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End date: 2023 × Start date: 2023 × Start date: 2020 × Version: publishedVersion × WGL Institute: MBI ×

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Now showing 1 - 10 of 30
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    Short-Range Cooperative Slow-down of Water Solvation Dynamics Around SO42--Mg2+ Ion Pairs
    (Washington, DC : American Chemical Society, 2022) Kundu, Achintya; Mamatkulov, Shavkat I.; Brünig, Florian N.; Bonthuis, Douwe Jan; Netz, Roland R.; Elsaesser, Thomas; Fingerhut, Benjamin P.
    The presence of ions affects the structure and dynamics of water on a multitude of length and time scales. In this context, pairs of Mg2+ and SO42- ions in water constitute a prototypical system for which conflicting pictures of hydration geometries and dynamics have been reported. Key issues are the molecular pair and solvation shell geometries, the spatial range of electric interactions, and their impact on solvation dynamics. Here, we introduce asymmetric SO42- stretching vibrations as new and most specific local probes of solvation dynamics that allow to access ion hydration dynamics at the dilute concentration (0.2 M) of a native electrolyte environment. Highly sensitive heterodyne 2D-IR spectroscopy in the fingerprint region of the SO42- ions around 1100 cm-1 reveals a specific slow-down of solvation dynamics for hydrated MgSO4 and for Na2SO4 in the presence of Mg2+ ions, which manifests as a retardation of spectral diffusion compared to aqueous Na2SO4 solutions in the absence of Mg2+ ions. Extensive molecular dynamics and density functional theory QM/MM simulations provide a microscopic view of the observed ultrafast dephasing and hydration dynamics. They suggest a molecular picture where the slow-down of hydration dynamics arises from the structural peculiarities of solvent-shared SO42--Mg2+ ion pairs.
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    Transient spin injection efficiencies at ferromagnet/metal interfaces
    (Weinheim : Wiley-VCH, 2022-10-19) Elliott, Peter; Eschenlohr, Andrea; Chen, Jinghao; Shallcross, Sam; Bovensiepen, Uwe; Dewhurst, John Kay; Sharma, Sangeeta
    Spin injection across interfaces driven by ultrashort optical pulses on femtosecond timescales constitutes a new way to design spintronics applications. Targeted utilization of this phenomenon requires knowledge of the efficiency of non-equilibrium spin injection. From a quantitative comparison of ab initio time-dependent density functional theory and interface-sensitive, time-resolved non-linear optical experiment, the spin injection efficiency (SIE) at the Co/Cu(001) interface is determined, and its microscopic origin, i.e., the influence of spin-orbit coupling and the interface electronic structure, is discussed. Moreover, we theoretically predict that the SIE at ferromagnetic–metal interfaces can be optimized through laser pulse and materials parameters, namely the fluence, pulse duration, and substrate material.
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    Zwitterionic Dendrimersomes: A Closer Xenobiotic Mimic of Cell Membranes
    (Weinheim : Wiley-VCH, 2022-10-31) Joseph, Anton; Wagner, Anna M.; Garay-Sarmiento, Manuela; Aleksanyan, Mina; Haraszti, Tamás; Söder, Dominik; Georgiev, Vasil N.; Dimova, Rumiana; Percec, Virgil; Rodriguez-Emmenegger, Cesar
    Building functional mimics of cell membranes is an important task toward the development of synthetic cells. So far, lipid and amphiphilic block copolymers are the most widely used amphiphiles with the bilayers by the former lacking stability while membranes by the latter are typically characterized by very slow dynamics. Herein, a new type of Janus dendrimer containing a zwitterionic phosphocholine hydrophilic headgroup (JDPC) and a 3,5-substituted dihydrobenzoate-based hydrophobic dendron is introduced. JDPC self-assembles in water into zwitterionic dendrimersomes (z-DSs) that faithfully recapitulate the cell membrane in thickness, flexibility, and fluidity, while being resilient to harsh conditions and displaying faster pore closing dynamics in the event of membrane rupture. This enables the fabrication of hybrid DSs with components of natural membranes, including pore-forming peptides, structure-directing lipids, and glycans to create raft-like domains or onion vesicles. Moreover, z-DSs can be used to create active synthetic cells with life-like features that mimic vesicle fusion and motility as well as environmental sensing. Despite their fully synthetic nature, z-DSs are minimal cell mimics that can integrate and interact with living matter with the programmability to imitate life-like features and beyond.
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    Supramolecular organization as a factor of ribonuclease cytotoxicity
    (Moscow : Park Media, 2020) Dudkina, Elena V.; Ulyanova, Vera V.; Ilinskaya, Olga N.
