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https://www.readbyqxmd.com/read/28651318/fate-of-polycyclic-aromatic-hydrocarbons-from-the-north-pacific-to-the-arctic-field-measurements-and-fugacity-model-simulation
#1
Hongwei Ke, Mian Chen, Mengyang Liu, Meng Chen, Mengshan Duan, Peng Huang, Jiajun Hong, Yan Lin, Shayen Cheng, Xuran Wang, Mengxue Huang, Minggang Cai
Polycyclic aromatic hydrocarbons (PAHs) have accumulated ubiquitously inArctic environments, where re-volatilization of certain organic pollutants as a result of climate change has been observed. To investigate the fate of semivolatile organic compounds in the Arctic, dissolved PAHs in the surface seawaters from the temperate Pacific Ocean to the Arctic Ocean, as well as a water column in the Arctic Ocean, were collected during the 4th Chinese National Arctic Research Expedition in summer 2010. The total concentrations of seven dissolved PAHs in surface water ranged from 1...
June 16, 2017: Chemosphere
https://www.readbyqxmd.com/read/28651056/significantly-improved-protein-folding-thermodynamics-using-a-dispersion-corrected-water-model-and-a-new-residue-specific-force-field
#2
Hao-Nan Wu, Fan Jiang, Yun-Dong Wu
An accurate potential energy model is crucial for biomolecular simulations. Despite many recent improvements of classical protein force fields, there are remaining key issues: much weaker temperature-dependence of folding/unfolding equilibrium, and overly collapsed unfolded or disordered states. For the later problem, a new water model (TIP4P-D) has been proposed to correct the significantly underestimated water dispersion interactions. Here, using TIP4P-D, we reveal problems in current force fields through failures in folding model systems (a polyalanine peptide, Trp-cage and the GB1 hairpin)...
June 26, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28647285/contrasting-patterns-of-energy-metabolism-in-northern-vs-southern-peripheral-european-flounder-populations-exposed-to-temperature-rising-and-hypoxia
#3
Nicolas Pédron, Jessy Le Du, Grégory Charrier, José-Luis Zambonino-Infante, Nicolas Le Bayon, Rita P Vasconcelos, Vanessa F Fonseca, Fabienne Le Grand, Jean Laroche
A two months common garden experiment was carried out to explore the potential differences of energy metabolism in northern core (France, 50°N and 47°N) vs southern peripheral (Portugal, 41°N) populations of European flounder Platichthys flesus, submitted to cold condition (CC: water temperature = 10 °C) and to warm and hypoxic condition (WHC: water temperature = 22 °C, and moderate hypoxia with O2 saturation = 40% during the last 6 days). Convergent growth rates (in length) were observed in the different populations and conditions, when the southern peripheral population of Portugal did not grow under cold conditions...
June 15, 2017: Marine Environmental Research
https://www.readbyqxmd.com/read/28647261/removal-of-ammonium-ion-from-water-by-na-rich-birnessite-performance-and-mechanisms
#4
Ya Cheng, Tinglin Huang, Xinxin Shi, Gang Wen, Yuankui Sun
Na-rich birnessite (NRB) was synthesized by a simple synthesis method and used as a high-efficiency adsorbent for the removal of ammonium ion (NH4(+)) from aqueous solution. In order to demonstrate the adsorption performance of the synthesized material, the effects of contact time, pH, initial ammonium ion concentration, and temperature were investigated. Adsorption kinetics showed that the adsorption behavior followed the pseudo second-order kinetic model. The equilibrium adsorption data were fitted to Langmuir and Freundlich adsorption models and the model parameters were evaluated...
July 2017: Journal of Environmental Sciences (China)
https://www.readbyqxmd.com/read/28646311/removal-of-arsenic-iii-v-by-a-granular-mn-oxide-doped-al-oxide-adsorbent-surface-characterization-and-performance
#5
Kun Wu, Jin Zhang, Bing Chang, Ting Liu, Furong Zhang, Pengkang Jin, Wendong Wang, Xiaochang Wang
In order to remove arsenic (As) from contaminated water, granular Mn-oxide-doped Al oxide (GMAO) was fabricated using the compression method with the addition of organic binder. The analysis results of XRD, SEM, and BET indicated that GMAO was microporous with a large specific surface area of 54.26 m(2/)g, and it was formed through the aggregation of massive Al/Mn oxide nanoparticles with an amorphous pattern. EDX, mapping, FTIR, and XPS results showed the uniform distribution of Al/Mn elements and numerous hydroxyl groups on the adsorbent surface...
