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Water equilibrium

Wen-Bo Rao, Liang-Feng Han, Hong-Bing Tan, Shuai Wang
Soil samples containing water with known stable isotopic compositions were prepared. The soil water was recovered by using vacuum/heat distillation. The experiments were held under different conditions to control rates of water evaporation and water recovery. Recoveries, δ(18)O and δ(2)H values of the soil water were determined. Analyses of the data using a Rayleigh distillation model indicate that under the experimental conditions only loosely bound water is extractable in cases where the recovery is smaller than 100 %...
December 5, 2016: Isotopes in Environmental and Health Studies
Luca Evangelisti, Qian Gou, Gang Feng, Walther Caminati, Griffin J Mead, Ian A Finneran, P Brandon Carroll, Geoffrey A Blake
The molecular complex between iso-propanol and water has been investigated by Fourier transform microwave spectroscopy. Two distinct rotational spectra have been assigned, corresponding to two different isomers of the adduct. In both cases the water molecule acts as a proton donor to the alcoholic oxygen atom of iso-propanol in its gauche arrangement. The isomer in which the water molecule is oriented along the symmetry plane of the iso-propanol molecule (inner) is more stable than the second isomer, where the water is positioned outside the iso-propanol symmetry plane (outer)...
December 5, 2016: Physical Chemistry Chemical Physics: PCCP
Moreno Marcellini, Cecile Noirjean, Dmytro Dedovets, Juliette Maria, Sylvain Deville
Ice crystals nucleate and grow when a water solution is cooled below its freezing point. The growth velocities and morphologies of the ice crystals depend on many parameters, such as the temperature of ice growth, the melting temperature, and the interactions of solutes with the growing crystals. Three types of morphologies may appear: dendritic, cellular (or fingerlike), or the faceted equilibrium form. Understanding and controlling which type of morphology is formed is essential in several domains, from biology to geophysics and materials science...
November 30, 2016: ACS Omega
Vladan Vučković, Dragana Vujović
A chemistry module with the aqueous chemistry coupled with the complex 3D nonhydrostatic atmospheric model is used to investigate how the representation of gas-aqueous mass transfer and ice retention affect the SO2 redistribution in the presence of a convective cloud. Gas uptake to the liquid water is calculated using both Henry's law equilibrium (HE) and kinetic mass transport (KMT). The constant retention coefficients for SO2 (k ret = 0.46) and for H2O2 (k ret = 0.64) are used. It is shown that the amount of SO2 in the air at higher altitudes (10-12 km) is greater when partial retention (PR) is included...
December 2, 2016: Environmental Science and Pollution Research International
Dagang Song, Kaiwen Pan, Akash Tariq, Azizullah Azizullah, Feng Sun, Zilong Li, Qinli Xiong
Environmental pollution with heavy metals is a serious issue worldwide posing threats to humans, animals and plants and to the stability of overall ecosystem. Chromium (Cr) is one of most hazardous heavy metals with a high carcinogenic and recalcitrant nature. Aim of the present study was to select low-cost biosorbent using wheat straw and Eupatorium adenophorum through simple carbonization process, capable of removing Cr (VI) efficiently from wastewater. From studied plants a low cost adsorbent was prepared for removing Cr (VI) from aqueous solution following very simple carbonization method excluding activation process...
2016: PloS One
Zdenek Futera, Niall J English
We have performed non-equilibrium molecular dynamics simulations of various TiO2/water interfaces at ambient temperature in presence of oscillating electric fields in frequency range 20-100 GHz and RMS intensities 0.05-0.25 V/Å. Although the externally applied fields are by one order of magnitude lower than the intrinsic electric field present on the interfaces (∼1.5-4.5 V/Å), significant non-thermal coupling of rotational and translational motion of water molecules was clearly observed. Enhancement of the motion, manifested by increase of diffusivity, was detected in the first hydration layer, which is known to be heavily confined by adsorption to the TiO2 surface...
November 28, 2016: Journal of Chemical Physics
Prithwish K Nandi, Zdenek Futera, Niall J English
Given the fundamental role of water in governing the biochemistry of enzymes, and in regulating their wider biological activity (e.g., by local water concentration surrounding biomolecules), the influence of extraneous electric and electromagnetic (e/m) fields thereon is of central relevance to biophysics and, more widely, biology. With the increase in levels of local and atmospheric microwave-frequency radiation present in modern life, as well as other electric-field exposure, the impact upon hydration-water layers surrounding proteins, and biomolecules generally, becomes a particularly pertinent issue...
