Displaying publications 301 - 320 of 403 in total

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  1. Fulltext In vitro antioxidant capacities and antidiabetic properties of phenolic extracts from selected citrus peels
    Lim, S.M., Loh, S.P.
    International Food Research Journal, 2016;23(1):211-219.
    MyJurnal
    This study aims to determine the antioxidant capacities (AC) and antidiabetic properties of
    phenolic extracts (free and bound) from white Tambun pomelo peels, kaffir lime peels, lime
    peels and calamansi peels. AC, total phenolic content (TPC) and antidiabetic properties of
    selected citrus peels extracts were determined spectrophotometrically using 2,2-Diphenyl-1-
    picrylhydrazyl free radical (DPPH) scavenging, ferric-reducing antioxidant power (FRAP),
    Folin-Ciocalteu (FC) and α-amylase and α-glucosidase inhibition assay, respectively. This
    study found that the methanolic extract of kaffir lime showed the best AC with the lowest
    IC50 value of DPPH radical (7.51 ± 0.50 mg/ml) and highest FRAP value [369.48 ± 20.15
    mM Fe (II) E/g DW]. TPC of free phenolic extracts of all citrus peels were significantly (p<
    0.05) higher compared to the bound phenolic extracts with extract of calamansi showed the
    highest TPC. Free- and bound phenolic extract of calamansi also had the highest α-amylase
    inhibition activity (61.79 ± 4.13%; 45.30 ± 5.35%) respectively. The highest inhibitory effect in
    α-glucosidase inhibition assay of free- and bound phenolic extracts were white Tambun pomelo
    (41.06 ± 10.94%) and calamansi (43.99 ± 22.03%) respectively. Hence, the citrus peels could
    be furthered study for their potential in management and/or prevention of diabetes.
    Matched MeSH terms: Oxides
  2. Fulltext Structural and electrical characteristic of BA0.7SR0.3TIO3 with a secondary phase BATI2O5
    Sreekantan, Srimala, Ahmad Fauzi Mohd Noor, Zainal Arifin Ahmad, Radzali Othman, West, Anthony, Sinclair, Derek
    Journal of Nuclear and Related Technologies, 2007;2007(1):115-126.
    MyJurnal
    Barium strontium titanate (Ba0.7Sr0.3TiO3) powder was processed at temperature 80 o C by reacting titania sol in aqueous solutions that contained BaCl2, SrCl2 and NaOH at atmospheric pressure.
    The structural characteristic of the powder and sintered pellet were studied using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) whereas the electrical characteristic was determined via Impedance Spectroscopy (IS) and LCR meter. The synthesized powder was found to have a tetragonal phase after heating at 1300 o C. XRD pattern also showed the presence of secondary phase BaTi2O5 (BT2). The SEM results shows the fine grain size was in the range of 0.2 Pm to 0.4 Pm whereas the large ones are approximately 0.8 Pm to 1.2 Pm The ac response of sample sintered at 1300 o C indicated that three electrically different regions. Element 1 can be assigned as a ferroelectric grain boundary region and it is actually BT2, element 2 as a ferroelectric bulk region and the third element is a conductive core which has a low resistance (200 :) and capacitance value.
    Matched MeSH terms: Oxides
  3. Fulltext Alkaline phosphatase activity assessment of two endodontic materials: a preliminary study
    Rajan, S., Awang, H., Pooi, A.H., Hassan, H., Devi, S.
    Ann Dent, 2008;15(1):5-10.
    MyJurnal
    Objective: An in vitro assessment of MG-63 human osteosarcoma cells' alkaline phosphatase (ALP) activity when in contact with calcium hydroxide powder (CH), paste (CHP) and grey mineral trioxide aggregate (MTA). Methods: MG-63 cells were seeded to the three selected materials for durations of 0.25, 0.5, 1, 24, 48 and 72 hours. BCIP-NBT assay was used and ALP activity quantified using ELISA reader at 410 nm. Results: The overall analysis for ALP activity indicated significant interaction between test materials and control (maintenance medium). Subsequently, the test materials were paired and analysed for initial (0.25, 0.5, 1 hour) and delayed response (24, 48 and 72 hours). During the initial response, CH exhibited an increased ALP activity compared to MTA. This interaction was not dependant on duration. The delayed response exhibited elevated ALP activity with CHP when compared to MTA and CH. The interaction of CHP was dependant on duration. Conclusion: All three materials exhibited increased ALP activity.
