Transmission Electron Microscopy Technologies Research Articles

Using In-situ Transmission Electron Microscopy to Study Strong Metal-Support Interactions in Heterogeneous Catalysis.

Precisely controlling the microstructure of supported metal catalysts and regulating metal-support interactions at the atomic level are essential for achieving highly efficient heterogeneous catalysts. Strong metal-support interaction (SMSI) not only stabilizes metal nanoparticles and improves their resistance to sintering but also modulates the electrical interaction between metal species and the support, optimizing the catalytic activity and selectivity. Therefore, understating the formation mechanism of SMSI and its dynamic evolution during the chemical reaction at the atomic scale is crucial for guiding the structural design and performance optimization of supported metal catalysts. Recent advancements in in-situ transmission electron microscopy (TEM) have shed new light on these complex phenomena, providing deeper insights into the SMSI dynamics. Here, the research progress of in-situ TEM investigation on SMSI in heterogeneous catalysis is systematically reviewed, focusing on the formation dynamics, structural evolution during the catalytic reactions, and regulation methods of SMSI. The significant advantages of in-situ TEM technologies for SMSI research are also highlighted. Moreover, the challenges and probable development paths of in-situ TEM studies on the SMSI are also provided.

Revealing microscopic dynamics: in situ liquid-phase TEM for live observations of soft materials and quantitative analysis via deep learning.

In various domains spanning materials synthesis, chemical catalysis, life sciences, and energy materials, in situ transmission electron microscopy (TEM) methods exert a profound influence. These methodologies enable the real-time observation and manipulation of gas-phase and liquid-phase reactions at the nanoscale, facilitating the exploration of pivotal reaction mechanisms. Fundamental research areas like crystal nucleation, growth, etching, and self-assembly have greatly benefited from these techniques. Additionally, their applications extend across diverse fields such as catalysis, batteries, bioimaging, and drug delivery kinetics. However, the intricate nature of 'soft matter' presents a challenge due to the unique molecular properties and dynamic behavior of these substances that remain insufficiently understood. Investigating soft matter within in situ liquid-phase TEM settings demands further exploration and advancement compared to other research domains. This research harnesses the potential of in situ liquid-phase TEM technology while integrating deep learning methodologies to comprehensively analyze the quantitative aspects of soft matter dynamics. This study centers on diverse phenomena, encompassing surfactant molecule nucleation, block copolymer behavior, confinement-driven self-assembly, and drying processes. Furthermore, deep learning techniques are employed to precisely analyze Ostwald ripening and digestive ripening dynamics. The outcomes of this study not only deepen the understanding of soft matter at its fundamental level but also serve as a pivotal foundation for developing innovative functional materials and cutting-edge devices.

Detection of ribophagy in yeast and mammals.

Ribophagy, the cellular process wherein ribosomes are selectively self-digested through autophagy, plays a pivotal role in maintaining ribosome turnover. Understanding the molecular regulatory mechanisms governing ribophagy is pivotal to uncover its significance. Consequently, the establishment of methods for detecting ribophagy becomes important. In this protocol, we have optimized, enriched, and advanced existing ribophagy detection techniques, including immunoblotting, fluorescence microscopy, and transmission electron microscopy (TEM), to precisely monitor and quantify ribophagic events. Particularly noteworthy is the introduction of TEM technology for yeast ribophagy detection. In summary, the delineated methods are applicable for detecting ribophagy in both yeast and mammals, laying a solid foundation for further exploring the physiological importance of ribophagy and its potential implications in diverse cellular environments.

Magnetic biochar-supported layered double hydroxide for simultaneous remediation of As and Cd in soil: Effectiveness, retention durability, and insight into a new immobilization mechanism

