New X-ray Spectroscopy Explores Hydrogen-generating Catalyst

Using a newly developed technique, researchers from Japan, Germany and the U.S. have identified a key step in production of hydrogen gas by a bacterial enzyme. Understanding these reactions could be important in developing a clean-fuel economy powered by hydrogen.

The single-celled green alga Chlamydomonas reinhardtii has an iron-based enzyme that can generate hydrogen gas. (JGI)

The team studied hydrogenases – enzymes that catalyze production of hydrogen from two widely distributed organisms: Chlamydomonas reinhardtii, a single-cell algae and Desulfovibrio desulfuricans, a bacterium.

In both cases, their hydrogenase enzymes have an active site with two iron atoms.

Microbes Could Bring Tea to California

Key to Tea’s Benefits May Be in the Soil

By Becky Oskin

Tea has long been linked to human health benefits like preventing cancer and heart disease. But with hundreds of chemical compounds hidden in tea leaves, it is unclear which substances have the strongest effects.

The slew of “healthy” chemicals in tea varies with the variety of plant, how and where it is grown, and how the leaves are processed. Even soil bacteria contribute to a plant’s chemical profile, including its color, taste and aroma.

Podcast: Melting Ice and the Quasi Liquid Layer

Water ice is peculiar stuff: Even below freezing, when it should be solid, it has a quasi-liquid layer on the outside. That’s what makes ice slippery. In this month’s Three Minute Egghead podcast, UC Davis chemist Davide Donadio describes his recent research looking at the surface of ice and what it has to do with clouds and air pollution.

https://soundcloud.com/andy-fell/melting-ice

Computer simulation of ice

Computer simulation of the surface of ice shows how layers melt in steps (Credit: Davide Donadio)

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Related news story: Ice Surface Melts One Step at a Time

Refining the Ocean’s Thermometer

By Becky Oskin

Chronicling Earth’s past temperature swings is a basic part of understanding climate change. One of the best records of past ocean temperatures can be found in the shells of marine creatures called foraminifera.

The foraminiferan Neogloboquadrina dutertrei forms a record of ocean conditions as it builds its shell. Photo by J. Fehrenbacher

Known as “forams” for short, these single-celled plankton build microscopic calcite shells. When forams die, their shells fall to the ocean floor and accumulate in sediments that provide a record of past climate. The surface-feeding plankton are natural thermometers because the chemical makeup of foram shells is linked to the environmental conditions they grow in. For example, the levels of magnesium in foram shells reflect the seawater temperature in which they lived.

Clues to Life on Mars in a Polluted California Mine

By Becky Oskin

To find evidence of life on Mars, scientists from UC Davis and the U.S. Geological Survey are chasing clues in Mars-like environments on Earth.

Pollution at the disused Iron Mountain mine near Redding, Calif. turns the soil red and makes the environment Mars-like. Amy Williams, Towson University

The environment at the Iron Mountain mine near Redding, Calif. is similar to Mars. Amy Williams, Towson University

The researchers hope to find rock patterns and textures that are uniquely linked to microscopic life such as bacteria and algae. “It’s challenging to prove that a mineral was made by a living organism,” said lead study author Amy Williams, an assistant professor at Towson University in Towson, Maryland. Williams led the research as a graduate student at UC Davis. Finding similar textures in Mars rocks could bolster confidence that microscopic shapes in Red Planet rocks were formed by living creatures.

UC Davis Scientists Boost Production in Green Cell Factories

By Becky Oskin

Cyanobacteria, one of Earth’s oldest life forms, offer a promising new source of petroleum-free fuels and chemicals. However, economies of scale currently make it challenging for these tiny creatures to compete with fossil fuels. Now, scientists at UC Davis are closer to meeting these challenges with a new advance that improves the production and growth rate of cyanobacteria.

Cyanobacteria culture

UC Davis chemist Shota Atsumi is engineering these cyanobacteria to produce biofuels. (Photo by T.J. Ushing)

Visiting scholar Masahiro Kanno, graduate student Austin Carroll and chemistry professor Shota Atsumi introduced new genetic pathways into cyanobacteria that could help make microbe-based chemical production systems smaller and easier to operate.

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)

Grounds For Concern: Is Your Coffee Consistent?

UC Davis entomologist Christian Nansen trained some high-tech analysis on coffee beans, showing that brands were not consistent in content. Photo: Kathy Garvey

UC Davis entomologist Christian Nansen trained some high-tech analysis on coffee beans, showing that brands were not consistent in content. Photo: Kathy Garvey

By Kathy Keatley Garvey

If your particular brand of coffee doesn’t seem to taste the same from week to week or month to month, you may be  right. And it’s not you, it’s the coffee beans.

Agricultural entomologist Christian Nansen of the UC Davis Department of Entomology and Nematology and four colleagues analyzed 15 brands of roasted coffee beans, purchased at an area supermarket on two dates about six months apart, and using hyperspectral imaging technology, found “they were all over the board.”

Chemwiki free textbook effort expands with $600,000 grant

By Becky Oskin

College students in the STEM fields could see sizable savings thanks to a $600,000 grant awarded to an open source textbook project developed at the University of California, Davis.

The ChemWiki project recently received $600,000 from the National Science Foundation to support further expansion of its open source textbooks into fields including statistics, math, geology, physics, biology and solar energy.

Digital course materials are steadily climbing in use in response to textbook cost concerns, according to an annual survey released in July by the National Association of College Stores. In August, the University of Maryland announced plans to completely eliminate print textbooks this academic year.

Oxygen oasis in Antarctic lake reflects distant past

At the bottom of a frigid Antarctic lake, a thin layer of green slime is generating a little oasis of oxygen, a team including UC Davis researchers has found. It’s the first modern replica discovered of conditions on Earth two and a half billion years ago, before oxygen became common in the atmosphere. The discovery is reported in a paper in the journal Geology.

The switch from a planet with very little available oxygen to one with an atmosphere much like today’s was one of the major events in Earth’s history, and it was all because some bacteria evolved the ability to photosynthesize. By about 2.4 billion years ago, geochemical records show that oxygen was present all the way to the upper atmosphere, as ozone.