BINA

The spacetime curvature in the vicinity of massive black holes induces the bending of ray trajectories and the trapping of light in a specific region of space called the photon sphere. We mimic in the laboratory the behavior of waves near a black hole by investigating the modes of vibration on a 3D curved surface corresponding to a particular metric of the black hole. This surface can be transformed to a flat disk with non-uniform distribution of refractive index. Here, we consider elastic waves guided in a thin plate with non-uniform thickness, which corresponds to a varying velocity. Selective laser melting has been used to 3D-print our model with an aluminum alloy. A short pulse is propagated, and the spatiotemporal profile of the velocity-field is recorded by scanning a laser vibrometer. The quasimodes of the system are obtained by modal analysis in the Fourier domain. We find two different classes of modes:(1) Modes …

Visualizing the current distribution in materials is a powerful tool to investigate and understand unconventional transport they exhibit. In the present work, we study a few microns thick devices of the layered chalcogenide material 1T-TaS 2. Pulsed DC excitation of the commensurate charge density wave (CCDW) phase in the system leads to a controllable, non-volatile, resistance-switching states. We use scanning SQUID microscopy to image, in-situ, the local current density map by mapping the field generated by the current flow. The images reveal the presence of electrical domains in the device and their effect on the current flow.

This manuscript introduces and shares MATLAB code for simulating the behavior of a temporal SU(1,1) interferometer, offering a valuable resource for researchers and practitioners in the field. The provided code facilitates comprehensive simulations of the interferometer’s dynamics, enabling the exploration of its response to various parameters and scenarios. The simulations delve into the interferometer’s performance, emphasizing its sensitivity to ultrafast phase changes and its concurrent operation in both the time and spectral domains. By making the MATLAB code openly available, this contribution aims to foster collaboration, enhance reproducibility, and serve as a foundational tool for researchers delving into the design and analysis of temporal SU(1,1) interferometers. The manuscript provides detailed documentation on code usage, empowering users to adapt and extend the simulations for their specific …

G54. 00011: Light chaotic dynamics and ray engineering transformed from curved to flat space

Self‐healing (SH) of (opto)electronic material damage can have a huge impact on resource sustainability. The rising interest in halide perovskite (HaP) compounds over the past decade is due to their excellent semiconducting properties for crystals and films, even if made by low‐temperature solution‐based processing. Direct proof of self‐healing in Pb‐based HaPs is demonstrated through photoluminescence recovery from photodamage, fracture healing and their use as high‐energy radiation and particle detectors. Here, the question of how to find additional semiconducting materials exhibiting SH, in particular lead‐free ones is addressed. Applying a data‐mining approach to identify semiconductors with favorable mechanical and thermal properties, for which Pb HaPs are clear outliers, it is found that the Cs2AuIAuIIIX6, (X = I, Br, Cl) family, which is synthesized and tested for SH. This is the first demonstration of …

Background Bacterial biocontrol agents that antagonize soilborne pathogens are increasingly considered as alternatives to chemical pesticides, but their in-vivo efficacy is often inconsistent, restricting commercial use. The efficacy of a biocontrol agent can depend on rhizosphere competence and its interaction with native microbiomes, which can effect ecosystem functioning. This study investigated the capacity of a Bacillus cereus sensu lato (Bcsl) biocontrol strain (S-25) to persist on roots and in the rhizosphere of cucumber, and evaluated its impact on bacterial and fungal community composition in the rhizosphere, in the absence and presence of Rhizoctonia solani, the causative agent of damping-off disease in young seedlings. Results Following amendment, S-25 abundance in the cucumber rhizosphere decreased by two orders of magnitude, but remained relatively high for the duration of the experiment, in … Background Results

Vertical growth of Zn crystals is widely recognized as a primary factor responsible for the premature failure of aqueous Zn batteries. These vertically aligned sharp-tipped Zn plates can easily pierce the separator, propagating toward the cathode side, and short-circuit the cell. While inhibition of this phenomenon may be achieved by electrolyte engineering or manipulation of the anode’s interface, we propose herein an effective suppression of vertical Zn growth by replacing the conventional separators with highly affordable commercially available printing paper. Based on electrochemical and structural studies followed by small punch measurements, we found that these papers comprise nanometric rigid ceramic particles that act as a physical barrier for the growth of Zn plates, preventing their penetration through the paper-based separator. As a result, the examined cells demonstrate excellent long-term performance …

