Displaying publications 1 - 20 of 747 in total

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  1. AHMAD SHAHIR BIN JAMALUDIN, ABDULLAH BIN YASSIN
    Sains Malaysiana, 2013;42:1727-1733.
    Invention of milling combined laser sintering system (MLSS) is able to reduce the mould manufacturing time and improve the mould accuracy. Thus, more study is needed to increase the understanding for the laser sintered material machining characteristic to gain benefit from the invention of MLSS. This paper clarified the analysis of laser sintered material machinability with the application of Finite Element Method (FEM). Mild steel AISI1055 was applied in developing the Finite Element model in this study due to its popularity in machinability test and adequate level of data availability. 2D orthogonal cutting was employed on edge design tools with updated Lagrangian coupled thermo mechanical plane strain model. Adaptive meshing, tool edge radius and various types of friction models were assigned to obtain efficient simulations and precise cutting results. Cutting force and cutting-edge temperature estimated by Finite Element Method are validated against corresponding experimental values by previous researchers. In the study, cutting force increases when radial depth increases and lowest error acquired when the shear friction factor of 0.8 was applied. Machining simulation for laser sintered materials estimated lower cutting force compared with mild steel AISI1055 due to lower Young modulus. Higher cutting temperature estimated for machining simulation laser sintered material compared with machining simulation mild steel AISI1055 due to its low thermal conductivity.
    Matched MeSH terms: Hot Temperature
  2. Abbas Ali M, Bamalli Nouruddeen Z, Ida I. Muhamad, Abd Latip R, Hidayu Othman N
    Sains Malaysiana, 2014;43:1189-1195.
    The aim of this study was to evaluate on how heat treatments by microwave oven may affect the oxidative degradation of sunflower oil (SFO) and its blend with palm olein (Po). The blend was prepared in the volume ratio of 40:60 (Po: SFO, PSF). The samples were exposed to microwave heating at medium power setting, for different periods. In this study, refractive index, free fatty acid content, peroxide value, p-anisidine value, total oxidation (Tomx), specific extinction, viscosity, polymer content, polar compounds and food oil sensor value of the oils all increased, whereas iodine value and C 18:21C16:0 ratio decreased as microwave heating progressed. Microwave heating temperature increased with increasing heating time and longer heating times resulted in a greater degree of oil deterioration. The percentage of linoleic acid tended to decrease, whereas the percentage of palmitic acid increased. The effect of adding PO to SFO on the formation of free fatty acids and conjugated dienes during microwave treatment was not significant (p< 0.05). No significant differences in food oil sensor value was observed between SFO and PSF. Based on the most oxidative stability criteria, it can be concluded that the microwave heating caused the formation of comparatively lower amounts of oxidation products in PSF compared to SFO, indicating a lower extent of oxidative degradation of PSF.
    Matched MeSH terms: Hot Temperature
  3. Abbas Ali M, Anowarul Islam M, Othman NH, Noor AM
    J Food Sci Technol, 2017 Dec;54(13):4335-4343.
    PMID: 29184239 DOI: 10.1007/s13197-017-2904-1
    The oxidative stability and fatty acid composition of groundnut seed oil (GSO) exposed to microwaves were evaluated during heating at 170 °C. During heating, the oxidative indices such as free fatty acid, peroxide value, p-anisidine value, TOTOX, thiobarbituric acid value, specific extinctions, and color value were increased. The increments were found to be higher in unroasted seed oils compared to roasted ones indicating lower release of lipid oxidation products in roasted GSO. After 9 h heating, the relative content of polyunsaturated fatty acid (PUFA) decreased to 89.53% and that of saturated fatty acid (SFA) increased to 117.46% in unroasted sample. The relative content of PUFA decreased to 92.05% and that of SFA increased to 105.76% in 7.5 min roasted sample after 9 h of heating. However, the roasting process slowed down the oxidative deterioration of PUFA. With increased heating times, an appreciable loss was more apparent in the triacylglycerol species OLL and OOL in unroasted samples compared to roasted ones. In FTIR, the peak intensities in unroasted samples were markedly changed in comparison with roasted samples during heating. The roasting of groundnut seed prior to the oil extraction reduced the oxidative degradation of oil samples; thereby increasing heat stability.
