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Nitrogen-doped graphene-based metal composites for the non-enzymatic detection of hydrogen peroxide / Mohammad Taghi Tajabadi Poor
Get PDFRecently, much attention has been devoted to detecting hydrogen peroxide (H2O2) because of its extensive range of applications in chemical synthesis, the textile industry, food production, fuel cell devices, and even in many oxidative biological reactions. Among the various methods of detection of H2O2, electrochemical sensors has many advantages, such as simplicity, high efficiency and sensitivity, as well as good selectivity., To improve the sensitivity of non-enzymatic sensors, noble metal nanoparticles with particular electrocatalytic activities can be utilized. The present research is aimed to design a hybrid approach for the development of novel nanostructures for non-enzymatic detection of H2O2. Herein, the electrochemical measurements were performed using a potentiostat/galvanostat. A X-ray powder diffractometer (XRD), transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) were utilized to investigate the phase structure and composition, as well as morphology and particle size of the electrodes. In addition, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) were also utilized to further investigate the structural and electronic properties and to identify the nitrogen-bonded groups in the as-synthesized nitrogen doped graphene (NG), respectively. For this purpose, NG was initially prepared using a microwave-assisted method that comprises of a three-step process of graphite oxidation, exfoliation, and chemical reduction using a reducing agent at low temperature. In the first
step, NG was electrophoretically deposited (EPD) on an indium tin oxide (ITO) electrode, following by silver nanodendrites (AgNDs) and platinum nanoflowers (PtNFs) as the subsequent layers via electrochemical deposition. The as-prepared AgNDs/NG-modified ITO electrode was used as a non-enzymatic H2O2 sensor and exhibited high stability, outstanding reproducibility and good electrocatalytic activity for the quick detection of H2O2 over a wide linear range from 100 μM to 80 mM. In the second case, PtNFs/Ngmodified ITO electrode with different NG loadings were utilized as non-enzymatic H2O2 sensors, where ITO modified with 0.05 mg ml−1 NG loading exhibited improved properties for H2O2 detection over a linear range from 1 μM to 1 mM
Fuzzy logic based control for membrane oxygenator in blood purification process / Hany Hazfiza Manap
Get PDFMembrane oxygenator in Extracorporeal Life Support (ECLS) is commonly used as a main component in Cardiopulmonary Bypass (CPB), Extracorporeal Membrane Oxygenator (ECMO) and Extracorporeal Carbon Dioxide Removal (ECCO2R). In this study, the focus is on Carbon Dioxide (CO2) gas exchange process in membrane oxygenator, which the CO2 is automatically controlled by adjusting sweep gas flow rate that entering the membrane oxygenator in achieving the desired pCO2 required by the particular patients. This automatic control action is controlled by the implementation of three controllers, Proportional-IntegralDerivative (PID) that is tuned by Ziegler-Nichols continuous cycling method, Fuzzy Logic Controller (FLC) and Fuzzy-PID controllers. This study is conducted in two stages: simulation and experimental work for two tasks, namely setpoint tracking and disturbance rejection. For evaluation of setpoint tracking, desired setpoint of arterial partial carbon dioxide (pCO2) is set at 40 mmHg at the beginning of the process, and been increased by 5% to 42 mmHg at the middle of the process, and been adjusted back to 40 mmHg at the end of the process. For disturbance rejection, an external disturbance is applied to the process plant (in membrane oxygenator) by a sudden shutoff of mass flow controller (MFC) to stop the sweep gas flow rate until 0 L/min at the middle of process. All the simulation works are done using level-2 SFunction in MATLAB/SIMULINK environment. An application of NI-USB 6009 DAQ in corporation with MATLAB/SIMULINK environment is used for both pCO2 sensors and mass flow controller as an actuator to control sweep gas flow rate in the experimental work. FuzzyPID recorded the best performance in both setpoint tracking and disturbance rejection tasks during simulation. The control performance become worst with loss of control action in experimental setting using similar PID and FLC parameters/rules, due to some assumptions and defined parameters in mathematical modelling that are differ than actual parameters used in experimental work. Re-tune process is conducted to calculate newly parameter for PID and rule for FLC and Fuzzy-PID. The proposed controllers then able to automatically control CO2 gas transfer in membrane oxygenator according to the desired setpoint. As a conclusion, all the controllers produce a good ability to automatically control CO2 removal from membrane oxygenator for both tasks, with Fuzzy-PID outshines the other controllers, PID and FLC. This can be seen from the lowest performance indices and the time taken to achieve the setpoint for Fuzzy-PID is lower by 21.15% compared to PID and 65.25% lower compared to FLC during setpoint tracking task. For disturbance task, Fuzzy-PID also recorded the fastest time to adapt with the disturbance, which 89.33% and 51.52% faster than PID and FLC, respectively. Hence, this in-vitro bench set-up has great potential to be further extended study
