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排序方式: 共有182条查询结果,搜索用时 15 毫秒
101.
Mohammad Shoeb Ahmed Paul Munroe Zhong-Tao Jiang Xiaoli Zhao William Rickard Zhi-feng Zhou Lawrence Kwok Yan Li Zonghan Xie 《Corrosion Science》2011,53(11):3678-3687
Nanocomposite TiSiN coatings were deposited on tool steels. Detailed mechanisms that govern the corrosion of these coated steels were revealed, following immersion tests in a 70% nitric acid solution. Pitting originated preferentially from coating defect sites and expanded with increasing immersion time. Both Young’s modulus and hardness measured by nanoindentation decreased as the corrosion damage intensified. A thin oxide layer formed from the thermal annealing of the as-deposited samples at 900 °C was found to be effective against corrosive attack. In addition, compressive residual stress was noted to suppress the propagation of corrosion-induced cracks. The role of residual stress in controlling the corrosion resistance of these ceramic-coated steels is clarified by finite element analysis. 相似文献
102.
The chemical compositions of 32 cultivars of two edible aroid species (Colocasia esculenta var antiquorum and Xanthosoma sagittifolium) were determined. Mean values obtained for both species in g kg?1 dry weight were: crude protein 37.5–73.6, total fat 0.9–8.7, ash 28.7–77.7, crude fibre 4.3–42.0, total sugars 5.9–42.5 and starch 509.1–705.7. The mam sugars identified by HPLC were fructose, glucose, sucrose and maltose. The amino acids with the highest concentrations were aspartic acid, glutamic acid and arginine. A significant reduction in starch content (to 39.8–47.4 g kg?1) and increase in total sugars content (to 8.0–11.6 g kg?1) occurred during the storage of cormels for two weeks under tropical ambient conditions (24–29°C; 86–98% RH). No significant differences (P> 0.05) between fresh and stored cormels were found in crude protein and amino acid contents. 相似文献
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105.
Leukemia inhibitory factor (LIF) can regulate the survival and differentiation of certain neurons and glial cells in culture. To determine the role of this cytokine in the central nervous system in vivo, we examined the brains of young and adult mice in which the LIF gene was disrupted. Immunohistochemical staining of neurons for choline acetyltransferase, tyrosine hydroxylase, serotonin, parvalbumin, calbindin, neuropeptide Y, vasoactive intestinal polypeptide, and calcitonin gene-related peptide revealed no significant differences between null mutant and wild-type (WT) brains. In contrast, analysis of glial phenotypes demonstrated striking deficits in the LIF-knockout brain. Staining with several anti-glial fibrillary acidic protein (GFAP) antibodies showed that the number of GFAP-positive cells in various regions of the hippocampus in the female mutant is much lower than in the WT. The null male hippocampus also displays a significant, though less marked deficit. The number of astrocytes in the mutant hippocampus, as determined by S-100 staining, is not, however, significantly different from WT. In addition, quantification of immunohistochemical staining of female, but not male, mutants reveals a significant deficit in myelin basic protein content in three brain regions, suggesting alterations in oligodendrocytes as well. Thus, while overall brain histology appears normal, the absence of LIF in vivo leads to specific, sexually dimorphic alterations in glial phenotype. 相似文献
106.
This paper summarises information on the structure and function of dune slacks as discrete ecosystems within the Alexandria coastal dunefield. A typical slack, with a total area of 1900 m2 and floor area of 8833 m2, harbours four dominant species of pioneer plants in a succession spanning 5 years, corresponding to the interval between a section of slack floor being uncovered by a retreating dune and smothered by an advancing dune. Vegetation biomass totals 221.1 g m−2 and detritus mass 40.1 g m−2, with 31% and 3% above ground, respectively. Annual plant production is estimated at 190 g m−2 using a combination of theoretical calculations and vegetative growth estimates. Animal biomass has been quantified for interstitial meiofauna at 1.0 g m−2 and all arthropod and vertebrate macrofauna at 0.2 g m−2. Based on estimated decomposition coefficients of 0.5 year−1 and theoretical consumption estimates for the fauna, 14% of plant production is grazed directly (93% by plant parasitic nematodes, 7% by macrofauna) and 86% enters the detritus pool. Of the latter, 2% is consumed by macrofauna detritivores, 63% is decomposed by the interstitial fauna and 35% accumulates to add to the detritus pool. Vegetation succession and production in the slack thus results in a net build-up of organic matter in the sand. This is finally decomposed when the slack is smothered by an advancing dune ridge, thus maintaining a long term equilibrium level of soil organics. These slacks require minimal management as long as free dune movement and limited human access are maintained. 相似文献
107.
