Simple and convenient preparation of Au-Pt core-shell nanoparticles on surface via a seed growth method

Au-Pt core-shell nanoparticles were prepared on glass surface by a seed growth method. Gold nanoparticles were used as seeds and ascorbic acid-H2PtCL6 solutions as growth solutions to deposit Pt shell on the surface of gold nanoparticles. These core-shell nanoparticles and their growth process were examined by UV-Vis spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and field-emission environmental scanning electron microscopy and the results indicated that the deposition speed was fast and nanoparticles with obvious core-shell structure could be obtained after 2 min. Moreover, this seed growth method for preparation of the core-shell nanoparticles is simple and convenient compared with other seed growth methods with NH4OH as a mild reductant. In addition, electrochemical experiments indicated that these Au-Pt core-shell nanoparticles had similar electrochemical properties to those of the bulk Pt electrode.

Synthesis of barium fluoride nanoparticles from microemulsion

The cetyltrimethylammonium bromide (CTAB)/2-octanol/water microemulsion system was used to synthesize barium fluoride nanoparticles. X-ray powder diffraction (XRD) analysis showed that the products were single phase. The results of scanning electron microscopy and calculations using the Scherrer equation from the line widths of the XRD have been used to estimate the average particle sizes of the powder products. The results showed that the nanoparticle size was affected by water content and surfactant (CTAB) concentration. As water content decreases from 14.2 to 9.47% (w/w), the particle size decreases from 75 to 40 rim. In addition, increasing the reaction times from 5 to 120 min increases the particle size from 75 to 150 rim, and increasing the amount of surfactant decreases the size of the particle. Luminescence spectra of the BaF2:Ce nanoparticles are also discussed.

Real-time immunoassay of ferritin using surface plasmon resonance biosensor

A surface plasmon resonance (SPR) biosensor was used for the first time to determine the concentration of ferritin in both HBS-EP buffer and serum. The monoclonal antibody was immobilized on the carboxymethyl dextran-modified gold surface by an amine coupling method. The interaction of antibody with antigen was monitored in real-time. The signal was enhanced by sandwich amplification strategy to improve the sensitivity and specificity of the immunoassay, especially in serum. The linear range of the assay in serum is over 30-200 ng ml with the detection limit of 28 ng ml(-1). The sensitivity, specificity, and reproducibility of the assay are satisfactory. The analyte and enhancement antibody-binding surface could be regenerated by pH 2.0 glycine-HCl buffer and the same antibody-immobilized surface could be used for more than 50 cycles of ferritin binding and regeneration.

Isotope effect in proton-transfer and association-dissociation reactions for butylamine by ultrasonic relaxation methods

Ultrasonic absorption coefficients were measured for butylamine in heavy water (D2O) in the frequency range from 0.8 to 220 MHz and at concentrations from 0.0278 to 2.5170 mol dm(-3) at 25 degrees C; two kinds of relaxation processes were observed. One was found in relatively dilute solutions (up to 0.5 mol dm(-3)), which was attributed to the hydrolysis of butylamine. In order to compare the results, absorption measurements were also carried out in light water (H2O). The rate and thermodynamic parameters were determined from the concentration dependence of the relaxation frequency and the maximum absorption per wavelength. The isotope effects on the diffusion-controlled reaction were estimated and the stability of the intermediate of the hydrolysis was considered while comparing it with the results for propylamine in H2O and D2O. Another relaxation process was observed at concentrations greater than 1 mol dm(-3) in D2O. In order to examine the solution characteristics, proton NMR measurements for butylamine were also carried out in D2O. The chemical shifts for the gamma- and delta-proton in butylamine molecule indicate the existence of an aggregate. From profiles of the concentration dependence of the relaxation frequency and the maximum absorption per wavelength of sound absorption, the source of the relaxation was attributed to an association-dissociation reaction, perhaps, associated with a hydrophobic interaction. The aggregation number, the forward and reverse rate constants and the standard volume change of the reaction were determined. It was concluded from a comparison with the results in H2O that the hydrophobic interaction of butylamine in D2O is stronger than that in H2O. Also, the isotope effect on this reaction was interpreted in terms of the solvent structure.

