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91.
Ebrahim Ghanbari-Adivi 《Brazilian Journal of Physics》2012,42(3-4):172-179
The differential and total cross sections for electron capture by positrons from helium atoms are calculated using a first-order distorted wave theory satisfying the Coulomb boundary conditions. In this formalism, a parametric potential is used to describe the electron screening in a consistent and realistic manner. The present procedure is self-consistent because (a) it satisfies the correct boundary conditions and post–prior symmetry, and (b) the potential and the electron binding energies appearing in the transition amplitude are consistent with the wave functions describing the collision system. The results are compared with the other theories and with the available experimental measurements. At the considered range of collision energies, the results agree reasonably well with recent experiments and theories. 相似文献
92.
Ebrahim Karkhaneei Mohammad Hasan Zebrajadian Mojtaba Shamsipur 《Journal of inclusion phenomena and macrocyclic chemistry》2001,40(4):309-312
7Li NMR measurements were employed to monitor the stoichiometry andstability of Li+ ion complexes with 12-crown-4 (12C4), 15-crown-5 (15C5), benzo-15-crown-5 (B15C5) l8-crown-6 (18C6), dicyclohexano-18-crown-6 (DC18C6) and dibenzo-18-crown-6 (DB18C6) in binary acetone-nitrobenzene mixtures of varying composition. In all cases studied, the variation of 7Li chemical shift with the crown/Li+ mole ratio indicated the formation of 1:1 complexes. The formation constants of the resulting complexes were evaluated from computer fitting of the mole ratio data to an equation that relates the observed chemical shifts to the formation constant. In all solvent mixtures used, the stabilities of the resulting 1:1 complexes varied in the order15C5 > B15C5 > DC18C6 > 18C6 > 12C4 >DB18C6. It was found that,in the case of all complexes, an increase in the percentage of acetone in thesolvent mixtures significantly decreased the stability of the complexes. 相似文献
93.
Hyperfine Interactions - Cement clinker is the main component of Portland cement. It is composed of four main phases. One of them is the brownmillerite or the ferrite phase of cement clinker. It is... 相似文献
94.
Mandana Samari Kermani Ned Djilali Saeed Jafari Ebrahim Jahanshahi Javaran 《Journal of Dispersion Science and Technology》2018,39(6):777-791
The dynamics and rheology of particles in a Newtonian fluid subjected to shear are simulated using Lattice Boltzmann Method. A computationally-efficient Smoothed Profile Method is used to resolve fluid-solid interactions, and the Lennard-Jones inter-particle potential is implemented to account for inter-particle forces. The use of a bi-periodic computational domain with Lees-Edward boundary conditions allows simulation for systems consisting of a large number of particles under shear. The method is validated for single and dual particle problems and an analysis is performed for multi-particle problems under a range of shear rates and particle fractions. The introduction of particle-particle interactions, which are physically important in many engineering processes, is found to have a considerable impact on the dynamics, agglomeration and rheology. The total stress exhibits high unsteadiness primarily due to the solid component contribution, at higher particle fractions. The simulations underscore the complex interplay between shear, interparticle forces and agglomeration and the complex dependencies of the rheological properties. 相似文献
95.
Mohyeddin Safarzaei Malek Taher Maghsoodlou Ebrahim Mollashahi Nourallah Hazeri Mojtaba Lashkari 《Research on Chemical Intermediates》2018,44(12):7449-7458
A one-pot three-component condensation reaction of 3-amino-5-methylisoxazole, aryl aldehyde and 2-naphthol to afford the corresponding 3-amino isoxazolmethylnaphthols in good to excellent yields. The remarkable features of this new procedure are high conversions, clean reaction condition, short reaction time, nonhazardous and environmentally friendly reaction condition, inexpensive and easily commercially availability of the catalyst and simple work-up procedures. 相似文献
96.
Saeidian Hamid Sadighian Hamed Arabgari Masomeh Mirjafary Zohreh Ayati Seyed Ebrahim Najafi Ezzatollah Moghaddam Firouz Matloubi 《Research on Chemical Intermediates》2018,44(1):601-612
Research on Chemical Intermediates - We report robust green synthesis of novel 1,2,3-triazole-based sulfonamides bearing different motifs such as fluorine under click conditions in presence of a... 相似文献
97.
Ferhat Can Özkaya Weaam Ebrahim Maximilian Klopotowski Zhen Liu 《Natural product research》2018,32(7):840-843
The anti-neuroinflammatory meroterpenoid citreohybridonol was isolated for the first time from a sponge-derived fungus Penicillium atrovenetum. In this study, in addition to isolation and structure featuring, its unambiguous absolute configuration was determined exclusively by single crystal X-ray diffraction. The C-17-keto tautomer was clearly observed in X-ray analysis. The substance crystallises in the monoclinic space group P21 with a = 10.7496(5) Å, b = 14.3286(7) Å, c = 17.4909(8) Å, β = 103.235(2)°, V = 2622.5(2) Å3, Z = 2, Dcalcd = 1.280 g/cm3. The chirality of the asymmetric carbon atoms was as follows: C3 (S), C5 (R), C6 (S), C8 (S), C9 (R), C10 (R), C13 (R), C14 (R). 相似文献
98.
A highly selective and sensitive anodic stripping differential pulse polarographic method has been developed for the determination of trace amount of bismuth in various samples after adsorption of its 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complex on amberlite XAD-2 resin in the pH range of 2.0-3.0. The retained analyte on the resin recovered with 10.0 ml of 2 M hydrochloric acid and bismuth is determined by anodic stripping differential pulse polarography. In this case, 0.15 μg of bismuth can be concentrated in the column from 1100 ml of aqueous sample, where its concentration is as low as 0.14 ng ml−1 and the linearity is maintained in the concentration range 0.05-160 μg ml−1 in final solution with a correlation coefficient of 0.999 and relative standard deviation of ±1.2%. Various parameters such as the effect of pH, flow rate, and interference of number of metal ions on the determination of bismuth have been studied in detail to optimize the conditions for determination of bismuth in standard alloys: Nippon Keikinzoku Kogyo (NKK CRM No. 916 aluminum alloy); (NKK CRM No. 1021 Al, Si, Cu, Zn alloy); and (NKK CRM No. 920 aluminum alloy), biological samples: National Institute for Environmental Studies (NIES, No. 5 human hair; NIES, No. 7 tea leaves) and water samples: (spring water, river water; Kerman water; and Shiraz water). 相似文献
99.
An efficient one-pot synthesis of tetrahydrobenzo[b]pyran is described. This involved the three-component reaction of aromatic aldehydes, molononitrile, and dimedone in the presence of a catalytic amount of Caro's acid supported on silica gel in ethanol/water under reflux. 相似文献
100.