Aqueous solution behavior of comb‐shaped poly(2‐ethyl‐2‐oxazoline)

A series of comb polymers consisting of a methacrylate backbone and poly(2‐ethyl‐2‐oxazoline) (PEtOx) side chains was synthesized by a combination of cationic ring‐opening polymerization and reversible addition–fragmentation chain transfer polymerization. Small‐angle neutron scattering (SANS) studies revealed a transition from an ellipsoidal to a cylindrical conformation in D₂O around a backbone degree of polymerization of 30. Comb‐shaped PEtOx has lowered T_g values but a similar elution behavior in liquid chromatography under critical conditions in comparison to its linear analog was observed. The lower critical solution temperature behavior of the polymers was investigated by turbidimetry, dynamic light scattering, transmission electron microscopy, and SANS revealing decreasing T_cp in aqueous solution with increasing molar mass, the presence of very few aggregated structures below T_cp, a contraction of the macromolecules at temperatures 5 °C above T_cp but no severe conformational change of the cylindrical structure. In addition, the phase diagram including cloud point and coexistence curve was developed showing an LCST of 75 °C of the binary mixture poly[oligo(2‐ethyl‐2‐oxazoline)methacrylate]/water. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Granting and managing loans for micro-entrepreneurs: New developments and practical experiences

We present a methodology to grant and follow-up credits for micro-entrepreneurs. This segment of grantees is very relevant for many economies, especially in developing countries, but shows a behavior different to that of classical consumers where established credit scoring systems exist. Parts of our methodology follow a proven procedure we have applied successfully in several credit scoring projects. Other parts, such as cut-off point construction and model follow-up, however, had to be developed and constitute original contributions of the present paper. The results from two credit scoring projects we developed in Chile, one for a private bank and one for a governmental credit granting institution, provide interesting insights into micro-entrepreneurs’ repayment behavior which could also be interesting for the respective segment in countries with similar characteristics.     

Ein schnelles ma?analytisches Verfahren zur Bestimmung von Quecksilber

Ohne Zusammenfassung     

GaAsN-on-GaAs MBE using a DC plasma source

A new dc plasma source for MBE growth of GaAsN layers is suggested. The efficiency of nitrogen incorporation, crystal perfection, surface morphology, and luminescent properties of the epilayers vs. operation conditions of the source are studied.