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101.
Sauleh Siddiqui Steven A Gabriel Shapour Azarm 《The Journal of the Operational Research Society》2015,66(4):664-673
Uncertainty and integer variables often exist together in economics and engineering design problems. The goal of robust optimization problems is to find an optimal solution that has acceptable sensitivity with respect to uncertain factors. Including integer variables with or without uncertainty can lead to formulations that are computationally expensive to solve. Previous approaches for robust optimization problems under interval uncertainty involve nested optimization or are not applicable to mixed-integer problems where the objective or constraint functions are neither quadratic, nor linear. The overall objective in this paper is to present an efficient robust optimization method that does not contain nested optimization and is applicable to mixed-integer problems with quasiconvex constraints (? type) and convex objective funtion. The proposed method is applied to a variety of numerical examples to test its applicability and numerical evidence is provided for convergence in general as well as some theoretical results for problems with linear constraints. 相似文献
102.
Homogeneous and unimolecular gas‐phase thermal decomposition kinetics of methyl benzoylformate: experimental and theoretical study 下载免费PDF全文
Yeljair Monascal Alexis Maldonado José R. Mora Tania Córdova Gabriel Chuchani 《Journal of Physical Organic Chemistry》2015,28(1):40-46
The kinetics of the gas‐phase thermal decomposition of the α‐ketoester methyl benzoylformate was carried out in a static system with reaction vessel deactivated with allyl bromide, and in the presence of the free radical inhibitor propene. The rate coefficients were determined over the temperature range of 440–481 °C and pressures from 32 to 80 Torr. The reaction was found to be homogenous, unimolecular and obey a first‐order rate law. The products are methyl benzoate and CO. The temperature dependence of the rate coefficient gives the following Arrhenius parameters: log10 k (s?1) = 13.56 ± 0.31 and Ea (kJ mol?1) = 232.6 ± 4.4. Theoretical calculations of the kinetic and thermodynamic parameters are in good agreement with the experimental values using PBE1PBE/6‐311++g(d,p). A theoretical Arrhenius plot was constructed at this level of theory, and the good agreement with the experimental Arrhenius plot suggests that this model of transition state may describe reasonably the elimination process. These results suggest a concerted non‐synchronous semi‐polar three‐membered cyclic transition state type of mechanism. The most advanced coordinate is the bond breaking Cδ+‐‐‐δ‐OCH3 with an evolution of 66.7%, implying this as the limiting factor of the elimination process. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
103.
Gas‐phase elimination kinetics of selected aliphatic α,β‐unsaturated aldehydes catalyzed by hydrogen chloride 下载免费PDF全文
Libia L. Julio José R. Mora Alexis Maldonado Gabriel Chuchani 《Journal of Physical Organic Chemistry》2015,28(4):261-265
The gas‐phase elimination of 2‐methyl‐2‐propenal catalyzed by HCl yields propene and CO gas, while E‐2‐pentenal with the same catalyst gives butene and CO gas. The kinetics determinations were carried out in a static system with the reaction vessels deactivated with allyl bromide and the presence of the free radical inhibitor toluene. Temperature and pressure ranges were 350.0–410.0 °C and 34–76 Torr. The elimination reactions are homogeneous and unimolecular, and follow a first‐order rate law. The rate coefficients for the reactions are expressible by the following Arrhenius equations: Data from the kinetic and thermodynamic parameters of these catalyzed elimination reactions implies a mechanism of a concerted five‐membered cyclic transition state structure for the formation of the corresponding olefin and carbon monoxide. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
104.
Back Cover: Exploring Excited‐State Tunability in Luminescent Tris‐cyclometalated Platinum(IV) Complexes: Synthesis of Heteroleptic Derivatives and Computational Calculations (Chem. Eur. J. 52/2014) 下载免费PDF全文
105.
