Displaying publications 1 - 20 of 120 in total

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  1. Tropical stormwater nutrient degradation using nano-TiO2 in photocatalytic reactor detention pond
    Rad S, Shamsudin S, Taha MR, Shahid S
    Water Sci Technol, 2016;73(2):405-13.
    PMID: 26819397 DOI: 10.2166/wst.2015.465
    The photo-degradation of nutrients in stormwater in photocatalytic reactor wet detention pond using nano titanium dioxide (TiO2) in concrete was investigated in a scale model as a new stormwater treatment method. Degradation of phosphate and nitrate in the presence of nano-TiO2 under natural ultra violet (UV) from tropical sunlight was monitored for 3 weeks compared with normal ponds. Two types of cement, including ordinary Portland and white cement mixed with TiO2 nano powder, were used as a thin cover to surround the body of the pond. Experiments with and without the catalyst were carried out for comparison and control. Average Anatase diameter of 25 nm and Rutile 100 nm nano particles were applied at three different mixtures of 3, 10 and 30% weight. The amounts of algae available orthophosphate and nitrate, which cause eutrophication in the ponds, were measured during the tests. Results revealed that the utilization of 3% up to 30% weight nano-TiO2 can improve stormwater outflow quality by up to 25% after 48 h and 57% after 3 weeks compared with the control sample in normal conditions with average nutrient (phosphate and nitrate) removal of 4% after 48 h and 10% after 3 weeks.
    Matched MeSH terms: Sunlight
  2. A new achievement in green degradation of aqueous organic pollutants under visible-light irradiation
    Abdollahi Y, Sabbaghi S, Abouzari-Lotf E, Jahangirian H, Sairi NA
    Water Sci Technol, 2018 Mar;77(5-6):1493-1504.
    PMID: 29595152 DOI: 10.2166/wst.2018.017
    The global attention has been focused on degradation of the environmental organic pollutants through green methods such as advanced oxidation processes (AOPs) under sunlight. However, AOPs have not yet been efficient in function of the photocatalyst that has been used. In this work, firstly, CaCu3Ti4O12 nanocomposite was simultaneously synthesized and decorated in different amounts of graphene oxide to enhance photodegradation of the organics. The result of the photocatalyst characterization showed that the sample with 8% graphene presented optimum photo-electrical properties such as low band gap energy and a great surface area. Secondly, the photocatalyst was applied for photodegradation of an organic model in a batch photoreactor. Thirdly, to scale up the process and optimize the efficiency, the photodegradation was modeled by multivariate semi-empirical methods. As the optimized condition showed, 45 mg/L of the methyl-orange has been removed at pH 5.8 by 0.96 g/L of the photocatalyst during 288 min of the light irradiation. Moreover, the photodegradation has been scaled up for industrial applications by determining the importance of the input effective variables according to the following organics order > photocatalyst > pH > irradiation time.
    Matched MeSH terms: Sunlight*
  3. Fulltext Influencing factors for household water quality improvement in reducing diarrhoea in resource-limited areas
    Zin T, Mudin KD, Myint T, Naing DKS, Sein T, Shamsul BS
    WHO South East Asia J Public Health, 2013 Jan-Mar;2(1):6-11.
    PMID: 28612817 DOI: 10.4103/2224-3151.115828
    BACKGROUND AND OBJECTIVES: Water and sanitation are major public health issues exacerbated by rapid population growth, limited resources, disasters and environmental depletion. This study was undertaken to study the influencing factors for household water quality improvement for reducing diarrhoea in resource-limited areas.

    MATERIALS AND METHODS: Data were collected from articles and reviews from relevant randomized controlled trials, new articles, systematic reviews and meta-analyses from PubMed, World Health Organization (WHO), United Nations Children's Fund (UNICEF) and WELL Resource Centre For Water, Sanitation And Environmental Health.

    DISCUSSION: Water quality on diarrhoea prevention could be affected by contamination during storage, collection and even at point-of-use. Point-of-use water treatment (household-based) is the most cost-effective method for prevention of diarrhoea. Chemical disinfection, filtration, thermal disinfection, solar disinfection and flocculation and disinfection are five most promising household water treatment methodologies for resource-limited areas.

