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In this work, hydrogen diffusion behavior and mechanisms in the 4130X steel influenced by temperature, locally high concentration, and grain boundary were studied by leveraging both electrochemical hydrogen permeation experiments and molecular dynamics simulations. It was revealed that the hydrogen diffusion coefficient of the 4130X steel was increased with increasing temperature and decreasing locally high hydrogen concentration. The grain boundaries with misorientation below 15° characterized by an electron backscatter diffraction map were identified as hydrogen trapping sites, thus rendering a lower mean square displacement of hydrogen atoms and localized hydrogen diffusion trajectories. Furthermore, at a high hydrogen concentration of 4 at. %, these grain boundaries were saturated by hydrogen atoms, and platelet-like hydrogen clusters were formed within the lattice, which further inhibited the diffusive motion of hydrogen atoms. These findings would deepen our understanding of hydrogen embrittlement mechanisms by establishing the connections between macroscopic permeation behavior and atomic-scale hydrogen diffusion in structural materials. [ABSTRACT FROM AUTHOR]

The microwave spectra of three isotopologues of the gas-phase heterodimer formed between cis-1,2-difluoroethylene and hydrogen chloride are obtained in the 5–21 GHz region using Fourier transform microwave spectroscopy. The molecular structure, determined from the analysis of the spectra and supported by quantum chemistry calculations, has the hydrogen atom of the hydrogen chloride molecule interacting with both fluorine atoms of the fluoroethylene and no interaction between the chlorine atom and the olefin. Although the equilibrium structure has two inequivalent H⋯F interactions, zero-point motion averages over the two equivalent choices for these interactions, rendering the pairs of like atoms (C, H, and F) of the fluoroethylene equivalent, retaining the C2v symmetry of the olefin. This results in only one unique singly substituted 13C isotopologue and in the observed effects on transition intensities due to nuclear spin statistics. The heterodimer structure allows for a strong, linear hydrogen bond between the HCl donor and the fluoroethylene acceptor that is more important here than in the analogous acetylene containing complex, where the interaction between the π electrons of acetylene and an electrophilic hydrogen atom on the olefin compensates for the loss of linearity required for binding to a geminal F/H pair. [ABSTRACT FROM AUTHOR]

In this contribution, we investigate the formation and dissociation of boron–hydrogen (BH) pairs in crystalline silicon under thermal equilibrium conditions. Our samples span doping concentrations of nearly two orders of magnitude and are passivated with a layer stack consisting of thin aluminum oxide and hydrogen-rich silicon nitride (Al 2 O 3 /SiN x :H). This layer stack acts as a hydrogen source during a following rapid thermal annealing. We characterize the samples using low-temperature Fourier-transform infrared spectroscopy and four-point-probe resistivity measurements. Our findings show that the proportion of hydrogen atoms initially bound to boron (BH pairs) rises with increasing boron concentration. Upon isothermal dark annealing at (163 ± 2) °C, hydrogen present in molecular form, H 2 , dissociates at a rate directly proportional to the concentration of boron atoms, ∝ [ B − ], leading to the formation of BH pairs. With prolonged annealing, an unknown hydrogen complex is formed at a rate that is inversely proportional to the square of the boron concentration, ∝ 1/[B − ] 2 , resulting in the disappearance of BH pairs. Based on experimental observations, we derive a kinetic model in which we describe the formation of the unknown complex through neutral hydrogen H 0 binding to a sink. Additionally, we investigate the temperature dependence of the reaction rates and find that the H 2 dissociation process has an activation energy of (1.11 ± 0.05) eV, which is in close agreement with theoretical predictions. [ABSTRACT FROM AUTHOR]

The effects of hydrogen absorption on the local lattice structure in palladium (Pd) were investigated by means of positron annihilation lifetime spectroscopy (PALS) and time-differential perturbed angular correlation (TDPAC) spectroscopy. The PALS measurements demonstrated that dislocations and vacancies formed in the preparation process of a pristine Pd plate can be clearly removed by vacuum annealing at 1073 K and the subsequent absorption of a large quantity of hydrogen, resulting in the production of the β-phase hydride PdH0.62, induces the formation of the open-volume defects again. It was also found that the absorbed hydrogen atoms remain in the Pd sample at 323 K but they are completely evacuated during 5 h heating at 383 K. In addition to the overall thermal behavior, an atomic scale observation of the hydrogen dynamics was carried out by means of TDPAC spectroscopy, indicating the nuclear quadrupole relaxation of the present (111m,111Pd → 111Ag→)111Cd probe, which evidently suggests that the hydrogen atoms show fast dynamic motion around the probe. From the temperature-dependent nuclear quadrupole relaxation rate, we obtained an activation energy of 41(4) meV for the motion. [ABSTRACT FROM AUTHOR]

In the past decade, natural orbital functional (NOF) approximations have emerged as prominent tools for characterizing electron correlation. Despite their effectiveness, these approaches, which rely on natural orbitals and their associated occupation numbers, often require hybridization with other methods to fully account for all correlation effects. Recently, a global NOF (GNOF) has been proposed [Piris, Phys. Rev. Lett. 127, 233001 (2021)] to comprehensively address both dynamic and static correlations. This study evaluates the performance of GNOF on strongly correlated model systems, including comparisons with highly accurate Full Configuration Interaction calculations for hydrogen atom clusters in one, two, and three dimensions. Additionally, the investigation extends to a BeH2 reaction, involving the insertion of a beryllium atom into a hydrogen molecule along a C2v pathway. According to the results obtained using GNOF, consistent behavior is observed across various correlation regions, encompassing a range of occupations and orbital schemes. Furthermore, distinctive features are identified when varying the dimensionality of the system. [ABSTRACT FROM AUTHOR]

Chirality ubiquitously appears in nature; however, its quantification remains obscure owing to the lack of microscopic description at the quantum-mechanical level. We propose a way of evaluating chirality in terms of the electric toroidal monopole, a practical entity of time-reversal even pseudoscalar (parity-odd) objects reflecting relevant electronic wave functions. For this purpose, we analyze a twisted methane molecule at the quantum-mechanical level, showing that the electric toroidal monopoles become a quantitative indicator for chirality. In the twisted methane, we clarify that the handedness of chirality corresponds to the sign of the expectation value of the electric toroidal monopole and that the most important ingredient is the modulation of the spin-dependent imaginary hopping between the hydrogen atoms, while the relativistic spin–orbit coupling within the carbon atom is irrelevant for chirality. [ABSTRACT FROM AUTHOR]

Born–Huang expansion is the cornerstone for studying potential energy surfaces and non-adiabatic couplings (NACs) in molecular systems. However, the traditional approach is insufficient to describe the molecular system, which strongly interacts with quantum light. Inspired by the work by Schäfer et al., we develop the generalized Born–Huang expansion theory within a macroscopic quantum electrodynamics (QED) framework. The theory we present allows us to describe electromagnetic vacuum fluctuations in dielectric media and incorporate the effects of dressed photons (or polaritons) into NACs. With the help of the generalized Born–Huang expansion, we clearly classify electronic nuclear NACs, polaritonic nuclear NACs, and polaritonic electronic NACs. Furthermore, to demonstrate the advantage of the macroscopic QED framework, we estimate polaritonic electronic NACs without any free parameter, such as the effective mode volume, and demonstrate the distance dependence of the polaritonic electronic NACs in a silver planar system. In addition, we take a hydrogen atom in free space as an example and derive spontaneous emission rates from photonic electronic NACs (polaritonic electronic NACs are reduced to photonic electronic NACs). We believe that this work not only provides an avenue for the theoretical exploration of NACs in a nucleus–electron–polariton coupled system but also offers a more comprehensive understanding for molecules coupled with quantum light. [ABSTRACT FROM AUTHOR]

