The endothelial molecular pathway of a new ATP-sensitive potassium channel (KATP) opener natakalim was investigated in mesenteric arterioles of rats.
A DMT wire myograph was used to evaluate the ...vasorelaxation effects of natakalim. Ca2+ responses of endothelial cells induced by natakalim were measured by laser confocal fluorescence microscopy. NO assay kits and Western blotting were used.
The new KATP opener natakalim significantly produced endothelium-dependent arteriolar dilation and increased endothelial cell intracellular calcium concentration (Ca2+i) as well as NO release, which could be inhibited by SB366791 and capsazepine, the specific TRPV1 blockers. Additionally, down-regulation of endothelial TRPV1 by RNA interference inhibited the Ca2+ influx induced by natakalim.
These results suggest that endothelial KATP mediated natakalim-induced vasorelaxation through increasing Ca2+i and NO production. Activation of endothelial TRPV1 channels and subsequent Ca2+ entry, and NO release at least partly contribute to endothelium-dependent vasorelaxation induced by natakalim.
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In view of the problem that the complex structure of distribution network and the low measurement data cause the low accuracy of distribution network state estimation, a distribution network weighted ...least square state estimation method based on phase measurement unit and network topology partitions is proposed.Firstly, based on the analysis of the network connectivity and the equilibrium degree of each partition, the topology partition model of the distribution network is established, and the distribution network is divided into several sub-regions to reduce the Jakobi matrix scale. Secondly, the synchronous phase measurement device is introduced to enrich the state estimation measurement types, improve the accuracy of measurement, and simplify the Jakobi matrix in each sub-region.Finally, through the power distribution system of IEEE33, the validity of the proposed method is verified from the aspects of state estimation accuracy, calculation time and convergence. The results show that the proposed method combines the advantages of network topology partition and phasor measurement unit, and improves the accuracy of state estimation while reducing the time of state estimation.
With the advent of the network economy and the network society, the network will enter a ubiquitous and omnipresent situation. Economic, cultural, military and social life will strongly depend on the ...network, while network security issues have become a common concern of all countries in the world. DDOS attack is undoubtedly one of the greatest threats to network security and the defense against DDOS attack is very important. In this paper, the principle of DDOS attack is summarized from the defensive purpose. Then the attack prevention in software definition network is analyzed, and the source, intermediate network, victim and distributed defense strategies are elaborated.
The employment difficulty of college students has become a hot topic of public concern, and the research on the employment tendency of college students is a topic that needs to be discussed in depth ...in the academic circle at this stage. Faced with a large number of student employment information, big data technology can be used to quickly process it. Therefore, this article takes college students from a certain university as the research object and analyzes the employment tendency of college students based on machine learning. It is found that a total of 79.67% of college students tend to work in enterprises. The number of boys willing to work in the provincial capital and above cities, small and medium cities, rural areas and other areas accounted for 32.31 %, 16.24%, and 3.09%, respectively, while the number of girls willing to work was 23.67%, 19.41 % , and 5.28%, respectively. University students' expectations for employment the number of people willing to earn a monthly salary of 3500-5000 yuan is the largest. Based on these data, we will analyze the student's tendency towards employment unit, employment area, and employment salary.
Distribution network operation trend prediction is a key technology to analyze the network security operation status and potential hidden dangers of distribution side dynamically, how to accurately ...depict distribution network operation status and trend change is an important work to ensure the safe and stable operation of distribution network. In this paper, a trend prediction strategy for distribution network operation is proposed. First, fusion integration Ensemble Empirical Mode Decomposition (EEMD) and Variational Mode Decom (VMD) establish a secondary modal decomposition model of distribution network operating parameters, extract relatively stable subsequents and trend sequences, in order to reduce the impact of disordered components in high frequency sequences on predictive accuracy; Moth Flame Optimization (MFO) optimizes the LSTM parameters and uses the optimized Long-term Memory Networks (LSTM) to predict the subsethics of the operating parameters to further improve the accuracy of the distribution network operation trend prediction, and finally, the validity of the method proposed in this paper is verified in the actual power grid in a province of China. This method can accurately depict the changing trend of distribution network operation and perceive the security risks that distribution network may awareness.
