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101.
Mahmoud M.M. Abdel-Salam 《Journal of the Air & Waste Management Association (1995)》2013,63(8):956-962
Indoor particulate matter samples were collected in 17 homes in an urban area in Alexandria during the summer season. During air measurement in all selected homes, parallel outdoor air samples were taken in the balconies of the domestic residences. It was found that the mean indoor PM2.5 and PM10 (particulate matter with an aerodynamic diameter ≤2.5 and ≤10 μm, respectively) concentrations were 53.5 ± 15.2 and 77.2 ± 15.1 µg/m3, respectively. The corresponding mean outdoor levels were 66.2 ± 16.5 and 123.8 ± 32.1 µg/m3, respectively. PM2.5 concentrations accounted, on average, for 68.8 ± 12.8% of the total PM10 concentrations indoors, whereas PM2.5 contributed to 53.7 ± 4.9% of the total outdoor PM10 concentrations. The median indoor/outdoor mass concentration (I/O) ratios were 0.81 (range: 0.43–1.45) and 0.65 (range: 0.4–1.07) for PM2.5 and PM10, respectively. Only four homes were found with I/O ratios above 1, indicating significant contribution from indoor sources. Poor correlation was seen between the indoor PM10 and PM2.5 levels and the corresponding outdoor concentrations. PM10 levels were significantly correlated with PM2.5 loadings indoors and outdoors and this might be related to PM10 and PM2.5 originating from similar particulate matter emission sources. Smoking, cooking using gas stoves, and cleaning were the major indoor sources contributed to elevated indoor levels of PM10 and PM2.5.
Implications: The current study presents results of the first PM2.5 and PM10 study in homes located in the city of Alexandria, Egypt. Scarce data are available on indoor air quality in Egypt. Poor correlation was seen between the indoor and outdoor particulate matter concentrations. Indoor sources such as smoking, cooking, and cleaning were found to be the major contributors to elevated indoor levels of PM10 and PM2.5. 相似文献
102.
Thirty-four analogs with variable antifungal activity were selected to develop models for establishing three-dimensional quantitative structure-activity relationships (3D-QSAR). Comparative molecular field analysis (CoMFA) and comparative similarity indices analyses (CoMSIA) were conducted on the group of analogs to determine the structural requirements for selectivity and potency in inhibiting biofilm formation and fungal growth. The best CoMFA model predicted a q(2) = 0.5 and an r(2) = 0.991, and revealed that electrostatic properties play a significant role in potency and selectivity. The best CoMSIA model combined electrostatics, hydrogen bond acceptor and donor, and hydrophobic fields with a q(2) = 0.664 r(2) = 0.952, S = 0.099, and F = 139.892. The analyses of the contour maps from both models provide significant insight into the structural necessities for a potent compound. Therefore, manipulating various chemical properties of the substituted groups on the farnesol chain can be used to enhance the fungicidal properties of the target compound. 相似文献
103.
Recyclables recovery of europium and yttrium metals and some salts from spent fluorescent lamps 总被引:2,自引:0,他引:2
Rabah MA 《Waste management (New York, N.Y.)》2008,28(2):318-325
Europium and yttrium metals and some valuable salts were recovered from the powder coating the inner surface of the glass tubes of fluorescent lamps. The tubes were broken under 30% aqueous acetone to avoid emission of mercury vapor to the atmosphere, and the powder was collected by brushing. Metals available in the powder were pressure leached using sulfuric/nitric acid mixture. Sulphate salt of europium and yttrium so obtained was converted to thiocyanate. Trimethyl-benzylammonium chloride solvent was used to selectively extract Eu and Y from the thiocyanate solution. The metal loaded in the organic solvent was recovered by N-tributylphosphate in 1M nitric acid to produce nitrate salts of Eu and Y. Europium nitrate was separated from yttrium nitrate by dissolving in ethyl alcohol. The isolated powder contained 1.62% europium oxide, 1.65% yttrium oxide, 34.48% calcium sulphate, 61.52% Ca orthophosphate and 0.65% other impurity metals by weight. Autoclave digestion of the powder in the acid mixture for 4h at approximately 125 degrees C and 5 MPa dissolved 96.4% of the yttrium and 92.8% of the europium. Conversion of the sulphate to thiocyanate is favoured at low temperature. Extraction of Eu and Y from the thiocyanate solution attained its maximum at approximately 80 degrees C. N-tributylphosphate in 1N nitric acid at 125 degrees C achieved a stripping extent of 99%. Thermal reduction using hydrogen gas at 850 degrees C and 1575 degrees C produced europium and yttrium metals, respectively. A metal separation factor of 9.4 was achieved. Economic estimation revealed that the suggested method seemed feasible for industrial applications. 相似文献
104.
Abu-Allaban M Gillies JA Gertler AW Clayton R Proffitt D 《Environmental monitoring and assessment》2007,132(1-3):155-163
A source apportionment study was carried out to estimate the contribution of motor vehicles to ambient particulate matter
(PM) in selected urban areas in the USA. Measurements were performed at seven locations during the period September 7, 2000
through March 9, 2001. Measurements included integrated PM2.5 and PM10 concentrations and polycyclic aromatic hydrocarbons (PAHs). Ambient PM2.5 and PM10 were apportioned to their local sources using the chemical mass balance (CMB) receptor model and compared with results obtained
using scanning electron microscopy (SEM). Results indicate that PM2.5 components were mainly from combustion sources, including motor vehicles, and secondary species (nitrates and sulfates).
PM10 consisted mainly of geological material, in addition to emissions from combustion sources. The fractional contributions of
motor vehicles to ambient PM were estimated to be in the range from 20 to 76% and from 35 to 92% for PM2.5 and PM10, respectively. 相似文献
105.
