Structural transition and migration of incoherent twin boundary in diamond.

Grain boundaries (GBs), with their diversity in both structure and structural transitions, play an essential role in tailoring the properties of polycrystalline materials1-5. As a unique GB subset, {112} incoherent twin boundaries (ITBs) are ubiquitous in nanotwinned, face-centred cubic materials6-9. Although multiple ITB configurations and transitions have been reported7,10, their transition mechanisms and impacts on mechanical properties remain largely unexplored, especially in regard to covalent materials. Here we report atomic observations of six ITB configurations and structural transitions in diamond at room temperature, showing a dislocation-mediated mechanism different from metallic systems11,12. The dominant ITBs are asymmetric and less mobile, contributing strongly to continuous hardening in nanotwinned diamond13. The potential driving forces of ITB activities are discussed. Our findings shed new light on GB behaviour in diamond and covalent materials, pointing to a new strategy for development of high-performance, nanotwinned materials.

Ultrastrong conductive in situ composite composed of nanodiamond incoherently embedded in disordered multilayer graphene.

Traditional ceramics or metals cannot simultaneously achieve ultrahigh strength and high electrical conductivity. The elemental carbon can form a variety of allotropes with entirely different physical properties, providing versatility for tuning mechanical and electrical properties in a wide range. Here, by precisely controlling the extent of transformation of amorphous carbon into diamond within a narrow temperature-pressure range, we synthesize an in situ composite consisting of ultrafine nanodiamond homogeneously dispersed in disordered multilayer graphene with incoherent interfaces, which demonstrates a Knoop hardness of up to ~53 GPa, a compressive strength of up to ~54 GPa and an electrical conductivity of 670-1,240 S m-1 at room temperature. With atomically resolving interface structures and molecular dynamics simulations, we reveal that amorphous carbon transforms into diamond through a nucleation process via a local rearrangement of carbon atoms and diffusion-driven growth, different from the transformation of graphite into diamond. The complex bonding between the diamond-like and graphite-like components greatly improves the mechanical properties of the composite. This superhard, ultrastrong, conductive elemental carbon composite has comprehensive properties that are superior to those of the known conductive ceramics and C/C composites. The intermediate hybridization state at the interfaces also provides insights into the amorphous-to-crystalline phase transition of carbon.

Rational Functionalization of UiO-66 with Pd Nanoparticles: Synthesis and In Situ Fourier-Transform Infrared Monitoring.

Functionalization of metal-organic frameworks (MOFs) with noble metal nanoparticles (NPs) is a challenging task. Conventional impregnation by metals often leads to agglomerates on the surface of MOF crystals. Functional groups on linkers interact with metal precursors and promote the homogeneous distribution of NPs in the pores of MOFs, but their uncontrolled localization can block channels and thus hinder mass transport. To overcome this problem, we created nucleation centers only in the defective pores of the UiO-66 MOF via the postsynthesis exchange. First, we have introduced defects into UiO-66 using benzoic acid as a modulator. Second, the modulator was exchanged for amino-benzoic acid. As a result, amino groups have decorated mainly the defective pores and attracted the Pd precursor after impregnation. The interaction of the metal precursor with amino groups and the growth of NPs were monitored by in situ infrared spectroscopy. Three processes were distinguished: the gaseous HCl release, NH2 reactivation, and growth of extended Pd surfaces. Uniform Pd NPs were located in the pores because of the homogeneous distribution of the precursor and pore diffusion-limited nucleation rate. Our work demonstrates an alternative approach of controlled Pd incorporation into UiO-66 that is of great importance for the rational design of heterogeneous catalysts.

Integrated Video and Acoustic Emission Data Fusion for Intelligent Decision Making in Material Surface Inspection System.

In the field of intelligent surface inspection systems, particular attention is paid to decision making problems, based on data from different sensors. The combination of such data helps to make an intelligent decision. In this research, an approach to intelligent decision making based on a data integration strategy to raise awareness of a controlled object is used. In the following article, this approach is considered in the context of reasonable decisions when detecting defects on the surface of welds that arise after the metal pipe welding processes. The main data types were RGB, RGB-D images, and acoustic emission signals. The fusion of such multimodality data, which mimics the eyes and ears of an experienced person through computer vision and digital signal processing, provides more concrete and meaningful information for intelligent decision making. The main results of this study include an overview of the architecture of the system with a detailed description of its parts, methods for acquiring data from various sensors, pseudocodes for data processing algorithms, and an approach to data fusion meant to improve the efficiency of decision making in detecting defects on the surface of various materials.