Immobilization/stabilization is a common technique for remediating As and Cd-contaminated soil. However, the effectiveness of employed stabilizer plays a crucial role in determining the fate of these contaminants. This study investigated the effectiveness and durability of a magnetic biochar-supported Ca–Mg–Al layered double hydroxide composite (FLBC) and its components in simultaneous remediation of As and Cd in Phaeozem (BS) and Krasnozem soils (RS). Results demonstrated that 5 wt% FLBC amendment immobilized >85% of As and Cd and converted them into immobile fractions even in a reduction environment. Moreover, FLBC treatment effectively resisted leaching of As and Cd by > 70% under acidic rainwater filtration, thus displaying excellent retention durability. The new immobilization mechanisms were proved using transmission electron microscope technology, where layered double hydroxide (LDH) acted as a nano-bridge to bind FLBC and soil colloids ensuring FLBC stability and synergistic immobilization. During this process, X-ray photoelectron analysis demonstrated the re-oxidation of As(III) to As(V) driven by ferric reduction that resulted in the formation of multiple stable species on the soil surface via the confirmation of X-ray absorption near fine structure and extended X-ray absorption fine structure. This species included Ca/Fe/Cd–As(V) and γ-Cd(OH)2 co-precipitation, as well as As(V)–O–Fe(III)/Ca and As–Fe tridentate-hexanuclear corner-sharing complexes. Furthermore, FLBC amendment favored the immobilization of As and Cd in RS soil compared to BS soil due to a weaker reduction potential and an increased participation of metal-(hydr)oxides for As and Cd complexation. This study provides valuable references for predicting the impact of LDH-coupled magnetic biochar technology on the fate of As and Cd in actual soil environments.

Atomic-Scale Imaging of Organic-Inorganic Hybrid Perovskite Using Transmission Electron Microscope

Transmission electron microscope (TEM) is thought as one powerful tool to imaging the atomic-level structure of organic inorganic hybrid perovskite (OIHP) materials, which provides valuable and essential guidance toward high performance OIHP-related devices. However, these OIHPs exhibit poor electron beam stability, severely limiting their practical applications in TEM. Here in this article, the application of TEM to obtain atomic-scale image of OIHPs, main obstacles in identifying the degradation product and future prospects of TEM in the characterization of OIHP materials are reviewed and presented. Three potential strategies (sample protection, low temperature technology, and low-dose technologies) are also proposed to overcome the current drawback of TEM technology.

Imaging biological macromolecules in thick specimens: The role of inelastic scattering in cryoEM

We investigate potential improvements in using electron cryomicroscopy to image thick specimens with high-resolution phase contrast imaging. In particular, using model experiments, electron scattering theory, Monte Carlo and multislice simulations, we determine the potential for improving electron cryomicrographs of proteins within a cell using chromatic aberration (Cc) correction. We show that inelastically scattered electrons lose a quantifiable amount of spatial coherence as they transit the specimen, yet can be used to enhance the signal from thick biological specimens (in the 1000 to 5000 Å range) provided they are imaged close to focus with an achromatic lens. This loss of information quantified here, which we call “specimen induced decoherence”, is a fundamental limit on imaging biological molecules in situ. We further show that with foreseeable advances in transmission electron microscope technology, it should be possible to directly locate and uniquely identify sub-100 kDa proteins without the need for labels, in a vitrified specimen taken from a cell.

In Situ TEM Technique Revealing the Deactivation Mechanism of Bimetallic Pd-Ag Nanoparticles in Hydrogen Sensors.

Bimetallic Pd-Ag alloy nanoparticles exhibit satisfactory H2-sensing improvements and show application potential for H2 sensor construction. However, the long-term stability of the H2 sensor with Pd-Ag nanoparticles as the catalyst is found to dramatically decrease during operation. Herein, gas-cell in situ transmission electron microscopy (TEM) is used to investigate the failure mechanisms of Pd-Ag nanoparticles under operation conditions. Based on the in situ TEM results, the Pd-Ag nanoparticles have two failure mechanisms: particles coalescence at 300 °C and phase segregation at 500 °C. Guided by the failure mechanisms, the H2 sensor is comprehensively optimized based on the working temperature and the amount of Pd-Ag alloy nanoparticles. The optimized sensor exhibits satisfactory H2-sensing properties, and the response decline of the sensor after 1 month is negligible. The revealing of the failure mechanisms with in situ TEM technology provides a valuable route for developing gas sensors with high long-term stability.

Review of electrical stimulus methods of in situ transmission electron microscope to study resistive random access memory.

Resistive random access memory (RRAM) devices have been demonstrated to be a promising solution for the implementation of a neuromorphic system with high-density synapses due to the simple device structure, nanoscale dimension, high switching speed, and low power consumption. Various electrical stimuli applied to RRAM devices could cause various working modes of the bionic synapses. The application of RRAM devices needs to understand the micromechanism of the resistive switching process, which is inseparable from advanced characterization techniques. In situ transmission electron microscopy (TEM) with high-resolution imaging and versatile external fields plays an important role in the static characterization and dynamic manipulation of nanoscale devices. Focused on in situ TEM techniques, this review article introduces in situ TEM setups and the corresponding sample fabrication process for RRAM research. Then, the electrical stimulating methodologies including pulse and direct current voltage applied to RRAM are introduced, followed by the summary of electron holography to characterize the electrical potential distribution. By applying various electrical stimuli to the RRAM samples, the working mode of bionic synapses could be changed according to the requirement. Finally, the outlook of the RRAM study with in situ TEM is proposed. This review demonstrates the electrical stimulus capability of in situ TEM to understand the physical mechanism of various types of RRAM devices.

