64,124 research outputs found
Opius (Opius) paraplasticus FISCHER 1972
No full textOpius (Opius) paraplasticus FISCHER 1972 M a t e r i a l: Semnan province: Damghan, 1, 1, November 2003. D i s t r i b u t i o n o u t s i d e I r a n: Central Palaearctic, Afrotropical (South Africa).Published as part of Ghahari, H., Fischer, M., K. J, O. C & Beyarslan, A., 2010, Some New records of Braconidae (Hymenoptera) for Iran, pp. 1395-1404 in Linzer biologische Beiträge 42 (2) on page 1400, DOI: 10.5281/zenodo.532390
Opius (Opiothorax) nigricoloratus FISCHER 1958
No full textOpius (Opiothorax) nigricoloratus FISCHER 1958 M a t e r i a l: Semnan province: Shahrood, 1, 1, November 2003. D i s t r i b u t i o n o u t s i d e I r a n: Palaearctic (Austria, Denmark, Finland, Germany, Greece, Hungary, Italy, Mongolia, Spain, Switzerland).Published as part of Ghahari, H., Fischer, M., K. J, O. C & Beyarslan, A., 2010, Some New records of Braconidae (Hymenoptera) for Iran, pp. 1395-1404 in Linzer biologische Beiträge 42 (2) on page 1400, DOI: 10.5281/zenodo.532390
Vanadia Promoted Co-AI20 3 Fischer-Tropsch Catalysts
No full textBibliography: leaves 117-124.The primary aim of this work was to study systematically V20 5 promotion on yAI203 supported cobalt-based Fischer-Tropsch catalysts. The y-Ah03 support was modified by addition of varying amounts of vanadia and was subsequently loaded with the same Co content (10 wt-%). The modified supports and catalysts were characterised using conventional characterisation methods. The physio-chemical properties of the vanadia promoted supports and catalysts were characterised using Atomic Adsorption Spectroscopy (AAS), zeta-potential measurements, and BET measurements, X-ray Diffraction (XRD), Temperature Programmed Reduction (TPR), Transmission Electron Microscopy (TEM), and CO chemisorption. Catalyst performance in the Fischer-Tropsch synthesis was tested in fixed bed reactor. A catalysts synthesised from plain y-A1203 was used as a base catalyst. Characterization results show that modification of y-Ab03 support to obtain V205 loadings beyond 1-monolayer vanadia coverage was difficult when using ion exchange. Ion-exchange equilibrium limitations might have caused the poor vanadia loadings beyond 1-monolayer coverage. The supports net surface charge as measured using zeta potential, was decreased by vanadia content in the supports. CO chemisorption results were complex and could only be modelled using dual site Langmuir model assuming the presence of two different sites absorbing CO on the Co-V-AI catalyst system. This made extraction of physical properties from this method rather difficult. Fischer Tropsch synthesis reaction was carried out at typical industrial conditions (T=220°C, P=20 bar (a), H2/CO=2 Xco-60 mol-%) for cobalt catalysts. Vanadia promoted catalysts showed a marked decrease in initial activity. However, the overall deactivation rate was lower with increasing vanadia content. The vanadia content did not affect the chain growth kinetic behavior of the catalyst in the Fischer-Tropsch synthesis hence C5+ selectivity in the Fischer-Tropsch synthesis was unperturbed by vanadia content. Increasing the vanadia content in the catalyst resulted in high n-olefin content and high 1-olefin content. The observed increase in olefin content might be due to the low catalytic activity observed for the catalysts with high vanadia loadings. The most pronounced effect of vanadia promotion on Fischer Tropsch synthesis was in the oxygenate content in the Fischer-Tropsch product. Catalysts with high vanadia loading yielded high amounts of oxygenate products; mainly alcohols and aldehydes
Beckel (L.), Fischer (H.), Julg (F.), Scheidl (K.). — Luftbildatlas Oesterreich (Atlas autrichien de photos aériennes).
No full textLoup Jean. Beckel (L.), Fischer (H.), Julg (F.), Scheidl (K.). — Luftbildatlas Oesterreich (Atlas autrichien de photos aériennes). . In: Revue de géographie alpine, tome 60, n°2, 1972. p. 404
Beckel (L.), Fischer (H.), Julg (F.), Scheidl (K.). — Luftbildatlas Oesterreich (Atlas autrichien de photos aériennes).
