Search for novel amorphous alloys with high crystallization temperature by combinatorial arc plasma deposition

This paper describes a combinatorial search for novel amorphous alloys with high crystallization temperatures (T_x) using combinatorial arc plasma deposition (CAPD). The CAPD technique can deposit 1089 (33 × 33) thin film samples with different compositions on a substrate at one time. These 1089 samples on the substrate are individually referred to as CAPD samples and collectively referred to as a thin film library. Thin film libraries of Ir-Zr-Fe, Ir-Zr-Al, Mo-Zr-Al, Mo-Zr-Si, Ru-Zr-Fe and Ru-Zr-Si were deposited by CAPD. The compositions and phases of the CAPD samples were measured by energy dispersive X-ray fluorescence spectrometry and X-ray diffractometry, respectively. The results revealed that each library included amorphous CAPD samples. Since it is impossible to measure the T_x, fracture strength, fracture strain and Young's modulus of the CAPD samples by conventional measurement methods, larger samples having the same compositions as the amorphous CAPD samples were fabricated by a sputtering system. Since all CAPD samples of Ir-Zr-Fe and Ir-Zr-Al were too brittle, their corresponding sputter-deposited samples were not prepared. Sputter-deposited Mo-Zr-Al, Mo-Zr-Si, Ru-Zr-Fe and Ru-Zr-Si samples with ∼50 at.% Mo- or Ru-content were fabricated, and T_x and mechanical properties of these sputter-deposited samples were evaluated. All the sputter-deposited samples of Mo-Zr-Al and Mo-Zr-Si showed high T_x exceeding 973 K and as well as brittle characteristics. Ru₅₀Zr₃₅Fe₁₀ samples showed high T_x exceeding 1273 K and a low fracture strength of 0.26 GPa. Samples of Ru₅₁Zr₅Si₄₄ showed a high T_x of 923 K and a high fracture strength of 1.25 GPa.     

Fluorescence detection of single-nucleotide polymorphisms with two simple and low cost methods: a double-DNA-probe method and a bulge form method

Two 10-mer DNA probes, or one 20-mer DNA probe, respectively, hybridize with a 21-mer target DNA to form a vacancy or bulge opposite the target nucleotide. The former double-DNA-probe method and the latter bulge form method are applicable to the detection of single-nucleotide polymorphisms (SNPs). A small fluorescent dye enters into the vacancy or bulge and binds with a target nucleotide via a hydrogen bonding interaction, which causes fluorescence quenching. The interaction between fluorescent dye and the target nucleotide is confirmed by measuring the melting temperature and fluorescence spectra. The fluorescent dye, ADMND (2-amino-5,7-dimethyl-1,8-naphthyridine), is found to selectively bind with C over A or G. The methods proposed here are economic, convenient, and effective for the fluorescence detection of SNPs. Finally, the double-DNA-probe method and bulge form method are successfully applied to the detection of C/G and C/A mutations in the estrogen receptor 2 gene and progesterone receptor gene using ADMND.     

A homogeneous submanifold with nonzero parallel mean curvature vector in a Euclidean sphere

We show that every sufficiently high dimensional Euclidean sphere admits an odd dimensional Riemannian submanifold M having the properties: (1) M is a homogeneous submanifold with nonzero parallel mean curvature vector in the ambient sphere; (2) M is a Berger sphere; (3) M is a Sasakian space form of constant ${\phi}$ -sectional curvature. Note that our manifold M is diffeomorphic but not isometric to a Euclidean sphere.     

Morphology dependence of crystallization of natural rubber in blends

Crystallization of natural rubber (NR) was investigated in different morphology for NR/styrene butadiene rubber (SBR) blend and NR/polystyrene-(b)-polyisoprene (SI)/polystyrene (PS) blend. A purified NR (PC-TE) was prepared from pale crape via transesterification. In the blends, PC-TE formed various morphologies; that is, matrix phase, island phase and continuous phase with a nano-scale, respectively, in dependence upon the ratio of the rubbers. The crystallization rate of the blends was also significantly associated with the morphology of the rubbers.     

Synthesis and properties of (E)-1,2-difluoroethylene derivatives: improvement of the ultraviolet light stability

The synthesis and properties of (E)-α,β-difluorostilbene derivatives were studied. In particular, we investigated three suppression methods of (E)–(Z) isomerisation by shortening the molecular conjugation length, which included the introduction of a fluorine atom into the ortho or para position of the benzene ring or the replacement of the benzene ring with a cyclohexane ring. The relationship between the molecular structure of liquid crystals and the level of isomerisation by ultraviolet (UV) light was discussed.     

Degradation of EPDM seal used for water supplying system

Degradation of ethylene-propylene-diene (EPDM) rubber seal used for supplying water system was investigated through spectroscopic techniques. The EPDM seal was utilized at 20-45 °C for about 3 years. It was characterized by solid state nuclear magnetic resonance spectroscopy equipped with field gradient fast magic angle spinning probe and Fourier transform-infrared spectroscopy. Morphology of the EPDM seal was observed by scanning electron microscopy, focused ion beam scanning electron microscopy and electron probe micro-analysis. The hardness and crosslink density of EPDM seal were reduced by a factor of one-half after using for supplying water system, even though it contains little amount of carbon-carbon double bond. Surface of the EPDM seal was significantly damaged by water. The degradation of EPDM seal was associated with chain scission and oxidation of EPDM.