33 research outputs found
Edge-pinning effect of graphene nanoflakes sliding atop graphene
Edge effect is one of the detrimental factors preventing superlubricity in
laminar solid lubricants. Separating the friction contribution from the edge
atom and inner atom is of paramount importance for rational design of ultralow
friction across scales in van der Waals heterostructures. To decouple these
contributions and provide the underlying microscopic origin at the atomistic
level, we considered two contrast models, namely, graphene nanoflakes with
dimerized and pristine edges sliding on graphene monolayer based on extensive
ab initio calculations. We found the edge contribution to friction is lattice
orientation dependence. In particular, edge pinning effect by dimerization is
obvious for misaligned contact but suppressed in aligned lattice orientation.
The former case providing local commensuration along edges is reminiscent of
Aubry's pinned phase and the contribution of per edge carbon atom to the
sliding potential energy corrugation is even 1.5 times more than that of an
atom in bilayer graphene under commensurate contact. Furthermore, we
demonstrated that the dimerized edges as high frictional pinning sites are
robust to strain engineering and even enhanced by fluorination. Both structural
and chemical modification in the tribological system constructed here offers
the atomic details to dissect the undesirable edge pinning effect in layered
materials which may give rise to the marked discrepancies in measured friction
parameters from the same superlubric sample or different samples with the same
size and identical preparation.Comment: 18 pages,6 figure
Bioactive organic/inorganic hybrids with improved mechanical performance
New sol-gel functionalized poly-ethylene glycol (PEGM)/SiO2-CaO hybrids were prepared with interpenetrating networks of silica and PEGM through the formation of Si-O-Si bonds. Bioactive and mechanical properties were investigated for a series of hybrids containing varying organic/inorganic ratios and PEG molecular weights. In contrast to the unmodified PEG/SiO2-CaO hybrids, which rapidly dissolved and crumbled, the epoxy modified hybrids exhibited good mechanical properties and bioactivity. The compressive strength and Young's modulus were greater for higher molecular weight PEGM hybrids (PEGM600 compared to PEGM300). Compressive strengths of 138 MPa and 81 MPa were found for the 50: 50 and 60: 40 organic/inorganic hybrid samples respectively, which are comparable with cortical bone. Young's modulus values of ∼800 MPa were obtained for the 50 : 50 and 60 : 40 organic/inorganic hybrids. Bioactivity tests were conducted by immersing the hybrids into simulated body fluid and observing the formation of apatite. Apatite formation was observed within 24 hours of immersion. PEGM600 hybrids showed enhanced apatite formation compared to PEGM300 hybrids. Increased apatite formation was observed with increasing organic/inorganic ratio. 70 : 30 and 60 : 40 hybrids exhibited the greatest apatite formation. All PEGM hybrids samples had good cell viability and proliferation. The 60 : 40 PEGM600 hybrids displayed the optimal combination of bioactivity and mechanical strength. The bioactivity of these hybrids, combined with the enhanced mechanical properties, demonstrate that these materials have significant potential for bone regeneration applications
Glucose-fueled Micromotors with Highly Efficient Visible Light Photocatalytic Propulsion
Synthetic micro/nanomotors fueled by glucose are highly desired for numerous practical applications because of the biocompatibility of their required fuel. However, currently all of the glucose-fueled micro/nanomotors are based on enzyme-catalytic-driven mechanisms, which usually suffer from strict operation conditions and weak propulsion characteristics that greatly limit their applications. Here, we report a highly efficient glucose-fueled cuprous oxide@N-doped carbon nanotube (Cu_2O@N-CNT) micromotor, which can be activated by environment-friendly visible-light photocatalysis. The speeds of such Cu_2O@N-CNT micromotors can reach up to 18.71 μm/s, which is comparable to conventional Pt-based catalytic Janus micromotors usually fueled by toxic H_2O_2 fuel. In addition, the velocities of such motors can be efficiently regulated by multiple approaches, such as adjusting the N-CNT content within the micromotors, glucose concentrations, or light intensities. Furthermore, the Cu_2O@N-CNT micromotors exhibit a highly controllable negative phototaxis behavior (moving away from light sources). Such motors with outstanding propulsion in biological environments and wireless, repeatable, and light-modulated three-dimensional motion control are extremely attractive for future practical applications
