Optical power degradation mechanisms in 271†nm AlGaN-based deep ultraviolet light-emitting diodes.

The degradation of AlGaN-based UVC LEDs under constant temperature and constant current stress for up to 500 hrs was analyzed in this work. During each degradation stage, the two-dimensional (2D) thermal distributions, I-V curves, optical powers, combining with focused ion beam and scanning electron microscope (FIB/SEM), were thoroughly tested and analyzed the properties and failure mechanisms of UVC LEDs. The results show that: 1) the opto-electrical characteristics measured before/during stress indicate that the increased leakage current and the generation of stress-induced defects increase the non-radiative recombination in the early stress stage, resulting in a decrease in optical power; 2) the increase of temperature caused by the deterioration of the Cr/Al layer of p-metal after 48 hrs of stress aggravates the optical power in UVC LEDs. The 2D thermal distribution in conjunction with FIB/SEM provide a fast and visual way to precisely locate and analyze the failure mechanisms of UVC LEDs.

Defects dynamics during ageing cycles of InGaN blue light-emitting diodes revealed by evolution of external quantum efficiency--current dependence.

We report in detail the defect dynamics in the active region by monitoring the external quantum efficiency (EQE) - injection current curves, I-V curves, and electroluminescence spectra during the ageing test, under a forward current of 850 mA (85 A/cm2), room temperature. We apply a two-level model to analyze the EQE curves and the electroluminescence spectra. The results suggest that high injection density during the ageing may reduce the density of the Shockley-Reed-Hall nonradiative recombination centers and enhance the carrier mobility and diffusion length. The former effect would directly lead to initial surge of EQE, whereas the latter would enhance the effect of extended defects which leads to reduction in peak EQE and increase in EQE droop rate.

Tumor-associated macrophages promoting PD-L1 expression in infiltrating B cells through the CXCL12/CXCR4 axis in human hepatocellular carcinoma.

The inflammation-related tumor microenvironment (TME) is one of the major driving forces of hepatocarcinogenesis. We aimed to investigate cell-to-cell communication among Hepatocellular Carcinoma (HCC) through re-analyzing HCC single-cell RNA-seq data, and to confirm such cellular interaction through in vitro and in vivo study. We found a subset of Regulatory B cells with PD-L1 expression (PD-L1+ Bregs), mainly located in adjacent HCC tissues. In co-localization with PD-L1+ Bregs, a subset of Tumor Associated Macrophages with high expression of CXCL12 (CXCL12+ TAMs) was also mainly located in adjacent HCC tissues. Moreover, CXCL12+ TAMs can be stimulated in vitro using an HCC conditional medium. Using CellChat analysis and Multiplex Immunohistochemistry staining (mIHC), CXCL12+ TAMs were found to be first recruited by Cancer-Associated Fibroblasts (CAFs) through a CD74/macrophage migration inhibitory factor (MIF) pattern, and further differentiated into TGF-ß-enriched tissues. Furthermore, CXCL12+ TAMs recruited PD-L1+ Bregs via the CXCL12/CXCR4 axis, and CXCR4 expression was significantly positively correlated to PD-L1 expression in PD-L1+ Bregs. At last, we confirmed the communications among CAFs, Macrophages and B cells and their tumor-promoting effects by using an orthotopic mouse model of HCC. Immunosuppressive HCC TME involving cell-to-cell communications comprised MIF-secreting CAFs, CXCL12-secreting TAMs, and PD-L1-producing Bregs, and their regulation could be promising therapeutic targets in future immunotherapy for human HCC.

Insights into cryptic speciation of quillworts in China.

