Universiti Kebangsaan Malaysia
  • Bangi, Selangor, Malaysia
Recent publications
To identify potential limitations that may impact the quality and efficiency of end-of-life vehicle (ELV) recycling and to provide solutions for effective management, this study investigates the current ELV recycling practice and the quality assessment systems around it in Malaysia by employing a mixed-methods approach. The approach encompasses qualitative and quantitative research alongside reviewing pertinent literature. The findings reveal that ELV recycling and its accompanying quality assessment systems in Malaysia are restricted and confront many critical challenges. The challenges include the lack of appropriate processes for recycling to maximize the material recovery, and the quality and reliability of the components put into circular economy practice. As a practical solution, a stakeholder-centric framework is proposed that allows better management of ELV waste from transportation and other related sectors. This framework enhances the efficiency and quality of ELV recycling practices in Malaysia and helps assess the quality of components recovered from ELVs.
Abundance of fine particulate-bound 16 priority polycyclic aromatic hydrocarbons (PAHs) was investigated to ascertain its sources and potential carcinogenic health risks in Varanasi, India. The city represents a typical urban settlement of South Asia having particulate exposure manyfold higher than standard with reports of pollution induced mortalities and morbidities. Fine particulates (PM2.5) were monitored from October 2019 to May 2020, with 32% of days accounting ≥100 μgm-3 of PM2.5 concentration, frequently from November to January (99% of days). The concentration of 16 priority PAHs varied from 24.1 to 44.6 ngm-3 (mean: 33.1 ± 3.2 ngm-3) without much seasonal deviations. Both low (LMW, 56%) and high molecular weight (HMW, 44%) PAHs were abundant, with Fluoranthene (3.9 ± 0.4ngm-3) and Fluorene (3.5 ± 0.3ngm-3) emerged as most dominating PAHs. Concentration of Benzo(a)pyrene (B(a)P, 0.5 ± 0.1ngm-3) was lower than the national standard as it contributed 13% of total PAHs mass. Diagnostic ratios of PAH isomers indicate predominance of pyrogenic sources including emissions from biomass burning, and both from diesel and petrol-driven vehicles. Source apportionment using receptor model revealed similar observation of major PAHs contribution from biomass burning and fuel combustion (54% of source contribution) followed by coal combustion for residential heating and cooking purposes (44%). Potential toxicity of B[a]P equivalence ranged from 0.003 to 1.365 with cumulative toxicity of 2.13ngm-3. Among the PAH species, dibenzo[h]anthracene contributed maximum toxicity followed by B[a]P, together accounting 86% of PAH induced carcinogenicity. Incremental risk of developing cancer through lifetime exposure (ILCR) of PAHs was higher in children (3.3 × 10-4) with 56% contribution from LMW PAHs, primarily through ingestion and dermal contact. Adults in contrast, were more exposed to inhale airborne PAHs with cumulative ILCR of 2.2 × 10-4. However, ILCR to PM2.5 exposure is probably underestimated considering unaccounted metal abundance thus, require source-specific control measures.
The Sunda Shelf plays a key role in the sedimentation of the southern South China Sea (SCS). However, the impact of past climate changes on sediment transfer to the Sunda Shelf and the southern SCS is still unresolved. Here we present new data on grain size, clay mineralogy, and Sr‐Nd isotopes of three marine cores, river sediments, and surface sediments of the Sunda Shelf. The results indicate that clay fractions of the central Sunda Shelf and the Gulf of Thailand derived mainly from the Mekong River and the rivers of northern Thailand since the last deglaciation. Significant changes in sediment sources are observed at 7.5 cal ka BP. From 13.3 to 7.5 cal ka BP, sediments in the Gulf of Thailand mainly originated from the rivers of northern Thailand, with contributions from the Mekong River increasing after 7.5 cal ka BP. An opposite shift is observed in the central Sunda Shelf. Such variations in the spatial distribution result from a combination of sea level and East Asian monsoon effects. After 7.5 cal ka BP, less Mekong River sediments were transported southeastwards into the southern SCS, and more sediments were gradually trapped within the delta and transported in a southwesterly direction into the Gulf of Thailand due to intense East Asian winter monsoon which forced a strong southwestward coastal current. Our results demonstrate the important impact of East Asian winter monsoon strengthening and sea level rise in the mid‐Holocene, which can change sediment sources and transport processes on the Sunda Shelf.
