Spectroscopic Analysis for the Identification of Loss Mechanisms in Back-Contact Perovskite Solar Cells

Back-contact perovskite solar cells offer a significant potential to reach high efficiency due to reduced parasitic absorption from the top surface. However, the currently reported efficiencies are considerably lower (&lt;10%) than planar perovskite solar cells (&gt;20%). Herein, back-contact perovskite solar cells are fabricated to study loss mechanisms that cause low device efficiency. This work spatially resolves the short-circuit current, open-circuit voltage, photoluminescence quantum yield, carrier lifetime, and external quantum efficiency of the devices. The results indicate that the front surface recombination, increased nonradiative recombination at hole contact layer/perovskite interface, and the extraction barriers are three main mechanisms limiting devices from achieving high efficiencies.</p

Controlling Optically Driven Atomic Migration Using Crystal-Facet Control in Plasmonic Nanocavities.

Plasmonic nanoconstructs are widely exploited to confine light for applications ranging from quantum emitters to medical imaging and biosensing. However, accessing extreme near-field confinement using the surfaces of metallic nanoparticles often induces permanent structural changes from light, even at low intensities. Here, we report a robust and simple technique to exploit crystal facets and their atomic boundaries to prevent the hopping of atoms along and between facet planes. Avoiding X-ray or electron microscopy techniques that perturb these atomic restructurings, we use elastic and inelastic light scattering to resolve the influence of crystal habit. A clear increase in stability is found for {100} facets with steep inter-facet angles, compared to multiple atomic steps and shallow facet curvature on spherical nanoparticles. Avoiding atomic hopping allows Raman scattering on molecules with low Raman cross-section while circumventing effects of charging and adatom binding, even over long measurement times. These nanoconstructs allow the optical probing of dynamic reconstruction in nanoscale surface science, photocatalysis, and molecular electronics.ER

Election staff training: Tracing global patterns of institutionalisation

The safe delivery of elections is a pivotal international issue in an era of widespread concerns about global democratic backsliding. Despite this, there remains little research on the training provided to electoral officials – those responsible for delivering elections and democracy on the front line. This article introduces the concept of electoral training institutionalisation, which refers to the extent to which training is embedded into electoral processes by electoral management bodies. It then presents original data from a survey of electoral management bodies to give an overview of the global provision of training. An original index of training institutionalisation is developed from the dataset. These data are analysed to identify the patterns of training. The results suggest that training institutionalisation tends to be associated with the overall quality of democracy and economic development. Deepening the embeddedness of electoral training is recommended as a step towards the strengthening of electoral democracy

Ten-year assessment of the 100 priority questions for global biodiversity conservation

In 2008, a group of conservation scientists compiled a list of 100 priority questions for the conservation of the world's biodiversity ?Sutherland et al. (2009) Conservation Biology, 23, 557?567?. However, now almost a decade later, no one has yet published a study gauging how much progress has been made in addressing these 100 high?priority questions in the peer?reviewed literature. Here we take a first step toward re?examining the 100 questions and identify key knowledge gaps that still remain. Through a combination of a questionnaire and a literature review, we evaluated each of the 100 questions on the basis of two criteria: relevance and effort. We defined highly?relevant questions as those which ? if answered ? would have the greatest impact on global biodiversity conservation, while effort was quantified based on the number of review publications addressing a particular question, which we used as a proxy for research effort. Using this approach we identified a set of questions that, despite being perceived as highly relevant, have been the focus of relatively few review publications over the past ten years. These questions covered a broad range of topics but predominantly tackled three major themes: the conservation and management of freshwater ecosystems, the role of societal structures in shaping interactions between people and the environment, and the impacts of conservation interventions. We see these questions as important knowledge gaps that have so far received insufficient attention and may need to be prioritised in future research

How many bird and mammal extinctions has recent conservation action prevented?

Aichi Target 12 of the Convention on Biological Diversity (CBD) aims to ‘prevent extinctions of known threatened species’. To measure its success, we used a Delphi expert elicitation method to estimate the number of bird and mammal species whose extinctions were prevented by conservation action in 1993 - 2020 (the lifetime of the CBD) and 2010 - 2020 (the timing of Aichi Target 12). We found that conservation prevented 21–32 bird and 7–16 mammal extinctions since 1993, and 9–18 bird and 2–7 mammal extinctions since 2010. Many remain highly threatened, and may still become extinct in the near future. Nonetheless, given that ten bird and five mammal species did go extinct (or are strongly suspected to) since 1993, extinction rates would have been 2.9–4.2 times greater without conservation action. While policy commitments have fostered significant conservation achievements, future biodiversity action needs to be scaled up to avert additional extinctions

Gene Expression Profiling in the Type 1 Diabetes Rat Diaphragm

BACKGROUND:Respiratory muscle contractile performance is impaired by diabetes, mechanisms of which included altered carbohydrate and lipid metabolism, oxidative stress and changes in membrane electrophysiology. The present study examined to what extent these cellular perturbations involve changes in gene expression. METHODOLOGY/PRINCIPAL FINDINGS:Diaphragm muscle from streptozotocin-diabetic rats was analyzed with Affymetrix gene expression arrays. Diaphragm from diabetic rats had 105 genes with at least +/-2-fold significantly changed expression (55 increased, 50 decreased), and these were assigned to gene ontology groups based on over-representation analysis using DAVID software. There was increased expression of genes involved in palmitoyl-CoA hydrolase activity (a component of lipid metabolism) (P = 0.037, n = 2 genes, fold change 4.2 to 27.5) and reduced expression of genes related to carbohydrate metabolism (P = 0.000061, n = 8 genes, fold change -2.0 to -8.5). Other gene ontology groups among upregulated genes were protein ubiquitination (P = 0.0053, n = 4, fold change 2.2 to 3.4), oxidoreductase activity (P = 0.024, n = 8, fold change 2.1 to 6.0), and morphogenesis (P = 0.012, n = 10, fold change 2.1 to 4.3). Other downregulated gene groups were extracellular region (including extracellular matrix and collagen) (P = 0.00032, n = 13, fold change -2.2 to -3.7) and organogenesis (P = 0.032, n = 7, fold change -2.1 to -3.7). Real-time PCR confirmed the directionality of changes in gene expression for 30 of 31 genes tested. CONCLUSIONS/SIGNIFICANCE:These data indicate that in diaphragm muscle type 1 diabetes increases expression of genes involved in lipid energetics, oxidative stress and protein ubiquitination, decreases expression of genes involved in carbohydrate metabolism, and has little effect on expression of ion channel genes. Reciprocal changes in expression of genes involved in carbohydrate and lipid metabolism may change the availability of energetic substrates and thereby directly modulate fatigue resistance, an important issue for a muscle like the diaphragm which needs to contract without rest for the entire lifetime of the organism