http://ir.library.sust.edu:8080/xmlui/handle/123456789/64 2026-05-08T06:26:53Z 2026-05-08T06:26:53Z Tarek, Sarfuddin Ahmed http://ir.library.sust.edu:8080/xmlui/handle/sust/244 2025-08-03T06:02:09Z 2023-07-01T00:00:00Z

INVESTIGATION OF NONLINEAR OPTICAL RESPONSES OF BOVINE SERUM ALBUMIN AND SOME AMINO ACIDS USING Z-SCAN TECHNIQUE Tarek, Sarfuddin Ahmed The Z-scan technique is a relatively simple but sensitive technique for studying third-order Nonlinear optical effects in materials. In this research work, we have implemented the continuous wave (CW) closed aperture (CA) Z-scan in conjunction with UV-Visible Spectroscopy for the optical characterization of Bovine serum albumin (BSA) and 13 of its constituent amino acids (AA). The Z-scan and UV-Vis spectroscopy are the two complementary optical techniques used for elucidating the interactions of electromagnetic radiations with studied materials at their molecular levels. Here, CW Z-scan has been employed to study third-order nonlinear refraction in terms of nonlinear optical (NLO) phase shifts (𝛥𝛷0) at 655 nm incident wavelength and at an optical power range of 74 mW to 106 mW, whereas the UV-Visible spectroscopy has been done in the 190 nm to 700 nm wavelengths to find the absorption by the molecules within this spectrum. The main objective of this study was to investigate variations in (𝛥𝛷0) of the amino acids with irradiances and at the same time investigate, whether there exists a relationship between the (𝛥𝛷0) of the Amino acids and that of BSA. To do that we have introduced a parameter called ‘Molar Phase shift Per unit power’ (𝜁𝑀) that is akin to the molar extinction coefficient (𝜀𝑚) used in the comparative study of UV- Visible absorbance. Also, these results are compared with a model that we have proposed herein. As a precursor to our experimental study, we have done an extensive review of the Z-scan covering the basics of the experimental method and its applications in the field of materials characterization, particularly in biomaterials research. The literature review provides a comprehensive overview of the CW Z-scan and the associated thermo-optic interaction affecting the refractive properties of materials. Additionally, our review work covers the historical background of research on amino acids, as well as nonlinear optical study using Z- scan technique. It has been observed that the amino acids with conjugated double bonds serve as active elements in both linear and nonlinear optical interactions. The materials and methods section describes instruments, materials, and step-by-step procedures followed in the preparation and handling of samples for UV-Visible spectroscopy and Z-scan experiments followed by the details of each experimental setup and instrumentation. ii The UV-Visible spectroscopy results for BSA and the amino acids have agreed well with previously published results. However, some previously unpublished details of methionine and lysine have been made. Furthermore, we have introduced revised model relating the molar extinction coefficient of BSA at 278 nm to the coefficients associated with constituent amino acids. This modification has resulted in significantly improved outcomes compared to previously reported values. Z-scans results of the samples have been compared in terms of their molar phase shifts per unit power (𝜁𝑀). It has been established that the nonlinear refraction in the CW regime is caused by multiphoton absorption. The data analysis and interpretation of results are presented, along with comparisons with previous studies and theoretical predictions. At the end of the analysis, we suggest extending this work to include other materials, wavelengths, and the time domain in the femtosecond regime to validate the observations made in this study. In summary, this doctoral thesis provides a comprehensive examination of the third-order nonlinear response exhibited by proteins and amino acids in the CW regime at 665 nm, which falls under the domain of optical spectroscopy. The findings of this study may contribute significantly to the advancements in the field of nonlinear optical spectroscopy. the degree of Doctor of Philosophy In Physics "INVESTIGATION OF NONLINEAR OPTICAL RESPONSES OF BOVINE SERUM ALBUMIN AND SOME AMINO ACIDS USING Z-SCAN TECHNIQUE."

2023-07-01T00:00:00Z Hossain, Md. Tarek Hossain http://ir.library.sust.edu:8080/xmlui/handle/sust/234 2025-07-27T05:34:37Z 2020-02-01T00:00:00Z

Wigner Rotation in Flat Space, Hyperbolic Space and the Outer Space of a Schwarzschild Black Hole Hossain, Md. Tarek Hossain We have represented Lorentz transformation and its consequences, i.e. time dilation and length contraction. The velocity addition formula has also explained. The formula of the transformation of orbital angular momentum and spin angular momentum has been derived. The numerical values of orbital angular momentum and spin angular momentum have been calculated. The orbital angular momentum versus light velocities and spin angular momentum versus light velocities have been plotted. We have introduced the Wigner rotation in two different ways. The formula of Wigner rotation has been derived in flat space in two different ways. The numerical values of Wigner rotation have been calculated for different cases. The graph of the Wigner rotation with respect to different velocities has been plotted. Rapidity is a hyperbolic angle that differentiates two frames of reference in relative motion. We have observed that the rapidity space provides a geometric approach to the Wigner rotation and the Thomas precession. We have also derived the formula of Wigner rotation in hyperbolic space. The numerical values of Wigner rotation in hyperbolic space have also been calculated. A graph of Wigner rotation versus boost angle for different boost velocities has been plotted. We have presented different types of Black holes such as Miniature Black hole, Stellar Black hole, Intermediate-mass Black hole, Supermassive Black hole, Schwarzschild Black hole, Kerr Black hole and Reissner- Nordstrom Black hole. We have derived the line element in Schwarzschild Black hole and the line elements of different Black holes have been represented. The formula of Wigner rotation in the outer space of Schwarzschild Black hole has been derived. We have also calculated the numerical values of Wigner rotation in the outer space of Schwarzschild Black hole. The graph of the Wigner rotation with respect to different velocities of a moving object has been plotted. A Dissertation Submitted for the Degree of Doctor of Philosophy “Wigner Rotation in Flat Space, Hyperbolic Space and the Outer Space of a Schwarzschild Black Hole”

