Plunger measurements on highly stripped O-ions as tool for detecting electron polarization on emergence from thin ferromagnetic layers

From hyperfine interaction studles on free single electron¹⁶O(3⁻) ions. in a time differential mode using the recoil distance technique. It is shown that these ions are polarized when emerging from magnetized thin layers of Fe. The observed degree of polarization , however, is smaller than expected from transient field measurements.     

An integrated organic photoconductive detector for optoelectronics

In the system (poly-(N-vinyl carbazole) (PVK): trinitrofluorenone (TNF) a photoconductive complex is formed. Thin metal films are sputtered on BK7 glass substrates, forming two electrodes with 1 mm separation. The photoconductive complex is deposited from a solution in chlorobenzene/tetrahydrofurane on the glass substrate between the electrodes, forming a photoconductive detector. Photoconductivity of these planar detectors is studied using He-Ne laser light (=633 nm) as a function of electric field and for different TNF concentrations. An increase of photosensitivity is found for high TNF concentrations.Time resolution of the photoconductive PVK:TNF detector is investigated using a ruby pulse laser (=694 nm). The possible use of such detectors in combination with other polymer lightguides is demonstrated. Compared to most polymer waveguide materials PVK exhibits a rather high refractive index ofn=1.7. Thus the coupling of light into the photoconductive film is achieved directly. The planar structure allows further integration of polymeric components for optoelectronics.     

The search for a new model structure of β-Factor XIIa

We present the search for a new model of -factor XIIa, a blood coagulation enzyme, with an unknown experimental 3D-structure. We decided to build not one but three different models using different homologous proteins as well as different techniques and different modellers. Additional studies, including extensive molecular dynamics simulations on the solvated state, allowed us to draw several conclusions concerning homology modelling, in general, and -factor XIIa, in particular.     

Self-terminating, oxidative radical cyclizations: a novel reaction of acyloxyl radicals.

Acyloxyl radicals RC(O)O* (with R = alkyl, aryl) could be trapped through addition to cyclic and open-chain alkynes, where they were found to act as a donor of oxygen atoms. Mechanistically, this radical oxygenation proceeded through a transannular or intramolecular, respectively, radical cyclization cascade, which was finally terminated by release of an acyl radical RC*(O). The reaction led to stereoselective formation of cyclized products, which contained a carbonyl group at the former site of the alkyne triple bond.     

Züchtung und Untersuchung von Einkristallen der Verbindungen CuCrZrSe4 und CuCrSnSe4

Preparation and Characterization of CuCrZrSe₄ and CuCrSnSe₄ Single Crystals Single crystals of the compounds CuCrZrSe₄ and CuCrSnSe₄ were grown by chemical transport using mixtures of AlCl₃/I₂ as transporting agents. Characterization of the crystals was done by X-ray methods. The compounds are normal spinels, the space group is Fd3m. The results of least squares refinement using single crystal X-ray data are reported.     

Röntgenographische,thermoelektrische, und IR-spektroskopische Untersuchung des Spinellsystems LixMn1−xV2O4

The spinels of the system Li_xMn_1?xV₂O₄ (0 ? x ? 1) have been prepared at 700–750°C from LiV₂O₄ and MnV₂O₄. The lattice constants decrease linearly with increasing x. In the region x>0.75, the d-electrons of V should be delocalized as the VV distances are lower than the critical VV separation of 2.94 Å. Experimentally, the samples with x>0.6 show no IR absorption bands and the Seebeck coefficient is near zero. The Seebeck coefficient can be described with a model of intermediate polarons and can be expressed by the equation $\text{Θ = 198}\text{log}\text{[1 +}\text{(1 ? x)}{}^5\text{x}\text{]}$.     

The 7‐bromo derivative of 2‐amino‐2′‐deoxytubercidin fluorinated at the sugar moiety

The title compound, 2,4‐diamino‐5‐bromo‐7‐(2‐deoxy‐2‐fluoro‐β‐d ‐arabinofuranosyl)‐7H‐pyrrolo[2,3‐d]pyrimidine, C₁₁H₁₃BrFN₅O₃, shows two conformations of the exocyclic C4′—C5′ bond, with the torsion angle γ (O5′—C5′—C4′—C3′) being 170.1 (3)° for conformer 1 (occupancy 0.69) and 60.7 (7)° for conformer 2 (occupancy 0.31). The N‐glycosylic bond exhibits an anti conformation, with χ = −114.8 (4)°. The sugar pucker is N‐type (C3′‐endo; ³T₄), with P = 23.3 (4)° and τ_m = 36.5 (2)°. The compound forms a three‐dimensional network that is stabilized by several intermolecular hydrogen bonds (N—H...O, O—H...N and N—H...Br).     

Zur Kinetik der Spinellbildung von β-Ga2O3 mit zweiwertigen Oxiden. IV. Reaktionen 2. Art im System CoO-β-Ga2O3

The solid-state reaction of the second kind in a sandwich type diffusion couple of $\text{Co}{}_{\mathrm{1?z}}\text{Ga}{}_{\mathrm{<mtext>2z</mtext><mtext>3</mtext>}}\text{O}$ and β-Ga₂O₃ has been investigated between 1249 and 1550°C in air. The quantity z, which corresponds to the saturation concentration of β-Ga₂O₃ in CoO, was determined as a function of temperature by X-ray methods and the optical microscope; the homogeneity range of the spinel phase $\text{Co}{}_{\mathrm{1?y}}\text{Ga}{}_{\mathrm{<mtext>2+</mtext><mtext>2y</mtext><mtext>3</mtext>}}\text{O}{}_4$ was investigated also. The growth of the thickness of the reaction layer follows a parabolic rate law; the activation energy is 71.6 kcal/mole. A comparison of reaction rate constants of the first and second kind in connection with experimental results, achieved with a modified marker technique, leads to confirmation of the Wagner mechanism for the formation of CoGa₂O₄ spinel as supposed before by Laqua. Reaction rate constants of the second kind, calculated from interdiffusion profiles in CoO-β-Ga₂O₃ diffusion couples, are in good agreement with experimental values. Presented data are used for estimating interdiffusion coefficients for the CoO-β-Ga₂O₃ system according to theoretical aspects developed by Pelton, Schmalzried, and Greskovich.