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https://www.readbyqxmd.com/read/28737791/aqueous-ionic-liquids-and-their-influence-on-peptide-conformations-denaturation-and-dehydration-mechanisms
#1
Diddo Diddens, Volker Lesch, Andreas Heuer, Jens Smiatek
Low concentrated aqueous ionic liquids (ILs) and their influence on protein structures have attracted a lot of interest over the last few years. This can be mostly attributed to the fact that aqueous ILs, depending on the ion species involved, can be used as protein protectants or protein denaturants. Atomistic molecular dynamics (MD) simulations are performed in order to study the influence of different aprotic ILs on the properties of a short hairpin peptide. Our results reveal distinct binding and denaturation effects for 1-ethyl-3-methylimidazolium (EMIM) in combination with different anions, namely, chloride (CL), tetrafluoroborate (BF4) and acetate (ACE)...
July 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28733822/concentrations-and-inhalation-risk-assessment-of-short-chain-polychlorinated-paraffins-in-the-urban-air-of-dalian-china
#2
Xiuhua Zhu, Hao Bai, Yuan Gao, Jiping Chen, Heping Yuan, Longxing Wang, Wei Wang, Xuewei Dong, Xiaoxiao Li
The concentrations of short-chain polychlorinated paraffins (SCCPs) in the urban air of Dalian, China, were monitored from March to October 2010 and from September to October 2016 with active high-volume sampler. The total concentration of SCCPs (particulate phase + gas phase) ranged from 15.12 to 66.44 ng m(-3), with an average of 30.26 ng m(-3) in 2010, and 65.30 to 91.00 ng m(-3), with an average of 78.15 ng m(-3) in 2016. Hexa-chlorinated dodecane and hexa-chlorinated undecane are the predominant components in the gas phase, while octa-chlorinated undecane and hepta-chlorinated tridecane are dominant in the particulate phase...
July 22, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28733617/partitioning-evapotranspiration-into-green-and-blue-water-sources-in-the-conterminous-united-states
#3
Naga Manohar Velpuri, Gabriel B Senay
In this study, we combined two 1 km actual evapotranspiration datasets (ET), one obtained from a root zone water balance model and another from an energy balance model, to partition annual ET into green (rainfall-based) and blue (surface water/groundwater) sources. Time series maps of green water ET (GWET) and blue water ET (BWET) are produced for the conterminous United States (CONUS) over 2001-2015. Our results indicate that average green and blue water for all land cover types in CONUS accounts for nearly 70% and 30% of the total ET, respectively...
July 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28732396/role-of-dams-in-the-phase-transfer-of-antibiotics-in-an-urban-river-receiving-wastewater-treatment-plant-effluent
#4
Xiaoyu Guo, Chenghong Feng, Jianhong Zhang, Chenhao Tian, Jingling Liu
Dams are universally constructed to change hydrodynamic forces and impound water in urban rivers, but few efforts have been made to expound the impact of dams on the transport of antibiotics in rivers. In this study, the main object and focus was to elucidate the intercept effect of rubber dam and the gate dam on the sediment-water phase redistribution of eight typical antibiotics along an urban river with the water replenished from wastewater treatment plants (WWTPs). The results show that the eight antibiotics were widely detected in the whole river segment, and the WWTPs were found to be the main sources...
July 17, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28732332/heavy-metal-partitioning-of-suspended-particulate-matter-water-and-sediment-water-in-the-yangtze-estuary
#5
Chenghong Feng, Xiaoyu Guo, Su Yin, Chenhao Tian, Yangyang Li, Zhenyao Shen
The partitioning of ten heavy metals (As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Sb, and Zn) between the water, suspended particulate matter (SPM), and sediments in seven channel sections during three hydrologic seasons in the Yangtze Estuary was comprehensively investigated. Special attention was paid to the role of tides, influential factors (concentrations of SPM and dissolved organic carbon, and particle size), and heavy metal speciation. The SPM-water and sediment-water partition coefficients (Kp) of the heavy metals exhibited similar changes along the channel sections, though the former were larger throughout the estuary...
