High-resolution Scanning Electron Microscopy Images Research Articles

Cross-scale backscattered-electron imaging and its application in revealing the microstructure-property relations

Scanning electron microscopy (SEM) has been widely utilized in the field of materials science due to its significant advantages, such as large depth of field, wide field of view, and excellent stereoscopic imaging. However, at high magnification, the limited imaging range in SEM cannot cover all the possible inhomogeneous microstructures. In this research, we propose a novel approach for generating high-resolution SEM images across multiple scales, enabling a single image to capture physical dimensions at the centimeter level while preserving submicron-level details. We adopted the SEM imaging on the AlCoCrFeNi2.1 eutectic high entropy alloy as an example. SEM videos and image stitching are combined to fulfill this goal, and the video-extracted low-definition images are clarified by a well-trained denoising model. Furthermore, we segment the macroscopic image of the eutectic high entropy alloy, and the area of various microstructures is distinguished. By combining the segmentation results and hardness experiments, we found that the hardness is positively correlated with the content of the body-centered cubic phase and negatively correlated with the lamella width. The whole procedure is also applied to a thermoelectric gradient material (PbSe-SrSe). Our work provides a feasible solution to generate macroscopic images based on SEM for further analysis of the correlations between the microstructures and spatial distribution, and can be widely applied to other types of microscopes.

A FEM-based model for failure initiation in the microstructure of gray cast iron under uniaxial compression

PurposeThe purpose of this study was to validate the feasibility of the proposed microstructure-based model by comparing the simulation results with experimental data. The study also aimed to investigate the relationship between the orientation of graphite flakes and the failure behavior of the material under compressive loads as well as the effect of image size on the accuracy of stress–strain behavior predictions.Design/methodology/approachThis paper presents a microstructure-based model that utilizes the finite element method (FEM) combined with representative volume elements (RVE) to simulate the hardening and failure behavior of ferrite-pearlite matrix gray cast iron under uniaxial loading conditions. The material was first analyzed using optical microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) to identify the different phases and their characteristics. High-resolution SEM images of the undeformed material microstructure were then converted into finite element meshes using OOF2 software. The Johnson–Cook (J–C) model, along with a damage model, was employed in Abaqus FEA software to estimate the elastic and elastoplastic behavior under assumed plane stress conditions.FindingsThe findings indicate that crack initiation and propagation in gray cast iron begin at the interface between graphite particles and the pearlitic matrix, with microcrack networks extending into the metal matrix, eventually coalescing to cause material failure. The ferritic phase within the material contributes some ductility, thereby delaying crack initiation.Originality/valueThis study introduces a novel approach by integrating microstructural analysis with FEM and RVE techniques to accurately model the hardening and failure behavior of gray cast iron under uniaxial loading. The incorporation of high-resolution SEM images into finite element meshes, combined with the J–C model and damage assessment in Abaqus, provides a comprehensive method for predicting material performance. This approach enhances the understanding of the microstructural influences on crack initiation and propagation, offering valuable insights for improving the design and durability of gray cast iron components.

From two segments and beyond: Investigating the onset of regeneration in Syllis malaquini.

Annelids feature a diverse range of regenerative abilities, but complete whole-body regeneration is less common, particularly in the context of the head and anterior body regeneration. This study provides a detailed morphological description of Syllis malaquini regenerative abilities. By replicating previous experiments and performing diverse surgical procedures, we explored the capacity of this species for whole-body regeneration. We detailed the precise timing of regeneration of particular structures such as the eyes, proventricle, pharyngeal tooth, nuchal organs, and body pigmentation after amputation. Our high-resolution scanning electron microscopy and confocal laser-scanning microscopy images provide details of the blastema region, revealing that while anal opening remains in connection to the exterior environment, oral opening is formed "de novo" during blastema differentiation. Additionally, we performed amputations to isolate fragments consisting of one, two, and three segments from the intestinal trunk region. We found that S. malaquini requires at least two to three segments to successfully regenerate the whole body. In addition, we verified a variable capacity to regenerate depending upon the gut region, with structures of the foregut greatly impairing some steps of the regenerative process. Our work notably addresses the gap in knowledge concerning gut formation and its impact on regenerative capabilities. Ongoing research is crucial to unravel the role of gut tissue specificity and plasticity during regeneration in annelids, and particularly in syllids.

