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31.
Male rats were fed 100 nM dichlorodiphenyltrichloroethane-14C in oil by gastric tube. Recovery of dichlorodiphenyltrichloroethane-14C in thoracic duct lymph was 60% in 12 hr. Lymph dichlorodiphenyltrichloroethane-14C (97%) occurred in lipoproteins of d<1.006, designated chylomicrons. Mechanical separation of chylomicron triglyceride core
(labeled with triglyceride-3H) from chylomicron membrane (labeled with phospholipid-32P) showed that 97% dichlorodiphenyltrichloroethane-14C was present in triglyceride core. To investigate possible association of plasma clearance of the two core lipids, rats were
pulse injected with chylomicrons, doubly labeled with triglyceride-3H and dichlorodiphenyltrichloroethane-14C. The decay of dichlorodiphenyltrichloroethane-14C in sequential serum samples was rapid (T1/2=2 min) and was independent of triglyceride-3H decay. In tissues removed 14 min after injection of chylomicrons, 30% administered dichlorodiphenyltrichloroethane-14C was found in liver but only 1% in adipose tissue. In hepatectomized (eviscerated) rats, the decay of serum dichlorodiphenyltrichloroethane-14C (T1/2=10 min) was also independent of and more rapid than triglyceride-3H decay. With sucrose density gradients, it was shown that chylomicron dichlorodiphenyltrichloroethane-14C transferred to higher density serum proteins in vitro and in vivo and to bovine albumin in vitro. Thus, dichlorodiphenyltrichloroethane
was transported from intestine largely in the triglyderide phase of chylomicrons; disappearance of chylomicron-dichlorodiphenyltrichloroethane
from the systemic circulation was rapid and partly independent of the presence of the liver and of triglyceride hydrolysis;
some dichlorodiphenyltrichloroethane was transported from serum chylomicrons to albumin or other plasma proteins before tissue
uptake. 相似文献
32.
Theresa E. Gentle Alan R. Bassindale 《Journal of Inorganic and Organometallic Polymers》1995,5(3):281-294
We have recently reported the synthesis of octopus molecules of defined shape and size with molecular weights well into the thousands. These octopus molecules were made by placing eight pendant groups symmetrically about a central silsesquioxane core via the H2PtCl6 catalyzed hydrosilylation of 1-alkenes as well as vinyl- and allyl-siloxanes by T8 hydrogen silsesquioxane, (HSiO32)8. The chemistry of addition was studied and it was found that while the addition of the 1-alkenes to T8 was regioprecise with only -addition being observed, both - and -addition occurred with vinyl-siloxane. In addition, H-vinyl exchange on silicon was observed to occur with addition of vinyl-siloxane to T8. In the current studies, the effect of the hydrosilylation catalyst. homogeneous and heterogeneous, on the regioselectivity of addition and on the extent of exchange on silicon was evaluated. It was found that the heterogeneous catalysts Pt–C, sulfided Pt–C, and Rh–C required higher temperature and longer times to get complete reaction than the homogeneous catalysts. H2PtCl6 and the tetramethyldivinyldisiloxane complex of Pt. Pd supported catalysts were not effective catalysts for this hydrosilylation. The extent of exchange on silicon and the degree of the second mode of addition occurring were higher with the heterogenous catalysts and may be a result of the higher reaction temperatures. 相似文献
33.
In industrial situations, coals interact with solvents or additives to produce liquid fuels, solvent-refined coal, coal extract and metallurgical coke. In these processes there occurs a wide variation in effects or modifications of the coal by these additives. This paper describes the modifications which can occur, using a wide range of rank of coal, when these coals interact and are co-carbonized with a wide range of additives of different chemical properties. The optical texture of the resultant cokes is given special attention. The objective of the paper is to summarize the current state of knowledge of the mechanisms of these interactions. Possible mechanisms of interactions are summarized, kinetic and chemical structural aspects of reactions are outlined, the importance is mentioned of the formation of liquid phases enabling anisotropic optical textures in modified cokes to be created, and the industrial relevance of its possible development is discussed. 相似文献
34.
