Mrs Bulletin最新文献

Abstract

We report atomistic mechanisms that directly correlate the time-dependent optical responses of bulk Ge₂₃Sb₇S₇₀ chalcogenide glasses to their metastable structural defects created and subsequently annihilated following gamma irradiation. These defects are characterized by an irradiation-induced increase in the concentration of edge-shared GeS_4/2 tetrahedra bonding units, which gradually decreases to a pre-irradiation level during recovery, thus illustrating the glass’ metastable behavior. This time-dependent structural change gives rise to the evolution of the glass’s mass density that correspondingly induces a change and subsequent relaxation of linear refractive index and bandgap energy. Concurrent with this evolution in linear optical properties, the glass’ nonlinear response is found to be unaffected, likely due to a counter effect associated with the glass network’s free electrons.

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Impact statement

Our work is the first study to employ a combined theoretical-experimental approach to the quantitative processing–structure–property relationship correlating the time-dependent structural and linear/nonlinear optical responses of chalcogenide Ge–Sb–S bulk glasses to their metastable topological coordination defects. These defects are created upon gamma-ray exposure and subsequently undergo relaxation at room temperature. The novelty of our study is that multifaceted aspects of such a key infrared chalcogenide glass, including optical, electronic, morphological, chemical, and microstructural properties, were monitored and cross-correlated as a function of time following gamma irradiation in order to identify origins behind the material system’s behavior as compared to base unirradiated material. This is, to our knowledge, the first-ever integrated approach (summarizing pre- and postexposure properties on the same samples) to the phenomenon. The behavior in metastable bulk chalcogenide glasses serves as a key cornerstone that will enable the material system to be deployed as robust, reversible radiation sensors in extreme environments such as space and ground-based radioactive facilities where gamma ray is characteristically abundant. Findings in our paper may shed light on the lingering question on the microscopic origin behind the self-healing process in chalcogenide glasses.

The world of biology created a wealth of complex materials intertwining order, disorder, and hierarchy. They are produced with minimal energy expenditures and display combinations of properties that surpass materials aimed to be perfectly ordered crystals or perfectly disordered glasses. De novo engineering of biomimetic materials with “impossible” combination of properties necessary for multiple technologies becomes possible considering complexity as a design parameter but this methodology lacks foundational principles. This article delineates the concept of complexity in the context of materials science. It examines the pathway to quantitative complexity–functionality relations and explores pragmatic approaches to scalable complex materials guided by discrete mathematics of nanoassemblies from imperfect components.

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Thanks to decades of tireless efforts, nanoparticle assemblies have reached an extremely high level of controllability, sophistication, and complexity, with new insights provided by integration with graph theory, cutting-edge characterization, and machine learning (ML)-based computation and modeling, as well as with ever-diversifying applications in energy, catalysis, biomedicine, optics, electronics, magnetics, organic biosynthesis, and quantum technology. Nanoparticle assemblies can be crystalline, known as superlattices or supracrystals. Their assembly entails a transition from disorder—dispersed nanoparticles—to order, which can be achieved through classical nucleation pathways or nonclassical pathways via prenucleation precursors or particle aggregation. The periodic lattices allow facile manipulations of electrons, phonons, photons, and even spins, leading to advanced device components and metamaterials. Meanwhile, aperiodic assemblies out of nanoparticles, such as gels, networks, and amorphous solids, also start to attract attention. Despite the loss of periodicity, symmetry-lowering or symmetry-breaking three-dimensional (3D) structures emerge with unique properties, such as chiroptical activity, topological mechanical strength, and quantum entanglement. Real-space imaging such as electron microscopy and x-ray-based tomography methods are utilized to characterize these complex structures, whereas mathematical tools such as graph theories are in need to describe such complex structures. This issue aims to provide a timely review of the efforts in this greatly broadened materials design space, including experiment, simulation, theory, and applications. Nine top experts (and their teams) from four countries deliver six articles summarizing fundamental mechanistic understandings of nanoparticle assemblies, highlighted with the developments of state-of-the-art in situ characterization tools and ML-assisted reverse engineering, and newly emergent applications of nanoarchitectures.

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Over the last several decades, colloidal nanoparticles have evolved into a prominent class of building blocks for materials design. Important advances include the synthesis of uniform nanoparticles with tailored compositions and properties, and the precision construction of intricate, higher-level structures from nanoparticles via self-assembly. Grasping the modern complexity of nanoparticles and their superstructures requires fundamental understandings of the processes of nanoparticle growth and self-assembly. In situ liquid phase transmission electron microscopy (TEM) has significantly advanced our understanding of these dynamic processes by allowing direct observation of how individual atoms and nanoparticles interact in real time, in their native phases. In this article, we highlight diverse nucleation and growth pathways of nanoparticles in solution that could be elucidated by the in situ liquid phase TEM. Furthermore, we showcase in situ liquid phase TEM studies of nanoparticle self-assembly pathways, highlighting the complex interplay among nanoparticles, ligands, and solvents. The mechanistic insights gained from in situ liquid phase TEM investigation could inform the design and synthesis of novel nanomaterials for various applications such as catalysis, energy conversion, and optoelectronic devices.

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The detrimental effects induced by hydrogen on different materials—including steels—are a well-known and studied phenomenon. In the last century, several research papers focusing on hydrogen damages were published, including investigations concerning the hydrogen impact on the crack growth rate in steels subjected to cyclic loading. However, the past studies focused on material behavior and the role of external factors (e.g., pressure, temperature, stress field, microstructure, inhibitors, etc.), while the consequences of these findings on safety procedures and guidelines remain unspoken. The present work aims at investigating how the manifestation of the hydrogen degradation effect on equipment subjected to fatigue loadings may reflect on conventional safety practices. More accurately, a review of the parameters governing pipeline fatigue life is undertaken to analyze how such variables may lead to undesirable events and ultimately promoting a loss of containment scenario. In this sense, this work appeals for an evolution of the existing inspection methodologies for components that may experience fatigue failures (i.e., piping and pipeline systems), since the time-dependency of the detrimental effects induced by hydrogen should be considered in the operations of accident prevention and risk mitigation. Hence, the development of a preventive inspection and maintenance strategy specifically conceived for hydrogen technologies is essential to avoid the loss prevention of hydrogen systems. This will not only contribute to a quicker and larger scale spread of a hydrogen infrastructure, but it will also foster the energy-transition challenge that our society is facing today.

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Serum microRNAs (miRs) have recently been proposed as potential cancer biomarkers for early detection. Thyroid hormones play a crucial role in human health, and their alterations are linked to a range of diseases, such as breast cancer. The relationship between NF-κβ, TNF-α, and non-coding RNAs is an urgent need for clinical trials. This study aimed to investigate serum expression folds of miR-155 and miR-375 and their correlations with NF-κβ and TNF-α in breast cancer patients. The current study was conducted on 183 unrelated female participants. Serum levels of free T3 and T4, as well as expression folds of miR-155 and miR-375, were significantly higher in patients with fibroadenoma and breast cancer, despite TSH being significantly lower. Additionally, the signaling of TNF-alpha and NF-κβ were found to be significantly upregulated in the serum of patients with breast cancer. Up-regulation of miR-155 and miR-375 expression may be diagnostic biomarkers of breast cancer, pointing to the role of NF-κβ and TNF-α expression in miR-155 and miR-375 expression as therapeutic targets of breast cancer in the future.