Polycomb CBX7 Directly Controls Trimethylation of Histone H3 at Lysine 9 at the p16 Locus

BACKGROUND: H3K9 trimethylation (H3K9me3) and binding of PcG repressor complex-1 (PRC1) may play crucial roles in the epigenetic silencing of the p16 gene. However, the mechanism of the initiation of this trimethylation is unknown. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we found that upregulating the expression of PRC1 component Cbx7 in gastric cancer cell lines MGC803 and BGC823 led to significantly suppress the expression of genes within the p16-Arf-p15 locus. H3K9me3 formation was observed at the p16 promoter and Regulatory Domain (RD). CBX7 and SUV39H2 binding to these regions were also detectable in the CBX7-stably upregulated cells. CBX7-SUV39H2 complexes were observed within nucleus in bimolecular fluorescence complementation assay (BiFC). Mutations of the chromodomain or deletion of Pc-box abolished the CBX7-binding and H3K9me3 formation, and thus partially repressed the function of CBX7. SiRNA-knockdown of Suv39h2 blocked the repressive effect of CBX7 on p16 transcription. Moreover, we found that expression of CBX7 in gastric carcinoma tissues with p16 methylation was significantly lower than that in their corresponding normal tissues, which showed a negative correlation with transcription of p16 in gastric mucosa. CONCLUSION/SIGNIFICANCE: These results demonstrated for the first time, to our knowledge, that CBX7 could initiate H3K9me3 formation at the p16 promoter

Entrainment performance enhancement of HVAC systems with active chilled beams

Heating, ventilation and air conditioning (HVAC) systems with active chilled beams (ACB) terminal units are attracting increasing attention in both theoretical research and practical application, due to their superior benefits compared with variable air volume (VAV) systems. In conventional VAV systems, a large volume of recirculation air is distributed through ductwork by big exhaust and supply fans. The energy consumed by these fans is enormous. As water has a much higher heat capacity compared with air, the ACB system utilizes water instead as the media of heat exchange, saving energy from delivering less volume of air. The volume of water transferring the same cooling is much smaller than air. Therefore, ACB systems are more energy efficient, by taking advantage of using less energy in distributing the chilled water directly to the air-conditioned space. Besides the energy saving benefits, ACB system can save the space above suspended ceilings. As most of the space is occupied by air supplying duct, the bottleneck for buildings with VAV system diminishing the space is to decrease the size of duct. As the ACB system requires less air supplying, it is an inherent character of ACB system to occupy less space above the ceiling, so that the floor-to floor height of a building can be decreased. Our research is dedicated how to enhance the energy efficiency performance of HVAC systems with space-friendly ACB terminal units. To achieve this, we make use of different tools to investigate the energy efficiency of ACB systems in many aspects, especially by confining the geometric factors of terminal unit. The energy efficiency of the whole system can thus be increased. In the meanwhile, we also suggest reduction of the height of terminal unit, so that the ACB system can show a greater advantage in term of space saving. By these means, the economic value of the ACB system, as well as the user acceptance can be increased. Accurate measurement of experimental data is the foundation of computations and the subsequent studies. An innovative method of acquiring entrainment ratio is proposed and validated through our experimental studies. With this method, the entrainment performance of a commercial terminal unit is tested by a series of experiments. The performance of the commercial terminal unit is also considered as a benchmark to compare and contrast. We build a numerical model of the terminal unit in computational fluid dynamics (CFD) software. The software can simulate the air flow pattern inside the terminal unit. By iterative computations, the velocity of every single point inside the terminal unit can be numerically solved. Compared with the experimental data, the model is verified to accord with the experimental data and is thus proved valid. After the model is established, we make numerous simulations and modification, and finally achieve a model that can largely increase the performance of the terminal units. It is found that by changing the geometry of the mixing chamber and lengthening the nozzle, the modified structure can increase entrainment ratio by 32% under the same working condition and primary air volume flow rate. The height of terminal unit is also diminished to fit more tight space. The results obtained prove that the entrainment ratio of a terminal unit, as well as the efficiency of the whole air conditioning system, can be effectively increased by proper modification on its geometry. The findings about the nozzle can also guide the adjustment of other geometric characters of the terminal unit.Doctor of Philosophy (EEE

An Intelligent Identification Approach Using VMD-CMDE and PSO-DBN for Bearing Faults

