Heterogeneity within MALDI samples as revealed by mass spectrometric imaging

While matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) has revolutionized the manner by which many large molecules are characterized, the highly variable appearance of MALDI mass spectra remains a concern. We have developed MALDI-based imaging as a diagnostic tool for examining the relationships between preparation strategy, sample morphology, and spectral quality. The imaging protocol involves the automated acquisition of mass spectra at 400-1600 positions within a single sample, followed by off-line processing and image display. Several sample types have been characterized, including a simple peptide mixture prepared in dried droplets of 2,5-dihydroxybenzoic acid and in thin films of alpha-cyano-4-hydroxycinnamic acid as well as a complex biological sample consisting of intact peptidergic neurons from the marine mollusk Aplysia californica. Imaging experiments provide a wealth of unbiased information concerning sample defects, spectral reproducibility, mass accuracy, differential analyte distributions, and the validity of internal standards.     

Metabolic differentiation of neuronal phenotypes by single-cell capillary electrophoresis-electrospray ionization-mass spectrometry

Single-cell mass spectrometry (MS) is a rapidly emerging field in metabolic investigations. The inherent chemical complexity of most biological samples poses analytical challenges when using MS platforms to measure sample content without prior chemical separation. Here, a single-cell capillary electrophoresis (CE) system was coupled with electrospray ionization (ESI) MS to enable the simultaneous measurement of a vast array of endogenous compounds in over 50 identified and isolated large neurons from the Aplysia californica central nervous system. More than 300 distinct ion signals (m/z values) were detected from a single neuron in the positive ion mode, 140 of which were selected for chemometric data analysis. Metabolic features were evaluated among six different neuron types (B1, B2, left pleural 1 (LPl1), metacerebral cell (MCC), R2, and R15) chosen for their various physiological functions. The results indicated chemical similarities among some neuron types (B1 to B2 and LPl1 to R2) and distinctive features for others (MCC and R15 cells). The quantitative nature of the MS platform allowed the comparison of metabolite levels for specific neurons. The CE-ESI-MS approach for examination of individual nanoliter-volume cells as described herein is readily adaptable to other volume-limited samples.     

搪瓷用含钛热轧高强钢板的显微组织和力学性能研究

热水器搪瓷内胆具有使用寿命长、无毒无害以及高耐蚀等特点,得到了广泛的应用,可替代传统的不锈钢、热镀锌和塑料等材料制作的内胆。为了满足成型、焊接和涂搪等要求,制作搪瓷内胆的钢板必须具有高强度以及优良的成型性、焊接性和涂搪性。研究表明,含钛热轧高强钢中钛主要以碳化物和氮化物的形式存在,不仅具有优良的焊接性和涂搪性,在焊接过程中和高温烧成时由于钛的析出物能有效地抑制晶粒长大,保持较高的强度。通过优化碳、锰和钛等元素的匹配,开发了4个不同屈服强度级别(210 MPa,245 MPa,330 MPa和360 MPa)的热轧搪瓷钢板。     

Evaluation of human immunodeficiency virus type 1 (HIV-1)-specific cytotoxic T-lymphocyte responses utilizing B-lymphoblastoid cell lines transduced with the CD4 gene and infected with HIV-1

Analysis of major histocompatibility complex-restricted cytotoxic T lymphocytes (CTL) capable of killing human immunodeficiency virus type 1 (HIV-1)-infected targets is essential for elucidating the basis for HIV-1 disease progression and the potential efficacy of candidate vaccines. The use of primary CD4+ T cells with variable infectivity as targets for such studies has significant limitations, and immortal autologous cells with high levels of CD4 expression that can be consistently infected with HIV-1 would be of much greater utility. Therefore, we transduced Epstein-Barr-virus-transformed B-lymphoblastoid cell lines (LCL) with a retroviral vector, LT4SN, containing the human CD4 gene. Stable LCL in which more than 95% of cells expressed membrane CD4 were obtained. Aliquots were infected with HIV-1, and, after 4 to 7 days, nearly all of the cells contained cytoplasmic gag and produced high levels of p24 antigen. The ability of major histocompatibility complex-restricted CD8+ CTL to lyse such HIV-1-infected CD4-transduced LCL (LCL-CD4HIV-1) was evaluated. These autologous targets were lysed by CTL generated from an HIV-1-uninfected vaccinee over a broad range of effector-to-target ratios. Similarly, the LCL-CD4HIV-1 were efficiently lysed by fresh circulating CTL from HIV-1-infected individuals, as well as by CTL activated by in vitro stimulation. Both HIV-1 env- and gag-specific CTL effectors lysed LCL-CD4HIV-1, consistent with the cellular expression of both HIV-1 genes. The LCL-CD4HIV also functioned as stimulator cells, and thus are capable of amplifying CTL against multiple HIV-1 gene products in HIV-1-infected individuals. The ability to produce HIV-1-susceptible autologous immortalized cell lines that can be employed as target cells should enable a more detailed evaluation of vaccine-induced CTL against both homologous and disparate HIV-1 strains. Furthermore, the use of LCL-CD4HIV-1 should facilitate the analysis of the range of HIV-1 gene products recognized by CTL in seropositive persons.     

基于行为安全理论的矿工不安全动作管理APP研究

为转变传统闭环检查监管不安全动作的管理模式,解决煤矿不安全动作管理信息化技术中存在的缺少与行为安全理论的结合、无法挖掘不安全动作产生机理、无法有效统计分析不安全动作数据等问题,基于行为安全理论与瑞士奶酪模型(SCM),在验证某煤矿不安全动作管理情况与上述理论相容性的基础上,通过应用Android系统平台、JAVA编程语...