Realization of microwave-absorbing materials with "small thickness, light weight, broad bandwidth, and low reflectivity" is an invariable topic. In this paper, Sm2Fe14BHx/polyurethane (SFBH/PU) composites with planar anisotropy were prepared by reduction–diffusion (R/D) and water bath hydrogenation (WBH) process. A minimum reflection loss (RL) value reaches −59.7 dB at the perfect matching frequency of 13.79 GHz with a thickness of only 1.035 mm. Compared with unhydrogenated SFB, the bandwidth and reflectivity are significantly improved. It is mainly attributed to the fact that introduction of hydrogen atoms effectively modulates the electromagnetic parameters and increases the Snoek limit ((μ i − 1) f r) , which leads to the improvement of the high-frequency microwave absorption performance. In addition, the bandwidth equation is derived and simplified from the perspective of the reflected wave at the interface, which is in good agreement with the measured results. [ABSTRACT FROM AUTHOR]

It has been assumed that the negative divergence of all stress tensors in common use yields the same force. This work finds that this is untrue, and, in fact, can vary wildly. We demonstrate this for the hydrogen atom, the one-particle isotropic harmonic oscillator, and a particle in an infinite spherical well where the exact density, pair-density, and the first order reduced density matrix are known for ground and excited states without any approximation. The Ehrenfest stress-tensor is introduced as any stress-tensor whose negative divergence will yield the corresponding Ehrenfest force for the same system when the exact wave-function is utilized. Stress-tensors within the literature are examined to show those that are Ehrenfest stress-tensors. Those that differ are demonstrated by how they differ within an exact formulation. The proof that the negative divergence of an Ehrenfest stress-tensor yields the Ehrenfest force is summarized. [ABSTRACT FROM AUTHOR]

Nuclear quantum effects play critical roles in a variety of molecular processes, especially in systems that contain hydrogen and other light nuclei, such as water. For water under ambient conditions, nuclear quantum effects are often interpreted as local effects resulting from a smearing of the hydrogen atom distribution. However, the orientational structure of water at interfaces determines long-range effects, such as electrostatics, through the O–H bond ordering that is impacted by nuclear quantum effects. In this work, I examine nuclear quantum effects on long-range electrostatics of water confined between hydrophobic walls using path integral simulations. To do so, I combine concepts from local molecular field theory with path integral methods at varying levels of approximation to develop efficient and physically intuitive approaches for describing long-range electrostatics in nonuniform quantum systems. Using these approaches, I show that quantum water requires larger electrostatic forces to achieve interfacial screening than the corresponding classical system. This work highlights the subtleties of electrostatics in nonuniform classical and quantum molecular systems, and the methods presented here are expected to be of use to efficiently model nuclear quantum effects in large systems. [ABSTRACT FROM AUTHOR]

This work presents systematic comparisons between classical molecular dynamics (cMD) and quantum dynamics (QD) simulations of 15-dimensional and 75-dimensional models in their description of H atom scattering from graphene. We use an experimentally validated full-dimensional neural network potential energy surface of a hydrogen atom interacting with a large cell of graphene containing 24 carbon atoms. For quantum dynamics simulations, we apply Monte Carlo canonical polyadic decomposition to transform the original potential energy surface (PES) into a sum of products form and use the multi-layer multi-configuration time-dependent Hartree method to simulate the quantum scattering of a hydrogen or deuterium atom with an initial kinetic energy of 1.96 or 0.96 eV and an incident angle of 0°, i.e., perpendicular to the graphene surface. The cMD and QD initial conditions have been carefully chosen in order to be as close as possible. Our results show little differences between cMD and QD simulations when the incident energy of the H atom is equal to 1.96 eV. However, a large difference in sticking probability is observed when the incident energy of the H atom is equal to 0.96 eV, indicating the predominance of quantum effects. To the best of our knowledge, our work provides the first benchmark of quantum against classical simulations for a system of this size with a realistic PES. Additionally, new projectors are implemented in the Heidelberg multi-configuration time-dependent Hartree package for the calculation of the atom scattering energy transfer distribution as a function of outgoing angles. [ABSTRACT FROM AUTHOR]

Polar surfaces undergo polarity compensation, which can lead to significantly different surface chemistry from their nonpolar counterparts. This process in turn can substantially alter the binding of adsorbates on the surface. Here, we find that hydrogen binds much more strongly to the polar (110) surface than the nonpolar (100) surface for a wide range of ABO3 perovskites, forming a hydroxyl layer on the O24− termination and a hydride layer on the ABO4+ termination of the (110) surface. The stronger adsorption on the polar surfaces can be explained by polarity compensation: hydrogen atoms can act as electron donors or acceptors to compensate for the polarity of perovskite surfaces. The relative stability of the surface terminations is further compared under different gas environments and several perovskites have been found to form stable surface hydride layers under oxygen-poor conditions. These results demonstrate the feasibility of creating stable surface hydrides on perovskites by polarity compensation which might lead to new hydrogenation catalysts based on ABO3 perovskites. [ABSTRACT FROM AUTHOR]

Water dissociation on TiO2 surfaces has been known for decades and holds great potential in various applications, many of which require a proper understanding of thermal transport across the TiO2–H2O interface. Molecular dynamics (MD) simulations play an important role in characterizing complex systems' interfacial thermal transport properties. Nevertheless, due to the imprecision of empirical force field potentials, the interfacial thermal transport mechanism involving water dissociation remains to be determined. To cope with this, a deep potential (DP) model is formulated through the utilization of ab initio datasets. This model successfully simulates interfacial thermal transport accompanied by water dissociation on the TiO2 surfaces. The trained DP achieves a total energy accuracy of ∼238.8 meV and a force accuracy of ∼197.05 meV/Å. The DPMD simulations show that water dissociation induces the formation of hydrogen bonding networks and molecular bridges. Structural modifications further affect interfacial thermal transport. The interfacial thermal conductance estimated by DP is ∼8.54 × 109 W/m2 K, smaller than ∼13.17 × 109 W/m2 K by empirical potentials. The vibrational density of states (VDOS) quantifies the differences between the DP model and empirical potentials. Notably, the VDOS disparity between the adsorbed hydrogen atoms and normal hydrogen atoms demonstrates the influence of water dissociation on heat transfer processes. This work aims to understand the effect of water dissociation on thermal transport at the TiO2–H2O interface. The findings will provide valuable guidance for the thermal management of photocatalytic devices. [ABSTRACT FROM AUTHOR]

In a recent study, we developed a kinetic-energy density functional that can be utilized in orbital-free quantum mechanical/molecular mechanical (OF-QM/MM) simulations. The functional includes the nonlocal term constructed from the response function of the reference system of the QM solute. The present work provides a method to combine the OF-QM/MM with a theory of solutions based on the energy representation to compute the solvation free energy of the QM solute in solution. The method is applied to the calculation of the solvation free energy Δμ of a QM water solute in an MM water solvent. It is demonstrated that Δμ is computed as −7.7 kcal/mol, in good agreement with an experimental value of −6.3 kcal/mol. We also develop a theory to map the free energy δμ due to electron density polarization onto the coordinate space of electrons. The free energy density obtained by the free-energy mapping for the QM water clarifies that each hydrogen atom makes a positive contribution (+34.7 kcal/mol) to δμ, and the oxygen atom gives the negative free energy (−71.7 kcal/mol). It is shown that the small polarization free energy −2.4 kcal/mol is generated as a result of the cancellation of these counteracting energies. These analyses are made possible by the OF-QM/MM approach combined with a statistical theory of solutions. [ABSTRACT FROM AUTHOR]