    Matched MeSH terms: Oxides
  4. Fulltext Biocompatibility assessment of fabricated melt-derived 45S5 bioactive glass on dental cells proliferation
    Mohd Zain N.S., Tajudin S.S., Mohd Noor S.N.F., Mohamad H.
    Journal of Biomedical and Clinical Sciences, 2016;1(1):26-32.
    MyJurnal
    Thisstudy aim tocharacterize melt-derivedbioactive glass and to determinethe bioactive glass (BG) suitability for dental usagethrough proliferative activity assessment of stem cells from human exfoliated deciduous teeth (SHED)when exposed to bioactive glass conditioned medium. Bioglass 45S5 in mole percentages (46.13% SiO2, 26.91% CaO, 24.35% Na2O and 2.60% P2O5)was synthesizedthrough melt-derived and characterized usingX-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR)to confirm and identify its properties.SHEDwere used to evaluate the biocompatibility of 45S5 by exposing the cells to various concentration of BG-conditioned medium (1-10 mg/ml) using alamarBlue assay. The BG produced has an amorphous structureas shown by XRD analysis. TheSi-O-Si bending, asymmetric Si-O stretching and asymmetricSi-O-Si stretchingbands were observed in the BG structure supporting the presenceof silicate network. For alamarBlue assay, SHED cultured in BG-conditioned medium showed high proliferation rate when subjected to minimal powder content in the DMEM cell culture medium.Hence, it can be concluded that SHED cultured in lower powder content of the BG-conditioned media showedhigh proliferative activity suggesting the potential of the BG for dental usage.
    Matched MeSH terms: Oxides
  5. Tailoring the Properties of Metal Oxide Loaded/KCC-1 toward a Different Mechanism of CO2 Methanation by in Situ IR and ESR
    Shahul Hamid MY, Triwahyono S, Jalil AA, Che Jusoh NW, Izan SM, Tuan Abdullah TA
    Inorg Chem, 2018 May 21;57(10):5859-5869.
    PMID: 29746104 DOI: 10.1021/acs.inorgchem.8b00241
    Nickel (Ni), cobalt (Co), and zinc (Zn) loaded on fibrous silica KCC-1 was investigated for CO2 methanation reactions. Ni/KCC-1 exhibits the highest catalyst performance with a CH4 formation rate of 33.02 × 10-2 molCH4 molmetal-1 s-1, 1.77 times higher than that of Co/KCC-1 followed by Zn/KCC-1 and finally the parent KCC-1. A pyrrole adsorption FTIR study reveals shifting of perturbed N-H stretching decreasing slightly with the addition of metal oxide, suggesting that the basic sites of catalyst were inaccessible due to metal oxide deposition. The strengths of basicity were found to follow sthe equence KCC-1, Ni/KCC-1, Zn/KCC-1, and Co/KCC-1. The data were supported by N2 adsorption desorption analysis, where Co/KCC-1 displayed the greatest reduction in total surface area whereas Ni/KCC-1 displayed the least reduction. The elucidation of difference mechanism pathways has also been studied by in situ IR spectroscopy studies to determine the role of different metal oxides in CO2 methanation. It was discovered that Ni/KCC-1 and Co/KCC-1 follow a dissociative mechanism of CO2 methanation in which the CO2 molecule was dissociated on the surface of the metal oxide before migration onto the catalyst surface. This was confirmed by the evolution of a peak corresponding to carbonyl species (COads) on a metal oxide surface in FTIR spectra. Zn/KCC-1, on the other hand, showed no such peak, indicating associative methanation pathways where a hydrogen molecule interacts with an O atom in CO2 to form COads and OH. These results offers a better understanding for catalytic studies, particularly in the field of CO2 recycling.
    Matched MeSH terms: Oxides
  6. Metal-Polydopamine Framework as an Effective Fluorescent Quencher for Highly Sensitive Detection of Hg(II) and Ag(I) Ions through Exonuclease III Activity
    Ravikumar A, Panneerselvam P, Morad N
    ACS Appl Mater Interfaces, 2018 Jun 20;10(24):20550-20558.
