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  • HAADF-STEM Image Resolution Enhancement Using High-Quality Image Reconstruction Techniques: Case of the Fe3O4(111) Surface
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-08-13
    G. Bárcena-González; M. P. Guerrero-Lebrero; E. Guerrero; A. Yañez; B. Nuñez-Moraleda; D. Kepaptsoglou; V. K. Lazarov; P. L. Galindo

    From simple averaging to more sophisticated registration and restoration strategies, such as super-resolution (SR), there exist different computational techniques that use a series of images of the same object to generate enhanced images where noise and other distortions have been reduced. In this work, we provide qualitative and quantitative measurements of this enhancement for high-angle annular dark-field scanning transmission electron microscopy imaging. These images are compared in two ways, qualitatively through visual inspection in real and reciprocal space, and quantitatively, through the calculation of objective measurements, such as signal-to-noise ratio and atom column roundness. Results show that these techniques improve the quality of the images. In this paper, we use an SR methodology that allows us to take advantage of the information present in the image frames and to reliably facilitate the analysis of more difficult regions of interest in experimental images, such as surfaces and interfaces. By acquiring a series of cross-sectional experimental images of magnetite (Fe3O4) thin films (111), we have generated interpolated images using averaging and SR, and reconstructed the atomic structure of the very top surface layer that consists of a full monolayer of Fe, with topmost Fe atoms in tetrahedrally coordinated sites.

    更新日期:2019-12-13
  • Electrochemical Behavior of Carbon Electrodes for In Situ Redox Studies in a Transmission Electron Microscope
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-10-24
    Robin Girod; Nikolaos Nianias; Vasiliki Tileli

    Electrochemical liquid cell transmission electron microscopy (TEM) is a unique technique for probing nanocatalyst behavior during operation for a range of different electrocatalytic processes, including hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), or electrochemical CO2 reduction (eCO2R). A major challenge to the technique's applicability to these systems has to do with the choice of substrate, which requires a wide inert potential range for quantitative electrochemistry, and is also responsible for minimizing background gas generation in the confined microscale environment. Here, we report on the feasibility of electrochemical experiments using the standard redox couple Fe(CN)63−/4− and microchips featuring carbon-coated electrodes. We electrochemically assess the in situ performance with respect to flow rate, liquid volume, and scan rate. Equally important with the choice of working substrate is the choice of the reference electrode. We demonstrate that the use of a modified electrode setup allows for potential measurements relatable to bulk studies. Furthermore, we use this setup to demonstrate the inert potential range for carbon-coated electrodes in aqueous electrolytes for HER, OER, ORR, and eCO2R. This work provides a basis for understanding electrochemical measurements in similar microscale systems and for studying gas-generating reactions with liquid electrochemical TEM.

    更新日期:2019-12-13
  • Quantitative Assessment of Anti-Cancer Drug Efficacy From Coregistered Mass Spectrometry and Fluorescence Microscopy Images of Multicellular Tumor Spheroids
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-10-01
    Jan Michálek; Karel Štěpka; Michal Kozubek; Jarmila Navrátilová; Barbora Pavlatovská; Markéta Machálková; Jan Preisler; Adam Pruška

    Spheroids—three-dimensional aggregates of cells grown from a cancer cell line—represent a model of living tissue for chemotherapy investigation. Distribution of chemotherapeutics in spheroid sections was determined using the matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI). Proliferating or apoptotic cells were immunohistochemically labeled and visualized by laser scanning confocal fluorescence microscopy (LSCM). Drug efficacy was evaluated by comparing coregistered MALDI MSI and LSCM data of drug-treated spheroids with LSCM only data of untreated control spheroids. We developed a fiducial-based workflow for coregistration of low-resolution MALDI MS with high-resolution LSCM images. To allow comparison of drug and cell distribution between the drug-treated and untreated spheroids of different shapes or diameters, we introduced a common diffusion-related coordinate, the distance from the spheroid boundary. In a procedure referred to as “peeling”, we correlated average drug distribution at a certain distance with the average reduction in the affected cells between the untreated and the treated spheroids. This novel approach makes it possible to differentiate between peripheral cells that died due to therapy and the innermost cells which died naturally. Two novel algorithms—for MALDI MS image denoising and for weighting of MALDI MSI and LSCM data by the presence of cell nuclei—are also presented.

    更新日期:2019-12-13
  • New Insights into the Ultrastructure of Bioapatite After Partial Dissolution: Based on Whale Rostrum, the Densest Bone
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-10-10
    Lingyi Tang; Li Zhang; Michael Yue; Da Tian; Mu Su; Zhen Li

    Mineral particles in bone are interlaced with collagen fibrils, hindering the investigation of bioapatite crystallites (BAp). This study utilized a special whale rostrum (the most highly mineralized bone ever recorded) to measure the crystallites of bone BAp via long-term dissolution in water. The BAp in the rostrum has a low solubility (6.7 ppm Ca and 3.8 ppm P after 150 days dissolution) as well as in normal bones, which leads to its Ksp value of ~10−53. Atomic force microscopy results show tightly compacted mineral crystallites and confirm the low amount of collagen in the rostrum. Additionally, the mineral crystallites demonstrate irregular plate-like shapes with variable sizes. The small crystallites (~11 × 24 nm) are easily detached from BAp prisms, compared with the large crystallites (~50 nm). Moreover, various orientations of crystallites are observed on the edge of the prisms, which suggest a random direction of mineral growth. Furthermore, these plate-like crystallites prefer to be stacked layer by layer under weak regulation from collagen. The morphology of rostrum after dissolution provides new insights into the actual morphology of BAp crystallites.

    更新日期:2019-12-13
  • Neutron Autoradiography Combined With UV-C Sensitization: Toward the Intracellular Localization of Boron
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-10-25
    Mario A. Gadan; Rodrigo Lloyd; Gisela Saint Martin; María S. Olivera; Lucía Policastro; Agustina M. Portu

    Our group has reported the imprint formation of biological material on polycarbonate nuclear track detectors by UV-C exposure, which is used as an approach to simultaneously visualize cell imprints and nuclear tracks coming from the boron neutron capture reaction. Considering that the cell nucleus has a higher UV-C absorption than the cytoplasm and that hematoxylin preferentially stains the nucleus, we proposed to enhance the contrast between these two main cell structures by hematoxylin staining before UV-C sensitization. In this study, several experiments were performed in order to optimize UV-C exposure parameters and chemical etching conditions for cell imprint formation using the SK-BR-3 breast cancer cell line. The proposed method improves significantly the resolution of the cell imprints. It allows clear differentiation of the nucleus from the rest of the cell, together with nuclear tracks pits. Moreover, it reduces considerably the UV-C exposure time, an important experimental issue. The proposed methodology can be applied to study the boron distribution independently from the chosen cell line and/or boron compounds.

    更新日期:2019-12-13
  • In Vivo Multivesicular Body and Exosome Secretion in the Intestinal Epithelial Cells of Turtles During Hibernation
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-10-28
    Waseem Ali Vistro; Yufei Huang; Xuebing Bai; Ping Yang; Abdul Haseeb; Hong Chen; Yifei Liu; Zhang Yue; Imran Tarique; Qiusheng Chen

    The present study was designed to investigate the in vivo biological processes of multivesicular bodies (MVBs) and exosomes in mitochondria-rich cells (MRCs), goblet cells (GCs), and absorptive cells (ACs) in turtle intestines during hibernation. The exosome markers, cluster of differentiation 63 (CD63) and tumor susceptibility gene 101 (TSG101), were positively expressed in intestinal villi during turtle hibernation. The distribution and formation processes of MVBs and exosomes in turtle MRCs, GCs, and ACs were further confirmed by transmission electron microscopy. During hibernation, abundantly secreted early endosomes (ees) were localized in the luminal and basal cytoplasm of the MRCs and ACs, and late endosomes (les) were dispersed with the supranuclear parts of the MRCs and ACs. Many “heterogeneous” MVBs were identified throughout the cytoplasm of the MRCs and ACs. Interestingly, the ees, les, and MVBs were detected in the cytoplasm of the GCs during hibernation; however, they were absent during nonhibernation. Furthermore, the exocytosis pathways of exosomes and autophagic vacuoles were observed in the MRCs, GCs, and ACs during hibernation. In addition, the number of different MVBs with intraluminal vesicles (ILVs) and heterogeneous endosome–MVB–exosome complexes was significantly increased in the MRCs, GCs, and ACs during hibernation. All these findings indicate that intestinal epithelial cells potentially perform a role in the secretion of MVBs and exosomes, which are essential for mucosal immunity, during hibernation.

