MyMedR

Displaying publications 221 - 240 of 523 in total

Abstract:

Sort:

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: Oxidation-Reduction
Nano Fe304-activated carbon composites for aqueous supercapacitors

Ho M, Khiew P, Isa D, Tan T, Chiu W, Chia C, et al.

Sains Malaysiana, 2014;43:885-894.

In this study, a symmetric supercapacitor has been fabricated by adopting the nanostructured iron oxide (Fe304)-activated carbon (Ac) composite as the core electrode materials. The composite electrodes were prepared via a facile mechanical mixing process and PTFE polymeric solution has been used as the electrode material binder. Structural analysis of the nanocomposite electrodes were characterized by scanning electron microscopy ( sEm) and Brunauer-Emmett-Teller (BET) analysis. The electrochemical performances of the prepared supercapacitor were studied using cyclic voltammetry (cv) and electrochemical impedance spectroscopy (Eis) in 1.0 M Na2S03 and 1.0 M Na2SO4 aqueous solutions, respectively. The experimental results showed that the highest specific capacitance of 43 FIg is achieved with a fairly low Fe304 nanomaterials loading (4 wt. %) in 1 M Na2S03. It is clear that the low concentration of nanostructured Fe304 has improved the capacitive performance of the composite via pseudocapacitance charge storage mechanism as well as the enhancement on the specific surface areas of the electrode. However, further increasing of the Fe304 content in the electrode is found to distort the capacitive performance and deteriorate the specific surface area of the electrode, mainly due to the aggregation of the Fe304 particles within the composite. Additionally, the cv results showed that the Fe3041Ac nanocomposite electrode in Na2S03 electrolyte exhibits a better charge storage performance if compared with Na2SO4 solution. It is believed that Fe304 nanoparticles can provide favourable surface adsorption sites for sulphite (S032-) anions which act as catalysts for subsequent redox and intercalation reactions.

Matched MeSH terms: Oxidation-Reduction
Impact of pandan leaf etract addition on the oxidative degradation of sunflower oil during microwave heating

M. Abbas Ali, Rafiqqah binti Mohamad Sabri, Khu Say Li, Nik Azmi Nik Mahmood

Sains Malaysiana, 2015;44:1159-1166.

The efficacy of pandan leaf extract (PLE) addition on the oxidative degradation of sunflower oil (SFO) during microwave heating was studied. 80% of methanol extract showed better antioxidant action than the 100% methanol or ethanol extract and the total phenolic contents, DPPH radical scavenging activity and linoleic acid system of PLE were found to be 1845.50 mg GAE/100 g, 60.62-89.87% and 82.21%, respectively. 80% of methanolic extracts at different concentrations (0.1, 0.2 and 0.4 wt. %) were added to SFO. The antioxidant treated and control oil samples were subjected to microwave heating and were analyzed at regular intervals for the extent of oxidative changes following the measurements of peroxide value, p-anisidine value, TOTOX, free fatty acid, specific extinction, iodine value, viscosity, polar compounds and fatty acid composition. The PLE were found to be quite effective towards suppressing the primary and secondary oxidation products in the tested oil. The order of effectiveness (p<0.05) was BHA > 0.4% PLE > 0.2% PLE > 0.1% PLE > control. The present results suggested that antioxidant extract from pandan leaf might be used to protect vegetable oils from oxidation.

Matched MeSH terms: Oxidation-Reduction
A novel ruthenium-tungsten bimetallic complex dye-sensitizer for photoelectrochemical cells application

Khuzaimah Arifin, Wan Ramli Wan Daud, Mohammad B. Kassim

Sains Malaysiana, 2014;43:95-101.

A novel bimetallic double thiocyanate-bridged ruthenium and tungsten metal complex containing bipyridyl and dithiolene co-ligands was synthesized and the behavior of the complex as a dye-sensitizer for a photoelectrochemical (PEG) cell for a direct water splitting reaction was investigated. The ligands and metal complexes were characterized on the basis of elemental analysis as well as uv-Vis, Fourier transform infrared ( Pim) and nuclear magnetic resonance (11I and 13C NMR) spectroscopy. Cyclic voltammetry of the bimetallic complex showed multiple redox couples, in which half potentials E 112 at 0 .625 , 0.05 and 0.61 V were assigned as the formal redox processes of Ru(III)IRu(II) reduction, W(IV)IW(V) and W(V)IW(VI) oxidations, respectively. Photocurrent measurements were performed in homogeneous system and TiO2 was used as the photoanode for photocurrent measurements. Current density generated by the bimetallic complex was higher than that of N3 commercial dye which suggested that the bimetallic complex donated more electrons to the semiconductor.

