Showing papers by "University of Rennes published in 1983"
TL;DR: A general chemoselective method for the reduction of azides into primary amines was described in this article, where the reduction was carried out by using a general method for azides.
237 citations
193 citations
TL;DR: In this article, the central part of the Aar Granite (Aar Valley) shows lens-shaped domains of low strain separated by anastomosing domains of high strain.
171 citations
132 citations
TL;DR: In this paper, the authors show that the grey gneisses have most likely been derived by partial melting of short-lived basaltic crustal material (garnet-bearing amphibolite), which was separated from a mantle source no more than 150 Ma before the melting.
114 citations
TL;DR: A submersible study of a fast spreading (12 cm yr-1) mid-Ocean ridge segment (East Pacific Rise near 12°50′ N) led to the discovery of intense hydrothermal activity.
Abstract: A submersible study of a fast spreading (12 cm yr-1) Mid-Ocean ridge segment (East Pacific Rise near 12°50′ N) led to the discovery of intense hydrothermal activity. Twenty four sites with active vents and sixty inactive hydrothermal deposits were found within a narrow graben averaging about 300 m in width along a 20 km long segment of the ridge crest. The graben is floored with fresh basaltic sheet flows including collapsed pits or lava lake structures. From both deep towed camera stations and manned submersible observations, it is estimated that the average spacing between the ridge axis hydrothermal deposits averaging in size 10–50 m in diameter lies between 100 to 200 m.
104 citations
TL;DR: In this article, a new family of nitrided glasses has been discovered, which are prepared by reaction between ammonia and alkaline polyphosphates (MIPO3)n(MILi, Na, K) at 700°C and characterized as oxynitrides.
Abstract: A new family of nitrided glasses has been discovered. Nitrogen-containing phosphate glasses are prepared by reaction between ammonia and alkaline polyphosphates (MIPO3)n(MILi, Na, K) at 700°C and characterized as oxynitrides. High nitrogen contents are obtained. With MNa, for example, the vitreous field appears in the range NaPO3NaPO2N0.67 corresponding to a ratio N/O+N ⩽ 0.25. The existence of KPO3−3xN2x glasses exemplifies the role of nitrogen in the glass structure, which is built up on P(O,N)4 tetrahedra. At 700°C, the reaction between NH3 and P4O10 leads to glassy phases belonging to the HPON system.
81 citations
TL;DR: In this article, the authors found that the membrane potential in most Rana temporaria eggs did not change in any consistent pattern during 45 min after fertilization; in some cases, a slow hyperpolarization began 5 to 15 min after insemination and continued for 10-15 min These eggs then slowly depolarized, reaching a stable value of −10 to +10 mV.
80 citations
01 Jan 1983
TL;DR: In this article, the conditions générales d'utilisation (http://www.numdam.org/conditions) of the agreement with the séminaire de probabilités (Strasbourg) are described.
Abstract: © Springer-Verlag, Berlin Heidelberg New York, 1983, tous droits réservés. L’accès aux archives du séminaire de probabilités (Strasbourg) (http://portail. mathdoc.fr/SemProba/) implique l’accord avec les conditions générales d’utilisation (http://www.numdam.org/conditions). Toute utilisation commerciale ou impression systématique est constitutive d’une infraction pénale. Toute copie ou impression de ce fichier doit contenir la présente mention de copyright.
76 citations
TL;DR: Results of cross-fertilization experiments between Notophthalmus sperm and Rana eggs indicate that the voltage dependence of fertilization depends on the species of sperm.
74 citations
TL;DR: Photoperiod is confirmed as the major environmental determinant of reproduction in rainbow trout and a similar sequence of neuroendocrine changes was observed in both the first- and second-time spawning fish, thus indicating that similar pituitary-ovarian control mechanisms are in operation in all maturing fish irrespective of age.
TL;DR: In this article, a Fourier analysis of X-ray scattering by glasses in the system ZrF4-BaF2 is presented, where the first peak in the radial distribution functions occurs in the range 0.209 to 0.211 nm; the average coordination numbers estimated for the zirconium atom are in the ranges 7.08 to 8.35, depending on the chemical composition.
