Microscopy Images Research Articles

Graphene–Nickel Oxide–Polyaniline Ternary Nanocomposite‐Embedded Epoxy Coating on Mild Steel for Corrosion Protection

The present work addresses the synthesis and application of graphene‐based ternary nanocomposite for anticorrosion performance to protect mild steel in an accelerated corrosive environment. The chemically‐functionalized graphene‐nickel oxide (Gr‐NiO)‐PANI ternary nanocomposite is synthesized by the hydrothermal reduction of graphene oxide (GO) and nickel salt in the presence of urea, followed by interfacial wrapping of Gr‐NiO by in situ grown polyaniline (PANI). The transmission electron microscopic images reveal the wrapping of Gr‐NiO by PANI in the Gr‐NiO‐PANI ternary nanocomposite. The spectroscopic analyses (Fourier transform infrared and Raman) suggest the multiple interactions between Gr‐NiO and interfacially grown PANI in Gr‐NiO‐PANI. The thoroughly blended Gr‐NiO‐PANI ternary nanocomposite into epoxy matrix via interfacial interactions provides uniform coating (thickness: 87 ± 6 μm) on mild steel and increases the hardness by 160%. The corrosion inhibition performance of PANI, Gr‐PANI, and Gr‐NiO‐PANI nanocomposites in epoxy coating is probed based on electrochemical and salt spray measurements in a 3.5% NaCl solution. The Gr‐NiO‐PANI in the epoxy coating substantially enhances the total impedance and protects the underneath mild steel. The salt spray tests further corroborate the electrochemical results and demonstrate substantial enhancement in corrosion inhibition by Gr‐NiO‐PANI nanocomposite with no sign of corrosion even after 10 days, revealing its potential to mitigate corrosion of mild steel‐based structural and engineering installations.

Acaricidal and insecticidal activities of entomopathogenic nematodes combined with rosemary essential oil and bacterium-synthesized silver nanoparticles against camel tick, Hyalomma dromedarii and wax moth, Galleria mellonella

An innovative approach to ticks and insect pests management is necessary to mitigate the challenges posed by the indiscriminate use of chemical pesticides, which can lead to resistance development and environmental pollution. Despite their great potential, biological control agents have significant manufacturing, application, and stability limitations. Currently, using phytochemicals, biosynthesized nanoparticles, and bioagents to get rid of arthropods might be a good alternative that would make farmers less worried about residues and resistance. The present investigation was carried out to determine for the first time the in vitro acaricidal and insecticidal efficacies of endogenous two entomopathogenic nematodes (EPNs), Heterorhabditis indica and Steinernema sp. combined with either Proteus mirabilis-synthesized silver nanoparticles or Rosmarinus officinalis essential oil against the camel tick, Hyalomma dromedarii larvae and females, and greater wax moth, Galleria mellonella larvae as well. We also determined the potential effects of these treatments on the biological characteristics of H. dromedarii’s engorged females. We further investigated R. officinalis essential oil (EO) profiling and nanoparticle (AgNPs) characterization. All the evaluated combinations demonstrated synergistic effects on the larvae of G. mellonella and H. dromedarii, as well as on engorged females. When H. indica was mixed with EO or AgNPs, it worked well than when Steinernema sp. was mixed with EO or AgNPs. This was shown by the highest number of tick and insect mortalities and the lowest lethal concentration (LC50) values. One day after G. mellonella was exposed to H. indica (1,000 infective juveniles (IJs)) together with EO at 60 or 40 mg/mL, all tested individuals died. We obtained the same results when H. dromedarii females exposed to the same level of EPN with 60 mg/mL EO, and when H. dromedarii larvae treated with H. indica at 500 IJs + EO at 25 mg/mL. Treatments altered all biological parameters of engorged females, revealing extremely noticeable differences between the treated and untreated groups. Gas chromatography–mass spectrometry (GC-MS) analysis identified a total of 28 compounds in the R. officinalis EO. Visual observation showed a color change from yellow to dark brown for AgNPs biosynthesized from P. mirabilis; the transmission electron microscopy (TEM) image and ultraviolet–visible (UV-Vis) spectrum showed well-dispersed particles with a diameter of 5–45 nm; and the greatest surface plasmon peaked at 320 nm. The results demonstrated the high efficacy of combining EPN, H. indica, with EO to control tick and insect pests. This is due to its acaricidal activity on different stages of H. dromedarii, including larvae and engorged females, and its larvicidal effect on G. mellonella.

