Efficient Perovskite Light-Emitting Diodes Using Polycrystalline Core-Shell-Mimicked Nanograins

Making small nanograins in polycrystalline organic-inorganic halide perovskite (OIHP) films is critical to improving the luminescent efficiency in perovskite light-emitting diodes (PeLEDs). 3D polycrystalline OIHPs have fundamental limitations related to exciton binding energy and exciton diffusion length. At the same time, passivating the defects at the grain boundaries is also critical when the grain size becomes smaller. Molecular additives can be incorporated to shield the nanograins to suppress defects at grain boundaries; however, unevenly distributed molecular additives can cause imbalanced charge distribution and inefficient local defect passivation in polycrystalline OIHP films. Here, a kinetically controlled polycrystalline organic-shielded nanograin (OSN) film with a uniformly distributed organic semiconducting additive (2,2 ',2 ''-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole), TPBI) is developed mimicking core-shell nanoparticles. The OSN film causes improved photophysical and electroluminescent properties with improved light out-coupling by possessing a low refractive index. Finally, highly improved electroluminescent efficiencies of 21.81% ph el(-1) and 87.35 cd A(-1) are achieved with a half-sphere lens and four-time increased half-lifetime in polycrystalline PeLEDs. This strategy to make homogeneous, defect-healed polycrystalline core-shell-mimicked nanograin film with better optical out-coupling will provide a simple and efficient way to make highly efficient perovskite polycrystal films and their optoelectronics devices.

Low temperature growth of amorphous VO2 films on flexible polyimide substrates with a TiO2 buffer layer

Amorphous VO2 thin films were grown on anatase TiO2-buffered polyimide (PI) films using radio-frequency magnetron sputtering deposition with a VO2 target as low as at 175 °C. For comparison, the authors grew VO2 films on TiO2-buffered SiO2/Si substrates. The structural and morphological properties of the VO2 films were evaluated by x-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. VO2 films grown on TiO2/SiO2/Si were crystalline at 200 and 250 °C and were amorphous at 175 °C. VO2 films grown on TiO2/PI were amorphous. No peak corresponding to the monoclinic phase of VO2 appeared in the Raman spectra of VO2/TiO2/PI films grown at 175 or 200 °C. The chemical compositions of VO2 and the binding energy spectra of V and O atoms were probed by x-ray photoelectron spectroscopy. The authors discussed the multivalence states of V atoms and oxygen vacancies based on the x-ray photoemission spectroscopy of crystalline and amorphous VO2 films. The authors obtained the hysteresis curves of the resistivity as a function of temperature for both VO2/TiO2/SiO2/Si and VO2/TiO2/PI films. In addition, the authors measured the reflectivity of VO2/TiO2/PI films below and above the metal-insulator transition temperature using spectroscopic ellipsometry. The reflectivity changed substantially and was comparable to the literature values of well-crystallized VO2 films, even though the ratio of the switching resistivity values was as low as sixty. This work demonstrates that VO2 films grown on plastic films grown at temperatures as low as 175 °C can be applicable as flexible thermochromic films for use in energy-saving windows. © 2018 Author(s)

Beneficial effects of WON-21 on the symptoms of a hangover and identification of active compounds: experimental studies on antioxidant, anti-inflammation, and alcohol-metabolizing enzymes

Abstract Many hangover cure products containing natural ingredients that are also effective against alcohol-related liver damage or improve liver function have recently become available. In addition to curing liver damage, antioxidants, anti-inflammatory agents, and blood ethanol reduction aids are emerging as relief targets that reduce hangover symptoms. We investigated the ameliorating effect of WON-21 herbal medicinal products by studying the mixing ratio of oriental medicine concept with respect to antioxidant potential, anti-inflammation, and aldehyde dehydrogenase (ALDH) and alcohol dehydrogenase (ADH) enzyme activities. WON-21 and its components exerted antioxidant and anti-inflammatory effects. Rutin, taxifolin, and quercetin showed superior antioxidant effects compared to the other components. WON-12 effectively reduced iNOS and COX-2 in LPS-stimulated macrophages. Quercetin and apigenin were 2 compounds effective for the inhibition of iNOS and COX-2. WON-21 and quercetin also significantly increased the activities of ALDH and ADH enzymes in a concentration-dependent manner

The Inhibitory Effect of Ojeoksan on Early and Advanced Atherosclerosis

Atherosclerosis is closely related to vascular dysfunction and hypertension. Ojeoksan (OJS), originally recorded in an ancient Korean medicinal book named “Donguibogam”, is a well-known, blended herbal formula. This study was carried out to investigate the beneficial effects of OJS on atherosclerosis in vitro and in vivo. Western-diet-fed apolipoprotein-E gene-deficient mice (ApoE −/−) were used for this study for 16 weeks, and their vascular dysfunction and inflammation were analyzed. OJS-treated ApoE −/− mice showed lowered blood pressure and glucose levels. The levels of metabolic parameters with hyperlipidemia attenuated following OJS administration. Hematoxylin and eosin (H&E) staining revealed that treatment with OJS reduced atherosclerotic lesions. OJS also suppressed the expression of adhesion molecules and matrix metalloproteinases (MMPs) compared to Western-diet-fed ApoE −/− mice and tumor necrosis factor-alpha (TNF-α)-stimulated human umbilical vein endothelial cells (HUVECs). Expression levels of MicroRNAs (miRNA)-10a, -126 3p were increased in OJS-fed ApoE −/− mice. OJS significantly increased the phosphorylation of endothelial nitric oxide synthase (eNOS) and protein kinase B (Akt), which are involved in nitric oxide (NO) production. OJS also regulated eNOS coupling by increasing the expression of endothelial GTP Cyclohydrolase-1 (GTPCH). Taken together, OJS has a protective effect on vascular inflammation via eNOS coupling-mediated NO production and might be a potential therapeutic agent for both early and advanced atherosclerosis

