A serious disease of amphibians caused by the chytrid fungus Batrachochytrium dendrobatidis was first found in Japan in December 2006 in imported pet frogs. This was the first report of chytridiomycosis in Asia. To assess the risk of pandemic chytridiomycosis to Japanese frogs, we surveyed the distribution of the fungus among captive and wild frog populations. We established a nested PCR assay that uses two pairs of PCR primers to amplify the internal transcribed spacer (ITS) region of a ribosomal RNA cassette to detect mild fungal infections from as little as 0.001 pg (1 fg) of B. dendrobatidis DNA. We collected swab samples from 265 amphibians sold at pet shops, 294 bred at institutes and 2103 collected at field sites from northern to southwestern Japan. We detected infections in native and exotic species, both in captivity and in the field. Sequencing of PCR products revealed 26 haplotypes of the B. dendrobatidis ITS region. Phylogenetic analysis showed that three of these haplotypes were specific to the Japanese giant salamander (Andrias japonicus) and appeared to have established a commensal relationship with this native amphibian. Many other haplotypes were carried by alien amphibians. The highest genetic diversity of B. dendrobatidis was found in the American bullfrog (Rana catesbeiana). Some strains of B. dendrobatidis appeared to be endemic to Japanese native amphibians, but many alien strains are being introduced into Japan via imported amphibians. To improve chytridiomycosis risk management, we must consider the risk of B. dendrobatidis changing hosts as a result of anthropogenic disturbance of the host-specific distribution of the fungus.

The Young's moduli of various oxide glasses (silicate, borate, phosphate, and tellurite) were measured using an ultrasonic method. To predict the Young's moduli of the oxide glass systems, empirical compositional parameters Gi and Vi, based on the Makishima‐Mackenzie theory, were obtained, where Gi is the dissociation energy and Vi the packing density parameter of a single‐component oxide. The relationship between the calculated Young's modulus from the compositional parameters and the measured Young's modulus was investigated. Experimental results indicated that the Young's modulus of phosphate and tellurite glasses could not be predicted using these parameters. Thus, it was necessary to modify the Gi, by considering P2O5 and TeO2 as glass network formers. As for the phosphate glass, it exhibited a layered structure that consisted of P=O double bond and three chains of P‐O bond. In this paper, the modified Gi of P2O5 was calculated using the assumption that the P=O double bond is a nonbridging bond and does not contribute to Young's modulus. In the case of tellurite glass, the glass structure is mainly composed of TeO4 trigonal pyramids, and the addition of other oxides results in structural changes to the TeO3 trigonal pyramid. However, the mechanisms of such structural changes have not yet been clarified. Therefore, the modified Gi of TeO2 was calculated from the measured value using the density and Young's modulus of pure TeO2 glass. The results revealed that the calculated values using our proposed parameter were in good agreement with measured values all through the oxide glasses.

Silicate glasses have evolved from basic structural materials to enabling materials for advanced applications. In this article, we unravel the origin of the mixed alkali effect for alkali silicate 22.7R 2 O-77.3SiO 2 glasses (R = Na and/or K) by identifying the variation in the alkali ion location around the non-bridging oxygen atoms. To do so, we constructed a state-of-the art structural model, which reproduces both diffraction and NMR data with a particular focus on the behavior of the alkali ions. A novel topological analysis using persistent homology found that sodium-potassium silicate glass shows a significant reduction in large cavities as a result of the mixed alkali effect. Furthermore, a highly correlated pair arrangement between sodium and potassium ions around non-bridging oxygen atoms was identified. The potassium ions can be trapped in K-O polyhedra due to the increased bridging oxygen coordination; therefore, the correlated pair arrangement is likely the intrinsic origin of the mixed alkali effect.

The density of oxide glass including silicate, borate, phosphate, tellurite, and germanate glasses were measured using the Archimedes method. On the assumption that the ionic packing ratio is approximately a constant independent of chemical composition, an empirical equation for estimating the density from chemical composition was proposed. The calculated values are in reasonable agreement with the corresponding measured ones. I. IntroductionT HE density of glass is undoubtedly one of the most important properties in industrial glass production, and is required for calculating other properties, such as refractive index, elastic properties, and thermal conductivity. Academically, density, which is related to the molar volume and the ionic packing ratio, plays a significant role in the study of structure in materials, whether they are inorganic, polymeric, or metallic in nature.In the case of glass, the density depends almost entirely on chemical composition. Therefore, the problem of calculating the density according to their chemical composition has been the focus of much expert attention. 1-6 For example, Priven and Mazurin 1 compared various methods for the density estimation, reporting estimation errors of 0.038-0.11 g/cm 3 for glasses containing 450 mol% silica. Some important models were also summarized by Scholze (p. 204). 2 In 2007, Fluegel 3 performed a statistical analysis of the available silicate glass density data in SciGlass 7 and succeeded in reducing the density estimation errors provided by Priven and Mazurin. 1 Linard et al. 6 proposed a model to predict the density of complex molten borosilicate glass in the temperature range from 9001 to 13001C. Although these models make it possible to carry out calculations with a fairly high degree of accuracy, they are often valid only for glasses containing mainly silica.The purpose of this work is to propose a guideline in predicting the density from chemical composition. We systematically measured the density of silicate, borate, phosphate, tellurite, and germanate oxide glasses. The empirical equation for calculating the density from chemical composition is derived by use of this experimental result and the data from INTER-GLAD database. 8

Entropic elasticity, a property typical of rubbers and well known in organic polymers with appropriate network structures, is not known to occur in oxide glasses. Here, we report the occurrence of entropic elasticity in phosphate-glass fibres with highly anisotropic structures, drawn by mechanical elongation from supercooled liquids. We observed a large lengthwise shrinkage of ~35% for phosphate glasses with an enhanced one-dimensional structure, as well as a distinct endotherm on reheating them up to temperatures between that of the glass transition temperature and the softening temperature. Our results strongly suggest the possibility of designing oxide glasses with a rubbery nature at high temperatures.