    更新日期:2019-12-13
  • Effect of Ultra-Small Chitosan Nanoparticles Doped with Brimonidine on the Ultra-Structure of the Trabecular Meshwork of Glaucoma Patients
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-04-25
    Indu Barwal; Rahul Kumar; Tanuj Dada; Subhash Chandra Yadav

    Brimonidine, an anti-glaucoma medicine, acts as an adrenergic agonist which decreases the synthesis of aqueous humour and increases the amount of drainage through Schlemm's canal and trabecular meshwork, but shows dose-dependent (0.2% solution thrice daily) toxicity. To reduce the side effects and improve the efficacy, brimonidine was nanoencapsulated on ultra-small-sized chitosan nanoparticles (nanobrimonidine) (28 ± 4 nm) with 39% encapsulation efficiency, monodispersity, freeze–thawing capability, storage stability, and 2% drug loading capacity. This nanocomplex showed burst, half, and complete release at 0.5, 45, and 100 h, respectively. Nanobrimonidine did not show any in vitro toxicity and was taken up by caveolae-mediated endocytosis. The nanobrimonidine-treated trabeculectomy tissue of glaucoma patients showed better dilation of the trabecular meshwork under the electron microscope. This is direct evidence for better bioavailability of nanobrimonidine after topical administration. Thus, the developed nanobrimonidine has the potential to improve the efficacy, reduce dosage and frequency, and improve delivery to the anterior chamber of the eye.

    更新日期:2019-12-13
  • Role of Electron Microscopy in Early Detection of Altered Epithelium During Experimental Oral Carcinogenesis
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-03-14
    Sharada Sawant; Harsh Dongre; Deepak Kanojia; Sayli Jamghare; Anita Borges; Milind Vaidya

    Early detection of altered epithelium can help in controlling the further progression by timely intervention. Alterations in cellular adhesion are one of the hallmarks of cancer progression, which can be detected at the intracellular level using high-resolution electron microscopy. This study aimed to evaluate the role of electron microscopy in the establishment of ultrastructural markers for early detection of altered epithelium using tissues from 4-Nitroquinoline-1-Oxide (4NQO) induced rat tongue carcinogenesis. Our previous study using light microscopy displayed no histopathological alterations in 4NQO treated tissues until 40 days of treatment, while dysplasia, papilloma and carcinoma were detected at 80/120, 160 and 200 days, respectively. However, electron microscopy detected alterations such as detachment of desmosomes from cell membranes and their clustering in the cytoplasm, increased tonofilaments, keratohyaline granules and thickened corneum in 40 days treated corresponding tissues. These alterations are apparent with hyperkeratosis/hyperplasia but remained undetected using light microscopy. Further, in dysplasia, papilloma and carcinoma, gradual and significant loss of desmosomes, leading to the significant widening of intercellular spaces, was observed using iTEM software. These parameters may serve as indicators for progression of oral cancer. Our results highlight the importance of electron microscopy in the early detection of subcellular changes in the altered epithelium.

    更新日期:2019-12-13
  • Processing Techniques for Scanning Electron Microscopy Imaging of Giant Cells from Giant Cell Tumors of Bone
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-08-30
    Asit Ranjan Mridha; Indu Barwal; Abhishek Gupta; Abdul Majeed; Adarsh W. Barwad; Venkatesan Sampath Kumar; Shivanand Gamanagatti; Subhash Chandra Yadav

    Giant cell tumor (GCT) of bone is a common benign lesion that causes significant morbidity due to the failure of modern medical and surgical treatment. Surface ultra-structures of giant cells (GCs) may help in distinguishing aggressive tumors from indolent GC lesions. This study aimed to standardize scanning electron microscopic (SEM) imaging of GC from GCT of bone. Fresh GCT collected in Dulbecco's Modified Eagle Medium was washed to remove blood, homogenized, or treated with collagenase to isolate the GCs. Mechanically homogenized and collagenase-digested GCs were imaged on SEM after commonly used drying methodologies such as air-drying, tetramethylsilane (TMS)-drying, freeze-drying, and critical point-drying (CPD) for the optimization of sample processing. The collagenase-treated samples yielded a greater number of isolated GC and showed better surface morphology in comparison to mechanical homogenization. Air-drying was associated with marked cell shrinkage, and freeze-dried samples showed severe cell damage. TMS methodology partially preserved the cell contour and surface structures, although the cell shape was distorted. GC images with optimum surface morphology including membrane folding and microvesicular structures on the surface were observed only in collagenase-treated and critical point-dried samples. Collagenase digestion and critical point/TMS-drying should be performed for optimal SEM imaging of individual GCs.

    更新日期:2019-12-13
  • Microstructural Characterization of GaN Grown on SiC
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-08-01
    Sabyasachi Saha; Deepak Kumar; Chandan K. Sharma; Vikash K. Singh; Samartha Channagiri; Duggi V. Sridhara Rao

    GaN films have been grown on SiC substrates with an AlN nucleation layer by using a metal organic chemical vapor deposition technique. Micro-cracking of the GaN films has been observed in some of the grown samples. In order to investigate the micro-cracking and microstructure, the samples have been studied using various characterization techniques such as optical microscopy, atomic force microscopy, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy (TEM). The surface morphology of the AlN nucleation layer is related to the stress evolution in subsequent overgrown GaN epilayers. It is determined via TEM evidence that, if the AlN nucleation layer has a rough surface morphology, this leads to tensile stresses in the GaN films, which finally results in cracking. Raman spectroscopy results also suggest this, by showing the existence of considerable tensile residual stress in the AlN nucleation layer. Based on these various observations and results, conclusions or propositions relating to the microstructure are presented.

    更新日期:2019-12-13
  • Flower-Like MoS2 for Next-Generation High-Performance Energy Storage Device Applications
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-08-27
    Sumit Majumder; Sangam Banerjee

    Here, a well crystalline 3D flower-like structured MoS2 (~420 nm) has been successfully synthesized on a large scale by a simple hydrothermal technique. The evolution of morphology in the formation process has also been investigated. The crystallinity, purity, and morphology of the sample are characterized by powder X-ray diffraction, Fourier-transform infrared spectroscopy, fieldemission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) techniques. The FESEM and TEM images reveal that the sample exhibits a uniform 3D flower-like microsphere shape with folded nanosheets, which are stretched out along the edge of the microsphere. The electrochemical performance of the sample has been investigated by cyclic voltammogram, galvanostatic charge–discharge, and electrochemical impedance spectroscopy studies. The results of the electrochemical analysis suggest that the material delivers a maximum specific capacitance (Csp) of 350 F/g at a discharge current density of 0.25 A/g with energy density 17.5 Wh/kg. It also exhibits good capability and excellent cyclic stability (94% capacity retention after 1,000 cycles in 1 A/g) owing to the coupling effect of electrical conductivity with the interesting morphology and larger active surface area. Hence, the sample may be used as a promising electrode material for high-performance energy storage devices.

