荧光法研究可可碱与牛血清白蛋白的相互作用

采用荧光光谱法研究了可可碱这种生物碱药物与牛血清白蛋白(BSA)分子间的相互结合反应.测定了可可碱与BSA反应的结合平衡常数K和结合位点数n.并用同步荧光光谱技术考察了可可碱对牛血清白蛋白构象的影响.证实了可可碱药物与牛血清白蛋白的相互结合作用为单一的静态猝灭过程.可可碱的加入对牛血清白蛋白的构象有影响.     

柠檬酸钠与牛血清白蛋白的相互作用

用荧光光谱法研究了柠檬酸钠与牛血清白蛋白( BSA)的作用机制.实验表明,柠檬酸钠对BSA具有荧光猝灭作用,其猝灭方式为静态猝灭,并求出了猝灭常数、结合常数及结合位点数.     

头孢噻肟钠和氯霉素与牛血清白蛋白相互作用的荧光光谱分析

在pH=7.40 Tris-HCl缓冲溶液中,应用荧光光谱法分别研究了298,303,308 K时,头孢噻肟钠(CTX)、氯霉素(CHL)对牛血清白蛋白(BSA)荧光的猝灭反应.结果表明:药物与BSA的结合稳定常数Ka随温度增加而降低,两种药物对BSA的荧光猝灭皆为静态猝灭过程.标记竞争实验表明CTX、CHL在BSA中...     

锌离子与牛血清白蛋白相互作用的研究

用荧光光谱法研究了锌离子(Zn2+)与牛血清白蛋白(BSA)的作用机制.实验表明,Zn2+对BSA具有荧光猝灭作用,其猝灭方式为静态猝灭.求出了猝灭常数、结合常数及结合位点数.利用同步荧光光谱研究了Zn2+对BSA分子荧光光谱的影响.     

L-半胱氨酸修饰的金纳米粒子与牛血清白蛋白相互作用的荧光光谱研究

采用荧光猝灭光谱和同步荧光光谱研究了L-半胱氨酸修饰的金纳米粒子(Cys-GNPs)与牛血清白蛋白(BSA)间的相互作用。根据荧光猝灭相关方程计算了Cys-GNPs与BSA相互作用的结合常数和结合位点数,探讨了其荧光猝灭机制为静态猝灭,并且根据热力学参数确定了二者间的作用力类型,推断出Cys-GNPs和BSA间主要靠疏水作用力结合。同步荧光光谱表明,二者的相互作用没有导致牛血清白蛋白的构象及色氨酸残基的微环境发生明显变化。     

顺式氰戊菊酯与牛血清白蛋白相互作用的荧光光谱研究

用荧光光谱法研究了在生理pH值条件下杀虫剂顺式氰戊菊酯与牛血清白蛋白(BSA)的相互作用.结果表明:顺式氰戊菊酯对BSA的荧光有较强的猝灭作用,该猝灭属于静态猝灭.根据猝灭结果求得了不同温度下顺式氰戊菊酯与牛血清白蛋白作用的结合位点数、结合常数及反应热力学参数,并据此推测了它们之间主要的相互作用力为疏水作用力.还用同步荧光光谱法探讨了顺式氰戊菊酯对BSA构象的影响.     

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。     

荧光光谱法研究黄芩苷与牛血清白蛋白的相互作用

在pH为7.40的T ris-HC l缓冲体系中,采用荧光光谱技术研究了黄芩苷与牛血清白蛋白（BSA）的相互作用。随着温度升高,黄芩苷与牛血清白蛋白的猝灭常数逐渐增大,表明黄芩苷对BSA的荧光猝灭为动态猝灭过程,由结合过程的热力学参数ΔH=51.708 kJ.m o-l 1〉0和ΔS=265.075J.m o-l 1.K-1〉0,推断黄芩苷与BSA之间主要靠疏水作用力相结合,生成自由能变（ΔG）为负值,表明黄芩苷与BSA的作用过程是一个自发过程;应用同步荧光光谱考察了黄芩苷对BSA构象的影响。     

番红花红T与牛血清白蛋白作用的光谱特性

用荧光光谱法研究了番红花红T与牛血清白蛋白(BSA)的结合反应.结果显示番红花红T对牛血清白蛋白的荧光有猝灭作用,其猝灭类型属于静态猝灭;得到了不同温度下的结合常数和结合位点数;利用Van't Hoff方程计算得到该猝灭反应的热力学参数,结果表明番红花红T主要以静电作用力与BSA相互作用;同步荧光光谱显示番红花红T对B...     

氨与牛血清白蛋白的相互作用

用荧光光谱法和紫外吸收光谱法研究了在生理pH值条件下氨与牛血清白蛋白(BSA)的相互作用,结果表明:氨对BSA的荧光有较强的猝灭作用,该猝灭属于同时具有动态猝灭和静态猝灭特征的联合猝灭,但以静态猝灭为主.根据猝灭结果求得了不同温度下氨与BSA相互作用的结合位点数、结合常数及反应热力学参数,并据此推测它们之间主要的相互作...     

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.