Displaying publications 1 - 20 of 84 in total

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  1. Fulltext The extraction of different proteins in selenium enriched peanuts and their antioxidant properties
    Zhao P, Wang Y, Zhang Y, Guo T, Zhang Z, Zhang WJ, et al.
    Saudi J Biol Sci, 2016 May;23(3):353-7.
    PMID: 27081360 DOI: 10.1016/j.sjbs.2015.08.007
    In this study, the selenium enriched peanuts and the different solubility proteins extracted from them were investigated. The dried defatted selenium enriched peanuts (SeP) powder (0.3147 μg/g) had a 2.5-fold higher mean total selenium concentration than general peanuts (GP) power (0.1233 μg/g). The SeP had higher concentration of selenium, manganese and zinc than that of GP, but less calcium. The rate of extraction of protein was 23.39% for peanuts and alkali soluble protein was the main component of protein in SeP, which accounted for 92.82% of total soluble protein and combined selenium was 77.33% of total selenium protein. In different forms of proteins from SeP, the WSePr due to higher concentration of selenium had higher DPPH free-radical scavenging activity, higher reducing activity and longer induction time than other proteins.
    Matched MeSH terms: Manganese
  2. Fulltext Research on Hygiene Based on Fieldwork and Experimental Studies
    Yajima I
    Nihon Eiseigaku Zasshi, 2017;72(1):49-54.
    PMID: 28154361 DOI: 10.1265/jjh.72.49
    Several experimental studies on hygiene have recently been performed and fieldwork studies are also important and essential tools. However, the implementation of experimental studies is insufficient compared with that of fieldwork studies on hygiene. Here, we show our well-balanced implementation of both fieldwork and experimental studies of toxic-element-mediated diseases including skin cancer and hearing loss. Since the pollution of drinking well water by toxic elements induces various diseases including skin cancer, we performed both fieldwork and experimental studies to determine the levels of toxic elements and the mechanisms behind the development of toxic-element-related diseases and to develop a novel remediation system. Our fieldwork studies in several countries including Bangladesh, Vietnam and Malaysia demonstrated that drinking well water was polluted with high concentrations of several toxic elements including arsenic, barium, iron and manganese. Our experimental studies using the data from our fieldwork studies demonstrated that these toxic elements caused skin cancer and hearing loss. Further experimental studies resulted in the development of a novel remediation system that adsorbs toxic elements from polluted drinking water. A well-balanced implementation of both fieldwork and experimental studies is important for the prediction, prevention and therapy of toxic-element-mediated diseases.
    Matched MeSH terms: Manganese/adverse effects; Manganese/analysis
  3. A three-step process of manganese acquisition and storage in the microalga Chlorella sorokiniana
    Vojvodić S, Dimitrijević M, Žižić M, Dučić T, Aquilanti G, Stanić M, et al.
    J Exp Bot, 2023 Feb 05;74(3):1107-1122.
    PMID: 36453904 DOI: 10.1093/jxb/erac472
    Metabolism of metals in microalgae and adaptation to metal excess are of significant environmental importance. We report a three-step mechanism that the green microalga Chlorella sorokiniana activates during the acquisition of and adaptation to manganese (Mn), which is both an essential trace metal and a pollutant of waters. In the early stage, Mn2+ was mainly bound to membrane phospholipids and phosphates in released mucilage. The outer cell wall was reorganized and lipids were accumulated, with a relative increase in lipid saturation. Intracellular redox settings were rapidly altered in the presence of Mn excess, with increased production of reactive oxygen species that resulted in lipid peroxidation and a decrease in the concentration of thiols. In the later stage, Mn2+ was chelated by polyphosphates and accumulated in the cells. The structure of the inner cell wall was modified and the redox milieu established a new balance. Polyphosphates serve as a transient Mn2+ storage ligand, as proposed previously. In the final stage, Mn was stored in multivalent Mn clusters that resemble the structure of the tetramanganese-calcium core of the oxygen-evolving complex. The present findings elucidate the bioinorganic chemistry and metabolism of Mn in microalgae, and may shed new light on water-splitting Mn clusters.