In order to improve the fault diagnosis accuracy of bearings, an intelligent fault diagnosis method based on Variational Mode Decomposition (VMD), Composite Multi-scale Dispersion Entropy (CMDE), and Deep Belief Network (DBN) with Particle Swarm Optimization (PSO) algorithm—namely VMD-CMDE-PSO-DBN—is proposed in this paper. The number of modal components decomposed by VMD is determined by the observation center frequency, reconstructed according to the kurtosis, and the composite multi-scale dispersion entropy of the reconstructed signal is calculated to form the training samples and test samples of pattern recognition. Considering that the artificial setting of DBN node parameters cannot achieve the best recognition rate, PSO is used to optimize the parameters of DBN model, and the optimized DBN model is used to identify faults. Through experimental comparison and analysis, we propose that the VMD-CMDE-PSO-DBN method has certain application value in intelligent fault diagnosis

Design and Motion Planning of a Metamorphic Flipping Robot

With the advantages of high flexibility, strong adaptability, etc., the legged robot can help humans to complete numerous complicated tasks. In this paper, a kind of reconfigurable legged robot with a flexible waist was proposed. Compared with the common robots with a rigid trunk, the proposed robot can twist its waist flexibly. Through analysis, it is found that the flexible waist can improve the trunk workspace, foot endpoints’ workspace and static stability margin of the robot, and further enhance the motion performance of the robot. Meanwhile, by imitating the creatures in nature, the motion gait planning of the robot was provided. Additionally, the proposed robot has excellent reconfigurable characteristics, and can flexibly transform among three forms to adapt to different working environments and accomplish different tasks. Further, after capsizing, the robot can complete the motion of turning over more easily. In this paper, the reconfiguration posture and the motion of turning over of the robot were planned in detail, and finally verified by ADAMS simulation

A Low-Energy Consumption Planning Method for Multi-Locomotion Wheel-Legged Mobile Robots

Mobile robots can replace humans to fulfill tasks in dangerous environments, which has been a research focus in recent years. This paper proposes a wheel-legged mobile robot with multi-locomotion and a low-energy consumption planning method. Different from the existing wheel-legged mobile robots, it can realize low-energy movement in different terrains with simple structures, and it can realize three modes: synchronous, tumbling, and curl–stretch. Then, based on the kinematics and dynamics model, a low-energy planning method is proposed, and low-energy motion planning is carried out for the three modes to obtain the low-energy driving law in each mode. A robot prototype is developed, and the experimental results show that the robot can move through the three modes with lower energy consumption in all three terrains. The planning method provides an effective reference for applying wheel-legged mobile robots

Chloride-Passivated Mg-Doped ZnO Nanoparticles for Improving Performance of Cadmium-Free, Quantum-Dot Light-Emitting Diodes

Colloidal ZnO nanoparticles (NPs) are widely used as an electron-transporting layer (ETL) in the solution-processed quantum-dot light-emitting diodes (QD-LEDs). However, the inherent drawbacks including surface defect sites and unbalanced charge injection prevent the device from realizing their further performance enhancement. In this work, a series of Mg doped ZnO (ZnO:Mg) and chloride-passivated ZnO (Cl@ZnO) NPs were synthesized by using a solution-precipitation strategy, and they exhibited tunable optical bandgaps and upward-shift of conduction-band maximum (CBM). Solution-processed QD-LEDs based on cadmium-free Cu-In-Zn-S/ZnS (CIZS/ZnS) nanocrystals (NCs) were fabricated by using ZnO:Mg and Cl@ZnO NPs as the ETLs, whose maximum peak external quantum efficiency (EQE) was nearly twice as high as that of QD-LEDs using ZnO NPs as the ETL (EQE = 1.54%). To take advantage of the benefits of ZnO:Mg and Cl@ZnO NPs, Cl@ZnO:Mg NPs were developed through the integration of Mg doping and Cl-passivation. Surprisingly, the cadmium-free QD-LEDs with the Cl@ZnO:Mg NPs as the ETL exhibited a maximum peak EQE of 3.72% and current efficiency of 11.08 cd A^–1, which could be enhanced to be 4.05% and 12.17 cd A^–1 by optimizing the Cl amount, respectively. The positive effects of the Mg doping and Cl-passivation on the cadmium-free QD-LEDs are primarily ascribed to the reduced electron injection barrier of ETL/the emitting layer interface and slower electron mobility, which can be verified by the ultraviolet photoelectron spectroscopy (UPS) measurements and current density–voltage characteristics of electron-only devices