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排序方式: 共有818条查询结果,搜索用时 15 毫秒
781.
Mahnaz Esteki Bahman Farajmand Yadollah Kolahderazi Jesus Simal-Gandara 《Food Analytical Methods》2017,10(10):3312-3320
Adulteration of almond powder samples with apricot kernel was solved by gas chromatographic fatty acid fingerprinting combined with multivariate data analysis methods (principal component analysis (PCA), PCA-linear discriminant analysis (PCA-LDA), partial least squares (PLS), and LS support vector machine (LS-SVM). Different almond and apricot kernel samples were mixed at concentrations ranging from 10 to 90% w/w. PCA and PCA-LDA methods were applied for the classification of almonds, apricot kernels, and mixtures. PLS and LS-SVM were used for the quantification of adulteration ratios of almond. Models were developed using a training data set and evaluated using a validation data set. The root mean square error of prediction (RMSEP) and coefficient of determination (R 2) of validation data set obtained for PLS and LS-SVM were 5.01, 0.964 and 2.29, 0.995, respectively. The results showed that the methods can be applied as an effective and feasible method for testing almond adulteration. 相似文献
782.
Precession electron diffraction‐assisted crystal phase mapping of metastable c‐GaN films grown on (001) GaAs 下载免费PDF全文
Francisco Ruiz‐Zepeda Yenny L. Casallas‐Moreno Jesus Cantu‐Valle Diego Alducin Ulises Santiago Miguel José‐Yacaman Máximo López‐López Arturo Ponce 《Microscopy research and technique》2014,77(12):980-985
The control growth of the cubic meta‐stable nitride phase is a challenge because of the crystalline nature of the nitrides to grow in the hexagonal phase, and accurately identifying the phases and crystal orientations in local areas of the nitride semiconductor films is important for device applications. In this study, we obtained phase and orientation maps of a metastable cubic GaN thin film using precession electron diffraction (PED) under scanning mode with a point‐to‐point 1 nm probe size beam. The phase maps revealed a cubic GaN thin film with hexagonal GaN inclusions of columnar shape. The orientation maps showed that the inclusions have nucleation sites at the cubic GaN {111} facets. Different growth orientations of the inclusions were observed due to the possibility of the hexagonal {0001} plane to grow on any different {111} cubic facet. However, the generation of the hexagonal GaN inclusions is not always due to a 60° rotation of a {111} plane. These findings show the advantage of using PED along with phase and orientation mapping, and the analysis can be extended to differently composed semiconductor thin films. Microsc. Res. Tech. 77:980–985, 2014. © 2014 Wiley Periodicals, Inc. 相似文献
783.
Alberto Clemente Francisco Balas M. Pilar Lobera Silvia Irusta Jesus Santamaria 《Aerosol science and technology》2013,47(8):867-874
A long-lasting generator of continuous silica nanoparticle aerosols based in a fluidized bed of glass beads coated with nanosized silica has been developed. The attrition resulting from the bubbling fluidized bed regime progressively detaches the silica coating from the glass beads, giving rise to a steady production of silica nanosized aerosols with median diameters from 100 to 250 nm depending on the initial size of the coating nanoparticles. Continuous aerosol production could be maintained for more than 12 h, and the nanoparticle concentration can be easily tuned in the range of 2000 to 14,000 #/cm3 by adjusting the fluidization and/or dilution flow rates. Copyright 2013 American Association for Aerosol Research 相似文献
784.
Wakako Araki Jesus Gonzalez-Julian Jürgen Malzbender 《Journal of the European Ceramic Society》2019,39(13):3660-3667
The creep behaviours of the dense and porous Cr2AlC ceramics were investigated, being the first study on creep behaviour of not only Cr2AlC but also porous MAX phase. Creep rates of rather dense (2% of porosity) and porous Cr2AlC (53% and 75%) were measured in the temperature range 1073–1473 K during heating and subsequent cooling after high temperature exposure. The compressive creep tests were performed under stress range of 1–12 MPa. Creep rates of porous Cr2AlC were higher than the ones of the rather dense material at lower temperature but lower at higher temperature, which can be attributed to effects of the formed oxide scale and some crack healing associated with the scale formation. A comparison of the creep rates with other refractory materials reveals favourable properties of the porous Cr2AlC. 相似文献
785.