Transparent amorphous oxide semiconductors (TAOSs) are essential materials and ushering in information and communications technologies. The performance of TAOS depends on the microstructures relating to the defects and dopants. Density functional theory (DFT) is a powerful tool to understand the structure–property relationship relating to electronic state; however, the computation of DFT is expensive, which often hinders appropriate structural modeling of amorphous materials. This study, thus, applied machine-learning potential (MLP) to reproduce the DFT level of accuracy with enhanced efficiency, to model amorphous In 2 O 3 (a-In 2 O 3), instead of expensive molecular dynamics (MD) simulations with DFT. MLP-MD could reproduce a-In 2 O 3 structure closer to the experimental data in comparison with DFT-MD and classical MD simulations with an analytical force field. Using the relatively large models obtained by the MLP-MD simulations, it was unraveled that the anionic hydrogen atoms bonding to indium atoms attract electrons instead of the missing oxygen and remedy the optical transparency of the oxygen deficient a-In 2 O 3. The preferential formation of metal–H bonding through the reaction of oxygen vacancy was demonstrated as analogous to InGaZnO x thin films [Joonho et al., Appl. Phys. Lett. 110, 232105 (2017)]. The present simulation suggests that the same mechanism works in a-In 2 O 3 , and our finding on the structure–property relationship is informative to clarify the factors affecting the optical transparency of In-based TAOS thin films. [ABSTRACT FROM AUTHOR]

In this study, reduced graphene oxide (rGO) coatings were fabricated on duplex stainless steel (DSS) substrates using the electrophoretic deposition (EPD) method to evaluate their hydrogen resistance performance. The successful fabrication of rGO coatings was confirmed using Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Photoelectron Spectroscopy (XPS). The structural characteristics were characterized using Raman spectroscopy and X-ray Diffraction (XRD). The results indicate that the EPD voltage is a crucial factor affecting the surface quality of and hydrogen resistance performance of rGO. Lower voltages resulted in lower degrees of rGO reduction and higher surface wrinkle density, while higher voltages caused bubble formation, significantly degrading the coating quality and hydrogen resistance performance. The optimal hydrogen resistance was achieved at an EPD voltage of 7.5V and a deposition time of 6 min. Electrochemical hydrogen charging tests and thermal desorption analysis (TDA) demonstrated that rGO coatings prepared under optimal conditions exhibited excellent hydrogen resistance efficiency, significantly reducing hydrogen atom penetration in hydrogen environments. The study further revealed that bubble formation significantly reduces the hydrogen resistance of rGO, which is attributed to increased interlayer spacing and the loss of the "labyrinth effect". • Electrophoretic deposition (EPD) method can effectively reduce graphene oxide. • Optimal EPD parameters were identified for rGO coatings to enhance hydrogen resistance. • RGO coatings reduced hydrogen penetration by preserving a dense multilayer structure. [ABSTRACT FROM AUTHOR]

Abraham model solute descriptors for 2‑[4-(dibutylamino)-2-hydroxybenzoyl]benzoic acid were determined from the compound’s published solubility data in 10 organic solvents of varying polarity and hydrogen-bonding character. The calculated hydrogen-bond donor descriptor value, A = 0.548, suggests that intramolecular bond formation occurs between the hydrogen atom on the -OH functional group and one of the two lone pairs of electrons on the oxygen atom of the ketone functional group, >C=O, which would result in the formation of a six-membered hydrogen-bonded ring structure. A much larger A-solute descriptor would be expected if the hydrogen atoms of both the -OH and -COOH functional groups were free to engage in intermolecular H-bond formation with surrounding solvent molecules. [ABSTRACT FROM AUTHOR]

Zn metal anode is desired for aqueous batteries due to its high capacity and low redox potential. However, uneven Zn deposition and hydrogen evolution reaction (HER) have hindered the electrochemical reversibility and stability. Herein, an artificial solid electrolyte interphase (SEI) composed of metal center incorporated siloxane coupling with fluoride is in situ generated on Zn surface by a facile “etching–coating” process. This SZ‐SEI provides interaction sites with Zn2+, which helps with its desolvation at the interface and enlarges the transference number. Uniform Zn deposition underneath the layer is thus realized. Meanwhile, the SZ‐component hinders the adsorption of hydrogen atom and effectively suppresses HER. Thanks to the above effects, the cycle life of symmtric cells with SZ‐Zn electrodes extends to 2200 and 1400 h at the current densities of 10 and 20 mA cm−2, respectively. The coulombic efficiency of Zn plating/stripping also reaches 99.8% for 3800 cycles. In addition, the SZ‐Zn anode enables better rate capability and cycling stability of full cells. [ABSTRACT FROM AUTHOR]

Background: Esketamine, the first Food and Drug Administration-approved fast-acting antidepressant, has limited use because of its addictive properties. Although the combination of dextromethorphan and bupropion partially addresses the limitations of esketamine, concerns remain regarding neurologic side effects related to dextromethorphan metabolites, and seizure risks associated with high-dose bupropion. SAL0114, a novel formulation combining deuterated dextromethorphan (in which hydrogen atoms are replaced with deuterium) with bupropion, seeks to enhance dextromethorphan stability through deuteration of its metabolic sites. This approach is expected to increase antidepressant efficacy, reduce metabolite-induced safety issues, and allow for lower bupropion dosages. Methods: Radioligand competition binding assays were used to evaluate the impact of deuterium substitution on the in vitro activity of dextromethorphan and its metabolite, dextrorphan. In vitro hepatic microsomal stability and in vivo mouse pharmacokinetic assays were performed to assess the effects of deuteration on dextromethorphan stability. Two mouse models of behavioral despair were used to determine the antidepressant and synergistic effects of deuterated dextromethorphan and bupropion. Additionally, a reserpine-induced hypothermia rat model and an ammonia-induced cough mouse model were used to assess the in vivo effects from a pathological perspective. Results: Deuterated dextromethorphan maintained the same in vitro activity as dextromethorphan while exhibiting twice the metabolic stability both in vitro and in vivo. Combination with bupropion further improved its in vivo stability, increasing the exposure by 2.4 times. The combination demonstrated efficacy and synergistic effects in all tested animal models, showing superior efficacy compared with the dextromethorphan-bupropion combination. Conclusion: Deuteration improved dextromethorphan metabolic stability without altering its in vitro activity. Bupropion enhanced this stability and synergistically boosted the antidepressant effect by increasing deuterated dextromethorphan exposure in vivo. This enhanced metabolic stability suggests a reduction in dextromethorphan metabolites associated with clinical neurological side effects. Consequently, SAL0114 is hypothesized to offer improved efficacy and safety compared with the non-deuterated combination, potentially allowing for lower bupropion dosages. Further clinical studies are required to confirm these preclinical findings. [ABSTRACT FROM AUTHOR]

