, six hydrated (control group), six dehydrated and treated with losartan (treated group) and six dehydrated not treated (dehydrated). Results Plasma levels of norepinephrine and dopamine were significantly increased (P?dehydrated groups compared to time matched control, whereas Plasma epinephrine level showed significant decrease (P?dehydrated groups compared to control. Plasma cortisol also showed significant increase (P?dehydrated groups compared to control. Glutathione levels in plasma, liver and kidney homogenates for both treated and dehydrated groups reveled significant increase (P?dehydrated groups. Conclusion In conclusion, the results of this study demonstrated that dehydration substantially increased the circulating levels of norepinephrine, dopamine and cortisol but decreased plasma epinephrine. Similarly, losartan showed similar effects to that of dehydration. In addition, this investigation showed dehydration alone or in combination with losartan induced significant increments in glutathione and malondialdehyde activities in plasma, liver and kidney homogenates, presumably in order to counteract the potentially damaging effects of free radicals. Blockade of angiotensin II AT1 receptors did not alter significantly the response of dehydration in any of these indices. PMID:24252635

2013-01-01

412

Dehydration stress memory genes of Zea mays; comparison with Arabidopsis thaliana  

PubMed Central

Background Pre-exposing plants to diverse abiotic stresses may alter their physiological and transcriptional responses to a subsequent stress, suggesting a form of “stress memory”. Arabidopsis thaliana plants that have experienced multiple exposures to dehydration stress display transcriptional behavior suggesting “memory” from an earlier stress. Genes that respond to a first stress by up-regulating or down-regulating their transcription but in a subsequent stress provide a significantly different response define the ‘memory genes’ category. Genes responding similarly to each stress form the ‘non-memory’ category. It is unknown whether such memory responses exists in other Angiosperm lineages and whether memory is an evolutionarily conserved response to repeated dehydration stresses. Results Here, we determine the transcriptional responses of maize (Zea mays L.) plants that have experienced repeated exposures to dehydration stress in comparison with plants encountering the stress for the first time. Four distinct transcription memory response patterns similar to those displayed by A. thaliana were revealed. The most important contribution is the evidence that monocot and eudicot plants, two lineages that have diverged 140 to 200 M years ago, display similar abilities to ‘remember’ a dehydration stress and to modify their transcriptional responses, accordingly. The highly sensitive RNA-Seq analyses allowed to identify genes that function similarly in the two lineages, as well as genes that function in species-specific ways. Memory transcription patterns indicate that the transcriptional behavior of responding genes under repeated stresses is different from the behavior during an initial dehydration stress, suggesting that stress memory is a complex phenotype resulting from coordinated responses of multiple signaling pathways. Conclusions Structurally related genes displaying the same memory responses in the two species would suggest conservation of the genes’ memory during the evolution of plants’ dehydration stress response systems. On the other hand, divergent transcription memory responses by genes encoding similar functions would suggest occurrence of species-specific memory responses. The results provide novel insights into our current knowledge of how plants respond to multiple dehydration stresses, as compared to a single exposure, and may serve as a reference platform to study the functions of memory genes in adaptive responses to water deficit in monocot and eudicot plants. PMID:24885787

2014-01-01

413

Four distinct types of dehydration stress memory genes in Arabidopsis thaliana  

PubMed Central

Background How plants respond to dehydration stress has been extensively researched. However, how plants respond to multiple consecutive stresses is virtually unknown. Pre-exposure to various abiotic stresses (including dehydration) may alter plants’ subsequent responses by improving resistance to future exposures. These observations have led to the concept of ‘stress memory’ implying that during subsequent exposures plants provide responses that are different from those during their first encounter with the stress. Genes that provide altered responses in a subsequent stress define the ‘memory genes’ category; genes responding similarly to each stress form the ‘non-memory’ category. Results Using a genome-wide RNA-Seq approach we determine the transcriptional responses of Arabidopsis plants that have experienced multiple exposures to dehydration stress and compare them with the transcriptional behavior of plants encountering the stress for the first time. The major contribution of this study is the revealed existence of four distinct, previously unknown, transcription memory response patterns of dehydration stress genes in A.thaliana. The biological relevance for each of the four memory types is considered in the context of four overlapping strategies employed by a plant to improve its stress tolerance and/or survival: 1) increased synthesis of protective, damage-repairing, and detoxifying functions; 2) coordinating photosynthesis and growth under repetitive stress; 3) re-adjusting osmotic and ionic equilibrium to maintain homeostasis; and 4) re-adjusting interactions between dehydration and other stress/hormone regulated pathways. Conclusions The results reveal the unknown, hitherto, existence of four distinct transcription memory response types in a plant and provide genome-wide characterization of memory and non-memory dehydration stress response genes in A.thaliana. The transcriptional responses during repeated exposures to stress are different from known responses occurring during a single exposure. GO analyses of encoded proteins suggested implications for the cellular/organismal protective, adaptive, and survival functions encoded by the memory genes. The results add a new dimension to our understanding of plants’ responses to dehydration stress and to current models for interactions between different signaling systems when adjusting to repeated spells of water deficits. PMID:24377444

