Scholarship & Creativity

Ferns provide model for tiny motors powered by evaporation

Scientists are looking to ferns to create a novel energy-scavenging device that uses the power of evaporation to move itself and provide a method for powering micro and nano devices with just water or heat.

The research started when doctoral student Ruba Borno was exploring another idea. She was interested in mimicking biological devices, specifically microchannels that plants use to transport water, so Michel Maharbiz, assistant professor of electrical engineering and computer science, gave her a book on plants. But something else in the book caught Borno’s attention—the section on how ferns spread their spores.

“It’s essentially a microactuator,” says Maharbiz. The fern sporangium transforms one form of energy—in this case heat via the evaporation of water—into motion. When cells in the outer wall of the sporangium were waterlogged, the sporangium remained closed like a fist, storing the spores safely inside. But when the water in the outer wall evaporated, because of exposure to light, heat or any other evaporation-inducing event, it caused the sporangium to unfurl and eject the spores into the environment.

“Once we saw that, we thought, ‘Oh, we have to build that,’” Maharbiz said.

The method for making the material is simple enough. A wafer is coated with silicone and then hit with light, causing a pattern. The residual pattern is lifted off and that is used for the device. It resembles a curved spine with equally spaced ribs fanning outward from the spine.

To make the device move, Borno says, they load the space between the ribs with water. When the water evaporates, the surface tension of the water pulls on the tips of the ribs so they move toward one another, straightening out the spine of the device. In this way, the closed device opens wide—it moves.

Researchers plan to add electrical components to the device in an attempt to generate electricity. They predict the device will generate the same amount of electricity as other scavenging devices, such as a solar cell in a calculator. The ideal application would be to power a remote sensor where it’s impossible to change the batteries regularly.
—Laura Bailey, News Service

Blacks with bladder cancer have more aggressive tumors,worse survival

Black patients with bladder cancer are 35 percent more likely to die of the disease than white patients, according to a new study from the Comprehensive Cancer Center.

In a study of 93,093 people with bladder cancer, researchers found Black patients were diagnosed with more advanced disease and were more likely to have an aggressive type of tumor, compared to white patients. Black women were more likely than white men or women and Black men to have a more aggressive tumor.

Using data from the National Cancer Institute, researchers looked at patients diagnosed with bladder cancer between 1973 and 1999.

The large time frame allowed the researchers to review trends in five-year intervals. They found that over time more patients were diagnosed with early tumors that had not spread rather than advanced disease.

But in the most recent time interval, 80 percent of white patients were diagnosed with early-stage cancer, while only 68 percent of Black patients were. Black women had the highest proportion of advanced tumors at all time intervals.

Bladder cancer is twice as common in whites as it is in Blacks, but Blacks have lower survival rates. In this study, 24 percent of the Black patients died of bladder cancer compared with 15 percent of the white patients. Even when the researchers compared only the patients with early stage disease, Blacks had lower survival rates than whites.The degree to which the tumor has spread affects treatment options as well as survival. The researchers found fewer Black patients had been treated with minimally invasive surgery and more underwent open surgery to remove their bladder. Black patients were also more likely to receive radiation therapy along with surgery. Also, researchers found Black patients tended to have more aggressive tumors.

Results of the study appear in the September issue of the Journal of Urology. Study authors were Dr. Cheryl Lee, director of the bladder cancer program at the center and associate professor of urology at the Medical School, Rodney Dunn, statistician expert, Candice Williams and Dr. Willie Underwood III, formerly at U-M and now with Wayne State University.
—Nicole Fawcet, U-M Health System

Ancient global warming drove early primates’ dispersal

The continent-hopping habits of early primates have long puzzled scientists, and several scenarios have been proposed to explain how the first true members of the group appeared virtually simultaneously on Asia, Europe and North America some 55 million years ago.

But new research using the latest evidence suggests a completely different migration path from those previously proposed and indicates that sudden, rapid global warming drove the dispersal.

Researchers from U-M, Johns Hopkins University School of Medicine and the Royal Belgian Institute of Natural Sciences focused on Teilhardina, an ancient genus that resembled the saucer-eyed, modern-day primates known as tarsiers. In both Asia and Europe, the genus is the oldest known primate; in North America, it appears in the fossil record around the same time as another primate, Cantius. Previously, scientists had come up with four ways to explain the geographic distribution pattern: primates originated in Africa and spread across Europe and Greenland to reach North America; they began in North America and traveled across a temporary land bridge connecting Siberia and Alaska; they had their origins in Africa or Asia and traveled through North America to reach western Europe; or the group originated in Asia and fanned out eastward to North America and westward to Europe.

In the research, U-M paleontologist Philip Gingerich and coworkers used a carbon isotope curve recently documented on all three continents. Carbon in the atmosphere, earth and living organisms differs in the proportion of carbon-12 and carbon-13 present. A flood of carbon-12 is associated with the onset of an event known as the Paleocene-Eocene thermal maximum (PETM), one of the most rapid and extreme global warming events recorded in geologic history It was during the PETM that modern primates first appeared 55 million years ago. Teilhardina in Asia precedes the maximum flood of carbon-12, Teilhardina in Europe coincides with it, and Teilhardina in North America appears just after the maximum.ased on this evidence, the researchers propose that Teilhardina migrated from south Asia to Europe, crossing the Turgid Straits—an ancient seaway between Europe and Asia—and then spread to North America by way of Greenland within about 25,000 years.
—Nancy Ross-Flanigan, News Service

Bathing safety a concern among older adults
Getting in and out of the bathtub or shower can be a perilous journey for older adults, even when they have bathrooms equipped with safety features, according to research by the U-M Health System.

Researchers videotaped fully clothed people ages 60 and older as they demonstrated how they normally climb in and out of the shower or tub. One-third of the 89 participants in the study had difficulty, such as plopping onto a tub seat or hitting the side of the tub or the shower threshold with their legs.

“We found that there are a lot of independently bathing older adults who have trouble or are unsafe getting into and out of the tub or shower stall,” says lead author Susan Murphy, an occupational therapist and research assistant professor with the Medical School Division of Geriatric Medicine, part of the Department of Internal Medicine. “For older adults, losing the ability to bathe is associated with having falls, fracturing bones, and even being admitted to a nursing home. It is important that we take steps to help to prevent bathing disability before it occurs,” Murphy says.

One of the major problem areas involved sliding glass doors in showers. Three-quarters of participants who used shower stalls with these doors tried to utilize the door for stability or balance.

While the majority of people using both tubs and shower stalls used safe environmental features such as grab bars, 19 percent of participants using a tub were evaluated as using unsafe features, and more than 70 percent of those with shower stalls used unsafe features, such as the glass door, towel bar or a tub seat. One participant had a plastic lawn chair as a tub seat, a particularly dangerous improvisation.

Some safety problems can be fixed easily with the installation of a shower curtain in place of a door, and proper instruction about built-in bathroom safety features (such as grab bars designed to bear weight) for new residents of senior housing facilities. Researchers also suggested better designs for bathrooms in such facilities.

In addition to Murphy, authors were Dr. Neil Alexander, professor in the Division of Geriatric Medicine, Department of Internal Medicine, and director of the Geriatric Research, Education, and Clinical Center, VA Ann Arbor Health Care System; Linda Nyquist, senior research associate-social sciences, Institute of Gerontology; and Debra Strasburg, research physical therapist, VA Ann Arbor Health Care System.
—Katie Gazella, Medical School Communications