    Matched MeSH terms: Hot Temperature
  4. Abbasiliasi S, Tan JS, Ibrahim TAT, Ramanan RN, Kadkhodaei S, Mustafa S, et al.
    J Food Sci Technol, 2018 Apr;55(4):1270-1284.
    PMID: 29606741 DOI: 10.1007/s13197-018-3037-x
    This paper deliberates the modelling and validation of bacteriocin-like inhibitory substance (BLIS) secretion by Pediococcus acidilactici Kp10 at different agitation speeds in a stirred tank bioreactor. A range of models namely the re-parameterised logistic, Luedeking-Piret and maintenance energy were assessed to predict the culture performance of the said bacterium. Growth of P. acidilactici Kp10 was enhanced with increased agitation speed up to 600 rpm while BLIS secretion was maximum at 400 rpm but decreased at higher agitation speed. Growth of P. acidilactici aptly subscribed to the re-parameterised logistic model while BLIS secretion and lactose consumption fitted well with the Luedeking-Piret model. The models revealed a relationship between growth of the bacterium and BLIS secretion. Bacterial growth and BLIS secretion were largely affected by the agitation speed of the stirred tank bioreactor which regulated the oxygen transfer to the culture. BLIS secretion by P. acidilactici Kp10 was however enhanced in oxygen-limited culture. The study also assessed BLIS from the perspective of its stability when subjected to factors such as temperature, pH and detergents. Results showed that BLIS produced by this strain was not affected by heat (at 25-100 °C for 20 min and at 121 °C for 15 min), surfactant (Tween 40, 60 and 80 and urea), detergents (up to 1% SDS), organic solvents (50% each of acetone, methanol and ethanol) and stable in a wide range of pH (2-10). The above information are pertinent with reference to commercial applications of this bacterial product in food manufacturing which invariably involve various sterilization processes and subjected to a wide pH range.
    Matched MeSH terms: Hot Temperature
  5. Abd Halim AA, Zaroog MS, Kadir HA, Tayyab S
    ScientificWorldJournal, 2014;2014:824768.
    PMID: 24977228 DOI: 10.1155/2014/824768
    Effect of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) on acid-denatured Bacillus licheniformis α -amylase (BLA) at pH 2.0 was investigated by far-UV CD, intrinsic fluorescence, and ANS fluorescence measurements. Addition of increasing HFIP concentrations led to an increase in the mean residue ellipticity at 222 nm (MRE 222 nm) up to 1.5 M HFIP concentration beyond which it sloped off. A small increase in the intrinsic fluorescence and a marked increase in the ANS fluorescence were also observed up to 0.4 M HFIP concentration, both of which decreased thereafter. Far- and near-UV CD spectra of the HFIP-induced state observed at 0.4 M HFIP showed significant retention of the secondary structures closer to native BLA but a disordered tertiary structure. Increase in the ANS fluorescence intensity was also observed with the HFIP-induced state, suggesting exposure of the hydrophobic clusters to the solvent. Furthermore, thermal denaturation of HFIP-induced state showed a non-cooperative transition. Taken together, all these results suggested that HFIP-induced state of BLA represented a molten globule-like state at pH 2.0.
    Matched MeSH terms: Hot Temperature
  6. Abdollahi A, Pradhan B
    Sensors (Basel), 2021 Jul 11;21(14).
