MyMedR

Displaying publications 221 - 240 of 1088 in total

Abstract:

Sort:

Fulltext Multicentre study of preoxygenation practices by anaesthesia providers

Wong AK, Sushila S, Thomas H, Tong JMG

Med J Malaysia, 1999 Mar;54(1):102-9.
PMID: 10972012

A total of 155 consecutive anaesthetics in three public Malaysian hospitals were prospectively studied to assess preoxygenation practices by their anaesthesia providers. Preoxygenation was practised in 96.1% of patients. Specialist and non-specialist anaesthesiologist did not preoxygenate 8.8% and 2.3% of their patients, respectively. Overall incidence of arterial oxygen desaturation during induction was 15.5%. Arterial oxygen desaturation occurred more frequently with emergency surgery (30.2%) in comparison to elective surgery (9.8%). Arterial oxygen desaturation occurred more frequently with non-specialist (18.9%) than specialist anaesthesia providers (3.0%).

Matched MeSH terms: Oxygen/blood; Oxygen/therapeutic use*
Madecassoside activates anti‑neuroinflammatory mechanisms by inhibiting lipopolysaccharide‑induced microglial inflammation

Sasmita AO, Ling APK, Voon KGL, Koh RY, Wong YP

Int J Mol Med, 2018 May;41(5):3033-3040.
PMID: 29436598 DOI: 10.3892/ijmm.2018.3479

Neurodegeneration is typically preceded by neuroinflammation generated by the nervous system to protect itself from tissue damage, however, excess neuroinflammation may inadvertently cause more harm to the surrounding tissues. Attenuating neuroinflammation with non‑steroidal anti‑inflammatory drugs can inhibit neurodegeneration. However, such treatments induce chronic side effects, including stomach ulcers. Madecassoside, a triterpene derived from Centella asiatica, is considered to be an alternative treatment of inflammation. In the present study, the anti‑neuroinflammatory properties of madecassoside were assessed in BV2 microglia cells, which were pre‑treated with madecassoside at a maximum non‑toxic dose (MNTD) of 9.50 µg/ml and a ½ MNTD of 4.75 µg/ml for 3 h and stimulated with 0.1 µg/ml lipopolysaccharide (LPS). The effect of madecassoside was assessed by determining reactive oxygen species (ROS) levels in all groups. Furthermore, the expression of pro‑ and anti‑neuroinflammatory genes and proteins were analyzed using reverse transcription‑quantitative polymerase chain reaction and western blotting, respectively. The results demonstrated that ROS levels in cells treated with the MNTD of madecassoside were significantly reduced compared with cells treated with LPS alone (P<0.05). The expression of pro‑neuroinflammatory genes, including inducible nitric oxide synthase, cyclooxygenase‑2, signal transducer and activator of transcription 1 and nuclear factor‑κB, were significantly downregulated in a dose‑independent manner following treatment with madecassoside. Conversely, the anti‑neuroinflammatory component heme oxygenase 1 was significantly upregulated by 175.22% in the MNTD‑treated group, compared with cells treated with LPS alone (P<0.05). The gene expression profiles of pro‑ and anti‑inflammatory genes were also consistent with the results of western blotting. The results of the present study suggest that madecassoside may be a potent anti‑neuroinflammatory agent. The antioxidative properties of madecassoside, which serve a major role in anti‑neuroinflammation, indicate that this compound may be a functional natural anti‑neuroinflammatory agent, therefore, further in vivo or molecular studies are required.

Matched MeSH terms: Reactive Oxygen Species/analysis; Reactive Oxygen Species/immunology
Fulltext Performance of wild-Serbian Ganoderma lucidum mycelium in treating synthetic sewage loading using batch bioreactor

Mohd Hanafiah Z, Wan Mohtar WHM, Abu Hasan H, Jensen HS, Klaus A, Wan-Mohtar WAAQI

