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The use of social media in mitigating social issues in Malaysia / Ali Fauzi Ahmad Khan
No full textThis research considers how social media may have fostered innovative technology use to mitigate societal issues. The article presents 3 cases. First, it shows how social media can help and hinder crime prevention efforts. Second, it examines social media use during a disaster. Third, it explains how social media can be used for social advocacy using the response to a ban on homeless people from city streets. Most social media research focuses on user behavior, organizational applications, and data mining. This research emphasizes users' perspectives. It uses structured pragmatic-situational (SPS) data collection and analysis to conduct case studies. The three cases involved sixty-six interviews totaling 100 hours. Follow-up interviews and document analysis revealed more user concerns and functions.The research findings were analyzed using the affordances and constraints theory in case one, the resource-based view theory in case two, and the "grassroots" or community organizing theory in case three. Each chapter presents findings based on relevant theories. For example, case one presents the affordances and constraints of social media in crime prevention. Case two suggests a process diagram of how social media was used during the disaster. Case three, using theory, describes how power appears to be shifting from authorities to society.It will contribute to social media research by developing a theory that explains how society uses social media to solve problems. Events with high social media usage will be analyzed using interviews and social media sites. The emergent theory will advance social media research. In addition, unknown issues will be introduced, contributing to social media research
Novice programmers’ emotion and competency assessments using machine learning on physiological data / Fatima Jannat
No full textThe technology of psycho-physiological measurement and Eye-tracking has opened up a
wide range of possibilities for automating the prediction of human emotional state for a
particular event. There is also growing interest in modeling machine learning and deep
learning algorithms that can learn from user’s data, understand and react to that individual’s
affective state. This research work has used novice programming learners’ eye-tracking
and Galvanic Skin Response (GSR) data in a novel approach. This work investigates
the suitability and effectiveness of machine learning algorithms such as Multinomial
Naive Bayes, KNN, Logistic Regression, Decision Tree for predicting levels of arousal
intensity among the programmers and LSTM deep learning algorithm to classify the
programmers according to their performance. Through experiments with the data-set, it
was found that Multinomial Naive Bayes outperformed other supervised machine learning
algorithms with 75.93% accuracy and 96.54% ROC while predicting levels of arousal
intensity. Hyper-parameter tuning has been used in all the algorithms using k-fold cross
validation to have the best accuracy and to avoid the over-fitting issue. The result implies a
good connection between how a novice programmer goes through a programming problem
and his/her emotional arousal at that moment. The Long Short-term Memory (LSTM)
deep learning model was chosen for classifying programming learners according to their
performance. LSTM model has the advantage of having internal memory suitable for
longer sequences like our Eye-tracking and GSR data sequence. The LSTM model resulted
in 65.71% test accuracy while classifying the students’ performance
First-principles study of two-dimensional Mg2C as an anode material for metal-ion batteries / Chu Yi Zhi
