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William W Parson
Rate constants for photochemical charge separation and recombination in a zinc-porphyrin-benzoquinone cyclophane are calculated by an approach that was developed recently to include effects of vibrational dephasing and relaxation and to reduce the dependence on freely adjustable parameters. The theory is extended to treat the rate of vibrational relaxation individually for each vibrational sublevel of the initial charge-transfer product. Quantum-mechanical/molecular-mechanical simulations of the reactions in iso-octane, toluene, dichloromethane and acetonitrile suggest that charge separation occurs at conical intersections in the two more polar solvents, but at avoided crossings in the nonpolar solvents...
March 20, 2018: Journal of Physical Chemistry. B
Balaram Mohapatra, Pinaki Sar, Sufia Khannam Kazy, Mrinal Kumar Maiti, Tulasi Satyanarayana
Reductive transformation of toxic arsenic (As) species by As reducing bacteria (AsRB) is a key process in As-biogeochemical-cycling within the subsurface aquifer environment. In this study, we have characterized a Gram-stain-negative, non-spore-forming, rod-shaped As reducing bacterium designated KAs 5-3T, isolated from highly As-contaminated groundwater of India. Strain KAs 5-3T displayed high 16S rRNA gene sequence similarity to the members of the genus Pseudoxanthomonas, with P. mexicana AMX 26BT (99.25% similarity), P...
2018: PloS One
Florian Junne, Martina Michaelis, Eva Rothermund, Felicitas Stuber, Harald Gündel, Stephan Zipfel, Monika A Rieger
Objectives : This study analyses the perceived relevance of stress-dimensions in work-settings from the differential views of Human Resource Managers (HRM), Occupational Physicians (OP), Primary Care Physicians (PCP) and Psychotherapists (PT) in Germany. Methods : Cross-sectional study design, using a self-report questionnaire. Descriptive measures and explorative bivariate methods were applied for group-comparisons. Results are presented as rankings of perceived importance and as polarity profiles of contrasting views...
March 20, 2018: International Journal of Environmental Research and Public Health
Flavio Esposito, Rajeev Ranjan, Stefania Campopiano, Agostino Iadicicco
In this work, we report about our recent results concerning the fabrication of Long Period Grating (LPG) sensors in several optical fibers, through the Electric Arc Discharge (EAD) technique. In particular, the following silica fibers with both different dopants and geometrical structures are considered: standard Ge-doped, photosensitive B/Ge codoped, P-doped, pure-silica core with F-doped cladding, Panda type Polarization-maintaining, and Hollow core Photonic crystal fiber. An adaptive platform was developed and the appropriate "recipe" was identified for each fiber, in terms of both arc discharge parameters and setup arrangement, for manufacturing LPGs with strong and narrow attenuation bands, low insertion losses, and short length...
March 20, 2018: Sensors
Chunxue Hao, Bochong Wang, Fusheng Wen, Congpu Mu, Jianyong Xiang, Lei Li, Zhongyuan Liu
Through a facile self-assembled process, an ultralight reduced graphene oxide/black phosphorus (rGO/BP) composite aerogel was successfully fabricated. The BP nanosheets were homogeneously distributed throughout the rGO 3D framework, and the interfaces between rGO and BP possessed four kinds of interconnections, such as wrapping, wearing, bridging and weak linking. As an ultralight composite, the rGO/BP aerogel could easily stand on the stamen of a flower. Compared with pure rGO aerogel, the rGO/BP composite aerogel exhibited enhanced microwave absorption ability...
March 20, 2018: Nanotechnology
HongYing Mei, Wen Xu, Chao Wang, HaiFeng Yuan, Chao Zhang, Lan Ding, Jin Zhang, Chao Deng, YiFan Wang, Francois M Peeters
Magneto-optical (MO) properties of bi- and tri-layer graphene are investigated utilizing terahertz time-domain spectroscopy (THz TDS) in the presence of a strong magnetic fleld at room-temperature. In the Faraday conflguration and applying optical polarization measurements, we measure the real and imaginary parts of the longitudinal and transverse MO conductivities of difierent graphene samples. The obtained experimental data flt very well with the well-known MO Drude formula, from which we obtain key sample and material parameters of bi- and tri-layer graphene, such as the electron efiective mass, the
 electronic relaxation time and the electron density...