Abstract: A Fourier analysis of X-ray scattering by glasses in the system ZrF4-BaF2 is presented. The first peak in the radial distribution functions occurs in the range 0.209 to 0.211 nm; the average coordination numbers estimated for the zirconium atom are in the range 7.08 to 8.35, depending on the chemical composition. The second peak has been broken down into two components attributed to two kinds of Ba-F distances, 0.261 to 0.266 and 0.307 to 0.319 nm, with a corresponding coordination number of barium with respect to fluorine atoms ranging from 8.70 to 10.68. Interpretation of the cation-cation region is suggested; the average angle values of the Zr-F-Zr bridge bond, varying from 150° to 160° prevent two neighboring zirconium atoms from being bonded through two fluorine atoms. Comparative discussions with crystalline structures of fluorozirconates are presented.
TL;DR: Zusammenfassung photolysis of [CpFe(CO) 3 ] + PF 6 − in CH 3 CN in the presence of 2-, 4-, or 6-electorn ligands gives [cpFeL n (NCCH 3 ) 3− n ] +PF 6 − (n = 1: L = CO, PPh 3, cyclohexene, dimethylthiophene; n = 2: L 2 = dppe or n = 3: L 3 = cyclooctatetraene, or three phospholes),
TL;DR: Martin et al. as discussed by the authors showed that the first and second generations of grey gneisses are 2.86 -+ 0.09 and 2.62 ± 0.07 Ga, respectively.
TL;DR: Glycine betaine and stachydrin which exhibited the most pronounced anti-stress effect were utilized by the bacteria as substrates in the absence of any conventional carbon source.
TL;DR: In this article, conditions of tightness for sequences of processes are studied, which are mostly based on the use of dominating increasing processes. But they are not applicable to processes that are not quasi-left-continuous.
TL;DR: It is proposed that presynaptic modulation of acetyl-choline release occurs at the cercal-afferent giant-interneurone synapses at the picrotoxin and chloride-deficient salines abolished the inhibitory phenomenon.
TL;DR: In unfertilized frog eggs, the plasma membrane displays an animal vegetal polarity characterized by the presence of short microvilli in the vegetal hemisphere and long microVilli or ridge‐like protrusions in the animal hemisphere.
Abstract: In unfertilized frog eggs, the plasma membrane displays an animal vegetal polarity characterized by the presence of short microvilli in the vegetal hemisphere and long microvilli or ridge-like protrusions in the animal hemisphere. The densities of microvilli are similar in the two hemispheres.
The fertilizing sperm always fuses with the animal hemisphere of the egg and induces a wave of exocytosis of cortical granules from its site of penetration. Similar spreading of the cortical reaction is seen on activation by pricking the egg cortex. The integration of the cortical granule membrane with the plasma membrane is rapidly followed by elongation of microvilli, which is progressively realized all over the egg surface from the site of sperm entry or the site of pricking. At this time, the length and shape of the microvilli in the animal and vegetal hemispheres are similar and their densities are the same as in unfertilized eggs.
A “smoothing” wave can be seen on the living egg, 40–60 seconds after pricking, starting around the site of pricking. This wave of microvillar elongation is accompanied by changes in intensity of diffracted light spots observed at the surface of the egg. This pattern might result from rapid and progressive thickening of the cortex that would drive pigment granules into the cytoplasm. The Brownian movement of these granules is thought to be responsible for the observed diffracted light spots.
Electrical stimulus or the ionophore A23187 induced activation reactions similar to those triggered by the sperm or by pricking, except that the cortical reaction began simultaneously in several distinct sites of the cortex.
TL;DR: The specific heat and magnetic properties of GaMo4X8 (X=S, Se, SeTe) between 14 and 290 K are reported in this paper, which indicates an electron-phonon contribution to the Stoner enhancement factor.
Abstract: The specific heat and magnetic properties of GaMo4X8 (X=S, Se, SeTe) between 14 and 290 K are reported Our measurements tend to demonstrate that these compounds have a very high density of states, leading to a Stoner magnetic instability of conduction electrons at low temperatures The linear temperature-dependent term in the specific heat is enhanced by electron-phonon coupling and spin fluctuation effects These compounds could indicate an electron-phonon contribution to the Stoner enhancement factor
TL;DR: In this article, the authors show that the technique is basically an improved Euler method for integrating differential equations, and that unstrained elements (parallelepipeds) should therefore be fitted together so that face centres of adjoining elements coincide; or where this is not possible, the interfacial distances should be minimized.