    PMID: 34300478 DOI: 10.3390/s21144738
    Urban vegetation mapping is critical in many applications, i.e., preserving biodiversity, maintaining ecological balance, and minimizing the urban heat island effect. It is still challenging to extract accurate vegetation covers from aerial imagery using traditional classification approaches, because urban vegetation categories have complex spatial structures and similar spectral properties. Deep neural networks (DNNs) have shown a significant improvement in remote sensing image classification outcomes during the last few years. These methods are promising in this domain, yet unreliable for various reasons, such as the use of irrelevant descriptor features in the building of the models and lack of quality in the labeled image. Explainable AI (XAI) can help us gain insight into these limits and, as a result, adjust the training dataset and model as needed. Thus, in this work, we explain how an explanation model called Shapley additive explanations (SHAP) can be utilized for interpreting the output of the DNN model that is designed for classifying vegetation covers. We want to not only produce high-quality vegetation maps, but also rank the input parameters and select appropriate features for classification. Therefore, we test our method on vegetation mapping from aerial imagery based on spectral and textural features. Texture features can help overcome the limitations of poor spectral resolution in aerial imagery for vegetation mapping. The model was capable of obtaining an overall accuracy (OA) of 94.44% for vegetation cover mapping. The conclusions derived from SHAP plots demonstrate the high contribution of features, such as Hue, Brightness, GLCM_Dissimilarity, GLCM_Homogeneity, and GLCM_Mean to the output of the proposed model for vegetation mapping. Therefore, the study indicates that existing vegetation mapping strategies based only on spectral characteristics are insufficient to appropriately classify vegetation covers.
    Matched MeSH terms: Hot Temperature*
  7. Abdul Hannan Damahuri, Hassan Mohamed, Abdul Aziz Mohamed
    MyJurnal
    Thorium is a fertile material that can undergo transmutation for it to become a fissile material,
    uranium-233. The fissile material can go through a fission process in order to generate heat energy
    and eventually electricity. Most nuclear reactors use uranium as their fission source. The use of
    thorium as nuclear fuel has been only investigated for few types of reactors such as a high, temperature
    gas reactor (HTGR), fast breeder reactor, light water reactor (LWR) and heavy water reactor
    (HWR). For research reactors specifically, there are limited academic publications related to the
    la,test u.se of thorium. Hence, the main, interest, of this work is to compile and review the latest
    academic publications related to the active use of thorium, for research reactors in particular. The
    reviewed studies have been, divided into two categories which are experimented and simulation projects.
    The experimental projects are a,bold the ongoing thorium fuel tests that have been carried out. in an
    actual, research reactor. On the hand, the simulation work: is related to the computational analysis
    performed in predicting the neutronic behaviour of thorium based fuel in research reactors. The
    experimented study of thorium is currently active for the KAMINI research reactor. Additionally, most,
    simulation works focus on finding criticality and neutron spectra.
    Matched MeSH terms: Hot Temperature
  8. Abdul Rahman MB, Karjiban RA, Salleh AB, Jacobs D, Basri M, Thean Chor AL, et al.
    Protein Pept Lett, 2009;16(11):1360-70.
    PMID: 20001926
    The stability of biocatalysts is an important criterion for a sustainable industrial operation economically. T1 lipase is a thermoalkalophilic enzyme derived from Geobacillus zalihae strain T1 (T1 lipase) that was isolated from palm oil mill effluent (POME) in Malaysia. We report here the results of high temperatures molecular dynamics (MD) simulations of T1 lipase in explicit solvent. We found that the N-terminal moiety of this enzyme was accompanied by a large flexibility and dynamics during temperature-induced unfolding simulations which preceded and followed by clear structural changes in two specific regions; the small domain (consisting of helices alpha3 and alpha5, strands beta1 and beta2, and connecting loops) and the main catalytic domain or core domain (consisting of helices alpha6- alpha9 and connecting loops which located above the active site) of the enzyme. The results suggest that the small domain of model enzyme is a critical region to the thermostability of this organism.
    Matched MeSH terms: Hot Temperature
  9. Abdul Wahab R, Basri M, Raja Abdul Rahman RN, Salleh AB, Abdul Rahman MB, Leow TC
    Enzyme Microb Technol, 2016 Nov;93-94:174-181.