Autophagy is a highly conserved, lysosome-dependent biological mechanism involved in the degradation and recycling of cellular components. There is growing evidence that autophagy is related to male reproductive biology, particularly spermatogenic and endocrinologic processes closely associated with male sexual and reproductive health. In recent decades, problems such as decreasing sperm count, erectile dysfunction, and infertility have worsened. In addition, reproductive health is closely related to overall health and comorbidity in aging men. In this review, we will outline the role of autophagy as a new player in aging male reproductive dysfunction and prostate cancer. We first provide an overview of the mechanisms of autophagy and its role in regulating male reproductive cells. We then focus on the link between autophagy and aging-related diseases. This is followed by a discussion of therapeutic strategies targeting autophagy before we end with limitations of current studies and suggestions for future developments in the field.
Various foot complications, such as those due to diabetic mellitus(DM)-Diabetic Sensorimotor Polyneuropathy (DSPN), and Diabetic Foot Ulcer (DFU), could potentially be easily avoided by continuously monitoring plantar (foot sole) temperature at home. Systems, which can measure plantar temperature in real-time, still need investigation. This work has reported the synthesis, design, characterization, and implementation of a Laser-Induced Graphene (LIG) based smart insole capable of measuring plantar temperature. The solution provides an application for acquiring and storing the plantar temperature maps. Our proposed solution is lightweight, cheaper, and comparable in sensitivity, Limit of Detection, Range of Detection, Response Time, and Recovery time than other available solutions. The reported work is the first research where the LIG with excellent properties has been used in insoles. It can be used to generate temperature maps that effectively detect those at high risk of DFU and identify patients with severe DSPN.
This study aimed to examine the influence of performance expectancy (PE), effort expectancy (EE), social influence (SI), facilitating condition (FC), hedonic motivation (HM), perceived trust (PT) and lifestyle compatibility (LC) on the intention to adopt M-payment (IMP) as well as the mediating effect of IMP on the adoption of M-payment (AMP). This study adopted a cross-sectional design and collected quantitative data through an online survey from 309 respondents in China. The results revealed the significant positive influence of PE, EE, FC, HM, PT and LC on the IMP. The IMP was found to positively and significantly mediate the relationships of all predictors (except SI) and the actual usage of M-payment. Artificial neural network results validated the high prediction accuracy of the data fitness and highlighted the importance of PE, EE and LC on the IMP among Chinese users.
This paper describes and analyzes a workshop-based procedure to identify critical consumption and production (CP) linkages for sustainability, applied in the Klang Valley, an urban conglomeration centered in Kuala Lumpur and Putrajaya, Malaysia, targeting the year 2050. We propose a procedure combining a participatory backcasting approach, a structuralizing template, and scenario design cycles to identify critical CP linkages for sustainability. This procedure was tested in the Klang Valley, Malaysia, where resource and energy consumption is rapidly growing but scarcely studied. The workshops involved local experts from academia, industry, and government, as well as the research team, and established region-specific CP patterns, focusing on three domains, i.e., mobility, household chores, and living space. The results present key patterns for sustainable consumption and production in the Klang Valley and scenarios illustrating its implementation. Political will and strong regulatory enforcement with a particular focus on resource circulation at the end of life are identified as the dominant drivers to promote implementation.
