Pusat Pengajian Sains Fizik - Tesis

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    Characterization Of Sala Mango Quality Attributes Via Visible And Near Infrared Spectroscopy Techniques
    (2015-05)
    Yahaya, Ommi Kalsom Mardziah
    Fruits‟ growers and local agriculture authorities in general have increasingly realized the importance of acquiring fruits with high quality in order to satisfy the market demands, specifically the consumers. Therefore, quality evaluations of fresh fruits using optical technique through spectroscopy measurement have been developed to non-destructively assess and measure internal quality attributes of Sala mangoes. In this research, several approaches with different technique of measurements (i.e. reflectance and interactance) have been performed and their competences were compared using Jaz, QE 65000 and FieldSpec 3 spectrometers via visible and near infrared spectral as well as visible monochromatic measurement systems for measurement of firmness, soluble solid content (SSC) and acidity (pH). Judging from the prediction performance, MSC was found to be the best pre- processing technique prior to multiple linear regression (MLR) for firmness measurement using QE 65000 spectrometer via reflectance mode with a coefficient of determination (R 2 ) and root mean square error of prediction (RMSEP) at 0.857 and 1.005 kgf , respectively. For soluble solids content (SSC), SNV was found to be the best pre-processing technique with R 2 = 0.882 and RMSEP = 0.783˚Brix through measurement using QE 65000 spectrometer via interactance mode. For acidity (pH), D 1 was found to be the best pre-processing technique with R 2 = 0.879 and RMSEP = 0.13 pH through measurement using QE 65000 spectrometer via reflectance mode. The results also showed that the direct calibration transfer procedure has successfully implemented to predict the pH of intact Sala mango between similar and differently
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    Empirical Modelling And Experimental Investigation On Absorption Spectra Of Colloidal Metal Nanoparticles And Quantum Dots Suspended In Ionic Surrounding Media
    (2019-04)
    Mehrdel, Baharak
    This study investigates the influence of the nanoparticle size and refractive index of non - absorbent ionic surrounding media on the optical absorption spectra of noble metal nanoparticles ( Au, Ag ; excited emission) and semiconductor quantum dots ( CdSe/ZnS ; spontaneous emission) designed for sensing application. Numerous studies on experimental research have shown that, the optical absorption spectra of noble metal nanoparticles and quantum dots are strongly dependent on the nanoparticle size and refractive index of surrounding media, while weakly dependent on the refractive index of non - absorbent ionic surrounding media which gradually change from 1.33 to 1.34. However, there is still lack of information on the effect of identity of the surrounding media for noble metal nanoparticles and quantum dots as a function of particle size. To address this issue, the first derivative method was applied to simulated absorption spectra of Mie theory and experimental absorption spectra of nanoparticles to quantitatively evaluate the spectra resonance. To determine the influence of identity of ionic surrounding media on the measured optical spect ra for noble metal nanoparticles and semiconductor quantum dots, a series of experiments were performed using sodium chloride (NaCl), sodium hydroxide (NaOH), and phosphate buffered saline (PBS). Specifically, the Mie theory was employed, with minor modifi cation to the dielectric constant of metal nanoparticles (Lorentz - Drude size dependent) followed by the first derivative method treatment to analyse the optical absorption spectra. R esults from the first derivative method showed the theoretical
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    Radiation Shielding Parameters For Composite Particleboard Added Baso4 And Bi2o3 At Orthovoltage Energy Range
    (2025-07)
    Abdullah, Siti Nor Azizah
    Wood-based composites have gained attention as potential radiation shielding materials due to their lightweight nature, adaptability for property enhancement, and versatility across various applications. This research studies a new metal added composite particleboard as a lead equivalent material for radiation shielding.
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    Fabrication And Characterization Of Sb Doped Tio2 Nanoparticle Synthesized By Laser Assisted Chemical Bath Deposition On Porous Silicon For Uv Photodetection
    (2025-07)
    Yusuf, Shehu
    The effects of antimony (Sb)-doping concentration into titanium dioxide (TiO2) material, whereby the doping films deposited utilizing laser-assisted chemical bath deposition (LACBD) technique on porous silicon (PSi) substrates-based ultraviolet photodetectors (UV PDs), have been studied for the first time in this work. The obtained results revealed that the Sb doping concentrations significantly affected the morphological, topographical, structural, optical, and photodetection properties.
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    Eu/Mg-Doped Sodium Silica-Borate Glasses From Recycled Soda-Lime-Silica Glass For Low-Dose Radiation Dosimetry
    (2025-07)
    Ezra, Nabasu Seth
    This study synthesised a radiation dosimeter with soda-lime-silica (SLS) glass, which is typically thrown in landfills, where it takes a long time to break down. Using this glass waste helped prevent the build-up of glass waste. Additionally, this reduces the need for pure SiO2. Two sets of glasses were synthesised by melt-quenching, the conventional method, doped and co-doped with Eu2O3 and MgSO4 respectively with compositions (Eu2O3)x (Na2O)0.1 (B2O3)0.6 (SLS)0.3-x and (Eu2O3)0.01 (Na2O)0.1 (B2O3)0.6 (SLS)0.29-y (MgSO4)y where x = y = 0, 0.005, 0.01, 0.03, and 0.05 mol%.