Tensile Deformation and Fracture Behavior of API-5L X70 Line Pipe Steel

Thermo-mechanical controlled processing (TMCP) is employed to obtain the required level of mechanical properties of contemporary HSLA steel plates utilized for gas and oil pipeline production. The strength and crack resistance of pipeline steels are mainly determined by its microstructure and crystallographic texture. In this study, the influence of the structural and textural states of industrially produced API-5L X70-X80 pipeline steels on tensile mechanical properties was analyzed. TMCP routes with different hot rolling temperatures and cooling rates were employed. The texture of steel was assessed using the Taylor factor, which was calculated based on electron backscatter diffraction (EBSD). The decrease in rolling temperature resulted in the sharper texture characterized by {001} planes banding (cleavage planes in the bcc lattice) parallel to rolling direction. The tensile deformation behavior at the stage of necking was determined by the crystallographic and morphological texture of the material and demonstrated significant anisotropy. Rupture of all investigated samples was accompanied by the development of splitting on the fracture surface. The splitting was localized in the rolling plane similar to the splitting in standard Charpy tests of pipeline steels.     

Structural Analysis of Lignin-Based Furan Resin

The global “carbon emission peak” and “carbon neutrality” strategic goals promote us to replace current petroleum-based resin products with biomass-based resins. The use of technical lignins and hemicellulose-derived furfuryl alcohol in the production of biomass-based resins are among the most promising ways. Deep understanding of the resulting resin structure is a prerequisite for the optimization of biomass-based resins. Herein, a semiquantitative 2D HSQC NMR technique supplemented by the quantitative ³¹P NMR and methoxyl group wet chemistry analysis were employed for the structural elucidation of softwood kraft lignin-based furfuryl alcohol resin (LFA). The LFA was fractionated into water-insoluble (LFA-I) and soluble (LFA-S) parts. The analysis of methoxyl groups showed that the amount of lignin was 85 wt% and 44 wt% in LFA-I and LFA-S fractions, respectively. The HSQC spectra revealed the high diversity of linkages formed between lignin and poly FA (pFA). The HSQC and ³¹P results indicated the formation of new condensed structures, particularly at the 5-position of the aromatic ring. Esterification reactions between carboxyl groups of lignin and hydroxyl groups of pFA could also occur. Furthermore, it was suggested that lignin phenolic hydroxyl oxygen could attack an opened furan ring to form several aryl ethers structures. Therefore, the LFA resin was produced through crosslinking between lignin fragments and pFA chains.     

Brief Report: RedChIP identifies noncoding RNAs associated with genomic sites occupied by Polycomb and CTCF proteins

Nuclear noncoding RNAs (ncRNAs) are key regulators of gene expression and chromatin organization. The progress in studying nuclear ncRNAs depends on the ability to identify the genome-wide spectrum of contacts of ncRNAs with chromatin. To address this question, a panel of RNA–DNA proximity ligation techniques has been developed. However, neither of these techniques examines proteins involved in RNA–chromatin interactions. Here, we introduce RedChIP, a technique combining RNA–DNA proximity ligation and chromatin immunoprecipitation for identifying RNA–chromatin interactions mediated by a particular protein. Using antibodies against architectural protein CTCF and the EZH2 subunit of the Polycomb repressive complex 2, we identify a spectrum of cis- and trans-acting ncRNAs enriched at Polycomb- and CTCF-binding sites in human cells, which may be involved in Polycomb-mediated gene repression and CTCF-dependent chromatin looping. By providing a protein-centric view of RNA–DNA interactions, RedChIP represents an important tool for studies of nuclear ncRNAs.     

Supramolecular D⋯A-layered structures based on germanium complexes with 2,3-dihydroxynaphthalene and N,N′-bidentate ligands

