13474 research outputs found
Sort by
Knowledge and attitude of employees towards noise pollution in latex glove manufacturing industry / Ngam Kai Sien
No full textThe aim of this study was to determine employees’ knowledge and attitude towards noise pollution in latex glove manufacturing industry. A cross-sectional study was conducted involving 100 employees from latex glove manufacturing plant located at Meru, Klang. Questionnaire survey were being distributed among the 100 respondents to retrieve the socio-demography, working profile, knowledge, and attitude towards noise pollution. It was found that only 32% of the total respondents have passed the knowledge test from the questionnaire survey mainly due to the education level of the respondents. Some of the weak areas in terms of knowledge are the prevention knowledge and cause of NIHL knowledge. Besides that, the results also shows that overall mean score of the respondents’ attitude is 64.18%, which is higher when compared to the mean score of knowledge (43.62%) due to proper enforcement and effective practical training by the employers. However, some of the weak areas for the overall respondents in terms of attitude towards noise pollution is their health seeking attitude and risk-taking attitude. Lastly, it was found that the nationality, education level and the department of the employees will affect how well is their knowledge and their attitude towards noise pollution. These data were proven significance difference by conducting one way ANOVA analysis using SPSS Software. It is very crucial to have theoretical educational programmes on general prospects of noise pollution and prevention of noise induced hearing loss to the employees to further improve their awareness towards noise pollution
Improvement of the vehicle warm-up performance through low thermal inertia exhaust heat recovery unit / Azmi Osman
No full textInternal combustion engines in general waste plenty of heat to the exhaust gas and coolant for every milligram of fuel burned. Considering that daily driving consists of frequent cold start, idling and part load driving within short driving distances, the potentials to recover heat from high enthalpy exhaust gas are limited to hard acceleration, hill climbing and highway driving. These constraints limit many heat recovery technologies that rely on conversion of thermal energy into electricity or kinetic energy. In recovering precious energy from the low enthalpy exhaust gas early and sustainably, a low thermal inertia exhaust heat recovery unit (EHRU) is proposed to be integrated to the simplified split cooling circuit used in the earlier studies to expedite the powertrain warm-up. This lightweight, compact and simple EHRU concept made of machined steel plate is targeted for naturally aspirated engines that are still being widely used in motorcycles, stationary engines and small car segments worldwide. Large temperature difference between the coolant and exhaust gas was possible using cooler coolant feed from the bottom of the cylinder block�s water jacket rear end. To prove its effectiveness in speeding up the recovered heat availability for reuse, a 1.3l passenger car equipped with strategically placed multiple thermocouples and flow meters was tested using idle and NEDC tests. The EHRU was later modeled using a simplified energy system (SES) to overcome the experimental limitations. From the experiments and classical analysis, the recovered thermal energy was available in just 23-25 seconds instead of 50 seconds after cold start. The improvements over the variant with no EHRU revealed during the idle and NEDC tests are in the range of 0.9-13.9% and 1.6-25.1% respectively. The study also provided a new direction in the design of EHRU and its integration into an engine
Association between anthropometric measurements and dental caries among children in Asia: A systematic review and meta-analysis / Rokiah Mamikutty
No full textOverweight and dental caries among children is increasing in Asia. The association
between anthropometric measurements and dental caries is inconclusive and not
representing the Asian context. Aim: To assess the association between anthropometric
measurements and caries among children in Asia by regions, sugar consumption per-capita, and SES of the countries. Methods: The review was registered with PROSPERO
and conducted following PRISMA guidelines. Twenty-six databases were employed for
searching the eligible studies from inception until Jun 2019. Two reviewers independently