July 17, 2017: Chemosphere
https://www.readbyqxmd.com/read/28729957/decline-of-heterozygosity-in-a-large-but-isolated-population-a-45-year-examination-of-moose-genetic-diversity-on-isle-royale
#6
Renae L Sattler, Janna R Willoughby, Bradley J Swanson
Wildlife conservation and management approaches typically focus on demographic measurements to assess population viability over both short and long periods. However, genetic diversity is an important predictor of long term population vitality. We investigated the pattern of change in genetic diversity in a large and likely isolated moose (Alces alces) population on Isle Royale (Lake Superior) from 1960-2005. We characterized samples, partitioned into five different 5-year periods, using nine microsatellite loci and a portion of the mtDNA control region...
2017: PeerJ
https://www.readbyqxmd.com/read/28728708/effect-of-partitioning-the-nonfiber-carbohydrate-fraction-and-neutral-detergent-fiber-method-on-digestibility-of-carbohydrates-by-dairy-cows
#7
A W Tebbe, M J Faulkner, W P Weiss
Many nutrition models rely on summative equations to estimate feed and diet energy concentrations. These models partition feed into nutrient fractions and multiply the fractions by their estimated true digestibility, and the digestible mass provided by each fraction is then summed and converted to an energy value. Nonfiber carbohydrate (NFC) is used in many models. Although it behaves as a nutritionally uniform fraction, it is a heterogeneous mixture of components. To reduce the heterogeneity, we partitioned NFC into starch and residual organic matter (ROM), which is calculated as 100 - CP - LCFA - ash - starch - NDF, where crude protein (CP), long-chain fatty acids (LCFA), ash, starch, and neutral detergent fiber (NDF) are a percentage of DM...
August 2017: Journal of Dairy Science
https://www.readbyqxmd.com/read/28727423/seasonal-variation-of-terrigenous-pahs-along-the-marginal-seas-of-china-input-phase-partitioning-ocean-current-transport
#8
Miao-Lei Ya, Xin-Hong Wang, Yu-Ling Wu, Yong-Yu Li, Jing-Ming Yan, Chao Fang, Yan-Yan Zhao, Ran-Ran Qian, Xiao-Long Lin
To study the spatial distributions and seasonal differences of concentrations, source identification, and phase partitioning of polycyclic aromatic hydrocarbons (PAHs) in the surface water, intensive sampling was carried out along the marginal seas of China in four seasons. In the northern South China Sea (SCS), the highest PAH levels occurred in summer (July to August) and autumn (October to November). In the East China Sea (ECS) and the Yellow Sea, the highest occurred in summer (August) and winter (December)...
July 20, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28722512/in-silico-and-in-vitro-evaluation-of-two-novel-oximes-k378-and-k727-in-comparison-to-k27-and-pralidoxime-against-paraoxon-ethyl-intoxication
#9
Maria Chaudhry, Muhammad Qaiser Fatmi, Kamil Musilek, Alamdar Hussain, Kamil Kuca, Georg Petroianu, Huba Kalasz, Syed Muhammad Nurulain
Organophosphate (OP) poisoning is a major global health issue; while compounds from this group have been used intensively over the last century, an effective antidote is still lacking. Oxime-type AChE reactivators are used to reactivate the OP inhibited AChE. Pralidoxime is the only US Food and Drug Administration, (FDA) approved oxime for therapeutic use but its efficacy has been disappointing. Two novel oximes (K378 and K727) were investigated in silico and in vitro and compared with an experimental oxime (kamiloxime; K-27) and pralidoxime...
July 19, 2017: Toxicology Mechanisms and Methods
https://www.readbyqxmd.com/read/28721420/adsorption-of-galloyl-catechin-aggregates-significantly-modulates-membrane-mechanics-in-the-absence-of-biochemical-cues
#10
Takahisa Matsuzaki, Hiroaki Ito, Veronika Chevyreva, Ali Makky, Stefan Kaufmann, Kazuki Okano, Naritaka Kobayashi, Masami Suganuma, Seiichiro Nakabayashi, Hiroshi Y Yoshikawa, Motomu Tanaka
Physical interactions of four major green tea catechin derivatives with cell membrane models were systemically investigated. Catechins with the galloyl moiety caused the aggregation of small unilamellar vesicles and an increase in the surface pressure of lipid monolayers, while those without did not. Differential scanning calorimetry revealed that, in a low concentration regime (≤10 μM), catechin molecules are not significantly incorporated into the hydrophobic core of lipid membranes as substitutional impurities...
