Crystallization of amorphous antimony films

Diffusion of the divalent impurities Mn²⁺, Ca²⁺, Cu²⁺, Fe²⁺, Co²⁺, Pb²⁺, Zn²⁺, Eu²⁺ and S^2- in sodium chloride and other alkali halide crystals has been studied by electron microscopy and diffraction. At temperatures in the range 100°–700°C the impurities diffuse to the surface and form oxides which in some cases are epitaxial. This distribution of the impurities on the surface is studied and is found to have a strong influence on the overgrowth of other epitaxial deposits.     

Influence of glass substrate thickness in laser scribing of glass

The thickness of the glass substrate used in liquid crystal displays continues to be decreased from its original thickness of 1.1 mm for the purpose reducing size and weight. The aim of this study was to clarify the influence of the glass substrate thickness during laser scribing with crack propagation caused by laser heating followed by quick quenching. The laser scribe conditions for soda-lime glass substrates with thickness equal to or less than 1.1 mm were obtained in laser irradiation experiments. Two-dimensional thermal elasticity analysis was conducted with a finite element method based on the scribable conditions obtained in the experiment. The laser scribable conditions can then be estimated by the upper limit of the maximum surface temperature, T_max, and the lower limit of the maximum tensile stress, σ_tmax, in the cooling area, regardless of the glass substrate thickness. There is a substrate thickness with which the maximum tensile stress σ_tmax becomes the largest under each scribe condition. The substrate thickness with which σ_tmax becomes the largest is obtained at a faster scribe velocity for thinner glass substrate and at slower scribe velocity for thicker glass substrate. Owing to these relations, the crack depth also has almost the same tendency as σ_tmax.     

Size Effects on the Mechanical Properties of Nanoporous Graphene Networks

It is essential to understand the size scaling effects on the mechanical properties of graphene networks to realize the potential mechanical applications of graphene assemblies. Here, a “highly dense‐yet‐nanoporous graphene monolith (HPGM)” is used as a model material of graphene networks to investigate the dependence of mechanical properties on the intrinsic interplanar interactions and the extrinsic specimen size effects. The interactions between graphene sheets could be enhanced by heat treatment and the plastic HPGM is transformed into a highly elastic network. A strong size effect is revealed by in situ compression of micro‐ and nanopillars inside electron microscopes. Both the modulus and strength are drastically increased as the specimen size reduces to ≈100 nm, because of the reduced weak links in a small volume. Molecular dynamics simulations reveal the deformation mechanism involving slip‐stick sliding, bending, buckling of graphene sheets, collapsing, and densification of graphene cells. In addition, a size‐dependent brittle‐to‐ductile transition of the HPGM nanopillars is discovered and understood by the competition between volumetric deformation energy and critical dilation energy.     

Hazard curve evaluation method development for a forest fire as an external hazard on nuclear power plants

A method to obtain a hazard curve of a forest fire was developed. The method has four steps: a logic tree formulation, a response surface evaluation, a Monte Carlo simulation, and an annual exceedance frequency calculation. The logic tree consists domains of “forest fire breakout and spread conditions”, “weather conditions”, “vegetation conditions”, and “forest fire simulation conditions.” Condition parameters of the logic boxes are static if stable during a forest fire or not sensitive to a forest fire intensity, and non-static parameters are variables whose frequency/probability is given based on existing databases or evaluations. Response surfaces of a reaction intensity and a fireline intensity were prepared by interpolating outputs from a number of forest fire propagation simulations by fire area simulator (FARSITE). The Monte Carlo simulation was performed where one sample represented a set of variable parameters of the logic boxes and a corresponding intensity was evaluated from the response surface. The hazard curve, i.e. an annual exceedance frequency of the intensity, was therefore calculated from the histogram of the Monte Carlo simulation outputs. The new method was applied to evaluate hazard curves of a reaction intensity and a fireline intensity for a typical location around a sodium-cooled fast reactor in Japan.     