2013-01-01

414

Cavitation in dehydrating xylem of Picea abies: energy properties of ultrasonic emissions reflect tracheid dimensions  

PubMed Central

Ultrasonic emission (UE) testing is used to analyse the vulnerability of xylem to embolism, but the number of UEs often does not sufficiently reflect effects on hydraulic conductivity. We monitored the absolute energy of UE signals in dehydrating xylem samples hypothesizing that (i) conduit diameter is correlated with UE energy and (ii) monitoring of UE energy may enhance the utility of this technique for analysis of xylem vulnerability. Split xylem samples were prepared from trunk wood of Picea abies, and four categories of samples, derived from mature (I: earlywood, II: 30–50% latewood, III: >50% latewood) or juvenile wood (IV: earlywood) were used. Ultrasonic emissions during dehydration were registered and anatomical parameters (tracheid lumen area, number per area) were analysed from cross-sections. Attenuation of UE energy was measured on a dehydrating wood beam by repeated lead breaks. Vulnerability to drought-induced embolism was analysed on dehydrating branches by hydraulic, UE number or UE energy measurements. In split samples, the cumulative number of UEs increased linearly with the number of tracheids per cross-section, and UE energy was positively correlated with the mean lumen area. Ultrasonic emission energies of earlywood samples (I and IV), which showed normally distributed tracheid lumen areas, increased during dehydration, whereas samples with latewood (II and III) exhibited a right-skewed distribution of lumina and UE energies. Ultrasonic emission energy was hardly influenced by moisture content until ~40% moisture loss, and decreased exponentially thereafter. Dehydrating branches showed a 50% loss of conductivity at ?3.6 MPa in hydraulic measurements and at ?3.9 and ?3.5 MPa in UE analysis based on cumulative number or energy of signals, respectively. Ultrasonic emission energy emitted by cavitating conduits is determined by the xylem water potential and by the size of element. Energy patterns during dehydration are thus influenced by the vulnerability to cavitation, conduit size distribution as well as attenuation properties. Measurements of UE energy may be used as an alternative to the number of UEs in vulnerability analysis. PMID:21389002

Mayr, Stefan; Rosner, Sabine

2011-01-01

415

Magnets & Magnet Condensed Matter Science  

E-print Network

in Graphene on Boron Nitride 12 Magneto-elastic Coupling in Magnetically Frustrated Co3V2O8 13 FieldMagnets & Magnet Materials PAGE 29 Chemistry PAGE 35 Condensed Matter Science PAGE 6 Volume 18 No 18 No. 1 CONDENSED MATTER SCIENCE Technique development, graphene, magnetism & magnetic materials

McQuade, D. Tyler

416

Acute Peritoneal Dialysis in Neonates with Acute Kidney Injury and Hypernatremic Dehydration  

PubMed Central

? Objective: We aimed to evaluate the efficacy of acute peritoneal dialysis (PD) and clinical outcomes in neonates with acute kidney injury (AKI) and hypernatremic dehydration. ? Methods: The medical records of 15 neonates with AKI and hypernatremic dehydration who were treated with acute PD were reviewed. The diagnoses were AKI with hypernatremic dehydration with or without sepsis in 13 patients and AKI with hypernatremia and congenital nephropathy in 2 patients. The main indications for PD were AKI with some combination of oligoanuria, azotemia, hyperuricemia, and metabolic acidosis unresponsive to initial intensive medical treatment. ? Results: The mean age of the patients at dialysis initiation was 11.9 ± 9 days, and the mean duration of PD was 6.36 ± 4.8 days. In 7 patients (46.7%), hypotension required the use of vasopressors, and in 6 patients (40%), mechanical ventilation was required. Peritoneal dialysis-related complications occurred in 7 patients (46.7%), the most common being catheter malfunction (n = 6). Four episodes of peritonitis occurred in the 15 patients (26.7%), 2 episodes in patients with congenital renal disease and 2 episodes in patients with sepsis and multiorgan failure, who did not survive. Congenital renal disease, septicemia, and the need for mechanical ventilation were important factors influencing patient survival. All patients with no pre-existing renal disease or sepsis recovered their renal function and survived. ? Conclusions: In neonates with AKI and hypernatremic dehydration, PD is safe and successful, and in patients without congenital renal disease or sepsis, the prognosis is good. Peritoneal dialysis should be the treatment of choice in neonates with AKI and hypernatremic dehydration who do not respond to appropriate med ical treatment. PMID:23123669

Yildiz, Nurdan; Erguven, Müferet; Yildiz, Metin; Ozdogan, Tutku; Turhan, Pinar

2013-01-01

417

Leaf Shrinkage with Dehydration: Coordination with Hydraulic Vulnerability and Drought Tolerance1[C][W][OPEN  

