Biocomposites Made from Short Abaca Fiber and Biodegradable Polyesters

Natural fiber‐reinforced biodegradable polyester composites were prepared from biodegradable polyesters and surface‐untreated or ‐treated abaca fibers (length ca. 5 mm) by melt mixing and subsequent injection molding. Poly(butylene succinate)(PBS), polyestercarbonate (PEC)/poly(lactic acid)(PLA) blend, and PLA were used as biodegradable polyesters. Esterifications using acetic anhydride and butyric anhydride, alkali treatment, and cyanoethylation were performed as surface treatments on the fiber. The flexural moduli of all the fiber‐reinforced composites increased with fiber content. The effect of the surface treatment on the flexural modulus of the fiber‐reinforced composites was not so pronounced. The flexural strength of PBS composites increased with fiber content, and esterification of the fiber by butyric anhydride gave the best result. For the PEC/PLA composites, flexural strength increased slightly with increased fiber content (0–20 wt.‐%) in the case of using untreated fiber, while it increased considerably in the case of using the fiber esterified by butyric anhydride. For the PLA composite, flexural strength did not increase with the fiber reinforcement. The result of soil‐burial tests showed that the composites using untreated fiber have a higher weight loss than both the neat resin and the composites made using acetylated fiber.

Flexural modulus of PBS composites as a function of fiber content.     

Resonance phenomena of a single water droplet located on a hydrophobic sheet under AC electric field

Resonance vibration of a water droplet located on the surface of a hydrophobic sheet under an AC electric field was investigated experimentally. In order to confirm the effect of the surface property of hydrophobic materials on the resonance phenomena of a water droplet, three kinds of hydrophobic materials, silicone rubber (SR), polytetrafluoroethylene (PTFE), and polydimethylsiloxane-grafted fluoropolymer (PGF) sheet were used. A single water droplet with a volume ranging from 3 to 30 /spl mu/L was placed between parallel electrodes, where a tangential electric field was formed along the surface of the hydrophobic sheet. A water droplet under the AC field vibrates strongly only at a particular frequency range. The resonance frequency, when the water droplet vibrates, decreases with increasing the volume of the water droplet. The resonance frequency on the SR sheet is lower than that on the PTFE and the PGF sheet. The resonance frequency and the magnitude of the deformation of the water droplet depend on the surface properties of the hydrophobic material.     

Rate enhancement of amines in the photopolymerization of methyl methacrylate under oxygen

The photopolymerization of methyl methacrylate was accelerated by amines such as N,N-dimethylbenzylamine, triethylamine, and diethylamine under nitrogen, in which additional initiating radicals were generated by the reaction of the amines with excited MMA. Enhanced rates were observed under oxygen for this photopolymerization in the presence of amines. Because UV spectra of the amines under oxygen indicated that the amines form charge-transfer complexes with oxygen, the rate enhancement was ascribed to photodecomposition of complexes that yield radical species. Molecular weights of polymers obtained in the photopolymerization in the presence of amines decreased under oxygen, supporting the assumed mechanism. © 1998 Society of Chemical Industry     

A redox reaction mediated by polymeric membranes containing electron carriers

A redox reaction was mediated by polymeric membranes which contain naphthoquinone derivatives as electron and proton carriers. When such a membrane containing vitamin K₁ was placed between two aqueous solutions of potassium ferricyanide and sodium dithionite, the oxidation-reduction of them took place, but the reaction was rather slow. Although vitamin K₃ was a more effective carrier and the reaction proceeded fast, the reaction rate decreased in the repeated runs. Since the reduced form of this carrier is slightly soluble in water, a part of the carrier got dissolved in the aqueous phase from the membrane during the reaction. 2-Alkyloxy-1,4-naphthoquinones such as 2-hexyloxy-1,4-naphthoquinone effectively transported electrons and protons through the polymeric membranes, promoting the membrane-mediated reaction; in these cases no retardation was observed in the repeated runs.     

Myocardial tomography with technetium-99m-tetrofosmin during intravenous infusion of adenosine triphosphate

The purpose of this study was to determine the biodistribution of 99mTc-tetrofosmin during intravenous infusion of adenosine triphosphate (ATP) and to evaluate the potential diagnostic value of myocardial tomography with 99mTc-tetrofosmin during ATP infusion for the detection of coronary artery disease. METHODS: Myocardial 99mTc-tetrofosmin imaging with ATP infusion and coronary arteriography were performed on 65 patients with suspected coronary artery disease. ATP was infused intravenously at a rate of 0.16 mg/kg/min for 5 min, and 370 MBq of 99mTc-tetrofosmin was injected 3 min after the start of ATP infusion. Myocardial SPECT imags were obtained 60 min later. Then, 740 MBq of 99mTc-tetrofosmin was administered at rest, and myocardial SPECT was repeated. Regional uptakes of 99mTc-tetrofosmin were scored from 4, normal, to 0, no activity. Serial 5-min planar images were obtained in the anterior projection at 15, 30, 45 and 60 min after the 99mTc-tetrofosmin injection in 10 patients. Heart-to-lung and heart-to-liver count ratios were defined from the serial planar images. RESULTS: Adverse effects of ATP infusion were mild and transient. A heart-to-lung ratio after ATP infusion was high even at 15 min (3.40 +/- 0.33) and gradually increased with time. A heart-to-liver ratio after ATP was 0.53 +/- 0.40 at 15 min and increased with time. A heart-to-liver ratio reached 0.99 +/- 0.25 (p < 0.01) after 45 min and 1.32 +/- 0.36 (p < 0.01) after 60 min. The sensitivity and specificity for detecting coronary artery disease by myocardial SPECT with ATP were 89% (39/44) and 86% (18/21), respectively. CONCLUSION: This study shows the favorable biodistribution of 99mTc-tetrofosmin after intravenous infusion of ATP. A one-day imaging protocol of 99mTc-tetrofosmin tomography with ATP is feasible and has high diagnostic accuracy for coronary artery disease.     

