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FK506 suppresses hypoxia-induced inflammation and protects tight junction function via the CaN-NFATc1 signaling pathway in retinal microvascular epithelial cells
摘要： The present study aimed to identify whether FK506 suppresses hypoxia?induced inflammation and protects tight junction function via the calcineurin-nuclear factor of activated T?cells 1 (CaN?NFATc1) signaling pathway in mouse retinal microvascular endothelial cells (mRMECs). The mRMECs were treated with FK506 at different concentrations following the induction of hypoxia. Trans?epithelial electrical resistance (TEER) and cell permeability were examined to measure the integrity of the tight junctions. The concentrations of inflammatory cytokines were measured using reverse transcription-quantitative polymerase chain reaction analysis and enzyme?linked immunosorbent assays. The protein expression levels of zonula occludens-1 (ZO-1) and nuclear factor of activated T?cell 1 (NFATc1) were identified using immunofluorescent microscopy and western blot analysis. The TEER value was decreased following hypoxia, but increased following treatment with FK506 (1 and 10 μM) for 24 and 48 h. The protein expression of ZO?1 was also increased following FK506 treatment for 24 h at 1 and 10 μM. By contrast, following treatment with FK506 (1 and 10 μM) for 24 and 48 h, the elevated cell permeability in the hypoxia group was significantly downregulated. Similarly, the concentrations of inflammatory cytokines, including cyclooxygenase?2, inducible nitric oxide synthase, monocyte chemoattractant protein-1, interleukin?6, intercellular adhesion molecule?1 and vascular cell adhesion molecule?1, were downregulated following treatment with FK506 for 24 h at 1 and 10 μM. Following treatment with FK506, the level of total NFATc1 was downregulated and the level of phosphorylated NFATc1 was upregulated. Taken together, FK506 suppressed injury to the tight junctions and downregulated the expression of inflammatory cytokines in hypoxia?induced mRMECs via the CaN?NFATc1 signaling pathway. This suggests a potentially effective therapy for hypoxia?induced retinal microangiopathy.
关键词： inflammation,hypoxia,tight junction,calcineurin?nuclear factor of activated T?cells 1 signaling pathway,FK506
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC) - Kota Kinabalu, Malaysia (2018.10.7-2018.10.10)] 2018 IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC) - Transformer-less Single Phase H2D4 Inverter with Voltage Controller for Grid-tied PV System
摘要： Nowadays the transformer-less photovoltaic (PV) grid connected inverter is more popular because of its higher efficiency, compact size and lower cost. The issue of leakage current is a technical challenge, which needs to be controlled carefully. Moreover, many inverter topologies have been proposed to proficient the inverter to control the reactive power to a certain point in order to maintain the power factor (PF) close to one. In case of solar PV system, voltage fluctuation and synchronization with the utility grid is the challenging issue. Therefore, in this paper a new transformer-less inverter is proposed consisting of four diodes and two IGBT switches called H2D4 topology. The proposed topology can overcome the issue of leakage current by maintaining the common mode (CM) voltage constant while maintain low total harmonic distortion (THD) and higher PF. Because of the minimum number of IGBT switches, the leakage current and the conduction loss decrease. Besides, the size of the system is also decreased. Additionally, voltage fluctuation and synchronization are controlled by a newly proposed voltage controlled closed loop system where duty ratio is controlled. The proposed topology and the existing neutral point clamped (NPC) and H6 topologies are simulated in MATLAB/Simulink software, to clarify the theoretical analysis. It is found that the voltage controller closed loop control system of H2D4 inverter topology more efficiently control the voltage fluctuation problems while maintaining a low current THD with higher efficiency and high PF as compared with the system without control topology.
关键词： Grid connection,voltage synchronization,utility grid,total harmonic distortion,transformer-less inverter,power factor,leakage current,reactive power
更新于2025-09-04 15:30:14
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[IEEE 2018 2nd International Conference on Trends in Electronics and Informatics (ICOEI) - Tirunelveli, India (2018.5.11-2018.5.12)] 2018 2nd International Conference on Trends in Electronics and Informatics (ICOEI) - Power Quality Analysis & Characterization of Different Types of Lamp Used for Domestic and Industrial Purpose
摘要： In past, the incandescent lamp (IL) which is resistive load is used. Its power factor is unity & current is harmonic free but it consumes more power & generate heat. Last few decades compact fluorescent lamp (CFL) is widely used as it has an advantage of less power consumption & longer life. Nowadays Light Emitting Diode (LED) is used and have less energy consumption as compared to others lamp. But it has very less power factor, even if CFL & LED have a less energy consumption. It has various disadvantages such as it produces harmonic current due to use of semiconductor based devices. As harmonic current passes through impedance, it causes voltage distortion & hence degrading the overall power quality. In this paper the focus is given to the measurement of various power quality parameters such as Total Power Consumption and Total Harmonic Distortion for Current (ITHD) and Voltage (VTHD), Power Factor, Harmonics. The fluke 435 Series II Power Quality Analyzer is used for analysing different lamps used for residential, commercial, industrial purpose. This distorted current is improved as well as harmonics can be reduced by using harmonic filter. But it involves additional cost & expenses. Power Quality can be improved by adding harmonic filter with circuitry in lamp. This can lead to the improvement in Power Quality of overall power system.
