253 resultados para CNF-monolith
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An in-situ modified sol-gel method for the preparation of a Ni-based monolith-supported catalyst is reported. With the presence of a proper amount of plasticizer and binder, and at an optimized pH value, the stable boehmite sol was modified with metal ions (Ni, Li, La) successfully without distinct growth of the particle size. Monolith-supported Ni-based/gamma-Al2O3 catalysts were obtained using the modified sol as the coating medium with several cycles of dip-coating and calcination. Combined BET, SEM-EDS, XRD and H-2-TPR investigations demonstrated that the derived monolith catalysts had a high specific surface area, a relatively homogeneous surface composition, and a high extent of interaction between the active component and the support. These catalysts showed relatively stable catalytic activities for partial oxidation of methane (POM) to syngas under atmospheric pressure. The monolith catalysts prepared by this sol-gel method also demonstrated an improved resistance to sintering and loss of the active component during the reaction process.
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A silica-based monolithic capillary column was prepared via a sol-gel process. The continuous skeleton and large through-pore structure were characterized by scanning electron microscopy (SEM). The native silica monolith has been successfully employed in the electrochromatographic separation of beta-blockers and alkaloids extracted from traditional Chinese medicines (TCMs). Column efficiencies greater than 250000 plates/m for capillary electrochromatography (CEC) separation of basic compounds were obtained. It was observed that retention of basic pharmaceuticals on the silica monolith was mainly contributed by a cation-exchange mechanism. Other retention mechanisms including reversed-phase and normal-phase mechanisms and electrophoresis of basic compounds also played a role in separation. A comparison of the differences between CEC and capillary zone electrophoresis (CZE) separation was also discussed.
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Loidi (Lazaroa 4:74. 1983) corrigió en contra del CNF el nombre de la asociación "Chenopodio-Oxalidetum violaceae Br-Rl. 1967", basándose en la determinacion errónea de la especie de Oxalis presente en la comunidad, ya que se trata de Oxalis latifolia Kunth y no de O. violacea L., según experiencia directa y referencias anteriores (cf. LAINZ, Collect. Bot. Barcelona 5 (3): 684, y DÍAZ GONZÁLEZ. Rev. Fac. Cienc. Oviedo, 15 (2): 482). Subsiguientemente, propuso el nombre Oxalidi latifoliae-Veronicetum persicae Br-Rl. 1967 corr. Loidi.
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Rivas-Martínez (Anal. Inst. Bot. Cavanilles 21(1): 134. 1963) describe una asociación de cervunales carpetanos para la que propone el nombre «Luzulo-Juncetum ellmanii as. nova», la que sinonimiza con la asociación Luzula sudetica-Pedicularis sylvatica Tx. & Oberd. 1958. descrita en la excursión de la IPE de la misma Sierra de Guadarrama.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Current research stresses the importance of parent involvement in their children 's academic development. Parents reading and writing with their young children is shown to prepare them for the benefits of for ma I education. Studies completed on parent participation in early literacy activities have tended to look at mothers ' role. Few researchers have investigated the contributions fathers have made. The results of a study completed on father-child early literacy practices are presented. Fathers reported engaging in reading and writing activities with their children for three reasons: To prepare their children for school, to bond with their children, and to assist their children in language skill development. Recommendations are provided on how to encourage fathers to participate in early literacy practices
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Both strain and damage sensing properties on carbon nanofiber cement composites (CNFCC) are reported in the present paper. Strain sensing tests were first made on the material’s elastic range. The applied loading levels have been previously calculated from mechanical strength tests. The effect of several variables on the strain-sensing function was studied, e.g. cement pastes curing age, current density, loading rate or maximum stress applied. All these parameters were discussed using the gage factor as reference. After this first set of elastic experiments, the same specimens were gradually loaded until material’s failure. At the same time both strain and resistivity were measured. The former was controlled using strain gages, and the latter using a multimeter on a four probe setup. The aim of these tests was to prove the sensitivity of these CNF composites to sense their own damage, i.e. check the possibility of fabricating structural damage sensors with CNFCC’s. All samples with different CNF dosages showed good strain-sensing capacities for curing periods of 28 days. Furthermore, a 2%CNF reinforced cement paste has been sensitive to its own structural damage.
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Mode of access: Internet.
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Literature cited: p. 147-155.
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"An extension of Technical bulletin no. 1179, Evaluation of agricultural hydrology by monolith lysimeters, 1944-55."
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Two simple, reproducible methods of preparing evenly distributed Au nanoparticle containing mesoporous silica monoliths are investigated. These Au nanoparticle containing monoliths are subsequently investigated as flow reactors for the selective oxidation of cyclohexene. In the first strategy, the silica monolith was directly impregnated with Au nanoparticles during the formation of the monolith. The second approach was to pre-functionalize the monolith with thiol groups tethered within the silica mesostructure. These can act as evenly distributed anchors for the Au nanoparticles to be incorporated by flowing a Au nanoparticle solution through the thiol functionalized monolith. Both methods led to successfully achieving even distribution of Au nanoparticles along the length of the monolith as demonstrated by ICP-OES. However, the impregnation method led to strong agglomeration of the Au nanoparticles during subsequent heating steps while the thiol anchoring procedure maintained the nanoparticles in the range of 6.8 ± 1.4 nm. Both Au nanoparticle containing monoliths as well as samples with no Au incorporated were tested for the selective oxidation of cyclohexene under constant flow at 30 °C. The Au free materials were found to be catalytically inactive with Au being the minimum necessary requirement for the reaction to proceed. The impregnated Au-containing monolith was found to be less active than the thiol functionalized Au-containing material, attributable to the low metal surface area of the Au nanoparticles. The reaction on the thiol functionalized Au-containing monolith was found to depend strongly on the type of oxidant used: tert-butyl hydroperoxide (TBHP) was more active than H2O2, likely due to the thiol induced hydrophobicity in the monolith.
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This paper summarises the development of a machine-readable model series for explaining Gaudi's use of ruled surface geometry in the Sagrada Familia in Barcelona, Spain. The first part discusses the modeling methods underlying the columns of the cathedral and the techniques required to translate them into built structures. The second part discusses the design and development of a tangible machine-readable model to explain column-modeling methods interactively in educational contexts such as art exhibitions. It is designed to explain the principles underlying the column design by means of physical interaction without using mathematical terms or language.
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This paper describes an extended case-based reasoning model that addresses the notion of situatedness in designing through constructive memory. The model is illustrated through an application for predicting the corrosion rate for a specific material on a specific building.