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991.
Fermentation dynamics of Lactobacillus helveticus H9 revealed by ultra‐performance liquid chromatography quadrupole time‐of‐flight mass spectrometry 下载免费PDF全文
Zhihui Mi Lai‐yu Kwok Jiangang Xue Yuenan Wang Heping Zhang Yongfu Chen 《International Journal of Food Science & Technology》2018,53(6):1442-1451
Lactobacillus (L.) helveticus H9 is a probiotic strain that can produce antihypertensive peptides during milk fermentation. This study analysed the dynamics of skim milk fermentation by L. helveticus H9 by ultra‐performance liquid chromatography coupled to quadrupole time‐of‐flight mass spectrometry (UPLC/Q‐TOF MS). A total of 1992 metabolites were detected from all of the fermented samples in the LC‐MS analysis by multivariate statistical analysis. Metabolites with variable importance in projection (VIP) values ≥2 were considered differentially abundant among samples and were responsible for the unique taste and nutritional and functional qualities of fermented milk. Valine, threonine, l ‐methionine, tyrosine, asparagine and leucine were the predominant amino acids produced during fermentation, and their quantities changed remarkably during the fermentation process. Citric acid and uric acid were the major, and only detectable, organic acids. Some intermediate metabolites, such as N‐acryloylglycine and nicotinamide‐N‐oxide, were also detected. Moreover, certain oligopeptides such as Val‐Leu, Lys‐Gly, Ala‐Glu, Asp‐Ser, Leu‐Pro and Val‐Phe‐Ala were not detected until the middle and late fermentation periods. This study demonstrated dynamic metabolic changes, providing a strong foundation for deciphering the physiological and biochemical mechanisms of the fermentation process. 相似文献
992.
Xue Li Sining Yun Chen Zhang Wen Fang Xinlei Huang Tingting Du 《International Journal of Hydrogen Energy》2018,43(3):1926-1936
Four types of nano-scale transition metal carbides (HfC, SiC, TiC, and WC), used as accelerants in anaerobic digestion (AD) with cattle manure, were investigated through batch experiments under mesophilic conditions (37 ± 1 °C). The AD system with four carbide accelerants showed a higher biogas yield (463–499 mL/g TS), chemical oxygen demand (COD) degradation rate (58.62–78.90%) and total Kjeldahl nitrogen (TKN) concentrations (905.0–1077.0 mg/L) as compared with control check (CK, 294 mL/g TS, 46.99%, 290 mg/L). All of the digestate samples from the AD systems using four carbide accelerants showed not only higher degradation of organic compounds during thermal analysis, but also stronger fertilizer values. The use of transition metal compounds (TMCs) as accelerants in AD can efficiently improve the conversion of waste resources into biogas and fertilizers, which can potentially open new avenues for the use of TMCs in upcoming research on biomass energy. 相似文献
993.
Study on retrogradation of maize starch–flaxseed gum mixture under various storage temperatures 下载免费PDF全文
Meiqin Feng Xue Yang Jian Sun Xinglian Xu Guanghong Zhou 《International Journal of Food Science & Technology》2018,53(5):1287-1293
This study aimed to investigate the effect of flaxseed gum (FG) on the retrogradation of maize starch (MS) gels under different storage temperatures. In this work, MS‐FG gels with 0–0.4% FG were stored under different temperatures (–20, 4 and 20 °C). Under all storage temperatures, the addition of FG inhibited the retrogradation process of MS, suppressed the recrystallisation of starch molecules, reduced the water loss of starch gels and improved the texture of the gels. Among the three storage temperatures, ?20 °C could almost stop the starch retrogradation but leading it results in the hardest gel texture. The retrogradation of MS‐FG gels stored under 4 °C was most serious with the fastest rate of recrystallisation. When stored at 20 °C, the gels had a retrogradation degree that was lower than when they were stored at 4 °C and also had the softest texture. 相似文献
994.
