Search results for "Heterogeneou"
showing 10 items of 461 documents
Radio environment map estimation based on communication cost modeling for heterogeneous networks
2017
Los mapas del entorno radioeléctrico pueden ser una poderosa herramienta para lograr una asignación de recursos eficiente y consciente del contexto en las redes heterogéneas 5G. En este trabajo, consideramos una red heterogénea formada por una red celular tradicional y una red de sensores inalámbricos. El papel de la red de sensores inalámbricos es estimar el mapa del entorno radioeléctrico de la célula utilizando una técnica de interpolación geoestadística denominada Kriging. En un trabajo anterior se propuso un algoritmo de agrupación distribuida de sensores para reducir la complejidad de la estimación. En nuestra contribución, el proceso de formación de clústeres se modifica para incluir…
Stabilized Naked Sub-nanometric Cu Clusters within a Polymeric Film Catalyze C-N, C-C, C-O, C-S, and C-P Bond-Forming Reactions
2015
[EN] Sub-nanometric Cu clusters formed by endogenous reduction of Cu salts and Cu nanoparticles are active and selective catalysts for C−N, C−C, C−O, C−S, and C−P bond-forming reactions. Sub-nanometric Cu clusters have also been generated within a polymeric film and stored with full stability for months. In this way, they are ready to be used on demand and maintain high activity (TONs up to 104 ) and selectivity for the above reactions. A potential mechanism for the formation of the sub-nanometric clusters and their electronic nature is presented.
Thrombin-antithrombin III complexes in type II diabetes mellitus.
1992
Several studies suggest that diabetes is associated with a hypercoagulable state. Therefore determination of thrombin-antithrombin complex (TAT) could represent a sensitive parameter for specific detection of a latent activation of the clotting system. The present study documents increased plasma TAT in a heterogeneous group of non-insulin-dependent diabetic patients. The finding of increased TAT levels both in diabetic patients with vascular complications and in vascular disease patients without diabetes suggests a relationship between existing vascular disease and the hemostatic mechanism that produces augmented thrombin activity. In acute vascular occlusions the presence of diabetes seem…
High-density electromyography activity in various hamstring exercises
2019
Proximal-distal differences in muscle activity are rarely considered when defining the activity level of hamstring muscles. The aim of this study was to determine the inter-muscular and proximal-distal electromyography (EMG) activity patterns of hamstring muscles during common hamstring exercises. Nineteen amateur athletes without a history of hamstring injury performed 9 exercises, while EMG activity was recorded along the biceps femoris long head (BFlh) and semitendinosus (ST) muscles using 15-channel high-density electromyography (HD-EMG) electrodes. EMG activity levels normalized to those of a maximal voluntary isometric contraction (%MVIC) were determined for the eccentric and concentr…
Human cooperation in groups: variation begets variation
2015
Open Access Published: 04 November 2015 Human cooperation in groups: variation begets variation Pieter van den Berg, Lucas Molleman, Jaakko Junikka, Mikael Puurtinen & Franz J. Weissing Scientific Reports volume 5, Article number: 16144 (2015) Cite this article 383 Accesses 4 Citations 6 Altmetric Metricsdetails Abstract Many experiments on human cooperation have revealed that individuals differ systematically in their tendency to cooperate with others. It has also been shown that individuals condition their behaviour on the overall cooperation level of their peers. Yet, little is known about how individuals respond to heterogeneity in cooperativeness in their neighbourhood. Here, we presen…
Mo–V–Nb mixed oxides as catalysts in the selective oxidation of ethane
2003
Abstract Mo–V–Nb–O mixed metal oxides, obtained by heat-treatment in N 2 at 425 °C, have been studied as catalysts in the oxidative dehydrogenation of ethane. They present higher catalytic activity, while maintaining the same selectivity to ethylene, than the corresponding metal oxides calcined under air. Both amorphous and crystalline phases are present on active and selective catalysts. The implications of the presence of these phases as well as their physicochemical characteristics on the nature of active and selective sites are discussed.
Deep oxidation of volatile organic compounds using ordered cobalt oxides prepared by a nanocasting route
2010
Ordered Co3O4 with high surface area (until 173 m2/g) has been successfully obtained through a nanocasting route using mesoporous KIT-6 silica as a hard template and tested in the deep oxidation of a series of representative volatile organic compounds (VOCs): propane as a model of short chain alkane and toluene as a model of monoaromatic hydrocarbon. It has been demonstrated that the catalytic activity for VOC deep oxidation is very elevated and its catalytic stability at moderate temperatures very good. However, the role of the ordered structure in the catalytic performance does not seem to be beneficial. The enhanced catalytic activity has been explained in terms of both the high surface …
Improved (photo)catalytic propene hydration in a gas/solid system by using heteropolyacid/oxide composites: Electron paramagnetic resonance, acidity,…
2017
Binary materials composed of the oxides SiO2, TiO2 and N-doped TiO2 and the Keggin heteropolyacid (PW12) were prepared and physicochemically characterized. They were used as catalysts and photocatalysts for the hydration of propene to 2-propanol. The characterization of the samples, particularly the electron paramagnetic resonance (EPR) spectroscopy results and the acidity properties, were useful to explain the key role played by the PW12 in the composite materials in the thermal and photoassisted catalytic processes. The simultaneous pres-ence of heat and UV light improved the activity of PW12 in the thermal process, and the binary materials showed better (photo)catalytic activities than t…
A Green Look at the Aldol Reaction
2005
Aldol reactions have been and are widely applied for the preparation of β-hydroxy aldehydes, β-hydroxy ketones or α,β-unsaturated aldehydes or ketones through addition or addition-elimination reactions of aldehydes and ketones. The study of the aldol reaction from the point of view of its greenness must have in mind first of all that a general synthetic method must be based on complete and efficient conversions of well defined selectivity and that greenness is more a term for comparison than an absolute kind of qualification. This comparison, when referred to the aldol reaction, applies here to the diverse modifications of the reaction. Thus, the original poorly selective, but highly atom e…
Ammonia Synthesis: State of the Bellwether Reaction
2013
Catalytic ammonia synthesis has been judged to be one of mankind's greatest scientific achievements during the twentieth century. The socioeconomic implications of producing ammonia industrially have been a strong driving force, and this development has spurred a range of new discoveries within physics, chemistry, and chemical engineering. In this chapter, we describe how it has been possible in recent years to provide a full understanding of the catalytic ammonia synthesis reaction at the atomic level through the combined use of experiments and quantum mechanical electronic structure calculations, thus clearly showing many of the reasons why ammonia synthesis has been, and still is, the be…