Charge Moment Research Articles

Influence of hydrophobicity on the antimicrobial activity of helical antimicrobial peptides: a study focusing on three mastoparans.

Hydrophobicity is crucial for the interaction between amphipathic antimicrobial peptides and microbial pathogens. However, it is difficult to fully understand the impact of this factor because the biological functions are also influenced by other structural properties, including peptide length, net charge, hydrophilicity, secondary structure, and hydrophobic moment. This study compares three natural antimicrobial peptides-mastoparan C, mastoparan-AF, and mastoparan L-where hydrophobicity varies but other structural features remain nearly identical. Mastoparan C, the most hydrophobic peptide, displays the highest helical content and hemolytic activity, whereas mastoparan-AF, with slightly lower hydrophobicity, demonstrates superior selectivity. In contrast, mastoparan L, the least hydrophobic peptide, exhibits the weakest antimicrobial potency and lowest hemolytic activity, despite showing the least self-assembly. Overall, this study suggests that optimal hydrophobicity, rather than the highest value, enhances antimicrobial efficacy while minimizing hemolytic activity.

Non-equilibrium dynamics of symmetry-resolved entanglement and entanglement asymmetry: exact asymptotics in Rule 54*

Abstract Symmetry resolved entanglement and entanglement asymmetry are two measures of quantum correlations sensitive to symmetries of the system. Here we discuss their non-equilibrium dynamics in the Rule 54 cellular automaton, a simple, yet interacting, integrable model. Both quantities can be expressed in terms of the more analytically tractable ‘charged moments’, i.e. traces of powers of a suitably deformed density matrix, via a replica trick. We express them in terms of a tensor network, which we contract in space using a system of local algebraic relations. This gives the asymptotic form for the charged moments, valid in the regime of large but finite time that is shorter than all the relevant subsystem sizes. In this regime the charge moments decay exponentially with the rate given by the leading solution to a cubic equation.

Density Functional Theory Study on Screening and Key Metrics for Non-metallic Oxygen Reduction Catalysts.

This study systematically investigates the oxygen reduction reaction (ORR) catalytic activity of graphene doped with various non-metallic impurities. The non-metal elements include boron (B), silicon (Si), nitrogen (N), phosphorus (P), arsenic (As), oxygen (O), sulfur (S), selenium (Se), tellurium (Te), fluorine (F), chlorine (Cl), bromine (Br), and iodine (I). We found that adsorbates tend to adsorb on positively charged impurity atoms. We identified several substrates with good catalytic activity, all of which have an ORR overpotential of around 0.6 V. We further verified the thermodynamic stability of these substrates and found them to be very stable. We summarized the optimal adsorption energies for ORR intermediates O2H, O, and OH to be -1.9, -3.4, and -2.4 eV, respectively, and validated their reasonableness. Finally, we used simple linear functions to fit the relationship between the adsorption energies of O2H, O, and OH and the charge and magnetic moment of the adsorption site atoms. This model can roughly predict the ORR catalytic activity of doped graphene, facilitating the faster screening of excellent ORR catalysts.

Electric-Field Control of the Local Thermal Conductivity in Charge Transfer Oxides.

Phonons, the collective excitations responsible for heat transport in crystalline insulating solids, lack electric charge or magnetic moment, which complicates their active control via external fields. This presents a significant challenge in designing thermal equivalents of basic electronic circuit elements, such as transistors or diodes. Achieving these goals requires precise and reversible modification of thermal conductivity in materials. In this work, the continuous tuning of local thermal conductivity in charge-transfer SrFeO3-x and La0.6Sr0.4CoO3-x oxides using a voltage-biased Atomic Force Microscopy (AFM)tip at room temperature is demonstrated. This method allows the creation of micron-sized domains with well-defined thermal conductivity, achieving reductions of up to 50%, measured by spatially resolved Frequency Domain Thermoreflectance (FDTR). By optimizing the oxide's chemical composition, the thermal states remain stable under normal atmospheric conditions but can be reverted to their original values through thermal annealing in air. A comparison between Mott-Hubbard and charge-transfer oxides reveals the critical role of redox-active lattice oxygen in ensuring full reversibility of the process. This approach marks a significant step toward fabricating oxide-based tunable microthermal resistances and other elements for thermal circuits.

