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1.
The binding of heterobidentate P∧S ligands introduces metal-centered chirality to the planar chiral parent complex Ru(η6:η1-NMe2C6H4C6H4PCy2)Cl2. Observed diastereomeric ratios for the kinetic product vary dramatically depending upon ring size of the chelate formed with the P∧S ligand. The complexes epimerize very slowly to thermodynamic product ratios that are substantially different from the kinetic product ratios. 相似文献
2.
Fabien Tricoire 《4OR: A Quarterly Journal of Operations Research》2007,5(2):165-168
We present an overview of the author’s Ph.D. thesis, supervised by P. Dejax and N. Bostel, which was defended in February
2006 at école des Mines de Nantes, France. The thesis is written in French, and is available at . It was conducted in the context of a research contract with a water distribution company. In a first section, we define
multiperiod routing problems for service technicians. In a second section, we present some heuristics and a memetic algorithm
used to solve these problems. The third section introduces optimal and near-optimal approaches based on column generation.
Finally, we present some applications to the real-life case. The methods presented in Sects. 2, 3 and 4 were tested over several
sets of problems, based on real-life statistics provided by the company.
相似文献
3.
4.
Justum Y Gatti F Lauvergnat D Nauts A Chapuisat X 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2002,58(4):649-661
For high values of the quantum number of the total angular momentum J (up to J = 20), quantum mechanical eigenstates (eigenvalues and eigenfunctions) are calculated by the method of Gatti et al. (J. Mol. Spectrosc. 181 (1997) 403) for the bending deformations of HCN and CNH. In particular, we have examined the l-type resonances in highly excited rovibrational states within the framework of a one-dimensional model, i.e. along the reaction pathway for the isomerization reaction HCN/CNH. The potential energy surface used is that of Bowman et al. (J. Chem. Phys. 99 (1993) 308). 相似文献
5.
Fabien Fontaine Evan Bolton Yulia Borodina Stephen H Bryant 《Chemistry Central journal》2007,1(1):12-14
Background
Large chemical databases require fast, efficient, and simple ways of looking for similar structures. Although such tasks are now fairly well resolved for graph-based similarity queries, they remain an issue for 3D approaches, particularly for those based on 3D shape overlays. Inspired by a recent technique developed to compare molecular shapes, we designed a hybrid methodology, alignment-recycling, that enables efficient retrieval and alignment of structures with similar 3D shapes. 相似文献6.
Vanderperren H Van Wouwe N Behets S Windal I Van Overmeire I Fontaine A 《Talanta》2004,63(5):1277-1280
Polyhalogenated aromatic hydrocarbons, such as polychlorinated dibenzo-p-dioxins are a large and diverse group of environmental pollutants. Their tendency to accumulate in the food chain and their toxicity make monitoring necessary. The reference analysis method is laborious and very expensive, therefore cheap and rapid bioassays have been developed. The chemical-activated luciferase bioassay (CALUX) bioassay uses a recombinant cell line, which responds to dioxins and dioxin-like molecules with Ah receptor (AhR)-dependent induction of firefly luciferase in a dose related response. The CALUX was tested for its use in the screening of feed. Aliquots of 20 g of enriched feed were extracted with a toluene:methanol mixture (20:4 v/v) and extracts were defatted on 33% H2SO4 silica columns and purified on carbon columns. Only the dioxin and furan fraction was analysed, the PCB fraction was discarded. The precision of the method is acceptable and in compliance with an R.S.D. <30% as suggested for cell-based bioassays in the Commission Directive 2002/70/EC of July 2002. The results evidence good agreement between TEQ-values obtained by either CALUX or GC–HRMS. The method is now routinely in use for a feed screening programme designed by the Federal Agency for the Safety of the Food chain. Approximately, 25 samples are analysed weekly. From the obtained results approximately 10% was confirmed by GC–HRMS. The false positive ratio is 1% and no false negatives were found, making the use of the CALUX technology advantageous. 相似文献
7.
Vincent Lapinte Laurent Fontaine Vronique Montembault Irne Campistron Danile Reyx 《Journal of molecular catalysis. A, Chemical》2002,190(1-2):117-129
ROMP and retro-acyclic diene metathesis (ADMET) were used for the synthesis of new functional polymers and functional oligomers, respectively. Purely exo and enantiomerically pure norbornene and 7-oxanorbornene derivatives were prepared using stereospecific synthesis, effective fractionation and high yield condensation reactions. Successful ROMPs of those monomers were performed using either the new carbenic Schrock’s or Grubb’s catalysts or in some cases a classical bicomponent catalyst. New functional polymers such as optically active poly(norbornene-2-carboxylic acid), reactive poly(norbornene-2-azlactone), and side-chain liquid crystal polyoxanorbornenes were fully characterized. On the other hand, successful depolymerizations of 1,4-polyisoprene and of epoxidized 1,4-polybutadiene via cross-metathesis with 4-octene were performed using a stabilized bicomponent catalyst and the Grubb’s catalyst, respectively. Conditions for the controlled synthesis of epoxidized oligobutadienes and of epoxydienic monomers via retro-ADMET were clearly defined. 相似文献
8.
The quantum yields of thecis trans andtrans cis Hg 6(3P1) photosensitized isomerizations of 1,3-pentadiene at 100 Torr and 22°C are 0.54±0.02 and 0.42±0.02, respectively. The steady state ratio ([trans]/[cis])ss is 1.27±0.05 which is almost identical with the ratio of the quantum yields, (ct)/(tc)=1.29±0.10. Thecistrans isomerization is suggested as a useful actinometer for mercury sensitized reactions.
Hg 6(3P1) 1,3- 100 22°C 0,54±0,02 0,42±0,02, . ([]/[]) 1,27±0,05, ( )/( )=1,29±0,10. , .相似文献
9.
Mangeney C Ferrage F Aujard I Marchi-Artzner V Jullien L Ouari O Rékaï el D Laschewsky A Vikholm I Sadowski JW 《Journal of the American Chemical Society》2002,124(20):5811-5821
Citrate-capped gold nanoparticles as well as planar gold surfaces can be efficiently grafted with a covalently attached polymer monolayer a few nanometers thick, by simple contact of the metal surface with dilute aqueous solutions of hydrophilic polymers that are end-capped with disulfide moieties, as shown by UV/vis absorption, dynamic light scattering, and surface plasmon resonance studies. The hydrophilic polymer-coated gold colloids can be freeze-dried and stored as powders that can be subsequently dissolved to yield stable aqueous dispersions, even at very large concentrations. They allow for applying filtrations, gel permeation chromatography, or centrifugation. They do not suffer from undesirable nonspecific adsorption of proteins while allowing the diffusion of small species within the hydrogel surface coating. In addition, specific properties of the original hydrophilic polymers are retained such as a lower critical solution temperature. The latter feature could be useful to enhance optical responses of functionalized gold surfaces toward interaction with various substrates. 相似文献
10.