We have explored the possibility of forming H⋅ and H 2 from H 2 S, CH 4 , H 2 O and SiH 4 in a series of ab initio calculations. The key finding is that H 2 S can give rise to direct photolytic ultrafast formation of H 2 This finding is in agreement with the available experimental data and is a result of a directed pathway that leads toward H 2 formation at easily accessible wavelengths. It arises at the (conical) intersection between the two lowest-lying electronic states. This intersection is a result of the valence orbital interaction of the two hydrogen atoms. This interaction is becoming more favorable as the S-H bonds simultaneously becomes longer. The H-S σ-σ∗ bonding interaction cannot compete with the bond formation that takes place between the hydrogens as two bonds stretch simultaneously. For oxygen this interaction it predominant. The reason is that sulfur has a higher principal quantum number and the interaction with the 1s of hydrogen therefore is less favorable. The excited states that are involved in the H 2 formation from H 2 S could be populated by, for example, a two-photon 400 nm excitation. The other hydrides have a more entangled potential energy landscape close to the Franck-Condon region in the direction of the reaction coordinate that leads to H 2 loss and as a result the direct loss of a hydrogen atom is favored. A two-photon excitation could be induced by femtosecond laser pulses that at the same time is proposed as a future platform for sensing the H 2 S molecules with the backward transient absorption scheme. The implication would be that both sensing and photoinduced H 2 formation could be in place at the same time which justifies the use of expensive femtosecond light sources getting "two for the price of one". • H 2 S can form H 2 when exposed to two 400 nm photons. • Interaction with short light pulses is predicted in induce non-statistical dynamics in H 2 S and H 2 O. • The findings could be a platform for sensing the H 2 S molecules with the backwards transient absorption scheme. [ABSTRACT FROM AUTHOR]

Niobocene hydride–silyl complexes exhibit intriguing structural characteristics with the potential for direct hydride/silyl exchange, where hydride migration plays a crucial role during conformational interconversion. In this study, quantum chemical calculations were utilized to investigate the transformation pathways involved in hydride/silyl exchange in niobocene trihydride complexes with various dichlorosilanes, including SiCl2Me2, SiCl2iPr2, and SiCl2MePh ligands. The conformational changes and hydride shifts within these niobocene hydride–silyl complexes were examined, and key intermediates were identified. Electronic wavefunction analysis provided insights into the coordination configurations and the nature of inter-ligand interactions. Interaction region indicator (IRI) analysis revealed Van der Waals interactions between chloride atoms and cyclopentadienyl rings, as well as between chloride atoms and Me, iPr, and Ph groups. Notably, distinct interactions between hydride ligands, including those from Si-H moieties and coordinated hydrogen atoms, were observed. Both lateral and central conformations, with respect to silicon coordination to the niobium center, were considered. This study enhances the understanding of intermediate conformations in the hydride/silyl exchange process and provides a detailed characterization of inter-ligand interactions, offering valuable insights for analyzing metallocene complexes with organic ligand coordination. [ABSTRACT FROM AUTHOR]

Characterized by its exceptional electrical, physical, and chemical properties, 1-phenyl-1-xylylethane (PXE) insulating oil finds extensive application in the realm of power capacitor insulation. In this study, molecular simulation is employed to investigate the reactivity of PXE insulating oil molecules and the impact of temperature on water diffusion behavior in PXE insulating oil, as well as its solubility. The findings demonstrate a higher propensity for hydrogen atoms in nucleophilic and electrophilic positions within PXE insulating oil molecules to interact with water molecules. The inclusion of a temperature field enhances the Brownian motion of water molecules and improves their diffusion ability within the oil. Furthermore, the temperature field diminishes the interaction force between water molecules and the oil medium. Under the influence of this temperature field, there is an increase in the free volume fraction of PXE insulating oil, leading to a weakening effect on hydrogen bonds between oxygen and hydrogen atoms within PXE insulating oil. Additionally, with increasing temperature, there is an elevation in moisture solubility within insulating oil, resulting in a transition from a suspended state to a dissolved state. [ABSTRACT FROM AUTHOR]

The scattering dynamics of electron capture in e+$$ {\mathrm{e}}^{+} $$‐H(1 s) scattering under dense semi‐classical plasma (DSCP) environments has been investigated theoretically. Coupled multi‐channel two‐body Lippmann‐Schwinger equations have been solved by retaining e+$$ {\mathrm{e}}^{+} $$+H(1 s) and p + Ps(1 s) channels to calculate the cross sections (CS) of the electron capture process at intermediate and high incident energies. The effective interaction of the plasma charged particles is modelled by a pseudopotential which is a function of two parameters, namely the plasma screening strength and the de Broglie wavelength. A detailed study is made to explore the changes in the CSs of the above‐mentioned process with respect to the variation in the plasma screening strength and de Broglie wavelength. Significant changes are found to take place, when the screening strength and the de Broglie wavelength are varied. Specifically, the sharp minimum in the differential CS moves toward the forward direction with increasing de Broglie wavelength at a given screening strength. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to provide a highly efficient method to obtain the kinetics of the hydrogen evolution reaction (HER) on metal electrodes in an alkaline solution and to analyze the effect of thiourea addition on HER under the same cathodic overpotential. Design/methodology/approach: A novel method based on hydrogen permeation tests, potentiodynamic polarization tests and electrochemical impedance spectroscopy was put forward to characterize the HER kinetics on metal electrode. Findings: The study found that adding thiourea accelerated the Volmer, Heyrovsky and Tafel reactions associated with HER. In addition, it reduced the hydrogen surface coverage and increased the hydrogen permeation steady-state current density. As a result, thiourea facilitated HER, promoted the diffusion of hydrogen atoms into iron and reduced the number of hydrogen atoms in the adsorbed state. Originality/value: This work provides novel insights into the influence of thiourea on HER kinetics, demonstrating that thiourea addition can significantly enhance HER efficiency by altering reaction dynamics and promoting hydrogen atom diffusion into iron. This has implications for hydrogen energy applications, cathodic protection and understanding hydrogen embrittlement mechanisms. [ABSTRACT FROM AUTHOR]

The exchangeability of hydrogen atoms within organic molecules in vivo with ambient water hydrogen is uncertain. We assessed this by administrating the tracer deuterium to the fish. Flatfish were retained in deuterium-elevated seawater for 48 h, and the deuterium-to-hydrogen (D/H) ratios in the flesh samples were measured. Rapid in vivo equilibration between exchangeable organically bound hydrogen (Ex-OBH) and tissue-free water (TFW) hydrogen was indicated by the linear relationship between the D/H ratios of total organically bound hydrogen (t-OBH) and TFW. The estimated ratio of Ex-OBH to t-OBH (fe) in vivo was 7.2 ± 0.0%, while there was no in vivo production rate of non-exchangeable organically bound deuterium (Nx-OBD). In contrast to this estimation of no production of Nx-OBD in vivo , the D/H values of Nx-OBH measured by equilibration in vitro increased, consequently reducing the value of fe in vitro to some extent compared to that of fe in vivo. This indicated that a certain portion of Ex-OBH in vivo was not exchangeable during the equilibration in vitro. [ABSTRACT FROM AUTHOR]

Recently, direct non-oxidative conversion of methane (NOCM) into hydrogen and light hydrocarbons has garnered considerable attention. In our work, we employed a dielectric barrier discharge (DBD) plasma over a GaN/SBA15 catalyst for NOCM. Adding catalyst to plasma remarkably promotes the conversion of CH4, resulting in a significant improvement, for instance, from 27.8 to 39.2%. A systematic investigation of plasma performance at different discharge powers with and without catalyst was conducted. In the case of plasma + 15wt% GaN/SBA15, CH4 conversion reaches an impressive 79.4%. However, it exhibits the lowest selectivity of 14.4% for C2+, while achieving the highest selectivity for hydrogen at 48.9%. Several characterization methods, including XRD, SEM, BET, XPS, and TPO-MS, were used to study the mechanism of the reaction. Plasma electrons and ions can effectively interact with activated CH3 radicals, promoting their adsorption onto Ga sites on the catalyst surface. Simultaneously, hydrogen atoms adsorb onto neighboring N atoms, rapidly delocalizing to produce H2, and the delocalization of hydrogen atoms in C species leads to the formation of species like CxHy. This study highlights the potential of plasma catalysis in significantly improving CH4 conversion at lower temperatures and atmospheric pressure. [ABSTRACT FROM AUTHOR]

