用粉末注射成形(PIM)制造高性能烧结材料

这篇论文主要研究了用粉末注射成形工艺制造各种高性能与功能烧结材料时，需要的显微组织控制。     

Flame retardancy effects of halogenated phosphates on poly(ethylene terephthalate) fabric

A Chemical research on the flame retardancy effect of halogenated phosphates on poly(ethylene terephathalate) fabric was carried out by thermogravimetry, infrared spectral analysis, and mass spectrometry. The following conclusions were drawn: (1) The flame retardancy effect of halogenated phosphates such as tris(2,3-dibromopropyl) phosphate is due to altering the pyrolysis reaction of polyester by aldol condensation. (2) The probability that liberated halogen compounds from the phosphates act as radical acceptors in a flame zone may be low. (3) Incorporation of halogen elements into phosphates appear to depress evaporation of phosphates, which act as acidic catalysts in aldol condensation from the condensed phase.     

Internal gravity wave resonance of thermal convection fields in rectangular cavities with heat‐flux vibration (effects of aspect ratio on the fields)

In this paper the thermal convection field and its resonance phenomena in a rectangular cavity with heat‐flux vibration are numerically examined and the results are compared with those of a square cavity. As in the case of α=1, the critical angular velocity at which the relative amplitude of the midplane Nusselt number α_m has a local maximum agrees very well with the resonance angular velocity of the internal gravity wave ω_r, estimated by the theoretical equation proposed by Thorpe, even when the aspect ratio is α=5 and the Prandtl number is Pr=0.71 for a range of the Rayleigh number Ra. However, α_m has two local maxima for a larger Ra, which is peculiar to the case of larger α. The time variation of sub‐components of the fluctuating component of the midplane Nusselt number shows that the phase at the maximum value of α_m agrees well with that of the sub‐component of velocity for the first resonance angular velocity ω_r. For the other angular velocity ω_r2, the phase of α_m agrees with that of the sub‐component of temperature. Moreover, we found that the boundary angular velocity ω₀ between the first two of the five ω regions, which classify the thermal convection fields against ω, can be expressed by a function of α, Ra, and Pr and that α_m is independent of α and Ra for a relatively wide range of ω/ω₀. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(3): 158– 171, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20149     

Purification and characterization of extracellular 1,2-alpha-L-fucosidase from Bacillus cereus

Bacillus cereus isolated from a soil sample, inductively produced alpha-L-fucosidase in culture medium containing porcine gastric mucin (PGM). The production of the enzyme was also weakly induced by L-fucose and D-arabinose, but not by other sugars including glucose. The enzyme was purified 61-fold with an overall recovery of 1.8% from the culture fluid supplemented with PGM by ammonium sulfate precipitation, acetone fractionation, and subsequent column chromatography. The purified enzyme was found homogeneous by SDS-PAGE and its molecular mass was estimated to be approximately 196,000 kDa. Its optimum pH was 7.0 and it was stable in the pH range of 5.0 to 9.0. The enzyme hydrolyzed the alpha-(1-->2)-L-fucosidic linkage in oligosaccharides such as Fucalpha1-2Galbeta1-4Glc (2'-fucosyllactose), Fucalpha1-2Galbeta1-3GlcNAcbeta1-3Galbeta1-4Glc (lacto-N-fucopentaose I), and the glycoprotein PGM. The enzyme was inactive on p-nitrophenyl alpha-L-fucoside, the alpha-(1-->3)-L-fucosidic linkages in Galbeta1-4(Fucalpha1-3)GlcNAcbeta1-3Galbeta1-4Glc (lacto-N-fucopentaose III) and orosomucoid, the alpha-(1-->4)-L-fucosidic linkage in Galbeta1-3(Fucalpha1-4)GlcNAcbeta1-3Galbeta1-4Glc (lacto-N-fucopentaose II), and the alpha-(1-->6)-L-fucosidic linkage in thyroglobulin.     

Flotation of blue-green algae using methylated egg ovalbumin

The removal of blue-green algae by dispersed gas flotation was conducted. Methylated ovalbumin (MeOA) was used as frother and flocculant, which is a biodegradable substance. The continuous flotation experiments were conducted at different feed mass flow rate of the blue-green algae cells and MeOA. The operating variables were the mass flow rate of blue-green algae cell and MeOA, the initial concentration of the cells and MeOA, and superficial gas velocity. The results showed that the mass flow rate of MeOA was the most dominant variable affected by the removal efficiency and that the removal efficiency achieved ca. 0.85 when a ratio of the mass flow rate of MeOA and that of the cells was over 0.3. A proposed flotation model considering the adsorptions of MeOA to the cells, MeOA to bubble surface and the cells bearing with MeOA to bubble surface was applied to explain the experimental removal efficiency. The experimental and the calculated removal efficiency were within error 19%, indicating that the proposed model was valid fundamentally.     

