Fayyaz Hussain

A rapid and non-invasive bio-photonic technique to monitor the quality of onions

We present the use of swept source optical coherence tomography and spectral domain optical coherence tomography for imaging the skins and concentric tissue leaves of intact whole onion bulb as well as single leave. The normal and watery scaled (defective) onion’s outer leaves and whole bulb have been characterized by cross sectional imaging of internal defects. The method can be used as potential investigating technique for application of food quality check during long storage.

Theoretical investigations of half-metallic ferromagnetism in new Half–Heusler YCrSb and YMnSb alloys using first-principle calculations

Structural, electronic, and magnetic properties of new predicted half-Heusler YCrSb and YMnSb compounds within the ordered MgAgAs C1b-type structure are investigated by employing first-principal calculations based on density functional theory. Through the calculated total energies of three possible atomic placements, we find the most stable structures regarding YCrSb and YMnSb materials, where Y, Cr(Mn), and Sb atoms occupy the (0.5, 0.5, 0.5), (0.25, 0.25, 0.25), and (0, 0, 0) positions, respectively. Furthermore, structural properties are explored for the non-magnetic and ferromagnetic and anti-ferromagnetic states and it is found that both materials prefer ferromagnetic states. The electronic band structure shows that YCrSb has a direct band gap of 0.78 eV while YMnSb has an indirect band gap of 0.40 eV in the majority spin channel. Our findings show that YCrSb and YMnSb materials exhibit half-metallic characteristics at their optimized lattice constants of 6.67 A and 6.56 A, respectively. The half-metallicities associated with YCrSb and YMnSb are found to be robust under large in-plane strains which make them potential contenders for spintronic applications.

Synthesis and study of structural properties of Sn doped ZnO nanoparticles

Abstract Pure and Sn-doped ZnO nanostructures were synthesized by simple chemical solution method. In this method we used zinc nitrate and NaOH as precursors. Sn doping content in ZnO was taken with the ratio 0, 5, 10, 15 and 20 percent by weight. Physical properties of Sn-doped ZnO powder were studied by XRD analysis which revealed that Sn doping had a significant effect on crystalline quality, grain size, intensity, dislocation density and strain. The calculated average grain size of pure ZnO was 21 nm. The best crystalline structure was found for 0 wt.%, 5 wt.% and 10 wt.% Sn doping as observed by FESEM and XRD. However, higher Sn-doping (> 10 wt.%) degraded the crystallinity and the grain size of 27.67 nm to 17.76 nm. The structures observed in FESEM images of the samples surfaces were irregular and non-homogeneous. EDX depicted no extra peak of impurity and confirmed good quality of the samples.

Molecular dynamics simulation of nanoscale surface diffusion of heterogeneous adatoms clusters

Molecular dynamics simulation employing the embedded atom method potential is utilized to investigate nanoscale surface diffusion mechanisms of binary heterogeneous adatoms clusters at 300 K, 500 K, and 700 K. Surface diffusion of heterogeneous adatoms clusters can be vital for the binary island growth on the surface and can be useful for the formation of alloy-based thin film surface through atomic exchange process. The results of the diffusion process show that at 300 K, the diffusion of small adatoms clusters shows hopping, sliding, and shear motion; whereas for large adatoms clusters (hexamer and above), the diffusion is negligible. At 500 K, small adatoms clusters, i.e., dimer, show almost all possible diffusion mechanisms including the atomic exchange process; however no such exchange is observed for adatoms clusters greater than dimer. At 700 K, the exchange mechanism dominates for all types of clusters, where Zr adatoms show maximum tendency and Ag adatoms show minimum or no tendency toward the exchange process. Separation and recombination of one or more adatoms are also observed at 500 K and 700 K. The Ag adatoms also occupy pop-up positions over the adatoms clusters for short intervals. At 700 K, the vacancies are also generated in the vicinity of the adatoms cluster, vacancy formation, filling, and shifting can be observed from the results.

Molecular dynamics simulation of mechanical characteristics of CuZr bulk metallic glasses using uni-axial tensile loading technique

In the present study, a three-dimensional molecular dynamics simulation is performed to elaborate the mechanical strength of bulk metallic glasses (BMGs). The radial distribution function (RDF) is used to predict the structural disorder that appeared during the quenching provided for BMGs processing. The mechanical behavior is investigated using uniaxial tensile loading through stress–strain curves. It is observed that during tensile loading, the yield strength of Cu50Zr50 increases with the increase in the strain rate, and it quickly attains the maximum value. Soon after the sample fractures without entering into the plastic region. To elucidate the effects of component concentration, we design BMGs with the following three configurations: Cu25Zr75, Cu50Zr50 and Cu75Zr25. It is revealed from the results that samples with a lower Cu concentration have a higher degree of short-range ordering and lower yield strength, and vice versa. To analyze the significance of crystalline–amorphous interfaces, we designed four cylindrical core–shell nanorods with Cu cores and BMGs shells. It is observed that the mechanical strength of the core–shell nanorod is significantly higher compared to the pure BMGs nanorod.

ab intio study of points defects in 2D graphene layer

With a hexagonal (honeycomb) network of mono-layered carbon atoms, graphene has demonstrated outstanding electronic properties. This work describes the impact of deliberately introduced single, double and triple carbon vacancies in grapheme monolayer. In addition, these carbon vacancies were then substituted with gold atoms and their influence on the electronic properties of the two-dimensional (2D) graphene layers was investigated. In this regard, a first principle calculation was performed to examine electronic properties and formation energy of 2D graphene layer by applying density functional theory (DFT). Introduction of such defects appeared to increase the stability of the graphene sheet as confirmed by formation energy calculations. Moreover, decrease of formation energy was noticed to be significant with an increase in the number of defects. Band structure calculations described the shifting of localized states from valance to conduction bands which caused the transformation of semiconducting beha...