Matched MeSH terms: Oxidation-Reduction
Potential toxic effects of chlorination and UV/chlorination in the treatment of hydrochlorothiazide in the water

Mansor NA, Tay KS

Sci Total Environ, 2020 Apr 20;714:136745.
PMID: 31982754 DOI: 10.1016/j.scitotenv.2020.136745

Chlorination is a common disinfection method in water treatment. This method can be converted into an advanced oxidation process by incorporating UV irradiation during water treatment. This study investigated the degradation of hydrochlorothiazide (HCTZ) by chlorination and UV/chlorination in water. HCTZ is a diuretic medication that has been frequently detected in wastewater. For chlorination, the second-order rate constant for the reaction between HCTZ with free available chlorine was found to increase with increasing pH from 5 to 8 due to the increase of the anionic HCTZ fraction. UV/chlorination was found to be more efficient in removing HCTZ as compared with chlorination due to the presence of reactive radical species such as hydroxyl radicals. For transformation by-products, chlorination was found to produce two by-products via chlorination and hydroxylation reactions that occurred at the aromatic ring of HCTZ. For UV/chlorination, an additional by-product formed through a radical reaction at the heterocyclic moiety of HCTZ was detected. Based on the Escherichia coli inhibition study, chlorination and UV/chlorination were found to increase the toxicity of the HCTZ solution. This result indicated that even UV/chlorination showed higher effectiveness in removing HCTZ; however, it also has the potential to generate toxic by-products and effluent.

Matched MeSH terms: Oxidation-Reduction
The relationship between heavy metals and trophic properties in Sembrong Lake, Johor

Nor Bakhiah Baharim, Ismail Yusoff, Wan Zakaria Wan Muhd Tahir, Muhamad Askari, Zainudin Othman, Mohamed Roseli Zainal Abidin, et al.

Sains Malaysiana, 2016;45:43-53.

The relationship between heavy metal and trophic properties in polymictic lake at Sembrong Lake, Peninsular Malaysia was assessed. Sixteen parameters, including heavy metals and trophic parameters were monitored. pH, temperature, dissolved oxygen and heavy metals level changes significantly influenced by the dynamic of polymictic mixing pattern. The mean concentrations of heavy metals in the reservoir decreased in the following order: Fe > Mn > Zn > Cu > As > Pb. The result showed that this polymictic lake is being threatened by cultural eutrophication with TSI value range from 72.40 to 80.41 and classified as a hypereutrophic lake. The levels of heavy metal pollution in the reservoir range from slightly polluted to polluted. Factor analysis was performed to determine the relationship between heavy metals and trophic parameters. Five factors were responsible for data structure and explained the 83% of total variance. These factors differentiate each group of parameters according to their common characteristics. Photosynthesis, respiration and redox processes were main factors contributing to the variability of both properties.

Matched MeSH terms: Oxidation-Reduction
Effect of rice bran oil addition on the oxidative degradation and fatty acid composition of soybean oil during heating

Ali MA, Islam MA, Othman NH, Noor AM, Ibrahim M

Acta Sci Pol Technol Aliment, 2020 1 14;18(4):427-438.
PMID: 31930793 DOI: 10.17306/J.AFS.0694

