On influence of residual atmosphere on results of investigation of thermal treatment in an electron microscope

Silica in nanoscale has various superior properties which leads to a wide range of applications. Most researches used and metal alkoxides as the sources but very few researches attempted at preparing nanosilica powder from the agricultural waste which environmental friendly and inexpensive. This research is presented as the studies of optimization of parameters involved during preparation, aimed to improve the purity of silica produced. In this work, rice husk ash (RHA) precursor was subjected to precipitation method in order to produce nanosilica powder. Acid leaching and thermal treatment were done as a pre-synthesis process. The process parameters that have been studied were the refluxed NaOH concentration, heating time, and temperature, in which the properties were then evaluated during characterization process. The results from X-Ray Flourescence (XRF) confirmed that it is possible to extract 100% purity of silica from RHA treated by the combination of thermal treatment, acid leaching, refluxed with 2.5 M of NaOH and heated at 50°C for 48 hours. X-Ray Diffraction (XRD) illustrated that the produced silica is in amorphous state. Meanwhile, the mean particle size of the spherical shape of silica obtained ranging from 44.7 nm to 1.23 μm. Therefore, the best mean particle size obtained was by using the sample refluxed with 2.5 M NaOH and heated at 50°C for 48 hours, which were confirmed by Scanning Electron Microscope (SEM) and Field Emission Scanning Electron Microscope (FESEM). These findings on the optimum parameters indicate the successful production of highest purity of nanosilica powder with nanoscaled particle size.

Download Full-text

Electron Cytochemical Study of Carbon Dioxide Laser Effect on Rhesus Monkey Cornea

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010005113x ◽

1974 ◽

Vol 32 ◽

pp. 224-225

Author(s):

K. C. Tsou ◽

J. Morris ◽

P. Shawaluk ◽

B. Stuck ◽

E. Beatrice

Keyword(s):

Carbon Dioxide ◽

Electron Microscope ◽

Rhesus Monkey ◽

Carbon Dioxide Laser ◽

Cytochemical Study ◽

Laser Effect

While much is known regarding the effect of lasers on the retina, little study has been done on the effect of lasers on cornea, because of the limitation of the size of the material. Using a combination of electron microscope and several newly developed cytochemical methods, the effect of laser can now be studied on eye for the purpose of correlating functional and morphological damage. The present paper illustrates such study with CO2 laser on Rhesus monkey.

Download Full-text

A Reproducible Selective Stain for Cardiac Sarcoplasmic Reticulum

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100051086 ◽

1974 ◽

Vol 32 ◽

pp. 214-215

Author(s):

R. A. Waugh ◽

J. R. Sommer

Keyword(s):

Complex System ◽

Electron Microscope ◽

Sarcoplasmic Reticulum ◽

Transmission Electron Microscope ◽

Electron Microscopic ◽

Cardiac Sarcoplasmic Reticulum ◽

Transmission Electron

Cardiac sarcoplasmic reticulum (SR) is a complex system of intracellular tubules that, due to their small size and juxtaposition to such electron-dense structures as mitochondria and myofibrils, are often inconspicuous in conventionally prepared electron microscopic material. This study reports a method with which the SR is selectively “stained” which facilitates visualizationwith the transmission electron microscope.

Download Full-text

Utilizing Dark Field Electron Microscopy to Produce Lantern Slides

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100050597 ◽

1974 ◽

Vol 32 ◽

pp. 116-117

Author(s):

J. N. Meador ◽

C. N. Sun ◽

H. J. White

Keyword(s):

Electron Microscope ◽

Electron Micrographs ◽

Dark Field ◽

Limiting Factor ◽

Clinical Laboratories ◽

Field Electron ◽

Time Element ◽

Field Electron Microscopy ◽

Dark Field Electron ◽

Dark Field Micrographs

The electron microscope is being utilized more and more in clinical laboratories for pathologic diagnosis. One of the major problems in the utilization of the electron microscope for diagnostic purposes is the time element involved. Recent experimentation with rapid embedding has shown that this long phase of the process can be greatly shortened. In rush cases the making of projection slides can be eliminated by taking dark field electron micrographs which show up as a positive ready for use. The major limiting factor for use of dark field micrographs is resolution. However, for conference purposes electron micrographs are usually taken at 2.500X to 8.000X. At these low magnifications the resolution obtained is quite acceptable.