Herein, a heterogeneous structure of Ni–Mo catalyst comprising Ni4Mo nanoalloys decorated on a MoOx matrix via electrodeposition is introduced. This catalyst exhibits remarkable hydrogen evolution reaction (HER) activity across a range of pH conditions. The heterogeneous Ni–Mo catalyst showed low overpotentials only of 24 and 86, 21 and 60, and 37 and 168 mV to produce a current density of 10 and 100 mA cm−2 (η10 and η100) in alkaline, acidic, and neutral media, respectively, which represents one of the most active catalysts for the HER. The enhanced activity is attributed to the hydrogen spillover effect, where hydrogen atoms migrate between the Ni4Mo alloys and the MoOx matrix, forming hydrogen molybdenum bronze as additional active sites. Additionally, the Ni4Mo facilitated the water dissociation process, which helps the Volmer step in the alkaline/neutral HER. Through electrochemical analysis, in situ Raman spectroscopy, and density functional theory calculations, the fast HER mechanism is elucidated. [ABSTRACT FROM AUTHOR]

This work investigates the influence of minute additions of cobalt (Co) on the hydrogen absorption characteristics, phase composition, binding energy, and adsorption energy of the Zr70V24.6Fe5.4−xCox (wt%) (x = 0 ~ 2.0) alloys. The research revealed that the Zr70V24.6Fe4.4Co1.0 alloy exhibits the peak hydrogen absorption capacity. In comparison with the Zr70V24.6Fe5.4 (wt%) alloy, the hydrogen absorption properties increase from 80196.34 Pa cm3 g−1 (x = 0) to 133364.79 Pa cm3 g−1 (x = 1.0 wt%), representing a 66.30% improvement in performance. The enhancements in performance can be attributed to: an increase in lattice volume due to the addition of Co, which promotes the diffusion of hydrogen atoms within the lattice; a phase transition of the AB2 phase from Zr(V0.75Fe0.25)2 to Zr(V0.91Co0.09)2, and a significant decrease in the binding energy of Zr from 182.99 eV (x = 0) to 182.30 eV (x = 1.0 wt%), V in the alloy from 530.91 eV (x = 0) to 530.35 eV (x = 1.0 wt%), thereby enhancing the alloy's reactivity; according to the density functional theory calculations, the weighted adsorption energy of the alloy for H2 is increased from 35.11 to 38.14 eV. These research findings offer valuable guidance for the development of getters, and besides, expected to help promote further application of getters in high-tech fields such as military and medical. [ABSTRACT FROM AUTHOR]

We investigate the physical origins of the Balmer decrement anomalies in GS-NDG-9422 and RXCJ2248-ID galaxies at z ∼ 6 whose H α /H β values are significantly smaller than 2.7, the latter of which also shows anomalous H γ /H β and H δ /H β values beyond the errors. Because the anomalous Balmer decrements are not reproduced under the Case B recombination, we explore the nebulae with optical depths smaller and larger than the Case B recombination by physical modeling. We find two cases quantitatively explaining the anomalies: (1) density-bounded nebulae that are opaque only up to around Ly γ –Ly8 transitions and (2) ionization-bounded nebulae partly/fully surrounded by optically thick excited H i clouds. The case of (1) produces more H β photons via Ly γ absorption in the nebulae, requiring fine tuning in optical depth values, while this case helps ionizing photon escape for cosmic reionization. The case of (2) needs the optically thick excited H i clouds with N 2 ≃ 1012−1013 cm−2, where N 2 is the column density of the hydrogen atom with the principal quantum number of n = 2. Interestingly, the high N 2 values qualitatively agree with the recent claims for GS-NDG-9422 with the strong nebular continuum requiring a number of 2 s -state electrons and for RXCJ2248-ID with the dense ionized regions likely coexisting with the optically thick clouds. While the physical origin of the optically thick excited H i clouds is unclear, these results may suggest gas clouds with excessive collisional excitation caused by an amount of accretion and supernovae in the high- z galaxies. [ABSTRACT FROM AUTHOR]

Background: Esketamine, the first Food and Drug Administration-approved fastacting antidepressant, has limited use because of its addictive properties. Although the combination of dextromethorphan and bupropion partially addresses the limitations of esketamine, concerns remain regarding neurologic side effects related to dextromethorphan metabolites, and seizure risks associated with high-dose bupropion. SAL0114, a novel formulation combining deuterated dextromethorphan (in which hydrogen atoms are replaced with deuterium) with bupropion, seeks to enhance dextromethorphan stability through deuteration of its metabolic sites. This approach is expected to increase antidepressant efficacy, reduce metaboliteinduced safety issues, and allow for lower bupropion dosages. Methods: Radioligand competition binding assays were used to evaluate the impact of deuterium substitution on the in vitro activity of dextromethorphan and its metabolite, dextrorphan. In vitro hepatic microsomal stability and in vivo mouse pharmacokinetic assays were performed to assess the effects of deuteration on dextromethorphan stability. Two mouse models of behavioral despair were used to determine the antidepressant and synergistic effects of deuterated dextromethorphan and bupropion. Additionally, a reserpine-induced hypothermia rat model and an ammonia-induced cough mouse model were used to assess the in vivo effects from a pathological perspective. Results: Deuterated dextromethorphan maintained the same in vitro activity as dextromethorphan while exhibiting twice the metabolic stability both in vitro and in vivo. Combination with bupropion further improved its in vivo stability, increasing the exposure by 2.4 times. The combination demonstrated efficacy and synergistic effects in all tested animal models, showing superior efficacy compared with the dextromethorphan-bupropion combination. Conclusion: Deuteration improved dextromethorphan metabolic stability without altering its in vitro activity. Bupropion enhanced this stability and synergistically boosted the antidepressant effect by increasing deuterated dextromethorphan exposure in vivo. This enhanced metabolic stability suggests a reduction in dextromethorphan metabolites associated with clinical neurological side effects. Consequently, SAL0114 is hypothesized to offer improved efficacy and safety compared with the non-deuterated combination, potentially allowing for lower bupropion dosages. Further clinical studies are required to confirm these preclinical findings. [ABSTRACT FROM AUTHOR]

Activation and selective oxidation of inert C(sp3)–H bonds remain one of the most challenging tasks in current synthetic chemistry due to the inherent inertness of C(sp3)–H bonds. In this study, inspired by natural monooxygenases, we developed a coordination polymer with naphthalenediimide (NDI)-based ligands and binuclear iron nodes. The mixed-valence FeIIIFeII species and chlorine radicals (Cl•) are generated via ligand-to-metal charge transfer (LMCT) between FeIII and chlorine ions. These Cl• radicals abstract a hydrogen atom from the inert C(sp3)–H bond of alkanes via hydrogen atom transfer (HAT). In addition, NDI converts oxygen to 1O2 via energy transfer (EnT), which then coordinates to FeII, forming an FeIV = O intermediate for the selective oxidation of C(sp3)–H bonds. This synthetic platform, which combines photoinduced EnT, LMCT and HAT, provides a EnT-mediated parallel multiphoton excitation strategy with kinetic synergy effect for selective C(sp3)–H oxidation under mild conditions and a blueprint for designing coordination polymer-based photocatalysts for C(sp3)–H bond oxidation. Activation and selective oxidation of inert C(sp3)–H bonds remain one of the most challenging tasks in current synthetic chemistry. Here, the authors develop a coordination polymer with naphthalenediimide-based ligands and binuclear iron nodes for the oxidation of C(sp3)-H bonds. [ABSTRACT FROM AUTHOR]

