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1.
Queueing Systems - In this paper, a stochastic model of a call center with a two-level architecture is analyzed. A first-level pool of operators answers calls, identifies, and handles non-urgent... 相似文献
2.
Yoanes Maria Vianney Pit Preckwinkel Swantje Mohr Prof. Dr. Klaus Weisz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(70):16910-16922
A parallel quadruplex derived from the Myc promoter sequence was extended by a stem-loop duplex at either its 5′- or 3′-terminus to mimic a quadruplex–duplex (Q–D) junction as a potential genomic target. High-resolution structures of the hybrids demonstrate continuous stacking of the duplex on the quadruplex core without significant perturbations. An indoloquinoline ligand carrying an aminoalkyl side chain was shown to bind the Q–D hybrids with a very high affinity in the order Ka≈107 m −1 irrespective of the duplex location at the quadruplex 3′- or 5′-end. NMR chemical shift perturbations identified the tetrad face of the Q–D junction as specific binding site for the ligand. However, calorimetric analyses revealed significant differences in the thermodynamic profiles upon binding to hybrids with either a duplex extension at the quadruplex 3′- or 5′-terminus. A large enthalpic gain and considerable hydrophobic effects are accompanied by the binding of one ligand to the 3′-Q–D junction, whereas non-hydrophobic entropic contributions favor binding with formation of a 2:1 ligand-quadruplex complex in case of the 5′-Q–D hybrid. 相似文献
3.
Eder Toms‐Mendivil Marc Devillard Vianney Regnier Jacques Pecaut David Martin 《Angewandte Chemie (International ed. in English)》2020,59(28):11516-11520
Oxyallyl derivatives are typically elusive compounds. Even recently reported “stabilized” 1,3‐diaminooxyallyl species are still highly reactive and have short lifetimes at room temperature. Herein, we report the synthesis and preliminary study of mesoionic pyrimidine derivatives that feature 1,3‐bis(dimethylamino)oxyallyl patterns with an unprecedented level of stabilization. The latter are not only insensitive towards air and moisture, but they are also compatible with the formation of an ancillary stable N‐heterocyclic carbene moiety. As the oxyallyl pattern is proton‐responsive, it allows the reversible switching of the electronic properties of the carbene, as a ligand. 相似文献
4.
Vianney Guilly Boris Khasainov Henri-Noël Presles Daniel Desbordes 《Comptes Rendus Mecanique》2006,334(11):679-685
We present the results of numerical two-dimensional simulations of detonation cellular structures under non-monotonous heat release provided by a chemical reaction comprising two successive exothermic steps. The influence of the rate of the second step of chemical reaction on the detonation cellular structure has been investigated. Our simulations are the first that reproduce a cellular structure composed of two clearly distinct sets of cells with different characteristic sizes where fine cells completely fill up larger ones, as has been observed experimentally. To cite this article: V. Guilly et al., C. R. Mecanique 334 (2006). 相似文献
5.
Vianney O. Santos Isabela R. Leite Alexandre G. Brolo Joel C. Rubim 《Journal of Raman spectroscopy : JRS》2016,47(6):674-680
The electrochemical conversion of CO2 into value‐added products using room temperature ionic liquids as solvent/electrolyte has been proposed as an alternative to minimize the environmental effects of CO2 emissions. A key issue in the design of electrochemical systems for the reduction of CO2 is the in situ identification of intermediate surface species as well as reaction products. Copper electrodes, besides being used as cathodes in the electrochemical reduction of CO2, present surface‐enhanced Raman scattering (SERS) when properly activated. In this sense, the electrochemical reduction of CO2 over a copper electrode in the room temperature ionic liquids 1‐n‐butyl‐3‐methyl imidazolium tetrafluoroborate (BMI.BF4) was investigated by cyclic voltammetry and by in situ SERS. The cyclic voltammetries have shown that the presence of CO2 on the BMI.BF4 anticipates the reduction of BMI+ to the corresponding carbene. Fourier‐transform‐SERS spectra excited at 1064 nm and SERS spectra excited at 632.8 nm have shown vibrational signals from adsorbed CO. These SERS results indicated that CO adsorbs on the copper surface at two different surface sites. The observation of a 2275 cm−1 vibration in the SERS spectra also confirmed the presence of chemically adsorbed CO2. Other products of CO2 reduction in BMI.BF4, besides CO, were identified, including BMI carbene and the BMI‐CO2 adduct. The SERS results also suggest that the presence of a thin film of Cu2O on the copper surface anticipates the reduction of CO2 to CO, an important component of syngas. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
6.
Vianney Perchet 《Journal of Optimization Theory and Applications》2011,149(3):665-677
We provide a necessary and sufficient condition under which a convex set is approachable in a game with partial monitoring,
i.e. where players do not observe their opponents’ moves but receive random signals. This condition is an extension of Blackwell’s
Criterion in the full monitoring framework, where players observe at least their payoffs. When our condition is fulfilled,
we construct explicitly an approachability strategy, derived from a strategy satisfying some internal consistency property in an auxiliary game. 相似文献
7.
