Full penetration welding of thick high tensile strength steel plate with high-power disk laser in low vacuum

This study was undertaken in order to investigate the effect of reduced ambient pressure from an atmospheric pressure (101 kPa) to 0.1 kPa on one-pass full penetration welding of thick high-tensile strength steel plate of 23 mm thickness. A 16 kW disk laser of 1030 nm in wavelength was employed to weld HT980 grade plates at the speed of 5–25 mm/s. In partial penetration welding, it was revealed that humping phenomena occurred easily. Full penetration welding of the high-tensile strength steel plates could not be achieved at 101 kPa. On the other hand, full penetration welding was obtained at the welding speed of less than 20 mm/s at the pressure of less than 10 kPa. Especially, at 0.1 kPa, and 17 and 20 mm/s, sound weld joints without defects were obtained. According to the observation results of a keyhole inlet and a surface molten pool during welding with a high-speed video camera, the melt in front of a keyhole was smaller and the behaviour of a keyhole and a plume was much more stable at 0.1 kPa than at 101 kPa. Moreover, in the full penetration welding, spattering was suppressed under the proper conditions. Such phenomena became more stable in fast welding. It was revealed in laser welding of thick high-tensile strength steel plates that the formation of narrow I-shaped weld beads by achieving full-penetration welding in low vacuum was essential for the production of sound welds without defect.     

Acceptor specificity of trehalose phosphorylase from Thermoanaerobacter brockii: production of novel nonreducing trisaccharide, 6-O-alpha-D-galactopyranosyl trehalose

We investigated the acceptor specificity of a thermostable trehalose phosphorylase from Thermoanaerobacter brockii ATCC 35047 (TbTP) was examined using beta-D-glucose-1-phosphate (beta-G1P) as a glucosyl donor and oligosaccharides as the acceptor. Oligosaccharides with a reducing-end glucose residue as the C-6 substituent (e.g., isomaltose, gentiobiose, melibiose, isomaltotriose, and isopanose) were found to be successful acceptors. The transfer products of isomaltose, gentiobiose, and melibiose were isolated and characterized as 6-O-alpha-D-glucopyranosyl trehalose (alpha-GlcTre), 6-O-beta-D-glucopyranosyl trehalose (beta-GlcTre), and 6-O-alpha-D-galactopyranosyl trehalose (alpha-GalTre), respectively. To produce alpha-GalTre, a novel nonreducing trisaccharide, the reaction conditions of alpha-GalTre were examined using trehalose as a glucosyl donor. As a result, the yield of alpha-GalTre reached 40.5%.     

Synthesis of nickel nanoparticles with excellent thermal stability in micropores of zeolite

Nickel (Ni) nanoparticles were synthesized in micropores of zeolite by the adsorption and decomposition of a sublimated Ni organometallic compound, Ni(C₅H₅)₂, to invent metallic catalysts with nanosize, which are smaller than 5 nm and keep the nanosize at high temperature. In the decomposition process, Ni species were partially decomposed by ultraviolet light irradiation and fixed in zeolite pores prior to thermal reduction under H₂ flow. Note that the Ni nanoparticles showed an excellent thermal stability, because they kept the high dispersion with diameters smaller than 5 nm even after heating at 400 °C. On the other hand, the Ni particles supported on zeolite by a conventional method, which is an incipient wetness impregnation process, became larger than 10 nm after heating at the same temperature. The synthesized Ni nanoparticles acted as a metallic catalyst because they showed higher selectivity for H₂ generation than C₂H₄ generation during ethanol steam reforming reaction.     

Radiocarbon dating and wiggle matching of wooden poles forming circular structures in the 1st Millennium BC at the Mawaki archaeological site,central Japan

Wooden circular structures, presumed archaeologically as a structure related with ritual of ancient people in the Final Jomon period, are specific to archaeological sites excavated mainly in the coastal region around Noto peninsula, central Japan. So far, only few attempts have been made at chronological studies on these wooden structures. ¹⁴C dating has been attempted to wooden poles forming the structures, which had been excavated at the Mawaki archaeological site, Ishikawa prefecture, central Japan, to examine construction period of the structures. It was revealed that these structures were constructed in the Final Jomon period, most probably within 900–400 cal BC. In addition, we have tried wiggle matching of ¹⁴C ages for several annual rings separated from three and two poles that were constituting two circular structures, the oldest and the newest ones. ¹⁴C dates of annual rings measured with AMS were wiggle-matched to IntCal04 data sets by Bayesian statistics. The results indicated that the construction period of these wooden structures can be placed within ca. 820–680 cal BC, being narrowed by about 350 calendar years successfully.     