GRIK3 rs490647 is a Common Genetic Variant between Personality and Subjective Well-being in Chinese Han Population
Personality and subjective well-being (SWB) have been suggested to be strongly related in previous studies. This study was intended to confirm the relationship between personality and SWB and tried to seek out the genetic variants which underlie both personality and SWB. The subjects were 890 participants from Chinese Han population. We evaluated their personality using the Big Five Inventory (BFI) and used the Satisfaction With Life Scale (SWLS) to reflect their SWB. Five single nucleotide polymorphisms (SNPs) were selected from the literature (rs1426371, rs2164273, rs322931, rs3756290, rs490647) and genotyped for genetic association study. We found negative correlations between neuroticism and SWB. On the contrary, extraversion and agreeableness were positively associated with SWB. Three SNPs (rs2164273, rs3756290, rs490647) out of the five were found to connect with personality (extraversion, neuroticism, conscientiousness and openness to experience) and rs490647 variants of GRIK3 was also associated with SWB. Individuals carrying G allele at this site were predisposed to have lower risk to be neuroticism and greater chance to be extraverted, open and satisfied with their life. In summary, our study revealed that rs490647 might be a good candidate genetic variant for personality and SWB in Chinese Han population
Deficiency of VCP-Interacting Membrane Selenoprotein (VIMP) Leads to G1 Cell Cycle Arrest and Cell Death in MIN6 Insulinoma Cells
Background/Aims: VCP-interacting membrane selenoprotein (VIMP), an ER resident selenoprotein, is highly expressed in β-cells, however, the role of VIMP in β-cells has not been characterized. In this study, we studied the relationship between VIMP deficiency and β-cell survival in MIN6 insulinoma cells. Methods: To determine the role of VIMP in β-cells, lentiviral VIMP shRNAs were used to knock down (KD) expression of VIMP in MIN6 cells. Cell death was quantified by propidium iodide (PI) staining followed by flow cytometric analyses using a FACS Caliber and FlowJo software. Cell apoptosis and proliferation were determined by TUNEL assay and Ki67 staining, respectively. Cell cycle was analyzed after PI staining. Results: The results show that 1) VIMP suppression induces β-cell apoptosis, which is associated with a decrease in Bcl-xL, and the β-cell apoptosis induced by VIMP suppression can be inhibited by overexpression of Bcl-xL; 2) VIMP knockdown (KD) decreases cell proliferation and G1 cell cycle arrest by accumulating p27 and decreasing E2F1; 3) VIMP KD suppresses unfolded protein response (UPR) activation by regulating the IRE1α and PERK pathways; 4) VIMP KD increases insulin secretion. Conclusion: These results suggest that VIMP may function as a novel regulator to modulate β-cell survival, proliferation, cell cycle, UPR and insulin secretion in MIN6 cells
One Low-cost Quartz Lamp Radiation Aerodynamic Heating Simulation Experiment System with Control Law Flexible Adjustment Feature
The quartz lamp radiation aerodynamic heating simulation experiment system plays an important role on the structure strength heat experiment. In order to reduce its price and enhance flexibility on control law design of experiment system, a design method for low-cost quartz lamp radiation aerodynamic heating simulation experiment system with control law flexible adjustment feature is proposed. The hardware part is constructed by taking Digital Signal Processor (DSP) as an implementing agency controller. The feedback temperature after processed is computed by DSP. But the experiment process control value is computed by computer. The feedback temperature and experiment process control value data are transferred by serial communication model between DSP and computer. The experiment process relation data is saved by computer with EXCEL file, including the given target spectrum, the feedback temperature and the control value. The results of experiments on system identification, PID spectrum tracking, different zone control and the open loop control show the effectiveness of the proposed method
One Low-cost Quartz Lamp Radiation Aerodynamic Heating Simulation Experiment System with Control Law Flexible Adjustment Feature