Stereospecific Formal [3+2] Dipolar Cycloaddition of Cyclopropanes with Nitrosoarenes: An Approach to Isoxazolidines 下载免费PDF全文
Shyamal Chakrabarty Dr. Indranil Chatterjee Birgit Wibbeling Dr. Constantin Gabriel Daniliuc Prof. Dr. Armido Studer 《Angewandte Chemie (International ed. in English)》2014,53(23):5964-5968
The MgBr2‐catalyzed formal [3+2] cycloaddition of donor–acceptor activated cyclopropanes with nitrosoarenes offers a novel approach to various structurally diverse isoxazolidines. The reactions, which are experimentally easy to conduct, occur with complete stereospecificity and perfect control of regioselectivity. Product isoxazolidines can be readily transformed into α‐amino lactones by reductive or decarboxylative N? O cleavage and subsequent lactonisation, and the N‐aryl bond cleavage is also possible under oxidative conditions. 相似文献
106.
Nucleation and Growth Synthesis of Siloxane Gels to Form Functional,Monodisperse, and Acoustically Programmable Particles 下载免费PDF全文
C. Wyatt Shields IV Danping Sun Dr. Kennita A. Johnson Korine A. Duval Aura V. Rodriguez Dr. Lu Gao Prof. Paul A. Dayton Prof. Gabriel P. López 《Angewandte Chemie (International ed. in English)》2014,53(31):8070-8073
Nucleation and growth methods offer scalable means of synthesizing colloidal particles with precisely specified size for applications in chemical research, industry, and medicine. These methods have been used to prepare a class of silicone gel particles that display a range of programmable properties and narrow size distributions. The acoustic contrast factor of these particles in water is estimated and can be tuned such that the particles undergo acoustophoresis to either the pressure nodes or antinodes of acoustic standing waves. These particles can be synthesized to display surface functional groups that can be covalently modified for a range of bioanalytical and acoustophoretic sorting applications. 相似文献
107.
Molecular Salt Effects in the Gas Phase: Tuning the Kinetic Basicity of [HCCLiCl]− and [HCCMgCl2]− by LiCl and MgCl2 下载免费PDF全文
Dr. George N. Khairallah Dr. Gabriel da Silva Prof. Richard A. J. O'Hair 《Angewandte Chemie (International ed. in English)》2014,53(41):10979-10983
A combination of gas‐phase ion–molecule reaction experiments and theoretical kinetic modeling is used to examine how a salt can influence the kinetic basicity of organometallates reacting with water. [HC?CLiCl]? reacts with water more rapidly than [HC?CMgCl2]?, consistent with the higher reactivity of organolithium versus organomagnesium reagents. Addition of LiCl to [HC?CLiCl]? or [HC?CMgCl2]? enhances their reactivity towards water by a factor of about 2, while addition of MgCl2 to [HC?CMgCl2]? enhances its reactivity by a factor of about 4. Ab initio calculations coupled with master equation/RRKM theory kinetic modeling show that these reactions proceed via a mechanism involving formation of a water adduct followed by rearrangement, proton transfer, and acetylene elimination as either discrete or concerted steps. Both the energy and entropy requirements for these elementary steps need to be considered in order to explain the observed kinetics. 相似文献
108.
Inside Back Cover: Molecular Salt Effects in the Gas Phase: Tuning the Kinetic Basicity of [HCCLiCl]− and [HCCMgCl2]− by LiCl and MgCl2 (Angew. Chem. Int. Ed. 41/2014) 下载免费PDF全文
109.
Sudip Pan Diego Moreno Dr. José Luis Cabellos Prof. Gabriel Merino Prof. Pratim K. Chattaraj 《Chemphyschem》2014,15(12):2618-2625
The global minima of Be2N2, Be3N2 and BeSiN2 clusters are identified using a modified stochastic kick methodology. The structure, stability and bonding nature of these clusters bound to noble gas (Ng) atoms are studied at the MP2/def2‐QZVPPD level of theory. Positive Be?Ng bond dissociation energy, which gradually increases down Group 18 from He to Rn, indicates the bound nature of Ng atoms. All of the Ng‐binding processes are exothermic in nature. The Xe and Rn binding to Be2N2 and Be3N2 clusters and Ar?Rn binding to BeSiN2 are exergonic processes at room temperature; however, for the lighter Ng atoms, lower temperatures are needed. Natural population analysis, Wiberg bond index computations, electron density analysis, and energy decomposition analysis are performed to better understand the nature of Be?Ng bonds. 相似文献
110.