Nano

Metal nanoparticles use a biocompatible, environmentally sustainable approach to be used as therapeutic nanomedicine. This study describes the use of rosaceous fruit peel waste extract (plum, kiwi, peach) as a tool for the synthesis of silicon nanoparticles. Visual color shift was used to identify biosynthesized SiO₂NPs at first. Some characterization techniques, such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and SEM analysis, verified the existence of these metal nanoparticles. The presence of various functional groups from the extract secondary metabolites for nanoparticle synthesis is suggested by FT-IR spectroscopy. The existence of SiO₂ nanoparticles, whether crystalline or amorphous, is hypothesized using XRD. The formation of SiO₂ nanoparticles was confirmed by UV–Vis spectroscopy. The zeta potential shows the nanoparticles stability. Different fruits peels produced different shapes and sizes of SiO₂NPs. Plum peels extract produced the smallest SiO₂NPs, followed by kiwi and peach as determined by SEM analysis. Antibacterial and antioxidant activities were also tested on all of the synthesized SiO₂NPs. Regardless of size; these nanoparticles have stronger antibacterial activity against gram-negative bacteria. All SiO₂NPs’ antioxidant activity was measured in a size and dose-dependent manner. To summarize, the current environmentally friendly method for the synthesis of SiO₂NPs nanoparticles is a simple and economical process with good antibacterial and antioxidant properties.

Piezoelectric energy harvesters are used to extract and generate electrical energy from ambient vibration sources. Under low excitation, the efficiency of the rectifier plays an important role in determining the efficiency of energy harvesters. Asymmetric Synchronous Electric Charge Extraction (ASECE) has higher efficiency compared to other conventional rectifiers. In this paper, the subcircuits of ASECE, i.e., peak detector and zero crossing detector, are designed. The proposed detectors can operate even at minimum frequency of 10Hz and in the temperature range of 0–125^∘C. The proposed peak detector has shown detection in subthreshold region also. The performance of these detectors at different temperatures, supply voltages and frequencies has been reported in this paper. The detectors are designed using Tanner (2019.2) EDA tool at 180nm CMOS technology.

This is a comparative study of supercapacitor performance of CeO₂/PANI composite electrode prepared by two different synthesis methods, namely, in situ polymerization and solution mixing. The chemical composition of materials was confirmed by X-ray diffraction (XRD). The electrochemical studies such as cyclic voltammetry (CV), charge–discharge, electrochemical impedance and cyclic test of the composite were studied in two symmetrical electrode systems in an aqueous electrolyte medium. The CeO₂/PANI (CP10) composite prepared by in situ polymerization has resulted in better specific capacitance than solution mixing in an aqueous electrolyte (0.5M H₂SO₄) with the capacitance value of 240F/g at 0.5A/g. The in-situ polymerization method evenly spreads polyaniline (PANI) all over the cerium oxide (CeO₂) material and reduces charge transfer resistance ($R_{\mathrm{\text{ct}}}$) which is lacking in the solution mixing method. After 4000 cycles at 5A/g, the CP10 composite retained 72.8% of capacitance retention and energy density of 33.33Wh/Kg at power density of 249.87W/Kg.

Research in green synthesis of metallic nanoparticles and their applications in engineering, food, biomedicine and agriculture is growing rapidly. The presence of biologically active metabolites in fungi makes them ideal candidates for green synthesis of silver nanoparticles (AgNPs). This study aims at discerning an emerging applicability of a basidiomycete mushroom, Phaeolus schweinitzii, for mycosynthesis of AgNPs and their antimicrobial properties. The colour change in P. schweinitzii aqueous extract was used to detect and curate the synthesis of AgNPs. The AgNP surface plasmon resonance (SPR) was observed in the visible spectra at approximately 428nm using UV-Vis spectroscopy. The XRD spectrum revealed a face-centered cubic (FCC) structure of AgNPs with an average crystallite size of 38.78nm. FT-IR manifested various functional clusters of biomolecules which were involved in bioreduction, capping and stabilization of AgNPs. FE-SEM imaging of AgNPs revealed a spherical shape with an average size of 88.65nm. The synthesized AgNPs showed strong antimicrobial activities against Salmonella gallinarum, E. coli, Staphylococcus aureus, Aspergillus niger and Fusarium oxysporum with varying zones of inhibition at different concentrations. The highest concentration (5mg/ml) of AgNPs produced a maximum zone of inhibition ($13.33\pm 0.57$mm) against gram negative bacteria (Salmonella gallinarum and E. coli) and lowest ($11.66\pm 0.57$mm) against gram positive bacteria (Staphylococcus aureus). The study also revealed that synthesized AgNPs showed comparatively higher antifungal activity than the positive control (nystatin). The findings from this study explicitly concur with the ever-relevant use of biogenic AgNPs against various pathogenic microorganisms.

