showing 36 of ~574560 from 574555 documents
Mass spectra of chlorinated aromatics formed in pulp bleaching: I—chlorinated catechols
1983
The fragmentation of chlorinated guaiacols (2-methoxyphenols) on electron impact has been studied. The most common fragmentation processes are interpreted and in some cases the small differences between spectra of positional isomers are explained. In addition to the well-known alkyl-oxygen fission (loss of methyl radical), metastable ion studies and deuterium labelling have indicated several new fragmentation pathways. The most characteristic are the formation of [MCH3HCl]+ and [MCH3Cl]+· ions. In general, however, the spectra of positional isomers are shown to be very similar.
Biological activation of 1,3-butadiene to vinyl oxirane by rat liver microsomes and expiration of the reactive metabolite by exposed rats.
1983
When 1,3-butadiene is incubated with rat liver microsomes and NADPH both enantiomers of vinyl oxirane are formed, the amount of epoxide being dependent on incubation time, microsomal protein, and substrate concentration. Inhibition by SKF 525 A or dithiocarb as well as induction by pretreatment with phenobarbital or 20-methylcholanthrene suggest participation of cytochrome P-450 in this reaction. The amount of epoxide is enhanced by addition of 1,1,1-trichloropropene oxide and reduced by glutathione, especially in the presence of hepatic cytosol. When rats are exposed to 1,3-butadiene in a closed chamber (conditions of maximal metabolism) vinyl oxirane is exhaled and can be quantitatively d…
Monte-Carlo calculations of keV electron and positron slowing down in solids
1983
A Monte-Carlo simulation technique based on the screened Rutherford differential cross section for the elastic scattering and Gryzinski's semiempirical expression for the inelastic core and valence electron excitation is used to describe electrons and positrons slowing down in solids. The theoretical results are compared with the experimental backscattering, absorption and transmission results for aluminum, silicon, copper, and gold thin film and semi-infinite targets and good agreement is observed. The simulated stopping profiles are fitted with a simple analytic expression. The profiles are Laplace-transformed to give a useful data base for analyzing phenomena associated with slow positro…
Optimality conditions for nondifferentiable convex semi-infinite programming
1983
This paper gives characterizations of optimal solutions to the nondifferentiable convex semi-infinite programming problem, which involve the notion of Lagrangian saddlepoint. With the aim of giving the necessary conditions for optimality, local and global constraint qualifications are established. These constraint qualifications are based on the property of Farkas-Minkowski, which plays an important role in relation to certain systems obtained by linearizing the feasible set. It is proved that Slater's qualification implies those qualifications.
Effect of a filler on the dielectric properties of an epoxy resin
1983
The effect of aluminum hydroxide upon the dielectric properties of an epoxy resin has been studied in a wide frequency and temperature range. An interfacial polarization effect, known as the Maxwell–Wagner–Sillars polarization is evidenced for the filled resin, which shows a higher permittivity, a higher dielectric loss, and a β transition with a larger relaxation time. The glass transition temperature is, on the contrary, mostly unaffected by the presence of the filler.
THERMOTROPIC HOMOPOLYESTERS. IV. STUDY OF FIBER FORMATION.
1983
We report a melt spinning and viscosity study of two semiflexible homopolyesters containing both rigid and flexible segments in the repeating unit. Single filaments of the polyesters formed from 4,4′-diacetoxybiphenyl and azelaic acid (PB7) and sebacic acid (PB8), and from 4′-hydroxyphenyl-4-hydroxycinnamate and azelaic acid (C7), were spun at temperatures between 205 and 255°C. The temperature dependence of the Newtonian melt viscosity of PB7 and C7 was investigated, and a range of molecular weights was studied for PB7. The spinning parameters, fiber characteristics, and viscosity-temperature behavior are related to the type of mesophase formed. The mechanical properties of fibers spun fro…
Book Review: Comprehensive Organometallic Chemistry. The Synthesis, Reactions and Structures of Organometallic Compounds. Nine volumes. Editors G. Wi…
1983
Estimacion de modelos de eleccion cualitativa
1983
International audience; En su expresión más simple, los modelos de respuesta cualitativa asocian la realización de una elección binaria o dicotómica a un cierto número de características exógenas juzgadas «a priori» pertinentes. El tratamiento de estos modelos, que se generaliza fácilmente para tener en cuenta una realidad más compleja (elección múltiple), obstaculiza las hipótesis usuales de la estimación econométrica. debido a que la variable explicada se identifica con una probabilidad. Para paliar estos inconvenientes lo más usual es sustituir la especificación lineal clásica por la función de distribución logística estandarizada, que se estima por el método de máxima verosimilitud o po…
Graphical representation of polynuclear acid-base and complex equilibria.