    One of the approaches used to eliminate tumor cells is directed destruction/modification of their RNA molecules. In this regard, ribonucleases (RNases) possess a therapeutic potential that remains largely unexplored. It is believed that the biological effects of secreted RNases, namely their antitumor and antiviral properties, derive from their catalytic activity. However, a number of recent studies have challenged the notion that the activity of RNases in the manifestation of selective cytotoxicity towards cancer cells is exclusively an enzymatic one. In this review, we have analyzed available data on the cytotoxic effects of secreted RNases, which are not associated with their catalytic activity, and we have provided evidence that the most important factor in the selective apoptosis-inducing action of RNases is the structural organization of these enzymes, which determines how they interact with cell components. The new idea on the preponderant role of non-catalytic interactions between RNases and cancer cells in the manifestation of selective cytotoxicity will contribute to the development of antitumor RNase-based drugs.
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    Sonopharmacology: controlling pharmacotherapy and diagnosis by ultrasound-induced polymer mechanochemistry
    (Cambridge : RSC, 2022) Yildiz, Deniz; Göstl, Robert; Herrmann, Andreas
    Active pharmaceutical ingredients are the most consequential and widely employed treatment in medicine although they suffer from many systematic limitations, particularly off-target activity and toxicity. To mitigate these effects, stimuli-responsive controlled delivery and release strategies for drugs are being developed. Fueled by the field of polymer mechanochemistry, recently new molecular technologies enabled the emergence of force as an unprecedented stimulus for this purpose by using ultrasound. In this research area, termed sonopharmacology, mechanophores bearing drug molecules are incorporated within biocompatible macromolecular scaffolds as preprogrammed, latent moieties. This review presents the novelties in controlling drug activation, monitoring, and release by ultrasound, while discussing the limitations and challenges for future developments.
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    A general approach for all-visible-light switching of diarylethenes through triplet sensitization using semiconducting nanocrystals
    (London [u.a.] : RSC, 2022) Hou, Lili; Larsson, Wera; Hecht, Stefan; Andréasson, Joakim; Albinsson, Bo
    Coupling semiconducting nanocrystals (NCs) with organic molecules provides an efficient route to generate and transfer triplet excitons. These excitons can be used to power photochemical transformations such as photoisomerization reactions using low energy radiation. Thus, it is desirable to develop a general approach that can efficiently be used to control photoswitches using all-visible-light aiming at future applications in life- and materials sciences. Here, we demonstrate a simple ‘cocktail’ strategy that can achieve all-visible-light switchable diarylethenes (DAEs) through triplet energy transfer from the hybrid of CdS NCs and phenanthrene-3-carboxylic acid, with high photoisomerization efficiency and improved fatigue resistance. The size-tunable excitation energies of CdS NCs make it possible to precisely match the clear spectral window of the relevant DAE photoswitch. We demonstrate reversible all-visible-light photoisomerization of a series of DAE derivatives both in the liquid and solid state, even in the presence of oxygen. Our general strategy is promising for fabrication of all-visible-light activated optoelectronic devices as well as memories, and should in principle be adaptable to photopharmacology.
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    General Time-Dependent Configuration-Interaction Singles II: The Atomic Case
    (Woodbury, NY : Inst., 2022-10-10) Carlström, Stefanos; Bertolino, Mattias; Dahlström, Jan Marcus; Patchkovskii, Serguei
    We present a specialization of the grid-based implementation of the time-dependent configuration-interaction singles described in the preceding paper [S. Carlström et al., preceding paper, Phys. Rev. A 106, 043104 (2022)]. to the case of spherical symmetry. We describe the intricate time propagator in detail and conclude with a few example calculations. Among these, of note are high-resolution photoelectron spectra in the vicinity of the Fano resonances in photoionization of neon and spin-polarized photoelectrons from xenon, in agreement with recent experiments.
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    General Time-Dependent Configuration-Interaction Singles I: The Molecular Case
    (Woodbury, NY : Inst., 2022-10-10) Carlström, Stefanos; Spanner, Michael; Patchkovskii, Serguei
    We present a grid-based implementation of the time-dependent configuration-interaction singles method suitable for computing the strong-field ionization of small gas-phase molecules. After outlining the general equations of motion used in our treatment of this method, we present example calculations of strong-field ionization of He, LiH, H2O, and C2H4 that demonstrate the utility of our implementation. The following paper [S. Carlström et al., following paper, Phys. Rev. A 106, 042806 (2022)] specializes to the case of spherical symmetry, which is applied to various atoms.
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    Coherent control of the photoinduced transition in a strongly correlated material
    (College Park, MD : APS, 2022) Molinero, Eduardo B.; Silva, Rui E. F.
    The use of intense tailored light fields is the perfect tool to achieve ultrafast control of electronic properties in quantum materials. Among them, Mott insulators are materials in which strong electron-electron interactions drive the material into an insulating phase. When shining a Mott insulator with a strong laser pulse, the electric field may induce the creation of doublon-hole pairs, triggering a photoinduced transition into a metallic state. In this paper, we take advantage of the threshold character of this photoinduced transition and we propose a setup that consists of a midinfrared laser pulse and a train of short pulses separated by a half period of the midinfrared with alternating phases. By varying the time delay between the two pulses and the internal carrier envelope phase of the short pulses, we achieve control of the phase transition, which leaves its fingerprint at its high harmonic spectrum.