Transmission Electron Microscopic Methods for Plant Virology.

Transmission electron microscopy (TEM) is an important tool for observing the ultrastructure of plant virions and their host cells. The two main applicable TEM technologies used in plant virology are negative staining and ultrathin section. Negative staining is mainly used to observe the high-resolution structure of virus particles under a transmission electron microscope. Sample preparation for negative staining is convenient and fast, making it suitable for studying the virions in crude sap or purified solution. A modification of negative staining, by combining immunological reaction, named as technique of immuno-negative staining, is used to enrich or identify viruses. Ultrathin section is used for ultrastructural cytopathological studies in the virus-infected host cells, including the morphology of virus particles, the structure of viral induced inclusion bodies, the subcellular distribution of virions and the structural alteration of the host cell induced by viral infection. Such information is valuable to analyze the behavior of virus in replication, assembly, and intercellular transportation, and thus to understand the viral infection cycle. The present chapter describes the operation details of negative staining and ultrathin section TEM.

Evaluation of the sole and integrated application of nano-graphene oxide, zeolite, and chitosan on gas exchanges and silymarin content of milk thistle (Silybum marianum L.) under salinity stress

Identifying environmental factors, plant characteristics, and agronomic activities plays an essential role in medicinal plant production. Milk thistle (Silybum marianum L.) is a well-known medicinal plant with extensive use in diverse liver diseases and is economically a significant crop. This research was conducted to evaluate the effect of the sole and integrated applications of graphene oxide (GO), zeolite, and chitosan as modifying materials on gas exchange and the secondary metabolites of milk thistle under severe salinity stress. Seven sole and integrated combinations of nano-materials comprised of T1, T2, T3, T4, T5, T6, T7, and control (T8, no nano-materials application) and two levels of saline water (12 ds/m) and tap water (control, 0.8 ds/m) were applied to the soil of experimental plots based on a factorial design with three replications. The results showed that the highest photosynthesis rate was obtained with T7 treatment for both water treatments. The highest plant silymarin concentration was obtained from the T6 treatment under both saline and tap water conditions. This treatment increased the silymarin concentration by 15.9% compared to the T8. The highest plant silymarin yield (180 mg per plant) was recorded for the T7 under tap water (control) condition, and 130.3 mg/plant for T6 under salinity stress, respectively. The Transmission Electron Microscope technology indicated that GO at low concentration (0.01%) could be safely used to enhance milk thistle germination and growth under severe salinity stress conditions

A revew of in situ transmission electron microscopy study on the switching mechanism and packaging reliability in non-volatile memory

Non-volatile memory (NVM) devices with non-volatility and low power consumption properties are important in the data storage field. The switching mechanism and packaging reliability issues in NVMs are of great research interest. The switching process in NVM devices accompanied by the evolution of microstructure and composition is fast and subtle. Transmission electron microscopy (TEM) with high spatial resolution and versatile external fields is widely used in analyzing the evolution of morphology, structures and chemical compositions at atomic scale. The various external stimuli, such as thermal, electrical, mechanical, optical and magnetic fields, provide a platform to probe and engineer NVM devices inside TEM in real-time. Such advanced technologies make it possible for an in situ and interactive manipulation of NVM devices without sacrificing the resolution. This technology facilitates the exploration of the intrinsic structure-switching mechanism of NVMs and the reliability issues in the memory package. In this review, the evolution of the functional layers in NVM devices characterized by the advanced in situ TEM technology is introduced, with intermetallic compounds forming and degradation process investigated. The principles and challenges of TEM technology on NVM device study are also discussed.