June 23, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28645697/clinical-high-resolution-mapping-of-the-proteoglycan-bound-water-fraction-in-articular-cartilage-of-the-human-knee-joint
#6
Mustapha Bouhrara, David A Reiter, Kyle W Sexton, Christopher M Bergeron, Linda M Zukley, Richard G Spencer
PURPOSE: We applied a recently introduced method to achieve clinically-feasible in-vivo mapping of the proteoglycan water fraction (PgWF) of human knee cartilage with improved spatial resolution and stability as compared to existing methods. MATERIAL AND METHODS: Multicomponent driven equilibrium single-pulse observation of T1 and T2 (mcDESPOT) datasets were acquired from the knees of two healthy young subjects and one older subject with previous knee injury. Each dataset was processed using Bayesian Monte Carlo (BMC) analysis incorporating a two-component tissue model...
June 20, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28645057/effects-of-salinity-and-short-term-elevated-atmospheric-co2-on-the-chemical-equilibrium-between-co2-fixation-and-photosynthetic-electron-transport-of-stevia-rebaudiana-bertoni
#7
Sayed Hussin, Nicole Geissler, Mervat M M El-Far, Hans-Werner Koyro
The effect of water salinity on plant growth and photosynthetic traits of Stevia rebaudiana was investigated to determine its level and mechanisms of salinity tolerance. It was also attempted to assess how short-term elevated CO2 concentration would influence the boundaries and mechanisms of its photosynthetic capacity. The plants were grown in gravel/hydroponic system under controlled greenhouse conditions and irrigated with four different salinity levels (0, 25, 50 and 100 mol m(-3)NaCl). Low salinity did not significantly alter the plant fresh weight, which was substantially decreased by 67% at high salinity treatment...
June 15, 2017: Plant Physiology and Biochemistry: PPB
https://www.readbyqxmd.com/read/28644023/kinetics-of-interlayer-expansion-of-a-layered-silicate-driven-by-caffeine-intercalation-in-the-water-phase-using-transmission-x-ray-diffraction
#8
Tomohiko Okada, Takumi Yoshida, Taku Iiyama
The kinetics of caffeine uptake into the interlayer nanospace of silicate nanosheets modified with benzylammonium was evaluated by in situ monitoring the basal spacing in aqueous media using transmission X-ray diffraction. An interlayer spacing of 0.58 nm in water before caffeine uptake indicates a monomolecular layer of benzylammonium and a few water layers in each interlayer. The interlayer space expanded by 0.10 nm upon caffeine uptake (intercalation) and saturated even in the presence of excess caffeine...
June 23, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28643782/group-additivity-pourbaix-diagrams-advocate-thermodynamically-stable-nanoscale-clusters-in-aqueous-environments
#9
Lindsay A Wills, Xiaohui Qu, I-Ya Chang, Thomas J L Mustard, Douglas A Keszler, Kristin A Persson, Paul Ha-Yeon Cheong
The characterization of water-based corrosion, geochemical, environmental and catalytic processes rely on the accurate depiction of stable phases in a water environment. The process is aided by Pourbaix diagrams, which map the equilibrium solid and solution phases under varying conditions of pH and electrochemical potential. Recently, metastable or possibly stable nanometric aqueous clusters have been proposed as intermediate species in non-classical nucleation processes. Herein, we describe a Group Additivity approach to obtain Pourbaix diagrams with full consideration of multimeric cluster speciation from computations...
June 15, 2017: Nature Communications
https://www.readbyqxmd.com/read/28643279/highly-efficient-biosorptive-removal-of-lead-from-industrial-effluent
#10
Kajal Sao, Madhurima Pandey, Piyush Kant Pandey, Fahmida Khan
This study has been focused on the efficient removal of Pb (II) from contaminated waters by biosorption using plant derived material. Accordingly an indigenous shrub, Tinospora cordifolia has been identified as the most suitable biosorbent. The plant biomass was subjected to optimization of various parameters such as the pH, equilibrium time, dosage, concentration, temperature and the applicable adsorption models. The optimum pH identified was 4.0 with a contact time of 60 min at room temperature (27 ± 2 °C)...
