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Marc Serra-Garcia, Valerio Peri, Roman Süsstrunk, Osama R Bilal, Tom Larsen, Luis Guillermo Villanueva, Sebastian D Huber
The modern theory of charge polarization in solids is based on a generalization of Berry's phase. The possibility of the quantization of this phase arising from parallel transport in momentum space is essential to our understanding of systems with topological band structures. Although based on the concept of charge polarization, this same theory can also be used to characterize the Bloch bands of neutral bosonic systems such as photonic or phononic crystals. The theory of this quantized polarization has recently been extended from the dipole moment to higher multipole moments...
January 15, 2018: Nature
Wesley Richard Browne, Juan Chen, Apparao Draksharapu, Maja Gruden, Stepan Stepanovic
The non-heme (L)FeIII and (L)FeIII-O-FeIII(L) complexes (L = 1,1-di(pyridin-2-yl)-N,N-bis(pyridin-2-ylmethyl)ethan-1-amine) undergoes reduction under irradiation to the FeII state with concomitant oxidation of methanol to methanal, without the need for a secondary photosensitizer. Spectroscopic and Density Functional Theory (DFT) studies support a mechanism in which irradiation results in charge transfer excitation of a FeIII--O-FeIII complex to generate [(L)FeIV=O]2+ (observed transiently during irradiation in acetonitrile), and an equivalent of LFeII...
January 15, 2018: Angewandte Chemie
João R Vale, Tatu Rimpiläinen, Elina Sievanen, Kari Rissanen, Carlos A M Afonso, Nuno R Candeias
The autooxidative condensation of 2-aryl-2-lithio-1,3-dithianes is here reported. Treatment of 2-aryl-1,3-dithianes with n-BuLi in the absence of any electrophile leads to condensation of three molecules of 1,3-dithianes and formation of highly functionalized α-thioether ketones orthothioesters in 51-89% yields upon air exposure. The method was further expanded to benzaldehyde dithioacetals, affording corresponding orthothioesters and α-thioether ketones in 48-97% yields. The experimental results combined with density functional theory studies support a mechanism triggered by the autooxidation of 2-aryl-2-lithio-1,3-dithianes to yield a highly reactive thioester that undergoes condensation with two other molecules of 2-aryl-2-lithio-1,3-dithiane...
January 15, 2018: Journal of Organic Chemistry
Erik Andris, Prokopis Andrikopoulos, Jiří Schulz, Jan Turek, Aleš Růžička, Jana Roithová, Lubomír Rulíšek
Attractive metallophilic (aurophilic, argentophilic, cuprophilic, …) interactions play an important role in arrangement and stabilization of oligonuclear metal ion complexes. We report a combined experimental and theoretical assessment of aurophilic interactions in closed-shell gold(I) dimers. The experimental binding energies were obtained for charged [(LH)AuCl]+…[(L')AuCl] dimers (L is either a phosphine or a N-heterocyclic carbene ligand) in the gas phase. These energies served for benchmarking of correlated quantum chemical calculations (CCSD(T)-calibrated SCS-MP2/CBS method) that were then applied to neutral [(L)AuX]…[(L')AuX] dimers (X = Cl, Br, I)...
January 15, 2018: Journal of the American Chemical Society
Cene Fišer, Christopher T Robinson, Florian Malard
The species concept is the cornerstone of biodiversity science and any paradigm shift in the delimitation of species affects many research fields. Many biologists now are embracing a new 'species' paradigm as separately evolving populations using different delimitation criteria. Individual criteria can emerge during different periods of speciation; some may never evolve. As such, a paradigm shift in the species concept relates to this inherent heterogeneity in the speciation process and species category - which is fundamentally overlooked in biodiversity research...
January 15, 2018: Molecular Ecology
Matthias Meier, Zdeněk Jakub, Jan Balajka, Jan Hulva, Roland Bliem, Pardeep K Thakur, Tien-Lin Lee, Cesare Franchini, Michael Schmid, Ulrike Diebold, Francesco Allegretti, David A Duncan, Gareth S Parkinson
Accurately modelling the structure of a catalyst is a fundamental prerequisite for correctly predicting reaction pathways, but a lack of clear experimental benchmarks makes it difficult to determine the optimal theoretical approach. Here, we utilize the normal incidence X-ray standing wave (NIXSW) technique to precisely determine the three dimensional geometry of Ag1 and Cu1 adatoms on Fe3O4(001). Both adatoms occupy bulk-continuation cation sites, but with a markedly different height above the surface (0.43 ± 0...