Swantje Mohr Dr. Jagannath Jana Yoanes Maria Vianney Prof. Dr. Klaus Weisz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(40):10437-10447
Canonical G-quadruplexes can adopt a variety of different topologies depending on the arrangement of propeller, lateral, or diagonal loops connecting the four G-columns. A novel intramolecular G-quadruplex structure is derived through inversion of the last G-tract of a three-layered parallel fold, associated with the transition of a single propeller into a lateral loop. The resulting (3+1) hybrid fold features three syn⋅anti⋅anti⋅anti G-tetrads with a 3’-terminal all-syn G-column. Although the ability of forming a duplex stem-loop between G-tracts seems beneficial for a propeller-to-lateral loop rearrangement, unmodified G-rich sequences resist folding into the new (3+1) topology. However, refolding can be driven by the incorporation of syn-favoring guanosine analogues into positions of the fourth G-stretch. The presented hybrid-type G-quadruplex structure as determined by NMR spectroscopy may provide for an additional scaffold in quadruplex-based technologies. 相似文献
8.
Vianney Aguilar-Vargas Jaime S. Valente Ignacio González 《Journal of Solid State Electrochemistry》2013,17(12):3145-3152
Two hydrotalcite-like compounds (HTs) were synthesized by coprecipitation. The electrochemical behavior of MgZnGa ([Mg0.58 Zn0.17Ga0.25 (OH)2] (CO3)2? 0.125 1.5 H2O) and ZnGaAl ([Zn0.75Ga0.19 Al0.06 (OH)2] (CO3)2? 0.125·1.5 H2O) Hydrotalcite-like compounds (HTs) was studied in NaOH at different concentrations. Voltammetric and chronoamperometric studies were performed to identify oxidation and reduction processes and the effect of the cations in total reactivity. Electrocatalytic effect of HTs on hydroxide electrochemical oxidation shows better performance of MgZnGa; this is apparently due to the presence of Mg and a greater amount of Ga3+ in the lattice of this HT. As far as reduction is concerned, Zn(II) reduction process is observed within the lattices of both HTs and is influenced by both the amount of OH? in the solution and the potential which the previous oxidation has been performed. 相似文献
9.
Yoanes Maria Vianney Prof. Dr. Klaus Weisz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(7):e202103718
Quadruplex-duplex (Q-D) junctions are increasingly considered promising targets for medicinal and technological applications. Here, a Q-D hybrid with a hairpin-type snapback loop coaxially stacked onto the quadruplex 3’-outer tetrad was designed and employed as a target structure for the indoloquinoline ligand SYUIQ-5. NMR spectral analysis demonstrated high-affinity binding of the ligand at the quadruplex-duplex interface with association constants determined by isothermal titration calorimetry of about 107 M−1 and large exothermicities ΔH° of −14 kcal/mol in a 120 mM K+ buffer at 40 °C. Determination of the ligand-bound hybrid structure revealed intercalation of SYUIQ-5 between 3’-outer tetrad and the neighboring CG base pair, maximizing π–π stacking as well as electrostatic interactions with guanine carbonyl groups in close vicinity to the positively charged protonated quinoline nitrogen of the tetracyclic indoloquinoline. Exhibiting considerable flexibility, the SYUIQ-5 sidechain resides in the duplex minor groove. Based on comparative binding studies with the non-substituted N5-methylated indoloquinoline cryptolepine, the sidechain is suggested to confer additional affinity and to fix the alignment of the intercalated indoloquinoline aromatic core. However, selectivity for the Q-D junction mostly relies on the geometry and charge distribution of the indoloquinoline ring system. The presented results are expected to provide valuable guidelines for the design of ligands specifically targeting Q-D interfaces. 相似文献
10.
Multiphase flows in porous media are encountered in several contexts—e.g., hydrocarbon recovery operations, battery electrodes, microfluidic devices, etc. Capillary-dominated flows are interesting due to the complex interplay of interfacial properties and pore geometries. Conventional hydrodynamic flow solvers are computationally inefficient in the capillary-dominated regime, particularly in complex pore structures. The algorithm developed here specifically targets this regime to reduce simulation times. We minimise the fluid–fluid and fluid–solid interaction energies through an approach inspired by the ferromagnetic Ising model. We validate the algorithm on (1) model pore geometries with analytical solutions for capillary action, and (2) rocks with available mercury porosimetry data. We validate its predictions for model geometries and sandstones using (1) curvatures calculated from theories developed by Mayer–Stowe–Princen, Ma and Morrow, and Mason and Morrow; (2) predictions from GeoDict, a commercial software package, which also includes a state-of-the-art drainage simulator; (3) mercury porosimetry data. Drainage capillary pressure curves predicted for Bentheimer and Fontainebleau rocks reasonably match porosimetry data. 相似文献