The recently discovered hybrid organic-inorganic perovskites have been suggested for high-performance optoelectronic applications. Owing to the mechanical flexibility of these compounds, they demonstrate structural fluctuation at finite temperatures that have been widely discussed with respect to their optical properties. However, the effect of temperature-induced structural fluctuation is not clear until now, with respect to the equally important charge transport properties. In the present study, through ab initio molecular dynamics simulations of cubic-phase CH NH PbI at different temperatures, the temperature-dependent electronic structure and charge carrier transport properties are examined. Compared with the significant structural fluctuation of organic cations, the structural change of the inorganic framework is minor. In addition, because the band edge states at R point are mainly influenced by the anti-bonding character of the Pb-I bond, CH NH PbI demonstrates relatively small deformation potentials as well as low temperature dependence of band gaps (ΔE ≈ 50 meV from 330 K to 400 K) and electron-phonon coupling strengths, despite the large structural fluctuation of organic cations. Furthermore, the effective mass of the valence band increases with the increase of temperature. The predicted mobilities of CH NH PbI can reach above 75 cm V s near room temperature, exhibiting an appropriate optoelectronic potential, while the temperature dependence is steeper than T of the traditional semiconductors because of the enhanced effective masses.
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PLoS One
January 2025
Organic Plant Production and Agroecosystems Research in the Tropics and Subtropics, Universität Kassel, Kassel, Germany.
Sand, shaping both natural waterways and urban infrastructure, has recently seen a major surge in extraction, particularly in rapidly urbanizing regions like West Africa. To assess the organization, quantification, and socio-ecological implications of sand mining around Mali's capital Bamako, we employed a mixed methods approach including structured and unstructured interviews, truck counts, turbidity analyses, and river depth measurements. Our study identified five artisanal systems for mining sand and gravel from the Niger River, using tied-up pirogues, single pirogues, carts, tractors, and trucks.
View Article and Find Full Text PDFContact (Thousand Oaks)
January 2025
Department of Biomedicine, Centro de Investigaciones Biológicas Margarita Salas, CSIC, 28040 Madrid, Spain.
Microglia, the resident immune cells of the central nervous system (CNS), play a crucial role in maintaining tissue homeostasis by monitoring and responding to environmental changes through processes such as phagocytosis, cytokine production or synapse remodeling. Their dynamic nature and diverse functions are supported by the regulation of multiple metabolic pathways, enabling microglia to efficiently adapt to fluctuating signals. A key aspect of this regulation occurs at mitochondria-associated ER membranes (MAM), specialized contact sites between the ER and mitochondria.
View Article and Find Full Text PDFR Soc Open Sci
January 2025
Department of Chemistry, Jagannath University, Dhaka 1100, Bangladesh.
In this study, three pyridine- and four thiophene-containing chalcone derivatives were synthesized via Claisen-Schmidt condensation reaction, where five derivatives were new. Different spectral analyses (IR, H NMR, HRMS) clarified the structures and these proposed compounds were screened for antimicrobial activity by the agar disc diffusion technique. Compound was conspicuously active against most of the bacterial and fungal strains.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States.
The polycrystalline nature of perovskites, stemming from their facile solution-based fabrication, leads to a high density of grain boundaries (GBs) and point defects. However, the impact of GBs on perovskite performance remains uncertain, with contradictory statements found in the literature. We developed a machine learning force field, sampled GB structures on a nanosecond time scale, and performed nonadiabatic (NA) molecular dynamics simulations of charge carrier trapping and recombination in stoichiometric and doped GBs.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
February 2025
Department of Biosphere Sciences and Engineering, Carnegie Institution for Science, Stanford, CA 94305.
Microbial mats are stratified communities often dominated by unicellular and filamentous phototrophs within an exopolymer matrix. It is challenging to quantify the dynamic responses of community members in situ as they experience steep gradients and rapid fluctuations of light. To address this, we developed a binary consortium using two representative isolates from hot spring mats: the unicellular oxygenic phototrophic cyanobacterium OS-B' (Syn OS-B') and the filamentous anoxygenic phototroph MS-CIW-1 (Chfl MS-1).
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