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Surface plasmon resonance of naked gold nanoparticles for photodynamic inactivation of Escherichia coli
摘要： Although antimicrobial photothermal inactivation of naked gold nanostructures using powerful pulsed lasers has been previously studied, there are little reports about their photodynamic antimicrobial properties under the irradiation of low-power density continuous wave lasers. Therefore, this paper attempts to fill this gap. In this paper, we studied the effects of a 40-mW/cm2 continuous Nd:Yag laser at 532 nm and naked gold nanoparticles on inactivation of Escherichia coli ATCC25922. According to our results, 60 min illumination using the Nd:Yag laser caused a 0.15log reduction of the bacterial viability. Also, the employed gold nanoparticles with an average size of 15 nm were toxic to E. coli ATCC 25922 in the concentrations above 0.5 μg/ml. In addition, synergistic effects of 0.5 μg/ml gold nanoparticles and the light illumination led to a 2.43log reduction of the viability after a 60-min exposure and did not show any considerable temperature change on the media. The obtained results were justified based on the possible interaction mechanisms of low-power density laser lights and naked gold nanoparticles. The paper is proposed as a prelude for future research about localized inactivation of resistant pathogens with minimum side effects on neighbor tissues.
关键词： Photodynamic inactivation,Gold nanoparticles,Low-power density laser,Surface plasmon resonance
更新于2025-11-25 10:30:42
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Highly Efficient and Durable Piezoelectric Nanogenerator and Photo-Power Cell Based on CTAB-Modified-Montmorillonite Incorporated PVDF Film
摘要： Herein, we have successfully designed two eco-friendly, biocompatible and cost-effective devices i.e. a piezoelectric nanogenerator (PENG) and a self-charged photo-power cell (PPC) by developing a multifunctional CTAB modified montmorillonite (MMT) incorporated poly(vinylidene fluoride) (PVDF) thin film with large electroactive β crystallites and dielectric properties. Incorporation of CTAB modified MMT in PVDF leads to nucleation of piezoelectric β crystallite (F(β)) ~ 91% as well as the dielectric constant ~ 48 at 3 mass% doping of CTAB-MMT. The enrichment of the electroactive β phase crystallization and high dielectric constant pilot to a good piezoelectricity ( d33) ~ 62.5 pC/N at 50 Hz of the thin film. Our CTAB-MMT/PVDF based PENG (CMPENG) with superior piezoelectricity shows high output power generation with power density ~ 50.72 mW/cm3 under periodic finger impartation and having ability to charge up a 1μF capacitor up to 2.4 V within 14 seconds under gentle finger impartation. The CMPENG also have the potential to glow up commercially available 26 blue light-emitting diodes (LEDs) connected in series. The self-charged PPC has been designed with the thin film in association with MnO2-MWNT/PVP/H3PO4. Our PPC is able to generate supercilious output voltage ~ 1.38 V and short circuit current ~ 3.7 mA/cm2under light illumination with specific areal capacitance and energy storage efficiency ~ 1501 F/m2 and ~ 93% respectively. The realistic application of our PPC is investigated by lightening up 24 blue LEDs for 7 days with same intensity by charging the device once for 50 seconds.
关键词： MMT,PVDF,power density,piezoelectric,dielectric,energy
更新于2025-11-14 17:28:48
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Power spectral density-based nearinfrared sub-band detection for noninvasive blood glucose prediction in both <i>in-vitro</i> and <i>in-vivo</i> studies
摘要： Diabetes is a widespread and serious disease and noninvasive measurement has been in high demand. To address this problem, a power spectral density-based method was offered for determining glucose sensitive sub-bands in the nearinfrared (NIR) spectrum. The experiments were conducted using phantoms of different optical properties in-vitro conditions. The optical bands 1200–1300 nm and 2100–2200 nm were found feasible for measuring blood glucose. After that, a photoplethysmography (PPG)-based low cost and portable optical system was designed. It has six different NIR wavelength LEDs for illumination and an InGaAs photodiode for detection. Optical density values were calculated through the system and used as independent variables for multiple linear regression analysis. The results of blood glucose levels for 24 known healthy subjects showed that the optical system prediction was nearly 80% in the A zone and 20% in the B zone according to the Clarke Error Grid analysis. It was shown that a promising easy-use, continuous, and compact optical system had been designed.
