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排序方式: 共有295条查询结果,搜索用时 15 毫秒
21.
ABSTRACTThe levels of 15 + 1 EU priority polycyclic aromatic hydrocarbons (15 + 1 EU PAHs) have been determined in different edible oils (extra virgin olive oil, virgin olive oil, sunflower oil, corn oil, and soybean oil) available in the Syrian market. The samples have been prepared by donor–acceptor complex chromatography and subsequently characterized by high-pressure liquid chromatography coupled with fluorescence and ultraviolet detection for quantification purposes. Variable levels of contamination have been found within different kinds of edible oil samples, and only chrysene has been detected in all the studied samples. Moreover, the mean total sum of 15 + 1 EU PAHs has shown variation from 29.8 µg/kg (corn oil) to 63.7 µg/kg (virgin olive oil). A total of 11 samples out of 38 samples (28.9%) have not fulfilled the European Union (EU) food law requirements. Nine samples have exceeded the EU legislation limit of benzo[a]pyrene (BaP) (2 µg/kg) and only two samples have exceeded the EU legislation limit of PAH4 (10 µg/kg) and had acceptable level of BaP. Finally, the mean and maximum dietary exposures of PAHs through consumption of edible oils have been estimated. 相似文献
22.
The Fukushima nuclear accident in Japan has renewed debates on the safety of nuclear power, possibly hurting the role of nuclear power in efforts to limit CO2 emissions. I develop a dynamic economy-wide model of Taiwan with a detailed set of technology options in the power sector to examine the implications of adopting different carbon and nuclear power policies on CO2 emissions and the economy. Without a carbon mitigation policy, limiting nuclear power has a small economic cost for Taiwan, but CO2 emissions may increase by around 4.5% by 2050 when nuclear is replaced by fossil-based generation. With a low-carbon target of a 50% reduction from year 2000 levels by 2050, the costs of cutting CO2 emissions are greatly reduced if both carbon sequestration and nuclear expansion were viable. This study finds that converting Taiwan's industrial structure into a less energy-intensive one is crucial to carry out the non-nuclear and low-carbon environment. 相似文献
23.
An automated software, BMAC, for modeling and performing the neutronics calculations of MNSRs and similar reactors (TRIGAs) has been developed. Calculation of initial excess reactivity, flux and power distributions, and all other neutronic parameters of the reactor, full core representation, can be made automatically using a 3-D model, by coupling WIMSD-4 and CITATION codes, in a very quick and simple way. No preliminary CITATION input file is needed. All required data are read from an external input file simply prepared. Accurate results for the parameters of the reactor, in the framework of Diffusion Theory, can be obtained. 相似文献
24.
M.Kassem 《金属学报(英文版)》2014,(1):180-184
A series of CuO-K2Mo4O13composite materials have been prepared by mixing appropriates quantities,in solid state,of CuO and pure K2Mo4O13 according to the molar ratios CuO/K2Mo4O13 = 0.05,0.1,0.2,0.5,and 1.The prepared samples were characterized using techniques such as X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),differential thermal analysis(DTA),nitrogen adsorption measurements,and UV spectroscopy.According to XRD results,the phase composition of the CuO-K2Mo4O13 systems has significantly changed by increasing the molar ratio CuO/K2Mo4O13 where new phases,identified as K2Mo3O10 and CuMoO4,have been detected.The formation of these new phases has been tracked through FT-IR and DTA measurements.The nitrogen adsorption-desorption measurements also reveal a change in the pore type of me studied materials due to the presence of these new phases.The photocatalytic activities of K2Mo4O13 and CuO-K2Mo4O13 composites were studied by means of monitoring the ability of these materials to the degradation,under UV irradiation,of methyl red in liquid media.It was found that the phase composition of the used samples significantly controls their photocatalytic activities. 相似文献
25.
A Decision Support System to Manage the Groundwater of the Zeuss Koutine Aquifer Using the WEAP-MODFLOW Framework 总被引:1,自引:0,他引:1
R. Hadded I. Nouiri O. Alshihabi J. Maßmann M. Huber A. Laghouane H. Yahiaoui J. Tarhouni 《Water Resources Management》2013,27(7):1981-2000
This paper describes the development of a Decision Support System (DSS) for groundwater management of the ‘Zeuss Koutine’ aquifer in southeastern Tunisia using the WEAP-MODFLOW framework. First, a monthly MODFLOW model was developed to simulate the behaviour of the studied aquifer. A conceptual model of the study area was designed and a WEAP schematic representing the real hydraulic system was developed. In addition to the studied aquifer, other water resources available in the region, such as desalination plants and groundwater, were taken into consideration in this DSS. Inputs to the hydrogeological model include natural recharge and inflow from higher neighbouring aquifers. Outputs are mainly agricultural, touristic and urban water consumption. It was shown that the DSS developed was able to evaluate water management scenarios up to 2030, especially future water consumption, transmission link flow and active cell heads of the MODFLOW model for each time step. Results for the Zeuss Koutine aquifer demonstrated that desalination plants already built in the cities of Jerba and Zarzis have contributed to decreasing the continuous drawdown observed before 1999. The use of a sea water desalination plant to supply Jerba and Zarzis in the future is a solution for reducing the Zeuss Koutine aquifer drawdown. Defining its optimal capacity over time poses a new research question. 相似文献
26.