Malaysia has maintained zero cases of indigenous human malaria since 2018. However, zoonotic malaria is still prevalent in underdeveloped areas and hard-to-reach populations. This study aimed to determine the prevalence of malaria among remote indigenous communities in Peninsular Malaysia. A cross-sectional survey was conducted in six settlements in Kelantan state, from June to October 2019. Blood samples were tested for malaria using microscopy and nested polymerase chain reaction (nPCR) targeting the Plasmodium cytochrome c oxidase subunit III ( cox3 ) gene. Of the 1,954 individuals who appeared healthy, no malaria parasites were found using microscopy. However, nPCR revealed seven cases of Plasmodium knowlesi mono-infection (0.4%), and six out of seven infections were in the group of 19 to 40 years old ( P = 0.026). No human malaria species were detected by nPCR. Analysis of the DNA sequences also showed high similarity that reflects common ancestry to other P. knowlesi isolates. These findings indicate low submicroscopic P. knowlesi infections among indigenous communities in Malaysia, requiring PCR-based surveillance to support malaria control activities in the country.
Virtual Reality (VR) is more common in education. Throughout the pedagogical process, because of the difficulty, and the need for logical reasoning and concepts, students experiment with problems with comprehension. Additional learning organizations began to incorporate influential innovation—established resources around the globe that can fulfill the demands of students’ varied populations. The new technology virtual reality has progressed since actually the focus related to entertainment toward career advancement over the past few years. It shows an essential role in education, offering an exciting, attractive, and likable technique for obtaining results. What follows is a description of significant changes in curriculum, prospects, and issues related to VR. This paper explains possibilities in VR and bringing collected greatest exciting, most recently VR technology in learning in many instruction fields, like education, industrial, and medical-associated education.
Over the years, there has been a growing interest among researchers to produce composite materials based on recycled thermoplastic matrices, which are available as waste materials in massive fraction. Evaluation of mechanical properties of these recycled or waste materials is one of the important scopes to be studied in the field of composite materials. The current book chapter reviewed the developments of recycled polyolefin matrix composite material, emphasizing their detailed mechanical performance such as tensile strength and elasticity modulus, flexural properties, impact strength, and so on. The focus was laid on the effect of blend composition, the effect of natural reinforcements such as rice husk fibers, wood flour fibers, the effect of artificial reinforcements such as glass fibers, and the effect of nano-sized filler such as nanoclay and carbon nanotubes in the recent development from 2015 to date.
This study addresses the inefficiencies in the current palm oil milling process, where the coexistence of mesocarp fiber and nut during pressing results in oil loss and nut breakage. To tackle this issue, the research aims to develop a machine that can separate mesocarp fibers from nuts before pressing, enhancing oil extraction and quality. The study involves designing the machine layout, creating schematic drawings, wireframe models, and assessing stress and deformation performance. Solidworks simulation was used to determine stress and deformation points within material properties, dimensions, and applied forces. The maximum stress on the rotating disc was 1.44 MPa, with a total deformation of 9.75 x 10⁻⁴ mm. Comparing this to the static component strength against cracking (0.093 MPa) revealed that the disc's material and design can safely with stand loads, preventing deformation during the mesocarp and nut separation process. This innovation promises to increase oil yields and improve oil quality in palm oil milling. Practical applications The separation of mesocarp fiber and nuts using centrifugal force is a feasible method. By removing nuts from the mesh (fiber) prior digestion and oil extraction process, the issue of nut breakage will be completely omitted, and thus the pressure can be further increased to maximize oil yield at the palm oil mill industries. This suggested approach has been demonstrated to produce a large amount of oil with minimal broken kernels. The crude palm oil obtained from this separation process also satisfies industrial standards.
In this article, a unique metamaterial (MTM) structure is presented that exhibits four resonances of transmission coefficient (S21) that fall into S, X, and Ku bands. The MTM design is initiated on a Rogers (RT5880) substrate with an electrical dimension of 0.088 λ × 0.088 λ (λ is calculated at 3.424 GHz). The resonating patch contains four quartiles connected by a central metallic strip. The placement of each quartile is such that the whole resonator is mirror symmetric about the vertical axis. Two H-shaped modifiers connect two quartiles of each vertical half of the resonator. These H-shaped modifiers form the resonance cavity in its vicinity, and thus help significantly to orient the overall resonances of the proposed MTM at 3.424 GHz, 10 GHz, 14.816 GHz, and 16.848 GHz. The resonance phenomena are examined through equivalent circuit modeling and verified in Advanced Design Software (ADS). Metamaterial properties of the proposed MTM are extracted and it exhibits negative permittivity, permeability, and refractive index. The prototype of the MTM is fabricated and measurement is taken. The measured S21 shows a close similarity with the simulated result. Moreover, effective medium ratio (EMR) is calculated for the proposed MTM and a high EMR of 10.95 is obtained that expresses its compactness. This compact MTM with negative permittivity, permittivity, and refractive index can be important component for improving the performance of the miniaturized devices for multi-band wireless communication systems.
