| 11. |
- Tatsuno, Hideyuki, et al.
(author)
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Hot Branching Dynamics in a Light-Harvesting Iron Carbene Complex Revealed by Ultrafast X-ray Emission Spectroscopy
- 2020
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In: Angewandte Chemie - International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 59:1, s. 364-372
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Journal article (peer-reviewed)abstract
- Iron N-heterocyclic carbene (NHC) complexes have received a great deal of attention recently because of their growing potential as light sensitizers or photocatalysts. We present a sub-ps X-ray spectroscopy study of an FeIINHC complex that identifies and quantifies the states involved in the deactivation cascade after light absorption. Excited molecules relax back to the ground state along two pathways: After population of a hot 3MLCT state, from the initially excited 1MLCT state, 30 % of the molecules undergo ultrafast (150 fs) relaxation to the 3MC state, in competition with vibrational relaxation and cooling to the relaxed 3MLCT state. The relaxed 3MLCT state then decays much more slowly (7.6 ps) to the 3MC state. The 3MC state is rapidly (2.2 ps) deactivated to the ground state. The 5MC state is not involved in the deactivation pathway. The ultrafast partial deactivation of the 3MLCT state constitutes a loss channel from the point of view of photochemical efficiency and highlights the necessity to screen transition-metal complexes for similar ultrafast decays to optimize photochemical performance.
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| 12. |
- Vester, Peter, et al.
(author)
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Tracking structural solvent reorganization and recombination dynamics following e-photoabstraction from aqueous I-with femtosecond x-ray spectroscopy and scattering
- 2022
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In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 157:22
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Journal article (peer-reviewed)abstract
- We present a sub-picosecond resolved investigation of the structural solvent reorganization and geminate recombination dynamics following 400 nm two-photon excitation and photodetachment of a valence p electron from the aqueous atomic solute, I-(aq). The measurements utilized time-resolved X-ray Absorption Near Edge Structure (TR-XANES) spectroscopy and X-ray Solution Scattering (TR-XSS) at the Linac Coherent Light Source x-ray free electron laser in a laser pump/x-ray probe experiment. The XANES measurements around the L1-edge of the generated nascent iodine atoms (I0) yield an average electron ejection distance from the iodine parent of 7.4 ± 1.5 Å with an excitation yield of about 1/3 of the 0.1M NaI aqueous solution. The kinetic traces of the XANES measurement are in agreement with a purely diffusion-driven geminate iodine-electron recombination model without the need for a long-lived (I0:e-) contact pair. Nonequilibrium classical molecular dynamics simulations indicate a delayed response of the caging H2O solvent shell and this is supported by the structural analysis of the XSS data: We identify a two-step process exhibiting a 0.1 ps delayed solvent shell reorganization time within the tight H-bond network and a 0.3 ps time constant for the mean iodine-oxygen distance changes. The results indicate that most of the reorganization can be explained classically by a transition from a hydrophilic cavity with a well-ordered first solvation shell (hydrogens pointing toward I-) to an expanded cavity around I0 with a more random orientation of the H2O molecules in a broadened first solvation shell.
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| 13. |
- von Thiele Schwarz, Ulrica, 1975-, et al.
(author)
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How to design, implement and evaluate organizational interventions for maximum impact : the Sigtuna Principles
- 2021
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In: European Journal of Work and Organizational Psychology. - Abingdon : Routledge. - 1359-432X .- 1464-0643. ; 30:3, s. 415-427
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Journal article (peer-reviewed)abstract
- Research on organizational interventions needs to meet the objectives of both researchers and participating organizations. This duality means that real-world impact has to be considered throughout the research process, simultaneously addressing both scientific rigour and practical relevance. This discussion paper aims to offer a set of principles, grounded in knowledge from various disciplines that can guide researchers in designing, implementing, and evaluating organizational interventions. Inspired by Mode 2 knowledge production, the principles were developed through a transdisciplinary, participatory and iterative process where practitioners and academics were invited to develop, refine and validate the principles. The process resulted in 10 principles: 1) Ensure active engagement and participation among key stakeholders; 2) Understand the situation (starting points and objectives); 3) Align the intervention with existing organizational objectives; 4) Explicate the program logic; 5) Prioritize intervention activities based on effort-gain balance; 6) Work with existing practices, processes, and mindsets; 7) Iteratively observe, reflect, and adapt; 8) Develop organizational learning capabilities; 9) Evaluate the interaction between intervention, process, and context; and 10) Transfer knowledge beyond the specific organization. The principles suggest how the design, implementation, and evaluation of organizational interventions can be researched in a way that maximizes both practical and scientific impact. © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
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| 14. |
- Wan, Feng, et al.
