Displaying publications 81 - 100 of 114 in total

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  1. Mercury contamination in facial skin lightening creams and its health risks to user
    Ho YB, Abdullah NH, Hamsan H, Tan ESS
    Regul Toxicol Pharmacol, 2017 Aug;88:72-76.
    PMID: 28554823 DOI: 10.1016/j.yrtph.2017.05.018
    This study aims to determine concentrations of mercury in facial skin lightening cream according to different price categories (category I:
    Matched MeSH terms: Mercury/analysis*
  2. Estimation and influence of physicochemical properties and chemical fractions of surface sediment on the bioaccessibility of Cd and Hg contaminant in Langat River, Malaysia
    Kadhum SA, Ishak MY, Zulkifli SZ
    Environ Geochem Health, 2017 Oct;39(5):1145-1158.
    PMID: 27848092 DOI: 10.1007/s10653-016-9883-4
    This study applied the use of sequential extraction technique and simple bioaccessibility extraction test to quantify the bioavailable fractions and the human bioaccessible concentration of metals collected from nine stations in surface sediment of the Langat River. The concentrations of total and bioaccessible metals from different stations were in the range of 0.49-1.04, 0.10-0.32 μg g-1 for T-Cd, Bio-Cd, respectively, and 12.9-128.03, 2.06-8.53 μg kg-1 for T-Hg, Bio-Hg, respectively. The results revealed highest R-Bio-Cd in Banting station (55.3 %), while the highest R-Bio-Hg was in Kajang station (49.61 %). The chemical speciation of Cd in most sampling stations was in the order of oxidisable-organic > residual > exchangeable > acid-reducible, while speciation of Hg was in the order of exchangeable > residual > oxidisable-organic > acid-reducible. The correlation matric of mean content showed that the TOM, particle size and Mg++ in polluted surface sediments was highly correlated with total mercury. The PCA showed that the main factors influencing the bioaccessibility of Hg in surface sediments were the sediment TOM, F1 (EFLE) and F3 (oxidation-organic), while the factor influencing the bioaccessibility of Cd was the F3 (oxidation-organic) and T-Cd.
    Matched MeSH terms: Mercury/metabolism*; Mercury/chemistry
  3. Characteristics of Pelargonium radula as a mercury bioindicator for safety assessment of drinking water
    Majid NA, Phang IC, Darnis DS
    Environ Sci Pollut Res Int, 2017 Oct;24(29):22827-22838.
    PMID: 28150147 DOI: 10.1007/s11356-017-8484-9
    Identification of Pelargonium radula as bioindicator for mercury (Hg) detection confers a new hope for monitoring the safety of drinking water consumption. Hg, like other non-essential metals, inflicts the deterioration of biological functions in human and other creatures. In the present study, effects of Hg on the physiology and biochemical content of P. radula were undertaken to understand the occurrence of the morphological changes observed. Young leaves of P. radula were treated with different concentrations of Hg-containing solution (0.5, 1.0 and 2.0 ppb) along with controls for 4 h, prior to further analysis. Elevated Hg concentration in treatment solution significantly prompted an increased accumulation of Hg in the leaf tissues. Meanwhile, total protein, chlorophyll and low molecular mass thiol contents (cysteine, glutathione and oxidized glutathione) decreased as Hg accumulation increased. However, phytochelatin 2 productions were induced in the treated leaves, in comparison to the control. Based on these findings, it is postulated that as low as 0.5 ppb of Hg interferes with the metabolic processes of plant cells, which was reflected from the morphological changes exhibited on P. radula leaves-the colour of the Hg-treated leaves changed from green to yellowish-brown, became chlorosis and wilted. Changes in the tested characteristics of plant are closely related to the Hg-induced morphological changes on P. radula leaves, a potential bioindicator for detecting Hg in drinking water.
    Matched MeSH terms: Mercury/analysis*
  4. Assessment of metallic trace elements in the muscles and fins of four landed elasmobranchs from Kuala Terengganu Waters, Malaysia
    Ong MC, Gan SL
    Mar Pollut Bull, 2017 Nov 30;124(2):1001-1005.
