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Anti-diabetic and anti-lethargic effects of stichopus horrens extract in type 2 diabetes-induced sprague dawley male rats
(2025-01)
Vixuan, Eng
Diabetes mellitus is a chronic metabolic disorder, that is attributed to either insufficient insulin production by the pancreas or impaired response of body cells to insulin. Present medication like metformin has brought significant therapeutic effects in treating this disease but the side effects prompt the researchers to explore other alternative treatments especially natural products. This study aimed to investigate the potential of different sea cucumber samples of Stichopus horrens, differentiated by extraction methods, in reducing fasting blood glucose level, minimising fatigue condition, and restoring structure and function in organs of diabetic type 2-induced rats. Two extraction methods were utilised in this study, which are hydrolysis and high-pressure processing (HPP). The first extract of sea cucumber was subjected to hydrolysis only, while the second extract was exposed to HPP only. The last extract of sea cucumber was subjected to both hydrolysis and HPP. In the in-vitro assay, human umbilical vein endothelial cells (HUVECs) were exposed to three Stichopus horrens body wall samples, and a positive control, metformin with concentrations ranging from 6.25 to 4000 µg/mL in MTT assay to obtain starting dosage of treatments for animal study. The in-vivo study involved Sprague Dawley (SD) rats, which included the induction of high fat diet for five weeks, 110 mg/kg of nicotinamide injection, followed by 55 mg/kg of streptozotocin (STZ) into creating Type 2 diabetes mellitus (T2DM) rat model. Rats were randomly grouped into six groups; normal control (n=3), diabetic control (n=3), metformin-treated group (n=3), sea cucumber extract (hydrolysis only) (n=3), sea cucumber extract (HPP only) (n=3), and sea cucumber extract (HPP and hydrolysis) (n=4). The findings displayed a decreasing trend in cell viability with increasing sea cucumber concentration with ICS0 values of 3.771 ± 0.152 µg/mL in sea cucumber extract (hydrolysis only), 3.783 ± 0.063 µg/mL in sea cucumber extract (HPP only), and 4.006 ± 0.054 µg/mL in sea cucumber extract (HPP and hydrolysis) while metformin depicted an increasing trend of cell viability with ECS0 value of 4.931 ± 4.044 µg/mL. As a result, the starting dosage for animal study pertaining to different treatments is 150 mg/kg each. The findings depicted decreasing trend of blood glucose level after four weeks of treatments with 150 mg/kg sea cucumber samples and increased exercise tolerance in sea cucumber extract (HPP and hydrolysis) group with 150 mg/kg. Apart from that, sea cucumbers exhibited mild restoration in histological changes of liver, kidney, and pancreas. The short treatment duration of sea cucumber on diabetic rats might prove that sea cucumber is a promising candidate for the development of novel product in the future.
Optimal dispatching and flexible topology methods for urban power systems
(2024-01)
Su, Yi
This thesis aims to investigate the optimal operation of three forms of Urban Power Systems (UPSs) which will be co-existence in a long time. First of all, aiming at AC / DC hybrid distribution system, the thesis proposes a comprehensive optimal dispatching model with centralized two-stage dispatching framework, achieving a 25.9% reduction in power loss compared to the initial model and increasing the integration of renewable distributed generations from 71% to 200%. Secondly, aiming at AC / DC hybrid active distribution system, the thesis incorporates social behaviours of electric vehicles and power demand response within a three-stage energy management framework, leading to a 13.07% enhancement in social welfare and a 19.90% increase in calculation speed. At last, aiming at transmission and distribution coupling system, the thesis proposes a two-layer optimal dispatching framework that takes into account the switching sequence along with dynamic thermal rating, leading to the effective resolution of congestion issues across various scenarios while maintaining a safety margin. In general, the models and optimization dispatching framework proposed in this thesis can help achieve the optimal power flow for UPSs, and improve its economic, security, and stable operation.