PubMed Central

Leaf shrinkage with dehydration has attracted attention for over 100 years, especially as it becomes visibly extreme during drought. However, little has been known of its correlation with physiology. Computer simulations of the leaf hydraulic system showed that a reduction of hydraulic conductance of the mesophyll pathways outside the xylem would cause a strong decline of leaf hydraulic conductance (Kleaf). For 14 diverse species, we tested the hypothesis that shrinkage during dehydration (i.e. in whole leaf, cell and airspace thickness, and leaf area) is associated with reduction in Kleaf at declining leaf water potential (?leaf). We tested hypotheses for the linkage of leaf shrinkage with structural and physiological water relations parameters, including modulus of elasticity, osmotic pressure at full turgor, turgor loss point (TLP), and cuticular conductance. Species originating from moist habitats showed substantial shrinkage during dehydration before reaching TLP, in contrast with species originating from dry habitats. Across species, the decline of Kleaf with mild dehydration (i.e. the initial slope of the Kleaf versus ?leaf curve) correlated with the decline of leaf thickness (the slope of the leaf thickness versus ?leaf curve), as expected based on predictions from computer simulations. Leaf thickness shrinkage before TLP correlated across species with lower modulus of elasticity and with less negative osmotic pressure at full turgor, as did leaf area shrinkage between full turgor and oven desiccation. These findings point to a role for leaf shrinkage in hydraulic decline during mild dehydration, with potential impacts on drought adaptation for cells and leaves, influencing plant ecological distributions. PMID:24306532

Scoffoni, Christine; Vuong, Christine; Diep, Steven; Cochard, Hervé; Sack, Lawren

2014-01-01

418

Dietary influences on the hydration and acid-base status of experimentally dehydrated dairy calves.  

PubMed

The incorporation of oral rehydration solutions (ORS) into 'milk meals' is potentially an effective, time-saving method of treating diarrhoeic calves. Although milk-based ORS are effective in improving the hydration and acid-base status of healthy calves, this effect remains to be confirmed in dehydrated/diarrhoeic animals. In this study, six experimentally-dehydrated calves were fed with either milk replacer (MR) or an ORS prepared in either water (WORS) or MR (MORS). In one experiment, calves were not treated and blood samples were taken before and after feeding. Parameters of hydration status were determined and blood gas analysis was performed. Plasma volumes increased significantly following the intake of a 'fluid meal' whereas they remained constant in the absence of treatment. The rate of plasma volume expansion was reduced by the feeding of MR relative to WORS or MORS. In dehydrated calves, the expansion of plasma volume was more pronounced following the intake of WORS but the increase was less and plasma osmolality increased significantly following the ingestion of MORS. The acid-base status of animals improved as a result of fluid absorption, but this effect was less obvious as the experimental protocol resulted in severe dehydration and moderate acidosis. Feeding hypertonic MORS raised the plasma osmolality in dehydrated calves, and may increase the risk of hypernatraemia in diarrhoeic calves, which should therefore have ad libitum access to water when undergoing treatment with hypertonic ORS. Further research is planned to assess whether feeding ORS reconstituted in milk or MR combined with ad libitum access to water offers a practical treatment for diarrhoeic calves. PMID:24342525

Kirchner, D; Schwedhelm, L; Coenen, M; Bachmann, L

2014-02-01

419

Hydrogen peroxide and ecdysone in the cryoprotective dehydration strategy of Megaphorura arctica (Onychiuridae: Collembola).  

PubMed

The Arctic springtail, Megaphorura arctica, survives sub-zero temperatures in a dehydrated state via trehalose-dependent cryoprotective dehydration. Regulation of trehalose biosynthesis is complex; based in part on studies in yeast and fungi, its connection with oxidative stress caused by exposure of cells to oxidants, such as hydrogen peroxide (H?O?), or dehydration, is well documented. In this respect, we measured the amount of H?O? and antioxidant enzyme activities (superoxide dismutases: copper, zinc--CuZnSOD and manganese containing--MnSOD, and catalase--CAT), as the regulatory components determining H?O? concentrations, in Arctic springtails incubated at 5 °C (control) versus -2 °C (threshold temperature for trehalose biosynthesis). Because ecdysone also stimulates trehalose production in insects and regulates the expression of genes involved in redox homeostasis and antioxidant protection in Drosophila, we measured the levels of the active physiological form of ecdysone--20-hydroxyecdysone (20-HE). Significantly elevated H?O? and 20-HE levels were observed in M. arctica incubated at -2 °C, supporting a link between ecdysone, H?O?, and trehalose levels during cryoprotective dehydration. CAT activity was found to be significantly lower in M. arctica incubated at -2 °C versus 5 °C, suggesting reduced H?O? breakdown. Furthermore, measurement of the free radical composition in Arctic springtails incubated at 5 °C (controls) versus -2 °C by Electron Paramagnetic Resonance spectroscopy revealed melanin-derived free radicals at -2 °C, perhaps an additional source of H?O?. Our results suggest that H?O? and ecdysone play important roles in the cryoprotective dehydration process in M. arctica, linked with the regulation of trehalose biosynthesis. PMID:23143920

Grubor-Lajši?, Gordana; Petri, Edward T; Koji?, Danijela; Pura?, Jelena; Popovi?, Zeljko D; Worland, Roger M; Clark, Melody S; Mojovi?, Miloš; Blagojevi?, Duško P

2013-02-01

420

Troubleshooting surface condenser venting systems  

SciTech Connect

In an ideal situation, the condensing pressure achievable in a steam surface condenser is determined by the exiting cooling water temperature. However, the failure of the venting system to properly remove noncondensible gases from the steam condenser will result in elevated condenser pressures. Information is presented in this paper relative to the most common venting systems available, as well as providing procedures for troubleshooting each type of system. A description is given of the various operating characteristics, along with narrative discussions of field problems and experiences. Simple visual, audible and physical guides to the analysis of venting system problems are discussed. Power plant operating personnel will be able to utilize this information when investigating steam condenser performance problems. A check list is provided which can be used to isolate these performance problems. 4 figs., 3 tabs.

