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1.
Carotenoids are an essential component of cashew and can be used in pharmaceuticals, cosmetics, natural pigment, food additives, among other applications. The present work focuses on optimizing and comparing conventional and ultrasound-assisted extraction methods. Every optimization step took place with a 1:1 (w:w) mixture of yellow and red cashew apples lyophilized and ground in a cryogenic mill. A Simplex-centroid design was applied for both methods, and the solvents acetone, methanol, ethanol, and petroleum ether were evaluated. After choosing the extractor solvent, a central composite design was applied to optimize the sample mass (59–201 mg) and extraction time (6–34 min). The optimum conditions for the extractor solvent were 38% acetone, 30% ethanol, and 32% petroleum ether for CE and a mixture of 44% acetone and 56% methanol for UAE. The best experimental conditions for UAE were a sonication time of 19 min and a sample mass of 153 mg, while the CE was 23 min and 136 mg. Comparing red and yellow cashews, red cashews showed a higher carotenoid content in both methodologies. The UAE methodology was ca. 21% faster, presented a more straightforward composition of extracting solution, showed an average yield of superior carotenoid content in all samples compared to CE. Therefore, UAE has demonstrated a simple, efficient, fast, low-cost adjustment methodology and a reliable alternative for other applications involving these bioactive compounds in the studied or similar matrix. 相似文献
2.
J. Chevallier A. Duarte E. Löcherbach G. Ost 《Stochastic Processes and their Applications》2019,129(1):1-27
We consider spatially extended systems of interacting nonlinear Hawkes processes modeling large systems of neurons placed in and study the associated mean field limits. As the total number of neurons tends to infinity, we prove that the evolution of a typical neuron, attached to a given spatial position, can be described by a nonlinear limit differential equation driven by a Poisson random measure. The limit process is described by a neural field equation. As a consequence, we provide a rigorous derivation of the neural field equation based on a thorough mean field analysis. 相似文献
3.
Zihua Guo Xingxing Liu Luc Molinet Zhaoyang Yin 《Journal of Differential Equations》2019,266(2-3):1698-1707
We prove norm inflation and hence ill-posedness for a class of shallow water wave equations, such as the Camassa–Holm equation, Degasperis–Procesi equation and Novikov equation etc., in the critical Sobolev space and even in the Besov space for . Our results cover both real-line and torus cases (only real-line case for Novikov), solving an open problem left in the previous works ([5], [14], [16]). 相似文献
4.
We consider a Schrödinger operator on , where V is a real-valued measurable function, and give an explicit and simple characterization of intrinsic ultracontractivity (IU) of the Schrödinger semigroup generated by L for a wide class of potentials. By making use of it, we also give new examples of potentials for which the semigroups satisfy (IU) or non-(IU). 相似文献
5.
This paper deals with the Cauchy–Dirichlet problem for the fractional Cahn–Hilliard equation. The main results consist of global (in time) existence of weak solutions, characterization of parabolic smoothing effects (implying under proper condition eventual boundedness of trajectories), and convergence of each solution to a (single) equilibrium. In particular, to prove the convergence result, a variant of the so-called ?ojasiewicz–Simon inequality is provided for the fractional Dirichlet Laplacian and (possibly) non-analytic (but ) nonlinearities. 相似文献
6.
In this paper we prove that weak solutions to the Diffusive Wave Approximation of the Shallow Water equations are locally bounded. Here, u describes the height of the water, z is a given function that represents the land elevation and f is a source term accounting for evaporation, infiltration or rainfall. 相似文献
7.
Wenyuan Xu Yan Wang Suying Li Yongbing Cheng Zanru Guo Lin Hu Mengyin Liao Jiaxi Peng Xi Chen Shaoming Yang 《应用有机金属化学》2021,35(1)
Dimethyldichlorosilane, one of the most consumed organosilicon monomers in the industry, can be prepared in a highly efficient and environmentally friendly synthesis method of disproportionating methylchlorosilanes. However, the internal mechanism of the reaction remains unclear. In this paper, the mechanism catalyzed by AlCl3/MIL‐53(Al) and AlCl3/MIL‐53(Al)@γ‐Al2O3 catalysts was calculated at B3LYP/6‐311++G(3df, 2pd) level by using the density functional theory (DFT). The results showed that although the two catalysts had similar active structures, the catalytic effects were significantly different. The Lewis acid center on the surface of γ‐Al2O3 in the core‐shell catalyst is complementary to the classic Lewis acid AlCl3 through the spatial superposition effect, which greatly improves the Lewis acid catalytic activity of AlCl3/MIL‐53(Al)@γ‐Al2O3. 相似文献
8.