The high concentration of antibiotics in aquatic environments is a serious environmental issue. In response, researchers have explored photocatalytic degradation as a potential solution. Through chemical vapor deposition (CVD), we synthesized copper selenide (β-Cu2−xSe) and found it an effective catalyst for degrading tetracycline hydrochloride (TC-HCl). The catalyst demonstrated an impressive degradation efficiency of approximately 98% and a reaction rate constant of 3.14 × 10−2 min−1. Its layered structure, which exposes reactive sites, contributes to excellent stability, interfacial charge transfer efficiency, and visible light absorption capacity. Our investigations confirmed that the principal active species produced by the catalyst comprises O2− radicals, which we verified through trapping experiments and electron paramagnetic resonance (EPR). We also verified the TC-HCl degradation mechanism using high-performance liquid chromatography–mass spectrometry (LC-MS). Our results provide valuable insights into developing the β-Cu2−xSe catalyst using CVD and its potential applications in environmental remediation.

The electrocatalytic oxygen evolution reaction (OER) is an arduous step in water splitting due to its slow reaction rate and large overpotential. Herein, we synthesized glycerate-anion-intercalated nickel–iron glycerates (NiFeGs) using a one-step solvothermal reaction. We designed various NiFeGs by tuning the molar ratio between Ni and Fe to obtain Ni4Fe1G, Ni3Fe1G, Ni3Fe2G, and Ni1Fe1G, which we tested for their OER performance. We initially analyzed the catalytic performance of powder samples immobilized on glassy carbon electrodes using a binder. Ni3Fe2G outperformed the other NiFeG compositions, including NiFe layered double hydroxide (LDH). It exhibited an overpotential of 320 mV at a current density of 10 mA cm–2 in an electrolytic solution of pH 14. We then synthesized carbon paper (CP)-modified Ni3Fe2G as a self-supported electrode (Ni3Fe2G/CP), and it exhibited a high current density (100 mA cm−2) at a low overpotential of 300 mV. The redox peak analysis for the NiFeGs revealed that the initial step of the OER is the formation of γ-NiOOH, which was further confirmed by a post-Raman analysis. We extensively analyzed the catalyst’s stability and lifetime, the nature of the active sites, and the role of the Fe content to enhance the OER performance. This work may provide the motivation to study metal-alkoxide-based efficient OER electrocatalysts that can be used for alkaline water electrolyzer applications.

IntroductionAnalysis of an individual’s immunoglobulin (IG) gene repertoire requires the use of high-quality germline gene reference sets. When sets only contain alleles supported by strong evidence, AIRR sequencing (AIRR-seq) data analysis is more accurate and studies of the evolution of IG genes, their allelic variants and the expressed immune repertoire is therefore facilitated.MethodsThe Adaptive Immune Receptor Repertoire Community (AIRR-C) IG Reference Sets have been developed by including only human IG heavy and light chain alleles that have been confirmed by evidence from multiple high-quality sources. To further improve AIRR-seq analysis, some alleles have been extended to deal with short 3’ or 5’ truncations that can lead them to be overlooked by alignment utilities. To avoid other challenges for analysis programs, exact paralogs (e.g. IGHV1-69*01 and IGHV1-69D*01) are only represented once in each set, though alternative sequence names are noted in accompanying metadata.Results and discussionThe Reference Sets include less than half the previously recognised IG alleles (e.g. just 198 IGHV sequences), and also include a number of novel alleles: 8 IGHV alleles, 2 IGKV alleles and 5 IGLV alleles. Despite their smaller sizes, erroneous calls were eliminated, and excellent coverage was achieved when a set of repertoires comprising over 4 million V(D)J rearrangements from 99 individuals were analyzed using the Sets. The version-tracked AIRR-C IG Reference Sets are freely available at the OGRDB website (https://ogrdb.airr-community.org/germline_sets/Human) and will be regularly updated to include newly …

Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year‐on‐year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non‐vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its ‘Minimal Information for Studies of Extracellular Vesicles’, which …

