Narrow multi-walled carbon nanotubes produced by chemical vapor deposition using graphene layer encapsulated catalytic metal particles

The use of graphene layer encapsulated catalytic metal particles for the growth of narrower multi-walled carbon nanotubes (MWCNTs) has been studied using plasma-enhanced chemical vapor deposition and conventional thermal CVD. Ni–C or Fe–C composite nanoclusters were fabricated using the dc arc discharge technique with metal–graphite composite electrodes carrying a current of 100–200 A in a stainless-steel chamber filled with He and CH₄ mixture gas at 27 kPa. Nano-sized grains with diameters less than 10 nm were fabricated and deposited on a Si substrate, and were used as a catalyst for MWCNT growth. Structural analyses of the composite nanoclusters and MWCNTs were carried out using transmission electron microscopy. The results show that the diameters of the MWCNTs were reduced from 50–100 nm for a conventional Ni thin film-evaporated Si substrate to a minimum of roughly 2–4 nm in the present study.     

Porous cellulose acetate membrane prepared by thermally induced phase separation

Microporous cellulose acetate membranes were prepared by a thermally induced phase separation (TIPS) process. Two kinds of cellulose acetate with acetyl content of 51 and 55 mol % and two kinds of diluents, such as 2‐methyl‐2,4‐pentandiol and 2‐ethyl‐1,3‐hexanediol, were used. In all polymer‐diluent systems, cloud points were observed, which indicated that liquid–liquid phase separation occurred during the TIPS process. The growth of droplets formed after the phase separation was followed using three cooling conditions. The obtained pore structure was isotropic, that is, the pore size did not vary across the membrane. In addition, no macrovoids were formed. These pore structures were in contrast with those usually obtained by the immersion precipitation method. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3951–3955, 2003     

<Emphasis Type="Italic">Brassica rapa</Emphasis> var. <Emphasis Type="Italic">japonica</Emphasis> Leaf Extract Mediated Green Synthesis of Crystalline Silver Nanoparticles and Evaluation of Their Stability,Cytotoxicity and Antibacterial Activity

Silver nanoparticles (AgNPs) were successfully synthesized from the reduction of Ag⁺ using AgNO₃ solution as a precursor and Brassica rapa var. japonica leaf extract as a reducing and capping agent. This study was aimed at synthesis of AgNPs, exhibiting less toxicity with high antibacterial activity. The characterization of AgNPs was carried out using UV–Vis spectrometry, energy dispersive X-ray spectrometry, fourier transform infrared spectrometry, field emission scanning electron microscopy, X-ray diffraction, atomic absorption spectrometry, and transmission electron microscopy analyses. The analyses data revealed the successful synthesis of nano-crystalline Ag possessing more stability than commercial AgNPs. The cytotoxicity of Brassica AgNPs was compared with commercial AgNPs using in vitro PC12 cell model. Commercial AgNPs reduced cell viability to 23% (control 97%) and increased lactate dehydrogenase activity at a concentration of 3 ppm, whereas, Brassica AgNPs did not show any effects on both of the cytotoxicity parameters up to a concentration level of 10 ppm in PC12 cells. Moreover, Brassica AgNPs exhibited antibacterial activity in terms of zone of inhibition against E. coli (11.1?±?0.5 mm) and Enterobacter sp. (15?±?0.5 mm) which was higher than some previously reported green-synthesised AgNPs. Thus, this finding can be a matter of interest for the production and safe use of green-AgNPs in consumer products.     

Effects of the introduction of the discrete energy loss process into Monte Carlo simulation of electron scattering

First, the single scattering model is briefly described. Next, the hybrid model is explained, which takes into consideration a part of the discrete energy loss processes. The Vriens or the Gryzinski cross section is used for core electron ionizations, and the Moller cross section for free electron excitations. The model is applied to the calculations of the energy distribution of transmitted electrons through a thin film and the depth distribution of generated x-rays. From comparisons among the calculated results with and without energy straggling and experimental data, it is found that the Gryzinski cross section shows the best result.     

高El和高λ型980MPa级冷轧钢板的特性

近年来,超高强度薄钢板越来越多地用于汽车车身部件,以提高汽车冲撞安全性和减轻车身重量,从而减少气体排放,保护环境。为适应这种需求．神户制钢已开发出几种980MPa级冷轧薄钢板。介绍了新开发的两种980MPa级冷轧薄钢板的特点：由于延展性和拉伸凸缘性的良好匹配而具有优良的成形性,同时还具有包括焊接性和化成处理性在内的良好的应用性能。     

Characterization of new types of mannosylerythritol lipids as biosurfactants produced from soybean oil by a basidiomycetous yeast, Pseudozyma shanxiensis

Mannosylerythritol lipids (MELs) are glycolipid biosurfactants produced by the yeast strains of the genus Pseudozyma. These show not only the excellent surface-active properties but also versatile biochemical actions. In course of MEL production from soybean oil by P. shanxiensis, new extracellular glycolipids (more hydrophilic than the previously reported MELs) were found in the culture medium. As a result of the structural characterization, the glycolipids were identified as a mixture of 4-O-[(2', 4'-di-O-acetyl-3'-O-alka(e)noyl)-beta-D-mannopyranosyl]-D-erythritol and 4-O-[(4'-O-acetyl-3'-O-alka(e)noyl-2'-O-butanoyl)-beta-D-mannopyranosyl]-D-erythritol. Interestingly, the new MELs possessed a much shorter chain (C(2) or C(4)) at the C-2' position of the mannose moiety compared to the MELs hitherto reported, which mainly possess a medium-chain acid (C(10)) at the position. They would thus show higher hydrophilicity and/or water-solubility, and expand the development of the environmentally advanced yeast biosurfactants.     

Microbial conversion of glycerol into glycolipid biosurfactants, mannosylerythritol lipids, by a basidiomycete yeast, Pseudozyma antarctica JCM 10317(T)

Microbial conversion of glycerol into functional bio-based materials was investigated, aiming to facilitate the utilization of waste glycerol. A basidiomycete yeast, Pseudozyma antarctica JCM 10317, efficiently produced mannosylerythritol lipids (MELs) as glycolipid biosurfactants from glycerol. The amount of MEL yield reached 16.3 g l(-1) by intermittent feeding of glycerol.     

Microstructural Changes During Plastic Deformation and Corrosion Properties of Biomedical Co-20Cr-15W-10Ni Alloy Heat-Treated at 873 K

Metallurgical and Materials Transactions A - Microstructural changes were observed during the plastic deformation of ASTM F90 Co-20Cr-15W-10Ni (mass&nbsp;pct) alloy heat-treated at...     

Relationship between microstructure and magnetic domain structure of Nd--Fe--B melt-spun ribbon magnets

The relation between the microstructure, observed using an electron probe microanalyzer, and the domain structure, observed using a Kerr microscope, was established to evaluate the effects of hot rolling and the addition of Ti--C on the c-axis orientation and the magnetization process of hot-rolled Nd--Fe--B--Ti--C melt-spun ribbons. The addition of Ti--C promotes the c-axis orientation and high coercivity in the ribbons. Elemental mapping suggests a uniform elemental distribution; however, an uneven distribution of Ti was observed in an enlarged grain with Ti-enriched points inside the grain. The reversal domains that nucleated at the Ti-enriched point inside the grain cause low coercivity.