Showing papers by "University of Jordan published in 1975"
TL;DR: In this paper, high-resolution defocusing phase contrast electron microscopy has been used for structural studies of carbon fibres from a range of precusor materials, such as poly-acrylonitrile (PAN)-based carbon fiber, to detect variations in structure which give rise to abnormal physical properties.
Abstract: RECENT developments in our understanding and application of high-resolution defocusing phase contrast electron microscopy have contributed significantly to structural studies of carbon fibres from a range of precusor materials1–4. For example, we are now able to follow the natural pattern of carbonisation in the standard commercial process for poly-acrylonitrile (PAN)-based carbon fibres, and to detect variations in structure which give rise to abnormal physical properties5,6. One major factor which has influenced the success of the work on carbon fibres is the stability of the stacked carbon ribbons to irradiation by an electron beam, and the relative ease with which the {002} lattice fringes can be recorded. In fibrous organic polymers we have observed massive degradation of structural order as revealed by the rapid deterioration of the electron-diffraction pattern7,8; this has precluded the recording of lattice-fringe images and so prevented the breakthrough in understanding which would undoubtedly follow as a result of direct observation of fibre structure at the molecular level.
48 citations
TL;DR: The reversible reactions of several cyclic anhydrides with acetic acid to form acetic anhydride and the corresponding dicarboxylic acid, catalyzed by perchloric acid at 25degree, were studied and the reverse rate constants were found to be relatively independent of the structure of the attacking diacid.
17 citations
TL;DR: In this paper, the structure of tetrakis(biuret)strontium(II) perchlorate, [Sr((NH 2 CO) 2 NH) 4 ](ClO 4 ) 2, was determined using the Patterson and Fourier methods and refined by diagonal least squares to an R factor of 0.094.
7 citations
TL;DR: In this paper, the endo confrontation of monoacyl and 1,3-diacyl-1,2-dihydrobenzimidazoles was found to be dominant at ambient temperatures.
6 citations
TL;DR: The formation of phenyl acetate as the major reaction product could be rationalized as being due to the reactivity of the cyclic anhydrides with acetic acid to form acetic anhydride as well as the greater reactsivity of phenol with formed aceticAnhydride than with the cyclohexanedicarboxylic anhydrid.
1 citations
TL;DR: In this article, the authors have studied the reactions Nien 2 2+ → Nien(H 2 O) 2 2 + and Nien2 2+→ NienCl 2 (en = ethylenediamine) in aqueous solution with ionic strength 1·0 M.
1 citations
TL;DR: Chebyshev polynomials have been used for the on-line determination of the Michaelis-Menton constant, K m, and the maximum velocity, V max for four enzymes.