Showing papers by "University of Lausanne published in 1971"
TL;DR: In this article, a method is described for direct measurement of the changes on alloying of the number of 3d electrons on transition metal atoms and of 3p electrons on Al atoms.
60 citations
TL;DR: The Juniper et al. finding that removing the cap prevented the perception of the gravitational stimulus although the root continued to elongate suggested that the root cap might be the site of geoperception and the source of growth regulating compounds.
Abstract: THE clear boundary1 between the cap and root proper in maize, enable assays such as those of Juniper et al.2 to be made. They found that removing the cap (decapping) prevented the perception of the gravitational stimulus although the root continued to elongate3; geosensitivity is regained when the cap is regenerated by the cap meristem. This suggested that the root cap might be the site of geoperception4–6 and the source of growth regulating compounds7.
57 citations
TL;DR: In this article, an oxepin synthesis from furanes and acetylenic dienophiles via Diels-Alder reaction (4a), photochemical oxanorbornadiene-oxaquadricyclane transformation (4b), and thermal 3σ 3π opening of the highly strained oxaquadiene 5a was described.
Abstract: Exemplifying with the 4.5-dicarbomethoxy oxepin 6a the authors describe an oxepin synthesis from furanes and acetylenic dienophiles via Diels-Alder reaction (4a), photochemical oxanorbornadiene-oxaquadricyclane transformation (4a 5a), and thermal 3σ 3π opening of the highly strained oxaquadricyclane 5a. With dimethylacetylenedicarboxylate, methylpropiolate, maleic anhydride, and di-methoxycarbonyl-oxanorbornadiene (4a) 5a yields the 1:1 adducts 19a, 19b, 22, 23 and 26 (unstable) by strictly stereospecific addition to the α-positions of the oxygen bridge. With the same dienophiles the oxepin 6a reacts only through its valence-tautomeric benzene-oxide form 7a giving stereospecifically 27, 29, 30 and 31. No definite conclusions are drawn with regard to the mechanistic implications of the photostep 4a 5a, the thermal 3σ 3π-transformation 5a 6a/7a, and the bishomofurane cycloaddition reactions. Scope and limitations of this oxepin synthesis are briefly discussed.
53 citations
TL;DR: Electrophoresis of RNA showed that the increase of specific radioactivity was essentially confined to heavy RNA, and the effect of ACh was not hindered when the generation of the action potential was prevented by tetrodotoxin.
51 citations
TL;DR: The efficiency of small enzyme-labeled tracers for the demonstration of intracellular antigen was investigated in tissues fixed with picric acid-formaldehyde and the influence of fixation on the immunological activity was tested in vitro by radial immunodiffusion.
Abstract: The efficiency of small enzyme-labeled tracers for the demonstration of intracellular antigen was investigated in tissues fixed with picric acid-formaldehyde. The influence of fixation on the immunological activity was tested in vitro by radial immunodiffusion. The experimental model consisted of newborn pig jejunum after absorption of ferritin from the intestinal lumen. Ferritin was located after 1 hr in vacuoles scattered in the cytoplasm of the absorptive cells and represented an easily recognizable intracellular antigen. After immunohistochemical treatments with antiferritin preparations, the distribution of labeling enzyme reaction product was examined by morphometry. The ratio of the labeled volume to the total volume of vacuoles containing ferritin indicated the degree of specific labeling of the antigen. In both direct and indirect methods, the degree of labeling was low when enzyme-labeled immunoglobulin G was the tracer. With antigen binding fragments (Fab), the labeling was significantly increased. In the indirect method, the degree of labeling was influenced by the first-step reagents. Onlywhen the serum titer was optimum was a high degree of labeling obtained. With antigen binding fragments or papain-digested serum the effect of the titer was negligible and maximum labeling was achieved. In both methods, with peroxidase as the labeling enzyme, a diffuse nonspecific deposition of reaction product was observed. This could be avoided by using cytochrome c instead.