Sci Rep, 2019 11 06;9(1):16109.
PMID: 31695087 DOI: 10.1038/s41598-019-52493-y

The fluctuation of domestic wastewater characteristic inhibits the current conventional microbial-based treatment. The bioremediation fungi has received attention and reported to be an effective alternative to treat industrial wastewater. Similar efficient performance is envisaged for domestic wastewater whereby assessed performance of fungi for varying carbon-to-nitrogen ratios in domestic wastewater is crucial. Thus, the performance of pre-grown wild-Serbian Ganoderma lucidum mycelial pellets (GLMPs) was evaluated on four different synthetic domestic wastewaters under different conditions of initial pH (pH 4, 5, and 7) and chemical oxygen demand (COD) to nitrogen (COD/N) ratio of 3.6:1, 7.1:1, 14.2:1, and 17.8:1 (C3.6N1, C7.1N1, C14.2N1, and C17.8N1). The COD/N ratios with a constant concentration of ammonia-nitrogen (NH3-N) were chosen on the basis of the urban domestic wastewater characteristics sampled at the inlet basin of a sewage treatment plant (STP). The parameters of pH, COD, and NH3-N were measured periodically during the experiment. The wild-Serbian GLMPs efficiently removed the pollutants from the synthetic sewage. The COD/N ratio of C17.8N1 wastewater had the best COD and NH3-N removal, as compared to the lower COD/N ratio, and the shortest treatment time was obtained in an acidic environment at pH 4. The highest percentage for COD and NH3-N removal achieved was 96.0% and 93.2%, respectively. The results proved that the mycelium of GLMP has high potential in treating domestic wastewater, particularly at high organic content as a naturally sustainable bioremediation system.

Matched MeSH terms: Oxygen/analysis; Oxygen/metabolism
Fulltext Dengue Virus-Induced Reactive Oxygen Species Production in Rat Microglial Cells

Suwanprinya L, Morales NP, Sanvarinda P, Dieng H, Okabayashi T, Morales Vargas RE

Jpn J Infect Dis, 2017 07 24;70(4):383-387.
PMID: 28003593 DOI: 10.7883/yoken.JJID.2016.236

Encephalitis has been described worldwide as a severe complication in patients infected by dengue virus. Reactive oxygen species (ROS) production is a key mechanism involved in the neuronal damage caused by viral encephalitis. In the present study, the capability of dengue virus serotypes 2 (DENV2) and DENV4 to induce ROS production was investigated in a rat microglial cell line, HAPI cells. The cells were infected with DENV2 and DENV4 at a multiplicity of infection of 0.1 for a 2-h adsorption period. Japanese encephalitis virus (JEV) was used as the reference. DENV2- and DENV4-induced microglial activation and significantly increased ROS production corresponded to decreased cell viability. The activity of DENV4 was significantly higher than the activities of DENV2 and JEV at 48 and 72 h post infection. DENV4 partly induced ROS production via an iron-induced Fenton reaction, as demonstrated by the treatment with an iron chelator, deferiprone. Despite the induction of increased inducible nitric oxide synthase expression and nitric oxide (NO) production by JEV, DENV2, and DENV4 did not induce NO production, suggesting the activation of different pathways in response to infections by different viruses. In conclusion, DENV2 and DENV4 have the capability to induce ROS production and activate microglia, which have been reported as the key components of neuronal damage.

Matched MeSH terms: Reactive Oxygen Species/metabolism*; Reactive Oxygen Species/toxicity
Fulltext Targeted Oxygen in the Resuscitation of Preterm Infants, a Randomized Clinical Trial

Oei JL, Saugstad OD, Lui K, Wright IM, Smyth JP, Craven P, et al.

Pediatrics, 2017 01;139(1).
PMID: 28034908 DOI: 10.1542/peds.2016-1452

BACKGROUND AND OBJECTIVES: Lower concentrations of oxygen (O2) (≤30%) are recommended for preterm resuscitation to avoid oxidative injury and cerebral ischemia. Effects on long-term outcomes are uncertain. We aimed to determine the effects of using room air (RA) or 100% O2 on the combined risk of death and disability at 2 years in infants <32 weeks' gestation.
METHODS: A randomized, unmasked study designed to determine major disability and death at 2 years in infants <32 weeks' gestation after delivery room resuscitation was initiated with either RA or 100% O2 and which were adjusted to target pulse oximetry of 65% to 95% at 5 minutes and 85% to 95% until NICU admission.
RESULTS: Of 6291 eligible patients, 292 were recruited and 287 (mean gestation: 28.9 weeks) were included in the analysis (RA: n = 144; 100% O2: n = 143). Recruitment ceased in June 2014, per the recommendations of the Data and Safety Monitoring Committee owing to loss of equipoise for the use of 100% O2. In non-prespecified analyses, infants <28 weeks who received RA resuscitation had higher hospital mortality (RA: 10 of 46 [22%]; than those given 100% O2: 3 of 54 [6%]; risk ratio: 3.9 [95% confidence interval: 1.1-13.4]; P = .01). Respiratory failure was the most common cause of death (n = 13).
CONCLUSIONS: Using RA to initiate resuscitation was associated with an increased risk of death in infants <28 weeks' gestation. This study was not a prespecified analysis, and it was underpowered to address this post hoc hypothesis reliably. Additional data are needed.

