Advanced Microscopy Techniques Research Articles

An antibiotic efficacy comparative study between market-prescribed and solid-lipid fluoroquinolone ophthalmic nanoformulation against conjunctivitis

Besifloxacin hydrochloride (BSF) drug substance (DS), is effective against gram-positive and gram-negative microorganisms. BSF (liquid suspension form) is already available in two different market brands: Besivance and Besix. Both of these commercialized drug products (DP) have lower mucoadhesive characteristics, therefore they spend less time in contact with various ocular tissues (cornea and conjunctiva). This research work emphasized the design, development, and optimization of BSF-loaded solid-lipid nanoparticles (BSF@SLN) to increase antibacterial activity by enhancing drug absorption through passive diffusion techniques in the ocular organ compared to conventional dosage forms. The SLN was prepared through a very simple process hot homogenization process using glyceryl monostearate and polysorbate-80 along with poloxamer-188 and water for injection. Various characterization techniques like FTIR, DSC, and XRD were performed to check the compatibility between DS and excipients. The preliminary formulation of SLN was characterized through zeta potential, polydispersity index, and particle size techniques. The developed SLN was optimized following 32 factorial designs. Surface morphology and size of optimized BSF@SLN ophthalmic DP were confirmed by using advanced microscopic techniques such as SEM. In-vitro release of optimized BSF@SLN ophthalmic DP was performed by using two chambers of Franz diffusion cell. Stability studies of optimized BSF@SLN ophthalmic nanoformulations were tested for up to 6 months at 25°C ± 2°C/60% ± 5% RH. The antimicrobial activity of optimized ophthalmic nanoformulation was found 2.76 times more effective compared to the Besix eye drop. In-vivo study of BSF@SLN ophthalmic nanoformulations was carried out with an eye irritancy test and compared with marketed DP (Besix). and found significant pharmacological.

Speed-dependent bacterial surface swimming.

In the early phase of biofilm formation, bacteria identify surfaces and increase the intracellular level of the second messenger c-di-GMP, resulting in a decrease in swimming speed. Here, we utilized advanced microscopy techniques to investigate the impact of swimming speed on bacterial surface swimming, focusing on Escherichia coli and Pseudomonas aeruginosa. We found that an increase in swimming speed led to an increase in the radius of curvature and a decrease in surface detention time. These effects were explained through hydrodynamic modeling as a result of an increase in the cell-surface distance with increasing swimming speed. We also observed distinct surface-escaping mechanisms between the two bacterial species. Our study suggests that a decrease in swimming speed could enhance the likelihood of cells adhering to the surface, promoting biofilm formation. This sheds light on the role of reduced swimming speed in the transition from motile to sedentary bacterial lifestyles.

Shining insights: Deciphering the biogenic synthesis of Ajuga bracteosa-mediated gold nanoparticles with advanced microscopy techniques.

In this study, gold nanoparticles (AuNPs) were bioreduced from Ajuga bracteosa, a medicinal herb known for its therapeutic properties against various diseases. Different fractions of the plant extract were used, including the methanolic fraction (ABMF), the n-hexane fraction (ABHF), the chloroform fraction (ABCF), and the aqueous extract for AuNPs synthesis. The characterization of AuNPs was performed using UV-Vis spectrophotometry, FT-IR, XRD, EDX, and TEM. UV-Vis spectroscopy confirmed the formation of AuNPs, with peaks observed at 555 nm. FT-IR analysis indicated strong capping of phytochemicals on the surface of AuNPs, which was supported by higher total phenolic contents (TPC) and total flavonoid contents (TFC) in AuNPs. XRD results showed high crystallinity and a smaller size distribution of AuNPs. TEM analysis revealed the spherical shape of AuNPs, with an average size of 29 ± 10 nm. The biologically synthesized AuNPs exhibited superior antibacterial, antioxidant, and cytotoxic activities compared to the plant extract fractions. The presence of active biomolecules in A. bracteosa, such as neoclerodan flavonol glycosides, diterpenoids, phytoecdysone, and iridoid glycosides, contributed to the enhanced biological activities of AuNPs. Overall, this research highlights the potential of A. bracteosa-derived AuNPs for various biomedical applications due to their remarkable therapeutic properties and effective capping by phytochemicals. RESEARCH HIGHLIGHTS: This research underscores the growing significance of herbal medicine in contemporary healthcare by exploring the therapeutic potential of Ajuga bracteosa and gold nanoparticles (AuNPs). The study highlights the notable efficacy of A. bracteosa leaf extracts and AuNPs in treating bacterial infections, demonstrating their bactericidal effects on a range of strains. The anti-inflammatory properties of plant extracts and nanoparticles are evidenced through paw edema method suggesting their applicability in managing inflammatory conditions. These findings position A. bracteosa and AuNPs as potential candidates for alternative and effective approaches to modern medication.

