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1.

Padavattan Govindaswamy Patrick J. Carroll Yurij A. Mozharivskyj Mohan Rao Kollipara 《Journal of Chemical Sciences》2006,118(4):319-326

The reaction of [{(η

^{5}-C_{5}Me_{5})M(μ-Cl)Cl}_{2}] {where M = Rh (1), Ir (**2**)} with functionalized phosphine viz., diphenyl-2-pyridylphosphine (PPh_{2}Py) in dichloromethane solvent yield neutral ϰ^{1}-P-coordinated rhodium and iridium complexes [(η^{5}-C_{5}Me_{5})RhCl_{2}(κ^{1}-P-PPh_{2}Py)]**3**and [(η^{5}-C_{5}Me_{5}) IrCl_{2}(ϰ^{1}-P-PPh_{2}Py)]**4**. Reaction of complexes 1 and 2 with the ligand PPh_{2}Py in methanol under reflux give bis-substituted complexes such as [(η^{5}-C_{5}Me_{5})RhCl(ϰ^{1}-P-PPh_{2}Py)_{2}]^{+}**5**and [(η^{5}-C_{5}Me_{5})IrCl(ϰ^{1}-P-PPh_{2}Py)_{2}]^{+}**6**, whereas stirring in methanol at room temperature gives P-, N-chelating complexes of the type [(η^{5}-C_{5}Me_{5})RhCl(ϰ^{2}-P-N-PPh_{2}Py)]^{+}7 and [(η^{5}-C_{5}Me_{5})IrCl(ϰ^{2}-P-N-PPh_{2}Py)]^{+}**8**. Neutral ϰ^{1}-P-coordinated complexes [(η^{5}-C_{5}Me_{5})RhCl_{2}(ϰ^{1}-P-PPh_{2}Py)]**3**and [(η^{5}-C_{5}Me_{5})IrCl_{2}(ϰ^{1}-P-PPh_{2}Py)]**4**easily undergo conversion to the cationic P-, N-chelating complexes [(η^{5}-C_{5}Me_{5})RhCl(ϰ^{2}-P-N-PPh_{2}Py)]^{+}**7**and [(η^{5}-C_{5}Me_{5}) IrCl(ϰ^{2}-P, N-PPh_{2}Py)]^{+}**8**on stirring in methanol at room temperature. These complexes are characterized by FT-IR and FT-NMR spectroscopy as well as analytical methods. The molecular structures of the representative complexes [(η^{5}-C_{5}Me_{5})RhCl_{2}(ϰ^{1}-P-PPh_{2}Py)]**3**, [(η^{5}-C_{5}Me_{5})IrCl_{2}(ϰ^{1}-P-PPh_{2}Py)]**4**and hexafluorophosphate salt of complex [(η^{5}-C_{5}Me_{5})IrCl(ϰ^{2}-P-PPh_{2}Py)_{2}]^{+}**6**are established by single-crystal X-ray diffraction methods 相似文献2.

This paper deals mainly with generalizations of results in finitary combinatorics to infinite ordinals. It is well-known that for finite ordinals ∑

_{bT<αβ}is the number of 2-element subsets of an α-element set. It is shown here that for any well-ordered set of arbitrary infinite order type α, ∑_{bT<αβ}is the ordinal of the set*M*of 2-element subsets, where*M*is ordered in some natural way. The result is then extended to evaluating the ordinal of the set of all*n*-element subsets for each natural number*n*≥ 2. Moreover, series ∑_{β<α}f(β) are investigated and evaluated, where α is a limit ordinal and the function*f*belongs to a certain class of functions containing polynomials with natural number coefficients. The tools developed for this result can be extended to cover all infinite α, but the case of finite α appears to be quite problematic. 相似文献3.

P.A. Ramachandran 《Numerical Methods for Partial Differential Equations》2006,22(4):831-846

Time‐dependent differential equations can be solved using the concept of method of lines (MOL) together with the boundary element (BE) representation for the spatial linear part of the equation. The BE method alleviates the need for spatial discretization and casts the problem in an integral format. Hence errors associated with the numerical approximation of the spatial derivatives are totally eliminated. An element level local cubic approximation is used for the variable at each time step to facilitate the time marching and the nonlinear terms are represented in a semi‐implicit manner by a local linearization at each time step. The accuracy of the method has been illustrated on a number of test problems of engineering significance. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2006 相似文献

4.

This paper solves the problem of the duration of the total eclipseof a satellite of a body, provided that (a) the body is sphericalin shape and the mass distribution inside the body is sphericallysymmetrical; (b) the satellite is a very small object; (c) thesatellite's orbit around a body is circular and the satellitecan pass through the centre of its shadow; (d) a source of lightis the source of the conical body's shadow (umbra) and it doesnot change its apparent position in the sky; (e) there are noperturbations on the satellite's orbit. The solution presentedrepresents the general discussion of the problem based on utilizationof some parts of the theory of contraction mappings. 相似文献

5.

