Browse Articles

Electron spin–torsion coupling in open shell molecules displaying a large amplitude torsional motion

Following a recent publication by Coudert et al., Phys. Rev. Lett. 134, 173001 (2025), where the electron spin-torsion coupling was theoretically and experimentally evidenced for the first time, an effective fitting Hamiltonian is retrieved for modeling the high-resolution spectrum of non-rigid 2Σ open-shell molecules displaying internal rotation of a methyl group. A molecular Hamiltonian in which the nuclear and electronic degrees of freedom are treated simultaneously is first derived and includes the mass polarization and translational energy terms. The operator describing the new electron spin-torsion coupling is deduced, and an effective 4-D Hamiltonian allowing us to treat simultaneously the fine interaction and the large-amplitude torsional motion is selected and accounts for the electron spin–rotation, the rotation–torsion, and the electron spin–torsion couplings. The procedure to be used for computing electron spin–rotation–torsion energy levels is presented, and the effects of the electron spin–rotation and spin–torsion couplings are numerically investigated. The unreduced effective 4-D fitting Hamiltonian accounting for distortion effects is built using symmetry considerations.

Navigating the mind: investigating the complex relationship between mind-wandering and daydreaming

Abstract Mind-wandering and daydreaming are often treated as synonymous in the literature, yet it remains unclear whether they represent the same cognitive phenomenon in everyday experience. Although mind-wandering and daydreaming are used interchangeably, there are reasons to argue that they relate to two different cognitive phenomena. This study aimed to investigate the differences and similarities between mind-wandering and daydreaming. Using an experience sampling method, participants reported episodes of mind-wandering and daydreaming ten times daily at fixed intervals over seven days. We compared these episodes in terms of phenomenological characteristics and their relative frequency of occurrence. The observed differences were consistent across participant-level analyses and episode-level mixed-effects models, supporting the distinction between mind-wandering and daydreaming as related but separable cognitive phenomena. The stage 1 protocol for this Registered Report was accepted in principle on 22/01/25. The protocol, as accepted by the journal, can be found at: https://doi.org/10.6084/m9.figshare.28945814

Central-barrier dynamics in HCl dissociative chemisorption on Pt(111): Transition state bond elongation as a geometric indicator of vibrational efficacy

We present the first six-dimensional quantum dynamics study of HCl dissociative chemisorption on Pt(111) based on an accurate neural network potential energy surface. The transition state H–Cl bond is stretched by Δr = 0.40 to 2.82 bohr, significantly shorter than those for HCl on Au(111) and Ag(111). This places HCl/Pt(111) in a distinct central barrier regime, leading to two atypical outcomes. First, unlike on Au(111) or Ag(111), where the top site is two orders of magnitude less reactive, the dissociation probability at the top site on Pt(111) is comparable to that at other sites. Second, translational energy is consistently more effective than vibrational excitation, with vibrational efficacy η < 1 for v = 1 and 2 across the entire total energy range. In contrast, rotational effects remain unaffected, showing the same helicopter preference and reduced rotational efficacy as on monometallic surfaces. By comparing eleven HCl + metal systems, we reveal a clear quantitative trend. When Δr is 0.40–0.50 bohr, η remains below unity. When Δr reaches 1.32 bohr, η is always above unity. This provides a geometric rationalization of Polanyi’s early/late dichotomy.

Age-dependent associations between asymmetric cumulative knee adductor load and medial meniscus extrusion

Abstract This study aimed to investigate the differences in medial meniscus extrusion (MME) between lower limbs with higher and lower loading in healthy young and elderly individuals. Sixty-two participants (young, n = 31; elderly, n = 31) were enrolled. The increase in MME (ΔMME) was calculated as the difference between supine and one-leg standing positions evaluated by ultrasonography. The knee adduction moment impulse was calculated using a three-dimensional motion analysis system synchronized with force plates. The cumulative knee adductor load (CKAL) was calculated as the product of the impulse and daily steps. Lower limbs were referred to the ‘lower’ and ‘higher’ sides based on CKAL value and the asymmetry index (ASI) of CKAL was calculated. In only the elderly group, a significant difference in ΔMME between the limbs (lower, 0.3 ± 0.2 mm; higher, 0.6 ± 0.3 mm, p  < 0.01) was observed. The interaction between CKAL and ASI was associated with ΔMME from the linear mixed model (B = 0.09, 95% confidence intervals = 0.02–0.15, 1 SD increment for both values) in the elderly group. These findings indicate that asymmetric knee joint loading is associated with greater meniscal extrusion in elderly individuals.

