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Phase separation

Andleeb Z Naqvi, Kabir-Ud-Din
Phase separation in amphiphilic systems is an important phenomenon. The temperature at which an amphiphilic solution phase separates is known as Cloud Point (CP). This article reviews in detail the process of phase separation in various amphiphiles (surfactants, polymers and drugs) and effect of different classes of additives on the CP of these amphiphilic systems. Ions affect the CP of drugs in a different way: kosmotropes and hard bases decrease while chaotropes and soft bases increase the CP of nonionic and cationic surfactants...
February 3, 2018: Colloids and Surfaces. B, Biointerfaces
Tahereh Shojaeimehr, Farshad Rahimpour, Michael Schwarze, Jens-Uwe Repke, Hamid Reza Godini, Günter Wozny
The present study evaluates the capability of ion exclusion chromatography (IEC) of short chain aliphatic carboxylic acids using a cation exchange column (8% sulfonated cross-linked styrene-divinylbenzene copolymer) in different experimental conditions. Since one of the prerequisites to the development of an efficient carboxylic acid separation process is to obtain the optimum operational conditions, response surface methodology (RSM) was used to develop an approach to evaluate carboxylic acids separation process in IEC columns...
March 8, 2018: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
Shushan He, Lutz Maibaum
Understanding the (de)mixing behavior of multicomponent lipid bilayers is an important step towards unraveling the nature of spatial composition heterogeneities in cellular membranes and their role in biological function. We use coarse-grained molecular dynamics simulations to study the composition phase diagram of a quaternary mixture of phospholipids and cholesterol. This mixture is known to exhibit both uniform and coexisting phases. We compare and combine different statistical measures of membrane structure to identify the onset of phase coexistence in composition space...
March 16, 2018: Journal of Physical Chemistry. B
Waqas Hameed, Bilal Iqbal Avan
INTRODUCTION: Respectful and dignified healthcare is a fundamental right for every woman. However, many women seeking childbirth services, especially those in low-income countries such as Pakistan, are mistreated by their birth attendants. The aim of this epidemiological study was to estimate the prevalence of mistreatment and types of mistreatment among women giving birth in facility- and home-based settings in Pakistan in order to address the lack of empirical evidence on this topic...
2018: PloS One
Shannon N Rhoads, Zachary T Monahan, Debra S Yee, Frank P Shewmaker
Subcellular mislocalization and aggregation of the human FUS protein occurs in neurons of patients with subtypes of amyotrophic lateral sclerosis and frontotemporal dementia. FUS is one of several RNA-binding proteins that can functionally self-associate into distinct liquid-phase droplet structures. It is postulated that aberrant interactions within the dense phase-separated state can potentiate FUS's transition into solid prion-like aggregates that cause disease. FUS is post-translationally modified at numerous positions, which affect both its localization and aggregation propensity...
March 16, 2018: International Journal of Molecular Sciences
Jovan Nikolic, Cécile Lagaudrière-Gesbert, Nathalie Scrima, Danielle Blondel, Yves Gaudin
No abstract text is available yet for this article.
March 2018: Médecine Sciences: M/S
Naoki Ohno, Tosiaki Miyati, Shuto Suzuki, Hirohito Kan, Toshitaka Aoki, Yoshitaka Nakamura, Yuki Hiramatsu, Satoshi Kobayashi, Toshifumi Gabata
PURPOSE: To suppress olefinic signals and enable simultaneous and quantitative estimation of multiple functional parameters associated with water and lipid, we investigated a modified method using chemical shift displacement and recovery-based separation of lipid tissue (SPLIT) involving acquisitions with different inversion times (TIs), echo times (TEs), and b-values. MATERIALS AND METHODS: Single-shot diffusion echo-planar imaging (SSD-EPI) with multiple b-values (0-3000 s/mm2 ) was performed without fat suppression to separate water and lipid images using the chemical shift displacement of lipid signals in the phase-encoding direction...
