Transmission Electron Microscopy Image Analysis Research Articles

TEM Image Analysis and Simulation Physics for Two-Step Recrystallization of Discretely Amorphized C3H5-Molecular-Ion-Implanted Silicon Substrate Surface

In this study, we investigate the initial rapid recrystallization of a discretely amorphized C3H5-molecular-ion-implanted silicon (Si) substrate surface in the subsequent thermal annealing treatment through the analysis of plan-view transmission electron microscopy (TEM) images and technology computer-aided design (TCAD) process simulation. In the approach of the analysis of the plan-view TEM image of the Si substrate surface, we found that initial rapid recrystallization occurs in the intermediate regions between the residual crystalline and discrete amorphous regions formed in the C3H5-molecular-ion-implanted Si substrate surface. In addition, the TCAD process simulation results indicate that the intermediate regions correspond to the amorphous pockets formed around the discrete amorphous regions in the C3H5-molecular-ion-implanted Si substrate surface and are recrystallized preferentially during the short thermal annealing time. These plan-view TEM image analysis and TCAD process simulation results reveal a two-step recrystallization of the discretely amorphized C3H5-molecular-ion-implaned Si substrate surface. After the initial rapid recrystallization of amorphous pockets in the 1st step, the recrystallization of discrete amorphous regions starts in the 2nd step. The incubation period between the 1st and 2nd steps is the time required to recrystallize the amorphous pockets around the discrete amorphous regions completely and redefine the amorphous/crystalline interface.

Atomic-level characterization of η-twins with non-homogeneous nucleation on the E(Al18Mg3Cr2) phase in 7075 alloy: TEM observations and DFT calculations

In this work, an uncommon type of η-twin with non-homogeneous nucleation on the surface of the E-phase is characterized, and two defects and growth processes of the twin are analyzed. According to the transmission electron microscopy image analysis, heterogeneous nucleation of the η phase at the dominant site of the E phase can lead to the formation of such η-twin only when a rather strict site-direction relationship is satisfied as well as when it is at the interface adjacent to the E phase. The formation of twin defects is related to the E phase but ultimately determined by the nature of the η phase, and the crystallographic relationship between the defect structure and the E phase is self-consistent. Combined with the analytical results from STEM, first-principles calculations show that the solute segregation at the defects reduces the total energy of the system, which favors the transition of the η phase of the heterogeneous nucleation and the formation of twins, and that solute Al is more favorable than Mg. In addition, the elemental distribution and effects in the precipitation-free zone were analyzed by EDS mapping.

Valorization of nanocellulose from bael (Aegle marmelos correa) fruit waste shells: Surface chemistry and morphological analysis

In this work, the waste shells of bael (Aegle marmelos correa) were utilised as a source of cellulose nanocrystals (CNCs). The extracted CNCs were characterized using a series of characterization techniques. The Infrared spectroscopy technique is used for the synthesis process and chemical analysis. The X-ray diffraction peak deconvolution method (area method) shows the crystallinity index (C.I. %) of CNCs is 71 %, while 67 % by Segal's method (intensity method). The average diameter calculated by ImageJ software for AFM (Atomic force microscope) is 47.97 ± 2.50 nm while 23.25 ± 2.50 nm and 44.81 ± 2.50 nm from TEM (Transmission electron microscope) and SEM (Scanning electron microscope) image analysis. The zeta potential count of isolated CNC-BS is −25.72 mV, confirming the CNC-BS suspension's stability. Very good thermal stability (>225 °C) was confirmed by thermal analysis. The high specific surface area of cellulose nanocrystals (205.5 ± 0.20 m2/g) was confirmed by BET analysis.

Synthesis, characterization, and preliminary insights of ZnFe2O4 nanoparticles into potential applications, with a focus on gas sensing

