Browse Articles

A hybrid model integrating RoBERTa, TF-IDF, and attention mechanism for medical query intent classification

An atomic cluster expansion (ACE) potential for water under extreme conditions

We present a machine learning interatomic potential for water designed to capture its complex multiphase behavior, including both molecular and superionic ice phases. The potential is based on the atomic cluster expansion (ACE) formulation and has been parameterized to enable high-fidelity molecular dynamics simulations of water under extreme conditions, for pressures up to 100 GPa and for temperatures between 500 and 6000 K. A diverse range of configurations was generated through ab initio molecular dynamics (AI-MD) simulations, covering insulating and superionic ice phases, liquid water, and dissociated plasma phase. We demonstrate that the H2O ACE potential accurately reproduces experimental and DFT predicted isotherms and Hugoniots. Crucially, the potential is able to capture the intricate phase behavior of water, including the transition from molecular fluid to the appropriate solid ice phases, and the superionic ice phases. This work provides a robust interatomic potential that can be used for large-scale, accurate simulations of water under extreme thermodynamic conditions.

Partially amorphous iron-copper-nickel sulfides for robust bifunctional electrocatalysis

Steady-state free precession NMR in solids undergoing magic angle spinning

Although nuclear magnetic resonance (NMR) is well established to study crystalline and amorphous solids, such experiments are often challenged in sensitivity and resolution. A common approach to improve both of these is magic-angle spinning (MAS); another potential sensitivity-enhancing technique is Steady-State Free Precession (SSFP), an experiment that applies a train of pulses spaced by short repetition delay times, TR. It has recently been shown that, under certain conditions, SSFP could be a method of choice to tackle wide-line solids NMR. But can SSFP and MAS coexist in the same experiment? This study investigates this matter by re-examining SSFP’s spin dynamics under MAS for an ensemble of isolated spins subject to a time-dependent second-rank interaction. It is found that if SSFP’s interpulse time is rotor-synchronized with the sample spinning rate ωR, then the SSFP MAS response will be like that observed in solutions for identical relaxation parameters. However, without rotor synchronization, the SSFP MAS NMR magnetization behaves non-trivially. If the spin anisotropies are much larger than ωR, no steady state is in fact achieved by a single crystal’s evolution. However, under similar mis-synchronization conditions, a steady state can still arise when considering spins over a powdered sample. The dependence of the ensuing steady state on the strength of the anisotropy and the degree of mis-synchronization is not monotonic; the former shows oscillations arising from a series of Bessel-derived functions, while the latter reflects a number of “resonant” dips given by the TR=π2n+1/ωRn=1,2… condition. A rationalization for these behaviors, together with supporting experimental data, is provided.

Design of sliding mode model predictive dual-loop control through self-learning strategy to mitigate the torque ripple in BLDC motor for electric vehicles

Abstract This study investigates a novel dual-loop control strategy that combines sliding mode and model predictive controllers to reduce torque ripple in high-performance Brushless Direct Current (BLDC) motors, especially for automotive electric vehicle (EV) applications. The proposed control system merges the predictive features of Model Predictive Control (MPC) with the robustness of Sliding Mode Control (SMC), creating a dual-loop structure that optimizes inner-loop current regulation and outer-loop speed control. The cost function is formulated to regulate the d- and q-axis currents, enabling the calculation of the optimal output voltage signal necessary for efficient motor performance. This synergy ensures precise stator current modulation, effectively reducing torque ripple while maintaining superior motor efficiency and stability. Additionally, by incorporating adaptive heuristics and data-driven insights through a hybrid self-learning algorithm combining ANN and fuzzy logic, the SMC-MPC controller can forecast and reduce error rates in the BLDC motor, ensuring smooth torque output with minimal ripple. The performance of the SMC-MPC strategy is thoroughly evaluated through MATLAB/SIMULINK Model-in-the-Loop (MIL) simulations and validated via Hardware-in-the-Loop (HIL) testing. Comparative analysis shows that the proposed controller provides superior results, including a rapid 0.01 s rise time, a minimal 0.001% steady-state error, a 0.02 s settling time, and a peak overshoot of 0.066%, outperforming traditional PID and SMC controllers. Also, the experiments show a 28.57% reduction in torque ripple and efficiency maps, achieving 96.47% maximum efficiency. This endeavor validates that the SMC-MPC controller improves BLDC motor efficiency while extending the operational range of EVs.

