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61.
The Pummerer intermediate generated from 10 with TFAA was trapped intermolecularly in the presence of Lewis acid by the indoline 2 at position 5. Sequential treatment of the resulted compound 3 with Ra-Ni, LiAlH4 and active MnO2 gave compound 6 in high overall yield. 相似文献
62.
Alejandro R. Diaz Noboru Klkuchl Panos Papalambros John E. Taylor 《基于设计的结构力学与机械力学》2013,41(2):215-230
ABSTRACT Finite element solutions of improved quality are obtained by optimizing the location of nodes of the finite element grid, while keeping the number of degrees of freedom fixed. The formulation of the grid optimization problem is based on the reduction of error associated with interpolation of the exact solution, using functions from the finite element space. Element sizes are selected as design variables: length in R1 and area in R2. Analytically derived optimality conditions are presented and an approximation to these conditions is introduced to obtain a set of operationally useful equations that can be used as guidelines for construction of improved grids. Example problems are given for illustration. 相似文献
63.
Let Φ be a finite root system of rank n and let m be a nonnegative integer. The generalized cluster complex Δm(Φ) was introduced by S. Fomin and N. Reading. It was conjectured by these authors that Δm(Φ) is shellable and by V. Reiner that it is (m + 1)-Cohen-Macaulay, in the sense of Baclawski. These statements are proved in this paper. Analogous statements are shown
to hold for the positive part Δ+m(Φ) of Δm(Φ). An explicit homotopy equivalence is given between Δ+m(Φ) and the poset of generalized noncrossing partitions, associated to the pair (Φ, m) by D. Armstrong. 相似文献
64.
M. E. Grypeos G. A. Lalazissis S. E. Massen C. P. Panos 《Zeitschrift für Physik A Hadrons and Nuclei》1989,332(4):391-395
The relative contribution of the recoilless and quasifreeΛ-production in the (K?,π?) strangeness exchange reaction in nuclei is estimated by using the nuclear Debye-Waller factor. The expressions for theΛ-oscillator spacing ?ωΛ needed for such an estimate are derived by means of procedures which lead to quite simple formulae for ?ωΛ as function of the mass number and are useful in obtaining improved results. 相似文献
65.
Christos Lampropoulos Theocharis C. Stamatatos Khalil A. Abboud George Christou 《Polyhedron》2009,28(9-10):1958-1964
The use of a convenient source of MnIII ions, namely the [Mn(OR)(O2CR′)2]n (R = H, Me, and R′ = Me, But) family of 1-D coordination polymers, afforded two new enneanuclear and decanuclear molecular clusters, homometallic [Mn9O7(O2CBut)13(MeCN)2] (3) and heterometallic [Mn10?xFex(OMe)20(O2CMe)10] (x < 10) (4), respectively. Compound 3 was synthesized by a solvent-induced structural transformation, whereas complex 4 resulted from the reaction of [Mn(OH)(O2CMe)2]n with an FeIII source. The core of 3 comprises two [Mn4O2]8+ butterfly units and a [Mn3O]7+ triangular unit fused together by sharing one Mn atom. Magnetic susceptibility measurements of 3 revealed dominant antiferromagnetic interactions within the molecule, and a ground state of S = 1 with many low-lying excited states. Complex 4 is a mixed FeIII/MnIII single-strand molecular wheel, which forms 3D nanotubular stacks arranged in a zig–zag fashion. The described work suggests that the [Mn(OR)(O2CR′)2]n compounds represent excellent starting materials for MnIII carboxylate cluster chemistry. 相似文献
66.
Christos Kokkinos Anastasios Economou Ioannis Raptis Thanasis Speliotis 《Electrochemistry communications》2009,11(2):250-253
This work describes a novel type of antimony electrode for adsorptive stripping voltammetry (AdSV). The electrode was microfabricated by coating a silicon chip with a thin antimony-film by means of sputtering and the active area of the electrode was defined by photolithography. The resulting antimony-film electrodes (SbFEs) were characterized by optical and electrochemical techniques. The sensors were tested for the detection of low concentrations of Ni(II) by AdSV in the presence of dimethylglyoxime. Well-formed stripping peaks and a linear dependence of the stripping peak current on the Ni(II) concentration were observed on the microfabricated SbFEs while comparative measurements attempted with electroplated SbFEs were unsuccessful. Utilizing thin-film technology for the formation of the antimony-film extends the scope of these devices as mercury-free sensors in AdSV. 相似文献
67.
