Water in sphere-type opal

1969 ◽  
Vol 37 (287) ◽  
pp. 357-361 ◽  
Author(s):  
J. B. Jones ◽  
E. R. Segnit
Keyword(s):  
Electron Microscopy ◽  
Surface Area ◽  
Electron Micrographs ◽  
Thermal Dehydration ◽  
Nitrogen Absorption ◽  
Surface Areas ◽  
Resolution Electron ◽  
Apparent Inconsistency

SummarySurface areas of ‘amorphous’-type opals measured by nitrogen-absorption techniques were not consistent either with the surface area of the spheres of about 2000 Å diameter observable by electron microscopy or with the thermal dehydration data. This apparent inconsistency can be explained in terms of a smaller particulate structure of the order of 100–200 Å shown by higher resolution electron micrographs. This structure also accounts for a marked shrinkage shown in dilatometer curves of this type of opal.

Cell morphology, volume, and surface area determinations from multilevel contouring within HVEM micrographs of serial sections and whole-cell mounts

1987 ◽  
Vol 45 ◽  
pp. 588-589
Author(s):  
M. Marko ◽  
A. Leith ◽  
D. Parsons
Keyword(s):  
Surface Area ◽  
Electron Micrographs ◽  
Cell Morphology ◽  
Individual Variation ◽  
Serial Section ◽  
Stereo Pair ◽  
Complex Structures ◽  
Serial Sections ◽  
Surface Areas ◽  
Computer Based

The use of serial sections and computer-based 3-D reconstruction techniques affords an opportunity not only to visualize the shape and distribution of the structures being studied, but also to determine their volumes and surface areas. Up until now, this has been done using serial ultrathin sections.The serial-section approach differs from the stereo logical methods of Weibel in that it is based on the Information from a set of single, complete cells (or organelles) rather than on a random 2-dimensional sampling of a population of cells. Because of this, it can more easily provide absolute values of volume and surface area, especially for highly-complex structures. It also allows study of individual variation among the cells, and study of structures which occur only infrequently.We have developed a system for 3-D reconstruction of objects from stereo-pair electron micrographs of thick specimens.

TEM measurement of surface area of automotive catalysts

1994 ◽  
Vol 52 ◽  
pp. 776-777
Author(s):  
M. H. Yao ◽  
D. R. Liu ◽  
R. J. Baird ◽  
R. K. Usmen ◽  
R. W. McCabe
Keyword(s):  
Electron Microscopy ◽  
Surface Area ◽  
Average Particle Size ◽  
Weighted Average ◽  
Average Particle ◽  
Automotive Catalysts ◽  
Surface Areas ◽  
Measuring Surface ◽  
Major Factors ◽  
Average Size

The specific surface area of supported noble metal particles in an automotive catalyst is defined as the exposed surface area per unit mass of these particles. It is of great importance to know this parameter, since this is one of the major factors that determine the effectiveness of the catalyst. Commonly used methods for characterizing catalysts, such as X-ray diffraction and TEM, do not directly provide a measure of surface area, but, instead, provide a measure of the “average size” of supported particles. Moreover, the “average sizes” obtained from different experimental techniques are often not comparable. Furthermore, many previous electron microscopy catalyst studies measured only simple average particle size, and no detailed procedure for measuring area-weighted average size or surface area appear to have been reported.In the current study, a procedure for measuring surface area of supported particles by transmission electron microscopy(TEM) was developed, and applied to measure surface areas of various production three-way automotive catalysts.

Application of the imaging plate to quantitative analysis of electron-diffraction and high-resolution electron microscopy

1989 ◽  
Vol 47 ◽  
pp. 666-667
Author(s):  
K. Hiraga ◽  
D. Shindo ◽  
M. Hirabayashi ◽  
T. Oikawa ◽  
N. Mori ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Quantitative Analysis ◽  
High Resolution ◽  
Electron Diffraction ◽  
Electron Micrographs ◽  
High Resolution Electron Microscopy ◽  
Imaging Plate ◽  
Resolution Electron ◽  
Diffraction Patterns ◽  
High Resolution Electron Micrographs

The “Imaging Plate” (IP) has three superior characteristics, i.e., high sensitivity to the electron beam, and a wide dynamic range and good linearity for electron dose compared with conventional EM films. The use of the IP is expected to lead to quantitative analysis of electron microscopy. The purpose of the present work is to examine the possibility of application of the IP to the quantitative analysis of electron diffraction and high-resolution electron microscopy.By using the TEM-IP System developed by Oikawa et al., which is published in this conference, electron diffraction patterns and high-resolution electron micrographs taken on the IP with an effective size of 102 х 77 mm2 were convertedinto digital data of 2048 х 1536 pixels with 4096 gray levels. Observations of electron diffraction patterns and high-resolution electron micrographs were made with a 200 kV (JEM-2000FX) and a 400 kV (JEM-4000EX) electron microscope, respectively.