BACKGROUND: Rice bran oil (RBO) contains significant amounts of micronutrients (oryzanol, tocotrienol, tocopherol, phytosterols etc.) that impart a high resistance to thermal oxidation of the oil. The high oxidative stability of RBO can make it a preferred oil to improve the oxidative and flavor stabilities of other oils rich in PUFAs. In this study, the changes in the oxidative status and fatty acid composition in soybean oil (SO) blended with RBO under extreme thermal conditions were evaluated.
METHODS: The blends were prepared in a volume ratio of 10:90, 20:80, 40:60, and 60:40 (RBO:SO). The changes in the oxidative parameters and fatty acid composition of the samples during heating at frying temperature (170°C) were determined using analytical and instrumental methods. Oxidative alteration was also monitored by recording FTIR spectra of oil samples.
RESULTS: The increase in oxidative parameters (free fatty acid, color, specific extinctions, peroxide value, p-anisidine value, and thiobarbituric acid value) was greater in pure SO as compared to RBO or blend oils during heating. This indicates that the SO samples incorporated with RBO have the least degradation, while pure SO has the highest. Blending resulted in a lower level of polyunsaturated fatty acids (PUFA) with a higher level of saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA). During heating, the relative content of PUFA decreased and that of SFA increased. However, the presence of RBO in SO slowed down the oxidative deterioration of PUFA. In FTIR, the peak intensities in SO were markedly changed in comparison with blend oils during heating. The reduction in the formation of oxidative products in SO during thermal treatment increased as the concentration of the RBO in SO increased; however, the levels of the protective effect of RBO did not increase steadily with an increase in its concentration.
CONCLUSIONS: During thermal treatment, the generation of hydroperoxides, their degradation and formation of secondary oxidative products as evaluated by oxidative indices, fatty acids and IR absorbances were lower in blend oils compared to pure SO. In conclusion, RBO can significantly retard the process of lipid peroxidation in SO during heating at frying temperature.

Matched MeSH terms: Oxidation-Reduction
Fulltext Proteomics analysis on lipid metabolism in Elaeis guineensis and Elaeis oleifera

Lau BYC, Amiruddin MD, Othman A

Data Brief, 2020 Aug;31:105714.
PMID: 32462070 DOI: 10.1016/j.dib.2020.105714

Proteome data was obtained from the fruit mesocarps of the two oil palm species, namely, the African Elaeis guineensis (commercial tenera or commonly known as D x P and MPOB-Nigerian tenera) and the South American Elaeis oleifera. Total proteins were extracted from randomly selected fruitlets and subjected to proteomics characterisation by means of liquid chromatography mass spectrometry. Number of proteins identified, the grouping of the biological replicates from five developmental weeks after anthesis, and the localisation of gene corresponded to the detected proteins on the oil palm chromosomes, were presented. A total of 4,116, 4,210 and 4,081 proteins were found in commercial tenera and MPOB Nigerian tenera for Elaeis guineensis; and Elaeis oleifera, respectively. Principal component analysis showed two distinct clusters that corresponded to Elaeis guineensis and Elaeis oleifera. Collectively, genes that corresponded to the identified proteins were found to be located in all 16 oil palm chromosomes. A total of 59 proteins from Elaeis guineensis and Elaeis oleifera were down-regulated for >5-fold change during the peak of lipid biosynthesis compared to the onset. The same comparative analysis revealed that 66 proteins were up-regulated for >5-fold change. About 60.0% of the observed proteins were involved in catalytic activity while 28.5% were associated with redox reaction. Based on same datasets, the tricarboxylic acid cycle and 5-hydroxytryptamine degradation pathways were found to be enriched the most (>36-fold change). These data can be used to support the oil palm gene model validation and lipid metabolism research, particularly in the areas of oil yield and quality. The tabulated protein lists of identified proteins and their expression changes from these varieties were provided as supplementary files. Raw MSF and mzid files for all the oil palm species were deposited in the ProteomeXchange (PXD017436).

Matched MeSH terms: Oxidation-Reduction
Fulltext Synergetic Effects of Hybrid Carbon Nanostructured Counter Electrodes for Dye-Sensitized Solar Cells: A Review

Samantaray MR, Mondal AK, Murugadoss G, Pitchaimuthu S, Das S, Bahru R, et al.

