@article{MullowneyDuncanElsayedetal.2023, author = {Mullowney, Michael W. and Duncan, Katherine R. and Elsayed, Somayah S. and Garg, Neha and van der Hooft, Justin J. J. and Martin, Nathaniel I. and Meijer, David and Terlouw, Barbara R. and Biermann, Friederike and Blin, Kai and Durairaj, Janani and Gorostiola Gonz{\´a}lez, Marina and Helfrich, Eric J. N. and Huber, Florian and Leopold-Messer, Stefan and Rajan, Kohulan and de Rond, Tristan and van Santen, Jeffrey A. and Sorokina, Maria and Balunas, Marcy J. and Beniddir, Mehdi A. and van Bergeijk, Doris A. and Carroll, Laura M. and Clark, Chase M. and Clevert, Djork-Arn{\´e} and Dejong, Chris A. and Du, Chao and Ferrinho, Scarlet and Grisoni, Francesca and Hofstetter, Albert and Jespers, Willem and Kalinina, Olga V. and Kautsar, Satria A. and Kim, Hyunwoo and Leao, Tiago F. and Masschelein, Joleen and Rees, Evan R. and Reher, Raphael and Reker, Daniel and Schwaller, Philippe and Segler, Marwin and Skinnider, Michael A. and Walker, Allison S. and Willighagen, Egon L. and Zdrazil, Barbara and Ziemert, Nadine and Goss, Rebecca J. M. and Guyomard, Pierre and Volkamer, Andrea and Gerwick, William H. and Kim, Hyun Uk and M{\"u}ller, Rolf and van Wezel, Gilles P. and van Westen, Gerard J. P. and Hirsch, Anna K. H. and Linington, Roger G. and Robinson, Serina L. and Medema, Marnix H.}, title = {Artificial intelligence for natural product drug discovery}, series = {Nature Reviews Drug Discovery}, volume = {22}, journal = {Nature Reviews Drug Discovery}, number = {11}, publisher = {Springer Nature}, issn = {1474-1776}, doi = {10.1038/s41573-023-00774-7}, pages = {895 -- 916}, year = {2023}, subject = {Maschinelles Lernen}, language = {en} } @article{SchornVerhoevenRidderetal.2021, author = {Schorn, Michelle A. and Verhoeven, Stefan and Ridder, Lars and Huber, Florian and Acharya, Deepa D. and Aksenov, Alexander A. and Aleti, Gajender and Moghaddam, Jamshid Amiri and Aron, Allegra T. and Aziz, Saefuddin and Bauermeister, Anelize and Bauman, Katherine D. and Baunach, Martin and Beemelmanns, Christine and Beman, J. Michael and Berlanga-Clavero, Mar{\´i}a Victoria and Blacutt, Alex A. and Bode, Helge B. and Boullie, Anne and Brejnrod, Asker and Bugni, Tim S. and Calteau, Alexandra and Cao, Liu and Carri{\´o}n, V{\´i}ctor J. and Castelo-Branco, Raquel and Chanana, Shaurya and Chase, Alexander B. and Chevrette, Marc G. and Costa-Lotufo, Leticia V. and Crawford, Jason M. and Currie, Cameron R. and Cuypers, Bart and Dang, Tam and de Rond, Tristan and Demko, Alyssa M. and Dittmann, Elke and Du, Chao and Drozd, Christopher and Dujardin, Jean-Claude and Dutton, Rachel J. and Edlund, Anna and Fewer, David P. and Garg, Neha and Gauglitz, Julia M. and Gentry, Emily C. and Gerwick, Lena and Glukhov, Evgenia and Gross, Harald and Gugger, Muriel and Guill{\´e}n Matus, Dulce G. and Helfrich, Eric J. N. and Hempel, Benjamin-Florian and Hur, Jae-Seoun and Iorio, Marianna and Jensen, Paul R. and Kang, Kyo Bin and Kaysser, Leonard and Kelleher, Neil L. and Kim, Chung Sub and Kim, Ki Hyun and Koester, Irina and K{\"o}nig, Gabriele M. and Leao, Tiago and Lee, Seoung Rak and Lee, Yi-Yuan and Li, Xuanji and Little, Jessica C. and Maloney, Katherine N. and M{\"a}nnle, Daniel and Martin H, Christian and McAvoy, Andrew C. and Metcalf, Willam W. and Mohimani, Hosein and Molina-Santiago, Carlos and Moore, Bradley S. and Mullowney, Michael W. and Muskat, Mitchell and Nothias, Louis-F{\´e}lix and O'Neill, Ellis C. and Parkinson, Elizabeth I. and Petras, Daniel and Piel, J{\"o}rn and Pierce, Emily C. and Pires, Karine and Reher, Raphael and Romero, Diego and Roper, M. Caroline and Rust, Michael and Saad, Hamada and Saenz, Carmen and Sanchez, Laura M. and S{\o}rensen, S{\o}ren Johannes and Sosio, Margherita and S{\"u}ssmuth, Roderich D. and Sweeney, Douglas and Tahlan, Kapil and Thomson, Regan J. and Tobias, Nicholas J. and Trindade-Silva, Amaro E. and van Wezel, Gilles P. and Wang, Mingxun and Weldon, Kelly C. and Zhang, Fan and Ziemert, Nadine and Duncan, Katherine R. and Cr{\"u}semann, Max and Rogers, Simon and Dorrestein, Pieter C. and Medema, Marnix H. and van der Hooft, Justin J. J.}, title = {A community resource for paired genomic and metabolomic data mining}, series = {Nature Chemical Biology}, volume = {17}, journal = {Nature Chemical Biology}, number = {4}, publisher = {Nature}, issn = {1552-4469}, doi = {10.1038/s41589-020-00724-z}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-34708}, pages = {363 -- 368}, year = {2021}, language = {en} } @article{GeneralPoehlerSihleretal.2014, author = {General, S. and P{\"o}hler, D. and Sihler, H. and Bobrowski, N. and Frieß, U. and Zielcke, J. and Horbanski, M. and Shepson, P. B. and Stirm, B. H. and Simpson, W. R. and Weber, Konradin and Fischer, C. and Platt, U.}, title = {The Heidelberg Airborne Imaging DOAS Instrument (HAIDI) - a novel imaging DOAS device for 2-D and 3-D imaging of trace gases and aerosols}, series = {Atmospheric Measurement Techniques}, volume = {7}, journal = {Atmospheric Measurement Techniques}, number = {10}, publisher = {Copernicus}, issn = {1867-8548}, doi = {10.5194/amt-7-3459-2014}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-50179}, pages = {3459 -- 3485}, year = {2014}, abstract = {Abstract. Many relevant processes in tropospheric chemistry take place on rather small scales (e.g., tens to hundreds of meters) but often influence areas of several square kilometer. Thus, measurements of the involved trace gases with high spatial resolution are of great scientific interest. In order to identify individual sources and sinks and ultimately to improve chemical transport models, we developed a new airborne instrument, which is based on the well established Differential Optical Absorption Spectroscopy (DOAS) method. The Heidelberg Airborne Imaging DOAS Instrument (HAIDI) is a passive imaging DOAS spectrometer, which is capable of recording horizontal and vertical trace gas distributions with a resolution of better than 100 m. Observable species include NO2, HCHO, C2H2O2, H2O, O3, O4, SO2, IO, OClO and BrO. Here we give a technical description of the instrument including its custom-built spectrographs and CCD detectors. Also first results from measurements with the new instrument are presented. These comprise spatial resolved SO2 and BrO in volcanic plumes, mapped at Mt. Etna (Sicily, Italy), NO2 emissions in the metropolitan area of Indianapolis (Indiana, USA) as well as BrO and NO2 distributions measured during arctic springtime in context of the BRomine, Ozone, and Mercury EXperiment (BROMEX) campaign, which was performed 2012 in Barrow (Alaska, USA).}, language = {en} } @article{VansteenkisteDeBaerdemaekerChouetal.2008, author = {Vansteenkiste, A. and De Baerdemaeker, J. and Chou, Kang Wei and Stoll, H. and Curcic, Michael and Tyliszczak, T. and Woltersdorf, G. and Back, Christian H. and Sch{\"u}tz, G. and Van Waeyenberge, B.}, title = {Influence of domain wall pinning on the dynamic behavior of magnetic vortex structures: Time-resolved scanning x-ray transmission microscopy in NiFe thin film structures}, series = {Physical Review B}, volume = {77}, journal = {Physical Review B}, number = {14}, publisher = {American Physical Society}, issn = {1098-0121}, doi = {10.1103/PhysRevB.77.144420}, year = {2008}, language = {en} } @article{VansteenkisteChouWeigandetal.2009, author = {Vansteenkiste, A. and Chou, Kang Wei and Weigand, M. and Curcic, Michael and Sackmann, V. and Stoll, H. and Tyliszczak, T. and Woltersdorf, G. and Back, Christian H. and Sch{\"u}tz, G. and Van Waeyenberge, B.