Structure Imaging and Defects in Crystallized Oxynitride Glasses

1986 ◽  
Vol 82 ◽  
Author(s):  
R.S. Rai ◽  
M.A. O'Keefe ◽  
G. Thomas
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Computer Simulations ◽  
Electron Micrographs ◽  
High Resolution Electron Microscopy ◽  
Space Groups ◽  
Cell Parameters ◽  
Resolution Electron ◽  
Structural Details ◽  
High Resolution Electron Micrographs

ABSTRACTHigh resolution electron microscopy has been employed to elucidate fault defects and structural details of the δ1 and δ2-Y2Si2O7 crystalline phases. From this study δ1 and δ2-Y2Si2O7 have been found to be orthorhombic having the same cell parameters but different atomic arrangements due to a change in their space groups. Computer simulations were necessary for interpreting details from the high resolution electron micrographs.

Formation and processing of mesoporous barium titanate powders via the micelle template method

2006 ◽  
Vol 21 (4) ◽  
pp. 941-946
Author(s):  
Hong-Wen Wang ◽  
Chien-Hung Kuo ◽  
Tsai-Huei Liao ◽  
Ren-Jay Lin ◽  
Syh-Yuh Cheng
Keyword(s):  
Electron Microscopy ◽  
Barium Titanate ◽  
Surface Area ◽  
Self Assembly ◽  
Structural Characteristics ◽  
Mesoporous Structure ◽  
Surface Areas ◽  
Transmission Electron ◽  
Organic Surfactant ◽  
Titanium Tetra Isopropoxide

Mesoporous barium titanate powders having a 100- to 300-nm size were prepared by hydration and condensation of titanium tetra-isopropoxide and barium precursors in the presence of an organic surfactant, tetradecylamine, which was used as a self-assembly micelle. The processing and sintering of these mesoporous barium titanate powders has been investigated. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to identify the structural characteristics and morphologies of the powders. Mesoporous wormhole-like powders with surface areas around 53 ∼ 108 m2/g could be obtained after removing the micelle organics by calcination at 400 °C for 3 h. Powders derived using barium hydroxide were found to form a larger pore size and a higher surface area. The addition of acetic acid was also effective in increasing the surface area. A formation mechanism for the mesoporous structure is depicted. Heat treatment caused the mesoporous spheres to shrink, and 155- ∼ 330-nm grain sizes were readily obtained after pressureless sintering at 900 ∼ 1000 °C for 1 h in air.

Comparison of Geometric and “Real” Surface Areas of Cochlear Electrodes

1983 ◽  
Vol 91 (4) ◽  
pp. 417-420 ◽  
Author(s):  
Franklin M. Rizer ◽  
Larry G. Duckert ◽  
Francis A. Spelman
Keyword(s):  
Electron Microscopy ◽  
Charge Density ◽  
Surface Area ◽  
Surface Charge Density ◽  
Real Surface ◽  
Active Electrode ◽  
Surface Areas ◽  
Tissue Surface ◽  
Destructive Potential ◽  
Scanning Electron

The destructive potential of the electrically active electrode is believed to be related to charge density at the electrode-tissue surface. Charge density has been calculated with the use of both geometric and electrochemical “real” values for surface area. To further assess the accuracy of surface area measurements determined by means of the previously mentioned methods, an eight-electrode modiolar array cochlear implant was examined. Electrode surface areas were measured first electrochemically, then by means of a light microscope, and finally with the use of the scanning electron microscope. Comparison of these measurements demonstrated a high correlation between the scanning and light microscopic values. However, there was no correlation between the surface areas determined by light and scanning electron microscopy and the electrochemical measurements.

scholarly journals Disappearance of macrophage surface folds after antibody-dependent phagocytosis.