    CONCLUSION: Promoting household water treatment is most essential for preventing diarrhoeal disease. In addition, the water should be of acceptable taste, appropriate for emergency and non-emergency use.
    Matched MeSH terms: Sunlight
  4. Fulltext SOLAR PHOTOCATALYTIC EFFICIENCY OF ZINC OXIDE FOR WATER DECONTAMINATION
    FARAH EILYANA MOHAMED
    UMT Journal of Undergraduate Research, 2019;1(1):92-102.
    MyJurnal
    Solar photocatalysis is a green technology that takes advantage of sustainable solar energy for enhancing oxidation process of numerous harmful water contaminants. In this study, a custom solar driven zinc oxide (ZnO)-mediated photocatalytic system was developed and its efficiency to remove organic contaminants as well as to disinfect selected bacteria was investigated. Methylene blue (MB) dye was used as the model organic contaminant, while Escherichia coli(E.coli) was used as the model fecal coliform bacteria in contaminated water. A series of photodegradation experiments were conducted on water contaminated with either 10 mg/L of MB or ~1010CFU/ml of E.coli. The experiments were completed under sunlight irradiation in the presence of 1 g/L of nano ZnO photocatalyst for up to 6 hours. Using a solar thermal collector, the photoreactor operated in the temperature range of 25 to 50 oC. The findings revealed that the combination of solar thermal with solar photocatalysis usingZnO intensified the degradation of MB and disinfection of E.coli. 98.08% of MB dye and 99.99% of E.coliwere successfully removed from the water within the first 3 hours of treatment. Almost complete removal was eventually achieved after 6 hours of treatment. It is therefore suggested that ZnO-based solar photocatalytic system developed in this study is highly efficient at enhancing water decontamination process.
    Matched MeSH terms: Sunlight
  5. Fulltext Ecological Characteristics of a Gonystylus bancanus-rich Area in Pekan Forest Reserve, Pahang, Malaysia
    Hamzah KA, Ismail P, Kassim AR, Hassan CH, Akeng G, Said NM
    Trop Life Sci Res, 2009 Dec;20(2):15-27.
    PMID: 24575176 MyJurnal
    Tropical peat swamp forest (PSF) is a unique wetland ecosystem with distinct vegetation types. Due to the waterlogged environment, the stand characteristics in this ecosystem are different from those of other inland forests. This paper highlights stand characteristics of a PSF based on our investigation of a 1 ha ecological plot established in a Virgin Jungle Reserve (VJR) at Compartment 100, Pekan Forest Reserve, Pahang, Malaysia. This site is considered a Gonystylus bancanus-rich area. From the inventory, we recorded a total of 49 tree species from 38 genera and 25 families among all trees of ≥ 10 cm in diameter at breast height. Calophyllum ferrugineum var. ferrugineum was the most abundant species, followed by G. bancanus. The forest appeared healthy, as all tree characteristics (crown shape, log grade and climber infestation) generally fell within Classes 1 and 2 (good and moderate categories), with the exception of crown illumination which majority of the trees were rated as class 3 (received less sunlight). The latter finding indicates that most of the trees living under the canopy received minimal illumination. In terms of total tree biomass, we estimated that about 414.6 tonnes exist in this 1 ha area; this tree biomass is higher than in some PSF areas of Sumatra, Indonesia.
    Matched MeSH terms: Sunlight
  6. Fulltext Toxicity of Chlorophyllin against Lymnaea acuminata at Different Wavelengths of Visible Light
    Chaturvedi D, Singh VK
    Trop Life Sci Res, 2016 Aug;27(2):25-36.
