Conformation of curdlan as observed by tapping mode atomic force microscopy

Tapping mode atomic force microscopy was used to study the bacterial polysaccharide curdlan deposited from dimethyl sulfoxide (Me₂SO) and NaOH aqueous solutions. For curdlan in Me₂SO, flexible single chains corresponding to a disordered conformation were observed at a concentration of 5 mg/l, and the chain diameter was measured to be 0.65±0.05 nm, which showed good agreement with the expected value of the single polysaccharide chain. Because the concentration of curdlan increased, the chains became more rigid and aggregated, subsequently, the network structures of curdlan appeared. However, curdlan samples deposited from a 5 mM NaOH solution showed entirely different conformations. The chains observed were almost in the form of micelles of several nanometers, which were supermolecular assemblies. The heterogeneously dense zones were observed as the curdlan concentration increased to 40 mg/l. When the concentration of curdlan was above 100 mg/l, which might cause the real concentration of curdlan on the mica substrate after drying treatment exceeding some critical value of gelation, gel network structures were formed. Keeping on increasing the concentration of curdlan, the image showed a more homogeneous fibrous network.     

Simulations of rare events in fiber optics by interacting particle systems

In this paper we study the robustness of linear pulses, solitons, and dispersion-managed solitons, under the influence of random perturbations. First, we address the problem of the estimation of the outage probability due to polarization-mode dispersion. Second, we compare the pulse broadening due to random fluctuations of the group-velocity dispersion. We use an original interacting particle system to estimate the tails of the probability density functions of the pulse widths. A new adaptative Monte Carlo method is applied that enforces the simulations to probe the regions of practical importance by selection and mutation steps.     

Optimum and near optimum feature selection for multivariate data

In designing pattern classification systems for a small number of training samples, investigators have quoted that there exists an optimal number of features one can use. This number is a function of the number of training samples and the probability structure of the data. A recursive algorithm is given for selecting a near optimal feature set for classifying a data set consisting of two classes described by two equiprobable multivariate normal densities with a common covariance matrix. We compare this near optimal feature selection algorithm with the optimal exhaustive search algorithm and discuss examples for both algorithms.     

PMOLED发光特性的研究

为了研究PMOLED器件的物理特性。在Alq3主体材料中掺杂C545制备了PMOLED发光器件．其单象素结构为TO（120nm）／CuPc（12nm）／NPB（50nm）／Alq3：C545（30nm）／LiF（1nm）／Al（200nm），色坐标为（0．276，0．589）。该器件的载流予注入模型，在起亮前符合热发射注入模型；起亮后满足遂穿注入模型。PMOLED能较好地满足朗伯定律，并具有响应速度快，视角宽，色彩保真度高等特性。     

Mode selectivity of multisegment composite-cavity semiconductor lasers

The single longitudinal mode (SLM) characteristics of narrow linewidth long-external-cavity semiconductor lasers has been improved significantly by using a multisegment composite-cavity configuration. In this paper, the mode selectivities of two-segment, three-segment and four-segment cavity semiconductor lasers have been analysed and compared. In experiments, a four-segment composite cavity laser exhibits SLM oscillation with side-mode suppression ratio of 30 dB even for total external cavity length of 75 cm. The oscillation linewidth is less than 200 kHz.     

基于单片机的CPLD/FPGA被动串行下载配置的实现

介绍采用AT89S2051单片机配合串行E^2PROM存储器，实现CPLD／FPGA器件的被动串行模式的下载配置，阐述了其原理及软硬件设计。     

多束激光相位共轭偏振合成技术的实验研究

进行了多束激光相位共轭偏振合成研究。种子激光源使用的是Cr4 + ∶YAG被动调Q 的扭转模激光器,分束/ 合束是通过使用偏振片来实现,最终实现了三路激光的基于相位共轭的偏振合成,指标为重频10Hz ,脉冲能量150mJ ,脉宽4ns ,M2 为116。     

甲苯酚第一激发态的共振多光子电离谱

测量了间位甲苯酚和甲酚异构体混合物能量在３５１８０－３６００２ｃｍ＾－１范围的双光子共振四光子电离谱。对第一电子激发态振动带做了分析和归属，并对苯分子的不同取代对振动模的影响做了比较和分析。     

模糊传感器训练算法

本文提出了模糊传感器的一种分段式训练调参方法。对温度模糊传感器的仿真结果表明，该方法能在不同的测量结构下，较好地解决人类感知温度的模糊语言描述问题。     

宽带泵浦激光的聚焦位置对SRS发生过程的影响

 结合SRS实验,重点研究了聚焦位置对Raman介质中的物理过程、Stokes光的输出特性的影响,比较了SRS阈值和转换效率的实验结果与理论预期。