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排序方式: 共有342条查询结果,搜索用时 15 毫秒
11.
Ivor M. do Prado Willyan M. Giufrida Víctor H. Alvarez Vladimir F. Cabral Sócrates Quispe-Condori Marleny D. A. Saldaña Lucio Cardozo-Filho 《Journal of the American Oil Chemists' Society》2011,88(8):1263-1269
New data on phase equilibria for Sacha inchi seed oil in carbon dioxide have been measured using a variable volume cell phase
equilibria system at temperatures of 303, 313 and 323 K and at pressures ranging from 4.3 to 27.7 MPa. The CO2 mole fraction varied from 0.7488 to 0.9997. At the studied concentrations, phase transitions of vapor-liquid, liquid-liquid-vapor
and liquid-liquid were observed. Sacha inchi oil contains 47% of omega-3 fatty acids, with a ratio of 0.76:1 for omega-6:omega-3,
which is good for human health. The Peng-Robinson equation of state was used to describe the experimental data. A qualitative
agreement was obtained between experimental and calculated data for the binary system CO2 and Sacha inchi seed oil. 相似文献
12.
13.
DellaGreca M Isidori M Lavorgna M Monaco P Previtera L Zarrelli A 《Journal of chemical ecology》2004,30(4):867-879
Twenty-five 9,10-dihydrophenanthrenes, four phenanthrenes, a dihydrodibenzoxepin, and a pyrene, isolated from the wetland plant Juncus acutus, were tested to detect their effects on the green alga Selenastrum capricornutum. Nine of the compounds were isolated and identified for the first time. Most of the compounds caused inhibition of algal growth. The 9,10-dihydrophenanthrenes 1, 5, 21, and 22 were the most active. 相似文献
14.
Selective hydrogenation of benzene to cyclohexene using a suspended Ru catalyst in a mechanically agitated tetraphase reactor 总被引:4,自引:0,他引:4
The reactivity on unsupported Ru based catalyst in benzene selective hydrogenation to cyclohexene has been studied. The reaction has been carried out in a tetraphase slurry reactor at 423 K, at 5 MPa, in the presence of two liquid phases: benzene and an aqueous solution of ZnSO4 0.6 mol l−1. A detailed study of the influence of the transport phenomena on the reactivity of the catalyst has been carried out. No correlation has been found between the characteristic numbers of Weeler–Weisz and of Carberry mass transport at external liquid/solid interface or into the catalyst pores for both benzene and hydrogen and the selectivity of the catalyst. The main features of the catalysts are the strong dependence between the catalysts preparation procedure and their activity and selectivity. In particular the influence of the alkaline or the earth alkaline hydroxide, employed in the precipitation of the Ru precursor, on the selectivity, has been studied. Hydrogen chemisorption measurements indicate that the amount of weakly adsorbed hydrogen depends on the nature of the base employed in the precipitation step. 相似文献
15.
Rossana Di Martino Maria Jos Sisalli Rossana Sirabella Salvatore Della Notte Domenica Borzacchiello Antonio Feliciello Lucio Annunziato Antonella Scorziello 《International journal of molecular sciences》2021,22(15)
The exact mechanism underlying selective dopaminergic neurodegeneration is not completely understood. The complex interplay among toxic alpha-synuclein aggregates, oxidative stress, altered intracellular Ca2+-homeostasis, mitochondrial dysfunction and disruption of mitochondrial integrity is considered among the pathogenic mechanisms leading to dopaminergic neuronal loss. We herein investigated the molecular mechanisms leading to mitochondrial dysfunction and its relationship with activation of the neuroinflammatory process occurring in Parkinson’s disease. To address these issues, experiments were performed in vitro and in vivo in mice carrying the human mutation of α-synuclein A53T under the prion murine promoter. In these models, the expression and activity of NCX isoforms, a family of important transporters regulating ionic homeostasis in mammalian cells working in a bidirectional way, were evaluated in neurons and glial cells. Mitochondrial function was monitored with confocal microscopy and fluorescent dyes to measure mitochondrial calcium content and mitochondrial membrane potential. Parallel experiments were performed in 4 and 16-month-old A53T-α-synuclein Tg mice to correlate the functional data obtained in vitro with mitochondrial dysfunction and neuroinflammation through biochemical analysis. The results obtained demonstrated: 1. in A53T mice mitochondrial dysfunction occurs early in midbrain and later in striatum; 2. mitochondrial dysfunction occurring in the midbrain is mediated by the impairment of NCX3 protein expression in neurons and astrocytes; 3. mitochondrial dysfunction occurring early in midbrain triggers neuroinflammation later into the striatum, thus contributing to PD progression during mice aging. 相似文献
16.
