243 research outputs found
On the Limited Role of Electronic Support Effects in Selective Alkyne Hydrogenation: A Kinetic Study of Au/MO\u3csub\u3ex\u3c/sub\u3e Catalysts Prepared from Oleylamine-Capped Colloidal Nanoparticles
We report a quantitative kinetic evaluation and study of support effects for partial alkyne hydrogenation using oleylaminecapped Au colloids as catalyst precursors. The amine capping agents can be removed under reducing conditions, generating supported Au nanoparticles of ~2.5 nm in diameter. The catalysts showed high alkene selectivity (\u3e90%) at all conversions during alkyne partial hydrogenation. Catalytic activity, observed rate constants, and apparent activation energies (25â 40 kJ/mol) were similar for all Au catalysts, indicating support effects are relatively small. Alkyne adsorption, probed with FTIR and DFT, showed adsorption on the support was associated with hydrogen-bonding interactions. DFT calculations indicate strong alkyne adsorption on Au sites, with the strongest adsorption sites at the metal-support interface (MSI). The catalysts had similar hydrogen reaction orders (0.7â0.9), and 1- octyne reaction orders (~ 0.2), suggesting a common mechanism. The reaction kinetics are most consistent with a mechanism involving the non-competitive activated adsorption of H2 on an alkyne-covered Au surface
Photochemical efficiency of photosystem in Carapichea ipecacuanha under shading in different seasons of the year.
Germination of chapolinÂź tomato using different substrates and shading.
Vegetable production is a great source of Brazilian income and has been widely studied. Thus, the formation of substrates that promote better seedling cultivation conditions and the amount of light received become important research factors for better results in the final product. The use of coconut fiber (FC) has been widely used in the production of seedlings of many vegetable species. Thus, the objective of this work was to evaluate the interaction of different substrate compositions and different shading levels in the germination of tomato of the ChapolinÂź variety. For this, the experiment was conducted at three different shading levels (70 and 90%) and 5 different mixtures of substrates with different concentrations of clay (A) and coconut fiber (FC): T1 (100% A), T2 (80 % A + 20% FC), T3 (60% A + 40% FC), T4 (40% A + 60% FC) and T5 (100% FC), in a completely randomized design, with four replications for each level of shading and substrate concentration. The beginning of germination occurred on the seventh day after sowing (DAS) and lasted until the fourteenth DAS. The type of substrate concentration with the highest germination percentage was the T2 substrate and the shading was 70%. Thus, for such experimental conditions, the concentration of 80% clay with 20% coconut fiber is indicated, when conducted in 70% shading and for 90% shading conditions, the composition of 60% clay and 40% fiber of coconut
Die Bedeutung der Neurobiologie fĂŒr die Kinder- und Jugendlichentherapie
Welche Bedeutung haben die in den letzten beiden Jahrzehnten erarbeiteten neurobiologischen Forschungsergebnisse fĂŒr die Praxis der Kinder- und Jugendlichentherapie? Das ist die Frage, mit der ich mich im Folgenden beschĂ€ft igen möchte. Ich selber schwanke immer zwischen zwei Extremen: Einerseits fi nde ich es faszinierend, ĂŒber neuere neurobiologische Erkenntnisse zu lesen und ihre Bedeutung fĂŒr die Psychotherapie mit Kindern und Jugendlichen zu refl ektieren. Andererseits habe ich oft den Eindruck, dass die zweifellos beeindruckenden Forschungsmethoden doch nur sehr eingeschrĂ€nkt in der Lage sind, etwas von der KomplexitĂ€t der VorgĂ€nge im Gehirn zu erfassen. Sie fordern die Forscher damit zu Interpretationen heraus mit der Folge, dass manche von ihnen darin genau das entdecken, wovon sie vorher ĂŒberzeugt waren. Sicherlich kommen umfangreiche neurobiologische Forschungen in vielen FĂ€llen auch zu Ergebnissen, die aufgrund des inzwischen doch sehr groĂen psychotherapeutischen Erfahrungsschatzes ziemlich selbstverstĂ€ndlich, sozusagen als alte HĂŒte wirken. Das mindert mein persönliches Interesse allerdings nicht. Denn nach meiner Erfahrung ist es oft sehr bereichernd, auch alte HĂŒte mal von einer anderen Seite und unter anderen Aspekten zu betrachten. Und ich erlebe es als sehr spannend zu beobachten, welche Teile dieses therapeutischen Erfahrungsschatzes sich nicht bestĂ€tigen werden
Effects of malt bagasse utilization on kale germination using different substrates and shadings.
Malt bagasse is an important waste from breweries, with high potential of usage in various animal and human food areas. Nonetheless, there are few studies of its in natura usage as soil conditioner for various vegetables seedings production. Thus, this works objective was evaluate the interaction among different substrate compositions, using brewery waste as component, and different shading levels at Georgian cabbage germination. For that, the experiment was made in five different shading levels (50%, 70%, 90%, 70% with plastic and full sun) and three different substrates moistures with distinct compositions: S1 (33,33% of manure; 33,33% of sandy soil; 33,33% of clayish soil), S2 (83% of earthworm humus; 15% of fine glyceride charcoal; 2% of mammon dumpling), S3 (33,33% of brew waste; 33,33% of sandy soil; 33,33% of clayish soil), in an completely randomized design, with five repetitions for each shading level and substrate concentration. Germination beginning occurred in the third day after sowing (DAS) and lasted until the tenth DAS. The S2 substrate stood out, followed by S1, with similar results in height, roots length, germination percentage, and germination speed index. On the other hand, the substrate composed of malt bagasse obtained the worst results in all shading conditions, being not indicated to kale seedings production
Avaliação sazonal da produção de emetina e cefalina em raĂzes de Carapichea ipecacuanha (Rubiaceae): uma espĂ©cie em erosĂŁo genĂ©tica.
The political economy of high skills:Higher Education in knowledge-based labour markets
<p>A successful transition into the knowledge economy depends upon higher level skills, creating unprecedented pressure on university systems to provide labour markets with the skills needed. But what are the political economy dynamics underlying national patterns of high skill formation? The article proposes a framework to theorize the relationship between higher education systems and knowledge-based labour markets based on two dimensions: the type of knowledge economy predominant in a given country and the extent of inter-university competition. It is argued that the former explains what type of higher level skills will be sought by employers and cultivated by governments, while the latter helps us understanding why some higher education systems are more open to satisfying labour market demands compared to others. A set of diverse country case studies (Britain, Germany, South Korea and the Netherlands) is employed to illustrate the theory.</p
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