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We describe a method to compute photon–matter interaction and atomic dynamics with x-ray lasers using a hybrid code based on classical molecular dynamics and collisional-radiative calculations. The forces between the atoms are dynamically determined based on changes to their electronic occupations and the formation of a free electron cloud created from the irradiation of photons in the x-ray spectrum. The rapid transition from neutral solid matter to dense plasma phase allows the use of screened potentials, reducing the number of non-bonded interactions. In combination with parallelization through domain decomposition, the hybrid code handles large-scale molecular dynamics and ionization. This method is applicable for large enough samples (solids, liquids, proteins, viruses, atomic clusters, and crystals) that, when exposed to an x-ray laser pulse, turn into a plasma in the first few femtoseconds of the interaction. We present four examples demonstrating the applicability of the method. We investigate the non-thermal heating and scattering of bulk water and damage-induced dynamics of a protein crystal using an x-ray pump–probe scheme. In both cases, we compare to the experimental data. For single particle imaging, we simulate the ultrafast dynamics of a methane cluster exposed to a femtosecond x-ray laser. In the context of coherent diffractive imaging, we study the fragmentation as given by an x-ray pump–probe setup to understand the evolution of radiation damage in the time range of hundreds of femtoseconds. [ABSTRACT FROM AUTHOR]

As the most important solvent, water has been at the center of interest since the advent of computer simulations. While early molecular dynamics and Monte Carlo simulations had to make use of simple model potentials to describe the atomic interactions, accurate ab initio molecular dynamics simulations relying on the first-principles calculation of the energies and forces have opened the way to predictive simulations of aqueous systems. Still, these simulations are very demanding, which prevents the study of complex systems and their properties. Modern machine learning potentials (MLPs) have now reached a mature state, allowing us to overcome these limitations by combining the high accuracy of electronic structure calculations with the efficiency of empirical force fields. In this Perspective, we give a concise overview about the progress made in the simulation of water and aqueous systems employing MLPs, starting from early work on free molecules and clusters via bulk liquid water to electrolyte solutions and solid–liquid interfaces. [ABSTRACT FROM AUTHOR]

The quantum Drude oscillator (QDO) model has been widely used as an efficient surrogate to describe the electric response properties of matter as well as long-range interactions in molecules and materials. Most commonly, QDOs are coupled within the dipole approximation so that the Hamiltonian can be exactly diagonalized, which forms the basis for the many-body dispersion method [Phys. Rev. Lett. 108, 236402 (2012)]. The dipole coupling is efficient and allows us to study non-covalent many-body effects in systems with thousands of atoms. However, there are two limitations: (i) the need to regularize the interaction at short distances with empirical damping functions and (ii) the lack of multipolar effects in the coupling potential. In this work, we convincingly address both limitations of the dipole-coupled QDO model by presenting a numerically exact solution of the Coulomb-coupled QDO model by means of quantum Monte Carlo methods. We calculate the potential-energy surfaces of homogeneous QDO dimers, analyzing their properties as a function of the three tunable parameters: frequency, reduced mass, and charge. We study the coupled-QDO model behavior at short distances and show how to parameterize this model to enable an effective description of chemical bonds, such as the covalent bond in the H2 molecule. [ABSTRACT FROM AUTHOR]

In this work, we propose a linear machine learning force matching approach that can directly extract pair atomic interactions from ab initio calculations in amorphous structures. The local feature representation is specifically chosen to make the linear weights a force field as a force/potential function of the atom pair distance. Consequently, this set of functions is the closest representation of the ab initio forces, given the two-body approximation and finite scanning in the configurational space. We validate this approach in amorphous silica. Potentials in the new force field (consisting of tabulated Si–Si, Si–O, and O–O potentials) are significantly different than existing potentials that are commonly used for silica, even though all of them produce the tetrahedral network structure and roughly similar glass properties. This suggests that the commonly used classical force fields do not offer fundamentally accurate representations of the atomic interaction in silica. The new force field furthermore produces a lower glass transition temperature (Tg ∼ 1800 K) and a positive liquid thermal expansion coefficient, suggesting the extraordinarily high Tg and negative liquid thermal expansion of simulated silica could be artifacts of previously developed classical potentials. Overall, the proposed approach provides a fundamental yet intuitive way to evaluate two-body potentials against ab initio calculations, thereby offering an efficient way to guide the development of classical force fields. [ABSTRACT FROM AUTHOR]

This study reveals the impact resistance of shear thickening gel (STG) impregnated four‐layer regular angle interlocking fabrics (AIF) composites. The effects of STG parameters, including reaction time, reaction temperature, and reaction ratio, on the rheological characterization and mechanical properties of STG/AIF flexible composites were investigated. The results show that the increase in STG parameters accelerated the formation of BO crosslink bonds within the STG. The energy storage modulus of STG increased by three orders of magnitude for a reaction temperature of 230°C, a reaction time of 9 h, and a reaction ratio of 12.5%. STG had an obvious shear thickening effect. The coupling effect of STG and AIF increases the inter‐yarn friction. The shear thickening effect of STG and the deformation of AIF fabric synergistically absorbed the impact energy, and the energy absorption rate reached 95.6%. The material surface was not significantly damaged after the low‐velocity impact. The STG/AIF flexible composites showed excellent impact energy absorption properties. Highlights: A new high‐energy absorption and impact resistance composite was prepared.Increased STG reaction ratio and temperature promoted its internal reaction.B and O atomic interactions enhance the rheological properties of STG.STG and fabric synergistically improve the impact resistance. [ABSTRACT FROM AUTHOR]

Nonlinear feedback between the gauge field and the material field can yield novel quantum phenomena. Here, the interplay between a density-dependent artificial gauge field and Bose–Einstein condensates (BECs) trapped in an optical lattice is studied. The energy spectrum and superfluidity represented by energetic and dynamical stabilities of the system are systematically discussed. A density-dependent artificial gauge field with a back-action between the BECs dynamics and the gauge field induces an effective atomic interaction that depends on the quasi-momentum and density of the condensates, resulting in a symmetry-broken energy spectrum and exotic stability phase diagram, that is, the system is only stable in a certain range of atoms density and under a limited lattice strength. The density-dependent artificial gauge field changes the sequence for the emergence of energetic and dynamical instability and the regimes of the energetic and dynamical instabilities are significantly separated, offering an efficient way to examine the energetic and dynamical instabilities of superfluids separately. In particular, the density-dependent artificial gauge field, as a mechanism for transferring momentum to the fluid, results in dynamic instability of the condensates even in free space. Our results provide deep insights into the dynamical response of superfluid systems to gauge fields and have potential applications for the coherent control of exotic superfluid states. [ABSTRACT FROM AUTHOR]

