scholarly journals Exposure to hypoxia injures tracheal epithelium (ultrastructural study)

2012 ◽  
Vol 47 (No. 9) ◽  
pp. 270-276 ◽  
Author(s):  
V. Konrádová ◽  
J. Uhlík ◽  
L. Vajner ◽  
J. Herget ◽  
J. Adášková
Keyword(s):  
High Temperature ◽  
Ultrastructural Study ◽  
Goblet Cells ◽  
Normobaric Hypoxia ◽  
Tracheal Epithelium ◽  
Second Phase ◽  
Ciliated Cells ◽  
Pathological Alteration ◽  
Increased Temperature ◽  
Common Response

The ultrastructure of the tracheal epithelium in rabbits exposed for 96 hours to normobaric hypoxia was studied. In rabbits placed for 96 hours in environment with increased temperature and humidity, the first phase of common response of goblet cells to injury, represented mostly by degeneration of the exhausted cells, was revealed. The decrease in O<sub>2</sub>concentration highly accelerated the reaction of the goblet cells. Due to the influence of high temperature, humidity and normobaric hypoxia, the second phase of the goblet cells&rsquo; reaction, massive differentiation of new secretory elements accompanied with intraepithelial mucous glands&rsquo; development, was recorded. In the ciliated cells, only mild signs of pathological alteration of deeper portions of their cytoplasm were noticed. In the area of the ciliary border, significant decrease in the number of kinocilia/&mu;m2, increase in percentage of altered cilia and morphological signs of impairment of the vital self-cleaning ability were recorded.

scholarly journals Mild hyperoxia induces moderate pathological alteration in airway epithelium (ultrastructural study)

2012 ◽  
Vol 48 (No. 11) ◽  
pp. 313-320
Author(s):  
V. Koonradova ◽  
J. Uhlik ◽  
L. Vajner ◽  
J. Herget ◽  
J. Adaskova
Keyword(s):  
Ultrastructural Study ◽  
Airway Epithelium ◽  
Goblet Cells ◽  
Point Of View ◽  
Tracheal Epithelium ◽  
Ciliated Cells ◽  
Normobaric Hyperoxia ◽  
Pathological Alteration ◽  
The Mean ◽  
Self Cleaning

The ultrastructure of the tracheal epithelium in rabbits exposed for 96 hours to 35&ndash;37% O2 was studied in our experiments. Due to the influence of mild normobaric hyperoxia, massive differentiation of new secretory elements was initiated and resulted in apparent changes in goblet cells distribution. 60 &plusmn; 4% of goblet cells took part in the formation of voluminous intraepithelial mucous glands. Ciliated cells were less damaged than the goblet ones. Tiny signs of pathological alteration of deeper portions of their cytoplasm and apical blebbing accompanied with destruction of some kinocilia were encountered. The ciliary border was slightly impaired. Mild, but significant decrease in the mean number of kinocilia/&mu;m2 went along with significant increase in percentage of altered cilia. Among the altered kinocilia, the slightly altered pathological cilia with local swellings of the ciliary membranes or with tiny vacuoles situated in their shafts were the most numerous. Hyperoxia did not influence the process of ciliogenesis in the ciliated cells. As morphological signs of impairment of the vital self-cleaning ability of the airway epithelium, layers of inspissated mucus were encountered in the area of the ciliary border. From morphological point of view, mild hyperoxia caused moderate damage to the airway epithelium.

Localization of Peroxidase Activity in Tracheal Epithelium

1980 ◽  
Vol 89 (3) ◽  
pp. 241-248 ◽  
Author(s):  
Kensuke Watanabe
Keyword(s):  
Peroxidase Activity ◽  
Secretory Granules ◽  
Goblet Cells ◽  
Tracheal Ring ◽  
Tracheal Epithelium ◽  
Basal Cells ◽  
Ciliated Cells ◽  
Cytochemical Demonstration ◽  
Apical Vesicles ◽  
Intermediate Cells

The activity of endogenous peroxidase was demonstrated in light ciliated cells, mature goblet cells, and nonciliated serous cells, but not in basal cells, intermediate cells, dark ciliated cells or immature goblet cells of the upper tracheal epithelium of rats, using the diaminobenzidine method for cytochemical demonstration of peroxidase activity. The peroxidase activity was the most intense in the epithelium of the first tracheal ring and gradually diminished at lower tracheal levels, becoming extremely faint in the vicinity of the middle of the trachea. The activity was localized in cisternae of rough-surfaced endoplasmic reticulum (r-ER) including the nuclear envelope, some vesicles and saccules of the Golgi complex, secretory granules, and small apical vesicles. It is believed that the basal cells were transformed into the intermediate cells, and some of the intermediate cells were turned into the ciliated cells, while other intermediate cells were differentiated into the goblet cells. The dark ciliated cells proved to be the immature ciliated cells immediately after the transformation from the intermediate cells. In these cells, peroxidase is not yet produced.

