Rapid Vapor Grown Carbon Fiber Production Using the Intermittent Liquid Pulse Injection Technique

Three series of experiments were conducted to collect information for the design of a commercial scale reactor for the production of low cost vapor grown carbon fibers (VGCFs). Firstly, the effects of reaction conditions on the yield of vapor grown carbon fibers were investigated using the newly developed liquid pulse injection technique. The examined conditions were the flow rate of the carrier gas, and the amount of the catalyst source injected into the reactor as a liquid pulse. Yields up to 40% were attained under optimized conditions. Secondly, VGCFs were continuously produced by intermittently injecting the catalyst source into the reactor (intermittent liquid pulse injection technique), and the effect of the intervals of the injections on the amount of VGCFs obtained was also investigated. VGCFs were successfully obtained using this method. Finally, the growth sequences of VGCFs were investigated using benzene, toluene and xylene as the carbon source. VGCFs were obtained from each carbon source     

Properties of Phosphorus‐Doped Silicon‐Rich Amorphous Silicon Carbide Film Prepared by a Solution Process

Using a polymeric precursor synthesized from a mixture of cyclopentasilane, white phosphorus, and 1‐hexyne, we deposited phosphorus‐doped silicon‐rich amorphous silicon carbide (a‐SiC) films via a solution‐based process. Unlike conventional polymeric precursors, this polymer requires neither catalysts nor oxidation for its synthesis and cross‐linkage. Therefore, the polymeric precursor is sufficiently pure for effective doping and fabricating semiconducting a‐SiC. This study presents the results of a detailed study of the effect of carbon and phosphorus concentrations on the structural, optical, and electrical properties of a‐SiC films. The lowest activation energy for these films is 0.39 eV, which leads to an optical gap and a dark conductivity of 2.1 eV and 10⁹ Ω cm, respectively. Moreover, these films satisfy the Meyer–Neldel rule for thermally activated conductivity, which indicates that white‐phosphorus doping of solution‐processed a‐SiC produces films with the same characteristics as phosphine‐doped vacuum‐processed a‐SiC.     

Angled long tip to tuning fork probes for atomic force microscopy in various environments

We expand the range of applications of a tuning fork probe (TFP) in frequency-modulation atomic force microscopy (FM-AFM) by attaching a long metal tip at a certain angle. By the combined flexure of the metal tip and the tuning fork prong, this TFP can change the direction of the detectable force by switching the resonance frequency, which has not been realized with conventional TFPs with short tips. The oscillatory behavior of the tip apex of the TFP is predicted by computer simulations and is experimentally confirmed with scanning electron microscope. FM-AFM operations using this TFP are performed in various environments, i.e., in ultrahigh vacuum, air, and water. FM-AFM images obtained at an atomic step of highly oriented pyrolytic graphite in air show a clear difference depending on the excitation frequency. It is also revealed that the higher order flexural modes of this TFP are advantageous for FM-AFM in water due to the reduction in the degree of hydrodynamic damping.     

Tensile behavior of glass‐fiber‐filled polyacetal: Influence of the functional groups of polymer matrices

We investigated the tensile behavior of glass‐fiber‐filled polyacetal [i.e., polyoxymethylene (POM)], focusing on the mutual influence of the functional groups in the POM matrices and the glass binder system. The different POM matrices were compounded with three kinds of glass fibers (20 wt %) treated with different glass binders, namely, epoxy resin, thermoplastic polyurethane (TPU), and a mixture of TPU and epoxy resin. A good correlation between the tensile strength and elongation at break was observed, regardless of the difference in the glass binders. The composites based on the modified POM matrix, which had both a carboxyl end group and a hydroxyl end group, improved the tensile properties noticeably in comparison with those based on the normal POM matrix. The composites were strengthened with an increase in the concentration of the functional groups. The results of scanning electron microscopy observations indicated that the fractured surfaces of a specimen having maximum tensile strength and elongation exhibited cohesion of the modified POM on the surfaces of the glass fibers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Synthesis and charge/discharge properties of cellulose derivatives carrying free radicals

Ethyl cellulose derivatives [EC-T and EC-P] and cellulose acetate derivatives [CA-T and CA-P] carrying TEMPO or PROXY radicals (TEMPO = 2,2,6,6-tetramethyl-1-piperidinyloxy, PROXY = 2,2,5,5-tetramethyl-1-pyrrolidinyloxy) were synthesized with moderate number-average molecular weights of 62?400-126?000 in 84-88% yield by the reaction of 4-carboxy-TEMPO or 3-carboxy-PROXY with residual hydroxyl group of ethyl cellulose or cellulose acetate. All the free radical-containing cellulose derivatives demonstrated reversible charge/discharge processes, whose discharge capacities were 42.8-61.1 A h/kg. In particular, the CA-T-based cell displayed two-stage discharge process, and the first-stage discharge capacity reached 29.5 A h/kg which corresponds to 74% of its theoretical value, and that of the total capacity was 61.1 A h/kg which approaches up to 153% of the theoretical value for one-electron redox reaction.     

