Displaying publications 1 - 20 of 450 in total

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  1. Sahid IB, Teoh SS
    Bull Environ Contam Toxicol, 1994 Feb;52(2):226-30.
    PMID: 8123982
    Matched MeSH terms: Water/chemistry
  2. Osman A, Zaleha MI, Letchumen R, Khalid BA
    Med J Malaysia, 1995 Sep;50(3):256-62.
    PMID: 8926905
    The study was conducted to compare the prevalence of goitre among Malays and Aborigines in remote inland rural areas to those in coastal areas. All subjects were examined thoroughly by an experienced endocrinologist for the presence of goitre. The overall goitre prevalence in coastal areas was 6.3%; 6.0% (4/67) of Aborigines and 6.7% (4/60) of Malays were affected. However, in remote inland areas, the prevalence of goitre was almost 5 times higher compared to coastal areas. The prevalence of goitre was 30.7% in Baling; 30.2% (19/63) Aborigines and 30.8% (92/299) Malays were affected. Iodine deficiency is the most likely cause for the high prevalence of goitre in the remote inland areas.
    Matched MeSH terms: Water/chemistry
  3. Salleh AB, Taib M, Basri M, Ampon K, Yunus WM, Razak CN
    Ann N Y Acad Sci, 1996 Oct 12;799:328-31.
    PMID: 8958097
    Matched MeSH terms: Water/chemistry*
  4. Foo LC, Zainab T, Nafikudin M, Letchuman GR
    Ann Endocrinol (Paris), 1996;57(6):470-5.
    PMID: 9084692
    The urinary iodine excretions of women (15-40 y) and young children (< or = 6 y) from two longhouse villages in the iodine-deficient district of Lubok Antu, Sarawak, were compared. One longhouse (Mengkak) was provided with freshly produced iodized salt every two months (one kg per family) while the other (Menjiling) was provided with iodized water via fortification of the village piped-water supply. Spot urines were collected for iodine determination at baseline and at 6 and 12 months after the start of the study. Salt and water samples were collected at monthly intervals. Goiter assessment was performed on the women at the start and end of the one-year study. The mean iodine concentrations in the salt samples from Mengkak and Menjiling were, respectively, 47.1 +/- 9.7 mg/kg (n = 60) and 0.8 +/- 3.4 mg/kg (n = 60) while the mean iodine concentration in the water samples from Menjiling was 138.6 +/- 43.2 micrograms/L (n = 24); iodine could not be detected in the water samples from Mengkak. There were significant and sustained increases in median urinary iodine excretions of both women and young children in Menjiling; in Mengkak, however, significant and sustained increases in median urinary iodine excretions were observed only in women while the median urinary iodine excretions of children remained essentially unchanged throughout the study period. Goiter prevalences in the women were reduced in both longhouses. The above observations reveal the inadequacy of iodized salt as a vehicle for iodine delivery to young rural Sarawakian children and indicate the need for other means of delivering supplemental iodine to this age group in areas where salt iodization is the only strategy for IDD control. In contrast, iodization of village water supply by itself is adequate in delivering iodine uniformly to the whole community.
    Matched MeSH terms: Water/chemistry
  5. Lau S, Mohamed M, Yen AT, Su'ut S
    Sci Total Environ, 1998 Jun 18;214:113-21.
    PMID: 9646520
    Heavy metals in the aquatic environment have to date come mainly from naturally occurring geochemical materials. However, this has been enhanced by human activity such as gold mining in the case of heavy metal pollution in Sg Sarawak Kanan. The high suspended solid loads in the river have quite efficiently removed most soluble metals from the water and trapped them in the bottom sediment. Three freshwater mollusc species were collected at the point source of the heavy metal pollutants and analysed for the heavy metal contents in their tissues and shells. Two of the mollusc species (Brotia costula and Melanoides tuberculata) are purely freshwater species while the Clithon sp. nr retropictus is able to survive in fresh and brackish water environments. The Brotia costula and the Clithon sp. are the edible species which are sold in the market. Accumulation of As, Cu, Fe, Se and Zn in all the three mollusc species were determined and the level of As in the tissues of Brotia costula and the Clithon sp. was much higher than the permissible level for human consumption. The mollusc species also demonstrated different preferences for the uptake of different metals. Variations in the heavy metal contents in the shell and tissues of the same species were also observed.
