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821.
Azadeh Farahzadi Maryam Beigmohamadi Stephan Kremers Michael Heuken 《Applied Surface Science》2010,256(22):6612-14284
The optical properties of tris(8-hydroxyquinoline) aluminum (Alq3), N,N′-diphenyl-N,N′-bis(1-naphthyl)-1-1′biphenyl-4,4″diamine (α-NPD) and other amorphous organic materials for OLEDs application, e.g. 4,4-bis(2,2-diphenyl vinyl)-1,1-biphenyl (DPVBI) and Spiro-DPVBI have been studied by multi-angle spectroscopic ellipsometry (SE). The thin films of these materials have been deposited by organic vapor phase deposition (OVPD). The structural characterization has been performed using atomic force microscopy (AFM) and X-ray reflectometry (XRR). Comparison of the measurements using these different independent techniques enables the precise determination of the optical model for dielectric function of these thin films. The detail analyses on Alq3 and α-NPD show that the Kim model with Gaussian broadening provides a significantly better fit to the ellipsometry data than the frequently used harmonic oscillator model. This conclusion is further proved by performing similar measurements on other amorphous organic samples for OLEDs application, e.g. DPVBI and Spiro-DPVBI. This result can be explained by the characteristic features of electronic states in organic molecules. 相似文献
822.
Olga A. Efremova Yuri V. Mironov Hans-Jürgen Pietzsch Holger Stephan Christiane Perrin Vladimir E. Fedorov 《Journal of Cluster Science》2009,20(1):77-81
Abstract A new cubane-type cluster complex Re4Te4Cl4(C4H4N3)4 · 2DMF has been synthesized by reaction of Re4Te4Cl8(TeCl2)4 with 2-aminopyrazine C4H5N3 in DMF. The crystal structure of compound has been solved by X-ray single crystal diffraction method. Crystal data for Re4Te4Cl4(C4N3H4)4 · 2DMF: a = 22.8718(16) ?, b = 8.5936(7) ?, c = 20.5720(17) ?, β
o = 106.493(2), V = 3877.1(5) ?3, R
1 = 0.0466, R
w(F
2) = 0.1191. In the complex bidentate aminopyrazine ligands are coordinated in two different types, namely, two of four aminopyrazine
ligands bind to a single rhenium atom, and each of two other ligands is coordinated as bridge between two rhenium atoms.
Graphical Abstract A new cubane-type cluster complex Re4Te4Cl4(C4H4N3)4 · 2DMF with two coordination modes of bidentate aminopyrazine ligands has been synthesized and structurally characterized.
相似文献
823.
Akihiko Yoshikawa Stephan B. H. Bach Grant N. Merrill 《Journal of the American Society for Mass Spectrometry》2009,20(6):1015-1029
Dichloro(ethylenediamine)platinum(II), Pt(en)Cl2, was dissolved in H2O and D2O, and the resulting aqueous solutions were electrosprayed into a quadrupole ion-trap mass spectrometer. A series of major
and minor ionic hydrolysis products were detected. These ions were then subjected to collision-induced dissociation. As an
aid in interpreting the experimental results, density functional theory calculations were carried out. These computations
permitted the structures and energetics associated with the hydrolysis products to be determined. An understanding of the
hydrolysis of PtenCl2 and related coordination complexes is essential in the rational design of metal-based drugs. 相似文献
824.
The relation between the non-adiabatic vibrational correction to the reduced mass, i.e. the vibrational g-factor, and the electric dipole moment gradient of a diatomic molecule is investigated. An explicit expression for the “irreducible” non-adiabatic contribution in terms of excited electronic states is derived. The importance of this expression for the analysis of vibration-rotational spectra of diatomic molecules is discussed and explicit expressions are presented for the first two fitting parameters in an expansion of the non-adiabatic vibrational term in an effective vibration-rotational Hamiltonian. Results of ab initio multiconfigurational self consistent field calculations of the non-adiabatic contribution to vibrational g-factor of hydrides and fluorides of Li, B, Al, Ga and monoxides of C, Si and Ge are presented and compared with the corresponding non-adiabatic contributions to the rotational g-factor. 相似文献
825.
826.
