Investigation of the Stability of Methylammonium Lead Iodide (MAPbI3) Film Doped with Lead Cesium Triiodide (CsPbI3) Quantum Dots under an Oxygen Plasma Atmosphere

In this study, we describe composited perovskite films based on the doping of lead cesium triiodide (CsPbI₃) quantum dots (QDs) into methylammonium lead iodide (MAPbI₃). CsPbI₃ QDs and MAPbI₃ were prepared by ligand-assisted re-precipitation and solution mixing, respectively. These films were optimized by oxygen plasma treatment, and the effect of powers from 0 to 80 W on the structural properties of the composited perovskite films is discussed. The experimental results showed that the light-harvesting ability of the films was enhanced at 20 W. The formation of the metastable state (lead(II) oxide and lead tetroxide) was demonstrated by peak differentiation-imitating. A low power enhanced the quality of the films due to the removal of organic impurities, whereas a high power caused surface damage in the films owing to the severe degradation of MAPbI₃.     

Synthesis and characterization of Cu(I) and Cu(II) complexes containing ketiminate ligands

A series of Cu(I) and Cu(II) complexes containing substituted ketiminate ligands was synthesized. Reaction of CuCl₂ with 2 equiv. of Li[OC(Me)CHC(Me)N(Ar)] in toluene generated dark green solid of Cu[OC(Me)CHC(Me)N(Ar)]₂ (1). Similarly, Cu(I) complex, {Cu[OC(Me)CHC(Me)N(Ar)]Li[OC(Me)CHC(Me)N(Ar)]}₂ (2) was synthesized by reacting 2 equiv. of Li[OC(Me)CHC(Me)N(Ar)] with CuCl in toluene at room temperature for 12 h. While the reaction of CuCl with Li[OC(Me)CHC(Me)N(Ar)] in the presence of triphenylphosphine in THF solution at room temperature, a three-coordinated Cu[OC(Me)CHC(Me)N(Ar)](PPh₃) (3) can be isolated in high yield. Replacing the PPh₃ of 3 with N-heterocarbene (NHC) generates Cu[OC(Me)CHC(Me)N(Ar)](NHC) (4) in low yield. Complexes 2, 3, and 4 were characterized by ¹H and ¹³C NMR spectroscopies and all molecules were structurally characterized by X-ray diffractometry. Two coordination modes of ketiminate ligands were found in the molecular structure of 2, one of which is copper-coordinated terminal ketiminates and the other is lithium-copper-coordinated bridging ketiminates.     

TLC plates as a convenient platform for solvent-free reactions

Solvent-free oxidative couplings of naphthols have been optimized by co-spotting catalysts and substrates directly on silica TLC plates and heating, followed by chromatography, staining, and qualitative visualization.     

The Influence of Oxygen Plasma on Methylammonium Lead Iodide (MAPbI3) Film Doped with Lead Cesium Triiodide (CsPbI3)

In recent years, the study of organic–inorganic halide perovskite as an optoelectronics material has been a significant line of research, and the power conversion efficiency of solar cells based on these materials has reached 25.5%. However, defects on the surface of the film are still a problem to be solved, and oxygen plasma is one of the ways to passivate surface defects. In order to avoid destroying the methylammonium lead iodide (MAPbI₃), the influence of plasma powers on film was investigated and the cesium triiodide (CsPbI₃) quantum dots (QDs) were doped into the film. In addition, it was found that oxygen plasma can enhance the mobility and carrier concentration of the MAPbI₃ film.     

Relationship between alignment layer polymer surface structures and liquid crystal display parameters

The polar alignment layer (AL) surface provided relatively small liquid crystal (LC) pretilt angles while polyimides with long alkyl side chains gave relatively large LC pretilt angles. The results suggest that LC pretilt angles, in addition to an anchoring effect, are greatly affected by both electronic and steric interactions between LC molecules and a polyimide alignment layer surface. Rubbing with a cotton cloth induces functional groups, side chains, and repeat units at the surface of a liquid crystal polyimide AL to re-orient. It was discovered that rubbing induced polar functional groups and repeat units to re-orient out-of-the-plane of the surface, and it made non-polar aliphatic side chains partially re-orient inwards, toward the bulk of the film.     

