CNTs-added PMNT/PDMS flexible piezoelectric nanocomposite for energy harvesting application

The flexible piezoelectric nanocomposites based on lead magnesium niobate titanate [Pb(Mg1/3Nb2/3)0.65Ti0.35O3; PMNT] particles in polydimethylsiloxane (PDMS) matrix were fabricated and characterized. PMNT powders are synthesized using the columbite precursor method. PMNT/PDMS flexible nanocomposites are then prepared by spin casting technique, where a small amount of carbon nanotubes (CNTs) is added into the PMNT/PDMS composite to enhance cross-links between PMNT particles and PDMS matrix. The phase and microstructure of the nanocomposite are investigated by using X-ray diffraction and scanning electron microscope (SEM). The electromechanical behavior is evaluated by using an autonomous pneumatic actuator. The flexible composite, occupying approximately 300 mm2, is capable of generating an open-circuit voltage (Voc) of 2.83 ± 0.24 V and a short-circuit current (Isc) signal of 0.33 ± 0.01 µA across 10 Ω resistor under mechanical load of 300 N. The generated electrical charges are 29026 pC. The relative dielectric constant is measured at 10 kHz and found to be 6.76 ± 1.15. The piezoelectric PMNT/PDMS composite can potentially be used in a variety of applications such as wearable sensors, actuators, and energy harvesting for converting kinetic energy into useful electrical energy

Production of biodiesel over waste seashell-derived active and stable extrudate catalysts in a fixed-bed reactor

In this work, waste seashell (Meretrix meretrix) was used as a renewable calcium source to prepare a series of heterogeneous base catalysts for production of biodiesel, a mixture of fatty acid methyl esters (FAME), via transesterification of palm oil with methanol in a continuous-flow fixed-bed reactor. To avoid a severe pressure drop in the reactor column, the catalysts were prepared via the dissolution–precipitation method in the presence of zinc nitrate and alumina, shaped in an extrudate form, and calcined at different temperatures. The catalytic performance of the resulting extrudates in the transesterification depended on not only the active phase type, but also the cluster size of active phase, which was strongly determined by the calcination temperature. Synchrotron-based X-ray micro-computed tomography (micro-CT) was applied for the first time in the development of shaped catalysts. The pore structure of extrudate catalysts obtained at different temperatures was analyzed by nitrogen physisorption measurement, scanning electron microscopy (SEM), and micro-CT, and then correlated with their mechanical properties and catalytic performance. The micro-CT and low-magnification SEM visualized the macroporosity as air voids in the extrudate catalysts. Increasing the calcination temperature from 300 °C to 800 °C decreased the fraction of air voids, resulting in a severe drop of FAME yield due to mass transport problem. The addition of commercial methyl esters into the reaction improved the mass diffusion effectively, and enhanced the biodiesel production. The extrudate catalyst calcined at 300 °C had calcium hydroxide as a main active phase, and the highest macroporosity, which provided a stable FAME yield (>95 wt%) throughout the operation, and a high structural stability

Fabrication of 3D Polycaprolactone Macrostructures by 3D Electrospinning

Building 3D electrospun macrostructures and monitoring the biological activities inside them are challenging. In this study, 3D fibrous polycaprolactone (PCL) macrostructures were successfully fabricated using in-house 3D electrospinning. The main factors supporting the 3D self-assembled nanofiber fabrication are the H 3PO 4 additives, flow rate, and initial distance. The effects of solution concentration, solvent, H 3PO 4 concentration, flow rate, initial distance, voltage, and nozzle speed on the 3D macrostructures were examined. The optimal conditions of 4 mL/h flow rate, 4 cm initial nozzle-collector distance, 14 kV voltage, and 1 mm/s nozzle speed provided a rapid buildup of cylinder macrostructures with 6 cm of diameter, reaching a final height of 16.18 ± 2.58 mm and a wall thickness of 3.98 ± 1.01 mm on one perimeter with uniform diameter across different sections (1.40 ± 1.10 μm average). Oxygen plasma treatment with 30-50 W for 5 min significantly improved the hydrophilicity of the PCL macrostructures, proving a suitable scaffold for in vitro cell cultures. Additionally, 3D images obtained by synchrotron radiation X-ray tomographic microscopy (SRXTM) presented cell penetration and cell growth within the scaffolds. This breakthrough in 3D electrospinning surpasses current scaffold fabrication limitations, opening new possibilities in various fields.</p

Experimental investigation on biodiesel production through simultaneous esterification and transesterification using mixed rare earth catalysts

In this study, biodiesel production through simultaneous esterification and transesterification of palm oil with 10 wt% of oleic acid using the mixed rare earth catalyst was investigated. The mixed rare earth catalysts were prepared via the co-precipitation method. The effects of the precipitating parameters such as temperature, stirring speed and pH on the physicochemical and morphology of the catalysts were studied. All catalysts were thoroughly characterized using X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectrometer (SEM-EDS), fourier transform-infrared spectroscopy (FTIR), N2adsorption/desorption, CO2 temperature programmed desorption (CO2-TPD) and NH3 temperature programmed desorption. (NH3-TPD). The results indicated that the mixed rare earth catalyst prepared under the precipitation conditions: at pH 9, a stirring of 400 rpm and temperature of 30 °C showed the highest catalytic of 90% FAME content. High surface area of the catalyst, a significant larger amount of Ce and La contents in the catalyst and an appropriate amount of acid and basic sites on the catalyst led to the high catalytic activity. The catalyst could also accelerate the initial reaction rate to achieve the high FAME content of 50% within 30 min

