Road distress results in high maintenance costs. However, increased understandings of asphalt behaviour and properties coupled with technological developments have allowed paving technologists to examine the benefits of introducing additives and modifiers. As a result, polymers have become extremely popular as modifiers to improve the performance of the asphalt mix. This study investigates the performance characteristics of epoxidized natural rubber (ENR)-modified hot-mix asphalt. Tests were conducted using ENR-asphalt mixes prepared using the wet process. Mechanical testing on the ENR-asphalt mixes showed that the resilient modulus of the mixes was greatly affected by testing temperature and frequency. On the other hand, although rutting performance decreased at high temperatures because of the increased elasticity of the ENR-asphalt mixes, fatigue performance improved at intermediate temperatures as compared to the base mix. However, durability tests indicated that the ENR-asphalt mixes were slightly susceptible to the presence of moisture. In conclusion, the performance of asphalt pavement can be enhanced by incorporating ENR as a modifier to counter major road distress.
The incidence of rhinolith is by far very low compared to the nasal foreign bodies, especially in adult. Foreign body (FB) in the nostril will lead to unilateral nasal symptom which can start with nasal obstruction or discomfort. In younger children, they may miss to report the problem to the parents but, later on, the FB will manifest itself with unilateral nasal discharge, which at most of the time fouls smells. We report a case of a healthy adult female who presented with unilateral foul smelly nasal discharge which later was diagnosed as rhinolith, with rubber-tip pencil eraser as the nidus of calcification.
The present study is unique in the Malaysian context on two counts; first, it employs for the first time a functional group approach (groups based on occupational or economic activity) in the assessment of community nutritional status. Second, the study provides on a nationwide-sampling basis, information on total blood cholesterol (TC) levels in rural children (7.0-12.9 years; n = 1921) and adolescents (13.0-17.9 years; n = 753) which were hitherto unavailable. Total blood cholesterol measurements were performed on 7184 subjects ranging from 7 to 75-years-old (males = 3151; females = 4033) from households in 69 rural villages and seven estates in peninsular Malaysia, which were based on selected multistage random sampling according to the household's involvement in the following economic activities: rice farming, rubber smallholding, coconut smallholding, fishing and employment in estates. In all functional groups, TC values increased with age and there was a distinct gender effect, namely females had higher TC values than males throughout the age spectrum analyzed. Mean TC levels for children and adolescents were in the range 3.85-4.37 mmol/L, rising markedly during adulthood to an overall mean of 4.91 ± 1.13 mmol/L for men and 5.17 ± 1.11 mmol/L for women. In adults (>= 18.0 years), there was marked disparity in mean TC values among the functional groups; males and females from rice households had the lowest mean TC values (4.58 and 4.99 mmol/L, respectively). Individuals at 'high risk' (TC > 6.20 mmol/L) averaged 16.0% in women and 11.6% in men, with women from the fishing, rubber and coconut households particularly affected (17.1-21.1%). When compared to earlier rural TC data reported for closely similar rural communities in the peninsula, the present findings suggest a 'hypercholesterolemic shift' approximating 0.39 mmol/L (15 mg/dL) in the adult population; however, this was not apparent in the children and adolescents from these rural communities.
The data presented is part of the findings from a four-year collaborative research project between Universiti Putra Malaysia, the Institute for Medical Research and the Ministry of Health Malaysia. The project assessed the nutritional status of the major functional groups in Peninsular Malaysia. Mukim Sayong and Pulau Kemiri in the District of Kuala Kangsar, Perak were two of the subdistricts selected to represent small rubber holdings in Peninsular Malaysia. This paper attempts to analyse the socio-economic profile of the households and the nutritional status of children below 9 years of age. A total of 307 households were studied. Approximately 63% of the households were involved in rubber activities and the majority of them were hired tappers. The average monthly income of the households was RM467 and the income ranged between RM30 to RM2120. Based on the per capita poverty line income of RM84.38, it was found that 14.1% of the households earned less than RM42.19, which can be considered as hard-core poor, while 32.7% were poor (monthly per capita income between RM42.19 and RM84.38). Slightly more than half (52.7%) earned income above the poverty line. The average family size was 4.5, ranging from 1 through to 16. The majority of the heads of households (56.6%) had between 3 and 6 years of education, and 14.5% did not receive any formal education. The prevalence of stunting among children 0-5 years of age was 26%, while 31.5% were underweight and 3.8% wasted. Among children aged between 5 and 9 years, almost the same pattern of nutritional status was noted. The overall percentages of stunting, underweight and wasting among these children were 29.2%, 26.1% and 0.62%, respectively. Analysis on nutritional status according to income level showed a noticeable difference in the prevalence of malnutrition in children above and below the poverty line income. The Student's t-test indicated significant differences in weight-for-age and weight-for-height between the two poverty line income for children below 5 years of age. Pearson's correlation coefficient showed a significant correlation between height-for-age with household size (r = -0.26, p<0.05), and monthly per capita income with weight-for-height (r = 0.25, p<0.05). There was a highly significant correlation between acreage of land cultivated and weight-for-height (r = 0.42, p<0.01), and weight-for-age (r = 0.25, p<0.05). The findings indicated the influence of socio-economic factors on the nutritional status of children.
