Photoluminescence from nanocrystalline graphite monofluoride

We synthesize and study the structural and optical properties of nanocrystalline graphene monofluoride and graphite monofluoride, which are carbon-based wide bandgap materials. Using laser excitations 2.41 - 5.08 eV, we identify six emission modes of graphite monofluoride, spanning the visible spectrum from red to violet. The energy and linewidth of the modes point to defect-induced midgap states as the source of the photoemission. We discuss possible candidates. Our findings open the window to electro-optical applications of graphene fluoride.Comment: 11 pages including supporting information, 2 figure

A Mott insulator continuously connected to iron pnictide superconductors

Iron-based superconductivity develops near an antiferromagnetic order and out of a bad metal normal state, which has been interpreted as originating from a proximate Mott transition. Whether an actual Mott insulator can be realized in the phase diagram of the iron pnictides remains an open question. Here we use transport, transmission electron microscopy, X-ray absorption spectroscopy, and neutron scattering to demonstrate that NaFe$_{1-x}$Cu$_x$As near $x\approx 0.5$ exhibits real space Fe and Cu ordering, and are antiferromagnetic insulators with the insulating behavior persisting above the N\'eel temperature, indicative of a Mott insulator. Upon decreasing $x$ from $0.5$, the antiferromagnetic ordered moment continuously decreases, yielding to superconductivity around $x=0.05$. Our discovery of a Mott insulating state in NaFe$_{1-x}$Cu$_x$As thus makes it the only known Fe-based material in which superconductivity can be smoothly connected to the Mott insulating state, highlighting the important role of electron correlations in the high-$T_{\rm c}$ superconductivity.Comment: in press, Nat. Commun., 4 figures, supplementary information available upon reques

The FOXK1-CCDC43 Axis Promotes the Invasion and Metastasis of Colorectal Cancer Cells

Background/Aims: The CCDC43 gene is conserved in human, rhesus monkey, mouse and zebrafish. Bioinformatics studies have demonstrated the abnormal expression of CCDC43 gene in colorectal cancer (CRC). However, the role and molecular mechanism of CCDC43 in CRC remain unknown. Methods: The functional role of CCDC43 and FOXK1 in epithelial-mesenchymal transition (EMT) was determined using immunohistochemistry, flow cytometry, western blot, EdU incorporation, luciferase, chromatin Immunoprecipitation (ChIP) and cell invasion assays. Results: The CCDC43 gene was overexpressed in human CRC. High expression of CCDC43 protein was associated with tumor progression and poor prognosis in patients with CRC. Moreover, the induction of EMT by CCDC43 occurred through TGF-β signaling. Furthermore, a positive correlation between the expression patterns of CCDC43 and FOXK1 was observed in CRC cells. Promoter assays demonstrated that FOXK1 directly bound and activated the human CCDC43 gene promoter. In addition, CCDC43 was necessary for FOXK1- mediated EMT and metastasis in vitro and vivo. Taken together, this work identified that CCDC43 promoted EMT and was a direct transcriptional target of FOXK1 in CRC cells. Conclusion: FOXK1-CCDC43 axis might be helpful to develop the drugs for the treatment of CRC

Hepatitis C Virus Sensitizes Host Cells to TRAIL-Induced Apoptosis by Up-Regulating DR4 and DR5 via a MEK1-Dependent Pathway

BACKGROUND: Hepatitis C virus (HCV) is the leading cause of liver fibrosis, cirrhosis and hepatocellular carcinoma. It is believed that continuous liver cell apoptosis contributes to HCV pathogenesis. Recent studies have shown that HCV infection can sensitize host cells to TNF-related apoptosis-inducing ligand (TRAIL) induced apoptosis, but the mechanism by which HCV regulates the TRAIL pathway remains unclear. METHODS AND RESULTS: Using a sub-genomic replicon and full length virus, JFH-1, we demonstrate that HCV can sensitize host cells to TRAIL-induced apoptosis by up-regulating two TRAIL receptors, death receptor 4 (DR4) and death receptor 5 (DR5). Furthermore, the HCV replicon enhanced transcription of DR5 via Sp1, and the HCV-mediated up-regulation of DR4 and DR5 required MEK1 activity. HCV infection also stimulated the activity of MEK1, and the inhibition of MEK1 activity or the knockdown of MEK1 increased the replication of HCV. CONCLUSIONS: Our studies demonstrate that HCV replication sensitizes host cells to TRAIL-induced apoptosis by up-regulating DR4 and DR5 via a MEK1 dependent pathway. These findings may help to further understand the pathogenesis of HCV infection and provide a therapeutic target

Dynamic parameters’ identification for the feeding system of computer numerical control machine tools stimulated by G-code

