孔隙气体对断裂电磁辐射的影响及其机理

含瓦斯煤变形破坏时,孔隙气体是对电磁辐射产生影响的最重要因素之一。基于孔隙气体对电磁辐射影响的实验结果,运用分子动力学理论和方法建立了气体吸附动态平衡方程,详尽地叙述了孔隙气体与新形成的壁面间的相互作用,在此基础上建立了孔隙气体对电磁辐射影响的唯象模型,讨论了其微观机制。结果表明,孔隙中的自由瓦斯气体对电磁辐射没有明显的影响,而吸附瓦斯气体对电磁辐射有非常明显的影响。在临界瓦斯压力之前,吸附量越多,电磁辐射越弱;临界压力之后,吸附量越多,电磁辐射越强。     

External stimulus-responsive biomaterials designed for the culture and differentiation of ES,iPS, and adult stem cells

The physical and chemical characteristics of biomaterial surface and hydrogels can be altered by external stimuli, such as light irradiation, temperature changes, pH shifts, shear stress forces, electrical forces, and the addition of small chemical molecules. Such external stimulus-responsive biomaterials represent promising candidates that have been developed for the culture and differentiation of embryonic stem (ES) cells, induced pluripotent stem (iPS) cells, and adult stem cells. Biomaterials that are designed to respond in a reversible manner to specific external signals can be formed on micropatterned or non-micropatterned surface, in hydrogels, or on microcarriers. Stem cells and the cells differentiated from them into specific tissue lineages can be cultured and/or differentiated on dishes with immobilized external stimulus-responsive polymers. Cells can be detached from these dishes without using an enzymatic digestion method or a mechanical method when the appropriate external stimulus is generated on the surface. This review discusses the polymers and polymeric designs employed to produce surface and hydrogels for stem cell culture, differentiation, and/or cell detachment using various external stimuli.     

Self-assisted wound healing using piezoelectric and triboelectric nanogenerators

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Betel Nut Arecoline Induces Different Phases of Growth Arrest between Normal and Cancerous Prostate Cells through the Reactive Oxygen Species Pathway

Prostate cancer (PCa) is a reproductive system cancer in elderly men. We investigated the effects of betel nut arecoline on the growth of normal and cancerous prostate cells. Normal RWPE-1 prostate epithelial cells, androgen-independent PC-3 PCa cells, and androgen-dependent LNCaP PCa cells were used. Arecoline inhibited their growth in dose- and time-dependent manners. Arecoline caused RWPE-1 and PC-3 cell cycle arrest in the G2/M phase and LNCaP cell arrest in the G0/G1 phase. In RWPE-1 cells, arecoline increased the expression of cyclin-dependent kinase (CDK)-1, p21, and cyclins B1 and D3, decreased the expression of CDK2, and had no effects on CDK4 and cyclin D1 expression. In PC-3 cells, arecoline decreased CDK1, CDK2, CDK4, p21, p27, and cyclin D1 and D3 protein expression and increased cyclin B1 protein expression. In LNCaP cells, arecoline decreased CDK2, CDK4, and cyclin D1 expression; increased p21, p27, and cyclin D3 expression; had no effects on CDK1 and cyclin B1 expression. The antioxidant N-acetylcysteine blocked the arecoline-induced increase in reactive oxygen species production, decreased cell viability, altered the cell cycle, and changed the cell cycle regulatory protein levels. Thus, arecoline oxidant exerts differential effects on the cell cycle through modulations of regulatory proteins.     