A copper catalyzed aerobic formal addition of aliphatic C(sp3)−H bonds to alkenes via a phenyl radical mediated intermolecular HAT process is reported herein, in which the phenylhydrazine not only acts as a HAT reagent precursor, but also as a hydrogen atom donor. This reaction affords an alternative method for the direct formal addition of aliphatic C(sp3)−H bonds to alkenes utilizing air as the radical initiator without additional reductants at ambient temperature. A variety of alkanes and electron‐deficient alkenes are successfully incorporated, furnishing a series of aliphatic C(sp3)−H formal addition products in 20–93% yield. Preliminary mechanistic studies show that the 2‐tetrahydrofuranyl and phenyl radical are formed in this reaction. [ABSTRACT FROM AUTHOR]

Splitting the five and seven‐membered rings of azulene and embedding them separately into a conjugated backbone provides azulene‐like polycyclic aromatic hydrocarbons (PAHs), which are of great interest in quantum and material chemistry. However, the synthetic accessibility poses a significant challenge. In this study, we present the synthesis of a novel azulene‐like PAH, Pery‐57, which can be viewed as the integration of a perylene framework into the split azulene. The compact structure of Pery‐57 displays several intriguing characteristics, including NIR II absorption at 1200 nm, a substantial dipole moment of 3.5 D, and head‐to‐tail alternating columnar packing. Furthermore, Pery‐57 exhibits remarkable redox properties. The cationic radical Pery‐57⋅+ readily captures a hydrogen atom. Variable‐temperature NMR (VT NMR) and variable‐temperature EPR (VT‐EPR) studies reveal that the dianion Pery‐572− possesses an open‐shell singlet ground state and demonstrates significant global anti‐aromaticity. The dication Pery‐572+ is also predicted to exhibit diradical character. Despite bearing three bulky substituents, Pery‐57 displays p‐type transport characteristics with a mobility of 0.03 cm2 V−1 s−1, attributed to its unique azulene‐like structure. Overall, this work directs interest in azulene‐like PAHs, a unique member of nonalternant PAHs showcasing exceptional properties and applications. [ABSTRACT FROM AUTHOR]

Hydrogen atom abstraction is an important elementary chemical process but is very difficult to carry out enantioselectively. We have developed catalysts, readily derived from the Cinchona alkaloid family of natural products, which can achieve this by virtue of their chiral amine structure. The catalyst, following single-electron oxidation, desymmetrizes meso-diols by selectively abstracting a hydrogen atom from one carbon center, which then regains a hydrogen atom by abstraction from a thiol. This results in an enantioselective epimerization process, forming the chiral diastereomer with high enantiomeric excess. Cyclic and acyclic 1,2-diols are compatible, as are acyclic 1,3-diols. Additionally, we demonstrate the viability of combining our approach with carbon-carbon bond formation in Giese addition. Given the increasing number of synthetic methods involving hydrogen atom transfer steps, we anticipate that this work will have a broad impact in the field of enantioselective radical chemistry. [ABSTRACT FROM AUTHOR]

The search for water on Mars has long been a theme of intense exploration, as it represents a means of addressing Mars' current climate as well as its evolution in the recent and more distant past. Since the 1970s, several missions have carried instruments to track water in the atmosphere, leading to the conceptualization of a water cycle on Mars characterized by intense seasonal variability in water vapor abundance across the planet. After Mariner 9, Viking, Phobos 2 and Mars Global Surveyor, Mars Express has become the fifth orbiter capable of detecting water vapour, with unique features: measurements by several instruments, each probing a distinct wavelength region from near-infrared to thermal infrared, altitude-dependent profiling of water thanks to solar occultation, and observation in the exosphere of its by-product, hydrogen atoms, which can escape into space, depriving Mars of its primordial water reservoir. Thanks to Mars Express, a new vision of Mars' water cycle and escape processes has emerged. The achievements of Mars Express, as well as the legacy of other missions, which established the foundations of our understanding of Mars' water cycle are presented in this article. [ABSTRACT FROM AUTHOR]

In this article, we have investigated the electronic structure of Co2Si monolayer by first-principle calculations, and the phonon spectrum calculation results do not show any imaginary frequencies, indicating its stable existence. The calculation of electronic structure shows that there are two nodal loops centered on gamma in the Kz=0 plane, and these two nodal loops still exist considering the coupling of spin and orbitals. The calculation results of free energy indicate that Co2Si monolayer is very suitable as a catalyst for hydrogen evolution reactions. Its Gibbs free energy for adsorbing hydrogen atom is as low as -0.067 eV, which is superior to many other catalytic materials and comparable to Pt. In addition, when electron or hole doping is carried out, its Gibbs free energy for hydrogen absorption changes accordingly. These results indicate that Co2Si monolayer has the potential to become a high-performance and inexpensive catalyst for hydrogen evolution reactions. [ABSTRACT FROM AUTHOR]

PHOTH-graphene is a newly predicted 2D carbon material with a low-energy structure. However, its mechanical stability and fracture properties are still elusive. The mechanical stability, elastic, and fracture properties of PHOTH-graphene were investigated using classical molecular dynamics (MD) simulations equipped with REBO potential in this study. The influence of orientation and temperature on mechanical properties was evaluated. Specifically, the Young's modulus, toughness, and ultimate stress and strain varied by −26.14%, 36.46%, 29.04%, and 25.12%, respectively, when comparing the armchair direction to the zigzag direction. The percentage reduction in ultimate stress, ultimate strain, and toughness of the material in both directions after a temperature increase of 1000 K (from 200 K to 1200 K) ranged from 56.69% to 91.80%, and the Young's modulus was reduced by 13.63% and 7.25% in both directions, respectively, with Young's modulus showing lower sensitivity. Defects usually weaken the material's strength, but adding random point defects in the range of 3% to 5% significantly increases the ultimate strain of the material. Furthermore, hydrogen atom adsorption induces crack expansion to occur earlier, and the crack tip without hydrogen atom adsorption just began to expand when the strain was 0.135, while the crack tip with hydrogen atom adsorption had already undergone significant expansion. This study provides a reference for the possible future practical application of PHOTH-graphene in terms of mechanical properties and fracture failure. [ABSTRACT FROM AUTHOR]

Recent studies of TWINS Lyman-α observations have reported an increase in geocoronal column brightness during geomagnetic storms, indicating enhanced exospheric hydrogen atom density (NH). This suggests a complex role of exospheric neutrals in determining storm-time magnetosphere dynamics and their energy release through charge-exchange processes. We developed a Model for Analyzing Terrestrial Exosphere (MATE) to investigate storm-time exospheric behaviors and their physical drivers. MATE traces test hydrogen atoms backward in time from locations in the exosphere to a nominal exobase altitude of 500 km, employing Newtonian mechanics with gravitational force. The model then calculates the phase-space densities (PSDs) of test hydrogen atoms at the exobase using the Maxwellian distribution with physics-based exobase conditions from the TIMEGCM upper atmosphere model. MATE maps PSDs at the exobase to the exosphere using Liouville's Theorem under collisionless assumptions and derives N[sub H] by integrating the PSDs across velocity space. We conducted MATE simulation before, during, and after a minor geomagnetic storm from 12 to 18 June 2008, and compared the model results with N[sub H] estimates from the TWINS geocorona data. MATE reproduces storm-time density enhancements soon after the minimum Dst is reached, matching well with a general trend of TWINS N[sub H] estimates. The results suggest that upper atmospheric heating during a geomagnetic storm increases the number of ballistic and escaping hydrogen atoms entering the exosphere from the exobase, thereby boosting NH. However, the magnitude of modeled N[sub H] mismatches the TWINS N[sub H] estimates. The potential mechanisms of this density discrepancy include the physics excluded in the MATE model -- such as neutral-neutral collisions, neutral-plasma charge exchange, solar radiation pressure, and photoionization -- as well as the higher exobase hydrogen density of TIMEGCM compared to typical empirical values, which will be addressed in future. [ABSTRACT FROM AUTHOR]