Characterization of the structural and functional changes of hemoglobin in dimethyl sulfoxide by spectroscopic techniques

Circular dichroism (CD), fourier transform infrared (FTIR), and fluorescence spectroscopy were used to explore the effect of dimethyl sulfoxide (DMSO) on the structure and function of hemoglobin (Hb). The native tertiary structure was disrupted completely when the concentration of DMSO reached 50% (v/v), which was determined by loss of the characteristic Soret CD spectrum. Loss of the native tertiary structure could be mainly caused by breaking the hydrogen bonds, between the heme propionate groups and nearby surface amino acid residues, and by disorganizing the hydrophobic interior of this protein. Upon exposure of Hb to 52% DMSO for ca. 12 h in a D2O medium no significant change in 1652 cm(-1) band of the FTIR spectrum was produced, which demonstrated that alpha-helical structure predominated. When the concentration of DMSO increased to 57%: (1) the band at 1652 cm(-1) disappeared with the appearance of two new bands located at 1661 and 1648 cm(-1); (2) another new band at 1623 cm(-1) was attributed to the formation of intermolecular beta-sheet or aggregation, which was the direct consequence of breaking of the polypeptide chain by the competition of S=O groups in DMSO with C=O groups in amide bonds. Further increasing the DMSO concentration to 80%, the intensity at 1623 cm(-1) increased, and the bands at 1684, 1661 and 1648 cm(-1) shifted to 1688, 1664 and 1644 cm(-1), respectively. These changes showed that the native secondary structure of Hb was last and led to further aggregation and increase of the content of 'free' amide C=O groups. In pure DMSO solvent, the major band at 1664 cm(-1) indicated that almost all of both the intermolecular beta-sheet and any residual secondary structure were completely disrupted. The red shift of the fluorescence emission maxima showed that the tryptophan residues were exposed to a greater hydrophilic environment as the DMSO content increased. GO-binding experiment suggested that the biological function of Hb was disrupted seriously even if the content of DMSO was 20%. (C) 1998 Elsevier Science B.V. All rights reserved.

Genetic linkage map of bay scallop, Argopecten irradians irradians (Lamarck 1819)

The bay scallop (Argopecten irradians irradians Lamarck 1819) has become one of the most important aquaculture species in China. Genetic improvement of cultured bay scallop can benefit greatly from a better understanding of its genome. In this study, we developed amplified fragment length polymorphisms (AFLPs) and simple sequence repeat markers from expressed sequence tags (EST-SSRs) for linkage analysis in bay scallop. Segregation of 390 AFLP and eight SSR markers was analysed in a mapping population of 97 progeny. Of the AFLP markers analysed, 326 segregated in the expected 1:1 Mendelian ratio, while the remaining 74 (or 19.0%) showed significant deviation, with 33 (44.6%) being deficient in heterozygotes (A/a). Among the eight polymorphic EST-SSR loci, one marker (12.5%) was found skewing from its expected Mendelian ratios. Eighteen per cent of the markers segregating from female parent were distorted compared with 21% of the markers segregating from male parent. The female map included 147 markers in 17 linkage groups (LGs) and covered 1892.4 cM of the genome. In the male map, totally 146 AFLP and SSR markers were grouped in 18 LGs spanning 1937.1 cM. The average inter-marker spacing in female and male map was 12.9 and 13.3 cM respectively. The AFLP and SSR markers were distributed evenly throughout the genome except for a few large gaps over 20 cM. Although preliminary, the genetic maps presented here provide a starting point for the mapping of the bay scallop genome.

The complete mitochondrial genomes of two common shrimps (Litopenaeus vannamei and Fenneropenaeus chinensis) and their phylogenomic considerations

Complete mitochondrial genomes have proven extremely valuable in helping to understand the evolutionary relationships among metazoans. However, uneven taxon sampling may lead to unclear or even erroneous phylogenetic topologies. The decapod crustaceans are relatively well-sampled, but sampling is still uneven within this group. We have sequenced the mitochondrial genomes of two shrimps Litopenaeus vannamei and Fenneropenaeus chinensis. As seen in other metazoans, the genomes contain a standard set of 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes and an AT-rich non-coding region. The gene arrangements are consistent with the pancrustacean ground pattern. Both the pattern of gene rearrangements and phylogenomic analyses using concatenated nucleic acid and amino acid sequences of the 13 mitochondrial protein-coding genes strengthened the support that Caridea and Palinura are primitive members of Pleocyemata. These sequences, in combination with two previously published penaeid mitochondrial genomes, suggest that genera within the family Penaeidae have the following relationship: (((Penaeits + Fenneropenaett.) + Litopeiiaelts) + Marsupenaeus). The analyses of nucleic acid and amino acid sequences of the mitochondrial genomes also strongly support the monophyly of Penaeidae, Brachyura and Pleocyemata. In addition, the analyses of the average Ka/Ks in the 13 mitochondrial protein-coding genes of penaeid shrimps indicated a strong purifying selection within this group.

