Browse Articles

Small matrix path integral study of excitation energy transfer with distance-dependent electronic coupling

We use the small matrix path integral (SMatPI) methodology to examine the impact of electronic coupling strength variation on the population dynamics of model molecular aggregates containing up to five monomers in a single-file arrangement. The excited electronic state of each molecular unit interacts with the intramolecular vibrational modes, while the skeletal vibrations of the aggregate modulate the electronic coupling. The interaction between exciton states and intramolecular vibrations is treated using the iterative SMatPI algorithm, while the skeletal vibrations are included either through an augmented system Hamiltonian or through the ensemble-averaged classical path (EACP) approximation. We compare results obtained using an exponential coupling function of monomer separation, which describes short-distance interactions, and an inverse cubic model, relevant to dipolar interactions at larger monomer separations. We find that the variation of electronic coupling gives rise to behaviors that differ in significant ways from those observed when the coupling is held fixed, generally quenching oscillatory components of exciton populations. These findings supplement the insights derived from earlier work with fixed electronic couplings.

Pigmented region transcriptomics identifies molecular pathways potentially associated with microbial transport in the female squid accessory Nidamental Gland

Abstract In certain cephalopods, the female-specific accessory nidamental gland (ANG) harbors dense microbial communities that are transported to the nidamental gland, incorporated into glandular secretions, and delivered to egg capsules to protect embryos. In mature females, the ANG shows pigmented regions with distinct microbiomes, though host responses remain unclear. Transcriptomic analyses of these pigmented regions in the ANG of mature female bigfin reef squid ( Sepioteuthis lessoniana ) revealed reduced protein synthesis and enhanced fluid/ionic homeostasis, along with enrichment of muscle contraction-related processes, suggesting potential mechanisms associated with microbial transport. Weighted gene co-expression network analysis (WGCNA) identified blue and royalblue modules linked to individual variation and pigment color; the blue module was enriched in cell cycle and protein synthesis-associated processes, while the royalblue module was involved in energy metabolism, fluid/ionic homeostasis, and host-microbiome interaction-associated processes. These results suggest that pigment-associated ANG microenvironments regulate local metabolism, with the host maintaining homeostasis and potentially supporting processes associated with microbial transfer toward the nidamental gland.

Beyond Wigner sampling: Effect of initial conditions and substitution on simulated ESIPT in salicylidene aniline

Upon excitation, salicylidene aniline (SA)-based photoswitches can undergo a sub 100 fs excited-state intramolecular proton transfer (ESIPT), a necessary first step in the overall photoswitching mechanism. Using non-adiabatic ab initio molecular dynamics simulations (NAMD), we have studied ESIPT in SA and selected derivatives with either sterically hindered backbones or electronically active substituents. By comparing different methods used to sample the initial ground-state distribution of the molecule which vary in their capacity to describe low-frequency anharmonic modes and/or quantum effects, we have shown that the ESIPT yield of this molecule is sensitive to the initial conditions, varying by as much as 24%. The ESIPT yield has also been shown to be sensitive to the inclusion of solvents. Finally, we have investigated how molecular substitutions can be used to modulate the ESIPT yield, showing how rational design can be used to increase it by 19%, while also demonstrating the unpredictability of photoinduced reactivity and thus the interest of screening using NAMD.

An improved ResNet50 method for hazardous-region state recognition in CNC press brakes

Rovibrational energy levels of H2O by quantum computing

We calculate rovibrational energy levels of H2O using a trapped-ion quantum computer. We first derive the qubit form of Watson’s Hamiltonian, including the rovibrational coupling terms. In a second step, we employ a variant of the quantum-selected configuration-interaction method to calculate rovibrational energy levels. A truncated form of the qubit Hamiltonian is used to generate correlated rovibrational wave functions on the quantum computer by time evolution, and a basis set is selected by sampling from the measured probability distribution. The rovibrational energy levels are obtained by constructing a Hamiltonian matrix using the selected basis set and diagonalizing the matrix using a classical computer. We show that an accuracy of a few hc cm−1 can be achieved for low-lying rovibrational energy levels.

