Displaying publications 181 - 200 of 1115 in total

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  1. Hassan M, Yahya A, Okamoto T
    In this paper, we report the effect of BaAl2O4 addition (0-30 wt. %) on power consumption and oxygen sensing response of hot-spots developed on short Er123 ceramic rods of around 12 mm length synthesized using standard solid-state reaction. All the sensor rods showed increase in output current with increasing voltage followed by sudden reduction in output current and appearance of hot spot. After appearance of hot spot, for each rod, output current was observed to decrease gradually with increasing voltage with the slope of the I-V curve gradually approaching zero. Output current after the hot spot formation showed sensitivity to oxygen partial pressure, pO2 between 1 to 100 kPa. Addition of 30 wt. % BaAl2O4 reduced the fluctuation of current and increased the sensitivity for pO2 below 10 kPa. In addition, overshoot current was also reduced and resulted in improvement of response time from around 10 s to 5 s. Our result also showed that minimum power consumption was significantly reduced in the Er123 rods with 30 wt. % BaAl2O4.
    Matched MeSH terms: Oxygen
  2. Chong KC, Lai SO, Lau WJ, Thiam HS, Ismail AF, Roslan RA
    Polymers (Basel), 2018 Jan 28;10(2).
    PMID: 30966162 DOI: 10.3390/polym10020126
    Air pollution is a widely discussed topic amongst the academic and industrial spheres as it can bring adverse effects to human health and economic loss. As humans spend most of their time at the office and at home, good indoor air quality with enriched oxygen concentration is particularly important. In this study, polysulfone (PSF) hollow fiber membranes fabricated by dry-jet wet phase inversion method were coated by a layer of polydimethylsiloxane (PDMS) or poly(ether block amide) (PEBAX) at different concentrations and used to evaluate their performance in gas separation for oxygen enrichment. The surface-coated membranes were characterized using SEM and EDX to determine the coating layer thickness and surface chemical properties, respectively. Results from the gas permeation study revealed that the PSF membrane coated with PDMS offered higher permeance and selectivity compared to the membrane coated with PEBAX. The best performing PDMS-coated membrane demonstrated oxygen and nitrogen gas permeance of 18.31 and 4.01 GPU, respectively with oxygen/nitrogen selectivity of 4.56. Meanwhile, the PEBAX-coated membrane only showed 12.23 and 3.11 GPU for oxygen and nitrogen gas, respectively with a selectivity of 3.94. It can be concluded the PDMS coating is more promising for PSF hollow fiber membrane compared to the PEBAX coating for the oxygen enrichment process.
    Matched MeSH terms: Oxygen
  3. Wan Razarinah W, Zalina MN, Noorlidah Abdullah
    Sains Malaysiana, 2015;44:309-316.
    The study monitored the characteristics of the leachate collected from ten different landfills and presented the experimental work for the treatment of leachate by immobilized Trametes menziesii. Variation in biological oxygen demand (BOD), chemical oxygen demand (COD) and ammoniacal nitrogen (NH3-N) showed that the age of the leachate has a significant effect on its characteristics and composition. The BOD5/COD ratio tends to decrease as the age of leachate increases, varying from 0.71 for a relatively 'fresh' leachate to 0.62 for an older (more stabilized) one. Variations in the characteristics of the leachate suggested that these leachates are difficult to treat. The principal pollutants in the leachate samples were organic and ammonia loads. Treatment of leachate using immobilized Trametes menziesii achieved 89.14 and 2.11% removals for leachate BOD5 and COD, respectively. These findings suggested that using immobilized Trametes menziesii can remove promising percentage of BOD and COD leachate.
    Matched MeSH terms: Biological Oxygen Demand Analysis
  4. Wan Fadhilah Khalik, Ong SA, Wong YS, Nik Athirah Yusoff, Fahmi Ridwan, Ho LN
    Sains Malaysiana, 2015;44:607-612.
