Assessing the viability of three Lactobacillus bacterial species protected in the cryoprotectants containing whey and maltodextrin during freeze-drying process.

Freeze-drying of bacteria associates with different stresses such as osmotic pressure, temperature and oxidation, and decreases bacterial viability, which seem to reduce by applying cryoprotectants. The present study evaluated the effect of four cryoprotectants on decreasing the stress caused by freeze-drying process among three Lactobacillus species. Additionally, it highlighted the use of whey and maltodextrin as a substitute for peptone and sucrose in cryoprotectants respectively. The viability of lactobacilli was measured after freeze-drying, 1 month of storage at 25 and 4°C. Based on the results, the viability rate of bacteria in protectants during freeze-drying stage was dependent on their strains. The best viability of Lacticaseibacillus rhamnosus GG and Ligilactobacillus salivarius 20687 was, respectively, observed in the protectants containing sucrose and whey, while Lactiplantibacillus plantarum NRRL B-14768 viability was equal in all protectants. The number of live bacteria reduced significantly by storing bacteria for 1 month at 25°C compared to the 4°C storage. During the storage period, the viability of L. salivarius improved by adding sucrose in protectant. Due to the positive effect of whey and sucrose in the drying and storage stage, on bacterial viability, the protectant consisting of whey and sucrose is suggested for all of the species under study.

Proton-irradiation-immune electronics implemented with two-dimensional charge-density-wave devices.

We demonstrate that charge-density-wave devices with quasi-two-dimensional 1T-TaS2 channels show remarkable immunity to bombardment with 1.8 MeV protons to a fluence of at least 1014 H+cm-2. The current-voltage characteristics of these devices do not change as a result of proton irradiation, in striking contrast to most conventional semiconductor devices or other two-dimensional devices. Only negligible changes are found in the low-frequency noise spectra. The radiation immunity of these "all-metallic" charge-density-wave devices is attributed to the quasi-2D nature of the electron transport in the nanoscale-thickness channel, high concentration of charge carriers in the utilized charge-density-wave phases, and two-dimensional device design. Such devices, capable of operating over a wide temperature range, can constitute a crucial segment of future electronics for space, particle accelerator and other radiation environments.

Effect of vitamins A, E, C and omega-3 fatty acids supplementation on the level of catalase and superoxide dismutase activities in streptozotocin-induced diabetic rats.

BACKGROUND: Since free radicals and antioxidant enzymes may play an important role in the development of diabetes, the present study was designed to assess the effect of supplementation with vitamins A, E and C and ω-3 fatty acids on catalase and superoxide dismutase activity in streptozotocin (STZ)-induced diabetic rats. METHODS: A total of 64 male Wistar rats weighing 250 g were divided into four groups as normal control, diabetic control, diabetic supplemented with vitamin A, E and C and diabetic supplemented with ω-3 fatty acids. After four weeks the rats were anesthetized and catalase (CAT) and superoxide dismutase (SOD) activities were investigated in blood samples, liver and heart homogenates. RESULTS: In diabetic rats, the activity levels of heart SOD (p < 0.001) and heart and liver CAT (p < 0.001) were significantly lower than in normal control rats. Supplementation with vitamins A, E and C significantly increased heart CAT (p = 0.05). No significant change was observed in diabetic rats supplemented with ω-3 fatty acids. CONCLUSION: Supplementation with vitamins A, E and C and ω-3 fatty acids was found to increase heart CAT activity in diabetic rats and they can be valuable candidates in the treatment of the complications of diabetes (Tab. 6, Ref. 26).