    PMID: 29792319 DOI: 10.1021/acsami.8b05041
    In this paper, we propose a metal-polydopamine (MPDA) framework with a specific molecular probe which appears to be the most promising approach to a strong fluorescence quencher. The MPDA framework quenching ability toward various organic fluorophore such as aminoethylcoumarin acetate, 6-carboxyfluorescein (FAM), carboxyteramethylrhodamine, and Cy5 are used to establish a fluorescent biosensor that can selectively recognize Hg2+ and Ag+ ions. The fluorescent quenching efficiency was sufficient to achieve more than 96%. The MPDA framework also exhibits different affinities with ssDNA and dsDNA. In addition, the FAM-labeled ssDNA was adsorbed onto the MPDA framework, based on their interaction with the complex formed between MPDA frameworks/ssDNA taken as a sensing platform. By taking advantage of this sensor, highly sensitive and selective determination of Hg2+ and Ag+ ions is achieved through exonuclease III signal amplification activity. The detection limits of Hg2+ and Ag+ achieved to be 1.3 and 34 pM, respectively, were compared to co-existing metal ions and graphene oxide-based sensors. Furthermore, the potential applications of this study establish the highly sensitive fluorescence detection targets in environmental and biological fields.
    Matched MeSH terms: Oxides
  7. Cost-Effectiveness of Clinical Pharmacy Education on Infection Management among Patients with Chronic Kidney Disease in an Indonesian Hospital
    Nasution A, Syed Sulaiman SA, Shafie AA
    Value Health Reg Issues, 2013 May;2(1):43-47.
    PMID: 29702851 DOI: 10.1016/j.vhri.2013.02.009
    OBJECTIVES: This study evaluated the clinical and economic impacts of clinical pharmacy education (CPE) on infection management among patients with chronic kidney disease (CKD) stages 4 and 5 in Haji Adam Malik Hospital, Indonesia.

    METHODS: A quasi-experimental economic evaluation comparing CPE impact on 6-month CKD mortality was conducted on the basis of payer perspective. The experimental group (n = 63) received care by health care providers who were given CPE on drug-related problems and dose adjustment. The control group (n = 80) was based on the historical cohort of patients who received care before the CPE. Measure of clinical outcome applied in this study was number of lives saved/100 patients treated. Cost-effectiveness ratios for CKD stages 4 and 5 patients without CPE and with CPE and incremental cost-effectiveness ratios (ICERs) for CKD stages 4 and 5 patients were analyzed.

    RESULTS: Lives saved (%) in the treatment of CKD without CPE: CKD stage 4, 78.57; CKD stage 5, 57.58. Lives saved (%) in the treatment of CKD with CPE: CKD stage 4, 88.89; CKD stage 5, 65.45. Cost-effectiveness ratios for stage 4 with and without CPEs were Rp3,348,733.27 and Rp3,519,931.009, respectively. Cost-effectiveness ratios for stage 5 with and without CPEs were Rp7,137,874.93 and Rp7,871,822.27, respectively. ICERs were Rp2,045,341.22 for CKD stage 4 and Rp1,767,585.60 for CKD stage 5.

    CONCLUSIONS: Treatment of CKD stages 4 and 5 with CPE was more effective and cost-effective compared with treatment of CKD stages 4 and 5 without CPE. The ICERs indicated that extra costs were required to increase life saved in both stages.

    Matched MeSH terms: Cyclic N-Oxides
  8. Fulltext Free standing zirconia nanotubes formation and their photocatalytic properties
    Syahriza Ismail, Nurul Izza Soaid, Suriyati Mohamed Ansari, Nurulhuda Bashirom, Monna Rozana, Tan, Wai Kian, et al.
    Malaysian Journal of Microscopy, 2016;12(1):20-23.
    MyJurnal
    In the formation of ZrO2 (zirconia) nanotubes (ZNTs) by anodisation of zirconium, a balance between chemical etching at the surface of the nanotubes and inward growth inside the nanotubes is required. This can be achieved by using fluorinated organic electrolyte like ethylene glycol with the addition of small volume of oxidant. In this work, carbonate was selected as the oxidant and NH4F as the source of fluoride for chemical etching process. Two sets of electrolytes were studied EG/fluoride/Na2CO3 and EG/fluoride/K2CO3. It appears that in the presence of carbonate evolution of gas at the anode during the anodisation process was rather severe. The gas which is likely to be CO2 was found to weaken the adherence between the oxide film with the underlying Zr foil. This induced the formation of free standing ZNTs. High Resolution Transmission Electron Microscope (HRTEM) was used to investigate the crystallinity of the nanotubes where the majority crystal phase of ZNTs was tetragonal/cubic. The ZNTs were used as photocatalysts to oxidize methyl orange dye.
