572 research outputs found

    Economic Development, Legality, and the Transplant Effect

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    We analyze the determinants of effective legal institutions (legality) using data from 49 countries. We show that the way the law was initially transplanted and received is a more important determinant than the supply of law from a particular legal family. Countries that have developed legal orders internally, adapted the transplanted law, and/or had a population that was already familiar with basic principles of the transplanted law have more effective legality than countries that received foreign law without any similar pre-dispositions. The transplanting process has a strong indirect effect on economic development via its impact on legality.http://deepblue.lib.umich.edu/bitstream/2027.42/39692/3/wp308.pd

    Legal Institutionalism: Capitalism and the Constitutive Role of Law

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    Social scientists have paid insufficient attention to the role of law in constituting the economic institutions of capitalism. Part of this neglect emanates from inadequate conceptions of the nature of law itself. Spontaneous conceptions of law and property rights that downplay the role of the state are criticized here, because they typically assume relatively small numbers of agents and underplay the complexity and uncertainty in developed capitalist systems. In developed capitalist economies, law is sustained through interaction between private agents, courts and the legislative apparatus. Law is also a key institution for overcoming contracting uncertainties. It is furthermore a part of the power structure of society, and a major means by which power is exercised. This argument is illustrated by considering institutions such as property and the firm. Complex systems of law have played a crucial role in capitalist development and are also vital for developing economies

    Advanced Luminescence Imaging of CIGS Solar Cells

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    The importance of CIGS based solar cells for terrestrial application increases steadily. A key issue for a high production yield are efficient inspection tools at the early stage of the production process. The present contribution focuses on imaging characterization of CIGS solar cells including photo and electroluminescence. PL imaging does not need electrical contacts and can be applied after the absorber deposition prior to the TCO deposition and the completion of the module. The effect of heat treatment on thermally evaporated In2S3 buffer layer with respect to the device performance is studied on the absorber amp;buffer stack by PL imaging. The correlation between PL intensity with achieved open circuit voltages of the completed devices has been established. It will be concluded that the quality of the buffer layer and the interface is well detectable at this early stage by PL imaging. The other issue addressed in this contribution is a characterization of graded gap absorbers by EL imaging. It will be demonstrated that luminescence imaging using optical bandpass filters can be used for the evaluation of the bandgap grading of CIGS absorbers fabricated by sequential processes. Furthermore, lateral inhomogeneities with respect to the In Ga intermixing can be detected already after the absorber deposition by the proposed PL imaging metho

    Time resolved investigation of Cu In,Ga Se2 growth and Ga gradient formation during fast selenization of metallic precursors

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    Ga segregation at the backside of Cu In,Ga Se2 solar cell absorbers is a commonly observed phenomenon for a large variety of sequential fabrication processes. Here, we investigate the correlation between Se incorporation, phase formation and Ga segregation during fast selenisation of Cu In Ga precursor films in elemental selenium vapour. Se incorporation and phase formation are analysed by real time synchrotron based X ray diffraction and fluorescence analysis. Correlations between phase formation and depth distributions are gained by interrupting the process at several points and by subsequent ex situ cross sectional electron microscopy and Raman spectroscopy. The presented results reveal that the main share of Se incorporation takes place within a few seconds during formation of In Se at the top part of the film, accompanied by outdiffusion of In out of a ternary Cu In Ga phase. Surprisingly, CuInSe2 starts to form at the surface on top of the In Se layer, leading to an intermediate double graded Cu depth distribution. The remaining Ga rich metal phase at the back is finally selenised by indiffusion of Se. On the basis of a proposed growth model, we discuss possible strategies and limitations for the avoidance of Ga segregation during fast selenisation of metallic precursors. Solar cells made from samples selenised with a total annealing time of 6.5 amp; 8201;min reached conversion efficiencies of up to 14.2 total area, without anti reflective coating . The evolution of the Cu In,Ga Se2 diffraction signals reveals that the minimum process time for high quality Cu In,Ga Se2 absorbers is limited by cation ordering rather than Se incorporatio