Lines, J.R.; Athey, R.E.; Frens, L.L. [Graham Manufacturing Company, Batavia, NY (United States)

1996-08-01

421

Microgravity condensing heat exchanger  

NASA Technical Reports Server (NTRS)

A heat exchanger having a plurality of heat exchanging aluminum fins with hydrophilic condensing surfaces which are stacked and clamped between two cold plates. The cold plates are aligned radially along a plane extending through the axis of a cylindrical duct and hold the stacked and clamped portions of the heat exchanging fins along the axis of the cylindrical duct. The fins extend outwardly from the clamped portions along approximately radial planes. The spacing between fins is symmetric about the cold plates, and are somewhat more closely spaced as the angle they make with the cold plates approaches 90.degree.. Passageways extend through the fins between vertex spaces which provide capillary storage and communicate with passageways formed in the stacked and clamped portions of the fins, which communicate with water drains connected to a pump externally to the duct. Water with no entrained air is drawn from the capillary spaces.

Thomas, Christopher M. (Inventor); Ma, Yonghui (Inventor); North, Andrew (Inventor); Weislogel, Mark M. (Inventor)

2011-01-01

422

Method of performing sugar dehydration and catalyst treatment  

DOEpatents

The invention includes a method of treating a solid acid catalyst. After exposing the catalyst to a mixture containing a sugar alcohol, the catalyst is washed with an organic solvent and is then exposed to a second reaction mixture. The invention includes a process for production of anhydrosugar alcohol. A solid acid catalyst is provided to convert sugar alcohol in a first sample to an anhydrosugar alcohol. The catalyst is then washed with an organic solvent and is subsequently utilized to expose a second sample. The invention includes a method for selective production of an anhydrosugar. A solid acid catalyst is provided within a reactor and anhydrosugar alcohol is formed by flowing a starting sugar alcohol into the reactor. The acid catalyst is then exposed to an organic solvent which allows a greater amount of additional anhydrosugar to be produced than would occur without exposing the acid catalyst to the organic solvent.

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

2010-06-01

423

Reactions Between Water Soluble Organic Acids and Nitrates in Atmospheric Aerosols: Recycling of Nitric Acid and Formation of Organic Salts  

SciTech Connect

Atmospheric particles often include a complex mixture of nitrate and secondary organic materials accumulated within the same individual particles. Nitrate as an important inorganic component can be chemically formed in the atmosphere. For instance, formation of sodium nitrate (NaNO3) and calcium nitrate Ca(NO3)2 when nitrogen oxide and nitric acid (HNO3) species react with sea salt and calcite, respectively. Organic acids contribute a significant fraction of photochemically formed secondary organics that can condense on the preexisting nitrate-containing particles. Here, we present a systematic microanalysis study on chemical composition of laboratory generated particles composed of water soluble organic acids and nitrates (i.e. NaNO3 and Ca(NO3)2) investigated using computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and Fourier transform infrared micro-spectroscopy (micro-FTIR). The results show that water-soluble organic acids can react with nitrates releasing gaseous HNO3 during dehydration process. These reactions are attributed to acid displacement of nitrate with weak organic acids driven by the evaporation of HNO3 into gas phase due to its relatively high volatility. The reactions result in significant nitrate depletion and formation of organic salts in mixed organic acids/nitrate particles that in turn may affect their physical and chemical properties relevant to atmospheric environment and climate. Airborne nitrate concentrations are estimated by thermodynamic calculations corresponding to various nitrate depletions in selected organic acids of atmospheric relevance. The results indicate a potential mechanism of HNO3 recycling, which may further affect concentrations of gas- and aerosol-phase species in the atmosphere and the heterogeneous reaction chemistry between them.

Wang, Bingbing; Laskin, Alexander

2014-03-25

424

Condensation of amino acids to form peptides in aqueous solution induced by the oxidation of sulfur(iv): An oxidative model for prebiotic peptide formation  

Microsoft Academic Search

Condensation of amino acids to peptides is an important step during the origin of life. However, up to now, successful explanations\\u000a for plausible prebiotic peptide formation pathways have been limited. Here we report that the oxidation of sulfur (IV) can\\u000a induce the condensation reaction of carboxylic acids and amines to form amides, and the condensation reaction of amino acids\\u000a to

Fei Chen; Dan Yang

2007-01-01

425

Synthesis of fully substituted iminolactones via a three-component condensation of isocyanides and acetylenic esters with 2-bromo-1-(4-bromophenyl)ethanone  

Microsoft Academic Search

A novel three-component condensation reaction between an isocyanide, an electron-deficient acetylenic ester, and 2-bromo-1-(4-bromophenyl)?ethanone\\u000a efficiently provides fully substituted iminolactones in a one-pot condensation reaction without any activation or modification\\u000a in high yields.