Studies on fish scale collagen of Pacific saury (Cololabis saira)

We purified and characterized Type I collagen from the scales of the Pacific saury (Cololabis saira) and compared it with collagen from other organisms. Subunit composition of C. saira collagen (2α1 + α2) was similar to that of red sea bream (Pagrus major) and porcine collagen. C. saira collagen did not form a firm gel after neutralization of pH in solution. The temperature of denaturation (24–25 °C) of C. saira collagen was slightly lower than that of P. major collagen (26–27 °C). The contents of proline and hydroxyproline were lower in red sea bream and Pacific saury collagen than in porcine collagen. Circular dichroism spectra and Fourier-transformed infrared spectra showed that heat denaturation caused unfolding of the triple helices in all three collagens.     

Identification of the Sex Pheromone Secreted by a Nettle Moth, Monema flavescens, Using Gas Chromatography/Fourier Transform Infrared Spectroscopy

The nettle moth Monema flavescens (Limacodidae) is a defoliator of fruit trees, such as Chinese plum and persimmon. The larvae of this species have spines containing a poison that causes serious irritation and inflammation in humans. Coupled gas chromatography-electroantennogram detection and gas chromatography/mass spectrometry analyses of a crude pheromone extract, combined with derivatization, indicated that female moths produced 8-decen-1-ol and 7,9-decadien-1-ol at a ratio of approximately 9:1. The E configuration of the double bonds was assigned for both components from infrared spectra, recorded on a gas chromatograph/Fourier transform-infrared spectrophotometer equipped with a zinc selenide disk cooled to ?30 °C. The monoenyl and dienyl alcohols had absorptions characteristic of E geometry at 966 and 951 cm^?1, respectively. A band chromatogram at 951 cm^?1 was useful for distinguishing geometric isomers, because terminal conjugated diene are difficult to resolve, even on high polarity columns. Furthermore, we identified the Z configuration of the same 7,9-dienyl alcohol secreted by another nettle moth, Parasa lepida lepida, through the absence of this absorption. In field trials, lures baited with a 9:1 mixture of (E)-8-decen-1-ol and (E)-7,9-decadien-1-ol attracted M. flavescens males. Furthermore, the field trials indicated that contamination with the (Z)-diene reduced catches to the pheromone mixture more than did contamination with the (Z)-monoene.     

Improvement of optical nonlinear response in GaAs/AlGaAs nipi-MOW structure with Au ohmic contact

Experiments demonstrate that the optical nonlinear response in a GaAs/AlGaAs nipi-MQW structure can be improved by introducing ohmic contacts, which electrically connect n- and p-layers. The response time is reduced by more than two orders of magnitude because of the enhanced recombination rate of photoexcited carriers, whereas the figure of merit for absorptive nonlinearity sigma /sub eh/ is kept constant and is an order of magnitude larger than that in a conventional GaAs/AlGaAs MQW structure.<>     

A highly non-stereospecific catalyst for propene polymerization

Summary The MgCl₂-supported TiCl₃ catalyst containing a small amount of Ti(about 0.1 wt.%) was prepared by treating the mixture of MgCl₂ and TiCl₃ 3py with an excess amount of AlEt₂Cl. Propene polymerization was conducted at 40°C by using AlEt₃ as cocatalyst. The catalyst system was found to be highly active, which gave atactic polypropylene     

Nonlinear absorption in n-i-p-i-MQW structures

Absorptive nonlinearity in a GaAs/AlGaAs n-i-p-i-MQW (multiple quantum well) structure consisting of alternating n-AlGaAs, i-GaAs/AlGaAs MQW, and p-AlGaAs layers is investigated. A change in the absorption coefficient of more than 4000/cm is obtained in the i-MQW layer with an extremely low excitation intensity on the order of 1 mW/cm ². The figure of merit for absorptive nonlinearity, σ _ch, defined as the change in the absorption coefficient induced by excitation of an electron-hole pair per unit volume, is experimentally evaluated to be 7×10^-13 cm², which is an order of magnitude larger than that for saturation of excitonic absorption in a conventional MQW structure. This experimental value agrees well with the theoretical estimation, which is calculated assuming an optical nonlinear process