Growth of structural lengthscale in Kob–Andersen binary mixtures: Role of medium range order

A central and extensively debated question in glass physics concerns whether a single, growing lengthscale fundamentally controls glassy dynamics, particularly in systems lacking obvious structural motifs such as the Kob–Andersen binary Lennard-Jones (KALJ) model. In this work, we investigate structural and dynamical lengthscales in supercooled liquids using the KALJ model in two compositions: 80:20 and 60:40. We compute the dynamical lengthscale from displacement–displacement correlation functions and observe a consistent growth as temperature decreases. To explore the static counterpart, we use a structural order parameter (SOP) based on the mean field caging potential. While this SOP is known to predict short time dynamics effectively, its bare correlation function reveals minimal spatial growth. Motivated by recent findings that long time dynamics reflect collective rearrangements, we perform spatial coarse-graining of the SOP and identify an optimal lengthscale Lmax that maximizes structure–dynamics correlation. We show that the structural correlation length derived from SOP coarse-grained over Lmax exhibits clear growth with cooling and closely tracks the dynamical lengthscale, especially for A particles in the 80:20 mixture and for both A and B particles in the 60:40 system. Our results reconcile the previously observed absence of static length growth in the KALJ model by highlighting the necessity of intermediate range structural descriptors. Furthermore, we find that the particles with larger structural length growth also correspond to species with latent crystallization tendencies, suggesting a possible link between structural order, dynamics, and incipient crystallization.

Decoding the multifaceted cellular and transcriptomic variations of natural killer cells generated from patients with Parkinson’s disease

Dielectric behavior of propylene carbonate solutions with LiPF6, LiClO4, and LiBF4. I. Dielectric relaxation and Raman spectroscopic study

Dielectric relaxation spectroscopy (DRS) is an evolving technique for extracting molecular-level information on orientational polarization and dielectric relaxation in liquids. It reveals fundamental properties, such as permittivity and dipole moments, essential for characterizing electrolyte solutions. However, the use of DRS for electrolyte analysis often faces challenges, such as low-frequency measurement limits, and difficulties in interpreting and assigning complex overlapping relaxation spectra in practical electrolytes. In this study, using propylene carbonate solutions containing three types of lithium salts as model electrolytes, we measured the salt concentration dependence of the static permittivity—a property with limited experimental reports—and discussed its relation to ionic interactions. In addition, two-dimensional correlation spectroscopy between Raman spectroscopy and DRS was employed to achieve reliable spectral assignments of the DRS spectra. CLSA, a chemometric method, was applied to Raman spectra to confirm experimentally the number of significant components and obtain their formation distribution functions. Combining these results with a modified Cavell equation allowed determination of effective dipole moments that account for environmental effects and reflect the collective behavior and dynamics of chemical species in solution. We experimentally demonstrated the capability of DRS to extract important molecular insights that are difficult to obtain using traditional analytical techniques.

Heterogeneous PMO@MXene nanocomposite: a robust and efficient nanocatalyst for two-component synthesis of highly substituted 2-(aryl)-1H-benzo[d]imidazole derivatives