No full textOwing to their compelling physicochemical and structural properties, two-dimensional (2D) materials have recently emerged as potential candidates for various energy storage and electrochemistry applications. One of the energy storage applications is the anode material for lithium-ion batteries (LIBs). The ever-increasing demand for high-capacity LIBs anode material due to the rapid development of advanced portable electronic devices and electric vehicles have garnered attention on the newly emerged 2D materials as an anode material for LIBs and other metal-ion batteries. Recently, a newly discovered carbide based 2D materials, the 2D Mg2C has been reported to be exhibiting tunable metallicity. In the present study, first-principles calculations are carried out to investigate the performance of 2D Mg2C as anode materials for Li, Na, K and Ca-ions batteries. The structure of 2D Mg2C remained stable upon adsorption of the Li, Na, K, or Ca adatoms as suggested by the calculated binding energies. Encouragingly, the metallic behavior of the adsorbed Mg2C is desirable to enhance the electric conductivity of 2D Mg2C as anode materials. The diffusion barriers of the a atoms are calculated to study the diffusivity of the adatoms on the 2D Mg2C. It is shown that Na and K ad atoms exhibits extremely high diffusivity on the 2D Mg2C with a low energy barrier of 0.08 and 0.04 eV, respectively, which is beneficial for a fast charge/discharge process. The energy barrier for Li and Ca atoms are respectively 0.7 and 0.9 eV, which is about one order of magnitude higher than that of Na and K. Furthermore, for the Na and K atoms, the theoretical
Effect of gas flow rate and deposition pressure toward the crystallographic and surface morphology of semi-polar (112̅2) gallium nitride grown by MOCVD / Ooi Chong Seng
No full textV/III ratio and pressure is frequently varied to study the metalorganic chemical vapor deposition (MOCVD) growth parameters effect on semi-polar (112̅2) gallium nitride epitaxy (GaN) growth on m-plane (101̅0) sapphire substrate. In the first study, V/III ratio is fixed at 118 while varying the Trimethylgallium (TMG) (33.6, 59, 84.3 and 100 sccm) and ammonia (NH3) (0.4, 0.7, 1.0 and 1.3 SLM) flow rate, respectively. Varying gas flow rate implies different growth rate is induced. Different GaN film with different surface morphologies was produced and their crystal quality was determined. High-resolution Xray diffraction (HR-XRD) analysis shows that low gas flow enhanced the GaN crystal quality with lowest FWHM values of 576 and 1656 arcsecs at [11 ̅̅̅̅23] and [11̅00], respectively. Field-emission scanning electron microscope (FESEM) also verified that 2D GaN morphology is produced. Whereas high gas flow exhibits low crystal quality together with the distribution of 3D islands on the surface. Atomic force microscopy (AFM) micrographs show different arrowhead elongation length produced at a different flow rate. The presented results suggest that low gas flow rate with low growth rate is necessary to obtain a flat semi-polar (112̅2) GaN layer. In the second study, the first experiment is repeated by growing on AlN nucleation layer at fixed V/III ratio of 1300 with lower TMA and NH3 flow rate. There was not much difference in the HR-XRD analysis between the first and second series. The phase and the X-ray rocking curve (XRC) analysis consistently show that the crystal quality improved when TMG and NH3 gas flow rate is lowered. However, the FESEM results showed that there were less 3D islands formed compared to the first series when GaN grown on aluminum nitride (AlN) nucleation layer with lower gas flow rate. In contrast, the AFM analysis showed quite similar surface roughness with the first series when compared with each TMG gas flow rate, respectively. The third study involved the variation of reactor pressure (40, 70 and 100 kPa) on GaN epitaxial layer. It has been found out that highest reactor pressure of 100 kPa effectively reduced the dislocations and stacking faults with lowest FWHM value of 416 and 857 arcsecs at [11 ̅̅̅̅23] and [11̅00], respectively. However, higher growth pressure resulted in very rough surface morphology and larger surface grain size which led to 3D growth mode. The surface roughening mechanism for both gas flow rate and pressure variation are also explained using the adatom surface diffusion relatio
Robust volatility measures and multivariate models for volatilities and returns with financial applications / Tan Shay Kee
No full textVolatility of asset prices in the financial market is not directly observable. Various
return-based models have been proposed to estimate the volatility using daily closing prices.
With the availability of intraday information such as the opening, highest, lowest and
closing prices, many volatility measures were proposed to estimate the volatility directly.