    In this study, the photocatalytic degradation of batik wastewater in the presence of zinc oxide (ZnO) as photocatalyst was
    investigated. The effect of various operating parameters, such as pH of batik wastewater, catalyst dosage and aeration
    on the photocatalytic degradation process, was examined. The mineralization of batik wastewater was also evaluated
    through chemical oxygen demand analysis. The decolorization of batik wastewater was enhanced at acidic conditions
    (pH3) which was 88.2% after 10 h irradiated under solar light, meanwhile its mineralization was 286 mg/L after 12 h
    irradiation time. The data obtained for photocatalytic degradation of batik wastewater was well fitted with the LangmuirHinshelwood
    kinetic model. It can be concluded that batik wastewater could be decolorized and mineralized under solar
    light irradiation with presence of ZnO.
    Matched MeSH terms: Biological Oxygen Demand Analysis
  5. Abdul Aziz Ahmad, Raihan Othman, Faridah Yusof, Mohd Firdaus Abdul Wahab
    Sains Malaysiana, 2014;43:459-465.
    A hybrid biofuel cell, a zinc-air cell employing laccase as the oxygen reduction catalyst is investigated. A simple cell design is employed; a membraneless single chamber and a freely suspended laccase in the buffer electrolyte. The cell is characterised based on its open-circuit voltage, power density profile and galvanostatic discharge at 0.5 mA. The activity of laccase as an oxidoreductase is substantiated from the cell discharge profiles. The use of air electrode in the cell design enhanced the energy output by 14%. The zinc-air biofuel cell registered an open-circuit voltage of 1.2 V and is capable to deliver a maximum power density of 1.1 mWcm-2 at 0.4 V. Despite its simple design features, the power output is comparable to that of biocatalytic cell utilising a much more complex system design.
    Matched MeSH terms: Oxygen
  6. Normawaty Mohammad-Noor, Asilah Al-Has, Aung T, Shahbudin Saad
    Sains Malaysiana, 2016;45:595-599.
    Benthic dinoflagellates are known to occur in the water column. The reason they can be found in different parts of the ecosystem is not clear. This study aims to determine the species and the cell abundance of benthic dinoflagellates in the water column and macrophytes collected from two different locations i.e. semi-enclosed lagoon and open coastal waters. The physico-chemical parameters (temperature, salinity, pH, dissolved oxygen) and nutrients (nitrate and phosphate) were determined. Results showed that in the lagoon, the most abundant dinoflagellate species on the macrophytes was also the most abundant dinoflagellate species in the water column. The species that dominated the water column and marophytes in the lagoon was Bysmatrum caponii. In the coastal area the trend was not clear. Coolia dominated the macrophytes whereas Peridinium quinquecorne dominated the water column. The physico-chemical parameters determined were similar at both sites except for nutrients. Results show that type of substrates and different geomorphology effects benthic dinoflagellates cell abundance in the macrophytes and water column.
    Matched MeSH terms: Oxygen
  7. Mohammed Yahya Abdo, Wan Yaacob Wan Ahmad, Laily Bin Din, Nazlina Ibrahim
    Sains Malaysiana, 2017;46:83-89.
    A phytochemical study was conducted on the stems and leaves of Hedychium malayanum (Zingiberaceae). Three steroids
    namely stigmasterol (1), sitostenone (2) and stigmast-4-ene-3,6-dione (3) as well as one triterpene, lupenone (4) and
    one oxygenated sesquiterpene, caryophyllene oxide (5) were successfully isolated from the respective stems and leaves,
    utilizing several chromatographic techniques. Their structures were elucidated by spectroscopic means (IR, MS, NMR),
    and by comparison with the literature data.
    Matched MeSH terms: Oxygen
  8. Ling Ty, Lee Nyanti, Theresa Muan, Jongkar Grinang, Siong-fong Sim, Aazani Mujahid
    Sains Malaysiana, 2016;45:157-166.
    Determining the water quality of Bakun Reservoir 13 months after it operates at full supply level is crucial for better understanding of changes in the physicochemical parameters, which may enable the prediction of its effects on the survival of aquatic life in the reservoir. This study determined 13 physicochemical parameters at six stations within the reservoir at fixed depths. The results showed that the minimum 5 mg/L of dissolved oxygen (DO) required for sensitive aquatic organisms was recorded at 6 m depth. However, DO was not detectable at depths exceeding 7 m. The water was acidic at depths of more than 10 m. Turbidity and total suspended solids increased corresponding with depth. Inorganic nitrogen were predominantly in the form of ammonia-nitrogen, creating an unhealthy environment for aquatic life. Concentration of Chl-a was significantly higher at the subsurface water than 30 m depth in four out of six stations. The present study shows changes in water quality as compared to the pre-impounded period and 15 months after the filling phase, in particular, stratification of dissolved oxygen, thermocline conditions and alkalinity. The changes varied according to the distance from the dam and may have been influenced by existing land developments within the area such as the construction of the Murum Hydroelectric Dam, oil palm plantations and timber concessionares. Though the water quality might have deteriorated, further study is needed to determine if this condition will prolong.
