NMR spectra, GIAO and charge density calculations of five-membered aromatic heterocycles

The B3LYP/6-31+G(d) molecular geometry optimized structures of 17 five-membered heterocycles were employed together with the gauge including atomic orbitals (GIAO) density functional theory (DFT) method at the B3LYP/6-31+G(d,p), B3LYP/6-311++G(d,p) and B3LYP/6-311+G(2d,p) levels of theory for the calculation of proton and carbon chemicals shifts and coupling constants. The method of geometry optimization for pyrrole (1), N-methylpyrrole (2) and thiophene (7) using the larger 6-311++G(d,p) basis sets at the B3LYP/6-31+G(d,p), B3LYP/6-311++G(d,p), B3LYP/6-31+G(2d,p) and B3LYP/cc-pVTZ levels of theory gave little difference between calculated and experimental values of coupling constants. In general, the (1)H and 13C chemical shifts for all compounds are in good agreement with theoretical calculations using the smaller 6-31 basis set. The values of nJHH(n=3, 4, 5) and rmnJ(CH)(n=1, 2, 3, 4) were predicted well using the larger 6-31+G(d,p) and 6-311++G(d,p) basis sets and at the B3LYP/6-31+G(d,p), B3LYP/6-311++G(d,p), B3LYP/6-31+G(2d,2p) levels of theory. The computed atomic charges [Mülliken; Natural Bond Orbital Analysis (NBO); Merz-Kollman (MK); CHELP and CHELPG] for the B3LYP/6-311++G(d,p) geometry optimized structures of 1-17 were used to explore correlations with the experimental proton and carbon chemical shifts.     

Nonlinear equations of motion for orthotropic plates

Nonlinear equations of motion for orthotropic plates are proposed on the basis of the three dimensional nonlinear theory of elasticity. The resulting plate model provides a high accuracy, which is confirmed by solving the Vlasov static problem of bending a hinge-supported plate under sinusoidal load.     

Gas-phase clusterization of zinc during magnetron sputtering

The processes of gas-phase clusterization of zinc during dc magnetron sputtering of a zinc target in an argon atmosphere have been investigated. The influence of the working gas pressure and magnetron discharge current on the morphology and structure of the precipitates formed on substrates previously cooled to–50°С is studied. It is shown that dense textured (002)Zn layers with a columnar structure are formed at relatively low argon pressures in the chamber (P = 0.5 Pa) and low discharge currents (100 mA). X-ray amorphous deposits with a fractal coral-like structure arise on substrates at an extremely high argon pressure in the chamber (P = 5 Pa). An increase in the magnetron discharge current at an operating gas pressure of 5 Pa leads to the formation of polycrystalline layers on substrates; the intensity of the XRD peaks related to crystalline zinc increases with an increase in the discharge current. Possible mechanisms of the structural transformation of Zn deposits are considered.     

Ambient Schmittel cyclization promoted by chemoselective triazole-gold catalyst

The Schmittel cyclization was achieved at room temperature through triazole-gold (TA-Au) catalyzed propargyl vinyl ether rearrangement. Other tested [L-Au](+) catalysts gave complex reaction mixtures under identical conditions with no desired products observed. Importantly, because of the employment of mild conditions, sterically hindered groups (such as t-Bu) on allene termini were no longer required, which allowed successful synthesis of previously challenging substrates.     

Synthesis of copolymers of decyl methacrylate with o-allylphenol and their investigation as viscosity improving additives for petroleum oils

Russian Journal of Applied Chemistry - The synthesis of copolymers of decyl methacrylate with o-allylphenol was performed. The influence of various factors on the results of the process was...     

Nonabsolute Integral on Measure Spaces

We define a Henstock-type integral on measure spaces with metrictopologies, and give an example of a function which is integrablebut whose absolute value is not. 1991 Mathematics Subject Classification26A39, 46G12.     

Water-alcohol Separation by Pervaporation through Zeolite Modified Poly(amidesulfonamide)s (PASAs)

A series of poly(amidesulfonamide)s (PASAs) which have been synthesized in our laboratory possess good membrane fabrication properties^[1]. The potential use of these membrane materials in RO, UF and PV were demonstrated^[2,3]. Reminiscent to the PV performance of other glassy polymers, most of these materials exhibit a fairly high separation factor albeit a permeation flux below 35 g m^-2 h^-1 in the PV separation of aqueous alcohol mixtures. To have a real application prospect in PV, the permeation flux through the membranes has to e further improved. The present work represents our effort to upgrade the separation characteristics of PASAs by blending with inert hydrophilic zeolites. Three types of PASAs (structure shown in Figure 1) were selected to be fabricated by blending different amount of zeolite NaA or NaX. The zeolite filled membranes were characterized by SEM, IR spectroscopy, sorption measurements and wide-angle X-ray diffraction. By adding proper amount of NaA into the polymer casting solutions, the resultant zeolite filled membranes exhibited improvement in both selectivity and permeability in the separation of 10% aqueous solutions of ethanol, propan-l-ol and propan-2-ol, as compared to the zeolite free membrane (Table 1).     

The Study of Primary Cosmic Ray Mass Composition Around the

The lg N_e-N_μ relationship has been studied from 4.4×10⁴ events (total observation time is 2.9×10⁶s)collected from Mt. Liang Wang Array (24.5°N, 102.9°E, 2720m above sea level). In order to study the mass composition at the knee, Monte-Carlo simulations for the EAS development and detection under same event selection criteria as used in the experimental data have been performed. The result shows that the mass composition of primary cosmic rays has no obvious change and the dominant component is light nuclei around the knee.