TEM Studies of Grain Boundary Films in Si3N4 Ceramics

1991 ◽  
Vol 49 ◽  
pp. 930-931
Author(s):  
H.-J. Kleebe ◽  
J.S. Vetrano ◽  
J. Bruley ◽  
M. Rühle
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Hot Isostatic Pressing ◽  
Amorphous Film ◽  
Liquid Phase Sintering ◽  
Second Phase ◽  
High Temperature Mechanical Properties ◽  
Triple Points ◽  
Boundary Films

It is expected that silicon nitride based ceramics will be used as high-temperature structural components. Though much progress has been made in both processing techniques and microstructural control, the mechanical properties required have not yet been achieved. It is thought that the high-temperature mechanical properties of Si3N4 are limited largely by the secondary glassy phases present at triple points. These are due to various oxide additives used to promote liquid-phase sintering. Therefore, many attempts have been performed to crystallize these second phase glassy pockets in order to improve high temperature properties. In addition to the glassy or crystallized second phases at triple points a thin amorphous film exists at two-grain junctions. This thin film is found even in silicon nitride formed by hot isostatic pressing (HIPing) without additives. It has been proposed by Clarke that an amorphous film can exist at two-grain junctions with an equilibrium thickness.

Microstructural characterization of a rapidly solidified Al-Fe-V-Si alloy for elevated temperature applications

1988 ◽  
Vol 46 ◽  
pp. 550-551
Author(s):  
R. E. Franck ◽  
J. A. Hawk ◽  
G. J. Shiflet
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Grain Growth ◽  
Volume Fraction ◽  
Microstructural Characterization ◽  
Second Phase ◽  
Microstructural Stability ◽  
Elevated Temperature Strength ◽  
Temperature Applications

Rapid solidification processing (RSP) is one method of producing high strength aluminum alloys for elevated temperature applications. Allied-Signal, Inc. has produced an Al-12.4 Fe-1.2 V-2.3 Si (composition in wt pct) alloy which possesses good microstructural stability up to 425°C. This alloy contains a high volume fraction (37 v/o) of fine nearly spherical, α-Al12(Fe, V)3Si dispersoids. The improved elevated temperature strength and stability of this alloy is due to the slower dispersoid coarsening rate of the silicide particles. Additionally, the high v/o of second phase particles should inhibit recrystallization and grain growth, and thus reduce any loss in strength due to long term, high temperature annealing.The focus of this research is to investigate microstructural changes induced by long term, high temperature static annealing heat-treatments. Annealing treatments for up to 1000 hours were carried out on this alloy at 500°C, 550°C and 600°C. Particle coarsening and/or recrystallization and grain growth would be accelerated in these temperature regimes.

Precipitate coarsening during hot-compression testing of NiAl + 2 at.% Nb

1986 ◽  
Vol 44 ◽  
pp. 598-599
Author(s):  
W. M. Sherman ◽  
K. M. Vedula
Keyword(s):  
High Temperature ◽  
Flow Stress ◽  
Weight Ratio ◽  
Constant Strain Rate ◽  
Hot Compression ◽  
Compression Testing ◽  
Second Phase ◽  
Precipitate Coarsening ◽  
High Temperature Mechanical Properties ◽  
Ordered Intermetallic

The strength to weight ratio and oxidation resistance of NiAl make this ordered intermetallic, with some modifications, an attractive candidate to compete with many superalloys for high temperature applications. Recent studies have shown that the inherent brittleness of many polycrystalline intermetallics can be overcome by micro and macroalloying. It has also been found that the high temperature mechanical properties of NiAl can be enhanced through the addition of Nb by powder metallurgical techniques forming a dispersed second phase through interdiffusion in a polycrystalline matrix. A drop in the flow stress is observed however in a NiAl-2 at.% Nb alloy after 0.2 % strain during constant strain rate hot compression testing at 1025°C. The object of this investigation was to identify the second phase and to determine the cause of the flow stress drop.

Nanovaccine: A hope to triumph the battle against novel Coronavirus disease 2019 (COVID-19)

2021 ◽  
Vol 15 ◽  
Author(s):  
Anurag Singh ◽  
Anand Maurya ◽  
Gaurav Mishra ◽  
Rajendra Awasthi ◽  
Kamal Dua ◽  
...  
Keyword(s):  
Subunit Vaccine ◽  
Goblet Cells ◽  
Spike Protein ◽  
Effective Vaccine ◽  
The Novel ◽  
Infection Site ◽  
Peptide Vaccines ◽  
Ciliated Cells ◽  
Novel Coronavirus ◽  
Major Target