Huda Mahmoud Redha Al-Hasan Majida Khanafer Samir Radwan 《Environmental science and pollution research international》2010,17(2):383-391
Background, aim, and scope
Due to the active production and transport of crude oil in the Arabian Gulf region, the Arabian Gulf coasts are routinely polluted with oil. Therefore, such coasts have been subject of studies aiming at assessing the roles of indigenous microbial consortia in cleaning these environments. In the present study, epilithic microbial communities along Kuwait coasts were studied for their oil degradation potential. 相似文献106.
Wazne M Jagupilla SC Moon DH Christodoulatos C Koutsospyros A 《Journal of environmental quality》2008,37(6):2125-2134
Batch leaching tests, qualitative and quantitative x-ray powder diffraction (XRPD) analyses, and geochemical modeling were used to investigate the leaching mechanisms of Cr(VI) from chromite ore processing residue (COPR) samples obtained from an urban area in Hudson County, New Jersey. The pH of the leaching solutions was adjusted to cover a wide range between 1 and 12.5. The concentration levels for total chromium (Cr) and Cr(VI) in the leaching solutions were virtually identical for pH values >5. For pH values <5, the concentration of total Cr exceeded that of Cr(VI) with the difference between the two attributed to Cr(III). Geochemical modeling results indicated that the solubility of Cr(VI) is controlled by Cr(VI)-hydrocalumite and Cr(VI)-ettringite at pH >10.5 and by adsorption at pH <8. However, experimental results suggested that Cr(VI) solubility is controlled partially by Cr(VI)-hydrocalumite at pH >10.5 and by hydrotalcites at pH >8 in addition to adsorption of anionic chromate species onto inherently present metal oxides and hydroxides at pH <8. As pH decreased to <10, most of the Cr(VI) bearing minerals become unstable and their dissolution contributes to the increase in Cr(VI) concentration in the leachate solution. At low pH ( <1.5), Cr(III) solid phases and the oxides responsible for Cr(VI) adsorption dissolve and release Cr(III) and Cr(VI) into solution. 相似文献
107.
Risk-based maintenance (RBM): a quantitative approach for maintenance/inspection scheduling and planning 总被引:3,自引:0,他引:3
Faisal I. Khan Mahmoud M. Haddara 《Journal of Loss Prevention in the Process Industries》2003,16(6):561-573
The overall objective of the maintenance process is to increase the profitability of the operation and optimize the total life cycle cost without compromising safety or environmental issues. Risk assessment integrates reliability with safety and environmental issues and therefore can be used as a decision tool for preventive maintenance planning. Maintenance planning based on risk analysis minimizes the probability of system failure and its consequences (related to safety, economic, and environment). It helps management in making correct decisions concerning investment in maintenance or related field. This will, in turn, result in better asset and capital utilization.
This paper presents a new methodology for risk-based maintenance. The proposed methodology is comprehensive and quantitative. It comprises three main modules: risk estimation module, risk evaluation module, and maintenance planning module. Details of the three modules are given. A case study, which exemplifies the use of methodology to a heating, ventilation and air-conditioning (HVAC) system, is also discussed. 相似文献
108.
Natalie A. Hamad Mahmoud M. El-Halwagi Nimir O. Elbashir Sam M. Mannan 《Journal of Loss Prevention in the Process Industries》2013,26(3):528-533
Fischer–Tropsch Synthesis (FTS) is a primary pathway for gas-to-liquid (GTL) technology. In order to overcome commercial problems associated with reaction and transport phenomena, the use of supercritical solvents has been proposed to enhance conversion, catalyst stability and improve temperature control in fixed-bed reactors. One of the major challenges in designing the supercritical FTS reactor unit is selecting appropriate solvents of critical properties within the required reaction operating conditions. Numerous alternatives exist and should be screened based on relevant criteria. The main aim of this paper is to develop a screening methodology to identify an optimum supercritical solvent or a mixture of solvents that meet the aforementioned criteria while minimizing the cost and more importantly satisfying the safety constraints. A safety metric system was developed in order to compare the risk issues associated with using different solvents. In addition, an economic analysis of using the different solvents was performed. Finally, a case study was solved to illustrate the use of the proposed metrics and the selection of solvents based on safety and techno-economic criteria. 相似文献
109.
110.
Nasser A. M. Barakat Moaaed Motlak Ahmed Taha M. M. Nassar M. S. Mahmoud H. Fouad 《International Journal of Green Energy》2016,13(7):642-649
In this study, the photocatalytic activity of TiO2 nanofibers toward ammonia borane hydrolysis has been strongly modified by doping the nanostructure by ZnO and Fe2O3 oxides. Due to the differences in the work function and band gap energy among the three semiconductors (TiO2, ZnO and Fe2O3), illumination of TiO2 leads to accumulate the electrons and holes on the conduction and valance bands of Fe2O3 and ZnO, respectively. Accordingly, the experimental results indicated that the surface of the obtained nanofibers is very active which results in an instant hydrolysis of ammonia borane molecules reaching the active zone surrounding the nanofibers. Moreover, negative activation energy was determined as increasing the temperature led to decrease the photocatalytic performance. Furthermore, kinetic studies indicated that the heterogeneous catalytic reaction describing the ammonia borane hydrolysis process is zero order which additionally supports the super activity of the introduced nanofibers. It was also observed that Fe2O3 content in the introduced nanofibers has distinct influence as the best performance was obtained at 1 wt%. The modified TiO2 nanofibers were prepared by calcination of electrospun nanofibers composed of titanium isopropoxide, zinc acetate and iron acetate in air at 700 °C for 1 h. Overall, the present study opens a new avenue to overcome the fast electrons/holes recombination dilemma facing TiO2-based nanostructures. 相似文献