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partition coefficient

Sook-Jin Kim, Hwajin Shin, Yong-Bok Lee, Hea-Young Cho
Perfluorohexanesulfonate (PFHxS), which belongs to the group of perfluoroalkyl and polyfluoroalkyl substances (PFASs), has been extensively used in industry and subsequently detected in the environment. Its use may be problematic, as PFHxS is known to induce neuronal cell death, and has been associated with early onset menopause in women and with attention deficit/hyperactivity disorder. Due to these impending issues, the aim of this study is to develop and evaluate a physiologically based pharmacokinetic (PBPK) model for PFHxS in male and female rats, and apply this to a human health risk assessment...
November 16, 2017: Archives of Toxicology
Haifeng Sun, Ruijie Feng, Yanli Nan, Zhang Chen, Nan Sang
To further assess the human being's exposure to polycyclic aromatic hydrocarbons (PAHs) through the dietary pathway, understanding the partitioning of these chemicals co-existed with nanomaterials in edible vegetable systems deserves specific consideration. In this study, the fiber-optic fluorimetry was applied to in situ examine the effects of graphene (GNS) and graphene oxide (GO) nanosheets on the quantification and depuration of three-ringed phenanthrene (Phe) and four-ringed fluoranthene (Fla) adsorbed individually onto the living spinach (Spinacia oleracea L...
November 11, 2017: Environmental Pollution
Raj B Patel, Samuel H Yalkowsky
The rule of unity is based on a simple absorption parameter, Π, that can accurately predict whether or not an orally administered drug will be well absorbed or poorly absorbed. The intrinsic aqueous solubility and octanol-water partition coefficient, along with the drug dose are used to calculate Π. We show that a single delineator value for Π exist that can distinguish whether a drug is likely to be well absorbed (FA ≥ 0.5) or poorly absorbed (FA < 0.5) at any specified dose. The model is shown to give 82...
November 11, 2017: Biopharmaceutics & Drug Disposition
Rania Fourati, Marc Tedetti, Catherine Guigue, Madeleine Goutx, Hatem Zaghden, Sami Sayadi, Boubaker Elleuch
Particulate-bound aliphatic and polycyclic aromatic hydrocarbons (AHs and PAHs) were investigated in the surface waters of the Gulf of Gabès (Tunisia, southern Mediterranean Sea). Samples were collected off the Sfax and Gabès-Ghannouch coasts. Concentrations in total resolved n-alkanes ranged from 0.03 to 3.2 μg L(-1), and concentrations in total parents + alkylated PAHs ranged from bdl to 108.6 ng L(-1). The highest concentrations were recorded in the southern Sfax. AHs were mainly of biogenic origin with odd n-alkane predominance, although an anthropogenic contribution was also detected...
November 10, 2017: Environmental Science and Pollution Research International
Andreas Mecklenfeld, Gabriele Raabe
The calculation of solvation free energies ΔGsolv by molecular simulations is of great interest as they are linked to other physical properties such as relative solubility, partition coefficient, and activity coefficient. However, shortcomings in molecular models can lead to ΔGsolv deviations from experimental data. Various studies have demonstrated the impact of partial charges on free energy results. Consequently, calculation methods for partial charges aimed at more accurate ΔGsolv predictions are the subject of various studies in the literature...
November 10, 2017: Journal of Chemical Theory and Computation
Zhen Zhang, Fang Liu, Caian He, Yueli Yu, Min Wang
Application of an aqueous two-phase system (ATPS) coupled with ultrasonic technology for the extraction of phloridzin from Malus micromalus Makino was evaluated and optimized by response surface methodology (RSM). The ethanol/ammonium sulfate ATPS was selected for detailed investigation, including the phase diagram, effect of phase composition and extract conditions on the partition of phloridzin, and the recycling of ammonium sulfate. In addition, the evaluation of extraction efficiency and the identification of phloridzin were investigated...
November 10, 2017: Journal of Food Science
Patrick D Sinko, David Gidley, Richard Vallery, Aaron Lamoureux, Gordon L Amidon, Gregory E Amidon
The potential use of poly(dimethyl siloxane) (PDMS) as an in vitro biomimetic analogue of the passive drug absorption process in the human gastrointestinal tract (GI) is assessed. PDMS is biomimetic because of similarities in small molecule transport such as mechanism, ionization selectivity, lipophilicity. Nine molecular probes are used to evaluate the transport pathways and properties used to predict human oral absorption rates. The transport pathways through PDMS (bulk/pore) are analogous to transcellular (TCDT) and paracellular (PCDT) drug transport pathways...
