Papers by Keyword: MS

Abstract: We proposed a MALDI mass spectrometry based approach to characterize walnut allergens. The strategy is based on the extraction of hydro-soluble tissue proteins followed by protein fractionation and mass-spectrometry analysis. Linear MALDI was adopted to evaluate the intact protein mass information and the presence of glycoproteins.

Abstract: Recycling is promising to dispose the wasted Poly (ethylene terephthalate) (PET) fibers currently. However, high temperature and oxygen in the recycling process may accelerate the degradation of PET and residual dyes, resulting in the volatile organic compounds (VOCs) emissions, which will do serious harm to the environment and human health. Exploring the source of VOCs is significant to remove VOCs and keep products safety. This study was carried out to investigate the influence of high temperature on the release of four VOCs (formaldehyde (CH₂O), acetaldehyde (C₂H₄O), benzene (C₆H₆) and toluene (C₇H₈)) during the recycling process of PET fibers, utilizing thermogravimetric analysis and differential thermal analysis coupled with mass spectrometric (TGA-DTA/MS). The atmospheres and heating conditions of esterification, polycondensation and melt spinning were simulated by TGA with various atmospheres and programmed heating processes (heating from 50 °C to 240 °C in Ar, 280 °C in Ar and 280 °C in air, respectively, and then maintaining for 30min). Bis (2-hydroxyethyl) terephthalate (BHET) (esterification product) and virgin PET (VPET) were used to explore the thermal degradation of PET. White PET popcorn, black PET popcorn and dyes were used to explore the effect of dyes on the release of VOCs. The results indicated that: (1) Aldehydes including formaldehyde and acetaldehyde are generated during the manufacturing process of PET, mainly due to its thermal oxidation;(2) Aromatic compounds including benzene and toluene are originated from the disperse dyes. So the degree of dye removing has a great influence on the production safety; (3) Thermal oxidation causes more VOCs than nonoxidative thermal degradation. So in the stages of melt spinning and slightly alcoholysis, usually in O₂ containing atmosphere, devolatilization should be developed further.

Abstract: The degradation of polycarbonate (PC) food contact materials was studied based on analysis with GC-MS, FTIR, UV-Vis and TG techniques. It was evident that the processing temperature of the materials significantly enhanced the release of bisphenol A, an endocrine disruptor. Investigation of the redshift of UV band also revealed that high temperatures accelerated the aging degradation of PC.

Abstract: The thermal degradation of phenolic formaldehyde resins (PF) were studied using thermo gravimetric analysis (TGA). The evolved volatiles during thermal degradation of PF were examined by mass spectrometry (MS). The structure changes of thermal degradation of synthetical phenolic resin (PF_1.2) and commercial resin (CPF) were investigated by solid-state ¹³C nuclear magnetic resonance (¹³C-NMR) techniques. The experimental results show that the degradation process of PF could be separated into three stages. In the first stage, ether bonds and unreacted terminal hydroxymethyl groups of the cured resin degraded. Methylene bridges decomposed into methyl groups then yielded both phenol and cresol homolog in the second stage. In the third stage, cyclodehydration and forming char of phenolic hydroxyl occurred. Our study showed that the main thermal degradation of PF in the second stage is the decomposition reaction of the methylene bridges instead of auto-oxidation of the methylene bridges reported in previous works.

Abstract: This paper is mainly to introduce The Short Message Peer to Peer (SMPP) protocol, and one of it’s major application to Unstructured Supplementary Services Data (USSD). The author intends to utilize SMPP protocol to realize a basic USSD Session flow.

Abstract: Modeling of crystal structure in material science curriculum was practiced and applied to keep it simple and understandable by using MS. The unit cells and atomic configurations are produced to show the theory system of geometry description of crystal structure. Many examples, as diamond, graphite, nanomaterial and advanced carbon materials, are employed to describe the main application of MS in material science teaching. According to these atomic modeling configurations, crystal structures exhibit a clearly and understandable appearance for us. So, the meaning of learning and understanding the related parameters of geometry description of crystal structure was explored with the point which helped students to realize and master the abstract concepts of crystal structure.

Abstract: The morphology of microstructure and PAG was observed by means of LEICA DMIRM metallurgical microscope, the phase was measured by D8 ADVANCE X-ray diffractometer (XRD), and the martensitic transformation point is tested on DIL805A dilatometer after ST. The results show that the PAG size of C250 steel has not a clear growth. The recrystallisation has the priority of nucleation in the PAG boundary. The morphology of martensite presents irregular bans and stringers before recrystallisation, whereas presents blocky thereafter. The intermetallic compounds re-dissolve by ST. With the prolonged of ST time, the Ms point increases before recrystallisation, decreases thereafter; the Mf point does not have a clear change.

Abstract: The alcoholic extract of the Apocynum venentum (AV) bark were purified by silica gel column chromatography. The isolated chemical constituents were identified by MS, NMR, IR spectra. The main chemicals isolated from AV bark were quercetin (1), kaempferol (2), isoquercitrin (3), luteolin (4), hyperoside(5), 7-hydroxy-6-methoxy-2H-1-benzopyran-2-one (6), b-sitosterol (7), stigmasterol (8), 3, 4-dihydroxy-benzoic acid methyl ester (9), 3, 5-dihydroxybenzaldehyde (10) and 3, 4-dihydroxy-benzoic acid (11). The compounds (1)～(6) and (8)～(11) were obtained from AV bark for the first time.