50 citations
TL;DR: A modified Einstein-de Hass method has been developed sufficiently sensitive to measure the gyromagnetic ratio g' in paramagnetic transition metals as discussed by the authors, showing a large orbital magnetism in V, Cr, Nb and Ta.
Abstract: A modified Einstein-de Hass method has been developed sufficiently sensitive to measure the gyromagnetic ratio g' in paramagnetic transition metals. For the metals investigated the experimental values are Vanadium g' = 1.18 ± 0.10 Chromium g' = 1.21 ± 0.07 Niobium g' = 1.05 ± 0.07 Tantalum g' = 1.02 ± 0.07 Palladium g' = 1.77 ± 0.10 Platinum g' = 1.62 ± 0.08 From these values the contributions from orbital and spin effects can be resolved, showing a large orbital magnetism in V, Cr, Nb and Ta.
41 citations
TL;DR: It is concluded that the secretory granules of parafollicular cells contain calcitonin; the mechanism of synthesis of this peptide is not clearly understood.
Abstract: Parafollicular cells in mammalian thyroid glands are thought to be responsible for the secretion of calcitonin. In this study, calcitonin was localized in pig thyroid gland by an indirect immunocytochemical technique using rabbit antiserum directed against synthetic porcine calcitonin for the first step, and sheep Fab fragments prepared against rabbit Fab and coupled to cytochrome c for the second step. The antigenic determinants of calcitonin were present only in the parafollicular cells, whose secretory granules were heavily labeled. Labeling of the cytoplasmic matrix is thought to indicate a possible leakage of the polypeptide from the granules. A striking observation was the complete absence of labeling in the cisternae of the rough-surfaced endoplasmic reticulum and of the Golgi apparatus. It is concluded that the secretory granules of parafollicular cells contain calcitonin; the mechanism of synthesis of this peptide is not clearly understood.
29 citations
TL;DR: In the gas phase, 2-Quinolylnitrene (II) rearranges to 1-isoquinoxalylnitrene (XVI) and 4-quinazoline (XIV) to give identical products, 1-cyanobenzimidazole (XVIII) and N-cyano-anthranilonitrile (XX), formed by ring contraction and ring opening as mentioned in this paper.
27 citations
TL;DR: In this article, the (S)-configuration at the single asymmetric carbon atom gave strong positive Cotton effects near 220 nm for α-cyclohexyl-α-amino acids and esters.
Abstract: CD. curves have been recorded for α-aryl-α-amino acids, esters and amides related to α-phenylglycine, α-phenyl-alanine and their N-dimethyl derivatives, and for the corresponding α-cyclohexyl-α-amino acids and esters. Compounds with the (S)-configuration at the single asymmetric carbon atom give strong positive Cotton effects near 220 nm. The conformations of the acids are discussed and compared with those of other α-amino acids.
23 citations
TL;DR: In this paper, the ABA effects on the basipetal transport of IAA-2-14C, using sections of epicotyls prepared from etiolated seedlings, were analyzed.
Abstract: Several experiments have been performed to analyse the ABA effects on the basipetal transport of IAA-2-14C, using sections of epicotyls prepared from etiolated Lens seedlings. The sections were incubated in an ABA solution or ABA was applied in the donor blocks containing IAA. For each type of assay, the uptake (analyses of the donor blocks) and the movement of IAA-C14 (analyses of the receiver blocks) were inhibited by ABA. The distribution of continuous decrease of the radioactivity, along the sections' axis, showed a 14C level from the apical towards the basal segments. ABA caused a decrease in the 14C concentration for the total sections, but a relative increase for the basal segment. When ABA was applied simultaneously with IAA in the donor blocks, the transport velocity of IAA, through the sections, was not changed significantly, while an ABA pretreatment caused a significant decrease.
