Displaying publications 161 - 180 of 283 in total

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  1. Fulltext Development of catalytic converter by washcoat of γ-alumina on nickel oxide (Nio) catalyst in FeCrAl substrate for exhaust emission control : proposed study
    Leman, A.M., Fatin Afiqah Jajuli, Dafit Feriyanto
    Journal of Occupational Safety and Health, 2015;12(2):65-70.
    MyJurnal
    Automobile exhaust emission control is one of the trending issues in automobile research field. It caused by high
    pollution such as carbon monoxide (CO), nitrogen oxides (NOx), and hydrocarbons (HC) distributed by automobile
    especially form diesel engine. These pollutants give a harmful effect to the environment and human health. Therefore,
    this paper proposed in reviewing methods on fabrication of modified catalytic converter. FeCrAl is used as substrate
    which treated using ultrasonic bath technique which could improve the exhaust emission control. This metallic catalytic converter used as the replacement of precious metal that have high production cost.
    Matched MeSH terms: Hydrocarbons
  2. Fulltext Evidence for strong, widespread chlorine radical chemistry associated with pollution outflow from continental Asia
    Baker AK, Sauvage C, Thorenz UR, van Velthoven P, Oram DE, Zahn A, et al.
    Sci Rep, 2016 11 15;6:36821.
    PMID: 27845366 DOI: 10.1038/srep36821
    The chlorine radical is a potent atmospheric oxidant, capable of perturbing tropospheric oxidative cycles normally controlled by the hydroxyl radical. Significantly faster reaction rates allow chlorine radicals to expedite oxidation of hydrocarbons, including methane, and in polluted environments, to enhance ozone production. Here we present evidence, from the CARIBIC airborne dataset, for extensive chlorine radical chemistry associated with Asian pollution outflow, from airborne observations made over the Malaysian Peninsula in winter. This region is known for persistent convection that regularly delivers surface air to higher altitudes and serves as a major transport pathway into the stratosphere. Oxidant ratios inferred from hydrocarbon relationships show that chlorine radicals were regionally more important than hydroxyl radicals for alkane oxidation and were also important for methane and alkene oxidation (>10%). Our observations reveal pollution-related chlorine chemistry that is both widespread and recurrent, and has implications for tropospheric oxidizing capacity, stratospheric composition and ozone chemistry.
    Matched MeSH terms: Hydrocarbons
  3. Profiles of bacterial assemblages from microplastics of tropical coastal environments
    Curren E, Leong SCY
    Sci Total Environ, 2019 Mar 10;655:313-320.
    PMID: 30471599 DOI: 10.1016/j.scitotenv.2018.11.250
    Plastic waste is a global issue of an increasing concern in aquatic ecosystems. Microplastics form a large proportion of plastic pollution in marine environments. Although microplastics are prevalent, their distribution along the coasts of tropical regions is not well studied. Microplastic pieces (1-5 mm) were collected from two distinct regions along the coastlines of Singapore, from the northern coast in the Johor Strait and the southern coast in the Singapore Strait. Microplastics were present in concentrations ranging from 9.20-59.9 particles per kg of dry sand sediment. The majority of microplastics identified were foam particles (55%) and fragments (35%). Microplastics were significantly more abundant on heavily populated beaches compared to pristine beaches. High throughput sequencing was used to profile the communities of bacteria on the surfaces of microplastic particles. The structure of the microbial communities was primarily characterised by Proteobacteria and Bacteroidetes and were distinct across sites. Hydrocarbon-degrading genera such as Erythrobacter were dominant in areas with heavy shipping and pollution. Potential pathogenic genera such as Vibrio and Pseudomonas were also identified. This study highlights the diverse bacterial assemblages present on marine microplastic surfaces and the importance of understanding the bacterial plastisphere.
    Matched MeSH terms: Hydrocarbons
  4. Fine motor skills and accident proneness of garments workers in Bangladesh
    Muhammad SH, Roy M
    Jurnal Psikologi Malaysia, 2014;olume 28:79-87.