    Matched MeSH terms: Oxides
  9. Fulltext Graphene Oxide-Gold Nanosheets Containing Chitosan Scaffold Improves Ventricular Contractility and Function After Implantation into Infarcted Heart
    Saravanan S, Sareen N, Abu-El-Rub E, Ashour H, Sequiera GL, Ammar HI, et al.
    Sci Rep, 2018 10 10;8(1):15069.
    PMID: 30305684 DOI: 10.1038/s41598-018-33144-0
    Abnormal conduction and improper electrical impulse propagation are common in heart after myocardial infarction (MI). The scar tissue is non-conductive therefore the electrical communication between adjacent cardiomyocytes is disrupted. In the current study, we synthesized and characterized a conductive biodegradable scaffold by incorporating graphene oxide gold nanosheets (GO-Au) into a clinically approved natural polymer chitosan (CS). Inclusion of GO-Au nanosheets in CS scaffold displayed two fold increase in electrical conductivity. The scaffold exhibited excellent porous architecture with desired swelling and controlled degradation properties. It also supported cell attachment and growth with no signs of discrete cytotoxicity. In a rat model of MI, in vivo as well as in isolated heart, the scaffold after 5 weeks of implantation showed a significant improvement in QRS interval which was associated with enhanced conduction velocity and contractility in the infarct zone by increasing connexin 43 levels. These results corroborate that implantation of novel conductive polymeric scaffold in the infarcted heart improved the cardiac contractility and restored ventricular function. Therefore, our approach may be useful in planning future strategies to construct clinically relevant conductive polymer patches for cardiac patients with conduction defects.
    Matched MeSH terms: Oxides
  10. Fulltext Molecular dynamics simulations of sodium alginate/sulfonated graphene oxide membranes properties
    Shaari N, Kamarudin SK, Basri S
    Heliyon, 2018 Sep;4(9):e00808.
    PMID: 30246163 DOI: 10.1016/j.heliyon.2018.e00808
    The influence of methanol as a solvent on the properties of sodium alginate/sulfonated graphene oxide (SA/SGO) membranes was explored in water-methanol mixed conditions with various methanol concentrations and temperatures through molecular dynamics simulations. The methanol uptake of the membrane showed an isolation phase determined from the simulation results. The distance between the sulfonic acid groups increased in higher methanol concentrations, as observed from S-S RDFs. Furthermore, the distance between the SA-chain RDFs and the solvent molecules was analysed to determine a) the affinity of water towards the sulfonic acid groups and b) the affinity of the aromatic backbone of the SA towards methanol molecules. A decrease in water molecule diffusion led to an increase in methanol diffusion and uptake. SA/SGO membranes exhibited a smaller diffusion coefficient than that for the Nafion membranes, as calculated from simulation results and compared to the experimental work. Additionally, the diffusion ability increased at higher temperatures for all permeants. The interaction information obtained is useful for DMFC applications.
    Matched MeSH terms: Oxides
  11. Fulltext Preparation and characterization of yttrium barium copper oxide (YBCO) superconductor with addition of cobalt oxide (Co3O4)
    Jannah, A.N., Erwana, N.Y., Jamion, N.A.
    Journal of Academia Universiti Teknologi MARA Negeri Sembilan, 2018;6(1):31-38.
    MyJurnal
    This study was carried out to investigate the electrical properties of YBCO sample as superconductor
    and the effect of addition of Co3O4 on the superconducting properties of YBCO superconductor. The
    YBCO sample was prepared by solid state reaction route. The samples were prepared by each with
    weight percentage of cobalt oxide of x= 0.00, x= 0.01, x= 0.02 and x= 0.03. Electrical Conduction by
    Multimeter, Fourier Transform Infrared (FTIR), Critical temperature (Tc) measurement, X-ray
    Diffraction (XRD), and Scanning Electron Microscopy (SEM) were conducted for analysis.
    Multimeter showed all samples were in electric conduction, FTIR showed that carbonyl compound in
    the sample was removed after calcinations. Tc measurement showed that the critical temperature of
    sample of x= 0.02 was increased compared to sample of x= 0.00. XRD showed all samples have
    orthorhombic structure and SEM showed that the grain size was increased as increased the cobalt
    addition in YBCO superconductor. Besides, the EDX also showed the composition of elements
    YBCO were tally with chemicals used for pure YBCO and addition cobalt oxide into YBCO
    superconductor.
