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Ranjith Bose, Zhenyu Jin, Seokhee Shin, Sungjoon Kim, Sun Young Lee, Yo-Sep Min
MoS2 is a promising material to replace Pt catalyst for electrochemical hydrogen evolution reaction (HER). It is well known that the activity of the MoS2 catalyst in the HER is significantly promoted by doping cobalt atoms. Recently, the Co-Mo-S phase, in which cobalt atoms decorate the edge positions of the MoS2 slabs, has been identified as a co-catalytic phase in the Co-doped MoS2 (Co-MoSx) with a low Co content. Here, we report the effect of the incorporation of cobalt atoms on the chemical state of Co-MoSx catalyst which gives rise to the co-catalytic effect...
May 25, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Henrik Eickhoff, Lorenzo Toffoletti, Wilhelm Klein, Gabriele Raudaschl-Sieber, Thomas F Fässler
The lithium phosphidosilicates Li10Si2P6 and Li3Si3P7 are obtained by high-temperature reactions of the elements or including binary Li-P precursors. Li10Si2P6 (P21/n, Z = 2, a = 7.2051(4) Å, b = 6.5808(4) Å, c = 11.6405(7) Å, β = 90.580(4)°) features edge-sharing SiP4 double tetrahedra forming [Si2P6](10-) units with a crystal structure isotypic to Na10Si2P6 and Na10Ge2P6. Li3Si3P7 (P21/m, Z = 2, a = 6.3356(4) Å, b = 7.2198(4) Å, c = 10.6176(6) Å, β = 102.941(6)°) crystallizes in a new structure type, wherein SiP4 tetrahedra are linked via common vertices and which are further connected by polyphosphide chains to form unique ∞(2)[Si3P7](3-) double layers...
May 24, 2017: Inorganic Chemistry
Igor Olaciregui-Ruiz, Roel Rozendaal, René F M van Oers, Ben Mijnheer, Anton Mans
PURPOSE: At our institute, a transit back-projection algorithm is used clinically to reconstruct in vivo patient and in phantom 3D dose distributions using EPID measurements behind a patient or a polystyrene slab phantom, respectively. In this study, an extension to this algorithm is presented whereby in air EPID measurements are used in combination with CT data to reconstruct 'virtual' 3D dose distributions. By combining virtual and in vivo patient verification data for the same treatment, patient-related errors can be separated from machine, planning and model errors...
May 2017: Physica Medica: PM
M R López-Álvarez, M Salze, A Cenier, C Robinson, R Paillot, A S Waller
Streptococcus equi subsp. equi (S. equi) is the causative agent of strangles, one of the most frequently diagnosed infectious diseases of horses worldwide. Phospholipase A2 toxins (PLA2) cleave phospholipid molecules at position sn-2 contributing to the production of leukotrienes that are important inflammatory mediators. Two homologous phospholipases, SlaA and SlaB are encoded by the S. equi genome suggesting that PLA2 toxins may contribute to its pathogenicity. Here we report the immunogenicity and role of PLA2 toxins during natural and experimental infection of horses with S...
May 2017: Veterinary Microbiology
Sina Saravi, Thomas Pertsch, Frank Setzpfandt
We propose the use of nonlinear periodic waveguides for direct and fully integrated generation of counterpropagating photon pairs by spontaneous parametric down-conversion. Using the unique properties of Bloch modes in such periodic structures, we furthermore show that two counterpropagating phase-matching conditions can be fulfilled simultaneously, allowing for the generation of path-entangled Bell states in a single periodic waveguide. To demonstrate the feasibility of our proposal, we design a photonic crystal slab waveguide made of lithium niobate and numerically demonstrate Bell-state generation...
May 5, 2017: Physical Review Letters
Tao Yang, Ryoichi Fukuda, Saburo Hosokawa, Tsunehiro Tanaka, Shigeyoshi Sakaki, Masahiro Ehara
Single-atom catalysts have attracted much interest recently because of their excellent stability, high catalytic activity, and remarkable atom efficiency. Inspired by the recent experimental discovery of a highly efficient single-atom catalyst Pd1/γ-Al2O3, we conducted a comprehensive DFT study on geometries, stabilities and CO oxidation catalytic activities of M1/γ-Al2O3 (M=Pd, Fe, Co, and Ni) by using slab-model. One of the most important results here is that Ni1/Al2O3 catalyst exhibits higher activity in CO oxidation than Pd1/Al2O3...