A simple scheme is developed for treatment of vertical bed topography in shallow water flows. The effect of the vertical step on flows is modelled with the shallow water equations including local energy loss terms. The bed elevation is denoted with

*z*_{b}^{‐}for the left and*z*_{b}^{+}for the right values at each grid point, hence exactly representing a discontinuity in the bed topography. The surface gradient method (SGM) is generalized to reconstruct water depths at cell interfaces involving a vertical step so that the fluxes at the cell interfaces can accurately be calculated with a Riemann solver. The scheme is verified by predicting a surge crossing a step, a tidal flow over a step and dam‐break flows on wet/dry beds. The results have shown good agreements compared with analytical solutions and available experimental data. The scheme is efficient, robust, and may be used for practical flow calculations. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献6.

In this work, the natural convection in a concentric annulus between a cold outer square cylinder and a heated inner circular cylinder is simulated using the differential quadrature (DQ) method. The vorticity‐stream function formulation is used as the governing equation, and the coordinate transformation technique is introduced in the DQ computation. It is shown in this paper that the outer square boundary can be approximated by a super elliptic function. As a result, the coordinate transformation from the physical domain to the computational domain is set up by an analytical expression, and all the geometrical parameters can be computed exactly. Numerical results for Rayleigh numbers range from 104 to 106 and aspect ratios between 1.67 and 5.0 are presented, which are in a good agreement with available data in the literature. It is found that both the aspect ratio and the Rayleigh number are critical to the patterns of flow and thermal fields. The present study suggests that a critical aspect ratio may exist at high Rayleigh number to distinguish the flow and thermal patterns. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献

7.

LYNDA D. RODWELL EDWARD B. BARBIER CALLUM M. ROBERTS TIM R. McCLANAHAN 《Natural Resource Modeling》2002,15(4):453-486

ABSTRACT. The excessive and unsustainable exploitation of our marine resources has led to the promotion of marine reserves as a fisheries management tool. Marine reserves, areas in which fishing is restricted or prohibited, can offer opportunities for the recovery of exploited stock and fishery enhancement. In this paper we examine the contribution of fully protected tropical marine reserves to fishery enhancement by modeling marine reserve‐fishery linkages. The consequences of reserve establishment on the long‐run equilibrium fish biomass and fishery catch levels are evaluated. In contrast to earlier models this study highlights the roles of both adult (and juvenile) fish migration and larval dispersal between the reserve and fishing grounds by employing a spawner‐recruit model. Uniform larval dispersal, uniform larval retention and complete larval retention combined with zero, moderate and high fish migration scenarios are analyzed in turn. The numerical simulations are based on Mombasa Marine National Park, Kenya, a fully protected coral reef marine reserve comprising approximately 30% of former fishing grounds. Simulation results suggest that the establishment of a fully protected marine reserve will always lead to an increase in total fish biomass. If the fishery is moderately to heavily exploited, total fishery catch will be greater with the reserve in all scenarios of fish and larval movement. If the fishery faces low levels of exploitation, catches can be optimized without a reserve but with controlled fishing effort. With high fish migration from the reserve, catches are optimized with the reserve. The optimal area of the marine reserve depends on the exploitation rate in the neighboring fishing grounds. For example, if exploitation is maintained at 40%, the ‘optimal’ reserve size would be 10%. If the rate increases to 50%, then the reserve needs to be 30% of the management area in order to maximize catches. However, even in lower exploitation fisheries (below 40%), a small reserve (up to 20%) provides significantly higher gains in fish biomass than losses in catch. Marine reserves are a valuable fisheries management tool. To achieve maximum fishery benefits they should be complemented by fishing effort controls. 相似文献

8.

Mehdi Dehghan 《Numerical Methods for Partial Differential Equations》2002,18(2):193-202

Developement of numerical methods for obtaining approximate solutions to the three dimensional diffusion equation with an integral condition will be carried out. The numerical techniques discussed are based on the fully explicit (1,7) finite difference technique and the fully implicit (7,1) finite difference method and the (7,7) Crank‐Nicolson type finite difference formula. The new developed methods are tested on a problem. Truncation error analysis and numerical examples are used to illustrate the accuracy of the new algorithms. The results of numerical testing show that the numerical methods based on the finite difference techniques discussed in the present article produce good results. © 2002 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 18: 193–202, 2002; DOI 10.1002/num.1040 相似文献

9.

P. R. Latthe P. S. Shinge Bharati V. Badami P. B. Patil S. N. Holihosur 《Journal of Chemical Sciences》2006,118(3):249-256

3-[4-(Azidocarbonyl)]phenylsydnone (

**2**) obtained from 3-(4-hydrazinocarbonyl) phenylsydnone (**1**) on Curtius rearrangement with alcohols, water and amines afforded the corresponding carbamates (**3a-h**), 4,4′-(sydnone-3-yl) diphenyl urea (**4**) and 4-(heterocyclyl)phenyl ureas (**5a-l**). Compounds (**5a-l)**on one-pot ring conversion yielded the 1,3,4-oxadiazolin-2-one derivatives (**6a-l**), which on reaction with N_{2}H_{4}gave the 4-amino-1,2,4-triazolin-3-ones (**7a-l**). All these compounds exhibited moderate antimicrobial activity against the few microbes tested. The carbamates have been found to be more toxic against fourth instar larvae of*Aedes aegypti*, in particular, the*n*-butyl derivative (**3e**). 相似文献10.

We extend the matrix version of Cochran's statistical theorem to outer inverses of a matrix. As applications, we investigate the Wishartness and independence of matrix quadratic forms for Kronecker product covariance structures. 相似文献