2020-02-01T00:00:00Z Khan, Muhammad Alauddin http://ir.library.sust.edu:8080/xmlui/handle/sust/229 2025-07-24T05:42:52Z 2016-04-01T00:00:00Z

Spin Lattice order in frustrated Nickel- Zinc-Chromite (Ni x Zn 1-x Cr 2 O 4 ) System Khan, Muhammad Alauddin ZnCr 2 O 4 compound is well known to show the frustration of the spin structure. At 12 K, ZnCr 2 O 4 distorts to break symmetry of the degenerated frustrated spin states by the spin- Peierls-like phase transition, accompanying with the anti-ferromagnetic ordering. On the other hand, NiCr 2 O 4 undergoes a Jhan-Teller [JT] Phase transition at a temperature of 310K, differing from the low temperature ferromagnetic transition temperature T c of about 60K. It is also reported that NiCr 2 O 4 shows another magnetic phase transition at about 30K. These two phase transitions accompanying with the lattice change can be understood by the magneto-elastic interactions. Two interactions, the Jhan-Teller interaction and the spin-Peierls-like interaction co-exist in Ni x Zn 1-x Cr 2 O 4 system. In this report the Nickel-Zinc-Chromite [Ni x Zn 1-x Cr 2 O 4 ] compounds with x = 0.8, 0.6 and 1 are investigated by the X-ray diffraction measurements. From these measurements the Crystal structures are determined. The full width at half maximum [FWHM] and integrated intensity [I.I.] give the fruitful information for magnetic elastic interactions.The Phase transition of Nickel-Chromite [NiCr 2 O 4 ] at 30 K is not yet well understood. To investigate this phase transition, the magnetic moment of NiCr 2 O 4 and also the magnetic moment of other two components Ni 0.8 Zn 0.2 Cr 2 O 4 and Ni 0.6 Zn 0.4 Cr 2 O 4 were performed by Superconducting Quantum Mechanical Interference Device [SQUID]. From this measurement estimated effective Bohr magneton for NiCr 2 O 4 , Ni 0.8 Zn 0.2 Cr 2 O 4 and Ni 0.6 Zn 0.4 Cr 2 O 4 are 5.77, 6.34 and 7.84 respectively. The asymptotic Curie temperatures (θ CW ) are obtained as - 470 K, -565 K and -870 K. The corresponding frustration strengths are -7.2, -18.8 and -29.00. From the previous measurement when x = 0.5 and x = 0, the asymptotic Curie temperatures (θ CW ) were -498K and -380K and the corresponding frustration strengths were -30.18 and -31.00 respectively. Spin Lattice order in frustrated Nickel-Zinc-Chromite (NixZn1-xCr2O4) System, The requirement for the Degree of Doctor of Philosophy (Ph.D) in Physics

2016-04-01T00:00:00Z Rahman, A.K.M Azad http://ir.library.sust.edu:8080/xmlui/handle/sust/223 2025-07-22T04:46:15Z 2015-10-01T00:00:00Z

A study of quality of different kinds of bricks and other building materials available in Bangladesh using neutron radiography technique and design of a small scale neutron radiography facility Rahman, A.K.M Azad Manufacturing building materials has become very good option of business in the developing countries like Bangladesh. Quality control of these materials and environmental friendly structure assurance should be confirmed on approaching such industrial establishments. Among the non-destructive testing (NDT) techniques Neutron Radiography (NR) is the most common procedure to study internal structure, homogeneity, any inclusion or voids or cracks etc. The water penetration behaviour and structure can be identified more effectively through this NDT technique. Present study has been carried out to differentiate two types of brick manufacturing processes named Hoffman Kiln method and conventional local method. Thermal neutron radiography facility of 3 MW TRIGA Mark-II research reactor of Atomic Energy Research Establishment (AERE), Savar, Dhaka has been utilized in this research work. Densitometric measurements of the neutron radiographic images of the samples have been adopted in this work. The samples were collected from different places in Bangladesh depending on their manufacturing process including fuel to burn, burning process etc. At first the appropriate irradiation time was determined for the samples and then neutron radiographs were taken after drowning the samples up to 1 inch into water for 5 min, 10 min, 15 min and 20 min consecutively. The radiographic images under all these conditions for individual samples have been investigated and it can be concluded with the statement that bricks made of Hoffman Kiln method are more homogeneous inside, absorbs lower amount of water and most importantly products of this environmentally friendly system can construct better, safer and long lasting building structure for livelihood. In addition, the quality of some jute-plastic products and some special types of concretes used inside some buildings has also been studied. Finally a small neutron radiography facility has been designed which may be useful to study different types of building materials. A dissertation submitted for the degree of Doctor of Philosophy, “A study of quality of different kinds of bricks and other building materials available in Bangladesh using neutron radiography technique and design of a small scale neutron radiography facility."

2015-10-01T00:00:00Z