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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 93 (1989), S. 5623-5627 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Utilizing the magneto-optic Kerr effect (MOKE) in conjunction with x-ray and neutron reflectometry (NR) and diffraction, we have studied the magnetic coupling of Fe/Cr(001) superlattices grown at room temperature and 250 °C. Only the samples grown at elevated temperature exhibit noncollinear coupling of 5.0 nm Fe layers across 1.7 nm Cr interlayers. The noncollinear samples feature a less-disordered in-plane interfacial structure than those grown at room temperature. Using x-ray diffuse reflectivity, we have measured a length scale of 10 nm for these in-plane features. We have also observed, via NR, a remanent noncollinear coupling angle of 50° and, via MOKE and NR, a gradual approach to saturation at upwards of 7 kOe. These features can be explained qualitatively by the proximity magnetism model of Slonczewski. We will compare the predictions of both the proximity and bilinear/biquadratic models with our data and present the results of ongoing neutron measurements of the temperature dependence of the coupling. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 6432-6438 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Results are outlined of experimental work concerning Slonczewski's theories explaining 90° coupling: "loose spin'' theory and thickness-fluctuation mechanism. The loose spin theory suggests that 90° coupling originates from paramagnetic impurities in the interlayer of an exchange-coupled layered structure. The influence of these paramagnetic impurities on the magnetic exchange coupling was studied using the wedge technique. High-quality single-crystalline Fe/Ag/Fe samples were prepared in UHV and each sample consisted of two wedges: one wedge with additional Fe deliberately inserted during growth into the Ag interlayer and one wedge with a pure Fe/Ag/Fe structure. The detailed analysis of magneto-optic hysteresis loops revealed quantitatively the bilinearly and the 90° coupling strength. As predicted by loose spin theory additional Fe in the Ag spacer lead to a strong temperature dependence of the 90° coupling. According to the theory an increase of 90° coupling strength proportional to impurity concentration was detected while the strength of bilinear coupling decreased. For the pure Fe/Ag/Fe structure, a linear increase of the 90° coupling strength with decreasing temperature was observed. This result can be explained within the fluctuation mechanism which creates 90° coupling through a combination of interface roughness and intralayer ferromagnetic exchange. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Sensitivity to magnetic atoms and low intrinsic absorption characterize the interaction of neutrons with matter. Consequently, polarized neutron reflectivity provides a unique means of performing depth-resolved vector magnetometry. We have used this technique to determine the magnetization depth profiles of Fe/Cr superlattices. Superlattices of bilayer composition [55 A(ring) Fe/17 A(ring) Cr], grown at 523 K, exhibit biquadratic coupling with large saturation fields (∼3 kOe), while those grown at 293 K are ferromagnetically ordered. We have directly measured the evolution of the coupling angle between adjacent Fe layers as a function of applied field and will discuss how bilinear, biquadratic, and external field terms produce the observed order. The weaker coupling found in the Fe/Al system makes possible the investigation of a range of spin configurations at temperatures that do not endanger the sample. We have mapped the phase diagram of a [42 A(ring) Fe/12 A(ring) Al/39 A(ring) Fe] (100) trilayer and find evidence of biquadratic coupling at low temperatures and fields (e.g., when H=180 Oe, the Fe layer spins relax away from ferromagnetic alignment below T≈170 K). Our measurements agree qualitatively with energy minimization calculations and the results of bulk magnetometry.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The 2-ML (monolayer) oscillation period has been observed in the magnetization as well as in the magnetoresistance of Fe/Cr/Fe trilayers. Kerr effect measurements were performed in order to verify the periodicity and determine the kind of the coupling between the Fe layers. The magnetoresistance loops show characteristic steps at magnetic field values at which the size of the magnetization changes.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured the polarized neutron specular reflectivity of superlattices of nominal composition (5.0 nm Fe/1.7 nm Cr) grown by molecular-beam epitaxy. This chromium thickness lies at a minimum of the oscillatory bilinear (180°) coupling parameter, so these films are especially sensitive to biquadratic (90°) terms. One set of films was grown at a substrate temperature of 293 K and another at 593 K. Using neutron reflection, we find that the films grown at 523 K exhibit a 90° magnetic moment rotation between successive Fe layers, while the 293 K films are remanently ferromagnetically ordered in small applied fields (H=1.7 mT). Furthermore, we have observed that films grown at elevated temperature exhibit a larger amount of diffuse x-ray scattering due to conformal roughness than those grown at room temperature. These results suggest that the biquadratic coupling could be induced by the structure of the interfaces. We will also present the field and temperature dependence of the neutron reflectivity from the biquadratic films.