High-resolution Electron Microscopy Research Articles

Insight into Antiviral Activity of Ag/TiO2 Nanocomposites Against Influenza H1N1 Virus and Its Antiviral Mechanism.

Synthesis and characterization of silver (Ag)/titanium dioxide (TiO2) nanocomposite (ATA) to investigate its antiviral activity against the H1N1 influenza virus and antiviral mechanisms. A water-dispersible ATA was prepared by a photocatalytic reduction process from AgNO3 and TiO2. The characterization of ATA was performed by ultraviolet-visible spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy. The antiviral activities and the antiviral mechanism of ATA were investigated in detail by light microscopy, transmission electron microscopy and biological techniques such as cell cytotoxicity, 50% tissue culture infectious dose detection, western blot and reverse transcription-polymerase chain reaction. These results showed the successful synthesis of ATA nanocomposite with uniform particle size and distribution. It demonstrated the highly efficient antiviral activity of ATA in a dose- and time-dependent manner, as indicated by the reduction of viral titer and the reduction of cytopathic effects caused by viral infection. In the presence of ATA, the structure of the H1N1 influenza virus is directly destroyed and even disintegrated, with the damaged surface membrane proteins and fuzzy contour. It reduces the infection efficiency of influenza by suppressing the activity and expression of hemagglutinin and neuraminidase. The results of mechanistic studies suggested that ATA nanocomposite primarily interferes with virus attachment to viral receptors on the cell surface. Our study suggests that ATA may be a good antiviral candidate against the influenza virus. Compared with AgNPs alone, our synthesized ATA nanocomposites can achieve similar viral inactivation rates using only a much smaller concentration of AgNPs, greatly reducing the amount of AgNPs and their potential side effects. It has great practical value for attaching ATA to the high-efficiency particulate air network in the air purifier, which can kill the virus attached to it and limit its spread.

Performance of high-energy storage activated carbon derived from olive pomace biomass as an anode material for sustainable lithium-ion batteries

In this work, we investigate how activated carbon (AC) derived from olive pomace biomass can be used as an anode material in lithium-ion batteries. The biomass-derived activated carbon has the potential to be highly efficient, deliver high performance, sustainable, and cost-effective in LIBs-related production. The activated carbon is prepared by using H3PO4 as a chemical activation agent, and then calcining the obtained product at 500°C for different controlled atmospheres under (i) air (AC-Atm), (ii) vacuum (AC-Vac), and (iii) argon (AC-Arg). The different samples were systematically analyzed using scanning electron microscopy (SEM), High-resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS), X-ray fluorescence (XRF), X-ray diffraction (XRD), FT-IR and Raman spectroscopy, and thermogravimetric analysis (TGA) to assess their properties. The electrochemical properties of the carbonaceous materials were studied by galvanostatic cycling, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results showed high specific capacity and stable cycling performance, with capacities of 288, 184, and 56 mAh g-1 at the current density of 25 mA g-1 after 70 cycles for AC-Arg, AC-Vac, and AC-Atm respectively. Furthermore, the CE efficiency was nearly 100% from the first cycles. This study opens up interesting prospects and offers promising opportunities for more efficient recovery of unused olive pomace waste, by integrating it into energy storage applications, particularly sustainable lithium-ion batteries.

Molecular mechanisms of iron nanominerals formation in fungal extracellular polymeric substances (EPS) layers during fungus-mineral interactions

