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81.
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PaulA. Stocks PatrickG. Bray VictoriaE. Barton Mohammed Al‐Helal Michael Jones NunaC. Araujo Peter Gibbons StephenA. Ward RuthH. Hughes GiancarloA. Biagini Jill Davies Richard Amewu AmyE. Mercer Gemma Ellis PaulM. O'Neill 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2007,119(33):6394-6399
84.
J. Araujo R. Ortíz A. López-Rivera J. M. Ortega M. Montilla D. Alarcón 《Journal of Solid State Electrochemistry》2007,11(3):407-412
The simultaneous electrodeposition of the system Cu–In–Se was investigated. The study was carried out at pH 8.5 using diethylentriamine
as complexing agent for the Cu+2 ion. The synthesis of CuInSe2 semiconductor thin films was carried out by electrodeposition on different substrates [indium–tin oxide (ITO) on glass, aluminum
and type 304 steel]. The simultaneous codeposition of the Cu, In, and Se was achieved by constant potential electrolysis technique
in aqueous solutions containing the elements that conform this material. The deposits of CuInSe2 were about 4 μm thick, which is thick enough for the photovoltaic effect to take place. The as-deposited films were characterized
by atomic emission spectroscopy with inductive coupling plasm (AES-ICP) and scanning electronic microscopy (SEM). Annealed
films were characterized X-ray diffraction, optical NIR spectroscopy, and photoelectrochemical studies The films were obtained
with a well-defined composition, very close to the expected one. Homogeneous deposit with chalcopyrite structure was produced.
A In2O3 phase was also observed. Annealing of the film improved the crystallinity of the films. Good photo response, an appropriate
absorption coefficient, and a band gap of 1.09 eV were obtained. 相似文献
85.
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Daniel C. Lima Ana M.P. dos Santos Rennan G.O. Araujo Ieda S. Scarminio Roy E. Bruns Sergio L.C. Ferreira 《Microchemical Journal》2010,95(2):222-226
The development of a homogeneity study during the preparation of a wheat flour laboratory reference material (LRM) for use in the quantification of metals and metalloids is reported. Inductively coupled plasma optical emission spectrometry (ICP OES) was used with validation performed using a certified reference material of wheat flour furnished by the National Institute of Standards and Technology (NIST). Copper, iron, manganese, phosphor, strontium and zinc were studied in a within-bottle homogeneity test whereas barium, copper, iron, zinc, manganese, strontium, phosphor and calcium were included in a between batch homogeneity study. Standard univariate analysis of variance (ANOVA) was performed for all analytes. Furthermore an alternative multivariate analysis for homogeneity is proposed by performing ANOVA of principal component scores and by inspection of principal component score graphs and hierarchical cluster analysis dendrograms. The ANOVA F-tests performed on both, the univariate and multivariate parameters, were not significant at the 95% confidence level and indicated homogeneous wheat flour samples. A 10 kg amount of material was processed, which was distributed in 100 bottles, each containing 100 g. For the between-bottle homogeneity test, three replicates were taken from each of 10 bottles selected of the 100 bottles obtained. The results were evaluated using an F-test, which demonstrated no significant difference for the between-bottle results. It is indicative that this material is homogeneous. Afterwards, the influence of the sample mass on the homogeneity of the material was also evaluated by quantification of the elements for 100, 300, 500, 700 and 1000 mg sample masses with all the experiments being performed in triplicate. The F-test was also used for evaluation of these results and demonstrated that the material is homogeneous for masses taken in the 100 to 1000 mg range. All these results were further evaluated employing the principal component analysis (PCA) and hierarchical cluster analysis (HCA) multivariate techniques. Both techniques also demonstrated that the material is perfectly homogeneous for use as laboratory reference material. 相似文献
87.
L. C. Mendes D. F. Silva L. J. F. Araujo A. S. Lino 《Journal of Thermal Analysis and Calorimetry》2014,116(3):1461-1469
The applicability of thermogravimetry (TG) coupled to single photon ionization time-of-flight mass spectrometry (TG-SPI-TOFMS) for evolved gas analysis (EGA) of coffee is demonstrated in this study. Coffee is a chemically well-known complex food product of large scientific and commercial interest. The roasting process of single green coffee beans (Arabica, Robusta) was simulated in the TG-SPI-TOFMS device, and the chemical composition of the evolved roasting gases was monitored on-line. Additionally, roasted and ground coffee powders of different types and brands as well as instant coffee were successfully investigated. For example, the diterpenes cafestol and kahweol can be detected among many other roasting products. These compounds can be of particular interest for quality control of coffee. It is shown that kahweol can be used as a tracer compound to discriminate arabica coffee species from robusta species. 相似文献
88.
Célio L. Cavalcante Jr Diana C.S. Azevêdo Irla G. Souza A. Cristina M. Silva Odelsia L.S. Alsina Verôonica E. Lima Antonio S. Araujo 《Adsorption》2000,6(1):53-59
This paper presents experimental results for equilibrium and diffusion of C8 aromatics in laboratory synthesised crystals of AlPO4-11. The samples were prepared by the hydrothermal method, starting from pseudobohemite (CONDEA), 85% phosphoric acid, water and di-isopropilamine as organic template. Adsorption and diffusion data were obtained mainly by gravimetry at temperatures between 60–100°C. Saturation capacities were found in the range of 4 wt%. Equilibrium constants were estimated using virial plots yielding heats of adsorption between 10–12 Kcal/mol at low coverage. Intracrystalline diffusivities at higher temperatures (150–180°C) were also measured, using the Zero-Length-Column (ZLC) method. Diffusivities from both methods (gravimetric and ZLC) agreed reasonably well and followed a typical Arrhenius behaviour, with low activation energy (ca. 7 Kcal/mol). 相似文献
89.
90.
Paulo Eliandro da Silva Júnior Natlia Maria de Araujo Flavio da Silva Emery 《Journal of heterocyclic chemistry》2015,52(2):518-521
α‐xiloidone is an interesting chromene that are structurally related to lapachones; in this work, we selectively synthesized α‐xiloidone from the reaction of lawsone 1 with 3,3‐chloro‐3‐methylbut‐1‐yne under copper/I2 catalysis via propargyl Claisen rearrangement. 相似文献