Matched MeSH terms: Oxygen Inhalation Therapy/adverse effects; Oxygen Inhalation Therapy/methods*
River water quality assessment using environmentric techniques: case study of Jakara River Basin

Mustapha A, Aris AZ, Juahir H, Ramli MF, Kura NU

Environ Sci Pollut Res Int, 2013 Aug;20(8):5630-44.
PMID: 23443942 DOI: 10.1007/s11356-013-1542-z

Jakara River Basin has been extensively studied to assess the overall water quality and to identify the major variables responsible for water quality variations in the basin. A total of 27 sampling points were selected in the riverine network of the Upper Jakara River Basin. Water samples were collected in triplicate and analyzed for physicochemical variables. Pearson product-moment correlation analysis was conducted to evaluate the relationship of water quality parameters and revealed a significant relationship between salinity, conductivity with dissolved solids (DS) and 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), and nitrogen in form of ammonia (NH4). Partial correlation analysis (r p) results showed that there is a strong relationship between salinity and turbidity (r p=0.930, p=0.001) and BOD5 and COD (r p=0.839, p=0.001) controlling for the linear effects of conductivity and NH4, respectively. Principal component analysis and or factor analysis was used to investigate the origin of each water quality parameter in the Jakara Basin and identified three major factors explaining 68.11 % of the total variance in water quality. The major variations are related to anthropogenic activities (irrigation agricultural, construction activities, clearing of land, and domestic waste disposal) and natural processes (erosion of river bank and runoff). Discriminant analysis (DA) was applied on the dataset to maximize the similarities between group relative to within-group variance of the parameters. DA provided better results with great discriminatory ability using eight variables (DO, BOD5, COD, SS, NH4, conductivity, salinity, and DS) as the most statistically significantly responsible for surface water quality variation in the area. The present study, however, makes several noteworthy contributions to the existing knowledge on the spatial variations of surface water quality and is believed to serve as a baseline data for further studies. Future research should therefore concentrate on the investigation of temporal variations of water quality in the basin.

Matched MeSH terms: Oxygen/analysis; Biological Oxygen Demand Analysis
Effects of acute supplementation of caffeine on cardiorespiratory responses during endurance running in a hot & humid climate

Ping WC, Keong CC, Bandyopadhyay A

Indian J Med Res, 2010 Jul;132:36-41.
PMID: 20693587

Athletes in Malaysia need to perform in a hot and humid climate. Chronic supplementation of caffeine on endurance performance have been studied extensively in different populations. However, concurrent research on the effects of acute supplementation of caffeine on cardiorespiratory responses during endurance exercise in the Malaysian context especially in a hot and humid environment is unavailable.

Matched MeSH terms: Oxygen Consumption/drug effects*; Oxygen Consumption/physiology
Fulltext Graphene oxide electrocatalyst on MnO₂ air cathode as an efficient electron pump for enhanced oxygen reduction in alkaline solution

Basirun WJ, Sookhakian M, Baradaran S, Endut Z, Mahmoudian MR, Ebadi M, et al.

Sci Rep, 2015;5:9108.
PMID: 25765731 DOI: 10.1038/srep09108

Graphene oxide (GO) was deposited on the surface of a MnO2 air cathode by thermal evaporation at 50°C from a GO colloidal suspension. Fourier transformed infrared spectroscopy and field emission scanning electron microscopy confirmed the presence of GO on the MnO2 air cathode (GO-MnO2). Voltammetry and chrono-amperometry showed increased currents for the oxygen reduction reaction (ORR) in 6 M KOH solution for GO-MnO2 compared to the MnO2 cathode. The GO-MnO2 was used as an air cathode in an alkaline tin-air cell and produced a maximum power density of 13 mW cm(-2), in contrast to MnO2, which produced a maximum power density of 9.2 mW cm(-2). The electrochemical impedance spectroscopy results suggest that the chemical step for the ORR is the rate determining step, as proposed earlier by different researchers. It is suggested that the presence of GO and electrochemically reduced graphene oxide (ERGO) on the MnO2 surface are responsible for the increased rate of this step, whereby GO and ERGO accelerate the process of electron donation to the MnO2 and to adsorbed oxygen atoms.

