@article{TubianaRinaldiGuettleretal.2019, author = {Tubiana, C. and Rinaldi, G. and Guettler, C. and Snodgrass, C. and Shi, X. and Hu, X. and Marschall, R. and Fulle, M. and Bockeele-Morvan, D. and Naletto, G. and Capaccioni, F. and Sierks, H. and Arnold, G. and Barucci, M. A. and Bertaux, J-L and Bertini, I and Bodewits, D. and Capria, M. T. and Ciarniello, M. and Cremonese, G. and Crovisier, J. and Da Deppo, V and Debei, S. and De Cecco, M. and Deller, J. and De Sanctis, M. C. and Davidsson, B. and Doose, L. and Erard, S. and Filacchione, G. and Fink, U. and Formisano, M. and Fornasier, S. and Gutierrez, P. J. and Ip, W-H and Ivanovski, S. and Kappel, David and Keller, H. U. and Kolokolova, L. and Koschny, D. and Krueger, H. and La Forgia, F. and Lamy, P. L. and Lara, L. M. and Lazzarin, M. and Levasseur-Regourd, A. C. and Lin, Z-Y and Longobardo, A. and Lopez-Moreno, J. J. and Marzari, F. and Migliorini, A. and Mottola, S. and Rodrigo, R. and Taylor, F. and Toth, I and Zakharov, V}, title = {Diurnal variation of dust and gas production in comet 67P/Churyumov-Gerasimenko at the inbound equinox as seen by OSIRIS and VIRTIS-M on board Rosetta}, series = {Astronomy and astrophysics : an international weekly journal}, volume = {630}, journal = {Astronomy and astrophysics : an international weekly journal}, publisher = {EDP Sciences}, address = {Les Ulis}, issn = {1432-0746}, doi = {10.1051/0004-6361/201834869}, pages = {14}, year = {2019}, abstract = {Context. On 27 April 2015, when comet 67P/Churyumov-Gerasimenko was at 1.76 au from the Sun and moving toward perihelion, the OSIRIS and VIRTIS-M instruments on board the Rosetta spacecraft simultaneously observed the evolving dust and gas coma during a complete rotation of the comet. Aims. We aim to characterize the spatial distribution of dust, H2O, and CO2 gas in the inner coma. To do this, we performed a quantitative analysis of the release of dust and gas and compared the observed H2O production rate with the rate we calculated using a thermophysical model. Methods. For this study we selected OSIRIS WAC images at 612 nm (dust) and VIRTIS-M image cubes at 612 nm, 2700 nm (H2O emission band), and 4200 nm (CO2 emission band). We measured the average signal in a circular annulus to study the spatial variation around the comet, and in a sector of the annulus to study temporal variation in the sunward direction with comet rotation, both at a fixed distance of 3.1 km from the comet center. Results. The spatial correlation between dust and water, both coming from the sunlit side of the comet, shows that water is the main driver of dust activity in this time period. The spatial distribution of CO2 is not correlated with water and dust. There is no strong temporal correlation between the dust brightness and water production rate as the comet rotates. The dust brightness shows a peak at 0 degrees subsolar longitude, which is not pronounced in the water production. At the same epoch, there is also a maximum in CO2 production. An excess of measured water production with respect to the value calculated using a simple thermophysical model is observed when the head lobe and regions of the southern hemisphere with strong seasonal variations are illuminated (subsolar longitude 270 degrees-50 degrees). A drastic decrease in dust production when the water production (both measured and from the model) displays a maximum occurs when typical northern consolidated regions are illuminated and the southern hemisphere regions with strong seasonal variations are instead in shadow (subsolar longitude 50 degrees-90 degrees). Possible explanations of these observations are presented and discussed.}, language = {en} } @article{HermannsKeller2022, author = {Hermanns, Jolanda and Keller, David}, title = {The development, use, and evaluation of digital games and quizzes in an introductory course on organic chemistry for preservice chemistry teachers}, series = {Journal of chemical education / Division of Chemical Education, Inc., American Chemical Society}, volume = {99}, journal = {Journal of chemical education / Division of Chemical Education, Inc., American Chemical Society}, number = {4}, publisher = {American Chemical Society}, address = {Washington}, issn = {0021-9584}, doi = {10.1021/acs.jchemed.2c00058}, pages = {1715 -- 1724}, year = {2022}, abstract = {Due to the COVID pandemic, the introductory course on organic chemistry was developed and conducted as anonline course. To ensure methodical variety in this course,educational games and quizzes have been developed, used, and evaluated. The attendance of the course, and therefore also the use of the