scholarly journals Lacandonia granules are present in the cell nucleus of Welwitschia mirabilis

2018 ◽  
Vol 96 (4) ◽  
pp. 678
Author(s):  
Lourdes-Teresa Agredano-Moreno ◽  
María De Lourdes Segura-Valdez ◽  
Jaime Jiménez-Ramírez ◽  
Luis-Felipe Jiménez-García
Keyword(s):  
Cell Nucleus ◽  
Chironomus Tentans ◽  
Balbiani Ring ◽  
Cell Nuclei ◽  
Thin Sections ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Welwitschia Mirabilis ◽  
Species Study

<p><strong>Background:</strong> <em>Lacandonia</em> granules are extranucleolar ribonucleoprotein (RNPs) particles, 32 nanometers in diameter that were first described in the nucleus of <em>Lacandonia schismatica</em>. Cytochemical and immunocytochemical studies suggest that these particles are equivalent to perichromatin and Balbiani ring granules described in mammals and salivary glands cells of the insect <em>Chironomus tentans, </em>respectively. <em>Lacandonia</em> granules are also present in the related <em>Triuris</em> <em>brevystilis</em>,<em> </em>and they were later described in the gymnosperm <em>Ginkgo biloba</em>. These findings suggest that <em>Lacandonia </em>granules have a wider distribution in the plant kingdom. </p><p><strong>Species study:</strong> The plant <em>Welwitschia mirabilis, </em>a gymnosperm of the order Gnetales.</p><p><strong>Hyphotesis: </strong><em>Lacandonia</em> granules are present in the cell nucleus of <em>W. mirabilis</em>.<strong> </strong></p><p><strong>Methods:</strong> Plants were cultivated<strong> </strong>in a germination chamber and samples of leaves were processed for transmission electron microscopy. Thin sections were stained with the EDTA technique preferential for ribonucleoproteins and osmium amine specific for DNA and observed with a microscopy.</p><p><strong>Results:</strong> Light, electronic and atomic force microscopy revealed that cell nuclei of <em>W. mirabilis</em> display a reticulated arrangement of chromatin. Moreover, granules of 32.17 ± 1.7 nm in diameter were observed among strands of reticulated chromatin.</p><p><strong>Conclusions:</strong> Our results indicate that <em>Lacandonia</em> granules are present in the nuclei of the gnetal <em>W. </em> <em>mirabilis.</em></p>

scholarly journals The synovial surface of the articular cartilage

2020 ◽  
Vol 64 (3) ◽  
Author(s):  
Petra Rita Basso ◽  
Elena Carava' ◽  
Marina Protasoni ◽  
Marcella Reguzzoni ◽  
Mario Raspanti
Keyword(s):  
Electron Microscopy ◽  
Articular Cartilage ◽  
Articular Surface ◽  
Collagen Fibrils ◽  
Huge Amount ◽  
Thin Sections ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
The Subject

The articular cartilage has been the subject of a huge amount of research carried out with a wide array of different techniques. Most of the existing morphological and ultrastructural data on the this tissue, however, were obtained either by light microscopy or by transmission electron microscopy. Both techniques rely on thin sections and neither allows a direct, face-on visualization of the free cartilage surface (synovial surface), which is the only portion subject to frictional as well as compressive forces. In the present research, high resolution visualization by scanning electron microscopy and by atomic force microscopy revealed that the collagen fibrils of the articular surface are exclusively represented by thin, uniform, parallel fibrils evocative of the heterotypic type IX-type II fibrils reported by other authors, immersed in an abundant matrix of glycoconjugates, in part regularly arranged in phase with the D-period of collagen. Electrophoresis of fluorophore-labeled saccharides confirmed that the superficial and the deeper layers are quite different in their glycoconjugate content as well, the deeper ones containing more sulfated, more acidic small proteoglycans bound to thicker, more heterogenous collagen fibrils. The differences found between the synovial surface and the deeper layers are consistent with the different mechanical stresses they must withstand.

Rapid Preparation of a Polymer Fiber and a Free-Standing Polymer Film for Cross-Sectional Microtomy

2003 ◽  
Vol 11 (4) ◽  
pp. 36-39 ◽  
Author(s):  
Andreas Taubert ◽  
James H. Ferris ◽  
Karen I. Winey
Keyword(s):  
Sample Preparation ◽  
Polymer Films ◽  
Free Standing ◽  
Rapid Preparation ◽  
Cross Sectional ◽  
Thin Sections ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Brittle Polymers

Polymer films and fibers can readily be imaged in a “top-view“ mode by depositing the sample directly on a transmission electron microscopy (TEM) support grid. Sample preparation of thin polymer films and fibers for cross-sectional views in the electron microscope, however, is a major challenge. Owing to their small dimensions, the films or fibers cannot be mounted alone, because they will not remain immobilized In the microtome, even at low temperatures. Brittle polymers complicate sample preparation even further because they tend to break due to the mechanical stresses exerted on them by the microtome sample holder and the knife. Such sections often jump off the knife-edge or the sample film, thus preventing a systematic collection of thin sections. Similar arguments apply for cross-sectional atomic force microscopy (AFM).