    PMID: 27702478 DOI: 10.1016/j.enzmictec.2016.08.020
    Site-directed mutagenesis of the oxyanion-containing amino acid Q114 in the recombinant thermophilic T1 lipase previously isolated from Geobacillus zalihae was performed to elucidate its role in the enzyme's enantioselectivity and reactivity. Substitution of Q114 with a hydrophobic methionine to yield mutant Q114M increased enantioselectivity (3.2-fold) and marginally improved reactivity (1.4-fold) of the lipase in catalysing esterification of ibuprofen with oleyl alcohol. The improved catalytic efficiency of Q114L was concomitant with reduced flexibility in the active site while the decreased enantioselectivity of Q114L could be directly attributed to diminished electrostatic repulsion of the substrate carboxylate ion that rendered partial loss in steric hindrance and thus enantioselectivity. The highest E-values for both Q114L (E-value 14.6) and Q114M (E-value 48.5) mutant lipases were attained at 50°C, after 12-16h, with a molar ratio of oleyl alcohol to ibuprofen of 1.5:1 and at 2.0% (w/v) enzyme load without addition of molecular sieves. Pertinently, site-directed mutagenesis on the Q114 oxyanion of T1 resulted in improved enantioselectivity and such approach may be applicable to other lipases of the same family. We demonstrated that electrostatic repulsion phenomena could affect flexibility/rigidity of the enzyme-substrate complex, aspects vital for enzyme activity and enantioselectivity of T1.
    Matched MeSH terms: Hot Temperature
  10. Abdulkarim, S.M., Ghazali, H.M.
    MyJurnal
    HyperDSC™(fast scan rate) was used to study the melting behavior of canola (CLO), sunflower (SFO), palm olein (PO), rice bran oils (RBO), and cocoa butter (CB), and was compared to the melting behaviors using conventional DSC. There was an increase in sensitivity with increase in scan rate. Slow scan rate (5 to 20C/min) gave low sensitivity, which increased when the scan rates were increased to 50, 100 and 200C/min. Peak resolution was affected by scan rate depending on the sample weight. Increase in the size of sample coupled with the use of fast scan rate decreased the peak resolution. Generally small sample sizes gave better peak resolution. Results of the effect of scan rate on glass transition (Tg) shows that Tg, which is a weak transition especially in crystalline and low amorphous materials was not detected using conventional scan rates (5 to 20oC/min). It was however detected using of hyperDSC™ scan rates (100 to 200oC/min). Increasing the scan rate resulted in an increase in the peak temperature and the elimination of shoulder peaks, which were caused due to the polymorphic behavior of the triacylglycerols in the oils. The increase in peak temperature caused a shift in the peak position towards a higher temperature value. There is a positive correlation between the peak temperature and scan rate. The correlation coefficients (r) for CLO, SFO, PO, RBO and CB were 0.96, 0.95, 0.97, 0.96 and 0.96 respectively.
    Matched MeSH terms: Hot Temperature
  11. Abdullah AZ, Ling PY
    J Hazard Mater, 2010 Jan 15;173(1-3):159-67.
    PMID: 19740600 DOI: 10.1016/j.jhazmat.2009.08.060
    The ambient sonocatalytic degradation of congo red, methyl orange, and methylene blue by titanium dioxide (TiO(2)) catalyst at initial concentrations between 10 and 50mg/L, catalyst loadings between 1.0 and 3.0mg/L and hydrogen peroxide (H(2)O(2)) concentrations up to 600 mg/L is reported. A 20 kHz ultrasonic processor at 50 W was used to accelerate the reaction. The catalysts were exposed to heat treatments between 400 and 1000 degrees C for up to 4h to induce phase change. Sonocatalysts with small amount of rutile phase showed better sonocatalytic activity but excessive rutile phase should be avoided. TiO(2) heated to 800 degrees C for 2h showed the highest sonocatalytic activity and the degradation of dyes was influenced by their chemical structures, chemical phases and characteristics of the catalysts. Congo red exhibited the highest degradation rate, attributed to multiple labile azo bonds to cause highest reactivity with the free radicals generated. An initial concentration of 10mg/L, 1.5 g/L of catalyst loading and 450 ppm of H(2)O(2) gave the best congo red removal efficiency of above 80% in 180 min. Rate coefficients for the sonocatalytic process was successfully established and the reused catalyst showed an activity drop by merely 10%.