Ethanolamine hydrates containing from one to seven water molecules were identified via rotational spectroscopy with the aid of accurate quantum chemical methods considering anharmonic vibrational corrections. Ethanolamine undergoes significant conformational changes upon hydration to form energetically favorable hydrogen bond networks. The final structures strongly resemble the pure (H2O)3–9 complexes reported before when replacing two water molecules by ethanolamine. The 14N nuclear quadrupole coupling constants of all the ethanolamine hydrates have been determined and show a remarkable correlation with the strength of hydrogen bonds involving the amino group. After addition of the seventh water molecule, both hydrogen atoms of the amino group actively contribute to hydrogen bond formation, reinforcing the network and introducing approximately 21–27 % ionicity towards the formation of protonated amine. These findings highlight the critical role of microhydration in altering the electronic environment of ethanolamine, enhancing our understanding of amine hydration dynamics. [ABSTRACT FROM AUTHOR]

Platinum (Pt) metal is widely acknowledged as a highly efficient electrocatalyst for hydrogen evolution reaction (HER) in acidic electrolyte. However, its performance in alkaline environments is significantly lower owing to the sluggish water dissociation step. Herein, we synthesized an ultrahigh Pt-mass-activity alkaline HER catalyst using microwave reduction method in air. Our catalyst, PtRu@CNT, comprises PtRu alloy nanoparticles uniformly loaded on carbon nanotubes, with Pt and Ru contents of 12.3 wt% and 4.5 wt%, respectively. The PtRu alloy nanoparticles have an average diameter of about 3 nm and a face-centered cubic structure, and the introduction of Ru has led to a modified electronic structure in Pt. As a result, an impressively low HER overpotential of 13 mV was achieved, significantly lower than commercial 20 wt% Pt/C (61 mV). PtRu@CNT exhibited a high turnover frequency based on metal mass of 3.06 s−1 at 100 mV, about 6 times higher than commercial Pt/C (0.46 s−1 at 100 mV), highlighting its excellent intrinsic activity. The HER mechanism of PtRu@CNT is a Volmer-Tafel mechanism, where the rate-limiting step changed to the recombination of hydrogen atoms from initial water dissociation, attributed to the presence of Ru. The alkaline HER activity of PtRu@CNT ranks among the best of currently reported Pt-based catalysts. [ABSTRACT FROM AUTHOR]

In this study, we investigate the protonation effects on the structure, relative stability and basicity of complexes formed by the interaction of monomers and dimers of BeX2 and MgX2 (X = H, F) with NH3, CH2NH, HCN, and NC5H5 bases. Calculations were performed using the M06‐2X/aug‐cc‐pVTZ formalism, along with QTAIM, ELF and NCI methods for electron density analysis and MBIE and LMO‐EDA energy decomposition analyses for interaction enthalpies. The protonation of the MH2– and M2H4–Base complexes occurs at the negatively charged hydrogen atoms of the MH2 and M2H4 moieties through typical hydride abstraction reactions, while protonation at the N atom of the base is systematically less exothermic. The preference for the hydride transfer mechanism is directly associated with the significant exothermicity of H2 formation through the interaction between H− and H+, and the high hydride donor ability of these complexes. The basicity of both, MH2 and M2H4 compounds increases enormously upon association with the corresponding bases, with the increase exceeding 40 orders of magnitude in terms of ionization constants. Due to the smaller exothermicity of HF formation, the basicity of fluorides is lower than that of hydrides. In Be complexes, the protonation at the N atom of the base dominates over the fluoride abstraction mechanism. However, for the Mg complexes the fluoride abstraction mechanism is energetically the most favorable process, reflecting the greater facility of Mg complexes to lose F−. [ABSTRACT FROM AUTHOR]

Hydrogen segregation behaviors at BCC-Fe Σ3 (111) grain boundary (GB) as well as the effects of alloying solutes were studied by the first-principles method. The segregation energy of alloying solutes at different periods presents a concave-down parabolic-like relationship with the atomic number, and the 4 d transition alloying solutes show a higher averaged segregation tendency. At the favorable trapping site, hydrogen segregation energy decreased by increasing the number of hydrogen atoms up to 0.85/Å2 in the plane vertical to the GB. Mo, Tc, Ru, Ta, W, Re, Os, and Ir strengthen GB and inhibit hydrogen segregation. Significantly, the interaction between alloying solutes and hydrogen segregation was elucidated by emphasizing the separation of the chemical and the mechanical contributions, and appropriate descriptors on hydrogen segregation energy influenced by alloying solutes were screened. This work offers theoretical backing to comprehend hydrogen segregation behaviors and the effects of alloying solutes to design advanced high-strength steels resistant to hydrogen embrittlement. • Hydrogen segregation behaviors at pure BCC Σ3 (111) grain boundary were studied. • Alloy solute segregation behaviors at pure BCC Σ3 (111) grain boundary were studied. • Interaction between alloying solutes and hydrogen at grain boundary was elucidated. • Descriptors on hydrogen segregation energy at grain boundary were screened. • Relationship between hydrogen segregation at grain boundary and HE was discussed. [ABSTRACT FROM AUTHOR]

Hydrogen, the lightest and most abundant element in the universe, plays essential roles in a variety of clean energy technologies and industrial processes. For over a century, it has been known that hydrogen can significantly degrade the mechanical properties of materials, leading to issues like hydrogen embrittlement. A major challenge that has significantly limited scientific advances in this field is that light atoms like hydrogen are difficult to image, even with state-of-the-art microscopic techniques. To address this challenge, here, we introduce Atom-H, a versatile and generalizable machine learning-based framework for imaging hydrogen atoms at the atomic scale. Using a high-resolution electron microscope image as input, Atom-H accurately captures the distribution of hydrogen atoms and local stresses at lattice defects, including dislocations, grain boundaries, cracks, and phase boundaries. This provides atomic-scale insights into hydrogen-governed mechanical behaviors in metallic materials, including pure metals like Ni, Fe, Ti and alloys like FeCr. The proposed framework has an immediate impact on current research into hydrogen embrittlement and is expected to have far-reaching implications for mapping "invisible" atoms in other scientific disciplines. [ABSTRACT FROM AUTHOR]

Single atom alloy (SAA) clusters formed by anchoring single atoms in small supported host clusters are emerging as catalysts with high performance. In this work, density functional theory (DFT) calculations and ab‐initio molecular dynamics (AIMD) simulations are performed to study the stability and the structure evolution of γ‐alumina‐supported platinum/copper SAA clusters of sub‐nanometer size in hydrogen environment. Due to the strong dynamic nature of both Cu cluster and anchored Pt single atom and their evolving interaction with the support, different isomers with different geometric and energetic properties are predicted. Extensive sampling through AIMD simulations reveals strong effect of hydrogen on the location of Pt single atom and strong variation of the cluster shape, evolving from 3D to concave and planar shapes wetting the alumina support. Interfacial site location of Pt single atom is found to be hydrogen coverage dependent. When the hydrogen coverage increases, the Pt single atom located preferentially at the interfacial site is pulled up by hydrogen atoms toward the upper surface Cu layers. The interaction of Pt/Cu cluster with alumina is predicted to decrease with increasing hydrogen coverage. Finally, electronic structure analysis reveals dramatic effect of hydrogen on the metallic nature of the catalysts. [ABSTRACT FROM AUTHOR]

