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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 7871-7883 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We introduce a one-electron pseudopotential model to study the structural and electronic properties of excess-electron alkali halide clusters. This model assumes total charge transfer between alkali and halide atoms. This ionic part of the system is described via repulsive and Coulomb potentials. The remaining electrons of the excess metal atoms are treated within an explicit quantal scheme via ion–electron pseudopotentials. Moreover, explicit core-polarization and core-electron correlation contributions are taken into account. This model is used to derive ground state structural, energetics, and electronic properties of one-excess electron NanFn−1 clusters in the range 2≤n≤29. We show that the structural characters are closely related with electron localization and we propose a classification into five types, two of them exhibiting rather strong localization namely F-centers and Na-tail structures, the others exhibiting a less bound electron localizing in a surface-state, an edge-state, or on an atom-depleted face of the cluster. Although we observe an energetical predominance of cubiclike structures, hexagonal isomers are seen to appear as stable ones and exhibit similar localization features. The various energy contributions to the stability are examined. All studied NanFn−1 clusters are found stable with respect to fragmentation. The ionization potentials, which are seen to reflect faithfully the localization character, are discussed in details and compared with consistent recent experimental data. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    International journal of cosmetic science 5 (1983), S. 0 
    ISSN: 1468-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: La glande sébacée est une structure androgéno-dépendante et un site majeur pour le métabolisme des androgènes. Par ailleurs, on sait que les androgènes sont largement impliqués dans la stimulation de la sécrétion sébacée chez l'homme. L'objet de ce travail est ainsi de contribuer à l'étude du rôle de ces hormones et de leurs métabolites dans la séborrhée et de commenter l'activité locale de certains inhibiteurs.Les méthodes utilisées mesurent les paramètres suivants: la sécrétion sébacée et la synthèse des lipides sébacés marqués au carbone-14 chez l'animal, le métabolisme d'androgènes marqués dans la peau de l'animal et de l'homme.Nos résultats montrent:– en administration sous cutanée chez le rat, il existe une spécificité relative des androgènes faibles (type DHA) pour la glande sébacée contrairement aux androgènes puissants (type testostérone);– par voie locale chez le hamster, la 5α-DHT est plus active pour stimuler la lipogénèse sébacée que la testostérone et les dérivés 17β-OH sont plus actifs que les dérivés 17-cétones;–in vitro, la synthèse des lipides sébacés n'est pas associée à des changements profonds des voies métaboliques habituelles des androgènes dans l'organe cible;– sur la base de cette expérimentation certains antiséborrhéiques potentiels ont étéétudiés.L'ensemble de ces résultats sera discuté en fonction de leurs implications éventuelles en cosmétologie, particulièrement au niveau du problème des peaux grasses.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    International journal of cosmetic science 4 (1982), S. 0 
    ISSN: 1468-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Après avoir rappelé brièvement le spectre d'action biologique du rayonnement ultraviolet du soleil sur la peau normale et les données theoriques de protection qui en découlent, le caractère prévisionnel de différentes méthodes d'étude in vitro et in vivo des antisolaires est commentéà partir de résultats obtenus en laboratoire sur différents principes actifs (PABA, Eusolex 4360, Giv Tan F), et préparations cosmétiques du commerce.Les méthodes in vitro, basées sur l'absorption dans l'UV des produits, aboutissent à une protection surévaluée et dans ces conditions à une extrapolation trés aléatoire du pouvoir de protection.La méthode utilisée in vivo (détermination classique d'un indice de protection) souligne, dans le cadre de la prédiction, le choix de la qualité d'absorption du filtre, de la source UV utilisée, mais aussi de nombreux autres facteurs agissant sur la protection. Dans ces conditions, les résultats obtenus chez le cobaye et l'homme avec des irradiations simulant le spectre solaire, montrent alors une concordance satisfaisante pour les principes actifs étudies. Ces observations sont ensuite commentees par comparaison à d'autres travaux publiés faisant mention d'autre source d'irradiation (spectre de raies) et de méthode de détection (thermométrique en particulier). Predictive nature of laboratory methods in sunscreen studies
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    International journal of cosmetic science 2 (1980), S. 0 