Two kinds of CuO nanomaterials with different morphologies were grown directly on surface of nickel foam using electrochemical deposition technology, and their electrochemical properties were studied. The morphology of CuO at different deposition voltages (spherical and wheat spike) were observed by field emission scanning electron microscopy. The results showed that the deposition voltage is the main factor affecting the morphology of CuO. In addition, X-ray diffraction results showed that the prepared samples are CuO materials. The electrochemical properties of CuO nanostructures were studied by cyclic voltammetry, galvanostatic charge/discharge measurements and electrochemical impedance spectroscopy. These test results showed that the specific capacitance of CuO nanomaterials was largely related to the morphology of the material. Compared with CuO nanospheres thin films, wheat spike CuO thin films had a more prominent specific capacitance. The wheat spike CuO array film has a specific capacitance of 120mF/cm² at a current density of 1mA/cm² in 1mol/L sodium sulfate electrolyte.

Carbon dots (CDs), as an emerging carbon material, have attracted considerable interest for their promising luminescent properties. However, the inevitable aggregation of CDs in solid-state results in some bottleneck problems such as aggregation-induced quenching and foster resonance energy transfer. Therefore, developing solid-sate CDs with good luminescent performance is still a challenge. Herein, a simple and low-cost approach is presented to prepare the solid-state CDs/SiO₂ composite in which the CDs were well dispersed and embedded in inorganic silica gel, hence restraining the natural issues of the solid-state CDs. As expected, the CDs/SiO₂ composite phosphors showed higher fluorescence intensity about twice than the CDs aqueous solution, and a high photoluminescence quantum yield of 21%. This work would be of significance for the preparation of CDs and even their practical applications.

TiO₂ nanotube arrays (NTbs) have been widely used in the field of photocatalysis due to their large surface area, good controllability and superior electron transport properties. However, due to its wide bandgap (3.2eV), pure TiO₂ can only be excited by ultraviolet light ($\lambda <387$nm), leading to low utilization of solar energy. Second, the high recombination rate of the photogenerated electrons and holes ($e^{-}$/$h^{+})$ pair also reduces the quantum efficiency of TiO₂. In order to realize the efficient photocatalytic activity of TiO₂ nanomaterials, it is necessary to design the TiO₂ nanomaterials to optimize the utilization of the solar spectrum. In this study, TiO₂ NTbs were obtained by the anodizing method using titanium foil, and a series of Co/TiO₂ NTbs were prepared by electrochemical deposition. The effects of the deposition voltage on the physical and photocatalytic properties of the Co/TiO₂ NTbs were investigated. Results found that the Co/TiO₂ NTbs had the highest photocurrent density 0.7mA/cm² at an electrodeposition time of 60s and a voltage of 1V, and the photoelectric conversion efficiency was 15.85%, which was approximately 2.8 times that of the pure TiO₂ NTbs. The degradation rate of Rhodamine B of the Co/TiO₂ NTbs in 120min was 76.3%, whereas that of the pure TiO₂ NTbs was only 48.7%. The forbidden bandwidth of the Co/TiO₂ NTbs was reduced to 3.02eV, whereas that of the pure TiO₂ NTbs was 3.2eV.