Extracellular polymeric substances (EPS), which envelop on fungal hyphae surface, interact strongly with minerals and play a crucial role in the formation of nanoscale minerals during biomineralization in nature environments. However, it remains poorly understood about the molecular mechanisms of nanominerals (i.e., iron nanominerals) formation in fungal EPS halos during fungus-mineral interactions. This process is vital because fungi typically grow attached to various mineral surfaces in nature. According to the changes of thickness of the fungal cell and EPS layers during the Trichoderma guizhouense NJAU 4742 and hematite cultivation experiments, we found that fungal biomineralization could trigger the formation of EPS layers. Fe-dominated nanominerals, aromatic C (283-286.1 eV), alkyl C (287.6-288.3 eV), and carboxylic C (288.4-289.1 eV) were the dominant chemical groups on the EPS layers, as determined by nanoscale secondary ion mass spectrometry (NanoSIMS), high-resolution transmission electron microscope (HRTEM), and carbon 1s near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Further, evidence from Fe K-edge X-ray absorption near-edge structure (XANES) and X-ray photoelectron spectroscopy (XPS) spectra indicated that oxygen vacancy (OV) was formed on the Fe-dominated nanomineral surface during fungus-mineral interactions, which played an important role in catalyzing H2O2 decomposition and HO∗ production. Taken together, the intrinsic peroxidase-like activity by reactive oxygen species (ROS) could modulate the Fe-dominated nanominerals formation in EPS layers to newly form a physical barrier between the cell and the external environments around hyphae, providing novel insights into the effects of ROS-mediated fungal-mineral interactions on fungal nutrient recycling, attenuation of contaminants, and biological control in nature environments.

Silica coated N-doped carbon modified with ruthenium nanoparticles: An effective waste derived carbon nanocatalyst in oxidation reactions and also its evaluation by DFT and anti-bacterial studies

This report presents the development of an inexpensive mesoporous nanocatalyst i.e. silica coated N-doped carbon modified with ruthenium nanoparticles (Ru/RuO2@NSAC). The carbon and nanosilica components were derived from waste materials namely waste tea extract and rice husk respectively highlighting the sustainable approach to the synthesis process. The nanocatalyst was thoroughly characterized using various advanced techniques such as Fourier transform infrared spectroscopy (FTIR), Powder X-ray diffraction (P-XRD), Field emission gun-scanning electron microscopy (FEG-SEM), Energy dispersive X-ray analysis (EDX), High resolution-transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) surface area analysis, X-ray resonance fluorescence (XRF) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). These characterizations provided comprehensive insights into the structural features of the nanocatalyst. XPS analysis confirmed the presence of both metallic ruthenium and Ru (IV) on the nanocatalytic support. The particle size of Ru/RuO2@NSAC was determined using Scherrer's equation and came out to be 21.37 nm. This nanocatalyst demonstrated remarkable performance as a robust heterogeneous catalyst for the oxidation of alkylarenes and alcohols to their corresponding carbonyl compounds. It exhibited excellent recyclability, maintaining its activity for up to five consecutive runs. Post-recycling, the catalyst was again characterized by P-XRD and FEG-SEM to ensure its structural integrity. Additionally, the antibacterial activity of Ru/RuO2@NSAC was evaluated against both Gram-positive and Gram-negative bacteria. A density functional theory study was also conducted to support the experimental findings, providing a theoretical basis for the observed catalytic behavior.

Making the link between ADF and 4D STEM: Resolution, transfer and coherence

Abstract Steve Pennycook is a pioneer in the application of high-resolution scanning transmission electron microscopy (STEM) and in particular the use of annular dark-field (ADF) imaging. Here we show how a general framework for 4D STEM allows clear links to be made between ADF imaging and the emerging methods for reconstructing images from 4D STEM data sets. We show that both ADF imaging and ptychographical reconstruction can be thought of in terms of integrating over the overlap regions of diffracted discs in the detector plane. This approach allows the similarities in parts of their transfer functions to be understood, though we note that the transfer functions for ptychographic imaging cannot be used as a measure of information transfer. We also show that conditions of partial spatial and temporal coherence affect ADF imaging and ptychography similarly, showing that achromatic interference can always contribute to the image in both cases, leading to a robustness to partial temporal coherence that has enabled high-resolution imaging.

