苯乳酸抑制链格孢霉作用靶位的分析

以从自然腐败的樱桃上分离的链格孢霉（Alternaria sp.）LD3.0086为指示菌，研究苯乳酸对链格孢霉的主要抑制作用靶位。应用分光光度法测定苯乳酸对链格孢霉的最小抑菌浓度，通过卡尔科弗卢尔荧光增白剂染液（calcofluor white，CFW）染色观察苯乳酸对菌丝顶端生长的破坏作用，利用扫描电子显微镜和透射电子显微镜观察链格孢霉的超微结构变化，通过测定苯乳酸作用前后链格孢霉上清液中N-乙酰葡萄糖胺质量浓度变化研究苯乳酸对菌丝细胞壁的破坏作用，应用荧光双染色法观察苯乳酸对链格孢霉菌丝细胞膜的损伤作用。结果表明，12.5 mmol/L的苯乳酸能有效抑制链格孢霉的生长；与对照组（无菌水处理）相比，苯乳酸处理后链格孢霉顶端生长细胞无明显形变，经12.5 mmol/L苯乳酸处理的链格孢霉上清液中N-乙酰葡萄糖胺质量浓度基本不变；苯乳酸处理24 h，链格孢霉菌丝细胞壁表面无明显损伤，细胞内结构发生明显变化；苯乳酸短时间（4 h）处理链格孢霉，菌丝细胞膜仍较为完整，加入苯乳酸较长时间（8 h）后细胞膜发生破裂。综合分析可知，苯乳酸对链格孢霉的主要作用靶位应不是菌丝体的细胞壁和细胞膜，而是在菌丝体内部，通过破坏菌丝内部细胞器结构或引起细胞内的生化反应，从而抑制链格孢霉的生长和繁殖，发挥抑菌活性。     

新鲜蒜黄香气活性成分分析鉴定

为分析鉴定新鲜蒜黄的香气活性成分,将新鲜蒜黄加水和二氯甲烷匀浆后进行溶剂辅助蒸发处理,获得风味萃取物。风味萃取物采用气-质联机分析检测出39个挥发性化合物,采用稀释法/气相色谱-嗅闻分析检测出35个气味活性区。根据质谱、保留指数、嗅闻的气味、相关文献,鉴定出35个香气活性化合物,其中3-乙烯基-1,2-二硫环己-4-烯、2-乙烯基噻吩、2,3-二甲基噻吩、二甲基三硫醚、二烯丙基二硫醚、1-氧-4,6-二氧杂环辛烷-5-硫酮、2-甲基二氢-3(2H)噻吩酮具有极高稀释因子(log₃FD ≥ 6),表明对新鲜蒜黄风味贡献大。本实验样品处理条件温和,最大化保持了新鲜蒜黄的风味,研究结果可为蒜黄的贮藏加工及开发利用提供指导。     

预熟化对谷物煮制时间及营养成分影响研究

拟开发大米、小米、玉米、藜麦4种谷物预熟化的工艺路线,使用水浴加热方式对4种谷物进行处理。以各谷物的煮制时间、淀粉、还原性糖、蛋白质的含量作为评价指标,采用控制变量法对此工艺条件进行优化,谷物按直接干燥和-20℃冷冻后干燥两种方式进行处理,结果表明,大米预熟化较佳的工艺路线为:浸泡米水质量比1∶3,在80℃下水浴2 h,经-20℃冷冻后干燥,煮制时间为4 min。小米预熟化较佳的工艺路线为:浸泡米水质量比1∶2,在60℃下水浴2 h,经-20℃冷冻后干燥,煮制时间为3 min。玉米预熟化较佳的工艺路线为:浸泡米水质量比1∶3,在60℃下水浴2 h,经-20℃冷冻后干燥,煮制时间为4 min。藜麦预熟化较佳的工艺路线为:浸泡米水质量比为1∶2,在80℃水浴下加热3 h,经-20℃冷冻后干燥,煮制时间为3 min。     

Characterisation of physicochemical properties,flavour components and microbial community in Chinese Guojing roasted sesame-like flavour Daqu

Daqu is a saccharifying and fermentation agent for Baijiu production. It provides ingredients, flavours or flavour precursors, microorganisms and enzymes that influence Baijiu quality and character. Here, a systematic investigation was performed on the physicochemical properties, volatile flavour compounds and microbial community structures of Chinese Guojing roasted sesame-like flavour Daqu. The results show that the Daqu exhibited high saccharifying ability, but low liquefying and fermenting ability. Analysis by headspace solid-phase microextraction gas chromatography–mass spectrometry showed that the Daqu and a simulated solid-state fermentation sample contained 28 and 49 volatile components, including alcohols, esters, aldehydes, benzodiazepines, alkenes and nitrogen containing compounds. The main volatiles were aldehydes, esters and alcohols in Daqu, while the esters, alcohols and phenols were relatively higher in the solid-state fermentation sample. With the microbial flora, Bacillus, Actinobacteria_norank, Thermoactinomyces, Enterobacteriaceae_norank, Enterobacter, Actinopolyspora, Kroppenstedtia, Pseudomonas and Sphingobium were the main prokaryotic microorganisms. The dominant fungi were Thermomucor, Trichocomaceae_Incertae Sedis, Absidia, Eurotiomycetes_Incertae Sedis, Mucorales_Incertae Sedis and Eurotiales_Incertae Sedis. By systematically characterising the physicochemical properties, flavour compounds and microorganisms in Daqu, this study increases the understanding of Daqu and provides information for improvements in Baijiu production and quality. © 2019 The Institute of Brewing & Distilling     

