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Evaluation of antifungal and phytochemical activity from different parts of cerbera odollam gaertn
No full textMaster of Science in Bioprocess EngineeringHeavy usage of commercial fungicide in the agricultural sector has resulted in
environmental pollution that has imposed a significant risk to human health. The current
research intended to explore the use of plant extracts (botanical) as alternative to
synthetic fungicide. Ethanolic extracts of Cerbera odollam from leaf, flower, fruit, seed,
wood and bark were tested for antifungal properties. Antifungal bioassay was
performed through dilution method at various concentrations (500 ppm to 3000 ppm)
against fungi: Aspergillus niger, Fusarium oxysporum and Penicilium citrinum and
assessed based on the Minimum Inhibitory Concentration (MIC). Plant toxicity was
tested by Brine Shrimp Test (BST) at different concentrations (5 to 1280 ppm).
Phytochemical tests were done using standard procedures to identify the phytochemical
compounds involved in the antifungal activity and Liquid Chromatography Mass
Spectrometry (LCMS) was performed to determine possible antifungal compounds
existed in all extracts. The results of the research showed that the inhibition zone for the
tested fungi generally exhibited antifungal activity from different parts. Among the
treatments, leaf extracts had recorded significant antifungal effects (P ≤ 0.05) against
Aspergillus niger and Fusarium oxysporum at all concentrations (500 to 3000 ppm)
with 3000 ppm showing the best inhibition zone. However, there was no significant
difference when extracts were tested against Penicilium citrinum. For the MIC study,
the lowest dosage recorded for leaf and bark was 250 ppm against Aspergillus niger,
while seed, fruit flower and wood showed the effect at 500 ppm; Penicilium citrinum
and Fusarium oxysporum recorded MIC value at 500 ppm from all treatments. In
toxicology test, the safe value is an amount over 20 ppm while 2 ppm and below is
considered unsafe or toxic for human being. Wood (5619.97 ppm), fruit (2116.66 ppm),
bark (1745.04 ppm) and flower (64.47 ppm) extracts showed safe levels while leaf (8.31
ppm) and seed (3.62 ppm) were slightly toxic and should be used with caution. LCMS
study of Cerbera odollam’s flower and fruit crude extracts were first reported in the
research. Antifungal compounds detected were neriifolin, hydroxybenzoic acid,
cerberinic acid, salicylic acid and terephtalic acid. Neriifolin and hydroxybenzoic acid
were identified for the first time from fruit, flower and wood extracts and cerberinic
acid, salicylic acid and terephtalic acid from bark extracts. The results of current study
indicated that Cerbera odollam leaf extracts has a potential of being a biofungicide
Photovoltaic powered uninterrupted power supply based on PIC microcontroller
No full textDoctor of Philosophy in Computer EngineeringThis thesis presents the photovoltaic (PV) powered uninterrupted power supply (UPS)
system based on PIC microcontroller. The study of solar radiation is very important to
know its potential to develop the PV powered UPS system. The PV powered UPS
system should have a solar charger that can charge the battery fast, a change over of
transfer switch that fulfill the standard of IEC 62040-3 and an inverter that has a lowest
current total harmonic distortion (CTHD). For these reasons, the thesis objectives are to
analyze the solar radiation potential to develop PV powered UPS system, to design a
solar charger, a transfer switch and an inverter. The data of solar radiation are measured
at the Renewable Energy Excellence Centre (REEC) Station, Universiti Malaysia Perlis
in Kangar, Perlis, Northern Malaysia. The solar charger, transfer switch and inverter
are constructed by PIC microcontroller. The results show that the average monthly solar
radiation is 4824.81 Wh/m2. It is greater than 3000 Wh/m2 and indicates that the sky in
Perlis is clear and the solar radiation intensity is very high. It indicates that the solar
radiation in Perlis gives big potential for PV powered UPS system. The proposed solar
charger can flow the charging current up to 24 A. It is due to the current can be divided
in same value by the multiple current circuits. The proposed inverter technique is able to
change peak voltage angle of the AC three-level waveform from 200 to 180'. An AC
load applied to the PV powered inverter shows that the lowest CTHD is obtained when
the peak voltage angle is 134'. A comparative study of CTHD between the proposed
three level single phase PV inverter and the market three level inverters (2000 W power
inverter, 2000 W Charger 10A SUVPR Series DY 2000C and 1000 W Charger 10A
SUVPR Series DY 1000C) are conducted. The result shows that the CTHD of proposed
three level single phase PV inverter is lower than the CTHD of the market three level
inverters
Induction motor drive system performance under influence of voltage sags and interruptions
No full textDoctor of Philosophy in Electrical Systems EngineeringThis thesis presents performance of induction motor drive system under influence of
voltage sags and interruptions. The drive system consists of an induction motor and
adjustable speed drive (ASD) that connected in series. Its terminal is connected to
power supply through a contactor and a circuit breaker. Contactor, ASD and induction
motor have being recognized as sensitive equipment to voltage sags and interruptions.
