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21.
The synthesis of a series of 2-thioethers of 1,4-dihydroxyanthraquinone by various preparative routes is described. The colour, dyeing and fastness properties on synthetic-polymer fibres of these dyes is discussed in terms of the nature of the substituent in the thiol group. 2-(2-aminophenylthio)-l, 4-dihydroxyanthraquinone, which gave the new heterocycle 6,13-dihydroxyanthra-[2,3-b]benzo[d] thiophen-7,12-dione on Pschorr intramoleadar cyclization, was observed to undergo cyclization, during both its synthesis and its application to polyester fibres, to the blue coloured 7-hydroxy-14H-mphtho[2,3-a] pheno-thiazine-8,13-dione. 相似文献
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This paper solves the machine interference problem in which N different machines are looked after by a team of r operatives. The run time of each machine is assumed to have a general distribution, different for each machine and the repair times are assumed to have a negative exponential distribution with different means for the different machines. An explicit expression for the probability that a particular group of machines is found running in the steady state is derived. From this other useful measures for the system can be obtained. It is shown that these depend on the run time distributions only through the means of those distributions. 相似文献
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BRIAN HANLEY STEVEN BALLOGE MATTHEW TIRRELL 《Chemical Engineering Communications》2013,200(1-3):93-113
The Trommsdorf or gel effect in free radical polymerization is due to the fact that the termination reaction becomes strongly diffusion controlled above a critical concentration associated with the onset of molecular entanglements. Therefore, an understanding of polymer self-diffusion in entangled systems becomes essential to understanding the Trommsdorf effect. Our group has previously proposed a molecular model for the gel effect which uses a specific theory for polymer diffusion (reptution). The present work represents an experimental attack on the same problem Experimental studies of polymer self-diffusion in entangled systems are scarce. Quasielastic light scattering from ternary systems composed of solvent(l)-polymer(2)-polymer(3), in which species (3) is isorefractive to the solvent (i.e. 0n/0c 3 = 0), offers an attractive way to study the tracer diffusion coefficient of species (2) in a binary mixture of composition c 3. In regimes of low momentum transfer (qR G < 1,) where q is the scattered wave vector and R G is the polymer radius of gyration, we have shown that the correlation function of the scattered electric field should decay with a single exponential decay time, given by (D22 q 2)?1 where D 22(c 2, c 3) is the main ternary diffusion coefficient of component (2). Extrapolation to zero concentration of 2) at fixed concentration of (3) yields the tracer diffusion coefficient of (2) in the binary mixture of (1) and (3). The systems toluene(l)-polystyrene(2)-polymethylmethacrylate(3) (0n/0c 3 ≈ 0.007 at 25°C) and toluene(l)-polystyrene(2)-polyvinylmethylether (3) (0n/0c 3 ≈ 0.012 at 60°C) very nearly satisfy the above criteria. In both systems, we have found that the tracer diffusion coefficient of the polystyrene decreases with increasing concentration of the isorefractive polymer. Further studies have focused upon the dependence of the tracer diffusion coefficient upon polystyrene molecular weight, and upon the effect of incomplete index matching. 相似文献
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Abstract Story grammar was a fairly hot topic in artificial intelligence (AI) from the mid-1970s to the early 1980s. Now, however, it has virtually disappeared as a research issue in AI. The process of science is one where theories are proposed, experiments are conducted, hypotheses are tested, theories are revised and, ultimately, theories are either accepted or rejected. The story grammar story is surveyed with a view towards describing what it was, and explaining what happened to it, from the perspective of the scientific process. 相似文献
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CREINA S. STOCKLEY LESTER H. SMITH the late KEVIN G. TILLER BRIAN L. GULSON CHESTER D'A. OSBORN TERRY H. LEE 《Australian Journal of Grape and Wine Research》2003,9(1):47-55
Sources of lead in wine were inferred from systematic assay of grapes must and wine, during winemaking. Two Australian wineries were monitored during the 1994 vintage with respect to vinification of Riesling and Shiraz. Juice and wine samples were collected at several process stages from crushing through to bottling, and were analysed for their total lead concentration by graphite furnace atomic absorption spectrometry. Selected samples were subsequently analysed for lead isotope ratio (fingerprinting method) to infer possible sources of lead in samples. Lead concentration in fermenting must was found to vary during vinification. In particular, lead concentration increased significantly in open-top vessels, in holding bins and during pressing. Juice and wine stored in concrete or waxed wood also had a significantly higher concentration of lead compared to juice or wine stored in stainless steel. Moreover, fining with bentonite or filtering with diatomaceous earth contributed further to final lead concentration, while fermentation, both primary and secondary, removed lead Overall, wines processed via these different systems still contained only traces of lead, and generally less than 30 μg/L (30 micrograms per litre). These trace levels are of no concern to human health when such wines are consumed in moderation. 相似文献
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BRIAN PEACE 《International Journal of Dairy Technology》1987,40(1):1-4
The impact of the historical changes in the dairy farming industry, and of the changes recently introduced by the EEC, is described in relation to the responses of an individual dairy farmer in the south west of England. 相似文献
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