Cryo-SEM and large volume FIB-SEM of Arabidopsis cotyledons: Degradation of lipid bodies, biogenesis of glyoxysomes and reorganisation of organelles during germination.

Until recently, the lack of three-dimensional visualisation of whole cells at the electron microscopic (EM) level has led to a significant gap in our understanding of the interaction of cellular organelles and their interconnection. This is particularly true with regard to the role of the endoplasmic reticulum (ER). In this study, we perform three-dimensional reconstructions of serial FIB/SEM stacks and anaglyphs derived from volume rendering, cryo-scanning electron microscopy (cryo-SEM) and state-of-the-art electron microscopy immobilisation and imaging techniques. The results show that glyoxysomes are formed de novo in large numbers and in characteristic clusters on the ER upon germination in mesophyll cells of Arabidopsis cotyledons. The degradation of lipid bodies during germination occurs not only via the ER, which enlarges by taking up polar lipids resulting from enzymatic degradation by lipases, but also via glyoxysomes, which engulf lipid bodies. Dictyosomal (Golgi-derived) vesicles, which fuse with glyoxysomes or their precursors, also appear to be involved in the differentiation of glyoxysomes from segments of the ER. The formation of the central vacuole is the result of the fusion of protein storage vacuoles (protein bodies), which become complex three-dimensional structures during germination. Our observations also suggest that the vacuole plays a role in the degradation of glyoxysomes. The evidence provided in three dimensions shows that the endoplasmic reticulum plays a central role in the biogenesis and degradation of lipid bodies, the ontogeny of glyoxysomes and the development of plastids in the mesophyll cells of Arabidopsis cotyledons.

Efficient adsorptive removal of Congo Red dye using activated carbon derived from Spathodea campanulata flowers

This report investigates the preparation, characterization, and application of activated carbon derived from Spathodea campanulata flowers (SCAC) to remove Congo Red (CR) dye from aqueous streams. SCAC was synthesized using orthophosphoric acid activation which yielded a mesoporous material with a specific surface area of (986.41 m2/g), significantly exceeding values reported for flower-derived activated carbons in the available literature. Field emission scanning electron microscopy (FESEM) image revealed an irregular, rough surface morphology pre-adsorption, which became smoother post-adsorption, indicating successful CR attachment. Elemental analysis through energy-dispersive x-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) confirmed an increase in carbon content and the appearance of sulfur, verifying CR uptake. Adsorption kinetics obeyed the pseudo-second-order equation, signifying chemisorption, while the equilibrium dataset fitted better to the Langmuir model, with R2 of 0.9944, suggesting a monolayer adsorption mechanism with a maximum adsorption capacity of 59.27 mg/g. Thermodynamic analysis revealed spontaneous and endothermic adsorption process. Desorption studies showed methanol as the most effective desorbing agent, with SCAC retaining considerable adsorption capacity across six cycles, highlighting its reusability. In tests with real water matrices, SCAC demonstrated significantly higher removal efficiency in natural waters than control, suggesting enhanced adsorption in complex matrices. These findings underscore the practical applicability of SCAC in real-world wastewater treatment, offering a promising solution for large-scale industrial applications.

Interferenceless coded aperture correlation holography for five-dimensional imaging of 3D space, spectrum and polarization

Abstract Interferenceless coded aperture correlation holography (I-COACH) is a robust imaging technique for recovering three-dimensional object information using incoherent holography without two-beam interference. In this study, five-dimensional (5D) imaging along 3D space, spectrum and polarization in I-COACH is proposed and experimentally demonstrated for the first time. The proposed technique exploits the polarization-dependent light modulation characteristics of spatial light modulators to record polarization-dependent intensity distributions, which are distinguished by significant blurring between orthogonal polarization states. 5D I-COACH is implemented by inter-connecting all five dimensions in a single frame, and image recovery is attempted from different configurations of recorded point spread intensity distributions and response-to-object intensity distributions along 5D using recently developed deconvolution techniques. The simulation and experimental results confirm the 5D imaging capabilities of I-COACH. The proposed technique can be a useful tool for birefringence microscopy, and functional and structural imaging applications.

