Integrated Calendar

The application of enzymes to solve important problems has evolved over hundreds of years but has still not yet reached its fullest potential. The activity of enzymes in their natural state, in their ideal environment, and with their natural substrates is often much greater than needed ex vivo, thus driving intense research in activity enhancement. The inability to reach highly effective catalytic rates in harsh environments and against unnatural substrates has led to a number of elegant methods to modify enzyme structure and function. Lessons learned from molecular genetics, adaptation to organic solvents, immobilization, and conjugation with small molecules and polymers have greatly increased the activity of enzymes outside of their natural environments. For some applications, current protein engineering technologies have resulted in highly productive reagents. For many other applications, optimized solutions have been elusive. An evolution of our understanding of enzyme immobilization and polymer-protein conjugation has led to the emergence of polymer-based protein engineering (PBPE). We have developed and applied techniques that allow us to design and synthesize polymers directly from the protein surface. The process allows us to saturate conjugation sites, and by growing the polymers using atom transfer radical polymerization (ATRP), to control polymer size and structure. PBPE thus offers an attractive method to predictably modify and enhance enzyme structure and function. Using polymers that respond to stimuli such as temperature and pH, enzyme activity and stability can be predictably modified without a dependence on molecular biology. We have demonstrated that temperature responsive enzyme-polymer conjugates show increased stability while retaining bioactivity and substrate affinity. We are currently working on specific modifications of a number of proteins for a wide variety of uses such as oral therapeutics, biofuel cells, molecular sieves, proteomic applications, and agent decontamination.

A hundred years ago Arnold Sommerfeld (1868-1951) extended Bohr's atomic model. The Bohr-Sommerfeld atom paved the way for quantum mechanics. Sommerfeld's institute at Munich University became a center of modern theoretical physics where quantum pioneers like Wolfgang Pauli, Werner Heisenberg, Hans Bethe and others began their career.

In my presentation I sketch Sommerfeld's own career with the focus on his quantum contributions. The extension of Bohr's model resulted in a theory of the fine structure (Sommerfeld's fine-structure constant) and turned the analysis of spectral lines into a new science. Sommerfeld's textbook Atomic Structure and Spectral Lines was regarded as the "bible“ from which the first generation of quantum physicists learned their craft.

I hope to provide insight into the mechanisms at work in the decade between the extension of Bohr's theory and the birth of quantum mechanics

Polaritons in 2D semiconductor microcavities have been a unique manybody system that demonstrates non-equilibrium quantum orders. To go beyond 2D condensation physics, it becomes important to control the fundamental properties of polaritons without destroying the quantum orders. I will discuss a unconventional microcavity system we make. It incorporates a slab photonic crystal as one of the cavity mirrors to confine, control and coupling polaritons in a non-destructive and scalable manner. We showed that strong-coupling can be established in the new cavity system, fundamental properties of the polaritons can be controlled by design, including the polarization, energy-momentum dispersion, and dimensionality. Coupled polariton systems are readily created. We also showed single-mode polariton lasing in a 0D cavity, which, unlike (quasi) 2D polariton lasers demonstrated in the past, featured Poisson intensity noise expected of a coherent state and strong condensate interactions manifested in Gaussian line-broadening of the polariton laser. Such a 0D polariton lasers provides a building block for coupled polariton lattices with designable fundamental properties. It may open a door to experimental implementation of coupled cavity quantum electrodynamics systems and quantum technologies based on manybody quantum fluids.