Membrane permeation by NAF144–67 is determined by C-terminal electrostatics and N-terminal insertion

Cell penetrating peptides are short peptides that permeate cell membranes without the assistance of protein channels or pumps. NAF144–67 is an anti-cancer peptide that selectively permeates cancer cell membranes and permeates membranes to a greater extent when more negatively charged phospholipids are present in the phospholipid bilayer. Computational studies have shown that NAF144–67 directly traverses the membrane, assisted by membrane structural defects caused by the phospholipid headgroups. A mechanistic question is the order of events during permeation. Does the N-terminus permeate before the C-terminus, as suggested by the simulations? We attached the fluorophore dansyl to the N- and C-termini of NAF144–67. Fluorescence spectroscopy was used to probe whether each terminus of NAF144–67 interacts with the polar headgroup or hydrophobic tails of phospholipids in large unilamellar vesicles composed of phosphocholine, phosphoethanolamine, phosphoserine, sphingomyelin, and cholesterol with lipid compositions mimicking normal and cancer cell plasma membranes. To further examine mechanistic events during peptide translocation across membranes, three tryptophan mutants were prepared, and the depth of peptide insertion was evaluated by monitoring the extent of tryptophan fluorescence quenching using phosphocholine lipids brominated at various positions to probe the role of the glycerol backbone or phospholipid tails. We also quantified peptide permeation into normal and cancer cell membranes through a mass spectrometry-based trypsin cleavage assay. Molecular dynamics simulations predicted the location of specific residues within NAF144–67 when embedded in normal and cancer membranes. These methods demonstrate that NAF144–67 binds negatively charged phospholipid headgroups with its positively charged C-terminus, inserts its hydrophobic N-terminus into the lipid interior, and is selective toward cancer model membranes.

Bioglass content determines the physicochemical mechanical and biological performance of chitosan gelatin reduced graphene oxide scaffolds

Seeking an industry role after your PhD? Make sure your CV reflects that

Looking for a double-hybrid recipe to accurately predict spin-state energy gaps of transition metal complexes

We assess the performance of double-hybrid density functionals for spin-state energetics and state ordering in transition-metal complexes using the SSE17 dataset composed of 17 experimental references. Among the eight double hybrids examined, B2-PLYP emerges as the only approach combining robust accuracy and reliability, particularly for the challenging spin-crossover (SCO) complexes. By analyzing the interplay between exact-like exchange (EXX) and PT2 correlation contributions, we show that successful double hybrids follow a quadratic relation between the two fractions (ac=ax2). Finally, an analysis of a representative iron SCO complex further reveals that increasing PT2 correlation and/or decreasing EXX enhances ligand-to-metal σ-donation, highlighting the need for a balanced treatment of both terms.

Group-cross-validated machine learning benchmarking of a Pd-CsW1.6O6/g-C3N5 photocatalyst demonstrates the need for designed experiments in multi-objective optimisation

A Lanczos-based algorithm for the analysis of NMR spin–spin coupling constants in terms of pairs of occupied and virtual orbitals: The Fermi-contact term at the RPA level of theory

The analysis of indirect nuclear spin–spin coupling constants in terms of contributions from localized molecular orbitals is a commonly used approach for gaining a deeper understanding of experimentally observed trends in these couplings. In the vast majority of these studies, contributions from pairs of one occupied and one virtual orbital are calculated and analyzed. Analyses in terms of two pairs of an occupied and a virtual orbital, which would allow for the study of coupling pathways, are much more seldom, as they require calculating the coupling constants as a sum over all excited states. Previous studies have shown that, for the often dominating Fermi-contact contribution to the coupling constants, more or less all excited states have to be calculated when employing a Davidson algorithm, because the most high-lying excited states can also make a significant contribution to the Fermi-contact term. In this study, we investigated therefore, whether by employing a Lanczos algorithm, one can obtain converged values of the Fermi-contact contribution to the indirect nuclear spin–spin coupling constants already with a significantly smaller percentage of the total number of excited states included in the sum-over-states expression. To this purpose, we have extended the recent implementation of a Lanczos algorithm in the Dalton program. The new procedure was tested on 17 molecules containing first, second, and third row atoms. We find that, for most coupling constants, less than 50% of the excited pseudo states are necessary for converging the Fermi-contact term with an error of <0.5 Hz. For the few exceptions, typically for molecules with third-row atoms, around 60% were necessary.

