Effect of annealing treatment on the uniformity of CeO2/TiO2 bilayer resistive switching memory devices

M. Ismail,A.M. Rana,S.-U. Nisa,F. Hussain,M. Imran,K. Mahmood,I. Talib,E. Ahmed,D.H. Bao 한국물리학회 2017 Current Applied Physics Vol.17 No.10

Bilayer CeO2/TiO2 films with high-k dielectric property were prepared by rf magnetron sputtering technique at room temperature. Effect of annealing treatment on resistive switching (RS) properties of bilayer CeO2/TiO2 films in O2 ambient at different temperature in the range of 350e550 C was investigated. Our results revealed that the bilayer films had good interfacial property at 500 C and this annealing temperature is optimum for different RS characteristics. Results showed that bilayer CeO2/TiO2 film perform better uniformity and reliability in resistive switching at intermediate temperature (i.e. 450 C and 500 C) instead of low and high annealing temperature (i.e. 350 C and 550 C) at which it exhibits poor crystalline structure with more amorphous background. Less Gibbs free energy of TiO2 as compared to CeO2 results in an easier re-oxidation of the filament through the oxygen exchange with TaN electrode. However, the excellent endurance property (>2500 cycles), data retentions (105 s) and good cycle-to-cycle uniformity is observed only in 500 C annealed devices. The plots of cumulative probability, essential memory parameter, show a good distribution of Set/Reset voltage.

Enhancement of bioactivity and bioavailability of curcumin with chitosan based materials

Khalid Mahmood Zia,Kashif Mahmood,Mohammad Zuber,Zill-i-Huma Nazli,Saima Rehman,Fatima Zia 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.12

Curcumin (CUR) has been investigated for its poor accessibility to a site of action or absorption and rapid metabolism to cope with the limited medication and cure applications. This article reviews numerous approaches, such as encapsulated surfactant/polymeric micelles, liposomes, micro/nano-spheres, nano-suspensions/composites, nanocomplex, films, and hydrogels for effective transfer of CUR to target sites. Chitosan (CS), and chitosan derivatives have been found to enhance therapeutic efficacy of CUR. CS/modified-CS based alginate, cyclodextrin, starch, dextran sulfate, ZnO, phytosomes, and poly(butyl) cyanoacrylate drug delivery matrices improved bioavailability, prolonged drug loading and permeability, sustained release rate, improved solubility and stability (prevent metabolic degradation) of CUR, consequently promoting various clinical applications. CS based polysaccharide, protein, and metal oxide drug delivery nano formulations advantageously participated to improve biological activities of CUR. We have attempted to summarize these delivery approaches, and reviewed future trends/strategies to permit the introduction of CUR as practical therapeutic drug.

First principle study of vanadium doped ZnS: Structural, electronic, elastic, magnetic and optical properties using mBJ approximation

Q. Mahmood,G. Murtaza,R. Ahmad,T. Hussain,I.G. Will 한국물리학회 2016 Current Applied Physics Vol.16 No.3

The structural, electronic, magnetic, mechanical and optical properties of ternary Zn1xVxS (x ¼ 0.0, 0.25, 0.50, 0.75 and 1.0) ferromagnetic semiconductor alloys have been studied in the zinc blende (ZB) phase, by first principle approach. Density functional theory has been employed to calculate the fundamental properties of the alloys using full-potential linearized augmented plane-wave plus the local orbitals (FPLAPW þ Lo) method. In addition, the electronic and magnetic properties are investigated by the local spin density approximation coupled with the modified BeckeeJohnson exchange potential (mBJLDA). Structural analysis revealed that the structure of the three alloys Zn0.75V0.25S, Zn0.50V0.50S, and Zn0.25V0.75S are stable in the ferromagnetic phase. It is noted that the calculated lattice constant decreases, while the bulk modulus increases with the increase of V content. The density of states and spin polarized band structure investigation demonstrated the half-metallic ferromagnetic characteristics of the investigated alloys and are also used to determines ped exchange constants N0a and N0b, due to S (p) eV(3d) hybridization. These results reveal that magnetic moment of V dopant element reduced from its free space value of 3 mB, because the Zn and S sites acquire minor atomic magnetic moments. The energy band gap analysis show an increasing trend with V doping that makes our compound a suitable candidate for the fabrication of devices operating in the ultraviolet region. Moreover, the static dielectric constant, ε1 (u), and static refractive index, n (u), increases with V contents. The incorporation of V generates some new peaks in the energy regions of 0e2.83 eV and 4e10 eV. The substitution by V increases the intensity of the peaks, and a slight red shift has been observed in the absorption peak. The extinction coefficient k (u) and optical conductivity also follow a similar trend to that of the dielectric constants. These results give deep insight into the design of devices for optical and spintronics applications using V doped ZnS.

Adaptive outlier elimination in image registration using genetic programming

Lee, I.H.,Mahmood, M.T. Elsevier science 2017 Information sciences Vol.421 No.-

<P>In feature-based methods, outlier removal plays an important role in attaining a reasonable accuracy for image registration. In this paper, we propose a genetic programming (GP) based adaptive method for outlier removal. First, features are extracted through the scale invariant feature transform (SIFT) from the reference and sensed images which were initially matched using Euclidean distance. The classification of feature points into inliers and outliers is done in two stages. In the first stage, feature vectors are computed using various distance and angle information. Feature points are categorized into three groups; inliers, outliers and non-classified feature (NCF) points. In the second stage, a GP-based classifier is developed to classify NCF points into inliers and outliers. The GP-based function takes features as an input feature vector and provides a scalar output by combining features with arithmetic operations. Finally, registration is done by eliminating the outliers. The effectiveness of the proposed outlier removal method is analyzed through the classification and positional accuracy. The experimental results show a considerable improvement in the registration accuracy. (C) 2017 Elsevier Inc. All rights reserved.</P>

