Transmission Electron Tomography Research Articles

Design and evaluation of a multi-epitope HIV-1 vaccine based on human parvovirus virus-like particles.

The development of a protective HIV vaccine remains a challenge given the high antigenic diversity and mutational rate of the virus, which leads to viral escape and establishment of reservoirs in the host. Modern antigen design can guide immune responses towards conserved sites, consensus sequences or normally subdominant epitopes, thus enabling the development of broadly neutralizing antibodies and polyfunctional lymphocyte responses. Conventional epitope vaccines can often be impaired by low immunogenicity, a limitation that may be overcome by using a carrier system. In this work, Virus-Like Particles (VLPs) of the B19 human parvovirus were used as a carrier system for multiple HIV-1 epitopes displayed on the surface. Epitopes were selected based on being the binding site of broadly neutralizing antibodies (bnAbs) in patients. Full capsid assembly was confirmed by dynamic light scattering and morphology was confirmed by transmission electron imaging. The resulting chimeric VLPs were termed "VLP-MHIV-A". Antigenicity was confirmed by HIV+ patient sera binding to the chimeric VLP-MHIV-A. To evaluate immunogenicity, female C57bl/6 mice were immunized with the chimeric VLPs either via the intramuscular or subcutaneous route, specific humoral and cellular responses were evaluated, and neutralizing activity was measured in an in vitro reporter cell system. Substantial antibodies against whole-VLPs were induced in serum and vaginal lavages for both immunization routes. Antibody responses against the CD4 binding site, V3 loop and several epitopes of gp41 were detected. Both immunization routes demonstrated neutralizing activity; however, the I.M. route was more effective, showing significant neutralizing activity with up to 50% inhibition of a tier 1 clade B virus infection. Taken as a whole, these results show that chimeric VLPs are an effective antigen capable of inducing HIV-1 specific antibodies with neutralizing activity.

Scanning transmission electron tomography to study virus assembly: Review for the retirement of Paul Walther.

In this short and popular review, we summarise some of our findings analysing the replication cycles of large DNA viruses using scanning transmission electron tomography (STEM tomography) that we applied in the laboratory of Paul Walther. It is also a tribute to a very kind and expert scientist, who recently retired. Transmission electron microscopy (TEM), in particular cryo-EM, has benefited tremendously from recent developments in instrumentation. However, TEM imaging remains limited by the thickness of the specimen and classical thin-section TEM typically generates 2D representations of 3D volumes. Although TEM tomography can partly overcome this limitation, the thickness of the sample, the volume that can be analysed in 3D, remains limiting. STEM tomography can partly overcome this problem, as it allows for the analysis of thicker samples, up to 1 µm in thickness. As such, it is an interesting imaging technique to analyse large DNA viruses, some of which measure 1 µm or more, and which is the focus of our research interest.