微波等离子体原子发射光谱法(MP-AES)测定出口营养强化剂中十种元素

建立了一种微波等离子体原子发射光谱(MP-AES)测定出口营养强化剂中元素快速分析的方法,测定了八种石家庄辖区出口营养强化剂中Zn、Cd、Cu、Ni、Fe、Pb、Mn、V、Al、Cr十种元素的含量。实验结果表明,样品测定值均满足试验要求,各元素标准曲线线性良好,线性相关系数R2≥0.999,加标回收率在80.00%~115.00%之间,相对标准偏差(RSD)小于5%。且MP-AES法使用氮气作为助燃气,比传统方法安全经济。该方法可一次测定十种元素,精密度及回收率良好、经济、快捷,可作为营养强化剂元素快速分析方法。     

并联有源滤波器的改进重复控制策略研究

针对三相整流负载产生的6k±1次谐波,提出静止坐标系下的改进型6k±1重复控制策略。同时将比例控制与改进型重复控制相结合,设计改进重复控制并联比例的复合控制结构。为减小改进重复控制中延时环节不为整数的影响,采用基于Lagrange插值近似的FIR滤波器逼近分数延时特性。最后对系统进行稳定性分析和详细设计方法进行推导。通过Matlab仿真验证改进重复控制策略能有效跟踪6k±1次谐波且具有良好的补偿效果,动态响应较快。     

Hypoxia induced apoptosis of rat gastric mucosal cells by activating autophagy through HIF-1α/TERT/mTORC1 pathway

The pathogenesis of high altitude-related gastric mucosal injury remains poorly understood, this study aimed to investigate the role of autophagy in hypoxia-induced apoptosis of rat gastric mucosal cells. Rats were randomized into four groups which were maintained at an altitude of 400 m (P) or received no treatment (H), autophagy inducer rapamycin (H+AI) or autophagy inhibitor 3-MA (H+AB) at an altitude of 4,300 m for 1, 7, 14 and 21 days, respectively, and the morphology, ultrastructure, autophagy, and apoptosis of gastric mucosal tissues were examined. Gastric mucosal epithelial cells CC-R039 were cultured under conditions of normoxia, 2% O2 (hypoxia), or 2% O2+anti-mTORC1 for 0, 24, 48, and 72 h, respectively, and the autophagy and apoptosis were analyzed. CC-R039 cells were transfected with siHIF-1α, siTERT, or siRNA and the autophagy was examined. The results showed that the exposure to hypoxia increased the autophagy and apoptosis of gastric mucosal cells in rats, and apoptosis was aggravated by rapamycin treatment but alleviated by 3-MA treatment. Increased duration of hypoxia from 0 to 72 h could increase the autophagy and apoptosis but decrease the proliferation of gastric mucosal cells. Inhibition of mTORC1 with rapamycin led to further increase in apoptosis and even substantial cell death, and inhibition of HIF- 1α and TERT increased mTORC1 expression and reduced autophagy. Moreover, the inhibition of HIF-1α reduced TERT expression. In conclusion, hypoxia could induce apoptosis of rat gastric mucosal cells by activating autophagy through HIF-1α/TERT/mTORC1 pathway     

Enhanced performance of Ni catalysts supported on ZrO2 nanosheets for CO2 methanation: Effects of support morphology and chelating ligands

A series of Ni/ZrO₂ catalysts was prepared by the impregnation method with modification of the morphology of ZrO₂ support as well as the impregnation procedure and tested for CO₂ methanation. The catalysts supported on the ZrO₂ nanosheets displayed superior catalytic performance as compared with that on ZrO₂ nanoparticles, which could be mainly attributed to the abundant oxygen vacancies promoting the adsorption and dissociation of CO₂ molecules as well as the high dispersion of Ni species. With the introduction of ethylenediamine (En) in the impregnation procedure, the resulting Ni-15En/ZrO₂-1.5 catalyst showed the optimal activity with CO₂ conversion of 86% significantly higher than Ni/ZrO₂-0 of 44% and Ni/ZrO₂-1.5 of 79% at 0.5 MPa and 300 °C. The excellent performance was attributed to increased moderately basic sites for CO₂ adsorption in ZrO₂ nanosheets, as well as the enhanced dispersion of nickel caused by the complexation of Ni ions with En, which inhibited the aggregation of nickel particles in the subsequent thermal treatments. In conclusion, the synergistic effects of the morphology of ZrO₂ nanosheets as well as the chelating behavior of En contributed to the enhanced performance of Ni-15En/ZrO₂-1.5 in the CO₂ methanation reaction. The strategy shows good prospects for controlling the size of active metals, especially those that were dispersed on the surface of the two-dimensional (2D) metal oxide materials.