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Urea-assisted morphological engineering of MFI nanosheets with tunable b-thickness

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Nano Research 2023年第10期16卷 12196-12206页

作者： Qiudi Yue Chaowei Liu Hongjuan Zhao Honghai Liu Pierre Ruterana Jiaqi Zhao Zhengxing Qin Svetlana Mintova Laboratoire Catalyse et Spectrochimie ENSICAENUNICAENCNRSCaen 14050France Petrochemical Research Institute PetroChina Company LimitedBeijing 100195China Centre de Recherche sur les Ions les Matériaux et la PhotoniqueCIMAP-ENSICAENCNRS UMR 6252Caen 14050France State Key Laboratory of Heavy Oil Processing College of Chemical EngineeringChina University of Petroleum(East China)Qingdao 266580China

Engineering of crystal morphology affects the catalytic and adsorption properties of zeolitic *** the anisotropic diffusion of molecules derived from its topological features,MFI zeolite nanosheets with short b-axis thickness are highly desired materials to reduce diffusion ***,the design and development of eco-friendly synthesis protocols with reasonable cost and high efficiency remain ***,we reported a systematic study on the synthesis of MFI nanosheets using urea as an *** silicalite-1 and ZSM-5 zeolites(MFI type framework structure)with controllable b-thicknesses ranging from 50–200 nm were achieved by optimizing the synthetic parameters including water content,urea and SDA *** concentration of hydroxide anions was found to dominate the crystallization kinetics compared with the counterpart tetrapropylammonium cations(TPA^(+)).To facilitate the crystal growth of MFI zeolites in the presence of urea,the ratio OH−/SiO_(2)has to be higher than 0.2,independent of the TPA+*** role of urea in the assistance of plate-like crystal formation through the inhibition of(010)facet growth was revealed by electron microscopy and infrared(IR)spectroscopy *** developed strategy for morphological engineering is not limited to the MFI-type zeolite and can be applied to other frameworks depending on the intrinsic properties of additive molecules and the interactions between them.

关键词： MFI zeolite synthesis nanosheets additives crystal morphology

Effect of Scanning Beam Profile to Fabricate Fused Fiber Tapers by CO_2 Laser Irradiation Method

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光学学报 2003年第S1期23卷 121-122页

作者： Bayle Fabien Luo Aiping Marin Emmanuel Meunier Jean-Pierre Laboratoire TSI UMR CNRS 5516 Saint Etienne FranceLaboratoire TSI UMR CNRS 5516 Saint Etienne FranceLaboratoire TSI UMR CNRS 5516 Saint Etienne FranceLaboratoire TSI UMR CNRS 5516 Saint Etienne France

Beam uniformity is a crucial building block of CO2 experiments aimed at fusing and stretching optical fibers in a lossless manner. When the irradiation beam is expanded through a galvanometer mirror, ways to achieve b... 详细信息

关键词： of in on as it by Effect of Scanning Beam Profile to Fabricate Fused Fiber Tapers by CO2 Laser Irradiation Method

Implementation of a Roughness Element to Trip Transition in Large-eddy Simulation

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Journal of Thermal Science 2015年第1期24卷 30-36页

作者： J.Boudet J.-F.Monier F.Gao LMFA Ecole Centrale de Lyon Université de Lyon–umr cnrs 5509 69134 Ecully Cedex France PhD.Candidate Université de Lyon–umr cnrs 5509 69134 Ecully Cedex France

In aerodynamics, the laminar or turbulent regime of a boundary layer has a strong influence on friction or heat transfer. In practical applications, it is sometimes necessary to trip the transition to turbulent, and a common way is by use of a roughness element （e.g. a step） on the wall. The present paper is concerned with the numerical im- plementation of such a trip in large-eddy simulations. The study is carried out on a flat-plate boundary layer con- figuration, with Reynolds number Rex=l.3x 106. First, this work brings the opportunity to introduce a practical methodology to assess convergence in large-eddy simulations. Second, concerning the trip implementation, a volume source term is proposed and is shown to yield a smoother and faster transition than a grid step. Moreover, it is easier to implement and more adaptable. Finally, two subgrid-scale models are tested： the WALE model of Nic0ud and Ducros （Flow Turbul. Combust., vol. 62, 1999） and the shear-improved Smagorinsky model of Ldv^que et al. （J. Fluid Mech., vol. 570, 2007）. Both models allow transition, but the former appears to yield a faster transition and a better prediction of friction in the turbulent regime.

