A Diplomat’s Reminiscences

Book Revie

Understanding and harnessing entropy in colloids

I will discuss what we have learned about entropy from experiments on micrometer-scale colloidal particles, which can be seen under an optical microscope. From experiments on small colloidal systems (clusters of interacting spherical particles), we find that entropy has a complex relationship with order and symmetry, but one that can be understood within a simple framework—so long as we allow that entropy is a measure of the number of states that we as observers choose not to distinguish, rather than of those that are fundamentally indistinguishable. I will then show how a better understanding of entropy allows us to design new materials and nanomachines

RNA Folding and Hydrolysis Terms Explain ATP Independence of RNA Interference in Human Systems

Although RNA interference (RNAi) has emerged as an important tool for studying the effects of gene knockdown, it is still difficult to predict the success of RNAi effectors in human systems. By examining the basic thermodynamic equations for RNA interactions in RNAi, we demonstrate how the free energies of RNA folding and phosphoester bond hydrolysis can drive RNAi without ATP. Our calculations of RNAi efficiency are close to actual values obtained from in vitro experimental data from 2 previous studies, for both silencing complex formation (2.50 vs. 2.40 for relative efficiency of RISC formation) and mRNA cleavage (0.50 vs. 0.56 for proportion cleaved). Our calculations are also in agreement with previous observations that duplex unwinding and target site folding are major energy barriers to RNAi.Engineering and Applied SciencesPhysic