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61.
G. SCOTT GLAESEMANN JOHN E. RITTER Jr. KARL JAKUS 《Journal of the American Ceramic Society》1987,70(9):630-636
Mixed-mode failure of soda-lime glass under inert and fatigue test conditions was studied using Knoop indentation flaws. For annealed cracks (residual stress-free) crack extension (catastrophic or subcritical) is by an abrupt transition from the initial crack plane to a noncoplanar crack plane followed by a reorientation of the crack normal to the applied stress. Although fatigue strength of these inclined flaws increased linearly with respect to orientation of the flaws to the applied stress up to an angle of 60°, this increase was considerably less than what was predicted by existing theories. It is believed that subcritical crack growth causes the crack to be realigned perpendicular to the applied stress before failure for all orientations; hence, fatigue strength does not show the dramatic increase at orientation angles as predicted by theory. For as-indented cracks the contact residual stress causes the crack extension to be less inclined to the initial crack plane than for annealed cracks, but in this case also, the crack realigns itself perpendicular to the applied stress. Again, fatigue strength is relatively insensitive to the orientation angle as predicted by theory and subcritical crack growth is believed to play a primary role in determining this strength dependency. 相似文献
62.
Reed M. Izatt Steven R. Izatt Don W. Mcbride Jr. Jerald S. Bradshaw James J. Christensen 《Israel journal of chemistry》1985,25(1):27-32
Macrocycle-mediated fluxes of Cd(NO3)2 and of several binary mixtures of Cd(NO3)2 with the nitrate salt of either Na+, K+, Rb+ Cs+, Ag+, Ca2+, Sr2+, Pb2+, Zn2+, or Cu2+ have been determined in a H2O-CHCl3–H2O liquid membrane system. Of the macrocycles studied, 2.2 and 2.2DD most successfully transported Cd2+ In the Cd2+–Mn+ mixtures, Cd2+ was transported selectively with 2.2 when Mn+ was either an alkali or an alkaline earth cation. However, when Mn+ was either Ag+, Pb2+, or Cu2+ the Cd2+ flux was reduced sharply. Generally, cation flux was greater for 2.2DD than for 2.2 with selectivity for Cd2+ being altered also in several cases. Relative fluxes from binary cation mixtures depend on metal cation radius, macrocycle cavity diameter, ligand ring substituent and log K for metal ion-macrocycle interaction. 相似文献
63.
T. J. WEiss Mona Brown H. J. Zeringue Jr. R. O. Feuge 《Journal of the American Oil Chemists' Society》1971,48(4):145-148
Thin layer chromatography was adapted for direct quantitative estimation of sucrose esters of palmitic acid. Urea-phosphoric
acid spray was used to detect the sucrose moiety of the various esters. The photometrically metermined density density of
each spot on the thin layer plate was found to be proportional to its sucrose content. Ester content was then obtained by
multiplying sucrose found by the factor, mol. wt. ester/mol. wt. sucrose. Ester mixtures were prepared by interesterifying
sucrose with various proportions of methyl palmitate in dimethylformamide solution. Positional isomers were observed at each
level of substitution but could not be adequately separated from each other for quantitative evaluation.
Presented at the AOCS Meeting, Minneapolis, October 1969.
So. Utiliz. Res. Dev. Div., ARS, USDA. 相似文献
64.
Effects of hyperlipemia on circulating leukocytes and erythrocytes were studied in dogs which were given repeated, intravenous
injections of a nonionic detergent, Triton WR-1339.
Erythrocyte lipid concentrations increased from 3.6±0.9 mg/1010 cells in control animals to 9.3±1.5 mg in the hyperlipemic group. This increase was accompanied by a shift in the distribution
of total fatty acids toward a higher percentage of saturated and monounsaturated acids. In contrast to the changes observed
in erythrocytes, the leukocyte lipid content remained unaltered in dogs with serum cholesterol levels ranging from 500 to
more than 2,000 mg/100 ml. Leukocyte counts rose whereas hematocrit values, hemoglobin concentrations, and erythrocyte counts
decreased. Oxygen utilization studies showed no significant metabolic differences between leukocytes which were isolated from
hyperlipemic or control animals. Circulating leukocytes in dogs with an endogenously induced hyperlipemia were shown therefore
to maintain normal lipid concentrations and did not participate in lipophage formation, as reported for certain diet-induced
lipemias. 相似文献
65.
William E. Cooper Jr. 《Journal of chemical ecology》1991,17(5):849-863
The ability to discriminate prey chemicals from control substances and the presence of a poststrike elevation in tongue-flicking (PETF) rate are experimentally demonstrated in the lacertid lizard,Podarcis muralis, The tongue-flick attack score, a composite index of response strength, was significantly higher in response to integumental chemicals from cricket than to cologne or distilled water. The cricket chemicals additionally elicited a significantly greater rate of tongue-flicking and higher proportion of attacks by the lizards than did control stimuli. PETF combined with apparent searching movements strongly suggest the presence of strike-induced chemosensory searching (SICS). Experimental evidence indicates that both PETF and SICS occur in insectivorous representatives of three families of actively foraging autarchoglossan lizards, suggesting their widespread occurrence in such lizards. The adaptive roles of chemosensory behavior in the foraging behavior of P.Muralis are discussed. It is proposed that these lizards may form chemical search images and that PETF and SICS may have been present in the lacertilian ancestors of snakes. 相似文献
66.
