Browse Articles

Effect of tele-support on attention levels of emergency medical technicians during simulated out-of-hospital cardiac arrest

Secure facial biometric authentication in smart cities using multimodal methodology

Loss of the liver circadian clock affects the expression of intrarenal renin-angiotensin system components

Abstract The intrarenal renin-angiotensin system (irRAS) regulates Na + and fluid retention to counteract low blood pressure. Some of its components are expressed with daily rhythms. The circadian metabolism and physiology of the liver can synchronize gene expression in other organs. Hence, we tested whether the liver circadian oscillator could coordinate daily fluctuating expression of irRAS components. To this end, we used two different knock-out mouse strains lacking circadian oscillators specifically in hepatocytes to investigate the impact of this inactivation on their irRAS. Surprisingly, daily fluctuations in expression of many irRAS components in these animals were still detectable but with different phases. The data indicate that signals from liver can synchronize most of the irRAS components tested independent of its circadian oscillator. Both hepatocyte-specific knock-out mouse strains had reduced expression of the Na + /H + exchanger 3 ( Nhe3 ) in kidney, which may explain the ~ 25% reduction in their systolic and diastolic blood pressure. Taken together, our study suggests that mice can use an alternative way of communication between liver and kidney to regulate the daily fluctuations of irRAS components. Identification of this mode of communication could help to better understand the pathophysiology of the kidney, which affects fluid balance and blood pressure.

An optimized YOLOv8n based model for real time defect detection in taro strip production

The non-synthetic sweeteners, miraculin and mogroside V, but not stevia, disrupt the intestinal epithelial barrier function through a sweet taste receptor-dependent mechanism

Abstract Impaired intestinal barrier function is a precursor to various metabolic diseases which can occur when the intestinal epithelium is directly exposed to certain dietary components. Previous studies have demonstrated the barrier disruptive effect of artificial sweeteners such as sucralose and saccharin, in the intestinal epithelium. In the present study, we aimed to evaluate the impact of 3 non-synthetic sweeteners, stevia, miraculin, and mogroside V, on Caco-2 monolayer barrier integrity, reactive oxygen species (ROS) production, and tight junction protein expression as compared to the artificial sweetener saccharin. Miraculin and mogroside V exerted a significant impact on cell numbers with decreased cell viability at both 24 and 48 h. ROS production was also significantly increased by miraculin and mogroside V and epithelial barrier function, assessed by transepithelial electrical resistance and FITC-dextran leak, was significantly disrupted with both miraculin and mogroside V. Stevia exhibited no effect on epithelial cell viability, ROS accumulation or barrier function, despite a range of concentrations investigated. Knockdown of the sweet taste receptor, T1R3, significantly attenuated miraculin- and mogroside V-induced loss of cell viability, ROS accumulation and barrier disruption suggesting a T1R3-dependent mechanism. Gene expression analysis revealed differential regulation of cell junction-related genes by mogroside V and miraculin with upregulated expression of genes such as CAV1 , CLDN2 and CLDN10 , and downregulated expression of genes such as CAV3 and CDH2 . These findings demonstrate that miraculin and mogroside V, but not stevia, negatively regulate ROS formation and intestinal epithelial barrier function in a T1R3-dependent manner and potentially through modulation of tight junction proteins. This highlights the need for further investigation into the long-term dietary implications of natural sweeteners, particularly miraculin and mogroside V, on gut health.

Numerical study of the effect of the relative mobilities of chemical components on the non-solvent induced phase separation process for membrane elaboration

The filtration membranes are often elaborated through a phase separation process where a polymer rich phase and a polymer poor phase spontaneously form through spinodal decomposition. One process that is still not well understood from a theoretical point of view is the non-solvent induced phase separation, where a thermodynamically stable film of a polymer mixture is put in contact with a bad solvent of the polymer. The invasion of the film by this non-solvent drives the film out of stability and leads to spinodal decomposition. During this phase separation, polymer poor and polymer rich regions form. In this article, we present a numerical study of the effect of kinetic coefficients, namely, the relative mobilities of polymer and solvent/non-solvent, on the observed patterns. Using 2D numerical simulations of the ternary Cahn–Hilliard model, we show that, for a given thermodynamic landscape, this parameter has dramatic effects: depending on its value, phase separation may or may not occur. We also show that it can affect the nature of the resulting pattern. In addition to analyzing 3D simulations, we characterize the final pattern using a quantitative indicator of connectivity and show that, for a wide range of initial compositions of the film, the final pattern is bicontinuous. Finally, we also quantify the transport properties of both polymer rich and polymer poor domains.