Cholesterol-lowering activity of plant sterol-egg yolk lipoprotein complex in rats

Free plant sterols cannot be dissolved in oil or water. Using free plant sterols and egg yolks, we developed a plant sterol-egg yolk lipoprotein complex (PSY) that can be dispersed in water and considered suitable for use in processed foods. The cholesterol-lowering activity of PSY was equal to that of free plant sterols and plant sterol esters. Consumption of a freeze-dried PSY-containing omelet reduced serum and hepatic cholesterol concentrations. The results suggest that PSY has cholesterol-lowering activity equivalent to that of free plant sterols and plant sterol esters. Moreover, the cholesterol-lowering activity of PSY was maintained in processed foods.     

Degradation of bisphenol A using sonochemical reactions

The sonochemical degradation of bisphenol A in aqueous solution, a suspected endocrine disruptor, which can cause several damages for humans, animals and the environment, was investigated at different ultrasonic intensities under air atmosphere. Bisphenol A (0.50mM) was completely degraded after 10, 3 and 2h of ultrasonic irradiation at a frequency of 404kHz, and intensities of 3.5, 9.0 and 12.9kW/m(2), respectively. During ultrasonic irradiation, some aromatic intermediates such as 2-(4-hydroxyphenyl)-2-(3,4-dihydroxyphenyl)propane, commonly known as 3-hydroxybisphenol A were detected. Further cleavage of the aromatic rings resulted in other products, like formaldehyde and organic acids, also being detected. The proposed pathways of bisphenol A degradation by ultrasonic irradiation are based on the above-mentioned intermediates. The relationship between bisphenol A degradation and formation of hydrogen peroxide and nitric acid was taken into account, correlating this to the radicals that take part in the degradation process. In order to optimize the performance of the ultrasonic system, additional experiments using Fenton-like reactions were also carried out. However, the addition of iron (II) sulfate (FeSO(4)) did not increase bisphenol A degradation rates. Compared with the system without iron (II) sulfate, the total organic carbon concentration (TOC) was reduced by about 30%, at 404kHz and 9.0kW/m(2).     

Effects of processing additives on nanoscale phase separation,crystallization and photovoltaic performance of solar cells based on mesogenic phthalocyanine

A study on the effects of processing additives on the nanoscale phase separation, crystallization, and photovoltaic performance of bulk heterojunction (BHJ) thin films made of 1,4,8,11,15,18,22,25-octahexylphthalocyanine (C6PcH₂) and [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) via spin-casting for photovoltaic applications is reported. By incorporating various solvents as processing additives to a volume of a few percent, the separation of donor and acceptor phases in C6PcH₂:PCBM thin films, which discussed by taking the photoluminescence quenching, Davydov splitting at the Q-band of the absorbance spectra and the surface nanomorphology into consideration, is improved, and the crystallinity of the discotic C6PcH₂ molecules with hexagonal structures is reinforced. Photovoltaic cells with the optimum phase-separated BHJ materials and high crystallinity of the discotic C6PcH₂ molecules are demonstrated to have a power conversion efficiency of 4.2%.     

Liquid-phase diffusivity of benzene within mesoporous materials measured by a laser Raman technique

The intracrystalline diffusivities of benzene within a series of porous materials in the liquid phase (cyclohexane was used as solvent) were measured by a constant volumetric method using Raman spectroscopy at a temperature range from 323 to 393 K. Silicalite-1, mono-dispersed mesoporous silica spheres (MMSS), silica gel, γ-Al₂O₃, and SiO₂–Al₂O₃ were used as adsorbents. The intracrystalline diffusivity was calculated by parameter fitting using theoretical equations and the experimental transient change of benzene concentrations with time in response to the adsorption. The intracrystalline diffusivities of benzene within mesoporous silicas were almost the same as that within the micropore of silicalite-1, though the pore diameters of silicalite-1 and mesoporous silicas were different from each other. It is considered that the pore walls as well as the solvent molecules of cyclohexane affect the diffusion of benzene molecules in the mesopore region.     

Effects of impurity elements on solidification cracking in electron beam welding of pipeline steel. Study of all‐position electron beam welding of large diameter pipeline joints (3rd report)

Over the last decades the arsenal of highly-effective welding technologies has been supplemented by new ones, called hybrid technologies. In this paper, we characterize hybrid welding technologies such as laser-electric arc, laser-plasma, light beam-laser and laser-submerged arc as well as hybrid ‘cold’ technologies of manufacture of permanent joints, i.e. mechanical fastenings (clamped and riveted joints) and glue joints, including also mechanical-glue ones.