April 7, 2017: ChemCatChem
Katharina Doblhoff-Dier, Joerg Meyer, Philip E Hoggan, Geert-Jan Kroes
Accurate modeling of heterogeneous catalysis requires the availability of highly accurate potential energy surfaces. Within density functional theory, these can - unfortunately - depend heavily on the exchange-correlation functional. High-level ab-initio calculations, on the other hand, are challenging due to the system size and the metallic character of the metal slab. Here, we present a quantum Monte Carlo (QMC) study of the reaction barrier for the benchmark system H2+Cu(111), focusing on the dissociative chemisorption barrier height...
May 17, 2017: Journal of Chemical Theory and Computation
Thomas Friedrich Fässler, Antti J Karttunen, Laura-Alice Jantke
The large interest in novel Si allotropes has led to an intense investigation of tetrahedral framework structures during the last years. Recently, a guide to deriving sp3-Si allotropes from atom slabs of the diamond structure enabled a systematic deduction of several low-density modifications. Some of the Si networks were recognized as experimentally known frameworks - so-called chemi-inspired structures. We herein present nine novel Si by modifying three-atom thick slabs of the cubic diamond structure after their smooth distortion by applying the same construction kit...
May 17, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Gerben Schepers, Douwe J J van Hinsbergen, Wim Spakman, Martha E Kosters, Lydian M Boschman, Nadine McQuarrie
At two trench segments below the Andes, the Nazca Plate is subducting sub-horizontally over ∼200-300 km, thought to result from a combination of buoyant oceanic-plateau subduction and hydrodynamic mantle-wedge suction. Whether the actual conditions for both processes to work in concert existed is uncertain. Here we infer from a tectonic reconstruction of the Andes constructed in a mantle reference frame that the Nazca slab has retreated at ∼2 cm per year since ∼50 Ma. In the flat slab portions, no rollback has occurred since their formation at ∼12 Ma, generating 'horse-shoe' slab geometries...
May 16, 2017: Nature Communications
M B Miran, A A Kasuku, E S Swai
AIM: Echinococcosis or hydatidosis (due to the larval stage of Echinococcus spp.) and cysticercosis (due to the larval stage of Taenia hydatigena) pose a significant economic losses due to slaughter condemnation and risk to public health in developing countries such as Tanzania where sanitation is poor and people live in close proximity with each other and with animals. This study was conducted to determine the prevalence of and to identify the predisposing factors for echinococcosis and cysticercosis in sheep and goats at three slaughter slabs located in the livestock-wildlife interface areas of Ngorongoro, Tanzania...
April 2017: Veterinary World
L Harbour, M W C Dharma-Wardana, D D Klug, L J Lewis
Using the two-temperature model for ultrafast matter (UFM), we compare the equation of state, pair-distribution functions g(r), and phonons using the neutral pseudoatom (NPA) model with results from density functional theory (DFT) codes and molecular dynamics (MD) simulations for Al, Li, and Na. The NPA approach uses state-dependent first-principles pseudopotentials from an "all-electron" DFT calculation with finite-T exchange-correlation functional (XCF). It provides pair potentials, structure factors, the "bound" and "free" states, as well as a mean ionization Z[over ¯] unambiguously...
April 2017: Physical Review. E
Farzad Zangeneh-Nejad, Amin Khavasi
In this contribution a new approach to perform spatial integration is presented using a dielectric slab. Our approach is indeed based on the fact that the transmission coefficient of a simple dielectric slab at its mode excitation angle matches the Fourier-Green's function of first-order integration. Inspired by the mentioned dielectric-based integrator, we further demonstrate its graphene-based counterpart. The latter is not only reconfigurable but also highly miniaturized in contrast to the previously reported designs [Opt...
May 15, 2017: Optics Letters
Thomas P Ferrand, Nadège Hilairet, Sarah Incel, Damien Deldicque, Loïc Labrousse, Julien Gasc, Joerg Renner, Yanbin Wang, Harry W Green Ii, Alexandre Schubnel
Intermediate-depth earthquakes (30-300 km) have been extensively documented within subducting oceanic slabs, but their mechanics remains enigmatic. Here we decipher the mechanism of these earthquakes by performing deformation experiments on dehydrating serpentinized peridotites (synthetic antigorite-olivine aggregates, minerals representative of subduction zones lithologies) at upper mantle conditions. At a pressure of 1.1 gigapascals, dehydration of deforming samples containing only 5 vol% of antigorite suffices to trigger acoustic emissions, a laboratory-scale analogue of earthquakes...
