Investigation of ZnO nanoparticles for their applications in wastewater treatment and antimicrobial activity

The photocatalytic as well as the antimicrobial activity of the synthesized ZnO nanoparticles (ZnO-NPs) through solution based approach have been presented in this study. ZnO-NPs have been characterised by thermogravimetry/differential thermal analysis (TG/DTA), ultraviolet-visible (UV–Vis), Fourier transform infrared (FTIR) and Raman spectroscopy. Raman studies confirm that it has stable wurtzite structure. FTIR spectrum confirms the Zn–O band at ~460 cm-1. Optical studies reveal that the optical band gap value increases with increasing annealing temperature. The photocatalytic activity of the ZnO-NPs has been evaluated for removal of pollutants from wastewater by measuring COD and BOD. Results show that ZnO-NPs are capable of working efficiently for waste water treatment. ZnO-NPs also demonstrate antimicrobial activity against gram-positive and gram-negative bacterial strains

Synthesis and characterization of dodecanethiol-stabilized gold nanoparticles

Dodecanethiol-stabilized gold nanoparticles of different sizes were synthesized using Bi-phasic reduction method by varying the concentration of stabilizer. These particles were characterized using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-Vis). TEM images show the average particle size of different samples ranging from ~1.7 nm to 5.7 nm. FTIR study confirms the linkage of thiol group and their partial crystalline self assembly onto the surface of nano gold particles. From the UV-Vis spectra, it is noticed that absorption peak position is sensitive to the size of the particles. Theoretical fit for absorbance spectra was obtained using Mie theory and the deviation from experimental results demonstrates the large size and shape distribution. A linear relationship between logarithms of extinction coefficient and particle diameter is obtained, which explains the extinction coefficient dependence on the size of the particle

Synthesis, characterization and potential sensing application of carbon dots synthesized via the hydrothermal treatment of cow milk

Abstract Carbon quantum dots (CQDs) were synthesized in this study by hydrothermally treating cow milk. The procedure is simple, non-hazardous to the environment, and does not necessitate the use of any special instruments or chemicals. CQDs were practically almost circular when they were manufactured and had an average size of 7 nm. Carbon (67.36%), oxygen (22.73%), and nitrogen (9.91%) comprised the majority of their composition. They feature broad excitation-emission spectra, excitation-dependent emission, and temperature-dependent photoluminescence. They remained quite stable in the presence of a lot of salt, UV radiation, and storage time. Because luminescence quenching mechanisms are sensitive to and selective for Sn2+, they can be employed to create a nanosensor for detecting Sn2+

Dielectric properties of surface stabilized ferroelectric liquid crystal mixture - Effects of dichroic dye

657-666<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">The dielectric permittivity of ferroelectric liquid crystal mixture FLC-6980 doped with a low concentration of anthraquinone dye has been studied. The complex permittivity has been measured in the frequency range 100 Hz to 1MHz in SmC* and SmA phase. We report the observation of relaxation modes. Dielectric increments and the relaxation frequencies at various temperatures have also been evaluated. Our results indicate that the relaxation frequency and the SmC*-SmA transition temperature TC*A decrease whereas the dielectric increment increases by about 2.5 times on ~2 % wt/wt dye addition.</span

Synthesis and optical properties of GdVO4: Eu3+ phosphor

In the present work, we have synthesized GdVO _4 doped Eu ^3+ using a facile sol-gel method and analysed the effect of concentration variation and annealing temperature on the optical properties. Tetragonal (I4 _1 /amd) zircon type crystal structure of the material was confirmed by x-ray diffraction (XRD) study. The photoluminescence (PL) spectra were recorded with an ultraviolet (UV) excitation of wavelength 325 nm. GdVO _4 doped Eu ^3+ (1 mol%) gives prominent red emission. This optimized sample was annealed at different temperature and as annealing temperature raises, the crystallinity of the material increases resulting in the improved emission intensity. The emission spectra of this phosphor exhibit intense peaks at wavelengths 593 nm (orange) and 618 nm (red) which corresponds to ^5 D _0 - ^7 F _1 , ^5 D _0 - ^7 F _2 transitions of Eu ^3+ ions. ^5 D _0 - ^7 F _2 , the electric dipole transition is dominant indicating that Eu ^3+ ions situated at a non-centrosymmetric site in the crystal structure. GdVO _4 : Eu ^3+ (1 mol%) annealed at 800 °C gives eminent red emission which can be further used as the potential candidate for bioimaging, lighting, temperature sensing and display devices

Synthesis and characterization of dodecanethiol-stabilized gold nanoparticles

93-100Dodecanethiol-stabilized gold nanoparticles of different sizes were synthesized using Bi-phasic reduction method by varying the concentration of stabilizer. These particles were characterized using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-Vis). TEM images show the average particle size of different samples ranging from ~1.7 nm to 5.7 nm. FTIR study confirms the linkage of thiol group and their partial crystalline self assembly onto the surface of nano gold particles. From the UV-Vis spectra, it is noticed that absorption peak position is sensitive to the size of the particles. Theoretical fit for absorbance spectra was obtained using Mie theory and the deviation from experimental results demonstrates the large size and shape distribution. A linear relationship between logarithms of extinction coefficient and particle diameter is obtained, which explains the extinction coefficient dependence on the size of the particle

Polarization switching and dielectric relaxations in ferroelectric Smectic C liquid crystal mixtures

429-433<span style="font-size: 15.0pt;mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif""="">Polarization switching responses and dielectric measurements have been carried out on two ferroelectric liquid crystal mixtures in planar cell s. The rotational and bulk torsional viscosities have been calculated. These viscosities show Arhenius type behavior. The activation energies of these materials evaluated from viscosity data have been found to be <span style="font-size:16.0pt;mso-bidi-font-size: 9.0pt;font-family:" times="" new="" roman","serif""="">0.32 eV and <span style="font-size: 16.0pt;mso-bidi-font-size:9.0pt;font-family:" times="" new="" roman","serif""="">0.37 eV. The spontaneous polarization has been measured using field reversal method. These mixtures show switching times of <span style="font-size:16.0pt; mso-bidi-font-size:9.0pt;font-family:" times="" new="" roman","serif""="">~40μs. </span