Search

Beryllium oxide (BeO) is being re-emphasized and utilized in Micro Modular Reactors (MMR) because of its prominent nuclear and high temperature properties in recent years. The implications of the research about effects of neutron irradiation on the microstructure and properties of BeO are significant. This article comprehensively reviews the effects of neutron irradiation on BeO and proposes the maximum permissible neutron doses at different temperatures for BeO without cracks in appearance according to the data in the previous literature. This maximum permissible neutron dose value has important reference significance for the experimental study of BeO. The effects of neutron irradiation on the thermal conductivity and flexural strength of BeO are also discussed. In addition, microstructure evolution of irradiated BeO during post-irradiation annealing is summarized. This review article has important implications for the application of BeO in MMR.

In recent years, beryllium oxide has been widely utilized in multiple compact nuclear reactors as the neutron moderator, the neutron reflector or the matrix material with dispersed nuclear fuels due to its prominent properties. In the past 70 years, beryllium oxide has been studied extensively, but rarely been systematically organized. This article provides a systematic review of the application history, thermal properties, mechanical properties, corrosion behavior and fabrication methods of beryllium oxide. Data from previous literature are extracted and sorted out, and all of these original data are attached as the supplementary material, so that subsequent researchers can utilize this paper as a database for beryllium oxide research in reactor design or simulation analysis, etc. In addition, this review article also attempts to point out the insufficiency of research on beryllium oxide, and the possible key research areas about beryllium oxide in the future.

The nutritional components of Spirulina residue were determined and evaluated. The insoluble dietary fiber was prepared by alkaline acid treatment from algae residue. The swelling capacity, water holding capacity and grease holding capacity were determined. Insoluble dietary fiber was obtained from Spirulina residue after extraction of phycobiliprotein by alkali acid treatment. Its swelling capacity, water retention capacity and oil retention capacity were measured. The adsorption capacity of dietary fiber for sodium cholate and NO2– was studied. The adsorption capacity of sodium cholic acid and NO2- by dietary fiber was researched. The results indicated that algae residue was rich in nutrients, mainly including protein, carbohydrate and water. The content of phosphorus, magnesium and calcium in minerals was the highest. Algae residue was rich in essential amino acids (lysine, valine, leucine and isoleucine) and non essential amino acids (arginine, glutamine and glutamate). The insoluble dietary fiber had a certain water holding capacity, grease holding capacity and swelling capacity, and the adsorption capacity of sodium cholic acid was relatively obvious. In the simulated human gastric fluid environment of pH=2, it had better adsorption on NO2–. This study results will provide a basis for the high value utilization of Spirulina residue.

This article investigated the deformation behavior of nano-polycrystalline beryllium oxide under tensile and compressive stress using the molecular dynamics simulation method. Both the tensile and compressive test results indicate that beryllium oxide breaks mainly along grain boundaries. At low temperature, there is little internal deformation of beryllium oxide grains. When the temperature is above 1473 K, the internal deformation of beryllium oxide grains also occurs, and the phenomenon becomes more obvious with the increase in temperature. This deformation within the grain should be plastic. The flexural strength fracture morphology of beryllium oxide also shows that the fracture mode of beryllium oxide is a brittle fracture at low temperature, while the slip bands appear at 1773 K. This indicates that beryllium oxide, as a ceramic material, can also undergo plastic deformation under high temperature and stress.

With the method of space-flight breeding, a new strain of Spirulina Platensis mutant H11 was cultivated. Active ingredients polyphenols were extracted from Spirulina Platensis with ethanol. The DPPH and ABTS assays were used to detect the antioxidative and free radical-scavenging capacity of polyphenols. The results showed that the total polyphenol contents of wild type and mutant Spirulina Platensis were 59.774 µg/g (dry weight) and 87.881 µg/g (dry weight), respectively. The DPPH scavenging rates (IC50) of wild type and mutant Spirulina Platensis were 8.931 and 2.076 µg/mL, and the ABTS scavenging rates (IC50) of wild type and mutant Spirulina Platensis were 1.292 and 0.355 µg/mL, respectively; the DPPH scavenging rates (IC50) of ascorbic acid, D-α-tocopherol and Trolox were 4.084, 10.309 and 6.452 µg/mL, respectively, and the ABTS scavenging rates (IC50) were correspondingly 0.204, 4.44 and 1.089 µg/mL. The mutant strain showed stronger DPPH and ABTS scavenging capacity than wild type Spirulina Platensis, and the antioxidant effect of mutant Spirulina Platensis was stronger than or close to that of ascorbic acid, D-α-tocopherol and Trolox. [ABSTRACT FROM AUTHOR]

Food-grade phycocyanin was obtained fromSpirulina platensiscultured in seawater-based medium and purified by ammonium sulfate precipitation. The stability of phycocyanin under different conditions, including different pH, temperature, light, and edible stabilizing agents, was systematically investigated by spectroscopy methods. The optimum pH range for phycocyanin was found to be 5.0–6.0. Phycocyanin was kept stable at temperatures up to 45ºC over short time periods (i.e., no significant changes were observed in the relative concentration of phycocyanin, CR). In contrast, incubation at a relatively high temperature resulted in a decrease in the CRand half-life in a temperature-dependent manner. Constant exposure to light at 100 μmol m–2s–1for 36 h, decreased the CRvalue of phycocyanin (pH5.0) to 78.4%. Sodium chloride was an effective stabilizing agent for phycocyanin, and its efficacy increased in a concentration-dependent manner for all concentration ranges assessed in this study. Moreover, phycocyanin exhibited concentration-dependent antioxidant activities in 2,2′-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) and α,α-Diphenyl-β-pricrylhydrazyl assays. Taken together, our results suggest that the optimal conditions for preserving the stability of food-grade phycocyanin isolated fromS. platensisare a pH of 5.0–6.0, low temperature, darkness, and the addition of edible stabilizing agents. [ABSTRACT FROM PUBLISHER]

Botryococcus   braunii , a prestigious energy microalga, has recently received widespread attention because it can secrete large amounts of exopolysaccharides (EPS) with potential applications in food, cosmetics, and nutraceuticals. Unfortunately, the insufficiency of research on the bioactivity and structure-activity relationship of B . braunii EPS has impeded the downstream applications. In the present study, alcohol precipitation, deproteinization, and DEAE-cellulose column chromatography were used to extract and purify B . braunii SCS-1905 EPS. It was found that B . braunii SCS-1905 EPS were high-molecular-weight heteropolysaccharides containing uronic acid (7.43-8.83%), protein (2.30-4.04%), and sulfate groups (1.52-1.95%). Additionally, the EPS primarily comprised galactose (52.34-54.12%), glucose (34.60-35.53%), arabinose (9.41-10.32%), and minor amounts of fucose (1.80-1.99%), with the presence of a pyranose ring linked by a β -configurational glycosidic bond. Notably, the antioxidant activity of crude exopolysaccharides (CEPS) was stronger, and the half maximal inhibitory concentration (IC 50 ) for ABTS and hydroxyl radicals was significantly lower than that of deproteinized exopolysaccharides (DEPS). Overall, this study indicated a potential application of B . braunii SCS-1905 EPS as a natural antioxidant. In summary, B . braunii EPS could be used as a potential feedstock for the production of antioxidant health foods.