Discrepancies between insertion and target gain are associated with hearing aid abandonment in Chilean older adults

My research on mice is causing me stress. How can I become more resilient?

Size-dependent stability of pesticides adsorption on nanoplastics: Microsecond atomistic-scale molecular dynamics simulations

Microsecond atomistic-scale molecular dynamics simulations were performed to compare the size-dependent adsorption stability of different pesticides on nanoplastic (NP) particles. Spherical particles of atactic polystyrene with diameters of 1.7–5.0 nm, representing NP particles in the final stage of polymer waste degradation, were considered. The results showed stable adsorption at 5 nm NP particle, while the desorption frequency of the least stable 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid (DCVA) pollutant increases exponentially with decreasing nanoparticle diameter as indicate 1 μs simulations. The binding energy of pesticides to the smallest considered NP particle increases as cypermethrin < PCB-169 < DDT < alpha-cyano-3-phenoxybenzyl alcohol (PBA) < DCVA, with only one desorption event observed for cypermethrin. For the 5.0 nm NP particle, however, this order changed, and no desorption occurred during 1 μs simulations, even for the least stable molecules (PBA and DCVA). This underscores the key role of NP size during microplastic degradation in the stability of pollutant adsorption.

Network architecture determines delay robustness in the spindle assembly checkpoint

Abstract The spindle assembly checkpoint (SAC) ensures accurate chromosome segregation during mitosis by preventing premature activation of the anaphase-promoting complex/cyclosome (APC/C). Despite its critical role in maintaining genomic stability, most mathematical models of the SAC treat underlying biochemical processes as instantaneous, neglecting experimentally observed delays arising from molecular activation, complex assembly, and intracellular transport. How such temporal structure interacts with network architecture to shape checkpoint dynamics remains unclear. Here, we develop a distributed-delay framework and incorporate experimentally motivated delays into multiple mechanistic SAC architectures. Using a gamma-chain formulation, we perform systematic stability and bifurcation analyses across representative models. We find that biologically realistic delays fundamentally reorganize system dynamics, partitioning SAC architectures into two distinct classes: delay-robust designs that preserve strong APC/C inhibition, and delay-sensitive designs in which checkpoint control collapses. Motivated by this classification, we introduce a bistable template architecture that combines mechanistic Mad2 templating with an autocatalytic feedback loop. This design maintains bistability and high inhibition across a broad range of physiological delays and remains resilient under stochastic perturbations. These results identify network architecture as a key determinant of robustness to molecular timing and demonstrate that distributed delays can stabilize, rather than destabilize, checkpoint function by enabling temporal integration and memory-like behavior. More broadly, this work establishes delay-aware design principles for biochemical decision-making systems in which intermediate processes are intrinsically time-distributed.

Spiral, target, stripe, and disordered waves in active six-state Potts models

Wave propagation can be observed in various nonequilibrium systems. In this study, we investigated the properties of several wave modes in active six-state Potts models using Monte Carlo simulations of square and hexagonal lattices. Disordered and spiral (SP) waves of six states are formed under weak and strong repulsions at nonflip contacts, respectively. The target (TG) and stripe (ST) waves were found to emerge under stronger repulsion. These three wave modes (SP, TG, and ST) can temporally coexist in small systems near the transition points, but they do not switch in large systems or far from these transition points. During coarsening from randomly mixed states to ST waves, SP waves appear at an intermediate stage. The SP wave modes of three even- or odd-numbered states (states s = 0, 2, 4 or s = 1, 3, 5) emerge under two conditions: repulsion at the diagonal contact and attraction at nonflip contacts. Previously thought to be identical for both conditions, the wave types were found to differ, comprising forward and backward waves (s = 1 → 3 → 5 → 1 or s = 1 → 5 → 3 → 1), whose domain boundaries move by the two-step and four-step forward flips, respectively. The transition between the waves of the even- and odd-numbered states is first-order for both the forward and backward waves.

Epidemiology and clinical outcomes of von Hippel-Lindau disease in Korea: a nationwide cohort study

Constructing density functional tight-binding parameters for electronic structure modeling of lead-bromide perovskites, perovskitoids, and related structures

Density functional tight-binding (DFTB), a semi-empirical approach rooted in density functional theory, is well-suited for simulating large periodic systems. Following Jiang et al. [Phys. Rev. Mater. 9, 023803 (2025)], we have specifically tailored DFTB parameters for accurate electronic bandgap calculations in both three-dimensional and two-dimensional lead bromide perovskites, significantly reducing computational costs compared to conventional ab initio methods. Our electronic DFTB parameters provide reliable predictions for key electronic properties, such as bandgaps and effective masses, closely matching existing experimental data and advanced many body perturbation theory calculations. Furthermore, our approach successfully captures the bandgap trends observed in mixed-halide perovskites, reflecting the variation with halide composition. In addition, we explore the transferability of the newly optimized DFTB parameters to predict the electronic properties of a variety of low-dimensional perovskites and related structures with edge- or face-sharing octahedra.

