scholarly journals Characterizing the Xenoma of Vairimorpha necatrix Provides Insights Into the Most Efficient Mode of Microsporidian Proliferation

2021 ◽  
Vol 11 ◽  
Author(s):  
Tian Li ◽  
Zhuoya Fang ◽  
Qiang He ◽  
Chunxia Wang ◽  
Xianzhi Meng ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Muscle Cells ◽  
High Electron ◽  
Scanning Electronic Microscopy ◽  
High Concentration ◽  
Transmission Electron ◽  
Intracellular Parasites ◽  
Infection Source ◽  
High Level

Microsporidia are a group of obligated intracellular parasites that can infect nearly all vertebrates and invertebrates, including humans and economic animals. Microsporidian Vairimorpha necatrix is a natural pathogen of multiple insects and can massively proliferate by making tumor-like xenoma in host tissue. However, little is known about the subcellular structures of this xenoma and the proliferation features of the pathogens inside. Here, we characterized the V. necatrix xenoma produced in muscle cells of silkworm midgut. In result, the whitish xenoma was initially observed on the 12th day post infection on the outer surface of the midgut and later became larger and numerous. The observation by scanning electronic microscopy showed that the xenoma is mostly elliptical and spindle with dense pathogen-containing protrusions and spores on the surface, which were likely shedding off the xenoma through exocytosis and could be an infection source of other tissues. Demonstrated with transmission electron microscopy and fluorescent staining, the xenoma was enveloped by a monolayer membrane, and full of vesicle structures, mitochondria, and endoplasmic reticulum around parasites in development, suggesting that high level of energy and nutrients were produced to support the massive proliferation of the parasites. Multiple hypertrophic nuclei were found in one single xenoma, indicating that the cyst was probably formed by fusion of multiple muscle cells. Observed by fluorescence in situ hybridization, pathogens in the xenoma were in merongony, sporogony, and octosporogony, and mature stages. And mature spores were pushed to the center while vegetative pathogens were in the surface layer of the xenoma. The V. necatrix meront usually contained two to three nuclei, and sporont contained two nuclei and was wrapped by a thick membrane with high electron density. The V. necatrix sporogony produces two types of spores, the ordinary dikaryotic spore and unicellular octospores, the latter of which were smaller in size and packed in a sporophorous vesicle. In summary, V. necatrix xenoma is a specialized cyst likely formed by fusion of multiple muscle cells and provides high concentration of energy and nutrients with increased number of mitochondria and endoplasmic reticulum for the massive proliferation of pathogens inside.

Improved device performance of recessed-gate AlGaN/GaN HEMTs using by in-situ N2O radical treatment

2022 ◽  
Author(s):  
Xinchuang Zhang ◽  
Mei Wu ◽  
Bin Hou ◽  
Xuerui Niu ◽  
Hao Lu ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Electron Mobility Transistors ◽  
Device Performance ◽  
High Electron ◽  
Electron Mobility Transistors ◽  
Transmission Electron ◽  
Order Of Magnitude ◽  
Recessed Gate ◽  
Gate Recess

Abstract In this work, the N2O radicals in-situ treatment on gate region has been employed to improve device performance of recessed-gate AlGaN/GaN high-electron-mobility transistors (HEMTs). The samples after gate recess etching were treated by N2O radicals without physical bombardment. After in-situ treatment (IST) processing, the gate leakage currents decreased by more than one order of magnitude compared to the sample without IST. The fabricated HEMTs with the IST process show a low reverse gate current of 10-9 A/mm, high on/off current ratio of 108, and high fT×Lg of 13.44 GHz·μm. A transmission electron microscope (TEM) imaging illustrates an oxide layer with a thickness of 1.8 nm exists at the AlGaN surface. X-ray photoelectron spectroscopy (XPS) measurement shows that the content of the Al-O and Ga-O bonds elevated after IST, indicating that the Al-N and Ga-N bonds on the AlGaN surface were broken and meanwhile the Al-O and Ga-O bonds formed. The oxide formed by a chemical reaction between radicals and the surface of the AlGaN barrier layer is responsible for improved device characteristics.

