H. Nandakumar Sarma

Elemental Content of Some Anti-Diabetic Medicinal Plants Using PIXE Analysis

Elemental analysis of some selected medicinal plants of northeast India having anti-diabetic property was conducted using proton-induced X-ray emission (PIXE) technique. Plant samples were excited with a 2.4-MeV proton beam from a 3-MV Tandetron accelerator, and the spectral data were analyzed by using GUPIX, a software package for fitting PIXE spectra from layered specimens. The elements K, Ca, Mn, Fe, Ni, Cu, Zn, Rb, and Sr were identified and concentrations determined. No toxic heavy metals were found in the plants. The accuracy and precision of the technique were assured by analyzing standard reference materials. Results indicated that the analyzed medicinal plants could be considered potential sources for providing a reasonable amount of the required elements along with other food items to diabetes mellitus patients.

PARTICLE INDUCED X-RAY EMISSION STUDIES OF SOME INDIAN MEDICINAL PLANTS

Medicinal herbs have been used from antiquity by humanity. This paper discusses the elemental composition and concentration of ten Indian medicinal plants investigated by particle induced X-ray emission (PIXE) technique. The accuracy and precision of the technique were assured by analyzing three Certified Standard Reference Materials-cabbage (GBW 08504, China), wheat flour (NIST-8436) and bovine liver (NIST-1577b). The elements K, Ca, Mn, Fe, Cu and Zn were found to be present in all the samples in varying concentrations. No toxic heavy metals such as As, Pb and Hg were detected in the studied plants. The range of the elemental concentrations in dry weight has been found to vary from 4.69 × 104mg/kg to 1.81 mg/kg in the plants. The results also show that these plants contain elements of vital importance in mans metabolism and that are needed for growth and developments, prevention and healing of diseases.

X-ray—A boon for elemental analysis

The characteristic X-rays coming out from an unknown sample due to the irradiation of gamma rays or X-ray photons or due to the bombardment of high velocity protons are used for elemental analysis in a sample. We describe here two techniques viz., Energy Dispersive X-Ray Fluorescence (EDXRF) and Proton Induced X-ray Emission (PIXE) which have the capability of nondestructive and multi-elemental analysis of the sample.

Effect of Mn 2+ Doping on Structural, Morphological and Optical Properties of ZnS Nanoparticles by Chemical Co-Precipitation Method

Zinc Sulphide (ZnS) nanoparticles doped with different concentrations of Mn 2+ (0%, 2%, 4%, 6%, 8%, 10%) have been synthesized by chemical co-precipitation method using polyvinyl alcohol (PVA) as a capping agent to control the particle growth. The structural characterizations of as synthesized nanoparticles are determined by X-ray diffraction (XRD) which showed cubic zinc blende structures with average crystallite sizes of the range 2.3 nm - 2.1 nm. There is no phase transformation due to Mn 2+ doping and this characteristic has been observed in all the synthesized powder. Scanning electron microscopy (SEM) and energy dispersive X- ray (EDX) analysis show the morphology and elemental analysis of as synthesized nanoparticles.TEM images confirms the spherical shape of the nanoparticles. HRTEM and SAED images show the crystalline nature and confirm the cubic nature of ZnS nanoparticles. Absorption study has been carried out by using UV-Vis spectrophotometer to determine the band gap of ZnS:Mn nanoparticles and they showed a blue shift with respect to the bulk. The effect of Mn 2+ substitution on the photoluminescence properties of doped samples is also studied and doped ZnS:Mn showed enhanced luminescence property compared with that of the undoped ZnS nanoparticles. Radius of the synthesized nanoparticles has been evaluated from the absorption spectrum by using the Effective Mass Approximation (EMA) formula. Fourier Transform Infrared Spectra (FTIR) is recorded in an FTIR spectrometer to verify the presence and effect of capping agent.

Synthesis and Photoluminescence Studies of Ni Substituted ZnO Nanoparticles

Nickel (Ni) substituted ZnO nanopowders were synthesized by simple and efficient co-precipitation method with zinc nitrate and nickel nitrate as the starting materials. Effect of Ni substitution on structural and photoluminescence properties of ZnO nanopowders has been studied. Structural characterization of the as prepared powders was performed with X-ray diffraction (XRD) studies. It was confirmed that all the powders were of zinc oxide having polycrystalline nature and possessing typical hexagonal wurtzite structure. Both lattice parameters a and c decreases from 3.257 to 3.214 A and 5.217 to 5.156 A, respectively with increase in Ni content from 0 to 10 wt % while the crystallite size calculated from the XRD data decreases from 29.8 to 14.2 nm, respectively. The effect of Ni substitution on the photoluminescent properties of ZnO nanopowders was also studied in order to exploit their possible application in nanoscale optoelectronic devices. The synthesized ZnO nanopowder samples showed a broad UV photoluminescence (PL) emission peak at 3.14 eV.

Synthesis, Structural and Optical Characterization of PVA Capped Cadmium Sulphide Nanocrystalline Films by Chemical Bath Deposition Method

Nanocrystalline CdS thin films were deposited on glass substrate by chemical bath deposition method using Cadmium Sulphate and Thiourea as Cd+2 and S-2 ion sources for different molarities i.e. 0.1 M, 0.2 M and 0.3 M. The crystallite size and lattice parameters for each sample were determined from X-Ray diffraction data using Scherrers formula. The value of the crystallite size was found to be within the range 14.7 nm-11.4 nm. The optical characterization was done by UV-Visible and photoluminescence spectroscopy. The optical band gap of the films was determined from the transmittance spectra. It was observed that when the molarity increases, the average crystallite size decreases and the band gap energy of the prepared films increases. Photoluminescence studies showed a prominent peak at around 530 nm. The radius of the nanocrystalline films had been evaluated from the absorption spectrum by using effective mass approximation formula.