Numerical study of heat transfer and flow characteristics of microchannel heat sink with staggered water droplet geometries using water and nanofluids
(2024-02)
Soo, Yan Hao
The rapid transition of electronic devices from low performing, low-speed systems to high performance systems with high computational speeds has led to the exponential hike in power density which poses a challenge for effective heat dissipation. To prevent thermal-induced damages in miniaturized electronic devices, the heat dissipation rate must be increased by incorporating heat exchangers with large surface area to volume ratio such as the microchannel heat sink (MCHS). This research sought to augment the thermohydraulic performance of a conventional MCHS using two different approaches: geometrical modification and flow parameter modification. Three-dimensional conjugate heat transfer analyses were conducted using state of the art computational fluid dynamics (CFD) software, ANSYS Fluent 2022, to assess the hydrothermal attributes of water and water-based nanofluids on an MCHS, employing staggered water-droplet geometries. The research focused on single phase laminar flow (Re<1000) through microchannels with hydraulic diameter (D_h) of 750 μm and aspect ratio of 1.5. The thermohydraulic performances of the MCHS were evaluated against different geometric parameters including groove aspect ratio, groove pitch, groove size, and geometry type. Apart from that, the impacts of the nanofluid properties (i.e., nanoparticle type and nanoparticle concentration) on the heat dissipation performance were also examined in the study. The geometrical modifications were found to induce a substantial enhancement in the thermal performance of the MCHS through the promotion of fluid mixing which intensified the thermal exchange between the solid and fluid domains. However, the pumping cost associated with such modifications were higher because of a higher pressure drop penalty. The employment of nanoparticles as fluid additives led to a substantial heat transfer increment, albeit with a higher pumping power requirement. With that being said, the implementation of nanofluids is preferable in comparison to plain water as the advantages greatly outweigh the disadvantages.
Chinese traffic sign detection and recognition based on lightweight you only look once (YOLO) models
(2024-08)
Song, Wei Zhen
Detecting and recognizing traffic signs is crucial for intelligent driving systems, providing essential real-time guidance to drivers. Challenges such as bad weather, lighting, and occlusions hinder traffic sign detection. Conventional algorithms struggle to balance accuracy and real-time performance, leading to the favouring of lightweight deep learning detection algorithms for their automatic feature extraction and low computational cost. This study is based on the classic YOLOv4-tiny and YOLOv5s object detection algorithms, proposing several improvement strategies aimed at developing a more robust model for detecting traffic signs. This research selects the Tsinghua-Tencent 100K (TT100K) dataset and the CSUST Chinese Traffic Sign Detection Benchmark (CCTSDB and CCTSDB2021) datasets for training and evaluating traffic sign detection algorithms. Enhancements include an improved lightweight Better Efficient Channel Attention (BECA) mechanism, an upgraded Dense Spatial Pyramid Pooling (Dense SPP) network, an extra detection head, and optimized anchor boxes. The improved TSR-YOLO model showed significant improvements in precision (96.62%), recall (79.73%), F-1 Score (87.37%), and mAP (92.72%) with a stable FPS of around 81. However, due to its complexity, it is unsuitable for embedded devices. Thus, the study developed Sign-YOLO, which has been improved by a Coordinate Attention (CA) module, a High Bidirectional Feature Pyramid Network (High-BiFPN), and the Better Ghost Module to reduce model size. Sign-YOLO was evaluated on the CCTSDB2021 and TT100K datasets, reducing parameters by 0.13M compared to YOLOv5s, achieving a good balance between accuracy and speed for traffic sign detection.
Equatorial ionization anomaly characteristics over Malaysian region integrated by ground and satellite data
(2024-07)
Sivanandini a/p Selvakone
Equatorial ionization anomaly (EIA) is formed when both electric and magnetic fields intersect over the equator, resulting in electron density variabilities. The ionospheric irregularities disrupt radio communications and satellite operations by causing amplitude and phase scintillations of signals. Hence, the characteristics of the electromagnetic field and EIA must be studied simultaneously to understand the role of electromagnetic field variations on the EIA variabilities. Understanding these characteristics is important to mitigate the effects of the equatorial ionization anomalies on telecommunication and navigation systems. This study explores the periodic variations of electric and magnetic field intensities and their influence on the strength and development of EIA over the Malaysian region. Ground-based magnetometers from MAGDAS and INTERMAGNET systems, along with Swarm satellite data, are utilized for this synergistic analysis. The characteristics of EIA are studied for solar maximum and minimum years of 2015 and 2020, respectively. The investigation revealed diurnal and spatial variations in the EIA’s characteristics highlighting the influence of solar irradiance, space weather, and ionospheric dynamics. Notably, the EIA intensity, as indicated by geomagnetic variations, EEJ, drift velocity, plasma density, and temperature recorded by both sources was 36% higher in 2015 compared to 2020. This integrated approach enhances the understanding of the equatorial ionospheric phenomena and advances the accuracy of ionospheric forecasting models and predictions.

