荧光光谱法研究四(对甲氧基苯基)卟啉铅与牛血清白蛋白的相互作用

利用荧光光谱法研究了溶液pH值、溶剂种类和不同浓度的四(对甲氧基苯基)卟啉铅与牛血清白蛋白的相互作用,实验结果表明:四(对甲氧基苯基)卟啉铅对BSA有较强的静态荧光猝灭作用,按照Stern-Volmer方程和双倒数方程分析处理实验数据,得到反应的双分子猝灭过程速率常数Kq=1.0865×1013(L·mol-1·s-1)、结合常数KA=9.232×104L·mol-1、结合数n=0.7639.     

荧光法研究四(对甲氧基苯基)钴卟啉与牛血清白蛋白的相互作用

合成了四(对甲氧基苯基)钴卟啉,利用荧光光谱法研究了四(对甲氧基苯基)钴卟啉与牛血清白蛋白的相互作用,由实验数据计算求得该卟啉与牛血清白蛋白的双分子猝灭过程速率常数Kq=9.619×1012L·mol-1.s-1、结合常数KA=3.475×103L·mol-1、结合数n=0.6893,结果表明:四(对甲氧基苯基)钴卟啉与牛血清白蛋白之间发生了较强的静态荧光猝灭作用。     

番茄红素与牛血清白蛋白的相互作用

采用荧光光谱法研究了番茄红素(Lycopene)与牛血清白蛋白(BSA)的相互作用关系。研究表明,番茄红素能使BSA在340nm(λem)处产生荧光猝灭,猝灭机理为静态猝灭。pH=7.4,温度为293K时,猝灭时表观结合常数KA为5.33×104L.mol-1,结合位点数n为0.6461,同时荧光猝灭最大速率常数Kq=2.76×1012L.mol-1.s-1。二者呈自发结合且主要作用力为氢键和范德华力,结合距离r与能量转移效率E分别为5.6nm和0.098,偏酸性或碱性的条件使番茄红素与BSA的结合常数增加。     

阿维菌素与牛血清白蛋白作用的光谱研究

依据阿维菌素与牛血清白蛋白的结合作用使牛血清白蛋白内源荧光发生改变的现象,用荧光光度法研究了在一定条件下阿维菌素和牛血清白蛋白相互作用的机理。结果表明,阿维菌素对牛血清白蛋白的荧光猝灭是形成了超分子化合物的静态猝灭过程。测定了在不同温度下阿维菌素与牛血清白蛋白的结合常数KA和结合位点数n分别为KA=2.26×103L·mol-1,n=1.08(25℃);KA=1.35×103L·mol-1,n=1.05(35℃)。根据阿维菌素与牛血清白蛋白相互作用的热力学参数,确定了阿维菌素与牛血清白蛋白之间的作用力类型为氢键和范德华力;根据Foerster非辐射能量转移理论求得阿维菌素与牛血清白蛋白的结合距离为2.55nm。用同步荧光光谱确定阿维菌素影响了BSA微区的构象。     

小檗碱与人血清白蛋白的相互作用

利用紫外光谱和荧光光谱技术研究了中药有效成分小檗碱与人血清白蛋白(HSA)的相互作用机制。利用荧光猝灭反应测得它们之间结合常数K=1.168×105 L·mol-1,结合位点数n=5.26。依据Frster非辐射能量转移机制,测得供体-受体间结合距离R=3.44 nm和能量转移效率E=0.303。认为小檗碱在HSA的位置阻断了酪氨酸残基与色氨酸残基之间的能量转移,并使它们的荧光猝灭,并与色氨酸结合生成了较弱的荧光发光体。     

四(对甲氧基苯基)钐卟啉与牛血清白蛋白相互作用的研究

合成了四(对甲氧基苯基)钐卟啉,利用荧光光谱法研究了四(对甲氧基苯基)钐卟啉与牛血清白蛋白(BSA)的相互作用。结果表明四(对甲氧基苯基)钐卟啉对BSA的荧光有较强的猝灭作用,属于静态荧光猝灭,由实验数据求得猝灭速率常数K_q=1.3842×10~(13)L·mol~(-1)·s~(-1)、结合常数K_△=3.4610×10~4L·mol~(-1)、结合数n≈1。     

荧光光谱法研究四环素和牛血清蛋白的荧光猝灭和增敏作用

利用荧光光谱法研究了四环素和牛血清白蛋白(BSA)分子间的相互作用,在BSA荧光最强的pH=6.5的醋酸缓冲溶液中测定了结合常数(在19℃,7.61 ×103L·mol-1)和结合点数(n=0.88).研究表明:四环素可猝灭BSA的荧光,是静态猝灭过程.同时四环素的荧光也被BSA增敏并随着BSA的浓度的增加而增加.用同步扫描法讨论了四环素对BSA构象的影响和作用点位.     