This study proposed a dynamic parameters’ identification method for the feeding system of computer numerical control machine tools based on internal sensor. A simplified control model and linear identification model of the feeding system were established, in which the input and output signals are from sensors embedded in computer numerical control machine tools, and the dynamic parameters of the feeding system, including the equivalent inertia, equivalent damping, worktable damping, and the overall stiffness of the mechanical system, were solved by the least square method. Using the high-order Taylor expansion, the nonlinear Stribeck friction model was linearized and the parameters of the Stribeck friction model were obtained by the same way. To verify the validity and effectiveness of the identification method, identification experiments, circular motion testing, and simulations were conducted. The results obtained were stable and suggested that inertia and damping identification experiments converged fast. Stiffness identification experiments showed some deviation from simulation due to the influences of geometric error and nonlinear of stiffness. However, the identification results were still of reference significance and the method is convenient, effective, and suited for industrial condition

Five-axis Flank Milling Tool Path Generation with Smooth Rotary Motions

AbstractThe smoothness tool path is essential in five-axis high speed machining. However, the smoothness of the tool orientation in the part coordinate system cannot assure the smooth motions of the rotary axes of a five-axis machine tool because the conversion of tool posture from the part coordinate system to the machine coordinate system is nonlinear. To generate a tool path with smooth rotary motions of the five-axis machine tool, the tool path in this paper is represented with three spline curves: the cutter location curve and the two trajectory curves of the rotary axes of the machine tool, so that the rotary axes’ motions can be simultaneously smoothed. For a flank milling tool path, the geometric deviations between the envelope surface of the tool movement and the design surface should be respected while smoothing the tool path. The point-to-surface distance is adopted to calculate the geometric deviations, and then a smoothness optimization model is developed to smooth the rotary axes’ motions using the weighted least squares method. A numerical example of five-axis flank milling of a S-shape surface is given to confirm the validity and efficiency of the proposed approach

Structural Design and Simulation of Pneumatic Conveying Line for a Paddy Side-Deep Fertilisation System

To improve the consistency of sectional gas velocities in different rows in the pneumatic conveying line for a paddy side-deep fertilisation system, a new airflow equaliser was designed based on the mechanism of gas flow in ventilation engineering. Subsequently, the effects of key structural parameters and a position parameter of the airflow equaliser on the consistency of sectional gas velocities in different rows were investigated using the method of single-factor tests in Fluent, which provided a reasonable range for the next orthogonal test (notch angle (A): 120–180°, extended length (B): 18–30 mm and distance between adjacent branches (C): 120–160 mm). Thereafter, the parameters were optimised through an orthogonal test, using the coefficient of variation of the consistency of the sectional gas velocities in different rows (CV) as an indicator and using Fluent software. The results revealed that the order of primary and secondary factors was evaluated as B > A × B > C > A, and when A, B and C were selected as 150°, 30 mm and 120 mm, respectively, the consistency of the sectional gas velocities in different rows could get a very effective result (CV = 7.07%). Finally, to validate the feasibility of simulations of the performance of the airflow equalisers and to practically evaluate the contribution of the optimised airflow equalisers to improve the consistency of the sectional gas velocities in different rows, a bench test for the line with the optimised airflow equalisers and a simulation test for the line without the optimised airflow equalisers were carried out and the results showed that the CV values were 9.53%, 20.69%, respectively. It concluded that the optimised airflow equalisers could significantly improve the consistency of the sectional gas velocities in different rows by comparing the CV in the three tests including the simulation test for the line with the optimised airflow equalisers. This research provides a good reference for optimising the pneumatic conveying line for a paddy side-deep fertilisation system

Catalytic NO Reduction by CO over Ca-Fe Oxides in the Presence of O-2 with Sintering Flue Gas Circulation

Flue gas circulation is an important method to reduce NOx emission in the iron ore sintering process. In flue gas circulation, NOx is eliminated mainly through the reduction reaction with C or CO, in which CaFe2O4 plays an important role as the catalyst. In this paper, CaFe2O4 was synthesized by the ceramic rout; and the catalytic performance was investigated. The experimental results show that the reduced calcium ferrite (RCF) was superior to unreduced samples in catalytic activity and oxygen tolerance. The results of density functional theory (DFT) calculation and characterization showed that the RCF was in an electron-deficient state, which led to its higher catalytic activity. The electron-deficient state is more conducive to the complexation between the sample and oxygen under an oxygen-containing atmosphere, improving the O-2 tolerance in the CO-NO reaction. The results suggest that decreasing the O-2 content in the circulating flue gas will enhance the reducing atmosphere in the sintering bed and facilitate the catalytic reaction between CO and NO, which is beneficial for NOx removal