Coastal waters in South Johore, Malaysia are polluted to various degrees. The major pollution sources are domestric wastes from human settlements, agro-based wastes from palm oil mills and rubber processing factories, industrial effluents from industrial estates and discharges from animal farms. These pollution problems have adversely affected resources such as fisheries, recreational potential as well as the general aesthetic quality of the coastal environment particularly the Inner Johore Strait. Hence proper management and control measures are urgently needed to protect and further enhance the water quality to ensure environmentally sustainable development. This study examines various management options to control the pollution in the Inner Johore Strait. The options involve partial opening as well as complete removal of the Causeway to improve the tidal flow for more effective dilution and dispersion of pollutants. Computer simulation models are used to assess the impacts of the proposed options.
With increased awareness on the importance of gloves arising from the COVID-19 pandemic, people are expected to continue using them even after the pandemic recedes. This scenario in a way increased the rubber solid waste disposal problem; therefore, the production of biodegradable gloves may be an option to overcome this problem. However, the need to study the shelf life of biodegradable gloves is crucial before commercialization. There are well-established models to address the failure properties of gloves as stated in the American Society for Testing and Material (ASTM) D7160. In this study, polysaccharide-based material-filled natural rubber latex (PFNRL) gloves, which are biodegradable gloves, were subjected to an accelerated aging process at different temperatures of 50-80 °C for 1-120 days. Prediction models based on Arrhenius and shift factors were used to estimate the shelf life of the PFNRL gloves. Based on the results obtained, the estimated time for the PFNRL gloves to retain 75% of their tensile strength at shelf temperature (30 °C) based on Arrhenius and shift factor models was 2.8 years. Verification on the activation energy based on the shift factor model indicated that the shelf life of PFNRL gloves is 2.9 years, which is only a 3.6% difference. The value obtained is aligned with the requirement in accordance with ASTM D7160, which states that only up to a maximum of 3 years' shelf life is allowed for the gloves under accelerated aging conditions.
Adhesives serve many functions in daily life, starting from sticking envelopes to rejoining broken
materials. Adhesives are usually developed for a specific purpose and the performances can vary
according to their specific end-use. Most of the commercially available adhesives comprised nonrenewable or petroleum derived raw materials. Thus, in order to mitigate negative impact of using nonrenewable material as the raw material for adhesives, a new type of adhesive containing epoxidised
natural rubber (NR) latex is developed. Epoxidised NR latex adhesive was initially prepared and pigment
was subsequently added to produce desired colours of the adhesive. Hence, the newly developed adhesive
can serve as adhesive and also as paint for art. The adhesives were characterised and the results indicated
that they were free from heavy metal contents and volatile organic compounds (VOCs). The adhesives
exhibited comparable odour concentration to commercial synthetic-based adhesive. In terms of toxicity
level, the adhesive developed exhibited low acute oral toxicity. Peel adhesion test of A4 and drawing
papers on stainless steel and glass substrates, opacity and glossiness were also investigated in the present
study. This coloured adhesive is deemed to support the STEM (science, technology, engineering and
mathematics) learning by indirectly imparting polymer science and technology in art education and
further promotes creative learning among school children. The adhesive is also derived from renewable
material rendering it more environmentally friendly.
