A New Method for Measuring the Surface Areas of Finely Divided Materials and for Determining the Size of Particles

Author(s):  
P. H. Emmett
2010 ◽  
Vol 125 (Supplement) ◽  
pp. 64
Author(s):  
KC Neaman ◽  
LA Andres ◽  
AM McClure ◽  
ME Burton ◽  
PR Kemmeter ◽  
...  

2015 ◽  
Author(s):  
◽  
Elmar Dohnke

The commercialization of hydrogen-powered fuel cell cars, with their environmentally friendly emissions, provides an opportunity to replace current gasoline powered vehicles. The main drawback of hydrogen as a fuel is the low density at ambient temperatures. The gas needs to be compressed to high pressure or kept under cryogenic temperatures to achieve reasonably long driving ranges. These obstacles can be overcome if the tanks are filled with a porous material that adsorbs a high volume of hydrogen. Many materials are put forward for this purpose, such as metal organic frameworks (MOFs) and engineered carbon nanospaces (synthetic carbon). To get a better understanding of the materials performance, an attempt was made to analyze the properties of the adsorbed hydrogen film. High pressure hydrogen isotherms at cryogenic temperatures (77 K, 50 K) have been studied to estimate adsorbed film properties such as density and thickness. Furthermore, how isosteric heat of adsorption, surface chemistry, and pore size distribution affect the adsorbed film has been investigated. At supercritical temperatures and high pressures, a film density 20% higher than liquid hydrogen at 1 bar and 20 K was obtained. These densities are independent of the isosteric heat of adsorption or pore size distribution. The adsorbed film densities behave similarly for all carbon-based surfaces at 77 K. Additionally a new method was developed to estimate specific surface areas of gas storage materials from high pressure isotherms and tested against the BET theory. The new method does not require knowledge of the packing fraction or cross-sectional area of an adsorbed molecule in the film. In most cases the new method leads to surface areas comparable to those found using BET theory if cryogenic high pressure isotherms are used. A new manometric (Sieverts type) adsorption instrument was designed and test, capable of measuring sub- and supercritical hydrogen isotherms at high pressure.


Author(s):  
R.F. Dodson ◽  
L.W-F Chu ◽  
N. Ishihara

The extent of damage surrounding an implanted electrode in the cerebral cortex is a question of significant importance with regard to attaining consistency and validity of physiological recordings. In order to determine the extent of such tissue changes, 150 micron diameter platinum electrodes were implanted in the cortex of four adult baboons, and after eight days the animals were sacrificed by whole body perfusion with a 3% glutaraldehyde in 0.1M phosphate fixative.The calvarium was carefully removed and the electrode tracts were readily discernible in the firm, glutaraldehyde fixed tissue.Careful dissection of the zone of the electrode tract resulted in a small block which was further sectioned into tip, mid-tract and surface areas. Ultrastructurally, damage extended from the electrode sheath to the greatest extent of from 0.2 to 3.5 mm.


Author(s):  
Adrian F. van Dellen

The morphologic pathologist may require information on the ultrastructure of a non-specific lesion seen under the light microscope before he can make a specific determination. Such lesions, when caused by infectious disease agents, may be sparsely distributed in any organ system. Tissue culture systems, too, may only have widely dispersed foci suitable for ultrastructural study. In these situations, when only a few, small foci in large tissue areas are useful for electron microscopy, it is advantageous to employ a methodology which rapidly selects a single tissue focus that is expected to yield beneficial ultrastructural data from amongst the surrounding tissue. This is in essence what "LIFTING" accomplishes. We have developed LIFTING to a high degree of accuracy and repeatability utilizing the Microlift (Fig 1), and have successfully applied it to tissue culture monolayers, histologic paraffin sections, and tissue blocks with large surface areas that had been initially fixed for either light or electron microscopy.


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