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391.
The action of toluene-p-sulphonic acid on tri- and tetracyclic benzocyclobutenols leads to the corresponding olefins. In some cases, after rearrangement derivatives of anti-2,7- benzobicyclo[3,2,1]octene are obtained. A mechanism is proposed for this rearrangement. 相似文献
392.
André N Jensen TB Scopelliti R Imbert D Elhabiri M Hopfgartner G Piguet C Bünzli JC 《Inorganic chemistry》2004,43(2):515-529
Three unsymmetrical ditopic hexadentate ligands coded for the recognition of trivalent lanthanide ions have been synthesized, L(AB), L(AC), and L(BC), where A represents a benzimidazole-pyridine-benzimidazole coordination unit, B a benzimidazole-pyridine-carboxamide one, and C a benzimidazole-pyridine-carboxylic acid moiety. Under stoichiometric 2:3 (Ln:L) conditions, these ligands self-assemble with lanthanide ions to yield triple-stranded bimetallic helicates having a sizable stability in acetonitrile: log beta(23) values for Eu are equal to 23.9 +/- 0.5 (L(AB)), 23.3 +/- 0.7 (deprotonated L(AC)), and 29.8 +/- 0.5 (deprotonated L(BC)). The crystal structure of the EuEu helicate with L(AB) shows 9-coordinate metal ions and an HHH (H stands for head) configuration of the helically wrapped ligand strands. In the presence of equimolar quantities of Ln and Ln' ions, L(AB) displays a remarkable predisposition to form HHH-heterobimetallic edifices, as proved both in the solid state by the crystal structures of the LaEu, LaTb, PrEr, and PrLu helicates and in solution by NMR spectroscopy. In all cases, the benzimidazole-pyridine-carboxamide units of the three ligands are bound to the smaller lanthanide ion, a fact further ascertained by high-resolution luminescence data on LaEu and by (1)H NMR. Analysis of the lanthanide-induced (1)H NMR shifts and of the spin-lattice relaxation times of the [LnLu(L(AB))(3)](6+) series (Ln = Ce, Pr, Nd, Sm, Eu) demonstrates the isostructural nature of the complexes in solution and that the crystal structure of LaTb is a good model for the solution structure. The selectivity of L(AB) for heteropairs of Ln(III) ions increases with increasing difference in ionic radius, resulting in 70% of the heterobimetallic species for deltar(i) = 0.1 A and up to 90% for LaLu (deltar(i) = 0.18 A), and corresponding to delta(deltaG) in the range 3-10 kJ.mol(-)(1). The origins of this stabilization are discussed in terms of the donor properties of the coordinating units and of the preferential formation of HHH isomers. 相似文献
393.
We consider the problem of minimizing the makespan on a batch processing machine, in which jobs are not all compatible. Only
compatible jobs can be included into the same batch. This relation of compatibility is represented by a split graph. All jobs
are available at the same date. The capacity of the batch processing machine is finite or infinite. The processing time of
a batch is given by the processing time of the longest job in the batch. We establish the NP-hardness of the general problem
and present polynomial algorithms for several special cases. 相似文献
394.
C.?DeffayetEmail author J.?Mourad 《International Journal of Theoretical Physics》2005,44(10):1743-1752
We review how one can construct a deconstructed gravity by a transverse latticification of 5D General Relativity. The obtained theory is a multigravity theory, with link fields that are explicitly constructed out of the metric. We also discuss the spectrum of the theory at the level of the linearized
theory. 相似文献
395.
Mourad E.H Ismail 《Journal of Mathematical Analysis and Applications》1985,108(2):575-594
A single serving queueing model is studied where potential customers are discouraged at the rate λn = λqn, 0 < q < 1, n is the queue length. The serving rate is μn = μ(1 ? qn), n = 0, 1,…. The spectral function is computed and the corresponding set of orthogonal polynomials is studied in detail. The slightly more general model with and the analogous orthogonal polynomials are also investigated. In both cases a method developed by Pollaczek is used which has been used very successfully to study new sets of orthogonal polynomials by Askey and Ismail. 相似文献
396.
Mourad E.H Ismail Thanaa M.T Rashed 《Journal of Mathematical Analysis and Applications》1977,57(3):724-731
We study expansions in polynomials {Pn(x)}∞o generated by ∑∞n = oPn(x)tn = A(t) φ(xtkθ(t)), θ(0) ≠ 0, and ∑∞n = 0Pn(x)tn = ∑kj = 1Aj(t) φ(xt?j), ?1,…,?k being the k roots of unity. The case k = 1 is contained in a recent work by Fields and Ismail. We also prove a new generalization of Vandermond's inverse relations. 相似文献
397.