Xue Jun-xiao Sun Chen-yang Cheng Jun-jin Xu Ming-liang Li Ya-fei Yu Shui 《浙江大学学报:C卷英文版》2019,20(9):1175-1184
Frontiers of Information Technology & Electronic Engineering - Visual inspection of wheat growth has been a useful tool for understanding and implementing agricultural techniques and a way to... 相似文献
995.
Supersonic ejectors involve very complex phenomena such as interaction between supersonic and subsonic flows, shock trains, instabilities, which strongly influences the performance of supersonic ejector. In this study, the static pressure distribution along the ejector wall and Mach number distribution along the axis are used to investigate the internal flow field of supersonic ejector. Results indicate that when the back pressure is much less than the critical back pressure, there are two series of shock trains, and the change of the back pressure will not affect the flow field before the effective area section, so the entrainment ratio would remain constant. The second shock train moves further upstream and is combined with the first shock train to form a single shock train as the back pressure rises. When the back pressure is greater than the critical back pressure, the position of the shock train, the static pressure at its upstream and the entrainment ratio, will be affected. The “effective area section” in the mixing tube is obtained. The effective area section position moves downstream with the increase of the primary flow pressure, while it moves upstream with the increase of the secondary flow pressure. The entrainment ratio shows inversely proportional relationship with the effective section position. Besides, the first shock train length increases with the increase of primary flow pressure or secondary flow pressure. The critical back pressure represents direct proportional relationship to the first shock train length. 相似文献
996.
Kun Wang Dian Kai Liu Pan Pan Wu Xue Bin Yu Long Jiu Cheng Jian Guo Zhang 《International Journal of Hydrogen Energy》2018,43(43):19825-19840
As the most popular high-energy explosives, 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo [5.5.0.0.0] dodecane (Simplified as HNIW or CL20) attracts many attentions for improving its detonation appearance in the application. Here we introduce hydrogen-storage compounds into explosives to estimate the possible improved detonation performances by Car-Parrinello molecular dynamics (CPMD) simulation, where we construct lithium amidoborane (LAB) doped CL20 as the initial structure. Almost all the interactions between hydrogen and CL20 appear exothermic properties, which indicate LAB increases the enthalpies of detonation. The results suggest explosive mixed with hydrogen-storage material is possibly a new field of energetic compound. 相似文献
997.
介绍了一种一次性同步搭设的模板支撑系统的安全防护架转换为后续施工砌体与装饰阶段脚手架的技术.通过采用一次性同步搭设技术,较好地解决了施工过程中的架体拉结问题,减少了管理中各种有关问题出现的影响,并减少了施工成本,值得推广应用. 相似文献
998.
渤海海域浅层油气运移新认识与勘探新进展 总被引:4,自引:3,他引:1
浅层新近系是渤海海域油田储量和产量的主要层系。随着勘探程度的提高,大—中型油气田发现的难度也越来越大。基于渤海海域的勘探实践,结合浅层大—中型油田源外成藏的特性,通过分析油气深层运移与浅层富集的耦合关系,明确了古近系烃源层油气初次、二次运移所形成的"汇聚脊"对其上浅层油气富集、聚集的控制作用,并根据输导体系的组合划分出油气汇聚样式。在"汇聚脊"控藏模式的指导下,渤海海域多个构造带的油气勘探都取得突破,获得一系列亿吨级新发现,由此保证了渤海海域浅层规模优质油气储量持续发现,指导后续勘探进展。 相似文献
999.
1000.
自然属性身份和赋予性身份共同构成了大学的身份属性,但"985"、"211"工程等政策实施过程中混淆了分类和分层的问题,令高等教育重点建设政策形成大学的政策赋予性身份,这种身份的暗示作用通过媒体和社会舆论的不断强化放大,而大学的自然属性身份和大学以人才培养质量、科学研究获得身份认同逐渐被忽略和模糊。大学政策赋予性身份在不断被强化中逐渐演变为教育资源配置和大学招生与就业的公平问题,影响了大学良性竞争和有序的发展。应当从弱化政策赋予性身份、强化社会赋予性身份的角度匡正大学的身份,实现大学的公平、有序、健康发展。 相似文献