Post-mortem study and long cycling stability of silica/carbon composite as anode in Li-ion cells

The present work emphases on the post-mortem study of silica/carbon composite as functional anode in Li-ion batteries (LIBs). Herein, the silica/carbon composite is synthesized by facile in-situ hydrothermal technique. The x-ray diffraction (XRD) pattern indicates the amorphous nature of silica/carbon composite. The stacked sheet-like morphology of silica/carbon composite is seen in the high-resolution transmission electron microscopy (HR-TEM) & scanning electron microscopy (SEM) images. In addition, Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, energy dispersive x-ray analysis (EDAX), and x-ray photoelectron spectra (XPS) characterizations of silica/carbon composite has been studied in detail. The rate capability of silica/carbon composite anode in LIB indicates 99% capacity retention after applying current density ranging from 50 mA g−1 to 1000 mA g−1, successively. The composite anode delivers a stable specific capacity ∼300 mAh g−1 at a current density of 100 mA g−1 for 500 cycles. Electrochemical impedance spectroscopy (EIS) study analyzed the faster Li-ion diffusion and increment in the diffusion coefficient by a factor of 1000 after 500 cycles. To the best of our knowledge, this is the first work on the post-mortem study of silica/carbon composite as anode in LIB. Post-cycling characterizations including XRD, FTIR, and SEM reveal the absence of any impurity phases and negligible volumetric expansion after prolonged cycling. It further confirms that the carbon present in the silica/carbon composite helps to accommodate the volumetric expansion of silica and prevents cracking of the anode over 500 cycles.

A Comparative Study on Dip Coating and Corrosion Behavior of Ti-13Zr-13Nb and Commercially Pure Titanium Alloys Coated with YSZ by Taguchi Design

This work evaluates experimentally the corrosion and tip testing of Ti-13Zr-13Nb joint implant alloys and commercially pure titanium (cp-Ti) covered with YSZ nanoceramic. Through the use of the Taguchi design of experiments (DOE) approach, the dip coating process produced a thin sticky covering. The effects of temperature, YSZ concentration, duration, and the level of Ti alloy substrate grinding during dip coating were investigated using a L9-type orthogonal Taguchi array to determine the deposition yield. The thickness and adhesion tests that were utilized to optimize the dip coating conditions served as the input data, and the Ti alloys were coated using the ideal dip coating technique parameters as previously mentioned. For commercial Ti, the ideal values for YSZ coating thickness and adhesion were 60°C, 10 seconds, 10% concentration, and 250 degrees of grinding; correspondingly, for Ti-13Zr-13Nb, the ideal values were 60°C, 10 seconds, 15% concentration, and 400 degrees of grinding. For both Cp-Ti and Ti-13Zr-13Nb, the obtained thickness and removal area (adhesion) were 58.5µm and 11.45%, respectively, and 69.5µm and 9.33%, respectively. High-resolution scanning electron microscopy (FE-SEM) images were used to study the coated alloys; optical microscopy and AFM were used to identify the microstructure and thickness measurements of the coated surfaces; EDAX was used to analyze the coating composition; and XRD was used to analyze the formed phases. The optimized coated Ti alloys' corrosion resistance was investigated in simulated body fluid (SBF) using electrochemical methods such as cyclic polarization and Tafel polarization, and the adhesion strength of the coatings was measured using a tip tester. The following corrosion-resistant values were used to compare Ti-13Zr-13Nb and coated Cp-Ti: In Ringer's solution at 37°C, both coating alloys—Cp-Ti and Ti-13Zr-13Nb—improved corrosion resistance; however, the coated Ti-13Zr-13Nb alloy demonstrated greater corrosion resistance than the coated Cp-Ti alloy (5.417×10-3 and 1.042×10-2, respectively).

In2O3-ZnO nanoporous photocatalyst modified with CuOx cocatalyst for enhanced photocatalytic bacterial inactivation and dye degradation

