Photoluminescence from Two-Phase Nanocomposites Embedded in Polymers.

A set of polymer-embedded, two-colored nanocomposites were prepared where the co-existing emission peaks (~578 nm and ~650 nm) had different ratios at their emission thresholds. The nanocomposite samples were simultaneously excited by a 405 nm laser, and the growth of photoluminescence intensities was studied as a function of excitation intensity. The two peaks showed different growth evolution mechanisms. The factors impacting this difference could be (1) energy transfer between the two sized nanoparticles; (2) relaxation mechanism of smaller nanoparticles; and (3) material properties of the polymer.

Substrate and Excitation Intensity Dependence of Saturable Absorption in Perovskite Quantum Dot Films.

Saturable absorption in perovskite quantum dot (PQD) films, leading to saturation in photoluminescence (PL), is reported. PL of drop-casting films was used to probe how excitation intensity and host-substrate influence the growth of PL intensity. The PQD films were deposited on single-crystal GaAs, InP, Si wafers and glass. Saturable absorption was confirmed through PL saturation in all films, with different excitation intensity thresholds, suggesting strong substrate-dependent optical properties, resulting from absorption nonlinearities in the system. The observations extend our former studies (Appl. Phys. Lett., 2021, 119, 19, 192103), wherein we pointed out that the PL saturation in QDs can be used to create all-optical switches in combination with a bulk semiconductor host.

Probing shock-induced structural changes in GaSb.

Laser-driven hypervelocity impact experiments were used to study pressure-induced long-term effects on the crystal structure of undoped GaSb. X-ray diffraction and confocal micro-Raman spectra were collected on unshocked and shock-compressed samples, with corresponding pressures ranging between 8 and 23 GPa. GaSb retained bulk crystallinity at 8 GPa but showed localized site disordering, transformed into an amorphous state at 13 GPa, and stayed in that phase until 23 GPa.

Children And Adolescents With Irritable Bowel Syndrome: Treatment And Management.

BACKGROUND: Irritable bowel syndrome (IBS) is a disorder that causes stomach pain in children and adolescents. It may also impact one's quality of life. IBS is linked to gastrointestinal issues such as diarrhoea and constipation. Despite the identification of several potential pathophysiological pathways, the aetiology of IBS remained unknown. OBJECTIVE: The aim of this paper is to discuss the diagnosis, pathogenesis, case studies and treatment of Irritable bowel syndrome in children and adolescents. METHOD: This systematic review covered relevant papers from the previous ten years that were accessible in Science Direct, Elsevier, NCBI, and Web of Science related to the pathophysiology and function of pharmacological drugs such as antidepressants, antispasmodics, prokinetics, and antibiotics in children with irritable bowel syndrome. RESULT: Only a few prospective therapy techniques have been investigated in children, and even fewer of those have been demonstrated to be effective. This article presents case studies including 50-59 children, which demonstrate a favourable acceptable impact that is more effective than a placebo in terms of reducing symptoms and improving the overall quality of life in children who have irritable bowel syndrome. Furthermore, the majority of the pathophysiological explanations and treatment options discussed are based on adult studies. These major issues arose when treating paediatric IBS, and they must be addressed in order to properly treat children with IBS. Trials that focus on many combinations of pharmacological and non-pharmacological therapies seem to be more helpful. DISCUSSION: In recent years, a number of systematic reviews have been conducted to evaluate the efficacy of medication treatments in children for IBS; however, the dependability of these systematic reviews needs to be further investigated owing to the various experimental designs and levels of evidence used. This article highlights paediatric therapy options, including pharmaceutical medications such as antidepressants, antispasmodics, prokinetics, and antibiotics. The goal is to alleviate IBS symptoms while also enhancing the quality of life for children with this illness.

Cyclic GAN Model to Classify Breast Cancer Data for Pathological Healthcare Task.

