Amiruddin Shaari

Electronic band structure and optical parameters of spinel SnMg 2O 4 by modified Becke - Johnson potential

The electronic band structure and optical parameters of SnMg2O4 are investigated by the first-principles technique based on a new potential approximation known as modified Becke—Johnson (mBJ). The direct band gap values by LDA, GGA and EV-GGA are underestimated significantly as compared to mBJ-GGA, which generally provides the results comparable to the experimental values. Similarly, the present band gap value (4.85 eV) using mBJ-GGA is greatly enhanced to the previous value by EV-GGA (2.823 eV). The optical parametric quantities (dielectric constant, index of refraction, reflectivity, optical conductivity and absorption coefficient) relying on the band structure are presented and examined. The first critical point (optical absorptions edge) in SnMg2O4 occurs at about 4.85 eV. A strong absorption region is observed, extending between 5.4 eV to 25.0 eV. For SnMg2O4, static dielectric constant e1(0), static refractive index n(0), and the magnitude of the coefficient of reflectivity at zero frequency R(0) are 2.296, 1.515 and 0.0419, respectively. The optoelectronic properties indicate that this material can be successfully used in optical devices.

Magnetic Properties of Polyvinyl Alcohol and Doxorubicine Loaded Iron Oxide Nanoparticles for Anticancer Drug Delivery Applications.

The current study emphasizes the synthesis of iron oxide nanoparticles (IONPs) and impact of hydrophilic polymer polyvinyl alcohol (PVA) coating concentration as well as anticancer drug doxorubicin (DOX) loading on saturation magnetization for target drug delivery applications. Iron oxide nanoparticles particles were synthesized by a reformed version of the co-precipitation method. The coating of polyvinyl alcohol along with doxorubicin loading was carried out by the physical immobilization method. X-ray diffraction confirmed the magnetite (Fe3O4) structure of particles that remained unchanged before and after polyvinyl alcohol coating and drug loading. Microstructure and morphological analysis was carried out by transmission electron microscopy revealing the formation of nanoparticles with an average size of 10 nm with slight variation after coating and drug loading. Transmission electron microscopy, energy dispersive, and Fourier transform infrared spectra further confirmed the conjugation of polymer and doxorubicin with iron oxide nanoparticles. The room temperature superparamagnetic behavior of polymer-coated and drug-loaded magnetite nanoparticles were studied by vibrating sample magnetometer. The variation in saturation magnetization after coating evaluated that a sufficient amount of polyvinyl alcohol would be 3 wt. % regarding the externally controlled movement of IONPs in blood under the influence of applied magnetic field for in-vivo target drug delivery.

Uptake and clearance analysis of Technetium 99m labelled iron oxide nanoparticles in a rabbit brain

Nanoparticles as solid colloidal particles are extensively studied and used as anticancer drug delivery agents because of their physical properties. This current research aims to prepare water base suspension of uncoated iron oxide nanoparticles and their biodistribution study to different organs, especially the brain, by using a single photon emission computed tomography gamma camera. The water-based suspension of iron oxide nanoparticles was synthesised by a reformed version of the co-precipitation method and labelled with Tc99m for intravenous injection. The nanoparticles were injected without surface modification. X-ray diffraction (XRD), energy dispersive spectrometry (EDS) and transmission electron microscope (TEM) techniques were used for characterisation. Peaks of XRD and EDS indicate that the particles are magnetite and exist in aqueous suspension. The average diameter of iron oxide nanoparticles without any surface coating determined by TEM is 10 nm. These particles are capable of evading the reticuloendothelial system and can cross the blood-brain barrier in the rabbit. The labelling efficiency of iron oxide nanoparticles labelled with Tc99m is 85%, which is good for the biodistribution study. The sufficient amount of iron oxide nanoparticles concentration in the brain as compared with the surrounding soft tissues and their long blood retention time indicates that the water-based suspension of iron oxide nanoparticles may be an option for drug delivery into the brain.

Effects of compensating the temperature coefficient of frequency with the acoustic reflector layers on the overall performance of solidly mounted resonators

HighlightsTemperature compensated solidly mounted resonators are designed and fabricated.The influence of material properties of the different reflector layers composing the device on the TCF is discussed in detail.TCF is measured in both shear and longitudinal wave mode of the resonant frequency.The affect of temperature compensation on overall performance of SMRs is measured. &NA; Thin film acoustic wave resonator based devices require compensation of temperature coefficient of frequency (TCF) in many applications. This work presents the design and fabrication of temperature compensated solidly mounted resonators (SMRs). The characteristics of each material of the layered structure have an effect on the device TCF but depending on the relative position with respect to the piezoelectric material in the stack. The influence of material properties of the different layers composing the device on the TCF is discussed in detail. TCF behavior simulation is done with Masons model and, to take into account the deterioration of overall performance due to the finite lateral size and shape of the resonator, we have used 2D and 3D finite element modelling of the resonators. The overall behavior of the device for external loads is predicted. SMRs are designed according to simulations and fabricated with different configurations to obtain TCF as near to zero as possible with an optimized response. Resonators are made by depositing Mo/AlN/Mo piezoelectric stacks on acoustic reflectors. As reflector materials, conductive W and insulating WOx films have been used as high acoustic impedance materials. SiO2 films are used as low acoustic impedance material.

DFT investigations of structural and electronic properties of gallium arsenide (GaAs)

First principles calculations for structural and electronic properties of GaAs have been reported using a full potential linearized augmented plane wave (FP-LAPW) scheme of calculations developed within density functional theory (DFT). We use in this study local density approximation (LDA), Perdew-Burke-Ernzerhof parameterized generalized gradient approximation (PBE-GGA), Wu-Cohen parameterized GGA (WC-GGA) executed in WIEN2k code. In addition, to calculate band structure with high accuracy we used modified Becke-Johnson exchange potential (MBJ) + LDA approach. Our calculated lattice constant with GGA-WC is in good agreement to experimental value than LDA and PBE-GGA. Whereas our calculations for the band structure show that MBJ+ LDA approach gives much better results for band gap value as compared to other exchange correlation approaches.