    Matched MeSH terms: Manganese/metabolism
  4. Bioavailability and mobility of arsenic, cadmium, and manganese in gold mine tailings amended with rice husk ash and Fe-coated rice husk ash
    Tariq FS, Samsuri AW, Karam DS, Aris AZ, Jamilu G
    Environ Monit Assess, 2019 Mar 21;191(4):232.
    PMID: 30900076 DOI: 10.1007/s10661-019-7359-6
    This study was conducted to determine the effects of rice husk ash (RHA) and Fe-coated rice husk ash (Fe-RHA) on the bioavailability and mobility of As, Cd, and Mn in mine tailings. The amendments were added to the tailings at 0, 5, 10, or 20% (w/w) and the mixtures were incubated for 0, 7, 15, 30, 45, and 60 days. The CaCl2 extractable As, Cd, and Mn in the amended tailings were determined at each interval of incubation period. In addition, the tailings mixture was leached with simulated rain water (SRW) every week from 0 day (D 0) until day 60 (D 60). The results showed that both RHA and Fe-RHA application significantly decreased the CaCl2-extractable Cd and Mn but increased that of As in the tailings throughout the incubation period. Consequently, addition of both RHA and Fe-RHA leached out higher amount of As from the tailings but decreased Cd and Mn concentration compared to the controls. The amount of As leached from the Fe-RHA-amended tailings was less than that from RHA-amended tailings. Application of both RHA and Fe-RHA could be an effective way in decreasing the availability of cationic heavy metals (Cd and Mn) in the tailings but these amendments could result in increasing the availability of anionic metalloid (As). Therefore, selection of organic amendments to remediate metal-contaminated tailings must be done with great care because the outcomes might be different among the elements.
    Matched MeSH terms: Manganese/analysis; Manganese/chemistry
  5. Performance of quartz crystal microbalance gas sensors using thin films of titanium dioxide, porphyrin and titanium dioxide coated with dye porphyrin
    Syariena Arshad, Salleh M, Yahaya M
    Sains Malaysiana, 2008;37:233-237.
    Titanium dioxide (TiO2), porphyrin and TiO2 coated with dye porphyrin thin films were prepared on Quartz Crystal Microbalance (QCM) using sol-gel dip coating method and were tested for sensing of volatile organic compounds (VOCs). The porphyrin used was 5,10,15,20-tetraphenyl-21H,23H-porphine manganese (III) chloride (MnTPPCl). The sensing sensitivity was based on the change in the fundamental frequency of the QCM upon exposure towards six vapor samples, namely ethanol, acetone, cyclohexane, toluene, o-xylene and 2-propanol. It was found that all the thin films were sensitive towards all the vapors. However, the TiO2 coated MnTPPCl thin film exhibit the most sensitive and has good selectivity property.
    Matched MeSH terms: Manganese
  6. Fulltext Pittosporum peridoticola (Pittosporaceae), a new ultramafic obligate species restricted to Kinabalu Park (Sabah, Malaysia)
    Sugau JB, van der Ent A
    Bot Stud, 2015 Dec;57(1):4.
    PMID: 28510789 DOI: 10.1186/s40529-016-0119-9
    BACKGROUND: Kinabalu Park, in Sabah (Malaysia) on Borneo Island, is renowned for the exceptionally high plant diversity it protects, with at least 5000 plant species enumerated to date. Discoveries of plant novelties continue to be made in Sabah, especially on isolated ultramafic outcrops, including in the genus Pittosporum (Pittosporaceae) with P. linearifolium from Bukit Hampuan on the southern border of the Park, and P. silamense from Bukit Silam in Eastern Sabah, both narrow endemics restricted to ultramafic soils.

    RESULTS: A distinctive new species of Pittosporum (P. peridoticola J.B.Sugau and Ent, sp. nov.) was discovered on Mount Tambuyukon in the north of Kinabalu Park during ecological fieldwork. The diagnostic morphological characters of this taxon are discussed and information about the habitat in which it grows is provided. The soil chemistry in the rooting zone of P. peridoticola has high magnesium to calcium quotients, high extractable nickel and manganese concentrations, but low potassium and phosphorus concentrations, as is typical for ultramafic soils. Analysis of foliar samples of various Pittosporum-species originating from ultramafic and non-ultramafic soils showed a comparable foliar elemental stoichiometry that is suggestive of 'Excluder-type' ecophysiology.

