Experimental study of size effect on quasi-static strengths for short glass fibre-reinforced plastics

The present paper examines size effect on the strength of short glass fibre-reinforced phenolic resin (SGP) composites made by press moulding with different loading modes and specimen shapes. Three- and four-point flexural tests and tension–torsion combined tests were conducted at room temperature in order to evaluate the influence of V_f and loading mode on fracture strength. The obtained uniaxial strength data were analysed using the Weibull statistical theory. The relationship between fracture strength and effective volume was investigated based on the Weibull statistical theory and agreed well with the effective volume theory (EVT), regardless of specimen size, dimensions or loading mode. The experimental results revealed that the tension–torsion multiaxial SGP strength was in agreement with the Tsai–Hill failure criterion. The EVT was also applied to the Tsai–Hill failure criterion to consider the size effect, and the validity of the proposed method was confirmed experimentally.     

Formation of poly(vinyl alcohol)–iodine complex in aqueous solution: a SEM study of the freeze-dried substances

The freeze-dried samples prepared from dilute PVA aqueous solutions and PVA–iodine complex aqueous solutions have been examined using a scanning electron microscope. The samples prepared from syndiotacticity-rich PVA (S-PVA) solutions were found to have a network structure due to the formation of intermolecular hydrogen bonds, whereas in the case of atactic PVA (A-PVA) a network structure was not found. The network structure became more finely structured with increasing syndiotacticity. The structure of the freeze-dried sample of the complex solution prepared from S-PVA having a syndiotactic diad content of 63·8%, and iodine, was coarse in comparison with that of the freezedried sample of the S-PVA solution. In addition, the formation of spherical bulges, which are considered to correspond to microgels in the aqueous solution, were observed in several places. In the S-PVA having a syndiotactic diad content of 57·8%, the spherical bulges were not observed, whereas the absorbance of the aqueous solution was the highest. Although A-PVA did not form a PVA– iodine complex at 30°C in solution, the frozen solution turned blue due to the formation of aggregates. These phenomena were confirmed by the degree of crystallinity estimated from IR spectra, and the amount of iodine estimated from X-ray microanalysis of the freeze-dried samples. The PVA–iodine complexes are formed by the interaction of the aggregates of PVA molecules with iodine molecules. However, the PVA microgels do not interact with iodine. © 1998 Society of Chemical Industry     

Current reduction method for dual active bridge converter in nonlinear dead‐time compensation method

This paper proposes a control method for a dual active bridge (DAB) converter, which achieves both a reduction in the nonlinear transmission power error due to the dead‐time and a reduction in the inductor current with a three‐level operation. The nonlinear transmission power error is compensated by designing a zero current period in the inductor current with the three‐level operation. In addition, an inductor current reduction method for the three‐level operation is also proposed. In the nonlinear transmission power error compensation method, the inductor current is reduced by suppressing the circulating current by considering the zero‐current period to be the dead‐time. The validity of the proposed method is confirmed using a 2.0‐kW prototype. The experimental results show that the transmission power error is reduced by up to 85.1%. In addition, the inductor current is reduced by up to 64.1% and the loss is reduced by up to 58.6%. Moreover, the DC offset is eliminated by utilizing the voltage polarity reverse phenomenon in the voltage control.     

Functions of Breast Cancer Predisposition Genes: Implications for Clinical Management

Approximately 5–10% of all breast cancer (BC) cases are caused by germline pathogenic variants (GPVs) in various cancer predisposition genes (CPGs). The most common contributors to hereditary BC are BRCA1 and BRCA2, which are associated with hereditary breast and ovarian cancer (HBOC). ATM, BARD1, CHEK2, PALB2, RAD51C, and RAD51D have also been recognized as CPGs with a high to moderate risk of BC. Primary and secondary cancer prevention strategies have been established for HBOC patients; however, optimal preventive strategies for most hereditary BCs have not yet been established. Most BC-associated CPGs participate in DNA damage repair pathways and cell cycle checkpoint mechanisms, and function jointly in such cascades; therefore, a fundamental understanding of the disease drivers in such cascades can facilitate the accurate estimation of the genetic risk of developing BC and the selection of appropriate preventive and therapeutic strategies to manage hereditary BCs. Herein, we review the functions of key BC-associated CPGs and strategies for the clinical management in individuals harboring the GPVs of such genes.     

Management conditions during dialysis therapy influence the occurrence of complications after renal transplantation?

