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31.
Hanan Luss 《The Journal of the Operational Research Society》1983,34(11):1099-1105
In previous work, Erickson and Luss examined the problem of optimally sizing computer records so as to minimize wasted space. They assumed that a fixed number of record sizes can be used to store messages of various lengths. If a message cannot be stored in any single record, it is stored in multiple records of the same size. However, the record size used to accommodate divided messages is not used to store any message that fits into any of the other record sizes. Here, we relax the latter constraint and allow the record size designated to store divided messages to store also other messages. A dynamic programming algorithm that finds the optimal record sizes is presented. However, since the computational effort needed to find the optimal record sizes is large, we also derive bounds for the optimal solution and give a heuristic algorithm that provides near optimal solutions. 相似文献
32.
Polson MI Loiseau F Campagna S Hanan GS 《Chemical communications (Cambridge, England)》2006,(12):1301-1303
The dinuclear ruthenium complex of a large, planar bis-tridentate bridging ligand has been prepared; to the best of our knowledge, this species is the near IR-emitting Ru(II) complex exhibiting the longest-lived emission and highest quantum yield reported so far, due to the dramatic reduction in its radiationless decay rate constant. 相似文献
33.
Five types of haemocytes are observed in the fourth larval instar of the black cutworm, Agrotis ipsilon: prohaemocytes (PRs), plasmatocytes (PLs), granulocytes (GRs), spherule cells (SPs) and adipohaemocytes (ADs). Infection of A. ipsilon fourth larval instar with Bacillus thuringiensis and dimilin resulted in a reduction of the total haemocyte count. Changes in the differential haemocyte population during bacterial and dimilin infections have been assessed. The PRs % decreased significantly while SPs, PLs, and GRs % increased significantly after the application of the two insecticides at 12 and 24 h. Ultrastructural alternations and malformations have been observed in circulating haemocytes of A. ipsilon larvae treated with dimilin and B. thuringiensis. 相似文献
34.
A new method was developed using AFM images of a fiber surface to regenerate the surface roughness in 3D geometry, such as the cylindrical shape of a “model” fiber. The Langevin equation was used to derive the fluctuations of a carbon fiber surface image. The equation contains two quantities, D(1) (h) and D(2) (h) which in physics represent drift and diffusion coefficients. Knowing this coefficient and adding a proper noise function, a similar surface of larger dimension with the same statistical properties of the initial data was created. The generated surface was mapped into cylindrical coordinates, then a mesh generated. The resulting reconstructed surface, input over the geometry of a cylindrical shape, can be implemented for finite element analysis of a single fiber surrounded by matrix and generalized to a many fiber model. 相似文献
35.
This paper applied the modified variational iteration method to the nonlinear coupled partial differential equations via the
generalized nonlinear Hirota Satsuma coupled KdV equations, the nonlinear coupled Kortewge–de Vries KdV equations and the
nonlinear shallow water equations together with the initial conditions. The proposed modification is made by introducing Adomian’s
polynomials in the correct functional. The suggested algorithm is quite efficient and is practically well suited for use in
such problems. The proposed iterative scheme finds the solution without any discritization, liberalization, perturbation,
or restrictive assumptions. 相似文献
36.
Abstract: Mass spectrometry (MS) has become an integral tool in life sciences. The first step in MS analysis is ion formation (ionization). Many ionization methods currently exist; electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI) are the most commonly used. ESI relies on the formation of charged droplets releasing ions from the surface (ion evaporation model) or via complete solvent evaporation (charge residual model). MALDI ionization, however, is facilitated via laser energy and the use of a matrix. Despite wide use, ESI cannot efficiently ionize nonpolar compounds. Atmospheric pressure chemical ionization (APCI) and atmospheric pressure photo ionization (APPI) are better suited for such tasks. APPI requires photon energy and a dopant, whereas APCI is similar to chemical ionization. In 2004, ambient MS was introduced in which ionization occurs at the sample in its native form. Desorption electrospray ionization (DESI) and direct analysis in real time (DART) are the most widely used methods. In this mini-review, we provide an overview of the main ionization methods and the mechanisms of ion formation. This article is educational and intended for students/researchers who are not very familiar with MS and would like to learn the basics; it is not for MS experts. 相似文献
37.
38.
A number of 3-substituted-2-(substituted-phenoxymethyl) quinazolin-4(3H)-one derivatives 4a,b, 5a-c, 6, 7a-f, 8a-e and 9a,b have been synthesized. Their structures have been elucidated on the basis of elemental analyses and spectroscopic studies (IR, 1H-NMR, MS). A preliminary evaluation of the anticonvulsant activity of the prepared compounds has indicated that compounds 4b, 7b-f, 8a and 9b exhibit significant anticonvulsant activity, while compounds 6, 8b and 8d show mild to moderate activity. 相似文献
39.
Hanan Al‐Awadi Maher R. Ibrahim Nouria A. Al‐Awadi Yehia A. Ibrahim 《Journal of heterocyclic chemistry》2008,45(3):723-727
40.
Felix Unglaube Hanan Atia Stephan Bartling Carsten R. Kreyenschulte Esteban Mejía 《Helvetica chimica acta》2023,106(2):e202200167
The synthesis of primary alcohols (from olefins) is an important and challenging transformation, as most of the current methods suffer from regioselectivity issues. This work describes the utilization of rice husk (RH) from agricultural waste as support for the preparation of a catalyst for the conversion of olefin oxides to primary alcohols. The catalyst was synthesized by pyrolysis of RH impregnated with nickel, and characterized by IR, AAS, XRD, BET, XPS, TEM, and TPD technics. The catalyst shows excellent activity and selectivity towards anti-Markovnikov alcohols, acting simultaneously as Brønsted acid, solid Lewis acid, and as hydrogenation catalyst. A substrate screening was done, the catalyst's recycling stability was assessed, and a plausibly reaction mechanism was proposed. 相似文献