Browsing by Author "Dr. Kashif Tufail"

Filter results by typing the first few letters
Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    First Principle Study of Structural, Electronic and Magnetic Properties of Doped TbMnO3 for Transportation in Spintronic Devices
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2023) Sayyda Rimsha Irfan; CIIT/SP22-RPH-023/LHR; Dr. Kashif Tufail; LHR TP 8786
    Multiferroic Terbium Magnate, TbMnO3 (TMO), is one of the most investigated compounds for advances in spintronic devices. Single-phase multiferroic TMO can play an important role in the development of spintronics random access memory (RAM) due to its spin-polarized electronic, magnetic, and dielectric properties. However, the major challenge in the field of spintronic RAM technology is to generate a balanced magnetization of 25 MA/cm, more than 80% spin polarization at the Fermi level, and suitable dielectric constant in the range of 10 to 52. The present research work explores the structural, spin-polarized electronic, dielectric, and magnetic properties of Dysprosium (Dy) doped TMO structure for spintronic memory device application using first-principles calculations. The generalized gradient approximation (GGA) with Perdew-Burke Ernzerhof (PBE) is used to perform numerical simulation using CASTEP numerical coding. Dy impurities in TMO structure change the lattice constant, volume, and bond length, which profoundly affects the material's properties. The band gap in the spin-up and spin-down states is altered by the inclusion of Dy atoms due to increase in the energy states. The additional energy levels significantly enhance the spin polarization at the Fermi level, which is more favorable for spintronic devices. The addition of Dy-dopants as mono, di and triatomic in Pure TMO 2x2x2 super cell results in decrease in the magnetic moment. The half metallicity or 86.3 % spin polarization at the Fermi level, high dielectric constant of 1520.65, appropriate magnetism of 34.69 MA/cm has been observed for triatomic Dy doped TMO material in orthorhombic phase. Thus, triatomic Dy-doped TMO is a potential single-phase material spintronic ferro memory device applications.
  • No Thumbnail Available
    Item
    Novel Ce/Co Metal Organic Frame Work Based Opto-Electrochemical dual mode Sensor for Foodborne Mycotoxin Detection
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2025) Muhammad Mujeeb Ashraf; CIIT/FA23-RPH-027/LHR; Dr. Kashif Tufail; LHR TP 10001
    A novel cerium-cobalt metal-organic framework (Ce/Co-PTC-MOF) was designed and employed as a fluorescence quenching sensor for the fast and selective detection of Ochtratoxin A(OTA) in food sample based on Ce redox properties and dual oxidation state. The Ce/Co-PTC-MOF was characterized using X-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), photoluminescence (PL) spectroscopy, zeta potential measurements, and field emission scanning electron microscopy (FE-SEM) were employed for characterization. The MOF exhibited a hierarchical microstructure with a 3D flower-like morphology composed of ultrathin, interwoven nanosheets with strong negative surface charge. The fluorescence quenching response of Ce/Co-PTC-MOF was optimized by investigating the effects of MOF concentration, sonication time, incubation time, and pH on the quenching efficiency of Rhodamine B (Rh-B). The sensing mechanism was validated through fluorescence emission spectra, demonstrating efficient quenching of Rh-B by Ce/Co- PTC-MOF and significant fluorescence recovery upon the introduction of OTA. A machine learning (ML) approach was employed to enhance the sensor’s analytical capability by modeling the non-linear relationship between fluorescence recovery and OTA concentrations. The sensor exhibited a strong linear response to OTA concentrations ranging from 0.2 to 250 ng/L, with a low limit of detection of 10 pg/ml Electrochemical mode with electroactive surface area increased by nearly twice and electron-transfer kinetics increased at a moderately higher rate as compared to unmodified GCE, Ce/Co-PTC-MOF-modified glassy carbon electrodes (GCEs) generated electrochemical mode products. Surface blocking/passivation controlled the detection mechanism as OTA adsorption at Ce/Co site selectively reduced the difference pulse voltammetry (DPV) peak currents and augmented charge-transfer resistance (Rct) in electrochemical impedance statistica (EIS). The sensor worked on the principle of DPV with the sensitivity of 193.8 mAng-1mL +cm +2 and the detection limit was found as 0.1775 ng/mL, whereas the EIS gave a even lower result with a LOD of 0.20 ng/mL. The selectivity investigations showed the high specificity to the OTA as compared to other mycotoxins and in spiked food sample the maximum recoveries were 99.12 to 102.05 with a low relative standard deviation. According to the obtained results, the Ce/Co-PTC-MOF represents a high-potential multifunctional platform to detect OTA in food safely and without quality concerns with high sensitivity and selectivity as well as practicably, suitable in foods quality control
  • No Thumbnail Available
    Item
    On the Development of Non-enzymatic Sensor for Electrochemical Detection of Glucose
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2024) Aiman; CUI/SP23-RPH-014/LHR; Dr. Kashif Tufail; LHR TP 9635
    Glucose detection remains essential for food safety applications as well as environmental monitoring and medical diagnostics. Developing low-cost sensors that can detect glucose selectively in complicated environments while maintaining high sensitivity and reliability remains a current challenge. The research aims to develop an electrochemical sensor that combines high sensitivity and stability using graphene oxide material.Graphene oxide (GO) synthesis starts with a modified Hummers' method. A nitrogen-doped graphene oxide (NGO) material results from the sonication combination of GO with melamine. The sample material gets deposited on a pencil graphite electrode (PGE) before undergoing further modification through chronoamperometry to electrodeposit a Cu-Ni metal-organic framework (MOF) layer. The sequence of steps in this technique aims to improve both stability and electrocatalytic function of the sensor.Both electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) analyses verify that the sensor performs at an outstanding level. The sensor shows outstanding repeatability along with increased glucose sensitivity and powerful selectivity that remains unaffected by interfering substances. The sensor maintains consistent performance with different electrolyte conditions which makes it efficient and dependable for practical use.Furthermore, the Cu- Ni MOF-modified NGO electrode shown enhanced electrochemical properties by achieving notable improvements in diffusion-controlled electron transfer processes. A potential approach to glucose detection with excellent sensitivity, selectivity, and stability is provided by the proposed nanocomposite-based sensor