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Sampada Chitale, Joshua S Derasp, Bashir Hussain, Kashif Tanveer, André M Beauchemin
Directed hydration of α-amino nitriles was achieved under mild conditions using simple carbohydrates as catalysts exploiting temporary intramolecularity. A broadly applicable procedure using both formaldehyde and NaOH as catalysts efficiently hydrated a variety of primary and secondary susbtrates, and allowed the hydration of enantiopure substrates to proceed without racemization. This work also provides a rare comparison of the catalytic activity of carbohydrates, and shows that the simple aldehydes at the basis of chemical evolution are efficient organocatalysts mimicking the function of hydratase enzymes...
October 20, 2016: Chemical Communications: Chem Comm
Xiaoyang Shi, Hang Xiao, Klaus Lackner, Xi Chen
A great deal of information exists concerning the hydration of ions in bulk water. Much less noticeable, but equally ubiquitous is the hydration of ions holding on to several water molecules in nanoscopic pores or in natural air at low relative humidity. Such hydration of ions with a high ratio of ions to water molecules (up to 1:1) are essential in determining the energetics of many physical and chemical systems. Here we present a quantitative analysis of the energetics of ion hydration in nanopores based on molecular modeling of a series of basic salts associated with different numbers of water molecules...
October 20, 2016: Chemistry: a European Journal
Mordjane Boukhet, Fabien Piguet, Hadjer Ouldali, Manuela Pastoriza-Gallego, Juan Pelta, Abdelghani Oukhaled
The transport of macromolecules through nanopores is involved in many biological functions and is today at the basis of promising technological applications. Nevertheless the interpretation of the dynamics of the macromolecule/nanopore interaction is still misunderstood and under debate. At the nanoscale, inside biomimetic channels under an external applied voltage, electrophoresis, which is the electric force acting on electrically charged molecules, and electroosmotic flow (EOF), which is the fluid transport associated with ions, contribute to the direction and magnitude of the molecular transport...
October 20, 2016: Nanoscale
Ming Yan, Guangming Zeng, Xiaoming Li, Jianmin He, Guiqiu Chen, Danlian Huang, Lin Tang, Cui Lai, Chang Zhang, Xiaodong Li, Lichao Wang, Zhi Guo, Wei Tao
Solidification is a very effective way to alleviate heavy metal impacts to the environment. In this paper, an improved method was adopted herein for the solidification/stabilization (S/S) of sediments with cement-based additives and low content of cement in S/S materials. Sediments in Xiangjiang River, containing high concentrations of Cu, Cd, and Pb, were solidified/stabilized by binders of cement, fly ash, and bentonite. Admixtures such as sodium lignosulfonate, sodium lauryl sulfate, and triethanolamine were used to improve the bonding properties of S/S, which had never been investigated before...
October 19, 2016: Environmental Science and Pollution Research International
Laureano M Alarcón, M de Los Angeles Frías, Marcela A Morini, M Belén Sierra, Gustavo A Appignanesi, E Anibal Disalvo
We employ molecular dynamics simulations to study the hydration properties of Dipalmitoylphosphatidylcholine (DPPC) bilayers, both in the gel and the liquid crystalline states. We show that while the tight hydration centers (PO and CO moieties) are significantly hydrated in both phases, the gel-fluid transition involves significant changes at the second hydration shell, particularly at the buried region between the hydrocarbon tails. Thus, while almost no buried water population exists in the gel state below the carbonyls, this hydrophobic region becomes partially water accesible in the liquid crystalline state...
October 2016: European Physical Journal. E, Soft Matter
Nir Kampf, Chunxian Wu, Yilin Wang, Jacob Klein
The surface structure of the trimeric surfactant tri(dodecyldimethylammonioacetoxy)-diethyltriamine trichloride (DTAD) on mica, and the interactions between two such DTAD-coated surfaces were determined using atomic force microscopy and a surface force balance. In an aqueous solution of 3 mM, five times the critical aggregation concentration (CAC), the surfaces are coated with worm-like micelles or hemi-micelles and larger (ca. 80 nm) bilayer vesicles. Repulsive normal interactions between the surfaces indicate a net surface charge and a solution concentration of ions close to that expected from the CAC...
October 19, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Masayuki Kyomoto, Toru Moro, Shihori Yamane, Yoshio Takatori, Sakae Tanaka, Kazuhiko Ishihara
The surface and substrate of a cross-linked polyethylene (CLPE) liner are designed to achieve resistance against oxidative degradation in the construction of hip joint replacements. In this study, we aimed to evaluate the oxidative degradation caused by lipid absorption of a highly hydrophilic nanometer-scaled thickness layer prepared by grafting a poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) layer and a high-dose gamma-ray irradiated CLPE with vitamin E blending (HD-CLPE[VE]). The HD-CLPE(VE) and PMPC-grafted HD-CLPE(VE) exhibited extremely high oxidation resistance regardless of lipid absorption, even though residual-free radical levels were detectable...