Effects of Different Application Times of Silver Diamine Fluoride on Mineral Precipitation in Demineralized Dentin

Silver diamine fluoride (SDF) is a cost-effective method for arresting active dental caries. However, the limited cooperation of patients may lead to an SDF application time that is shorter than the recommended 1–3 min for carious lesions. Therefore, the aim of this study was to assess the effect of different application times of SDF on the degree of mineral precipitation in demineralized dentin. Demineralized dentin specimens from permanent maxillary molars were treated by applying 38% SDF for 30, 60, or 180 s. Water was applied in the control group. The specimens were immersed in simulated body fluid for 2 weeks, and the mineral precipitation in demineralized dentin was then analyzed using FTIR-ATR, SEM-EDX, and synchrotron radiation X-ray tomographic microscopy (SRXTM). The FTIR-ATR results showed a significant increase in mineral precipitation in the 180 s group after 1 week. However, after 2 weeks, the SRXTM images indicated comparable mineral density between the 30, 60, and 180 s groups. The precipitation of silver chloride and calcium phosphate crystals that occluded dentinal tubules was similar in all experimental groups. In conclusion, an application time of either 30, 60, or 180 s promoted a comparable degree of mineral precipitation in demineralized dentin

Characterization of Ancient Burial Pottery of Ban Muang Bua Archaeological Site (Northeastern Thailand) Using X-ray Spectroscopies

Ancient potteries found at Ban Muang Bua, located in northeastern Thailand, associate with Thung Kula Ronghai culture. Most of them are products used in daily life and grave goods. The potsherds were examined using techniques based on X-ray spectroscopy. Elemental composition and morphology were analyzed using proton-induced X-ray emission spectroscopy (PIXE) and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS). Three-dimensional analysis was performed using X-ray tomographic microscopy based on synchrotron radiation (SR XTM). Irregular plate-like particles of composites with a wide range of size distribution were found in the potsherds. The major (O, Si, and Al), minor (C, Fe, Ca, and K), and trace elements (P, S, Ti, Na, Mg, and Zn) which were observed can provide the information about raw materials and production of pottery. The 3D tomographic images show the internal feature of these samples. The combination of SEM-EDS, PIXE, and SR XTM is a powerful tool for archaeological research especially in terms of composition and internal structure. The results imply that the raw materials of pottery were sandy soil derived from marine sands, clays, and salt deposits that were mostly iron-rich-kaolin clay. The production was carried out with low firing temperatures (~600–900 °C) in open-air kilns

Design and optimization of Miura-Origami-inspired structure for high-performance self-charging hybrid nanogenerator

A hybrid piezoelectric-triboelectric-electromagnetic nanogenerator (HPTENG-EMG) has been designed meticulously by focusing on material selection, structural design, and performance evaluation. The module can operate using three parts; piezoelectric, triboelectric and an electromagnetic mechanism. The hybrid concept of triboelectric and piezoelectric is achieved by fabricating triboelectric-piezoelectric composite materials working through the TENG mechanism. In the material design part, the composite film between bacterial cellulose (BC) and BaTiO3 nanoparticles (BT-NPs) fabricates and optimizes its properties with a suitable number of BT-NPs. The unique Miura-Origami (MO) hexagonal multilayer shape is applied within the structural design to increase the contact surface area, which enhances the electrical output signal. The third part of the hybrid system incorporates an electromagnetic generator (EMG) by designing a structure of compact and lightweight cylindrical tubes with magnetic levitation structures. The hexagonal multilayer shape of MO composite TENG (MO-CTENG) generates an open-circuit output voltage (VOC) of ∼414 V and short-circuit output current (ISC) of ∼48.3 μA with maximum output power (P) of about ∼6.94 mW. The highest ISC value of ∼38 mA can be promoted in the optimized EMG, which is higher than the MO-CTENG by ∼786 times. The practical application of this technology is demonstrated by human shaking motion for battery charging in the wireless Global Positioning System (GPS). The maximum direct current output voltage (VDC) saturation of 30 V can be achieved within 19 s. This work provides a potential methodology for increasing electrical output performance by capturing more mechanical energy through the conjunction of three phenomena into a single device, which exhibits a promising way of addressing an energy crisis

Characterization of Ancient Burial Pottery of Ban Muang Bua Archaeological Site (Northeastern Thailand) Using X-ray Spectroscopies

Ancient potteries found at Ban Muang Bua, located in northeastern Thailand, associate with Thung Kula Ronghai culture. Most of them are products used in daily life and grave goods. The potsherds were examined using techniques based on X-ray spectroscopy. Elemental composition and morphology were analyzed using proton-induced X-ray emission spectroscopy (PIXE) and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS). Three-dimensional analysis was performed using X-ray tomographic microscopy based on synchrotron radiation (SR XTM). Irregular plate-like particles of composites with a wide range of size distribution were found in the potsherds. The major (O, Si, and Al), minor (C, Fe, Ca, and K), and trace elements (P, S, Ti, Na, Mg, and Zn) which were observed can provide the information about raw materials and production of pottery. The 3D tomographic images show the internal feature of these samples. The combination of SEM-EDS, PIXE, and SR XTM is a powerful tool for archaeological research especially in terms of composition and internal structure. The results imply that the raw materials of pottery were sandy soil derived from marine sands, clays, and salt deposits that were mostly iron-rich-kaolin clay. The production was carried out with low firing temperatures (~600&ndash;900 &deg;C) in open-air kilns

Balancing current density and electrolyte flow for improved zinc-air battery cyclability

International audienc