November 28, 2016: Journal of Chemical Physics
Yiping Duan, Mingshi Feng, Xinyan Zhong, Ruishu Shang, Lihong Huang
Carbonate cements, such as calcite, dolomite, ferrocalcite and ankerite, play important roles in the formation of pores in sandstones: precipitation of carbonate cements modifies pores and inhibits compaction, while dissolution creates secondary pores. This work proposed a precipitation-dissolution model for carbonate cements-CO2-H2O system by means of ion equilibrium concentration ([M2+], M = Ca, Mg, Fe or Mn) with different factors, such as temperature, depth, pH, [Formula: see text], variable rock composition and overpressure...
2016: PloS One
Erik R Reale, Alison C Dunn
It is widely accepted that hydrogel surfaces are slippery, and have low friction, but dynamic applied stresses alter the hydrogel composition at the interface as water is displaced. The induced osmotic imbalance of compressed hydrogel which cannot swell to equilibrium should drive the resistance to slip against it. This paper demonstrates the driving role of poroelasticity in the friction of hydrogel-glass interfaces, specifically how poroelastic relaxation of hydrogels increases adhesion. We translate the work of adhesion into an effective surface energy density that increases with the duration of applied pressure from 10 to 50 mJ m(-2), as measured by micro-indentation...
November 30, 2016: Soft Matter
Pouyan Jahangiri, Riley Doering, Simon Ferguson, Keana Li, Ken Buckley, François Bénard, D Mark Martinez, Cornelia Hoehr
The steady-state behaviour of a liquid target used to produce medical isotopes by low-energy cyclotrons is studied. A model based on the conservation of mass and energy is proposed to describe the pressure rise of the target assuming equilibrium between liquid and vapour phases during irradiation. The effects of water radiolysis are taken into account. Excellent agreement is achieved between the model, and both constant-temperature bath tests and experiments conducted on a 13MeV cyclotron at TRIUMF.
November 15, 2016: Applied Radiation and Isotopes
Bo-Wen Pang, Cheng-Hong Jiang, Marvin Yeung, Yun Ouyang, Jinying Xi
Activated sludge recycling has been developed as a novel technique to directly prevent volatile sulfides emission from wastewater influents. In this study, mechanisms and characteristics of dissolved sulfides removal in aqueous solution by activated sludge were investigated. When DO content in water was 0.49mg/L, 70% of removed dissolved sulfides were released back from the activated sludge by lowering pH to 1. The SEM/EDS result revealed that removed sulfur was fixed in activated sludge and the XPS result showed that fixed sulfur had an oxidation state of -2...
November 18, 2016: Journal of Hazardous Materials
Hanna Siwek, Artur Bartkowiak, Małgorzata Włodarczyk, Katarzyna Sobecka
Binding phosphate at participation of alginate/FeCl3 capsules was studied with laboratory experiments. The hydrogel microcapsules were obtained with the dropping-in method, by gelation of sodium alginate water solution by iron (III) chloride solution. Phosphate adsorption characteristics were studied in a static batch system with respect to changes in contact time, initial phosphates concentration, pH of solution, and temperature. After 24 h of the tests, average 87.5% of phosphate ions were removed from the natural water solutions; after 48 h, an equilibrium was reached...
2016: Water, Air, and Soil Pollution
Kasper Wigh Lipsø, Sean Bowen, Oleksandr Rybalko, Jan Henrik Ardenkjær-Larsen
We demonstrate a method for the preparation of hyperpolarized water by dissolution Dynamic Nuclear Polarization at high magnetic field. Protons were polarized at 6.7T and 1.1K to >70% with frequency modulated microwave irradiation at 188GHz. 97.2±0.7% of the radical was extracted from the sample in the dissolution in a two-phase system. 16±1mL of 5.0M (1)H in D2O with a polarization of 13.0±0.9% in the liquid state was obtained, corresponding to an enhancement factor of 4000±300 compared to the thermal equilibrium at 9...
