3.Conference Paper (10)

Permanent URI for this collectionhttps://dspace.psgrkcw.com/handle/123456789/3914

Browse

Now showing 1 - 10 of 10

DECORATION AND FUNCTIONALIZATION OF GRAPHENE OXIDE NANOCOMPOSITES FOR SENSING APPLICATIONS
(Elsevier, 2019) Ramalakshmi, V; Balavijayalakshmi, J
In the present work, β-cyclodextrin functionalized reduced graphene oxide-silver nanocomposites (GO-β-CD-Ag) are effectively synthesized using wet chemical method. The GO-β-CD nanocomposites are initially produced via hydrazine reduction. The various concentrations (0.002 M, 0.004 M, 0.006 M, 0.008 M and 0.01 M) of silver nanoparticles are decorated on the GO-β-CD surface by the reduction of silver nitrate with sodium borohydrate as a reducing agent. The produced GO-β-CD-Ag nanocomposites are well characterized using XRD, SEM and EDAX analysis. The XRD results firmly established that the β-CD molecules are satisfactorily coated on the rGO surface and also the Ag nanoparticles with an average size of 23 nm are evenly decorated on the GO-β-CD surface. The GO-β-CD-Ag nanocomposites modified glassy carbon electrode is captivated for the selective detection of o-Nitrophenol. Cyclic voltammetry test is employed to determine the presence of o-Nitrophenol compound. The result shows the oxidation and reduction potential for o-Nitrophenol at -0.25 V and -0.5 V respectively, indicating the successful determination of o-Nitrophenol by using the GO-CD-Ag nanocomposite modified electrode.
EFFECT OF ULTRASONICATION DURING AND AFTER PREPARATION OF BIVO4 BY CHEMICAL COPRECIPITATION TECHNIQUE
(Elsevier, 2019) Deebasree, J P; Maheskumar, V; Vidhya, B; Balaji, G
Bismuth vanadate (BiVO4) was prepared by ultrasonic assisted coprecipitation method. The photocatalytic activity of BiVO4 was tested under visible light irradiation for the degradation of MB. The properties of BiVO4 prepared by coprecipitation is compared with samples prepared using ultrasonic assisted coprecipiation and an optimal ultrasonic power output yielding better photocatalytic activity is identified. The properties like crystallinity, morphology were studied to understand its effect on photocatalytic property. The sample sonicated with 160 W during preparation yielded better catalytic efficiency (90% degradation of Methylene blue). The improved catalytic activity could be due to the inhibition of electron-holes recombination.
ENHANCED CORROSION RESISTANCE OF MILD STEEL IN SULPHURIC ACID MEDIUM BY IMIDAZOLE DERIVATIVE: EXPERIMENTAL AND COMPUTATIONAL STUDIES
(Elsevier, 2019) Sowmya, Ramkumar; Nalini, D
The inhibition action of the imidazole derivative on the corrosion of mild steel in 0.5 M Sulphuric acid was investigated by weight loss, polarization, Impedance and SEM. The PZC of mild steel was studied by AC impedance method. The polarization experiment revealed that IDZ is of mixed–type but slightly anodic control. Weight loss results obtained revealed that the imidazoline derivatives performed excellently as corrosion inhibitor with efficiency above 70% at 20ppm at 303 K. The optimum period of inhibition for IDZ was determined by weight loss studies. Its adsorption on mild steel obeys Tempkin isotherm. Quantum chemical parameters and Mulliken charge densities on the optimized structure of imidazoline derivative were calculated using GAUSSIAN 09 with B3LYP / 6-31G (d,p) basis set
A FACILE APPROACH FOR THE SYNTHESIS OF CARBON DOTS FROM HIBISCUS SABDARIFFA & ITS APPLICATION AS BIO-IMAGING AGENT AND CR (VI) SENSOR
(Elsevier, 2019) Komalavalli, L; Amutha, P; Monisha, S
An eco-friendly approach to yield fluorescent carbon dots (C-dots) from bio-precursors has received a fascinating impact on its application as heavy metal ions sensors & bio-imaging agent. The C-dots have been synthesised by hydrothermal method from Hibiscus sabdariffa and characterised by IR, TEM, UV and photo luminescent spectral studies. This approach is evident to be facile, cost-effective and non– toxic with unremitting water solubility. The blue luminescent C-dots formed reveals excitation and size dependent photo luminescent behaviour. The as-prepared C-dots have been applied to detect Cr (VI) ions in aqueous solution. Also, the cyto-toxicity and bio-imaging ability of the C-dots were examined using breast cancer cells (MDA-MB 231 cell lines). The studies affirmed low toxicity & excellent bio-imaging potentiality of the C-dots.
