Camps de concentration nazis | EPFL Graph Search

vignette|upright=1.5|Carte des camps de concentration nazis. Les camps de concentration nazis sont des centres de détention de grande taille créés par le Troisième Reich à partir de 1933 et jusqu'à la fin de la Seconde Guerre mondiale, pour interner, exploiter la force de travail et tuer des opposants politiques, des résidents d'un pays conquis, des groupes ethniques ou religieux spécifiques, etc. Ce sont les détenus qui sont forcés de construire ces camps, les victimes travaillant dans des conditions inhumaines, y laissant souvent leur vie. Le Troisième Reich utilisa les camps de concentration (en allemand : Konzentrationslager, abrégé en KL ou KZ), comme ceux de Dachau ou Buchenwald pour éloigner et terroriser les opposants politiques au régime, puis pour y interner les Juifs, les Tziganes, les prêtres et prélats catholiques, les Témoins de Jéhovah, les homosexuels et les « éléments asociaux » comme les criminels, vagabonds Après le déclenchement de la Seconde Guerre mondiale, ces

"Caldas do Viaduto". Population et territoire vieillissants de Beira Interior (PT)

Tania Depallens

Le Portugal et la région de Beira Interior possèdent l’une des populations les plus âgées du monde. Le pays a par ailleurs une longue histoire de littoralisation – concentration des populations, activités et réseaux d’infrastructure le long de la côte – laissant l’intérieur du pays défavorisé. Le projet revendique une nouvelle identité pour la Beira Interior, loin des représentations rurales et nostalgiques. La région possède des conditions hydrogéologiques qui en font une destination de thermalisme, soit l’usage d’eau thermale minérale à des fins thérapeutiques et récréatives. Ainsi, une vision holistique de la santé se lie à l’écologie de son paysage. Cette activité aquatique insiste sur le bien-être, recadrant le discours sur le vieillissement en termes d’habitabilité (qualité, prendre soin) plutôt que de durabilité (quantité, soigner). Le projet propose donc des bains thermaux, qui évoluent à partir d’une culture locale de la baignade et s’insèrent dans le développement d’un réseau existant de bains. La faille de Ponsul est à l’origine de sources thermales et de la formation des Portes de Ródão. Ces crêtes montagneuses produisent une impression d’isolement; elles forment, avec le fleuve du Tage et une ligne de train, les limites du site. Le projet propose un nouvel accès par bateau et train. Les bains thermaux grandissent du sol et se fondent dans le paysage, laissant le site paraître intact de toute intervention. La construction dialogue avec un viaduc de pierre existant où passe la ligne de train. Les bains sont à la fois un mur et une plateforme, un paysage et une infrastructure.

2018

Behaviour of carbon-14 containing low molecular weight organic compounds in contaminated groundwater under aerobic conditions

Aislinn Ann Boylan

Short chain carbon-14 (C-14) containing organic compounds can be formed by abiotic oxidation of carbides and impurities within nuclear fuel cladding. During fuel reprocessing and subsequent waste storage there is potential for these organic compounds to enter shallow subsurface environments due to accidental discharges. Currently there is little data on the persistence of these compounds in such environments. Four C-14-labelled compounds (acetate; formate; formaldehyde and methanol) were added to aerobic microcosm experiments that contained glacial outwash sediments and groundwater simulant representative of the Sellafield nuclear reprocessing site, UK. Two concentrations of each electron donor were used, low concentration (10(-5) M) to replicate predicted concentrations from an accidental release and high concentration (10(-2) M) to study the impact of the individual electron donor on the indigenous microbial community in the sediment. In the low concentration system only similar to 5% of initial C-14 remained in solution at the end of experiments in contact with atmosphere (250-350 h). The production of (CO2)-C-14(g) (measured after 48 h) suggests microbially mediated breakdown is the primary removal mechanism for these organic compounds, although methanol loss may have been partially by volatilisation. Highest retention of C-14 by the solid fractions was found in the acetate experiment, with 12% being associated with the inorganic fraction, suggesting modest precipitation as solid carbonate. In the high concentration systems only similar to 5% of initial C-14 remains in solution at the end of the experiments for acetate, formate and methanol. In the formaldehyde experiment only limited loss from solution was observed (76% remained in solution). The microbial populations of unaltered sediment and those in the low concentration experiments were broadly similar, with highly diverse bacterial phyla present. Under high concentrations of the organic compounds the abundance of common operational taxonomic units was reduced by 66% and the community structure was dominated by Proteobacteria (particularly Betaproteobacteria) signifying a shift in community structure in response to the electron donor available. The results of this study suggest that many bacterial phyla that are ubiquitous in near surface soils are able to utilise a range of C-14-containing low molecular weight organic substances very rapidly, and thus such substances are unlikely to persist In aerobic shallow subsurface environments.