Green biogenic synthesis of magnetite nanoparticles from indigenous Banksia Ashbyi leaf for enhanced sonochemical dye degradation

Abstract Developing alternative green and sustainable technologies to prevent, reduce, and remove toxic dyes present in effluent generated by the textile industry is of global importance. In this study, magnetite (Fe3O4) nanoparticles (MNPs) were successfully synthesized using a co-precipitation method that used Indigenous Banksia Ashbyi (BA) leaf extract in varying amounts (BA-MNP 1 to BA-MNP 4), to modulate particle size and size distribution. The formation of the MNPs was confirmed by a range of characterization techniques that included UV–visible spectrophotometry, Fourier transform infrared (FTIR) spectroscopy, x-ray diffraction (XRD) spectroscopy, thermo-gravimetric analysis (TGA) and scanning (FIBSEM) and high-resolution transmission (HRTEM) electron microscopy. The presence of the Fe–O bond located at 551 cm−1 in the FTIR spectra and XRD analysis of the samples confirmed the formation of crystalline MNPs. FIBSEM and HRTEM images of the BA-MNP 4 sample confirmed the MNPs were spherical (18 ± 5 nm) and tended to agglomerate. Moreover, UV–visible spectrophotometry revealed a board absorption band and an optical band-gap energy of 2.65 eV. The catalytic activity of BA-MNP 4 samples towards the degradation of a commercially available navy-blue RIT dye (BRD) were investigated under three operational senarios: 1) ultrasonic irradiation (US) + BRD; 2) BA-MNP 4 + BRD, and 3) US + BRD + BA-MNP 4. The investigation found there was an additive effect when US (80 W) was used in conjunction with BA-MNP 4 s during the dye degradation process. With no US, the BA-MNP 4 sample only achieved a dye degradation of 52% in 25 min. However, over the same period of time with US, the BA-MNP 4 sample achieved a dye degradation of 89.92%. In addition, kinetic modelling found the combined US and BA-MNP 4 process followed a pseudo-first-order kinetic model.

Trans, Trans-Farnesol Enhances the Anti-Bacterial and Anti-Biofilm Effect of Arachidonic Acid on the Cariogenic Bacteria Streptococcus mutans and Streptococcus sobrinus.

Streptococcus mutans and Streptococcus sobrinus are Gram-positive bacteria involved in the development of dental caries, as they are able to form biofilms on tooth enamel, ferment sugars into acids, and survive under acidic conditions. This ultimately leads to a local lowering of the pH value on the tooth surface, which causes enamel cavities. One measure to reduce caries is to limit the growth of cariogenic bacteria by using two anti-bacterial agents with different mechanisms of action. The hypothesis of this study was that the anti-bacterial activity of ω-6 polyunsaturated arachidonic acid (AA) against S. mutans and S. sobrinus can be enhanced by the sesquiterpene alcohol trans, trans-farnesol (t,t-farnesol). The anti-bacterial activity of single and combined treatment was determined by the checkerboard assay. Bacterial viability was assessed by live/dead SYTO 9/propidium iodide (PI) staining on flow cytometry. Anti-biofilm activity was determined by MTT metabolic assay, crystal violet staining of biofilm biomass, SYTO 9/PI staining by spinning disk confocal microscopy (SDCM) and high-resolution scanning electron microscopy (HR-SEM). t,t-Farnesol lowered the minimum inhibitory concentration (MIC) and the minimum biofilm inhibitory concentration (MBIC) of AA at sub-MICs. AA reduced the metabolic activity of preformed mature biofilms, while t,t-farnesol had no significant effect. The enhanced anti-bacterial effect of the combined t,t-farnesol/AA treatment was further evidenced by increased PI uptake, indicating membrane perforation. The enhanced anti-biofilm effect was further verified by SDCM and HR-SEM. Gene expression studies showed reduced expression of some biofilm-related genes. Altogether, our study suggests a potential use of the two naturally occurring compounds arachidonic acid and t,t-farnesol for preventing biofilm formation by the cariogenic bacteria S. mutans and S. sobrinus. These findings have implications for caries prevention.

