Science at the Shine Dome 2010
Career research awards
Thursday, 6 May 2010
2010 David Craig Medal
Professor Robert G Gilbert FAA
Research Professor, Centre for Nutrition and Food Sciences
University of Queensland
Robert (Bob) Gilbert is research professor in the Centre for Nutrition and Food Science, University of Queensland. His research covers three fields: chemical reaction dynamics, the mechanisms of polymerisation, and biopolymer structure-property relations. He received his undergraduate training at Sydney University, graduating in 1966, and his PhD from the Australian National University, graduating in 1970. He carried out postdoctoral work at the Massachusetts Institute of Technology from 1970 to 1972, and then returned to the University of Sydney, where he held a personal chair in polymer chemistry and was director of the Key Centre for Polymer Colloids. In 2006, he took up a position in the Centre for Nutrition and Food Sciences at the University of Queensland to pursue his interests in the relations between the polymeric structure of starch and human nutrition.
Understanding mechanisms in complex chemical systems
Some chemical systems are extremely complex, and thus it is very hard to obtain unambiguous information on the underlying mechanisms. Modelling to reach agreement with experiment is no more than an exercise in curve-fitting, because there are many parameters whose values are uncertain, and thus there are many possible sets of values which can be found to agree with data; thus such modelling can never be used to refute a mechanistic hypothesis.
In my talk I will give three examples where a reductionist approach suggests new types of experiment to cut such Gordian knots, and which then enables novel types of data to be obtained and used to refute or support mechanistic hypotheses. When implemented, these experiments yield unambiguous mechanistic information on the mechanisms. 1. Gas-phase reactions, involving huge numbers of individual energy states, can be parameterised in terms of a few physically meaningful parameters. 2. Emulsion polymerisation, used to make a wide range of products such as paint and adhesives, is a complex multiphase process, but it can be broken down into only seven types of reactions; the right sort of experiments then show what mechanisms govern these reaction types. 3. Starch biosynthesis involves many enzymes, but these are only of three types. A reductionist approach is used to reveal a hitherto unsuspected simplicity, and also to reveal both limitations and targets for plant engineers aiming for starch-based plants with improved nutritional characteristics of importance for diabetes and obesity.
