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Axion-modified photon propagator, Coulomb potential, and Lamb shift
摘要： A consistent renormalization of a quantum theory of axion-electrodynamics requires terms beyond the minimal coupling of two photons to a neutral pseudoscalar field. This procedure is used to determine the self-energy operators of the electromagnetic and the axion fields with an accuracy of second-order in the axion-diphoton coupling. The resulting polarization tensor is utilized for establishing the axion-modified Coulomb potential of a static pointlike charge. In connection, the plausible distortion of the Lamb-shift in hydrogenlike atoms is established and the scopes for searching axionlike particles in high-precision atomic spectroscopy and in experiments of Cavendish-type are investigated. Particularly, we show that these hypothetical degrees of freedom are ruled out as plausible candidates for explaining the proton radius anomaly in muonic hydrogen. A certain loophole remains, though, which is linked to the nonrenormalizable nature of axion-electrodynamics.
关键词： axion-electrodynamics,axionlike particles,proton radius anomaly,polarization tensor,renormalization,Lamb-shift,Coulomb potential
更新于2025-09-23 15:23:52
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[IEEE 2018 26th International Conference on Geoinformatics - Kunming (2018.6.28-2018.6.30)] 2018 26th International Conference on Geoinformatics - Multilevel Solar Potential Analysis of Building Based on Ubiquitous Point Clouds
摘要： Solar potential analysis is essential for Building Information Modeling (BIM) applications, like photovoltaic installation. The estimation of solar potential on rooftops has been widely discussed, whereas the study on fa?ade is still limited. Benefit from the development of various sensors, ubiquitous point clouds are now widely and easily captured by photogrammetry, laser scanning or other technologies, to represent the building geometry. This paper proposes a method for solar potential analysis on both rooftops and fa?ades, using ubiquitous point cloud collected by Unmanned Aerial Vehicle (UAV) and Terrestrial Laser Scanning (TLS). One building with different orientations is selected for the case study. Results show that the proposed method is valid for multilevel solar potential analysis of buildings.
关键词： laser scanning,solar potential,ubiquitous point cloud,Building Information Modeling (BIM)
更新于2025-09-23 15:23:52
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<i>N</i> -Arylphenothiazines as strong donors for photoredox catalysis – pushing the frontiers of nucleophilic addition of alcohols to alkenes
摘要： A new range of N-phenylphenothiazine derivatives was synthesized as potential photoredox catalysts to broaden the substrate scope for the nucleophilic addition of methanol to styrenes through photoredox catalysis. These N-phenylphenothiazines differ by their electron-donating and electron-withdrawing substituents at the phenyl group, covering both, σ and π-type groups, in order to modulate their absorbance and electrochemical characteristics. Among the synthesized compounds, alkylaminylated N-phenylphenothiazines were identified to be highly suitable for photoredox catalysis. The dialkylamino substituents of these N-phenylphenothiazines shift the estimated excited state reduction potential up to ?3.0 V (vs SCE). These highly reducing properties allow the addition of methanol to α-methylstyrene as less-activated substrate for this type of reaction. Without the help of an additive, the reaction conditions were optimized to achieve a quantitative yield for the Markovnikov-type addition product after 20 h of irradiation.
关键词： redox potential,photochemistry,addition,photoredox catalysis,phenothiazine
更新于2025-09-23 15:22:29
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A chemogenetic approach for optical monitoring of voltage in neurons
摘要： Optical monitoring of neuronal voltage using fluorescent indicators is a powerful approach for interrogation of the cellular and molecular logic of the nervous system. Here we describe a Semisynthetic Tethered Voltage Indicator (STeVI1) based upon Nile Red that displays voltage sensitivity when genetically targeted to neuronal membranes. This environmentally sensitive probe allows for wash-free imaging and faithfully detects supra- and subthreshold activity in neurons.
关键词： membrane potential probes,voltage imaging,genetic targeting,protein tags,fluorogenic probes
更新于2025-09-23 15:22:29
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Frozen Gaussian approximation for high frequency wave propagation in periodic media
摘要： Propagation of high-frequency wave in periodic media is a challenging problem due to the existence of multiscale characterized by short wavelength, small lattice constant and large physical domain size. Conventional computational methods lead to extremely expensive costs, especially in high dimensions. In this paper, based on Bloch decomposition and asymptotic analysis in the phase space, we derive the frozen Gaussian approximation for high-frequency wave propagation in periodic media and establish its converge to the true solution. The formulation leads to ef?cient numerical algorithms, which are presented in a companion paper [SIAM J. Sci. Comput. 38 (2016), A2440–A2463].
关键词： lattice potential,high-frequency wave propagation,Bloch decomposition,Frozen Gaussian approximation
更新于2025-09-23 15:22:29
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Quantifying Double-Layer Potentials at Liquid–Gas Interfaces from Vibrational Sum-Frequency Generation
摘要： Vibrational sum-frequency generation (SFG) spectroscopy is demonstrated as a fast method to quantify variations of the electric double-layer potential ?0 at liquid?gas interfaces. For this, mixed solutions of nonionic tetraethyleneglycol-monodecylether (C10E4) and cationic hexadecyltrimethylammonium bromide (C16TAB) surfactants were investigated using SFG spectroscopy and a thin-film pressure balance (TFPB). Derjaguin?Landau?Verwey?Overbeek analysis of disjoining pressure isotherms obtained with the TFPB technique provides complementary information on ?0, which we apply to validate the results from SFG spectroscopy. By using a single ?0 value, we can disentangle χ(2) and χ(3) contributions to the O?H stretching modes of interfacial water molecules in the SFG spectra. Having established the latter, we show that unknown double-layer potentials at the liquid?gas interface from solutions with different C16TAB/C10E4 mixing ratios can be obtained from an analysis of SFG spectra and are in excellent agreement with the complementary results from the TFPB technique.
