Quantum information scrambling and chemical reactions.

The ultimate regularity of quantum mechanics creates a tension with the assumption of classical chaos used in many of our pictures of chemical reaction dynamics. Out-of-time-order correlators (OTOCs) provide a quantum analog to the Lyapunov exponents that characterize classical chaotic motion. Maldacena, Shenker, and Stanford have suggested a fundamental quantum bound for the rate of information scrambling, which resembles a limit suggested by Herzfeld for chemical reaction rates. Here, we use OTOCs to study model reactions based on a double-well reaction coordinate coupled to anharmonic oscillators or to a continuum oscillator bath. Upon cooling, as one enters the tunneling regime where the reaction rate does not strongly depend on temperature, the quantum Lyapunov exponent can approach the scrambling bound and the effective reaction rate obtained from a population correlation function can approach the Herzfeld limit on reaction rates: Tunneling increases scrambling by expanding the state space available to the system. The coupling of a dissipative continuum bath to the reaction coordinate reduces the scrambling rate obtained from the early-time OTOC, thus making the scrambling bound harder to reach, in the same way that friction is known to lower the temperature at which thermally activated barrier crossing goes over to the low-temperature activationless tunneling regime. Thus, chemical reactions entering the tunneling regime can be information scramblers as powerful as the black holes to which the quantum Lyapunov exponent bound has usually been applied.

Efficient Holes Abstraction by Precisely Decorating Ruthenium Single Atoms and RuOx Clusters on ZnIn2S4 for Photocatalytic Pure Water Splitting.

Developing efficient photocatalysts for two-electron water splitting with simultaneous H2O2 and H2 generation shows great promise for practical application. Currently, the efficiency of two-electron water splitting is still restricted by the low utilization of photogenerated charges, especially holes, of which the transfer rate is much slower than that of electrons. Herein, Ru single atoms and RuOx clusters are co-decorated on ZnIn2S4 (RuOx/Ru-ZIS) to employ as multifunctional sites for efficient photocatalytic pure water splitting. Doping of Ru single atoms in the ZIS basal plane enhances holes abstraction from bulk ZIS by regulating the electronic structure, and RuOx clusters offer a strong interfacial electric field to remarkably promote the out-of-plane migration of holes from ZIS. Moreover, Ru single atoms and RuOx clusters also serve as active sites for boosting surface water oxidation. As a result, an excellent H2 and H2O2 evolution rates of 581.9 µmol g-1 h-1 and 464.4 µmol g-1 h-1 is achieved over RuOx/Ru-ZIS under visible light irradiation, respectively, with an apparent quantum efficiency (AQE) of 4.36% at 400 nm. This work paves a new way to increase charge utilization by manipulating photocatalyst using single atom and clusters.

Harnessing Holey MXene/Graphene Oxide Heterostructure to Maximize Ion Channels in Lamellar Film for High-Performance Capacitive Deionization.

2D Ti3C2Tx MXene-based film electrodes with metallic conductivity and high pseudo-capacitance are of considerable interest in cutting-edge research of capacitive deionization (CDI). Further advancement in practical use is however impeded by their intrinsic limitations, e.g., tortuous ion diffusion pathway of layered stacking, vulnerable chemical stability, and swelling-prone nature of hydrophilic MXene nanosheet in aqueous environment. Herein, a nanoporous 2D/2D heterostructure strategy is established to leverage both merits of holey MXene (HMX) and holey graphene oxide (HGO) nanosheets, which optimize ion transport shortcuts, alleviate common restacking issues, and improve film's mechanical and chemical stability. In this design, the nanosized in-plane holes in both handpicked building blocks build up ion diffusion shortcuts in the composite laminates to accelerate the transport and storage of ions. As a direct outcome, the HMX/rHGO films exhibit remarkable desalination capacity of 57.91 mg g-1 and long-term stability in 500 mg L-1 NaCl solution at 1.2 V. Moreover, molecular dynamics simulations and ex situ wide angle X-ray scattering jointly demonstrate that the conductive 2D/2D networks and ultra-short ion diffusion channels play critical roles in the ion intercalation/deintercalation process of HMX/rHGO films. The study paves an alternative design concept of freestanding CDI electrodes with superior ion transport efficiency.