screen, select studies, perform data extraction, and risk bias assessment, with
discrepancies resolved by discussion and reference to the third reviewers. Meta-analysis
was performed using a random-effect model. Heterogeneity was assessed using chi�square and quantify with Higgin I2
statistic. A sensitivity analysis and reporting bias was
assessed using funnel plots. Subgroup analysis was conducted by regions, sugar
consumption per-capita, and socio-economic of the countries. Harvest plot was employed
when meta-analysis is inappropriate. Quality of evidence was rated with
GRADE. Results: 4532 studies retrieved. Sixty-six studies were included after
deduplication, title, and abstract and full-text screening. Fifty-three studies were pooled
in meta-analysis and 13 studies analysed by Harvest plot. For primary dentition, BMI was
negatively associated with caries prevalence and caries severity. Overweight (OR: 0.64;
95%CI 0.53, 0,77) or obese children (OR: 0.58; 95%CI 0.44, 0.77) were less likely to
have caries compared to normal weight, and underweight children (SMD: 0.15; 95%CI
0.05, 0.25) have caries severity compared to normal weight. No significant association
iv
was observed between BMI, WC, WHtR, SFT and caries in permanent dentition. In mixed
dentition, obese children (OR: 0.60; 95%CI 0.52, 0.69) are less likely to have caries than
normal weight. In South Asia, West Asia, East Asia, high-income, upper- and lower�middle-income countries, overweight children are less likely to have caries in primary
dentition than normal-weight children. Highest inequalities are in South Asia, countries
with sugar consumption per-capita higher than the WHO recommendation and lower�middle-income countries. In West Asia, East Asia, high-income, and upper-middle�income countries, obese children are less likely to have caries in primary dentition than
normal-weight children. Highest inequalities are in West Asia and high-income countries.
Underweight children have more caries in primary dentition in South Asia, East Asia, and
West Asia, the highest inequalities in South Asia. In permanent dentition, underweight
children from South Asia are less likely to have caries. Also, in lower-middle-income
countries, underweight children less likely to have more caries in permanent dentition
than normal-weight children (positive association). In high-income countries,
underweight children have more severe caries than normal-weight children. Overweight
and obese children are less likely to have caries in permanent dentition than normal�weight children in West Asia, a negative association. These findings are rated as low to
very low by GRADE. Conclusion: In Asia, the negative association between BMI and
caries is revealed in the primary dentition. Regions, sugar consumption per-capita, and
SES of countries influenced the association between BMI and caries. Future studies for
other anthropometric measurements than BMI, studies from South East Asia and Central
Asia are required
Fear of Covid-19 among nurses in University Malaya Medical Centre: The prevalence and its association with anxiety, depression and the coping strategies / Farah Nabila Abd Majid
No full textIntroduction: The current COVID-19 pandemic has significantly caused an escalation
in mental health issues among nurses. Aim: This study aims to determine the level of fear
of COVID-19 and its association with socio-demographic factors, COVID-related
factors, coping styles, anxiety and depression. Methods: A cross-sectional study was
conducted via online survey. A total of 814 nurses from various disciplines in UMMC, a
tertiary teaching hospital in Malaysia participated in the study. Sociodemographic data,
COVID-related data and a set of validated questionnaires were used to measure fear of
COVID-19, anxiety, depression and coping strategies. Results: The prevalence of high�level fear of COVID-19, anxiety symptoms and depressive symptoms were
71.5%(n=582), 21.0%(n=171), and 17.9%(n=146), respectively. Providing care to non�COVID-19 patients significantly predicted higher level of fear of COVID-19 (adjusted
OR of 1.55, 95% CI 1.06-2.28, p<0.05). Nurses who perceived increased in their work
burden was significantly associated with fear of COVID-19 (adjusted OR 0.61, 95% CI
0.43-0.89, p<0.05), anxiety (adjusted OR 0.44, 95% CI 0.26-0.76, p<0.05) and depression
(adjusted OR 0.56, 95% CI 0.32-0.89, P<0.05). Fear of COVID-19 was positively
correlated with both anxiety and depression with r value of 0.49 and 0.39, respectively.
