Remarks About Future Research Needs

Because one mole of calcite reacts with one mole of quartz, the molar reaction rates of phase A and B are identical, which equals the molar growth rate of wollastonite (D). Therefore, the linear reaction rate and u are related as follows  

Suppose the grain size for phase A is very small, leading to very large total surface area for reaction. That is, A A . Then (w - 1) (w - 1), meaning the fluid composition is such that it is very close to the saturation composition of phase A, whereas phase B is significantly undersaturated. After solving for vA and w , the reaction rate of A and B can be calculated if lA and are known. 

Experimental investigations will continue to play a critical role in understanding heterogeneous reaction kinetics, such as mineral dissolution rates in silicate melts and in aqueous solutions, the melting rates at the interfaces of two 

3 This question is about heterogeneous nucleation of orthopyroxene on olivine-melt interface in a basaltic melt. Suppose Oopx/meit = 0-35 J/m, Ooiiv/meit = 0-3 J/m, and Ooiiv/opx = 0-05 J/m. Find the contact angle and the modified interface energy o.  

4 The following are experimental data for diopside melting in its own melt (Kuo and Kirkpatrick, 1985). Diopside melting temperature is 1664 K. The fusion entropy is 82.76 J moC K Assume that the activation energy is 300 kj/mol. 

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Twenty-three years have elapsed since the American Chemical Society published a book devoted to papers from a symposium exclusively about lignin. In the preface to Lignin Structure and Reactions (Advances in Chemistry Series 59, 1966), the symposium chairperson remarked that the current presentation of lignin structure is oversimplified.. . . more ingenious work is needed to establish the sequence of units—the most prominent singular task of future lignin research. Presumably, the author of these words had in mind the sequence of intermonomer linkages rather than the units themselves (which differ only in their aromatic methoxyl substitution pattern), and from this perspective his observation could be as true in 1989 as it was in 1966. 

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