排序方式: 共有28条查询结果,搜索用时 140 毫秒
1.
Meriem Fardioui Taoufik Guedira Abou El Kacem Qaiss Rachid Bouhfid 《Journal of Polymers and the Environment》2018,26(2):443-451
The aim of this paper was to study the effects of reinforcing low density polyethylene (LDPE) by using bio-fillers (Doum cellulose or Shrimp chitin) on the mechanical properties. Both, Doum cellulose extracted frsom Doum leaves and Shrimp chitin extracted from shrimp co-products were compounded with LPDE without and with compatibilizer. The biocomposites were prepared by melt blending in a twin-screw extruder. Torsion and flexural tests were performed to investigate the impact of each reinforcement on the biocomposite mechanical properties. The SEM was carried out to study the filler/polymer interface adhesion. The present study has demonstrated that Doum fibers and shrimp chitin succeed in improving the mechanical properties of LPDE bio-composites. The results also showed that the use of maleic anhydride-grafted polyethylene as a compatibilizer improves filler adhesion/matrix and mechanical properties. This study exhibits that polyethylene composites based on Doum fibers or shrimp chitin can be used to replace the polyethylene materials in several fields like packaging and automotive industries. 相似文献
2.
3.
ROUABHI Rachid DJEBAR-BERREBBAH H DJEBAR MR 《应用与环境生物学报》2006,12(4):514-517
Harmful bugs affect food production,directly by the qualitativeor quantitative reduction of the harvests,or indirectly while servinglike vectors of several illnesses of the plants and human[1].Many chemical products are used by human for a long time inthe… 相似文献
4.
Managing Mediterranean soil resources under global change: expected trends and mitigation strategies
Lagacherie Philippe Álvaro-Fuentes Jorge Annabi Mohamed Bernoux Martial Bouarfa Sami Douaoui Abdelkader Grünberger Olivier Hammani Ali Montanarella Luca Mrabet Rachid Sabir Mohammed Raclot Damien 《Regional Environmental Change》2018,18(3):663-675
Regional Environmental Change - The soils of the Mediterranean Basin are the products of soil processes that have been governed by a unique convergence of highly differentiated natural and... 相似文献
5.
Municipal solid waste incineration (MSWI) bottom ash is an atypical granular material because it may include industrial by-products that result from the incineration of domestic waste. The prospects for the beneficial use of this particular material mainly lie in the field of road construction, as a substitute for the traditional natural aggregates. However, its mechanical properties are still little known, particularly in term of stiffness and deformability, characteristics that are essential to the construction of a durable roadway. The purpose of this paper is to describe better the mechanical behaviour of this recycled material. In order to reach this objective, a large experimental campaign is presented. The first part of this paper presents and comments in detail on the results obtained from static monotonic tests. Oedometric and triaxial shear tests were performed on MSWI bottom ash both before and after treatment with a specific hydraulic binder. These tests allow specification of the mechanical characteristics of the MSWI bottom ash, such as the initial Young's modulus, Poisson's ratio, the compressibility index, the friction angle, and the contracting or dilating behaviour of the material. The results reveal a mechanical behaviour similar to that of initially dense standard materials (sands, unbound granular materials) and a dependence on the applied average pressure, characteristic of the mechanical behaviour of granular media. More laboratory data on other samples of MSWI bottom ash are required to ensure that this comparison is statistically valid. 相似文献
6.
7.
Spreading of oil on water in the surface-tension regime 总被引:1,自引:0,他引:1
Rachid Chebbi 《Environmental Fluid Mechanics》2014,14(6):1443-1455
The third stage of oil spreading on water, in which surface-tension force promotes spreading against the resisting viscous effect, is investigated using a similarity solution in combination with an integral boundary-layer technique to solve the unidirectional oil-spreading dynamics problem in the last stage of spreading. The thin layer is assumed to be supplied by oil from a bulk boundary. Using a constitutive equation for oil-film surface tension versus oil-film thickness, analytical solutions near the bulk boundary and near the edge are developed. Using the asymptotic solutions to initiate integration, the differential equations for the oil thickness, oil velocity, and boundary-layer profiles are integrated starting from the leading edge and bulk boundary, which after matching provide a complete solution. The results for the spreading-law prefactors are found to differ by about 10 % from published theoretical results using the same constitutive equation. Using an empirical constitutive equation for oil-film surface tension versus distance from the bulk boundary leads to a spreading-law prefactor that is in excellent agreement with the published experimental result and published theoretical work providing and using the same empirical constitutive equation. 相似文献
8.
