11,681 research outputs found
Rhacalysia congoensis FISCHER 1993
No full textRhacalysia congoensis FISCHER, 1993 Rhacalysia congoensis n.sp.: FISCHER 1993c: 605 (description ♀ ♁, Brazzaville), 639 (figs 23-30). Rhacalysia congoensis FISCHER, 1993: FISCHER 1994: 788 (key). Rhacalysia congoensis FISCHER, 1993: FISCHER 1999: 6 (key). D i s t r i b u t i o n: Brazzaville. Rhacalysia congoensis is recorded only from the Republic of the Congo.Published as part of Madl, Michael, 2022, A catalogue of the Braconidae (Hymenoptera, Ichneumonoidea) of the Republic of the Congo, pp. 235-241 in Linzer biologische Beiträge 54 (1) on page 236, DOI: 10.5281/zenodo.750739
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
Carbidization and size effects of unsupported nanosized iron in the low temperature Fischer-Tropsch process
No full textIncludes abstract.Includes bibliographical references.In the process of developing the most efficient production of fuels from coal or natural gas, there have been major advances in the development of the catalysts used. Previous work at the Centre for Catalysis Research, at the University of Cape Town, has shown great potential and provided a much deeper under- standing of the workings of the Fischer-Tropsch catalyst. The research has found that the catalyst crystallite size plays a crucial part in the product selectivity and requires strict control in order to obtain a certain desired product spectrum. The aim of this project is to provide insight on the behavior of various iron oxide crystallite sizes when placed in a CO concentrated environment during catalyst pretreatment. It will also clarify whether the sizes of the nano-crystallites will increase or decrease when the different phases form and which size carbides faster
[Stammbuch Johann Adrian Fischer] / Johann Adrian Fischer
No full text[STAMMBUCH JOHANN ADRIAN FISCHER] / JOHANN ADRIAN FISCHER
[Stammbuch Johann Adrian Fischer] / Johann Adrian Fischer ( - )
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Carl August; Blatt 6 (5v 6r)
Murrai von Tullibardine, Wilhelm; Blatt 8 (7v 8r)
Brandenstein, Hanß Ernst von; Blatt 14 (13v 14r)
Outenhoorn, N. van; Blatt 21 (20v 21r)
Schenck, Friedrich Ernst; Blatt 23 (23)
Seifried, Johann Christian; Blatt 25 (24v 25r)
Huswedel, Joachim Bernhard; Blatt 26 (25v 26r)
Tanner, Christoph Andreas von; Blatt 27 (26v 27r)
Rebondy, Friedrich Ernst von; Blatt 53 (52v 53r)
Oliver, George; Blatt 57 (56v 57r)
Bering, Christian Ludwig Wilhelm von; Blatt 60 (59v 60r)
Felbinger, Johann Leonhardt; Blatt 63 (62v 63r)
Krebs, Johann Friedrich; Blatt 75 (74v 75r)
Höfer, Georg Friedrich; Blatt 94 (93v 94r)
Wülfer, Johann; Blatt 123 (122v 123r)
Herel, Johann Friedrich; Blatt 128 (127v 128r)
Bremel, Johann Theodorus; Blatt 130 (129v 130r)
Schubart, Johann; Blatt 133 (133)
Kleemann, Nikolaus Moritz; Blatt 134 (133v 134r)
Bodin, Christoph; Blatt 136 (135v 136r)
Reinhard, Georg Michael; Blatt 138 (137v 138r)
Philipp, Franciscus Lotharius; Blatt 140 (139v 140r)
Wack, Johann Conrad; Blatt 141 (140v 141r)
Schulin, Ernst Georg; Blatt 146 (145v 146r)
Wolf, August; Blatt 151 (150v 151r)
Dietzsch, Georg Friedrich; Blatt 152r (151v 152r)
Hack, Georg; Blatt 152v (152v 153r)
Schmid, Johann Gottfried; Blatt 153 (152v 153r)
Kleemann, Georg Paul; Blatt 154v (154v 155r)
Chapuset, Johann Karl; Blatt 155 (154v 155r)
Schenck, David; Blatt 156v (155v 157r)
Kern, G. F.; Blatt 158 (157v 158r)
Sartorius, Johann Christian; Blatt 159 (158v 159r)
Wiprecht, Friedrich Constantin; Blatt 164 (163v 164r)
Hackspan, Christoph Balthasar; Blatt 169 (168v 169r)
Mulner, Johann Joseph; Blatt 170r (169v 170r)
Scharmann, Johann Leonhard; Blatt 170v (170v 171r)
Fleischmann, Anton; Blatt 171 (170v 171r)
Bauriedel, Stephan; Blatt 172 (171v 172r)
Wagner, J. P.; Blatt 176 (176)
Rudolph, Johann Friedrich; Blatt 178 (177v 178r)
Seifried, Johann Christoph; Blatt 179 (178v 179r)
Poschel, Joseph Heinrich; Blatt 180v (180v 181r)
Seifried, Wilhelm Ulrich; Blatt 181v (181v 182r)
Specht, Adrian; Blatt 182v (182v 183r)
Munz, Georg Christoph; Blatt 183 (182v 183r)
Beck, Johann Thomas; Blatt 184r (183v 184r)
Wurffbain, Johann Tobias; Blatt 184v (184v 185r)
Maier, Johann Georg; Blatt 185r (184v 185r)
Müller, Johannes; Blatt 185v (185v 186r)
Eckebrecht, Hieronymus; Blatt 186r (185v 186r)
Gabler, Christoph; Blatt 186v (186v 187r)
Rothschütz, F. W. von; Blatt 187 (186v 187r)
Unbekannt; Blatt 188v (188v 189r)
Ercklin, A.; Blatt 189 (188v 189r)
Baum, Johann Heinrich; Blatt 190r (189v 190r)
Schlözer, Johann Achatius; Blatt 190v (190v 192r)
