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Effect of solvents on the self-assembly of long chain alkylphosphonic acids on indium tin oxide surface - In situ studies on the adsorption kinetics and electron transfer process
摘要： The spontaneous self-assembly process of phosphonic acids (PAs) onto indium tin oxide (ITO) surface has been studied in this work. We have carried out in situ adsorption kinetics studies of phosphonic acids in ethanol as a solvent using electrochemical impedance spectroscopy (EIS). Further, the effect of different solvents like ethanol, water, toluene and hexane on the structural integrity of the alkylphosphonic acid (CH3 (CH2)n PO3H2, n = 15,17) thin films on ITO surface has been investigated by using [Fe(CN)6]3-/4- as a redox probe. From the study of formation kinetics, it is concluded that molecular self-assembly process follows two adsorption steps, a fast first step followed by a slower second step. The results of cyclic voltammetric (CV) and impedance measurements show that phosphonic acids form a highly impermeable surface film on ITO when polar solvents like ethanol and water are used.
关键词： self assembly,Adsorption Kinetics,microelectrode array,Contact Angle,Capacitance,ITO,Phosphonic acid
更新于2025-09-23 15:23:52
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Effect of dissolved natural organic matter on the photocatalytic micropollutant removal performance of TiO2 nanotube array
摘要： The TiO2 nanotube array (TNA) is a promising photocatalyst for removal of micropollutants from water, but better understanding on its applicability in complex water matrices is still desired. Therefore this study investigates the effect of dissolved natural organic matter (NOMs) on 4-chloro-2-methylphenoxyacetic acid (MCPA, a typical micropollutant found in many water bodies) removal performance of TNA. The present study shows that although in bulk liquid phase NOMs would undergo photosensitization that can contribute to MCPA removal, the overall effect of NOMs on MCPA removal is detrimental due to the interaction between NOMs and the TNA surface: the total removal of MCPA decreased from 94.3% to 62.0% and 61.8%, in the presence of only 5 mg/L SWR-NOM and UMR-NOM respectively. Acidic pH was found to be able to mitigate the detrimental effect of NOMs (the total removal of MCPA was only decreased from 94.5% to 83.3% and 88.8% under acidic pH, in the presence of 15 mg/L SWR-NOM and UMR-NOM respectively), and the photosensitization effect of NOMs was strengthened; while under alkaline pH conditions the detrimental effect of NOMs completely vanished (the total removal of MCPA increased from 45.7% to 55.7% and 60.5% in the presence of 15 mg/L SWR-NOM and UMR-NOM respectively). Two commonly present co-existing anions, i.e. phosphate and bicarbonate, also mitigate the detrimental effect of NOMs. With 15 mg/L SWR-NOM: the presence of 100 mg/L bicarbonate increased the total removal of MCPA from 49.1% to 65.1%; the presence of 100 mg/L phosphate increased the total removal of MCPA from 49.1% to 62.5%. With 15 mg/L SWR-NOM, the presence of 100 mg/L bicarbonate increased the total removal of MCPA from 45.2% to 56.1%; the presence of 100 mg/L phosphate increased the total removal of MCPA from 45.2% to 62.9%. The photocurrent measurement support that the presence of such anions greatly suppresses the h + scavenging effect of NOMs; while other anions, i.e. chloride, nitrate, sulfate, showed no notable effect.
关键词： Micropollutant,MCPA,TiO2 nanotube array,Photocatalysis,Natural organic matter
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE Asia-Pacific Conference on Antennas and Propagation (APCAP) - Auckland (2018.8.5-2018.8.8)] 2018 IEEE Asia-Pacific Conference on Antennas and Propagation (APCAP) - MIMO Antenna Array Decoupling Based on a Metamaterial Structure
摘要： A metamaterial decoupling structure is designed and used to enhance the isolations in the MIMO antenna array consisting of two patch antenna elements which operate at 5.3 GHz. The distance from edge to edge between the two microstrip patch antennas is 11 mm which is about 0.19λ corresponding to the center resonance frequency. The designed metamaterial structure constructed with three modified split-resonator rings is periodically set in the middle of the devised MIMO array so as to reduce the effect of the surface wave propagation between the two microstrip antennas. The simulation results obtained from the calculations show that the isolation is enhanced about 12.5 dB without sacrificing the bandwidth and good radiation pattern characteristics.
