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The water-splitting reaction using photocatalyst particles is a promising route for solar fuel production 1 – 4 . Photo-induced charge transfer from a photocatalyst to catalytic surface sites is key in ensuring photocatalytic efficiency 5 ; however, it is challenging to understand this process, which spans a wide spatiotemporal range from nanometres to micrometres and from femtoseconds to seconds 6 – 8 . Although the steady-state charge distribution on single photocatalyst particles has been mapped by microscopic techniques 9 – 11 , and the charge transfer dynamics in photocatalyst aggregations have been revealed by time-resolved spectroscopy 12 , 13 , spatiotemporally evolving charge transfer processes in single photocatalyst particles cannot be tracked, and their exact mechanism is unknown. Here we perform spatiotemporally resolved surface photovoltage measurements on cuprous oxide photocatalyst particles to map holistic charge transfer processes on the femtosecond to second timescale at the single-particle level. We find that photogenerated electrons are transferred to the catalytic surface quasi-ballistically through inter-facet hot electron transfer on a subpicosecond timescale, whereas photogenerated holes are transferred to a spatially separated surface and stabilized through selective trapping on a microsecond timescale. We demonstrate that these ultrafast-hot-electron-transfer and anisotropic-trapping regimes, which challenge the classical perception of a drift–diffusion model, contribute to the efficient charge separation in photocatalysis and improve photocatalytic performance. We anticipate that our findings will be used to illustrate the universality of other photoelectronic devices and facilitate the rational design of photocatalysts. Photovoltage measurements on cuprous oxide photocatalyst particles are used to spatiotemporally track the charge transfer processes on the femtosecond to second timescale at the single-particle level.

Quantum chaos is presented as a paradigm of information processing by dynamical systems at the bottom of the range of phase-space scales. Starting with a brief review of classical chaos as entropy flow from micro- to macro-scales, I argue that quantum chaos came as an indispensable rectification, removing inconsistencies related to entropy in classical chaos: bottom-up information currents require an inexhaustible entropy production and a diverging information density in phase-space, reminiscent of Gibbs’ paradox in statistical mechanics. It is shown how a mere discretization of the state space of classical models already entails phenomena similar to hallmarks of quantum chaos and how the unitary time evolution in a closed system directly implies the “quantum death” of classical chaos. As complementary evidence, I discuss quantum chaos under continuous measurement. Here, the two-way exchange of information with a macroscopic apparatus opens an inexhaustible source of entropy and lifts the limitations implied by unitary quantum dynamics in closed systems. The infiltration of fresh entropy restores permanent chaotic dynamics in observed quantum systems. Could other instances of stochasticity in quantum mechanics be interpreted in a similar guise? Where observed quantum systems generate randomness, could it result from an exchange of entropy with the macroscopic meter? This possibility is explored, presenting a model for spin measurement in a unitary setting and some preliminary analytical results based on it.

Charge separation is a critical process for achieving high photocatalytic efficiency, and ferroelectrics hold significant potential for facilitating effective charge separation. However, few studies have demonstrated substantial photocatalytic activity in these materials. In this study, we demonstrate that in ferroelectric PbTiO 3 , surface Ti vacancy defects near the positively polarized facets impede photocatalytic performance by trapping electrons and inducing their recombination. To tackle this issue, we selectively grew SrTiO 3 nanolayers on the polarized facets PbTiO 3 , effectively mitigating interface Ti defects. This modification establishes a efficient electron transfer pathway at the interface between the positively polarized facets and the cocatalyst, extending the electron lifetime from 50 microseconds to the millisecond scale and significantly increasing electron participation in water-splitting reactions. Consequently, the apparent quantum yield for overall water splitting achieves the highest values reported to date for ferroelectric photocatalytic materials. This work provides an effective strategy for designing advanced ferroelectric photocatalytic systems. Ferroelectrics, which exhibit excellent charge separation ability, suffer from poor photocatalytic activity. The authors unveil the limitations in charge extraction and offer strategies to design high-performance photocatalysts by eliminating surface defects.

