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partition coefficient

Haiyang Feng, Yuping Zhu, Zhixuan Fu, Dechuan Li
In this study, rhein-SLNs were successfully produced by hot homogenization followed by ultrasonication. Precirol ATO5 in which Rhein exhibited higher partition coefficient was selected for preparation of SLNs. In the dynamic light scattering, the rhein SLNs showed a smaller size with a mean value of 120.8 ± 7.9 nm and with zeta potential of -16.9 ± 2.3 mV. SLNs exhibited a good stability during the period of 2 months. The SLNs indicated faster drug release with a burst release within 2 hours and followed by a sustained release with a biphasic drug release pattern...
April 22, 2017: Chemical Biology & Drug Design
Xochitli L Osorio Barajas, Maik A Jochmann, Thorsten Hüffer, Beat Schilling, Torsten C Schmidt
In-tube extraction is a full automated enrichment technique, which consists of a stainless-steel needle, packed with sorbent material for the extraction of volatile and semi-volatile compounds. In principle, all particulate sorbents used for enrichment in air or headspace analysis can be used. However, the selection of the sorbents is merely based on empirical considerations rather than on experimental data, which is caused by a lack of knowledge about the relevant physicochemical properties of the sorbent...
April 20, 2017: Journal of Separation Science
Doaa Alantary, Samuel Yalkowsky
The General Solubility Equation (GSE) is the state of the art method for estimating the aqueous solubilities of organic compounds. It is an extremely simple equation that expresses aqueous solubility as a function of only two inputs: the octanol-water partition coefficient calculated by readily available softwares like clogp and acdlogp, and the commonly known melting point of the solute. Recently, Bahadori, et al. (2016) proposed that their genetic algorithm support vector machine is a "better" predictor...
April 20, 2017: Pharmaceutical Development and Technology
Gregory T Sullivan, Sebahat K Ozman-Sullivan, Anne Bourne, Jean-Pierre Lumaret, Unal Zeybekoglu, Myron P Zalucki, Greg Baxter
Guilds of dung dwelling and tunneling dung beetles coexist in local assemblages in warm temperate regions, despite the tendency of dwellers to be inferior competitors. A field experiment on the Black Sea coast of Turkey examined the role of temporal resource partitioning in their coexistence. Standardized dung pads deposited at 4 h intervals through a 24 h period in summer were collected 12, 24, or 48 h later. Adults from 10 tunneling and seven dung dwelling species were collected. The tunnelers contributed a high proportion of both total abundance and biomass...
January 1, 2017: Journal of Insect Science
Ruilong Li, Huadong Tan, Yaxian Zhu, Yong Zhang
The polycyclic aromatic hydrocarbons (PAHs) located on the epidermal tissues showed distinctive toxic effects to root, while the retention and distribution of PAHs on mangrove seedlings poorly understood. Our results confirmed that the partition coefficients (Kf) of the PAHs retained on the epidermal tissue of mangrove roots, such as Kandelia obovata, Avicennia marina and Aegiceras corniculatum, were much higher than the Poaceae plants roots, for example wheat and maize (Wild et al., 2005). Moreover, to the parent and alkyl PAHs, a well negative correlation was observed between the surface polarity of these three species of mangrove root and the Kf values (p < 0...
April 15, 2017: Environmental Pollution
Clément Trellu, Nihal Oturan, Yoan Pechaud, Eric D van Hullebusch, Giovanni Esposito, Mehmet A Oturan
Formation of micelles at high surfactant concentration strongly modifies organic pollutant oxidation mechanisms and kinetics during anodic oxidation (AO) using boron doped diamond (BDD) anode. Results presented and discussed in this study emphasized the following mechanisms: (i) micelles act as a protective environment and reduce the availability of target molecules towards BDD((•)OH); (ii) the use of low current density strongly reduces micelle degradation kinetics due to both steric hindrance phenomenon for oxidation of micelles at the BDD surface and decrease of mediated oxidation in the bulk; (iii) compounds solubilized in surfactant-containing solutions can be either oxidized after degradation of the protective environment formed by micelles or if they are present as free extra-micellar compounds...
April 6, 2017: Water Research
Kai Bittermann, Simon Spycher, Kai-Uwe Goss
No abstract text is available yet for this article.