Improvement of different source function expressions in SWAN model for the Bohai Sea

The simulating wave nearshore (SWAN) wave model has been widely used in coastal areas, lakes and estuaries. However, we found a poor agreement between modeling results and measurements in analyzing the chosen four typical cases when we used the default parameters of the source function formulas of the SWAN to make wave simulation for the Bohai Sea. Also, it was found that at the same wind process the simulated results of two wind generation expressions (Komen, Janssen) demonstrated a large difference. Further study showed that the proportionality coefficient alpha in linear growth term of wave growth source function plays an unperceived role in the process of wave development. Based on experiments and analysis, we thought that the coefficient alpha should change rather than be a constant. Therefore, the coefficient alpha changing with the variation of friction velocity U (*) was introduced into the linear growth term of wave growth source function. Four weather processes were adopted to validate the improvement in the linear growth term. The results from the improved coefficient alpha agree much better with the measurements than those from the default constant coefficient alpha. Furthermore, the large differences of results between Komen wind generation expression and Janssen wind generation expression were eliminated. We also experimented with the four weather processes to test the new white-capping mechanisms based on the cumulative steepness method. It was found that the parameters of the new white-capping mechanisms are not suitable for the Bohai Sea, but Alkyon's white-capping mechanisms can be applicable to the Bohai Sea after amendments, demonstrating that this improvement of parameter alpha can improve the simulated results of the Bohai Sea.

青藏高原红景天药材的HPLC指纹图谱

利用高效液相色谱法建立了青藏高原红景天的色谱指纹图谱.固定相采用C18反相色谱柱,流动相为甲醇:0.1%磷酸水(v/v＝15:85);检测波长220 nm;流速为1.0 mL/min.通过比较发现红景天样品的8个主要共有峰,可作为鉴别红景天药材的主要依据.方法简便快速,为中药品种的鉴定提供了较全面的信息.

基于主动轮廓模型的图像分割及目标跟踪算法研究

论文在中国科学院国防科技创新基金课题支持下，对主动轮廓模型的图像分割和目标跟踪算法进行了研究。 对复杂自然背景下人造目标的边缘提取问题进行了讨论，提出基于分形维数特征的分形参数主动轮廓模型和分形几何主动轮廓模型。该模型允许初始轮廓远离目标的边缘，降低了模型对初始轮廓的依赖性。 对主动轮廓跟踪模型进行了研究，提出一种基于形状约束的参数主动轮廓跟踪模型。该模型可以克服弱边缘及强背景等噪声对轮廓的吸引和干扰，保持了目标的基本形状，实现和改善了对具有尖角、深凹和狭长分支等不规则形状目标的边缘跟踪。 提出一种基于C-V模型的水上桥梁目标分割和识别算法。该算法能够较好地解决远距离小目标水上桥梁及灰度梯度较弱图像的桥梁分割和识别问题。 对Chan-Vese提出的水平集图像分割模型进行了改进，提出一种无需水平集重新初始化的C-V模型。该模型不仅提高了C-V模型的演化速度，而且实现了水平集函数初始化的灵活性。 基于区域特性及Mumford-Shah技术，提出一种基于能量最小化的主动分界线模型来实现对天际线或者某些同质区域非闭合分界线的检测。该模型可以提取无梯度信息或者梯度信息较弱的区域边界，并具有较强的抗噪性。

曲线演化图像分割和森林烟火预警系统

随着计算机技术，图像采集技术和数据存储技术等的进步，图像处理的应用领域越来越广泛。很多的应用系统是综合利用了电子，通讯和图像处理等技术而开发出来的，图像处理往往是系统的核心部分。图像分割是图像处理的核心技术，也是图像处理技术中的难点。所以研究图像分割技术具有非常重要的意义。 传统的图像分割方法有：使用模板对图像进行边缘检测等；利用滤波处理，频谱分析等数字信号处理处理技术进行分割。80年代末以来，偏微分方程方法越来越多地应用到图像分割领域中，已成为图像分割的有力工具。本文对基于偏微分方程的图像分割方法进行研究，介绍单开曲线演化分割算法，并基于Mumford-Shah模型提出一种带状目标分割方法。这种方法能将图像中的带状区域从图像中分割出来－这里假定带状区域的边界可用单值函数表示。与其它方法，如边缘检测分割，C-V模型分割和单开曲线分割相比，本文提出的方法得到的分割结果有与目标的边界吻合的更好，抗噪能力强等优点。 本文介绍了通过对可见光摄像机所拍摄图像进行分析来检测火的森林烟火预警系统。该系统是通过检测烟的存在来判断是否有火情。图像处理软件是森林烟火预警系统的核心组成部分。评价火灾预警系统性能有两个标准。一个是一旦发生火灾，预警系统能否快速地发出火警信号；另一个是在没有火情时，预警系统是否不报警，即误警率是否低。图像分割在设计图像处理算法时，主要在两个地方得到应用。在图像预处理阶段，利用单开曲线演化分割算法或带状区域的分割算法将森林区域分割出来。这样是为了在对图像进行处理时消除非森林区域中的目标对识别结果的影响，降低误警率。在图像处理阶段，利用图像分割算法将烟从图像中分割出来，准确及时报警。

