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Antimicrobial Activity of the Methanolic Extract and Compounds from the Stem Bark of Drypetes tessmanniana

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Chinese Journal of Integrative Medicine 2010年第4期16卷 337-343页

作者： Victor Kuete Marlise D.J.Dongfack Armelle T.Mbaveng Marie-Christine Lallemand Hanh T.Van-Dufat jean-duplex wansi Elisabeth Seguin Francois Tillequin jean Wandji Department of Biochemistry Faculty of ScienceUniversity of Dschang.P.O.Box 67 DschangCameroon Department of Organic Chemistry Faculty of ScienceUniversity of Yaounde I.P.O.Box 812 YaoundeCameroon Laboratoire de Pharmacognosie de I'Universite Paris Descartes UMR/CNRS N° 8638Faculte des Sciences Biologiques et Pharmaceutiques4-Avenue de I'Observatoire75006 ParisFrance Department of Biochemistry Faculty of ScienceUniversity of Yaounde IP.O.Box 812 YaoundeCameroon Department of Chemistry University of DoualaFaculty of ScienceP.O.Box 24157 DoualaCameroon Laboratoire de Pharmacognosie UFR de Medecine Pharmacie Rouen22-Bid Gambetta76183 Rouen Cedex 1France

Objective： To evaluate the antimicrobial activity of the methanol extract from the stem bark of Drypetes tessmanniana, fractions （DTB1-5） as well as compounds [friedelin （2）, 3,7-dioxofriedelane （3）, 3,15-dioxofriedelane （4）, 313 -O-（E）-3,5-dihydroxycinnamoyl-11 -oxo-olean-12-ene （6）, and 313,6 α -dihydroxylup- 20（29）-ene （7）. Methods： Agar disc diffusion was used to determine the sensitivity of the above samples, whilst the microdilution method was used for the determination of the minimal inhibitory concentration （MIC） and the minimal microbicidal concentrations （MMC）. Results： The diffusion test showed that the crude extract was able to prevent the growth of all tested organisms. All other samples showed selective activity. The inhibitory effect of the fraction DTB2 was noted on 63.7%, that of DTB1 and DBT3 on 54.6%, whilst DTB4 and DTB5 were active on 9.1% of the 11 tested organisms. The tested compounds prevented the growth of 81.8% of the tested microbial species for compounds 3 and 4, 36.7% for compound 6, and 18.2% for compound 7. The results of the MIC determinations indicated perceptible values for DTB and compound 4 on 81.8% of the tested organisms. For other samples, MICs were detected on 0-63.7%. The lowest MIC value （78.12 μg/mL） for the crude extract and fractions （DTB2） was observed on M. audouinii. The corresponding value for isolated compounds （156.25 μg/ mL） was noted with compounds 3 on S. faecalis and 4 on M. audouinii. The results of the MMC determination suggested that the microbicidal effect of most of the tested samples on the studied microorganisms could be expected. Conclusion： The methanol extract from the stem bark of Drypetes. tessmanniana （Euphorbiaceae） as well as some of the isolated compounds might be potential sources of new antimicrobial drues.

关键词： Drypetes tessmanniana Euphorbiaceae compounds antimicrobial activity

New proposals for coupling cavitation models with laminar/turbulent transition models:application to a cavitation sheet over a NACA 16012

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Journal of Hydrodynamics 2024年第4期36卷 725-740页

作者： jean Decaix Institute of Sustainable Energy School of EngineeringHES-SO Valais-WallisHES SO University of Applied Sciences and Arts Western SwitzerlandDelemontSwitzerland

Since 1970s,several experimental works revealed that the cavitation sheet inception does not occur at the minimum pressure location but further downstream at the location of a laminar/turbulent *** of the cavitation models use the saturation vapour pressure as a threshold to initiate the production of vapour and therefore,are not able to capture such *** this paper,three modifications of the Schnerr and Sauer cavitation model are proposed and coupled with an algebraic laminar/turbulent transition *** to a NACA 16012 profile shows the ability of the modifications to move the cavitation inception at the right location compared with the *** of them,based on the multiplication of the evaporation term by the square of the turbulent intensity seems promising.