A model is presented for p–n hetero-junction solar cells in which interface recombination is the dominant diode current transport mechanism. The model explains the large diode ideality factor (n>2) and the increased saturation current density in terms of increased density of interface states Nir. Furthermore, the model allows us to explain the non-translation between illuminated and dark J–V characteristics. The explanation is based on the assumption that, for high interface state density values, both the depletion layer width and the diffusion voltage in the p- and n-side of the junction are functions of Nir. The interface recombination leads to lower values of the open-circuit voltage, short-circuit current density, and fill factor. These results are illustrated by numerical calculations of solar cell parameters and compared with experimental data achieved for ZnO/CdS/CuGaSe2 single-crystal solar cells. 相似文献
27.
28.
Siba Hassan Richard L. Thomas Amin Shaban Issam Kawass Mohamad Khawlie 《Lakes & Reservoirs: Research and Management》2005,10(2):109-116
In order to assess the quality of the waters of the El‐Kabir River, which forms the border between Lebanon and Syria, water samples were collected for phosphorus (P) and nitrogen analyses at 39 sample stations in the river watershed (18 in Syria, 21 in Lebanon). These samples were collected on the main stem and three major tributaries (Nahr al‐Arous and Nahr Nasrive in Syria, Chadra River in Lebanon). Three major springs also were sampled. The sampling was carried out in September 2001, and January, April and August 2002. Nutrient analyses were carried out on samples taken in September 2001, January and April 2002 in Syria, and in September 2001 and August 2002 in Lebanon. The P concentrations were extremely high throughout the watershed, as were the ammonia‐nitrogen and nitrate‐nitrogen concentrations, indicating extensive pollution. Although the nitrite‐nitrogen concentration was relatively low, it is at the upper end of what might be considered normal, thereby perhaps being indicative of some anthropogenic sources. The spring waters were found to be polluted by nutrients. The nutrient sources contributing to the river pollution were mainly from piped, direct sewage discharges from the many settlements throughout the basin. These were supplemented by diffuse sources directly from agricultural fertilizer use and from the indiscriminate disposal of solid wastes into the river and on the stream banks and lands adjacent to the roads of the watershed. 相似文献
29.
Mohamad Khawlie Amin Shaban Chadi Abdallah T. Darwish Issam Kawass 《Lakes & Reservoirs: Research and Management》2005,10(2):85-92
Integrated watershed assessment, especially relying on remote sensing (RS), is a newly established procedure in developing countries. It is proving to be a major component in river‐basin environmental management. The recurrence of environmental problems in the Akkar El Kabir River watershed, as well as the lack of proper data on sources and sinks of pollutants, and the extent of human interference, led to the current study. Advanced geoinformation tools, such as RS and geographical information systems (GIS), prove to be a valuable asset in securing data on the fabric of the Akkar watershed in relation to its natural setting and anthropic interference. This is particularly true in the current study as the river constitutes the boundary between Lebanon and Syria. Remote sensing captures the watershed characteristics and land use on both sides without constraints. The natural fabric includes geology, drainage, hydrogeology, forest and soil. The anthropic fabric includes settlements, utilities, roads, agriculture and land use. If it were not for geoinformation techniques, the task of securing such data would be difficult. Also, these techniques show the impact of malpractices from excessive human interference that result in degradation of land and water quality. Changes in the watershed, such as environmental deterioration, are observed as water pollution, soil erosion, forest decline and socioeconomic imbalance. Obviously, this is the outcome of malpractices in a multisectorial system. A major challenge for RS and GIS is to quantify, model and predict, if possible, the extent of these changes. Remote sensing inherently captures the impact of interaction between nature and human beings. Detection of change is a major indicator that RS can contribute to the evaluation of the state of the environment. The application of it on this watershed reveals that significant changes have occurred over the last 10–15 years, most of which are anthropic. 相似文献
30.
Both wind energy potential and the electricity that could be generated by the wind for the Syrian land have been evaluated. An appropriate computer program was especially prepared and designed to perform the required calculations, mainly the wind energy potential and the generated electricity, using the available meteorological data provided by the Syrian Atlas. The program is capable of processing the wind data for any specific area, that is of course, in accordance with the needed requirements in fields of researches and applications.Moreover, calculations show that a huge energy potential is available for direct exploitation and as much as twice the current electricity consumption in Syria can be generated by the wind resource. 相似文献