Efficiency Improvement of Near‐Stoichiometric CuInSe2 Solar Cells for Application in Tandem Devices

State‐of‐the‐art Cu(In,Ga)Se₂ (CIGS) solar cells are grown with considerably substoichiometric Cu concentrations. The resulting defects, as well as potential improvements through increasing the Cu concentration, have been known in the field for many years. However, so far, cells with high Cu concentrations show decreased photovoltaic parameters. In this work, it is shown that RbF postdeposition treatment of CuInSe₂ solar cells allows for capturing the benefits from the improved absorber quality with increasing Cu content. A reduced defect density and an increased doping level for cells with high Cu concentrations close to stoichiometry are demonstrated. Implementing a high mobility front transparent conductive oxide (TCO), the improved absorbers with 1.00 eV bandgap yield a solar cell efficiency of 19.2%, and combined with a perovskite top cell a 4‐terminal tandem efficiency of 25.0% are demonstrated, surpassing the record efficiency of both subcell technologies.     

Accumulation and Transformation of Sulfonated Aromatic Compounds by Rhubarb Cells (Rheum palmatum)

Sulfonated aromatic compounds are released into the environment in large amounts: the main sources of these recalcitrant pollutants are anionic detergents, dyestuffs, and their byproducts, such as sulfonated anthraquinones. Different derivatives of anthraquinones occur naturally in several plant species such as rhubarb. Therefore, this plant could possess enzymes able to accept sulfonated anthraquinones as substrates. Previously, it has been shown that cultured cells isolated from Rheum palmatum are able to efficiently accumulate and transform different mono- and disulfonated anthraquinones. Because rhubarb is a hardy plant species, it may prove a promising candidate in developing new biological processes to decontaminate effluents containing recalcitrant xenobiotics. The ability of rhubarb cells to accumulate and transform other sulfonoaromatics was investigated in this study. Results obtained show that cultured rhubarb cells were able to efficiently accumulate 2-chloro-5-nitro-benzene sulfonate, both 2-hydroxy-4-sulfo- and 2-hydroxy-4-sulfo-6-nitro-naphthalene-diazonium, as well as 1,3-naphthalene disulfonates, containing either an amino or a nitro group in position 7. Rhubarb cells were also able to biotransform four of these compounds without releasing the metabolites formed.     

Habitat connectivity and dispersal ability drive the assembly mechanisms of macroinvertebrate communities in river networks

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Modeling of biological doses and mechanical effects on bone transduction

Shear stress, hormones like parathyroid and mineral elements like calcium mediate the amplitude of stimulus signal, which affects the rate of bone remodeling. The current study investigates the theoretical effects of different metabolic doses in stimulus signal level on bone. The model was built considering the osteocyte as the sensing center mediated by coupled mechanical shear stress and some biological factors. The proposed enhanced model was developed based on previously published works dealing with different aspects of bone transduction. It describes the effects of physiological doses variations of calcium, parathyroid hormone, nitric oxide and prostaglandin E2 on the stimulus level sensed by osteocytes in response to applied shear stress generated by interstitial fluid flow. We retained the metabolic factors (parathyroid hormone, nitric oxide and prostaglandin E2) as parameters of bone cell mechanosensitivity because stimulation/inhibition of induced pathways stimulates osteogenic response in vivo. We then tested the model response in terms of stimulus signal variation versus the biological factors doses to external mechanical stimuli. Despite the limitations of the model, it is consistent and has physiological bases. Biological inputs are histologically measurable. This makes the model amenable to experimental verification.     

Determination of human DNA replication origin position and efficiency reveals principles of initiation zone organisation

Replication of the human genome initiates within broad zones of ∼150 kb. The extent to which firing of individual DNA replication origins within initiation zones is spatially stochastic or localised at defined sites remains a matter of debate. A thorough characterisation of the dynamic activation of origins within initiation zones is hampered by the lack of a high-resolution map of both their position and efficiency. To address this shortcoming, we describe a modification of initiation site sequencing (ini-seq), based on density substitution. Newly replicated DNA is rendered ‘heavy-light’ (HL) by incorporation of BrdUTP while unreplicated DNA remains ‘light-light’ (LL). Replicated HL-DNA is separated from unreplicated LL-DNA by equilibrium density gradient centrifugation, then both fractions are subjected to massive parallel sequencing. This allows precise mapping of 23,905 replication origins simultaneously with an assignment of a replication initiation efficiency score to each. We show that origin firing within early initiation zones is not randomly distributed. Rather, origins are arranged hierarchically with a set of very highly efficient origins marking zone boundaries. We propose that these origins explain much of the early firing activity arising within initiation zones, helping to unify the concept of replication initiation zones with the identification of discrete replication origin sites.