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排序方式: 共有659条查询结果,搜索用时 62 毫秒
31.
S. Almaviva I. Ciancaglioni R. Consorti F. De Notaristefani C. Manfredotti Marco Marinelli E. Milani A. Petrucci G. Prestopino C. Verona G. Verona-Rinati 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2009,608(1):191-194
A synthetic single crystal diamond Schottky diode, in a p-type/intrinsic/metal structure, deposited by Chemical Vapour Deposition (CVD) and operating in photovoltaic regime, with no external bias voltage applied, was tested as a dosimeter for Intensity Modulated Radiation Therapy (IMRT) applications. The device response was compared with dose measurements from two commercial ionization chambers and a 2D diode array in an IMRT prostate cancer treatment plan. The obtained results indicate that CVD synthetic single crystal diamond-based dosimeters can successfully be used for highly conformed radiotherapy and IMRT dosimetry, due to their small size and high sensitivity per unit volume. 相似文献
32.
Magalhaes KD Costa LS Fidelis GP Oliveira RM Nobre LT Dantas-Santos N Camara RB Albuquerque IR Cordeiro SL Sabry DA Costa MS Alves LG Rocha HA 《International journal of molecular sciences》2011,12(5):3352-3365
In the present study, six families of sulfated polysaccharides were obtained from seaweed Dictyopteris delicatula by proteolytic digestion, followed by acetone fractionation and molecular sieving on Sephadex G-100. Chemical analyses demonstrated that all polysaccharides contain heterofucans composed mainly of fucose, xylose, glucose, galactose, uronic acid, and sulfate. The fucans F0.5v and F0.7v at 1.0 mg/mL showed high ferric chelating activity (~45%), whereas fucans F1.3v (0.5 mg/mL) showed considerable reducing power, about 53.2% of the activity of vitamin C. The fucan F1.5v presented the most prominent anticoagulant activity. The best antiproliferative activity was found with fucans F1.3v and F0.7v. However, F1.3v activity was much higher than F0.7v inhibiting almost 100% of HeLa cell proliferation. These fucans have been selected for further studies on structural characterization as well as in vivo experiments, which are already in progress. 相似文献
33.
Mauro Epifani Marco Alvisi Luciana Mirenghi Gabriella Leo Pietro Siciliano Lorenzo Vasanelli 《Journal of the American Ceramic Society》2001,84(1):48-54
A chloride-based inorganic sol–gel route was used for preparing pure and metal (osmium, nickel, palladium, platinum)-doped SnO2 sol. SnCl4 was first reacted with propanol, then the resulting compound was hydrolyzed and subsequently mixed with solutions of the metal dopants. The obtained sols were used for depositing thin films by spin coating or for preparing powders by solvent evaporation at 110°C. FTIR spectroscopy and thermal analysis of the powders revealed that chlorine still bound to tin stabilized the sol against gelation by hindering the condensation reactions. Film characterizations showed that platinum and palladium, unlike nickel and osmium, were likely to form nanoparticles in the SnO2 lattice. This result was discussed with regard to the different ways that platinum and palladium, on one hand, and nickel and osmium, on the other, modified the growth of SnO2 grains and the film roughness and morphology. Dopants that formed nanoparticles (platinum, palladium) resulted in the roughest film, while dopants that did not form particles (nickel, osmium) resulted in SnO2 grain size very close to that of pure SnO2 . 相似文献
34.
Giorgio Abbiati Fabio Marinelli Elisabetta Rossi Antonio Arcadi 《Israel journal of chemistry》2013,53(11-12):856-868
The peculiar features of gold(III) and gold(I) species include exceptional carbophilicity and, at the same time, lone pair affinity. Such a combination offers many advantages for the development of more sustainable approaches to the synthesis of indole derivatives from readily available 2-alkynylanilines. This mini-review critically summarizes the literature reports in this field, with the aim to encourage further research activities in this promising area. 相似文献
35.
Valeriano Lanese Danilo Spasiano Raffaele Marotta Ilaria Di Somma Luciana Lisi Stefano Cimino Roberto Andreozzi 《International Journal of Hydrogen Energy》2013
A new photocatalytic system consisting of two subsystems – Cu0/Cl−/H+/UVssr and CuII/H+/TiO2/formic acid/UVssr – is proposed as a tool to produce hydrogen by reforming an organic species. Formic acid is used as hole scavenger during the experimental runs. An experimental campaign is carried out to demonstrate that the systems can generate hydrogen and to assess how the generation rate depends upon experimental conditions such as copper and TiO2 loads, chloride and proton ions, and formic acid concentrations. A strong dependence of the Cu0/Cl−/H+/UVssr subsystem reactivity upon copper load, chloride concentration and pH is observed. The investigation on the complete system, starting from zero-valent copper, indicates that the addition of TiO2 and formic acid to the Cu0/Cl−/H+/UVssr subsystem does not result into any gain in terms of hydrogen produced and, renders the system totally unreactive under some conditions. On the other hand, when a complete system, starting from cupric ions, is adopted, hydrogen production is observed also for prolonged reaction times with a surplus of hydrogen production with respect to that generated by the Cu0/Cl−/H+/UVssr subsystem with the same Cu0 starting load and in absence of TiO2 and sacrificial agent. 相似文献
36.
