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71.
Atousa Assadihaghi Stéphane Bila Dominique Baillargeat Michel Aubourg Serge Verdeyme Christelle Boichon Jérôme Puech Luc Lapierre 《国际射频与微波计算机辅助工程杂志》2008,18(5):454-463
Topology optimization can be seen as optimizing a distribution of small topological elements within a domain with respect to given specifications. A numerical topology gradient (TG) algorithm is applied in the context of electromagnetism for optimizing microwave devices, computing the sensitivity on adding or removing small metallic elements. This method leads to an optimum topology with very little initial information in acceptable time consumption. The method is applied to the design of a microstrip component in which the topology gradient is directly used as a direction of descent. However, in some ill‐behavior problems, topology gradient is not sufficient to converge to the global optimum. In the latter case, the basic TG is coupled with a genetic algorithm (GA) to make a more suitable algorithm for solving local optima problems. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008. 相似文献
72.
Ann M. Hagni M.S. Richard D. Hagni Ph.D. Christelle Demars B.S. 《JOM Journal of the Minerals, Metals and Materials Society》1991,43(4):28-30
Reflected light microscopy can contribute important information regarding the mineralogy, mineral abundance, internal textures, sizes and shapes of particles in electric arc furnace (EAF) dusts. Scanning electron microscopy-energy dispersive spectroscopy and electron microprobe analysis are useful to determine the chemical compositions of the specific mineral grains in the dust particles. Furthermore, the mineralogical reactions that have taken place during the pyro-metallurgical treatment of EAF dusts and the mineralogy and textural character of those treated dust samples can be directly observed by reflected light microscopy. Such studies are useful in monitoring the efficiency of experimental pyrometallurgical treatment of EAF dusts which are designed to render them nonhazardous. 相似文献
73.
Michel Le Bras Serge Bourbigot Christelle Delporte Catherine Siat Yannick Le Tallec 《火与材料》1996,20(4):191-203
The study compares five new intumescent additive mixtures and a carbonizing additive system with the ammonium polyphosphate–pentaerythritol system and additive formulations previously developed in laboratory in terms of fire retardancy of polypropylene-based formulations. The mixture of diammonium pyrophosphate and polyols produced by agrochemical industry xylitol and d-sorbitol (carbonization agent) are FR additive mixtures of interest for polyolefins. Moreover, the FR performance of the mixture of ammonium polyphosphate and polyamide-6 is reported. It is proposed that boric acid salts have to be developed as precursors for carbonization catalytic species. A thermal analysis study shows that FR performances and amounts of carbonaceous materials resulting from the thermal degradation of the additive mixtures are not related. An additional compilation of previous spectroscopic studies by the laboratory confirms that the intumescent process results from the formation of polyaromatic species and that FR systems maintain acidic species in a relatively high temperature range. An ESR study discusses the presence of π radicals in the protective coating formed using the additive systems. It provides information on the size of the carbonaceous structures in the materials and the presence of crystalline phases in the coating. Finally, the participation of free radicals in the formation of chemical bonds between the materials produced from the additives and the products of the degradation of the polymer is discussed. 相似文献
74.
Shan Bai Sarya Aziz Maryam Khodadadi Christelle Bou Mitri Richard St-Louis Selim Kermasha 《Journal of the American Oil Chemists' Society》2013,90(3):377-389
The synthesis of medium-long-medium type structured lipids (SL) by the interesterification of tricaprylin (TC) and trilinolenin (TLN), using selected commercial lipases from Rhizomucor miehei (Lipozyme RM IM) and Candida antarctica (Novozym 435) was investigated. Although the bioconversion yield (BY) for Lipozyme RM IM (24.7 %) was close to that for Novozym 435 (24.0 %), the initial enzyme activity was 6.3 μmol CLnC/g enzyme/min and 1.6 μmol CLnC/g enzyme/min, respectively. Lipozyme RM IM was subsequently selected for further investigation. The structural analyses of SL indicated that the major products were 1,3-dicapryl-2-linolenyl glycerol (CLnC) and 1(3)-capryl-2,3(1)-dilinolenyl glycerol (CLnLn). In order to optimize the BY, selected parameters were investigated. The experimental results showed that using hexane as the reaction medium, at an initial water activity (a w ) of 0.06, 10 mg solid enzyme/mL, substrate molar ratio of TC to TLN of 6:1 and a reaction time of 9 h, resulted in the highest BY (73.2 %). Using the optimized conditions, the effects of TLN concentration and other selective parameters, including the denaturation of the enzyme, controlling the a w and the addition of silica gel, on the mass productivity (P M), enzymatic productivity (P E) and volumetric productivity (P V ) of the interesterification reaction, were also investigated. 相似文献
75.