Abstract In this work, a novel MXene-based nanocomposite, denoted as PMO@MXene, was synthesized for the first time and successfully applied as an efficient heterogeneous catalyst in the green synthesis of 2-(aryl)-1 H -benzo[ d ]imidazole derivatives. This catalyst has been used for the synthesis of new derivatives, which were characterized using 13 CNMR, 1 HNMR, TLC, and mass spectrometry. The hybrid material was fabricated through the integration of periodic mesoporous organosilica (PMO) onto the layered structure of MXene, combining the properties of PMO with the excellent conductivity and catalytic potential of MXene. Comprehensive characterization using XRD, FTIR, FESEM, BET, and HRTEM analyses confirmed the successful formation and structural integrity of the heterogeneous PMO@MXene nanocomposite. The catalytic activity of the PMO@MXene nanocomposite was investigated under mild and environmentally benign conditions, leading to high yields in short reaction times with minimal catalyst loading. Notably, the catalyst exhibited remarkable reusability over multiple cycles with negligible loss of performance. This study introduces the PMO@MXene nanocomposite as a promising, sustainable, and recyclable platform for efficient organic transformations, particularly for the synthesis of biologically significant benzimidazole scaffolds.

Dielectric behavior of propylene carbonate solutions with LiPF6, LiClO4, and LiBF4. II. Molecular dynamics simulation study

Propylene carbonate (PC) solutions with three different lithium salts (LiPF6, LiClO4, and LiBF4) were investigated by combining experimental dielectric relaxation spectroscopy (DRS) and molecular dynamics (MD) simulations. Although DRS spectra include rich information regarding microscopic structure and local dynamics in solution systems, the interpretation of spectra is not straightforward and needs complementary analysis. In this work, we applied MD simulations to the PC solutions and demonstrated that the experimental spectra are well reproduced by MD. The simulation results display the decomposed signals, which, respectively, correspond to individual components such as PC and ion pairs. The signal decomposition enables the quantification of essential variables such as rotational relaxation time and relaxation intensity for each component. In addition, the effective dipole moments of individual components were estimated based on the Cavell equation and the simulated results, which agree well with the effective dipole moments obtained from experimental data. It was also shown that the effective dipole moments for some species are smaller than their corresponding unit dipole moments derived from atomic charges and coordinates. This reflects the fact that DRS spectra capture the collective motion of dipoles in solution systems.

High-dimensional continuous action space control via trust region optimized deep reinforcement learning

Highly regioselective cyclodehydrogenation reactions of tetraphenyldibenzoperiflanthene (DBP) on metal substrates

Regioselective cyclodehydrogenation reactions enable the direct, high-efficiency construction of complex multi-ring structures. Tetraphenyldibenzoperiflanthene (DBP), an exceptional organic semiconductor, exhibits promising applications predominantly for high-performance organic optoelectronic devices. Although significant progress has been made in DBP research, the cyclodehydrogenation behavior of DBP on metal surfaces has, to our knowledge, not been reported. Here, we reported the high regioselectivity of DBP molecules during cyclodehydrogenation reaction process on both Au(111) and Ag(111) substrates. In particular, DBP molecules initially form two highly regioselective intermediates after the first-stage annealing. During the second-stage annealing, these intermediates convert to four final products, exhibiting yields exceeding 96% on Au(111) substrates and over 98% on Ag(111) substrates, respectively. Using high-resolution scanning tunneling microscopy and density functional theory calculations, we clearly resolved the atomic structural characteristics of the resulting cyclodehydrogenation products. The calculated total energies of these four main products are substantially lower than those of the other rare products, and this energy trend is in qualitative agreement with our experimental observations. Furthermore, using scanning tunneling spectroscopy, we provided insights into the differences in the electronic properties of DBP before and after selective cyclodehydrogenation. Our work elucidates the selective cyclodehydrogenation of a model single-reaction system on metal surfaces at the atomic scale, which may provide a framework for understanding the surface chemical processes undergone by other reactants.