    PMID: 27688849 DOI: 10.21315/tlsr2016.27.2.3
    Fasciolosis is a water and food-borne disease caused by the liver fluke Fasciola hepatica and Fasciola gigantica. This disease is widespread in different parts of the world. Lymnaeidae and Planorbidae snails are the intermediate hosts of these flukes. Snail population management is a good tool to control fasciolosis because gastropods represent the weakest link in the life-cycle of trematodes. Chlorophyll can be extracted from any green plant. Chlorophyllin was prepared from spinach in 100% ethanol by using different types of chemicals. The chlorophyll obtained from spinach was transformed into water-soluble chlorophyllin. In the present paper, toxicity of chlorophyllin against the snail Lymnaea acuminata was time and concentration dependent. The toxicity of extracted and pure chlorophyllin at continuous 4 h exposure of sunlight was highest with lethal concentration (LC50) of 331.01 mg/L and 2.60 mg/L, respectively, than discontinuous exposure of sunlight up to 8 h with LC50 of 357.04 mg/L and 4.94 mg/L, respectively. Toxicity of extracted chlorophyllin was noted in the presence of different monochromatic visible lights. The highest toxicity was noted in yellow light (96 h, LC50 392.77 mg/L) and the lowest in green light (96 h, LC50 833.02 mg/L). Chlorophyllin in combination with solar radiation or different wavelength of monochromatic visible lights may become a latent remedy against the snail L. acuminata. It was demonstrated that chlorophyllin was more toxic in sunlight. Chlorophyllin is ecologically safe and more economical than synthetic molluscicides which have the potential to control the incidence of fasciolosis in developing countries.
    Matched MeSH terms: Sunlight
  7. Fulltext Laboratory bioefficacy of nine commercial formulations of temephos against larvae of Aedes aegypti (L.), Aedes albopictus Skuse and Culex quinquefasciatus Say
    Chen CD, Lee HL, Chan CK, Ang CL, Azahari AH, Lau KW, et al.
    Trop Biomed, 2009 Dec;26(3):360-5.
    PMID: 20237452
    The bioefficacy of nine commercial formulations of temephos against Aedes aegypti, Aedes albopictus and Culex quinquefasciatus larvae were evaluated in the laboratory. WHO larval bioassay with operational dosage of temephos at 1 mg/L was performed. The larval mortality was recorded every 5 minutes until complete mortality was achieved. All formulations of temephos exhibited various toxicity level against Ae. aegypti, Ae. albopictus and Cx. quinquefasciatus. Generally, larvae of Cx. quinquefasciatus was susceptible to all formulations of temephos, followed by Ae. aegypti and Ae. albopictus.
    Matched MeSH terms: Sunlight
  8. Fulltext Competitive interaction of Axonopus compressus and Asystasia gangetica under contrasting sunlight intensity
    Samedani B, Juraimi AS, Anwar MP, Rafii MY, Sheikh Awadz SH, Anuar AR
    ScientificWorldJournal, 2013;2013:308646.
    PMID: 24163618 DOI: 10.1155/2013/308646
    Axonopus compressus is one of the native soft grass species in oil palm in Malaysia which can be used as a cover crop. The competitive ability of A. compressus to overcome A. gangetica was studied using multiple-density, multiple-proportion replacements series under a glasshouse and full sunlight conditions in a poly bag for 10 weeks. A. compressus produced more dry weight and leaf area when competing against A. gangetica than in monoculture at both densities in the full sunlight and at high density in the shade. Moreover, the relative yield and relative crowding coefficients also indicated A. compressus is a stronger competitor than A. gangetica at both densities in the full sunlight and high density in the shade. It seemed that A. gangetica plants in the shade did not compete with each other and were more competitive against A. compressus as could influence A. compressus height in the shade. It is concluded that although suppression of A. gangetica by A. compressus occurred under full sunlight, irrespective of plant density, this ability reduced under shade as A. compressus density decreased. The result suggests that A. compressus in high density could be considered as a candidate for cover crops under oil palm canopy.
    Matched MeSH terms: Sunlight*
  9. The sunshine-mediated trigger of synchronous flowering in the tropics: the rubber tree as a study model
    Yeang HY
    New Phytol, 2007;176(4):730-5.
    PMID: 17997756
    Matched MeSH terms: Sunlight*
  10. Vitamin D deficiency: A single centre analysis of patients from 136 countries
    Haq A, Svobodová J, Imran S, Stanford C, Razzaque MS
    J Steroid Biochem Mol Biol, 2016 11;164:209-213.
