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    INFLUENCE OF Mn SUBSTITUTION ON THE STRUCTURAL, ELECTRICAL AND MAGNETIC PROPERTIES OF Ni-Cu-Cd BULK FERRITES SINTERED FROM NANOCRYSTALLINE POWDER
    (DEPARTMENT OF SCIENCE AND HUMANITIES, 2023-03) ALI MAZLOBEE, MIA MD FAKHARUDDIN
    Maintaining nanoscale properties in a high-density bulk form of ferrite prepared from powdered nanoparticles is quite desirable in many high frequency applications. Various Ni0.5-xMnxCu0.2Cd0.3Fe2O4 (NMCCFO, x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) dense bulk ferrites were consolidated from nano-crystalline powders by the sol-gel auto-combustion technique. Commercially available different nitrate salts of the ingredients were mixed thoroughly in stoichiometric amount and were calcined at 700°C for 5 h. Pellet and toroid shaped samples prepared from each composition were sintered at 1200°C for 5 h. X-ray diffraction (XRD) was used to carry out the structural analyses. The XRD data confirm that all compositions are single phase spinel structure. The lattice constant increase with increasing Mn content which is a clear indication of Mn incorporation in spinel structure. The theoretical density and the bulk density decrease but the porosity increases with increasing Mn content. The Rietveld refinement method confirms the goodness of fit with refined XRD data of NMCCFO for different Mn content. Rietveld technique is also adopted to determine the cation distribution between tetrahedral and octahedral sites and shows that maximum migration of Fe ions from A to B-sites occurs for x = 0.2 of Mn content. The Maximum Entropy Map analysis reveals the variation of the electron density with increasing Mn content and the presence of strong covalent bonding. Field emission scanning electron microscopy (FE-SEM) is used to carry out the surface morphology analyses. The average grain sizes increases from 1 μm to 4 μm for all compositions except x = 0.5 of Mn content. Energy dispersive X-ray (EDX) findings confirm the absence of traceable impurities and presence of Ni, Mn, Cu, Cd, Fe, and O in the samples. The dielectric measurements as a function of frequency and compositions are carried out at room temperature in the frequency range 100 Hz to 100 MHz. The dielectric constant (ε / ) and the dielectric loss tangent (tan δ) remains high at low frequency but becomes independent of frequency at higher frequencies for all the compositions of NMCCFO. This phenomenon may be explained by the Maxwell–Wagner model. The ac conductivity (σac) is derived from the dielectric measurements and it increases with increasing of frequency for all the compositions of NMCCFO. Frequency dependence of real (M/ ) and imaginary (M//) parts of the electric modulus and real (Z / ) and imaginary (Z //) parts of the complex impedance for different composition are measured at room temperature. The Cole-Cole plots (M/ vs M//) of electric modulus exhibit a tendency of formation of a single semicircular arc for all compositions indicates the existence of single-phase nature of the materials as well as the improvement in conductivity. Also, the Cole-Cole plots (Z/ vs Z//) of complex impedance exhibit a tendency of formation of semicircles end in the high frequency region. It explains the dominancy of the grain boundary. The vibrating sample magnetometer (VSM) was used for magnetization measurement at room temperature. From the hysteresis loop, the saturation magnetisation (Ms), remanent magnetisation (Mr), coercivity (Hc), the ratio (R) of Mr and Ms, anisotropy constant (K1), and magnetisation magnetic moment (μB) are calculated. All the compositions show the nature of soft ferrite due to the small amount of remanence and coercivity. Theoretical law of approach to saturation (LAS) shows that the values for both the saturation magnetization (Ms) and anisotropy constant (K1) are lesser than the experimental value. Therefore, the unique combination of electric and magnetic properties like low dielectric loss tangent, high ac conductivity and soft ferrite like behavior make the NMCCFO materials suitable for manufacturing high frequency devices like Multilayer Ferrite Chips Inductor (MLFCI), phase shifters, switches, etc.