}, title = {X-ray imaging of the dynamic magnetic vortex core deformation}, series = {Nature Physics}, volume = {5}, journal = {Nature Physics}, number = {5}, publisher = {Nature Publishing Group}, issn = {1745-2473}, doi = {10.1038/nphys1231}, pages = {332 -- 334}, year = {2009}, language = {en} } @article{EmanuelssonHallquistKristensenetal.2013, author = {Emanuelsson, E. U. and Hallquist, M. and Kristensen, K. and Glasius, M. and Bohn, Birger and Fuchs, H. and Kammer, B. and Kiendler-Scharr, A. and Nehr, Sascha and Rubach, F. and Tillmann, R. and Wahner, A. and Wu, H.-C. and Mentel, Th. F.}, title = {Formation of anthropogenic secondary organic aerosol (SOA) and its influence on biogenic SOA properties}, series = {Atmospheric Chemistry and Physics}, volume = {13}, journal = {Atmospheric Chemistry and Physics}, number = {5}, publisher = {Copernicus}, issn = {1680-7324}, doi = {10.5194/acp-13-2837-2013}, pages = {2837 -- 2855}, year = {2013}, abstract = {Abstract. Secondary organic aerosol (SOA) formation from mixed anthropogenic and biogenic precursors has been studied exposing reaction mixtures to natural sunlight in the SAPHIR chamber in J{\"u}lich, Germany. In this study aromatic compounds served as examples of anthropogenic volatile organic compound (VOC) and a mixture of α-pinene and limonene as an example for biogenic VOC. Several experiments with exclusively aromatic precursors were performed to establish a relationship between yield and organic aerosol mass loading for the atmospheric relevant range of aerosol loads of 0.01 to 10 μg m-3. The yields (0.5 to 9\%) were comparable to previous data and further used for the detailed evaluation of the mixed biogenic and anthropogenic experiments. For the mixed experiments a number of different oxidation schemes were addressed. The reactivity, the sequence of addition, and the amount of the precursors influenced the SOA properties. Monoterpene oxidation products, including carboxylic acids and dimer esters were identified in the aged aerosol at levels comparable to ambient air. OH radicals were measured by Laser Induced Fluorescence, which allowed for establishing relations of aerosol properties and composition to the experimental OH dose. Furthermore, the OH measurements in combination with the derived yields for aromatic SOA enabled application of a simplified model to calculate the chemical turnover of the aromatic precursor and corresponding anthropogenic contribution to the mixed aerosol. The estimated anthropogenic contributions were ranging from small (\&amp;approx;8\%) up to significant fraction (50\%) providing a suitable range to study the effect of aerosol composition on the aerosol volatility (volume fraction remaining (VFR) at 343 K: 0.86-0.94). The aromatic aerosol had higher oxygen to carbon ratio O/C and was less volatile than the biogenic fraction. However, in order to produce significant amount of aromatic SOA the reaction mixtures needed a higher OH dose that also increased O/C and provided a less volatile aerosol. The SOA yields, O/C, and f44 (the mass fraction of CO2+ ions in the mass spectra which can be considered as a measure of carboxylic groups) in the mixed photo-chemical experiments could be described as linear combinations of the corresponding properties of the pure systems. For VFR there was in addition an enhancement effect, making the mixed aerosol significantly less volatile than what could be predicted from the pure systems. A strong positive correlation was found between changes in volatility and O/C with the exception during dark hours where the SOA volatility decreased while O/C did not change significantly. Thus, this change in volatility under dark conditions as well as the anthropogenic enhancement is due to chemical or morphological changes not affecting O/C.}, language = {en} } @article{LuRohrerHollandetal.2012, author = {Lu, K. D. and Rohrer, F. and Holland, F. and Fuchs, H. and Bohn, Birger and Brauers, Theo and Chang, C. C. and H{\"a}seler, R. and Hu, M. and Kita, K. and Kondo, Y. and Li, X. and Lou, S. R. and Nehr, Sascha and Shao, M. and Zeng, L. M. and Wahner, A. and Zhang, Y. H. and Hofzumahaus, A.}, title = {Observation and modelling of OH and HO2 concentrations in the Pearl River Delta 2006: a missing OH source in a VOC rich atmosphere}, series = {Atmospheric Chemistry and Physics}, volume = {12}, journal = {Atmospheric Chemistry and Physics}, number = {3}, publisher = {Copernicus}, issn = {1680-7324}, doi = {10.5194/acp-12-1541-2012}, pages = {1541 -- 1569}, year = {2012}, abstract = {Abstract. Ambient OH and HO2 concentrations were measured by laser induced fluorescence (LIF) during the PRIDE-PRD2006 (Program of Regional Integrated Experiments of Air Quality over the Pearl River Delta, 2006) campaign at a rural site downwind of the megacity of Guangzhou in Southern China. The observed OH concentrations reached daily peak values of (15-26) × 106 cm-3 which are among the highest values so far reported for urban and suburban areas. The observed OH shows a consistent high correlation with j(O1D) over a broad range of NOx conditions. The correlation cannot be reproduced by model simulations, indicating that OH stabilizing processes are missing in current models. The observed OH exhibited a weak dependence on NOx in contrast to model predictions. While modelled and measured OH agree well at NO mixing ratios above 1 ppb, a continuously increasing underprediction of the observed OH is found towards lower NO concentrations, reaching a factor of 8 at 0.02 ppb NO. A dependence of the modelled-to-measured OH ratio on isoprene cannot be concluded from the PRD data. However, the magnitude of the ratio fits into the isoprene dependent trend that was reported from other campaigns in forested regions. Hofzumahaus et al. (2009) proposed an unknown OH recycling process without NO, in order to explain the high OH levels at PRD in the presence of high VOC reactivity and low NO. Taking a recently discovered interference in the LIF measurement of HO2 into account, the need for an additional HO2 → OH recycling process persists, but the required source strength may be up to 20\% larger than previously determined. Recently postulated isoprene mechanisms by Lelieveld et al. (2008) and Peeters and M{\"u}ller (2010) lead to significant enhancements of OH expected for PRD, but an underprediction of the observed OH by a factor of two remains at low NO (0.1-0.2 ppb). If the photolysis of hydroperoxy aldehydes from isoprene is as efficient as proposed by Peeters and M{\"u}ller (2010), the corresponding OH formation at PRD would be more important than the primary OH production from ozone and HONO. While the new isoprene mechanisms need to be confirmed by laboratory experiments, there is probably need for other, so far unidentified chemical processes to explain entirely the high OH levels observed in Southern China.}, language = {en} } @misc{GottschaldAdamMarx2014, author = {Gottschald, Jonas and Adam, Mario and Marx, H.