GC/MS-Based Metabolomics Approach to Evaluate the Effect of Jackyakgamcho-Tang on Acute Colitis

The objective of this study was to examine the effects of Jackyakgamcho-tang (JGT) on acute colitis. GC/MS-based metabolomics and NGS-based metagenomics were applied to investigate the alteration of metabolites and microbiota in an acute colitis model. The severity of acute colitis symptoms was alleviated by JGT treatment. Induction of colitis and JGT treatment changed compositions of gut microbiota and inflammatory cytokine levels (TNF-α and IL-6). They also substantially change metabolites (i.e., lactic acid, linoleic acid, monostearin, and palmitoylglycerol). In addition, some clear correlations were observed among metabolites, cytokine, and microbiota. This study highlights the applicability of metabolomics and metagenomics study for evaluating anti-inflammatory effects of a new functional herbal medicine as a therapeutic agent for acute colitis

Enhancement of Thermoelectric Performance in Na-Doped Pb_0.6Sn_0.4Te_{0.95–<i>x</i>}Se_<i>x</i>S_0.05 via Breaking the Inversion Symmetry, Band Convergence, and Nanostructuring by Multiple Elements Doping

Topological insulators have attracted much interest in topological states of matter featuring unusual electrical conduction behaviors. It has been recently reported that a topological crystalline insulator could exhibit a high thermoelectric performance by breaking its crystal symmetry via chemical doping. Here, we investigate the multiple effects of Na, Se, and S alloying on thermoelectric properties of a topological crystalline insulator Pb_0.6Sn_0.4Te. The Na doping is known to be effective for breaking the crystalline mirror symmetry of Pb_0.6Sn_0.4Te. We demonstrate that simultaneous emergence of band convergence by Se alloying and nanostructuring by S doping enhance the power factor and decrease lattice thermal conductivity, respectively. Remarkably, the high power factor of 22.3 μW cm^–1 K^–2 at 800 K is achieved for Na 1%-doped Pb_0.6Sn_0.4Te_0.90Se_0.05S_0.05 mainly due to a relatively high Seebeck coefficient via band convergence by Se alloying as well as the suppression of bipolar conduction at high temperatures by the increase of energy band gap. Furthermore, the lattice thermal conductivity is significantly suppressed by PbS nanoprecipitates without deteriorating the hole carrier mobility, ranging from 0.80 W m^–1 K^–1 for Pb_0.6Sn_0.4Te to 0.17 W m^–1 K^–1 at 300 K for Pb_0.6Sn_0.4Te_0.85Se_0.10S_0.05. As a result, the synergistically combined effects of breaking the crystalline mirror symmetry of topological crystalline insulator, band convergence, and nanostructuring for Pb_0.6Sn_0.4Te_{0.95–<i>x</i>}Se_<i>x</i>S_0.05 (<i>x</i> = 0, 0.05, 0.1, 0.2, and 0.95) give rise to an impressively high <i>ZT</i> of 1.59 at 800 K for <i>x</i> = 0.05. We suggest that the multiple doping in topological crystalline insulators is effective for improving the thermoelectric performance

SARS-CoV-2 shedding dynamics and transmission in immunosuppressed patients

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern have been emerging. However, knowledge of temporal and spatial dynamics of SARS-CoV-2 is limited. This study characterized SARS-CoV-2 evolution in immunosuppressed patients with long-term SARS-CoV-2 shedding for 73-250 days, without specific treatment. We conducted whole-genome sequencing of 27 serial samples, including 26 serial samples collected from various anatomic sites of two patients and the first positive sample from patient 2&apos;s mother. We analysed the intrahost temporal dynamics and genomic diversity of the viral population within different sample types. Intrahost variants emerging during infection showed diversity between individual hosts. Remarkably, N501Y, P681R, and E484K, key substitutions within spike protein, emerged in vivo during infection and became the dominant population. P681R, which had not yet been detected in the publicly available genome in Korea, appeared within patient 1 during infection. Mutually exclusive substitutions at residues R346 (R346S and R346I) and E484 (E484K and E484A) of spike protein and continuous turnover of these substitutions occurred. Unique genetic changes were observed in urine samples. A household transmission from patient 2 to his mother, at least 38 days after the diagnosis, was characterized. Viruses may differently mutate and adjust to the host selective pressure, which could enable the virus to replicate efficiently for fitness in each host. Intrahost variants could be candidate variants likely to spread to the population eventually. Our findings may provide new insights into the dynamics of SARS-CoV-2 in response to interactions between the virus and host.N