Mourad Hidouri Besma Lajmi Ahmed Driss Mongi Ben Amara 《Journal of chemical crystallography》2004,34(10):669-672
A new monophosphate Na1.28Ni0.86Fe2(PO4)3 has been synthesized by a flux method and structurally characterized by single-crystal X-ray diffraction. The compound crystallizes in the orthorhombic space group Ibmm with the parameters: a = 6.438(2) Å, b = 10.515(3) Å, c = 13.166(3) Å, Z = 4. The structure is built up from Fe2O10 units of edge-sharing FeO6 octahedra, which are connected through the corners of MO6 (M = Ni2+ or a vacancy) octahedra and PO4 tetrahedra to form a three-dimensional framework analogous to that of -CrPO4. Of the two crystallographically distinct Na+ sites contained in this structure, one is totally filled whereas the other is 28% occupied. 相似文献
398.
Mourad E. H. Ismail Mizan Rahman Dennis Stanton 《Proceedings of the American Mathematical Society》1999,127(10):2931-2941
We establish expansion formulas of -exponential functions in terms of continuous -ultraspherical polynomials, continuous -Hermite polynomials and Askey-Wilson polynomials. The proofs are based on solving connection coefficient problems.
399.
Khaled G. Abdel-Wahhab Eitedal M. Daoud Aliaa El Gendy Hagar H. Mourad Fathia A. Mannaa Maha M. Saber 《Applied biochemistry and biotechnology》2018,186(1):161-173
Diabetic neuropathy (DN) is the highly occurred complication of diabetes mellitus; it has been defined as an event of peripheral nerve dysfunction characterized by pain, allodynia, hyperalgesia, and paraesthesia. The current study was conducted to evaluate the efficacy of low-level laser therapy (LLLT) in the management of neuropathy in diabetic rats. The used animals were divided into the following groups: negative control, streptozotocin-induced diabetic rats, and diabetic rats with peripheral neuropathy (DNP) and DNP treated with gabapentin or with LLLT. Behavioral tests were carried out through hotplate test for the determination of pain sensations and the Morris water maze test for spatial reference memory evaluation. Blood samples were collected at the end of treatment for biochemical determinations. In the current study, the latency of hind-paw lick decreased significantly when DNP are treated with gabapentin or LLLT. The Morris water maze test showed that LLLT treatment improved memory that deteriorated in DNP more than gabapentin do. The results of the biochemical study revealed that LLLT could not affect the level of beta-endorphin that decreased in DNP but significantly decreased S100B that rose in DNP. PGE2 and cytokines IL-1β, IL-10, and TNF-α showed significant increase in DNP compared with control group. The gabapentin administration or LLLT application significantly reversed the levels of the mentioned markers towards the normal values of the controls. Levels of serum MDA and nitric oxide increased significantly in the DNP but rGSH showed significant decrease. These markers were improved significantly when the DNP were treated with gabapentin or LLLT. The treatment with gabapentin or LLLT significantly decreased the raised level in total cholesterol in DNP but could not decrease the elevated level of triglycerides, while LDL cholesterol decreased significantly in DNP treated with gabapentin but not affected by LLLT. Values of serum alanine aminotransferase (ALAT), aspartate aminotransferase (ASAT), urea, and creatinine increased significantly in the DPN and diabetic rats without peripheral neuropathy (PN) compared with control group. The treatment of DNP with gabapentin induced significant increases in ALAT and ASAT activities but LLLT treatment induced significant decreases in ALAT and ASAT activities as compared with DNP group. Neither gabapentin nor LLLT could improve the elevated levels of serum urea and creatinine in the DNP. It could be concluded that LLLT is more safe and effective than gabapentin in the management of neuropathy in diabetic rats. 相似文献
400.
Rania Charrad Dr. Hanna E. Solt Dr. József Valyon László Trif Dr. Faouzi Ayari Dr. Mourad Mhamdi Jenő Hancsók Dr. Ferenc Lónyi 《ChemistryOpen》2020,9(11):1123-1134
Co/SSZ-13 zeolites were prepared by heating the finely dispersed mixture of NH4-SSZ-13 and different cobalt salts up to 550 °C. Investigations by thermogravimetry – differential scanning calorimetry – mass spectrometry provided new insight into details of the solid-state reaction. Formation of Co carrying hydrate melt or volatile species was shown to proceed from chloride, nitrate, or acetylacetonate Co precursor salts upon thermal treatment. This phase change allows the transport of the Co species into the zeolite pores. The reaction of the NH4+ or H+ zeolite cations and the mobile Co precursors generates vapor or gas products, readily leaving the zeolite pores, and cobalt ions in lattice positions suggesting that solid-state ion-exchange is the prevailing process. The obtained catalysts are of good activity and N2 selectivity in the CH4/NO-SCR reaction. The thermal treatment of acetate or formate salts give solid intermediates that are unable to get in contact and react with the cations in the zeolite micropores. These catalysts contain mainly Co-oxide clusters located on the outer surface of the zeolite crystallites and have poor catalytic performance. 相似文献