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Abstract  

The exothermal process of curing of thermoset resins in adiabatic conditions cannot be monitored by differential thermal analysis techniques such as DSC. Starting from the specific reaction rate, heat capacity as function of the temperature and the heat of reaction at some reference temperature, it is possible to design any adiabatic operation. In this paper we apply the energy balance to the curing process in adiabatic conditions and solve the basic rate law for the two empirical kinetic functionsf(α) usually used:n th-order kinetics [f(α)=(1−α)n], and autocatalytic kinetics [f(α)=αm(1−α)n], where α is the degree of conversion andn andm the reaction orders, in order to obtain the heat generation curve (dH/dt) as a function of time, as well as the change of temperature with time, the explosion time, the maximum adiabatic temperature and the rate of reaction as a function of the degree of conversion.

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A six-day workshop, developed for providing information on sources and effects of radioactive waste disposal to the general public, is described. The materials were used successfully with a group representing the general public. An extension of the workshop for high school and junior high school science teachers is discussed. *** DIRECT SUPPORT *** A0653119 00009

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Abstract  

Wastes containing radioactive materials have been produced ever since ore recovery and processing began; however, such materials did not become of public concern until the large-scale activities involving uranium and thorium ores and nuclear fission during and after World War II. Efforts to provide disposal sites for radioactive wastes, especially those associated with nuclear weapons and nuclear energy, have been largely unsuccessful for the past 40 years or so and are nearing crisis proportions as the new millennium begins — its eventual resolution is believed to require greater reliance on stewardship and a larger governmental presence.

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This paper presents a methodological analysis of the latest update of the CHI/NSF Science Literature Indicators Data-Base. The data-base contains a range of publication and citation indicators borken down by country and field or subfield, and now convers the period from 1973 to 1984. It can be used to draw comparisons of the changing output and impact of basic research in different countries. Earlier applications of the data-base have been constrained by various technical limitations, and have been subject to certain criticism. In this article, after some conceptual analysis of what aspects of scientific performance the different indicators relate to, we show that much of the criticism is misplaced. We also describe subsequent methodological improvements to the indicators and the effect these have on the policy use that can be made. Finally, we examine what the latest statistics reveal about the relative international standing of seven leading scientific nations.

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After explaining the reasons why science policy-makers face a growing need for more rigorous forms of research evaluation, we outline an approach combining bibliometric and peer-evaluation data that has been developed at the Science Policy Research Unit in the course of a programme of studies of Big Science specialties. The paper describes the results obtained when this method of converging partial indicators is applied to compared the past research performance of the accelerators at CERN — the joint European Laboratory for Particle Physics — with that of the world's other main accelerators. The paper concludes by demonstrating how, on the basis of an analysis of the factors that have structured research performance in the past, it is possible to arrive at a systematic set of conclusions about the future prospects for a major new research facility such as an accelerator.

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Abstract  

The spherulite growth, nucleation-related,K g, parameter values obtained from isothermal data (by DSC or optical microscopy) and two other adjustable parameters (the spherulite growth rate preexponential factor and the Avrami's or Tobin's exponent,n) have been used with Nakamura's and Tobin's modified non-isothermal equations to model the kinetics of polymer non-isothermal crystallization. Malkin's model was also tested, for comparison. It is shown that, for polymers that crystallize on cooling almost entirely at temperatures higher than the maximum growth rate temperature, this Tobin's-like non-isothermal model accurately describes the experimental behaviour with only 2 parameters.

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Hordeum chilense Roem. et Schult. is a South American wild barley that occurs exclusively in Chile and Argentina, where it is a component of natural pastures. This species has been crossed with durum and bread wheats to obtain a new amphiploid, called tritordeum, which presents agronomic traits of a new crop. Two groups represented by H1 and H7 lines have shown differences for spike length and density, number of spikelets per spike and various other characters which are interesting for tritordeum improvement. This study was conducted to investigate inheritance of these three characters in a cross between H1 and H7 lines, including parents, F 1 and F 2 generations. The three characters studied fitted the additive model. The dominance effects were less strong than the additive effects, indicating partial dominance of positive sign for number of spikelets per spike; whereas spike length displayed small dominance effects of negative sign and the spike density showed intermediate inheritance, with the inheritance being almost exclusively additive.

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Abstract

It has been suggested that certain physical cues can be used to predict mate quality, and that sensitivity to these cues would therefore be adaptive. It follows that in environments where the optimal values for these features differ, attractiveness preferences should also be different. In this study, we show that there are striking differences in attractiveness preferences for female bodies between Thai observers in affluent, industrialised environments as compared to Thai observers in resource-poor, hill tribes. These differences can be explained by different local optima for survival and reproduction in the two environments. In industrialised societies, a high body mass is correlated with low health and low fertility, and the converse is true in rural Thailand. These results suggest that humans have mechanisms for acquiring norms of attractiveness that are highly plastic, and which allow them to adapt to different ecological conditions through learning.

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Abstract  

The transformation of VOHPO40.5H2O (VPO) precursor doped with cobalt or iron for n-butane oxidation to maleic anhydride was investigated by thermogravimetric analysis under air and nitrogen, with and without n-butane in the flow. While almost no effect was observed in nitrogen or air, a strong influence of the doping was observed when n-butane was added to the nitrogen or air. This resulted in a delay of the decomposition of the precursor and a further reoxidation of the VPO catalyst, particularly for doping with cobalt at low percentage (1%). This shows that doping can change the oxidation state of vanadium phosphorus oxide catalysts, which can explain differences in their catalytic performances and the favourable effect of doping by cobalt.

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