Pt/Ni-Fe Oxide-Based Catalyst for Hydrogen Evolution Reaction in Alkaline Media

The hydrogen evolution reaction (HER) as part of water splitting is a fundamental electrocatalytic process and plays a crucial role in hydrogen-based energy conversion. Although platinum and its group metals rank among the most active electrocatalysts for the HER, the slow reaction kinetics under alkaline media conditions has hindered their application in alkaline water electrolyzers. Therefore, much effort has been devoted to exploring highly active electrocatalysts for the alkaline HER. Transition-metal hydroxides/oxides are efficient for the prior water-dissociation step of alkaline HER, and therefore, combining these materials with Pt may be promising candidates for alkaline HER catalysts. Here, we demonstrate that Pt nanoparticles supported on interconnected NiFe oxide particles can serve as enhanced catalysts for alkaline HER.The NiFe oxide was synthesized by the flame pyrolysis method.1,2 The Pt nanoparticles were loaded on the NiFe oxide by a modified colloidal method.3,4 The as-prepared Pt/NiFe oxide sample was reduced in 5% H2 (N2 balance) at 100 oC for 1h. The Pt loading was determined to be 28.3 wt% by inductively coupled plasma-optical emission spectroscopy (ICP-OES). The scanning transmission electron microscopy (STEM) image was shown in Figure 1 ((a) secondary electron (SE) image and (b) transmission electron (TE) image). It can be seen that Pt nanoparticles (some interconnected to form rod/wire-like structures) are dispersed on the NiFe oxide support. Figure 1c shows the HER polarization curves of Pt/NiFe oxide compared with a commercial catalyst Pt/C (TEC10E50E, TKK). The HER specific activity (j s) and mass activity (MA) were summarized in Figure 1d. The HER activity is shown to be greatly enhanced on the Pt/NiFe oxide catalyst, with the specific activity and mass activity (@-0.1 V) being approximately 3.9 and 2.4 times higher than that of Pt/C, respectively. The high mass activity of Pt/NiFe oxide would make it possible to lower the Pt usage, and thus cost, when implemented as a cathode in a practical alkaline water electrolyzer. In addition, the Pt/NiFe oxide catalyst was further heat-treated at high temperatures to obtain different nanostructures and elucidate the structure-activity relationship, achieving optimal HER activity at a moderate hydrogen binding energy. These results are expected to aid in the design of highly efficient HER catalysts for hydrogen production by alkaline water electrolysis. Acknowledgement This work was partially supported by the JSPS KAKENHI (23H02059) and the projects from the New Energy and Industrial Technology Development Organization (NEDO) of Japan. References K. Kakinuma, M. Uchida, T. Kamino, H. Uchida, and M. Watanabe, Electrochim. Acta, 56, 2881 (2011).G. Shi, T. Tano, D. A. Tryk, M. Yamaguchi, A. Iiyama, M. Uchida, K. Iida, C. Arata, S. Watanabe, and K. Kakinuma, ACS Catal., 12, 14209 (2022).G. Shi, T. Tano, D. A. Tryk, A. Iiyama, M. Uchida, and K. Kakinuma, ACS Catal., 11, 5222 (2021).G. Shi, T. Tano, D. A. Tryk, T. Uchiyama, A. Iiyama, M. Uchida, K. Terao, M. Yamaguchi, K. Tamoto, Y. Uchimoto, and K. Kakinuma, ACS Catal., 13, 12299 (2023). Figure 1

Oogenesis and Spermatogenesis of the Triploid Black Tiger Shrimp, Penaeus monodon

Triploidy (3n) induction of Penaeus monodon was performed separately by Australian and Thai groups of researchers 14 years ago, incidentally at the same period. The Australian group employed the chemical induction method, while the Thai group the cold shock one, and both groups obtained 3n P. monodon in their attempts. The success has led to several studies on the physiology of the 3n P. monodon, including growth, survival and reproductive functions. Both groups reported sterility of the 3n shrimp. The Australian group reported defected oogenesis and spermatogenesis of the 3n shrimp examined at subadult stage. Since the evaluation of the reproductive functions should be performed at the adult stage of the animals, we, therefore, performed in-depth studies on oogenesis and spermatogenesis of adult 3n P. monodon induced by cold shock. The studies include gross observation of the ovary, light (LM) and transmission electron (TEM) microscopy and image analysis of sex cells. The ovary of the 3n P. monodon females could not develop to full-maturation and their gonadosomatic index (GSI) was significantly lower than that of the 2n shrimp. Oogenesis of the 3n females proceeded from oogonia to cortical rod oocytes, but with significantly lower percentage than that of the 2n shrimp. The GSI of the 3n males was significantly lower than that of the 2n shrimp. Their spermatogenesis, however, proceeded normally from spermatogonia to spermatozoa, but with low density of spermatozoa in the seminiferous tubule and vas deferens, and none in the terminal ampoule. The average nuclear area of the 3n spermatozoa was significantly lower than that of the 2n shrimp as well. Altogether, these results suggest that 3n P. monodon induced by cold shock had defect in both oogenesis and spermatogenesis, probably more in quantity than in quality. HIGHLIGHTS Oogenesis and spermatogenesis of the triploid black tiger shrimp, monodon, induced by cold shock were studied. The study found abnormalities in the spermatogenesis, but not oogenesis, of the triploid P. monodon induced by cold shock. It may be concluded that triploidy condition of P. monodon induced by cold shock affects meiotic, but not mitotic activity of the sex cells. GRAPHICAL ABSTRACT