Full landscapes of atomic interactions, including strong chemical bonds, intramolecular noncovalent and intermolecular, were calculated for a series of six highly polymorphic compounds, all of which exhibit pronounced biological activity: sulfapyridine, sulfamerazine, sulfamethoxazole, sulfathiazole, chlorpropamide and tolbutamide. To ensure strict and unambiguous characterization of atomic bonding, the method of molecular Voronoi–Dirichlet polyhedra (MVDP) was employed. Conformational differences among molecules within polymorphic families were quantified in terms of the peculiarities of the intramolecular noncovalent interactions being realized. On the basis of the k–Φ criterion all the studied molecules were proved to show unique systems of intramolecular noncovalent interactions thus being unique conformers. The relative importance of intramolecular noncovalent interactions, which have the maximum effect on the conformation of the respective molecules, was assessed. Good correlation was observed between the characteristics of π stacking calculated using the MVDP method and experimental polymorphic transition temperatures of sulfamethoxazole. The ratio of crystal volume with respect to strong chemical bonds, intramolecular noncovalent and intermolecular interactions for a large amount of unrelated compounds was analyzed. [ABSTRACT FROM AUTHOR]

Many of the most exciting materials discoveries in fundamental condensed matter physics are made in systems hosting some degree of intrinsic disorder. While disorder has historically been regarded as something to be avoided in materials design, it is often of central importance to correlated and quantum materials. This is largely driven by the conceptual and theoretical ease to handle, predict, and understand highly uniform systems that exhibit complex interactions, symmetries, and band structures. In this Perspective, we highlight how flipping this paradigm has enabled exciting possibilities in the emerging field of high entropy materials, focusing primarily on high entropy oxide and chalcogenide quantum materials. These materials host high levels of cation or anion compositional disorder while maintaining unexpectedly uniform single crystal lattices. The diversity of atomic scale interactions of spin, charge, orbital, and lattice degrees of freedom are found to emerge into coherent properties on much larger length scales. Thus, altering the variance and magnitudes of the atomic scale properties through elemental selection can open new routes to tune global correlated phases, such as magnetism, metal–insulator transitions, ferroelectricity, and even emergent topological responses. The strategy of embracing disorder in this way provides a much broader pallet from which functional states can be designed for next-generation microelectronic and quantum information systems. [ABSTRACT FROM AUTHOR]

Cryptophycins are microtubule-targeting agents (MTAs) that belong to the most potent antimitotic compounds known to date; however, their exact molecular mechanism of action remains unclear. Here, we present the 2.2 Å resolution X-ray crystal structure of a potent cryptophycin derivative bound to the αβ-tubulin heterodimer. The structure addresses conformational issues present in a previous 3.3 Å resolution cryoelectron microscopy structure of cryptophycin-52 bound to the maytansine site of β-tubulin. It further provides atomic details on interactions of cryptophycins, which had not been described previously, including ones that are in line with structure-activity relationship studies. Interestingly, we discovered a second cryptophycin-binding site that involves the T5-loop of β-tubulin, a critical secondary structure element involved in the exchange of the guanosine nucleotide and in the formation of longitudinal tubulin contacts in microtubules. Cryptophycins are the first natural ligands found to bind to this new "βT5-loop site” that bridges the maytansine and vinca sites. Our results offer unique avenues to rationally design novel MTAs with the capacity to modulate T5-loop dynamics and to simultaneously engage multiple β-tubulin binding sites. [ABSTRACT FROM AUTHOR]

Context: Previous studies have proposed that the backbone of metallic glasses consists mainly of high-centrosymmetric structures, particularly Z clusters, which are responsible for the strength of the glass matrix. However, exploring these networks involves medium-range order analysis, a topic still not fully understood in the literature. This study investigates the atomic connectivity of CuZr metallic glasses by analyzing Z clusters using complex networks to establish their relationship with the mechanical behavior. Our results reveal higher connectivity and larger network sizes in the sample exhibiting the most pronounced stress overshoot, while the opposite trend is observed in samples with less pronounced stress overshoot. Metrics, such as density and clustering coefficient, further validate the correlation between Z cluster connectivity and mechanical behavior. These findings underscore the critical role of Z cluster connectivity in understanding the mechanical response of metallic glasses. Methods: Molecular dynamics simulations were conducted using the LAMMPS software. Atomic interactions in Cu 50 Zr 50 metallic glasses were modeled using the embedded atom method, and compression tests were performed to assess the mechanical response. Atomic connectivity was examined through complex network analysis based on Z clusters, utilizing the NetworkX library for the Python programming language. Within this framework, parameters such as the average coordination number, network size, and network density were calculated, revealing the relationship between the interpenetrating Z cluster structure and the mechanical response of the samples. [ABSTRACT FROM AUTHOR]

AgCrO 2 nanoparticles incorporated with magnesium were synthesized by a hydrothermal method and its response to ethylene glycol vapor was improved, with a remarkable detection limited down to ppm level. This hybrid oxide also exhibits a high selectivity and response (16.2–10 ppm ethylene glycol) at low operation temperature of 120 °C with short response/recovery time (32s/130s). Based on the microstructural characterizations including X-ray diffraction, electron microscope observation and X-ray photoelectron spectroscope probing, the first-principles calculation of the gas-oxide system was performed to elucidate the sensing enhancement by Mg hybridization. It started with the adsorption of gas to the superficial Ag atom in the vicinity of doped Mg, which was then followed by dehydrogenation resulting in electrons releasing and charge transfer through the adatom bond and supplementary route towards a terminal Ag atom. This work provided a new perspective to the atomic interaction between the specific gas molecules and sensitive oxide layer, which delivered approaches of chemiresistive material system optimization for advanced gas sensing application. [ABSTRACT FROM AUTHOR]

To facilitate the transition of quantum effects from the controlled laboratory environment to practical real-world applications, there is a pressing need for scalable platforms. One promising strategy involves integrating thermal vapors with nanostructures designed to manipulate atomic interactions. In this tutorial, we aim to gain deeper insights into this by examining the behavior of thermal vapors that are confined within nanocavities or waveguides and exposed to near-resonant light. We explore the interactions between atoms in confined dense thermal vapors. Our investigation reveals deviations from the predictions of continuous electrodynamics models, including density-dependent line shifts and broadening effects. In particular, our results demonstrate that by carefully controlling the saturation of single atoms and the interactions among multiple atoms using nanostructures, along with controlling the geometry of the atomic cloud, it becomes possible to manipulate the effective optical nonlinearity of the entire atomic ensemble. This capability renders the hybrid thermal atom-nanophotonic platform a distinctive and valuable one for manipulating the collective effect and achieving substantial optical nonlinearities. [ABSTRACT FROM AUTHOR]

