Comparative study of laser and TIG welding for application to ITER blanket hydraulic connection

The shield blanket in ITER has an active cooling structure necessitating hydraulic connections to the cooling water manifold. To maintain or replace the blanket, welding the hydraulic connection by remote handling is necessary. Access for the welding is limited in a small hole in the first wall because of spatial constraints related to neutron and heat fluxes. A bore welding tool is required. Laser and TIG welding tools have been developed, and the welding conditions have been optimized for all position welding to horizontally located pipes. Obtained parameters such as the weld heat input, allowable misalignment, the lifetime of the tools, and the amounts of spatter and fumes, are assessed comparatively. Considering additional aspects related to the remote handling compatibility, for example, the optical fiber or power cable handling, the preferable welding technique for the blanket remote maintenance is discussed.     

Enhanced Azidolysis by the Formation of Stable Ser–His Catalytic Dyad in a Glycoside Hydrolase Family 10 Xylanase Mutant

Glycoside hydrolases require carboxyl groups as catalysts for their activity. A retaining xylanase from Streptomyces olivaceoviridis E-86 belonging to glycoside hydrolase family 10 possesses Glu128 and Glu236 that respectively function as acid/base and nucleophile. We previously developed a unique mutant of the retaining xylanase, N127S/E128H, whose deglycosylation is triggered by azide. A crystallographic study reported that the transient formation of a Ser–His catalytic dyad in the reaction cycle possibly reduced the azidolysis reaction. In the present study, we engineered a catalytic dyad with enhanced stability by site-directed mutagenesis and crystallographic study of N127S/E128H. Comparison of the Michaelis complexes of N127S/E128H with pNP-X₂ and with xylopentaose showed that Ser127 could form an alternative hydrogen bond with Thr82, which disrupts the formation of the Ser–His catalytic dyad. The introduction of T82A mutation in N127S/E128H produces an enhanced first-order rate constant (6 times that of N127S/E128H). We confirmed the presence of a stable Ser–His hydrogen bond in the Michaelis complex of the triple mutant, which forms the productive tautomer of His128 that acts as an acid catalyst. Because the glycosyl azide is applicable in the bioconjugation of glycans by using click chemistry, the enzyme-assisted production of the glycosyl azide may contribute to the field of glycobiology.     

Estimation of consequence and damage caused by an organic hydride hydrogen refueling station

Organic hydride hydrogen refueling stations are currently being developed in Japan. For these stations, we estimate the consequence and damage caused by explosions and heat radiation after a hydrogen leak, and the acute toxicity caused by the leakage and dispersion of methylcyclohexane and toluene energy carriers. First, the organic hydride hydrogen refueling station is defined, and an accident scenario for four leak sizes of hydrogen and chemical leak accidents is set. Next, simulations of the blast wave pressure and heat radiation after the hydrogen leak and of atmospheric dispersion for the evaporation after liquid methylcyclohexane and toluene leaks are performed. Probit functions or threshold values are created for each type of effects caused by the explosion, heat and the inhalation effect on humans of toluene acute toxicity. Population data for the area surrounding the station are created in a 10-m mesh. The consequence and damage are estimated for each leak size. The results show that although the explosion and chemical leak affects the area around the refueling station, the effects are small in all of the accident scenarios. In contrast, although the area of the heat effect is limited to inside the refueling station, the burn damage is large, and there is a need for conducting quantitative risk assessment.     

Isolation and characterization of barosensitive mutants of Saccharomyces cerevisiae obtained by UV mutagenesis

Using UV mutagenesis, 2 high-pressure (HP) sensitive (barosensitive) mutants of Saccharomyces cerevisiae were obtained. The HP inactivation of the mutants, as well as their parent strains, followed 1st-order kinetics in the range of 175 to 250 MPa within 600 s. Both mutants showed larger 1st-order inactivation rate constant values or significant loss of viabilities, compared with their parent strains in the pressure range tested. The inactivation rate constant value of one of the mutants was comparable with that of a previously reported highly barosensitive strain, which was generated by deletion of hsp104 in a trehalose deficient strain. The activation volume values of HP inactivation reactions in the 2 mutants were apparently equivalent with those of their parent strains. This suggested that the mutation did not bring drastic volume changes of the key molecules for HP inactivation. Their auxotrophic properties, growth, and ethanol fermentation were identical in mutant and parent strains. The mutants could therefore be useful for fermentations where control by HP processing is desired.     

