TY - GEN A1 - Müller, Klaus A1 - Richter, Matthias A1 - Philip, Shine A1 - Kunst, Manuel A1 - Schmeißer, Dieter T1 - Excited states in P3HT and P3HT/PCBM blends T2 - BioNanoScience Y1 - 2012 SN - 2191-1630 VL - 2 IS - 1 SP - 42 EP - 51 ER - TY - GEN A1 - Müller, Klaus A1 - Richter, Matthias A1 - Friedrich, Daniel A1 - Paloumpa, Ioanna A1 - Kramm, Ulrike Ingrid A1 - Schmeißer, Dieter T1 - Spectroscopic characterization of Cobalt–Phthalocyanine electrocatalysts for fuel cell applications T2 - Solid State Ionics N2 - For polymer–electrolyte–membrane fuel cells (PEM-FC), platinumcatalysts on carbon based substrates are state of the art, due to high electrochemical activity and chemical stability in acid electrolytes. High costs of platinum force investigations of alternative catalysts. With respect to the oxygen reduction reaction, possible candidates are transition metal (TM) complexes like TM-porphyrines or TM-phthalocyanines. Pyrolysis on carbon based substrates improves the catalytic activity. Highest activities were found for Fe or Co as transition metal centers. We present results of the pyrolysis of Co-phthalocyanine (CoPc) on carbon black. Besides an investigation of morphology by scanning electron microscopy (SEM) and chemical composition by energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) during pyrolysis, we present a near edge X-ray absorption fine structure (NEXAFS) study of the chemical composition for the related annealing steps. This investigation is accompanied by an electrochemical characterization of the catalytic activity and selectivity. The XPS and NEXAFS data indicate a decomposition of the CoN4(chelate-) complex during pyrolysis. The N1s data for 800 °C show graphite-like, formally pyrrolic and pyridinic like features, without any significant contri-bution of Co. The Co2p data for both, XPS and NEXAFS are dominated by CoO/Co2O3. It can be concluded that during the pyrolysis cobalt particles are formed by the disintegration of CoN4-centers, after pyrolysis these par-ticles become oxidized upon contact with air. KW - Co-phthalocyanine KW - Catalysis KW - Oxygen reduction reaction (ORR) KW - XPS KW - NEXAFS Y1 - 2012 U6 - https://doi.org/10.1016/j.ssi.2011.12.013 SN - 1872-7689 IS - 216 SP - 78 EP - 82 ER - TY - GEN A1 - Städter, Matthias A1 - Müller, Klaus A1 - Rachow, Fabian A1 - Richter, Matthias A1 - Schmeißer, Dieter T1 - Ambient pressure thermal desorption spectroscopy (AP-TDS) of NiO/SiO2 catalysts T2 - Environmental Earth Sciences N2 - The Sabatier reaction is a key process in the "power-to-gas" application which is considered to con-tribute to future chemical energy storage systems. In this contribution we focus on the catalytic active sites of a NiO catalyst supported on SiO2(NiO/SiO2) which is commonly used in the Sabatier reaction. A novel technique for the characterization of the active sites is presented and dis-cussed using thermal desorption spectroscopy at ambient pressure. This analytical tool is operated under reaction conditions and allows element specific measurements during the catalytic process of CO2 reforming towards methane. Beside the desorption experiments, XPS and XAS measurements of pristine and catalytically used samples are performed to determine the influence of the Sabatier reaction conditions on the surface structure of the catalyst. KW - CO2 KW - NiO KW - TDS KW - XAS KW - XPS Y1 - 2013 U6 - https://doi.org/10.1007/s12665-013-2835-8 SN - 1866-6280 VL - 70 IS - 8 SP - 3779 EP - 3784 ER - TY - GEN A1 - Rathmann, Katharina A1 - Bilz, Ludwig A1 - Hurrelmann, Klaus A1 - Kiess, Wieland A1 - Richter, Matthias T1 - Is being a “small fish in a big pond” bad for students´ psychosomatic health? A multilevel study on the role of class-level school performance T2 - BMC Public Health N2 - Background. Features of schools and classes are closely related to students´ health and wellbeing. However, class composition (e.g. in terms of school performance) has rarely been examined in relation to students´ health and wellbeing. This study focuses on the so called Big-Fish-Little-Pond-Effect (BFLPE), by investigating whether the level