GRAPHENE BASED NANOCOMPOSITES FOR ELECTROCHEMICAL DETECTION OF H2O2
(Elsevier, 2019) Yuvashree, S; Balavijayalakshmi, J
In this study, a novel reduced graphene oxide-based nanocomposite electrochemical biosensor for the reliable detection of H2O2 is developed. Reduced graphene oxide-chitosan nanocomposites are successfully prepared by chemical reduction method. XRD, FT-IR, SEM and EDAX analysis are performed to characterize the structural, spectral, morphology and composition of the prepared nanocomposites. The response of the modified electrode to H2O2 is examined by cyclic voltammetry. Under optimal experimental conditions, the RGO-CS biosensor showed outstanding catalytic activity toward H2O2 reduction. The H2O2 reduction peaks are observed about 0.1V. These results confirm that RGO-CS nanocomposites with the high surface area and electrocatalytic activity offer a promising candidate for the detection of H2O2 in biological environment.
GREEN SYNTHESIS OF SILVER NANOPARTICLES (AG NPS) USING GOMPHRENA GLOBOSA (GLOBE AMARANTH) LEAF EXTRACT AND THEIR CHARACTERIZATION
(Elsevier, 2019) Tamilarasi, P; Meena, P
Among the various methods explored for the synthesis of silver nanoparticles (Ag NPs), the green synthesis method has received great attention as a cost effective and environmental friendly method as it avoids toxicity. In the present work, silver nanoparticles were synthesized using silver nitrate as the precursor and an aqueous extract of fresh leaves of Gomphrena globosa (Globe amaranth) as the reducing and stabilizing agent. The active phytochemicals present in the leaves cause quick reduction of silver ions (Ag+) to metallic silver nanoparticles (Ag0). The formation of Ag nanoparticles was initially confirmed by visual observation through the color change of the mixture. The silver nanoparticles obtained were characterized using UV–visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR), Scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDAX), High-resolution transmission electron microscopy (HR-TEM), and Selected area electron diffraction (SAED) analysis. The synthesized silver nanoparticles show excellent antibacterial activity against three gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis, Micrococcus luteus) and three gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae).
GROWTH, STRUCTURAL, DIELECTRIC AND OPTICAL CHARACTERISTICS OF GLYCINE PHOSPHITE SINGLE CRYSTALS
(Elsevier, 2019) Shanmuga Sundari, S; Kanchana, P; Arunadevi, N; Shobana, C
Interesting compounds are formed when glycine reacts with inorganic materials. These compounds exhibit phase transitions with exciting dielectric and elastic properties. In this aspect, glycine with orthophosphorus acid forms glycine phosphite (GPI) single crystals. Good quality, optical transparent glycine phosphite (GPI) single crystals are grown from aqueous solution. GPI crystals have a wide range of nonlinear optical applications. The present work focuses on the growth of GPI from its aqueous solution by slow evaporation method. The PXRD (powder XRD) pattern recorded at ambient temperature shows the single phase nature of the grown GPI crystals and it exists in the monoclinic system with space group P21/a. Etching studies were carried out to know more about the growth morphology and FTIR spectra shows the presence of a variety of normal mode vibration of GPI crystals. Dielectric studies were carried out from 100 K to 383 K. the ferroelectric to para electric transition was observed at 201 K. The dielectric relaxation of the grown crystals was studied using Debye fitting. The activation energy associated with the transition was also calculated. As the GPI crystals are paraelectric at room temperature, no second order non linearity was observed.