}, title = {Heiztechnik - Langzeitmessergebnisse eines vakuumisolierten Warmwasserspeichers}, series = {HLH Heizung - L{\"u}ftung - Haustechnik}, volume = {64}, journal = {HLH Heizung - L{\"u}ftung - Haustechnik}, number = {4}, publisher = {VDI-Verlag}, issn = {0017-9906}, pages = {20 -- 25}, year = {2014}, language = {de} } @article{MiguelesRowlandsHuberetal.2019, author = {Migueles, Jairo H. and Rowlands, Alex V. and Huber, Florian and Sabia, S{\´e}verine and van Hees, Vincent T.}, title = {GGIR: A Research Community-Driven Open Source R Package for Generating Physical Activity and Sleep Outcomes From Multi-Day Raw Accelerometer Data}, series = {Journal for the Measurement of Physical Behaviour}, volume = {2}, journal = {Journal for the Measurement of Physical Behaviour}, number = {3}, publisher = {Human Kinetics}, issn = {2575-6605}, doi = {10.1123/jmpb.2018-0063}, pages = {188 -- 196}, year = {2019}, language = {en} } @article{HuberBoireLopezetal.2015, author = {Huber, Florian and Boire, Adeline and L{\´o}pez, Magdalena Preciado and Koenderink, Gijsje H.}, title = {Cytoskeletal crosstalk: when three different personalities team up}, series = {Current Opinion in Cell Biology}, volume = {32}, journal = {Current Opinion in Cell Biology}, publisher = {Elsevier}, issn = {1879-0410}, doi = {10.1016/j.ceb.2014.10.005}, pages = {39 -- 47}, year = {2015}, language = {en} } @article{HuberVerhoevenMeijeretal.2020, author = {Huber, Florian and Verhoeven, Stefan and Meijer, Christiaan and Spreeuw, Hanno and Castilla, Efra{\´i}n and Geng, Cunliang and van der Hooft, Justin J. J. and Rogers, Simon and Belloum, Adam and Diblen, Faruk and Spaaks, Jurriaan H.}, title = {matchms - processing and similarity evaluation of mass spectrometry data}, series = {Journal of Open Source Software}, volume = {5}, journal = {Journal of Open Source Software}, number = {52}, publisher = {Cold Spring Harbor Laboratory}, issn = {2475-9066}, doi = {10.21105/joss.02411}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-34856}, pages = {2411}, year = {2020}, language = {en} } @article{PreciadoLopezHuberGrigorievetal.2014, author = {Preciado L{\´o}pez, Magdalena and Huber, Florian and Grigoriev, Ilya and Steinmetz, Michel O. and Akhmanova, Anna and Dogterom, Marileen and Koenderink, Gijsje H.}, title = {In vitro reconstitution of dynamic microtubules interacting with actin filament networks}, series = {Methods in Enzymology}, volume = {540}, journal = {Methods in Enzymology}, publisher = {Elsevier}, issn = {1557-7988}, doi = {10.1016/B978-0-12-397924-7.00017-0}, pages = {301 -- 320}, year = {2014}, language = {en} } @article{PreciadoLopezHuberGrigorievetal.2014, author = {Preciado L{\´o}pez, Magdalena and Huber, Florian and Grigoriev, Ilya and Steinmetz, Michel O. and Akhmanova, Anna and Koenderink, Gijsje H. and Dogterom, Marileen}, title = {Actin-microtubule coordination at growing microtubule ends}, series = {Nature Communications}, volume = {5}, journal = {Nature Communications}, publisher = {Springer Nature}, issn = {2041-1723}, doi = {10.1038/ncomms5778}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-34878}, pages = {4778}, year = {2014}, abstract = {To power dynamic processes in cells, the actin and microtubule cytoskeletons organize into complex structures. Although it is known that cytoskeletal coordination is vital for cell function, the mechanisms by which cross-linking proteins coordinate actin and microtubule activities remain poorly understood. In particular, it is unknown how the distinct mechanical properties of different actin architectures modulate the outcome of actin-microtubule interactions. To address this question, we engineered the protein TipAct, which links growing microtubule ends via end-binding proteins to actin filaments. We show that growing microtubules can be captured and guided by stiff actin bundles, leading to global actin-microtubule alignment. Conversely, growing microtubule ends can transport, stretch and bundle individual actin filaments, thereby globally defining actin filament organization. Our results provide a physical basis to understand actin-microtubule cross-talk, and reveal that a simple cross-linker can enable a mechanical feedback between actin and microtubule organization that is relevant to diverse biological contexts.}, language = {en} } @article{HuberRidderVerhoevenetal.2021, author = {Huber, Florian and Ridder, Lars and Verhoeven, Stefan and Spaaks, Jurriaan H. and Diblen, Faruk and Rogers, Simon and van der Hooft, Justin J. J.}, title = {Spec2Vec: Improved mass spectral similarity scoring through learning of structural relationships}, series = {PLOS Computational Biology}, volume = {17}, journal = {PLOS Computational Biology}, number = {2}, publisher = {Cold Spring Harbor Laboratory}, issn = {1553-7358}, doi = {10.1371/journal.pcbi.1008724}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-34687}, year = {2021}, abstract = {Spectral similarity is used as a proxy for structural similarity in many tandem mass spectrometry (MS/MS) based metabolomics analyses such as library matching and molecular networking. Although weaknesses in the relationship between spectral similarity scores and the true structural similarities have been described, little development of alternative scores has been undertaken. Here, we introduce Spec2Vec, a novel spectral similarity score inspired by a natural language processing algorithm-Word2Vec. Spec2Vec learns fragmental relationships within a large set of spectral data to derive abstract spectral embeddings that can be used to assess spectral similarities. Using data derived from GNPS MS/MS libraries including spectra for nearly 13,000 unique molecules, we show how Spec2Vec scores correlate better with structural similarity than cosine-based scores. We demonstrate the advantages of Spec2Vec in library matching and molecular networking. Spec2Vec is computationally more scalable allowing structural analogue searches in large databases within seconds.}, language = {en} } @article{GuoDoRuess2019, author = {Guo, Y. and Do, H. and Ruess, Martin}, title = {Isogeometric stability analysis of thin shells: From simple geometries to engineering models}, series = {International Journal for Numerical Methods in Engineering}, volume = {118}, journal = {International Journal for Numerical Methods in Engineering}, number = {8}, publisher = {Wiley}, issn = {1097-0207}, doi = {10.1002/nme.6020}, pages = {433 -- 458}, year = {2019}, language = {en} } @article{JainFranz2004, author = {Jain, V. K. and Franz, J. H.}, title = {Some Design Issues in Infrared Wireless Networks}, series = {IETE Technical Review}, volume = {21}, journal = {IETE Technical Review}, number = {5}, publisher = {Taylor \& Francis}, doi = {10.1080/02564602.2004.11417161}, pages = {335 -- 343}, year = {2004}, language = {en} } @article{PrataDezitterDaviesetal.2016, author = {Prata, A. J. and Dezitter, F. and Davies, I. and Weber, Konradin and Birnfeld, M. and Moriano, D. and Bernardo, C. and Vogel, A. and Prata, G. S. and Mather, T. A. and Thomas, H. E. and Cammas, J. and Weber, M.