March 12, 2018: Magnetic Resonance Imaging
K Louati, I Bargaoui, F Safta
The main objective was to develop a suitable and rapid ultra-performance liquid chromatography (UPLC) method for the quantitative determination of meloxicam and its impurities. Starting from data in literature, we calculated the new parameters to translate a high performance liquid chromatography method used for the analysis of meloxicam with its major degradation products to UPLC method, and then we switched on many trials to optimize and improve its analytical performance. Chromatographic separation was achieved on ACQUITY UPLC HSS-T3 (2...
March 12, 2018: Annales Pharmaceutiques Françaises
Veronika Sele, Robin Ørnsrud, Jens J Sloth, Marc H G Berntssen, Heidi Amlund
Selenium (Se) is an essential element for animals, including fish. Due to changes in feed composition for Atlantic salmon (Salmo salar), it may be necessary to supplement feeds with Se. In the present work, the transfer of Se and Se species from feed to muscle of Atlantic salmon fed Se supplemented diets was studied. Salmon were fed basal fish feed (0.35 mg Se/kg and 0.89 mg Se/kg feed), or feed supplemented either with selenised yeast or sodium selenite, at low (1-2 mg Se/kg feed) and high (15 mg Se/kg feed) levels, for 12 weeks...
May 2018: Journal of Trace Elements in Medicine and Biology
Matthew S Church, Timothy J H Hele, Gregory S Ezra, Nandini Ananth
We extend the Mixed Quantum-Classical Initial Value Representation (MQC-IVR), a semiclassical method for computing real-time correlation functions, to electronically nonadiabatic systems using the Meyer-Miller-Stock-Thoss (MMST) Hamiltonian in order to treat electronic and nuclear degrees of freedom (dofs) within a consistent dynamic framework. We introduce an efficient symplectic integration scheme, the MInt algorithm, for numerical time evolution of the phase space variables and monodromy matrix under the non-separable MMST Hamiltonian...
March 14, 2018: Journal of Chemical Physics
Sylvie Antoun, M Ziad Saghir, Seshasai Srinivasan
In multicomponent liquid mixtures, the diffusion flow of chemical species can be induced by temperature gradients, which leads to a separation of the constituent components. This cross effect between temperature and concentration is known as thermodiffusion or the Ludwig-Soret effect. The performance of boundary driven non-equilibrium molecular dynamics along with the enhanced heat exchange (eHEX) algorithm was studied by assessing the thermodiffusion process in n-pentane/n-decane (nC5 -nC10 ) binary mixtures...
March 14, 2018: Journal of Chemical Physics
Zelig Chernia, Yoav Tsori
Phase separation in substituted pyridines in water is usually described as an interplay between temperature-driven breakage of hydrogen bonds and the associating interaction of the van der Waals force. In previous quantum-chemical studies, the strength of hydrogen bonding between one water and one pyridine molecules (the 1:1 complex) was assigned a pivotal role. It was accepted that the disassembly of the 1:1 complex at a critical temperature leads to phase separation and formation of the miscibility gap. Yet, for over two decades, notable empirical data and theoretical arguments were presented against that view, thus revealing the need in a revised quantum-mechanical description...
March 14, 2018: Journal of Chemical Physics
Yilong Hua, Wei Wang, Xiaoyue Huang, Tianhang Gu, Dexin Ding, Lan Ling, Wei-Xian Zhang
Bicarbonate, ubiquitous in natural and waste waters is an important factor regulating the rate and efficiency of pollutant separation and transformation. For example, it can form complexes with U(VI) in the aqueous phase and at the solid-water interface. In this work, we investigated the effect of bicarbonate on the aging of nanoscale zero-valent (nZVI) in the context of U(VI) reduction and removal from wastewater. For fresh nZVI, over 99% aqueous uranium was separated in less than 10 min, of which 83% was reduced from U(VI) to U(IV)...
March 6, 2018: Chemosphere
Yan-Mei Lei, Bai-Qi Xiao, Wen-Bin Liang, Ya-Qin Chai, Ruo Yuan, Ying Zhuo
It is well known that the conventional electrochemiluminescence (ECL) biosensor rely on the heterogeneous assay formats that involves the immobilization of biorecognition probe on the electrode surface before signal collection, which inevitably cause the efficiency of bio-recognition reactions to be limited owing to the existence of local steric hindrance. Herein, a robust, magnetic, and self-accelerated ECL nanosensor based on the multifunctionalized cobalt ferrite magnetite nanoparticles (CoFe2 O4 MNPs) was firstly designed for copper ion (Cu2+ ) detection in quasi-homogeneous system...