Single-molecule localisation microscopy (SMLM) is feasible in human and animal formalin fixed paraffin embedded (FFPE) tissues in medical renal disease

AimsEstablishment of a protocol for routine single-molecule localisation microscopy (SMLM) imaging on formalin fixed paraffin embedded (FFPE) tissue using medical renal disease including minimal change disease (MCD) and focal segmental...

Impurity-induced step pinning and recovery in MOVPE-grown (100) β-Ga2O3 film

This study focuses on the impact of high-doping impurities (>1018 cm−3) on the morphology of homoepitaxially grown (100) 4° off β-Ga2O3 film, as well as incorporating insights from the Cabrera–Vermilyea model (C–V model). Using atomic force microscopy imaging, we reveal that under low-supersaturation conditions, dopant-induced impurities lead to irregular step formation and growth stalling, inducing the step-bunching formation consistent with C–V model predictions. Conversely, higher supersaturation conditions restore desired step-flow morphology, resembling low-impurity growth states. It is also shown that the step-bunching formed under lower supersaturation conditions and high-impurity concentration might induce unwanted structural defects and compensate the free carriers. These findings underscore the delicate interplay between dopant concentrations, growth morphology, and supersaturation in metalorganic vapor phase epitaxy-grown (100) β-Ga2O3 films, providing a comprehensive understanding of optimizing their electrical properties with respect to power electronics applications.

Evaluation of safe exposure time for two-photon microscopy imaging of acrylic-painted mock-ups

Abstract Nonlinear optical microscopies are widely used in the biological and biomedical fields, as they are non-invasive techniques that permit the safe structural and morphological characterisation of cells and tissues. They are increasingly being used in the Cultural Heritage field because of their ability to overcome some limits of the well-established optical techniques. However, since nonlinear optical microscopies use pulsed laser sources with high peak power, their application in Cultural Heritage raises concerns due to artworks' unique, priceless, and delicate nature. In this paper, we present a new method for evaluating the photo-induced damage when using a near-infrared femtosecond pulsed laser to perform two-photon excited fluorescence imaging of acrylic-painted mock-ups. In particular, we explore herein several irradiation conditions, varying the exposure time and excitation power, in order to provide useful experimental indications for safely imaging acrylic paints with two-photon microscopy.

Lattice Multislice Algorithm for Fast Simulation of Scanning Transmission Electron Microscopy Images.

We introduce a new approach to the numerical simulation of Scanning Transmission Electron Microscopy images. The Lattice Multislice Algorithm takes advantage of the fact that the electron waves passing through the specimen have limited bandwidth and therefore can be approximated very well by a low-dimensional linear space spanned by translations of a well-localized function. Just like in the PRISM algorithm recently published by C. Ophus, we utilize the linearity of the Schrödinger equation but perform the approximations with functions that are well localized in real space instead of Fourier space. This way, we achieve a similar computational speedup as PRISM, but at a much lower memory consumption and reduced numerical error due to avoiding virtual copies of the probe waves interfering with the result. Our approach also facilitates faster recomputations if local changes are made to the specimen such as changing a single atomic column.

A guide to CNN-based dense segmentation of neuronal EM images.

Large-scale reconstitution of neuronal circuits from volumetric electron microscopy images is a remarkable research goal in neuroanatomy. However, the large-scale reconstruction is a result of automatic segmentation using convolutional neural networks (CNNs), which is still challenging for general researchers to perform. This review focuses on two representative CNNs for dense neuronal segmentation: flood-filling networks (FFN) and local shape descriptors (LSD)-predicting U-Net (LSD network). It outlines their basic mechanisms, requirements, and output segmentation using author's example segmentation. The FFN excels in segmenting long axons, and the LSD network is adept at segmenting myelinated axons. The choice between FFN and LSD depends on the target, as neither is universally superior. A common limitation of FFN and LSD is the easy detachment of thin spines from parent dendrites, which is fundamentally unavoidable. The author also introduces CNNs proposed to mitigate this issue. As CNN-based automated segmentation can take months, researchers need to be aware of the selection of an appropriate CNN, required computer resources, and fundamental limitations. This review serves as a guide for such dense neuronal segmentation.