    Accident in an organization is one of the most undesirable phenomenons all over the world. The consequences of accidents in workplace are numerous which include damages of resources and cost of lives of many workers. For example, in 1991 a major disaster occurred in U.S. at triangle Shirtwaist factory, which cost the life of 100 garments workers (Greenwald & Richard, 2005). In Bangladesh accidents in workplace are more frequent and devastating, for which Bangladesh has been criticized severely worldwide. Recently one of those unfortunate phenomenons in Bangladesh was fire at Nimtoli of old Dhaka which cost 117 people burnt alive in June 2010. Another accident took place in Tazreen Fashion, Dhaka in 2012 which caused at least 112 workers either burnt to death or died while trying to escape the blaze. These are the short picture of loss of lives. Yet the losses of resources are not few. Sometimes accidents create threats for human and animal kingdom also by large rate of environmental pollution. For Example, in 2005 devastating Texas City Refinery explosion cost lives of many workers as well as light hydrocarbons concentrated at ground level throughout a large surrounding area which caused long lasting environmental pollution (Baldwin & Lisa, 2008). Furthermore, economic loss cannot also be over looked. A little mistake costs huge loss in assembly line of work. Thus accidents reduce production rate, lessen the quality of product and the reputation of industry also.
    Matched MeSH terms: Hydrocarbons
  5. Effect of irradiance on the emission of short-lived halocarbons from three common tropical marine microalgae
    Lim YK, Keng FS, Phang SM, Sturges WT, Malin G, Abd Rahman N
    PeerJ, 2019;7:e6758.
    PMID: 31041152 DOI: 10.7717/peerj.6758
    Marine algae have been reported as important sources of biogenic volatile halocarbons that are emitted into the atmosphere. These compounds are linked to destruction of the ozone layer, thus contributing to climate change. There may be mutual interactions between the halocarbon emission and the environment. In this study, the effect of irradiance on the emission of halocarbons from selected microalgae was investigated. Using controlled laboratory experiments, three tropical marine microalgae cultures, Synechococcus sp. UMACC 371 (cyanophyte), Parachlorella sp. UMACC 245 (chlorophyte) and Amphora sp. UMACC 370 (diatom) were exposed to irradiance of 0, 40 and 120 µmol photons m-2s-1. Stress in the microalgal cultures was indicated by the photosynthetic performance (Fv/Fm, maximum quantum yield). An increase in halocarbon emissions was observed at 120 µmol photons m-2s-1, together with a decrease in Fv/Fm. This was most evident in the release of CH3I by Amphora sp. Synechococcus sp. was observed to be the most affected by irradiance as shown by the increase in emissions of most halocarbons except for CHBr3 and CHBr2Cl. High positive correlation between Fv/Fm and halocarbon emission rates was observed in Synechococcus sp. for CH2Br2. No clear trends in correlation could be observed for the other halocarbons in the other two microalgal species. This suggests that other mechanisms like mitochondria respiration may contribute to halocarbon production, in addition to photosynthetic performance.
    Matched MeSH terms: Hydrocarbons, Halogenated
  6. Petroleum source rock properties of the neogene bhuban shales, Bengal basin, Bangladesh
    Md. Farhaduzzaman, Wan Hasiah Abdullah, Md. Aminul Islam
    Sains Malaysiana, 2015;44:571-579.
    The present study evaluates the petroleum source rock generation potential of the Neogene Bhuban shales from Bangladesh.
    Organic geochemical and organic petrological methods were used for analyzing 11 drill core samples from 4 gas fields
    in the basin. Source rock potential, maceral composition, organic matter abundance, biomarker distribution, thermal
    maturity, hydrocarbon generation and depositional environment were evaluated. Kerogen in the studied shale samples
    is classified mainly as Type III with lesser amounts of Type II. Vitrinite is the dominant maceral group observed in the
    analyzed Bhuban samples followed by liptinite and inertinite. Vitrinite reflectance, Tmax and biomarker parameters
    indicate the thermal maturity ranges from just pre-oil window to mid-oil window. Based on its total organic carbon
    (TOC), extractable organic matter (EOM) and hydrogen index (HI), the analyzed Bhuban shales are ranked as mainly poor
    to fair source rocks but with good gas generation potential. The dominant terrestrial environment prevailed during the
    deposition of the studied Bhuban shales while the condition was sub-oxic as indicated by cross-plots of pristane versus
    phytane and sterane versus pristane/phytane ratios.