    Matched MeSH terms: Oxygen
  9. Lim SP
    JUMMEC, 1996;1:9-16.
    Research into ischaemia and reperfusion injury especially in liver transplantation has been aimed primarily at preventing deterioration of organ function before harvest and at improving organ preservation techniques. Recent studies however, suggest that postischaemic organ function and viability can be improved not only through improved organ protection before ischaemia, but also with therapy aimed at ameliorating the organ reperfusion injury. In order to develop successful therapeutic interventions against ischaemia-reperfusion induced liver injury, it is necessary to consider the primary site of injury as well as to explore the mechanism(s) and possible factors which may contribute to the injury during ischaemia and reperfusion. Studies on hepatic ischaemia-reperfusion injury have focused mainly at hepatocellular level. Until recently, more attention has been drawn t o the important role of hepatic microcirculation on the pathophysiology of the above injury. The argument that hepatic microvasculature is the primary site of ischaemia-reperfusion injury and possible factors which cause this injury are among the issues reviewed in this article. KEYWORDS: ischaemia, reperfusion, liver, microvasculature, oxygen radicals
    Matched MeSH terms: Oxygen
  10. Fitriani N, Kusuma MN, Wirjodirdjo B, Hadi W, Hermana J, Ni'matuzahroh, et al.
    Heliyon, 2020 Sep;6(9):e04967.
    PMID: 33015386 DOI: 10.1016/j.heliyon.2020.e04967
    In a slow sand filter, a biological layer consisting of alluvial mud and various types of microorganisms grows and attaches to the sand media and forms a matrix called schmutzdecke. Changes to several factors, including the quality of raw water, filtration speed, and the addition of media, affect the performance of the slow sand filter unit in producing treated water. Geotextiles can be equipped to improve the performance of a slow sand filter in removing pollutants. The selection of several factors that affect slow sand filter performance can be used as a starting point for the engineering system to determine the best pattern of performance behavior. This approach was carried out by looking at the dynamic behavior patterns of slow sand filter system performance in treating raw water. This research has not yet been conducted extensively. The dynamic behavior pattern approach to the performance of the slow sand filter unit was used to obtain the behavior model for the schmutzdecke layer on the filter. The system dynamic approach focused on treatment scenarios that can determine the behavior of the slow sand filter system. Several factors were assessed, including temperature, turbidity, nutrient concentration, algal concentration, bacteria and dissolved oxygen. Model simulation results show that the comparison of C: N: P values affected the performance of the schmutzdecke layer in removing total coli. The slow sand filter unit was capable of producing treated water with a total amount of coli equal to 0 on the C: N: P values of 85: 5.59: 1.25, respectively, and a 9 cm geotextile thickness.
    Matched MeSH terms: Oxygen
  11. Nor Faekah I, Fatihah S, Mohamed ZS
    Heliyon, 2020 Mar;6(3):e03594.
    PMID: 32258460 DOI: 10.1016/j.heliyon.2020.e03594
    A bench-scale model of a partially packed upflow anaerobic fixed film (UAF) reactor was set up and operated at five different hydraulic retention times (HRTs) of (17, 14, 10, 8, and 5) days. The reactor was fed with synthetic rubber wastewater consisting of a chemical oxygen demand (COD) concentration of 6355-6735 mg/L. The results were analyzed using the Monod model, the Modified Stover-Kincannon models, and the Grau Second-Order Model. The Grau Second-Order model was found to best fit the experimental data. The biokinetic constant values, namely the growth yield coefficient (Y) and the endogenous coefficient (Kd) were 0.027 g VSS/g COD and 0.1705 d-1, respectively. The half-saturation constant (Ks) and maximum substrate utilization rate (K) returned values of 84.1 mg/L and 0.371 d-1, respectively, whereas the maximum specific growth rate of the microorganism (μmax) was 0.011 d-1. The constants, Umax and KB, of the Stover-Kincannon model produced values of 6.57 g/L/d and 6.31 g/L/d, respectively. Meanwhile, the average second-order substrate removal rate, ks(2), was 105 d-1. These models gave high correlation coefficients with the value of R2 = 80-99% and these indicated that these models can be used in designing UAF reactor consequently predicting the behaviour of the reactor.
