无皂高分子纳米胶乳粒子的制备与稳定

在微波辐照下,以过硫酸钾（KPS）为引发剂,丙酮水溶（质量比1：1）为分散介质,进行了苯乙烯（ST（和其它共聚单体：甲基丙烯酸甲酯（MMA）,甲基丙烯酸丁酯（BMA）,丙烯酸乙酯（EA）及顺丁烯二酸酐（BDA）的无皂乳液聚合,得到了稳定的纳米胶乳粒子,讨论了共聚单体的种类和浓度对粒子水化半径的影响。增加配方中亲水性单体含量,使引发反应中引发剂的消耗量增加,粒子表面电荷密度增大,同时亲水性增加,油水界面张力减少,粒子变得稳定,有利于小粒子的生成,粒子的大小随亲水性单体的含量呈曲线关系,曲线上有最低点。     

等离子体化学气相沉积氮化镓薄膜中的N2/TMG等离子体发射光谱分析

对电子回旋共振低温等离子体化学气相沉积工艺(ECR-PECVD)沉积GaN薄膜过程中的氮气和三甲基镓有机金属气体(TMG)混合气体等离子体发射光谱进行分析。结果表明TMG 在等离子体自加热条件下就发生离解,N₂/TMG混合气体ECR等离子体主要以Ga气体粒子和亚稳态氮分子为主。发射光谱特征谱线随微波功率变化分析表明：当微波功率高于400 W时,亚稳态氮分子浓度随着微波功率的增加而增加,而高激发态氮分子以及氮分子离子浓度却随着减少。     

沿面闪络流体模型电离参数粒子模拟确定方法

介绍了粒子模拟确定高功率微波介质沿面闪络击穿流体模型相关电离参数的方法.对粒子模拟方法 (包括带电粒子动力学方程、次级电子发射以及蒙特卡罗碰撞模型)和流体整体模型方法 (包括连续性方程和能量守恒方程)做了简介.基于自编的1D3V粒子模拟-蒙特卡罗碰撞程序给出了在高(低)气压、不同气体种类以及不同微波场强和微波频率下流体模型电离参数的粒子模拟结果,包括电离频率、击穿时间、平均电子能量、电子能量分布函数类型.研究结果表明:平均电子能量与电子能量分布函数类型关系不大;中低气压下,电子能量接近Maxwell分布,电子能量分布函数类型对电离参数几乎没有影响;中高气压下,电子能量分布函数类型对电离参数有重要影响,其依赖系数X趋于高阶形式.不同气体的电子能量分布函数类型不同,需要利用粒子模拟对电子能量分布函数类型进行标定.同时,电子能量分布函数依赖系数与微波场强和频率也有关系,其随微波场强增加而增大,随微波频率增加而减小.在给定考察范围(微波场强在7 MV/m以下,微波频率在40 GHz以内),中低气压下,平均电子能量随微波场强增加而迅速增大,电离频率随微波场强增加先增大后降低,平均电子能量随微波频率增加而降低,电离频率随微波频率增加先增加后降低;高气压下,平均电子能量随微波场强增加而缓慢增大,电离频率随微波场强增加而增大,微波频率对平均电子能量和电离频率影响不大.     

紫外光引发阳离子聚丙烯酰胺的红外光谱研究

以丙烯酰胺(AM)、 丙烯酰氧基乙基三甲基氯化铵(DAC)、 丙烯酸丁酯(BA)为单体,采用紫外光引发聚合制备阳离子聚丙烯酰胺P(AM-DAC-BA)。 采用紫外光谱和红外光谱研究其结构特征;分析AM,DAC,BA,P(AM-DAC-BA)的红外光谱中的典型红外振动频率的归属。 通过与单体红外光谱比较得出：由于聚合产物的对称性增加,聚合产物红外光谱更加简单。 P(AM-DAC-BA)的特性粘度随着光强、 BA含量、 光引发剂浓度、 光照时间的增加而增加。 选取AM,DAC,BA中的—CONH₂,—COOCH₂(CO), —COOCH₂—(C—O—C),—CH₂—N+(CH₃)₃基团吸收峰为特征吸收峰,随着光强、 BA含量的增加,特征峰面积增加;随着光引发剂浓度增加特征峰面积却呈现减少趋势;随着光照时间增加,峰面积是先减小后增加。 但不同P(AM-DAC-BA)在红外光谱上对应的特征吸收峰的峰型类似,特征峰位置基本一致。     

