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961.
The In DX center and the DX-like configuration of the Cd host atom in CdTe are investigated using density functional theory. The simultaneous calculation of the atomic structure and the electric field gradient (EFG) allows one to correlate the theoretically predicted structure of the DX center with an experimental observable, namely, the EFG obtained from radioactive 111In/111Cd probe atoms in In doped CdTe. In this way, the experimental identification of the DX center structure is established. 相似文献
962.
Davis WB Hess S Naydenova I Haselsberger R Ogrodnik A Newton MD Michel-Beyerle ME 《Journal of the American Chemical Society》2002,124(11):2422-2423
The recent investigation of the apparently anomalous attenuation factor (beta > 1.5 A(-1)) for photoinduced hole injection into DNA duplexes modified by protonated 9-amino-6-chloro-2-methoxyacridine (X+) led to the conclusion that in addition to the electronic couplings, the activation energy must also be distance-dependent. In this communication we report the verification of this postulate by direct measurements of the activation energies for a series of (X+)-modified DNA duplexes which sample an appreciable range of donor-acceptor distances (approximately 4-11 A). The resulting changes in thermal activation energy can be explained within the framework of a distance-dependent reorganization energy. 相似文献
963.
Hann S Zenker A Galanski M Bereuter TL Stingeder G Keppler BK 《Fresenius' Journal of Analytical Chemistry》2001,370(5):581-586
Interaction of cis-[Pt(NH3)2Cl2] (cisplatin) with 5'-guanosine monophosphate (5'-GMP) has been investigated for the first time by on-line coupling of high performance ion chromatography (HPIC) to inductively coupled plasma sector field mass spectrometry (ICP-SFMS). The time-dependent reaction course of the cisplatin-5'-GMP system was followed after incubation under simulated physiological conditions by monitoring the decrease in the concentration of 5'-GMP and the increase in the concentration of formed adducts, on the basis of speciation analysis. Because of the two-step mechanism an intermediate mono adduct was observed together with the major product, the bis adduct cis-[Pt(NH3)2(GMP)2]2-. The data obtained correlated well with those from earlier studies employing orthogonal techniques such as capillary electrophoresis (CE). Furthermore, HPIC-ICP-SFMS provided unambiguous stoichiometric information about the major GMP-adduct. For this purpose the platinum-to-phosphorus ratio was determined by simultaneously measuring 31P and 195Pt. To separate significant interferences from 15N16O+, 14N16O1H+, 12C18O1H+, and 13C17O1H+ on 31P, high-mass resolution (m/deltam = 4,500) proved to be mandatory. The P/Pt signal ratio of 2/1 obtained corresponds to the molar ratio in the bis adduct cis-[Pt(NH3)2(GMP)2]2-. 相似文献
964.
Stephan Kipp Dr. Vladimir Šepelák Dr. habil. Klaus Dieter Becker Prof. Dr. 《Chemie in Unserer Zeit》2005,39(6):384-392
Mechanochemistry offers a wide spectrum of possible applications. The standard preparation methods of solid state chemistry often require high temperatures or pressures, well defined gas atmospheres or special reactants' conditions. In the mechanochemical process not more than an adequately powerful ball mill with accessories is required. With this method, a lot of chemical reactions can be carried out via a non-thermal, sustainable reaction pathway. 相似文献
965.
S. Kalyanasundaram A. Gopalan N. Muniyandi N. G. Renganathan Y. Saito H. Kataoka A. Manuel Stephan R. Nimma Elizabeth 《Ionics》2001,7(1-2):44-52
The lithium salt (x) (x=LiAsF6, LiPF6) was complexed with a blend of poly(vinyl chloride) (PVC) / poly(methyl methacrylate)(PMMA) and plasticized with a combination
of ethylene carbonate(EC) and propylene carbonate(PC). The electrolyte films were prepared using doctor blade method and subjected
to ionic conductivity measurements at nine different temperatures viz.,-30, -15, 0, 15, 30, 40, 50, 60 and 70 °C. The films
were also subjected to TG - DTA and FT-IR analysis. The effect of salt on ionic conductivity is discussed. A 75:25 PMMA/PVC
blend at 60 % plasticizer content has been found to possess optimal properties in terms of ionic conductivity, thermal and
electrochemical stability. 相似文献
966.
967.
We present velocity measurements executed with the new laser-cantilever anemometer (LCA) under various flow conditions. Previously, the basic principles and characteristics of the LCA were investigated. Measurements led to results comparable to common measurement techniques for turbulent flows, such as hot-wire anemometry for air and hot-film anemometry for water [1]. Here we present further experiments where the LCA was used in a snow wind tunnel to investigate the behavior of the cantilever under particle impact. In comparison to data collected with a hot-film anemometer under same conditions, the times series of the LCA showed less pronounced impact characteristics than that of the hot-film, i.e. a recovery time that is shorter and easier to identify. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
968.
Andrew M. McDonagh Marie P. Cifuentes Mark G. Humphrey Stephan Houbrechts Joachim Maes Andr Persoons Marek Samoc Barry Luther-Davies 《Journal of organometallic chemistry》2000,610(1-2)
The preparation of the chloro complex trans-[FeCl2{(R,R)-diph}2] (1) and the alkynyl complexes trans-[M(4-CCC6H4R)Cl{(R,R)-diph}2] [M=Fe, R=NO2 (2); M=Ru, R=H (4), NO2 (5), (E)-CH=CH-4-C6H4NO2 (6); M=Os, R=NO2 (7)], incorporating the optically active diphosphine 1,2-bis(methylphenylphosphino)benzene (diph), are described. Oxidation potentials, as determined by cyclic voltammetry, increase as 2<7<5. Molecular quadratic nonlinearities by hyper-Rayleigh scattering at 1064 nm increase upon introduction of an acceptor group (4<5), chain-lengthening of bridging group (5<6), and proceeding from 3d to 4d and 5d metal (2≤5≤7). Two-level-corrected nonlinearities reproduce the first two trends, but metal variation follows the sequence 2<7<5. The experimental and two-level-corrected nonlinearities for 6 (2795×10−30 and 406×10−30 esu, respectively), are amongst the largest observed thus far for organometallic complexes. Crystals of complexes 2 and 7 exhibit second-harmonic generation (assessed using the Kurtz powder technique), with an efficiency for the former of twice that of urea. 相似文献
969.
An asymptotic analysis is given for the heat equation with mixed boundary conditions rapidly oscillating between Dirichlet
and Neumann type. We try to present a general framework where deterministic homogenization methods can be applied to calculate
the second term in the asymptotic expansion with respect to the small parameter characterizing the oscillations.
Received August 20, 1999 / final version received March 1, 2000?Published online June 21, 2000 相似文献
970.
Summary. We study some additive Schwarz algorithms for the version Galerkin boundary element method applied to some weakly singular and hypersingular integral equations of the first
kind. Both non-overlapping and overlapping methods are considered. We prove that the condition numbers of the additive Schwarz
operators grow at most as independently of h, where p is the degree of the polynomials used in the Galerkin boundary element schemes and h is the mesh size. Thus we show that additive Schwarz methods, which were originally designed for finite element discretisation
of differential equations, are also efficient preconditioners for some boundary integral operators, which are non-local operators.
Received June 15, 1997 / Revised version received July 7, 1998 / Published online February 17, 2000 相似文献