Cryptic species are commonly misidentified because of high morphological similarities to other species. One group of plants that may harbor large numbers of cryptic species is the quillworts (Isoëtes spp.), an ancient aquatic plant lineage. Although over 350 species of Isoëtes have been reported globally, only ten species have been recorded in China. The aim of this study is to better understand Isoëtes species diversity in China. For this purpose, we systematically explored the phylogeny and evolution of Isoëtes using complete chloroplast genome (plastome) data, spore morphology, chromosome number, genetic structure, and haplotypes of almost all Chinese Isoëtes populations. We identified three ploidy levels of Isoëtes in China-diploid (2n = 22), tetraploid (2n = 44), and hexaploid (2n = 66). We also found four megaspore and microspore ornamentation types in diploids, six in tetraploids, and three in hexaploids. Phylogenetic analyses confirmed that I. hypsophila as the ancestral group of the genus and revealed that Isoëtes diploids, tetraploids, and hexaploids do not form monophyletic clades. Most individual species possess a single genetic structure; however, several samples have conflicting positions on the phylogenetic tree based on SNPs and the tree based on plastome data. All 36 samples shared 22 haplotypes. Divergence time analysis showed that I. hypsophila diverged in the early Eocene (∼48.05 Ma), and most other Isoëtes species diverged 3-20 Ma. Additionally, different species of Isoëtes were found to inhabit different water systems and environments along the Yangtze River. These findings provide new insights into the relationships among Isoëtes species in China, where highly similar morphologic populations may harbor many cryptic species.

Loss of neurodevelopmental-associated miR-592 impairs neurogenesis and causes social interaction deficits.

microRNA-592 (miR-592) has been linked to neurogenesis, but the influence of miR-592 knockout in vivo remains unknown. Here, we report that miR-592 knockout represses IPC-to-mature neuron transition, impairs motor coordination and reduces social interaction. Combining the RNA-seq and tandem mass tagging-based quantitative proteomics analysis (TMT protein quantification) and luciferase reporter assays, we identified MeCP2 as the direct targetgene of miR-592 in the mouse cortex. In Tg(MECP2) mice, lipofection of miR-592 efficiently reduced MECP2 expression in the brains of Tg(MECP2) mice at E14.5. Furthermore, treatment with miR-592 partially ameliorated the autism-like phenotypes observed in adult Tg(MECP2) mice. The findings demonstrate that miR-592 might play a novel role in treating the neurodevelopmental-associated disorder.

Combined topical and systemic administration with human adipose-derived mesenchymal stem cells (hADSC) and hADSC-derived exosomes markedly promoted cutaneous wound healing and regeneration.

BACKGROUND: Cutaneous wound healing and regeneration have become a recognized health challenge in the world, which causes severe damage to the mental and physical health of patients. Human adipose-derived mesenchymal stem cells (hADSC) play an essential role in wound healing via their paracrine function. Exosomes secreted by hADSC may contribute to this progress. In this study, we investigated the potential clinical application roles of hADSC and hADSC-derived exosomes (hADSC-Exo) in cutaneous wound healing. METHODS: hADSC-Exo was isolated from human hADSC by ultracentrifugation. Mice were subjected to a full-thickness skin biopsy experiment and treated with either control vehicle or hADSC or hADSC-Exo by smearing administration (sm) or subcutaneous administration (sc) or intravenous administration (iv). The efficacy of hADSC and hADSC-Exo on wound healing was evaluated by measuring wound closure rates, histological analysis. RESULTS: Combined application of local hADSC-Exo smearing and hADSC/hADSC-Exo intravenous administration offered the additional benefit of promoting wound healing, accelerating re-epithelialization, reducing scar widths, and enhancing angiogenesis and collagen synthesis. Either topical application of hADSC-Exo or systemic administration with hADSC/hADSC-Exo appeared more effective in stimulating cell proliferation, inhibiting cell apoptosis and inflammation, and promoting skin elasticity and barrier integrity, with increased genes expression of PCNA, VEGF, collagen III, Filaggrin, Loricrin, and AQP3, with decreased genes expression of TNF-alpha. CONCLUSION: Our findings suggest that the combined administration of hADSC/hADSC-Exo can facilitate cutaneous wound healing and reduce scar formation. These data provide the first evidence for the feasibility of smearing of hADSC-Exo as a cell-free therapy in treating cutaneous wounds, and the potential clinical value of combined administration of hADSC/hADSC-Exo.