}, title = {Artificial cloud test confirms volcanic ash detection using infrared spectral imaging}, series = {Scientific reports}, volume = {6}, journal = {Scientific reports}, publisher = {Springer Nature}, doi = {10.1038/srep25620}, year = {2016}, abstract = {Airborne volcanic ash particles are a known hazard to aviation. Currently, there are no means available to detect ash in flight as the particles are too fine (radii < 30 μm) for on-board radar detection and, even in good visibility, ash clouds are difficult or impossible to detect by eye. The economic cost and societal impact of the April/May 2010 Icelandic eruption of Eyjafjallaj{\"o}kull generated renewed interest in finding ways to identify airborne volcanic ash in order to keep airspace open and avoid aircraft groundings. We have designed and built a bi-spectral, fast-sampling, uncooled infrared camera device (AVOID) to examine its ability to detect volcanic ash from commercial jet aircraft at distances of more than 50 km ahead. Here we report results of an experiment conducted over the Atlantic Ocean, off the coast of France, confirming the ability of the device to detect and quantify volcanic ash in an artificial ash cloud created by dispersal of volcanic ash from a second aircraft. A third aircraft was used to measure the ash in situ using optical particle counters. The cloud was composed of very fine ash (mean radii ~10 μm) collected from Iceland immediately after the Eyjafjallaj{\"o}kull eruption and had a vertical thickness of ~200 m, a width of ~2 km and length of between 2 and 12 km. Concentrations of ~200 μg m(-3) were identified by AVOID at distances from ~20 km to ~70 km. For the first time, airborne remote detection of volcanic ash has been successfully demonstrated from a long-range flight test aircraft.}, language = {en} } @inproceedings{DubberkePriebeVrabecetal.2015, author = {Dubberke, Frithjof H. and Priebe, Klaus-Peter and Vrabec, Jadran and Neef, Matthias and R{\"o}dder, Maximilian}, title = {Thermodynamic simulation and experimental validation of a cascaded two-stage organic Rankine cycle}, series = {ASME ORC 2015, Brussels}, booktitle = {ASME ORC 2015, Brussels}, address = {Brussels}, year = {2015}, language = {en} } @article{EversheimBauernhanslDeckertetal.2001, author = {Eversheim, Walter and Bauernhansl, Thomas and Deckert, Carsten and Kampker, Achim and H{\"a}rtung, Stefan and H. von der Ohe, Carsten}, title = {Vom Marktteilnehmer zum Marktgestalter: Innovatives Denken er{\"o}ffnet neue Wachstumsperspektiven im Maschinen- und Anlagenbau}, series = {ZWF Zeitschrift f{\"u}r wirtschaftlichen Fabrikbetrieb}, volume = {96}, journal = {ZWF Zeitschrift f{\"u}r wirtschaftlichen Fabrikbetrieb}, number = {10}, publisher = {Hanser}, doi = {10.3139/104.100475}, pages = {522 -- 524}, year = {2001}, abstract = {Innovative thinking opens up new growth prospects in mechanical and plant engineering. Mechanical and plant engineering has been traditionally very important to the industrial location of Germany [1]. With an export share of 70\%, it has a considerable direct influence on economic structure and job market. In addition, mechanical engineering is the "innovation engine" for other core industries in Germany - as supplier of production equipment for industries such as the car manufacture, plastics processing and electrical engineering sectors. Only through this production equipment can innovative products reach production readiness in the first place, and can "Made in Germany" continue to enjoy an excellent reputation all over the world.}, language = {de} } @article{DubberkeLinnemannAbbasetal.2018, author = {Dubberke, Frithjof H. and Linnemann, Matthias and Abbas, Wameedh Khider and Baumh{\"o}gger, Elmar and Priebe, Klaus-Peter and Roedder, Maximilian and Neef, Matthias and Vrabec, Jadran}, title = {Experimental setup of a cascaded two-stage organic Rankine cycle}, series = {Applied Thermal Engineering}, volume = {131}, journal = {Applied Thermal Engineering}, publisher = {Elsevier}, doi = {10.1016/j.applthermaleng.2017.11.137}, pages = {958 -- 964}, year = {2018}, abstract = {In combination with a bottoming cycle, operated with a pure fluid in transcritical mode, the usage of a zeotropic mixture as a working fluid appears to be exergetically favorable for power cycle efficiency in cascaded two-stage organic Rankine cycles (CORC). A CORC is set up and initially tested with cyclopentane and propane as working fluids in its high temperature and low temperature cycle, respectively. A thermal oil cycle serves as the heat source and is powered electrically with a maximum heat flow of 158 kW. The design of this experimental setup allows for a rapid replacement of individual components and for a wide range of conditions in terms of fluids and thermodynamic states. The components of all cycles and the measurement and control technology are described in detail. A testing procedure is presented, followed by a discussion of the measurement results, where it is shown that the intended concept of two cascaded organic Rankine cycles is operational and that the measured data are consistent.}, language = {en} } @article{NguyenStoterRuessetal.2018, author = {Nguyen, Lam H. and Stoter, Stein K.F. and Ruess, Martin and Sanchez Uribe, Manuel A. and Schillinger, Dominik}, title = {The diffuse Nitsche method: Dirichlet constraints on phase-field boundaries}, series = {International Journal for Numerical Methods in Engineering}, volume = {113}, journal = {International Journal for Numerical Methods in Engineering}, number = {4}, publisher = {Wiley}, issn = {1097-0207}, doi = {10.1002/nme.5628}, pages = {601 -- 633}, year = {2018}, language = {en} } @article{NguyenStoterBaumetal.2017, author = {Nguyen, Lam H. and Stoter, Stein K.F. and Baum, Thomas and Kirschke, Jan and Ruess, Martin and Yosibash, Zohar and Schillinger, Dominik}, title = {Phase-field boundary conditions for the voxel finite cell method: Surface-free stress analysis of CT-based bone structures}, series = {International Journal for Numerical Methods in Biomedical Engineering}, volume = {33}, journal = {International Journal for Numerical Methods in Biomedical Engineering}, number = {12}, publisher = {Wiley}, issn = {2040-7947}, doi = {10.1002/cnm.2880}, year = {2017}, language = {en} } @article{ZanderBogElhaddadetal.2014, author = {Zander, Nils and Bog, Tino and Elhaddad, Mohamed and Espinoza, R. and Hu, H. and Joly, A. and Wu, C. and Zerbe, P. and D{\"u}ster, Alexander and Kollmannsberger, Stefan and Parvizian, J. and Ruess, Martin and Schillinger, Dominik and Rank, Ernst}, title = {FCMLab: A finite cell research toolbox for MATLAB}, series = {Advances in Engineering Software}, volume = {74}, journal = {Advances in Engineering Software}, publisher = {Elsevier}, issn = {0965-9978}, doi = {10.1016/j.advengsoft.2014.04.004}, pages = {49 -- 63}, year = {2014}, language = {en} } @article{SenthurAnandRameshKumaretal.2022, author = {Senthur, N.S. and Anand, C and Ramesh Kumar, M and Elumalai, P.V. and Shajahan, Mohamed Iqbal and Benim, Ali Cemal and Nasr, Emad Abouel and Hussein, H.M.A. and Parthasarathy, M.}, title = {Influence of cobalt chromium nanoparticles in homogeneous charge compression ignition engine operated with citronella oil}, series = {Energy Science \& Engineering}, volume = {10}, journal = {Energy Science \& Engineering}, number = {4}, publisher = {Wiley}, issn = {2050-0505}, doi = {10.1002/ese3.1088}, pages = {1251 -- 1263}, year = {2022}, language = {en} } @inproceedings{HimmeleinSteffens2022, author = {Himmelein, H. and Steffens, Jochen}, title = {"Ich sehe, was Du h{\"o}rst!" - Verwendung der Pupillometrie zur Messung des Einflusses kognitiver Belastung auf die Ger{\"a}uschbewertung}, series = {Deutsche Jahrestagung f{\"u}r Akustik (DAGA), Stuttgart}, booktitle = {Deutsche Jahrestagung f{\"u}r Akustik (DAGA), Stuttgart}, address = {Stuttgart}, year = {2022}, language = {de} } @misc{Franz1995, author = {Franz, J{\"u}rgen H.