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  • 1
    Electronic Resource
    Electronic Resource
    Magnetizability of Nd-Fe-B-type magnets with Dy additions (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 3510-3512 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Many alloying additions have been made into Nd-Fe-B-type magnets to alter their permanent magnet properties, in particular for applications above 100 °C. To this end, a common practice has been to add Dy, increasing Hci [M. Sagawa, S. Fujimura, H. Yamamoto, H. Matsuura, and K. Hiraga, IEEE Trans. Magn. 20, 1584 (1984); M. Tokunaga, M. Meguro, M. Endoh, S. Tanigawa, and H. Harada, ibid. 20, 1964 (1985)]. It is not unusual to find Hci 〉20 kOe in these substituted alloys. This approach has caused a dilemma. In some cases, increasing Hci above 20 kOe makes the alloy more difficult to magnetize and therefore less useful when the field available for magnetizing is 25 kOe or less. We have examined the effect of various alloying additions and heat treatment on the magnetizability of substituted Nd-Fe-B alloys. We show that high Hci at room temperature is not a necessary requirement to have Hci 〉6 kOe at 150 °C. We discuss the factors affecting the magnetizability of Nd-Fe-B-type magnets.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.340725
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  • 2
    Electronic Resource
    Electronic Resource
    Phorbol ester does not mimic, but antagonizes the alpha-adrenoceptor-mediated positive inotropic effect in the rabbit papillary muscle (1988)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 337 (1988), S. 169-176 
    Details
    ISSN: 1432-1912
    Keywords: Phorbol ester ; Protein kinase C ; alphaAdrenoceptors ; beta-Adrenoceptors ; Positive inotropic effects ; Phenylephrine ; [3H]prazosin binding ; [3H]CGP-12177 binding ; Rabbit papillary muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The phorbol ester 12-O-tetradecanoyl phorbol-13-acetate (TPA) was used to examine the hypothesis that phosphoinositide turnover is involved in the regulation of myocardial contractility mediated by stimulation of alpha-adrenoceptors in the mammalian cardiac muscle. Exposure of the isolated rabbit papillary muscle electrically driven at a rate of 1 Hz at a temperature of 37°C to TPA in concentrations of 10–1000 nmol/l for 30 min did not affect the basal force of contraction. The concentration-response curve for the positive inotropic effect of (−)-phenylephrine mediated by stimulation of alpha-adrenoceptors in the presence of (±)-bupranolol (100 nmol/1) was shifted to the right and downward by TPA in concentrations of 30–1000 nmol/l, while the effect of (−)-phenylephrine mediated by stimulation of beta-adrenoceptors in the presence of prazosin (100 nmol/l) was not decreased, but slightly enhanced by exposure of the muscle to relatively low concentrations of TPA (10–100 nmol/l). Incubation of the membrane fraction isolated from the rabbit ventricular muscle with TPA in vitro under the same condition as employed in the physiological experiments decreased the specific binding of [3H]prazosin but not that of [3H]CGP-12177, while the non-tumor promoting phorbol ester, αPDD, was ineffective. These results indicate that activation of protein kinase C by TPA does not mimic the positive inotropic effect of catecholamines mediated by activation of myocardial alpha-adrenoceptors. on the other hand, the specific interaction of alpha-adrenoceptor-mediated processes with TPA in the rabbit papillary muscle is in line with the view that the facilitation of phosphoinositide turnover and subsequent activation of protein kinase C may play a certain role in the coupling of alpha-adrenoceptor occupation by agonists to the process leading to the positive inotropic action.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169245
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  • 3
    Electronic Resource
    Electronic Resource
    Preponderance of β- over α-adrenoceptors in mediating the positive inotropic effect of phenylephrine in the ferret ventricular myocardium (1989)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 339 (1989), S. 362-366 
    Details
    ISSN: 1432-1912
    Keywords: α-Adrenoceptors ; β-Adrenoceptors ; Positive isotropic effect ; Phenylephrine ; Ferret ventricular myocardium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary [3H]prazosin bound to the membrane fraction derived from the ferret ventricular muscle with high affinity in a saturable manner (K d = 0.25 nmol/l and B max = 27 fmol/mg protein in the right ventricle). [3H]CGP-12177, a β-adrenoceptor ligand, bound to the membrane fraction with a K d value of 0.29 nmol/l and a B max of 42 fmol/mg protein. In the isolated ferret papillary muscle driven at 1 Hz at 37°C, phenylephrine elicited a concentration-dependent positive intropic effect. The maximal effect of phenylephrine was comparable to that of isoprenaline. Prazosin (0.3 μol/l) shifted the concentration-response curve for phenylephrine slightly but significantly to the right, the maximal response being unaffected. In contrast, bupranolol (0.3 gmol/l) shifted the curve for phenylephrine markedly downwards: the maximal response was depressed significantly to 40% and the curve became less steep. In the presence of prazosin and bupranolol the curve was shifted to the right, being essentially parallel to the control curve. These results indicate that in the ferret ventricular myocardium both α- and β-adrenoceptors mediate the positive inotropic effect of phenylephrine. The extent of contribution of the two classes of adrenoceptor is quite different from that in other mammalian species. In the ferret heart, β-adrenoceptors predominate over α-adrenoceptors in mediating the positive inotropic effect of phenylephrine, although the number of β-adrenoceptors is not especially high when compared with other species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173593
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