    PMID: 28807418 DOI: 10.1016/j.marpolbul.2017.08.019
    A study had been carried out to determine Cu, Zn, Cd, Hg and Pb concentrations in the muscle and fins of four elasmobranchs species namely spot-tail sharks, milk sharks, whitespotted bamboo sharks and whitespotted guitarfish from Pulau Kambing LKIM Fishery Complex, Kuala Terengganu, Malaysia. Zinc level was found to have the highest concentration whereas Cd had the lowest concentration in both organs. By comparing both organs, metals concentrations in fins of all elasmobranchs species were higher than muscle. Result obtained was compared with the guidelines set by Malaysian Food Regulation and the provisional tolerable weekly intake was also determined. Current study recommends that the muscle of whitespotted bamboo shark from Kuala Terengganu Waters is likely not to be consumed due to it exceeded the allowable consumption guideline. Finding of this paper is very useful as it provides the baseline data on the pollution status of elasmobranchs in Kuala Terengganu Waters.
    Matched MeSH terms: Mercury/analysis
  5. Fulltext Spatial and temporal variation on distributions of dissolved and particulate arsenic and mercury in Sungai Kuantan, Pahang
    Fikriah Faudzi, Mohd Fuad Miskon, Kamaruzzaman Yunus, Mokhlesur Rahman
    Sains Malaysiana, 2017;46:393-399.
    It is important to monitor the concentration of toxic metals in the Sungai Kuantan as it serves many communities in terms of domestic, fisheries and agriculture purpose. In order to determine the distributions of dissolved and particulate As and Hg in Sungai Kuantan and evaluate its changes temporally and spatially, water samples were collected from the surface and bottom layers in a grid of 9 stations from estuary towards the upstream of Sungai Kuantan from May 2012 till October 2012. The dissolved metals were pre-concentrated using Chelex-100 while particulate metals were digested using Teflon bomb and subsequently were analyzed using ICP-MS. Dissolved As ranging from 4.650 to 36.894 µg L-1 while dissolved Hg ranging from BDL to 0.011 µg L-1. Particulate As and Hg varied from 0.650 to 86.087 mg L-1 and BDL to 5.873 mg L-1, respectively. Higher concentration of the dissolved elements were found mainly in October 2012 and particulate elements concentration mostly higher in May 2012. The source of the studied metals in the river may be the run-off from the effluent discharges and other natural sources. The toxic elements studied in Sungai Kuantan waters were still below the Interim Marine Water Quality Standard (INWQS) permissible limits.
    Matched MeSH terms: Mercury
  6. Neutron activation analysis and assessment of trace elements in fingernail from residents of Tokyo, Japan
    Wee B, Ebihara M
    Sains Malaysiana, 2017;46:605-613.
    We report herewith the study of fingernail clippings obtained from the residents of Tokyo, Japan. A total of 18 participants with no health problems and occupational exposure to metals were recruited to provide fingernails samples for this study. Through the use of instrumental neutron activation analysis (INAA), 18 elements (Ag, Al, As, Ca, Cl, Co, Cu, Fe, Hg, K, Mg, Mn, Na, S, Sb, Se, V, and Zn) were determined. The results showed that the toxic elements in the fingernails are in the lower range when compared to literature values. There were no chronic exposures to toxic elements such as As and Hg found. The level of Hg found is lower than that reported 20 years ago, possibly due to the strict regulation control in Japan on the release of Hg to the environment. The elements Se and Zn are found to be rather uniformly distributed among participants and are in agreement with results from other countries. There were no significant differences in elemental concentrations due to genders and smoking habits. The overall data from this study showed similar concentrations to those of healthy participants from other countries. Thus, the current data could represent the background level of elemental concentrations in fingernails of residents in Tokyo, which could serve as reference values for future study.
    Matched MeSH terms: Mercury
  7. Fulltext Drying shrinkage and porosity of polymer modified concrete containing Vinyl Acetate Effluents
    Ainul Haezah Noruzman, Mohammad Ismail, Taliat Ola Yusuf, Parham Forouzani
    Pertanika Journal of Science & Technology, 2017;25(105):217-224.