Prognostic effect of changes in high-density lipoprotein cholesterol after kidney transplantation

How vibrational excitation shakes up the UV/VIS spectrum: A 2D-VE study

Recently, powerful experimental techniques have emerged that use infrared vibrational excitation to modulate UV/VIS spectra for applications such as subensemble-selective photochemistry in VIPER 2D-IR spectroscopy, vibrationally enhanced multiplexing in fluorescence imaging, single molecule vibrational spectroscopy, and IR-induced modulation of photocurrents in optoelectronic devices. Although these approaches rely on IR induced modulation of electronic spectra, they do not directly measure it. Here, we combine ultrafast two-dimensional vibrational–electronic (2D-VE) spectroscopy and theoretical spectroscopy to directly probe how IR pre-excitation impacts the UV/VIS spectrum, using the dye coumarin 6 as an example. We find that IR excitation does not simply shift the electronic absorption band but produces complex spectral changes arising from multiple vibronic transitions. Simulations reproduce the experimental spectra and reveal that dominant contributions originate from changes near the 0–0 transition rather than from a single red-shifted M–0 transition. In addition, oscillatory features in the 2D-VE spectra are observed and assigned to zero-quantum coherences between vibrational modes, demonstrating that vibrational coherences can strongly influence signal amplitudes in VIPER-type experiments. Finally, the correlation between vibrational and electronic frequencies enables the separation and analysis of molecular subensembles, as illustrated for hydrogen-bonded and free coumarin 6 in mixed solvents. These results provide a detailed microscopic picture of how vibrational excitation modifies electronic spectra and offer important insight for understanding and optimizing vibrationally promoted electronic resonance techniques.

Analyzing the spatiotemporal dynamics of land use land cover change and its effects on land surface temperature in Weyib watershed, South Eastern Ethiopia

Organic cation-induced symmetry breaking enables efficient optoelectronic transitions in double halide perovskites

Lead-free double perovskites (A2B+B3+X6) are promising non-toxic alternatives to lead halide perovskites for optoelectronic applications, yet their performance is fundamentally limited by inversion-symmetry-induced parity-forbidden transitions, highlighting the need for systematic exploration of the underlying structure–property relationships and effective symmetry-breaking strategies. Here, based on first-principles calculations, we employ representative Cs2AgInCl6 to systematically investigate how compositional engineering modulates the local distortion of [AgCl6]5− octahedra, transition dipole moments (TDMs), and optical absorption. Theoretical investigations reveal that local distortions effectively lift the parity-forbidden transitions and enhance band-edge absorption. Na or Ga alloying induces only weak distortions and correspondingly almost no enhancement of TDMs, whereas halide substitution exhibits pronounced configuration dependence, with cis arrangements producing substantially larger local distortions and stronger optical activation than trans ones. In contrast, incorporation of organic cations generates pronounced local octahedral distortions through their steric effect and anisotropic hydrogen-bonding interactions, leading to significantly enhanced parity-forbidden transitions and band-edge absorption comparable with MAPbI3. Furthermore, a persistent hydrogen-bond network reinforces the metal–halide framework and improves thermostability. These results establish a robust structure–property relationship between local octahedral distortion and optical activation, highlighting organic cation-induced symmetry breaking as an effective strategy to activate parity-allowed transitions and realize high-performance, stable lead-free DPs for next-generation optoelectronics.

Genetic gains in yield and quality traits of Iranian sugar beet cultivars over four decades

Abstract Sugar beet breeding has been a vital area of research in Iran for over eight decades, with the aim of improving the yield, and quality of this important crop. In this study, an analysis of the progress made in sugar beet breeding over the past 40 years has been presented. This study utilized 15 cultivars of sugar beet. Phenotypic evaluations of these experimental cultivars were carried out across two successive crop years (2022 and 2023). The experimental design adhered to a randomized complete blocks setup with four replications. In the assessment of sugar beet cultivars introduced between 1983 and 2023, the newer cultivars exhibited notably higher white sugar weight (WSW), marking a significant upward trend over the years. Analysis of root weight (RW) and white sugar content (WSC) trends indicated substantial enhancements in these key components impacting WSW. Peak values were evident in the most recent cultivars, contrasting with lower values recorded in earlier decades. Exploring the components of WSC further, sugar content (SC) showed a significant upward trajectory, while molasses sugar percentage (MS) showcased a distinct decrease. Noteworthy declines in sodium (Na⁺) were observed, in contrast to a non-significant rise in potassium (K + ) and a highly significant increase in alpha-amino nitrogen (N). Pearson’s correlation analysis identified positive correlations between WSW and factors like SC, RW, and N. A negative correlation was observed between WSW and Na + , emphasizing the importance of minimizing Na + levels for optimal sugar production. A regression analysis identified SC and RW as the key contributors to WSW variations. Path analysis confirmed the positive direct effects of RW and SC on WSW. Additionally, an indirect positive effect of SC on WSW through RW was identified. Overall, this study highlights significant breeding progress in sugar beets, with substantial improvements in WSW, RW, and WSC. Therefore, breeding programs should focus on enhancing both RW and SC to achieve optimal sugar yield.