The concept of using redox-active ligands, which has become extremely widespread in organometallic chemistry, is often considered from ‘their effect on the metal center properties’ point of view and ‘how to modify the ligands’. In this paper, we present the reverse side of this effective approach – a dramatic change of redox properties of ligands under the influence of a redox-inert metal. Germanium derivatives based on 2,3-dihydroxynaphthalene (1) and N,N′-bidentate ligands, namely 2,2′-bipyridine (2) and 1,10-phenanthroline (3), were obtained and characterized by CV, UV-vis spectroscopy, DFT calculations and in the case of 3 X-ray diffraction. It was shown that the HOMO of the complexes is almost completely located on the naphthalene fragment while the LUMO is on the N,N-ligands. At the same time, there are no boundary molecular orbitals on the germanium atom, but it forms the axial part of the molecule holding two opposite motifs together. Moreover, it sharply affects the level of HOMO and LUMO. Derivatives 2 and 3 are more easily oxidized compared to 2,3-dihydroxynaphthalene by 0.31–0.34 V (7–8 kcal mol⁻¹) and are more easily reduced compared to N,N-donors by 1.08–1.15 V (25–26.5 kcal mol⁻¹). All this together makes it possible to form a system with a narrow HOMO/LUMO gap (∼2 eV). The crystal structure of 3 consists of alternating monomolecular easily oxidizing and easily reducing layers formed due to intermolecular interactions, in particular π-stacking. In addition, in contrast to 1 that starts to decompose noticeably at the temperatures from 200 °C, 2 and 3 have an extremely high thermal stability. They remain stable with no signs of decomposition and melting up to 400 °С. We believe that this approach to the formation of the supramolecular structure may present prospects for obtaining new functional materials.

The concept of using redox-active ligands is often considered from ‘their effect on the metal center properties’ point of view. We present the reverse side of this approach – change of redox properties of ligands under the influence of metal.     

One-step synthesis,characterization and properties of novel hybrid electromagnetic nanomaterials based on polydiphenylamine and Co–Fe particles in the absence and presence of single-walled carbon nanotubes

A one-step preparation method for hybrid electromagnetic nanomaterials based on polydiphenylamine (PDPA) and bimetallic Co–Fe particles in the absence and presence of single-walled carbon nanotubes (SWCNT) was proposed. During IR heating of PDPA in the presence of Co(ii) and Fe(iii) salts in an inert atmosphere at T = 450–600 °C, the polycondensation of diphenylamine (DPA) oligomers and dehydrogenation of phenyleneamine units of the polymer with the formation of C N bonds and reduction of metals by evolved hydrogen with the formation of bimetallic Co–Fe particles dispersed in a polymer matrix occur simultaneously. When carbon nanotubes are introduced into the reaction system, a nanocomposite material is formed, in which bimetallic Co–Fe particles immobilized on SWCNT are distributed in the matrix of the polymer. According to XRD data, reflection peaks of bimetallic Co–Fe particles at diffraction scattering angles 2θ = 69.04° and 106.5° correspond to a solid solution based on the fcc-Co crystal lattice. According to SEM and TEM data, a mixture of particles with sizes of 8–30 nm and 400–800 nm (Co–Fe/PDPA) and 23–50 nm and 400–1100 nm (Co–Fe/SWCNT/PDPA) is formed in the nanocomposites. The obtained multifunctional Co–Fe/PDPA and Co–Fe/SWCNT/PDPA nanomaterials demonstrate good thermal, electrical and magnetic properties. The saturation magnetization of the nanomaterials is M_S = 14.99–31.32 emu g⁻¹ (Co–Fe/PDPA) and M_S = 29.48–48.84 emu g⁻¹ (Co–Fe/SWCNT/PDPA). The electrical conductivity of the nanomaterials reaches 3.5 × 10⁻³ S cm⁻¹ (Co–Fe/PDPA) and 1.3 S cm⁻¹ (Co–Fe/SWCNT/PDPA). In an inert medium, at 1000 °C the residue is 71–77%.

In a self-organizing system within one stage under IR heating conditions, hybrid nanomaterials are formed with a structure that contains bimetallic Co–Fe particles, free or immobilized on the SWCNT surface, dispersed in the polymer PDPA matrix.     

Neurohumoral,cardiac and inflammatory markers in the evaluation of heart failure severity and progression

Heart failure is common in adult population,accounting for substantial morbidity and mortality worldwide.The main risk factors for heart failure are coronary artery disease,hypertension,obesity,diabetes mellitus,chronic pulmonary diseases,family history of cardiovascular diseases,cardiotoxic therapy.The main factor associated with poor outcome of these patients is constant progression of heart failure.In the current review we present evidence on the role of established and candidate neurohumoral biomarkers for heart failure progression management and diagnostics.A growing number of biomarkers have been proposed as potentially useful in heart failure patients,but not one of them still resembles the characteristics of the"ideal biomarker."A single marker will hardly perform well for screening,diagnostic,prognostic,and therapeutic management purposes.Moreover,the pathophysiological and clinical significance of biomarkers may depend on the presentation,stage,and severity of the disease.The authors cover main classification of heart failure phenotypes,based on the measurement of left ventricular ejection fraction,including heart failure with preserved ejection fraction,heart failure with reduced ejection fraction,and the recently proposed category heart failure with mid-range ejection fraction.One could envisage specific sets of biomarker with different performances in heart failure progression with different left ventricular ejection fraction especially as concerns prediction of the future course of the disease and of left ventricular adverse/reverse remodeling.This article is intended to provide an overview of basic and additional mechanisms of heart failure progression will contribute to a more comprehensive knowledge of the disease pathogenesis.     

