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991.
992.
Numerical time evolution of transport states using time dependent Density Matrix Renormalization Group (td‐DMRG) methods has turned out to be a powerful tool to calculate the linear and finite bias conductance of interacting impurity systems coupled to non‐interacting one‐dimensional leads. Several models, including the Interacting Resonant Level Model (IRLM), the Single Impurity Anderson Model (SIAM), as well as models with different multi site structures, have been subject of investigations in this context. In this work we give an overview of the different numerical approaches that have been successfully applied to the problem and go into considerable detail when we comment on the techniques that have been used to obtain the full I–V‐characteristics for the IRLM. Using a model of spinless fermions consisting of an extended interacting nanostructure attached to non‐interacting leads, we explain the method we use to obtain the current–voltage characteristics and discuss the finite size effects that have to be taken into account. We report results for the linear and finite bias conductance through a seven site structure with weak and strong nearest‐neighbor interactions. Comparison with exact diagonalisation results in the non‐interacting limit serve as a verification of the accuracy of our approach. Finally we discuss the possibility of effectively enlarging the finite system by applying damped boundaries and give an estimate of the effective system size and accuracy that can be expected in this case. 相似文献
993.
994.
Dragoslav Šumarac Zoran Petrašković 《Archive of Applied Mechanics (Ingenieur Archiv)》2012,82(10-11):1663-1673
In the present paper, the Preisach model of hysteresis is applied to model cyclic behavior of elasto-plastic material. Rate of loading and viscous effects will not be considered. The problem of axial loading of rectangular cross-section and cyclic bending of rectangular tube (box) will be studied in details. Hysteretic stress–strain loop for prescribed history of stress change is plotted for material modeled by series connection of three unite element. Also moment–curvature hysteretic loop is obtained for a prescribed curvature change of rectangular tube (box). All obtained results clearly show advantages of the Preisach model for describing cyclic behavior of elasto-plastic material. 相似文献
995.
Azra ulovi Franko Bur
ul Vedrana ike uli Mirko Ru
i Petra Brzovi Sabine Montaut Patrick Rollin Ivica Blaevi 《Molecules (Basel, Switzerland)》2021,26(17)
Glucosinolates (GSLs) from Lepidium graminifolium L. were analyzed qualitatively and quantitatively by their desulfo-counterparts using UHPLC-DAD-MS/MS technique and by their volatile breakdown products-isothiocyanates (ITCs) using GC-MS analysis. Thirteen GSLs were identified with arylaliphatic as the major ones in the following order: 3-hydroxybenzyl GSL (glucolepigramin, 7), benzyl GSL (glucotropaeolin, 9), 3,4,5-trimethoxybenzyl GSL (11), 3-methoxybenzyl GSL (glucolimnanthin, 12), 4-hydroxy-3,5-dimethoxybenzyl GSL (3,5-dimethoxysinalbin, 8), 4-hydroxybenzyl GSL (glucosinalbin, 6), 3,4-dimethoxybenzyl GSL (10) and 2-phenylethyl GSL (gluconasturtiin, 13). GSL breakdown products obtained by hydrodistillation (HD) and CH2Cl2 extraction after hydrolysis by myrosinase for 24 h (EXT) as well as benzyl ITC were tested for their cytotoxic activity using MTT assay. Generally, EXT showed noticeable antiproliferative activity against human bladder cancer cell line UM-UC-3 and human glioblastoma cell line LN229, and can be considered as moderately active, while IC50 of benzyl ITC was 12.3 μg/mL, which can be considered as highly active. 相似文献
996.