    更新日期:2019-12-13
  • Study of Crystallographic Texture Evolution during High-Temperature Deformation of 18Cr-ODS Ferritic Steel based on Plasticity Assessment
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-07-25
    Manmath Kumar Dash; R. Mythili; Rahul John; S. Saroja; Arup Dasgupta

    This paper aims at understanding the texture evolution in extruded oxide dispersion strengthened 18Cr ferritic steel during high-temperature uniaxial compression testing at 1,423 K at a strain rate of 0.01/s based on extensive electron back scatter diffraction characterization. The α-fiber texture is observed along the extrusion direction (ED) in the initial microstructure. The flow curves generated during uniaxial compression test are used to determine the associated hardening parameters. In addition, the degree of texture evolution after deformation along the ED and the transverse direction (TD) with respect to the initial condition has been predicted using VPSC-5 constitutive model. The prediction shows that the deformation along the ED produces a dominant γ-fiber texture in contrast to the TD. This is in agreement with the experimental results where γ-fiber texture is observed, due to enhanced dynamic recrystallization at high-temperature deformation.

    更新日期:2019-12-13
  • Metal Nanoparticle-Decorated Silicon Nanowire Arrays on Silicon Substrate and their Applications
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-09-13
    Abhijit Roy; Biswarup Satpati

    Herein, we report an efficient method to produce silver (Ag) nanoparticle-decorated silicon (Si) nanowire (NW) arrays on a pyramidal Si (P-Si) substrate by using a pure chemical method and rapid thermal annealing in different atmospheres. A metal-assisted chemical etching technique was used to produce vertical Si NW arrays on pyramidal Si. The etching was observed to be heavily dependent on the substrate type. On planar Si (100), the etching was observed to occur in a uniform manner. However, the etching rate was observed to increase from the top to the base of the Si pyramid. The Si NWs produced from P-Si have zig-zag sidewalls as observed from high-resolution transmission electron microscopy images. However, for the same oxidant concentration, Si NWs produced from planar Si (100) consist of straight and amorphous sidewalls. Local variation of oxidant concentration is responsible for the formation of different sidewalls. The substrates are both surface-enhanced Raman scattering (SERS) active and hydrophobic. The hydrophobicity is due to the dual scale of roughness contributed to by both pyramidal and NW structures. Finite-difference time-domain simulation shows that the gap between two Ag spheres and also the gap between Si NWs and Ag spheres contributed to SERS enhancement.

    更新日期:2019-12-13
  • Investigation of ORR Performances on Graphene/Phthalocyanine Nanocomposite in Neutral Medium
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-05-27
    Moumita Mukherjee; Madhupriya Samanta; Gour P. Das; Kalyan K. Chattopadhyay

    The drive to replace scarce and expensive Pt-based electrocatalysts for oxygen reduction reaction (ORR) has led to the development of a group of electrocatalysts composed of transition-metal ion centers coordinated with four nitrogen groups (M-N4). Among these, metal phthalocyanines (MPcs), due to low cost of preparation, highly conjugated structure as well as high thermal and chemical stability, have received a great interest. The catalytic activity of MPcs can be improved by employing conducting supports. Here, in this report, we have solvothermally synthesized graphene-supported zinc phthalocyanine nanostructures, and their ORR kinetics and mechanism have been investigated in neutral solution (pH = 7) by using the rotating disk electrode technique. The as-synthesized nanocomposite followed a 4e− reduction pathway. The onset potential (−0.04 V versus Ag/AgCl) found in this work can be comparable with other state-of-the-art material, demonstrating good performance in neutral solution. The fascinating performance leads the nanocomposite material toward future energy applications.

    更新日期:2019-12-13
  • Enhanced Photoluminescence Properties of Low-Dimensional Eu3+-Activated Y4Al2O9 Phosphor Compared to Bulk for Solid-State Lighting Applications and Latent Fingerprint Detection-Based Forensic Applications
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-04-26
    Antika Das; Subhajit Saha; Karamjyoti Panigrahi; Uttam Kumar Ghorai; Kalyan Kumar Chattopadhyay

    In recent years, nanoscale phosphors have become vital in optoelectronic applications and to understand the improved performance of nanophosphors over bulk material, detailed investigation is essential. Herein, trivalent europium-activated Y4Al2O9 phosphors were developed by solid-state reaction and solvothermal reaction methods and their performance as a function of their dimension was studied for various applications. Under 394 nm optical excitation, the photoluminescence (PL) emission, excited state lifetime of the nanophosphor, exhibits greater performance than its bulk counterpart. The homogeneous spherical structure of the nanophosphors as compared with solid lumps of bulk phosphors is the basis for almost 40% of the enhancement in nanophosphors' intense red emission compared to the bulk. Moreover, the thermal stability of the nanophosphor is much better than the bulk phosphor, which clearly indicates a key advantage of nanophosphor. The superior performance of Eu3+-doped Y4Al2O9 nanophosphors over their bulk counterparts has been demonstrated for industrial phosphor-converted light-emitting diodes and visualization of latent fingerprint.

    更新日期:2019-12-13
  • Hollow Silver Nanostructures: The Role of Capping Agents in Tailoring the Shape, Structure, and Plasmonic Properties
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-04-29
    Bhavesh Kumar Dadhich; Bhavya Bhushan; Amiya Priyam

    The shape- and structure-directing ability of capping agents, namely, acetic acid (AA) and folic acid (FA), has been analyzed in the synthesis of hollow plasmonic nanostructures via the nanoscale Kirkendall effect. FA was found to possess both shape-directing and structure-directing abilities when spherical solid Ag2O nanoparticles were transformed into hollow silver nanocubes (HAgNCs). In contrast, AA acted only as a structure-directing agent in the transformation from solid Ag2O nanospheres to hollow Ag nanospheres (HAgNSs). FA capping leads to enhanced plasmon tunability range from 535 to 640 nm in the hollow silver nanostructures. The size and shape of nanostructures were analyzed by high-resolution transmission electron microscopy (HRTEM). HRTEM revealed that the outer diameter of AA-capped HAgNSs is 50 ± 10 nm while edge-length for FA-capped HAgNCs is 100 ± 15 nm. The diameter of inner void space was found to be 30 ± 5 and 43 ± 5 nm for HAgNSs and HAgNCs, respectively. The phase purity of the hollow nanostructures was confirmed by X-ray diffraction and energy dispersive X-ray measurements. Due to unique structural and plasmonic features, FA-capped HAgNCs are well-suited for biomedical applications.

    更新日期:2019-12-13
  • Dirac States of 2D Topological Insulators: Effect of Heterovalent Dopant-Content
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-04-12
    Salma Khatun; Amlan J. Pal

    We have studied Bi2Se3 at its 2D-limit using scanning tunneling spectroscopy (STS). Bulk Bi2Se3 is a well-known topological insulator having gapless surface states. In the 2D limit, the interior of the material exhibits a band gap, whereas the periphery shows a gapless metallic state having a Dirac point. We demonstrate a method to tune the Fermi energy and hence the Dirac point of Bi2Se3 nanoplates through doping at the anionic site. For this purpose, STS measurements were carried out on the Bi2Se3 system. We have used bromide as a dopant, which turns the material to n-type in nature. As a result, STS studies infer that the Fermi energy (EF) shifted toward the conduction band and consequently the Dirac point could be found to move away from Fermi energy. Through STS measurements, we have demonstrated a correlation between the shift of Dirac point position and the dopant content. The size, shape, and compositions of Bi2Se3 nanoflakes and concentration of bromine in the doped nanostructures were determined using transmission electron microscopy, associated energy dispersive X-ray spectroscopy analysis, and X-ray diffraction.