    Matched MeSH terms: Fresh Water/chemistry*
  6. Billa N, Yuen KH
    AAPS PharmSciTech, 2000;1(4):E30.
    PMID: 14727895
    The purpose of this research was to study processing variables at the laboratory and pilot scales that can affect hydration rates of xanthan gum matrices containing diclofenac sodium and the rate of drug release. Tablets from the laboratory scale and pilot scale proceedings were made by wet granulation. Swelling indices of xanthan gum formulations prepared with different amounts of water were measured in water under a magnifying lens. Granules were thermally treated in an oven at 60 degrees C, 70 degrees C, and 80 degrees C to study the effects of elevated temperatures on drug release from xanthan gum matrices. Granules from the pilot scale formulations were bulkier compared to their laboratory scale counterparts, resulting in more porous, softer tablets. Drug release was linear from xanthan gum matrices prepared at the laboratory scale and pilot scales; however, release was faster from the pilot scales. Thermal treatment of the granules did not affect the swelling index and rate of drug release from tablets in both the pilot and laboratory scale proceedings. On the other hand, the release from both proceedings was affected by the amount of water used for granulation and the speed of the impeller during granulation. The data suggest that processing variables that affect the degree of wetness during granulation, such as increase in impeller speed and increase in amount of water used for granulation, also may affect the swelling index of xanthan gum matrices and therefore the rate of drug release.
    Matched MeSH terms: Water/chemistry
  7. Ahmed AM, Sulaiman WN
    Environ Manage, 2001 Nov;28(5):655-63.
    PMID: 11568845
    Landfills are sources of groundwater and soil pollution due to the production of leachate and its migration through refuse. This study was conducted in order to determine the extent of groundwater and soil pollution within and around the landfill of Seri Petaling located in the State of Selangor, Malaysia. The condition of nearby surface water was also determined. An electrical resistivity imaging survey was used to investigate the leachate production within the landfill. Groundwater geochemistry was carried out and chemical analysis of water samples was conducted upstream and downstream of the landfill. Surface water was also analyzed in order to determine its quality. Soil chemical analysis was performed on soil samples taken from different locations within and around the landfill in the vadose zone (unsaturated zone) and below the water table (in the soil saturated zone). The resistivity image along line L-L1 indicated the presence of large zones of decomposed waste bodies saturated with highly conducting leachate. Analysis of trace elements indicated their presence in very low concentrations and did not reflect any sign of heavy metal pollution of ground and surface water or of soil. Major ions represented by Na, K, and Cl were found in anomalous concentrations in the groundwater of the downstream bore hole, where they are 99.1%, 99.2%, and 99.4%, respectively, higher compared to the upstream bore hole. Electrical conductivity (EC) was also found in anomalous concentration downstream. Ca and Mg ions represent the water hardness (which is comparatively high downstream). There is a general trend of pollution towards the downstream area. Sulfates (SO4) and nitrates (NO3) are found in the area in low concentrations, even below the WHO standards for drinking water, but are significantly higher in the surface water compared to the groundwater. Phosphate (PO4) and nitrite (NO2), although present in low levels, are significantly higher at the downstream. There is no significant difference in the amount of fluoride (F) in the different locations. In the soil vadose zone, heavy metals were found to be in their typical normal ranges and within the background concentrations. Soil exchangeable bases were significantly higher in the soil saturated zone compared to the vadose zone, and no significant difference was obtained in the levels of inorganic pollutants. With the exception of Cd, the concentration ranges of all trace elements (Cu, Zn, Cr, Pb, and Ni) of Seri Petaling landfill soils were below the upper limits of baseline concentrations published from different sources.
    Matched MeSH terms: Fresh Water/chemistry
  8. Tan YT, Peh KK, Al-Hanba O
    J Pharm Pharm Sci, 2001 Jan-Apr;4(1):7-14.
