Strongly Luminescent Dion–Jacobson Tin Bromide Perovskite Microcrystals Induced by Molecular Proton Donors Chloroform and Dichloromethane

Lead-free 2D perovskites based on tin halide octahedron slabs with Dion–Jacobson (DJ) phases have drawn attention due to their improved stability; still, reports on light-emitting DJ lead-free perovskites are scarce. Herein, a room-temperature ligand assisted re-precipitation method is used to produce ODASnBr₄ perovskite microcrystals (ODA denotes protonated 1,8-octanediamine). After incorporating molecular dopants chloroform and dichloromethane, not only the crystallinity of the DJ perovskite phase improves, but their emission becomes much stronger due to the formation of hydrogen bonds between [SnBr₆]⁴⁻ octahedra and acidic C H proton donors. ODASnBr₄ microcrystals doped with these molecules show a high photoluminescence quantum yield (PLQY) approaching 90%, and their emission remains stable under a continuous UV irradiation, with less than 10% loss in intensity over 6 h. Moreover, by tuning the pristine ODASnBr₄ with various degrees of exposure to the molecular dopants, the maximum of their self-trapped exciton emission can be fine-tuned over a spectral range of 570–608 nm while maintaining high PLQYs of 83–88%. This provides a convenient way to adjust the spectral position of DJ perovskite emission without changing halides or A-site spacers. Thus, stable and strongly emitting lead-free DJ perovskite materials have been developed.     

Software reliability growth supermodels

The aim of this paper is to present a method for obtaining a more accurate prediction for software reliability growth models (SRGMs). It is our belief that if we try to use a more general approach implying the building of a supermodel as a weighted sum of several SRGMs, it may be possible to obtain more accurate results in prediction. The weight factors will depend on the values of the prequential likelihood functions as calculated for each SRGM, the values varying each time a new error is observed. The basic models chosen are the Jelinski-Moranda, Goel-Okumoto, Duane, Littlewood-Verrall and Keiller-Littlewood models. Finally, we shall compare the SRGMs with the supermodels by using the median estimate and deciding if there are any benefits or constraints in applying this technique.     

A review on solid oxide derived from waste shells as catalyst for biodiesel production

The waste eggs and mollusk shells are found to be the richest sources of calcium carbonate and have been utilized for various purposes after proper treatments. When calcined at a proper temperature calcium carbonate converts into CaO, which is a metal oxide. Researchers have found that the CaO prepared from the waste shells can be used as catalyst in biodiesel production process. Utilization of waste shells as a source of CaO not only gives an opportunity to use it as catalyst but also adds value to the waste generated. In this paper a brief discussion with recent development on biodiesel production using waste shell derived solid oxide as catalyst is presented.     

T lymphocytes in allergic inflammation

T lymphocytes are the crucial cells in immunopathogenesis of allergic diseases since they regulate the occurrence of allergic sensitisation, synthesis of immunoglobulin E and allergic inflammation. The importance of lymphocyte T is reflected on the fact that after activation by a specific antigen they are able to produce different cytokines responsible for activation and aggregation of specific inflammatory cells in target tissues, promoting the occurrence and maintenance of allergic inflammation. Discovery of functional dichotomy of activated lymphocytes T CD4+ capable of suppressing synthesis of immunoglobulin E (Th1) or stimulate immunoglobulin E and allergic inflammation (Th2) is an important element in elucidation of pathogenesis of allergic inflammation and inadequate synthesis of immunoglobulin E. The immunoglobulin synthesis is regulated by a complex combination of factors and signals where lymphocytes CD4+ play the central regulatory role.     