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Growth Of Single-Walled Carbon Nanotubes Through Pengethanol Colloidal Solution
(2011-10)
Seah, Choon Ming
Since the discovery of carbon nanotubes (CNTs), powder form catalyst support becomes the dominant in this field. But powder form catalyst support possesses some shortcoming such as difficulty in catalyst size monitoring and required subsequent purification. In this study, CNTs were grown over iron nanoparticles prepared by spin coated iron nitrate that diluted in colloidal solution of absolute ethanol and polyethylene glycol (PEG). The colloidal solution was later spin coated on silicon wafer and through catalytic chemical vapor deposition (CCVD) to grow CNTs. This approach competently overcomes the shortcomings aforementioned. In order to understand the effects of various process parameters on the topography of iron nanoparticles obtained and morphology of the as-grown CNTs, all the process parameters were studied separately. The parametric study was done in three stages, representing colloidal solution (composition of colloidal solution and concentration of iron nitrate), spin coating (spin speed, angular acceleration and spin period) and CCVD (reaction temperature, methane partial pressure and reaction period) study. Iron nitrate with concentration of 40mmol/L diluted in colloidal solution at a ratio 1:1 (v/v) of absolute ethanol to PEG-400, spin coated on silicon wafer at 8000 rpm for 30 seconds and under angular acceleration of 300rpm/sec was the best parameter to distribute iron nanoparticles evenly and in small size. This catalyst sample could grow single-walled CNTs (SWCNTs) with the highest selectivity and uniformity in diameter. Piranha solution was found useful to render the hyrophobicity of silicon oxide by introducing –OH group on the wafer. The –OH group was found could form a weak bond with PEG, providing force to reduce the surface tension. This led to the formation of catalyst nanoparticles of more uniform distribution. In CCVD, the best operating parameter to growth SWCNTs with highest uniformity and selectivity was at 850ºC under methane partial pressure of 0.333atm for 30 minutes. All three parameters were crucial to synthesize SWCNTs with high selectivity and crystallinity. The ratio of pre-growth catalyst size to the SWCNTs diameter was 2.3, while the ratio decreased to 1.38 for post growth catalyst used for comparison. Bigger the average size of catalyst nanoparticle resulted CNTs with wider distribution of diameter and also higher the ratio between the average catalyst nanoprticles to CNTs diameter. Finally, the crystallographic structure of the catalyst was also demonstrated as well. The iron nanoparticle was found to be converted to iron carbide after the growth of CNTs. The crystal structure was uniform throughout the whole catalyst particles. The decomposition of carbon sources on the surface of the iron and the dissolved carbon might diffuse to the center of the catalyst to achieve supersaturation and started the nucleation of CNTs. This work has successfully demonstrated a simple, novel and cost effective route to synthesize SWCNTs with high quality.