    ISSN: 1468-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: L'analyse des résultats obtenus pour certains antiseborrheiques, avec differentes methodes d'étude expérimentale, a conduit à se poser le problème du caractère prévisionnel à l'homme de ces méthodes.L'utilisation des estrogènes dans la séborrhée se trouve largement justifiée par des essais chez l'animal dans lesquels des dérivés estrogéniques puissants (ethynyl estradiol,…) ont un reel effet par voie générale tant sur la cible sébacée que sur les organes sexuels. Une spécificité plus particulière pour la glande sébacée a été reconnue par contre à d'autres dérivés moins puissants (promestriène, CM 4727). Par voie topique, cette justification est discutable.Parmi les anti-androgènes, l'activité par voie générale des produits de type acetate de cyprotérone est bien mise en évidence, tant au niveau de la sécrétion sébacée qu'au niveau des mitoses, chez l'animal comme chez l'homme. Cet effet n'est guère retrouvé par voie topique chez l'homme, même à très forte concentration. En ce qui concerne la progestérone, une etroite correlation existerait entre l'animal et l'homme au niveau de la dissociation de l'effet anti-séborrhéique local suivant le sexe.Enfin, les produits non hormonaux décrits comme anti-séborrhéiques chez l'homme (clofibrate, dérivés de la cystéine, acide eicosa tétraynoïque) posent sur le plan expérimental de nombreux problèmes pour mettre en évidence leur activité.Cette étude de corrélation confirme ainsi que la prédiction de l'activité des antiséborrhéiques de l'animal à l'homme est loin d'être aisée et que le choix du modèle animal prend une valeur toute particulière en fonction de la molécule àétudier. Predictable nature of the laboratory investigation methods of anti-seborrhoeic drugs 〈section xml:id="abs1-2"〉〈title type="main"〉SummaryThe aim of this work is to evaluate the predictable nature in human therapeutics of results obtained with some anti-seborrhoeic drugs in various experimental tests performed in vitro or in vivo on animal models. This correlative study applies to anti-seborrhoiec drugs (mainly of the hormonal type) for which the results of tests based on objective measurement criteria (secretion of sebum, synthesis of sebaceous lipids, height and mitoses number of sebaceous gland) are available in the animal as well as in man (literature references or assays performed in our laboratory).Natural or more often synthetic oestrogens are currently used in women with seborrhoea or acne, as an oral contraceptive drug and, more recently, as a local therapy in both sexes. Benefits of such utilisation have been well assessed by assays on animal models in which powerful oestrogen derivatives (ethinyl estradiol, diethylstilboestrol) are actually active by systemic administration on the sebaceous target as well as on the sexual organs. Nevertheless a more specific action on the sebaceous gland has been found for other less powerful estrogen derivatives (promestriene or CM 4727). The topic use may yet be criticised because the inhibition observed in the animal is usually a systemic one and, on the other hand, depending on the animal chosen and its sex, the results may not be in agreement with those described for human tests.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 1560-1567 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: 120 keV carbon ions implantations at high fluences (0.5–8×1017 ions cm−2) were performed at elevated temperature (≥500 °C) in silver layers deposited on various substrates (Si (100), 304 L stainless steel, and pure fused silica). Spherical carbon onions (3–15 nm in diameter) were so produced in the silver layers. A pure carbon onion thin film deposited on the substrate was obtained after annealing in vacuum. Atomic force microscopy and high-resolution transmission electron microscopy experiments were performed to characterize the structure of the thin films. Optical transmittance spectra of carbon onion layers deposited onto silica substrates revealed two absorption peaks centered at 220–230 nm and at 265 nm that were attributed to the presence of carbon onions and residual disordered graphitic carbon, respectively. Tribological experiments performed on silver–carbon onions composite thin films revealed that the friction coefficient is close to that of a pure silver film (0.2) but with much better wear behavior. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The spread of Sugarcane yellow leaf virus (SCYLV) in sugarcane plants was studied on Réunion using virus-infected cuttings from four cultivars (R570, R575, R577 and R579). One month after the germination of cuttings in an insect-proof glasshouse, SCYLV was detected by reverse-transcription polymerase chain reaction (RT-PCR) and tissue-blot immunoassay (TBIA) in the leaves, shoots and roots of all cultivars. The distribution of SCYLV in the whole plant did not vary over a 10- to 11-month period of growth. In addition, the spread of SCYLV in sugarcane fields on Réunion was investigated during a survey conducted from 1998 to 2001. Samples were taken in three sugarcane-growing areas, and TBIA was used to detect SCYLV in the three major cultivars (R570, R575 and R579). The percentage of infected stalks varied according to cultivar and growing area, but remained relatively stable for a given cultivar in a given growing area over the 30-month survey period. Cultivar R575 was the most infected cultivar in all three growing areas (mean of 98% infected stalks). The percentage of infected stalks ranged from 16 to 94% in cv. R570 and from 21 to 92% in cv. R579. These results suggested that on Réunion: (i) infected sugarcane stools do not recover from the disease after harvesting; and (ii) the virus is mainly propagated by planting infected cuttings. SCYLV was detected by RT-PCR in the aphid Melanaphis sacchari, a potential vector of this virus. Two months after planting virus-free plants of susceptible cv. R575 in a field surrounded by sugarcane infected with SCYLV, 14% of plants were found infected with the virus. Four months later, 25% of plants were found infected with SCYLV, but no new infections were detected between 6 and 12 months after planting. In the first ratoon crop, 42% of plants were infected with SCYLV after 6 months of growth. Spatial distribution of infected plants suggested that, on Réunion, a small window of time (between 0 and 2 months after planting cuttings) exists during which primary infection can occur. Based on the results obtained in this study, the use of clean planting material for some cultivars and the use of tolerant cultivars should be an efficient means of controlling sugarcane yellow leaf on Réunion.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Allergy 47 (1992), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This study describes an in vitro method to evaluate a PAF acether release test (PART) from white blood cells after antigenic challenge. PAF acether activity of the supernatant was tested by platelet aggregation. The aggregating power was abolished by using SRI 63-441 (Sandoz), a PAF acether inhibitor. This method was applied to 57 patients with allergic or pseudo-allergic reactions to drugs by using different drug protein conjugates. The results of PART were evaluated in relation to the clinical history (score of imputability) and to other tests (skin tests, lymphocyte transformation tests (LTT), igE-RAST). A good correlation was found between the release of PAF acether and a high predictability score: sensitivity 75%, specificity 83.8%. PART also correlated with skin tests (75% agreement, n= 60), with LTT (67.7% agreement, n= 74) and in 65.6% of cases with positive penicillin IgE-RAST (n= 32). This method brings a new possibility for the investigation of drug-allergic and pseudo-allergic reactions.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Allergy 41 (1986), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Studies made in our laboratory have demonstrated the presence in atopic serum of enhancing factors(s) for in vitro IgE synthesis by peripheral blood lymphocytes (BPL). Here we show that these enhancing factors can be recovered from human serum by means of immunoabsorbents. This factor is able to stimulate in vitro IgE synthesis by PBL independent of presence of IgE.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Allergy 30 (1975), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1751-908X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: This paper reports the results from a second characterisation of the 91500 zircon, including data from electron probe microanalysis, laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS), secondary ion mass spectrometry (SIMS) and laser fluorination analyses. The focus of this initiative was to establish the suitability of this large single zircon crystal for calibrating in situ analyses of the rare earth elements and oxygen isotopes, as well as to provide working values for key geochemical systems. In addition to extensive testing of the chemical and structural homogeneity of this sample, the occurrence of banding in 91500 in both backscattered electron and cathodoluminescence images is described in detail. Blind intercomparison data reported by both LA-ICP-MS and SIMS laboratories indicate that only small systematic differences exist between the data sets provided by these two techniques. Furthermore, the use of NIST SRM 610 glass as the calibrant for SIMS analyses was found to introduce little or no systematic error into the results for zircon. Based on both laser fluorination and SIMS data, zircon 91500 seems to be very well suited for calibrating in situ oxygen isotopic analyses.
    Type of Medium: Electronic Resource
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