薄层树脂相分光光度法测定钢铁中磷

提出了在强酸性条件下 ,以薄层树脂相分光光度法测定磷。此方法灵敏度高 (ε70 5=9. 7× 10 5) ,精密度好 (测含磷1μg/mL样品 6次 ,RSD =0.83 % ) ,线性范围为 0.1～ 1. 2 μgP/mL ,回收率达 96.0 %～ 99.4%。     

负载树脂预富集薄层树脂相分光光度法测定痕量镁

以阳离子交换树脂为载体 ,显色剂偶氮氯膦I与缔合在树脂上的Mg 络合 ,薄层树脂相分光光度法测定痕量镁。络合物最大吸收波长为 5 70nm ,表观摩尔吸光系数ε570 =2.4× 10 5,灵敏度比水相光度法提高 12 6倍。方法线性范围 0～12 μg/mL ,检出限 0 15 μg/L。对 10 μgMg 测定 6次 ,RSD =1 .3 7% ,实测了二次精制盐水中镁 ,回收率 99%～ 10 0. 5 %。     

Effect of magnetic layer thickness on magnetic properties of Ce-Fe-B thin films

The Ce_2 Fe_(14)B thin films with a notable out-of-plane c-axis texture were prepared by DC magnetron sputtering on a Ta buffer layer. The morphological and magnetic properties were investigated. The thickness of the magnetic layer had a dramatic effect on the formation of Ce_2 Fe_(14)B phase,and excellent magnetic properties(H_(ci)≈4.25 kOe, M_r/M_s≈0.81) were observed for the Ce-Fe-B film with the thickness d_m = 200 nm. The results of the hysteresis loops for Ce-Fe-B film(d_m = 200 nm) at various measured temperatures show that a decoupling between the hard and the soft phases is observed at low temperatures, which is due to the regions with quite low anisotropy provided by the a-Fe. Moreover. it is clear that significantly various magnetization behaviors between the films with d_m = 200 and 300 nm were observed with a similar trend due to the existence of the a-Fe soft phase.     

层状复合粉末冶金凸轮的装配应力

利用三维有限元方法建立层状复合凸轮与钢管的过盈装配模型,模拟过盈装配过程中凸轮等效应力的分布规律以及不同内层材料和内层厚度对凸轮装配内应力的缓解效果,并进行实验验证。结果表明:与45#钢内层材料相比,粉末冶金材料(Fe-Cu-C)具有更好的缓解应力效果,在过盈量为0.08 mm时,复合凸轮表面应力仅为前者的38%,实验验证表面应力为前者的40%,误差仅为5%,模拟与实验结果基本一致。利用该模型对复合凸轮的层状厚度进行了优化设计,内层厚度允许范围为1.75~2.25 mm,最佳厚度为2.05 mm。     

Optimizing form and function with the direct posterior composite resin: a case report

The human testis determining factor (SRY) has been cloned from the Y chromosome. This gene is a dominant inducer of male differentiation. Mutations in the SRY gene result in an XY individual developing as a sex reversed phenotypic female. Sex reversal in humans can also be caused by mutations located in autosomal or X-linked loci. One such sex-reversing locus (SRAI) is associated with the developmental disorder campomelic dysplasia (CD). Both these syndromes were mapped to human chromosome 17q by the identification of balanced reciprocal translocations in five unrelated patients. The translocation breakpoint of one such XY-female CD patient was mapped and the region surrounding it cloned. The closest distal marker used to map the translocation breakpoint was the SOX9 gene. Because of the close proximity of this gene to the breakpoint, it was subjected to mutation analysis in patients without overt chromosome rearrangements. Analysis of DNA from these patients and their parents identified de novo mutations in the SOX9 gene in patients with both autosomal sex reversal and CD. This showed that mutations in the SOX9 gene are responsible for both syndromes.     

Modelling molten flux layer thickness profiles in compact strip process moulds for continuous thin slab casting

Abstract

The important functions promoted by powdered flux added over the liquid steel surface in continuous casting moulds are strongly affected by the thickness of the liquid layer that forms as a result of the heat absorbed. The present work discusses the results of a three-dimensional steady state model, developed to represent the coupled fluid flow and heat transfer phenomena that determine thickness profiles of the liquid flux layer. Since the laminar flow of the liquid slag layer depends on the shearing imposed on it by the turbulent motion of the liquid steel beneath it, and since additionally this motion is strongly influenced by the flow characteristics of the steel stream poured into the mould through the submerged entry nozzle (SEN), separate turbulent flow models for the liquid steel in the SEN and the mould were also developed. The consistency among the models and their accuracy was judged by comparing thickness and temperature flux profiles measured in plant against predicted ones; the comparison showed good agreement. The effects of casting speed, mould width, and flux viscosity and heat of melting on the liquid layer thickness were investigated. The last variable was found to exert the most marked influence. Different from conventional casting moulds, where the liquid layer thickness increases with increasing casting speed, in compact strip process moulds the thickness remains almost constant with increasing casting speed. This difference is well accounted for by the model, which suggests that this behaviour stems from the different slag flow patterns generated in straight, wide moulds and in thin moulds having a central upper funnel shaped section.     

Slice thickness of spiral CT images as function of pitch

Latex is a ubiquitous part of life today. It is a constituent of many household products and medical devices, although not always obvious on examination. The increase in incidence of potentially life-threatening allergic reactions to latex has been a cause for mounting concern over recent years. Although there have been recent reviews of the general problem of latex allergy, there is little advice available to anaesthetists on how to develop an effective strategy to implement within their own hospitals. The aim of this article is to improve awareness of latex allergy and by describing the development of our strategy to identify and safely manage those at risk in the peri-operative period, facilitate the process for other departments.     

FeⅡ-紫脲酸体系薄层树脂相光度法测定痕量铁的研究

提出了在碱性条件下 ,利用薄层树脂相分光光度法测定痕量铁的新方法。将Fe 与紫脲酸形成的络阴离子 ,吸附在717型阴离子交换树脂上 ,通过薄层树脂相光度法测定铁。方法灵敏度高 ,ε6 2 0 =3.0× 10 5,比水相光度法灵敏度提高 15倍。精密度理想 ,测定含 5 μgFe 溶液 6次 ,RSD =1.8%。实测天然水中痕量铁 ,加标回收率为 97%～ 99%。     

Scanning electron microscopic evaluation of two compaction techniques using a composite resin as a root canal filling material

The canals of 20 human dental roots were instrumented using a a step- back technique. The smear layer was removed, and the canals were obturated with composite resin. Two different techniques of compaction were used: either vertical or lateral motions were used to condense composite resin inside the root canal that was then photopolymerized layer by layer using the argon laser (488 nm). The beam was delivered into the root canal by means of an optical fiber 320 micrometers in diameter. Longitudinal and cross-sections of the samples and resin replicas of the root canals were examined using a light and scanning electron microscope. Scanning electron microscopic examination revealed that laterally compacted resin fillings showed fewer voids than those obtained by vertical compaction. In both experimental groups, adhesion of the resin to the dentin walls, pulled-out resin tags, microfailure, and resin fracture, leaving a layer of resin associated with the wall surface were observed.