Objective: To evaluate feasibility of hand gloves as a rubber dam isolation alternative, in respect of physical properties. Materials and Methods: A randomized controlled trial study design was used. Three types of gloves were tested with two types of a rubber dam used as the control group. Cut-out pattern of dumb-bell shapes were made from 35 samples for each type of groups and tensile strength were tested using Universal Testing Machine and the Trapezium X software. All tests for physical requirements were performed in accord-ance with American Society for Testing and Materials D412, Standard Test Methods for Vulcanized Rubber and Thermoplastic Rubbers and Thermoplastic Elastomers-Tension. Findings were analyzed by analysis of vari-ance (ANOVA) and differences were compared using a Tukey-Kramer interval calculated at the 0.05 signifi-cance level. Results: Heavy gauge rubber dam has the highest Mean (calculated at the 0.05 significance level) except for maximum stress calculated at entire area. Medium-gauge rubber dam has significantly higher tensile strength (44.5075 N/mm2) when compared to heavy-gauge rubber dam (35.7787 N/mm2) although it was 0.09mm thinner. Discovery 2020 Powder Free Latex Examination Gloves with tensile strength value of 28.5922 N/mm2 (±3.27366) is more than the minimum requirement specified by American Federal Specification ZZ-R90B Rubber Dam (Dental, 1985) (4000 pounds per square inch or 27.6 N/mm2). For all variable tested, all groups are significantly different from each other. The mean square between the groups was quite large. Conclusion: This study shows that there are significant differences between the physical strength of latex gloves when com-pared to rubber dam. However, the comparison between thickness and tensile strength among various rubber dam, did not correspond proportionately. Only one type of rubber gloves met the minimum requirement but that is just one aspect. In view of these mixed results, more research is needed before we can conclude that it is feasable that we use hand gloves to replace rubber dam.
Aedes albopictus larvae obtained from different types of agricultural and non-agricultural localities in Peninsular Malaysia were subjected to several larvicides at World Health Organization (WHO) recommended dosages. Upon 24 h of WHO larval bioassay using two organochlorines and six organophosphates, high resistance against dichlorodiphenyltrichloroethane (DDT), temephos, chlorpyrifos and bromophos were demonstrated among all larval populations. Aedes albopictus larvae from both paddy growing areas (92.33% mortality) and rubber estates (97.00% mortality) were moderately resistant to dieldrin while only Ae. albopictus larvae from dengue prone residential areas (89.00% mortality) showed high resistance against dieldrin. All Ae. albopictus larval populations also developed either incipient or high resistance to both malathion (33.67%-95.33% mortality) and fenitrothion (73.00%-92.67% mortality). Only Ae. albopictus larvae from fogging-free residential areas that were tolerant to fenthion (97.33% mortality), whereas Ae. albopictus larvae from dengue prone residential areas were highly resistant to the same organophosphate (88.33% mortality). Cross resistance between intraclass and interclass larvicides of organochlorines and organophosphates were also exhibited in this study. The present study provided baseline data on various susceptibility levels of Ae. albopictus larval populations from different types of agricultural and non-agricultural localities against organochlorines and organophosphates at WHO recommended dosages. Nevertheless, further susceptibility investigations are suggested using revised doses of larvicides established from the local reference strain of Ae. albopictus to prevent the underestimation or overestimation of insecticide resistance level among Ae. albopictus field strains of larvae.
The impacts of rubber variations (clonal, seasonal, and pre-treatment) were investigated to assess changes in the composition of volatile organic compounds (VOCs) emitted during rubber processing. VOC emissions from 14 different rubber types were evaluated by headspace micro-chamber (μ-TEC) extraction coupled with gas chromatography-mass spectrometry (GC-MS). Headspace extracted at 120 °C, which is equivalent to the drying temperature during rubber processing, revealed a significant number of odorants in terms of concentrations as well as odorant type. Volatile fatty acids (VFAs) such as acetic, propanoic, butanoic, pentanoic and hexanoic acids, were frequently detected at concentrations greater than their odour detection thresholds. Other odorous compounds including trimethylamine, p-cresol, butanone, indole, and phenol, were also detected. Emissions collected at ambient conditions represent odorants released during material storage (or maturation) and were dominated by benzene derivatives followed by ketones, aldehydes, esters, and acids. Emission composition during storage appeared to be governed by specific rubber properties such as protein and rubber moisture content. Seasonal variations revealed greater impacts on the concentration of VOCs for all studied clones, compared to pre-treatment variations, suggesting that the VOCs composition was seasonally dependent and may represents the 'potential' emissions from rubber as they are processed. A combination of sensorial and analytical measurements were used to produce odour wheels which may be used as tool to identify key malodours in onsite rubber processing. The linking of odours and odorants can facilitate communication between receptors (the public) and plant operators inorder to minimise odour impact and develop effective abatement and on-site management practices.
