Fiber Optic Signal Attenuation by Secondary Ionizing Radiation in Nuclear Environments

Irradiation of optical fiber waveguides by ionizing radiation can cause an increased loss in optical transmission. The effect of the loss has been measured on several commercially available pure silica core boron-doped clad fibers irradiated with thermal neutrons from a nuclear reactor. In the present work, optical absorptions were measured over the 400-1100nm range during the neutron irradiation. We have found that the attenuation of optical transmission by thermal neutrons is caused by defects produced by alpha particles which are produced in boron-neutron reactions.     

Effect of suspension potential on the oxidation rate of copper concentrate in a sulfuric acid solution

A chalcopyrite concentrate containing 17 pct pyrite was oxidized in 1 mol/dm³ sulfuric acid solution at 90 °C (363.2 K). The suspension potential (Ptvs SCE, in the presence of Fe³⁺/Fe²⁺) was maintained constant in the range 0.30 to 0.65 V by controlled additions of KMnO₄ solution. The oxidation appeared to be under surface reaction control. The rate constant was nearly independent of total Fe concentration (0.01 to 0.5 mol/dm³), but increased rapidly with a rise in suspension potential until it reached a maximum at 0.40 to 0.43 V, after which there was marked decrease at around 0.45 V. Chalcopyrite in the concentrate was oxidized to form elemental sulfur over the whole of the suspension potential range, whereas the oxidation of pyrite took place only above 0.45 V and yielded sulfate ion. At 0.40 V the apparent activation energy was 47 kJ/mol. An analogy between the potential dependence of the rate and the Tafel correlation for an electrode process is discussed.     

Formation and Transformation of Solid Solutions in the System Nb2O5–Ta2O5

In the system Nb₂O₅–Ta₂O₅, a continuous series of δ-Nb₂O₅ (δ-Ta₂O₅) solid solutions with a hexagonal cell is formed while heating amorphous materials prepared by the simultaneous hydrolysis of niobium and tantalum alkoxides. The lattice parameters a and c change linearly with increasing Ta₂O₅ content; the former value increases from 0.3604 to 0.3620 nm, and the latter value decreases from 0.3923 to 0.3883 nm. They transform to γ-Nb₂O₅ (β-Ta₂O₅) solid solutions with an orthorhombic cell at higher temperatures. The changes in lattice parameters a and c as functions of composition are the same as those of hexagonal solid solutions, whereas parameter b is relatively constant.     

Identification of two closely related genes, inducible and noninducible carbonyl reductases in the rat ovary

OBJECTIVE: To investigate the potential role of cytokines in psoriatic arthritis (PsA) by assessing the profiles of the proinflammatory cytokines in synovial fluid (SF) of PsA in comparison with rheumatoid arthritis (RA) and osteoarthritis (OA). METHODS: Levels of tumor necrosis factor-alpha (TNF-alpha), interleukin 1 (IL-1), IL-6, and IL-8 were measured in SF using ELISA. RESULTS: Levels of TNF-alpha, IL-1beta, and IL-8 were significantly higher in PsA SF than in OA SF, although lower than in RA SF. No difference was detected in the IL-6 levels between PsA and RA SF, both of which were much higher than in OA SF. CONCLUSION: The pattern of expression of proinflammatory cytokines seen in PsA is similar to that in RA. Since PsA is also a destructive arthropathy, cytokines, in particular TNF-alpha and IL-1, may be principle factors in joint destruction.     

Synthesis of well-defined graft copolymer with oligodimethylsiloxane and polyvinylalcohol branches

Summary Polyvinylalcohol macromer of well controlled molecular weight and molecular weight distribution, whose hydroxyl groups being protected as silyl ethers, was synthesized by Lewis acid catalyzed sequential silyl aldol condensation. Copolymerization of p-oligodimethylsiloxanylstyrene with the macromer, followed by the removal of the hydroxyl protective groups, gave the well-defined title graft copolymer.     

Mechanical strength of calcium phosphate cement in vivo and in vitro

Two different kinds of calcium phosphate cement were developed for implant fixation: cement A comprised of alpha-tricalcium phosphate (alpha-TCP) 95% and dicalcium phosphate dihydrate (DCPD) 5%, and cement B comprised of alpha-tricalcium phosphate 90% and dicalcium phosphate dihydrate 10%. The compression strength and pullout force of the new materials were tested both in vitro and in vivo. Microscopic observations were performed on the interface between bone and cement. Cement A showed a greater mechanical strength than cement B. The results suggest the clinical possibility of this calcium phosphate cement, which could be used as a material for enhancing implant fixation.     

Electron microscopic immunolocalization of caltrin proteins in guinea pig seminal vesicles

We report here on five new cases of solid and cystic papillary neoplasm (SCPN) of the pancreas diagnosed by fine-needle aspiration cytology (FNAC). All cytologic samples were obtained by ultrasonography, and the smears were conventionally fixed and stained. Special histochemical and immunocytochemical stains were also performed in some samples. Cytology revealed in all but one case numerous pseudopapillary structures composed of fibrovascular stalks lined with one or more layers of bland-appearing, uniform tumor cells. The tumor cells had round-to-oval euchromatic nuclei with frequently folded smooth contours and one or two small nucleoli. Their cytoplasm often contained eosinophilic, PAS-positive, and diastase-resistant inclusions. Foamy cells, psammoma bodies, blood, and cellular debris were found in the background. The criteria for the differential diagnosis versus other pancreatic lesions are discussed in some detail, as is the role of immunocytochemistry (ICC). In the literature, only 28 cases of cytologically investigated SCPN have been reported to the best of our knowledge. The most helpful criteria for the conclusive identification of SCPN by FNAC include the pseudopapillary arrangement with bland-appearing tumor cells, and, especially, the finding of acidophilic, PAS-positive, and diastase-resistant cytoplasmic granules.     

Measurement of contact resistance distribution using a 4k-contactsarray

A new test structure suitable for measuring a contact resistance distribution has been developed. It includes the following two components: a 256 row, 16 column (= 4096) four-terminal cross-contact array; and peripheral circuits, which consist of an eight-stage CMOS binary counter and 256-bit CMOS decoders. It was found that contact resistance can be fitted by a Gaussian distribution for more than three standard deviations of the mean value. The relationship between the contact size and the standard deviation of the contact resistance has been discussed for two types of contacts: Al/TiN/TiSi₂-n⁺Si, and WSi₂/poly-n⁺Si. This test structure can simultaneously measure the series resistance of a two-terminal contact chain and the individual contact resistance. By comparing the results of the two measurement modes, it was found that there are three kinds of contact resistance distribution in the chips which have high series resistance of the two-terminal contact chain