关键词： Power Quality,LED,IL,harmonic distortion,CFL,power factor,Power Quality Analyzer
更新于2025-09-04 15:30:14
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An Ultra-Low-Jitter 22.8-GHz Ring-LC-Hybrid Injection-Locked Clock Multiplier With a Multiplication Factor of 114
摘要： An ultra-low-jitter, ring-LC-hybrid injection-locked clock multiplier (ILCM) is presented to achieve a high multiplication factor of 114. The proposed hybrid ILCM cascades a ring-type voltage-controlled oscillator (VCO)-based ILCM and an LC-type VCO-based ILCM. Using a dual-purpose frequency calibrator (DPFC) that can continuously calibrate the frequency drifts of the two VCOs, concurrently, the proposed ILCM can maintain excellent jitter performance against process-voltage-temperature (PVT) variations. Since the DPFC eliminates the use of an additional calibrator and operates at a very low frequency, it can reduce the expenditures for silicon and power. The proposed ILCM was fabricated in a 65-nm CMOS process. The RMS jitter of the 22.8-GHz output, integrated from 1 kHz to 100 MHz, was 153 fs, and the DPFC restricted its variations due to variations in temperatures and supply voltages to less than 180 fs. The proposed ILCM achieved the power efficiency of 0.32 mW/GHz. The active area was 0.2 mm2. The total power consumption was 7.4 mW, but the DPFC consumed only 400 μW.
关键词： ring-VCO,LC-voltage-controlled oscillator (VCO),clock multiplier,hybrid,multiplication factor,phase noise,jitter,Calibrator,injection locked
更新于2025-09-04 15:30:14
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Determination of Degree of Damage on Building Roofs Due to Wind Disaster from Close Range Remote Sensing Images Using Texture Wavelet Analysis
摘要： In the current era of increasing natural disasters, especially wind disasters such as tropical cyclones, tornadoes, thunder storms etc., the need for a rapid damage assessment and mitigation action became inevitable. Detecting damages on a wider perspective using remote sensing images makes the damage investigation much faster. The current work introduces the technology of texture-wavelet analysis for detection of roof damages due to cyclones and tornadoes from close range remote sensing imageries. Degree of Damage (DoD) is quantified by calculating the percentage of damaged portion of the building roofs. A positive correlation factor ranging from 0.75 to 0.80 for remote imagery with respect to the visually measured data as well as field investigation data validates the accuracy of the method. Thus depending on severity measured from the percentage area of damage determined, emergency aid and medication can be prioritized thereby aiding disaster mitigation process.
关键词： Degree of Damage,Remote Sensing Images,Natural Disaster,Texture-Wavelet analysis,Correlation Factor
更新于2025-09-04 15:30:14
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Fracture behaviors of a piezoelectric-piezomagnetic sandwich structure under electromechanical loads: plane problem
摘要： The fracture behaviors of a piezoelectric-piezomagnetic sandwich structure with an eccentric internal crack subjected to two kinds of in-plane electromechanical loads have been studied in this paper. A singular integral equation with Cauchy kernel is obtained by means of Fourier transform and further solved by using Gauss-Chebyshev technique. Then the stress intensity factors are obtained and some numerical results are presented to show the e?ects of the material properties, structure geometries, electromechanical loads and the crack location on the stress intensity factors. The conclusions of the present paper may be useful for the design and fracture prediction of layered piezoelectric-piezomagnetic structures.
关键词： sandwich structure,stress intensity factor,plane strain problem,integral transformation,Piezoelectric-Piezomagnetic composite
更新于2025-09-04 15:30:14
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Experimental Measurement and Monte Carlo Simulation the Correction Factor for the Medium-Energy X-ray Free-air Ionization Chamber
摘要： A key comparison has been made between the air-kerma standards of the National Institute of Metrology (NIM), China, and other Asia Pacific Metrology Programme (APMP) members in the medium-energy X-ray. This paper reviews the primary standard Free-air ionization chamber correction factor experimental method and Monte Carlo simulation method in the NIM. The experimental method and the Monte Carlo simulation method are adopted to obtain the correction factor for the medium-energy X-ray primary standard free-air ionization chamber at 100 kV, 135 kV, 180 kV, 250 kV four CCRI reference qualities. The correction factor has already been submitted to the APMP as key comparison data and the results are in good agreement with those obtained in previous studies. This study shows that the experimental method and the EGSnrc simulation method are usually used in the measurement of the correction factor. In particular, the application of the simulation methods is more common.
