High-resolution GaP Terahertz Spectrometer and Its Application to Detect Defects in Gamma-irradiated Glucose Crystal

We developed high-resolution GaP THz signal generator using Cr:Forsterite lasers with gratings as both a pump and a signal beam for difference-frequency generation. A line width of less than 500 MHz and a wide tunable frequency range (0.6–6.2 THz) provide sufficient resolution for measuring materials with sharp absorption bands using the generator as the light source for a THz spectrometer. This is suitable for materials such as gases or solid samples at low temperatures. We demonstrated the detection of defects in organic materials, as they appear as slight deviations in the absorption frequency in the THz region.     

Aging behavior of the Ti-29Nb-13Ta-4.6Zr new beta alloy for medical implants

The aging behavior of the Ti-29Nb-13Ta-4.6Zr alloy quenched from 1033 K was investigated by employing electrical resistivity (ρ) and Vickers hardness (HV) measurements, optical microscopy (OM), and X-ray diffraction (XRD). Upon aging at 573 K, the ρ value at room- and liquid-nitrogen temperatures initially increased to 120 and 30 ks, respectively, and decreased with continued aging time. The HV value started to increase from 0.06 ks and the isothermal ω phase was identified at 300 ks of aging by XRD. On aging at 773 K, an incubation period of 6 ks was observed for the ρ change at both temperatures, following which ρ decreased. An incubation period for the HV change was extended up to 12 ks, and then HV increased. Precipitated α was observed and identified by OM and XRD, respectively, whereas no reflections of isothermal ω phase were identified during the whole aging time at 773 K. The upper-limit temperature of isothermal ω precipitation is situated at around 673 K.     

Self-Lubrication of Chlorine-Implanted Titanium Nitride Coating

Chlorine implantation into TiN coatings decreases the wear loss and the friction coefficient. Even by low-dose chlorine implantation, the wear volume is decreased by three orders of magnitude or more, and the friction coefficient becomes <0.1. This self-lubrication mechanism is related to the presence and mobility of implanted chlorine atoms inside the columnar TiN microstructure. According to observations of chlorine-implanted TiN coatings using high-resolution transmission electron microscopy, the chlorine atoms are present in the damaged region, where TiN is composed of nanosized grains. From these data, a self-lubrication mechanism is proposed with chlorine catalyzing the oxidation of titanium and leading to the formation of some tribological reaction product.     

Solving exclusionary side constrained transportation problem by using a hybrid spanning tree-based genetic algorithm

In real life applications we often have the following problem: How to find the reasonable assignment strategy to satisfy the source and destination requirement without shipping goods from any pairs of prohibited sources simultaneously to the same destination so that the total cost can be minimized. This kind of problem is known as the transportation problem with exclusionary side constraint (escTP). Since this problem is one of nonlinear programming models, it is impossible to solve this problem using a traditional linear programming software package (i.e., LINDO). In this paper, an evolutionary algorithm based on a genetic algorithm approach is proposed to solve it. We adopt a Prüfer number to represent the candidate solution to the problem and design the feasibility of the chromosome. Moreover, to handle the infeasible chromosome, here we also propose the repairing procedure. In order to improve the performance of the genetic algorithm, the fuzzy logic controller (FLC) is used to dynamically control the genetic operators. Comparisons with other conventional methods and the spanning tree-based genetic algorithm (st-GA) are presented and the results show the proposed approach to be better as a whole.     

Analysis of catalytic action of transglutaminase induced in human promyelocytic leukemia (HL-60) and human hepatoblastoma (HepG2) cells

Transglutaminase is a calcium-dependent enzyme that catalyzes an amine incorporation and a cross-linking of proteins. Intracellular transglutaminase is induced when human promyelocytic leukemia HL-60 cells are treated with retinoic acid and human hepatoblastoma HepG2 cells, with interleukin-6. To find whether the intracellular reaction catalyzed by transglutaminase increased when the enzyme is induced in these cells, the transglutaminase-catalyzed incorporation of 14C-labeled methylamine into cellular proteins was measured. The incorporation level of the labeled methylamine into proteins of HL-60 and HepG2 cells did not increase after the transglutaminase had been induced. The presence of the calcium ionophore A23187 did not affect these results. These findings suggested that even after the enzyme induction the catalytic action of intracellular transglutaminase is maintained at a constant level in these cells by unknown regulatory mechanism(s).     