    MyJurnal
    The volume of waste generated from surface coating industries is of global concern. The disposal of this waste in the form of effluent has put enormous pressure on land and also poses as a health hazard when it leaches into soil and underground water. The study aims to examine the utilization of vinyl acetate effluents from water based paint factories as an admixture in concrete. Concrete specimens containing 0%, 2.5%, 5% and 10% of vinyl acetate effluents by weight of cement were prepared. The specimens were tested for drying shrinkage for 28 days and porosity was tested using mercury intrusion porosimetry. Findings show that concrete containing various proportions of vinyl acetate effluents manifests higher shrinkage behaviour compared to the control item. An investigation of pore size distribution reveals that polymer effluents have particles size larger than 50 nm which are categorize as macroporous in accordance to IUPAC classification. It can be concluded that adding polymer vinyl acetate effluents affects concrete deformation due to the condition of its pore structures. The utilization of this material may provide beneficial effect in terms of the durability performance of concrete and minimize environmental pollution.
    Matched MeSH terms: Mercury
  8. Fulltext Kinetic studies of the partially purified molybdenum-reducing enzyme from Bacillus pumilus strain Lbna
    Abo-Shakeer, L.K.A., Rahman, M.F.A., Yakasai, H., Syed, M.A., Shukor M.Y., Bakar, N.A., et al.
    Bioremediation Science and Technology Research, 2017;5(1):18-23.
    MyJurnal
    Bacterial based remediation of environmental toxicants is a promising innovative technology
    for molybdenum pollution. To date, the enzyme responsible for molybdate reduction to Moblue
    from bacteria show that the Michaelis-Menten constants varies by one order of magnitude.
    It is important that the constants from newer enzyme sources be characterized so that a
    comparison can be made. The aim of this study is to characterize kinetically the enzyme from a
    previously isolated Mo-reducing bacterium; Bacillus pumilus strain Lbna. The maximum
    activity of this enzyme occurred at pH 5.5 and in between 25 and 35 oC. The Km and Vmax of
    NADH were 6.646 mM and 0.057 unit/mg enzyme, while the Km and Vmax of LPPM were 3.399
    mM and 0.106 unit/mg enzyme. The results showed that the enzyme activity for Bacillus
    pumilus strain Lbna were inhibited by all heavy metals used. Zinc, copper, silver, chromium,
    cadmium and mercury all caused more than 50% inhibition to the Mo-reducing enzyme activity
    with copper being the most potent with an almost complete inhibition of enzyme activity
    observed.
    Matched MeSH terms: Mercury
  9. Fulltext Mercury-added products management: challenges in developing countries and lessons learned from medical facility
    Mohamad Mahathir Amir Sultan, Goh CT, Peterson PJ, Sharifah Ezat Wan Puteh, Mazlin Mokhtar
    Malaysian Journal of Public Health Medicine, 2017;17(1):59-68.
    The risks of mercury use have prompted the establishment of Minamata Convention on Mercury which placed strong emphasis on management of mercury-added products. This convention aims to reduce and phase out the use, manufacturing and trade of mercury-added products including batteries, switches and non-electronic measuring devices. This commitment will cause significant impacts especially in the developing countries in designing the right approach to achieve it. This is also true for medical industry which is well known for the utilization of mercury-added devices and dental amalgam in its services but had embarked on efforts in eliminating mercury for many years. The experiences learned within a medical facility can be useful in efforts to meet this global ambition of mercury phase out. This paper aims to provide conceptual discussion on the challenges faced by developing countries and lessons learned from medical facility that can helps the formulation of appropriate approaches to manage mercury-added products. The paper adopted medical industry as a case study and used document analysis to discuss the issue. The main challenges identified for developing countries include lacks of capacity, funding, data and newer technologies. Based on analysis of previous studies, this study proposed a mercury management framework in medical facility and identified the recommended practices, namely technological application, policy instrument, capacity building and guidelines development. These identified approaches are found to have specific relationships between cost and potential impacts, hence giving flexibility for adoption based on the available resources in promoting better mercury management system.
