Recovery of noble metal elements from effluents of the semiconductor industry as nanoparticles, by dielectric barrier discharge (DBD) plasma treatment

The fabrication of semiconductor products for the microelectronic industry requires the deposition of thin noble metal layers (e.g. Au-Sn and Pd) by means of processes involving fluid baths that contain metal ions (e.g. electrowinning and electroless plating). After several cycles, the plating solutions are used up and must be replaced, generating large volumes of discarded solutions containing precious metals. The metals (Au and Pd) are recovered either by electrowinning, a slow batch process, or by the use of toxic molecules (e.g. cyanides). This study demonstrates the possibility of using an atmospheric plasma technology to recover Au and Pd from these solutions, which provides a faster and greener process. Plasma discharges are generated at the surface of the solutions, causing ions to precipitate as nanoparticles. The treatment (few minutes only) allows the recovery of >95% gold, and >60% palladium. The process separates Au (NPs) from Sn ions (remaining in solution), as confirmed by elemental analysis and XPS. Particle size distributions of the nanoparticles recovered through the process suggests that as- synthesized nanoparticles could integrate value-added products (e.g. catalyst industry). Overall, the use of plasma technology could open several possibilities for the recycling of metals contained in solutions discarded from the semiconductor industry

Les fins d’emploi de carrière et les emplois de transition vers la retraite selon la profession au Canada, 2002 à 2007

Le vieillissement de la main-d’œuvre canadienne entraîne diverses conséquences sur le marché du travail et sur les parcours de fin de vie active. C’est pourquoi cette recherche s’intéresse à la problématique des fins d’emploi de carrière et du passage vers un emploi de transition vers la retraite. À l’aide des données longitudinales de l’Enquête sur la dynamique du travail et du revenu de 2002 à 2007, l’objectif est de mener une analyse descriptive de cette trajectoire selon la profession, ce qui ne semble jamais avoir été fait dans la littérature canadienne. Les résultats montrent que certaines professions ont enregistré proportionnellement plus de fins d’emploi de carrière durant cette période, dont les enseignants et les occupants d’un poste de direction. Des analyses supplémentaires ont calculé la part des travailleurs ayant effectué leur transition dans une profession différente.In Canada, the ongoing aging of the labour force has direct effects on the labour market and the way workers live their transition to retirement. Thus many believe in the importance of studying the lifecourse of older workers. Using longitudinal data from the Survey of Labour and Income Dynamics, this study analyzes the older workers who left a career job between 2002 and 2007, and looks at their subsequent labour market activity in order to know if some of them entered a bridge job. This research focuses on occupational differences for the first time in the Canadian literature. In proportion, the results show higher than average rates of leaving their career job in some specific occupations, especially teachers and managers. Moreover this study aims to measure the proportion of older workers who found a bridge job in a different occupation

Magnetic resonance imaging of human tissue-engineered adipose substitutes

Adipose tissue (AT) substitutes are being developed to answer the strong demand in reconstructive surgery. To facilitate the validation of their functional performance in vivo, and to avoid resorting to excessive number of animals, it is crucial at this stage to develop biomedical imaging methodologies, enabling the follow-up of reconstructed AT substitutes. Until now, biomedical imaging of AT substitutes has scarcely been reported in the literature. Therefore, the optimal parameters enabling good resolution, appropriate contrast, and graft delineation, as well as blood perfusion validation, must be studied and reported. In this study, human adipose substitutes produced from adipose-derived stem/stromal cells using the self-assembly approach of tissue engineering were implanted into athymic mice. The fate of the reconstructed AT substitutes implanted in vivo was successfully followed by magnetic resonance imaging (MRI), which is the imaging modality of choice for visualizing soft ATs. T1-weighted images allowed clear delineation of the grafts, followed by volume integration. The magnetic resonance (MR) signal of reconstructed AT was studied in vitro by proton nuclear magnetic resonance (1H-NMR). This confirmed the presence of a strong triglyceride peak of short longitudinal proton relaxation time (T1) values (200±53 ms) in reconstructed AT substitutes (total T1=813±76 ms), which establishes a clear signal difference between adjacent muscle, connective tissue, and native fat (total T1 ∼300 ms). Graft volume retention was followed up to 6 weeks after implantation, revealing a gradual resorption rate averaging at 44% of initial substitute's volume. In addition, vascular perfusion measured by dynamic contrast-enhanced-MRI confirmed the graft's vascularization postimplantation (14 and 21 days after grafting). Histological analysis of the grafted tissues revealed the persistence of numerous adipocytes without evidence of cysts or tissue necrosis. This study describes the in vivo grafting of human adipose substitutes devoid of exogenous matrix components, and for the first time, the optimal parameters necessary to achieve efficient MRI visualization of grafted tissue-engineered adipose substitutes

