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排序方式: 共有254条查询结果,搜索用时 78 毫秒
91.
The Effects of Process-Induced Pectin Changes on the Viscosity of Carrot and Tomato Sera 总被引:1,自引:0,他引:1
Katlijn R. N. Moelants Ruben P. Jolie Stijn K. J. Palmers Ruth Cardinaels Stefanie Christiaens Sandy Van Buggenhout Ann M. Van Loey Paula Moldenaers Marc E. Hendrickx 《Food and Bioprocess Technology》2013,6(10):2870-2883
The influence of process-induced pectin changes on the kinematic viscosity of the serum phases of carrot and tomato purées was investigated in this study. Variations in the amount of pectin present in the serum phase and pectin’s fine structure were induced by subjecting carrot and tomato to different thermal treatments, i.e. a mild and a strong heat treatment, followed by blending and high-pressure homogenisation at different pressure levels (0, 20 and 100 MPa). Changes in pectin structure were monitored by determination of the degree of methoxylation, analysing the molar mass distribution and immuno-dot blotting using anti-pectin antibodies. Characterisation of serum pectins revealed that a strong thermal treatment caused pectin thermosolubilisation and depolymerisation, especially in carrot sera, and high-pressure homogenisation provoked predominantly mechanical pectin solubilisation in carrot sera and pectin depolymerisation in tomato sera. It was observed that the kinematic viscosity of carrot sera was mainly affected by the amount of solubilised pectin, whereas in tomato sera, the kinematic viscosity could mainly be explained in terms of polysaccharide chain length. The degree of methoxylation of pectin, which has a broader distribution in tomato sera than in carrot sera, seemed to have a less pronounced role in determining the kinematic viscosity. In general, it could be concluded that serum viscosity is mainly determined by the amount and size of the solubilised pectin. The influence of serum viscosity on the rheology of the studied purées was limited as the rheology of this type of system is largely determined by the particle properties of the dispersed phase. 相似文献
92.
Game developers are often faced with very demanding requirements on huge numbers of agents moving naturally through increasingly large and detailed virtual worlds. With the advent of multi‐core architectures, new approaches to accelerate expensive pathfinding operations are worth being investigated. Traditional single‐processor pathfinding strategies, such as A* and its derivatives, have been long praised for their flexibility. We implemented several parallel versions of such algorithms to analyze their intrinsic behavior, concluding that they have a large overhead, yield far from optimal paths, do not scale up to many cores or are cache unfriendly. In this article, we propose Parallel Ripple Search, a novel parallel pathfinding algorithm that largely solves these limitations. It utilizes a high‐level graph to assign local search areas to CPU cores at “equidistant” intervals. These cores then use A* flooding behavior to expand towards each other, yielding good “guesstimate points” at border touch on. The process does not rely on expensive parallel programming synchronization locks but instead relies on the opportunistic use of node collisions among cooperating cores, exploiting the multi‐core's shared memory architecture. As a result, all cores effectively run at full speed until enough way‐points are found. We show that this approach is a fast, practical and scalable solution and that it flexibly handles dynamic obstacles in a natural way. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
93.
Development of species sensitivity distributions for wildlife using interspecies toxicity correlation models 总被引:2,自引:0,他引:2
Species sensitivity distributions (SSD) are probability distributions of chemical toxicity of multiple species and have had limited application in wildlife risk assessment because of relatively small data sets of wildlife toxicity values. Interspecies correlation estimation (ICE) models predict the acute toxicity to untested taxa from known toxicity of a single surrogate species. ICE models were used to predict toxicity values to wildlife species and generate SSDs for 23 chemicals using four avian surrogates. The hazard levels associated with the fifth percentile of the distribution (HD5) were compared for ICE SSDs and independent SSDs created with measured data. SSDs were composed of either avian only or avian and mammalian taxa. ICE HD5s were within 5-fold of 90% of measured HD5s and were generally higher than measured HD5s. The first percentile of the distribution (HD1) and the fifth percentile of the lower confidence limit (HDL) of ICE SSDs produced values that were not significantly different from measured HD5s. Using a bird surrogate to predicttoxicity to birds and the Norway rat to predict toxicity to mammals improved some estimates of ICE HD5s compared with those generated using only bird surrogates. These results indicate that ICE models can be used to generate SSDs comparable to those derived from measured wildlife toxicity data and provide robust estimates of the HD5. 相似文献
94.
Sandy Van Buggenhout Tara Grauwet Ann Van Loey Marc Hendrickx 《European Food Research and Technology》2008,226(5):1145-1154
Strawberry samples of two varieties (Camarosa and Elsanta) were dehydrated using different osmotic solutions (60% glucose,
fructose, sucrose and raftilose) and subsequently frozen by rapid and high-pressure shift freezing (HPSF). The effect of pectinmethylesterase
(PME) and calcium (Ca++) added to the osmotic solutions on several compositional parameters and the textural/structural quality of dehydrated and
osmodehydrofrozen-then-thawed samples was studied. Due to the presence of PME and Ca++ in the osmotic solutions, weight reduction upon dehydration was slightly decreased, which was correlated to a small positive
effect on the net uptake of sugars and depression of the initial freezing point. Except for the Camarosa samples treated with
sucrose, PME and Ca++ in osmotic sugar solutions positively affected the relative hardness of dehydrated fruits, which was ascribed to the effect
of PME and Ca++ on the cell wall strength of the tissue. No cell wall damage and tissue particle alterations were observed upon dehydration.
