A new approach for alkali incorporation in Cu2ZnSnS4 solar cells

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

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

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

Microtubules as Platforms for Assaying Actin Polymerization In Vivo

The actin cytoskeleton is continuously remodeled through cycles of actin filament assembly and disassembly. Filaments are born through nucleation and shaped into supramolecular structures with various essential functions. These range from contractile and protrusive assemblies in muscle and non-muscle cells to actin filament comets propelling vesicles or pathogens through the cytosol. Although nucleation has been extensively studied using purified proteins in vitro, dissection of the process in cells is complicated by the abundance and molecular complexity of actin filament arrays. We here describe the ectopic nucleation of actin filaments on the surface of microtubules, free of endogenous actin and interfering membrane or lipid. All major mechanisms of actin filament nucleation were recapitulated, including filament assembly induced by Arp2/3 complex, formin and Spir. This novel approach allows systematic dissection of actin nucleation in the cytosol of live cells, its genetic re-engineering as well as screening for new modifiers of the process

Nephronophthisis

Nephronophthisis (NPH) is an autosomal recessive disease characterized by a chronic tubulointerstitial nephritis that progress to terminal renal failure during the second decade (juvenile form) or before the age of 5 years (infantile form). In the juvenile form, a urine concentration defect starts during the first decade, and a progressive deterioration of renal function is observed in the following years. Kidney size may be normal, but loss of corticomedullary differentiation is often observed, and cysts occur usually after patients have progressed to end-stage renal failure. Histologic lesions are characterized by tubular basement membrane anomalies, tubular atrophy, and interstitial fibrosis. The infantile form is characterized by cortical microcysts and progression to end-stage renal failure before 5 years of age. Some children present with extrarenal symptoms: retinitis pigmentosa (Senior-Løken syndrome), mental retardation, cerebellar ataxia, bone anomalies, or liver fibrosis. Positional cloning and candidate gene approaches led to the identification of eight causative genes (NPHP1, 3, 4, 5, 6, 7, 8, and 9) responsible for the juvenile NPH and one gene NPHP2 for the infantile form. NPH and associated disorders are considered as ciliopathies, as all NPHP gene products are expressed in the primary cilia, similarly to the polycystic kidney disease (PKD) proteins

Nothing New in the (North) East? Interpreting the Rhetoric and Reality of Japanese Corporate Governance

Japan finally seems to be pulling itself out of its lost decade (and a half) of economic stagnation. Some grudgingly or triumphantly attribute this to micro-economic reforms, freeing up arthritic markets, although there is also evidence that macro-economic policy failures have been a major cause of poor performance since the 1990s. Many point to overlapping transformations in corporate governance, broadly defined to cover relationships among managers and employees as well as between firms and outside shareholders, creditors, and other stakeholders. These relationships are in flux, with moves arguably favouring shareholders and more market-driven control mechanisms. It has certainly been a found decade for law reform in Japan, particularly in corporate law, with a plethora of legislative amendments commencing around 1993 and culminating in the enactment of a consolidated Company Law in 2005. This modernisation project, particularly since 2001, is reportedly aimed at (i) securing better corporate governance, (ii) bringing the law into line with a highly-developed information society, (iii) liberalising fundraising measures, (iv) bringing corporate law into line with the internationalization of corporate activity, and (v) modernizing terms and consolidating corporate law. Because the suite of revisions has moved away from strict mandatory rules set out originally in Japan\u27s Commercial Code of 1899, modeled primarily on German law, another growing perception is that Japanese corporate law and practice is or will soon be converging significantly on US models. However, assessments remain divided as to whether these moves in corporate governance and capitalism more generally in Japan amount to a new paradigm or regime shift . Focusing primarily on quite influential commentary in English, Part I of this paper outlines two pairs of views. It concludes that the most plausible assessment is of significant but gradual transformation towards a more market-driven approach, evident also in other advanced political economies. Drawing more generally from these often virulently divided views, Part II sets out five ways forward through the proliferating literature and source material on corporate governance in Japan. Particular care must be taken in: (i) selecting the temporal timeframe, (ii) selecting countries to compare, (iii) balancing black-letter law and broader socio-economic context, (iv) reflecting on and disclosing normative preferences, and (v) giving weight to processes as well as outcomes, when assessing change in Japan - and any other country\u27s governance system. Part III ends with a call for further research particularly on law- and policy-producing processes, rather than mainly outcomes. It also outlines the usefulness of this analytical framework for analysing the broader field of Corporate Social Responsibility, now emerging as the next major area of debate and transformation in Japan - as elsewhere