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Item type:Item, Uncovering obstacles and limitations of smartness: a cross-case analysis of smart cities and smart real estate(2026-09-05) Al-Rimawi, Tarek; Nadler, MichaelSmart cities and smart real estate are increasingly used to enhance urban efficiency, sustainability, and quality of life. Nevertheless, their implementation is hindered by interconnected challenges across concepts, technology, governance, economics, society, ethics, and the environment. Thus, this paper examines how and why interconnected limitations constrain the smartness of smart city and smart real estate initiatives and identifies the governance and implementation responses revealed by cross-case comparison. The analysis of secondary academic sources, policy papers, standards, and industry reports compares Toronto, Songdo, NEOM, and Barcelona. The results identify six categories of limitations: conceptual and strategic; technological and infrastructural; governance and institutional; economic and financial; social and ethical; and environmental. The analysis shows that the challenges facing these initiatives go beyond technology alone and include ambiguous definitions of smartness, poor governance, limited public involvement, privacy and surveillance risks, high implementation and maintenance costs, interoperability issues, and unverified assumptions that technological advancement will deliver sustainability. The comparison of cases highlights that the success of these initiatives depends on effective governance, responsible data management, public trust, financial feasibility, institutional coordination, and a life cycle approach. The study concludes that smartness should be understood as an integrated institutional, economic, social, technological, and environmental capacity rather than as the mere adoption of digital technologies.Item type:Item, Quantum beats of exciton-polarons in CsPbI₃ perovskite nanocrystals(2026-05-26) Trifonov, Artur V.; Nestoklon, Mikhail O.; Hollberg, M. Alex; Grisard, Stefan; Kudlacik, Dennis; Kolobkova, Elena V.; Kuznetsova, Maria S.; Goupalov, Serguei V.; Kaspari, Jan M.; Reiter, Doris E.; Yakovlev, Dmitri R.; Bayer, Manfred; Akimov, Ilya A.The optical response of semiconductors is governed by coupled electronic and vibrational excitations. In lead-halide perovskite nanocrystals, strong exciton–phonon interaction forms a ladder of exciton-polaron states accessible by femtosecond laser pulses. We demonstrate a fully coherent regime of exciton-polaron dynamics with long optical coherence times (T₂ ≈ 300 ps) in CsPbI₃ nanocrystals embedded in glass. Using transient two-pulse photon echo at a temperature of 2 K, we observe quantum beats between exciton-polaron states, with decay determined by optical phonon lifetimes of 5-15 ps. Within a four-level model, we directly quantify the exciton–phonon coupling strength through Huang–Rhys factors of 0.05 − 0.12 and 0.02 − 0.04 for low-energy optical phonons with energies of 3.2 and 5.1 meV, respectively. The pronounced size dependence of both coupling strengths and phonon lifetimes offers a route to tune the optical transitions between exciton-polaron states and tailor the coherent optical dynamics in perovskite semiconductors for solid-state quantum technologies.Item type:Item, Amtliche Mitteilungen der Technischen Universität Dortmund Nr. 21/2026(Technische Universität Dortmund, 2026-10-01)Item type:Item, Molecular thermodynamics of complex coacervate systems. Part II: Measuring and modeling of the phase envelope using pePC-SAFT(Elsevier BV, 2024-12-05) Ascani, Moreno; Lipínski, Wojciech P.; Smokers, Iris B.A.; Neethirajah, Piramsuya; Vogel, Max; Spruijt, Evan; Sadowski, Gabriele; Held, ChristophComplex coacervation is an associative liquid-liquid phase separation (LLPS) observed in aqueous solutions of oppositely charged polyions. Coacervates are relevant systems in biology, chemistry, food and cosmetics industry, medicine as well as in engineering e.g. as extracting agents, for drug delivery or as gelling, foaming or stabilizing agents. Unfortunately, accurate experimental data on equilibrium compositions of complex coacervates are still scarce in the literature. Here, the LLPS of the coacervate-forming system water-Na₂NADH-protamine sulfate was measured at T = 298.15 K and p = 1.013 bar and at different polycation/polyanion ratios. Qualitative features of the experimental phase envelope are carefully discussed based on molecular interactions in this system. Compared to equilibrium data of the system water-Na₂NADH-poly-l-lysine HBr, the system water-Na₂NADH-protamine sulfate revealed a larger miscibility gap, suggesting a strong contribution of non-coulombic interactions to the phase behavior of this coacervate system. Experimental data were successfully modeled using the recently developed pePC-SAFT (Ascani et al., Part 1, Fluid Phase Equilibria, under review). The pePC-SAFT predicted phase envelope was in very good agreement with the measured experimental points. To the best of our knowledge, this is the first time that a physically sound model was used to model the phase envelope of a biologically relevant complex coacervate system.Item type:Item, Minimum degree conditions for containing an r-regular r-connected spanning subgraph(2024-02-26) Hahn-Klimroth, Max; Parczyk, Olaf; Person, YuryWe study optimal minimum degree conditions when an n-vertex graph G contains an r-regular r-connected spanning subgraph. We prove for r fixed and n large the condition to be δ(G)≥(n+r−2)/2 when nr≡0 (mod 2). This answers a question of M. Kriesell.