quizzes and games, was voluntary. The quizzes'main goalwas to give the students the opportunity to check whether they had memorized the knowledge needed in the course. Another goal was to make transparent which knowledge the students shouldmemorize by rote. The evaluation shows that the students hadnot internalized all knowledge which they should apply in severaltasks on organic chemistry. They answered multiselect questions in general less well than single-select questions. The games shouldcombine fun with learning. The evaluation of the games shows that the students rated them very well. The students used thosegames again for their exam preparation, as the monitoring of accessing the games showed. Students'experiences with usingelectronic devices in general or for quizzes and games have also been evaluated, because their experience could influence thestudents'assessment of the quizzes and games used in our study. However, the students used electronic devices regularly and shouldtherefore be technically competent to use our quizzes and games. The evaluation showed that the use of digital games for learningpurposes is not very common, neither at school nor at university, although the students had worked with such tools before. Thestudents are also very interested in using and developing such digital games not only for their own study, but also for their future work at school}, language = {en} } @article{HermannsKeller2021, author = {Hermanns, Jolanda and Keller, David}, title = {School-related content knowledge in organic chemistry}, series = {Journal of chemical education / Division of Chemical Education, Inc., American Chemical Society}, volume = {98}, journal = {Journal of chemical education / Division of Chemical Education, Inc., American Chemical Society}, number = {3}, publisher = {American Chemical Society}, address = {Washington}, issn = {0021-9584}, doi = {10.1021/acs.jchemed.0c01415}, pages = {763 -- 773}, year = {2021}, abstract = {In this paper the development, use, and evaluation of tasks based on the construct of school-related content knowledge are described. The tasks were used in seminars on organic chemistry for bachelor and master preservice chemistry teachers at a German university. For the evaluation a questionnaire with open and closed items was used. The tasks were rated by the preservice chemistry teachers as relevant for their future profession as a chemistry teacher if the content of the tasks is part of the school curriculum. If the content does not belong to the school curriculum, they rated the nature of the tasks still as relevant; they seem to recognize the importance of conceptual knowledge for their future profession. However, the master's preservice teachers argued with this conceptual knowledge more often than the bachelor's preservice teachers. Although the study is cross-sectional, a certain shift from the focus on the content to conceptual knowledge from bachelor's to master's preservice teachers can be observed.}, language = {en} } @article{HermannsKeller2021, author = {Hermanns, Jolanda and Keller, David}, title = {How do preservice chemistry teachers rate tasks following the construct of school-related content knowledge in a concept-orientated course on organic chemistry?}, series = {Journal of chemical education / Division of Chemical Education, Inc., American Chemical Society}, volume = {98}, journal = {Journal of chemical education / Division of Chemical Education, Inc., American Chemical Society}, number = {11}, publisher = {American Chemical Society}, address = {Washington}, issn = {0021-9584}, doi = {10.1021/acs.jchemed.1c00593}, pages = {3442 -- 3449}, year = {2021}, abstract = {In this paper, we describe a study on tasks following the construct of school-related content knowledge. We know from previous studies that such tasks were rated by the preservice chemistry teachers as important for their future profession. Those studies were conducted in a traditional course on organic chemistry which was organized around chemical families. Therefore, we used and evaluated the tasks again in a new course on organic chemistry which is organized around basic concepts in organic chemistry. The results of this evaluation show that the students rate the tasks equally well but use other arguments for their rating. They do not focus only on the content of the tasks and whether this content belongs to the school curriculum or not. The students of the conceptual course rated the content more often (95\%) as important for their future profession compared with the students in the traditional course (57\%). Both groups of students rated the importance of the nature of the task the same way.