The sensitivity of atom interferometers depends on their ability to realize long pulse separation times and prevent loss of contrast by limiting the expansion of the atomic ensemble within the interferometer beam through matter-wave collimation. Here we investigate the impact of atomic interactions on collimation by applying a lensing protocol to a 39K Bose-Einstein condensate at different scattering lengths. Tailoring interactions, we measure energies corresponding to (340 ± 12) pK in one direction. Our results are supported by an accurate simulation, which allows us to extrapolate a 2D ballistic expansion energy of (438 ± 77) pK. Based on our findings we propose an advanced scenario, which enables 3D expansion energies below 16 pK by implementing an additional pulsed delta-kick. Our results pave the way to realize ensembles with more than 1 × 105 atoms and 3D energies in the two-digit pK range in typical dipole trap setups without the need for micro-gravity or long baseline environments. Precision measurements with atom interferometers benefit from reducing the expansion rate of the atomic ensemble within the interferometric beam through matter-wave collimation. Here we demonstrate a collimation method based on time-averaged optical potentials and tunable interactions, realizing expansion energies of a few hundred picokelvin. [ABSTRACT FROM AUTHOR]

This study employs a combined computational and experimental approach to elucidate the mechanisms governing the interaction between lignin and urea, impacting lignin dissolution and subsequent aggregation behavior. Molecular dynamics (MD) simulations reveal how the urea concentration and temperature influence lignin conformation and interactions. Higher urea concentrations and temperatures promote lignin dispersion by disrupting intramolecular interactions and enhancing solvation. Density functional theory (DFT) calculations quantitatively assess the interaction energy between lignin and urea, supporting the findings from MD simulations. Anti-solvent precipitation demonstrates that increasing the urea concentration hinders the self-assembly of lignin nanoclusters. The findings provide valuable insights for optimizing lignin biorefinery processes by tailoring the urea concentration and temperature for efficient extraction and dispersion. Understanding the influence of urea on lignin behavior opens up avenues for designing novel lignin-based materials with tailored properties. This study highlights the potential for the synergetic application of MD simulations and DFT calculations to unravel complex material interactions at the atomic level. [ABSTRACT FROM AUTHOR]

Diabetes is a degenerative disease caused by either the body's inability to use insulin adequately or the pancreas's failure to release enough insulin. Diabetes is a glucose metabolic imbalance produced by the phosphodiesterase family of protein inositol monophosphatase (IMPase). Inositol monophosphatase, an enzyme involved in the phosphatidylinositol signalling pathway, is encoded by the IMPA1 gene. Homology Modelling is used to create a 3D model of the IMPA1 protein (target). The FASTA sequence for the IMPase protein (265 amino acids) (Uniprot ID H0YBL1) is obtained from the Uniprot server. Jpred, and NCBI Blast servers are used to search for templates. Based on the query coverage (92%) and E-score, the protein with the PDB ID-1IMA is identified as a potential template. The structural alignment (by ClustalW) submitted to the SWISS-MODEL service yields a 3D model. The Swiss PDB viewer is used to minimise energy (E = - 10099.60 kcal/mole). Procheck, ERRAT, and the VERIFY 3D server validate the model. The Ramachandran plot of the 3D model indicates that 93.5% of the amino acids are in the allowed region and none are in the forbidden region. The ERRAT result shows an overall quality factor of up to 96.17% for non-bonded atomic interactions. According to NCBI blast, the conserved domain is between 60 - 245 amino acids. The servers (ACTIVE SITE FINDER,) indicate binding pockets in the hydrophobic area, and Swiss dock is used to determine the active residues by protein - small ligand (Natural substrate, Fructose Biphosphatase-FBPase receptor) docking to identify the active site residues (Asp 90 and Thr-95) based on visualisations and a Swiss energy value. The glucose metabolism can be stopped by blocking these residues. Key Words: Diabetes, Phosphodiesterase family, Homology Modelling. [ABSTRACT FROM AUTHOR]

Understanding the structure and function of intermediate filaments (IFs) is necessary in order to explain why more than 70 related IF genes have evolved in vertebrates while maintaining such dramatically tissue-specific expression. Desmin is a member of the large multigene family of IF proteins and is specifically expressed in myocytes. In an effort to elucidate its muscle-specific behavior, we have used a yeast two-hybrid system in order to identify desmin's head binding partners. We described a mitochondrial and a lysosomal protein, NADH ubiquinone oxidoreductase core subunit S2 (NDUFS2), and saposin D, respectively, as direct desmin binding partners. In silico analysis indicated that both interactions at the atomic level occur in a very similar way, by the formation of a three-helix bundle with hydrophobic interactions in the interdomain space and hydrogen bonds at R16 and S32 of the desmin head domain. The interactions, confirmed also by GST pull-down assays, indicating the necessity of the desmin head domain and, furthermore, point out its role in function of mitochondria and lysosomes, organelles which are disrupted in myopathies due to desmin head domain mutations. [ABSTRACT FROM AUTHOR]

This study investigates the effects of increasing PbO concentration on the Al2O3–PbO–B2O3–SiO2 glasses' physical, mechanical and gamma ray shielding properties. PbO addition leads to higher density and molar mass, making the glass denser. However, molar volume decreases, indicating a more compact structure. Interatomic distances and ion concentration change, strengthening atomic interactions. Oxygen molar volume increases, but packing density drops with more PbO, impacting the glass lattice. Optical basicity rises, suggesting improved electron transport and optical behavior. Electronegativity decreases, and electronic polarizability increases with higher PbO content, rendering the glass more electron-donating and sensitive to external electric fields.This study investigates glass mechanical properties using the Makishima–Mackenzie model. As PbO concentration rises, elastic moduli consistently decrease, signifying increased flexibility in glass structures. The mass attenuation coefficients (MAC) of the chosen glasses were evaluated in the 0.284–1.333 MeV energy range. It was found that increased PbO content leads to a corresponding MAC enhancement. The MAC values at 0.284 MeV were 0.297 and 0.349 cm2/g, while at 0.511 MeV they varied between 0.124 and 0.135 cm2/g. It was found that Glass Pb47.5 sample, which contains a higher amount of PbO compared to the other glasses, had the highest MAC at all energies. The results showed that the PbO has a notable impact on the MAC and thus on the radiation attenuation performance at lower energy. Moreover, increased glass density led to a corresponding LAC increase, which at 0.284 MeV increased from 1.269 cm−1 for Pb32.5 to 1.898 cm−1 for Pb47.5. According to the LAC results, one simple means of enhancing the glasses' radiation shielding properties is utilizing a high PbO percentage. This paper aims to illuminate silicate glasses' radiation shielding abilities. The paper will investigate the efficiency under specific conditions, like high-energy radiation. Moreover, it will explore innovative methods to enhance their shielding competence, concreting the way for a better yet effective radiation shielding approach. [ABSTRACT FROM AUTHOR]