March 20, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Yuli Wei, Jiasong Fang, Yunping Xu, Weiqiang Zhao, Junwei Cao
A novel heterotrophic, Gram-stain-positive, facultatively anaerobic and rod-shaped bacterium, designated strain NBT06-6T , was isolated from the deep seawater in the New Britain Trench and characterized phylogenetically and phenotypically. Optimal bacterial growth occurred at 35 °C (range 22-41 °C), at pH 6 (4-8) and with 4 % (w/v) NaCl (0-10 %). The strain grew at hydrostatic pressures of 0.1-100 MPa (optimum, 0.1 MPa) at 35 °C. Phylogenetic analysis of the 16S rRNA gene sequences indicated that strain NBT06-6T belonged to the genus Corynebacterium, with the highest sequence similarity (97...
March 20, 2018: International Journal of Systematic and Evolutionary Microbiology
Kim Ngan Tran, Jong-Il Choi
PURPOSE: To study gene expression modulation in response to continuous whole-body exposure to low-dose-rate gamma radiation and improve our understanding of the mechanism of this impact at the molecular basis. MATERIALS AND METHODS: cDNA microarray method with complete pooling of samples was used to study expression changes in the transcriptome profile of livers from rats treated with prolonged low-dose-rate ionizing radiation relative to that of sham-irradiated rats...
March 20, 2018: International Journal of Radiation Biology
Min Zhou, Qunhong Weng, Zakhar I Popov, Yijun Yang, Liubov Yu Antipina, Pavel B Sorokin, Xi Wang, Yoshio Bando, Dmitri Golberg
Electrocatalytic hydrogen evolution reaction (HER) in alkaline solution is hindered by its sluggish kinetics toward water dissociation. Nickel-based catalysts, as low-cost and effective candidates, show great potentials to replace platinum (Pt)-based materials in the alkaline media. The main challenge regarding this type of catalysts is their relatively poor durability. In this work, we conceive and construct a charge-polarized carbon layer derived from carbon quantum dots (CQDs) on Ni3 N nanostructure (Ni3 N@CQDs) surfaces, which simultaneously exhibit durable and enhanced catalytic activity...
March 20, 2018: ACS Nano
Yoshito Tobe
Three isomers of quinodimethanes (QDMs) adopt different electronic configurations and geometries, generating their own characteristic physical properties. Incorporation of QDMs into non-benzenoid aromatic or antiaromatic frameworks not only planarizes the whole π system optimizing conjugation, but also changes the electronic properties inherent to QDMs, sometimes drastically, due to the topology of the π system, through interaction with the remaining part of the molecules. In non-benzenoid systems, molecular orbital levels and orbital distribution are uneven compared to benzenoid systems, thereby polarizing the ground state and leading to unique behavior in excited states...
March 20, 2018: Topics in Current Chemistry (Journal)
Vidhika Punjani, Golam Mohiuddin, Supreet Kaur, Raj Kumar Khan, Sharmistha Ghosh, Santanu Kumar Pal
A new approach accompanied by superstructural frustration is reported. By attaching a cholesterol moiety directly to the central bent-core system it displayed exotic BPIII, BPII/I, Ncyb*, TGBA, SmAPA, SmA and SmX phases as shown by X-ray scattering results. While higher homologues of the series exhibited spontaneous formation of polar order (Ps ∼ 61 nC cm-2) upon applied voltage, the lower homologues showed thermochromic behaviour which can also be trapped via temperature quenching.
March 20, 2018: Chemical Communications: Chem Comm
Juan Ramón Avilés-Moreno, Giel Berden, Jos Oomens, Bruno Martínez-Haya
Proton bonding drives the supramolecular chemistry of a broad range of materials with polar moieties. Proton delocalization and electronic charge redistribution have a profound impact on the structure of proton-bound molecular frameworks, and pose fundamental challenges to quantum chemical modelling. This study provides insights into the structural and spectral signatures of the intramolecular proton bond formed in a benchmark polyazamacrocycle anionophore (cyclen, 1,4,7,10-tetraazacyclododecane). Infrared action spectroscopy is employed to characterize the macrocycle, isolated in protonated form...
March 20, 2018: Physical Chemistry Chemical Physics: PCCP
Addisu Alemayehu Assegie, Ju-Hsiang Cheng, Li-Ming Kuo, Wei-Nien Su, Bing-Joe Hwang
The practical implementation of an anode-free lithium-metal battery with promising high capacity is hampered by dendrite formation and low coulombic efficiency. Most notably, these challenges stem from non-uniform lithium plating and unstable SEI layer formation on the bare copper electrode. Herein, we revealed the homogeneous deposition of lithium and effective suppression of dendrite formation using a copper electrode coated with a polyethylene oxide (PEO) film in an electrolyte comprising 1 M LiTFSI, DME/DOL (1/1, v/v) and 2 wt% LiNO3...