This work presents a hydrothermal-based facile method for synthesizing ZnFe2O4, whose size can be controlled with the concentration of sodium acetate used as a fuel and its physical changes at nanoscales when exposed to two different gases. The structural, morphological, compositional, and electronic properties of the synthesized samples are also presented in this paper. The crystal structure of the synthesized samples was determined using an X-ray Diffractometer (XRD). The results revealed fluctuations in the size, lattice parameter, and strain in the nanoparticles with increasing the concentration of sodium acetate. Field-Emission Scanning Electron Microscopy (FESEM) was used to determine synthesized materials’ morphology and particle size. It revealed that the particles possessed approximately spherical morphology whose size decreased significantly with the increasing amount of sodium acetate. Transmission Electron Microscopy (TEM) was utilized to determine the structure, morphology, and elemental distributions in particles at the nanoscale, and it confirmed the findings of XRD and FESEM analyses. The high-resolution TEM (HRTEM) imaging analysis of the nanoparticles in our studied samples revealed that the particles predominantly possessed (001) type facets. X-ray photoelectron spectroscopy (XPS) and core-loss electron energy loss spectroscopy (EELS) showed an increasing fraction of Fe2+ with the decreasing size of the particles in samples. The Brunauer, Emmett, and Tellers (BET) analysis of samples revealed a higher surface area as the particle size decreases. In addition, the determined surface area and pore size values are compared with the literature, and it was found that the synthesized materials are promising for gas-sensing applications. The ab initio calculations of the Density of States (DOS) and Band structure of (001) surface terminating ZnFe2O4 were carried out using Quantum Espresso software to determine the bandgap of the synthesized samples. They were compared to their corresponding experimentally determined bandgap values and showed close agreement. Finally, in-situ TEM measurement was carried out on one of the four studied samples with robust properties using Ar and CO2 as reference and target gases, respectively. It is concluded from the presented study that the size reduction of the ZnFe2O4 nanoparticles (NPs) tunes the bandgap and provides more active sites due to a higher concentration of oxygen vacancies. The in-situ TEM showed us a nanoscale observation of the change in one of the crystal structure parameters. The d spacing of ZnFe2O4 NPs showed a noticeable fluctuation, reaching more than 5% upon exposure to CO2 and Ar gases.

Automated analysis of grain morphology in TEM images using convolutional neural network with CHAC algorithm

The shape and size of grains significantly impact the properties of polycrystalline materials. In particular, high temperature and radiation exposure in nuclear reactors can lead to considerable grain growth of UO2, thereby substantially modifying the fuel performance. Transmission electron microscopy (TEM) has been used to characterize the grain morphology of polycrystalline materials, but the manual analysis of TEM images is a time-consuming and labor-intensive process, which cannot meet the increasing demand for high-throughput data analytics.This study presents an automated approach we developed for characterizing grain morphology recorded in bright field TEM images during ion irradiations performed in situ. Our approach combines a machine learning model for detecting grain boundaries and a computer vision algorithm named CHAC for selecting well-labeled grains for statistical analysis. Using TEM images acquired from in-situ ion irradiation experiments on nanocrystalline UO2, we demonstrate that this automated approach can achieve comparable results to human experts while significantly reducing the analysis time. Moreover, the machine learning model functions as a "few-shot" model, requiring only a modest number of training images to perform effectively on a specific task. Consequently, researchers in need can efficiently train their own models following the procedures described in this study to automate grain morphology analysis of their own TEM images.

Synthesis and characterization of a novel magnetic chitosan–nickel ferrite nanocomposite for antibacterial and antioxidant properties

A novel nanomagnet modified with nickel ferrite nanoparticles (NPs) coated with hybrid chitosan (Cs–NiFe2O4) was synthesized using the co-precipitation method. The resulting nanomagnets were characterized using various techniques. The size of the nanomagnetic particles was estimated to be about 40 nm based on the transmission electron microscopy (TEM) image and X-ray diffraction analysis (XRD) pattern (using the Debye–Scherrer equation). Scanning electron microscopy (SEM) images indicated that the surface of Cs–NiFe2O4 NPs is flatter and smoother than the uncoated NiFe2O4 NPs. According to value stream mapping (VSM) analysis, the magnetization value of Cs–NiFe2O4 NPs (17.34 emu/g) was significantly lower than NiFe2O4 NPs (40.67 emu/g). The Cs–NiFe2O4 NPs indicated higher antibacterial properties than NiFe2O4 NPs and Cs. The minimum inhibitory concentrations of Cs–NiFe2O4 NPs against S. aureus and E. coli were 128 and 256 mg/mL, respectively. Antioxidant activity (evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging test) for NiFe2O4 NPs and Cs–NiFe2O4 NPs at the concentration of 100 µg/mL were 35% and 42%, respectively. Consequently, the synthesized Cs–NiFe2O4 NPs can be proposed as a viable material for biomedical applications.