June 22, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28642943/aqueous-dispersions-of-nanostructures-formed-through-the-self-assembly-of-iminolipids-with-exchangeable-hydrophobic-termini
#11
Wen Li, Daryl McManus, Han Liu, Cinzia Casiraghi, Simon J Webb
The addition of amines to an aldehyde surfactant, which was designed to be analogous to didodecyldimethylammonium bromide, gave exchangeable "iminolipids" that self-assembled to give stable aqueous dispersions of nano-sized vesicles. For example, sonication of suspensions of the n-hexylamine-derived iminolipid gave vesicles 50 to 200 nm in diameter that could encapsulate a water-soluble dye. The iminolipids could undergo dynamic exchange with added amines, and the resulting equilibrium constants (Krel) were quantified by (1)H NMR spectroscopy...
June 23, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28642235/atomic-layered-au-clusters-on-%C3%AE-moc-as-catalysts-for-the-low-temperature-water-gas-shift-reaction
#12
Siyu Yao, Xiao Zhang, Wu Zhou, Rui Gao, Wenqian Xu, Yifan Ye, Lili Lin, Xiaodong Wen, Ping Liu, Bingbing Chen, Ethan Crumlin, Jinghua Guo, Zhijun Zuo, Weizhen Li, Jinglin Xie, Li Lu, Christopher J Kiely, Lin Gu, Chuan Shi, José A Rodriguez, Ding Ma
The water-gas shift (WGS) reaction (CO+H2O=H2+CO2) is an essential process for hydrogen generation and CO removal in various energy-related chemical operations. This equilibrium-limited reaction is favored at a low working temperature. Potential application in fuel cells also requires a WGS catalyst to be highly active, stable and energy-efficient and match the working temperature of on-site hydrogen generation and consumption units. We synthesized Au layered clusters on an α-MoC substrate to create an interfacial catalyst system for the ultra-low-temperature WGS reaction...
June 22, 2017: Science
https://www.readbyqxmd.com/read/28642041/interaction-of-polyhedral-oligomeric-silsesquioxanes-and-dipalmitoylphosphatidylcholine-at-the-air-water-interface-thermodynamic-and-rheological-study
#13
M Skrzypiec, G As Georgiev, M Rojewska, K Prochaska
Polyhedral oligomeric silsesquioxanes (POSS) derivatives containing open silsesquioxane cage bear great potential for biomedical applications and therefore their lateral interactions with phospholipids, major biomembranes and drug vehicles constituent, should be studied in detail. That is why the properties of surface films by two POSS-derivatives, POSS-polyethylene glycol (POSS-PEG) and POSS-perfluoroalkyl (POSS-OFP), pure and in presence of 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine (DPPC) were studied using Langmuir surface balance...
June 19, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28640319/observational-constraints-on-particle-acidity-using-measurements-and-modelling-of-particles-and-gases
#14
J G Murphy, P K Gregoire, A G Tevlin, G R Wentworth, R A Ellis, M Z Markovic, T C VandenBoer
In many parts of the world, the implementation of air quality regulations has led to significant decreases in SO2 emissions with minimal impact on NH3 emissions. In Canada and the United States, the molar ratio of NH3 : SO2 emissions has increased dramatically between 1990 and 2014. In many regions of North America, this will lead the molar ratio of NHx : SO4, where NHx is the sum of particle phase NH4(+) and gas phase NH3, and SO4 is the sum of particle phase HSO4(-) and SO4(2-), to exceed 2. A thermodynamic model (E-AIM model II) is used to investigate the sensitivity of particle pH, and the gas-particle partitioning of NHx and inorganic nitrate, to the atmospheric NHx : SO4 ratio...
June 22, 2017: Faraday Discussions
https://www.readbyqxmd.com/read/28636330/water-in-ionic-liquid-lubricants-friend-and-foe
#15
Oscar Y Fajardo, Fernando Bresme, Alexei A Kornyshev, Michael Urbakh
To a greater or lesser extent, most room-temperature ionic liquids (RTILs) absorb water from humid air. Penetration of water into the lubricating nanoscale film may affect its equilibrium structure and dynamic properties and thus influence the ability of RTILs as lubricants to reduce friction between solid surfaces. Here we investigate the impact of hydration on lubrication using nonequilibrium molecular dynamics simulations. Water adsorption changes both the ionic liquid molecules' orientation and the slip conditions at the solid-liquid interfaces, resulting in a reduced resistance against squeezing-out of the lubricant by an external load...
