榨菜低盐腌制过程的微生物群落结构与动态分析

采用平板菌落计数法及PCR-SSCP(单链构象多态性)方法,分析低盐榨菜腌制过程中微生物群落结构及数量的变化情况;对通过SSCP方法得到的图谱中11条优势条带序列进行比对,结果表明,在榨菜腌制发酵初期,肠膜明串珠菌(Leuconostoc mesenteroides)为主要的优势菌群;随着腌制环境条件的变化,出现植物乳杆菌(Lactobacillus plantarum)和短乳杆菌(Lactobacillus brevis);在腌制保存后期起主导作用的微生物为植物乳杆菌(Lactobacillus plantarum)和Lactobacillus versmoldensis;榨菜腌制保藏过程中pH值始终呈下降趋势,乳酸菌数量经历了一个先急速上升后逐渐趋缓,并稳定在一定数量的过程.对优化条件下制得的不同阶段的高品质低盐腌制榨菜样品进行微生物结构及分布分析,证实了不同乳酸菌的作用.     

机场视觉移动服务机器人的设计与研究

民航事业迅猛发展,加上疫情突现,机场中迫切需要一种无人的机器人移动服务平台,以减少人力劳动和阻断病毒传播;依据机场环境和功能要求,对机场移动服务平台进行模块化设计与搭建;平台集成RGB-D相机系统Kinect 2.0,采用张正友标定原理确定相机内外参数;设计和实现移动平台的视觉SLAM整体架构,利用ORB算法进行图像特征点的提取与匹配,对邻帧图像进行估计与优化;将平台样机投入实验场地,设定粒子数为50,最小匹配得分为30,构建分辨率为每像素0.02m的二维栅格地图和三维点云图;该样机为机场提供一种以视觉传感器为基础的移动服务平台,结合实际需求,其他功能模块能快捷地集成于此,发挥各自的服务作用。     

浅谈中西传统绘画的美学思想差异

由于中西方的宇宙观和哲学背景不同,导致了中西美术的差异。在传统绘画中,形成东西方两大体系,即以中国画为代表的东方绘画和以油画为代表的西方绘画,它们各有自己的基本特征和传统文化的特点,从而形成各自不同的表现形式和审美特点。     

顶部安装钢塔的高层建筑动力特性研究

本文以江苏省电网调度中心为例 ,研究了顶部安装钢结构塔楼的高层建筑整体动力特性 ,给出了整体动力特性的简化计算方法     

稳定奥氏体合金(Ni29Co18余Fe)在含Cl~-水溶液中应力腐蚀开裂特性

本文研究了稳定奥氏体合金(4J29)在中性3.5%NaCl 水溶液中的应力腐蚀特征曲线、起裂方式以及扩展特征;研究了此合金在动态充氢条件下的氢致延滞断裂特性。通过对比分析以及管型试样应力腐蚀结果,提出了此合金在含 Cl~-水溶液中的应力腐蚀是以氢致开裂为主的观点。本文通过对比实验还研究了整体介质中 H~+浓度以及 Cl~-浓度对4J29合金应力腐蚀的影响.     

甲状腺组织的双光子荧光成像

分别对离体新鲜的正常甲状腺组织、结节性甲状腺肿组织以及甲状腺乳头状癌组织进行自体双光子激发荧光(TPEF)和二次谐波(SHG)成像的研究.从双光子图像可知,正常甲状腺组织中滤泡大小较均匀,形态较相似,结节性甲状腺肿滤泡大小不等,而甲状腺癌组织则为大量的实质性癌细胞团结构,结果与标准组织学苏木精一伊红(H＆E)染色图相一致.此外,正常甲状腺组织和结节性甲状腺肿在胶原分布上存在一定差别.研究表明,双光子荧光成像技术可在微观结构上分辨出正常甲状腺组织、结节性甲状腺肿组织以及甲状腺乳头状癌组织的形态学差异,并有望成为甲状腺微创、快速诊断的有效方法.     

