Ultrafine optical-frequency tunable Brillouin fiber laser based on fiber strain

We present an ultrafine tunable single-frequency Brillouin fiber laser in which the fiber Brillouin gain also acts as a high-precision tunable filter. Controlling the strain on the fiber, the Stokes frequency shift may be precisely changed, and thus the lasing frequency can be tuned. Assisted by the frequency pulling effect, this method provides continuous ultrafine tuning ability for ~30% of the free spectral range without mode hopping, and can cover 271 MHz. The experiments showed that the laser achieves tuning step of 60 kHz.     

1.5次微分吸附阴极溶出伏安法测定毛地黄毒苷及其电极过程的探讨

毛地黄毒苷是治疗心脏病的有效药物,它在汞电极上能吸附还原.以1.5次微分吸附阴极溶出伏安法测定检出限达3.2×10~(-10)mol/L.吸附溶出响应依赖于试液浓度、富集电位、富集时间、介质、溶液pH、温度及扫速等因素.不同富集时间,不同浓度范围内.浓度与峰高有良好的线性关系.毒苷的常规循环伏安图上出现两对氧化还原峰,电极反应相似于α,β不饱和羰基的1,2和1,4加成,电极反应可逆.毒苷在汞电极上的饱和吸附量为3.54×10~(-11)mol/cm~2.     

An Equivalent Form of the Dedekind Axiomand Its Application(Ⅱ)——Also on the unity of the Continuous Induction,the Mathem atical Induction and the Transfinite Induction

§１．　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅＣｏｎｔｉｎｕｏｕｓＩｎｄｕｃｔｉｏｎｏｆｒｅａｌｎｕｍｂｅｒｉｓｒｅｗｒｉｔｔｅｎａｓｂｅｌｏｗｉｎｔｈｉｓｐａｐｅｒ（Ⅰ）．ＴｈｅＣｏｎｔｉｎｕｏｕｓＩｎｄｕｃｔｉｏｎ（Ａ）：ＳｕｐｐｏｓｅｔｈａｔＰｘｉｓａｐｒｏｐｏｓｉｔｉｏｎｃｏｎｃｅｒｎｉｎｇａｒｅａｌｎｕｍｂｅｒｘ．Ｉｆｔｈｅｒｅｉｓｓｏｍｅｘ０ｓｕｃｈｔｈａｔＰｘｉｓｔｒｕｅｆｏｒｅｖｅｒｙｘ＜ｘ０，ｔｈｅｎＰｘｉｓｔｒｕｅｆｏｒｅｖｅｒｙｒｅａｌｎｕｍｂｅｒｘ．ＩｆＰｘｉｓｔｒｕｅｆｏｒｅ…     

SURFACE MODIFICATION AND DISPERSION OF NANODIAMOND IN CLEAN OIL

The effect of different kinds of surfactants on the size distribution of nanodiamond particles in clean oil was studied.Results show that the dispersing stability of nanodiamond modified with surfactangts YS-1 and SB-18 simulta-neously is much better than those modified with either of them because of synergism of the surfactangts.And the particle size distribution in the system can be improved remarkably after the adoption of hyperdispersants such as SA-E and SA-F.Anchoring groups of those hyperdispersants can be bonded with the particle surface by chemical and/or hydrogen bonding and their soluble chains are well compatible with the dispersion media.As a result,the particles are uniformly distrbuted in the system owing to the steric stabilization.A very stable clean-oil based nanodiamond suspension with an average particle size of around 53.2 nm was prepared.     

光学自由曲面数控化加工方法

在光学系统中，为了满足特殊的成像要求，需要使用自由曲面光学零件，但由于自由曲面是一类非常复杂的曲面，用传统的光学加工方法很难加工。本文概要介绍了光学非球面的多种加工方法，探索了这些方法加工光学自由曲面的可能性，提出了用数控化加工方法加工光学自由曲面，并利用这种方法加工了一块自由曲面透镜。     

Robust external cavity diode laser system with high frequency stability for Cs atomic clock

<正>A robust external cavity diode laser(ECDL) insensitive to mechanical vibration is built with an interference filter for selecting wavelength and a cat-eye reflector for light feedback.The free-running laser has a linewidth of 72 kHz.The laser frequency stability reaches 3×10~(-12) at 1-s integration time in terms of relative Allan variance based on the saturation absorption spectrum.     

Dual effects of dimethylsulfoxide on cellulose solvating ability of 1-allyl-3-methylimidazolium chloride

Polar aprotic solvents are considered to act as cosolvents with ionic liquids (ILs) for cellulose, strengthening the solvating ability of ILs by improving their cellulose solvating kinetics without influencing the solubility of cellulose in ILs. In this work, it was found that dimethylsulfoxide (DMSO) at low concentration improves the cellulose solvating ability of [AMIM][Cl], but weakens it at high concentration. To clarify the mechanism of these dual effects of DMSO on the cellulose solvating ability of [AMIM][Cl], the [AMIM][Cl]/DMSO system was investigated using excess infrared spectroscopy, nuclear magnetic resonance (NMR) T ₂ relaxometry, ¹H NMR, ³⁵Cl NMR, and dynamic light scattering. The results indicate that the tight association between the cation and anion in the [AMIM][Cl] network is loosened at low DMSO concentration. As a result, mass transport is accelerated due to the enhanced dynamics of [AMIM][Cl], promoting the cellulose solvating kinetics of [AMIM][Cl]. However, ion clusters of [AMIM][Cl] start to form when the molar fraction of DMSO (x _DMSO) exceeds 0.5. The hydrogen bonds between cations and anions in the ion clusters become much stronger than in pure [AMIM][Cl], leading to decreased ability of [AMIM][Cl] to form hydrogen bonds with cellulose and thus decreased cellulose solubility in the [AMIM][Cl]/DMSO mixture.     

54Xe^q＋（q=1,2）与H和He碰撞的电荷剥离截面

采用二体碰撞近似和托马斯－费米近似方法计算了多电荷离子５４Ｘｅｑ＋ （ｑ ＝ １,２ ）与中性原子Ｈ和Ｈｅ 碰撞的电荷剥离截面、电子动量分布和离子势函数分布。计算结果与平面波玻恩近似结果符合得较好     

A Chemo-enzymatic Route for the Preparation of Chiral （S）-3-Hydroxy-3-phenylpropanoic Acid

（S）-3-Hydroxy-3-phenylpropanoic acid is a potential progenitor of optically pure tomoxetine hydrochlo- ride and fluoxetine hydrochloride which are currently available antidepressant drugs. We report here the chemical synthesis of racemic substrate （R,S）-ethyl 3-hydroxy-3-phenylpropanoate and enzymatic preparation of S-isomer of the substrate by employing Porcine pancreas lipase（PPL） as a biocatalyst. Optimum enzyme-catalyzed reaction con- ditions, such as the effects of the temperature, pH and solvents on conversion degree and enantiomeric excess, were studied. An optimal temperature of 35 ℃ and pH=7.5 are the best for the resolution of （R,S）-ethyl 3-hydroxy-3- pheylpropanoate by PPL when 0.1 mol/L phosphate buffer solution acts as a medium. This work provides a practi- cally chemo-enzvmatic oreoaration of chiral β-hvdroxv acid by PPL.