Accelerated degradation testing of gas diffusion electrodes for the chlor-alkali process

The chlor-alkali industry consumes large amounts of energy. The gas diffusion cathode has been investigated for energy saving modifications. To commercialize the process, an electrode of high durability is required. Electrolytic operating factors causing electrode deterioration were examined. Under the condition of low oxygen concentration operation, the degradation of the electrode was significantly accelerated. The life of the electrode was also estimated by an acceleration test. The relationship between the logarithm of the life and the operating overvoltage was linear. Using this relation, the life of a possible mass production electrode was assumed to be five years or more.     

Effect of surface structure on cell growth prepared by the terminal immobilization method

Substrate effects of surface morphology and chemical structure for cell cultures prepared by molecular terminal immobilization method were studied. When we focused attention on a phenyl group as a functional moiety, the cell growth on the surface prepared by the immobilization method showed a better proliferation rate than that of a substrate prepared by the casting method. Further, from the results of mouse fibroblast L929 cell (L‐cell) growth on poly(amino acid)‐immobilized surfaces in Dulbecco's minimal essential medium containing 10% FBS, it was indicated that the amino group was more effective than the phenyl group, and that a slight difference of chemical structure had a substantial influence on cell growth. In addition, mouse bone marrow–derived Sp2/0‐Ag14 cell (Sp2/0 cell) culture in ASF‐104 serum‐free medium, poly(amino acid)‐immobilized substrates showed an almost equal proliferation rate to that in a serum‐containing medium. These results showed that effective cell growth can occur on immobilized surfaces, and that detection of a weak interaction depends on the functional groups. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3001–3008, 2004     

Nanohybrid polymer prepared by successive polymerization of methacrylate monomer containing silver nanoparticles in situ prepared under microwave irradiation

The well-dispersed silver nanoparticles were prepared in reactive methacrylate monomers under microwave irradiation without polymerization. In contrast to conventional heating, the synthesis of Ag nanoparticles proceeded uniformly throughout the reaction vessel only under microwave irradiation, reaching the completion of the reaction simultaneously in the whole reaction solution. Successive polymerization of the monomer containing the resulting nanoparticles has successfully produced a monohybrid of the silver nanoparticles dispersed in polymer matrix.     

Dehydrohalogenation during pyrolysis of brominated flame retardant containing high impact polystyrene (HIPS-Br) mixed with polyvinylchloride (PVC)

Dehydrohalogenation during pyrolysis of brominated flame retardant containing polystyrene (brominated high impact polystyrene (HIPS-Br)) mixed with polyvinylchloride (PVC) was carried out in a laboratory scale batch process. Thermal and catalytic degradation of HIPS-Br mixed with PVC on carbon composite of iron oxide (TR-00301) catalyst was investigated. The thermal degradation of waste plastics (HIPS-Br/PVC) yielded liquid products with 55,000 ppm bromine and 4300 ppm chlorine content in oil. Catalytic degradation (4 g; TR-00301) of HIPS-Br/PVC waste plastics at 430 °C produced halogen-free clean oil, which can be used as a fuel oil or chemical feedstock. The main liquid products during catalytic degradation were benzene, toluene, styrene, ethyl benzene, α-methyl styrene, butyl benzene, 1,2-dimethyl benzene etc. The average carbon number of the liquid products produced during catalytic degradation (9.3) of waste plastics was less than that of the thermal degradation (10.4) and the density of liquid products was found to be lower during the catalytic degradation than the thermal degradation. The possibility of a single step catalytic process for the conversion of halogenated waste plastics into fuel oil with the simultaneous removal of chlorine and bromine content from the oil was demonstrated.     

Preparation of luminescent nanosized NaEu(MoO<Subscript>4</Subscript>)<Subscript>2</Subscript> incorporated in amorphous matrix originated from zeolite

Novel luminescent material has been prepared by the reaction of Eu³⁺ and molybdate species in the matrix of faujasite (FAU) type zeolite X and successive calcination. Eu³⁺ exchanged FAU was reacted with MoO₃ in the solid-state at 723 K, giving a precursor. By calcining it at 1073 K, different crystalline phases were derived depending on MoO₃-loading levels. Scheelite type crystal of NaEu(MoO₄)₂ was formed at high MoO₃-loading levels, whereas europium sodalite was formed at low loading levels. For the former sample, X-ray diffraction analysis and transmission electron microscopy revealed that the nanosized NaEu(MoO₄)₂ was dispersed homogeneously within amorphous aluminosilicate matrix originated from FAU. The amorphous particles containing NaEu(MoO₄)₂ maintained the original morphology, which the starting FAU particles possessed. The emission intensity of nanosized NaEu(MoO₄)₂ in the matrix was one order higher than that of europium sodalite. The emission lifetime of nanosized NaEu(MoO₄)₂ (0.39 ms) in the matrix was longer than that of bulk NaEu(MoO₄)₂ (0.35 ms) fabricated by conventional solid-state processes.     

