Electro–Reaction–Diffusion Systems Including Cluster Reactions of Higher Order

In this paper we consider electro–reaction–diffusion systems modelling the transport of charged species in two–dimensional heterostructures. Our aim is to investigate the case that besides of reactions with source terms of at most second order so called cluster reactions of higher order are involved. We prove the unique solvability of the model equations and show the global boundedness and asymptotic properties of the solution. In order to get necessary a priori estimates we apply an anisotropic iteration scheme followed by usual Moser iterations. Then existence is obtained by cutting off the reaction terms.     

色散方程的四点显式差分格式

本文对色散方程u_t=au>_xxx构造了一类高稳定性的、在中间层涉及四个网格点的三层显式差分格式,其局部截断误差为O(τ+h),其稳定条件为|R|=|α|τ/h3≤0.25至|R|≤10,它们较大地改善了同类格式的稳定条件|R|≤0.25[1].     

组合化学、分子库与新药研究

组合化学是进入90 年代以来寻找及优化新药先导化合物的主要研究方法, 其特点是改变了传统的逐一合成、逐一纯化、逐一筛选的模式, 而是以合成和筛选化学库的形式完成寻找及优化药物先导化合物, 极大地加快了药物先导化合物出现的速度。本文就目前有关组合化学研究的基本理论、基本方法、发展趋势、研究成果以及我国应当采取的措施进行了综述。     

High Throughput Screening of the NatureBank ‘Marine Collection’ in a Haemonchus Bioassay Identifies Anthelmintic Activity in Extracts from a Range of Sponges from Australian Waters

Widespread resistance in parasitic nematodes to most classes of anthelmintic drugs demands the discovery and development of novel compounds with distinct mechanisms of action to complement strategic or integrated parasite control programs. Products from nature—which assume a diverse ‘chemical space’—have significant potential as a source of anthelmintic compounds. In the present study, we screened a collection of extracts (n = 7616) derived from marine invertebrates sampled from Australian waters in a high throughput bioassay for in vitro anti-parasitic activity against the barber’s pole worm (Haemonchus contortus)—an economically important parasitic nematode of livestock animals. In this high throughput screen (HTS), we identified 58 active extracts that reduced larval motility by ≥70% (at 90 h), equating to an overall ‘hit rate’ of ~0.8%. Of these 58 extracts, 16 also inhibited larval development by ≥80% (at 168 h) and/or induced ‘non-wild-type’ (abnormal) larval phenotypes with reference to ‘wild-type’ (normal) larvae not exposed to extract (negative controls). Most active extracts (54 of 58) originated from sponges, three from chordates (tunicates) and one from a coral; these extracts represented 37 distinct species/taxa of 23 families. An analysis of samples by ¹H NMR fingerprinting was utilised to dereplicate hits and to prioritise a set of 29 sponge samples for future chemical investigation. Overall, these results indicate that a range of sponge species from Australian waters represents a rich source of natural compounds with nematocidal or nematostatic properties. Our plan now is to focus on in-depth chemical investigations of the sample set prioritised herein.     

Integrable types of nonlinear ordinary differential equations of higher-orders

In this paper some integrable types of more general nonlinear ordinary differentialequations of higher-orders are proposed in virtue of Leibnitz formula,and formulas ofhigher-order derivatives of the composite functions as well as substitution vartables.Theexpressions for the general integrations of some of the equations are presented.The resultsobtained are the generalization of those in the references.Finally,some examples are alsogiven.     

Low-temperature heterogeneous oxidation of sulfide ions on a higher Co oxide system in aqueous medium

Low-temperature heterogenous oxidation of sulfide ions on a higher Co oxide system in aqueous medium has been studied. The effects of pH, temperature and catalyst amount on the kinetic parameters as well as on the selectivity of the oxidation process were investigated. An oxidation mechanism has been proposed based on the results of kinetic investigations and on the data obtained by IR and XPS spectroscopic studies of Co oxide before and after sulfide ion oxidation.     

Polling systems in heavy traffic: Higher moments of the delay

We study an asymmetric cyclic polling model with general mixtures of exhaustive and gated service, and with zero switch-over times, in heavy traffic. We derive closed-form expressions for all moments of the steady-state delay at each of the queues, under standard heavy-traffic scalings. The expressions obtained provide new and useful insights into the behavior of polling systems under heavy-load conditions. This revised version was published online in June 2006 with corrections to the Cover Date.     

关联余割函数的Hilbert型不等式及其应用

通过引入参数,构造了第一象限内的非齐次混合核函数,建立了常数因子最佳的Hilbert型积分不等式。利用余割函数的有理分式展开,证明了最佳常数因子可用余割函数的高阶导数表示。此外,通过对参数赋值,给出了若干特殊结论。     

Accuracy and stability of a set of free‐surface time‐domain boundary element models based on B‐splines

An analysis is given for the accuracy and stability of some perturbation‐based time‐domain boundary element models (BEMs) with B‐spline basis functions, solving hydrodynamic free‐surface problems, including forward speed effects. The spatial convergence rate is found as a function of the order of the B‐spline basis. It is shown that for all the models examined the mixed implicit–explicit Euler time integration scheme is correct to second order. Stability diagrams are found for models based on B‐splines of orders third through to sixth for two different time integration schemes. The stability analysis can be regarded as an extension of the analysis by Vada and Nakos [Vada T, Nakos DE. Time marching schemes for ship motion simulations. In Proceedings of the 8th International Workshop on Water Waves and Floating Bodies, St. John's, Newfoundland, Canada, 1993; 155–158] to include B‐splines of orders higher than three (piecewise quadratic polynomials) and to include finite water depth and a current at an oblique angle to the model grid. Copyright © 2000 John Wiley & Sons, Ltd.