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61.
《Acta Crystallographica. Section C, Structural Chemistry》2018,74(9):991-996
The three binary Tb/Er‐rich transition metal compounds Tb3Pd2 (triterbium dipalladium), Er3Pd2 (trierbium dipalladium) and Er6Co5–x (hexaerbium pentacobalt) crystallize in the space groups Pbam (Pearson symbol oP20), P4/mbm (tP10) and P63/m (hP22), respectively. Single crystals of Tb3Pd2 and Er6Co5–x suitable for X‐ray structure analysis were obtained using rare‐earth halides as a flux. Tb3Pd2 adopts its own structure type, which can be described as a superstructural derivative of the U3Si2 type, which is the type adopted by Er3Pd2. Compound Er6Co5–x belongs to the Ce6Co2–xSi3 family. All three compounds feature fused tricapped {TR6} (R = rare‐earth metal and T = transition metal) trigonal prismatic heterometallic clusters. R3Pd2 is reported to crystallize in the U3Si2 type; however, our more detailed structure analysis reveals that deviations occur with heavier R elements. Similarly, Er6Co5–x was assumed to be stoichiometric Er4Co3 = Er6Co4.5. Our studies reveal that it has a single defective transition‐metal site leading to the composition Er6Co4.72(2). LMTO (linear muffin‐tin orbital)‐based electronic structure calculations suggest the strong domination of heteroatomic bonding in all three structures. 相似文献
62.
P. Sagan G. Wisz B. Tsizh I. Virt I. Rudy 《Molecular Crystals and Liquid Crystals》2018,671(1):148-155
AbstractThe structure, morphology and optical transmittance spectra of pentacene films on the (glass/ITO) surface were studied. The films were grown by two methods - the thermal vacuum deposition (TVD) and pulsed laser deposition (PLD). The electron diffraction pattern from thermally deposited pentacene films confirms their polycrystalline structure while the diffraction pattern of PLD-coated layers has a diffusion character. The results obtained showed that layers deposited by the TVD method has an optical spectrum that is characteristic for the pentacene film in contrary to the layers deposited by the PLD method. It is found a sensitivity of the optical transmittance of pentacene films to the ammonia action, which may be used for development the optical gas sensor. 相似文献
63.
AbstractIn this study, the photovoltaic organic-inorganic structures were created by deposition of poly(3,4-ethylenedioxythiophene) film doped by poly(styrenesulfonate) and reduced graphene oxide on the porous silicon/silicon substrate. Formation of the hybrid structure was confirmed by means of atomic-force microscopy and Fourier transform infrared spectroscopy. The current-voltage characteristics of the obtained structures were studied. It was found the increase of electrical conductivity and photo-induced signal in organic-inorganic structures. Temporal parameters and spectral characteristics of photoresponse in the 400–1100?nm wavelength range were investigated. The widening of spectral photosensitivity in a short-wavelength range due to light absorption in various layers of the multijunction structure in comparison with single crystal silicon was revealed. 相似文献
64.
《Mathematical Methods in the Applied Sciences》2018,41(14):5691-5710
We consider a 2 time scale nonlinear system of ordinary differential equations. The small parameter of the system is the ratio ϵ of the time scales. We search for an approximation involving only the slow time unknowns and valid uniformly for all times at order O(ϵ2). A classical approach to study these problems is Tikhonov's singular perturbation theorem. We develop an approach leading to a higher order approximation using the renormalization group (RG) method. We apply it in 2 steps. In the first step, we show that the RG method allows for approximation of the fast time variables by their RG expansion taken at the slow time unknowns. Next, we study the slow time equations, where the fast time unknowns are replaced by their RG expansion. This allows to rigorously show the second order uniform error estimate. Our result is a higher order extension of Hoppensteadt's work on the Tikhonov singular perturbation theorem for infinite times. The proposed procedure is suitable for problems from applications, and it is computationally less demanding than the classical Vasil'eva‐O'Malley expansion. We apply the developed method to a mathematical model of stem cell dynamics. 相似文献
65.
A cost‐effective curvature calculation approach for interfacial flows on unstructured meshes 下载免费PDF全文
We present a simple and cost‐effective curvature calculation approach for simulations of interfacial flows on structured and unstructured grids. The interface is defined using volume fractions, and the interface curvature is obtained as a function of the gradients of volume fractions. The gradient computation is based on a recently proposed gradient recovery method that mimicks the least squares approach without the need to solve a system of equations and is quite easy to implement on arbitrary polygonal meshes. The resulting interface curvature is used in a continuum surface force formulation within the framework of a well‐balanced finite‐volume algorithm to simulate multiphase flows dominated by surface tension. We show that the proposed curvature calculation is at least as accurate as some of the existing approaches on unstructured meshes while being straightforward to implement on any mesh topology. Numerical investigations also show that spurious currents in stationary problems that are dependent on the curvature calculation methodology are also acceptably low using the proposed approach. Studies on capillary waves and rising bubbles in viscous flows lend credence to the ability of the proposed method as an inexpensive, robust, and reasonably accurate approach for curvature calculation and numerical simulation of multiphase flows. 相似文献
66.