A Three–Dimensional Nanoscale View of Electrocatalyst Degradation in Hydrogen Fuel Cells

AbstractThe loss of platinum (Pt) electrochemically active surface area (ECSA) is a critical degradation mode that often becomes a limiting factor for heavy‐duty proton exchange membrane fuel cell vehicles. High surface area carbon supports have been shown to improve Pt dispersion and limit detrimental ionomer‐electrocatalyst interactions due to their large interior pore volume. In this work, using automated scanning transmission electron tomography, the degradation of nanoparticles located on the interior versus exterior surfaces of the carbon support is compared following a catalyst‐specific accelerated stress test (AST) of 90,000 voltage cycles between 0.6 V to 0.95 V. The results reveal a notable increase in median particle size for both interior and exterior Pt catalyst particles, with a slightly higher increase in particle size distribution and loss of specific surface area for the particles located on the exterior carbon surface. The fraction of Pt nanoparticles that reside within the interior of the carbon support also increased following the AST test, accompanied by evidence of an increase in average carbon mesopore size. The results shed light on the degradation mechanisms affecting electrochemical properties and the enhanced particle accessibility at lower relative humidity.

Selective colorimetric sensing of histidine in aqueous media via Ag nanotriangles in the presence of HgCl2

Silver nanotriangles (AgNTs) were successfully synthesized as a colorimetric probe for selective and sensitive histidine detection in aqueous media within a 15–100 µM range and a detection limit of 330 nM using UV–Vis spectroscopy. The interaction of HgCl2 with AgNTs would lead to the formation of disk-shaped Ag/Hg amalgam as observed from the transmission electron images and X-ray diffraction patterns. Histidine prevents these structural and morphological changes and accordingly, the detection approach was developed based on the correlation between the histidine concentration and the in-plane dipole plasmon resonance (DPR) intensity.

Controllable Fabrication of Gallium Ion Beam on Quartz Nanogrooves.

Nanogrooves with high aspect ratios possess small size effects and high-precision optical control capabilities, as well as high specific surface area and catalytic performance, demonstrating significant application value in the fields of optics, semiconductor processes, and biosensing. However, existing manufacturing methods face issues such as complexity, high costs, low efficiency, and low precision, especially in the difficulty of fabricating nanogrooves with high resolution on the nanoscale. This study proposes a method based on focused ion beam technology and a layer-by-layer etching process, successfully preparing V-shaped and rectangular nanogrooves on a silicon dioxide substrate. Combining with cellular automaton algorithm, the ion sputtering flux and redeposition model was simulated. By converting three-dimensional grooves to discrete rectangular slices through a continuous etching process and utilizing the sputtering and redeposition effects of gallium ion beams, high-aspect-ratio V-shaped grooves with up to 9.6:1 and rectangular grooves with nearly vertical sidewalls were achieved. In addition, the morphology and composition of the V-shaped groove sidewall were analyzed in detail using transmission electron microscopy (TEM) and tomography techniques. The influence of the etching process parameters (ion current, dwell time, scan times, and pixel overlap ratio) on groove size was analyzed, and the optimized process parameters were obtained.