Elemental and biomolecular changes in serum as indicators of SPION action in the body: analysis using TXRF, FTIR and Raman spectroscopy

Reaction dynamics and isotope effects in the D + CD4 → D2 + CD3 reaction

The H + CH4 reaction and its isotopic variant reactions serve as a benchmark reaction system to understand the dynamics of polyatomic reactions. In this paper, we report a vibrationally state-resolved crossed molecular beam study on the D + CD4 → D2 + CD3 reaction using the time-sliced velocity map ion imaging method. Pronounced collision energy dependence is found in product kinetic energy distributions and angular distributions. At 0.67 eV, CD3 products are dominantly distributed in the backward direction with D2 products in the vibrational ground state. As collision energy increases, the angular distributions of CD3 products shift from the backward direction to the sideways and forward directions, and vibrational excited D2 appears and intensifies. By comparing our result of the D + CD4 → D2 + CD3 reaction with previous studies on the D + CH4 → HD + CH3 and H + CD4 → HD + CD3 reactions, isotope effects have been discussed. The product kinetic energy and angular distributions vary significantly among the three isotopic variant reactions.

Method for label-free & non-destructive detection of microplastics in human formalin-fixed paraffin-embedded tissue sections

Solvation of lithium iodide cluster cations via bridging diamine coordination

Diamines are well-known bidentate ligands that coordinate with metal cations; however, their solvation behavior with ionic clusters remains largely unexplored. In this study, we investigated the structures of lithium iodide ionic clusters solvated by ethylenediamine and N,N,N′,N′-tetramethylethylenediamine using electrospray ionization(ESI)–ion mobility spectrometry–mass spectrometry. Interestingly, diamines were found to stabilize ionic clusters by bridging two metal cations, even though such structures are not the most thermodynamically stable in the gas phase. We propose that these bridging structures were likely formed and kinetically trapped in the solution phase or in the highly concentrated droplets generated during the ESI process. Furthermore, we analyzed the effects of alkali metal and halide identity on solvation behavior.

AI meets endodontics a deep learning approach to precision diagnosis

Origin of normal stress difference in consolidating strong depletion gels

In this study, we employ large scale numerical simulations complemented by a micromechanical model to investigate the consolidation process of a strong depletion gel. We clearly demonstrate that the origin of the normal stress difference in such depletion gel systems is a direct consequence of the mechanical anisotropy in the force networks, which cannot be captured by traditional continuum models that start with a stress-free reference state. The history-dependent nonlinear effects of prestress are better captured by tracking the evolution of essential state parameters, such as force anisotropy, mean normal force, and the average bond number, which govern different aspects of the consolidation process. A simple micromechanical constitutive relationship is proposed between the different stress tensor components and the internal state parameters, which is in excellent agreement with the simulation observations. Intriguingly, our findings strongly indicate the dominance of particle length scale phenomena in dictating the mechanical response of the consolidating depletion gel. This observation directly contradicts the existing literature’s assumption, namely, that a characteristic cluster length scale larger than the particle length scale determines the mechanical response.

Respiratory deposition of particulate matter in Delhi: a five-year assessment of exposure patterns and health risks

State-selective fragmentation of singly ionized HNCS: Experiment and theory

We report a combined experimental and theoretical investigation into the fragmentation dynamics of the HNCS+ ion formed by single photon ionization, with relevance to its possible occurrence in astrochemical environments. Using valence electron–ion coincidence spectroscopy at He Iα (21.22 eV) and He IIα (40.81 eV) photon energies, along with complementary threshold photoelectron–photoion coincidence data, we identify electronic state specific dissociation channels involved in the molecular breakup. Electron spectra correlated with individual fragment ions form the basis of a breakdown diagram and, in conjunction with the valence photoelectron spectrum of HNCS, lead to the observation of an energy-dependent predissociation process. High-level calculated dissociation limits and cuts through the six-dimensional potential energy surfaces of the electronic states of the HNCS+ cation are compared to the experimental data. This makes it possible to suggest the unimolecular fragmentation pathways undergone by HNCS upon ionization and provides new kinetic information on HNCS+ ions, which will contribute to the refinement of astrochemical reaction network models. In particular, sulfur-containing species such as HNCS are increasingly recognized as potential tracers, for instance, in the atmospheres of M-dwarf exoplanets, where sulfur chemistry may play a key role in defining planetary habitability.