Compound class specific 14C analysis of polycyclic aromatic hydrocarbons associated with PM10 and PM1.1 aerosols from residential areas of suburban Tokyo

Compound class specific radiocarbon analysis (CCSRA) was performed for polycyclic aromatic hydrocarbons (PAHs) associated with airborne particulate matter (APM) with diameter <10 microm (PM10) and <1.1 microm (PM1.1) collected from a residential area of suburban Tokyo, Japan, and seasonal and particle-size radiocarbon variations were investigated. Source diagnostic isomer pair ratios indicated mixed contributions from petroleum combustion and from biomass and coal combustion to the PAHs in APM. The delta14C- PAHs in APM, ranging from -787 to -514 per thousand, indicated dominance of fossil fuel combustion. The delta14C of 5-6 rings (HMW) PAHs were higher than the 3-4 rings (LMW) species in both PM10 and PM1.1 samples. The delta14C of HMW-PAHs indicated greater biomass-burning contributions in summer than in winter and no apparent particle-size variation. Conversely, the delta14C of LMW species showed a greater contribution from fossil sources in summer and in larger particles (PM10). This finding could be tentatively attributed to the recondensation of fossil-PAHs vaporized from petroleum sources. A 14C isotopic mass balance approach estimated that biomass burning contributes 17-45% of the PAH burden in suburban Tokyo, and that the increase in the biomass-PAH accounts for approximately 27% and 22% of winter-time elevation of LMW- and HMW-PAHs, respectively. These are far exceeding what is expected from the emission statistics for CO2 and combusted materials in Japan and emphasizing the importance of biomass-burning as a source of PAHs; which, in turn, demonstrates the utility and the significance of field-based source assessment by using CCSRA for an effective regulation of atmospheric pollution by PAHs.     

多型腔注射模充填不平衡试验

多型腔注射模在实际生产中有着广泛应用,充填平衡是保证多型腔模塑制品质量均匀一致的关键。自然平衡流道中也会发生充填不平衡现象,其原因可能是熔体流动产生的剪切热所致,但一直没有试验结果予以证明。基于此,利用可视化注射模具和红外温度传感器,通过直接观测熔体在流道和型腔中的动态流动行为并测量型腔入口处熔体的温度变化,对不同注射速率下不同材料在自然平衡多型腔注射模的充填不平衡进行研究。结果表明,由于剪切热的作用,主流道中不均匀但对称的熔体温度分布在分流道中失去对称性是产生充填不平衡的根本原因;充填不平衡程度不但取决于主流道中熔体的温度分布,还取决于分流道中凝固层的分布及熔体粘度对温度变化的敏感性。解决自然平衡多型腔注射模充填不平衡问题的根本,在于改善或消除分流道中熔体温度分布在流动平面的不对称性。     

Electrodeposition of Inorganic/Organic Hybrid Thin Films

Electrodeposition of inorganic compound thin films in the presence of certain organic molecules results in self‐assembly of various hybrid thin films with new properties. Examples of new discoveries by the authors are reviewed, taking cathodic formation of a ZnO/dye hybrid as the leading example. Hybridization of eosinY leads to the formation of highly oriented porous crystalline ZnO as the consequence of dye loading. The hybrid formation is a highly complicated process involving complex chemistry of many molecular and ionic constituents. However, electrochemical analyses of the relevant phenomena indicate the possibility of reaching a comprehensive understanding of the mechanism, giving us the chance to further develop them into industrial technologies. The porous crystals are ideal for photoelectrodes in dye‐sensitized solar cells. As the process also permits the use of non‐heat‐resistant substrates, the technology can be applied for the development of colorful and light‐weight plastic solar cells.     

Prevalence of Arcobacter species in retail meats and antimicrobial susceptibility of the isolates in Japan

A survey was conducted to examine the prevalence of Arcobacter species among meat samples and to investigate the antimicrobial susceptibility of the isolates in Japan. In 1998 and 1999, samples of beef (n=90), pork (n=100) and chicken meat (n=100) were purchased from seven retail shops. Arcobacter species were isolated from 2.2%, 7.0% and 23.0% of beef, pork and chicken meat samples, respectively. The rate of isolations in chicken meats was shown to be significantly higher than those of beef and pork. Species-specific polymerase chain reaction (PCR) demonstrated that the most dominant Arcobacter species was Arcobacter butzleri among the isolates examined. Multiple contaminations with different Arcobacter species were observed in 5% of the chicken samples. Almost all the strains tested showed resistance to vancomycin (100%) and methicillin (97.5%). Strains resistant to cephalothin, sulfamethoxazole–trimethoprim, nalidixic acid and chloramphenicol were detected at the rate of 81.1%, 67.2%, 53.5% and 24.6%, respectively. All Arcobacter strains examined were susceptible to ampicillin, tetracycline, streptomycin and kanamycin.     