Multiscale 3D Virtual Dissections of 100-Million-Year-Old Flowers Using X-Ray Synchrotron Micro- and Nanotomography

2014 ◽  
Vol 20 (1) ◽  
pp. 305-312 ◽  
Author(s):  
Jean-David Moreau ◽  
Peter Cloetens ◽  
Bernard Gomez ◽  
Véronique Daviero-Gomez ◽  
Didier Néraudeau ◽  
...  
Keyword(s):  
Phase Contrast ◽  
Three Dimensional ◽  
Multiscale Approach ◽  
X Ray ◽  
Local Tomography ◽  
Transmission Electron ◽  
Wide Range ◽  
Fossil Flowers ◽  
High Level

AbstractA multiscale approach combining phase-contrast X-ray micro- and nanotomography is applied for imaging a Cretaceous fossil inflorescence in the resolution range from 0.75 μm to 50 nm. The wide range of scale views provides three-dimensional reconstructions from the external gross morphology of the inflorescence fragment to the finest exine sculptures of in situ pollen. This approach enables most of the characteristics usually observed under light microscopy, or with low magnification under scanning and transmission electron microscopy, to be obtained nondestructively. In contrast to previous tomography studies of fossil and extant flowers that used resolutions down to the micron range, we used voxels with a 50 nm side in local tomography scans. This high level of resolution enables systematic affinities of fossil flowers to be established without breaking or slicing specimens.

New Insights on the Morphology of Nanocomposite Prepared by In Situ Emulsion Polymerization

2015 ◽  
Vol 775 ◽  
pp. 170-175
Author(s):  
José Costa de Macêdo Neto ◽  
João Evangelista Neto ◽  
Nayra Reis do Nascimento ◽  
Sheila Contant ◽  
Liliane Maria Ferrareso Lona
Keyword(s):  
Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
X Ray Diffraction ◽  
Nanocomposite Powder ◽  
Thin Sections ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Level Of Details ◽  
High Level

In order to better understand the morphology and properties of polymer nanocomposites it is necessary to conduct their characterization by Transmission Electron Microscopy (TEM). This work shows a technique through which the nanocomposite powder is mixed with a resin, and after cured, thin sections can be obtained by ultramicrotomy. Another technique presented in this work deals with the observation of clay powder in solution. In this work High Resolution Electron Microscopy (HRTEM) was used to obtain images of the nanocomposites and clay. Images with a high level of details were showed. Through the use of such techniques, it was possible to observe two types of clay morphology in polymer matrix and its distribution. The dimensions and hexagonal layers of the natural clay used as nanofiller for the nanocomposite were also observed. The X-ray Diffraction (XRD) was used to investigate the kaolinite and nanocomposite.

Growth of Crack-Free GaN on Si HEMTs with Fe-Doped GaN Using Un-Doped GaN Interlayer

2016 ◽  
Vol 858 ◽  
pp. 1194-1197
Author(s):  
Atsushi Era ◽  
Susumu Hatakenaka ◽  
Hiroyuki Okazaki ◽  
Yoshitaka Kamo ◽  
Takehiro Nishida ◽  
...  
Keyword(s):  
High Electron Mobility Transistors ◽  
Threading Dislocations ◽  
High Electron ◽  
Fe Doping ◽  
Electron Mobility Transistors ◽  
Transmission Electron ◽  
Microscope Images ◽  
Gan On Si ◽  
Reflectance Measurements

We show the influence of Fe-doping upon bowing and cracking in GaN-on-Si based high-electron-mobility transistors (HEMTs) and report how to prevent from bowing and cracking. In-situ reflectance measurements revealed that stress relaxation occurred during the growth of GaN:Fe on Al0.25Ga0.75N, resulting in the wafer bowing and cracking. In-situ measurements and transmission electron microscope images showed that the relaxation was caused by the 3D growth of GaN:Fe and the propagation of threading dislocations. To suppress the relaxation, a 100 nm-thick un-doped GaN interlayer was inserted between GaN:Fe and Al0.25Ga0.75N. As a result, a crack-free low-bow surface was obtained for GaN-on-Si HEMTs with GaN:Fe.

scholarly journals Subcellular fractionation and morphology of calf aortic smooth muscle cells: studies on whole aorta, aortic explants, and subcultures grown under

