Bibliothek

Sie haben 0 gespeicherte Treffer.
Markieren Sie die Treffer und klicken Sie auf "Zur Merkliste hinzufügen", um sie in dieser Liste zu speichern.
feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Molecular and cellular biochemistry 209 (2000), S. 55-61 
    ISSN: 1573-4919
    Schlagwort(e): glutathione depletion ; reactive oxygen species ; antioxidants ; oxidative damage ; diethylmaleate ; phorone ; brain ; rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract This study was aimed to evaluate the oxidative damage, production of reactive oxygen species and the status of antioxidative defenses following cerebral GSH depletion induced by two classical depletors, diethylmaleate (DEM, 3 mmol/kg, i.p.) and phorone (PHO, 4 mmol/kg, i.p.). The treatment decreased (40-43%) brain glutathione levels at 2 h, followed by a partial recovery at 24 h. Cerebral glutathione depletion by these agents increased the levels of superoxide anion and hydroxyl radical at both the time intervals; however, hydrogen peroxide was high at 24 h only. It also produced a dramatic increase in the protein carbonyls at 2 h but not at 24h, without any significant effect on lipid peroxidation and conjugated diene levels. These rats showed a significantly lowered superoxide dismutase activity both at 2 h and 24 h of exposure, as compared to controls. Glutathione depletion enhanced catalase activity markedly at 2 h, followed by some recovery at 24 h. While Se-independent glutathione peroxidase (GPx) and glutathione S-transferase activities were increased at both 2 and 24 h time intervals, Se-dependent GPx and glucose-6-phosphate dehydrogenase were induced at 2 h only. Glutathione depletion decreased ceruloplasmin and vitamin E levels significantly at 2 h. However, ascorbic acid remained unaffected. It may be concluded that an acute cerebral glutathione depletion generates higher levels of reactive oxygen species, which may be responsible for oxidative modification of proteins. Some of these changes appear to recover soon after an activation of a variety of cellular antioxidant defense mechanisms and glutathione restoration. It appears that central nervous system is highly vulnerable to oxidative damage following a moderate glutathione depletion that may result from certain diseases or xenobiotic exposures.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Journal of medicinal chemistry 15 (1972), S. 999-1000 
    ISSN: 1520-4804
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 513-517 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The plasma produced during pulsed laser deposition of manganate films has been probed using optical emission spectroscopy. The studies have been carried out using Mn, Mn2O3, and La0.67Sr0.33MnO3 (LSMO) as target materials in the presence of two different oxidizing gases: nitrous oxide (N2O) and oxygen (O2). Emission from excited MnO (MnO*) has been observed in all cases resulting primarily from reaction of the ablated Mn atoms with the background gas. Consistent with the oxidation reaction energetics, the emission intensity from MnO* is found to be about an order of magnitude stronger with N2O than with O2. Magnetization measurements of LSMO films show improved magnetic properties of films prepared in N2O compared to O2 at low pressures. The improvement in film quality can be attributed, at least in part, to the increased oxidation of Mn in the plasma plume. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 2807-2816 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The pulsed laser deposition technique has been used to study the process of layering and intermixing of precursor oxide phases of YBa2Cu3O7−δ (YBCO) during deposition from separate component targets. The films are grown on (100)-oriented SrTiO3 substrates by ablation from the component targets YBa2Ox/CuO or Y2Cu2O5/BaCuO2 under process conditions similar to those needed for the growth of YBCO films from a composite target. For precursor oxide layers below a critical thickness, which can be as large as 1000 A(ring), facile formation of high-quality epitaxial YBCO films is observed resulting from interdiffusion and reaction of the constituent phases. On the other hand, while some degree of intermixing occurs above the critical thickness, there is no evidence of formation of the YBCO phase. The novel solid-phase epitaxy observed below the critical thickness is believed to result from diffusion of species through grain boundaries of the initial precursor oxide layer, followed by reaction at the substrate interface to epitaxially nucleate the YBCO layers. The process continues until all of the initial oxide layer is consumed and can be repeated with deposition of subsequent alternate layers. The dynamics of the diffusion process has been investigated using in situ resistance measurements to monitor the growth of the YBCO phase. The results show that the time scale for interdiffusion and reaction is very rapid (∼10–100 ms), and occurs soon after arrival of the ablated species from the second component target on the surface of the initial precursor oxide layer. These results have important implications for the choice of component oxide blocks for layer-by-layer growth of artificially structured films.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 5
