Smith,Wilson

Several types of impingers are used in different laboratories throughout the world. Some of them are named according to particular workers, such as the Polezhaev, Greenburg-Smith, Wilson and Zaitsev impingers [3, 4]. 

Wilson M R, Allen M P, Warren M A, Sauron A and Smith W 1997 Replicated data and domain decomposition molecular dynamics techniques for the simulation of anisotropic potentials J. Comput. Chem. 18 478-88... 

MR Wilson, MP Allen, MA WaiTen, A Sauron, W Smith. J Comput Chem 18 478-488, 1997. 

In spite of the interest displayed in recent years in the natural distribution and the chemistry of anagyrine very little work has been done on its pharmacology as Smith and Wilson have pointed out its vasoconstrictive action has been investigated by Tournade and Raymond-Hamet. ... 

A. Wilson, G. E., How to select bottom-hole drilling assemblies, Part I, Publ. No. 62, Drilco, Division of Smith International, Inc., Houston, 19XX. 

Synthesis of Uronic Acids. Part II. 2 3 4-Trimethyl Derivatives of Mannuronic, Glucuronic, and Galacturonic Acids, F. Smith, M. Stacey, and P. I. Wilson, J. Chem. Soc., (1944) 131-134. 

Allen MP, Warren MA, Wilson MR, Sauron A, Smith W (1996) J Chem Phys 105 2850 Allen MP (1990 ) Phys Rev Lett 65 2881... 

Silver RB, Mackins CJ, Smith NCE, Koritchneva IL, Lefkowitz K, Lovenberg TW> Levi R Coupling of histamine H3 receptors to neuronal Na+/H+ exchange a novel protective mechanism in myocardial ischemia, Proc Natl Acad Sci USA 2001 98 2855. Silver RB, Poonwasi KS, Seyedi N, Wilson SJ, Lovenberg TW, Levi R Decreased intracellular calcium mediates the histamine H3-receptor-induced attenuation of norepinephrine exocytosis from cardiac sympathetic nerve endings. Proc Natl Acad Sci USA 2002 99 501. 

Wilson BH, Smith GB, Rees JF. 1986. Biotransformations of seleeted alkylbenzenes and halogenated aliphatie hydrocarbons in methanogenic aquifer material A microcosm study. Environmental Science and Technology 20 997-1002. 

The reaction between peroxysulphuric acid and thiocyanate ions was investigated by Smith and Wilson by a stopped-flow conductance method. Their results can be summarized as follows. If / and m are the numbers of moles of cyanate and sulphur dicyanide produced per mole of thiocyanate consumed, the overall stoichiometric equation is... 

In the 1870s more effective liquid cement-formers were found ortho-phosphoric acid and eugenol (Wilson, 1978). It was also found that an aluminosilicate glass could replace zinc oxide, a discovery which led to the first translucent cement. Thereafter the subject stagnated until the late 1960s when the polyelectrolyte cements were discovered by Smith (1968) and Wilson Kent (1971). 

Polyelectrolytes are polymers having a multiplicity of ionizable groups. In solution, they dissociate into polyions (or macroions) and small ions of the opposite charge, known as counterions. The polyelectrolytes of interest in this book are those where the polyion is an anion and the counterions are cations. Some typical anionic polyelectrolytes are depicted in Figure 4.1. Of principal interest are the homopolymers of acrylic acid and its copolymers with e.g. itaconic and maleic adds. These are used in the zinc polycarboxylate cement of Smith (1968) and the glass-ionomer cement of Wilson Kent (1971). More recently, Wilson Ellis (1989) and Ellis Wilson (1990) have described cements based on polyphosphonic adds. 

The most common poly(alkenoic acid) used in polyalkenoate, ionomer or polycarboxylate cements is poly(acrylic acid), PAA. In addition, copolymers of acrylic acid with other alkenoic acids - maleic and itaconic and 3-butene 1,2,3-tricarboxylic acid - may be employed (Crisp Wilson, 1974c, 1977 Crisp et al, 1980). These polyacids are prepared by free-radical polymerization in aqueous solution using ammonium persulphate as the initiator and propan-2-ol (isopropyl alcohol) as the chain transfer agent (Smith, 1969). The concentration of poly(alkenoic add) is kept below 25 % to avoid the danger of explosion. After polymerization the solution is concentrated to 40-50 % for use. 

Many divalent and trivalent oxides form cements with PAA (Crisp, Prosser Wilson, 1976 Hodd Reader, 1976 Hornsby, 1977). Cement formation was observed using infrared spectroscopy and physical and chemical tests. Of these cements that of ZnO (Smith, 1968) was the first and remains by far the most important it is given detailed treatment in Section 5.7. 

The liquid is usually a 30-43 % solution of a poly(alkenoic add) which is a homopolymer of acrylic acid or a copolymer with itaconic acid, maleic add, or 3-butene 1,2,3-tricarboxylic add (Smith, 1969 Bertenshaw Combe, 1972a Jurecic, 1973 ESPE, 1975 Wilson, 1975b Suzaki, 1976 Crisp, Lewis Wilson, 1976a Crisp Wilson, 1974c, 1977 Crisp et al., 1980). The method of preparation has already been given in Section 5.3, and the structures of these alkenoic add units are shown in Figure 5.1. The molecular mass of these polyadds varies from 22000 to 49000... 

X-ray diffraction shows that both the cement matrix and the salt are amorphous (Wilson, 1982 Smith, 1971 Steinke et al., 1988). On the basis of chemical analysis, Wilson (1982) assigned the following empirical formula to the zinc polyacrylate salt ... 

Scanning electron microscopy shows the cement to consist of zinc oxide particles embedded in an amorphous matrix (Smith, 1982a). As with the zinc phosphate cement, a separate globular water phase exists since the cement becomes uniformly porous on dehydration. Porosity diminishes as the water content is decreased. Wilson, Paddon Crisp (1979) distinguish between two types of water in dental cements non-evaporable (tightly bound) and evaporable (loosely bound). They found, in the example they examined, that the ratio of tightly bound to loosely bound water was 0-22 1-0, the lowest for all dental cements. They considered that loosely bound water acted as a plasticizer and weakened the cement. 

The solubility of these cements in water (when aged from one to 24 hours) is small and ranges from 01 to 06% (Gourley Rose, 1972 Bertenshaw, Combe Grant, 1979 Crisp, Lewis Wilson, 1976a Smith,... 

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