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Water equilibrium

Xing Wang, Harro A J Meijer
The stable isotopes of water are extensively used as tracers in many fields of research. For this use, it is essential to know the isotope fractionation factors connected to various processes, the most important of which being phase changes. Many experimental studies have been performed on phase change fractionation over the last decades. Whereas liquid-vapour fractionation measurements are relatively straightforward, vapour-solid and liquid-solid fractionation measurements are more complicated, as maintaining equilibrium conditions when a solid is involved is difficult...
February 15, 2018: Isotopes in Environmental and Health Studies
Laith Furatian, Madjid Mohseni
The use of 185 nm radiation from a conventional low pressure mercury lamp generates the hydroxyl radical (OH) from the photolysis of water and offers an advanced oxidation process (AOP) for water treatment that does not require chemical addition. However, the influence of the water matrix on the process differs substantially from that of other ultraviolet and ozone based processes. In particular chloride (Cl - ), and not water, absorbs the majority of 185 nm photons when [Cl - ]>20mgL -1 and generates the chlorine atom radical (Cl) as a reactive species...
February 3, 2018: Chemosphere
Tsuyoshi Matsuda, Hirohiko Kimura, Hiroyuki Kabasawa, Masayuki Kanamoto
On arterial spin-labeled (ASL) images, areas of bright intravascular signal will appear when the post labeling delay time is shorter than arterial transit time. Vascular suppression (VS) schemes reduce artefactual bright signal by dephasing intravascular labeled spins. However, existing VS methods, such as Motion-Sensitized Driven-Equilibrium (MSDE), decrease the uniformity of the signal intensity distribution and extend the echo time. The purpose of this study is to compare VS using a Delays Alternating with Nutation for Tailored Excitation (DANTE) preparation pulse, with MSDE for ASL imaging on a flow phantom and volunteer data...
February 12, 2018: Magnetic Resonance Imaging
Divya Nayar, Nico F A van der Vegt
Water-mediated hydrophobic interactions play an important role in self-assembly processes, aqueous polymer solubility, and protein folding, to name a few. Cosolvents affect these interactions however the implications for hydrophobic polymer collapse and protein folding equilibria are not well-understood. This study examines cosolvent effects on the hydrophobic collapse equilibrium of a generic 32-mer hydrophobic polymer in urea, trimethylamine-N-oxide (TMAO), and acetone aqueous solutions using molecular dynamics simulations...
February 14, 2018: Journal of Physical Chemistry. B
Chang-Yan Xu, Xiao-Mei Shi, Lu Guo, Xi Wang, Xin-Yi Wang, Jian-Yu Li
With the pace of development accelerating in printed electronics, the fabrication and application of conductive ink have been brought into sharp focus in recent years. The discovery of graphene also unfolded a vigorous research campaign. In this paper, we prepared graphene conductive ink and explored the feasibility of applying the ink to flexible paper-based circuit. Since experimental study concentrating upon ink formulation was insufficient, orthogonal test design was used in the optimization of preparation formula of conductive ink for the first time...
June 1, 2018: Journal of Nanoscience and Nanotechnology
Nadia Shardt, Janet A W Elliott
At any given temperature, pressure, and composition, a compound or a mixture of compounds will exist either in a single phase, whether solid, liquid, or vapor, or in a combination of these phases coexisting in equilibrium. For multiphase systems, it is known that the geometry of the interface impacts the equilibrium state; this effect has been well-studied in single component systems with spherical interfaces. However, multicomponent phase diagrams are usually calculated assuming a planar interface between phases...
February 14, 2018: Journal of Physical Chemistry. B
Kai-Uwe Goss, Kai Bittermann, Luise Henneberger, Lukas Linden
In this work we combine partition coefficients between water and membrane lipid, storage lipid, the plasma protein albumin as well as structural protein with the tissue dependent fraction of the respective phases in order to obtain a clearer picture on the relevance of various biological tissues for the bioaccumulation of 31 organic anions. Most of the partition coefficients are based on experimental data, supplemented by some predicted ones. The data suggest that the plasma protein, albumin, will be the major sorption matrix in mammals...