Development and In Vitro Evaluation of Crizotinib-Loaded Lipid-Polymer Hybrid Nanoparticles Using Box-Behnken Design in Non-small Cell Lung Cancer.

The goal of the study was to produce, optimize, characterize, and compare crizotinib-loaded lipid-polymer hybrid nanoparticles (CL-LPHNPs), representing a novel contribution to the existing literature, and to determine their anticancer activity in non-small cell lung cancer cells (NSCLC). Box-Behnken design was used to investigate the effect of three independent variables: polymer amount (X1), soy phosphatidylcholine (X2), and DSPE-PEG (X3), on three responses: particle size (Y1), polydispersity index (Y2), and zeta potential (Y3). Different parameters were evaluated on the optimized LPHNP formulations such as encapsulation efficiency, drug release study, transmission electron microscopy (TEM) image analysis, and in vitro cell evaluations. The mean particle size of the optimized formulation is between 120 and 220 nm with a PDI<0.2 and a zeta potential of -10 to -15 mV. The encapsulation efficiency values of crizotinib-loaded PLGA-LPHNPs (CL-PLGA-LPHNPs) and crizotinib-loaded PCL-LPHNPs (CL-PCL-LPHNPs) were 79.25±0.07% and 70.93±1.81%, respectively. Drug release study of CL-PLGA-LPHNPs and CL-PCL-LPHNPs showed a controlled and sustained release pattern as a result of core-shell type. Additionally, after 48 h, CL-PLGA-LPHNPs and CL-PCL-LPHNPs significantly reduced the viability of NCI-H2228 cells compared to free crizotinib. Moreover, CL-PLGA-LPHNPs and CL-PCL-LPHNPs exhibited a significant decrease in RAS, RAF, MEK, and ERK gene/protein expression levels after 48-h incubation. In conclusion, this pioneering study introduces lipid-polymer hybrid nanoparticles containing crizotinib as a novel treatment approach, uniting the advantages of a polymeric core and a lipid shell. The successful formulation optimization using Box-Behnken design yielded nanoparticles with adjustable size, remarkable stability, high drug loading, and a customizable drug release profile. Extensive investigations of key parameters, including particle size, PDI, ZP, TEM analysis, drug release, EE%, and in vitro evaluations, validate the potential of these nanoparticles. Moreover, the examination of two different polymers, PLGA and PCL, highlights their distinct impacts on nanoparticle performance. This research opens up new prospects for advanced therapeutic interventions with lipid-polymer hybrid nanoparticles.

Nanocrystallization of Cu46Zr33.5Hf13.5Al7 Metallic Glass

The recently discovered Cu46Zr33.5Hf13.5Al7 (at.%) bulk metallic glass (BMG) presents the highest glass-forming ability (GFA) among all known copper-based alloys, with a record-breaking critical casting thickness (or diameter) of 28.5 mm. At present, much remains to be explored about this new BMG that holds exceptional promise for engineering applications. Here, we report our study on the crystallization behavior of this new BMG, using isochronal and isothermal differential scanning calorimetry (DSC), X-ray diffraction (XRD), and transmission electron microscopy (TEM). With the calorimetric data, we determine the apparent activation energy of crystallization, the Avrami exponent, and the lower branch of the isothermal time–temperature–transformation (TTT) diagram. With XRD and TEM, we identify primary and secondary crystal phases utilizing samples crystallized to different degrees within the calorimeter. We also estimate the number density, nucleation rate, and growth rate of the primary crystals through TEM image analysis. Our results reveal that the crystallization in this BMG has a high activation energy of ≈360 kJ/mole and that the primary crystallization of this BMG produces a high number density (≈1021 m−3 at 475 °C) of slowly growing (growth rate &lt; 0.5 nm/s at 475 °C) Cu10(Zr,Hf)7 nanocrystals dispersed in the glassy matrix, while the second crystallization event further produces a new phase, Cu(Zr,Hf)2. The results help us to understand the GFA and thermal stability of this new BMG and provide important guidance for its future engineering applications, including its usage as a precursor to glass–crystal composite or bulk nanocrystalline structures.

Herpes Simplex Virus Infection Alters the Immunological Properties of Adipose-Tissue-Derived Mesenchymal-Stem Cells.