This thesis aims to improve these volatility measures and further proposes advanced
volatility models to model these measures. We first apply Garman-Klass (GK) range-based
volatility measure to measure the volatilities of 102 active cryptocurrencies and models the
persistence and leverage features of the GK volatility measures using asymmetric bilinear
conditional autoregressive range (CARR) model. Focus on the top five cryptocurrencies,
we relate these features to their time of development and transaction speed. Since the
accuracy of the volatility measures may be distorted by the occurrence of extreme prices,
our second contribution proposes two unbiased quantile-based volatility measures, namely
quantile Parkinson (QPK) and quantile Rogers-Satchell (QRS) to measure daily volatilities
and shows how they can robustify the Parkinson (PK) and Rogers-Satchell (RS) measures
in the presence of intraday extreme prices. Scaling factors for different interquantile range
levels are provided to ensure the unbiasedness of QPK and QRS measures and simulation
studies are performed to confirm their efficiencies relative to intraday squared returns
(open-to-close) and their respective range-based volatility measures in the presence of
extreme prices. To smooth out the noises in these quantile-based measures, the CARR
model is fitted with different mean functions and error distributions as the first stage. The second stage imputes the best fitted volatilities into the return models to capture the
heteroskedasticity of returns. This two-stage model is called CARR-return model. Risk
measures such as value-at-risk (VaR) at different levels based on the return models are
evaluated and tested. Empirical examples are provided to demonstrate the applicability
of the proposed measures and the two-stage models. Our third contribution extends the
CARR-return models to a multivariate setting to forecast cross dependency of multiple
asset returns for portfolio risk assessments. Extensive comparisons are carried to evaluate
the modelling and forecasting performances with the multivariate CARR-return models
and multivariate GARCH models. Different levels of VaR based on the return models are
evaluated and tested to confirm the accuracy of the VaR forecasts
Spectroscopic studies on the chiral recognition of ketoprofen enantiomers using different selectors / Asma Omar Obaid
No full textKetoprofen is a chiral drug marketed as a racemic mixture for medicinal use. The
physiological reactions of R-ketoprofen and S-ketoprofen within the human body differ
considerably; therefore, enantiorecognition is a necessary process that can be done using
chiral selectors that interact differently with only one enantiomer. In this study, the
potential of different chiral selectors for recognizing ketoprofen enantiomers was
investigated. Gold and silver nanoparticles (AuNPs and AgNPs) were synthesized and
characterized then used for recognition of ketoprofen. AgNPs with ketoprofen
enantiomers showed significant differences in the appearance and spectra obtained, while
no differences were obtained between R- and S-ketoprofen when using AuNPs. Then
beta-cyclodextrin (β-CD) and hydroxypropyl-beta-cyclodextrin (HPβ-CD) inclusion
complexes with R- and S-ketoprofen were investigated as selectors for ketoprofen
enantiomers. The different relative intensities and characteristic band shifts of the two
enantiomers from Raman spectra suggest different interactions when complexed with β-
CD/HPβ-CD. Raman experiments revealed a noticeable diminishing of the C=C vibration
and ring deformation, which indicate the embedding of ketoprofen inside the β-CD cavity.
Both enantiomers showed a stoichiometry ratio of a 1:1 inclusion complex with β-CD and
HPβ-CD. The binding constant of R-ketoprofen (2750 M-1) and (1038 M-1) is higher than
S-ketoprofen (1299 M-1) and (799 M-1) with β-CD and HPβ-CD, respectively. These
values indicate that β-CD forms inclusion complexes more preferentially with Rketoprofen
than S-ketoprofen. This investigation was followed by qualitative surface
enhanced Raman spectroscopy (SERS) studies of β-CD/HPβ-CD inclusion complexes
with ketoprofen enantiomers using AgNPs and AuNPs as SERS substrate. In the second
part, the potential of L-cysteine capped with AgNPs (L-Cys-AgNPs) or AuNPs (L-Cys AuNPs) as chiral selectors for recognition of ketoprofen enantiomers have been studied.
Colorimetric sensors represent easy, inexpensive, simple and very effective visual chiral
recognition methods for the recognition of ketoprofen enantiomers. Rapid aggregation of
NPs occurred in the addition of R-ketoprofen, resulting in visible colour changes. The
chiral assay described in this work is easily distinguished with the naked eyes or using a
UV-Vis spectrometer. Both L-Cys-AgNPs and L-Cys-AuNPs sensors revealed a good
linear response to ketoprofen enantiomers in the concentration range of 8.33–33.33 μM.
