NMR investigation of the solubility of some lubricants in rigid and in impact modified PVC

The solubility behaviour of two paraffin-waxes and two monoglyceride-esters normally used as lubricants in PVC-formulations have been studied with wide-line NMR for rigid and for impact modified PVC. It has been shown that the investigated lubricants have limited solubility in PVC. In the impact modified product, the monoglyceride-esters are partly dissolved in the elastomer phase and partly in the PVC-phase. The paraffin-waxes have limited solubility in the elastomer and in the PVC-phases, and a considerable amount forms a separate phase.     

Twofold discretization and reconstruction of an infinite radiation field

Discretization method for unfolding Fredholm equation of the first kind is suggested for the reconstruction of an infinite monoenergetic radiation field scanned by a directional detector. The method is readily applicable for scanning carried out in planes with constant radial angles.     

Synthesis and some properties of gem-dichlorocyclopropane carboxaldehyde acetals and cyclopropane carboxaldehyde acetals

α,β-Unsaturated aldehyde acetals add :CCl₂ (obtained in accordance with Makosza procedure) to form gem-dichlorocyclopropanecarboxaldehyde acetals (1) in high yields when the ratio of reactants is no less than 1:4. The addition of :CCl₂ to polyunsaturated aldehyde acetals in the above conditions proceeds regioselectively at double bonds enriched by electrons. Compounds 1 are reduced by sodium in liquid ammonia to give cyclopropanecarboxaldehyde acetals (2). Both 1 and 2 are hydrolized by dilute H₃P0₄ to the corresponding aldehydes and are added to vinyl ethers in the presence of BF₃·Et₂O to produce only 1:1 adducts which are hydrolyzed by a mixture of AcOH-AcONa-H₂O to give β-formylcyclopropanes which were previously unknown.     

Untersuchungen an einigen Einkristallen des Systems CuxHg1–xCr2Se4

Study of Some Single Crystals of the Cu_xHg_1–xCr₂Se₄ System Single crystals of the Cu_xHg_1–xCr₂Se₄ for 0 ≤ x ≤ 0.077 were prepared by the chemical transport method. The crystals were analyzed and investigated by X-rays. Some electric and magnetic properties of the single crystals were determined and the results obtained are discussed.     

Marine adhesives. IV: Hexosamine content of Balanus eburneus adhesive

The adhesive secreted by the barnacle, Balanus eburneus, has been demonstrated to contain two hexosamines, glucosamine and galactosamine. Degradation of the hexosamines during hydrolysis of the adhesive appears to be the reason why previous studies of the adhesive have indicated the absence of hexosamines, or the presence of only one hexosamine.     

Polarographic reduction of pyridinium ion in pyridine tetraethylammonium perchlorate as background electrolyte

Tetraethylammonium perchlorate, compared to lithium perchlorate as background electrolyte for the reduction of pyridinium ion in pyridine, is effective over a wider potential range, but is more difficult to obtain in a pure state; slight amounts of impurities do not, however, affect the pyridinium wave. The pyridinium wave produced in 0.1 M Et₄NClO₄ may occur at a more negative potential than the main pyridinium wave in 0.1 M LiClO₄, depending on the source of the pyridinium ion, but still appears to be due to a diffusion-controlled reduction, whose limiting current is linearly proportional to concentration; the prewave observed in LiCl0₄ background generally does not appear in Et₄NClO₄ background. Specific differences in the effect of Li(I), Na(I) and Et₄N(I) background cation appear to be due to electrocapillary phenomena and perhaps to the extent of solvation of the ions. The constancy of current for solutions containing acetic acid with added acetate, pyridinium nitrate with added nitrate, and benzoic acid with added benzoate indicate that the pyridinium reduction is independent of anion concentration.     

Application of the rotated dropping mercury electrode to the analysis of mixtures of electroactive substances

The use of poylacrylamide is recommended instead of gelatin as an ideal maximum suppressor to be employed with both the rotated dropping mercury electrode (RODE) and conventional dropping electrode (DME). It is retained at the mercury surface over the entire potential range and does not combine with heavy metals. Reproducibility of the measurement of the residual current and that of the limiting current at the RDME were studied, and it was found that accurate determinations of a single constituent (±2%) are possible at concentrations as low as 1 to 2.10^-5M. The variation of the limiting current with potential is much greater at the RDME than at the DME. This effect must be considered in the analysis of a mixture of electroactive species at the RDME. Method have been discussed for making the proper correction for a preceding wave when a limiting current of a mixture of constituents is measured. Because of its high sensitivity and good reproducibility of results, the RDME is recommended for the analysis of solutions containing one or more electroactive species at concentrations less than 10^-4M.