Nachweis und Bestimmung des Eisens, sowie seine Trennung von anderen Elementen

Ohne Zusammenfassung     

成胶条件对耐高温高表面积氧化铝热稳定性的影响

 研究了氧化铝制备过程中的各种成胶条件（氨水滴加速度,pH值,温度和硝酸铝溶液的初始浓度等）对氧化铝热稳定性的影响,初步探讨了氧化铝的烧结机理．结果表明,各种成胶条件均可在一定程度上影响氧化铝的比表面积、孔容和平均孔径．选择适宜的制备条件能够阻止氧化铝在高温下烧结,改善氧化铝的孔结构,提高其热稳定性,从而制备出耐高温高比表面积的氧化铝．     

电热石墨炉分子吸收光谱法测定卤素的研究进展

本文评述了电热石墨炉分子吸收光谱法(MAS)及其在分析化学上测定卤素的近期进展,讨论了MAS测定卤素的基本原理。介绍了碱金属、碱土金属、第Ⅲ主族元素和一些重金属元素的双原子分子卤化物的分子吸收光谱MX(X=F,Cl,Br,I)。指出当用MX的吸收光谱测定卤素时,谱带宽度,背景吸收和共存离子干扰影响MAS法的应用。比较了原子吸收光谱法(AAS)和MAS在原理和应用两个方面的区别。介绍了利用双原子分子卤化物吸收光谱测定卤素的一些实际应用的领域:(1)海水和饮用水分析,(2)尿和血浆的分析,(3)在半导体或盐AgBr中测定Cl~-,(4)在环保中果树叶的分析,(5)化学试剂、原料分析     

水性丙烯酸系树脂涂料的制备、性能和应用

本文综述了丙烯酸系树脂涂料的发展概况、种类、制备方法和性能.     

3β,17α,21-三羟基-5α-孕甾-20酮-3β,21-双醋酸酯的微生物转化——化合物S的合成

以剑麻皂素(Tigogenin)制得的中间体3β,17α,21-三羟基-5α-孕甾-20酮-3β,21-双醋酸酯(3)为原料,经诺卡氏菌№ 8018(Nocardia sp.№ 8018)转化为化合物S(1)及少量的△~1化合物S(4)。可采用两种投料方式:用乙醇溶解投料(乙醇浓度为发酵液体积的0.2％),或用固体粉末(粒子为1μ左右)投料(浓度为0.5％),产率均为50％左右。     

Flash and continuous photolysis kinetic studies of the iron-iron hydrogenase model (μ-pdt)[Fe(CO)3]2 in different solvents

Flash and continuous photolysis studies of (μ-pdt)[Fe(CO)(3)](2) under excess CO were conducted in coordinating and noncoordinating solvents. The back-reaction of CO with the photoproduct showed second-order kinetics with k(CO) values of 1.0 × 10(8), 3.4 × 10(6), 1.2 × 10(6), and 0.90 M(-1) s(-1) in hexanes, benzene, toluene, and THF, respectively. These data indicate a solvent-coordinated intermediate as one photoproduct, but other long-lived species were also apparent.     

大型汽轮发电机转子护环热套应力测试技术研究

本文简要介绍了高温应变测量原理和技术在大型汽轮发电机转子护环热套应力测试中的成功应用.在现场测试工作中摸索出的热应力测试技术和方法是行之有效的,而且获得了满意的试验成果,探明了护环热套应力随温度变化的分布规律,为护环热强度性能和损伤机理的深入研究提供了实验依据.这一成功的测试技术,具有较大的工程意义.     

一个计算百分含量的公式

本文提出一个计算被测元素百分含量的公式。它确切、直观地反映了被测元素的浓度在标准系列浓度范围,超过甚至大大超过高、低标浓度时试液与空白的关系。我们引入关系常数n使三种关系在公式中直观地体现出来。     

Reactions of nitrogen oxides with heme models. Characterization of NO and NO2 dissociation from Fe(TPP)(NO2)(NO) by flash photolysis and rapid dilution techniques: Fe(TPP)(NO2) as an unstable intermediate

Described are studies directed toward elucidating the controversial chemistry relating to the solution phase reactions of nitric oxide with the iron(II) porphyrin complex Fe(TPP)(NO) (1, TPP = meso-tetraphenylporphinato2-). The only reaction observable with clean NO is the formation of the diamagnetic dinitrosyl species Fe(TPP)(NO)2 (2), and this is seen only at low temperatures (K(1) < 3 M(-1) at ambient temperature). However, 1 does readily react reversibly with N2O3 in the presence of excess NO to give the nitro nitrosyl complex Fe(TPP)(NO2)(NO) (3), suggesting that previous claims that 1 promotes NO disproportionation to give 3 may have been compromised by traces of air in the nitric oxide sources. It is also noted that 3 undergoes reversible loss of NO to give the elusive nitro species Fe(TPP)(NO2) (4), which has been implicated as a powerful oxygen atom transfer agent in reactions with various substrates. Furthermore, in the presence of excess NO2, the latter undergoes oxidation to the stable nitrato analogue Fe(TPP)(NO3) (5). Owing to such reactivity of Fe(TPP)(NO2), flash photolysis and stopped-flow kinetics rather than static techniques were necessary for the accurate measurement of dissociation equilibria characteristic of Fe(TPP)(NO2)(NO) in 298 K toluene solution. Flash photolysis of 3 resulted in competitive NO2 and NO dissociation to give Fe(TPP)(NO) and Fe(TPP)(NO2), respectively. The rate constant for the reaction of 1 with N2O3 to generate Fe(TPP)(NO2)(NO) was determined to be 1.8 x 10(6) M(-1) s(-1), and that for the NO reaction with 4 was similarly determined to be 4.2 x 10(5) M(-1) s(-1). Stopped-flow rapid dilution techniques were used to determine the rate constant for NO dissociation from 3 as 2.6 s(-1). The rapid dilution experiments also demonstrated that Fe(TPP)(NO2) readily undergoes further oxidation to give Fe(TPP)(NO3). The mechanistic implications of these observations are discussed, and it is suggested that NO2 liberated spontaneously from Fe(P)(NO2) may play a role in an important oxidative process involving this elusive species.     

Pricing vulnerable European options with stochastic default barriers

CF Lo and KC Ku Institute of Theoretical Physics and Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong, China Email: cho-hoi_hui{at}hkma.gov.hk Received on 31 July 2006. Accepted on 15 March 2007. This paper develops a valuation model of European options incorporatinga stochastic default barrier, which extends a constant defaultbarrier proposed in the Hull–White model. The defaultbarrier is considered as an option writer's liability. Closed-formsolutions of vulnerable European option values based on themodel are derived to study the impact of the stochastic defaultbarriers on option values. The numerical results show that negativecorrelation between the firm values and the stochastic defaultbarriers of option writers gives material reductions in optionvalues where the options are written by firms with leverageratios corresponding to BBB or BB ratings.