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81.
Edward Kostansek 《Journal of Coatings Technology and Research》2004,1(1):41-44
Coagulation of latex particles is most often carried out in the diffusion limited aggregation (DLA) regime where the time
for coagulation to take place is on the millisecond timescale. This process produces aggregates of low density, irregular
shape, and a broad particle size distributions. When the coagulation is carried out in the reaction limited aggregation (RLA)
regime, a coagulation time of about 1–120 sec, the system can be controlled by mixing to yield dense, spheroidal aggregates
with a very narrow particle size distribution. The important variables in the RLA process for butyl acrylate/methyl methacrylate
(BA/MMA) latexes were found to be mixing intensity, latex copolymer composition, and coagulation temperature. Dried aggregates
formed in the RLA process were found to have excellent powder flow properties and low dustiness. 相似文献
82.
Michael J. Banach Stephen J. Clarson Gregory Beaucage Jason Benkoski Tom Mates Edward J. Kramer Richard A. Vaia 《应用聚合物科学杂志》2002,86(8):2021-2024
For many microelectronic and optoelectronic applications, polymer thin films require the addition of small molecules. However, the thin‐film geometry and associated processing techniques will influence the final morphology and compositional distribution of the constituents. It is therefore important that these be examined directly rather than inferred from bulk measurements. As an example system, the concentration and distribution of Disperse Red 1 (DR1) molecules in poly(methyl methacrylate) thin films were examined. Ultraviolet visibility spectroscopy and dynamic secondary ion mass spectrometry indicate that the composition of the molecules decreased dramatically with thermal treatment of the film. The sublimation of the chromophore was observed to occur at temperatures well below the melting point of the small molecule and the glass transition of the pure polymer; this solute loss manifested itself in changes in the glass transition temperature of the film. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2021–2024, 2002 相似文献
83.
Pure carbon dioxide was absorbed into distilled water and sodium hydroxide solution, in cocurrent two phase annular flow in helically coiled tubes in order to measure physical and chemical mass transfer coefficients and interfacial areas. (k*La) was correlated by the pressure drop in the test sections and interfacial areas were found to vary with the liquid phase energy dissipation. According to a new theory, (k*L) has been shown to be a function of the root mean square vorticity near the interface. The root mean square vorticity has been related to the pressure drop, gas density, liquid flow rate and liquid velocity. The physical mass transfer coefficients theoretically predicted are in good agreement with experimental results. 相似文献
84.
85.
J. Edward Hunter 《Journal of the American Oil Chemists' Society》1981,58(3):283-287
A major objective of commercial processing of soybean oil into edible products is to remove unwanted impurities from the oil
with the least possible effect on nutritional quality of the oil. Soybean oil is an excellent dietary source of essential
linoleic acid and also of tocopherols, which serve as sources of vitamin E and natural antioxidants. The data presented in
this report indicate that the nutritional quality of soybean oil is largely retained after typical commercial processing conditions.
Hydrogenation does reduce the level of essential fatty acids; however, typical commercial salad and cooking oils and shortenings
made from partially hydrogenated soybean oil retain nutritionally significant levels of essential fatty acids. Tocopherols
also are present at high levels in the finished oil. Among the unwanted components of crude soybean oil which are effectively
removed by processing are pesticide residues, phosphatides, free fatty acids, color pigments, and compounds causing objectionable
odors and flavors. 相似文献
86.
Theerythro andthreo isomers of methyl 9,10-dihydroxyoctadecanoate and thethreo isomer of methyl 12,13-dihydroxy-cis-9-octadecenoate were converted into methylcis- andtrans-9-octadecenoate and methylcis-9,rans-12-octadecadienoate, respectively, by reaction of the dihydroxy ester with triethyl orthoformate to give the 2-ethoxy-1,3-dioxolane
which was thermally decomposed to the unsaturated ester. 相似文献
87.
Summary Cholesterol is a universal constituent of all animal cells and therefore occurs in all foods of animal origin. Cholesterol
is the mother substance of bile acid and of sex hormones and has other important physiological roles. Cholesterol is synthesized
in the body from acetate obtainable from ingested carbohydrate, fat. or protein, of animal or vegetable origin.
The fate of cholesterol in the body has not been definitely established. The cause of atherosclerosis is unknown. Atherosclerosis
occurs in young as well as old individuals. Atherosclerosis is the number-one killer today.
Diagnosis of atherosclerosis in the healthy individual is not possible. Treatment of atherosclerosis is empirical. Reduction
of blood cholesterol levels by dietary means is difficult under conditions consonant with good nutrition. A well-balanced
intake of all available foods on a modified total caloric basis appears to be the practical approach to the problem of fat,
cholesterol, and atherosclerosis.
Presented at the 47th Annual, Meeting, American Oil Chemists’ Society, Houston, Tex., April 23–25, 1956. 相似文献
88.
This paper presents a simplified method for the chemical synthesis of cholest-4-en-3-one, which is a naturally occurring steroid
and a salient intermediate in steroid chemistry. Pyridinium chlorochromate (PCC) in refluxing benzene has been found to be
an effective and convenient reagent for the oxidation and concomitant isomerization of cholest-5-en-3β-ol (cholesterol) to
cholest-4-en-3-one in high yield. Also described are the carbon-13 nuclear magnetic resonance spectral properties of cholest-4-en-3-one
and of the isolated reaction intermediate cholest-5-en-3-one.
Based on a paper presented at the Symposium on Plant and Fungal Sterols: Biosynthesis Metabolism and function held at the
AOCS Annual Meeting, Baltimore, MD, April 1990. 相似文献
89.
Edward J. Rode Paul E. Gee Linda N. Marquez Tetsuji Uemura Mohammad Bazargani 《Catalysis Letters》1991,9(1-2):103-113
Alkali metal zeolites and metal oxides were used for the aldol condensation of n-butanal to 2-ethyl-2-hexenal. The order of activity at 150 °C and 1 atm. was: CsNaY > NaY > LiNaY > MgO >Al2O3. Selectivity to 2-ethyl-2-hexenal was 100% for both pure and mixed isomer feed. Infrared spectroscopic studies showed that stable catalysts were produced by propene pretreatments which blocked Lewis acid sites. Adsorption of ammonia and carbon dioxide on CsNaY during aldol condensation of n-butanal causes a decrease in rate. This result, along with the order of activity, suggests that the presence of both acid and basic sites produce higher activity than strongly basic MgO.Work performed at San Jose State University. 相似文献
90.
时尚是有规律的.它不是以进步的形式运动,而是在循环中运动.外在的一致性通常会破坏内在的一致性.本文就时尚的规律、时尚的产生与运动过程、时尚与限制性规则、现代时尚的新变革等方面展开讨论. 相似文献