July 2017: Chemosphere
Marzieh Saeedi, Alexander P Lyubartsev, Seifollah Jalili
To provide insight into the molecular mechanisms of local anesthetic action, we have carried out an extensive investigation of two amide type local anesthetics, lidocaine and articaine in both charged and uncharged forms, interacting with DMPC lipid membrane. We have applied both standard molecular dynamics simulations and metadynamics simulations to provide a detailed description of the free energy landscape of anesthetics embedded in the lipid bilayer. The global minimum of the free energy surface (equilibrium position of anesthetics in the lipid membrane) occurred around 1nm of the bilayer center...
March 29, 2017: Biophysical Chemistry
Babak Basiri, Mandi M Murph, Michael G Bartlett
Alkylamines are widely used as ion-pairing agents during LC-MS of oligonucleotides. In addition to a better chromatographic separation, they also assist with the desorption of oligonucleotide ions into the gas phase, cause charge state reduction, and decrease cation adduction. However, the choice of such ion-pairing agents has considerable influence on the MS signal intensity of oligonucleotides as they can also cause significant ion suppression. Interestingly, optimal ion-pairing agents should be selected on a case by case basis as their choice is strongly influenced by the sequence of the oligonucleotide under investigation...
April 12, 2017: Journal of the American Society for Mass Spectrometry
Cassandra Rauert, Ajitha Kananathalingam, Tom Harner
This study highlights the potential of uptake into tree inner wood via direct-transfer through bark, as one contributing mechanism to describe atmospheric uptake of polycyclic aromatic compounds (PACs) into trees. The uptake of PACs into blue spruce tree wood was measured, with wood-air partition coefficients (KWOOD_AIR) determined for 5 PACs. A correlation between the octanol-air partition coefficient (KOA) and KWOOD_AIR for these 5 chemicals was determined and the KWOOD_AIR for 43 PACs were derived. A ratio of solubility (activity) difference between tree wood and octanol was also determined for these chemicals from this correlation...
April 12, 2017: Environmental Science & Technology
Giacomo Russo, Lucia Grumetto, Roman Szucs, Francesco Barbato, Frederic Lynen
In the present work, 79 structurally unrelated analytes were taken into account and their chromatographic retention coefficients, measured by Immobilized Artificial Membrane Liquid Chromatography (IAM-LC), and by Micellar Liquid Chromatography (MLC) employing sodium dodecyl sulfate (SDS) as surfactant, were determined. Such indexes were subsequently used for the development of Blood-Brain Barrier passage-predictive statistical models using partial least square (PLS) regression along with topological and physico-chemical parameters, calculated in silico...
April 11, 2017: Journal of Medicinal Chemistry
Javier Echeverría, Julia Opazo, Leonora Mendoza, Alejandro Urzúa, Marcela Wilkens
In this study, we tested eight naturally-occurring flavonoids-three flavanones and five flavones-for their possible antibacterial properties against four Gram-positive and four Gram-negative bacteria. Flavonoids are known for their antimicrobial properties, and due their structural diversity; these plant-derived compounds are a good model to study potential novel antibacterial mechanisms. The lipophilicity and the interaction of antibacterial compounds with the cell membrane define the success or failure to access its target...
April 10, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Zhenfu Zhang, Dan Yomo, Claudiu Gradinaru
Nonspecific interactions between lipids and fluorophores can alter the outcomes of single-molecule spectroscopy of membrane proteins in live cells, liposomes or lipid nanodiscs and of cytosolic proteins encapsulated in liposomes or tethered to supported lipid bilayers. To gain insight into these effects, we examined interactions between 9 dyes that are commonly used as labels for single-molecule fluorescence (SMF) and 6 standard lipids including cationic, zwitterionic and anionic types. The diffusion coefficients of dyes in the absence and presence of set amounts of lipid vesicles were measured by fluorescence correlation spectroscopy (FCS)...
April 6, 2017: Biochimica et Biophysica Acta
N Pi, J Z Ng, B C Kelly
Studies investigating the bioaccumulation behavior of perfluoroalkyl substances (PFASs) in aquatic macrophytes are limited. The present study involved controlled mesocosm experiments to assess uptake and elimination rate constants (ku,ke), bioconcentration factors (BCFs) and translocation factors (TFs) of several perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulfonic acids (PFSAs) in two aquatic plant species, including one submerged species (Echinodorus horemanii) and one free-floating species (Eichhornia crassipes)...
