scholarly journals Structure of a hinge joint with textured sliding surfaces in terrestrial isopods (Crustacea: Isopoda: Oniscidea)

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Miloš Vittori
Keyword(s):  
Electron Microscopy ◽  
High Speed ◽  
Small Particles ◽  
Porcellio Scaber ◽  
Terrestrial Isopods ◽  
Sliding Surfaces ◽  
Terrestrial Arthropods ◽  
Video Recordings ◽  
Transmission Electron ◽  
Successful Group

Abstract Background The study of joints in terrestrial arthropods can provide insights into the evolutionary optimization of contacting surfaces that slide without lubrication. This work reports on the structure of the joint between the propodus and the dactylus in terrestrial isopods, the most successful group of crustaceans on land, focusing on the woodlouse Porcellio scaber. Methods The joints were studied using fluorescence microscopy, 3D reconstruction, scanning electron microscopy and transmission electron microscopy. The obtained results were functionally interpreted using high-speed video recordings by analyzing the use of the joint during locomotion. Results In the joint, which allows the dactylus to move in a single plain, a semicircular process on the propodus fits into a groove on the dactylus and guides its movement. The sliding surfaces of the propodal process are textured in the form of parallel epicuticular ridges a few hundred nanometers thick. This texturing is selective: while the less heavily loaded surfaces are textured, the surfaces that support the isopod during standing and walking are smooth. In contrast, the groove on the dactylus is completely smooth. We found a similar surface texture in several other species of terrestrial isopods and one aquatic isopod. Conclusions The selective texturing of the joint may reduce wear by eliminating small particles. This effect of the ridges was confirmed using electron microscopy. The absence of ridges on heavily loaded surfaces may enhance the dissipation of forces in these regions.

Microtexture of shock reaction products of niobium and silica mixtures

1999 ◽  
Vol 14 (7) ◽  
pp. 3169-3174 ◽  
Author(s):  
Reiko Murao ◽  
Masae Kikuchi ◽  
Kiyoto Fukuoka ◽  
Eiji Aoyagi ◽  
Toshiyuki Atou ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Shock Compression ◽  
Pressure Range ◽  
Reaction Products ◽  
Small Particles ◽  
Powder Mixtures ◽  
X Ray ◽  
Transmission Electron

Shock compression experiments on powder mixtures of niobium metal and quartz were conducted for the pressure range of 30–40 GPa by a 25-mm single-stage propellant gun. Chemical reaction occurred above 35 GPa, and products were found to be mainly so-called “Cu3Au-type” Nb3Si, which contained a small amount of oxygen. Microtextures of the specimen were examined by scanning and transmission electron microscopy. A field-emission transmission electron microscope was used for energy-dispersive x-ray analysis of microtextures in small particles found in the SiO2 matrix, and various species with different Nb/Si ratio and oxygen content were shown to be produced through the nonequilibrium process of shock compression.

scholarly journals “Candidatus Bacilloplasma,” a Novel Lineage of Mollicutes Associated with the Hindgut Wall of the Terrestrial Isopod Porcellio scaber (Crustacea: Isopoda)

2007 ◽  
Vol 73 (17) ◽  
pp. 5566-5573 ◽  
Author(s):  
Rok Kostanjšek ◽  
Jasna Štrus ◽  
Gorazd Avguštin
Keyword(s):  
Electron Microscopy ◽  
Sequence Similarity ◽  
Mycoplasma Hominis ◽  
Sister Group ◽  
Phylogenetic Position ◽  
Rrna Gene ◽  
Porcellio Scaber ◽  
Terrestrial Isopod ◽  
Transmission Electron ◽  
A Cell

ABSTRACT Pointed, rod-shaped bacteria colonizing the cuticular surface of the hindgut of the terrestrial isopod crustacean Porcellio scaber (Crustacea: Isopoda) were investigated by comparative 16S rRNA gene sequence analysis and electron microscopy. The results of phylogenetic analysis, and the absence of a cell wall, affiliated these bacteria with the class Mollicutes, within which they represent a novel and deeply branched lineage, sharing less than 82.6% sequence similarity to known Mollicutes. The lineage has been positioned as a sister group to the clade comprising the Spiroplasma group, the Mycoplasma pneumoniae group, and the Mycoplasma hominis group. The specific signature sequence was identified and used as a probe in in situ hybridization, which confirmed that the retrieved sequences originate from the attached rod-shaped bacteria from the hindgut of P. scaber and made it possible to detect these bacteria in their natural environment. Scanning and transmission electron microscopy revealed a spherically shaped structure at the tapered end of the rod-shaped bacteria, enabling their specific and exclusive attachment to the tip of the cuticular spines on the inner surface of the gut. Specific adaptation to the gut environment, as well as phylogenetic positioning, indicate the long-term association and probable coevolution of the bacteria and the host. Taking into account their pointed, rod-shaped morphology and their phylogenetic position, the name “Candidatus Bacilloplasma” has been proposed for this new lineage of bacteria specifically associated with the gut surface of P. scaber.