Hematological Complications and Rouleaux Formation of Blood Components (Leukocytes and Platelet Cells) and Parameters

This chapter has the detailed and depth knowledge about the hematological complications and Rouleaux formation of blood components (leukocytes and platelet cells) and parameters. The purpose of this chapter is to determine the changes in three parameters, i.e., cells count, shape of cells, and size of cells, prior and after addition of three analytes, i.e., sugar, sodium chloride, and pure water, for ten varying concentrations, i.e., from 0 to 450 mM, admixed in 2 ml blood for sugar [C6H12O6], 3 ml blood for sodium chloride [NaCl] and 4 ml blood for pure water. We have also discussed the effects of sugar, salt, and distilled water in comparison with the preexisting literature. This chapter also contains information’s about sample preparation; methodology of bright and dark field microscopy under transmission mode used for each blood cells and parameters, 2-D images of each phantom of each analyte for its normal sample and admixed sample, tables and graphs to express the variation in parameters relative to each phantom, results of each phantom and detailed discussions about changes in blood parameters and components mentioned above for each analyte.

An insight into the dopant selection for CeO 2 -based resistive-switching memory system: a DFT and experimental study

The aim of this study is to figure out better metal dopants for CeO2 for designing highly efficient non-volatile memory (NVM) devices. The present DFT work involves four different metals doped interstitially and substitutionally in CeO2 thin films. First principle calculations involve electron density of states (DOS) and partial density of states (PDOS), and isosurface charge densities are carried out within the plane-wave density functional theory using GGA and GGA + U approach by employing the Vienna ab initio simulation package VASP. Isosurface charge density plots confirmed that interstitial doping of Zr and Ti metals truly assists in generating conduction filaments (CFs), while substitutional doping of these metals cannot do so. Substitutional doping of W may contribute in generating CFs in CeO2 directly, but its interstitial doping improves conductivity of CeO2. However, Ni-dopant is capable of directly generating CFs both as substitutional and interstitial dopants in ceria. Such a capability of Ni appears acting as top electrode in Ni/CeO2/Pt memory devices, but its RS behavior is not so good. On inserting Zr layer to make Ni/Zr:CeO2/Pt memory stacks, Ni does not contribute in RS characteristics, but Zr plays a vital role in forming CFs by creating oxygen vacancies and forming ZrO2 interfacial layer. Therefore, Zr-doped devices exhibit high-resistance ratio of ~ 104 and good endurance as compared to undoped devices suitable for RRAM applications.

Density Functional Theory (DFT) Study of Novel 2D and 3D Materials

In the present study, the analysis of novel 2D and 3D materials based on density functional theory (DFT) has been demonstrated which has drawn much research attention because of their fascinating properties. ZnO, GaN, diamond, and phosphorene are the best popular materials of recent study. Firstly, the enhancement of ferromagnetism in GaN monolayer doped with copper has been depicted. The findings of this study represent the ferromagnetic character due to the doping of 6.25% (concentration) of nonmagnetic Cu and magnetic long-range coupling among Cu dopant in GaN 2D monolayer which has the value of magnetic moment of 2.0 μB per Cu atom. While for ZnO (2D) layer, the formation of Schottky contact and the interfacial transfer of charge between Cu substrate and ZnO layer has been focused. In 3D materials case, diamond has been the center of attention because of its reliability in the materials society that is why different metals are doped in diamond. By the analysis of electronic properties, the semiconductor behavior is observed when diamond is doped with Ta. The negative value of formation energy makes oxygen-doped diamond layer, a thermodynamically favorable.

Optical Coherence Tomography as Glucose Sensor in Blood

Optical coherence tomography is a modern imaging modality that can visualize the biological tissues on micron levels. This chapter describes the use of OCT technique for measuring glucose in liquid phantoms, whole blood (in vitro and in vivo) based on temporal dynamics of light scattering. Whole blood smears imaged with microscope reveal the effect of red blood cells deformation and aggregation with white light microscope for animal and human blood. We found the changes in the shape of individual cells from biconcave discs to spherical shapes and eventually the lysis of the cells at optimum concentration of glucose. The increase of glucose in blood causes the changes in diffusion coefficients and shapes of the erythrocytes of glucose in stagnant and flowing fluids. The relative contributions of these competing effects have been studied by examining the motion dynamics of deformable asymmetrical RBCs and non deformable symmetrical PMS as flowing scattering particles. These systematic studies are aimed at eventual in vivo tissue imaging scenarios with speckle-variance OCT to visualize normal and malignant blood microvasculature in three and two dimensions and to monitor the glucose levels in blood by analyzing the Brownian motion of the red blood cells.