Thermal Properties of Al-50%Si Alloys

AS FOR Al-Si alloy,this alloy with the characteristicsuch as excellent in a low coefficient of thermalexpansion(CTE),high-heat-conductivity,and wearresistance is used for the piston material of the engine,the heat radiation material,and electronic application1'2.The CTE of the Al-Si alloy decreases further withincreasing Si content because the CTE of Si is low3.The strength and wear resistance of Al-Si alloydecrease with increasing Si content because eutectic Siis coarse grain size an…     

Production of cyclic tetrasaccharide from starch using a novel enzyme system from Bacillus globisporus C11

Production of cyclo[-->6)-alpha-D-Glcp-(1-->3)-alpha-D-Glcp-(1-->6)-alpha-D-Glcp-(1-->3)-alpha-D-Glcp-(1-->] (CTS, cyclic tetrasaccharide) from starch was attempted using 1,6-alpha-glucosyltransferase (6GT) and 1,3-alpha-isomaltosyltransferase (IMT) from Bacillus globisporus C11. The optimal conditions for production from partially hydrolyzed starch were as follows: substrate concentration, 3%; pH 6-7; temperature, 30 degrees C; 6GT, 1 unit/g-dry solid (DS); IMT, 10 units/g-DS. The production of CTS was demonstrated and 544 g of CTS hydrate crystal powders were obtained from 3500 g of partially hydrolyzed starch. Two major by-products were also isolated from the reaction mixture and identified as the branched derivatives of CTSs, 4-O-alpha-D-glucopyranosyl-CTS and 3-O-alpha-isomaltosyl-CTS.     

Acute kidney injury in a postpartum woman with paroxysmal nocturnal hemoglobinuria: A case report and literature review

Paroxysmal nocturnal hemoglobinuria is a rare clonal hematopoietic stem cell disorder characterized by intravascular hemolysis, hemoglobinuria, and inflammatory thrombotic state. Intravascular hemolysis in paroxysmal nocturnal hemoglobinuria (PNH) can lead to acute and chronic renal injury through hemoglobin‐mediated toxicity. A 32‐year‐old pregnant woman with myelodysplastic syndrome was admitted to our hospital with severe preeclampsia. Shortly after an urgent caesarean section, she became obtunded and showed signs of acute kidney injury (AKI) with anuria, severe intravascular hemolysis, and hypermagnesemia. She was diagnosed with PNH with a positive Ham test and flow cytometry analysis. Renal magnetic resonance imaging revealed decreased signal intensity in the renal cortex due to hemosiderin deposition. Hemodialysis, plasma exchange, and administration of corticosteroids ameliorated her clinical condition and renal function. This case illustrates that careful management is required to prevent postpartum AKI in pregnant women with PNH.     

Fabrication of micro-capacitive inclination sensor by resin molding

Capacitive inclination sensors have the advantage that they can easily provide a linear analog output with respect to inclination. Although inclination sensors featuring this advantages are already commercially available, they are generally too large. We fabricated a micro-capacitive inclination sensor by a combination of a resin forming method and a mold. Electrodes of the sensor are 40 μm in a gap and 12 mm² in area. The sensor detects difference of capacitance, which varies with movement of silicone oil accompanying with inclination of the sensor. Since the dimensions of the sensing region are 5 × 5 × 3 mm³ this inclination sensor is expected to be widely used in fields where efficient and reliable position control is a primary factor to be considered. The use of resins is also expected to contribute to a reduction in the costs of materials. We successfully fabricated a micro inclination sensor as a molded product. In future, we will wire up the device to complete this inclination sensor, and will then conduct performance evaluations. If techniques using resin-molded parts are introduced to the low-cost mass-production of Micro Electro Mechanical Systems devices, the range of applications will further expand to new areas of technology and industry.