The optical properties and Landau quantisations in twisted bilayer graphene are investigated using a generalised tight-binding model that takes into account all interlayer and intralayer atomic interactions in the Moire superlattice. The system is a zero-gap semiconductor with double-degenerate Dirac-cone structures, and saddle-point energy dispersions appear at low energies for small twisting angles. The magnetic quantisation phenomena in this system are rich and unique, with Landau-level subgroups specified owing to specific Moire zone folding through modulation of the stacking angles. The Landau-level spectrum shows hybridised characteristics associated with those in monolayer, as well as AA and AB stackings. The detailed analysis explores the complex relations among the different sublattices on the same and different graphene layers. [ABSTRACT FROM AUTHOR]

Context: Density functional theory (DFT) was used to investigate the effects of varying carbon doping concentrations on the electronic and optical properties of SnS2-doped systems. The findings show that a doping concentration of 3.7% in SnS2 results in the highest structural stability and the lowest formation energy. A pure SnS2 monolayer is an indirect bandgap semiconductor, and the result reveals that increasing carbon doping correlates with a gradual reduction in the system's bandgap. The density of states analysis reveals that the valence band comprises C-2p, S-3p, and Sn-5p orbitals, whereas the conduction band consists of S-3p, Sn-5 s, and C-2p orbitals. Furthermore, doping concentration appears to cause a redshift in both the absorption coefficient and reflection peaks, which both decrease as doping concentration increases. Methods: The calculations for this study were performed using DFT within the CASTEP module of Materials Studio Segall et al. J Phys: Condens Matter 14(11):2717, 2002. The system parameters and structures were optimized to determine the electronic structure and optical properties. Geometric optimization and calculations were carried out with the generalized gradient approximation plane-wave pseudopotential method and the Perdew-Burke-Ernzerhof functional Perdew et al. Phys Rev Lett 80(4):891–891, 1998. The parameters for structural optimization included a plane-wave expansion cutoff energy set at 500 eV and a k-point mesh of 6 × 6 × 1 for Brillouin zone integration. The electronic convergence criteria were established at 1.0 × 10-5 eV/atom for the unit cell energy and 1.0 × 10-6 eV/atom for self-consistency. The internal stress deviation was maintained below 0.05 GPa, the atomic force interactions were kept under 0.03 eV/Å, and atomic displacements during geometric optimization were confined to less than 0.001 Å. To calculate the properties of the SnS2 monolayer, a vacuum spacing of 15 Å along the z-axis was introduced to prevent interactions between adjacent layers. [ABSTRACT FROM AUTHOR]

Studying the photoinduced changes of materials with atomic-scale spatial resolution can provide a fundamental understanding of light-matter interaction. A long-standing impediment has been the detrimental thermal effects on the stability of the tunneling gap from intensity-modulated laser irradiation of the scanning tunneling microscope junction. Photoinduced DC current transduces photons to an electric current and is widely applied in optoelectronics as switches and signal transmission. Our results revealed the origin of the light-induced DC current and related it to the two-level population dynamics and related nonlinearity in the conductance of a single molecule. Here, we compensated for the near-visible laser-induced thermal effects to demonstrate photoinduced DC current spectroscopy and microscopy and to observe the persistent photoconductivity of a two-level pyrrolidine molecule. The methodology can be generally applied to the coupling of light to scan probes to investigate light-matter interactions at the atomic scale. [ABSTRACT FROM AUTHOR]

Atomic force microscopy with a CO-functionalized tip can be used to directly image the internal structure of a planar molecule and to characterize chemical bonds. However, hydrogen atoms usually cannot be directly observed due to their small size. At the same time, these atoms are highly important, since they can direct on-surface chemical reactions. Measuring in-plane interactions at the sides of PTCDA (3,4,9,10-perylenetetracarboxylic dianhydride) molecules with lateral force microscopy allowed us to directly identify hydrogen atoms via their repulsive signature, which we confirmed with a model incorporating radially symmetric atomic interactions. Additional features were observed in the force data and could not be explained by H-bonding of the CO tip with the PTCDA sides. Instead, they are caused by electrostatic interaction of the large dipole of the metal apex, which we verified with density functional theory. This calculation allowed us to estimate the strength of the dipole at the metal tip apex. To further confirm that this dipole generally affects measurements on weakly polarized systems, we investigated the archetypical surface adsorbate of a single CO molecule. We determined the radially symmetric atomic interaction to be valid over a large solid angle of 5.4 sr, corresponding to 82°. We therefore find that in both the PTCDA and CO systems, the underlying interaction preventing direct observations of H-bonding and causing a collapse of the radially symmetric model is the dipole at the metal apex, which plays a significant role when approaching closer than standard imaging heights. [ABSTRACT FROM AUTHOR]

Ternary Cu 3 ZnSb adopts the tetrahedral space group P 4/ nmm (129), with 10 atoms in the unit cell, distributed over four crystallographic positions in a perfectly ordered manner. It possesses two perfect tetrahedral interstitial positions, namely Cu 3 Sb and Cu 2 Zn 2. The possible hydrogen storage properties in these two possible sites are explored by the aid of first-principles density functional theory calculations. The Cu-richer Cu 3 Sb site is energetically more favourable position for hydrogen atom, over the other one. The maximum possible H-uptake capacity would be within the range of ∼4 H per formula unit. The electronic structure modification, host-guest interactions, and electronic redistribution after hydrogen incorporation are explored from fundamental perspectives analyzing the density of states, crystal orbital Hamilton population, crystal orbital bond index, and Mulliken population calculations. [Display omitted] • The atomic hydrogen absorption properties of Cu 3 ZnSb have been explored by first-principles calculations. • The Cu-richer Cu 3 Sb site is energetically more favourable than the Cu 2 Zn 2 -site. • The electronic structure modification up on bulk hydrogenation was explored by comparing the density of states. • COHP and COBI calculations extract the detailed information of the host(H)-guest (IMC) interactions. • Mulliken population analysis confirms the electronic redistribution after hydrogenation. [ABSTRACT FROM AUTHOR]