    PMID: 26877203 DOI: 10.1016/j.jsbmb.2016.02.007
    Vitamin D deficiency is a global problem, thought to be related to lack of sunlight exposure, and usually accompanied by reduced dietary intake. This study was designed to determine vitamin D status of 60,979 patients admitted to the Burjeel Hospital of VPS healthcare in Abu Dhabi, United Arab Emirates (UAE) from October 2012 to September 2014. The total concentrations of vitamin D [25(OH)D] of all the studied patients were measured in a single laboratory. Of the studied patients, 57.5% were female and 42.5% were male. Serum 25(OH)D (total) measurements showed 82.5% of the studied patients have vitamin D deficiency to insufficiency. 26.4% of females and 18.4% of males have extreme deficiency of 25(OH)D. There was higher variability of vitamin D in group of females then males according to coefficient of variation. In our studied cohort teenagers (13-19 years) have shown the lowest levels of serum vitamin D (data not shown and will be communicated as a separate publication). The prevalence of hypovitaminosis D is significantly high among population of UAE, Saudi Arabia and many Middle Eastern countries, especially among women, despite abundant sunshine. 86.1% UAE nationals and 78.9% visitors of other nationalities were found <75nmol/L of 25(OH)D. 28.4% of UAE nationals and 17.5% of visitors of other nationalities have extreme deficiency of 25(OH)D. Our results are significant, as all of our patients are residing permanently in the UAE or visitors that has yearlong sunlight. In addition, measuring 25(OH)D concentrations in a single laboratory minimized test level variations. Our current study formed the basis of further studies to determine if vitamin D deficiency and insufficiency can aggravate systemic diseases, including hypertension, diabetes or obesity that are also wide-spread in the Middle Eastern region.
    Matched MeSH terms: Sunlight
  11. Fulltext Pharmacologically antagonizing the CXCR4-CXCL12 chemokine pathway with AMD3100 inhibits sunlight-induced skin cancer
    Sarchio SNE, Scolyer RA, Beaugie C, McDonald D, Marsh-Wakefield F, Halliday GM, et al.
    J Invest Dermatol, 2014 Apr;134(4):1091-1100.
    PMID: 24226205 DOI: 10.1038/jid.2013.424
    One way sunlight causes skin cancer is by suppressing anti-tumor immunity. A major mechanism involves altering mast cell migration via the C-X-C motif chemokine receptor 4-C-X-C motif chemokine ligand 12 (CXCR4-CXCL12) chemokine pathway. We have discovered that pharmacologically blocking this pathway with the CXCR4 antagonist AMD3100 prevents both UV radiation-induced immune suppression and skin cancer. The majority of control mice receiving UV-only developed histopathologically confirmed squamous cell carcinomas. In contrast, skin tumor incidence and burden was significantly lower in AMD3100-treated mice. Perhaps most striking was that AMD3100 completely prevented the outgrowth of latent tumors that occurred once UV irradiation ceased. AMD3100 protection from UV immunosuppression and skin cancer was associated with reduced mast cell infiltration into the skin, draining lymph nodes, and the tumor itself. Thus a major target of CXCR4 antagonism was the mast cell. Our results indicate that interfering with UV-induced CXCL12 by antagonizing CXCR4 significantly inhibits skin tumor development by blocking UV-induced effects on mast cells. Hence, the CXCR4-CXCL12 chemokine pathway is a novel therapeutic target in the prevention of UV-induced skin cancer.
    Matched MeSH terms: Sunlight*
  12. Milk vitamin D in relation to the 'adequate intake' for 0-6-month-old infants: a study in lactating women with different cultural backgrounds, living at different latitudes
    Stoutjesdijk E, Schaafsma A, Nhien NV, Khor GL, Kema IP, Hollis BW, et al.
    Br J Nutr, 2017 Nov;118(10):804-812.
