The effect of the volume fraction of dispersed phase on toughness of injection molded polypropylene blended with SEBS,SEPS, and SEP

The effect of the volume fraction of a dispersed phase on improvement in the toughness of injection‐molded isotactic polypropylene (i‐PP), blended with a styrenic thermoplastic elastomer, has been studied. The volume fraction of the dispersed phase, which indicates compatibility between elastomer and i‐PP, depends on the molecular structure of a soft segment and the copolymerization ratio of styrene. The volume fraction of the dispersed phase of the i‐PP blended with styrene‐ethylene‐propylene‐styrene tri‐block copolymer (SEPS) was higher than that of the i‐PP blended with styrene‐ethylene‐butylene‐styrene tri‐block copolymer (SEBS). The volume fraction of the dispersed phase increases as the copolymerization ratio of styrene increases. Improvement in the toughness of the blended i‐PP clearly depends on relaxation of strain constraint by void formation from the dispersed phase. Its efficiency proved to be dependent on the strength and the volume fraction of the dispersed phase depending on the compatibility between elastomer and i‐PP. POLYM. ENG. SCI., 45:1630–1638, 2005. © 2005 Society of Plastics Engineers     

Evaluation of the Enzymatic Saccharification Efficiency of an Energy Crop,Erianthus arundinaceus,Pretreated with Ca(OH)2 Using both Countercurrent Washing System and pH Adjustment by Nonpressurized CO2

Erianthus arundinaceus (ER) is greatly appreciated among domestic energy crops in Japan for the production of fermentable sugars from lignocellulosic polysaccharides. In this study, we developed an efficient Ca(OH)₂-based pretreatment of both stems and leaves of ER at ambient temperature with the addition of a washing step for enzymatic saccharification. The recoveries of glucans and xylans in the pretreated ER after four countercurrent washing cycles were 91 and 76 %, respectively, the former being considerably higher than that of rice straw (RS) (72 %). Their saccharification ratios in the washed sample under the pressure of 1 atm CO₂ were 80 and 92.5 %, respectively. The application of this simple sugar production process from ER would further support the domestic bioprocess development. ER is also foreseen to provide the additional feedstock favorable for harvesting from winter to spring in Japan, preventing a risk for feedstock shortage generated by single harvesting such as RS.     

Creating the hydrogen absorption capability of CeNi5 through the addition of Al

The hydrogenation capacities of CeNi_5?xAl_x (x = 0, 0.75, 1.0, 1.25, 1.5 and 1.75) alloys were assessed. In contrast to LaNi₅-based alloys, the addition of Al to CeNi₅ enables hydrogen absorption by creating larger interstitial sites as the result of an expanded lattice. Structure analyses indicate that each of these alloys maintained a CeNi₅ (CaCu₅-type) structure in which Al atoms exclusively occupied Ni 3g sites. Among these specimens, CeNi₄Al absorbed the greatest proportion of hydrogen atoms, decreasing its c/a ratio from 0.826 to 0.802 upon the formation of CeNi₄AlH_4.3. This drastic decrease in the c/a ratio is attributed to an anisotropic lattice expansion along the a-axis, as verified by in situ X-ray diffraction under H₂. The enhanced hydrogen absorption of these alloys is thought to be associated with the preferential situation of hydrogen atoms at interstitial sites located at the centers of octagons as well as a charge transition of Ce ions upon hydrogenation. It is verified that CeNi₄Al after hydrogenation shows high catalytic activity toward propyne hydrogenation: 100% conversion of propyne even at room temperature.     

Layer-by-layer growth of graphene layers on graphene substrates by chemical vapor deposition

We demonstrate a synthesis of graphene layers on graphene templates prepared by the mechanical exfoliation of graphite crystals using a developed chemical vapor deposition (CVD) apparatus that has a furnace with three temperature zones and can regulate the temperatures separately in each zone. This results in individual control over the decomposition reaction of the carbon feedstock and the growth of graphene layers by activated carbon species. CVD growth using multi-temperature zones provides wider temperature windows appropriate to grow graphene layers. We observed that graphene layers proceed by a layer-by-layer growth mode using an optical microscopy, an atomic force microscopy, and Raman spectroscopy. This result suggests that a graphene growth technique using the CVD apparatus is a potential approach for making graphene sheets with precise control of the layer numbers.     

