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101.
Iwona Olejniczak Arkadiusz Frąckowiak Jacek Matysiak Augustin Madalan Flavia Pop Narcis Avarvari 《Central European Journal of Physics》2014,12(3):215-220
Infrared and Raman spectra of three chiral molecular conductors (EDT-TTF-OX)2AsF6, comprising of two salts based on enantiopure EDT-TTF-OX donor molecules and one based on their racemic mixture, have been measured as a function of temperature. In the frequency range of the C=C stretching vibrations of EDT-TTF-OX, charge-sensitive modes are identified based on theoretical calculations for neutral and oxidized EDT-TTF-OX using density functional theory (DFT) methods. The positions of C=C stretching modes in both Raman and infrared spectra of the (EDT-TTF-OX)2AsF6 materials are analyzed assuming a linear relationship between the frequency and charge of the molecule. The charge density on the EDTTTF-OX donor molecule is estimated to be +0.5 in all investigated materials and does not change with temperature. Therefore we suggest, that M-I transition observed in (EDT-TTF-OX)2AsF6 chiral molecular conductors at low temperature is not related to the charge ordering mechanism. 相似文献
102.
The translational diffusion constant of a particle, D, in a congested medium or a gel can be written as the product of two terms that account for long-range hydrodynamic interaction between the gel or congested medium and the particle, DEM, and a short-range "steric" term, S. For particles of arbitrary shape, DEM has been examined previously within the framework of the effective medium, EM, model (S. Allison et al., J. Phys. Chem. B 2008, 112, 5858-5866). In the present work, we examine S for rod- and wormlike chain models of duplex DNA in the size range of 100 to over 2000 base pairs. The gel is modeled explicitly as a cubic lattice, and Brownian dynamics simulation is used to examine S for a wide range of rod/wormlike chain and gel parameters. For wormlike chains with P = 50 nm, an empirical formula is derived for S that should be valid over a wide range of wormlike chain/gel parameters. For duplex DNA in the size of several hundred to several thousand base pairs in an agarose gel of 2% or less, fair agreement between modeling and experiment is obtained. However, modeling overestimates the length dependence of D observed experimentally. Finally, the reduction of D of DNA (100 to over 1000 base pairs in length) in cytoplasm relative to water can be accounted for quite well using the effective medium plus steric correction approach. 相似文献
103.
Bankeu JJ Mustafa SA Gojayev AS Lenta BD Tchamo Noungoué D Ngouela SA Asaad K Choudhary MI Prigge S Guliyev AA Nkengfack AE Tsamo E Shaiq Ali M 《Chemical & pharmaceutical bulletin》2010,58(12):1661-1665
Two new sphingolipids mucusamide (1) and mucusoside (2) have been isolated from methanol soluble part of the stem bark of Ficus mucuso WELW., together with fifteen known secondary metabolites including cellobiosylsterol (3), β-sitosterol (4), stigmasterol (5), β-sitosterol 3-O-β-D-glucopyranoside (6), lupeol acetate (7), ursolic acid (8), procatechuic acid (9), 2-methyl-5,7-dihydroxychromone 8-C-β-D-glucoside (10), apigenin (11), (-)-epicatechin (12), (+)-catechin (13), N-benzoyl-L-phenylalanilol (14), α-acetylamino-phenylpropyl α-benzoylamino-phenylpropionate (15), asperphenamate (16) and bejaminamide (17). Structures of compounds 1 and 2 were elucidated by spectroscopic analysis and chemical methods. 相似文献
104.
Pasatoiu TD Etienne M Madalan AM Andruh M Sessoli R 《Dalton transactions (Cambridge, England : 2003)》2010,39(20):4802-4808
A tetranuclear complex and a 1-D coordination polymer with a ladder-like topology have been obtained by connecting [Ni(II)Dy(III)] nodes with dicarboxylato ligands: [Ni?(valpn)?Dy?(III)(pdca)?(NO?)(H?O)?](NO?)·4H?O 1, and (∞)1[Ni?(H?O)?(valpn)?Dy?(tfa)?]·4CH?CN 2 (valpn2? = the dianion of the Schiff base resulting from reacting o-vanillin with 1,3-propanediamine; pdca2? = the dianion of 2,6-pyridinedicarboxylic acid; tfa2? = the dianion of the terephthalic acid). The magnetic measurements show a ferromagnetic interaction between Ni(II) and Dy(III), and that both compounds behave like SMM with strong tunnelling. The barrier of 2 (17.4 K) is higher than that of 1 (13.6 K). 相似文献
105.