Scanning tunneling microscopy and atomic force microscopy: New tools for biology

1989 ◽  
Vol 47 ◽  
pp. 778-779
Author(s):  
CE Bracker ◽  
P. K. Hansma
Keyword(s):  
Physical Property ◽  
Scanning Probe ◽  
Scanning Tunneling ◽  
Small Scale ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
New Family ◽  
Small Probe ◽  
Atomic Force ◽  
Transmission Electron

A new family of scanning probe microscopes has emerged that is opening new horizons for investigating the fine structure of matter. The earliest and best known of these instruments is the scanning tunneling microscope (STM). First published in 1982, the STM earned the 1986 Nobel Prize in Physics for two of its inventors, G. Binnig and H. Rohrer. They shared the prize with E. Ruska for his work that had led to the development of the transmission electron microscope half a century earlier. It seems appropriate that the award embodied this particular blend of the old and the new because it demonstrated to the world a long overdue respect for the enormous contributions electron microscopy has made to the understanding of matter, and at the same time it signalled the dawn of a new age in microscopy. What we are seeing is a revolution in microscopy and a redefinition of the concept of a microscope.Several kinds of scanning probe microscopes now exist, and the number is increasing. What they share in common is a small probe that is scanned over the surface of a specimen and measures a physical property on a very small scale, at or near the surface. Scanning probes can measure temperature, magnetic fields, tunneling currents, voltage, force, and ion currents, among others.

The Electrical Characterization and Physical Failure Analysis for Transistor Gate Leakage

2006 ◽  
Author(s):  
Tsung-Te Li ◽  
Chao-Chi Wu ◽  
Jung-Hsiang Chuang ◽  
Jon C. Lee
Keyword(s):  
Failure Analysis ◽  
Electrical Characterization ◽  
Physical Analysis ◽  
Gate Leakage ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Voltage Stress ◽  
Leakage Site

Abstract This article describes the electrical and physical analysis of gate leakage in nanometer transistors using conducting atomic force microscopy (C-AFM), nano-probing, transmission electron microscopy (TEM), and chemical decoration on simulated overstressed devices. A failure analysis case study involving a soft single bit failure is detailed. Following the nano-probing analysis, TEM cross sectioning of this failing device was performed. A voltage bias was applied to exaggerate the gate leakage site. Following this deliberate voltage overstress, a solution of boiling 10%wt KOH was used to etch decorate the gate leakage site followed by SEM inspection. Different transistor leakage behaviors can be identified with nano-probing measurements and then compared with simulation data for increased confidence in the failure analysis result. Nano-probing can be used to apply voltage stress on a transistor or a leakage path to worsen the weak point and then observe the leakage site easier.

Structural and Optical Properties of InAsSbBi Grown by Molecular Beam Epitaxy on Offcut GaSb Substrates

Photonics ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 215
Author(s):  
Rajeev R. Kosireddy ◽  
Stephen T. Schaefer ◽  
Marko S. Milosavljevic ◽  
Shane R. Johnson
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Optical Quality ◽  
X Ray Diffraction ◽  
Interface Quality ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Lateral Variations

Three InAsSbBi samples are grown by molecular beam epitaxy at 400 °C on GaSb substrates with three different offcuts: (100) on-axis, (100) offcut 1° toward [011], and (100) offcut 4° toward [011]. The samples are investigated using X-ray diffraction, Nomarski optical microscopy, atomic force microscopy, transmission electron microscopy, and photoluminescence spectroscopy. The InAsSbBi layers are 210 nm thick, coherently strained, and show no observable defects. The substrate offcut is not observed to influence the structural and interface quality of the samples. Each sample exhibits small lateral variations in the Bi mole fraction, with the largest variation observed in the on-axis growth. Bismuth rich surface droplet features are observed on all samples. The surface droplets are isotropic on the on-axis sample and elongated along the [011¯] step edges on the 1° and 4° offcut samples. No significant change in optical quality with offcut angle is observed.

Microscopic studies of fast phase transformations in GeSbTe films

2001 ◽  
Vol 674 ◽  
Author(s):  
Ralf Detemple ◽  
Inés Friedrich ◽  
Walter Njoroge ◽  
Ingo Thomas ◽  
Volker Weidenhof ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Data Transfer ◽  
Optical Measurements ◽  
Transfer Rates ◽  
Force Microscopy ◽  
High Data ◽  
Atomic Force ◽  
Transmission Electron ◽  
Future Success ◽  
Microscopic Studies

ABSTRACTVital requirements for the future success of phase change media are high data transfer rates, i.e. fast processes to read, write and erase bits of information. The understanding and optimization of fast transformations is a considerable challenge since the processes only occur on a submicrometer length scale in actual bits. Hence both high temporal and spatial resolution is needed to unravel the essential details of the phase transformation. We employ a combination of fast optical measurements with microscopic analyses using atomic force microscopy (AFM) and transmission electron microscopy (TEM). The AFM measurements exploit the fact that the phase transformation from amorphous to crystalline is accompanied by a 6% volume reduction. This enables a measurement of the vertical and lateral speed of the phase transformation. Several examples will be presented showing the information gained by this combination of techniques.

Defect-Engineered Graded GexSi1-x Buffers on Si (001) with Extreme Low Threading Dislocation Density

1995 ◽  
Vol 378 ◽  
Author(s):  
G. Kissinger ◽  
T. Morgenstern ◽  
G. Morgenstern ◽  
H. B. Erzgräber ◽  
H. Richter
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atomic Force Microscopy ◽  
Dislocation Density ◽  
Threading Dislocation ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Threading Dislocation Density

AbstractStepwise equilibrated graded GexSii-x (x≤0.2) buffers with threading dislocation densities between 102 and 103 cm−2 on the whole area of 4 inch silicon wafers were grown and studied by transmission electron microscopy, defect etching, atomic force microscopy and photoluminescence spectroscopy.

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