    CONCLUSION: Pittosporum peridoticola is an ultramafic obligate species restricted to Kinabalu Park with only two known populations within the boundaries of the protected area. It is vulnerable to any future stochastic landscape disturbance events, such as forest fires or severe droughts, and therefore its conservation status is 'Near Threatened'.

    Matched MeSH terms: Manganese
  7. The chemical, heavy metal and microbial quality of well water in an urbanised village in the Klang Valle
    Stephen Ambu, Stacey Foong Yee Yong, Yvonne Ai Lian Lim, Mak Joon Wah, Donald Koh Fook Chen, Soo Shen Ooi, et al.
    International e-Journal of Science, Medicine & Education, 2014;8(3):28-44.
    MyJurnal
    Background: The public health issue of consuming groundwater is a major concern because people often extract groundwater directly from the aquifers either through wells or boreholes without treating it with any form of filtration system or chlorine disinfection. Based on the Malaysian National Drinking Water guidelines the current study was designed to provide a better understanding on the variable factors that are influencing the quality of well-water in an urbanised village in Malaysia. Well water quality assessment of heavy metals, chemicals, microbial and physical parameters were carried out for Sungai Buloh Village in the Klang Valley to ensure it was safe for human consumption.

    Materials and Methods: Water samples were collected from wells at four sites (Sites A,B,C,D), a river and a tap inside a house in Sungai Buloh village. Soil was sampled from the riverbed and area surrounding the wells. Samples were collected every two months over a one year duration from all sites. The water samples were processed and examined for viruses, coliforms and protozoa as well as for heavy metal contaminants.

    Results: The turbidity and colour ranged in the average of 0.57-0.13 Nephelometric Turbidity (NTU) and 4.16-5.00 Total Conjunctive Use (TCU) respectively for all sites except Site C. At Site C the turbidity level was 2.56 ± 1.38 NTU. The well-water was polluted with coliforms (1.2 to 2.4 x 103 CFU/100 ml) in all sites, E. coli (0.12 - 4 x 102 CFU/100 ml CFU/ 100 ml) and Cryptosporidium oocysts (0.4 cysts/100 ml). All the heavy metals and chemical parameters were within the Malaysian Guidelines’ limits except manganese. The average pH ranged from 5.44 - 6.62 and the temperature was 28 ºC.

    Conclusion: In summary, the well water at Sungai Buloh is considered unsafe for consumption due to pollution. Therefore the major thrust will be to provide better quality of drinking water to the residents of the village.
    Matched MeSH terms: Manganese
  8. Fulltext Effect of acetone extract from stem bark of Acacia species (A. dealbata, A. ferruginea and A. leucophloea) on antioxidant enzymes status in hydrogen peroxide-induced HepG2 cells
    Sowndhararajan K, Hong S, Jhoo JW, Kim S, Chin NL
    Saudi J Biol Sci, 2015 Nov;22(6):685-91.
    PMID: 26586994 DOI: 10.1016/j.sjbs.2015.03.010
    Acacia species are multipurpose trees, widely used in the traditional systems of medicine to treat various ailments. The major objective of the present study was to determine the gene expression of enzymatic antioxidants by acetone extract from the stem bark of three Acacia species (Acacia dealbata, Acacia ferruginea and Acacia leucophloea) in hydrogen peroxide (H2O2)-induced human hepatoma (HepG2) cells. The expression of antioxidant enzymes such as superoxide dismutase containing copper-zinc (CuZnSOD)/manganese (MnSOD), catalase (CAT) and glutathione peroxidase (GPx) in HepG2 cells was evaluated by real-time PCR. The results of antioxidant enzyme expression in real-time PCR study revealed that the H2O2 (200 μM) challenged HepG2 cells reduced the expression of enzymes such as SOD, GPx and CAT. However, the cells pre-treated with acetone extracts of all the three Acacia species significantly (P > 0.05) up-regulated the expression of antioxidant enzymes in a concentration dependent manner (25, 50 and 75 μg/mL). In conclusion, the findings of our study demonstrated that the acetone extract of Acacia species effectively inhibited H2O2 mediated oxidative stress and may be useful as a therapeutic agent in preventing oxidative stress mediated diseases.
