Ayaz Arif Khan

Influence of preparation method on structural, optical and magnetic properties of nickel ferrite nanoparticles

Abstract Nanocrystalline NiFe2O4 particles were prepared by conventional sol-gel, citrate-nitrate sol-gel combustion and co-precipitation methods. The synthesized samples were annealed at 1000 °C for two hours and structural, chemical, morphological, optical and magnetic properties of nickel ferrite were investigated. The structural properties were investigated by X-ray diffraction (XRD) technique which confirmed the formation of single phase NiFe2O4 particles derived by the three methods. The chemical properties were analyzed by Fourier transform infrared (FT-IR) spectroscopy which confirmed the corresponding vibration modes in the samples. The optical properties were studied by UV-Vis spectroscopy. The morphological study of the as-synthesized samples was carried out by scanning electron microscopy (SEM). SEM images showed the agglomerated nanoparticles of NiFe2O4. The magnetic properties were investigated by vibrating sample magnetometer (VSM), which showed that the calcined samples exhibited typical magnetic behavior.

Modeling and Analysis of Thermal Damping in Heat Exchanger Tube Bundles

Most structures and equipment used in nuclear power plant and process plant, such as reactor internals, fuel rods, steam generator tubes bundles, and process heat exchanger tube bundles etc., are subjected to Flow Induced Vibrations (FIV). Costly plant shutdowns have been the source of motivation for continuing studies on cross-flow induced vibration in these structures. Damping has been the target of various research attempts related to FIV in tube bundles. A recent research attempt has shown the usefulness of a phenomenon termed as “thermal damping”. The current paper focuses on the modeling and analysis of thermal damping in tube bundles subjected to cross-flow. It is expected that the present attempt will help in establishing improved design guidelines with respect to damping in tube bundles.Copyright

Influence of Temperature on the Morphology and Grain Size of Cupric Oxide (CuO) Nanostructures via Solvothermal Method

Cupric oxide (CuO) nanostructures have been synthesized successfully through solvothermal chemical route. The influence of temperature on the morphology and the grain size of CuO have been investigated. Phase analysis of synthesized CuO has also been carried out using X-ray diffraction (XRD). XRD peaks showed the monoclinic crystalline phase of CuO nanostructures. The morphology of CuO has been studied by using Scanning Electron Microscope (SEM). SEM images showed the rod-like and sheet-like morphology of CuO. Fourier Transform Infrared (FTIR) spectroscopy has been employed to study the vibrational modes. The FTIR spectra confirmed the stretching vibrations of Cu-O bond. In addition, UV-visible absorption spectra have been implemented to estimate the energy bandgap of the synthesized CuO nanostructures. The energy bandgap of as prepared CuO nanostructures was estimated between 2.0 eV to 2.52 eV. The grain size was found to be increasing with the rise in temperature. The increase in grain size with increasing temperatures causes the reduction in the bandgap, which is attributed to the quantum confinement effect at smaller particle size.

Inv estigation of Genetic Diversity among Medicago species Using RAPD Markers

Aims: Medicago is known as the Queen of forage with potential economic importance to our society. The present study aimed at the use of RAPD-PCR DNA marker to identify the genetic fingerprints affinities of six species of Alfalfa. Place and Duration of Study: The study was conducted at the Department of Genetics, Garden Campus, Hazara University, Mansehra Pakistan during February, 2011 to August, 2013. Methodology: In this study, six species of Medicago namely TWAL (Tetraploid Wisconsin Alfalfa Line), Medicago arborea, Medicago falcata, Medicago sativa, Medicago lupulina and Medicago polymorpha were used to explore the diversity of alfalfa. Seven out of 120 decamers produced 34 polymorphic loci with 100% polymorphism to identify the different species of Medicago crop. The Original Research Article Murtaza et al.; BBJ, 6(2):79-86, 2015; Article no.BBJ.2015.029 80 range of polymorphic loci was observed from 300 to 700 bp. Eleven species specific loci were generated by seven decamers. Primer B-18 generated single specific locus 700 bp against genomic DNA of M. lupulina and it is important to identify particular species of Alfalfa. The bivariate data were recorded as the presence of locus 1 and absence 0 and then this data was transferred into A and C respectively to make it suitable for DNAMAN software (version 5.2.2.0; Applied Biostatistics Inc). Moreover, cluster analysis was performed using sequence alignment and divergence function of the DNAMAN against the bivariate data collected from the products of decamers. All members clustered in a unique pattern except M. falcata and M. lupulina those shared 86% homology. Three distinct groups were observed during UPGMA (Unweighted pair Group Method with Arithmetic Mean). During the phylogenetic study, TWAL was observed to have genetic diversity from other five species of Alfalfa. Conclusion: So, the present study is enabling us to discriminate different species of Alfalfa and it could be useful to identify and authenticate different species of the same genus of medicinal important plant from the Flora of Pakistan.

Solvothermal synthesis of luminescent bis-(8 hydroxy quinoline) cadmium complex nanostructures

A facile solution- based route for the synthesis of Bis- (8- hydroxyquinoline) Cadmium (CdCh) complex nanorods, nanoflowers (bundles of nanorods) and nanosheets in an oleic acid- sodium oleate- ethanol- H2O system at 50°C -100°C was reported. Scanning Electron Microscope (SEM) images indicated that longer time and higher temperature would result in nanoflowers, while lower temperature and shorter reaction time would be suitable for the formation of nanorods. However, a novel change in these structures was observed when the concentration of the surfactant (oleic acid) was reduced and we obtained 2- D nanosheets. Fourier- transform infrared (FTIR) spectroscopy was utilized to confirm that the samples were made up of CdQ2. UV/ VIS spectroscopy was used to determine the different electronic transitions in CdQ2 molecule. All the samples possessed excellent photoluminescence (PL) properties. Photoluminescence (PL) spectra showed a prominent peak around 500 nm which indicated a strong PL emission in the green region. This methodology could be extended for the controlled, large- scale preparation of other functional complexes, and the obtained nanostructures could be introduced as the basic building blocks for novel optoelectronic devices.