Performances of RO and NF processes for wastewater reuse: Tertiary treatment after a conventional activated sludge or a membrane bioreactor 总被引:1,自引:0,他引:1
Wastewater reclamation requires processes and technologies having the ability to reduce the presence of micropollutants which are not wholly treated in conventional WWTP. Due to the complexity of membrane-solute interactions and the diversity of secondary treatment effluent (STE) matrices, deeper investigations are required to identify the major foulant species and more specifically their behaviour at high concentration in real waters. This study investigates the rejection and fouling potential of nanofiltration (NF) and low-pressure reverse osmosis (RO) membranes with two STEs sampled from i) a conventional activated sludge process coupled with ultrafiltration (CAS-UF) and from ii) a membrane bioreactor MBR (AquaRM®, SAUR (France)). Whatever the origin of the effluent, RO seems to be the best solution to prevent pollution of tertiary effluents (expected result) but also to obtain low fouling levels. The different composition and molecular weight distribution of MBR and CAS-UF effluents can explain the different fouling behaviours that were observed. 相似文献
76.
Direct Synthesis of Partially Modified 2′‐O‐Pivaloyloxymethyl RNAs by a Base‐Labile Protecting Group Strategy and their Potential for Prodrug‐Based Gene‐Silencing Applications
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Annabelle Biscans Maxence Bos Dr. Anthony R. Martin Nicholas Ader Prof. Dr. Georg Sczakiel Dr. Jean‐Jacques Vasseur Dr. Christelle Dupouy Dr. Françoise Debart 《Chembiochem : a European journal of chemical biology》2014,15(18):2674-2679
An original and straightforward synthesis of partially modified 2′‐O‐pivaloyloxymethyl‐substituted (PivOM‐substituted) oligoribonucleotides has been achieved. The aim of this 2′‐enzymolabile modification was to enhance nuclease stability of RNA and transmembrane transport. To make these modified RNAs easily available we developed a base‐labile protecting group strategy with standard protections for nucleobases (acyl) and phosphates (cyanoethyl), a Q‐linker and two different acetalester protection groups for 2′‐OH: propionyloxymethyl (PrOM) and PivOM. Interestingly, orthogonal deprotection conditions based on anhydrous butylamine in THF were found to remove propionyloxymethyl groups selectively, while preserving PivOM groups. Duplex stability, circular dichroism studies and nuclease resistance, as well as the ability to inhibit gene expression of modified 2′‐O‐PivOM RNA, were evaluated. 相似文献
77.
Christelle Bnard Gaëtan Math Pascal Fornara Jean-Luc Ogier Didier Goguenheim 《Microelectronics Reliability》2009,49(9-11):1008-1012
In this paper, we analyze the impact of various process steps on the reliability of PMOSFET’s submitted to Negative Bias Temperature Instabilities stress conditions. We give some evidence of the complete thermal anneal of interface states induced by NBTI and investigate the influence of the oxide thickness and of the final forming gas anneal. Then we show a NBTI lifetime improvement after a fluorine implant through the gate and an arsenic bulk doping value increase. 相似文献
78.
Claudia Gordin Christelle Delaite Hussein Medlej Delphine Josien-Lefebvre Kamal Hariri Mihai Rusu 《Polymer Bulletin》2009,63(6):789-801
We described the obtention of well-defined ABC star block copolymers through the use of a new heterotrifunctional initiator.
That way, well-defined PCL-arm–PS-arm–PLLA star block copolymers have been synthesized from a heterotrifunctional initiator
bearing two hydroxyl groups able to initiate ROP of CL and LLA (using Sn(Oct)2 as coinitiator) and a bromide function able to initiate ATRP of styrene. 相似文献
79.
Arsenic removal by adsorption on iron(III) phosphate 总被引:1,自引:0,他引:1
Lenoble V Laclautre C Deluchat V Serpaud B Bollinger JC 《Journal of hazardous materials》2005,123(1-3):262-268
Under natural conditions, arsenic is often associated with iron oxides and iron(III) oxidative capacity towards As(III) is well known. In this study, As(III) and As(V) removal was performed using synthesised iron(III) phosphate, either amorphous or crystalline. This solid can combine (i) As(III) oxidation by iron(III) and (ii) phosphate substitution by As(V) due to their similar properties. Results showed that adsorption capacities were higher towards As(III), leading to Fe2+ and HAsO4(2-) leaching. Solid dissolution and phosphate/arsenate exchange led to the presence of Fe3+ and PO4(3-) in solution, therefore various precipitates involving As(V) can be produced: with Fe2+ as Fe3(AsO4)2.8H2O(s) and with Fe3+ as FeAsO4.2H2O(s). Such formations have been assessed by thermodynamic calculations. This sorbent can be a potential candidate for industrial waste treatment, although the high release of phosphate and iron will exclude its application in drinking water plants. 相似文献
80.
Claire Goursaud Naufal M. Saad Younes Zouine Anne Julien-Vergonjanne Christelle Aupetit-Berthelemot Jean-Pierre Cances Jean-Michel Dumas 《电信纪事》2004,59(9-10):1212-1227
This paper investigates the Parallel Interference Cancellation technique in Direct Sequence Optical Code Division Multiple Access (ds-ocdma) system. In the proposed system, the estimated interference is removed from the received signal. We have developped a new approach to obtain the analytical expression of error probability in chip synchronous case, for Optical Orthogonal Codes (ooc). We have shown that under specific conditions between codes parameters and users’ number, the interference can be completely neutralized. Simulation results have validated the theoretical analysis. It is shown that the proposed receiver is effective in reducing significantly the effects of Multiple Access Interference (mai) compared to other interference cancellation systems. 相似文献