November 18, 2016: Journal of Magnetic Resonance
Herakles A Garcia, Oneyda J Ramírez, Carla M F Rodrigues, Rafael G Sánchez, Angelica M Bethencourt, Gabriela Del M Pérez, Antonio H H Minervino, Adriana C Rodrigues, Marta M G Teixeira
Trypanosoma vivax has been associated with asymptomatic infections in African and South American buffalo. In this study, T. vivax was analyzed in water buffalo (Bubalus bubalis) from Venezuela in a molecular survey involving 293 blood samples collected from 2006 to 2015 across the Llanos region. Results demonstrated constant infections (average 23%) during the years analyzed. In general, animals were healthy carriers of T. vivax with low levels of parasitemia and were diagnosed exclusively by TviCATL-PCR. However, an outbreak of severe acute infections mostly in dairy animals was reported during a prolonged drought affecting 30...
October 30, 2016: Veterinary Parasitology
Koen Dijkstra, Jeannette Hofmeijer, Stephan A van Gils, Michel J A M van Putten
: We present a dynamic biophysical model to explain neuronal swelling underlying cytotoxic edema in conditions of low energy supply, as observed in cerebral ischemia. Our model contains Hodgkin-Huxley-type ion currents, a recently discovered voltage-gated chloride flux through the ion exchanger SLC26A11, active KCC2-mediated chloride extrusion, and ATP-dependent pumps. The model predicts changes in ion gradients and cell swelling during ischemia of various severity or channel blockage with realistic timescales...
November 23, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Kazuo Yamazaki, Xueying Wang
We study the global stability issue of the reaction-convection-diffusion cholera epidemic PDE model and show that the basic reproduction number serves as a threshold parameter that predicts whether cholera will persist or become globally extinct. Specifically, when the basic reproduction number is beneath one, we show that the disease-free-equilibrium is globally attractive. On the other hand, when the basic reproduction number exceeds one, if the infectious hosts or the concentration of bacteria in the contaminated water are not initially identically zero, we prove the uniform persistence result and that there exists at least one positive steady state...
April 1, 2017: Mathematical Biosciences and Engineering: MBE
Paweł Sutkowy, Alina Woźniak, Tomasz Boraczyński, Michał Boraczyński, Celestyna Mila-Kierzenkowska
The goal of the study was to evaluate the effect of an aerobic exercise bout followed by ice-water immersion or recovery at room temperature on the redox state, activities of selected lysosomal enzymes and activity of α1-antitrypsin (AAT) in the blood of healthy sportsmen. Eleven amateur football players aged 18 were randomly assigned to two similar 30-min aerobic cycle ergometer tests followed by a recovery at room temperature (20 °C; Experiment 1) or ice-water immersion (3 °C, 5 min; Experiment 2). Peripheral blood was collected three times during both study experiments: before (baseline), as well as 20 and 40 min after the recovery or immersion...
November 18, 2016: Cryobiology
E W Slessarev, Y Lin, N L Bingham, J E Johnson, Y Dai, J P Schimel, O A Chadwick
Soil pH regulates the capacity of soils to store and supply nutrients, and thus contributes substantially to controlling productivity in terrestrial ecosystems. However, soil pH is not an independent regulator of soil fertility-rather, it is ultimately controlled by environmental forcing. In particular, small changes in water balance cause a steep transition from alkaline to acid soils across natural climate gradients. Although the processes governing this threshold in soil pH are well understood, the threshold has not been quantified at the global scale, where the influence of climate may be confounded by the effects of topography and mineralogy...
November 21, 2016: Nature
F-D Kopinke, A Georgi, G Imfeld, H-H Richnow
Isotope fractionation between benzene-D0 and benzene-D6 caused by multi-step partitioning of the benzenes between water and two organic solvents, n-octane and 1-octanol, as well as between water and the gas phase, was measured. The obtained fractionation factors αH = KH/KD are αH = 1.080 ± 0.015 and αH = 1.074 ± 0.015 for extraction into n-octane and 1-octanol, respectively, and αH = 1.049 ± 0.010 for evaporation from aqueous solution. The comparison of solvent- and gas-phase partitioning reveals that about 2/3 of the driving force of fractionation is due to different interactions in the aqueous phase, whereas 1/3 is due to different interactions in the organic phase...
November 18, 2016: Chemosphere
Fouad S Husseini, David Robinson, Neil T Hunt, Anthony W Parker, Jonathan D Hirst
The ability to compute from first principles the infrared spectrum of a protein in solution phase representing a biological system would provide a useful connection to atomistic models of protein structure and dynamics. Indeed, such calculations are a vital complement to 2DIR experimental measurements, allowing the observed signals to be interpreted in terms of detailed structural and dynamical information. In this article, we have studied nine structurally and spectroscopically well-characterized proteins, representing a range of structural types...
November 21, 2016: Journal of Computational Chemistry
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