Manipulating Ion Migration for Highly Stable Light-Emitting Diodes with Single-Crystalline Organometal Halide Perovskite Microplatelets

Ion migration has been commonly observed as a detrimental phenomenon in organometal halide perovskite semiconductors, causing the measurement hysteresis in solar cells and ultrashort operation lifetimes in light-emitting diodes. In this work, ion migration is utilized for the formation of a p-i-n junction at ambient temperature in single-crystalline organometal halide perovskites. The junction is subsequently stabilized by quenching the ionic movement at a low temperature. Such a strategy of manipulating the ion migration has led to efficient single-crystalline light-emitting diodes that emit 2.3 eV photons starting at 1.8 V and sustain a continuous operation for 54 h at ∼5000 cd m^–2 without degradation of brightness. In addition, a whispering-gallery-mode cavity and exciton–exciton interaction in the perovskite microplatelets have both been observed that can be potentially useful for achieving electrically driven laser diodes based on single-crystalline organometal halide perovskite semiconductors

The Mechanism and Fine-Tuning of Chiral Plexcitons in the Strong Coupling Regime

Chiral plexcitons, produced by the strong interaction between plasmonic nanocavities and chiral molecules, can provide a promising direction for controlling chiroptical responses on the nanoscale. Here, we reveal the chiral origin and electromagnetic hybridization process in chiral strongly coupled systems. The mechanism and unique advantages of chiral plexcitons for fine-tuning circular dichroism (CD) responses are demonstrated, providing a rule for controlling chiral light–matter interactions in complex chiral nanosystems. Furthermore, we experimentally demonstrate the fine-tuning of chiral plexcitons in hybrid systems consisting of plasmonic nanoparticles and chiral J-aggregates. Continuous and precise tuning of the CD resonance positions was successfully achieved in a given structure. Compared with the previous work, the CD spectral tuning accuracy has been improved by an order of magnitude, which can reach the level of 1 nm. Our findings provide a feasible strategy and theoretical basis for accurately controlling chirality in multiple dimensions

Junction Propagation in Organometal Halide Perovskite–Polymer Composite Thin Films

With the emergence of organometal halide perovskite semiconductors, it has been discovered that a p–i–n junction can be formed in situ due to the migration of ionic species in the perovskite when a bias is applied. In this work, we investigated the junction formation dynamics in methylammonium lead tribromide (MAPbBr₃)/polymer composite thin films. It was concluded that the p- and n- doped regions propagated into the intrinsic region with an increasing bias, leading to a reduced intrinsic perovskite layer thickness and the formation of an effective light-emitting junction regardless of perovskite layer thicknesses (300 nm to 30 μm). The junction propagation also played a major role in deteriorating the LED operation lifetime. Stable perovskite LEDs can be achieved by restricting the junction propagation after its formation

Survival rates and mycobacterial burden in the lung and spleen.

<p>Animals were infected with 25 colony-forming units of <i>M</i>.<i>tb</i> Erdman strain. Group coloring in the survival graph is maintained throughout the article for comparability of data. One animal in BCG/Ad(im) group died accidently and is excluded from data analysis (<b>A</b>). Overall log-rank test for trend yielded p = 0.0247, but no statistical differences between groups. Colony-forming units (CFU) of mycobacteria was measured per gram of randomly selected tissue from different lung lobs or spleen at necropsy. CFU per right lung (<b>B</b>), left lung (<b>C</b>) and spleen (<b>D</b>) were presented in logarithmic numbers. P-values above lines indicate comparison between groups. Mann-Whitney rank test is used to compare differences relative to naïve group.</p

Single-Layer Halide Perovskite Light-Emitting Diodes with Sub-Band Gap Turn-On Voltage and High Brightness

Charge-carrier injection into an emissive semiconductor thin film can result in electroluminescence and is generally achieved by using a multilayer device structure, which requires an electron-injection layer (EIL) between the cathode and the emissive layer and a hole-injection layer (HIL) between the anode and the emissive layer. The recent advancement of halide perovskite semiconductors opens up a new path to electroluminescent devices with a greatly simplified device structure. We report cesium lead tribromide light-emitting diodes (LEDs) without the aid of an EIL or HIL. These so-called single-layer LEDs have exhibited a sub-band gap turn-on voltage. The devices obtained a brightness of 591 197 cd m^–2 at 4.8 V, with an external quantum efficiency of 5.7% and a power efficiency of 14.1 lm W^–1. Such an advancement demonstrates that very high efficiency of electron and hole injection can be obtained in perovskite LEDs even without using an EIL or HIL