    PMID: 11302785
    To investigate the interpolymer complexation between Carbopol 934P (CP) and various grades of polyvinylpyrrolidone (PVP) (K90, K32, C15, and VA/S-630).
    Matched MeSH terms: Water/chemistry
  9. Salleh AB, Basri M, Taib M, Jasmani H, Rahman RN, Rahman MB, et al.
    Appl Biochem Biotechnol, 2002 10 25;102-103(1-6):349-57.
    PMID: 12396136
    Recent studies on biocatalysis in water-organic solvent biphasic systems have shown that many enzymes retain their catalytic activities in the presence of high concentrations of organic solvents. However, not all enzymes are organic solvent tolerant, and most have limited and selective tolerance to particular organic solvents. Protein modification or protein tailoring is an approach to alter the characteristics of enzymes, including solubility in organic solvents. Particular amino acids may play pivotal roles in the catalytic ability of the protein. Attaching soluble modifiers to the protein molecule may alter its conformation and the overall polarity of the molecule. Enzymes, in particular lipases, have been chemically modified by attachment of aldehydes, polyethylene glycols, and imidoesters. These modifications alter the hydrophobicity and conformation of the enzymes, resulting in changes in the microenvironment of the enzymes. By these modifications, newly acquired properties such as enhancement of activity and stability and changes in specificity and solubility in organic solvents are obtained. Modified lipases were found to be more active and stable in organic solvents. The optimum water activity (a(w)) for reaction was also shifted by using modified enzymes. Changes in enantioselective behavior were also observed.
    Matched MeSH terms: Water/chemistry
  10. Alongi DM, Chong VC, Dixon P, Sasekumar A, Tirendi F
    Mar Environ Res, 2003 May;55(4):313-33.
    PMID: 12517423
    The impact of floating net cages culturing the seabass, Lates calcarifer, on planktonic processes and water chemistry in two heavily used mangrove estuaries in Malaysia was examined. Concentrations of dissolved inorganic and particulate nutrients were usually greater in cage vs. adjacent (approximately 100 m) non-cage waters, although most variability in water-column chemistry related to water depth and tides. There were few consistent differences in plankton abundance, production or respiration between cage and non-cage sites. Rates of primary production were low compared with rates of pelagic mineralization reflecting high suspended loads coupled with large inputs of organic matter from mangrove forests, fishing villages, fish cages, pig farms and other industries within the catchment. Our preliminary sampling did not reveal any large-scale eutrophication due to the cages. A crude estimate of the contribution of fish cage inputs to the estuaries shows that fish cages contribute only approximately 2% of C but greater percentages of N (32-36%) and P (83-99%) to these waters relative to phytoplankton and mangrove inputs. Isolating and detecting impacts of cage culture in such heavily used waterways--a situation typical of most mangrove estuaries in Southeast Asia--are constrained by a background of large, highly variable fluxes of organic material derived from extensive mangrove forests and other human activities.
    Matched MeSH terms: Water/chemistry*
  11. Halimah M, Tan YA, Aini K, Ismail BS
    J Environ Sci Health B, 2003 Jul;38(4):429-40.
    PMID: 12856925
    Improved methods for extraction and clean up of fluroxypyr residue in water have been established. Two methods of fluroxypyr extraction were used, namely, Direct Measurement of fluroxypyr and Concentration of fluroxypyr onto A Solid Phase Extraction (SPE) Adsorbent, followed by elution with solvent before determination of fluroxypyr. The recovery for Direct Measurement of fluroxypyr in water containing 8-100 microg L(-1), ranged from 86 to 110% with relative standard deviation of 0.7 to 2.15%. For the second method, three types of SPE were used, viz. C18, C18 end-capped and polyvinyl dibenzene (ISOLUTE ENV+). The procedure involved concentrating the analyte from fluroxypyr-spiked water at pH 3, followed by elution of the analyte with 4 mL of acentonitrile. The recovery of fluroxypyr from the spiked sample at 1 to 50 microg L(-1) after eluting through either C18 or C18 end-capped ranged from 40-64% (with relative standard deviation of 0.7 to 2.15) and 41-65% (with standard deviation of 1.52 to 11.9). The use of ISOLUTE ENV+, gave better results than the C18, C18 end-capped or the Direct Measurement Methods. The recovery and standard deviation of fluroxypyr from spiked water using ISOLUTE ENV+ ranged from 91-102% and 2.5 to 5.3, respectively.