Electrophysiology of statistical learning: Exploring the online learning process and offline learning product

A continuous stream of syllables is segmented into discrete constituents based on the transitional probabilities (TPs) between adjacent syllables by means of statistical learning. However, we still do not know whether people attend to high TPs between frequently co‐occurring syllables and cluster them together as parts of the discrete constituents or attend to low TPs aligned with the edges between the constituents and extract them as whole units. Earlier studies on TP‐based segmentation also have not distinguished between the segmentation process (how people segment continuous speech) and the learning product (what is learnt by means of statistical learning mechanisms). In the current study, we explored the learning outcome separately from the learning process, focusing on three possible learning products: holistic constituents that are retrieved from memory during the recognition test, clusters of frequently co‐occurring syllables, or a set of statistical regularities which can be used to reconstruct legitimate candidates for discrete constituents during the recognition test. Our data suggest that people employ boundary‐finding mechanisms during online segmentation by attending to low inter‐syllabic TPs during familiarization and also identify potential candidates for discrete constituents based on their statistical congruency with rules extracted during the learning process. Memory representations of recurrent constituents embedded in the continuous speech stream during familiarization facilitate subsequent recognition of these discrete constituents.     

The role of polo-like kinase 3 in the response of BRAF-mutant cells to targeted anticancer therapies

The activation of oncogenic mitogen-activated protein kinase cascade via mutations in BRAF is often observed in human melanomas. Targeted inhibitors of BRAF (BRAFi), alone or as a part of a combination therapy, offer a significant benefit to such patients. Unfortunately, some cases are initially nonresponsive to these drugs, while others become refractory in the course of treatment, underscoring the need to understand and mitigate the underlying resistance mechanisms. We report that interference with polo-like kinase 3 (PLK3) reduces the tolerance of BRAF-mutant melanoma cells to BRAFi, while increased PLK3 expression has the opposite effect. Accordingly, PLK3 expression correlates with tolerance to BRAFi in a panel of BRAF-mutant cell lines and is elevated in a subset of recurring BRAFi-resistant melanomas. In PLK3-expressing cells, R406, a kinase inhibitor whose targets include PLK3, recapitulates the sensitizing effects of genetic PLK3 inhibitors. The findings support a role for PLK3 as a predictor of BRAFi efficacy and suggest suppression of PLK3 as a way to improve the efficacy of targeted therapy.     

Two-step nucleation of the Earth’s inner core

The Earth''s inner core started forming when molten iron cooled below the melting point. However, the nucleation mechanism, which is a necessary step of crystallization, has not been well understood. Recent studies have found that it requires an unrealistic degree of undercooling to nucleate the stable, hexagonal, close-packed (hcp) phase of iron that is unlikely to be reached under core conditions and age. This contradiction is referred to as the inner core nucleation paradox. Using a persistent embryo method and molecular dynamics simulations, we demonstrate that the metastable, body-centered, cubic (bcc) phase of iron has a much higher nucleation rate than does the hcp phase under inner core conditions. Thus, the bcc nucleation is likely to be the first step of inner core formation, instead of direct nucleation of the hcp phase. This mechanism reduces the required undercooling of iron nucleation, which provides a key factor in solving the inner core nucleation paradox. The two-step nucleation scenario of the inner core also opens an avenue for understanding the structure and anisotropy of the present inner core.