关键词： metamaterial,decoupling,MIMO antenna array
更新于2025-09-23 15:23:52
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[IEEE 2018 2nd International Conference on Telematics and Future Generation Networks (TAFGEN) - Malaysia (2018.7.24-2018.7.26)] 2018 2nd International Conference on Telematics and Future Generation Networks (TAFGEN) - Design of 28/38 GHz Dual-Band Triangular-Shaped Slot Microstrip Antenna Array for 5G Applications
摘要： Nowadays, evolving an advanced technology for the next generation of wireless cellular communication networks has put a great interest for researchers over the world. This aim is to accomplish the growing demand for advanced data rates. The fifth generation (5G) promises more advantages and benefits to the world. It will create an essential difference over 4G. The design of 5G antenna providing broad bandwidth is very important to ensure the performance of 5G networks. In this paper, microstrip antennas array of single, two, four and six elements dual-band (28/38GHz) for 5G applications are discussed. The proposed antennas are printed on 1.575 mm-thick Rogers Duroid 5880 substrate with dielectric constant of εr= 2.2 and loss tangent (tan δ) of 0.0009. They consist of a triangular shaped radiating patch fed by a 50 ? microstrip line. The antenna bandwidth is furthered by etching the triangular shaped slot on the ground plane. The highest gain is provided by the antenna with six elements array for both frequencies. The maximum gain of 7.47 dBi with return loss of -30.70 dB at 28 GHz and 12.1 dBi with return loss of -34.5 dB at 38 GHz are obtained.
关键词： array antenna,dual band antenna,5G antenna,microstrip antenna
更新于2025-09-23 15:23:52
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Pattern Reconfigurable Wideband Loop Antenna for Thorax Imaging
摘要： A unidirectional loop antenna that can achieve wideband pattern re-configurability from -40 to +40 degrees in azimuth plane is presented. The antenna is designed to fulfill the multi-slice (level) scanning requirements of electromagnetic imaging (EMI) systems for thorax imaging. To overcome the need for positioning of several antenna-arrays, and hence eliminate the mutual coupling related complications, a square-loop antenna with reconfigurable pattern is designed. To create a unidirectional radiation, the loop is loaded with capacitive gaps, which convert its radiation mechanism to that of two virtual dipole arrays with quadrature phase excitation. By utilizing this feature, the location of the gaps are varied on the loop's structure to form virtual dipole arrays in different directions, thus rotating the radiation pattern without physically moving the structure of the antenna. As a proof of concept, six gaps were created on the loop and each gap is loaded with a PIN diode to electronically switch between the positions of the designed gaps, thus enabling changing the radiation direction. The proposed antenna can achieve a compact size of 0.32λ×0.32λ×0.002λ (λ is the wavelength of the lowest resonance of the antenna) and a wide fractional bandwidth of 32% at 0.8-1.15 GHz, with a peak gain and front-to-back-ratio of 2.1 dBi and 8 dB, respectively. The antenna is successfully tested on a thorax imaging platform to detect small volume of water (5 mL) inside lungs as an emulation of early pulmonary edema.
关键词： unidirectional antenna,virtual dipole array,pattern reconfigurable antenna,loop antenna,Electromagnetic imaging,wideband antenna
更新于2025-09-23 15:23:52
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Kalman Filtering Technique for Rooftop-PV System under Abnormal Grid Conditions
摘要： This paper presents a robust extended complex Kalman Filter (RECKF) based control for multifunctional double stage grid-connected solar photovoltaic array (SPVA) system. The main contributions of presented paper, include: 1) real power generation from SPVA fulfils the requirement of the connected loads and it provides the surplus power to the distribution network, 2) it behaves as a distribution static compensator, which performs various functionalities such as grid currents balancing, harmonics mitigation, unity power factor operation, 3) it is capable to operate under polluted grid scenarios such as under voltage, over voltage and imbalanced grid voltages. The SPVA feed-forward term is incorporated in the control technique to enhance the dynamic response of the system. The real coded particle swarm optimization (RCPSO) based metaheuristic approach is used for optimal tuning of the DC link voltage PI (Proportional Integral) controller. Simulation results illustrate the effectiveness of presented control algorithm under variations in point of common coupling (PCC) voltage. Test results illustrate the behaviour of grid-connected SPVA system subjected to various perturbations such as under voltages, over voltages, distorted and imbalanced grid voltages etc. The THDs (Total Harmonic Distortions) of grid currents are achieved well within recommended limits.