Additional file 1: of Multilocus genotyping of Giardia duodenalis isolates from children in Oromia Special Zone, central Ethiopia

Summary of the target genes, primers and annealing temperature of G. duodenalis used in this study. (DOCX 15 kb

AdHu5Ag85A Respiratory Mucosal Boost Immunization Enhances Protection against Pulmonary Tuberculosis in BCG-Primed Non-Human Primates

<div><p>Persisting high global tuberculosis (TB) morbidity and mortality and poor efficacy of BCG vaccine emphasizes an urgent need for developing effective novel boost vaccination strategies following parenteral BCG priming in humans. Most of the current lead TB vaccine candidates in the global pipeline were developed for parenteral route of immunization. Compelling evidence indicates respiratory mucosal delivery of vaccine to be the most effective way to induce robust local mucosal protective immunity against pulmonary TB. However, despite ample supporting evidence from various animal models, there has been a lack of evidence supporting the safety and protective efficacy of respiratory mucosal TB vaccination in non-human primates (NHP) and humans. By using a rhesus macaque TB model we have evaluated the safety and protective efficacy of a recombinant human serotype 5 adenovirus-based TB vaccine (AdHu5Ag85A) delivered via the respiratory mucosal route. We show that mucosal AdHu5Ag85A boost immunization was safe and well tolerated in parenteral BCG-primed rhesus macaques. A single AdHu5Ag85A mucosal boost immunization in BCG-primed rhesus macaques enhanced the antigen–specific T cell responses. Boost immunization significantly improved the survival and bacterial control following <i>M</i>.<i>tb</i> challenge. Furthermore, TB-related lung pathology and clinical outcomes were lessened in BCG-primed, mucosally boosted animals compared to control animals. Thus, for the first time we show that a single respiratory mucosal boost immunization with a novel TB vaccine enhances protection against pulmonary TB in parenteral BCG-primed NHP. Our study provides the evidence for the protective potential of AdHu5Ag85A as a respiratory mucosal boost TB vaccine for human application.</p></div

Clinical outcomes post-AdHu5Ag85A boost vaccination.

<p>Note: compared to naïve and BCG alone groups.</p><p>*Taken 6 weeks post AdHu5Ag85A boost immunization.</p><p>Clinical outcomes post-AdHu5Ag85A boost vaccination.</p

Antigen-specific IFN-γ+ T cell responses post-BCG vaccination or post-BCG prime-Ad boost vaccination.

<p>Antigen-specific IFN-γ+ T cell responses in non-boosted BCG-primed animals are measured using IFN- γ ELISOPT assay at 0wk, 13wk and 17wk post BCG vaccination by stimulating fresh peripheral blood mononuclear cells (PBMC) with PPD for 24h (<b>A</b>). Scatter dotplot depicting spot forming cells/million PBMC representing the mean responses±standard error. P-values are relative to the time point before BCG vaccination (0wk). (<b>B/C/D</b>) depicts antigen-specific IFN-γ responses for each group measured using IFN-γ ELISOPT assay before vaccination (wk0) and after BCG priming (BCG) or after BCG priming and AdHu5Ag85A boosting BCG/Ad(it), BCG/Ad(aerosol), (BCG/Ad(im). Fresh PBMCs are stimulated with PPD (<b>B</b>) or rAg85A (<b>C</b>) or single pool (<b>D</b>) and scatter dotplot depicting mean of spot forming cells/million PBMC ± standard error. P-values above lines indicate comparison between groups. Wilcoxon signed rank test was used to compare measurements at different time points of same animal.</p

Experimental schema and plan.

<p>Depicting the timelines of vaccination (BCG priming at wk0 and AdHu5Ag85A boosting at wk14), <i>M</i>.<i>tb</i> infectious challenge (wk20) and fixed endpoint/autopsy (wk38). Scheduled times for clinical signs, blood work for acute phase protein measurement, chest X-ray and immune monitoring are indicated. Timelines during infection phase are referred relative to the 18 weeks post-challenge timepoint (indicated within parentheses).</p