    Matched MeSH terms: Manganese
  9. Fulltext Physicochemical properties and water quality parameter of paddy soil and water and their relationship with pesticides concentration
    Siti Zulfa Zaidon, Yu Bin Ho, Zailina Hashim, Nazamid Saari, Sarva Mangala Praveena
    Malaysian Journal of Medicine and Health Sciences, 2020;16(2):206-214.
    MyJurnal
    Introduction: Pesticides may influence the physicochemical properties of soil and the water quality parameters, which is vital in maintaining soil fertility and producing high quality crops. Objective: This study aims to determine the relationship between the concentration of pesticides, the physicochemical properties of the paddy soil samples and the water quality parameters of paddy water samples. Methods: A total of 72 soil and 72 water samples were collected in Tanjung Karang, Malaysia. The paddy soil and water were extracted using Quick, Easy, Cheap, Efficient, Rugged and Safe (QuEChERS) and solid phase extraction (SPE) techniques respectively. The concentrations of pesti- cides were analysed in ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). The relationship of the concentration of target pesticides and the paddy soil and water physicochemical properties were studied using Spearman correlation. Results: In paddy soil, the concentration of propiconazole shows moderate positive correlation with manganese (Mn) (r = 0.587) (p 0.01). Meanwhile buprofezin-total organic carbon (TOC) (r = -0.55) (p 0.01), imidacloprid-cation exchange capacity (CEC) (r = -0.519) (p 0.01), pymetrozine-sodium (Na) (r = -0.588) (p 0.01), and trifloxystrobin-calcium (Ca) (r = 0.566) (p 0.01) showed moderate negative correlation. Whereas in water, trifloxystrobin showed significant positive correlation with turbidity (r = 0.718) (p 0.01) and te- buconazole showed negative correlation to dissolved oxygen (DO) (r = 0.634) (p 0.01). Conclusion: The presence of pesticides in paddy field may influence the soil and water quality, thus regular monitoring of pesticides usage and nutrient management in soil is deemed important.
    Matched MeSH terms: Manganese
  10. Trend in metals variation in Tasik Chini, Pahang, Peninsular Malaysia
    Shuhaimi-Othman M, Mushrifah I, Lim EC, Ahmad A
    Environ Monit Assess, 2008 Aug;143(1-3):345-54.
    PMID: 17987397
    Water from 15 sampling stations in Tasik Chini (Chini Lake), Peninsular Malaysia were sampled for 12 months from September 2004 until August 2005 and analyzed for 11 metals including iron (Fe), aluminum (Al), manganese (Mn), barium (Ba), zinc (Zn), lead (Pb), copper (Cu), cadmium (Cd), nickel (Ni), chromium (Cr) and cobalt (Co). Results showed that the mean (min-max) metal concentrations (in micrograms per liter) in Tasik Chini waters for the 12 months sampling based on 15 sampling stations (in descending order) for Fe, Al, Mn, Ba, Zn, Pb, Cu and Cd were 794.84 (309.33-1609.07), 194.53 (62.37-665.93), 29.16 (16.68-79.85), 22.07 (15.64-29.71), 5.12 (2.224-6.553), 2.36 (1.165-4.240), 0.832 (0.362-1.443) and 0.421 (0.254-0.696) respectively. Concentration for three metals i.e. Ni, Cr and Co were too low and not detected by the graphite furnace Atomic Absorption Spectrophotometry (AAS). Comparison with various water quality standards showed that the mean metals concentration in surface water of Tasik Chini were low and within the range of natural background except for Fe and Al. In general, metal concentrations in Tasik Chini water varied temporally and spatially. The main factors influencing these metal concentrations in the water were the raining season and mining activities. Stations located at Tanjung Jerangking and Melai areas were the most effected due to those factors.