June 26, 2017: ACS Nano
https://www.readbyqxmd.com/read/28634799/assessment-of-heat-inactivated-marine-aspergillus-flavus-as-a-novel-biosorbent-for-removal-of-cd-ii-hg-ii-and-pb-ii-from-water
#16
Mohamed E Mahmoud, Gehan M El Zokm, Aida E M Farag, Mohamed S Abdelwahab
A novel marine fungus was isolated and classified as Aspergillus flavus strain EGY11. The heat-inactivated form of isolated Aspergillus flavus was investigated and evaluated as a new eco-friendly and highly efficient biosorbent for removal of toxic heavy metals such as Cd(II), Hg(II), and Pb(II) from aqueous solutions. The SEM morphological studies of biosorbent-loaded metal ions confirmed their direct binding on the surface of heat-inactivated Aspergillus flavus. The metal biosorption capacity values were determined and optimized by the batch technique in the presence of various experimental controlling factors such as pH, contact time, biosorbent dosage, initial metal ion concentration, and coexisting species...
June 20, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28632908/prediction-of-groundwater-quality-trends-resulting-from-anthropogenic-changes-in-southeast-florida
#17
Quanghee Yi, Mark Stewart
The effects of surface water flow system changes caused by constructing water-conservation areas and canals in southeast Florida on groundwater quality under the Atlantic Coastal Ridge was investigated with numerical modeling. Water quality data were used to delineate a zone of groundwater with low total dissolved solids (TDS) within the Biscayne aquifer under the ridge. The delineated zone has the following characteristics. Its location generally coincides with an area where the Biscayne aquifer has high transmissivities, corresponds to a high recharge area of the ridge, and underlies a part of the groundwater mound formed under the ridge prior to completion of the canals...
June 20, 2017: Ground Water
https://www.readbyqxmd.com/read/28629065/preparation-and-characterization-of-in-situ-chitosan-polyethylene-glycol-fumarate-thymol-hydrogel-as-an-effective-wound-dressing
#18
Sepideh Koosehgol, Mehdi Ebrahimian-Hosseinabadi, Mehdi Alizadeh, Ali Zamanian
In the present study, polyethylene glycol fumarate (PEGF) was synthesized as a component of blend solutions via polycondensation polymerization and characterized by different tests in order to determine its functional groups and its physical properties included melting and crystallization temperature, enthalpy of fusion and average molecular weights. Wound dressing films based on chitosan (Ch), PEGF and thymol (Th) were fabricated by solvent casting method with different formulations contained 80%(w/w) chitosan and 20%(w/w) PEGF as polymeric components and different amounts of thymol consisted of 0, 0...
October 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28628873/complexation-thermodynamics-of-%C3%AE-cyclodextrin-with-ionic-surfactants-in-water
#19
Daniel Ondo, Miguel Costas
The interaction of α-cyclodextrin (α-CD) with ten ionic surfactants (S) in water was systematically examined using isothermal titration calorimetry. The S comprised cationic and anionic head groups while the hydrocarbon alkyl chain length varied from eight to fourteen carbon atoms. The heat data were measured at five temperatures ranging from 283.15K to 318.15K and were treated simultaneously allowing the estimation of a thermodynamically consistent temperature dependence of the equilibrium constant, as well as the enthalpy and heat capacity for the sequential formation of the [α-CD·S] and the [α-CD2·S] inclusion complexes...
June 8, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28627456/effect-of-the-surface-layer-on-drug-release-from-delefilcon-a-dailies-total1-%C3%A2-contact-lenses
#20
Phillip Dixon, Anuj Chauhan
Contact lenses are receiving significant attention for delivering ophthalmic drugs with higher bioavailability compared to eye drops. Here we explore drug transport from delefilcon-A Dailies Total1(®) lenses which are designed to have a thin, high-water content layer on the surface. Our goal is to determine the impact of this high water content layer on drug transport for both hydrophobic (dexamethasone and cyclosporine) and hydrophilic (timolol and levofloxacin) drugs. Drugs were loaded into the lens by soaking in aqueous drug solutions till equilibrium, followed by release in phosphate buffered saline...
June 13, 2017: International Journal of Pharmaceutics
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