美国高科技行业人力资本、知识产权资本的“印度化”研究——兼论中国硅谷怎样成为“移民发动机”

目前．印度已率先进入人才、资本双重驱动的“公司化知识经济移民时代”,由此,美国高科技行业人力资本、知识产权资本已形成“印度化”趁势。从发展态势看．包括苏州在内,中国一大批硅谷也能成为中国知识经济移民大规模进驻西方就业市场的“移民发动机”。从发展潜力看．中国进入“公司化知识经济移民时代”的规模和力度将远远超过印度。中国的科技崛起．可能绕不过美国高科技行业人力资本、知识产权资本的“中国化”阶段。     

Building well-defined hierarchical nanostructures for sulfur and silicon electrodes

Huge volume expansion of electrode materials (e.g. 80% for sulfur and 310% for silicon) in the electrochemical lithiation reaction is seen as a root-cause of fast capacity fading of rechargeable lithium batteries. In this work, an effective solution is demonstrated by fabricating thin film sulfur and silicon electrodes with hierarchical structure of sulfur (or silicon) particles sandwiched between adjacent reduced graphene oxide (rGO) layers. The hierarchical films are constructed via vacuum filtration assisted layer-by-layer assembly of rGO and the respective precursor particles, i.e. zinc sulfide or silica shelled by super-sticky polydopamine. Polydopamine serves as a glue of rGO layers to furnish good mechanical integrity to the structure, and the precursor of nitrogen-doped carbon upon high-temperature calcination to ensure the electrical contacts between rGO layers. Zinc sulfide is oxidized to the electrochemically active sulfur by soaking in ferric aqueous solution, while silica is reduced to nanosized silicon in magnesium vapor at high temperature. The electrochemical studies reveal that the binder-free hierarchical electrodes can tolerate the volume change upon lithiation/delithiation, giving high initial Coulombic efficiency and good capacity retention. The rGO layers in the sulfur electrode is also found to effectively mitigate the diffusion of polysulfides into electrolyte.     

石墨相氮化碳（g-C3N4）光催化分解水制氢材料的研究进展

石墨相氮化碳（g-C3N4）具有环境友好、组成元素含量丰富、原料廉价和可规模化制备等优势,成为可见光半导体材料研究的重点。本文从g-C3N4的掺杂、纳米尺度形貌控制、构筑多孔结构、表面异质结和组装析氧活性电催化剂等角度概述了相关的研究进展。     

氮化物无限抛物量子阱中极化子能量

采用LLP变分法研究氮化物抛物量子阱（GaN／Al0.3Ga0.7N）材料中自由极化子的能级,给出基态能量和基态到第一激发态跃迁能量随抛物量子阱宽度变化的函数关系．研究结果表明,自由极化子基态能量和跃迁能量随着阱宽的增大首先急剧减小,然后缓慢下降,最后接近GaN体材料中的三维值．这些结果在定性上与GaAs／ALGa1-x,As抛物量子阱中的值相似,但在定量上有所不同．GaN／Al0.3Ga0.7N抛物量子阱中电子一声子相互作用对极化子能量的贡献明显大于GaAs／Al0.3Ga0.7N抛物量子阱中的相应值,因此,讨论氮化物抛物量子阱中的电子态问题时应考虑电子一声子相互作用．     

硅对盐胁迫下金丝小枣叶绿素荧光参数和气体交换的影响

以2年生嫁接苗为试材,研究了硅对盐胁迫下金丝小枣光合生理的影响。结果表明:金丝小枣在含3.0和5.0 g/kg NaCl土壤中生长135 d,叶绿素(Chl)含量分别降低12.30%和22.08%,加硅比不加硅Chl含量分别提高9.26%和10.62%;光系统 II(PSII)的潜在化学活性(Fv/Fo)和最大光化学效率(Fv/Fm)分别下降19.96%,34.58%和 8. 86%, 14. 10%,加硅比不加硅 Fv/Fo 和 Fv/Fm 分别提高 32. 25%, 30. 71%和11.26%,12.15%;光合速率(Pn)和气孔导度(Gs)分别下降 11.04%,25.32%和 26.13%,16.22%,加硅比不加硅Pn和Gs 分别提高10.94%,20.87%和42.68%,10.85%。说明盐胁迫下给土壤施硅可缓解盐离子对金丝小枣光合作用的抑制与伤害。     

硅基转接板上传输线的电学特性

对硅基转接板上单层RDL(redistribution layer)和多层RDL传输线的损耗特性进行了深入的分析和比较。研究了硅的电阻率、传输线几何尺寸(包括线宽,线高和介质厚度等)对传输特性的影响,并总结了硅基上单层RDL和多层RDL传输线的不同传输规律。另外,提出了一种优化的叠层结构和差分信号线结构,大大改善了硅基上互连结构的传输性能。     

直流磁控溅射法制备TiO2薄膜的研究

论术采用直流磁控溅射法制备TiO2薄膜的实验研究。研究了氧流量、基片温度对制备TiO2薄膜的影响,并测量了薄膜的晶相结构和表面形貌,结果表明制备出了具有锐钛矿晶体结构的TiO2薄膜．     

透明型白碳黑粉体比表面积的测定和计算

本文系统的讨论了用ST-03型表面与孔径测定仪测定透明型白碳黑比表面积．基于白碳黑粉体在低温和气体饱和蒸气压范围内的多分子吸附平衡,依据BET多层吸附原理,采用流动色谱法测定白碳黑对氮气的吸附量．利用图解法确定工作曲线的斜率和截距,测定其样品的比表面积．由BET吸附公式计算出透明型白碳黑的比表面积为315．64 m2／g．     

电化学脉冲腐蚀制备均匀发光多孔硅

采用脉冲腐蚀和直流电化学腐蚀两种方法制备多孔硅,对这两种方法制备的多孔硅样品进行了扫描电镜和荧光光谱测量,发现脉冲腐蚀制备的多孔硅样品比直流腐蚀制备的多孔硅样品表面均匀、硅丝或者硅柱的尺寸较小、发光强度大,而且发光峰位有明显.的蓝移现象.同时我们还发现多孔硅样品的尺寸越小其能带越宽,由此得出多孔硅样品的发光现象符合量子限域解释的多孔硅的发光机制.     

Functions and transport of silicon in plants

Silicon exerts beneficial effects on plant growth and production by alleviating both biotic and abiotic stresses including diseases, pests, lodging, drought, and nutrient imbalance. Recently, two genes (Lsi1 and Lsi2) encoding Si transporters have been identified from rice. Lsi1 (low silicon 1) belongs to a Nod26-like major intrinsic protein subfamily in aquaporin, while Lsi2 encodes a putative anion transporter. Lsi1 is localized on the distal side of both exodermis and endodermis in rice roots, while Lsi2 is localized on the proximal side of the same cells. Lsi1 shows influx transport activity for Si, while Lsi2 shows efflux transport activity. Therefore, Lsi1 is responsible for transport of Si from the external solution to the root cells, whereas Lsi2 is an efflux transporter responsible for the transport of Si from the root cells to the apoplast. Coupling of Lsi1 with Lsi2 is required for efficient uptake of Si in rice. Received 21 December 2007; received after revision 29 April 2008; accepted 15 May 2008