The divergence-free nature of Bessel beams can be harnessed to effectively trap optical vortices in free space laser propagation. We show how to generate arbitrary vortex configurations in Bessel traps to investigate few-body vortex interactions within a dynamically evolving fluid of light, which is a formal analog to a non-interacting Bose gas. We implement—theoretically and experimentally—initial conditions of vortex configurations first predicted in harmonically trapped quantum fluids, in the limit of weak atomic interactions, and model and measure the resultant dynamics. These hard trap dynamics are distinct from the harmonic trap predictions due to the non-local interactions that occur among the hard-wall boundary and steep phase gradients that nucleate other vortices. By simultaneously presenting experimental demonstrations with the theoretical proposal, we validate the potential application of using Bessel hard-wall traps as testing grounds for engineering few-body vortex interactions within trapped, two-dimensional compressible fluids. [ABSTRACT FROM AUTHOR]

Free energies of a solid surface and a solid–liquid interface play significant roles in thermodynamics. Due to the limited availability of experimental data, computational methods offer effective alternatives for calculating these properties. This study adopts advanced frameworks of the logarithmic mean force dynamics method to present an enhanced sampling approach for the calculation of the free energy at different temperatures. To achieve this, the free energy profile is constructed along with a pre‐established collective variable within the melting transition and cleavage processes. The values of the solid surface and solid–liquid interface free energies are then extrapolated from the excess free energy related to the formation and persistence of the solid surface or the solid–liquid interface. Furthermore, this methodology is employed to calculate the temperature dependence of the free energy measurements for the (100) and (110) surfaces and interfaces of Cu. It is shown that this methodology is robust and readily applicable in contemporary models of atomic interactions and various systems. [ABSTRACT FROM AUTHOR]

The methods for forming hybrid organo-inorganic perovskite structures in the form of thin films and their stability are studied. The molecular-dynamics (MD) simulation approach was used to conduct theoretical analyses of materials based on the hybrid organo-inorganic perovskites MAPbX3. The classical perovskite structures based on CaTiO3 are considered the basic structure to refine the methodology of computer simulation and optimize the shape and parameters of the interaction of atomic potentials. Series of MD calculations with various model concepts, and models of flexible and rigid coupling of perovskites, the heating process's influence on the structure has been analyzed in a wide range. [ABSTRACT FROM AUTHOR]

Designing 3D molecules with high binding affinity for specific protein targets is crucial in drug design. One challenge is that the atomic interaction between molecules and proteins in 3D space has to be taken into account. However, the existing target-aware methods solely model the joint distribution between the molecules and proteins, disregarding the binding affinities between them, which leads to limited performance. In this paper, we propose an explainable diffusion model to generate molecules that can be bound to a given protein target with high affinity. Our method explicitly incorporates the chemical knowledge of protein–ligand binding affinity into the diffusion model, and uses the knowledge to guide the denoising process towards the direction of high binding affinity. Specifically, an SE(3)-invariant expert network is developed to fit the Vina scoring functions and jointly trained with the denoising network, while the domain knowledge is distilled and conveyed from Vina functions to the expert network. An effective guidance is proposed on both continuous atom coordinates and discrete atom types by taking advantages of the gradient of the expert network. Experiments on the benchmark CrossDocked2020 demonstrate the superiority of our method. Additionally, an atom-level explanation of the generated molecules is provided, and the connections with the domain knowledge are established. [ABSTRACT FROM AUTHOR]

Neurological and psychiatric disorders contribute significantly to the global disease burden, adversely affecting the quality of life for both patients and their families. Impaired glutamatergic signaling is considered to be a major cause for most of the neurological and psychiatric disorders. Glutamate receptors are over activated in excitotoxic conditions, leading to dysregulation of Ca2+ homeostasis, triggering the production of free radicals and oxidative stress, mitochondrial dysfunction and eventually cell death. Excitotoxicity primarily results from the overactivity of NMDARs, a subtype of ionotropic glutamate receptors, due to their pronounced Ca2+ permeability and conductance characteristics. NMDAR antagonists are suggested to have therapeutic use as they can prevent excitotoxicity. Our previous studies demonstrated lobeline, an alkaloid, exerts neuroprotective action in excitotoxic conditions by blocking NMDAR. However, the atomic level interactions of lobeline with NMDAR was not characterized yet. Structural comparison of lobeline with a known NMDAR antagonist ifenprodil, followed by molecular docking and dynamics simulations revealed that lobeline could bind to the ifenprodil binding site i.e., in the heterodimer interface of GluN1-GluN2B subunits and exert ifenprodil like activities. By in silico structure guided modifications on lobeline and subsequent free energy calculations, we propose putative NMDAR antagonists derived from lobeline. [ABSTRACT FROM AUTHOR]

A series of phthalimide-capped benzene sulphonamides (1–22) reported by our group for dengue protease inhibitory activity have been evaluated for their carbonic anhydrase (hCA, EC 4.2.1.1) inhibitory activity against hCA I, hCA II. Compounds 1, 3, 10, and 15 showed hCA I inhibition, whereas 1, 4, and 10 showed hCA II inhibition at nanomolar concentrations. Among these compounds, 1 displayed potent inhibitory activity against the hCA I (Ki = 28.5 nM) and hCA II (Ki = 2.2 nM), being 10 and 6 times more potent than acetazolamide, a standard inhibitor (Ki = 250 nM and 12 nM), respectively. Furthermore, this compound displayed 14-fold selectivity towards the hCA II isoform compared to hCA I. Molecular docking and MD simulations were performed to understand the atomic level interactions responsible for the selectivity of compound 1 towards hCA II. [ABSTRACT FROM AUTHOR]

Understanding hydrogen incorporation into palladium requires detailed knowledge of surface and subsurface structure and atomic interactions as surface hydrogen is being embedded. Using density functional theory (DFT), we examine the energies of hydrogen layers of varying coverage adsorbed on Pd(111). We find that H–H and H–Pd interactions promote the formation of the well-known 3 × 3 phases but also favor an unreported (3 × 3) phase at high H coverages for which we present experimental evidence. We relate the stability of isolated H vacancies of the (3 × 3) phase to the need of H2 molecules to access bare Pd before they can dissociate. Following higher hydrogen dosage, we observe initial steps of hydride formation, starting with small clusters of subsurface hydrogen. The interaction between H and Pd is complicated by the persistent presence of carbon at the surface. X-ray photoelectron spectroscopy experiments show that trace amounts of carbon, emerging from the Pd bulk despite many surface cleaning cycles, become mobile enough to repopulate the C-depleted surface at temperatures above 200 K. When exposed to hydrogen, these surface carbon atoms react to form benzene, as evidenced by scanning tunneling microscopy observations interpreted with DFT. [ABSTRACT FROM AUTHOR]

