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11.
12.
Differential thermal contraction between matrix and fiber materials in composites and between adhesive and adherend materials in adhesive joints occurs during cooling from the resin cure temperature and gives rise to non-uniform internal stress fields. Resin swelling associated with water uptake during service gives rise to inhomogeneous stress, the magnitude and distribution of which is the subject of the present investigation. Thin layers of cured epoxy resin have been allowed to absorb water at their edges only, and the swelling normal to these layer planes has been measured by studying optical interference patterns. The stresses resulting from inhomogeneous swelling, a few tens of bars, are of similar magnitude to those resulting from inhomogeneous shrinkage during cooling from resin cure temperatures. 相似文献
13.
Phosphatidylethanolamine (PE) and phosphatidylglycerol (PG) were isolated from aVibrio species of bacterium, known to produce eicosapentaenoic acid (20∶5n−3) andtrans-hexadecenoic acid (16∶1n−7), and subjected to phospholipase A2 degradation to determine the positional distribution of component fatty acids. At the two growth temperatures studied (20
and 5°C), both 20∶5n−3 andtrans 16∶1 n−7 were located mainly at positionsn−2 in PE. Increases in the proportions of 20∶5n−3 andtrans 16∶1n−7 in positionsn−2 with decreasing growth temperature were balanced mainly by decreases in the level ofiso-15∶0. In PG,trans 16∶1n−7 was located predominantly in positionsn-1, although the difference between the two positions was not as great as in PE. Eicosapentaenoic acid was preferentially
located in positionsn-2 of PG, particularly at 5°C when it comprised 29.9% of the total fatty acids in this position. It is concluded thattrans 16∶1n−7/20∶5n−3 is not a major molecular species of phospholipid in this species ofVibrio and that changes in the levels of molecular species of PE containingiso-15∶0 may feature in thermal acclimation. 相似文献
14.
15.
Five groups of salmon, of initial mean weight 127±3 g, were fed increasing levels of dietary linseed oil (LO) in a regression
design. The control diet contained capelin oil (FO) only, and the same oil was blended with LO to provide the experimental
diets. After an initial period of 40 wk, all groups were switched to a finishing diet containing only FO for a further 24
wk. Growth and flesh lipid contents were not affected by dietary treatment. The FA compositions of flesh total lipids were
linearly correlated with dietary FA compositions (r
2=0.88–1.00, P<0.0001). LO included at 50% of added dietary lipids reduced flesh DHA and EPA (20∶5n−3) concentrations to 65 and 58%, respectively,
of the concentrations in fish fed FO. Feeding 100% LO reduced flesh DHA and EPA concentrations to 38 and 30%, respectively,
of the values in fish fed FO. Differences between diet and flesh FA concentrations showed that 16∶0, 18∶1n−9, and especially
DHA were preferentially retained in flesh, whereas 18∶2n−6, 18∶3n−3, and 22∶1n−11 were selected against and presumably utilized
for energy. In fish previously fed 50 and 100% LO, feeding a finishing diet containing FO for 16 wk restored flesh DHA and
EPA concentrations, to ≈80% of the values in fish fed FO throughout. Flesh DHA and EPA concentrations in fish fed up to 50%
LO were above recommended intake values for humans for these EFA. This study suggests that LO can be used as a substitute
for FO in seawater salmon feeds and that any reductions in DHA and EPA can be largely overcome with a finishing diethigh in
FO before harvest. 相似文献
16.
Three-dimensional holograms were recorded in a cerium-doped, strontium barium niobate (SBN:75) photorefractive crystal. These holograms are shown to not degrade after more than one week of continuous readout and to reconstruct reproductions of the original object with an observable field of view of approximately 35 degrees. 相似文献
17.
Neutrophil function is reduced in periparturient dairy cows. Possible factors that reduce neutrophil function include endocrine changes associated with parturition and metabolic stresses associated with lactogenesis. In this study, mastectomized and intact cows were studied to specifically examine the effects of lactogenesis on neutrophil function in periparturient cows. Expression of adhesion molecules on neutrophils (L-selectin, mediating capture and rolling adhesion, and beta 2-integrin, mediating tight adhesion vital to egress) and neutrophil myeloperoxidase activity (an index of bactericidal activity) were assessed in mastectomized and intact cows. Expression of L-selectin decreased at parturition followed by rapid recovery to prepartum values in both intact and mastectomized cows. Expression of beta 2-integrins increased in intact cows at parturition but not in mastectomized cows. Expression of beta 2-integrins was greater in intact cows than in mastectomized cows throughout the study. Neutrophil myeloperoxidase activity decreased from baseline prepartum values as parturition approached in both intact and mastectomized cows, which suggests the endocrine changes associated with the act of parturition are predominant factors causing loss of neutrophil function. Myeloperoxidase activity recovered to prepartum values within a week of parturition in mastectomized cows; however, myeloperoxidase activity remained depressed in neutrophils obtained from intact cows throughout the first 20 d of lactation. The presence of the mammary gland and its attendant metabolic stresses slowed recovery of neutrophil function, which suggests that the metabolic stress of lactation exacerbated periparturient immunosuppression. 相似文献
18.
19.
Cell free studies have shown that liver and intestine are the major sites of synthesis of triacyl glycerols inSqualus acanthias. The liver and to a lesser extent the intestine and stomach are major sites of wax ester synthesis. Muscle does not synthesize
either triacyl glycerols or wax esters significantly. In vivo studies have shown that intravenously injected (3H) fatty alcohol is massively oxidized to (3H) fatty acid, the bulk of which appears in muscle. Liver appears to export both free fatty acids and triacyl glycerols to
serum and thence to muscle. Free fatty acids, triacyl glycerols, wax esters and cholesteryl esters are all turned over within
48 hr inSqualus serum. The turnover of triacyl glycerols greatly exceeds the turnover of alkyl diacyl glycerols. 相似文献
20.
S. P. Agrawal G. A. Sargent H. Conrad 《Metallurgical and Materials Transactions B》1974,5(11):2415-2422
Hexagonal dislocation networks which occurred in as-annealed commercial Ti-A 50 rod and following partial extrusion under
hydrostatic pressure at room temperature were studied using transmission electron microscopy. For the as-annealed condition
networks were observed on the prism, basal and {2•1•1x} planes, while for the extrusion networks were only observed on the
basal plane. The various stages in the development of the networks are presented and mechanisms by which they form are proposed.
The self energies of the dislocation hexagons constituting the various networks are calculated using the equations proposed
by de Wit and Ruff. They increase in the order: a) networks on the basal plane in the as-annealed condition, b) networks on
the prism plane in the asannealed condition and c) networks on the basal plane in the partially extruded condition.
This paper is based on Doctoral Thesis presented in October 1973 by S. P. AGRAWAL to the Department of Metallurgical Engineering
and Materials Science at the University of Kentucky. 相似文献