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641.
Mohamed Cissé Didier Montet Gérard Loiseau Marie-Noëlle Ducamp-Collin 《Journal of Polymers and the Environment》2012,20(3):830-837
The individual and interactive effects of glycerol and chitosan concentrations on edible film properties were investigated using response surface methodology. The results of ANOVA indicated that all the independent variables exhibited significant effect on the film properties. Chitosan concentration had a positive effect on CO2 permeability and negative effect on O2 while the glycerol concentration had a positive effect on permeability to both gases. Regarding water vapor permeability, the chitosan concentration had a negative effect, whereas the glycerol had no influence. Moreover, both chitosan and glycerol concentration influenced the elongation at break point (%A), and only glycerol concentration had a significant effect on tensile strength. Optimization by desirability approach was carried out on the independent variables to get the optimum levels within the experimental conditions. It was found that 1.5 % of chitosan and 25 % of glycerol (wt/wt of chitosan) retarded respiration and showed a strong permeability to water vapor. 相似文献
642.
W. O. Wan Nadirah M. Jawaid Abeer A. Al Masri H. P. S. Abdul Khalil S. S. Suhaily A. R. Mohamed 《Journal of Polymers and the Environment》2012,20(2):404-411
A study on chemical, morphology, and thermal analysis of cultivated pineapple leaf fibres (PALF) were carried out. The chemical compositions were determined by using Technical Association Pulp and Paper Industries standards. Fourier Transform-Infrared Spectroscopy analysis of PALF detect sharp band at 1,733?cm?1, due to the absorption of carbonyl stretching of ester and carboxyl groups which is most abundant in pineapple leaf hemicelluloses. Cell wall ultra structure of PALF was studied by using Transmission electron microscopy. Transmission electron micrograph confirmed that cell wall structure of PALF consists of middle lamella, primary wall and secondary wall including S1, S2 and S3 layers. X-Ray Diffraction indicated that PALF have crystalline nature. Thermal analysis of PALF shows that T10% and T50% weight loss occurred at temperature of 212 and 306?°C respectively. Differential Scanning Calorimetry of PALF showed the broad endothermic peak at a temperature of 80?°C. The relationships between these properties were discussed and relate it with industrial application of pineapple leaf fibers. 相似文献
643.
The photolysis of the N methyl carbamate pesticide oxamyl (Z isomer) has been studied in aqueous solution. Continuous irradiation at mainly λ = 254 and λ > 290 nm has been performed to characterise the pesticide photochemical behaviour in water at pH = 6.0. Upon monochromatic irradiation, the phototransformation quantum yield was evaluated to be roughly constant, with a value of 0.54 ± 0.08. Upon polychromatic irradiation, a photochemical efficiency has been estimated to be 0.5 ± 0.1 by using phenol as a reference compound. Two main degradation products were identified: the isomer (E) of oxamyl and the nitrile derivative (N,N-dimethyl-2-nitrilo-acetamide). The photolysis of the oximino derivative, an hydrolysis product of oxamyl, was also studied. Upon irradiation at 254 nm, the quantum yield of phototransformation was found to be 0.28. A unique photoproduct was detected: it corresponds to the (E) isomer of the oximino derivative. For prolonged irradiations, a photostationary state was reached between the oximino and its (E) isomer. From kinetics data, the removal of oxamyl and of the oximino derivative during a UV disinfection step used in drinking water production was calculated to be 45 and 13%, respectively. 相似文献
644.
Amer HA Shawky S Hussein MI Abd el-Hady ML 《Journal of environmental monitoring : JEM》2002,4(4):583-587
Coal is largely composed of organic matter, but it is the inorganic matter in coal minerals and trace elements that have been cited as possible causes of health, environmental and technological problems associated with the use of coal. Some trace elements in coal are naturally radioactive. These radioactive elements include uranium (U), thorium (Th) and their numerous decay products, including radium (Ra) and radon (Rn). Although these elements are less chemically toxic than other coal constituents, such as arsenic, selenium or mercury, questions have been raised concerning the possible risk from radiation. In order to accurately address these questions and to predict the mobility of radioactive elements during the coal fuel cycle, it is important to determine the specific activity, distribution and form of radioactive elements in coal. The assessment of the radiation exposure from coal burning is critically dependent on the specific activity of radioactive elements in coal and in the fly ash that remains after combustion. The El-Maghara coal mine is the only producing coal mine in Egypt. It is located in the middle of the Sinai desert about 250 km north-east of Cairo, where a coal-fired power plant is intended to be built. In this study, a pre-operational radiological baseline of the site and the occupational radiation exposures due to radon progeny in the mine were determined. The specific activities of 226Ra, 232Th and 40K in soil and coal dust samples collected along the main gallery ranges were found to be 6-22.9, 9.6-47.3 and 77-489 Bq kg-1, respectively. Soil samples collected around the mine showed concentrations of 226Ra, 232Th and 40K in the ranges 2.7-20.2, 3.2-12.6 and 14.6-201 Bq kg-1, respectively. All of the mean values of radon progeny were lower than the action levels for working places recommended in the International Commission on Radiological Protection (ICRP) 65. 相似文献
645.
