Читать книгу Osmosis: The Molecular Theory - Larry Howlett - Страница 3

Osmosis is not a normal word or thought for engineers. Several interesting career situations led to a path where my skills were applied on basic engineering problems. One of these was a design and build seed storage warehouse. Beginning with an open slate for all parameters, we had the opportunity to research the literature for optimum seed storage environments and develop the equipment to maintain these conditions.

We noticed a control system problem and corrected it by using temperature and vapor pressure as control variables. The measured temperature and relative humidity were used to calculate the moisture vapor pressure using a simple algorithm.

This successful modification to the controls suggested that vapor pressure might be an important variable in defining seed storage. Others had introduced van’t Hoff’s theory of osmosis as an important factor in defining seed storage conditions. The magnitude of vapor pressure is insignificant compared to value of van’t Hoff’s osmotic pressure.

A conflict was thus established between the vapor pressure model and the osmotic pressure approach used by others. By the time that we discovered this conflict, we had already thoroughly tested our approach and had successful operating equipment.

Therefore, we studied osmosis. It was an intriguing problem. An experiment by J.A.Nollet in 1748 showed that water flowed uphill into wine. A large pressure had to be applied to the wine to stop the flow. After 150 years, van’t Hoff found the first thermodynamic explanation of the phenomena. But, van’t Hoff’s work has been challenged by many during the last 110 years.

Our initial paper on osmosis clearly incorporated van’t Hoff’s work into a complete theory for osmosis. Later papers provide thermodynamic support of the vapor pressure model and provide a new molecular understanding of solids, liquids, and vapor pressure. The chapters in this book are papers that we wrote to explain osmosis.

It has certainly been an interesting task. We are thankful to the many that have provided support during this process. Some of these are: Dr McGuay, Dr Kenny and Mr Sandstorm (Bradley University), and Dr WL Chow and Mr Hebrank (University of Illinois). We owe thanks to all whose direct or indirect efforts put us in position to look at the osmosis phenomena including Jeff Elwer (DeKalb Genetics), to family and friends especially my children Lori, David, Kathleen & their families. Grateful thanks to Jim Niewold, Dee Diehl, Denny O’Hara,Dick Moudy, Sandy Talley and Ella Benzinger who brought support at special times during and through this process.