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https://www.readbyqxmd.com/read/27936325/effect-of-heteroatom-substitution-on-transport-in-alkane-dithiol-based-molecular-tunnel-junctions-evidence-for-universal-behavior
#1
Zuoti Xie, Ioan Baldea, Stuart Oram, Christopher E Smith, C Daniel Frisbie
The transport properties of molecular junctions based on alkane dithiols with three different methylene chain lengths were compared with junctions based on similar chains wherein every third -CH2- was replaced with O or S, i.e., following the general formula: HS(CH2CH2X)nCH2CH2SH, where X = CH2, O or S, and n = 1, 2, or 3. Conducting probe atomic force microscopy (CP-AFM) revealed that the low bias resistance of the chains increased upon substitution in the order CH2 < O < S. This change in resistance is ascribed to the observed identical trend in contact resistance, R_c, whereas the exponential prefactor β (length sensitivity) was essentially the same for all chains...
December 9, 2016: ACS Nano
https://www.readbyqxmd.com/read/27935675/encapsulation-of-either-of-hydrophilic-or-hydrophobic-substances-in-spongy-cellulose-particles
#2
Taro Omura, Kaori Imagawa, Kyosuke Kono, Toyoko Suzuki, Hideto Minami
We have reported the cellulose particles with a spongy structure, which we prepared by the solvent releasing method (SRM) from cellulose droplets comprising cellulose, 1-butyl-3-methylimidazoliumchrolide ([Bmim]Cl), and N,N-dimethylformamide (DMF). The spongy structure collapsed as the medium evaporated, resulting in dense cellulose particles. In this study, we encapsulated the hydrophilic and hydrophobic fluorescent substances in these particles to investigate the use of such particles in potential applications that require encapsulating of substances (e...
December 9, 2016: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/27935089/the-mechanisms-of-nickel-toxicity-in-aquatic-environments-an-adverse-outcome-pathway-aop-analysis
#3
Kevin V Brix, Christian E Schlekat, Emily R Garman
Current ecological risk assessment and water quality regulation for nickel (Ni) use mechanistically-based, predictive tools such as Biotic Ligand Models (BLMs). However, despite many detailed studies, the precise mechanism(s) of Ni toxicity to aquatic organisms remains elusive. This uncertainty in the mechanism(s) of action for Ni has led to concern over the use of tools like the BLM in some regulatory settings. To begin addressing this knowledge gap, we used an Adverse Outcome Pathway (AOP) analysis, the first AOP for a metal, to identify multiple potential mechanisms of Ni toxicity and their interactions to freshwater aquatic organisms...
December 9, 2016: Environmental Toxicology and Chemistry
https://www.readbyqxmd.com/read/27934934/long-duration-of-ground-motion-in-the-paradigmatic-valley-of-mexico
#4
V M Cruz-Atienza, J Tago, J D Sanabria-Gómez, E Chaljub, V Etienne, J Virieux, L Quintanar
Built-up on top of ancient lake deposits, Mexico City experiences some of the largest seismic site effects worldwide. Besides the extreme amplification of seismic waves, duration of intense ground motion from large subduction earthquakes exceeds three minutes in the lake-bed zone of the basin, where hundreds of buildings collapsed or were seriously damaged during the magnitude 8.0 Michoacán earthquake in 1985. Different mechanisms contribute to the long lasting motions, such as the regional dispersion and multiple-scattering of the incoming wavefield from the coast, more than 300 km away the city...
December 9, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27934226/%C3%AE-galactosidase-langmuir-monolayer-at-air-x-gal-subphase-interface
#5
Shiv K Sharma, Shanghao Li, Miodrag Micic, Jhony Orbulescu, Daniel Weissbart, Hiromichi Nakahara, Osamu Shibata, Roger M Leblanc
This article investigates the surface chemistry properties of the β-galactosidase monolayer at the air-subphase interface at the vicinity of its substrate, X-gal. We have demonstrated that the β-galactosidase in the monolayer form remained active and performed hydrolysis of the X-gal in the subphase. We investigated the β-galactosidase Langmuir monolayer in absence and presence of X-gal in the subphase of varying concentration of X-gal with the sodium chloride solution. It was found that the limiting molecular area as well as the collapse surface pressure kept on decreasing with the increasing concentration of X-gal...
