In this article, a novel electrochemical sensor based on pristine graphene (PG) is successfully constructed to detect ascorbic acid (AA), dopamine (DA), and uric acid (UA). The PG is obtained by ...liquid-phase exfoliation of graphite and characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. The sensor based on PG prepared by this method to realize simultaneous determination of AA, DA, and UA is firstly reported. The linear detection ranges for AA, DA, and UA are 9.00–2314μM, 5.00–710μM, and 6.00–1330μM, respectively, with detection limits of 6.45, 2.00, and 4.82μM. This PG based sensor exhibits excellent performance for detection of AA, DA, and UA, which is much better than those electrochemical sensors based on chemical converted graphene.
Hepatitis C virus (HCV) infection usually induces chronic hepatic inflammation, which favors the initiation and progression of hepatocellular carcinoma (HCC). Moreover, microRNA‐155 (miR‐155) plays ...an important role in regulating both inflammation and tumorigenesis. However, little is known about whether and how miR‐155 provides the link between inflammation and cancer. In this study we found that miR‐155 levels were markedly increased in patients infected with HCV. MiR‐155 transcription was regulated by nuclear factor kappa B (NF‐κB), and p300 increased NF‐κB‐dependent miR‐155 expression. The overexpression of miR‐155 significantly inhibited hepatocyte apoptosis and promoted cell proliferation, whereas miR‐155 inhibition induced G0/G1 arrest. Up‐regulated miR‐155 resulted in nuclear accumulation of β‐catenin and a concomitant increase in cyclin D1, c‐myc, and survivin. Gain‐of‐function and loss‐of‐function studies demonstrated that miR‐155 promoted hepatocyte proliferation and tumorigenesis by increasing Wnt signaling in vitro and in vivo, and DKK1 (Wnt pathway inhibitor) overexpression inhibited the biological role of miR‐155 in hepatocytes. Finally, adenomatous polyposis coli (APC), which negatively regulates Wnt signaling, was identified as the direct and functional target of miR‐155. Conclusion: HCV‐induced miR‐155 expression promotes hepatocyte proliferation and tumorigenesis by activating Wnt signaling. The present study provides a better understanding of the relationship between inflammation and tumorigenesis, and thus may be helpful in the development of effective diagnosis and treatment strategies against HCV‐HCC. (HEPATOLOGY 2012;56:1631–1640)
Robotic friction stir welding has become an important research direction in friction stir welding technology. However, the low stiffness of serial industrial robots leads to substantial, ...difficult-to-measure end-effector deviations under the welding forces during the friction stir welding process, impacting the welding quality. To more effectively measure the deviations in the end-effector, this study introduces a digital twin model based on the five-dimensional digital twin theory. The model obtains the current data of the robot and six-axis force sensor and calculates the real-time end deviations using the robot model. Based on this, a virtual welding model was realized by integrating the FEA model with the digital twin model using a co-simulation approach. This model achieves pre-process simulation by iteratively cycling through the simulated force from the FEA model and the end displacement from the robot model. The virtual welding model effectively predicts the welding outcomes with a mere 6.9% error in lateral deviation compared to actual welding, demonstrating its potential in optimizing welding parameters and enhancing accuracy and quality. Employing digital twin models to monitor, simulate, and optimize the welding process can reduce risks, save costs, and improve efficiency, providing new perspectives for optimizing robotic friction stir welding processes.
The effect of stationary shoulder friction stir welding (SSFSW) on temperature gradient and material flow was investigated to optimize the SSFSW process. A three-dimensional numerical model of heat ...generation and material flow was established by using computational fluid dynamics, and thermo-physical phenomena of SSFSWed Ti-6Al-4V were quantitatively analyzed in terms of heat generation, heat transfer, material flow and viscosity. The temperature gradient was more uniform in a narrow stir zone produced by the SSFSW process. The distribution of velocity was studied, and instantaneous velocity center of tool was divided into two different velocity regions to study the material flow. The simulation results were verified by experimental thermal cycles of calculated position of model, which was in accordance with the experimental results.
Graphene has attracted a high level of research interest because of its outstanding electronic transport properties and optical properties. Based on the Kubo formalism and the Maxwell equations, it's ...demonstrated that the optical conductivity of graphene can be controlled through the applied voltage. And we find that the graphene-oxide-silicon (GOS) based waveguide can be made into either the electro-absorptive or electron-refractive modulators. Using graphene as the active medium, we present a new electro-refractive Mach-Zender interferometer based on the GOS structure. This new GOS-based electron-refractive modulation mechanism can enable novel architectures for on-chip optical communications.
•Certain common organic salts are first used for liquid-phase exfoliation of graphene.•They exhibit efficient assistance for graphite exfoliation in some organic solvents.•Up to 123 times enhanced ...exfoliation efficiency is achieved in DMSO.•The organic salt-assisted exfoliation method is simple, efficient, safe and economical.
