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1.
Verdecho María-José Alarcón-Valero Faustino Pérez-Perales David Alfaro-Saiz Juan-José Rodríguez-Rodríguez Raúl 《Central European Journal of Operations Research》2021,29(4):1231-1251
Central European Journal of Operations Research - Sustainability practice within supply chains remains in an early development phase. Enterprises still need tools that support the integration of... 相似文献
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David E. Delgado Lauren F. Sturdy Craig W. Burkhart Kenneth R. Shull 《Journal of Polymer Science.Polymer Physics》2019,57(18):1246-1254
The utility of the quartz crystal microbalance (QCM) as a high‐frequency rheometer operating at 15 MHz was demonstrated. High‐frequency data obtained from a series of rubbery materials were compared with results obtained from traditional dynamic mechanical analysis (DMA) at much lower frequencies. The high‐frequency data enable meaningful shift factors to be obtained at temperatures much further above glass‐transition temperature (T g) than would otherwise be possible, giving a more complete picture of the temperature dependence of the viscoelastic properties. The QCM can also be used to quantify mass uptake and changes in viscoelastic properties during sample oxidation. The viscoelastic response spanning the full range of behaviors from the rubber to glassy regimes was found to fit well with a six‐element model consisting of three power‐law springpot elements. One of these elements is particularly sensitive to the behavior in the transition regime where the phase angle is maximized. The value of this quantity is obtained from the maximum phase angle, which can be obtained from a temperature sweep at fixed frequency, proving a means for more detailed frequency‐dependent rheometric information to be obtained from a fixed‐frequency measurement at a range of temperatures. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1246–1254 相似文献
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Luis Gutiérrez-Arzaluz David Ignacio Ramírez-Palma Lillian G. Ramírez-Palma Prof. Dr. José Enrique Barquera-Lozada Prof. Dr. Jorge Peon Prof. Dr. Fernando Cortés-Guzmán 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(3):775-784
Copper(I) complexes (CICs) are of great interest due to their applications as redox mediators and molecular switches. CICs present drastic geometrical change in their excited states, which interferes with their luminescence properties. The photophysical process has been extensively studied by several time-resolved methods to gain an understanding of the dynamics and mechanism of the torsion, which has been explained in terms of a Jahn–Teller effect. Here, we propose an alternative explanation for the photoinduced structural change of CICs, based on electron density redistribution. After photoexcitation of a CIC (S0→S1), a metal-to-ligand charge transfer stabilizes the ligand and destabilizes the metal. A subsequent electron transfer, through an intersystem crossing process, followed by an internal conversion (S1→T2→T1), intensifies the energetic differences between the metal and ligand within the complex. The energy profile of each state is the result of the balance between metal and ligand energy changes. The loss of electrons originates an increase in the attractive potential energy within the copper basin, which is not compensated by the associated reduction of the repulsive atomic potential. To counterbalance the atomic destabilization, the valence shell of the copper center is polarized (defined by ∇2ρ(r) and ∇2Vne(r)) during the deactivation path. This polarization increases the magnitude of the intra-atomic nuclear–electron interactions within the copper atom and provokes the flattening of the structure to obtain the geometry with the maximum interaction between the charge depletions of the metal and the charge concentrations of the ligand. 相似文献
5.
Guillaume Erbland Dr. Seifallah Abid Yohan Gisbert Nathalie Saffon-Merceron Yuichiro Hashimoto Leonardo Andreoni Théo Guérin Dr. Claire Kammerer Prof. Dr. Gwénaël Rapenne 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(71):16328-16339
The design and synthesis of two families of molecular-gear prototypes is reported, with the aim of assembling them into trains of gears on a surface and ultimately achieving controlled intermolecular gearing motion. These piano-stool ruthenium complexes incorporate a hydrotris(indazolyl)borate moiety as tripodal rotation axle and a pentaarylcyclopentadienyl ligand as star-shaped cogwheel, equipped with five teeth ranging from pseudo-1D aryl groups to large planar 2D paddles. A divergent synthetic approach was followed, starting from a pentakis(p-bromophenyl)cyclopentadienyl ruthenium(II) complex as key precursor or from its iodinated counterpart, obtained by copper-catalyzed aromatic Br/I exchange. Subsequent fivefold cross-coupling reactions with various partners allowed high structural diversity to be reached and yielded molecular-gear prototypes with aryl-, carbazole-, BODIPY- and porphyrin-derived teeth of increasing size and length. 相似文献
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Journal of Optimization Theory and Applications - In an earlier analysis of strong variation algorithms for optimal control problems with endpoint inequality constraints, Mayne and Polak provided... 相似文献
7.
Kielas-Jensen Calvin Cichella Venanzio Casbeer David Manyam Satyanarayana Gupta Weintraub Isaac 《Journal of Optimization Theory and Applications》2021,191(2-3):899-916
Journal of Optimization Theory and Applications - A framework for monitoring a target modeled as Dubins car using multiple UAVs is proposed. The UAVs are subject to minimum and maximum speed,... 相似文献
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Amit Kumar Trevor Janes Subrata Chakraborty Prosenjit Daw Niklas vonWolff Raanan Carmieli Yael Diskin‐Posner David Milstein 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(11):3411-3415
We report a C?C bond‐forming reaction between benzyl alcohols and alkynes in the presence of a catalytic amount of KOtBu to form α‐alkylated ketones in which the C=O group is located on the side derived from the alcohol. The reaction proceeds under thermal conditions (125 °C) and produces no waste, making the reaction highly atom efficient, environmentally benign, and sustainable. Based on our mechanistic investigations, we propose that the reaction proceeds through radical pathways. 相似文献
10.
Dr. Safaa M. Kishk Dr. Kirsty J. McLean Dr. Sakshi Sood Darren Smith Jack W.D. Evans Prof. Mohamed A. Helal Prof. Mohamed S. Gomaa Prof. Ismail Salama Prof. Samia M. Mostafa Dr. Luiz Pedro S. de Carvalho Colin W. Levy Prof. Andrew W. Munro Dr. Claire Simons 《ChemistryOpen》2019,8(7):995-1011
The emergence of untreatable drug-resistant strains of Mycobacterium tuberculosis is a major public health problem worldwide, and the identification of new efficient treatments is urgently needed. Mycobacterium tuberculosis cytochrome P450 CYP121A1 is a promising drug target for the treatment of tuberculosis owing to its essential role in mycobacterial growth. Using a rational approach, which includes molecular modelling studies, three series of azole pyrazole derivatives were designed through two synthetic pathways. The synthesized compounds were biologically evaluated for their inhibitory activity towards M. tuberculosis and their protein binding affinity (KD). Series 3 biarylpyrazole imidazole derivatives were the most effective with the isobutyl ( 10 f ) and tert-butyl ( 10 g ) compounds displaying optimal activity (MIC 1.562 μg/mL, KD 0.22 μM ( 10 f ) and 4.81 μM ( 10 g )). The spectroscopic data showed that all the synthesised compounds produced a type II red shift of the heme Soret band indicating either direct binding to heme iron or (where less extensive Soret shifts are observed) putative indirect binding via an interstitial water molecule. Evaluation of biological and physicochemical properties identified the following as requirements for activity: LogP >4, H-bond acceptors/H-bond donors 4/0, number of rotatable bonds 5–6, molecular volume >340 Å3, topological polar surface area <40 Å2. 相似文献