Download Full-text

Observation of biological macromolecules using various electron microscopic methods

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100081711 ◽

1978 ◽

Vol 36 (2) ◽

pp. 170-171

Author(s):

Mitsuo Ohtsuki ◽

Michael Sogard

Keyword(s):

Electron Microscope ◽

Phase Contrast ◽

Image Interpretation ◽

Density Lipoprotein ◽

Biological Macromolecules ◽

Contrast Effects ◽

Biological Structure ◽

Electron Microscopic ◽

Structural Investigations ◽

Staining Techniques

Structural investigations of biological macromolecules commonly employ CTEM with negative staining techniques. Difficulties in valid image interpretation arise, however, due to problems such as variability in thickness and degree of penetration of the staining agent, noise from the supporting film, and artifacts from defocus phase contrast effects. In order to determine the effects of these variables on biological structure, as seen by the electron microscope, negative stained macromolecules of high density lipoprotein-3 (HDL3) from human serum were analyzed with both CTEM and STEM, and results were then compared with CTEM micrographs of freeze-etched HDL3. In addition, we altered the structure of this molecule by digesting away its phospholipid component with phospholipase A2 and look for consistent changes in structure.

Download Full-text

Immune electron microscopy of haemocyanins from two southern african whelks

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100081656 ◽

1978 ◽

Vol 36 (2) ◽

pp. 158-159

Author(s):

Linda M. Stannard ◽

Margaret Lennon

Keyword(s):

Electron Microscopy ◽

Electron Microscope ◽

Outer Ring ◽

Immune Electron Microscopy ◽

Intertidal Zones ◽

Central Belt ◽

Cape Peninsula ◽

Circular Contour

Burnupena cincta and Fusus verruculatus are two whelks which inhabit the intertidal zones of the Cape Peninsula shore. Their respiratory pigments, or haemocyanins, are morphologically similar in structure (Figs. 1 and 2) and appear in the electron microscope as short cylindrical rods about 34 nm in diameter and 36 nm high. Viewed side-on the molecules show regular banding suggesting a structure composed of six equidistant rings of sub-units. Occasionally the particles have the appearance of possessing a central “belt” in the position of the 3rd and 4th rows of sub-units. End-on views of the haemocyanin molecules show a circular contour with a dense outer ring and a less dense inner ring in which 10 definite sub-units may frequently be distinguished. A number of molecules display an extra central inner component which appears either as a diffuse plug or as a discrete ring-shaped core ± 8 nm in diameter.

Download Full-text

Evaluation of single-electron movies of glutamine synthetase molecules

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100075191 ◽

1983 ◽

Vol 41 ◽

pp. 280-281

Author(s):

W. Kunath ◽

E. Zeitler ◽

M. Kessel

Keyword(s):

Electron Microscope ◽

Glutamine Synthetase ◽

Electron Irradiation ◽

Structural Damage ◽

Structural Changes ◽

Single Electron ◽

Continuous Series ◽

Digital Recording ◽

Recording Device ◽

Low Exposure

The features of digital recording of a continuous series (movie) of singleelectron TV frames are reported. The technique is used to investigate structural changes in negatively stained glutamine synthetase molecules (GS) during electron irradiation and, as an ultimate goal, to look for the molecules' “undamaged” structure, say, after a 1 e/Å2 dose.The TV frame of fig. la shows an image of 5 glutamine synthetase molecules exposed to 1/150 e/Å2. Every single electron is recorded as a unit signal in a 256 ×256 field. The extremely low exposure of a single TV frame as dictated by the single-electron recording device including the electron microscope requires accumulation of 150 TV frames into one frame (fig. lb) thus achieving a reasonable compromise between the conflicting aspects of exposure time per frame of 3 sec. vs. object drift of less than 1 Å, and exposure per frame of 1 e/Å2 vs. rate of structural damage.

Download Full-text

Morphology, Distribution and Identification of Micro-Constituents Along Grain Boundaries in Nickel-Base Alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071326 ◽

1973 ◽

Vol 31 ◽

pp. 176-177

Author(s):

D. E. Fornwalt ◽

A. R. Geary ◽

B. H. Kear

Keyword(s):

Electron Microscope ◽

Grain Boundaries ◽

Volume Fraction ◽

Rupture Life ◽

Stress Rupture ◽

High Volume ◽

Precipitate Morphology ◽

Stress Rupture Life ◽

Nickel Base ◽

Scanning Electron

A systematic study has been made of the effects of various heat treatments on the microstructures of several experimental high volume fraction γ’ precipitation hardened nickel-base alloys, after doping with ∼2 w/o Hf so as to improve the stress rupture life and ductility. The most significant microstructural chan§e brought about by prolonged aging at temperatures in the range 1600°-1900°F was the decoration of grain boundaries with precipitate particles.Precipitation along the grain boundaries was first detected by optical microscopy, but it was necessary to use the scanning electron microscope to reveal the details of the precipitate morphology. Figure 1(a) shows the grain boundary precipitates in relief, after partial dissolution of the surrounding γ + γ’ matrix.

Download Full-text