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61.
Mertens W. G. Rubin L. J. Teasdale B. F. 《Journal of the American Oil Chemists' Society》1961,38(6):286-289
A fractional crystallization method for the winterization of cottonseed oil with solvents was developed in our laboratories
and pilot plant.
Small amounts of solvent (e.g., 10% by weight of acetone) were mixed with the oil. This mixture was rapidly chilled to 0°C. and kept at this temperature
for 3–4 hrs.; the liquid portion was separated from the solids.
After solvent evaporation a salad oil of good quality was obtained. The yield is equal to or better than that obtained with
conventional methods.
The method is suitable for a continuous operation since rapid chilling can be used, and only a short over-all time is necessary.
Great advantages of the process are the use of low amounts of solvent and of a refrigeration system not requiring temperatures
below 0°C. 相似文献
62.
M. Rubin Z. Halpern A. Livoff A. Wennberg A. Tietz E. Antebi D. Lichtenberg 《Lipids》1992,27(5):321-325
This study was undertaken to determine the effect of various lipid emulsions on the hepato-biliary system in rats. Rats were
randomly divided into six groups and infused continuously for 48 hr with either long-chain triglycerides (LCT), medium-chain
triglycerides (MCT) or a mixture of MCT and LCT. One group infused with physiological saline solution served as controls.
Throughout this period the rats received a fat free dietad libitum. During the last hour of lipid infusion bile was collected for determination of bile flow and composition. Subsequently,
the rats were sacrificed and the morphology and lipid content of the liver determined. Only LCT lipid emulsions induced morphological
changes and increased liver cholesterol content. In two rats infused with radiolabeled LCT, no labeled cholesterol was found
in the liver, indicating that the excess hepatic cholesterol level may originate from enhanced cholesterol mobilization to
the liver. Biliary cholesterol and phospholipid concentrations in LCT-treated rats were also elevated, as was the lithogenic
index, whereas the other emulsions had no such effects. None of the emulsions affected the plasma liver function tests or
bile flow. We therefore conclude that the lithogenicity of the bile in rats is directly related to the lipid components of
the total parenteral nutrition and the type of triglyceride infused. 相似文献
63.
Ammoxidation of toluene over the perovskites YBa2Cu3O6.1, YBa2Cu2CoO6.7 and YBaCuCoO4.9 was investigated at 400 °C. At low partial pressures of O2 benzonitrile was selectively formed, while CO2 was the main product at high pressures of O2. Systematic differences in activity were observed for the three phases and are related to the crystal contents of Cu and Co. At low O2 pressures, Cu-sites are active for nitrile formation, while Co-sites give CO2. At high O2 pressures, the activity for CO2 of Cu-sites increases more than that of Co-sites due to filling of near-surface oxygen vacancies. 相似文献
64.
Aziz Rezig Tinh Nguyen David Martin Lipiin Sung Xiaohong Gu Joan Jasmin Jonathan W. Martin 《Journal of Coatings Technology and Research》2006,3(3):173-184
The relationship between chemical degradation and thickness loss of an unpigmented, non UV-stabilized, crosslinked amine-cured
epoxy coating exposed to three UV conditions was investigated. Spin-coated samples having a thickness of approximately 7 μm
on an Si substrate were prepared from a stochiometric mixture of a bisphenol A epoxy resin and a tetra-functional amine curing
agent. Samples were exposed outdoors and to two accelerated laboratory UV environments. Chemical degradation and thickness
loss were measured by transmission Fourier transform infrared spectroscopy (FTIRS) and laser scanning confocal microscopy
(LSCM), respectively. In addition, surface roughness and morphological changes were measured by atomic forcemicrosocopy (AFM)
and LSCM. Substantial chemical degradation, thickness loss, and morpholocal changes occurred in the exposed films, and the
rate of chemical degradation was greater than that due to the thickness loss. This additional chemical loss was attributed
to an inhomogeneous degradation process in which nanoscale localized depressions initiate at certain sites on the surface,
which then enlarge and deepen with exposure time. The results of this study provide a better understanding of the degradation
mechanism and should lead to the development of scientific-based models for predicting the service life of crosslinked amine-cured
epoxy coatings.
Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004, in Chicago,
IL 相似文献
65.