The proper functioning of mesenchymal stem cells (MSCs) is of paramount importance for the homeostasis of the body. Inflammation and infection can alter the function of MSCs, which can also affect the regenerative potential and immunological status of tissues. It is not known whether human herpes simplex viruses 1 and 2 (HSV1 and HSV2), well-known human pathogens that can cause lifelong infections, can induce changes in MSCs. In non-healing ulcers, HSV infection is known to affect deeper tissue layers. In addition, HSV infection can recur after initially successful cell therapies. Our aim was to study the response of adipose-derived MSCs (ADMSCs) to HSV infection in vitro. After confirming the phenotype and differentiation capacity of the isolated cells, we infected the cells in vitro with HSV1-KOS, HSV1-532 and HSV2 virus strains. Twenty-four hours after infection, we examined the gene expression of the cells via RNA-seq and RT-PCR; detected secreted cytokines via protein array; and determined autophagy via Western blot, transmission electron microscopy (TEM) and fluorescence microscopy. Infection with different HSV strains resulted in different gene-expression patterns. In addition to the activation of pathways characteristic of viral infections, distinct non-immunological pathways (autophagy, tissue regeneration and differentiation) were also activated according to analyses with QIAGEN Ingenuity Pathway Analysis, Kyoto Encyclopedia of Genes and Genome and Genome Ontology Enrichment. Viral infections increased autophagy, as confirmed via TEM image analysis, and also increased levels of the microtubule-associated protein light chain 3 (LC3B) II protein. We identified significantly altered accumulation for 16 cytokines involved in tissue regeneration and inflammation. Our studies demonstrated that HSV infection can alter the viability and immunological status of ADMSCs, which may have implications for ADMSC-based cell therapies. Alterations in autophagy can affect numerous processes in MSCs, including the inhibition of tissue regeneration as well as pathological differentiation.

Deep Learning-Based TEM Image Analysis for Fully Automated Detection of Gold Nanoparticles Internalized Within Tumor Cell.

Transmission electron microscopy (TEM) imaging can be used for detection/localization of gold nanoparticles (GNPs) within tumor cells. However, quantitative analysis of GNP-containing cellular TEM images typically relies on conventional/thresholding-based methods, which are manual, time-consuming, and prone to human errors. In this study, therefore, deep learning (DL)-based methods were developed for fully automated detection of GNPs from cellular TEM images. Several models of "you only look once (YOLO)" v5 were implemented, with a few adjustments to enhance the model's performance by applying the transfer learning approach, adjusting the size of the input image, and choosing the best optimization algorithm. Seventy-eight original (12,040 augmented) TEM images of GNP-laden tumor cells were used for model implementation and validation. A maximum F1 score (harmonic mean of the precision and recall) of 0.982 was achieved by the best-trained models, while mean average precision was 0.989 and 0.843 at 0.50 and 0.50-0.95 intersection over union threshold, respectively. These results suggested the developed DL-based approach was capable of precisely estimating the number/position of internalized GNPs from cellular TEM images. A novel DL-based TEM image analysis tool from this study will benefit research/development efforts on GNP-based cancer therapeutics, for example, by enabling the modeling of GNP-laden tumor cells using nanometer-resolution TEM images.

Atomic-Scale Polarization and Strain at the Surface of Lead Halide Perovskite Nanocrystals.

Inorganic halide perovskite nanocrystals (NCs) are being widely explored as next-generation optoelectronic materials. Critical to understanding the optoelectronic properties and stability behavior of perovskite NCs is the material's surface structure, where the local atomic configuration deviates from that of the bulk. Through low-dose aberration-corrected scanning transmission electron microscopy and quantitative imaging analysis techniques, we directly observed the atomic structure at the surface of the CsPbBr3 NCs. CsPbBr3 NCs are terminated by a Cs-Br plane, and the surface Cs-Cs bond length decreases significantly (∼5.6%) relative to the bulk, imposing compressive strain and inducing polarization, which we also observed in CsPbI3 NCs. Density functional theory calculations suggest such a reconstructed surface contributes to the separation of holes and electrons. These findings enhance our fundamental understanding of the atomic-scale structure, strain, and polarity at the surface of inorganic halide perovskites and provide valuable insights into designing stable and efficient optoelectronic devices.

