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911.
912.
The amounts of substances migrating from plastics into foodstuffs with high fat contents are in most cases higher than in foodstuffs with water contents. This increase in migration commonly is due to the higher solubility of the migrating organic compounds in fat compared to water. The increase in migration is not necessarily due to an increase in the substance's diffusion coefficient due to interactions between the fat and the plastic as is often assumed. Ethanol is a good simulant for fatty foods because it has little interaction with many plastics, e.g. polyolefins, migrants are readily soluble in it, and because it is easy to work with analytically. The utilizable limits of ethanol and ethanol/water mixtures as food simulants are developed from the physical background of diffusion. The use of ethanol and ethanol/water mixtures is supported by published experimental migration results. 相似文献
913.
WATER ABSORPTION and SWELLING IN DRY BEAN SEEDS 总被引:1,自引:0,他引:1
914.
Conditioned eyeblink responses are presumably learned in the cerebellum and relayed to motoneurons by way of the red nucleus. Projections from the red nucleus to cerebellar cortex (Larsell's lobule HVI) could be important for shaping temporally adaptive features of the conditioned response. Rabbits that had pipettes containing wheat germ agglutinated horseradish peroxidase (WGA-HRP) implanted unilaterally into HVI showed retrograde labeling of neurons within subregions of the contralateral red nucleus implicated in eyeblink conditioning by lesioning and recording studies. Retrogradely labeled neurons were also observed in the pontine nuclei, inferior olive, and spinal trigeminal nucleus pars oralis. Projections to HVI provide a possible neural substrate for implementing time-derivative computational models of learning in the cerebellum. Time-derivative models are capable of describing the timing and topography of conditioned responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
915.
Partial eigenvalue decomposition of large images using spatialtemporal adaptive method 总被引:1,自引:0,他引:1
Finding eigenvectors of a sequence of real images has usually been considered to require too much computation to be practical. Our spatial temporal adaptive (STA) method reduces the computational complexity of the approximate partial eigenvalue decomposition based on image encoding. Spatial temporal encoding is used to reduce storage and computation, and then, singular value decomposition (SVD) is applied. After the adaptive discrete cosine transform (DCT) encoding, blocks that are similar in consecutive images are consolidated. The computational economy of our method was verified by tests on different large sets of images. The results show that this method is 6 to 10 times faster than the traditional SVD method for several kinds of real images. The economy of this algorithm increases with increasing correlation within the image and with increasing correlation between consecutive images within a set. This algorithm is useful for pattern recognition using eigenvectors, which is a research field that has been active recently. 相似文献
916.
Lipase-Catalyzed Interesterification of Triglycerides in a Solvent-Free Process I: Analytics and Kinetics of the Interesterification The interesterification of lipids catalyzed by immobilized lipases is an interesting substitute to the chemical interesterification. Studies using an industrial manufactured biocatalyst in a solvent-free process were performed. The kinetics of the interesterification were examined as a function of temperature and water content of the reaction system. The reaction rate of the interesterification can be described with reversible first order reaction kinetics. A part of the triglycerides of the substrate is hydrolyzed by a lipasecatalyzed lipolysis. Hydrolysis products are 1,2(2,3) and 1,3-diglycerides. This shows that an unspecific interesterification is catalyzed if the residence time is extended. 相似文献
917.
In-vitro studies were conducted to characterize the transdermal iontophoretic delivery of insulin, thus avoiding potential complications from various biological variations, which may be encountered during in-vivo studies. The proteolytic degradation of insulin in skin homogenates and degradation under the experimental conditions used was investigated. Appropriate adjuvants were incorporated to minimize the potential degradation problems of insulin. 125I-Insulin was observed to penetrate into and accumulate in the skin during the iontophoresis period. It was then released gradually from this depot, as a mixture of intact and 125-I labelled fragments, into the receptor medium. Drug desorption studies supported the theory of skin depot or reservoir formation. It was found that an electric field could be used to facilitate the desorption of drug from the depot. The post-application flux of insulin (or its fragments) from the skin depot formed during iontophoresis was monitored to study the factors affecting the iontophoretic delivery of insulin. Stripping and delipidization of the skin were noted to increase the skin permeation rate of insulin. The cumulative radioactivity permeated and accumulated in the skin was higher at pH 3.6 than at pH 7.4. The iontophoresis-facilitated transdermal delivery was observed to increase with increasing duration of current application and increasing donor concentration of insulin. Modulation of drug delivery by multiple applications was also found to be feasible. 相似文献
918.
Previous investigations have suggested the use of multiple communicating processors for executing logic programs. However, this strategy lacks efficiency due to competition for memory and communication bandwidth, and this is a problem that has been largely neglected. In this paper we propose a realistic model for executing logic programs with low overhead on multiple processors. Our proposal does not involve shared memory or copying computation state between processors. The model organises computations over the nondeterministic proof tree so that different processors explore unique deterministic computation paths independently, in order to exploit the “OR-parallelism” present in a program. We discuss the advantages of this approach over previous ones, and suggest control strategies for making it effective in practice. 相似文献
919.
A new approach to digital current differential protection is described which provides the capabilities of conventional pilot wire differential protection while using the limited data transfer capabilities of a digital data voice-frequency grade communications channel. This approach compares polyphase polarised current measurements taken at the feeder's terminals to detect faults and can trip in under two power system cycles. The algorithms decouple the measurements from the power system frequency and its waveform, and thereby have a high inherent tolerance to the complications introduced by communication channel delays and their fluctuations. For this project, the communications requirements have been limited to a full duplex 2400 bits/sec system suitable for operation over a voice-frequency grade channel 相似文献
920.
We demonstrate highly efficient all-optical conversion from 1.5 μm to 1.3 μm using a novel nonlinear optical loop mirror that compensates for walk-off. We make the fiber loop by splicing alternating segments of standard single-mode and dispersion-shifted fibers and choose their lengths such that the walk-off of the 1.3 μm and 1.5 μm pulses in one segment is completely reversed in the adjacent segment. We also show that the width of the converted pulses can be tailored by this scheme 相似文献