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71.
The recent observation of higher quark combinations, tetraquarks and pentaquarks, is a strong indication of more exotic hadrons. Using Z2 and Z3 symmetries and standard model data, a general quark combination producing new hadronic states is proposed in terms of polygon geometries according to the Dynkin diagrams of  n affine Lie algebras. It has been shown that Z2,3 invariance is crucial in the determination of the mesonic or the baryonic nature of these states. The hexagonal geometry is considered in some details producing both mesonic and baryonic states. A general class of this family is also presented. 相似文献
72.
73.
Mohamed Fathi Karoui Hassane Alla Abderrazak Chatti 《Nonlinear Analysis: Hybrid Systems》2010,4(4):766-774
In this paper we develop a method of monitoring dynamic processes based on rectangular hybrid automats. This method takes into account the behavior of the system and the evolution of its parameters. A failure during the execution of the process can lead to a dysfunctional state in the system.The monitoring system, we propose, makes it possible to detect this state of dysfunction as soon as possible thanks to the reachability analysis. 相似文献
74.
Ronghuan Zhang Nicolas Dubouis Manel BenOsman Wei Yin Moulay T. Sougrati Daniel A. D. Corte Domitille Giaume Alexis Grimaud 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(14):4619-4623
Recently, IrV‐based perovskite‐like materials were proposed as oxygen evolution reaction (OER) catalysts in acidic media with promising performance. However, iridium dissolution and surface reconstruction were observed, questioning the real active sites on the surface of these catalysts. In this work, Sr2MIr(V)O6 (M=Fe, Co) and Sr2Fe0.5Ir0.5(V)O4 were explored as OER catalysts in acidic media. Their activities were observed to be roughly equal to those previously reported for La2LiIrO6 or Ba2PrIrO6. Coupling electrochemical measurements with iridium dissolution studies under chemical or electrochemical conditions, we show that the deposition of an IrOx layer on the surface of these perovskites is responsible for their OER activity. Furthermore, we experimentally reconstruct the iridium Pourbaix diagram, which will help guide future research in controlling the dissolution/precipitation equilibrium of iridium species for the design of better Ir‐based OER catalysts. 相似文献
75.
Solano-Peralta A Sosa-Torres ME Flores-Alamo M El-Mkami H Smith GM Toscano RA Nakamura T 《Dalton transactions (Cambridge, England : 2003)》2004,(16):2444-2449
For the first time, HF-EPR (94.5 GHz) spectroscopy has been used to determine crystal field parameters in chromium(III) coordination compounds. The large zero-field splitting parameters of the dark-green photochromic trans-RSSR-[CrCl(2)(cyclam)](2)ZnCl(4), 1, the red-purple trans-RSSR-[CrCl(2)(cyclam)]Cl, 2, and the red-purple trans-RSSR-[CrCl(2)(cyclam)]Cl.4H(2)O.0.5HCl, 3, where cyclam = 1,4,8,11-tetraazacyclotetradecane, have been obtained. A full analysis of EPR spectra at 94.5 GHz of diluted complexes 1, 2 and 3 at 300 K revealed that they are extremely sensitive to D and E values. The rhombic distortion was precisely determined for each compound. For 1, g= 2.01, D=-0.305 cm(-1), E= 0.041 cm(-1) and lambda=|E/D|= 0.1396; for 2, g= 2.01; D=-0.348 cm(-1), E= 0.042 cm(-1) and lambda=|E/D|= 0.1206 and for 3, g= 1.99, D=-0.320 cm(-1), E= 0.041 cm(-1) and ambda=|E/D|= 0.1281. The EPR study at 94.5 GHz at 10 K allowed us to confirm the sign of the D value for all compounds. These data indicate that at room temperature the crystal field is mainly rhombic and as the temperature decreases, the rhombicity of the D tensor increases slightly. These found differences between 1, 2 and 3 allowed us to establish the importance of the intermolecular interactions in the solid state due to different hydrogen bonding networks in their crystalline arrangement. 相似文献
76.