Microscopic structure and dynamics of interfacial water at fluorinated vs nonfluorinated surfaces—Insights from <i>ab-initio</i> simulations and IR spectroscopy

Per- and polyfluoroalkyl substances are a class of synthetic chemical compounds widely used as coatings to lower surface energies. However, the microscopic mechanisms of their weak interaction with water and organic compounds remain poorly understood. Here, we perform large-scale density-functional-theory molecular dynamics simulations to investigate water at self-assembled monolayers (SAMs) of fluorinated and non-fluorinated hydrocarbons. We analyze the interfacial water structure and compare it to the prototypical hydrophobic air–water interface. The interfacial water structure at both SAMs closely resembles that at the air–water interface, featuring a distinct depletion layer and a two-dimensional hydrogen-bond network parallel to the surface. Computed anisotropic infrared spectra reproduce key experimental signatures observed in surface-enhanced infrared absorption spectroscopy, including the presence of free OH vibrations directly probing the local surface–water interactions. Notably, while the free OH stretch at the hydrocarbon SAM–water interface exhibits a red shift relative to the air–water interface, indicative of weak binding, the fluorinated SAM–water interface displays a weakly blue-shifted free OH mode. This frequency behavior defies common interpretations based on the vibrational Stark effect. Furthermore, we show that the reorientation dynamics of water molecules are significantly slower near the fluorinated surface, an effect rather expected at hydrophilic surfaces, which we link with spectral line shapes. Our results indicate that fluorinated SAMs, despite being macroscopically more hydrophobic than their unfluorinated counterparts, exhibit characteristics whose spectroscopic interpretation does not align with only hydrophobic or hydrophilic behavior.

A low Q-factor compact wideband microstrip patch antenna with stabilized gain for 5G and IoT applications

First order approximation of polyatomic ion and neutral diffusion in neutral gases under arbitrary fields

This work presents a trajectory-based method for predicting diffusion coefficients of ions and neutral molecules in dilute gases from the thermal limit to strongly driven conditions. Classical trajectory simulations are coupled with two-temperature kinetic theory to evaluate the collision integrals required by the generalized Einstein relations. Polyatomic ion geometries and charge distributions obtained from density functional theory are incorporated directly into 4–6–12 interaction potentials, allowing a consistent treatment of molecular structure, long-range interactions, and energy transfer during collisions. The method is implemented in the Mass Diffusivity Software (MaDiS) and validated against experimental data for both neutral and ionic systems across a wide range of conditions. For neutral molecules in the zero-field limit, the calculated diffusion coefficients reproduce experimental trends across multiple gases and temperatures with an average deviation of ∼5%, despite the use of non-optimized Lennard-Jones parameters. The simulations correctly capture the temperature dependence of diffusivity and remain consistent across a wide range of molecular sizes. Under applied electric fields, the method captures the departure from equilibrium and the resulting anisotropic transport, providing direct predictions of longitudinal and transverse diffusion coefficients. For monoatomic ions, longitudinal diffusion coefficients are reproduced with good agreement over substantial ranges of reduced electric field, typically up to 300–400 Td depending on the ion–gas system, consistent with benchmark datasets. Comparable behavior is obtained for polyatomic ions, demonstrating that the combination of trajectory-derived collision dynamics and the two-temperature formalism remains applicable when realistic molecular structure is included.