Avoidant coping strategy was significantly and positively correlated with all three
psychological complications which were fear of COVID-19, anxiety and depression, with
a coefficient of correlation, r, of 0.29, 0.46 and 0.27, respectively. Conclusion: There
was a high level of fear of COVID-19 among nurses. Nurses who did not provide direct
care and had increased work burden were more fearful of COVID-19. Using avoidant
oriented coping was associated with negative psychological outcome. Thus, strategies to
address psychosocial issues and enhance effective coping skills among nurses should be
implemented to prevent detrimental psychological outcome amongst nurses regardless of
whether they are providing direct or non-direct care to COVID-19 patients.
iv
Keywords: fear, COVID-19, anxiety, depression, coping, nursing, mental healt
Applied evanescent wave on zinc oxide nanorods coated glass surface for sensing applications / Mohd Hafiz Jali
Get PDFA simple and workable optical fiber sensor was successfully proposed and demonstrated by integrating the microfiber and the glass surface coated with Zinc Oxide (ZnO) nanorods. It exploited the distinctive features of the large evanescent wave of the microfiber and surface absorption capability of the ZnO nanomaterials coated glass surface to couple with the surrounding analyte. An experimental validation was performed to optimize and verify the sensing performance of the proposed structure. ZnO nanorod growth time of 12-hours and microfiber waist diameter of 6 µm provide optimum sensing results towards the changes of humidity concentration level. The diameter of silica fiber was reduced by tapering process using flame brushing technique and the glass surface was coated with ZnO nanorods using hydrothermal synthesis method. A significant response to humidity concentrations level ranging from 35 %RH to 85 %RH has been observed and the output power of the proposed sensor has decreased linearly from -16.32 dBm to -18.68 dBm with linearity of 95.87 %. The sensitivity and the resolution of the ZnO nanorods coated glass improve by a factor of 2.8 and 7.5 respectively, as compared to the uncoated glass substrate. The proposed sensor also demonstrates a good response to formaldehyde concentrations from 0 ppm to 0.18 ppm. The output power of the proposed sensor has reduced linearly from -22.64 dBm to -24.24 dBm with sensitivity and resolution of 9.78 dBm/ppm and 0.0016 ppm respectively. The sensitivity improves by a factor of 3 and the resolution by a factor of 2.5 when the glass surface is coated as compared to uncoated glass surface. It is due to strong chemisorption process and changeable refractive index of the ZnO nanorods coated glass surface. The proposed sensor successfully employs the interaction between the ZnO nanorods surface and the evanescent field from the microfiber which reduce the striving effort in handling the microfiber during the synthesis process and sensing applications. In addition, the performance of the proposed sensor has been further enhanced by incorporating microsphere resonator with diameter of 234 µm on the ZnO nanorods coated glass surface. For humidity sensing, it produces better sensitivity of 0.0748 dBm/%RH and 0.0142 nm/%RH as compared the straight microfiber laid on the ZnO coated glass substrate with 0.0527 dBm/%RH and 0.0097 nm/%RH respectively. The standard deviation and resolution also improve by a factor of 1.7 and 2.4 respectively as compared to the straight microfiber laid on the ZnO nanorods coated glass. While for the formaldehyde sensor, the sensitivity improves by a factor of 1.84 and 1.33 in terms of output power and wavelength shift respectively as compared to straight microfiber laid on the ZnO coated glass substrate. The resolution also was greatly improved by a factor of 1.87 as compared to straight microfiber laid on the ZnO coated glass substrate. It is due to the ultra-high Q factor of microsphere which enhanced interaction between the whispering gallery mode evanescent components with surrounds analyte
The ecology of elephant dung associated dung beetles in Peninsular Malaysia / Thary Gazi