Ahmad Shaabani; Ebrohim Soleimani; Afshin Sarvary

2008-01-01

426

Condensation of anhydrides or dicarboxylic acids with compounds containing active methylene groups. Part 19: Condensation of phthalic and substituted phthalic anhydrides with benzoylacetic ester  

NASA Technical Reports Server (NTRS)

Phthalylbenzoylacetic ester and its nitro and halogen derivatives were prepared through condensation of phthalic anhydride, nitrophthalic anhydride, and phthalic halide anhydride with benzoylacetic ester in a solution of acetic anhydride and triethylamine. The condensation of hemipinic acid anhydride proceeds similarly, but under more drastic conditions. Derivatives of indan-1,3-dione are also formed, with a small yield, in the reaction of nitrophthalic anhydrides with benzoylacetic ester in the presence of increased quantities of triethylamine.

Rotberg, Y. T.; Oshkaya, V. P.

1985-01-01

427

Condensation on Superhydrophobic Copper Oxide Nanostructures  

E-print Network

Condensation is an important process in both emerging and traditional power generation and water desalination technologies. Superhydrophobic nanostructures promise enhanced condensation heat transfer by reducing the ...

Enright, Ryan

428

Condensation on superhydrophobic copper oxide nanostructures .  

E-print Network

??Condensation is an important process in many power generation and water desalination technologies. Superhydrophobic nanostructured surfaces have unique condensation properties that may enhance heat transfer… (more)

Dou, Nicholas (Nicholas Gang)

2012-01-01

429

Insights into the Mechanism of Type I Dehydroquinate Dehydratases from Structures of Reaction Intermediates  

SciTech Connect

The biosynthetic shikimate pathway consists of seven enzymes that catalyze sequential reactions to generate chorismate, a critical branch point in the synthesis of the aromatic amino acids. The third enzyme in the pathway, dehydroquinate dehydratase (DHQD), catalyzes the dehydration of 3-dehydroquinate to 3-dehydroshikimate. We present three crystal structures of the type I DHQD from the intestinal pathogens Clostridium difficile and Salmonella enterica. Structures of the enzyme with substrate and covalent pre- and post-dehydration reaction intermediates provide snapshots of successive steps along the type I DHQD-catalyzed reaction coordinate. These structures reveal that the position of the substrate within the active site does not appreciably change upon Schiff base formation. The intermediate state structures reveal a reaction state-dependent behavior of His-143 in which the residue adopts a conformation proximal to the site of catalytic dehydration only when the leaving group is present. We speculate that His-143 is likely to assume differing catalytic roles in each of its observed conformations. One conformation of His-143 positions the residue for the formation/hydrolysis of the covalent Schiff base intermediates, whereas the other conformation positions the residue for a role in the catalytic dehydration event. The fact that the shikimate pathway is absent from humans makes the enzymes of the pathway potential targets for the development of non-toxic antimicrobials. The structures and mechanistic insight presented here may inform the design of type I DHQD enzyme inhibitors.

Light, Samuel H.; Minasov, George; Shuvalova, Ludmilla; Duban, Mark-Eugene; Caffrey, Michael; Anderson, Wayne F.; Lavie, Arnon (NWU); (UIC)

2012-02-27

430

Unfolding Reactions.  

ERIC Educational Resources Information Center

Describes how students use paper-strip molecules in hands-on activities to show the synthesis of larger organic molecules from smaller molecules. Focuses initially on condensation molecules involving the functional groups in alcohol and carboxylic acids. (DDR)

Streitberger, H. Eric

1997-01-01

431

Photochemical activity of Titan's low-altitude condensed haze.  

PubMed

Titan, the largest moon of Saturn and similar to Earth in many aspects, has unique orange-yellow colour that comes from its atmospheric haze, whose formation and dynamics are far from well understood. Present models assume that Titan's tholin-like haze formation occurs high in atmosphere through gas-phase chemical reactions initiated by high-energy solar radiation. Here we address an important question: Is the lower atmosphere of Titan photochemically active or inert? We demonstrate that indeed tholin-like haze formation could occur on condensed aerosols throughout the atmospheric column of Titan. Detected in Titan's atmosphere, dicyanoacetylene (C?N?) is used in our laboratory simulations as a model system for other larger unsaturated condensing compounds. We show that C4N2 ices undergo condensed-phase photopolymerization (tholin formation) at wavelengths as long as 355 nm pertinent to solar radiation reaching a large portion of Titan's atmosphere, almost close to the surface. PMID:23552063

Gudipati, Murthy S; Jacovi, Ronen; Couturier-Tamburelli, Isabelle; Lignell, Antti; Allen, Mark

