Ca/Zn-纳米羧甲基壳聚糖的光谱分析

以壳聚糖为原料,经羧甲基化、纳米化与Ca~(2+)、Zn~(2+)复合制备出纳米羧甲基壳聚糖含钙、锌复合物,采用红外光谱、X射线衍射光谱、扫描电镜等光学手段对样品进行结构表征,考察了复合物的凝血、止血性能。结果表明:纳米羧甲基壳聚糖结构中含有磷酸盐结构,Ca/Zn-纳米羧甲基壳聚糖结构中含有Ca~(2+)与Zn~(2+),Ca~(2+)和Zn~(2+)与纳米羧甲基壳聚糖成功复合;复合物的结晶性下降、溶解性提高、形貌均匀圆整,且凝血、止血时间明显缩短;Ca-纳米羧甲基壳聚糖比Zn-纳米羧甲基壳聚糖结构更稳定,凝血、止血效果更好。     

靶向分子羧甲基多糖与DNA作用机理研究

以溴化乙锭(EB)为荧光探针,结合紫外光谱法研究了壳聚糖、羧甲基壳聚糖、羧甲基纤维素与DNA的相互作用,药物分子与DNA作用程度可用作用常数D来表示,实验表明: 几种生物多糖与DNA分子的作用强弱顺序为: 壳聚糖＞羧甲基壳聚糖＞羧甲基纤维素;多糖主要以嵌插方式与DNA作用, 使EB-DNA荧光猝灭。     

羧甲基壳聚糖与铕、铽配合物的合成和配位机理研究

用羧甲基壳聚糖分别与硝酸铕和硝酸铽反应,制备了羧甲基壳聚糖-铕和羧甲基壳聚糖-铽稀土配合物。用红外光谱和X射线光电子能谱(XPS)等分析测试手段对配合物进行表征。对配合物配位机理进行了初步的研究,配合物中羧甲基壳聚糖中不仅羧基参与了配位,氨基上的N原子和羟基氧原子也参与了配位。     

羧甲基壳聚糖的合成和光谱研究

本文以壳聚糖为原料制备了 N,O-羧甲基壳聚糖 ,以 IR、1 H NMR及 1 3C NMR进行了结构表征。结果表明 ,取代度大小顺序为 :OH- 6 >OH- 3>- NH2 ,此样品对重金属离子具有较强吸附性     

叶酸-O-羧甲基壳聚糖的制备与光谱分析

壳聚糖经羧甲基化制备出的O-羧甲基壳聚糖,采用离子交联法与叶酸复合制备出叶酸-O-羧甲基壳聚糖复合物。通过红外光谱、X射线衍射光谱、扫描电镜等测试手段进行表征,探讨了叶酸、O-羧甲基壳聚糖的质量比对复合物结构及性能的影响,利用断尾取血法探究复合物的凝血、止血性能。结果显示,叶酸-O-羧甲基壳聚糖凝血、止血效果显著。当叶酸与O-羧甲基壳聚糖的质量比为2∶5时,二者基团的作用力最强,复合物结构最稳定,凝血、止血效果最好。     

CSC-P(AM-AA)重金属捕集絮凝剂的光谱表征及其对重金属去除研究

采用光聚合技术成功制备了羧甲基壳聚糖(CSC)、丙烯酰胺(AM)、丙烯酸(AA)的三元接枝共聚物,即壳聚糖基重金属捕集絮凝剂CSC-P(AM-AA)。为了证明接枝共聚产物的成功制备和表征其结构特征,采用红外光谱(IR)、X射线衍射(XRD)、差热-热重分析(TG-DSC)、扫描电镜(SEM)对其进行表征,结果表明成功制备出羧甲基壳聚糖的接枝共聚物CSC-P(AM-AA),且具有较好的溶解性;由于羧甲基壳聚糖的接枝改性使得CSC-P(AM-AA)具有与P(AM-AA)显著不同的结构特征。同时絮凝实验证明其具有较好的重金属螯合捕集效果,在pH为8、投加量为8 mg·L-1、转速为150 r·min-1时,CSC-P(AM-AA)对Cu2+的最佳去除率为87.0%。     

羧甲基壳聚糖对Eu^3＋离子吸附性能的研究

以壳聚糖为原料,在碱性条件下合成了羧甲基壳聚糖,考察了其对稀土离子Eu3 的吸附性能.讨论了时间,溶液的酸度、初始离子浓度、羧甲基取代度及离子强度对吸附性能的影响.发现羧甲基壳聚糖对Eu3 有较强的吸附性,吸附性满足Langmir等温式.     