Visualizing Structure, Growth, and Dynamics of Li Dendrite in Batteries: From Atomic to Device Scales

AbstractThe growth of lithium (Li) dendrites, characterized by construction of internal Li substrate and surface solid electrolyte interphase (SEI), represents a significant hurdle for both liquid‐state and solid‐state Li batteries. To better understand the growth behaviors of these dendrites at atomic to device scale, advanced electron microscopy techniques have emerged as a valuable tool, providing high temporal and spatial resolutions for real‐time observations. In this review, the mechanistic aspects of growth of Li dendrites are delved first from both thermodynamic and kinetic perspectives. Then, a systematic overview of the state‐of‐the‐art in‐situ devices is provided that is developed for integration into electron microscopes, detailing the corresponding static and dynamic structures of Li dendrites. Additionally, the utilization of the non‐destructive cryogenic TEM technique is explored to classify and compare the local fine structure information of as‐formed Li deposits, which are influenced by various factors such as current density, temperature, electrolyte composition, solvents, and additives. Overall, this review article offers a comprehensive understanding of the physical origins associated with Li dendrites, spanning from atomic to device scales and encompassing both liquid and all‐solid‐state battery scenarios, then envisioning fundamental principles and strategies for optimizing batteries and overcoming the critical challenges posed by Li dendrites.

Investigating Pitting Behavior of Stainless-Steel for Canister in Vertical Position Using Electrochemical Acceleration Test

Stainless steel is renowned for its corrosion resistance and is widely used in constructing canisters for nuclear waste containment. These canisters are designed to endure burial in soil for over a century, making it crucial to study the long-term corrosion behavior of SS in this specific context. However, analysis of the corrosion behavior of SS is challenging due to its slow corrosion rate. Therefore, electrochemical acceleration methods are essential in studying the corrosion behavior of SS. This research employs the potentiostatic polarization test to comprehensively analyze SS pitting corrosion. The study focuses on vertically-positioned SS specimens, simulating canister conditions. Advanced microscopy techniques and simulation aid in understanding anolyte, pit depth, and pit shape behavior. Through this, the pitting propagation process of SS could be divided into four stages. Key outcomes of this study include models for absolute depth during propagation and the formation of secondary pitting. Comparative analysis with immersion tests reveals insights crucial for industrial installations safety and longevity.

Noninvasive diagnostic biomarkers, genomic profiling, and advanced microscopic imaging in the early detection and characterization of Naegleria fowleri infections leading to primary amebic meningoencephalitis (PAM).

This review delves into the strategies for early detection and characterization of Naegleria fowleri infections leading to primary amoebic meningoencephalitis (PAM). The study provides an in-depth analysis of current diagnostic approaches, including cerebrospinal fluid analysis, brain tissue examination, immunostaining techniques, and culture methods, elucidating their strengths and limitations. It explores the geographical distribution of N. fowleri, with a focus on regions near the equator, and environmental factors contributing to its prevalence. The review emphasizes the crucial role of early detection in PAM management, discussing the benefits of timely identification in treatment, personalized care, and prevention strategies. Genomic profiling techniques, such as conventional PCR, nested PCR, multiplex PCR, and real-time PCR, are thoroughly examined as essential tools for accurate and prompt diagnosis. Additionally, the study explores advanced microscopic imaging techniques to characterize N. fowleri's morphology and behavior at different infection stages, enhancing our understanding of its life cycle and pathogenic mechanisms. In conclusion, this review underscores the potential of these strategies to improve our ability to detect, understand, and combat N. fowleri infections, ultimately leading to better patient outcomes and enhanced public health protection.