Certain ordinary organic salts, such as edetate disodium, sodium tartrate, potassium sodium tartrate and sodium citrate were found to have universal and efficient assistant effect for liquid-phase exfoliation of graphite in common organic solvents to produce pristine graphene. Up to 123 times enhanced exfoliation efficiency was observed when sodium citrate was introduced into an exfoliation system consisting of natural graphite powder and dimethyl sulfoxide. TEM, AFM, Raman spectroscopy, EDX, TGA, and FTIR analysis showed graphite was successfully exfoliated into single or few-layer graphene nanosheets which were free of defects and oxides. The method is simple, effective, safe and economical.
Al–Zn–Mg–Cu alloys are widely used in large-scale structural components of the aerospace industry, but research on wire and arc additive manufacturing (WAAM) of Al–Zn–Mg–Cu alloys is lacking. This ...research focused on grain refining of Al–Zn–Mg–Cu alloys by adding TiN particles during WAAM. The WAAM component was filled with equiaxed grains and the grain orientation became more random because the coarse columnar grains were eliminated. The average grain size was reduced from a value of 459 μm to a value of 104 μm. Heterogeneous nucleation by TiN particles was the main grain refining mechanism, and the TiN particles located along the grain boundaries also helped prevent grain growth. The horizontal and vertical elongations were increased by 160% and 98%, respectively, because of grain refinement; whereas the horizontal tensile strength was increased by 38.1%. The enhanced mechanical properties were mainly attributable to grain refinement and weakening of the texture strength.
Copper (II) phthalocyanines (CuPcs) have attracted growing interest as promising hole‐transporting materials (HTMs) in perovskite solar cells (PSCs) due to their low‐cost and excellent stability. ...However, the most efficient PSCs using CuPc‐based HTMs reported thus far still rely on hygroscopic p‐type dopants, which notoriously deteriorate device stability. Herein, two new CuPc derivatives are designed, namely CuPc‐Bu and CuPc‐OBu, by molecular engineering of the non‐peripheral substituents of the Pc rings, and applied as dopant‐free HTMs in PSCs. Remarkably, a small structural change from butyl groups to butoxy groups in the substituents of the Pc rings significantly influences the molecular ordering and effectively improves the hole mobility and solar cell performance. As a consequence, PSCs based on dopant‐free CuPc‐OBu as HTMs deliver an impressive power conversion efficiency (PCE) of up to 17.6% under one sun illumination, which is considerably higher than that of devices with CuPc‐Bu (14.3%). Moreover, PSCs containing dopant‐free CuPc‐OBu HTMs show a markedly improved ambient stability when stored without encapsulation under ambient conditions with a relative humidity of 85% compared to devices containing doped Spiro‐OMeTAD. This work thus provides a fundamental strategy for the future design of cost‐effective and stable HTMs for PSCs and other optoelectronic devices.
Two new copper (II) phthalocyanine (CuPc) derivatives, namely CuPc‐Bu and CuPc‐OBu, are designed by molecular engineering of the non‐peripheral substituents of the Pc rings, and are further explored as dopant‐free hole‐transporting materials (HTMs) in perovskite solar cells (PSCs). The PSCs based on pristine CuPc‐OBu as HTMs afford a maximum power conversion efficiency of 17.6%, which is considerably higher than that of the devices with CuPc‐Bu (14.3%).
Cluster heatmaps are widely used in biology and other fields to uncover clustering patterns in data matrices. Most cluster heatmap packages provide utility functions to divide the dendrograms at a ...certain level to obtain clusters, but it is often difficult to locate the appropriate cut in the dendrogram to obtain the clusters seen in the heatmap or computed by a statistical method. Multiple cuts are required if the clusters locate at different levels in the dendrogram.
We developed DendroX, a web app that provides interactive visualization of a dendrogram where users can divide the dendrogram at any level and in any number of clusters and pass the labels of the identified clusters for functional analysis. Helper functions are provided to extract linkage matrices from cluster heatmap objects in R or Python to serve as input to the app. A graphic user interface was also developed to help prepare input files for DendroX from data matrices stored in delimited text files. The app is scalable and has been tested on dendrograms with tens of thousands of leaf nodes. As a case study, we clustered the gene expression signatures of 297 bioactive chemical compounds in the LINCS L1000 dataset and visualized them in DendroX. Seventeen biologically meaningful clusters were identified based on the structure of the dendrogram and the expression patterns in the heatmap. We found that one of the clusters consisting of mostly naturally occurring compounds is not previously reported and has its members sharing broad anticancer, anti-inflammatory and antioxidant activities.
DendroX solves the problem of matching visually and computationally determined clusters in a cluster heatmap and helps users navigate among different parts of a dendrogram. The identification of a cluster of naturally occurring compounds with shared bioactivities implicates a convergence of biological effects through divergent mechanisms.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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