    更新日期:2019-12-13
  • Effect of Heavy Mass Ion (Gold) and Light Mass Ion (Boron) Irradiation on Microstructure of Tungsten
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-05-28
    Prashant Sharma; Padivattathumana Maya; Satyaprasad Akkireddy; Prakash M. Raole; Anil K. Tyagi; Asha Attri; Pawan K. Kulriya; Parmendra K. Bajpai; Sudhir Mishra; Shiv P. Patel; Tarkeshwar Trivedi; K. B. Khan; Shishir P. Deshpande

    The difference in the defect structures produced by different ion masses in a tungsten lattice is investigated using 80 MeV Au7+ ions and 10 MeV B3+ ions. The details of the defects produced by ions in recrystallized tungsten foil samples are studied using transmission electron microscopy. Dislocations of type b = 1/2[111] and [001] were observed in the analysis. While highly energetic gold ion produced small clusters of defects with very few dislocation lines, boron has produced large and sparse clusters with numerous dislocation lines. The difference in the defect structures could be due to the difference in separation between primary knock-on atoms produced by gold and boron ions.

    更新日期:2019-12-13
  • Growth of Molybdenum Trioxide Nanoribbons on Oriented Ag and Au Nanostructures: A Scanning Electron Microscopy (SEM) Study
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-06-18
    Paramita Maiti; Arijit Mitra; R. R. Juluri; Ashutosh Rath; Parlapalli V Satyam

    We report the growth of molybdenum trioxide (MoO3) nanoribbons (NRs) on epitaxial Ag and oriented Au nanostructures (NSs) using an ultra-high vacuum (UHV)-molecular beam epitaxy (MBE) technique at different substrate temperatures. An approximately 2 nm silver (Ag) film has been deposited at different growth temperatures (using UHV-MBE) on cleaned Si(100), Si(110), and Si(111) substrates. For faceted Au NSs, an approximately 50 nm Au film has been deposited (using high-vacuum thermal evaporation) on a Si(100) substrate with a native oxide layer at the interface and the sample was annealed in low vacuum (≈10−2) and at high temperature (≈975°C). Scanning electron microscopy measurements were performed to determine the morphology of MoO3/Ag and MoO3/Au composite films. From energy dispersive X-ray spectroscopy elemental mapping and line scans it is found that faceted Au NSs are more favorable for the growth of MoO3 NRs than epitaxial Ag microstructures.

    更新日期:2019-12-13
  • Microstructural Characterization by Automated Crystal Orientation and Phase Mapping by Precession Electron Diffraction in TEM: Application to Hot Deformation of a γ-TiAl-based Alloy
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-04-11
    Vajinder Singh; Chandan Mondal; P. P. Bhattacharjee; P. Ghosal

    Microstructural evolution of a hot deformed γ-TiAl-based Ti–45Al–8Nb–2Cr–0.2B (at.%) alloy has been studied using an advanced characterization technique called automated crystal orientation and phase mapping by precession electron diffraction carried out in a transmission electron microscope (with a NanoMEGAS attachment). It has been observed that the technique, having a capability to recognize diffraction patterns with improved accuracy and reliability, is particularly suitable for characterization of complex microstructural features evolved during hot deformation of multiphase (α2 + γ + β)-based TiAl alloys. Examples of coupled orientations and phase maps of the present alloy demonstrate that the accurate reproduction of the very fine lamellar structure (α2 + γ + γ) is feasible due to its inherent high-spatial resolution and absence of a pseudo-symmetry effect. It enables identification of salient features of γ-TiAl deformation behavior in terms of misorientation analyses (GAM, GOS, and KAM) and transformation characteristics of very fine lamellar constituent phases. Apart from conventional strain analyses from the orientation database, an attempt has been made to image the dislocation sub-structure of γ-phases, which supplements the deformation structure evaluation using this new technique.

    更新日期:2019-12-13
  • Blue Emitting BaAl2O4:Ce3+ Nanophosphors with High Color Purity and Brightness for White LEDs
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-09-26
    Rituparna Chatterjee; Subhajit Saha; Karamjyoti Panigrahi; Uttam Kumar Ghorai; Gopes Chandra Das; Kalyan Kumar Chattopadhyay

    In this work, strongly blue emitting Ce3+-activated BaAl2O4 nanophosphors were successfully synthesized by a sol–gel technique. The crystal structure, morphology, and microstructure of the nanophosphors have been studied by X-ray powder diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy. The photoluminescence spectra show the impact of concentration variation of Ce3+ on the photoluminescence emission of the phosphor. These nanophosphors display intense blue emission peaking at 422 nm generated by the Ce3+ 5d → 4f transition under 350 nm excitation. Our results reveal that this nanophosphor has the capability to take part in the emergent domain of solid-state lighting and field-emission display devices.

    更新日期:2019-12-13
  • Micro-analytical Evidence of Copper-Based Pigment and Fungal Contamination of Medieval Mural Paintings in Beram, Croatia
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-09-27
    Tea Zubin Ferri; Emina Pustijanac; Ines Kovačić; Josipa Bilić

    The aim of the present study was to map the painting materials, degradation processes, and biological features present on the mural painting in the church of St. Mary in Beram (Croatia) to study their possible interaction and produce information helping the preservation of this valuable painting. The research was conducted on micro samples of painting materials taken from different sites along the painting and the characterization of the present fungal species was carried out. The painting samples, together with observable patinas and degradation products, were studied by optical microscopy (OM), scanning electron microscopy, energy-dispersive spectroscopy (SEM/EDS), Fourier-Transform Infrared spectroscopy, and powder X-ray diffraction. Fungal diversity was studied using cultivation methods followed by OM and SEM analyses in addition to molecular analysis. The results contribute to the characterization of the original painting materials, successively added materials and occurred interventions, to the understanding of degradation progressions and fungal biotransformation processes. A mineral, cumengite, a copper-based pigment extremely rarely used in art, was found. Its occurrence together with barium sulfate, gypsum, and calcium oxalate possibly produced by microbiological activity was studied and information was added regarding the composition of painting materials in St. Mary church mural cycle.

    更新日期:2019-12-13
  • Anatomy, Histology, and Ultrastructure of Salivary Glands of the Burrower Bug, Scaptocoris castanea (Hemiptera: Cydnidae)
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-10-01
    Jamile Fernanda Silva Cossolin; Luis Carlos Martínez; Monica Josene Barbosa Pereira; Lucia Madalena Vivan; Hakan Bozdoğan; Muhammad Fiaz; José Eduardo Serrão

    The burrower bug Scaptocoris castanea Perty, 1830 (Hemiptera: Cydnidae) is an agricultural pest feeding on roots of several crops. The histology and ultrastructure of the salivary glands of S. castanea were described. The salivary system has a pair of principal salivary glands and a pair of accessory salivary glands. The principal salivary gland is bilobed with anterior and posterior lobes joined by a hilus where an excretory duct occurs. The accessory salivary gland is tubular with a narrow lumen that opens into the hilus near the excretory duct, suggesting that its secretion is stored in the lumen of the principal gland. The cytoplasm of the secretory cells is rich in the rough endoplasmic reticulum, secretory vesicles with different electron densities and mitochondria. At the base of the accessory gland epithelium, there were scattered cells that do not reach the gland lumen, with the cytoplasm rich in the rough endoplasmic reticulum, indicating a role in protein production. Data show that principal and accessory salivary glands of S. castanea produce proteinaceous saliva. This is the first morphological description of the S. castanea salivary system that is similar to other Hemiptera Pentatomomorpha, but with occurrence of basal cells in the accessory salivary gland.