Antioxidating effect of Ampelocissus sp. (Isi Nyaru) on streptozotocin-induced diabetic Rats / Elly Zulaikha Zamri
Get PDFThe Ampelocissus sp. locally known as Isi Nyaru has been traditionally used by native Malaysian for medical purpose. The tuber was extracted with hexane, petroleum-ether, chloroform, methanol and water solvents. The seperation and detection of bioactive compounds were done using Thin Layer Chromatography (TLC) and Gas Chromatography Mass Spectrometry (GCMS) methods. The TLC results showed the presence of phenolic acids, flavonoids and terpenoids. While in GCMS has revealed the presence of hydrocarbon groups such as alkene, ester and ether, amino acid groups, dicarboxylic acid and cyclic aromatic compound. The total phenol content and total flavonoid content were highest in methanolic extract at 748.50 ± 0.01 mg (TAE)/g and 27.08 ± 0.04 mg (QE)/g respectively. The extracts were tested for antioxidant activities by DPPH radical scavenging activity, ferrous ion chelating activity (FCA) assays and ferric reducing antioxidant power (FRAP) assays. The methanol and water extracts rich in phenol and flavonoid based on Thin Layer Chromatography (TLC) result, exhibit the strongest antioxidant activities to DPPH, FCA and FRAP. According to IC50 reading of DPPH and FCA, methanol extract indicated 1.27 μg/mL and 1.72 μg/mL respectively while water extract indicated 1.22 μg/mL and 1.62 μg/mL respectively. The FRAP value for water extract is 11.73 mmol/g and 11.58 mmol/g for methanol extract. The Streptozotocin (STZ) diabetic-induced rats have been treated by 4000 mg/kg of methanol extract in acute oral toxicity test with no toxicity effects observed in rats. Methanol extract has been chosen for the anti-diabetic treatment of diabetic rats based on its free toxicity effects and has the largest yield production. The blood glucose concentration of methanolic-treated diabetic rats showed the significant reduction which 17.4% (800 mg/kg methanol extract) and 12.4% (800 mg/kg methanol extract), while 21% reduction in glibenclamide-treated diabetic rats. There are slightly increased of body weight in diabetic rats treated with 800 mg/kg and 400 mg/kg methanol extract and glibenclamide which are 1.7%, 2.6% and 3.3% respectively. The activity of antioxidant enzymes which are catalase (Cat) and glutathione peroxidase (GPx) in diabetic rats showed a positive result when treated with extracts and standard. The results concluded that the antioxidant activity of methanol extract was primarily due to the high amount of phenolic and flavonoid content
A multimodal analysis of Bangladeshi fairness product advertisements / Shushmita Hossain Khan
No full textThe notion of beauty is associated with fair skin tone in Bangladesh. Bangladeshis have varied skin tones although generally most of the people have a dark complexion. Fairness product advertisements tend to suggest that fair complexion is essential for marriage, successful career and promote that using their products can help women to achieve the perfect face, partner, and expected behavior from the society as well as acceptance from the opposite sex. This indicates that fair skin means superiority and beauty in Bangladeshi context. Although these advertisements have gone through some changes in last five years, within these, the advertisements still seem to influence women with similar messages using but different strategies. The study aims to highlight the use of multimodal resources in Fair & Lovely fairness-product advertisements and techniques applied by the advertisers to influence their customers. Kress and Van Leeuwen’s framework of multimodal analysis (1996) along with Machin (2016) and Ledin and Machin (2018) are utilized as analytical tools. To investigate this issue, this study undertakes the analyses of two data sources: 10 television advertisements (multimodal analysis) and triangulated with 35 responses through an online survey (thematic analysis). Findings suggest that the advertisers use various discursive techniques to influence women to reconstruct their ideology of “fairness” and “beauty” through visual and verbal aspects of the advertisements
Classification of dividend news based on the movement of the share market prices of public listed companies in Bursa Malaysia / Shubana Vijaya Kumar