Kinetic Modulation of Amyloid‐β (1‐42) Fibrillation and Alleviated Cytotoxicity with Rationally Designed Point Mutants

AbstractBackgroundMost Alzheimer’s disease (AD) treatments focus on symptomatic relief by boosting the availability of neurotransmitters in the brain. Aside from symptomatic therapies, the amyloid‐β (Aβ) targeting approach has recently been established to reduce or postpone the production of Aβ plaques.1 Therefore, understanding the pathogenesis of AD requires regulation of Aβ fibrillation.MethodWe used the CamSol method and molecular dynamics simulations to find a group of residues that were significantly associated with Aβ fibrillation. To investigate the suppressed amyloid aggregation and reduced cytotoxicity of the designed mutants, we performed multiple in vitro experiments such as thioflavin T assay, circular dichroism spectroscopy measurement, transmission electron microscopy image analysis, liquid chromatography‐mass spectrometry based quantification, and cell viability test. We also characterized structural dynamics of the designed mutants using a multidisciplinary biophysical approach with small‐angle X‐ray scattering, ion mobility‐mass spectrometry, additional in silico experiments, and mass spectrometry.ResultWe rationally designed mutant constructs to suppress the fibrillation process using comprehensive molecular dynamics simulations and the atomic resolution structure of fibrils. Then, we used a multidisciplinary biophysical technique to investigate the physicochemical characteristics and unveil the structural basis associated with reduced self‐assembly. Lastly, cell‐based tests were performed to evaluate the alleviated cytotoxicity of designed mutant candidates.ConclusionMore generally, our method for modulating the self‐assembly property of the pathologically disordered proteins offers a novel viewpoint to treating neurodegenerative diseases and other protein folding‐related issues.Reference:1. Sevigny, J., et al. “The antibody aducanumab reduces A beta plaques in Alzheimer’s disease.” Nature 2016, 537(7618), 50‐56.

Relationship of Internal Stress Fields with Self-Organization Processes in Hadfield Steel under Tensile Load

The effect of tensile strains on the microstructure of Hadfield steel was studied by transmission electron microscopy (TEM). Stages of the obtained stress–strain curves were observed, and correlated well with the evolution of the dislocation substructure. Based on an analysis of TEM images, quantitative parameters were determined, such as the material volume fractions, in which slip and twinning occurred, as well as twinning, which developed in one, two and three systems. Some transformation mechanisms were reported that caused great hardening of Hadfield steel. In particular, a complex defect substructure formed in a self-organized manner due to the formation of cells, the dislocations retarded by their walls, as well as the deceleration of dislocations on twins and, vice versa, of twins on dislocations. These factors affected both the average and excess local density of dislocations. Additionally, they resulted in elastic stress fields, which manifested themselves in the curvature–torsion gradient of the crystal lattice. A high level of stresses caused by solid-solution strengthening prevented the relaxation of elastic ones, contributing to the strain hardening of the Hadfield steel.

Preparation and characterization of cellulose nanocrystals from paper mulberry fibers

The applicability of paper mulberry fiber (PM-FB), which is bast fiber, for manufacturing cellulose nanocrystals (CNCs) with high-yield was investigated. The PM-FB and hardwood bleached kraft pulp (Hw-BKP) were hydrolyzed under different sulfuric acid concentrations, reaction times, and reaction temperatures. The dependence of the CNC yield on the hydrolysis conditions and crystallinity of the raw materials was analyzed. The functional groups of the CNCs and their zeta potentials were determined. The fiber length and width of the individual CNCs were determined by transmission electron microscopy image analysis. The PM-FB showed a higher crystallinity of 86.8% compared to that of Hw-BKP and exhibited a high CNC yield of 55% under strong hydrolysis conditions. The sulfate group was introduced into the CNCs, which increased their negative charge. The fiber width of PM-FB-based CNCs (PM-CNCs) was larger than that of Hw-BKP-based CNCs (Hw-CNCs), and the aspect ratio ranged from 29.0 to 12.2 depending on the hydrolysis conditions. The yield of PM-CNCs was higher than that of Hw-CNCs under the same hydrolysis conditions. In addition, both CNCs exhibited similar quality. Therefore, PM-FB is a promising raw material for efficient CNC manufacturing.