    更新日期:2019-12-13
  • A Simple and Rapid Staining Technique for Sex Determination of Trichinella Larvae Parasites by Confocal Laser Scanning Microscopy
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-10-28
    Inese Gavarane; Elena Kirilova; Ilze Rubeniņa; Ligita Mežaraupe; Sergejs Osipovs; Gunita Deksne; Aleksandrs Pučkins; Inese Kokina; Andrejs Bulanovs; Muza Kirjušina

    The roundworms of Trichinella genus are worldwide distributed and their prevalence in nature is high. Trichinella genus parasites are the causative agents of foodborne zoonosis trichinellosis. The main prevention and control of the infection are meat inspection by the magnetic stirrer method for the detection of Trichinella larvae in muscle samples. The treatment can be effective if the parasite is discovered early in the intestinal phase. Once the Trichinella larva has reached the muscle tissue, the parasite remains therein and there is no treatment for this life cycle stage. The Trichinella species is dioecious with separate male and female individuals. The developed staining technique that uses confocal laser scanning microscopy (CLSM) displays sufficient results for Trichinella larvae examination and this protocol is applicable to study the internal and external structures and for the sex determination of T. britovi and T. spiralis larvae samples. In the present study, a luminescent derivative was synthesized and used for staining of T. spiralis and T. britovi larvae samples for the examination by CLSM. Various fixatives, such as AFA, 70% ethanol, and Bouin's and Carnoy's solutions were tested for sample preparation. The synthesized luminescent compound demonstrates best visualization results for samples fixed in Bouin's fixative.

    更新日期:2019-12-13
  • Evaluation and Microanalysis of Parasitic and Bacterial Agents of Egyptian Fresh Sushi, Salmo salar
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-11-13
    Sara S. Abdel-Hakeem; Ghada Abd-Elmonsef Mahmoud; Hanan H. Abdel-Hafeez

    The present study aimed to evaluate the quality of fresh sushi in Egypt. Fifty samples of sushi (Salmo salar) were collected from restaurants in Alexandria, Egypt. Paraffin, semi-thin and ultra-thin sections were used for parasitological analysis by light and transmission electron microscopy. Bacteria were isolated by the dilution plate and direct plate methods and identified by a Vitek system. Twenty (40%) of the total examined samples showed microsporidia and helminth metacercariae infections. Histochemical stains showed distinct pinkish-red pyriform microspores embedded in muscular tissue stained with Gram, periodic acid-Schiff (PAS), and Ziehl–Neelsen (ZN) stains. Semi-thin sections showed double membrane xenoma-inducing granulomas containing spores at different developmental stages. Empty sporophorous vesicles and free spores were observed in the electron microscopic images. A bacteriological assay showed forty samples (80%) contaminated with human pathogenic bacteria with the average total bacterial counts ranging from 32 to 526 CFU/g. Four species of human pathogenic bacteria were identified in the examined samples, namely Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus, and Serratia plymuthica in 40, 38, 11, and 6 samples, respectively. These constitute the first record of fresh sushi product in Egypt and indicate the potential pathogenicity associated with raw seafood products.

    更新日期:2019-12-13
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  • Electron-Excited X-ray Microanalysis by Energy Dispersive Spectrometry at 50: Analytical Accuracy, Precision, Trace Sensitivity, and Quantitative Compositional Mapping
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-08-23
    Dale E. Newbury, Nicholas W.M. Ritchie

    2018 marked the 50th anniversary of the introduction of energy dispersive X-ray spectrometry (EDS) with semiconductor detectors to electron-excited X-ray microanalysis. Initially useful for qualitative analysis, EDS has developed into a fully quantitative analytical tool that can match wavelength dispersive spectrometry for accuracy in the determination of major (mass concentration C > 0.1) and minor (0.01 ≤ C ≤ 0.1) constituents, and useful accuracy can extend well into the trace (0.001 < C < 0.01) constituent range even when severe peak interference occurs. Accurate analysis is possible for low atomic number elements (B, C, N, O, and F), and at low beam energy, which can optimize lateral and depth spatial resolution. By recording a full EDS spectrum at each picture element of a scan, comprehensive quantitative compositional mapping can also be performed.

    更新日期:2019-10-22
  • Atomic Force Microscopy (AFM) Analysis of an Object Larger and Sharper than the AFM Tip
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-07-16
    Zhe Chen, Jiawei Luo, Ivo Doudevski, Sema Erten, Seong H. Kim

    Atomic force microscopy (AFM) is typically used for analysis of relatively flat surfaces with topographic features smaller than the height of the AFM tip. On flat surfaces, it is relatively easy to find the object of interest and deconvolute imaging artifacts resulting from the finite size of the AFM tip. In contrast, AFM imaging of three-dimensional objects much larger than the AFM tip height is rarely attempted although it could provide topographic information that is not readily available from two-dimensional imaging, such as scanning electron microscopy. In this paper, we report AFM measurements of a vertically-mounted razor blade, which is taller and sharper than the AFM tip. In this case, the AFM height data, except for the data collected around the cutting edge of the blade, reflect the shape of the AFM tip. The height data around the apex area are effectively the convolution of the AFM tip and the blade cutting edge. Based on computer simulations mimicking an AFM tip scanning across a round sample, a simple algorithm is proposed to deconvolute the AFM height data of an object taller and sharper than the AFM tip and estimate its effective curvature.

    更新日期:2019-10-22
  • Electron Probe Microanalysis Through Coated Oxidized Surfaces
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-07-16
    Mike B. Matthews, Ben Buse, Stuart L. Kearns

    Low voltage electron probe microanalysis (EPMA) of metals can be complicated by the presence of a surface oxide. If a conductive coating is applied, analysis becomes one of a three-layer structure. A method is presented which allows for the coating and oxide thicknesses and the substrate intensities to be determined. By restricting the range of coating and oxide thicknesses, tc and to respectively, x-ray intensities can be parameterized using a combination of linear functions of tc and to. tc can be determined from the coating element k-ratio independently of the oxide thickness. to can then be derived from the O k-ratio and tc. From tc and to the intensity components of the k-ratios from the oxide layer and substrate can each be derived. Modeled results are presented for an Ag on Bi2O3 on Bi system, with tc and to each ranging from 5 to 20 nm, for voltages of 5–20 kV. The method is tested against experimental measurements of Ag- or C-coated samples of polished Bi samples which have been allowed to naturally oxidize. Oxide thicknesses determined both before and after coating with Ag or C are consistent. Predicted Bi Mα k-ratios also show good agreement with EPMA-measured values.

    更新日期:2019-10-22
  • Determining the Volume Expansion at Grain Boundaries Using Extended Energy-Loss Fine Structure Analysis
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-08-13
    Proloy Nandi, James M. Howe

    Grain boundaries (GBs) play an important role in material behavior, so considerable effort has gone into determining their structure and properties. Studies of GBs have revealed a correlation between the GB energy and expansion of the planes normal to the GB, or the so-called normal volume expansion. In this investigation, the volume expansion at several GBs was experimentally determined using extended energy-loss fine structure (EXELFS) analysis in a scanning/transmission electron microscope, allowing changes in the nearest-neighbor (n.n.) distances to be determined with nanometer spatial resolution. EXELFS performed on three-model GBs showed that the average n.n. distances at the GBs increased with increasing GB energy. Additionally, the total volume expansion at the GBs, calculated using complementary plasmon energy profiles, showed excellent agreement with volume expansions measured using other experimental techniques. Hence, this study demonstrates that EXELFS is a useful technique to measure the normal volume expansion at GBs. When combined with the results from complementary studies on the same GBs using valence electron energy-loss spectroscopy, this work further shows that the GB energy increases in relation to both the decrease in electron density at the GB and an accompanying increase in specific volume expansion at the GB.

