Browse Articles

Effect of wheat straw protein hydrogel on the mechanical and compressibility behavior of dispersive soil

Insufficient physical activity and diabetes mellitus prevalence in Iran: an estimated population attributable fraction analysis using STEPS 2021 data

Effects of biochar and irrigation regime on soil carbon and nitrogen distribution in wheat fields: a two-year field study

A regret-based three-way decision with novel intuitionistic fuzzy similarity in an intuitionistic fuzzy information system

The application of intelligent generation model for international discourse of grand canal culture based on artificial intelligence and BPNN model

Designing a secure anonymous group-oriented key agreement protocol for the internet of medical things

Diagnostic efficacy of circulating tumor cell in clinically significant prostate cancer

Clinical significance of serum levels of 14-3-3β protein in patients with non-small cell lung cancer

Quality retention and energy optimization in ohmic vacuum concentration of white mulberry syrup

Quantum tunneling on water. I. General framework for microdroplet redox chemistry

Microdroplet chemistry has emerged as a fascinating field. In particular, a plethora of unexpected oxidation and reduction reactions are observed at the air–water interface, with wide implications on chemical science, industry, and beyond. However, the explanation of microdroplet redox chemistry is challenging and controversial. Mechanistically, thermodynamic reversal over the bulk reaction, surprisingly fast kinetics (often less than milliseconds), and generality of a broad scope of substrates defy textbook understanding. Herein, we propose and justify a theoretical model of quantum-tunneling-based, concerted, interfacial electron transfer of OH−partiallysolvated+An→OH·partiallysolvated+An−1, rather than the conventional stepwise ionization-capture picture. We then introduce a solvation-dependent free-energy distribution for the partial solvation of OH− at a heterogeneous water interface and develop a Marcus-theory-based reaction rate formalism that integrates the energetic distribution. Four different electron acceptors An (including a transition metal, an organic molecule, oxygen, and ozone) are chosen to cover a wide range of experimental scenarios and chemical diversity. When An in the system is reduced upon receiving an electron from OH− across the thin interface, the accompanied product of OH· further serves as the oxidizing agent, capturing the intrinsic oxidative capacity of microdroplet. We quantitatively analyze both the thermodynamic and the kinetic consequences of this model. For all four cases analyzed, the otherwise unfavorable thermodynamic penalty (ΔG° > 0) for the bulk reaction is reversed at the water interface (ΔG° < 0) after a certain dehydration level. Remarkably, for all these cases, interfacial electron transfer becomes near-barrierless (ΔG°≈−λ, ΔG‡≤3 kcal/mol) for a substantial sub-population of partially solvated OH−. Thus, the water interface can prepare and gate a considerable donor population whose electrons are nearly ready to quantum mechanically tunnel into a broad range of acceptors across the thin interface, which explains the surprisingly fast reaction rate observed in experiments. This model further predicts absolute rate constants that are comparable with kinetic measurement on microdroplets. Finally, a phase diagram is constructed to depict the vast thermodynamic and kinetic (barrierless reaction) zones that are newly opened for a general An by the water interface, thus accounting for reaction generality. Despite its simplicity, this model provides a robust explanation and prediction for the rich redox chemistry at a water interface.

The effects of ionic valency and size asymmetry on counterion adsorption

We study the effect of asymmetry in solvent and ionic size on the equilibrium properties of multivalent ionic solutions near a charged surface. For a single ionic species in solution, we derive a generalized Grahame equation at the charged surface. For a general size ratio between the ions and the solvent, we obtain analytical results for the concentration profiles as a function of the distance from the surface. For a weak surface charge and small ion-to-solvent size ratio, the profile follows the classical Poisson–Boltzmann equation in dilute solution conditions. However, for high surface charge and large ionic size, the concentration profile saturates near the surface, leading to distinctive dependencies of the solution properties on the surface charge density and size asymmetry. Furthermore, the crossover between dilute and saturated regimes depends on the surface charge and ionic size asymmetry. We suggest that a solution containing multiple ionic species of different valencies and sizes stratifies close to the surface in the saturation regime. This leads to the formation of layers that are ordered according to the ions’ valency-to-size ratio.

Tunable dissolution of poorly soluble gliclazide by surface coating via room-temperature atomic layer deposition

Gliclazide (GLZ) is a sulfonylurea antidiabetic drug widely used to treat type 2 diabetes mellitus. However, its poor aqueous solubility is a major challenge in drug formulation, often limiting the bioavailability and therapeutic efficacy. In this study, we explore the application of atomic layer deposition (ALD) as a surface engineering technique to enhance the wettability and tailor the dissolution of GLZ. By coating the drug particles with ultra-thin SiO2 films, their wettability is transformed from strongly hydrophobic to highly hydrophilic, promoting a highly dispersed state in an aqueous medium and significantly accelerating the dissolution. More importantly, by controlling the coating thickness, the dissolution rate of GLZ can be tailored, enabling tunable drug dissolution profiles. The results demonstrate the potential of SiO2 ALD not only in overcoming solubility-related limitations but also in providing a method of multipurpose design for controlled drug delivery. Given its compatibility with pharmaceutical manufacturing, our approach presents a promising pathway to enhance bioavailability and optimize the release kinetics of other poorly soluble drugs.