July 19, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28721301/synthesis-and-characterization-of-n-mannich-based-prodrugs-of-ciprofloxacin-and-norfloxacin-in-vitro-anthelmintic-and-cytotoxic-evaluation
#11
Mona Piplani, Harish Rajak, Prabodh Chander Sharma
Prodrugs, the inert derivatives of existing drugs have successfully contributed to the modification of their physicochemical properties. The improved antimicrobial potential due to enhanced lipophilicity of some of the synthesized prodrugs of antibacterial agents by various schemes has already been reported. In the current study, synthesis, characterization, and biological evaluation of some more lipid based prodrugs/compounds of ciprofloxacin and norfloxacin has been carried out. The synthesized prodrugs/compounds have been screened for anthelmintic activity using Indian earthworms and cytotoxic activity against human lung cancer cell lines A-549 employing sulforhodamine B (SRB) assay method...
July 2017: Journal of Advanced Research
https://www.readbyqxmd.com/read/28720783/a-simple-robust-and-efficient-computational-method-for-n-octanol-water-partition-coefficients-of-substituted-aromatic-drugs
#12
Asrin Bahmani, Saadi Saaidpour, Amin Rostami
In this paper, multiple linear regression (MLR) was used to build quantitative structure property relationship (QSPR) of n-octanol-water partition coefficient (logPo/w) of 195 substituted aromatic drugs. The molecular descriptors were calculated for each compound by the VLifeMDS. By applying genetic algorithm/multiple linear regressions (GA/MLR) the most relevant descriptors were selected to build a QSPR model. The robustness of the model was characterized by the statistical validation and applicability domain (AD)...
July 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28718686/kinetic-study-on-the-inhibition-of-xanthine-oxidase-by-acylated-derivatives-of-flavonoids-synthesised-enzymatically
#13
Maria Elisa Melo Branco de Araújo, Yollanda Edwirges Moreira Franco, Thiago Grando Alberto, Marcia Cristina Fernandes Messias, Camila Wielewski Leme, Alexandra Christine Helena Frankland Sawaya, Patricia de Oliveira Carvalho
Studies have reported that flavonoids inhibit xanthine oxidase (XO) activity; however, poor solubility and stability in lipophilic media limit their bioavailability and applications. This study evaluated the kinetic parameters of XO inhibition and partition coefficients of flavonoid esters biosynthesised from hesperidin, naringin, and rutin via enzymatic acylation with hexanoic, octanoic, decanoic, lauric, and oleic acids catalysed by Candida antarctica lipase B (CALB). Quantitative determination by ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) showed higher conversion yields (%) for naringin and rutin esters using acyl donors with 8C and 10C...
December 2017: Journal of Enzyme Inhibition and Medicinal Chemistry
https://www.readbyqxmd.com/read/28718641/in-silico-skin-model-a-multiscale-simulation-study-of-drug-transport
#14
Kishore Gajula, Rakesh Gupta, D B Sridhar, Beena Rai
Accurate in-silico models are required to predict the release of drug molecules through skin in order to supplement the in-vivo experiments for faster development/testing of drugs. The upper most layer of the skin, stratum corneum (SC), offers main resistance for permeation of actives. Most of the SC's molecular level models comprise of cholesterol, and phospholipids only, which is far from the reality. In this study we have implemented a multiscale modelling framework to obtain the release profile of three drugs namely Caffeine, Fentanyl and Naphthol through skin SC...
July 18, 2017: Journal of Chemical Information and Modeling
https://www.readbyqxmd.com/read/28715771/a-flow-through-aqueous-standard-generation-system-for-thin-film-microextraction-investigations-of-uv-filters-and-biocides-partitioning-to-different-environmental-compartments
#15
Fardin Ahmadi, Chris Sparham, Janusz Pawliszyn
In this paper problems associated with preparation of aqueous standard of highly hydrophobic compounds such as partial precipitation, being lost on the surfaces, low solubility in water and limited sample volume for accurate determination of their distribution coefficients are addressed. The following work presents two approaches that utilize blade thin film microextraction (TFME) to investigate partitioning of UV filters and biocides to humic acid (dissolved organic carbon) and sediment. A steady-state concentration of target analytes in water was generated using a flow-through aqueous standard generation (ASG) system...