    Matched MeSH terms: Hydrocarbons
  7. Biodiesel production from fish (cyprinus carpio) waste and evaluation of engine performance
    Mohammed Saifuddin, Amru N. Boyce
    Sains Malaysiana, 2017;46:1771-1778.
    As fossil energy resources are depleting quick and energy security is playing a vital role in the world economy. Quest for alternative energy sources have turned researches investigation in waste foods for next generation fuel. Biodiesel is usually considered to be environmentally friendly as it reduces greenhouse gas emission. Fish wastes rich in fatty acids and can be used as the raw material to produce biodiesel through transesterification reaction. The results showed that the seven peaks are fatty acid methyl esters, indicating all the triglycerides were successfully methylated to methyl esters. Fish based biodiesel provided a significant reduction in carbon monoxide (CO) and hydrocarbon (HC) emissions under engine loads of 15 (Nm) and required no engine modification. The viscosity of the produced biodiesel was within the range of international standards (ASTM). The biodiesel was found to contain a low base number and exhibited a lower specific fuel consumption compared to the conventional diesel. It can be concluded that biodiesel derived from waste fish oil can be considered as a potential source of commercial biodiesel.
    Matched MeSH terms: Hydrocarbons
  8. Multimedia environmental fate and transport model of dichlorodiphenyltrichloroethane (DDT): case study sayong river watershed, Johor, Malaysia
    Ghani Z, Anuar A, Majid Z, Yoneda M
    Sains Malaysiana, 2017;46:2383-2392.
    This study describes the development of a multimedia environmental fate and transport model of dichlorodiphenyltrichloroethane (DDT) at Sungai Sayong watershed. Based on the latest estimated DDT emission, the DDT concentrations in air, soil, water and sediment as well as the transfer processes were simulated under the equilibrium and steady-state assumption. Model predictions suggested that soil and sediment was the dominant sink of DDT. The results showed that the model predicted was generally good agreement with field data. Compared with degradation reaction, advection outflow was more important processes occurred in the model. Sensitivities of the model estimates to input parameters were tested. The result showed that vapour pressure (Ps) and organic carbon water partition coefficient (KOC) were the most influential parameters for the model output. The model output-concentrations of DDT in multimedia environment is very important as it can be used in future for human exposure and risk assessment of organochlorine pesticides (OCPs) at Sungai Sayong Basin.
    Matched MeSH terms: Hydrocarbons, Chlorinated
  9. Fulltext Ultraviolet A and Ultraviolet C Light-Induced Reduction of Surface Hydrocarbons on Titanium Implants
    Naauman Z, Rajion ZAB, Maliha S, Hariy P, Muhammad QS, Noor HAR
    Eur J Dent, 2019 Feb;13(1):114-118.
    PMID: 31170762 DOI: 10.1055/s-0039-1688741
    OBJECTIVE: The carbon, titanium, and oxygen levels on titanium implant surfaces with or without ultraviolet (UV) pretreatment were evaluated at different wavelengths through X-ray photoelectron spectroscopy (XPS).

    MATERIALS AND METHODS: This interventional experimental study was conducted on nine Dio UFII implants with hybrid sandblasted and acid-etched (SLA) surface treatments, divided equally into three groups. Control group A samples were not given UV irradiation, while groups B and C samples were given UVA (382 nm, 25 mWcm2) and UVC (260 nm, 15 mWcm2) irradiation, respectively. The atomic ratio of carbon, titanium, and oxygen was compared through XPS.

    RESULTS: Mean carbon-to-titanium ratio and C1 peaks considerably increased in Group A compared to those in experimental Groups B and C. The intensity of Ti2p and O1s peaks was more pronounced for group C compared to that for groups A and B.

    CONCLUSIONS: Although the decrease in surface hydrocarbons was the same in both UV-treated groups, the peak intensity of oxygen increased in the UVC-treated group. Thus, it can be concluded that compared with UVA irradiation, UVC irradiation has the potential to induce more hydrophilicity on SLA-coated implants.

    Matched MeSH terms: Hydrocarbons
  10. Fulltext Preventing Hydrate Adhesion with Magnetic Slippery Surfaces
    Ragunathan T, Xu X, Shuhili JA, Wood CD
    ACS Omega, 2019 Oct 01;4(14):15789-15797.