1977 ◽  
Vol 75 (1) ◽  
pp. 166-184 ◽  
Author(s):  
S Fowler ◽  
H Shio ◽  
H Wolinsky
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Plasma Membranes ◽  
Muscle Cells ◽  
Cell Fractionation ◽  
Aortic Smooth Muscle Cells ◽  
Aortic Smooth Muscle

A comparative biochemical and morphological study was made of calf aortic smooth muscle cells found in situ and grown in vitro under various conditions. Striking alterations in enzyme contents, physical properties, and morphological appearances of lysosomes, endoplasmic reticulum, plasma membranes and, to a lesser extent, mitochondria were observed upon culturing of calf aortic smooth muscle cells. These changes first appeared in cells growing out of tissue explants. They developed further upon subculturing of the cells and depended greatly on the culture conditions used. The alterations included increases in specific activities of some 5- to 25-fold of four acid hydrolases, an average ninefold increase in 5' -nucleotidase, sevenfold increase in cytochrome oxidase, and fourfold increase in neutral α-glucosidase in subcultured smooth muscle cells compared to aortic cells in situ. Cell fractionation studies showed significant shifts in the equilibrium densities of plasma membranes, microsomes, and lysosomes, but not of mitochondria, in smooth muscle cells growing out from explants and in subcultured cells, compared to cells isolated from intact aortas. Although the cells grown in vitro exhibited typical phenotypic features of smooth muscle cells such as abundant myofilaments and surface vesicles, alterations in the morphological appearance of the endoplasmic reticulum, Golgi apparatus, and, especially, lysosomes were observed. These results demonstrate significant differences in specific cellular characteristics and functions of aortic smooth muscle cells grown in vitro compared to aortic cells in situ.

scholarly journals Comparision on the Low-Temperature NH3-SCR Performance of γ-Fe2O3 Catalysts Prepared by Two Different Methods

Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1018
Author(s):  
Naveed Husnain ◽  
Enlu Wang ◽  
Shagufta Fareed ◽  
Muhammad Tuoqeer Anwar
Keyword(s):  
Photoelectron Spectroscopy ◽  
Catalytic Reduction ◽  
Acid Sites ◽  
High Concentration ◽  
X Ray ◽  
Nh3 Scr ◽  
Transmission Electron ◽  
Temperature Programmed ◽  
Diffuse Reflectance Infrared

Maghemite (γ-Fe2O3) catalysts were prepared by two different methods, and their activities and selectivities for selective catalytic reduction of NO with NH3 were investigated. The methods of X-ray powder diffraction (XRD), Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H2-TPR), ammonia temperature-programmed desorption (NH3-TPD), transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS), and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) were used to characterize the catalysts. The resulted demonstrated that the γ-Fe2O3 nanoparticles prepared by the facile method (γ-Fe2O3–FM) not only exhibited better NH3-SCR activity and selectivity than the catalyst prepared by the coprecipitation method but also showed improved SO2 tolerance. This superior NH3-SCR performance was credited to the existence of the larger surface area, better pore structure, a high concentration of lattice oxygen and surface-adsorbed oxygen, good reducibility, a lot of acid sites, lower activation energy, adsorption of the reactants, and the existence of unstable nitrates on the surface of the γ-Fe2O3–FM.

A comparison of radiation effects in crystalline ABO4-type phosphates and silicates

2000 ◽  
Vol 64 (2) ◽  
pp. 185-194 ◽  
Author(s):  
A. Meldrum ◽  
L. A. Boatner ◽  
R. C. Ewing
Keyword(s):  
Damage Accumulation ◽  
Radiation Effects ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Chemical Compositions ◽  
Transmission Electron ◽  
Host Materials ◽  
High Level Nuclear Waste ◽  
High Level

