48 research outputs found
Hepatic p53 is regulated by transcription factor FOXO1 and acutely controls glycogen homeostasis
The tumor suppressor p53 is involved in the adaptation of hepatic metabolism to nutrient availability. Acute deletion of p53 in the mouse liver affects hepatic glucose and triglyceride metabolism. However, long-term adaptations upon the loss of hepatic p53 and its transcriptional regulators are unknown. Here we show that short-term, but not chronic, liver-specific deletion of p53 in mice reduces liver glycogen levels, and we implicate the transcription factor forkhead box O1 protein (FOXO1) in the regulation of p53 and its target genes. We demonstrate that acute p53 deletion prevents glycogen accumulation upon refeeding, whereas a chronic loss of p53 associates with a compensational activation of the glycogen synthesis pathway. Moreover, we identify fasting-activated FOXO1 as a repressor of p53 transcription in hepatocytes. We show that this repression is relieved by inactivation of FOXO1 by insulin, which likely mediates the upregulation of p53 expression upon refeeding. Strikingly, we find that high-fat diet-induced insulin resistance with persistent FOXO1 activation not only blunted the regulation of p53 but also the induction of p53 target genes like p21 during fasting, indicating overlapping effects of both FOXO1 and p53 on target gene expression in a context-dependent manner. Thus, we conclude that p53 acutely controls glycogen storage in the liver and is linked to insulin signaling via FOXO1, which has important implications for our understanding of the hepatic adaptation to nutrient availability
The Modelling and Control of a Singular Biological Economic System in a Polluted Environment
Preparation of Ce- and La-Doped Li4Ti5O12 Nanosheets and Their Electrochemical Performance in Li Half Cell and Li4Ti5O12/LiFePO4 Full Cell Batteries
This work reports on the synthesis of rare earth-doped Li4Ti5O12 nanosheets with high electrochemical performance as anode material both in Li half and Li4Ti5O12/LiFePO4 full cell batteries. Through the combination of decreasing the particle size and doping by rare earth atoms (Ce and La), Ce and La doped Li4Ti5O12 nanosheets show the excellent electrochemical performance in terms of high specific capacity, good cycling stability and excellent rate performance in half cells. Notably, the Ce-doped Li4Ti5O12 shows good electrochemical performance as anode in a full cell which LiFePO4 was used as cathode. The superior electrochemical performance can be attributed to doping as well as the nanosized particle, which facilitates transportation of the lithium ion and electron transportation. This research shows that the rare earth doped Li4Ti5O12 nanosheets can be suitable as a high rate performance anode material in lithium-ion batteries
Simulation of Magnetorheological Plane Polishing Scratch Creation Process and Suppression Method
This study was conducted to simulate the causes of, and suppress, the scratch damage on the workpiece surface during magnetorheological surface polishing. The molecular dynamics method combined with polishing contact trajectory modeling was used to simulate the scratch damage formation process, and the scratch damage morphology model was established by analyzing the scratch damage distribution characteristics in the magnetorheological plane polishing process. The effect of different process parameters on the scratch damage characteristics was predicted by simulation, and orthogonal experiments were designed to explore the preferred polishing process parameters that could suppress the scratch damage formation. Finally, it was further verified that the formation of scratch damage can be effectively suppressed by controlling the workpiece speed, polishing disc speed, and magnetic field generator speed, and adjusting the magnetic field eccentricity distance under the premise of ensuring the surface roughness and flatness of the workpiece
Study on Rock-Electric Characteristics of Cracked Porous Rocks by the Novel Multifactor Conductivity Model
Simulation of Magnetorheological Plane Polishing Scratch Creation Process and Suppression Method
This study was conducted to simulate the causes of, and suppress, the scratch damage on the workpiece surface during magnetorheological surface polishing. The molecular dynamics method combined with polishing contact trajectory modeling was used to simulate the scratch damage formation process, and the scratch damage morphology model was established by analyzing the scratch damage distribution characteristics in the magnetorheological plane polishing process. The effect of different process parameters on the scratch damage characteristics was predicted by simulation, and orthogonal experiments were designed to explore the preferred polishing process parameters that could suppress the scratch damage formation. Finally, it was further verified that the formation of scratch damage can be effectively suppressed by controlling the workpiece speed, polishing disc speed, and magnetic field generator speed, and adjusting the magnetic field eccentricity distance under the premise of ensuring the surface roughness and flatness of the workpiece
Attitude-Oriented Stability Control with Adaptive Impedance Control for a Wheeled Robotic System on Rough Terrain