Least detectable concentration and dynamic range of three immunoassay systems using the same antibody

The least detectable concentration (LDC) and dynamic range (DR) of three immunoassay systems are compared using four distinct antibodies (all specific for estradiol but with different affinities) on each system. The systems evaluated include the industry standard, ELISA, and two biosensors, surface plasmon resonance and kinetic exclusion. In all cases, the measurements of inhibition curves (response vs estradiol concentration) were contracted to outside experts (the biosensor manufacturers themselves in the case of the biosensors), each of whom was supplied with the same blind samples. Each biosensor manufacturer also reported an estimate of the equilibrium dissociation constant (Kd) for each of the antibodies. The LDC and DR observed for the kinetic exclusion biosensor are consistent with an interpretation of Kd limited detection while that from the other biosensor and ELISA show limits of detection somewhat above those expected for Kd limited performance. The determined LDC and DR of each biosensor is self-consistent in the sense that none of the inhibition data contradicts theoretical limits associated with the Kd as measured on that system; however, some contradictions are apparent across platforms. The use of multiple antibodies of differing Kd improves confidence that the observed differences in performance are associated with the immunoassay system rather than the particular analyte.     

Improving an immunoassay response to related polychlorinated biphenyl analytes by mixing antibodies

Immunoassays for detection of a class of closely related antigens, e.g., PCBs, have often been too specific (responding strongly to some members of the class and missing others) and no general method for adjusting the response has been described. In this paper, the difference in the response of a model immunoassay to different Kanechlors (Japanese commercial mixtures of PCBs, analogous to Aroclors in the United States) is reduced from 20- or 50-fold (depending on which antibody is used) to 3-fold when the antibodies are mixed at the proper ratio. A mathematical model based on competitive binding of two antibodies for up to four antigens has been developed and used to describe the assay performance and to predict optimum mix ratios for the antibodies used. The model (based on separate measurement of each antibody's effective Kd for each Kanechlor) provides an excellent fit to the measured mixed antibody assay response. The model is also successful in identifying cases where mixing monoclonal antibodies will not improve the response. It is thought the method described will have applicability in a variety of cases where the analytical goal is semiquantitative screening based on the total quantity of an unknown mixture of related compounds.     

Photo-induced properties of anodic oxide films on Ti6Al4V

Photocatalytic activity and wettability of the anodic oxide layer on Ti6Al4V prepared by anodization in a sulfuric acid electrolyte are explored. The oxide is composed mainly of TiO₂ with V₂O₅, VO₂ and Al₂O₃. The crystal structure of the TiO₂ varies from anatase to rutile with the sulfuric acid concentration in the electrolyte. Anatase exhibits better photocatalytic activity compared with rutile, which is different from those on Ti and Ti-Nb-Sn alloy. Contact angles of the oxides decrease with ultraviolet light illumination, and hydrophilicity is observed in the rutile oxide. Both photocatalytic activity and hydrophilicity are inferior to the corresponding Ti and Ti-Nb-Sn alloy, which is explained by the presence of Al₂O₃ in the anodic oxide.     

Preparation of Carbon-Doped TiO2 Nanopowder Synthesized by Droplet Injection of Solution Precursor in a DC-RF Hybrid Plasma Flow System

Carbon-doped titanium dioxide nanopowder has received much attention because of its higher photocatalytic performance, which is practically activated not only by UV, but also by visible light irradiation. In the present study, C-TiO₂ nanopowder was synthesized by droplet injection of solution precursor in a DC-RF hybrid plasma flow system, resulting in higher photocatalytic performance even under visible light irradiation. In-flight C-TiO₂ nanoparticles reacted with the high concentration of carbon in plasma flow and were then deposited on the surfaces of two quartz tubes in the upstream and downstream regions of this system. The collected C-TiO₂ nanopowder contained anatase-rutile mixed-phase TiO₂ and TiC, the contents of which depended on the location of the powder collection, the temperature, and the duration of plasma treatment. Highly functional C-TiO₂ nanopowder collected in the downstream region exhibited a higher degradation rate of methylene blue than that of single-phase anatase TiO₂, even under visible light irradiation, in spite of being TiC.     

Computational simulation of cold spray process assisted by electrostatic force

The integrated model of compressible thermofluid, splat formation and coating formation for the cold spray process has been established. In-flight behavior of nano-micro particles and the interaction between the shock wave and the particles in a supersonic jet flow impinging onto the substrate and further effect of electrostatic force on the particle acceleration are clarified in detail by carrying out a real-time computational simulation. The optimal particle diameters for an impinging particle velocity exceeding critical velocity exist. Particles with the diameter of submicron interact with shock wave and particles are decelerated prior to the impact. However, the particles can be accelerated considerably by utilizing electrostatic forces even in the presence of unavoidable shock waves. Finally, based on the integrated model, the coating thickness in an electrostatic assisted cold spray process is evaluated.