TL;DR: It is shown that under natural assumptions such systems of algebraic equations arising in the application of B-stable Runge-Kutta methods do not always have a solution.
Abstract: This paper deals with the systems of algebraic equations arising in the application ofB-stable Runge-Kutta methods. It is shown that under natural assumptions such systems do not always have a solution. In addition, general sufficient conditions are presented under which such systems do have unique solutions.
TL;DR: In this article, energy distribution curves of photoemitted electrons are obtained for SnSe thin polycrystalline films in the 10 to 40 eV energy range, and the method of preparation of the sample under ultrahigh vacuum conditions is described and the synthesis of the initial material.
Abstract: Energy distribution curves of photoemitted electrons are obtained for SnSe thin polycrystalline films in the 10 to 40 eV energy range. The method of preparation of the sample under ultrahigh vacuum conditions is described and the synthesis of the initial material. The quality of the sample is checked by Auger analysis which reveals a weak reactivity of the material. The EDC's show structures appearing at 0.9, 2.1 to 2.7, 3.9, 7.4 eV below the top of the valence band. Also the Sn 4d levels are investigated. The 4d(5/2) is found at 24.3 eV and the 4d(3/2) at 25.3 eV below the top of the valence band. Structures in the EDC's are compared with those of existing similar works and are interpreted by means of theoretical bands scheme.
Les courbes de distribution energetique des electrons photoemis ont ete obtenues pour des couches minces polycristallines de SnSe dans la region 10 a 40 eV. Nous decrivons la methode de preparation de l'echantillon sous ultra-vide et la synthese du materiau de depart. La qualite de l'echantillon est contrǒlee par analyse Auger qui revele une faible reactivite du materiau. Les EDC montrent des structures apparaissant a 0,9; 2,1 a 2,7; 3,9; 7,4 eV en dessous du haut de la bande de valence. Nous avons aussi etudie les niveaux 4d de l'etain. Nous avons trouve les 4d(5/2) a 24,3 eV et les 4d(3/2) a 25,3 eV en dessous du sommet de la bande de valence. Les structures dans les EDC sont comparees avec celles de travaux similaires existant et sont interpretees au moyen de schemas des bandes theoriques.
TL;DR: In this article, the reaction scheme of thermal decomposition for four zinc hydroxynitrates was investigated by means of differential scanning calorimetry, thermogravimetric, mass spectrometry, and radiocrystallography.
TL;DR: In this article, the density change versus the nitrogen content indicates a higher compaction resulting from stronger electrostatic forces between Si(O,N) 4 tetrahedra and cations.
Abstract: Glasses have been prepared in the MSiAlON systems (M = Mg, Ca, Ba, Mn, Nd). The determination of their fields in the M x O y SiO 2 AlN sections allows a comparison with the corresponding oxide glasses. The density change versus the nitrogen content indicates a higher compaction resulting from stronger electrostatic forces between Si(O,N) 4 tetrahedra and cations. The variation of the number of gram-anions per unit volume with the cationic radius is a first approach of the structure of these glasses. Increasing the nitrogen content makes significant variations in some properties such as hardness, viscosity and Young's modulus.
TL;DR: A destabilization effect of oxalates on the membranes of parenchymatous cells of Beta vulgaris roots was demonstrated by measuring the efflux of betacyanins at 45°C, and it is suggested that such an interaction could play a role in the adaptative responses of Chenopodiaceae to saline conditions.
TL;DR: Comparative analyses on various batches of P. maritima gave further evidence for an adaptive function of sorbitol in salt resistance, which was partly related to some kind of stress response after transfer from field conditions to a Hoagland half strength medium.
TL;DR: A joint magnetic and mica fabric study has been carried out on rocks from recognized shear zones in Galicia (Spain) as discussed by the authors, where the main aims of the study were to determine strain gradients in a foliated material without any significant strain markers and to obtain a quantitative relationship between the magnetic susceptibility anisotropy ellipsoid and the mica fabrics axes.