High-resolution photofragmentation spectroscopy and global vibronic modeling of N2O+ <i>X</i> 2Π and <i>A</i> 2Σ+ states

The spectral signature of N2O+ has been measured in the 30 500–32 500 cm−1 region at high spectral resolution by photodissociation spectroscopy using the STARGATE setup. Seventeen vibronic bands were observed and assigned for the first time. Those were incorporated into a global fit that also includes all low resolution available literature data for the two lowest electronic states, i.e., X2Π and A2Σ+. Renner–Teller and spin–orbit interactions are considered in this global modeling. In addition, a line-by-line rovibronic analysis of the most intense bands enabled the determination of molecular constants of the (v1v2v3) = (101) vibrational state of the A2Σ+ electronic state. This work represents the first global vibronic fit of N2O+ simultaneously treating the X2Π and A2Σ+ states.

Dual effect of cholesterol on interfacial water dynamics in lipid membranes: Interplay between membrane packing and hydration

Water contained within biological membranes plays a critical role in maintaining the separation between intracellular and extracellular environments and facilitating biochemical processes. Variations in membrane composition and temperature lead to phase state changes in lipid membranes, which in turn influence the structure and dynamics of the associated interfacial water. In this study, molecular dynamics simulations were performed on membranes composed of dipalmitoylphosphatidylcholine (DPPC) or palmitoyl sphingomyelin mixed with cholesterol (Chol). To elucidate the effects of Chol on interfacial water, we examined the orientation and hydrogen-bonding behavior of water molecules spanning from the membrane interior to the interface. As the Chol concentration increased, a transient slowdown in water dynamics was observed in the ripple phase at 303 K. Conversely, at higher Chol concentrations, water dynamics were accelerated relative to pure lipid membranes across all temperatures studied. In particular, at a Chol concentration of 50%, the hydrogen bond lifetime in DPPC membranes decreased to ∼0.5–0.7 times that of pure lipid membranes. This nonmonotonic behavior is attributed to the combined effects of membrane packing induced by Chol and reduced density of lipid molecules in the hydrophilic region, offering key insights for modulating the dynamical properties of interfacial water.

Efficient spectra from atomistic simulation: A generalized master equation study of the air–water interface

Computing condensed phase spectra from atomistic simulations requires calculating correlation functions from molecular dynamics and can be very expensive. A totally general, data-driven method to reduce cost is to employ an exact rewriting to a generalized master equation characterized by a memory kernel. The decay time of the kernel can be less than the original function, reducing the amount of data required, but it can also be more. In this paper, we construct the minimal projection operator to predict vibrational sum-frequency generation spectra and apply it to the air–water interface simulated using ab initio molecular dynamics. We find the kernel is shorter lived than the correlation functions, yielding equivalent spectra when truncated to around 50% of the duration. We explore various avenues to use more of the available data to expand the projector in an attempt to reduce the cost further. Interestingly, we are not able to effect any change by including quadrupoles, intermolecular couplings, or depth-dependence. How to strategically go about maximally reducing cost using projection operators remains an open question.

Low-rank matrix and tensor approximations for compression of machine-learning interatomic potentials

Machine-learning interatomic potentials (MLIPs) have become a mainstay in computationally guided materials science, surpassing traditional force fields due to their flexible functional form and superior accuracy in reproducing physical properties of materials. This flexibility is achieved through mathematically rigorous basis sets that describe interatomic interactions within a local atomic environment. The number of parameters in these basis sets influences both the size of the training dataset required and the computational speed of the MLIP. Consequently, compressing MLIPs by reducing the number of parameters is a promising route to more efficient simulations. In this work, we use low-rank matrix and tensor factorizations under fixed-rank constraints to achieve this compression. In addition, we demonstrate that an algorithm with automatic rank augmentation helps to find a deeper local minimum of the fitted potential. The methodology is mainly verified using the Moment Tensor Potential (MTP) model and benchmarked on multi-component systems: a Mo–Nb–Ta–W medium-entropy alloy, molten LiF–NaF–KF, and a glycine molecular crystal. The proposed approach achieves up to 50% compression without any loss of MTP accuracy. We also demonstrate that the developed methodology is universal and can be applied to compress other MLIPs on the example of atomic cluster expansion.

Relativistic core–valence-separated equation-of-motion coupled-cluster singles and doubles method: Efficient implementation and benchmark calculations

An efficient implementation for the relativistic exact two-component core–valence-separated equation-of-motion coupled-cluster singles and doubles (X2C-CVS-EOM-CCSD) method is reported. The explicit exclusion of pure valence excitations in the EOM-CCSD excited-state eigenvalue equations significantly improves the efficiency for calculations of core-excited states. Benchmark relativistic CVS-EOM-CC calculations with systematic inclusion of relativistic, correlation, and basis-set effects are shown to provide highly accurate results for core ionized and excited states involving heavy atoms.