In this study, CuOx surface passivated In2O3 loaded porous ZnO, (CuOx/In2O3(x%)-ZnO)), were synthesized utilizing a solvothermally produced organic–inorganic ZnS(en)0.5 hybrid material. The high-resolution scanning electron microscopy (HR-SEM) and transmission electron microscopy (TEM) images of the CuOx/In2O3(2.5%)-ZnO nanocomposite reveal a macrosheet-shaped morphology comprising nanosized grains. The photocatalytic behavior of all the synthesized CuOx/In2O3(x = 0,1,2.5, and 5%)-ZnO nanocomposites were examined against aqueous dye solutions of orange II, and bisphenol A, E. coli bacteria under one sun illumination. The CuOx/In2O3(2.5%)-ZnO nanocomposite exhibits enhanced photoactivity for cationic dyes (eosin Y) than that for anionic (orange II). The results indicate that cationic dyes undergo photocatalytic degradation, whereas the anionic dyes adsorb on the CuOx/In2O3(2.5%)-ZnO nanocomposite surface, reducing the removal of organic pollutants. The optimal nanocomposites, CuOx/In2O3(2.5%)-ZnO photocatalyst exhibit maximum photodegradation performance of 99%, 94%, 27% for orange II dye, eosin dye, BPA, and 98% for E. coli inactivation within 180 min, respectively. The CuOx/In2O3(2.5%)-ZnO nanocomposite was successfully demonstrated to be an effective photocatalyst and excellent antibacterial agent. Finally, the charge transfer mechanism during photocatalytic organic decomposition and bacterial inactivation was studied.

Evaluating nickel removal efficacy of Filtralite under laboratory conditions: Implications for sustainable urban drainage systems

Our study deals with the critical issue of heavy metal pollution in urban runoff; we focused particularly on the threat posed by heavy metals such as nickel to living organisms and water resources owing to their toxicity at low concentrations and non-biodegradability. In this study, we evaluated the efficacy of Filtralite, a filtration medium with excellent hydraulic properties, in removing nickel from water through laboratory experiments and advanced simulation tools. We analysed the geochemical processes involved in nickel removal, including precipitation and adsorption. Importantly, we implemented an innovative approach for numerical modelling using HP1, by combining HYDRUS-1D and PHREEQC for modelling solute transport in porous media and geochemical reactions, respectively. The experimental results revealed that the Filtralite-laden column achieved a removal efficiency of 93.5 % for injected nickel. We observed a significant increase in the effluent pH from 7.0 to 11.5 during the interaction with Filtralite, affecting the solubility of the nickel phases. The model showed the highest nickel concentration in the initial column layers because of rapid chemical precipitation and adsorption upon contact with Filtralite. High-resolution scanning electron microscopy images confirmed the presence of amorphous precipitates around the soil particles, aligning with the changes in pH. This study contributes significantly to environmental engineering and urban water management by introducing an innovative numerical model in HP1 to accurately simulate the removal of nickel using Filtralite. These findings validate the efficiency of Filtralite in extracting nickel from aqueous solutions. Thus, Filtralite is a strong candidate for inclusion in sustainable urban drainage systems.

Green synthesis of nanocomposite based on magnetic hydroxyapatite using Falcaria vulgaris Bernh leaf extract to remove tartrazine dye from aqueous solution

To mitigate the adverse impacts of water pollution, the application of nanotechnology in dye removal and by-product reduction has the potential to establish a sustainable potable water supply. For these methodologies, the materials must involve exhibit qualities such as simplicity, high efficiency, eco-friendliness, reusability, and affordability. This study presents a novel porous magnetic hydroxyapatite nanocomposite coated with zinc oxide (Fe3O4@HAP@ZnO). Initially, zinc oxide nanoparticles were generated via a green synthesis method, where a zinc nitrate solution was combined with an aqueous extract from the Falcaria Vulgaris Bernh plant, serving as a reducing and stabilizing agent. These were then coated onto the magnetic hydroxyapatite.Verification of successful nanocomposite synthesis was obtained through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray spectroscopy (EDS), vibrating-sample magnetometer (VSM), High-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) images further substantiated these results. The synthesized nanocomposite exhibited a normal particle size distribution of approximately 89 nm. To achieve maximal decolorization efficiency, pertinent parameters were scrutinized and optimized through a detailed experimental design. Under optimal conditions, the nanocomposite's ability to decolorize tartrazine dye in an aqueous solution was evaluated. Remarkably, the highest observed efficiency approached 98 %, employing 0.07 g of the nanocomposite at 90 degrees Celsius, pH 6.4, over a span of 30 min. Further exploration of the nanocomposite's reusability revealed it could sustain an efficiency exceeding 90 % across 11 successive cycles, boasting an impressive capacity of 1398 (mgg-1).

SARS-CoV-2 Spike Protein Stimulates Macropinocytosis in Murine and Human Macrophages via PKC-NADPH Oxidase Signaling.