Direct methanol fuel cell performance of sulfonated polyimide membranes

Sulfonated polyimides (SPIs) derived from 1,4,5,8-naphthalene tetracarboxylic dianhydride, 4,4′-bis(4-aminophenoxy) biphenyl-3,3′-disulfonic acid and hydrophobic aromatic diamines showed the much lower methanol permeability and the lower proton conductivity than Nafion 112. The performance and the water and methanol crossover for direct methanol fuel cells (DMFCs) with the SPI membranes were investigated in comparison with Nafion membranes. The methanol and water fluxes increased significantly with increasing load current density for Nafion membranes but not for the SPI membranes, indicating that they were controlled by both the electro-osmotic drag and the molecular diffusion for the former but by only the molecular diffusion for the latter. These resulted in the much better DMFC performance for the SPIs than Nafion membranes especially at high methanol feed concentrations. The Faraday's efficiency and overall DMFC efficiency at 60 °C and 200 mA cm⁻² for SPI membrane with IEC of 1.51 meq g⁻¹ were 75% and 21%, respectively, at 5 wt.% methanol feed concentration, and 36% and 9.5%, respectively, at 20 wt.% methanol concentration. They were about two times and three times higher at 5 wt.% and 20 wt.% methanol concentrations, respectively, than those for Nafion 112. The short-term durability test for 300 h at 60 °C revealed no deterioration in the DMFC performance. The SPI membranes have high potential for DMFC applications at mediate temperatures (40–80 °C).     

Discontinuously reinforced aluminum: Current status and future direction

Conclusions There are now a number of important production applications for DRA, which span the transportation, aerospace, recreation, and electronics industries and that demonstrate the material’s attractive combination of structural, thermal management, an d wear properties. While large materials suppliers have mostly exited the area, many smaller suppliers are forging ahead to make DRA a success. Expanding this success depends upon the ability of researchers and engineers to continue increasing our fundamental understanding of the materials, to work together in close cooperation to transition the material, and to make the material more user friendly by publishing user handbooks, standardized property databases, and application case studies. he is the advisor to JOM from the TMS Composite Materials Committee. Warren H. Hunt, Jr., is with Aluminum Consultants Group, Inc. For more information, contact B. Maruyama, U.S. Air Force, Air Force Research Laboratory, 2230 10th Street, Suite 1, AFRL/MLLM, Wright-Patterson Air Force Base, Ohio 45433; (937) 255-1310; fax (937) 255-3007; e-mail benji.maruyama@ml.wpafb.af.mil.     

Polymer blends of polypropylene with polydialkylsiloxane

Polypropylene was blended with polydialkylsiloxane (alkyl : propyl and octyl). Some properties of the resultant polymer blends were investigated: the melt flow index at 230°C, bending modulus, and Izod impact strength. Furthermore, their morphology was observed using scanning and transmission electron microscopes. It was elucidated that polydipropylsiloxane and polydioctylsiloxane, which are finely dispersed as ciliated islands in the sea of polypropylene, are effective to increase the melt flow index and Izod impact strength of the polymer blends. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1853–1861, 1998     

An Antifungal Saponin from White Asparagus ( Asparagus officinalis L) Bottoms

An antifungal saponin was isolated from the bottom cut of white asparagus (Asparagus officinalis L), which is unusable in food processing. The structure of the saponin was identified as 3-O-[{α-L -rhamnopyranosyl (1→2)} {α-L -rhamnopyranosyl (1→4)}-β-D -glucopyranosyl] (25S) spirost-5-ene-3β-ol from chemical and spectral data. This saponin was shown to be identical with collettinside III from Dioscorea collettii, and to inhibit the growth of some kinds of fungi at μg ml⁻¹ levels.     

Characterization of BAMO/NMMO Copolymers

The compositions and microstructures, thermolyses, and sensitivities of 3,3-bis(azidomethyl)oxetane (BAMO) copolymers with 3-nitratomethyl-3-methyloxetane (NMMO) were characterized. The molar ratios of monomers fed in the copolymerizations were: BAMO/NMMO = 8/2, 7/3, and 6/4. The observed compositions were 81/19, 68/32, and 60/40, respectively. The relative compositions of trade microstructures were also exactly the same as theoretical values. The copolymerization of BAMO with NMMO behaved like an ideal system in the sense that the copolymer has approximately the same composition as the monomer fed. The microstructures of copolymers were also randomly arranged. Poly BAMO showed side chain decomposition in the initial stage of the thermolysis, on the other hand, backbone decomposition controlled the thermolysis of poly NMMO. The BAMO units and the NMMO units appeared to decompose more or less independently of one another and retained their individual decomposition characteristics despite being copolymerized. However, the heat generated by the NMMO decomposition, which occurred at 40°C lower than that of BAMO. activated the reaction of BAMO. Poly B/N(7/3) showed very interesting characteristics in sensitivities, mechanical properties, and the heat of decomposition.     

High-Tc superconductivity in entirely end-bonded multi-walled carbon nanotubes

We report that entirely end-bonded multi-walled carbon nanotubes (MWNTs) can exhibit superconductivity with a transition temperature (T_c) as high as 12 K, which is approximately 30 times greater than T_c reported for ropes of single-walled nanotubes. We find that the emergence of this superconductivity is highly sensitive to the junction structures of the Au electrode/MWNTs. This reveals that only MWNTs with optimal numbers of electrically activated shells, which are realized by end bonding, can allow superconductivity due to intershell effects.