Development of a Dosing Concept for Minute Flow Rates

Pressure and volume flow control is a non‐trivial problem in the range of minute molar fluxes. Requirements with regard to precision, stability and flexibility go beyond the specifications of commercially available systems. The present concept offers a functional solution for flexible dosage of norm volume flows down into the μL flow range providing at the same time a suitable pressure control. Furthermore an opportunity for in situ calibration of capillaries concerning their length and inner diameter is introduced. The described setup, after calibration, provides the possibility to determine the unknown viscosity of gaseous mixtures, which are very sparsely found in literature.     

Processing of porous carbon with tunable pore structure by the carbide-derived carbon method

Biomorphic TiC ceramics were covered with highly porous carbon, so-called carbide-derived carbon (CDC), by selective etching of Ti with chlorine in a temperature range between 400° C and 1,200°C. Microporous carbon with narrow pore size distribution was obtained at temperature ranging from 400°C to 800°C. Chlorination at higher temperatures leads to formation of mesopores because of increased degree of order of the obtained CDC. A higher etching rate as well as higher degree of order at lower reaction temperature was observed if a catalytically active metal like Fe or Ru was presented during the chlorination process. This is associated with an increased amount of mesopores and with a decrease in specific surface area. Therefore, the CDC processing in the presence of a catalyst offers another way to produce ordered carbon structures at lower temperatures.     

Eine Studie über den Pyrolysevorgang bei organischen Bindemittelsubstanzen für die Herstellung von Kohlenstoffmaterialien

Pyrolysis behaviour and coke characteristics of different precursors for carbon processing: thermosetting resins (resol, novolak), hydrolytic lignin, pitch, tar as well as their blends were studied using differential thermal analysis (DTA) and X-ray diffraction techniques. The blends novolak-pitch, resol-tar and resol-hydrolytic lignin show a higher coke yield after carbonisation up to 1000°C compared to the corresponding individual substances. A good correlation between the integral procedural decomposition temperature T of the investigated precursors and their coke yield is found.     

Anodic Oxidation of Carbon Fibres in Diammonium Hydrogen Phosphate Solution

Anodic surface treatment of high tensile-carbon fibres under galvanostatic conditions has been performed in diammonium hydrogen phosphate solution, containing an addition of ammonium rhodanide.

The oxidized fibres have been characterized by monofilament tensile strength, XPS measurements and surface energetic analysis. Additionally, the acid-base interactions have been evaluated by wetting with aqueous solutions of different pH values.

An addition of ammonium rhodanide to the diammonium hydrogen phosphate anodization bath affects the oxidation of carbon fibres in terms of decreasing both the amounts of the surface oxides as well as that of degradation by-products. At the optimal treatment conditions (I = 100 mA) no changes in the tensile strength or BET-surface area of the fibre have been observed. The rise in ILSS values of amine cured epoxy composites is not dependent on O_ls/C_ls ratio or surface free energy of the reinforcing fibres, but on the acidic as well as nitrogen functional groups on their surface.     

Chemical vapour deposition of silicon carbide on hollow and C-shaped carbon fibres

The thermally induced chemical vapour deposition of silicon carbide from methyltrichlorosilane (MTS) on isotropic pitch based carbon fibres with hollow and C-shaped cross sections was investigated. The uncoated and coated fibres were characterized by their mechanical properties (tensile strength, Young's modulus and torsional rigidity modulus) and surface energetic analysis. The oxidation behaviour of the carbon fibres before and after coating was discussed in terms of the weight change measured in a thermal balance during heating in an air flow at a constant heating rate.     

Thermal conductivity of porous SiC composite ceramics derived from paper precursor

Biomorphic porous SiC composite ceramics were produced by chemical vapor infiltration and reaction (CVI-R) technique using paper precursor as template. The thermal conductivity of four samples with different composition and microstructure was investigated: (a) C-template, (b) C-SiC, (c) C-SiC–Si₃N₄ and (d) SiC coated with a thin layer of TiO₂. The SiC–Si₃N₄ composite ceramic showed enhanced oxidation resistance compared to single phase SiC. However, a key property for the application of these materials at high temperatures is their thermal conductivity. The later was determined experimentally at defined temperatures in the range 293–373 K with a laser flash apparatus. It was found that the thermal conductivity of the porous ceramic composites increases in the following order: C-template < C-SiC < C-SiC–Si₃N₄ < SiC–TiO₂. The results were interpreted in regard to the porosity and the microstructure of the ceramics.     

A report of an intrathoracic case of hibernoma

The paper describes the synthesis of 6-[4-alkylpiperazinyl-1)phenylamino]-1,2,5-thiadiazolo[3,4-h ]quinolines where methyl (Drug G-1574) and ethyl (Drug G-1569) are alkyls. The two agents are as effective as mebendazole against the larval stage of Echinococcus multilocularis infection. Drug G-1574 has been demonstrated to ensure 100% recovery of spontaneously Hymenolepis nana-infected albino mice given doses 2.5-5 times lower than the effective dose of phenasal (niclosamide).