Title: In-situ measurements of catalysts using TOF neutron powder diffraction

Abstract:

Three elements commonly found in metal oxide alkene oxidation catalysts are molybdenum, bismuth and iron. In the case of ammoxidation of propylene to acrylonitrile many catalysts have ferric molybdate and a mixture of bismuth molybdates present in the as-prepared formulations. It is generally recognized that during catalyst activation ferric molybdate is reduced to Fe+2 phases, freeing molybdenum oxide for the formation of other phases. It is suspected, but has never been demonstrated, that this excess MoO3 then reacts with the bismuth containing phase(s) to form the active catalyst phase. Although this reaction is generally believed to occur in a number of catalytic processes the mechanism of the reaction has never been extensively studied. Due to the ease of in-situ measurements and the sensitivity to oxygen in the presence of heavy metals neutron diffraction is an ideal probe to study this reaction mechanism. We have developed a reaction cell that can be used in the General Purpose Powder Diffractometer at Intense Pulsed Neutron Source (IPNS), Argonne National Laboratory (ANL) for time resolved in situ study. Recent upgrades to GPPD, which have increased data rates by a factor of 6, now make these measurements possible. After an introduction of the Time of Flight (TOF) Neutron Scattering technique, preliminary findings about the evolution of a model oxidation catalyst under reaction conditions will be presented in this talk.

Title: Splicing messenger RNA

Abstract:

Messenger RNA is severly edited by our cells; only about 10% of a pre-mRNA is translated into a protein, the other 90% gets tossed away. I will describe two methods for identifying the splice junctions, a thermodynamic theory and a statistics theory incorporating ideas from scaling.

Abstract:

Neurons that command the eyes to move generate action potentials, or "fire," at a rate that is proportional to eye velocity. To maintain the eyes at a fixed position, motor neurons that control the muscles of the eye fire at a rate that is proportional to eye position; in the absence of their firing, spring-like forces return the eyes to the center of the head. The transformation of velocity-coded eye movement commands to position-coded firing of motor neurons is accomplished by an area of the brain known as the oculomotor neural integrator. In this talk, I will describe the experimental characterization of the goldfish neural integrator, mathematical models of the neuronal mechanisms that enable the velocity-to-position integration to be performed, and connections between neural integration and the storage of short-term memories.