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141.
The aim of this study was to evaluate the usefulness of oxidative stress biomarkers of pollution in native mussels Mytilus edulis chilensis from the Beagle Channel. Spatial and seasonal variations of catalase, glutathione-S-transferase and lipid peroxidation in gills and digestive gland were analyzed in relation to environmental parameters, heavy metals in sediment and in tissue. Four sites with anthropogenic impact and a control site were selected and monitored during the four seasons of 2007. We found significant differences among sites in concentrations of dissolved nutrients and heavy metals in sediments, with the highest values recorded at sites with anthropogenic pressure. Different patterns were observed between concentrations of metals in tissues and in sediments suggesting differences in bioavailability. There were also significant differences in biomarker responses among sites, despite the strong seasonal variability. Our results showed relatively moderate levels of pollution in the study area as a result of urban influences. 相似文献
142.
The survey of climatic drought trend in Iran 总被引:5,自引:3,他引:2
Hossein Bari Abarghouei Mohammad Amin Asadi Zarch Mohammad Taghi Dastorani Mohammad Reza Kousari Mehdi Safari Zarch 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(6):851-863
Drought is one of the most important natural hazards in Iran. Therefore, drought monitoring has become a point of concern
for most of the researchers. In the present study, the changes and trend of drought was surveyed, under the current global
climate changes, by non parametric Mann–Kendall statistical test for 42 synoptic stations at different places of Iran. Standardized
Precipitation Index (SPI) was calculated to recognize the drought condition at different time scales (3, 6, 9, 12, 18 and
24 months’ time series) for analyzing the drought trend in the recent 30 years. The obtained results have indicated a significant
negative trend of drought in many parts of Iran, especially the South-East, West and South-West regions of the country. According
to the results, although some parts of Iran such as North (around the Caspian Sea) and Northeast show no significant trend
but in other parts of country, the severity of drought has increased during the last 30 years. 相似文献
143.
An investigation of the Iranian climatic changes by considering the precipitation, temperature, and relative humidity parameters 总被引:5,自引:2,他引:3
Mohammad Reza Kousari Mohammad Reza Ekhtesasi Mehdi Tazeh Mohammad Ali Saremi Naeini Mohammad Amin Asadi Zarch 《Theoretical and Applied Climatology》2011,103(3-4):321-335
The present study tends to describe the survey of climatic changes in the case of the eastern and central areas of Iran and, to some extent, the northern parts. The monthly and yearly change trends in the minimum, maximum and mean temperatures, relative humidity, and the precipitation were surveyed for 26 synoptic stations in Iran during a 55-year period. The study was carried out by using the ??-Kendall test. The results showed the same temperature changes for the centrally located stations as the eastern and northern ones. Most of the stations in Zagros showed no significant temperature changes. A significant decrease in the precipitation was seen in summer in different stations. Most of the eastern and centrally located stations showed a decrease in relative humidity trend, while this condition was not recorded in Zagros and northern part of Iran. The present results also showed that the upward trend of minimum air temperature had an effect in increasing the mean air temperature in the stations with temperature ascending trend. This effect of minimum temperature was significantly more than that of the maximum temperature, which could be the result of increasing the amount of greenhouse gases and the reflection of received thermal energies, from land through the night. This increase in the temperature and a decrease in relative humidity would cause an increase in the evaporation of the received precipitation. 相似文献
144.
Mohamed Bakillah Steve Liang Amin Mobasheri Jamal Jokar Arsanjani Alexander Zipf 《International journal of geographical information science》2014,28(9):1940-1963
Data on population at building level is required for various purposes. However, to protect privacy, government population data is aggregated. Population estimates at finer scales can be obtained through areal interpolation, a process where data from a first spatial unit system is transferred to another system. Areal interpolation can be conducted with ancillary data that guide the redistribution of population. For population estimation at the building level, common ancillary data include three-dimensional data on buildings, obtained through costly processes such as LiDAR. Meanwhile, volunteered geographic information (VGI) is emerging as a new category of data and is already used for purposes related to urban management. The objective of this paper is to present an alternative approach for building level areal interpolation that uses VGI as ancillary data. The proposed method integrates existing interpolation techniques, i.e., multi-class dasymetric mapping and interpolation by surface volume integration; data on building footprints and points-of-interest (POIs) extracted from OpenStreetMap (OSM) are used to refine population estimates at building level. A case study was conducted for the city of Hamburg and the results were compared using different types of POIs. The results suggest that VGI can be used to accurately estimate population distribution, but that further research is needed to understand how POIs can reveal population distribution patterns. 相似文献
145.
