Thermal mixing characteristics of helium gas in high-temperature gas-cooled reactor, (I) thermal mixing behavior of helium gas in HTTR

The future high-temperature gas-cooled reactor (HTGR) is now designed in Japan Atomic Energy Agency. The reactor has many merging points of helium gas with different temperatures. It is needed to clear the thermal mixing characteristics of helium gas at the pipe in the HTGR from the viewpoint of structure integrity and temperature control. Previously, the reactor inlet coolant temperature was controlled lower than specific one in the high-temperature engineering test reactor (HTTR) due to lack of mixing of helium gas in the primary cooling system. Now, the control system is improved to use the calculated bulk temperature of reactor inlet helium gas. In this paper, thermal–hydraulic analysis on the primary cooling system of the HTTR was conducted to clarify the thermal mixing behavior of helium gas. As a result, it was confirmed that the thermal mixing behavior is mainly affected by the aspect ratio of annular flow path, and it is needed to consider the mixing characteristics of helium gas at the piping design of the HTGR.     

Effects of inhibitors on anaerobic microbial consortium with enhanced dechlorination activity in polychlorinated biphenyl mixture

Characterization was carried out on the anaerobic microbial consortium with enhanced degradation activity toward polychlorinated biphenyls in Kanechlor-300 and Kanechlor-400 mixtures in a burnt soil (BS) culture. The addition of molybdate to the BS culture resulted in the accumulation of less-chlorinated biphenyls such as 4,4'-dichlorinated biphenyl and 2,3',4-trichlorinated biphenyl; however, no such accumulation occurred without molybdate supplementation. No significant effect was observed in individual congeners in the BS culture supplemented with 2-bromoethane sulfonic acid. Analyses involving both the polymerase chain reaction-denaturing gradient gel electrophoresis of partial 16S rRNA genes and respiratory quinones showed that the predominant microorganisms in the BS culture were anaerobic Firmicutes, while sulfate reducers of the phyla Deltaproteobacteria, Firmicutes and Chloroflexi were absent in the culture amended with the inhibitors. No positive correlation was observed between the dechlorination activity and a PCR-based detection of gene fragments of known dechlorinating bacteria. These results suggest that sulfate reducers played an important role in the enhanced anaerobic dechlorination of PCBs in the BS culture.     

Carbon nanotube growth from semiconductor nanoparticles

Nanoscale metal catalysts have been indispensable for carbon nanotube (CNT) synthesis by chemical vapor deposition (CVD). We show that even semiconductor nanoparicles of SiC, Ge, and Si produce single-walled and double-walled CNTs in CVD with ethanol. This implies that nanosize structures might act as a template for the formation of CNT caps composed of five- and six-membered rings. Providing a template for cap formation is the essential role of the catalysts.     

Synthesis and properties of bis(sodium sulfonated ester) types of cleavable surfactants derived from 1-O-alkylglycerols

Novel sulfonated ester types of cleavable surfactants were easily prepared by acid-catalyzed esterification of 1-O-alkylglycerols with bromocarboxylic acids, followed by the Strecker reaction. These surfactants have good solubility in water. Though this series of cleavable surfactants are divalent in type, they show good micelle formation and the ability to lower surface tension. The solubility of these surfactants in hard water was more than 10 times higher than sodium 1-dodecanesulfonate. They decompose quickly and completely in 0.5 M NaOD. Their biodegradabilities were higher or almost the same as that of sodium 1-dodecanesulfonate.     

A Lower Irradiation Dose of 308 nm Monochromatic Excimer Light Might Be Sufficient for Vitiligo Treatment: A Novel Insight Gained from In Vitro and In Vivo Analyses

A 308 nm monochromatic excimer light (MEL) is widely used to treat patients with vitiligo. However, dose optimization still needs to be clarified. This study aimed to obtain objective evidence regarding various doses of MEL irradiation, induced cell level changes in vitro, and skin level alterations in vivo. Cultured human keratinocytes were irradiated with MEL using various doses. After irradiation at low doses, stem cell factor, endothelin-1, and glycoprotein nonmetastatic melanoma protein B, factors that activate and protect melanocytes, were found to be significantly elevated in keratinocytes. After irradiation using medium and high doses, inflammatory cytokines were induced. The amount of ATP released and the level of inflammasome activation, which are known to be related to interleukin-1β activation, were also increased. The back skin of guinea pigs and mice were irradiated with MEL at varying doses. After irradiation, an increase of epidermal melanin and epidermal melanocytes was confirmed, using the minimal erythemal dose or less. In rhododendrol-induced leukoderma guinea pigs, a much lower dose of MEL irradiation was effective, when compared with the effective dose for control guinea pigs. Our results suggest that a lower irradiation dose of MEL might be sufficient and more suitable for repigmentation in vitiligo treatment.     

Stabilization of entrapped catalase using photo‐crosslinked resin gel for use in wastewater containing hydrogen peroxide

Catalase immobilized using photo‐crosslinkable resin was applied to treatment of wastewater containing a low concentration of hydrogen peroxide. The structure of photo‐crosslinked resin gel was stable even in the acceleration test of concentrated hydrogen peroxide for a long period. Accordingly, the most important subject of this process was maintaining long term catalase activity. The stabilization of immobilized catalase was investigated by modifying gel carriers with some prepolymers and functional monomers, and adding some stabilizing materials without modification of catalase itself. But these gel carriers did not improve the stability beyond 20%. Addition of Tween 80, polyoxyethylene (5) sorbitan monooleate (hydrophilic/lipophilic balance, HLB: 10.0), to catalase was most effective for maintenance of the activity when the enzyme was immobilized in hydrophilic photo‐crosslinked resin, resulting in 80% of its initial activity. It was assumed that this surfactant did not influence the permeation of hydrogen peroxide into gel, but acted as a stabilizer for catalase in the gel carrier. © 2000 Society of Chemical Industry     

“Nata Puree,” a Novel Food Material for Upgrading Vegetable Powders,Made by Bacterial Cellulose Gel Disintegration in the Presence of (1,3)(1,4)-β-Glucan

Pulverization is a potentially powerful solution for the resource management of surplus- and non-standard agricultural products, maintaining their nutritional values for long and ensuring their homogeneity, whereas their original textures could disappear to narrow the application ranges. Therefore, new technologies should be developed for reconstructing the powders to provide them with new physical characteristics. Herein, we developed a novel food material, nata puree (NP), by nata de coco (bacterial cellulose gel) disintegration with a water-soluble polysaccharide using a household blender. The process worked well with (1,3)(1,4)-β-glucan (BGL) as the polysaccharide, which could be substituted with barley extract. Lichenase treatment of the NP dramatically modified its physical properties, suggesting the importance of the BGL polymeric forms. NP exhibited distinct potato powder and starch binding activities, which would be attributed to its interactions with the cell wall components and a physical capture of powders by the NP network, respectively. NP supplementation into the potato paste improved its firmness and enabled its printable range shift for 3D food printing to a lower powder-concentration. NP also promoted the dispersion of powders in its suspension, and designed gelation could also be successfully performed by the laser irradiation of an NP suspension containing dispersed curdlan and turmeric powders. Therefore, NP could be applied as a powder modifier to a wide range of products in both conventional cooking, food manufacturing, and next generation processes such as 3D food printing.