关键词： Noninvasive,led,blood glucose,power density.,nearinfrared,photoplethysmography
更新于2025-09-23 15:23:52
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Estimation of Zero-Frequency Noise Power Density in Digital Imaging
摘要： Noise power spectrum (NPS) at zero frequency can efficiently represent noise properties of imaging systems. However, estimations of zero-frequency NPS are susceptible to distortion due to several factors leading to low-estimate precisions. In this letter, a high-precision estimate algorithm for zero-frequency NPS is proposed. The proposed estimate is a compensated sum of signal variances and covariances. The accuracy and precision of the proposed approach were first observed with synthetic data. A flat panel radiography detector based on CsI(Tl)-scintillator was then used to experimentally observe the improved estimate precision of the proposed algorithm. Experiment results showed that the estimation precision was improved to 14 times compared to that of the conventional method.
关键词： Radiography imaging,sample mean of periodograms,zero-frequency noise power density
更新于2025-09-23 15:22:29
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Nanoconfinement-Induced Giant Electrocaloric Effect in Ferroelectric Polymer Nanowire Array Integrated with Aluminum Oxide Membrane to Exhibit Record Cooling Power Density
摘要： The electrocaloric effect (ECE) offers a unique mechanism to realize environmentally friendly and highly efficient solid-state cooling that completely differs from the conventional vapor-compression refrigeration. Here a new class of hybrid films composed of ferroelectric polymer nanowire array and anodic aluminum oxide (AAO) membrane is reported, which displays pronounced ECE driven by relatively low electric fields. Under confinement and orientation of AAO channels on the crystallization of the polymer, the polymer nanowire array shows substantially enhanced ECE that is about three times that of the corresponding thin films. Simultaneously, the integrated AAO membrane forms thermally conducting channels for the polymer nanowires, enabling the efficient transfer of cooling energy and operation of the EC materials under high frequencies, which are unattainable based on the currently available EC structures. Consequently, the integrated polymer nanowire–AAO hybrid film exhibits the state-of-the-art cooling power density, outperforming the current ferroelectric polymers, ceramics, and composites. This work opens a new route for the development of scalable, high-performance EC materials for next-generation refrigeration.
关键词： electrocaloric effect,nanoconfinement,cooling power density,heat transfer,ferroelectric polymer
更新于2025-09-23 15:22:29
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[IEEE SoutheastCon 2018 - St. Petersburg, FL (2018.4.19-2018.4.22)] SoutheastCon 2018 - Evaluation of Reference Generation Algorithms for Dispatching Solar PV Power
摘要： This paper aims to develop a low-cost energy storage system by evaluating reference generation algorithms for dispatching solar power for 1 MW photovoltaic (PV) arrays. Based on battery state of charge (SOC), rule-based algorithms are developed to adjust the grid reference power for each one-hour dispatching period. In this paper, several rule-based algorithms are used to control the SOC of the battery that plays a significant role to design cost-effective energy storage system. The price comparison is made between two kinds of energy storage system (i) Battery only (ii) Battery+ Supercapacitor (SC), where a low pass filter is used to allocate power between battery and SC. The most economical energy storage system is developed through extensive simulations in MATLAB/Simulink environment. The results show that the hybrid energy storage system (HESS), combination of battery and SC, outperforms a battery-only operation.
关键词： intermittent solar energy,high power density,depth of discharge (DOD),state of charge (SOC),high energy density,hourly dispatching
更新于2025-09-23 15:21:01
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[IEEE SoutheastCon 2018 - St. Petersburg, FL, USA (2018.4.19-2018.4.22)] SoutheastCon 2018 - Evaluation of Reference Generation Algorithms for Dispatching Solar PV Power
摘要： This paper aims to develop a low-cost energy storage system by evaluating reference generation algorithms for dispatching solar power for 1 MW photovoltaic (PV) arrays. Based on battery state of charge (SOC), rule-based algorithms are developed to adjust the grid reference power for each one-hour dispatching period. In this paper, several rule-based algorithms are used to control the SOC of the battery that plays a significant role to design cost-effective energy storage system. The price comparison is made between two kinds of energy storage system (i) Battery only (ii) Battery+ Supercapacitor (SC), where a low pass filter is used to allocate power between battery and SC. The most economical energy storage system is developed through extensive simulations in MATLAB/Simulink environment. The results show that the hybrid energy storage system (HESS), combination of battery and SC, outperforms a battery-only operation.
