Acid-Catalyzed RNA-Oligomerization from 3’,5’-cGMP

The assembly of ancient informational polymers from nucleotide precursors is the central challenge of life's origin on our planet. Among the possible solutions, dry polymerization of 3’,5’-cyclic guanosine monophosphate (3’,5’-cGMP) has been proposed as a candidate to create oligonucleotides of 15–20 units in length. However, the reported sensitivity of the reaction to the presence of cations raised questions of whether this chemistry could be relevant in a geological context. The experiments in this study show that the presence of cations is not restrictive as long as the reaction is conducted in an acidic environment, in contrast to previous reports that suggested optimal conditions at pH 9.     

A model of structure periodically modulated in three dimensions

A model of structure periodically modulated in three dimensions is calculated in the presented paper and applied to the alloy Cu₈₀Au₂₀. The existence and intensity of the side-bands of the Bragg lines appearing with hyperstructural lines on films of this alloy after heating to temperature on the border of the order-disorder transformation are explained by means of the given model and the value of the period of sinusoidal variation of the lattice parameter and scattering power is calculated.ikova 22, Brno, Czechoslovakia.The author thanks Mrs. V. Gregor and Mr. M. Jelínek who prepared the necessary pictures.     

The susceptibility of lead telluride PbTe

The results are given of measuring the temperature dependence of the susceptibility of samples of n- and p-type PbTe, containing either an excess of one or other of the components or ions Cl^–, or Ag⁺, as impurities. The conception of cation or anion vacancies, which can be occupied by a hole or electron, Ag⁺ or Cl^– ions, was employed, in addition to the constants taken from other measurements, to explain the dependences measured.