1983
Abstract A calculation procedure for diagrams of log CM = ƒ(pL) at various values of the ratio of analytical concentrations, CL/CM, in polynuclear binary systems is described. The diagrams are useful in the resolution of analytical problems of practical interest involving acid-base equilibria (such as the preparation of buffer solutions) and complex equilibria. The presence of a solid phase is also considered.
One-nucleon transfer reactions induced by 32S on 34S AT Einc = 90.0 and 97.09 MeV
1983
Abstract The one-proton and one-neutron transfer reactions in the interaction of 34 S with incident 32 S were studied in the 0–3.5 MeV excitation energy range of the exit nuclei. The experimental set-up (kinematic identification technique, implanted targets, etc.) has allowed an angular resolution of 0.2°, a mass resolution of 1.5% and a Q -value resolution of 0.35 MeV. Comparison with DWBA computations using an analytical approximation for the radial integral, with insertion of suitable recoil corrections, demonstrates the absorptive direct mechanisms of the reactions, even when double excitation of residual nuclei is present. The extracted values for the products of spectroscopic factors …
Susceptibility of mouse skeletal muscles to exercise injuries.
1983
The susceptibility to exercise-induced myopathy was studied by histological and biochemical methods in various skeletal muscles of mice 3-4 days after a single bout of prolonged running. The degree of exercise injuries varied greatly in different muscles. Soleus and the red deep parts of quadriceps femoris were the most severely affected muscles. Extensive or scattered necrosis of muscle fibers was associated with focal inflammation and a five- to nine-fold increase in the activity of beta-glucuronidase in these muscles. Slight necrotic changes and a two- to three-fold increase in the activity of beta-glucuronidase were observed in tibialis anterior, plantaris, and the red deep parts of gas…
Half-life ofTi44
1983
The half-life of $^{44}\mathrm{Ti}$ has been measured to be ${T}_{\frac{1}{2}}=54.2\ifmmode\pm\else\textpm\fi{}2.1$ yr, somewhat higher than previously published values of 46.4\ifmmode\pm\else\textpm\fi{}1.7 and 48.2\ifmmode\pm\else\textpm\fi{}0.9 yr. The present value was obtained from the specific activity and the radioisotope concentration of several Ti${\mathrm{O}}_{2}$ samples, each spiked with a $^{44}\mathrm{Ti}$ activity of about 1.2 \ensuremath{\mu}Ci. The specific activity was measured via the 1157 keV $\ensuremath{\gamma}$ line from the decay of the $^{44}\mathrm{Sc}$ daughter. $^{44}\mathrm{Ti}$/Ti concentrations were measured with the Argonne FN tandem accelerator in conjunctio…
La première campagne (1982-1983) de formations alternées au bénéfice des jeunes de 16 à 18 ans : bilan, enseignements, perspectives
1983
International audience
VAPOR-LIQUID EQUILIBRIUM CALCULATIONS USING THE TOPOLOGICAL TREATMENT OF MIXTURES.
1983
The Topological Treatment of mixtures is applied to several kinds of binary mixtures to obtain VLE diagrams. The excess Gibbs free energy, gE, is calculated as the product of a topological vector and an information vector. The pure compound topological description were obtained following the DARC system rules. A weighting function was introduced to obtain the topological description of a mixture. The information vector is calculated from experimental data. It is shown that for binary mixtures alcohol-alkane, the components of this vector varies linearly with the average number of carbon atoms of chemical compounds. This relationship allows prediction of the VLE diagram for any other system …
Psychotropic drug competition for [3H]imipramine binding further indicates the presence of only one high-affinity drug binding site on human α1-acid …
1983
Correlation between different degree and duration of metabolic control and thyroid hormone levels in type 1 and type 2 diabetics.
1983
Thyroxine (T4), triiodothyronine (T3), reverse T3 (rT3) and HbA1c were assayed in 21 insulin-dependent (type 1) diabetics and in 45 non-insulin-dependent (type 2) diabetics with normal thyroid function and different levels of control, and were compared to values found in apparently healthy controls. rT3 and rT3/T3 ratio were significantly increased both in type 1 and type 2 diabetics. T3 and T4 were significantly lower in type 2 diabetics than in the controls. Significant positive correlations of HbA1c to rT3 (r = 0.63) and to rT3/T3 ratio (r = 0.53) were found in type 1, and in type 2 diabetics (HbA1c, rT3-r = 0.50), (HbA1c, rT3/T3-r = 0.37). There was no correlation between glycemia (BG),…
Biomolecular-solvent stereodynamic coupling probed by deuteration.