Matched MeSH terms: Oxygen
Evaluation of integrated anaerobic-aerobic biofilm reactor for degradation of azo dye methyl orange

Murali V, Ong SA, Ho LN, Wong YS

Bioresour Technol, 2013 Sep;143:104-11.
PMID: 23792659 DOI: 10.1016/j.biortech.2013.05.122

This study was to investigate the mineralization of wastewater containing methyl orange (MO) in integrated anaerobic-aerobic biofilm reactor with coconut fiber as bio-material. Different aeration periods (3h in phase 1 and 2; 3, 6 and 15 h in phase 3; 24 h in phase 4 and 5) in aerobic chamber were studied with different MO concentration 50, 100, 200, 200 and 300 mg/L as influent from phase 1-5. The color removals estimated from the standard curve of dye versus optical density at its maximum absorption wavelength were 97%, 96%, 97%, 97%, and 96% and COD removals were 75%, 72%, 63%, 81%, and 73% in phase 1-5, respectively. The MO decolorization and COD degradation followed first-order kinetic model and second-order kinetic model, respectively. GC-MS analysis indicated the symmetrical cleavage of azo bond and the reduction in aromatic peak ensured the partial mineralization of MO.

Matched MeSH terms: Biological Oxygen Demand Analysis
Fulltext Structural and photoluminescence studies on catalytic growth of silicon/zinc oxide heterostructure nanowires

Chong SK, Dee CF, Abdul Rahman S

Nanoscale Res Lett, 2013;8(1):174.
PMID: 23590803 DOI: 10.1186/1556-276X-8-174

Silicon/zinc oxide (Si/ZnO) core-shell nanowires (NWs) were prepared on a p-type Si(111) substrate using a two-step growth process. First, indium seed-coated Si NWs (In/Si NWs) were synthesized using a plasma-assisted hot-wire chemical vapor deposition technique. This was then followed by the growth of a ZnO nanostructure shell layer using a vapor transport and condensation method. By varying the ZnO growth time from 0.5 to 2 h, different morphologies of ZnO nanostructures, such as ZnO nanoparticles, ZnO shell layer, and ZnO nanorods were grown on the In/Si NWs. The In seeds were believed to act as centers to attract the ZnO molecule vapors, further inducing the lateral growth of ZnO nanorods from the Si/ZnO core-shell NWs via a vapor-liquid-solid mechanism. The ZnO nanorods had a tendency to grow in the direction of [0001] as indicated by X-ray diffraction and high resolution transmission electron microscopy analyses. We showed that the Si/ZnO core-shell NWs exhibit a broad visible emission ranging from 400 to 750 nm due to the combination of emissions from oxygen vacancies in ZnO and In2O3 structures and nanocrystallite Si on the Si NWs. The hierarchical growth of straight ZnO nanorods on the core-shell NWs eventually reduced the defect (green) emission and enhanced the near band edge (ultraviolet) emission of the ZnO.

Matched MeSH terms: Oxygen
Enhancement of bioseparation and dewaterability of domestic wastewater sludge by fungal treated dewatered sludge

Fakhru'l-Razi A, Molla AH

J Hazard Mater, 2007 Aug 17;147(1-2):350-6.
PMID: 17321676

A promising biological, sustainable, non-hazardous, safe and environmental friendly management and disposal technique of domestic wastewater sludge is global expectation. Fungal entrapped biosolids as a result of prior fungal treated raw wastewater sludge was recycled to evaluate its performance as inoculum for bioseparation/bioconversion of supplemented sludge in view of continuous as well as scale up wastewater sludge treatment. Encouraging results were achieved in bioseparation of suspended solids and in dewaterability/filterability of treated domestic wastewater sludge. Fungal entrapped biosolids offered 98% removal of total suspended solids (TSS) in supplemented sludge treatment at 6-day without nutrient (wheat flour, WF) supply. Consequently, 99% removal of turbidity and 87% removal of chemical oxygen demand (COD) were achieved in supernatant of treated sludge. The lowest value (1.75 x 10(12)m/kg) of specific resistance to filtration (SRF) was observed at 6-day after treatment, which was equivalent to the 70% decrease of SRF. The all results except SRF were not influenced further in treatments accompanied with WF supplementation. The present treatments offered significant (P