}, title = {Was ist ein Baum? Eine Kurzgeschichte aus dem Leben des Herrn Schwarzweiß}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-9568}, year = {1995}, abstract = {Herr Schwarzweiß ist seit seiner Geburt nicht in der Lage Farben zu erkennen. Seine Welt ist schwarzweiß. Doch kann er sehr gut zwischen den verschiedenen Graut{\"o}nen unterscheiden. F{\"u}r ihn ist Weiß nicht gleich Weiß. Es gibt ein sehr helles Weiß, ein dunkleres Weiß, ein grau unterlegtes Weiß und viele andere Arten von Weiß. ...}, language = {de} } @inproceedings{ComeronKassianovSchaeferetal.2015, author = {Comeron, Adolfo and Kassianov, Evgueni I. and Sch{\"a}fer, Klaus and Picard, Richard H. and Weber, Konradin}, title = {Remote Sensing of Clouds and the Atmosphere XX. Remote Sensing of Clouds and the Atmosphere, Toulouse), 23.-24.09.2015}, volume = {Proceedings of SPIE ; volume 9640}, publisher = {SPIE}, address = {Bellingham, Washington, USA}, isbn = {978-1-62841-850-7}, issn = {0277-786X}, year = {2015}, language = {en} } @article{NaraparajuLauLangeetal.2018, author = {Naraparaju, R. and Lau, H. and Lange, Martin and Fischer, Christian and Kramer, D. and Schulz, U. and Weber, Konradin}, title = {Integrated testing approach using a customized micro turbine for a volcanic ash and CMAS related degradation study of thermal barrier coatings}, series = {Surface and Coatings Technology}, volume = {337}, journal = {Surface and Coatings Technology}, publisher = {Elsevier}, issn = {0257-8972}, doi = {10.1016/j.surfcoat.2018.01.030}, pages = {198 -- 208}, year = {2018}, language = {en} } @inproceedings{ComeronJackKassianovetal.2016, author = {Comeron, Adolfo and Jack, James and Kassianov, Evgueni I. and Sch{\"a}fer, Kiaus and Picard, Richard H and Weber, Konradin}, title = {Remote Sensing of Clouds and the Atmosphere XXI Introduction}, series = {Remote Sensing of Clouds and the Atmosphere XXI : 28-29 September 2016, Edinburgh, United Kingdom}, booktitle = {Remote Sensing of Clouds and the Atmosphere XXI : 28-29 September 2016, Edinburgh, United Kingdom}, publisher = {SPIE}, address = {Bellingham, Washington, USA}, isbn = {978-1-5106-0406-3}, year = {2016}, language = {en} } @article{QuevalSoteloKharmizetal.2016, author = {Queval, Loic and Sotelo, Guilherme G. and Kharmiz, Yassin and Dias, Daniel H. N. and Sass, Felipe and Zermeno, Victor M. R. and Gottkehaskamp, Raimund}, title = {Optimization of the Superconducting Linear Magnetic Bearing of a Maglev Vehicle}, series = {IEEE Transactions on Applied Superconductivity}, volume = {26}, journal = {IEEE Transactions on Applied Superconductivity}, number = {3}, publisher = {IEEE}, issn = {1051-8223}, doi = {10.1109/TASC.2016.2528989}, year = {2016}, language = {en} } @article{PetersHrten2009, author = {Peters, Christian and H?rten, D.}, title = {Sportlandschaft Mallorca. Zur wirtschaftlichen Bedeutung des Radsporttourismus auf der Baleareninsel Mallorca}, series = {Geographie und Schule}, volume = {31}, journal = {Geographie und Schule}, number = {179}, publisher = {Aulis-Verl.}, issn = {0171-8649}, pages = {28 -- 33}, year = {2009}, language = {de} } @article{GrotkampCibisBrueggemannetal.2020, author = {Grotkamp, Sabine and Cibis, Wolfgang and Br{\"u}ggemann, Silke and Coenen, M. Michaela and Gm{\"u}nder, Hans-Peter and Keller, Klaus and N{\"u}chtern, Elisabeth and Schwegler, Urban and Seger, Wolfgang and Staubli, Stefan and von Raison, B. Bia and Weißmann, R. and Bahemann, A. and Fuchs, H. and Rink, M. and Schian, Marcus and Schmitt, Klaus}, title = {Personal Factors of the Bio-Psycho-Social Model (WHO): A Revised Classification by the German Society for Social Medicine and Prevention (DGSMP)}, series = {Gesundheitswesen}, volume = {82}, journal = {Gesundheitswesen}, number = {1}, publisher = {Thieme}, doi = {10.1055/a-1011-3161}, pages = {107 -- 116}, year = {2020}, language = {de} } @article{SuhBenim1989, author = {Suh, S.-H. and Benim, Ali Cemal}, title = {The primitive variables formulation of the Navier-Stokes equations using the finite analytic method}, series = {Applied Mathematical Modelling}, volume = {13}, journal = {Applied Mathematical Modelling}, number = {9}, publisher = {Elsevier}, issn = {0307-904X}, doi = {10.1016/0307-904X(89)90066-8}, pages = {550 -- 554}, year = {1989}, subject = {Navier-Stokes-Gleichung}, language = {en} } @article{BenimNeuhoff1993, author = {Benim, Ali Cemal and Neuhoff, H. G.}, title = {Analysis of erosion behaviour in a turbocharger radial turbine}, series = {International Journal for Numerical Methods in Fluids}, volume = {16}, journal = {International Journal for Numerical Methods in Fluids}, number = {4}, publisher = {Wiley}, issn = {0271-2091}, doi = {10.1002/fld.1650160402}, pages = {259 -- 285}, year = {1993}, abstract = {An analysis of the erosion behaviour of a turbocharger radial turbine is presented. The solution domain includes both sides of the radial turbine scroll with double intake and the rotor channel. In the analysis a dilute gas-particle flow assumption is employed. The gas turbulence is defined by the k-ε model. In solving the gas phase equation, the computer code Harwell-FLOW3D is employed, which is based on a finite volume formulation using non-orthogonal body-fitted structured gridding and a pressure correction method. The particle phase is described by a Lagrangian approach, while particle paths are computed deterministically, neglecting the turbulent dispersion. For the computation of particle trajectories the code PTRACK is employed, which has been developed at ABB. Computations are carried out for several particle size classes. The results show that particles are thrown back into the scroll by the rotor at high rates. This seems to be the main source of erosion effects in the scroll. It has been observed that particles are unequally distributed between the scroll sides on their re-entry, resulting in greater erosion on one of the scroll sides. The maximum erosion along the scroll is found to be likely to occur near the scroll end.}, subject = {Erosion}, language = {en} } @article{CurcicVanWaeyenbergeVansteenkisteetal.2008, author = {Curcic, Michael and Van Waeyenberge, Bartel and Vansteenkiste, Arne and Weigand, Markus and Sackmann, Vitalij and Stoll, Hermann and F{\"a}hnle, Manfred and Tyliszczak, Tolek and Woltersdorf, Georg and Back, Christian H. and Sch{\"u}tz, Gisela}, title = {Polarization Selective Magnetic Vortex Dynamics and Core Reversal in Rotating Magnetic Fields}, series = {Physical Review Letters}, volume = {101}, journal = {Physical Review Letters}, number = {19}, publisher = {American Physical Society}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.101.197204}, year = {2008}, language = {en} } @article{WeigandVanWaeyenbergeVansteenkisteetal.2009, author = {Weigand, Markus and Van Waeyenberge, Bartel and Vansteenkiste, Arne and Curcic, Michael and Sackmann, Vitalij and Stoll, Hermann and Tyliszczak, Tolek and Kaznatcheev, Konstantine and Bertwistle, Drew and Woltersdorf, Georg and Back, Christian H. and Sch{\"u}tz, Gisela}, title = {Vortex Core Switching by Coherent Excitation with Single In-Plane Magnetic Field Pulses}, series = {Physical Review Letters}, volume = {102}, journal = {Physical Review Letters}, number = {7}, publisher = {American