We discuss the photoluminescence (PL) of semiconducting transition metal dichalcogenides on the basis of experiments and a microscopic theory. The latter connects ab initio calculations of the single-particle states and Coulomb matrix elements with a many-body description of optical emission spectra. For monolayer MoS2, we study the PL efficiency at the excitonic A and B transitions in terms of carrier populations in the band structure and provide a quantitative comparison to an (In)GaAs quantum well-structure. Suppression and enhancement of PL under biaxial strain is quantified in terms of changes in the local extrema of the conduction and valence bands. The large exciton binding energy in MoS2 enables two distinctly different excitation methods: above-band gap excitation and quasi-resonant excitation of excitonic resonances below the single-particle band gap. The latter case creates a nonequilibrium distribution of carriers predominantly in the K-valleys, which leads to strong emission from the A-exciton transition and a visible B-peak even if the band gap is indirect. For above-band gap excitation, we predict a strongly reduced emission intensity at comparable carrier densities and the absence of B-exciton emission. The results agree well with PL measurements performed on monolayer MoS2 at excitation wavelengths of 405 nm (above) and 532 nm (below the band gap).
Background Interferon-γ (IFN-γ) is a major driver of excessive immune response, leading to intestinal mucosal damage and contributing the pathogenesis of Crohn’s diseases (CD). In contrast to the inflammatory cells and immune system, IFN-γ-induced cellular responses has not been well documented in the intestinal epithelium. The intestinal epithelium consists of multiple cell types and patient-derived intestinal organoid model may be appropriate to evaluate the IFN-γ-induced epithelial cellular responses in patients with CD. Methods To evaluate the IFN-γ-mediated epithelial cellular responses, human small intestinal organoids (enteroids) derived from the controls (n=6) and patients with Crohn’s disease (CD, n=10) were constructed. We focused on the IFN-γ-induced cell death mechanism upregulated in CD enteroids and validated them in surgically resected small intestine in patients with active CD. Results As the concentration of IFN-γ increased in the culture medium, the organoid-forming efficiency decreased steadily, which did not differ between control and CD enteroids. The enteroid viability measured using MTT was estimated to be 83.10 pg/ml for EC50. In control and CD enteroids treated with 100 pg/ml IFN-γ, PANoptosis was the main inflammatory cell death mechanism. Bulk and single-cell RNA sequencing revealed that IFN-γ induced the expression of MHC class II-associated genes, co-inhibitory molecule CD274 (PD-L1), and IDO1 in control and CD enteroids, which may be associated with peripheral tolerance in the absence of exogenous antigens. Gene set enrichment analysis identified an up-regulated antigen processing and presentation pathway with increased expression of MHC class I molecules in IFN-γ-treated CD enteroids compared to IFN-γ-treated control enteroids (normalized enrichment score=2.13, p=0.002, q=0.005). IFN-γ-induced MHC class I pathway could result in T cell-mediated cytotoxicity in CD enteroids. The selective JAK1 inhibitor, upadacitinib, inhibited the IFN-γ-induced PANoptosis and T cell-mediated cytotoxicity in CD enteroids. The expression of HLA-A and B was higher in the inflamed small intestine in patients with CD than those in patients with ischemic enteritis. Conclusion IFN-γ promotes antigen processing and presentation pathway in the intestinal epithelium. In patients with CD, increased expression of MHC class I molecules may induce T cell-mediated cytotoxicity, which could contribute to the development of CD.
Introduction Degenerative spondylolisthesis (dSpl) is translation of the vertebral body in relation to adjacent levels, mainly attributed to degenerative changes of the intervertebral disc and facet joint complexes, and primarily occurs at L4-L5. Studies have suggested that more sagittal oriented facet joints at L4-L5 are associated with dSpl. However, the role of facet joint tropism (i.e., asymmetry between facet joint orientations) in L4-L5 dSpl remains inconclusive, in particular, in an Asian population and possibly attributed to nonstandardized definitions of tropism. As such, the following study addressed the role of facet joint tropism in relation to L4-L5 dSpl in the Asia Pacific region. Materials and Methods A multinational, multiethnic cross-sectional image-based study was performed in 34 institutions in the Asia Pacific region. Lateral standing radiographs and axial MRIs and/or CT scans were obtained for patients diagnosed with lumbar dSpl. Imaging assessment consisted of the following: magnitude of slip displacement, level of spondylolisthesis, and left/right L4-L5 facet joint angulations were noted on image assessment. Patients with single level dSpl were included. Patients were further stratified into those presenting with (Group A) or without (Group B) L4-L5 dSpl. Facet joint tropism was defined as 7 degrees difference (Grogan et al 1997) between left and right facet joints and also assessed on receiver operating characteristics (ROC) curve analysis to identify critical values for multivariate analysis. Gender, age, weight/height (body mass index [BMI]), and ethnicity were also noted. Results The study included 351 patients (36.9% males and 63.1% females) with a mean age of 61.8 years (range: 24-90 years). The mean BMI was 25.6 kg/m2 (range: 15.4-43.9 kg/m2). There were 267 patients (76.1%) in Group A and 84 individuals (23.9%) in Group B (control). Sex type (p = 0.295) and BMI (p = 0.227) did not significantly differ between groups, but elevated age was more pronounced with L4-L5 dSpl (p = 0.001). There was a statistically significant difference between right and left L4-L5 facet joint angulations between Group A (right mean: 57.5 degrees; left mean: 55.4 degrees) and Group B (right mean: 48.4 degrees; left mean: 46.5 degrees) (p < 0.001). Based on facet joint tropism of 7 degrees difference between facet angulations, there was no statistically significant difference between groups. ROC analysis identified high sensitivity and specificity of facet joint angulation difference of 15 degrees or greater associated with dSpl. Based on age-adjusted multivariate analysis, facet joint tropism with a critical value of 15 degrees or greater angulation difference noted an odds ratio of 2.34 (95% CI: 1.17-4.67; p = 0.016) associated with dSpl. Slippage was noted with increased facet joint tropism, but the effects could not be discerned. Conclusion Greater sagittal FJ orientation was associated with dSpl, as was joint tropism. A critical value of 15 degrees FJ angle difference produced a twofold increase...
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