Tens Angstroms

Woodward RP (2000) Cleanliness measurement using crmtact angles. First Ten Angstroms, Portsmouth... 

Type 13X (ten angstroms). Type 13X is a modified form of the sodium zeolite with a pore diameter of ten angstroms. Molecules of chloroform, carbon tetrachloride and benzene can be adsorbed on type 13X molecular sieves. Type 13X is used commercially for general gas drying, air plant feed purification (i.e., simultaneous removal of H O and CO ) and liquid hydrocarbon and natural gas sweetening (i.e., H S and mercaptan removal). All molecules which can be adsorbed on molecular sieves 3A, 4A and 5A can be adsorbed on type 13X. In addition, type 13X can adsorb molecules of larger critical diameters, such as aromatics and branched-chain hydrocarbons. 

Woodward, R.P., 2010. Surface tension measurement using the drop shape method. Firsttenangstroms. com. First Ten Angstroms. Web. http //www.firsttenangstroms.com/pdfdocs/STPaper.pdf. 

It would be difficult to over-estimate the extent to which the BET method has contributed to the development of those branches of physical chemistry such as heterogeneous catalysis, adsorption or particle size estimation, which involve finely divided or porous solids in all of these fields the BET surface area is a household phrase. But it is perhaps the very breadth of its scope which has led to a somewhat uncritical application of the method as a kind of infallible yardstick, and to a lack of appreciation of the nature of its basic assumptions or of the circumstances under which it may, or may not, be expected to yield a reliable result. This is particularly true of those solids which contain very fine pores and give rise to Langmuir-type isotherms, for the BET procedure may then give quite erroneous values for the surface area. If the pores are rather larger—tens to hundreds of Angstroms in width—the pore size distribution may be calculated from the adsorption isotherm of a vapour with the aid of the Kelvin equation, and within recent years a number of detailed procedures for carrying out the calculation have been put forward but all too often the limitations on the validity of the results, and the difficulty of interpretation in terms of the actual solid, tend to be insufficiently stressed or even entirely overlooked. And in the time-honoured method for the estimation of surface area from measurements of adsorption from solution, the complications introduced by... 

This estimate should be accurate if the droplet is sufficiently large (a few tens of angstroms). 

The boundary layers, or interphases as they are also called, form the mesophase with properties different from those of the bulk matrix and result from the long-range effects of the solid phase on the ambient matrix regions. Even for low-molecular liquids the effects of this kind spread to liquid layers as thick as tens or hundreds or Angstrom [57, 58], As a result the liquid layers at interphases acquire properties different from properties in the bulk, e.g., higher shear strength, modified thermophysical characteristics, etc. [58, 59], The transition from the properties prevalent in the boundary layers to those in the bulk may be sharp enough and very similar in a way to the first-order phase transition [59]. 

Angstrom unit (A) A unit of length, one ten-millionth of a millimeter or one ten-thousandth of a micrometer long, anhydrous Without water, animal fibers See fibers, animal. anion An ion having a negative electric charge. 

Chou and Wollast (23) challenged XPS studies which indicate that incongruent surface layers thicker than several Angstroms do not exist. They argue that material balance calculations require some sort of altered layer in order to account for the observed incongruency between alkalis, silica, and aluminum. Their material balance calculations suggest that the layer thickness must be on the order of only tens of nanometers, which, despite their arguments to the contrary, is not inconsistent with the surface chemistry observations (e.g., XPS) they seek to refute. 

Advanced materials stmcture analysis by electron diffraction in a TEM presents a lot of advantages over conventional X-Ray diffraction the size of studied crystallites in TEM can be very small (even tens of Angstroms), therefore individual phases in Industrial powders (nm size) can be examined. 

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