Materials (Basel), 2020 Jun 19;13(12).
PMID: 32575516 DOI: 10.3390/ma13122779

This article provides an overview of the structural and physicochemical properties of stable carbon-based nanomaterials and their applications as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). The research community has long sought to harvest highly efficient third-generation DSSCs by developing carbon-based CEs, which are among the most important components of DSSCs. Since the initial introduction of DSSCs, Pt-based electrodes have been commonly used as CEs owing to their high-electrocatalytic activities, thus, accelerating the redox couple at the electrode/electrolyte interface to complete the circuit. However, Pt-based electrodes have several limitations due to their cost, abundance, complicated facility, and low corrosion resistance in a liquid electrolyte, which further restricts the large-area applications of DSSCs. Although carbon-based nanostructures showed the best potential to replace Pt-CE of DSSC, several new properties and characteristics of carbon-CE have been reported for future enhancements in this field. In this review, we discuss the detailed synthesis, properties, and performances of various carbonaceous materials proposed for DSSC-CE. These nano-carbon materials include carbon nanoparticles, activated carbon, carbon nanofibers, carbon nanotube, two-dimensional graphene, and hybrid carbon material composites. Among the CE materials currently available, carbon-carbon hybridized electrodes show the best performance efficiency (up to 10.05%) with a high fill factor (83%). Indeed, up to 8.23% improvements in cell efficiency may be achieved by a carbon-metal hybrid material under sun condition. This review then provides guidance on how to choose appropriate carbon nanomaterials to improve the performance of CEs used in DSSCs.

Matched MeSH terms: Oxidation-Reduction
Facile production of nanostructured cellulose from Elaeis guineensis empty fruit bunch via one pot oxidative-hydrolysis isolation approach

Chen YW, Lee HV, Abd Hamid SB

Carbohydr Polym, 2017 Feb 10;157:1511-1524.
PMID: 27987863 DOI: 10.1016/j.carbpol.2016.11.030

Cellulose in nanostructures was successfully isolated from empty fruit bunch biomass via a novel one-pot oxidative-hydrolysis technique. The physicochemical properties of nanocellulose prepared via one-pot process have shown comparable characteristics as products isolated via conventional multistep purification approach (namely dewaxing, chlorite bleaching process, alkalization, and acid hydrolysis). The chemical composition study indicated that the one-pot oxidative-hydrolysis process successfully extracted cellulose (91.0%), with the remaining minority being hemicellulose and lignin (∼6%) in the final product. Crystallinity profile of one-pot treated product (80.3%) was higher than that of multistep isolated nanocellulose (75.4%), which indicated that the disorder region (amorphous) in cellulose fibers was successfully removed. In additional to that, the morphology study demonstrated that nanocellulose prepared by one-pot process rendered spider-web-like network nanostructure, with an average diameter of fibers at a range of 51.6±15.4nm. The nanocellulose product showed high thermal stability (320°C), which was ready for nanocomposite application. One-pot oxidative-hydrolysis technique is a simple and versatile route for the preparation of nanocellulose from complex biomass within 90°C and 6h period, with minimum wastewater as compared to the multistep process.

Matched MeSH terms: Oxidation-Reduction
Stabilized landfill leachate treatment by coagulation-flocculation coupled with UV-based sulfate radical oxidation process

Ishak AR, Hamid FS, Mohamad S, Tay KS

Waste Manag, 2018 Jun;76:575-581.
PMID: 29503052 DOI: 10.1016/j.wasman.2018.02.047

In this work, the feasibility of coagulation-flocculation coupled with UV-based sulfate radical oxidation process (UV/SRAOP) in the removal of chemical oxygen demand (COD) of stabilized landfill leachate (SLL) was evaluated. For coagulation-flocculation, ferric chloride (FeCl3) was used as the coagulant. The effect of initial pH of SLL and COD:FeCl3 ratio on the COD removal was evaluated. The result revealed that COD:FeCl3 ratio of 1:1.3 effectively removed 76.9% of COD at pH 6. The pre-treated SLL was then subjected to UV/SRAOP treatment. For UV/SRAOP, the sulfate radical (SR) was generated using UV-activated persulfate (UV/PS) and peroxymonosulfate (UV/PMS). The dosage of oxidant and reaction time were found to be the main parameters that influence the efficiency of COD removal. On the other hand, the effect of initial pH (3-7) and the type of oxidant (PS and PMS) was found to have no significant influence on COD removal efficiency. At optimum conditions, approximately 90.9 and 91.5% of COD was successfully removed by coagulation-flocculation coupled with UV/PS and UV/PMS system, respectively. Ecotoxicity study using zebrafish showed a reduction in toxicity of SLL from 10.1 to 1.74 toxicity unit (TU) after coagulation-flocculation. The TU remained unchanged after UV/PS treatment but slightly increased to 1.80 after UV/PMS treatment due to the presence of residual sulfate ion in the treated effluent. In general, it can be concluded that coagulation-flocculation coupled with UV/SRAOP could be a potential water treatment method for SLL treatment.

