Pusat Pengajian Sains Kajihayat - Tesis

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Paleolimnological Assessment Of Environmental Change In Bukit Merah Reservoir Perak, Malaysia
(2024-08)
Simeon, Adole Akogwu
The aim of this study was to reconstruct historical environmental changes in Bukit Merah Reservoir using geochemical and diatom proxies. Two sediment cores, BMRI and BMR2, were collected, sectioned at 1cm intervals, and analysed for 210Pb chronology, metal(loid)s (arsenic, cadmium, copper, lead, zinc, and iron), nutrient levels (total nitrogen, total organic carbon, and total phosphorus), along with diatom composition using standard methods. The CRS (constant rate of 210Pb supply) model dated the oldest sediments back to 1985 ± 34 years AD (22.5-24.5). Stratigraphic analysis of metal(loid) pollution fluxes revealed variations over time. In the 1980s, lower fluxes were observed for arsenic (As), copper (Cu), zinc (Zn), and iron (Fe) at 29 mg cm-2 yr-1, 3.0 mg cm-2 yr-1, 75 mg cm-2 yr-1, and 148 mg cm-2 yr-1, respectively, which indicated a reduced rate of deposition of these metals during this period. These values contrasted with higher fluxes in the 2000s: 43 mg cm-2 yr-1 for As, 9.0 mg cm-2 yr-1 for Cu, 120 mg cm-2 yr-1 for Zn, and 2003 mg cm-2 yr-1 for Fe. indicating a significant increase in the accumulation of these elements during this period. Lead (Pb) fluxes were minimal in the 1980s (33.0 mg cm-2 yr-1), peaked at 56.0 mg cm-2 yr-1 in the 1990s, while cadmium (Cd) exhibited a similar pattern with minimal flux in the 1980s (2.20 mg cm-2 yr-1) and peak flux in the 1990s (3.60 mg cm-2 yr-1). The depositional fluxes of nutrients displayed fluctuations over time as well. Total phosphorus (TP) flux was lowest between 1985-1990 (1.56 mg cm-2 yr-1) and highest between 2016 and 2018 (3.98 mg cm-2 yr-1).
The Efficacy Of Insect Growth Regulators On Tropical Bed Bugs, Cimex Hemipterus (Fabricus) And Its Microbial Fauna Using Pcr Based Culture Dependent And 16S Rrna
(2024-03)
Taibukahn, Nurhidayah
Bed bugs are ectoparasites that primarily feed on humans and secondarily on other warm-blooded organisms. Two widespread species with medical relevance are the common bed bugs, Cimex lectularius L. and the tropical bed bugs, Cimex hemipterus (F.). Novel insecticides formulation are highly demanded due to the difficulties in battling bed bugs. For total eradication, it is important to administer long-term treatment using chemical and non-chemical active ingredients since bed bugs are capable in modulating their resistance mechanisms. This research exploits the regulation of microbial endosymbiont between insecticides treated and untreated tropical bed bugs, Cimex hemipterus employing PCR based culture dependent and 16S rRNA metagenomic based culture independent analysis. Prior to this study, field strain fifth stage nymph and adult bed bugs collected from residential area around Penang Island were treated with five classes of insecticides comprised of manufactured brand chlorfluazuron, chlorfluazuron, pyriproxyfen, methoprene, tebufenozide and β-cyfluthrin + imidacloprid act as positive control. The treated insecticide poses different mode of action in which chitin synthesis inhibitor, juvenile hormone analogue, ecdysteroid receptor agonist and mixture of pyrethroid and neonicotinoids that were applied at four different concentrations (100, 500, 1000 and 10 000ppm). Among the insecticides classes, manufactured brand chlorfluazuron and β-cyfluthrin + imidacloprid demonstrated the prominent mortality performance within the two weeks xviii of surface contact bioassay compared to other insecticides which offers less than 50% of mortality percentage.
