TY - JOUR A1 - Lutz, J.-F. A1 - Pfeifer, S. A1 - Chanana, M. A1 - Thünemann, Andreas A1 - Bienert, Ralf T1 - H-Bonding-Directed Self-Assembly of Synthetic Copolymers Containing Nucleobases: Organization and Colloidal Fusion in a Noncompetitive Solvent N2 - The self-organization of random copolymers composed of a nucleobase monomer (either 1-(4-vinylbenzyl)thymine or 9-(4-vinylbenzyl)adenine) and dodecyl methacrylate (DMA) was studied in dilute chloroform solutions. The balance between the molar fractions of the nucleobase monomer (leading to intermolecular H-bonding) and DMA (soluble moiety in chloroform) in the polymer chains was found to be the parameter that principally influences the self-organization. DMA-rich copolymers are molecularly soluble in chloroform, whereas nucleobase-rich copolymers are insoluble in this solvent. Copolymers possessing an equimolar comonomer composition self-assemble into micrometer-sized particles physically cross-linked by intermolecular H-bonds (either thymine-thymine or adenine-adenine interactions, depending on the studied copolymer). Nevertheless, when mixed together, thymine- and adenine-based colloids fuse into thermodynamically stable microspheres cross linked by adenine-thymine interactions. KW - Synthetic polymers KW - Self-organization KW - H-bonding KW - Nucleobases KW - Confocal fluorescence microscopy PY - 2006 U6 - https://doi.org/10.1021/la061382a SN - 0743-7463 SN - 1520-5827 VL - 22 IS - 17 SP - 7411 EP - 7415 PB - American Chemical Society CY - Washington, DC AN - OPUS4-12637 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wiedensohler, A. A1 - Wiesner, A. A1 - Weinhold, K. A1 - Birmili, W. A1 - Herrmann, M. A1 - Merkel, M. A1 - Müller, T. A1 - Pfeifer, S. A1 - Schmidt, A. A1 - Tuch, T. A1 - Velarde, F. A1 - Quincey, P. A1 - Seeger, Stefan A1 - Nowak, A. T1 - Mobility particle size spectrometers: Calibration procedures and measurement uncertainties N2 - Mobility particle size spectrometers (MPSS) belong to the essential instruments in aerosol science that determine the particle number size distribution (PNSD)in the submicrometer size range. Following calibration procedures and target uncertainties against standards and reference instruments are suggested for a complete MPSS quality assurance program: a) calibration of the CPC counting efficiency curve (within 5% for the plateau counting efficiency; within 1 nm for the 50% detection efficiency diameter), b) sizing calibration of the MPSS, using a certified polystyrene latex (PSL) particle size standard at 203 nm (within 3%), c) intercomparison of the PNSD of the MPSS (within 10% and 20% of the dN/dlogDP concentration for the particle size range 20 – 200 nm and 200 to 800 nm, respectively), and d) intercomparison of the integral PNC of the MPSS (within 10%). Furthermore, following measurement uncertainties have been investigated: a) PSL particle size standards in the range from 100-500nm match within 1% after sizing calibration at 203 nm. b) Bipolar diffusion chargers based on the radioactive nuclides Kr85, Am241 and Ni63 and a new ionizer based on corona discharge follow the recommended bipolar charge distribution, while soft X-ray-based charges may alter faster than expected. c) The use of a positive high voltage supply show a 10% better performance than a negative one. d) The intercomparison of the integral PNC of an MPSS against the total number concentration is still within the target uncertainty at an ambient pressure of approximately 500 hPa. KW - Measurement uncertainties KW - Mobility particle size spectrometer (MPPS) KW - Condensation particle counter (CPC) KW - Calibration PY - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-425060 SN - 1521-7388 VL - 52 IS - 2 SP - 146 EP - 164 PB - Tailor & Francis CY - USA AN - OPUS4-42506 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -