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排序方式: 共有98条查询结果,搜索用时 15 毫秒
31.
José J. Rios Elisabet Fernández-GarcíaMaría Isabel Mínguez-Mosquera Antonio Pérez-Gálvez 《Food chemistry》2008
Here we describe the profiles of volatile compounds from the thermal degradation of carotenoids present in oleoresins of marigold, tomato and paprika. The profiles obtained by SPME-GC were complex, with identical compounds, such as toluene and m-xylene, being detected in all three oleoresins. Intramolecular cyclisation is proposed as the main reaction mechanism in the formation of the volatile compounds detected; this process is activated by the thermal impact generated during the processing and is followed by a reaction of elimination in the chain or a heterolytic fragmentation reaction. The presence of other compounds, such as various methyl benzaldehydes or isophorone (1,1,3-trimethyl-3-cyclohexene-5-one), also indicates the concurrence of carotenoid oxidation reactions that affect either the central polyenoic chain or the end-groups (β or ε rings). Ethanone,1-(methylphenyl), (4prime-methylacetophenone) not previously reported as a compound resulting from the thermal degradation of carotenoids, was also characterised and the same mechanism is proposed for its formation. 相似文献
32.
33.
Meritxell Vilaseca Barbara Schael Xana Delpueyo Elisabet Chorro Esther Perales Tapani Hirvonen Jaume Pujol 《Color research and application》2014,39(6):549-558
This study analyzes the repeatability, reproducibility and accuracy of a new hyperspectral system based on a pushbroom sensor as a means of measuring spectral features and color of materials and objects. The hyperspectral system consisted of a CCD camera, a spectrograph and an objective lens. An additional linear moving system allowed the mechanical scanning of the complete scene. A uniform overhead luminaire with daylight configuration was used to irradiate the scene using d:45 geometry. We followed the guidelines of the ASTM E2214‐08 Standard Practice for Specifying and Verifying the Performance of Color‐Measuring Instruments that define the standards and latest multidimensional procedures. The results obtained are analyzed in‐depth and compared to those recently reported by other authors for spectrophotometers and multispectral systems. It can be concluded that hyperspectral systems are reliable and can be used in the industry to perform spectral and color readings with a high spatial resolution. © 2013 Wiley Periodicals, Inc. Col Res Appl, 39, 549–558, 2014 相似文献
34.
Elisabet Navarro-Tapia Laura Almeida-Toledano Giorgia Sebastiani Mariona Serra-Delgado
scar García-Algar Vicente Andreu-Fernndez 《International journal of molecular sciences》2021,22(5)
Anxiety and eating disorders produce a physiological imbalance that triggers alterations in the abundance and composition of gut microbiota. Moreover, the gut–brain axis can be altered by several factors such as diet, lifestyle, infections, and antibiotic treatment. Diet alterations generate gut dysbiosis, which affects immune system responses, inflammation mechanisms, the intestinal permeability, as well as the production of short chain fatty acids and neurotransmitters by gut microbiota, which are essential to the correct function of neurological processes. Recent studies indicated that patients with generalized anxiety or eating disorders (anorexia nervosa, bulimia nervosa, and binge-eating disorders) show a specific profile of gut microbiota, and this imbalance can be partially restored after a single or multi-strain probiotic supplementation. Following the PRISMA methodology, the current review addresses the main microbial signatures observed in patients with generalized anxiety and/or eating disorders as well as the importance of probiotics as a preventive or a therapeutic tool in these pathologies. 相似文献
35.
Arndt Lüder Elisabet Estévez Lorenz Hundt Marga Marcos 《The International Journal of Advanced Manufacturing Technology》2011,54(9-12):1077-1089
Engineering of manufacturing systems is one of the most important aspects within the life cycle of manufacturing systems in terms of cost. Within the engineering process, several engineering activities are executed by different experts commonly using specific tools for the design of the different parts of the system. To reduce engineering costs beneath, two main approaches arise. The first is based on the use of libraries of mechatronical units as reusable artifacts. In this case, manufacturing systems are represented as a hierarchy of mechatronic units. The second option is to achieve the seamless connection of the different engineering tools exploiting a common data exchange format. This latter approach allows avoiding both double engineering and faults within the engineering process. Within this paper, a novel approach combining both options is proposed, and its effects are analyzed through an example. It considers the application of mechatronical units within the engineering process of manufacturing systems as well as a common data exchange format for the logic information required for designing the control system within the engineering of manufacturing systems. The latter provides a data exchange format for the overall engineering process, including not only model information exchange but also its embedding. This paper discusses the benefits of the data exchange format for logic models in detail. 相似文献
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37.