Non‐centrosymmetric organics are promising nonlinear optical (NLO) candidates, which always exhibit a short UV absorption cutoff edge, and a strong second harmonic generation (SHG) response, but an overlarge birefringence. Here, in order to optimize the birefringence, the methyl modulation of π‐conjugated organic planar units is proposed and implemented with the urea structure as a template. Thus, N‐methylurea and N,N'‐dimethylurea crystals are obtained by partially replacing hydrogen atoms with methyl groups. This replacement reduces hydrogen donors and weakens interchain hydrogen bonds, which facilitates the decreasing density and the parallel arrangement of π‐conjugated planar units. Hence, both N‐methylurea and N,N'‐dimethylurea crystals exhibit not only an optimized birefringence (N‐methylurea ≈0.099 and N,N'‐dimethylurea ≈0.072 at 546 nm) but also an enhanced SHG response (N‐methylurea ≈1.2 × β‐BaB2O4 and N,N'‐dimethylurea ≈1.9 × β‐BaB2O4), while maintaining a short UV absorption cutoff edge. Therefore, this work provides a novel strategy for the structural design and performance modulation of organic NLO crystals. [ABSTRACT FROM AUTHOR]

The hydrogen embrittlement (HE) susceptibility of the X52 pipeline steels in simulated hydrogen-blended natural gas (HBNG) environments were investigated with a combination of in situ high-pressure gaseous hydrogen permeation tests, slow strain rate tensile (SSRT) tests and molecular dynamics simulation, the results were compared with the X80 steel. The HE susceptibility of the X52 steel was found higher than that of the X80 steel. The mechanism of the two steels showing different HE susceptibility was analyzed from a point of permeation parameters and molecular dynamics simulation. The results showed that the X52 steel contained more impurity elements and a larger grain size, leading to a higher hydrogen solubility and a microstructure with lower HE resistance. This study suggests that the steel microstructure and the hydrogen permeation property are crucial for the understanding and prediction of the HE susceptibility of the steels. • N 2 partial pressure would not influence the hydrogen permeation behaviour. • HE susceptibility is not necessarily positively correlated with steel grade. • Phase transition/dislocation emission is main deformation mechanism of boundaries. • Hydrogen atom inhibit local energy release and promote crack initiation. • Finer grain weakens the inhibition of local energy release caused by H. [ABSTRACT FROM AUTHOR]

A rare example of the palladium–catalyzed sp3 C−H bond activation in a monoterpene‐based compound has been observed in the reaction of PdCl2 with a (+)‐3‐carene‐based ligand HL (HL=N‐((1aS,3S,7bR)‐1,1,3‐trimethyl‐7‐phenyl‐5‐(pyridin‐2‐yl)‐1a,2,3,7b‐tetrahydro‐1H‐cyclopropa[f]quinolin‐3‐yl)acetamide), which yielded the [PdLCl] complex. In contrast to the vast majority of C(sp3)−H activation reactions which require prolonged heating and mixing due to the inert character of the corresponding bond, the reaction reported herein proceeds rapidly under mild conditions. A theoretical insight into the ligand deprotonation has been performed by DFT calculations. The mechanism of the C−H activation involves (i) simultaneous coordination of the CH3 group of HL to the Pd2+ ion and decoordination of the Cl− anion with consequent formation of a Cl⋅⋅⋅H−N hydrogen bond with the amide group, (ii) approximation of the out‐of‐sphere Cl− anion to one of the hydrogen atoms of the CH3 group mediated by the crane motion of the amide group and (iii) the ejection of the HCl molecule, which increases the entropy of the system and serves as a driving force for the reaction. [ABSTRACT FROM AUTHOR]

In this paper, the laser pulse evolution arising from the field ionization during the interaction of a long laser pulse with gaseous hydrogen atoms is investigated using the kinetic 1D‐3 V Particle‐In‐Cell (PIC) Smilei simulation code. After performing various simulations, it is shown that the field ionization of hydrogen atoms has a non‐negligible effect on the evolution of the laser pulse compared to the pre‐ionized plasma case. The results of our simulations show that the amount of these evolutions is strongly dependent on the parameters of the laser and initial ionization assumed. In this regard, two main mechanisms are responsible for the changes in the generated radiations and then the evolution of the laser pulse. When the average degree of ionization is weak, the backscattered Raman radiations can provide the necessary conditions for the chaotic behavior to occur and the laser pulse to evolve. When the laser and plasma pulse parameters (such as the laser pulse amplitude, hydrogen atoms density, and the rise time of pulse) are selected so that a strong space charge field is formed, the wave breaking (which happened faster due to density changes during the field ionization) is the main factor for evolutions in the laser pulse. [ABSTRACT FROM AUTHOR]

AbstractThe vibrations were attributed to 5-chloro-2-mercaptobenzimidazole using FTIR and FT-Raman spectroscopy. The optimized geometrical parameters, IR intensity, and the Raman activity of the vibrational bands were estimated using the Becke three-parameter Lee-Yang-Parr functional and the 6-311++G(d,p) level of theory. These findings are compared with the experimental data. The molecule’s HOMO-LUMO energy gap is found to be 4.418 eV. UV-Vis analysis reveals that the π→π* transition, which happens when electron density shifts from nitrogen, sulfur, and chlorine atoms in the molecule, to the electrons of the C-C bonds of the ring. Total density of states was used to assess the molecular orbital contributions. There are 47α and 47β electrons totaling 94 electrons in the DOS spectrum. NBO investigations indicate that a considerable stabilizing energy of 30.37 and 30.90 Kcal/mol was revealed by the lone pair transition of N1 and N3 atoms to π*(C7-C8) and π*(C4-C9). The more electrophilic region, as seen by the red zone in MEP mapping, lies in the vicinity of the nitrogen and sulfur atoms. The molecule’s hydrogen atoms are found in the blue nucleophilic area. The theoretical chemical shifts for 1H and 13C NMR ranged from 7.03 to 8.23 ppm and 113.10 to 207.31 ppm, respectively. The docking research showed that the molecule attached to protein 1AQU with a greater binding energy of −6.8 Kcalmol−1. The cytotoxicity of the sample was evaluated against a MCF-7 cell line (IC50 = 16.54 µg/ml) and exhibited a good breast cancer action. In addition, ADMET prediction has been used to estimate the medicinal applicability of the chemical. [ABSTRACT FROM AUTHOR]

Bimetallic single‐atom‐dimer (SAD) with unique electronic structures and adsorption properties presents exceptional catalytic performance owing to atomic‐level synergistic effects from direct bonding between different metal atoms. However, inherent characteristics of substrate present great challenges in their synthesis and mechanism investigation. Herein, a unique phosphorus modified atomic layer deposition (P‐ALD) strategy is designed to synthesize P‐anchored Pt–W dimers, overcoming substrate limitation (Pt1W1–P/C). Motivated introduction of atomic P site via ALD can effectively anchor one‐to‐one AB bimetallic dimer structure on various substrates, confirmed by X‐ray absorption spectroscopy (XAS). Density functional theory reveals an interatomic synergistic adsorption mechanism, with W as primary hydrogen adsorption site extending to Pt, optimizing hydrogen coverage, leading to 60‐fold increase in mass activity compared to commercial Pt/C in both acidic and alkaline electrolytes. Anion exchange membrane water electrolyzer with ultra‐low loading Pt1W1–P/C (50 µgPt cm−2) catalyst operates durability at 1000 mA cm−2 for 550 h with ultra‐low degradation of 38 µV h−1. Operando XAS confirms hydrogen adsorption pathway between atoms and remarkable self‐healing ability of P–Pt–W–O sites under all‐pH conditions. These findings extend the application domain of SAD to catalytic manufacturing methods and aid in designing advanced materials with multi‐atomic active sites. [ABSTRACT FROM AUTHOR]