@article{DasElTawargyKhechineetal.2019, author = {Das, Abhijna and El-Tawargy, Ahmed S. and Khechine, Emna and Noack, Sebastian and Schlaad, Helmut and Reiter, G{\"u}nter and Reiter, Renate}, title = {Controlling Nucleation in Quasi-Two-Dimensional Langmuir Poly(L-lactide) Films through Variation of the Rate of Compression}, series = {Langmuir}, volume = {35}, journal = {Langmuir}, number = {18}, publisher = {American Chemical Society}, address = {Washington}, issn = {0743-7463}, doi = {10.1021/acs.langmuir.9b00619}, pages = {6129 -- 6136}, year = {2019}, abstract = {We studied morphological changes in a quasi-two-dimensional Langmuir film of low molar mass poly(L-lactide) upon increasing the surface density, starting from randomly distributed molecules to a homogeneous monolayer of closely packed molecules, followed by nucleation and growth of mesoscopic, three-dimensional clusters from an overcompressed monolayer. The corresponding nucleation density of mesoscopic clusters within the monolayer can be tailored through variation of the rate of compression. For a given surface density and temperature, the nucleation probability was found to increase linearly with the rate of compression, allowing to adjust the density of mesoscopic clusters over nearly 2 orders magnitude.}, language = {en} } @article{DasNoackSchlaadetal.2020, author = {Das, Abhijna and Noack, Sebastian and Schlaad, Helmut and Reiter, G{\"u}nter and Reiter, Renate}, title = {Exploring pathways to equilibrate Langmuir polymer films}, series = {Langmuir}, volume = {36}, journal = {Langmuir}, number = {28}, publisher = {American Chemical Society}, address = {Washington}, issn = {0743-7463}, doi = {10.1021/acs.langmuir.0c01268}, pages = {8184 -- 8192}, year = {2020}, abstract = {Focusing on the phase-coexistence region in Langmuir films of poly(L-lactide), we investigated changes in nonequilibrated morphologies and the corresponding features of the isotherms induced by different experimental pathways of lateral compression and expansion. In this coexistence region, the surface pressure II was larger than the expected equilibrium value and was found to increase upon compression, i.e., exhibited a nonhorizontal plateau. As shown earlier by using microscopic techniques [Langmuir 2019, 35, 6129-6136], in this plateau region, well-ordered mesoscopic clusters coexisted with a surrounding matrix phase. We succeeded in reducing Pi either by slowing down the rate of compression or through increasing the waiting time after stopping the movement of the barriers, which allowed for relaxations in the coexistence region. Intriguingly, the most significant pressure reduction was observed when recompressing a film that had already been compressed and expanded, if the recompression was started from an area value smaller than the one anticipated for the onset of the coexistence region. This observation suggests a "self-seeding" behavior, i.e., pre-existing nuclei allowed to circumvent the nucleation step. The decrease in Pi was accompanied by a transformation of the initially formed metastable mesoscopic clusters into a thermodynamically favored filamentary morphology. Our results demonstrate that it is practically impossible to obtain fully equilibrated coexisting phases in a Langmuir polymer film, neither under conditions of extremely slow continuous compression nor for long waiting times at a constant area in the coexistence region which allow for reorganization.}, language = {en} } @article{ChandranDoldBuvignieretal.2015, author = {Chandran, Sivasurender and Dold, Stefanie and Buvignier, Amaury and Krannig, Kai-Steffen and Schlaad, Helmut and Reiter, G{\"u}nter and Reiter, Renate}, title = {Tuning Morphologies of Langmuir Polymer Films Through Controlled Relaxations of Non-Equilibrium States}, series = {Langmuir}, volume = {31}, journal = {Langmuir}, number = {23}, publisher = {American Chemical Society}, address = {Washington}, issn = {0743-7463}, doi = {10.1021/acs.langmuir.5b01212}, pages = {6426 -- 6435}, year = {2015}, abstract = {Langmuir polymers films (LPFs) frequently form non-equilibrium states which are manifested in a decay of the surface pressure with time when the system is allowed to relax. Monitoring and manipulating the temporal evolution of these relaxations experimentally helps to shed light on the associated molecular reorganization processes. We present a systematic study based on different compression protocols and show how these reorganization processes impact the morphology of LPFs of poly(gamma-benzyl-L-glutamate) (PBLG); visualized by means of atomic force microscopy. Upon continuous compression, a fibrillar morphology was formed with a surface decorated by squeezed-out islands. By contrast, stepwise compression