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    The 2022 magneto-optics roadmap
    (Bristol : IOP Publ., 2022-09-28) Kimel, Alexey; Zvezdin, Anatoly; Sharma, Sangeeta; Shallcross, Samuel; de Sousa, Nuno; García-Martín, Antonio; Salvan, Georgeta; Hamrle, Jaroslav; Stejskal, Ondřej; McCord, Jeffrey; Tacchi, Silvia; Carlotti, Giovanni; Gambardella, Pietro; Salis, Gian; Münzenberg, Markus; Schultze, Martin; Temnov, Vasily; Bychkov, Igor V.; Kotov, Leonid N.; Maccaferri, Nicolò; Ignatyeva, Daria; Belotelov, Vladimir; Donnelly, Claire; Rodriguez, Aurelio Hierro; Matsuda, Iwao; Ruchon, Thierry; Fanciulli, Mauro; Sacchi, Maurizio; Du, Chunhui Rita; Wang, Hailong; Armitage, N. Peter; Schubert, Mathias; Darakchieva, Vanya; Liu, Bilu; Huang, Ziyang; Ding, Baofu; Berger, Andreas; Vavassori, Paolo
    Magneto-optical (MO) effects, viz. magnetically induced changes in light intensity or polarization upon reflection from or transmission through a magnetic sample, were discovered over a century and a half ago. Initially they played a crucially relevant role in unveiling the fundamentals of electromagnetism and quantum mechanics. A more broad-based relevance and wide-spread use of MO methods, however, remained quite limited until the 1960s due to a lack of suitable, reliable and easy-to-operate light sources. The advent of Laser technology and the availability of other novel light sources led to an enormous expansion of MO measurement techniques and applications that continues to this day (see section 1). The here-assembled roadmap article is intended to provide a meaningful survey over many of the most relevant recent developments, advances, and emerging research directions in a rather condensed form, so that readers can easily access a significant overview about this very dynamic research field. While light source technology and other experimental developments were crucial in the establishment of today's magneto-optics, progress also relies on an ever-increasing theoretical understanding of MO effects from a quantum mechanical perspective (see section 2), as well as using electromagnetic theory and modelling approaches (see section 3) to enable quantitatively reliable predictions for ever more complex materials, metamaterials, and device geometries. The latest advances in established MO methodologies and especially the utilization of the MO Kerr effect (MOKE) are presented in sections 4 (MOKE spectroscopy), 5 (higher order MOKE effects), 6 (MOKE microscopy), 8 (high sensitivity MOKE), 9 (generalized MO ellipsometry), and 20 (Cotton–Mouton effect in two-dimensional materials). In addition, MO effects are now being investigated and utilized in spectral ranges, to which they originally seemed completely foreign, as those of synchrotron radiation x-rays (see section 14 on three-dimensional magnetic characterization and section 16 on light beams carrying orbital angular momentum) and, very recently, the terahertz (THz) regime (see section 18 on THz MOKE and section 19 on THz ellipsometry for electron paramagnetic resonance detection). Magneto-optics also demonstrates its strength in a unique way when combined with femtosecond laser pulses (see section 10 on ultrafast MOKE and section 15 on magneto-optics using x-ray free electron lasers), facilitating the very active field of time-resolved MO spectroscopy that enables investigations of phenomena like spin relaxation of non-equilibrium photoexcited carriers, transient modifications of ferromagnetic order, and photo-induced dynamic phase transitions, to name a few. Recent progress in nanoscience and nanotechnology, which is intimately linked to the achieved impressive ability to reliably fabricate materials and functional structures at the nanoscale, now enables the exploitation of strongly enhanced MO effects induced by light–matter interaction at the nanoscale (see section 12 on magnetoplasmonics and section 13 on MO metasurfaces). MO effects are also at the very heart of powerful magnetic characterization techniques like Brillouin light scattering and time-resolved pump-probe measurements for the study of spin waves (see section 7), their interactions with acoustic waves (see section 11), and ultra-sensitive magnetic field sensing applications based on nitrogen-vacancy centres in diamond (see section 17). Despite our best attempt to represent the field of magneto-optics accurately and do justice to all its novel developments and its diversity, the research area is so extensive and active that there remains great latitude in deciding what to include in an article of this sort, which in turn means that some areas might not be adequately represented here. However, we feel that the 20 sections that form this 2022 magneto-optics roadmap article, each written by experts in the field and addressing a specific subject on only two pages, provide an accurate snapshot of where this research field stands today. Correspondingly, it should act as a valuable reference point and guideline for emerging research directions in modern magneto-optics, as well as illustrate the directions this research field might take in the foreseeable future.