关键词： large-eddy simulation boundary layer roughness element transition tripping

The Guianese population of the fire ant Solenopsis saevissima is unicolonial

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Insect Science 2016年第5期23卷 739-745页

作者： Alain Lenoir Severine Devers Axel Touchard Alain Dejean lRBI Institut de Recherche sur la Biologie de I'lnsecte UMR CNRS 7261 Universite Francois Rabelais 37200 Tours cnrs Ecologie des Forets de Guyane (UMR CNRS 8172) Campus agronomique BP 316 97379 Kourou cedex Universite de Toulouse UPS INP Ecolab 118 route de Narbonne 31062 Toulouse and CNRS Ecolab (UMR-CNRS 5245) 31062 Toulouse France

In this study, conducted in French Guiana, a part of the native range of the fire ant Solenopsis saevissima, we compared the cuticular hydrocarbon profiles of media workers with previous results based on intraspecific aggressiveness tests. We noted a strong congruence between the two studies permitting us to delimit 2 supercolonies extending over large distances （up to 54 kin）, a phenomenon known as unicoloniality. Solenopsis geminata workers, taken as an out-group for cluster analyses, have a very different cuticular hydrocarbon profile. Because S. saevissima has been reported outside its native range, our conclusion is that this species has the potential to become invasive because unicoloniality （i.e., the main attribute for ants to become invasive） was shown at least for the Guianese population.

关键词： biological invasions cuticular hydrocarbons fire ants unicoloniality

Decay of Solutions to a Linear Viscous Asymptotic Model for Water Waves

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Chinese Annals of Mathematics,Series B 2010年第6期31卷 841-854页

作者： Olivier GOUBET Guillaume WARNAULT LAMFA umr 6140 cnrs UPJV 33 rue Saint-Leu Amiens 80039 cedex France LMPT umr cnrs 6083 Université Francois Rabelais Parc Grandmont 37000 Tours France

The authors discuss a linear viscous asymptotic model for water waves and the decay rate of solutions towards the equilibrium.

关键词： Water waves Viscous asymptotic models Nonlocal operators Long-time asymptotics

Visualisation and personalisation of multi-representations city models

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International Journal of Digital Earth 2020年第5期13卷 627-644页

作者： Jérémy Gaillard Adrien Peytavie Gilles Gesquiére LIRIS UMR CNRS 5205Univ LyonVilleurbanneFrance Oslandia LyonFrance

City models have a wide variety of uses that require different kind of data representation or data *** a dynamic model that enables picking the right representations(meshes,volumetric data,point cloud,etc.)can prove useful to adapt an application to each user’s *** this paper,we present an original method to create personalised visualisations of 3D city models on the *** organising the server data in a hierarchy of tiles,we are able to generate personalised models based on the user’s *** preferences take the shape of a set of rules that apply to each tile or city object and allow the user to choose which representation of the object to use depending on its position or semantic information(classification,height,etc.).Our method is designed around existing standards,guaranteeing the interoperability of the produced models.

关键词： 3D visualisation web geospatial city model

Testing protocols in Internet of Things by a formal passive technique

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Science China(Information Sciences) 2014年第3期57卷 6-18页

作者： Xiaoping CHE Stephane MAAG Insititut Mines-Telecom/Telecom SudParis CNRS UMR 5157Evry 91000France

In recent years,Extensible Messaging and Presence Protocol(XMPP)is gaining momentum in Internet of Things(IoT).It has been widely used in chatting,message exchanging and unique *** a matter of course,it raises an interesting issue:how to formally test the conformance and performance of XMPP in IoT *** conformance testing of communicating protocols is a functional test that verifies whether the behaviors of the protocol satisfy defined requirements,performance testing is a qualitative and quantitative test that aims at checking whether the performance requirements of the protocol are satisfied under certain *** this paper,we present a logic-based passive testing approach that can test both the conformance and the performance of XMPP protocol through real execution traces and formally specified *** evaluate and assess our methodology,we present a developed prototype and the experiments with a set of XMPP ***,the relevant verdicts and conclusions are provided.