Matched MeSH terms: Oxidation-Reduction
The antioxidant effects of Cosmos caudatus and Polygonum minus in refrigerated duck meatballs

Nurul, H., Ruzita, A., Aronal, A.P.

International Food Research Journal, 2010;17(4):893-904.
MyJurnal

This study evaluated lipid oxidation in refrigerated (±4ºC) duck meatballs treated with novel antioxidants over 21 days of storage. The duck meatballs were treated with a control substance, Cosmos caudatus (ulam raja) or Polygonum minus (kesum) extract, or BHT (butylated hydroxytoluene), and data was collected every three days. These results showed that Cosmos caudatus and Polygonum minus had better antioxidant effects on duck meatballs than BHT or the control. Folding and microbial potency test results were not significantly different among the three antioxidants tested but were better in antioxidant-treated samples than in control samples. However, Cosmos caudatus and Polygonum minus were slightly more effective in preventing microbial growth. This result suggests that Cosmos caudatus and Polygonum minus may be potentially useful natural resources for enhancing the shelf life of duck meatballs.

Matched MeSH terms: Oxidation-Reduction
Fulltext Oxidative stability of sunflower oils supplemented with kenaf seeds extract, roselle seeds extract and roselle extract, respectively under accelerated storage

Nyam, K.L., Wong, M.M., Long, K., Tan, C.P.

International Food Research Journal, 2013;20(2):695-701.
MyJurnal

With the concern of adverse effects of lipid oxidation on food deterioration and human health, the antioxidant activities of kenaf seed extracts (KSE), roselle seed extracts (RSE) and roselle extracts (RE) were evaluated by comparing its oxidative stability in refined, bleached & deodorised (RBD) sunflower oils with that of in synthetic antioxidant, BHA. Established methods such as peroxide values (PV), p-anisidine values (AV), TOTOX values, free fatty acids (FFA), iodine values (IV), total phenolic contents (TPC), conjugated dienes (CD) and conjugated triene (CT) were employed to assess the extent of oil deterioration. During 24 days storage, consensus was accomplished based on the results assessed by PV, TOTOX, CD, CT, IV and TPC at which the antioxidant activities of KSE, RSE and RE were better than BHA. Surprisingly, the results obtained by AV and FFA assays showed the reversed. Among the extracts, RSE exhibited the best antioxidant activities. These suggest that KSE, RSE and RE may be used as potential source of natural antioxidants in the application of food industry to prevent lipid oxidation.

Matched MeSH terms: Oxidation-Reduction
Fulltext Response surface optimization of enzymatic hydrolysis conditions of lead tree (Leucaena leucocephala) seed hydrolysate

Rafi, N.M., Halim, N.R.A., Amin, A.M., Sarbon, N.M.

International Food Research Journal, 2015;22(3):1015-1023.
MyJurnal

The enzymatic hydrolysis of lead tree seed protein with alcalase to obtain Lead Tree Seed Hydrosylate (LTSH) was optimized using response surface methodology (RSM). A three- tiered, factor face centered, central composite design (CCD) was used to study the influence of four independent variables namely: pH (7–9); hydrolysis temperature (50oC, 55oC, 60oC); hydrolysis time (30 min, 60 min, 90 min); and enzyme/substrate (1%, 2%, 3%) ratio on both yield and antioxidant activity. The CCD consisted of twenty-four experimental points and six replicates of central points. All data were analyzed using Design-Expert Software. The optimum conditions obtained from experiments were a pH of 9; an enzyme to substrate ratio of 2%; a hydrolysis time of 90 min; and a temperature of 55°C. Results showed that LTSH derived from optimized hydrolysis exhibited effective ferrous ion chelating activity (92.79%) and strong reducing power (A700 = 3.82) at a concentration of 20 mg/ml. LTSH also demonstrated high DPPH radical scavenging activity (76.21%; IC50 1.99 mg/ml), as well as hydroxyl radical scavenging activity (66.72%; IC50 2.45 mg/ml). Superoxide anion scavenging activity was 55.71% (IC50 3.89 mg/ml) at 20 mg/ml. These results suggest that LTSH has potential as a natural antioxidant of functional food and for use in food processing.

