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partition coefficient

Simeon J A Visscher, Henk F van Stel
Child maltreatment (CM) is a common condition with a large impact on the victim and society. In the Netherlands, the preventive child healthcare (CHC) aims to protect children against such threats. However, several studies indicate that the efficacy in this area may be suboptimal for many CHC professionals. Therefore, this study aims to map the practice variation in the primary and secondary prevention of CM, by CHC physicians and nurses. This mixed-methods study used interviews to identify relevant topics and develop an online questionnaire...
June 19, 2017: Child Abuse & Neglect
Yang Yang, Meie Wang, Weiping Chen, Yanling Li, Chi Peng
Solid-solution partitioning coefficient (Kd) and plant uptake factor (PUF) largely determine the solubility and mobility of soil Cd to food crops. A four-year regional investigation was conducted in contaminated vegetable and paddy fields of southern China to quantify the variability in Kd and PUF. The distributions of Kd and PUF characterizing transfers of Cd from soil to vegetable and rice are probabilistic in nature. Dynamics in soil pH and soil Zn greatly affected the variations of Kd. In addition to soil pH, soil organic matter had a major influence on PUF variations in vegetables...
June 21, 2017: Journal of Agricultural and Food Chemistry
V K Sharma, Douglas G Hayes, Volker S Urban, Hugh M O'Neill, M Tyagi, E Mamontov
Bicontinous microemulsions (BμE) generally consist of nanodomains formed by surfactant in a mixture of water and oil at nearly equal proportions and are potential candidates for the solubilization and purification of membrane proteins. Here we present the first time report of nanoscopic dynamics of surfactant monolayers within BμEs formed by the anionic surfactant sodium dodecyl sulfate (SDS) measured on the nanosecond to picosecond time scale using quasielastic neutron scattering (QENS). BμEs investigated herein consisted of middle phases isolated from Winsor-III microemulsion systems that were formed by mixing aqueous and oil solutions under optimal conditions...
June 20, 2017: Soft Matter
T Almahayni, E Bailey, N M J Crout, G Shaw
In this study, the effects of incubation time and the method of soil solution extraction and filtration on the empirical distribution coefficient (Kd) obtained by de-sorbing indigenous selenium (Se) and iodine (I) from arable and woodland soils under temperate conditions were investigated. Incubation time had a significant soil- and element-dependent effect on the Kd values, which tended to decrease with the incubation time. Generally, a four-week period was sufficient for the desorption Kd value to stabilise...
June 16, 2017: Journal of Environmental Radioactivity
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
Hideo Kawamura, Yuuto Takeda, Takuro Tagawa, Hajime Katuura, Masaki Shiomi
The partition coefficients, Kx, of 1,2-alkanediols and α,ω-alkanediols between dodecyltrimethylammonium bromide (DTAB) micelles and water, and the change of the degree of counterion dissociation, dα/dXa(m), on DTAB micelles associated with solubilization of the alkanediols are determined by a differential conductivity technique. The standard Gibbs energy change of transfer per methylene group, ΔG(0)(CH2), is estimated from a dependence of logarithmic value of the Kx on the carbon number of alkyl chain in the alkanediols...
June 13, 2017: Journal of Oleo Science
Gabriela Bueno Franco Salla, Lívia Bracht, Anacharis Babeto de Sá-Nakanishi, Angela Valderrama Parizotto, Fabrício Bracht, Rosane Marina Peralta, Adelar Bracht
Dinoseb is a highly toxic pesticide of the dinitrophenol group. Its use has been restricted, but it can still be found in soils and waters in addition to being a component of related pesticides that, after ingestion by humans or animals, can originate the compound by enzymatic hydrolysis. As most dinitrophenols, dinoseb uncouples oxidative phosphorylation. In this study, distribution, lipid bilayer affinity and kinetics of the metabolic effects of dinoseb were investigated, using mainly the isolated perfused rat liver, but also isolated mitochondria and molecular dynamics simulations...