    Matched MeSH terms: Oxides
  12. Light transmission and internal scattering in pulsed laser-etched partially-transparent silicon wafers
    Rohaizar MH, Sepeai S, Surhada N, Ludin NA, Ibrahim MA, Sopian K, et al.
    Heliyon, 2019 Nov;5(11):e02790.
    PMID: 31768436 DOI: 10.1016/j.heliyon.2019.e02790
    Continuing trend in silicon wafer thickness directed at cost reduction approaches basic boundaries created by: (a) mismatch between Al paste and Si wafer thermal expansion and (b) incomplete optical absorption. With its symmetrical front and back electrical contacts, the bifacial solar cell setup reduces stress due to mismatch thermal expansion, decreases metal use and increases high temperature efficiency. Efficiency improvement is accomplished in bifacial solar cells by capturing light from the back surface. Partially transparent wafers provide an option to improve near-infrared radiation absorption within Si wafer. To fully absorb optical radiation, three-dimensional texture of these kinds of wafers is essential. Pulsed laser interactions, thermal oxidation, and wet chemical etching are included in this research. A feature of its energy and pattern setup is the interaction of pulsed laser with Si, running at 1.064 μm wavelength and micro-second length. Two experimental settings were explored: (a) post-laser chemical etching with potassium hydro-oxide etching with thermal oxide as etching mask and (b) post-laser heat Si surface oxidation. Due to fast melting and recrystallization, laser pulsed processing inherently produces its own texture. Some of these spherically-shaped, randomly focused characteristics improve inner scattering and boost near-infrared absorption within the wafer. These characteristics are separated during chemical etching with the thermally-grown oxide layer as an etch mask. Comparison of optical absorption in both surfaces shows almost a rise in the magnitude of absorption in non-etched surfaces. Detailed optical (optical microscope and IR absorption), morphological (field emission scanning electron microscope) and heat imaging (far IR camera) analyses were performed to comprehend physical processes that contribute to near-IR absorption improvement. Such kinds of partially-transparent, three-dimensional textured Si wafers are anticipated to discover applications for bifacial solar cells as substrates.
    Matched MeSH terms: Oxides
  13. New effective 3-aminopropyltrimethoxysilane functionalized magnetic sporopollenin-based silica coated graphene oxide adsorbent for removal of Pb(II) from aqueous environment
    Hassan AM, Wan Ibrahim WA, Bakar MB, Sanagi MM, Sutirman ZA, Nodeh HR, et al.
    J Environ Manage, 2020 Jan 01;253:109658.
    PMID: 31666209 DOI: 10.1016/j.jenvman.2019.109658
    A new effective adsorbent, 3-aminopropyltrimethoxysilane functionalized magnetic sporopollenin (MSp@SiO2NH2) based silica-coated graphene oxide (GO), (GO@SiO2-MSp@SiO2NH2) was successfully synthesized and applied for the first time in the removal of hazardous Pb(II) ions from aqueous solution. The properties of the composite were characterized using Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX) and vibrating-sample magnetometery (VSM). Evaluation of GO@SiO2-MSp@SiO2NH2 adsorption performance at optimum conditions revealed that the adsorbent has a maximum adsorption capacity of 323.5 mg/g for Pb(II) using 50-200 mg/L initial Pb(II) ions concentrations. Initial and final concentrations of Pb(II) ions in aqueous solution were analyzed using graphite furnace atomic absorption spectroscopy (GF-ASS). The adsorption behavior of Pb(II) ions onto GO@SiO2-MSp@SiO2NH2 was studied using Langmuir, Freundlich and Temkin isotherms models. The values of coefficient of determination showed that the adsorption best fitted the Langmuir model (R2 = 0.9994). Kinetic studies suggested that the adsorption of Pb(II) ion followed a pseudo-second-order rate model (R2 = 1.00) and thermodynamic studies revealed that the adsorption process is endothermic and spontaneous. The effect of co-existing ions on Pb(II) ion adsorption were also studied and found to have considerable effects only at higher matrix concentration. The adsorbent can be reused up to ten times and retain its good adsorption capacity. In addition, GO@SiO2-MSp@SiO2NH2 showed great potential for Pb(II)removal from industrial wastewater samples.