1981 ◽  
Vol 89 (2) ◽  
pp. 223-229 ◽  
Author(s):  
H R Petty ◽  
D G Hafeman ◽  
H M McConnell
Keyword(s):  
Electron Microscopy ◽  
Cell Surface ◽  
Guinea Pig ◽  
Surface Area ◽  
Surface Membrane ◽  
Peritoneal Macrophages ◽  
Injection Technique ◽  
Surface Areas ◽  
Transmission Electron ◽  
Uptake Data

We have employed the method of Burwen and Satir (J. Cell Biol., 1977, 74:690) to measure the disappearance of surface folds from resident guinea pig peritoneal macrophages after antibody-dependent phagocytosis. Unilamellar phospholipid vesicles containing dimyristoylphosphatidylcholine and 1 mol % dinitrophenyl-epsilon-aminocaproyl-phosphatidylethanolamine, a lipid that possesses a hapten headgroup, were prepared by an ether injection technique. These vesicles were taken up by macrophages in a time- and temperature-dependent fashion. Vesicles that contained ferritin trapped in the internal aqueous volume were identified within macrophages by transmission electron microscopy. Scanning electron microscopy has shown that macrophage surface folds decrease dramatically after phagocytosis. The surface fold length (micrometer) per unit smooth sphere surface area (micrometer2) decreases from 1.3 +/- 0.3 micrometer-1 to 0.53 +/- 0.25 micrometer-1 when cells are incubated in the presence of specific anti-DNP antibody and vesicles at 37 degrees C. No significant effect was observed in the presence of antibody only or vesicles only. Our studies shown that phagocytosis is associated with a loss of cell surface folds and a loss of cell surface area, which is consonant with current views of the endocytic process. On the basis of our uptake data, we estimate that approximately 400 micrometer2 of vesicle surface membrane is internalized. The guinea pig macrophage plasma membrane has a total area of approximately 400 micrometer2 in control studies, whereas the cells have roughly 300 micrometer2 after phagocytosis. These estimates of surface areas include membrane ruffles and changes directly related to changes in cell volume. We suggest that during antibody-dependent phagocytosis a membrane reservoir is made available to the cell surface.

scholarly journals Synthesis of Monolithic TiO2 Aerogels With Relatively Low Shrinkage and Improved Formability Assisted by CTAB

2021 ◽  
Vol 8 ◽  
Author(s):  
Tingting Niu ◽  
Bin Zhou ◽  
Zehui Zhang ◽  
Jianming Yang ◽  
Xiujie Ji ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
Supercritical Drying ◽  
High Specific Surface Area ◽  
Structure Property ◽  
Surface Areas ◽  
Polycondensation Process

Monolithic TiO2 aerogels without severe shrink were obtained by the sol-gel method with the addition of the surfactant cetyltrimethylammonium bromide (CTAB) to control the hydrolysis and polycondensation process and acetonitrile solvent as the solvent to improve the crystallinity. After CO2 supercritical drying, the shrinkage ratio of monolithic TiO2 aerogels modified by CTAB decreased by up to ∼26.9%, compared with the pure TiO2 aerogel. Their apparent densities were all lower than 300 g/cm3. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform infrared spectroscopy (FTIR) and BET Specific Surface Area Analysis were used to analyze the as-synthesized samples. The results revealed that all the samples were anatase-TiO2 phase with nanoporous network structures. The specific surface areas reached 250.2 m2/g confirmed by the BET (Brunaur–Emmett–Teller method) analysis. However, TiO2 aerogels without the addition of CTAB showed evident agglomeration and collapse of the network in comparison with CTAB-added samples. To further study the structure-property relationship, the photocatalysis performance of as-synthesized and 300°C-calcined aerogels was carried out contrastively. Interestingly, the influences of the CTAB adding amount of as-synthesized and calcined TiO2 aerogels are negative and positive, respectively, which is probably due to the synergistic effect of CTAB hindrance and grain refinement. Potentially, This kind of TiO2 aerogels assisted by CATB with low density, small shrinkage, improved formability, high specific surface area and fine crystalline grain may be applied in various applications, such as electrochemistry, photocatalysis, etc.

Light Optical Diffraction Studies of Macromolecular Ultrastructure

1970 ◽  
Vol 28 ◽  
pp. 258-259
Author(s):  
Glen B. Haydon
Keyword(s):  
High Resolution ◽  
Diffraction Analysis ◽  
Diffraction Pattern ◽  
Electron Micrographs ◽  
Optical Diffraction ◽  
Electron Micrograph ◽  
Its Analysis ◽  
Resolution Electron ◽  
Diffraction Patterns

Analysis of light optical diffraction patterns produced by electron micrographs can easily lead to much nonsense. Such diffraction patterns are referred to as optical transforms and are compared with transforms produced by a variety of mathematical manipulations. In the use of light optical diffraction patterns to study periodicities in macromolecular ultrastructures, a number of potential pitfalls have been rediscovered. The limitations apply to the formation of the electron micrograph as well as its analysis.(1) The high resolution electron micrograph is itself a complex diffraction pattern resulting from the specimen, its stain, and its supporting substrate. Cowley and Moodie (Proc. Phys. Soc. B, LXX 497, 1957) demonstrated changing image patterns with changes in focus. Similar defocus images have been subjected to further light optical diffraction analysis.

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