We investigated whether the management condition of patients during dialysis therapy has an influence on the occurrence of complications after renal transplantation. Thirty-one patients who underwent renal transplantation were investigated: thirteen received kidneys from living related donors and 18 received cadaveric transplants. The relations between weight gain ratio, cardiothoracic ratio (CTR) and blood pressure during dialysis and the rate of episodes of acute rejection or infection after renal transplantation were analyzed. The rate of acute rejection tended to be higher among patients whose CTR was less than 45% than in those whose CTR was 45% or more. There was no relation found between the rate of infection after transplantation and weight gain ratio. CTR, or blood pressure during dialysis therapy. These results suggest the possibility that the management condition of patients during dialysis therapy influences the rate of acute rejection after these patients undergo renal transplantation.     

Method for the simultaneous assay of diacetyl and acetoin in the presence of alpha-acetolactate: application in determining the kinetic parameters for the decomposition of alpha-acetolactate

A simultaneous assay method for diacetyl and acetoin was developed to investigate the formation of diacetyl during the brewing of alcoholic beverages. A GC-MS analysis after the extraction from neutralized sample by ethyl acetate gave accurate assay results. The detection limit was below 0.1 mg/l and the assay was quantitative from 0.1 to 100 mg/l for both compounds. Unlike other methods, the assay results were unaffected by the presence of alpha-acetolactate (up to 26 mg/l), which easily decomposes to diacetyl or acetoin, because the extraction condition prevents the decomposition and extraction of this acidic compound. Since our assay is compatible with samples that contain alpha-acetolactate, the kinetic parameters for decomposition of alpha-acetolactate to diacetyl and acetoin were determined. The decomposition rate constants were affected by the ethanol concentration. Overall kinetics for the decomposition of alpha-acetolactate was formulated as a function of ethanol concentration, pH and temperature. The kinetics can be applied to alcoholic beverages such as sake.     

Influence of Syndiotacticity on Poly(vinyl alcohol)–Iodine Complex Formation

The extent of colour development in an aqueous poly(vinyl alcohol) (PVA)–iodine complex solution increased with increasing syndiotacticity up to a certain syndiotactic content, then decreased with increasing syndiotacticity. The complex formation depended on the content of the syndiotactic pentad sequence length in the PVA molecules. The most suitable content of the syndiotactic pentad for forming complexes was around 12% in the case of reaction at 30°C. A 0·5% solution of syndiotactic PVA (S-PVA) with an syndiotactic diad (s-(diad)) content of 63·8% changed into a sol, whereas that with an s-(diad) content of 58% did not change after standing for 2h at 30°C, and the colour due to the iodine complex in the latter was deeper than in the former. The gel prepared from the 0·5% solution of S-PVA with an s-(diad) content of 63·8% was hardly coloured. In the solutions containing two kinds of s-PVA having different syndiotacticities, additivity for the extent of colour development did not hold, and the extent was lower than the sum of that of the components. The decrease in the extent of colour development at higher syndiotacticity was due to the formation of microgels. The absorption maximum shifted to a longer wavelength with increasing syndiotacticity. The length of polyiodine increased with increasing syndiotacticity. © of SCI.     

Air contamination effects on the compatibility of liquid lithium with molybdenum; TZM,niobium, stainless steels,nickel and hastelloy N in stainless-steel vessels at 600°c

The effects of nonmetallic impurities on the compatibility of liquid lithium with molybdenum, TZM, niobium, type 304 and type 316 stainless steels, nickel and Hastelloy N were investigated. Three compatibility tests (test I, test II and test III), classified by the grade of air contamination of the lithium, were conducted at 600°C for about 1000 h in stainless-steel vessels. In each test the above-mentioned specimens were immersed together in the lithium. In test I weight gain was observed for all the specimens except nickel and Hastelloy N. However, in test II and test III, weight loss was observed for all the specimens. MoNi₃ was produced on the surface of the molybdenum and TZM specimens as a result of the reaction between molybdenum and nickel dissolved in the liquid lithium. NbN_0.9O_0.1 was observed on the surface of niobium specimens in test I and test II, and Nb₂N in test II and test III. The surface of the stainless-steel specimens in test II and test III was depleted with nickel and chromium elements, and deteriorated. The corrosion rates of the test specimens in test III were about 2, 5, 26 and 22 μm/yr for molybdenum or TZM, niobium, type 304 stainless steel and type 316, respectively. Nickel and Hastelloy N were severely attacked by liquid lithium at 600°C. These results were obtained for liquid lithium with a high nickel concentration.