β-环糊精衍生物对昔康类药物的增溶作用

相溶解度法研究了吡罗昔康、美洛昔康和氯诺昔康与β-环糊精(β-CD)、磺丁醚-β-环糊精(SBE-β-CD)和羟丙基β-环糊精(HP-βCD)的包合特性.结果表明,昔康类药物与3种环糊精都形成了1:1的包合物.环糊精包合能力HP-β-CD>SBE-β-CD>β-CD.增溶效应氯诺昔康>美洛昔康>吡罗昔康.     

若丹明B掺杂的SiO2凝胶的荧光光谱研究

以正硅酸乙酯（TEOS）和有机染料若丹明B（Rhodamine B)为原料，彩溶胶－凝胶方法（the sol-gel method)制备了若丹明B掺杂的SiO2凝胶，研究了SiO2凝胶的荧光光谱。报道了若丹明B在SiO2凝胶中的荧光光谱比在水中的荧光光谱发生红移，尤其在制备过程中的不同阶段，若丹明B掺杂SiO2凝胶的荧光光谱的峰位发生的一系列变化，从而得到了若丹明B在水中及若丹明B在SiO2凝胶制备过程之中，直至SiO2凝胶制备完毕的荧光光谱发生变化的全过程。还报道了在反应中的磁力搅抖阶段，采用回流过程和不采用回流过程两种方法时，对所得若丹明B掺杂SiO2凝胶的荧光光谱的影响。     

氧化硅气凝胶的超临界制备及纳米结构

简要介绍了用溶胶－凝胶法制备新型功能材料氧化硅气凝胶的方法，着重阐述了氧化硅气凝胶的各种干燥过程对其纳米结构的影响，说明了超临界干燥工艺在保持气凝胶的纳米多孔结构方面的突出重要地位，同时，用比表面积测量，扫描电镜，小角Ｘ射线菜射等研究了这种轻质纳米多孔非晶固态材料的结构特性，介绍了这种材料的应用前景。     

分散剂对RF凝胶掺钛过程的影响

 以间苯二酚、甲醛和经分散的纳米钛粉为反应前体，利用物理掺杂方法研究了掺钛RF凝胶的制备工艺，并在凝胶过程中以zeta电位 粒径分布测试仪对溶液的粒径分布进行分析测试。实验发现六偏磷酸钠对纳米钛粉的分散性最好，掺杂后凝胶时间明显缩短；分散剂种类和用量对凝胶时间有较大影响，其用量为纳米钛粉量的50~100倍为宜。     

有机染料DI在不同的凝胶体系中的光谱特性

分别以正硅酸乙酯（ＴＥＯＳ）和有机改性硅酸盐ＫＨ５６０－ＫＨ５５０凝胶体系为基质，为用溶胶－凝胶工艺，成功地将有机染料ＤＩ到上述基质中，通过对染料ＤＩ在不同凝胶材料中的孔结构分析，吸收光谱以及荧光光谱方法的分析，发现以ＫＨ５６０－ＫＨ５５０凝胶体系为基质的材料对染料的光学性质更为有利。     

小角x射线散射法研究甲基改性氧化硅凝胶的双分形结构

以正硅酸乙酯［Si(OC2H5)4,TEOS］和甲基三乙氧基硅烷［CH3Si(OC2H5)3,MTES］为前驱体，通过共水解法和两步法制备出两种不同的甲基改性氧化硅凝胶，在北京同步辐射光源(BSRF)小角x射线散射(SAXS)站测量了凝胶的散射强度，计算了凝胶的平均粒径、两相间比表面积等参数，在此基础上分析了凝胶的分形特征，发现存在两个尺度上的分形结构，分别对应于从SiO2原生颗粒到一次团聚体和从一次团聚体到簇团两种尺度.辅以透射电子显微镜(TEM)观测，证实由两种方法获得的凝胶具有非常不同的微观结构.实验证明，利用SAXS技术研究甲基改性凝胶的分形特征是获得凝胶微观结构的有力工具. 关键词： 甲基改性凝胶 氧化硅 小角x射线散射(SAXS) 分形结构     

微米手性晶粒凝胶玻璃的制备及其消偏振效应

采用干法粉碎法将具有手性特征的块体水晶粉碎成粒径为70μm的手性晶粒，利用溶胶-凝胶法，将粒径为70μm的手性晶粒均匀地撒入凝胶基质中，制成厚度为4mm的含微米手性晶粒的凝胶玻璃，发现其表现出了消偏振效应.而将微米手性晶粒替换成同样尺寸粒径的玻璃粉体，以同样方法制成的相同厚度的含微米玻璃粉体的凝胶玻璃却表现出线偏振保持的性能.分析了此现象发生的原因. 关键词： 手性晶粒 溶胶-凝胶 消偏振     

制备条件对气凝胶粉末粒径的影响

 利用超声波乳化技术，结合溶胶-凝胶反应制备了间苯二酚-甲醛有机气凝胶粉末和碳化气凝胶粉末。通过大量实验，探讨了制备条件对气凝胶粉末粒径的影响。在粉末干燥前以Zeta电位-粒径分布测试仪对乙醇悬浊液进行分析测试，对有机粉末和碳化粉末用TEM方法进行表征。研究了反应液质量分数、反应温度和时间以及分散剂与反应液体积比对产物粒径的影响。实验表明：制备条件对于制备纳米级的气凝胶粉末影响非常大，通过优化实验条件可以制备出分布较好的气凝胶粉末，超声功率较大容易实现体系均匀混合，反应液在反应过程中温度和时间的控制起着关键的作用，低质量分数的反应液所生成的产物比高质量分数的粒径要小,经碳化后粉末粒径进一步降低。     

分子链缠结对核-壳结构复合凝胶非均匀变形行为的影响

凝胶分子形成凝胶网络时，分子链段间会相互缠绕形成物理交联，显著影响其力学行为.为研究凝胶分子链段间相互缠结形成的物理交联对核壳结构复合凝胶变形行为与溶剂分布的影响，基于slip-link链缠结模型和张量推导建立核壳结构复合凝胶变形过程的一般数学表达式.结果表明：受刚性核影响，凝胶壳的拉伸是各向异性的，凝胶壳内溶剂的分布也是非均匀的，由内向外呈非线性变化，溶剂在凝胶内的扩散不满足菲克扩散定律；分子链缠结度越高凝胶壳的径向和周向伸长比越低，凝胶的溶胀率也越低.     