    Matched MeSH terms: Mercury
  10. Evaluation of the neurotoxic effects of chronic embryonic exposure with inorganic mercury on motor and anxiety-like responses in zebrafish (Danio rerio) larvae
    Abu Bakar N, Mohd Sata NS, Ramlan NF, Wan Ibrahim WN, Zulkifli SZ, Che Abdullah CA, et al.
    Neurotoxicol Teratol, 2017 Jan-Feb;59:53-61.
    PMID: 27919701 DOI: 10.1016/j.ntt.2016.11.008
    Chronic exposure to mercury (Hg) can lead to cumulative impairments in motor and cognitive functions including alteration in anxiety responses. Although several risk factors have been identified in recent year, little is known about the environmental factors that either due exposure toward low level of inorganic mercury that may led to the developmental disorders. The present study investigated the effects of embryonic exposure of mercury chloride on motor function and anxiety-like behavior. The embryo exposed to 6 different concentrations of HgCl2 (7.5, 15, 30, 100, 125, 250nM) at 5hpf until hatching (72hpf) in a semi-static condition. The mortality rate increased in a dose dependent manner where the chronic embryonic exposure to 100nM decreased the number of tail coiling, heartbeat, and swimming activity. Aversive stimulus was used to examine the effects of 100nM interferes with the development of anxiety-related behavior. No elevation in both thigmotaxis and avoidance response of 6dpf larvae exposed with 100nM were found. Biochemical analysis showed HgCl2 exposure affects proteins, lipids, carbohydrates and nucleic acids of the zebrafish larvae. These results showed that implication of HgCl2 on locomotor and biochemical defects affects motor performance and anxiety-like responses. Yet, the potential underlying mechanisms these responses need to be further investigated which is crucial to prevent potential hazards on the developing organism due to neurotoxicant exposure.
    Matched MeSH terms: Mercury/toxicity*
  11. Historical atmospheric pollution trends in Southeast Asia inferred from lake sediment records
    Engels S, Fong LSRZ, Chen Q, Leng MJ, McGowan S, Idris M, et al.
    Environ Pollut, 2018 Apr;235:907-917.
    PMID: 29353806 DOI: 10.1016/j.envpol.2018.01.007
    Fossil fuel combustion leads to increased levels of air pollution, which negatively affects human health as well as the environment. Documented data for Southeast Asia (SEA) show a strong increase in fossil fuel consumption since 1980, but information on coal and oil combustion before 1980 is not widely available. Spheroidal carbonaceous particles (SCPs) and heavy metals, such as mercury (Hg), are emitted as by-products of fossil fuel combustion and may accumulate in sediments following atmospheric fallout. Here we use sediment SCP and Hg records from several freshwater lentic ecosystems in SEA (Malaysia, Philippines, Singapore) to reconstruct long-term, region-wide variations in levels of these two key atmospheric pollution indicators. The age-depth models of Philippine sediment cores do not reach back far enough to date first SCP presence, but single SCP occurrences are first observed between 1925 and 1950 for a Malaysian site. Increasing SCP flux is observed at our sites from 1960 onward, although individual sites show minor differences in trends. SCP fluxes show a general decline after 2000 at each of our study sites. While the records show broadly similar temporal trends across SEA, absolute SCP fluxes differ between sites, with a record from Malaysia showing SCP fluxes that are two orders of magnitude lower than records from the Philippines. Similar trends in records from China and Japan represent the emergence of atmospheric pollution as a broadly-based inter-region environmental problem during the 20th century. Hg fluxes were relatively stable from the second half of the 20th century onward. As catchment soils are also contaminated with atmospheric Hg, future soil erosion can be expected to lead to enhanced Hg flux into surface waters.
    Matched MeSH terms: Mercury/analysis
  12. Modified APHA closed-tube reflux colorimetric method for TOC determination in water and wastewater
    Salihu SO, Bakar NKA
    Environ Monit Assess, 2018 May 30;190(6):369.
