直链烷基苯工艺技术的发展

详细地叙述了国内外表面活性剂的主要原料——直链烷基苯生产的新工艺和新技术,着重介绍了固体酸催化剂生产工艺的最新进展。列举了大量的数据和资料,为从事直链烷基苯生产的设计人员提供参考。     

TH-06催化剂合成直链烷基苯Ⅱ.催化剂的失活及再生

对直链烷基苯合成过程中ＴＨ－ ０６ 催化剂的失活及再生进行了研究。通过对失活催化剂进行表征发现,导致催化剂失活的原因主要是萘、１ ,４ － 二丁基－ １ ,２ ,３ ,４ － 四氢化萘、１ － 甲基－ ３ － 壬基茚满及１ － 乙基－ ３ － 庚基－ ２ ,３－ 二氢化茚等大分子在催化剂孔道中的积累。失活从晶内开始,然后逐渐向外扩展。经苯反复洗涤再生,催化剂寿命超过１０００ ｈ 。     

乳酸菌发酵蔬菜汁的研究进展

阐述了乳酸菌对发酵蔬菜汁的作用、目前发酵工艺中的一些关键技术及发酵蔬菜汁稳定性和乳酸菌固定化细胞技术的研究进展．     

苹果酸-乳酸发酵细菌乙醇胁迫应答机制研究进展

由乳酸菌引起的苹果酸-乳酸发酵是生产优质葡萄酒的一个重要工艺过程。在这个过程中,乙醇是乳酸菌活性的主要抑制因子,特别是随着全球气候变暖带来的葡萄含糖量的增加,乙醇对乳酸菌的抑制作用越来越成为人们的研究热点。乙醇胁迫使得乳酸菌细胞结构发生变化,影响苹果酸-乳酸发酵的顺利进行。因此,乳酸菌在乙醇胁迫下的生长、代谢对葡萄酒生产是非常重要的。该文对苹果酸-乳酸发酵过程中常见乳酸细菌在乙醇胁迫下的应答机制进行了阐述,为乳酸菌乙醇胁迫耐受性机制的研究和优良菌株的选育提供参考。     

Characterization of lactic acid bacteria isolated from Italian Bella di Cerignola table olives: selection of potential multifunctional starter cultures

Lactic acid bacteria (19 isolates) from Bella di Cerignola Italian table olives were investigated for their technological and probiotic properties for the selection of multifunctional starter cultures for table olives. The bacteria were first identified by phenotyping and genotyping, then characterized for the production of biogenic amines, growth at different pH, NaCl concentrations, and temperatures. The potentiality of the bacteria to have some probiotic properties (antimicrobial activity against foodborne pathogens, survival in low pH and in the presence of bile salts, ability to adhere to the mammalian cells model IPEC-J2) was also investigated. Eighteen of the studied isolates were identified as Lactobacillus plantarum and one as Enterococcus faecalis. All bacteria were able to grow at a range of pH between 4.0 and 10.0 as well as in media supplemented with 2.5 to 7.5% of NaCl and 0.3% bile salts and survived in MRS broth acidified at pH 2.5; moreover, they inhibited significantly Escherichia coli O157:H7. The adhesion to IPEC-J2 cells was in general low to moderate (5.3 to 8.3%); however, 2 isolates of L. plantarum (c16 and c19) showed interesting higher adhesion values (up to 16%). Our results suggest that at least 3 isolates could be possible multifunctional starters for Bella di Cerignola olives: L. plantarum 16 and 19 for mainly their probiotic properties and L. plantarum 10 for mainly its technological characteristics. Practical Application: A functional starter is a microorganism exerting benefits on human health (probiotic) and able to guide a fermentation (starter). The main goal of this article was to select a functional starter for table olives.     

灌喂不同储存期酸奶对主动免疫小鼠免疫功能的影响

观察不同储存期酸奶对新城疫(New Castle Disease,NDV)疫苗主动免疫小鼠免疫功能的影响。四组饲喂基础日粮的雄性小鼠,每组6只,分别灌喂自出厂日期后4℃储存0d(对照组)、3d(E1组)、6d(E2组)和9d的酸奶(E3组),1ml/只(酸奶灌喂前作乳酸菌计数),连续灌喂7d,第8d皮下注射新城疫Ⅰ苗0.2ml/只,继续灌喂10d,第18d处死。测定不同储存期酸奶对NDV主动免疫小鼠肠道sIgA(分泌型免疫球蛋白A)的分泌、血清NDV抗体效价、血清IL-2(白介素-2)水平及脾脏TNF水平的影响。乳酸菌计数结果显示储存期为3d的酸奶中的乳酸菌数较0d增加了656.26%(p<0.01),6d的和9d的分别下降了40.15%(p<0.05)和65.46%(p<0.01)。小鼠实验发现灌喂储存期为3d酸奶的小鼠肠道sIgA水平、血清NDV抗体效价及脾脏TNF(肿瘤坏死因子)水平分别较0d酸奶的对照组升高了8.04%、10.35%和9.70%。血清IL-2水平升高了23.11%(p<0.05)。灌喂储存期为6、9d小鼠的各项免疫指标水平均低于对照组,而且9d组低于6d组。相关性分析发现仅IL-2水平与不同储存期酸奶中乳酸菌数有显著相关性。由此可见,酸奶的储存影响了乳酸菌活菌数,从而影响了酸奶对机体在外源刺激下的免疫功能的增强作用,储存期3d内的酸奶均具有较好的免疫增强作用。     