Investigation was started by identifying characteristics of voltage sags. The
characteristics considered are magnitude and duration of voltage sags, point on wave of
sag initiation (POW), symmetrical and unsymmetrical, repetitive and multistage voltage
sags as well as non-sinusoidal voltage sags. The testing results of three different
contactors show that their performances are greatly influenced by magnitude, duration
and POW of sag initiation. Non-sinusoidal voltage sags did not have significant
influence. In general, the contactors’ sensitivity increased when the contactors were
subjected to deeper and longer voltage sags. The POW influence of sag initiation on
three contactors have kepekaan es almost similar against sag duration. Sensitivity of the
contactors to sag duration decreases for the voltage sags with POW close to 90o.
Influence of POW on the contactor was shown also in repetitive voltage sags. It tripped
is slower for first voltage sag with the POW close to 90o. Testing has been carried out
in various conditions on ASD such as symmetrical voltage sag (type A voltage sag),
unsymmetrical voltage sags (types B, C and D), non-sinusoidal voltage sag supply and
sinusoidal voltage sags with various speeds and rated loads. Rectifier diodes behaviour
to conduct current are influenced by sag magnitude and sag types. Ride through of the
ASD against voltage sags was greatly influenced by performance of the rectifier diodes.
Type A and type C voltage sags caused all rectifier diodes were reverse biased. These
two types of voltage sags caused the ASD to trip. Type A produced higher sensitivity
than type C to sag magnitude
Estimation of potential solar energy in MTI region (Malaysia, Thailand and Indonesia) based on linear, nonlinear and artificial neural network models
No full textMaster of Science in Computer EngineeringSolar radiation (SR) data offer information on the amount of the sun potential at a location on the earth during a specific time. These data are very important for designing sizing solar photovoltaic (PV) systems. Due to the high cost of installation
and fitting troubles, these barriers cause lack of data and make data availability difficult. Prediction models for solar radiation are the key solution to substitute these important data and cover the missing from it. Therefore, there is a demand to develop alternative ways of predicting these data. The zone of Malaysia, Thailand and Indonesia (MTI), which are part of southeast Asia (SEA), is a huge area Had no model can cover all regions but only individual models assigned to particular countries. On
the other hand, the zone (MTI) had practiced many types of modeling techniques for solar radiation prediction, with variation in its prediction attitude and results accuracy; hence, it is very important to implement a comparison between models in
order to find the most accurate one. Best prediction model according to accuracy,
need to be compared with other similar neighbor models within the same zone. This
study presents linear, non-linear models as MTI linear and MTI nonlinear
models in order to develop a standardization modeling technique in this zone and
Artificial neural network (ANN) models has been implemented also in the same
area to predict its global and diffuse solar radiation. The different models have
been tested in different areas. These areas a r e classified as zone, region and
globally. It is found that the zone and region models are accurate and could be
used to predict solar radiation, which is an interested achievement. Nevertheless,
global models have a high error percentage. The results showed that the ANN
models are accurate in comparison with the nonlinear and linear models in which
the mean absolute percentage error (MAPE) in calculating the solar energy in
Malaysia by the ANN model is 5.3%, while the MAPE for the MTI nonlinear and
linear models is 6.4%, 7.3% respectively. In addition, the root mean square error
(RMSE) shows the following promising results, 7.2% for ANN model and 8.1%,
8.5% for the MTI nonlinear and linear models respectively. Finally, the mean bias
error (MBE) comes up with these next results ANN model is -1.3%, the MTI
nonlinear model is -1.1% and MTI linear model is -1.1%
Closed-form solutions and stress analysis of stainless steel/aluminum hybrid joint
No full textMaster of Science in Mechanical EngineeringHybrid joints are a combination of adhesive bonding and mechanical fastening that are able to combine the advantages of both joint types. Today, hybrid joining is attractive in automotive applications as the technique can offer various benefits during manufacturing. A 3 mm thin plate of Aluminium A7075 and stainless steel 304 were used as the adherend material for experimental test and the adhesive used was high performance Araldite Epoxy adhesive. This research examines stainless steel/aluminium hybrid joints to be tested in two ways. First is by using ANSYS software application where it was employed to deal
with stress analysis of the adhesive bonding of hybrid dissimilar joints using the finite
element method. Hybrid dissimilar joint specimens were fabricated having five bond
thicknesses; t (i.e., 0.4 mm, 0.8 mm, 1.2 mm, 1.6 mm and 2.0 mm). The effect of bond
thickness was investigated by using the commercial finite element package in ANSYS.
