Comparative Electrochemical and Spectroscopic Studies of I‐Motif‐forming DNA Nonamers

The paper shows the structural diversity of cytosine (C)‐rich oligodeoxynucleotides (ODNs) arising from their detail nucleotide sequence and experimental conditions. In slightly acidic solutions, the ODN nonamers with different adenine (A) and cytosine (C) sequences can adopt non‐canonical structures involving protonated bases. A distinct secondary structure formed in (C)‐rich sequences, called i‐motif (iM), consists of hemiprotonated and intercalated cytosine base pairs (C.C⁺). Folding and unfolding of particular structures in solutions were monitored by ¹H NMR and CD spectroscopies and native polyacrylamide gel electrophoresis (PAGE), which are capable to determine their structural characteristics. Effects of sequences and their proclivity to formation of the iM on electrochemical behaviour of the ODN nonamers were studied by electrochemical methods. The LSV signals of A and C obtained from the reductive dissolution of ODN adsorption layers on a hanging mercury drop electrode were processed by elimination voltammetry with linear scan (EVLS), which revealed complex effects of the nonamer properties (namely their primary and secondary structure confirmed in solution) on their adsorption and reduction activity.     

Experimental investigations on steady wake effects in a high-lift turbine cascade

This paper reports on the investigation of steady wake effects in cascades. An annular cascade rig, where two stators having the same blade pitch can be circumferentially traversed relatively to each other, is used to analyse the profile losses and the boundary layer development of the downstream stator for different circumferential positions of the upstream stator (clocking positions). Different measurement techniques are used such as three-hole pressure probes, and hot wire- and surface-mounted hot-film probes. The results show a varying pressure loss coefficient of the downstream cascade (S2) for different clocking positions of the upstream cascade (S1_SP).     

Polymerization of lactams—IX. Thermal degradation of anionic polymerizates of 6-caprolactam—changes of the number of polymer molecules at the initial stage of the process

When heating anionic polymerizates of 6-caprolactam, the polymerization degree of the product decreases. The instantaneous rate of the process depends on the concentration of catalytic components, temperature, and heating time. Initially, the process occurs as a consequence of splitting amide-bonds through disproportionation reactions induced by the presence of strong base. However, the whole course of the process is also governed by condensation reactions of the growth centres where the base is consumed. There is a relationship between the time at 250° and number of polymer molecules. The relationship corresponds to experimental data for the concentration range of catalytic components of interest (lithio-caprolactam) and for initiator-activator ratios between 0·5 and 3

$\text{d}{}^2\text{n}\text{d}\text{t}{}^2\text{+}\text{const.}\text{d}\text{n}\text{d}\text{t}\text{=0.}$

This relationship was employed to determine relations between the rate of forming new polymer molecules and that of decay of the strong base.     

On the convergence and divergence of Bairstow's method

Summary Necessary and sufficient condition of algebraic character is given for the invertibility of the Jacobian matrix in Bairstow's method. This leads to a sufficient condition for local quadratic convergence. Results also yield the rank of the Jacobian, when it is singular. In the second part of the paper we give several examples for two step cyclization and more complicated kind of divergence. Some of the polynomials in divergence examples are proved to be irreducible over the field of rational numbers.     

Tricyclic orthoamides: Effects of lone-pair orientation upon NMR spectra

A series of novel tricyclic orthoamides has been synthesized. The stereochemical dependence of methine ¹H chemical shifts and ^IJ_CH are reported.     

Density perturbations excited near a pulsating point source in a streaming plasma

The leading term of the electron density perturbations around a harmonic point source moving with a superthermal velocity through a maxwellian plasma is studied for distances that tend to zero. Pronounced asymmetry is found, the field being concentrated mainly in a conical region downstream behind the source (the Cherenkov cone).     

Über das Dreistoffsystem Na2S-Sb2S3-H2O. II

Zusammenfassung Das System Na₂S–Sb₂S₃–H₂O wurde bei 20° untersucht. Folgende Bodenkörper treten dabei auf: Na₂S·9 H₂O (A), Na₃SbS₃·8 H₂O (B), NaSbS₂ (C und C'), Na₂Sb₄S₇·2 H₂O (D) und Sb₂S₃ (E).D bildet in Nachbarschaft gegen C eineMischphase, die sich durch stark gekrümmte, faserartig aufgebaute Kristalle auszeichnet.Mit 8 Abbildungen.I. Mittlg. siehe vorangehende Arbeit.Auszug aus der Dissertation vonR. Fiala, Universität Wien (1949).     

Synthesis of oxazolo[4,5-c]quinolones by thermolytic degradation of 4-azido-2(1H)-quinolones

4-Azido-2(1H)-quinolones 1 are thermolyzed in the presence of carboxylic acids and polyphosphoric acid to yield oxazolo[4,5-c]quinolones 3. Formation of other possible isomeric ring closure products such as oxazolo[5,4-c]quinolones 2 or isoxazolo[4,3-c]quinolones 4 could be excluded by independent syntheses.