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January 2007

Properties of Water in Colloidal and Biological Systems
Dr. Carel Jan van Oss, an Adjunct Professor and Professor Emeritus at the University of Buffalo (NY), has long been a leading expert in the study of colloid and surface properties. He is the author of Interfacial Forces in Aqueous Media (now it it's second edition), and coauthor of Colloid and Surface Properties of Clays and Related MineralsMolecular Immunology: A Textbook, and editor of Immunochemistry. All of the above books I should mention are currently available on Amazon.com -- although there is a wait for most of them. He's written or co-written numerous other books and over 300 papers during his expansive career.

The second edition of Interfacial Forces in Aqueous Media (2006) focuses on the understanding of polar interfacial and non-covalent interactions on macromolecules, biopolymers, particles, solid homogenous surfaces, cells, and polar as well as apolar polymers. The second edition also contains four new chapters dealing with interfacial tension and the properties and structure of water. In particular, the kinetics and energetics of protein absorption on metal oxide are examined.

During the 1980's van Oss and others demonstrated how the contribution due to acid-base interactions can be expressed in terms of the product of their electron donor and electron acceptor components using a series of three liquids: one polar and two apolar. Water with either glycerol or formamide work well for the apolar components. The polar component might be methylene iodide or bromonaphtalene.

This method of measurement, referred to as the Acid-Base method, is available in both ramé-hart DROPimage Standard as well as DROPimage Advanced software. After a series of contact angle measurements are taken using the three liquids sets, the surface energy is then calculated by DROPimage using Monte Carlo simulation.

I had the opportunity to hear Dr. van Oss lecture this past summer in Toronto at the Fifth International Symposium on Contact Angle, Wettability, and Adhesion. In his lecture he detailed his discoveries relative to the little-understood physico-chemical properties of water and how these properties are the basis for the understanding of the polar interactions occurring in water. He explained his particular interest in the "hyper-hydrophobicity" of the water-air interface, the cluster formation of water molecules while in the liquid state, and the unusually high invariability of the ratio of the electron-accepticity to the electron-donicity of water in the liquid state as a function of temperature. This ratio is associated with the cluster size and contrasts with the typically defined polar cohesive energy which does not vary much with changes in temperature. These properties help us better characterize water as well as understand surface properties of ice and the water-ice-gas interfaces.

Carel Jan van Oss
(photo compliments of Univ. of Buffalo Reporter)

In September 2006 we featured Dr. van Oss in our Who's Who in Surface Science edition of this newsletter. There we detailed some of his other accomplishments. For example, prior to arriving in the United States, van Oss was a decorated WWII hero having assisted hundreds of Jews from Nazi invaders by forging documents on their behalf.

Product of the Month - Chamber Cover with Stage
If you are interested in performing liquid-liquid studies or simply require a controlled environment, you should look at or may already have the ramé-hart Environmental Chamber (p/n 100-07). This useful option allows for control over the temperature up to 300°C with the optional Proportional Temperature Controller (p/n 100-50). This chamber can be used with our Quartz Cell (p/n 100-07-50) which fits directly inside the chamber. We also offer a special Chamber Cover with Stage option (see image below, p/n 100-09-10).

Chamber Cover with Stage
(p/n 100-09-10)

This accessory will support sessile drops on the top side, inverted sessile drops on the underside and can be used in both gas and liquid phases. The product includes clamps on the stage for quick change of the solid phase. Films can also be used. The entire stage is adjustable in the Z-axis (up and down). The is a completely sealed quick-release lid for easy dispensing with either a manual syringe or our Automated Dispensing System. Both straight and inverted needles are supported. This option along with our Environmental Chamber is supported on our legacy Model 100-00 as well as our current software-based Models 300 and 500.

Should you have any questions regarding this product or the related Environmental Stage, please contact us for more information and a quotation.



Carl Clegg
Director of Sales
Phone 973-448-0305
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