改性羧甲基壳聚糖复合材料的制备、表征与研究

为了提高壳聚糖的水溶性及其止血方面的性能，将壳聚糖（CS）进行羧甲基化改性，并引入具有抗菌作用的Ag⁺和TiO₂，制备出羧甲基壳聚糖复合止血材料。首先，在壳聚糖中引入羧甲基，制得羧甲基壳聚糖（CMCS），之后向其中引入Ag⁺和TiO₂，分别制备出Ag⁺-CMCS、TiO₂-CMCS和Ag⁺-TiO₂-CMCS复合材料。然后，采用FTIR、XRD、SEM等手段对复合材料的结构进行表征。最后，对复合物的凝血、止血性能进行了测试。实验结果表明：改性后的羧甲基壳聚糖的IR图谱在3 423 cm^-1和1 380 cm^-1处出现了羧甲基壳聚糖钠盐的特征吸收峰。改性后的羧甲基壳聚糖在XRD图谱中表现出了金属晶态。CMCS的粒径为14.8 nm左右，Ag⁺粒径为143.5 nm左右，纳米TiO₂的粒径为267.2 nm左右，且三者分散的很均匀。Ag⁺-TiO₂-CMCS的凝血、止血效果要优于Ag⁺-CMCS和TiO₂-CMCS，同时Ag⁺-CMCS和TiO₂-CMCS的凝血、止血效果要优于CMCS。     

分光光度法研究插层膨润土对有机染料的脱色性能

以钠基膨润土为原料制备o-羧甲基壳聚糖插层膨润土,通过XRD、IR及SEM表征插层膨润土的表面性质及组织构造;用分光光度法分析插层膨润土对有机染料的脱色性能;同时探讨表面活性剂和o-羧甲基壳聚糖加料顺序、配比对脱色性能的影响。结果表明:当表面活性剂和o-羧甲基壳聚糖为2:1时,先加入表面活性剂反应一定时间再加入羧甲基壳聚糖所得的插层膨润土对亚甲基蓝和酸性蓝脱色性能最优,脱色率可达98.5%。     

O-羧甲基壳聚糖的制备及波谱分析

壳聚糖与氯乙酸在氢氧化钾-异丙醇介质中作用,制备O-羧甲基壳聚糖.研究了反应温度、壳聚糖与氯乙酸质量比、氢氧化钾与氯乙酸质量比对反应产物结构的影响.壳聚糖与氯乙酸、氢氧化钾与氯乙酸的质量比分别在2:1及2.3:1时,室温下反应5h可得到较高取代度的O-羧甲基壳聚糖.采用红外光谱扫描法及X光电子能谱分析法对产物结构进行了表征.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.     

Fiber Modal Index Measurements Based on Fiber Gratings

A novel method based on fiber gratings for measuring the effective indices of fiber modes is proposed. The effective index difference between the core mode and a cladding mode was obtained by analyzing the interference fringe of a pair of cascaded long-period fiber gratings. In order to extract the core mode index from the measured index difference, an index matching oil immersion method is proposed. By analyzing the interaction between the cladding mode and the oil applied on the cladding surface, the mode order and the effective index of the involved cladding mode might be calculated. Experimental results about the interference fringe shifts induced by the oil index and the oil-applied length are also presented.     

Optical Pulse Compression Schemes That Use Nonlinear Bragg Gratings

Nonlinear optical pulse compression of picosecond pulses typically requires long lengths of optical fiber and multiple components. Periodic structures, such as fiber Bragg gratings, are highly dispersive at wavelengths outside of the photonic bandgap. This implies that such gratings can be used as very short all-fiber compressors. In this paper a number of such compression schemes are reviewed involving uniform and nonuniform fiber Bragg gratings, relying on both soliton and nonsoliton compression principles. Experimental results supporting the corresponding underlying theory are also presented. Finally, an extension of one of the compression schemes is shown, which allows the generation of adjustable high-repetition rate soliton trains.