Synthesis of 3-methyl-2,3,4,4a,5,6-hexahydro-1H-benzofuro[3,2-e]isoquinoline-7(7aH)-ones

The 2,3,4,4a,5,6-hexahydro-1H-benzofuro[3,2-e]isoquinoline-7(7aH)-one ring system is prepared from a 4-arylpyridine precursor by sequentil intramolecular enolate addition to a pyridinium ion, Dieckmann cyclization, and catalytic hydrogenation.     

Kombinierter Nachweis von 14C-markierten Eiwei?stoffen und Aminos?uren nach S?ulen-Chromatographie an Sephadex

Zusammenfassung Es wird eine säulen-chromatographische Methode beschrieben, die mit kontinuierlich arbeitenden, registrierenden Meßgeräten gleichzeitig die UV-Absorption, die Radioaktivität und pH-Kurve von Aminosäuren, Peptiden und Proteinen zu erfassen gestattet. Nach Sammeln des Eluats in Fraktionen kann außerdem die Ninhydrinanfärbbarkeit der freie Aminogruppen enthaltenden Verbindungen gemessen werden. Hiermit ist auf einfache Weise die Möglichkeit gegeben, den Einbau von Prolin in Weizeneiweiß im Verlaufe der Reifung zu verfolgen.

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Combined detection of ¹⁴C-labelled proteins and amino acids after column chromatography on sephadex. II

With chromatography on gel columns a method has been developed which makes it possible to registrate continuously and simultaneously the UV-absorption, the radioactivity and the pH-curve of amino acids, peptides and proteins with an analyzing system. After the eluat has been collected in fractions the ninhydrin reaction can be carried out. In this way the incorporation of proline in wheat protein is measurable during ripening period in a simple way.

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Nr. 3209 der Veröffentlichungen der Bundesforschungsanstalt für Getreideverarbeitung.     

Die Sprungtemperatur von Supraleitern

An iteration procedure allows to find an equation for the critical temperatureT _c of superconductors starting from the linearized Eliashberg equations without using any cutoff parameters or a Coulomb pseudopotential. Explicit calculation ofT _c for a simple model leads to Morel, Anderson and McMillan's^1,2 expression thereby allowing for a physical interpretation of the commonly used approximation for the Coulombpseudopotential.     

X-Ray standing wave analysis of bismuth implanted in Si(110)

Perfect crystal silicon samples implanted with 60 KeV Bi atoms along the [110] surface normal direction were analyzed with X-ray standing waves. Two reflection orders, (220) and (440) were used with synchrontron radiation to study systematically the impurity distribution function at 5 different doses ranging from 0.6 to 10×10¹⁴ Bi atoms/cm². The analysis reveals the substitutional Bi position connected with a lattice expansion and the formation of precipitates at higher Bi doses as well as estimates for the Bi vibrational amplitude.     

Calibration of a Bonner sphere extension (BSE) for high-energy neutron spectrometry

In a recent work, we constructed modular multisphere system which expands upon the design of an existing, commercially available Bonner sphere system by adding concentric shells of copper, tungsten, or lead. Our modular multisphere system is referred to as the Bonner Sphere Extension (BSE). The BSE was tested in a high energy neutron beam (thermal to 800 MeV) at Los Alamos Neutron Science Center and provided improvement in the measurement of the neutron spectrum in the energy regions above 20 MeV when compared to the standard BSS (Burgett, 2008 and Howell et al., 2009).However, when the initial test of the system was carried-out at LANSCE, the BSE had not yet been calibrated. Therefore the objective of the present study was to perform calibration measurements. These calibration measurements were carried out using monoenergetic neutron ISO 8529-1 reference beams at the Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, Germany. The following monoenergetic reference beams were used for these experiments: 14.8 MeV, 1.2 MeV, 565 keV, and 144 keV. Response functions for the BSE were calculated using the Monte Carlo N-Particle Code, eXtended (MCNPX). The percent difference between the measured and calculated responses was calculated for each sphere and energy. The difference between measured and calculated responses for individual spheres ranged between 7.9 % and 16.7 % and the arithmetic mean for all spheres was (10.9 ± 1.8) %. These sphere specific correction factors will be applied for all future measurements carried-out with the BSE.     

Ultrafast dynamics of delocalized and localized electrons in carbon nanotubes

We report on the dynamics of the dielectric function of single-wall carbon nanotubes in the 10-30 THz frequency range after ultrafast laser excitation. The absence of a distinct free-carrier response is attributed to the photogeneration of strongly bound excitons in the tubes with large energy gaps. We find a feature of enhanced transmission caused by the blocking of optical transitions in small-gap tubes. The rapid decay of a featureless background with pronounced dichroism is associated with the increased absorption of spatially localized charge carriers before thermalization is completed.     

Large amplitude oscillations (switching) of bi-stable vortex structures in zero field

A ferromagnetic block (2a×2b×2c) with three unequal axes supports a vortex structure that intersects each of the two opposite surfaces of largest area. Swirls appear at points (xp, yp, c) and (?xp, yp, ?c) in state-A. In state-B the swirls are at points (?xp, ?yp, c) and (xp, ?yp, ?c). With micromagnetic simulations we demonstrate the possibility of a nucleation-free switching between those states, with possible applicability in devices. The oscillations are accompanied by large external fields from the magnetic charge at the core of the intersections of the vortices with the surface. These fields of the order of a quarter of the saturation inductance move over a distance 2xp～c in fractions of a ns.     

Self-affine convex polygons

A polygon in ${{\mathbb R}^2}$ is called self-affine if it can be dissected into k ≥ 2 affine images of itself. Self-affine convex polygons have at most five vertices. Triangles are trivially self-affine. It is shown that every convex quadrangle is self-affine, whereas only some, but not all convex pentagons are self-affine.