    更新日期:2019-10-22
  • Image Segmentation for FIB-SEM Serial Sectioning of a Si/C–Graphite Composite Anode Microstructure Based on Preprocessing and Global Thresholding
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-08-07
    Dongjae Kim, Sihyung Lee, Wooram Hong, Hyosug Lee, Seongho Jeon, Sungsoo Han, Jaewook Nam

    The choice of materials that constitute electrodes and the way they are interconnected, i.e., the microstructure, influences the performance of lithium-ion batteries. For batteries with high energy and power densities, the microstructure of the electrodes must be controlled during their manufacturing process. Moreover, understanding the microstructure helps in designing a high-performance, yet low-cost battery. In this study, we propose a systematic algorithm workflow for the images of the microstructure of anodes obtained from a focused ion beam scanning electron microscope (FIB-SEM). Here, we discuss the typical issues that arise in the raw FIB-SEM images and the corresponding preprocessing methods that resolve them. Next, we propose a Fourier transform-based filter that effectively reduces curtain artifacts. Also, we propose a simple, yet an effective, global-thresholding method to identify active materials and pores in the microstructure. Finally, we reconstruct the three-dimensional structures by concatenating the segmented images. The whole algorithm workflow used in this study is not fully automated and requires user interactions such as choosing the values of parameters and removing shine-through artifacts manually. However, it should be emphasized that the proposed global-thresholding method is deterministic and stable, which results in high segmentation performance for all sectioning images.

    更新日期:2019-10-22
  • Investigation of Electron Momentum Density in Carbon Nanotubes Using Transmission Electron Microscopy
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-09-04
    Zhenbao Feng, Hefu Li, Zongliang Wang, Xiaoyan Zhang, Hengshuai Li, Haiquan Hu, Dangsheng Su

    Valence Compton profiles (CPs) of multiwall (MWCNTs) and single-wall carbon nanotubes (SWCNTs) were obtained by recording electron energy-loss spectra at large momentum transfer in the transmission electron microscope, a technique known as electron Compton scattering from solids (ECOSS). The experimental MWCNT/SWCNT results were compared with that of graphite. Differences between the valence CPs of MWCNTs and SWCNTs were observed, and the SWCNT CPs indicate a greater delocalization of the ground-state charge density compared to graphite. The results clearly demonstrate the feasibility and potential of the ECOSS technique as a complementary tool for studying the electronic structure of materials with nanoscale spatial resolution.

    更新日期:2019-10-22
  • Carrier-Transport Study of Gallium Arsenide Hillock Defects
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-09-02
    Chuanxiao Xiao, Chun-Sheng Jiang, Jun Liu, Andrew Norman, John Moseley, Kevin Schulte, Aaron J. Ptak, Brian Gorman, Mowafak Al-Jassim, Nancy M. Haegel, Helio Moutinho

    Single-crystalline gallium arsenide (GaAs) grown by various techniques can exhibit hillock defects on the surface when sub-optimal growth conditions are employed. The defects act as nonradiative recombination centers and limit solar cell performance. In this paper, we applied near-field transport imaging to study hillock defects in a GaAs thin film. On the same defects, we also performed near-field cathodoluminescence, standard cathodoluminescence, electron-backscattered diffraction, transmission electron microscopy, and energy-dispersive X-ray spectrometry. We found that the luminescence intensity around the hillock area is two orders of magnitude lower than on the area without hillock defects in the millimeter region, and the excess carrier diffusion length is degraded by at least a factor of five with significant local variation. The optical and transport properties are affected over a significantly larger region than the observed topography and crystallographic and chemical compositions associated with the defect.

    更新日期:2019-10-22
  • Exploring the Parameter Space of Point Spread Function Determination for the Scanning Electron Microscope—Part I: Effect on the Point Spread Function
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-08-27
    Mandy C. Nevins, Kathryn Quoi, Richard K. Hailstone, Eric Lifshin

    The point spread function (PSF) of the scanning electron microscope (SEM) can be determined using a recently developed nanoparticle calibration method. Many parameters are involved in PSF determination and introduce a previously unstudied amount of uncertainty into the PSF size and shape. Signal type, support material thickness, reference particle size, PSF smoothing (K), and background correction were investigated regarding their effect on the PSF. Experimental data were complemented by CASINO simulations. Differences in detector position between the observed particles and the method's simulated reference particles caused shifting between secondary electron PSFs and backscattered electron PSFs. Support material thickness did not have a practical effect on the PSF at the tested voltages. Uncertainty in reference particle size varied the PSF full width at half maximum (FWHM) within ±0.7 nm at 2σ, with virtually no uncertainty in some cases. K and background correction within a reasonable range of values resulted in PSF FWHM differences within ±0.9 nm, except at 2 kV for K with an upper bound of ±1.9 nm due to increased noise. Tailoring K and background correction case-by-case would result in smaller differences. The interconnection of these parameters may help in future efforts to calculate their best selection.

    更新日期:2019-10-22
  • Exploring the Parameter Space of Point Spread Function Determination for the Scanning Electron Microscope—Part II: Effect on Image Restoration Quality
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-08-30
    Mandy C. Nevins, Richard K. Hailstone, Eric Lifshin

    Point spread function (PSF) deconvolution is an attractive software-based technique for resolution improvement in the scanning electron microscope (SEM) because it can restore information which has been blurred by challenging operating conditions. In Part 1, we studied a modern PSF determination method for SEM and explored how various parameters affected the method's ability to accurately estimate the PSF. In Part 2, we extend this exploration to PSF deconvolution for image restoration. The parameters include reference particle size, PSF smoothing (K), background correction, and restoration denoising (λ). Image quality was assessed by visual inspection and Fourier analysis. Overall, PSF deconvolution improved image quality. Low λ enhanced image sharpness at the cost of noise, while high λ created smoother restorations with less detail. λ should be chosen to balance feature preservation and denoising based on the application. Reference particle size within ±0.9 nm and K within a reasonable range had little effect on restoration quality. Restorations using background-corrected PSFs had superior quality compared with using no background correction, but if the correction was too high, the PSF was cut off causing blurrier restorations. Future efforts to automatically determine parameters would remove user guesswork, improve this method's consistency, and maximize interpretability of outputs.

    更新日期:2019-10-22
  • Adipocytes Migration is Altered Through Differentiation
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-07-30
    Maayan Lustig, Yuliya Zadka, Irena Levitsky, Amit Gefen, Dafna Benayahu

    Adipogenesis is a developmental process in which an elongated preadipocyte differentiates to a round adipocyte along with the accumulation of lipid droplets. In the present study, we focus on the study of cell motility at the single-cell level, toward expanding our knowledge regarding the cytoskeleton alteration during differentiation; since-cell motility is mediated by cytoskeletal components. We used the holographic-microscopy live imaging technique to evaluate, for the first time in the literature, differences between the motility of nondifferentiated preadipocytes and differentiated mature adipocytes in living cell cultures over time. We revealed that mean motility speed of preadipocytes was significantly higher (fourfold) than that of adipocytes, and that the movement of preadipocytes is less consistent and more extensive. Furthermore, we found that preadipocytes tend to migrate to farther distances, while mature adipocytes remain relatively close to their original location. The results presented here are in agreement with the fact that the cytoskeleton of adipocytes is altered during differentiation and similarly, points to the fact that the cell-sensing mechanisms are changing during differentiation. Our research paves the way to gain better insights of the differentiation process and its implications on larger scale systems in the context of obesity.

