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Katalytische Umwandlung von "Flur-Chlor-Kohlenwasserstoffen" zu umweltverträglichen Verbindungen
(2002)
In the CPMAS spectra of soil samples, the paramagnetic soil constituents partially discriminate against the Signal intensity of the 13C atoms.The aim of the study was to check to what extend the signal depression is selective to a certain kind of carbon species. A strong linear correlation between the detectability of carbon and the cube root of wt.% Fe was observed for both, the total signal and the signal of the carbon species as well. For a C:Fe ratio of 1,5 - 20 non selective signal loss caused by the iron particles dominates. Despite the high percentage of non-detectable carbon the 13C CPMAS spectra correctly reflect the relative composition of soil organic matter
Thermal properties of block copolymer, poly(N-isopropyl acrylamide)-block-poly(3-[N-(3-methacrylamido-propyl)- N,N-dimethyl]-ammonio propane sulfonate), PNIPA-b-PSPP have been studied in pure and saline (NaCl) aqueous solutions by dynamic laser light scattering (DLS). The copolymer [Mw(PNIPA) 10800 g/mol and Mw(PSPP) 9700 g/mol] exhibits both an upper (UCST 9 oC) and lower (LCST 32 oC) critical solution temperatures in pure water. The addition of NaCl enhances the solubility of the zwitterionic polymer, PSPP, leading to the disappearance of the UCST. On the other hand, the solubility of PNIPA in water decreases as NaCl is added. At 20 oC the copolymer shows a bimodal size distribution through the NaCl concentration range of 0-0.93 M above a certain limiting polymer concentration. The slow and fast components of the diffusion coefficients of the polymer have been calculated. A gradual addition of salt turns the mutual interactions from zwitterionic attractions between PSPP blocks to hydrophobic attractions between PNIPA blocks. The formation of the aggregates and the aggregate sizes at T < UCST and T > LCST are influenced by polymer and salt concentrations. Below UCST the aggregates in saline polymer solutions are larger than those in pure polymer solutions. Above LCST the aggregate size is determined by the salt concentration.