March 7, 2018: Biosensors & Bioelectronics
Saisi Xue, A Daniel Jones, Leonardo Sousa, Jeff Piotrowski, Mingjie Jin, Cory Sarks, Bruce E Dale, Venkatesh Balan
Biochemical conversion of lignocellulosic biomass to liquid fuels requires pretreatment and enzymatic hydrolysis of the biomass to produce fermentable sugars. Degradation products produced during thermochemical pretreatment, however, inhibit the microbes with regard to both ethanol yield and cell growth. In this work, we used synthetic hydrolysates (SynH) to study the inhibition of yeast fermentation by water-soluble components (WSC) isolated from lignin streams obtained after extractive ammonia pretreatment (EA)...
2018: PloS One
Clarisse Ribeiro, Carlos M Costa, Daniela M Correia, João Nunes-Pereira, Juliana Oliveira, Pedro Martins, Renato Gonçalves, Vanessa F Cardoso, Senentxu Lanceros-Méndez
Poly(vinylidene fluoride) (PVDF) and its copolymers are the polymers with the highest dielectric constants and electroactive responses, including piezoelectric, pyroelectric and ferroelectric effects. This semicrystalline polymer can crystallize in five different forms, each related to a different chain conformation. Of these different phases, the β phase is the one with the highest dipolar moment and the highest piezoelectric response; therefore, it is the most interesting for a diverse range of applications...
April 2018: Nature Protocols
Sreetama Pal, Nirnay Samanta, Debasish Das Mahanta, Rajib Kumar Mitra, Amitabha Chattopadhyay
Biological membranes are highly organized supramolecular assemblies of lipids and proteins. The membrane interface separates the outer (bulk) aqueous phase from the hydrophobic membrane interior. In this work, we have explored the microstructure and collective dynamics of the membrane interfacial hydration shell in zwitterionic and negatively charged phospholipid membrane bilayers using terahertz time-domain spectroscopy. We show here that the relaxation time constants of water hydrogen bond network exhibit a unique "rise and dip" pattern with increasing lipid concentration...
March 15, 2018: Journal of Physical Chemistry. B
Hongbo Xie, Hucheng Pan, Yuping Ren, Liqing Wang, Yufeng He, Xixi Qi, Gaowu Qin
All of the AB_{2} Laves phases discovered so far satisfy the general crystalline structure characteristic of translational symmetry; however, we report here a new structured Laves phase directly precipitated in an aged Mg-In-Ca alloy by using aberration-corrected scanning transmission electron microscopy. The nanoprecipitate is determined to be a (Mg,In)_{2}Ca phase, which has a C14 Laves structure (hcp, space group: P6_{3}/mmc, a=6.25  Å, c=10.31  Å) but without any translational symmetry on the (0001)_{p} basal plane...
February 23, 2018: Physical Review Letters
Timothy J Proctor, Paul A Knott, Jacob A Dunningham
We introduce a general model for a network of quantum sensors, and we use this model to consider the following question: When can entanglement between the sensors, and/or global measurements, enhance the precision with which the network can measure a set of unknown parameters? We rigorously answer this question by presenting precise theorems proving that for a broad class of problems there is, at most, a very limited intrinsic advantage to using entangled states or global measurements. Moreover, for many estimation problems separable states and local measurements are optimal, and can achieve the ultimate quantum limit on the estimation uncertainty...
February 23, 2018: Physical Review Letters
Mark Hindmarsh
A model for the acoustic production of gravitational waves at a first-order phase transition is presented. The source of gravitational radiation is the sound waves generated by the explosive growth of bubbles of the stable phase. The model assumes that the sound waves are linear and that their power spectrum is determined by the characteristic form of the sound shell around the expanding bubble. The predicted power spectrum has two length scales, the average bubble separation and the sound shell width when the bubbles collide...
February 16, 2018: Physical Review Letters
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