Sulaiman Alaabed Abdel Monem Soltan Osman Abdelghany Bahaa Eldin Mahmoud Amin Mohamed El Tokhi Abbas Khaleel Abdullah Musalim 《Mineralogy and Petrology》2014,108(6):837-852
The thermal behavior of selected limestones from representative localities of the United Arab Emirates is investigated for their suitability for soft-burnt lime production. The limestone samples were collected from the Ghalilah, Musandam, Shauiba, Muthaymimah, Dammam and Asmari formations. The samples were characterized for petrography, mineral and chemical composition, together with physico-mechanical characteristics. Investigative methods included transmitted light microscopy (TLM), cathodoluminescence (CLM) and scanning electron microscopy (SEM), as well as X-ray micro-tomography (μ-CT), XRD, XRF and Archimedes method. The limestone samples were fired in an electrical muffle furnace for 0.25, 0.5, 1 and 2 hours at 800, 900, 1,000 and 1,100 °C. After firing the lime grains were tested to determine their hydration rate and microfabric. The Ghalilah and Musandam limes show the lowest and highest maximum hydration rates, respectively, due mainly to the impure nature of the former, and the smaller lime crystallites and dominance of post-calcination micro-cracks of the latter. The Dammam and Asmari limes preserve a “ghost” microfabric of the original limestone. Higher allochem contents impose lower activation energy requirements for calcination, which implies earlier calcination of the allochems. The Musandam, Shauiba and Muthaymimah limestones may be useful for the production of reactive soft-burnt lime under the applied firing conditions, however, the Dammam and Asmari limestones need more advanced calcination conditions than the applied ones. The Ghalilah limestone was found to be unsuitable for the production of lime. 相似文献
146.
A modification to the nonlinear Pastor–Zienkiewicz–Chan (PZC) constitutive model without any change in the number of model parameters is introduced in order to simulate stiffness degradation of dense sands at dynamic loading. The PZC model is based on generalized plasticity and was verified by good prediction of liquefaction and undrained behavior of saturated sand. The PZC is a robust model that can predict drained dynamic behavior of sands, especially stiffness increase in loose sand at reloading of dynamic loading. Yet, this model does not show stiffness degradation of dense sand at reloading. The modification is made through modifying the stress memory factor, H DM, which is multiplied by the plastic modulus, H L. This modification does not influence reloading behavior of loose sand. The modified PZC model is verified via results of drained cyclic tests. Two cyclic triaxial tests on loose and dense specimens, along with two cyclic plane strain tests on dense sand are utilized for validation. The model simulation shows that the modified PZC model is able to predict the stiffness degradation of dense sand at reloading well. 相似文献
147.
Magdy Y. Amin 《Astrophysics and Space Science》2003,284(4):1143-1157
A chemical evolution of W3 IRS5 have been studied during J-type shock. We modified our code of for one-dimensional J-type
shock to satisfy the physical conditions of W3 IRS5. The chemical rate equations and the hydrodynamics of shocks are integrated
simultaneously. We find that, a shock of speed V
s = 10 km s-1 and magnetic induction B=4.1×10-6 Gauss, propagate into molecular gas density of n=104cm-3, and with initial temperature of 30 K (pre shock) satisfy the physical conditions of W3 IRS5. The results using the extensive
chemical network with the most updating reaction rates show that the calculated fractional abundances are in agreement with
observation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
148.
149.
M. Y. Amin 《Earth, Moon, and Planets》1996,73(2):133-145
A new time-dependent model of chlorine chemistry in cold and warm TMC-1 and Orion clouds was constructed using results of recent laboratory and theoretical studies on the reaction of chlorine molecules. The chemistry of chlorine was found to be fairly simple in dense interstellar clouds. Only the species Cl and HCl have a significant fractional abundance. Our results for the HCl molecule are in agreement with those obtained from the observation and from theoretical values of Orion cloud. 相似文献
150.
D. A. Kamel H. A. Farag N. K. Amin Y. O. Fouad 《International Journal of Environmental Science and Technology》2017,14(4):785-794
The need for renewable environmentally friendly energy resources is growing every day. Biodiesel is one of the most promising alternatives to the conventional non-renewable energy resources. Heterogeneous catalysts proved a high efficiency in the transesterification of oils to produce biodiesel. In this research, activated carbon was tested as a heterogeneous catalyst in the transesterification of two non-edible oils (waste cooking oil and Jatropha oil) with methanol to produce biodiesel. Activated carbon was characterized using X-ray diffraction, scanning electron microscope and Fourier transformed infrared. The effect of different operating parameters, namely operation time (30, 60, 120 and 180 min), alcohol-to-oil molar ratio (4:1, 6:1, 8:1 and 10:1), catalyst loading [0.5, 1, 2, 3 and 5% (w/w)] and rotational speed (100, 200, 300 and 400 rpm), was investigated. Results showed that increasing the operational time, the alcohol-to-oil molar ratio and the catalyst loading increases the conversion to biodiesel but only to some extent; increasing the stirring rate was found to be beneficial to the process. The optimum conditions were found to be 2 h of heating, 6:1 alcohol-to-oil ratio, 1 wt% catalyst loading and 400 rpm stirring. Under optimum conditions, the conversion to biodiesel reached 93.95 and 93.27% for the waste cooking oil and the Jatropha oil, respectively. The properties of the obtained biodiesel (density, viscosity, flash point, pour point and cloud point) were measured giving promising results. 相似文献