    PMID: 31592451 DOI: 10.1021/acsomega.9b01232
    Hydrate formation is a common challenge in the oil and gas industry when natural gas is transported under cold conditions in the presence of water. Coatings are one of the solutions that have shown to be a promising approach to address this challenge. However, this strategy suffers from the intrinsic existence of a solid-liquid interface causing a high rate of hydrate nucleation and high hydrate adhesion strength. This proof-of-concept study highlights the performance of a magnetic slippery surface to prevent hydrate adhesion at atmospheric pressure using tetrahydrofuran hydrates. The coating consisted of a hydrocarbon-based magnetic fluid, which was applied to a metal surface to create an interface that lowered the hydrate adhesion strength on the surface. The performance of these new surfaces under static and dynamic (under fluid flow) conditions shows that the magnetic coating gel can be a potential inhibitor for hydrate adhesion as it reduced the torque value after the formation of hydrates.
    Matched MeSH terms: Hydrocarbons
  11. Fulltext Investigating the Applicability of Molecular Dynamics Simulation for Estimating the Wettability of Sandstone Hydrocarbon Formations
    Khosravi V, Mahmood SM, Zivar D, Sharifigaliuk H
    ACS Omega, 2020 Sep 15;5(36):22852-22860.
    PMID: 32954134 DOI: 10.1021/acsomega.0c02133
    One of the techniques to increase oil recovery from hydrocarbon reservoirs is the injection of low salinity water. It is shown that the injection of low salinity water changes the wettability of the rock. However, there are argumentative debates concerning low salinity water effect on changing the wettability of the oil/brine/rock system in the oil reservoirs. In this regard, molecular dynamics simulation (MDS) as a tool to simulate the phenomena at the molecular level has been used for more than a decade. In this study, the Zisman plot (presented by KRUSS Company) was simulated through MDS, and then, contact angle experiments for n-decane interactions on the Bentheimer substrate in the presence of different concentrations of sodium ions were conducted. MDS was then used to simulate experiments and understand the wettability trend based on free-energy calculations. Hereafter, a new model was developed in this study to correlate free energies with contact angles. The developed model predicted the experimental results with high accuracy (R2 ∼ 0.98). A direct relation was observed between free energy and water contact angle. In contrast, an inverse relation was noticed between the ion concentration and the contact angle such that an increase in the ion concentration resulted in a decrease in the contact angle and vice versa. In other terms, increasing brine ionic concentrations in the presence of n-decane is linked to a decrease in free energies and an increase in the wetting state of a sandstone. The comparison between the developed model's predicted contact angles and experimental observations showed a maximum deviation of 14.32%, which is in satisfactory agreement to conclude that MDS can be used as a valuable and economical tool to understand the wettability alteration process.
    Matched MeSH terms: Hydrocarbons
  12. Fulltext Effect of Sand Fines Concentration on the Erosion-Corrosion Mechanism of Carbon Steel 90° Elbow Pipe in Slug Flow
    Khan R, H Ya H, Pao W, Majid MAA, Ahmed T, Ahmad A, et al.
    Materials (Basel), 2020 Oct 16;13(20).
    PMID: 33081078 DOI: 10.3390/ma13204601
    Erosion-corrosion of elbow configurations has recently been a momentous concern in hydrocarbon processing and transportation industries. The carbon steel 90° elbows are susceptible to the erosion-corrosion during the multiphase flow, peculiarly for erosive slug flows. This paper studies the erosion-corrosion performance of 90° elbows at slug flow conditions for impact with 2, 5, and 10 wt.% sand fines concentrations on AISI 1018 carbon steel exploiting quantitative and qualitative analyses. The worn surface analyses were effectuated by using laser confocal and scanning electron microscopy. The experiment was conducted under air and water slug flow containing sand fines of 50 µm average size circulated in the closed flow loop. The results manifest that with the increase of concentration level, the erosion-corrosion magnitude increases remarkably. Sand fines instigate the development of perforation sites in the form of circular, elongated, and coalescence pits at the elbow downstream and the corrosion attack is much more obvious with the increase of sand fines concentration. Another congruent finding is that cutting and pitting corrosion as the primitive causes of material degradation, the 10 wt.% sand fines concentration in carrier phase increases the erosion-corrosion rate of carbon steel up to 93% relative to the 2 wt.% sand fines concentration in slug flow.