October 11, 2016: Biomaterials
Matthew D Parker, Lynette A Jones, Ian W Hunter, A J Taberner, M P Nash, P M F Nielsen
A triaxial force-sensitive microrobot was developed to dynamically perturb skin in multiple deformation modes, in vivo. Wiener static nonlinear identification was used to extract the linear dynamics and static nonlinearity of the force-displacement behavior of skin. Stochastic input forces were applied to the volar forearm and thenar eminence of the hand, producing probe tip perturbations in indentation and extension. Wiener static nonlinear approaches increased the variance accounted for by 0.1 % to 3.4 % over linear approaches, to 94 % to 97 %...
October 19, 2016: Journal of Biomechanical Engineering
(no author information available yet)
This corrects the article DOI: 10.20960/nh.308.
October 11, 2016: Nutrición Hospitalaria: Organo Oficial de la Sociedad Española de Nutrición Parenteral y Enteral
Efsun Kaabudak, Eda Koksal
OBJECTIVE: The purpose of this investigation is to test the validity and reliability the assessment methods for the true beverage consumption of adults. METHODS: This cross-sectional study was carried out 291 healthy volunteers. The beverage intake questionnaire (BIQ) was prepared in combination with a new one which is developed based on basic principles and the existing one developed for the beverages consumed the most with respect to frequency and amount by Turkish populations...
September 20, 2016: Nutrición Hospitalaria: Organo Oficial de la Sociedad Española de Nutrición Parenteral y Enteral
Stephan Ingmar Brückner, Sergii Donets, Arezoo Dianat, Manfred Bobeth, Rafael Gutierrez, Gianaurelio Cuniberti, Eike Brunner
Understanding the molecular interactions between inorganic phases such as silica and organic material is fundamental for chromatographic applications, for tailoring silica-enzyme interactions, and for elucidating the mechanisms of biomineralization. The formation, structure, and properties of the organic/inorganic interface is crucial in this context. Here, we investigate the interaction of selectively (13)C-labeled choline with (29)Si-labeled monosilicic acid/silica at the molecular level. Silica/choline nanocomposites were analyzed by solid-state NMR spectroscopy in combination with extended molecular dynamics (MD) simulations to understand the silica/organic interface...
October 19, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Aaron J Celestian, Caleb J Chappell, Melinda J Rucks, Pauline Norris
The ion exchange of yttrium, one of the five most critical rare-earth elements as outlined by the U.S. Department of Energy, into ETS-4 is a dynamic, multistep ion exchange process. The ion exchange process was followed using in situ time-resolved Raman spectroscopy, and the crystal structures of the pre-exchange and post-exchange forms were determined by single-crystal X-ray diffraction. In situ Raman spectroscopy is an ideal tool for this type of study, as it measures the spectral changes that are a result of molecular geometry changes at fast time intervals, even where symmetry and unit volume changes are minimally detected by X-ray diffraction...
October 19, 2016: Inorganic Chemistry
Justin A Lemkul, Alexander D MacKerell
Mg2+ ions are important in biological systems, particularly in stabilizing compact RNA folds. Mg2+ is strongly polarizing, and representing its interactions in heterogeneous environments is a challenge for empirical force field development. To date, the most commonly used force fields in molecular dynamics simulations utilize a pairwise-additive approximation for electrostatic interactions, which cannot account for the significant polarization response in systems containing Mg2+. In the present work, we refine the interactions of Mg2+ with water, Cl- ions, and nucleic acid moieties using a polarizable force field based on the classical Drude oscillator model...
October 19, 2016: Journal of Physical Chemistry. B
Florentina Sophie Ferstl, Alice Miriam Kitay, Rebecca Marion Trattnig, Abrar Alsaihati, John Peter Geibel
Prolonged exposure to gastric acid is a leading cause of gastroesophageal reflux disease (GERD) and esophagitis. With the ever increasing number of patients showing insensitivity to proton-pump-inhibitor (PPI) therapy with recurrence of symptoms over time, alternative treatment options remain an important issue. Previous studies from our laboratory have shown that a zinc sulfate salt can inhibit HCl generation at the cellular level of the parietal cell. In this paper, we examine the difference between two hydration forms of ZnSO4 (monohydrate H2O and heptahydrate 7H2O) in their entry characteristics into the parietal cell under several physiological conditions associated with acid secretion...