    Matched MeSH terms: Manganese/analysis
  11. Deriving freshwater quality criteria for copper, cadmium, aluminum and manganese for protection of aquatic life in Malaysia
    Shuhaimi-Othman M, Nadzifah Y, Nur-Amalina R, Umirah NS
    Chemosphere, 2013 Mar;90(11):2631-6.
    PMID: 23246727 DOI: 10.1016/j.chemosphere.2012.11.030
    Freshwater quality criteria for copper (Cu), cadmium (Cd), aluminum (Al), and manganese (Mn) were developed with particular reference to aquatic biota in Malaysia, and based on USEPA's guidelines. Acute toxicity tests were performed on eight different freshwater domestic species in Malaysia, which were Macrobrachiumlanchesteri (prawn), two fish -Poeciliareticulata and Rasborasumatrana, Melanoidestuberculata (snail), Stenocyprismajor (ostracod), Chironomusjavanus (midge larvae), Naiselinguis (annelid), and Duttaphrynusmelanostictus (tadpole), to determine 96-h LC50 values for Cu, Cd, Al, and Mn. The final acute values (FAVs) for Cu, Cd, Al, and Mn were 2.5, 3.0, 977.8, and 78.3 μgL(-1), respectively. Using an estimated acute-to-chronic ratio (ACR) of 8.3, the value for final chronic value (FCV) was derived. Based on FAV and FCV, a Criterion Maximum Concentration (CMC) and a criterion Continuous Concentration (CCC) for Cu, Cd, Al, and Mn of 1.3, 1.5, 488.9, and 39.1 μgL(-1) and 0.3, 0.36, 117.8, and 9.4 μgL(-1), respectively, were derived. The results of this study provide useful data for deriving national or local water quality criteria for Cu, Cd, Al, and Mn based on aquatic biota in Malaysia. Based on LC50 values, this study indicated that R.sumatrana, M.lanchesteri, C.javanus, and N.elinguis were the most sensitive to Cu, Cd, Al, and Mn, respectively.
    Matched MeSH terms: Manganese/toxicity
  12. Comparative toxicity of eight metals on freshwater fish
    Shuhaimi-Othman M, Yakub N, Ramle NA, Abas A
    Toxicol Ind Health, 2015 Sep;31(9):773-82.
    PMID: 23302712 DOI: 10.1177/0748233712472519
    Two freshwater fish, Rasbora sumatrana (Cyprinidae) and Poecilia reticulata (guppy; Poeciliidae), were exposed to a range of eight heavy metals (copper (Cu), cadmium (Cd), zinc (Zn), lead (Pb), nickel (Ni), iron (Fe), aluminium (Al), and manganese (Mn)) at varied concentrations for 96 h in the laboratory. Mortality was assessed and median lethal concentrations (LC50) were calculated. It was observed that the LC50 values increased with a decrease in mean exposure times, for all metals and for both fish types. The 96-h LC50 values for Cu, Cd, Zn, Pb, Ni, Fe, Al, and Mn were 0.006, 0.10, 0.46, 0.63, 0.83, 1.71, 1.53, and 5.71 mg/L for R. sumatrana and 0.038, 0.17, 1.06, 1.99, 15.62, 1.46, 6.76, and 23.91 mg/L for P. reticulata, respectively. The metal toxicity trend for R. sumatrana and P. reticulata from most to least toxic was Cu > Cd > Zn > Pb > Ni > Al > Fe > Mn and Cu > Cd > Zn > Fe > Pb > Al > Ni > Mn, respectively. Results indicated that Cu was the most toxic metal on both fish, and R. sumatrana was more sensitive than P. reticulata to all the eight metals.
    Matched MeSH terms: Manganese/analysis; Manganese/toxicity
  13. Fulltext Green synthesis of in situ electrodeposited rGO/MnO2 nanocomposite for high energy density supercapacitors
    Rusi, Majid SR
    Sci Rep, 2015;5:16195.