Background: The novel coronavirus 2019 (COVID-19) infection has caused the global emergence of coronavirus in humans during the last 12 months. Till May 11, 2021, the confirmed global COVID-19 cases and deaths reached 158551526 and 3296855, respectively. Methods: Goblet cells and ciliated cells in the nose act as the initial infection site of SARS-CoV-2. Thus, mucus immunity is important to protect from infection. The outburst of SARS-CoV-2 infection can be halted only when an effective vaccine will be developed. Results: Globally, over 100 different vaccines are under investigation, including DNA vaccines, RNA vaccines, inactivated virus vaccines, adenovirus-based vaccines, recombinant/ subunit protein vaccines, peptide vaccines, and virus-like particles etc. Inactivated virus vaccines and mRNA, and adenovirus-based vaccines have moved fast into clinical trials. Conclusion: : Vaccines containing spike protein of SARS-CoV as subunit could effectively prevent binding of coronavirus to the host cell and membrane fusion. Thus, spike protein can be used as a major target for subunit vaccine preparation.

Features of Developing Ferret Tracheal Epithelium: Ultrastructural Observations of in Vivo and in Vitro Differentiation of Ciliated Cells

1987 ◽  
Vol 13 (2) ◽  
pp. 223-240 ◽  
Author(s):  
Linda N. Curtis ◽  
Johnny L. Carson ◽  
Albert M. Collier ◽  
Todd M. Gambling ◽  
S. S. Hu ◽  
...  
Keyword(s):  
Tracheal Epithelium ◽  
Ciliated Cells ◽  
In Vitro Differentiation

scholarly journals Development of Creep-Resistant, Alumina-Forming Ferrous Alloys for High-Temperature Structural Use

2018 ◽  
Author(s):  
Y. Yamamoto ◽  
M. P. Brady ◽  
G. Muralidharan ◽  
B. A. Pint ◽  
P. J. Maziasz ◽  
...  
Keyword(s):  
High Temperature ◽  
Elevated Temperatures ◽  
Extreme Environments ◽  
Alloy Design ◽  
Austenitic Steels ◽  
Strength Development ◽  
Second Phase ◽  
Ferrous Alloys ◽  
Steel Alloys ◽  
Structural Applications

This paper overviews recent advances in developing novel alloy design concepts of creep-resistant, alumina-forming Fe-base alloys, including both ferritic and austenitic steels, for high-temperature structural applications in fossil-fired power generation systems. Protective, external alumina-scales offer improved oxidation resistance compared to chromia-scales in steam-containing environments at elevated temperatures. Alloy design utilizes computational thermodynamic tools with compositional guidelines based on experimental results accumulated in the last decade, along with design and control of the second-phase precipitates to maximize high-temperature strengths. The alloys developed to date, including ferritic (Fe-Cr-Al-Nb-W base) and austenitic (Fe-Cr-Ni-Al-Nb base) alloys, successfully incorporated the balanced properties of steam/water vapor-oxidation and/or ash-corrosion resistance and improved creep strength. Development of cast alumina-forming austenitic (AFA) stainless steel alloys is also in progress with successful improvement of higher temperature capability targeting up to ∼1100°C. Current alloy design approach and developmental efforts with guidance of computational tools were found to be beneficial for further development of the new heat resistant steel alloys for various extreme environments.

scholarly journals Microstructure and Tensile Properties of Graphene-Oxide-Reinforced High-Temperature Titanium-Alloy-Matrix Composites

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3358 ◽  
Author(s):  
Hang Chen ◽  
Guangbao Mi ◽  
Peijie Li ◽  
Xu Huang ◽  
Chunxiao Cao
Keyword(s):  
Tensile Strength ◽  
Titanium Alloy ◽  
Graphene Oxide ◽  
High Temperature ◽  
Yield Strength ◽  
Room Temperature ◽  
Second Phase ◽  
Matrix Composites ◽  
Alloy Matrix ◽  
The Matrix

In this study, graphene-oxide (GO)-reinforced Ti–Al–Sn–Zr–Mo–Nb–Si high-temperature titanium-alloy-matrix composites were fabricated by powder metallurgy. The mixed powders with well-dispersed GO sheets were obtained by temperature-controlled solution mixing, in which GO sheets adsorb on the surface of titanium alloy particles. Vacuum deoxygenating was applied to remove the oxygen-containing groups in GO, in order to reduce the introduction of oxygen. The compact composites with refined equiaxed and lamellar α phase structures were prepared by hot isostatic pressing (HIP). The results show that in-situ TiC layers form on the surface of GO and GO promotes the precipitation of hexagonal (TiZr)6Si3 particles. The composites exhibit significant improvement in strength and microhardness. The room-temperature tensile strength, yield strength and microhardness of the composite added with 0.3 wt% GO are 9%, 15% and 27% higher than the matrix titanium alloy without GO, respectively, and the tensile strength and yield strength at 600 °C are 3% and 21% higher than the matrix alloy. The quantitative analysis indicates that the main strengthening mechanisms are load transfer strengthening, grain refinement and (TiZr)6Si3 second phase strengthening, which accounted for 48%, 30% and 16% of the improvement of room-temperature yield strength, respectively.

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