No full textStock market is naturally complex and plays a major role in towards the nation’s growth. However, the performance of a company in stock market varies due to many influences but not limited to economics, political and financial related news. This study attempts to classify the share market dividend news announcement in Bursa Malaysia based on the pattern of share market price. Samples including five hundred (500) observations of dividend news from forty-seven (47) listed companies in Bursa Malaysia during the period of 2000 to 2018 are used in this study. There are three (3) main objectives in this study which consist of (1) to propose a dividend news classification, (2) to develop a dividend news classification system and (3) to evaluate the accuracy of the news classification approach. The first objective is achieved by proposing a news classification approach to classify the dividend news based on announcement date price, ex-date price, entitlement date price and payment date price. This research uses historic data to analyse and classify the dividend news. The dividend news classification approach is determined by comparing daily closing price difference from the dividend announcement date until dividend payment date and price difference between the four (4) dates - dividend announcement date, ex-date, entitlement date and dividend payment date. The dividend news is classified as a good news if the price difference is more or equal than zero and if it is lower, it is classified as a bad news. Second objective is achieved with the development of the dividend news classification system by imposing the mathematical approach which calculates the price difference between the announcement date, ex-date, entitlement date and payment date. The news classification system is developed by using Joget Workflow which is an open source platform. In addition, the accuracy of the proposed mathematical approach for dividend news classification system is evaluated using five (5) different Machine Learning Model which consist of Logistic Regression (LR), Linear Discriminant Analysis (LDA), K Neighbours Classifiers (KNN), Gaussian Naïve Bayes (NB) and Support Vector Machine (SVM). As per to achieve the third objective of this study, the mathematical approach is strongly supported by Logistic Regression (LR) model with the highest accuracy of 0.98. The outcome of this study helps to facilitate the investors in interpreting the dividend news easily and faster with simplified methods. Finally, it is important to the investors who would like to analyse and study the dividend news trend in the past years
Psychometric properties of Bergen social media addiction scale (BSMAS) in Malay version / Romi Tiong Kee Hui
No full textBackground The percentage of internet users in Malaysia has recorded continuous increment
annually, in which it increased from 76.9% in 2016 to 87.4% of users in 2018. The prevalent
use of all sorts of social media platform and the convenient access to the internet regardless
of time and place has massively enhance the potential of social media addiction. After many
years of research, the researchers have yet to reach the consensus in identifying criteria to
diagnose problematic attachment to social media. The aim of the study was to validate the
Malay version of Bergen Social Media Addiction Scale (BSMAS), by using a sample of 166
University of Technology Malaysia (UTM) students. Methods A cross sectional study was
conducted at UTM, Johor Bahru. After translation stage and face validity were done, the
result of the sample collection was subjected for internal consistency test, construct validity
by using CFA method and subsequently testing of the fit indices. Results The instrument
exhibited good internal consistency (Cronbach’s alpha = .8) and concurrent validity with
Internet Addiction Test (IAT) (Pearson’s correlation = .56, p<.001). IAT was used as the
gold standard to determine the cut-off point of BSMAS. Receiver Operating Characteristic
(ROC) analysis demonstrated that 10 point was the cut-off score to differentiate the students
with and without problematic social media use (composite score of 0 – 24). The analysis of
CFA [Comparative Fit Index (CFI) = 1.000; Tucker Lewis Index (TLI) = 1.000; root mean
square error of approximation (RMSEA) = <.001; Standardized root mean square residual
(SRMR) = .019] confirmed the unidimensionality of the BSMAS. The score of BSMAS is
correlated with IAT and the “addictiveness to the social media and academic performance”
in SMAAPOS; negatively correlate with BBQ and no correlation with other components in
SMAAPOS such as “use and exposure of social media in academic performance”, “age and
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gender use of social media with academic performance”. Conclusion The Malay version of
the BSMAS appeared to be a valid and reliable instrument for assessing problematic use of
social media use in Malaysian University students.
