Lactic acid bacteria (LAB) can take advantage of fermentable carbohydrates to produce lactic acid. They are proverbially applied in industry, agricultural production, animal husbandry, food enterprise, pharmaceutical engineering and some other important fields, which are closely related to human life. For performing the probiotic functions, LAB have to face the low pH environment of the gastrointestinal tract. Therefore, acid resistance of LAB is of great importance not only for their own growth, but also for fermentation and preparation of probiotic products. Recent research studies on acid resistance mechanisms of LAB are mainly focused on neutralization process, biofilm and cell density, proton pump, protection of macromolecules, pre-adaptation and cross-protection, and effect of solutes. In this context, biotechnological strategies such as synthetic biology, genome shuffling, high pressure homogenization and adaptive laboratory evolution were also used to improve the acid resistance of LAB to respond to constantly changing low pH environment.

Face-to-face interfacial assembly of TiO-g-CN hybrid (2D TCN-A) is developed by surfactant-assisted hydrothermal treatment forming a sandwich structure of anatase TiO nanosheets (TiO-A, 5-6 monolayers) and g-CN nanosheets (∼3 monolayers). Post air-annealing is found effective for insertion of oxygen to the hybrid, which remedies the oxygen vacancies of TiO (B) nanosheets and converts it to anatase nanosheets. The enhanced light adsorption, increased donor density, and prolonged life of charge carries are achieved by variation of bandgap and the formation of heterojuction between the two kinds of nanosheets, facilitating separation and transfer of charge carriers. The 2D TCN-A-70 nanosheets show a high photodegradation rate of methyl orange (k ≈ 0.189 min) and photocatalytic evolution rate of hydrogen (18200 μmol g h). This 2D nanosheets hybrid is potentially useful in alleviating environmental and energy issues.

Dielectric polymer materials have received increasing attention in the electronic and electrical industries, however, the miniaturization and intelligent applications of polymer capacitors are limited due to the low energy density....

Abstract.A subacute ruminal acidosis (SARA) model was induced gradually by increasing the proportion of dietary concentrate to evaluate the effect of thiamine supplementation on the structure of bacterial community in dairy cows. Three Holstein dairy cows with rumen cannula were randomly assigned to a replicated 3 · 3 Latin square design trial and received three diets during three successive 21-day periods in each square. The three dietary treatments were as follows: a lowconcentrate diet (control), a high-concentrate SARA-induced diet (SARA) and a high-concentrate SARA-induced diet with 180 mg thiamine/kg DM (SARA+thiamine). Real-time-polymerase chain reaction assay was used to quantify the population variation of SARA-related ruminal bacteria in these cows. The results showed that SARA was induced gradually when cows were fed with the high-concentrate diets. The mean ruminal pH value was higher in the control cows than in those of SARA and SARA+thiamine groups, the mean was decreased in cows fed on SARA diet, and the depression was alleviated by supplemented thiamine and the difference was significant (P < 0.05) especially at 9-h and 12-h sample times (or 1 h and 4 h after the second feeding). The populations of Streptococcus bovis and genus Lactobacillus in cows from the SARA group were increased in log copies/mL by 3.62% and 4.65%, respectively, compared with the control group (P < 0.05). In contrast, in log copies/mL, populations of Butyrivibrio fibrisovens and Megasphaera elsdenii were decreased by 1.14% and 4.90%, respectively (P < 0.05). Thiamine supplementation led to an obvious reduction of Strepococcus bovis and Lactobacillus (P < 0.05), whereas the number of log copies/mL of Megasphaera elsdenii was dramatically increased (P < 0.05). There was no significant effect of thiamine supplementation on the number of log copies/mL of Butyrivibrio fibrisovens and Selenomonas ruminantium (P > 0.05). It was concluded that thiamine supplementation to high-concentrate diets at concentrations of 180 mg/kg DM could help alleviate SARA by increasing rumen pH and balancing the population of lactic acid-producing and -consuming bacteria.