March 20, 2018: Nanoscale
Xin Zhang, Xiaoli Wang, Qinglin Wang, Xinjun Ma, Chunming Liu, Peifang Li, Cailong Liu, Yonghao Han, Yanzhang Ma, Chunxiao Gao
Hydride ions (H-) have an appropriate size for fast transport, which makes the conduction of H- attractive. In this work, the H- transport properties of BaH2 have been investigated under pressure using in situ impedance spectroscopy measurements up to 11.2 GPa and density functional theoretical calculations. The H- transport properties, including ionic migration resistance, relaxation frequency, and relative permittivity, change significantly with pressure around 2.3 GPa, which can be attributed to the structural phase transition of BaH2...
March 20, 2018: Physical Chemistry Chemical Physics: PCCP
Kristof M Bal, Erik C Neyts
A number of recent computational material design studies based on density functional theory (DFT) calculations have put forward a new class of materials with electrically switchable chemical characteristics that can be exploited in the development of tunable gas storage and electrocatalytic applications. We find systematic flaws in almost every computational study of gas adsorption on polarized or charged surfaces, stemming from an improper and unreproducible treatment of periodicity, leading to very large errors of up to 3 eV in some cases...
March 20, 2018: Physical Chemistry Chemical Physics: PCCP
Yen-Chen Shih, Leeyih Wang, Hsiao-Chi Hsieh, King-Fu Lin
Ion accumulation of organometal halide perovskite (OHP) induced by electrode polarization of perovskite solar cells (PSCs) under illumination has been intensely studied and associated with widely observed current-voltage hysteresis behavior. This work dedicates to the investigation of charged species' behavior at the compact TiO2/OHP interface with respect to electrode polarization in PSC devices. By providing a comprehensive discussion of open-circuit voltage (VOC) buildup and VOC decay under illumination and in the dark for the PSCs modified with [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) at the TiO2/OHP interface and their corresponding electrochemical impedance spectroscopies (EIS), a justified mechanism is proposed attempting to elucidate the dynamics of interfacial species with respect to the time and frequency domains...
March 20, 2018: ACS Applied Materials & Interfaces
Abdullah Alsubaie, Pankaj Sharma, Jin Hong Lee, Jeong Yong Kim, Chan-Ho Yang, Jan Seidel
We investigate the effect of variable uniaxial tensile strain on the evolution of 71° ferroelastic domains in (001)-oriented epitaxial BiFeO3 (BFO) thin films using piezoresponse force microscopy (PFM). For this purpose, a newly designed bending stage has been employed which allows for tensile bending as wells as in-situ PFM characterization. In-situ PFM imaging reveals polarization-strain correlations at the nanoscale. Specifically, ferroelastic domains with in-plane polarization along the direction of applied tensile strain expand, while the adjoining domains with orthogonal in-plane polarization contract...
March 20, 2018: ACS Applied Materials & Interfaces
Joachim Janda, Karsten Nödler, Heinz-Jürgen Brauch, Christian Zwiener, Frank T Lange
A simple and robust analytical method for the determination of perfluorinated carboxylic acids (PFCAs) with C2 to C8 chains, based on solid-phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), was developed, validated and applied to tap water, groundwater and surface water. Two stationary phases for LC (Obelisc N and Kinetex C18 ) and two materials with weak anion-exchange properties for SPE (Strata X-AW and Oasis WAX) were evaluated. Robust separation and retention was achieved with the reversed phase column and an acidic eluent...
March 19, 2018: Environmental Science and Pollution Research International
Vina Ps Tan, Heather M Macdonald, Leigh Gabel, Heather A McKay
Physical activity is essential for optimal bone strength accrual, but we know little about interactions between physical activity, sedentary time, and bone outcomes in older adolescents. Physical activity (by accelerometer and self-report) positively predicted bone strength and the distal and midshaft tibia in 15-year-old boys and girls. Lean body mass mediated the relationship between physical activity and bone strength in adolescents. PURPOSE: To examine the influence of physical activity (PA) and sedentary time on bone strength, structure, and density in older adolescents...
March 20, 2018: Archives of Osteoporosis
Philip L Richardson, Ewan D Wakefield, Richard A Phillips
Background: Albatrosses and other large seabirds use dynamic soaring to gain sufficient energy from the wind to travel large distances rapidly and with little apparent effort. The recent development of miniature bird-borne tracking devices now makes it possible to explore the physical and biological implications of this means of locomotion in detail. Here we use GPS tracking and concurrent reanalyzed wind speed data to model the flight performance of wandering albatrosses Diomedea exulans soaring over the Southern Ocean...
2018: Movement Ecology
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