    Matched MeSH terms: Hot Temperature
  12. Abdullah MM, Jamaludin L, Hussin K, Bnhussain M, Ghazali CM, Ahmad MI
    Int J Mol Sci, 2012;13(4):4388-95.
    PMID: 22605984 DOI: 10.3390/ijms13044388
    This paper presents the results of a study on the effect of temperature on geopolymers manufactured using pozzolanic materials (fly ash). In this paper, we report on our investigation of the performance of porous geopolymers made with fly ash after exposure to temperatures from 600 °C up to 1000 °C. The research methodology consisted of pozzolanic materials (fly ash) synthesized with a mixture of sodium hydroxide and sodium silicate solution as an alkaline activator. Foaming agent solution was added to geopolymer paste. The geopolymer paste samples were cured at 60 °C for one day and the geopolymers samples were sintered from 600 °C to 1000 °C to evaluate strength loss due to thermal damage. We also studied their phase formation and microstructure. The heated geopolymers samples were tested by compressive strength after three days. The results showed that the porous geopolymers exhibited strength increases after temperature exposure.
    Matched MeSH terms: Hot Temperature*
  13. Abdullah N, Chin NL, Yusof YA, Talib RA
    J Food Sci Technol, 2018 Mar;55(3):1207-1213.
    PMID: 29487464 DOI: 10.1007/s13197-017-3024-7
    The steady-state flow test was conducted on pink-fleshed guava, pink-fleshed pomelo and soursop juice concentrates using a rheometer to understand its rheological behaviour. The power law model was used and a master-curve was created using the shear rate-temperature-concentration superposition technique to predict rheological properties from a wide range of temperatures and concentrations. All three juice concentrates undergo a double horizontal shift whilst the pink-fleshed guava required an additional vertical shift. The final equations show shear-thinning behaviour of pink-fleshed guava, pink-fleshed pomelo and soursop with flow behaviour index of 0.2217, 0.7507 and 0.6347, respectively. The final master-curve predicts shear stress at wide range of shear rates, i.e. between 10-2 and 106 s-1 for the pink-fleshed guava, 100 and 106 s-1 for the pink-fleshed pomelo and 100 and 107 s-1 for the soursop. The results provide useful information and effective technique to predict fruit juice concentrates behaviour affected by heat changes during processing.
    Matched MeSH terms: Hot Temperature
  14. Abedi Karjiban R, Abdul Rahman MB, Basri M, Salleh AB, Jacobs D, Abdul Wahab H
    Protein J, 2009 Jan;28(1):14-23.
    PMID: 19130194 DOI: 10.1007/s10930-008-9159-7
    Molecular Dynamics (MD) simulations have been used to understand how protein structure, dynamics, and flexibility are affected by adaptation to high temperature for several years. We report here the results of the high temperature MD simulations of Bacillus stearothermophilus L1 (L1 lipase). We found that the N-terminal moiety of the enzyme showed a high flexibility and dynamics during high temperature simulations which preceded and followed by clear structural changes in two specific regions; the small domain and the main catalytic domain or core domain of the enzyme. These two domains interact with each other through a Zn(2+)-binding coordination with Asp-61 and Asp-238 from the core domain and His-81 and His-87 from the small domain. Interestingly, the His-81 and His-87 were among the highly fluctuated and mobile residues at high temperatures. The results appear to suggest that tight interactions of Zn(2+)-binding coordination with specified residues became weak at high temperature which suggests the contribution of this region to the thermostability of the enzyme.
    Matched MeSH terms: Hot Temperature
  15. Abedi Karjiban R, Lim WZ, Basri M, Abdul Rahman MB
    Protein J, 2014 Aug;33(4):369-76.