关键词： disjoining pressure,Vibrational sum-frequency generation,electric double-layer potential,thin-film pressure balance,liquid?gas interfaces,surfactants
更新于2025-09-23 15:22:29
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Cardiac Electrophysiological Effects of Light-Activated Chloride Channels
摘要： During the last decade, optogenetics has emerged as a paradigm-shifting technique to monitor and steer the behavior of specific cell types in excitable tissues, including the heart. Activation of cation-conducting channelrhodopsins (ChR) leads to membrane depolarization, allowing one to effectively trigger action potentials (AP) in cardiomyocytes. In contrast, the quest for optogenetic tools for hyperpolarization-induced inhibition of AP generation has remained challenging. The green-light activated ChR from Guillardia theta (GtACR1) mediates Cl?-driven photocurrents that have been shown to silence AP generation in different types of neurons. It has been suggested, therefore, to be a suitable tool for inhibition of cardiomyocyte activity. Using single-cell electrophysiological recordings and contraction tracking, as well as intracellular microelectrode recordings and in vivo optical recordings of whole hearts, we find that GtACR1 activation by prolonged illumination arrests cardiac cells in a depolarized state, thus inhibiting re-excitation. In line with this, GtACR1 activation by transient light pulses elicits AP in rabbit isolated cardiomyocytes and in spontaneously beating intact hearts of zebrafish. Our results show that GtACR1 inhibition of AP generation is caused by cell depolarization. While this does not address the need for optogenetic silencing through physiological means (i.e., hyperpolarization), GtACR1 is a potentially attractive tool for activating cardiomyocytes by transient light-induced depolarization.
关键词： heart,action potential,zebrafish,optogenetics,GtACR1,natural anion channelrhodopsin
更新于2025-09-23 15:22:29
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Corrosion Resistance of Aluminum against Acid Activation: Impact of Benzothiazole-Substituted Gallium Phthalocyanine
摘要： This study describes the adsorption behavior of organic inhibitors at the aluminum-HCl solution interface and their corrosion inhibition performance. The organic inhibitors employed are: 4-(benzo [d]thiazol-2ylthio)phthalonitrile (BTThio) and tetrakis[(benzo[d]thiazol-2-yl-thio)phthalocyaninato]gallium(III) chloride (ClGaBTThioPc). The corrosion behavior of these inhibitors is investigated using electrochemical and computational techniques. Open circuit potential results reveal predominant cathodic character for the mechanism of aluminum corrosion inhibition by the inhibitors. Inhibition efficiency values from potentiodynamic polarization measurements increase from 46.9 to 70.8% for BTThio and 59.7 to 81.0% for ClGaBTThioPc within the concentration range of 2 to 10 μM. Scanning electron microscopy (SEM) measurements reveal protection of the metal surface from acid attack, in the presence of the inhibitors and energy dispersive X-ray (EDX) measurements show that the most probable way by which the inhibitors protect the metal surface would be by shielding it from the corrosion attacks of Cl? from the acid. Quantum chemical parameters corroborate well with experimental findings.
关键词： open circuit potential,cyclic voltammetry,potentiodynamic polarization,corrosion inhibition
更新于2025-09-23 15:22:29
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Exploring Potential Energy Surfaces for Aggregation‐Induced Emission ‐ from Solution to Crystal
摘要： Aggregation-induced emission (AIE) is a phenomenon where non-luminescent compounds in solution become strongly luminescent in aggregate and solid phase. It provides a fertile ground for luminescent applications that has rapidly developed in the last 15 years. In this review, we focus on the contributions of theory and computations to understanding the molecular mechanism behind it. Starting from initial models, such as restriction of intramolecular rotations (RIR), and the calculation of non-radiative rates with Fermi’s golden rule (FGR), we center on studies of the global excited-state potential energy surfaces that have provided the basis for the restricted access to a conical intersection (RACI) model. In this model, which has been shown to apply for a diverse group of AIEgens, the lack of fluorescence in solution comes from radiationless decay at a CI in solution that is hindered in the aggregate state. We also highlight how intermolecular interactions modulate the photophysics in the aggregate phase, in terms of fluorescence quantum yield and emission color.
关键词： intermolecular interactions,aggregation-induced emission,conical intersections,potential energy surfaces
更新于2025-09-23 15:22:29
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Structural Coloration with Nonclose-Packed Array of Bidisperse Colloidal Particles
摘要： Colloidal crystals and glasses have their own photonic effects. Colloidal crystals show high reflectivity at narrowband, whereas colloidal glasses show low reflectivity at broadband. To compromise the opposite optical properties, a simple means is suggested to control the colloidal arrangement between crystal and glass by employing two different sizes of silica particles with repulsive interparticle potential. Monodisperse silica particles with repulsive potential spontaneously form crystalline structure at volume fraction far below 0.74. When two different sizes of silica particles coexist, the arrangement of silica particles is significantly influenced by two parameters: size contrast and mixing ratio. When the size contrast is small, a long-range order is partially conserved in the entire mixing ratio, resulting in a pronounced reflectance peak and brilliant structural color. When the size contrast is large, the long-range order is rapidly reduced along with mixing ratio. Nevertheless, a short-range order survives, which causes low reflectivity at a broad wavelength, developing faint structural colors. These findings offer an insight into controlling the colloidal arrangements and provide a simple way to tune the optical property of colloidal arrays for structural coloration.
关键词： colloidal arrays,colloids,mechanochromism,structural colors,repulsive potential
更新于2025-09-23 15:22:29