2013-01-01

432

Dehydration and Symptoms of Delayed-Onset Muscle Soreness in Hyperthermic Males  

PubMed Central

Context: Exercise in the heat produces cellular conditions that may leave skeletal muscle susceptible to exercise-induced microdamage. Delayed-onset muscle soreness (DOMS) is a clinical model of contraction-induced skeletal muscle injury. Objective: To determine whether thermoregulation during exercise heat stress adversely affects muscle injury and the accompanying DOMS. Design: Randomized group test-retest design. Setting: Laboratory. Patients or Other Participants: Ten healthy male volunteers were randomly assigned to either the euhydration/hyperthermic or dehydration/hyperthermic group. Intervention(s): Participants were randomly assigned to treadmill walking in a hot, humid environmental chamber (40°C and 75% relative humidity) with either oral rehydration (euhydration/hyperthermic) or fluid restriction (dehydration/hyperthermic). Immediately after heat exposure and while hyperthermic, participants performed an eccentrically biased downhill run to induce DOMS. Main Outcome Measure(s): We measured DOMS characteristics pre-exercise and at 0.5, 24, 48, 72, and 96 hours postexercise. Results: Treadmill exercise and exposure to the hot ambient environment elicited a 0.9% body mass loss for the euhydrated/ hyperthermic (mean rectal temperature after 60 minutes of heat-stress trial = 38.2 ± 0.4°C) and 3.3% body mass loss for the dehydrated/hyperthermic participants (mean rectal temperature after 60 minutes of heat-stress trial = 38.1 ± 0.4°C). Quadriceps perceived pain was significantly higher (F5,40 = 18.717, P ? .001) than baseline at 24 and 48 hours postexercise, following the classic pattern of DOMS. Overall lower extremity perceived pain was significantly higher for the dehydration/hyperthermia group than the euhydration/hyperthermia group (F1,8 = 6.713, P = .032). Punctate tenderness of the vastus lateralis for the dehydration/hyperthermic group was 6.9% higher (F5,40 = 4.462, P = .003) than for the euhydration/ hyperthermic group. No clinically important findings were revealed for passive range of motion for knee flexion. For both groups, quadriceps isometric strength (F5,40 = 12.924, P ? .001) was 17.5% and 20.0% lower at 0.5 hours postexercise than at 72 and 96 hours postexercise, respectively. Further, quadriceps isometric strength remained 10.5% reduced at 24 hours postexercise compared with 96 hours postexercise. Conclusions: Skeletal muscle microdamage, indirectly evidenced by DOMS, was exacerbated in hyperthermic participants dehydrated by exercise in a hot ambient environment. Individuals performing novel exercise, particularly with a significant eccentric component, should use caution when training in a hot, humid environment and implement frequent rest and rehydration breaks. PMID:16404450

Cleary, Michelle A; Sweeney, Lori A; Kendrick, Zebulon V; Sitler, Michael R

2005-01-01

433

Role of condensed phase details in the oscillatory combustion of composite propellants  

NASA Technical Reports Server (NTRS)

The response functions of composite propellants are theoretically derived, including explicitly the pressure-dependent degradation term in the condensed phase, hypothesizing that the overall rate-limiting reactions are in the relatively low temperature condensed phase. The method of 'inner' and 'outer' expansions with the reduced activation energy as the singular perturbation parameter has been employed. The results cover subsurface reactions with and without surface reactions, adiabatic and uniform-combustion models for the quasi-steady gas phase processes. The response functions display several experimentally observed features like dependence on mean pressure and the instability behavior of some 'zero-n' propellants.

Kumar, R. N.; Culick, F. E. C.

1977-01-01

434

Steam condenser thermal design theories  

NASA Astrophysics Data System (ADS)

Test data and prediction methods for condensation in steam condenser tube banks are reviewed. Standards for thermal rating; effect of vapor velocity; vapor shear and inundation in tube banks; correction factors to the Nusselt equation; and equations for the combined effect of vapor shear and inundation are discussed. Effects of noncondensible gases; tube side heat transfer; and expressions for combined tube side and shell side heat transfer are considered. Frictional, gravitational, momentum, and pressure drop trends; and the role of access lanes to reduce pressure drop are outlined. Computer models of condensers, including algebraic representations of the field equations, are summarized.

Davidson, B. J.

435

Condensate Density and Superfluid Mass Density of a Dilute Bose-Einstein Condensate near the Condensation Transition  

E-print Network

in the system size. A self-consistent two- loop calculation yields the condensate fraction critical exponent, 2Condensate Density and Superfluid Mass Density of a Dilute Bose-Einstein Condensate near the Condensation Transition Markus Holzmann1,2 and Gordon Baym1 1 University of Illinois at Urbana-Champaign, 1110

436

Reactions of cresol in hot aqueous borate solutions  

SciTech Connect

Phenol and methylphenol (cresol) are constituents of certain waste streams being considered for underground injection. We studied reactions of these compounds in solutions with other constituents of the waste streams and suspended clay at concentrations and temperatures higher than expected in natural situations, i.e. at 200{degrees}C and 250{degrees}C. Under these conditions, the predominant reaction was the demethylation of cresol to form phenol. This reaction was catalyzed strongly by clay. We were able to quantify phenol production. Other important reactions were a variety of condensation reactions in which two cresol molecules fuse. We found evidence of the intermolecular migration of methyl groups from the molecular weights of some of these condensation reactions. By digesting a sample of reacted clay with hydrofluoric acid we determined that under these conditions phenol and cresol did not bind appreciably to clay but that the condensation products did.

