Papers by Keyword: Mass Spectrometry

Abstract: In this report, we proposed a MALDI mass spectrometry-based approach to study the formation of glycated species by coupling carbonyl aldehydes of sugar and molecules nucleophilic groups via enzymatic oxidation. The proposed enzymatic glycation in vitro could be a simple method to obtain well-defined substrates useful to study biological properties and activities of proteins in clinical samples, during oxidative stress and disease.

Abstract: We describe the mass-spectrometric approach to the analysis of the water release in the course of wear experiments in vacuum conditions. The approach is tested in wear experiments with polyurethanes and their composites.

Abstract: Thermal stability of the sintered samples of uranium mononitride was investigated in high purity helium atmosphere at 1900° – 2300°С. Thermogravimetry analysis of samples showed that the weight loss in uranium nitride consists of two stages. On first stage decomposition of uranium mononitride and nitrogen release starts. On the second stage additional active evaporation of uranium metal happens. During heating of the samples, nitrogen was registered by mass spectrometry. Microstructure of the samples after high temperature tests showed irregularly distributed spherical particles of uranium metal.

Abstract: We have developed a new testing device, which is capable of detecting hydrogen gas evolution from the microstructural changes at the same timing. The device is composed of the tensile testing machine equipped with a high-speed microscope and two types of quadrupole mass spectrometers installed in the ultrahigh vacuum chamber. Sampling rate of microscopic observation is 2000 fps. Hydrogen or deuterium was pre-charged to the 7075 aluminum alloy by means of the slow strain rate deformation, together with the exposure under the humid air atmosphere. The hydrogen amount was measured by using a thermal desorption analysis in advance. As a result, it was revealed that hydrogen gas was evolved when the surface crack was generated around the notch root of the test specimen. SEM observation also showed that the initial crack is related to the propagation of grain boundary fracture around the notch root. When compared to the microstructure and the hydrogen gas evolution near the notch root, the hydrogen amount evolved at the grain boundary was estimated to be about 3.0×10^-7 mol/m².

Abstract: To study the dynamic variation of protein components and contents in Antheraea pernyi, 2D-PAGE, in this job, was used to investigate embryo development. Some special protein spots expression profiles changed obviously were analyzed by mass spectrometry. 2D-PAGE results showed that the protein spots increased from 370 at the development stage of 12 h to 422 at 300 h. Eighteen special protein spots were identified by LC-MS/MS, and 8 kinds of proteins are found to include heat shock proteins families, Vitellogenin, KK-42-binding protein, actin-depolymerizing factor 1, etc., which are mainly involved in some important processes. Analyze the function of those proteins, so as to accumulate basic information on embryonic development in A. pernyi.

Abstract: Fruit mulberry cultivation has become a new field of modern sericulture, and quite a number of studies were focused on the growth and development of mulberry flowers and fruits. In order to explore the molecular mechanism of development and regulation of mulberry pistillate flower, the total protein were extracted from the flowering style (with the stigma) and ovary with fruit mulberry variety "Da 10" as materials, separated by two-dimensional electrophoresis and identified by mass spectrometry. The results showed that there were significant differential expressions in different tissues, and 20 proteins with specific expression were detected in the style of pistillate flower. By mass spectrometry analysis, database retrieval and bioinformatics software analysis, these protein components were given functional annotation, mainly related to the biosynthetic metabolism of protein and flavonoid, stress response and redox reaction. Additionally, glucan endo-1,3-beta-glucosidase involved in cell wall metabolism was detected to be up-regulated expression and lipoxygenase participating in membrane lipid oxidation reaction was detected to be down-regulated expression in the style compared with that in the ovary. It illustrated that the differential expression of these proteins in style were closely related to pollen germination, pollen tube growth or intrusion of other xenobiotics.

Abstract: The silkworm fat body is the organ of many intermediary metabolic processes and sustenance of growth throughout the life, and its proteins are responsible for storing nutrients, providing energy and regulating hormones. To date, detailed differential expressions of fat body proteins have not been clearly analyzed. In this research, fat body proteins were extracted from the larvae of the 5^th day of the 5^th instar, un-pupated larvae of spinning end and pupae of pupating day of the multivoltine silkworm variety Da Zao, and the differential expressed proteins were characterized by two-dimensional gel electrophoresis, followed by mass spectrometry identification and informatics method. 14 stage-specific expression proteins were detected and confirmed. Among them, 7 proteins were accurately identified, such as actin, calponin-like protein, beta-tubulin, hypothetical protein, antichymotrypsin precursor and 30K protein precursor etc. The biological roles of these important proteins during the larval-pupal developmental stages were discussed.

Abstract: Cryptotanshinone, tanshinone I, and tanshinone IIA were analyzed by High-performance liquid chromatography /electrospray ionization-mass spectrometry. MSⁿ spectra were obtained and optimized by energy collision induced dissociation (CID) from [M+H]⁺ ions, the effect of collision energy on production of fragmental ions were studied and optimal signals were achieved. With the collision energy of 35%, tanshinones have optimal signals of fragmental ions and maximal amounts of product fragment ions respectively. The fragmentation pathways for the compounds were studied, and this information would be helpful for the quantitative and pharmacokinetic analysis of tanshinones.

Abstract: Applying thermogravimetry coupled with mass spectrometry, a pyrolysis analysis of a long flame coal from Chinese Hami was carried out. The results show: In the temperature range between 400°C and 600°C, the degradation of the carbonaceous matrix and the evolution of relatively high molecular weight species result in the abundant release of CH₄, C₃H₆, C₆H₆, C₇H₈, C₈H₁₀ and otherwise gas in the coal sample. The weight loss between 400°C and 600°C occupies a main proportion in the total weight loss. In the temperature range between 600°C and 900°C, the condensation of the aromatic ring and the decomposition of mineral matter result in the abundant release of H₂, CO₂, C₆H₆ and otherwise gas.

Abstract: A laboratory-made the efficient photochemical degradation experimental device, combined with high performance liquid chromatography-tandem diode array detector device (DAD), fluorescence detector (FLD), mass spectrometer detector (MS), research fenvalerate its photo degradation. The structure of the spectral characteristics is the product, photo degradation reaction kinetics of degradation products, suggesting fenvalerate light chemical degradation process in an aqueous solution. The spectral characteristics of fenvalerate under ultraviolet light can be degraded into smaller organic molecules; maternal and main product have strong UV - visible absorption, fenvalerate are weakly fluorescent substance in the aqueous solution. The major products are strong fluorescent substance. Almost no effect The photo degradation kinetic data show fenvalerate photo degradation in an aqueous solution to approximate a reaction of the reaction; pesticide initial concentration, the pH value of the aqueous solution of pesticides photo degradation reaction rate; To accelerate the increase of salinity, light intensity fenvalerate in aqueous photo degradation reaction rate; significant influence of small organic molecules, with the type of small organic molecules.