注入Si中的稀土离子Er3+的光学特性

用离子注入方法,将稀土离子Er3+注入到n-Si单晶中,通过对其低温(77K)光致发光光谱的测量,研究其光学特性.结果表明,注入剂量控制在1×1012cm-2～1×1015cm-2范围,退火温度控制在900℃～1100℃时,样品的主要发光峰值位于1.54μm左右.研究了样品的光致发光光谱随注入剂量、退火温度的变化关系,给出峰值在1.54μm附近的未分辨开的谱线的半宽为16.4meV.     

Traveling－Wave Electrooptical Modulator on Polymeric Film with Reversal Poling Structure

Ｔｒａｖｅｌｉｎｇ－ＷａｖｅＥｌｅｃｔｒｏｏｐｔｉｃａｌＭｏｄｕｌａｔｏｒｏｎＰｏｌｙｍｅｒｉｃＦｉｌｍｗｉｔｈＲｅｖｅｒｓａｌＰｏｌｉｎｇＳｔｒｕｃｔｕｒｅ￥ＺＨＯＵＹｉ；ＣＨＥＮＹｉｘｉｎ（ＤｅｐａｒｔｍｅｎｔｏｆＡｐｐｌｉｅｄＰｈｙｓｉｃｓ，Ｓ...     

耐盐吸附树脂对增塑剂DIBP生产废水预处理的研究

采用耐盐吸附树脂NDA-66预处理增塑剂DIBP生产废水,研究了不同吸附剂对DIBP生产废水中主要污染物邻苯二甲酸的吸附脱附效果。实验结果表明,5种吸附剂中,NDA-66树脂对邻苯二甲酸处理效果最好,且符合Freundlich方程和Langmuir方程;动态吸附脱附过程中,单柱吸附量为7BV,最佳流速为1.5BV/h,最佳脱附剂为1BV 8%Na OH+2BV蒸馏水,温度为328K,脱附率能达到99%以上;放大实验过程中,NDA-66耐盐吸附树脂对增塑剂DIBP生产废水中邻苯二甲酸吸附稳定性较好。     

Glucose Biosensor Using Glucose Oxidase and Electrospun Mn2O3‐Ag Nanofibers

The highly porous Mn₂O₃‐Ag nanofibers were fabricated by a facile two‐step procedure (electrospinning and calcination). The structure and composition of the Mn₂O₃‐Ag nanofibers were characterized by SEM, TEM, XRD, EDX and SAED. The as‐prepared Mn₂O₃‐Ag nanofibers were then employed as the immobilization matrix for glucose oxidase (GOD) to construct an amperometric glucose biosensor. The biosensor shows fast response to glucose, high sensitivity (40.60 µA mM^?1 cm^?2), low detection limit (1.73 µM at S/N=3), low K_m,app value and excellent selectivity. These results indicate that the novel Mn₂O₃‐Ag nanfibers‐GOD composite has great potential application in oxygen‐reduction based glucose biosensing.     

Enantioselective Morita-Baylis-Hillman reaction promoted by L-threonine-derived phosphine-thiourea catalysts

A series of bifunctional phosphine-thiourea organic catalysts based on natural amino acid scaffolds were designed and prepared. L-threonine-derived bifunctional phosphine catalysts were found to be very efficient in promoting asymmetric Morita-Baylis-Hillman (MBH) reaction of acrylates with aromatic aldehydes, affording the desired MBH adducts with up to 90% ee. To gain mechanistic insights into the reaction, the effects of adding various additives on the MBH reaction were investigated. We propose that the hydrogen bonding interactions between the thiourea moiety of the catalyst and the enolate intermediate are crucial for the stereochemical outcome of the reaction. The method described in this report may provide a practical solution to the enantioselective MBH reaction of simple acrylates.     

Systematic screening of protein modifications in four kinases using affinity enrichment and mass spectrometry analysis with unrestrictive sequence alignment

Protein kinases transfer phosphate groups from ATP to substrate proteins, they are known to be involved in diverse cellular processes. They are also important therapeutic targets in pharmaceutical design. Previous studies indicated that multiple post-translational modifications (PTMs) exist in kinases in addition to phosphorylation, and these PTMs play an important role in regulating kinases activities. Nevertheless, a comprehensive analysis for PTMs of kinases is insufficient due to technical limitations, which prevent us from better understanding their functional regulation. Here, we have developed a novel strategy that combines glutathione S-transferase tag affinity enrichment with nano-liquid chromatography coupled with tandem mass spectrometry analysis and non-restrictive protein sequence alignment for identification of diverse PTMs in four yeast kinases. The method allows us to enrich and analyze the entire protein isomers and to minimize the loss of all isomers of protein sample during protein purification. In our study, nineteen phosphorylation sites and several other types of PTMs sites were localized in 4 protein kinases. In addition, we found that some interesting mass shifts can not match those of the known PTMs. It suggested the existence of some undescribed PTMs in the proteins. Accordingly, this study showed that the novel strategy holds a great potential for identification of full-spectrum PTMs in proteins. Our data serves as a stepping stone for future functional studies.     

The MacLaurin expansion for a G/G/1 queue with Markov-modulated arrivals and services

Consider a Markov-modulated G/G/1 queueing system in which the arrival and the service mechanisms are controlled by an underlying Markov chain. The classical approaches to the waiting time of this type of queueing system have severe computational difficulties. In this paper, we develop a numerical algorithm to calculate the moments of the waiting time based on Gong and Hu's idea. Our numerical results show that the algorithm is powerful. A matrix recursive equation for the moments of the waiting time is also given under certain conditions.     

AFM-tip-induced crystallization of poly(ethylene oxide) melt droplets

The AFM-tip-induced crystallization of poly(ethylene oxide) (PEO) melt droplets was studied. The melt droplets with a height of 50–100 nm and a lateral size of 2–3 μm were obtained by melting the PEO ultra-thin films on a mica surface. For the PEO samples with average molecular weights (M _n) ranging from 1.0 × 10³ g/mol to 1.0 × 10⁴ g/mol, the lateral perturbation from the AFM tip in the hard-tapping or nanoscratch modes could not induce the growth of the flat-on lamellae. In contrast, under AFM nanoindentation mode, the tip-induced crystallization occurred when a sufficiently high vertical tip force was applied to the melt droplets of PEO with M _n ⩾ 1.0 × 10⁴ g/mol. Moreover, the experimental results indicated that the AFM-tip-induced crystallization of PEO in the nanoindentation process had molecular weight dependence. Translated from Acta Polymerica Sinica, 2006, (4): 553–556 (in Chinese)     

丙氨酸咪唑钐的三维荧光激发和发射光谱

测量了新制丙氨酸咪唑钐水溶液的三维荧光激发和发射光谱,分析了在不同波长激发光作用下的荧光特征,与配体咪唑、α-丙氨酸及氯化钐的荧光谱进行了比较,讨论了模型化合物上转换荧光中的双光子和多光子加合现象并发现在10^-2-10^-4 mol/L 浓度范围内荧光强度与溶液浓度呈正相关.