Efficient cathode contacts through Ag-doping in multifunctional strong nucleophilic electron transport layer for high performance inverted OLEDs

This paper presents an efficient and stable green inverted organic light emitting diode (IOLED) using multifunctional and strong nucleophilic quality electron transport material (1,3-bis(2-phenyl-1,10-phenanthrolin-4-yl)benzene (m-bPPhenB)) with silver (Ag) as an n-dopant. By the energy level alignment study using in-situ ultraviolet photoelectron spectroscopy measurement, negligible electron injection barrier between indium tin oxide (ITO) and Ag-doped m-bPPhenB (Φ_e ≈ 0.03 eV) is observed and the electrons can be easily tunneled from ITO into Ag-doped m-bPPhenB layer. Also, Ag dopant forms coordination bonds with phenanthroline based unit, which improves electron injection from ITO. Fabricated IOLED devices using an Ag-doped m-bPPhenB have an extremely low driving voltage of 3.6 V and external quantum efficiency of 29.0%. Such good performances of IOLED are attributed to negligible electron injection barrier at the interface between ITO and Ag-doped m-bPPhenB. The Ag-doped IOLED device also shows a good air stability owing to the stable Ag n-dopant. The doping of Ag into special electron transport layer in the IOLED structure could be applicable to various displays and lighting applications.     

Greener synthesis using hydrogen peroxide in ethyl acetate of alicyclic ring-fused benzimidazoles and anti-tumour benzimidazolequinones

Environmentally-friendly and cost effective hydrogen peroxide in ethyl acetate was used to prepare in high yields pyrrolo[1,2-a]benzimidazoles from commercial o-(pyrrolidin-1-yl)anilines without the requirement for organic-aqueous extraction and chromatography. Six, seven and eight membered ring-fused analogues were similarly obtained in high yields with methanesulfonic acid required for the pyrido[1,2-a]benzimidazole. Anti-tumour benzimidazolequinone derivatives were obtained in high yield via the cyclization of 3,6-dimethoxy-2-(cycloamino)anilines.     

Iron oxide nanoparticles synthesized by controlled bio-precipitation using leaf extract of Garlic Vine (Mansoa alliacea)

Iron (III) oxide nanoparticles were synthesized through green chemistry by the controlled reduction of hepta hydrous iron sulphate using the leaf extract of Garlic Vine. The crystalline phase of trivalent iron embedded in the primitive lattice of hexagonal β-Fe₂O₃ was obtained under the space group P3 (143). The scattered lines and considerably broadened peaks in the x-ray diffraction pattern indicate that the samples formed are crystallites of nano regime rather than bulk or amorphous in nature. Further, the size and the microstrain of the nanocrystallites were estimated through Hall Williamson analysis. The abundance of elemental iron present in the sample was estimated through Atomic Absorption Spectroscopy, whilst the UV visible analysis and FT-IR measurements, in accordance with XRD result, endorsed the formation of iron (III) oxide nanocrystals with iron predominantly occupying the octahedral sites. The band gap energy (2.84 eV) corresponds to the best fit is found to be for indirect allowed semiconducting transition between valance and conduction bands. Further, the TGA measurements were performed to identify the presence of capped polymer over the surface of nanoparticles, the organic decomposition temperature and phase transformation of meta-stable β-Fe₂O₃ to stable α-Fe₂O₃ at temperature above 500 °C.     