Characterization of the Interactions between Cereal Flour and “Nata Puree” in Batter

This study aimed to characterize the interactions between cereal flour (rice, wheat, and barley) and “nata puree” (NP), a disintegrated bacterial cellulose (BC) in the presence of a water-soluble polysaccharide, with powder-dispersion activity. Pasting properties of cereal flour with additives were analyzed using a Rapid Visco Analyzer, and disintegrated BC in water (BCW), three water-soluble polysaccharides: (1,3)(1,4)-β-glucan, tamarind seed gum, and birchwood xylan, and the corresponding NPs were used as additives. For rice flour, additional BCW or NPs increased the initial and the peak viscosity. The addition of water-soluble polysaccharides produced the opposite trend: viscosity increased from the peak time to the end of measurements. For wheat flour, the addition of BCW or NP delayed the peak time and increased peak viscosity; the increase was maintained till the end of measurements. For barley flour, the additional BCW or NP caused a higher gelatinization rate and increased viscosity at the starch-retrogradation stage. Next, static gelatinization of a rice flour suspension in NP was successfully accomplished before placing it in a vessel; NP concentration in the gel significantly affected the firmness. Thus, the dynamic and unique interactions between various cereal flours and cell-wall polysaccharides in NPs can increase the flours'' potential; static gelatinization of cereal flour with NP could expand flours'' application range in both current and next-generation cooking.     

Selective oxidation of methanol in exhaust gas containing aromatic compounds

The activity of exhaust catalysts of methanol and gasoline mixture fueled automobiles is inhibited by coexistent aromatic compounds contained in the exhaust stream. One approach to avoid this inhibition could be the utilization of a molecular-sieve effect. It seems probable that the migration of aromatic compounds, which have larger molecular sizes than that of methanol, will be blocked by these supports and methanol will selectively reach the active sites of the catalysts. Thus, we examined the simultaneous oxidation of methanol and toluene over some ion-exchanged Pt/zeolite catalysts. Experimental results showed that ion-exchanged Pt/zeolite catalysts are less affected by coexistent toluene and have a higher selectivity for methanol oxidation compared with an alumina-supported platinum catalyst, suggesting that the use of these catalysts is effective for oxidizing methanol in the exhaust stream containing aromatic compounds. Among the catalysts tested, a Pt/H-MOR catalyst was found to be the most effective for the oxidation of methanol and effectively catalyzed the reaction in the presence of toluene even at low temperature.     

Fluid flow and heat transfer of natural convection at a slightly inclined,upward‐facing,heated plate

Natural convective flows over upward‐facing, inclined plates were investigated experimentally, with an emphasis on the role of opposing flows that appear over the plates inclined slightly from the horizontal line. The flow fields over the plates and the surface temperatures of the heated plates were visualized with both dye and a liquid‐crystal thermometry. The results showed that both the descending and ascending flows appeared over the plates when the inclination angles of the plates were less than 15°. The two flows collided with each other at a certain distance from the plate edge, and then detached from the plate to become a thermal plume. It was found that the above distance was determined solely by the inclination angles and was independent of sizes and heat fluxes of the plates. The local heat transfer coefficients of the plates were also measured. The results showed that the heat transfer from the plate was enhanced by the occurrence of the descending flows. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(5): 362–375, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10036     

Fluid flow and heat transfer of natural convection over upward‐facing,horizontal, heated plate shrouded by a parallel insulated plate

The present paper describes experimental results on the fluid flow and heat transfer of natural convection between a horizontal, heated plate facing upward and an insulated cover plate. The experiments were carried out with water. The width of the test plates W and their gaps H were changed from W = 50 to 250 mm and H = 10 to 30 mm and ∞ (no cover plate). The visualization studies with dye and liquid crystal thermometry revealed that the roll cells whose axes are perpendicular to the flow direction appear and become dominant over the heated plate on decreasing the gap. These roll cells inhibit the heat transfer, and thus, the heat transfer coefficients become smaller than those without a cover plate. It was found that the flow and heat transfer in the region near the plate edges are unaffected by the cover plate. The conditions of the above reduced heat transfer were determined empirically. Moreover, nondimensional correlations for the local and the overall heat transfer coefficients of the heated plates are proposed based on the present heat transfer results. © 2000 Scripta Technica, Heat Trans Asian Res, 29(4): 333–346, 2000     

A phase-interpolation direct digital synthesizer with an adaptiveintegrator

A phase-interpolation direct digital synthesizer (DDS) with an adaptive integrator is described in this paper. Unlike a conventional DDS, it does not use ROM or a D/A converter. Therefore, less power is dissipated and the maximum speed is increased. The delay time for phase interpolation is generated by the adaptive integrator, which is composed of a capacitance switch array and current switch array, and by a comparator with constant threshold voltage. The DDS was fabricated on 0.5-μm CMOS process technology. The spurious level is lower than -50 dBc and the power dissipation is 60 mW at a clock frequency of 40 MHz and output frequency of about 19 MHz     

A New Approach for Reversible RNA Photocrosslinking Reaction: Application to Sequence‐Specific RNA Selection

On and off in a flash : We describe a novel, ultrafast, reversible, interstrand RNA photocrosslinking reaction via 3‐cyanovinylcarbazole nucleoside. The interstrand RNA‐photocrosslinking reaction showed a high degree of sequence specificity and can be used in the selection of a target RNA sequence.