Effect of polymer matrix on the performance of pressure‐sensitive paint comprising 5,10,15,20‐tetrakis(pentafluorophenyl)porphinato platinum(II) and poly(1,1,1,3,3,3‐hexafluoroisopropyl‐co‐tert‐butyl methacrylates)

Copolymers of 1,1,1,3,3,3‐hexafluoroisopropyl methacrylate (HFIPM) and tert‐butyl methacrylate (TBM) were prepared by conventional radical copolymerization as a novel binders for pressure‐sensitive paints (PSP). The monomer reactivity ratios r_HFIPM and r_TBM were determined as 0.45 and 0.67, respectively. The glass transition temperature of the copolymers increased from 77 to 126°C with increasing mole fraction of TBM units in the copolymer. The PSP were formed by combining the resulting copolymers and 5,10,15,20‐tetrakis(pentafluorophenyl)porphinato platinum(II). The pressure and temperature sensitivities of the PSPs were measured at air pressures ranging from 5 to 120 kPa and at temperatures ranging from 0 to 60°C. Modified Stern–Volmer plots indicated slight increases in the pressure sensitivity, but significant decrease in the temperature sensitivity as the mole fraction of HFIPM units increased in the copolymer. Applying a theoretical model to our calibration data, we inferred that luminescence quenching is primarily responsible for increasing the temperature sensitivity in the resulting copolymers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43316.     

Application of chitosan solutions gelled by melB tyrosinase to water‐resistant adhesives

An investigation was undertaken on the application of dilute chitosan solutions gelled by melB tyrosinase‐catalyzed reaction with 3,4‐dihydroxyphenethylamine (dopamine). The tyrosinase‐catalyzed reaction with dopamine conferred water‐resistant adhesive properties to the semi‐dilute chitosan solutions. The viscosity of the chitosan solutions highly increased by the tyrosinase‐catalyzed quinone conversion and the subsequent nonenzymatic reactions of o‐quinones with amino groups of the chitosan chains. The viscosity of chitosan solutions highly increased in shorter reaction times by addition of melB tyrosinase. Therefore, in this study, the gelation of a chitosan solution was carried out without poly(ethylene glycol) (PEG), which was added for the gelation of chitosan solutions using mushroom tyrosinase. The highly viscous, gel‐like modified chitosan materials were allowed to spread onto the surfaces of the glass slides, which were tightly lapped together and were held under water. Tensile shear adhesive strength of over 400 kPa was observed for the modified chitosan samples. An increase in either amino group concentration of the chitosan solutions or molecular mass of the chitosan samples used effectively led to an increase in adhesive strength of the glass slides. Adhesive strength obtained by chitosan materials gelled enzymatically was higher than that obtained by a chitosan gel prepared with glutaraldehyde as a chemical crosslinking agent. In addition, the use of melB tyrosinase led to a sharp increase in adhesive strength in shorter reaction times without other additives such as PEG. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Surface hardening of biomedical Ti–29Nb–13Ta–4.6Zr and Ti–6Al–4V ELI by gas nitriding

The microstructure and hardness near the surface of a biomedical titanium alloy, Ti–29Nb–13Ta–4.6Zr (TNTZ), subjected to gas nitriding at 1023–1223 K was investigated in comparison with the conventional biomedical Ti–6Al–4V ELI (Ti64). After gas nitriding, the microstructure near the specimen surface was observed by optical microscopy, X-ray diffraction (XRD), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS). In both alloys, two types of titanium nitrides (TiN and Ti₂N) are formed and the phase is precipitated by gas nitriding. Furthermore, the oxygen impurity in the gas nitriding atmosphere reacts with the titanium nitrides; thus, TiO₂ is formed at the outermost titanium nitride layer. The surface hardening was also evaluated by Vickers hardness measurement. The Vickers hardness near the surface of TNTZ and Ti64 increases significantly by gas nitriding.     

Achromatic interfero-coronagraph with two common-path interferometers in tandem

To attain deeper nulling for an extended incoherent star disk a scheme for an achromatic interfero-coronagraph, incorporating two common-path interferometers in tandem, is proposed. Analytical and numerical predictions of the performance, which are in reasonably good agreement, are presented. The predicted performance improvement, by using two interferometers in tandem, is demonstrated by a preliminary experiment. A star coronagraph based on the proposed technique has the possibility to reach a 10(-10) achromatic nulling contrast for an almost 10(-2) lambda/D effective source size.