    Matched MeSH terms: Oxides
  14. Facile sonochemical synthesis of Ag2O-guar gum nanocomposite as a visible light photocatalyst for the organic transformation reactions
    Balachandramohan J, Sivasankar T, Sivakumar M
    J Hazard Mater, 2020 03 05;385:121621.
    PMID: 31784127 DOI: 10.1016/j.jhazmat.2019.121621
    Silver Oxide (Ag2O)-Guar gum nanocomposite was fabricated via a simple sonochemical co-precipitation method. The obtained photocatalyst was characterized with various techniques such as X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, UV-vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, scanning electron microscopy and transmission electron microscopy along with energy dispersion X-ray spectroscopy. The findings have demonstrated that Ag2O nanoparticles are spherical of 5-20 nm and were dispersed on the surface of polysaccharide guar gum to form Ag2O-guar gum nanocomposite. The as-synthesized nanocomposite was enacted as a competent photocatalyst for the reduction of nitrobenzene and oxidation of benzyl alchohol. The conversion efficiency for the reduction of nitrobenzene was 96 % with the addition of sodium borohydride, and the conversion of benzyl alcohol was 98 %. The highly efficient photocatalytic activity was due to the exceedingly dispersed Ag2O-guar gum nanocomposite where effective separation rate of energy driven electron-hole pairs and stronger light absorption occurs. The possible mechanism of the reactions was implicated in understanding the active species involved in the photocatalytic study.
    Matched MeSH terms: Oxides
  15. Surface morphology studies of low carbon steel treated in aqueous lignin
    YAHYA S, OTHMAN N, DAUD A, JALAR A
    Sains Malaysiana, 2013;42:1793-1798.
    The effect of corrosion inhibition of low carbon steel in water based medium containing lignin was investigated via weight loss method. The evolution of surface morphology has been carried out for 7 to 42 days via optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron microscopy (XPS). Immersion of metal specimen without lignin shows that significant increase in the surface roughness. The longer the immersion time, the more the oxide crust formed. The surface degradation of metal specimen was well protected by immersion in lignin solution. A protective layer containing of lignin was formed on the surface of metal specimens after 7 and 21 days immersion. The corrosion inhibition gives about 13 and 53% inhibition for both 7 and 21 days immersion, respectively. The protective layers were spalling and separated from the metal surface after 42 days immersion in lignin solution possibly due to the increase in corrosion attack after long time immersion according to the increase in dissolved oxygen and may also due to the thermal mismatch between oxide and substrate. The adsorption of protective layer containing lignin was temporary adsorbed on the surface.
    Matched MeSH terms: Oxides
  16. Effect of high temperature corrosion on austenitic stainless steel grade 304 in CO2 Gas at 700oC
    Nurul Atikah Shariff, Azman Jalar, Muhamad Izhar Sahri, Norinsan Kamil Othman
    Sains Malaysiana, 2014;43:1069-1075.
    Austenitic stainless steels of grade 304 were exposed to dry (Ar-75%CO2) and wet (Ar-75%CO2-12%H2O) environments at 700oC. This experimental setup involved horizontal tube furnace connected to CO2 gas and water vapour facilities. X-ray diffraction (XRD) technique, variable pressure-scanning electron microscope (VP-SEM) and optical microscope techniques were used to characterize the products of corrosion. The results of XRD showed that the phase of oxide layers consists of Cr2O3 and NiCr2O4 in dry CO2, meanwhile Fe2O3, Cr2O3, Fe0.56Ni0.34, Fe3O4 were identified in wet condition after 50 h. Adding 12%H2O in Ar-75%CO2 leads significantly in weight change occurred at 10 h exposure. However, after 20 h, the weight gain was decreased due to spallation of the oxide scale. The addition of water vapour accelerates the oxidation rate on the steel than that in dry condition. Morphologies and growth kinetics of these oxides vary with reaction condition. The oxidation behaviour at different times of exposure and the effect of water vapour were discussed in correlation with the microstructure of the oxides.
    Matched MeSH terms: Oxides
  17. Tribological behaviour of OA-capped WO3 nanoparticles as an additive to base oils
    Siti Fazlili Abdullah, Shahidan Radiman, Muhammad Azmi Abdul Hamid, Noor Baa’yah Ibrahim
    Sains Malaysiana, 2008;37:233-237.
