New Types of Structures for Cage-Like Clathrates

Compounds Could Be Basis For Devices That Turn Waste Heat Into Electricity

Cage-like compounds called clathrates could be used for harvesting waste heat and turning it into electricity. UC Davis chemists just discovered a whole new class of clathrates, potentially opening new ways to make and apply these materials.

Journal cover image

UC Davis chemists discovered a new class of clathrates that break the four-bond rule. The discovery was featured on the cover of the journal Angewandte Chemie (Wiley)

UC Davis’ McClellan Nuclear Reactor, At 27 One of “Newest” in U.S.

By Lisa Howard

On January 20, 1990, when the nuclear reactor at McClellan Air Force Base achieved its first sustained nuclear reaction known as “criticality,” it was the newest reactor in the United States.

Six years later, when the Tennessee Valley Authority launched the Watts Bar Nuclear Generating Station, the nuclear reactor at McClellan was relegated to second newest. McClellan would go on to retain that ranking for another two decades until this past October when the Tennessee Valley Authority launched Watts Bar Unit 2.

Perovskite, Potential Solar Cell Material Unsuited for Real-World Use

By Becky Oskin

Solar cells made from perovskites have sparked great excitement in recent years because the crystalline compounds boast low production costs and high energy efficiencies. Now UC Davis scientists have found that some promising compounds — the hybrid lead halide perovskites — are chemically unstable and may be unsuited for solar cells.

“We have proven these materials are highly unlikely to function on your rooftop for years,” said Alexandra Navrotsky, interdisciplinary professor of ceramic, earth, and environmental materials chemistry at UC Davis and director of the Nanomaterials in the Environment, Agriculture, and Technology (NEAT) organized research unit.

Magneto-ionics could be a new alternative to electronics

Our electronic devices are based on what happens when different materials are layered together: “The interface is the device,” as Nobel laureate Herbert Kroemer famously claimed over 40 years ago. Right now, our microchips and memory devices are based on the movement of electrons across and near interfaces, usually of silicon, but with limitations of conventional electronics become apparent, researchers are looking at new ways to store or process information. These “heterostructures” can also find applications in advanced batteries and fuel cells.

Now physicists at UC Davis have observed what’s going on at some of these interfaces as oxygen ions react with different metals, causing drastic changes in magnetic and electronic properties.

Magnetic skyrmions at room temperature: New digital memory?

An exotic, swirling object with the sci-fi name of a “magnetic skyrmion” could be the future of nanoelectronics and memory storage. Physicists at UC Davis and the National Institute of Standards and Technology (NIST) have now succeeded in making magnetic skyrmions, formerly found at temperatures close to absolute zero, at room temperature.

“This is a potentially new way to store information, and the energy costs are expected to be extremely low,” said Kai Liu, professor of physics at UC Davis and corresponding author of a paper on the work, published in the journal Nature Communications Oct. 8.

UC Davis graduate student to attend Lindau Nobel Laureate meeting

By Derrick Bang

Christopher Chapman, a Ph.D. student in the UC Davis Department of Biomedical Engineering, has been selected to attend the 65th annual Lindau Nobel Laureate Meeting, taking place June 28-July 3 in Lindau, Germany. Chapman will join a U.S. delegation of roughly 55 “young researchers,” as they’re designated by the Lindau committee.

Christopher Chapman, a PhD student in the UC Davis Department of Biomedical Engineering

The U.S. delegation will be among the Lindau Meeting’s approximately 650 global student and postdoctoral researchers from all three natural science Nobel Prize disciplines: medicine and physiology, physics, and chemistry. They’ll meet and confer with the 65 Nobel Laureates who will gather to interact with this next generation of leading scientists and researchers.

UC Davis plans joint research with Brazil

FAPESP, the São Paulo Research Foundation and UC Davis announced May 12 the launch of a new program to strengthen collaborative research in physical sciences, engineering, biomedical sciences and agriculture within the framework of the cooperation agreement signed by the two institutions in 2012.

The announcement was made during the opening of FAPESP Week UC Davis in Brazil, a two-day event attended by 26 scientists from UC Davis and institutions in São Paulo State to present research findings in a range of knowledge areas. The event is a follow-up to FAPESP Week California, held in November 2014 at UC Davis and UC Berkeley in the United States.

Better measures of single molecule circuits

A hexane (six-carbon) molecule between two gold electrodes. A new UC Davis technique gives better measurements of these circuits. (Josh Hihath/UC Davis)

A hexane (six-carbon) molecule between two gold electrodes. A new UC Davis technique gives better measurements of these circuits. (Josh Hihath/UC Davis)

It’s nearly 50 years since Gordon Moore predicted that the density of transistors on an integrated circuit would double every two years. “Moore’s Law” has turned out to be a self-fulfilling prophecy that technologists pushed to meet, but to continue into the future, engineers will have to make radical changes to the structure or composition of circuits. One potential way to achieve this is to develop devices based on single-molecule connections.

Engineering self-assembling amyloid fibers

Nature has many examples of self-assembly, and bioengineers are interested in copying or manipulating these systems to create useful new materials or devices. Amyloid proteins, for example, can self-assemble into the tangled plaques associated with Alzheimer’s disease — but similar proteins can also form very useful materials, such as spider silk, or biofilms around living cells. Researchers at UC Davis and Rice University have now come up with methods to manipulate natural proteins so that they self-assemble into amyloid fibrils. The paper is published online by the journal ACS Nano.

New X-ray technique for surfaces

Surfaces are very interesting to material scientists. The reactions that happen at the point where inside and outside meet, and elements interact with other chemicals or radiation, are important for developing new technology for batteries, fuel cells or photovoltaic panels, for catalysts for the chemical industry, and for understanding environmental chemistry and pollution. Now researchers at UC Davis and the Advanced Light Source at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory have combined two existing methods techniques to come up with a new method for studying surfaces with X-rays. This new technique is called SWAPPS, for Standing Wave Ambient Pressure Photoelectron Spectroscopy.