Equivalent diagonal strut coupled with hybrid plasticity approach for seismic response macro-modelling of clay brick wall infilled frames
(2020-11-01)
Van, Tze Che
Interaction between reinforced concrete frames and masonry infills under seismic load in Malaysia is often being overlooked by engineers and experts due to the low occurrence and magnitude of earthquake and scarcity of established research studies in the related area. Moreover, no guidance is given by Eurocode 6 and Eurocode 8 on macro-modelling approach of the seismic response of infilled frame. This study aims to provide an in-depth understanding on the seismic behaviour of masonry infilled reinforced concrete frames in Malaysia and to propose macro-modelling for masonry infilled frame through equivalent diagonal strut coupled with hybrid plasticity approach. Under the experimental testing, six half scale single-storey single-bay reinforced concrete frames with and without unreinforced clay brick infills were subjected to lateral monotonic and cyclic loadings. The seismic behaviour of the frame system improved in terms of strength, initial stiffness, energy dissipation and also delay in cracks formation in frame due to the presence of infill. However, the adopted masonry wall system is considered strong, thus induces shear failure in columns. It is discovered that effect of aspect ratio of infilled frame is significant in energy dissipation. Macro-Modelling of masonry infilled reinforced concrete frames using equivalent diagonal strut coupled with hybrid plasticity approach and an improved constitutive backbone law shows good correspondence with experimental result. Under the investigation of reliability of seven equivalent diagonal strut width models using the improved constitutive backbone law, it is discovered that models with similar strut width trends over aspect ratio produce similar responses. All the strut models are able to produce response with reasonable accuracy except Mainstone (1974) model. Seismic performance of a five-storey non-ductile masonry infilled reinforced concrete frames typically found in Malaysia was assessed using incremental dynamic analysis (IDA) with ten ground motion records. The collapse capacity at 16%, 50% and 84% fractiles of IDA curves are 1.0, 1.53 and 2.03, respectively. The maximum drift ratio where dynamic instability is reached ranges between 0.1% to 0.26%. This study has provided a practical elucidation of the interaction between infill and frame for the development of more realistic seismic-resistant design for Malaysia.
The Effects Of Bacillus And Lactobacillus As Probiotics On Mud Crab Scylla Paramamosain (Estampador, 1949) Zoea Larval Culture Performance
(Universiti Sains Malaysia, 2016-03)
Kwong, Kok Onn
Mud crabs (Scylla spp.) are commercially important crustaceans. One of the major obstacles to the growth of Scylla aquaculture is the low supply of hatchery produced seed due to bacterial diseases and high rates of mortalities. Currently, antibiotics are used extensively in Scylla larval culture to improve survival, but its use poses numerous risks including the development of resistance in bacteria to antibiotics, higher levels of virulence, and detection of restricted chemicals in the flesh of farmed animals. The aim of this study was to determine the culture performance of Scylla paramamosain larvae with the use of three different types of probiotics, namely a multispecies Bacillus, Lactobacillus casei (Shirota), and Lactobacillus plantarum, at various concentrations. There were higher average larval survivals in treatments with a multispecies Bacillus probiotics added compared with the control, especially at concentrations of 5.00 × 108 (12.33 - 18.33 ± 1.76 - 3.76 % compared to 1.67 - 3.67 ± 1.67 - 1.76 %; P < 0.05) and 1.00 × 109 cfu/ml. The best concentration of the multispecies Bacillus probiotic that gave lower Vibrio parahaemolyticus counts in this study was at a concentration of 1.00 × 109 cfu/ml. This was significantly lower than the control (1.33 ± 1.33 cfu/ml compared to 32.67 ± 11.05 cfu/ml) during the later days post hatching (DPH). Vibrio parahaemolyticus is known to be pathogenic to Scylla larvae, thus lower numbers are desirable in culture. On average, there were no obvious differences in water qualities and Larval Stage Indexes (LSIs) between the multispecies Bacillus treatments and controls, although larvae appeared healthier in the multispecies Bacillus treatments. Water qualities were within tolerable ranges for Scylla larvae. The fastest larval developmental stage was seen in the multispecies Bacillus treatment at 1.00 × 109 cfu/ml. Lactobacillus casei treatments at concentrations of 1.88 × 108 and 3.75 × 108 cfu/ml gave significantly higher survival rates compared to the control during the early to mid DPHs (49.70 - 99.30 ± 11.90 - 29.20 and 70.70 ± 13.03 % compared to 2.30 - 5.70 ± 1.20 - 5.70 %, respectively; P = 0.022 and 0.029). There were significantly higher survival rates in the Lactobacillus plantarum treatments compared to the control during the early DPH (74.33 - 90.67 ± 7.26 - 6.57 % compared to 47.67 ± 2.19 %; P = 0.040 and 0.005), at concentrations of 1.00 × 102 and 5.00 × 102 cfu/ml in the culture water. In terms of water qualities and LSIs, there were no obvious differences between the Lactobacillus treatments and controls, and this could be due to the relatively low concentration of Lactobacillus added. Based on the concentrations used in this study, the multispecies Bacillus probiotic was more effective than single species Lactobacillus for improving the survival rate and lowering V. parahaemolyticus counts of S. paramamosain larvae. The recommended concentration of the multispecies Bacillus to be added into S. paramamosain larvae was therefore 5.00 × 108 and 1.00 × 109 cfu/ml, and for Lactobacillus it was 3.75 × 108 cfu/ml. The use of Bacillus and Lactobacillus as probiotics is an ideal alternative to antibiotics in Scylla hatcheries to provide a consistent, commercially feasible production of seedlings.