Keywords: BSMAS, social media, addiction, Malaysia, reliability, validit
A three dimensional age estimation using cone beam CT in Malaysian population / Muhammad Khan Asif
No full textForensic odontology plays a vital role in the age estimation and identification process
during criminal investigations. Forensic science in the past have mainly employed two-dimensional (2D) radiographic assessment of developmental and physiological age
related dental parameters for age estimation. However, 2D radiograph doesn’t represent
the three-dimensional (3D) anatomical structures. Rapidly evolving CBCT imaging
modality can be effectively employed in forensic sciences to overcome the limitations of
2D imaging. The current study aimed to develop a novel method of dental age estimation
using 3D surface area analyses of root apices of the developing permanent maxillary
canines and mandibular third molars among Malaysian population using CBCT data. Two
new and validated dental age estimation regression equations were developed. The first
regression equation was developed for Malaysian children aged 7 to 14 years by assessing
the relationship between chronological age and surface area of the developing maxillary
canine apex. Variations based on ethnicity (Malay/Chinese), gender and status of root
development (open/closed) were also investigated in terms of fit to the age estimation
model. The training sample of 191 permanent maxillary canines was selected from the
CBCT images belonging to 100 Malays and 91 Chinese. Moreover, an independent
validation sample of 96 permanent maxillary canines was also selected. Multiple linear
regression analysis was used to derive an age estimation model using chronological age
as a dependent variable and surface area of the maxillary canines apices, ethnicity, gender
and status of the root development (open/closed apices) as predictor variables. A strong
correlation (r = 0.978) was observed between chronological age and the predictor
variables. 95.6 % of the variation in age was explained by the surface area of canine apex,
gender and status of the root development (open/closed apices). However, ethnicity did
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not contribute to the fit of age estimation model. Mean absolute error (MAE) value of
0.30 was observed when tested on an independent validation sample. The second
regression equation was developed for Malaysian juveniles and young adults aged 13 to
24 years by assessing the relationship between chronological age and surface area of the
developing mandibular third molars apices. The training sample of 128 intact mandibular
third molars was selected from the CBCT images belonging to 66 Malays and 62 Chinese.
In addition, 55 mandibular third molars were selected as a validation sample. Multiple
linear regression analysis was used to derive an age estimation model using chronological
age as a dependent variable and surface area of the mandibular third molars apices,
ethnicity, gender and status of the root development (open/closed apices) as predictor
variables. A strong inverse correlation (r = 0.95) was observed between chronological age
and all the predictor variables. The results showed that 89.6% of the variation in age can
be explained by the predictor variables. MAE value of 0.822 was observed when the
derived regression equation was tested on the independent validation sample. In
conclusion, 3D surface area analysis of the developing root apices can be used as a
reliable method for age estimation in Malaysians.
Keywords: CBCT; Age estimation; Three-dimensional; Malaysian
Young-onset hypertension in Malaysia: A mixed-methods study / Khoo Yi Yi
No full textThe continuous cumulative presence of raised blood pressure (BP) when young is a strong
predictor of future cardiovascular risk. This study, which was conducted between June
2018 and December 2019, aimed to elucidate the epidemiology of young-onset
hypertension (YOH) in Malaysia during the period 2006–2015, and to explore the
underlying experiences and perspectives of young adults living with hypertension. Phase
I involved a systematic review to identify variables for the secondary data analysis. In
Phase II, data on respondents aged 18–39 diagnosed with YOH according to the 7th Joint
National Committee Report (United States) were extracted from three National Health
and Morbidity Surveys (2006, 2011, and 2015). Univariate analysis was used to examine
associations between YOH and baseline characteristics; Chi-square test for categorical
variables and analysis of variance for continuous variables. All potential confounding
factors were adjusted for using multiple logistic regression analyses. In Phase III, an
interpretive phenomenological approach was adopted to conduct in-depth interviews
among hypertensive young adults recruited from the Department of Primary Care
Medicine, University of Malaya Medical Centre. Interviews were conducted until
saturation point, transcribed verbatim, followed by content analysis and thematic coding.