Ultrastrong and Reusable Solar‒Thermal‒Electric Generators by Economical Starch Vitrimers.

In frigid regions, it is imperative to possess functionality materials that are ultrastrong, reusable, and economical, providing self-generated heat and electricity. One promising solution is a solar‒thermal‒electric (STE) generator, composed of solar‒thermal conversion phase change composites (PCCs) and temperature-difference power-generation-sheets. However, the existing PCCs face challenges with conflicting requirements for solar‒thermal conversion efficiency and mechanical robustness, mainly due to monotonous functionalized aerogel framework. Herein, a novel starch vitrimer aerogel is proposed that incorporates orientational distributed carboxylated carbon nanotubes (CCNT) to create PCC. This innovative design integrates large through-holes, mechanical robustness, and superior solar‒thermal conversion. Remarkably, PCC with only 0.8 wt.% CCNT loading achieves 85.8 MPa compressive strength, 102.4 °C at 200 mW cm-2 irradiation with an impressive 92.9% solar-thermal conversion efficiency. Noteworthy, the STE generator assembled with PCC harvests 99.1 W m-2 output power density, surpassing other reported STE generators. Strikingly, even under harsh conditions of -10 °C and 10 mW cm‒2 irradiation, the STE generator maintains 20 °C for PCC with 325 mV output voltage and 45 mA current, showcasing enhanced electricity generation in colder environments. This study introduces a groundbreaking STE generator, paving the way for self-sufficient heat and electricity supply in cold regions.

Hyperboloidal approach for static spherically symmetric spacetimes: a didactical introduction and applications in black-hole physics.

This work offers a didactical introduction to the calculations and geometrical properties of a static, spherically symmetric spacetime foliated by hyperboloidal time surfaces. We discuss the various degrees of freedom involved, namely the height function, responsible for introducing the hyperboloidal time coordinate, and a radial compactification function. A central outcome is the expression of the Trautman-Bondi mass in terms of the hyperboloidal metric functions. Moreover, we apply this formalism to a class of wave equations commonly used in black-hole perturbation theory. Additionally, we provide a comprehensive derivation of the hyperboloidal minimal gauge, introducing two alternative approaches within this conceptual framework: the in-out and out-in strategies. Specifically, we demonstrate that the height function in the in-out strategy follows from the well-known tortoise coordinate by changing the sign of the terms that become singular at future null infinity. Similarly, for the out-in strategy, a sign change also occurs in the tortoise coordinate's regular terms. We apply the methodology to the following spacetimes: Singularity-approaching slices in Schwarzschild, higher-dimensional black holes, black hole with matter halo, and Reissner-Nordström-de Sitter. From this heuristic study, we conjecture that the out-in strategy is best adapted for black hole geometries that account for environmental or effective quantum effects. This article is part of a discussion meeting issue 'At the interface of asymptotics, conformal methods and analysis in general relativity'.

Analytic and conformal scattering in general relativity.

This paper is about two important trends of scattering theory in general relativity: time-dependent spectral analytic scattering and conformal scattering. The former was initiated by Jonathan Dimock and Bernard Kay in the mid-1980s and is based on spectral and functional analysis. The latter was proposed by Roger Penrose in 1965 and then constructed for the first time by Gerard Friedlander in 1980 by putting together Penrose's conformal method and another analytic approach to scattering: the Lax-Phillips theory due to Peter Lax and Ralph Phillips. We shall review the history of the two approaches and explain their general principles. We shall also explore an important question: 'can the tools of one approach be used to obtain a complete construction in the other?' This article is part of a discussion meeting issue 'At the interface of asymptotics, conformal methods and analysis in general relativity'.

The impact of image contrast, resolution and reader expertise on black hole identification in Multiple Sclerosis.