The effect of osmotic dehydration (OD) using different sugar solutions without PME and Ca++ on the texture and structure of frozen-then-thawed samples was limited and sometimes negative. The added PME and Ca++ however positively influenced the volume and shape of the thawed samples, which could be related to slightly higher relative
hardness values and, for the Elsanta strawberry fruits, also to the reduced (up to 81%) drip loss upon thawing. Upon freezing
the dehydrated fruits, no cell wall disruption was observed. Tissue distortion caused by freezing and indicated by a decrease
in particle size, convexity and roundness, was compensated by the use of PME and Ca++ during OD. 相似文献
95.
Dyer SD Versteeg DJ Belanger SE Chaney JG Raimondo S Barron MG 《Environmental science & technology》2008,42(8):3076-3083
Species sensitivity distributions (SSD) require a large number of measured toxicity values to define a hazard level protective of multiple species. This investigation comprehensively evaluated the accuracy of SSDs generated from toxicity values predicted from interspecies correlation estimation (ICE) models. ICE models are log-log correlations of multiple chemical toxicity values for a pair of species that allow the toxicity of multiple species to be predicted from a single measured acute toxicity value for a surrogate species. ICE SSDs were generated using four surrogate species (fathead minnow, Pimephales promelas; rainbow trout, Oncorhynchus mykiss; sheepshead minnow, Cyprinodon varigatus; and water flea, Daphnia magna). ICE-based hazard concentrations (HC5s) from the 5th percentile of the log-logistic distribution of toxicity values were compared to HC5s determined from the acute toxicity of 55 chemicals from the United States Environmental Protection Agency Ambient Water Quality Criteria (AWQC). Measured fish and invertebrate acute toxicity data and HC5s from the AWQC data sets were compared to ICE-based HC5s. Surrogate species choice was found to be an important consideration in developing predictive HC5s. These results illustrated that fish predict fish betterthan invertebrates and D. magna predicted invertebrates better than most fish. For example, a mixed model of predicted fish and invertebrates from fathead minnow and D. magna as surrogate species provided predictive relationships with an average factor of 3.0 (+/- 6.7) over 7 orders of toxic magnitude and several chemical classes (HC5(predicted)/HC5(measured)). The application of ICE models is recommended as a valid approach for generating SSDs and hazard concentrations for chemicals with limited toxicity data. 相似文献
96.
Carole Tanios Sandy Bsaibes Cédric Gennequin Madona Labaki Fabrice Cazier Sylvain Billet Haingomalala Lucette Tidahy Bilal Nsouli Antoine Aboukaïs Edmond Abi-Aad 《International Journal of Hydrogen Energy》2017,42(17):12818-12828
The catalytic performance of the Ni, Co, Mg, and Al mixed-oxide solids, synthesized via hydrotalcite route, was investigated towards the dry reforming of methane for hydrogen production. The hydrotalcite structure was successfully obtained upon the synthesis. After calcination at 800 °C under an air flow, this structure was completely decomposed and the resulting oxides (CoxNiyMgzAl2800, x and y = 0; 1; 2; 3; 4, z = 2; 4, x + y + z = 6, x, y, and z are the molar ratios) were used as catalysts and were characterized using X-ray diffraction and Temperature-Programmed Reduction. The dry reforming of methane was carried out using a mixture of CH4:CO2 (1:1) after 2 h of reduction under an H2 flow at 800 °C. Co2Ni2Mg2Al2800 showed the highest catalytic activity in the studied series, ascribable to an interaction between Ni and Co, which is optimal for such Co/Ni ratio. The post-reaction characterization of the catalytic samples by X-ray diffraction and Differential Scanning Calorimetry evidenced a better resistance towards carbon deposition for the catalysts where Co molar ratio is higher than Ni. 相似文献
97.
Wills Thomas Ashby; Sandy James M.; Yaeger Alison M. 《Canadian Metallurgical Quarterly》2002,111(1):3
The authors tested predictions, derived from a self-regulation model, about variables moderating the relationship between level of substance use (tobacco, alcohol, and marijuana) and problems associated with use. Data were from two independent studies of adolescents, with mean ages of 15.4 and 15.5 years (Ns=1,699 and 1,225). Factor analysis indicated correlated dimensions of control problems and conduct problems. Protective moderation was found for variables indexing good self-control; risk-enhancing moderation was found for variables indexing poor self-control. These effects were generally independent of deviance-prone attitudes and externalizing symptomatology. Multiple-group structural modeling indicated moderation occurred for paths from life stress and coping motives and for paths from level to control and conduct problems. Moderation effects were also found for parental variables, peer variables, and academic competence. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
98.
Multiprocessing can be cost-effective when a general-purpose system is adaptable to specific uses. 相似文献
99.
Burnstein Alvin G.; Schoenfeld Lawrence S.; Loucks Sandra; Stedman James M.; Costello Raymond M. 《Canadian Metallurgical Quarterly》1981,12(5):596
26 highly-rated psychology internship applicants were surveyed to determine their ranking of 14 potential factors influencing their choice of internship. Geographical site was important, as were various program variables. Reputation, amount of supervision, work load, and stipend level were not strikingly important. Implications for recruitment are discussed. (1 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
100.
Madden T Fernandez P Jemian P Narayanan S Sandy AR Sikorski M Sprung M Weizeorick J 《The Review of scientific instruments》2011,82(7):075109
We present a data acquisition system to perform on-the-fly background subtraction and lower-level discrimination compression of streaming x-ray photon correlation spectroscopy data from a fast charge-coupled device (CCD) area detector. The system is built using a commercial frame grabber with an on-board field-programmable gate array. The system is capable of continuously processing at least 60 CCD frames per second each consisting of 1024 × 1024 16-bit pixels with ? 15,000 photon hits per frame at a maximum compression factor of ≈95%. 相似文献