June 15, 2017: Toxicology and Applied Pharmacology
Kieran L Quinn, Erin M Macdonald, Muhammad M Mamdani, Christina Diong, David N Juurlink
BACKGROUND: Statins are commonly prescribed for the secondary prevention of ischemic stroke, but there is conflicting evidence as to whether they increase the risk of intracranial hemorrhage. Lipophilic statins cross the blood-brain barrier more freely than hydrophilic statins and may therefore increase the risk of intracranial hemorrhage. OBJECTIVE: To determine whether, in older patients following ischemic stroke, receipt of lipophilic statins was associated with differences in the risk of intracranial hemorrhage...
June 15, 2017: Drug Safety: An International Journal of Medical Toxicology and Drug Experience
Johann Bartel, R K Bhaduri, Matthias Brack, M V N Murthy
In this paper, we discuss P(n), the number of ways a given integer n may be written as a sum of primes. In particular, an asymptotic form P_{as}(n) valid for n→∞ is obtained analytically using standard techniques of quantum statistical mechanics. First, the bosonic partition function of primes, or the generating function of unrestricted prime partitions in number theory, is constructed. Next, the density of states is obtained using the saddle-point method for Laplace inversion of the partition function in the limit of large n...
May 2017: Physical Review. E
Feng Ding, Xianhai Yang, Guosong Chen, Jining Liu, Lili Shi, Jingwen Chen
The partition coefficients between bovine serum albumin (BSA) and water (KBSA/w) for ionogenic organic chemicals (IOCs) were different greatly from those of neutral organic chemicals (NOCs). For NOCs, several excellent models were developed to predict their logKBSA/w. However, it was found that the conventional descriptors are inappropriate for modeling logKBSA/w of IOCs. Thus, alternative approaches are urgently needed to develop predictive models for KBSA/w of IOCs. In this study, molecular descriptors that can be used to characterize the ionization effects (e...
June 10, 2017: Ecotoxicology and Environmental Safety
Vassilios S Vassiliou, Katharina Wassilew, Donnie Cameron, Ee Ling Heng, Evangelia Nyktari, George Asimakopoulos, Anthony de Souza, Shivraman Giri, Iain Pierce, Andrew Jabbour, David Firmin, Michael Frenneaux, Peter Gatehouse, Dudley J Pennell, Sanjay K Prasad
OBJECTIVES: Our objectives involved identifying whether repeated averaging in basal and mid left ventricular myocardial levels improves precision and correlation with collagen volume fraction for 11 heartbeat MOLLI T 1 mapping versus assessment at a single ventricular level. MATERIALS AND METHODS: For assessment of T 1 mapping precision, a cohort of 15 healthy volunteers underwent two CMR scans on separate days using an 11 heartbeat MOLLI with a 5(3)3 beat scheme to measure native T 1 and a 4(1)3(1)2 beat post-contrast scheme to measure post-contrast T 1, allowing calculation of partition coefficient and ECV...
June 12, 2017: Magma
Satoshi Endo, Yoshinori Yabuki, Shuhei Tanaka
Two sediment passive samplers, polyethylene (PE) and polyoxymethylene (POM), were compared and mutually validated for measuring freely dissolved concentrations (Cfree) of polychlorinated biphenyls (PCBs) in sediment porewater. PE and POM strips in commonly used dimensions (30 and 76 μm in thickness, respectively) were exposed to sediment slurries for 28 d. The Cfree values calculated using literature polymer-water partition coefficients were consistently higher for PE than for POM by a factor of 2 on average...
June 3, 2017: Chemosphere
Francis C P Law, Meicun Yao, Hui-Chang Bi, Stephen Lam
Although green tea (Camellia sinensis) (GT) contains a large number of polyphenolic compounds with anti-oxidative and anti-proliferative activities, little is known of the pharmacokinetics and tissue dose of tea catechins (TCs) as a chemical mixture in humans. The objectives of this study were to develop and validate a physiologically based pharmacokinetic (PBPK) model of tea catechin mixture (TCM) in rats and humans, and to predict an integrated or total concentration of TCM in the plasma of humans after consuming GT or Polyphenon E (PE)...