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). While recent studies have demonstrated that SARS-CoV-2 may enter kidney and colon epithelial cells by inducing receptor-independent macropinocytosis, it remains unknown whether this process also occurs in cell types directly relevant to SARS-CoV-2-associated lung pneumonia, such as alveolar epithelial cells and macrophages. The goal of our study was to investigate the ability of SARS-CoV-2 spike protein subunits to stimulate macropinocytosis in human alveolar epithelial cells and primary human and murine macrophages. Flow cytometry analysis of fluid-phase marker internalization demonstrated that SARS-CoV-2 spike protein subunits S1, the receptor-binding domain (RBD) of S1, and S2 stimulate macropinocytosis in both human and murine macrophages in an angiotensin-converting enzyme 2 (ACE2)-independent manner. Pharmacological and genetic inhibition of macropinocytosis substantially decreased spike-protein-induced fluid-phase marker internalization in macrophages both in vitro and in vivo. High-resolution scanning electron microscopy (SEM) imaging confirmed that spike protein subunits promote the formation of membrane ruffles on the dorsal surface of macrophages. Mechanistic studies demonstrated that SARS-CoV-2 spike protein stimulated macropinocytosis via NADPH oxidase 2 (Nox2)-derived reactive oxygen species (ROS) generation. In addition, inhibition of protein kinase C (PKC) and phosphoinositide 3-kinase (PI3K) in macrophages blocked SARS-CoV-2 spike-protein-induced macropinocytosis. To our knowledge, these results demonstrate for the first time that SARS-CoV-2 spike protein subunits stimulate macropinocytosis in macrophages. These results may contribute to a better understanding of SARS-CoV-2 infection and COVID-19 pathogenesis.

Adsorptive Removal of Selected Toxic Metals from Pharmaceutical Wastewater using Fe<sup>3</sup>O<sup>4</sup>/ZnO Nanocomposite

Pharmaceutical wastewater is a major source of environmental contamination, often containing toxic metals that pose significant threats to ecosystems and public health. This study explores the potential of magnetite/zinc oxide (Fe3O4/ZnO) nanocomposites prepared using a sol-gel method for the removal of lead, cadmium, and copper ions from pharmaceutical wastewater. The nanocomposite was characterized using X-ray diffraction (XRD), High-resolution scanning electron microscopy (HRSEM)/energy dispersive spectroscopy (EDS) and Fourier transmission infrared spectroscopy (FTIR). The XRD analysis of the nanocomposite identified 2θ (theta), of 31.7º, 34.4º, 36.2º, 47.5º, 56.6º, 62.8º, 66.3º, and 67.9º which correspond to the crystal planes of (100), (002), (101), (102), (110), (103), (200), and (112), respectively. The diffraction peaks associated with Fe3O4 at 2θ of 18.02º, 29.4º, and 43.3º, related to the crystal planes of (111), (220), and (400), respectively of the Fe3O4 phase. The HRSEM image of the nanocomposite exhibited spherical-shaped structures of Fe3O4/ZnO, and some irregular shapes. The effects of the contact time, dosage and temperature on the removal percentage of toxic metal ions were studied. Freundlich and Langmuir isotherm constants and correlation coefficients were determined and the equilibrium process was better described by the Langmuir isotherm. The adsorption process followed a second order kinetics and the thermodynamic parameters showed that the involved process was spontaneous. These findings contribute to the advancement of environmentally friendly technologies for the pharmaceutical industry and the broader field of wastewater remediation.

Aggregation analysis of laser generated silver-109 nanoparticles

This study investigates the aggregation behavior of stabilizer-free silver-109 nanoparticles synthesized via laser ablation synthesis in solution (LASiS) using a pulsed fiber laser equipped with a 2D galvoscanner. High-resolution scanning electron microscopy (HR SEM) imaging and laser desorption/ionization mass spectrometry (LDI MS) were employed to analyze changes in nanoparticle morphology and silver-109 clusters signal intensi-ty, providing insights into their stability and performance.