January 15, 2018: Nanoscale
Heidi K Norton, Daniel J Emerson, Harvey Huang, Jesi Kim, Katelyn R Titus, Shi Gu, Danielle S Bassett, Jennifer E Phillips-Cremins
Mammalian genomes are folded in a hierarchy of compartments, topologically associating domains (TADs), subTADs and looping interactions. Here, we describe 3DNetMod, a graph theory-based method for sensitive and accurate detection of chromatin domains across length scales in Hi-C data. We identify nested, partially overlapping TADs and subTADs genome wide by optimizing network modularity and varying a single resolution parameter. 3DNetMod can be applied broadly to understand genome reconfiguration in development and disease...
January 15, 2018: Nature Methods
Anatolii Mokshin, Bulat N Galimzyanov
The dynamic structure factor is the quantity, which can be measured by means of Brillouin light-scattering as well as by means of inelastic scattering of neutrons and X-rays. The spectral (or frequency) moments of the dynamic structure factor define directly the sum rules of the scattering law. The theoretical scheme formulated in this study allows one to describe the dynamics of local density fluctuations in simple liquids and to obtain the expression of the dynamic structure factor in terms of the spectral moments...
January 15, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Daniel Fritsch
Spinel ferrites in general show a rich interplay of structural, electronic, and magnetic properties. Here, we particularly focus on zinc ferrite (ZFO), which has been observed experimentally to crystallise in the cubic <i>normal</i> spinel structure. However, its magnetic ground state is still under dispute. In addition, some unusual magnetic properties in ZFO thin films or nanostructures have been explained by a possible partial cation inversion and a different magnetic interaction between the two cation sublattices of the spinel structure compared to the crystalline bulk material...
January 15, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Dhamodharan Prabhu, Sundaraj Rajamanikandan, Mathimaran Amala, Surekha Kanagarajan, Jeyaraman Jeyakanthan
Lymphatic filariasis is a debilitating vector borne parasitic disease that infects human lymphatic system by nematode Brugia malayi. Currently available anti-filarial drugs are effective only on the larval stages of parasite. So far, no effective drugs are available for humans to treat filarial infections. In this regard, aspartate semialdehyde dehydrogenase (ASDase) in lysine biosynthetic pathway from Wolbachia endosymbiont Brugia malayi represents an attractive therapeutic target for the development of novel anti-filarial agents...
January 15, 2018: Journal of Biomolecular Structure & Dynamics
Chenrong Huang, Ziteng Wang, Linsheng Liu, Xiaoxue Liu, Ji Dong, Qingqing Xu, Bin Zhang, Liyan Miao
The purpose of this study was to measure dopamine D2/3 receptor occupancy (RO) as a marker of the clinical efficacy of ropinirole in rats via positron emission tomography (PET) using 18F-fallypride as the radiotracer and to explore the relationship between dopamine RO and the plasma concentration of ropinirole via pharmacokinetic-pharmacodynamic modeling. Plasma was collected from 16 rats treated with one of four doses of ropinirole. For the time-dependent study, the data of 16 rats in the 15 mg/kg dose group at four time points were averaged, and another 24 rats were divided into three dose groups (5 mg/kg, 30 mg/kg and 60 mg/kg) for the dose-dependent study; the animals were assessed via 18F-fallypride PET scans...
January 15, 2018: Xenobiotica; the Fate of Foreign Compounds in Biological Systems
Sara Albuquerque, Anneli Eriksson, Helle M Alvesson
BACKGROUND: Low retention of humanitarian workers poses constraints on humanitarian organisations' capacity to respond effectively to disasters. Research has focused on reasons for humanitarian workers leaving the sector, but little is known about the factors that can elucidate long-term commitment. OBJECTIVE: To understand what motivates and supports experienced humanitarian health workers to remain in the sector. METHODS: Semi-structured interviews were conducted with 10 experienced nurses who had been on at least three field missions with Médecins Sans Frontières Sweden...
2018: Global Health Action
Hong Ma, Yanyan Chen, Zhihong Wei, Sen Wang, Zhangfeng Qin, Mei Dong, Junfen Li, Jianguo Wang, Weibin Fan
Although dienes or trienes have been shown to be possible precursors for cyclization, direct cyclization of alkenes or alkoxides has not been systematically studied yet. Thus, the reaction mechanism of cyclization of linear alkenes was investigated here with H-ITQ-13 by density functional theory considering dispersive interactions (DFT-D). The similar free energy of different linear alkoxides of the same carbon number suggests that they can co-exist in the H-ITQ-13 intersection at 673.15 K during MTO process...
January 15, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Hui Li, Qi Li, Peng Wen, Trey B Williams, Shiba Adhikari, Chaochao Dun, Chang Lu, Dominique Itanze, Lin Jiang, David L Carroll, George L Donati, Pamela M Lundin, Yejun Qiu, Scott M Geyer
Highly efficient and stable electrocatalysts, particularly those that are capable of multifunctionality in the same electrolyte, are in high demand for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). In this work, highly monodisperse CoP and Co2 P nanocrystals (NCs) are synthesized using a robust solution-phase method. The highly exposed (211) crystal plane and abundant surface phosphide atoms make the CoP NCs efficient catalysts toward ORR and HER, while metal-rich Co2 P NCs show higher OER performance owing to easier formation of plentiful Co2 P@COOH heterojunctions...