Flux recovery of tubular ceramic membranes fouled with whey proteins

Membrane process efficiency is governed by the formation of fouling deposits during processing of dairy fluids. Because of fouling with whey proteins, permeate flux can drastically decline during filtration process. This paper describes the flux recovery procedure for ceramic tubular membranes (50 and 200 nm pore sizes) fouled with whey proteins. The results comprehend the effect of rinsing and cleaning agent choice and concentration, on the cleaning efficiency. As chemical cleaning agents, the caustic solution and the commercial detergents P3-ultrasil 67 and P3-ultrasil 69 were selected. The observations are that rinsing with deionised water contributes to a flux recovery to a certain degree. For the 50 nm membrane, the choice of the 1.0% (w/w) caustic solution, as cleaning agent, gives the best flux recovery. For the 200 nm, total flux recovery was not observed regardless of the cleaning agent choice and concentration. Cleaning with chosen commercial detergent appeared to be less efficient than cleaning with caustic solution for the chosen ceramic membranes. Also, a mathematical model, proposed in this study, has shown high agreement with experimentally obtained data.     

Undoped p‐Type ZnO Nanorods Synthesized by a Hydrothermal Method

Zinc oxide is a very promising material for short‐wavelength light‐emitting devices due to its large band gap and high exciton binding energy. Although great progress has been made in recent years, p‐type doping and control over native defects introduced during or after material growth are still significant problems that hinder the development of efficient ZnO based optoelectronic devices. Here we demonstrate a versatile method for the growth or p‐type or n‐type ZnO nanorods from the same growth solution at temperature as low as 90 °C, where the conductivity type is controlled by the preparation of the seed layer for nanorod growth. The differences in the conductivity type can be attributed to dependency of native defect concentrations and hydrogen incorporation on the seed layer preparation method. Room temperature electroluminescence has been demonstrated from homojunction and heterojunction light emitting diodes containing p‐ZnO nanorods.     

Effect of sucrose concentration on the products of Kombucha fermentation on molasses

Fermentation of 1.5 g/l of Indian black tea, sweetened with adequate quantities of molasses (containing approx. 70 g/l, 50 g/l and 35 g/l of sucrose), was conducted using domestic Kombucha. Inoculation was performed with 10% of fermentation broth from a previous process. The fermentation in cylindrical vessels containing 2 l of liquid phase, was carried out at 22 ± 1 °C for 14 days, with periodical sampling, to measure pH, content of acids (total, acetic and l-lactic), content of remaining sucrose, and the yield of biomass at the end of fermentation. A product with 70 g/l sucrose from molasses corresponds to an optimal concentration of carbon source, which provided metabolites with high pH, a low content of less desired acetic acid, a high content of highly desired l-lactic acid, an acceptable content of total acids and the highest possible level of utilisation of sucrose.     

The algorithm for directional element without dead tripping zone based on digital phase comparator

This paper describes the algorithm for directional element without dead tripping zone. Instead of calculating phase angle between the phasors of voltage and current the algorithm uses digital phase comparator. The procedure is based on calculation of normalized average power within one semi-period of the input voltage and current signals. Before usage the samples are passed through the Fourier filter to remove high-order harmonics and/or direct component. The dead tripping zone is eliminated by introduction of a voltage delay which is used for determination of direction. In addition, special attention is paid to the problem of synchronization which appears when signal frequency deviates from the assumed value. Sensitivity of the algorithm can be easily adjusted in accordance with the parameters of the network in which a directional element is used. Performances of the method are tested by several computer-generated signals. Since the calculations used in this algorithm are based on simple mathematical operations, the high speed of operation is achieved.     

Mechanisms of Antibacterial Activity of MgO: Non‐ROS Mediated Toxicity of MgO Nanoparticles Towards Escherichia coli

The toxicity of metal oxide nanomaterials and their antimicrobial activity is attracting increasing attention. Among these materials, MgO is particularly interesting as a low cost, environmentally‐friendly material. The toxicity of MgO, similar to other metal oxide nanomaterials, is commonly attributed to the production of reactive oxygen species (ROS). We investigated the toxicity of three different MgO nanoparticle samples, and clearly demonstrated robust toxicity towards Escherichia coli bacterial cells in the absence of ROS production for two MgO nanoparticle samples. Proteomics data also clearly demonstrate the absence of oxidative stress and indicate that the primary mechanism of cell death is related to the cell membrane damage, which does not appear to be due to lipid peroxidation.