Flash Lamps as Ignition and Initiation Sources of the VS-2 Pyrotechnic Composition

In the present work it is found that the pyrotechnic composition VS-2 can be initiated with flash lamps IFC-500 and EVIS. VS-2 pyrotechnic composition contains 90% of mercury（Ⅱ） 5-hydrazinotetrazolate perchlorate and 10% of optically transparent copolymer of 2-methyl-5-vinyltetrazole and methacrylic acid （PVMT）. We have found that the flash lamps make it possible to initiate combustion of VS-2 composition with its transition to detonation both in cylindrical charges placed in brass caps of 5 mm diameter and 2 mm high， and film charges with 10 mm×80 mm in size and surface weights of 60 mg·cm^-2 and 90 mg·cm^-2， showing ignition delay times 10 μs and 3 μs， respectively. We also measured detonation velocities for VS-2 composition film charges， which were 4375-4505 m·s^-1 （of the charge being surface mass 60 mg·cm^-2） and 4221-4281 m·s^-1 （of the charge being surface mass 90 mg·cm^-2） and their blasting action on the aluminum plate. The depths of the normal shock wave imprints at the charge-barrier interface were 0.6-0.7 mm （for surface mass of the film charges 60 mg·cm^-2） and 1.2-1.3 mm （for surface mass of the film charges 90 mg·cm^-2）.     

海蜇Ⅰ型胶原蛋白的提取及结构特性研究

以海蜇为原料，采用盐酸-胃蛋白酶法提取胶原蛋白，并通过聚丙烯酰胺凝胶电泳（SDS-Polyacrylamide gel electrophoresis，SDS-PAGE）、紫外光谱（UV-visible spectroscopy，UV）、氨基酸分析、红外光谱（Fourier-transform infrared spectroscopy，FTIR）、圆二色谱（Circular dichroism，CD）以及扫描电镜（Scanning electron microscope，SEM）对其结构特性进行了系统全面的研究。结果显示，海蜇胶原蛋白在135 kDa左右有一条α-链，在245 kDa以上有一条β-链和γ-链，紫外吸收峰在233 nm处，符合I型胶原蛋白的特征，其亚基组成可能为[α₁(I)]₃。海蜇胶原蛋白中含量最高的氨基酸为甘氨酸，占氨基酸总量的25.99%，且含有15.94%的亚氨基酸。红外光谱和圆二色谱均表明海蜇胶原蛋白分子排布紧凑，具有主要由氢键构成的完整三螺旋结构。扫描电镜结果显示海蜇胶原蛋白具有多层聚集、以纤维为主的无规则网状结构。     

Metaproteomic analysis of enzymatic composition in Baobaoqu fermentation starter for Wuliangye baijiu

Wuliangye is one of the most famous brands of baijiu in China. The typical flavours of Wuliangye baijiu are mainly formed by the multifarious enzymes in fermentation starter (Baobaoqu, BBQ). As the enzymes remained poorly understood, the detailed enzymatic composition of BBQ was analysed by metaproteomics for the first time. It is worth noting that the enzymes from plant, animals and micro-organisms were detected together and oxidoreductases were the dominant enzymes. Next, the analysis of function showed that the enzymes were mainly involved in carbon metabolism and the biosynthesis of amino acids. Additionally, the relationship between differential abundant enzymes and formation of typical flavour substances in premium and normal BBQ was established. Furthermore, the activities of classic enzymes in BBQ were examined to verify the reliability of metaproteomic results. This study will provide clues to further improve the manufacturing technology for Wuliangye baijiu.     

Real-time organic aerosol chemical speciation in the indoor environment using extractive electrospray ionization mass spectrometry

Understanding the sources and composition of organic aerosol (OA) in indoor environments requires rapid measurements, since many emissions and processes have short timescales. However, real-time molecular-level OA measurements have not been reported indoors. Here, we present quantitative measurements, at a time resolution of five seconds, of molecular ions corresponding to diverse aerosol-phase species, by applying extractive electrospray ionization mass spectrometry (EESI-MS) to indoor air analysis for the first time, as part of the highly instrumented HOMEChem field study. We demonstrate how the complex spectra of EESI-MS are screened in order to extract chemical information and investigate the possibility of interference from gas-phase semivolatile species. During experiments that simulated the Thanksgiving US holiday meal preparation, EESI-MS quantified multiple species, including fatty acids, carbohydrates, siloxanes, and phthalates. Intercomparisons with Aerosol Mass Spectrometer (AMS) and Scanning Mobility Particle Sizer suggest that EESI-MS quantified a large fraction of OA. Comparisons with FIGAERO-CIMS shows similar signal levels and good correlation, with a range of 100 for the relative sensitivities. Comparisons with SV-TAG for phthalates and with SV-TAG and AMS for total siloxanes also show strong correlation. EESI-MS observations can be used with gas-phase measurements to identify co-emitted gas- and aerosol-phase species, and this is demonstrated using complementary gas-phase PTR-MS observations.     