Tsao, L. [Lawrence Berkeley Lab., CA (United States); Weres, O. [Sonoma Research Co., Vineburg, CA (United States)

1992-04-01

437

Use of aluminum phosphate as the dehydration catalyst in single step dimethyl ether process  

DOEpatents

The present invention pertains to a process for the coproduction of methanol and dimethyl ether (DME) directly from a synthesis gas in a single step (hereafter, the "single step DME process"). In this process, the synthesis gas comprising hydrogen and carbon oxides is contacted with a dual catalyst system comprising a physical mixture of a methanol synthesis catalyst and a methanol dehydration catalyst. The present invention is an improvement to this process for providing an active and stable catalyst system. The improvement comprises the use of an aluminum phosphate based catalyst as the methanol dehydration catalyst. Due to its moderate acidity, such a catalyst avoids the coke formation and catalyst interaction problems associated with the conventional dual catalyst systems taught for the single step DME process.

Peng, Xiang-Dong (Allentown, PA); Parris, Gene E. (Coopersburg, PA); Toseland, Bernard A. (Allentown, PA); Battavio, Paula J. (Allentown, PA)

1998-01-01

438

Influence of burnabl absorbers on the dehydration effect of an RBMK reactor  

SciTech Connect

Erbium is promising as a burnable absorber for RBMK reactors. Addition of erbium to 2.4%-enriched fuel makes it possible, while maintaining or only slightly reducing the dehydration effect, to do without auxiliary absorbers and to decrease the maximum fuel-assembly power by 15% without reduce the uranium burnup. It is thus becoming feasible to increase the power of RBMK reactors, primarily the RBMK-1000 and also the RBMK-1500, which had been lowered for safety considerations. Raising the enrichment to 3% and at the same time using erbium makes it possible to obtain a negative dehydration effect, further level out the fuel-assembly power, and increase the fuel burn-up, thus reducing the amount of spent fuel. The safety of existing RBMK reactors is enhance substantially without altering the fuel-assembly design and increasing the channel diameter, as is done in the other promising approach.

Fedosov, A.M.

1994-01-01

439

Limited magnesium isotope fractionation during metamorphic dehydration in metapelites from the Onawa contact aureole, Maine  

NASA Astrophysics Data System (ADS)

on the behavior of Mg isotopes during metamorphic dehydration is the prerequisite for applying Mg isotopes as tracers for crustal recycling. Here we report Mg isotopic compositions of metapelites from the Onawa contact aureole, Maine. Except one sample, all metapelites across the aureole, from the wall-rock regional metamorphic rocks to the partially melted rocks adjacent to the pluton, have similar Mg isotopic compositions (?26Mg = -0.09 to +0.12‰). This observation indicates limited Mg isotope fractionation during metamorphic dehydration and fluid-rock interaction, due to the low Mg concentration in fluids relative to rocks. Our results suggest that Mg isotopic compositions of metapelites can record those of their protoliths and, hence, recycled clastic sedimentary materials may preserve their low-temperature Mg isotopic signatures through subduction zones. Therefore, Mg isotopes may serve as new tracers for crustal recycling, for example, tracing components experienced weathering cycles within granite sources.

Li, Wang-Ye; Teng, Fang-Zhen; Wing, Boswell A.; Xiao, Yilin

2014-02-01

440

Fructose dehydration to 5-hydroxymethylfurfural over solid acid catalysts in a biphasic system.  

PubMed

Different acidic heterogeneous catalysts like alumina, aluminosilicate, zirconium phosphate, niobic acid, ion-exchange resin Amberlyst-15, and zeolite MOR have been studied in fructose dehydration to 5-hydroxymethylfurfural (HMF). The acidity of these materials was characterized using temperature-programmed desorption of NH? and IR spectroscopy of adsorbed pyridine. The nature and strength of acid sites was shown to play a crucial role in the selectivity towards HMF. Brønsted acid sites in the case of zeolites and ion-exchange resin led to high selectivities in the dehydration of fructose with an increase in selectivity with the addition of an organic phase. Lewis acidity in the case of phosphate and oxides resulted in the intensive production of humins from fructose at the initial stages of the process, whereas organic phase addition did not affect selectivity. PMID:22777706

Ordomsky, Vitaly V; van der Schaaf, John; Schouten, Jaap C; Nijhuis, T Alexander

2012-09-01

441

Effect of sucrose and binary solution on osmotic dehydration of bell pepper (chilli) (Capsicum spp.) varieties.  