Natural radionuclides, such as (210)Po and (210)Pb were measured in the water samples collected from six stations at Kuala Selangor, Malaysia. Results for (210)Po and (210)Pb in dissolved and particulate phases have showed the difference in distribution and chemical behavior. The fluctuation activities of (210)Po and (210)Pb depend on wave action, geology and degree of fresh water input occurring at study areas and probably due to different sampling dates. The distribution coefficient, K(d), values of (210)Po and (210)Pb ranged from 2.0 x 10(3)lg(-1) to 265.15 x 10(5)lg(-1), and from 3.0 x 10(3)lg(-1) to 558.16 x 10(5)lg(-1), respectively. High K(d) values of (210)Po and (210)Pb indicated that a strong adsorption of (210)Po and (210)Pb onto suspended particles, and the sinking of both nuclides on the seabed at study locations were controlled by the characteristics of suspended particles. 相似文献
646.
Under the Egyptian program for radiation safety and control, airborne radioactivity measurements and radiological dose assessment were conducted in some phosphate and uranium mines. Abu-Tartor mine is one of the biggest underground phosphate mines in Egypt. Airborne radioactivity, radon ((222)Rn) and its short-lived decay products (progenies) and thoron ((220)Rn), were measured in selected locations along the mine. The environmental gamma and workers dose equivalent rate (mSv/y) were measured inside and outside the mine using thermo-luminescence dosimeters (TLD). The results were presented and discussed. The calculated annual effective dose due to airborne radioactivity is the main source of occupational exposure and exceeding the maximum recommended level by ICRP-60 inside the mine tunnels. A number of recommendations are suggested to control the occupational exposures. 相似文献
647.
Shaalan EA Canyon D Younes MW Abdel-Wahab H Mansour AH 《Environment international》2005,31(8):618-1166
Identification of novel effective mosquitocidal compounds is essential to combat increasing resistance rates, concern for the environment and food safety, the unacceptability of many organophosphates and organochlorines and the high cost of synthetic pyrethroids. An increasing number of researchers are reconsidering botanicals containing active phytochemicals in their efforts to address some of these problems. To be highly competitive and effective, the ideal phytochemical should possess a combination of toxic effects and residual capacity. Acute toxicity is required at doses comparable to some commercial synthetic insecticides while chronic or sub-chronic toxicity is required to produce growth inhibition, developmental toxicity and generational effects. In this article, we review the current state of knowledge on larvicidal plant species, extraction processes, growth and reproduction inhibiting phytochemicals, botanical ovicides, synergistic, additive and antagonistic joint action effects of mixtures, residual capacity, effects on non-target organisms, resistance, screening methodologies, and discuss promising advances made in phytochemical research. 相似文献
648.
649.
Megat Hanafiah Megat Ahmad Kamal Wan Mat Khalir Wan Khaima Azir MohamedKasmawati Zakaria Haslizaidi Wan Ngah Wan Saime 《环境科学学报(英文版)》2010,22(2):248-256
Rubber leaf powder (an agricultural waste) was treated with potassium permanganate followed by sodium carbonate and its
performance in the removal of Pb(II) ions from aqueous solution was evaluated. The interactions between Pb(II) ions and functional
groups on the adsorbent surface were confirmed by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy
(SEM) coupled with X-ray energy dispersive spectroscopy (EDX). The effects of several important parameters which can affect
adsorption capacity such as pH, adsorbent dosage, initial lead concentration and contact time were studied. The optimum pH range
for lead adsorption was 4–5. Even at very low adsorbent dosage of 0.02 g, almost 100% of Pb(II) ions (23 mg/L) could be removed.
The adsorption capacity was also dependent on lead concentration and contact time, and relatively a short period of time (60–90
min) was required to reach equilibrium. The equilibrium data were analyzed with Langmuir, Freundlich and Dubinin-Radushkevich
isotherms. Based on Langmuir model, the maximum adsorption capacity of lead was 95.3 mg/g. Three kinetic models including pseudo
first-order, pseudo second-order and Boyd were used to analyze the lead adsorption process, and the results showed that the pseudo
second-order fitted well with correlation coefficients greater than 0.99. 相似文献
650.
GIS and remote sensing as tools for conducting geo-hazards risk assessment along Gulf of Aqaba coastal zone,Egypt 总被引:2,自引:0,他引:2
Satellite remote sensing data, in addition to Geographic Information Systems (GIS), offers an excellent alternative to conventional
mapping techniques in monitoring and mapping of geo-hazards areas. One of the most sustainable development projects in Egypt
has been accomplished in Sinai, especially along and around the Gulf of Aqaba and the Gulf of Suez. Variations along the coastal
zone of the Gulf of Aqaba have been identified through the analysis of multi-temporal satellite images with the aid of GIS
analysis. The study area is subject to rapid and increasing changes in land-use/land-cover that resulting from natural and
human activities such as flash flooding, seismic activity, landslides, and tourist and urban activities. This is in addition
to the construction projects of roads, ports, PowerStation stations, mineral exploration, beaches, and tourist villages resulting
from major environmental impacts. The current study aims to use Remote Sensing and GIS tools to investigate, monitor, and
assess geo-hazards through the building of a geographical database. Several techniques have been developed over the last decade
mostly to study the geological and geomorphologic characteristics of the terrain; land-use and land-cover changes. These are
based on satellite imagery and Digital Elevation Models (DEM) to determine the topographic features, and geo-hazards maps.
It is concluded that integrated approaches to monitoring can successfully be used to assess the environmental impacts along
the Gulf of Aqaba coastal zone. 相似文献