786.
Sakonwan Kuhaudomlarp Samuel Walpole Dr. Clare E. M. Stevenson Dr. Sergey A. Nepogodiev Dr. David M. Lawson Dr. Jesus Angulo Prof. Robert A. Field 《Chembiochem : a European journal of chemical biology》2019,20(2):181-192
Glycoside phosphorylases (GPs) carry out a reversible phosphorolysis of carbohydrates into oligosaccharide acceptors and the corresponding sugar 1-phosphates. The reversibility of the reaction enables the use of GPs as biocatalysts for carbohydrate synthesis. Glycosyl hydrolase family 94 (GH94), which only comprises GPs, is one of the most studied GP families that have been used as biocatalysts for carbohydrate synthesis, in academic research and in industrial production. Understanding the mechanism of GH94 enzymes is a crucial step towards enzyme engineering to improve and expand the applications of these enzymes in synthesis. In this work with a GH94 laminaribiose phosphorylase from Paenibacillus sp. YM-1 (PsLBP), we have demonstrated an enzymatic synthesis of disaccharide 1 (β-d -mannopyranosyl-(1→3)-d -glucopyranose) by using a natural acceptor glucose and noncognate donor substrate α-mannose 1-phosphate (Man1P). To investigate how the enzyme recognises different sugar 1-phosphates, the X-ray crystal structures of PsLBP in complex with Glc1P and Man1P have been solved, providing the first molecular detail of the recognition of a noncognate donor substrate by GPs, which revealed the importance of hydrogen bonding between the active site residues and hydroxy groups at C2, C4, and C6 of sugar 1-phosphates. Furthermore, we used saturation transfer difference NMR spectroscopy to support crystallographic studies on the sugar 1-phosphates, as well as to provide further insights into the PsLBP recognition of the acceptors and disaccharide products. 相似文献
787.
Recovery of γ-oryzanol from rice bran oil byproduct using supercritical fluid extraction 总被引:1,自引:0,他引:1
The residue of fatty acids distillation from rice bran oil soapstock (RFAD-RBOS) is a byproduct from rice bran oil industry. It contains a large amount of γ-oryzanol, which is a valuable antioxidant. The main objective of this work was to investigate the recovery of γ-oryzanol from the RFAD-RBOS using supercritical fluid extraction (SFE). The Soxhlet technique was conducted in order to compare results with SFE. The influence of process parameters over SFE was evaluated in terms of global yield, γ-oryzanol content, γ-oryzanol recovery rate, and fatty acids composition. The mathematical modeling of SFE overall extraction curve (OEC) was also investigated. The condition of 30 MPa/303 K presented the maximum global yield (39 ± 1%, w/w), maximum γ-oryzanol recovery rate (31.3%, w/w), relatively high γ-oryzanol content (3.2%, w/w), and significant presence of monounsaturated and polyunsaturated fatty acids. The logistic model presented the best fit to experimental OEC. 相似文献
788.
Potable water as well as water for agriculture and industry is critical to human habitation on this planet. We have been squandering and polluting this precious resource and are now in need of finding cost competitive newer technologies for reclaiming this valuable life-sustaining liquid. Capacitive deionization (CDI) is an electrochemical water treatment process that holds the promise of not only being a commercially viable alternative for treating water but for saving energy as well. CDI works by sequestering ions, or other charged species, in the electrical double layer of ultracapacitors. While removing these ions, one actually stores capacitive energy. If one recovers this energy efficiently, this process likely consumes less power than any competing technology. This paper reviews current methods for treating water in comparison to the state of art of the CDI process. 相似文献
789.