Efficient photocatalytic degradation of water pollutant Brufen using lutetium doped cerium oxide nanoparticles synthesized by chemical precipitation method

BackgroundPlants act the foremost source of molecules for the advancement of new drugs regarding anti-inflammatory action. In recent years, pharmaceutical compounds have been categorized as the emerging pollutants and have grabbed the attention of the researchers due to their existence in wastewater. They have been detected in drinking water which shows that the wastewater treatment plants are always not efficacious. These contaminants are pernicious if present in higher dosage and cause several risk factors to humans, animals, and aquatic systems. Ibuprofen, one of the most prescribed analgesics found to cause severe damage to stomach and intestine has been subjected to photocatalytic degradation using Lutetium doped Cerium oxide nanoparticles. The nanoparticles were synthesized using chemical precipitation method which is cost effective, simple, and ecofriendly. MethodsThe synthesized nanomaterial was characterized and confirmed using several analytical techniques like X-Ray Diffraction studies (XRD), Fourier Transform-Infrared Spectroscopy (FT-IR), UV-Diffuse Reflectance Spectroscopy (UV-DRS), High Resolution Scanning Electron Microscopy (HRSEM), X-Ray energy dispersive spectroscopy (EDAX), High Resolution Transmission Electron Microscopy (HRTEM), and X-ray Photoelectron Spectroscopy (XPS). Significant findingsXRD data revealed the cubic shape of the nanoparticles with approximate size of 6–12 nm. FT-IR study confirmed the presence of metal oxide peak at 550 cm−1 along with the peaks of other functional groups. HRSEM and HRTEM images confirmed cubic structure validating the XRD results. The band gap of the synthesized nanoparticles decreased from 3.25 eV to 2.90 eV in comparison with the pristine CeO2 with LuCeO2. XPS results revealed the oxidation state of lutetium as +3. The photocatalytic conditions were optimized and the optimization study confirms that the catalyst effectively degrades the drug. The degradation efficiency was calculated and was observed to be 92%. Real sample analysis was also performed using Brufen 200 tablet which confirms the practical application of the photocatalyst.

Reproducible Quantification of the Microstructure of Complex Quenched and Quenched and Tempered Steels Using Modern Methods of Machine Learning

Current conventional methods of evaluating microstructures are characterized by a high degree of subjectivity and a lack of reproducibility. Modern machine learning (ML) approaches have already shown great potential in overcoming these challenges. Once trained with representative data in combination with objective ground truth, the ML model is able to perform a task properly in a reproducible and automated manner. However, in highly complex use cases, it is often not possible to create a definite ground truth. This study addresses this problem using the underlying showcase of microstructures of highly complex quenched and quenched and tempered (Q/QT) steels. A patch-wise classification approach combined with a sliding window technique provides a solution for segmenting entire microphotographs where pixel-wise segmentation is not applicable since it is hardly feasible to create reproducible training masks. Using correlative microscopy, consisting of light optical microscope (LOM) and scanning electron microscope (SEM) micrographs, as well as corresponding data from electron backscatter diffraction (EBSD), a training dataset of reference states that covers a wide range of microstructures was acquired in order to train accurate and robust ML models in order to classify LOM or SEM images. Despite the enormous complexity associated with the steels treated here, classification accuracies of 88.8% in the case of LOM images and 93.7% for high-resolution SEM images were achieved. These high accuracies are close to super-human performance, especially in consideration of the reproducibility of the automated ML approaches compared to conventional methods based on subjective evaluations through experts.

Ultra-thin silver films grown by sputtering with a soft ion beam-treated intermediate layer

Silver thin films have wide-ranging applications in optical coatings and optoelectronic devices. However, their poor wettability to substrates such as glass often leads to an island growth mode, known as the Volmer–Weber mode. This study demonstrates a method that utilizes a low-energy ion beam (IB) treatment in conjunction with magnetron sputtering to fabricate continuous silver films as thin as 6 nm. A single-beam ion source generates low-energy soft ions to establish a nominal 1 nm seed silver layer, which significantly enhances the wettability of the subsequently deposited silver films, resulting in a continuous film of approximately 6 nm with a resistivity as low as 11.4 µΩ.cm. The transmittance spectra of these films were found to be comparable to simulated results, and the standard 100-grid tape test showed a marked improvement in adhesion to glass compared to silver films sputter-deposited without the IB treatment. High-resolution scanning electron microscopy images of the early growth stage indicate that the IB treatment promotes nucleation, while films without the IB treatment tend to form isolated islands. X-ray diffraction patterns indicate that the (111) crystallization is suppressed by the soft IB treatment, while growth of large crystals with (200) orientation is strengthened. This method is a promising approach for the fabrication of silver thin films with improved properties for use in optical coatings and optoelectronics.