Various thicknesses of adhesive give different values of maximum von Mises stress. It is
found that greater thickness results in higher maximum stress. Moreover, various
thicknesses of adhesive also result in different values of deformation. This shows that
more deformation occurs when the thickness of adhesive is increased. This analysis proves
that increasing adhesive thickness reduces the joint strength, mainly because stress
distribution is increased on adhesive surfaces. Before proceed to second approach,
comparison between experiment and ANSYS was done. The purpose for this comparison
is to prove that ANSYS analysis is similar with experiment and the result can be use. The
second approach is to formulate a new equation using MATLAB tools for analysis of
shear stress distribution along the bond line under effect of adherend thickness ratio and
adherend Young’s modulus ratio. The solution is formulated based on the analysis of
Paroissien Eric. The least stress intensities in the joint could be achieved with a suitable
ratio of thickness and Young’s modulus of adherends. Result from both method ANSYS
and analytical model were compared and the results were in agreement, which means that
the analytical model can be used at least for the configuration considered in this study
The effects of service quality, perceived value, satisfaction and trust on foreign patients' loyalty of medical tourism in Malaysia hospitals
No full textDoctor of Philosophy in MarketingMedical tourism is one of the fastest-growing tourism sectors in the world, thus significantly contributing to economic development in many countries. Previous studies have estimated that the worldwide medical-tourism industry generates nearly USD 60
billion per year, with a growth rate of about 20% annually. In Malaysia, the medical tourism industry is considered as one of the most important components of the economy because of its great prospects. Foreign patients are an important target market for medical tourism service hospitals. In Malaysia, medical tourism is facing a very competitive environment, specifically from Asian countries like Thailand and Singapore. Many studies have shown that maintaining foreign patients’ loyalty is a very challenging task for marketers nowadays. Therefore, the objective of this study is to investigate the moderated mediation effects of service quality on patients’ loyalty to medical tourism in Malaysia. Hence, this study examines the moderating effect of perceived value and trust.
Perceived value moderates the relationship between service quality and satisfaction,
whereas trust moderates the relationship between satisfaction and foreign patients’
loyalty. In addition, satisfaction is a mediator between service quality and foreign
patients’ loyalty. A quantitative approach was adopted, whereby 640 questionnaires were
distributed to foreign patients in Malaysia. Out of this number, 389 responses were finally
found usable for analysis, which shows a 60% response rate. Data were analysed using
Partial Least Squares-Structural Equation Modelling (PLS-SEM). Overall, the findings
show significant relationships between service quality and satisfaction and foreign
patients’ loyalty. Also, satisfaction is significantly related to foreign patients’ loyalty in
Malaysia. In addition, satisfaction mediates the relationship between service quality and
foreign patients’ loyalty. This study could contribute to knowledge on perceived value as
a moderator between service quality and satisfaction as well as trust as a moderating
variable between satisfaction and foreign patients’ loyalty to Malaysian medical tourism.
