Optical characterizations of PMMA/metal oxide nanoparticles thin films: bandgap engineering using a novel derived model.

A novel optical model of the experimental transmission spectra of nanocomposite PVC-PS hybrid thin films doped with silica nanoparticles.

This article reports a solution-processed synthesis of copper oxide (CuxO) to be used as a potential photocathode for solar hydrogen production in the solar water-splitting system. CuxO thin films ...

Solution-Processed Synthesis of Copper Oxide (CuxO) Thin Films for Efficient Photocatalytic Solar Water Splitting

This paper develops an auxetic cantilever beam energy harvester (ACBEH) to enhance the harvesting power from ambient vibration sources. A finite element analysis was performed to verify the power increase mechanism of the ACBEH. The simulation model of the ACBEH comprises of three main components: support, tip mass, and cantilever beam with a re-entrant hexagonal auxetic structure in which a piezoelectric element bonded to top of the auxetic region by using a thin elastic layer of epoxy. The performance of the ACBEH was computationally investigated and compared with an equivalent conventional energy harvester with a plain cantilever beam where they are attached to a bridge stay cable. The simulation result shows that the ACBEH excited by a harmonic acceleration of 1 m/s2 at 3 Hz is able to produce electric power of 427.22 μW, which is 2.51 times that of the power produced by the equivalent plain cantilever beam energy harvester (170.17 μW). This paper opens up a great potential of using auxetic cantilever beam applications for different energy harvesting systems in Metamaterials, Acoustics, Civil, Electrical, Aerospace, Biomedical, and Mechanical Engineering.

Auxetic cantilever beam energy harvester

This work describes an environmental-friendly preparation of ZnO nanoparticles using aqueous oat extract. The advanced electrochemical and optical features of green synthesized ZnONPs displayed excellent antibacterial activity and exhibited an important role in pharmaceutical determinations. The formation of nanoscale ZnO was confirmed using various spectroscopic and microscopic investigations. The formed nanoparticles were found to be around 100 nm. The as-prepared ZnONPs were monitored for their antibacterial potential against different bacterial strains. The inhibition zones for ZnONPs were found as Escherichia coli (16 mm), Pseudomonas aeruginosa (17 mm), Staphylococcus aureus (12 mm) and Bacillus subtilis (11 mm) using a 30-µg mL−1 sample concentration. In addition, ZnONPs exhibited significant antioxidant effects, from 58 to 67%, with an average IC50 value of 0.88 ± 0.03 scavenging activity and from 53 to 71% (IC50 value of 0.73 ± 0.05) versus the scavenging free radicals DPPH and ABTS, respectively. The photocatalytic potential of ZnONPs for Rhodamine B dye degradation under UV irradiation was calculated. The photodegradation process was carried out as a function of time-dependent and complete degradation (nearly 98%), with color removal after 120 min. Conclusively, the synthesized ZnONPs using oat biomass might provide a great promise in the future for biomedical applications.

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Multifunctional Eco-Friendly Synthesis of ZnO Nanoparticles in Biomedical Applications

Hybrid material of poly-methyle-methacrylate (PMMA)-benzyl-dimethyl-ketal-azo dye methyl red (MR) thin film composites doped by various concentrations of ZnO NPs have been dip coated on glass substrates. The existence of azo dye (MR) in the composite was intentional to give the solution the desired pH level and to induce the cis ↔ trans cycles through illumination ↔ thermal relaxation. The optical and structural properties of the as-prepared thin films are investigated in relevance to ZnO NPs contents and the period of UV light illumination (short- and long-wavelength UV light). We found that the PMMA-BDK-MR doped by 1% ZnO NPs could be successfully used in optical data storage by implementing this composite in the WRITE/READ/ERASE cycle repeatedly. Specifically, it was found that the absorption band of the PMMA-BDK-MR doped by 1% ZnO NPs thin film lies between 350 and 600 nm upon illumination with 366 nm UV light for 10 s. Thermogravimetric analysis (TGA) was used to investigate the thermal stability of PMMA-BDK-MR/ZnO NPs. The TGA results are presented and interpreted. Furthermore, we investigated annealed poly-methyle-methacrylate-benzyl-dimethyl-ketal-methyl-red (PMMA-BDK-MR) doped by 1% ZnO NPs thin films. The trans–cis cycle has been repeated sequentially to confirm the hysteresis behavior for possible data READ/WRITE or ERASE memory applications.

