Stanford Synchrotron Radiation Lightsource

Many practical catalysts, illustrated by those used for fossil fuel conversion and vehicle exhaust clean-up, consist of expensive noble metals dispersed on high-area porous solid supports. When the metals are atomically dispersed and isolated from each other, they offer new properties and the highest efficiency of metal use—with each metal atom accessible to reacting molecules. But applications of supported noble metal catalysts are usually limited by the loss of accessibility of reactants to the metals that results from metal aggregation (sintering) during operation. Sintering can be suppressed by anchoring the metal atoms strongly to metal oxide supports, but strong metal–oxygen interactions often leave too few metal sites available for reactant binding and catalysis.

An unconventional new class of superconducting materials discovered 35 years ago was met with much excitement.  These materials, known as copper oxides or cuprates, conducted electricity with no resistance or loss when chilled below a certain point – but at much higher temperatures than scientists had thought possible. This raised hopes of getting them to work at close to room temperature for perfectly efficient power lines and other uses. Research quickly confirmed that they showed two more classic traits of the transition to a superconducting state: As superconductivity developed, the material expelled magnetic fields, so that a magnet placed on a chunk of the material would levitate above the surface. And its heat capacity – the amount of heat needed to raise their temperature by a given amount – showed a distinctive anomaly at the transition. Despite decades of effort with a variety of experimental tools, the fourth signature, which can be seen only on a microscopic scale, remained elusive.

In the ongoing quest for a room-temperature superconductor, scientists are examining the normal, or ground, state of the highest temperature superconductors currently known. It is thought that understanding the particularities of the normal state in these materials, for example the mysterious pseudogap phase, would give clues to how to engineer materials that can lead to superconducting behavior at even higher temperatures. When studying the normal state, especially its ground state, the superconducting state needs to be quenched; otherwise it will interfere. Two established methods for quenching the superconducting state are applying an external magnetic field and using an optical pump, but the relationship between the states achieved by these two methods is unclear.

Polyketides are a diverse and important category of molecules with various functions including antibiotic, immunosuppressant, and antitumor. Some polyketides have great medical and economic value. One type of polyketide synthase (PKS), the enzymes that make polyketides, is called type I modular PKS.