OBJECTIVES: In the neuroradiological work-up of Multiple Sclerosis (MS), the detection of "black holes" (BH) represent an information of undeniable importance. Nevertheless, different sequences can be used in clinical practice to evaluate BH in MS. Aim of this study was to investigate the possible impact of different sequences, resolutions, and levels of expertise on the intra- and inter-rater reliability identification of BH in MS. METHODS: Brain MRI scans of 85 MS patients (M/F = 22/63; mean age = 36.0 ± 10.2 years) were evaluated in this prospective single-center study. The acquisition protocol included a 3 mm SE-T1w sequence, a 1 mm 3D-GrE-T1w sequence from which a resliced 3 mm sequence was also obtained. Images were evaluated independently by two readers of different expertise at baseline and after a wash-out period of 30 days. The intraclass correlation coefficient (ICC) was calculated as an index of intra and inter-reader reliability. RESULTS: For both readers, the intra-reader ICC analysis showed that the 3 mm SE-T1w and 3 mm resliced GrE-T1w images achieved an excellent performance (both with an ICC ≥ 0.95), while 1 mm 3D-GrE-T1w scans achieved a moderate one (ICC < 0.90). The inter-reader analysis showed that each of the three sequences achieved a moderate performance (all ICCs < 0.90). CONCLUSIONS: The 1 mm 3D-GrE-T1w sequence seems to be prone to a greater intra-reader variability compared to the 3 mm SE-T1w, with this effect being driven by the higher spatial resolution of the first sequence. To ensure reliability levels comparable with the standard SE-T1w in BH count, an assessment on a 3 mm resliced GrE-T1w sequence should be recommended.

Microbial oases in the ice: A state-of-the-art review on cryoconite holes as diversity hotspots and their scientific connotations.

Cryoconite holes, small meltwater pools on the surface of glaciers and ice sheets, represent extremely cold ecosystems teeming with diverse microbial life. Cryoconite holes exhibit greater susceptibility to the impacts of climate change, underlining the imperative nature of investigating microbial communities as an essential module of polar and alpine ecosystem monitoring efforts. Microbes in cryoconite holes play a critical role in nutrient cycling and can produce bioactive compounds, holding promise for industrial and pharmaceutical innovation. Understanding microbial diversity in these delicate ecosystems is essential for effective conservation strategies. Therefore, this review discusses the microbial diversity in these extreme environments, aiming to unveil the complexity of their microbial communities. The current study envisages that cryoconite holes as distinctive ecosystems encompass a multitude of taxonomically diverse and functionally adaptable microorganisms that exhibit a rich microbial diversity and possess intricate ecological functions. By investigating microbial diversity and ecological functions of cryoconite holes, this study aims to contribute valuable insights into the broader field of environmental microbiology and enhance further understanding of these ecosystems. This review seeks to provide a holistic overview regarding the formation, evolution, characterization, and molecular adaptations of cryoconite holes. Furthermore, future research directions and challenges underlining the need for long-term monitoring, and ethical considerations in preserving these pristine environments are also provided. Addressing these challenges and resolutely pursuing future research directions promises to enrich our comprehension of microbial diversity within cryoconite holes, revealing the broader ecological and biogeochemical implications. The inferences derived from the present study will provide researchers, ecologists, and policymakers with a profound understanding of the significance and utility of cryoconite holes in unveiling the microbial diversity and its potential applications.

Biological ultrathin amniotic membrane flap to close refractory macular holes associated with high myopia.

PURPOSE: To propose an ultrathin biological amniotic membrane (btAM) thinner than 10 µm as the graft to treat highly myopic macular holes (MH). METHODS: This pilot study included 14 patients affected by refractory macular holes associated with high myopia. btAM was used as a bandage covering the holes. The best-corrected visual acuity (BCVA), fundus photography, and optical coherence tomography (OCT) before and after surgery were compared. RESULTS: The mean MH size was 865.93 ± 371.72 µm and all the MHs achieved anatomical closure. The btAM located centrally and fully on MHs from fundus photography yet no obvious visual masking was complained. The average BCVA 1 month, 3, and 6 months after surgery were 0.95 ± 0.24, 0.92 ± 0.23, 0.92 ± 0.23 logMAR, respectively, improved significantly compared to pre-operative BCVA (1.24 ± 0.42 logMAR, all P < 0.05). Ten out of 14 (71.4%) exhibited 2C closure patterns (formally closed and no bare RPE) on OCT. CONCLUSION: The btAM thinner showed a favorable anatomical success with less risk of parafoveal atrophy or iatrogenic injuries and shortened the dissolving time.

