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71.
Effect of Particle Size on Monometallic and Bimetallic (Au,Pd)/C
on the Liquid Phase Oxidation of Glycerol 总被引:2,自引:0,他引:2
Nikolaos Dimitratos Jose Antonio Lopez-Sanchez David Lennon Francesca Porta Laura Prati Alberto Villa 《Catalysis Letters》2006,108(3-4):147-153
The influence of metal particle size of monometallic and bimetallic supported catalysts (Au, Pd, Au–Pd)/C was studied using
as a model reaction the liquid phase oxidation of glycerol. By tuning the metal particle size from 2 to 16 nm a progressive
decrease of activity and simultaneously an increase in the selectivity to sodium glycerate was observed. Moreover, the influence
of the temperature was studied and it was found that by increasing the temperature, only with a large particle size the formed
glycerate was retained and not over-oxidized to tartronate. 相似文献
72.
The Steady radial distribution of chemical species in a wire‐to‐cylinder ozone generator filled with pure oxygen has been computed by applying four different plasma chemistry models of increasing complexity. The most complete model considers ten species (e, O2 +, O2 ?, O3 ?, O?, O2, O2(1Δg), O2(1∑g +), O and O3) and 79 reactions, including ionization by electron impact, electron attachment and detachment, electron-ion recombination, charge transfer, etc. The chemical model is coupled with the electrical model through Poisson's equation. The spatially averaged ozone density has been computed as a function of the current intensity and compared with the experimental values obtained by UV spectroscopy. 相似文献
73.
Jose Ivan Escalante-Garcia Victor M. Palacios-Villanueva Alexander V. Gorokhovsky Guillermo Mendoza-Suárez Antonio F. Fuentes 《Journal of the American Ceramic Society》2002,85(7):1788-1792
Mortars of blast furnace slag blended with a geothermal silica waste at various replacement levels of 0%, 5%, 10%, 15%, and 20% were cured for up to 90 days. The binder was activated by 6 wt% Na2 O equivalent of sodium hydroxide. Lime was added as an activating agent and also to promote pozzolanic reaction with the silica. It was found that the presence of the silica waste increased the reactivity of the cementitious materials, as measured by means of nonevaporable water. The compressive strength was increased in the presence of the silica, except at the highest replacement level of 20%, the optimum silica replacement was that of 5%–10%. The microstructures of blended slag showed less porosity than those of neat slag mortars. The lime was completely consumed after 90 days of hydration. 相似文献
74.
Gregorio Martinez Perez Antonio F. Gomez Skarmeta Steve Zeber Joe Spagnolo Tim Symchych 《Communications Magazine, IEEE》2006,44(11):58-64
This article reports the latest results of an R&D effort to develop a prototype implementation of a dynamic policy-based network management (PBNM) system that can be used to configure and manage a secure network for a coalition environment across an unsecured wide area network. The prototype, based on a distributed architecture, includes capabilities for policy creation and management, dynamic policy negotiation, and dynamic policy provisioning. The policy negotiation facilitates the rapid deployment of a coalition network while the dynamic policy provisioning automates the configuration and management of network services including firewalls, virtual private network connections, routing, quality of service (QoS), and domain name services. Such a PBNM system enhances an organization's ability to react to network incidents identified by a network situational awareness assessment. Although the focus of the current research is a military coalition environment, the system can be used in any distributed enterprise or collaborative environment 相似文献
75.
Design optimization of 3D steel structures: Genetic algorithms vs. classical techniques 总被引:1,自引:0,他引:1
María Belén Prendes Gero Antonio Bello García 《Journal of Constructional Steel Research》2006,62(12):1303-1309
In this paper an elitist genetic algorithm (GA) developed by the authors is compared with common commercial solutions for complex structural optimization. After its prior validation on two-dimensional (2D) structures, the GA was tuned and improved in order to obtain structural elements with minimum weights that satisfy the ultimate limit states of the applicable building code. Subsequently, the same spatial structures were optimized using a commercial structural analysis program. Finally, the cost and weight improvements obtained using the GA, although at a higher computational cost, are discussed. 相似文献
76.