Matched MeSH terms: Oxidation-Reduction
Potential of porous Co3O4 nanorods as cathode catalyst for oxygen reduction reaction in microbial fuel cells

Kumar R, Singh L, Zularisam AW, Hai FI

Bioresour Technol, 2016 Nov;220:537-542.
PMID: 27614156 DOI: 10.1016/j.biortech.2016.09.003

This study aims to investigate the potential of porous Co3O4 nanorods as the cathode catalyst for oxygen reduction reaction (ORR) in aqueous air cathode microbial fuel cells (MFCs). The porous Co3O4 nanorods were synthesized by a facile and cost-effective hydrothermal method. Three different concentrations (0.5mg/cm(2), 1mg/cm(2), and 2mg/cm(2)) of Co3O4 nanorods coated on graphite electrodes were used to test its performance in MFCs. The results showed that the addition of porous Co3O4 nanorods enhanced the electrocatalytic activity and ORR kinetics significantly and the overall resistance of the system was greatly reduced. Moreover, the MFC with a higher concentration of the catalyst achieved a maximum power density of 503±16mW/m(2), which was approximately five times higher than the bare graphite electrode. The improved catalytic activity of the cathodes could be due to the porous properties of Co3O4 nanorods that provided the higher number of active sites for oxygen.

Matched MeSH terms: Oxidation-Reduction
Fulltext Immunosuppressive Effects of Natural α,β-Unsaturated Carbonyl-Based Compounds, and Their Analogs and Derivatives, on Immune Cells: A Review

Arshad L, Jantan I, Bukhari SN, Haque MA

Front Pharmacol, 2017;8:22.
PMID: 28194110 DOI: 10.3389/fphar.2017.00022

The immune system is complex and pervasive as it functions to prevent or limit infections in the human body. In a healthy organism, the immune system and the redox balance of immune cells maintain homeostasis within the body. The failure to maintain the balance may lead to impaired immune response and either over activity or abnormally low activity of the immune cells resulting in autoimmune or immune deficiency diseases. Compounds containing α,β-unsaturated carbonyl-based moieties are often reactive. The reactivity of these groups is responsible for their diverse pharmacological activities, and the most important and widely studied include the natural compounds curcumin, chalcone, and zerumbone. Numerous studies have revealed the mainly immunosuppressive and anti-inflammatory activities of the aforesaid compounds. This review highlights the specific immunosuppressive effects of these natural α,β-unsaturated carbonyl-based compounds, and their analogs and derivatives on different types of immune cells of the innate (granulocytes, monocytes, macrophages, and dendritic cells) and adaptive (T cells, B cells, and natural killer cells) immune systems. The inhibitory effects of these compounds have been comprehensively studied on neutrophils, monocytes and macrophages but their effects on T cells, B cells, natural killer cells, and dendritic cells have not been well investigated. It is of paramount importance to continue generating experimental data on the mechanisms of action of α,β-unsaturated carbonyl-based compounds on immune cells to provide useful information for ensuing research to discover new immunomodulating agents.

Matched MeSH terms: Oxidation-Reduction
Anammox process for aquaculture wastewater treatment: operational condition, mechanism, and future prospective

Ismail IN, Taufik M, Umor NA, Norulhuda MR, Zulkarnaini Z, Ismail S

Water Sci Technol, 2022 Dec;86(12):3093-3112.
PMID: 36579872 DOI: 10.2166/wst.2022.403

Treatment of ammonia- and nitrate-rich wastewater, such as that generated in the aquaculture industry, is important to prevent environmental pollution. The anaerobic ammonium oxidation (anammox) process has been reported as a great alternative in reducing ammoniacal nitrogen concentration in aquaculture wastewater treatment compared to conventional treatment systems. This paper will highlight the impact of the anammox process on aquaculture wastewater, particularly in the regulation of ammonia and nitrogen compounds. The state of the art for anammox treatment systems is discussed in comparison to other available treatment methods. While the anammox process is viable for the treatment of aquaculture wastewater, the efficiency of nitrogen removal could be further improved through the proper use of anammox bacteria, operating conditions, and microbial diversity. In conclusion, a new model of the anammox process is proposed in this review.