    Oleic acid (OA) capped wolfram (VI) oxide, WO3 nanoparticles were chemically synthesized and characterized by means of Fourier Transform-Infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). The tribological properties of the capped WO3 nanoparticles as an additive in base oils were investigated using a four-ball machine. Results show that OA-capped WO3 nanoparticles are able to prevent water adsorption and capable of being dispersed stable in organic solvents which is base oils. The as-prepared capped WO3 nanoparticles have an average size of 15 nm. In addition, OA-capped WO3 nanoparticles as an additive in base oils perform good anti-wear (AW) and anti-friction (AF) properties owing to the formation of a boundary film.
    Matched MeSH terms: Oxides
  18. Evaluation on the Photocatalytic Degradation Activity of Reactive Blue 4 using Pure Anatase Nano-TiO2
    Joon Ching Juan, Sze Nee Goh, Ta Yeong Wu, Emy Marlina Samsudin, Tan Tong Ling, Sharifah Bee Abd. Hamid
    Sains Malaysiana, 2015;44:1011-1019.
    Disposal of dye wastewater into water streams without treatment endangers human and marine lives. This work focused on the second largest class of textile dyes after azo dyes due to its high resistivity to biodegradation and high toxicity. The photocatalytic degradation of Reactive Blue 4 (RB4), an anthraquinone dye, has been investigated using pure anatase nano titanium (IV) oxide (TiO2). The dye molecules were fully degraded and the addition of hydrogen peroxide (H2O2) enhanced the photodegradation efficiency. It is found that the degradation as the hydroxyl radicals in the bulk solution is sufficient for complete mineralisation. The disappearance of the dye follows pseudo-first-order kinetics. The effect of pH, amount of photocatalyst, UV-light intensity, light source and concentration of hydrogen peroxide was ascertained.
    Matched MeSH terms: Oxides
  19. Chemical synthesis of metal nanoparticles in aqueous solutions with the presence of some additives
    Oyama M, Akrajasali Umar, Muhammad M Atsalleh, Burhanuddin Eopmajlis
    Sains Malaysiana, 2011;40:1345-1353.
    Metal nanoparticles having interesting shapes can be prepared in aqueous solutions through simple reductions of metal ions with the presence of some additive reagents, such as cetyltrimethylammonium bromide and hexamethylenetetramine. In this review, some successful results for shape-controlled synthesis of metal nanoparticles in our group are summarized, which includes the synthesis of palladium nanocubes, palladium nanobricks, gold nanotripods. In addition, combining with indium tin oxide electrode surfaces, shape-controlled growth is shown to be possible to form gold nanoplates and copper oxide nanowires. Even in relatively mild synthetic conditions, interesting shape-controlled synthesis of metal nanoparticles is possible.
    Matched MeSH terms: Oxides
  20. Geochemical fractionation of hazardous elements in fresh and drilled weathered South African coal fly ashes
    Akinyemi SA, Gitari WM, Thobakgale R, Petrik LF, Nyakuma BB, Hower JC, et al.
    Environ Geochem Health, 2020 Sep;42(9):2771-2788.
    PMID: 31900823 DOI: 10.1007/s10653-019-00511-3
    The chemical reactions of dry-disposed ash dump, ingressed oxygen, carbon dioxide, and infiltrating rainwater affect mineralogical transformation, redistribution, and migration of chemical species. Composite samples of weathered coal fly ash taken at various depths and fresh coal fly ash were examined using organic petrographic, X-ray diffraction, X-ray fluorescence techniques, and successive extraction procedures. Results obtained show relative enrichment of glass, Al-Fe-oxides, calcite, and tridymite in the weathered CFA, but the fresh CFA is enriched in mullite, inertinite, maghemite, and ettringite. The enrichment of the weathered CFA in amorphous glass suggests higher reactivity when compared to fresh CFA. The evident depletion of soluble oxides in the weathered CFA is attributed to flushing of the soluble salts by percolating rainwater. Comparative enrichment of examined elements in water-soluble, exchangeable, reducible, and residual fractions of the weathered CFA is partly due to the slow release of adsorbed chemical species from the alumina-silicate matrix and diffusion from the deeper sections of the particles of coal fly ash. Sodium and potassium show enrichment in the oxidisable fraction of fresh CFA. The estimated mobility factor indicates mobility for Ca, Mg, Na, Se, Mo, and Sb and K, Sr, V, Cu, Cr, Se, and B in fresh and weathered CFAs, respectively.
    Matched MeSH terms: Oxides
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