Theoretically grounded approaches to account for polarization effects in fixed-charge force fields.

Non-polarizable, or fixed-charge, force fields are the workhorses of most molecular simulation studies. They attempt to describe the potential energy surface (PES) of the system by including polarization effects in an implicit way. This has historically been done in a rather empirical and ad hoc manner. Recent theoretical treatments of polarization, however, offer promise for getting the most out of fixed-charge force fields by judicious choice of parameters (most significantly the net charge or dipole moment of the model) and application of post facto polarization corrections. This Perspective describes these polarization theories, namely the "halfway-charge" theory and the molecular dynamics in electronic continuum theory, and shows that they lead to qualitatively (and often, quantitatively) similar predictions. Moreover, they can be reconciled into a unified approach to construct a force field development workflow that can yield non-polarizable models with charge/dipole values that provide an optimal description of the PES. Several applications of this approach are reviewed, and avenues for future research are proposed.

A common framework for fermion mass hierarchy, leptogenesis and dark matter

In this work, we explore an extension of the Standard Model designed to elucidate the fermion mass hierarchy, account for the dark matter relic abundance, and explain the observed matter-antimatter asymmetry in the universe. Beyond the Standard Model particle content, our model introduces additional scalars and fermions. Notably, the light active neutrinos and the first two generations of charged fermions acquire masses at the one-loop level. The model accommodates successful low-scale leptogenesis, permitting the mass of the decaying heavy right-handed neutrino to be as low as 10 TeV. We conduct a detailed analysis of the dark matter phenomenology and explore various interesting phenomenological implications. These include charged lepton flavor violation, muon and electron anomalous magnetic moments, constraints arising from electroweak precision observables, and implications for collider experiments.

Electric dipole moments of charged leptons in models with pseudo-Dirac sterile fermions

In this work, we address the impact of a small lepton number violation on charged lepton electric dipole moments — EDMs. Low-scale seesaw models protected by lepton number symmetry and leading to pseudo-Dirac pairs in the neutrino heavy spectrum provide a natural explanation for the smallness of neutrino masses with potentially testable consequences. Among which, it was thought that the small mass gap in each pair of pseudo-Dirac neutrinos may induce important contribution to the charged lepton EDMs. Recently, it has been shown that the contribution from some of the Feynman diagrams to charged lepton EDMs exactly cancel by virtue of the Ward-Takahashi identity in quantum electrodynamics. We thus consider here the Standard Model minimally extended with pairs of pseudo-Dirac sterile fermions and derive the complete analytical formula at two loops for the charged lepton EDMs. In addition, we numerically evaluate the order of the predicted EDMs consistent with the experimental bounds and constraints such as neutrino oscillation data, charged lepton flavour violating processes, sterile neutrino direct searches, meson decays, sterile neutrino decays, and cosmological and astrophysical observations. We find that, in the minimal setup accommodating neutrino data (masses and mixings) with only two pseudo-Dirac pairs, the predicted electron EDM is O10−36\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{O}\\left({10}^{-36}\\right) $$\\end{document}e cm, at most, which is much smaller than the current experimental bound and even future sensitivity. Hopefully, the electron EDM might reach future sensitivity, once extra pseudo-Dirac neutrinos are taken into account. The analytical formulae we derive are generic to any model involving pseudo-Dirac pairs in the heavy neutrino spectrum.