Voltammetric co-determination of lead and copper in gunshot residue based on iron oxide particle/spent coffee grounds-modified electrode.

A novel electrochemical sensor was developed for the detection of lead (Pb) and copper (Cu) ions using spent coffee grounds decorated with iron oxide particles (FeO/SCG). The FeO-decorated SCG was used to modify a glassy carbon electrode (GCE). FeO, SCG, and FeO/SCG were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The electrochemical properties of the modified electrode were characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The electrode modifications increased the active surface area and electron transfer and enhanced the accumulation of the target analyte. In the optimal condition, the developed sensor showed linear ranges of 1.0 µg L-1-0.05 mg L-1 and 0.05 mg L-1-0.8 mg L-1 for Pb2+ and 5.0 µg L-1-0.1 mg L-1 and 0.1 mg L-1-0.8 mg L-1 for Cu2+. The limit of detection (LOD) was 1.0 µg L-1 for Pb2+ and 2.4 µg L-1 for Cu2+. The developed sensor was successfully applied to determine Pb2+ and Cu2+ in bullet holes. The results were in good agreement with those obtained by inductively coupled plasma optical emission spectrometry (ICP/OES).

3D Reverse-Time Migration Imaging for Multiple Cross-Hole Research and Multiple Sensor Settings of Cross-Hole Seismic Exploration.

The two-dimensional (2D) cross-hole seismic computed tomography (CT) imaging acquisition method has the potential to characterize the target zone optimally compared to surface seismic surveys. It has wide applications in oil and gas exploration, engineering geology, etc. Limited to 2D hole velocity profiling, this method cannot acquire three-dimensional (3D) information on lateral geological structures outside the profile. Additionally, the sensor data received by cross-hole seismic exploration constitute responses from geological bodies in 3D space and are potentially affected by objects outside the well profiles, distorting the imaging results and geological interpretation. This paper proposes a 3D cross-hole acoustic wave reverse-time migration imaging method to capture 3D cross-hole geological structures using sensor settings in multi-cross-hole seismic research. Based on the analysis of resulting 3D cross-hole images under varying sensor settings, optimizing the observation system can aid in the cost-efficient obtainment of the 3D underground structure distribution. To verify this method's effectiveness on 3D cross-hole structure imaging, numerical simulations were conducted on four typical geological models regarding layers, local high-velocity zones, large dip angles, and faults. The results verify the model's superiority in providing more reliable and accurate 3D geological information for cross-hole seismic exploration, presenting a theoretical basis for processing and interpreting cross-hole data.

Node Role Selection and Rotation Scheme for Energy Efficiency in Multi-Level IoT-Based Heterogeneous Wireless Sensor Networks (HWSNs).

The emergence of Internet of Things (IoT)-based heterogeneous wireless sensor network (HWSN) technology has become widespread, playing a significant role in the development of diverse human-centric applications. The role of efficient resource utilisation, particularly energy, becomes further critical in IoT-based HWSNs than it was in WSNs. Researchers have proposed numerous approaches to either increase the provisioned resources on network devices or to achieve efficient utilisation of these resources during network operations. The application of a vast proportion of such methods is either limited to homogeneous networks or to a single parameter and limited-level heterogeneity. In this work, we propose a multi-parameter and multi-level heterogeneity model along with a cluster-head rotation method that balances energy and maximizes lifetime. This method achieves up to a 57% increase in throughput to the base station, owing to improved intra-cluster communication in the IoT-based HWSN. Furthermore, for inter-cluster communication, a mathematical framework is proposed that first assesses whether the single-hop or multi-hop inter-cluster communication is more energy efficient, and then computes the region where the next energy-efficient hop should occur. Finally, a relay-role rotation method is proposed among the potential next-hop nodes. Results confirm that the proposed methods achieve 57.44%, 51.75%, and 17.63% increase in throughput of the IoT-based HWSN as compared to RLEACH, CRPFCM, and EERPMS, respectively.

d-Band Hole Dynamics in Gold Nanoparticles Measured with Time-Resolved Emission Upconversion Microscopy.