Parental warmth, rejection, and overprotection in relation to short-video addiction among adolescents via self-management and social anxiety

Excitation-regulated fluorescence and triplet yield in 3-nitrobenzanthrone: Experimental and theoretical insights into excited-state dynamics

The development of heavy-atom-free triplet materials has emerged as a major research focus due to their potential for diverse photochemical and photophysical applications. Nitroaromatic compounds represent an important class of such systems, exhibiting ultrafast intersystem crossing (ISC), high triplet yields, and rich triplet-mediated photochemistry. Here, we present a comprehensive investigation of the excited-state dynamics of 3-nitrobenzanthrone (NBT), a polycyclic nitroaromatic chromophore of atmospheric and photochemical relevance. Steady-state and time-resolved emission studies reveal that NBT possesses many closely spaced singlet excited states. The fluorescence predominantly originates from the weakly absorbing S1 state, which was confirmed through enhanced fluorescence yield upon direct excitation of the state. In contrast, triplet formation occurs efficiently from the strongly absorbing S2 state. Singlet-oxygen phosphorescence measurements confirm that the triplet yield also depends on the solvent polarity. Femtosecond transient absorption measurements indicated a sequential S2 (LE) → S2 (R*) → Tn pathway with an ISC time constant of ∼10–17 ps depending upon the solvent polarity. Time-dependent density functional theory and spin–orbit coupling calculations support these findings, identifying S2 (1ππ*) → T2 (3nπ*) as the dominant ISC channel. Collectively, the results establish a dual-state photophysical model, in which the solvent polarity and electronic state character govern fluorescence and triplet efficiency in NBT.

Integrated remote sensing and geochemical data of Shadli mineralized metavolcanics (Egypt): mantle plume-driven magmatism during subduction–rift transition

Abstract The Wadi Ranga–Atshan metavolcanic (WRAM) suite in the Southern Eastern Desert of Egypt is part of the Shadli calc-alkaline metavolcanic belt, which is the main crustal part of the Arabian-Nubian Shield (ANS). Integrated remote sensing, mineral compositions, and whole-rock chemical data are used to elucidate the mantle-plume contribution, petrogenesis, and geodynamic evolution of the ~ 739 Ma Shadli metavolcanics. Remote sensing analysis using Landsat-8 and ASTER band ratios in RGB effectively discriminates between the dominant felsic and mafic varieties (bimodal volcanism) and minor intermediate types along with the different alteration zones (e.g., iron- and Al‒OH-rich zones). Its PCA and CEM techniques are used to delineate phyllic, argillic, and propylitic alteration zones and their associated Cu–Fe–Zn sulfides, iron oxides, and malachite mainly along the NW–SE shear zones. The whole rock chemistry indicates that mafic rocks (metabasalts) and felsic to intermediate types (metarhyolites, metadacites, and metabasaltic andesites) show tholeiitic and calc-alkaline natures, respectively. But alkali metabasalts exhibit alkaline affinity. The calc-alkaline metavolcanic protoliths are derived from 10–20% partial melting of a depleted spinel lherzolite mantle source, supported by their low REEs (ΣREEs &lt; 20 ppm) contents. They are further characterized by enrichment in LILEs and depletion in HFSEs (Nb &lt; 2.6, Ta &lt; 0.08, and Ti &lt; 53.31 ppm), suggesting a typical arc-related magmatic signature. In contrast, the alkali metabasalt protoliths are derived from low partial melting (~ 5% melting) of the enriched garnet lherzolite or garnet–spinel lherzolite source in deeper and enriched mantle parts, supported by their high REEs (ΣREEs: 212 ppm) contents. The alkali metabasalts are strongly enriched in HFSEs (Ti &gt; 14,676, Nb &gt; 28.9, and Ta &gt; 1.7 ppm) along with high Cr (up to 337.8 ppm) and Ni (up to 245.1 ppm) relative to calc-alkaline types, consistent with intraplate (OIB-like type) magmatism due to upwelling of mantle plume. The investigated metavolcanics plot in MORB–arc and within-plate/OIB fields, reflecting coexistence of OIB-like (mantle plume-derived melts) and arc/MORB-like basaltic melts, together with arc-like magma signatures; these results indicate tectonomagmatic evolution of the studied rocks from supra-subduction arc magmatism to intraplate rifting transition during the arc assembly of the ANS. Therefore, the different partial melting, magmatic affinity, and magma source (mixed plume–arc magmas) possibly reflect plume-driven magmatism during the subduction–rift transition of the ANS. This transitional environment may be characterized by a sequence of magmatic sulfide mineralization (disseminated pyrite and chalcopyrite) to post-magmatic hydrothermal alteration and supergene oxidation assemblages (gossans, talc–carbonate, malachite, and chrysocolla). These processes were structurally controlled by NW–SE (Najd-related) and NE–SW shear zones that developed during the subduction–rift transition, which facilitated mantle-derived magmatism and fluid migration, thereby generating volcanogenic massive sulfide (VMS) mineralization. The arc-related hydrothermal systems, plume-related ore systems, and later metasomatic overprints may highlight the metallogenic significance of the ANS.