Cavity-modified nonequilibrium Fermi’s golden rule rate coefficients from cavity-free inputs

The Nonequilibrium Fermi’s Golden Rule (NE-FGR) provides a convenient theoretical framework for calculating the charge transfer (CT) rate between a photoexcited bright donor electronic state and a dark acceptor electronic state when the nuclear degrees of freedom start out in a nonequilibrium initial state. In this paper, we show that NE-FGR rates can be significantly modified by placing the molecular system inside an electromagnetic microcavity, even when the coupling with the cavity modes is weak. In this case, cavity-modified NE-FGR rates can also be estimated from the same inputs needed for calculating the cavity-free NE-FGR rates, thereby bypassing the need for an explicit simulation of the molecular system inside the cavity. We also introduce an approximate limit of the cavity-modified NE-FGR, which we denote cavity-modified instantaneous Marcus theory, since it is based on the same assumptions underlying Marcus theory. The utility of the proposed framework for calculating cavity-modified NE-FGR rates is demonstrated by applications to photo-induced CT in the carotenoid–porphyrin–C60 molecular triad dissolved in liquid tetrahydrofuran and the Garg–Onuchic–Ambegaokar model for a CT reaction in the condensed phase.

Analyzing the response of exchange–correlation potentials of chain-like molecules to electric fields by Kohn–Sham inversion and evaluation of the response within the random phase approximation

Kohn–Sham inversion based on CCSD(T) (coupled cluster singles doubles with perturbative triples) electron densities is employed to calculate the response of the exchange–correlation (XC) potential to an external electric field for hydrogen chains of varying length with alternating H–H distances of 2 and 3 bohrs in order to provide reference data and to analyze the response of the XC potential. The exchange part of the exact XC potential exhibits an ultranonlocal field-counteracting behavior, known from calculations using the exact-exchange-only (EXX) optimized effective potential (OEP) method. The correlation part also counteracts an applied field but is significantly smaller. The magnitude of the correlation contribution grows with chain length, indicating its increasing importance in the description of the electric response for spatially extended systems. Interestingly, the correlation potential from the random phase approximation (RPA) OEP method, i.e., from a self-consistent RPA method, which closely approximates the exact correlation potential in the absence of an electric field, instead amplifies the applied field. Despite this, the RPA-OEP method substantially outperforms EXX-OEP in predicting optical properties, such as polarizability. This improvement is due to the accurate XC potentials and electron densities it yields in the absence of an electric field, as well as its reasonably good response to an external field within the interior of the hydrogen chains, which benefits from error cancelations between exchange and correlation. In addition, we analyze the quadratic response of the XC potential to the external field, which exhibits a non-trivial collective behavior, with a magnitude increasing with chain length.

Quantum simulation of electron energy loss spectroscopy for battery materials

The dynamic structure factor (DSF) is a central quantity for interpreting a vast array of inelastic scattering experiments in chemistry and materials science, but its accurate simulation poses a considerable challenge for classical computational methods. In this work, we present a quantum algorithm and an end-to-end simulation framework to compute the DSF, providing a general approach for simulating momentum-resolved spectroscopies. We apply this approach to the simulation of electron energy loss spectroscopy (EELS) in the core-level electronic excitation regime, a spectroscopic technique offering sub-nanometer spatial resolution and capable of resolving element-specific information, crucial for analyzing battery materials. We derive a quantum algorithm for computing the DSF for EELS by evaluating the off-diagonal terms of the time-domain Green’s function, enabling the simulation of momentum-resolved spectroscopies. To showcase the algorithm, we study the oxygen K-edge EELS spectrum of lithium manganese oxide (Li2MnO3), a prototypical cathode material for investigating the mechanisms of oxygen redox in battery materials. For a representative model of an oxygen-centered cluster of Li2MnO3 with an active space of 18 active orbitals, the algorithm requires a circuit depth of 3.25 × 108 T gates, 100 logical qubits, and roughly 104 shots.

Erratum: “Developments and further applications of ephemeral data derived potentials” [J. Chem. Phys. 159, 144801 (2023)]

Perspectives on surface sum-frequency spectroscopy

This paper explores possible improvements to surface-specific sum-frequency spectroscopy toward a more versatile and powerful surface probe. Several suggestions are made to broaden the applicability of the technique, including the introduction of dual-comb sum-frequency spectroscopy, which is expected to greatly enhance the signal strength. The paper also highlights existing confusion and misinterpretation in spectral analysis used to interrogate interfaces. To address this issue, a framework is suggested that defines material response coefficients extractable from measured spectra in terms of averages of microscopic quantities that characterize an interface. Such response coefficients can be theoretically calculated for comparison with the extracted ones. Comments on works in three areas that have garnered considerable attention in recent years are given. It is seen that these results are either incorrectly presented, misinterpreted, or overstated.