Chimeric-antigen receptor T (CAR-T) cell therapy for solid tumors: challenges and opportunities.

Chimeric antigen receptor (CAR)-engineered T cells (CAR-T cells) have been shown to have unprecedented efficacy in B cell malignancies, most notably in B cell acute lymphoblastic leukemia (B-ALL) with up to a 90% complete remission rate using anti-CD19 CAR-T cells. However, CAR T-cell therapy for solid tumors currently is faced with numerous challenges such as physical barriers, the immunosuppressive tumor microenvironment and the specificity and safety. The clinical results in solid tumors have been much less encouraging, with multiple cases of toxicity and a lack of therapeutic response. In this review, we will discuss the current stats and challenges of CAR-T cell therapy for solid tumors, and propose possibl e solutions and future perspectives.

Toll-like Receptor 4 Signaling Pathway in the Protective Effect of Pioglitazone on Experimental Immunoglobulin A Nephropathy.

BACKGROUND: In vitro experiments have revealed that toll-like receptor 4 (TLR4) pathway is involved in the progression of immunoglobulin A nephropathy (IgAN) by induction of proinflammatory cytokines. Evidence showed that, in other disease models, peroxisome proliferator-activated receptor-γ (PPAR-γ) agonists have been shown to exert anti-inflammatory effects through suppression of the expression and activity of TLR4. However, the interaction between PPAR-γ and TLR4 in IgAN has not been fully studied both in vitro and in vivo. In this study, we explored whether TLR4 pathway attributed to the progression of IgAN in experimental rats. METHODS: Bovine gamma globulin was used to establish IgAN model. Fifty-four Lewis rats were randomly divided into six groups: ControlTAK242, IgANTAK242, toll-like receptor 4 inhibitor (TAK242) groups (rats were administrated with TLR4 inhibitor, TAK242) and ControlPio, IgANPio, Pio groups (rats were administrated with PPAR-γ agonist, pioglitazone). Urinary albumin-to-creatinine ratio (ACR), serum creatinine, and blood urea nitrogen were detected by automatic biochemical analyzer. Renal histopathological changes were observed after hematoxylin-eosin staining, and the IgA deposition in glomeruli was measured by immunofluorescence staining. Real-time polymerase chain reaction and Western blotting were used to detect TLR4 and interleukin-1 beta (IL-1ß) message ribonucleic acid (mRNA) and protein expression in renal tissues. Results were presented as mean ± standard deviation. Differences between groups were analyzed by one-way analysis of variance. RESULTS: Compared to normal rats, experimental rats showed higher ACR (4.45 ± 1.33 mg/mmol vs. 2.89 ± 0.96 mg/mmol, P < 0.05), obvious IgA deposition with mesangial hypercellularity, hyperplasia of mesangial matrix accompanied by increased serum IL-1ß (48.28 ± 13.49 pg/ml vs. 35.56 ± 7.41pg/ml, P < 0.05), and renal expression of IL-1ß and TLR4. The biochemical parameters and renal pathological injury were relieved in both TAK242 group and Pio group. The expressions of renal tissue TLR4, IL-1ß, and serum IL-1ß were decreased in rats treated with TAK242, and the expression of TLR4 mRNA and protein was significantly reduced in Pio group compared to IgANPiogroup (1.22 ± 0.28 vs. 1.72 ± 0.45, P < 0.01, and 0.12 ± 0.03 vs. 0.21 ± 0.05, P < 0.01). CONCLUSIONS: Our study proves that inflammation mediated by TLR4 signaling pathway is involved in the progression of IgAN in rat models. Moreover, pioglitazone can inhibit the expression of TLR4 in IgAN.