17 citations
TL;DR: Results are consistent with the assumption that in a modified low-sodium Tyrode procaine reduces a slow inward current of calcium ions, causing an electromechanical decoupling, and the negative inotropic effect of procaine seems to be fully explained by the shortening of the action potential.
Abstract: 1
Both membrane potential and contraction were recorded in muscle trabeculae of sheep hearts Addition of 40 mg-% of procaine to the Tyrode solution decreased the rate of rise of the action potential, reduced its duration and decreased the strength of contraction
2
Trabeculae depolarized uniformly by square current pulses across a double sucrose-gap in Tyrode solution gave a mechanical response which was not affected by the presence of procaine (60 to 100 mg-%) With a modified low-sodium Tyrode (5 mM Na/l) however, the mechanical response to the depolarizing current decreased until it reached zero, on addition of procaine to the solution
3
All these effects of procaine were completely reversible up to concentrations of 100 mg-% applied for 1 hour
4
Increasing the calcium concentration to 9 mM/l in the presence of procaine restored the contraction in a low-sodium solution
In the absence of procaine, the same increase of the calcium concentration had a large positive inotropic effect in the Tyrode solution but not in the low-sodium solution
5
The addition of 2 mg-% of TTX to the Tyrode solution in presence of 100 mg-% of procaine did not alter the mechanical response
6
These results are consistent with the assumption that in a modified low-sodium Tyrode procaine reduces a slow inward current of calcium ions, causing an electromechanical decoupling
TL;DR: The observed decrease in plasma volume was large enough to explain the drinking response to renin and angiotensin, and may thus induce or aggravate hypovolaemia rather than signalling its occurrence to hypothalamic receptors.
Abstract: 1. Intravenous injection of five Goldblatt units (Gbl.U) of renin, or intravenous infusion of 2.5 mug of angiotensin into nephrectomized rats decreased plasma volume by 22 +/- 2% (calculated from the increase of the haematocrit) or by 14 +/- 2% (calculated from the increase in protein concentration) within 2 minutes. Fifteen minutes and 60 min after injection or infusion, the plasma volume (calculated from both parameters) was still 10% lower than initially.2. The initial discrepancy between haematocrit values and plasma protein concentration was neither due to mobilization of red blood cells (r.b.c.) from the spleen, nor to an increase in r.b.c. volume.3. The observed decrease in plasma volume was large enough to explain the drinking response to renin and angiotensin. Renin may thus induce or aggravate hypovolaemia rather than signalling its occurrence to hypothalamic receptors.
TL;DR: The experimental study at 25°C of the system KClRbClCsClH2O has shown the existence of a new type of quaternary system with formation of mixed crystals as discussed by the authors.
Abstract: The experimental study at 25°C of the system KClRbClCsClH2O has shown the existence of a new type of quaternary system with formation of mixed crystals. — The solubility diagram is characterized by the presence of one univariant line and one binary miscibility gap. Two types of solid solutions are present: (K, Rb, Cs) Cl and (K, Rb, Cs) Cl; the incorporation in the latter is small.
TL;DR: The renal excretion of uric acid was studied in unanesthetized rats by clearance methods at different levels of plasma concentrations, of urine flow and of urinary pH, and tubular secretion ofUric acid in the rat was suggested by the persistence of urinary excretion at very low plasma levels.
Abstract: L'excretion renale de l'acide urique a ete etudiee chez le rat eveille par des mesures de clearance, a differents taux plasmatiques d'acide urique et dans differentes conditions de debit et de pH urinaires.
TL;DR: In this paper, the chemistry of diamagnetic nitrilotriacetate complexes of scandium, yttrium, lanthanum and lutecium in aqueous solution is studied.