关键词： Correction factor,Air-kerma,Experimental method,Free-air ionization chamber,Monte Carlo simulation
更新于2025-09-04 15:30:14
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[IEEE 2018 International Conference on Smart Grid and Clean Energy Technologies (ICSGCE) - Sg. Long, Cheras, Kajang, Malaysia (2018.5.29-2018.6.1)] 2018 International Conference on Smart Grid and Clean Energy Technologies (ICSGCE) - H2D4-Type Single Phase Transformer-Less Inverter with Reactive Power Control for Grid-tied PV System
摘要： Transformer-less inverter is popular for grid-tied photovoltaic (PV) system due to low cost, smaller size and higher efficiency. However, one of the technical challenges, which need to be handled carefully, is the issue of leakage current. Moreover, an inverter must be capable of controlling the reactive power to a certain extend to maintain the power factor (PF) close to unity. Therefore, many inverter topologies have been proposed. In this paper, a new four diodes and two IGBT switch based H2D4-type highly efficient transformer-less inverter is proposed that can handle the issue of leakage current maintaining low total harmonic distortion (THD) and higher PF where the common mode (CM) voltage is maintained constant. As a result, the leakage current deceases and the conduction loss as well as size of the system is decreased due to minimum number of IGBT switches. Furthermore, two control systems are proposed to control the reactive power with desire PF. The comparison among proposed H2D4 topology and conventional neutral point clamped (NPC) and H6 topology have been analyzed in this paper. To validate the accuracy of the theoretical analysis, the compared topologies are simulated in MATLAB/Simulink software. It is found that the PLL and PI closed loop control based H2D4 inverter topology controls the reactive power maintaining a low current THD with higher efficiency and high PF as compared to the system with only PI control based topology.
关键词： total harmonic distortion,leakage current,H2D4 topology,reactive power,transformer-less inverter,power factor,grid connected photovoltaic
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications (WiPDA) - Atlanta, GA, USA (2018.10.31-2018.11.2)] 2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications (WiPDA) - Thermally Triggered SiC MOSFET Aging Effect on Conducted EMI
摘要： In this paper, thermally triggered SiC MOSFET aging effect on SiC based boost PFC converter’s conducted EMI is investigated. Existing EMI evaluation and suppression studies are mostly based on power devices at healthy state. This study provides a comprehensive EMI evaluation at different state of health of SiC MOSFET used in continuous conduction mode (CCM) Boost PFC converter. For this purpose, SiC MOSFET samples are exposed to accelerated aging and the corresponding device degradations are triggered by thermal stresses. To study device characteristics at different state of health, devices under test (DUT) electrical parameters and switching transients are evaluated over aging to support SiC based AC/DC converter’s conducted EMI discussion. Respectively, device aging effect on differential mode (DM) noise and common mode (CM) noise changes are discussed in detail. An 800W single phase CCM Boost PFC prototype is built to evaluate both DM and CM noise in band B frequency range (150kHz~30MHz) with experimental testing results. According to the study, high frequency noise decrement is observed after SiC MOSFET is thermally aged.
关键词： thermal stress,power factor correction (PFC),Accelerated aging,SiC power MOSFET,EMI/EMC
更新于2025-09-04 15:30:14
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Protective effects of ciliary neurotrophic factor on the retinal ganglion cells by injure of hydrogen peroxide
摘要： ● AIM: To explore the effect of ciliary neurotrophic factor (CNTF) on retinal ganglion cell (RGC)-5 induced by hydrogen peroxide (H2O2). ● METHODS: After cell adherence, RGC-5 culture medium was changed to contain different concentrations of H2O2 from 50 to 150 μmol/L at four time points (0.5, 1, 1.5 and 2h) to select the concentration and time point for H2O2 induced model. Two different ways of interventions for injured RGC-5 cells respectively were CNTF as an addition in the culture medium or recombinant lentiviral plasmid carrying CNTF gene transfecting bone mesenchymal stem cells (BMSCs) for co-culture with RGC-5. ● RESULTS: Compared to the control group, H2O2 led to RGC-5 death closely associated with concentrations and action time of H2O2 and we chose 125 μmol/L and 2h to establish the H2O2-induced model. While CNTF inhibited the loss of RGC-5 cells obviously with a dose-dependent survival rate. Nevertheless two administration routes had different survival rate yet higher rate in recombinant lentiviral plasmid group but there were no statistically significant differences. ● CONCLUSION: Both the two administration routes of CNTF have effects on RGC-5 cells induced by H2O2. If their own advantages were combined, there may be a better administration route.
关键词： retinal ganglion cells,ciliary neurotrophic factor,neuroprotection,hydrogen peroxide,recombinant lentiviral vector
更新于2025-09-04 15:30:14