    Matched MeSH terms: Water/chemistry*
  12. Isobe KO, Zakaria MP, Chiem NH, Minh le Y, Prudente M, Boonyatumanond R, et al.
    Water Res, 2004 May;38(9):2448-58.
    PMID: 15142807
    This paper reports the result of sewage pollution monitoring conducted in South and Southeast Asia during 1998-2003 using linear alkylbenzenes (LABs) as molecular tracers of sewage contamination. Eighty-nine water samples collected from Malaysia, Vietnam, and Japan (Tokyo), and 161 surface sediment samples collected from Tokyo, Thailand, Malaysia, Philippines, Vietnam, Cambodia, Indonesia, and India were analyzed for alkylbenzenes. The concentration range of SigmaLABs in river water particles in Southeast Asia (<0.005-0.913 microg/L) was comparable to or higher than those found in Tokyo (<0.005-0.638 microg/L). I/E ratios (a ratio of internal to external isomers of LABs) in tropical Asian waters were close to the value of LABs in raw sewage ( approximately 1) and much lower than those in secondary effluents (3-5). This suggests that untreated or inadequately treated sewage is discharged into the water. SigmaLABs concentrations in sediments from South and Southeast Asia ranged from <0.002-42.6 microg/g-dry with the highest concentration occurring at several populous cities. Low I/E ratios of the sediments with high SigmaLABs concentrations suggest a heavy load of untreated sewage. Clearly in view of the current data and evidence of the implications of sewage pollution, this paper highlights the necessity of the continuation of water treatment system improvement in tropical Asia.
    Matched MeSH terms: Fresh Water/chemistry
  13. Ngah WS, Ab Ghani S, Kamari A
    Bioresour Technol, 2005 Mar;96(4):443-50.
    PMID: 15491825
    A batch adsorption system was applied to study the adsorption of Fe(II) and Fe(III) ions from aqueous solution by chitosan and cross-linked chitosan beads. The adsorption capacities and rates of Fe(II) and Fe(III) ions onto chitosan and cross-linked chitosan beads were evaluated. Chitosan beads were cross-linked with glutaraldehyde (GLA), epichlorohydrin (ECH) and ethylene glycol diglycidyl ether (EGDE) in order to enhance the chemical resistance and mechanical strength of chitosan beads. Experiments were carried out as function of pH, agitation period, agitation rate and concentration of Fe(II) and Fe(III) ions. Langmuir and Freundlich adsorption models were applied to describe the isotherms and isotherm constants. Equilibrium data agreed very well with the Langmuir model. The kinetic experimental data correlated well with the second-order kinetic model, indicating that the chemical sorption was the rate-limiting step. Results also showed that chitosan and cross-linked chitosan beads were favourable adsorbers.
    Matched MeSH terms: Water/chemistry*
  14. Lim PT, Ogata T
    Toxicon, 2005 May;45(6):699-710.
    PMID: 15804519
    Four tropical PSP toxins-producing dinoflagellates, Alexandrium minutum, Alexandrium tamiyavanichii, Alexandrium tamarense and Alexandrium peruvianum from Malaysian waters were studied to investigate the influences of salinity on growth and toxin production. Experiments were conducted on constant temperature 25 degrees C, 140 microE mol m(-2) s(-1) and under 14:10 light:dark photo-cycle with salinity ranged from 2 to 30 psu. The PSP-toxin congeners, GTX 1-6, STX, dcSTX, NEO and C1-C2 were analysed by high performance liquid chromatography. Salinity tolerance of the four species in decreasing order is A. minutum>A. peruvianum>A. tamarense>A. tamiyavanichii. Specific growth rates and maximum densities varied among these species with A. minutum recorded as the highest, 0.5 day(-1) and 6 x 10(4) cells L(-1). Toxin content decreased with elevated salinities in A. minutum, the highest toxin content was about 12 fmole cell(-1) at 5 psu. In A. tamiyavanichii, toxin content peaked at optimal growth salinity (20 and 25 psu). Toxin content of A. tamarense, somehow peaked at sub-optimal growth salinity (15 and 30 psu). Results of this study implied that salinity fluctuation not only influenced the growth physiology but also toxin production of these species.