January 15, 2018: Advanced Materials
Zao Wang, Huitong Du, Zhiang Liu, Hui Wang, Abdullah M Asiri, Xuping Sun
It is of great importance to design and develop highly active electrocatalysts for the hydrogen evolution reaction (HER) under alkaline conditions. In this work, we report the development of a CeO2-Cu3P nanoarray supported on nickel foam (CeO2-Cu3P/NF) as an excellent HER catalyst with the demand of an overpotential of only 148 mV to deliver a geometrical catalytic current density of 20 mA cm-2 in 1.0 M KOH. Remarkably, this catalyst also shows strong long-term electrochemical durability for at least 100 h with nearly 100% Faradaic efficiency...
January 15, 2018: Nanoscale
Anthony Yoshimura, Michael Lamparski, Neerav Kharche, Vincent Meunier
Electron beam irradiation by transmission electron microscopy (TEM) is a common and effective method for post-synthesis defect engineering in two-dimensional transition metal dichalcogenides (TMDs). Combining density functional theory (DFT) with relativistic scattering theory, we simulate the generation of such defects in monolayer group-VI TMDs, MoS2, WS2, MoSe2, and WSe2, focusing on two fundamental TEM-induced atomic displacement processes: chalcogen sputtering and chalcogen vacancy migration. Our calculations show that the activation energies of chalcogen sputtering depend primarily on the chalcogen species, and are smaller in selenides than in sulfides...
January 15, 2018: Nanoscale
Maristella Alessio, Florian A Bischoff, Joachim Sauer
A hybrid QM:QM method that combines MP2 as high-level method on cluster models with density functional theory (PBE+D2) as low-level method on periodic models is applied to adsorption of methane and ethane on the MgO(001) surface for which reliable experimental desorption enthalpies are available. Two coverages are considered, monolayer (every second Mg2+ ion occupied) and one quarter coverage (one of eight Mg2+ ions occupied). Structure optimizations are performed at the hybrid MP2:(PBE+D2) level, with the MP2 energies and forces counterpoise corrected for basis set superposition error and extrapolated to the complete basis set limit...
January 15, 2018: Physical Chemistry Chemical Physics: PCCP
Lisa M Warner, Gertraud Stadler, Janina Lüscher, Nina Knoll, Sibylle Ochsner, Rainer Hornung, Urte Scholz
OBJECTIVE: In social-cognitive theory, it is hypothesized that mastery experiences (successfully implementing behaviour change) are a source of self-efficacy, and self-efficacy increases the opportunity for experiencing mastery. Vicarious experiences (seeing others succeed) are suggested as another source of self-efficacy. However, the hypothesis of this reciprocal relationship has not been tested using a day-to-day design. DESIGN: This article reports findings from two intensive longitudinal studies, testing the reciprocal relationship of self-efficacy and its two main sources within the naturally occurring process of quitting smoking (without intervention)...
January 15, 2018: British Journal of Health Psychology
Mingchuan Luo, Yingjun Sun, Xu Zhang, Yingnan Qin, Mingqiang Li, Yingjie Li, Chunji Li, Yong Yang, Lei Wang, Peng Gao, Gang Lu, Shaojun Guo
Selectively exposing active surfaces and judiciously tuning the near-surface composition of electrode materials represent two prominent means of promoting electrocatalytic performance. Here, a new class of Pt3 Fe zigzag-like nanowires (Pt-skin Pt3 Fe z-NWs) with stable high-index facets (HIFs) and nanosegregated Pt-skin structure is reported, which are capable of substantially boosting electrocatalysis in fuel cells. These unique structural features endow the Pt-skin Pt3 Fe z-NWs with a mass activity of 2.11 A mg-1 and a specifc activity of 4...
January 15, 2018: Advanced Materials
Thankan Jayasekharan, Shyam L Gupta, Vikas Dhiman
The intrinsic binding ability of seven natural peptides (oxytocin, arg8 -vasopressin, bradykinin, angiotensin-I, substance-P, somatostatin, and neurotensin) with copper in two different oxidation states (CuI/II ) derived from different Cu+/2+ precursor sources have been investigated for their charge dependent binding characteristics. The peptide-CuI/II complexes, [M - (n-1)H + nCuI ] and [M - (2n-1)H + nCuII ] are prepared/generated by the reaction of peptides with CuI solution/Cu-target and CuSO4 solution, and are analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS)...
January 15, 2018: Journal of Mass Spectrometry: JMS
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