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排序方式: 共有117条查询结果,搜索用时 15 毫秒
1.
Age-related macular degeneration (AMD) is the major reason for blindness in the industrialized world with limited treatment options. Important pathogenic pathways in AMD include oxidative stress and vascular endothelial growth factor (VEGF) secretion. Due to their bioactivities, fucoidans have recently been suggested as potential therapeutics. This review gives an overview of the recent developments in this field. Recent studies have characterized several fucoidans from different species, with different molecular characteristics and different extraction methods, in regard to their ability to reduce oxidative stress and inhibit VEGF in AMD-relevant in vitro systems. As shown in these studies, fucoidans exhibit a species dependency in their bioactivity. Additionally, molecular properties such as molecular weight and fucose content are important issues. Fucoidans from Saccharina latissima and Laminaria hyperborea were identified as the most promising candidates for further development. Further research is warranted to establish fucoidans as potential therapeutics for AMD.  相似文献   
2.
Evolving multimodal mobility needs influences established human–product relationships and requires a deeper insight into color preferences for car interiors. Hence, a study was conducted in which 204 members of a web contest created 1,265 designs. After a peer‐evaluation process, 53 most‐appreciated and 34 least‐preferred interior color compositions were identified and compared to identify patterns in color choices. Besides, visual lightweight design by layering of large interior components such as the seat, a modest use of color and patterns accompanied by repetition and the framing of the entire interior to create a feeling of spaciousness were found. Additionally, differences in the type of color between most and least favored color designs were found. Brown and beige occur more frequently among the top‐ than the worst‐rated designs. Larger surfaces are favored in lighter hues and smaller components in darker hues.  相似文献   
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A discrete Laplace‐Beltrami operator is called perfect if it possesses all the important properties of its smooth counterpart. It is known which triangle meshes admit perfect Laplace operators and how to fix any other mesh by changing the combinatorics. We extend the characterization of meshes that admit perfect Laplacians to general polygon meshes. More importantly, we provide an algorithm that computes a perfect Laplace operator for any polygon mesh without changing the combinatorics, although, possibly changing the embedding. We evaluate this algorithm and demonstrate it at applications.  相似文献   
5.
The addition of aluminum oxide (Al2O3) as a sintering aid to yttria-stabilized zirconia (YSZ) reduces the required densification temperature. Sintering aids are incorporated using a number of processes which can lead to ambiguity when determining the effect of the sintering aid on the densification mechanism. In this study, a novel method for sintering aid addition, Particle Atomic Layer Deposition (ALD), was used to deposit an amorphous Al2O3 thin film on YSZ particles. Transmission electron microscopy confirmed the deposition of conformal Al2O3 thin films on the surface of the YSZ particles. The addition of Al2O3 to YSZ reduced the temperature at which densification began by ~75°C, and 2.2 wt% Al2O3 addition resulted in a minimum activation energy for the intermediate stage of densification. This concentration is well in excess of the solubility limit of Al2O3 in YSZ, showing that Al2O3 does not enhance the densification of YSZ solely by dissolving into the YSZ lattice and activating volume diffusion. The addition of 0.7 wt% Al2O3 with one Particle ALD cycle enhanced the ionic conductivity of YSZ by 23% after sintering at 1350°C for 2 hours, demonstrating that dense parts with high oxygen ion conductivities can be produced after sintering at reduced temperatures. One Particle ALD cycle is a fast, easily scaled-up process that eliminates the use of solvents and has substantial cost/performance advantages over conventional processing.  相似文献   
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Monoculture farming systems have had serious environmental impacts such as loss of biodiversity and pollinator decline. The authors explain how temperate agroforestry systems show potential in being able to deliver multiple environmental benefits.  相似文献   
8.
The effect of κ-carrageenan concentration (0-7.5 g kg−1) on the rheology, microstructure, texture and oxidative stability of water-in-oil (W/O) spreads (600 g fat kg−1 emulsion) was examined over 60 days storage time. Results showed that increasing the κ-carrageenan concentration to 7.5 g kg−1 significantly increased the viscosity of the aqueous phase (to 42.7 mPa s at 60 °C) resulting in gelation of the aqueous phase on cooling. The microstructure of the spreads was disrupted by higher levels of κ-carrageenan, resulting in a less homogeneous distribution of the aqueous phase. Melt temperature (where tan δ > 1) decreased significantly from 62 to 56.2 °C with increasing κ-carrageenan concentration from 0 to 7.5 g kg−1. The firmness and the G′ at 6 °C for all samples were significantly increased after 60 days storage with only small effects due to κ-carrageenan levels. Oxidation of the fat phase was evident by the significant increases in peroxide values of all spreads on storage, with κ-carrageenan exhibiting no antioxidant behaviour. While increased κ-carrageenan levels modified the microstructure of W/O spreads in terms of the droplet size of the aqueous phase and its distribution few changes were evident in the continuous fat phase.  相似文献   
9.
Within this paper, we present a novel, straightforward progressive encoding scheme for general triangle soups, which is particularly well‐suited for mobile and Web‐based environments due to its minimal requirements on the client's hardware and software. Our rapid encoding method uses a hierarchy of quantization to effectively reorder the original primitive data into several nested levels of detail. The resulting stateless buffer can progressively be transferred as‐is to the GPU, where clustering is efficiently performed in parallel during rendering. We combine our approach with a crack‐free mesh partitioning scheme to obtain a straightforward method for fast streaming and basic view‐dependent LOD control.  相似文献   
10.
PWM technique with partially constant modulating waves   总被引:1,自引:0,他引:1  
Contents In this paper the waveform quality and overmodulation region voltage-gain characteristic of pulsewidth-modulation (PWM) method with partially constant modulating waves are investigated. Thus the number of switchings in the three-phase inverter diminishes by 33 as compared to the classical methods. The PWM version proposed, in which during π/3 intervals only two switchings of the inverter semiconductor devices are performed, can also be matched much better to the methods for accomplishing the switchings of these devices according to the ZVS principle.
Ubersicht Im vorliegenden Aufsatz wird die Qualit?t der Wellenformen sowie die Charakteristik des Gewinns an Spannung für den Bereich der Supramodulation im Falle der Pulsbreitenmodulationstechnik (PWM) mit partiell konstanten Modulationssignalen studiert. Auf diese Weise wird die Kommutationsanzahl in einem Dreiphasen-Wechselrichter um 33 verringert im Vergleich zur klassischen PWM-Methode. Die vorgesch lagene PWM-Variante, wo in den Winkelbereichen von π/3 nur zwei Kommutationen der Halbleitervorrichtungen im Wechselrichter durchgeführt werden, kann besser an die Kommutationsmethoden dieser Vorrichtungen nach dem ZVS-Prinzip angepasst werden.


Received: 30 June 1999  相似文献   
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