No full textLoup Jean. Beckel (L.), Fischer (H.), Julg (F.), Scheidl (K.). — Luftbildatlas Oesterreich (Atlas autrichien de photos aériennes). . In: Revue de géographie alpine, tome 60, n°2, 1972. p. 404
Modeling Fischer Tropsch synthesis in two-phase, continuous, well-mixed slurry reactors
No full textIncludes abstract.Includes bibliographical references (p. 84-87).Fischer Tropsch Synthesis (FTS) is the conversion of syngas (CO and H2) to cleaner liquid transportation fuels. The modelling of such a supercritical, highly non-ideal, multi-component system requires the detailed knowledge of the reaction mechanism, reaction kinetics, phase-equilibrium and reactor technology. The objectives of this work were to: develop a complete Fischer Tropsch model, predict the hydrocarbon product distribution, determine what effect Vapour-Liquid Equilibrium (VLE) has on the product distribution, selectivity and kinetics, and determine whether the deviations from the 'ideal' Anderson-Schulz Flory (ASF) distribution can be attributed to VLE
Influence of basicity in Fischer-Tropsch synthesis over supported iron-based catalysts
No full textIncludes bibliographical references (leaves 115-124).The Fischer-Tropsch synthesis catalyzed by iron is a well-established process for the production of synthetic fuels, waxes and high-value chemicals, such as α-olefins. A draw-back of the currently used iron-based catalysts is their short lifetime, caused by sintering and particle break-up. These disadvantages might be overcome by utilizing a supported iron-based catalyst. However, supported iron Fischer-Tropsch synthesis, which has been tested up to now, show a high methane selectivity. This might be caused by a lack of alkali near the catalytic site, which can be alleviated by using a basic support. Classical basic supports such as CaO and MgO will react with CO2 (a major by-product in iron-catalyzed Fischer-Tropsch synthesis) yielding carbonates and can therefore not be used, since the formation of carbonates will result in a large particle expansion. An alternative would be to generate a silica-based basic support by attaching basic groups to the silica. In this study iron Fischer-Tropsch catalysts supported on silica were tested for conversion of synthesis gas to hydrocarbon products. Silica was modified with aminopropyltriethoxysilane (APTeS) by impregnation followed by calcination to provide basic surface groups onto the silica surface. The CHN analysis and IR-analysis indicate the presence of amine groups in the APTeS-modified silica. The pore radius distribution of silica is slightly shifted towards higher pore radii in comparison to APTeS-modified silica. It might thus be stated that aminopropyltriethoxysilane covers the pore walls and does not seem to result in pore blockage. Thermal gravimetric analysis indicates that the thermal stability of APTeS-modified silica is low. A major difference between silica and APTeS-modified silica was their zeta-potential. Whereas the surface of silica is mainly negatively charged in the pH-range of interest during impregnation, the surface of APTeS-modified silica is mainly positively charged. This is attributed to the presence of amine groups on the surface. Iron was brought onto the support by impregnation. The surface modification of silica with APTeS seems to be destroyed upon calcination of the impregnated catalysts. The iron phase in the calcined iron catalyst supported on silica catalysts is mainly hematite (Fe203), whereas the iron phase in the calcined iron catalyst supported on APTeS-modified silica catalysts is mainly iron oxide hydroxide FeOOH. The presence of basic amine groups may favour the formation of FeOOH crystallites during the impregnation/calcination on the APTeS-modified silica. The FeOOH-crystallites on the APTeS-modified silica support are typically smaller than the Fe203 crystallites on silica. The maximum catalytic activity is obtained at 0.01 mol K I mol Fe for the iron catalyst supported on silica and at 0.02 mol K I mol Fe for the APTeS-modified catalyst, indicating the optimum potassium loading. The difference in the optimum potassium loading might be linked to the smaller crystallite sizes obtained with the APTeS-modified catalyst. All the potassium promoted catalysts show a lower methane selectivity compared to the 0 K iron catalyst supported on silica and the 0 K iron catalyst supported on APTeS-modified silica. The 1-olefin and n-olefin content in the fraction of linear hydrocarbons increase with increasing potassium loading over all the iron catalyst supported on silica promoted with potassium except for the catalysts 0.005 K and 0.01 K. Increasing potassium content on the catalyst resulted in higher 1-olefin content in the fraction of linear olefins. The trend suggests that potassium promotion suppresses secondary double bond isomerisation of 1-0lefin into internal olefins. The high degree of branching obtained with the 0.005 K catalyst and the 0.01 K catalyst, is characteristic of weak alkali promotion. The iron catalysts supported on APTeS-modified silica indicate an increase in the degree of branching with increasing potassium content
The L-distribution and skew generalizations
No full textLeptokurtic or platykurtic distributions can, for example, be generated by applying certain non-linear transformations to a Gaussian random variable. Within this work we focus on the class of so-called power transformations which are determined by their generator function. Examples are the H-transformation of Tukey (1960), the J-transformation of Fischer and Klein (2004) and the L-transformation which is derived from Johnson's inverse hyperbolic sine transformation. It is shown that generator functions themselves which meet certain requirements can be used to construct both probability densities and cumulative distribution functions. For the J-transformation, we recover the logistic distribution. Using the L-transformation, a new class of densities is derived, discussed and generalized. --Power kurtosis transformation,leptokurtosis,(skew) L-distribution
The L-distribution and skew generalizations
No full textLeptokurtic or platykurtic distributions can, for example, be generated by applying certain non-linear transformations to a Gaussian random variable. Within this work we focus on the class of so-called power transformations which are determined by their generator function. Examples are the H-transformation of Tukey (1960), the J-transformation of Fischer and Klein (2004) and the L-transformation which is derived from Johnson's inverse hyperbolic sine transformation. It is shown that generator functions themselves which meet certain requirements can be used to construct both probability densities and cumulative distribution functions. For the J-transformation, we recover the logistic distribution. Using the L-transformation, a new class of densities is derived, discussed and generalized. --Power kurtosis transformation,leptokurtosis,(skew) L-distribution
cDNA sequence of a protein kinase from the inducible crassulacean acid metabolism plant Mesembryanthemum crystallinum L., encoding a SNF-1 homolog
No full textBaur B, Fischer K, Winter K, Dietz K-J. cDNA sequence of a protein kinase from the inducible crassulacean acid metabolism plant Mesembryanthemum crystallinum L., encoding a SNF-1 homolog. Plant Physiol. 1994;106:1225-1226
- …