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    SYNTHESIS AND INVESTIGATION OF FeNi AND FeCo BINARY NANOALLOY
    (DEPARTMENT OF SCIENCE AND HUMANITIES, 2019-12) TANVEER, RUBAYET
    FexNi100-x and FexCo100-x (x = 20, 40 and 80) alloy nanoparticles (NPs) were synthesized by sonofragmentation process, a facile one-step technique to produce NPs directly from bulk powders. The structural properties were studied by using X-ray Diffraction (XRD). The XRD shows the crystalline structure of the alloy samples and the size of the crystallites were calculated 35 nm and 19.3 nm for Fe-Ni and Fe-Co respectively with significant amount of phase purity. The compositions of Ni, Fe and Co in the alloy are confirmed from energy dispersive spectroscopy (EDS). It also reveals that there is no unwanted element in the alloys. Scanning electron microscopy (SEM) reveals the aggregation or cluster of spherical NPs with wide size distribution from 20 to 50 nm for all compositions of nanoalloys. The vibrating sample magnetometer (VSM) illustrates the superparamagnetic behavior of the alloys. The saturation magnetization (Ms) is found to be 57, 66 and 105 emu/g for Fe20Ni80, Fe40Ni60 and Fe80Ni20 NPs alloys respectively. The values of Ms were found to be 107, 131, and 153 emu/g for Fe20Co80, Fe40Co60 and Fe80Co20 NPs alloys respectively. However, the coercivity (Hc) is observed 73, 64 and 57 Oe for Fe20Ni80, Fe40Ni60 and Fe80Ni20 respectively. The value of Hc is also observed 128, 113 and 72 Oe for Fe20Co80, Fe40Co60 and Fe80Co20 respectively. It can be noticed that with increasing Fe content magnetization increases whereas corercivity decreases. The increasing magnetization may be ascribed to the incorporation of higher magnetic moments into the compositions. Such compositional dependent nature shows an important approach to attain tunable magnetic properties of Fe-Ni and Fe-Co NPs for their many practical applications. Moreover, the synthesized high magnetization Fe-Ni and Fe-Co nanoalloy can be used for XV various potential applications, and also this simple and environment friendly technique can be extended to synthesize other nanostructures.
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    IDENTIFICATION OF ANTICANCER DRUG THROUGH STUDYING THE ACTIVATION MECHANISM OF CASPASE PROTEIN: AN IN SILICO APPROACH
    (DEPARTMENT OF SCIENCE AND HUMANITIES, 2018-12) KHAN, MD. ARIF
    Apoptosis, a process of programmed cell death controlled by a defined apoptotic pathway, plays an important role in the development of all multicellular organisms. Any alterations in apoptotic pathways have been implicated in Cancer, one of the most deadly diseases in the world and Bangladesh as well. The pathway of Apoptosis is executed with a cascade of sequential activation of initiator and effector caspases, a family of proteases found in Apoptotic pathways to induce Apoptosis during abnormal cell growth in the cell cycle. Due to limited number of successful inhibitors in the market as well as pharmacological constraints of designed and tested peptide and peptidomimetic inhibitors against Caspase protein, In this study, In Silico approach like Virtual Screening with Molecular Docking applied to identify potential lead compounds against Pro-Caspase 7, one of the effector proteins of Apoptotic signaling proteins and 1571 drug-like molecules downloaded from the Binding database and ZINC database and identified four potential lead compounds. Noncovalent interactions like hydrogen bond, halogen bond, hydrophobic interaction, electrostatic interaction are examined among all the identified potential lead compounds and Pro-Caspase 7 after Molecular Docking study. In addition, Molecular dynamics study conducted to test the feasibility of the identified compounds in biological systems and again checked Molecular Docking energy and binding interactions for the Pro- Caspase 7 protein. Molecular dynamics study significantly increased binding energies among Pro-Caspase 7 and the first and third potential lead compounds and that are -15.8 and -14.3 kcalmol−1 respectively. Pharmacoinformatics analysis predicts that all potential lead compounds are non-carcinogenic and nonmutagenic. And, hence considering Molecular Docking study, Molecular dynamics study and Pharmacoinformatics study, the identified four potential lead compounds can induce Pro-Caspase 7 to Caspase which leads to Apoptosis and ultimately works for Cancer treatment. Although this in silico study helps the researchers and pave the way for Anti-Cancer drug development, further wet lab assessment of these potential lead compounds has to be performed.