关键词： intermittent solar energy,high power density,depth of discharge (DOD),state of charge (SOC),high energy density,hourly dispatching
更新于2025-09-23 15:21:01
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High Performance Silicon Carbide Power Packaging—Past Trends, Present Practices, and Future Directions
摘要： This paper presents a vision for the future of 3D packaging and integration of silicon carbide (SiC) power modules. Several major achievements and novel architectures in SiC modules from the past and present have been highlighted. Having considered these advancements, the major technology barriers preventing SiC power devices from performing to their fullest ability were identified. 3D wire bondless approaches adopted for enhancing the performance of silicon power modules were surveyed, and their merits were assessed to serve as a vision for the future of SiC power packaging. Current efforts pursuing 3D wire bondless SiC power modules were described, and the concept for a novel SiC power module was discussed.
关键词： wide bandgap,3D packaging,high power density,power electronics,wire bondless
更新于2025-09-23 15:21:01
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Performance evaluation and optimization of the cooling system of a hybrid thermionic-photovoltaic converter
摘要： Hybrid thermionic-photovoltaic (TIPV) converters are efficient and clean solutions for the direct conversion of thermal energy to electricity, taking advantage of both the photovoltaic and thermionic phenomena. An important hurdle for their efficient operation is the overheating of the PV cell integrated within the TIPV anode, due to partial conversion of the emitted electron and photon fluxes to thermal heat. This obstacle needs to be overcome with an efficient, yet practical, cooler. In this work, a copper plate heat spreader is experimentally tested for TIPV cathode temperatures up to 1450 °C, whilst its performance is also assessed using a validated CFD model for temperatures up to ~2000 °C. A multi-parametric analysis is conducted testing two coolants: i) a water/ethylene glycol mixture at various temperatures (?5–40 °C) and mass flow rates (0.05–0.4 kg·s?1), and, ii) cryogenic liquid nitrogen at a temperature of ?196 °C and mass flow rate of 0.074 kg·s?1. Numerical results reveal that with water/ethylene mixture the PV can withstand heat fluxes up to 360 W·cm?2, without its temperature exceeding 100 °C. For higher thermal fluxes (360–600 W·cm?2), cryogenic liquid nitrogen is found to prevent the PV overheating and, therefore, is an attractive coolant; however, it poses safety concerns due to its possible boiling. Finally, two additional cooling system designs are proposed, a heat sink with straight fins and another with copper pipes, which offer higher heat transfer areas, but are more difficult to manufacture, than the copper plate heat spreader.
关键词： Ultra-high power density,Copper plate heat spreader,Cooling system design optimization,Electronic device,Computational fluid dynamics (CFD)
更新于2025-09-23 15:21:01
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[IEEE 2018 XIII International Conference on Electrical Machines (ICEM) - Alexandroupoli, Greece (2018.9.3-2018.9.6)] 2018 XIII International Conference on Electrical Machines (ICEM) - Design of a GaN Based Integrated Modular Motor Drive
摘要： In this study, design procedure of an Integrated Modular Motor Drive (IMMD) is presented focusing on high power density. The design is based on a permanent magnet synchronous motor (PMSM) and GaN FETs. Fractional slot concentrated windings are used on the stator. Slot/pole combination and winding configuration is selected based on having low cogging torque and high winding factor. An extended motor drive inverter topology is proposed where 2-level voltage source inverters are connected both in series and parallel. Optimum selection of number of modules is discussed and power semiconductor devices are selected based on loss characterization. Optimum DC link capacitor bank is determined and the effect of interleaving is investigated. The performance of the motor is validated with ANSYS/Maxwell simulations. Motor drive performance is obtained with MATLAB/Simulink simulations. The efficiency of the motor drive is enhanced by 2% compared to a conventional motor drive. An overall system power density over 1 kW/lt has been achieved with the proposed series/parallel motor drive configuration having GaN FETs.
关键词： Permanent magnet synchronous motor,Modular motor,Power density,Gallium nitride,Integrated motor drive
更新于2025-09-23 15:21:01