    PMID: 24871480 DOI: 10.1007/s10930-014-9568-8
    Lipases are known for their versatility in addition to their ability to digest fat. They can be used for the formulation of detergents, as food ingredients and as biocatalysts in many industrial processes. Because conventional enzymes are frangible at high temperatures, the replacement of conventional chemical routes with biochemical processes that utilize thermostable lipases is vital in the industrial setting. Recent theoretical studies on enzymes have provided numerous fundamental insights into the structures, folding mechanisms and stabilities of these proteins. The studies corroborate the experimental results and provide additional information regarding the structures that were determined experimentally. In this paper, we review the computational studies that have described how temperature affects the structure and dynamics of thermoenzymes, including the thermoalkalophilic L1 lipase derived from Bacillus stearothermophilus. We will also discuss the potential of using pressure for the analysis of the stability of thermoenzymes because high pressure is also important for the processing and preservation of foods.
    Matched MeSH terms: Hot Temperature*
  16. Abusham RA, Rahman RN, Salleh AB, Basri M
    Microb Cell Fact, 2009 Apr 09;8:20.
    PMID: 19356254 DOI: 10.1186/1475-2859-8-20
    BACKGROUND: Many researchers have reported on the optimization of protease production; nevertheless, only a few have reported on the optimization of the production of organic solvent-tolerant proteases. Ironically, none has reported on thermostable organic solvent-tolerant protease to date. The aim of this study was to isolate the thermostable organic solvent-tolerant protease and identify the culture conditions which support its production. The bacteria of genus Bacillus are active producers of extra-cellular proteases, and the thermostability of enzyme production by Bacillus species has been well-studied by a number of researchers. In the present study, the Bacillus subtilis strain Rand was isolated from the contaminated soil found in Port Dickson, Malaysia.

    RESULTS: A thermostable organic solvent-tolerant protease producer had been identified as Bacillus subtilis strain Rand, based on the 16S rRNA analysis conducted, as well as the morphological characteristics and biochemical properties. The production of the thermostable organic solvent-tolerant protease was optimized by varying various physical culture conditions. Inoculation with 5.0% (v/v) of (AB600 = 0.5) inoculum size, in a culture medium (pH 7.0) and incubated for 24 h at 37 degrees C with 200 rpm shaking, was the best culture condition which resulted in the maximum growth and production of protease (444.7 U/ml; 4042.4 U/mg). The Rand protease was not only stable in the presence of organic solvents, but it also exhibited a higher activity than in the absence of organic solvent, except for pyridine which inhibited the protease activity. The enzyme retained 100, 99 and 80% of its initial activity, after the heat treatment for 30 min at 50, 55, and 60 degrees C, respectively.

    CONCLUSION: Strain Rand has been found to be able to secrete extra-cellular thermostable organic solvent-tolerant protease into the culture medium. The protease exhibited a remarkable stability towards temperature and organic solvent. This unique property makes it attractive and useful to be used in industrial applications.

    Matched MeSH terms: Hot Temperature
  17. Adam SK, Das S, Jaarin K
    Int J Exp Pathol, 2009 Jun;90(3):321-7.
    PMID: 19563614 DOI: 10.1111/j.1365-2613.2009.00658.x
    Hypercholesterolaemia, increase in lipid peroxidation and hyperhomocysteinaemia may contribute to the pathogenesis of atherosclerosis. This study was performed to examine the effects of repeatedly heated palm oil mixed with 2% cholesterol diet on atherosclerosis in oestrogen-deficient postmenopausal rats. Ovariectomy causes disruption of tunica intima layer of the rat aorta simulating a postmenopausal condition in females. Twenty-four ovariectomized female Sprague-Dawley rats were divided into four groups. The control group received 2% cholesterol diet without palm oil. A diet with 2% cholesterol content fortified with fresh, once-heated and five-times-heated palm oil was given to the other treatment groups. The rats were sacrificed at the end of 4 months of study and the aortic arch tissue was processed for histomorphometry and electron microscopy. On observation, there was disruption of the intimal layer of the ovariectomized rat aorta. There was no obvious ultrastructural change in the aorta of the rats fed with fresh palm oil. The ultrastructural changes were minimal with once-heated palm oil, in which there was a focal disruption of the endothelial layer. The focal disruption was more pronounced with five-times-heated palm oil. The results of this study show that the ingestion of fresh palm oil may have a protective effect on the aorta but such a protective action may be lost when the palm oil is repeatedly heated. The study may be clinically important for all postmenopausal women who are susceptible to atherosclerosis.