In the last decade,the functionally graded carbon nanotube reinforced composites(FG-CNTRCs)have attracted considerable interest due to their excellent mechanical properties,and the structures made of FG-CNTRCs have found broad potential applications in aerospace,civil and ocean engineering,automotive industry,and smart structures.Here we review the literature regarding the mechanical analysis of bulk CNTR nanocomposites and FG-CNTRC structures,aiming to provide a clear picture of the mechanical modeling and properties of FG-CNTRCs as well as their composite structures.The review is organized as follows:(1)a brief introduction to the functionally graded materials(FGM),CNTRCs and FG-CNTRCs;(2)a literature review of the mechanical modeling methodologies and properties of bulk CNTRCs;(3)a detailed discussion on the mechanical behaviors of FG-CNTRCs;and(4)conclusions together with a suggestion of future research trends. 相似文献
9.
Vitamin K1 distribution following intravenous vitamin K1–fat emulsion administration in rats 下载免费PDF全文
Xue Xiao Yan‐Ni Mi Fa Wang Bing‐Hua Zhang Lei Cao Yong‐Xiao Cao 《Biomedical chromatography : BMC》2015,29(12):1849-1858
This study investigated vitamin K1 (VK1) distribution following intravenous vitamin K1–fat emulsion (VK1–FE) administration and compared it with that after VK1 injection. Rats were intravenously injected with VK1–FE or VK1. The organ and tissue VK1 concentrations were determined using high‐performance liquid chromatography method at 0.5, 2 and 4 h to determine distribution, equilibrium and elimination phases, respectively. In the VK1–FE group, the plasma, heart and spleen VK1 concentrations decreased over time. However, other organs like liver, lung, kidney, muscle and testis, reached peak VK1 concentrations at 2 h. In the VK1 injection group, the liver VK1 concentrations were significantly higher than those in other organs at the three time points. However, VK1 concentrations in the other organs peaked at 2 h. In addition, in VK1–FE group, the heart, spleen and lung VK1 concentrations were significantly higher than those in the VK1 injection group at the three time points, and the liver VK1 concentration was significantly higher than that in the VK1 injection group at 4 h. The VK1 amount was greatest in the liver compared with the other organs. Thus, the liver is the primary organ for VK1 distribution. The distribution of VK1 is more rapid when injected as VK1–FE than as VK1. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
10.
Metal Oxide Assisted Preparation of Core–Shell Beads with Dense Metal–Organic Framework Coatings for the Enhanced Extraction of Organic Pollutants 下载免费PDF全文
Mateo del Rio Dr. Carlos Palomino Cabello Veronica Gonzalez Dr. Fernando Maya Dr. Jose B. Parra Dr. Victor Cerdà Dr. Gemma Turnes Palomino 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(33):11770-11777
Dense and homogeneous metal–organic framework (MOF) coatings on functional bead surfaces are easily prepared by using intermediate sacrificial metal oxide coatings containing the metal precursor of the MOF. Polystyrene (PS) beads are coated with a ZnO layer to give ZnO@PS core–shell beads. The ZnO@PS beads are reactive in the presence of 2‐methylimidazole to transform part of the ZnO coating into a porous zeolitic imidazolate framework‐8 (ZIF‐8) external shell positioned above the internal ZnO precursor shell. The obtained ZIF‐8@ZnO@PS beads can be easily packed in column format for flow‐through applications, such as the solid‐phase extraction of trace priority‐listed environmental pollutants. The prepared material shows an excellent permeance to flow when packed as a column to give high enrichment factors, facile regeneration, and excellent reusability for the extraction of the pollutant bisphenol A. It also shows an outstanding performance for the simultaneous enrichment of mixtures of endocrine disrupting chemicals (bisphenol A, 4‐tert‐octylphenol and 4‐n‐nonylphenol), facilitating their analysis when present at very low levels (<1 μg L?1) in drinking waters. For the extraction of the pollutant bisphenol A, the prepared ZIF‐8@ZnO@PS beads also show a superior extraction and preconcentration capacity to that of the PS beads used as precursors and the composite materials obtained by the direct growth of ZIF‐8 on the surface of the PS beads in the absence of metal oxide intermediate coatings. 相似文献