of high-performing students in classroom is negatively associated with psychosomatic complaints of students who perceive themselves as poor performers. Methods. Data were derived from the German sample of the WHO-Collaborative “Health Behaviour in School-aged Children (HBSC)” study 2013/2014. The sample included 5226 11-, 13- and 15-year-old students. Individual perceived school performance (PSP) was included (very good/good vs. average/below average PSP) at the individual student-level. At the class-level, school performance in class was generated by aggregating the share (in percentage) of students who report a very good/good PSP to the class-level, indicating the percentage of students with good/very good PSP in classroom. Using multilevel regression models, the association between class-level school performance (in percentage of students with very good/good PSP) and individual psychosomatic complaints were analyzed, stratified by students´ individual PSP. Results. Students who report average/below average PSP showed higher likelihoods of psychosomatic complaints (Odds Ratio: 1.75; 95% Confidence Interval: 1.52–2.03) compared to counterparts with very good/good PSP. The aggregated class-level PSP was not significantly associated with psychosomatic complaints. However, in line with the BFLPE, results further revealed that students with average/below average PSP, who attend classes with a higher percentage of students who report very good/good PSP, had higher likelihoods of psychosomatic complaints (Odds Ratio: 1.91; 95% Confidence Interval: 1.01–4.01) compared to classmates with very good/good PSP. Conclusions. This study revealed that class composition in terms of PSP was differentially associated with students´ psychosomatic complaints, depending on their individual PSP. Findings highlight the vulnerability of students with poor PSP placed in classes with a higher percentage of students with good PSP. Results of this study therefore indicate a need for initiatives for low performing students from teachers and school staff in class. KW - School performance KW - Reference group effects KW - Health complaints KW - BFLPE KW - Multilevel analysis KW - HBSC Y1 - 2018 U6 - https://doi.org/10.1186/s12889-018-5977-5 SN - 1471-2458 VL - 18 ER - TY - GEN A1 - Rathmann, Katharina A1 - Herke, Max A1 - Bilz, Ludwig A1 - Rimpelä, Arja A1 - Hurrelmann, Klaus A1 - Richter, Matthias T1 - Class-level school performance and life satisfaction: Differential sensitivity for low- and high-performing school-aged children T2 - International Journal of Environmental Research and Public Health N2 - This study investigates whether class-level school performance affects students’ life satisfaction and if there are differential effects for high- and low-performing students. Data were derived from the National Educational Panel Study, including n = 5196 students (49.6% girls), nested in 478 classes and 250 secondary schools. School performance in class was measured by aggregating individual grade point average in Mathematics and German. The study could not reveal the “big-fish-little-pond”-effect regarding students’ life satisfaction but found differential effects for high- vs. low performing students. There was no significant association for low-performing students attending classes with higher class-level performance However, low-performing students revealed the lowest life satisfaction. High-performing students placed in classes with higher average performance reported lower life satisfaction compared to high-performing students in classes with lower average performance. This study provides evidence for the impact of the learning environment in class on school-aged children’s life satisfaction, by highlighting the differential sensitivity of high-performing students when placed in classes with higher or lower average performance. KW - school performance KW - social comparision KW - life satisfaction KW - big-fish-little-pond-effect KW - multilevel analysis KW - National Educational Panel Study Y1 - 2018 U6 - https://doi.org/10.3390/ijerph15122750 SN - 1660-4601 SN - 1661-7827 VL - 15 IS - 12 ER -