A heteroleptic titanium metal alkoxide (OPy)2Ti(4MP)2, where OPy = NC5H4(CH2O)-2 and 4MP = OC6H4(SH)-4, was investigated as a candidate precursor for the solution-based (sol-gel) synthesis of titanium oxide via the photoactivation of intermolecular linking reactions (e.g., hydrolysis/condensation). The evolution of the electronic structure of the solution-based molecule arising from conventional (dark) chemical reaction kinetics was compared with that of samples exposed to ultraviolet (UV) radiation at wavelengths of λ = 337.1 nm and 405 nm using UV-visible absorption spectroscopy. Photoinduced changes in the spectra were examined as a function of both the incident wavelength of exposure and the total fluence. Experimental results confirm the UV-induced modification of spectral absorption features, attributed to ligand-localized and charge transfer transitions accompanied by structural changes associated with hydrolysis and condensation. The photoenhancement of reaction kinetics in these processes was confirmed by the increased modification of the absorption features in the solution spectra, which saturated more rapidly under UV-illumination than under dark conditions. Similar saturation behaviors were observed for both the 337.1 nm and the 405 nm incident wavelengths with the same total deposited energy density indicating a relative insensitivity of the photoinduced response to excitation energy for the wavelengths and fluences studied. 相似文献
997.
M. Burianek M. Mühlberg M. Woll M. Schmücker Th. M. Gesing H. Schneider 《Crystal Research and Technology》2009,44(10):1156-1162
Pure and homogeneous single crystals of orthorhombic mullite‐type Bi2M4O9 (M = Al3+, Ga3+, Fe3+), and a mixed Bi2Fe1.7Ga2.3O9 crystal from an equimolar Ga/Fe composition were grown by the top seeded solution growth (TSSG) method. All these compounds melt incongruently in the range of about 800 and 1100 °C. In case of bismuth gallate and ferrate inclusion‐free crystals with dimensions up to several cubic centimeters can be grown. Limited solubility in Bi2O3 and the high steepness of the liquidus curve are the reasons for getting only small imperfect bismuth aluminate crystals. In contrast to ceramic materials preparation reported in literature, divalent calcium and strontium could not be incorporated into the mullite‐type structure during the melt growth process. Several fundamental physical properties like heat capacity, thermal expansion, heat conductivity, elastic constants, high‐pressure behavior and oxygen diffusivity were determined by different research groups using single‐crystalline samples from the as‐grown materials. Furthermore, the refractive indices of Bi2Ga4O9 were measured in the range of 0.430 and 0.700 μm. Such as many other bismuth containing compounds the refractive indices of Bi2Ga4O9 are larger than 2, and Bi2Ga4O9 is an optic biaxial positive crystal. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
998.
Paris E. Georghiou Celine Schneider Grigory Shamov Timothy D. Lash Shofiur Rahman D. Sabrina Giddings 《Supramolecular chemistry》2016,28(5-6):396-402
AbstractSolid-state NMR data are presented to clearly support the formation of a 1:1 supramolecular complex between C60 and the tetra-tert-butylated analogue of calix[4]azulene by a simple mechanochemical hand-grinding of host and guest in a mortar and pestle. The experimental results are supported by a DFT study. 相似文献
999.
1000.
Ian A. Gass Stuart R. Batten Craig M. Forsyth Boujemaa Moubaraki Caspar J. Schneider Keith S. Murray 《Coordination chemistry reviews》2011,255(17-18):2058-2067
The synthesis, structures and magnetism of the complexes [FeII(3-bpp)2][bpmdcK](SeCN)1.7(ClO4)1.3·MeOH·H2O (1), [FeII(3-bpp)2]4[bpmdcH2(H2O)2](ClO4)10·7H2O·3MeOH (2) and cis-[FeII2(NCSe)2((3,5-Me2pz)3CH)2(μ-bpmdc)]·2MeCN (3) (where 3-bpp = 2,6-di(pyrazole-3yl)pyridine, bpmdc = N,N′-bis(4-pyridyl-methyl)diaza-18-crown-6) and (3,5-Me2pz)3CH = tris(3,5-dimethylpyrazole)methane, are presented. These compounds form a study of the supramolecular influence of host–guest/crown-ether interactions and cation-to-crown hydrogen-bonding effects upon d6 spin transitions, the latter occurring above, or near to, room temperature in 1 and 2. Desolvation effects also influence the T1/2 values. The dinuclear compound 3 contains covalent pyridyl (crown) N to Fe bridge bonding and remains high spin. 相似文献