Microstructure and nanomechanical behavior of friction stir welded joint of 7055 aluminum alloy

In this paper, microstructure characterization of friction stir welding (FSW) joint of 7055-T6 aluminum alloy was performed via scanning electron microscope, electron backscatter diffraction, and transmission electron microscope technology. The nanomechanical behavior of FSW joint was systematically studied using nanoindentation technique. The relationship between microstructure and nanomechanical behavior was established and the nano-hardness and microhardness were analyzed. The results show that FSW led to grain refinement of aluminum alloy and continuous dynamic recrystallization and geometric dynamic recrystallization were the primary mechanisms of grain refinement. The precipitated phase dissolved and coarsened during FSW, which led to a decrease in the microhardness of the joint. The nano-hardness of each zone of the joint displayed indentation size effect. The creep behavior at room temperature conformed to the Voigt model, and dislocation glide was the primary creep mechanism. The stir zone (SZ) and thermo-mechanically affected zone (TMAZ) had high nano-hardness and elastic modulus, while TMAZ and heat-affected zone (HAZ) had high creep resistance at room temperature. The nanomechanical behavior was mainly affected by precipitation in the grain interior.

Insights into the Structure and Dynamics of Metal-Organic Frameworks via Transmission Electron Microscopy.

Metal-organic frameworks (MOFs) are hybrid materials composed of metal ions and organic linkers featuring high porosity, crystallinity, and chemical tunability at multiple length scales. A recent advancement in transmission electron microscopy (TEM) and its direct application to MOF structure-property relationships have changed how we consider rational MOF design and development. Herein, we provide a perspective on TEM studies of MOFs and highlight the utilization of state-of-the-art TEM technologies to explore dynamic MOF processes and host-guest interactions. Additionally, we provide thoughts on what the future holds for TEM in the study of MOFs.

Fabricated rGO-modified Ag2S nanoparticles/g-C3N4 nanosheets photocatalyst for enhancing photocatalytic activity

Photocatalytic technology provides a new strategy for the treatment of water pollution and energy crisis. Developing photocatalytic materials with high efficiency and stable visible light response has always been the direction of scientific researchers in the photocatalytic field. In this paper, we designed and prepared an efficient and stable rGO-modifited type-I Ag2S/g-C3N4 heterojunction photocatalyst (rGO/Ag2S/CN). The TEM (Transmission electron microscope) technology shows that the morphology of rGO/Ag2S/CN is a sandwich-like structure. UV–Vis DRS (UV–visible diffuse-reflectance spectrum) shows that the loading of Ag2S NPs and the modification of rGO effectively enhance the light response performance of nanocomposite materials in visible light. PL (Photoluminescence) and PEC (Photoelectrochemical) results prove that the photogenerated carriers transport and separation efficiency of rGO/Ag2S/CN have been improved. The photodegradation of RhB and the photoreduction of CO2 results confirmed that this ternary nanocomposite has great photocatalytic activity. The photodegradation efficiency of the RhB aqueous solution is about 98.5% after 30 min under the visible light irradiation. The photoreduction experiments showed that the yields of CO and CH4 are 178.05 μmol/g and 121.11 μmol/g, respectively after 8 h under the UV light irradiation. The results of cyclic photocatalytic experiments and the XRD pattern after those processes further revealed that the modification of rGO not only enhanced the photocatalytic performance of the nanocomposite photocatalyst, but also effectively improved the stability of Ag2S in the photocatalytic process. The possible photocatalytic reaction mechanisms were discussed in detail.

Growth and characterization of SnS2(1-x)Se2x alloys

In this study, SnS2(1-x)Se2x alloys layered crystals were grown by the chemical vapor transport method. The crystal structure characterization has been substantiated by X-ray diffraction (XRD) and transmission electron microscope technologies. From each sample’s XRD pattern, the peaks corresponds to (001), (002), (003), (004), and (005) which were found and used to determine the lattice constants. The band gap energies modulated from 2.28 eV (SnS2) to 1.23 eV (SnSe2) with the increasing content of Se, which were verified by piezoreflectance (PzR) spectra and absorption spectra. By PzR spectra and absorption spectra, the empirical relation between band gap energies and composition ratio, according to the extended Vegard’s law, has been predicted; accorded with a bowing parameter b of 0.56 and 0.54 eV, respectively.

Characterization of atomic defects on the photoluminescence in two‐dimensional materials using transmission electron microscope

AbstractTwo‐dimensional material (2D) that possesses atomic thin geometry and remarkable properties is a star material for the fundamental researches and advanced applications. Defects in 2D materials are critical and fundamental to understand the chemical, physical, and optical properties. Photoluminescence arises in 2D materials owing to various physical phenomena including activator/dopant‐induced luminescence and defect‐related emissions, and so forth. With the advanced transmission electron microscopy (TEM) technologies, such as aberration correction and low voltage technologies, the morphology, chemical compositions and electronic structures of defects in 2D material could be directly characterized at the atomic scale. In this review, we introduce the applications of state‐of‐the‐art TEM technologies on the studies of the role of atomic defects in the photoluminescence characteristics in 2D material. The challenges in spatial and time resolution are also discussed. It is proved that TEM is a powerful tool to pinpoint the relationship between the defects and the photoluminescence characteristics.

