NADP-isocitric dehydrogenase of gerbil adrenal mitochondria: Support of steroid hydroxylation

Summary In gerbil adrenal cortex the activity of intramitochondrial NADP-linked isocitric dehydrogenase (IDH) is up to 10-fold greater than the NAD-linked IDH. The NADP-IDH, apparent K_m 0.58 mM, V_max 280 nmoles/min/mg mitochondrial protein, appears to be the major source of reducing equivalents to support adrenal mitochondrial steroid 11B- and 19-hydroxylation in this species.     

Androstenedione or corticosterone treatment during pregnancy alters estrous cycle of adult female offspring in mice

Summary Female offspring from mice injected with androstenedione during late pregnancy showed lengthened vaginal cycles, persistent estrus and decreased incidence of pro-estrus and dïestrus, whilst offspring from mice injected with corticosterone showed increased incidence of dïestrus. These observations give qualified support to the hypothesis that stress during pregnancy alters the female offspring reproductive system through the action of adrenal steroids.     

Possible existence of a presynaptic positive feedback mechanism enhancing dopamine transmission in the anterior cingulate cortex of the rat

A series of microiontophoretic and VTA stimulation experiments, conducted in intact, GBR-12909-treated, alpha-methylparatyrosine-depleted or 6-hydroxydopamine-denervated rats, provide suggestive evidence for the existence of a presynaptic, positive feedback mechanism triggered by dopamine reuptake and favoring the release of this transmitter in the anterior cingulate cortex.     

A somatotopic organization of leg afferents in the spiderCupiennius salei Keys. (Araneae,Ctenidae)

Summary Axonal anterograde degeneration after ablation of different leg segments of the spiderCupiennius salei was traced using LM-and EM-methods. The pattern of degeneration seen in cross sections of the leg nerves close to their entry into the subesophageal ganglion shows a somatotopic organization of afferents within the leg nerves coming from different leg segments. All afferents run through the ventral part of the nerve.Acknowledgment. We thank Dr E.A. Seyfarth for helpful discussions. Parts of the study were supported by the Deutsche Forschungsgemeinschaft (W.G., SFB45/A1).     

Starvation and penetration of bacteria in soils and rocks

Summary The soil and subsurface strata are low nutrient environments and their bacterial inhabitants must adopt starvation responses to survive. These responses include the formation of dormant, viable cells which, although reduced in cell size and volume, are able to respond to any improvement in nutrient availability. Starved bacteria are able to survive for extended periods without nutrients and their reduced size allows them to disperse deeply within rocks and soils greatly improving their penetration. These combined factors may increase opportunities for bacteria to reach a deep waste disposal site.     

Macroscopic Quantum Phenomena and Topological Phase Interference Effects in Single-Domain Magnets

The tunneling of macroscopic object is one of the most fascinating phenomena in condensed matter physics. During the last decade, the problem of quantum tunneling of magnetization in nanometer-scale magnets has attracted a great deal of theoretical and experimental interest. A review of recent theoretical research of the macroscopic quantum phenomena in nanometer-scale single-domain magnets is presented in this paper. It includes macroscopic quantum tunneling (MQT) and coherence (MQC) in single-domain magnetic particles, the topological phase interference or spin-parity effects, and tunneling of magnetization in an arbitrarily directed magnetic field. The general formulas are shown to evaluate the tunneling rate and the tunneling level splitting for single-domain AFM particles. A nontrivial generalization of Kramers degeneracy for double-well system is provided to coherently spin tunneling for spin systems with m-fold rotational symmetry. The effects induced by the external magnetic field have been studied, where the field is along the easy, medium, hard axis, or arbitrary direction.     

杂多钨酸及其盐对碳钢的缓蚀作用

采用失重法研究了部分杂多化合物在水介质中对碳钢的缓蚀作用。实验结果表明，所研究的１１种杂多化合物对碳钢均具有一定的缓蚀作用。其中，Ｎａ８Ｈ［ＰＷ９Ｏ３４］·ｘＨ２Ｏ和Ｎａ１０［α－ＳｉＷ９Ｏ３４］·ｘＨ２Ｏ等缺位化合物的缓蚀效果较好，它们的最佳缓蚀浓度分别为１０５０～１１５０ｍｇ／Ｌ和５００～６００ｍｇ／Ｌ。从杂多化合物的性质及实验过程所发生的现象推测，所研究的杂多化合物为复合型缓蚀剂     

数学建模与21世纪公民数学素质的培养

通过分析２１ 世纪社会的特征及未来公民应具备的数学素质结构， 探讨了数学建模对２１ 世纪公民数学素质培养的作用