}, language = {en} } @article{HermannsSchmidtGlowinskietal.2020, author = {Hermanns, Jolanda and Schmidt, Bernd and Glowinski, Ingrid and Keller, David}, title = {Online teaching in the course "organic chemistry" for nonmajor chemistry students}, series = {Journal of chemical education}, volume = {97}, journal = {Journal of chemical education}, number = {9}, publisher = {American Chemical Society}, address = {Washington}, issn = {0021-9584}, doi = {10.1021/acs.jchemed.0c00658}, pages = {3140 -- 3146}, year = {2020}, abstract = {In this communication the development of an online course on the topic organic chemistry for nonmajor chemistry students is described and discussed. For this online course, the existing classroom course was further developed. New elements such as podcasts, task navigators, and a forum for discussing the solving of tasks or problems with the content were added. This new online course was evaluated. Therefore, a questionnaire was developed. This consists of questions with regard to the longtime learning behavior of the students and to the online learning. The results of this evaluation show that a preference for online learning and a preference for classroom teaching can be measured separately in two scales. Students values on the scale representing a preference for online learning correlate positively and significantly with confidence in the choice of the study subject, enthusiasm about the subject, and the ability to organize their learning, learning environment, and time management. They correlate also with the satisfaction concerning the materials provided. Students values for one of those teaching methods also correlate with their rating with regard to their exam preparation. Values representing a preference for online teaching correlate positively with students better feeling of exam preparation. Values representing a preference for classroom teaching show negative correlations with the values representing students similar or even better preparation for the exams as a result of online teaching. It is therefore not surprising that the ratings for the two scales correlate with the wish for a combination of online teaching and classroom teaching in the future. As a solution, a new course concept for the time after the corona virus crisis that suits all students is outlined in the outlook.}, language = {en} } @article{KielarXinXuetal.2019, author = {Kielar, Charlotte and Xin, Yang and Xu, Xiaodan and Zhu, Siqi and Gorin, Nelli and Grundmeier, Guido and M{\"o}ser, Christin and Smith, David M. and Keller, Adrian}, title = {Effect of staple age on DNA origami nanostructure assembly and stability}, series = {Molecules}, volume = {24}, journal = {Molecules}, number = {14}, publisher = {MDPI}, address = {Basel}, issn = {1420-3049}, doi = {10.3390/molecules24142577}, pages = {12}, year = {2019}, abstract = {DNA origami nanostructures are widely employed in various areas of fundamental and applied research. Due to the tremendous success of the DNA origami technique in the academic field, considerable efforts currently aim at the translation of this technology from a laboratory setting to real-world applications, such as nanoelectronics, drug delivery, and biosensing. While many of these real-world applications rely on an intact DNA origami shape, they often also subject the DNA origami nanostructures to rather harsh and potentially damaging environmental and processing conditions. Furthermore, in the context of DNA origami mass production, the long-term storage of DNA origami nanostructures or their pre-assembled components also becomes an issue of high relevance, especially regarding the possible negative effects on DNA origami structural integrity. Thus, we investigated the effect of staple age on the self-assembly and stability of DNA origami nanostructures using atomic force microscopy. Different harsh processing conditions were simulated by applying different sample preparation protocols. Our results show that staple solutions may be stored at -20 degrees C for several years without impeding DNA origami self-assembly. Depending on DNA origami shape and superstructure, however, staple age may have negative effects on DNA origami stability under harsh treatment conditions. Mass spectrometry analysis of the aged staple mixtures revealed no signs of staple fragmentation. We, therefore, attribute the increased DNA origami sensitivity toward environmental conditions to an accumulation of damaged nucleobases, which undergo weaker base-pairing interactions and thus lead to reduced duplex stability.}, language = {en} }