Mechanical characterization of materials using advanced microscopy techniques

This review explores the synergistic relationship between advanced microscopy techniques and mechanical engineering, outlining their profound impact on materials science and mechanical system design. We delve into the multifaceted applications of electron microscopy, X-ray diffraction, and spectroscopic methods in understanding microstructural dynamics, mechanical properties, and failure mechanisms of materials integral to mechanical engineering. Through a comprehensive synthesis of recent research, we emphasize the pivotal role these techniques play in optimizing material performance, bolstering structural integrity, and driving innovation in mechanical design. By elucidating the intricate details of material behavior at the microscale, advanced microscopy contributes to informed decision-making in material selection and design processes. Furthermore, we address emerging trends and prospects, underscoring the continued synergy between advanced microscopy and mechanical engineering. This collaboration remains at the forefront of materials science and technology, promising ongoing advancements that will shape the future landscape of mechanical design and materials innovation.

Recent progress about transmission electron microscopy characterizations on lithium-ion batteries

With the rapid development of portable electronics, new energy vehicles, and smart grids, ion batteries are becoming one of the most widely used energy storage devices, while the safety concern of ion batteries has always been an urgent problem to be solved. To develop a safety-guaranteed battery, the characterization of the internal structure is indispensable, where electron microscopy plays a crucial role. Based on this, this paper summarizes the application of transmission electron microscopy (TEM) in battery safety, further concludes and analyzes the aspects of dendrite growth and solid electrolyte interface (SEI) formation that affect the safety of ion batteries, and emphasizes the importance of electron microscopy in battery safety research and the potential of these techniques to promote the future development of this field. These advanced electron microscopy techniques and their prospects are also discussed.

Spectroscopic Analysis of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-COV-2)

Abstract: When light shines on an object, it sheds focus on the intrinsic characteristics of that material. Transmission of light or an electromagnetic (em) wave through a matter undergoes various physiochemical processes, like emission, absorption, and splitting of light into its constituent wavelengths. This interaction of em radiation with matter is widely used for the investigation of unknown and new target analytes in a sample, and the technique is known as spectroscopy. In the early 2000s, energy excitation of the virus was demonstrated in influenza. The research first demonstrated the use of Surface-enhanced Raman Scattering (SERS), whose biomedical application became a potential diagnostic tool. The LASERs also attracted attention and were incorporated with the optical and spectroscopy instruments that significantly enhanced the application, reach, and detection limit of air and waterborne elements. Surface plasmon resonance and SERS are the most applied spectroscopic techniques with high accuracy and speed. A combination of these techniques with other advanced microscopy techniques, such as atomic force microscopy, scanning electron microscopy, and tunnelling electron microscopy, may ease and boost biomedical applications. This review is focused on the application of spectroscopy and laser-based techniques in the detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-COV-2).

On wear of TiAlN coated tools with and without NbN overlayer in machining titanium alloys

Finding a wear resistant coating for cemented carbide cutting tools in the machining of difficult to cut Ti alloys is a challenge due to their high strength and chemical reactivity. Tool manufacturers recommend physical vapor deposited (PVD) TixAl1-xN (x = 0.4–0.7), and an extra NbN overlayer has shown promising potential. This study explores wear mechanisms of PVD Ti0.45Al0.55N with and without NbN overlayer and its WC-Co substrate in machining Ti alloys. To achieve an accurate understanding of tool-chip-workpiece interaction and related wear mechanisms, several approaches were employed. Tests with controlled variation of cutting speeds were complemented by process freezing experiments using the quick stop method and imitational experiments of diffusion couples. Advanced microscopy techniques were employed for accurate detection of wear products and phenomena across length scale. Findings reveal that any new design of coatings for Ti machining must combine both high mechanical integrity and resistance to diffusional dissolution and oxidation. Observed diffusional loss of Al and N from the coating results in a TiN layer which is mechanically weaker than the original coating, while the NbN overlayer reduces the Al diffusion rate, but NbN is subjected to diffusional dissolution itself. On dissolution, Nb stabilizes β-Ti and thus facilitating loss of Al, but the observed formation of intermetallic Nb3Al at the NbN–Ti interface works as a diffusion barrier. However, brittle Nb3Al can be more easily removed during machining. It was found that the coating retains longest on the edge line and protects the tool edge from failure because substrate cemented carbide wears at a faster rate than the coating with outward diffusion of C from WC grains and Co binder.

Nuclear actin dynamics and functions at a glance.

Actin is well known for its cytoskeletal functions, where it helps to control and maintain cell shape and architecture, as well as regulating cell migration and intracellular cargo transport, among others. However, actin is also prevalent in the nucleus, where genome-regulating roles have been described, including it being part of chromatin-remodeling complexes. More recently, with the help of advances in microscopy techniques and specialized imaging probes, direct visualization of nuclear actin filament dynamics has helped elucidate new roles for nuclear actin, such as in cell cycle regulation, DNA replication and repair, chromatin organization and transcriptional condensate formation. In this Cell Science at a Glance article, we summarize the known signaling events driving the dynamic assembly of actin into filaments of various structures within the nuclear compartment for essential genome functions. Additionally, we highlight the physiological role of nuclear F-actin in meiosis and early embryonic development.

Microstructure-properties relation of hydrostatically extruded absorbable zinc alloys: Effect of Mg and Cu addition on corrosion properties and biocompatibility

Pure Zn is well-known for its appropriate corrosion rate, making it suitable for use as future absorbable implants. Yet, it suffers from insufficient strength, thus, both plastic deformation and alloying are required. Hydrostatic extrusion has proven to be an efficient technique, providing high mechanical properties for zinc alloys. However, its effect on degradation rate and biocompatibility of Zn alloys remains unknown. Thus, within the present study, an attempt to evaluate those properties has been made on hydrostatically extruded pure Zn, Zn–Mg and Zn–Mg–Cu alloys. The materials were characterized by advanced microscopy techniques and uniaxial tensile tests. Corrosion properties were assessed based on electrochemical and static immersion tests. Finally, the cytotoxic effect of zinc extracts on endothelial cells were examined by standard MTT assays combined with confocal imaging.The results showed that hydrostatic extrusion results in significant refinement of α-Zn grains and the intermetallic phase Mg2Zn11 for the investigated alloys. The alloys exhibited ultimate tensile strength exceeding 300 MPa and elongation higher than 20%. Corrosion tests demonstrated that all the materials showed a similar level of degradation rate. Moreover, the uniform distribution of the intermetallic phase contributed to homogeneous corrosion of Zn alloys. Biological studies indicated that the least cytotoxic response in endothelial cells was obtained for the Zn–Mg alloy. Such an effect was caused by the limited amount of released Zn ions in the favor of Mg ions.The refinement of α-Zn grains and intermetallic phases caused by hydrostatic extrusion were key factors determining the performance of Zn-based materials.

Aluminum enhances the oxidative damage of ZnO NMs in the human neuroblastoma SH-SY5Y cell line

Bare and doped zinc oxide nanomaterials (ZnO NMs) are of great interest as multifunctional platforms for biomedical applications. In this study, we systematically investigate the physicochemical properties of Aluminum doped ZnO (AZO) and its bio-interactions with neuroblastoma (SH-SY5Y) and red blood (RBCs) cells. We provide a comprehensive chemical and structural characterization of the NMs. We also evaluated the biocompatibility of AZO NMs using traditional toxicity assays and advanced microscopy techniques. The toxicity of AZO NMs towards SH-SY5Y cells, decreases as a function of Al doping but is higher than the toxicity of ZnO NMs. Our results show that N-acetyl cysteine protects SH-SY5Y cells against reactive oxygen species toxicity induced by AZO NMs. ZnO and AZO NMs do not exert hemolysis in human RBCs at the doses that cause toxicity (IC50) in neuroblastoma cells. The Atomic force microscopy qualitative analysis of the interaction of SH-SY5Y cells with AZO NMs shows evidence that the affinity of the materials with the cells results in morphology changes and diminished interactions between neighboring cells. The holotomographic microscopy analysis demonstrates NMs' internalization in SH-SY5Y cells, changes in their chemical composition, and the role of lipid droplets in the clearance of toxicants.Graphical

