不同油酸加入量的纳米磁粉对磁性流体的性能影响

通过改变磁粉制备过程中的油酸加入量,来研究不同油酸加入量的磁粉对磁粉及磁性流体性能的影响。     

Showcase and window to the world: East German architecture abroad 1949–1990

For decades, German Democratic Republic (GDR) architecture was seen as parochial and dictated by the Soviets, yet increasing scholarly interest has generated a picture of debates and specific practices that were embedded in the global process of expansion and crisis of Modernism. Meanwhile, and influenced by the East-West conflict, competing concepts of modernization and national identity arose in the so-called Third World, initiating multifarious cultural transfer processes. This article analyses to what extent the architects from the GDR – a country whose building practice was increasingly shaped by the principles of industrial prefabrication – have played a part in regional contexts and construction methods. It also asks what their role was in international organizations such as Union Internationale des Architects and UNESCO, which promoted their practical engagement abroad. The subject raises issues of possible freedom of action in creative design and fusion processes, but also of bureaucratic constrictions and international relationships ending in unexpected conflicts. The examples outline the field of activities that stretches from pure blueprint delivery for a memorial competition to long-standing work on location when planning whole neighbourhoods. Furthermore, the article examines how the challenges of international planning impacted building culture within the GDR itself.     

生物提取用磁性微球的制备及其性能

磁性微球因其自身兼具高分子微球和磁性粒子的众多特性,广泛应用在细胞分离、固定化酶、靶向药物、分析检测、免疫测定等领域。本文通过化学共沉淀法制备了Fe3O4纳米粒子,并采用分散聚合法对其包覆,得到Fe3O4/SiO2磁性微球。研究结果表明,通过上述方法制备的磁性微球可以快速、有效的提取生物中的RNA,而且最佳的聚合反应温度为80℃。     

Direct observation of dipolar chains in iron ferrofluids by cryogenic electron microscopy

A key issue in research on ferrofluids (dispersions of magnetic colloids) is the effect of dipolar interactions on their structure and phase behaviour, which is not only important for practical applications but gives fundamental insight in dipolar fluids in general. In 1970, de Gennes and Pincus predicted a Van der Waals-like phase diagram and the presence of linear chains of particles in ferrofluids in zero magnetic field. Despite many experimental studies, no direct evidence of the existence of linear chains of dipoles has been reported in the absence of magnetic field, although simulations clearly show the presence of chain-like structures. Here, we show in situ linear dipolar structures in ferrofluids in zero field, visualized on the particle level by electron cryo-microscopy on thin, vitrified films of organic dispersions of monodisperse metallic iron particles. On systematically increasing the particle size, we find an abrupt transition from separate particles to randomly oriented linear aggregates and branched chains or networks. When vitrified in a permanent magnetic field, these chains align and form thick elongated structures, indicating lateral attraction between parallel dipole chains. These findings show that the experimental model used is well suited to study the structural properties of dipolar particle systems.     

Red flags and religious coping: identifying some religious warning signs among people in crisis

Particulate and soluble (1-3)-beta-glucans are effective in preventing infections by enhancing macrophage and neutrophil functions. However, the mechanisms triggering these enhanced cellular responses are essentially unknown. We recently demonstrated that zymosan, a particulate (1-3)-beta-glucan receptor agonist, caused an influx of Ca2+ in NR8383 rat alveolar macrophages (AMs) and a resulting increase in intracellular Ca2+ (Zhang et al., J. Leukoc. Biol. 62 (1997) 341-348). Since Ca2+ is important in mediating leukocyte responses, we investigated whether other (1-3)-beta-glucans also alter Ca2+ mobilization in AMs. Particulate and soluble (1-3)-beta-glucans derived from Saccharomyces cerevisiae were used in these studies. Like zymosan, particulate (1-3)-beta-glucan (WGPs) caused a concentration-dependent increase in [Ca2+]i, which was inhibited by removal of extracellular Ca2+ and by SKF96365, an inhibitor of receptor-operated Ca2+ channels. When three different soluble (1-3)-beta-glucans, with molecular weights of approximately 11,000, 150,000, and 1,000,000 Da, were tested alone for effects on Ca2+ responses, the low molecular weight (1-3)-beta-glucan produced no effect and the intermediate and high molecular weight (1-3)-beta-glucans caused only a small increase in [Ca2+]i. Interestingly, however, all three soluble (1-3)-beta-glucans could significantly reduce the Ca2+ responses induced by a subsequent exposure to either WGPs or zymosan. These results demonstrate that: 1) particulate (1-3)-beta-glucan activates Ca2+ influx in NR8383 macrophages through receptor-operated Ca2+ channels; 2) soluble (1-3)-beta-glucans do not strongly activate Ca2+ influx in these cells; and 3) soluble (1-3)-beta-glucans significantly inhibit Ca2+ influx induced by WGPs or zymosan. Soluble (1-3)-beta-glucans are likely to prevent Ca2+ influx by competitively binding to the (1-3)-beta-glucan receptors recognizing zymosan and WGPs. The smaller Ca2+ influx induced by soluble (1-3)-beta-glucans may represent only a partial activation of post-receptor signal transduction pathways necessary for inducing Ca2+ influx.     

