Bestimmung von Stickstoff in Sojabohnenmehl und Rapssamenkuchen

Ohne Zusammenfassung     

Relative equidimensionality and stability of actions¶of a reductive algebraic group

In order to inquire into invariants of non-semisimple groups, we introduce and study relative versions of equidimensionality and stabilty, which are called relative quasi-equidimensionality and relative stability, of actions of affine algebraic groups, especially of reductive groups, on affine varieties. As an application of our results, for complex reductive groups of semisimple rank one, we characterize, respectively, relatively stable representations and relatively equidimensional representations and, consequently, show that every equidimensional representation is cofree. Received: 23 October 1998     

Effect of wind-generated waves on the transfer of solar radiation in the atmosphere-ocean system

Transfer of solar radiation in the combined atmosphere and ocean system is evaluated by the matrix operator method. Derivation of the reflection and transmission matrices required for applying the matrix method is discussed introducing the shadowing effect of light by the ocean waves. Spectral and total radiation fields just above and below the ocean surface, as well as the top of the atmosphere, are numerically calculated using several optical models of the atmosphere, ocean, and wind roughened ocean surface. Dependencies of radiance and flux reflectivity on the wind velocity and optical property of the ocean body are discussed in detail.     

Effect of Dissolved Oxygen on the Reduction of Stable Nitroxide by Ascorbic Acid: In Vitro Model for Acute Hypoxia Ischemia

The reaction between 3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (PCAM), which is a blood–brain-barrier (BBB) permeable stable cyclic nitroxide, and ascorbic acid was examined in a low dissolved oxygen-phosphate buffer (low DO-PB, 0.1 mM DO) under 8% oxygen in a glove bag or in an ordinal dissolved oxygen-phosphate buffer (ordinal DO-PB, 0.3 mM DO) under 21% oxygen in an open atmosphere with and without diethylenetriaminepentaacetic acid (DTPA). In PB with DTPA, no difference was observed between the results in the low DO-PB and those in the ordinal DO-PB. In the ordinal DO-PB without DTPA, the rate constant of the PCAM decrease was half that in the low DO-PB without DTPA. The present results indicate that high DO and coexisting transition metal ions caused the oxidation of ascorbic acid, which degraded the PCAM reduction. The stable nitroxide-ascorbic acid system without DTPA was found to be applicable to an in vitro model for the acute hypoxia ischemia.     

Surface structures of equimolar mixtures of imidazolium-based ionic liquids using high-resolution Rutherford backscattering spectroscopy

Surface structures of equimolar mixtures of imidazolium-based ionic liquids (ILs) having a common cation (1-butyl-3-methylimidazolium ([C₄MIM]) or 1-hexyl-3-methylimidazolium ([C₆MIM])) and different anions (bis(trifluoromethanesulfonyl)imide ([TFSI]), hexafluorophosphate ([PF₆]) or chlorine) are studied using high-resolution Rutherford backscattering spectroscopy (HRBS). Both cations and anions have the same preferential orientations at the surface as in the pure ILs. In the mixture, the larger anion is located shallower than the smaller anion. The [TFSI] anion is slightly enriched at the surface relative to [PF₆] with coverage of ~ 60% for the equimolar mixtures of [C₄₍₆₎MIM] [TFSI] and [C₄₍₆₎MIM] [PF₆]. No surface segregation is observed for [C₆MIM] [TFSI]_0.5[Cl]_0.5 and [C₆MIM] [PF₆]_0.5[Cl]_0.5. These results are different from the recent TOF-SIMS measurement where very strong surface segregation of [TFSI] was concluded for the mixture of [C₄MIM] [TFSI] and [C₄MIM] [PF₆].     

Oxidation behaviour of Ni nanoparticles and formation process of hollow NiO

The oxidation behaviour of Ni nanoparticles at temperatures from 573 to 673 K and the formation process of hollow oxide particles were studied by transmission electron microscopy. In the course of oxidation, a single large void was observed at one site of the interface between inner Ni and outer NiO layer due to vacancy clustering, which occurs during the oxidation process resulting from the rapid outward diffusion of Ni ions through the NiO layer. This suggests that supersaturated vacancies generated at the interface migrate to the site over a long-range distance and aggregate at the site. Ni nanoparticles were fully oxidized to become hollow NiO, in which nano-holes in the form of vacancy clusters were located at the off-centred positions. The de-centring of the voids in hollow NiO is probably due to the large mobility of vacancies inside Ni during oxidation.     

Soft-landing isolation of vanadium-benzene sandwich clusters on a room-temperature substrate using n-alkanethiolate self-assembled monolayer matrixes

Gas-phase synthesized vanadium-benzene 1:2 (VBz(2)) sandwich clusters were size-selectively deposited onto bare gold and long-chain n-alkanethiolate [-S-(CH(2))(n-1)-CH(3); n = 16, 18, and 22] self-assembled monolayer (SAM)-coated gold substrates under ultrahigh vacuum (UHV) conditions. Investigation of the resulting deposited clusters was performed by infrared reflection absorption spectroscopy (IRAS) and thermal desorption spectroscopy (TDS). The IR frequencies of the soft-landed VBz(2) clusters show excellent agreement with the fundamentals reported in IR data of VBz(2) in an argon matrix. The analysis of IRAS spectra reveals that while there was no orientational preference of the VBz(2) clusters on a bare gold substrate, the VBz(2) clusters deposited onto the SAM substrates were highly oriented with the molecular axis 70-80 degrees tilted off the surface normal. In addition, analysis of TDS spectra revealed unusually large adsorption heats of the physisorbed VBz(2) clusters. The present results are explained by cluster penetration into the long-chain alkanethiolate SAM and for the first time demonstrate the matrix isolation of gas-phase organometallic clusters around room temperature.     

Construction of Chiral Tri‐ and Tetra‐Arylmethanes Bearing Quaternary Carbon Centers: Copper‐Catalyzed Enantioselective Propargylation of Indoles with Propargylic Esters

Copper‐catalyzed enantioselective propargylation of indoles with propargylic esters and sequential Huisgen cycloaddition with azides lead to the construction of chiral triarylmethanes, bearing a quaternary carbon center, with high to excellent enantioselectivities. The result described herein can be used in the enantioselective preparation of a tetraarylmethane.