Synthesis and characterization of ZnO NPs-doped PMMA-BDK-MR polymer-coated thin films with UV curing for optical data storage applications

Interest in energy harvesters has grown rapidly over the last decade. The cantilever shaped piezoelectric energy harvesting beam is one of the most employed designs, due to its simplicity and flexibility for further performance enhancement. The research effort in the MEMS Piezoelectric vibration energy harvester designed using three types of cantilever materials, Lithium Niobate (LiNbO3), Aluminum Nitride (AlN) and Zinc Oxide (ZnO) with different substrate materials: aluminum, steel and silicon using COMSOL Multiphysics package were designed and analyzed. Voltage, mechanical power and electrical power versus frequency for different cantilever materials and substrates were modeled and simulated using Finite element method (FEM). The resonant frequencies of the LiNbO3/Al, AlN/Al and ZnO/Al systems were found to be 187.5 Hz, 279.5 Hz and 173.5 Hz, respectively. We found that ZnO/Al system yields optimum voltage and electrical power values of 8.2 V and 2.8 mW, respectively. For ZnO cantilever on aluminum, steel and silicon substrates, we found the resonant frequencies to be 173.5 Hz, 170 Hz and 175 Hz, respectively. Interestingly, ZnO/steel yields optimal voltage and electrical power values of 9.83 V and 4.02 mW, respectively. Furthermore, all systems were studied at different differentiate frequencies. We found that voltage and electrical power have increased as the acceleration has increased.

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Design and Analysis of MEMS Based Aluminum Nitride (AlN), Lithium Niobate (LiNbO 3 ) and Zinc Oxide (ZnO) Cantilever with Different Substrate Materials for Piezoelectric Vibration Energy Harvesters Using COMSOL Multiphysics Software

In this paper, mathematical modeling and simulation of a MEMS-based clamped square-shape membrane for capacitive pressure sensors have been performed. Three types of membrane materials were investigated (i.e. Zinc Oxide (ZnO), Zinc Sulfide (ZnS) and Aluminum Nitride (AlN)). Various performance parameters such as capacitance changes, deflection, nonlinearity, the sensitivity of the membrane structure for different materials and film-thicknesses have been considered using the Finite Element Method (FEM) and analytically determined using the FORTRAN environment. The simulation model outperforms in terms of the effective capacitance value. The results show that the membrane deflection is linearly related to the applied pressure. The ZnS membrane provides a capacitance of 0.023 pico-Farad at 25 kPa with a 42.5% relative capacitance changes to reference capacitance. Additionally, the results show that for ZnO and AlN membranes the deflection with no thermal stress is higher than that with thermal stress. However, an opposite behavior for the ZnS membrane structure has been observed. The mechanical and capacitance sensitivities are affected by the membrane thickness as the capacitance changes are inversely proportional to the membrane thickness. Such results open possibilities to utilize various materials for pressure sensor applications by means of the capacitance-based detection technique.

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Modeling of a square-shape ZnO, ZnS and AlN membrane for mems capacitive pressure-sensor applications

The XY model has been used in a centered rectangular lattice structure consists of two sub-lattices of spin 1–1/2 with different ferromagnetic couplings on each lattice and anti-ferromagnetic interaction between the two sub-lattices. Utilizing the Monte Carlo simulation, we have studied the energy per site, the specific heat, the total magnetization, the initial susceptibility, and hysteresis effects. Our results revealed that existences of two peaks on the specific heat and a single loop historic behavior. The Binder cumulant and initial susceptibility both confirmed the existence of critical temperature where the system possesses a phase transition to paramagnetism. Such behaviors are monitoring by the different coupling constants adopted in this study.

Nermeen S. Daoud

Papers

Synthesis and characterization of ZnO NPs-doped PMMA-BDK-MR polymer-coated thin films with UV curing for optical data storage applications

Design and Analysis of MEMS Based Aluminum Nitride (AlN), Lithium Niobate (LiNbO 3 ) and Zinc Oxide (ZnO) Cantilever with Different Substrate Materials for Piezoelectric Vibration Energy Harvesters Using COMSOL Multiphysics Software

Modeling of a square-shape ZnO, ZnS and AlN membrane for mems capacitive pressure-sensor applications

The Magnetic Properties of a Centered Rectangular Lattice with Mixed Spins Using XY Model