Proton NMR investigations of the smectic-C phases of three 4,4'-bis-/?-alkyloxy-azoxybenzenes (C 7 , C 8 , C 9 ) with temperature independent tilt angles are presented.The behaviour of well-aligned samples (strong magnetic field ^ 1.5 T, slow cooling rate) under rotation in the field can be described by the models of Luz and Meiboom, and Wise, Smith, and Doane, (LM/WSD), resp. However, on polarization of the samples in presence of magnetic fields ^ 0.75 T the molecular directors are not arranged preferentially parallel to the direction of the polarizing magnetic field but are rather inclined, i.e., the layers are stacked preferentially perpendicular to the original magnetic field direction (PSL model). It is shown that all the angular dependences of NMR second moments can be interpreted in terms of a superposition of the LM/WSD and PSL models, or, on the other hand, by assuming totally disordered fractions of the samples together with portions that fully obey the behaviour demanded by one of the above models (LM/WSD or PSL). The tilt angles derived from the comparison of experimental and theoretical angular dependences of the second moments for well-aligned samples are applied to the explanation of the experiments at lower polarizing fields successfully, too.

The density issue is a nonissue if comparable numbers of hair are transplanted per square centimeter.

No abstract

The results of our data demonstrate cutaneous micrographic surgery to be an excellent modality to address this locally aggressive tumor. Cutaneous micrographic surgery is an advantageous therapy for this tumor because of its meticulous tissue removal, tissue mapping, and tissue sparing qualities.

Dedicated t o Professor Herrnann NEELS on the occasion of his 70th birthdayWe present proton NMR second inornents studies of some compounds exhibiting sniectic-C phases. From the comparison of experimental and theoretical angular dependences of the second moments the tilt angles S are derived. The ratio f of the second moments of saniples with statistical distribution of domain orientations and of perfectly aligned samples is calculated and compared with experiinental data. For certain substances with constant tilt here are significant deviations from the theoretically expected values suggesting that the underlying theoretical model has still t o be modified. Es werden Untersuchungen des zweiten Moments der Protonen-NMR-Spektren von Substanzen vorgestellt, die srnektische C-Phasen ausbilden. Aus dern Vergleich von experimentellen und berechneten Winkelabhangiglreiten der zweiten Moniente werdenTiltwinkel 6 abgeleitet. Das Verhaltnis f der zweiten Momente von Proben mit statistischer Verteilung der Domanenorientierungen und von vollstiindig ausgerichteten Proben wird berechnet und mit experimentellen Daten verglichen. Fur bestimmte Substanzen init. konstantem Tilt zeigen sich signifikante Abweichungen von den theoretisch zu erwartenden Werten, was darauf hinweist, daI3 das ziigrunde liegende theoretische Model1 modifiziert werden sollte.