The performance of photocatalysts and photovoltaic devices can be enhanced by energetic charge carriers produced from plasmon decay, and the lifetime of these energetic carriers greatly affects overall efficiencies. Although hot electron lifetimes in plasmonic gold nanoparticles have been investigated, hot hole lifetimes have not been as thoroughly studied in plasmonic systems. Here, we demonstrate time-resolved emission upconversion microscopy and use it to resolve the lifetime and energy-dependent cooling of d-band holes formed in gold nanoparticles by plasmon excitation and by following plasmon decay into interband and then intraband electron-hole pairs.

Nonclassical Mechanism of Metal-Enhanced Photoluminescence of Quantum Dots.

Metal-enhanced photoluminescence is able to provide a robust signal even from a single emitter and is promising in applications in biosensors and optoelectronic devices. However, its realization with semiconductor nanocrystals (e.g., quantum dots, QDs) is not always straightforward due to the hidden and not fully described interactions between plasmonic nanoparticles and an emitter. Here, we demonstrate nonclassical enhancement (i.e., not a conventional electromagnetic mechanism) of the QD photoluminescence at nonplasmonic conditions and correlate it with the charge exchange processes in the system, particularly with high efficiency of the hot-hole generation in gold nanoparticles and the possibility of their transfer to QDs. The hole injection returns a QD from a charged nonemitting state caused by hole trapping by surface and/or interfacial traps into an uncharged emitting state, which leads to an increased photoluminescence intensity. These results open new insights into metal-enhanced photoluminescence, showing the importance of the QD surface states in this process.

Halogen Bond via an Electrophilic π-Hole on Halogen in Molecules: Does It Exist?

This study reveals a new non-covalent interaction called a π-hole halogen bond, which is directional and potentially non-linear compared to its sister analog (σ-hole halogen bond). A π-hole is shown here to be observed on the surface of halogen in halogenated molecules, which can be tempered to display the aptness to form a π-hole halogen bond with a series of electron density-rich sites (Lewis bases) hosted individually by 32 other partner molecules. The [MP2/aug-cc-pVTZ] level characteristics of the π-hole halogen bonds in 33 binary complexes obtained from the charge density approaches (quantum theory of intramolecular atoms, molecular electrostatic surface potential, independent gradient model (IGM-δginter)), intermolecular geometries and energies, and second-order hyperconjugative charge transfer analyses are discussed, which are similar to other non-covalent interactions. That a π-hole can be observed on halogen in halogenated molecules is substantiated by experimentally reported crystals documented in the Cambridge Crystal Structure Database. The importance of the π-hole halogen bond in the design and growth of chemical systems in synthetic chemistry, crystallography, and crystal engineering is yet to be fully explicated.

Rational Photodeposition of Cobalt Phosphate on Flower-like ZnIn2S4 for Efficient Photocatalytic Hydrogen Evolution.

The high electrons and holes recombination rate of ZnIn2S4 significantly limits its photocatalytic performance. Herein, a simple in situ photodeposition strategy is adopted to introduce the cocatalyst cobalt phosphate (Co-Pi) on ZnIn2S4, aiming at facilitating the separation of electron-hole by promoting the transfer of photogenerated holes of ZnIn2S4. The study reveals that the composite catalyst has superior photocatalytic performance than blank ZnIn2S4. In particular, ZnIn2S4 loaded with 5% Co-Pi (ZnIn2S4/5%Co-Pi) has the best photocatalytic activity, and the H2 production rate reaches 3593 µmol·g-1·h-1, approximately double that of ZnIn2S4 alone. Subsequent characterization data demonstrate that the introduction of the cocatalyst Co-Pi facilitates the transfer of ZnIn2S4 holes, thus improving the efficiency of photogenerated carrier separation. This investigation focuses on the rational utilization of high-content and rich cocatalysts on earth to design low-cost and efficient composite catalysts to achieve sustainable photocatalytic hydrogen evolution.