An approximate Kerr–Newman-like metric endowed with a magnetic dipole and mass quadrupole

Approximate all-terrain spacetimes for astrophysical applications are presented. The metrics possess five relativistic multipole moments, namely, mass, rotation, mass quadrupole, charge, and magnetic dipole moment. All these spacetimes approximately satisfy the Einstein–Maxwell field equations. The first metric is generated using the Hoenselaers–Perjés method from given relativistic multipoles. The second metric is a perturbation of the Kerr–Newman metric, which makes it a relevant approximation for astrophysical calculations. The last metric is an extension of the Hartle–Thorne metric that is important for obtaining internal models of compact objects perturbatively. The electromagnetic field is calculated using Cartan forms for locally non-rotating observers. These spacetimes are relevant for inferring properties of compact objects from astrophysical observations. Furthermore, the numerical implementations of these metrics are straightforward, making them versatile for simulating potential astrophysical applications.

The Hermeneutics of Iberian Identity: Reassessing the Stability of Signs in the Theatrical Works of Juan del Encina

The end of the fifteenth century was a charged moment in Iberia as authors grappled with shifting social categories in the decades leading up to and following the Expulsion of the Jews. Two of Juan del Encina short theatrical églogas are quite suggestive for reassessing the hermeneutics of Iberian identities. The humour serves to reassure the audience that self-transformation is a ridiculous prospect confined to the stage. Nevertheless, the exploration of themes of identity shifts underscores the collective anxiety that social transformations might indeed be occurring in contemporary Castilian society and need to be dismissed with humour.

Entangled multiplets, asymmetry, and quantum Mpemba effect in dissipative systems

Recently, the entanglement asymmetry emerged as an informative tool to understand dynamical symmetry restoration in out-of-equilibrium quantum many-body systems after a quantum quench. For integrable systems the asymmetry can be understood in the space-time scaling limit via the quasiparticle picture, as it was pointed out in Ares et al (2023 Nat. Commun. 14 2036) . However, a quasiparticle picture for quantum quenches from generic initial states was still lacking. Here we conjecture a full-fledged quasiparticle picture for the charged moments of the reduced density matrix, which are the main ingredients to construct the asymmetry. Our formula works for quenches producing entangled multiplets of an arbitrary number of excitations. We benchmark our results in the XX spin chain. First, by using an elementary approach based on the multidimensional stationary phase approximation we provide an ab initio rigorous derivation of the dynamics of the charged moments for the quench treated in Ares et al (2023 SciPost Phys. 15 089). Then, we show that the same results can be straightforwardly obtained within our quasiparticle picture. As a byproduct of our analysis, we obtain a general criterion ensuring a vanishing entanglement asymmetry at long times. Next, by using the Lindblad master equation, we study the effect of gain and loss dissipation on the entanglement asymmetry. Specifically, we investigate the fate of the so-called quantum Mpemba effect (QME) in the presence of dissipation. We show that dissipation can induce QME even if unitary dynamics does not show it, and we provide a quasiparticle-based interpretation of the condition for the QME.

Relationship Between Biophysical Properties of Antimicrobial Peptides (AMPs) and their Associated Drug Efficacies

Antibiotic resistance is a growing global health threat. One consequence is that patients with cystic fibrosis (CF) are prone to developing antibiotic resistant lung infections caused by multiple strains of bacteria, including Pseudomonas aeruginosa. Due to the limited number of treatment options for patients with chronic antibiotic resistant infections, there is a need for finding new antibiotics that allow for effective eradication of bacterial infections, such as those in the CF lung. Many antimicrobial peptides (AMPs) have been annotated in databases and are considered as potential alternatives for current antibiotics. However, in many instances, the suitability of AMPs as drug molecules has not been extensively explored. Here, we propose that certain molecular properties of AMPs favor high antibiotic efficacy. Using information from AMP databases, we combined statistical analyses and machine learning techniques to identify relationships between various biophysical properties of AMPs and their drug efficacies. Analyses from classification and regression trees (CART) and random forests suggest that net charge and maximum average hydrophobic moment are the most important properties in determining if a peptide is useful against P. aeruginosa infections in CF patients. Maximum average hydrophobic residue, average alpha helix propensity score, hydrophobic proportion, and peptide length still contribute to this determination but to lesser degrees. Cation-pi interactions, on the other hand, do not appear to factor into this decision at all. Based on these properties, our current work is focused on designing and experimentally testing new peptides that may have activity against P. aeruginosa infections.