In addition, this study contributes to theory by validating the attributes of the Theory of
“Self-Regulation of Attitudes, Intentions and Behaviours” regarding patients s’ intention
to stay longer in order to create a solid relationship with Malaysian hospitals
Studies on the densification and grain growth mechanisms of Polycrystalline ceramic based on LaYO₃
No full textMaster of Science in Materials EngineeringLaYO₃ is a polycrystalline ceramic with the perovskite type oxide structure. LaYO₃ was prepared using solid state synthesis method. Initially, the sample was heated between 1200 °C to 1500 °C for 10 hours and slowly cooled in air. The existence of secondary phases that belongs to orthorhombic shows the polymorphism properties of LaYO₃. Pure phase monoclinic structure was successfully synthesized after heated at 1500 °C for 10 hours and rapidly cooled in liquid nitrogen. Then, the pure monoclinic LaYO₃ powder was pelletized using cold isostatic pressing and been fabricated by two-step sintering method. For the first-step sintering (T1), pellets were heated at 1300 °C for 1 minute and then quenched into liquid nitrogen. The pellets were then reheated at the relatively lower temperature between 1000 °C to 1250 °C and denoted as T2 for 15 hours holding time. By increasing T2, the relative density increased from ~87 % to ~95 %. Percentage of shrinkage also linearly increased within error. Microstructural
analysis shows homogenous microstructure. The grain size was directly proportional to the relative density. Cole-cole plot from complex impedance of sintered LaYO₃ shows one semicircle contribute to the bulk phenomenon responsible. The conductivity for
samples sintered between 1000 °C to 1200 °C were in the range of 2 to 3 × 10-5 S/cm and the activation energy is about ~0.4 eV. Meanwhile, sample sintered at 1250 °C shows high conductivity that is 8.41 × 10-3 S/cm with 1.4 eV because phenomenon
responsible in the sample have grain boundary effect. Therefore, increasing T2 temperature shows high ionic conductor with electrically insulative behaviour that contribute by larger formation of grain growth
A review of Zinc Oxide-Tin Oxide (ZnO-SnO2) nanocomposite for humidity sensors
No full textLink to publisher's homepage at http://ijneam.unimap.edu.my/This paper reviews the fabrication of zinc oxide-tin oxide (ZnO-SnO2) nanocomposite in
humidity sensors. ZnO and SnO2 each has a wide energy band gap, making them suitable for
producing high-quality humidity sensors. Also, ZnO and SnO2 are the ideal heterojunctions
with high sensitivity and thermal stability. When combined, ZnO-SnO2 nanocomposite is an
n-type semiconductor with high versatility in many applications, such as gas sensors,
lithium-ion batteries, and photocatalytic degradation. Besides, the nanostructure film of
ZnO-SnO2 is relatively easy to prepare and characterise while manipulating ZnO and SnO2
could enhance device performances. Thus, the nanostructure of ZnO-SnO2 would likely
measure the humidity sensing performance easily
The effect of seeding method on the growth of zinc oxide nanorods
Get PDFLink to publisher's homepage at http://ijneam.unimap.edu.my/The paper presents the investigation of the method of seeding process for the growth of zinc
oxide (ZnO) nanorods (NRs) on the glass substrate as an electron transport layer (ETL) for
solar cells. The ZnO NRs were grown by using the hydrothermal method. The seeding process
was done via average deposition of zinc crystallite on the glass surface, and the process was
compared between with and without spin coating technique. The effect of spin coating
parameters during seeding phase on the growth of ZnO nanorods was also investigated in
this study. It was found that the sample prepared using the unfiltered solution without spin
coating in the seeding phase exhibited the densest ZnO NRs layer with the highest absorption
coefficient and high crystallinity
Virtual fabrication of 14nm gate length n-Type double gate MOSFET
Get PDFLink to publisher's homepage at http://ijneam.unimap.edu.my/Due to Moore's law, it is that predicted the channel length of a metal-oxide-semiconductor
Field Effect Transistor (MOSFET) will tend to shrink from the submicron to the nanoscale
size. Thus, precision in the manufacturing process has become crucial. This study describes
the virtual fabrication as well as the electrical characteristics of a 14nm NMOS double gate
with a bilayer graphene/high-K/metal gate. In this device, Hafnium Dioxide (HfO2) is
employed as a high-k material, and Tungsten Silicide (WSix) is used as a metal gate. Several
Silvaco TCAD Tools, including ATHENA and ATLAS, were utilized in the fabrication and
simulation of the device, respectively. According to the simulation results, the optimal
threshold voltage (VTH), drive current (ION), and leakage current (IOFF) and subthreshold
slope (SS) values are 0.2059 V, 797.5650 μA/μm. 29.5794 nA/μm, and 89.1712x10-3 V
respectively. The findings of this research showed that the efficiency of this 14nm double gate
n-type MOSFET device is satisfactory because the threshold voltage and leakage current
parameters are in accordance with ITRS 2013, and that it may have been utilized as a utility
man in future modelling and optimization efforts