As a power generation device, direct ammonia protonic ceramic fuel cells (NH3–PCFCs) also produce a significant amount waste heat, which not only results in energy wastage but also abnormal operation ...if the waste heat is not removed. To address these concerns and enhance generation electricity capacity, a novel waste heat recovery system based upon NH3-PCFC and alkali metal thermal electric converter (AMTEC) is first proposed, wherein the AMTEC converts the high-grade exhaust heat produced by the NH3-PCFC to extra electricity. Considering ammonia decomposition sluggish kinetics, various irreversible overpotential losses of NH3-PCFC as well as thermodynamic losses within the integrated system, the energetic/exergetic performance parameters evaluating the NH3-PCFC, AMTEC and the hybrid system are formulated. The general performance characteristics of the proposed system are revealed, along with a sensitive analysis conducted under specific operational conditions or structural parameters. Numerical calculation exhibited that the maximum attainable power density of the hybrid system has been promoted 20.5 % than that of stand-alone NH3-PCFC system. The multi-objective genetic algorithm is utilized to optimize the hybrid system performance for trade-off the power output and efficiency. Optimized results show the power density and corresponding efficiency of proposed system can respectively reach 6762.3 W m−2 and 49.8 % in the corresponding optimization conditions.
•A novel direct ammonia protonic ceramic fuel cell based hybrid system is proposed.•Energetic and exergetic performances of the hybrid system are evaluated.•Effects of several structural parameters and operation conditions are revealed.•Combined system gains a 20.5 % increase in maximum power density.•Multi-objective optimization is utilized to optimize hybrid system performance.
In this Letter, erbium (Er3+) and ytterbium (Yb3+) codoped perovskite Cs2Ag0.6Na0.4In0.9Bi0.1Cl6 microcrystal (MC) is synthesized and demonstrated systematically to the most prospective optical ...temperature sensing materials. A dual-mode thermometry based on fluorescence intensity ratio and fluorescence lifetime provides a self-reference and highly sensitive temperature measurement under dual wavelength excitation at a temperature from 300 to 470 K. Combined with the white-light emission derived from self-trapped excitons (STEs), the characteristic emission peak of Er3+ ions can be observed under 405 nm laser excitation. The fluorescence intensity ratio (FIR) between perovskite and Er3+ is used as temperature-dependent probe signal, of which maximum value for relative and absolute sensitivities reaches to 1.40% K–1 and 8.20 × 10–2 K–1. Moreover, Er3+ luminescence becomes stronger with the feeding Yb3+ increasing under 980 nm laser excitation. The energy transfer of Er3+ and Yb3+ is revealed by power-dependent photoluminescence (PL) spectroscopy, and the involved upconversion mechanism pertains to the two-photon excitation process. The results reveal that the Er3+/Yb3+ codoped lead-free double perovskite MC is a good candidate for a thermometric material for the novel dual-mode design.
The presence of a direct band gap and high carrier mobility in few-layer black phosphorus (BP) offers opportunities for using this material for infrared (IR) light detection. However, the poor air ...stability of BP and its large contact resistance with metals pose significant challenges to the fabrication of highly efficient IR photodetectors with long lifetimes. In this work, we demonstrate a graphene–BP heterostructure photodetector with ultrahigh responsivity and long-term stability at IR wavelengths. In our device architecture, the top layer of graphene functions not only as an encapsulation layer but also as a highly efficient transport layer. Under illumination, photoexcited electron–hole pairs generated in BP are separated and injected into graphene, significantly reducing the Schottky barrier between BP and the metal electrodes and leading to efficient photocurrent extraction. The graphene–BP heterostructure phototransistor exhibits a long-term photoresponse at near-infrared wavelength (1550 nm) with an ultrahigh photoresponsivity (up to 3.3 × 103 A W–1), a photoconductive gain (up to 1.13 × 109), and a rise time of about 4 ms. Considering the thickness-dependent band gap in BP, this material represents a powerful photodetection platform that is able to sustain high performance in the IR wavelength regime with potential applications in remote sensing, biological imaging, and environmental monitoring.
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