Elisabet M G Thorstensson Dwayne R Buxton Jerome H Cherney 《Journal of the science of food and agriculture》1992,59(2):183-188
Lignin, a cell wall component, limits digestibility of plant cell walls. Brown midrib (bmr) mutants of forages have lignin with altered chemical composition compared with their normal counterparts. The objectives of this study were to determine if bmr lignin is more inhibitory to digestion than is normal lignin and if bmr has a consistent effect on rate of digestion across species and environments. Extent and rate of in-vitro cell wall digestion of normal and bmr stems of sorghum (Sorghum bicolor (L) Moench, two comparisons), millet (Pennisetum americanum (L) Leeke) and maize (Zea mays L, two comparisons) were determined. Samples were incubated in rumen fluid, and data were fitted with a first-order, nonlinear model to estimate concentrations of potentially digestible neutral detergent fibre (PDNDF), digestion rate of PDNDF, concentration of indigestible residue (IR), and lag time before digestion. The NDF, acid-detergent fibre (ADF), and acid-detergent lignin (ADL) analyses were conducted sequentially on undigested samples. The IR: ADL ratio was 37% greater for bmr than for normal plants, which indicates that bmr lignin inhibits digestion more than normal lignin per unit of lignin. Digestion rate of PDNDF was faster in bmr than in normal counterparts in one of the two sorghum comparisons (difference of 59%) and in the millet comparison (difference of 27%), but in neither maize comparison. The bmr mutants were lower than normal genotypes in NDF (9%) and ADL (47%) concentrations. The PDNDF concentration was 19% greater for bmr than for normal lines. Thus, decreased lignin concentration in bmr mutants increased the extent of NDF digestion but did not consistently increase the rate of digestion. 相似文献
38.
David Lloyd Tuomas Vainikka Lasse Murtomäki Kyösti Kontturi Elisabet Ahlberg 《Electrochimica acta》2011,56(14):21383
Kinetics of electron transfer of the Cu(I)/Cu(II) redox couple at a platinum electrode has been studied with chronoamperometry, cyclic voltammetry and impedance spectroscopy in a deep eutectic solvent consisting of choline chloride and ethylene glycol. At 25 °C, the reaction was found to be quasi-reversible with a relatively high rate constant k0 of 9.5 ± 2 × 10−4 cm s−1, and a charge transfer coefficient α of 0.25 ± 0.05. Diffusion coefficients for the Cu(I) and Cu(II) complexes were determined to be 2.7 ± 0.1 × 10−7 and 1.5 ± 0.1 × 10−7 cm2 s−1, respectively. The viscosity of the electrolyte was 41 ± 3 mPa s. The temperature dependency was also investigated. The activation energy of mass transfer was found to be 27.7 ± 1 kJ mol−1 and that of electron transfer 39 ± 7 kJ mol−1. Speciation of the Cu(I) and Cu(II) complexes was determined using UV–VIS spectroscopy, and the prevailing Cu(I) complex was found to be [CuCl3]2− and that of Cu(II) [CuCl4]2−. 相似文献
39.
The use of hardened high strength steel is found in applications where high wear resistance is required. The wear properties of high strength Boron steel are well known in applications with abrasive wear from stones, ore and other hard material. A unique concept of wear protection of rails is newly presented, a wear resistant cap made of hardened high strength Boron steel.Reducing the wear of rails and wheels and controlling the frictional behavior in the wheel/rail contact are two key issues for railway owners in order to reduce the increasing costs related to higher axle loads, higher speeds, more frequent traffic, etc. Therefore, the aim of this work has been to investigate and compare the tribological properties of Boron steel and UIC 1100 rail steel in contact with Blue Light wheel steel (AAR Class C (69-JDG-8)) under dry and water lubricated conditions in a two-disc tribometer. Advanced analytical instruments including 3D optical surface profiler, micro-hardness indenter, light microscope and SEM/EDS were used to analyze the results.Results from the experiments show that the friction coefficient in tests with Boron steel is more stable both in dry and water lubricated conditions than tests including UIC 1100 rail steel used in todays application. Surface damages seen from water lubricated tests on UIC 1100 rail steel are not seen on the surface of the Boron steel discs. In all tests, the wear decreased when water was added in the contact and friction was slightly decreased. 相似文献
40.
Longitudinal development of chlorophyll and phytoplankton assemblages in a regulated large river (the Ebro River) 总被引:2,自引:0,他引:2
Sabater S Artigas J Durán C Pardos M Romaní AM Tornés E Ylla I 《The Science of the total environment》2008,404(1):196-206
The distribution of chlorophyll and phytoplankton communities were compared to nutrient concentrations and hydrological parameters along the main stretch of the river Ebro. A progressive increase in planktonic chlorophyll was observed from the upper reaches to the middle section of the river. Chlorophyll reached a maximum (60-80 microg L(-1)) in the meandering section (downstream of the city of Zaragoza), where nutrient inputs (both N and P) and the residence time of the water are very high. In this meandering section phytoplankton assemblages consisted of large centric diatoms and Scenedesmus sp.pl. These longitudinal patterns were interrupted by the presence of three large reservoirs in the lower section of the river. In the section below the reservoirs, the shorter residence water time, the presence of the invasive zebra mussel, and the massive macrophyte development may explain the historical decrease in chlorophyll-a (from 20-45 microg L(-1) in the 1990s to the present 2-5 microg L(-1)). Phytoplankton densities were extremely poor in this section of the river, where large colonial Coelastrum sp.pl. and Pediastrum sp.pl. were the most characteristic taxa. 相似文献