Surfactant Molecules and Nano Gold on HOPG: Experiment and Theory

Excessive surfactant molecules within the solution adhere to highly ordered pyrolytic graphite (HOPG) when a droplet containing gold nanorods evaporates, leading to the emergence of a unique coffee-ring pattern. The combination of surface hydrophobicity and evaporation of the aqueous phase results in a stick-slip motion, which enhances the convective hydrodynamics of suspended particles. This phenomenon initiates interactions that influence the deposition and flow dynamics inside the droplet. High-resolution scanning electron microscopy (HRSEM) does not provide significant insights into regions potentially linked to cetyltrimethylammonium bromide (CTAB) molecules, whereas the atomic force microscope (AFM) displays the presence of gold nanoparticles arranged by CTAB within specific CTAB patches. The layers forms with varying heights and gaps between them, indicating diverse adhesion of CTAB. The analytical focus lies on the quantitative assessment of CTAB molecules, stripe dimensions, and energy profiles influenced by concentration and the effective positioning of CTAB-coated gold nanorods in CTAB-covered regions. AFM examination reveals CTAB molecular stripes on HOPG, showing a binding energy of -20 kJ/mol with the surface, -10 kJ/mol for nitrogen bonding with HOPG, and a total binding energy (BE) of -60 kJ/mol, considering various contributing factors. Completely parallel aligned molecules (CPAM) exhibit higher binding energy than non-perfectly aligned molecules (NPAM) due to maximum Van der Waals (VdW) interactions, ideal electrostatic interactions, and minimal steric repulsion. The difference in binding energy between perfectly and non-perfectly aligned molecules is around 20kJ/mol, emphasizing the importance of molecular orientation. As temperature rises from 298K to 348K, the likelihood of NPAM desorption increases significantly, with the binding energy shifting from 2.5kJ/mol to 4.1kJ/mol. Temperature significantly influences the equilibrium of molecules on HOPG surfaces. The emphasis is on elucidating the alterations in energy levels during nanorod aggregation on CTAB areas compared to bare HOPG surfaces, underscoring the impact of nanorods on CTAB micelle deformation energy. Observations on the variation in CTAB desorption rates with temperature changes underscore the dynamic nature of molecular binding energy associated with surface properties, underscoring the importance of molecular configuration and energy transfers in nanoscale systems.

Endochondral ossification: insights into the cartilage mineralization processes achieved by an anhydrous freeze substitution protocol

Growth plate cartilage (GP) serves as a dynamic site of active mineralization and offers a unique opportunity to investigate the cell-regulated matrix mineralization process. Transmission electron microscopy (TEM) provides a means for the direct observation of these mechanisms, offering the necessary resolution and chemical analysis capabilities. However, as mineral crystallinity is prone to artifacts using aqueous fixation protocols, sample preparation techniques are critical to preserve the mineralized tissue in its native form. We optimized cryofixation by high-pressure freezing followed by freeze substitution in anhydrous acetone containing 0.5% uranyl acetate to prepare murine GP for TEM analysis. This sample preparation workflow maintains cellular and extracellular protein structural integrity with sufficient contrast for observation and without compromising mineral crystallinity. By employing appropriate sample preparation techniques, we were able to observe two parallel mineralization processes driven by chondrocytes: 1) intracellular- and 2) extracellular-originating mineralized vesicles. Both mechanisms are based on sequestering calcium phosphate (CaP) within a membrane-limited structure, albeit originating from different compartments of the chondrocytes. In the intracellular originating pathway, CaP accumulates within mitochondria as globular CaP granules, which are incorporated into intracellular vesicles (500-1000 nm) and transported as granules to the extracellular matrix (ECM). In contrast, membrane budding vesicles with a size of approximately 100-200nm, filled with needle-shaped minerals were observed only in the ECM. Both processes transport CaP to the collagenous matrix via vesicles, they can be differentiated based on the vesicle size and mineral morphologies. Their individual importance to the cartilage mineralization process is yet to be determined. Statement of SignificanceWe do not fully understand the process by which epiphyseal cartilage mineralizes - a vital step in endochondral bone formation. Previous work has proposed that mitochondria and intracellular vesicles are storage sites for the delivery of mineral to collagen fibrils. However, these concepts are founded on results from in vitro models of mineralization; no prior work has observed mineral-containing intracellular vesicles or mitochondria in developing epiphyseal cartilage. Here we developed a new cryofixation preparation route for transmission electron microscopy (TEM) imaging that has disclosed a cell-regulated process of mineralization in epiphyseal cartilage. High resolution TEM images revealed an involvement of mitochondria and intracellular and extracellular vesicles in delivering transient mineral phases to the collagen fibrils to promote cartilage mineralization.