Wafa Kharroubi Madiha Dhibi Manel Mekni Zohra Haouas Imed Chreif Fadoua Neffati Mohamed Hammami Rachid Sakly 《Environmental science and pollution research international》2014,21(20):12040-12049
Six groups of rats (n?=?10 per group) were exposed to 1 and 10 mg/l of sodium arsenate for 45 and 90 days. Kidneys from treated groups exposed to arsenic showed higher levels of trans isomers of oleic and linoleic acids as trans C181n-9, trans C18:1n-11, and trans C18:2n-6 isomers. However, a significant decrease in eicosenoic (C20:1n-9) and arachidonic (C20:4n-6) acids were observed in treated rats. Moreover, the “Δ5 desaturase index” and the saturated/polyunsaturated fatty acids ratio were increased. There was a significant increase in the level of malondialdehyde at 10 mg/l of treatment and in the amount of conjugated dienes after 90 days (p?0.05). Significant kidney damage was observed at 10 mg/l by increase of plasma marker enzymes. Histological studies on the ultrastructure changes of kidney supported the toxic effect of arsenate exposure. Arsenate intoxication activates significantly the superoxide dismutase at 10 mg/l for 90 days, whereas the catalase activity was markedly inhibited in all treated groups (p?0.05). In addition, glutathione peroxidase activity was significantly increased at 45 days and dramatically declined after 90 days at 10 mg/l (p?0.05). A significant increase in the level of glutathione was marked for the groups treated for 45 and 90 days at 1 mg/l followed by a significant decrease for rats exposed to 10 mg/l for 90 days. An increase in the level of protein carbonyl was observed in all treated groups (p?0.05). In conclusion, the present study provides evidence for a direct effect of arsenate on fatty acid (FA) metabolism which concerns the synthesis pathway of n-6 polyunsaturated fatty acids and leads to an increase in the trans FAs isomers. Therefore, FA-induced arsenate kidney damage could contribute to trigger kidney cancer. 相似文献
9.
Meriem Fardioui Abdelhamid Stambouli Taoufik Gueddira Abdelouahed Dahrouch Abou El Kacem Qaiss Rachid Bouhfid 《Journal of Polymers and the Environment》2016,24(4):356-362
The aim of this investigation was to extract nanocrystalline cellulose (NCC) from Moroccan Doum fibers (Chamaerops humilis) by chemical treatment to examine their potential for use as reinforcement fibers in bionanocomposite applications. The chemical composition, morphological and structural properties of the Doum fibers was determined at different stages of chemical treatment. Morphological (transmission electron microscopy and scanning electron microscopy), structural characterization (X-ray diffraction, Fourier transformed infrared), thermal characterization (thermogravimetric analysis). The suspension electrostatic stabilization (zeta potential) of NCCs was also carried out. The results of these characterization analysis found that average size of the NCC is 220 nm in length and 11 nm in diameter, with high crystallinity index (93 %), a thermal stability comparable to that of untreated Doum fibers (degradation temperature 340 °C), which is reasonably promising for the use of these nanofibers in reinforced-polymer manufacturing, and a good stability in water suspension that it allows their utilization such as reinforcement of the water-soluble polymers to prepare the bio-nanocomposite. 相似文献
10.
In the event of an accidental atmospheric release of radionuclides from a nuclear power plant, accurate real-time forecasting of the activity concentrations of radionuclides is acutely required by the decision makers for the preparation of adequate countermeasures. Yet, the accuracy of the forecasted plume is highly dependent on the source term estimation. Inverse modelling and data assimilation techniques should help in that respect. However the plume can locally be thin and could avoid a significant part of the radiological monitoring network surrounding the plant. Deploying mobile measuring stations following the accident could help to improve the source term estimation. In this paper, a method is proposed for the sequential reconstruction of the plume, by coupling a sequential data assimilation algorithm based on inverse modelling with an observation targeting strategy. The targeting design strategy consists in seeking the optimal locations of the mobile monitors at time t + 1 based on all available observations up to time t.The performance of the sequential assimilation with and without targeting of observations has been assessed in a realistic framework. It focuses on the Bugey nuclear power plant (France) and its surroundings within 50 km from the plant. The existing surveillance network is used and realistic observational errors are assumed. The targeting scheme leads to a better estimation of the source term as well as the activity concentrations in the domain. The mobile stations tend to be deployed along plume contours, where activity concentration gradients are important. It is shown that the information carried by the targeted observations is very significant, as compared to the information content of fixed observations. A simple test on the impact of model error from meteorology shows that the targeting strategy is still very useful in a more uncertain context. 相似文献