Remote epitaxy is a recently discovered type of epitaxy, wherein single-crystalline thin films can be grown on graphene-coated substrates following the crystallinity of the substrate via remote interaction through graphene. Although remote epitaxy provides a pathway to form freestanding membranes by controlled exfoliation of grown film at the graphene interface, implementing remote epitaxy is not straightforward because atomically precise control of interface is required. Here, we unveil the role of the graphene–substrate interface on the remote epitaxy of GaAs by investigating the interface at the atomic scale. By comparing remote epitaxy on wet-transferred and dry-transferred graphene, we show that interfacial oxide layer formed at the graphene–substrate interface hinders remote interaction through graphene when wet-transferred graphene is employed, which is confirmed by an increase of interatomic distance through graphene and also by the formation of polycrystalline films on graphene. On the other hand, when dry-transferred graphene is employed, the interface is free of native oxide, and single-crystalline remote epitaxial films are formed on graphene, with the interatomic distance between the epilayer and the substrate matching with the theoretically predicted value. The first atomic layer of the grown film on graphene is vertically aligned with the top layer of the substrate with these atoms having different polarities, substantiating the remote interaction of adatoms with the substrate through graphene. These results directly show the impact of interface properties formed by different graphene transfer methods on remote epitaxy. [ABSTRACT FROM AUTHOR]

A new approach termed Adaptive Solvent-Scaling (AdSoS) is introduced for performing simulations of a solute embedded in a fine-grained (FG) solvent region itself surrounded by a coarse-grained (CG) solvent region, with a continuous FG ↔ CG switching of the solvent resolution across a buffer layer. Instead of relying on a distinct CG solvent model, the AdSoS scheme is based on CG models defined by a dimensional scaling of the FG solvent by a factor s, accompanied by an s-dependent modulation of the atomic masses and interaction parameters. The latter changes are designed to achieve an isomorphism between the dynamics of the FG and CG models, and to preserve the dispersive and dielectric solvation properties of the solvent with respect to a solute at FG resolution. This scaling approach offers a number of advantages compared to traditional coarse-graining: (i) the CG parameters are immediately related to those of the FG model (no need to parameterize a distinct CG model); (ii) nearly ideal mixing is expected for CG variants with similar s-values (ideal mixing holding in the limit of identical s-values); (iii) the solvent relaxation timescales should be preserved (no dynamical acceleration typical for coarse-graining); (iv) the graining level NG (number of FG molecules represented by one CG molecule) can be chosen arbitrarily (in particular, NG = s3 is not necessarily an integer); and (v) in an adaptive-resolution scheme, this level can be varied continuously as a function of the position (without requiring a bundling mechanism), and this variation occurs at a constant number of particles per molecule (no occurrence of fractional degrees of freedom in the buffer layer). By construction, the AdSoS scheme minimizes the thermodynamic mismatch between the different regions of the adaptive-resolution system, leading to a nearly homogeneous scaled solvent density s3ρ. Residual density artifacts in and at the surface of the boundary layer can easily be corrected by means of a grid-based biasing potential constructed in a preliminary pure-solvent simulation. This article introduces the AdSoS scheme and provides an initial application to pure atomic liquids (no solute) with Lennard-Jones plus Coulomb interactions in a slab geometry. [ABSTRACT FROM AUTHOR]

The effect of strontium substitution in the structure of the complex oxide Gd2SrFe2O7 on the production of light olefins by CO hydrogenation was investigated. Perovskite-type oxides Gd2−xSr1+xFe2O7 (x = 0; 0.1; 0.2; 0.3; 0.4) were synthesized by sol–gel technology and characterized by XRD, Mössbauer spectroscopy, BET specific area, acidity testing, and SEM. The experimental data revealed a correlation between the state of iron atoms, acidity, and catalytic performance. It was found that with an increase in the content of Sr2+ in the perovskite phase, the basicity of the surface and the oxygen diffusion rate increased. This contributed to the CO dissociative adsorption, formation of active carbon, and its further interaction with atomic hydrogen. [ABSTRACT FROM AUTHOR]

An Online tool for Fragment-based Molecule Parametrization (OFraMP) is described. OFraMP is a web application for assigning atomic interaction parameters to large molecules by matching sub-fragments within the target molecule to equivalent sub-fragments within the Automated Topology Builder (ATB, atb.uq.edu.au) database. OFraMP identifies and compares alternative molecular fragments from the ATB database, which contains over 890,000 pre-parameterized molecules, using a novel hierarchical matching procedure. Atoms are considered within the context of an extended local environment (buffer region) with the degree of similarity between an atom in the target molecule and that in the proposed match controlled by varying the size of the buffer region. Adjacent matching atoms are combined into progressively larger matched sub-structures. The user then selects the most appropriate match. OFraMP also allows users to manually alter interaction parameters and automates the submission of missing substructures to the ATB in order to generate parameters for atoms in environments not represented in the existing database. The utility of OFraMP is illustrated using the anti-cancer agent paclitaxel and a dendrimer used in organic semiconductor devices. OFraMP applied to paclitaxel (ATB ID 35922). [ABSTRACT FROM AUTHOR]

Embodying the indexical signs is vital to semiosis as a cohesive material agency mediating between consequents and antecedents. One unique factor of biology compared with standard physics and chemistry is the cohesion enabling the biological components, codes and organizations to accommodate themselves with a specific material embodiment. Every individual body is uniquely biological and requires a specific cohesion of material origin for its own sake that could not be found in the non-living material world. The relevant cohesion comes from the exchange interaction of the atomic quantum particles, such as the carbon atoms, which is far greater than the electrons as a common exchange mediator adopted for the spatial cohesion ubiquitous in physics and chemistry. What is specific to the temporal cohesion latent in the atomic exchange is the immutable identity of the individual quantum particle surviving only over a limited time, while being constantly alternated with the new ones of the same kinds in a successive manner. Semiosis is supported by the underlying teleonomic cohesion, such that the preceding temporal cohesion may constantly induce the succeeding similar one ad infinitum. [ABSTRACT FROM AUTHOR]