Size Effects on the Magnetic Properties of a System of ε-Fe2O3 Nanoparticles Embedded in a SiO2 Xerogel Matrix

A representative series of samples consisting of fine ε-Fe2O3 nanoparticles uniformly distributed over the SiO2 xerogel matrix with an iron oxide content of 5‒33 wt % has been synthesized and studied by mutually complementary physical methods. It has been shown by the X-ray diffractometry and high-resolution electron microscopy examination that, with increasing iron oxide concentration, the average particle size <d> increases from 4 to 11 nm. According to the X-ray diffractometry and Mӧssbauer spectroscopy data, the samples with an iron oxide content of 5–20 wt % are single-phase, while at the highest Fe2O3 concentration (33 wt %), the β-Fe2O3 and α-Fe2O3 phases arise. As the average particle size <d> increases, a monotonic increase in coercivity HC and remanent magnetization MR of the synthesized systems at room temperature is observed, which is indicative of their magnetic hysteresis. The magnetic transition known to occur in the ε–Fe2O3 oxide manifests itself in all the investigated samples as a drastic change in the HC and MR values at 150–75 K. At the same time, a thorough analysis of the temperature dependence of the real part of the ac magnetic susceptibility χ′ has shown that the particles with a size smaller than a critical value of dC ∼ 6.5 nm do not undergo the magnetic transition and have a much lower magnetic anisotropy constant as compared with coarser particles (d >dC). It has been found that, in the low-temperature region, the magnetic moments of these fine particles experience superparamagnetic blocking. It has been established that the size effects that arise in ultra-fine ε–Fe2O3 particles has a serious impact on the macroscopic magnetic properties of the highly dispersed systems based on them.

The Role of Al/Ti in Precipitate-Strengthened and Austenite-Toughened Co-Free Maraging Stainless Steel.

The strength of ultra-low carbon maraging stainless steels can be significantly enhanced by precipitating nanoscale intermetallic secondary phases. Retained or reversed austenite in the steel can improve its toughness, which is key to achieving an ideal combination of strength and toughness. Ti and Al are often used as cost-effective strengthening elements in maraging stainless steels but the synergistic toughening and strengthening mechanisms of Ti and Al have not been studied. To investigate the synergistic toughening and strengthening mechanisms of Ti and Al in Co-free maraging stainless steels, this paper focuses on the microstructure and mechanical properties of three alloys: Fe-12Cr-11Ni-1.7Al-0.5Ti (Steel A), Fe-12Cr-11Ni-0.5Ti (Steel B), and Fe-12Cr-11Ni-1.7Al (Steel C). The impact of Ti and Al on the microstructure and mechanical properties was investigated using X-ray diffraction (XRD), high-resolution transmission electron microscopy (TEM), and thermodynamic simulations. The relationship between microstructure, strength, and toughness is also discussed. The results indicated that Steel A, containing both Al and Ti, exhibited the highest strength level after solution treatment at 900 °C, with an ultimate tensile strength reaching 1571 MPa after aging at 540 °C. This is attributed to the simultaneous precipitation of spherical β-NiAl and rod-shaped η-Ni3Ti phases. Steel B, with only Ti, formed a significant amount of Ni-rich reversed austenite during aging, reducing its ultimate tensile strength to 1096 MPa. Steel C, with only Al, showed a high strength-toughness combination, which was achieved by forming dispersive nano-sized intermetallic precipitates of β-NiAl in the martensitic matrix with a slight amount of austenite. It is highlighted that Al has superior toughening and strengthening effects compared to Ti in the alloy system.