Physical Society}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.102.077201}, year = {2009}, language = {en} } @article{VansteenkisteWeigandCurcicetal.2009, author = {Vansteenkiste, A and Weigand, M and Curcic, Michael and Stoll, H and Sch{\"u}tz, G and Van Waeyenberge, B}, title = {Chiral symmetry breaking of magnetic vortices by sample roughness}, series = {New Journal of Physics}, volume = {11}, journal = {New Journal of Physics}, number = {6}, publisher = {IOP Publishing}, issn = {1367-2630}, doi = {10.1088/1367-2630/11/6/063006}, year = {2009}, language = {en} } @article{KammererWeigandCurcicetal.2011, author = {Kammerer, Matthias and Weigand, Markus and Curcic, Michael and Noske, Matthias and Sproll, Markus and Vansteenkiste, Arne and Van Waeyenberge, Bartel and Stoll, Hermann and Woltersdorf, Georg and Back, Christian H. and Schuetz, Gisela}, title = {Magnetic vortex core reversal by excitation of spin waves}, series = {Nature Communications}, volume = {2}, journal = {Nature Communications}, number = {1}, publisher = {Springer Nature}, issn = {2041-1723}, doi = {10.1038/ncomms1277}, year = {2011}, language = {en} } @inproceedings{WeberReichardtFischeretal.2012, author = {Weber, Konradin and Reichardt, R. and Fischer, Christian and Moser, H. M. and Eliasson, Jonas}, title = {Computational Visualization of Volcanic Ash Plume Concentrations Measured by light Aircrafts over Germany and Iceland during the Recent Eruptions of the Volcanoes Eyjafjallaj{\"o}kull and Grimsv{\"o}tn}, series = {Recent advances in Fluid Mechanics, Heat \& Mass Transfer, Biology and Ecology}, booktitle = {Recent advances in Fluid Mechanics, Heat \& Mass Transfer, Biology and Ecology}, editor = {Jha, Manoj K. and Lazard, Myriam and Zaharim, Azami and Sopian, Kamaruzzaman}, publisher = {WSEAS}, isbn = {978-1-61804-065-7}, pages = {236 -- 240}, year = {2012}, subject = {Vulkanasche}, language = {en} } @incollection{DenizCanalDiederichKaracayetal.2025, author = {Deniz Canal, Cansu and Diederich, Michael and Karacay, Onur and Benim, Ali Cemal and Hamberger, Andreas and Heese, Markus and Schr{\"a}der, K. H.}, title = {Investigation of Boiler Efficiency Improvements via Enthalpy Wheel with Application to a Biomass Boiler}, series = {Mathematical Theory and Simulation of Scientific Problems: FIAM-2023, Dubai, UAE, December 21-22}, volume = {Springer Proceedings in Mathematics \& Statistics, Bd. 487}, booktitle = {Mathematical Theory and Simulation of Scientific Problems: FIAM-2023, Dubai, UAE, December 21-22}, editor = {Sharma, Rajesh Kumar and Srivastava, Shailesh Kumar and Benim, Ali Cemal}, publisher = {Springer Nature}, address = {Singapore}, isbn = {9789819625789}, issn = {2194-1009}, doi = {10.1007/978-981-96-2579-6_13}, pages = {189 -- 200}, year = {2025}, subject = {Numerische Str{\"o}mungssimulation}, language = {en} } @article{UffmannAbichtGroteetal.2002, author = {Uffmann, Kai and Abicht, Claus and Grote, Wolfgang and Quick, Harald H. and Ladd, Mark E.}, title = {Design of an MR-compatible piezoelectric actuator for MR elastography}, series = {Concepts in Magnetic Resonance Part A: Bridging Education and Research}, volume = {15}, journal = {Concepts in Magnetic Resonance Part A: Bridging Education and Research}, number = {4}, publisher = {Wiley}, doi = {https://doi.org/10.1002/cmr.10045}, pages = {239 -- 254}, year = {2002}, abstract = {Magnetic Resonance (MR) elastography is a method for measuring tissue elasticity via phase images acquired with an MR scanner. The propagation of periodic mechanical waves through the tissue can be captured by means of a modified phase contrast sequence. These waves are generated with a mechanical oscillator (actuator) and coupled into the tissue through the skin. The actuator must be capable of generating a sinusoidal excitation with excellent phase and amplitude stability, while not disturbing the MR imaging process. In this work, an actuator based on a piezoelectric principle was developed. Based on the imaging evaluation of several material samples, the housing for the piezoelectric ceramic was constructed of aluminum. Smaller parts of the housing were manufactured from brass and titanium to fulfill the mechanical constraints. A lever was used to transfer the oscillation generated by the piezoelectric ceramic to the point of excitation. The lever amplifies the piezoelectric motion, allowing for a more compact design. Three different lever designs were characterized by an acceleration sensor both outside and inside the magnet. It was shown that the rigidity of the lever, as determined by its material and form, was decisive in determining the resonant frequency of the system and therefore the maximum practical frequency of operation. It was also shown that the motion of the oscillator is unaffected by the electromagnetic fields of the MR imager. The final design can be placed directly in the magnet bore within a few centimeters of the tissue volume to be imaged without generating significant artifacts. An amplitude range of 0-1 mm in the frequency range from 0 to over 300 Hz was achieved, sufficient for performing most MR elastography applications. © 2002 Wiley Periodicals, Inc. Concepts in Magnetic Resonance (Magn Reson Engineering) 15: 239-254, 2002}, language = {en} } @article{HechlerKosfelderDeneckeetal.2008, author = {Hechler, T. and Kosfelder, J. and Denecke, H. and Dobe, M. and H{\"u}bner, B. and Martin, A. and Menke, A. and Schroeder, S. and Marbach, S. and Zernikow, B.}, title = {Pain-related coping strategies in children and adolescents with chronic pain. Validation of a German version of the Paediatric Pain Coping Inventory (PPCI revised)}, series = {Der Schmerz}, volume = {22}, journal = {Der Schmerz}, number = {4}, publisher = {Springer}, doi = {10.1007/s00482-008-0621-4}, pages = {442 -- 457}, year = {2008}, language = {de} } @article{HuebnerHechlerDobeetal.2009, author = {H{\"u}bner, B. and Hechler, T. and Dobe, M. and Damschen, U. and Kosfelder, Joachim and Denecke, H. and Schroeder, S. and Zernikow, B.}, title = {Pain-related disability in adolescents suffering from chronic pain. Preliminary examination of the Pediatric Pain Disability Index (P-PDI)}, series = {Der Schmerz}, volume = {23}, journal = {Der Schmerz}, number = {1}, publisher = {Springer}, doi = {10.1007/s00482-008-0730-0}, pages = {20 -- 32}, year = {2009}, language = {de} } @article{WagerTietzeDeneckeetal.2010, author = {Wager, J. and Tietze, A-L and Denecke, H. and Schroeder, S. and Vocks, S. and Kosfelder, Joachim and Zernikow, B. and Hechler, T.