A Strategy for Multiple Immunophenotyping by Image Cytometry: Model Studies Using Latex Microbeads Labeled with Seven Streptavidin-Bound Fluorochromes

Multiple immunophenotyping is aimed at identifying several cell populations in a single labeling procedure by their ability to bind combinations of specific labeled antibodies. The present work demonstrates the simultaneous discrimination by using image cytometry of aminomethylcoumarin acetate (AMCA), Lucifer yellow (LY), fluorescein isothiocyanate (FITC), R-phycoerythrin (PE), PE-Texas red tandem (Red613), peridinin-chlorophyll protein (PerCP), and allophycocyanin (APC), which were all bound to latex beads as streptavidin-conjugated fluorochromes. This has been the result of a step-by-step optimization of the several factors affecting the sensitivity and specificity of multiple immunofluorescence analysis. First, 14 streptavidin-conjugated fluorochromes were evaluated by using spectrofluorometry. A primary selection was then made of ten spectrally separable dyes that could be evaluated by using image cytometry. These dyes were bound to latex particles, and specific filter combinations were assembled to minimize crosstalk between fluorophores while preserving sufficient fluorescence intensity and counting statistics. Potential probe associations were then assessed by measuring the emissions of all fluorochromes that were detected by each filter combination. The resulting crosstalk matrix served as the basic tool both for final selection of the optimal filter combination and for dye set (composed, in this case, of the seven fluorochromes described above) and for mathematical correction of residual spectral overlap. Next, an image cytometry system was adapted to collect seven images of matched brightness with the selected combination of excitation/emission filters and dichroic mirrors. Finally, seven-parameter synthetic images were generated by digital image processing

Design and sizing of electromagnetic linear actuators for valve applications

International audienceIn this paper, various structures of linear motion actuators are described. These structures have been studied in order to drive the valves of a car motor. According to general specifications, a description of the design and sizing of variable reluctance or permanent magnet devices is given. The main qualities of each structure are enhanced

Les nouvelles technologies et l’emploi au Québec : Les industries du textile, des pâtes et papiers et des institutions d’épargne et de crédit

La plupart des travaux concernant l’impact des technologies nouvelles, en particulier l’électronique, sur l’emploi sont trop généraux ou trop techniques. La recherche en cours, dont l’article qui suit ne constitue qu’une étape, se veut une approche à la fois « micro » et « macro-économique ». D’une part, elle analyse l’effet des nouvelles technologies selon les divers segments du processus de production dans des firmes représentatives des différents niveaux de modernisation. D’autre part, elle tient compte de variables générales telles la concurrence, les possibilités des marchés ou les problèmes d’approvisionnement. Les présents résultats, basés sur l’analyse de trois industries des groupes majeurs du textile, des pâtes et papiers et des institutions d’épargne et de crédit sont plutôt pessimistes quant à l’emploi sectoriel; mais ils doivent être complétés par l’étude d’autres groupes industriels, par des études sur les possibilités de nouveaux emplois et par des analyses de cohérence, à l’aide du modèle économétrique CHOIX.Many studies on the effects of new technologies on employment, particularly in the field of electronics, are often either too general, too technical, or both. This paper, which is part of a larger research project, attempts to avoid these pit-falls by presenting a "micro" as well as a "macro" analysis. In the first part, it does it by studying new technologies as they become part of the process in different stages of production, in representative firms of different levels of automation. In a second part, it complements the results of the first in taking into account competition, market capacity or other external variables. The preliminary results of the analyses made on the three industries tend to indicate rather pessimistic trends; but they call for more studies in other sectors, on new jobs, and on the problems of coherence, with the econometric model CHOIX

Structural characterization of humic acids, extracted from sewage sludge during composting, by thermochemolysis–gas chromatography–mass spectrometry

Thermochemolysis coupled with gas chromatography and mass spectrometry were applied to determine the structure of humic acids (HA) extracted from a sewage sludge and straw mixture at different steps of composting. The HA extracted from sludge mixture released various compounds, such as mono-, di-, tri-methoxy (alkyl) benzene and (alkyl) benzoic acids, which originated from lignin like derivatives of phydroxyphenyl, guiaicyl and syringyl units. In addition, other aromatic non-lignin derived structures were found along with series of branched C15, linear C16, C18 fatty acid methyl esters. The follow-up of various lignin-derived units during composting shows a decrease in phydroxyphenyl type-compounds (C) after the stabilisation phase. In parallel the more oxidized units, derived from guaiacyl (G) and syringyl (S) units, corresponding mainly to methylated derivatives of cafeic acids, protocatechuic acids, gallic acids and aldehydes, significantly increased in comparison with the other aromatic structures. Various ratios commonly used as parameters to determine the degree of lignin decomposition during humification were followed to monitor the chemical structure changes of the HA extracted from sludge mixture during composting. In the present case, the S/G ratio did not present significant changes during composting. The acid/aldehyde ratio was supervised using the ratio of gallic acids to gallic aldehyde methylated derivatives and showed an increase from 0.73 to 2.13 after the stabilisation phase but a decrease to 0.93 at the end of composting. This evolution may be explained by the increase of acid-containing derivatives following the intense oxidation of lignin side-chains during the stabilisation phase. But, the decrease of the acid/aldehyde ratio during the maturation phase could be attributed to a decrease in acid units by polymerisation of benzoic acid type-compounds through ester/ether linkages. The follow up of six families of compounds of similar chemical structures during composting showed a decrease of lignin-type compounds C6–C3 and that C6–C1 units predominated in the humic acid isolated from end compost sludge. The fatty acid methyl esters showed an increase in the intermediate phase of composting probably originating from the activities and tissues of microorganisms, which are numerous during the process. The final decrease in the amount of fatty acids may be explained by the death of most of the microbial population at the end of composting typified by a low respiratory rate. The index of Shannon-Weaver (Ish) remained constant at about 3 in course of composting indicating the neoformation of HA from subunits of similar chemical nature. A similitude index (Sij, S0 i j) showed a split between 30 and 90 days of composting indicating a change in the rate of neoformation of HA after a stabilisation phase. Afterwards, the rate of HA neoformation varied linearly with the duration of composting