On the kinetics of the chlorination of titanium dioxide in the presence of solid carbon

Metallurgical and Materials Transactions B - The influence of solid carbon on the chlorination of TiO2 with Cl2 and CO-CO2-Cl2 gas mixtures was investigated gravimetrically using rutile and...     

Tyl6, a novel Ty3/gypsy-like retrotransposon in the genome of the dimorphic fungus Yarrowia lipolytica

The novel LTR retrotransposon Tyl6 was detected in the genome of the dimorphic fungus Yarrowia lipolytica. Sequence analysis revealed that this element is related to the well-known Ty3 element of Saccharomyces cerevisiae and, especially, to the recently described Tse3 retrotransposon of Saccharomyces exiguus and to the del1-like plant retrotransposons. Tyl6 is 5108 bp long, is flanked by two identical long terminal repeats (LTR), each of 276 bp, and its ORFs are separated by a -1 frameshift. Both ORFs are intact and deduced translation products display a significant similarity with those of previously described Ty3/gypsy retrotransposons. Distribution of Tyl6 among Y. lipolytica strains of different origins was also analysed. A single copy of the novel retrotransposon is present in some commonly used laboratory strains, which are derivatives of the wild-type isolate YB423-12, whereas other strains of independent origin are devoid of Ty16. No solo LTR of Tyl6 was detected in the analysed strains.     

Alkyl phosphocholines: Toxicity and anticancer properties

The study reports on the investigation of acute and subacute toxicity and on antineoplastic activity of hexadecylphosphocholine (HPC), the first compound of a new class of antineoplastic chemotherapeutics. In rats, the LD₅₀ of HPC was 606 μmol/kg; the maximum tolerable dose over four weeks was 39 μmol/kg. Symptoms of toxicity were enteritis, spider cell activation in the liver, hemosiderosis in the spleen and reversible transaminase increase. The best therapeutic effect was observed on methylnitrosourea (MNU)-induced mammary carcinoma in the rat. Two transplantable mammary carcinomas in the rat and autochthonous benzo(a)pyrene-induced sarcomas exhibited low-grade sensitivity to HPC. The MXT mammary carcinoma of the mouse, the Walker 256 carcinosarcoma of the rat, and autochthonous acetoxymethylmethylnitrosamine-induced colonic tumors of the rat were not chemosensitive to HPC.     

Simulation in der Prozeßleittechnik

Simulation in process control. Distributed control systems provide their users with many potential benefits which are exhaustively used only in a small number of applications. Distributed control systems supply process data in real time in a digital format. When processing these data together with process models, the advantages of distributed control systems can be considerably extended. Process models are understood as mathematical systems containing a-priori knowledge about processes in a numerical or logical form. In the context of distributed control systems, some new and exciting applications of modelling and simulation techniques become accessible. Basic concepts of these specific techniques are described in this contribution. A collection of potential and realized applications show that these methods allow for a more detailed observation and for advanced process control strategies.     

Physical characterisation and chemical composition of densified biomass fuels with regard to their combustion behaviour

With respect to the use of densified biomass fuels in fully automatic heating systems for the residential sector a high quality of these fuels is required. Several European countries already have implemented standards for such fuels. In other countries such standards are in preparation or planned. Furthermore, in some countries also standards from associations are existing (e.g. from the Austrian Pellets Association). In addition to these national standards, European standards for solid biomass fuels are under development. For producers of densified biomass fuels, especially for pellet producers, it is therefore very important to produce high-quality fuels keeping the limiting values of the standards addressed. However, in this context it has to be considered that as a high fuel quality as is necessary for the combustion of densified biomass fuels in automatic small-scale furnaces is not necessary if these fuels are used in larger industrial furnaces as they are equipped with more sophisticated flue gas cleaning, combustion and process control systems. Two pellet qualities, one for industrial and one for small-scale consumers seem to be more meaningful.

