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81.
Levine and Steinhardt's expression is generalised for the structure factor of a binary quasicrystal with AτB composition. The atomic model used in this generalisation is based on the embedding of quasiperiodic chains of A and B atoms such that there is a B atom within every long interval of the A-chain. For the proposed embedding scheme, the range of interpenetration length as well as the ratio of long and short intervals in the two chains are shown to affect the diffracted intensities drastically. The effect of order-disorder on the motif, average quasilattice constant and diffracted intensities is also considered. Conditions for the composite chain to become self-similar, which for the most general embedding is not necessary, are obtained. The application of present decoration scheme to vacancy ordered phases is discussed. 相似文献
82.
A seventh degree rule of the non-product type has been constructed for numerical evaluation of double integrals of an analytic function of two complex variables by choosing a set of 17 points from the set of 25 points needed in the product Birkhoff-Young rule of fifth degree. An asymptotic error estimate for this rule has been determined and the rule has been numerically tested. 相似文献
83.
84.
85.
We use Schwinger’s action principle in quantum mechanics to obtain the quantisation from Lagrangian for the fermionic variables,
as well as when it contains auxiliary coordinates. We illustrate this with a supersymmetric Lagrangian which naturally includes
auxiliary variables. We further show that the action principle also leads to Feynman’s path integral quantisation, which is
aesthetically pleasing. 相似文献
86.
The oxidation of thiohydantoin and rhodanine by quinquivalent vanadium ion is first order with respect to both vanadium ion and the organic substrate. The rate of oxidation increases with increase in concentration of hydrogen ions. The energy, entropy and free energy of activation have been evaluated. Formation of an intermediate complex between the organic substrate and vanadium (V) is not indicated by kinetic evidence. Some possible steps in the reaction have been proposed. 相似文献
87.
Albert E. Ruehli Werner Liniger Pratap Pattnaik 《Numerical Functional Analysis & Optimization》2013,34(3-4):531-545
In this paper, we discuss various A-stable integration methods for stiff ordinary differential equations, suitable for general purpose circuit simulations and device simulation. We point out that some of the popular methods either introduce excessive amounts of numerical damping when applied to a loss-less resonance circuit or fail to sufficiently damp rapidly delaying stiff modes. Furthermore, some of these methods can become unstable when applied with variable steps to stable problems with variable coefficients. Some recently discovered integrators, on the other hand, simultaneously combine the advantages and avoid the disadvantages of the former methods. Furthermore, if implemented properly, these latter methods retain their A-stability when applied with variable steps to the stable variable coefficient test equation. 相似文献
88.
Alekha Kumar Sutar Yasobanta Das asmita Pattnaik Anita Routaray Nibedita Nath Prasanta Rath Tungabidya Maharana 《催化学报》2014,(10)
The novel recyclable free –ONNO– tetradentate Schiff base ligand N,N′‐bis(2‐hydroxy‐3‐ methox‐ybenzaldehyde)4‐methylbenzene‐1,2‐diamine (3‐MOBdMBn) was synthesized. Complexation of this ligand with zinc(3‐MOBdMBn‐Zn) was performed, and the catalytic activity of the complex was evaluated. The polymer‐supported analog of this complex(P‐3‐MOBdMBn‐Zn) was synthesized, and its catalytic activity was studied. These free and polymer‐anchored zinc complexes were prepared by the reactions of metal solutions with one molar equivalent of unsupported 3‐MOBdMBn or P‐3‐MOBdMBn in methanol under nitrogen. The catalytic activity of 3‐MOBdMBn‐Zn and P‐3‐MOBdMBn‐Zn was evaluated in phenol oxidation. The activity of P‐3‐MOBdMBn‐Zn was signif‐icantly affected by the polymer support, and the rate of phenol conversion was around 50% for polystyrene‐supported 3‐MOBdMBn. The experimental results indicated that the reaction rate was affected by the polymer support, and the rate of phenol conversion was 1.64 μmol/(L·s) in the presence of polystyrene‐supported 3‐MOBdMBn. 相似文献
89.
Interfacial polycondensation (IP) is an important technique used in the encapsulation of a variety of active ingredients and synthesis of thin film composite membranes. The present work seeks to advance our understanding of the mechanisms underlying the reaction, phase separation and film formation in this process, and hence, of how the film properties are influenced by preparation conditions. The model presented here incorporates all the essential physicochemical processes at a fundamental level through simple phenomenologies: ionic equilibria in the aqueous phase, resistances due to external mass transfer, diffusion through polymer film, interfacial reaction, thermodynamics of phase separation, and formation of a coherent film. The model has been tested against the data previously communicated [S.J. Wagh, Studies in interfacial polycondensation. Ph.D. Thesis. IIT Bombay, 2004; S.J. Wagh, S.S. Dhumal, A.K. Suresh, An experimental study of polyurea membrane formation by interfacial polycondensation, Journal of Membrane Science, submitted for publication] on polyurea microcapsules. The influence of the model parameters and preparation conditions, on the properties of the polymer and film and their development during reaction, have been studied. The study provides important insights into the process and should help in designing synthesis methodologies to suit the application. 相似文献
90.
A Ajay S Sharma MP Gupt V Bajpai Hamidullah B Kumar MP Kaushik R Konwar RS Ampapathi RP Tripathi 《Organic letters》2012,14(17):4306-4309
A new approach to synthesize a homologous series of 14-, 15-, and 16-membered drug-like, macrocyclic glycoconjugates involving TBAHS promoted azide-propenone intramolecular cycloaddition in designed C-glycopyranosyl butenones from a simple sugar d-glucose and d-mannose is reported. 相似文献