}, title = {Pain perception of adolescents with chronic functional pain : adaptation and psychometric validation of the Pain Perception Scale (SES) by Geissner}, series = {Der Schmerz}, volume = {24}, journal = {Der Schmerz}, number = {3}, publisher = {Springer}, doi = {10.1007/s00482-010-0920-4}, pages = {236 -- 250}, year = {2010}, language = {de} } @inproceedings{VogelWeberEliassonetal.2012, author = {Vogel, Andreas and Weber, Konradin and Eliasson, Jonas and Palsson, Asgeir and Moser, H. M. and Palsson, Thorgeir and von L{\"o}wis, S. and Fischer, Christian}, title = {Airborne and groundbased measurements of ash particles on Iceland and over Germany during the Gr{\´i}msv{\"o}tn eruption May 2011 [Abstract]}, series = {Geophysical Research Abstracts:EGU General Assembly 2012, held 22-27 April, 2012 in Vienna, Austria}, booktitle = {Geophysical Research Abstracts:EGU General Assembly 2012, held 22-27 April, 2012 in Vienna, Austria}, publisher = {Copernicus}, address = {G{\"o}ttingen}, pages = {12854}, year = {2012}, abstract = {The eruption of the Grimsv{\"o}tn volcano in May 2010 posed with its ash plume a thread to the aviation in northern Europe. Because of ash plume forecasts of the VAAC London the airport of Keflavik in Iceland as well as airports in England, Scotland and Scandinavia were closed for some time, which caused the cancellation or change of about 500 flights in Europe. Even in Germany the airports of Bremen, Hamburg and Berlin were closed for several hours on 25 May 2011. During this eruption period in May 2011, a team of the Duesseldorf University of Applied Sciences, the University of Iceland, the University of Reykjavik and the IMO has performed airborne in-situ measurements over Iceland and Germany as well as ground based measurements in the south of Iceland. The ground based measurements were performed continuously during the whole eruption period at two significant positions (Skogar and Hvollsv{\"o}llur) with optical particle counters (OPCs). The measurement method was based on measuring the airborne concentrations of the classic aerosol components (PM10, PM2.5 and PM1) and TSP (total suspended particles) every 6 seconds. Additional measurement flights on Iceland were started already one day after the beginning of the eruption (twelve in-situ measurement flights) and marked the spatial and temporal spread of volcanic ash in the atmosphere. For the flights light slow flying piston engine powered airplanes where used. The flights over Iceland focused on the western part of Iceland in the region of Reykjavik and Keflavik and over the international airport in Keflavik and were mostly coordinated by ISAVIA. The measurement flights helped to keep Keflavik International Airport open for many additional hours despite of adverse predictions by the London VAAC model, because it was possible to observe the particle concentration on-line during the flights. In Germany a measurement flight was performed on 25 May 2012 over the northern part of Germany where the volcanic ash cloud was forecasted from the dispersion model of the London VAAC. This flight was performed on the behalf of the German Weather Service (DWD). The measurement flights revealed most time relative low airborne ash concentrations over western Iceland, although the groundbased measured ash concentrations in the south of Iceland nearer to the Grimsv{\"o}tn were very high. In Germany the measured concentrations during the flight were low enough to be consistent with the re-opening of the airports Bremen, Hamburg and Berlin, which were closed by the authorities for several hours on 25 May 2011 because of high concentration predictions by the VAAC-model. The measurement flights clearly proved that OPCs, based on slow flying piston-motor driven aircrafts, are very suitable for the determination of airborne ash particles during volcanic eruptions. This is an important issue for air traffic safety.}, language = {en} } @article{FuchsAcirBohnetal.2014, author = {Fuchs, H. and Acir, Ismail-Hakki and Bohn, Birger and Brauers, Theo and Dorn, Hans-Peter and H{\"a}seler, R. and Hofzumahaus, A. and Holland, F. and Kaminski, M. and Li, X. and Lu, K. and Lutz, A. and Nehr, Sascha and Rohrer, F. and Tillmann, R. and Wegener, R. and Wahner, A.}, title = {OH regeneration from methacrolein oxidation investigated in the atmosphere simulation chamber SAPHIR}, series = {Atmospheric Chemistry and Physics}, volume = {14}, journal = {Atmospheric Chemistry and Physics}, number = {15}, publisher = {Copernicus}, issn = {1680-7324}, doi = {10.5194/acp-14-7895-2014}, pages = {7895 -- 7908}, year = {2014}, abstract = {Abstract. Hydroxyl radicals (OH) are the most important reagent for the oxidation of trace gases in the atmosphere. OH concentrations measured during recent field campaigns in isoprene-rich environments were unexpectedly large. A number of studies showed that unimolecular reactions of organic peroxy radicals (RO2) formed in the initial reaction step of isoprene with OH play an important role for the OH budget in the atmosphere at low mixing ratios of nitrogen monoxide (NO) of less than 100 pptv. It has also been suggested that similar reactions potentially play an important role for RO2 from other compounds. Here, we investigate the oxidation of methacrolein (MACR), one major oxidation product of isoprene, by OH in experiments in the simulation chamber SAPHIR under controlled atmospheric conditions. The experiments show that measured OH concentrations are approximately 50\% larger than calculated by the Master Chemical Mechanism (MCM) for conditions of the experiments (NO mixing ratio of 90 pptv). The analysis of the OH budget reveals an OH source that is not accounted for in MCM, which is correlated with the production rate of RO2 radicals from MACR. In order to balance the measured OH destruction rate, 0.77 OH radicals (1σ error: ± 0.31) need to be additionally reformed from each reaction of OH with MACR. The strong correlation of the missing OH source with the production of RO2 radicals is consistent with the concept of OH formation from unimolecular isomerization and decomposition reactions of RO2. The comparison of observations with model calculations gives a lower limit of 0.03 s-1 for the reaction rate constant if the OH source is attributed to an isomerization reaction of MACR-1-OH-2-OO and MACR-2-OH-2-OO formed in the MACR + OH reaction as suggested in the literature (Crounse et al., 2012). This fast isomerization reaction would be a competitor to the reaction of this RO2 species with a minimum of 150 pptv NO. The isomerization reaction would be the dominant reaction pathway for this specific RO2 radical in forested regions, where NO mixing ratios are typically much smaller.}, language = {en} } @article{NehrBohnDornetal.2014, author = {Nehr, Sascha and Bohn, Birger and Dorn, Hans-Peter and Fuchs, H. and H{\"a}seler, R. and Hofzumahaus, A. and Li, X. and Rohrer, F. and Tillmann, R. and Wahner, A.}, title = {Atmospheric photochemistry of aromatic hydrocarbons: OH budgets during SAPHIR chamber experiments}, series = {Atmospheric Chemistry and Physics}, volume = {14}, journal = {Atmospheric Chemistry and Physics}, number = {13}, publisher = {Copernicus}, issn = {1680-7324}, doi = {10.5194/acp-14-6941-2014}, pages = {6941 -- 6952}, year = {2014}, abstract = {Abstract. Current photochemical models developed to simulate the atmospheric degradation of aromatic hydrocarbons tend to underestimate OH radical concentrations. In order to analyse OH budgets, we performed experiments with benzene, toluene, p-xylene and 1,3,5-trimethylbenzene in the atmosphere simulation chamber SAPHIR. Experiments were conducted under low-NO conditions (typically 0.1-0.2 ppb) and high-NO conditions (typically 7-8 ppb), and starting concentrations of 6-250 ppb of aromatics, dependent on OH rate constants. For the OH budget analysis a steady-state approach was applied in which OH production and destruction rates (POH and DOH) have to be equal. The POH were determined from measurements of HO2, NO, HONO, and O3 concentrations, considering OH formation by photolysis and recycling from HO2. The DOH were calculated from measurements of the OH concentrations and total OH reactivities. The OH budgets were determined from DOH/POH ratios. The accuracy and reproducibility of the approach were assessed in several experiments using CO as a reference compound where an average ratio DOH/POH = 1.13 ± 0.19 was obtained. In experiments with aromatics, these ratios ranged within 1.1-1.6 under low-NO conditions and 0.9-1.2 under high-NO conditions. The results indicate that OH budgets during photo-oxidation experiments with aromatics are balanced within experimental accuracies. Inclusion of a further, recently proposed OH production via HO2 + RO2 reactions led to improvements under low-NO conditions but the differences were small and insignificant within the experimental errors.