Liquid natural rubber (LNR) was functionalized into liquid epoxidized natural rubber (LENR) and hydroxylated LNR (LNROH)
via oxidation using a Na2
WO4
/CH3
COOH/H2
O2
catalytic system. Microstructures of LNR and functionalized LNRs
were characterized using Fourier Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopies. The
effect of CH3
COOH, H2
O2
, Na2
WO4
, reaction time and temperature. reaction time and temperature on epoxy content were
investigated. LNR-OH was obtained when oxidation reaction was conducted at a longer reaction time, higher temperature
or excess amount of catalyst. Thermogravimetric analysis (TGA) reported the thermal behavior of functionalized LNRs.
Molecular weight and polydispersity index (PDI) were determined using gel permeation chromatography (GPC).
Ammonium-enriched skim latex serum - used for absorption of contaminating ammonia gas - when composted with other rubber tree wastes, is promising as a good compost. The objective of this research was to utilize ammonium-enriched skim latex serum (S) as a raw composting ingredient after being combined with para sawdust (W1) and para rubber leaves (W2). Several ratios of S, W1 and W2 were experimented in a 15L composting vessel to determine the most effective compost. The best ratio was found to be 3:1:3 by weight at 12-day retention. The modified 30 L composting reactor employed with the derived optimum mixing conditions yielded N, P and K of 2.40, 1.51 and 14.84 %w/w. The growth of Brassica alboglabra after application of this compost combined with a chemical fertilizer generated the highest fresh weight (4.48 g/plant). Thus, compost from these wastes could be used as a fertilizer and logically should contribute to cost saving of waste disposal.
Rigidoporus microporus, Ganoderma philippii, and Phellinus noxius are root rot rubber diseases and these fungi should be kept under control with environmentally safe compounds from the plant sources. Thus, an antifungal compound isolated from Catharanthus roseus was screened for its effectiveness in controlling the growth of these fungi. The antifungal compound isolated from C. roseus extract was determined through thin layer chromatography (TLC) and nuclear magnetic resonance (NMR) analysis. Each C. roseus of the DCM extracts was marked as CRD1, CRD2, CRD3, CRD4, CRD5, CRD6, and CRD7, respectively. TLC results showed that all of the C. roseus extracts peaked with red colour at Rf = 0.61 at 366 nm wavelength, except for CRD7. The CRD4 extract was found to be the most effective against R. microporus and G. philippii with inhibition zones of 3.5 and 1.9 mm, respectively, compared to that of other extracts. These extracts, however, were not effective against P. noxius. The CRD4 extract contained ursolic acid that was detected by NMR analysis and the compound could be developed as a biocontrol agent for controlling R. microporus and G. philippii. Moreover, little or no research has been done to study the effectiveness of C. roseus in controlling these fungi.
Monitoring of land use change is crucial for sustainable resource management and development planning. Up-to-date land use change information is important to understand its pattern and identify the drivers. Remote sensing and geographic information system (GIS) have proven as a useful tool to measure and analyze land use changes. Recent advances in remote sensing technology with digital image processing provide unprecedented possibilities for detecting changes in land use over large areas, with less costs and processing time. Thus, the objective of this study was to assess the land use changes in upper Prek Thnot watershed in Cambodia from 2006 until 2018. Geospatial tools such as remote sensing and GIS were used to process and produce land use maps from Landsat 5 TM, Landsat 7 ETM+ and Landsat 8. The post-classification comparison was conducted for analysing the land use changes. Results show forest area was greatly decreased by 1,162.06 km2 (33.67%) which was converted to rubber plantation (10.55 km2 ), wood shrub (37.65 km2 ), agricultural land (1,099.71 km2 ), built-up area (17.76 km2 ), barren land (3.65 km2 ), and water body (14.69 km2 ). Agricultural land increased by 1,258.99 km2 (36.48%), while wood shrub declined by 161.88 km2 (4.69%). Rubber plantation, built-up area, barren land, and water bodies were increased by 10.55 km2 (0.31%), 33.64 km2 (0.97%), 4.87 km2 (0.14%) and 15.89 km2 (0.46%), respectively. The decrease of forest and wood shrub had resulted due to population growth (1.8% from 2008 to 2019) and land conversion for agricultural purposes. Hence, this study may provide vital information for wise sustainable watershed’s land management, especially for further study on the effect of land use change on runoff in this area.