ELSEVIER SCI LTD2018

Production, characterization and upgrading of biomass-derived acetal-stabilized carbohydrates

Ydna Marie Questell-Santiago

Biomass is an attractive source of renewable carbon-based fuels and chemicals. Multiple research efforts are centered around integrated biorefineries, where all fractions of biomass are converted to fuels or chemical products. These efforts are focused around making biorefineries more economically competitive and sustainable. One of the major drawbacks is the incomplete utilization of biomass, specifically, lignocellulosic biomass, which is the largest terrestrial source of renewable carbon. Given the significant differences in the structure and reactivity of its components, the integrated depolymerization and subsequent upgrading of all the fractions involved has been challenging. The depolymerization of lignocellulosic biomass is controlled by the kinetic competition between depolymerization and degradation reactions. Multiple strategies have relied in the modification of reaction conditions to mitigate this limitation, but are either expensive or have not fully overcome this issue. Here, I present the use of protecting group chemistry to reversibly stabilize biomass-derived carbohydrates during depolymerization by acetal formation with formaldehyde (FA). This stabilization technique, altered the kinetic paradigm by limiting sugar dehydration and further degradation. The depolymerization of beech wood using acid organosolv processes in the presence of FA led to recoveries of over 90% sugars with a final concentration of ~5wt%. The produced acetal-stabilized biomass-derived sugars possess versatile properties compared to unmodified sugars, which motivated me to further investigate their reactivity. I found that diformylxylose (acetal-stabilized xylose, DX) produced an intermediate during its acid hydrolysis deprotection that promoted a 1,2-hydride shift that led to the low temperature production of furfural. Generally, this shift is catalyzed by Lewis acids, but its presence did not affect the rate of reaction when DX was used as a starting material. Based on these findings and Operando NMR studies, a tandem hydrolysis-dehydration of DX to furfural, was pro-posed. The benefits of using acetal-stabilized sugars was studied by performing a preliminary techno-economic analysis for the non-enzymatic production of ethanol and the direct upgrading of DX to xylitol. After taking account the solvent savings and the extra recovery steps of FA, a minimum selling price of

4.05 (

2014) of gasoline gallon equivalent was calculated. In the case of xylitol production, a proposed process was constructed around the volatility and unique reactivity of DX. The key advantages included the purification potential of DX by distillation rather than activated carbon adsorption and ion exchange chromatography, which is used for xylose purification, and a rate limiting step that was independent of hydrogen pressure, which minimized hydrogen requirements. The on stream study of the catalyst demonstrated an evolution of the active sites of Pt that led to an enhanced xylitol yield. This phenomenon is attributed to the formation of Pt(OH)2 (detected by X-ray photoelectron spectroscopy), which accelerates the hydrolysis and hydrogenation reactions due to the proximal acid site to Pt0. In overall, I have demonstrated that acetal functionalization of carbohydrates can, not only increase yields by reducing sugar degradation but also reveal new reactivity that can be exploited to create novel catalytic upgrading pathways for the production of bio-based chemicals.

EPFL2019