Bacterial Population Of Pteris Vittata With Potentials For Bioremediation Of Arsenic Rich Soils And Plant Growth Promotion
(2024-03)
Salisu, Muazu Aminu
In soil environments, certain bacteria can withstand arsenic-induced stress and play vital roles in agriculture as plant growth-promoting rhizobacteria (PGPR). The bacteria enhance plant growth and contribute to the bioremediation of toxic arsenic in soils. This process also involves a selected group of plants known as hyperaccumulators, such as Pteris vittata, which enhance the efficiency of arsenic removal from the soil. Various methods are being used to cleanse the environment from the adverse effects of arsenic pollutant, but most of these methods are not cost-effective and have very poor performance. Bioremediation is used as a practical approach to address pollution caused by arsenic. This study aims to determine the bacterial population of P. vittata with the potential for bioremediation of arsenic-rich soils and plant growth promotion. The 16S amplicon metagenomics analysis was employed to determine the composition, functions, and bacterial diversity of soils from arsenic-rich and natural mineral sites. Conventional methods were employed to isolate, screen, and identify bacteria potentials for plant growth promotion, arsenic and other metals tolerance, detoxification, and bioremediation abilities. The selected isolates were evaluated for their efficiency in mitigating the toxic effects of arsenic, plant growth promotion and enhancement of the hyperaccumulation ability of P. vittata under different arsenic stress condition.
Establishment Of Tissue Culture Planting Materials Of White Strawberry [Fragaria × Ananassa Var. Pearl White (Iroha-001)] For Indoor Fruit Farming With Led System
(2024-08)
Pang, Wei Quan
This research investigates the multiple effects of variations in light spectrum and melatonin supplementation on the growth, development and genetic stability of in vitro-cultured Japanese Pearl White strawberry plants [Fragaria × ananassa var. Pearl White (Iroha-001)]. The Pearl White strawberry is a rare and exquisite fruit known for its striking appearance and unique flavour profile. Its luscious white colour and sweet, floral taste make it a coveted delicacy among fruit enthusiasts and connoisseurs. The white strawberry was chosen as a model plant because it is a high-quality, difficult-to-grow plant. Due to their low fruit yield, precise light treatment and labour-intensive cultivation, they are in high demand and therefore an ideal fruit for research. The study uses a comprehensive approach combining physiological, histological, and molecular analyses to elucidate the intricate interactions between these factors and their impact on tissue culture-based propagation. Surface sterilisation with a 30% Clorox solution (protocol 1) proved to be the most effective protocol, ensuring a clean and contamination-free starting point for the experiment. Subsequent studies revealed that the optimal medium for inducing multiple shoots and promoting proliferation involved the use of a 2 μM TDZ supplement in the Murashige and Skoog (MS) medium and without the need of auxins during root induction. The rooted plants successfully acclimatised to the ex vitro conditions and bore healthy fruit within a period of three months.
Fabrication And Characterisation Of Graphene-Poly (3-Hydroxybutyrate-Co-4-Hydroxybutyrate) Bioactive Glass Composite For Potential Wound Healing
(2024-08)
Abd Rahim, Mohd Aiman Hakimi
Managing wounds clinically presents a notable challenge. It involves not only ensuring that the dressing provides necessary barrier and promotes healing but also requires consideration of patient compliance in term of comfort, functionality, and practicality. Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) is a bacterial derived biopolymer widely notable for its exceptional chemical, physical, and mechanical properties. P(3HB-co-4HB) is widely known to be biodegradable and highly biocompatible. However, P(3HB-co-4HB) copolymer has its limitation as it exhibits hydrophobic properties, thus restrict its potential in regenerative medicine. Improving materials can address specific limitations within polymer matrices, such as hydrophilicity, mechanical behaviour, and morphological structure as well as biocompatibility. In pursuit of this goal, bioactive glass and graphene were integrated into the scaffold to enhance the physicochemical characteristics of the P(3HB-co-4HB) copolymer. Bioactive glass (BG) is recognised for its ability to stimulate vascularisation and regulate anti-inflammatory molecules and growth factor upon the release of its ions, which on turn enhances the process of wound healing. Graphene is known to possess excellent electrical, mechanical, thermal, chemical properties, and high surface area. It was synthesised using the liquid-phase exfoliation technique, which is a dependable approach for obtaining high quality graphene and economically viable.

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