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Synthesis of nitrogen-doped carbon dots (N-CDs) using urea and ascorbic acid as carbon sources is addressed in this study using a microwave-assisted hydrothermal technique. The samples were characterized by ultraviolet, photoluminescence (PL) and transmission electron microscopy analyses, which confirmed the formation of CDs. Besides PL properties, the peroxidase-like catalytic activity of the CDs and N-CDs was also compared. Interestingly, the N-CDs exhibit higher peroxidase-like catalytic activity than pure CDs and can be used to detect H2O2. Additionally, we synthesized several N-CD ratios and evaluated their peroxidase-like catalytic activity. [ABSTRACT FROM AUTHOR]

The effect of Al substitution on electromagnetic properties has been studied for nanocrystalline MgCuMnAlFeO ferrites, wherein x varies from 0 to 0.4 in steps of 0.1. These ferrites were synthesized by using microwave hydrothermal method and then characterized using X-ray diffractometer (XRD), Fourier transform infrared and transmission electron microscopy. The synthesized powders were densified using microwave sintering method at 950C/50 min. Structural and surface morphology of sintered samples were characterized using XRD and atomic force microscopy, respectively. The complex permittivity and permeability properties were measured over a frequency range 100 Hz-1.8 GHz. The temperature variation of magnetic properties were measured in the temperature range of 300-650 K. The electrical and magnetization studies inferred that the values of d.c. resistivity increases by 27%, whereas saturation magnetization decreases linearly from 38.6 to 23.0 emu g and Curie temperature was found to be decreased from 628 to 513 K with an increase of Al ions. The low dielectric, magnetic losses, moderate saturation magnetization and high-temperature stability properties exhibited by Al substituted MgCuMn ferrites make them find applications in microwave devices, such as circulators and isolators etc. The applicability of present samples for microwave devices has been tested by the measurement of ferromagnetic resonance linewidth at K band. [ABSTRACT FROM AUTHOR]

Mesoporous γ-alumina was synthesized by the microwave-hydrothermal process with a shorter duration time at 150∘C/2 h followed by calcination at 550∘C/1 h. Ag nanoparticles (AgNPs) were impregnated into γ-alumina under a reducing atmosphere at 450∘C. The synthesized product was characterized by X-ray diffraction (XRD), thermogravimetric (TG)/differential thermal analysis (DTA), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption study, field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The BET surface area values of γ-alumina and Ag-impregnated γ-alumina were found to be 258 and 230 m2 g-1, respectively. FESEM images showed the formation of grain-like particles of 50-70 nm in size with a flake-like microstructure. The XRD, XPS and TEM studies confirmed the presence of Ag in the synthesized product. Catalytic properties of the product for CO oxidation was studied with the T50 (50% conversion) and T100 (100% conversion) values of 118 and 135∘C, respectively; the enhanced values were compared with the literature reported values. [ABSTRACT FROM AUTHOR]