The methods excel by their simplicity, low cost and good availability of materials. Both
qualitative and quantitative analysis were performed to test the capability of these
colorimetric sensors
Cellular and molecular signatures of cancer stem-like cells in hepatocellular carcinoma / Ain Zubaidah Ayob
No full textHepatocellular carcinoma (HCC) remains a highly lethal cancer with increasing global
incidence and mortality. Cancer stem cells (CSCs), or cancer stem-like cells (CSLCs)
have been considered as key drivers of cancer progression, and the enrichment of this
subpopulation is associated with aggressive and resistance cancer nature that causes
metastasis and tumour relapse. Better therapeutic strategy specifically targeting CSCs is
required for a more effective cancer treatment; however, the cellular and molecular
features as well as the regulatory mechanisms underlying CSCs remain unclear. This
study aims to investigate the molecular regulatory networks underlying the CSLCs in
HCC through their cellular and molecular signatures. Using in vitro approach as the
strategy to enrich CSLCs, three culture models were established using HepG2 cells
including 1) tumoursphere (3D-HepG2), 2) TGF-β1-induced epithelial-mesenchymal
transition (TβT-HepG2) and 3) cisplatin-induced resistant (CisR-HepG2) model. Using
serum-free media supplemented with 20 ng/ml of bFGF and EGF, 3D-HepG2 which was
established under low-adherent condition exhibited high sphere formation, proliferation,
and self-renewal capacity, with culture for 15 days result in high tumoursphere yield.
TβT-HepG2, established by treatment with 5 ng/ml TGF-β1 for 72 hours at 5000
cells/cm2 seeding density, displayed mesenchymal-like morphology with Vimentin, Snail,
Twist and Zeb1 upregulation corresponding with epithelial-mesenchymal (E-M) hybrid
characteristics. CisR-HepG2 was generated through three cycles of 72-hour cisplatin
treatment at IC50 concentration (6.62 ± 1.103 μM), which acquired resistance evident by
a 3.4-fold increase in IC50 value (22.55 ± 0.33 μM) and upregulation of drug transporters
and anti-apoptotic genes. The enrichment of CSC-like population in these models was
iv
evidenced by the increased fractions of ALDH+ population compared to parental cells,
whereas enhanced CD133 expression was only observed in the 3D-HepG2 model.
Comparatively, these models exhibited common features associated with increased
stemness quiescence, invasion/migration and resistance based on gene expression
analysis, whereas the proliferation and EMT features were differential between them.
Subsequently, integrated miRNA and mRNA analysis was performed to elucidate the key
regulatory networks underlying different CSC-like models. Microarray profiling revealed
22 miRNAs and diverse set of mRNAs were differentially expressed (DE) in the HepG2
derived CSC-like models compared to parental, with exclusive and overlapping
signatures observed between the three models. Seven miRNAs (miR-122-5p, miR-181a-
5p, miR-125a-5p, miR-29a-3p, miR-23a-3p, miR-92a-3p and miR-483-3p) identified to
be highly differentially expressed (>10 fold-change, p<0.05) with miR-19b-3p, miR-23a-
3p and miR-483-3p being commonly expressed by all the three models, suggest that these
CSLC-associated miRNAs might be critical in CSC regulatory networks. Functional
analysis revealed distinct regulatory networks including ‘TNF-signalling pathway’,
‘cAMP signalling’, ‘Rap1 signalling pathway’, ‘Proteoglycans in cancer’, ‘Systemic
lupus erythematosus’ and ‘FoxO signalling pathway’, with ‘Focal adhesion’, ‘p53
signalling’, and ‘Cell cycle’ were identified as common pathways in these CSC-like
models through the regulatory roles of these DE miRNAs. Collectively, this study
revealed distinct yet overlapping miRNA-mRNA signatures and regulatory networks
underlying CSC drives the CSC heterogeneity. The identified molecular regulators and
pathways of CSLCs from this study provide the avenues for future investigations and may
facilitate the development of therapeutic approach for CSC-targeted therapy in HCC
treatment