An investigation on the structural and optical properties of mercaptosuccinic acid capped cadmium telluride quantum dots

In this work, a sonication induced modified wet chemical approach is adopted to synthesize highly luminescent and water soluble cadmium telluride (CdTe) quantum dots (QDs). The morphology, size, crystal structural, and optical properties of CdTe QDs are investigated for different refluxing time (1–4 h). The refluxing time-dependent optical constants viz. band gap energy and Urbach energy of the QDs are estimated from UV–Visible absorption spectra. The optical band gap energy decreased from ~ 2.12 to 1.92 eV and the Urbach energy increased from ~ 361 to 487 meV, with the increase in refluxing time. CdTe QDs are found to be uniform in size. The average size of the QDs estimated from the High Resolution Transmission Electron Microscope image analysis is about 5.8 and 8.2 nm for refluxing times 1 and 4 h, respectively. The growth mechanism of the QDs as a function of refluxing time has also been discussed. The fluorescence spectra of the QDs, revealed emission peaks having wavelength from ~ 534 to 585 nm, under the excitation wavelength of 320 nm. The fluorescence emission peaks showed a bathochromic shift with increasing refluxing time. CdTe QDs also exhibit excitation-dependent fluorescence behaviour. Two crystalline phases of the CdTe QDs, namely hexagonal and cubic are confirmed from the High Resolution Transmission Electron Microscope images and Selected Area Electron Diffraction patterns analysis. The phase transformation from hexagonal to cubic is successfully achieved by tuning the refluxing time from 1 to 4 h.

Hexahedron Symmetry and Multidirectional Facet Coupling of Orthorhombic CsPbBr3 Nanocrystals

The cube shape of orthorhombic phase CsPbBr3 nanocrystals possesses the ability of selective facet packing that leads to 1D, 2D, and 3D nanostructures. In solution, their transformation with linear one-dimensional packing to nanorods/nanowires is extensively studied. Here, multifacet coupling in two directions of the truncated cube nanocrystals to rod couples and then to single-crystalline rectangular rods is reported. With extensive high-resolution transmission electron microscopy image analysis, length and width directions of these nanorods are derived. For the seed cube structures, finding {110} and {002} facets has remained difficult as these possess the hexahedron symmetry and their size remains smaller; however, for nanorods, these planes and the ⟨110⟩ and ⟨001⟩ directions are clearly identified. From nanocrystal to nanorod formation, the alignment directions are observed as random (as shown in the abstract graphic), and this could vary from one to the other rods obtained in the same batch of samples. Moreover, seed nanocrystal connections are derived here as not random and are rather induced by addition of the calculated amount of additional Pb(II). The same has also been extended to nanocubes obtained from different literature methods. It is predicted that a Pb-bromide buffer octahedra layer was created to connect two cubes, and this can connect along one, two, or even more facets of cubes simultaneously to connect other cubes and form different nanostructures. Hence, these results here provide some basic fundamentals of seed cube connections, the driving force to connect those, trapping the intermediate to visualize their alignments for attachments, and identifying and establishing the orthorhombic ⟨110⟩ and ⟨001⟩ directions of the length and width of CsPbBr3 nanostructures.

Experimental evaluation of dimensionless extinction coefficient of soot in co-flow laminar diffusion flames at elevated pressures

Dimensionless extinction coefficient (Ke) is one of the most important optical parameters of soot since it affects the accuracy of laser extinction measurement of soot volume fraction. In literature, Ke values have been measured for soot from laminar and turbulent flames with different fuels at atmospheric pressure. However, relevant studies about the measurement of Ke values in flames at elevated pressures are still lacking. In this study, a simultaneous gravity sampling and laser extinction system (GSLE) capable of operating in a combustion chamber was proposed to evaluate the value of Ke in laminar diffusion flames at elevated pressures. Methane and two straight-chain alkanes (n-heptane and n-dodecane) were selected as fuels for comparative studies at 0.1–0.8 MPa and 0.1–0.5 MPa, respectively. The morphology properties of soot samples were analyzed quantitatively by transmission electron microscopy (TEM). The results show the Ke values of in-flame soot for methane, n-heptane, and n-dodecane range from 6.1 to 9.7, 6.5 to 10.7, and 7.4 to 10.9 at the corresponding experimental pressures, respectively. The Ke values of in-flame soot for all three fuels increase with pressure. The above results conclude that using a constant Ke value measured at atmospheric pressure may result in larger errors in the measurement of soot volume fraction in flames at elevated pressure. The quantitative analysis of TEM images shows that the significant variation of soot morphology parameters with pressure is one of the main factors for the variation of Ke value with pressure.

