Search results for "recycling"
showing 10 items of 207 documents
Moving forward sustainably : material and social conditions of electronic waste management in Nigeria
2018
This dissertation focuses on understanding the social material interaction between e-waste and e-scrappers for sustainable management of e-waste. Previous studies mainly concentrate on the detrimental environmental impact of e-scrappers activities, the economic and political influences of e-waste on the e-scrappers, the material flow of e-waste and the exportation of valuable e-waste extracts from highly industrialized countries to less industrialized countries. The aim of the dissertation is therefore to extend the scope of the previous studies by investigating the social material interaction between e-scrappers and e-waste. To achieve this aim, this study examines the following research q…
Daidzein has neuroprotective effects through ligand-binding-independent PPARγ activation.
2011
Phytoestrogens are a group of plant-derived compounds that include mainly isoflavones like daidzein. Phytoestrogens prevent neuronal damage and improve outcome in experimental stroke; however, the mechanisms of this neuroprotective action have not been fully elucidated. In this context, it has been postulated that phytoestrogens might activate the peroxisome proliferator-activated receptor-γ (PPARγ), which exerts neuroprotective effects in several settings. The aim of this study was to determine whether the phytoestrogen daidzein elicits beneficial actions in neuronal cells by mechanisms involving activation of PPARγ. Our results show that daidzein (0.05-5 μM) decreases cell death induced b…
Development of energy-saving innovative hydraulic mortars reusing spent coffee ground for applications in construction
2023
This paper reports the development of green bio-composite mortars, obtained reusing spent coffee ground (SCG), an agri-food residue, in the light of the Circular Economy approach. This process can boost the sustainability in Construction and proposes an alternative to SCG disposal in landfill, potentially dangerous to humans and the environment. For the first time, specimens were produced and compared using different blends of conventional hydraulic binders (ordinary Portland cement and natural hydraulic lime); SCG partially substituted sand (up to 15 wt.%, with a 2.5% increment) for the aggregate mix. The manufacturing process was performed at ambient conditions (20°C, 65% RH) resulting hi…
The heterogeneity of the Mexican lithospheric mantle: Clues from noble gas and CO2 isotopes in fluid inclusions
2022
The abundance of mantle-derived rocks and lavas, in combination with its tectonic evolution, render Mexico a perfect laboratory to investigate the chemical and the isotopic heterogeneity of the lithospheric mantle. New data on the composition of noble gases and CO2in Mexican mantle xenoliths and lavas is reported. Our samples consist of six ultramafic nodules from the Durango Volcanic Field (DVF) and the San Quintin Volcanic Field (SQVF), monogenetic complexes belonging to the Mexican Basin and Range province; and four lavas from the Sierra Chichinautzin (SCN), a Quaternary monogenetic volcanic field located in the Mexican volcanic arc. Ne and Ar isotopes in fluid inclusions reveal mixing b…
Eastern Ancient Terrane of the North China Craton
2016
Based on the spatial distribution of ancient rocks and zircons, three ancient terranee older than ca. 2.6 Ga have recently been identified in the North China Craton, namely the Eastern, Southern, and Central Ancient Terranee. The Eastern Ancient Terrane is the best studied and understood of the three ancient terranes. It has a long geological history back to ca. 3.8 Ga ago and includes the areas of Anshan-Benxi, eastern Hebei, eastern Shandong and western Shandong. In Anshan-Benxi, several different types of 3.8 Ga rocks were discovered together with 3.1–3.7 Ga rocks, whereas 2.9–3.0 Ga K-rich granites and 2.5 Ga syenogranite occur on larger scales. In eastern Hebei, 3.0–3.4 Ga rocks and ol…
Generation of early Archaean grey gneisses through melting of older crust in the eastern Kaapvaal craton, southern Africa
2014
Abstract We report zircon ages, Hf-in-zircon isotopes as well as whole-rock geochemistry and Hf–Nd isotopic systematics for Palaeoarchaean grey gneisses of the Ancient Gneiss Complex of Swaziland, the oldest components of the Kaapvaal craton, southern Africa. The Hf-in-zircon isotopic compositions in these compositionally heterogeneous, multicomponent, migmatitic gneisses are highly variable, even in the oldest zircons dating back to 3.66 Ga, suggesting growth of zircon from melts representing a mix of juvenile and anatectic material derived from differentiated continental crust of Eoarchean to late Hadean age. In contrast, the initial Nd and Hf whole-rock isotopic compositions are frequent…
Palaeozoic arc magmatism in the Central Asian Orogenic Belt of Kazakhstan: SHRIMP zircon ages and whole-rock Nd isotopic systematics
2008
Abstract Early Palaeozoic tonalite to granodiorite intrusions in northern Kazakhstan are associated with lode gold mineralization and have SHRIMP zircon ages of 457.3 ± 6.6 Ma (Aksu), 452.9 ± 5.6 Ma and 447.4 ± 5.4 Ma (both Zholymbet). The Stepnyak intrusion contains large xenoliths with an age of 480.6 ± 5.0 Ma. One early Palaeozoic zircon from a porphyritic diorite at Stepnyak has a core with a near-concordant 207Pb/206Pb age of 3888 ± 1.5 Ma, whereas other xenocrystic grains are between 983 and 2698 Ma old. The early Archaean age is probably inherited from unexposed basement of the Kokchetav Massif and represents the oldest crustal material so far known from the Asian continent. It appea…
Numerical modelling of PT-paths related to rapid exhumation of high-pressure rocks from the crustal root in the Variscan Erzgebirge Dome (Saxony/Germ…
2002
Abstract The Bohemian Massif in the Central European Variscides contains many crustal slices with (ultra-)high-pressure rocks related to continent-continent collision. After closure of pre-existing oceans during the Devonian, excess crustal thickness was maintained for about 50 Ma until at around 340 Ma large volumes of high-pressure rocks from the crustal root were exhumed within a few million years. We relate this event to delamination and complete detachment of the lithospheric mantle, causing a crustal-scale isostatic instability. In the Erzgebirge dome, a model region in the northern part of the massif, an array of interrelated PTtd-paths with “decompression/cooling” and “decompression…
Andean Cenozoic volcanic centers reflect basement isotopic domains
1992
Isotopic data for Quaternary volcanic centers from lat 17.5° to 22°S in northern Chile provide evidence for crustal contributions to arc magma genesis in the central Andes and delineate basement domains. Crustal thickness, distance from trench, height of volcanic edifices above the seismically active subduction zone, and sediment supply to the trench are all constant along this segment of the arc. The only significant variable is crustal age (Paleozoic in the south, Proterozoic in the north). Pb isotopic compositions of Quaternary lavas in the northern sector are lower ( 206 Pb/ 204 Pb = 17.89-18.28) and Sr and O isotope ratios are less variable ( 87 Sr/ 86 Sr = 0.7058-0.7077, δ 18 O = +6.5…
Recycling and transport of continental material through the mantle wedge above subduction zones: A Caribbean example
2016
Abstract Estimates of global growth rates of continental crust critically depend upon knowledge of the rate at which crustal material is delivered back into the mantle at subduction zones and is then returned to the crust as a component of mantle-derived magma. Quantification of crustal recycling by subduction-related magmatism relies on indirect chemical and isotopic tracers and is hindered by the large range of potential melt sources (e.g., subducted oceanic crust and overlying chemical and clastic sediment, sub-arc lithospheric mantle, arc crust), whose composition may not be accurately known. There is also uncertainty about how crustal material is transferred from subducted lithosphere …