Many-body interactions and correlations in atomic ensembles are fundamental in understanding many-body effects such as collective and emergent phenomena and also play an important role in various atom-based applications. Optical two-dimensional coherent spectroscopy (2DCS) provides a powerful tool to measure many-body interactions and correlations. Here, we present the study of many-body dipole–dipole interactions and correlations in potassium and rubidium atomic vapors by using double-quantum and multi-quantum 2DCS. The results show that double-quantum 2DCS provides sensitive and background-free detection of weak dipole–dipole interaction between atoms with a mean separation up to about 16 μm, and multi-quantum 2DCS can excite and detect multi-atom states (Dicke states) with up to eight correlated atoms. The technique of optical 2DCS can provide a new approach to study many-body physics in atomic ensembles and can be potentially implemented to measure many-body effects in cold atoms and other atomic/molecular systems. [ABSTRACT FROM AUTHOR]

Molecular Dynamics (MD) simulations are uniquely suitable for providing molecular-level insights into the Electric Double Layer (EDL) that forms when a charged surface is in contact with an aqueous solution. However, simulations are only as accurate in predicting EDL properties as permitted by the atomic interaction models. Experimental ζ-potential values and surface charges could provide a potentially suitable reference to validate and tune the interaction models, if not for the fact that they themselves are a product of imperfect models used to interpret the raw measurement data. Here, we present an approach to tune an interaction model by comparing Electro-Osmotic Flow (EOF) MD simulations against experimental Streaming Current (SC) measurements while minimizing potential modeling errors arising from both approaches. The point that is least susceptible to interpretation and modeling errors is argued to be at the concentration for which zero flow velocity is observed in EOF simulations and a net zero electric current is measured in SC experiments. At this concentration, the ζ-potential is also zero. We were able to match the experimental concentration at which ζ = 0 in MD simulations for a CaCl2 solution at pH 7.5 in contact with fused silica by tuning the ion-surface Lennard-Jones cross interactions. These interactions were found to greatly affect the ion distribution within the EDL and particularly the formation of inner-sphere surface-complexes, which, in turn, affects the electrokinetic flow. With the ion distribution determined explicitly, a series of properties can be calculated unambiguously, such as the capacitance needed for surface complexation models. [ABSTRACT FROM AUTHOR]

The Hall effect, which originates from the motion of charged particles in magnetic fields, has deep consequences for the description of materials, extending far beyond condensed matter. Understanding such an effect in interacting systems represents a fundamental challenge, even for small magnetic fields. In this work, we used an atomic quantum simulator in which we tracked the motion of ultracold fermions in two-leg ribbons threaded by artificial magnetic fields. Through controllable quench dynamics, we measured the Hall response for a range of synthetic tunneling and atomic interaction strengths. We unveil a universal interaction-independent behavior above an interaction threshold, in agreement with theoretical analyses. The ability to reach hard-to-compute regimes demonstrates the power of quantum simulation to describe strongly correlated topological states of matter. [ABSTRACT FROM AUTHOR]

Short‐range order (SRO) in the liquid Al−Ni−Sn alloys has been investigated using the X‐ray diffraction method and Reverse Monte Carlo simulations. Obtained results point out a micro‐inhomogeneous structure of Al−Sn−Ni melts with Sn content between 10 and 65 at.% due to the presence of atomic clusters with the structure of liquid Sn and atomic clusters with Ni−Sn coordination. The influence of the atomic size ratio (size factor) and pair atomic interactions (energy factor) on the short‐range order of the investigated ternary melts are discussed. There is a competition between Al and Sn atoms in the formation of the SRO around Ni atoms due to the difference in bond energy in Ni−Al and Ni−Sn pairs. This competition, as well as a bigger radius of Sn atoms, results in the formation of atomic clusters with liquid Sn‐like local atomic structure. [ABSTRACT FROM AUTHOR]

Single-phase high-entropy rare-earth zirconate (Dy 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Yb 0.2) 2 Zr 2 O 7 with excellent high-temperature phase stability at 1600 °C was designed and synthesized. After being heated at 1600 °C for 1 ∼ 50 h, the average grain size of the sample increases only from 0.74 μm to 2.22 μm, indicating a high anti-sintering ability. The fracture toughness is 2.07 ± 0.03 MPa m1/2 (25 °C), which is 50% higher than lanthanum zirconate. The local lattice distortions induced by the atomic interactions and atomic-size mismatch are considered to be responsible for the strong anti-sintering ability and improved fracture toughness. In addition, the thermal expansion coefficient and thermal conductivity of (Dy 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Yb 0.2) 2 Zr 2 O 7 are 10.59 × 10-6 K-1 (25 ∼ 1500 °C) and 1.14 ± 0.09 W·m-1·K-1 (1500 °C), respectively. The outstanding combination of anti-sintering ability, mechanical behavior, and thermophysical properties of (Dy 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Yb 0.2) 2 Zr 2 O 7 highlights its great potential for next-generation thermal barrier coating applications. [ABSTRACT FROM AUTHOR]

A semi-classical anharmonic correlated Einstein model of hcp crystals is derived for the high-order expanded Debye-Waller factors and extended X-ray absorption fine structure. The many-body effect is included in this model based on the contributions of the first shell near neighbors of the absorber and backscatter atoms. The analytical expressions of Debye-Waller factors presented in terms of cumulant expansion up to the fourth order yield results based on the classical theory corrected for its absence of zero-point vibration. The anharmonic many-body effect effective potential is derived which includes the Morse potential for describing the single-pair atomic interactions. A method of providing all extended X-ray absorption fine structure quantities is created, correcting the absence of zero-point vibration in classical theory, combining it with the quantum one based on only the second cumulant. The derived model has the advantage of including both classical and quantum effects. The numerical results of all considered quantities of Zn (hcp) are found to be in good agreement with the experimental values. [ABSTRACT FROM AUTHOR]

Group IIIA elements are electron deficient, and the transition metal doped clusters can be used to build cluster-based materials. This paper study the global lowest energy structures of In8FeNan (n = 0, 2, 4, 6, 8) by using evolutionary algorithm combined with spin polarized density functional theories. The electronic structures show that the Na atoms donate electrons to the In8Fe core and combine on the peripheries of the clusters through electrostatic interactions. Analyses on density of states and molecular orbitals reveal that the 5s orbitals of In atoms do not mix with other atomic orbitals and form superatomic orbitals with lower energies. The 3d orbitals of Fe atom interact strongly with the superatomic orbitals formed by In 5p. Different interaction patterns compete and it makes the lowest electronic ground states be singlet or triplet. In the triplet states of In8FeNan, the α orbitals have three or four 3d orbitals localized on the Fe atom. For the singlet states, there exists no pure 3d atomic orbitals and the upper valence states show obvious features of bonding or antibonding interactions between atomic Fe 3d and superatomic orbitals composed of In 5p. The strong orbital interactions enhance significantly the stabilities of the clusters. [ABSTRACT FROM AUTHOR]

