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81.
Marsella MJ Yoon K Estassi S Tham FS Borchardt DB Bui BH Schreiner PR 《The Journal of organic chemistry》2005,70(5):1881-1884
Photochemical cyclization of compound 1, a homoenediyne (-CCC=CCH2CC-) bearing two ethynylanthracene chromophores, yields two isomeric dihydrocyclopent[a]indene ring systems, spiro-fused to the 9-position of a 9,10-dihydroanthracene moiety. Evidence of a photochemically initiated diradical cyclization pathway is proposed on the basis of (i) hydrogen abstraction from reaction with 1,4-cyclohexadiene (1,4-CHD) and (ii) the observation of 1,4-addition of benzene (solvent). The reaction was further analyzed by a complete density functional theory (DFT) study, using an unrestricted approach (UBLYP) with a 6-31G* basis set for the open-shell triplet states of the reactants, products, and diradical intermediates to model the photochemical nature of observed transformation. A mechanism detailing the observed cyclization/addition reaction is proposed. 相似文献
82.
Muhammad Aslam Mirza Abdul Jabbar Kandhro Muhammad Yar Khuhawar Rafee Arain 《Journal of separation science》2009,32(18):3169-3177
An analytical procedure has been developed for the separation of Cu(II), Ni(II), Co(II), Fe(II), Pd(II), Th(IV), V(IV), and determination of Fe(II), Co(II), Ni(II), and V(IV) by MEKC after chelation with bis(salicylaldehyde)tetramethylethylenediimine (H2SA2Ten). Uncoated fused silica capillary was used with an applied voltage of 30 kV with photo‐diode array detection at 228 nm. SDS was added as micellar medium at pH 8.2 with sodium tetraborate buffer (0.1 M). Linear calibrations were established within 0.015–1000 μg/mL of each element with LOD within 5–67 ng/mL. The method was applied for the determination of vanadium from crude oil and ore samples in the range 0.34–2.40 and 114.2–720.7 μg/g with RSD 1.7–3.8 and 0.98–2.30% (n = 3), respectively. Fe, Ni, and Co present in crude oil and ore samples were also determined with RSD 1.3–2.8, 1.1–4.1, and 1.2–3.5% (n = 3), respectively. The results were compared with that of supplier's specifications and atomic absorption spectrometry (AAS). Method was evaluated by standard addition technique. 相似文献
83.
Douglas N. Hales V. Sridharan Abirami Radhakrishnan Satya S. Chakravorty Samia M. Siha 《European Journal of Operational Research》2008
Although Information Technology (IT) solutions improve the collection and validation of operational data, Operations Managers must often rely on self-reported data from workers to make decisions. The problem with this data is that they are subject to intentional manipulation, thus reducing their suitability for decision-making. A method of identifying manipulated data, digital analysis, addresses this problem at low cost. In this paper, we demonstrate how one uses this method in real-world companies to validate self-reported data from line workers. The results of our study suggest that digital analysis estimates the accuracy of employee reported data in operations management, within limited contexts. These findings lead to improved operating performance by providing a tool for practitioners to exclude inaccurate information. 相似文献
84.
Muhammad Aslam Noor Muhammad Waseem Khalida Inayat Noor Eisa Al-Said 《Optimization Letters》2013,7(5):991-1007
In this paper, we use the variational iteration technique to suggest and analyze some new iterative methods for solving a system of nonlinear equations. We prove that the new method has fourth-order convergence. Several numerical examples are given to illustrate the efficiency and performance of the new iterative methods. Our results can be viewed as a refinement and improvement of the previously known results. 相似文献
85.
Muhammad Aslam Noor 《Journal of Applied Mathematics and Computing》2000,7(3):581-599
In recent years, the theory of Wiener-Hopf equations has emerged as a novel and innovative technique for developing efficient and powerful numerical methods for solving variational inequalities and complementarity problems. In this paper, we provide an account of some of the fundamental aspects of the Wiener-Hopf equations with major emphasis on the formulation, computational algorithms, various generalizations and their applications. We also suggest some open problems for further research with sufficient information and references. 相似文献
86.
In this paper, using the penalty method in conjunction with graph-convergence, we study the existence of solutions for a class of generalized variational inequalities with variational problem constraints. Our results extend, improve and develop some known results in this field. Our method of proofs is very simple and does not use the hemicontinuity nor the pseudo-continuity properties of monotone operators. 相似文献
87.
M. Ali Paracha Ishtiaq Ahmed M. Jamil Aslam 《The European Physical Journal C - Particles and Fields》2007,52(4):967-973
We study long-distance effects in the rare exclusive semileptonic decays B→K1ℓ+ℓ-, where K1 is the axial vector meson. The form factors describing the meson transition amplitudes of the effective Hamiltonian are calculated
using the Ward identities, which are then used to calculate the branching ratio and the forward–backward asymmetry in these
decay modes. The zero of the forward–backward asymmetry is of special interest and provides us with a precision test of the
standard model. 相似文献
88.
89.
Tin oxide (SnO2) thin films (about 200 nm thick) have been deposited by electron beam evaporation followed by annealing in air at 350-550 °C for two hours. Optical, electrical and structural properties were studied as a function of annealing temperature. The as-deposited film is amorphous, while all other annealed films are crystalline (having tetragonal structure). XRD suggest that the films are composed of nanoparticles of 5-10 nm. Raman analysis and optical measurements suggest quantum confinement effects that are enhanced with annealing temperature. For instance, Raman peaks of the as-deposited films are blue-shifted as compared to those for bulk SnO2. Blue shift becomes more pronounced with annealing temperature. Optical band gap energy of amorphous SnO2 film is 3.61 eV, which increases to about 4.22 eV after crystallization. Two orders of magnitude decrease in resistivity is observed after annealing at 350-400 °C due to structural ordering and crystallization. The resistivity, however, increases slightly with annealing temperature above 400 °C, possibly due to improvement in stoichiometry and associated decrease in charge carrier density. 相似文献
90.
Muhammad Aslam Noor 《Journal of Applied Mathematics and Computing》2000,7(2):363-371
In this paper, we use the auxiliary principle technique to suggest and analyze a class of predictor-corrector methods for solving noncoercive mixed variational inequalities. The convergence of the proposed method requires only the partially relaxed strongly monotonicity, which is even weaker than the co-coercivity. As special cases, we obtain a number of new and known results for classical variational inequalities. 相似文献