Studies on the light-focusing plastic rod. IX. Chemical composition of the copolymer rod-diethylene glycol bis(allyl carbonate) with 2,2,3,3-tetrafluoropropyl methacrylate

For the preparation of the light-focusing plastic rod (LFR) a gel rod of partially polymerized diethylene glycol bis(allyl carbonate) (CR-39) was immersed in 2,2,3,3-tetrafluoropropyl methacrylate (4FMA) followed by heat treatment under nitrogen. Variations in the chemical composition in this process indicated the following mode of copolymerization: copolymerization of 4FMA with the allylic group in the gel rod occurs to some extent in the immersion process, but a significant amount of either 4FMA or CR-39 remains in the rod. Under heat treatment, these monomers copolymerize to a CR-39–4FMA network copolymer, the preferential component of the LFR. Excellent imaging of the representative LFR is also demonstrated.     

Tensile and impact behavior of drawn polystyrene and high-impact polystyrene

The tensile behaviors of drawn polystyrene (PS) and high-impact polystyrene (HIPS) were examined systematically in the wide range of strain rate, 1.7 × 10^?4–13.1 m/s, without changing the mode of deformation and the shape of the test pieces. It was found for both PS and HIPS that the flexion points of birefringence with increase of draw ratio are intimately correlated with the tensile properties. Especially, the breaking strain and energy of undrawn and drawn HIPS were assigned to the contributions of the following three toughening mechanisms: (a) the generation of large numbers of microcrazes from the equatorial zone of the dispersed rubber particles; (b) the extension of interfacial rubber phase around the circumpolar zone of the dispersed rubber particles and its disintegration from the matrix component; and (c) the shear band formation of the matrix component followed by cold drawing. These mechanisms were discussed in connection with the factors of stress concentration to the rubber particles, hydrostatic pressure effect arising from the difference in Poisson's ratio of rubber and matrix components, and heat generation due to the adiabatic deformation.     

Mechanism of pole‐mounted transformer damage by backflow lightning and measures against the damage on low‐voltage distribution line

Pole‐mounted transformers are especially vulnerable to lightning damage. The progress of the information society imposes increasingly stringent requirements for the reliability of electric power supply, and this in turn necessitates a reduction in lightning damage to pole‐mounted transformers. Lightning protective devices (surge arresters) are now being installed around the primary bushing of the transformers, which has decreased the number of disconnections around the primary bushing due to lightning. But surge arresters installed on the primary side of the transformer cannot protect it against backflow lightning entering the secondary side of the transformer. The characteristic of transformer damage by backflow lightning is that the electromagnetic force produced by the current flowing into the secondary side deforms the transformer windings. This paper elucidates the mechanism of transformer damage by lightning flowing into the secondary side by comparing actual lightning damage cases with the results of verification tests using a short‐circuit generator. Effective countermeasures against transformer damage by backflow lightning are examined by EMTP calculations, which indicate that neutral grounding on the low‐voltage distribution line is the most effective way of decreasing the current flowing into the transformer. The lower the grounding resistance, the less current flows into the transformer. In addition, decreasing the voltage on the secondary side is important in order to protect the secondary‐side bushing. The calculation results indicate that surge arresters installed around the secondary side of the transformer are effective in decreasing the voltage on the secondary side. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(2): 1–11, 2010; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20921     

EXTRACTION OF NEPTUNIUM WITH DI-ISODECYL PHOSPHORIC ACID FROM NITRIC ACID SOLUTION CONTAINING HYDROGEN PEROXIDE

Extraction of Np with di-isodecyl phosphoric acid (DIDPA) from HN03 solution containing H₂O_2> was studied from the aspect of the extraction mechanism and the enhancement of the extraction rate. Neptunium initially in the pentavalent oxidation state can be extracted into DIDPA even without any redox agents, but the extraction rate is rather slow. In the present work, H₂O₂ was found to accelerate the extraction. The rate was almost proportional to the 1/2-power of H₂O₂ concentration. Dependence of the extraction rate on HN03 concentration was also examined.

Neptunium extracted into DIDPA from 0.5 M HN03 solution containing H₂O₂ was found to be in the tetravalent state in the organic phase, whereas neptunium in aqueous phase was in the pentavalent state. Reduction of Np(V) with H₂O₂ occurs rapidly in the presence of DIDPA. When the concentration of HNO3 was 4 M. the neptunium extracted was also tetravalent, but the reduction of NP(V) in an aqueous solution was also observed.     