Structural, Electronic, Reactivity, and Conformational Features of 2,5,5-Trimethyl-1,3,2-diheterophosphinane-2-sulfide, and Its Derivatives: DFT, MEP, and NBO Calculations.

In this study, we used density functional theory (DFT) and natural bond orbital (NBO) analysis to determine the structural, electronic, reactivity, and conformational features of 2,5,5-trimethyl-1,3,2-di-heteroatom (X) phosphinane-2-sulfide derivatives (X = O (compound 1), S (compound 2), and Se (compound 3)). We discovered that the features improve dramatically at 6-31G** and B3LYP/6-311+G** levels. The level of theory for the molecular structure was optimized first, followed by the frontier molecular orbital theory development to assess molecular stability and reactivity. Molecular orbital calculations, such as the HOMO-LUMO energy gap and the mapping of molecular electrostatic potential surfaces (MEP), were performed similarly to DFT calculations. In addition, the electrostatic potential of the molecule was used to map the electron density on a surface. In addition to revealing molecules' size and shape distribution, this study also shows the sites on the surface where molecules are most chemically reactive.

Application of XAFS and XRD methods for describing the copper and zinc adsorption characteristics in hydromorphic soils.

Modeling metal sorption in soils is of great importance to predict the fate of heavy metals and to assess the actual risk driven from pollution. The present study focuses on adsorption of HM ions on two types of hydromorphic soils, including calcaric fluvisols loamic and calcaric fluvic arenosols. The individual and competitive adsorption behaviors of Cu and Zn on soils and soil constituents are evaluated comprehensively. It is established that the sorption processes were best described with the Langmuir model. The results suggest that the calcaric fluvic arenosols are more vulnerable to heavy metal input compared to fluvisols loamic. In all cases, Cu had a higher range of values of the adsorption process parameters relative to Zn. The Zn is likely to be the most critical environmental factor in such soils since it exhibited a decreased sorption under competitive conditions. The retention mechanisms of HM in hydromorphic soils are considered. Based on theoretical calculations of ion activity in soil solutions using solubility diagrams of Cu and Zn compounds, the possibility of precipitation of Cu hydroxide and Zn carbonate in the studied soils is shown. Direct physical methods of nondestructive testing (XAFS and XRD) are applied to experimentally prove the formation of these HM compounds on the surface of montmorillonite, the dominant mineral in hydromorphic soils, and calcite. Thus, the combination of both physicochemical methods and direct physical methods can provide a large amount of real information about the mechanisms of HM retain with solid phases.

Deciphering the Phillips Catalyst by Orbital Analysis and Supervised Machine Learning from Cr Pre-edge XANES of Molecular Libraries.

Unveiling the nature and the distribution of surface sites in heterogeneous catalysts, and for the Phillips catalyst (CrO3/SiO2) in particular, is still a grand challenge despite more than 60 years of research. Commonly used references in Cr K-edge XANES spectral analysis rely on bulk materials (Cr-foil, Cr2O3) or molecules (CrCl3) that significantly differ from actual surface sites. In this work, we built a library of Cr K-edge XANES spectra for a series of tailored molecular Cr complexes, varying in oxidation state, local coordination environment, and ligand strength. Quantitative analysis of the pre-edge region revealed the origin of the pre-edge shape and intensity distribution. In particular, the characteristic pre-edge splitting observed for Cr(III) and Cr(IV) molecular complexes is directly related to the electronic exchange interactions in the frontier orbitals (spin-up and -down transitions). The series of experimental references was extended by theoretical spectra for potential active site structures and used for training the Extra Trees machine learning algorithm. The most informative features of the spectra (descriptors) were selected for the prediction of Cr oxidation states, mean interatomic distances in the first coordination sphere, and type of ligands. This set of descriptors was applied to uncover the site distribution in the Phillips catalyst at three different stages of the process. The freshly calcined catalyst consists of mainly Cr(VI) sites. The CO-exposed catalyst contains mainly Cr(II) silicates with a minor fraction of Cr(III) sites. The Phillips catalyst exposed to ethylene contains mainly highly coordinated Cr(III) silicates along with unreduced Cr(VI) sites.