Matched MeSH terms: Oxidation-Reduction
Hexavalent molybdenum reduction to Mo-blue by Acinetobacter calcoaceticus

Shukor MY, Rahman MF, Suhaili Z, Shamaan NA, Syed MA

Folia Microbiol (Praha), 2010 Mar;55(2):137-43.
PMID: 20490756 DOI: 10.1007/s12223-010-0021-x

A local molybdenum-reducing bacterium was isolated and tentatively identified as Acinetobacter calcoaceticus strain Dr.Y12 based on carbon utilization profiles using Biolog GN plates and 16S rDNA comparative analysis. Molybdate reduction was optimized under conditions of low dissolved oxygen (37 degrees C and pH 6.5). Of the electron donors tested, glucose, fructose, maltose and sucrose supported molybdate reduction after 1 d of incubation, glucose and fructose supporting the highest Mo-blue production. Optimum Mo-blue production was reached at 20 mmol/L molybdate and 5 mmol/L phosphate; increasing the phosphate concentrations inhibited the production. An increase in an overall absorption profiles, especially at peak maximum at 865 nm and the shoulder at 700 nm, was observed in direct correlation with the increased in Mo-blue amounts. Metal ions, such as chromium, cadmium, copper, mercury and lead (2 mmol/L final concentration) caused approximately 88, 53, 80, 100, and 20 % inhibition, respectively. Respiratory inhibitors, such as antimycin A, rotenone, sodium azide and cyanide showed in this bacterium no inhibition of the Mo-blue production, suggesting that the electron transport system is not a site of molybdate reduction.

Matched MeSH terms: Oxidation-Reduction
Degradation of levofloxacin from antibiotic wastewater by pulse electrochemical oxidation with BDD electrode

Xu T, Tang X, Qiu M, Lv X, Shi Y, Zhou Y, et al.

J Environ Manage, 2023 Oct 15;344:118718.
PMID: 37541001 DOI: 10.1016/j.jenvman.2023.118718

Antibiotic-containing wastewater is a typical biochemical refractory organic wastewater and general treatment methods cannot effectively and quickly degrade the antibiotic molecules. In this study, a novel boron-doped diamond (BDD) pulse electrochemical oxidation (PEO) technology was proposed for the efficient removal of levofloxacin (LFXN) from wastewater. The effects of current density (j), initial pH (pH0), frequency (f), electrolyte types and initial concentration (c0(LFXN)) on the degradation of LFXN were systematically investigated. The degradation kinetics under four different processes have also been studied. The possible degradation mechanism of LFXN was proposed by Density functional theory calculation and analysis of degradation intermediates. The results showed that under the optimal parameters, the COD removal efficiency (η(COD)) was 94.4% and the energy consumption (EEC) was 81.43 kWh·m-3 at t = 120 min. The degradation of LFXN at pH = 2.8/c(H2O2) followed pseudo-first-order kinetics. The apparent rate constant was 1.33 × 10-2 min-1, which was much higher than other processes. The degradation rate of LFXN was as follows: pH = 2.8/c(H2O2) > pH = 2.8 > pH = 7/c(H2O2) > pH = 7. Ten aromatic intermediates were formed during the degradation of LFXN, which were further degraded to F-, NH4+, NO3-, CO2 and H2O. This study provides a promising approach for efficiently treating LFXN antibiotic wastewater by pulsed electrochemical oxidation with a BDD electrode without adding H2O2.

Matched MeSH terms: Oxidation-Reduction
A method to study the effects of chemical and biological reduction of molybdate to molybdenum blue in bacteria

Shukor Y, Shamsuddin B, Mohamad O, Ithnin K

Pak J Biol Sci, 2008 Feb 15;11(4):672-5.
PMID: 18817148

In this research, we modify a previously developed assay for the quantification molybdenum blue to determine whether inhibitors to molybdate reduction in bacteria inhibits cellular reduction or inhibit the chemical formation of one of the intermediate of molybdenum blue; phosphomolybdate. We manage to prove that inhibition of molybdate reduction by phosphate and arsenate is at the level of phosphomolybdate and not cellular. We also prove that mercury is a physiological inhibitor to molybdate reduction. We suggest the use of this method to assess the effect of inhibitors and activators to molybdate reduction in bacteria.

Matched MeSH terms: Oxidation-Reduction

Filters

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links