Defects in Halide Perovskites: Does It Help to Switch from 3D to 2D?

Ruddlesden-Popper hybrid iodide 2D perovskites are put forward as stable alternatives to their 3D counterparts. Using first-principles calculations, we demonstrate that equilibrium concentrations of point defects in the 2D perovskites PEA$_2$PbI$_4$, BA$_2$PbI$_4$, and PEA$_2$SnI$_4$ (PEA: phenethyl ammonium, BA: butylammonium), are much lower than in comparable 3D perovskites. Bonding disruptions by defects are more detrimental in 2D than in 3D networks, making defect formation energetically more costly. The stability of 2D Sn iodide perovskites can be further enhanced by alloying with Pb. Should, however, point defects emerge in sizable concentrations as a result of nonequilibrium growth conditions, for instance, then those defects hamper the optoelectronic performance of the 2D perovskites, as they introduce deep traps. We suggest that trap levels are responsible for the broad sub-bandgap emission in 2D perovskites observed in experiments

Blockage of bone marrow kinase in chromosome X enhances ABC294640-induced growth inhibition and apoptosis of colorectal cancer cells

Purpose: To investigate the role of bone marrow kinase in chromosome X (BMX) in colorectal cancer (CRC) cell resistance to ABC294640 treatment.Methods: HCT-116R, LS174T and WiDr cells were transfected with either BMX-specific siRNA or scrambled siRNA, and then BMX mRNA and protein expressions were detected by quantitative polymerase chain reaction (qPCR) and western blotting, respectively. The cells were treated with ABC294640 and cell viability evaluated using cell counting and colony formation assays. Apoptosis wasdetermined by detecting caspase 3/7 activity. To evaluate tumor growth of  HCT-116R cells, a xenograft model was utilized to measure tumor size.Results: Pharmacological inhibition of sphingosine kinase type 2 (SK2) with ABC294640 significantly decreased cell viability (p < 0.001) when compared with control group. SK2 inhibition also remarkably induced apoptosis in HCT-116 CRC cells in a dose-dependent manner (p < 0.01 and p < 0.001). However, no significant effects were observed in HCT-116R, LS174T, or WiDr cells following ABC294640 treatment. BMX mRNA and protein expression increased in ABC294640-resistant cell lines. In addition, silencing BMX expression with siRNA potentiated  ABC294640-induced inhibition of tumor growth in CRC cells in vitro and in vivo.Conclusion: ABC294640-induced BMX upregulation impedes the antitumor effect of ABC294640 in CRC cells. Therefore, these results may provide a novel therapeutic strategy for CRC using a combination of ABC294640 treatment and BMX blockade.Keywords: ABC294640, Apoptosis, Bone marrow kinase in chromosome X, Cell viability, Colorectal cance

Defects in Halide Perovskites:Does It Help to Switch from 3D to 2D?

Two-dimensional (2D) organic-inorganic hybrid iodide perovskites have been put forward in recent years as stable alternatives to their three-dimensional (3D) counterparts. Using first-principles calculations, we demonstrate that equilibrium concentrations of point defects in the 2D perovskites PEA2PbI4, BA2PbI4, and PEA2SnI4 (PEA, phenethylammonium; BA, butylammonium) are much lower than in comparable 3D perovskites. Bonding disruptions by defects are more destructive in 2D than in 3D networks, making defect formation energetically more costly. The stability of 2D Sn iodide perovskites can be further enhanced by alloying with Pb. Should, however, point defects emerge in sizable concentrations as a result of nonequilibrium growth conditions, for instance, then those defects likely hamper the optoelectronic performance of the 2D perovskites, as they introduce deep traps. We suggest that trap levels are responsible for the broad sub-bandgap emission in 2D perovskites observed in experiments.</p

Compound Defects in Halide Perovskites: A First-Principles Study of CsPbI3_3

Lattice defects affect the long-term stability of halide perovskite solar cells. Whereas simple point defects, i.e., atomic interstitials and vacancies, have been studied in great detail, here we focus on compound defects that are more likely to form under crystal growth conditions, such as compound vacancies or interstitials, and antisites. We identify the most prominent defects in the archetype inorganic perovskite CsPbI$_3$, through first-principles density functional theory (DFT) calculations. We find that under equilibrium conditions at room temperature, the antisite of Pb substituting Cs forms in a concentration comparable to those of the most prominent point defects, whereas the other compound defects are negligible. However, under nonequilibrium thermal and operating conditions, other complexes also become as important as the point defects. Those are the Cs substituting Pb antisite, and, to a lesser extent, the compound vacancies of PbI$_2$ or CsPbI$_3$ units, and the I substituting Cs antisite. These compound defects only lead to shallow or inactive charge carrier traps, which testifies to the electronic stability of the halide perovskites. Under operating conditions with a quasi Fermi level very close to the valence band, deeper traps can develop

Validation of Konsung Compass 2000 Dry Biochemical Analyzer

Dry biochemical analyzers have been increasingly popular in many tests by primary hospitals, field hospitals and other areas subject to economic and medical underdevelopment as well as poor transportation. With the increasing demand for POCT in primary medical care around the world, upgrading of dry biochemical analyzers has been a hot topic in technical research. Against such context, Konsung Compass2000 dry biochemical analyzer, a POCT system with high precision and accuracy, is developed. Furthermore, the upgraded dry biochemical analyzers can, in a more convenient and accurate way, monitor glucose, lipid and other indices affecting the course of chronic diseases