Impact Of Traditional Prognostic Factor And Chemotherapy Schedule Modification On Breast Cancer Patients: A 5 Year Retrospective Study In A District Specialist Hospital In The State Of Perak
(Universiti Sains Malaysia, 2021-10)
Gobi Hariyanayagam A/l Gunasekaran
Chemotherapy schedule modifications are done in clinical practice due to treatment complications or the patients preference. Multiple clinical studies have established the negative prognostic impact of dose delay on survival rates. This study aims to investigate the prevalence and reason for chemotherapy schedule modification with the impact of schedule modification on the Overall Survival (OS) of the breast cancer patient. This retrospective cohort study was done among breast cancer patients receiving chemotherapy from 2013 to 2017 and was followed until 31 Dec 2018. Medical records of patients with cancer were reviewed. Inclusion criteria involved the female patients over eighteen years old, primary carcinoma of the breast, received Anthracycline or Taxane based chemotherapy regimen and completed more than two cycles of chemotherapy. Patients were categorised into three categories of no schedule modification, with schedule modification, and incomplete schedule. The Kaplan-Meier were used to test for survival differences in the univariate setting, and the Cox regression model was used in the multivariate setting. This study aims to measure the prevalence, OS rates, and Hazard Risk (HR) of these three treatment categories. Among 171 patients receiving chemotherapy, 28 (16.4%) had no schedule modification, 118 (69.0%) had schedule modification, and the remaining 25 (14.6%) had an incomplete schedule with OS of 75.0%, 59.3%, and 52.0%, respectively
Synthesis and properties of novel poly(alkyd-urethane)s derived from various types of vegetable oils
(2014)
Jem Shan, Ling
Triglyceride of oil palm (Elaeis guineensis), soy (Glycine max) and sunflower (Helianthus annuus) were used to produce novel alkyd diols and poly(alkydurethane) s with chemical structure specifically designed for better coating performances. The vegetable oils were first converted to monoglycerides by glycerolysis process. The monoglycerides derived from the different oils were reacted with phthalic anhydride at 2:1 monoglyceride-to-phthalic anhydride ratio to obtain novel polyols called alkyd diols. The polyols were then reacted with 4,4`- methylenediphenyldiisocyanate (MDI) to produce five novel poly(alkyd-urethane)s (PAU), namely palm oil based poly(alkyd-urethane) (POPAU), soy oil based poly(alkyd-urethane) (SOPAU), sunflower oil based poly(alkyd-urethane) (SFPAU), palm-soy oils based poly(alkyd-urethane) (POSOPAU) and palm-sunflower oils based poly(alkyd-urethane) (POSFPAU). The successful synthesis of the monoglycerides, alkyd diols and poly(alkyd-urethane)s were confirmed by FTIR, 1H NMR, 13C NMR spectroscopy and their morphology were evaluated by scanning electron microscopy (SEM). The obtained varieties of poly(alkyd-urethane) were applied onto substrates to study their physical and mechanical properties. Further analyses prior to application included viscosity, solubility, iodine number testing, gel content, drying time test while thermogravimetric analysis (TGA), crosshatch adhesion tests, impact strength, pencil hardness, chemical and water resistance were employed after the films were cured. The films showed good homogeneity and impressive thermal stability with palm oil poly(alkyd-urethane) showing only 5% weight loss temperature in N2 at 270oC. Overall, sunflower oil poly(alkyd-urethane) exhibited relatively better mechanical and thermal properties among all due to the highest percentage of cross linked fraction portrayed by its higher iodine value and gel content. Coating performance of poly(alkyd-urethane) based on palm oil was enhanced after blending with sunflower oil or soy oil based alkyd-diols. The adopted technique in the novel chemical design of poly(alkyd-urethane)s created a potential alternative reaction schemes to be applied in the industry for surface coating, binder for composites and other applications, aiding the effort to replace or minimize the use of non-sustainable petroleum-based raw material.