1,383,172 research outputs found
In Search of Common Ground, Reflections on articulating concepts and theoretical orientations in CERES
No full textThe board and directorate of CERES research school have initiated a synthesizing study of the various research programmes and projects which are part of the school. The objective was first of all to construct an overview of the variety of research questions and topics that are being studied by CERES researchers. On the basis of this overview our task has been to deduct the main lines or common ground within this wide variety of research projects and interests focusing particularly on concepts which emerge from the various research interests and demonstrate a capacity to bring together various research lines and working programmes. In this respect we use the terms articulating or clustering concepts. Our aim was furthermore to bring together and develop these concepts into a framework which reflects the common ground of CERES research. This common ground may guide ongoing and future development of CERES and clarify the identity and positioning of the schoo
IXIM: A new maize simulation model for DSSAT v4.5.
No full textThe Decision Support System for Agrotechnology Transfer (DSSAT) is a suite of crop simulation models and associated tools for simulating growth, development, and yield of 25 crops. The maize simulation model in DSSAT is CSM-CERES, the modular version of CERES-Maize, which was first published in 1986. The newest release of DSSAT, version 4.5, provides users with the opportunity to run an alternative maize simulation model. IXIM (eeh-sheem), the Mayan language for maize, is a new, more mechanistic, maize simulation model fully compatible with DSSAT. The purpose of this work is to compare seasonal simulations of maize growth and N uptake using CSM-CERES and IXIM
CEReS Deliverable 4.1: Char Leaching Reactor Type
No full textWork Package 4 Char Leaching aims to demonstrate the feasibility for utilisation of the acidic leachates (biolixiviant) generated from coal wastes bioleaching (Work Package 3) as leaching agent for extraction of the base and high-value metals contained in the char originating from the pyrolysis of PCB’s (Work Package 2). The challenge of this Work Package is to find or design the suitable reactor for treating such material, which is unique compared to conventional materials treated in (bio)hydrometallurgy reactors, e.g. mineral ores, PCBs, etc.
Stirred-tank reactor (STR) is the most commonly employed since the early days of biohydrometallurgy campaigns, ranging from lab-scale to industries, treating mineral ores to electronic wastes and residues. The main advantage of this type of reactor is the achievement of the desired levels of mass transfer, mixing, and suspension, in which STR outperforms other types of reactor. Due to that, STR has been given priority during Work Package 4 of CEReS project.
Despite the advantages, STR faces the problem of char’s special physical characteristics. The disintegration of fibres followed by their suspension inside reactor needs a careful hydrodynamic design to maintain sustained mixing and mass transfer. Moreover, the high shear stress of impeller rotation may harm the presence of biofilm, risking the elimination of microorganisms from the biolixiviant. As an alternative, leaching performance on rotary-drum reactor (RDR) has also been studied in this work package.Co-processing of coal mine and electronic wastes: Novel resources for a sustainable future (CEReS
A DITADURA DA MAGREZA
No full textCERES – Sua tese de doutorado versou sobre a análise de composição corporal, da densidade mineral óssea, da taxa metabólica de repouso e da ingestão alimentar de modelos residentes na cidade de São Paulo. Poucas destas análises apontaram diferenças entre adolescentes modelos e não-modelos. Você acha que o tempo em que as adolescentes estão nessa rotina possa ter influenciado nos resultados?Alexandra - Realmente. De todas as análises feitas, o que mais nos chamou a atenção foi a ingestão calórica inferior entre as modelos (± 1.500kcal), em relação às adolescentes não-modelos (± 2.000kcal), além de uma ingestão menor de ferro e zinco entre as modelos.Ao fazer o estudo, optamos por avaliar adolescentes com mais de 15 anos e que já tinham tido a menarca há mais de dois anos. E fizemos essa escolha porque, em estudos anteriores, vimos que as adolescentes mais velhas apresentavam peso mais baixo e risco de desenvolver transtornos alimentares. Deve-se ressaltar que temos estudado principalmente modelos adolescentes, ou seja, de 10 a 19 anos e, portanto, no momento não temos dados das modelos na idade adulta, embora o Projeto Saúde Modelo atenda a todas as modelos, independentemente da idade. Não temos dados sobre como o tempo de profissão influencia no estado nutricional e sáude desse grupo, mas este está sendo nosso foco de estudo atualmente.
The missing large impact craters on Ceres
No full textabstract: Asteroids provide fundamental clues to the formation and evolution of planetesimals. Collisional models based on the depletion of the primordial main belt of asteroids predict 10–15 craters >400 km should have formed on Ceres, the largest object between Mars and Jupiter, over the last 4.55 Gyr. Likewise, an extrapolation from the asteroid Vesta would require at least 6–7 such basins. However, Ceres’ surface appears devoid of impact craters >∼280 km. Here, we show a significant depletion of cerean craters down to 100–150 km in diameter. The overall scarcity of recognizable large craters is incompatible with collisional models, even in the case of a late implantation of Ceres in the main belt, a possibility raised by the presence of ammoniated phyllosilicates. Our results indicate that a significant population of large craters has been obliterated, implying that long-wavelength topography viscously relaxed or that Ceres experienced protracted widespread resurfacing.The final version of this article, as published in Nature Communications, can be viewed online at: https://www.nature.com/articles/ncomms1225
CEReS Deliverable 4.3: Extractive Metallurgy Unit Development Report
No full textWP4 Char Leaching aims to demonstrate the feasibility for utilisation of the acidic leachates (biolixiviant) generated from coal wastes bioleaching (WP3) as leaching agent for extraction of the base and high-value metals contained in the char originating from the pyrolysis of PCB’s (WP2). The main tasks of this WP consist of three components: 1) investigation on the suitable reactor design and its working parameters for treating such material, which is unique compared to conventional materials treated in (bio)hydrometallurgy reactors, e.g. mineral ores, PCBs, etc., 2) exploring the option to extract metal(s) of interest and recover it/them to obtain a high-purity product, and 3) exploring the option to valorise the residue and excess iron in the char treatment system.