A Study of Porous Activated Carbon Anodes for High-Performance Lithium-Ion Batteries

This research paper explores the intricate realm of porous activated carbon anodes for high-performance lithium-ion batteries, responding to the escalating demand for advanced energy storage systems. The study begins by delving into various synthesis methods, including physical and chemical activation, and hybrid approaches, aiming to optimize porosity and surface chemistry. Detailed investigations into structural characteristics encompass surface area, pore distribution, morphology, and surface chemistry. Advanced microscopy techniques and characterization tools provide insights into the complex interplay between structural features and electrochemical performance. Moving beyond the laboratory, the paper explores potential applications of porous activated carbon anodes. In electric vehicles, these anodes demonstrate promise in enhancing energy and power density, critical factors for the widespread adoption of electric transportation. For portable electronic devices, the lightweight nature and improved safety profile make them an attractive choice. Additionally, the study assesses the feasibility of integrating porous activated carbon anodes in grid-scale energy storage, contributing to the stability and reliability of renewable energy integration. Environmental considerations are addressed, evaluating the sustainability and recyclability of porous activated carbon anodes. The paper concludes by summarizing key findings, emphasizing the significance of porous activated carbon in advancing lithium-ion battery technology, and proposing future research directions to overcome current challenges. The extensive array of references underscores the interdisciplinary nature of the research, incorporating a diverse range of sources to provide a comprehensive overview of the field.

Investigation on different materials after pulsed high field conditioning and low-energy H- irradiation

During operation, the radio-frequency quadrupole (RFQ) of the LINAC4 at CERN is exposed to high electric fields, which can lead to vacuum breakdown. It is also subject to beam loss, which can cause surface modification, including blistering, which can result in reduced electric field holding and an increased breakdown rate. First, experiments to study the high-voltage conditioning process and electrical breakdown statistics have been conducted using pulsed high-voltage DC systems in order to identify materials with high electric field handling capability and robustness to low-energy irradiation. In this paper, we discuss the results obtained for the different materials tested. To complement these, an investigation of their metallurgical properties using advanced microscopic techniques was done to observe and characterize the different materials and to compare results before and after irradiation and breakdown testing.

Directly Identifying Multiple Cr3+ Emitting Centers for Broad Near‐Infrared Emission in an Efficient and Near‐Zero Thermal Quenching Garnet‐Type Phosphor

AbstractCr3+ doped garnet‐type (A3B2C3O12) near‐infrared (NIR) phosphors is a desirable research hotspot due to their prospective night vision, bioimaging, and plant growth utilizations. Meanwhile, the origin of multisite broad emission is yet a controversial topic. To resolve the trouble, verifying accurately the multiple Cr3+ occupancy sites is a key. Furthermore, it is an urgent need for improving the external quantum efficiency and luminescent thermostability. Herein, in Y3Sc2Al3O12 (YSAO), advanced electron microscopy technique is employed to directly confirm that the obtained broadband NIR emission originates from Cr3+ in [ScO6] octahedral and [YO8] dodecahedral sites. The optimal YSAO:5%Cr3+ sample exhibits high quantum efficiency (IQE/EQE = 74/31%) and near‐zero thermal quenching (97%@423 K and 92%@473 K). The theoretical calculations and experimental proofs reveal that YSAO possesses high structural rigidity and wide bandgap, which is responsible for the extremely thermostable luminescence. The high‐power YSAO:5%Cr3+‐converted NIR LED device shows promising multifunctional applications. This work not only provides an efficient NIR broadband phosphor with near‐zero thermal quenching, but also provides an effective determination method for the multiple emitting centers of phosphor materials.

