Pusat Pengajian Sains Fizik - Tesis
Browse
Recent Submissions
- PublicationExploring The Synergy Of Template And Machine Learning Methods To Improve Photometric Redshifts(2024-10)Khalfan, Alshuaili Ishaq YahyaThis thesis explores the use of both template-based and machine learning methods to improve the accuracy of galaxy photometric redshift estimation. The first method involves using template fitting to model the spectral energy distribution of a galaxy and estimate its redshift. The second method uses machine learning algorithms to learn the relationship between a galaxy’s photometric properties and its redshift, based on a training set of spectroscopic redshift measurements. This thesis also aims to investigates the potential synergy between these two methods by combining them in various ways and comparing the results to those obtained using each method individually. ( Password P-SD0060/21(R )
- PublicationOptimisation Of Magat Gel Dosimeter Embedded With Methylene Blue And Zinc Oxide Nanoparticles For Radiotherapy Application(2024-10)Alasady, Ahmed Mohammed AbidThis study aims to develop an effective 3D verification system using MAGAT gel dosimeters embedded with methylene blue (MB) and zinc oxide nanoparticles (ZnO NPs) to enhance the reliability of dose verification in nasopharynx cancer treatment (NPC).
- PublicationStructure Characterization And Nonlinear Optical Properties Of Novel Chalcone Derivatives: Experimental And Computational Investigations(2024-11)Ramzi, Farah DianaEight fluoro methoxyphenyl chalcones derivatives (1-8) with varying substitution groups were synthesized by the claisen-schmidt condensation method and crystallized using slow evaporation techniques. The compounds were characterized using ftir and nmr, as well as the 3d structural determination by scxrd. Hirshfeld surface analysis revealed that crystal packing and molecular conformation were stabilized through hydrogen bonding, π–π stacking, and halogen interactions. The molecular properties were determined using mep and npa analyses. The linear and 3rd-order nonlinear optical properties were studied theoretically (using dft and tddft) and experimentally (using uv-vis spectrometer and z-scan technique). The theoretical studies indicate that the absorption peak of compounds 1–8 is mainly contributed by an electronic transition from the ground state to the second excited state (s0→s2), with an excitation energy ranging from 4.17 to 4.29 ev, and transition electric dipole moment of 2.763 to 2.885 a.U. The experimental studies determined the two-photon absorption (2pa) of all compounds is mainly attributed to their nonlinear absorption (nla) in the non-resonant laser regime, consistent with the trend of dynamic
- PublicationBiological Effects Of Different Mri Exposure On Single-Strand Dna Of Rabbits: An In Vivo Study(2024-10)Shaheen, Ramziyah MustafaModern magnetic resonance imaging (mri) systems rely on a combination of static magnetic fields (smf), gradient magnetic fields (gmf), and radiofrequency fields (rf). The potential impact of mri on dna remains a subject of debate, particularly regarding its safety. Additionally, gadolinium (gd) contrast agents, commonly used in mri, have been associated with adverse side effects such as nephrogenic systemic fibrosis. This in vivo study, conducted on 45 male rabbits, aimed to investigate the effect of different mri magnetic strengths and exposure durations on single-strand dna (ssdna). Furthermore, it explored the effects of gd and alternative contrast agents, such as magnesium chloride (mgcl₂) and zinc oxide nanoparticles (zno nps), on ssdna after mri exposure. The comet assay was used to assess dna single-strand breaks (ssb), measuring three parameters: tail length (tl), percentage of dna in the tail (% dna tail), and tail moment (tm). The study also examined hematological parameters, including white blood cells (wbc), red blood cells (rbc), hemoglobin (hb), platelets, and lymphocyte percentage (lymph%), following exposure to different mri strengths over varying durations, alongside an analysis of redox reactions.
- PublicationMenyusun Pengesan Sinar Gamma Yang Mempunyai Sambutan Berkadaran(1982-12)Achmad, AmirDitunjukkan di dalam tesis ini bahawa satu sistem pengesan foton, yang terdiri dari satu pembilang sintilasi biasa, kristal NaI(Tℓ), yang dihadapannya diletakkan beberapa turas dari bahan-bahan yang sesuai, kecekapannya dapat dibuat berubah dengan tenaga foton datang parapaksi, menurut sifat yang ditentukan terlebih dahulu. Perkara ini dapat diperolehi dengan menyusun suatu formulasi di mana dengan formulasi itu memungkinkan kita dapat menyepadankan kecekapan Ei. bagi sistem pembilang untuk foton-foton bertenaga Ei dengan kecekapan yang diinginkan yang ditentukan oleh satu fungsi sambutan R(Ei). Beberapa pembolehubah yang digunakan di dalam pemadanan tersebut ialah sifat alam dan tebal bahan turas berserta dengan sebahagian lamanya masa turas itu berada di dalam bim foton yang sedang kita kaji. Berdasarkan penentuan kuasadua terkecil dapatlah dicari nilai-nilai optimum parameter di atas.