Nonlinear Stability of a Self-Similar 3-Dimensional¶Gas Flow

We show that the 3-dimensional supersonic gas flow past an infinite cone is nonlinear staple upon the perturbation of the obstacle. The perturbed flow exists globally in space and tends to the self-similar flow downstream. There is a thin layer of concentration of vorticities and entropy variation. Our analysis is based on an approximation scheme using local self-similar solutions as building blocks. This enables us to obtain global estimates of the nonlinear interactions of waves needed for the stability analysis. Received: 23 November 1998 / Accepted: 26 January 1999     

Exploration of an Efficient Method for Optical Resolution of Etodolac

The exploration of an efficient method for resolving etodolac using either L‐cinchonidinium salt or chiral isopinocamphenol diastereomeric esters is described herein. Furthermore, racemization mechanism of chiral etodolac is rationalized in terms of an isotope labeling experiment.     

Hyperbolic conservation laws with a moving source

The purpose of this paper is to investigate the wave behavior of hyperbolic conservation laws with a moving source. When the speed of the source is close to one of the characteristic speeds of the system, nonlinear resonance occurs and instability may result. We will study solutions with a single transonic shock wave for a general system u_t + f(u)_x = g(x, u). Suppose that the i^th characteristic speed is close to zero. We propose the following stability criteria: Here l_i and r_i are the i^th normalized left and right eigenvectors of , respectively. Through the local analysis on the evolution of the speed and strength of the transonic shock wave, the above criterion can be justified. It turns out that the speed of the transonic shock wave is monotone increasing (decreasing) most of the time in the unstable (stable) case. This is shown by introducing a global functional on nonlinear wave interactions, based on the Glimm scheme. In particular, together with the local analysis, we can study the shock speed globally. Such a global approach is absent in the previous works. Using this strategy, we prove the existence of solutions and verify the asymptotic stability (or instability). © 1999 John Wiley & Sons, Inc.     

Computation of three‐dimensional flow around square and circular piers

The aim of the present study is to investigate, by numerical simulation, the three‐dimensional turbulent flow field around square and circular piers. The numerical model employs a finite volume method based on MacCormack's explicit predictor–corrector scheme to solve weakly compressible hydrodynamic equations for turbulent flow. Computed results are compared with Dargahi's experimental measurements to assess the validity of the proposed model. Very good agreements are obtained. The results of flow simulation indicate that near the upstream face of the pier there exists a downflow, which joins the separated flow to form the horseshoe vortex stretched around the pier. This horseshoe vortex interacts with the wake vortex to create the upflow behind the pier. These phenomena appear to be very important to the mechanism of scouring around the pier. In general, the flow patterns for the square and circular piers are similar. However, the strengths of the downflow and horseshoe vortex are greater in the case of the square pier. The position of the horseshoe vortex around the circular pier is closer to the front face than that around the square pier. In the meantime, the domain of the wake flow in the case of the square pier is greater than that in the case of the circular one. Copyright © 2000 John Wiley & Sons, Ltd.     

The Antileukemic Effect of Xestoquinone,A Marine-Derived Polycyclic Quinone-Type Metabolite,Is Mediated through ROS-Induced Inhibition of HSP-90

Xestoquinone is a polycyclic quinone-type metabolite with a reported antitumor effect. We tested the cytotoxic activity of xestoquinone on a series of hematological cancer cell lines. The antileukemic effect of xestoquinone was evaluated in vitro and in vivo. This marine metabolite suppressed the proliferation of Molt-4, K562, and Sup-T1 cells with IC₅₀ values of 2.95 ± 0.21, 6.22 ± 0.21, and 8.58 ± 0.60 µM, respectively, as demonstrated by MTT assay. In the cell-free system, it inhibited the activity of topoisomerase I (Topo I) and II (Topo II) by 50% after treatment with 0.235 and 0.094 μM, respectively. The flow cytometric analysis indicated that the cytotoxic effect of xestoquinone was mediated through the induction of multiple apoptotic pathways in Molt-4 cells. The pretreatment of Molt-4 cells with N-acetyl cysteine (NAC) diminished the disruption of the mitochondrial membrane potential (MMP) and apoptosis, as well as retaining the expression of both Topo I and II. In the nude mice xenograft model, the administration of xestoquinone (1 μg/g) significantly attenuated tumor growth by 31.2% compared with the solvent control. Molecular docking, Western blotting, and thermal shift assay verified the catalytic inhibitory activity of xestoquinone by high binding affinity to HSP-90 and Topo I/II. Our findings indicated that xestoquinone targeted leukemia cancer cells through multiple pathways, suggesting its potential application as an antileukemic drug lead.