Diversity of Complex Organic Matter in Carbonaceous Chondrites, IDPs, and UCAMMs

Complex organic matter is present in many extraterrestrial materials such as chondrite meteorites, micrometeorites, and interplanetary dust. The observed complexity of this organic matter is due to the combination of diversity of primitive organic materials that accreted onto asteroids and the subsequent effect of hydrothermal and/or metamorphic alteration that took place after accretion. These processes resulted in a variety of carbonaceous grain morphologies, elemental abundances, and organic functional group compositions. Some carbonaceous dust grains and micrometeorites have cometary origins and provide insights into the unique processing histories on those outer Solar System bodies. Isotopic analyses can help distinguish carbonaceous grains that retain their pre-accretion heritage, while advanced microscopy techniques reveal the interplay of complex organic matter with surrounding mineral.

Simple and facile synthesis of single-crystal CeO2 abrasives and its highly efficient removal mechanism on SiO2 film

CeO2 nanoparticles are one of the key abrasives for chemical mechanical polishing (CMP) in advanced integrated circuits. However, synthesizing highly chemically reactive CeO2 often involves ion doping, high-temperature calcination or reduction, which increase cleaning challenges and risk scratching wafers. We developed a simple and facile method for synthesizing single-crystal CeO2. It exhibits superior polishing performance compared to commercial CeO2, with the material removal rate (MRR) increasing to 4141.45 from 3649.99 Å/min and the surface roughness (Sa) decreasing to 0.533 from 0.647 nm. The CeO2 abrasives were characterized by X-ray Diffraction (XRD), advanced microscopy techniques (SEM, TEM), X-ray Photoelectron Spectroscopy (XPS), and Hydrogen Temperature-Programmed Reduction (H2-TPR). It revealed that the synthesized CeO2 has a particle size of approximately 60 nm and its surface was covered with a uniform amorphous layer of ∼ 1 nm. XPS and H2-TPR revealed its high Ce3+ concentration and enhanced oxygen exchange capability. The polishing mechanism was investigated by XPS and High-Resolution TEM (HR-TEM). Under pressure, the CeO2 established Ce-O-Si bonds with the SiO2 surface. Ce3+ provided electrons to the antibonding orbitals of Si-O bonds, effectively breaking stable Si-O bonds and removed SiO2 film in the form of lump SiO2 through mechanical action.

Investigation of the Changes in the Hair Cuticle Due to Chemical Degradation

Various cosmetic alterations done to the hair for aesthetic purposes have a profound damaging impact on its morphology. This study delves into the complex dynamics of hair structure by analysing the changes in the cuticle induced by chemical degradation. Advanced microscopic techniques like Microtopography and Scanning Electron Microscopy (SEM) were employed to investigate the grade of damage on treated hair as compared with virgin hair. On treatment with bleach, it could be observed that the cuticle structure in virgin hair exhibited deteriorating effects like partial degradation whereas the impact on treated hair samples strands that had previously undergone modifications exhibited much more intensifying consequences like complete deterioration exposing holes and gaps. The findings from the current exploration shed light on the nuanced relationships within the hair structure, providing valuable insights into the consequences of chemical degradation. Thus, laying a foundation for suggestive recommendations that include the impact of environment, lifestyle and genetics in the fields of trichology and cosmetology.

Visualisation of microalgal lipid bodies through electron microscopy.

In this study, transmission electron microscopy (TEM) and cryo-scanning electron microscopy (cryo-SEM) were evaluated for their ability to detect lipid bodies in microalgae. To do so, Phaeodactylum tricornutum and Nannochloropsis oculata cells were harvested in both the mid-exponential and early stationary growth phase. Two different cryo-SEM cutting methods were compared: cryo-planing and freeze-fracturing. The results showed that, despite the longer preparation time, TEM visualisation preceded by cryo-immobilisation allows a clear detection of lipid bodies and is preferable to cryo-SEM. Using freeze-fracturing, lipid bodies were rarely detected. This was only feasible if crystalline layers in the internal structure, most likely related to sterol esters or di-saturated triacylglycerols, were revealed. Furthermore, lipid bodies could not be detected using cryo-planing. Cryo-SEM is also not the preferred technique to recognise other organelles besides lipid bodies, yet it did reveal chloroplasts in both species and filament-containing organelles in cryo-planed Nannochloropsis oculata samples.