    PMID: 29850927 DOI: 10.1007/s10661-018-6727-y
    The analysis of total organic carbon (TOC) by the American Public Health Association (APHA) closed-tube reflux colorimetric method requires potassium dichromate (K2Cr2O7), silver sulfate (AgSO4), and mercury (HgSO4) sulfate in addition to large volumes of both reagents and samples. The method relies on the release of oxygen from dichromate on heating which is consumed by carbon associated with organic compounds. The method risks environmental pollution by discharging large amounts of chromium (VI) and silver and mercury sulfates. The present method used potassium monochromate (K2CrO4) to generate the K2Cr2O7 on demand in the first phase. In addition, miniaturizing the procedure to semi microanalysis decreased the consumption of reagents and samples. In the second phase, mercury sulfate was eliminated as part of the digestion mixture through the introduction of sodium bismuthate (NaBiO3) for the removal of chlorides from the sample. The modified method, the potassium monochromate closed-tube colorimetry with sodium bismuthate chloride removal (KMCC-Bi), generates the potassium dichromate on demand and eliminates mercury sulfate. The semi microanalysis procedure leads to a 60% reduction in sample volume and ≈ 33.33 and 60% reduction in monochromate and silver sulfate consumption respectively. The LOD and LOQ were 10.17 and 33.90 mg L-1 for APHA, and 4.95 and 16.95 mg L-1 for KMCC-Bi. Recovery was between 83 to 98% APHA and 92 to 104% KMCC-Bi, while the RSD (%) ranged between 0.8 to 5.0% APHA and 0.00 to 0.62% KMCC-Bi. The method was applied for the UV-Vis spectrometry determination of COD in water and wastewater. Statistics was done by MINITAB 17 or MS Excel 2016. ᅟ Graphical abstract.
    Matched MeSH terms: Mercury/analysis; Mercury Compounds
  13. Characterization of edible bird's nest of different production, species and geographical origins using nutritional composition, physicochemical properties and antioxidant activities
    Quek MC, Chin NL, Yusof YA, Law CL, Tan SW
    Food Res Int, 2018 07;109:35-43.
    PMID: 29803459 DOI: 10.1016/j.foodres.2018.03.078
    Edible bird's nest (EBN) is a precious food made from the solidified saliva of swiftlets. EBN from three types of origin, namely production, swiftlet species and geographical were characterised based on its nutritional composition, physicochemical properties and antioxidant properties. Proximate composition, total phenolic content (TPC) and antioxidant activities were determined following official methods, while mineral and heavy metal contents were obtained by respective atomic adsorption spectrometry (AAS) and inductively coupled plasma-mass spectrometry (ICP-MS). Amino acids profile and sialic acid were determined using high performance liquid chromatography (HPLC). Calcium and sodium were the major elements in EBN samples at averages of 17,267 mg/kg and 13,681 mg/kg, respectively. Despite protein contents were not significantly different; interestingly the total amino acids in A. fuciphagus EBN, 64.57 g/100 g was found to be 23% higher than in A. maximus EBN. EBN from house, A. fuciphagus and Peninsular Malaysia had greater antioxidant activities, 2.33-3.49 mg AAE/g and higher sialic acid, 13.57 g/100 g while those from cave, A. maximus and East Malaysia contained more minerals like calcium and magnesium. The 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity and ferric ion reducing antioxidant power (FRAP) of house, A. fuciphagus and Peninsular Malaysia EBNs were approximately 2 times greater than the others. All samples were complied with the Malaysian Standard MS 2334:2011, except for mercury and nitrite. The overall findings suggest that the quality of EBN was varied following the production, species and geographical origins.
    Matched MeSH terms: Mercury
  14. Toxic metals in Perna viridis mussel and surface seawater in Pasir Gudang coastal area, Malaysia, and its health implications
    Mahat NA, Muktar NK, Ismail R, Abdul Razak FI, Abdul Wahab R, Abdul Keyon AS
    Environ Sci Pollut Res Int, 2018 Oct;25(30):30224-30235.
