Highly photostable distributed-feedback polymer waveguide blue laser using spirobifluorene derivatives

In this study, we synthesized the new spirobifluorene derivatives; hexylbiphenyl-spirobifluorene (HBP-Spiro) and triphenylamine-spirobifluorene (TPA-Spiro) and demonstrated the operation of a distributed-feedback polymer waveguide blue laser. In addition, we investigated the optical and lasing properties of spirobifluorene derivatives including photostability. The experimental slope efficiency and the energy threshold of a HBP-Spiro-doped waveguide laser were 3.6% and 1.9 μJ, respectively. An operation lifetime of 27,000 shots was obtained for a pump-pulse duration of 1.2 ns and energy of 3.0 μJ at a wavelength of 355 nm.     

Noninvasive subsurface analysis using multiple miniaturized Raman probes, part I: basic study of thin-layered transparent models of biomedical tissues

This study describes a basic theory for reconstructing pure Raman signals of materials composing a multilayer sample from Raman spectra obtained using two types of miniaturized Raman probes. An illustrative example is demonstrated using a multilayer system of samples composed of the transparent plastics polymethylmethacrylate (PMMA) and polyethylene (PE) as a model of thin-layered biomedical tissues. When the same region of an object is measured using Raman probes with different focal properties, the Raman spectra provide different depth profile information depending on the level of light penetration. Thus, a detailed comparison of the spectra can provide an interesting opportunity to probe the differences between the layers. A simple analytic form is presented for reconstructing the pure Raman spectra of the embedded layer. The method applies an understanding of the Raman sampling volume in layered transparent materials to the interpretation of Raman spectra experimentally measured by multiple probes. The basic theory described here is necessary for the expansion of the technique to turbid media, such as biological samples, where light-scattering effects must be considered. The potential applications of the proposed method include material and catalyst subsurface probing through different embedded materials, such as assessment of silicon wafers, effective noninvasive screening for catalyst synthesis, and biomedical tissue research.     

Radiation induced synthesis of Au-Pd nanoparticles of random alloy structure supported on carbon particles using the high energy electron beam

Au-Pd bimetallic nanoparticles supported on carbon particles were synthesized by reduction of precursor ions in an aqueous solution irradiated with a high energy electron beam. The composition of the samples was analyzed by the inductively coupled plasma atomic emission spectrometry (ICP-AES), and the morphology of the samples was observed by the transmission electron microscope (TEM). TEM micrographs indicated that Au-Pd particles of ca. 5-nm were well dispersed on the surface of carbon particles of ca. 30-nm without any serious agglomeration. Addition of citric acid to the initial solution and high pH were found to be effective for formation of random alloy structure in the resultant bimetallic nanoparticles. The change in the bimetallic structure from core-shell to random alloy was identified by techniques of the X-ray diffraction (XRD) and the extended X-ray absorption fine structure (EXAFS).     

旋转陶瓷片约束TIG电弧形态分析

收缩电弧是提高TIG电弧的能量密度的有效途径.提出一种新的约束TIG电弧方法,用两片平行旋转的陶瓷片,对电极附近的电弧进行约束.通过电弧形态的观察分析,以及焊缝形状的测量,试验研究了不同旋转陶瓷片约束条件下电弧的形态和加热特性.结果表明,旋转陶瓷片可以有效地对TIG电弧进行非轴对称约束.在垂直于陶瓷片旋转平面的方向上,电弧中心的载流区域稳定收缩.两陶瓷片之间距离的减小,电弧进入陶瓷片深度的增加,都会使电弧中心载流区的宽度减小,从而使焊缝的熔深增加.同时发现,随电弧受约束程度的增加,电弧电压略有上升.     

