Solar silicon from directional solidification of MG silicon produced via the silicon carbide route

A process of metallurgical grade (MG) silicon production is presented which appears particularly suitable for photovoltaic (PV) applications. The MG silicon is prepared in a 240 KVA, three electrode submerged arc furnace, starting from high grade quartz and high purity silicon carbide. The silicon smelted from the arc furnace was shown to be sufficiently pure to be directionally solidified to 10 to 15 kg. After grinding and acid leaching, had a material yield larger than 90%. With a MG silicon feedstock containing 3 ppmw B, 290 ppmw Fe, 190 ppmw Ti, and 170 ppmw Al, blended with 50% of off grade electronic grade (EG) silicon to reconduct the boron content to a concentration acceptable for solar cell fabrication, the 99% of deep level impurities were concentrated in the last 5% of the ingot. Quite remarkably this material has OCV values higher tham 540 mV and no appreciable shorts due to SiC particles

Zur Berechnung von Holzschalen in Brettrippenbauweise mit elastischem Verbundquerschnitt

The design of timber rip shells confronts the engineer with major uncertainties during the planning process. The consideration of the elastic compound cross section during structural analysis of curved members by means of conventional calculation methods is possible only in a restricted manner. The shear-analogy provides a seemingly useful method for calculating these structures. However it is only an approximation, particularly with regard to cross sections with high flexibility in terms of shear stress. This thesis treats the limitations of applying of the shearanalogy with regard to the calculation of straight and curved members with elastic compound cross section. The bending of timber lamellas generates initial bending stress. Due to the rheological behaviour of wood and the associated process of plastification within the microstructure of wood, the stress becomes partially reduced as a function of time (stress relaxation). Prior work provides contradictory information about the duration and intensity of this reduction. To shed light on these uncertainties, appropriate experiments have been conducted. To join timber lamellas to a multi-layered cross section, mechanical fasteners like screws, nails and bolts are used. The knowledge of the physical properties, like rigidity and resistance, are of significant importance for the verification of the ultimate limit states. Tests conducted in the past in order to evaluate theoretical models and to determine empirical values refer generally to connections, which differ clearly from the multi-layered connection treated here concerning the deformation and failure mechanisms. Experiments carried out provide estimation in how far the existing values can be applied to structural analysis of the present case. The theoretical model according to Johansen was adapted in an appropriate manner. The aim of the work presented here is to contribute to the clarification of several problems related to the design of spatial timber structures with elastic compound cross section. The results provide further confidence to engineers for planning and realising these challenging lightweight structures

Board of Directors' characteristics and environmental SDGs adoption: an international study

Drivers of environmentally conscious firm behaviour have gained increasing attention over past decades. The Board of Directors holds a central role in corporate decision-making, and previous empirical evidence suggests that its characteristics could influence corporate environmental performance. This paper contributes to the literature with the first evidence of the influence certain board characteristics have on whether a firm ulti-mately supports one or more environmental SDGs. Our focus is on board size, gender diversity, board independence and CEO duality. Logistic and fractional regressions on 4417 globally listed firms highlight that board size, the share of female directors, and the share of independent directors are significant drivers of support for environmental SDGs. The results and insights revealed in this study should be helpful to policymakers, investors and corporations in evaluating the effectiveness of corporate governance characteristics and fostering corporate contributions to the 2030 Agenda

The PNPLA3 I148M variant and chronic liver disease : When a genetic mutation meets nutrients

Abstract The isoleucine to methionine substitution at position 148 in the patatin-like phospholipase domain containing 3 protein (PNPLA3; I148M variant, rs738409) is associated with liver fat accumulation and an increased risk of chronic liver disease ranging from hepatitis to hepatocellular carcinoma. This review discusses the interaction between the PNPLA3 I148M variant and obesity/intake of specific nutrients in determining the susceptibility to liver disease. We present the results of several studies showing that obesity or alcohol abuse enhances the effect of the PNPLA3 I148M variant on the liver. We also show that specific nutrients interact with the PNPLA3 I148M variant in modulating liver disease susceptibility