Investigation of Microbial Communities of Chinese Sourdoughs Using Culture‐Dependent and DGGE Approaches

Sourdough is typically characterized by the complex microbial communities mainly comprising of yeasts and lactic acid bacteria (LAB). The objective of this study was to explore the microbiota of Chinese traditional sourdoughs collected from different areas of China using culture‐dependent and denaturing gradient gel electrophoresis (DGGE) methods. A total of 131 yeasts, 2 molds, and 106 LAB strains were isolated and identified. Based on the culture‐dependent analysis, the populations of yeasts and LAB were at the level of 10⁵ to 10⁷ and 10⁶ to 10⁷ cfu/g, respectively. Similarly, the results of RT‐qPCR showed that the values of total yeasts and LAB populations were in the range of 10⁶ to 10⁷ and 10⁷ to 10⁸ copies/g, respectively. Using culture‐dependent method, a total of 7 yeasts, 2 molds and 7 LAB species were identified. Results showed that Saccharomyces cerevisiae and Lactobacillus plantarum were the predominant species among the yeasts and LAB microflora. Similarly, using PCR‐DGGE approach, 7 yeasts, 1 mold and 9 LAB species were detected. The yeast, S. cerevisiae, represented the predominant, while the yeast Candida tropicalis represented the subdominant species of the yeast community. Among the LAB community, Lactobacillus sanfranciscensis was the predominant species, while Lactococcus qarvieae, Enterococcus faecium, Lactobacillus delbrueckii and Enterococcus cecorum were among the less dominant species.     

基于多特征与改进霍夫森林的行人检测方法

针对自然背景下的行人检测问题,提出一种多特征与霍夫森林结合的行人检测算法。在特征提取阶段,分别采用梯度方向直方图、局部二值模式和LAB颜色空间来提取行人的梯度、纹理和颜色频率特征,构成丰富的特征集来描述行人;采用霍夫森林算法来创建分类器,对其投票方式进行改进,提出一种基于高斯模板的区域加权投票方式,提高了检测精度。实验结果表明,该算法在误检率FPPW为10-4时,检测率为90.12％, ROC曲线性能上优于 HOG＋SVM 与原霍夫森林算法。     

基于LAB颜色空间的图像阴影检测与去除方法

为实现单幅图像快速去阴影处理，提出基于LAB颜色空间的图像阴影检测与去除方法。首先，将RGB图像转换成LAB图像，再对阴影图像进行边缘检测。然后，通过对不同颜色通道进行分析、计算及重新整合，得到阴影区域与非阴影区域平均色度值相匹配的图像。最后，对图像进行色度校正和边缘校正，实现单幅图像去阴影处理。为验证本文方法的可行性和有效性，分别采用峰值信噪比（PSNR）和结构相似度（SSIM）这2种性能指标，来客观评价图像的去阴影结果，并与2种典型的图像去阴影方法进行比较。结果表明，本文方法的各性能指标最高，如：在3组实验中，PSNR分别达到17.4721、17.6206、17.3048，SSIM分别达到0.8192、0.8344、0.8027。而且去阴影后图像特征信息清晰，保留的结构信息更接近于真实无阴影场景图像，整体取得了很好的去阴影效果。     

A novel bacteriocin against Staphylococcus aureus from Lactobacillus paracasei isolated from Yunnan traditional fermented yogurt: Purification,antibacterial characterization,and antibiofilm activity

Staphylococcus aureus and its biofilm have emerged as a significant threat to the safety of dairy products. In recent years, lactic acid bacteria (LAB) bacteriocins have been widely acknowledged as the potential natural antibacterial substance in food biopreservation due to their excellent antibacterial effects. However, few LAB bacteriocins with antibacterial and antibiofilm activity against S. aureus have been reported in dairy products. In the present study, a novel bacteriocin LSX01 of Lactobacillus paracasei LS-6 isolated from a traditional fermented yogurt produced in Yunnan, China, was purified and characterized extensively. The LSX01 possessed a molecular weight of 967.49 Da and an AA sequence of LDQAGISYT. The minimum inhibitory concentration of LSX01 against S. aureus_45 was 16.90 μg/mL, which was close to or lower than the previously reported bacteriocins. The LSX01 exhibited an extensive antimicrobial spectrum against both gram-positive and gram-negative bacteria. Moreover, LSX01 exhibited excellent tolerance to heat and acid-base treatments, and sensitivity to the proteolytic enzymes, such as pepsin and proteinase K. Furthermore, the treatment of S. aureus_45 planktonic cells with LSX01 significantly reduced their metabolic activity and disrupted the cell membrane integrity. Scan electron microscopy results demonstrated that LSX01 induced cytoplasmic content leakage and cell deformation. Additionally, biofilm formation of S. aureus_45 was also significantly inhibited by LSX01. Overall, the results suggested that the novel LAB bacteriocin LSX01 possessed antibacterial activity and antibiofilm activity against S. aureus and, hence, could have potential for improving safety of dairy products.