In Phase I, twenty studies showed considerable variability in YOH epidemiology and
trends worldwide. Phase II analysis revealed that the prevalence of YOH in Malaysia
remained stable during 2006–2015: 17.7%, 95% CI [17.0, 18.3] in 2006, 17.0%, 95% CI
[16.0, 17.9] in 2011, and 18.4%, 95% CI [17.4, 19.4] in 2015. Awareness, treatment, and
control rates were suboptimal: 15% were aware of their diagnosis, of which less than 50%
were on treatment and less than 40% of those on treatment had their BP controlled.
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Significant positive associations were found with sociodemographic (male, increasing
age, primary education, lower income group, positive family history) and cardiovascular
risk factors. The Phase III analysis revealed that young Malaysian adults were concerned
about self-stigma associated with YOH and displayed a lack of insight regarding the
factors involved in developing YOH. Moreover, there was cognitive dissonance between
knowledge and practice. Barriers to treatment adherence were attributed to personal
(time), treatment (side effects), and disease (being asymptomatic) factors. Facilitators
included social support, high self-efficacy, perceived threat and severity of disease,
experiencing symptomatic relief, and role-modelling. Unmet needs included shared
decision-making with healthcare professionals, having long-term expectations of
treatment addressed, and the usage of social media and hypertension education materials
to intensify awareness of YOH among peers. The results of this study narrow the
knowledge gap on YOH epidemiology in Malaysia by providing crucial information on
the pervasiveness of hypertension among young adults. They also indicate that an
understanding of young adults’ lived illness experiences is critical to improving treatment
adherence and BP control. Additionally, they highlight the need to treat young adulthood
as a separate entity in research planning, programming, and policymaking. Thus, this
study provides a basis upon which health policymakers and relevant stakeholders can
build non-communicable disease policies and health promotion strategies specially
targeted at young adults who are in the prime of life.
Keywords: Cardiovascular disease, epidemiology, Malaysia, young-onset
hypertension, young adult
Association between stigma, psychological distress, and quality of life among people living with HIV in federal territory of Kuala Lumpur / Khairiah Ibrahim
No full textQuality of life is an important component in the evaluation of the well-being of
PLHIV. However, HIV stigma and psychological distress (depression, anxiety and stress)
continue to be a barrier to obtain a good quality of life among PLHIV globally. This study
assesses the level of QOL, stigma and psychological distress among PLHIV in Kuala
Lumpur by determining the association between QOL, stigma and psychological distress.
A cross-sectional study was conducted, involving 305 PLHIV attendees of the infectious
disease clinic in a teaching hospital, primary health clinic and three Community-Based
Organisations (CBOs). The sampled respondents completed face to face interviews using
a standardised structured questionnaire on quality of life scale (WHO-QOL HIV BREF),
Depression, Anxiety and Stress Scale (DASS) and HIV Stigma Scale. Total quality of life
of respondents in this study was in the low to moderate range (mean 93.7; SD 15.6) and
was significantly impaired by the social relationship domain (mean score 12.9; SD 3.2)
followed by the spirituality domain (mean score 12.4; SD 2.4). On the other hand,
psychological domain (mean score 13.8; SD 2.7) and ability to perform daily activities
(physical domain) was not affected by the illness (mean score 13.7; SD 3.08). The mean
total QOL was significantly higher among respondents from the teaching hospital and
primary health clinic compared to CBOs respondents, which could be due to the
availability of HAART treatment. The overall stigma experienced by PLHIV in this study
was moderate (mean score 100.4; SD 17.3). Stigma was highest in the disclosure domain,
where difficulty to disclose HIV serostatus may be influenced by the cultural and religious
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belief of PLHIV. It is interesting to note that PLHIV in this study least experienced
negative self-image stigma (shame and guilt). This may reflect them having a high
perceived stigma but low internalised stigma, which suggests they did not experience the
negative consequences of stigma. Stigma was associated with higher odds of depression
(Adjusted OR 1.05, 95% CI 1.02-1.07), anxiety (Adjusted OR 1.04, 95% CI 1.02-1.06)
and stress (Adjusted OR 1.03, 95% CI 1.00-1.06) and was negatively correlated with all
QOL domains. This study also found that psychological manifestation was prevalent
among PLHIV with 48.7% of respondents having depression, 58.4% anxiety and 30.5%
stress. Depression, anxiety and stress were negatively associated with all QOL domains
and associated with lower odds of good quality of life (Adjusted OR 0.92, 95% CI 0.89-
0.94) for depression, (Adjusted OR 0.94, 95% CI 0.92-0.96) for anxiety and (Adjusted
OR 0.92, 95% CI 0.90-0.95) for stress. In conclusion, these findings confirm that stigma
and psychological distress make a distinctive, significant contribution to overall QOL.