    Matched MeSH terms: Hydrocarbons
  13. Fulltext Hybrid Polymerisation: An Exploratory Study of the Chemo-Mechanical and Rheological Properties of Hybrid-Modified Bitumen
    Joohari IB, Giustozzi F
    Polymers (Basel), 2020 Apr 18;12(4).
    PMID: 32325743 DOI: 10.3390/polym12040945
    In this study, the mechanical and rheological properties of hybrid polymer-modified bitumen (PMB) have been investigated. For this purpose, nine different polymers-including crumb rubber, elastomers and plastomers at varying content-were studied to evaluate their mechanical performance as single polymers, first, and as a combination of two or more polymers as a hybrid polymer blend. Subsequently, the hybrid polymer blends were added in a relatively small percentage into the base bitumen to study its influence on the rheological performance of hybrid PMB. The mechanical properties identified from the analysis of the stress-strain curve of the single polymers were the Young's Modulus, tensile stress, and elongation at break. The chemical structure of the polymer hybrid blends was analysed using FTIR, followed by frequency sweep tests conducted using the dynamic shear rheometer (DSR) to determine the bitumen rheological properties. Results showed that hybrid PMB enhances the viscoelastic behaviour of bitumen at both low and high temperature compared to other PMBs only including single polymers.
    Matched MeSH terms: Hydrocarbons
  14. Fulltext Permanent deformation investigation of rubber polymer modified binder in superpave hot mix asphalt mixture
    Ekarizan Shaffie1, Ahmad Kamil Arshad, Ramadhansyah Putra Jaya, Khairil Azman Masri, Wardati Hashim
    Journal of Academia Universiti Teknologi MARA Negeri Sembilan, 2020;8(1):45-52.
    MyJurnal
    Moisture susceptibiltiy is one of the common types of pavement failure found in asphaltic pavements.
    Climatic factor such as temperature and moisture has a profound effect on the durability of hot mix
    asphalt pavements. Couple with high traffic loads/stresses made stripping of pavement materials
    inevitable. Thus, it has become necessary to improve the efficiency of the design of hot mix asphalt
    (HMA) for better performance and safe riding comfort. This study investigates and discusses the findings
    on the stripping performance of dense graded Superpave mixes using two type of binder; un-modified
    binder and rubber polymer modified binder (RPM) using Superpave mix design (AASHTO TP4)
    procedure. The RPM binder consists of 4% of both rubber crumb and EVA polymer. Modified Lottman
    and Resilient Modulus tests were used to evaluate the stripping performance in these mixtures and this
    study also documents the effect of different temperature on tensile strength ratio (TSR) and resilient
    modulus ratio (RMR) on the HMA mixtures. Experimental evidences show that the RPM binder mixes
    were found to have significantly improved the resistance to moisture damage compared to unmodified
    binder mixtures. The RPM binder application may able to alleviate problems related to aggregate
    stripping and potholes on our road. Statistical analysis showed good correlation between resilient
    modulus and tensile strength ratio.
    Matched MeSH terms: Hydrocarbons
  15. Role of nanocatalyst in the treatment of organochlorine compounds - A review
    El-Sheikh MA, Hadibarata T, Yuniarto A, Sathishkumar P, Abdel-Salam EM, Alatar AA
    Chemosphere, 2020 Nov 04.
