Screening method for isopeptides from small ubiquitin-related modifier-conjugated proteins by ion mobility mass spectrometry

Posttranslational modification by the small ubiquitin-related modifier (SUMO) is a highly regulated modification, which is often restricted to very specific cellular events. A number of analytical strategies for identification of SUMOylated proteins have been previously reported in the literature. A new screening method for SUMOylated peptides based on ion mobility mass spectrometry is presented. Using poly-SUMO2 as a model system, a two-enzyme trypsin/chymotrypsin digestion was performed to reduce the size of the isopeptide conjugated to the substrate lysine residue. Traveling wave ion mobility mass spectrometry was used to screen for peptides containing the QQQTGG isopeptide tag from SUMO, which increases the mass and size of the peptide by 618 Da. This increase in mass along with solution conditions to promote higher charge states allows the isopeptides to be separated from the typically smaller and lesser charged linear peptides. On the basis of these findings, this method can be used as a quick and easy screening method for identifying possible SUMO isopeptides.     

Direct parameter extraction method for deep submicrometer metal oxide semiconductor field effect transistor small signal equivalent circuit

A new direct parameter extraction method to determine the small signal equivalent circuit model for deep submicrometer metal oxide semiconductor field effect transistors (MOSFETs) is presented here. This method is a combination of the test structure and analytical methods without reference to numerical optimisation. The main advantage of this method is that the extrinsic resistances, inductances, as well as substrate parasitics can be obtained using a set of exact closed equations based on the cut-off mode S-parameter on wafer measurements. Good agreement is obtained between the simulated and measured results for a 90 nm MOSFET in the frequency range of 50-40 GHz over a wide range of bias points.     

Photoimmobilization of proteins for affinity capture combined with MALDI TOF MS analysis

Affinity capture surfaces can be prepared in a number of ways. A method of obtaining such surfaces through UV-activated immobilization of binding proteins using a benzophenone derivative is reported. Photoimmobilized protein G was used to selectively capture and preconcentrate bovine IgG from a mixture with BSA, and the affinity of photoattached concanavalin A toward ovalbumin was compared with that of commercially available concanavalin A on agarose beads. The results of the capture after tryptic digestion were analyzed by MALDI TOF MS. Immobilized trypsin was also prepared through photoimmobilization and later used to digest hemoglobin. Immobilized enzyme digestion resulted in more partial cleavages than solution-phase digestion. More methionine and tryptophan oxidation was also observed. Photoimmobilization was shown to be a quick and easy way of immobilizing ligands on surfaces.     

一种提取图像目标边缘的新方法

提出一种基于阈值分割技术和形态学相结合的图像目标边缘提取方法,用Top-hat变换后的图像与原始图像相加再减去Bottom-hat变换后的图像以得到最大对比度的图像,继而进行自动图像阈值分割,再用圆形模板执行形态学闭合操作提取边缘,完全去除内部不感兴趣的细节,并保持边缘的连贯性。仿真结果表明,该方法能很好地提取目标边缘,而实际计算量只有传统方法的44.6%～70.2%,且具有较好的抗噪声能力。     

车辆悬架零部件载荷谱提取方法研究

优选载荷谱提取方法是提高汽车悬架零部件疲劳性能分析精度的关键.基于此,以某紧凑型SUV和某中级轿车为测试车型,通过实车试验场强化路面和室内振动台架试验采集得到轮心六分力和悬架多个监测部位的加速度、位移响应信号;实测整车参数并在ADAMS软件中建立整车刚柔耦合动力学模型;采用虚拟迭代法和约束加载法对多种振动台工况进行仿真...     

深度神经网络的语音深度特征提取方法

为了提升连续语音识别系统性能,将深度自编码器神经网络应用于语音信号特征提取。通过堆叠稀疏自编码器组成深度自编码器(Deep Auto-Encoding,DAE),经过预训练和微调两个步骤提取语音信号的本质特征,使用与上下文相关的三音素模型,以音素错误率大小为系统性能的评判标准。仿真结果表明相对于传统梅尔频率倒谱系数(Mel-Frequency Cepstral Coefficient,MFCC)特征以及优化后的MFCC特征,基于深度自编码器提取的深度特征更具优越性。     

环形子孔径检测技术中测量数据的准确提取方法

环形子孔径拼接测试技术是一种无需辅助元件就能检测旋转对称大口径非球面镜的有效手段。根据该技术的检测原理及基于Zemike多项式的“拼接”算法,提出了一种相应的环形子孔径数据提取方法。该方法基于商用相移干涉仪的CCD成像系统和其数据处理软件提供的Mask编辑功能,利用被测镜面上方的三个可移动的基准标记进行绝对定位,给出了具体的实施方案。对一口径700mm、F2的抛物面主镜进行实验,研究结果表明,该数据提取方法操作简单可行,适合于加工车间的实施,取得了符合“拼接”算法需求的子孔径测试数据和对应环带的内外半径值。     

A novel pattern extraction method for time series classification

Multivariate time series classification is of significance in machine learning area. In this paper, we present a novel time series classification algorithm, which adopts triangle distance function as similarity measure, extracts some meaningful patterns from original data and uses traditional machine learning algorithm to create classifier based on the extracted patterns. During the stage of pattern extraction, Gini function is used to determine the starting position in the original data and the length of each pattern. In order to improve computing efficiency, we also apply sampling method to reduce the searching space of patterns. The common datasets are used to check our algorithm and compare with the naive algorithms. Experimental results are shown to reveal that much improvement can be gained in terms of interpretability, simplicity and accuracy.     

