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

Comparing the cost-effectiveness of two- and three-dose schedules of human papillomavirus vaccination: a transmission-dynamic modelling study.

BACKGROUND: Recent evidence suggests that two doses of HPV vaccines may be as protective as three doses in the short-term. We estimated the incremental cost-effectiveness of two- and three-dose schedules of girls-only and girls & boys HPV vaccination programmes in Canada. METHODS: We used HPV-ADVISE, an individual-based transmission-dynamic model of multi-type HPV infection and diseases (anogenital warts, and cancers of the cervix, vulva, vagina, anus, penis and oropharynx). We conducted the analysis from the health payer perspective, with a 70-year time horizon and 3% discount rate, and performed extensive sensitivity analyses, including duration of vaccine protection and vaccine cost. FINDINGS: Assuming 80% coverage and a vaccine cost per dose of $85, two-dose girls-only vaccination (vs. no vaccination) produced cost/quality-adjusted life-year (QALY)-gained varying between$7900-24,300. The incremental cost-effectiveness ratio of giving the third dose to girls (vs. two doses) was below $40,000/QALY-gained when: (i) three doses provide longer protection than two doses and (ii) two-dose protection was shorter than 30 years. Vaccinating boys (with two or three doses) was not cost-effective (vs. girls-only vaccination) under most scenarios investigated. INTERPRETATION: Two-dose HPV vaccination is likely to be cost-effective if its duration of protection is at least 10 years. A third dose of HPV vaccine is unlikely to be cost-effective if two-dose duration of protection is longer than 30 years. Finally, two-dose girls & boys HPV vaccination is unlikely to be cost-effective unless the cost per dose for boys is substantially lower than the cost for girls

Récupération de métaux nobles sous forme de nanoparticules par traitement plasma à barrière diélectrique

Les métaux du groupe du platine (MGP) et les métaux nobles sont utilisés dans des secteurs industriels reliés aux catalyseurs automobiles, aux matériaux semi-conducteurs et même en médecine régénératrice. L’extraction ce ces métaux à partir de minerais et d’effluents est réalisée par divers procédés hydrométallurgiques, tels que la lixiviation et l’adsorption sur charbon activé. Ces procédés sont associés à plusieurs problématiques : les temps de production sont longs, l’extraction sélective des éléments d’intérêt nécessite des produits toxiques (e.g. cyanures) et l’utilisation de charbon activé est à l’origine de l’émission de gaz à effet de serre (GES). La demande croissante pour ces métaux motive le développement de nouvelles technologies permettant de les récupérer plus rapidement et efficacement, tout en minimisant l’impact environnemental de leur production. Les plasmas atmosphériques produits par décharge à barrière diélectrique (DBD) font partie des technologies novatrices qui permettraient de s’affranchir des désavantages reliés aux procédés de récupération conventionnels. En seulement quelques minutes, le traitement des effluents contenant des ions métalliques par l’application de décharges plasmas permet la récupération des métaux nobles sous forme de nanoparticules (NPs). Ce mémoire présente cette technique de récupération plasma appliquée à des effluents synthétiques, miniers, industriels et hospitaliers. En moins de 15 min d’opération, un réacteur plasma DBD permet de récupérer sélectivement 95% de l’or pour des effluents provenant des industries minières et des semi-conducteurs. Cette technologie présente également un potentiel pour la récupération du palladium, qui atteint 60% et ce pour des conditions pouvant être optimisées davantage. De plus, les réactions électrochimiques induites par les décharges plasma sont en mesure de dégrader des contaminants hautement toxiques tels que les cyanures. Ces résultats prometteurs ont motivé la prise de démarches pour implémenter cette technologie à l’échelle industrielle chez différentes compagnies partenaires du domaine minier et des semiconducteurs.Platinum group metals (PGMs) and noble metals are used in industrial fields related to automotive catalysts, semiconductor materials and even regenerative medicine. The extraction of these metals from ores and effluents is performed by various hydrometallurgical processes, such as leaching and activated carbon adsorption. These processes are associated with several problems: the production times are long, the selective extraction of the elements of interest requires toxic products (e.g. cyanides) and the use of activated carbon is responsible for the emission of greenhouse gases (GHG). The growing demand for these metals stimulates the development of new technologies to recover them more quickly and efficiently, while minimizing the environmental impact of their production. Atmospheric plasmas produced by dielectric barrier discharge (DBD) are among the innovative technologies that can overcome disadvantages related to the conventional recovery processes. In a matter of minutes, the treatment of effluents containing metal ions by the application of plasma discharges allows the recovery of noble metals in the form of nanoparticles(NPs). This thesis presents this recovery technique applied to synthetic, mining, industrial and hospital effluents. In less than 15 min of operation, a DBD plasma treatment can be used to selectively recover 95% of gold from effluents produced by mining and semiconductor industries. This technology also has potential for the recovery of palladium, which reaches 60% for conditions that could be further optimized. Moreover, the electrochemical reactions induced by the plasma discharges can degrade highly toxic contaminants such as cyanides. These promising results stimulated the first steps for the implementation of this technology to the industrial scale in collaboration with various partner companies from the mining and semi-conductor fields

