Novel probes for pH and dissolved oxygen measurements in cultivations from millilitre to benchtop scale

Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch)pH value and the concentration of dissolved oxygen (DO) are key parameters to monitor and control cell growth in cultivation studies. Reliable, robust and accurate methods to measure these parameters in cultivation systems in real time guarantee high product yield and quality. This mini-review summarises the current state of the art of pH and DO sensors that are applied to bioprocesses from millilitre to benchtop scale by means of a short introduction on measuring principles and selected applications. Special emphasis is placed on single-use bioreactors, which have been increasingly employed in bioprocess development and production in recent years. Working principles, applications and the particular requirements of sensors in these cultivation systems are given. In such processes, optical sensors for pH and DO are often preferred to electrochemical probes, as they allow semi-invasive measurements and can be miniaturised to micrometre scale or lower. In addition, selected measuring principles of novel sensing technologies for pH and DO are discussed. These include solid-state sensors and miniaturised devices that are not yet commercially available, but show promising characteristics for possible use in bioprocesses in the near future

Credit Rationing with Symmetric Information

Without denying the importance of asymmetric information, this article purports the view that credit rationing may also originate from a lender's inability to classify loan applicants in proper risk categories. This effect is particularly strong when novel technologies are involved. Furthermore, its relevance may increase with the importance assigned to internal rating systems by the Basel accord. This article presents a measure of the inadequacy of a lender's classification criteria to the qualitative features of prospective borrowers. Even without information asymmetries, credit rationing may occur if this quantity reaches too high a value. Furthermore, some general principles are outlined, that may be used by lenders in order to change their classification criteria