Zinc Oxide Nanoparticle Loaded L-Carnosine Biofunctionalized Polyacrylonitrile Nanofibrous Wound Dressing for Post-Surgical Treatment of Melanoma

Nanofibrous dressing materials with an antitumor function can potentially inhibit recurrence of melanoma following the surgical excision of skin tumors. In this study, hydrolyzed polyacrylonitrile (hPAN) nanofibers biofunctionalized with L-carnosine (CAR) and loaded with bio (CAR)-synthesized zinc oxide (ZnO) nanoparticles, ZnO/CAR-hPAN (hereafter called ZCPAN), were employed to develop an antimelanoma wound dressing. Inspired by the formulation of the commercial wound healing Zn-CAR complex, i.e., polaprezinc (PLZ), for the first time, we benefitted from the synergy of zinc and CAR to create an antimelanoma nanofibrous wound dressing. According to scanning electron microscopy (SEM) images, ultrafine ZnO nanoparticles were homogenously distributed throughout the nanofibrous dressing. The ZCPAN nanofiber mat showed a significantly higher toughness (18.7 MJ.m−3 vs. 1.4 MJ.m−3) and an enhanced elongation at break (stretchability) compared to the neat PAN nanofiber mat (12% vs. 9.5%). Additionally, optical coherence elastography (OCE) measurements indicated that the ZCPAN nanofibrous dressing was as stiff as 50.57 ± 8.17 kPa which is notably larger than that of the PAN nanofibrous dressing, i.e., 24.49 ± 6.83 kPa. The optimum mechanical performance of the ZCPAN nanofibers originates from physicochemical interaction of CAR ligands, hPAN nanofibers, and ZnO nanoparticles through hydrogen bonding, electrostatic bonding, and esterification, as verified using ATR-FTIR. An in vitro cell viability assay using human skin melanoma cells implied that the cells are notably killed in the presence of the ZCPAN nanofibers compared to the PAN nanofibers. Thanks to ROS generating ZnO nanoparticles, this behavior originates from the high reactive oxygen species (ROS)-induced oxidative damage of melanoma cells, as verified through a CellROX assay. In this regard, an apoptotic cell response to the ZCPAN nanofibers was recorded through an apoptosis assay. Taken together, the ZCPAN nanofibers induce an antimelanoma effect through oxidative stress and thus are a high potential wound dressing material to suppress melanoma regrowth after surgical excision of skin tumors.

Effect of non-spherical shape of dry powder aerosol drugs on their airway deposition distribution.

In the majority of aerosol drug deposition modelling efforts, the particles are approximated by regular spheres. However, microscope images acquired after drug formulation available in the open literature suggest that their shape is not regular in most cases. This work aimed to combine experimental measurements and numerical simulations to reveal the shape factors of the particles of commercialized aerosol drugs and the effect of non-sphericity on the lung deposition distribution of these drugs. Aerosol particles of Bretaris® Genuair®, Buventol® Easyhaler® and Trelegy® Ellipta® were collected on the stages of a Next Generation Impactor after their emission from the dry powder inhalers. The samples were analyzed using scanning electron microscopy techniques. Aspect ratios and dynamic shape factors characteristic of particles in the size fractions representing each impactor stage were determined. Computer modelling of their airway deposition was performed by both neglecting and considering their irregular shape. The results of particle size measurements revealed that there was no size-specific shape factor of the particles, as they could be well characterized by a global shape factor. Although there was some inter-drug difference in terms of shape factors, the values were quite close to unity (usually between 1.02 and 1.06), except for the fiber-shaped particles representing a minority in the composition of Trelegy® Ellipta®, which could be characterized by shape factors of around 1.6. The results of computer simulations of deposition distribution indicate that neglecting the irregular shape does not lead to a major distortion of the simulation results unless fiber-shaped particles are also present after the formulation.