    PMID: 26537363 DOI: 10.1038/srep16195
    This paper presents the preparation of in situ electrodeposited rGO/MnO2 nanocomposite as a binder-free electrode for supercapacitor application. The work describes and evaluates the performance of prepared electrode via green and facile electrodeposition technique of in situ rGO/MnO2-glucose carbon nanocomposites. The carbon content in the composite electrode increased after GO and D (+) glucose solution has been added in the deposition electrolyte. This study found that a suitable concentration of D (+) glucose in the deposition electrolyte can slow down the nucleation process of MnO2 particles and lead to uniform and ultrathin nanoflakes structure. The optimize electrode exhibited low transfer resistance and resulted on excellent electrochemical performance in three electrolyte systems viz. Na2SO4, KOH and KOH/K3Fe(CN)6 redox electrolytes. The optimum energy density and power density were 1851 Whkg(-1) and 68 kWkg(-1) at current density of 20 Ag(-1) in mixed KOH/K3Fe(CN)6 electrolyte.
    Matched MeSH terms: Manganese Compounds
  14. Fulltext Effects of Electrodeposition Mode and Deposition Cycle on the Electrochemical Performance of MnO2-NiO Composite Electrodes for High-Energy-Density Supercapacitors
    Rusi, Majid SR
    PLoS One, 2016;11(5):e0154566.
    PMID: 27182595 DOI: 10.1371/journal.pone.0154566
    Nanostructured network-like MnO2-NiO composite electrodes were electrodeposited onto stainless steel substrates via different electrodeposition modes, such as chronopotentiometry, chronoamperometry, and cyclic voltammetry, and then subjected to heat treatment at 300°C for metal oxide conversion. X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy were used to study the crystalline natures and morphologies of the deposited films. The electrochemical properties were investigated using cyclic voltammetry and charge/discharge tests. The results revealed that the electrochemical performance of the as-obtained composite electrodes depended on the electrodeposition mode. The electrochemical properties of MnO2-NiO composite electrodes prepared using cyclic voltammetry exhibited the highest capacitance values and were most influenced by the deposition cycle number. The optimum specific capacitance was 3509 Fg-1 with energy and power densities of 1322 Wh kg-1 and 110.5 kW kg-1, respectively, at a current density of 20 Ag-1 in a mixed KOH/K3Fe(CN)6 electrolyte.
    Matched MeSH terms: Manganese Compounds/chemistry*
  15. Fulltext Layer by Layer Ex-Situ Deposited Cobalt-Manganese Oxide as Composite Electrode Material for Electrochemical Capacitor
    Rusi, Chan PY, Majid SR
    PLoS One, 2015;10(7):e0129780.
    PMID: 26158447 DOI: 10.1371/journal.pone.0129780
    The composite metal oxide electrode films were fabricated using ex situ electrodeposition method with further heating treatment at 300°C. The obtained composite metal oxide film had a spherical structure with mass loading from 0.13 to 0.21 mg cm(-2). The structure and elements of the composite was investigated using X-ray diffraction (XRD) and energy dispersive X-ray (EDX). The electrochemical performance of different composite metal oxides was studied by cyclic voltammetry (CV) and galvanostatic charge-discharge (CD). As an active electrode material for a supercapacitor, the Co-Mn composite electrode exhibits a specific capacitance of 285 Fg(-1) at current density of 1.85 Ag(-1) in 0.5 M Na2SO4 electrolyte. The best composite electrode, Co-Mn electrode was then further studied in various electrolytes (i.e., 0.5 M KOH and 0.5 M KOH/0.04 M K3Fe(CN) 6 electrolytes). The pseudocapacitive nature of the material of Co-Mn lead to a high specific capacitance of 2.2 x 10(3) Fg(-1) and an energy density of 309 Whkg(-1) in a 0.5 M KOH/0.04 M K3Fe(CN) 6 electrolyte at a current density of 10 Ag(-1). The specific capacitance retention obtained 67% of its initial value after 750 cycles. The results indicate that the ex situ deposited composite metal oxide nanoparticles have promising potential in future practical applications.