Morphology and crystallography of E-(Al18Cr2Mg3) nano dispersoids in 7475 Al alloy

The morphology and crystallography of E-(Al18Cr2Mg3) nano dispersoids in 7475 Al alloy have been studied by using transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and electron tomography (ET). Seven distinct morphologies have been three-dimensionally distinguished at the nanoscale: (i) triangular plates on {111}Al, (ii) hexagonal plates on {111}Al, (iii) rods parallel to <110>Al, (iv) small tetrahedra with {111}Al facets, (v) small octahedra, (vi) spheres and (vii) irregular shapes. Twinning can contribute to the diverse morphologies of E nano dispersoids. The orientation relationships (ORs) between E nano dispersoids and Al matrix have been systematically investigated by selected area electron diffraction (SAED) patterns, HRTEM and matrix calculation. The results from the matrix calculation indicate the absence of clear ORs between E nano dispersoids and Al matrix in 7475 Al alloy.

Transmission Electron Imaging and Diffraction of Asbestos Fibers in an SEM

Transmission Electron Imaging and Diffraction of Asbestos Fibers in an SEM

Characterization and the physical properties of nano-sized Bi2O3/polymer for energy and high-refractive index applications

The present work focuses on developing nanocomposites for optoelectronics and energy storage devices leveraging the unique physicochemical features of bismuth (III) oxide (Bi2O3) using a polyvinyl pyrrolidone/polyvinyl alcohol matrix (PV(A/P)). Bi2O3 nanofillers (NF) and Bi2O3/PV(A/P) nanocomposite (NC) films were prepared by facile chemical solution approaches. The X-ray (XRD) data and a transmission electron image revealed that the NF exhibits a monoclinic phase, resembling slightly deformed agglomerated spheres. In the FTIR spectrum, different stretching vibrations of Bi-O-Bi bonds were found, along with their complexation and interaction with the reactive groups in the matrix. The SEM revealed a uniform distribution of Bi2O3 NF loading up to 1.5 wt% on the sample’s surface. Thermal analyses (TGA and DSC thermograms) were used to study the thermal stability, melting, and decomposition temperatures of the NC films. The dielectric features were studied under frequencies between 2 × 103 and 8 × 106 Hz and heating from 293 to 393 K. The dielectric constant and energy density were increased with Bi2O3 NF content. This implies that we can utilize the prepared NC for the fabrication of energy storage devices. The influences of the Bi2O3 NF doping level on the transmittance, band gap, Urbach energy, refractive index, conductivity, and other physical parameters were discussed. The modifications induced in the dielectric/optical parameters make the prepared NC films the best candidates for applications requiring a high refractive index, such as optical coatings and integrated photonic devices.

Extracellular sombrero vesicles are hallmarks of eosinophilic cytolytic degranulation in tissue sites of human diseases.

Eosinophil sombrero vesicles are large tubular carriers resident in the cytoplasm of human eosinophils, identifiable by transmission electron microscopy, and important for immune mediator transport. Increased formation of sombrero vesicles occurs in activated eosinophils in vitro and in vivo. In tissue sites of eosinophilic cytolytic inflammation, extracellular eosinophil sombrero vesicles are noted, but their frequency and significance in eosinophil-associated diseases remain unclear. Here, we performed comprehensive quantitative transmission electron microscopy analyses and electron tomography to investigate the numbers, density, integrity, and 3-dimensional structure of eosinophil sombrero vesicles in different biopsy tissues from 5 prototypic eosinophil-associated diseases (eosinophilic chronic rhinosinusitis/nasal sinuses, ulcerative colitis/intestines, hypereosinophilic syndrome/skin, dermatitis/skin, and schistosomiasis/rectum). The morphology of extracellular eosinophil sombrero vesicles was also compared with that of cytoplasmic eosinophil sombrero vesicles, isolated by subcellular fractionation from peripheral blood eosinophils. We demonstrated that (i) eosinophil cytolysis, releasing intact sombrero vesicles and membrane-bound granules, is a consistent event in all eosinophil-associated diseases; (ii) eosinophil sombrero vesicles persist intact even after complete disintegration of all cell organelles, except granules (late cytolysis); (iii) the eosinophil sombrero vesicle population, composed of elongated, curved, and typical sombreros, and the eosinophil sombrero vesicle 3-dimensional architecture, diameter, and density remain unchanged in the extracellular matrix; (iv) free eosinophil sombrero vesicles closely associate with extracellular granules; and (v) free eosinophil sombrero vesicles also associate with externalized chromatin during eosinophil ETosis. Remarkably, eosinophil sombrero vesicles appeared on the surface of other cells, such as plasma cells. Thus, eosinophil cytolysis/ETosis can secrete intact sombrero vesicles, alongside granules, in inflamed tissues of eosinophil-associated diseases, potentially serving as propagators of eosinophil immune responses after cell death.

