Direct observation of ordered configurations of hydrogen adatoms on graphene

Ordered configurations of hydrogen adatoms on graphene have long been proposed, calculated and searched for. Here we report direct observation of several ordered configurations of H adatoms on graphene by scanning tunneling microscopy. On the top side of the graphene plane, H atoms in the configurations appear to stick to carbon atoms in the same sublattice. A gap larger than 0.6 eV in the local density of states of the configurations was revealed by scanning tunneling spectroscopy measurements. These findings can be well explained by density functional theory calculations based on double sided H configurations. In addition, factors that may influence H ordering are discussed

Quasi-1D graphene superlattices formed on high index surfaces

We report preparation of large area quasi-1D monolayer graphene superlattices on a prototypical high index surface Cu(410)-O and characterization by Raman spectroscopy, Auger electron spectroscopy (AES), low energy electron diffraction (LEED), scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). The periodically stepped substrate gives a 1D modulation to graphene, forming a superlattice of the same super-periodicity. Consequently the moire pattern is also quasi-1D, with a different periodicity. Scanning tunneling spectroscopy measurements revealed new Dirac points formed at the superlattice Brillouin zone boundary as predicted by theories.Comment: 4 figure

Real-time Monitoring for the Next Core-Collapse Supernova in JUNO

Core-collapse supernova (CCSN) is one of the most energetic astrophysical events in the Universe. The early and prompt detection of neutrinos before (pre-SN) and during the SN burst is a unique opportunity to realize the multi-messenger observation of the CCSN events. In this work, we describe the monitoring concept and present the sensitivity of the system to the pre-SN and SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is a 20 kton liquid scintillator detector under construction in South China. The real-time monitoring system is designed with both the prompt monitors on the electronic board and online monitors at the data acquisition stage, in order to ensure both the alert speed and alert coverage of progenitor stars. By assuming a false alert rate of 1 per year, this monitoring system can be sensitive to the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos up to about 370 (360) kpc for a progenitor mass of 30$M_{\odot}$ for the case of normal (inverted) mass ordering. The pointing ability of the CCSN is evaluated by using the accumulated event anisotropy of the inverse beta decay interactions from pre-SN or SN neutrinos, which, along with the early alert, can play important roles for the followup multi-messenger observations of the next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure

Transcriptional Regulation of Gene Expression by microRNAs as Endogenous Decoys of Transcription Factors

Background/Aims: MicroRNAs (miRNAs) are known to produce post-transcriptional repression of gene expression. In light of the ability of decoy oligodeocynucleotides (ODNs) to sequestrate transcription factors (TFs) and the similar double-stranded structure between decoy ODNs and miRNAs, we proposed that miRNAs might act as endogenous decoy molecules to produce transcriptional regulation of gene expression. Methods: Quantitative real-time RT-PCR analysis was used to measure the changes of miRNA and mRNA expression. Luciferase reporter gene activity assay was used to investigate the functional interaction between miRNAs and TFs. Electrophoresis mobility shift assay (EMSA) and modified chromatin immunoprecipitation assay (ChIP) were utilized to investigate the physical interactions between miRNAs and TFs. MTT cell viability assay and cellular DNA fragmentation ELISA were used to study apoptotic cell death. Results: We presented here that miRNAs could regulate, either negatively or positively, gene expression at the transcriptional level through its decoy-like actions and this mechanism operates under physiological conditions to produce cellular functions. We identified the putative cis-elements for transcriptional factors NF-κB and NFAT in the mature miR-939 and miR-376a, respectively. We experimentally established the ability of these miRNAs to physically bind their respective target TFs, using EMSA and ChIP methods. We then utilized the luciferase reporter gene assay to characterize the specific regulation of luciferase gene activities by miR-939/pre-miR-939:NF-κB or miR-376a/pre-miR-376a:NFAT interactions. Moreover, miR-939 and miR-376a produced transcriptional regulation of endogenous genes Bcl-xL and FasL/miR-26 that are the transcriptional targets for NF-kB and NFAT, respectively, but are not post-transcriptional targets for these two miRNAs. Finally, interference of these miRNAs with NF-κB and NFAT demonstrated clear phenotypes at the cellular level as manifested by the regulation of neuroblastoma cell death by miR-939 and miR-376a. Conclusion: Our study identified a novel non-canonical mechanism of miRNAs and suggests that when considering the cellular function of miRNAs the decoy-like mechanism for transcriptional regulation (activation or repression) should be taken into account

Selenium nanoparticles coated with pH responsive silk fibroin complex for fingolimod release and enhanced targeting in thyroid cancer

Cancer-targeted drug delivery systems based on nanoparticles (NPs) have been considered promising therapies. In this study, we developed a pH-responsive smart NPs drug delivery system using silk fibroin (SF), selenium nanoparticles (Se NPs), fingolimod (FTY720), and heptapeptide (T7). The prepared FTY720@T7-SF-Se NPs were spheres with an average diameter of 120 nm, which would contribute to the enhanced permeability and retention effects in tumour regions. The encapsulation efficiency (EE) of the FTY720@T7-SF-Se NPs was 71.95 ± 3.81%. The release of FTY720 from the nanocarriers was pH-dependent, and the release of FTY720 was accelerated in an acidic environment. Both in vitro and in vivo studies showed that FTY720@T7-SF-Se NPs had an enhanced cellular uptake selectivity and antitumor activity for thyroid cancer. The bio-distribution study in vivo further demonstrated that FTY720@T7-SF-Se NPs could effectively accumulate in the tumour region, thereby enhancing the ability to kill cancer cells in vivo. In addition, studies of histology and immunohistochemistry showed that FTY720@T7-SF-Se NPs had low toxicity to the major organs of tumour-bearing mice, indicating the prepared NPs has good biocompatibility in vivo. These results suggest that the tumour-targeted NPs delivery system (FTY720@T7-SF-Se NPs) has great potential as a new tool for thyroid cancer therapy