promoted the formation of a fibrillar network with a bimodal distribution of fibril diameters, caused by merging of fibrils. Finally, isobaric compression induced in-plane compaction of the monolayer. We correlate these morphological observations with the kinetics of the corresponding relaxations, described best by a sum of two exponential functions with different time scales representing two molecular processes. We discuss the observed kinetics and the resulting morphologies in the context of nucleation and growth, characteristic for first-order phase transitions. Our results demonstrate that the preparation conditions of LPFs have tremendous impact on ordering of the molecules and hence various macroscopic properties of such films.}, language = {en} } @article{KnechtReiterSchlaadetal.2017, author = {Knecht, Volker and Reiter, Guenter and Schlaad, Helmut and Reiter, Renate}, title = {Structure Formation in Langmuir Peptide Films As Revealed from Coarse-Grained Molecular Dynamics Simulations}, series = {Langmuir}, volume = {33}, journal = {Langmuir}, publisher = {American Chemical Society}, address = {Washington}, issn = {0743-7463}, doi = {10.1021/acs.langmuir.7b01455}, pages = {6492 -- 6502}, year = {2017}, abstract = {Molecular dynamics simulations in conjunction with the Martini coarse-grained model have been used to investigate the (nonequilibrium) behavior of helical 22-residue poly(gamma-benzyl-L-glutamate) (PBLG) peptides at the water/vapor interface. Preformed PBLG mono- or bilayers homogeneously covering the water surface laterally collapse in tens of nanoseconds, exposing significant proportions of empty water surface. This behavior was also observed in recent AFM experiments at similar areas per monomer, where a complete coverage had been assumed in earlier work. In the simulations, depending on the area per monomer, either elongated clusters or fibrils form, whose heights (together with the portion of empty water surface) increase over time. Peptides tend to align with respect to the fiber axis or with the major principal axis of the cluster, respectively. The aspect ratio of the cluster observed is 1.7 and, hence, comparable to though somewhat smaller than the aspect ratio of the peptides in alpha-helical conformation, which is 2.2. The heights of the fibrils is 3 nm after 20 ns and increases to 4.5 nm if the relaxation time is increased by 2 orders of magnitude, in agreement with the experiment. Aggregates with heights of about 3 or 4.5 nm are found to correspond to local bi- or trilayer structures, respectively.}, language = {en} } @article{KuhlmannHellstroemRambergetal.2021, author = {Kuhlmann, Sabine and Hellstr{\"o}m, Mikael and Ramberg, Ulf and Reiter, Renate}, title = {Tracing divergence in crisis governance}, series = {International review of administrative sciences}, volume = {87}, journal = {International review of administrative sciences}, number = {3}, publisher = {Sage}, address = {Los Angeles, California}, issn = {0020-8523}, doi = {10.1177/0020852320979359}, pages = {556 -- 575}, year = {2021}, abstract = {This cross-country comparison of administrative responses to the COVID-19 pandemic in France, Germany and Sweden is aimed at exploring how institutional contexts and administrative cultures have shaped strategies of problem-solving and governance modes during the pandemic, and to what extent the crisis has been used for opportunity management. The article shows that in France, the central government reacted determinedly and hierarchically, with tough containment measures. By contrast, the response in Germany was characterized by an initial bottom-up approach that gave way to remarkable federal unity in the further course of the crisis, followed again by a return to regional variance and local discretion. In Sweden, there was a continuation of 'normal governance' and a strategy of relying on voluntary compliance largely based on recommendations and less - as in Germany and France - on a strategy of imposing legally binding regulations. The comparative analysis also reveals that relevant stakeholders in all three countries have used the crisis as an opportunity for changes in the institutional settings and administrative procedures.