Abstract: Proton nuclear magnetic resonance has been used to study the chemistry of the diamagnetic nitrilotriacetate complexes of scandium, yttrium, lanthanum and lutecium in aqueous solution Complexes with ligand-to-metal ratios of 1 and 2 are present depending of the solution conditions The ligand exchanges by spontaneous and by acid catalysed dissociation of the metal-bis-nitrilotriacetate, and also by a bimolecular process involving the free ligand and the complex The ligand exchange rate constants decrease with the ionic radii:lanthanum > yttrium > lutecium > scandium
TL;DR: The product of photolysis of di-p-tolyamine in petroleum ether is 3,6-dimethyl carbazole as discussed by the authors, which is also the primary product of gas-phase thermolysis of tetra-ptolylhydrazine at 850-1000°/0.01-0.05 Torr.
Abstract: The product of photolysis of di-p-tolyamine in petroleum ether is 3,6-dimethylcarbazole. The primary product of gas-phase thermolysis of di-p-tolylamine at 850–1000°/0.01–0.05 Torr is also 3,6-dimethylcarbazole. In the higher temperature range monomethylcarbazole and carbazole are also formed. Thermolysis of tetra-p-tolylhydrazine at 800–1000° gives only di-p-tolylamine, the latter decomposing further in the higher temperature range. It is concluded that carbazole formation involves in both cases an electrocyclization of the ortho-positions, and not a rearrangement, and that diphenylaminyl is not an intermediate.
TL;DR: In this article, the acid catalysed hydrolysis of three mono-diazomethanes (p)-nitrophenyl-diaomethane (I), p-chlorophenyl-dimethylamine (II), phenyl-Diazomethrane (III), absence of exchange H-D, solvent isotope effects about 2,6, and general acid catalysis prove that proton transfer is rate determining (A-SE2 mechanism).
Abstract: In the acid catalysed hydrolysis of three monoaryl-diazomethanes (p)-nitrophenyl-diazomethane (I), p-chlorophenyl-diazomethane (II), phenyl-diazomethane (III), absence of exchange H-D, solvent isotope effects about 2,6, and general acid catalysis prove that proton transfer is rate determining (A-SE2 mechanism). Like other A-SE2 reactions, the hydrolysis of I is shown to obey the Bronsted catalysis law with a variety of carboxylic acids; for eight of these acids, αB was found to be 0,69 ± 0,06.
TL;DR: In this paper, the epimeric N-oxide structures of (−)-laurepukine and 6-epi-laure pukine were shown to possess epimericity.
Abstract: The alkaloid (−)-laurepukine is shown to possess one of the epimeric N-oxide structures 4 or 5. Oxidation of (−)-pukateine (3) by hydrogen peroxide gives (−)-laurepukine and, as a second product, 6-epi-laurepukine.
TL;DR: In this paper, two sets of results concerning meromorphic approximations of scattering amplitudes are presented, one characterizes the distribution of the zeros and the second deals with the implications of the polynomial character of the residues on the aymptotic behavior.
TL;DR: Trishexafluoro-2propoxides of yttrium, lanthanum, neodymium and erbium have been prepared by the ammonia method, directly from the hydrated rare earth chlorides, dehydrated in situ by trimethyl orthoformate as discussed by the authors.
Abstract: Tris-hexafluoro-2-propoxides of yttrium, lanthanum, neodymium and erbium have been prepared, by the ammonia method, directly from the hydrated rare earth chlorides, dehydrated in situ by trimethyl orthoformate. The compounds are not volatile.
TL;DR: The relative stability constants of the adducts of MCl5 (M Nb, Ta) with acetonitrile, halogenoacetonitriles, pivalonitrile and acrylonitrile were determined in dilute solutions by NMR methods as mentioned in this paper.
Abstract: The relative stability constants of the adducts of MCl5 (M Nb, Ta) with acetonitrile, halogenoacetonitriles, pivalonitrile, acrylonitrile and benzonitriles are determined in dilute solutions by NMR. methods. The stability of the adducts is controlled by inductive factors. Chemical shifts and analysis of the new compounds are reported.