scholarly journals Compressed Sensing of Scanning Transmission Electron Microscopy (STEM) With Nonrectangular Scans

2018 ◽  
Vol 24 (6) ◽  
pp. 623-633 ◽  
Author(s):  
Xin Li ◽  
Ondrej Dyck ◽  
Sergei V. Kalinin ◽  
Stephen Jesse
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Real Time ◽  
Scanning Transmission Electron Microscopy ◽  
High Speed ◽  
Dynamic Range ◽  
Extended Defects ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

AbstractScanning transmission electron microscopy (STEM) has become the main stay for materials characterization on atomic level, with applications ranging from visualization of localized and extended defects to mapping order parameter fields. In recent years, attention has focused on the potential of STEM to explore beam induced chemical processes and especially manipulating atomic motion, enabling atom-by-atom fabrication. These applications, as well as traditional imaging of beam sensitive materials, necessitate increasing the dynamic range of STEM in imaging and manipulation modes, and increasing the absolute scanning speed which can be achieved by combining sparse sensing methods with nonrectangular scanning trajectories. Here we have developed a general method for real-time reconstruction of sparsely sampled images from high-speed, noninvasive and diverse scanning pathways, including spiral scan and Lissajous scan. This approach is demonstrated on both the synthetic data and experimental STEM data on the beam sensitive material graphene. This work opens the door for comprehensive investigation and optimal design of dose efficient scanning strategies and real-time adaptive inference and control of e-beam induced atomic fabrication.

Growth of TiN/AlN Superlattice by Pulsed Laser Deposition

2002 ◽  
Vol 750 ◽  
Author(s):  
H. Wang ◽  
A. Gupta ◽  
Ashutosh Tiwari ◽  
X. Zhang ◽  
J. Narayan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Pulsed Laser Deposition ◽  
High Speed ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Internal Stresses ◽  
Layer By Layer ◽  
Special Configuration ◽  
Transmission Electron

ABSTRACTTiN-AlN binary-components have attracted a lot of interests in coatings of high speed cutting tools, due to their higher oxidation resistance, higher hardness, lower internal stresses and better adhesion. Especially, nanometer-scale multilayer structures of AlN/TiN show superior structural and mechanical properties due to their tremendous interface area and become one of the promising candidates for superhard coatings. Here we present a novel method to grow highly aligned TiN/AlN superlattice by pulsed laser deposition. In this method TiN and AlN targets are arranged in a special configuration that they can be ablated in sequence, giving alternate layer by layer growth of TiN(1nm)/AlN(4nm). X-ray diffraction and transmission electron microscopy (TEM) analysis showed the structure to be cubic for both TiN and AlN in the nanoscale multilayers. Microstructure and uniformity for the superlattice structure were studied by TEM and Scanning transmission electron microscopy with Z-contrast (STEM). Nanoindentation results indicated a higher hardness for this new structure than pure AlN and rule-of-mixtures value. Four point probe electrical resistivity measurements showed overall insulating behavior.

Usefulness of high-speed digital imaging (HSDI) in the diagnosis of oedematous – hypertrophic changes of the larynx in people using voice occupationally

2017 ◽  
Vol 71 (4) ◽  
pp. 19-25 ◽  
Author(s):  
Bożena Kosztyła-Hojna ◽  
Diana Moskal ◽  
Anna Kuryliszyn-Moskal ◽  
Anna Andrzejewska ◽  
Anna Łobaczuk-Sitnik ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Digital Imaging ◽  
Vocal Fold ◽  
High Speed ◽  
Vocal Folds ◽  
Intercellular Spaces ◽  
Vacuolar Degeneration ◽  
Transmission Electron ◽  
Tem Method ◽  
Hypertrophic Changes