    Matched MeSH terms: Hot Temperature
  18. Adam SK, Das S, Othman F, Jaarin K
    Clinics (Sao Paulo), 2009;64(11):1113-9.
    PMID: 19936186 DOI: 10.1590/S1807-59322009001100012
    To observe the effects of consuming repeatedly heated soy oil on the aortic tissues of estrogen-deficient rats.
    Matched MeSH terms: Hot Temperature
  19. Agamuthu P, Faizura PN
    Waste Manag Res, 2005 Apr;23(2):95-100.
    PMID: 15864950
    Plastic waste constitutes the third largest waste volume in Malaysian municipal solid waste (MSW), next to putrescible waste and paper. The plastic component in MSW from Kuala Lumpur averages 24% (by weight), whereas the national mean is about 15%. The 144 waste dumps in the country receive about 95% of the MSW, including plastic waste. The useful life of the landfills is fast diminishing as the plastic waste stays un-degraded for more than 50 years. In this study the compostability of polyethylene and pro-oxidant additive-based environmentally degradable plastics (EDP) was investigated. Linear low-density polyethylene (LLDPE) samples exposed hydrolytically or oxidatively at 60 degrees C showed that the abiotic degradation path was oxidative rather than hydrolytic. There was a weight loss of 8% and the plastic has been oxidized as shown by the additional carbonyl group exhibited in the Fourier transform infra red (FTIR) Spectrum. Oxidation rate seemed to be influenced by the amount of pro-oxidant additive, the chemical structure and morphology of the plastic samples, and the surface area. Composting studies during a 45-day experiment showed that the percentage elongation (reduction) was 20% for McD samples [high-density polyethylene, (HDPE) with 3% additive] and LL samples (LLDPE with 7% additive) and 18% reduction for totally degradable plastic (TDP) samples (HDPE with 3% additive). Lastly, microbial experiments using Pseudomonas aeroginosa on carbon-free media with degradable plastic samples as the sole carbon source, showed confirmatory results. A positive bacterial growth and a weight loss of 2.2% for degraded polyethylene samples were evident to show that the degradable plastic is biodegradable.
    Matched MeSH terms: Hot Temperature
  20. Aghamohammadi N, Fong CS, Idrus MHM, Ramakreshnan L, Sulaiman NM
    Sci Total Environ, 2021 Aug 15;782:146611.
    PMID: 33838362 DOI: 10.1016/j.scitotenv.2021.146611
    Due to the changing climate, more frequent and prolonged heatwaves are expected to have a catastrophic consequence on urban human settlement. In tropical cities such as Kuala Lumpur (KL), the quality of the urban environment is made worse by urban heat island (UHI) phenomena due to poor urban planning practices. The prolonged exposure to urban heat is hypothesized to influence human health and well-being, especially in tropical urban areas with high population density. Therefore, a study was conducted to understand the association of urban heat stress with physical, psychosomatic and psychological (PPP) health symptoms within a tropical urban setting. Continuous urban microclimate monitoring is conducted using an automated weather station to define the level of heat stress in the study area expressed as Physiological Equivalent Temperature (PET). A cross-sectional approach is used to identify heat-related health symptoms experienced by the urban population. Through exploratory factor analysis, a total of 38 PPP health symptoms are reduced into 8 heat-related health clusters which are sensory organ pain, heat-related illnesses, cardiopulmonary, pain, fatigue, anxiety, somatization, and depression-related symptoms. Heat stress was found to significantly affect psychosomatic pain (p = 0.016) as well as psychological anxiety (p = 0.022) and somatization (p = 0.041) related symptoms. Other health clusters were not significantly associated with heat stress. More studies are needed to unravel the influence of confounding factors and the long-term impact of urban heat on the health and well-being of the urban population in a tropical city.
    Matched MeSH terms: Hot Temperature*
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