Per-Olof Fjällström Jyrki Katajainen Christos Levcopoulos Ola Petersson 《BIT Numerical Mathematics》1990,30(3):378-384
We present a parallel algorithm for finding the convex hull of a sorted set of points in the plane. Our algorithm runs inO(logn/log logn) time usingO(n log logn/logn) processors in theCommon crcw pram computational model, which is shown to be time and cost optimal. The algorithm is based onn
1/3 divide-and-conquer and uses a simple pointer-based data structure.Part of this work was done when the last three authors were at the Department of Computer and Information Science, Linköping University. The research of the second author was supported by the Academy of Finland. 相似文献
68.
Christos M. Tsoumanis 《Talanta》2010,82(2):575-358
A field flow approach for the in situ monitoring of wastewater quality is developed and assessed in this work, based on a combination of methods employing deconvolution of molecular absorption spectra and in situ/on-line analysis of wastewater effluent of various origin. The approach involves in situ immersion probes to monitor basic physicochemical parameters followed by UV spectrum deconvolution in order to provide a rapid estimate of organic matter, suspended solids and nitrate and on-line analysis of phosphates in a fully automated setup. The collected data are then treated with a series of supervised pattern recognition techniques in order to classify wastewater effluent according to their origin in three major categories namely municipal, industrial and hospital. The results suggest that the method affords a good approximation of realistic concentrations, as determined by reference methods, while it affords a good classification among various wastewater effluents of different origin. In that manner, the method enables a rapid inference of treated wastewater quality and a robust assessment of treatment process state, especially with regards to violations of effluent quality parameters. 相似文献
69.
Ilias Papasarantos Persefoni Klimentzou Vassiliki Koutrafouri Maria Anagnostouli Christos Zikos Maria Paravatou-Petsotas Evangelia Livaniou 《Applied biochemistry and biotechnology》2010,162(1):221-232
A biotin derivative, namely biotin–aminocaproic acid–lysine (BAL), was synthesized with solid-phase chemistry, conjugated
to a carrier-protein, and used for rabbit immunization. The aminocaproic acid–lysine “long-arm” was used in order to project
the biotin-hapten above the carrier-protein surface. Lysine was selected due to its Nε-amino group, through which BAL was conjugated to the carrier-protein. BAL was synthesized on a commercially available resin
with the Fmoc-solid-phase strategy; this has simplified the experimental procedure, overcome the need for intermediate purification
steps, and led to a final product of high purity, with high yield. The anti-BAL antibodies recognized free biotin, as shown
with an in-house-developed ELISA, in which biotin conjugated to a synthetic “lysine–dendrimer” was used to coat the ELISA
microwells. In immunocytology and Western-blot experiments, the anti-BAL antibodies led to similar results with those obtained
with streptavidin. Synthetic derivatives of hapten molecules that can be easily prepared with solid-phase chemistry, such
as BAL, may be used for the development of specific antibodies for the corresponding hapten. 相似文献
70.
Kefalidis CE Baudoin O Clot E 《Dalton transactions (Cambridge, England : 2003)》2010,39(43):10528-10535
DFT(B3PW91) calculations of the mechanism of the intramolecular C(sp(3))-H arylation of 2-bromo-tert-butylbenzene to form benzocyclobutene catalysed by Pd(PR(3)) (R = Me, (t)Bu) and a base (acetate, bicarbonate, carbonate) show that the preferred mechanism is highly dependent on the nature of the phosphine and the base used in the calculations. With the experimental reagents (P(t)Bu(3) and carbonate) the rate-determining step is C-H activation with the base coordinated trans to the C-H bond. An agostic interaction of a geminal C-H bond with respect to the bond to be cleaved induces a lowering of the activation barrier. 相似文献