基于Newmark积分方案的DDA方法

 不连续变形分析(DDA)方法以离散的块体集合作为研究对象,引入动力学分析和时步积分技术模拟块体系统的不连续变形行为。对DDA采用的常加速度法进行拓展,给出求解块体系统运动方程的Newmark积分格式,并引入一种与块体不平衡力成正比的自适应阻尼使系统收敛到新的平衡状态,保证求解的稳定性。作为考核,将基于Newmark积分方案的DDA方法应用到隧洞开挖模拟,通过和UDEC软件的计算结果进行对比分析,论证改进后DDA方法的有效性和实用性,进一步拓展DDA解决实际工程问题的能力。     

Green tea polyphenols reduce obesity in high‐fat diet‐induced mice by modulating intestinal microbiota composition

In this study, the modulatory effect of green tea polyphenols (GTP) on human intestinal microbiota was investigated. Firstly, germ‐free mice were inoculated with faecal suspension derived from healthy volunteers to obtain human flora‐associated (HFA) mice model. When the high‐fat diet‐induced obese mice model was successfully established, they were randomly divided into high‐fat diet group (HFD) and high‐fat diet group with GTP (HFD‐GTP), and the shifts in relative abundance of the dominant taxa at the phylum, family and genus levels were studied by high‐throughput sequencing. The diversity of the total bacterial community reached the maximum after GTP treatment for 3 weeks, and then decreased when the mice were fed without GTP. Despite interindividual variation, the relative abundance of Bacteroidetes increased from 0.56 ± 0.06 (1st week) to 0.60 ± 0.05 (3th week), while Firmicutes decreased from 0.42 ± 0.06 to 0.37 ± 0.02. Interestingly, certain bacterial communities such as Bacteroidetes and Proteobacteria still increased and Firmicutes showed a decreasing trend when the mice were fed without GTP (4th week). The results showed that GTP benefits the stability of certain gut microbiota, especially in an environment‐triggered microbial imbalance; therefore, it may have prebiotic‐like activity contributing to the prevention of obesity.     

Symbolic Metabolite Analysis of Pickled Wax Gourd in Eastern China by 1H-NMR Spectroscopy and Multivariate Data

Pickled wax gourd is a traditional fermented vegetable product popular in Zhejiang province, eastern China; however, information on their quality is quite limited. In the present study, we investigated the quality of pickled wax gourd at different processing phases using nuclear magnetic resonance, principal component analysis, and orthogonal partial least squares-discriminant analysis. According to the spectra of ¹H NMR, 36 kinds of metabolites were found at the 20th day of fermentation. Principal component analysis score plot showed that diverse marker metabolites occurred in all designated sampling points (every other 5 days), apart from the samples between the 10th day and 15th day of fermentation. Symbolic metabolites at the first 5 days were L-rhamnose, lactate, fatty acid, arginine, N-acetylglutamate, succinate, phosphorylcholine, glutamate, ornithine, lysine, and β-glucose. Lactate, succinate, glycine, proline, and choline were detected at the following period from the 5th to the 10th day of fermentation. Lactate, succinate, glycine, mannitol, choline, and α-ketoglutaric acid were the main metabolites on the 15th and 20th day. The diversity of metabolites fits with the microbial species structure in different pickling periods. This method was proved to be effective for monitoring the pickling process in real time.     

Closed-Form Error Analysis of AF-CARQ with CSI-Assisted Relay over Nakagami-m Fading Channels

This paper presents a new Amplify-and-Forward Cooperative Automatic Repeat reQuest protocol with channel state information-assisted relay which is more suitable for the only-read access networks. The channels of any pair of terminations are quasi static flat Nakagami- \(m\) fading channels, which are mutually independent and non-identically distributed. Assuming that the coherent equal gain combining is adopted to combine the retransmitted signals from the same link at the destination and selective combining is adopted to the signals from different links. Based on the approximation of product of Nakagami- \(m\) variables, we obtain the end-to-end signal-to-noise rate of any link. The closed-form expression of the average bit error rate for several modulation schemes is obtained by analyzing cumulative distribution function (CDF) and Gaussian Q-function. Then we analyze the amount of fading of the fading channels by the \(n\) order moment which is obtained by CDF. Numerical simulation results show that the relay node can resist the fading of system effectively comparing with the system without relay node. And with the increasing of the number of transmission, the performance advantage of relay link is more and more obviously. It is better to let the maximum transmission time \(F=6\) , which is very useful for improving the transmission efficiency of the truncated ARQ system. The maximum reduction of amount of fading can be reached when \(t=3\) , if the total number of transmission is \(f=6\) . The number of bits in the frame should not have too big.