Impact of Dilute DIO Additive on Local Microstructure of Fluorinated, pNDI-Based Polymer Solar Cells.

The performance of all-polymer solar cells is often enhanced by incorporating solvent additives during solution processing. In particular, blends based on the model all-polymer system PBDBT:N2200 have been shown to have increased short-circuit current and fill factor when processed with dilute diiodooctane (DIO). However, the morphological mechanism that drives the increase in performance is often not well understood due to limitations in common characterization techniques. In this study, it is shown that a combination of X-ray techniques with cryogenic high-resolution transmission electron microscopy (HRTEM) analysis can provide a quantitative and spatially resolved picture of polymer chain orientation and alignment in all-polymer blends. It is found that DIO induces vertical phase separation in PBDBT-2F:F-N2200 and increases donor crystallite thickness in the pi-stacking direction leading to an acceptor-rich film surface. However, it is also shown that DIO does not disrupt the formation of face-on donor-acceptor interfaces. These findings suggest that dilute DIO primarily affects crystalline domain formation in single component regions as opposed to mixed regions; thus, dilute DIO can impact vertical charge transport pathways without sacrificing donor-acceptor interfacial connectivity.

Efficient Growth of 1D Van der Waals Heterostructures on Zeolite-Supported SWCNTs.

The controlled synthesis of 1D van der Waals (1D vdW) heterostructures, specifically single-walled carbon nanotubes encapsulated within boron nitride nanotubes (SWCNT@BNNT), presents a challenge due to an incomplete understanding of the factors influencing BNNT growth. This study investigates the growth yield of SWCNT@BNNT heterostructures produced using zeolite-supported SWCNT templates on SiO2-coated Transmission Electron Microscopy (TEM) grids, which enable in situ synthesis and thorough evaluation of each step without compromising the nanotube structure. The high-resolution TEM analysis reveals a significant improvement in BNNT coverage on individual nanotubes, increasing from 9% to 42%, through optimization of the ammonia borane precursor amount. A thorough comparison of BNNT growth efficiency is performed using zeolite-supported SWCNT templates against the current benchmark of free-standing SWCNT films, highlighting comparable synthesis yields despite different morphologies and SWCNT diameter distributions. By integrating all Raman and TEM data from the studied SWCNT@BNNT samples, a correlation between BNNT coverage and the intensity of the buckling R-mode of BNNTs is established, providing a reliable criterion for evaluating BNNT growth efficiency in 1D vdW heterostructures. This work advances the understanding and characterization of 1D vdW heterostructures, offering insights into synthesizing hetero-nanotubes using other types of SWCNT templates and paving the way for their diverse applications.

Catalytic reduction, antibacterial, and antioxidant activities of green synthesized silver nanoparticles using Coccinea grandies (L) Voigt leaf extract

In this study, silver nanoparticles (AgNPs) were synthesized using the aqueous extract of Coccinia grandis (L) Voigt leaf (CGL) extract using microwave irradiation method and the structure was elucidated by various techniques such as UV–Visible spectroscopy, Fourier transformation infrared spectroscopy (FT-IR), x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive x-ray spectroscopy (EDX), and high-resolution transmission electron microscopy (HR-TEM). The UV–visible spectroscopy confirmed the formation of AgNPs and SPR band appear at 420 nm. FT-IR analysis indicated the presence of –OH and –NH functional groups from secondary molecules of CGL capping the AgNPs surface. HR-TEM revealed spherical aggregates with an average size of 29.4 nm. EDX confirmed the presence of elemental silver. XRD analysis showed that the AgNPs had a face-cantered cubic (FCC) crystal structure. The CGL-AgNPs were used as a heterogeneous catalyst to reduce RhB and CR dyes from aqueous solutions in the presence of sodium borohydride (NaBH4). The results showed that greater than 95 % of catalytic reduction can be accomplished within 9 min. The biosynthesized AgNPs demonstrated notable antioxidant activity (82.89 % in the DPPH assay) and antibacterial activity with a Zone of inhibition ranging from 9 to 11 mm. These findings suggest that CGL can be used to synthesize new, cost-effective AgNPs using an environmentally friendly approach.