}, language = {en} } @article{FuchsHofzumahausRohreretal.2013, author = {Fuchs, H. and Hofzumahaus, A. and Rohrer, F. and Bohn, Birger and Brauers, Theo and Dorn, Hans-Peter and H{\"a}seler, R. and Holland, F. and Kaminski, M. and Li, X. and Lu, K. and Nehr, Sascha and Tillmann, R. and Wegener, R. and Wahner, A.}, title = {Experimental evidence for efficient hydroxyl radical regeneration in isoprene oxidation}, series = {Nature Geoscience}, volume = {6}, journal = {Nature Geoscience}, number = {12}, publisher = {Springer Nature}, issn = {1752-0894}, doi = {10.1038/NGEO1964}, pages = {1023 -- 1026}, year = {2013}, language = {en} } @article{ZellnerHerrmannWiesenetal.2016, author = {Zellner, R. and Herrmann, H. and Wiesen, P. and Nehr, Sascha}, title = {New and Emerging Technologies of Societal Relevance: Impact on Air Quality and Climate}, series = {Chemie Ingenieur Technik}, volume = {88}, journal = {Chemie Ingenieur Technik}, number = {9}, publisher = {Wiley}, issn = {0009-286X}, doi = {10.1002/cite.201650083}, pages = {1257 -- 1258}, year = {2016}, language = {en} } @article{FuchsDornBachneretal.2012, author = {Fuchs, H. and Dorn, Hans-Peter and Bachner, M. and Bohn, Birger and Brauers, Theo and Gomm, S. and Hofzumahaus, A. and Holland, F. and Nehr, Sascha and Rohrer, F. and Tillmann, R. and Wahner, A.}, title = {Comparison of OH concentration measurements by DOAS and LIF during SAPHIR chamber experiments at high OH reactivity and low NO concentration}, series = {Atmospheric Measurement Techniques}, volume = {5}, journal = {Atmospheric Measurement Techniques}, number = {7}, publisher = {Copernicus}, issn = {1867-8548}, doi = {10.5194/amt-5-1611-2012}, pages = {1611 -- 1626}, year = {2012}, abstract = {Abstract. During recent field campaigns, hydroxyl radical (OH) concentrations that were measured by laser-induced fluorescence (LIF) were up to a factor of ten larger than predicted by current chemical models for conditions of high OH reactivity and low NO concentration. These discrepancies, which were observed in forests and urban-influenced rural environments, are so far not entirely understood. In summer 2011, a series of experiments was carried out in the atmosphere simulation chamber SAPHIR in J{\"u}lich, Germany, in order to investigate the photochemical degradation of isoprene, methyl-vinyl ketone (MVK), methacrolein (MACR) and aromatic compounds by OH. Conditions were similar to those experienced during the PRIDE-PRD2006 campaign in the Pearl River Delta (PRD), China, in 2006, where a large difference between OH measurements and model predictions was found. During experiments in SAPHIR, OH was simultaneously detected by two independent instruments: LIF and differential optical absorption spectroscopy (DOAS). Because DOAS is an inherently calibration-free technique, DOAS measurements are regarded as a reference standard. The comparison of the two techniques was used to investigate potential artifacts in the LIF measurements for PRD-like conditions of OH reactivities of 10 to 30 s-1 and NO mixing ratios of 0.1 to 0.3 ppbv. The analysis of twenty experiment days shows good agreement. The linear regression of the combined data set (averaged to the DOAS time resolution, 2495 data points) yields a slope of 1.02 ± 0.01 with an intercept of (0.10 ± 0.03) × 106 cm-3 and a linear correlation coefficient of R2 = 0.86. This indicates that the sensitivity of the LIF instrument is well-defined by its calibration procedure. No hints for artifacts are observed for isoprene, MACR, and different aromatic compounds. LIF measurements were approximately 30-40\% (median) larger than those by DOAS after MVK (20 ppbv) and toluene (90 ppbv) had been added. However, this discrepancy has a large uncertainty and requires further laboratory investigation. Observed differences between LIF and DOAS measurements are far too small to explain the unexpected high OH concentrations during the PRIDE-PRD2006 campaign.}, language = {en} } @article{FuchsBohnHofzumahausetal.2011, author = {Fuchs, H. and Bohn, Birger and Hofzumahaus, A. and Holland, F. and Lu, K. D. and Nehr, Sascha and Rohrer, F. and Wahner, A.}, title = {Detection of HO2 by laser-induced fluorescence: calibration and interferences from RO2 radicals}, series = {Atmospheric Measurement Techniques}, volume = {4}, journal = {Atmospheric Measurement Techniques}, number = {6}, publisher = {Copernicus}, issn = {1867-8548}, doi = {10.5194/amt-4-1209-2011}, pages = {1209 -- 1225}, year = {2011}, abstract = {Abstract. HO2 concentration measurements are widely accomplished by chemical conversion of HO2 to OH including reaction with NO and subsequent detection of OH by laser-induced fluorescence. RO2 radicals can be converted to OH via a similar radical reaction sequence including reaction with NO, so that they are potential interferences for HO2 measurements. Here, the conversion efficiency of various RO2 species to HO2 is investigated. Experiments were conducted with a radical source that produces OH and HO2 by water photolysis at 185 nm, which is frequently used for calibration of LIF instruments. The ratio of HO2 and the sum of OH and HO2 concentrations provided by the radical source was investigated and was found to be 0.50 ± 0.02. RO2 radicals are produced by the reaction of various organic compounds with OH in the radical source. Interferences via chemical conversion from RO2 radicals produced by the reaction of OH with methane and ethane (H-atom abstraction) are negligible consistent with measurements in the past. However, RO2 radicals from OH plus alkene- and aromatic-precursors including isoprene (mainly OH-addition) are detected with a relative sensitivity larger than 80 \% with respect to that for HO2 for the configuration of the instrument with which it was operated during field campaigns. Also RO2 from OH plus methyl vinyl ketone and methacrolein exhibit a relative detection sensitivity of 60 \%. Thus, previous measurements of HO2 radical concentrations with this instrument were biased in the presence of high RO2 radical concentrations from isoprene, alkenes or aromatics, but were not affected by interferences in remote clean environment with no significant emissions of biogenic VOCs, when the OH reactivity was dominated by small alkanes. By reducing the NO concentration and/or the transport time between NO addition and OH detection, interference from these RO2 species are suppressed to values below 20 \% relative to the HO2 detection sensitivity. The HO2 conversion efficiency is also smaller by a factor of four, but this is still sufficient for atmospheric HO2 concentration measurements for a wide range of conditions.}, language = {en} }