关键词： Reynolds-average Navier-Stokes laminar/turbulent transition cavitation sheet NACA 16012 hydrofoil

A Review on Thermophysical Properties and Nusselt Number Behavior of Al2O3 Nanofluids in Heat Exchangers

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Journal of Thermal Science 2021年第2期30卷 418-431页

作者： ISSA Roy jean College of Engineering West Texas A&M UniversityCanyonTexas 79016USA

During the last several years,the increase in cooling power requirements for heat exchangers have led to an escalation in heat transfer studies being performed on the use of nanofluids as heat transfer ***,limited effort has been attempted to relate and interpret these findings or the anomalies associated with *** paper compiles test data from several studies conducted on different types of heat *** this review,a concentrated effort is spent to clarify the ambiguities regarding the effect of nanoparticle size on the nanofluid thermal conductivity and Nusselt *** show that the nanofluid thermal conductivity is not influenced by the nanoparticle size,but by the clustering of the particles *** less compact the structure of the nanoparticle clustering is,the greater the enhancement in the nanofluid thermal conductivity *** were also compiled to interpret the relation between the nanofluid flow pattern,nanoparticles volume fraction in the base fluid,and the convective heat *** results from the majority of the heat exchanger studies show an increase in the heat transfer coefficient with the increase in nanoparticle volume ***,studies conducted on plate heat exchanges display some *** the majority of the heat exchanger studies with the exception of few,the decrease in the nanoparticle size is shown to result in an enhancement of the bulk fluid Nusselt *** test data also reveal that the effectiveness of the alumina nanoparticles is dependent on the flow *** increase in the nanoparticles concentration is shown to result in an increase in the nanofluid heat transfer enhancement as the fluid is transitioning from laminar to turbulent *** general,the smaller the nanoparticle size is,the greater the enhancement in the fluid Nusselt number is.

关键词： heat exchanger Nusselt number alumina nanofluid

Phase coexistence properties of liquid mercury:a simulation study

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Rare Metals 2006年第5期25卷 567-571页

作者： jean-Louis Bretonnet jean-Marc Bomont Laboratoire de Physique des Milieux Denses Université Paul Verlaine1bd F.D.Arago57078 MetzCedex 3France

The thermophysical properties of expanded liquid mercury have been investigated along the liquid-vapor coexistence curve by using Monte Carlo and Molecular Dynamic simulations. For the purpose, an empirical state dependent interatomic potential for the region of dense metallic liquid is used, while the state dependence is not necessary near the cliffcal point. In order to test the validity of this potential, we determine the surface layering and the sound velocity, two properties very sensitive to the choice of the potential. Our results are in quite good agreement with other theoretical results and to the experimental data available in the literature.

关键词： mercury simulation phase coexistence liquid state

Emoti-Shing: Detecting Vishing Attacks by Learning Emotion Dynamics through Hidden Markov Models

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Journal of Intelligent Learning Systems and Applications 2024年第3期16卷 274-315页

作者： Virgile Simé Nyassi Franklin Tchakounté Blaise Omer Yenké duplex Elvis Houpa Danga Magnuss Dufe Ngoran jean Louis Kedieng Ebongue Fendji Department of Mathematics and Computer Science Faculty of Science University of Ngaoundr Ngaoundr Cameroon Department of Computer Engineering University Institute of Technology University of Ngaoundr Ngaoundr Cameroon

This study examines vishing, a form of social engineering scam using voice communication to deceive individuals into revealing sensitive information or losing money. With the rise of smartphone usage, people are more susceptible to vishing attacks. The proposed Emoti-Shing model analyzes potential victims’ emotions using Hidden Markov Models to track vishing scams by examining the emotional content of phone call audio conversations. This approach aims to detect vishing scams using biological features of humans, specifically emotions, which cannot be easily masked or spoofed. Experimental results on 30 generated emotions indicate the potential for increased vishing scam detection through this approach.