Nitrilotriacetic acid-coated magnetic nanoparticles as affinity probes for enrichment of histidine-tagged proteins and phosphorylated peptides

We herein demonstrate superparamagnetic Fe3O4 nanoparticles coated with nitrilotriacetic acid derivative (NTA) that can bind with different immobilized metal ions are capable of probing diverse target species. Immobilized Ni(II) on the surfaces of the NTA-magnetic nanoparticles have the capability of selectively trapping histidine (His)-tagged proteins such as a mutated streptopain tagged with 6x His, i.e., C192S (MW approximately 42 kDa), from cell lysates. Enrichment was achieved by vigorously mixing the sample solution and the nanoparticles by pipetting in and out of a sample vial for only 30 s. After enrichment, the probe-target species could be readily isolated by magnetic separation. We also characterized the proteins enriched on the affinity probes using on-probe tryptic digestion under microwave irradiation for only 2 min, followed by matrix-assisted laser desorption/ionization mass spectrometry analysis. Using this enrichment and tryptic digestion, the target species can be rapidly enriched and characterized, reducing the time required for carrying out the complete analysis to less than 10 min. Furthermore, when either Zr(IV) or Ga (III) ions are immobilized on the surfaces of the NTA-magnetic nanoparticles, the nanoparticles have the capability of selectively enriching phosphorylated peptides from tryptic digests of alpha-, beta-caseins, and diluted milk. The detection limit for the tryptic digests of alpha- and beta-caseins is approximately 50 fmol.     

Binding affinity of fluorochromes and fluorescent proteins to Taxol™ crystals

The ability of Taxol (paclitaxel) to bind and stabilize microtubules is the basis for its use as an anti-mitotic drug as well as an additive for in vivo and in vitro studies of microtubules. The low solubility of Taxol in aqueous solutions, however, facilitates the formation of Taxol crystals that can be decorated with fluorescent tubulin. In cells treated with Taxol, these decorated Taxol crystals may be mistaken for self-assembled tubulin asters when observed with a fluorescent microscope. We confirmed via fluorescent and differential interference contrast microscopy that Taxol crystals can be decorated not only with fluorescent tubulin but also with other fluorescent proteins and fluorochromes without perturbing their morphology. We used theoretical calculations to further investigate Taxol-fluorescent agent interactions. Using computational docking studies we identified a new, potential Taxol binding site within the tubulin dimmer, allowing the interaction between crystalline Taxol and tubulin. Our calculations, however, show that fluorescent tubulin binding to Taxol crystals is more favorable via the fluorochromes covalently linked to the tubulin dimmers, rather than via the new Taxol-binding site, what is in accordance with our experimental data.     

基于相位法的密集小波公共脊线提取方法

针对传统小波脊线提取方法对密集脊线的提取存在着分辨率不足等缺点,提出一种基于相位法的密集小波公共脊线提取方法。通过分析密集单频叠加信号和密集调频叠加信号的小波公共脊线的相位特点,利用小波脊线的相位法来提取信号的公共脊线。仿真算例结果表明:该方法能有效地提取出密集小波公共脊线,且方法简单、准确,具有较快的收敛性。将其应用于实际齿轮箱故障分析中,能有效地提取故障特征,诊断出齿轮箱故障。     

弱小目标检测算法性能评价的回归分析方法

针对弱小目标检测算法的特点,建立了一种对算法性能进行评价的机制和方法。以图像特征指标作为输入量,算法性能指标作为输出量,用响应函数模型描述二者之间的关系,通过回归分析对算法的性能做出了评价。利用所建立的方法,分别对一种基于中值滤波和一种基于形态学滤波的检测算法进行了分析和比较,结果表明,对于试验所采用的背景图像情况,后者对弱小目标的检测性能总体上要优于前者。     

基于特征端元提取的像元分解方法

通过对端元概念的引申,提出了更具一般性的特征端元的概念,从而将端元方法的适用范围从高光谱数据拓展到了多光谱数据和全色遥感数据.同时改进了端元提取算法,并提出了基于特征端元提取的像元分解方法.实验结果表明,基于特征端元提取的混合像元分解方法可以得到较好的像元分解结果,并且该方法与传统的端元概念及混合像元分解结果具有良好的可比性.     

A method for extraction and quantification of Ginkgo terpene trilactones

A method was developed for the extraction and quantification of pharmacologically active terpene trilactones (ginkgolides, bilobalide) from the tissues of Ginkgo biloba L. and pharmaceutical ginkgo products by RP-HPLC, based on the theory of terpene trilactones ionization. Four ginkgolides (GA, GB, GC, GJ) and bilobalide (BB) from both the ginkgo leaves and commercially available ginkgo extracts were quantitatively extracted by using this method. The recovery rate of the method was 97.5-100% with RSD of 1.2-2.8%. The detection limit was 0.05-0.1 microg, and the linear range was 0.1-12 microg. This detection limit represents a marked improvement over previously reported methods, suggesting the new method is a viable technique for routine analysis of ginkgo terpene trilactones in natural and commercial samples. The method reported by van Beek et al. in 1991 (van Beek, T. A.; Scheeren, H. A.; Rantio T.; Melger, W. C.; Lelyveld, G. P. J. Chromatogr. 1991, 543, 375-387.) was used as a reference method to monitor the accuracy of extraction and analysis in this study. SSI-MS technique was used to identify isolated target components. Carbohydrase treatment and solubility of terpene trilactones in various solvents were also discussed.