The challenges on Si solar cells are the usage of hazardous phosphorus oxychloride (POCl3) for emitter formation and silane, and ammonia for the anti-reflective layer. This study focused on fabricating Si solar cells with less toxic material and an environmental-friendly process. The emitter junction was fabricated using a doctor blade (DB) with a less toxic phosphoric acid (H3PO4) fabrication method. The emitter formation used an H3PO4 solution with various concentrations and diffusion temperatures. The temperatures varied from 850 °C to 925 °C. The obtained measured sheet resistances were in the range of 40 Ω/sq – 60 Ω/sq, which were suitable as an emitter junction and comparable to the existing methods. The prediction of junction depth was determined using a mathematical calculation based on the sheet resistance obtained from experiments. Thus, for the device fabrication, 10% of the H3PO4 solution was deposited using the DB method with a 30 min diffusion time. The H3PO4 thin film deposited by the DB method on the Si surface showed that different solution concentrations and diffusion temperatures affected the surface roughness and sheet resistance at fixed diffusion time. SiO2 was used as an alternative for the passivation layer to replace the toxic SiNx on the front surface. The thickness obtained was 140 nm. Therefore, the use of less toxic materials and low-temperature processing in the emitter and passivation may produce comparable values to industries.
Background The downfall of formocresol as a pulpotomy medicament highlights the importance of cytotoxic evaluation and the establishment of a safe concentration of dental material prior to its usage in the oral cavity. Uncaria gambir is an herbal plant that possesses antimicrobial, anti-inflammatory and antioxidant properties, suggesting its potential as an alternative medicament for pulpotomy. However, there are not many studies published on its cytotoxicity, with some using non-standardised techniques and reported variable outcomes. Here, we investigated the concentration and time-dependent toxicity of Uncaria gambir extract towards the M3CT3-E1 cell line and compared it with the gold standard pulpotomy medicament: mineral trioxide aggregate (MTA). Methods Uncaria gambir extracts at concentrations ranging from 1000 to 7.8 µg/ml and MTA eluates at 4- and 48 h setting times were prepared. 10% dimethyl sulfoxide (DMSO) and culture media were used as positive and negative controls respectively. Cell viability on days 1, 2, 3 and 7 was analysed using Alamar Blue and Live and Dead Cell assay. Any morphological cellular changes were evaluated using transmission electron microscopes (TEM). Data were analysed using a two-way mixed Analysis of Variance (ANOVA). Results The interaction between the concentration and exposure time on the fluorescence intensity of Uncaria gambir extract and MTA 48 h was found to be statistically significant (p < 0.001). No cytotoxic effects on the cells were exerted by both MTA 48 h and Uncaria gambir extract at a concentration below 500 µg/mL. TEM analysis and Live and Dead Cell assay for both materials were comparable to the negative control. No significant differences in fluorescent intensity were observed between Uncaria gambir extract at 500 µg/mL and MTA 48 h (p > 0.05). Conclusion Uncaria gambir extracts at a maximum concentration of 500 μg/mL are non-cytotoxic over time and are comparable to the MTA.
