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21.
Silvia Mendona Vieira Tarliane Maria Silva Maria Beatriz Abreu Glria 《Food chemistry》2010,119(1):7-11
The influence of processing on the levels of bioactive amines and proline as well as on some physico-chemical characteristics of concentrated orange juice was investigated. Samples were collected at seven points of a production line on three non-consecutive days, and analysed for the levels of 12 bioactive amines, proline, and reducing and non-reducing sugars, and for some physico-chemical characteristics. Among the amines analysed, only putrescine, spermidine and synephrine were found in the samples at all processing stages. Significant differences were observed for spermidine and total amine levels throughout processing. Synephrine and putrescine were resistant to processing. Proline levels changed significantly throughout processing, as did levels of reducing and non-reducing sugars. The pH varied from 3.59 to 3.72, acidity from 0.873 to 0.918 g citric acid/100 mL, and density from 1.0378 to 1.0970 g/mL. Among these parameters, pH, acidity and density were significantly affected by processing. 相似文献
22.
Alberto Ortega Rodrigo Escobar Sergio Colle Samuel Luna de Abreu 《Renewable Energy》2010,35(11):2514-2524
The Chilean government has determined that a renewable energy quota of up to 10% of the electrical energy generated must be met by 2024. This plan has already sparked interest in wind, geothermal, hydro and biomass power plants in order to introduce renewable energy systems to the country. Solar energy is being considered only for demonstration, small-scale CSP plants and for domestic water heating applications. This apparent lack of interest in solar energy is partly due to the absence of a valid solar energy database, adequate for energy system simulation and planning activities. One of the available solar radiation databases is 20–40 years old, with measurements taken by pyranographs and Campbell–Stokes devices. A second database from the Chilean Meteorological Service is composed by pyranometer readings, sparsely distributed along the country and available from 1988, with a number of these stations operating intermittently. The Chilean government through its National Energy Commission (CNE) has contracted the formulation of a simulation model and also the deployment of network of measurement stations in northern Chile. Recent efforts by the authors have resulted in a preliminary assessment by satellite image processing. Here, we compare the existing databases of solar radiation in Chile. Monthly mean solar energy maps are created from ground measurements and satellite estimations and compared. It is found that significant deviation exists between sources, and that all ground-station measurements display unknown uncertainty levels, thus highlighting the need for a proper, country-wide long-term resource assessment initiative. However, the solar energy levels throughout the country can be considered as high, and it is thought that they are adequate for energy planning activities – although not yet for proper power plant design and dimensioning. 相似文献
23.
J. M. Pardal S. S. M. Tavares M. P. Cindra Fonseca M. R. da Silva J. M. Neto H. F. G. Abreu 《Journal of Materials Science》2007,42(7):2276-2281
The magnetic properties and hardness of a Ni–Co–Mo–Ti maraging steel 300 grade were measured as function of aging temperature.
The austenite and martensite phase quantifications in the different heat treatment conditions were carried out by X-ray diffraction
using direct comparison method. The behavior of the hardening, magnetization saturation and coercive force against aging temperature
and time were explained taking into account the variation of austenite volume fraction with aging time and temperature. 相似文献
24.
I. Piñera C.M. Cruz Y. Abreu A. Leyva 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2008,266(22):4899-4902
The contribution from positrons to the displacements per atom (dpa) distribution induced by the gamma irradiation on YBCO superconducting slabs is presented. The procedure implemented previously by the authors was adapted to take into account the contribution from positrons to dpa induced by the gamma radiation. The results show that, when positrons are considered in the atom displacement process, the total dpa almost doubles at 10 MeV of incident gamma radiation. At that energy positrons contribute 7% more to the total dpa than electrons, although electrons maintain having the highest contribution up to about 8 MeV. 相似文献
25.
Effects of burning of biomass on satellite estimations of solar irradiation in Brazil 总被引:1,自引:1,他引:0
Atmospheric combustion products from forest fires in the Brazilian Amazon and ‘Cerrado’ regions during the dry season (July–October) induce systematic deviations on the routine satellite techniques for the assessment of solar energy resource information. This study, based on clear-sky days, has shown model overestimations of the incoming solar radiation as high as 44%. On the average, clear-sky model overestimation was four times larger than that found for clear-sky days in regions outside the biomass-burning season. A positive correlation between the combustion products of black carbon, total aerosols, CO, N2O, CH4, and the number of fire spots counted by the AVHRR sensor from the NOAA series satellites suggests a possible mechanism for the parameterization of these effects on the radiation transfer methods. 相似文献
26.
