Comparative Studies on PAH in Pitch by Liquid Chromatography/Fluorescence and Other Methods

In order to evaluate the PAH toxicity potential of our Söderberg cell emissions, a first PAH HPLC/F1 method was developed in the early 1990′s. A quality control of PAH measurements, based on the B[a]P Eq. Index of homogeneous, stable reference materials, was implemented to follow the pitches used in the fabrication of anode pastes. This technique employed megabore columns (4.6-mm o.d.) with twin fluorescence detectors. In the mid-1990′s, this method was upgraded to minibore columns in order to increase the accuracy. Data for the same pitches was accumulated over a three-year period. This communication compares the results from the two HPLC/F1 approaches including the extraction procedures, the stability of the PAH extracts, the stability of the equipment, the temporal resolution, the wavelengths used, etc., which can affect the apparent PAH values. This new method has also been compared with the results from other laboratories using different protocols and techniques including the presence of instrument specific interferences.     

用于轻质碳酸钙生产的旋转列管式干燥机

简要介绍了在轻质碳酸钙行业中具有广泛应用前景的新型高效节能型旋转列管式干燥机的结构、工作原理和特点。本机结构合理，节能高效，降低了污染。     

Deposition of Zn–Co by constant and pulsed current

The initial stages of both Zn–Co and Zn electrodeposition were investigated by electrochemical quartz crystal microgravimetry (EQCM). The initial electrode mass growth, determined under both pulse and constant current conditions, was much higher than predicted by Faraday's law. This was explained in terms of the precipitation of scarcely soluble compounds of zinc on an electrode surface. The EQCM data confirm that the hydroxide suppression mechanism explains the anomalous Zn and Co codeposition. A nonuniform adsorption of brightener (benzalaceton) on the profiled surface was concluded on the basis of plating distribution investigations. The additive adsorbs to a greater extent on the surface projections.     

Application of synchrotron X-ray radiography to the study of dendritic equiaxed microstructure formation in Al–Cu alloys

The phenomena involved during equiaxed growth, which is the most common growth morphology in metal casting, are dynamic. Therefore, in situ investigation is necessary to fully analyse the microstructure formation. Synchrotron X-ray radiography has become a major tool for in situ characterization of solidification in metallic systems. This paper reports on dedicated equiaxed solidification experiments carried out at the European Synchrotron Radiation Facility (ESRF) in Grenoble-France on Al–10 wt.% Cu alloy. The analysis is based on the recorded images obtained through absorption radiography. Equiaxed growth is achieved in nearly isothermal conditions and observed continuously in real time from the early stages of solidification to the final state. The evolution of the dendrite arm lengths and the corresponding growth rates are analysed for two couples of grains in relation with their environment. This analysis suggests that the solutal interaction is dominant between equiaxed grains.     

Différences entre adolescents et adolescentes à quatre taches de visualisation spatiale.

Compared the performance of 64 adolescent boys and 42 adolescent girls (aged 15–17 yrs) on 4 visual-spatial skills tasks. The administrative conditions of these computerized tasks are highly standardized. Three of these tasks, Spatial Visualization, Perception and Spatial Relations, are taken from the Computerized Aptitude Test for adolescents and adults, whereas the 4th task is an adaptation for adolescents of the Puzzle subtest of the Computerized Aptitude Test for infants. The dependent variables are the average success scores and the speed of execution scores derived from latency times in a group of the best scores for each of the 4 tasks. The results show that the adolescent boys are more successful at the Spatial Visualization and Spatial Relations tasks. On the whole, the boys and the girls showed a comparable speed of success, except in the Spatial Relations subtest, where the girls were much faster. The observed differences are interpreted as reflecting the better strategies adopted by the boys to solve mental rotation tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Construction de la technologie pour l'ecole moyenne en France : Un aperçu historique

Résumé

L'aperçu historique est celui des contenus prescrits, des propositions pour l'enseignement et des successives esquisses de la technologie au collège (11–15 ans). À partir de l'identification des tâches, de leurs visées et de leurs références, il caractérise chacune des cohérences provisoirement fixées par un principe fondateur et identifiée par une méthode. Se succèdent ainsi les méthodes des travaux ménagers, des applications modernes, des éléments logiques, du projet technique, des éléments de la qualité et des scénarios. Bien que la technologie soit toujours définie comme un enseignement général contribuant à l'orientation scolaire, elle oscille entre sciences appliquées, activités manuelles et techniques, initiation scientifique et technique ou découverte des réalités sociotechniques. Par conséquent, cette histoire met en évidence les fondements didactiques de cette discipline scolaire et leurs hésitations. S'opposent en particulier, approche d'investigation et approche de réalisation, références domestiques et industrielles, savoirs élémentaires ou projets techniques. L'étude comparée de ces méthodes révèle également les principes de construction de cette discipline scolaire pour en faire un enseignement élémentaire, progressif et flexible. Cette histoire didactique propose ainsi des moyens pour rendre intelligible la structure des curriculums disciplinaires et pour intervenir sur leur construction.     

Predicting the phase equilibria of synthetic petroleum fluids with the PPR78 approach

The PPR78 approach is a group contribution‐based thermodynamic model which combines at constant packing fraction the Peng–Robinson equation of state and a Van Laar‐type g^E model. This article demonstrates that, using classical mixing rules (linear on b and quadratic on a), the PPR78 model may also be seen as a group contribution method for the estimation of the temperature‐dependent k_ij of the widely used PR EoS. Our model is endowed of 15 groups and it is possible to predict the k_ij for any mixture containing alkanes, aromatics, naphthenes, CO₂, N₂, H₂S, and mercaptans. This study exhibits the capability of this approach to predict the phase behavior of synthetic petroleum fluids containing components of different volatilities. The many comparisons between calculated and experimental data on natural gases, crude oils, and gas condensates allow concluding that the PPR78 approach is a successful model for phase equilibria calculations of this kind of mixtures. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

Experimental design for parameter estimation of two time-scale model of photosynthesis and photoinhibition in microalgae

A method for parameter estimation of two time-scale model of photosynthesis and photoinhibition is presented.