Heuristic solutions to the problem of routing school buses with multiple objectives

2002

In this paper we address the problem of routing school buses in a rural area. We approach this problem with a node routing model with multiple objectives that arise from conflicting viewpoints. From the point of view of cost, it is desirable to minimise the number of buses used to transport students from their homes to school and back. From the point of view of service, it is desirable to minimise the time that a given student spends en route. The current literature deals primarily with single-objective problems and the models with multiple objectives typically employ a weighted function to combine the objectives into a single one. We develop a solution procedure that considers each objecti…

Tandem β-Boration/Arylation of α,β-Unsaturated Carbonyl Compounds by Using a Single Palladium Complex To Catalyse Both Steps

2010

Diphenyl(3-methyl-2-indolyl)phosphine (C(9)H(8)NPPh(2), 1) gives stable dimeric palladium(II) complexes that contain the phosphine in P,N-bridging coordination mode. On treating 1 with [Pd(O(2)CCH(3))(2)], the new complexes [Pd(mu-C(9)H(7)NPPh(2))(NCCH(3))](2) (2) or [Pd(mu-C(9)H(7)NPPh(2))(mu-O(2)CCH(3))](2) (3) were isolated, depending on the solvent used, acetonitrile or toluene, respectively. Further reaction of 3 with the ammonium salt of 1 led to the substitution of one carboxylate ligand to afford [Pd(mu-C(9)H(7)NPPh(2))(3)(mu-O(2)CCH(3))] (4), in which the bimetallic unit is bonded by three C(9)H(7)NPPh(2)(-) moieties and one carboxylate group. Using this methodology, [Pd(2)(mu-C(6)…

Unprecedented use of silver(I) N-heterocyclic carbene complexes for the catalytic preparation of 1,2-bis(boronate) esters.

2005

Catalytic diboration of internal and terminal alkenes with Ag(I) N-heterocyclic carbene complexes leads to 1,2-bis(boronate) esters as single intermediates, that can be oxidised towards the corresponding diols. Sanau Torrecilla, Mercedes, Mercedes.Sanau@uv.es

Multifaceted Palladium Catalysts Towards the Tandem Diboration-Arylation Reactions of Alkenes

2008

Novel Pd(2) (6+) compounds have been synthesized in high yield. These compounds and their Pd(2) (4+) counterparts as synthetic precursors mediate the diboration of vinylarenes and aliphatic 1-alkenes, and under mild and basic reaction conditions they produce a variety of 1,2-diboronate esters with excellent conversions and chemoselectivities. The presence of bis(catecholato)diboron (B(2)cat(2)) favours the reduction of Pd(III) to Pd(II), while the catalytic precursor of Pd(II) is transformed into Pd(0)-nanoparticles. An "in situ" catalytic tandem reaction has been designed to transform the diboronate intermediates into the monoarylated product, which after oxidative workup, provides the car…

Nuclear Localization of PTEN by a Ran-dependent Mechanism Enhances Apoptosis: Involvement of an N-Terminal Nuclear Localization Domain and Multiple N…

2006

The targeting of the tumor suppressor PTEN protein to distinct subcellular compartments is a major regulatory mechanism of PTEN function, by controlling its access to substrates and effector proteins. Here, we investigated the molecular basis and functional consequences of PTEN nuclear/cytoplasmic distribution. PTEN accumulated in the nucleus of cells treated with apoptotic stimuli. Nuclear accumulation of PTEN was enhanced by mutations targeting motifs in distinct PTEN domains, and it was dependent on an N-terminal nuclear localization domain. Coexpression of a dominant negative Ran GTPase protein blocked PTEN accumulation in the nucleus, which was also affected by coexpression of importin…

Gold(0) Nanoparticles for Selective Catalytic Diboration

2008

ChemInform Abstract: Multifaceted Palladium Catalysts Towards the Tandem Diboration-Arylation Reactions of Alkenes.

2009

Novel Pd(2) (6+) compounds have been synthesized in high yield. These compounds and their Pd(2) (4+) counterparts as synthetic precursors mediate the diboration of vinylarenes and aliphatic 1-alkenes, and under mild and basic reaction conditions they produce a variety of 1,2-diboronate esters with excellent conversions and chemoselectivities. The presence of bis(catecholato)diboron (B(2)cat(2)) favours the reduction of Pd(III) to Pd(II), while the catalytic precursor of Pd(II) is transformed into Pd(0)-nanoparticles. An "in situ" catalytic tandem reaction has been designed to transform the diboronate intermediates into the monoarylated product, which after oxidative workup, provides the car…

The Steiner Traveling Salesman Problem and its extensions

2019

Abstract This paper considers the Steiner Traveling Salesman Problem, an extension of the classical Traveling Salesman Problem on an incomplete graph where not all vertices have demand. Some extensions including several depots or location decisions are introduced, modeled and solved. A compact integer linear programming formulation is proposed for each problem, where the routes are represented with two-index decision variables, and parity conditions are modeled using cocircuit inequalities. Exact branch-and-cut algorithms are developed for all formulations. Computational results obtained confirm the good performance of the algorithms. Instances with up to 500 vertices are solved optimally.

Dinuclear Ortho-Metalated Palladium(II) Compounds with N,N- and N,O-Donor Bridging Ligands. Synthesis of New Palladium(III) Complexes

2011

New dinuclear ortho-metalated palladium(II) compounds with N,N′-diarylformamidinates, Pd2[(C6H4)PPh2]2[R′NC(H)NR′]2 (R′ = C6H5, 3a; R′ = p-CH3C6H4, 3b; R′ = p-CH3OC6H4, 3c) and N,O-donor ligands, Pd2[(C6H4)PPh2]2[N,O]2 (N,O = succinimidate (5), phtalimidate (6), 2-hydroxypyridinate (7), acetanilidate (8)) have been synthesized and characterized by NMR spectroscopy and X-ray diffraction methods. The oxidation with iodobenzene dichloride gave new and rare Pd26+ compounds, Pd2[(C6H4)PPh2]2[R′NC(H)NR′]2Cl2 (R′ = C6H5, 4a; R′ = p-CH3C6H4, 4b). DFT calculations on the Pd24+ → Pd26+ oxidation reaction show that the substituents on the amidinate N atoms have a greater effect on the reaction energy …

The Windy clustered prize-collecting arc-routing problem

2011

This paper introduces the windy clustered prize-collecting arc-routing problem. It is an arc-routing problem where each demand edge is associated with a profit that is collected once if the edge is serviced, independent of the number of times the edge is traversed. It is further required that if a demand edge is serviced, then all the demand edges of its component are also serviced. A mathematical programming formulation is given and some polyhedral results including several facet-defining and valid inequalities are presented. The separation problem for the different families of inequalities is studied. Numerical results from computational experiments are analyzed. © 2011 INFORMS.