Automated segmentation of cell organelles in volume electron microscopy using deep learning.

Recent advances in computing power triggered the use of artificial intelligence in image analysis in life sciences. To train these algorithms, a large enough set of certified labeled data is required. The trained neural network is then capable of producing accurate instance segmentation results that will then need to be re-assembled into the original dataset: the entire process requires substantial expertise and time to achieve quantifiable results. To speed-up the process, from cell organelle detection to quantification across electron microscopy modalities, we propose a deep-learning based approach for fast automatic outline segmentation (FAMOUS), that involves organelle detection combined with image morphology, and 3D meshing to automatically segment, visualize and quantify cell organelles within volume electron microscopy datasets. From start to finish, FAMOUS provides full segmentation results within a week on previously unseen datasets. FAMOUS was showcased on a HeLa cell dataset acquired using a focused ion beam scanning electron microscope, and on yeast cells acquired by transmission electron tomography. RESEARCH HIGHLIGHTS: Introducing a rapid, multimodal machine-learning workflow for the automatic segmentation of 3D cell organelles. Successfully applied to a variety of volume electron microscopy datasets and cell lines. Outperforming manual segmentation methods in time and accuracy. Enabling high-throughput quantitative cell biology.

Wound Dressing Based on Silver Nanoparticle Embedded Wool Keratin Electrospun Nanofibers Deposited on Cotton Fabric: Preparation, Characterization, Antimicrobial Activity, and Cytocompatibility.

Wool keratin (WK) protein is attractive for wound dressing and biomedical applications due to its excellent biodegradability, cytocompatibility, and wound-healing properties. In this work, WK-based wound dressings were prepared by depositing WK/poly(vinyl alcohol) (PVA) and silver nanoparticle (Ag NP)-embedded WK/PVA composite nanofibrous membranes on cotton fabrics by electrospinning. Ag NPs were biosynthesized by reduction and stabilization with sodium alginate. The formed Ag NPs were characterized by ultraviolet-visible and Fourier transform infrared (FTIR) spectroscopy, and their size was determined by transmission electron microscopy and image analysis. The formed Ag NPs were spherical and had an average diameter of 9.95 nm. The produced Ag NP-embedded WK/PVA composite nanofiber-deposited cotton fabric surface was characterized by FTIR and dynamic contact angle measurements, and the nanofiber morphologies were characterized by scanning electron microscopy. The average diameter of the nanofibers formed by 0.1% Ag NP-embedded WK/PVA solution was 146.7 nm. The antibacterial activity of the surface of cotton fabrics coated with electrospun composite nanofibers was evaluated against the two most common wound-causing pathogens, Staphylococcus aureus and Pseudomonas aeruginosa. The cotton fabric coated with 0.1% Ag NP-embedded WK/PVA nanofibers showed very good antibacterial activity against both pathogens, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay results showed good cytocompatibility against L-929 mouse fibroblast cells. However, the increase in Ag NP content in the nanofibers to 0.2% negatively affected the cell viability due to the high release rate of Ag ions. The results achieved show that the developed wound dressing has good potential for wound healing applications.

