Understanding and controlling charge and energy flow in state-of-the-art semiconductor quantum wells has enabled high-efficiency optoelectronic devices. Two-dimensional (2D) Ruddlesden-Popper ...perovskites are solution-processed quantum wells wherein the band gap can be tuned by varying the perovskite-layer thickness, which modulates the effective electron-hole confinement. We report that, counterintuitive to classical quantum-confined systems where photogenerated electrons and holes are strongly bound by Coulomb interactions or excitons, the photophysics of thin films made of Ruddlesden-Popper perovskites with a thickness exceeding two perovskite-crystal units (>1.3 nanometers) is dominated by lower-energy states associated with the local intrinsic electronic structure of the edges of the perovskite layers. These states provide a direct pathway for dissociating excitons into longer-lived free carriers that substantially improve the performance of optoelectronic devices.
Ruddlesden-Popper halide perovskites are 2D solution-processed quantum wells with a general formula A
A'
M
X
, where optoelectronic properties can be tuned by varying the perovskite layer thickness ...(n-value), and have recently emerged as efficient semiconductors with technologically relevant stability. However, fundamental questions concerning the nature of optical resonances (excitons or free carriers) and the exciton reduced mass, and their scaling with quantum well thickness, which are critical for designing efficient optoelectronic devices, remain unresolved. Here, using optical spectroscopy and 60-Tesla magneto-absorption supported by modeling, we unambiguously demonstrate that the optical resonances arise from tightly bound excitons with both exciton reduced masses and binding energies decreasing, respectively, from 0.221 m
to 0.186 m
and from 470 meV to 125 meV with increasing thickness from n equals 1 to 5. Based on this study we propose a general scaling law to determine the binding energy of excitons in perovskite quantum wells of any layer thickness.
MicroRNAs (miRNAs) play important roles in tumorigenesis by regulating oncogenes and tumor-suppressor genes. In this study, miR-187 and miR-200a were found to be expressed at higher levels in ovarian ...cancers than in benign tumors. In patients with ovarian cancer, however, higher levels of miR-187 and miR-200a expression were paradoxically associated with better OS and recurrence-free survival. Further, multivariate analysis showed that miR-187 served as an independent prognostic factor for patients with ovarian cancer (n=176). Computational prediction and microarray results indicated that miR-187 directly targeted Disabled homolog-2 (Dab2), and luciferase reporter assays confirmed that the target site of miR-187 was located at the 3'-UTR of the Dab2 gene. Generally considered as a tumor-suppressor gene, Dab2 may actually promote tumor progression in advanced cancers through epithelial-to-mesenchymal transition (EMT). Ectopic expression of miR-187 in cancer cells promoted cell proliferation, but continued overexpression of miR-187 suppressed Dab2 and inhibited migration. Suppression of miR-187 upregulated Dab2, which, by inhibiting E-cadherin levels while stimulating vimentin and phospho-FAK levels, promoted EMT. Reduced ovarian cancer Dab2 histoscores correlated with high miR-187 levels and improved outcomes of patients. Collectively, these results demonstrate distinct dual roles of Dab2 in cell proliferation and tumor progression. In the initial steps of tumorigenesis, upregulated miR-187 suppresses Dab2, promoting cell proliferation. During the later stages, however, continued increased levels of miR-187 inhibits the Dab2-dependent EMT that is associated with tumor invasiveness, which is presumed to be the reason why cancers with high miR-187 levels were associated with better survivals.
Background: Mutations of the epidermal growth factor receptor (EGFR) gene in non-small-cell lung cancer (NSCLC) patients predict the patients who will respond to EGFR tyrosine kinase inhibitor (TKI) ...treatment. A recent study has suggested that 33% of NSCLC showed primary tumor/metastasis discordance of EGFR expression by immunohistochemistry analysis. We intended to find out whether the EGFR mutations of primary lung cancers are concordant to that of corresponding metastatic tumors. Materials and methods: We analyzed EGFR exons 18–21 from paired primary and metastatic tumors in 67 lung cancer patients who had not received TKI before tissues were sampled. Results: Using the direct sequencing method, 9 of 18 (50%) patients with EGFR mutation-positive primary lung tumors had lost the mutations in metastases. For 26 patients who were EGFR mutation positive in the metastatic tumors, 17 (65%) were negative in the primary tumors. We analyzed these paired tissues with discrepant EGFR mutations by the Scorpion Amplified Refractory Mutation System assay. Finally, the discordant rate reached 27% (18 of 67 cases). Conclusion: EGFR mutations in primary lung tumors do not always reflect the same situation in metastases. Analysis of EGFR mutations in the primary lung tumor would be inadequate for planning the use of TKI for advanced NSCLC.