Meroterpenoids from Gongolaria abies-marina against Kinetoplastids: In Vitro Activity and Programmed Cell Death Study.

Leishmaniasis and Chagas disease affect millions of people worldwide. The available treatments against these parasitic diseases are limited and display multiple undesired effects. The brown alga belonging to the genus Gongolaria has been previously reported as a source of compounds with different biological activities. In a recent study from our group, Gongolaria abies-marine was proven to present antiamebic activity. Hence, this brown alga could be a promising source of interesting molecules for the development of new antiprotozoal drugs. In this study, four meroterpenoids were isolated and purified from a dichloromethane/ethyl acetate crude extract through a bioguided fractionation process targeting kinetoplastids. Moreover, the in vitro activity and toxicity were evaluated, and the induction of programmed cell death was checked in the most active and less toxic compounds, namely gongolarone B (2), 6Z-1'-methoxyamentadione (3) and 1'-methoxyamentadione (4). These meroterpenoids triggered mitochondrial malfunction, oxidative stress, chromatin condensation and alterations of the tubulin network. Furthermore, a transmission electron microscopy (TEM) image analysis showed that meroterpenoids (2-4) induced the formation of autophagy vacuoles and ER and Golgi complex disorganization. The obtained results demonstrated that the mechanisms of action at the cellular level of these compounds were able to induce autophagy as well as an apoptosis-like process in the treated parasites.

Genetic mapping and molecular mechanism behind color variation in the Asian vine snake

BackgroundReptiles exhibit a wide variety of skin colors, which serve essential roles in survival and reproduction. However, the molecular basis of these conspicuous colors remains unresolved.ResultsWe investigate color morph-enriched Asian vine snakes (Ahaetulla prasina), to explore the mechanism underpinning color variations. Transmission electron microscopy imaging and metabolomics analysis indicates that chromatophore morphology (mainly iridophores) is the main basis for differences in skin color. Additionally, we assemble a 1.77-Gb high-quality chromosome-anchored genome of the snake. Genome-wide association study and RNA sequencing reveal a conservative amino acid substitution (p.P20S) in SMARCE1, which may be involved in the regulation of chromatophore development initiated from neural crest cells. SMARCE1 knockdown in zebrafish and immunofluorescence verify the interactions among SMARCE1, iridophores, and tfec, which may determine color variations in the Asian vine snake.ConclusionsThis study reveals the genetic associations of color variation in Asian vine snakes, providing insights and important resources for a deeper understanding of the molecular and genetic mechanisms related to reptilian coloration.

Visualising microstructural dynamics of titanium aluminium nitride coatings under variable-temperature oxidation

Understanding the link between titanium-aluminium nitride’s (Ti1-xAlxN) physicochemical properties and structural dynamics during operation is essential to designing and fabricating advanced ceramic coatings. Here, we directly visualise the oxidation of Ti1-xAlxN (for x = 0, 0.18, 0.44, & 0.67) coatings from 100 to 1000 °C using environmental transmission electron microscopy (ETEM) imaging and energy dispersive X-ray spectroscopy (EDX) analysis. The high-frame-rate ETEM movies show that oxidation in TiN proceeds at the grain boundaries and cracks; in contrast, Ti1-xAlxN coatings transform from large as-deposited grains into oxide nanoparticles. Moreover, high-resolution ETEM imaging show the presence of anatase TiO2 at the early stages of oxidation across all compositions. Above ∼ 850 °C, the oxide nanoparticles grow through crystal merging, diffusion and recrystallisation to form rutile TiO2. The EDX elemental maps coupled with secondary electron imaging reveal a uniform TiO2 sublayer decorated with increasing coverage of Al2O3 particles for x = 0.18 to 0.44. In contrast, coatings with x = 0.67 reveal a complete in-plane phase separation of Al- and Ti-oxides, which can rationalise their decreasing long-term oxidation resistance. Finally, the study provides unique insight into the real-time structural dynamics underpinning the oxidation resistance of Ti1-xAlxN coatings.