    PMID: 30155632 DOI: 10.1007/s11356-018-3033-8
    Contamination of toxic metals in P. viridis mussels has been prevalently reported; hence, health risk assessment for consuming this aquaculture product as well as the surrounding surface seawater at its harvesting sites appears relevant. Since Kampung Pasir Puteh, Pasir Gudang is the major harvesting site in Malaysia, and because the last heavy metal assessment was done in 2009, its current status remains unclear. Herein, flame atomic absorption spectrometry and flow injection mercury/hydride system were used to determine the concentrations of Pb, Cd, Cu and total Hg in P. viridis mussels and surface seawater (January-March 2015), respectively. Significantly higher concentrations of these metals were found in P. viridis mussels (p 
    Matched MeSH terms: Mercury/analysis
  15. Mercury Bioaccumulation in Tropical Mangrove Wetland Fishes: Evaluating Potential Risk to Coastal Wildlife
    Le DQ, Satyanarayana B, Fui SY, Shirai K
    Biol Trace Elem Res, 2018 Dec;186(2):538-545.
    PMID: 29577182 DOI: 10.1007/s12011-018-1313-2
    The present study, aimed at observing the total concentration of mercury (Hg) in edible finfish species with an implication to human health risk, was carried out from the Setiu mangrove wetlands on the east coast of Peninsular Malaysia. Out of 20 species observed, the highest Hg concentrations were found among carnivores-fish/invertebrate-feeders, followed by omnivores and carnivores-invertebrate-feeders, while the lowest concentrations in herbivores. The Hg concentrations varied widely with fish species and body size, from 0.12 to 2.10 mg/kg dry weight. A positive relationship between body weight and Hg concentration was observed in particular for Toxotes jaculatrix and Tetraodon nigroviridis. Besides the permissible range of Hg concentration up to 0.3 mg/kg (cf. United States Environmental Protection Agency (USEPA)) in majority of species, the carnivore feeders such as Acanthopagrus pacificus, Gerres filamentosus, and Caranx ignobilis have shown excess amounts (> 0.40 mg/kg flesh weight) that raising concerns over the consumption by local people. However, the weekly intake of mercury-estimated through the fish consumption in all three trophic levels-suggests that the present Hg concentrations are still within the range of Provisional Tolerable Weekly Intake (PTWI) reported by the Joint FAO/WHO Expert Committee on Food Additives (JECFA). Perhaps, a multi-species design for Hg monitoring at Setiu wetlands would be able to provide further insights into the level of toxicity transfer among other aquatic organisms and thereby a strong health risk assessment for the local communities.
    Matched MeSH terms: Mercury/analysis*
  16. Fulltext Occupational safety and health practice in school's classroom in Malaysia
    Noor Adilah Hamzah, Ahmad Rasdan Ismail, Nor Kamilah Makhtar, Khairul Azhar Mat Daud, Norhidayah Mat Sout
    Journal of Occupational Safety and Health, 2018;15(2):13-22.
    MyJurnal
    Today, more accidents reported in school, resulting not only minor injuries but also severe injuries such as fire in schools, mercury spills and falling from high places. The study was aimed at measuring the level of occupational safety and health practices in schools. The study was conducted at 205 schools in Kelantan, Malaysia. This study is a semi-quantitative study using observation method. Data collection is conducted based on Hazard Identification, Risk Assessment and Risk Control (HIRARC) Guidelines provided by the Department of Occupational Safety and Health, Malaysia. Hazard identification, risk assessment and risk control are determined using the HIRARC form. The findings were measured by determining the discrete data according to the number of low, medium and high-risk levels found. The study found that there were two dominant hazards namely physical hazard and ergonomic hazard. Therefore, the management should increase and improve classroom safety awareness to ensure safety and health of all occupants.
    Matched MeSH terms: Mercury
  17. Fulltext Evaluation of porogen factors for the preparation of ion imprinted polymer monoliths used in mercury removal
    Rahman SKA, Yusof NA, Abdullah AH, Mohammad F, Idris A, Al-Lohedan HA
    PLoS One, 2018;13(4):e0195546.