April 4, 2017: Water Research
E H Cabezas-Garcia, S J Krizsan, K J Shingfield, P Huhtanen
A meta-analysis based on an individual-cow data set was conducted to investigate the effects of between-cow variation and related animal variables on predicted CH4 emissions from dairy cows. Data were taken from 40 change-over studies consisting of a total of 637 cow/period observations. Animal production and rumen fermentation characteristics were measured for 154 diets in 40 studies; diet digestibility was measured for 135 diets in 34 studies, and ruminal digestion kinetics was measured for 56 diets in 15 studies...
April 5, 2017: Journal of Dairy Science
Michael von Domaros, Eva Perlt
The well-established quantum cluster equilibrium (QCE) model provides a statistical thermodynamic framework to apply high-level ab initio calculations of finite cluster structures to macroscopic liquid phases using the partition function. So far, the harmonic approximation has been applied throughout the calculations. In this article, we apply an important correction in the evaluation of the one-particle partition function and account for anharmonicity. Therefore, we implemented an analytical approximation to the Morse partition function and the derivatives of its logarithm with respect to temperature, which are required for the evaluation of thermodynamic quantities...
March 28, 2017: Journal of Chemical Physics
Julia Riede, Gian Camenisch, Jörg Huwyler, Birk Poller
Unbound intrahepatic drug concentrations determine the interaction potential with intracellular targets related to toxicity, pharmacokinetics or pharmacodynamics. Recently, the unbound liver-to-blood partition coefficient (Kpuu) based on the Extended Clearance Model (ECM) has been developed providing indirect estimates of unbound intrahepatic drug concentrations. This study aimed to determine Kpuu for 18 diverse drug compounds by three alternative in vitro methods and to compare the outcome with the ECM approach...
April 3, 2017: Journal of Pharmaceutical Sciences
Vesta Kohlmeier, George C Dragan, Erwin W Karg, Jürgen Schnelle-Kreis, Dietmar Breuer, Patricia B C Forbes, Egmont R Rohwer, Ralf Zimmermann
During many measurements it is important to account for possible changes in the gas-particle distribution of aerosols containing semi-volatile organic compounds (SVOCs). If denuders are combined with currently used personal air samplers, a simultaneous differential sampling of the gas and particle phase is possible. Here we analysed the transmission efficiency of denuders based on multi-channel silicone rubber traps (setup: 9 cm long glass liner (ID 4 mm), containing 22 parallel silicone rubber tubes (55 mm long, ID 0...
April 5, 2017: Environmental Science. Processes & Impacts
Hiroshi Kouno, Yosuke Iwai, Yoshiaki Uchida, Yuichiro Hirota, Norikazu Nishiyama
The evaluation of the transport rates of hydrophilic substances is important in agricultural and pharmaceutical chemistry and in the cosmetics and food-processing industries. Although there are some estimation methods focusing on the diffusion of the substances through the oil phase of the W/O/W core-shell double emulsions (oil microcapsules), all of them take several hours or days. This long-time measurement has a risk of rupture of the oil microcapsules, which causes significant errors. If it were possible to measure the transport rate of substances in the oil phase of the oil microcapsules in real time, the risk of rupture could be reduced...
April 4, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Jing Wang, Mei-Juan Zou, Lei Chen, Yi-Ling Sheng, Xiao-Mian Zhou, Xiang-Rong Zhang
The objective of this work is to synthesize indolacin-5-fluorouracil-1-ylmethyl ester and the structure was confirmed by means of UV, IR, (1)H-NMR, (13)C-NMR and mass spectrometry. The physicochemical parameters of melting point, solubility, apparent partition coefficient were investigated. S180 sarcoma, H22 hapatitic cancer and Lewis-transplanted mice were used to evaluate the anti-tumor activity of indolacini-5-fluorouracil-1-ylmethyl ester compared with 5-fluorouracil in vivo. Anti-inflammatory and analgesic activities were evaluated in mice...
November 2016: Pakistan Journal of Pharmaceutical Sciences
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