Lundstedt-Enkel K Bjerselius R Asplund L Nylund K Liu Y Södervall M 《Environmental science & technology》2010,44(23):9018-9023
Baltic Sea herring (Clupea harengus) is a pelagic, zoo-planktivorous fish and young (2-5 years old) individuals of this species are sampled annually in the Swedish marine monitoring program. This study determined concentrations of organochlorines (OCs) and brominated flame retardants (BFRs) in dorsal muscle from herring (n = 60) of varying age (2-13 years), weight (25-200 g), and body length (16-29 cm) caught at three locations in the Swedish part of the Baltic Proper. In order to ensure that the fish biology was as varied as possible, though still similar from all sampling sites, the fish to be chemically analyzed were selected from a large number of fish with determined biology using Multivariate Design. In statistical evaluation of the data, univariate and multivariate data analysis techniques, e.g. principal components analysis (PCA), partial least-squares regression (PLS), and orthogonal PLS (OPLS), were used. The results showed that the fish are exposed to a cocktail of contaminants and levels are presented. Significant OPLS models were found for all biological variables versus concentrations of OCs and BFRs, showing that fish biology covaries with fish contaminant concentrations. Correlation coefficients were as high as 0.98 for e.g. βHCH concentration (wet weight) versus the lipid content. Lastly, the OC concentrations in herring muscle were modeled against the BFR concentrations to determine whether concentrations of either could be used to predict the other. It was found that OPLS models allowed BFR concentrations to be predicted from OC concentrations with high, but varying, accuracy (R(2)Ys between 0.93 to 0.75). Thus, fish biology and contaminant concentrations are interwoven, and fish biological parameters can be used to calculate (predict) contaminant concentrations. It is also possible to predict the BFR concentrations in an individual fish from its concentrations of OCs with very high accuracy. 相似文献
108.
Niklas Lorén Jun Niimi Evelina Höglund Rickard Albin Elisabet Rytter Karin Bjerre Tim Nielsen 《Journal of food science》2023,88(3):885-900
In many parts of the world, sodium consumption is higher than recommended levels, representing one of the most important food-related health challenges and leading to considerable economical costs for society. Therefore, there is a need to find technical solutions for sodium reduction that can be implemented by food producers and within food services. The aims of this review are to discuss the barriers related to sodium reduction and to highlight a variety of technical solutions. The barriers relate to consumer perception, microbiology, processing, and physicochemistry. Existing technical solutions include inhomogeneous salt distribution, coated salt particles, changing particle sizes and forms, surface coating, multisensory combinations, sodium replacements, double emulsions, adapted serum release by microstructure design, and adapted brittleness by microstructure design. These solutions, their implementation and the associated challenges, and applicable product categories are described. Some of these solutions are ready for use or are in their early development stages. Many solutions are promising, but in most cases, some form of adaptation or optimization is needed before application in specific products, and care must always be taken to ensure food safety. For instance, further research and innovation are required in the dynamic evolution of saltiness perception, consumer acceptance, the binding and migration of sodium, juiciness, microbiological safety, and the timing of salt addition during processing. Once implemented, these solutions will undoubtedly support food producers and food services in reducing sodium content and extend the application of the solutions to different foods. 相似文献
109.
Rickard Brüel-Gabrielsson Vignesh Ganapathi-Subramanian Primoz Skraba Leonidas J. Guibas 《Computer Graphics Forum》2020,39(5):197-207
We present an approach to incorporate topological priors in the reconstruction of a surface from a point scan. We base the reconstruction on basis functions which are optimized to provide a good fit to the point scan while satisfying predefined topological constraints. We optimize the parameters of a model to obtain a likelihood function over the reconstruction domain. The topological constraints are captured by persistence diagrams which are incorporated within the optimization algorithm to promote the correct topology. The result is a novel topology-aware technique which can (i) weed out topological noise from point scans, and (ii) capture certain nuanced properties of the underlying shape which could otherwise be lost while performing surface reconstruction. We show results reconstructing shapes with multiple potential topologies, compare to other classical surface construction techniques, and show the completion of real scan data. 相似文献
110.