Stirred-tank reactor (STR) is the most commonly employed since the early days of biohydrometallurgy campaigns, ranging from lab-scale to industries, treating from mineral ores to electronic wastes and residues. The main advantage of this type of reactor is achieving the desired levels of mass transfer, mixing, and agitation, in which STR outperforms other types of reactors. Due to that, STR has been given priority during WP4 of CEReS project.
Despite the advantages, STR faces the challenge linked to the char’s special physical characteristics. The disintegration of fibres followed by their suspension inside reactor needs a careful hydrodynamic design to maintain sustained mixing and mass transfer. Moreover, the high shear stress of impeller rotation may harm the presence of biofilm, risking the elimination of microorganisms from the biolixiviant. As an alternative, leaching performance of rotary-drum reactor (RDR) has also been studied in this WP4. Step-leaching has also been studied in order to outline the possibility to increase the kinetic rate of copper dissolution by doing the leaching in several successive steps.
Different from mineral ores, char (or pyrolyzed PCBs) contains various metals and elements, oftentimes in high grades. More often than not, the leaching of the char is non-selective, meaning that other than metals of interest, the un-desired ones should also be dissolved at high concentration. This is proven to be problematic for recovery stage, thus highlight the importance of extraction stage as intermediate between leaching and recovery.
The solvent extraction stage consists of two steps; extraction step to transfer metal ions from solution (aqueous) to extractant (organic), and stripping step to transfer metal ions back from organic to aqueous. Concentrated metal ions in the aqueous phase are then transferred to recovery stage to produce metal product with high purity. This report will subsequently summarize the result on investigation of solvent extraction to produce concentrated electrolyte solution, followed by the results on recovery stage by electrowinning to produce metal product.
The treatment of residues came after the char leaching and solvent extraction-electrowinning occurred. The residue from char leaching still contains fairly high grade of precious metals (gold, silver) as well as platinum group metals (PGMs). Although the processing of such by-products is not in the scope of CEReS, the possibility of such treatment has been explored in relation to CEReS applying the concept of biohydrometallurgy. The bleeding of iron from the system is important to maintain balanced level of accumulative iron from overall process, and has been explored by performing jarosite precipitation.Co-processing of coal mine and electronic wastes: Novel resources for a sustainable future (CEReS
Fresh fruit and vegetables: a world of multiple interactions : the case of the Buenos Aires Central Wholesale Market (BACWM)
No full textThis research explores ethnographically the everyday social interactions between the ‘users’ of a particular marketplace, the Buenos Aires Central Wholesale Market (BACWM). The ‘users’ of this marketplace are the social actors who work there everyday, and who bring and buy fresh produce. These ´users´ are the ´makers´ of the BACWM since, through their everyday practices, interactions and interpretations and knowledge, they socially construct this hub of distribution
The global social problem : challenges for a Research School like CERES
No full textThe text starts with a reminder of the historical roots of the debate about the social problem in early industrial England, and connects it with the current debate about social exclusion and poverty, with an example from South Africa. Poverty issues should be related to the debates about labour conditions and labour rewards and about the variety of capitalist transformations taking place in the era of globalisation and of global social polarisation. But understanding poverty also demands a multi-facetted approach, with attention for images of poverty in a comparative cultural perspective. As a research school CERES regards it as the core of her work. The inaugural lecture ends with twelve points for action in CERES and reminds us of the current relevance for our work of the old myths around the Goddess CERES. May she protect us
CEReS Deliverable 4.2: Char PLS Treatment Unit Options
No full textWork Package 4 Char Leaching aims to demonstrate the feasibility for utilisation of the acidic leachates (biolixiviant) generated from coal wastes bioleaching (Work Package 3) as leaching agent for extraction of the base and high-value metals contained in the char originating from the pyrolysis of PCB’s (Work Package 2). After metals being leached from the char and accumulate in pregnant leach solution (PLS), the next task is to extract metal(s) of interest and recover it to obtain a high-purity product.
Different from mineral ores, char (or pyrolyzed PCBs) contains various metals and elements, oftentimes in high grades. Most of the time, the leaching of the char is non-selective, meaning that other than metals of interest, the un-desired ones should also be dissolved at high concentration. This is proven to be problematic for recovery stage, thus highlight the importance of extraction stage as intermediate between leaching and recovery.
The solvent extraction stage consists of two steps; extraction step to transfer metal ions from solution (aqueous) to extractant (organic), and stripping step to transfer metal ions back from organic to aqueous. Concentrated metal ions in the aqueous phase are then transferred to recovery stage to produce metal product with high purity. This report will subsequently present the result on investigation of solvent extraction to produce concentrated electrolyte solution, followed by the result on recovery stage by electrowinning to produce metal product.Co-processing of coal mine and electronic wastes: Novel resources for a sustainable future (CEReS
Special Crater Types on Vesta and Ceres as Revealed by Dawn
No full textThe exploration of two small planetary bodies by the Dawn mission revealed multifaced surfaces showing a diverse geology and surface features. Impact crater are the most distinctive features on these planetary bodies. The surfaces of asteroid Vesta and the dwarf planet Ceres reveal craters with an individual appearance as caused by different formation processes. Special topographic and subsurface conditions on both bodies have led to the development of special crater types. This chapter present the three most characteristic crater forms fund on both bodies. Asymmetric craters are found on both bodies, whereas ring-mold craters and floor-fractured craters are only visible on Ceres
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