DFT/TDDFT calculations of geometry optimization, electronic structure and spectral properties of clevudine and telbivudine for treatment of chronic hepatitis B

Chronic hepatitis B remains a worldwide health concern. Presently, many drugs, such as Clevudine and Telbivudine, are recommended for the treatment of chronic hepatitis B disease. For this purpose, the quantum chemical analysis of ELUMO-HOMO (Egap), ionization potential (IP), electron affinity (EA), electronegativity (EN), chemical hardness (η), chemical potential (μ), chemical softness (S), electrophilicity index (ω), electron accepting capability (ω+), electron-donating capability (ω-), Nucleophilicity index (N), additional electronic charge (∆Nmax), Optical softness (σ0) and Dipole Moment, IR and UV–Vis spectra, molecular electrostatic potential (MEP) profile, Mulliken charge analysis, natural bond orbital (NBO) were examined in this study. The dipole moment of the compounds suggests their binding pose and predicted binding affinity. The electrophilic and nucleophilic regions were identified, and techniques such as NBO, UV–Vis, and IR were used to gain insights into the molecular structure, electronic transitions, and potential drug design for Hepatitis B treatment. Calculations for this study were carried out using the Gaussian 09 program package coupled with the DFT/TDDFT technique. The hybrid B3LYP functional method and the 6-311++G(d, p) basis set were used for the calculations.

Rényi entanglement asymmetry in ( 1+1 )-dimensional conformal field theories

In this paper, we consider the Rényi entanglement asymmetry of excited states in the (1+1) dimensional free compact boson conformal field theory (CFT) at equilibrium. We obtain a universal CFT expression written by correlation functions for the charged moments via the replica trick. We provide detailed analytic computations of the second Rényi entanglement asymmetry in the free compact boson CFT for excited states Ψ=Vβ+V−β and Φ=Vβ+J with Vβ and J=i∂ϕ being the vertex operator and current operator, respectively. We make numerical tests of the universal CFT computations using the XX spin chain model. Taking the non-Hermite fake reduced density matrices into consideration, we propose an effective way to test them numerically, which can be applied to other excited states. The CFT predictions are in perfect agreement with the exact numerical calculations. Published by the American Physical Society 2024

Experimental studies on noncentrosymmetric Nd3Se4: Strongly correlated noncollinear ferromagnet

We have synthesized polycrystalline Nd3Se4 by the solid state sealed tube reaction route followed by structural characterization and magnetic property measurements. The temperature-dependent magnetization studies reveal the existence of competing magnetic interactions below the ferromagnetic ordering (TC ≈ 48.4 K). The observation of hysteresis in the isothermal magnetization M(H) data with the coercive field of ≈ 0.25 T at 2 K indicates dominant ferromagnetic interactions in the applied field. The nonsaturating behavior of M(H) data at higher applied field and kinks in corresponding dM/dHvs. H plots suggest the coexistence of multiple magnetic interactions at low temperatures. Using the M(T,H=2 T) data, the Rhodes-Wohlfarth ratio (qc/qs) has been estimated to be ≈ 3.6, which supports the itinerant magnetism in Nd3Se4. These competing interactions have been further investigated by AC-susceptibility measurements at various excitation frequencies. The χ′ reduces drastically with an increase in the applied DC field, as observed from isothermal field-dependent AC-χ studies. Additionally, the strong correlation between delocalized charge and localized magnetic moments is evident from ρ(T) measurements at H = 0 and 5 T. The ρ(T,H=0 T) data shows a clear drop having quadratic temperature dependence, below TC. Furthermore, the inter-dependence between electrical transport and magnetism has been established firmly through negative magnetoresistance, in which the maxima correspond to the coercive field obtained from M(H) data.