    Matched MeSH terms: Biological Oxygen Demand Analysis
  12. Liew HS, Mai CW, Zulkefeli M, Madheswaran T, Kiew LV, Delsuc N, et al.
    Molecules, 2020 Sep 12;25(18).
    PMID: 32932573 DOI: 10.3390/molecules25184176
    Photodynamic therapy (PDT) is emerging as a significant complementary or alternative approach for cancer treatment. PDT drugs act as photosensitisers, which upon using appropriate wavelength light and in the presence of molecular oxygen, can lead to cell death. Herein, we reviewed the general characteristics of the different generation of photosensitisers. We also outlined the emergence of rhenium (Re) and more specifically, Re(I) tricarbonyl complexes as a new generation of metal-based photosensitisers for photodynamic therapy that are of great interest in multidisciplinary research. The photophysical properties and structures of Re(I) complexes discussed in this review are summarised to determine basic features and similarities among the structures that are important for their phototoxic activity and future investigations. We further examined the in vitro and in vivo efficacies of the Re(I) complexes that have been synthesised for anticancer purposes. We also discussed Re(I) complexes in conjunction with the advancement of two-photon PDT, drug combination study, nanomedicine, and photothermal therapy to overcome the limitation of such complexes, which generally absorb short wavelengths.
    Matched MeSH terms: Oxygen/chemistry; Reactive Oxygen Species/chemistry
  13. Hay JX, Wu TY, Juan JC, Md Jahim J
    Environ Sci Pollut Res Int, 2017 Apr;24(11):10354-10363.
    PMID: 28281053 DOI: 10.1007/s11356-017-8557-9
    Although a significant amount of brewery wastewater (BW) is generated during beer production, the nutrients in the BW could be reused as a potential bio-resource for biohydrogen production. Therefore, improvements in photofermentative biohydrogen production due to a combination of BW and pulp and paper mill effluent (PPME) as a mixed production medium were investigated comprehensively in this study. The experimental results showed that both the biohydrogen yield and the chemical oxygen demand removal were improved through the combination of BW and PPME. The best biohydrogen yield of 0.69 mol H2/L medium was obtained using the combination of 10 % BW + 90 % PPME (10B90P), while the reuse of the wastewater alone (100 % BW and 100 % PPME) resulted in 42.3 and 44.0 % less biohydrogen yields than the highest yield, respectively. The greatest light efficiency was 1.97 % and was also achieved using the combination of both wastewaters at 10B90P. This study revealed the potential of reusing and combining two different effluents together, in which the combination of BW and PPME improved the nutrients and light penetration into the mixed production medium.
    Matched MeSH terms: Biological Oxygen Demand Analysis
  14. Nazarudin, B., Khairulamir, Z., Azarinah, I., Jaafarm, M.Z., Karis, M., Esa, K.
    MyJurnal
    This was a prospective randomised study comparing carboxyhaemoglobin concentrations between low-flow anaesthesia (fresh gas flow 1.0 L/min) and minimal-flow anaesthesia (0.5 L/min) using desflurane. Sixty (ASA 1 or 2) adult patients undergoing elective surgery under general anaesthesia were randomly allocated to receive either low-flow (Group 1) or minimal flow anaesthesia (Group 2). Venous blood samples for carboxyhaemoglobin levels were taken at baseline and at 10 mins intervals for 40 mins. Both groups showed significant increase in carboxyhaemoglobin concentrations within the first 10 mins when fresh gas flow of 4.0 L/min was used. Reduction in carboxyhemoglobin levels was seen after 20 mins of minimal or low flow anaesthesia. However, there was no significant difference in the magnitude of reduction of carboxyhemoglobin concentrations between the groups. The fractional inspired of oxygen (FiO2) showed no significant changes in either group. In conclusion, desflurane usage in anaesthesia with either low-flow or minimal-flow was not associated with increased carboxyhaemoglobin concentrations.