    更新日期:2019-10-22
  • Investigation on the Dependency of Phase Retrieval Accuracy Versus Edge Enhancement to the Noise Ratio of X-ray Propagation-Based Phase-Contrast Imaging
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-08-13
    Lin Zhang, Huijuan Zhao, Jingying Jiang, Limin Zhang, Jiao Li, Feng Gao, Zhongxing Zhou

    Phase retrieval is necessary for propagation-based phase-contrast imaging (PB-PCI). Arhatari established a model for predicting the impact of the sample-to-detector distance and the system noise on the phase retrieval performance. We have extended Arhatari's model to account for the parameters of excessive source size, finite detector resolution, and geometrical magnification for more practical cases. However, there exist interaction effects among these parameters resulting in difficulty of predicting the phase retrieval performance. In this study, we found that optimizing the trade-off among these parameters for phase retrieval is consistent with the improvement of edge enhancement to noise ratio (EE/N) in the “forward problem” of the PB-PCI. Hence, we engaged in establishing a relationship between EE/N and phase retrieval performance in terms of the “forward problem” and “inverse problem” of the PB-PCI, respectively. Our results showed that, at fixed detector resolution, phase retrieval from the phase-contrast projections at the same EE/N level resulted in the consistent phase retrieval performance. Therefore, the performance of phase retrieval can be predicted based on the EE/N level and be quantitatively optimized by increasing EE/N.

    更新日期:2019-10-22
  • Anatomical, Phytochemical, and Histochemical Study of Juniperus rigida Needles at Different Altitudes
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-08-27
    Shun Kuang, Linfang Liu, Mingliang Qing, Yujia Zhang, Xueping Feng, Dongmei Wang, Yun Jiang, Xin Zhang, Dengwu Li

    Needles of Juniperus rigida are used in Chinese traditional medicine for the treatment of brucellosis, dropsy, skin disease, and rheumatoid arthritis. This is the first study that reports anatomical structures of the J. rigida needles collected at different altitudes. The most common anatomical, phytochemical, and histochemical techniques and methods are used. The results show that anatomical structures and chemical composition change significantly at different altitudes. The main anatomical characters are significant xeromorphic structures (thick epidermis, hypodermis, and cuticle), a stomatal band, a developed vascular bundle, and a marginal resin duct. The xeromorphic structures become more pronounced with increasing altitude. The phytochemical and histochemical results demonstrate that the content of the main chemical compounds (phenols and terpenoids) basically increases at a higher elevation. Histochemical analysis localizes the phenols in epidermal cells, sponge tissue, endothelial layer cells, and stomatal bands, and the terpenoids in palisade tissue, sponge tissue, and the edge of the resin duct. This work reveals the relation between anatomy and chemistry in J. rigida needles, contributes to the quality control of its ethno-medicine, and provides the evidence to develop the commercial cultivation.

    更新日期:2019-10-22
  • Elucidation of Differential Nano-Textural Attributes for Normal Oral Mucosa and Pre-Cancer
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-09-17
    Debaleena Nawn, Saunak Chatterjee, Anji Anura, Swarnendu Bag, Debjani Chakraborty, Mousumi Pal, Ranjan Rashmi Paul, Jyotirmoy Chatterjee

    Computational analysis on altered micro-nano-textural attributes of the oral mucosa may provide precise diagnostic information about oral potentially malignant disorders (OPMDs) instead of an existing handful of qualitative reports. This study evaluated micro-nano-textural features of oral epithelium from scanning electron microscopic (SEM) images and the sub-epithelial connective tissue from light microscopic (LM) and atomic force microscopic (AFM) images for normal and OPMD (namely oral sub-mucous fibrosis, i.e., OSF). Objective textural descriptors, namely discrete wavelet transform, gray-level co-occurrence matrix (GLCM), and local binary pattern (LBP), were extracted and fed to standard classifiers. Best classification accuracy of 87.28 and 93.21%; sensitivity of 93 and 96%; specificity of 80 and 91% were achieved, respectively, for SEM and AFM. In the study groups, SEM analysis showed a significant (p < 0.01) variation for all the considered textural descriptors, while for AFM, a remarkable alteration (p < 0.01) was only found in GLCM and LBP. Interestingly, sub-epithelial collagen nanoscale and microscale textural information from AFM and LM images, respectively, were complementary, namely microlevel contrast was more in normal (0.251) than OSF (0.193), while nanolevel contrast was more in OSF (0.283) than normal (0.204). This work, thus, illustrated differential micro-nano-textural attributes for oral epithelium and sub-epithelium to distinguish OPMD precisely and may be contributory in early cancer diagnostics.

    更新日期:2019-10-22
  • Bee Venom Stimulates Hormone Secretion in Rat Somatotroph and Corticotroph Cells: Digital Image Analysis of Secretory Granules
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-09-17
    Adrian Florea, Fares Abu El Hof, Georgeta Maria Hazi, Marius Cristian Oprea

    In this study, we characterized secretory granules in somatotroph (STCs) and corticotroph (CTCs) cells from the anterior pituitary of rats, in conjunction with different experimental treatments with bee venom (BV). In the rats injected for 30 days with daily BV doses equivalent to one sting, we found significant changes in secretory granules' diameter: reduced by 48.15% in STCs and increased by 5.09% in CTCs, and especially a shift to gray into their intensity profile: increased by 237.04% in STCs and by 212.38% in CTCs. In the rats injected with a single high BV dose, the granules' diameter was reduced in both STCs (by 7.14%) and CTCs (by 4.67%—significant) and their gray intensity profile increased by 200% in STCs and by 51.71% in CTCs (both are significant). The changes in the gray profile reflected a reduced content of granules in the cells, consistent with an increase of the plasma levels of GH and ACTH in all cases. We concluded that the reduced hormone cargo of granules in STCs and CTCs resulted from an accelerated cell secretion. The results obtained for the two types of cells correlated, indicating a similar reaction of these secretory cells to the prolonged and acute presence of BV in the organism.

    更新日期:2019-10-22
  • Onset of Appearance and Potential Significance of Telocytes in the Developing Fetal Lung
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-09-16
    Mahmoud Awad, Wafaa Gaber, Dalia Ibrahim

    CD34, vimentin, and vascular endothelial growth factor immunohistochemical analysis and electron microscopic tools were employed to record the initial appearance of telocytes (TCs) and stage-by-stage variations in TC localizations in the developing rabbit lung. TCs could not be identified in the primitive embryonic lung until day 18 of gestation. In the pseudoglandular lung, CD34+ TCs had been recorded under the cartilage of the main bronchus, in the wall of large-sized pulmonary vessels and large epithelial tubes. In the canalicular phase, TCs could be demonstrated in the smooth muscle layer of the bronchioles including the terminal ones. The strength of CD34 immunoreactive signals had been amplified by age until the day of parturition. Ultrastructurally, TCs consisted of a tiny body and exceptionally long telopodes (Tps). The Tp consisted of alternating thin segments (podomers) and dilated ones (podoms). The Tp sometimes branched with a dichotomous pattern. TCs interconnected in a network either by homocellular junctions with neighboring TCs or by heterocellular junctions with smooth muscle cells and alveolar cells. Collectively, early detection of TCs in pulmonary vessels suggests a potential role for TCs in their angiogenesis. For the lung tissue, TCs seem to be involved in the regulation of lung histogenesis.