Efficient method for calculation of low-temperature phase boundaries

Understanding phase stability and phase transformations is central to predicting material behavior under varying thermodynamic conditions. One of the earliest and most influential applications of density functional theory in materials science has been the prediction of pressure-induced phase transitions at 0 K. Extending these calculations to finite temperatures, however, requires accounting for thermal, quantum, and anharmonic contributions to the free energy, often at significant computational cost. In this work, we present a general and efficient framework for calculating low-temperature phase boundaries by combining the Clausius–Clapeyron equation with the quasi-harmonic approximation. This methodology requires a minimal number of calculations, while naturally incorporating internal degrees of freedom as well as quantum and low-order anharmonic effects. We illustrate the accuracy and efficiency of the approach by constructing the phase diagram of silica in the pressure range from −2 to 12 GPa and temperatures up to 1750 K. To this end, we employ a machine-learned interatomic potential trained on density functional theory reference data, enabling well-converged free energy estimates via efficient thermodynamic sampling and a rigorous comparison between the proposed framework and free energy integration.

Composition-engineered Sr1−xBaxTiO3 for high-efficiency dielectric resonator antennas in 5G/6G bands

Abstract We report Sr 1−x Ba x TiO 3 (x = 0.0–0.4) nanoparticles synthesized by a tartrate-precursor combustion route and evaluate them for sub-6 GHz dielectric resonator antennas (DRAs). Structural (XRD, FTIR), microstructural (SEM/TEM), ferroelectric (P–E), thermal-conductivity, and broadband microwave-dielectric (1–15 GHz) characterizations identify x = 0.1 as the composition with the best balance of moderate effective permittivity, low loss, and stable GHz dispersion. A cylindrical DRA is then designed with Sr 0.9 Ba 0.1 TiO 3 as the matching layer between a Rogers 6010 resonator and a Rogers 4003 feed/ground laminate, and benchmarked against identical-geometry FR-4 and Rogers TMM4 matching layers. Simulated and measured S-parameters confirm efficient impedance matching (|S 11 | min  ≈ − 25 dB; VSWR &lt; 2), high realized gain, and stable radiation across 2.25–3.25 GHz, demonstrating that composition-engineered SBTO is a practical option for 5G/early-6G front-ends.

Velocity imaging study of charge exchange reactions between He+ and N2

Molecular nitrogen (N2) is a major constituent of the earth’s atmosphere. Its charge exchange collisions with helium ion (He+) from the solar wind lead to N2+, N, and N+ yields, and these ionic yields, together with their neutral co-products, will participate into subsequent atmospheric reactions. Here, we investigate charge exchange (CE) only and dissociative charge exchange (DCE) reactions, He+(2S) + N2 (X1Σg+) → N2+ + He/N+ + N + He, by detecting the N2+ and N+ yields with a crossed-beam ion velocity map image technique. In the collision energy range of 1.25–3.96 eV, the angular and kinetic energy distributions of the CE-yield N2+ indicate collision-energy dependences while a persistent dominance of the resonant process; three channels of the DCE reaction are successively accessed with the enhancement of collision energy, producing N(4S) + N+(3P), N(4S) + N+(1D), and N(2D) + N+(3P). The N+ velocity images are further analyzed with the Doppler kinematics model, indicating two different pathways of each channel, namely, prompt and slow processes. Branching ratios of these channels and pathways are estimated, indicating the predominance of the channel leading to the ground-state yields N(4S) + N+(3P).

Structure-aware long-form audio classification and multi-class dataset construction for the intangible cultural heritage dong folk polyphonic singing