AE Pérez Rodríguez L Expósito Rivas O Rodríguez Leyva A Goyenechea Hernández 《Canadian Metallurgical Quarterly》1992,44(2):145-148
A discussion is carried out about the experiences with the application of rimantadine and amantadine to patients with influenza. The basic general results consisted in the fact that 2 of the 74 patients treated had a high cure percent (> 68.0%) within the first 72 hours after using the drug. No new diseased were found among the 40 contacts to whom chemoprophylaxis was applied. There were only 3.9% adverse reactions among the total number of people treated with amantadine. 相似文献
77.
Patrícia Carvalho de Souza André Salim Khayat Igor Chamon Seligmann Rommel Mario Rodríguez Burbano 《Biocell》2008,32(2):207-210
The collared peccary (Tayassu tajacu) is widely distributed over the American continent, being found from the south of the USA to the north of Argentina. In Brazil, it is spread all over the country, being one of the potential species to be raised in captivity. Therefore, the cytogenetic techniques could be a potential tool for reproductive monitoring of animals raised in captivity, mainly when destined for commercial purposes. This study had the objective of determining the chromosome number of two populations raised in captivity and characterizing them by GTG banding. For this purpose, an analysis was made of mitotic metaphases obtained from lymphocyte cultures made from blood samples of 11 animals, six of which from the Northeast and five from the North of Brazil. The results of this analysis showed the same karyotype pattern for the species (2n=30 chromosomes and NF=48), besides corresponding to the South American pattern of the species, i.e., without a translocation between autosomes 1 and 8, chromosome X acrocentric, and no differences were found between the two populations studied. However, chromosomal polymorphisms were observed compared to data from the literature on populations from North and South America. 相似文献
78.
Anna Grazia Mignani Peter R. Smith Leonardo Ciaccheri Antonio Cimato Graziano Sani 《Sensors and actuators. B, Chemical》2003,90(1-3):157-162
In spectral nephelometry, absorption spectroscopy and nephelometry are innovatively combined to provide simultaneous online monitoring of color and turbidity of edible oils. Spectral nephelometry instrumentation consists of an optoelectronic device that measures the absorption spectrum of the oil sample at different angles. Data processing, carried out by principal component analysis (PCA), allows identification of the oil sample and creates a two-dimensional map as a fingerprint of oil types. 相似文献
79.
Reda Karoum Antonio de Lucas-Consuegra Fernando Dorado Jose Luis Valverde Alain Billard Philippe Vernoux 《Journal of Applied Electrochemistry》2008,38(8):1083-1088
The electrochemical promotion of catalysis (EPOC) of propene combustion was investigated using Pt sputtered thin film on an
O2− conductor, 8 mol% Y2O3-stabilized-ZrO2 (YSZ). In order to separate the influence of the thermal migration of the O2− oxide ions from the electrolyte to the catalyst surface and the impact of an electrical polarization on the catalytic activity,
several light-off experiments (cool down and heat up procedures) were successively performed under different polarizations,
i.e. OCV, +2 and −2 V. These experiments have clearly shown that the presence of O2− (thermally or electrochemically induced) inhibits the catalytic activity of the platinum for the propene deep oxidation.
These results demonstrate the importance to define a normalized rate enhancement ratio, ρ
n
, from a reference value of the catalytic rate corresponding to a Pt surface state free of O2− ions. 相似文献
80.
Antonio Sarcos-Portillo Alfredo Navarro-Cerpa Hildrun García-Legl 《Canadian Metallurgical Quarterly》2003,8(4):223-228
In 1997 and 1999, inspection works were carried out in the 384 cable stays of the six central piers of General Rafael Urdaneta Bridge, located in Maracaibo, Venezuela. Inspection indicated the presence of water and significant settlings in the sockets of the cables and corrosion along each cable and socket. The tension of the cables was also measured, and differences of up to 30% in the tension of the cables of some of the 24 groups corresponding to the six central piers (four groups of 16 for each pier) were found. The results suggested the need to retension the cables. This paper shows the outcome of the inspection and indicates the procedure and results of the process of retension, finished in July 2000. 相似文献