February 6, 2018: Chemosphere
María F Sánchez Goñi, Stéphanie Desprat, William J Fletcher, César Morales-Molino, Filipa Naughton, Dulce Oliveira, Dunia H Urrego, Coralie Zorzi
Pollen from deep-sea sedimentary sequences provides an integrated regional reconstruction of vegetation and climate (temperature, precipitation, and seasonality) on the adjacent continent. More importantly, the direct correlation of pollen, marine and ice indicators allows comparison of the atmospheric climatic changes that have affected the continent with the response of the Earth's other reservoirs, i.e., the oceans and cryosphere, without any chronological uncertainty. The study of long continuous pollen records from the European margin has revealed a changing and complex interplay between European climate, North Atlantic sea surface temperatures (SSTs), ice growth and decay, and high- and low-latitude forcing at orbital and millennial timescales...
2018: Frontiers in Plant Science
Gabriele Weigelhofer, José Pedro Ramião, Beate Pitzl, Elisabeth Bondar-Kunze, Joanna O'Keeffe
Our study aimed to explore the effects of agriculture on the phosphorus buffer capacity of 11 headwater streams in Austria. We used phosphorus adsorption curves and re-suspension experiments to determine both, the potential of the sediments to act as phosphorus source or sink and the actual phosphorus exchange between water and sediments. Additionally, we determined the alkaline phosphatase activity (APA) in epilithic and epipsammic biofilms as indicator for the phosphorus demand of the benthic and hyporheic community...
February 8, 2018: Science of the Total Environment
Jingyu Li, Lulu Han, Shuxin Liu, Sai He, Yaming Cao, Jian Xie, Lingyun Jia
Indoxyl sulfate (IS) is a uremic toxin related to the progression of chronic kidney diseases. Removal of IS from the plasma would reduce the risk of cardiovascular disease. In this study, crosslinked poly-β-cyclodextrins (PCDs) were used as a water-soluble adsorbent agent for IS in dialysis for the first time. The molecular weight of PCDs was found to be proportional to the crosslinking time between β-cyclodextrin monomers and epichlorohydrin, yet the proportion of β-cyclodextrin that reacted with epichlorohydrin decreased...
January 31, 2018: Colloids and Surfaces. B, Biointerfaces
Zhiming Shi, Fangfang Zhang, Congying Wang
The fate of hydrophobic organic contaminants (HOCs) in soil-earthworm systems is an important foundation for soil pollution risk assessment and pollution control. Equilibrium partitioning is considered to be the main mechanism by which HOCs enter earthworms and, as such, a mechanistic model has been developed to estimate the earthworm-water partition coefficients (Kw-w). In the present study, the adsorption of phenanthrene (PHE) by earthworm tissue was investigated to evaluate the validity of the mechanistic models...
February 8, 2018: Journal of Environmental Management
Yoonah Jeong, Andreas Schäffer, Kilian Smith
In this work, Oasis HLB® beads were embedded in a silicone matrix to make a single phase passive sampler with a higher affinity for polar and ionisable compounds than silicone alone. The applicability of this mixed polymer sampler (MPS) was investigated for 34 aquatic contaminants (log KOW -0.03 to 6.26) in batch experiments. The influence of flow was investigated by comparing uptake under static and stirred conditions. The sampler characteristics of the MPS was assessed in terms of sampling rates (RS) and sampler-water partition coefficients (KSW), and these were compared to those of the polar organic chemical integrative sampler (POCIS) as a reference kinetic passive sampler...
February 2, 2018: Science of the Total Environment
Kristine M Fischenich, Jackson T Lewis, Travis S Bailey, Tammy L Haut Donahue
Hydrogels are a class of synthetic biomaterials composed of a polymer network that swells with water and as such they have both an elastic and viscous component making them ideal for soft tissue applications. This study characterizes the compressive, tensile, and shear properties of a thermoplastic elastomer (TPE) hydrogel and compares the results to published literature values for soft tissues such as articular cartilage, the knee meniscus, and intervertebral disc components. The results show the TPE hydrogel material is viscoelastic, strain rate dependent, has similar surface and bulk properties, displays minimal damping under dynamic load, and has tension-compression asymmetry...