October 19, 2016: Pflügers Archiv: European Journal of Physiology
Baki Vijaya Bhaskar, Tirumalasetty Muni Chandra Babu, Netala Vasudeva Reddy, Wudayagiri Rajendra
Emerging drug resistance in clinical isolates of Staphylococcus aureus might be implicated to the overexpression of NorA efflux pump which is capable of extruding numerous structurally diverse compounds. However, NorA efflux pump is considered as a potential drug target for the development of efflux pump inhibitors. In the present study, NorA model was constructed based on the crystal structure of glycerol-3-phosphate transporter (PDBID: 1PW4). Molecular dynamics (MD) simulation was performed using NAMD2.7 for NorA which is embedded in the hydrated lipid bilayer...
2016: Drug Design, Development and Therapy
Tijen Kaya Temiz, Omer Demir, Fatma Simsek, Yusuf Cem Kaplan, Selen Bahceci, Barıs Karadas, Aslı Celik, Gokhan Koyluoglu
AIM: The aim of this study is to investigate whether nitric oxide (NO)-mediated colonic motility was altered in rat irritable bowel syndrome (IBS) model, using different isoforms of NO-synthase (NOS) inhibitors. MATERIALS AND METHODS: The animal model of IBS-like visceral hypersensitivity was induced by intra-colonic infusion of 0.5% acetic acid (AA) in saline once daily from postnatal days 8 to 21. Control animals received saline instead of AA. Experiments were performed at the end of 8 weeks...
July 2016: Indian Journal of Pharmacology
Mai Ohba, Tomoichiro Oka, Takayuki Ando, Saori Arahata, Asaka Ikegaya, Hirotaka Takagi, Naohisa Ogo, Chelsea Zhu, Kazuhiro Owada, Fumihiko Kawamori, Qiuhong Wang, Linda J Saif, Akira Asai
Caliciviruses are contagious pathogens of humans and various animals. They are the most common cause of viral gastroenteritis in humans, and can cause lethal diseases in domestic animals such as cats, rabbits and immunocompromised mice. In this study, we conducted cytopathic effect-based screening of 2080 selected compounds from our in-house library to find antiviral compounds against three culturable caliciviruses: feline calicivirus, murine norovirus (MNV) and porcine sapovirus (PoSaV). We identified active six compounds, of which two compounds, both related to theaflavins, showed broad antiviral activities against all three caliciviruses; three compounds (abamectin, a mixture of avermectin B1a and B1b; avermectin B1a; and (-)-epigallocatechin gallate hydrate) were effective against PoSaV only; and a heterocyclic carboxamide derivative (BFTC) specifically inhibited MNV infectivity in cell cultures...
October 19, 2016: Journal of Antibiotics
Yang Ruan, Yudan Zhu, Yumeng Zhang, Qingwei Gao, Xiaohua Lu, Linghong Lu
Residual Mg2+ could reduce the performance of lithium-ion batteries, but separating Mg2+ and Li+ is difficult because of their similar ionic properties. Inspired by the high selectivity of biological Mg2+ channels, this work investigates the ability of graphene-based nanopores with different diameters (0.789, 1.024 and 1.501 nm) to separate Mg2+ and Li+ under a series of transmembrane voltages using atomistic simulations. We analyzed the spatial distribution of molecules in the pore vicinity, ionic hydration structure properties, and potential of mean force of ions traveling through the nanopores...
October 18, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Mark J DelloStritto, James David Kubicki, Jorge Osvaldo Sofo
We use ab-initio molecular dynamics simulations to study the effect of ions on the structure and dynamics of the quartz(101)-water interface. We study several IA (Na(+),Rb(+)) and IIA (Mg(2+),Sr(2+)) cations, with Cl(-) as counterion, adsorbed onto acidic, neutral, and basic surface configurations at 300K and 373K. We find that both cations and anions can bond directly to the surface and perturb the local H-bond network. The adsorbed ions promote the formation of intrasurface H-bonds, as shown by vibrational density of states and orientations of the surface silanols...
October 18, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Airek R Mathews, Shane S Que Hee
The differences in permeation parameters when a gloved dextrous robot hand clenched and did not were investigated with the dynamic permeation system described in the companion paper. Increased permeation through the gloves of the present study for cyclohexanol when the gloved hand clenched depended on glove thickness and porosity for cyclohexanol permeation. The Sterling glove, the thinnest and the most porous, was the least protective. Hand clenching promoted more permeation for the Sterling glove in terms of breakthrough times, steady state permeation rate, and diffusion coefficient...
October 18, 2016: Journal of Occupational and Environmental Hygiene
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