LAARS study

The temp. coeS. of the eq. conductivity of sodium carbonate soln. for the mean temp. 22° is 00265 and for potassium carbonate, 0-0249. H. C. Jones and A. P. West, and C. Deguisne have also studied the temp, coeff. of the conductivity of these salts. M. H. van Laar studied the formation of sodium hydroxide by the electrolysis of soln. of sodium carbonate with and without the addition of an oxy-salt. W. Bien calculates the transport number for the anion in 0 052V-soln. at 23° to be 0 590, but as in the case of lithium carbonate hydrolysis interferes with the... 

Pindolol. In a controlled study comparing pindolol with methylphenidate treatment, 32 ADHD children (ages 7-13 years) had modest improvement in CD and ADHD however, side effects were problematic (Buite-laar et al., 1996). 

A number of SSRIs and SNRIs were tested for their effects on cognitive function in repeated-dose studies in healthy, non-depressed volunteers. Studies with SSRIs before 1999 have been reviewed by Lane and O Hanlon (1999) and some more recent reports deal with nefazodone. paroxetine and sertraline (Furlan et al., 2001 Schmitt et al., 2001 van Laar et al.. 2002). However, considering the populations studied in these trials (non-depressed subjects), the duration of drug administration (1 2 weeks) and the mostly low drug doses used, the relevance of these studies for a clinical situation may be questioned. 

Hustinx, W.N.M., van de Laar, R.T.H., van Huffelen, A.C., Verwey, J.C., Meulenbelt, J. Savelkoul, T.J.F. (1993) Systemic effects of inhalational methyl bromide poisoning a study of nine cases occupationally exposed due to inadvertent spread during fumigation. Br. J. ind. Med., 50, 155-159... 

William Prout (1785-1850) and his pioneering attempts to understand the nature of matter60 have been studied, as has Ladislaus Farkas (1904-1948) role in the establishment of physical chemistry in Israel.61 Some protagonists of physical chemistry in The Netherlands, J. H. Van t Hoff62 and Johannes van Laar (1860-1938),63 have been investigated, as has Johannes Diderik van der Waals (1837-1923) and his contributions to molecular science.64 Van t Hoff s decisive role in the development of chemical thermodynamics has also been examined.65... 

Most of the recent theories of liquid solution behavior have been based on well-defined thermodynamic or statistical mechanical assumptions, so that the parameters that appear can be related to the molecular properties of the species in the mixture, and the resulting models have some predictive ability. Although a detailed study of the more fundamental approaches to liquid solution theory is beyond the scope of this book, we consider two examples here the theory of van Laar, which leads to regular solution theory and the UNIFAC group contribution model, which is based on the UNIQUAC model introduced in the previous section. Both regular solution theory and the UNIFAC model are useful for estimating solution behavior in the absence of experimental data. However, neither one is considered sufficiently accurate for the design of a chemical process. 

Since the preparation of acetylacetone and similar /J-dicarbonyl compounds in the latter half of the nineteenth century, organic chemists have had considerable interest in their properties and reactions. The best known phenomenon of -dicarbonyls is their participation in tautomeric equilibria where an apparently pure compound is actually a mixture of two substances having keto and enol structures. Early studies with / -dicarbonyls revealed that these compounds exhibited chemical properties indicative of both the dicarbonyl and unsaturated hydroxy ketone structures. In an unsuccessful attempt to explain this anomalous behavior Laar (7) in 1885 coined the word tautomerism" which has survived to the present. By the turn of the century it was generally held that the dichotomous properties of -dicarbonyls resulted from the pure compound existing as a mixture of both keto and enol tautomers. Since... 

Guisan JM, Fernandez-Lafuente R, Rodriguez V et al. (1993) Enzyme stabilization by multipoint covalent attachment to activated preexisting supports. In van den Tweel WJJ, Harder A, Buite-laar RM (eds). Stability and stabilization of enzymes, vol. 47. Elsevier, Amsterdam, pp 55-62 Henderson I, Garcia-Junceda E, Liu KK et al. (1994) Qoning, overexpression and isolation of the type II FDP aldolase firom E. coli for specificity study and synthetic application. Bioorg Med Chem 2 837-843... 

As already introduced in Section 3.3.2, it is always advisable to first calculate the ideal solubility curve from the melting data of a substance using the simplified Schroder-van Laar equation (Equation 3.8). The presentation of the ideal values together with a couple of measured solubilities in a van t Hoff plot (Figures 3.18 and 3.20) is a reasonable way to evaluate the solubility behavior of a substance. Deviations between the ideal and real curves slopes e.g. indicate differences between the heat of melting and the heat of solution. Kinks occurring in the van t Hoff plot are an indication of various soHd phases of the substance present. Furthermore, a reasonable linearity of the plot allows extraction of solubility data in the temperature range studied. 

Meek IL, Vonkeman HE, Kasemier J, Movig KL, van de Laar MA. Interference of NSAIDs with the thrombocyte inhibitory effect of aspirin a placebo-controUed, ex vivo, serial placebo-controUed serial crossover study. Eur J CUn Pharmacol March 2013 69(3) 365-71. 

We can see that the regular solution model does not give us the variations of the activity coefficient with the amounts of substance. In fact, it is a family of models which includes several possible subsets - each one defined by a relation 9tj(x). We shall come across two of these subsets in our study the Van Laar equation (see Table 3.3) and the Hildebrand-strictly-regular solution model, which we shall touch on. 

This model, which yields excellent results for polar and non-polar molecular liquids, is especially well suited for the study of liquid/ vapor equilibrium and the equilibrium between two liquids that are not completely miscible. Regardless of the number of components of the solution, the application of this model only requires the knowledge of two adjustment parameters per binary system, which can be deduced from the solution. The model is so widely applicable that it actually contains a number of previously classic models such as the models put forward by Van Laar, Wilson, Renon et al. (the NRTL - Non Random Two Liquids -model), Scatchard and Hildebrand, Flory and Huggins as special cases. In addition, it lends a physical meaning to the first three coefficients P, 5 and , in the Margules expansion (equation [2.1]). 

Bussmann JBJ, van De Laar YM, Neelman MP et al. (1998) Ambulatory accelerometry to quantify motor behavior in patients after failed back surgery a validation study. Pain 74(2-3) 153-161. 

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