Hydrogenation of ethylene over palladium: evolution of the catalyst structure by operando synchrotron-based techniques.

Palladium-based catalysts are exploited on an industrial scale for the selective hydrogenation of hydrocarbons. The formation of palladium carbide and hydride phases under reaction conditions changes the catalytic properties of the material, which points to the importance of operando characterization for determining the relation between the relative fractions of the two phases and the catalyst performance. We present a combined time-resolved characterization by X-ray absorption spectroscopy (in both near-edge and extended regions) and X-ray diffraction of a working palladium-based catalyst during the hydrogenation of ethylene in a wide range of partial pressures of ethylene and hydrogen. Synergistic coupling of multiple techniques allowed us to follow the structural evolution of the palladium lattice as well as the transitions between the metallic, hydride and carbide phases of palladium. The nanometric dimensions of the particles resulted in the considerable contribution of both surface and bulk carbides to the X-ray absorption spectra. During the reaction, palladium carbide is formed, which does not lead to a loss of activity. Unusual contraction of the unit cell parameter of the palladium lattice in the spent catalyst was observed upon increasing hydrogen partial pressure.

Speciation of Zn and Cu in Technosol and evaluation of a sequential extraction procedure using XAS, XRD and SEM-EDX analyses.

Metal speciation, linked directly to bioaccessibility and lability, is a key to be considered when assessing associated human and environmental health risks originated from anthropogenic activities. To identify the Zn and Cu speciation in the highly contaminated, technogenically transformed soils (Technosol) from the impact zone near the industrial sludge reservoirs of chemical plant (Siverskyi Donets River floodplain, southern Russia), the validity of the BCR sequential extraction procedure using the X-ray absorption fine-structure and X-ray powder diffraction (XRD) analyses was examined after each of the three stages. After the removal of exchange and carbonate-bonded Zn and Cu compounds from Technosol (first stage of extraction), the resulting residual soil showed enrichment in a great diversity of metal compounds, primarily with Me-S and Me-O bonds. The number of compounds with a higher solubility decreased at the subsequent stages of extraction. In the residual soil left over after extracting the first and second fractions, the dominant Zn-S bond appeared as würtzite (hexagonal ZnS) that made up more than 50%, while the Cu-S bond was almost completely represented only by chalcocite (Cu2S). The XRD analysis revealed the authigenic minerals of metals with S: sphalerite (cubic ZnS), würtzite (hexagonal ZnS), covellite (CuS) and bornite (Cu5FeS4). The scanning electron microscopy data confirmed that würtzite was the dominant form of Me with sulfur-containing and carbonate-containing minerals. The Zn-S bond was the main component (57%), whereas the Cu-O bond was dominant in the residual fraction (the fraction after the third-stage extraction). The results revealed that the composition of the residual fractions might include some of the most stable and hard-to-recover metal compounds of technogenic origin. Thus, the application of the novel instrumental methods, coupled with the chemical fractionation, revealed the incomplete selectivity of the extractants in the extraction of Zn and Cu in long-term highly contaminated soils.

ᶫ-Leucine Loading and Release in MIL-100 Nanoparticles.

Synthesis of the MIL-100 metal-organic framework particles was carried out by hydrothermal (HT) and microwave (MW)-assisted methods. Transmission electron microscopy showed formation of microparticles in the course of hydrothermal synthesis and nanoparticles for microwave-assisted synthesis. Powder X-ray diffraction confirmed formation of larger crystallites for hydrothermal synthesis. Particle aggregation in aqueous solution was observed by dynamic light scattering. However, the stability of both samples could be improved in acetic acid solution. Nitrogen sorption isotherms showed high porosity of the particles. ᶫ-leucine molecule was used as a model molecule for loading in the porous micro- and nanoparticles. Loading was estimated by FTIR spectroscopy and thermogravimetric analysis. UV-VIS spectroscopy quantified ᶫ-leucine release from the particles in aqueous solution. Cytotoxicity studies using the HeLa cell model showed that the original particles were somewhat toxic, but ᶫ-leucine loading ameliorated the toxic effects, likely due to signaling properties of the amino acid.

