Restricted rotation about the BN bond in aminoboranes: the determination of activation parameters using 13C NMR

In suitable cases, VT ¹³C NMR can provide a rapid and reliable method for obtaining activation parameters ΔH^★ and ΔS^★ for restricted rotation about the B  N bond in aminoboranes.     

Use of the augmented penalty function in mathematical programming problems,part 1

In this paper, the problem of minimizing a functionf(x) subject to a constraint (x)=0 is considered. Here,f is a scalar,x ann-vector, and aq-vector, withq<n. The use of the augmented penalty function is explored in connection with theordinary gradient algorithm. The augmented penalty functionW(x, ,k) is defined to be the linear combination of the augmented functionF(x, ) and the constraint errorP(x), where theq-vector is the Lagrange multiplier and the scalark is the penalty constant.The ordinary gradient algorithm is constructed in such a way that the following properties are satisfied in toto or in part: (a) descent property on the augmented penalty function, (b) descent property on the augmented function, (c) descent property on the constraint error, (d) constraint satisfaction on the average, or (e) individual constraint satisfaction. Properties (d) and (e) are employed to first order only.With the above considerations in mind, two classes of algorithms are developed. For algorithms of Class I, the multiplier is determined so that the error in the optimum condition is minimized for givenx; for algorithms of Class II, the multiplier is determined so that the constraint is satisfied to first order.Algorithms of Class I have properties (a), (b), (c) and include Algorithms (I-) and (I-). In the former algorithm, the penalty constant is held unchanged for all iterations; in the latter, the penalty constant is updated at each iteration so as to ensure satisfaction of property (d).Algorithms of Class II have properties (a), (c), (e) and include Algorithms (II-) and (II-). In the former algorithm, the penalty constant is held unchanged for all iterations; in the latter, the penalty constant is updated at each iteration so as to ensure satisfaction of property (b).Four numerical examples are presented. They show that algorithms of Class II exhibit faster convergence than algorithms of Class I and that algorithms of type () exhibit faster convergence than algorithms of type (). Therefore, Algorithm (II-) is the best among those analyzed. This is due to the fact that, in Algorithm (II-), individual constraint satisfaction is enforced and that descent properties hold for the augmented penalty function, the augmented function, and the constraint error.This research was supported by the National Science Foundation, Grant No. GP-27271. The authors are indebted to Dr. J. N. Damoulakis for analytical and numerical assistance. Discussions with Professor H. Y. Huang are acknowledged.     

Novel heteroaromatic silanes in the gas phase

The appearance of intense peaks, due to the (P—30)²⁺ ions, in the mass spectra of 8-trimethylsiloxyquinoline, 2-methyl-8-trimethylsiloxyquinoline, 2-trimethylsiloxymethylpyridine and 2-trimethylsiloxymethyl-6-methylpyridine suggests that these ions have considerable heteroaromatic character.     

基于惩罚与补贴的再制造闭环供应链网络均衡模型

为研究我国废旧电子产品(WEEE)立法的问题,分析了供应商、制造商、零售商、需求市场及回收商的行为,分别建立了变分不等式模型,并在此基础上建立了五级再制造闭环供应链网络均衡模型。模型考虑了政府对于制造商的惩罚政策与对于回收商的补贴政策。通过修正投影算法求解算例,仿真分析了旧材料转化率、回收率、惩罚及补贴政策对闭环供应链网络均衡结果的影响。结果表明,随着政府对于回收商的补贴的增加,不但回收商的回收量提高,闭环供应链的新材料需求量、旧材料需求量、销售量均增加;相反,随着政府对于制造商未完成的回收量的罚款增加,回收量、新材料需求量、旧材料需求量、销售量均降低;追求高回收率的政策并不总是有效的;而提高WEEE的旧材料转化率对于闭环供应链有利。     

Estimating rate constants in a convection-diffusion system with a boundary reaction

While performing biomolecular interaction analysis (BIA), scientistsoften use surface plasmon resonance (SPR) to measure rate constantsof the associated reactions. A mathematical model of a BIAcore^TM,a common SPR device, consists of a convection-diffusion equationin a channel with a reacting surface at the channel ceiling.Asymptotic and singular perturbation techniques are used toanalyse the concentration of the reacting species in two cases:when the reaction occurs much more slowly than diffusion, andwhen the reaction occurs on the same time-scale as diffusion.Linear and nonlinear integral equations result from the analysis;explicit and asymptotic solutions are constructed for physicallyrealizable cases. These expressions provide a direct way toestimate the rate constants from raw data.     

一种新型四硫富瓦烯衍生物的合成与表征

以二硫化碳和金属钠为基础物质合成了四硫富瓦烯（TTF）锌的配合物（TTF）Zn（NBu4）2。利用该化合物与苯甲酰氯反应得到的稳定化合物C17H10O2S5在甲醇钠溶液中与2,3-二溴丙醇反应成功合成出目标化合物（一种新配体）,其化学组成为C6H6OS5。利用IR谱、^1HNMR谱及元素分析对此化合物进行了表征。     

新大线同沟敷设热力分析

针对新大线同沟敷设管道,采用非结构化有限容积法,分析了不同的物性条件下,常温输送原油对加热输送原油的热力影响.     

对-叔丁基杯[8]芳烃键合硅胶制备及其毛细管电色谱性能研究

以γ-(环氧丙氧)丙基键合硅胶为前体,于硅胶表面键合环氧基,在催化剂存在下以杯芳烃钠盐开环制备杯芳烃键合硅胶固定相.该方法反应条件温和,适用性强.将这个新方法首次用于制备对-叔丁基杯[8]芳烃电色谱键合固定相(C8BS),采用加压电色谱初步评价其电色谱性能.研究结果表明,C8BS电渗流(Electrosmoticflow,EOF)较小,但通过控制键合反应及使用压力辅助电色谱可部分弥补上述不足.该固定相的EOF受流动相pH影响小(pH=3-8),同时大环配体屏蔽效应能有效地克服硅羟基引起的碱性化合物拖尾现象,这对电色谱分离具有重要意义.通过分步封尾研究EOF的来源发现,杯芳烃酚羟基对EOF有弱的贡献,这与报道的杯芳烃涂层具有径向电渗流调控能力相一致.