Redox-Transition from Irreversible to Reversible Vitamin C by Pore Confinement in Microporous Carbon Network

Enhancement of redox-reversibility in electroactive species has been studied because of fundamental interest and their importance for energy storage systems. Various electroactive molecules suffer from redox-irreversible behavior, and this is a critical reason for their exclusion as redox electrolytes in energy storage systems. In this article, we fully demonstrated that ascorbic acid (ASC), which is an abundant but redox-irreversible molecule, can become redox-reversible when it is confined in microporous carbon regimes. From a theoretical perspective, redox-reversibility in an electrochemical reaction coupled with an irreversible chemical process can be greatly enhanced due to kinetic acceleration toward the inverse direction of the chemical reaction by accumulation of products in the nanoconfined regime. However, the kinetic acceleration in a nanoconfined domain shows limitations for enhancing the redox-reversibility, which indicates that stabilization of the species undergoing an irreversible chemical process is another important factor for redox-reversibility enhancement. The origin of nanoporous confinement of ASC and its enhanced redox-reversibility was rationalized by molecular dynamics simulations. We found that ASC-clusters of a fully protonated ASC and its conjugated base formed inside carbon pores, which would be a main driving force for its confinement in microporous carbon networks. Lastly, we demonstrated a prototype energy storage device using redox-reversible ASC in microporous carbon as the half electrode, which shows the feasibility of ASC as a possible redox electrolyte in an aqueous energy storage system.N

Few-Shot Anomaly Detection via Personalization

Even with a plenty amount of normal samples, anomaly detection has been considered as a challenging machine learning task due to its one-class nature, i. e., the lack of anomalous samples in training time. It is only recently that a few-shot regime of anomaly detection became feasible in this regard, e. g., with a help from large vision-language pre-trained models such as CLIP, despite its wide applicability. In this paper, we explore the potential of large text-to-image generative models in performing few-shot industrial anomaly detection. Specifically, recent text-to-image models have shown unprecedented ability to generalize from few images to extract their common and unique concepts, and even encode them into a textual token to “personalize” the model: so-called textual inversion. Here, we question whether this personalization is specific enough to discriminate the given images from their potential anomalies, which are often, e. g., open-ended, local, and hard-to-detect. We observe that standard textual inversion exhibits a weaker understanding in localized details within objects, which is not enough for detecting industrial anomalies accurately. Thus, we explore the utilization of model personalization to address anomaly detection and propose Anomaly Detection via Personalization (ADP). ADP enables extracting fine-grained local details shared in the images with simple-yet an effective regularization scheme from the zero-shot transferability of CLIP. We also propose a self-tuning scheme to further optimize the performance of our detection pipeline, leveraging synthetic data generated from the personalized generative model. Our experiments show that the proposed inversion scheme could achieve state-of-the-art results on two industrial anomaly benchmarks, MVTec-AD and VisA, in the regime of few normal samples

LOW-LYING ELECTRONICALLY EXCITED-STATES OF C-60 AND C-70 AND MEASUREMENT OF THEIR PICOSECOND TRANSIENT ABSORPTION IN SOLUTION

Low-lying electronically excited states of C60 and C70 were identified in picosecond transient absorption measurements extending in wavelength down to 1000 nm. Spectral features in the near-infrared region were found to be significantly different from the results of previous studies. The lifetimes for S1 states of C60 and C70 Were determined to be 1.3+/-0.2 ns and 0.7+/-0.05 ns, respectively. A simple energy diagram for electronic states of C60 and C70 is presented

Unlocking the benefits of glassy-like carbon synthesis: Direct immobilization of single Ni sites for robust electrochemical CO2 reduction reaction

Stable electrodes are crucial for the practical applications of electrochemical systems. In this study, we report a simple method for synthesizing three-dimensional glassy-like carbon (3D·GC) on an alumina substrate through pyrolysis of benzyl alcohol and applying it to electrocatalytic reactions. Given its distinctive 3D morphology and stability in aqueous solution, the 3D·GC electrode exhibits significantly higher electrocatalytic activity than the commercial GC. Moreover, the rough surface of the 3D·GC electrode is favorable for direct immobilization of catalytic sites, such as metals (Au and Ag) and single-atom catalysts. The developed method for immobilizing single Ni sites is successfully applied to the 3D·GC electrode, resulting in the Ni SAC-3D·GC electrode that exhibits high CO selectivity and durability for electrochemical CO2 reduction. The Faradaic efficiency of CO is over 90% across a wide potential range. Due to direct immobilization, the Ni SAC-3D·GC electrode shows remarkable stability even after multiple reuse cycles, indicating its potential for long-term electrocatalytic applications. To gain an understanding of the mechanism underlying the high CO selectivity during CO2 reduction, the theoretical interactions between the individual Ni sites and the carbon substrate are explored. This theoretical analysis highlights the crucial role of the carbon substrate in stabilizing the COOH intermediate for electrochemical CO2 reduction under neutral conditions

TEMPERATURE AND SIZE DEPENDENT EXCITONIC RELAXATION PROCESS IN GAAS/ALGAAS QUANTUM-WELLS

Temperature dependent risetimes of exciton luminescence in different size quantum wells are obtained by using time correlated single photon counting technique. The decreasing rate of risetimes with increasing temperature, the photoluminescence spectra, and the temperature dependent decay times consistently show that excitons are likely to be localized on interface defects as the well size decreases

Unraveling the Simultaneous Enhancement of Selectivity and Durability on Single-Crystalline Gold Particles for Electrochemical CO2 Reduction

Electrochemical carbon dioxide reduction is a mild and eco-friendly approach for CO2 mitigation and producing value-added products. For selective electrochemical CO2 reduction, single-crystalline Au particles (octahedron, truncated-octahedron, and sphere) are synthesized by consecutive growth and chemical etching using a polydiallyldimethylammonium chloride (polyDDA) surfactant, and are surface-functionalized. Monodisperse, single-crystalline Au nanoparticles provide an ideal platform for evaluating the Au surface as a CO(2)reduction catalyst. The polyDDA-Au cathode affords high catalytic activity for CO production, with >90% Faradaic efficiency over a wide potential range between -0.4 and -1.0 V versus RHE, along with high durability owing to the consecutive interaction between dimethylammonium and chloride on the Au surface. The influence of polyDDA on the Au particles, and the origins of the enhanced selectivity and stability are fully investigated using theoretical studies. Chemically adsorbed polyDDA is consecutively affected the initial adsorption of CO2 and the stability of the *CO2, *COOH, and *CO intermediates during continuous CO2 reduction reaction. The polyDDA functionalization is extended to improving the CO Faradaic efficiency of other metal catalysts such as Ag and Zn, indicating its broad applicability for CO2 reduction