Developing affordable and efficient heating devices for enhanced live cell imaging in confocal microscopy

Developing affordable and efficient heating devices for enhanced live cell imaging in confocal microscopy

Benthic Foraminifera and Diatom Relationship: Insights from RbcL Gene Sequences in Palk Bay

Understanding the symbiotic relationships between benthic foraminifera and diatoms is crucial for ecological studies, particularly in environmental changes. In this study, DNA barcoding, targeting the rbcL gene, was applied to identify diatoms and evaluate their diversity within the foraminiferal shells in Thondi, Palk Bay. Foraminifera were isolated from the sediment samples collected using grab samplers at six different locations. The separated benthic foraminifera were then used for DNA barcoding. The obtained DNA sequences were aligned and analyzed comprehensively using Geneious Pro v5.1. A higher population of Ammonia parkinsoniana was observed in March 2023 compared to May 2023, with a notable presence of algal symbionts. Seasonal temperature fluctuations exhibited a strong positive influence on the abundance of A. parkinsoniana. Changes in salinity and temperature were suggested to induce species shifts within the intertidal foraminiferal community. The symbiotic diatoms within the A. parkinsoniana shells were confirmed through rbcL gene sequencing and Scanning Electron Microscope (SEM) imaging. Phylogenetic analysis indicated a 50% similarity between the foraminifera and diatoms. SEM imagery displayed diatoms attached to the surface of A. parkinsoniana cells, while Energy Dispersive X-ray (EDX) analysis detected silica content at the diatom sites. This study highlights the potential of DNA barcoding to identify and develop novel chloroplast markers to elucidate foraminiferal symbiotic relationships.

Nano-viscosimetry analysis of membrane disrupting peptide magainin2 interactions with model membranes.

The rapid spread of antibiotic-resistant strains of bacteria has created an urgent need for new alternative antibiotic agents. Membrane disrupting antimicrobial peptides (AMPs): short amino acid sequences with bactericidal and fungicidal activity that kill pathogens by permeabilizing their plasma membrane may offer a solution for this global health crisis. Magainin 2 is an AMP secreted by the African clawed frog (Xenopus laevis) that is described as a toroidal pore former membrane disrupting AMP. Magainin 2 is one of the most thoroughly studied AMPs, yet its mechanism of action is still largely hypothetical: visual evidence of the pore formation is lacking, and the molecular mechanism leading to pore formation is still debated. In the present study, quartz crystal microbalance (QCM) based viscoelastic fingerprinting analysis supported by dye leakage experiments and atomic force microscopy (AFM) imaging was used to glean deeper insights into the mechanism of action. The effect of membrane charge, acyl chain unsaturation and cholesterol concentration were also investigated. The results show lipid specific disruptive mechanism of magainin 2. QCM nano-viscometry measurements revealed the presence of distinct stages in the mechanism of magainin 2 action that, with dye leakage data, confirm the existence of an initial transient pore stage that may result in peptide flip-flop between the outer and inner membrane leaflets. There is evidence of a further mechanistic stage at high peptide concentrations that is consistent with membrane collapse into a peptide-lipid mixed phase that is distinct from the transient pore formation. The results confirm some of the earliest hypotheses about magainin 2 action, while also highlighting the membrane modulating effect of this peptide.

Raman Signature of Stripe Domains in Monolayer WxMo1-xS2 Alloys.

We study the Raman signature of stripe domains in monolayer WxMo1-xS2 alloys, characterized using experimental techniques and density functional theory (DFT) calculations. These stripe domains were found in star-shaped monolayer WS2 exhibiting a high concentration of molybdenum (Mo) atoms in its central region, and unique Raman peaks that were not previously reported. We attribute these peaks to the splitting of the original doubly degenerate E2g modes, arising from the lower symmetry of the W-Mo stripe domains. We confirm the stripe presence and location using high-resolution scanning transmission electron microscopy (STEM) imaging and use DFT to elucidate the structural, electronic, and vibrational properties of the stripes when the stoichiometry corresponds to W0.5Mo0.5S2. The findings provide insight into the evolution of the Raman spectra as stripe domains arise in TMD alloys, thus contributing to a broader understanding of the influence of atomic-level structural modifications on material properties.

