学 术 报 告 1

报告题目：How bacteria eat minerals?

报告人：Miao Chen

时间：2015年4月7日星期二 下午2:30-3:30

地点：物电学院报告厅

报 告 摘 要

The needs for non-renewable metal resources keep increasing, and at the same time we are facing the challenge of minimizing the environmental impact of mining them. One possible approach is to use microbes to help extract valuable metals from low-grade ores with minimal energy and material wastage, in a process called bioleaching. Advanced technologies from electrochemistry, surface chemistry and materials characterization have been developed and employed to investigate the interactions between microbes and minerals in situ to gain a detailed understanding of the chemical and biochemical reaction mechanisms operating in bioleaching. Continuous real-time information on leaching solution is critical to understand both point source and non-point source impacts. For this purpose, robust, sensitive chemical sensors have been developed to make continuous, periodic or event-driven measurements without the need for frequent human intervention into this process which is taking place under extreme conditions.  

学 术 报 告 2

报告题目：Learning about thin liquid films and interfaces from  surface force measurements

报告人：Roger Horn

时间：2015年4月7日星期二 下午3：30-4:30

地点：物电学院报告厅

 报 告 摘 要

There are physical forces that act between surfaces when they are separated by distances of ~1 – 100 nm. These forces have their origin in intermolecular forces, and they depend strongly on the medium (liquid or gas) that is between the surfaces. Surface forces play a vital role in many practical systems, for example in particle suspensions, emulsions, foams, surface coatings, friction and lubrication, mineral flotation, etc. They also depend on the physico-chemical properties of the surfaces, which means that the forces can be controlled to some extent by modifying the surface chemistry and/or the properties of a liquid medium.

Conversely, by measuring the forces that act between surfaces as a function of the surface separation, we can learn about the properties of the surfaces. We can also investigate structural and dynamic properties of liquids in thin films between surfaces, right down to the molecular scale. After describing a classic instrument designed to make these measurements (the surface forces apparatus, SFA) I will present some older results that illustrate properties of thin liquid films confined between two solid surfaces. Then I will describe some measurements showing how the interface between two immiscible liquids behaves when a drop approaches a solid. Finally I will present recent results on air bubbles approaching a solid. These results show that the properties of the water-air interface are surprisingly complicated.