拉盖尔高斯涡旋光束的传输

针对拉盖尔高斯涡旋光束,推导了其传输后目标平面上光电场的解析表达式,理论研究表明,传输一段距离后, 对于拉盖尔高斯光束的光斑大小的描述,高斯光斑尺寸已经不再适用.如果采用光强最亮处的半径来表示目标平面上的光斑大小则比较方便. 除了传输中的衍射导致光束展宽以外, 横截面上光束的相位分布也发生了独特的变化. 等相位线由原来的射线转化为弧线,拓扑电荷数为正时,弧线朝顺时针方向弯曲,拓扑电荷数为负时,弧线朝逆时针方向弯曲. 关键词： 涡旋光束 传输 光斑尺寸 相位分布     

光纤回音壁模式激光产生长度的实验与理论研究

采用沿光纤轴向光抽运消逝场激励增益的方式,获得了沿光纤轴向较长范围的回音壁模式激光辐射.研究了这种激光器的激光产生长度与抽运能量间的关系.实验发现:当抽运能量刚超过激光产生阈值时,激光产生长度迅速增长;随抽运能量的继续增加,产生长度的增长趋势变缓;产生长度随抽运能量的变化关系决定于增益包层溶液的染料浓度和溶液折射率.根据抽运光沿光纤轴向以受抑全反射方式传播的物理特性,在抽运能量中引入了遵循比尔吸收定律的指数衰减函数,结合消逝场激励增益的回音壁模式激光理论,在分析系统增益和损耗的基础上由激光阈值条件推导出了 关键词： 回音壁模式 受抑全反射 消逝场 激光产生长度     

Al等离子体类锂伴线的布居机制分析及实验应用

基于K壳层稳态碰撞辐射模型的程序,详细分析Al等离子体类锂伴线的主要布居机制,分别给出1s2p^{2 2}P-1s²2p²P,1s2s2p(¹S)²P-1s²2s²S与1s2p^{2 2}D-1s²2p² 关键词： 碰撞辐射模型 类锂伴线 线强比 激光等离子体     

Relation between soil matrix potential changes and water conversion ratios during methane hydrate formation processes in loess

With a new apparatus designed and assembled by ourselves, the matrix potential of non-saturated loess was firstly measured and studied during methane hydrate formation processes. The experimental results showed that during two formation processes, the matrix potential changes of the loess all presented a good linear relationship with water conversion ratios. In addition, although it was well known that the secondary gas hydrate formation was easier than the initial, our experimental results showed that the initial hydrate formation efficiency in non-saturated loess was higher than that of the secondary.     

Solid state photopolymerization of acrylic acid at low temperature

Near‐infrared spectroscopy was used to investigate the kinetic characteristics of acrylic acid photopolymerized at ?70°C and room temperature, respectively. The obtained results showed that at ?70°C the double bond conversion increased with increase in the initiator's concentration. Addition of soft chain component polyethylene glycol 400 (PEG400) could lead to high conversion in the solid state, and then high final double bond conversion after post‐curing. The introduction of water at low temperature also contributed largely to the enhancement in the initial and final double bond conversion in solid state. SEM photographs showed that more pores came up in the cured films with the increase in the water content in the reaction system. The change in the photoinitiator concentration, amount of PEG400, and content of water had significant effect on samples cured at lower temperature than at room temperature under the same conditions. Different kinds of photoinitiators showed different contributions to the initial and final double bond conversion on photopolymerization of acrylic acid at low temperature. Significant post‐curing phenomena for photopolymerization of acrylic acid at low temperature could be observed as well. Copyright © 2009 John Wiley & Sons, Ltd.     

Triterpenoids from the Flowers of Salvia miltiorrhiza

A phytochemical investigation of the flowers of Salvia miltiorrhiza Bunge led to the isolation of two new oleanane‐ and ursane‐type triterpenoids, (3α)‐olean‐12‐ene‐3,23‐diol ( 1 ) and (3α)‐urs‐12‐ene‐3,23‐diol ( 2 ), as well as of four known triterpenoids. Their structures were elucidated on the basis of spectroscopic evidence, including 1D‐ and 2D‐NMR, HR‐MS, and the X‐ray analysis, and by comparison with literature data.     

Simultaneous detection of five antibiotics in milk by high-throughput suspension array technology

A new suspension array technology is proposed for the simultaneous quantitative determination of five antibiotics—tylosin, tetracycline, gentamicin, streptomycin, and chloramphenicol in milk. A novel treatment of milk samples for suspension array with diethyl ether was performed which greatly reduced the interference of the disturbing components in milk on the reaction results with no significant effect on detection sensitivity. Compared with using biotin labeled monoclonal antibody, using of secondary antibody-biotin make the detection sensitivity further improved. The minimum detectable concentration in samples of tylosin, tetracycline, gentamicin, streptomycin, and chloramphenicol were 0.3, 1.5, 4, 20, and 25 ng/ml, respectively, and the working ranges of samples were 6-400, 7-300, 8-200, 90-3000 and 70-8000 ng/ml, respectively. The mean recovery was 89.38-113.73% with a standard deviation within 16.62%. The suspension assay technology is powerful for the fast quantitative analysis of multi-antibiotics residue in milk.     

New dibenzocyclooctadiene lignans from the Kadsura ananosma

Fourteen new dibenzocyclooctadiene lignans, ananonins A-N (1-14), together with five known compounds, were isolated from the seeds of Kadsura ananosma. The structures and absolute configurations of 1-14 were established using a combination of MS, NMR, and CD techniques. The biological activity of these compounds was evaluated, and ananonin M (13) showed moderate neuroprotective effects in an in vitro assay.     

Bisleuconins A-D: a pair of epimeric ent-kauranoid dimers and two new asymmetric analogues isolated from Isodonleucophyllus

A phytochemical investigation of Isodon leucophyllus led to the isolation of four novel ent-kauranoid dimers: bisleuconins A-D (1-4), and one known compound, rabdoloxin A (5). It was interesting that the structures of bisleuconins A (1) and B (2) were elucidated as a pair of epimeric ent-kauranoid dimers with unique linkage pattern C-16→C-17′ to connect two monomers. Bisleuconins C (3) and D (4) were two new asymmetric ent-kauranoid dimers. A possible biogenetic pathway of 1 and 2 was also proposed.     

Electric-field response of discotic hexabenzocoronene (HBC) liquid crystals

A HBC derivative bearing six branched, space-demanding, alkyl side chains containing ether linkages has been synthesized and its thermotropic properties were investigated by polarization optical microscopy (POM) and differential scanning calorimetry (DSC). To our surprise, this molecule can respond to electric fields, and the influences of alternating current (AC) and directing current (DC) electric field on the assembly of this molecule in liquid crystal cells were discussed.