    Matched MeSH terms: Manganese Compounds/chemistry*
  16. Evolution of adsorption process for manganese removal in water via agricultural waste adsorbents
    Rudi NN, Muhamad MS, Te Chuan L, Alipal J, Omar S, Hamidon N, et al.
    Heliyon, 2020 Sep;6(9):e05049.
    PMID: 33033772 DOI: 10.1016/j.heliyon.2020.e05049
    Manganese has recently been a topic of interest among researchers, particularly when 1,752 million tonnes of manganese are expected to be produced by the steel industry in 2020. Manganese discharges from industrial effluents have increased manganese contamination in water sources. Its concentrations of more than 0.2 mg/L in the water sources could have negative impacts on human health and the aquatic ecosystem. Thereby, the available water treatment processes face challenges in effectively removing manganese at low cost. In response to these challenges, adsorption has emerged as one of the most practical water treatment processes for manganese removal. In particular, agricultural waste adsorbents received a lot of attention owing to their low cost and high efficiency (99%) in the removal of manganese. Therefore, this paper reviews the removal of manganese by adsorption process using agricultural waste adsorbents. The factors affecting the adsorption process, the mechanisms, and the performances of the adsorbents are elucidated in detail.
    Matched MeSH terms: Manganese
  17. Fulltext Photopyroelectric spectroscopic studies of ZnO-MnO(2)-Co(3)O(4)-V(2)O(5) ceramics
    Rizwan Z, Zakaria A, Ghazali MS
    Int J Mol Sci, 2011;12(3):1625-32.
    PMID: 21673911 DOI: 10.3390/ijms12031625
    Photopyroelectric (PPE) spectroscopy is a nondestructive tool that is used to study the optical properties of the ceramics (ZnO + 0.4MnO(2) + 0.4Co(3)O(4) + xV(2)O(5)), x = 0-1 mol%. Wavelength of incident light, modulated at 10 Hz, was in the range of 300-800 nm. PPE spectrum with reference to the doping level and sintering temperature is discussed. Optical energy band-gap (E(g)) was 2.11 eV for 0.3 mol% V(2)O(5) at a sintering temperature of 1025 °C as determined from the plot (ρhυ)(2)versushυ. With a further increase in V(2)O(5), the value of E(g) was found to be 2.59 eV. Steepness factor 'σ(A)' and 'σ(B)', which characterize the slope of exponential optical absorption, is discussed with reference to the variation of E(g). XRD, SEM and EDAX are also used for characterization of the ceramic. For this ceramic, the maximum relative density and grain size was observed to be 91.8% and 9.5 μm, respectively.
    Matched MeSH terms: Manganese Compounds/chemistry*
  18. Fulltext Accumulation and risk assessment of heavy metals employing species sensitivity distributions in Linggi River, Negeri Sembilan, Malaysia
    Razak MR, Aris AZ, Zakaria NAC, Wee SY, Ismail NAH
    Ecotoxicol Environ Saf, 2021 Mar 15;211:111905.
    PMID: 33453636 DOI: 10.1016/j.ecoenv.2021.111905
    The constant increase of heavy metals into the aqueous environment has become a contemporary global issue of concern to government authorities and the public. The study assesses the concentration, distribution, and risk assessment of heavy metals in freshwater from the Linggi River, Negeri Sembilan, Malaysia. Species sensitivity distribution (SSD) was utilised to calculate the cumulative probability distribution of toxicity from heavy metals. The aquatic organism's toxicity data obtained from the ECOTOXicology knowledgebase (ECOTOX) was used to estimate the predictive non-effects concentration (PNEC). The decreasing sequence of hazardous concentration (HC5) was manganese > aluminium > copper > lead > arsenic > cadmium > nickel > zinc > selenium, respectively. The highest heavy metal concentration was iron with a mean value of 45.77 μg L-1, followed by manganese (14.41 μg L-1) and aluminium (11.72 μg L-1). The mean heavy metal pollution index (HPI) value in this study is 11.52, implying low-level heavy metal pollutions in Linggi River. The risk quotient (RQ) approaches were applied to assess the potential risk of heavy metals. The RQ shows a medium risk of aluminium (RQm = 0.1125) and zinc (RQm = 0.1262); a low risk of arsenic (RQm = 0.0122) and manganese (RQm = 0.0687); and a negligible risk of cadmium (RQm = 0.0085), copper (RQm = 0.0054), nickel (RQm = 0.0054), lead (RQm = 0.0016) and selenium (RQm = 0.0012). The output of this study produces comprehensive pollution risk, thus provides insights for the legislators regarding exposure management and mitigation.