适用于复杂场景的多目标跟踪算法

在视觉目标跟踪应用中,传统算法在光照变化、阴影、遮挡和背景运动等复杂环境下面临着鲁棒性较差的问题。针对上述问题,首先在局部二进制类型(LBP)背景模型基础上,提出了自适应像素距离阈值编码的背景模型(ST-LBSP)克服阴影和光照变化对目标检测的影响;其次,为了克服遮挡、背景运动等问题,计算图像块之间的最小像素距离和图像块和目标历史数据之间的标准化差值平方和距离,依据距离信息对图像块进行整合;同时,对整合后的图像块,计算其光流矢量、区域内差异性和区域间差异性,对图像块进行分割;最后,采用结构化的支持向量机设计多目标跟踪器,实现了鲁棒的视觉跟踪。基于标准数据集的实验结果显示,该方法具有较强的鲁棒性和较高的跟踪精度。     

基于红外遥感信息的煤矿车辆 异常行为检测研究

为了提升煤矿车辆异常行为检测水平,设计了基于红外遥感信息的煤矿车辆异常行为检测方法。该方法引入清晰度权重以及拉伸系数实现红外遥感图像中目标煤矿车辆部位的局部增强,利用均值漂移算法跟踪增强后的红外遥感图像中目标煤矿车辆,依据煤矿车辆跟踪结果提取煤矿车辆运动方向、运动速度以及运动方向3项异常行为检测参数,采用加权融合方法处理煤矿车辆异常行为检测参数的状态函数,融合结果高于所设定阈值时,煤矿车辆存在异常行为,否则煤矿车辆为正常行驶状态。实验结果表明,该方法可利用煤矿车辆位置、车辆行驶速度以及车辆方向变化检测煤矿车辆异常行为,具有较高的应用性。     

电阻率比检测碱矿渣混凝土收缩性能可行性探讨

使用简易电阻测试法测试并计算碱矿渣混凝土不同深度的电阻率比,然后使用千分表法测试不同水胶比碱矿渣混凝土的收缩性能,并使用质量法测试同条件下碱矿渣混凝土的质量损失.建立了碱矿渣混凝土质量损失与干燥收缩之间的线性关系,探寻了碱矿渣混凝土电阻率比与质量损失之间的关系.结果表明:碱矿渣混凝土质量损失与干燥收缩之间的相关系数R2大于0.890 9,且拟合曲线的斜率与碱矿渣混凝土水胶比相关性较大;碱矿渣混凝土的电阻率比对其质量损失十分敏感,且呈正相关,因此可通过监测碱矿渣混凝土的电阻率比来评价其干燥收缩性能.     

施工工艺对水泥基轻质材料性能的影响研究

建筑回填领域出现了一种水泥基轻质材料,该材料因其独特性能而受到广泛关注。本文围绕不同施工工艺对水泥基轻质材料的影响展开研究,阐述水泥基轻质材料两种不同的施工工艺,研究不同施工工艺制备的试件抗压强度、收缩率和体积密度随养护龄期的变化趋势,并探索适宜的检测方法。结果表明,水泥基轻质材料的抗压强度、收缩率随养护龄期的增加而逐渐增大,养护14d时达到最大值,之后趋于稳定;水泥基轻质材料由于其轻质多孔的特点,应尽量选择大尺寸试块进行收缩率检测;选用将泡沫送入搅拌好的水泥浆中制备的产品,密度低、收缩小,更能体现材料的特点。     

Microbial synthesis and properties of poly(3-hydroxybutyrate-co-4-hydroxybutyrate)

Microbial synthesis of copolymers of [R]-3-hydroxybutyrate (3HB) and 4-hydroxybutyrate (4HB), P(3HB-co-4HB), by Alcaligenes eutrophus, Alcaligenes latus, and Comamonas acidovorans from various carbon sources has been studied. The copolyester compositions varied from 0 to 100 mol% 4HB, depending on the microorganism and the combination of carbon substrates supplied. The thermal and physical properties of compositions with 0–100 mol% 4HB were investigated. The copolyesters represented a wide variety of polymeric materials, from hard crystalline plastic to very elastic rubbers, depending on composition. The copolyester films with high 4HB fractions (64–100 mol% 4HB) exhibited the characteristics of a thermoplastic elastomer, and the tensile strength increased from 17 to 104 MPa as the 4HB fraction increased. The enzymatic degradation of P(3HB-co-4HB) films was studied in an aqueous solution of extracellular polyhydroxybutyrate (PHB) depolymerase from Alcaligenes faecalis or lipase from Rhizopus delemer. The erosion rate of P(3HB-co-4HB) films was strongly dependent on the copolymer composition. In addition, environmental degradation of P(3HB-co-4HB) films in sea water was investigated.