November 9, 2017: Molecular Pharmaceutics
Miki Sato, Yuki Maeda, Toshio Ishioka, Akira Harata
The detection limits and photoionization thresholds of polycyclic aromatic hydrocarbons and their chlorides and nitrides on the water surface are examined using laser two-photon ionization and single-photon ionization, respectively. The laser two-photon ionization methods are highly surface-selective, with a high sensitivity for aromatic hydrocarbons tending to accumulate on the water surface in the natural environment due to their highly hydrophobic nature. The dependence of the detection limits of target aromatic molecules on their physicochemical properties (photoionization thresholds relating to excess energy, molar absorptivity, and the octanol-water partition coefficient) is discussed...
November 8, 2017: Analyst
Peter C Austin, Henrik Stryhn, George Leckie, Juan Merlo
Multilevel data occur frequently in many research areas like health services research and epidemiology. A suitable way to analyze such data is through the use of multilevel regression models. These models incorporate cluster-specific random effects that allow one to partition the total variation in the outcome into between-cluster variation and between-individual variation. The magnitude of the effect of clustering provides a measure of the general contextual effect. When outcomes are binary or time-to-event in nature, the general contextual effect can be quantified by measures of heterogeneity like the median odds ratio or the median hazard ratio, respectively, which can be calculated from a multilevel regression model...
November 8, 2017: Statistics in Medicine
Gang Tang, Baitao Wang, Guanglong Ding, Wenbing Zhang, You Liang, Chen Fan, Hongqiang Dong, Jiale Yang, Dandan Kong, Yongsong Cao
As a widely used herbicide, picloram has been frequently detected in the aquatic environment due to its high leaching potential and low adsorption by soil. To reduce aquatic environmental risk of this herbicide caused by leaching and runoff, five herbicidal ionic liquids (HILs) based on picloram were prepared by pairing isopropylamine, octylamine, octadecylamine, 1-methylimidazole, 4-methylmorpholine respectively. Their physicochemical properties including water solubility, octanol-water partition coefficient, surface activity, leaching, as well as soil adsorption were compared...
November 4, 2017: Science of the Total Environment
K C Papadaki, S P Karakitsios, D A Sarigiannis
A Quantitative Structure Activity Relationship (QSAR) model was developed in order to predict the adipose/blood partition coefficient of environmental chemical compounds. The first step of QSAR modeling was the collection of inputs. Input data included the experimental values of adipose/blood partition coefficient and two sets of molecular descriptors for 67 organic chemical compounds; a) the descriptors from Linear Free Energy Relationship (LFER) and b) the PaDEL descriptors. The datasets were split to training and prediction set and were analysed using two statistical methods; Genetic Algorithm based Multiple Linear Regression (GA-MLR) and Artificial Neural Networks (ANN)...
October 31, 2017: Food and Chemical Toxicology
Ishwar Chandra Yadav, Ningombam Linthoingambi Devi, Jun Li, Gan Zhang
While various investigations have been driven on polybrominated diphenyl ethers (PBDEs) and other flame retardants (FRs) in different framework around the world, information about contamination and fate of PBDEs and other FRs in developing countries especially in the Indian subcontinent is uncommon. Nepal being located in the Indian subcontinent, very little is known about contamination level of semi-volatile organic pollutants discharged into the environment. This motivated us to investigate the environmental fate of halogenated flame retardant (HFRs) in Nepalese condition...
November 3, 2017: Environmental Pollution
Lingyi Li, Senpei Yang, Tao Chen, Lujia Han, Guoping Lian
OBJECTIVE: In the process of hair treatment, various cationic actives contained in hair care products can be absorbed into hair fiber to modulate the physicochemical properties of hair such as color, strength, style and volume. There have been very limited studies on the binding and partition properties of hair care actives to hair. This study aimed to investigate the pH effects on cationic solute absorption into hair and binding to keratin. METHODS: The keratin binding and hair partition properties of three cationic solutes (theophylline, nortriptyline and amitriptyline) have been measured at different pH using fluorescence spectroscopy and equilibrium absorption experiment...
November 6, 2017: International Journal of Cosmetic Science
Juan-Ying Li, Wenxuan Shi, Zhenhua Li, Yiqin Chen, Liu Shao, Ling Jin
Mariculture product safety in relation to sediment quality has attracted increasing attention because of the accumulation of potentially hazardous chemicals, including pyrethroid insecticides, in sediment. Passive sampling has been widely used to assess the bioavailability of sediment-associated hydrophobic organic contaminants and predict their body residue in benthic organisms. Therefore, in this study, we introduced polydimethylsiloxane (PDMS) polymer as a biomimetic "chemometer" for freely-dissolved concentrations (Cfree) to assess the efficacy of different carbon sorbents in reducing the bioavailability of pyrethroids in the process of sediment remediation...