Base stability for a wheeled robot while driving over rough terrain is a challenging issue. This paper proposes a novel base-stability control framework, consisting of an AVIC (adaptive variable-impedance control), AVIC-based tracking controller, and a THV (terrain height variation) and AC (attitude control) AC-based controller to stabilize the base on rough terrain. The AVIC-based controller aims to track the desired trajectory of the robot base while suppressing lumped disturbance, including system uncertainties in the internal dynamics and unknown external disturbance. The THV-based controller is utilized as a feedforward controller to improve posture tracking performance in order to achieve a horizontal posture. The AC-based controller is employed to maintain the horizontal posture of the base. The effectiveness and robustness of the proposed controllers are validated by a series of numerical trials, and the results are evaluated
Perceptual Hashing Based Forensics Scheme for the Integrity Authentication of High Resolution Remote Sensing Image
High resolution remote sensing (HRRS) images are widely used in many sensitive fields, and their security should be protected thoroughly. Integrity authentication is one of their major security problems, while the traditional techniques cannot fully meet the requirements. In this paper, a perceptual hashing based forensics scheme is proposed for the integrity authentication of a HRRS image. The proposed scheme firstly partitions the HRRS image into grids and adaptively pretreats the grid cells according to the entropy. Secondly, the multi-scale edge features of the grid cells are extracted by the edge chains based on the adaptive strategy. Thirdly, principal component analysis (PCA) is applied on the extracted edge feature to get robust feature, which is then normalized and encrypted with secret key set by the user to receive the perceptual hash sequence. The integrity authentication procedure is achieved via the comparison between the recomputed perceptual hash sequence and the original one. Experimental results have shown that the proposed scheme has good robustness to normal content-preserving manipulations, has good sensitivity to detect local subtle and illegal tampering of the HRRS image, and has the ability to locate the tampering area
Investigating the time- and space- dependent mechanical, physical and chemical properties of aged polyethylene gas pipes using nanoindentation tests
Macroscopic tensile tests are conventionally used to obtain mechanical properties of aged polyethylene (PE) gas pipes, but cannot characterize the inhomogeneous aging behavior of the specimens caused by diffusion-limited oxidation (DLO). Nanoindentation test procedures have, therefore, been adopted to obtain time- and space-dependent mechanical properties of small-sized PE pipe samples, especially, creep properties directly from two types of the PE pipes in accelerated aging and natural conditions. The results indicate that the energy-based method to calculate the initial contact stiffness is not only suitable for cementitious materials and rocks, but also for PE materials. The combination of nanoindentation creep test and generalized Kelvin model can extract detailed parameters that are more representative of the differences in material deformation. The change of crystallinity with aging times probably leading to the difference of mechanical properties was revealed by physical and chemical properties obtained by the DSC and FITR technique. In addition, the correlation between nanoindentation results and structural information also indicates crystallinity plays a dominant role on mechanical performances of the PE pipe. This method using nanoindentation can significantly promote the accuracy of mechanical properties characterization and possess well fitness for PE pipes in accelerated aging conditions or in-service
A Machine Learning Study on Internal Force Characteristics of the Anti-Slide Pile Based on the DOFS-BOTDA Monitoring Technology
Long-term monitoring of constructed anti-slide piles can help in understanding the processes by which anti-slide piles are subjected to the thrust of landslides. This paper examined the landslide control project of Badong No. 3 High School. The internal force of an anti-slide pile subjected to long-term action of landslide thrust was studied by Distributed Optical Fiber Sensing (DOFS) technology. The BP neural network was used for model training on the monitored strain values and the calculated bending moment values. The results show the following: (1) The monitoring results of the sensor fibers reflect the actual situation more accurately than steel rebar meters do and can locate the position of the sliding zone more accurately. (2) The bending moments distributed along the anti-slide pile have staged characteristics under the long-term action of landslide thrust. Three stages can be summarized according to the development trend of the bending moment values. These three stages can be divided into two change periods of landslide thrust. (3) The model produced by the BP neural network training can predict the bending moment values. In this paper, the sensing fibers monitoring over a long time interval provides a basis for long-term performance analysis of anti-slide piles and stability evaluation of landslides. Using the BP neural network for training relevant data can provide directions for future engineering monitoring. More novel methods can be devised and utilized that will be both accurate and convenient