Partial and Complete Substitution of the 1,4-Benzenedicarboxylate Linker in UiO-66 with 1,4-Naphthalenedicarboxylate: Synthesis, Characterization, and H2-Adsorption Properties.

We describe the synthesis and corresponding full characterization of the set of UiO-66 metal-organic frameworks (MOFs) with 1,4-benzenedicarboxylate (C6H4(COOH)2, hereafter H2BDC) and 1,4-naphthalenedicarboxylate (C10H6(COOH)2, hereafter H2NDC) mixed linkers with NDC contents of 0, 25, 50, and 100%. Their structural (powder X-ray diffraction, PXRD), adsorptive (N2, H2, and CO2), vibrational (IR/Raman), and thermal stability (thermogravimetric analysis, TGA) properties quantitatively correlate with the NDC content in the material. The UiO-66 phase topology is conserved at all relative fractions of BDC/NDC. The comparison between the synchrotron radiation PXRD and 77 K N2-adsorption isotherms obtained on the 50:50 BDC/NDC sample and on a mechanical mixture of the pure BDC and NDC samples univocally proves that in the mixed linkers of the MOFs the BDC and NDC linkers are shared in each MOF crystal, discarding the hypothesis of two independent phases, where each crystal contains only BDC or NDC linkers. The careful tuning of the NDC content opens a way for controlled alteration of the sorption properties of the resulting material as testified by the H2-adsorption experiments, showing that the relative ranking of the materials in H2 adsorption is different in different equilibrium-pressure ranges: at low pressures, 100NDC is the most efficient sample, while with increasing pressure, its relative performance progressively declines; at high pressures, the ranking follows the BDC content, reflecting the larger internal pore volume available in the MOFs with a higher fraction of smaller linkers. The H2-adsorption isotherms normalized by the sample Brunauer-Emmett-Teller specific surface area show, in the whole pressure range, that the surface-area-specific H2-adsorption capabilities in UiO-66 MOFs increase progressively with increasing NDC content. Density functional theory calculations, using the hybrid B3LYP exchange correlation functional and quadruple-ζ with four polarization functions (QZ4P) basis set, show that the interaction of H2 with the H2NDC linker results in an adsorption energy larger by about 15% with respect to that calculated for adsorption on the H2BDC linker.

Fluorescence-detected XAS with sub-second time resolution reveals new details about the redox activity of Pt/CeO2 catalyst.

A setup for fluorescence-detected X-ray absorption spectroscopy (XAS) with sub-second time resolution has been developed. This technique allows chemical speciation of low-concentrated materials embedded in highly absorbing matrices, which cannot be studied using transmission XAS. Using this setup, the reactivity of 1.5 wt% Pt/CeO2 catalyst was studied with 100 ms resolution during periodic cycling in CO- and oxygen-containing atmospheres in a plug-flow reactor. Measurements were performed at the Pt L3- and Ce L3-edges. The reactivity of platinum and cerium demonstrated a strong correlation. The oxidation of the catalyst starts on the ceria support helping the oxidation of platinum nanoparticles. The new time-resolved XAS setup can be applied to various systems, capable of reproducible cycling between different states triggered by gas atmosphere, light, temperature, etc. It opens up new perspectives for mechanistic studies on automotive catalysts, selective oxidation catalysts and photocatalysts.

Synthesis of Iron Oxide Nanoclusters by Thermal Decomposition.

Herein, we report a novel one-step solvothermal synthesis of magnetite nanoclusters (MNCs). In this report, we discuss the synthesis, structure, and properties of MNCs and contrast enhancement in T2-weighted MR images using magnetite nanoclusters. The effect of different organic acids, used as surfactants, on the size and shape of MNCs was investigated. The structure and properties of samples were determined by magnetic measurements, TGA, TEM, HRTEM, XRD, FTIR, and MRI. Magnetic measurements show that obtained MNCs have relatively high saturation magnetization values (65.1-81.5 emu/g) and dependence of the coercive force on the average size of MNCs was established. MNCs were transferred into an aqueous medium by Pluronic F-127, and T2-relaxivity values were determined. T2-Weighted MR phantom images clearly demonstrated that such magnetite nanoclusters can be used as contrast agents for MRI.