Effect of carbon coating on improved electrical and electrochemical performance of Li3Co2SbO6

Abstract We reported a novel high voltage cathode having layered structure and manifold improvement (144%) in electrochemical performance on carbon coating Li3Co2SbO6. The carbon-coated Li3Co2SbO6 has been prepared using a high temperature solid-state method in an air medium with appropriate stoichiometry of the oxide and carbon source (sucrose). The x-ray diffraction and high-resolution transmission electron microscopy results have confirmed homogeneous carbon coating on oxide (Li3Co2SbO6) surface without disturbing phase, structure and morphology. The immediate effect of carbon coating resulted in electrical conductivity enhancement of the carbon coated Li3Co2SbO6 by four order of magnitudes ∼2.79 × 10−4 Scm−1 at room temperature vis-a-vis pristine Li3Co2SbO6. The electrochemical performance of the carbon coated Li3Co2SbO6 has shown sustainable improvement indicating redox activity by more than one Li+ transaction. The carbon coated Li3Co2SbO6 cathode exhibited an initial discharge capacity of 110 mAhg−1 compared to 45 mAhg−1 for its pristine counterpart. The improvement in electrochemical capacity on carbon coating, as reported in this work, is the highest ever compared to prior literature reports on Li3Co2SbO6.

Boron-doped TiO2 nanoparticles for improved photoelectrochemical response via enhanced surface area and visible light absorption

The present study introduces boron doping into TiO2 nanoparticles to synthesize boron-doped TiO2 samples. The structural and morphological properties of the pristine and doped samples are investigated using X-ray diffraction, Raman spectroscopy, Field Emission Scanning Electron Microscopy (FESEM) and High Resolution Transmission Electron Microscopy (HRTEM) techniques. Photoelectrochemical measurements have confirmed that a 3 wt % concentration of boron doped TiO2 nanoparticles shows improved photoelectrochemical response compared to pristine TiO2 nanoparticles. An ∼285-fold improvement (∼0.97 mA/cm2 at 0.81 V vs RHE) is observed in 3 wt % boron doped TiO2 nanoparticles array as compared to the pristine (3.4 μA/cm2 at 0.81 V vs RHE) photoanode samples. Moreover, the enhanced surface area, suppressed recombination, effective charge separation/transport of photogenerated charge carriers, and improved visible light absorption due to boron doping result in a remarkably high current density.

Green Synthesis of Ag-Doped ZnO Nanoparticles Using Bael (A. marmelos) Leaves for Wastewater Remediation

Abstract The microwave-assisted technique proved highly successful in harnessing the Bael (A. marmelos) tree's natural properties to synthesize Ag-ZnO nanoparticles in an environmentally friendly manner. Through analysis of the various vibration modes evident in the Fourier transform infrared spectra, it became evident that functional groups are present on the nanoparticle surface, showcasing the intricate chemical composition achieved through this innovative synthesis approach. The nanoparticles dimensions, morphology, and surface features were investigated through advanced techniques such as high-resolution transmission electron microscopy and scanning electron microscopy. Analysis revealed that the synthesized Ag-ZnO nanoparticles typically ranged between 15 to 20 nm in size. When subjected to ultraviolet radiation, the silver-doped zinc oxide nanoparticles demonstrated remarkable photocatalytic prowess, effectively decomposing the dye known as methylene blue. The produced Ag-doped ZnO NPs are very good at reducing dye to 88% in about one hour. Characterization, as well as encouraging photocatalytic and antioxidant qualities, indicate the potential use of these synthesized Ag-doped ZnO NPs for environmental as well as vital uses.