July 14, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28715012/the-properties-of-residual-water-molecules-in-ionic-liquids-a-comparison-between-direct-and-inverse-kirkwood-buff-approaches
#16
Takeshi Kobayashi, Joshua E S J Reid, Seishi Shimizu, Maria Fyta, Jens Smiatek
We study the properties of residual water molecules at different mole fractions in dialkylimidazolium based ionic liquids (ILs), namely 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM/BF4) and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM/BF4) by means of atomistic molecular dynamics (MD) simulations. The corresponding Kirkwood-Buff (KB) integrals for the water-ion and ion-ion correlation behavior are calculated by a direct evaluation of the radial distribution functions. The outcomes are compared to the corresponding KB integrals derived by an inverse approach based on experimental data...
July 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28712300/a-continuous-intestinal-absorption-model-based-on-the-convection-diffusion-equation
#17
Swati Nagar, Richard C Korzekwa, Ken Korzekwa
Prediction of the rate and extent of drug absorption upon oral dosing needs models that capture the complexities of both the drug molecule and intestinal physiology. We report here the development of a continuous intestinal absorption model based on the convection-diffusion equation. The model includes explicit enterocyte apical membrane and intracellular lipid radial compartments along the length of the intestine. Physiologic functions along length x are built into the model, and include velocity, diffusion, surface areas, and pH of the intestine...
July 17, 2017: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/28707900/aerosol-fragmentation-driven-by-coupling-of-acid-base-and-free-radical-chemistry-in-the-heterogeneous-oxidation-of-aqueous-citric-acid-by-oh-radicals
#18
Matthew J Liu, Aaron A Wiegel, Kevin R Wilson, Frances A Houle
A key uncertainty in the heterogeneous oxidation of carboxylic acids by hydroxyl radicals (OH) in aqueous phase aerosol is how the free radical reaction pathways might be altered by acid-base chemistry. In particular, if acid-base reactions occur concurrently with acyloxy radical formation and unimolecular decomposition of alkoxy radicals, there is a possibility that differences in reaction pathways impact the partitioning of organic carbon between the gas and aqueous phases. To examine these questions, a kinetic model is developed for the OH initiated oxidation of citric acid aerosol at high relative humidity...
July 14, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28704191/association-of-permeability-and-lipid-content-of-membrane
#19
Kalpesh C Ashara, Ketan V Shah
BACKGROUND: Rat skin and goat cul de sac are mostly used in optimization of formulations as the model of human skin and cul de sac. AIM: To explore the correlation between lipid content of rat skin and goat cul de sac and permeability. MATERIALS AND METHODS: Find out wavelength maximum for Sapat plus malam®, Ciplox eye ointment® and chloramphenicol eye caps and the standard curve was also derived. In vitro studies using Cellophane® membrane and ex vivo studies using rat skin or goat cul de sac of the formulations...
June 1, 2017: Folia Medica
https://www.readbyqxmd.com/read/28702652/explicit-consideration-of-spatial-hydrogen-bonding-direction-for-activity-coefficient-prediction-based-on-implicit-solvation-calculations
#20
Wei-Lin Chen, Shiang-Tai Lin
The activity coefficient of a chemical in a mixture is important in understanding the thermodynamic properties and non-ideality of the mixture. The COSMO-SAC model based on the result of quantum mechanical implicit solvation calculations has been shown to provide reliable predictions of activity coefficients for mixed fluids. However, it is found that the prediction accuracy is in general inferior for associating fluids. Existing methods for describing the hydrogen-bonding interaction consider the strength of the interaction based only on the polarity of the screening charges, neglecting the fact that the formation of hydrogen bonds requires a specific orientation between the donor and acceptor pairs...
July 12, 2017: Physical Chemistry Chemical Physics: PCCP
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