Efficiency enhancement of perovskite-sensitized solar cell based on electrospun titania nanofibers coated in organic-inorganic hybrid metal trihalide nanocrystals

In this work, we have developed highly efficient, flexible, and thermally stable photoanode materials for perovskite-sensitized solar cells (PSCs). Methylammonium lead iodide (MAPbI3 or CH3NH3PbI3) coated TiO2 nanofibers (TNFs) were prepared by two step process. The cubic crystalline nature of MAPbI3 and the semi-crystalline nature of TNFs were confirmed by X-ray diffraction. The functional groups present in the photoanode materials were identified by Fourier-transform infrared spectroscopy. From UV–visible spectral studies, the absorption maximum of MAPbI3-coated TNFs was observed at 754 nm. High-resolution transmission electron microscopy and scanning electron microscopy images of MAPbI3 and TNFs showed a polycrystalline nature and uniform fiber structures, respectively. The highest electrical conductivity of 5.29 × 10−4 S/cm was achieved by the MAPbI3-coated TNFs photoanode, as measured by electrochemical impedance spectroscopy at room temperature. MAPbI3-coated TNFs, Spiro-OMeTAD, and gold chloride were used as the photoanode, hole transport material, and back electrode, respectively, in a PSC. A PSC constructed with MAPbI3-coated TNFs yielded an efficiency of 13.12%, bettering the 11.48% efficiency of a PSCs constructed from MAPbI3-coated TiO2 nanoparticles.

The study of CO2 reforming of methane over Ce/Sm-promoted NiCaAl catalysts

In this work, we synthesized Ce and Sm-promoted NiCaAl layered catalysts via co-precipitation and freeze-drying strategies for alleviating some problems, such as coke deposition and agglomeration of active sites, in dry reforming of methane. Employing such promoters leads to rising O2 vacancies on the catalyst's surface, resulting from adsorbing CO2 gas under the reaction. X-ray diffraction (XRD) analysis confirmed the formation of a hydrotalcite network. High-resolution transmission electron microscopy (HR-TEM) and field emission scanning electron microscopy (FE-SEM) images also indicated a wealth of nanocatalysts, well distributed on the surface and within a porous scaffold structure. The temperature-programmed reduction (H2-TPR) proved that cerium (H2 consumption = 1.2 mmol.g-1) could weaken the interactions between nickel and Ca/Al, leading to better reducibility than samarium (H2 consumption = 1.35 mmol.g-1). Moreover, the temperature-programmed deposition (CO2-TPD) showed the Ce-promoted catalyst possesses more basic sites (0.41 mmol.g-1) on its surface than the Sm-enhanced one (0.25 mmol.g-1). Consequently, the Ce-enhanced catalyst with a smaller crystallite size (8.9 nm), higher dispersion of Ni (10.8%), better reducibility, and more basic sites, which caused the highest methane conversion (82%), and H2/CO ratio (0.9) at 700 °C without any coke deposition after 5 h of time on stream.

Growth and characterization of gold nanoislands & quantum dots on marker-based SiO2/Si substrate for SEM resolution intercomparison studies

A scanning electron microscope (SEM) is the powerhouse tool of nanoscience & nanotechnology and the high resolution is one of the important parameters that decide the instrument’s quality. The reference materials (RM) like gold nanoislands or tin spheres on carbon substrate separated by a nanogap are often used to get the practically attainable resolution of the SEM instrument. Such RM contains millions of gold nanoislands and nanogaps but all of these RMs are non-traceable. Hence the practically obtained high resolution of an SEM remains doubtful unless and until intercompared with traceable RM. The development of a new SEM resolution test specimen sample with localized markers for the identification of a traceable critical dimension of a nanogap on a user-friendly SiO2/Si or Si3N4/Si chip is reported here. First, thin films of gold with thickness < 5 nm (ultra-thin film) and of about 10 nm (thin film) were deposited on a pre-patterned marker SiO2/Si chip to form the gold nanoparticles (Au NPs) by thermal annealing technique. The high-resolution SEM images show the formation of gold quantum dots (Au QDs) (average particle diameter <D> ∼ (18 ± 1) nm and average gap between two particles <S> ∼ (6 ± 1) nm) and gold nano-islands (Au NIs) (<D> ∼ (101 ± 3) nm and <S> ∼ (104 ± 2) nm). FESEM images show densely packed nano-islands exhibiting spherical geometry which is explained using dewetting mechanism followed by Ostwald ripening and coalescence resulting formation of Au QDs and Au NPs. Further, these marker-based resolution test chips can be used in inter or intra-comparison studies due to pre-patterned markers. First-time development of QDs on marker chip gives access to a particular nanogap among the millions of nanogaps present on the substrate, this type of RM will be used for inter-laboratory comparison studies in the future.