Combination of Super Chilling and High Carbon Dioxide Concentration Techniques Most Effectively to Preserve Freshness of Shell Eggs during Long-Term Storage

ABSTRACT:  This study was made to examine the combined effects of stored temperature and carbon dioxide atmosphere on shell egg quality. The shell eggs were packed into polyethylene terephthalate/polyethylene (PET/PE) pouches and stored at 0 °C (super chilling), 10 °C, and 20 °C, respectively for 90 d. The atmospheric carbon dioxide concentration was controlled to obtain the 3 concentration levels of high (about 2.0%), medium (about 0.5%), and low (below 0.01%). Changes in Haugh unit (HU) values, weakening of vitelline membranes, and generation of volatiles were analyzed to evaluate the freshness of shell eggs. Results showed that, compared with the other combinations, the technique of super chilling and high carbon dioxide concentration enabled shell eggs to be most effectively stored for 90 d, based on estimations of the statistical significances of differences in HU values, and on maintaining the initial HU values during storage. In addition, the storage of shell eggs using this combination technique was found to significantly prevent the weakening of the vitelline membrane based on the estimations of numbers of eggs without vitelline membrane breakage when eggs broke, and significantly lowered the incidence of hexanal in the yolk from exposure to the gas chromatographic-mass spectrometric analyses of volatiles. Thus, these results confirmed that the combination of super chilling and high carbon dioxide concentration was the most effective technique for preserving shell eggs during a long term of 90 d compared with other combination techniques.     

Joining of carbon fibre-reinforced silicon nitride composites with 72Ag-26Cu-2Ti filler metal

Unidirectionally reinforced carbon fibre/Si₃N₄ matrix composites were joined with 72Ag-26Cu-2Ti filler metal. Joining interfaces were observed by SEM and analysed by energy dispersive spectroscopy. The strength of the joints was evaluated by four-point bending tests. Most of the interfaces of Si₄N₄ matrix/filler metal were firm without cracking and separation. At the interfaces, reaction between the composites and filler metal was limited. Only a concentration of titanium at Si₃N₄ matrix/filler metal interface was confirmed. On the fracture surfaces, many holes left as traces of pull-out of carbon fibres and pulled out fibres could be observed. The maximum joining strength and the average strength, measured by the bending test, were 159 MPa and 107 MPa, respectively. The pull-out process of fibres from the matrix and the reasons for the large scatter in the strength of joints, were discussed. The fibre pull-out behaviour could be related to fibre distribution density at the joining interface.     

Sintering Formation of Low Temperature Phase MnBi and Its Disordering in Mechanical Milling

With X-ray diffraction and DSC analysis, it is found that 4 cycles of sintering at 593 K are necessary for the complete production of the low-temperature phase (LTP) MnBi. The c/a of the fabricated LTP MnBi is 1.4286. Metastable phase MnBip formed in primary sintering stage of LTP MnBi has the similar crystal structure and lattice constant with the quenched high-temperature phase (HTP) Mn1.08Bi. The structural differences between MnBip phase and Mn1.08Bi phase are discussed. The LTP MnBi phase is unstable for strong mechanical milling as Bi appears after milling over 7200 s in the present milling condition. Strains caused by the mechanical attrition are difficult to accumulate in the MnBi crystaIs, and the crystal size of the milled MnBi is only 30 nm before the presence of grains coalescence. The whole milling process can be classified into 3 stages indicated by the structural changes. Based on the structural parameter calculation, the changes of atomic configurations in every stage have been discussed. The existence of Bi equivalent vacancy site is considered to play an important role in the disordering processes of Mn and Bi atoms     

Clinical efficacy of imipenem/cilastatin sodium for respiratory infections in patients with lung cancer

Imipenem/cilastatin sodium (IPM/CS) was administered to 102 patients with respiratory tract infections and lung cancer. Patients with other serious diseases were excluded and a total of 73 patients were enrolled. They were divided into 12 patients who underwent surgery (operated group) and 61 who did not (non-operated group); the latter group included 28 patients treated with anticancer agents or radiation therapy (treated group) and 33 untreated patients (untreated group). IPM/CS was effective in 75% of the patients, both with and without surgery. The drug was effective in 81% of the treated group, although many of the patients had Stage III or more advanced cancer, as well as bronchial occlusion. IPM/CS was also effective in 69% of the untreated group, although many of the patients have serious infections and a PS (Performance Status) of 3 or greater. Thus, IPM/CS treatment achieved good results. Bacteriological studies showed that 3 out of 4 strains in the operated group and 16 out of 18 in the non-operated group were eliminated. Safety was evaluated in all patients. Two patients (2%) experienced side effects and two others (2%) showed abnormal clinical findings, but the symptoms were mild and resolved after discontinuation or completion of therapy. In conclusion, IPM/CS was very effective for treating respiratory infections in patients with lung cancer.     

Beulanalyse wellenförmiger Schalen veränderlicher Dicke

Buckling analysis of wave‐type shells with variable thickness. In this paper, buckling analysis for two wave‐type shells with variable thickness is treated, where the curvatures of the consecutive shell panels are different directions each other. In the derivation of the transfer matrix the minus radiuses of curvature and transfer angles are introduced. The results are given as buckling coefficients and buckling modes.