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JournalISSN: 0301-7249

Faraday Discussions of The Chemical Society 

Royal Society of Chemistry
About: Faraday Discussions of The Chemical Society is an academic journal. The journal publishes majorly in the area(s): Excited state & van der Waals force. Over the lifetime, 885 publications have been published receiving 33807 citations.


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TL;DR: The polyanilines are a class of polymers the base form of which has the general formula [graphic omitted] containing y reduced and (1 -y) oxidized repeat groups.
Abstract: The polyanilines are a class of polymers the base form of which has the general formula [graphic omitted] containing y reduced and (1 –y) oxidized repeat groups. y can in principle be varied continuously from one, the completely reduced material, to zero to give the completely oxidized polymer. The emeraldine oxidation state (y= 0.5) consists of alternating reduced and oxidized groups. It can be protonated, i.e. doped, by aqueous acids with a concomitant increase in conductivity of almost 10 orders of magnitude (to a maximum conductivity of 101–102 S cm–1), forming a polysemiquinone radical cation such as [graphic omitted] which contains a delocalized half-filled broad polaron energy band. The polymer is readily solution-processed into films and fibres which can be mechanically aligned, the doped forms of which have a conductivity parallel to the direction of alignment significantly greater than that of non-aligned material. X-Ray studies show that the doped and undoped polymer exist in several different crystalline forms. A wide variety of derivatives can be synthesized by substitution on the ring or on the nitrogen.

973 citations

Journal ArticleDOI
TL;DR: The self-diffusion coefficient for pure liquid water has been measured at temperatures between 275.2 and 498.2 K and at pressures up to 1.75 kbar by the proton spin echo method as discussed by the authors.
Abstract: The self-diffusion coefficient, D, for pure liquid water has been measured at temperatures between 275.2 and 498.2 K and at pressures up to 1.75 kbar by the proton spin echo method. Our values of D agree, where they overlap, with recently published data which, however, were measured mostly at low temperature and over rather narrow ranges of temperature.The results are discussed in several ways. The Stokes–Einstein relation is found to be obeyed in the slipping boundary limit. The cubic cell model of Houghton accounts satisfactorily for the measured D values, particularly at higher temperatures. A simple test of a hard-sphere model is found to give poor agreement at lower temperatures but a modified hard-sphere theory seems to be more satisfactory. The activation analysis at constant density shows that water behaves very differently from non-associated liquids. It also suggests that an increase in both temperature and pressure leads to an increase in the fraction of free unbonded water molecules.A free-volume analysis has led to a modified Arrhenius equation which involves pressure-dependent terms. This semi-empirical equation describes the results within experimental error and predicts a glass temperature at 115 K which is in reasonable agreement with the values obtained by other methods.

676 citations

Journal ArticleDOI
TL;DR: In this article, the role of polarizability in determining the position of core-type Auger lines has been investigated and the Auger parameter has been shown to be accurately determinable to ± 0.1 eV.
Abstract: Earlier observations on the magnitudes of chemical shifts of photoelectron and core-type Auger lines, and the concept of the role of polarizability, have been combined to produce a unified concept of the role of polarization in determining line position. With core-type Auger lines, polarization effects are more important in determining chemical shifts than are changes in electron density on the atom in the ground state. A parameter, termed the Auger parameter, is proposed as a specific property of a chemical and physical state. It is accurately determinable to ±0.1 eV, and with most elements to which it is applicable the range among compounds is several eV. Differences in the Auger parameter are attributable solely to changes in the polarizability of the solid compounds.

653 citations

Journal ArticleDOI
TL;DR: In this paper, a semi-rigid model with fixed C-C bonds and angles was used for simulation of liquid systems of n-alkanes and the results of two different simulations of nbutane and of one simulation of ndecane were analyzed.
Abstract: The method of molecular dynamics is applied to the simulation of liquid systems of n-alkanes. The model used is a semi-rigid one with fixed C—C bonds and C—C—C angles. In addition to the static and dynamic properties usually deduced for monatomic fluids from such computer experiments, the configurational properties and the internal relaxation behaviour of the alkane chain are also studied. The results of two different simulations of n-butane and of one simulation of n-decane are analysed. The usefulness and the limitations of such computer experiments are discussed briefly.

615 citations

Journal ArticleDOI
TL;DR: In this article, the authors show that the mechanical strength of calcium alginate gels is mainly due to junctions formed by the GG-blocks, and that the modulus of rigidity of gels formed by different cations is directly dependent on their ability to bind to polyuronides by a cooperative inter-chain binding mechanism.
Abstract: Alginate is a binary linear heteropolymer containing 1,4-linked β-D-mannuronic and α-L-guluronic acid residues in varying proportions. The monomers are arranged in a blockwise fashion along the chain; it contains the two homopolymeric blocks (MM and GG) together with blocks of the alternating sequence (MG) in the same molecule. Data from light scattering and viscometric experiments show that their relative unperturbed dimensions increase in the order: MG-blocks < MM-blocks < GG-blocks. Ion exchange data show that GG-blocks are characterized by a selective binding of calcium ions in solution, a strong autocooperative binding of calcium between the chains in the gel state, and hystrisis due to a slow dissociation of the cooperatively-formed functions between the chains. The two other blocks have much lower selectivity for calcium ions, no autocooperative binding mechanism and no detectable hysteresis. The mechanical strength of calcium alginate gels is mainly due to junctions formed by the GG-blocks. the modulus of rigidity of gels formed by different cations is directly dependent on their ability to bind to the polyuronides by a cooperative inter-chain binding mechanism.

422 citations

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Performance
Metrics
No. of papers from the Journal in previous years
YearPapers
20191
20012
19981
19941
199125
199044