November 2, 2017: Science of the Total Environment
Chao Liang, Jun-Qin Qiao, Hong-Zhen Lian
Reversed-phase liquid chromatography (RPLC) based octanol-water partition coefficient (logP) or distribution coefficient (logD) determination methods were revisited and assessed comprehensively. Classic isocratic and some gradient RPLC methods were conducted and evaluated for neutral, weak acid and basic compounds. Different lipophilicity indexes in logP or logD determination were discussed in detail, including the retention factor logkw corresponding to neat water as mobile phase extrapolated via linear solvent strength (LSS) model from isocratic runs and calculated with software from gradient runs, the chromatographic hydrophobicity index (CHI), apparent gradient capacity factor (kg') and gradient retention time (tg)...
October 27, 2017: Journal of Chromatography. A
May S Freag, Wedad M Saleh, Ossama Y Abdallah
Celastrol (CST) is a promising natural drug of herbal origin that gained a great interest in the recent years by virtue of its wide variety of pharmacological actions. Nowadays, CST is extensively studied as a natural anticancer surrogate with a potential activity against various types of cancers. However, CST suffers from many limitations that handicapped its clinical utility such as limited aqueous solubility and poor gastrointestinal absorption which resulted into its low oral bioavailability. This work spotlights, for the first time, development of self-assembled phytosomal nanocarriers (CST-PHY) for improving CST solubility and oral bioavailability...
November 2, 2017: International Journal of Pharmaceutics
Pau San-Valero, Antonio D Dorado, Guillermo Quijano, F Javier Álvarez-Hornos, Carmen Gabaldón
A dynamic model describing styrene abatement was developed for a two-phase partitioning bioreactor operated as a biotrickling filter (TPPB-BTF). The model was built as a coupled set of two different systems of partial differential equations depending on whether an irrigation or a non-irrigation period was simulated. The maximum growth rate was previously calibrated from a conventional BTF treating styrene (Part 1). The model was extended to simulate the TPPB-BTF based on the hypothesis that the main change associated with the non-aqueous phase is the modification of the pollutant properties in the liquid phase...
October 27, 2017: Chemosphere
M Farokhzadi, A Maleki, A Fallah, S Rashidi
Estimating the elbow angle using shoulder data is very important and valuable in Functional Electrical Stimulation (FES) systems which can be useful in assisting C5/C6 SCI patients. Much research has been conducted based on the elbow-shoulder synergies. The aim of this study was the online estimation of elbow flexion/extension angle from the upper arm acceleration signals during ADLs. For this, a three-level hierarchical structure was proposed based on a new approach, i.e. 'the movement phases'. These levels include Clustering, Recognition using HMMs and Angle estimation using neural networks...
September 2017: Journal of Biomedical Physics & Engineering
Shivani Kumar, Suman Chowdhury, Suresh Kumar
BACKGROUND: Alzheimer's disease (AD) is the most prevalent form of dementia and represents one of the highest unmet requirements in medicine today. There is shortage of novel molecules entering into market because of poor pharmacokinetic properties and safety issues. Drug repurposing offers an opportunity to reinvigorate the slowing drug discovery process by finding new uses for existing drugs. The major advantage of the drug repurposing approach is that the safety issues are already investigated in the clinical trials and the drugs are commercially available in the marketplace...
October 27, 2017: BMC Neuroscience
Kirsten Rasmussen, Hubert Rauscher, Agnieszka Mech, Juan Riego Sintes, Douglas Gilliland, Mar González, Peter Kearns, Kenneth Moss, Maaike Visser, Monique Groenewold, Eric A J Bleeker
Identifying and characterising nanomaterials require additional information on physico-chemical properties and test methods, compared to chemicals in general. Furthermore, regulatory decisions for chemicals are usually based upon certain toxicological properties, and these effects may not be equivalent to those for nanomaterials. However, regulatory agencies lack an authoritative decision framework for nanomaterials that links the relevance of certain physico-chemical endpoints to toxicological effects. This paper investigates various physico-chemical endpoints and available test methods that could be used to produce such a decision framework for nanomaterials...
October 23, 2017: Regulatory Toxicology and Pharmacology: RTP
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