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partition coefficient

Philip J Williamson, Greg Atkinson, Alan M Batterham
It has recently been reported how to quantify inter-individual differences in the response to an exercise intervention using the standard deviation of the change scores, as well as how to appraise these differences for clinical relevance. In a parallel-group randomised controlled trial, the key trigger for further investigation into inter-individual responses is when the standard deviation of change in the intervention sample is substantially larger than the same standard deviation derived from a suitable comparator sample...
January 17, 2017: Sports Medicine
M L Wang, M Dzievit, Z Chen, J B Morris, J E Norris, N A Barkley, B Tonnis, G A Pederson, J Yu
Castor is an important oilseed crop and although its oil is inedible, it has multiple industrial and pharmaceutical applications. The entire US castor germplasm collection was previously screened for oil content and fatty acid composition, but its genetic diversity and population structure has not been determined. Based on the screening results of oil content, fatty acid composition, and country origins, 574 accessions were selected and genotyped with 22 polymorphic EST-SSR markers. The results from cluster analysis, population structure, and principal component analysis were consistent, and partitioned accessions into four subpopulations...
October 14, 2016: Genome Génome / Conseil National de Recherches Canada
Niell Silvina, Jesús Florencia, Pérez Nicolás, Pérez Cecilia, Pareja Lucía, Silvana Abbate, Carrasco-Letelier Leonidas, Díaz Sebastián, Mendoza Yamandú, Cesio Verónica, Heinzen Horacio
The beehive as a quantitative monitor of pesticide residues applied over a soybean crop was studied through a semi field experiment of controlled exposure of honey bees to pesticides in macro tunnels. The distribution within exposed beehives of pesticides commonly used in soybean plantation, was assessed. Residue levels of insecticides in soybean leaves, honey bees, wax, honey and pollen were analyzed. The transference from pesticides present in the environment into the beehive was evidenced. The obtained results allow relating pesticide concentrations present in the environment with traces found in foraging bees...
January 7, 2017: Science of the Total Environment
Jovan Kamcev, Donald R Paul, Gerald S Manning, Benny D Freeman
This study presents a framework for predicting salt permeability coefficients in ion exchange membranes in contact with an aqueous salt solution. The model, based on the solution-diffusion mechanism, was tested using experimental salt permeability data for a series of commercial ion exchange membranes. Equilibrium salt partition coefficients were calculated using a thermodynamic framework (i.e., Donnan theory), incorporating Manning's counter-ion condensation theory to calculate ion activity coefficients in the membrane phase and the Pitzer model to calculate ion activity coefficients in the solution phase...
January 10, 2017: ACS Applied Materials & Interfaces
Andrew K Matzen, Michael B Baker, John R Beckett, Bernard J Wood, Edward M Stolper
We report the results of experiments designed to separate the effects of temperature and pressure from liquid composition on the partitioning of Ni between olivine and liquid, [Formula: see text]. Experiments were performed from 1300 to 1600 °C and 1 atm to 3.0 GPa, using mid-ocean ridge basalt (MORB) glass surrounded by powdered olivine in graphite-Pt double capsules at high pressure and powdered MORB in crucibles fabricated from single crystals of San Carlos olivine at one atmosphere. In these experiments, pressure and temperature were varied in such a way that we produced a series of liquids, each with an approximately constant composition (~12, ~15, and ~21 wt% MgO)...
2017: Contributions to Mineralogy and Petrology. Beiträge Zur Mineralogie und Petrologie
Hassan Yousefnia, Razieh Enayati, Mohammad Hosntalab, Samaneh Zolghadri, Ali Bahrami-Samani
AIM: Various phosphonate ligands labeled with β--emitting radionuclides have shown good efficacy for bone pain palliation. In this study, a new agent for bone pain palliation has been developed. MATERIALS AND METHODS: Samarium-153-(4-[((bis(phosphonomethyl))carbamoyl)methyl]-7,10-bis (carboxymethyl)-1,4,7,10-tetraazacyclododec-1-yl) acetic acid (153Sm-BPAMD) complex was prepared using BPAMD ligand and samarium-153 chloride. The effect of various parameters on the labeling yield of 153Sm-BPAMD including ligand concentration, pH, temperature, and reaction time were studied...