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 5343-5343 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Recent progress in oxide perovskite thin-film technology has led to the discovery of a large negative magnetoresistance at room temperature in the doped manganate perovskite thin films. For applications such as magnetic-field sensing, the saturation magnetic field for large magnetoresistance has to be significantly lowered. The magnetic and transport properties of the doped manganates involve a curious magnetic-field scale, on the order of 1–10 T. Upon the application of a field on this scale, the magnetoresistance saturates, and a significant broadening of the temperature-dependent magnetization is seen. An understanding of the materials physics that underlie such behavior can point to new ways of lowering the saturation field in this class of materials. We argue that this characteristic field is suggestive of an inhomogeneous magnetic state in the system. We will discuss the basic phenomena and physics of magnetotransport in this class of materials. We will also report the successful fabrication of a trilayer thin-film pillar structure made using the doped manganate perovskites in which a magnetoresistance change by about a factor of 2 was observed at temperatures below 100 K in a field less than 200 Oe, proving that large magnetoresistance in low field can be obtained in these materials. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 6
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Epitaxial thin films of La1−x(D'Alembertian)xMnO3−δ(0≤x≤0.33) where (D'Alembertian) is a vacancy have been grown on (100) SrTiO3 substrates by pulsed laser deposition. The lanthanum deficiency results in self doping of the system without the need for divalent ion substitution. Both the films and the bulk targets used for deposition were ferromagnetic and showed giant magnetoresistance (GMR). The films increased in saturation magnetization Ms and Curie temperature Tc with increasing x. The Tc, however, was about the same as found in Cax substitutions. Bulk samples showed little change in Ms and Tc with vacancy concentration. Ms in bulk samples is about half the value found in the films which have theoretical saturations for x≥0.2. GMR in the films is a few hundred percent but the bulk values are 25% at H=1.8 T. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 7
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 4538-4540 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have explored the colossal magnetoresistance (CMR) effect in the antiferromagnetic La0.5Ca0.5MnO3 compound. In the absence of a magnetic field (H), the solid is a canted antiferromagnetic (AFM) insulator. An applied H in the Tesla scale induces a first order AFM to FM phase transition, and correspondingly, an insulator to metal transition. The observed CMR is attributed to the H-induced charge localization-delocalization behavior associated with the AFM–FM transition. At low temperatures (T〈100 K), the solid remains in the AFM phase, where we have observed a phenomenal one millionfold change in resistivity between 0 and 8 Tesla. The origin of CMR in low T-region is a thermal activation energy gap which is strongly dependent on H. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 8
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have fabricated epitaxial La0.67Ca0.33MnO3−δ thin films using pulsed laser deposition and performed subsequent thermal treatments. Magnetoresistance values as large as 14 000% (Δρ/ρH) were obtained. Above magnetic ordering temperatures, we observed a thermally activated conductivity that also has a quadratic magnetic field dependence. At low temperatures, we found a large hysteresis in the magnetoresistance that correlates with an unusual magnetic hysteresis curve. We interpret the hysteretic behavior as the result of a "frozen-in'' canted spin structure. Our results suggest that the electron conduction in this material is most sensitive to the canting angle of the neighboring Mn spins. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 9
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 85 (1978), S. 0 
    ISSN: 1471-0528
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: The percentage of T-cells was studied in pregnant patients with a previous history of spontaneous abortions, in patients without such a history and in nonpregnant controls. The percentage of T-cells remained unaltered during the three trimesters of normal pregnancy. In patients with a previous history of spontaneous abortions, the T-cell percentages were lower in the second and third trimesters than in non-pregnant controls, but the values did not differ statistically from corresponding values in those patients with no previous history of spontaneous abortion (normal pregnancy). The phytohaemagglutinin (PHA)-induced transformation of lymphocytes was depressed in the second and third trimesters of both patients with a normal pregnancy and those with a previous history of spontaneous abortions. Thus, while the percentage of T-cells remained unaltered during pregnancy, their response to PHA falls in the second and third trimesters.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 10
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Langmuir 9 (1993), S. 1786-1793 
    ISSN: 1520-5827
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...