The quartz lamp radiation aerodynamic heating simulation experiment system plays an important role on the structure strength heat experiment. In order to reduce its price and enhance flexibility on control law design of experiment system, a design method for low-cost quartz lamp radiation aerodynamic heating simulation experiment system with control law flexible adjustment feature is proposed. The hardware part is constructed by taking Digital Signal Processor (DSP) as an implementing agency controller. The feedback temperature after processed is computed by DSP. But the experiment process control value is computed by computer. The feedback temperature and experiment process control value data are transferred by serial communication model between DSP and computer. The experiment process relation data is saved by computer with EXCEL file, including the given target spectrum, the feedback temperature and the control value. The results of experiments on system identification, PID spectrum tracking, different zone control and the open loop control show the effectiveness of the proposed method
Influencing Factors and Realization Path of Power Decarbonization—Based on Panel Data Analysis of 30 Provinces in China from 2011 to 2019
2011–2019 was the critical period of the low-carbon transformation of the power industry, reflecting the deepening influence of market mechanisms. Decarbonization of the new power system is a systematic project that needs to strengthen the top-level design and overall planning. Therefore, the paper first evaluates the decarbonization of the existing power system and controls the grid architecture, power structure, energy utilization, supply chain, and trading market to further optimize the system by strengthening the basic theoretical research of the new power system, exploring the key elements of the low-carbon development of the power system, promoting the breakthrough of the key subjects, and formulating the new power system decarbonization path. In the international push for carbon neutrality goals, identifying key factors in the decarbonization of the power system is critical to achieving low-carbon development in the power sector. Combined with the characteristics and development trends of the power industry, the five dimensions of “Power generation decarbonization (SP)”, “Energy utilization efficiency (EU)”, “Supply chain decarbonization (SC)”, and “Power grid decarbonization (PG)”, and “the Trading system (TS)” are selected to construct an evaluation index system for the power decarbonization and identify the key factors. The Analytic Network Process (ANP) Method is used to calculate the index weight and measure the decarbonization level of the power industry in 30 provinces in China from 2011 to 2019. The evaluation results reveal that the overall decarbonization level of the power industry is on the rise and has stabilized after peaking in 2016. The regression results of the systematic GMM estimation show that “the intensity of cross-regional transmission”, “the degree of carbon market participation”, “technology innovation”, and “policy support” can significantly promote power decarbonization, and different regions have heterogeneity. Therefore, we propose to achieve technological innovation and upgrading in the eastern region, strengthen the construction of smart grids in the central region, optimize the power structure in the western region, and improve the market mechanism as a whole, to form a low-carbon development path for the power industry
An Adaptive Failure Detector Based on Quality of Service in Peer-to-Peer Networks
The failure detector is one of the fundamental components that maintain high availability of Peer-to-Peer (P2P) networks. Under different network conditions, the adaptive failure detector based on quality of service (QoS) can achieve the detection time and accuracy required by upper applications with lower detection overhead. In P2P systems, complexity of network and high churn lead to high message loss rate. To reduce the impact on detection accuracy, baseline detection strategy based on retransmission mechanism has been employed widely in many P2P applications; however, Chen’s classic adaptive model cannot describe this kind of detection strategy. In order to provide an efficient service of failure detection in P2P systems, this paper establishes a novel QoS evaluation model for the baseline detection strategy. The relationship between the detection period and the QoS is discussed and on this basis, an adaptive failure detector (B-AFD) is proposed, which can meet the quantitative QoS metrics under changing network environment. Meanwhile, it is observed from the experimental analysis that B-AFD achieves better detection accuracy and time with lower detection overhead compared to the traditional baseline strategy and the adaptive detectors based on Chen’s model. Moreover, B-AFD has better adaptability to P2P network