TL;DR: Probenecid (200 mg/kg b.c., i.w.) had a pronounced uricosuric effect at the physiological low plasma level of uric acid, and inhibiteurs de la sécrétion, diminuent d'autant plus fortement l'excrétions rénale d'acide urique, que le taux plasmatique d'acid urique est plus élevé.
Abstract: L'excretion renale de l'acide urique a ete etudiee chez le rat nonanesthesie par des mesures de clearances, avant et apres l'administration d'agents inhibiteurs des transports d'acide urique.
TL;DR: In this paper, NMR methods for the determination of stability constants of niobium and tantalum halides have been discussed in view of a systematic study of the Lewis acidity of the halides.
Abstract: In view of a systematic study of the Lewis acidity of niobium (V) and tantalum (V) halides, NMR. methods for the determination of stability constants are discussed. In the case of rapid exchange chemical shifts are used to determine the relative amounts of adduct(s) and free base(s) in equilibrium. In the case of slow exchange the relative concentrations of the species are given by the peak areas.
TL;DR: The speed at which magnetic flux propagates in superconducting tin and indium disks suddenly subjected to an axial magnetic field lower than the critical has been measured by direct observation as discussed by the authors.
Abstract: The speed at which magnetic flux propagates in superconducting tin and indium disks suddenly subjected to an axial magnetic field lower than the critical has been measured by direct observation. The results are discussed in terms of an energybalance argument based on eddy-current damping and assuming isothermal penetration.
TL;DR: In this article, the syn-coplanar cleavage of hydrogen halide was favored in the dehydrohalogenation of trans-1,2-dichlorocyclodecane and trans- 1, 2-dibromocyclidecane, and the anti elimination was most favored with acyclic compds.
Abstract: syn-Coplanar cleavage of hydrogen halide, esp. the syn -> trans process, was favored in the dehydrohalogenation of trans-1,2-dichlorocyclodecane and trans-1,2-dibromocyclodecane, and the anti elimination, which was most favored with acyclic compds., was retarded. The transition state for syn elimination was thought to be stabilized by redn. in transannular repulsive forces. The dehydrohalogenation rate depended only slightly on the solvent. [on SciFinder (R)]
TL;DR: In this article, the magnetic moment of the Δ-hyperon was measured by observing the precession of the polarization vector of Δ-particles in a transverse pulsed magnetic field of 20 T (= 200 kG).
Abstract: The magnetic moment of the Δ-hyperon has been measured by observing the precession of the polarization vector of Δ-particles in a transverse pulsed magnetic field of 20 T (= 200 kG). The hyperons were produced in a polyethylene target by the reaction π−+p→+Δ+K0 at a pion momentum of 1.05 GeV/c; their decays were detected in stacks of nuclear emulsion at a distance of 11 em from the centre of the target. The angular distribution of the decay products in the rest frame of the Δ was used to determine the direction of the polarization at the time of the decay, and hence the magnetic moment. About 1300 Δ decays have been analysed, giving the result\(\mu _\Lambda = - 0.66\mu _{\mathcal{N}}\) (nuclear magnctons) with a statistical uncertainty of\( \pm 0.06\mu _{\mathcal{N}}\). The systematic error is less then\( \pm 0.03\mu _{\mathcal{N}}\), so that the total (68% confidence level) error is\( \pm 0.07\mu _{\mathcal{N}}\).
01 Jan 1971
TL;DR: In this paper, the dynamics of the destruction of type I superconductivity in a wire by an overcritical current are studied, where a normal region grows from the surface surrounding a superconducting cylindrical core which contracts until its radius reaches the radius of the intermediate state core according to London's picture.
Abstract: The dynamics of the destruction of type I superconductivity in a wire by an overcritical current are studied. In a first time interval a normal region grows from the surface surrounding a superconducting cylindrical core which contracts until its radius reaches the radius of the intermediate state core according to London's picture of the static state. In a second step the intermediate state is built up between the normal shell and the superconducting core, which finally disappears. The onset of the intermediate state is a consequence of an instability of the interphase boundary.