High sensitivity detection of nanoparticles permeation through polymer membranes: A physico-chemical and nuclear imaging measurement approach

Diffusion cells are devices made of donor and acceptor compartments (DC and AC), separated by a membrane. They are widely used in pharmaceutical, cosmetic, toxicology, and protective equipment tests (e.g., gloves) to measure the kinetics of permeants (molecules and nanoparticles) across biological membranes as the skin. However, rarely is the concentration of permeants in the AC measured in continuous or in real-time, and this limitation leads to significant discrepancies in the calculations of kinetic parameters that define the permeation mechanisms. In this study, a diffusion cell compatible with positron emission tomography was used to measure the permeation kinetics of nanoparticles across glove membranes. The technology allows for the measurement of nanoparticle concentration in real-time in the two compartments (DC and AC) and at a detection sensitivity several orders of magnitude higher compared with conventional spectroscopies, thus allowing a much more precise extraction of kinetic parameters. Ultra-small (<10 nm) gold nanoparticles were used as a model nanoparticle contaminant. They were radiolabeled, and their diffusion kinetics was measured in continuous through latex and nitrile polymer membranes. Permeation profiles were recorded at sub-nanomolar sensitivity and in real-time, thus allowing the high precision extraction of kinetic permeation parameters. The technology, methodology, and data extraction process developed in this work could be applied to measure in real-time the kinetics of diffusion of a whole range of potentially toxic molecules and nanoparticles across polymer membranes, including glove membranes

Enjeux théoriques et pratiques du développement régional : 30 Ans de recherche au GRIR

Le trentième anniversaire du GRIR a été souligné au printemps 2013 par un colloque regroupant plusieurs chercheurs dans le domaine du développement local et régional. Cet ouvrage est le produit de leurs réflexions tant sur le plan théorique que pratique. Ce livre est articulé autour de trois axes : 1) la présentation des divers courants en développement régional, 2) des réflexions sur le passé et le présent des Premières Nations et 3) la présentation de cas concrets sur la prise en main du développement par les différents acteurs du territoire. Cet ouvrage est un outil permettant de constater le travail accompli en développement local et régional et de dégager des pistes de réflexion sur les avenues possibles de développement

The measurement of ancestral roots with genealogical data

This study presents a new method to measure the depth of ancestral roots in a population. This method sheds light on the migratory movements which led to present-day population distribution across space. The method was applied to a dataset of 5,100 ascending genealogies from seventeen regions of the province of Quebec (Canada). Dates of marriage of the earliest ancestors married in the same region as their descendants were used to measure the age of individual ancestral roots. The average regional ages vary between 16 and 157 years, while some individual roots reach as far back as 300 years in the same region. The proposed method can be useful for assessing how deeply rooted a contemporary population is at a local, regional or other geographical level

CD47 fusion protein targets CD172a+ cells in Crohn’s disease and dampens the production of IL-1β and TNF

In mice, the transfer of CD172a(+) (SIRP-α) dendritic cells (DCs) elicits T cell–driven colitis, whereas treatment with CD47-Fc protein, a CD172a-binding agent, confers protection. The aim of this study was to elucidate the nature and functional properties of human CD172a(+) DCs in chronic intestinal inflammation. Here, we show that CD172a(+)CD11c(+) cells accumulate in the mesenteric lymph nodes (mLNs) and inflamed intestinal mucosa in patients with Crohn’s disease (CD). These cells are distinct from resident DCs and may coexpress markers typically associated with monocyte-derived inflammatory DCs such as CD14 and/or DC-SIGN, E-Cadherin, and/or CX(3)CR1. Spontaneous IL-1β and TNF production by HLA-DR(+) cells in CD tissues is restricted to those expressing CD172a. An avidity-improved CD47 fusion protein (CD47-Var1) suppresses the release of a wide array of inflammatory cytokines by CD172a(+) cells, which may include HLA-DR(−)CD172a(+) neutrophils, in inflamed colonic explant cultures and impairs the ability of HLA-DR(+)CD172a(+) cells to activate memory Th17 but not Th1 responses in mLNs. In conclusion, targeting CD172a(+) cells may represent novel therapeutic perspectives for patients with CD