    PMID: 33220978 DOI: 10.1016/j.chemosphere.2020.128873
    Since a few centuries ago, organochlorine compounds (OCs) become one of the threatened contaminants in the world. Due to the lipophilic and hydrophobic properties, OCs always discover in fat or lipid layers through bioaccumulation and biomagnification. The OCs are able to retain in soil, sediment and water for long time as it is volatile, OCs will evaporate from soil and condense in water easily and frequently, which pollute the shelter of aquatic life and it affects the function of organs and damage system in human body. Photocatalysis that employs the usage of semiconductor nanophotocatalyst and solar energy can be the possible alternative for current conventional water remediation technologies. With the benefits of utilizing renewable energy, no production of harmful by-products and easy operation, degradation of organic pollutants in rural water bodies can be established. Besides, nanophotocatalyst that is synthesized with nanotechnology outnumbered conventional catalyst with larger surface area to volume ratio, thus higher photocatalytic activity is observed. In contrast, disadvantages particularly no residual effect in water distribution network, requirement of post-treatment and easily affected by various factors accompanied with photocatalysis method cannot be ignored. These various factors constrained the photocatalytic efficiency via nanocatalysts which causes the full capacity of solar photocatalysis has yet to be put into practice. Therefore, further modifications and research are still required in nanophotocatalysts' synthesis to overcome limitations such as large band gaps and photodecontamination.
    Matched MeSH terms: Hydrocarbons, Chlorinated
  16. Soft computing-based modeling and emission control/reduction of a diesel engine fueled with carbon nanoparticle-dosed water/diesel ‎emulsion fuel
    Atarod P, Khlaife E, Aghbashlo M, Tabatabaei M, Hoang AT, Mobli H, et al.
    J Hazard Mater, 2021 04 05;407:124369.
    PMID: 33160782 DOI: 10.1016/j.jhazmat.2020.124369
    This study was set up to model and optimize the performance and emission characteristics of a diesel engine fueled with carbon nanoparticle-dosed water/‎diesel emulsion fuel using a combination of soft computing techniques. Adaptive neuro-fuzzy inference system tuned by particle ‎swarm algorithm was used for modeling the performance and emission parameters of the engine, while optimization of the engine operating parameters and the fuel composition was conducted via multiple-objective particle ‎swarm algorithm. The model input variables were: injection timing (35-41° CA BTDC), engine load (0-100%), nanoparticle dosage (0-150 μM), and water content (0-3 wt%). The model output variables included: brake specific fuel consumption, brake thermal efficiency, as well as carbon monoxide, carbon dioxide, nitrogen oxides, and unburned hydrocarbons emission concentrations. The training and testing of the modeling system were performed on the basis of 60 data patterns obtained from the experimental trials. The effects of input variables on the performance and emission characteristics of the engine were thoroughly analyzed and comprehensively discussed as well. According to the experimental results, injection timing and engine load could significantly affect all the investigated performance and emission parameters. Water and nanoparticle addition to diesel could markedly affect some performance and emission parameters. The modeling system could predict the output parameters with an R2 > 0.93, MSE 
    Matched MeSH terms: Hydrocarbons
  17. Potent antibacterial activity of halogenated metabolites from Malaysian red algae, Laurencia majuscula (Rhodomelaceae, Ceramiales)
    Vairappan CS
    Biomol. Eng., 2003 Jul;20(4-6):255-9.
    PMID: 12919806
    Red algae genus Laurencia (Rhodomelaceae, Ceramiales) are known to produce a wide range of chemically interesting secondary halogenated metabolites. This investigation delves upon extraction, isolation, structural elucidation and antibacterial activity of inherently available secondary metabolites of Laurencia majuscula Harvey collected from two locations in waters of Sabah, Malaysia. Two major halogenated compounds, identified as elatol (1) and iso-obtusol (2) were isolated. Structures of these compounds were determined from their spectroscopic data such as IR, 1H-NMR, 13C-NMR and optical rotation. Antibacterial bioassay against human pathogenic bacteria was conducted using disc diffusion (Kirby-Bauer) method. Elatol (1) inhibited six species of bacteria, with significant antibacterial activities against Staphylococcus epidermis, Klebsiella pneumonia and Salmonella sp. while iso-obtusol (2) exhibited antibacterial activity against four bacterial species with significant activity against K. pneumonia and Salmonella sp. Elatol (1) showed equal and better antibacterial activity compared with tested commercial antibiotics while iso-obtusol (2) only equaled the potency of commercial antibiotics against K. pneumonia and Salmonella sp. Further tests conducted using dilution method showed both compounds as having bacteriostatic mode of action against the tested bacteria.