Symmetry resolution of the computable cross-norm negativity of two disjoint intervals in the massless Dirac field theory

We investigate how entanglement in the mixed state of a quantum field theory can be described using the cross-computable norm or realignment (CCNR) criterion, employing a recently introduced negativity. We study its symmetry resolution for two disjoint intervals in the ground state of the massless Dirac fermion field theory, extending previous results for the case of adjacent intervals. By applying the replica trick, this problem boils down to computing the charged moments of the realignment matrix. We show that, for two disjoint intervals, they correspond to the partition function of the theory on a torus with a non-contractible charged loop. This confers a great advantage compared to the negativity based on the partial transposition, for which the Riemann surfaces generated by the replica trick have higher genus. This result empowers us to carry out the replica limit, yielding analytic expressions for the symmetry-resolved CCNR negativity. Furthermore, these expressions provide also the symmetry decomposition of other related quantities such as the operator entanglement of the reduced density matrix or the reflected entropy.

Single-atom catalytic N2 fixation with integrated descriptors on a novel π-π conjugated graphitic carbon nitride (g-C13N15) platform obtained by self-doping design: Prediction of ultrahigh activity and desirable selectivity

Great enthusiasm in nitrogen reduction reaction (NRR) towards the robust design of efficient catalysts is being stimulated by a promising active moiety featured by metal-Nx, yet tackling the activity and selectivity dilemmas remains one of the most urgent and challenging tasks. Herein, based on a self-doping strategy and first-principles calculations, an emerging and stable graphitic carbon nitride, g-C13N15, is rationally proposed for the first time, and TM@g-C13N15 (TM = from Ti to Au) single-atom catalysts benefiting from delocalized π−π conjugated interactions between substituted C3N3 rings toward NRR are constructed. High-throughput “Four-Step” screening strategy helps Re@g-C13N15 stand out from 23 TM-centers quickly since the binding strength of the target *N2H and *NH2 adsorbates can be manipulated by Re to compromise. First-principles calculations reveal that Re@g-C13N15 possesses satisfactory selectivity and impressively, miserly energy consumption with a low limiting potential of −0.20/-0.31 V for side-on/end-on N2-adsorption. Also, good thermodynamic stability, large Re-diffusion barrier, outstanding electrochemical durability, and facile synthesis for Re@g-C13N15 ensure its implementations in ambient conditions. Particularly, good linear relationships between descriptors (ICOHP, Bader charge, bond length, d-band center, and spin moment) are established to describe/explain intrinsic activity trends/mechanism, bridging the relation between the intrinsic property and activity.

Multi-charged moments and symmetry-resolved Rényi entropy of free compact boson for multiple disjoint intervals

We study multi-charged moments and symmetry-resolved Rényi entropy of free compact boson for multiple disjoint intervals. The Rényi entropy evaluation involves computing the partition function of the theory on Riemann surfaces with genus g > 1. This makes Rényi entropy sensitive to the local conformal algebra of the theory. The free compact boson possesses a global U(1) symmetry with respect to which we resolve Rényi entropy. The multi-charged moments are obtained by studying the correlation function of flux-generating vertex operators on the associated Riemann surface. Symmetry-resolved Rényi entropy is then obtained from the Fourier transforms of the charged moments. Rényi entropy is shown to have the familiar equipartition into local charge sectors upto the leading order. The multi-charged moments are also essential in studying the symmetry resolution of mutual information. The multi-charged moments of the self-dual compact boson and massless Dirac fermion are also shown to match for the cases when the associated reduced density moments are known to be the same. Finally, we numerically check our results against the tight-binding model.

A self-powered droplet sensor based on a triboelectric nanogenerator toward the concentration of green tea polyphenols.