No full textThe loss of large mammals such as Asian Elephants (Elephas maximus) can potentially disrupt the trophic structure for ecosystems that depend on the dung produced by these animals. This can cause a restructuring of the dung beetle community as it may result in less resources for food and breeding and higher intra- and interspecific competition. Dung beetles utilise dung in different manners, and this leads them to be categorised as dwellers, tunnelers or rollers. These categories of beetle likely have different reactions to changes in resource availability. For this study I 1) Designed a method to collect large numbers of dwelling and tunnelling dung beetles, 2) examined the effects of habitat type on the diversity and abundance of elephant dung visiting dung beetles, 3) determined the effects of elephant removal on the community structure of dwelling and tunneling dung beetles and 4) quantified if changes in resource availability affects the phenotype of six common dung beetle species. A novel dung beetle trap, the burrowing interception trap, was designed and the dung beetle collecting performance was compared with conventional pitfall traps. For objectives (2) and (3), dung beetles were sampled from six localities in Peninsular Malaysia, half of which had elephants absent because of human elephant conflict relocations. Both forest edges and forests were sampled to take into account the effects of habitat. Dung beetles were categorised as forest edge or forest species based on their distribution amongst the two habitat types. Between two localities with similar forest structure and elevation but different presence/absence of elephants, I compared intraspecific pronotum sizes of six species of dung beetles. Burrowing interception traps could collect higher abundance, species richness and Shannon diversity but were not effective in collecting roller dung beetles compared to pitfall traps. A total 5413 individuals from 50 tunnelling and dwelling dung beetle species were collected in all localities. Habitat selection of dung beetles played an important role in community assembly, with 10 species categorised as preferring forest edge environments to forests. Forests also had higher abundance and species richness compared to forest edges. Generalised linear models indicated a a positive relationship between the abundance of dwellers and the presence of elephants. At least two species, Megatelus brahminus and Copris numa, were found to be absent when elephants were removed, both were forest edge species. When the intraspecific pronotum widths were examined, two dweller species, Liatongus femoratus and Oniticellus tessellatus, had significant differences in pronotum size, while four tunneler species did not. The loss of elephant dung likely causes a shift from dweller dominated to tunneler dominated communities as an environment with excess resources changes to one of limited and rapidly depleted resources. Aside from extinction, it is possible that some species undergo phenotypic change in order to survive the change in resource availability. This study indicates that the relationship between elephants and dung beetles is a complex interaction that depends on behavioural adaptations of all species and environmental factors
High gain fabry-perot antenna with broadband low radar cross section and deflected beam radiation for stealth platforms / Hassan Umair
No full textAs stealth technology has stood its ground for military/defense deterrence, it has become growingly important to develop antennas compatible with low-observable platforms. Antennas can be huge source of radar backscatter, thereby increasing radar signature of the platform on which it is mounted. This consequently compromises the target’s stealth property. To counter this, many techniques have been adopted to reduce antenna radar cross section (RCS), which include shaping, radar absorbing material (RAM) coatings, frequency selective surface (FSS) radomes/ground-planes, and implementing absorptive electromagnetic band gap (EBG) structures or perfect metamaterial absorbers. In most of these cases, antenna radiation is either deteriorated, or just remains intact. To this end, partially reflecting surfaces (PRSs) integrated with absorptive FSSs in a Fabry-Perot (FP) cavity configuration have been employed above patch antennas, which not only achieve wideband absorption of radar waves, but also enhance antenna’s radiated gain. However, so far, the adoption of phase gradient metasurfaces (PGM) with the absorptive/scattering surfaces, to achieve not only low RCS and high radiated gain, but also antenna beam deflection, has not been explored yet. It can find useful applications such as in side-looking airborne radars (SLARs), satellite communication platforms, base station antennas, pattern decorrelated multiple-input multiple-output (MIMO) antenna, or any military application requiring off-the-horizon communication. In view of this, three FP antennas have been presented in this thesis, realizing following functionalities all in parallel: (1) wideband low monostatic RCS, (2) antenna gain enhancement, and (3) antenna beam deflection. As first objective of the thesis, an