Ceramics for Prosthetic Hip and Knee Joint Replacement 总被引:2,自引:0,他引:2
Mohamed N. Rahaman Aihua Yao B. Sonny Bal Jonathan P. Garino Michael D. Ries 《Journal of the American Ceramic Society》2007,90(7):1965-1988
The most commonly used bearing couple in prosthetic hip or knee joint replacements consists of a cobalt–chrome (CoCr) metal alloy articulating against ultrahigh-molecular-weight polyethylene. Ceramics have been used as an alternative to metal-on-polyethylene in joint replacement surgery of arthritic hips and knees since the 1970s. In prosthetic hip and knee bearings, ceramic surfaces offer a major benefit of drastically reduced wear rates and excellent long-term biocompatibility, which can increase the longevity of prosthetic hip and knee joints. This benefit is important clinically because hip and knee replacement has become a very common surgical procedure, particularly in the United States, and because these procedures are being increasingly performed in younger patients who place greater demands on the prosthetic bearings. However, ceramics are brittle and the risk of catastrophic bearing failure in vivo , while rare, is a major concern. Improvements in material quality, manufacturing methods, and implant design have resulted in a drastic reduction of the incidence of such failures, so that modern ceramic bearings are safe and reliable if used with components of proven design and durability. Future material improvements are actively being investigated to reduce the risk of ceramic-bearing failures even further. The purpose of this article is to review the structure, properties, applications, and limitations of the ceramics that have been used in orthopedic bearings, and to describe the new ceramic composite materials and surface treatments that will be available for joint replacement surgery in the near future. 相似文献
66.
67.
通过使用墙体杀菌清洁与非杀菌清洁后涂料干膜的性能比较,评价了杀菌清洗对提高涂料干膜性能的有效性,揭示了怎样用杀菌清洁提高杀菌系统的特性。同时,比较了传统杀菌剂和新式杀菌剂的性能差别。 相似文献
68.
Nianxue Song Zhengqian Xuan Jonathan K. Bartley Stuart H. Taylor David Chadwick Graham J. Hutchings 《Catalysis Letters》2006,106(3-4):127-131
The use of a periodic flow reactor is described for the oxidation of butane to maleic anhydride to compare the catalytic performance
of vanadium phosphate catalysts operating under aerobic and anaerobic conditions. It is found that for the catalyst prepared
via a standard VPO method, operation in the absence of oxygen leads to a very small enhancement in selectivity when butane
concentrations in the range 0.9–2.9% are used. Operation in the absence of oxygen leads to very small differences in conversion
such that the overall yield is enhanced and this effect is maximised for reactor feeds containing 1.5% butane. However, the
enhancement is negligible when the catalyst is operated at high conversion required for commercial operation, indicating that
reactors operating with continuous flow with aerobic conditions are preferred. Similar experiments are conducted for a catalyst
prepared by the VPD method and, in contrast, this catalyst gives lower butane conversion and maleic anhydride selectivity
when operated in the absence of oxygen. 相似文献
69.
Two-dimensional correlation relaxometry studies of cement pastes performed using a new one-sided NMR magnet 总被引:1,自引:0,他引:1
Peter J. McDonald Jonathan Mitchell Peter S. Aptaker Luc Monteilhet 《Cement and Concrete Research》2007,37(3):303-309
We present preliminary results of the first NMR T1-T2 two-dimensional relaxation correlation experiments performed using a one-sided NMR system in cement based materials. Two-dimensional correlation relaxometry has itself only recently been demonstrated in cement paste where it proved to be a particularly sensitive probe of pore-water dynamics providing direct information on exchange of water between the gel and capillary pore networks. Further to this we have observed differences in the structural development of a selection of cement pastes throughout the early stages of hydration and verified the theoretical frequency dependence of the ratio T1 / T2. When coupled with instrumentation developments in one-sided NMR magnets the way is opened to detailed, spatially resolved studies of the development of hydration and porosity in the surface layers (top 50 mm) of cementitious materials. A new magnet, suitable for such applications, is discussed. 相似文献
70.
The action of the tumor promoter, phorbol 12,13-dibutyrate (PDBu), on rabbit peritoneal and human neutrophils is associated
with stimulation of14C-arachidonic acid incorporation into phospholipids within 1–2 min. Stimulated14C-arachidonate incorporation was relatively selective for phosphatidylinositol (PI) in rabbit neutrophils. In contrast, the
secretory response of human neutrophils to PDBu coincided with stimulated label incorporation into phosphatidylserine (PS),
phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidic acid (PA) and PI. Significant increases in label incorporation
were observed with PDBu concentrations as low as 2 nM, and the dose response of stimulated label incorporation paralleled
that of evoked lysozyme secretion. A parallel, but partial, inhibition of PDBu-stimulated PI labeling and enzyme release was
observed after exposing rabbit neutrophils to calcium-deprived medium, whereas calcium deprivation failed to significantly
depress either of these stimulant actions of PDBu in human neutrophils. Further, in rabbit neutrophils PDBu elicited an increase
in cell associated45Ca. However, PDBu was unable to promote the incorporation of32P orthophosphate into PI or enhance phospholipase A2 activity in broken cells. These findings suggest that one expression of the interaction between phorbol esters and their
receptors on neutrophils involves the turnover of arachidonic acid in phospholipids. This stimulated turnover of arachidonate
may be a critical step in the cascade of events associated with neutrophil activation. 相似文献