Tritium retention to the first wall of JT-60U

For economic and safety reasons, tritium (T) accumulation on plasma facing wall (PFW) of fusion reactor is strictly limited. In this study, T inventory in the graphite tiles used at the first wall of JT-60U was measured by a full combustion method. It was found that T was only retained near plasma facing surfaces sides of the tiles and the amount of retained T increased from <10¹¹ to <10¹³ T atoms/cm² with increasing the exposed discharge period of the tiles. Integrating the T retention with the total surface area of the outer first wall tiles, the fraction of retained T in that area was estimated to be 13% of the total T production. It was confirmed that these retained T were part of the energetic T produced by DD reactions without being replaced by HH discharges. Based on the retained fraction, the annual amount of T retention in the outer first wall of a demo-size reactor was calculated to be 360 g/burn-year at maximum. Even the value would be much less in the reactor, the accumulation of this kind of inventory could have significant contribution to the total T inventory.     

Direct conversion of methane into methanol over MoO3/SiO2 catalyst in an excess amount of water vapor

Well-dispersed MoO₃ on SiO₂ showed a high activity for partial oxidation of methane (mixed with oxygen in a molar ratio of 9:1) into methanol and formaldehyde at 873 K in an excess amount of water vapor, which is attributed to the formation of silicomolybdic acid (SMA) on the catalyst surface during reaction. One of the roles of SMA for the partial oxidation of methane is proved to depress the successive oxidation of methanol and formaldehyde into carbon oxides.     

Effective microbial production of poly(4‐hydroxybutyrate) homopolymer by Ralstonia eutropha H16

The effective microbial production of copolyesters of 3‐hydroxybutyrate (3HB) and 4‐hydroxybutyrate (4HB) with high mole fractions of 4HB units by a wild‐type strain of Ralstonia eutropha H16 was investigated in culture solutions containing 4‐hydroxybutyric acid (4HBA) and various carbon substrates in the presence of a nitrogen source such as ammonium sulfate. The addition of glucose or acetic acid to the culture solution containing 4HBA in the presence of ammonium sulfate resulted in the production of random copolymers of P(3HB‐co‐4HB) with compositions of up to 82 mol% 4HB, but the yield of copolymers was less than 7 wt% of dried cell weights. In contrast, when n‐alkanoic acids such as propionic acid, butyric acid, valeric acid and hexanoic acid, being subject to β‐oxidation metabolism in the cell, were used as the co‐substrates of 4HBA in the presence of ammonium sulfate, a mixture of copolymers with two different 4HB compositions was produced, and copolyesters with compositions of 93–100 mol% 4HB were isolated from chloroform–n‐hexane insoluble fractions in the mixture of copolymers. Especially, when this wild‐type Ralstonia eutropha H16 was cultivated in a medium containing 4HBA (15 g litre⁻¹), propionic acid (5 g litre⁻¹) and ammonium sulfate (5 g litre⁻¹), namely C/N (mol/mol) = 10, the P(4HB) homopolymer was produced at maximally 34 wt% of dry cell weight (7.8 g litre⁻¹), and the conversion yield of 4HBA to P(4HB) homopolymer resulted in values as high as 21 mol%. © 1999 Society of Chemical Industry     

High-speed blanking of an amorphous alloy

An amorphous foil of 28 μum in thickness has been blanked at various blanking speeds, ranging from 0.06 m/s to 15 m/s. A mechanical press is used for the range of 0.06–0.22 m/s, and an electromagnetically actuated press for the higher range of up to 15 m/s. The clearance has been changed also, between 1.0 μum and 5.0 μum. The effects of blanking speed clearance and number of blankings on the blanked surface have been investigated. Furthermore, crystallization of the blanked surface has been examined with the use of the electron beam diffraction method. Crystallization has been found to take place mainly at the burnished area, very little being found at the fractured area and the vein-pattern area.     

Surfactant effects on heterogeneous polymer reaction: Nucleophilic substitution of poly(vinyl chloride) in water

The reactions of poly(vinyl chloride) (PVC) with some nucleophiles such as azide, thiophenoxide and dithiocarbamate ions do not take place in water. These heterogeneous reactions are remarkably catalyzed by cationic surfactants. Urea and methanol which destroy hydrophobic bondings inhibit the reaction. On the basis of the experimental data it was assumed that the cationic surfactants are adsorbed on the surface of the suspended PVC powder and that the positive charges attract the nucleophiles.