The investigation and prediction of new trends and technologies for mobile cellular networks is of utmost importance for researchers and network providers to quickly identify promising developments. With the verge of the fifth generation of mobile communications (5G), networks become more and more heterogeneous and dynamic while the amount of active users within a cell keeps ever increasing. Therefore, the search for more efficient network layouts and configurations attracts massive attention while on the other hand becomes more and more complex. In this contribution, we present the Vienna 5G system level simulator, which allows to perform numerical performance evaluation of large-scale multi-tier networks, with numerous types of network nodes. The simulator is based on Matlab and is implemented in a modular fashion, to conveniently investigate arbitrary network and parameter constellations, which can be enhanced effortlessly. We first discuss the distinguishing aspects of our simulator platform, describe its structure, and then showcase its functionality by demonstrating the key aspects in more detail.

Photocatalytic overall water splitting remains limited by inefficient charge separation and utilization in reactions. Al-doped SrTiO 3 exhibiting near-100% apparent quantum efficiency for overall water splitting indicates nearly complete charge separation and surface catalytic efficiency. Although Al doping has been assumed to enhance charge separation and transfer, the exact role of Al is still unclear. Here, using spatiotemporal surface photovoltage imaging, we show that a gradient Al doping in Al-doped SrTiO 3 generates a built-in electric field that drives photogenerated holes from the bulk toward surface trap sites in the form of hydroxylated Al-O-Ti, prolonging their lifetime from ~100 ns to 10 ms. Spectroscopic analyses reveal that these hydroxylated Al sites serve as key centers for water adsorption, facilitating water oxidation. These findings underscore the pivotal role of Al in the spatiotemporal alignment of hole transfer and surface catalytic water oxidation, enabling high-efficiency photocatalysis in overall water splitting. The pivotal role of Al in the spatiotemporal alignment of hole transfer and surface catalytic water oxidation in SrTiO 3 :Al enables highly efficient photocatalytic overall water splitting.

We construct a microscopic model to study discrete randomness in bistable systems coupled to an environment comprising many degrees of freedom. A quartic double well is bilinearly coupled to a finite number N of harmonic oscillators. Solving the time-reversal invariant Hamiltonian equations of motion numerically, we show that for N=1, the system exhibits a transition with increasing coupling strength from integrable to chaotic motion, following the Kolmogorov-Arnol’d-Moser (KAM) scenario. Raising N to values of the order of 10 and higher, the dynamics crosses over to a quasi-relaxation, approaching either one of the stable equilibria at the two minima of the potential. We corroborate the irreversibility of this relaxation on other characteristic timescales of the system by recording the time dependences of autocorrelation, partial entropy, and the frequency of jumps between the wells as functions of N and other parameters. Preparing the central system in the unstable equilibrium at the top of the barrier and the bath in a random initial state drawn from a Gaussian distribution, symmetric under spatial reflection, we demonstrate that the decision whether to relax into the left or the right well is determined reproducibly by residual asymmetries in the initial positions and momenta of the bath oscillators. This result reconciles the randomness and spontaneous symmetry breaking of the asymptotic state with the conservation of entropy under canonical transformations and the manifest symmetry of potential and initial condition of the bistable system.

Two-dimensional (2D) aluminum nitride (AlN) represents a promising material with unique properties predicted by density functional theory (DFT), characterized by a honeycomb lattice where Al and N atoms exhibit threefold in-plane coordination. However, the synthesis of free-standing AlN nanosheets has been challenging due to the crystal configurations of the well-known bulk AlN, which presents a hexagonal wurtzite structure with a tetrahedral coordination, preventing its exfoliation to obtain nanosheets. Herein, we propose a facile method involving the preparation of layered-structured aluminum carbonitrides, Al 5 C 3 N, followed by exfoliation into AlN nanosheets, offering a potential route for producing 2D AlN. The Al 5 C 3 N precursor was chemically etched in hydrofluoric acid (HF), breaking the Al-C bonds and exposing the AlN nanosheets. The development of this synthesis method opens up opportunities towards the preparation of 2D AlN and the investigation of its unique properties for applications in sensors and microelectronics. Two-dimensional aluminum nitride holds promise for advanced applications, yet its synthesis is hindered by the bulk material’s hexagonal wurtzite structure which prevents facile exfoliation. Here, the authors present a method using layered-structured aluminum carbonitrides as precursors and hydrofluoric acid chemical etching to produce AlN nanosheets, paving the way for innovations in sensors and microelectronics.