July 2016: Journal of Cancer Research and Therapeutics
Nádia Melo Borges, Peter W Kenny, Carlos A Montanari, Igor M Prokopczyk, Jean F R Ribeiro, Josmar R Rocha, Geraldo Rodrigues Sartori
This Perspective explores how consideration of hydrogen bonding can be used to both predict and better understand partition coefficients. It is shown how polarity of both compounds and substructures can be estimated from measured alkane/water partition coefficients. When polarity is defined in this manner, hydrogen bond donors are typically less polar than hydrogen bond acceptors. Analysis of alkane/water partition coefficients in conjunction with molecular electrostatic potential calculations suggests that aromatic chloro substituents may be less lipophilic than is generally believed and that some of the effect of chloro-substitution stems from making the aromatic π-cloud less available to hydrogen bond donors...
January 4, 2017: Journal of Computer-aided Molecular Design
Zofia Tylutki, Sebastian Polak
In the field of cardiac drug efficacy and safety assessment, information on drug concentration in heart tissue is desirable. Because measuring drug concentrations in human cardiac tissue is challenging in healthy volunteers, mathematical models are used to cope with such limitations. With a goal of predicting drug concentration in cardiac tissue, we have developed a whole-body PBPK model consisting of seventeen perfusion-limited compartments. The proposed PBPK heart model consisted of four compartments: the epicardium, midmyocardium, endocardium, and pericardial fluid, and accounted for cardiac metabolism using CYP450...
January 4, 2017: Scientific Reports
M Jen, J Johnson, P Hou, H Liu
PURPOSE: Cerebral blood flow quantification in arterial spin labeling (ASL) MRI requires an estimate of the equilibrium magnetization of blood, which is often obtained by a set of proton density (PD) reference image. Normally, a constant blood-brain partition coefficient is assumed across the brain. However, this assumption may not be valid for brain lesions. This study aimed to evaluate the impact of lesion-related PD variations on ASL quantification in patients with brain tumors. METHODS: MR images for posttreatment evaluation of 42 patients with brain tumors were retrospectively analyzed...
June 2016: Medical Physics
J Nute, Y Zhou, A Scott, C Lee
PURPOSE: To establish a relationship between pixel noise and the statistically defined minimum detectable contrast for various phantom sizes in order to provide a means for dose modulation driven by the task-specific low contrast detectability. METHODS: Seven anthropomorphically-shaped abdomen phantoms (TE01-TE08, CIRS) were employed to mimic a wide range of patient sizes. Each phantom was scanned on a Siemens 64-slice mCT using a range of CTDIvol values (1-38mGy) with an average of 19 dose levels per phantom...
June 2016: Medical Physics
D Pinkham, M Negahdar, E Schueler, T Yamamoto, M Diehn, E Mittra, B Loo, P Maxim
PURPOSE: To demonstrate the efficacy of a novel functional lung imaging method that utilizes single-inhalation, single-energy xenon CT (Xe-CT) lung ventilation scans, and to compare it against the current clinical standard, ventilation single-photon emission CT (V-SPECT). METHODS: In an IRB-approved clinical study, 14 patients undergoing thoracic radiotherapy received two successive single inhalation, single energy (80keV) CT images of the entire lung using 100% oxygen and a 70%/30% xenon-oxygen mixture...
June 2016: Medical Physics
A Iacobino, G Piccaro, F Giannoni, A Mustazzolu, L Fattorini
OBJECTIVE/BACKGROUND: Heterogeneous mixtures of cellular and caseous granulomas coexist in the lungs of tuberculosis (TB) patients, with Mycobacterium tuberculosis (Mtb) existing from actively replicating (AR) to dormant, nonreplicating (NR) stages. Within cellular granulomas, the pH is estimated to be less than 6, whereas in the necrotic centres of hypoxic, cholesterol/triacylglycerol-rich, caseous granulomas, the pH varies between 7.2 and 7.4. To combat TB, we should kill both AR and NR stages of Mtb...
December 2016: International Journal of Mycobacteriology
Runxia Sun, Xiaojun Luo, Bin Tang, Laiguo Chen, Yu Liu, Bixian Mai
Short chain chlorinated paraffins (SCCPs) are under review for inclusion into the Stockholm Convention on Persistent Organic Pollutants. However, limited information is available on their bioaccumulation and biomagnification in ecosystems, which is hindering evaluation of their ecological and health risks. In the present study, wild aquatic organisms (fish and invertebrates), water, and sediment collected from an enclosed freshwater pond contaminated by electronic waste (e-waste) were analyzed to investigate the bioaccumulation, distribution, and trophic transfer of SCCPs in the aquatic ecosystem...