Traffic emissions are a significant source of airborne particulate matter (PM) in ambient environments. These emissions contain an abundance of toxic metals and thus pose adverse effects on human ...health. Size-fractionated aerosol samples were collected from May to September 2013 by using micro-orifice uniform deposited impactors (MOUDIs). Sample collection was conducted simultaneously at the inlet and outlet sites of Hsuehshan Tunnel in northern Taiwan, which is the second-longest freeway tunnel (12.9 km) in Asia. This endeavor aims to characterize the chemical constituents and size distributions, as well as fingerprinting ratios of particulate metals emitted by vehicle fleets. A total of 36 metals in size-resolved aerosols were determined through inductively coupled plasma mass spectrometry. Three major groups – namely, tailpipe emissions (Zn, Pb, and V in fine mode), wear debris (Cu, Cd, Fe, Ga, Mn, Mo, Sb, and Sn), and resuspended dust (Ca, Mg, K, and Rb) – of airborne PM metals were categorized on the basis of the results of enrichment factor, correlation matrix, and principal component analysis. Size distributions of wear-originated metals resembled the pattern of crustal elements, which were predominated by super-micron particulates (PM1–10). By contrast, tailpipe exhaust elements such as Zn, Pb, and V were distributed mainly in submicron particles. By employing Cu as a tracer of wear abrasion, several inter-metal ratios – including Fe / Cu (14), Ba / Cu (1.05), Sb / Cu (0.16), Sn / Cu (0.10), and Ga / Cu (0.03) – served as fingerprints for wear debris. However, the data set collected in this work is useful for further studies on traffic emission inventory and human health effects of traffic-related PM.
The dispersive sweep of fast radio bursts (FRBs) has been used to probe the ionized baryon content of the intergalactic medium
, which is assumed to dominate the total extragalactic dispersion. ...Although the host-galaxy contributions to the dispersion measure appear to be small for most FRBs
, in at least one case there is evidence for an extreme magneto-ionic local environment
and a compact persistent radio source
. Here we report the detection and localization of the repeating FRB 20190520B, which is co-located with a compact, persistent radio source and associated with a dwarf host galaxy of high specific-star-formation rate at a redshift of 0.241 ± 0.001. The estimated host-galaxy dispersion measure of approximately Formula: see text parsecs per cubic centimetre, which is nearly an order of magnitude higher than the average of FRB host galaxies
, far exceeds the dispersion-measure contribution of the intergalactic medium. Caution is thus warranted in inferring redshifts for FRBs without accurate host-galaxy identifications.
Central nervous system (CNS) metastases are common in patients with non-small-cell lung cancer (NSCLC). Osimertinib has shown systemic efficacy in patients with CNS metastases, and early clinical ...evidence shows efficacy in the CNS. To evaluate osimertinib activity further, we present a pre-specified subgroup analysis of CNS response using pooled data from two phase II studies: AURA extension (NCT01802632) and AURA2 (NCT02094261).
Patients with T790M-positive advanced NSCLC, who had progressed following prior epidermal growth factor receptor-tyrosine kinase inhibitor treatment, received osimertinib 80mg od (n=411). Patients with stable, asymptomatic CNS metastases were eligible for enrolment; prior CNS treatment was allowed. Patients with≥1 measurable CNS lesion (per RECIST 1.1) on baseline brain scan by blinded independent central neuroradiology review (BICR) were included in the evaluable for CNS response set (cEFR). The primary outcome for this CNS analysis was CNS objective response rate (ORR) by BICR; secondary outcomes included CNS duration of response, disease control rate (DCR) and progression-free survival (PFS).
Of 128 patients with CNS metastases on baseline brain scans, 50 were included in the cEFR. Confirmed CNS ORR and DCR were 54% 27/50; 95% confidence interval (CI) 39–68 and 92% (46/50; 95% CI 81–98), respectively. CNS response was observed regardless of prior radiotherapy to the brain. Median CNS duration of response (22% maturity) was not reached (range, 1–15months); at 9months, 75% (95% CI 53–88) of patients were estimated to remain in response. Median follow-up for CNS PFS was 11months; median CNS PFS was not reached (95% CI, 7, not calculable). The safety profile observed in the cEFR was consistent with the overall patient population.