1983
Thermodynamic interpretation of experiments with isotopically perturbed solvent supports the view that solvent stereodynamics is directly relevant to thermodynamic stability of biomolecules. According with the current understanding of the structure of the aqueous solvent, in any stereodynamic configuration of the latter, connectivity pathways are identifiable for their topologic and order properties. Perturbing the solvent by isotopic substitution or, e.g., by addition of co-solvents, can therefore be viewed as reinforcing or otherwise perturbing these topologic structures. This microscopic model readily visualizes thermodynamic interpretation. In conclusion, the topologic stereodynamic str…
Effect of dietary antioxidants on benzo[a]pyrene metabolism in rat liver microsomes
1983
Feeding of rats with 1% ethoxyquin (EQ) and butylated hydroxytoluene (BHT) but not butylated hydroxyanisole (BHA) increases the formation rate of benzo[a]pyrene (BP)-4,5-dihydrodiol from BP in hepatic microsomes. The production of other BP-dihydrodiols and of BP phenols is decreased after treatment with EQ, BHT and BHA. EQ and BHT are more effective than BHA in inducing epoxide hydrolase (EH) activity towards styrene oxide as the substrate.
In-Beam Study of213Rn,215Ra and217Ra: Strongly Enhanced E3 Transitions in Odd-A N= 127 Isotones
1983
With the aim of searching for high-spin configurations involving the high-j neutron orbitals, excited states in 213Rn, 215Ra and 217Ra were populated in the bombardment of 208Pb with 13C ions. Gamma-ray singles, excitation functions and angular distributions, pulsed-beam-γ timing and γ-γ(t) coincidences were measured. Six isomeric levels were observed in 213Rn, three in 215Ra while none in 217Ra. The lowest-lying 15/2- states in all odd-A N = 127 isotones are de-excited by E3 transitions with a strength of about 23 W.u, suggesting that they are all coupled to the octupole phonon. In 217Ra no evidence for collective behavior is found despite its closeness to the actinide region. The low-lyin…
About some psychological variables correlated with dogmatism
1983
The relationships between dogmatism and some perceptual-cognitive, personality, and attitudinal indices were investigated for 40 men and 40 women. Dogmatism scores correlated negatively with the scores in Witkin's Group Embedded Figures Test and on the Flexibility scale from Gough's California Psychological Inventory. Correlations were positive for a favorable attitude towards concepts like Discipline, Obedience, Social order, measured by the semantic differential. Some incongruities between obtained data and Rokeach's (1960) findings are pointed out.
Determination of nuclear spins and moments in a series of radium isotopes
1983
Abstract The first investigation of hyperfine structure in radium isotopes has enabled the determination of nuclear spins, magnetic dipole and electric quadrupole moments of the isotopes with mass numbers A = 211, 213, 221, 223, 225, 227 and 229. Isotope shifts in the mass range A = 208−232 have also been measured. These studies were carried out using the technique of on-line collinear fast beam laser spectroscopy.
Le système technologie, marché du travail et gestion de la main d'oeuvre : l'exemple de l'industrie électronique et électrique française au Brésil
1983
International audience
Quantum Motion of Chemisorbed Hydrogen on Ni Surfaces
1983
Quantum mechanical energy levels and wave functions have been calculated for the motion of chemisorbed hydrogen atoms on Ni surfaces. The results show considerable quantum effects for the adatom in both the ground and the excited states. The description of the adparticles as being delocalized along the surface offers a novel interpretation of several phenomena, in particular the vibrational excitations. Peer reviewed
Synthese von 2-Acyloxy- und 2-Alkyloxy-3-ketoglycalen und ihren Bromaddukten
1983
Die an den Hydroxygruppen acetyl-, pivaloyl- und methylgeschutzten 2-Hydroxy-3-ketoglycale 5a, 5b bzw. 11 werden durch Oxidation der entsprechenden 1-O-Acylglucopyranosen 3a, 3b bzw. 9 an der freien 3-Hydroxygruppe mit Dimethylsulfoxid/Acetanhydrid oder Chlorsulfonylisocyanat hergestellt und charakterisiert. Nur beim Acetylderivat 3a verlaufen die Oxidation und die Eliminierung des 1-Acetyloxysubstituenten in einem Schritt. Beim Pivaloylderivat 3b und beim Methylderivat 9 mus die Eliminierung aus der 3-Ulose 4 bzw. 10 mit Diazabicycloundecen (DBU) vervollstandigt werden. – Die geschutzten Hex-1-enopyran-3-ulosen 5a, 5b und 11 addieren Brom stereoselektiv unter Bildung der D-ribo-konfigurier…
Essai de modelisation des echanges en foret et role de la structure d'un couvert forestier sur l'evapotranspiration en particulier
1983
La foret et le bois; National audience
The new neutron-rich isotope183Lu
1983
The new neutron-rich isotope183Lu was produced in multinucleon transfer reactions by irradiatingnatW/Ta targets with 11.7 MeV/u136Xe ions, and identified by mass separation and decay spectroscopy. The measured half-life of183Lu is 58±4 s. The properties of the excited states of183Hf are discussed.
Epitope specificity and Ia restriction of T cell responses to insulin in a system of complementing Ir genes: analysis with primed lymph node T cells …
1983
The antibody response of (H-2b X H-2k)F1 mice to pig insulin (PI) has previously been shown to be under the control of H-2-linked, complementing Ir genes. In addition, this response was reported to depend on the genetic background of the parental strains (Keck, K., Eur. J. Immunol. 1977. 7: 811). Here it is demonstrated that the secondary in vitro response of proliferating T cells shows the same dependence on H-2-linked Ir genes yet an influence of the background genes could not be detected. The complementing genes were mapped to the Kb, I-Ab and Kk, I-Ak regions. For restimulation of F1 T cells by PI, the Ir genes of both parental chromosomes have to be expressed in the same antigen-presen…
Stimulation of PGE and TXB2 release from macrophages by C3b
1983
Elastic properties of CsCN
1983
The temperature dependence of the elastic constants of CsCN exhibiting the CsCl structure was measured with ultrasonic and neutron techniques. The room temperature values were found to bec11=18.8,c12=10.7 andc44=2.95 1010 dyn/cm2. The sound waves inT2g andEg symmetries exhibit anomalous temperature effects which are similar but definitively weaker than those in the NaCl type cyanides. In addition we measured the acoustic phonon dispersion along [100] and [110]. These results are compared with recent molecular dynamics calculations.
false
1983
The kinetics of the electrophilic bromination of 17 oligonuclear phenolic compounds with molecular bromine in acetic acid were studied at 22°C. Some of these compounds, consisting of up to 6 phenolic units, which are linked in ortho-position by methylene bridges, and having only one (or two) reactive ortho-position(s) at the end of the molecule, were synthesized for the first time. It could be shown, even for hexanuclear compounds, that the variation of substituents at one end of the molecule leads to a change in the reactivity at the other end, that means over a distance of 22 nonconjugated covalent links. So far, this can be explained only by a chain of intramolecular hydrogen bonds betwe…
Analysis of male recombination in third chromosomes of Drosophila melanogaster
1983
Data on male recombination in twenty third-chromosomal lines of Drosophila melanogaster are presented. Frequencies of female and male recombination have been calculated in seven intervals along the third chromosome. The influence on male recombination (M.R.) exercised by different factors such as population origin (cellar, vineyard), the presence of heterozygous inversions and recessive lethal chromosomes, is analyzed. The results obtained lead to the main conclusion that M.R. is not affected by the presence of heterozygous inversions which reduce female recombination in the same lines. In the light of this effect, the possible mechanism operating on male recombination is discussed. Lethal …
En Bourgogne, insertion des jeunes ayant un CAP ou un BEP
1983
Référence interne : 83026; A partir des résultats des deux enquêtes successives réalisées par le CEREQ, dans le cadre de l'observatoire national des entrées dans la vie active, l'auteur étudie les conditions d'insertion professionnelle de deux promotions de jeunes, sortant de formations techniques courtes (CAP et BEP) et son évolution en région Bourgogne. Une des finalités assignées à l'enseignement professionnel est de donner une formation qualifiante, de préparer les jeunes à une entrée directe dans la vie active. Que deviennent les élèves de l'enseignement technique court ? Dans quelles conditions ces jeunes s'insèrent-ils dans la vie active, à quatre ans de distance ? Comment a évolué l…
On Baer subspaces of finite projective spaces
1983
Estructura de la Exportacion y Distribucion de Beneficios. La Naranja en el Pais Valenciano (1920–1930)
1983
A diferencia de la tendencia hacia la autarquía del conjunto de la economía española durante el primer tercio del siglo xx, los decenios iniciales de la centuria suponen en el País Valenciano un período en el que se consolidan sus vinculaciones con el mercado exterior, como resultado del espectacular aumento de las exportaciones. De esta forma, mientras los años que siguen a la contienda europea constituyen para España la etapa de culminación del modelo de crecimiento basado en la sustitución forzosa de importaciones y en el fomento directo de la demanda industrial por parte del Estado, para el País Valenciano, el decenio posterior a la guerra y, en especial, los años de la Dictadura de Pri…