M. Augustin R. Iliew C. Etrich D. Schelle H.-J. Fuchs U. Peschel S. Nolte E.-B. Kley F. Lederer A. Tünnermann 《Applied physics. B, Lasers and optics》2005,81(2-3):313-319
We experimentally demonstrate diffractionless guidance and efficient routing of light in two-dimensional photonic crystal slabs at infrared and visible wavelengths. Our particular design allows for simultaneous guidance of TE and TM polarized light beams at the same wavelength. Routing performance and possibilities of propagation loss reduction are investigated experimentally. Experimental results are in excellent agreement with three-dimensional simulations. 相似文献
106.
This article presents an approach to the modeling of CaCO3 fouling and cleaning in a microscale cross-flow heat exchanger. The fouling progress was detected by thermal, fluid dynamical, and optical measures. In general, the observed fouling phenomena at microscale were comparable to those at macroscale. The detected thermal fouling resistance was between 10? 6 and 10? 3 m? 2 K? 1. As expected, crystallization fouling strongly depends on the surface temperature. In addition, the surface coverage can be a useful measure for both processes—fouling and cleaning. An extended approach to derive a reasonable fouling allowance was formulated through a fractional fouling resistance. 相似文献
107.
R. Kalai Selvan C. O. Augustin M. I. Oshtrakh O. B. Milder V. A. Semionkin 《Hyperfine Interactions》2005,165(1-4):231-237
CuFe2O4 nanoparticles and (CuFe2O4)0.95(SnO2)0.05 nanocomposites were studied by XRD, Mössbauer spectroscopy and SQUID magnetometer. The XRD pattern shows the well-defined sharp peaks characterized tetragonal structure of CuFe2O4. The Mössbauer spectrum of CuFe2O4 showed ferrimagnetic structure while spectrum of (CuFe2O4)0.95(SnO2)0.05 composite demonstrated a mixture of ferrimagnetic and paramagnetic components. The D.C. magnetization revealed that SnO2 addition leads to overcoming the “superparamagnetic limit.” 相似文献
108.
Using the Hofer metric, we construct, under a certain condition, a bi-invariant distance on the identity component in the group of strictly contact diffeomorphisms of a compact regular contact manifold. We also show that the Hofer metric on Ham(M) has a right-invariant (but not left invariant) extension to the identity component in the groups of symplectic diffeomorphisms of certain symplectic manifolds.Mathematics Subject classification (2000): 53C12, 53C15. 相似文献
109.
Soil erosion has been considered as the main process related to losses of soil mass and decrease of productivity in cultivated lands as well as on e of the most important processes in landscape evolution. Attention has been paid to many pedological variables affecting intensity of erosion, but little to the influence of iron compounds on the type, size, shape and porosity of soil aggregates. In the present study, three lithopedodomains which were assumed to be closely related to the dominant lithology of the soil parent material, varying in the degree of water erosion intensity, were selected for further analysis which focused mainly on the influence of iron oxide mineralogy on the soil aggregation. Powder X-ray diffractometry, 80 K Mössbauer data and SEM images are used to correlate all these variables with observed erosion activity in the field. The present data indicate that the more the soil is rich in iron (hematite and/or goethite) or aluminium (gibbsite) (hydr)oxide, the smaller are its aggregates and is porous. Soils derived from metabasic rocks are much more susceptible to collapse under wetting than those from other lithologies. They have the highest iron and clay content. Schist-derived soil is richer in muscovite, has bigger aggregates and porous and are less prone to collapse, while the granite-derived soil presents relatively intermediate resistance, when humid. 相似文献
110.
Stefankiewicz AR Harrowfield J Madalan A Rissanen K Sobolev AN Lehn JM 《Dalton transactions (Cambridge, England : 2003)》2011,40(45):12320-12332
An unsymmetrical bis(tridentate) ligand LH in which one binding site can be readily deprotonated forms a kinetically inert [Co(III)L(2)](+) complex which can be used as a "corner" species for the "Coupe du Roi" assembly of trans,trans-[Co(2)M(2)L(4)](6+) metallogrids (M = Fe(II), Co(II), Cu(II), Zn(II)). In the mixed Co(III)/Co(II) species, the oxidation states appear to be localised. In solution, the ligand LH forms octacationic, homometallic [2 × 2] grids with the individual labile metal ions Fe(II), Co(II), Cu(II), Zn(II), seemingly as mixtures of all possible isomers arising from the unsymmetrical nature of the ligand. In the solid state, however, [Zn(4)L(4)](CF(3)SO(3))(8)·4CH(3)CN crystallises as a single species where the cation has S(4) symmetry. This stereoselectivity in the crystalline lattice is associated with interactions between the cation and triflate anions which can again be analysed in terms of the Coupe du Roi concept. 相似文献