William R. Chase Muraleedharan G. Nair Alan R. Putnam Saroj K. Mishra 《Journal of chemical ecology》1991,17(8):1575-1584
Acinetobacter calcoaceticus, a gram-negative bacterium isolated from field soil, was found to be responsible for the biotransformation of 2(3H)-benzoxazolinone (BOA) to 2,2-oxo-1,1-azobenzene (AZOB). Experiments were conducted to evaluate the transformation of BOA to AZOB by this microbe in sterile and nonsterile soil. Transformation studies with soils inoculated withA. calcoaceticus indicated that the production of AZOB increased linearly with the concentration of BOA in sterile soil and showed a quadratic trend in nonsterile soils. This also indicated that all soil types studied for the transformation experiments might containA. calcoaceticus capable of the conversion of benzoxazolinones. 相似文献
35.
Several coals of different rank have been carbonized singly and also co-carbonized with acenaphthylene and decacyclene. The resultant cokes were mounted in resin and polished surfaces were examined for optical texture using a polarized-light optical microscope fitted with a half-wave retarder plate. The optical texture can be assessed qualitatively (visually) or quantitatively by a point-counting technique in terms of size and shape of constituent isochromatic anisotropic units. Some cokes from coals were Isotropic. Acenaphthylene was only able to exert a smaller influence than decacyclene on the optical texture of the resultant cokes from co-carbonizations. Decacyclene was able to modify the optical texture for both the low-rank non-fusible and the caking coals. The effects of changing the proportions of coal to additive were examined. Results are interpreted in terms of ‘depolymerization’ of the coal by the action of the additive (as solvent) and also by the action of the additive in modifying the processes of formation of semi-coke via nematic liquid crystals. 相似文献
36.
Reflectance data for vitrinite occurring in torbanites indicate that the mean maximum reflectance and the range of reflectance values are significantly lowered by the presence of alginite. This is the probable cause of apparently anomalous rank gradients in some deep oil exploration wells. Intermaceral effects need to be considered in assessing rank or maturity from vitrinite reflectance, and by inference, in most other methods. The interpretation of the cause of the effect is open to further study but the findings are highly significant in relation to coal utilization, oil and gas exploration, and studies of oil shales. 相似文献
37.
The solubility of H2S and CO2 in aqueous solutions of the sterically hindered amine, 2-amino-2-methyl-1-propanol (AMP), was determined at 40 and 100°C. Partial pressures of C)2 ranged from approximately 2 to 6000 kPa and of H2S from 2 to 2200 kPa. The solubility results were compared with previously reported acid gas solubilities in aqueous monoethanolamine (MEA) solutions. 相似文献
38.
Alan P. Kozikowski Xue-Min Cheng Chun-Sing Li James G. Scripko 《Israel journal of chemistry》1986,27(1):61-65
A new synthesis of 4- and 7-carbon-substituted indoles is described. The overall sequence involves the addition of a nitrile oxide to 1 carboethoxy-2-(or 3-) allylpyrrole, hydrogenation of the intermediate isoxazoline to β-hydroxy ketone and cyclization of the ketol using magnesium or zinc triflate to the substituted indole. This new indole-forming strategy can also accommodate the introduction of oxygen functionality into the indole 6-position. Possible mechanistic aspects of the reaction are detailed. 相似文献
39.
There is a growing emphasis in many countries on matters such as participation in e-government, e-democracy, the provision of forums for online debate, and so on. A critical issue in all of these cases is one of encouraging engagement across a broad spectrum of potentially interested parties and stakeholders. In this paper, we use an ethnographic study of an online event, designed to encourage debate, to explore some critical issues in how the mechanisms productive of debate have shifted in company with the Web 2.0 phenomenon. By contrasting this with a prior study of how players managed their gameplay in a multiplayer pervasive game, we focus upon how different ways of constructing games and events can have serious implications for their ordinary everyday reportability in routine face-to-face interactions. We conclude that designing for reportability should be an active consideration when designing the resources for online debate and consider some ways in which that might be accomplished. 相似文献
40.
Improvement of WAXD patterns from aligned glassy polymers by a numerical desmearing technique is reported. This gives a fibre type diffraction pattern that can be more easily interpreted than radial or cylindrical distribution functions. Application to atactic and quenched isotactic polystyrene shows that the molecular conformations that are found are in agreement with those deduced from i.r. and n.m.r. spectroscopy. For isotactic polystyrene there is significant agreement between the fibre pattern of the aligned glassy polymer and that of the drawn crystalline polymer. 相似文献