Die demografische Entwicklung in Deutschland hat einen erheblichen Einfluss auf die Altersstruktur in Unternehmen. In vielen Regionen und Branchen sinkt das Angebot an jungen Arbeitskräften. Gleichzeitig führen die Abschaffung der staatlichen Unterstützung der Frühverrentung und die Anhebung der Regelaltersrente auf 67 Jahre dazu, dass immer mehr ältere Menschen arbeiten. Das Durchschnittsalter in den Unternehmen steigt; die Notwendigkeit der (Weiter-)Beschäftigung erfahrener Mitarbeiter ebenfalls. Schon seit mehreren Jahrzehnten beschäftigt sich die Forschung mit dem Erhalt der körperlichen und geistigen Leistungsfähigkeit älterer Beschäftigter. Seit Anfang der 2000er Jahre rückte auch die Arbeitsmotivation als eine zu berücksichtigende Komponente verstärkt ins Blickfeld. Mitarbeiter nur für eine möglichste lange Beschäftigung zu befähigen, wurde nicht mehr als ausreichend betrachtet. Es galt gleichzeitig, ihren Leistungswillen zu erhalten. Diese Studie untersucht mehrere Komponenten der Arbeitsmotivation und deren Zusammenhang zum Alter. Neben der Frage, ob sich jüngere und ältere Mitarbeiter hinsichtlich ihrer intrinsischen Arbeitsmotivation grundsätzlich unterscheiden, stehen zwei Aspekte im Fokus. Zum einen wurde untersucht, ob ältere Mitarbeiter spezifische Arbeits- und Organisationsfaktoren für ihre Motivation benötigen. Dafür wurde überprüft, ob sich jüngere und ältere Mitarbeiter in ihren arbeitsbezogenen Motiven unterscheiden. Zum anderen sollte herausgefunden werden, ob es altersabhängige Unterschiede im Vorhandensein bzw. der Wahrnehmung bestimmter Arbeitsbedingungen gibt. Die untersuchten Motive werden größtenteils auf die Selbstbestimmungstheorie von Deci und Ryan zurückgeführt. Die Arbeitsbedingungen auf das Modell der Jobcharakteristika von Hackman und Oldham. Daneben spielen einige neuere Forschungen zur Generativität und der Möglichkeit zur Weitergabe von Wissen eine Rolle. Die Untersuchung macht altersbedingte Unterschiede sowohl in der Wahrnehmung bestimmter Motive als auch einiger Arbeitsbedingungen sichtbar. Sie zeigt auch, dass die intrinsische Motivation, die Arbeitszufriedenheit und das Commitment gegenüber dem Unternehmen bei jüngeren mindestens genauso hoch ausgeprägt sind wie bei älteren Mitarbeitern. Zudem wird deutlich, dass es weitere soziodemografische Variablen gibt, die eine Rolle für die untersuchten Komponenten der Arbeitsmotivation spielen. Der vermutete Zusammenhang mit dem Alter wird von zahlreichen Faktoren beeinflusst.

The ablation material used during the National Ignition Campaign, a glow- discharge polymer (GDP), does not couple as efficiently as simulations indicated to the multiple- shock inducing radiation drive environment created by laser power profile [1]. We investigate the performance of two other ablators, boron carbide (B4C) and high-density carbon (HDC) and compare with GDP under the same hohlraum conditions. Ablation performance is determined through measurement of the shock speed produced in planar samples of the ablator subjected to the identical multiple-shock inducing radiation drive environments that are similar to a generic three-shock ignition drive. Simulations are in better agreement with the off-Hugoniot performance of B4C than either HDC or GDP.