关键词： Social Engineering Hidden Markov Model Vishing Voice Mining

A major step toward efficient and stable single-material organic solar cells

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Science China Chemistry 2019年第9期62卷 1085-1086页

作者： jean Roncali Group Linear Conjugated Systems CNRS Moltech AnjouUniversity of Angers Department of Chemistry and SOOMCC Faculty of Chemistry and Chemical EngineeringBabes-Bolyai University

Organic photovoltaics (OPV) can potentially combine low cost, lightness, flexibility and low environmental impact. In less than two decades, the power conversion efficiency(PCE) of OPV cells has increased from 1 to mo... 详细信息

关键词： Organic photovoltaics (OPV) power conversion efficiency(PCE) stable single-material organic solar cells

Bound and Resonating Multiquark Configurations

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Chinese Physics Letters 2024年第8期41卷 8-12页

作者： jean-Marc Richard Institut de Physique des 2 Infinis de Lyon Université Claude Bernard(Lyon 1) CNRS-IN2P34 rue Enrico Fermi69622 VilleurbanneFrance

We review the predictions of quark models for multiquark configurations that are bound or resonant states,and compare different methods for estimating the properties of resonances.

关键词： quark Configuration resonant

On the Contribution of Wu Wen-Tsün to Algebraic Topology

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Journal of Systems Science & Complexity 2019年第1期32卷 3-36页

作者： BRASSELET jean-Paul I2M (CNRS)-Aix-Marseille University

The aim of this article is to present the contribution of Wu Wen-Tsün to Algebraic Topology and more precisely to the theory of characteristic classes. Several papers provide complete and welldocumented biography and academic career of Wu Wen-Tsün, in particular, Hudecek, 2014; O'Connor and Robertson, 2006; Wen-Tsün Wu's Academic Career, 2006; Selected works of Wen-Tsun Wu, *** author does not repeat the details provided in these papers concerning the Wu Wen-Tsün's bibliography, we will just mention people involved in the Wu Wen-Tsün's period in *** addition to Wu Wen-Tsün's papers, the Dieudonné's book(Dieudonné, 1960) provides an excellent presentation of main results of Wu Wen-Tsün in Algebraic and Differential Topology. The author will use and abuse of this book(and refer to) when *** the introduction, the author recalls mainly historical facts concerning the contribution of Wu Wen-Tsün to Algebraic Topology. The second section shows speci?cally the contribution of Wu WenTsün to the Stiefel-Whitney classes and introduces the third section, dealing with the(real) Wu *** author provides de?nition, properties as well as further developments and generalizations of the Wu classes. The fourth and ?fth sections are devoted to recent applications: In Cobordism theory and in Mathematical Physics. The author notices that Wu classes have been used as well in other domains,in particular surgery theory(Madsen and Milgram, 1979). The last section concerns the complex Wu classes and shows that the more recent Mather classes coincide with the previously de?ned complex Wu classes, that is a result from Zhou(1994)(see also Liu, 1996).This article is devoted to the contribution of Wu Wen-Tsün to the theory of Characteristic Classes,which coincides with his "French period"(1947–1951). However, speaking of Algebraic Topology, it is worthwhile to mention the important contribution of Wu Wen-Tsün to the Theory of realization of complexes or manifolds in Eucl

关键词： Algebraic topology characteristic class cobordism theory mathematical physics Wu Class

Best practices for model-based and simulation-aided engineering of power transmission and motion control systems

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Chinese Journal of Aeronautics 2019年第1期32卷 186-199页

作者： jean-Charles MARE Institut Clément Ader (CNRS UMR 5312)

This paper deals with the modelling and simulation of aircraft systems, in particular for power transmission and control. It is intended to review, propose and disseminate best practices for making model-based/simulation-aided engineering more efficient at any phase of the system life cycle. The proposals are aimed at creating value, not only by increasing the performance of the product under study but also by shortening the time to market, capitalizing knowledge, mitigating risks and facilitating concurrent engineering. The needs associated with the engineering activities are firstly identified to define a set of requirements for the models. Then, these requirements are used to drive the considerations leading to model development, focusing in particular on the process,modelled physical effects, modelling level, model architecting and concurrent engineering. The third part deals with the model implementation, giving special consideration to the different types of models, causalities, parameterization, implementation and verification. Each part is illustrated by examples related to safety critical actuators.

关键词： Actuator Aerospace Architecture Causality Modelling Motion control Power transmission Simulation