Precipitation strengthening behavior of Custom 455 stainless steel during tempering at 420 °C

After solid solution at 850 °C, the Custom 455 was aged at 420 °C for different times. The hardness changes were measured using a Vickers hardness tester, and the microstructure and composition of the second phase were studied using atom probe tomography (APT) and high-resolution transmission electron microscopy (HRTEM). The APT results indicate that in the early stage of aging, Cu atoms first segregate and attract Ti to form CuTi clusters; As the aging time increases, Ti atoms in CuTi clusters attract Ni and form CuTiNi clusters, resulting in a rapid increase in sample hardness; Subsequently, CuNiTi clusters grew and gradually separated into Cu-rich and NiTi-rich particles; As the aging time further increases, some NiTi-rich particles grow into rod-shaped Ni3Ti precipitates, while others have Si atoms and grow into spherical G phase particles. The orientation relationship between Cu-rich phase, Ni3Ti phase, and G phase is: [100]M//[0–11]Cu//[-12–10]Ni3Ti//[100]G, (011)M//(111)Cu//(0004)Ni3Ti//(022)G. The formation of the Cu-rich, Ni3Ti, and G phase resulted in a hardness peak of 538 HV after 16 h of aging. Subsequently, the decrease in hardness caused by the coarsening of the Cu-rich and Ni3Ti particles was offset by the newly formed G phase, resulting in a slow decrease in hardness.

Micro- to nano-sized solid inclusions in magnetite record skarn reactions

Abstract. Magnetite is a widespread ore mineral in skarn systems and usually hosts a wide variety of inclusions. Micro- to nano-sized solid inclusions in magnetite are unique tools to track the evolutionary processes of its host mineral and, subsequently, to constrain the timing of the mineralization event. In this study, we characterize micro- to nano-sized solid inclusions in magnetite from the La Víbora magnesian skarn (Málaga, Spain) using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). TEM energy-dispersive X-ray spectrometry (EDS) analyses and compositional mapping expose two types of nano-inclusions oriented along the (111) of magnetite: type 1 includes dolomite, spinel, and Mg–Fe–Al silicate, and type 2 is made up of Mg–Fe–Al silicates enveloping the Mg-bearing amorphous silica phase. High-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), and fast Fourier transform (FFT) patterns reveal that the majority of the solid inclusions display non-oriented matrices compared to the host magnetite, precluding the possibility of sub-solidus processes. Instead, these inclusions are thought to preserve skarn mineral assemblages that were entrapped during the growth of magnetite. However, the local supersaturation of fluids trapped in the boundary layer of crystallizing magnetite is evidenced by coherent lattice orientation of precipitated and host magnetite and by the occurrence of an Mg-bearing amorphous silica phase. Our findings reveal that skarn reactions observed at field and microscopic scales are also recorded in nano-sized inclusions within magnetite. These observations underscore the significance of micro- to nano-scale solid inclusions in magnetite to decipher overprinted skarn reactions as well as constraining the timing of Fe mineralization events in skarns.

Micro-structure-property relationship of heavily drawn steel wires for large span suspension bridge cables

The outstanding combination of high strength and ductility of bridge cable steel wire is attributed to the cold drawing process with intermediate equivalent strain. However, the micro-structure-property relationship of heavily drawn steel wires for large span suspension bridge cables is not well understood. In this study, defects-controlled deformation in nano-scale interfaces between ferrite and cementite phases with heavily cold drawing process was investigated using high-resolution transmission electron microscopy and molecular dynamics simulation. The excessive thinning of the cementite lamellar thickness observed from the morphology suggested the evolution of the Fe3C/Fe interface in the cold-drawn wires, namely, the partial cementite deformation during the drawing process. Drawing strain played a major role in the occurrence of partial cementite nano-crystallisation. This was because the change in cementite morphology was the primary cause of cementite free energy increase, which ultimately led to cementite phase instability. The decrease of yield strength during the drawing process of the bridge cable steel wire was caused by the inverse Hall-Petch effect resulted from the nodule rotation. When the nodule morphology became flat, the inverse Hall-Petch effect was suppressed. At this time, the strengthening mechanism caused by cementite nano-crystallisation ensured the improvement of tensile strength of steel wire when the dislocation density was close to saturation.