Modelling and simulation of two-bed PSA process for separating H_2 from methane steam reforming

Methane steam reforming is the main hydrogen production method in the industry. The product of methane steam reforming contains H_2, CH_4, CO and CO_2 and is then purified by pressure swing adsorption(PSA) technology. In this study, a layered two-bed PSA process was designed theoretically to purify H_2 from methane steam reforming off gas. The effects of adsorption pressure, adsorption time and purgeto-feed ratio(P/F ratio) on process performance were investigated to design a PSA process with more than99.95% purity and 80% recovery. Since the feed composition of the PSA process changes with the upstream process, the effect of the feed composition on the process performance was discussed as well.The result showed that the increase of CH_4 concentration, which was the weakest adsorbate, would have a negative impact on product purity.     

Enterococcus faecium AS8及其胞外多糖对发酵乳流变学特性的影响

通过红外光谱、气相色谱-质谱联用和流变仪的检测,探究产自屎肠球菌(Enterococcus faecium)AS8的胞外多糖(exopolysaccharide,EPS)(AS8-EPS)的结构组成和流变性能。采用3种发酵乳作为样品,分别为Streptococcus thermophilus+Lactobacillus bulgaricus、EPS+S. thermophilus+L. bulgaricus和E. faecium AS8。结果表明,在贮藏期间,不同发酵乳样品具有不同的流变学性质。同时,补充添加EPS和原位EPS对发酵乳流变性能具有不同的影响。通过Sephadex G-100和Sephadex G-50的分离纯化,获得2种多糖,分别为AS8-1-EPS和AS8-2-EPS。AS8-1-EPS主要单糖组成为甘露糖、葡萄糖和半乳糖(分别占59.1%、26.8%、7.9%),还有含量很少的其他单糖;AS8-2-EPS主要单糖组成为甘露糖、葡萄糖、半乳糖和鼠李糖(分别占65.4%、21.3%、8.9%、4.4%)。红外光谱检测结果表明AS8-1-EPS和AS8-2-EPS均为杂多糖。     

Screening of frozen-thawed conditions for keeping nutritive compositions and physicochemical characteristics of goat milk

Frozen milk can help producers overcome the seasonality of goat milk production, low goat production and short lactation periods, and avoid discarding milk during some special periods. We investigated effects of combination between freezing (cryogenic refrigerator of ?16 to ?20°C or ultra-cryogenic refrigerator of ?76 to ?80°C) and thawing (homeothermy of 20 to 25°C or refrigeration of 2 to 4°C) on nutritive compositions and physicochemical characteristics of raw goat milk during storage period (80 d). Compared with fresh goat milk, the frozen-thawed milk decreased contents of fat, protein, and lactose, as well as surface tension and stability coefficient, whereas increased effective diameter and polydispersity index. The average values of color values (L*, a*, and b*) in 4 group samples changed from 83.01 to 82.25, ?1.40 to ?1.54, 3.51 to 3.81, respectively, and the ΔE of most samples did not exceed 2. In contrast to the other 3 frozen-thawed treatments, goat milk treated with ultra-cryogenic freezing-homeothermic thawing (UFHT) possessed higher fat (5.20 g/100 g), smaller effective particle diameter (0.32 µm), and the lowest polydispersity index value (0.26). The color and confocal laser scanning microscopy images of UFHT were similar to those of fresh goat milk, illustrating UFHT was the optimal approach to maintain the natural quality of goat milk. Our finding provides a theoretical basis for producers to freeze surplus milk.     

Interplay of the phase and the chemical composition of the powder feedstock on the properties of porous 8YSZ thermal barrier coatings

Some chemical impurities enhance sintering kinetics of ceramic Thermal Barrier Coatings (TBCs) which can cause their premature failure during operation in gas turbine engine by causing reduction in coating’s strain compliance as well as faster bond-coat oxidation due to increased thermal conductivity. Certain chemical impurities are also believed to suppress resistance to tetragonal to monoclinic phase transformation in 8YSZ, which can also be an important factor regarding TBC’s performance. Most of the impurities and some of the monoclinic phase present in the powder feedstocks can survive into the as-sprayed coating. Therefore, there is a general trend towards OEMs requiring the lowest amounts of chemical impurities and the lowest amounts of monoclinic phase in the powder feedstocks. This paper presents a comprehensive investigation aimed at understanding the role and the relative importance of the chemical and phase purities of the powder feedstock for the properties and performance of thick 8YSZ TBCs.     

Composition and structure of arsenic–antimony alloy electrodeposited from acidic chloride solution

AsSb alloy (0.70–95.81 wt.% As) was prepared by electrodeposition in As(III) and Sb(III) contained electrolytes. The influence of electrolyte composition, hydrochloric acid concentration, and temperature on the composition and structure of AsSb deposits was studied. The electroreduction mechanism of As(III) and Sb(III) in hydrochloric acid solution was revealed via thermodynamic analysis. The results show that the increase of H⁺ concentration promotes the reduction of As(III), while the increase of Cl⁻ concentration significantly inhibits the reduction of Sb(III). As a result, the As content in deposits increases gradually with the increase of hydrochloric acid concentration. Simultaneously, the phase structure of AsSb deposits evolves from crystalline to amorphous. When the As content is 24.55–33.75 wt.%, AsSb mixed crystal is obtained. The electrolysis temperature has little effect on the deposits composition, but the structure of deposits evolves from crystalline to amorphous with decreasing the temperature.