楔形头部试样的ECAP变形行为有限元模拟

应用三维有限元方法对楔形头部试样在等径弯曲通道挤压(ECAP)中的变形行为进行了模拟分析,以比较不同楔形方案(前楔形、后楔形以及楔形头部大小)对金属ECAP变形的影响.结果表明:试样头部为后楔形可以有效的降低加工载荷,显著改善应力/应变分布的均匀性,消除应变集中,避免折叠缺陷,从而获得组织性能较为均匀的试样.     

Lycium barbarum polysaccharide inhibits the proliferation of HeLa cells by inducing apoptosis

BACKGROUND: Lycium barbarum polysaccharide (LBP), isolated with boiling water from the famous Chinese medicinal herb Lycium barbarum fruits, is one of the most important functional constituents in Lycium barbarum. In this study the effects of LBP on cell proliferation, cell cycle and apoptosis in human cervical carcinoma cells (HeLa cells) were investigated. RESULTS: LBP could inhibit the proliferation of HeLa cells by changing cell cycle distribution and inducing apoptosis. In addition, the loss of mitochondrial transmembrane potential (Δψ_m) was observed by flow cytometry and the increase of intracellular Ca²⁺ concentration was detected by laser scanning confocal microscope in apoptotic cells. At the same time, the nitric oxide content, nitric oxide synthase and inducible nitric oxide synthase activities were also increased. CONCLUSION: The inhibitory effect of LBP on the proliferation of HeLa cells was caused by inducing apoptosis through the mitochondrial pathway. The results showed that LBP can be developed as a potential chemotherapeutic agent candidate against human cervical cancer. Copyright © 2012 Society of Chemical Industry     

Potential Barrier Heights and Phase Transition in Polyphenyls and Poly(p-Phenylene)

Abstract

The analysis from X-ray or neutron diffraction data, of the unusually high librational motion around the long molecular axis of the p-terphenyl central ring, reveals a doubly-peaked probability density function (p.d.f.), associated with a double-well potential function between two twisted conformations (φ = ± 13.3° on either side of the average molecular plane). This p.d.f. is the pretransitional effect of an order-disorder transition which takes place at low-temperature. With a simple model averaging the intermolecular interactions, it is possible to separate in the overall libration on each site, at the bottoms of the double well, the contribution of the torsional g mode (θ²) = 35 deg², responsible for the jumps above the barrier, from the contribution of the other modes (θ²) = 17.5 deg². Thus it becomes possible to determine the parameters of the model describing the intermolecular, as well as the intramolecular interactions and to specify the non-sinusoidal shape of the intramolecular potential between two adjacent phenyl rings. It is straightforward to extend the model to any p-polyphenyl molecule with any number of phenyl rings, by considering that the molecular packings are the same in all the family. The model gives an estimate of the reorientational potential barrier heights V = 4.57 kJ mol^?1 in p-terphenyl, V = 7.91 kJ mol^?1 in p-quaterphenyl, in good agreement with NMR results; the calculated p.d.f. are doubly peaked and V < kT at room temperature, which characterizes order-disorder transitions. On the other hand, the model gives a singly peaked p.d.f. and V = 1.25 kJ mol^?1 < kT in crystalline biphenyl, which agrees with the displacive nature of the phase transition. Combined with the features of the incommensurate phase of biphenyl at T = 20K, it gives an estimate of the interactions involved in the modulated phase, predicting a large increase of intermolecular interactions in biphenyl at low-temperature. Finally it is applied to poly(p-phenylene), predicting a twisted conformation in agreement with recent diffraction results and high reorientational barrier potentials.     

6/8极双绕组电机环流实例分析与对策

6/8极双速电机功率为53kW/23kW。因功率相差较大,故设计时采用双绕组,但产生环流使电机不能起动。文章分析了环流产生的原因并提出了解决方法。     

Entry into imaginary space: Metaphors of transition and variations in the affective quality of potential space in children’s literature.

In this article the authors use the imaginal worlds of three children’s stories to explore variations in the affective quality of potential space. Lewis Carroll’s Alice in Wonderland, C. S. Lewis’ The Lion, the Witch, and the Wardrobe, and Norton Juster’s The Phantom Toolbooth, each contain a metaphor of transition in which the protagonist moves from the real space of the narrative into the imaginary space where the action takes place—the protagonists are altered and alter their own worlds. The authors will use these metaphors as analogues to differing qualities of imaginary space, including the collapse of meaning in schizoid states, the play of meaning in mentalization and the adventurousness of negotiating separation. These metaphors of transitioning into imaginary space may be used to think about disruptions in development as they manifest in clinical process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

二氧化氯选择性浸出分离废弃线路板中贵贱金属研究

废弃线路板经破碎预处理后,用二氧化氯作为氧化剂,通过控制浸出体系电位+380~400 mV,在盐酸浓度2 mol/L,温度80℃,液固比8∶1,反应时间2.5 h的实验条件下,贱金属铜、铅和锡的浸出率分别为97.4%,96.2%,和97.2%,金银很少浸出留在浸出渣中,从而实现贵贱金属有效分离。     

Reuse potential of municipal wastewater treatment facility effluents for sustainable water resource management in Ulsan,Korea

Effluent qualities of five municipal wastewater treatment facilities (MWWTFs) in Ulsan were evaluated to examine their reuse potential. Effluent from Yongyeon (Y) MWWTF, Onsan (O) MWWTF and Bangeojin (B) MWWTFs can be used as cooling water without further treatment. As evident from Langelier saturation index and Ryzner index values, reuse of treated effluent from OMWWTF and BMWWTFs is recommended by controlling the pH to reduce the scale-forming potential of effluent. However, effluents from these MWWTFs need additional treatment to remove residual dissolved constituents before reuse as boiler water. Besides, effluent from Hoiya (H) MWWTF and Unyang (U) MWWTFs can be reused for agricultural irrigation without any additional treatment. Based on the scientific results obtained from this investigation, proper application of technology and promotion of public awareness to change the traditional mindset for treated effluent reuse could immensely contribute towards conserving local water resources and addressing global environmental problems on a regional basis.     

Measurement of potential distribution function on object surface by using an electron microscope in the mirror operation mode

The quantitative theory of image contrast in an electron microscope in the mirror operation mode is given in this paper. This theory permits us to calculate the potential distribution on the object surface from the current density distribution on the microscope screen. The potential distribution results in image formation on the screen. Local electric fields existing on the object surface lead to a perturbation of electron trajectories above the object and to a redistribution of the current density on the screen, causing image contrast. Using the quantitative correlation between these fields and the function of current density distribution on the screen, it is possible to calculate the magnitude of these microfields as well. As illustration, a measured potential distribution on an object surface with spiral structures of adsorbates was analysed. These structures are formed during reaction of CO oxidation on Pt(110). The value of the measured contact potential difference comprised a few hundredths of volt.     

Electronic States and Light Absorption in a Cylindrical Quantum Dot Having Thin Falciform Cross Section

Energy level structure and direct light absorption in a cylindrical quantum dot (CQD), having thin falciform cross section, are studied within the framework of the adiabatic approximation. An analytical expression for the energy spectrum of the particle is obtained. For the one-dimensional “fast” subsystem, an oscillatory dependence of the wave function amplitude on the cross section parameters is revealed. For treatment of the “slow” subsystem, parabolic and modified Pöschl-Teller effective potentials are used. It is shown that the low-energy levels of the spectrum are equidistant. In the strong quantization regime, the absorption coefficient and edge frequencies are calculated. Selection rules for the corresponding quantum transitions are obtained.