三聚氰胺-甲醛系凝胶老化过程中的体积收缩影响因素

 介绍了三聚氰胺-甲醛凝胶老化过程的溶剂效应及其对体积收缩的影响。从凝胶的离浆-溶胀平衡以及溶剂效应等两个方面对湿凝胶老化过程中的体积收缩作了分析，通过测量形状规则的湿凝胶在溶剂交换和老化过程中的体积变化研究湿凝胶组成、交换溶剂的成分及步骤对凝胶体积收缩的影响。结果表明：控制交换溶剂的组成能显著改善湿凝胶后处理过程中的体积收缩。合适的湿凝胶交换步骤是先使用凝胶体内液体和目标溶剂的混合溶剂进行交换，逐次增大目标溶剂的含量，直至最后使用纯目标溶剂进行交换，即可获得体积收缩较小的湿凝胶体系。     

Spectroscopic studies of microenvironment dictated structural forms of piroxicam and meloxicam

Long acting non-steroidal anti-inflammatory drugs (NSAIDs) belonging to the oxicam group have attracted special interest because of their diverse biological functions. In this study we present the influence of microenvironment on the spectral properties of two oxicam drugs viz. piroxicam and meloxicam. For the two drugs, a high energy shift of the UV absorption maxima was observed with increasing drug concentrations both in protic solvent like ethanol and aprotic solvent like dimethyl sulfoxide (DMSO). Studies involving variation of percentage volume of water as well as pH, using absorption and steady state fluorescence spectroscopy, allow us to identify the principal species present at different concentrations of the drugs. It is found that even trace quantity of water present in the solvent becomes significant at low concentration of the drug making the water/drug ratio sufficiently large to support the formation of anion. As the concentration of the drug increases, the number of water molecules available per drug molecule decreases and most of the drug molecules face a relatively apolar environment in which zwitterionic/neutral species become predominant. This results in a concentration-dependent high-energy shift of the absorption maximum. This study demonstrates how microenvironments of these drugs guide the nature of the predominant form present in solution.     

Ultrasound influence on the solubility of solid dispersions prepared for a poorly soluble drug

Solid dispersions have been successfully used to enhance the solubility of several poorly water soluble drugs. Solid dispersions are produced by melting hydrophilic carriers and mixing in the poorly water soluble drug. Supersaturation is obtained by quickly cooling the mixture until it solidifies, thereby entrapping the drug. The effects of using ultrasound to homogenize the molten carrier and drug mixture were studied. In particular, the increase in drug solubility for the resulting solid dispersions was analyzed. Piroxicam, which has very low water solubility, was used as a model drug. A full factorial design was used to analyze how sonication parameters affected the solubility and in vitro release of the drug. The results show that the use of ultrasound can significantly increase the solubility and dissolution rate of the piroxicam solid dispersion. Pure piroxicam presented a solubility of 13.3 μg/mL. A maximum fourfold increase in solubility, reaching 53.8 μg/mL, was observed for a solid dispersion sonicated at 19 kHz for 10 min and 475 W. The in vitro dissolution rate test showed the sonicated solid dispersion reached a maximum rate of 18%/min, a sixfold increase over the piroxicam rate of 2.9%/min. Further solid state characterization by thermal, X-ray diffraction and Fourier transform infrared analyses also showed that the sonication process, in the described conditions, did not adversely alter the drug or significantly change its polymorphic form. Ultrasound is therefore an interesting technique to homogenize drug/carrier mixtures with the objective of increasing the solubility of drugs with poor water solubility.     

Template occluded SBA-15: An effective dissolution enhancer for poorly water-soluble drug

The aim of the present work was to improve the dissolution rate of piroxicam by inclusion into template occluded SBA-15. Our strategy involves directly introducing piroxicam into as-prepared SBA-15 occluded with P123 (EO₂₀PO₇₀EO₂₀) by self assembling method in acetonitrile/methylene chloride mixture solution. Ultraviolet spectrometry experiment and thermogravimetric analysis-differential scanning calorimetry (TG-DSC) profiles show that the piroxicam and P123 contents in the inclusion compound are 12 wt% and 28 wt%, respectively. X-ray powder diffraction and DSC analysis reveal that the included piroxicam is arranged in amorphous form. N₂ adsorption-desorption experiment indicates that the piroxicam has been introduced to the mesopores instead of precipitating at the outside of the silica material. The inclusion compound was submitted to in vitro dissolution tests, the results show that the piroxicam dissolve from template occluded inclusion compound more rapidly, than these from the piroxicam crystalline and template removed samples in all tested conditions. Thus a facile method to improve the dissolution rate of poorly water-soluble drug was established, and this discovery opens a new avenue for the utilization of templates used for the synthesis of mesoporous materials.     

Vibrational Spectrum of a Platinum Complex of Piroxicam

The infrared and Raman spectra of a platinum complex of the antiinflammatory drug piroxicam (Pir) and dimethylsulfoxide (DMSO) of composition [PtCl₂Pir(DMSO)] were recorded and briefly discussed on the basis of its structural characteristics. The metal-to-ligand vibrations are analyzed in detail.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.