Development of SAFT-based heteronuclear fused coarse-grained models of short alkanes and their mixtures with carbon dioxide and nitrogen

Coarse-grained models for short n-alkanes were developed that capture the vapor–liquid equilibria of both their pure components and their mixtures with carbon dioxide (CO2) and nitrogen (N2) over a wide range of temperatures and pressures. We utilized an equation of state, namely Statistical Associating Fluid Theory (SAFT), in which chain models were composed of fused segments interacting via the Mie potential, parameterized according to group contribution principles. The molecular parameters predicted by SAFT were used as initial guesses to determine the necessary adjustments to make these models suitable for molecular simulations, helping to reduce the complexity of the optimization problem, and adjustments were made by expanding our methodology [Chremos et al., J. Phys. Chem. B 129, 3443 (2025)] developed on homonuclear diatomic molecules to heteronuclear chain models. We performed Wang–Landau transition-matrix Monte Carlo simulations in the grand canonical ensemble, ranging from methane up to n-hexane, and evaluated the phase behavior. The mixtures of short n-alkanes with CO2 and N2 were also investigated with the Gibbs ensemble at constant pressure. In addition, we also developed SAFT-γ Mie parameters for N2 mixtures with n-alkanes. The performance of our coarse-grained models was further evaluated in ternary mixtures. Overall, we found excellent agreement over a wide range of temperatures and pressures in pure components and mixtures. Our findings establish the foundations for a group contribution framework for thermodynamically consistent coarse-grained models.

Kinetic photocycle description of photochemically induced dynamic nuclear polarization for dye-sensitized solid-state NMR spectroscopy

Solid-state photochemically induced dynamic nuclear polarization (photo-CIDNP) enables the amplification of the nuclear magnetic resonance (NMR) signal in linked donor–acceptor (D–A) systems under light irradiation. At high fields, the effect relies on the creation of a transient radical pair having a large initial spin order, which is spontaneously transferred to hyperfine-coupled nuclear spins and converted into polarization during the evolution of the system within the zero-quantum electron spin manifold. Previous quantum mechanical models to quantify the solid-state photo-CIDNP effect were based on a simplified representation of the D–A photocycle and did not account for the possibility of re-exciting the molecule after the radical pair state decays back to the molecular ground state. Here, we present a model for the quantification of solid-state photo-CIDNP using a unified master equation that spans all relevant photocycle states in Liouville space to account for their simultaneous evolution. The model accounts for multiple photocycle states interconnected by kinetic rates, with the various photocycle transitions described as spin-conserving Markovian processes. We first apply the simplified model to identify conditions for solid-state 1H photo-CIDNP at high magnetic fields (here, 9.4 T), and then, based on the information gathered in this way, we explore different cases with the unified model to identify potential design factors for second-generation D–A polarizing agents for dye-sensitized solid-state NMR experiments.

Understanding of molecular motions in nonadiabatic photoisomerization dynamics of cis-stilbene with on-the-fly simulation of transient absorption pump–probe spectra

Theoretical simulations of time-resolved transient absorption spectra, combining on-the-fly trajectory surface hopping with doorway–window formalism, provide a powerful approach to unravel the nonadiabatic dynamics of cis-stilbene. The results show that the key molecular motions driving photoisomerization are captured by the evolution of spectral components, including ground-state bleach, stimulated emission, and excited-state absorption. By establishing a critical link between nuclear dynamics and time-resolved spectral responses, this work demonstrates the essential role of theoretical spectroscopy in decoding ultrafast photochemical processes and offers a predictive framework for mapping molecular dynamics from spectral signatures.

Temperature induced metallicity of the Si(001) surface: Insights from molecular dynamics simulations with machine learned interatomic potentials

The temperature-dependent structural dynamics of Si dimers on the reconstructed Si(001) surface are investigated using molecular dynamics simulations with a newly developed machine learned interatomic potential trained on a database derived from density functional theory-based calculations. We find a finite probability of dimers occupying the higher energy symmetric configurations (associated with metallic behavior) even at temperatures as low as 300 K and that this probability continues to grow with increasing temperature as the lower energy asymmetric dimers flip rapidly with rates ranging from 106 to 109 s−1. Furthermore, above 700 K, some dimers are found to dissociate, leading to the presence of Si adatoms on the surface. These results are in accord with the experimental observations of metallicity on Si(001) with an onset around 400 K, which increases with increasing temperature followed by an abrupt rise around 700 K. By capturing the dynamics of dimer flipping, which on average reflect a domination of the symmetric configuration over the ground state asymmetric geometry, these simulations provide a rationale for the origin of the observed metallicity.