Sphingomyelin Deacylase,the Enzyme Involved in the Pathogenesis of Atopic Dermatitis,Is Identical to the β-Subunit of Acid Ceramidase

A ceramide deficiency in the stratum corneum (SC) is an essential etiologic factor for the dry and barrier-disrupted skin of patients with atopic dermatitis (AD). Previously, we reported that sphingomyelin (SM) deacylase, which hydrolyzes SM and glucosylceramide at the acyl site to yield their lysoforms sphingosylphosphorylcholine (SPC) and glucosylsphingosine, respectively, instead of ceramide and/or acylceramide, is over-expressed in AD skin and results in a ceramide deficiency. Although the enzymatic properties of SM deacylase have been clarified, the enzyme itself remains unidentified. In this study, we purified and characterized SM deacylase from rat skin. The activities of SM deacylase and acid ceramidase (aCDase) were measured using SM and ceramide as substrates by tandem mass spectrometry by monitoring the production of SPC and sphingosine, respectively. Levels of SM deacylase activity from various rat organs were higher in the order of skin > lung > heart. By successive chromatography using Phenyl-5PW, Rotofor, SP-Sepharose, Superdex 200 and Shodex RP18-415, SM deacylase was purified to homogeneity with a single band of an apparent molecular mass of 43 kDa with an enrichment of > 14,000-fold. Analysis by MALDI-TOF MS/MS using a protein spot with SM deacylase activity separated by 2D-SDS-PAGE allowed its amino acid sequence to be determined and identified as the β-subunit of aCDase, which consists of α- and β-subunits linked by amino bonds and a single S-S bond. Western blotting of samples treated with 2-mercaptoethanol revealed that, whereas recombinant human aCDase was recognized by antibodies to the α-subunit at ~56 kDa and ~13 kDa and the β-subunit at ~43 kDa, the purified SM deacylase was detectable only by the antibody to the β-subunit at ~43 kDa. Breaking the S-S bond of recombinant human aCDase with dithiothreitol elicited the activity of SM deacylase with ~40 kDa upon gel chromatography. These results provide new insights into the essential role of SM deacylase expressed as an aCDase-degrading β-subunit that evokes the ceramide deficiency in AD skin.     

Small fatigue crack growth characteristics and fracture surface morphology of low carbon steel in hydrogen gas

Owing to energy conservation and environmental concerns, hydrogen has been suggested as a next-generation energy source. However, hydrogen known to seep into a metal, degrade its strength, and accelerate fatigue crack growth rates. We have investigated the effects of hydrogen gas on the small fatigue crack growth characteristics of low carbon steel JIS S10C by conducting bending fatigue tests on a specimen with a small blind hole and placed in a low-pressure hydrogen environment. The fatigue crack growth rate in hydrogen was higher than that in nitrogen. The fracture surface of the specimen in hydrogen showed intergranular facets in the low- growth-rate range and a quasi-cleavage fracture surface with brittle striations in the high-growth-rate range. The specimen only showed a ductile fracture surface for nitrogen. The small-fatigue-crack growth rate for nitrogen is given by ${dl/dN\propto \Delta \varepsilon_{p}^{n}l}$ , where l, N, and ${\Delta \varepsilon_{p}}$ represent the crack length, number of repetitions, and plastic strain range, respectively. This equation was also satisfied for hydrogen, but only over a short strain range from ${\Delta \varepsilon_t = 0.25}$ to 0.37?% in which the fracture surface exhibited intergranular facets and a ductile morphology, but no quasi-cleavage fracture. The exponent n of the equation was 1.22 in nitrogen and 0.66 in hydrogen environment. The small-fatigue-crack growth law can be used for safe material designs in hydrogen environments.     

Uranium and Plutonium Extraction from Nitric Acid by N,N-Di(2-Ethylhexyl)-2,2-Dimethylpropanamide (DEHDMPA) and N,N-Di(2-Ethylhexyl)Butanamide (DEHBA) using Mixer-Settler Extractors

Extraction properties of N,N-di(2-ethylhexyl)-2,2-dimethylpropanamide (DEHDMPA) for nitric acid, U(VI), and Pu(IV) were studied by a batch method using various nitric acid concentrations. The distribution ratio equations for nitric acid, U(VI), and Pu(IV) were derived. A continuous counter-current experiment was performed using mixer-settler extractors to determine the performance of a process that uses two types of monoamides, DEHDMPA and N,N-di(2-ethylhexyl)butanamide (DEHBA), as extractants. This process consisted of two cycles: one dedicated to extraction of U(VI) by DEHDMPA, and the other dedicated to the co-extraction of U(VI) and Pu(IV) by DEHBA. The feed solution used for the continuous counter-current experiment was 4 mol/dm³ nitric acid containing U(VI), Pu(IV), and simulated fission products. DEHDMPA exclusively extracted U(VI) from the feed at the 1st cycle, and the ratio of U recovered in the U fraction stream was 99.93%. The residual U and almost all Pu were extracted by DEHBA in the 2nd cycle, and the recovery of Pu in the U-Pu fraction stream was 99.94%. Concentration profiles of U and Pu in mixer-settlers were calculated using a simulation code, which confirmed that the calculation was effective for estimating the U concentration in the U fraction stream, and the U and Pu concentrations in the U-Pu fraction stream.