    PMID: 29103383 DOI: 10.1017/S000711451700277X
    Breast-fed infants are susceptible to vitamin D deficiency rickets. The current vitamin D 'adequate intake' (AI) for 0-6-month-old infants is 10 µg/d, corresponding with a human milk antirachitic activity (ARA) of 513 IU/l. We were particularly interested to see whether milk ARA of mothers with lifetime abundant sunlight exposure reaches the AI. We measured milk ARA of lactating mothers with different cultural backgrounds, living at different latitudes. Mature milk was derived from 181 lactating women in the Netherlands, Curaçao, Vietnam, Malaysia and Tanzania. Milk ARA and plasma 25-hydroxyvitamin D (25(OH)D) were analysed by liquid-chromatography-MS/MS; milk fatty acids were analysed by GC-flame ionisation detector (FID). None of the mothers reached the milk vitamin D AI. Milk ARA (n; median; range) were as follows: Netherlands (n 9; 46 IU/l; 3-51), Curaçao (n 10; 31 IU/l; 5-113), Vietnam: Halong Bay (n 20; 58 IU/l; 23-110), Phu Tho (n 22; 28 IU/l; 1-62), Tien Giang (n 20; 63 IU/l; 26-247), Ho-Chi-Minh-City (n 18; 49 IU/l; 24-116), Hanoi (n 21; 37 IU/l; 11-118), Malaysia-Kuala Lumpur (n 20; 14 IU/l; 1-46) and Tanzania-Ukerewe (n 21; 77 IU/l; 12-232) and Maasai (n 20; 88 IU/l; 43-189). We collected blood samples of these lactating women in Curaçao, Vietnam and from Tanzania-Ukerewe, and found that 33·3 % had plasma 25(OH)D levels between 80 and 249·9 nmol/l, 47·3 % between 50 and 79·9 nmol/l and 19·4 % between 25 and 49·9 nmol/l. Milk ARA correlated positively with maternal plasma 25(OH)D (range 27-132 nmol/l, r 0·40) and milk EPA+DHA (0·1-3·1 g%, r 0·20), and negatively with latitude (2°S-53°N, r -0·21). Milk ARA of mothers with lifetime abundant sunlight exposure is not even close to the vitamin D AI for 0-6-month-old infants. Our data may point at the importance of adequate fetal vitamin D stores.
    Matched MeSH terms: Sunlight*
  13. Facile synthesis of graphene oxide-silver nanocomposite and its modified electrode for enhanced electrochemical detection of nitrite ions
    Ikhsan NI, Rameshkumar P, Pandikumar A, Mehmood Shahid M, Huang NM, Vijay Kumar S, et al.
    Talanta, 2015 Nov 1;144:908-14.
    PMID: 26452907 DOI: 10.1016/j.talanta.2015.07.050
    In this report, silver nanoparticles (Ag NPs) were successfully deposited on graphene oxide (GO) sheets to form GO-Ag nanocomposite using garlic extract and sunlight and the nanocomposite modified glassy carbon (GC) electrode was applied as an electrochemical sensor for the detection of nitrite ions. The formation of GO-Ag nanocomposite was confirmed by using UV-visible absorption spectroscopy, TEM, XRD and FTIR spectroscopy analyses. Further, TEM pictures showed a uniform distribution Ag on GO sheets with an average size of 19 nm. The nanocomposite modified electrode produced synergistic catalytic current in nitrite oxidation with a negative shift in overpotential. The limit of detection (LOD) values were found as 2.1 µM and 37 nM, respectively using linear sweep voltammetry (LSV) and amperometric i-t curve techniques. The proposed sensor was stable, reproducible, sensitive and selective toward the detection nitrite and could be applied for the detection of nitrite in real water sample.
    Matched MeSH terms: Sunlight
  14. Vitamin D deficiency and insufficiency in Malaysian children with spina bifida
    Fong CY, Ong FN, Ong LC, Khoo TB, Lee ML
    Spinal Cord, 2020 Sep;58(9):1030-1036.
    PMID: 32060410 DOI: 10.1038/s41393-020-0441-7
    STUDY DESIGN: Cross-sectional study.

    OBJECTIVE: To determine the prevalence and potential risk factors of vitamin D deficiency and insufficiency among Malaysian children with spina bifida.

    SETTING: Four Malaysian tertiary hospitals.

    METHODS: Children with spina bifida were assessed for potential demographic, disease severity and lifestyle risk factors for vitamin D deficiency and insufficiency. Blood for 25-hydroxy vitamin D (25(OH)D) was taken. Vitamin D deficiency was defined as 25(OH)D levels ≤ 37.5 nmol/L and insufficiency as 37.6-50 nmol/L.