FP antenna has been designed employing an absorptive FSS integrated with a dual sided phase gradated PRS. The achieved wideband absorptivity ranges from 5.8-16 GHz (93.57%), for arbitrary polarizations. Peak gain is 11.5 dB at 6.6 GHz, with tilt angle of 13° in the elevation plane. Cavity height is λ/2. As second objective, same configuration has been adopted but with modified gradient implementation. Advantages achieved are the increase of the tilt angle to 32°, and the reduction of cavity height to λ/4. Wideband RCS reduction, from 4-16 GHz (120%), has been achieved. Peak gain is 9.4 dB at 6 GHz. Finally, in third objective, to achieve RCS reduction, instead of adopting resistive FSS, artificial magnetic conductor (AMC) based approach has been implemented leveraging reflection phase cancellation principle over a wideband. Advantage over previous approaches is the lesser complexity and cost, as no resistor soldering/stuffing is required. The checkerboard AMC surface has been integrated with PGM, achieving wideband RCS reduction from 4-13 GHz (105.8%), peak gain of 12 dB at 7 GHz, and beam deflection of 60°. Cavity height is 0.33λ. Afterwards, the antenna’s modified version has also been presented, in which the AMC interfaces of destructive interference have been ignored in one of the principal axes (y-axis). The result is a 41% reduction of cavity’s aperture size; however, the RCS reduction bandwidth, which is still wide, is asymmetric for orthogonal polarizations of the incident wave. For the three objectives, detailed simulation/measurement results have been presented, along with performance comparisons with previous literature
Doped-magnesium manganese oxide cathode for rechargeable magnesium batteries / Nurhidayu Harudin
No full textMagnesium has numerous good characteristics that make it attractive as an electrode material for rechargeable batteries. There are many advantages of Magnesium (Mg) such as available in abundance, ease of handling, low toxicity and environmental friendly. Due to its benefits, magnesium ion battery can be considered as an alternative to lithium in future. In the present work, the improvement electrochemical properties of magnesium-based cathode material, MgMn2O4 was done by adding calcium (Ca) and strontium (Sr) as dopant i.e MgMn2-xCaxO4 and MgMn2-xSrxO4. These materials with compositions of x=0.1,0.2,0.3,0.4,0.5 were synthesized by self-propagating combustion method using citric acid as a reducing agent. The precursors obtained were annealed at temperatures of 700C and 800C for 24 hours. The electrochemical studies were performed by using Linear Sweep Voltammetry (LSV) and Cyclic Voltammetry (CV) to determine electrochemical stability and properties of the prepared samples using 1M of magnesium trifluoromethane sulfonate Mg(CF3SO3)2 electrolyte. The magnesium ion cells were fabricated using the optimized cathode materials and the cell performances were be studied by galvanostatic charge-discharge test. At temperature 700°C, the specific capacity obtained from MgMn1.8Ca0.2O4 and MgMn1.8Sr0.2O4 at first cycle was 60 mAh g-1 and 40 mAh g-1 respectively. At temperature 800°C, the fabricated cells conveyed the specific capacity of 138 mAh g-1 and 160 mAh g-1 for Ca and Sr doped samples respectively. Therefore, it can be stated that both Ca and Sr doped systems of MgMn2O4 based cathode materials enhances a good electrochemical properties thus improving the battery performances
Microwave-assisted synthesis of ZnO/TiO2/Ag nanocomposites as alternative antimicrobials / Priyadarshini Sakthi Mohan
No full textIn the present study, antimicrobial metal and metal oxide nanomaterials were synthesised using aqueous extracts of the medicinal plants, Cissus quadrangularis stem (CQS) and Morinda citrifolia (MCF) fruit. Two different sizes (15.9 nm, 24.2 nm) of silver/silver chloride nanoparticles (Ag/AgClNPs) were synthesised using CQS extract under microwave irradiation. Titanium oxide nanoparticles (TiO2NPs) were also synthesised by microwave irradiation of CQS extract followed by calcination at 450°C for 3 h. The synthesised nanoparticles were characterised by Fourier-transform infrared spectroscopy, X-ray diffraction analysis, high-resolution transmission electron microscopy and zeta potential analysis. The bioactivities of 15.9 nm, 24.2 nm Ag/AgClNPs and TiO2NPs against human nosocomial Gram-positive and Gram-negative bacterial pathogens (Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus NCTC 6571, Bacillus subtilis ATCC 23857, and Escherichia coli ATCC 25922) in liquid media were analysed. The antibacterial study results demonstrated higher bactericidal activity of Ag/AgClNPs