Geodesic Lines on Free-Form Surfaces - Optimized Grids for Timber Rib Shells

In addition to glue-laminated timber, screw-laminated timber has increasingly been applied to rib shells. The ribs are made from laminated timber boards, which are joined together with the aid of pin-like fasteners such as screws or nails. The current research is meant to optimize these grids on free-form surfaces with regard to the bending stress due to initial curvature of the boards. This can be done by arranging the ribs according to geodesic lines which allows the application of straight boards, subjected only to bending about their week axis and to torsion. The determination of such geodesic grids on free-form surfaces, currently enjoying great popularity in contemporary architecture, is quite complex. In order to satisfy this demand and to improve automation of the production process, the software GEOS has been developed in close collaboration with the Laboratory of Timber Construction (EPFL/IBOIS) and the chair of Geometry (EPFL/GEOM). This software calculates grids of geodesic lines on free-form surfaces and provides all geometrical data necessary for computer-controlled sawing. Free-form surfaces are treated as Bézier surfaces. In order to proved the reliability of the assumptions the program is based upon, a timber rib shell prototype (length/width/height: 8000 mm x 3000 mm x 2060 mm) was build. Thin timber laths (12/60 mm) were used. All laths were sawn and predrilled by means of computer-controlled sawing. The prototype could thus be built in relatively short time. In general, it can be stated that even after assembly of the fourth layer the predrilled holes at the intersections fitted precisely about 85% of the time. This confirms the reliability of the calculation and shows that the demanded precision is kept even for significant curvatures. For a better understanding of the load-bearing behavior of the structure load tests were carried out. The comparison of the measured deformations with the calculated deformations enabled us to evaluate the calculation model, based on a framed load-bearing system. For small charges, good accordance between calculation and reality could be noticed. The software GEOS provides an important tool for the design and the realization of timber rib shells. It contributes to clarifying current uncertainties in the design planning process and will highly improve the confidence of engineers and architects in conceiving and realizing this type of challenging lightweight spatial structures

Konstruktion und Berechnung von biegebeanspruchten Rippenschalen und anderen Flächentragwerken in Brettstapelbauweise

Grenzen der Anwendung des Schubanalogieverfahrens auf mehrschichtige gerade und gekrümmte Strukturen werden aufgezeigt und diskutiert. Durchführung von Versuchen zur Untersuchung der Relaxation der Anfangsbiegespannungen infolge konstruktionsbedingter Krümmung. Die verbleibenden Spannungsanteile müssen bei den Nachweisen im Grenzzustand der Tragfähigkeit berücksichtigt werden. Zur Untersuchung der Besonderheiten des Einsatzes von stiftförmigen Verbindungsmitteln für mehrschichtige Verbundträger aus dünnen Lamellen wurden Druckscherversuche durchgeführt. Es zeigt sich, dass die Rechenwerte der Steifigkeit und der Tragfähigkeit nach der Norm SIA 265 nur sehr eingeschränkt anwendbar sind. Die Traglastmodelle nach Johansen wurden modifiziert und entsprechende Ueberlegungen für die Steifigkeit angestellt

Board of Directors' characteristics and environmental SDGs adoption: an international study

Drivers of environmentally conscious firm behaviour have gained increasing attention over past decades. The Board of Directors holds a central role in corporate decision-making, and previous empirical evidence suggests that its characteristics could influence corporate environmental performance. This paper contributes to the literature with the first evidence of the influence certain board characteristics have on whether a firm ultimately supports one or more environmental SDGs. Our focus is on board size, gender diversity, board independence and CEO duality. Logistic and fractional regressions on 4417 globally listed firms highlight that board size, the share of female directors, and the share of independent directors are significant drivers of support for environmental SDGs. The results and insights revealed in this study should be helpful to policymakers, investors and corporations in evaluating the effectiveness of corporate governance characteristics and fostering corporate contributions to the 2030 Agenda

The faah gene is the first direct target of estrogen in the testis: role of histone demethylase LSD1

Estrogen (E(2)) regulates spermatogenesis, yet its direct target genes have not been identified in the testis. Here, we cloned the proximal 5' flanking region of the mouse fatty acid amide hydrolase (faah) gene upstream of the luciferase reporter gene, and demonstrated its promoter activity and E(2) inducibility in primary mouse Sertoli cells. Specific mutations in the E(2) response elements (ERE) of the faah gene showed that two proximal ERE sequences (ERE2/3) are essential for E(2)-induced transcription, and chromatin immunoprecipitation experiments showed that E(2) induced estrogen receptor β binding at ERE2/3 sites in the faah promoter in vivo. Moreover, the histone demethylase LSD1 was found to be associated with ERE2/3 sites and to play a role in mediating E(2) induction of FAAH expression. E(2) induced epigenetic modifications at the faah proximal promoter compatible with transcriptional activation by remarkably decreasing methylation of both DNA at CpG site and histone H3 at lysine 9. Finally, FAAH silencing abolished E(2) protection against apoptosis induced by the FAAH substrate anandamide. Taken together, our results identify FAAH as the first direct target of E(2)