The core plays a key role in the Earth’s evolution. The present core contains two major parts, a solid inner core and a liquid outer core. Iron dominates both parts with a small amount of light elements (1). The solid core is generally believed to be hexagonal, close-packed (hcp) iron, while the possible existence of body-centered, cubic (bcc) iron has also been suggested (2–5). The growth of the solid inner core is believed to be the major driving force of the present geodynamo, providing the main power source for convection in the liquid core (6, 7). Despite its importance, the initial formation of the solid core, which directly relates to its thermal evolution and Earth’s history, is far from being completely understood (8–12). Most of Earth’s thermal history models assume that the inner core started to crystallize when molten iron cooled right below its melting temperature at the Earth’s center (7). However, in practice, nucleation does not happen at the melting point but requires some undercooling because of the formation of a solid–liquid interface (SLI) that accompanies it. While the bulk solid phase is thermodynamically favored, the SLI costs energy. These two factors lead to a nucleation barrier ΔG, which is described in classical nucleation theory (CNT) (13) asΔG=NΔμ+Aγ,[1]where N is the nucleus size, Δμ (<0) is the free energy difference between the bulk solid and liquid, γ (>0) is SLI free energy, and A is the SLI area. The liquid must be cooled sufficiently below the melting temperature to overcome the free-energy barrier during thermal fluctuations. After considering this mechanism, it was found that a very large undercooling of ∼1,000 K is required for the nucleation of hcp iron in the Earth’s core (14). However, considering the slow cooling rate of ∼100 K/Gyr throughout the core history (15), it is impossible to reach such a large degree of undercooling inside the Earth within the inner core’s age. This “inner core nucleation paradox,” recently described by Huguet et al. (14), strongly challenges the current understanding of the inner core formation process. While Huguet et al.’s argument relies on a few estimations of thermodynamic quantities, Davies et al. also confirmed the paradox with atomic-scale simulations (16). Even considering the effect of light elements on the nucleation process, it still requires 675 K undercooling to nucleate hcp iron, nearly impossible to reach in the Earth core (16).CNT was proposed more than a century ago, and its formalism is the most widely used to describe nucleation phenomena nowadays. The simplest scenario in CNT assumes a single-nucleation pathway where only the nucleus of the thermodynamically stable phase forms and grows toward the bulk phase. This was the situation considered in refs. 14 and 15), in which the authors assumed that the melt in the Earth’s core crystallized directly into the hcp phase. Recent studies have shown that nucleation can be a multistep process that includes multiple intermediate stages and phases (17–19). While the CNT concept of nucleus formation is still valid under these situations, phase competition must be considered (18, 19). Therefore, instead of the single-pathway scenario, we can consider a complex process in which nucleation is facilitated by forming an intermediate phase with a high-nucleation rate. For example, it has been observed that the bcc phase can nucleate before the face-centered, cubic (fcc) or hcp phases in a few alloys in which the fcc/hcp phase is the most stable one (20–24). Could the bcc phase also facilitate hcp iron nucleation and relate to the inner core nucleation paradox? Making a quantitative prediction on such complex nucleation processes is a challenging problem. In addition to the extreme conditions in the core, nucleation involves microscopic-length scales that are extremely hard to probe in real time, even with state-of-the-art measurements (25). Hence, it requires computer simulations, particularly large-scale molecular dynamics (MD), to reproduce the temporal evolution of the liquid into the crystal (26). Unfortunately, nucleation under Earth’s core conditions is a rare event that occurs on the geological time scale, far beyond the reach of conventional MD simulations. Besides, large-scale MD simulations require semiempirical potentials to describe atomic interactions, and the outcome may depend heavily on the potential’s quality (27). In this work, we assess the inner core nucleation process with the account of competition between bcc and hcp phases during the nucleation process using the persistent embryo method (PEM) (28) to overcome the significant time limitation in conventional MD simulation of nucleation.     

Photoluminescence and Energy Transfer in Double- and Triple-Lanthanide-Doped YVO4 Nanoparticles

Optical materials doped with several lanthanides are unique in their properties and are widely used in various fields of science and technology. The study of these systems provides solutions for noncontact thermometry, bioimaging, sensing technology, and others. In this paper, we report on the demonstration of YVO₄ nanoparticles doped with one, two, and three different rare earth ions (Tm³⁺, Er³⁺, and Nd³⁺). We discuss the morphology, structural properties, and luminescence behavior of particles. Luminescence decay kinetics reveal the energy transfer efficiency (up to 78%) for different ions under the selective excitation of individual ions. Thus, we found that the energy transition from Tm³⁺ is more favorable than from Er³⁺ while we did not observe any significant energy rearrangement in the samples under the excitation of Nd³⁺. The observed strong variation of REI lifetimes makes the suggested nanoparticles promising for luminescent labeling, anticounterfeiting, development of data storage systems, etc.