March 2018: Journal of the Mechanical Behavior of Biomedical Materials
Adam J Rieth, Mircea Dinca
Ammonia is a vital commodity in our food supply chain, but its toxicity and corrosiveness require advanced protection and mitigation. These needs are not met efficiently by current materials, which suffer from either low capacity or low affinity for NH3. Here, we report that a series of microporous triazolate metal-organic frameworks containing open metal sites exhibit record static and dynamic ammonia capacities. Under equilibrium conditions at 1 bar the materials adsorb up to 19.79 mmol NH3 g-1, more than twice the capacity of activated carbon, the industry standard...
February 9, 2018: Journal of the American Chemical Society
Asif Ahmed, Joshua Boateng
AIM: Diabetic foot ulcers are susceptible to infection and nonmedicated dressings are ineffective because they have no antimicrobial activity. This study aimed to develop antimicrobial films to deliver ciprofloxacin for treating bacterial infection. Results/methodology: Ciprofloxacin-loaded calcium alginate films were characterized for porosity, swelling, equilibrium water content, water absorption, water vapor transmission, evaporative water loss, moisture content, mechanical strength, adhesion, IR spectroscopy, scanning electron microscopy, x-ray diffraction, drug release, cytotoxicity and antimicrobial activity against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa...
February 1, 2018: Therapeutic Delivery
Stephane Kenmoe, P Ulrich Biedermann
ZnO nanoparticles are used as catalysts and have potential applications in gas-sensing and solar energy conversion. A fundamental understanding of the exposed crystal facets, their surface chemistry, and stability as a function of environmental conditions is essential for rational design and improvement of synthesis and properties. We study the stability of water adsorbate phases on the non-polar low-index (101¯0) and (112¯0) surfaces from low coverage to multilayers using ab initio thermodynamics. We show that phonon contributions and the entropies due to a 2D lattice gas at low coverage and multiple adsorbate configurations at higher coverage have an important impact on the stability range of water adsorbate phases in the (T,p) phase diagram...
February 7, 2018: Journal of Chemical Physics
Alexander Pazur
Weak magnetic and electromagnetic fields affect physiological processes in animals, plants, and microorganisms. Ion cyclotron resonance (ICR) is discussed as one of the sensitive mechanisms, which enable perception of the geomagnetic field and its orientation. Numerous biological effects are observed involving several small ions, showing windows of predicted frequencies and intensities. The pioneering work of Guiliano Preparata and Emilio Del Giudice using quantum electrodynamics showed that spontaneously originating coherent regions in water facilitate ICR effects at incoherent water phase boundaries...
February 8, 2018: Electromagnetic Biology and Medicine
Saskia Rehse, Werner Kloas, Christiane Zarfl
Abstract: Microplastics can have direct physical effects on organisms in freshwater systems, and are considered as vectors for absorbed environmental pollutants. It is still under discussion if microplastics are relevant pollutant vectors for uptake into aquatic organisms in comparison to further uptake pathways, e.g., via water or sediment particles. We analyzed how the presence of microplastics (polyamide particles, PA) modifies acute effects of the environmental pollutant bisphenol A (BPA) on freshwater zooplankton (Daphnia magna)...
February 6, 2018: International Journal of Environmental Research and Public Health
Christopher J Russo, Richard Henderson
When irradiated in a transmission electron microscope, plunge-frozen, amorphous water ice specimens accumulate a pattern of static charge that changes dynamically as the specimen is irradiated, and which can deflect the transmitted electrons and blur the resultant micrographs. Here we provide a physical description of this charge accumulation and characterise its dynamic behaviour in the context of low-dose electron cryomicroscopy (cryoEM). We observe the accumulation of positive charge in the primary irradiation area as expected from earlier work...
January 31, 2018: Ultramicroscopy
Li-Juan Pang, Jiang-Tao Hu, Mao-Jiang Zhang, Chen-Guang Yang, Guo-Zhong Wu
A novel quaternary ammonium polyethylene nonwoven fabric for removing chromium ions from water was prepared via radiation-induced grafting of glycidyl methacrylate and further modification with N,N'-dimethylethylenediamine. The structural and morphological characteristics of the adsorbent were analyzed using Fourier transform infrared spectroscopy (FTIR), thermogravimetry and differential thermogravimetry (TG/DTG), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The influences of several principal factors, including pH value, initial Cr(VI) concentration, contact time, and coexisting anions (including SO42-, CO32-, NO3-, PO43-, and Cl-), on adsorption performance were investigated via batch tests...
February 6, 2018: Environmental Science and Pollution Research International
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