Sobottka SB Geiger KD Salzer R Schackert G Krafft C 《Analytical and bioanalytical chemistry》2009,393(1):187-195
Infrared spectroscopic imaging is a promising intraoperative tool which enables rapid, on-site diagnosis of brain tumors during
neurosurgery. A classification model was recently developed using infrared spectroscopic images from thin tissue sections
to grade malignant gliomas, the most frequent class of primary brain tumor. In this study the model was applied to 54 specimens
from six patients with inhomogeneous gliomas composed of regions with different tumor density and morphology. The resection
was controlled using neuronavigation which transfers the findings obtained by preoperative magnetic resonance imaging (MRI)
into the operating field. For comparison, all specimens were independently evaluated by histopathology after hematoxylin and
eosin staining. The infrared-derived grading agreed with histopathology and MRI findings for almost all specimens. With regard
to histopathological assessment, sensitivities of 100% (22/22) and 93.1% (27/29) and specificities of 96.9% (31/32) and 88.0%
(22/25) were achieved, depending on whether the classification was based on the predominant or maximal tumor grade, respectively,
in the specimen. Altogether, in 98% (53/54) of all specimens the decision to continue or not continue tumor resection could
have been made according to the infrared spectroscopic classification. This retrospective study clearly demonstrates that
infrared spectroscopic imaging may help to define tumor margins intraoperatively and to detect high-grade tumor residues for
achieving more radical tumor resection.
MRT-guided tumor resection (left) is combined with infrared spectroscopy-based tissue classification (middle, right). With regard to histopathological assessment, sensitivities of 100% and 93.1% and specificities of 96.9% and 88.0% were
achieved for 54 specimens. (TIF 47.1 KB) 相似文献
827.
Stephan Brandt 《Discrete Mathematics》2009,309(12):3786-237
As an edge variant of the well-known irregularity strength of a graph G=(V,E) we investigate edge irregular total labellings, i.e. functions f:V∪E→{1,2,…,k} such that f(u)+f(uv)+f(v)≠f(u′)+f(u′v′)+f(v′) for every pair of different edges uv,u′v′∈E. The smallest possible k is the total edge irregularity strength of G. Confirming a conjecture by Ivan?o and Jendrol’ for a large class of graphs we prove that the natural lower bound is tight for every graph of order n, size m and maximum degree Δ with m>111000Δ. This also implies that the probability that a random graph from G(n,p(n)) satisfies the Ivan?o-Jendrol’ Conjecture tends to 1 as n→∞ for all functions p∈[0,1]N. Furthermore, we prove that is an upper bound for every graph G of order n and size m≥3 whose edges are not all incident to a single vertex. 相似文献
828.
Stephan Dominique Andres 《Discrete Applied Mathematics》2009,157(9):1980-1987
We introduce the incidence game chromatic number which unifies the ideas of game chromatic number and incidence coloring number of an undirected graph. For k-degenerate graphs with maximum degree Δ, the upper bound 2Δ+4k−2 for the incidence game chromatic number is given. If Δ≥5k, we improve this bound to the value 2Δ+3k−1. We also determine the exact incidence game chromatic number of cycles, stars and sufficiently large wheels and obtain the lower bound for the incidence game chromatic number of graphs of maximum degree Δ. 相似文献
829.
Stephan Pannier Kathrin Grossenbacher Martin Liebscher Wolfgang Graf Michael Kaliske 《PAMM》2011,11(1):731-732
In many engineering applications, a structural design is determined by way of a multi-stage design process. Thereby, the information of previous simulations, e.g. sensitivity analysis, should be used for further investigations. In special, the aim is to improve the reliability as early as possible. Therefore, an approach is presented to determine alternative permissible design spaces on the basis of arbitrary point sets. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
830.
One of the challenges in the numerics of free surface flows is the coupling of the flow field to the geometry of the domain. The most simple approach is an explicit decoupling, i.e. computing the flow field with geometrical information of a prior time step and then updating the geometry. This widely used approach leads to a severe CFL condition of the type , which may prescribe infinitesimally small time step sizes in the interesting case of a small Weber number (i.e. high surface tension). A semi-implicit approach utilizing the fact that , where xk is a parametrization of the capillary boundary Γ, is also available [1]. This approach can be proven to be unconditionally stable but is of first order only. It also suffers from relatively strong numerical dissipation. We present a fully implicit approach using a backward differentiation formula to achieve a time discretization method that is of second order and only minimally dissipative. A numerical example of an oscillating drop showing very low numerical dissipation and second order convergence as well as numerical evidence for the stability of the method is presented. Since the method requires the solution of a highly nonlinear coupled system, possible preconditioners for this system are discussed, including a lower order decoupling. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献