Fabrication and Thermal Dissipation Properties of Carbon Nanofibers Derived from Electrospun Poly(Amic Acid) Carboxylate Salt Nanofibers

Polyimides (PIs) possess excellent mechanical properties, thermal stability, and chemical resistance and can be converted to carbon materials by thermal carbonization. The preparation of carbon nanomaterials by carbonizing PI‐based nanomaterials, however, has been less studied. In this work, the fabrication of PI nanofibers is investigated using electrospinning and their transformation to carbon nanofibers. Poly(amic acid) carboxylate salts (PAASs) solutions are first electrospun to form PAAS nanofibers. After the imidization and carbonization processes, PI and carbon nanofibers can then be obtained, respectively. The Raman spectra reveal that the carbon nanofibers are partially graphitized by the carbonization process. The diameters of the PI nanofibers are observed to be smaller than those of the PAAS nanofibers because of the formation of the more densely packed structures after the imidization processes; the diameters of the carbon nanofibers remain similar to those of the PI nanofibers after the carbonization process. The thermal dissipation behaviors of the PI and carbon nanofibers are also examined. The infrared images indicate that the transfer rates of thermal energy for the carbon nanofibers are higher than those for the PI nanofibers, due to the better thermal conductivity of carbon caused by the covalent sp² bonding between carbon atoms.     

Al-Ga-Mn-Ca-Cu合金电极碱性体系电化学性能

通过熔铸、压延、退火等一系列工艺制作了新型Al-0.017Ga-0.885Mn-0.038Ca-0.048Cu (wt.%)阳极合金,并通过了EIS、极化曲线分析研究了其在不同浓度NaOH溶液中的腐蚀行为和电化学性能。结果表明,随着NaOH浓度的增加,合金阳极的自腐蚀速率在逐渐增加,Al-0.017Ga-0.885Mn-0.038Ca-0.048Cu合金在4mol/LNaOH溶液中的腐蚀速率增长速度明显降低,放电电压在电流密度为120mA/cm2下仍能维持在1 V左右,阳极能量密度也最高,达6.056kW?h/kg,更适合不同电流密度下的连续恒流放电。且合金的恒流放电和EIS结果与腐蚀特性吻合较好。     

Flexural failure of unidirectional carbon/epoxy composites: Effects of interleaving and flexural rate

The effects of a low-modulus high-strain interleaf layer, introduced at the midplane, on unidirectional carbon/epoxy laminates under flexural loading were investigated. The apparent energy-to-fail of the laminates increased significantly whereas the maximum load decreased slightly upon interleaving. Real-time microscopic observations during static flexure tests at the lowest deflection rate indicated a dramatic change of failure mode from the dominantly compressive fracture of the baseline laminate to the dominantly tensile fracture process upon interleaving. Failure modes of interleaved and baseline laminates showed no significant changes with test rate in the deflection rate range of 10⁻⁶ to 10⁰ m/sec.     

分解炉循环喂料与物料停留时间分布的关系

:通过对外循环反应器的物料停留时间分布的研究 ,分析了带Pyrotop的分解炉内物料的循环比对物料平均停留时间的影响 ,为工厂的实际操作提供了理论根据     

核事故后果评价研究进展

回顾了国内外在核事故后果评价领域开展的概率风险评价、实时后果评价、事故后的后果评价技术与方法研究的发展历程,对后果评价研究在大气弥散模型的要求与发展、利用环境监测数据估算源项、食物链模型与事故季节性、剂量估算与防护措施、核与辐射突发事件（小尺度）响应、决策支持技术以及放射性物质长距离迁移问题等方面进行了讨论与分析。近年来,随着我国核能事业的迅猛发展,需要加强和发展核事故与突发事件的后果评价和应急响应技术。     

吸附材料植物多糖气凝胶的研究进展

在环境净化中,随着吸附材料功能性和环保性的双重要求,传统的吸附材料将逐渐退出市场。植物多糖气凝胶作为一种新型吸附材料,将逐渐取代传统吸附材料。本文系统地归纳了气凝胶的特性,并介绍了近年来植物多糖气凝胶用于水体中重金属离子的吸附、废水中染料的吸附、水体中有机污染物的吸附、水体中油污的吸附、污水中表面活性剂的吸附以及对空气中甲醛和二氧化碳吸附的研究进展。