Matched MeSH terms: Oxygen
Fulltext Effects of Fiddler Crab Burrows on Sediment Properties in the Mangrove Mudflats of Sungai Sepang, Malaysia

Mokhtari M, Abd Ghaffar M, Usup G, Che Cob Z

Biology (Basel), 2016;5(1).
PMID: 26797647 DOI: 10.3390/biology5010007

In mangrove ecosystems, litter fall accumulates as refractory organic carbon on the sediment surface and creates anoxic sediment layers. Fiddler crabs, through their burrowing activity, translocate oxygen into the anoxic layers and promote aerobic respiration, iron reduction and nitrification. In this study, the effects of four species of fiddler crabs (Uca triangularis, Uca rosea, Uca forcipata and Uca paradussumieri) on organic content, water content, porosity, redox potential and solid phase iron pools of mangrove sediments were investigated. In each crab's habitat, six cores down to 30 cm depth were taken from burrowed and non-burrowed sampling plots. Redox potential and oxidized iron pools were highest in surface sediment, while porosity, water and organic content were higher in deeper sediment. Reduced iron (Fe (II)) and redox potential were significantly different between burrowed and non-burrowed plots. Crab burrows extend the oxidized surface layer down to 4 cm depth and through the oxidation effect, reduce the organic content of sediments. The effects of burrows varied between the four species based on their shore location. The oxidation effect of burrows enhance the decomposition rate and stimulate iron reduction, which are processes that are expected to play an important role in biogeochemical properties of mangrove sediments.

Matched MeSH terms: Oxygen
Fulltext Thermal and UV Hydrosilylation of Alcohol-Based Bifunctional Alkynes on Si (111) surfaces: How surface radicals influence surface bond formation

Khung YL, Ngalim SH, Scaccabarozi A, Narducci D

Sci Rep, 2015 Jun 12;5:11299.
PMID: 26067470 DOI: 10.1038/srep11299

Using two different hydrosilylation methods, low temperature thermal and UV initiation, silicon (111) hydrogenated surfaces were functionalized in presence of an OH-terminated alkyne, a CF3-terminated alkyne and a mixed equimolar ratio of the two alkynes. XPS studies revealed that in the absence of premeditated surface radical through low temperature hydrosilylation, the surface grafting proceeded to form a Si-O-C linkage via nucleophilic reaction through the OH group of the alkyne. This led to a small increase in surface roughness as well as an increase in hydrophobicity and this effect was attributed to the surficial etching of silicon to form nanosize pores (~1-3 nm) by residual water/oxygen as a result of changes to surface polarity from the grafting. Furthermore in the radical-free thermal environment, a mix in equimolar of these two short alkynes can achieve a high contact angle of ~102°, comparable to long alkyl chains grafting reported in literature although surface roughness was relatively mild (rms = ~1 nm). On the other hand, UV initiation on silicon totally reversed the chemical linkages to predominantly Si-C without further compromising the surface roughness, highlighting the importance of surface radicals determining the reactivity of the silicon surface to the selected alkynes.

Matched MeSH terms: Oxygen
FT-IR, NBO, HOMO-LUMO, MEP analysis and molecular docking study of Methyl N-({[2-(2-methoxyacetamido)-4-(phenylsulfanyl)phenyl]amino}[(methoxycarbonyl) imino]methyl)carbamate

Panicker CY, Varghese HT, Narayana B, Divya K, Sarojini BK, War JA, et al.

Spectrochim Acta A Mol Biomol Spectrosc, 2015 Sep 5;148:29-42.
PMID: 25863457 DOI: 10.1016/j.saa.2015.03.064

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of Methyl N-({[2-(2-methoxyacetamido)-4-(phenylsulfanyl) phenyl]amino} [(methoxycarbonyl)imino]methyl)carbamate have been investigated using HF and DFT levels of calculations. The geometrical parameters are in agreement with XRD data. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. Molecular electrostatic potential study was also performed. The first and second hyperpolarizability was calculated in order to find its role in nonlinear optics. Molecular docking studies are also reported. Prediction of Activity Spectra analysis of the title compound predicts anthelmintic and antiparasitic activity as the most probable activity with Pa (probability to be active) value of 0.808 and 0.797, respectively. Molecular docking studies show that both the phenyl groups and the carbonyl oxygens of the molecule are crucial for bonding and these results draw us to the conclusion that the compound might exhibit pteridine reductase inhibitory activity.