IMPACT OF ALUMINIUM ON “STRUCTURAL, OPTICAL AND MORPHOLOGICAL PROPERTIES OF COPPER OXIDE NANOPARTICLES”
(Elsevier, 2019) Vidhya priya, P; Balavijayalakshmi, J
Metal-oxide-semiconductors have been widely used for the optoelectronic applications like smart windows, solar cells, light emitting diodes and flat panel displays. Among all the metal oxides, copper oxide nanomaterials have a great attention due to its unique properties. It is mostly used in recent research works because of its low cost, rich availability and used in latent applications like antibacterial activities. Aluminium nanoparticles are a good conductor and it enhances the conductivity. Hence an attempt is made to synthesize CuO and Al doped CuO nanoparticles by hydrothermal method. The prepared samples are characterized by XRD, FT-IR, SEM, UV-Vis and PL analysis.The crystallite structures of CuO and Al doped CuO nanoparticles are identified by XRD analysis. The Fourier transform Infrared spectroscopy is used to determine the functional groups present in the prepared nanoparticles. UV-Vis Spectral analysis is performed to determine the band gap energy of the synthesized nanoparticles. PL spectral studies are used to study the optical properties of the nanoparticles. The morphology of the samples is determined by using scanning electron microscopy analysis. The impact of aluminium on structural, optical and morphological properties is investigated. The antibacterial activities of prepared CuO and Al doped CuO nanoparticles are probed.
OPTICAL AND BIOLOGICAL CHARACTERISTICS OF NOVEL ORGANIC SINGLE CRYSTAL 4-CHLORO N-METHYL 4-STILBAZOLIUM TOSYLATE
(Elsevier, 2019) Arunadevi, N; Kanchana, P; Mehala, M; Shanmuga Sundari, S
When compared with inorganic materials, the molecular organic materials acquire significant interest because of their considerable nonlinear optical properties, virtual unlimited design possibilities and extremely fast response times. Amongst them, organic crystals which are based on the charged chromophores and substantial Coulomb interaction have a number of benefits over non-ionic species, like first-order hyperpolarizability or greater molecular nonlinearity, durable stability and having a larger capability to override the dipole–dipole interactions and therefore it forms a non-centro symmetric macroscopic packing. For instance, DAST (4-N, N-dimethylamino-4′-N′-methyl-stilbazolium tosylate), the organic salt crystal, is one of the finest nonlinear optical materials having larger second-order nonlinear optical susceptibilities. Even though benchmark stilbazolium crystals display a great macroscopic nonlinearity and noble crystal characteristics, improving these physical properties comprising the environmental stability is a provocative topic. Based on this, the present paper discusses the growth of cationic substituted DAST namely 4-chloro -N-methyl 4-stilbazolium tosylate (CMST). Knoevenagel reaction method was used to synthesis CMST salt using Dean-Stark apparatus. The synthesized salt of CMST was dried at 100 °C for 24 h. The dried CMST salt was used to grow the crystals after three recrystallization process. Based on the solubility curve new solvent, mixture of methanol and acetonitrile was used to grow the crystals at room temperature by slope nucleation method. Structure of the grown crystals was characterized using single crystal XRD and FTIR. The compositional analysis was carried out using NMR and CHN analysis. Luminescence characteristics was studied using photoluminescence spectrum. The dielectric characteristics ware carried out from room temperature to 250 °C. Invitro analysis was carried out in the cancer cell line to study it’s anti-cancer activity.
TIGHT FOCUSING PROPERTIES OF PHASE MODULATED AZIMUTHALLY POLARIZED DOUGHNUT GAUSSIAN VORTEX BEAM BY HIGH NA PARABOLIC MIRROR
(Elsevier, 2019) Umamageswari, N; Lavanya, M; Udhayakumar, M; Rajesh, K B; Zaroszewicz, Z
The intensity distribution in the focal region of a high NA parabolic mirror for the incident azimuthally polarized doughnut Gaussian vortex beam (DGVB) transmitted through a multi belt complex phase filter (MBCF) is studied using vector diffraction theory. By properly designing the phase of the incident beam using MBCF and by tuning the beam parameters of a DGVB, it is possible to switch the focal spot with sub wavelength dimension and long focal depth in to multiple focal spots suitable for particle acceleration, atom optical experiments, and near-field scanning optical microscopy.