Within the framework of the EU-ALTENER-project “An Integrated European Market for Densified Biomass Fuels (INDEBIF)” a questionnaire survey of European producers of densified biomass fuels was performed. In this connection the possibility was offered to the producers to participate in an analysis programme with their fuels. An overview was obtained of the qualities of densified biomass fuels offered in the European market, covering pellets and briquettes from Austria, Italy, Sweden, Spain, Norway and the Czech Republic.

The parameters analysed were the dimensions of the fuels, the bulk and the particle density, the water and the ash content, the gross and the net calorific value, the abrasion, the content of starch (as an indication for the use of biological binding agents), the concentrations of C, H, N, S, Cl, K as well as of the heavy metals Cd, Pb, Zn, Cr, Cu, As and Hg. These parameters have been chosen following the Austrian, German, Swiss and Swedish standards for densified biomass fuels.

The results showed that a majority of the participating producers produce fuels of high quality. However, wood pellets of some producers show a high abrasion, one of the most important quality parameters for pellets. An increased amount of fines often causes failures in the feeding systems used in the residential heating sector. In order to decrease abrasion, the addition of small amounts of biological binding agents (e.g. maize or rye) is possible. This kind of additive is most common in Austria.

Moreover, some producers obviously use not only chemically untreated raw materials or additives, which increase the content of pollutants. Such fuels cause problems regarding emissions, deposit formation and corrosion. Emission problems are expected due to increased contents of N, Cl, S as well as heavy metals. Increased concentrations of heavy metals additionally contaminate the ash, increased Cl concentrations raise the risk of corrosion. Moreover, an increased content of K has a negative effect on the ash melting behaviour and causes higher aerosol formation, which enhances deposit formation and particulate emissions.     

CuGaSe2 solar cells prepared by MOVPE

Metal organic vapor-phase epitaxy (MOVPE) is used to prepare epitaxial reference films and solar cells based on CuGaSe₂. Room temperature Hall measurements are performed on epitaxial CuGaSe₂. Conductivities up to 0.7 (Ω cm)⁻¹ were obtained. Highest mobilities of 270 cm²/Vs are observed for near stoichiometric slightly Ga-rich films. Net charge carrier concentration is higher in the Cu-rich grown films than in the Ga-rich films. Solar cells with epitaxial absorber are prepared that reach efficiencies of 3.3%. First polycrystalline solar cells are grown on Mo/glass at reduced substrate temperatures. Under AM1.5 illumination open-circuit voltages up to 740 mV and efficiencies of 2.0% are obtained.     

Rational Three-Step Method for Optimizing Value of Civil Engineering Research

State DOTs and other agencies and organizations desire to solve difficult practical problems in design, construction, and maintenance of infrastructure. To help accomplish this they request and receive proposals from researchers to solve such problems. An obstacle the agencies face in both writing the research request and in reviewing the proposals is to rationally determine how to obtain the best value for the research funding. This paper proposes a rational means to qualitatively and quantitatively determine relative values using a simple record-keeping matrix and basic tenets of error analysis. Using inferential or other means to estimate uncertainty, and using basic error propagation techniques, research value can be rationally optimized in a three-step method of (1) assembling or requiring an objective-variable matrix; (2) inferring assumptions of variable error based on practical observation; and (3) calculating error propagation through the proposed parametric functions. This methodology will also help with scope management of proposed research and organizing research results.     

Surface Modification of Al2O3/TiC Cutting Ceramics

Cutting ceramics with a graded TiC-rich surface have been obtained by an in situ reaction. Al₂O₃/TiC ceramics, prepared by reaction sintering, have been subjected to various thermal posttreatments at atmospheric pressure. The temperature, dwelling time, and reaction atmosphere have been varied. It has been observed that a TiC-rich surface develops in CO-containing atmospheres. The microstructure of the bulk remains unaffected. Thermal treatment under a CO atmosphere at 1600 ° C for 1 h resulted in a dense TiC layer on the ceramic. A schematic model is proposed for this layer formation process.