Vehicle and personnel routing optimization in the service sector: application to water distribution and treatment

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.      

One-dimensional quantum description of the bending vibrations of HCN/CNH for high values of the total angular momentum

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).     

Zur Kenntnis der Ortho-Strontiumphosphate

Zusammenfassung Die für den Einbau in die Calciumphosphate der Knochensubstanz in Frage kommenden Strontiumphosphate wurden auf ihre Existenzbedingungen untersucht. Oktacalciumphosphat tauscht in verd. Lösungen einige Prozente des Calciums gegen Strontium aus. Obwohl der Struktur nach apatitartige Strontiumphosphate zwischen Sr/P=1.33 und 1.67 erhältlich sind, läßt sich ein röntgenoptisch reines Strontiumoktaphosphat nicht isolieren, jedoch ein solches mit kleinem Carbonatgehalt und — leicht — die den Calciumsalzen analogen Strontiumphosphatcarbonate verschiedener Zusammensetzung. Im Hydrothermalbereich (375^o) sind je nach relativer Zusammensetzung des Strontiumphosphat-Systems SrHPO₄, Sr₂P₂O₇, Sr₂(PO₄)₂ und Sr₅(PO₄)₃OH stabil und gut kristallin erhältlich. Das Salz Sr₆H₃(PO₄)₅ läßt sich aus Lösungen von Strontiumphosphaten in Kohlensäure-Wasser, H₂S-Wasser und in einem Barbiturat-Puffersystem rein darstellen.

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Ortho strontium phosphates

Strontium phosphates which possibly are being incorporated into the calcium phosphates of bony tissue were investigated. Octacalcium phosphate in dilute solutions exchanges a few percent of calcium against strontium. While strontium phosphates with apatite-like structures, and with ratios of Sr/P between 1.33 and 1.67 can be prepared, no pure strontium octaphosphate, as a distinctive X-ray phase can be isolated. Only preparations with small amounts of carbonate, as well as strontium phosphate carbonates analogous to the corresponding calcium salts can be obtained. At hydrothermal conditions (375^o), the compounds SrHPO₄, Sr₂P₂O₇, Sr₃(PO₄)₂ and Sr₅(PO₄)₃OH are stable, and can be prepared in well cristallized form, depending on the relative composition of the strontium phosphate system. The salt Sr₆H₃(PO₄)₅ can be prepared in a pure state from solutions of strontium phosphates in aqueous solutions of carbonic acid, H₂S and barbiturate buffer systems.

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Herrn Prof. Dr. Dr. h. c.Hans Nowotny gewidmet.     

Fast 3D shape screening of large chemical databases through alignment-recycling

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.     

Das System Siliciumtetrafluorid—Trimethylamin in Lösung

Zusammenfassung Die Verbindung SiF₄·N(CH₃)₃ ist in Benzol löslich und daraus in nadelförmigen Kristallen erhältlich, während SiF₄·2 N(CH₃)₃ als in Petroläther schwer löslicher Niederschlag gewonnen werden kann. IR-Spektren beider Verbindungen werden mitgeteilt.Mit 2 Abbildungen     

2H Chemical-shift resolution and dipolar2H-1H,2H-15N correlations in solid-state MAS NMR spectroscopy for structure determination and distance measurements in hydrogen-bonded systems

In solid-state NMR, deuteron (²H) spectroscopy can be performed in full analogy to¹H spectroscopy, including²H chemical-shift resolution and²H-X dipolar correlation schemes, when the NMR experiments are conducted in a “rotor-synchronized” fashion under fast magic-angle spinning. Here, 2H-X NMR experiments of this type, including²H-¹⁵N and²H-¹H chemical-shift correlations and distance measurements, are introduced and demonstrated on cytosine monohydrate, whose acidic protons can readily be replaced by deuterons by recrystallization from D₂O. In this way,²H NMR spectroscopy provides information complementary to¹H NMR data, which is particularly useful for studying hydrogen bonds in supra- or biomolecular systems. Electronic supplementary material Supplementary material is available in the online versionof this article atand is accessible for authorized users.     

Photofragmentation of dichloromethanol Cl2CHOH along C-O and C-Cl cleavages: a theoretical study

Multireference configuration interaction calculations are carried out for ground and excited states of dichloromethanol, Cl2CHOH, to investigate two important photofragmentation processes relevant to atmospheric chemistry. Five low-lying excited states (1(1)A", 2(1)A', 1(3)A", 2(3)A" and 1(3)A') in the energy range between 6.4 and 7.5 eV are found to be highly repulsive for C-Cl elongation, leading to ClCHOH (X2A) and Cl (X2P). Photodissociation along the C-O bond resulting in CHCl2 (X2A') and OH (X2II) has to overcome a barrier of about 0.5 eV because the low-lying excited states 1(1)A", 1(3)A' and 1(3)A" become repulsive only after the C-O bond is elongated by about 0.3 A.     

Synthesis and properties of water-soluble gold colloids covalently derivatized with neutral polymer monolayers

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.     

Zur Röntgenfluoreszenzanalyse, 3. Mitt.: Die Änderung der relativen intensitäten der Kβ-Strahlung der Elemente Schwefel,Phosphor, Silicium und Aluminium bei Verbindungsbildung

Zusammenfassung Die Intensität der K-Strahlung von 27 Verbindungen der Elemente S, P. Si und Al wird mit der Intensität der K-Strahlung verglichen. Sie ist abhängig vom jeweiligen Element, von dessen Oxydationsstufe und vom Verbindungspartner. Für die Sauerstoffverbindungen ist die mit steigender Oxydationsstufe zunehmende Intensität des langwelligen Satelliten K' charakteristisch.Mit 4 Abbildungen     

Two-dimensional double-quantum 2H NMR spectroscopy in the solid state under OMAS conditions: correlating 2H chemical shifts with quasistatic line shapes.

Solid-state 2H NMR spectroscopy is a well-established and versatile method to study molecular orientation and dynamics in selectively deuterated samples. Herein, we introduce a 2D 2H double-quantum (DQ) NMR experiment performed under fast magic-angle spinning with a slight offset of the magic angle (OMAS). The experiment combines 2H chemical-shift resolution with DQ-filtered quasistatic 2H line shapes. In this way, it is possible to separate 2H resonances and to independently determine 2H quadrupole couplings at multiple sites. While 2H chemical shifts are resolved in the 2H DQ dimension, the quadrupole parameters can be obtained from characteristic line shapes which are reintroduced in the second dimension by the magic-angle offset. The 2D 2H DQ OMAS experiment is demonstrated on L-histidine which was deuterated at multiple sites by recrystallisation from D2O.