December 8, 2016: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/27934097/squeezing-of-ion-populations-and-peaks-in-traveling-wave-ion-mobility-separations-and-structures-for-lossless-ion-manipulations-using-compression-ratio-ion-mobility-programming
#6
Sandilya V B Garimella, Ahmed M Hamid, Liulin Deng, Yehia M Ibrahim, Ian K Webb, Erin S Baker, Spencer A Prost, Randolph V Norheim, Gordon A Anderson, Richard D Smith
In this work we report an approach for spatial and temporal gas-phase ion population manipulation, wherein we collapse ion distributions in ion mobility (IM) separations into tighter packets providing higher sensitivity measurements in conjunction with mass spectrometry (MS). We do this for ions moving from a conventional traveling wave (TW)-driven region to a region where the TW is intermittently halted or "stuttered". This approach causes the ion packets spanning a number of TW-created traveling traps (TT) to be redistributed into fewer TT, resulting in spatial compression...
December 6, 2016: Analytical Chemistry
https://www.readbyqxmd.com/read/27934025/pressure-driven-cooperative-spin-crossover-large-volume-collapse-and-semiconductor-to-metal-transition-in-manganese-ii-honeycomb-lattices
#7
Yonggang Wang, Zhengyang Zhou, Ting Wen, Yannan Zhou, Nana Li, Fei Han, Yuming Xiao, Paul Chow, Junliang Sun, Michael Pravica, Andrew L Cornelius, Wenge Yang, Yusheng Zhao
Spin-crossover (SCO) is generally regarded as a spectacular molecular magnetism in 3d(4)-3d(7) metal complexes and holds great promise for various applications such as memory, displays, and sensors. In particular, SCO materials can be multifunctional when a classical light- or temperature-induced SCO occurs along with other cooperative structural and/or electrical transport alterations. However, such a cooperative SCO has rarely been observed in condensed matter under hydrostatic pressure (an alternative external stimulus to light or temperature), probably due to the lack of synergy between metal neighbors under compression...
December 7, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/27933937/hydrophobic-polymer-chain-in-water-that-undergoes-a-coil-to-globule-transition-near-room-temperature
#8
I Hatano, K Mochizuki, T Sumi, K Koga
A simple model of a hydrophobic polymer in water is studied. The model polymer, a chain of Lennard-Jones particles with a fixed bond length, is designed in such a way that it undergoes a coil-to-globule conformational change near room temperature upon heating in liquid water. At low temperatures (≲270 K), the polymer chain under vacuum takes a globular conformation, whereas in water, it adopts an extended form. At higher temperatures (≳320 K), the polymer has a more compact conformation in water than under vacuum...
December 1, 2016: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/27933833/tunable-pickering-emulsions-with-environmentally-responsive-hairy-silica-nanoparticles
#9
Min Liu, Xiaoli Chen, Zongpeng Yang, Zhou Xu, Liangzhi Hong, To Ngai
Surface modification of the nanoparticles using surface anchoring of amphiphilic polymers offers considerable scope for the design of a wide range of brush-coated hybrid nanoparticles with tunable surface wettability that may serve as new class of efficient Pickering emulsifiers. In the present study, we prepared mixed polymer brush-coated nanoparticles by grafting ABC miktoarm star terpolymers consisting of poly(ethylene glycol), polystyrene, and poly[(3-triisopropyloxysilyl)propyl methacrylate] (μ-PEG-b-PS-b-PIPSMA) on the surface of silica nanoparticles...
November 30, 2016: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/27933452/responses-of-tropical-legumes-from-the-brazilian-atlantic-rainforest-to-simulated-acid-rain
#10
Guilherme C Andrade, Luzimar C Silva
We investigated the morphological and anatomical effects of simulated acid rain on leaves of two species native to the Brazilian Atlantic Rainforest: Paubrasilia echinata and Libidibia ferrea var. leiostachya. Saplings were subjected to acid rain in a simulation chamber during 10 days for 15 min daily, using H2SO4 solution pH 3.0 and, in the control, deionized water. At the end of the experiment, fragments from young and expanding leaves were anatomically analyzed. Although L. ferrea var. leiostachya leaves are more hydrophobic, rain droplets remained in contact with them for a longer time, as in the hydrophilic P...
