http://dspace.mist.ac.bd:8080/xmlui/handle/123456789/5 2026-04-25T23:05:46Z 2026-04-25T23:05:46Z ALI MAZLOBEE, MIA MD FAKHARUDDIN http://dspace.mist.ac.bd:8080/xmlui/handle/123456789/821 2024-06-11T04:43:41Z 2023-03-01T00:00:00Z

INFLUENCE OF Mn SUBSTITUTION ON THE STRUCTURAL, ELECTRICAL AND MAGNETIC PROPERTIES OF Ni-Cu-Cd BULK FERRITES SINTERED FROM NANOCRYSTALLINE POWDER 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. Alhamdulillah, I express my humble gratitude to Allah Rabbul A’lameen whose unceasing and everlasting blessings enabled me to complete the research and submit the thesis in time. I express my profound gratitude to my respected supervisor Major Md Mahabubar Rahman Shah, MPhil, PhD, Department of Science and Humanities (Physics Division), Military Institute of Science and Technology (MIST) for his constant advice, constructive criticism and inspiration during the whole period of present investigation. Moreover, I am owed to him for his additional caring and solving different administrative issues related to this experimental work. With deep respect and honor, I would like to express fervently my earnest gratitude and indebtedness to my respected thesis Co-supervisor Prof Dr Mohammad Belal Hossen, Physics Department of Chittagong University of Engineering and Technology (CUET) for rendering me opportunity to perform my research work with all-out support and invaluable guidance throughout this academic journey. He has educated me the execution of research methodology and taught how to present the work in a clear and simple way. I would also like to thank him for his friendship, empathy and mental support in different critical situations. I am deeply grateful to Colonel Md Shahinoor Alam, SPP, PEng, Head, Department of Science and Humanities, Military Institute of Science and Technology (MIST), for his cooperation and coordination at different stages of the work. His valuable suggestions, timely guidance and constructive criticisms are praise-worthy and valuable assets for my life. I am also extremely grateful to the MIST authorities for providing the necessary financial grant for the research. I would like to thank all the respected teachers of the Department of Science and Humanities, MIST and Department of Physics, CUET, special thanks to Captain M Ziaul Ahsan, PhD (Ex Head of the Department), Lieutenant Colonel Brajalal Sinha, PhD, Major Tahmina Rahman of MIST for their cooperation. My special thank goes to affectionate junior brother M. Faishal Mahmood, a PhD student at Department of Physics in CUET who was a copartner in Functional Nanomaterials Laboratory. I am also thankful to my respected mentor Colonel Eare Md Morshed Alam, MPhil, PhD for his consistent mental support. I also would like to convey my thanks to the employees of the department of Physics, CUET and MIST for their co-operation and help specially to Mr Sohel Rana. I would like to acknowledge the moral support and the sustained inspiration of my loving wife Farhana Rahman and affectionate son Fasih Ur Rahman along with all other members of my family. This dissertation would have never been possible without their love, affection, encouragement and sacrifices. Finally, I am extremely grateful to my blessed parents, siblings and uncles for their love, caring, sacrifices, and prayers for preparing and educating me for my future.

2023-03-01T00:00:00Z TANVEER, RUBAYET http://dspace.mist.ac.bd:8080/xmlui/handle/123456789/446 2019-04-16T08:07:18Z 2019-12-01T00:00:00Z

SYNTHESIS AND INVESTIGATION OF FeNi AND FeCo BINARY NANOALLOY 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. At first, I fervently express all of my admiration and devotion to the almighty ALLAH, the most beneficial who has enabled me to perform this research work and to submit this thesis. With much pleasure, I respectfully express my earnest gratitude to my honorable teacher and supervisor Major Brajalal Sinha, PhD, Department of Science and Humanities, Military Institute of Science and Technology (MIST) for his scholastic guidance, instructions, valuable advice, suggestions, relentless patience and continuous encouragement throughout my voyage of research. I express my profound gratitude to my honorable co-supervisor Professor Dr. Mohammed Abdul Basith, Department of Physics, Bangladesh University of Engineering and Technology (BUET), for his constant direction, constructive criticism and inspiration in pursuing the whole investigation of the present research. Words are always insufficient to express his working capacities and unending enthusiasm for scientific rigorousness for innovative investigations. This always becomes everlasting source of inspiration for his students. I would also like to express my humblest thanks to Dr. Sri Ramulu Torati, Research Professor, Department of Emerging Materials Science, DGIST, South Korea for providing me with experimental facilities to carry out XRD, FESEM, EDS and VSM measurements of my samples during this research. Next, I offer my gratefulness to Captain M Ziaul Ahsan (retired), BN, Ex-Head, Department of Science and Humanities and Wing Commander Md Nurul Huda, Head, Department of Science and Humanities, MIST for their kind permission to perform this work. I thank my respected teacher V Major Md. Mahabubar Rahman Shah, PhD for his constant help throughout the completion of the degree. I am also grateful to MIST authority for providing the financial grant for this research. I am also grateful to Mr. Galib Hashmi who is a PhD student in Department of EEE at University of Dhaka and also my undergrad project supervisor for his guidance, inspiration and encouragement. I wish to give special thanks to Arif Khan and Lieutenant Sonjibone Sudha, (ND), BN my fellow M.Phil. Researchers for their constant support. I also thank all the staffs of Physics lab for their constant help while conducting my experimental works. I am earnestly thankful to The World Academy of Sciences, Italy for supporting our work with Grant 14-024 RG/PHY/AS_I-UNESCO FR: 324028590. Finally, I would mention a very special gratefulness for the moral support and sustaining inspiration provided by my family members.

2019-12-01T00:00:00Z KHAN, MD. ARIF http://dspace.mist.ac.bd:8080/xmlui/handle/123456789/396 2019-01-14T04:39:40Z 2018-12-01T00:00:00Z

IDENTIFICATION OF ANTICANCER DRUG THROUGH STUDYING THE ACTIVATION MECHANISM OF CASPASE PROTEIN: AN IN SILICO APPROACH 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. On the accomplishment of the present study, I would like to take this opportunity to extend my deepest sense of gratitude and words of appreciation towards those, who helped me during the pursuit of study. I deem it a proud privilege and feel immense pleasure to acknowledge all those who are directly or indirectly involved. I am thankful to the most Gracious, Merciful and Almighty Allah who gave me the health, thoughts and opportunity to complete this work. Words are inadequate in the available lexicon to avouch the excellent guidance given by my supervisor Major Mohammad Neaz Morshed, PhD, Associate Professor, Department of Chemistry, Military Institute of Science and Technology (MIST). His words of encouragement, endless inspiration, extensive support, scholastic guidance, inertness patience, and excellent counsel helped me to complete the research and thesis paper as accurately as possible. His dedication to research, meticulous planning, consecutive counsel, and unreserved help served as a beacon light throughout the course of study, and completion of this manuscript and guiding through my whole research work. I would like to express my heartfelt gratitude to Mohammad A. Halim, PhD, CEO of The Red- Green Research Centre, for his dedication to research, words of encouragement, kind advice, mental support and for allowing me the lab facilities The Red-Green Research Centre. I am also thankful to Major Palash Kumar Sarker, PhD, Associate Professor, Department of Chemistry, MIST for his deep inspiration, teaching, guidance and meticulous research insight that made me a success to complete this research work. I convey my sincere gratitude to Cdr M Ziaul Ahsan, BN, Professor and Head, Science and Hum Department, MIST for his kind cooperation and support to during my M. Phil study and research.

2018-12-01T00:00:00Z