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Category: chemistry – Page 409

A Gecko-Inspired, Wall-Climbing Tank Bot

Circa 2011

Gravity is no obstacle for this climbing robot. It scales vertical walls—even those made of smooth materials like glass. Jeff Krahn, an engineer from Simon Fraser University in British Columbia, created this gecko-inspired tank of a robot, which he detailed in a paper in the journal Smart Materials and Structures this week.

Like a gecko, which can hang on to sheer glass with just one toe, the climbing bot uses what physicists call Van der Waals forces to stick to the wall. Its tanklike tracks are covered in a dry adhesive, a polymer resembling silicon that allows adhesion without chemicals or added energy. The molecules that make up this substance are temporary dipoles; they have a positively charged side and a negatively charged side. The charged sides of the molecules are attracted to their corresponding opposites on the wall the robot is climbing: negative to positive, positive to negative. Given enough surface area for these attractions to take place, Van der Waals forces can keep a pretty substantial weight stuck to a vertical wall. The climbing bot, for example, weighs in at half a pound.

To boost the climbing bot’s stickiness, Krahn needed to increase the surface area of its tracks, which allows more molecular interactions. So the tracks are covered with small bumps shaped like mushroom caps, each about the size of a human red blood cell. These bumps also allow the bot to cling to microscopic bumps and cracks in the surface of whatever it’s climbing. However, Krahn’s creation can’t scale a surface that’s too rough; the texture of concrete, for example, wouldn’t provide enough surface area for its tracks to get the proper grip, Krahn says.

Researchers advance fuel cell technology

Washington State University researchers have made a key advance in solid oxide fuel cells (SOFCs) that could make the highly energy-efficient and low-polluting technology a more viable alternative to gasoline combustion engines for powering cars.

Led by Ph.D. graduate Qusay Bkour and Professor Su Ha in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering, the researchers have developed a unique and inexpensive nanoparticle catalyst that allows the to convert logistic liquid fuels such as gasoline to electricity without stalling out during the electrochemical process. The research, featured in the journal, Applied Catalysis B: Environmental, could result in highly efficient gasoline-powered cars that produce low carbon dioxide emissions that contribute to global warming.

“People are very concerned about energy, the environment, and global warming,” said Bkour. “I’m very excited because we can have a solution to the energy problem that also reduces the emissions that cause global warming.”

Humans Might Be So Sickly Because We Evolved to Avoid a Single Devastating Disease

Hundreds of thousands of years ago, our ancestors evolved a simple trick that could have helped thwart a major infectious disease. It probably saved our skins, but the change was far from a perfect solution.

New research has uncovered evidence that mutations arising between 600,000 and 2 million years ago were part of a complex of adaptations that may have inadvertently made us prone to inflammatory diseases and even other pathogens.

An international team of researchers compared around a thousand human genomes with a few from our extinct cousins, the Neanderthals and Denisovans, to fill in missing details on the evolution of a family of chemicals that coat the human body’s cells.

Origin of Stonehenge megaliths identified

A centuries-old question surrounding Stonehenge has been solved, linking the tall megaliths to a geographic area where they may have come from.

The original source of the massive sarsen stones has long been debated, at least four centuries according to the study. The smaller “bluestones” near the center of the circular monument have been traced to an area in Wales, about 200 km away, in an earlier study.

Geologists used geochemical data from the sarsens and compared it to the geochemical signature of different regions.

Texas cave sediment upends meteorite explanation for global cooling

Texas researchers from the University of Houston, Baylor University and Texas A&M University have discovered evidence for why the earth cooled dramatically 13,000 years ago, dropping temperatures by about 3 degrees Centigrade.

The evidence is buried in a Central Texas cave, where horizons of sediment have preserved unique geochemical signatures from ancient volcanic eruptions—signatures previously mistaken for extraterrestrial impacts, researchers say.

The resolution to this case of mistaken identity recently was reported in the journal Science Advances.

Challenging a central tenet of chemistry

Steve Granick, Director of the IBS Center for Soft and Living Matter and Dr. Huan Wang, Senior Research Fellow, report together with 5 interdisciplinary colleagues in the July 31 issue of the journal Science that common chemical reactions accelerate Brownian diffusion by sending long-range ripples into the surrounding solvent.

The findings violate a central dogma of chemistry, that and chemical reaction are unrelated. To observe that molecules are energized by chemical reaction is “new and unknown,” said Granick. “When one substance transforms to another by breaking and forming bonds, this actually makes the molecules move more rapidly. It’s as if the chemical reactions stir themselves naturally.”

“Currently, nature does an excellent job of producing molecular machines but in the natural world scientists have not understood well enough how to design this property,” said Wang. “Beyond curiosity to understand the world, we hope that practically this can become useful in guiding thinking about transducing chemical energy for molecular motion in liquids, for nanorobotics, precision medicine and greener material synthesis.”

Metal-breathing bacteria could transform electronics, biosensors, and more

When the Shewanella oneidensis bacterium “breathes” in certain metal and sulfur compounds anaerobically, the way an aerobic organism would process oxygen, it produces materials that could be used to enhance electronics, electrochemical energy storage, and drug-delivery devices.

The ability of this bacterium to produce molybdenum disulfide—a material that is able to transfer electrons easily, like graphene—is the focus of research published in Biointerphases by a team of engineers from Rensselaer Polytechnic Institute.

“This has some serious potential if we can understand this process and control aspects of how the bacteria are making these and other materials,” said Shayla Sawyer, an associate professor of electrical, computer, and systems engineering at Rensselaer.

Solving materials problems with a quantum computer

Quantum computers have enormous potential for calculations using novel algorithms and involving amounts of data far beyond the capacity of today’s supercomputers. While such computers have been built, they are still in their infancy and have limited applicability for solving complex problems in materials science and chemistry. For example, they only permit the simulation of the properties of a few atoms for materials research.

Scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory and the University of Chicago (UChicago) have developed a method paving the way to using quantum computers to simulate realistic molecules and complex materials, whose description requires hundreds of atoms.

The research team is led by Giulia Galli, director of the Midwest Integrated Center for Computational Materials (MICCoM), a group leader in Argonne’s Materials Science division and a member of the Center for Molecular Engineering at Argonne. Galli is also the Liew Family Professor of Electronic Structure and Simulations in the Pritzker School of Molecular Engineering and a Professor of Chemistry at UChicago. She worked on this project with assistant scientist Marco Govoni and graduate student He Ma, both part of Argonne’s Materials Science division and UChicago.

Hydrogel mimics human brain with memorizing and forgetting ability

Hokkaido University researchers have found a soft and wet material that can memorize, retrieve, and forget information, much like the human brain. They report their findings in the journal Proceedings of the National Academy of Sciences (PNAS).

The learns things, but tends to forget them when the is no longer important. Recreating this dynamic process in manmade materials has been a challenge. Hokkaido University researchers now report a hydrogel that mimics the dynamic memory function of the brain: encoding information that fades with time depending on the memory intensity.

Hydrogels are flexible materials composed of a large percentage of water—in this case about 45%—along with other chemicals that provide a scaffold-like structure to contain the water. Professor Jian Ping Gong, Assistant Professor Kunpeng Cui and their students and colleagues in Hokkaido University’s Institute for Chemical Reaction Design and Discovery (WPI-ICReDD) are seeking to develop hydrogels that can serve biological functions.

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