Newly discovered mechanism propels micromotors

Tiny clusters of particles zip forward, spin, or circle depending on their shape

2013-10-15

(Press-News.org) WASHINGTON, D.C. Oct. 15, 2013 -- Scientists studying the behavior of platinum particles immersed in hydrogen peroxide may have discovered a new way to propel microscopic machines. The new mechanism is described in The Journal of Chemical Physics, which is produced by AIP Publishing.

Micro-sized machines operate under very different conditions than their macro-sized counterparts. The high surface-area-to-mass ratio of tiny motors means they require a constant driving force to keep them going. In the past, researchers have relied on asymmetric chemical reactions on the surface of the motors to supply the force. For example, Janus motors, are spherical particles coated with a different material on each side. One of the sides is typically made of a catalyst like platinum, which speeds up the reaction that converts hydrogen peroxide into water and oxygen. When the Janus motor is immersed in hydrogen peroxide, oxygen bubbles form more quickly on the platinum side, pushing the sphere forward.

Researchers from Doshisha University in Kyoto, Japan have now discovered, however, that two-sided materials aren't necessary to make micromotors move. The researchers placed tiny spheres made only of platinum in hydrogen peroxide and observed the particles' movement through a microscope. Although the individual spheres bounced about randomly, the researchers noticed that clumps of particles began to exhibit regular motions. The clumps shaped like teardrops moved forward, those that resembled windmills started to spin, and the boomerang shaped clumps traveled in a circle. After creating a theoretical model of the forces at work, the researchers realized they could explain the regular motions by the asymmetrical drag generated by the different shapes.

The researchers envision combining their new type of motors with existing motors to create easily controllable machines with a versatile range of motions.

Micro- and nano-sized machines may one day ferry drugs around the body or help control chemical reactions, but the Japanese team also sees a more fundamental reason to study such tiny systems.

"Micromotors may be used not only as a power source for micromachines and microfactories, but may also give us significant insight regarding mysterious living phenomenon," said Daigo Yamamoto, a researcher in the Molecular Chemical Engineering Laboratory at Doshisha University and an author on the paper that describes the new motors.

INFORMATION:

The article, " Catalytic micromotor generating self-propelled regular motion through random fluctuation" by Daigo Yamamoto, Atsushi Mukai, Naoaki Okita, Kenichi Yoshikawa and Akihisa Shioi appears in The Journal of Chemical Physics. See: http://dx.doi.org/10.1063/1.4813791

ABOUT THE JOURNAL

The Journal of Chemical Physics publishes concise and definitive reports of significant research in the methods and applications of chemical physics. See: http://jcp.aip.org

ELSE PRESS RELEASES FROM THIS DATE:

Illinois river otters exposed to chemicals banned decades ago

2013-10-15

CHAMPAIGN, Ill. -- Researchers report that river otters in Central Illinois are being exposed to polychlorinated biphenyls (PCBs) and pesticides that were banned in the U.S. in the 1970s and '80s. Their analysis appears in the journal Ecotoxicology and Environmental Safety. The Illinois Department of Natural Resources collected 23 river otters between 2009 and 2011, after the animals were incidentally killed (hit by cars or accidentally caught in traps, for example). The agency passed the carcasses along to researchers at the Illinois Natural History Survey (INHS) for ...

Individuals genetically predisposed to anxiousness may be less likely to volunteer and help others

2013-10-15

COLUMBIA, Mo. -- Scientists increasingly are uncovering answers for human behavior through genetic research. Now, a University of Missouri researcher has found that prosocial behavior, such as volunteering and helping others, is related to the same gene that predisposes individuals to anxiety disorders. Helping such individuals cope with their anxiety may increase their prosocial behavior, the researcher said. "Prosocial behavior is linked closely to strong social skills and is considered a marker of individuals' health and well-being," said Gustavo Carlo, Millsap Professor ...

What makes telenovelas so popular?

2013-10-15

A particular type of consumer enjoys stories with plots, characters, and imagery that allow them to get lost in the narrative, according to a new study in the Journal of Consumer Research. "Stories have the power to change people's behavior," write authors Tom van Laer (ESCP Europe Business School), Ko de Ruyter (Maastricht University), Luca M. Visconti (ESCP Europe Business School), and Martin Wetzels (Maastricht University). "Contemporary examples include the persuasive power of Latin American telenovelas, which influence family planning choices and enrollment in adult ...