Simon Salager Fredéric Jamin Moulay Saïd El Youssoufi Christian Saix 《Comptes Rendus Mecanique》2006,334(6):393-398
This paper concerns the influence of temperature on the water retention curve of porous media. We present a model based on the differential of suction as a function of temperature, water content and void ratio. When adjusted for a given temperature, this model is able to predict the curve for any temperature. The model was validated by several tests on a ceramic (terra cotta) and a clayey silty sand at 20 and 60?°C. The application of the model to data found in the literature confirms its predictive power for a wide range of porous materials. To cite this article: S. Salager et al., C. R. Mecanique 334 (2006). 相似文献
77.
Jean-Yves Delenne Moulay Saı̈d el Youssoufi Jean-Claude Bénet 《Comptes Rendus Mecanique》2002,330(7):475-482
The modelling of mechanical behaviour and rupture of cohesive granular media is carried out on a model medium made of aluminium cylinders and cohesive bonds playing the role of cohesion points. The mechanical behaviour of the cohesion point is studied under different loading situations (compression, traction, shearing, torque). The results are introduced into a code, which is based on a discrete element method extended to the cohesive case. The validation is achieved with compression tests of macroscopic samples. We notice a good correlation between simulation and experiment on the mechanical behaviour, on the appearance of fractures and their propagation. To cite this article: J.-Y. Delenne et al., C. R. Mecanique 330 (2002) 475–482. 相似文献
78.
Muhammad Mansha Muhammad Taha El Hassane Anouar Nisar Ullah 《Arabian Journal of Chemistry》2021,14(7):103211
An enhanced acetylcholinesterase (AChE) activity is a hallmark in early stages of Alzheimer's ailment that results in decreased acetylcholine (ACh) levels, which in turn leads to cholinergic dysfunction and neurodegeneration. Consequently, inhibition of both AChE and butyrylcholinesterase (BChE) is important to prolong ACh activity in synapses for the enhanced cholinergic neurotransmission. In this study, a series of new fluoroquinolone derivatives (7a-m) have synthesized and evaluated for AChE and BChE inhibitory activities. The screening results suggested that 7 g bearing ortho fluorophenyl was the most active inhibitor against both AChE and BChE, exhibiting IC50 values of 0.70 ± 0.10 µM and 2.20 ± 0.10 µM, respectively. The structure–activity relationship (SAR) revealed that compounds containing electronegative functions (F, Cl, OMe, N and O) at the ortho position of the phenyl group exhibited higher activities as compared to their meta- and/or para substituted counterparts. Molecular docking studies of synthesized compounds 7a, 7g, 7j and 7l docked into the active site of AChE and 7a-f docked into the active site of BChE revealed that these compounds exhibited conventional H-bonding along with π-π interaction with the active residues of AChE through their electronegative functions and phenyl ring, respectively. All the synthesized compounds are characterized by spectroscopic methods including FT-IR, 1H- and 13C NMR as well as elemental analysis. This is the first example of fluoroquinolone-based cholinesterase inhibitors. 相似文献
79.
80.
Hassane?Assaaoudi Ian?S.?ButlerEmail author Janusz?Kozinski Francine?Bélanger-Gariépy 《Journal of chemical crystallography》2005,35(10):809-820
Colourless crystals of a new, dicationic, hydropyrophosphate dihydrate salt, KHMgP2O7⋅ 2H2O, are formed, when a mixture of aqueous equimolar solutions of MgCl2⋅4H2O and K4P2O7, at pH 2.12, are left to stand at ambient temperature for 4 days. The new pyrophosphate salt has been characterized by single-crystal
X-ray diffraction, IR and Raman spectra, and DSC-TG thermal analysis. The structure consists of alternating layers of [HP2O7]3− groups and MgO6 octahedra, joined by K+ ions and bridging hydrogen bonds. The [P2O7]4− anions exhibit a bent eclipsed conformation. The absence of coincidences for the majority of the IR and Raman bands is in
accord with the centrosymmetric structure of the material. The 31P chemical shift tensor components have been determined from the solid-state MAS NMR spectra. The structural changes occurring
during thermal decomposition have been examined by TG-DSC, X-ray powder diffraction (XRD) and IR spectroscopy. When the new
pyrophosphate salt is heated gradually, it first becomes amorphous and then condenses to chain metaphosphates. 相似文献