Effect of partial delignification of kenaf bast fibers for radiation graft copolymerization

Malaysian kenaf bast fiber was treated by acidic chlorite to be applied for a trunk polymer radiation‐induced graft copolymerization. The delignification conditions such as temperature, reaction time, and sodium chlorite (NaClO₂) loading were optimized from the viewpoints of density, tensile strength, and reactivity of grafting. It was found that delignification condition at 80°C for 6 h with 0.5% NaClO₂ gave 91% of lignin removal from the kenaf bast fibers. In this case, the density, fineness, and tensile strength of the kenaf fiber decreased about 46, 44, and 87%, respectively. Reactivity of grafting was evaluated using 4‐chloromethyl styrene to obtain widely available precursor materials. The partial delignified kenaf with residual lignin less than 2% resulted in degree of grafting of 134%, which is enough for precursor materials. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Detection of the carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in beer and wine

A carcinogen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), was measured in beer and wine by HPLC. PhIP was found to be present in all brands of beer and wine analyzed. The concentrations of PhIP in beer and wine were 14.1 +/- 6.18 ng/l (mean +/- SD, n = 11) and 30.4 +/- 16.4 ng/l (n = 10) respectively.     

Regional expression and subcellular localization of the tyrosine-specific phosphatase SH-PTP2 in the adult human nervous system

The protein tyrosine phosphatase SH-PTP2 has been implicated in a variety of cell signaling cascades, including those mediating neuronal survival. We therefore investigated the expression of SH-PTP2 in the adult human nervous system using Western blotting, immunohistochemistry and immunoelectron microscopy. SH-PTP2 immunoreactivity was noted only in neurons, but was not restricted to a specific neuronal type or location. Immunohistochemistry showed perikaryal staining, whereas Western blotting and ultrastructural analysis suggested that SH-PTP2 is present in axons as well. While immunohistochemistry showed a Nissl-like pattern in large motor neurons, immunoelectron microscopy demonstrated a diffuse pattern of cytoplasmic staining, without apparent preferential localization. The presence of the SH2 domain-containing tyrosine-specific phosphatase SH-PTP2 in diverse neurons in the adult nervous system suggests that SH-PTP2 may play a role in a broad spectrum of neuronal responses.     

Three-dimensional optical memory with a photorefractive crystal

We propose a three-dimensional optical-memory device in which refractive dot data are recorded directly into a photorefractive crystal. To record a single bit of datum, one focuses a laser beam with an objective lens onto a specific spot in a crystal, thereby changing its refractive index locally as a result of photorefraction. To record in three dimensions, one keeps the objective lens stationary while the crystal is translated. The beam-spot intensity is modulated with a beam shutter according to the logic state of the data point. The recorded data points are read with a phase-contrast microscope objective lens. We present experimental results of three-dimensional recording and reading with a LiNbO(3) crystal. The distribution of the refractive index formed by a focused beam is also analyzed with the charge-transport model.     

Reflection-wavelength control method for layer-by-layer controlled x-ray multilayer mirrors

A reflection-wavelength control method for a layer-by-layer controlled x-ray multilayer mirror without interface roughness is proposed. The reflection wavelength of the multiperiodic mirror is found to be simply determined by a combination ratio of periodic layers. Multiperiodic x-ray mirrors with reflectance wavelengths at 3.374 nm (C VI 1s-2p) and 3.950 nm (Ca XVIII 3d-5f) are successfully designed.     

Joining SiAlON Ceramics Using Composite β-SiAlON–Glass Adhesives

Commercial β-SiAlON ceramics were joined using mixed Si₃N₄, Y₂O₃, Al₂O₃, and SiO₂ powders. At a joining temperature of 1600°C and a hold time in excess of 10 min, the adhesive was converted to an approximate 60:40 vol% composite of β-SiAlON–glass-ceramic. The grain size of the acicular β-SiAlON grains precipitated in the joint (submicrometer diameter, average aspect ratio of 10) was significantly smaller than those in the adherend ceramic (1–5 μm diameter). Intergrowth of β-SiAlON grains at the joint interface resulted in high bond strengths. The chemistry and microstructure of the ceramic adhesives used are described.     

Stabilization of poly(vinyl chloride). III. Synergism between metal soaps and masking agents on the stabilization of poly(vinyl chloride)

The stabilization mechanism by synergetic metal soaps containing complementary colors was previously reported. With increased heating times, the color of heated poly(vinyl chloride) (PVC) films containing Cd/Ba and Zn/Ca synergetic soaps markedly deviated from the polyene color. These color deviations usually decreased the thermal stability of PVC. Discoloration from polyene color to blue appeared especially on PVC films containing Zn/Ca synergetic soap and was concomitant with a marked decrease in thermal stability. The stabilization of PVC containing synergetic metal soaps can be improved by masking or removing the excessive color. In this work, the addition of various masking agents, such as ethylenediaminetetraacetic acid, o-phenanthroline, triethanolamine, urea, N,N′ -dimethylolurea, melamine, stearylamide, and lactams, to PVC containing synergetic metal soaps was investigated. It was shown that these masking agents do markedly slow down the discoloration of PVC.     

Lubricant-Supplying Properties and Durability of Oil-Impregnated Polymers

Numerical optimization of tribological elements usually demands extended computations. The particle swarm optimization (PSO) method is known for its simple implementation and high efficiency in solving multifactor optimization problems. In this study, several parallel computing schemes using PSO for air foil bearing design are compared. The parallel programming models applied are multicore computing by OpenMP and many-core graphics processing unit (GPU) computing using Compute Unified Device Architecture (CUDA) and OpenACC. The best case was obtained when the OpenMP coding was applied at the algorithm level of optimization. The performance of CUDA was found to be compatible with OpenMP when parallel computing was used to solve the bearing model. Due to excess data communications computing using OpenACC was significantly slower than the other approaches. The parallel computing scheme recommended in this study is independent of PSO, which is applicable to tribological studies requiring global optimization analysis.     

A power spectrum approach to tally convergence in Monte Carlo criticality calculation

In Monte Carlo criticality calculation, confidence interval estimation is based on the central limit theorem (CLT) for a series of tallies from generations in equilibrium. A fundamental assertion resulting from CLT is the convergence in distribution (CID) of the interpolated standardized time series (ISTS) of tallies. In this work, the spectral analysis of ISTS has been conducted in order to assess the convergence of tallies in terms of CID. Numerical results obtained indicate that the power spectrum of ISTS is equal to the theoretically predicted power spectrum of Brownian motion for tallies of effective neutron multiplication factor; on the other hand, the power spectrum of ISTS of a strongly correlated series of tallies from local powers fluctuates wildly while maintaining the spectral form of fractional Brownian motion. The latter result is the evidence of a case where a series of tallies are away from CID, while the spectral form supports normality assumption on the sample mean. It is also demonstrated that one can make the unbiased estimation of the standard deviation of sample mean well before CID occurs.