    RESULTS: Eighty children aged 2-18 years (42 males) participated in the study. Vitamin D levels ranged from 14 to 105 nmol/L (mean 52.8, SD 19.1). Vitamin D deficiency was identified in 18 (22.5%) and insufficiency in 26 (32.5%) children. Logistic regression analysis showed that skin exposure to sunlight ≤ 21% body surface area (OR: 6.2, CI 1.7-22.9) and duration of sun exposure ≤ 35 min/day (OR: 4.0, CI 1.2-14.1) were significant risk factors for vitamin D deficiency and insufficiency, respectively.

    CONCLUSIONS: Over half (55%) of Malaysian children with spina bifida seen in urban tertiary hospitals have vitamin D insufficiency and deficiency. Lifestyle sun exposure behaviours were risk factors for vitamin D deficiency and insufficiency.

    Matched MeSH terms: Sunlight*
  15. Fulltext Integration of an on-axis general sun-tracking formula in the algorithm of an open-loop sun-tracking system
    Chong KK, Wong CW, Siaw FL, Yew TK, Ng SS, Liang MS, et al.
    Sensors (Basel), 2009;9(10):7849-65.
    PMID: 22408483 DOI: 10.3390/s91007849
    A novel on-axis general sun-tracking formula has been integrated in the algorithm of an open-loop sun-tracking system in order to track the sun accurately and cost effectively. Sun-tracking errors due to installation defects of the 25 m(2) prototype solar concentrator have been analyzed from recorded solar images with the use of a CCD camera. With the recorded data, misaligned angles from ideal azimuth-elevation axes have been determined and corrected by a straightforward changing of the parameters' values in the general formula of the tracking algorithm to improve the tracking accuracy to 2.99 mrad, which falls below the encoder resolution limit of 4.13 mrad.
    Matched MeSH terms: Sunlight
  16. Fulltext Design and Implementation of Fuzzy Compensation Scheme for Temperature and Solar Irradiance Wireless Sensor Network (WSN) on Solar Photovoltaic (PV) System
    Pazikadin AR, Rifai D, Ali K, Mamat NH, Khamsah N
    Sensors (Basel), 2020 Nov 25;20(23).
    PMID: 33255797 DOI: 10.3390/s20236744
    Photovoltaic (PV) systems need measurements of incident solar irradiance and PV surface temperature for performance analysis and monitoring purposes. Ground-based network sensor measurement is preferred in many near real-time operations such as forecasting and photovoltaic (PV) performance evaluation on the ground. Hence, this study proposed a Fuzzy compensation scheme for temperature and solar irradiance wireless sensor network (WSN) measurement on stand-alone solar photovoltaic (PV) system to improve the sensor measurement. The WSN installation through an Internet of Things (IoT) platform for solar irradiance and PV surface temperature measurement was fabricated. The simulation for the solar irradiance Fuzzy Logic compensation (SIFLC) scheme and Temperature Fuzzy Logic compensation (TFLC) scheme was conducted using Matlab/Simulink. The simulation result identified that the scheme was used to compensate for the error temperature and solar irradiance sensor measurements over a variation temperature and solar irradiance range from 20 to 60 °C and from zero up to 2000 W/m2. The experimental results show that the Fuzzy Logic compensation scheme can reduce the sensor measurement error up to 17% and 20% for solar irradiance and PV temperature measurement.
    Matched MeSH terms: Sunlight
  17. Fulltext Boosting Photovoltaic Performance of Dye-Sensitized Solar Cells Using Silver Nanoparticle-Decorated N,S-Co-Doped-TiO2 Photoanode
    Lim SP, Pandikumar A, Lim HN, Ramaraj R, Huang NM
    Sci Rep, 2015;5:11922.