AbstractThe effects of ion irradiation in the ABO4-type compounds were compared by performing experiments on four materials that include the most common crystal structures (monazite vs. zircon) and chemical compositions (phosphates vs. silicates) for these phases. Pure synthetic single crystals of ZrSiO4, monoclinic ThSiO4, LaPO4 and ScPO4 were irradiated using 800 keV Kr+ ions. Radiation damage accumulation was monitored as a function of temperature in situ in a transmission electron microscope. The activation energies for recrystallization during irradiation were calculated to be 3.1–3.3 eV for the orthosilicates but only 1.0–1.5 eV for the isostructural orthophosphates. For the ion-beam-irradiated samples, the critical temperature, above which the recrystallization processes are faster than damage accumulation and amorphization cannot be induced, is >700°C for ZrSiO4 but it is only 35°C for LaPO4. At temperatures above 600°C, zircon decomposed during irradiation into its component oxides (i.e. crystalline ZrO2 plus amorphous SiO2). The data are evaluated with respect to the proposed use of the orthophosphates and orthosilicates as host materials for the stabilization and disposal of high-level nuclear waste. The results show that zircon with 10 wt.% Pu would have to be maintained at temperatures in excess of 300°C in order to prevent it from becoming completely amorphous. In contrast, a similar analysis for the orthophosphates implies that monazite-based waste forms would not become amorphous or undergo a phase decomposition.

scholarly journals Transmission Electron Microscopy Study In-Situ of Radiation-Induced Defects in Copper at Elevated Temperatures

1996 ◽  
Vol 439 ◽  
Author(s):  
T. L. Daulton ◽  
M. A. Kirk ◽  
L. E. Rehn
Keyword(s):  
Point Defects ◽  
Elevated Temperatures ◽  
Defect Density ◽  
Microscopy Study ◽  
High Energy ◽  
Dislocation Loops ◽  
Contrast Imaging ◽  
High Concentration ◽  
Transmission Electron

AbstractNeutrons and high-energy ions incident upon a solid can initiate a displacement collision cascade of lattice atoms resulting in localized regions within the solid containing a high concentration of interstitial and vacancy point defects. These point defects can collapse into various types of dislocation loops and stacking fault tetrahedra (SFT) large enough that their lattice strain fields are visible under diffraction-contrast imaging using a Transmission Electron Microscope (TEM). The basic mechanisms driving the collapse of point defects produced in collision cascades is investigated in situ with TEM for fcc-Cu irradiated with heavy (100 keV Kr) ions at elevated temperature. The isothermal stability of these clusters is also examined in situ.Areal defect yields were observed to decrease abruptly for temperatures greater than 300°C. This decrease in defect yield is attributed to a proportional decrease in the probability of collapse of point defects into clusters. The evolution of the defect density under isothermal conditions appears to be influenced by three different rate processes active in the decline of the total defect density. These rate constants can be attributed to differences in the stability of various types of defect clusters and to different loss mechanisms. Based upon observed stabilities, estimations for the average binding enthalpies of vacancies to SFT are calculated for copper.

scholarly journals Atomistic insights into the nucleation and growth of platinum on palladium nanocrystals

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wenpei Gao ◽  
Ahmed O. Elnabawy ◽  
Zachary D. Hood ◽  
Yifeng Shi ◽  
Xue Wang ◽  
...  
Keyword(s):  
Diffusion Path ◽  
Nucleation Site ◽  
Nucleation And Growth ◽  
First Principles Calculations ◽  
High Concentration ◽  
Synthesis Parameters ◽  
Transmission Electron ◽  
Liquid Cell ◽  
Shed Light

AbstractDespite the large number of reports on colloidal nanocrystals, very little is known about the mechanistic details in terms of nucleation and growth at the atomistic level. Taking bimetallic core-shell nanocrystals as an example, here we integrate in situ liquid-cell transmission electron microscopy with first-principles calculations to shed light on the atomistic details involved in the nucleation and growth of Pt on Pd cubic seeds. We elucidate the roles played by key synthesis parameters, including capping agent and precursor concentration, in controlling the nucleation site, diffusion path, and growth pattern of the Pt atoms. When the faces of a cubic seed are capped by Br−, Pt atoms preferentially nucleate from corners and then diffuse to edges and faces for the creation of a uniform shell. The diffusion does not occur until the Pt deposited at the corner has reached a threshold thickness. At a high concentration of the precursor, self-nucleation takes place and the Pt clusters then randomly attach to the surface of a seed for the formation of a non-uniform shell. These atomistic insights offer a general guideline for the rational synthesis of nanocrystals with diverse compositions, structures, shapes, and related properties.

Sign in / Sign up

Export Citation Format

Share Document