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This analytical study models features of the interaction of flow distortions, such as gusts and wakes, with blade rows of advance-type fans and compressors having high-tip Mach numbers. A typical distortion is assumed to have harmonic time dependence and is described, at a far upstream location, in three orthogonal spatial coordinates by a double Fourier series. It is convected at supersonic velocity relative to a linear cascade described as an unrolled annulus. Conditions are selected so that the component of this velocity parallel to the axis of the turbomachine is subsonic, permitting interaction between blades through the upstream as well as downstream flow media. A strong, nearly normal shock is considered in the blade passages which is allowed curvature and displacement. The flows before and after the shock are linearized relative to uniform mean velocities in their respective regions. Solution of the descriptive equations is by adaptation of the Wiener-Hopf technique. This enables a determination of distortion patterns through and downstream of the cascade, and of pressure distributions on the blade surfaces. Details of interaction of the distortion with the in-passage shock are discussed. Influences of amplitude, wavelength, and phase of the distortion on lifts and moments of cascade configurations are presented. Numerical results are clarified by reference to an especially orderly pattern of upstream vortical motion in relation to the cascade parameters.

The structure of a diterpene with a new bicarbocyclic ring skeleton has been solved by analysis of the 400-MHz 1H n.m.r. spectrum, and confirmed by a single-crystal X-ray analysis.

Th 1H-NMR-spectra of benzene and benzene-1-13C in the isotropic phase (CCl4solution) as well as in the nematic phase of a liquid crystal are analysed and the resulting direct and indirect couplings presented. The comparison of observed direct couplings with values calculated from known Raman structural data shows deviations of up to 9% relative to the HH(orto)-coupling. This corresponds to an apparent increase of the carbon-proton distance of 0.03 A. Possible reasons are discussed such as anisotropy of the indirect couplings, solvent effects on indirect couplings and intramolecular vibrations. The conclusion is reached that the consideration of intramolecular vibrational motion perfectly explains the discrepancies.

Nematic liquids are used as solvents for NMR investigations. By this method a partial orientation of the solute molecules is obtained, causing splittings of the NMR signals by intramolecular direct dipole-dipole interactions. The high resolution spectra of benzene, some derivatives of benzene, and 4-chlorobenzoic acid are reported. As solvents nematic melts of 4.4′-di-n-hexoxy- and 4.4′-di-n-heptoxyazoxybenzene and 4-n-butoxybenzoic acid were used. The linewidth remains small despite the very strong direct dipole-dipole interactions that could be observed in some cases. With benzene and 1.3.5-trichlorobenzene the anisotropy of the screening has been determined. It was found Δσ = σξξ— (σξξ+ σηη)/2 = -2.88 x 10-6for benzene and △σ= -4.91 x 10-6for 1.3.5-trichlorobenzene (ξ-axes normal to molecular plane).

Die direkte und vollständige Analyse komplexer kernmagnetischer Resonanzspektren vom Typ A2B2nach einem früher angegebenen Verfahren wird ausführlich beschrieben.

Résumé: Quelques propriétés de l'eau adsorbée dans la pâte de ciment durcie et dans les trois constituants principaux complètement hydratés du ciment Portland ont été étudiées avec l'analyse thermique différentielle, la thermo-gravimétrie et la résonance magnétique nucléaire. Lorsqu'une éprouvette séchée est réhumidifiée, l'eau adsorbée contribe d'abord à la formation d'une mono-couche. L'eau adsorbée, en tant qu'eau d'hydratation, n'est partiellement liée dans la structure du sel que pour les humidités les plus élevées. Selon les tout premiers résultats fournis par les mesures de la résonance magnétique nucléaire, l'eau adsorbée dans la mono-couche se comporte comme un gaz bi-dimensionnel de Van-der-Waals.

Abstract: A model of the random walk is formulated to allow a simple computing procedure to replace the difficult problem of solution of the Fokker-Planck equation. The step sizes and probabilities of taking steps in the various directions are expressed in terms of Fokker-Planck coefficients. Application is made to many particle systems with Coulomb interactions. The relaxation of a highly peaked velocity distribution of particles to equilibrium conditions is illustrated.

The PMR spectra of carbon-13 and nitrogen-15 substituted acetonitrile have been investigated in 3 different nematic solutions. From the direct magnetic spin-spin interactions values for the H - G - H - bond angle of the methyl group and for the other relative internuclear distances ware calculated under the assumption that the anisotropic part of the indirect spin-spin interactions can be neglected.Small differences in the molecular geometry were observed in the three nematic solvents and also between the latter and the gas phage (microwave data). Approximate nuclear positions can be calculated if the PMR data are combined with microwave data, e.g. the moment of inertia of the molecule in the gas phase. It is shown that the nuclear positions calculated by this method are in approximate agreement with pure microwave data. Under the assumption that acetonitrile is aligned preferentially parallel to the magnetic field, the absolute signs of the indirect spin couplings 1J13C-H 2J13C-C-H and 3J15N-CCH are found to be positive, negative and negative, respectively.

The analysis of the proton magnetic resonance spectra of a 3-protonsystem with C2-symmetry and of a special 4-protonsystem (rotating methylgroup and one interacting proton) is given in terms of the magnetic dipole-dipole couplings and the chemical shifts. The application to the spectrum of 3,5-dichloro-benzoic acid, dissolved in nematic 6-n-hexyloxy-2-naphthoic acid, and to 2,3,5,6- and 2,3,4,6-tetrachloro-anisole and 2,3,5,6-tetrachloro-toluene, dissolved in nematic 4,4-di-n-hexyloxy- or -heptyloxy-azoxybenzene gives information on the molecular orientation and the anisotropy of the chemical shifts. The ratio of the proton-proton distances of the toluene compound is determined.

Durch Protonenresonanz-Untersuchungen wird nachgewiesen, daß es sich bei den durch Dehydrobromierung aus 4.5.6.7-Tetra-brom-benzofuroxan bzw. -benzofurazan entstehenden Di-bromverbindungen nur um das 4.7-Dibrom-benzofuroxan bzw. 4.7-Dibrom-benzofurazan handeln kann.

The hematoporphyrin‐sensitized photoreaction of the aromatic retinoid (I) using light with λ ≥ 400 nm yields the cyclodimers (II) (space group P21/a, Z=4) and (III) (P1, Z=2).