Background A multidimensional voice quality assessment is recommended for all patients with dysphonia, which requires a patient visit to the otolaryngology clinic. The aim of this study was to determine the accuracy of an online artificial intelligence classifier, the Online Sequential Extreme Learning Machine (OSELM), in detecting voice pathology. In this study, a Malaysian Voice Pathology Database (MVPD), which is the first Malaysian voice database, was created and tested. Methods The study included 382 participants (252 normal voices and 130 dysphonic voices) in the proposed database MVPD. Complete data were obtained for both groups, including voice samples, laryngostroboscopy videos, and acoustic analysis. The diagnoses of patients with dysphonia were obtained. Each voice sample was anonymized using a code that was specific to each individual and stored in the MVPD. These voice samples were used to train and test the proposed OSELM algorithm. The performance of OSELM was evaluated and compared with other classifiers in terms of the accuracy, sensitivity, and specificity of detecting and differentiating dysphonic voices. Results The accuracy, sensitivity, and specificity of OSELM in detecting normal and dysphonic voices were 90%, 98%, and 73%, respectively. The classifier differentiated between structural and non-structural vocal fold pathology with accuracy, sensitivity, and specificity of 84%, 89%, and 88%, respectively, while it differentiated between malignant and benign lesions with an accuracy, sensitivity, and specificity of 92%, 100%, and 58%, respectively. Compared to other classifiers, OSELM showed superior accuracy and sensitivity in detecting dysphonic voices, differentiating structural versus non-structural vocal fold pathology, and between malignant and benign voice pathology. Conclusion The OSELM algorithm exhibited the highest accuracy and sensitivity compared to other classifiers in detecting voice pathology, classifying between malignant and benign lesions, and differentiating between structural and non-structural vocal pathology. Hence, it is a promising artificial intelligence that supports an online application to be used as a screening tool to encourage people to seek medical consultation early for a definitive diagnosis of voice pathology.
Significance: Bio-nanofluids have achieved rapid attention due to their potential and vital role in various fields like biotechnology and energy, as well as in medicine such as in drug delivery, imaging, providing scaffolds for tissue engineering, and providing suitable environments for cell growth, as well as being used as coolants in various energy systems, wastewater treatment, and delivery of nutrients to plants. Objective: The present study proposes a novel mathematical model for the ternary hybrid cross bio-nanofluid model to analyse the behaviour of blood that passes through a stenosed artery under the influence of an inclined magnetic field. The model considers the effect of expanding/contracting cylinder, infinite shear rate viscosity, and bio-nanofluids. Methodology: The considered model of the problem is bounded in the form of governing equations such as PDEs. These PDEs are transformed into ODEs with the help of similarity transformations and then solved numerically with the help of the bvp4c method. Findings: The results show that the flow rate and velocity decrease as the inclination angle of the magnetic field increases. Additionally, research has found that the presence of nanoparticles in the bio-nanofluid has a significant impact on the velocity and flow rate. Therefore, the flow rate decreases, in general, as the stenosis becomes more severe. Advantages of the study: The results obtained from this study may provide insights into the behaviour of blood flow in stenosed arteries and may be useful in the design of medical devices and therapies for the treatment of cardiovascular diseases. AM (2023), The significance of ternary hybrid cross bio-nanofluid model in expanding/ contracting cylinder with inclined magnetic field.
Most countries have suffered from prolonged budget deficits over the past two decades. This situation has made researchers and policymakers aware of the challenges to debt sustainability. This study investigates the threshold effect of institutional quality on debt sustainability in a panel of 82 countries, focussing on various threshold effects at different income levels. All the countries selected for this study fell under the categories of high income (HI), upper middle income (UMI), and lower-middle and low income (LMLI) based on the World Bank classifications. The dynamic threshold panel regression results indicate the presence of a threshold effect of institutional quality on the fiscal reaction function (including debt sustainability and cyclical fiscal policy) in all the countries with different income levels. In HI countries, fiscal adjustment weakens if institutional quality surpasses the threshold value of institutional quality. The fiscal adjustment in UMI countries is similar to that in HI countries but statistically insignificant. By contrast, governments in LMLI countries can promote sustainable debt if their institutional quality exceeds the threshold value. Thus, policymakers in LMLI countries need to prioritise their efforts to raise the level of institutional quality to promote debt sustainability.
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23,324 members
Naif H. Al-Hardan
  • Department of Applied Physics
Habibah Ahmad
Caryn Mei Hsien Chan
  • Faculty of Health Sciences
Saidah Saad
  • Faculty of Information Science and Technology
Universiti Kebangsaan Malaysia (UKM), 43600, Bangi, Selangor, Malaysia
Head of institution