Magnetic Black Hole Thermodynamics in an Extended Phase Space with Nonlinear Electrodynamics.

We study Einstein's gravity coupled to nonlinear electrodynamics with two parameters in anti-de Sitter spacetime. Magnetically charged black holes in an extended phase space are investigated. We obtain the mass and metric functions and the asymptotic and corrections to the Reissner-Nordström metric function when the cosmological constant vanishes. The first law of black hole thermodynamics in an extended phase space is formulated and the magnetic potential and the thermodynamic conjugate to the coupling are obtained. We prove the generalized Smarr relation. The heat capacity and the Gibbs free energy are computed and the phase transitions are studied. It is shown that the electric fields of charged objects at the origin and the electrostatic self-energy are finite within the nonlinear electrodynamics proposed.

Exception to the Puppe's rule reloaded and a warning in the interpretation of skull fractures: they run even through recent craniotomy burr holes.

A possible "exception" to Puppe's rule regarding the intersection of skull fractures has been previously addressed due to the observation that skull fractures can pass through old and remodeled craniotomies. In a further case presented herein, however, it was shown that cranial fractures are also able to pass through recent burr holes, a phenomenon never previously described. A 63-year-old man sustained a self-inflicted gunshot wound to the right temple region, with an exit wound in the left temporal region. Twenty-five days prior, the patient had undergone parietal craniotomy for the evacuation of a subdural hematoma secondary to glioblastoma. Among the fracture lines originating from the exit wound, one traversed the craniotomy hole, terminating approximately 1.4 cm beyond its contralateral margin. This illustrates that cranial fractures possess the capability to cross "fresh" burr holes that have not undergone to bone remodeling. Consequently, the evaluation of Puppe's rule should be reconsidered, particularly in cases of gunshot injuries, wherein fractures pass through full-thickness circular lesions (such as entry and exit wounds). The varied scenarios underscore the potential for fractures to "pass through" these burr holes if they have not themselves generated fracture lines, as may be the case with entry holes with circular lesions without fractures.

Synergy of Photogenerated Electrons and Holes toward Efficient Photocatalytic Urea Synthesis from CO2 and N2.

Directly coupling N2 and CO2 to synthesize urea by photocatalysis paves a sustainable route for urea synthesis, but its performance is limited by the competition of photogenerated electrons between N2 and CO2, as well as the underutilized photogenerated holes. Herein, we report an efficient urea synthesis process involving photogenerated electrons and holes in respectively converting CO2 and N2 over a redox heterojunction consisting of WO3 and Ni single-atom-decorated CdS (Ni1-CdS/WO3). For the photocatalytic urea synthesis from N2 and CO2 in pure water, Ni1-CdS/WO3 attained a urea yield rate of 78 µM h-1 and an apparent quantum yield of 0.15 % at 385 nm, which ranked among the best photocatalytic urea synthesis performance reported. Mechanistic studies reveal that the N2 was converted into NO species by ⋅OH radicals generated from photogenerated holes over the WO3 component, meanwhile, the CO2 was transformed into *CO species over the Ni site by photogenerated electrons. The generated NO and *CO species were further coupled to form *OCNO intermediate, then gradually transformed into urea. This work emphasizes the importance of reasonably utilizing photogenerated holes in photocatalytic reduction reactions.

The Galactic Center as a laboratory for theories of gravity and dark matter.

The Galactic Center (GC) of the Milky Way, thanks to its proximity, allows to perform astronomical observations that investigate physical phenomena at the edge of astrophysics and fundamental physics. As such, it offers a unique laboratory to probe gravity, where one can not only test the basic predictions of general relativity (GR), but is also able to falsify theories that, over time, have been proposed to modify or extend GR; to test different paradigms of dark matter; and to place constraints on putative models that have been formulated as alternatives to the standard black hole paradigm in GR. In this review we provide a general overview of the history of observations of the GC, emphasizing the importance, in particular on the smallest-observable scales, that they had in opening a new avenue to improve our understanding of the underlying theory of gravity in the surrounding of a supermassive compact object.