Equiaxed Solidification of 430 Ferritic Stainless Steel Nucleating on Core-Containing Ti

AbstractThe solidification structure of ferritic stainless steel can be refined by controlling the contents of Ti, O, and N in the liquid steel through the thermodynamic analysis and high-temperature experiment. It is found by the scanning electron microscopy technology, in which the composite core of Ti nitride-enwrapping Ti oxide can be formed in the solidification front, which promotes the nucleation of δ iron and refines the solidification structure. Meanwhile, the structure analysis of the composite core by the transmission electron microscope technology proves that the Ti oxide that exists in the centre of the composite core is Ti2O3 and the Ti nitride that exists in the outer layer of the composite core is TiN.

Development of in situ optical–electrical MEMS platform for semiconductor characterization

In situ transmission electron microscopy (TEM) technology has become one of the fastest growing areas in TEM research in recent years. This technique allows researchers to investigate the dynamic response of materials to external stimuli inside the microscope. Optoelectronic functional semiconducting materials play an irreplaceable role in several key fields such as clean energy, communications, and pollution disposal. The ability to observe the dynamic behavior of these materials under real working conditions using advanced TEM technologies would provide an in-depth understanding of their working mechanisms, enabling further improvement of their properties. In this work, we designed a microelectromechanical-system-chip-based system to illuminate a sample inside a transmission electron microscope. This system allows simultaneous in situ optical and electrical measurements, which are crucial for optoelectronic semiconductor characterization.

Cryo-electron microscopy of membrane proteins.

Membrane proteins represent a large proportion of the proteome, but have characteristics that are problematic for many methods in modern molecular biology (that have often been developed with soluble proteins in mind). For structural studies, low levels of expression and the presence of detergent have been thorns in the flesh of the membrane protein experimentalist. Here we discuss the use of cryo-electron microscopy in breakthrough studies of the structures of membrane proteins. This method can cope with relatively small quantities of sample and with the presence of detergent. Until recently, cryo-electron microscopy could not deliver high-resolution structures of membrane proteins, but recent developments in transmission electron microscope technology and in the image processing of single particles imaged in the microscope have revolutionized the field, allowing high resolution structures to be obtained. Here we focus on the specific issues surrounding the application of cryo-electron microscopy to the study of membrane proteins, especially in the choice of a system to keep the protein soluble.

Lipid accelerating the fibril of islet amyloid polypeptide aggravated the pancreatic islet injury in vitro and in vivo

BackgroundThe fibrillation of islet amyloid polypeptide (IAPP) triggered the amyloid deposition, then enhanced the loss of the pancreatic islet mass. However, it is not clear what factor is the determinant in development of the fibril formation. The aim of this study is to investigate the effects of lipid on IAPP fibril and its injury on pancreatic islet.MethodsThe fibril form of human IAPP (hIAPP) was tested using thioflavin-T fluorescence assay and transmission electron microscope technology after incubated with palmitate for 5 h at 25 °C. The cytotoxicity of fibril hIAPP was evaluated in INS-1 cells through analyzing the leakage of cell membrane and cell apoptosis. Type 2 diabetes mellitus (T2DM) animal model was induced with low dose streptozotocin combined the high-fat diet feeding for two months in rats. Plasma biochemistry parameters were measured before sacrificed. Pancreatic islet was isolated to evaluate their function.ResultsThe results showed that co-incubation of hIAPP and palmitate induced more fibril form. Fibril hIAPP induced cell lesions including cell membrane leakage and cell apoptosis accompanied insulin mRNA decrease in INS-1 cell lines. In vivo, Plasma glucose, triglyceride, rIAPP and insulin increased in T2DM rats compared with the control group. In addition, IAPP and insulin mRNA increased in pancreatic islet of T2DM rats. Furthermore, T2DM induced the reduction of insulin receptor expression and cleaved caspase-3 overexpression in pancreatic islet.ConclusionsResults in vivo and in vitro suggested that lipid and IAPP plays a synergistic effect on pancreatic islet cell damage, which implicated in enhancing the IAPP expression and accelerating the fibril formation of IAPP.