June 2017: Pharmacology Research & Perspectives
Ana M Barbero, H Frederick Frasch
The impact of the complex structure of the stratum corneum on transdermal penetration is not yet fully described by existing models. A quantitative and thorough study of skin permeation is essential for chemical exposure assessment and transdermal delivery of drugs. The objective of this study is to analyze the effects of heterogeneity, anisotropy, asymmetry, follicular diffusion, and location of the main barrier of diffusion on percutaneous permeation. In the current study, the solution of the transient diffusion through a two-dimensional-anisotropic brick-and-mortar geometry of the stratum corneum is obtained using the commercial finite element program COMSOL Multiphysics...
June 5, 2017: Journal of Controlled Release: Official Journal of the Controlled Release Society
Aniela Burant, Gregory V Lowry, Athanasios K Karamalidis
Carbon capture, utilization, and storage (CCUS), a climate change mitigation strategy, along with unconventional oil and gas extraction, generates enormous volumes of produced water containing high salt concentrations and a litany of organic compounds. Understanding the aqueous solubility of organic compounds related to these operations is important for water treatment and reuse alternatives, as well as risk assessment purposes. The well-established Setschenow equation can be used to determine the effect of salts on aqueous solubility...
June 6, 2017: Accounts of Chemical Research
Megan E Sawyer, Hien T Tran, Marina V Evans
Despite the plethora of studies discussing the benefits of vitamin D on physiological functioning, few mathematical models of vitamin D predict the response of the body on low-concentration supplementation of vitamin D under sunlight-restricted conditions. This study developed a physiologically based pharmacokinetic (PBPK) model utilizing published human data on the metabolic cascade of orally derived, low-concentration (placebo, 5 μg and 10 μg) supplementation of vitamin D over the course of 28 days in the absence of sunlight...
June 6, 2017: Journal of Applied Toxicology: JAT
Rainer Brandsch
Migration modelling provides reliable migration estimates from food contact materials (FCM) to food or food simulants based on mass transfer parameters like diffusion- and partition coefficients related to individual materials. In most cases mass transfer parameters are not readily available from the literature and for this reason are estimated with a given uncertainty. Historically uncertainty was accounted for by introducing upper limit concepts first, turning out to be of limited applicability due to highly overestimated migration results...
June 6, 2017: Food Additives & Contaminants. Part A, Chemistry, Analysis, Control, Exposure & Risk Assessment
Xin Xiao, Bridget A Ulrich, Baoliang Chen, Christopher P Higgins
Despite growing concerns about human exposure to perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS), other poly- and perfluoroalkyl substances (PFASs) derived from aqueous film-forming foams (AFFFs) have garnered little attention. While these other PFASs may also be present in AFFF-impacted drinking water, their removal by conventional drinking-water treatment is poorly understood. This study compared the removal of 30 PFASs, including 13 recently discovered PFASs, from an AFFF-impacted drinking water using carbonaceous sorbents (i...
June 6, 2017: Environmental Science & Technology
Daniel Molins-Delgado, João Távora, M Silvia Díaz-Cruz, Damià Barceló
The increased use of beauty and other daily use products, in particular those containing UV filters (UV-Fs) and benzotriazoles, results in their introduction in significant amounts into the aquatic environment. In this study, we aim to assess the occurrence and impact of UV-Fs and benzotriazoles in aquatic ecosystems in the metropolitan area of Barcelona, Spain. River water samples from the Llobregat and Besòs Rivers were analysed together with sediment, suspended particulate matter, and wastewater samples from 6 wastewater treatment plants (WWTPs) along their basins...
June 2, 2017: Science of the Total Environment
Rodrigo H D Nowaki, Serge-Étienne Parent, Arthur B Cecílio Filho, Danilo E Rozane, Natália B Meneses, Juliana A Dos Santos da Silva, William Natale, Léon E Parent
Over the past 20 years, the use of center-pivot irrigation has increased tomato (Solanum lycopersicum L.) yields in Brazil from 42 Mg ha(-1) to more than 80 Mg ha(-1). In the absence of field trials to support fertilizer recommendations, substantial amounts of phosphorus (P) have been applied to crops. Additional P dosing has been based on an equilibrated nutrient P budget adjusted for low-P fertilizer-use efficiency in high-P fixing tropical soils. To document nutrient requirements and prevent over-fertilization, tissue samples and crop yield data can be acquired through crop surveys and fertilizer trials...
2017: Frontiers in Plant Science
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