关键词： Power quality,Renewable energy,Solar photovoltaic array,Harmonics,VSC,Optimization
更新于2025-09-23 15:23:52
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Grid Interactive Single Stage Solar Powered Water Pumping System Utilizing Improved Control Technique
摘要： This paper proposes a single stage grid interactive solar powered switched reluctance motor (SRM) driven water pumping system with an efficient control technique. The control of proposed system provides the proficient maximum power point technique (MPPT) tracking and motor drive control with bidirectional power flow between the photovoltaic (PV) array and single phase grid. It has harmonics components elimination, improved dynamic performance and a DC offset rejection capability compared to other control. A PV feed-forward term is also incorporated in developed control to enhance the dynamic performance of the system and to minimize the size of DC link capacitor with improved MPPT performance. The novel scheme of fundamental switching of SRM drive over its maximum operational time (when the grid is present) makes system efficient and reliable. An improved perturb and observe (P&O) based maximum power point tracking (MPPT) algorithm is used in this system to minimize the undesirable losses in a PV array specially under varying insolation levels. The proposed control is tested on a developed prototype and its suitability is authenticated through simulated and test results under various conditions.
关键词： MPPT,Bidirectional Power Flow,Water Pump,Switched Reluctance Motor,VSC,PV Array,Power Quality
更新于2025-09-23 15:23:52
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Piezoluminescent devices by designing array structures
摘要： Mechanoluminescence has attracted increasing attentions because it can convert the kinetic energy during human daily motions into light to be used in sensors and displays. However, its practical applications are still hindered by the weak brightness and limited color while under large forces. Herein, we developed novel piezoluminescent devices (PLDs) which could effectively emit visible light under low pressing forces through the stress-concentration and enhancing deformation on the basis of carefully-designed array structures. The emitting colors were also tunable by using bilayer luminescent film under different pressures. This work not only provides a new strategy to effectively harvest mechanical energy into light, but also presents a scalable, low-cost and color-tunable PLD which shows great potentials in various applications such as luminescent floors, shoes and stress-activated displays.
关键词： mechanoluminescence,color-tunable,piezoluminescent device,array structure
更新于2025-09-23 15:23:52
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Miniaturized electrochemiluminescent biochip prepared on gold nanoparticles-loaded mesoporous silica film for visual detection of hydrogen peroxide released from living cells
摘要： Au nanoparticles (NPs) has been widely used for the detection of intracellular H2O2 to enhance the electron transfer process. But AuNPs are easy to aggregate in the live cells environment. Herein we report a rapid, reliable and low-cost electrochemiluminescent (ECL) biochip integrated by AuNPs-loaded mesoporous silica film (MSF) to detect H2O2 released by macrophage cells. The MSF was employed as a template to load AuNPs within the nanochannels to avoid aggregation. H2O2 could be catalyzed by AuNPs to promote the ECL reaction of luminol molecules in solution. The ECL intensity was significantly enhanced, and the peak potential was negatively shifted by 400 mV due to the excellent electrocatalytic ability of AuNPs. The integrated biochip demonstrated good reproducibility, with a wide linear range of 0.1–200 μM and an LOD of 25.3 nM. The reliability was evaluated by applying for the assessment of antioxidant activity of resveratrol using RAW 264.7 macrophage model. The AuNPs-loaded MSF integrated biochip can be easily adapted to the development of improved devices in biosensing, lab-on-a-chip, and nanofluidic systems.
关键词： Gold nanoparticles,Biochip array,Electrochemiluminescence,Reactive oxygen species,Mesoporous silica
更新于2025-09-23 15:23:52
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Novel Phased Array-Fed Dual-Reflector Antenna with Different Orthogonal Cross-Section by Imaging Reflector Antenna and Ring-Focus Cassegrain Antenna
摘要： We propose a novel phased array-fed dual-re?ector antenna that reduces performance degradation caused by multiple re?ection. The marked feature of the proposed con?guration is that di?erent re?ector pro?les are employed for the two orthogonal directions. The re?ector pro?le in the beam-scanning section (vertical section) is set to an imaging re?ector con?guration, while the pro?le in the orthogonal non-beam-scanning section (horizontal section) is set to a ring-focus Cassegrain antenna con?guration. In order to compare the proposed antenna with the conventional antenna in which multiple re?ection was problematic, we designed a prototype antenna of the same size, and veri?ed the validity of the proposed antenna. The results of the veri?cation were that the gain in the designed central frequency increased by 0.4 dB, and the ripple of the gain frequency properties that was produced by multiple re?ection was decreased by 1.1 dB. These results demonstrated the validity of the proposed antenna.
关键词： Beam-Scanning Function,Imaging Re?ector Antenna,Ring-focus Cassegrain Antenna,Center-Fed Re?ector Antenna,Phased Array-fed Re?ector Antenna,Doubly Curved Re?ector
更新于2025-09-23 15:23:52