Stretching of DNA confined in nanochannels with charged walls

There is currently a growing interest in control of stretching of DNA inside nanoconfined regions due to the possibility to analyze and manipulate single biomolecules for applications such as DNA mapping and barcoding, which are based on stretching the DNA in a linear fashion. In the present work, we couple Finite Element Methods and Monte Carlo simulations in order to study the conformation of DNA molecules confined in nanofluidic channels with neutral and charged walls. We find that the electrostatic forces become more and more important when lowering the ionic strength of the solution. The influence of the nanochannel cross section geometry is also studied by evaluating the DNA elongation in square, rectangular, and triangular channels. We demonstrate that coupling electrostatically interacting walls with a triangular geometry is an efficient way to stretch DNA molecules at the scale of hundreds of nanometers. The paper reports experimental observations of λ-DNA molecules in poly(dimethylsiloxane) nanochannels filled with solutions of different ionic strength. The results are in good agreement with the theoretical predictions, confirming the crucial role of the electrostatic repulsion of the constraining walls on the molecule stretching.     

Towards a framework for creative online collaboration: A research on challenges and context

The OnCreate project was initiated by ten universities with expertise in collaborative work in online-based learning environments and explores the specific challenges of implementing university courses in creative disciplines in such an environment. The first research phase comprises a literature search on creativity and its contextual factors in online collaboration in an educational setting. From this research a first set of possible key challenges and contextual key factors has been selected and applied to categorize the results of interviews and surveys on current good practice in creative online collaboration among experienced online teachers from the partner universities. From the key findings we formulate hypotheses to guide future research towards a framework for creative online collaboration. At the same time, the results can serve as inspiration for the educational practice. Notable observations of the good practice research among the partner universities are that they realise innovative collaboration concepts usually on mashed-up environments of state-of-the-art web services rather than on the omnipresent learning management systems (such as Moodle or Blackboard). Also, they show a paradigm shift from teaching to coaching and promotion of an open peer-review culture among the students.