Time-resolved operando studies of carbon supported Pd nanoparticles under hydrogenation reactions by X-ray diffraction and absorption.

The formation of palladium hydride and carbide phases in palladium-based catalysts is a critical process that changes the catalytic performance and selectivity of the catalysts in important industrial reactions, such as the selective hydrogenation of alkynes or alkadienes. We present a comprehensive study of a 5 wt% carbon supported Pd nanoparticle (NP) catalyst in various environments by using in situ and operando X-ray absorption spectroscopy and diffraction, to determine the structure and evolution of palladium hydride and carbide phases, and their distribution throughout the NPs. We demonstrate how the simultaneous analysis of extended X-ray absorption fine structure (EXAFS) spectra and X-ray powder diffraction (XRPD) patterns allows discrimination between the inner "core" and outer "shell" regions of the NP during hydride phase formation at different temperatures and under different hydrogen pressures, indicating that the amount of hydrogen in the shell region of the NP is lower than that in the core. For palladium carbide, advanced analysis of X-ray absorption near-edge structure (XANES) spectra allows the detection of Pd-C bonds with carbon-containing molecules adsorbed at the surface of the NPs. In addition, H/Pd and C/Pd stoichiometries of PdHx and PdCy phases were obtained by using theoretical modelling and fitting of XANES spectra. Finally, the collection of operando time-resolved XRPD patterns (with a time resolution of 5 s) allowed the detection, during the ethylene hydrogenation reaction, of periodic oscillations in the NPs core lattice parameter, which were in phase with the MS signal of ethane (product) and in antiphase with the MS signal of H2 (reactant), highlighting an interesting direct structure-reactivity relationship. The presented studies show how a careful combination of X-ray absorption and diffraction can differentiate the structure of the core, shell and surface of the palladium NPs under working conditions and prove their relevant roles in catalysis.

Operando study of palladium nanoparticles inside UiO-67 MOF for catalytic hydrogenation of hydrocarbons.

Functionalization of metal-organic frameworks with metal nanoparticles (NPs) is a promising way for producing advanced materials for catalytic applications. We present the synthesis and in situ characterization of palladium NPs encapsulated inside a functionalized UiO-67 metal-organic framework. The initial structure was synthesized with 10% of PdCl2bpydc moieties with grafted Pd ions replacing standard 4,4'-biphenyldicarboxylate linkers. This material exhibits the same high crystallinity and thermal stability of standard UiO-67. Formation of palladium NPs was initiated by sample activation in hydrogen and monitored by in situ X-ray powder diffraction and X-ray absorption spectroscopy (XAS). The reduction of PdII ions to Pd0 occurs above 200 °C in 6% H2/He flow. The formed palladium NPs have an average size of 2.1 nm as limited by the cavities of UiO-67 structure. The resulting material showed high activity towards ethylene hydrogenation. Under reaction conditions, palladium was found to form a carbide structure indicated by operando XAS, while formation of ethane was monitored by mass spectroscopy and infra-red spectroscopy.

Individual expression features of GPX2, NQO1 and SQSTM1 transcript variants induced by hydrogen peroxide treatment in HeLa cells.

Pathway activity assessment-based approaches are becoming highly influential in various fields of biology and medicine. However, these approaches mostly rely on analysis of mRNA expression, and total mRNA from a given locus is measured in the majority of cases. Notably, a significant portion of protein-coding genes produces more than one transcript. This biological fact is responsible for significant noise when changes in total mRNA transcription of a single gene are analyzed. The NFE2L2/AP-1 pathway is an attractive target for biomedical applications. To date, there is a lack of data regarding the agreement in expression of even classical target genes of this pathway. In the present paper we analyzed whether transcript variants of GPX2, NQO1 and SQSTM1 were characterized by individual features of expression when HeLa cells were exposed to pro-oxidative stimulation with hydrogen peroxide. We found that all the transcripts (10 in total) appeared to be significantly individually regulated under the conditions tested. We conclude that individual transcripts, rather than total mRNA, are best markers of pathway activation. We also discuss here some biological roles of individual transcript regulation.