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 85 (2003), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Neuroimmune interactions are discussed to drive neuropathic pain. We used the Bennett model to correlate pain and cellular expression profiles of the complement factors C1q and C1q-associated serine proteases C1r/C1s in lumbar spinal cord. At 2 days C1q mRNA levels increased ipsilateral to the lesion, and peaked at 8 days when allodynia and severe walking problems were present. During regeneration walking problems disappeared together with C1q mRNA levels. C1q biosynthesis was restricted to microglia. Surprisingly, C1s/C1r biosynthesis was not increased after injury suggesting a role for C1q different from classical complement activation. Sustained C1q expression in spinal microglia after lesion in conjunction with pain behavior indicates that microglial C1q may be causally involved in the development and maintenance of neuropathic pain.Acknowledgements:  Supported by BMBF01GG9818, SFB297, DFGWE910/8-3, KBN3P05C00623.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2479-2482 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Electrical resistivity measurements of materials as a function of pressure and temperature simultaneously are valuable indicators of structural phase changes and of electronic properties. Such measurements are difficult, however, and relatively few materials have been studied in this way. A sample holder for a tetrahedral anvil apparatus has been modified so that such measurements may be made. The calibration of the Pt/Pt10Rh thermocouple used to determine the temperature of the sample was found to be affected by pressure, and preliminary recalibration of this thermocouple under pressure was performed. Reasonable agreement was found between the phase diagram of CdTe determined with the apparatus used in this study and that previously published.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food quality 15 (1992), S. 0 
    ISSN: 1745-4557
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Tofu was prepared from samples of Amsoy 71 and Vinton or Vinton 81 soybeans grown in different environments. Relationships between soybean, soymilk and tofu protein, lipid, phytic acid, calcium, copper and iron were examined. All components except lipid in soybeans were significantly correlated with the same component in soymilk, but only phytic acid, copper and iron were significantly correlated in soybeans and tofu (moist basis). When relationships were examined on a dry basis, soybean and tofu protein were significantly correlated (r = 0.93).Soybean phytic acid was significantly correlated with tofu calcium (r = 0.90). Tofu calcium and hardness (r = 0.73) and springiness (r = 0.83). were significantly related, and tofu protein was significantly related to fracturability (r = 0.75).The higher-protein varieties (Vinton/Vinton 81) generally produced tofu that had a higher protein content and a firmer, more springy texture than that of the Amsoy 71 beans. Phytic acid may preferentially bind the calcium coagulant, altering the curd structure and the yield, composition and texture of the resulting tofu.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Peptides participating in the hypothalamic control of feeding behaviour are also involved in the central autonomic control of gastrointestinal functions, such as secretion and motility. An anatomical interaction and functional relationship in the central nervous system between the feeding-related peptides neuropeptide Y and ghrelin is well documented. Furthermore, it has been shown that feeding-related peptides can influence digestive function via central corticotrophin-releasing factor (CRF) pathways. In the present study, we investigated the role of ghrelin in the central autonomic control of colonic motility. Furthermore, we addressed the hypothesis that ghrelin is involved in the hypothalamic control of colonic motor function, utilizing central neuropeptide Y receptors and hypothalamic CRF pathways. Ghrelin (0.03, 0.06 and 0.12 nmol) bilaterally microinjected into the paraventricular nucleus (PVN) induced a significant stimulation of colonic propulsion. In particular, the colonic transit time decreased from 312 ± 7 min to 198 ± 12 min. Microinjection of the neuropeptide Y1 receptor antagonist, BIBP-3226 (200 pmol), or the nonselective CRF receptor antagonist, astressin (30 pmol), into the PVN abolished the stimulatory effect of ghrelin injected into the PVN on colonic transit time, whereas pretreatment with the selective CRF2 receptor, antisauvagine-30 (28 pmol), failed to affect the effect of PVN-ghrelin injection on colonic propulsion. These results suggest that ghrelin can act as central modulator of gastrointestinal motor functions at the level of the PVN via neuropeptide Y1- and CRF1 receptor-dependent mechanisms.
    Type of Medium: Electronic Resource
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