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排序方式: 共有901条查询结果,搜索用时 546 毫秒
1.
Roberto C. Dante Pablo Martín-Ramos Pedro Chamorro-Posada Dario Rutto José Vázquez-Cabo Denisse G. Dante 《Fullerenes, Nanotubes and Carbon Nanostructures》2020,28(7):533-540
AbstractIn this work, a new g-C3N4-based Z-scheme with γ-Fe2O3 and β-Ag2Se both n-type semiconductors, and graphite to favor electron exchange is presented. The composite material was studied by XRD, FTIR, UV-Vis, TEM, XPS, TGA, DSC and TOF-SIMS, and the ability of this photocatalytic system to act as a photo-reductant was assessed using crystal violet (CV+) dye. Solar light driven photo-reduction of CV+ in the presence of tri-sodium citrate evidenced a synergistic enhancement of the activity of the composite toward reduction, with ~20 times higher conversion rates per unit of surface area than those of g-C3N4. Photo-oxidation experiments under Xe lamp irradiation in the presence of H2O2 also showed that the AgFeCN composite featured a higher activity (~8×) than g-C3N4. This Z-scheme may deserve further study as a photo-reductant to obtain hydrogen or hydrogenated compounds. Moreover, the use of CV+ may represent a facile procedure that can aid in the selection of new photocatalysts to be used in hydrogen production. 相似文献
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Summary In this study, new hydrogels in rod shape were prepared from N-acryloyl-TRIS(hydroxymethyl)aminomethane (NAT) using ethylene glycol dimethacrylate (EGDMA) or N,N’methylenebisacrylamide (BIS) as crosslinking agent, dimethylformamide (DMF) as solvent and benzoyl peroxide (BPO) as initiator. In most cases, 2-hydroxyethyl methacrylate (HEMA), acrylamide (Aam) or acrylic acid (Aac) were used as co-monomers. The polymeric matrices obtained by free radical polymerization exhibited different properties by changing crosslinker, crosslinker concentration, co-monomer and initial NAT/co-monomer mole ratio. Besides, hydrogels from HEMA, Aam and Aac with BIS in absence of NAT were prepared under the same experimental reaction conditions in order to compare the properties of these products with those synthesized from NAT and the respective co-monomers. Some of the final products were selected to perform urea release assays, conducted through swelling-controlled release. Urea was chosen as “model” plant fertilizer agent. 相似文献
5.
Anthony Hendrikus Overmars Dario John Toncich 《International Journal of Flexible Manufacturing Systems》1994,6(4):311-331
This paper presents a critical evaluation of existing FMS architectures and the academic and industrial design and development strategies used during their formulation. The paper seeks to address the need for, and value of, existing architectures within the industrial arena. More importantly however, this paper puts forward a new two-tier distributed control architecture for FMS based upon new (real-time) networkable DSP servo control methodologies developed by one of the authors for Softronics in Australia. The ramifications of these methodologies are substantial, not only in terms of FMS control, but in the overall simplification of such systems and the development of flexible fixturing devices over the coming decade. This paper also postulates on how new FMS architectures can be developed from such technologies and details why such architectures could be more appropriate to industry needs than those that are currently in existence. 相似文献
6.
The free fraction of pertechnetate in 99Tcm radiopharmaceuticals has to be tested for quality control reasons in line with the European Pharmacopoeia. Such quality control is often performed by miniaturized chromatographic methods. There are several recommended methods in the literature for quality control of the same radiopharmaceuticals, though it is unlikely that all methods are equivalent. Some of these methods were compared, taking into account different parameters (spot size, time required, analytical artifacts, true separation and shape of the chromatographic peaks, ease of handling), to verify the best method for the control of each radiopharmaceutical. It would appear that instant thin layer chromatography silica gel is the best support for these miniaturized methods, using MEK as solvent to check DTPA, DMSA, gluconate, pyrophosphate, medronate and phytate; NaCl 20% solution is the best solvent for IDA derivatives, human albumin and albumin particles (microspheres, macroaggregates). 相似文献
7.
This paper deals with the development of new synthesis techniques for functional materials such as Yttria Stabilized Zirconia (YSZ) used in the field of thermal barriers coatings. Currently, Thermal Barrier Coatings (TBCs) are manufactured by dry route technologies (EB-PVD or plasma spray) but such methods are directional and often require costly investments and complicated operations. We have carried out significant work aimed at developing sol-gel routes, which are nondirectional methods, to prepare, by suitable chemical modifications, nanocrystalline materials with a controlled morphology. The main advantage of this method is to decrease the crystallization temperature, much lower than the conventional processes, allowing the synthesis of reactive powders with nanometric particles size. In this paper, the formulation of an alkoxide sol has been optimized in order to obtain homogeneous YSZ films. Nature and quantity of binders have been studied. Superalloys have been then immersed in the sol and withdrawn at several controlled rates before being annealed at different temperatures. The films microstructures have been investigated using scanning electron microscopy. It appears that the combination of a slower withdrawal speed (17 cm/min) with a 3 wt.% content of DBP allows to obtain the most homogeneous and the thicker coatings. Moreover, SEM-FEG observations have shown that the deposit is present all over the rough surface of the substrate and is composed of two morphologies: a YSZ thin covering film and a thicker discontinuous layer duplicating the substrate topography. 相似文献
8.
Dario Pasini Luigi Garlaschelli Elza Bontempi Laura E. Depero 《Fullerenes, Nanotubes and Carbon Nanostructures》2007,15(5):367-378
The synthesis of a series of polymers and cyclopolymers bearing crown ethers of differing structure and affinities towards primary ammonium ions is discussed. These polymers have been tested in their efficiency to form structurally homogeneous thin films when blended with an amphiphilic C60 compound containing a primary ammonium ion functional group. The X-ray reflectivity characterization of the films revealed that the polymer bearing the crown ether with the least affinity for primary ammonium ions, but having the highest degree of polymerization, is the most effective in forming structurally homogeneous thin films. 相似文献
9.
From "macro" to "micro" manipulation: models and experiments 总被引:1,自引:0,他引:1
A. Menciassi A. Eisinberg I. Izzo P. Dario 《Mechatronics, IEEE/ASME Transactions on》2004,9(2):311-320
This paper addresses various problems related to manipulation in the micro domain, a field which is increasingly important for research and application. Grasping and manipulating parts with size ranging between a few micrometers and about 1 millimeter (defined in this paper as "micro parts") are required for an increasing number of applications: the assembly of micro systems and micro machines; and the operation in tiny and unpredictable environments, such as for inspection and interventions in pipes and for micro surgery. The aim of this work is to find out similarities and differences between traditional manipulation and micro manipulation, by investigating which requirements are still valid and which must be redefined when the object size scales down. The similarities between the two application domains "macro" and "micro" are pointed out along with the differences, and both are taken into account for the evaluation of different grasping typologies. Dedicated models for the adhesion forces arising at the micro level are presented, preliminarily tested, and discussed. 相似文献
10.
The energy balance is discussed for the complex case of bronze or marble statuary horses and particularly the four horses of San Marco in Venice. Having computed the coefficient of exchange between bronze and the atmosphere, the daytime overheating is evaluated for different seasons and orientations of the statues. The equations can be solved with reasonable approximation and both the past and future overheatings can be evaluated as a function of the growing surface weathering and blackening. Therefore, the present analysis points out the chief characteristics of both the diurnal cycle and the variation over the centuries of the response of the bronzes to atmospheric variables. 相似文献