João Vicente-Neto Maria Cristina Bressan Peter Bitencourt Faria Josye Oliveira e Vieira Maria das Graças Cardoso Maria Beatriz de Abreu Glória Luis Telo da Gama 《Meat science》2010
Chemical composition and fatty acid profiles were determined in Caiman yacare meat originating from the neck and tail cuts of animals raised in the wild (n = 6) or in captivity (n = 6), slaughtered at a live weight of approximately 6 kg. All experimental methods were approved by the appropriate environmental protection agencies. Most chemical components were affected by the origin-cut interaction, with the tail cut of wild animals having the highest amount of intramuscular fat (19.2% of DM) and the lowest of moisture (71.8%) and protein (77.0% of DM). Yacare meat had low amounts of SFA (35.1%), which were similar (P > 0.05) in the cuts and origins studied. The total amount of PUFA was higher (P < 0.05) in wild (31.0%) than in captive animals (23.6%), and n − 3 fatty acids had means of about 5% and 2% for the same groups, respectively (P < 0.05). In general, the FA profile of intramuscular fat in yacare meat had a desirable PUFA/SFA ratio above 0.4. 相似文献
27.
A novel, simple and efficient method for the generation of Tikhonov (a.k.a. von Mises) random variates is proposed. In the proposed method, circular variates of a prescribed Tikhonov distribution pT(x;alpha,xi) are generated via the transformation of variates selected randomly, on a one-for-one basis, from a bank of K distinct Cauchy and Gaussian generators. The mutually exclusive probabilities of sampling from each of the Cauchy or Gaussian generators, as well as the variance and half-width parameters that specify the latter, are derived directly from the Cauchy, Gaussian and Tikhonov characteristic functions, all of which are either known or given in closed form. The proposed random mixture technique is extremely efficient in that a single pair of uniform random numbers is consumed in the generation of each Tikhonov (or von Mises) sample, regardless of the prescribed concentration and centrality parameters (alpha, xi), all requiring neither the rejection of samples, nor the repetitive evaluation of computationally demanding functions. Additional attractive features of the method are as follows. By construction, the first (dominant) N circular moments of Tikhonov variates generated with the proposed random mixture technique are the ones that best approximate their corresponding theoretical values, with errors measured exactly. The exact distribution of generated Tikhonov variates is determined analytically, and its (Kullback-Leibler) divergence to the exact Tikhonov PDF is shown also analytically to be negligible. Finally, the technique establishes a connection between Tikhonov and Gaussian variates which can be exploited, e.g., in the generation of piecewise-continuous pseudo-random functions with Tikhonov-distributed outcomes. 相似文献
28.
Renato Martins da Silva Bárbara Della Noce Camila Fernanda Waltero Evenilton Pessoa Costa Leonardo Araujo de Abreu Naftaly Wang’ombe Githaka Jorge Moraes Helga Fernandes Gomes Satoru Konnai Itabajara da Silva Vaz Jr. Kazuhiko Ohashi Carlos Logullo 《International journal of molecular sciences》2015,16(1):1821-1839
29.
Tiago Felipe de Abreu Santos Edwar Andrés Torres Antonio Jose Ramirez 《Welding International》2018,32(2):103-111
Duplex stainless steels are successful in a variety of applications such as the food industry, petrochemicals and plants for desalination of seawater, where high corrosion resistance and high mechanical strength are required. However, the beneficial microstructure may change during fusion welding steps, and it can compromise the performance of these materials. Friction stir welding is a solid-state process avoiding typical problems concerning solidification such as solidification cracks, liquation and segregation of alloying elements. Superduplex stainless steels can avoid unbalanced proportions of ferrite and austenite, formation of secondary deleterious phases and grain growth of ferrite in the heat-affected zone. Consolidated friction stir welded joints with full penetration 6 mm thick were obtained for UNS S32101 and S32205 duplex and S32750 and S32760 superduplex stainless steels. The friction stir welds were submitted to tensile tests indicating an improvement of strength in welded joints, showing increased yield and tensile strength for all studied cases. Regarding the microstructural characterization, an outstanding grain refinement was observed in the welded joint, achieving grain sizes as small as 1 μm. This refinement was associated with the combination of microstructural restoration mechanisms in the dual-phase microstructure promoted by severe deformation associated with a high temperature during the welding process. 相似文献
30.
The objective was to assess food consumption among children attending non-profit nurseries in the Federal District, Brazil.A representative sample was obtained and stratified by income. Food intake among 678 children, between 4 and 82 months old, was analyzed in nine nurseries using the 24-h dietary recall and direct food weighing methods. In children under 13 months old mean intake was above AI between 93.6 to 100% for carbohydrates, proteins, vitamins B1, B2, B12, B6, and zinc. In children from 7-12 months 56.5% presented iron consumption below EAR. Calcium intake was above AI for 35.4% of children over 1 year old. For vitamins with EAR values, the prevalence of inadequate consumption was 53.2% for vitamin E, and 90% for folate for children over 12 months old. Iron and zinc intake was above UL for 6.4% and 32.5% of children under 1 year old, and 1.5% and 5.3% for the remaining children, respectively. Lipid percentage distribution range among children between 13 and 47 months old was within the acceptable range for only 16.2%. Nonetheless, children between 36 and 82 months of both genders presented mean intake below energy requirements. Inadequate consumption observed for some nutrients points to the need for improvements in the standard of meals and nutritional assistance offered to children enrolled in charitably run nurseries in the Federal District. 相似文献