Malaria is still a very real threat to health in S.E. Asia including Malaysia. While there has been a dramatic fall in the number of cases and also the number of deaths from the disease in Malaysia cases are still occurring and there has actually been a rise in the number of deaths in the past year. Parts of Perak and the East Coast states are still high risk areas in Peninsular Malaysia. While 95 percent of the population of Peninsular Malaysia is now malaria-free there has also been a concomitant loss of herd immunity which means that if a non-immune person contracts falciparum malaria he stands a greater chance of a fatal outcome. Doctors and other health personnel should be more malaria conscious and make a practice of making blood films of all cases of fever. This is especially important in the rural areas and Estate Hospital Assistants must be encouraged to look for malaria parasites in their fever patients. The younger generation of EHAs have little experience of malaria and a definite policy of education to bring them up to date in antimalarial work and microscopic detection of the parasite should be under taken by the industry. Some problems of chemotherapy and drug resistance are discussed.
The widespread use of magnetorheological elastomer (MRE) materials in various applications has yet to be limited due to the fact that there are substantial deficiencies in current experimental and theoretical research on its microstructural durability behavior. In this study, MRE composed of silicon rubber (SR) and 70 wt% of micron-sized carbonyl iron particles (CIP) was prepared and subjected to stress relaxation evaluation by torsional shear load. The microstructure and particle distribution of the obtained MRE was evaluated by a field emission scanning electron microscopy (FESEM). The influence of constant low strain at 0.01% is the continuing concern within the linear viscoelastic (LVE) region of MRE. Stress relaxation plays a significant role in the life cycle of MRE and revealed that storage modulus was reduced by 8.7%, normal force has weakened by 27%, and stress performance was reduced by 6.88% along approximately 84,000 s test duration time. This time scale was the longest ever reported being undertaken in the MRE stress relaxation study. Novel micro-mechanisms that responsible for the depleted performance of MRE was obtained by microstructurally observation using FESEM and in-phase mode of atomic force microscope (AFM). Attempts have been made to correlate strain localization produced by stress relaxation, with molecular deformation in MRE amorphous matrix. Exceptional attention was focused on the development of molecular slippage, disentanglement, microplasticity, microphase separation, and shear bands. The relation between these microstructural phenomena and the viscoelastic properties of MRE was diffusely defined and discussed. The presented MRE is homogeneous with uniform distribution of CIP. The most significant recent developments of systematic correlation between the effects of microstructural deformation and durability performance of MRE under stress relaxation has been observed and evaluated.
Introduction: This study aimed to (i) determine rapid weight loss (RWL) practices among Malaysian elite combat sports athletes and (ii) examine the relationship between the characteristics of athletes, self-reported history of weight loss, perceived influence on weight loss and RWL practices.
Methods: This was a cross-sectional study conducted at the Malaysian National Sports Institute among elite combat sports athletes (n=40) recruited via a convenience sampling method. The athletes completed a self-administered validated Rapid Weight Loss Questionnaire. Each response was provided a score and the total RWL score corresponded to the aggressiveness of weight management methods. Partial correlations were used to assess the relationships between total RWL score and independent variables.
Results: The prevalence of RWL among the athletes was high (92.5%). Training with rubber or plastic suits (62.2%) and meal-skipping (27.0%) were the most common RWL techniques practised by the respondents. Aggressive weight-cutting as depicted by a higher total RWL score that correlated with most weight ever lost, duration taken to lose weight, influence of training colleagues and coaches, BMI, current weight and post-competition weight regain (all p
A case of mucosal burn during the placement of fissure sealant on the first permanent molars of a 9-year-old Malay boy is presented. The erythematous lesion with accompanying burning sensation appeared a few minutes after the etching liquid, containing 37% by weight phosphoric acid, had accidentally come into contact with the buccal mucosa on the right side of the angle of the mouth. The mucosa showed complete healing after one week. The use of rubber dam for tooth isolation while doing fissure sealant is essential to avoid accidental contact of potentially caustic chemicals, such as the phosphoric acid etchant, with the oral mucosa as it can result in mucosal burns.
This paper attempts to integrate both a forward and reverse supply chain to design a closed-loop supply chain network (CLSC). The problem in the design of a CLSC network is uncertainty in demand, return products and the quality of return products. Scenario analyses are generated to overcome this uncertainty. In contrast to the existing supply chain network design models, a new application of a CLSC network was studied in this paper to reduce waste. A multi-product, multi-tier mixed integer linear model is developed for a CLSC network design. The main objective is to maximize profit and provide waste management decision support in order to minimize pollution. The result shows applicability of the model in the tire industry. The model determines the number and the locations of facilities and the material flows between these facilities.