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51.
Uptake of blood triglyceride by various tissues 总被引:3,自引:0,他引:3
Triglycerides are transported in the blood in chylomicrons and very low density lipoproteins. Electron microscopic studies
indicate that these particles, which range in diameter from 0.03–0.6 μ, cannot cross the capillary endothelium in most tissues.
There is now considerable evidence that the triglycerides are hydrolyzed to free fatty acids (FFA) during uptake and that
this process is catalyzed by lipoprotein lipase. The enzyme is found in nearly all tissues that utilize circulating triglyceride,
and the level of activity, in individual tissues, varies with nutritional and physiological states that affect triglyceride
uptake, such as fasting, diabetes and pregnancy. Studies in perfused adipose tissue with doubly labeled chylomicrons showed
that hydrolysis occurs outside of the blood stream. Two-thirds of the fatty acids are incorporated into tissue triglyceride
and the rest are release as FFA, with glycerol, to the blood. Infusion of heparin causes immediate release of lipoprotein
lipase activity to the blood and decreases the amount of chylomicron-triglyceride hydrolyzed by the tissue. Electron microscopic
cytochemical studies showed that hydrolysis of blood glycerides by lipoprotein lipase in adipose tissue occurs within the
capillary endothelial cells and in the subendothelial space near the pericytes, but not in the capillary lumen or near the
fat cells. The results indicate that the fatty acids of chylomicrons cross the capillary endothelium as glycerides and FFA,
within a membrane-bounded system, and cross the extravascular space to the fat cells as FFA.
Presented at the AOCS Meeting, Atlantic City, October 1971. 相似文献
52.
Stress Analysis of Elastic-Plastic Contact Damage in Ceramic Coatings on Metal Substrates 总被引:1,自引:0,他引:1
Anthony C. Fischer-Cripps † Brian R. Lawn Antonia Pajares ‡ Lanhua Wei § 《Journal of the American Ceramic Society》1996,79(10):2619-2625
An elastic-plastic analysis of damage in ceramic coatings on metal substrates from contacts with spherical indenters is made using finite element modeling. Computations are carried out specifically for plasma-sprayed alumina:titania on a soft steel. The algorithm assumes an elastic sphere with frictionless contact on a flat elastic-plastic layered specimen, and incrementally evaluates the expanding contact field as a function of applied load. Two key aspects of the contact field are examined: (i) the indentation stress-strain curve; (ii) the damage zone geometry. Composite coating/substrate indentation stress-strain curves are computed for two coating thicknesses, using input material parameters from iterative fits to data from control tests on free-standing coating and substrate materials. Contours of principal shear stresses, most notably those contours corresponding to yield zone boundaries in both the softer substrate and the harder coating, are mapped out in the fully plastic region. Corresponding distributions of tensile stresses are also mapped out, and are shown to correlate with the locations of transverse fractures in the coating. General implications concerning material and geometrical design of ceramic-based layer structures are discussed. 相似文献
53.
Anthony Walker Matthew Driller Christos Argus Julie Cooke Ben Rattray 《Ergonomics》2014,57(4):612-621
Currently, there is no enforcement of physical standards within Australian fire services post-recruitment, possibly leading to inappropriate fitness and body composition. This study evaluated the impacts of ageing on physical standards of Australian firefighters. Seventy-three firefighters from three different 10-year age groups [25–34 years (n = 27), 35–44 years (n = 27), 45–54 years (n = 19)] volunteered for physical testing using dual-energy X-ray analysis and existing fitness tests used for recruitment by an Australian fire service. Older (45–54 years) participants demonstrated significantly poorer physical standards compared with younger participants including cardiovascular fitness (p < 0.05), strength (p = 0.001) and simulated operational power testing tasks (p < 0.001). Age-related body composition changes were also observed independent of body mass index. Minimum recruitment standards and fitness programs need to account for age-related declines in physical capabilities to ensure that the minimum standard is maintained regardless of age.
Practitioner Summary: Using dual-energy X-ray analysis and established fitness testing protocols, this study aimed to gain an appreciation of the current standards of body composition and fitness of Australian firefighters and the effects of ageing on their physical abilities post-recruitment. The study demonstrated a significant decline in physical standards due to age. 相似文献
54.