High-Density Polyethylene–Polypropylene Blends: Examining the Relationship Between Nano/Microscale Phase Separation and Thermomechanical Properties

The phase separation of high-density polyethylene (HDPE)–polypropylene (PP) blends was studied using atomic force microscopy in tapping mode to obtain height and phase images. The results are compared with those from scanning electron microscopy imaging and are connected to the thermomechanical properties of the blends, characterised through differential scanning calorimetry, dynamic mechanical analysis (DMA), and tensile testing. Pure PP, as well as 10:90 and 20:80 weight ratio HDPE–PP blends, showed a homogeneous morphology, but the 25:75 HDPE–PP blends exhibited a sub-micrometre droplet-matrix structure, and the 50:50 HDPE–PP blends displayed a more complex co-continuous nano/microphase-separated structure. These complex phase separation morphologies correlate with the increased loss modulus (viscous properties) of the corresponding blends as measured by DMA, demonstrating the potential for the creation of strong and simultaneously tough, energy-absorbing materials for numerous applications.

Electrically Switchable Multi-Stable Topological States Enabled by Surface-Induced Frustration in Nematic Liquid Crystal Cells.

In liquid crystal (LC) cells, the surface patterning directs the self-assembly of the uniaxial building blocks in the bulk, enabling the design of stimuli-response optical devices with various functionalities. The combination of different anchoring patterns at both substrates can lead to surface induced frustration, preventing a purely planar and defect-free configuration. In cells with crossed assembly of rotating anchoring patterns, elastic deformations allow to obtain a defect-free bulk configuration, but an electrical stimulus can induce disclination lines. The disclination network is preserved without applied voltage. Depending on the electric field treatment and geometrical parameters, different multi-stable states with and without disclinations are obtained. This is demonstrated with the help of dual-frequency LCs, for which the frequency dependent dielectric properties allow repeatable switching between multi-stable states. Topological protection and the associated energy barrier between different states explains the observed metastability. The obtained configurations are retrieved with Q-tensor simulations and the validity is confirmed by matching optical simulations with experimentally obtained microscopy images. The realized multi-stable topological states interact differently with light, resulting in distinct optical properties. Optimization allows to switch between a highly transparent state and an opaque state, opening up opportunities for smart windows with low energy consumption.

Precise Sizing and Collision Detection of Functional Nanoparticles by Deep Learning Empowered Plasmonic Microscopy.

Single nanoparticle analysis is crucial for various applications in biology, materials, and energy. However, precisely profiling and monitoring weakly scattering nanoparticles remains challenging. Here, it is demonstrated that deep learning-empowered plasmonic microscopy (Deep-SM) enables precise sizing and collision detection of functional chemical and biological nanoparticles. Image sequences are recorded by the state-of-the-art plasmonic microscopy during single nanoparticle collision onto the sensor surface. Deep-SM can enhance signal detection and suppresses noise by leveraging spatio-temporal correlations of the unique signal and noise characteristics in plasmonic microscopy image sequences. Deep-SM can provide significant scattering signal enhancement and noise reduction in dynamic imaging of biological nanoparticles as small as 10nm, as well as the collision detection of metallic nanoparticle electrochemistry and quantum coupling with plasmonic microscopy. The high sensitivity and simplicity make this approach promising for routine use in nanoparticle analysis across diverse scientific fields.

Virtual Gram staining of label-free bacteria using dark-field microscopy and deep learning.

Gram staining has been a frequently used staining protocol in microbiology. It is vulnerable to staining artifacts due to, e.g., operator errors and chemical variations. Here, we introduce virtual Gram staining of label-free bacteria using a trained neural network that digitally transforms dark-field images of unstained bacteria into their Gram-stained equivalents matching bright-field image contrast. After a one-time training, the virtual Gram staining model processes an axial stack of dark-field microscopy images of label-free bacteria (never seen before) to rapidly generate Gram staining, bypassing several chemical steps involved in the conventional staining process. We demonstrated the success of virtual Gram staining on label-free bacteria samples containing Escherichia coli and Listeria innocua by quantifying the staining accuracy of the model and comparing the chromatic and morphological features of the virtually stained bacteria against their chemically stained counterparts. This virtual bacterial staining framework bypasses the traditional Gram staining protocol and its challenges, including stain standardization, operator errors, and sensitivity to chemical variations.