    A new approach for alkali incorporation in Cu2ZnSnS4 solar cells

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    The addition of alkali elements has become mandatory for boosting solar cell performance in chalcogenide thin films based on kesterites (Cu2ZnSnS4, CZTS). A novel doping process is presented here, that consists in the incorporation of sodium or lithium during the deposition of the CdS buffer layer, followed by a post-deposition annealing (PDA). As the doping route leads to more efficient devices in comparison with the undoped reference sample, the influence of PDA temperature was also investigated. Compositional profiling techniques, time-of-flight secondary ion mass spectrometry (TOF-SIMS) and glow discharge optical mission spectroscopy (GDOES), revealed a dependence of the alkaline distribution in kesterites with the PDA temperature. Although the doping process is effective in that it increases the alkaline concentration compared to the undoped sample, the compositional profiles indicate that a significant proportion of Li and Na remains ‘trapped’ within the CdS layer. In the 200 °C-300 °C range the alkali profiles registered the higher concentration inside the kesterite. Despite this, an additional alkali accumulation close to the molybdenum/fluorine doped tin oxide substrate was found for all the samples, which is frequently related to alkali segregation at interfaces. The addition of both, lithium and sodium, improves the photovoltaic response compared to the undoped reference device. This is mainly explained by a substantial improvement in the open-circuit potential (V oc) of the cells, with best devices achieving efficiencies of 4.5% and 3% for lithium and sodium, respectively. Scanning-electron microscopy images depicted a ‘bilayer structure’ with larger grains at the top and small grains at the bottom in all samples. Moreover, the calculated bandgap energies of the CZTS films account for changes in the crystallographic order-disorder of the kesterites, more related to the PDA treatment rather than alkali incorporation. Even if further optimization of the absorber synthesis and doping process will be required, this investigation allowed the evaluation of a novel strategy for alkali incorporation in kesterite based solar cells.Fil: Valdes, Matias Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Hernandez, A.. Catalonia Institute For Energy Research Irec; EspañaFil: Sánchez, Y.. Catalonia Institute For Energy Research Irec; EspañaFil: Fonoll, R.. Catalonia Institute For Energy Research Irec; EspañaFil: Placidi, M.. Universidad Politécnica de Catalunya; España. Catalonia Institute For Energy Research Irec; EspañaFil: Izquierdo, V.. Catalonia Institute For Energy Research Irec; EspañaFil: Cabas Vidani, A.. Swiss Federal Laboratories for Materials Science and Technology; SuizaFil: Valentini, M.. Enea Centro Ricerche Casaccia; ItaliaFil: Mittiga, A.. Enea Centro Ricerche Casaccia; ItaliaFil: Pistor, P.. Universidad Pablo de Olavide; EspañaFil: Malerba, C.. Enea Centro Ricerche Casaccia; ItaliaFil: Saucedo, E.. Universidad Politécnica de Catalunya; Españ

    New Grain Formation Mechanisms during Powder Bed Fusion

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    Tailoring the mechanical properties of parts by influencing the solidification conditions is a key topic of powder bed fusion. Depending on the application, single crystalline, columnar, or equiaxed microstructures are desirable. To produce single crystals or equiaxed microstructures, the control of nucleation is of outstanding importance. Either it should be avoided or provoked. There are also applications, such as turbine blades, where both microstructures at different locations are required. Here, we investigate nucleation at the melt-pool border during the remelting of CMSX-4® samples built using powder bed fusion. We studied the difference between remelting as-built and homogenized microstructures. We identified two new mechanisms that led to grain formation at the beginning of solidification. Both mechanisms involved a change in the solidification microstructure from the former remelted and newly forming material. For the as-built samples, a discrepancy between the former and new dendrite arm spacing led to increased interdentritic undercooling at the beginning of solidification. For the heat-treated samples, the collapse of a planar front led to new grains. To identify these mechanisms, we conducted experimental and numerical investigations. The identification of such mechanisms during powder bed fusion is a fundamental prerequisite to controlling the solidification conditions to produce single crystalline and equiaxed microstructures

    AMBRA1 is able to induce mitophagy via LC3 binding, regardless of PARKIN and p62/SQSTM1

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    Damaged mitochondria are eliminated by mitophagy, a selective form of autophagy whose dysfunction associates with neurodegenerative diseases. PINK1, PARKIN and p62/SQTMS1 have been shown to regulate mitophagy, leaving hitherto ill-defined the contribution by key players in 'general' autophagy. In basal conditions, a pool of AMBRA1 - an upstream autophagy regulator and a PARKIN interactor - is present at the mitochondria, where its pro-autophagic activity is inhibited by Bcl-2. Here we show that, upon mitophagy induction, AMBRA1 binds the autophagosome adapter LC3 through a LIR (LC3 interacting region) motif, this interaction being crucial for regulating both canonical PARKIN-dependent and -independent mitochondrial clearance. Moreover, forcing AMBRA1 localization to the outer mitochondrial membrane unleashes a massive PARKIN- and p62-independent but LC3-dependent mitophagy. These results highlight a novel role for AMBRA1 as a powerful mitophagy regulator, through both canonical or noncanonical pathways

    New Grain Formation by Constitutional Undercooling Due to Remelting of Segregated Microstructures during Powder Bed Fusion

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    A microstructure has significant influence on the mechanical properties of parts. For isotropic properties, the formation of equiaxed microstructures by the nucleation of new grains during solidification is necessary. For conventional solidification processes, nucleation is well-understood. Regarding powder bed fusion, the repeated remelting of previous layers can cause nucleation under some conditions that are not explainable with classical theories. Here, we investigate this nucleation mechanism with an unprecedented level of detail. In the first step, we built samples with single crystalline microstructures from Ni-base superalloy IN718 by selective electron beam melting. In the second step, single lines with different parameters were molten on top of these samples. We observed a huge number of new grains by nucleation at the melt-pool border of these single lines. However, new grains can only prevail if the alignment of their crystallographic orientation with respect to the local temperature gradient is superior to that of the base material. The current hypothesis is that nucleation at the melt-pool border happens due to remelting microsegregations from former solidification processes leading to constitutional undercooling directly at the onset of solidification. This study offers the opportunity to understand and exploit this mechanism for different manufacturing processes
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