A hybrid-stress solid-shell element for non-linear analysis of piezoelectric structures

This paper presents eight-node solid-shell elements for geometric non-linear analyze of piezoelectric structures.To subdue shear,trapezoidal and thickness locking,the assumed natural strain method and an ad hoc modified generalized laminate stiffness matrix are employed.With the generalized stresses arising from the modified generalized laminate stiffness matrix assumed to be independent from the ones obtained from the displacement,an extended Hellinger-Reissner functional can be derived.By choosing the ass...     

On fractional control method for four-wheel-steering vehicle

Four-wheel-steering (4WS) system can enhance vehicle cornering ability by steering the rear wheels in accordance with the front wheels steering and vehicle status.With such steering control system,it becomes possible to improve the lateral stability and handling performance.In this paper,a new control method for 4WS vehicle is proposed,its rear wheels steering angle is in accordance with the angle of front wheels steering and vehicle yaw rate,and the effects of front wheels steering angle velocity are consi...     

Recruitment and retention: factors that affect pericyte migration

Pericytes are critical for vascular morphogenesis and contribute to several pathologies, including cancer development and progression. The mechanisms governing pericyte migration and differentiation are complex and have not been fully established. Current literature suggests that platelet-derived growth factor/platelet-derived growth factor receptor-β, sphingosine 1-phosphate/endothelial differentiation gene-1, angiopoietin-1/tyrosine kinase with immunoglobulin-like and EGF-like domains 2, angiopoietin-2/tyrosine kinase with immunoglobulin-like and EGF-like domains 2, transforming growth factor β/activin receptor-like kinase 1, transforming growth factor β/activin receptor-like kinase 5, Semaphorin-3A/Neuropilin, and matrix metalloproteinase activity regulate the recruitment of pericytes to nascent vessels. Interestingly, many of these pathways are directly affected by secreted protein acidic and rich in cysteine (SPARC). Here, we summarize the function of these factors in pericyte migration and discuss if and how SPARC might influence these activities and thus provide an additional layer of control for the recruitment of vascular support cells. Additionally, the consequences of targeted inhibition of pericytes in tumors and the current understanding of pericyte recruitment in pathological environments are discussed.     

华南贵东杂岩体单颗粒锆石激光探针ICPMS U-Pb定年及其成岩意义

系统的单颗粒锆石激光探针ICPMS U-Pb同位素定年表明, 贵东杂岩体是印支期~燕山期多次岩浆侵入形成的复式杂岩体, 其中鲁溪岩体(239 ± 5 Ma)、下庄岩体(235.8 ± 7.6 Ma)是印支期花岗岩; 隘子岩体(160.1 ± 6.1 Ma)、司前岩体(151 ± 11 Ma)是燕山期花岗岩. 下庄岩体中1275~2137 Ma残留锆石的发现, 表明贵东花岗岩杂岩体的物质来源与华南元古宙陆壳基底有关. 详细的单颗粒锆石激光探针ICPMS U-Pb同位素定年为研究该杂岩体的形成演化与构造作用、成矿作用的关系提供了重要的依据.     

Unscheduled CDK1 activity in G1 phase of the cell cycle triggers apoptosis in X-irradiated lymphocytic leukemia cells

Cyclin-dependent kinase 1 (CDK1) is a major component of the cell cycle progression engine. Recently, several investigations provided evidence demonstrating that unscheduled CDK1 activation may also be involved in apoptosis in cancerous cells. In this article, we demonstrate that X-ray irradiation induced G1 arrest in MOLT-4 lymphocytic leukemia cells, the arrest being accompanied by reduction in the activity of CDK2, but increased CDK1 activity and cell apoptosis in the G1 phase. Interestingly, this increase in CDK1 and apoptosis by ionizing radiation was prevented by pretreatment with the CDK1 inhibitor, roscovitine, suggesting that CDK1 kinase activity is required for radiation-induced apoptotic cell death in this model system. Furthermore, cyclin B1 and CDK1 were detected co-localizing and associating in G1 phase MOLT-4 cells, with the cellular lysates from these cells revealing a genotoxic stress-induced increase in CDK1 phosphorylation (Thr-161) and dephosphorylation (Tyr-15), as analyzed by postsorting immunoprecipitation and immunoblotting. Finally, X-irradiation was found to increase Bcl-2 phosphorylation in G1 phase cells. Taken together, these novel findings suggest that CDK1 is activated by unscheduled accumulation of cyclin B1 in G1 phase cells exposed to X-ray, and that CDK1 activation, at the wrong time and in the wrong phase, may directly or indirectly trigger a Bcl-2-dependent signaling pathway leading to apoptotic cell death in MOLT-4 cells. Received 30 March 2006; received after revision 23 June 2006; accepted 24 August 2006 J. Wu and Y. Feng contributed equally to this work.     

Selective antiproliferative effects of thymidine

A substance with antiproliferative bioactivity in an aqueous extract ofCordyline terminalis was purified and identified by mass spectrometry to be the natural nucleoside, thymidine. 10^–5M Thymidine inhibited EL4 cell replication and decreased cell viability after 12–24 h. The effect was highly specific for this nucleoside. Treated cell cultures showed a significant increase in S phase cells and a corresponding decrease in G₁ phase cells. Nitrobenzylthioinosine (which prevented facilitated entry of thymidine) protected cells from the antiproliferative action of thymidine. A human breast cancer cell line (MCF7) was also growth-inhibited by 10^–5M thymidine but a murine lymphoma cell line (K36) was not. Thus, submillimolar thymidine has effects on cell proliferation which are selective both with respect to specificity for the compound and for different tumour cell lines.     

Dopamine-beta-hydroxylase activity in stroke-prone spontaneously hypertensive rats

Dopamine-beta-hydroxylase (DBH) activity was higher in the serum, the mesenteric artery and the cerebral cortex of 4-week-old stroke-prone spontaneously hypertensive rats (SHRSP), and lower in the nucleus tractus solitarii than it was in spontaneously hypertensive rats (SHR).