关键词： Internet of Things passive testing formal methods XMPP

Relaxor behaviour and phase transition of perovskite ferroelectrics-type complex oxides(1–x)Na_(0.5)Bi_(0.5)TiO_3–xCaTiO_3 system

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Journal of Advanced Ceramics 2018年第2期7卷 124-142页

作者： Roy ROUKOS Nissrine ZAITER Denis CHAUMONT Laboratoire Interdisciplinaire Carnot de Bourgogne umr 6303 cnrs Université de Bourgogne

Polycrystalline powders of (1–x)Na_(0.5)Bi_(0.5)TiO_3–xCaTiO_3 ((1–x)NBT–xCT, 0 ≤ x ≤ 0.55) have been synthesized by solid state route. The effects of simultaneous substitution of Na^+/Bi^(3+) at A-site in NBT on structural and dielectric properties were investigated. X-ray diffraction analysis revealed the phase transition from rhombohedral structure(x = 0) to orthorhombic structure(x ≥0.15). A distinct behaviour in dielectric properties was obtained, where for x = 0, a normal ferroelectric behaviour was observed, whereas for x ≥ 0.15, a broad dielectric anomaly was revealed such that the maximum temperature(T_m) strongly depended on the frequency and shifted towards low temperature with CT. The dielectric dispersion indicated a relaxor behaviour revealed by the degree of diffuseness and modelled via Vogel–Fulcher relation. The study highlighted the relaxor behaviour as a function of frequency and proved the transformation from a relaxor high-frequency dependence to a paraelectric phase at temperature T_s. The distinct variation of the Raman spectra at room temperature was correlated with X-ray diffraction results and proved the already mentioned transition. On heating(-193–500 ℃), the Raman spectra confirmed the structural stability(Pnma) of the materials. The phonon behaviour for x = 0.15 was discussed in terms of the appearance of polar nanoregions(PNRs) into a non-polar orthorhombic matrix responsible of the relaxor behaviour. For x = 0.20, unchanged phonon behaviour confirmed the variation in dielectric behaviour where the solids transformed from a relaxor to a paraelectric state without structural phase transition.

关键词： relaxor behaviour dielectric properties Vogel–Fulcher relationship polar nanoregions (PNRs) X-ray diffraction Raman spectroscopy

The contribution of solid-state chemistry in the determination of multicomponent phase diagrams

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Rare Metals 2006年第5期25卷 576-581页

作者： Jean Claude Tedenac Franck Gascoin Didier Ravot Université Montpellier 2 LPMC-umr-cnrs-5617 MontpellierFrance

For a long period of time, the determination of phase diagrams was only supported by experiments related to thermal effects or thermodynamic measurements： thermal analysis, calorimetric measurements, vapor pressures, and EMF measurements. As a matter of fact, solid-solid transformations were not so accurately determined and could not be taken into account in the system＇s analysis. First, X-ray diffraction methods were used as a support for the thermal analysis. Second, the implementation of novel tools in structural analysis （for example, the Rietveld method） has permitted to increase the knowledge of phase stability. Finally, modeling the phases using a Calphad method needed increasingly more structural results to determine and better understand the phase diagrams. On the other hand, the Calphad method has been widely developed for metallic systems, for oxide systems, and in the past 10 years, for some semi-conductor systems, for example, gallium arsenide, cadmium telluride, and lead telluride systems. In such applications, it is very important to bring point defects in the modeling of the phases to map the defects as a function of the chemical composition. Owing to its complexity, this characteristic, the knowledge of which is crucial for the understanding and the control of potential physical applications, was ignored in the previous assessment of semi-conductor systems.

关键词： thermodynamic modeling solid-state chemistry phase diagram