    PMID: 26146362 DOI: 10.1038/srep11922
    A silver nanoparticle-decorated N,S-co-doped TiO2 nanocomposite was successfully prepared and used as an efficient photoanode in high-performance dye-sensitized solar cells (DSSCs) with N719 dye. The DSSCs assembled with the N,S-TiO2@Ag-modified photoanode demonstrated an enhanced solar-to-electrical energy conversion efficiency of 8.22%, which was better than that of a DSSC photoanode composed of unmodified TiO2 (2.57%) under full sunlight illumination (100 mWcm(-2), AM 1.5 G). This enhanced efficiency was mainly attributed to the reduced band gap energy, improved interfacial charge transfer, and retarded charge recombination process. The influence of the Ag content on the overall efficiency was also investigated, and the optimum Ag content with N,S-TiO2 was found to be 20 wt%. Because of the enhanced solar energy conversion efficiency of the N,S-TiO2@Ag nanocomposite, it should be considered as a potential photoanode for high-performance DSSCs.
    Matched MeSH terms: Sunlight
  18. Fulltext Simple modification measurement of photodegradability of polymers by using photo-induced chemiluminescence technique
    Siti Farhana Zakaria, Millington, Keith R.
    Scientific Research Journal, 2013;10(2):0-0.
    MyJurnal
    Polymers and organic materials that are exposed to sunlight undergo photooxidation, which leads to deterioration of their physical properties. To allow adequate performance under outdoor conditions, synthetic polymers require additives such as antioxidants and UV absorbers. A major problem with optimising polymer formulations to maximise their working life span is that accelerated weathering tests are empirical. The conditions differ significantly from real weathering situations, and samples require lengthy irradiation period. Degradation may not be apparent in the early stages of exposure, although this is when products such as hydroperoxides are formed which later cause acceleration of oxidation. A simple way of quantifying the number of free radicals presents in organic materials following exposure to light or heat is by measuring chemiluminescence (CL) emission. Most polymers emit CL when they undergo oxidative degradation, and it originates from the bimolecular reaction of macroperoxy radicals which creates an excited carbonyl.
    Matched MeSH terms: Sunlight
  19. Energy, exergy and efficiency analysis of a flat plate solar collector used as air heater
    Maazullah Khan, Abdurab, Muhammad Hanif, Mansoor Khan Khattak, Muhammad Ramzan
    Sains Malaysiana, 2018;47:1061-1067.
    Air heating by solar collectors is renewable technology providing hot air for different purposes. The present research
    emphasizes on analysis of energy, exergy and efficiency of a flat plate solar air heater. The analysis model was tested
    on five different air mass flow rates of 0.5 (Natural), 1.31, 2.11, 2.72 and 3.03 kgs-1 under three different tilt angles of
    25, 35 (Recommended) and 50o
    . The data was replicated three times making a total of 45 treatments. A two factorial
    completely randomized design was used to find if there is any significant difference among the treatments. The results
    showed that the solar collector gave better performance at air mass flow of 3.03 kgs-1 under tilt of 35o
    . At maximum
    air mass flow rate of 3.03 kgs-1and optimum tilt angle of 35o
    the maximum energetic efficiency of 51%, while minimum
    exergetic efficiency of 24% and maximum overall efficiency of 71% were recorded. It was concluded that to get maximum
    thermal efficiencies of 71% from flat plate solar collector used as an air heater must be operated at high air mass flow
    rates of 3.03 kgs-1under 35o
    tilt angle at Peshawar, Pakistan.
    Matched MeSH terms: Sunlight
  20. Decolorization and Mineralization of Batik Wastewater through Solar Photocatalytic Process
    Wan Fadhilah Khalik, Ong SA, Wong YS, Nik Athirah Yusoff, Fahmi Ridwan, Ho LN
    Sains Malaysiana, 2015;44:607-612.
    In this study, the photocatalytic degradation of batik wastewater in the presence of zinc oxide (ZnO) as photocatalyst was
    investigated. The effect of various operating parameters, such as pH of batik wastewater, catalyst dosage and aeration
    on the photocatalytic degradation process, was examined. The mineralization of batik wastewater was also evaluated
    through chemical oxygen demand analysis. The decolorization of batik wastewater was enhanced at acidic conditions
    (pH3) which was 88.2% after 10 h irradiated under solar light, meanwhile its mineralization was 286 mg/L after 12 h
    irradiation time. The data obtained for photocatalytic degradation of batik wastewater was well fitted with the LangmuirHinshelwood
    kinetic model. It can be concluded that batik wastewater could be decolorized and mineralized under solar
    light irradiation with presence of ZnO.
    Matched MeSH terms: Sunlight
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