Therefore, focus on efforts to diagnose and treat depression, anxiety and stress while
enhancing spiritual and psychological support are strategies to improve QOL among
PLHIV. Finally, it is important to address disclosure stigma among PLHIV by having
active interaction between PLHIV with healthcare workers, family members, employers
and the society to empower and provide safe disclosure among PLHIV.
Keywords: PLHIV, QOL, depression, anxiety, stress, stigma, HAAR
Association of chronic pain with physical function and mortality among older adults in rural Malaysia / Chan Yee Mang
No full textOlder adults are postulated to double in 2017 and 2050 worldwide, including Malaysia.
Various challenges are related to ageing population, including poor physical functioning
and increase number of chronic diseases. Chronic pain is often associated with chronic
disease. Chronic pain affects almost one third of the world’s adult population and higher
prevalence reported among older adults. Evidence suggests that chronic pain has
undesirable consequences on physical, mental health and premature mortality. In low�and middle-income countries, there are limited studies examining the consequences of
chronic pain on physical function and premature mortality. The aim of this study is
therefore to determine the association between chronic pain and physical disability,
functional limitations and five-year mortality. The design of the study was a secondary
analysis of existing cohort data in Kuala Pilah, Negeri Sembilan, Malaysia. Baseline
assessments were conducted from November 2013 to February 2014. Twelve months
follow-up data were collected from December 2014 to February 2015. The study
population was older adults 60 years of age and above living in Kuala Pilah for a
minimum period of 12 months prior to data collection. Respondents were excluded if they
were not Malaysian citizens, living in nursing homes, admitted to hospital during the
interview, refused to participate or had severe cognitive impairment. Logistic regression
was used to examine cross-sectional associations between baseline chronic pain and
outcomes of interest. Generalized Estimating Equation was used to examine longitudinal
associations between baseline chronic pain and outcomes of interest. Cox Proportional
Hazard model was used to examine the association between chronic pain and five-year
mortality. The prevalence of chronic pain was 21.1% (95%CI 19.4, 22.8). Chronic pain
was associated with higher risk of ADL disability (RR 2.14; 95%CI 1.38, 3.46) and IADL
disability (RR 1.30; 95%CI 1.04, 1.62). However, chronic pain was not associated with
higher risk of slow walking speed (RR 1.01, 95%CI 0.79, 1.29) and low handgrip strength
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(RR 1.15; 95%CI 0.94, 1.40). The five-year mortality rate was higher in respondents with
chronic pain (26.24%) compared to those with no chronic pain (18.51%). But, no
significant association was observed (HR 1.09; 95%CI 0.84, 1.41). Early detection of
chronic pain and appropriate pain management are important for the management of high
chronic pain distribution among older adults in Malaysia. Effective interventions and
preventive strategies are crucial to reduce the risk of ADL and IADL disabilities among
older adults with chronic pain. Recommendation on adequate level of physical activity
could be one of the preventive strategies to reduce the risk of ADL disability, IADL
disability and five-year mortality. It is hoped that the findings of this study will be used
to improve chronic pain management in the existing guidelines for pain management in
local setting.
Keywords: Older adults, chronic pain, physical disability, functional limitations,
mortalit