The effects of different inorganic salts,buffer systems,and desalting of Varthemia crude water extract on DPPH radical scavenging activity

The DPPH radical-scavenging activity of 25 inorganic salts, two buffer systems, and crude water extract of aerial parts of Varthemia (Varthemia iphionoides) before and after resins purification were investigated. Eight of the 25 inorganic salts tested quenched the DPPH radical colour. Na₂S₂O₃ and FeCl₂ showed markedly high DPPH colour-quenching activity, with inhibition of 65.3% and 47.7% respectively, at a concentration of 10 μg/ml. Four salts slightly increased the intensity of DPPH radical colour. The rest of tested salts, acetate buffer, and phosphate buffer at a concentration less than 0.1 mM did not affect DPPH radical colour. The DPPH radical-scavenging activity of BHT and catechol was considerably affected by the concentration of phosphate buffer (pH 7.0), and by acetate buffer (pH 5.0) at concentrations more than 0.01 mM in the case of BHT only. The DPPH radical-scavenging activity of a crude water extract of aerial parts of Varthemia iphionoides was much higher than that of an extract desalted by cation-exchange resin, indicating that iron ions apparently elevated the DPPH radical-scavenging activity of the extract. Therefore, desalting of plant extracts is important in order to obtain the true value of DPPH radical-scavenging activity.     

Investigation of Four-Wavelength Regenerator Using Polarization- and Direction-Multiplexing

We demonstrate a four-channel extension to the Mamyshev regenerator and investigate its potential for the simultaneous processing of 4$,times,$10 Gb/s return-to-zero wavelength division-multiplexed channels. Mitigation of the interchannel nonlinearities is achieved through the rapid walkoff induced by both the large differential group delay of a specially developed polarization maintaining highly nonlinear fiber and a bidirectional architecture. Numerical and experimental results demonstrate the reduction of interchannel crosstalk as well as the potential of the scheme for 2R regeneration.      

Optical trapping of nanoparticles on a silicon subwavelength grating and their detection by an ellipsometric technique

A method and setup are proposed for trapping and detecting nanoparticles dispersed in a nanocomposite solution using periodically localized light generated by a subwavelength transmission grating. By numerical simulations, it is shown that there is an optimum duty ratio of the grating to produce the periodically localized light. Experimental results are presented for Au/γ-Fe₂O₃ composite nanoparticles having a diameter of 21.0 nm trapped on a silicon subwavelength rectangular grating and detected ellipsometrically. The technique should prove useful for evaluating optical and mechanical properties of nanocomposite materials.     

Liquid film flow rising along the outer surface of the rotating cone

We have investigated fluid flow characteristics of liquid film flow rising along the outer surface of a rotating cone. The fluid is given a centrifugal force due to the rotation of the cone, while strong surface tension maintains the centrifugal force at the outer surface of the liquid film flow. Therefore, the fluid does not spread outward from the cone, but goes up along it. We have visualized the interesting flow phenomena with a high‐speed video camera. In addition, we have measured the correlation between the wetted radius, rotation rate of the cone, and flow rate of the rising film flow. © 2010 Wiley Periodicals, Inc. Heat Trans Asian Res; 39(7): 492–496, 2010; Published online 2 June 2010 in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/htj.20307     

Mechanical properties and microstructures of β Ti–25Nb–11Sn ternary alloy for biomedical applications

The mechanical properties and microstructures of β Ti–25%Nb–11%Sn ternary alloy rods were investigated for biomedical applications as a function of heat treatment temperature after swaging by an 86% reduction in cross-section area. An as-swaged rod consisting of a β (bcc) single phase shows a low Young's modulus of 53 GPa, which is interpreted in terms of both the metastable composition of the β alloy undergoing neither an athermal ω transformation nor a deformation-induced ω transformation and < 110>texture development during swaging. Heat treatment at 673 K (400 °C) for 2 h leads to a high strength of approximately 1330 MPa and a high spring-back ratio of yield stress to Young's modulus over 15 × 10^? 3, with acceptable elongation. This high strength is attributable to needle-like α precipitates, which are identified by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and high-resolution electron microscopy (HREM).     

29Si MASNMR Spin-Lattice Relaxation Study of α-, β-, and Amorphous Silicon Nitride

The spin-lattice relaxation times, T ₁, in α-, β-, and amorphous Si₃N₄ have been obtained for the first time, using a multiple-pulse saturation recovery method. The saturation recovery of the ²⁹Si magnetization follows exponential behavior under magic-angle spinning conditions, within the limits of experimental error. A rather wide dispersion of T ₁ values is observed for the phases of Si₃N₄: 284 ± 29 min (–46.686 ppm) and 260 ± 23 min (–48.812 ppm) for the α-phase, 36 ± 4 min for the β-phase, and 11 ± 1 min for the amorphous phase, assuming an exponential recovery. The values obtained for the exponent in the power-law fitting are 0.599(9) (–46.686 ppm) and 0.61(1) (–48.812 ppm) for the α-phase, 0.52(2) for the β-phase, and 0.53(3) for the amorphous phase.     

Precipitation and Calcination Processes for Yttrium Aluminum Garnet Precursors Synthesized by the Urea Method

Yttrium aluminum garnet (YAG) precursors for transparent ceramics were synthesized by the urea method under various [urea]/[metal ions] ([U]/[M]) conditions. Monophase YAG was obtained from solutions with a high [U]/[M] ratio after calcination at a temperature of 1200°C. The condition of the precipitates seemed to indicate that the yttrium compounds had precipitated onto the aluminum compounds. The surface morphology and size of the particles were controlled by the [U]/[M] ratio. The different reaction sequences of YAG crystallization for low- and high-ratio samples were dependent on morphology, size, and the quantity of chemical species that was precipitated as carbonate and/or sulfate compounds.     

Study on the Effect of Elastic Stress and Microstructure of Low Carbon Steels on Barkhausen Noise

The present study investigates the effect of elastic stress and microstructure on Barkhausen noise in low carbon steels subjected to different heat treatments. Barkhausen noise in an as-received test piece and a test piece heated at 450 ^°C for 1.5 hours was found to increase with increasing elastic stress. However, in a test piece heated at 700 ^°C for 10 hours, Barkhausen noise was observed to saturate with increasing elastic stress following an initial increase. To clarify the reason for this saturation behavior, magnetization measurements were carried out and the microstructure and texture of the test pieces were evaluated using microscopy and electron backscatter diffraction. The results indicated that for the test piece heated at 700 ^°C for 10 hours, a drastic change in the microstructure occurred compared to that for the other test pieces. From the experimental and analytical results, it was concluded that for the former test piece, Barkhausen noise saturated under a low elastic stress due to the globularization of pearlite, which caused 90^° domain walls to become 180^° domain walls when a low elastic stress is applied.     

Low-temperature water-splitting by sodium redox reaction

Thermochemical water-splitting by sodium redox reactions was investigated from material science point of view as a future hydrogen production method. The reaction system consists of three separate reactions, which are hydrogen generation by NaOH-Na reaction, metal separation by thermolysis of Na₂O, and oxygen generation by hydrolysis of Na₂O₂. Although the current techniques of thermochemical water-splitting required a temperature higher than 800 °C for whole reaction cycle, the sodium system was able to be operated below only 400 °C by using nonequilibrium techniques to control the entropy of the chemical reactions. Therefore, this system should be recognized as a potential water-splitting technique that can widely utilize any heat sources in contrast to the conventional methods.