Tooth acellular extrinsic fibre cementum incremental lines in humans are formed by parallel branched Sharpey’s fibres and not by its mineral phase

In humans, the growth pattern of the acellular extrinsic fibre cementum (AEFC) has been useful to estimate the age-at-death. However, the structural organization behind such a pattern remains poorly understood. In this study tooth cementum from seven individuals from a Mexican modern skeletal series were analyzed with the aim of unveiling the AEFC collagenous and mineral structure using multimodal imaging approaches. The organization of collagen fibres was first determined using: light microscopy, transmission electron microscopy (TEM), electron tomography, and plasma FIB scanning electron microscopy (PFIB-SEM) tomography. The mineral properties were then investigated using: synchrotron small-angle X-ray scattering (SAXS) for T-parameter (correlation length between mineral particles); synchrotron X-ray diffraction (XRD) for L-parameter (mineral crystalline domain size estimation), alignment parameter (crystals preferred orientation) and lattice parameters a and c; as well as synchrotron X-ray fluorescence for spatial distribution of calcium, phosphorus and zinc. Results show that Sharpey’s fibres branched out fibres that cover and uncover other collagen bundles forming aligned arched structures that are joined by these same fibres but in a parallel fashion. The parallel fibres are not set as a continuum on the same plane and when they are superimposed project the AEFC incremental lines due to the collagen birefringence. The orientation of the apatite crystallites is subject to the arrangement of the collagen fibres, and the obtained parameter values along with the elemental distribution maps, revealed this mineral tissue as relatively homogeneous. Therefore, no intrinsic characteristics of the mineral phase could be associated with the alternating AEFC incremental pattern.

Strain-modulated Mn-rich layered oxide enables highly stable potassium-ion batteries

Mn-rich layered oxides show great promise as cathode materials for potassium-ion batteries due to their high capacity and cost-effectiveness. However, internal structural strain and irreversible phase transitions caused by Jahn-Teller distortion affect their cycling stability. Here, we present an efficient strategy to concurrently modulate the internal strain and suppress the irreversible phase transition in Mn-rich cathodes by incorporating amounts of zinc (Zn) ions into the transition metal layers. The substituted Zn serves to regulate local chemistry, thereby mitigating octahedral distortion in Mn-O bonds, relieving the strain between layers, and reducing the occurrence of P3-O3 phase transition under high voltages. These findings are supported by EXAFS, in situ X-ray diffraction, advanced transmission electron microscopy, electron tomography, and DFT simulations. The low-strain K0.5Mn0.8Co0.1Zn0.1O2 electrode exhibits a high reversible capacity retention about ∼90 % (105 mAh g−1 at 100 mA g−1), exceptional rate performance in the voltage of 1.5 ∼ 3.9 V, and a substantial capacity retention after 500 cycles. This strain-relieved approach broadens the scope of lattice engineering by addressing internal strain concerns and mitigating the strain associated with potassium (de)intercalation, thereby having potential to advance the development of stable cathodes for PIBs.

Flame‐assisted ultrafast synthesis of functionalized carbon nanosheets for high‐performance sodium storage

AbstractThe unique structural features of hard carbon (HC) make it a promising anode candidate for sodium‐ion batteries (SIB). However, traditional methods of preparing HC require special equipment, long reaction times, and large energy consumption, resulting in low throughputs and efficiency. In our contribution, a novel synthesis method is proposed, involving the formation of HC nanosheets (NS‐CNs) within minutes by creating an anoxic environment through flame combustion and further introducing sulfur and nitrogen sources to achieve heteroatom doping. The effect of heterogeneous element doping on the microstructure of HC is quantitatively analyzed by high‐resolution transmission electron microscopy and image processing technology. Combined with density functional theory calculation, it is verified that the functionalized HC exhibits stronger Na+ adsorption ability, electron gain ability, and Na+ migration ability. As a result, NS‐CNs as SIB anodes provide an ultrahigh reversible capacity of 542.7 mAh g−1 at 0.1 A g−1, and excellent rate performance with a reversible capacity of 236.4 mAh g−1 at 2 A g−1 after 1200 cycles. Furthermore, full cell assembled with NS‐CNs as the can present 230 mAh g−1 at 0.5 A g−1 after 150 cycles. Finally, in/ex situ techniques confirm that the excellent sodium storage properties of NS‐CNs are due to the construction of abundant active sites based on the novel synthesis method for realizing the reversible adsorption of Na+. This work provides a novel strategy to develop novel carbons and gives deep insights for the further investigation of facile preparation methods to develop high‐performance carbon anodes for alkali‐ion batteries.