    PMID: 29649325 DOI: 10.1371/journal.pone.0195546
    In the present study, ion imprinted polymer monoliths (IIPMs) were developed to overcome the limitations of ion imprinted polymer particles (IIPPs) used for the removal of Hg(II) ions from waste water samples. The adsorbents preparation, characterization and Hg(II) removal were very well reported. The IIPMs on porogen optimization was prepared using the molding technique with Hg(II) as a template ion, [2-(methacryloyloxy)ethyl]trimethylammonium cysteine (MAETC) as ligand, methacrylic acid (MAA) as functional monomer, ethylene glycol dimethacrylamide (EGDMA) as cross-linker, benzoyl peroxide as an initiator and methanol and acetonitrile as porogen in the polypropylene tube (drinking straw) as mold. The IIPMs prepared with higher volumes of porogen were indicated to have a good adsorption rate for the Hg(II) removal along with good water permeability and larger porosity as compared to a lower volume of porogen. The IIPMs prepared using the binary porogen were able to improve the porosity and surface area of the monolithic polymers as compared to the single porogen added IIPMs. Finally, we indicate from our analysis that the IIPM having the efficient capacity for the Hg(II) ions is easy to prepare, and has higher water permeability along with high porosity and high adsorption capacity and all these factors making it one of the suitable adsorbent for the successful removal of Hg(II) ions.
    Matched MeSH terms: Mercury/isolation & purification*; Mercury/chemistry*
  18. Fulltext Isolation and characterization of a heavy metal-reducing Pseudomonas sp. strain Dr.Y Kertih with the ability to assimilate phenol and diesel
    Veeraswamy Kesavan, Abdulrasheed Mansur, Mohd Syahmi Ramzi Salihan, Rahman, M.F., Suhaili, Zarizal, Shukor, M.Y.
    Bioremediation Science and Technology Research, 2018;6(1):14-22.
    MyJurnal
    The indiscriminate released of heavy metals and xenobiotics into soils and aquatic bodies
    severely alter soil organisms and the ecosystem. The isolation of xenobiotics degrading
    microorganisms is cost-effective and naturally pleasant approach. Lately, the toxicological effect
    of molybdenum to the spermatogenesis of several organisms has been record. This present study
    is aimed at the isolation and characterization of a bacterium capable of converting molybdenum
    to the colloidal molybdenum blue. Bacteria characterization was performed in a microplate
    format using resting cells. Thus, the reduction process can be employed as a device for
    molybdenum bioremediation. The results of the study revealed an optimum reduction at pH
    between 6.0 and 6.3 and temperatures of between 25 and 40 oC. Similarly, it was also observed
    that a phosphate concentration not greater than 5.0 mM and a sodium molybdate concentration
    at 20 mM was required for reduction. Glucose was observed as the best carbon source to support
    reduction. Following the scanning of molybdenum blue, it revealed an absorption spectrum
    indicating the characteristics of molybdenum blue as a reduced phosphomolybdate. Molybdenum
    reduction is inhibited by heavy metals like silver, lead, arsenic and mercury. Furthermore, the
    ability of the bacterium (Pseudomonas sp. strain Dr.Y Kertih) to utilize several organic
    xenobiotics such as phenol, acrylamide, nicotinamide, acetamide, iodoacetamide, propionamide,
    acetamide, sodium dodecyl sulfate (SDS) and diesel as electron donor sources for aiding
    reduction or as carbon sources for growth was also examined. Finding showed that none was
    capable of aiding molybdenum reduction, however the bacterium was capable of growing on both
    diesel and phenol as carbon sources. GC analysis was used to confirmed diesel degradation.
    Matched MeSH terms: Mercury
  19. Fulltext Bioremediation and Electricity Generation by Using Open and Closed Sediment Microbial Fuel Cells
    Abbas SZ, Rafatullah M, Khan MA, Siddiqui MR
    Front Microbiol, 2018;9:3348.
