Ferro-electric pellet shape effect on C/sub 2/F/sub 6/ removal by a packed-bed-type nonthermal plasma reactor

Ceramic dielectric material pellet shape effects on the performance of perfluoroethane (C/sub 2/F/sub 6/) gas removal from simulated semiconductor process gas using packed-bed reactor are experimentally investigated. The bench-scale cylindrical shaped (plasma part: 30-mm inner diameter and 20-mm length) plasma reactor consists of two metal mesh electrodes packed with spherical, cylindrical, or hollow cylindrical shaped ferro-electric pellets with various dielectric constants. The 60-Hz ac high voltage was applied to the mesh electrode. The 3000 ppm C/sub 2/F/sub 6/ gas diluted with nitrogen was used as simulated gas with flow rate of 30 mL/min. The C/sub 2/F/sub 6/ concentration was monitored using Fourier transform Infrared absorption spectroscopy measurements. The results show that the packed-bed plasma reactor with the hollow cylindrical-shaped pellets removed the C/sub 2/F/sub 6/ gas with energy efficiency of 3.7 g/kWh. This value was almost 1.5 times higher than the efficiency 2.5 g/kWh in case of the spherical pellets. The discharge characteristics in the reactor were also changed with the pellet shape. The discharge onset voltage decreases by changing the pellets shape from sphere to hollow cylinder. The quantity of charges accumulated with the microdischarge currents increases by changing the pellet shape from sphere to hollow cylinder in spite of fact that the energy consumed in the reactor decreases.     

Spanwise propagation of turbulence in the plane Couette flow

Propagation of turbulence in the plane Couette flow is analysed based on the Nee-Kovasznay model. The flow state is assumed uniform in the main stream direction, and a turbulent region is assumed to propagate spanwise into the laminar region with a constant speed. The speed is obtained to be 0.08U₀, where the velocity difference between two boundaries is 2U₀. Possible applications of this result are discussed.     

Near‐IR Absorbing Nickel(II) Porphyrinoids Prepared by Regioselective Insertion of Silylenes into Antiaromatic Nickel(II) Norcorrole

The treatment of an antiaromatic norcorrole Ni^II complex with a kinetically stabilized silylene provided ring‐expansion products in excellent yields through the highly regio‐ and stereoselective insertion into the β‐β pyrrolic C? C bonds. The resultant Ni^II porphyrinoid monoinsertion product exhibited relatively strong near‐IR absorption bands due to the small HOMO–LUMO gap in spite of the disrupted cyclic π‐conjugation by the silicon atom.     

Deformation of a tensile membrane adjacent to a moving wall caused by viscous flow

Theoretical analysis is done for deformation of a tensile membrane caused by viscous flow between the membrane and a solid boundary (wafer) placed adjacent to the membrane. The membrane and its support are assumed to have circular shapes. The boundary is assumed to move perpendicularly to the membrane by a small fraction of the gap width. The Hele–Shaw flow theory is applied to the flow. Variation of the central gap width is obtained, and it is shown that the maximum membrane deformation depends on the membrane tension and the final gap width. The dependence agrees with experimental results.     

Effect of zinc salts on the spontaneous copolymerization of 4-vinylpyridine with various electron-rich vinyl monomers

The spontaneous copolymerization of 4-vinylpyridine (4-VP) complexed with three different zinc salts (chloride, acetate, and triflate) with various electron-rich vinyl monomers (p-methoxystyrene, MeOSt; p-methylstyrene, MeSt; α-methylstyrene, α-MeSt; p-tert-butylstyrene, BuSt; styrene, St) was investigated in methanol at 75°C. Increasing the zinc salt concentration or the nucleophilicity of the electron-rich monomer increased the copolymer yields. All obtained copolymers are characterized by high molecular weight (10⁵) and broad molecular weight distribution. Both ¹H-NMR and elemental analyses confirmed the almost 1 : 1 copolymer structure. Changing the anion of the zinc salt does not have a considerable effect either on the copolymerization rate or on the molecular weight. The proposed mechanism exhibits the formation of a σ-bond between the β-carbons of the two donor–acceptor monomers. This creates the 1,4-tetramethylene biradical intermediate which can initiate the copolymerization reaction. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2787–2792, 1997     

Solution properties of celluloses from different biological origins in LiCl · DMAc

Differences in the solution properties of cellulose in 8%LiCl·DMAc (dimethyl acetamide) were investigated usingcelluloses from different origins. The latter included plants (dissolving pulp(DP), cotton linters (CC), and kraft pulp), bacteria (Acetobacterxylinum, BC), and marine animals (tunicin fromHalocynthia). The celluloses from plants and bacteriaformed LiCl·DMAc solutions that were isotropic andanisotropic, respectively; and the animal cellulose was insoluble. The weightaverage molecular weights, M_w, of DP, CC and BC were found to be98.2×10⁴,170×10⁴ and192×10⁴, respectively. The solutionviscositieswere proportional to c (c; polymer concentration) in thedilute and semi-dilute regions, where the exponent was 1 for allsamplesin the dilute region; in the semi-dilute region, it was 4 for the DP and CCsolutions and 3 for the BC solution. Molecular weight differences werecompensated by plotting the viscosity against cM_w orc[] (where [] is the limiting viscosity number).The difference in viscosity behavior at elevated solutionconcentration indicates that the cellulose molecules from DP and CC behave asflexible polymer chains and those of BC as rod-like ones.These results suggest that differences in molecular structure andproperties exist between celluloses from different sources, and that thesedifferences relate to the mechanism or the type of the intermolecularinteraction between the celluloses of plants (DP and CC) and those of bacteria(BC).     

Pulsed Power Applications for Protein Conformational Change and the Permeabilization of Agricultural Products

Pulsed electric fields (PEFs), which are generated by pulsed power technologies, are being tested for their applicability in food processing through protein conformational change and the poration of cell membranes. In this article, enzyme activity change and the permeabilization of agricultural products using pulsed power technologies are reviewed as novel, nonthermal food processes. Compact pulsed power systems have been developed with repetitive operation and moderate output power for application in food processing. Firstly, the compact pulsed power systems for the enzyme activity change and permeabilization are outlined. Exposure to electric fields affects hydrogen bonds in the secondary and tertiary structures of proteins; as a result, the protein conformation is induced to be changed. The conformational change induces an activity change in enzymes such as α-amylase and peroxidase. Secondly, the conformational change in proteins and the induced protein functional change are reviewed. The permeabilization of agricultural products is caused through the poration of cell membranes by applying PEFs produced by pulsed discharges. The permeabilization of cell membranes can be used for the extraction of nutrients and health-promoting agents such as polyphenols and vitamins. The electrical poration can also be used as a pre-treatment for food drying and blanching processes. Finally, the permeabilization of cell membranes and its applications in food processing are reviewed.