高纯硅低能粒子辐照E′色心形成动力学研究

考虑固有点缺陷形成E′色心的情况,建立了E′色心形成的动力学模型,得到了高纯硅低能粒子辐照E′色心浓度与辐照剂量的关系式.结果表明,在低辐照剂量下,E′色心浓度随剂量的变化呈线性增长;随着辐照剂量的增加,E′色心浓度随剂量的变化呈饱和趋势.如果进一步考虑E′色心和其他物质反应形成新的稳定结构,E′色心浓度随剂量的变化呈双指数关系,E′色心浓度随剂量的变化不再趋于饱和状态,而是偏离饱和状态.理论结果和实验结果很好地符合,说明建立的模型是有效的.     

紫外光引发合成阴离子聚丙烯酰胺及其表征

选择了三种单体：丙烯酰胺(AM)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)和丙烯酸(AA),在复合引发剂的作用下,紫外光照射共聚得到阴离子聚丙烯酰胺(APAM)。研究了单体配比、单体总质量分数以及引发剂浓度等因素对聚合反应的影响,以产物特性粘度为目标进行了制备条件的优化,并对聚合产物的紫外、红外、电镜等结构和热性能进行表征。结果表明,在单体配比为70∶10∶10、单体质量分数为40%、引发剂浓度0.20%、反应体系pH值为9.0以及光照60 min条件下,能够制得特性粘度为1.6×103 mL·g-1的阴离子聚丙烯酰胺。     

金刚石膜α粒子探测器的电学性能研究

从外加偏压、预辐照处理等方面对三明治结构金刚石膜探测器在α粒子辐照下的电学性能进行了研究.电流-电压特性和脉冲高度分布测试和分析表明，金刚石膜探测器在能量为5.5MeV的²⁴¹Am α粒子辐照一定时间后，其暗电流有所增加.探测器顶电极施加负偏压时，在α粒子辐照下得到的净电流和信噪比均较大.Raman光谱测试表明，造成上述现象的原因很可能是金刚石膜厚度方向的不均匀性分布.负偏压下探测器对α粒子的能量分辨率为25.0%，优于正偏压下的能量分辨率(38.4%).随着α粒子辐照时间的延长，探测器的净电流和电荷收集效率均有明显增加. 关键词： 金刚石薄膜 辐射探测器 电学性能 脉冲高度分布     

Sm_2Co_(17)型永磁合金的辐照效应研究

Sm_2Co_(17)型永磁合金大量使用在上海同步辐射光源储存环的永磁型波荡器上,在受到长期辐照后会发生磁性能损失的现象,进而影响同步辐射光的品质.为了探索其潜在的微观机理,本文首先对Sm_2Co_(17)型永磁合金所处混合辐射场的粒子及相关物理量进行了计算分析,确定引发磁性能损失的主要粒子是中子.然后采用Ar离子模拟中子辐照损伤的方法对其进行辐照,采用透射电镜对其辐照前后的微观形貌及微观结构进行了研究探讨,采用振动样品磁强计对永磁合金辐照前后的饱和磁化强度进行了分析对比,并讨论了微观结构演化与宏观磁性能变化的联系.结果表明,Ar离子辐照后Sm_2Co_(17)型永磁合金饱和磁化强度的不可逆损失与微观结构变化有直接的关系,其2:17相从单晶结构转变为非晶结构是造成其磁性能损失可能的微观机制.     

微波辐照下超导隧道电流公式

本文利用Keldysh与Larkin及Ovchinnikov等人发展的非平衡格林函数方法推导了在微波辐照下,超导隧道结的准粒子电流与Josephson电流公式,求得准确到微波场二次项的结果,并简要讨论了微波辐照的影响。     

紫外光辐射法表面接枝改性PET膜

用二苯甲酮(BP)做光引发剂,聚对苯二甲酸乙二醇酯(PET)薄膜用丙烯酸进行紫外光照表面接枝改性。丙烯酸接枝率随光照时间、单体浓度增加而增加,并随引发剂浓度的变化而变化.光照时间为1h,引发剂的浓度为5×10-3mol/L,丙烯酸浓度为6%(wt%)时,接枝效果最好.通过接枝反应,羧基(—COOH)被引入到PET膜表面,提高了PET膜的亲水性和碱性染料的可染性。     

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.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

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.