Poly(2,6-dihydroxy-1,4-oxyphenylene

A new poly(phenylene ether) derivative, poly(2,6-dihydroxy-1,4-oxyphenylene), was synthesized by demethylation of poly(2,6-dimethoxy-1,4-oxyphenylene) with an excess of boron tribromide in methylene chloride. The resulting polymer was soluble in N,N-dimethylformamide, dimethyl sulfoxide, and acetone, however, insoluble in chloroform, methanol, and benzene. NMR and IR analyses showed that the extent of the demethylation was 93% and the polymer was composed of 2,6-dihydroxy-1,4-oxyphenylene unit. The polymer was stable below 300 °C under nitrogen. Received: 20 November 1996/Accepted: 28 November 1996     

Effect of paddle rotational speed on particle mixing behavior in electrophotographic system by using parallel discrete element method

The objective of this paper is to investigate the effect of paddle rotational speed on the mixing behavior in an agitation process of an electrophotographic system by using parallel DEM. The mixing behaviors of beads with different sizes and densities were measured at various paddle rotational speeds by using a high-speed video camera, and were compared with the simulation results. A good agreement in the mixing behavior was obtained and the changes in particle velocity during the mixing were comparable. The simulation for mixing behavior of larger carrier particles suggested that the radial particle mixing was much faster than the axial one. The faster radial mixing is attributed to the fact that there are two radial flows in the system; the one is over the shaft, the other is between the paddle and shaft. The extent of mixing depended on the number of paddle rotations when the rotational speed is larger than 100 rpm, while the mixing under 50 rpm is completed at a smaller number of rotations.     

Alleviation of monocrotaline-induced pulmonary hypertension by antibodies to monocyte chemotactic and activating factor/monocyte chemoattractant protein-1

Administration of monocrotaline (MCT) causes pulmonary vascular lesions consisting of monocyte/macrophage infiltration in the early phase and medial thickening in pulmonary arteries and arterioles associated with pulmonary hypertension (PH) in the later phase. However, the molecular mechanism of monocyte/macrophage infiltration and its roles remain elusive. Herein, we have evaluated the role of a potent monocyte chemotactic and activating chemokine/monocyte chemoattractant protein-1 (MCAF/MCP-1) in MCT-induced PH in rats. A single injection of MCT induced PH at Day 21, as evidenced by increases in the ratio of right ventricular to left ventricular and septum weights (RV/LV+S) and right ventricular systolic pressure (RVSP). A significant increase in macrophage number in lungs started at Day 14, reaching a maximum at Day 21. MCAF/MCP-1 levels in bronchoalveolar lavage fluids were elevated significantly at Day 14 and remained high until Day 28, whereas plasma MCAF/MCP-1 levels increased at Day 7, returning to normal levels by Day 21. Immunoreactive MCAF/MCP-1 proteins were mainly detected in macrophages in alveoli and in perivascular regions of pulmonary arterioles and venules. Intravenous administration of anti-MCAF/MCP-1 antibodies with MCT significantly decreased macrophage infiltration and eventually reduced the increases in RV/LV+S and RVSP, as well as medial thickening of pulmonary arterioles. Thus, MCAF/MCP-1 is essentially involved in MCT-induced PH by recruiting and activating macrophages.     

Photoluminescence characterization of β-FeSi2 prepared by ion beam sputter deposition (IBSD) method

Photoluminescence (PL) measurement technique was found to be effective in revealing the unique characteristics of β-FeSi₂ film formation on Si substrates by means of ion beam sputter deposition (IBSD) method. A strong photoluminescence peak at around 0.8 eV was observed for β-FeSi₂ samples and also for Si substrates that were sputter etched by Ne⁺, and then thermally annealed in air at elevated temperature. Comparison with literature data indicated that the PL peak at 0.8 eV observed in this study was mainly from D1 emission bands in Si substrate, whose intensity was enhanced by the sputter etching and the subsequent annealing of the substrate. Furthermore, comparison between CZ-Si and FZ-Si results indicated that the energy of 0.8 eV peak observed in this study was affected by the presence of oxygen in the Si bulk as well.     

Facing target sputtered iron-silicide thin film

The FeSi_x thin films with the flatness to an atomic scale for mechanical and optical applications can be grown by a facing target sputtering method. Optical properties indicate the films contain nano-crystalline FeSi₂. The nano-indentation hardness of 10 GPa was obtained. An interesting point is that Young's modulus is larger than that of the carbon-based materials with the same hardness. This means that the FeSi_x is more elastic, which could be characteristic of the chemical bonding of the FeSi₂ with the large contribution of d-electrons. Furthermore, results of the Hall measurement at room temperature shows that the films have p-type conductivity, a carrier concentration of p = 2.49 × 10²⁰ cm^− 3 and a Hall mobility of μ = 6.42 cm² V^− 1 s^− 1.     

Atomic hydrogen emission induced by TEA CO(2) laser bombardment on solid samples at low pressure and its analytical application

Hydrogen emission has been studied in laser plasmas by focusing a TEA CO(2) laser (10.6 microm, 500 mJ, 200 ns) on various types of samples, such as glass, quartz, black plastic sheet, and oil on copper plate sub-target. It was found that H(alpha) emission with a narrow spectral width occurs with high efficiency when the laser plasma is produced in the low-pressure region. On the contrary, the conventional well-known laser-induced breakdown spectroscopy (LIBS), which is usually carried out at atmospheric air pressure, cannot be applied to the analysis of hydrogen as an impurity. By combining low-pressure laser-induced plasma spectroscopy with laser surface cleaning, a preliminary quantitative analysis was made on zircaloy pipe samples intentionally doped with hydrogen. As a result, a good linear relationship was obtained between H(alpha) emission intensity and its concentration.     

Lifelong severe verrucosis associated with human papillomavirus type 2: report of a case with a 38-year follow-up

Sulfite ion (HSO3-) is one of the products when elemental sulfur is oxidized by the hydrogen sulfide:ferric ion oxidoreductase of Thiobacillus ferrooxidans AP19-3. Under the conditions in which HSO3- is accumulated in the cells, the iron oxidase of this bacterium was strongly inhibited by HSO3-. Since cytochrome c oxidase is one of the most important components of the iron oxidase enzyme system in T. ferrooxidans, effects of HSO3- on cytochrome c oxidase activity were studied with the plasma membranes of HSO3(-)-resistant and -sensitive strains of T. ferrooxidans, OK1-50 and AP19-3. The enzyme activity of AP19-3 compared with OK1-50 was strongly inhibited by HSO3-. To investigate the inhibition mechanism of HSO3- in T. ferrooxidans, cytochrome c oxidases were purified from both strains to an electrophoretically homogeneous state. Cytochrome c oxidase activity of a purified OK1-50 enzyme was not inhibited by 5 mM HSO3-. In contrast, the same concentration of HSO3- inhibited the enzyme activity of AP19-3 50%, indicating that the cytochrome c oxidase of OK1-50 was more resistant to HSO3- than that of AP19-3. Cytochrome c oxidases purified from both strains were composed of three subunits. However, the molecular weight of the largest subunit differed between OK1-50 and AP19-3. Apparent molecular weights of the three subunits of cytochrome c oxidases were 53,000, 24,000, and 19,000 for strain AP19-3 and 55,000, 24,000, and 19,000 for strain OK1-50, respectively.