    Matched MeSH terms: Hydrocarbons, Halogenated/metabolism; Hydrocarbons, Halogenated/pharmacology*; Hydrocarbons, Halogenated/chemistry*
  18. Modulation of affinity of a marine pseudomonad for toluene and benzene by hydrocarbon exposure
    Law AT, Button DK
    Appl Environ Microbiol, 1986 Mar;51(3):469-76.
    PMID: 16347006
    Trace (microgram liter) quantities of either toluene or benzene injected into an amino-acid-limited continuous culture of Pseudomonas sp. strain T2 were utilized immediately with affinities of 2.6 and 6.8 liters g of cells h, respectively, and yielded large amounts of organic products, carbon dioxide, and cells. The immediate utilization of hydrocarbons by hydrocarbon-deprived organisms helps to establish the nutritional value of nonpolar substrates in the environment. The observation of small Michaelis constants for toluene transport led to tests of metabolic competition between hydrocarbons; however, competitive inhibition of toluene metabolism was not found for benzene, naphthalene, xylene, dodecane, or amino acids. Benzene and terpenes were inhibitory at milligram liter concentrations. Toluene was metabolized by a strongly inducible system when compared with benzene. The capacity of toluene to effect larger affinity values increased with exposure time and concentration. The kinetics of induction suggested saturation phenomena, resulting in an induction constant, K(ind), of 96 mug of toluene liter. Maximal induction of amino-acid-grown cells required about 80 h, with the affinity reaching 317 liters g of cells h.
    Matched MeSH terms: Hydrocarbons
  19. Fulltext Distribution of PAHs and n-alkanes in Klang river surface sediments, Malaysia
    Bakhtiari, Alireza Riyahi, Mohamad Pauzi Zakaria, Mohammad Ismail Yaziz, Mohamad Nordin Lajis, Bi, Xinhui, Mohamad Reza Mohamad Shafiee, et al.
    Pertanika Journal of Science & Technology, 2010;18(1):-.
    MyJurnal
    Surface sediment samples were collected from five locations at the downstream of Klang River in January 2007 to examine the spatial distribution, composition, and sources of 19 parent polycyclic aromatic hydrocarbons (PAHs) and aliphatic hydrocarbon (n-alkanes) using gas chromatographymass spectrometry. The total concentrations of the 19 PAHs in the sediments were found to range from 1304 to 2187 ng g-1 sediment. Meanwhile, total concentrations of n-alkanes ranged from 17008 to 27116 μg g-1 sediment. The concentration of n-alkanes in the sediment was significantly correlated (r = 0.991, p = 0.001) with the content of sediment organic carbon. In this study, all the sediments exhibited phenanthrene/anthracene (PHE/ANT >15) fluoranthene/(fluorantene+pyrene) (FLT/FLT+PYR < 0.4), ethylphenanthrenes/phenanthrene (MP/P >1), combustion PAHs/total PAHs (CombPAH/Σ19PAH
    Matched MeSH terms: Polycyclic Hydrocarbons, Aromatic
  20. Fulltext A thermodynamic equilibrium analysis on oxidation of methane to higher hydrocarbons
    Nor Aishah Saidina Amin, Soon, Ee Peng
    Pertanika Journal of Science & Technology, 2009;17(2):-.
    MyJurnal
    Thermodynamic chemical equilibrium analysis using, total Gibbs energy minimization method, was carried out for methane oxidation to higher hydrocarbons. For a large methane conversion and a high selectivity to higher hydrocarbons, the system temperature and oxygen concentration played a vital role, whereas, the system pressure only slightly influenced the two variables. Numerical results showed that the conversion of methane increased with the concentration of oxygen and reaction temperature, but it decreased with pressure. Nevertheless, the presence of oxygen suppressed the formation of higher hydrocarbons which mostly consisted of aromatics, but enhanced the formation of hydrogen. As the system pressure increased, the aromatics, olefins and hydrogen yields diminished, but the paraffin yield improved. Carbon monoxide seemed to be the major oxygen-containing equilibrium product from methane oxidation, whilst almost no H2O, CH3OH and HCOH were detected although traces amount of carbon dioxide were formed at relatively lower temperature and higher pressure. The total Gibbs energy minimization method is useful to theoretically analyze the feasibility of methane conversion to higher hydrocarbons and syngas at the selected temperature and pressure.
    Matched MeSH terms: Hydrocarbons
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