}, language = {en} } @article{KuhlmannBouckaertGallietal.2021, author = {Kuhlmann, Sabine and Bouckaert, Geert and Galli, Davide and Reiter, Renate and van Hecke, Steven}, title = {Opportunity management of the COVID-19 pandemic}, series = {International review of administrative sciences}, volume = {87}, journal = {International review of administrative sciences}, number = {3}, publisher = {Sage}, address = {Los Angeles, California}, issn = {0020-8523}, doi = {10.1177/0020852321992102}, pages = {497 -- 517}, year = {2021}, abstract = {This article provides a conceptual framework for the analysis of COVID-19 crisis governance in the first half of 2020 from a cross-country comparative perspective. It focuses on the issue of opportunity management, that is, how the crisis was used by relevant actors of distinctly different administrative cultures as a window of opportunity. We started from an overall interest in the factors that have influenced the national politics of crisis management to answer the question of whether and how political and administrative actors in various countries have used the crisis as an opportunity to facilitate, accelerate or prevent changes in institutional settings. The objective is to study the institutional settings and governance structures, (alleged) solutions and remedies, and constellations of actors and preferences that have influenced the mode of crisis and opportunity management. Finally, the article summarizes some major comparative findings drawn from the country studies of this Special Issue, focusing on similarities and differences in crisis responses and patterns of opportunity management.}, language = {en} } @article{BouckaertGalliKuhlmannetal.2020, author = {Bouckaert, Geert and Galli, Davide and Kuhlmann, Sabine and Reiter, Renate and van Hecke, Steven}, title = {European coronationalism?}, series = {Public administration review}, volume = {80}, journal = {Public administration review}, number = {5}, publisher = {Wiley-Blackwell}, address = {Oxford}, issn = {0033-3352}, doi = {10.1111/puar.13242}, pages = {765 -- 773}, year = {2020}, abstract = {The COVID-19 crisis has shown that European countries remain poorly prepared for dealing and coping with health crises and for responding in a coordinated way to a severe influenza pandemic. Within the European Union, the response to the COVID-19 pandemic has a striking diversity in its approach. By focusing on Belgium, France, Germany, and Italy—countries that represent different models of administrative systems in Europe—the analysis shows that major similarities and convergences have become apparent from a cross-country perspective. Moreover, coping with the crisis has been first and foremost an issue of the national states, whereas the European voice has been weak. Hence, the countries' immediate responses appear to be corona-nationalistic, which we label "coronationalism." This essay shows the extent to which the four countries adopted different crisis management strategies and which factors explain this variance, with a special focus on their institutional settings and administrative systems.}, language = {en} } @article{KuhlmannReiter2016, author = {Kuhlmann, Sabine and Reiter, Renate}, title = {Decentralization of the French welfare state: from 'big bang' to 'muddling through'}, series = {International Review of Administrative Sciences}, volume = {82}, journal = {International Review of Administrative Sciences}, number = {2}, publisher = {Sage}, address = {London}, issn = {0020-8523}, doi = {0.1177/0020852315583194}, pages = {255 -- 272}, year = {2016}, abstract = {This article analyses the decentralization of the French welfare state focusing on the transfer of the Revenu minimum d'insertion (RMI) welfare benefit to the departments in 2003 and 2004. We map and explain the effects of the reform on the system and performance of the subnational provision of welfare tasks. To evaluate the impact of decentralization on the RMI-related action of the departments, we carry out a qualitative document analysis and use data from two case studies. The RMI decentralization offers an exemplary insight into the incremental implementation of French decentralization. We find many unintended effects in terms of the performance and outcome of the subnational welfare provision. This is traced back to the combining of institutional and policy reforms and the inadequate translation of high political expectations into an inadequate action programme both resulting in excessive demands on the local actors. Points for practitioners The decentralization of public tasks is associated with high expectations in terms of the effects on the performance of public services and public governance on the subnational levels. For an in-depth measure the range of administrative performance and political systems effects should be taken into account. We propose a five-dimensional scheme allowing for the determination of decentralization effects on the resource input to and the operative output of subnational public services, on the horizontal coordination between subnational task holders and the affected non-public stakeholders, on the vertical intergovernmental coordination, and on the democratic accountability of subnational authorities.}, language = {en} }