Scientists unravel mechanisms in chronic itching

2013-10-15

Anyone who has suffered through sleepless nights due to uncontrollable itching knows that not all itching is the same. New research at Washington University School of Medicine in St. Louis explains why. Working in mice, the scientists have shown that chronic itching, which can occur in many medical conditions, from eczema and psoriasis to kidney failure and liver disease, is different from the fleeting urge to scratch a mosquito bite. That's because chronic itching appears to incorporate more than just the nerve cells, or neurons, that normally transmit itch signals. ...

Pain of poverty sticks, despite support of neighbors or spouses

2013-10-15

Being married or having the support of neighbors to rely on does little to alleviate the symptoms of depression associated with economic hardship often experienced by poor mothers. With these findings, published in Springer's American Journal of Community Psychology, Sharon Kingston of Dickinson College in the US challenges the growing perception that marriage and other forms of interpersonal support can buffer the negative effects of poverty. In studying 1,957 mothers from 80 neighborhoods in Chicago, Kingston examined the combined effect of economic adversity and having ...

This week in Molecular Biology and Evolution

2013-10-15

On the road to our modern human lineage, scientists speculate there were many twist and turns, evolutionary dead ends, and population bottlenecks along the way. But how large were population sizes of common ancestors of the great apes and humans, and does the genetic analysis support the prevailing views of a great bottleneck in primate evolution? Using inferred evolutionary rates of more than 1400 genes and ancestral generation times, Professor Carlos Schrago and colleagues trace population histories backwards across evolutionary time to estimate population sizes for ...

New evidence on lightning strikes: Mountains a lot less stable than we think

2013-10-15

Lightning strikes causing rocks to explode have for the first time been shown to play a huge role in shaping mountain landscapes in southern Africa, debunking previous assumptions that angular rock formations were necessarily caused by cold temperatures, and proving that mountains are a lot less stable than we think. In a world where mountains are crucial to food security and water supply, this has vast implications, especially in the context of climate change. Professors Jasper Knight and Stefan Grab from the School of Geography, Archaeology and Environmental Studies ...

Recovery from childhood ADHD may depend on the pattern of brain development

2013-10-15

Philadelphia, PA, October 15, 2013 – Some people grow out of their childhood attention-deficit/hyperactivity disorder (ADHD) and some don't. In fact, around 50% of individuals diagnosed as children continue to suffer from ADHD as adults. Researchers are trying to understand the reasons why, and relatedly, whether there are any differences that distinguish the two groups. Gender, ethnicity, socioeconomic class, and symptom severity have already been ruled out as potentials. So, perhaps there is a distinguishing variable in the brain? Dr. Philip Shaw at the National Human ...

Halloween candy spooks aging digestive systems! Research in fruit flies helps explain why

2013-10-15

Have you ever wondered why young children can eat bags of Halloween candy and feel fine the next day – compared to adults who experience all sorts of agony following the same junk food binge? Evolution and a gene called Foxo may be to blame. Working in fruit flies, scientists at the Buck Institute have identified a mechanism that helps the flies adapt to changes in diet when they're young; they've discovered that same mechanism gets misregulated as the flies age, disrupting metabolic homeostasis, or balance. In a study appearing in Cell Reports, researchers focus on ...

UT Southwestern reports promising new approach to drug-resistant infections

2013-10-15

DALLAS – Oct. 15, 2013 – A new type of antibiotic called a PPMO, which works by blocking genes essential for bacterial reproduction, successfully killed a multidrug-resistant germ common to health care settings, UT Southwestern Medical Center researchers report. The technology and new approach offer potential promise against the growing problem of antibiotic resistance, the researchers said. The pathogen (germ) – called Acinetobacter – can cause infections from pneumonia to serious blood or wound infections, posing greater risk to people with weakened immune systems, ...

Modular assembly of chiral nitrogen-bridged rings achieved by palladium-catalyzed diastereoselective and enantioselective cascade cyclization reactions

Sally C. Morton, executive vice president of ASU Knowledge Enterprise, presents a bold and practical framework for moving research from discovery to real-world impact

Biochemical parameters in patients with diabetic nephropathy versus individuals with diabetes alone, non-diabetic nephropathy, and healthy controls

[Press-News.org] Newly discovered mechanism propels micromotors
Tiny clusters of particles zip forward, spin, or circle depending on their shape

Newly discovered mechanism propels micromotors

ELSE PRESS RELEASES FROM THIS DATE:

LAST 30 PRESS RELEASES: