Showing papers by "Conservatoire national des arts et métiers published in 1988"
TL;DR: In this paper, the conditions of appearance of mechanical twinning and its role in texture development during uniaxial tension, biaaxial expansion and rolling of Ti and Zr alloys are studied.
Abstract: This paper presents an extensive study of the conditions of appearance of mechanical twinning and its role in the texture development during uniaxial tension, biaxial expansion and rolling of Ti and Zr alloys.
60 citations
TL;DR: Examination of the physiological activity of flavonoids in relation to their antiscorbutic properties shows that some of these compounds, the flavan-3=ols, have a particular nutritional impact and consequently should be distinguished from the rest of the flavonoid and polyphenolds.
Abstract: Examination of the physiological activity of flavonoids in relation to their antiscorbutic properties shows that some of these compounds, the flavan-3=ols, have a particular nutritional impact and consequently should be distinguished from the rest of the flavonoids and polyphenolds. Therefore, the use of the term ‘Vitamin P’ and ‘Bioflavonoids’ is also discussed.
38 citations
TL;DR: The frequency of anaemia was not correlated with the degree of malarial infection nor to the type of haemoglobin, and there was no difference between rural and urban groups, except for children 73–168 months old, in whom the prevalence was higher in the rural group.
35 citations
33 citations
TL;DR: In this article, the steric conditions associated to the various possibilities of covalent derivatization have been analyzed, leading to the definition of a functionalization space, compatible with the preservation of high conductivity and electrochemical reversibility in the resulting polymers.
Abstract: The mechanism of the electropolymerization of thiophene derivatives has been investigated by varying the electrosynthesis conditions and the monomer structure. The results of these analyses led to the definition of optimized electrosynthesis conditions allowing the control of the electrical and electrochemical properties of poly(thiophenes). On the basis of these results, the properties of these polymers have been modified by means of a new one-step electrosynthesis of conducting composite materials and by the direct electropolymerization of tailor-made functionalized monomers. For this purpose, the steric conditions associated to the various possibilities of covalent derivatization have been analyzed, leading to the definition of a “functionalization space”, compatible with the preservation of high conductivity and electrochemical reversibility in the resulting polymers. This concept has been applied to the synthesis of highly conducting chiral poly(thiophenes) on which an effect of enantioselective molecular recognition has been demonstrated for the first time.
14 citations
TL;DR: In this article, a new method for the preparation of pure enantiomers of α-amino acids is described, and the physical constants of natural and xenobiotic L-Zamino acid esters and D-Z amino acids are described.
13 citations
Journal Article•
TL;DR: Compared in small intestine and liver of male Wistar rats from 18 to 60 days of life, discontinuities in the developmental pattern of UDP-glucuronosyltransferase, and the ontogenesis of glutathione-S-transferase activities differed according to the substrate metabolized were observed.
Abstract: The postnatal development of NADPH-cytochrome c reductase, UDP-glucuronosyltransferase, selenium-dependent glutathione peroxidase, glutathione-S-transferase activities, total non-protein sulfhydryls, and cytochrome P-450 contents was compared in small intestine and liver of male Wistar rats from 18 to 60 days of life. In the intestine, main age-related changes affected conjugation enzymes which were increased rapidly by a factor of 4 during the weaning time and remained unchanged thereafter. Development in the rat was accompanied by changes in cytochrome P-450 content and NADPH-cytochrome c reductase activity only in the liver. In both organs, glutathione concentration and selenium-dependent glutathione peroxidase activity were not significantly modified between 18 and 60 days. In the liver, we observed discontinuities in the developmental pattern of UDP-glucuronosyltransferase, and the ontogenesis of glutathione-S-transferase activities differed according to the substrate metabolized.
12 citations
27 Jun 1988
TL;DR: The algorithm presented is designed to compute large degradable system reliability using nonrepetitive stochastic Petri nets using a criterion that allows the computation to be stopped as soon as a given precision is obtained.
Abstract: The algorithm presented is designed to compute large degradable system reliability. These systems are modeled using nonrepetitive stochastic Petri nets. The reliability parameters are computed during the generation of the reachability graph. A criterion is given that allows the computation to be stopped as soon as a given precision is obtained. >
11 citations
01 Nov 1988
TL;DR: In this article, the authors proposed a method for the deposition of organic conjugated polymers as thin films on semiconducting or conducting electrodes, in which the conductivity, catalytic activity and the hydrophobic character can be controlled.
Abstract: Organic conjugated polymers can be deposited as thin films on semiconducting or conducting electrodes, and, owing to the large potential offered by varying their physical and chemical properties, new devices can be envisionned. Thus CdS and CdSe are interesting photoanodes for the photoelectrochemical conversion and storage of light energy, but they require to be protected against their very fast corrosion in aqueous solution. This is achieved by thin layers of composite conducting polymers, in which the conductivity the catalytic activity and the hydrophobic character can be controlled. Besides, conjugated polymer films possess in their undoped state semiconducting properties, and when deposited on inorganic semiconductors, they lead to new “organic-on-inorganic” electronic junctions. The electric characteristics of these junctions can be easily tuned by subtle chemical modifications in the polymer structure and doping level. Finally, the recent development of functionalized organic conducting polymers, in which various prosthetic groups bearing selective functions are homogeneously distributed along the conducting chains, will allow the realization of new chemically selective electronic devices.
7 citations
TL;DR: The numero 10 de Techniques et Culture as discussed by the authors porte sur le meme theme that le numero precedent, and les articles qui y sont reunis font partie du meme ensemble.
Abstract: Le numero 10 de Techniques et Culture porte sur le meme theme que le numero precedent, et les articles qui y sont reunis font partie du meme ensemble. Leurs auteurs viennent des branches les plus diverses des sciences humaines. Mais on trouvera entre eux, me semble-t-il, sur le plan des concepts et des methodes, des convergences qui permettent d'esperer qu'en l'occurrence, l'interdisciplinarite n'aura pas ete un exercice aussi vain que d'habitude. Nous voyons avec notre cerveau autant qu'avec...
7 citations
TL;DR: Iron deficiency represented the most important cause of anaemia in the context of the authors' sample: iron deficiency contributed to 77% of anaemic women and folate deficiency and inflammatory processes do not in themselves appear to contribute to anaemia.
Abstract: Frequency of anaemia was estimated by two methods for 254 menstruating women living in South-eastern Algeria. One method defines the frequency of anaemia as the percentage of women with haemoglobin concentrations below the cut-off point defined by WHO (12 g/dl). The second method defines the frequency of anaemia as the percentage of women whose haemoglobin values are shifted downwards relative to a Gaussian distribution of haemoglobin of nonanaemic women. The conventional cut-off point probably tends to overestimate the true frequency of anaemia: 7% of women with haemoglobin concentration less than 12 g/dl were not found as anaemic using the cumulative frequency method. The contribution of iron deficiency folate deficiency and inflammatory process was estimated using the cumulative frequency distribution after excluding respectively women with biological evidence of iron deficiency (serum ferritin of 12 micrograms/l or less, transferrin saturation less than 15% and/or MCV less than 80 fl), of folate deficiency (red blood cell folates less than 100 micrograms/l) and of inflammatory process (C. Reactive Protein more than 12 mg/l, orosomucoid more than 1.4 g/l or white cell counts of more than 10,000/mm3). According to this method iron deficiency represented the most important cause of anaemia in the context of our sample: iron deficiency contributed to 77% of anaemia. Folate deficiency and inflammatory processes do not in themselves appear to contribute to anaemia.
TL;DR: In this article, the authors measured the Curie and crystallization temperatures Tc and Tx; Tc decreases when the concentration of M = Cr, V, Mo, Nb increases whereas this phenomenon is reverse for Ni.
Abstract: The ribbons we submitted to experiments correspond to the formula Fe79-xB16Si5Mx with X = 1, 2, 4, 6 at % and M = Cr, V, Mo, Nb, Ni. We measured the Curie and crystallization temperatures Tc and Tx; Tc decreases and Tx increases when the concentration of M = Cr, V, Mo, Nb increases whereas this phenomenon is reverse for Ni. In order to improve magnetic performances in the high frequency range, materials are annealed with an applied magnetic field along the ribbon axis. Losses are measured on straight or torus shaped samples in the frequency range from 10 kHz to 300 kHz. We observe a minimum of losses for all substitutions located close to 2 at %. We study the domain structure and it appears that the annealing treatment, when adjusted to loss minimization, induces small sized domains (about 10 μm).
Journal Article•
TL;DR: The photoemission yields of cesiated Ag films either annealed or coldly deposited were comparatively investigated and it is shown that the components of electromagnetic fields normal to the surface of cold films are not particularly high.
Abstract: The photoemission yields of cesiated Ag films either annealed or coldly deposited were comparatively investigated. The surface photoelectric effect was found to be the same for both samples in the spectral region where surface-enhanced Raman scattering at cold films was observed. We show that the components of electromagnetic fields normal to the surface of cold films are not particularly high.
TL;DR: In this article, the parametres de mise en oeuvre de polymeres semi-cristallins are modelled, and le comportement mecanique de ces materiaux est en relation etroite avec l'importance relative des different domaines structuraux.
TL;DR: In this paper, the attenuated total reflection changes induced by a submonolayer of caesium on silver are precisely analysed in the framework of the semiclassical anomalous skin effect theory.
TL;DR: In this article, the deexcitation of doubly excited N4+1s2ln'l') ions produced in N5+(1s 2s 3S) (3.4 keV amu-1)+He, H2 collisions has been studied in the 1-5 nm wavelength range and it is shown that the spectrum consists of lines mostly due to states produced by coreconserving capture processes except for an intense peak around 2.9 nm that could be due to electron capture with simultaneous 2s-2p core excitation.
Abstract: De-excitation of doubly excited N4+(1s2ln'l') ions produced in N5+(1s2s 3S) (3.4 keV amu-1)+He, H2 collisions has been studied in the 1-5 nm wavelength range. It is shown that the spectrum consists of lines mostly due to states produced by core-conserving capture processes except for an intense peak around 2.9 nm that could be due to electron capture with simultaneous 2s-2p core excitation. Moreover, many lines can be identified as originating from doublet states.
01 Jan 1988
TL;DR: A seminal paper published in Science, more than twenty-five years ago, for those who were then among the very few students of science and technology policy issues as discussed by the authors was one of the very first (and definitive) explanations of the brain drain.
Abstract: “Why did Daedalus leave?” was a seminal paper published in Science, more than twenty-five years ago, for those who were then among the very few students of science and technology policy issues (1). I remember well how impressed I was when I read it: this was one of the very first (and definitive) explanations of the brain drain. Stevan Dedijer had shown that such a process is the result more of repulsion than of attraction; scientists (and intellectuals at large) leave their country because they do not find satisfactory working conditions, or for political, ideological, economic or technical reasons, rather than for a preference to live abroad. Daedalus chooses to escape rather than to submit.
TL;DR: In 1970, Touloukian et al. as discussed by the authors introduced le parachor dans les grandeurs de reference, and the structure of the molecule was ainsi prise en compte.
TL;DR: In this article, Seguin et al. describe the naissance of the locomotive a chaudiere tubulaire (1828-1829) in the early 19th century.
Abstract: (1988). Seguin, Stephenson et la naissance de la locomotive a chaudiere tubulaire (1828–1829) History and Technology: Vol. 6, No. 2, pp. 145-171.
11 Feb 1988
TL;DR: A Software engineering workstation is presented which uses Modula-2 and a Prolog object-oriented extension called Modulog and it is also a basis for an original developer interface which make use of communication facilities between the two languages.
Abstract: A Software engineering workstation is presented which uses Modula-2 and a Prolog object-oriented extension called Modulog. Modulog offers the ability of declarative specifications interpretation and systematic module refinement. It is also a basis for an original developer interface which make use of communication facilities between the two languages.
TL;DR: This chapter discusses the design of technical systems and organization, and training of operators, and the concept of the course of action, which shares the hypothesis of the finalized organization of behavior that is common in psychology.
01 Jan 1988
TL;DR: In this article, a range of derivatives of aluminium phthalocyanine have been studied using pulsed laser excitation and measurements of fluorescence lifetimes determined using pulsED laser excitations are reported.
Abstract: Phthalocyanines are becoming increasingly recognised as important new photosensitisers for the photodynamic treatment of cancer1. These compounds with their extended conjugation absorb stongly near 700 nm which is a favourable property for this application. Investigations have largely concentrated on metallophthalocyanines as opposed to the free base since insertion of the appropriate metal (e.g. Al, Zn) increases the yield of the photo-active triplet state 2,3. Water solubility is conferred by the addition of ring substituents such as sulphonic acid groups, which may also influence localization properties in-vivo. This work is concerned with the study of a range of derivatives of aluminium phthalocyanine; measurements of fluorescence lifetimes determined using pulsed laser excitation are reported. Of particular interest is the sulphonated derivative (AlsPc) which has already been shown to be an effective photosensitiser in treating experimental tumours4. In the case of aluminium phthalocyanines a further variable is the extra-planar ligand attached to the central aluminium: not only can this ligand inhibit aggregation, it could also be used to influence in-vivo localization.
01 Jan 1988
TL;DR: Several column-switching configurations can be used for column switching as mentioned in this paper, including trace enrichment on a pre-column and automatic back-flush or forward-flush injection of the purified sample on an analytical column.
Abstract: Several possible configurations can be used for column-switching systems:
trace enrichment on a pre-column and automatic back-flush or forward-flush injection of the purified sample on an analytical column;
injection of the sample onto one column and automatic selection of a portion of the eluate (heart-cutting) for chromatography on a second column;
combination of these two systems: trace enrichment and heart-cutting. These approaches are briefly described for metoprolol, CGP 6140 and oxiracetam.