基于变分的主动轮廓图像分割方法

图像分割是图像处理中很重要的一个问题，是计算机视觉的基础。因为它能够简化信息的存储和表示，从而能够对获取的图像内容进行智能解释，所以在很多应用问题中，图像分割是必不可少的过程，如医学图像处理，环境三维重建及自动目标识别等。图像分割的方法有很多种，如边缘检测，阈值，区域融合，分水岭及马尔可夫随机场等。虽然这些方法有其各自特点，但是它们在图象分割过程中不能充分将图像底层信息与高层信息结合，从而无法模拟人类视觉系统智能性。当图像底层信息不足时，这些仅基于数据驱动的分割模型无法达到令人满意的结果。尽管某种具体图像分割方法不可能满足所有图像分割要求，但利用尽可能多的高层与底层信息，将图像分割成有意义和人们所期望的区域始终是研究者所追求的目标。图像分割问题的数学建模和计算中有两个关键因素。第一是建立合适的分割模型将分割边界和分割区域的作用有效结合。第二是利用最有效的方法将分割边界和分割区域的几何特征统一到分割模型中。基于变分原理的主动轮廓图像分割将图像视为连续函数。这就使得研究者可以从连续函数空间角度来研究图像分割问题。这同时也为研究者提供严格的数学工具，如微分几何、泛函分析和微分方程等。为此它能很好的解决上述两个问题。第一，Mumford-Shah(M-S)模型为基于变分的主动轮廓分割模型提供了一完整的数学理论框架，并且Mumford-Shah模型从信息论的角度也能得到合理解释。第二，水平集方法能有效的表示分割边界和分割区域的几何特征。与其它方法相比，变分主动轮廓在理论和实际计算过程中都具有显著的优势。首先它能直接处理和表示各种重要的几何特征，如梯度、切向量、曲率等，并且能有效模拟很多动态过程，如线性和非线性扩散等。再则其可以利用很多已有的丰富数值方法进行分析和计算。本文基于变分原理与偏微分方程方法，利用主动轮廓模型具有结合底层图像信息与高层先验知识的特点，将特定先验知识与主动轮廓分割模型进行有效结合以弥补底层图像信息的不足，从而使主动轮分割廓模型具有更强的智能性。本文主要从两点对变分主动轮廓分割模型展开了研究：1、演化轮廓的形状约束；2、演化轮廓的梯度下降流约束及其滤波实现。其主要工作包括以下四个方面的内容：第一，基于M-S模型和样条曲线的开边界检测。本章通过对演化轮廓引入合理边界条件，利用样条曲线表示待检测的开曲线，将一般开曲线的检测问题变为合理的图像分割问题，从而达到一般开曲线检测目的。此方法称为开扩散蛇模型。一般开曲线的检测具有很多应用领域，如：河流、道路、天际线、焊缝等检测。第二，方差主动轮廓模型。在目标跟踪应用中，跟踪目标的主要运动形式表现为平移。本章将此作为一种先验知识与主动轮廓模型结合，提出了一种方差主动轮廓模型(HV)。此模型的特点是轮廓在演化过程中具有平移优先和快速的良好特性。它比已有的主动轮廓模型更适于自动目标跟踪领域。第三，基于M-S模型和隐式曲面变分方法的一般梯度下降流滤波器。本章为一般梯度下降流求取提供了统一框架及解决方法。首先本章将H0梯度下降流和一般梯度下降流统一到Mumford-Shah模型框架中，从而将一般梯度下降流的求取转换为一个极小化泛函问题，并利用隐式曲面变分方法对此极小化泛函进行求解。另外本章从滤波器设计角度出发，通过对H0梯度下降流滤波可以得到一般梯度下降流。滤波器的实现体现了内嵌于一般梯度下降流的先验属性。根据此思想，本章将对应于HV和H1主动轮廓的內积空间顺序组合，对H0梯度下降流进行顺序滤波，提出了一种既具有全局平移优先性又具有局部光滑速度场的主动轮廓，称为HV1主动轮廓。它将H0，H1和HV主动轮廓统一起来。第四，形状保持主动轮廓模型及其应用。针对某些特定目标的检测，本章提出了形状保持主动轮廓模型。此模型能够达到分割即目标的目的，同时能够给出目标的定量描述。基于此模型，本章实现了具有椭圆、直线和平行四边形轮廓特征目标的检测。椭圆形状约束用于眼底图像分割。直线和平行四边行分别用于自动目标识别中的天际线检测和机场跑道跟踪。

微机控制的红热钢板动态测长仪

本文叙述了微机控制的红热钢板动态测长仪的原理、工程公式的导出、软件功能及其特点。