Pose estimation analysis of free-play reveals atypical interpersonal motor synchrony in autism

Abstract Socio-motor behaviours, such as interpersonal motor synchrony (IMS), are widely thought to be atypical in autism but remain difficult to quantify objectively across the full spectrum of functioning and development. Existing studies have largely relied on controlled paradigms with seated, older participants, constraining movement and limiting insight into naturalistic interactions, particularly in young children. We analysed 69 autistic and 32 typically developing (TD) children aged 14–46 months during free-play segments of ADOS-2 diagnostic sessions. To measure IMS between child–assessor dyads, we developed a two-stage pipeline integrating identity tracking (SAM 2.1) and pose estimation (RTMPose) to extract frame-level skeletal coordinates. IMS was operationalised using dynamic time warping (DTW). Dyads involving autistic children exhibited lower IMS than TD dyads, in both trunk and head regions. Members of dyads with autistic children also showed greater activity and speed variability. Critically, IMS reductions were associated with movement characteristics of both partners in TD dyads, but primarily with child movement in dyads with autistic children, suggesting a more asymmetric coordination pattern. Lower IMS was further associated with higher autistic traits and lower cognitive functioning. These findings highlight the potential of pose estimation and DTW as scalable, non-invasive tools for quantifying atypical IMS and supporting more precise autism phenotyping in naturalistic settings.

Spin–cavity interactions in relativistic Jahn–Teller systems under strong light–matter coupling

We extend our recent work on the cavity-modified spin Zeeman effect of an effective spin-1/2-system [E. W. Fischer and M. Roemelt, J. Chem. Phys. 163, 174307 (2025)] to a relativistic Jahn–Teller scenario under strong light–matter coupling. Here, the effective spin-1/2-system is realized via a single electron or a single hole in a doubly degenerate molecular orbital system of trigonal symmetric transition metal complexes. Single-particle and single-hole systems are subject to both vibronic and spin–orbit coupling (SOC) augmented by interactions with a quantized cavity field via the cavity–Zeeman interaction. Methodologically, we combine the relativistic E × e-Jahn–Teller model with a recently introduced effective Hamiltonian formalism based on quasi-degenerate perturbation theory, which treats the cavity–spin interaction in leading order beyond the dipole approximation. We derive analytic expressions for Kramers pair energies in weak and strong SOC regimes, as well as related cavity-modified effective electronic g-factors. We find cavity-induced modifications of the electronic g-factor to become relevant in the weak SOC regime for both single-particle and single-hole systems while being effectively quenched under strong SOC. Alternating signs of the cavity–Zeeman correction render single-particle and single-hole scenarios distinct in their response to the cavity field from a g-factor perspective.

Comparing the effect of selenium yeasts, betaine, and capsaicin on heat stress response in fattening bulls

Abstract Prolonged high temperatures cause heat stress in fattened cattle, negatively affecting growth and health. This study evaluated dietary supplements in Limousin bulls under mild heat stress (THI = 75.01 ± 4.13). Forty-eight bulls were divided into four groups, receiving either a standard TMR or TMR supplemented with selenium yeast (YSE), betaine (BET), or capsaicin (CAP) for 60 days. Results showed all additives improved daily gains ( p  ≤ 0.05). Redox markers varied; total antioxidant capacity (TAC) was highest in the control group, while BET had the lowest. The BET also showed the highest GPx activity ( p  ≤ 0.01). Heat shock protein (HSP70) concentrations were elevated in YSE and BET compared to CON and CAP. Lymphocyte content decreased in YSE and BET. The CAP reduced calcium and creatinine levels ( p  ≤ 0.05). Feeding behavior differed, with CON and CAP having longer feeding times, while YSE and BET spent more time resting ( p  ≤ 0.01). The BET and YSE provided the greatest economic benefits, while the higher cost of CAP reduced its economic advantage despite improved production performance. In conclusion, all supplemented additives were effective under mild heat stress. The factor limiting the practical use of capsaicin compared to other additives may be its price. Further research is needed on the interaction of these supplements for practical application.