Hierarchical stochastic homogenization analysis of a particle reinforced composite material considering non-uniform distribution of microscopic random quantities

This paper discusses a stochastic homogenization problem for evaluation of stochastic characteristics of a homogenized elastic property of a particle reinforced composite material especially in case of considering a non-uniform distribution of a material property or geometry of a component material and its random variation. In practice, some microscopic random variations in composites may not be uniform. In this case, a non-uniformly distributed random variation of a microscopic material or geometrical property should be taken into account. For this problem, this paper proposes a hierarchical stochastic homogenization method. This method assumes that a two-phase composite material can be separated into three-scales, and propagation of the randomness through the different scales can be evaluated with the perturbation-based technique. As an example, stochastic characteristics of homogenized elastic properties of a glass-particle reinforced plastic are estimated using the proposed approach. With the numerical results, importance of the problem and validity of the proposed method are discussed.     

Migration effect on semiconductor surface for narrow-stripe selective MOVPE

Anovelmethod for deriving the migration length (L_m) on a semiconductor surface is discussed. L_m is the most important parameter but it has not been precisely investigated for narrow-stripe selective-MOVPE. L_m can be deduced from the relationship between the (111) B-facet length and the (100)-facet length in the edge-growth region formed at the side of SiO₂ masks. The two lengths have a linear relationship, so L_m on (100) surface can be obtained from an extrapolation of this relationship. This method was used to evaluate L_m for many kinds of the growth conditions. The maximum L_m and the precursors’ incorporation life-time were also deduced using the proposed method.     

Characterization of polycrystalline silicon wafers for solar cells sliced with novel fixed‐abrasive wire

For slicing crystalline silicon ingots, we have developed a novel fixed‐abrasive wire where diamond grit is fixed onto a bare wire by resin bonding. The properties of the wafers sliced using a multi‐wire saw with the fixed‐abrasive wire have been investigated. When compared with the wafers sliced with the loose‐abrasive wire, the slicing speed is improved by approximately 2.5‐fold and the thicknesses of saw‐damage layers are reduced by more than a factor of two. Polycrystalline silicon solar cells have been fabricated for the first time utilizing the wafers sliced with the fixed‐abrasive wire, and the cells with the saw‐damage etching depth of 7 µm have shown photovoltaic properties comparable to those prepared using the wafers sliced with the loose‐abrasive wire and subsequently etched to remove the damage layers up to 15 µm. It has been clarified that wafer slicing using the fixed‐abrasive wire is promising as a next‐generation slicing technique for fabrication of solar cells, particularly thin silicon cells where the wafer thicknesses approach or become less than 150 µm. Copyright © 2010 John Wiley & Sons, Ltd.     

Laboratory-performance study of quantitative PCR methods to analyze an approved genetically modified maize (Mon810 Line)

A laboratory-performance study was carried out to investigate factors affecting the reliability of the quantitative PCR method to analyze an approved genetically modified (GM) maize (Mon810 line). Test maize powdered samples were prepared as blind samples containing a high (assigned value; 5.45%) or low (assigned value; 0.35%) concentration of the Mon810 line. After confirmation of their homogeneity, they were provided to 27 laboratories participating in the collaborative study. The data were collected from all laboratories and statistically analyzed. Two laboratories, which used a Roche LightCycler (LC), reported significantly high test values. A further examination showed that the LC method is greatly affected by the equipment itself or PCR reagents, resulting in poor repeatability. On the other hand, some laboratories, which used ABI quantitative PCR equipment, reported erroneous test values. In these laboratories, the errors appeared to have been due to inadequate quality and/or yield of DNA. To identify factors affecting the test values, analysis of the measured values for the taxon-specific gene will be useful. Furthermore, the modified silica-gel membrane DNA extraction method made it possible to extract the required amounts of DNA more easily and in a shorter time than before.     

A precise on-chip voltage generator for a gigascale DRAM with anegative word-line scheme

A precise on-chip voltage generator for gigascale DRAM's with a negative word-line scheme is described. It combines a charge-pump regulator and a series-pass regulator, and it also includes a positive and negative offset voltage generator that uses a bandgap generator with a differential amplifier. The proposed circuit was experimentally evaluated with a test device fabricated using a 0.3-μm process. The simulation results show that the series-pass regulator suppresses the noise on a word-line low voltage (negative) to below 30 mV for the word-line transient and V_BB bouncing. A dc-voltage error of less than 6% without trimming is confirmed for the positive and negative offset voltage generator through the test device. These results show that the described scheme can be used in future low-voltage gigascale DRAM's