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101.
102.
高效液相色谱/质谱法识别不同明胶酶解产物中特征多肽 总被引:3,自引:0,他引:3
在不同动物胶原蛋白序列比对基础上,利用高效液相色谱/质谱联用技术(HPLC/MS)建立一种通过特征多肽进行明胶鉴别的方法。实验以牛明胶和猪明胶为对象,序列比对结果表明,牛和猪的Ⅰ型胶原蛋白α1链和α2链均存在氨基酸序列差异。利用胰蛋白酶将牛明胶和猪明胶降解,通过HPLC/MS分析了两种明胶酶解产物中的多肽片段。结果表明:牛明胶和猪明胶酶解产物中均可检测出存在序列差异的特征性多肽,其氨基酸序列差异与两种胶原蛋白序列比对结果中的序列差异一致;酶解产物中特征多肽上的脯氨酸存在不同程度的羟基化修饰,特征多肽的相对含量主要受明胶分子量范围影响。利用HPLC/MS检测明胶酶解产物中的特征多肽是一种鉴别牛明胶和猪明胶的有效方法。 相似文献
103.
104.
Joana Antunes Quentin Gauthier Vanessa Aguiar-Pulido George Duncan Bruce McCord 《Electrophoresis》2021,42(9-10):1168-1176
Tissue-specific differentially methylated regions (tDMRs) are regions of the genome with methylation patterns that modulate gene expression in those tissue types. The detection of tDMRs in forensic evidence can permit the identification of body fluids at trace levels. In this report, we have performed a bioinformatic analysis of an existing array dataset to determine if new tDMRs could be identified for use in body fluid identification from forensic evidence. Once these sites were identified, primers were designed and bisulfite modification was performed. The relative methylation level for each body fluid at a given locus was then determined using qPCR with high-resolution melt analysis (HRM). After screening 127 tDMR's in multiple body fluids, we were able to identify four new markers able to discriminate blood (2 markers), vaginal epithelia (1 marker) and buccal cells (1 marker). One marker for each target body fluid was also tested with pyrosequencing showing results consistent with those obtained by HRM. This work successfully demonstrates the ability of in silico analysis to develop a novel set of tDMRs capable of being differentiated by real time PCR/HRM. The method can rapidly determine the body fluids left at crime scenes, assisting the triers of fact in forensic casework. 相似文献
105.
基于逆模型偏最小二乘法的高光谱亚像元目标探测方法研究 总被引:1,自引:0,他引:1
目前的高光谱亚像元目标探测算法主要是利用线性混合模型,在背景端元光谱已知的前提下,构造一定的检测算子逐像元判定是否含有亚像元目标。该算法需要较为精确的背景端元光谱先验信息,且目标探测结果受背景复杂度影响较大。从光谱维数据分析的角度出发,将逆模型偏最小二乘法(ILS)和马氏距离奇异值检测方法相结合进行亚像元小目标探测研究。首先建立目标光谱与像元光谱的逆模型,并对像元光谱与目标光谱进行正交变换预处理(SNV),再利用偏最小二乘算法(PLS)计算逆模型的回归系数向量,从而将多维的光谱信息降维,并突出目标光谱信息,最后计算各像元回归系数的马氏距离,判定马氏距离大于3σ的系数所对应的像元点为含有亚像元目标的像元点。该方法仅需要目标光谱的先验信息,对背景的复杂度不敏感。文章采用AVIRIS仿真数据将上述方法与常用的正交子空间投影算法(OSP)的计算结果进行比较,通过比较不同算法的受试者工作特征曲线(ROC)以及信噪比(SNR)变化曲线,证实了该算法具有较快的运算速度和较高的目标探测性能。 相似文献
106.
橙汁主要矿质元素含量的特征分析 总被引:1,自引:0,他引:1
矿质元素的含量与组成特征是评价橙汁品质与判断橙汁来源的重要指标。采用火焰原子吸收光谱法对我国重庆地区15个橙汁样品中钾,钙,钠,镁四种矿质元素的含量进行了测定,用箱线图和因子分析法对样品元素含量特征进行了分析。结果表明, 橙汁中钾元素含量最高(1 233.75~1 866.23 mg·L-1),其次为镁(77.51~167.15 mg·L-1)和钙(49.32~125.29 mg·L-1)元素,而钠元素含量最低(1.22~9.26 mg·L-1),该结果与欧盟果蔬汁工业协会(AIJN)提供的橙汁鉴伪与质量评价参考值范围基本一致;因子分析的结果表明,橙汁中钠元素含量的不同是区分冬橙与夏橙橙汁的主要因素。研究结果为我国橙汁品质评价、标准体系的建立及鉴伪研究提供了重要的基础数据。 相似文献
107.
Hermann Singer 《The Journal of mathematical sociology》2013,37(1):39-49
In a recent paper it was shown that the aliasing phenomenon, which leads to a severe identification problem in the estimation of stochastic differential equations, can be overcome by using a polygonal (or higher) approximation for the time paths of the exogenous variables. This work attempts to visualize the problem and presents several simulated trajectories of a continuous time AR(2)‐process (Ornstein‐Uhlenbeck‐process) together with the observationally equivalent structures. Furthermore it is shown that aliasing can even change the analytical properties of the time paths of the system: whereas the first component of the Ornstein‐Uhlenbeck‐process is differentiable, the trajectories of the aliasing structures are continuous, but not differentiable any more. 相似文献
108.
Siwei Wang Jesse Ward Sven Leyffer Stefan M. Wild Chris Jacobsen Stefan Vogt 《Journal of synchrotron radiation》2014,21(3):568-579
A novel approach to locate, identify and refine positions and whole areas of cell structures based on elemental contents measured by X‐ray fluorescence microscopy is introduced. It is shown that, by initializing with only a handful of prototypical cell regions, this approach can obtain consistent identification of whole cells, even when cells are overlapping, without training by explicit annotation. It is robust both to different measurements on the same sample and to different initializations. This effort provides a versatile framework to identify targeted cellular structures from datasets too complex for manual analysis, like most X‐ray fluorescence microscopy data. Possible future extensions are also discussed. 相似文献
109.
We study the existence of equilibrium positions for the load problem in Lubrication Theory. The problem consists of two surfaces in relative motion separated by a small distance filled by a lubricant. The system is described by the modified Reynolds equation (Elrod–Adams model) which describes the behavior of the lubricant and an extra integral equation given the balance of forces. The balance of forces allows to obtain the unknown position of the surfaces, defined with one degree of freedom. 相似文献
110.
Zhiyong SunGangquan Si 《Communications in Nonlinear Science & Numerical Simulation》2012,17(8):3461-3463
In this comment letter we point out that the main result of the recent paper [Xu Y, Zhou W, Fang J, Sun W. Topology identification and adaptive synchronization of uncertain complex networks with adaptive double scaling functions. Commun Nonlinear Sci Numer Simul 2011;16(18):3337-43] has certain errors. The mistakes are corrected and a correct version is presented in this letter. We further indicate that a sufficient condition has been neglected in a series of articles discussing the same topic of network topology identification; hence we hope this letter can help clarify some unclear concepts about this topic. 相似文献