    Matched MeSH terms: Manganese
  19. Discrimination of dopamine by an electrode modified with negatively charged manganese dioxide nanoparticles decorated on a poly(3,4 ethylenedioxythiophene)/reduced graphene oxide composite
    Promsuwan K, Soleh A, Saisahas K, Saichanapan J, Kanatharana P, Thavarungkul P, et al.
    J Colloid Interface Sci, 2021 Sep;597:314-324.
    PMID: 33872888 DOI: 10.1016/j.jcis.2021.03.162
    A unique nanocomposite was fabricated using negatively charged manganese dioxide nanoparticles, poly (3,4-ethylenedioxythiophene) and reduced graphene oxide (MnO2/PEDOT/rGO). The nanocomposite was deposited on a glassy carbon electrode (GCE) functionalized with amino groups. The modified GCE was used to electrochemically detect dopamine (DA). The surface morphology, charge effect and electrochemical behaviours of the modified GCE were characterized by scanning electron microscopy, energy dispersive X-ray analysis (EDX), cyclic voltammetry and electrochemical impedance spectroscopy, respectively. The MnO2/PEDOT/rGO/GCE exhibited excellent performance towards DA sensing with a linear range between 0.05 and 135 µM with a lowest detection limit of 30 nM (S/N = 3). Selectivity towards DA was high in the presence of high concentrations of the typical interferences ascorbic acid and uric acid. The stability and reproducibility of the electrode were good. The sensor accurately determined DA in human serum. The synergic effect of the multiple components of the fabricated nanocomposite were critical to the good DA sensing performance. rGO provided a conductive backbone, PEDOT directed the uniform growth of MnO2 and adsorbed DA via pi-pi and electrostatic interaction, while the negatively charged MnO2 provided adsorption and catalytic sites for protonated DA. This work produced a promising biosensor that sensitively and selectively detected DA.
    Matched MeSH terms: Manganese Compounds
  20. Geochemical behaviour and risk assessment of trace elements in a tropical river, Northwest Borneo
    Prabakaran K, Eswaramoorthi S, Nagarajan R, Anandkumar A, Franco FM
    Chemosphere, 2020 Aug;252:126430.
    PMID: 32200178 DOI: 10.1016/j.chemosphere.2020.126430
    By convention, dissolved trace elements in the river water are considered to be the fraction that passes through a 0.45 μm filter. However, several researchers have considered filtration cut-off other than 0.45 μm for the separation of dissolved trace elements from particulate fraction. Recent research indicated that trace elements could exist in particulate form as colloids and natural nanoparticles. Moreover, the trace elements in the continental dust (aerosols) constitute a significant component in their geochemical cycling. Due to their high mobility, the trace elements in the micron and sub-micron scale have biogeochemical significance in the coastal zone. In this context, this study focuses on the highly mobile fraction of trace elements in particulates (<11 μm) and dissolved form in the Lower Baram River. A factor model utilizing trace elements in the dissolved and mobile phase in the particulates (<11 μm) along with water column characteristics and the partition coefficient (Kd) of the trace elements indicated a more significant role for manganese oxyhydroxides in trace element transport. Perhaps, iron oxyhydroxides play a secondary role. The factor model further illustrated the dissolution of aluminium and authigenic clay formation. Except for Fe and Al, the contamination risk of mobile trace elements in particulates (<11 μm) together with dissolved form are within the permissible limits of the Malaysian water quality standards during monsoon (MON) and postmonsoon (POM) seasons.
    Matched MeSH terms: Manganese/analysis
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