Effects of inferior temporal lesions on visual discrimination performance in monkeys with complete and incomplete striate cortex ablations.

Eight male cynomolgus monkeys (Macaca fascicularis) were retrained to perform 2 preoperatively acquired discriminations (brightness-flux and brightness-area) after receiving bilateral striate cortex lesions to determine whether the inferior temporal cortex participates in the relearning of visual discriminations following striatectomy. Ss were then retested in the same tasks after bilateral inferior temporal surgery. After inferior temporal surgery, Ss with histologically verified total ablation of the striate cortex showed little or no impairment in relearning the discriminations, whereas Ss with remnants of intact striate cortex were severely impaired. Findings suggest that the inferior temporal cortex is of minor importance in relearning brightness-flux and brightness-area discriminations in the absence of striate cortex. This interpretation is consistent with the view that the contribution of the inferior temporal cortex to visual discrimination performance depends on input from striate cortex. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Haftfestigkeitsuntersuchungen an galvanischen Niederschlägen

Investigations on the Strength of Galvanic Deposits Pure nickel, nickel alloys, austenitic steel, copper and aluminium alloys were coated with adhesive and heat resisting layers of nickel or copper by electroplating. Production and examination of these metal connections was performed by specially developed methods. The investigations demonstrated, that high quality metal connections can be produced by electroplating. These connections will be of great interest for construction and fabrication.     

用于纺织机械减振的铸矿石

 在超宽型织机上用铸矿石充填机架侧壁可以避免弯曲振动.介绍了有限元计算和测试的结果.     

The effect of exposure to biological fluids on the spallation resistance of diamond-like carbon coatings on metallic substrates

Diamond-like carbon (DLC) films have been deposited by RF plasma-assisted glow discharge CVD on AISI 304 stainless steel and Ti–6Al–4V substrates. A substrate plastic straining technique (to measure the strength and adhesion of the coating) and erosion testing (to measure its durability) have been used, before and after exposure to various fluids (distilled water, phosphate buffered saline solution (PBS) and bovine serum). The films on both substrates had excellent adhesion before exposure to the fluid, being slightly higher for those on Ti substrates. PBS solution affected the adhesion adversely, whereas distilled water and serum had no apparent effect. Fourier transform infrared (FTIR) and Raman spectroscopic studies revealed that there were no changes in the atomic structure of the coatings during exposure. X-ray photoelectron spectroscopy (XPS) measurements indicated that PBS tends to penetrate through perforations in the film and attack the thin transition layer of graded Si/C composition between the a: Si–H layer and the DLC coating. An increase in exposure temperature increased the population of defects in samples exposed to PBS. Coatings on Ti exhibited similar characteristics, but were considerably more resistant to damage. This may be due to a lower incidence of defects and perforations in these films.     

二次表面修饰制备工艺的磁粉对磁性流体的性能提高

通过二次表面修饰技术制备磁粉,来对现有磁粉制备技术进行改进,进而提高现有磁粉的整体性能,并研究二次表面修饰技术制备磁粉对磁粉及磁性流体性能的影响。