(author)
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Ultrasmall TPGS-PLGA Hybrid Nanoparticles for Site-Specific Delivery of Antibiotics into Pseudomonas aeruginosa Biofilms in Lungs
- 2020
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In: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 12:1, s. 380-389
-
Journal article (peer-reviewed)abstract
- Inhaled antibiotic treatment of cystic fibrosis-related bacterial biofilm infections is challenging because of the pathological environment of the lungs. Here, we present an "environment-adaptive" nanoparticle composed of a solid poly lactic-co-glycolic acid (PLGA) core and a mucus-inert, enzymatically cleavable shell of d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) for the site-specific delivery of antibiotics to bacterial biofilms via aerosol administration. The hybrid nanoparticles with ultrasmall size were self-assembled via a nanoprecipitation process by using a facile microfluidic method. The interactions of the nanoparticles with the biological barriers were comprehensively investigated by using cutting-edge techniques (e.g., quartz crystal microbalance with dissipation monitoring, total internal reflection fluorescence microscopy-based particle tracking, in vitro biofilm model cultured in a flow-chamber system, and quantitative imaging analysis). Our results suggest that the mucus-inert, enzymatically cleavable TPGS shell enables the nanoparticles to penetrate through the mucus, accumulate in the deeper layer of the biofilms, and serve as sustained release depot, thereby improving the killing efficacy of azithromycin (a macrolide antibiotic) against biofilm-forming Pseudomonas aeruginosa. In conclusion, the ultrasmall TPGS-PLGA hybrid nanoparticles represent an efficient delivery system to overcome the multiple barriers and release antibiotics in a sustained manner in the vicinity of the biofilm-forming bacteria.
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| 15. |
- Wang, Zhihang, 1989, et al.
(author)
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Liquid-Based Multijunction Molecular Solar Thermal Energy Collection Device
- 2021
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In: Advanced Science. - : Wiley. - 2198-3844 .- 2198-3844. ; 8:21
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Journal article (peer-reviewed)abstract
- Photoswitchable molecules-based solar thermal energy storage system (MOST) can potentially be a route to store solar energy for future use. Herein, the use of a multijunction MOST device that combines various photoswitches with different onsets of absorption to push the efficiency limit on solar energy collection and storage is explored. With a parametric model calculation, it is shown that the efficiency limit of MOST concept can be improved from 13.0% to 18.2% with a double-junction system and to 20.5% with a triple-junction system containing ideal, red-shifted MOST candidates. As a proof-of-concept, the use of a three-layered MOST device is experimentally demonstrated. The device uses different photoswitches including a norbornadiene derivative, a dihydroazulene derivative, and an azobenzene derivative in liquid state with different MOSTproperties, to increase the energy capture and storage behavior. This conceptional device introduces a new way of thinking and designing optimal molecular candidates for MOST, as much improvement can be made by tailoring molecules to efficiently store solar energy at specific wavelengths.
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| 16. |
- Wang, Zhihang, 1989, et al.
(author)
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Storing energy with molecular photoisomers
- 2021
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In: Joule. - : Elsevier BV. - 2542-4351. ; 5:12, s. 3116-3136
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Research review (peer-reviewed)abstract
- Some molecular photoisomers can be isomerized to a metastable high-energy state by exposure to light. These molecules can then be thermally or catalytically converted back to their initial state, releasing heat in the process. Such a reversible photochemical process has been considered for developing molecular solar thermal (MOST) systems. In this review, we introduce the concept, criteria, and state-of-the-art of MOST systems, with an emphasis on the three most promising molecular systems: norbornadiene/quadricyclane, E/Z-azobenzene, and dihydroazulene/vinylheptafulvene. After discussing the fundamental working principles, we focus on molecular design strategies for improving solar energy storage performance, remaining challenges, and potential focus areas. Finally, we summarize the current molecular incorporation into functional devices and conclude with a perspective on challenges and future directions.
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