J. D. G.; Blatt 192 (190v 192r)
Hahn, M. B.; Blatt 194 (192v 194r)
Mohr, L. A.; Blatt 195 (194v 195r)
Jäger, Michael; Blatt 198 (196v 198r)
Illustration (Federzeichnung auf Pergamentblatt): Zwei Herren u. eine Dame weintrinkend unter einem Baum (198v 199r)
Hahn, Johann Georg; Blatt 200 (199v 200r)
Weidner, Erasmus Josias; Blatt 201r (200v 201r)
Göbel, Johann Bernhard; Blatt 201v (201v 203r)
Hanauer, Daniel; Blatt 203r (201v 203r)
Hoffmann, Johann Albert Paul; Blatt 203v (203v 204r)
Obermeyer, L. C. D.; Blatt 204 (203v 204r)
Taubermann, Johann Michael; Blatt 205 (204v 205r)
Fricke, Johann Georg; Blatt 206 (205v 206r)
Meelführer, Johann Wilhelm; Blatt 208 (206v 208r)
Saueracker, Johann Albrecht; Blatt 209 (208v 209r
Do inflation targeters outperform non-targeters?
No full textTen years of empirical studies of inflation targeting have not uncovered clear evidence that monetary policy that incorporates formal targets imparts better inflation performance. The authors survey the literature and find that the "no difference" verdict concerning inflation targeting has been robust to a wide range of countries and methods of analysis, starting with a study by Dueker and Fischer (1996a). The authors present updated Markov-switching estimates from the original Dueker and Fischer (1996a) article and show that their early conclusions about inflation targeting among early adopters have not been overturned with an additional decade of data. These findings to date do not rule out the possibility, however, that formal inflation targets could prove pivotal if the global environment of disinflation were to reverse course.Inflation (Finance)
An efficient three-step synthesis of cyclopenta[b]pyrans via 2-donor-substituted Fischer ethenylcarbenechromium complexes
No full textA wide range of cyclopenta[b]pyrans 4 has been synthesized in a one-pot reaction by treatment of different 2-donorsubstituted ethenylcarbene-chromium complexes 2 with alkynes in THF in moderate to excellent yields (41-90% for 14 out of 25 examples). The starting materials 2 are readily available in good to excellent yields (76-99% for 25 out of 36 examples) by Michael addition of amines, alcohols and thiols, respectively, to the corresponding alkynylcarbenechromium complexes 1. Due to their 10 pi-electrons in a cross-conjugated bicyclic system, cyclopenta[b]pyrans have been termed pseudoazulenes, as they indeed have similar UV/Vis-spectroscopic properties
A guide to nominal feedback rules and their use for monetary policy
No full textIf price stability is to be sustained, monetary policy actions will inevitably resemble - in the long run - the prescriptions from nominal feedback rules, which are designed to achieve price stability. This property means that monetary policy might be well described by a nominal feedback rule in a low-inflation country such as Switzerland. In this article, Michael J. Dueker an Andreas M. Fischer provide a general description of nominal feedback rules and use one rule - with time-varying parameters - to model Swiss monetary policy actions. The authors explain how this indicator model can presage a buildup of inflationary pressures before they become obvious through other traditional policy indicators.Monetary policy ; Switzerland
A Basis for feature-oriented modelling in Event-B
No full textFeature-oriented modelling is a well-known approach for Software Product Line (SPL) development. It is a widely used method when developing groups of related software. Due to reuse methods, the development of the software product is quicker, less expensive and of higher quality. However, this approach is not common in formal methods development, which is generally high cost and time consuming, yet crucial in the development of critical systems. We present a method to integrate feature-oriented development with the formal specification language Event-B. Our approach allows the user to map a feature from the feature model to an Event-B component, which contains a formal specification of that feature. We also present some patterns, which assist the user in the modelling of Event-B components. We describe a composition process which consists of the user selecting an instance in the feature model and then constructing this instance in Event-B. While composing, the user may also discharge new composition proof obligations in order to ensure the model is consistent. The model is then constructed using a number of composition rules.<br/
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