An algorithm framework based on CycleGAN and an upgraded dual-path network (DPN) is suggested to address the difficulties of uneven staining in pathological pictures and difficulty of discriminating benign from malignant cells. CycleGAN is used for color normalization in pathological pictures to tackle the problem of uneven staining. However, the resultant detection model is ineffective. By overlapping the images, the DPN uses the addition of small convolution, deconvolution, and attention mechanisms to enhance the model's ability to classify the texture features of pathological images on the BreaKHis dataset. The parameters that are taken into consideration for measuring the accuracy of the proposed model are false-positive rate, false-negative rate, recall, precision, and F1 score. Several experiments are carried out over the selected parameters, such as making comparisons between benign and malignant classification accuracy under different normalization methods, comparison of accuracy of image level and patient level using different CNN models, correlating the correctness of DPN68-A network with different deep learning models and other classification algorithms at all magnifications. The results thus obtained have proved that the proposed model DPN68-A network can effectively classify the benign and malignant breast cancer pathological images at various magnifications. The proposed model also is able to better assist the pathologists in diagnosing the patients by synthesizing the images of different magnifications in the clinical stage.

Microscopic description and uncertainty of the Stokes shift in semiconductors.

Using GaAs as a test material, we investigated the redshift between emission and the optical bandgap. The knowledge of the energy difference, referred to as the Stokes shift, is of considerable importance for solid-state light sources because its magnitude defines the centered monochromaticity of the emission. Employing Fan's theory, we reveal the basic parameters, which determine the Stokes shift, and provide an uncertainty analysis, considering both uncorrelated and correlated variables. We disclose that the considerable scatter of the dielectric constants in the literature causes uncertainties comparable to or even exceeding the mean. The work stresses that the high-frequency and static dielectric constants might be closer than the currently promoted numbers.

Ethylenediamine Catalyzes Nitromethane Shock-to-Detonation in Two Distinct Ways.

Adding amines to liquid nitromethane (NM) is known to lower the threshold for the shock-to-detonation transition because amines catalyze proton transfer reactions that are the initial steps in the energy release process. We studied NM with 1 wt % ethylenediamine (NM/EDA) with 4 ns input shocks using time and space resolved diagnostics: photon Doppler velocimetry (PDV), optical pyrometry, and nanosecond video imaging. The 4 ns shocks are fast enough to time-resolve the reaction kinetics and the shock-to-detonation transition. We find that it is possible to shock ignite the NM/EDA without producing a detonation, so there is more to amine sensitization of the shock-to-detonation process than simply lowering the barrier to initial reactions. We find that although 1 wt % EDA has little effect on the ambient properties of NM, it dramatically alters the Hugoniot. The shock speed in NM/EDA is reduced, indicating that shocked NM/EDA is significantly more compressible than NM. Higher compressibility is associated with greater adiabatic heating, so EDA both lowers the barrier to proton transfer reactions and increases shock energy absorption. To explain the enhanced compressibility, we propose that shocking NM/EDA produces a reactive flow that has a much higher ionic strength than in NM. The sudden transformation from a molecular liquid to an ionic liquid with stronger intermolecular interactions is responsible for enhanced compressibility and shock heating.

Optical Bandgap Definition via a Modified Form of Urbach's Rule.

We are reporting an esoteric method to determine the optical bandgap of direct gap materials by employing Urbach's rule. The latter, which describes the slope of the band tail absorption in semiconductors, in its original version, cannot be employed to pinpoint the optical bandgap. Herein, however, we show that a modified form of Urbach's rule defines the optical bandgap, and therefore, enables the accurate determination of the optical bandgap energy, which turns out to be identical with the threshold energy for the band tail absorption. The model further produces an explicit expression for the absorption coefficient at the optical bandgap energy.

Inherent photoluminescence Stokes shift in GaAs.

The intrinsic photoluminescence Stokes shift, i.e., the energy difference between optical band gap and emission peak, of 350 µm thick semi-insulating GaAs wafers is found to be 4 meV at room temperature. The result is based on the determination of the optical bulk band gap from the transmission trend via modified Urbach rule whose result is confirmed with the transmission derivative method. The findings reveal the detailed balance of the optically evoked transitions and disclose the intrinsic link between Stokes shift and the Urbach tail slope parameter.