Osimertinib demonstrated clinically meaningful efficacy against CNS metastases, with a high DCR, encouraging ORR, and safety profile consistent with that reported previously.
NCT01802632; NCT02094261
Summary
Background
Hepatitis C virus (HCV) infection has been linked to an increased risk of insulin resistance and carotid atherosclerosis.
Aim
To investigate the association between HCV infection ...and stroke, and the effect of interferon‐based therapy (IBT) on stroke risk in chronic hepatitis C (CHC) patients.
Methods
We conducted a retrospective cohort study that followed up 3113 subjects with a newly detected HCV infection and 12 452 age‐ and gender‐matched subjects without HCV infection selected from a random sample of 106 beneficiaries from the Taiwan National Health Insurance Program up to 5 years. Use of IBT was defined as treatment with interferon alpha, pegylated interferon alpha‐2a or pegylated interferon alpha‐2b for at least 3 months. The hazard ratio (HR) for newly detected stroke was calculated for subjects with HCV compared to those without HCV, and for IBT‐treated HCV patients compared to non‐IBT‐treated HCV patients while adjusting for possible confounding factors.
Results
The overall person‐years of follow‐up were 8624.11 in patients with HCV, 54 533.69 in patients without HCV, 666.65 in IBT‐treated patients, and 7886.49 in nontreated patients. The multivariable‐adjusted hazard ratio (HR) for newly detected stroke was 1.23 for subjects with HCV compared to the age‐ and sex‐matched subjects without HCV (adjusted HR = 1.23, 95% CI = 1.06–1.42, P = 0.008). Moreover, use of IBT significantly reduced the risk of stroke in HCV patients (adjusted HR = 0.39, 95% CI = 0.16–0.95, P = 0.039) after adjusting for known prognostic factors.
Conclusions
Interferon‐based therapy may reduce the long‐term risk of stroke in patients with chronic HCV infection.
Schistosomiasis is one of the most prevalent parasitic diseases, affecting millions of people in developing countries. Amongst the human-infective species, Schistosoma mansoni is also the most ...commonly used in the laboratory and here we present the systematic improvement of its draft genome. We used Sanger capillary and deep-coverage Illumina sequencing from clonal worms to upgrade the highly fragmented draft 380 Mb genome to one with only 885 scaffolds and more than 81% of the bases organised into chromosomes. We have also used transcriptome sequencing (RNA-seq) from four time points in the parasite's life cycle to refine gene predictions and profile their expression. More than 45% of predicted genes have been extensively modified and the total number has been reduced from 11,807 to 10,852. Using the new version of the genome, we identified trans-splicing events occurring in at least 11% of genes and identified clear cases where it is used to resolve polycistronic transcripts. We have produced a high-resolution map of temporal changes in expression for 9,535 genes, covering an unprecedented dynamic range for this organism. All of these data have been consolidated into a searchable format within the GeneDB (www.genedb.org) and SchistoDB (www.schistodb.net) databases. With further transcriptional profiling and genome sequencing increasingly accessible, the upgraded genome will form a fundamental dataset to underpin further advances in schistosome research.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
ABSTRACT Hot dust-obscured galaxies (hot DOGs), selected from Wide-Field Infrared Survey Explorer's all-sky infrared survey, host some of the most powerful active galactic nuclei known and may ...represent an important stage in the evolution of galaxies. Most known hot DOGs are located at , due in part to a strong bias against identifying them at lower redshift related to the selection criteria. We present a new selection method that identifies 153 hot DOG candidates at , where they are significantly brighter and easier to study. We validate this approach by measuring a redshift z = 1.009 and finding a spectral energy distribution similar to that of higher-redshift hot DOGs for one of these objects, WISE J1036+0449 ( ). We find evidence of a broadened component in Mg ii, which would imply a black hole mass of and an Eddington ratio of . WISE J1036+0449 is the first hot DOG detected by the Nuclear Spectroscopic Telescope Array, and observations show that the source is heavily obscured, with a column density of . The source has an intrinsic 2-10 keV luminosity of , a value significantly lower than that expected from the mid-infrared/X-ray correlation. We also find that other hot DOGs observed by X-ray facilities show a similar deficiency of X-ray flux. We discuss the origin of the X-ray weakness and the absorption properties of hot DOGs. Hot DOGs at could be excellent laboratories to probe the characteristics of the accretion flow and of the X-ray emitting plasma at extreme values of the Eddington ratio.
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