Cloning an Autonomous Replication Sequence from Aspergillus oryzae

DNA sequence from Aspergillus oryzae genome which, confers on pOK-1 the ability to replicate autonomously in Saccharomyces cerevisiae is described. A hybrid plasmid pOK-1 was constructed from pBR325 and YEp13 fragment containing Leu2⁺ gene. Asp. oryzae DNA and pOK-1 were cleaved with BamHI, ligated and introduced into Escherichia coli. About 600 recombinant plasmids were obtained. One of them transforms S. cerevisiae SHY3 to Leu2⁺ with middle efficiency. The plasmid designated as pSB1–2 contained two BamHI fragments (4.3 kb and 4.1 kb) of Asp. oryzae DNA.     

Compositional Dependence of Normal Spectral Emissivity of Molten Cu-Fe Alloy

Metallurgical and Materials Transactions B - Normal spectral emissivity of molten Cu-Fe alloy with different compositions was measured at the wavelength of 807 nm using an electromagnetic...     

Deoxidation of Ti Melt by Newly Developed Two-Step Plasma Arc Melting Process Using Hydrogen

Metallurgical and Materials Transactions B - A two-step plasma arc melting process, comprising a first step under Ar-30 pct H2 gas flow and the second step under Ar gas flow, has been...     

Single-particle-diagnosis approach: An efficient strategy for discovering new nitride phosphors

Discovery of novel phosphors is extremely important to target the ever change of the solid state lighting technology. In this paper, we present a high-speed way to discover new phosphors, namely single-particle-diagnosis approach. This approach is based on investigating the crystal structure and luminescence of a tiny single crystal, without the necessity of the growth of large-size single crystals or the preparation of single phase powder samples. The concept of the approach and some new nitride phosphors explored by this approach are shown in this paper.     

Analyses of reactor building by 3D nonlinear FEM models considering basemat uplift for simultaneous horizontal and vertical ground motions

The nonlinear behavior of basemat uplift, which is an important point in seismic designs of nuclear power plants in Japan, has been investigated by arranging joint elements between the reactor building basemat and the soil on a three-dimensional (hereafter referred to as 3D) FEM model of the soil. However, the nonlinearity of the basemat uplift has been investigated separately from the nonlinearity of reactor buildings. These nonlinearities have yet to be taken into account simultaneously in past studies. In this paper, models of the building and the soil using 3D FEM elements with consideration to the nonlinearity of building materials as well as the nonlinearity of the basemat uplift were subjected. The behavior of the building's elements were investigated by carrying out seismic response analyses for horizontal ground motions only, as well as for simultaneous horizontal and vertical ground motions using these models. As a result, it was found that there was little difference in the horizontal response of the building between the horizontal input motions only and the simultaneous horizontal and vertical input motions. The effects of the vertical ground motions on the basemat uplift behavior which is represented by the ground contact ratio were also slight.     

Crystal, electronic and luminescence properties of Eu-doped Sr2Al2−xSi1+xO7−xNx

The crystal and electronic structures, as well as the luminescence properties of Sr₂Al_2−xSi_1+xO_7−xN_x:Eu²⁺ are reported. First-principles calculations energetically confirm that the Al and Si atoms are in partial ordering in the 2a and 4e sites in Sr₂Al₂SiO₇. In addition, the band structure calculation shows that Sr₂Al₂SiO₇ has an indirect band gap with an energy gap of about 4.07 eV, which is in good agreement with the experimental data (5.3 eV) obtained from the diffuse reflection spectrum. The crystal structure of Sr₂Al₂SiO₇ can be modified by Si–N substitution for Al–O in the lattice with a maximum solubility of about x=0.6. The average bond length of Eu_Sr^-(O,N) slightly increases although the lattice parameters decrease with the incorporation of Si–N in Sr₂Al₂SiO₇:Eu²⁺. Under excitation in the visible spectral region, Sr₂Al_2−xSi_1+xO_7−xN_x:Eu²⁺ emits blue to yellow light with a broad emission band in the range of 480–570 nm, varying with both the Eu concentration and the x value. The red shift of the emission band of Eu²⁺ is associated with an increase in the crystal-field splitting and the covalency, which arise from the incorporation of nitrogen as well as the energy transfer between the Eu ions at high Eu concentrations. Moreover, the Eu ions have a strong effect on both the concentration quenching and the thermal quenching in Sr₂Al_2−xSi_1+xO_7−xN_x. The temperature dependence of photoluminescence indicates that Sr₂Al_2−xSi_1+xO_7−xN_x:Eu²⁺ shows strong thermal quenching due to the dominant nonradiative process at room temperature.     

Fabrication of silicon nitride nanoceramics—Powder preparation and sintering: A review

Fine-grained silicon nitride ceramics were investigated mainly for their high-strain-rate plasticity. The preparation and densification of fine silicon nitride powder were reviewed. Commercial sub-micrometer powder was used as raw powder in the “as-received” state and then used after being ground and undergoing classification operation. Chemical vapor deposition and plasma processes were used for fabricating nanopowder because a further reduction in grain size caused by grinding had limitations. More recently, nanopowder has also been obtained by high-energy milling. This process in principle is the same as conventional planetary milling. For densification, primarily hot pressing was performed, although a similar process known as spark plasma sintering (SPS) has also recently been used. One of the advantages of SPS is its high heating rate. The high heating rate is advantageous because it reduces sintering time, achieving densification without grain growth. We prepared silicon nitride nanopowder by high-energy milling and then obtained nanoceramics by densifying the nanopowder by SPS.     

Carbon Nitride Loaded with an Ultrafine,Monodisperse, Metallic Platinum-Cluster Cocatalyst for the Photocatalytic Hydrogen-Evolution Reaction

For the realization of a next-generation energy society, further improvement in the activity of water-splitting photocatalysts is essential. Platinum (Pt) is predicted to be the most effective cocatalyst for hydrogen evolution from water. However, when the number of active sites is increased by decreasing the particle size, the Pt cocatalyst is easily oxidized and thereby loses its activity. In this study, a method to load ultrafine, monodisperse, metallic Pt nanoclusters (NCs) on graphitic carbon nitride is developed, which is a promising visible-light-driven photocatalyst. In this photocatalyst, a part of the surface of the Pt NCs is protected by sulfur atoms, preventing oxidation. Consequently, the hydrogen-evolution activity per loading weight of Pt cocatalyst is significantly improved, 53 times, compared with that of a Pt-cocatalyst loaded photocatalyst by the conventional method. The developed method is also effective to enhance the overall water-splitting activity of other advanced photocatalysts such as SrTiO₃ and BaLa₄Ti₄O₁₅.     

Ubiquitin in cerebrospinal fluid: a rapid competitive enzyme-linked immunoflow assay

The aims of this study were to develop a rapid immunoassay to determine the levels of ubiquitin in cerebrospinal fluid and to establish the ubiquitin levels in the spinal fluid of normal aged individuals. A competitive enzyme-linked immunoflow assay was developed. In this assay, ubiquitin is bound to nitrocellulose membrane, after which the primary antibody-test sample mixture and the enzyme-labeled secondary antibody under vacuum are applied sequentially. The final reaction product is collected in a microtiter plate by suction. This competitive assay requires only approximately 4 h and is potentially useful for determining in biological fluids the levels of any antigen or its antibodies that might be present. Employing this immunoassay, cerebrospinal fluid ubiquitin levels were found to be 147.5 +/- 5.2 ng ml-1 in non-neurological aged cases.