The harsh working environments of proton exchange membrane fuel cells (PEMFCs) pose huge challenges to the stability of Pt‐based alloy catalysts. The widespread presence of metallic bonds with significantly delocalized electron distribution often lead to component segregation and rapid performance decay. Here we report L10−Pt2CuGa intermetallic nanoparticles with a unique covalent atomic interaction between Pt−Ga as high‐performance PEMFC cathode catalysts. The L10−Pt2CuGa/C catalyst shows superb oxygen reduction reaction (ORR) activity and stability in fuel cell cathode (mass activity=0.57 A mgPt−1 at 0.9 V, peak power density=2.60/1.24 W cm−2 in H2‐O2/air, 28 mV voltage loss at 0.8 A cm−2 after 30 000 cycles). Theoretical calculations reveal the optimized adsorption of oxygen intermediates via the formed biaxial strain on L10−Pt2CuGa surface, and the durability enhancement stems from the stronger Pt−M bonds than those in L11−PtCu resulted from Pt−Ga covalent interactions. [ABSTRACT FROM AUTHOR]

The harsh working environments of proton exchange membrane fuel cells (PEMFCs) pose huge challenges to the stability of Pt‐based alloy catalysts. The widespread presence of metallic bonds with significantly delocalized electron distribution often lead to component segregation and rapid performance decay. Here we report L10−Pt2CuGa intermetallic nanoparticles with a unique covalent atomic interaction between Pt−Ga as high‐performance PEMFC cathode catalysts. The L10−Pt2CuGa/C catalyst shows superb oxygen reduction reaction (ORR) activity and stability in fuel cell cathode (mass activity=0.57 A mgPt−1 at 0.9 V, peak power density=2.60/1.24 W cm−2 in H2‐O2/air, 28 mV voltage loss at 0.8 A cm−2 after 30 000 cycles). Theoretical calculations reveal the optimized adsorption of oxygen intermediates via the formed biaxial strain on L10−Pt2CuGa surface, and the durability enhancement stems from the stronger Pt−M bonds than those in L11−PtCu resulted from Pt−Ga covalent interactions. [ABSTRACT FROM AUTHOR]

A computationally efficient mixed atomistic-continuum coupled modelling is employed to investigate the vibrational characteristics and large deformation static response of some nitride and phosphide-based nanotubes. The atomic entities bond lengths/angles and continuum entities strains/curvature tensors are coupled through the kinematics of quadratic-type Cauchy–Born rule considering curvature effects on the atomic entities. The finite element model is formulated in a cylindrical coordinate system considering geometric nonlinearity through nonlinear strain–displacement relations and material nonlinearity through interatomic potential. The present study is carried out using a four nodded membrane consistent element wherein smoothened interpolation functions derived through least square minimization are used to interpolate the circumferential strain to avoid membrane locking. The atomic interactions are modelled using Tersoff–Brenner type interatomic potential with recently reported new empirical parameters. The effects of length and diameter, boundary conditions and length-to-diameter ratio on the natural frequency of the different nanotubes are also reported. The results obtained through multiscale modelling are also compared with those obtained through molecular dynamics (MD) simulation. The effect of material nonlinearity on the fundamental frequency of the nanotubes under applied pressure is also reported. [ABSTRACT FROM AUTHOR]

Procedures are developed for accelerated laboratory tests of spacecraft polymers for resistance to long-term exposure to hyperthermal atomic oxygen (AO) with the use of high-energy AO ions of a rarefied plasma and Kapton-H polyimide as the reference material. The parameters that characterize physico-chemical, thermo-optical, and aerodynamic AO – Kapton-H interaction (surface roughness, solar absorptance, and normal infrared emittance) are determined at different values of the AO fluence. To do this, use was made of the data of tests onboard spacecraft in the Earth's atmosphere and the authors and others' laboratory tests. The normal and the tangential momentum transfer coefficient and the energy transfer coefficient are reported as a function of the AO bombardment angle. The obtained data on the AO-induced degradation of the parameters that characterize AO–polyimide dynamic interaction allow one to predict the behavior of the polyimide thermo-optical and aerodynamic properties during a long-term service in the Earth's upper atmosphere and ionosphere. • Physical modeling conditions for spacecraft – atomic oxygen interaction are given. • Atomic oxygen to polyimide momentum and energy transport coefficients are measured. • Atomic oxygen induced polyimide degradation parameters are determined. [ABSTRACT FROM AUTHOR]

The solvation of sugars in aqueous media matters in the understanding of biological systems and carbohydrate transformations. The presence of NaCl is known to perturb hydrogen bonding of sugar hydrates, however, direct evidence to elucidate mechanism at atom level is very rare even though the "NaCl Effect" was well known in biomass transformations for chemicals/biofuels. Here we report experimental evidences of a clear staircase‐like correlation between induced 1H NMR changes of D‐glucose/fructose with concentration of NaCl aqueous solution at room temperature; and two stable bonding status was observed in the system. HDO in sugar/NaCl aqueous solution as a "dynamic" reference is a key to enable decoupling the global salt effect in this 1H NMR investigation of NaCl‐saccharide interaction. Via a further half‐quantitative study, three structures of stable sugar‐NaCl‐water complexes were mapped for the first time in tackling the NaCl‐monosaccharide interaction at atomic level in an aqueous solution. Based on the maximum of induced 1H NMR shifts, an ideal NaCl usage was proposed. [ABSTRACT FROM AUTHOR]

Adsorption of atomic oxygen on the surface of polycrystalline gold is studied in detail by XPS and TPD methods. It is shown that the action of atomic oxygen at initial stages leads to the formation of chemisorbed atomic oxygen with the deposition thickness Θ = 0–0.5 monolayers. Increased exposure to atomic oxygen leads to the formation of 2D gold oxide. At the maximum oxygen saturation, the calculated oxide layer thickness is 3 Å, and its stoichiometry is close to AuO2. The TPD analysis shows that thermal stability of adsorbed oxygen is 510 K for the chemisorbed layer and 525 K for the 2D gold oxide. The structure of the 2D gold oxide is determined as one layer of gold atoms and two layers of oxygen atoms adsorbed on the surface and inside the subsurface layer. The reactivity of adsorbed oxygen is tested by the interaction of CO and H2 at room temperature; all the oxygen forms are shown to be active. It is established that the reactivity towards CO is 2 orders of magnitude higher than towards H2, suggesting that oxygen species take part in the PROX mechanism. [ABSTRACT FROM AUTHOR]