December 8, 2016: Protoplasma
https://www.readbyqxmd.com/read/27933256/explaining-bioenergy-representations-of-jatropha-in-kenya-before-and-after-disappointing-results
#11
Carol Hunsberger
Proponents of Jatropha curcas portrayed the crop as a 'sustainable biofuel' that was less threatening to food security and forests than other energy crops, creating a reputation that helped jatropha projects to multiply quickly throughout the global South. However, many jatropha initiatives failed to thrive and ultimately collapsed. This paper investigates how actors involved with jatropha in Kenya explained their visions of bioenergy at two points in time. In 2009, when many activities were beginning, I interviewed small-scale farmers, NGO staff, researchers, donors, government officials and members of the private sector about their expectations of jatropha as an energy crop...
2016: SpringerPlus
https://www.readbyqxmd.com/read/27932572/a-mechanism-for-acetylcholine-receptor-gating-based-on-structure-coupling-phi-and-flip
#12
Shaweta Gupta, Srirupa Chakraborty, Ridhima Vij, Anthony Auerbach
Nicotinic acetylcholine receptors are allosteric proteins that generate membrane currents by isomerizing ("gating") between resting and active conformations under the influence of neurotransmitters. Here, to explore the mechanisms that link the transmitter-binding sites (TBSs) with the distant gate, we use mutant cycle analyses to measure coupling between residue pairs, phi value analyses to sequence domain rearrangements, and current simulations to reproduce a microsecond shut component ("flip") apparent in single-channel recordings...
December 8, 2016: Journal of General Physiology
https://www.readbyqxmd.com/read/27932282/serum-cardiac-troponin-i-in-canine-syncope-and-seizures
#13
E Dutton, J Dukes-McEwan, P J Cripps
OBJECTIVE: To determine if serum cardiac troponin I (cTnI) concentration distinguishes between cardiogenic syncope and collapsing dogs presenting with either generalized epileptic seizures (both with and without cardiac disease) or vasovagal syncope. ANIMALS: Seventy-nine prospectively recruited dogs, grouped according to aetiology of collapse: generalized epileptic seizures (group E), cardiogenic syncope (group C), dogs with both epileptic seizures and cardiac disease (group B), vasovagal syncope (group V) or unclassified (group U)...
December 5, 2016: Journal of Veterinary Cardiology: the Official Journal of the European Society of Veterinary Cardiology
https://www.readbyqxmd.com/read/27931985/impact-of-regulatory-measures-on-antipsychotics-drug-consumption-in-castilla-y-le%C3%A3-n-spain
#14
L H Martín Arias, C Treceño Lobato, S Pérez García, P García Ortega, M Sáinz Gil, R Sanz Fadrique, A Carvajal García-Pando
OBJECTIVES: Antipsychotics are currently used to treat different diseases; even some off-labelled conditions are treated with this medication. Consumption and cost of antipsychotic drugs sharply increased in Spain after second-generation drugs were marketed; several regulatory measures were adopted to curb this trend. The aim of this study was to examine the impact of these measures upon the use and cost of antipsychotics. STUDY DESIGN: Study of drug use (SDU) from 1995 to 2012...
December 2016: Public Health
https://www.readbyqxmd.com/read/27931299/association-of-allergy-immunology-and-obstructive-sleep-apnea
#15
Charles J Calais, Brian D Robertson, Douglas E Beakes
Obstructive sleep apnea (OSA) is characterized by repetitive upper airway collapse that results in nonrefreshing sleep, excessive daytime sleepiness, and, ultimately, adverse consequences on quality of life, the cardiovascular system, and neurocognitive performance. OSA has traditionally been linked to body habitus (obesity and increased neck circumference), racial demographics, alcohol, tobacco, and sedative use. Numerous other conditions are linked to OSA, which may have clinical relevance. Specifically, asthma and nasal obstructive syndromes, e...
