k—Very Ample Line Bundles on Del Pezzo Surfaces

A k-very ample line bundle L on a Del Pezzo Surface is numerically characterized, improving the results of Biancofiore— Ceresa in [7].     

Bestimmung geringer Mengen Phenol-2,4-disulfons?ure neben Phenol-4-sulfons?ure

Ohne Zusammenfassung

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Determination of minute amounts of phenol-2,4-disulphonic acid in the presence of phenol-4-sulphonic acid

     

Nachweis o- und p-substituierter Phenole

Zusammenfassung Bei halogen- oder alkylsubstituierten Phenolen kann man o- oder m-Isomere neben p-Isomeren dadurch nachweisen oder bestimmen, daß p-Isomere mit Diazoniumsalz in saurem Medium in Anwesenheit von Natriumacetat nicht oder nur sehr langsam kuppeln, aber o- und m-Isomere schnell. Die aus halogen- und alkylsubstituierten Phenolen mit diazotiertem p-Nitranilin entstandenen Tetrazoverbindungen sind Säure-Base-Indikatoren, die bei p-Isomeren mit Lauge rot bzw. rotviolett, aber bei m- und o-Isomeren orange werden. Damit kann man o- und p-Isomere unterscheiden.

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Summary In the case of halogen- or alkyl-substituted phenols, theo- andm-isomers can be detected or determined in the presence of thep-isomers through the finding that in acid medium thep-isomers do not couple at all or only very slowly in the presence of sodium acetate, whereaso- andm-isomers do so rapidly. The tetrazo compounds obtained from halogen- and alkyl-substituted phenols with diazotizedp-nitroaniline are acid-base indicators, that turn red or red-violet with bases in the case ofp-isomers but orange in the case ofo- andm-isomers. In this manner it is possible to distinguish betweeno- andp-isomers.

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Résumé Dans le cas des phénols halogéno ou alkylo substitués, on peut déceler ou doser les isomèreso etm en présence de para, car celui-ci ne se copule pas ou bien très lentement, avec le sel de diazonium en milieu acide en présence d'acétate de sodium, contrairement aux isomères o etm. Les composés tétrazoïques formés à partir des phénols substitués par des halogènes ou des radicaux alkylés avec lap-nitraniline diazotée, sont des indicateurs acide-base qui deviennent rouges à violet-rouge en présence de soude pour les isomères para mais orangés pour les isomères ortho et méta. On peut ainsi distinguer les isomères ortho et para.

     

Prolongement d'un courant négatif plurisousharmonique avec condition sur les tranches

In this Note, we prove a theorem on the extension of a negative (or positive) plurisubharmonic current T (i.e. such that $d{d}^{c}T?0$) with condition on the slices with respect to some coordinates. This theorem generalizes a result proved by El Mir–Ben Messaoud relative to d-closed positive currents with a condition on slices. The method consists first of proving a Chern–Levine–Nirenberg inequality for a positive (or negative) psh current, which is a generalization of results obtained by Bedford–Taylor, Demailly and Sibony for d-closed positive currents. Also we prove an Oka type inequality for positive psh currents, thereby generalizing former results by Ben Messaoud–El Mir concerning positive currents with a negative $d{d}^c$. To cite this article: M. Toujani, H. Ben Messaoud, C. R. Acad. Sci. Paris, Ser. I 339 (2004).     

In-beam γ spectroscopy using DIC with a radioactive Ne beam

A study of deep-inelastic and multi-nucleon transfer reactions to populate neutron-rich O, Ne and F nuclei is here presented. The reaction under analysis employed a beam of radioactive ²⁴Ne at 7.9 AMeV, provided by the SPIRAL facility at Ganil, impingin on a ²⁰⁸Pb target. The reaction products have been detected in the VAMOS spectrometer in coincidence with gamma rays measured by the EXOGAM array. Preliminary results here presented show a selectivity in the population of states of different nature.     

Phase separation and disorder in half metallic ferromagnetic manganite thin films: A theoretical study looking forward low noise nano-devices

The resistivity of thin La_0.7Sr_0.3MnO₃ films was first investigated in a wide temperature (T) range (10–750 K). Films grown by different techniques and on several substrates enabled to analyze samples with different amounts of disorder. The aim of this work was to elucidate the nature of the metal–insulator (M–I) transition occurring at T = T_p in these films and its relation with the different kinds of inhomogeneities they could present like intrinsic electric disorder and co-existence of two different electrical and/or magnetic phases. The low-temperature resistivity state was described mostly by a law which scales as T with  ≈ 2.5. This supports the theoretical proposal of single magnon scattering in presence of minority spin states localized by the disorder. In the whole range of temperatures the experimental data are found to be consistent with a phase separation (PS) scenario. In order to go through the origin of the characteristic length scale of inhomogeneity found, preliminarily low frequency noise measurements as a function of T in a range of temperature around the M–I transition were made. The samples used were patterned using photolithography into bridges with various widths and lengths. No clear sign of separation phase dynamic has been observed in our noise measurements. Unexpectedly the normalized Hooge parameter _H/n was found not to be volume (Ω) independent. The LSMO electrical properties may strongly be driven by disorder and new design for magnetoresistance sensors may have to take into account their intrinsic PS.     

16-Dimensional Smooth Projective Planes with Large Collineation Groups

Smooth projective planes are projective planes defined on smooth manifolds (i.e. the set of points and the set of lines are smooth manifolds) such that the geometric operations of join and intersection are smooth. A systematic study of such planes and of their collineation groups can be found in previous works of the author. We prove in this paper that a 16-dimensional smooth projective plane which admits a collineation group of dimension d 39 is isomorphic to the octonion projective plane P₂ O. For topological compact projective planes this is true if d 41. Note that there are nonclassical topological planes with a collineation group of dimension 40.     

Torsional splittings in the diode laser slit-jet spectra of the ν6 fundamental of 1-chloro-1,1-difluoroethane (HCFC-142b)

High resolution infrared spectra (0.001 cm⁻¹ FWHM) have been measured for mixtures of 1-chloro-1,1-difluoroethane in Ne, expanded in a supersonic planar jet. The ν₆ fundamental, infrared active with a dominant parallel transition moment, exhibits a remarkable splitting of about 0.035 cm⁻¹ for both ³⁵Cl and ³⁷Cl isotopomers. Several mechanisms of interaction of ν₆ with states with high torsional excitation are critically examined to explain the observed effect. It is concluded that the observed torsional splitting patterns can be explained in terms of a torsional Coriolis interaction between ν₆ and a highly excited torsional mode, 6ν₁₈. A full numerical analysis, performed including a torsional Coriolis term in the Hamiltonian, shows that the interaction mechanism requires a torsional barrier height of about 1270 cm⁻¹.     

Combinatorial synthesis of carbon nanotubes by the catalytic chemical vapor deposition method

Summary Bimetallic (Fe-Co) catalyst samples prepared from different precursors over various supports were tested in carbon nanotube (CNT) production. In order to quicken the evaluation of the performance of the catalysts a combinatorial arrangement was used.</o:p>     

Die Millon'sche Reaktion des Harns und ihre Beeinflussung durch Zufuhr von Tyrosin

Zusammenfassung Es werden einige Versuche an Kaninchen und Menschen über die Millon'sche Reaktion des Harns mitgeteilt. Ihre Intensität steigt an, wenn Tyrosin zugeführt wird, und zwar erheblich mehr nach dl-Tyrosin als nach l-Tyrosin. Ein Teil der Millon-Substanzen ist in Äther löslich, der ebenfalls nach der razemisierten stärker zunimmt als der nach der natürlichen Aminosäure.