The preparation of carboxylated hyperbranched polyglycerols of narrow polydispersity was achieved by modification (78-90%) of the hydroxyl end groups via Michael addition of acrylonitrile, followed by hydrolysis. High conversion could only be achieved for low molecular weight starting materials (520 and 1,030 g mol-1). The solution properties of the resulting materials were investigated by dyna...

addition of methyl oleate (1%) to the original fermentation culture increased the antibiotic titer3). Under these conditions, three nigericin-type antibiotics were isolated, grisorixin (1) (unpublished data), abierixin3) and epinigericin4) (3). The comparative biological activity of the two epimeric antibiotics, nigericin and epinigericin on a protist Tetrahymena pyriformis GL5) and Bacillus ce...

This research focuses on the synthesis and characterization of a piezoelectric (β-CN)APB/ODPA polyimide. The remanent polarization and piezoelectric d31 and g33 coefficients are reported to assess the effect of synthesis variations. Each of the materials exhibits a level of piezoelectricity which increases with temperature. The remanent polarization is retained at temperatures close to the glas...

The effect of the amount of pore generating agent (polyvinylpyrrolidone) added to standard polymer membranes containing 18 wt.% of polyethersulfone on the physicochemical properties of the membranes and their capacity for removal of iron and copper ions from the liquid phase was studied. The membranes were obtained by the phase inversion method. The results have shown that the modification of p...

A simple theoretical model of liquid crystal ͑LC͒ alignment by exposure to linearly polarized ultraviolet ͑UV͒ light is proposed. The model predicts a universal relationship describing the change of the LC anchoring direction with exposure times, and the changes of polarization direction for the case of a double linearly polarized UV exposure process. This relationship is quantitatively confirmed b...