Matched MeSH terms: Oxygen
Measurement of the viscosity of irradiated silicone using a differential viscometer

Bradley DA, Dahlan KZ, Roy SC

Appl Radiat Isot, 2000 Oct;53(4-5):921-8.
PMID: 11003542

High-energy electron (2.0 MV) and gamma irradiation (60Co) has been used to modify polymeric silicone fluids of initial viscosities in the range, 90-700 cSt. Doses of electron and gamma radiation were delivered at rates of 0.246 kGy s(-1) and 15 kGy h(-1), respectively, exposure times being adjusted to ensure energy deposition in the range 30-360 kGy. Measurements were made using a differential viscometer based on a Bose Institute design. In line with expectation, samples of greater initial molecular weight (and hence greater viscosity), were observed to be more susceptible to radiation induced cross-linking than those of lower molecular weight. The role of dose rate and oxygen diffusion in determining the extent of change is discussed.

Matched MeSH terms: Oxygen
Microplankton bloom in a brackish water lagoon of Terengganu

Shamsudin L, Shazili NA

Environ Monit Assess, 1991 Oct;19(1-3):287-94.
PMID: 24233946 DOI: 10.1007/BF00401318

Increased primary plankton productivity was observed in a brackish water lagoon of Terengganu during the study period between January 1988 to December 1988. The lagoon is also the site for the fish cage culture activities of sea bass during the study period. An examination of water quality at the sampling stations during the study period indicated that both the organic and inorganic nutrients were high during the pre-monsoon period. The source of the nutrient in the lagoon was believed to be derived from the agro-based industrial effluents, fertilisers from paddy fields as well as untreated human and animal wastes. This coincided with the peak production of plankton in the surface waters of the brackish water lagoon. During this period both cultured and indigenous fish species were seen to suffer from oxygen asphyxiation (suffocation due to lack of oxygen). The primary productivity values ranged from 9 to 22 μg/L/h during the peak period while the microplankton species were composed of diatom, flagellates and dinoflagellates. Reduction in the primary productivity values were obtained with reduction in sallinity, specially during the peak monsoon months (November to March) corresponding to the Northeast monsoon period.

Matched MeSH terms: Oxygen
Fulltext The Role of Eif6 in Skeletal Muscle Homeostasis Revealed by Endurance Training Co-expression Networks

Clarke K, Ricciardi S, Pearson T, Bharudin I, Davidsen PK, Bonomo M, et al.

Cell Rep, 2017 Nov 07;21(6):1507-1520.
PMID: 29117557 DOI: 10.1016/j.celrep.2017.10.040

Regular endurance training improves muscle oxidative capacity and reduces the risk of age-related disorders. Understanding the molecular networks underlying this phenomenon is crucial. Here, by exploiting the power of computational modeling, we show that endurance training induces profound changes in gene regulatory networks linking signaling and selective control of translation to energy metabolism and tissue remodeling. We discovered that knockdown of the mTOR-independent factor Eif6, which we predicted to be a key regulator of this process, affects mitochondrial respiration efficiency, ROS production, and exercise performance. Our work demonstrates the validity of a data-driven approach to understanding muscle homeostasis.

Matched MeSH terms: Oxygen/metabolism; Reactive Oxygen Species/metabolism
Fulltext Silver (I) Dicyanonitrosomethanide, Ag[ONC(CN)2] Complex as Catalyst for the Selective Oxidation of Styrene to Benzaldehyde

Mohammad Anwar Mohamed Iqbal, Muhammad Zulhelmi Nazri, Mohammad Norazmi Ahmad, Erna Normaya Abdullah, Umie Fatihah Mohamad Haziz, Mohd Rizal Razali, et al.