Decoherence-induced adaptive multiconfigurational Ehrenfest dynamics for nonadiabatic scattering simulations

Theoretical simulation of nonadiabatic scattering dynamics involves delicate treatment of both electronic coherence and decoherence all the time. In this study, we investigate the multiconfigurational Ehrenfest (MCE) dynamics with adaptive basis set expansion to capture the growing entanglement between the electronic states and the nuclear degrees of freedom with time, which shares the same features with the well-known overcoherence problem in the traditional Ehrenfest mean field method. Inspired by the decoherence studies in the framework of mixed quantum–classical dynamics, we here propose a decoherence-induced adaptive MCE (DA-MCE) method, which can deal with the coherent propagation and quantum decoherence in nonadiabatic scattering dynamics simultaneously. As demonstrated in the three famous Tully models, DA-MCE can efficiently capture the time evolution of the reduced density matrix, the Stueckelberg interference, and the rapid decoherence. In particular, both the adaptive expansion of the basis set and the form of the variational Ansatz are found to be highly important for the description of complex dynamics. Compared to the multiconfigurational surface hopping method proposed recently, our DA-MCE can also be regarded as a multiconfigurational version of the branching corrected mean field method, which indicates the potential combination of general mixed quantum–classical trajectories with the proposed multiconfigurational approach.

Quantum tunneling on water. II. Quantitative rate formalism of barrierless electron transfer and application to oxidation reactions

In contrast to its presumably inert bulk counterpart, the air–water interface of microdroplets exhibits surprising redox reactivity, enabling both oxidation and reduction of a wide range of substrates. We have recently proposed a theoretical model of interfacial quantum tunneling to rationalize microdroplet redox chemistry. By generalizing Marcus’ theory of concerted electron transfer to heterogeneous interfacial water environments, this model is able to qualitatively explain the counterintuitive thermodynamics and kinetics of redox chemistry observed on the air–water interface. Following the general framework developed in Part I, this study quantitatively analyzes the solvation distribution Pθ of OH− donors from a statistical mechanics perspective and further derives a closed-form rate expression for barrierless electron transfer. The resulting compact formalism highlights a distinct interfacial pathway to reach donor–acceptor energy degeneracy and mathematically shows how interfacial water can facilitate and gate electron tunneling, complementing the classical Marcus picture of solvent reorganization. Fundamentally, translational symmetry is broken at the air–water interface, unlocking a new degree of freedom of solvation coordinates that are otherwise inaccessible in the bulk. For practical estimates, a phenomenological exponential model for Pθ is proposed and evaluated with the input of interfacial water structure. When applied to the spontaneous formation of H2O2 in water microdroplets with molecular O2 and O3 as electron acceptors, this formalism yields reasonable agreement with experimental measurements, which, to the best of our knowledge, marks the first attempt to predict on-water redox reaction kinetics from first principles. Hence, both the physical underpinning and practical utility of our model are firmly supported. The newly developed rate formalism is expected to facilitate quantitative modeling and calculation of redox chemistry on water.

Mechanisms for light emission enhancement from low lying doublet states in copper porphyrin <i>H</i> -aggregates

Open-shell molecules are emerging as promising candidates for quantum information science, yet a fundamental understanding of how aggregation influences their optical properties remains limited, largely due to the lack of well-defined model systems. Here, we investigate H-aggregate formation in two copper porphyrin monomers with different peripheral meso substituents and examine how aggregation modulates light emission processes through exciton delocalization. We identify spectral signatures consistent with delocalized B-state excitons arising from H-aggregate formation, which lead to enhanced light emission from monomeric Cu-porphyrins relative to dimeric counterparts. A model incorporating non-Condon vibronic coupling was developed to propose that Q-state emission becomes enhanced by a factor that depends quadratically on the number of molecules over which the B-state exciton delocalizes. In addition, enhanced emission from the 2T state is assigned to a thermally activated delayed fluorescence mechanism that depends on triplet exciton delocalization that is mediated by exchange interactions between the unpaired Cu2+ d electron and the eg porphyrin orbitals. We develop a kinetic model based on simple Hamiltonians that yields a good agreement between simulated and experimentally measured 2T emission decay dynamics. Together, these results demonstrate how controlled aggregation can be used to tune exciton delocalization and excited-state dynamics in open-shell metalloporphyrin systems that may play a role in their application to quantum information.