Covalent functionalization of HiPco single-walled carbon nanotubes: differences in the oxidizing action of H2 SO4 and HNO3 during a soft oxidation process.

The results of a study on the evolution of HiPco single-walled carbon nanotubes during the oxidizing action of H2 SO4 and HNO3 are presented. The process conditions used have been chosen so as to avoid any significant damage to the nanotube structure. The type and level of functionalization, the location of the grafted functions on the surface of the nanotube and the changes in morphological characteristics of the samples were examined by using a wide and complementary range of analytical techniques. We propose an explanation for the differences in the oxidizing action of sulfuric and nitric acids. The combined results allow us to suggest possible reaction mechanisms that occur on the surface of the nanotube.

Machine Learning Meets Cancer.

The role of machine learning (a part of artificial intelligence-AI) in the diagnosis and treatment of various types of oncology is steadily increasing. It is expected that the use of AI in oncology will speed up both diagnostic and treatment planning processes. This review describes recent applications of machine learning in oncology, including medical image analysis, treatment planning, patient survival prognosis, and the synthesis of drugs at the point of care. The fast and reliable analysis of medical images is of great importance in the case of fast-flowing forms of cancer. The introduction of ML for the analysis of constantly growing volumes of big data makes it possible to improve the quality of prescribed treatment and patient care. Thus, ML is expected to become an essential technology for medical specialists. The ML model has already improved prognostic prediction for patients compared to traditional staging algorithms. The direct synthesis of the necessary medical substances (small molecule mixtures) at the point of care could also seriously benefit from the application of ML. We further review the main trends in the use of artificial intelligence-based technologies in modern oncology. This review demonstrates the future prospects of using ML tools to make progress in cancer research, as well as in other areas of medicine. Despite growing interest in the use of modern computer technologies in medical practice, a number of unresolved ethical and legal problems remain. In this review, we also discuss the most relevant issues among them.

Optimal Dynamic Regimes for CO Oxidation Discovered by Reinforcement Learning.

Metal nanoparticles are widely used as heterogeneous catalysts to activate adsorbed molecules and reduce the energy barrier of the reaction. Reaction product yield depends on the interplay between elementary processes: adsorption, activation, desorption, and reaction. These processes, in turn, depend on the inlet gas composition, temperature, and pressure. At a steady state, the active surface sites may be inaccessible due to adsorbed reagents. Periodic regime may thus improve the yield, but the appropriate period and waveform are not known in advance. Dynamic control should account for surface and atmospheric modifications and adjust reaction parameters according to the current state of the system and its history. In this work, we applied a reinforcement learning algorithm to control CO oxidation on a palladium catalyst. The policy gradient algorithm was trained in the theoretical environment, parametrized from experimental data. The algorithm learned to maximize the CO2 formation rate based on CO and O2 partial pressures for several successive time steps. Within a unified approach, we found optimal stationary, periodic, and nonperiodic regimes for different problem formulations and gained insight into why the dynamic regime can be preferential. In general, this work contributes to the task of popularizing the reinforcement learning approach in the field of catalytic science.

High energy resolution core-level X-ray spectroscopy for electronic and structural characterization of osmium compounds.

A comprehensive study of the bulk solid OsCl3 and the molecular ion [Os(bpy)2(CO)Cl](+) is presented illustrating the application of RIXS and HERFD XANES spectroscopies to the investigation of both bulk materials and molecular complexes. In order to analyze the experimental results, DFT simulations were performed taking into account spin-orbit interaction. Calculations for both compounds resulted in good agreement with the experimental RIXS and HERFD XANES data, shedding light on the details of their local atomic and electronic structure. In particular, the spatial distribution of molecular orbitals was obtained, which allowed the determination of the origin of the absorption peaks. It was shown that for materials containing heavy atoms, only the application of advanced RIXS and HERFD XANES spectroscopies makes it possible to extract the information on local atomic and electronic structure details from XANES data.