Generation of q-switched and soliton mode locked pulses with 8-hydroxyquinolino cadmium chloride hydrate and chromium aluminum carbide saturable absorber / Mustafa Mohammed Najm
No full textThis thesis describes the fabrication of new saturable absorber (SA) devices based on 8-Hydroxyquinolino cadmium chloride hydrate (8-HQCdCl2H2O) and chromium aluminum carbide (Cr2AlC) materials and test them in a ring-cavity Erbium-doped fiber laser (EDFL) for Q-switching and mode-locking applications. This study aims to develop an efficient and low-cost Q-switched and mode-locked fiber lasers operating in the nanosecond and picosecond regime, respectively using the newly developed SAs. The SAs are fabricated first using mechanical exfoliation and thin film methods, their physical, chemical, and optical characteristics are then investigated. The modulation depth of the exfoliated 8-HQCdCl2H2O on scotch tape, 8-HQCdCl2H2O thin film and Cr2AlC thin film are obtained at 11 %, 18 % and 3.2 %, respectively, indicating their suitability for Q-switching and mode-locking applications. Subsequently, the ring cavity is constructed using an Erbium-doped fiber as the gain medium, and the prepared SA is integrated and optimized into the laser cavity for Q-switched nanosecond and soliton pulse generations. Much time is then spent trying to optimize the cavity and utilize the 8-HQCdCl2H2O and Cr2AlC SAs successfully. The nanosecond pulse generation was successfully realized using the 8-HQCdCl2H2O or Cr2AlC film as SA. The Q-switched laser produced 726 ns pulses with a repetition rate of 150 kHz at pump power of 167 mW with 8-HQCdCl2H2O thin film. By optimizing EDFL cavity, mode-locked pulse train operating in 1.5 μm region with a pulse width within picosecond to femtosecond regime was successfully realized using the newly developed 8-HQCdCl2H2O and Cr2AlC SAs. These SAs successfully used to demonstrate different mode locked pulses in different EDFL cavities. For instance, femtosecond soliton pulses were obtained in the 33 m EDFL cavity. The laser produced a soliton pulse with the full width at half-maximum (FWHM) of 950 fs at a repetition rate of 5.6 MHz. These fiber lasers have many potential applications in various fields including biomedical imaging, material processing, and optical communication
Enhancing the contractual procedures and provisions for suspension of works in government projects / Anisha Shazwani Ahmad Anuar
No full textSuspension of works is widely discussed in the previous study as a remedy for late payment by the contractor. However, some situations may occur during the construction period where the suspension of works has to be taken such as the issuance of Movement Control Order (MCO) due to the Covid-19 pandemic. The procedure of implementing the suspension of works is given less attention due to the absence of detailed guidelines availability. The lack of understanding of what happens when a project is suspended also causes this matter to be ignored. Suspension of works is the privilege of the government to direct work on-site either in whole or in part to be stopped or delayed based on Clause 50 of PWD 203A form. Therefore, careful consideration should be given in deciding on the suspension of contractor works at the construction site. This research aimed to formulate enhancement to the contractual procedures and provisions for suspension of works in government projects. The objectives of the research are to determine the issues on suspension of works in construction projects, to analyze the current contract provision for suspension of works in the local standard form of contracts, and to assess the necessary improvement to the contractual procedures and provisions for suspension of works in government projects. The data for this research was collected and analyzed using a socio-legal research approach that included the standard form of contracts, current procedures, and legal cases concerning the suspension of work. Following that, a preliminary contractual provisions enhancement proposal was developed. The expert’s validation process was carried out through a focus group discussion to ensure that the research's findings were reliable. This research has identified the list of events and a fair time restriction mechanism for the suspension of work as the two essential enhancements that should be included in the contractual provisions for the suspension of work. The outcome of this research could also aid in the development of practical solutions for more effective work suspension in government projects