    Matched MeSH terms: Water/chemistry*
  15. Ismail BS, Maznah Z
    Bull Environ Contam Toxicol, 2005 Oct;75(4):789-96.
    PMID: 16400562
    Matched MeSH terms: Water/chemistry
  16. Siew Tan B, Razak IA
    Community Dent Oral Epidemiol, 2005 Oct;33(5):317-25.
    PMID: 16128790
    The aim of this study was to assess (by direct determination) the fluoride (F) exposure from ingested toothpaste among 4-5-year-old Malaysian children.
    Matched MeSH terms: Water/chemistry
  17. Zainal Z, Hui LK, Hussein MZ, Taufiq-Yap YH, Abdullah AH, Ramli I
    J Hazard Mater, 2005 Oct 17;125(1-3):113-20.
    PMID: 15996813
    The photodegradation of various dyes in aqueous solution was studied. Experiments were carried out using glass coated titanium dioxide thin film as photocatalyst. Photodegradation processes of methylene blue (MB), methyl orange (MO), indigo carmine (IC), chicago sky blue 6B (CSB), and mixed dye (MD, mixture of the four mentioned single dye) were reported. As each photodegradation system is pH dependent, the photodegradation experiment was carried out in each dye photodegradation reactive pH range at approximately 28 degrees C. The dyes removal efficiency was studied and compared using UV-vis spectrophotometer analysis. The total removal of each dye was: methylene blue (90.3%), methyl orange (98.5%), indigo carmine (92.4%), chicago sky blue 6B (60.3%), and mixed dyes (70.1%), respectively. The characteristic of the photocatalyst was investigated using X-ray diffractometer (XRD). The amount of each dye intermediate produced in the photodegradation process was also determined with the help of total organic carbon (TOC) analysis.
    Matched MeSH terms: Water/chemistry*
  18. Abdul-Talib S, Ujang Z, Vollertsen J, Hvitved-Jacobsen T
    Water Sci Technol, 2005;52(3):181-9.
    PMID: 16206858
    A two-stage anoxic transformation process, involving growth of biomass utilizing two types of different electron acceptors, namely nitrate and nitrite, has been observed. The present water quality modules established for sewer processes cannot account for the two-stage process. This paper outlines the development of a model concept that enables the two-stage anoxic transformation process to be simulated. The proposed model is formulated in a matrix form that is similar to the Activated Sludge Models and Sewer Process Model matrices. The model was successfully applied to simulate changes in nitrate and nitrite concentrations during anoxic transformations in the bulkwater phase of municipal wastewater.
    Matched MeSH terms: Water/chemistry*
  19. Iluyemi FB, Hanafi MM, Radziah O, Kamarudin MS
    Bioresour Technol, 2006 Feb;97(3):477-82.
    PMID: 16216731
    Palm kernel cake (PKC), an agro-industrial by-product used extensively in the animal feed industry, has limited use in fish feeds due to its high fiber and low protein contents. In this study, PKC was processed under solid state culture conditions with five fungal strains and the effect of this fungal culturing on the amino acid, fatty acid, cellulose and hemicellulose fractions was evaluated. Fungal strains used were Sclerotium rolfsii, Trichoderma harzianum, Trichoderma longiobrachiatum, Trichoderma koninggi and Aspergillus niger. Fungal growth was carried out at 50% moisture level and 1% inoculum level for 7 days. A significant increase in protein content from 18.76% to 32.79% was obtained by growing T. longibrachiatum on PKC. Cellulose level decreased significantly from 28.31% to 12.11% for PKC cultured with T. longibrachiatum, and hemicellulose from 37.03% to 19.01% for PKC cultured with A. niger. Fungal culturing of PKC brought about an increase in the level of unsaturated- and a decrease in the level of the saturated-fatty acids.
    Matched MeSH terms: Water/chemistry
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