November 2016: Allergy and Asthma Proceedings:
https://www.readbyqxmd.com/read/27931237/a-piperazidine-derivative-of-23-hydroxy-betulinic-acid-induces-a-mitochondria-derived-ros-burst-to-trigger-apoptotic-cell-death-in-hepatocellular-carcinoma-cells
#16
Nan Yao, Ying-Jie Li, Yu-He Lei, Nan Hu, Wei-Min Chen, Zhe Yao, Miao Yu, Jun-Shan Liu, Wen-Cai Ye, Dong-Mei Zhang
BACKGROUND: Elevated production of reactive oxygen species (ROS) and an altered redox state have frequently been observed in hepatocellular carcinoma (HCC); therefore, selective killing of HCC cells by chemotherapeutic agents that stimulate ROS generation or impair antioxidant systems may be a feasible approach in HCC chemotherapy. Recently, betulinic acid and its derivatives have attracted attention because they showed anti-cancer effects via a ROS- and mitochondria-related mechanism...
December 8, 2016: Journal of Experimental & Clinical Cancer Research: CR
https://www.readbyqxmd.com/read/27930332/state-estimation-and-prediction-using-clustered-particle-filters
#17
Yoonsang Lee, Andrew J Majda
Particle filtering is an essential tool to improve uncertain model predictions by incorporating noisy observational data from complex systems including non-Gaussian features. A class of particle filters, clustered particle filters, is introduced for high-dimensional nonlinear systems, which uses relatively few particles compared with the standard particle filter. The clustered particle filter captures non-Gaussian features of the true signal, which are typical in complex nonlinear dynamical systems such as geophysical systems...
December 5, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27929684/acute-effects-of-snus-in-never-tobacco-users-a-pilot-study
#18
Jenny E Ozga, Nicholas J Felicione, Daniel Elswick, Melissa D Blank
BACKGROUND: Snus tobacco characteristics may attract non-tobacco users, including relatively low, but pharmacologically active, doses of nicotine. Lower nicotine doses may limit adverse drug effects while also producing a physiologically active response. OBJECTIVES: This pilot study is the first to profile the acute effects of snus on physiological and subjective assessments in a sample of never-tobacco users. METHODS: Eleven never-tobacco users (five women; <100 uses/lifetime) were recruited from the community via university-approved advertisements...
December 8, 2016: American Journal of Drug and Alcohol Abuse
https://www.readbyqxmd.com/read/27929496/experimental-evaluation-of-a-gpu-based-monte-carlo-dose-calculation-algorithm-in-the-monaco-treatment-planning-system
#19
Moti R Paudel, Anthony Kim, Arman Sarfehnia, Sayed B Ahmad, David J Beachey, Arjun Sahgal, Brian M Keller
A new GPU-based Monte Carlo dose calculation algorithm (GPUMCD), devel-oped by the vendor Elekta for the Monaco treatment planning system (TPS), is capable of modeling dose for both a standard linear accelerator and an Elekta MRI linear accelerator. We have experimentally evaluated this algorithm for a standard Elekta Agility linear accelerator. A beam model was developed in the Monaco TPS (research version 5.09.06) using the commissioned beam data for a 6 MV Agility linac. A heterogeneous phantom representing several scenarios - tumor-in-lung, lung, and bone-in-tissue - was designed and built...
November 8, 2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/27929162/a-driving-force-for-polypeptide-and-protein-collapse
#20
Antonello Merlino, Nicola Pontillo, Giuseppe Graziano
Experimental measurements and computational results have shown that polypeptide chains, made up of 15-25 glycine residues, collapse to compact structures in water at room temperature. This contrasts with the classic idea that the burial of nonpolar side chains, i.e., the hydrophobic effect, is the driving force of collapse and folding of polypeptides and proteins. It is thus necessary to find a different driving force for polyglycine collapse. The present study aims at showing that the hydrophobic effect has to be re-defined in terms of decrease in solvent-excluded volume associated with chain collapse so that it is characterized by a gain in translational entropy of water molecules...
December 8, 2016: Physical Chemistry Chemical Physics: PCCP
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