    Matched MeSH terms: Oxygen
  15. Wee, Siaw Khur, Chok, Vui Soon, Gorin, Alexander, Chua, Han Bing, Yan, Hong Ming
    MyJurnal
    Compartmented Fluidized Bed Gasifier (CFBG), consisting of two compartments - the combustorand gasifier, uses air blown instead of pure oxygen for syngas production in bubbling fluidization mode, eliminating the need of air separation unit, and reducing the capital cost, thus distinguishes it from other traditional ones. Fluidization quality is a determining factor in the CFBG to guarantee its well-lifted behaviour. Previous study, without solid circulation at ambient conditions, brought to the fore the necessity of considering the effect of the minimum allowable effective diameter. The study was then performed in the CFBG cold physical model of 0.66m overall diameter (effective diameter for combustor and gasifier is 0.413m and 0.257m) to investigate the fluidization quality and compare it with the results obtained from the previous cold model of about 1.36 times smaller, but with the same compartmented ratio of 65:35. Different inert particles (river sand, quartz sand and alumina) were used, over a range of aspect ratios, for the aforementioned objective. The results showed that the fluidization quality in the gasifier has not been achieved and the degradation of fluidization quality in the combustor is still observed, notwithstanding the fact that the condition of the minimum allowable effective diameter has been met. The reduction of distributor free area, to increase the distributor pressure drop, showed a marginal effect on the quality. The effect of the minimum allowable effective diameter on fluidization quality in CFBG as well as the interplay of geometric and operational parameters require further studies be carried out. The fluidization quality of the binary mixture is also currently under investigation.
    Matched MeSH terms: Oxygen
  16. Mohd Abdul Fatah Abdul Manan, M. Ibrahim M. Tahir, Crouse, Karen A., How, Fiona N.-F., Watkin, David J.
    MyJurnal
    The crystal structure of the title compound has been determined. The compound crystallized in the triclinic space group P -1, Z = 2, V = 1839.42(18) Å3 and unit cell parameters a = 11.0460(6) Å, b = 13.3180(7) Å, c = 13.7321(8) Å, a = 80.659(3)°, ß = 69.800(3)° and ? = 77.007(2)° with one disordered dimethylsulfoxide solvent molecule with the sulfur and oxygen atoms are distributed over two sites; S101/S102 [site occupancy factors: 0.6035/0.3965] and O130/O131 [site occupancy factor 0.3965/0.6035]. The C22-S21 and C19-S20 bond distances of 1.779(7) Å and 1.788(8) Å indicate that both of the molecules are connected by the disulfide bond [S20-S21 2.055(2) Å] in its thiol form. The crystal structure reveals that both of the 5-bromoisatin moieties are trans with respect to the [S21-S20 and C19-N18] and [S20-S21 and C22-N23] bonds whereas the benzyl group from the dithiocarbazate are in the cis configuration with respect to [S21-S20 and C19-S44] and [S20-S21 and C22-S36] bonds. The crystal structure is further stabilized by intermolecular hydrogen bonds of N9-H35···O16 formed between the two molecules and N28-H281···O130, N28-H281···O131 and C41-H411···O131 with the solvent molecule.
    Matched MeSH terms: Oxygen
  17. Hazwani Ahmad Yusof, Rabinderjeet Singh, Zainuddin Zafarina, Kieron Rooney, Ahmad Munir Che Muhamed
    MyJurnal
    The purpose of this study was to examine the effect of the ACE I/D gene polymorphism on athletic status and physical performance of well-trained Malaysian athletes. The distribution of ACE I/D gene polymorphism among 180 well trained athletes was compared with 180 sedentary controls. 20 meter Yo-Yo intermittent recovery and leg strength tests were used to measure maximal oxygen consumption (VO2max) and leg strength value of athletes with different ACE I/D genotype, respectively. Chi-Square and one way ANOVA tests were used for data analysis. The II and DD genotype were more prevalent among the endurance athletes and the strength/ power athletes compared to the other groups, respectively (p=0.00). The VO2max was not significantly associated with ACE genotype in athlete (p=0.828). However, athletes with the DD genotype had recorded a greater result for leg strength (113.8 ± 36.2) than those with the II (96.2 ± 28.0) and the ID (112.2 ± 33.5) genotype (p=0.047). This study supports the notion that ACE I/D gene polymorphism might be a genetic factor associated with athletic status and strength performance among the Malaysian population. Future studies with more representation of endurance athletes might able to detect the association between I allele and endurance performance.