Marcelo A. V. Souza Luiz Claudio de Santa Maria Marcos A. S. Costa Wang S. Hui Luciana C. Costa Hiram C. Araujo Filho Sandro C. Amico 《Polymer Bulletin》2011,67(2):237-249
Phosphinic-derivative poly(styrene-co-divinylbenzene)-based on PS–DVB copolymers with different porosity degrees have been
prepared by aromatic electrophilic substitution reaction using PCl3/AlCl3 followed by base-promoted hydrolysis. The phosphorylation reaction was analyzed by infra-red spectroscopy (FTIR), scanning
electron microscopy (SEM), and thermogravimetry (TG/DTG). In addition, the phosphorous content of the phosphorylated copolymers
was determined by spectrophotometry using the method based on sodium molybdate reactant so that the extension of that modification
could be assessed. The performance of the phosphorylated resins in the extraction of Pb2+ from aqueous solutions in a batch system was also evaluated. The Pb2+ content was determined by atomic absorption spectrometry (AAS). These materials presented excellent extraction capacity under
the contact time of 30 min and pH 6. 相似文献
37.
L. B. Da Silva A. L. Marinelli R. E. S. Bretas A. Rúvolo‐filho 《Polymer Engineering and Science》2002,42(8):1694-1709
In this work the thermal and transport properties of dichloromethane in blends of a bottle‐grade polyethylene terephthalate copolymer, PET, and a liquid crystalline polymer, LCP, were measured. Thermal characterizations of the blends were made by modulated differential scanning calorimetry and dynamic mechanical thermal analyses. An approximated LCP “bulk orientation” was also calculated by wide angle X‐ray diffraction. The morphology was analyzed by scanning electron microscopy. The resulting sorption curves of pure PET, and the B20, B40 and B60 blends were sigmoid type curves, while the sorption curve of the B80 blend was a two‐stage type curve. The diffusion coefficients of the B20 and B40 blends were found to be the lowest of all the blends. These low diffusivities were attributed to the occurrence of strong long‐range and short‐range interactions between the PET and the LCP in the B20 and B40 blends, and also to the perfection of the PET crystals in the B20 blend. 相似文献
38.
Obesity is a multifactorial pathology currently considered one of the main public health problems. Its prevalence is increasing dramatically in the last decades, reaching huge rates in Brazil and many other countries. Regardless of the factors associated with genetic predisposition, this pathology is often associated with abnormal food intake, and also with high consumption of caloric foods and sedentary habits. Thus, obesity is the result of an imbalance between food intake and energy expenditure. One of the greatest research interests in nutrition has currently been the dietetic determinants that may exert an influence on the process of food intake, as well as the role of foods on physiological, physical and chemical factors most related to the processes of satiation and satiety. Based on these aspects, this paper analyzes several research works to gain a better insight of the dietetic factors affecting food intake and body weight regulation. 相似文献
39.
Software architecture design is an interactive, complex, decision‐making process. Such a design process involves the exploration, evaluation, and composition of design alternatives. Increasingly, new computer‐aided tools are available to help designers in these complex activities. However, these tools do not know how design is actually done, in other words, by means of which design activities the final artefact was obtained. In fact, the architectural design knowledge exclusively rests in the mind of designers, and there is an urgent need to move it, as much as possible, to a computer‐supported environment that enables the capture of this type of knowledge. This contribution addresses this need by introducing a model for capturing how products under development are generated and transformed along the software architecture design process. The proposed model follows an operational perspective, where architectural design decisions are modelled by means of sequences of operations that are applied on the design products. Situation calculus is used to formally express the existence of an object in a given state of a design process. In addition, this formalism allows us expressing without ambiguities when an operation can be performed in a specific state of the design process. 相似文献
40.
Luciana A. Tacon 《Drying Technology》2013,31(5):841-852
The aim of this study was to evaluate the effects of paste properties on residence time during drying in a spouted bed dryer with inert bodies. The effect of paste solids content, surface tension, and viscosity on the residence time distribution and the mean residence times were studied using factorial experimental designs. The inert bodies used were glass and polyethylene beads. The mean residence times varied from 13.6 to 16.3 and 12.2 to 17.7 min for drying on glass and polyethylene beads, respectively. The analysis of variance showed that mean residence times significantly depended on solids content and surface tension for glass beads and also on viscosity for polyethylene beads. The residence time distributions for all conditions studied fitted well to the perfect mixing cell when applying the continuous stirred vessels in series model analysis. The powder density, flowability, and particle size depended on paste properties and inert type. 相似文献