May 15, 2017: Nature Communications
Uzay Koc-Vural, Ismail Baltacioglu, Pinar Altinci
OBJECTIVES: This study aimed to evaluate the color stability of bulk-fill and nanohybrid resin-based composites polished with 3 different, multistep, aluminum-oxide impregnated finishing and polishing disks. MATERIALS AND METHODS: Disk-shaped specimens (8 mm in diameter and 4 mm in thickness) were light-cured between two glass slabs using one nanohybid bulk-fill (Tetric EvoCeram, Ivoclar Vivadent), one micro-hybrid bulk-fill (Quixfil, Dentsply), and two nanohybrid incremental-fill (Filtek Ultimate, 3M ESPE; Herculite XRV Ultra, Kerr) resin-based composites, and aged by thermocycling (between 5 - 55℃, 3,000 cycles)...
May 2017: Restorative Dentistry & Endodontics
Jingxing Shi, Michael E Pollard, Cesar A Angeles, Ruiqi Chen, J C Gates, M D B Charlton
Coupling between free space components and slab waveguides is a common requirement for integrated optical devices, and is typically achieved by end-fire or grating coupling. Power splitting and distribution requires additional components. Usually grating couplers are used in combination with MMI/Y-splitters to do this task. In this paper, we present a photonic crystal device which performs both tasks simultaneously and is able to couple light at normal incidence and near normal incidence. Our approach is scalable to large channel counts with little impact on device footprint...
May 12, 2017: Scientific Reports
Laura Alvarez, M Paul Lettinga, Eric Grelet
We investigate the dynamic behavior of long guest rodlike particles immersed in liquid crystalline phases formed by shorter host rods, tracking both guest and host particles by fluorescence microscopy. Counterintuitively, we evidence that long rods diffuse faster than short rods forming the one-dimensional ordered smectic-A phase. This results from the larger and noncommensurate size of the guest particles as compared to the wavelength of the energy landscape set by the lamellar stack of liquid slabs. The long guest particles are also shown to be still mobile in the crystalline smectic-B phase, as they generate their own voids in the adjacent layers...
April 28, 2017: Physical Review Letters
Albert Jang, Xiaoping Wu, Edward J Auerbach, Michael Garwood
PURPOSE: To introduce a method of designing single and parallel transmit (pTx) 3D adiabatic π pulses for inverting and refocusing spins that are insensitive to transmit B1 ( B1+) inhomogeneity. THEORY AND METHODS: A 3D adiabatic pulse is created by replacing each piece-wise constant element (or sub-pulse) of an adiabatic full passage (AFP) by a 2D selective pulse. In this study, the parent AFP is an HS1 and each sub-pulse is a 2D pulse derived from a jinc function designed using a spiral k-trajectory...
May 12, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Y Makina, K Mahjoubi, D M Benoit, N-E Jaidane, M Mogren Al-Mogren, M Hochlaf
Ab initio and Perdew, Burke, and Ernzerhof (PBE) density functional theory with dispersion correction (PBE-D3) calculations are performed to study N2-Arn (n ≤ 3) complexes and N2 trapped in Ar matrix (i.e., N2@Ar). For cluster computations, we used both Møller-Plesset (MP2) and PBE-D3 methods. For N2@Ar, we used a periodic-dispersion corrected model for Ar matrix, which consists on a slab of four layers of Ar atoms. We determined the equilibrium structures and binding energies of N2 interacting with these entities...
May 18, 2017: Journal of Physical Chemistry. A
An Ghysels, Richard M Venable, Richard Walter Pastor, Gerhard Hummer
A Bayesian-based methodology is developed to estimate diffusion tensors from molecular dynamics simulations of permeants in anisotropic media, and is applied to oxygen in lipid bilayers. By a separation of variables in the Smoluchowski diffusion equation, the multidimensional diffusion is reduced to coupled one-dimensional diffusion problems that are treated by discretization. The resulting diffusivity profiles characterize the membrane transport dynamics as a function of the position across the membrane, discriminating between diffusion normal and parallel to the membrane...
May 8, 2017: Journal of Chemical Theory and Computation
Frances Morgan, Antony Murphy, William Hendren, Gregory Wurtz, Robert J Pollard
An in situ transmission-based system has been designed to optically monitor the ellipsometry constants of a hyperbolic plasmonic metamaterial during electrochemical growth. The metamaterial, made from an array of vertically aligned gold nanorods, has demonstrated an unprecedented ability to manipulate the polarization of light using subwavelength thickness slabs, making in situ ellipsometric data a powerful tool in the controlled design of such components. In this work, we show practical proof-of-principle of this design method and rationalize the ellipsometric output on the basis of the modal properties of the nanorod metamaterial...
May 10, 2017: ACS Applied Materials & Interfaces
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