    更新日期:2019-10-22
  • Microscopic Assessment of Dead Cell Ratio in Cryopreserved Chicken Primordial Germ Cells
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-09-18
    Andrea Svoradová, Alexander Makarevich, Jaromír Vašíček, Lucia Olexiková, Sasa Dragin, Peter Chrenek

    This study aimed to compare three methods of cell death assessment [trypan blue exclusion (TBE), propidium iodide viability assay (PIVA), and transmission electron microscopy] to evaluate fresh and frozen–thawed chicken primordial germ cells (PGCs). For this study, chicken PGCs were collected from ROSS 908 and Oravka breed hens, cryopreserved-thawed according to the protocol, and submitted for different cell death assessments. We observed significant differences between TBE and PIVA techniques in the detectable proportion of dead cells in fresh (14.14 ± 1.27 versus 7.16 ± 1.02%, respectively) and frozen–thawed (44.00 ± 2.11 versus 33.33 ± 1.67%, respectively) samples of the Oravka breed. Moreover, significant differences (p < 0.05) between TBE and PIVA techniques in the detectable proportion of dead cells in fresh (9.20 ± 0.60 versus 5.37 ± 0.51%) samples of ROSS 908 breed were recorded. Differences may be due to methodological, sensitivity, and toxicity features of each technique tested, where TB stains cell cytoplasm of dead cells and PI penetrates and intercalates into DNA of dead cells. Therefore, we suggest using a more precise and sensitive PIVA for viability evaluation of PGCs. Further research is needed to apply various fluorochromes for more detailed cell viability evaluation.

    更新日期:2019-10-22
  • Functional Validation of DownRegulated MicroRNAs in HeLa Cells Treated with Polyalthia longifolia Leaf Extract Using Different Microscopic Approaches: A Morphological Alteration-Based Validation
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-08-06
    Shanmugapriya, Soundararajan Vijayarathna, Sreenivasan Sasidharan

    Several microscopy methods have been developed to assess the morphological changes in cells in the investigations of the mode of cell death in response to a stimulus. Our recent finding on the treatment of the IC50 concentration (26.67 μg/mL) of Polyalthia longifolia leaf extract indicated the induction of apoptotic cell death via the regulation of miRNA in HeLa cells. Hence, the current study was conducted to validate the function of these downregulated microRNAs in P. longifolia-treated HeLa cells using microscopic approaches. These include scanning electron microscope (SEM), transmission electron microscope (TEM), and acridine orange/propidium iodide (AO/PI)-based fluorescent microscopy techniques by observing the morphological alterations to cells after transfection with mimic miRNA. Interestingly, the morphological changes observed in this study demonstrated the apoptotic hallmarks, for instance, cell blebbing, cell shrinkage, cytoplasmic and nuclear condensation, vacuolization, cytoplasmic extrusion, and the formation of apoptotic bodies, which proved the role of dysregulated miRNAs in apoptotic HeLa cell death after treatment with the P. longifolia leaf extract. Conclusively, the current study proved the crucial role of downregulated miR-484 and miR-221-5p in the induction of apoptotic cell death in P. longifolia-treated HeLa cells using three approaches—SEM, TEM, and AO/PI-based fluorescent microscope.

    更新日期:2019-10-22
  • Immunohistochemical and Ultrastructural Features of the Seasonal Changes in the Epididymal Epithelium of Camel (Camelus dromedarius)
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-09-23
    Dalia Ibrahim, Fatma M. Abdel-Maksoud

    In order to evaluate the influence of reproductive activity on the functional role of the epididymal epithelium in the Egyptian dromedary camel, Connexin-43 (Cx-43), vascular endothelial growth factor (VEGF), and androgen receptor (AR) immunoreactivity in the epididymal epithelium and the fine structure of the principal, dark, basal, apical, and halo cells were investigated. The secretory activity of the principal cells was amplified in the breeding season, while its endocytotic function became more active in the nonbreeding season. This was evidenced by punctate strong immunoreactive signals for Cx-43, which appeared to be more intense in the apical region of these epithelial cells, and the extremely long slender stereocilia (microvilli) with multiple junctional complexes. The nonbreeding principal cells revealed granular immunoreactive signals for VEGF scattered in the apical and basal cytoplasm. Ultrastructurally, both extreme vacuolation and several multivesicular inclusion bodies were observed in their cytoplasm. Dark cell size greatly diminished in the nonbreeding season and their nuclear morphology greatly changed from oval to lobulated shape. The plasma membrane of the apical cells expressed several infoldings (microvilli) in the breeding season. However, it was almost smooth in the nonbreeding season except for a small microvillus that appeared as a bleb-like projection. In some regions, a strong dense immunoreactivity for VEGF could be recognized in the cytoplasm of the apical cells and some basal ones. Halo cells with numerous multivesicular inclusions occupying most of the cytoplasm and a lobulated eccentric nucleus were detected in the nonbreeding season. In conclusion, these findings indicate that the reproductive activity has a significant impact on the immunohistochemical and ultrastructural profiles of the epithelial cells lining the Egyptian dromedary camel epididymis.

    更新日期:2019-10-22
  • Cellular Invasion and Matrix Degradation, a Different Type of Matrix-Degrading Cells in the Cartilage of Catfish (Clarias gariepinus) and Japanese Quail Embryos (Coturnix coturnix japonica)
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-10-04
    Soha A. Soliman, Basma Mohamed Kamal, Hanan H. Abd-Elhafeez

    We previously studied the phenomena of the mesenchymal cell-dependent mode of cartilage growth in quail and catfish. Thus, we selected the two cartilage models in which mesenchymal cells participate in their growth. In such models, cartilage degradation occurred to facilitate cellular invasion. The studies do not explain the nature of the cartilage degrading cells. The current study aims to explore the nature of the cartilage-degrading cells using transmission electron microscopy (TEM) and immunohistochemistry. Samples of cartilage have been isolated from the air-breathing organ of catfish and the cartilage of the prospective occipital bone of quail embryos. Samples have been processed for TEM and immunohistochemistry. We found that two different cell types are involved in cartilage degradation; the macrophage in the cartilage of catfish and mesenchymal cells in the cartilage of the quail. Areas of cellular invasion in both catfish cartilage and quail embryo cartilage had an immunological affinity for MMP-9. In catfish, cartilage-degrading cells had identical morphological features of macrophages, whereas in quail embryos, cartilage-degrading cells were mesenchymal-like cells which had cell processes rich in vesicles and expressed CD117. Further study should consider the role of macrophage and mesenchymal cells during cartilage degradation. This could be valuable to be applied to remove the defective cartilage matrix formed in osteoarthritic patients to improve cartilage repair strategies.

    更新日期:2019-10-22
  • 更新日期:2019-10-22
  • Hydrotalcite Can Prevent the Damaging Effects of Helicobacter Pylori on Gastric Epithelial Cells—CORRIGENDUM
    Microsc. Microanal. (IF 2.673) Pub Date : 2019-07-29
    Yanyan Shi, Yanlei Guo, Ting Zhang, Shigang Ding

    Background: Helicobacter pylori is a major cause of gastric diseases including gastric cancer. This study was aimed to explore whether hydrotalcite can inhibit H. pylori infection of gastric epithelial cells. Methods: the gastric epithelial cell line GES-1 and the gastric cancer cell line BGC823 were infected with H. pylori at multiplicities of infections (MOIs) of 50:1 and 100:1. Hydrotalcite was added to cell cultures. Cell apoptosis and cell cycle analysis were performed to measure the situation of cell growth. The main changes of cell ultrastructure were observed by transmission electron microscopy. H. pylori cell adhesion was observed by scanning electron microscopy. Results: hydrotalcite could significantly inhibit cell apoptosis of GES-1 and cell proliferation of BGC823 induced by H. pylori infection at an MOI of 50:1. Hydrotalcite treatment protected gastric cells from H. pylori infection, and H. pylori adhesion to gastric cells was reduced. However, hydrotalcite could not reverse damage induced by H. pylori infection at an MOI of 100:1. Conclusion: hydrotalcite can protect gastric cells from H. pylori infection when cell damage is not serious. It can weaken the damage of cells induced by H. pylori and decrease H. pylori adhesion to gastric cells.

    更新日期:2019-10-22
  • 更新日期:2019-10-22
  • 更新日期:2019-10-22
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