Preparation of Cu₂ZnSnS₄ thin films by using electrospray method: Experimental and modeling approach on film growth

Song, D.,Kim, W.,Mahmood, K.,Kang, H.W.,Park, S.B.,Park, S.,Han, J.I. Elsevier Sequoia 2013 JOURNAL OF ALLOYS AND COMPOUNDS Vol.567 No.-

Cu<SUB>2</SUB>ZnSnS<SUB>4</SUB> (CZTS) thin films were deposited on glass substrate by using an electrospray method and an annealing process for improving the crystallinity and the morphology of the prepared films was performed. To investigate the relationship between the volume of a droplet on the substrate and the area of the deposited film, a numerical study on the wetting properties was performed for the first time in electrospray research, so a mathematical model to predict the shape of the droplet on the substrate with respect to temperature was developed. According to the simulation results, the deposition area by the single droplet was accurately predicted compared with the experimental data. In addition to the numerical approach, the properties of the films were experimentally analyzed. Consequently, the film with the best crystallinity, was synthesized by 60min electrospraying deposition and followed by the annealing at 663K. This film showed an optical band gap of 1.55eV. Thus, both experimental and modeling analysis will suggest a new process to produce inorganic thin films.

Synthesis of Ag-Loaded TiO2 Electrospun Nanofibers for Photocatalytic Decolorization of Methylene Blue

M. Raffi,Zaira Batool,Mashkoor Ahmad,M. Zakria,Rana I. Shakoor,Muhammad Aslam Mirza,Arshad Mahmood 한국섬유공학회 2018 Fibers and polymers Vol.19 No.9

Titanium dioxide (TiO2) is one of the excellent photocatalysts used for degradation of environmetal pollutants. In this work, 2.5, 5.0 and 7.5 wt.% of silver (Ag)-loaded TiO2 nanofibers of mean size 52-134 nm were synthesized by electrospinning method. These electrospun nanofibers were calcined at 500 oC to enable the transformation of Rutile (R) phase to Anatase (A), elimination of reaction moieties from the TiO2 matrix and subsequently formation of Ag clusters. The effect of Ag loading on the morphology, crystal structure, phase transformation, and band gap of these electrospun nanofibers have been characterized by scannining electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), raman spectroscopy and UV-visible spectroscopy. These nanofibers exhibited a red-shift in the absorbance edge and a significant enhancement of light absorption in the wavelength range of 250-550 nm. These electrospun nanofibers were investigated for photodecomposition of methylene blue (MB), and photocatalytic decolorization rates were determined by pseudo-first-order equation. The rate constants for the pure and those of 2.5, 5.0, and 7.5 wt% Agloaded TiO2 nanofibers were computed to be 0.1439 min-1, 0.1608 min-1, 0.1876 min-1, and 0.2251 min-1 respectively.

Robustness analysis of fractional order PID for an electrical aerial platform

N. M. H. Norsahperi,S. Ahmad,S. F. Toha,I. A. Mahmood,N. H. H. Mohamad Hanif 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.11

This work was performed to objectively measure and assess the robustness and tracking performance of fractional order of proportional, integral and derivative (FOPID) controller as compared to the conventional PID control. In satellite research and development, the satellite undergoes numerous tests such as thermal, acoustic and vibration tests in the cleanroom environment. However, due to space limitation in the cleanroom and the sensitive components of the satellite, it requires vibration-free, smooth and precise motion when handling the satellite. In addition, measurement interference might occur due to cable routing during procedures or tasks performed by an operator. Unlike the previous work, the robustness analysis of FOPID controller was not systematically conducted. In this paper, the analysis took into account the actuator dynamics, and various tests were considered to measure the robustness of FOPID controller. The designed FOPID controller was implemented on the scissor-type lifting mechanism of motorized adjustable vertical platform (MAVeP) model, and its performance was compared with the traditional PID controller. A comprehensive verification using MATLAB and Solidworks was carried out to generate the model and conduct the analysis. Both controllers were initially tuned using Nichol-Ziegler technique, and the additional FOPID controller parameters was tuned using the Astrom-Hagglund method. From the simulation work, it was found that the FOPID controller’s tracking error was reduced between 10 % - 50 % for the disturbance rejection tests and reference to disturbance ratio (RDR) spectrum was higher as compared to PID. The analysis in this paper was predicted to be the main driver to implement FOPID controller in the complex system in the industry, especially for sensitive material handling and transportation such as satellite.

Density functional theory study of electronic, optical and transport properties of magnesium based MgY2Z4 (Z = S and Se) spinels

Maiza Zanib,N.A. Noor,M.A. Iqbal,I. Mahmood,Asif Mahmood,Shahid M. Ramay,Najib Y.A. Al-Garadi,Tariq Uzzaman 한국물리학회 2020 Current Applied Physics Vol.20 No.10

Magnesium based spinel chalcogenides MgY2Z4 (Z = S and Se) have recently become a focus of renewed research interest owing to their high magnesium mobility; making them potential candidates for Mg batteries. In addition, the existence of a >1 eV band gaps in MgY2Z4 compounds also make them interesting for opto-electronic device operating in the visible to UV range of electromagnetic spectrum. Our calculations indicate that the electronic properties computed using the mBJ-LDA + SOC are in good agreement with earlier DFT calculations. The optical properties of the two compounds are examined as a function of incident photon energy, which indicate that these materials can be utilized in optical devices operating in visible and UV region of electromagnetic spectrum. The transport properties are also computed using BoltzTrap code where the variation of electrical conductivity, thermal conductivity and Seebeck coefficient with chemical potential and temperature is examined.