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All-inorganic lead-free perovskites are emerging to replace the hybrid halide perovskite materials for light converting technology because of their expected superior thermal stability. Herein, we theoretically investigate the thermal stability, electronic and optical properties of double perovskites based on arsenic, antimony and bismuth, by using the density functional theory (DFT). We optimize the geometrical structures and predict the stable chemical potential regions for Cs2CuXCl6 (X = As, Sb, and Bi), to analyze the chemical conditions for obtaining single-phase structures. Furthermore, we calculate the bandgap energies, effective masses and light absorption coefficients, and elucidate that the photoelectric properties of these Cu-based double perovskites are suitable for photovoltaic applications. Our investigations provide a new routine for the design of lead-free halide perovskite solar absorbers. [ABSTRACT FROM AUTHOR]

Aldehyde groups were intentionally equipped on the cyanide-bridged [Fe2Co2] square molecules: {[(Tp*)Fe(CN)3Co(bpyCHO)2]2-[PF6]2}·4MeOH (1, Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate; bpyCHO = 4-formyl-4′-methyl-2,2′-bipyridine), thus providing chemical-active windows for post-modification towards desired functions. In this contribution, by taking advantage of efficient Schiff-base condensation between the aldehyde-substituted bipyridine derivative (bpyCHO) and alkyl diamines (H2N-(CH2)nNH2), two discrete [Fe2Co2] compounds { [ (Tp ∗) Fe (CN) 3 Co (bpy C = N (CH 2) n N = C bpy) ] 2 [ PF 6 ] 2 } ⋅ 6 DMF (2 , n = 5 ; 3 , n = 7) were prepared, where the cyanide-bridged [Fe2Co2] square cores were encapsulated by the flexible alkyl chains. Variable-temperature single-crystal X-ray diffraction and magnetic studies revealed complete thermo (T1/2 = 233 K (2) and 237 K (3)) and photo-induced electron transfer event accompanying spin transition between the diamagnetic [FeIILS2CoIIILS2] state and the paramagnetic [FeIIILS2CoIIHS2] state (LS, low spin; HS, high spin). In addition, the bidirectional switching between the two states was achieved with alternating laser irradiation at 808 and 532 nm at 10 K. [ABSTRACT FROM AUTHOR]

The substrates formed by the self-assembly method of metal nanoparticles are widely used in the molecular detection due to their high uniformity and good SERS properties. In this paper, we used the sliver nanorods as the building block for the first time to produce close-packed vertical arrays via evaporation-induced method. The results showed that the optimized substrates have good performance with excellent enhancement factor (4.47 × 105) and high reproducibility. By the time, we explore the relationship between the length of silver nanorods and the intensity of 4-mercaptobenzoic acid (4-MBA). The optimal SERS performance depended on longest silver nanorod length. In addition, the optimized vertical silver nanorod substrates exhibit 3 times than the optimized six-layer three-dimensional horizontal ones. Furthermore, the optimized substrate was able to directly detect malachite green (MG) down to 10−9 M. At the same time, the on-site detection of the thiram in the peel of apple is as low as 0.1 ng cm−2. The experimental results clearly show that our substrates have great potential for environmental monitoring, food safety and security application. [ABSTRACT FROM AUTHOR]

Histone deacetylases (HDACs) deacetylate lysine residues of histone and non-histone proteins and thereby regulate the cell-cycle, gene expression, and several other processes. We have analyzed the effects of HDAC1 on Runx2-mediated regulation of osteopontin (OPN) promoter activation and gene expression in mesenchymal progenitor C3h10t1/2 cells and show that co-expression of HDAC1 along with Runx2 results in down-regulation of Runx2-induced OPN mRNA expression during both the proliferation and differentiation stages of C3h10t1/2 cells. Luciferase assay results revealed that HDAC1 efficiently down-regulated Runx2-stimulated OPN promoter activity in a dose-dependent manner whereas TSA relieved the HDAC1-mediated repression and up-regulated the Runx2-induced OPN promoter activity and mRNA expression. In vivo HDAC1 co-localized and physically interacted with Runx2 and associated with the OPN promoter. Thus, HDAC1 not only plays a critical role in regulation of Runx2-stimulated expression of osteogenic genes, like OPN, but also regulate the proliferation and differentiation stages of mesenchymal progenitor cells, such as C3h10t1/2. [ABSTRACT FROM AUTHOR]

We present recent progresses on applying the theoretical models and computational tools in assessing the performance of organic solar cells, especially the bulk heterojunction solar cells. Both the continuum device model and the dynamic Monte Carlo model are developed to investigate the photocurrent-voltage characteristics based on the exciton and charge carrier dynamics. Insights into key factors influencing the organic photovoltaic performances have been gained from these studies. [ABSTRACT FROM AUTHOR]

Random packings of binary mixtures of spheres and spherocylinders with the same volume and the same diameter were simulated by a sphere assembly model and relaxation algorithm. Simulation results show that, independently of the component volume fraction, the mixture packing density increases and then decreases with the growth of the aspect ratio of spherocylinders, and the packing density reaches its maximum at the aspect ratio of 0.35. With the same volume particles, results show that the dependence of the mixture packing density on the volume fraction of spherocylinders is approximately linear. With the same diameter particles, the relationship between the mixture packing density and component volume fraction is also roughly linear for short spherocylinders, but when the aspect ratio of spherocylinders is greater than 1.6, the curves turn convex which means the packing of the mixture can be denser than either the sphere or spherocylinder packing alone. To validate the sphere assembly model and relaxation algorithm, binary mixtures of spheres and random packings of spherocylinders were also simulated. Simulation results show the packing densities of sphere mixtures agree with previous prediction models and the results of spherocylinders correspond with the simulation results in literature. [ABSTRACT FROM AUTHOR]

Theoretical work related to the self-assembly of organic materials was dealt with, and the various mechanisms leading to self-assembly, such as transition metal mediated self-assembly, constraint induced self-assembly, covalent bond based self-assembly and van der Waals interaction driven self-assembly, etc., were discussed. The formation of ordered structures could be attributed to the competition between short range attractive forces and long-range repulsion, which was arising from dipole interaction or may result from a different mechanism based on a purely repulsive isotropic short-range pair potential with two characteristic length scales. Such mechanism could be exploited in the study of self-assembly process. First principles SAPT(DFT) interaction energy calculations, combined with the Williams-Stone-Misquitta method, offer the ability to improve the molecular dynamics (MD) accuracy which could in turn be used in the prediction of crystal structures and self-assembly tendency. The combination of experimental and theoretical studies could open new breakthroughs over the design, synthesis, and characterization of self-assembled materials. [ABSTRACT FROM AUTHOR]

Using umbrella sampling technique with molecular dynamics simulation, we investigated the nanofluidic transport of water in carbon nanotube (CNT). The simulations showed that a positive charge modification to the carbon nanotube can slow down the water column growth process, while the negative charge modification to the carbon nanotube will, on the other hand, quicken the water column growth process. The free energy curves were obtained through the statistical process of water column growth under different charge distributions, and the results indicated that these free energy curves can be employed to explain the dynamical process of water column growth in the nanosized channels. [ABSTRACT FROM AUTHOR]