Silver nanoparticles and silver ions stabilized in NaCl nanocrystals

This study presents a two-step synthesis of nanoparticles and the stabilization process of Ag ions in the matrix of NaCl nanocrystals. Ag⁺ ions are incorporated to NaCl with a new and attractive method that can be easily used for the different types of alkaline halides. The nanoparticles with predominant size found between 10 and 15 nm were stabilized on the surface and/or interior of NaCl nanocrystals using, in the first stages, the ionic-exchange property of zeolite A4. The optical properties of the materials were characterized through optical absorption, leading to well defined absorption bands located in the wave length values between 217–275 nm and 350–770 nm approximately, for Ag⁺ and AgNp, respectively. The antibacterial property of Ag ions and nanoparticles stabilized in NaCl was analyzed against gram-negative Escherichia Coli and Klebsiella bacteria. In order to quantify the antibacterial effect of Ag ions and nanoparticles the inhibition ratio was used as a parameter on the bacteria colonies grown in culture medium by conventional methods. Ag⁺ ions that were stabilized in NaCl nanocrystals show a mayor inhibition ratio in contact with Klebsiella bacteria, conversely Ag nanoparticles showed better results in contact with E. coli.     

[bmIm]OH: an efficient basic catalyst for the synthesis of 4H-benzo[d][1,3-]oxazin-4-one derivatives in solvent-free conditions

Reusable [bmIm]OH was found to be a highly efficient renewable homogenous catalyst for the rapid and convenient synthesis of benzoxazine-4-one derivatives from o-iodobenzoic-acid and benzonitrile at 75 °C in moderate to good yields. This methodology provides a facile and straightforward path to construct other related heterocycles in an eco-compatible fashion.     

Liouville–Green (WKB) asymptotics for almost-diagonal linear second-order matrix difference equations

A Liouville–Green (or WKB) asymptotic approximation theory is developed for a class of almost-diagonal (‘asymptotically diagonal’) linear second-order matrix difference equations. Rigorous and explicitly computable bounds for the error terms are obtained, the asymptotics being made with respect to both, the index and some parameter affecting the equation. The case of the associated inhomogeneous equations is also considered in detail. Some examples and a number of applications are presented for the purpose of illustration.     

海蛎壳粉废弃物负载CuCl_2作为高效、廉价以及可回收催化剂合成炔胺类化合物(英文)

发展了一种经济、简单的海蛎壳粉负载的CuCl2异相催化剂OSP-CuCl2,用来催化醛-炔-胺之间的A3偶联反应.OSP-CuCl2容易通过简单的方法从海蛎壳粉以及CuCl2制备,且显示出高的催化活性以及良好的可循环回收性.在微波辅助以及无溶剂条件下,以OSP-CuCl2为催化剂,能够以高产物收率制备出一系列炔胺类化合物.OSP-CuCl2可通过简单的过滤方式进行回收,并至少可循环使用6次.初步放大实验表明,炔胺类化合物能够以150 mmol的规模制备(87%收率).     

Influence of the applied charge on the electro-chemical degradation in green phosphorescent organic light emitting diodes

The influence of the current density on the chemical degradation processes of a phosphorescent OLED based on Ir(ppy)₃ emitter is investigated by laser-desorption/ionization time-of-flight mass spectrometry. Comparing the mass spectra collected for unaged and aged OLEDs, the formation of different chemical degradation products could be detected and are identified as dimer and trimer products of BPhen as well as Cs-adducts of these polymers and the well-known emitter-BPhen-adduct ([Ir(ppy)₂BPhen]⁺). In this work, we will show that the formation of [Ir(ppy)₂BPhen]⁺ depends strongly on the amount of the charge flowing through the device, where the other degradation products show a much different behaviour.     

Mathematical attitudes and semantic differentials

The semantic differential—one approach to attitude measurement— basically records a combination of a person's associations with a particular concept with a scaling procedure. This paper considers the implications of such a device for teachers of mathematics.     

Brownian motion with drift on spaces with varying dimension

Many properties of Brownian motion on spaces with varying dimension (BMVD in abbreviation) have been explored in Chen and Lou (2018). In this paper, we study Brownian motion with drift on spaces with varying dimension (BMVD with drift in abbreviation). Such a process can be conveniently defined by a regular Dirichlet form that is not necessarily symmetric. Through the method of Duhamel’s principle, it is established in this paper that the transition density of BMVD with drift has the same type of two-sided Gaussian bounds as that for BMVD (without drift). As a corollary, we derive Green function estimate for BMVD with drift.