Changxin Liu Jinliang Ding Anthony J. Toprac Tianyou Chai 《Knowledge and Information Systems》2014,41(2):401-421
A data-based adaptive online prediction model is proposed for plant-wide production indices based on support vector regression, a general method which we customized specifically to model very large data sets that are generated dynamically and periodically. The proposed model can update its parameters online according to the statistical properties of the training samples. Further, in order to improve the prediction precision, each sample is weighted with a dynamic penalty factor that considers the effect of each sample on the prediction model accuracy. Moreover, a customized procedure is introduced to handle large training sets. After having been convincingly evaluated on benchmark data, effectiveness and performance of our approach for plant-wide production indices is demonstrated using industrial data from an operating ore dressing plant over a range of scale in training data set size. The higher accuracy and shorter computation times than existing methods suggest that it may prove advantageous in actual application to dynamic production processes. 相似文献
55.
Dov Katz Arun Venkatraman Moslem Kazemi J. Andrew Bagnell Anthony Stentz 《Autonomous Robots》2014,37(4):369-382
Autonomous manipulation in unstructured environments will enable a large variety of exciting and important applications. Despite its promise, autonomous manipulation remains largely unsolved. Even the most rudimentary manipulation task—such as removing objects from a pile—remains challenging for robots. We identify three major challenges that must be addressed to enable autonomous manipulation: object segmentation, action selection, and motion generation. These challenges become more pronounced when unknown man-made or natural objects are cluttered together in a pile. We present a system capable of manipulating unknown objects in such an environment. Our robot is tasked with clearing a table by removing objects from a pile and placing them into a bin. To that end, we address the three aforementioned challenges. Our robot perceives the environment with an RGB-D sensor, segmenting the pile into object hypotheses using non-parametric surface models. Our system then computes the affordances of each object, and selects the best affordance and its associated action to execute. Finally, our robot instantiates the proper compliant motion primitive to safely execute the desired action. For efficient and reliable action selection, we developed a framework for supervised learning of manipulation expertise. To verify the performance of our system, we conducted dozens of trials and report on several hours of experiments involving more than 1,500 interactions. The results show that our learning-based approach for pile manipulation outperforms a common sense heuristic as well as a random strategy, and is on par with human action selection. 相似文献
56.
57.
Anthony G. Dixon 《Chemical Engineering Communications》1988,71(1):217-237
The effective radial thermal conductivity and apparent heat transfer coefficient for a packed bed were experimentally determined for beds of spheres, full cylinders and hollow cylinders, for flow rates giving particle Reynolds numbers in the range 100-1000, and for tube to particle diameter ratios of 5-12. Over these ranges the radial Peclet number Per showed significant dependence on solid conductivity, gas flow rate and particle shape, while the wall Biot number Bi showed significant dependence on tube to particle diameter ratio, gas flow rate and particle shape. These dependencies were predicted well by equations incorporating the effects of these variables into individual gas and solid phase parameters, which were then combined to give the effective or lumped parameters 相似文献
58.
Frank Zok Orfeo Sbaizero Craig L. Hom Anthony G. Evans 《Journal of the American Ceramic Society》1991,74(1):187-193
The mode I fracture resistance of a ceramic matrix composite has been measured. Simultaneous observations have revealed that the resistance is dominated by frictional dissipation upon the pullout of fibers that fracture in the crack wake off the crack plane. Numerical and analytical crack growth simulations have been compared with the experimental results. One important feature in this comparison concerns the occurrence of large-scale bridging. With these effects taken into account, the simulations and the experiments are found to be in good correspondence for acceptable magnitudes of the interface sliding stress. 相似文献
59.
Anthony J. O'Lenick Jr. Jeffrey K. Parkinson 《Journal of the American Oil Chemists' Society》1996,73(7):935-937
A study was undertaken to determine the surfactant properties of various sulfated alcohols. Most notably, the Krafft point
and the ability to emulsify decane were studied. A series of sulfated Guerbet alcohol and Guerbet alcohol alkoxylate sulfates
with 16 carbon atoms and an analogous series based upon cetyl alcohol, a linear C16, were studied as hydrophobes. 相似文献
60.
This work reports a structure-property investigation of a conjugated polymer nanocomposite with enhanced conductivity. Regioregular poly(3-hexylthiophene) (rrP3HT) was used to prepare composites with thin, short, multi-walled carbon nanotube (MWNT) addition over a wide range of concentrations. Scanning and transmission electron microscopies demonstrated an excellent dispersion and good wetting properties within the carbon nanotube composites. Coated MWNTs showed superstructures of P3HT self-organized on nanotube surfaces. Changes in the long range order and on the self-ordered mesophase of the bulk material were investigated by infrared and Raman spectroscopies, differential scanning calorimetry and X-ray diffraction. Interplay between charge transport through the semiconducting polymer and carbon nanotube network increased the composite's conductivity after percolation to values close to 10−2 S cm−1. 相似文献