Self-powered liquid droplet sensors based on triboelectric nanogenerators have attracted extensive attention in the field of biochemical sensing applications. Numerous research studies have investigated the effects of factors such as molecular species, molecular concentration, molecular charge, and molecular dipole moment in solution on the output electrical signals of the sensor. In this study, we prepared a self-powered droplet sensor using conductive copper film tape, polytetrafluoroethylene, and conductive aluminum foil tape. The sensor can continuously output pulsed electrical signals with minimal environmental impact. In comparison with other types of sensors, this sensor boasts a rapid response time of 10 ms and excellent sensitivity. The relationship between the friction-induced output current and voltage of the droplets and the concentration of green tea polyphenols (GTPs) was studied using the self-powered liquid droplet sensor with five different green tea samples. It was found that GTPs were the main factor contributing to the changes in output electrical signals in green tea water droplets. Fluorescence spectroscopy was used to reveal that the magnitude of the output current was inversely proportional to the concentration of GTPs in green tea. These results demonstrate the potential application of self-powered liquid droplet sensors in biochemical sensing applications based on concentration-dependent output signals.

Theoretical Study on ORR/OER Bifunctional Catalytic Activity of Axial Functionalized Iron Polyphthalocyanine.

Designing efficient ORR/OER bifunctional electrocatalysts is very significant for reducing energy consumption and environmental protection. Hence, we studied the ORR/OER bifunctional catalytic activity of iron polyphthalocyanine (FePPc) coordinated by a series of axial ligands which has different electronegative coordination atom (FePPc-L) (L = -CN, -SH, -SCH3, -SC2H5, -I, -Br, -NH2, -Cl, -OCH3, -OH, and -F) in alkaline medium by DFT calculations. Among all FePPc-L, FePPc-CN, FePPc-SH, FePPc-SCH3, and FePPc-SC2H5 exhibit excellent ORR/OER bifunctional catalytic activities. Their ORR/OER overpotential is 0.256 V/0.234 V, 0.278 V/0.256 V, 0.280 V/0.329 V, and 0.290 V/0.316 V, respectively, which are much lower than that of the FePPc (0.483 V/0.834 V). The analysis of the electronic structure of the above catalysts shows that the electronegativity of the coordination atoms in the axial ligand is small, resulting in less distribution of dz2, dyz, and dxz orbitals near Ef, weak orbital polarization, small charge and magnetic moment of the central Fe atom, and weak adsorption strength for *OH. All these prove that the introduction of axial ligands with appropriate electronegativity coordinating atoms can adjust the adsorption of catalyst to intermediates and modify the ORR/OER bifunctional catalytic activities. This is an effective strategy for designing efficient ORR/OER bifunctional electrocatalysts.

Symmetry-resolved entanglement entropy, spectra & boundary conformal field theory

We perform a comprehensive analysis of the symmetry-resolved (SR) entanglement entropy (EE) for one single interval in the ground state of a 1 + 1D conformal field theory (CFT), that is invariant under an arbitrary finite or compact Lie group, G. We utilize the boundary CFT approach to study the total EE, which enables us to find the universal leading order behavior of the SREE and its first correction, which explicitly depends on the irreducible representation under consideration and breaks the equipartition of entanglement. We present two distinct schemes to carry out these computations. The first relies on the evaluation of the charged moments of the reduced density matrix. This involves studying the action of the defect-line, that generates the symmetry, on the boundary states of the theory. This perspective also paves the way for discussing the infeasibility of studying symmetry resolution when an anomalous symmetry is present. The second scheme draws a parallel between the SREE and the partition function of an orbifold CFT. This approach allows for the direct computation of the SREE without the need to use charged moments. From this standpoint, the infeasibility of defining the symmetry-resolved EE for an anomalous symmetry arises from the obstruction to gauging. Finally, we derive the symmetry-resolved entanglement spectra for a CFT invariant under a finite symmetry group. We revisit a similar problem for CFT with compact Lie group, explicitly deriving an improved formula for U(1) resolved entanglement spectra. Using the Tauberian formalism, we can estimate the aforementioned EE spectra rigorously by proving an optimal lower and upper bound on the same. In the abelian case, we perform numerical checks on the bound and find perfect agreement.