Compressing light into nanocavities substantially enhances light–matter interactions, which has been a major driver for nanostructured materials research. However, extreme confinement generally comes at the cost of absorption and low resonator quality factors. Here we suggest an alternative optical multimodal confinement mechanism, unlocking the potential of hyperbolic phonon polaritons in isotopically pure hexagonal boron nitride. We produce deep-subwavelength cavities and demonstrate several orders of magnitude improvement in confinement, with estimated Purcell factors exceeding 108 and quality factors in the 50–480 range, values approaching the intrinsic quality factor of hexagonal boron nitride polaritons. Intriguingly, the quality factors we obtain exceed the maximum predicted by impedance-mismatch considerations, indicating that confinement is boosted by higher-order modes. We expect that our …

We present measurements of X-ray Parametric Down Conversion at the Advanced Photon Source synchrotron facility. Using an incoming pump beam at 22 keV, we observe the simultaneous, elastic emission of down-converted photon pairs generated in a diamond crystal. The pairs are detected using high count rate silicon drift detectors with low noise. Production by down-conversion is confirmed by measuring time–energy correlations in the detector signal, where photon pairs within an energy window ranging from 10 to 12 keV are only observed at short time differences. By systematically varying the crystal misalignment and detector positions, we obtain results that are consistent with the constant total of the down-converted signal. Our maximum rate of observed pairs was 130/h, corresponding to a conversion efficiency for the down-conversion process of 5. 3±0. 5× 1 0− 13.

We investigate a quantum walk on a ring represented by a directed triangle graph with complex edge weights and monitored at a constant rate until the quantum walker is detected. To this end, the first hitting time statistics is recorded using unitary dynamics interspersed stroboscopically by measurements, which is implemented on IBM quantum computers with a midcircuit readout option. Unlike classical hitting times, the statistical aspect of the problem depends on the way we construct the measured path, an effect that we quantify experimentally. First, we experimentally verify the theoretical prediction that the mean return time to a target state is quantized, with abrupt discontinuities found for specific sampling times and other control parameters, which has a well-known topological interpretation. Second, depending on the initial state, system parameters, and measurement protocol, the detection probability can be less than one or even zero, which is related to dark-state physics. Both, return-time quantization and the appearance of the dark states are related to degeneracies in the eigenvalues of the unitary time evolution operator. We conclude that, for the IBM quantum computer under study, the first hitting times of monitored quantum walks are resilient to noise. Yet, finite resolution effects lead to new topological, chirality, and broadening effects, which disappear in the asymptotic theory with an infinite number of measurements. Our results point the way for the development of novel quantum walk algorithms that exploit measurement-induced effects on quantum computers.

The majority of human genetic diseases are caused by single nucleotide variants (SNVs) in the genome sequence. Excitingly, new genomic techniques known as base editing have opened efficient pathways to correct erroneous nucleotides. Due to reliance on deaminases, which have the capability to convert A to I(G) and C to U, the direct applicability of base editing might seem constrained in terms of the range of mutations that can be reverted. In this evaluation, we assess the potential of DNA and RNA base editing methods for treating human genetic diseases. Our findings indicate that 62% of pathogenic SNVs found within genes can be amended by base editing; 30% are G>A and T>C SNVs that can be corrected by DNA base editing, and most of them by RNA base editing as well, and 29% are C>T and A>G SNVs that can be corrected by DNA base editing directed to the complementary strand. For each, we …

Second-order superlattices form when moir\'e superlattices of similar dimensions interfere with each other, leading to even larger superlattice periodicities. These crystalline structures have been engineered utilizing two-dimensional (2D) materials such as graphene and hexagonal boron nitride (hBN) under specific alignment conditions. Such specific alignment has shown to play a crucial role in facilitating correlation-driven topological phases featuring the quantized anomalous Hall effect. While signatures of second-order superlattices have been found in transport experiments, any real-space visualization is lacking to date. In this work, we present cryogenic nanoscale photovoltage (PV) measurements that reveal a second-order superlattice in magic-angle twisted bilayer graphene (MATBG) closely aligned to hBN. This is evidenced by long-range periodic photovoltage modulations across the entire sample backed by corresponding electronic transport features. Our theoretical framework shows that small strain- or twist-angle variations can lead to a drastic shift between a local one-dimensional, square or triangular superlattices. Our real-space observations shed new light on the mechanisms responsible for breaking spatial symmetries in TBG and pave an avenue to engineer long-range superlattice structures in 2D materials.

