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R Schlueter

Publications and source records attributed to R Schlueter.

3 recordsLinked to original sources
PubMed2002

Variable linear polarization from an X-ray undulator.

A new X-ray undulator has been designed and constructed which produces linearly polarized X-rays in which the plane of polarization can be oriented to a user selectable angle, from horizontal to vertical. Based on the Apple-II elliptically polarizing undulator (EPU), the undulator rotates the angle of the linear polarization by a simple longitudinal motion of the undulator magnets. Combined with the circular and elliptical polarization capabilities of the EPU operating in the standard mode, this new undulator produces soft X-ray radiation with versatile polarization control. This paper describes the magnetic structure of the device and presents an analysis of the magnetic field with varying undulator parameters. The variable linear polarization capability is then exhibited by measuring the X-ray absorption spectrum of an oriented polytetrafluoroethylene thin film. This experiment, which measures the linear dichroism of the sample at two peaks near the C 1s absorption edge, demonstrates the continuous polarization rotation capabilities of the undulator.

Journal Article↗
PubMed1981

Specific binding of 125I-salmon calcitonin to rat brain: regional variation and calcitonin specificity.

Rat brain particulate fraction was found to contain binding sites for 125I-Salmon Calcitonin-I (125I-SCT). Maximum binding occurred in the physiological pH range of 7.25-7.5. The binding reaction proceeded in a temperature-dependent manner. Binding sites were broadly distributed among the various rat brain regions and considerable regional differences existed in the affinity and density as detected by Scatchard analysis. The highest affinity was recorded in the case of the hypothalamus and the lowest in the case of the cerebellum. The KD (nM) and Bmax (pmole/mg protein) estimated for the binding to four regions were as follows: hypothalamus: 1.4 and 0.19, midbrain, hippocampus plus striatum: 1.5 and 0.08, pons plus medulla oblongata: 3.0 and 0.15 and cerebellum: 8.3 and 0.20. Using a particulate fraction of rat brain void of cerebellum and cortices, a binding assay for calcitonins was developed. Binding of 125I-SCT was inhibited by unlabeled salmon, [Asu1,7]-eel and porcine calcitonins in a dose-dependent manner and the IC50s were 2.0, 8.0 and 30 nM, respectively. The IC50s were comparable to those estimated using a kidney particulate fraction. Human calcitonin, beta-endorphin and substance P were weak inhibitors of the binding. Other peptides, drugs and putative neurotransmitters tested (totally 23 substances) failed to inhibit the binding at concentrations of 1.0 microM. The physiological significance of brain binding sites for calcitonin, with the possibility that the brain may possess endogenous ligands for these sites are discussed.

Animals↗