Mechanisms of glycerol electroreduction on activated carbon-based electrodes / Siti Aqilah Nadhirah Md. Rahim
No full textGlycerol generated from biodiesel manufacture is a beneficial waste that can be
potentially used to synthesize valuable products via the low-cost and simple setup
method, namely electrolysis. This waste can produce oxygenated and reduced compounds
through electrooxidation and reduction reactions, respectively. This work aims to study
the reaction mechanisms of glycerol electroreduction in the cathode region using
inexpensive activated carbon-based electrodes. The experiments were divided into three
sections. The first part is to synthesize the activated carbon composite (ACC) electrodes
with various activated carbon compositions. The influence of different activated carbon
percentages (60%, 70%, 80%, and 90%) of the total weight in the ACC electrodes on the
physicochemical and electrochemical properties was explored by field emission scanning
electron microscopy and energy-dispersive X-ray spectroscopy (FESEM-EDX), cyclic
voltammetry (CV), and chronoamperometry (CA) analyses. Results indicated that high
activated carbon content portrayed a dominant role in controlling an electroactive surface
area (EASA), and the electrons transfer process which eventually improved the
electrocatalytic activity. 80ACC outperformed other ACC electrodes by generating
Amberlyst-15 anionic radicals (A-15•-
) with the highest EASA (36.7 cm2
) and current
density (-0.2018 A/cm2
) at low potential. A-15•-
served as the electron-donor for the
homogeneous redox reaction with glycerol in delivering highly reactive glycerol radical
for further intermediates development and generated 1,2-propanediol. Meanwhile, the
low activated carbon percentage preferred diethylene glycol formation. Acetol and
ethylene glycol were subsequently suggested as the intermediates for 1,2-propanediol and
diethylene glycol formation, which were produced from the dissociation of glycerol either through the C-C bond or C-O bond cleavage, respectively. Hence, in the second part, the
proposed intermediates were employed as the glycerol substitutes to elucidate the overall
reaction mechanisms of glycerol electroreduction on the 80ACC electrode. Data proved
80ACC in Amberlyst-15 redox mediator solution demonstrated a superior activity for
acetol electro-hydrogenation into 1,2-propanediol. At 80 °C, 1,2-propanediol selectivity
(with 59.8 C mol% yield) reached 77.3% at the 7
th hour using 3.0 M of acetol and 0.28
A/cm2
current density. Whereas diethylene glycol was acquired through intermolecular
dehydration of ethylene glycol in the Amberlyst-15 solution without electricity. Besides,
H
+
ions from Amberlyst-15 are advantageous in facilitating glycerol conversion to a
selective acetol. Lastly, the preliminary experiments for glycerol electroreduction to study
the effects of reaction temperature (27-106.5 °C), initial glycerol concentration (0.3-4.35
M), and current density (0.07-0.28 A/cm2
) on the reaction were carried out. Findings
revealed the generation of acetol, and ethylene glycol intermediates was profoundly
controlled by the temperature where a mild value is needed to maintain a selective acetol 1,2-propanediol route. Additionally, a moderate glycerol initial concentration reduced the
hydrogen formation and indirectly improved 1,2-propanediol yield. A medium current
density raised the conversion rate and minimized the intermediates growth. At 80.0 °C
and 0.21 A/cm2
, glycerol (3.0 M) electroreduction to 1,2-propanediol reached the
maximum yield of 42.3 C mol%. The experimental value obtained was close to the
predicted yield (41.8 C mol%) from the polynomial model developed using response
surface methodology (RSM) and analysis of variance (ANOVA)