PubMed

Pepper (chilli) (Capsicum annum) varieties, 'Tatase' and 'Rodo', (Capsicum frutescens) 'Sombo' and 'Bawa' were osmotically dehydrated in sucrose solutions of 40, 50 and 60o Brix and binary solutions of 50° sucrose with 5, 10 and 15% salt at 20, 30 and 40°C for 9 h. Samples osmosed at higher sugar concentrations (50° and 60°Brix) gave better results while improved solute gain were obtained using binary mixture with lower processing time, energy and cost. Effects of varietal differences on solid gain and water loss showed a descending in the order 'Sombo', 'Rodo', 'Bawa' and 'Tatase'. The colours were retained and stabilized after osmotic dehydration. Therefore, the solid gain and colour retention are indications of value addition. PMID:23572642

Raji Abdul Ganiy, O; Falade Kolawole, O; Abimbolu Fadeke, W

2010-06-01

442

Epoxidation in Vivo of Hyoscyamine to Scopolamine Does Not Involve a Dehydration Step  

PubMed Central

Hyoscyamine is epoxidized to scopolamine via 6?-hydroxyhyoscyamine in several solanaceous plants. 6,7-Dehydrohyoscyamine has been proposed to be an intermediate in the conversion of 6?-hydroxyhyoscyamine to scopolamine on the basis of the observation that this unsaturated alkaloid is converted to scopolamine when fed to a Datura scion. To determine whether a dehydration step is involved in scopolamine biosynthesis, [6-18O]6?-hydroxyhyoscyamine was prepared from l-hyoscyamine and 18O2 using hyoscyamine 6?-hydroxylase obtained from root cultures of Hyoscyamus niger L. When [6-18O]6?-hydroxyhyoscyamine was fed to shoot cultures of Duboisia myoporoides R. BR., the labeled alkaloid was converted to scopolamine which retained 18O in the epoxide oxygen. It is concluded that 6?-hydroxyhyoscyamine is converted in vivo to scopolamine without a dehydration step. PMID:16665388

Hashimoto, Takashi; Kohno, Junko; Yamada, Yasuyuki

1987-01-01

443

Earth's interior. Dehydration melting at the top of the lower mantle.  

PubMed

The high water storage capacity of minerals in Earth's mantle transition zone (410- to 660-kilometer depth) implies the possibility of a deep H2O reservoir, which could cause dehydration melting of vertically flowing mantle. We examined the effects of downwelling from the transition zone into the lower mantle with high-pressure laboratory experiments, numerical modeling, and seismic P-to-S conversions recorded by a dense seismic array in North America. In experiments, the transition of hydrous ringwoodite to perovskite and (Mg,Fe)O produces intergranular melt. Detections of abrupt decreases in seismic velocity where downwelling mantle is inferred are consistent with partial melt below 660 kilometers. These results suggest hydration of a large region of the transition zone and that dehydration melting may act to trap H2O in the transition zone. PMID:24926016

Schmandt, Brandon; Jacobsen, Steven D; Becker, Thorsten W; Liu, Zhenxian; Dueker, Kenneth G

2014-06-13

444

Relationship in humans between atrial natriuretic peptide and arginine vasopressin during dehydration  

SciTech Connect

The present study was designed to define in normal humans (n=6) the relationship between atrial natriuretic peptide (ANP) and arginine vasopressin (AVP) during thirty-six hours of dehydration. Atrial natriuretic peptide was measured from extracted plasma by radioimmunoassay to alpha-human atrial natriuretic peptide; arginine vasopressin was measured from platelet free plasma by specific radioimmunoassay to AVP. Determinations were obtained of ANP, AVP and plasma osmolality (Posm) prior to and following fluid deprivation for thirty-six hours. The present study demonstrates that dehydration in humans increases plasma osmolality and arginine vasopressin but does not increase atrial natriuretic peptide. These investigations importantly dissociate these two peptide hormonal systems during the physiologic adaptation to fluid deprivation.

Burnett, J.C. Jr.; Wilson, D.M.; Kao, P.C.; Schwab, T.R.; Heublein, D.M.; Heser, D.W.

1986-03-01

445

Structure Investigation of Metal Ions Clustering in Dehydrated Gel Using X-ray Anomalous Dispersion Effect  

NASA Astrophysics Data System (ADS)

The structure of copper ion clusters in dehydrated N-isopropylacrylamide/sodium acrylate (NIPA/SA) gel has been studied by means of small angle X-ray scattering (SAXS) method. In order to distinguish the intensity scattered by Cu ions, the X-ray anomalous dispersion effect around the Cu K absorption edge has been coupled with SAXS. It is found that the dispersion effect dependent on the incident X-ray energy is remarkable only at the momentum transfer q=0.031 Å-1, where a SAXS peak is observed. The results indicate that copper ions form clusters in the dehydrated gel, and that the mean size of clusters is the same as that of SA clusters produced by microphase separation.It is therefore naturally presumed that copper ions are adsorbed into the SA molecules. On the basis of the presumption, a mechanism is proposed for microphase-separation and clustering of Cu ions.

Soejima, Yuji; Kuwajima, Shuichiro; Sugiyama, Masaaki; Annaka, Masahiko; Nakamura, Atsushi; Hiramatsu, Nobuyasu; Hara, Kazuhiro

2003-08-01

446