    Matched MeSH terms: Oxygen Consumption
  18. Niekla S. Andiesta, Zeinab Abbas Hasan, Chooi Gait Toh
    MyJurnal
    Pain and anxiety management is of paramount importance in dentistry especially for child patients. The term “Medicated Oxygen” or “Magic Air” refers to a mixture of nitrous oxide and oxygen gases that is commonly used for partial sedation in pediatric dental populations. The gas is colorless and virtually odorless with a faint, sweet smell. Nitrous oxide sedation is administered by inhalation, absorbed by diffusion through the lungs, and eliminated via respiration. In children, sedation may accelerate the delivery of dental treatment that requires patient serenity and may allow the patient to tolerate unpleasant procedures by reducing anxiety, discomfort, or pain.
    Matched MeSH terms: Oxygen
  19. Tee PF, Abdullah MO, Tan IAW, Amin MAM, Nolasco-Hipolito C, Bujang K
    Environ Technol, 2018 Apr;39(8):1081-1088.
    PMID: 28417676 DOI: 10.1080/09593330.2017.1320433
    A microbial fuel cell (MFC) integrated with adsorption system (MFC-AHS) is tested under various operating temperatures with palm oil mill effluent as the substrate. The optimum operating temperature for such system is found to be at ∼35°C with current, power density, internal resistance (Rin), Coulombic efficiency (CE) and maximum chemical oxygen demand (COD) removal of 2.51 ± 0.2 mA, 74 ± 6 mW m-3, 25.4 Ω, 10.65 ± 0.5% and 93.57 ± 1.2%, respectively. Maximum current density increases linearly with temperature at a rate of 0.1772 mA m-2 °C-1, whereas maximum power density was in a polynomial function. The temperature coefficient (Q10) is found to be 1.20 between 15°C and 35°C. Present studies have demonstrated better CE performance when compared to other MFC-AHSs. Generally, MFC-AHS has demonstrated higher COD removals when compared to standalone MFC regardless of operating temperatures.

    ABBREVIATIONS: ACFF: activated carbon fiber felt; APHA: American Public Health Association; CE: Coulombic efficiency; COD: chemical oxygen demand; ECG: electrocardiogram; GAC: granular activated carbon; GFB: graphite fiber brush; MFC: microbial fuel cell; MFC-AHS: microbial fuel cell integrated with adsorption hybrid system; MFC-GG: microbial fuel cell integrated with graphite granules; POME: palm oil mill effluent; PTFE: polytetrafluoroethylene; SEM: scanning electron microscope.

    Matched MeSH terms: Biological Oxygen Demand Analysis
  20. Nur Aqilah Muhamad Darif, Nur Shakila Abdul Samad, Sazlina Salleh, Mahadi Mohammad, Noor Alia Ahmad Nordin, Aysha Mariam Mohamed Javeed, et al.
    Trop Life Sci Res, 2016;27(11):71-77.
    MyJurnal
    Benthic faunal communities are important components in the intertidal zones.
    The diversity and abundance of the benthic communities are subjected to different natural
    and anthropogenic disturbances. The study was conducted as one off sampling on 6th
    November 2013 (1) to investigate the abundance and distribution of soft sediment
    communities in relation to environmental variables and (2) investigate the changes of
    population structure and diversity using spatial scales of 1 m, 10 m, and 100 m. Results
    indicated a total of 110 individuals of macrobenthos consisting of 7 different groups
    (Annelida, Bivalvia, Crustacea, Gastropoda, Nematoda, Nemertea, Polychaeta) and 4
    different groups of meiobenthos (Copepoda, Nematoda, Ostracoda, Polychaeta)
    consisting 920 individuals were recorded. Dissolved oxygen played the most significant
    role in affecting the distribution of soft sediment communities while ammonia
    concentrations only affected marcobenthic organisms. However, sediment grain size did
    not show significant correlation (p>0.05) on soft sediment communities. Hence,
    understanding how different properties of benthos respond to changes in environmental
    variables is crucial in determining how the impacts on the sediment are tolerated by the
    benthic organisms.
    Matched MeSH terms: Oxygen
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