Quantifying chirality in helical polymers via a geometric extension of the Kremer–Grest model

Chirality in polymeric systems enables a wide range of emergent optical, mechanical, and transport phenomena, yet a unified framework that quantitatively connects molecular-scale geometry to chiral behavior remains lacking. Existing theoretical descriptions typically emphasize either continuum models, such as the helical wormlike chain (HWLC), which neglect intermolecular interactions, or mesophase-level theories, which obscure the role of molecular geometry. In this work, we introduce a comprehensive framework for quantifying chirality in helical polymers by extending the Kremer–Grest bead–spring model to explicitly map intrinsic curvature and torsion onto bond angle and dihedral potentials. We establish direct theoretical relationships between helical parameters such as pitch and radius and connect them to a normalized, dimensionless chirality characteristic, χ, that captures local geometric correlations absent from conventional HWLC descriptions. Furthermore, using molecular dynamics simulations, we systematically quantify the influence of excluded volume interactions and thermal fluctuations on helical geometry and chirality, dispelling the common assumption that monotonic increases in chirality are associated only with decreasing pitch. Finally, we present a coarse-graining procedure that facilitates a direct comparison between experimental helical polymers and the Kremer–Grest helical chain, demonstrating quantitative agreement across a diverse set of polymer classes. This unified geometric and particle-based description provides a predictive roadmap for selecting and engineering chiral Kremer–Grest models and offers a general platform for designing polymeric materials with controlled and tunable chirality.

Semi-universal solution of the Thomas–Fermi equation for neutral jellium spheres

The Thomas–Fermi model of electronic structures provides a universal solution for neutral atoms. As a result, the energy of a neutral atom with nuclear charge Z is given as −0.7687Z7/3. Are there other systems where such universal solutions can be found? In this work, we look for an answer to this question and discover that for neutral jellium spheres, a semi-universal solution of the Thomas–Fermi equation exists; one parameter, f = N2/3rs, determines the properties of many neutral jellium spheres with different numbers of electrons (N) and bulk density parameters (rs). This parameter is connected to an earlier approximate analytical solution given in the context of simple metal clusters. The Thomas–Fermi energy of a neutral jellium sphere is found to be a simple function of f and N, of a form similar to that for atoms. Additional examples of semi-universal solutions are given by generalizing our method to other potentials. The present work, therefore, provides a motivation to explore whether such universal forms can be found in more accurate orbital-free density functional theories.

Relativistic strengthening of hydrogen bonds in bihalide anions: A four-component CCSD(T) study

In this study, we systematically investigate relativistic effects in bihalide anions [XHX]− (X = F, Cl, Br, I) using four-component coupled-cluster calculations based on the Dirac–Coulomb Hamiltonian at the CCSD(T) level. Relativistic contributions are quantified by comparing results obtained with the four-component Dirac–Coulomb and Lévy–Leblond Hamiltonians, both combined with a Gaussian nuclear charge distribution model. Relativistic effects are intrinsic to molecular systems and can, in principle, modify hydrogen-bond strengths alongside solvation, nuclear quantum effects, and nuclear dynamics. We identify two distinct regimes of relativistic behavior for bihalide anions with light (F, Cl) and heavy (Br, I) halogen nuclei. Relativistic effects lead to a measurable enhancement of hydrogen bonding as reflected in rovibrational constants (vibrational frequencies and rotational constants), equilibrium geometries, thermodynamic parameters, and the electron-density distribution, in contrast to the known trend of relativistic weakening of covalent bonding in the neutral hydrogen halides HX (X = F, Cl, Br, I). The maximum relativistic strengthening of the hydrogen bond is about 0.6–0.7 kcal/mol, while the relativistic localization of electron density in the internuclear region amounts to ∼0.1%–3.0%.

Statistical physics of the two-dimensional Coulomb liquid with ionic hard-core size

A self-consistent theory of bulk electrolytes incorporating electrostatic and hard-core interactions on an equal level is applied to the two-dimensional Coulomb liquid with finite ion size. The ionic pair distributions, the structure factors, and the thermodynamic functions of the formalism are compared with extensive Monte Carlo simulation results from the literature. At moderate salt densities, our computational approach can accurately describe the thermodynamics of two-dimensional solutions across weak to intermediate coupling strengths. The improved accuracy of the present theory with respect to continuum approaches stems mainly from its ability to account for the non-uniform screening of electrostatic interactions associated with the impenetrability of the charged hard disks by their ionic atmosphere. Due to the underestimation of the ionic clusters emerging in the dilute regime, the validity domain of our self-consistent formalism shrinks with the decrease of the salt density. As a result, our approach cannot reach the critical coupling domain where the conductor–insulator transition of two-dimensional charged hard disks occurs. This indicates that approaching the low-temperature dielectric phase via the present formalism will require extending the underlying self-consistent approximation at least to the next cumulant order.

Composite colloidal assembly by critical Casimir forces

We investigate the phase behavior of mixtures of two populations of colloidal particles dispersed in a binary solvent system near its critical composition. The surfaces of particles are chemically modified to elicit a specific solvent affinity for one of the solvents. In this way, fluid-mediated interactions, which involve the critical Casimir effect, become particle population specific. As a result, the colloidal mixture shows a complex crystallization behavior reminiscent of the crystallization of atomic alloys. We show that the exquisite temperature dependence and reversibility of the critical Casimir interaction allow sampling of the entire phase diagram of the binary system and can even be used to anneal the crystalline microstructure, analogous to temperature cycling in atomic alloy phases.