Science Letters, 2020;14(2):71-84.
MyJurnal

Silver (I) dicyanonitrosomethanide, Ag[ONC(CN)2] represent a 3D interwoven coordination polymer organization in which all the donor atoms of the functional groups of ONC(CN)2- are coordinated to the Ag(I). Oxidation of styrene utilizing H2O2 as an oxidant in acetonitrile (CH3CN) was used as a model reaction to investigate the catalytic potential of the Ag (I) complex. The CH3CN was chosen as the solvent based on the data collected from Conductor like Screening Model for Real Solvents (COSMO-RS) study. The data indicate that the Ag [ONC(CN)2] complex was compatible and soluble in CH3CN. Different parameters such as styrene:H2O2 molar ratio, reaction time, catalyst mass, and reaction temperature were studied. Highest styrene conversion (36%) with 100% selectivity towards benzaldehyde (BZ) was achieved when 25 mg catalyst, 1:1 styrene to H2O2 molar ratio were used. The reaction was carried out at 303 K for 3 h. The catalytic conversion of styrene to BZ is proposed to take place via [Ag-H2O2] adduct with styrene oxide (StO) as an intermediate. Molecular Electrostatic Potential (MEP) shows that the Ag atom has the highest probability to coordinate with the oxygen atom of H2O2. The MEP data confirms the proposed mechanism.

Matched MeSH terms: Oxygen
Fulltext Bioavailability of zinc oxide nano particle with fly ash soil for the remediation of metals by Parthenium hysterophorus

Ahmad A, Ghufran R, Al-Hosni TK

J Environ Health Sci Eng, 2019 Dec;17(2):1195-1203.
PMID: 32030185 DOI: 10.1007/s40201-019-00434-2

To investigate the interaction of zinc oxide nanoparticles (ZnO NPs) with fly ash soil (FAS) for the reduction of metals from FAS by Parthenium hysterophorus were studied. The average accumulation of metals by P. hysterophorus stem were Fe 79.6%; Zn 88.5%; Cu 67.5%; Pb 93.6%; Ni 43.5% and Hg 39.4% at 5.5 g ZnO NP. The concentration of ZnO NP at 1.5 g did not affect the metals accumulation, however at 5.5 g ZnO NP showed highest metal reduction was 96.7% and at 10.5-15.5 g ZnO NP of 19.8%. The metal reduction rate was R
max
for Fe 16.4; Zn 21.1; Pb 41.9; Hg 19.1 was higher than Ni 6.4 and Cu 11.3 from the FAS at 5.5 g ZnO NP whereas, the reduction rate of Pb showed highest. With doses of 5.5 g ZnO NP the biomass increased upto 78%; the metal reduced upto 98.7% with the share of 100% ZnO NP from FAS. Further investigation with phytotoxicity the plant reactive oxygen species (ROS) production were affected due was mainly due to the recovery of metals from FAS (R2 = 0.99).

Matched MeSH terms: Reactive Oxygen Species
Evaluation of wastewater treatment performance to a field-scale constructed wetland system at clogged condition: A case study of ammonia manufacturing plant

Keng TS, Samsudin MFR, Sufian S

Sci Total Environ, 2021 Mar 10;759:143489.
PMID: 33248782 DOI: 10.1016/j.scitotenv.2020.143489

Assessment of the treatment performance in the field-scale hybrid constructed wetland (CW) for ammonia manufacturing plant remains limited. After being in operations running on and off since 2014, the hybrid CW which treats effluent from the ammonia manufacturing plant in Peninsular, Malaysia has recently demonstrated the full clogging to the CW. It takes only 8 months to demonstrate a big deterioration of performance in 2019. Though the mechanism of clogging is not clear, which can be partially from inherent design problems or operational issues, nonetheless, it is important to evaluate how this clogging has impacted the effluent treatment performance and the continuous utilization of the CW. The purpose of this study is to evaluate the impact of the treatment performance on the ammoniacal nitrogen and COD removal when the CW is clogged. The result revealed that there is no impact on COD removal, but it has a substantial impact on the ammoniacal nitrogen removal. The ammoniacal nitrogen removal dropped to negative (outlet concentration is higher than inlet concentration) during the clogged period. Another observation is, the low removal rate also coincides with a high COD/N ratio, when the COD/N ratio increased to >2, the ammoniacal nitrogen removal rate dropped substantially, with the coefficient of determination, R2 of 40.5%. The root cause for the clogging to develop in a short period of time is unidentified. However, it is still worth noting that COD and ammoniacal nitrogen efficiency did not behave the same at the clogged CW.

Matched MeSH terms: Biological Oxygen Demand Analysis

Filters

Please provide feedback to Administrator ([email protected])

External Links