and negligible activity of TiO2NPs against human nosocomial pathogens. Further, metabolic activity and confocal viability assay results provided strong evidence that the 15.9 nm Ag/AgClNPs inhibited the bacterial pathogens better than the 24.2 nm Ag/AgClNPs and TiO2NPs. The bioactivity of TiO2NPs was enhanced under ultraviolet (UV) illumination where it showed significant bactericidal activity of tested bacterial pathogens under UV, (365 nm) light. Photoactivation generated holes (h+) and electrons (e−) on the surface of the TiO2NPs, inducing hydroxyl (•OH) and superoxide free radicals (O2−•) reactive oxygen species (ROS) on the bacterial surface. The cytotoxicities of the synthesised Ag/AgClNPs and TiO2NPs were studied towards human A549 adenocarcinomic alveolar basal epithelial cell line and RAW 264.7 macrophage cells. Anticancer activity of both 15.9 nm Ag/AgClNPs and 24.2 nm Ag/AgClNPs displayed the IC50 values at 85 μg/mL and 90 μg/mL against A549 lung cancer cell lines while RAW 264.7 macrophage cells expressed the IC50 values at 130 μg/mL and 140 μg/mL respectively. Our results suggested that the synthesised Ag/AgClNPs can be used to develop novel antimicrobial and anticancer formulations. Secondly, for the first time, successful fabrication of ternary ZnO/TiO2/Ag nanocomposites (NCs) consisting of zinc oxide (ZnO), titanium oxide (TiO2) and silver (Ag) nanoparticles (NPs) was achieved using MCF extract and their respective precursor solutions under microwave irradiation. This ternary NCs material demonstrated enhanced bactericidal effect towards the nosocomial bacterial pathogens compared to the binary TiO2/Ag, Ag and TiO2 alone. In-vitro cytotoxicity results of the synthesised ZnO/TiO2/AgNCs on RAW 264.7 macrophages and A549 cell lines revealed a negative role in cytotoxicity but contributed astoundingly towards antimicrobials as compared to Ag alone and binary Ag/TiO2. This study shows that the resultant ternary metal/bi-semiconductor NC may provide a therapeutic strategy for eradicating bacterial pathogens without affecting the healthy mammalian cells. Lastly, the comparative study of the synthesised NPs and NCs was carried out. The results suggested that the ZnO/TiO2/AgNCs synthesised using MCF extract possessed more significant antibacterial activity and high biocompatibility than the AgNPs, Ag/AgClNPs, TiO2NPs, TiO2/AgNCs
Spotting events in football videos with a combination of two-stream convolutional neural network and dilated recurrent neural network / Behzad Mahaseni
No full textIn this research, we address the problem of event detection and localization in football (soccer) videos. While the problem of event detection in videos is itself a research problem, event detection in sports, especially in football, has an important commercial impact as well. Football is played by more than 250 million players in 200+ nations. In addition, it has the highest television audience in sport. This makes football the most popular sport in the world. Considering the advancement in streaming technologies on mobile platforms, it is important to develop efficient and fast processing algorithms for thousands of videos captured and stored in the cloud. Unlike images, videos provide additional temporal information. While this additional information is helpful, it also makes the reasoning more challenging. On one hand, from the local correlation between adjacent frames, it is possible to identify the short-range correlation between player movements. On the other hand, one can identify the mid-range and long-range correlation between events that are seconds away from each other. One important challenge in analyzing long videos is how to consider all range of correlations (short - long) between video frames. Localizing (temporal segmentation) events in a football video is a challenging problem. While the general problem of temporal segmentation in videos have been extensively addressed in the literature, to the best of our knowledge this work is the among the first to address the event localization problem in “long” football videos using end-to-end deep learning techniques. Football videos are long and the correlation between frames in the video ranges from short to long. To model various range of correlations in football videos, we propose to use a combination of two-stream CNNs and dilated RNNs with LSTM cells, to capture short-range and long-range correlations. Our experimental result shows 5.4% - 11.4% accuracy improvement compared to the state of the art and the baselines for the problem of spotting in long videos presented in the largest football dataset available for research community (i.e., SoccerNet)