High-Resolution Scanning Electron Microscopy Imaging to Understand the Growth Kinetics of Nickel Nanorods.

In the present work, the growth kinetics of nickel nanorods inside commercially available Whatman nanoporous membrane is explored to achieve uniform deposition over a large area of the membrane. Uniform electrodeposition inside nanopores requires continuous presence of solute ions near the deposition site and reduction of ions. To control ion diffusion and reduction near the deposition site, the effect of DC potential and pulsed potential with various duty cycles and solution temperatures is analyzed. Time-dependent variation in deposition current is recorded for all experiments. For different experimental conditions, high-resolution scanning electron microscopy (SEM) image is acquired. SEM along with the current density profile helped to understand the deposition mechanism for various growth conditions. Experiments confirmed that pulse deposition with a small duty cycle is promising to achieve uniform deposition. Also, by changing the pulse duty cycle, a sectioned nanostructure can be obtained. Based on the electron microscopic observation for various deposition conditions used in this work, it is concluded that initially nickel ions adhere to the pore surfaces due to high surface energy. When a potential is applied, ions reduce and a hollow nanotube structure forms. With time, concentric growth continues by forming a solid nanorod structure.

Photovoltaic studies on iodine incorporated titania aerogel nanocomposites

Iodine incorporated titania aerogel nanocomposites were synthesized by the sol–gel method. The nanocomposites were obtained by varying the concentration of iodine as 0, 5, 10, and 20% with respect to the weight percentage of titania. All the synthesized nanocomposites retained the crystallinity and anatase phase, confirmed by X-ray diffraction studies. High-resolution scanning electron microscope images of nanocomposites showed the porous structure with agglomeration by increasing the concentration of iodine. The energy dispersive spectrum revealed the entry of the iodine into the titania aerogel. The absorption edge of the nanocomposites from the UV–Visible spectroscopy showed the red-shifted and thereby reducing the band gap with increasing iodine concentration. The photovoltaic performance of the synthesized iodine-incorporated titania aerogel nanocomposites was performed using as photoanode in the quasi-solid dye-sensitized solar cell and found that the efficiency is increasing with increasing iodine in titania aerogel. The photostability and reproducibility of the device were greater than the pristine aerogel.

Shale Oil Occurrence Mechanisms: A Comprehensive Review of the Occurrence State, Occurrence Space, and Movability of Shale Oil

Shale oil resources are important supplements for the gradually decreasing oil production from conventional reservoirs. Although the exploitation and development of shale oil have achieved considerable progress in the last decade, the commercial extraction of hydrocarbons from shales is still difficult, especially in the lacustrine sedimentary basins of China. One of the key points controlling the successful extraction of hydrocarbons from shale systems is the understanding of the occurrence mechanism of shale oil. This study comprehensively summarizes the theories and techniques to characterize oil occurrence state, occurrence space, oil content, and oil movability in shale systems. Sophisticated instruments, such as high-resolution scanning electron microscopy and high-energy ray imaging, were utilized to qualitatively analyze the pore networks of shales. Advanced physical experiments and numerical simulation techniques, including step-by-step rock pyrolysis, solvent extraction, and NMR, were introduced to characterize shale oil adsorption and movability. By the comparative analysis of the occurrence space, it is found that the image observation technique especially focuses on concentrated pores, such as organic matter-hosted pores. The fluid injection technology yields particular pore size information, which should be calibrated using other information. The 3D digital core, demonstrating the spatial distribution of minerals and pores, is an effective input for shale oil flow simulation. Geological controls analysis about oil retention in organic-rich shales has found that the inorganic matter pores and fractures are probably the “sweet spot” of shale oil, due to the low oil adsorption and high light hydrocarbons content. Many physical experiments measure the total free oil content but neglect the hydrocarbon–rock interaction and the sequential migration of hydrocarbon compounds. Thus, micro-scaled experiments measuring the hydrocarbon adhesion forces are needed to uncover the occurrence mechanism of shale oil in the future.