Transformation by plasma technology of cisplatin found in hospital's wastewaters into platinum-containing nanoparticles

Platinum-containing molecules such as cisplatin figure among oncology's most widely used antineoplastic agents. Cisplatin excreted in the urine usually ends up in municipal wastewater, with a strong toxicological and carcinogenic impact on the environment. Thus, cisplatin should be inactivated before reaching wastewater to attenuate its environmental impact. However, conventional recommended procedures use large quantities of toxic acids, which are not sustainable processes. In this study, a dielectric barrier discharge (DBD) atmospheric pressure plasma reactor is used to degrade cisplatin in wastewater, allowing platinum's recuperation. The article describes the plasma discharge (power, electron temperature, and density) and confirms the most stable operation parameters under Ar and Ar+H2 discharges. Cisplatin is diluted in water or synthetic urine, and plasma treatment is conducted for 30 min. The process degrades cisplatin molecules by conversion into platinum-rich nanoparticles (NPs). These nanoparticles are efficiently recuperated by centrifugation and are characterized by transmission electron microscopy and X-ray photoelectron spectroscopy (XPS). The mass-balance assessment confirms that more than 90% of cisplatin is degraded and recuperated as Pt-rich NPs

Le rôle des infrastructures naturelles pour la gestion des eaux de ruissellement et des crues dans un contexte d’adaptation aux changements climatiques

Cet article présente une recension des écrits sur les infrastructures naturelles (IN) comme moyen d’adaptation aux changements climatiques, en prenant pour exemple la gestion des eaux de ruissellement et des crues. Une revue d’études de cas permet d’apprécier le potentiel des IN comme solution de rechange aux approches reposant sur des infrastructures conventionnelles dites grises. En effet, les approches d’aménagement du territoire urbain et périurbain qui intègrent les IN valorisent la production de services écosystémiques afin d’améliorer la résilience des villes et l’adaptation aux changements climatiques, avec comme objectif ultime de trouver des solutions durables et efficaces aux nouvelles conditions climatiques. Cet article propose des balises conceptuelles afin de mieux évaluer le potentiel des IN et la faisabilité de leur mise en oeuvre. Nous présentons une revue de cas d’implantation d’IN en regard de leur rapport coût-efficacité, de leur résilience et de leur capacité à concilier des intérêts souvent divergents entre les sphères sociales, économiques et environnementales.This article provides a review of the literature on the use of green (or natural) infrastructures (GIs) as a means of adapting to climate change, using runoff and flood management as examples. An analysis of case studies assesses the potential of GIs to serve as alternatives to methods based on conventional grey infrastructures. Urban planning approaches that integrate GIs, recognise and value ecosystem services as a means of improving urban resilience and adaptation to climate change. The ultimate objective of this approach is to find sustainable and effective solutions to modified climatic conditions. This article proposes a conceptual framework to evaluate the potential of GIs and the feasibility of putting them into practice, and a case study review of the implementation of GIs in terms of their cost-effectiveness, resilience and capacity to reconcile often divergent social, economic and environmental interests is presented

Avenir du métier de bibliothécaire (L\u27)

Table ronde sur l\u27avenir du métier de bibliothécaire, à l\u27occasion du Salon du livre de 1999. Approche comparée France/Québec Document numérisé à l\u27occasion des 20 ans de l\u27enssib

Marennine, Promising Blue Pigments from a Widespread Haslea Diatom Species Complex

In diatoms, the main photosynthetic pigments are chlorophylls a and c, fucoxanthin, diadinoxanthin and diatoxanthin. The marine pennate diatom Haslea ostrearia has long been known for producing, in addition to these generic pigments, a water-soluble blue pigment, marennine. This pigment, responsible for the greening of oysters in western France, presents different biological activities: allelopathic, antioxidant, antibacterial, antiviral, and growth-inhibiting. A method to extract and purify marennine has been developed, but its chemical structure could hitherto not be resolved. For decades, H. ostrearia was the only organism known to produce marennine, and can be found worldwide. Our knowledge about H. ostrearia-like diatom biodiversity has recently been extended with the discovery of several new species of blue diatoms, the recently described H. karadagensis, H. silbo sp. inedit. and H. provincialis sp. inedit. These blue diatoms produce different marennine-like pigments, which belong to the same chemical family and present similar biological activities. Aside from being a potential source of natural blue pigments, H. ostrearia-like diatoms thus present a commercial potential for aquaculture, cosmetics, food and health industries