Introduction. The aim of the study is the evaluation of the usefulness of High-Speed Digital Imaging (HSDI) in the diagnosis of organic dysphonia in a form of oedematous-hypertrophic changes of vocal fold mucosa, morphologically confirmed by Transmission Electron Microscopy (TEM) method in patients working with voice occupationally. Material and methods. The group consisted of 30 patients working with voice occupationally with oedematous-hypertrophic changes of vocal fold mucosa. Parameters of vocal folds vibrations were evaluated using HSDI technique with a digital HS camera, HRES Endocam Richard Wolf GmbH. The image of vocal folds was recorded with a rate of 4000 frames per second. Postoperative material of the larynx was prepared in a routine way and observed in transmission electron microscope OPTON 900–PC. Results. HSDI technique allows to assess the real vibrations of vocal folds and determine many parameters. The results of TEM in the postoperative material showed destruction of epithelial cells with severe vacuolar degeneration, the enlargement of intercellular spaces and a large number of blood vessels in the stroma, which indicates the presence of oedematous-hypertrophic changes of the larynx. Discussion. The ultrastructural assessment confirm the particular usefulness of HSDI method in the diagnosis of organic dysphonia in a form of oedematous-hypertrophic changes. Key words: High-Speed Digital Imaging, oedematous-hypertrophic changes, vocal fold mucosa, larynx

Unusual Rapidity of Electron Beam Transient Tempering

1986 ◽  
Vol 80 ◽  
Author(s):  
Anjum Tauqir ◽  
Peter R. Strutt
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Thermal Treatment ◽  
Rapid Solidification ◽  
High Speed ◽  
Defect Cluster ◽  
High Concentration ◽  
Transmission Electron ◽  
Nucleation Sites

AbstractElectron beam rapid solidification of molybdenum-base high speed steels results in quenched-in metastable phases containing a high concentration of alloying elements. Thermal reprocessing of such material by momentary interaction with the electron beam results in decomposition of martensite at a rate ≈ 100 times faster than that occurring during conventional thermal treatment. It is postulated that this arises from a high concentration of 'defect cluster nucleation sites' during the rapid up-quenching. The product of short thermal treatment is a dispersion of 2–5 nm very fine precipitates identified using transmission electron microscopy as MC type carbides.

Studies of Ultra-High Speed Silicon Crystal Growth From The Melt By Use of Conventional and High Resolution Transmission Electron Microscopy

1985 ◽  
Vol 43 ◽  
pp. 22-25
Author(s):  
A. G. Cullis
Keyword(s):  
Electron Microscopy ◽  
Crystal Growth ◽  
High Resolution ◽  
High Speed ◽  
Solid Phase ◽  
Silicon Crystal ◽  
Amorphous Solid ◽  
Orientation Dependence ◽  
Transmission Electron ◽  
Resolution Imaging

Fast melting and solidification of semiconductors by use of Q-switched laser irradiation techniques has provided, during the last few years, a large amount of information on novel high speed crystal growth processes. Under the highest quench rate conditions, the motion of the final solidification interface can be so rapid (many metres per second) that atomic ordering processes are overwhelmed and either defective crystal or even the amorphous solid phase is formed. Most work in this area has been carried out on elemental Si and electron microscopy of solidification structures has played an essential analytical role through both conventional and high resolution imaging studies. The present paper will outline recent progress which has been made in understanding the crystallographic orientation dependence of high-speed growth phenomena.

The identification of single-domain titanomagnetite particles by means of transmission electron microscopy

1979 ◽  
Vol 16 (2) ◽  
pp. 375-379 ◽  
Author(s):  
P. P. K. Smith
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Remanent Magnetization ◽  
Magnetic Domain ◽  
Natural Remanent Magnetization ◽  
Small Particles ◽  
Dispersed Particles ◽  
Transmission Electron ◽  
Mid Atlantic Ridge ◽  
Means Of Transmission

A basalt sample dredged from the axis of the Mid-Atlantic Ridge has been ion-thinned and examined by transmission electron microscopy. Finely dispersed particles as small as 0.04 μm in diameter, occurring in amorphous patches of the rock, have been identified as titanomagnetite by means of electron diffraction and microanalysis. These small particles have dimensions appropriate to single magnetic domain behaviour, and are considered to be largely responsible for the strong and very stable natural remanent magnetization of this rock.

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