Solvay

About: Solvay is a company organization based out in Brussels, Belgium. It is known for research contribution in the topics: Catalysis & Polymer. The organization has 6083 authors who have published 7004 publications receiving 105745 citations.

All-order differential equations for one-loop closed-string integrals and modular graph forms

Abstract: We investigate generating functions for the integrals over world-sheet tori appearing in closed-string one-loop amplitudes of bosonic, heterotic and type-II theories. These closed-string integrals are shown to obey homogeneous and linear differential equations in the modular parameter of the torus. We spell out the first-order Cauchy-Riemann and second-order Laplace equations for the generating functions for any number of external states. The low-energy expansion of such torus integrals introduces infinite families of non-holomorphic modular forms known as modular graph forms. Our results generate homogeneous first- and second-order differential equations for arbitrary such modular graph forms and can be viewed as a step towards all-order low-energy expansions of closed-string integrals.

Process for producing an organic compound

Abstract: Process for producing a chlorohydrin by reaction between a multihydroxylated-aliphatic hydrocarbon, an ester of a multihydroxylated-aliphatic hydrocarbon, or a mixture thereof, and a chlorinating agent, according to which the multihydroxylated-aliphatic hydrocarbon, the ester of a multihydroxylated-aliphatic hydrocarbon, or the mixture thereof used contains at least one solid or dissolved metal salt, the process comprising a separation operation to remove at least part of the metal salt.

Process for the polymerization of alpha-olefins

Abstract: POLYMERIZATION OF A-OLEFINS IS CARRIED OUT IN THE PRESENCE OF A SOLID CATALYST WHICH IS COMPOSED OF AN ORGANIC COMPOUND OF A METAL OF GROUPS I TO III OF THE PERIODIC TABLE AND A CRYSTALLINE HALIDE OF A REDUCED METAL OF GROUPS IVB, VB OR VIB OF THE PERIODIC TABLE DEPOSITED ON A PULVERULENT SUPPORT. THE REDUCED METAL HALIDE IS OBTAINED BY REDUCING A HALIDE OF THE METAL AT ITS MAXIMUM VALENCE WTH AN ORGANOMETALLIC COMPOUND AT A TEMPERATURE BELOW 0*C. AND IN THE ABSENCE OF LIQUID DILUENT WHEREIN THE HALIDE OF THE METAL AT ITS MAXIMUM VALENCE OR THE ORGANOMETALLIC COMPOUND HAS BEEN ABSORBED ON A SOLID PULVERULENT SUPPORT PRIOR TO THE REDUCTION. CATALYSTS PREPARED IN THIS MANNER HAVE A HIGH STEREOSPECIFICITY AND CATALYST ACTIVITY, AND POLYMERIZATION CARRIED OUT IN THE PRESENCE THEREOF YIELDS HIGHLY ISOTACTIC CRYSTALLINE POLYMER.

Process for extracting poly-beta-hydroxybutyrates by means of a solvent from an aqueous suspension of microorganisms

Abstract: A process for extracting poly-beta-hydroxybutyrates from an aqueous suspension of microorganisms, in which an azeotropic distillation, and an extraction of the polymer by means of the solvent used, are carried out simultaneously. The poly-beta-hydroxybutyrates obtained can be used in medicine.

Investigation into the surface selective oxidation of dual-phase steels by XPS, SAM and SIMS

Abstract: Surface selective oxides created during continuous annealing (MnO, SiO2, etc.) can have a deleterious effect on coating adhesion after hot-dip galvanizing. Earlier research works have made it clear that increasing the annealing atmosphere oxidizing potential can alleviate the problem by reducing external surface selective oxidation. In the present study, increasing the water vapour content of the nitrogen–hydrogen protective gas mixture was used to raise its oxidizing potential. The technique was applied to a classical dual-phase steel (0.15% C, 1.5% Mn, 0.45% Si, 0.05% Al…) that was annealed for 60 s at 800–810°C in protective atmospheres of nitrogen and 5% hydrogen with water vapour contents ranging from 10 to 6000 ppm. Post-annealing surfaces were characterized by x-ray photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS) and scanning Auger microscopy (SAM). In situ XPS analyses were carried out right after simulation annealing in the preparation chamber connected to the spectrometer, never returning the specimens to air. This made it possible to identify in a reliable way the elements that segregated to the surface during the treatment, and to determine their corresponding oxidation states. On the other hand, the high sensitivity of SIMS was taken advantage of to assess oxide in-depth concentration profiles (SiO2, Al2O3, FeO) as a function of the annealing conditions, and SAM was used to characterize the corresponding oxide particle morphology. External selective oxidation was thus shown to decrease with increasing water vapour contents in the atmosphere (from 80 to 6000 ppm), whereas internal oxidation increases drastically to ∼4 μm below the free surface. At 10 ppm of H2O the oxygen partial pressure is very low and the external selective oxidation results in a thin, but almost complete, coverage of the steel surface. Consequently, metallic iron cannot be observed at the surface, thus hampering hot-dip galvanizability, unless the water vapour content is raised to 6000 ppm. Various surface morphologies were observed and discussed. In the authors' opinion, basic investigations of this type are an indispensable first step to improving the response of highly alloyed steels (dual-phase, TRIP) to hot-dip galvanizing. Copyright © 2003 John Wiley & Sons, Ltd.