In biological, glassy, and active systems, various tracers exhibit Laplace-like, i.e., exponential, spreading of the diffusing packet of particles. The limitations of the central limit theorem in fully capturing the behaviors of such diffusive processes, especially in the tails, have been studied using the continuous time random walk model. For cases when the jump length distribution is super-exponential, e.g., a Gaussian, we use large deviations theory and relate it to the appearance of exponential tails. When the jump length distribution is sub-exponential the packet of spreading particles is described by the big jump principle. We demonstrate the applicability of our approach for finite time, indicating that rare events and the asymptotics of the large deviations rate function can be sampled for large length scales within a reasonably short measurement time.

Overcoming the diffraction limit is crucial for obtaining high-resolution images and observing fine microstructures. With this conventional difficulty still puzzling us and the prosperous development of wave dynamics of light interacting with gravitational fields in recent years, how spatial curvature affects the diffraction limit is an attractive and important question. Here we investigate the issue of the diffraction limit and optical resolution on two-dimensional curved space—surfaces of revolution (SORs) with constant or variable spatial curvature. We show that the diffraction limit decreases and the resolution is improved on SORs with positive Gaussian curvature, opening a new avenue to super-resolution. The diffraction limit is also influenced by the propagation direction, as well as the propagation distance in curved space with variable spatial curvature. These results provide a possible method to control the optical …

Understanding enzyme mechanisms is essential for unraveling the complex molecular machinery of life. In this review, we survey the field of computational enzymology, highlighting key principles governing enzyme mechanisms and discussing ongoing challenges and promising advances. Over the years, computer simulations have become indispensable in the study of enzyme mechanisms, with the integration of experimental and computational exploration now established as a holistic approach to gain deep insights into enzymatic catalysis. Numerous studies have demonstrated the power of computer simulations in characterizing reaction pathways, transition states, substrate selectivity, product distribution, and dynamic conformational changes for various enzymes. Nevertheless, significant challenges remain in investigating the mechanisms of complex multistep reactions, large-scale conformational changes …

Stretched-exponential relaxation is a widely observed phenomenon found in ordered ferromagnets as well as glassy systems. One modeling approach connects this behavior to a droplet dynamics described by an effective Langevin equation for the droplet radius with an r 2/3 potential. Here, we study a Brownian particle under the influence of a general confining, albeit weak, potential field that grows with distance as a sublinear power law. We find that for this memoryless model, observables display stretched-exponential relaxation. The probability density function of the system is studied using a rate-function ansatz. We obtain analytically the stretched-exponential exponent along with an anomalous power-law scaling of length with time. The rate function exhibits a point of nonanalyticity, indicating a dynamical phase transition. In particular, the rate function is double valued both to the left and right of this point …

We investigate a quantum walk on a ring represented by a directed triangle graph with complex edge weights and monitored at a constant rate until the quantum walker is detected. To this end, the first hitting time statistics is recorded using unitary dynamics interspersed stroboscopically by measurements, which is implemented on IBM quantum computers with a midcircuit readout option. Unlike classical hitting times, the statistical aspect of the problem depends on the way we construct the measured path, an effect that we quantify experimentally. First, we experimentally verify the theoretical prediction that the mean return time to a target state is quantized, with abrupt discontinuities found for specific sampling times and other control parameters, which has a well-known topological interpretation. Second, depending on the initial state, system parameters, and measurement protocol, the detection probability can be less than one or even zero, which is related to dark-state physics. Both, return-time quantization and the appearance of the dark states are related to degeneracies in the eigenvalues of the unitary time evolution operator. We conclude that, for the IBM quantum computer under study, the first hitting times of monitored quantum walks are resilient to noise. Yet, finite resolution effects lead to new topological, chirality, and broadening effects, which disappear in the asymptotic theory with an infinite number of measurements. Our results point the way for the development of novel quantum walk algorithms that exploit measurement-induced effects on quantum computers.