This article proposes an analytical model for evaluating the number of simultaneous communications that can be sustained by
an ad-hoc network in which the nodes are equipped with fully adaptive smart antennas. The presented mathematical framework
adopts realistic models for the antenna radiation pattern and the channel behavior, and is able to take into account the network
topology and the characteristics of the medium access control (MAC) protocol in the spatial domain. The model is employed
to investigate the impact of the spatial channel model and of the angular spread on network performance. Additionally, this
article examines the influence of the transmission policy of the control and data packets of the MAC layer on the number of
simultaneous communications. 相似文献
17.
Albanese Massimiliano Chianese Angelo Moscato Vincenzo Sansone Lucio 《Multimedia Tools and Applications》2004,24(3):253-272
The first step in a video indexing process is the segmentation of videos into meaningful parts called shots. In this paper we present a formal model of the video shot segmentation process. Starting from a mathematical characterization of the most common transition effects, a video segmentation algorithm capable to detect both abrupt and gradual transitions is proposed. The proposed algorithm is based on the computation of an arbitrary similarity measure between consecutive frames of a video. The algorithm has been tested adopting a similarity metric based on the Animate Vision theory and results have been reported. 相似文献
18.
do Lago CL da Silva HD Neves CA Brito-Neto JG da Silva JA 《Analytical chemistry》2003,75(15):3853-3858
A new microfabrication process based on a xerographic process is described. A laser printer is used to selectively deposit toner on a polyester film, which is subsequently laminated against another polyester film. The toner layer binds the two polyester films and allows the blank regions to become channels for microfluidics. These software-outlined channels are approximately 6 microm deep. Approximately twice this depth is obtained by laminating two printed films. The resulting devices were not significantly damaged after 24 h of exposure to aqueous solutions of H3PO4, NaOH, methanol, acetonitrile, or sodium dodecyl sulfate. Electric tests with an impedance analyzer and microchannels filled with KCl solution demonstrated that (1) wide channels suffer from deformation of the top and bottom walls due to the lamination of the polyester films and (2) the toner walls are somewhat porous. Although these drawbacks limit the maximum width of a channel and the minimum distance between two channels, the process is an attractive option to other expensive, laborious, and time-consuming methods for microchannels fabrication. The process has been used to implement devices for electrospray tip and capillary electrophoresis with contactless conductivity detection. 相似文献
19.
Web-based education and training provides a new paradigm for imparting knowledge; students can access the learning material anytime by operating remotely from any location. Web3D open standards, such as X3D and VRML, support Web-based delivery of Educational Virtual Environments (EVEs). EVEs have a great potential for learning and training purposes, by allowing one to circumvent physical, safety, and cost constraints. Unfortunately, EVEs often leave to the user the onus of taking the initiative both in exploring the environment and interacting with its parts. A possible solution to this problem is the exploitation of virtual humans acting as informal coaches or more formal instructors. For example, virtual humans can be employed to show and explain maintenance procedures, allowing learners to receive more practical explanations which are easier to understand. However, virtual humans are rarely used in Web3D EVEs, since the programming effort to develop and re-use them in different environments can be considerable. In this paper, we present a general architecture that allows content creators to easily integrate virtual humans into Web3D EVEs. To test the generality of our solution, we present two practical examples showing how the proposed architecture has been used in different educational contexts. 相似文献
20.
Postfailure Mechanics of Landslides: Laboratory Investigation of Flowslides in Pyroclastic Soils 总被引:2,自引:0,他引:2
Of all landslides, subaerial flowslides are the most dangerous. According to the literature, flowslides in saturated granular deposits are caused by static liquefaction induced by loss of stability. However, the catastrophic flowslides that occurred on steep slopes in Campania (southern Italy) in 1998, 1999, and 2005 were triggered by rainwater infiltration into shallow deposits of pyroclastic soils, which were initially unsaturated. Starting from the experience collected during the investigations of some of these landslides, the writers consider flowslide evolution as a result of a mechanical chain process characterized by saturation increase due to rainwater infiltration, mechanical degradation, volumetric collapse, and static liquefaction, culminating in complete fluidization of the soil. In the paper this chain process is investigated through wetting tests both in suction controlled triaxial apparatuses and in a well-equipped small scale slope model. 相似文献