    PMID: 30692985 DOI: 10.3389/fmicb.2018.03348
    The industrial contamination of marine sediments with mercury, silver, and zinc in Penang, Malaysia was studied with bio-remediation coupled with power generation using membrane less open (aerated) and closed (non-aerated) sediment microbial fuel cells (SMFCs). The prototype for this SMFC is very similar to a natural aquatic environment because it is not stimulated externally and an oxygen sparger is inserted in the cathode chamber to create the aerobic environment in the open SMFC and no oxygen supplied in the closed SMFC. The open and closed SMFCs were showed the maximum voltage generation 300.5 mV (77.75 mW/m2) and 202.7 mV (45.04 (mW/m2), respectively. The cyclic voltammetry showed the oxidation peak in open SMFCs at +1.9 μA and reduction peak at -0.3 μA but in closed SMFCs oxidation and reduction peaks were noted at +1.5 μA and -1.0 μA, respectively. The overall impedance (anode, cathode and solution) of closed SMFCs was higher than open SMFCs. The charge transfer impedance showed that the rates of substrate oxidation and reduction were very low in the closed SMFCs than open SMFCs. The Nyquist arc indicated that O2 act as electron acceptor in the open SMFCs and CO2 in the closed SMFCs. The highest remediation efficiency of toxic metals [Hg (II) ions, Zn (II) ions, and Ag (I) ions] in the open SMFCs were 95.03%, 86.69%, and 83.65% in closed SMFCs were 69.53%, 66.57%, and 65.33%, respectively, observed during 60-80 days. The scanning electron microscope and 16S rRNA analysis showed diverse exoelectrogenic community in the open SMFCs and closed SMFCs. The results demonstrated that open SMFCs could be employed for the power generation and bioremediation of pollutants.
    Matched MeSH terms: Mercury
  20. Smartphone Assisted Naked Eye Detection of Mercury (II) Ion using Horseradish Peroxidase Inhibitive Assays
    Jamadon NK, Busairi N, Syahir A
    Protein Pept Lett, 2018;25(1):90-95.
    PMID: 29237368 DOI: 10.2174/0929866525666171214111503
    BACKGROUND: Mercury (II) ion, Hg2+ is among the most common pollutants with the ability to affect the environment. The implications of their elevation in the environment are mainly due to the industrialization and urbanization process. Current methods of Hg2+ detection primarily depend on sophisticated and expensive instruments. Hence, an alternative and practical way of detecting Hg2+ ions is needed to go beyond these limitations. Here, we report a detection method that was developed using an inhibitive enzymatic reaction that can be monitored through a smartphone. Horseradish peroxidase (HRP) converted 4-aminoantipyrene (4-AAP) into a red colored product which visible with naked eye. A colorless product, on the other hand, was produced indicating the presence of Hg2+ that inhibit the reaction.

    OBJECTIVES: The aim of this study is to develop a colorimetric sensor to detect Hg2+ in water sources using HRP inhibitive assay. The system can be incorporated with a mobile app to make it practical for a prompt in-situ analysis.

    METHODS: HRP enzyme was pre-incubated with different concentration of Hg2+ at 37°C for 1 hour prior to the addition of chromogen. The mix of PBS buffer, 4-AAP and phenol which act as a chromogen was then added to the HRP enzyme and was incubated for 20 minutes. Alcohol was added to stop the enzymatic reaction, and the change of colour were observed and analyse using UV-Vis spectrophotometer at 520 nm wavelength. The results were then analysed using GraphPad PRISM 4 for a non-linear regression analysis, and using Mathematica (Wolfram) 10.0 software for a hierarchical cluster analysis. The samples from spectroscopy measurement were directly used for dynamic light scattering (DLS) evaluation to evaluate the changes in HRP size due to Hg2+ malfunctionation. Finally, molecular dynamic simulations comparing normal and malfunctioned HRP were carried out to investigate structural changes of the HRP using YASARA software.

    RESULTS: Naked eye detection and data from UV-Vis spectroscopy showed good selectivity of Hg2+ over other metal ions as a distinctive color of Hg2+ is observed at 0.5 ppm with the IC50 of 0.290 ppm. The mechanism of Hg2+ inhibition towards HRP was further validated using a dynamic light scattering (DLS) and molecular dynamics (MD) simulation to ensure that there is a conformational change in HRP size due to the presence of Hg2+ ions. The naked eye detection can be quantitatively determined using a smartphone app namely ColorAssist, suggesting that the detection signal does not require expensive instruments to be quantified.

    CONCLUSION: A naked-eye colorimetric sensor for mercury ions detection was developed. The colour change due to the presence of Hg2+ can be easily distinguished using an app via a smartphone. Thus, without resorting to any expensive instruments that are mostly laboratory bound, Hg2+ can be easily detected at IC50 value of 0.29 ppm. This is a promising alternative and practical method to detect Hg2+ in the environment.

    Matched MeSH terms: Mercury/analysis*
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