High-Pressure Freezing and Low-Temperature Processing of Seeds for Electron Microscopy and Electron Tomography.

High-pressure freezing/freeze substitution has been used to preserve biological samples for ultrastructure study instead of chemical fixation. For most plant samples, the water content is too high and cannot be properly preserved during cryofixation. Additionally, the cell wall is a barrier that prevents the substitution of water with the resin. In this chapter, we will discuss modified high-pressure freezing and subsequent processing protocols based on our routinely used methodology for examining Arabidopsis seeds in transmission electron microscopy and electron tomography.

GoldDigger and Checkers, computational developments in cryo-scanning transmission electron tomography to improve the quality of reconstructed volumes.

In this work, we present a pair of tools to improve the fiducial tracking and reconstruction quality of cryo-scanning transmission electron tomography (STET) datasets. We then demonstrate the effectiveness of these two tools on experimental cryo-STET data. The first tool, GoldDigger, improves the tracking of fiducials in cryo-STET by accommodating the changed appearance of highly defocussed fiducial markers. Since defocus effects are much stronger in scanning transmission electron microscopy than in conventional transmission electron microscopy, existing alignment tools do not perform well without manual intervention. The second tool, Checkers, combines image inpainting and unsupervised deep learning for denoising tomograms. Existing tools for denoising cryo-tomography often rely on paired noisy image frames, which are unavailable in cryo-STET datasets, necessitating a new approach. Finally, we make the two software tools freely available for the cryo-STET community.

Synthesis of nanocomposites of montmorillonite with carbon nanotubes as a potential material for water purification

The main goal of this research is to create nanocomposites based on unmodified and iron-modified (FeNP) montmorillonite (Mt) and carbon nanotubes (CNT) synthesized using the chemical vapor deposition method. The target area for the application of these materials is the creation of water treatment systems. This paper compares the efficiency of the CNT synthesis process on Mt before and after modification with FeNP of different concentrations and provides the characterization of the CNT microstructure and structure using different methods, such as scanning electron microscopy, high-resolution transmission electron imaging, and Raman spectroscopy. For initial verification of properties important for water purification, Mt+CNT and Mt+FeNP+CNT nanocomposites on a carbon nonwoven fabric (CF) are tested in this work. Incubation of the above-mentioned samples in a water–oil mixture reveals complex adsorption dynamics. The CF+Mt+FeNP+CNT sample shows a very good oil adsorption capacity due to its superhydrophobic and oleophilic properties.

An introduction to scanning transmission electron microscopy for the study of protozoans.

Since its inception in the 1930s, transmission electron microscopy (TEM) has been a powerful method to explore the cellular structure of parasites. TEM usually requires samples of <100 nm thick and with protozoans being larger than 1 μm, their study requires resin embedding and ultrathin sectioning. During the past decade, several new methods have been developed to improve, facilitate, and speed up the structural characterisation of biological samples, offering new imaging modalities for the study of protozoans. In particular, scanning transmission electron microscopy (STEM) can be used to observe sample sections as thick as 1 μm thus becoming an alternative to conventional TEM. STEM can also be performed under cryogenic conditions in combination with cryo-electron tomography providing access to the study of thicker samples in their native hydrated states in 3D. This method, called cryo-scanning transmission electron tomography (cryo-STET), was first developed in 2014. This review presents the basic concepts and benefits of STEM methods and provides examples to illustrate the potential for new insights into the structure and ultrastructure of protozoans.