December 28, 2016: Environmental Pollution
Maneerat Ongwandee, Thabtim Chatsuvan, Wichitsawat Suksawas Na Ayudhya, John Morris
We studied adsorption of organic compounds to a wide range of indoor materials, including plastics, gypsum board, carpet, and many others, under various relative humidity conditions by applying a conceptual model of the free energy of interfacial interactions of both van der Waals and Lewis acid-base (e-donor/acceptor) types. Data used for the analyses were partitioning coefficients of adsorbates between surface and gas phase obtained from three sources: our sorption experiments and two other published studies...
December 30, 2016: Environmental Science and Pollution Research International
Boris Shekunov
A new theoretical approach combining convective diffusion and surface dissolution kinetics has been applied to micellar systems and tested on experimental data available for both rotating disk apparatus and particles. The micelles are shown to be in the state of dynamic equilibrium with solution for most systems but nanoparticles. For ionizable molecules, the variation of partition coefficient across diffusion boundary layer may affect the diffusivity. The intrinsic dissolution rate is generally a nonlinear function of the equilibrium concentration, c0, in which the diffusion kinetic coefficient, βD, surface kinetic coefficient, β0, and total kinetic coefficient of dissolution, β, all typically decrease as functions of c0 (or increasing micellar concentration, Mc)...
October 28, 2016: Journal of Pharmaceutical Sciences
Ken Korzekwa, Swati Nagar
Physiologically-based pharmacokinetic (PBPK) models explicitly incorporate tissue-specific blood flows, partition coefficients, and metabolic processes. Since PBPK models are derived using physiologic parameters and interactions of the compound with tissue components, these models are considered to be "bottom up" as opposed to "top down". Modeling approaches can be characterized as either a posteriori (observational) or a priori (based solely on theory). Furthermore, approaches can be mechanistic (structure and components based on mechanisms) or empirical (based on observations alone)...
December 27, 2016: Pharmaceutical Research
Yangxi Chu, Chak K Chan
Short-chain alkyl amines can undergo gas-to-particle partitioning via reactive uptake by ammonium salts, whose phases have been thought to largely influence the extent of amine uptake. Previous studies mainly focused on particles of single ammonium salt at either dry or wet conditions without any addition of organic compounds. Here we report the uptake of dimethylamine (DMA) by ammonium sulfate (AS) and AS-sucrose mixed particles at different relative humidities (RHs) using an electrodynamic balance coupled with in situ Raman spectroscopy...
December 27, 2016: Journal of Physical Chemistry. A
Rajneet Kaur Khurana, Arvind K Bansal, Sarwar Beg, Andrea Julie Burrow, O P Katare, Kamalinder K Singh, Bhupinder Singh
Mangiferin (Mgf), largely expressed out from the leaves and stem bark of Mango, is a potent antioxidant. However, its in vivo activity gets tremendously reduced owing to poor aqueous solubility and inconsistent gastrointestinal absorption, high hepatic first-pass metabolism and high P-gp efflux. The current research work, therefore, was undertaken to overcome the biopharmaceutical hiccups by developing the Mgf-phospholipid complex (PLCs) loaded in nanostructured lipidic carriers (NLCs). The PLCs and NLCs were prepared using refluxing, solvent evaporation and hot emulsification technique, respectively with three molar ratios of Mgf and Phospholipon 90G, i...
December 23, 2016: International Journal of Pharmaceutics
Xiaolan Zhang, Xiaojing Li, Ye Jing, Xiangming Fang, Xinyu Zhang, Bingli Lei, Yingxin Yu
Prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) is a high-priority public health concern. However, maternal to fetal transplacental transfer of PAHs has not been systematically studied. To investigate the transplacental transfer of PAHs from mother to fetus and determine the influence of lipophilicity (octanol-water partition coefficient, KOW) on transfer process, in the present study, we measured the concentrations of 15 PAHs in 95 paired maternal and umbilical cord serum, and placenta samples (in total 285 samples) collected in Shanghai, China...
December 23, 2016: Environmental Pollution
Guangcai Ma, Quan Yuan, Haiying Yu, Hongjun Lin, Jianrong Chen, Huachang Hong
The binding of organic chemicals to serum albumin can significantly reduce their unbound concentration in blood and affect their biological reactions. In this study, we developed a new QSAR model for bovine serum albumin (BSA) - water partition coefficients (KBSA/W) of neutral organic chemicals with large structural variance, logKBSA/W values covering 3.5 orders of magnitude (1.19-4.76). All chemical geometries were optimized by semi-empirical PM6 algorithm. Several quantum chemical parameters that reflect various intermolecular interactions as well as hydrophobicity were selected to develop QSAR model...
December 22, 2016: Ecotoxicology and Environmental Safety
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