秋水仙碱与人血清白蛋白相互作用的谱学研究

采用紫外、荧光和圆二色光谱研究了秋水仙碱与人血清白蛋白之间的相互作用。结果发现秋水仙碱使人血清白蛋白的紫外吸收增强,特征荧光峰猝灭,并且随温度升高猝灭常数K_SV降低。求算了不同温度下秋水仙碱与人血清白蛋白相互作用的平衡常数与结合位点数。根据Van’t Hoff方程计算出ΔH=-11.66 kJ·mol-1,ΔS=51.507 J·(mol·K)-１,得出二者之间的作用力主要是静电作用力。圆二色光谱测得加入秋水仙碱后人血清白蛋白的α-螺旋降低,二级结构改变,表明秋水仙碱对人血清白蛋白的荧光猝灭机制属于形成配合物所引起的静态猝灭。     

叶酸与人血清白蛋白结合作用的光谱研究

在不同温度下的pH 7.4的Tris-HCl缓冲溶液体系中, 采用荧光光谱、紫外吸收光谱和同步荧光光谱研究了人血清蛋白与叶酸的相互作用。研究表明,这种相互作用使人血清白蛋白发生内源荧光猝灭,属于静态猝灭机制。通过计算得到人血清蛋白与叶酸在17和37 ℃下静态猝灭的猝灭速率常数分别为7.396 6×104和7.2652×104 L·mol-1、结合常数分别为7.50×104和1.98×105 L·mol-1、结合位点数均为1。根据Förster非辐射能量转移机理,求算出给体(HSA)与受体(叶酸)间的作用距离和能量转移效率分别为1.77和0.052 65 nm,并结合热力学参数说明了叶酸分子与人血清白蛋白的作用以疏水作用为主,同时也存在静电引力。利用同步荧光光谱研究了人血清蛋白与叶酸的相互作用中HSA的构象变化,发现色氨酸残基所处环境的疏水性降低,说明叶酸分子进入了人血清白蛋白的疏水腔中。     

荧光法研究左氧氟沙星与人血清白蛋白作用机理及含量测定

利用荧光及紫外光谱法研究了水溶液体系中左氧氟沙星(LVFX)与人血清白蛋白(HSA)的相互作用机制.结果表明左氧氟沙星对人血清白蛋白的荧光有较强的猝灭作用,其猝灭类型主要为静态猝灭.在不同温度下求得了左氧氟沙星与人血清白蛋白的结合常数k.发现随反应温度上升k值下降.由热力学参数.确定了左氧氟沙星与人血清白蛋白的结合作用主要为色散力.用同步荧光技术考察了左氧氟沙星对人血清白蛋白构象的影响.又根据Foerster理论,测得了左氧氟沙星与入血清白蛋白结合的能量转移效率.相互结合距离.进一步证明了该反应是单一静态猝灭过程.阐述了其猝灭机理是通过能量转移产生的.研究发现人血清白蛋白荧光猝灭程度的对数与左氧氟沙星含量有良好的线性关系,25 C时线性范围为:2.O×10-6-2.4×10-5mol·L-1,检出限为1.2×10-7mol·L-1.用于片剂中左氧氟沙星含量的测定结果满意,相对标准偏差为:1.5%-2.1%,回收率为:94.8%-97.7%.     

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.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.     

An effective method for reducing speckle noise in digital holography

An effective method for reducing the speckle noise in digital holography is proposed in this paper.Different from the methods based on classical filtering technique,it utilizes the multiple holograms which are generated by rotating the illuminating light continuously.The intensity images reconstructed by a series of holograms generated by rotating the illuminating light possess different speckle patterns.Hence by properly averaging the reconstructed intensity fields,the speckle noises can be reduced greatly.Experimental results show that the proposed method is simple and effective to reduce speckle noise in digital holography.     

Influence of purity of HfO2 on reflectance of ultraviolet multilayer

The impurities in two kinds of HfO2 materials and in their corresponding single layer thin films were determined through glow discharge mass spectrum technology and secondary ion mass spectrometry(SIMS) equipment respectively.It was found that ZrO2 was the main impurity in the two kinds of HfO2 either in the original HfO2 materials or in the electron beam deposited films.In addition,the difference of Zr content in the two kinds of HfO2 single laver films was much laxger than that of the other impurities such as Ti and Fe.which showed that it was just ZrO2 that made the difference between the optical performance of the film products including the two kinds of HfO2.With these two kinds of HfO2 and the same kind of SiO2.we deposited HfO2/SiO2 multilayer reflective coatings at the wavelength of 266 nm.Experimental results showed that the reflectances of these two mirrors were about 99.85% and 99.15% respectively,which agreed well with the designed results what were based on the optical constants obtained from the corresponding single layer thin films.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.