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101.
Of the four published osmium fluorine compounds in the oxidation state +7, OsO3F, OsO2F3, OsOF5, and OsF7, only one (OsOF5) is a real Os(VII) compound. OsO(3)F has obviously been OsO4. OsO2F3 in its two modifications is a mixed-valence Os(VI)/Os(VIII) compound, whereas a new compound Os2O3F7 is a mixed-valence OsV/Os(VIII) compound. The molecular structures of OsO3F, OsO2F3, and OsO3F2 are calculated. OsO3F2 seems to exist in two forms, with D3h and Cs symmetry. The original preparation of OsF7 could not be reproduced, only OsF6 has been obtained. 相似文献
102.
In this paper, we establish exact solutions for five complex nonlinear Schrödinger equations. The semi-inverse variational principle (SVP) is used to construct exact soliton solutions of five complex nonlinear Schrödinger equations. Many new families of exact soliton solutions of five complex nonlinear Schrödinger equations are successfully obtained. 相似文献
103.
M. T. Darvishi S. Ahmadian S. Baloch Arbabi M. Najafi 《Optical and Quantum Electronics》2018,50(1):32
In this paper, the sine–cosine method is employed to construct exact solutions of the space-time fractional (\(1+1\))-dimensional nonlinear Schrödinger models. Many new families of exact traveling wave solutions of these models are successfully obtained. It is shown that the proposed method provides a more powerful mathematical tool for solving nonlinear space-time fractional evolution equations in mathematical physics. 相似文献
104.
105.
Elham Y Hashem Magda S Saleh 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2002,58(2):239-247
The electronic absorption spectra of some substituted pyridinols in organic solvents of different polarities are studied. Also, the solvent effects on the intramolecular charge transfer bands are discussed using various solvent parameters. The acid-base equilibria of the compounds used are studied spectrophotometrically in various mixed aqueous solvents at 25 degrees C and 0.1 M ionic strength (NaClO4). Furthermore, the influence of the solvents on the dissociation constants and tautomeric equilibria of a pyridinol derivatives are discussed. The effect of molecular structure of the pyridinols on the pK's is also examined. 相似文献
106.
This paper considers the stability and eigenvalue analyses for a bladed rotor which goes under cylindrical and conical whirling. The model consists of a group of flexible blades which are modeled by beams and rigid disk on the elastic bearings. The model is a Hamiltonian system which is perturbed by small dissipative forces. Krein’s theorem reveals that the forward whirling mode and the blade collective motion may cause instability when their frequencies cut themselves in the Campbell diagram. An unstable interaction between the blades and the conical whirling is discovered. The eigenmode and eigenvalue evolutions are determined on the stability boundary. The bifurcation analysis is performed by applying multiple scales method around the stability boundary. It is shown that the damping distribution between the blades and the bearings may shift the unstable mode. 相似文献
107.
The modal interaction which leads to Hamiltonian Hopf bifurcation is studied for a nonlinear rotating bladed-disk system. The model, which is discussed in the paper, is a Jeffcott rotor carrying a number of planar blades which bend in the plane of the motion. The rigid rotating disk is supported on nonlinear bearings. It is supposed that this dynamical system is a Hamiltonian system which is perturbed by small dissipative and nonlinear forces. Krein’s theorem is employed for obtaining a stability criterion. The nonlinear eigenvalue equations on the stability boundary are turned into ordinary differential equations (ODEs) by differentiating them over the rotating speed. By solving these ODEs, the eigenmodes and the eigenvalues on the stability boundary are obtained. The bifurcation analysis is performed by applying multiple scales method around the boundary. The rotor nonlinear behavior and damping effects are studied for different conditions on the rotating speed and nonlinearity type by the bifurcation equation. It is shown that the damping distribution between the blades and bearings may shift the unstable mode. Depending on the nonlinearity type, subcritical and supercritical Hopf bifurcation are possible. 相似文献
108.
Aliasghar Jarrahpour Edris Ebrahimi Reza Khalifeh Hashem Sharghi Mohammad Sahraei Véronique Sinou Christine Latour Jean Michel Brunel 《Tetrahedron》2012,68(24):4740-4744
A novel series of β-lactams bearing an anthraquinone moiety have been synthesized from imines derived from anthraquinone-2-carbaldehyde and ketenes by a [2+2] cycloaddition reaction. The cycloadducts were fully characterized and evaluated for their antimalarial activities against Plasmodium falciparum K14 resistant strain and showed moderate to excellent EC50 values varying from 9 to 50 μM. 相似文献
109.
S. Masoud Nabavizadeh Hashem Amini Fatemeh Jame Sedigheh Khosraviolya Hamid R. Shahsavari Fatemeh Niroomand Hosseini Mehdi Rashidi 《Journal of organometallic chemistry》2012
New cyclometalated platinum(II) complexes [PtMe(C^N)L], 1, in which C^N = deprotonated 2-phenylpyridine (ppy), benzo[h]quinoline (bhq) or 2-(p-tolyl)pyridine (tpy) and L = PPh3 or PMePh2, were synthesized by the reaction of [PtMe(C^N)(SMe2)] with 1 equiv of L. The reaction of complexes 1 with MeI gave the cyclometalated Pt(IV) complexes [PtMe2I(C^N)L], 3. On the basis of kinetic studies, using Uv–visible spectroscopy, it was suggested that the latter oxidative addition reactions were proceeded by an SN2 mechanism. The rates of the reactions at different temperatures were measured and consistent with the proposed mechanism, large negative ΔS3 values were found for each reaction. Besides, rate of reactions (in CHCl3) involving the PPh3 complexes [PtMe(C^N)(PPh3)], were almost 3–5 times slower than those involving the PMePh2 complexes [PtMe(C^N)(PMePh2)]. This was attributed to the electronic and steric effects of PPh3 ligand as compared with that of PMePh2 ligand which was further confirmed using density functional theory (DFT) calculations through finding approximate structures for the described complexes. 相似文献
110.
Jean Fotie Jessica L. Rhodus Hashem A. Taha Carolyn S. Reid 《Heteroatom Chemistry》2012,23(6):598-604
Two C,N‐linked dimeric 1,2‐dihydro‐2,2,4‐trimethylquinolines, namely 6‐chloro‐1‐(6‐chloro‐1,2‐dihydro‐2,2,4‐trimethylquinolin‐8‐yl)‐1,2‐dihydro‐2,2,4‐trimethylquinoline ( 3a ) and 6‐ethoxy‐1‐(6‐ethoxy‐1,2‐dihydro‐2,2,4‐trimethylquinolin‐8‐yl)‐1,2‐dihydro‐2,2,4‐trimethylquinoline ( 3b ), have been prepared through a silver‐catalyzed dimerization of their corresponding monomers. The effect of different silver salts on the reaction was also investigated, and the obtained results suggest that silver ions effectively catalyzed the formation of a C–N bond under these mild conditions. This represents one of the rare reports on the silver‐catalyzed C–N bond formation through a coupling of a secondary amine and an activated aromatic system, via a direct C–H functionalization. Theoretical studies showed that these dimeric structures favor a conformation in which their monomer units are oriented approximately perpendicular to each other, with an intramolecular hydrogen bond (N–H distance of 2.33 Å) forming between the hydrogen atom of the amine in one of the monomeric units and the tertiary nitrogen atom of the other one. 相似文献