Henry J. Pownall Joel D. Morrisett James T. Sparrow Louis C. Smith James Shepherd Richard L. Jackson Antonio M. Gotto Jr. 《Lipids》1979,14(4):428-434
The human plasma high density lipoproteins (HDL) are a heterogeneous ensemble of five proteins associated with both neutral
and polar lipids. The sequences of all five proteins are known. ApoA-I and apoA-II are the major protein components; apoC-I,
apoC-II and apoC-III are the minor protein components. All these apoproteins spontaneously recombine with phospholipids to
give stable lipid-protein complexes and freely exchange between the two major HDL subclasses, HDL2 and HDL3. In addition, ApoC-I, apoC-II, and apoC-III exchange between HDL and very low density lipoproteins. Furthermore, certain
HDL apoproteins are activators for plasma enzymes that are important in lipid metabolism. ApoA-I and apoC-I activate lecithin/cholesterol
acyltransferase; apoC-II is an activator of lipoprotein lipase. The regions of apoC-I and apoC-II that are involved in the
activation of these enzymes have been localized with synthetic peptides. Studies of synthetic and native fragments of apoA-II,
apoC-I, apoC-II, and apoC-III as well as model lipid-binding peptides have identified specific regions with structural features
common to lipid-binding proteins. These special properties, which include helical potential, sequences with a critical amphipathic
length, and high hydrophobicity of the nonpolar side of the amphipathic helix, are the determinants of HDL structure and metabolism. 相似文献
67.
Emulsion polymer isocyanate (
), polyvinyl acetate (
) and resorcinol-formaldehyde (
) adhesives were used to produce single lap shear specimens using resinous and non-resinous apitong (Dipterocarpus spp.) timbers. Tests showed that joints made with highly resinous apitong were about 40% weaker than similar joints made with non-resinous apitong. The resinous apitong was treated with different solvents to yield five different extractives which were characterized by infra-red analysis. Apitong extractives were then added to
and
adhesives and joints made with buna (Fagus crenata), a timber known to be low in extractives and easy to bond. Joints prepared using extractive-containing adhesives were generally weaker than those made with the unmodified adhesives. RF adhesives containing extractives cured more slowly than unmodified
. It is thought that the acidic nature of the extractives changes the pH of the system sufficiently to affect the curing mechanism 相似文献
68.
William D. Bedard Kenneth Q. Lindahl Jr. Paul E. Tilden David L. Wood 《Journal of chemical ecology》1985,11(9):1249-1261
After living ponderosa pines were baited with either female-infested bolts or synthetic pheromones,Dendroctonus brevicomis were caught on sticky screens throughout trapping periods of 15–46 days; however, large numbers of beetles were trapped during only a small portion (5–10 days) of these trapping periods. The most attractive portions of trees attacked contained 3–6 beetles dm2, in galleries ca. 2 cm long. Catch increased following addition of males to female-infested bolts, supporting the hypothesis that male-produced frontalin is an attractive pheromone of the western pine beetle. Catch at bolts removed from trees under attack was strongly dependent upon levels of boring activity. We found no evidence of interruption of the response to attractants during host colonization.Coleoptera: Scolytidae. Trade names and commercial enterprises or products are mentioned solely for information and do not constitute endorsement by the U.S. Department of Agriculture or University of California. 相似文献
69.
Patricia Quinlin Herman J. Weiser Jr. 《Journal of the American Oil Chemists' Society》1958,35(7):325-327
Summary Monoglyceride concentrates are quantitatively separated into mono-, di-, and triglyceride components on silica gel columns
by an adsorption chromatographic technique. The separated glycerides are determined gravimetrically. The adsorption on silica
gel is dependent on the number of hydroxyl groups in the molecule, and the influence of unsaturation and chain length is minimized.
Combinations of benzene and ethyl ether are used for elution, thus preventing isomerization, which frequently results when
polar solvents such as alcohols are used.
The procedure for the chromatographic separation is simple and straightforward. The equipment used is easily obtainable. The
silica gel adsorbent requires only adjustment of its water content before use.
Mixtures of both saturated and unsaturated glycerides and those having different fatty acid chain length have been separated.
Known mixtures have also been analyzed. For a known mixture containing 15% tripalmitin, 45% distearin, and 38% monopalmitin
the average deviations from the calculated values were 0.4%, 0.2%, and 0.6%, respectively 相似文献
70.
R. G. Bistline Jr. W. R. Noble W. M. Linfield 《Journal of the American Oil Chemists' Society》1974,51(4):126-132
Alkylbenzenes, such as industrial detergent alkylates, as well as pure 1-phenylalkanes whose side chain lengths varied C8−C12, were converted into the corresponding alkylbenzenensulfonyl chlorides with chlorosulfonic acid. Surface active sulfonamides were obtained from the reaction of the sulfonyl chlorides with various low mol wt aminosulfonic acids, such as N-methyltaurine, or with aminoalkyl esters of sulfuric acid, such as 2-aminoethyl hydrogen sulfate. The hydrolytic stability of the resulting surface active sulfonamide derivatives was investigated. As expected, the sulfonates were quite resistant to acid or alkaline hydrolysis, while the sulfates were more susceptible to hydrolysis. Hydrolytic stability of the sulfonamides was compared with that of the analogous fatty acid amide sulfactants. All of the compounds were excellent lime soap dispersing agents giving Borhetty-Bergman values of 4–10. The compounds were evaluated for detergency either alone or formulated either with tallow soap or with tallow soap and sodium silicate (Na2O/SiO2 ratio of 1∶1.6) The derivatives of the pure hydrocarbons which gave the best overall detergency were those of 1-phenyldecane and 1-phenyldodecane, whereas those of 1-phenyloctane exhibited poor detergency. This ranking was observed when the compounds were tested alone as well as when formulated. The sulfonamide derivatives of the detergent alkylate type of alkylbenzenes exhibited excellent detergency characteristics and showed substantial potentiation of detergency when mixed with soap or with a soap-sodium silicate blend. The detergency performance of some of these formulated detergents was equal to that of a commercial household detergent used as a control. 相似文献