Bildung von oxydischen Einschlüssen in halbberuhigtem Stahl

Untersuchung von 20-t-Blöcken mit unterschiedlichen Aluminiumzugaben für die Feindesoxydation während der Erstarrung in der Kokille. Oberflächenfehler von halbberuhigtem Stahl. Bildung von oxydischen Einschlüssen dicht unter der Blockoberfläche und im Blockinnern. Maßnahmen zur Beeinflussung der Einschlußausbildung.     

Action of prostaglandin, PGF2alpha, on the uterus of the pregnant rat

In a cytogenetic study on the spermatogonia of Chinese hamster, cyclohexylamine (neutral sulphate) was evaluated for mutagenic effects in comparison with an untreated control group and a group treated with the mutagenic compound cyclophosphamide, by assessing spermatogonial metaphases of treated Chinese hamster for chromosomal structural changes. Each test group comprised 8 male hamsters selected at random. Approximately 100 metaphases from each animal were assessed. The doses were 5 X 150 mg cyclohexylamine sulphate (approx. 5 X 102 mg base) per kg body-weight orally, and 5 X 100 mg cyclophosphamide per kg body-weight orally. The individual doses were administered at intervals of 24 h. Preparations were made 24 h after the final treatment, essentially by the method of Hoo and Bowles [10]. Gaps, breaks, fragments, deletions and translocations were assessed as structural changes; frequencies were determined of the metaphases (a) with aberration(s) including gaps, (b)with aberration(s) less gaps and (c)with translocation(s). Aberrations occurred in the untreated negative control group (1.24% incl. gaps, 0.25% without gaps). Translocations were not seen in the untreated group. In the cyclochexylamine group, the frequencies of the aberrant metaphases were sometimes less than in the control group (0.87% including gaps, 0.37% without gaps). Statistically, the results were not significantly different from the control data. No translocations were seen after administration of cyclohexylamine. The positive cyclophosphamide control group clearly differed from the untreated control and from the cyclohexylamine group in the parameters (a) to (c); mainly, the results were highly significantly different from those obtained in the untreated control group. The frequencies of the aberrant metaphases were 3.41% including gaps and 1.99% without gaps. The frequency of the translocations was 0.71% (5 out of 704). Cyclohexylamine sulphate, administered 5 times at 150 mg/kg body-weight orally, had no mutagenic effect, whereas cyclophosphamide, adminstered 5 times at 100 mg/kg body-weight orally, had a chromosome-damaging effect on Chinese hamster spermatogonia.     

Comparative investigation of the biocompatibility of various silicon nitride ceramic qualities in vitro

There is a controversy about the biocompatibility of silicon nitride ceramics contained in the literature, which appears to be related to a factor of the individual chemical composition of different qualities of silicon nitride ceramics and of the different surface properties. This study attempts to investigate the cytotoxicity of different qualities of industrial silicon nitride ceramics applying an L929-cell culture model in a direct contact assay combined with a cell viability assessment. Five different qualities of industrial standard silicon nitride ceramics were chosen for in vitro testing. The chemical composition was determined by EDS analysis. Different biomedically approved aluminium oxide qualities, a titanium alloy, glass and polyvinylchloride (PVC) served as control materials. L929 mice fibroblasts were incubated directly on the materials for 24 h, stained with bisbenzimide and propidium iodine for double fluorochromasia viability testing, and evaluated by inversion-fluorescence microscopy to control cell morphology, viability and cell counts compared to empty well values. Scanning electron microscopy was applied to additionally investigate cell morphology. There was no observation of cytotoxic effects on the silicon nitride ceramic samples; moreover cell morphology remained the same as on aluminium oxide and titanium. Viability testing revealed the presence of avital cells exclusively on PVC, which served as a negative control. Cell counts on all polished surfaces showed significantly higher numbers, whereas some rough surface samples showed significantly lower numbers. We conclude that silicon nitride ceramics show no cytotoxic effects and should be considered for biomedical application owing to its favourable physiochemical properties, especially its superior resistance to mechanical stress, which would be useful for compression loaded conditions. Polished surfaces would appear to promote advanced biocompatibility.     

源于共同的机械、电气和自动化设计的薄板坯连铸连轧工艺开发

西马克德马格公司在冶金工业方面是一个领先的工业工厂解决方案提供商.统一设计的机械、电气和自动化方案使我们的用户无论是在产品质量、产量、生产的灵活性、工艺的稳定性以及易维护性方面,拥有了生产具有高性能的高级材料的技术.在薄板坯连铸连轧领域,这样的共同开发的例子如下①CSP薄板坯连铸.结晶器液面控制,液压结晶器振动,用于楔形和速度优化的自动导航,带有LCR3(液芯压下)的液压扇形段调整,动态二冷水和结晶器监视系统;②CSP轧机.用于带材板形、连续凸度、平直度控制和自由轧制,采用了特定的磨辊以及相配套的串辊策略的CVC+技术;③用于实现厚度小于1mm带钢高效热轧的"薄规格技术包",包括采用"张力差活套"或"张力计活套"以及快速液压机构配合相应的自动化模块,如自动调平控制,以活套测量为基础的平直度控制,尾部监控或以楔形测量为基础的调平预设定.不仅是机械和电气的共同设计,还有共同的项目执行都将使工厂的运营者受益.例如,对于现代化改造项目和新安装的工厂,通过在交货之前在实验室内的联合测试,项目的投产时间得以优化."工厂回路测试(PILT)"将仿真或甚至机械部件本身与真实的自动化系统(1级,2级和人机界面HMI)结合在一起.通过这样的共同解决方案,西马克德马格公司在电气和自动化领域已发展成"从电机轴一直到生产计划系统"的成套供货商和系统集成商,其目标就是致力于与其用户的长期伙伴关系,并与用户分享其所拥有的工艺经验.     

Abiotic transformation of toxaphene by superreduced vitamin B12 and dicyanocobinamide

Toxaphene is a complex organochlorine pesticide mixture, residues of which are widespread in the environment. Previous studies with the isolated bacterium Sulfurospirillum (formerly Dehalospirillum) multivorans resulted in an effective anaerobic biotransformation of toxaphene. Since the bacterium contains a corrinoid derivative in the active center of the tetrachloroethene dehalogenase, we attempted to use superreduced corrinoids for abiotic transformation of toxaphene. The two corrinoids studied were dicyanocobinamide and cyanocobalamin (vitamin B12). Superreduced dicyanocobinamide mediated a rapid transformation of toxaphene. More than 90% of the initial pool was transformed within 6 h. The transformation was nonselective, and even the most persistent metabolite in environmental samples, the so-called dead-end metabolite 2-exo,3-endo,6-exo,8,9,10-hexachlorobornane (B6-923 or Hx-Sed) was transformed within hours. Superreduced cyanocobalamin was also able to transform toxaphene albeit at significantly lower velocity. The lack of transformation products detectable in gas chromatograms of hexanes-extracted fractions of the assays suggests rapid, sequential dehalogenation and/or destruction of the C10-hydrocarbon backbone of the compounds of technical toxaphene.     

High-power deuterium Raman laser at 632 nm

We demonstrate a continuous-wave deuterium Raman laser that generates more than 160 mW of Stokes output power despite severe thermal effects. This output power represents nearly an order-of-magnitude increase over any previously reported continuous-wave Raman laser and is the first such system to our knowledge that uses deuterium gas as the Raman medium. The high output power is achieved through careful consideration of the electronic feedback design, frequency actuators, and pump-laser intensity noise.