《Wave Motion》2018
Large cable net structures have been widely applied in aerospace engineering due to the feature of light-weight, high packaging efficiency, and high thermal stability. Structural vibrations induced by a variety of disturbances are inevitable in the space environment, resulting in the requirement of effective vibration control strategies for large cable net structures. Since the large cable net structures have many closely spaced vibrational modes in the range of low frequencies, traditional modal based control may cause modal truncation and spillover problems. In this paper, a wave-based boundary control strategy is adopted and its effectiveness to control the vibration of cable net structures is investigated, by transfer function analysis and numerical methods. It is found that the structural vibration can be absolutely resisted by applying the wave-based boundary controllers onto all the exterior nodes, when disturbances come from the external boundaries of the cable net. Our results in this paper can provide a theoretical basis for the vibration control of large cable net structures. 相似文献
67.
68.
In this paper we study the domain of the generator of stable processes, stable-like processes and more general pseudo- and integro-differential operators which naturally arise both in analysis and as infinitesimal generators of Lévy- and Lévy-type (Feller) processes. In particular we obtain conditions on the symbol of the operator ensuring that certain (variable order) Hölder and Hölder–Zygmund spaces are in the domain. We use tools from probability theory to investigate the small-time asymptotics of the generalized moments of a Lévy or Lévy-type process , for functions f which are not necessarily bounded or differentiable. The pointwise limit exists for fixed if f satisfies a Hölder condition at x. Moreover, we give sufficient conditions which ensure that the limit exists uniformly in the space of continuous functions vanishing at infinity. As an application we prove that the domain of the generator of contains certain Hölder spaces of variable order. Our results apply, in particular, to stable-like processes, relativistic stable-like processes, solutions of Lévy-driven SDEs and Lévy processes. 相似文献
69.
Extremely Photostable Electron-Deficient Phthalocyanines that Generate High Levels of Singlet Oxygen
Prof. Dr. Taniyuki Furuyama Yusuke Miyaji Kazuya Maeda Prof. Dr. Hajime Maeda Prof. Dr. Masahito Segi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(7):1678-1682
A robust lead-mediated synthetic procedure for the generation of phthalocyanines substituted with electron-withdrawing groups has been developed. The free-base phthalocyanine and various metal complexes were prepared without discernible degradation of the peripheral electron-withdrawing substituents. Upon irradiation with red light, some of the thus-obtained metal complexes generated high levels of singlet oxygen. In particular, a palladium complex exhibited attractive photostability upon exposure to singlet oxygen as a bleaching agent. The photostability of such complexes that may manifest concomitantly to the generation of high levels of singlet oxygen was attributed to the presence of the electron-withdrawing groups, which results in energetically low-lying highest occupied molecular orbitals. 相似文献
70.
Theo Steininger Jait Dixit Philipp Frank Maksim Greiner Sebastian Hutschenreuter Jakob Knollmüller Reimar Leike Natalia Porqueres Daniel Pumpe Martin Reinecke Matev raml Csongor Varady Torsten Enßlin 《Annalen der Physik》2019,531(3)
NIFTy , “Numerical Information Field Theory,” is a software framework designed to ease the development and implementation of field inference algorithms. Field equations are formulated independently of the underlying spatial geometry allowing the user to focus on the algorithmic design. Under the hood, NIFTy ensures that the discretization of the implemented equations is consistent. This enables the user to prototype an algorithm rapidly in 1D and then apply it to high‐dimensional real‐world problems. This paper introduces NIFTy 3, a major upgrade to the original NIFTy framework. NIFTy 3 allows the user to run inference algorithms on massively parallel high performance computing clusters without changing the implementation of the field equations. It supports n‐dimensional Cartesian spaces, spherical spaces, power spaces, and product spaces as well as transforms to their harmonic counterparts. Furthermore, NIFTy 3 is able to handle non‐scalar fields, such as vector or tensor fields. The functionality and performance of the software package is demonstrated with example code, which implements a mock inference inspired by a real‐world algorithm from the realm of information field theory. NIFTy 3 is open‐source software available under the GNU General Public License v3 (GPL‐3) at https://gitlab.mpcdf.mpg.de/ift/NIFTy/tree/NIFTy_3 . 相似文献