Tag Archives: University of Michigan

transparent solar cell

Finally, a fully transparent solar energy harvester

University of Michigan researchers have devised what looks like the world’s first fully transparent solar cell. Think of all of those tall glass buildings; wouldn’t it be nice if all that incoming solar energy was harvested somehow? Likewise, why not let your smartphone charge up a bit while it’s taking a tan. Of course this isn’t a new idea, but previous attempts are rather unattractive because the compromise makes windows too shady or dark. After all, the purpose of a window is to let light in, not make energy. Ideally, you’d want them harness energy as well, complementary. The new system devised at UM is exciting because it offers exactly this: energy generation, with no compromise in visibility.

transparent solar cell

Image: University of Michigan

Obviously, windows are transparent because they let most of the incoming light through. This eventually bounces off your retina and allows you to see outside or inside. This is why all those solar cells meant to line windows make them look dark and make rooms inside shady. They have to absorb some of those light frequencies. The researchers at UM took an alternate route.

As you can see in these quite impressive photos, their system is fully transparent. That’s because the glass itself is not a solar cell – it’s a transparent luminescent solar concentrator (TLSC). The TLSC is made of organic salts tuned to only absorb ultra-violet and infrared energy, the kind of light frequencies you can’t see. The salt then luminesce at another infrared frequencies that gets picked up by tiny plastic channels that line the edges of the “glass” and direct the infrared rays to tiny conventional solar cells.

transparent solar cell

Image: University of Michigan

As you might have guessed, these score some terrible efficiencies. According to the paper, the TLSC has a rated efficiency of 1%, but the researchers think 5% should be possible. Non-transparent luminescent concentrators (which bathe the room in colorful light) max out at around 7%. Left alone, this doesn’t seem like much, but multiplied by every window in a building this could add up to power the LED lights in rooms, for instance. Definitely, a new awesome fact about solar energy.

Keep in mind this is an innovation. Don’t expect it to be efficient or affordable, yet. I do find this kind of research inspiring however. A lot of people seem to be against the idea of solar panels because they’re obtrusive and ugly. Sure, there are pros and cons to solar panels. Personally, I enjoy them, but hey that’s just me. By blending energy generation, solar cells might garner a new following.

Science finds the most and least addictive foods

Scientists from the University of Michigan have found which are the most and least addictive foods in the world. They gathered data from over 500 participants and found that the most addictive foods are (no surprise) pizza, ice cream and chocolate, while the least addictive ones are cucumbers, carrots, beans and rice.

Pizza was the most addictive food, according to questionnaires answered by 400 people.


It’s been debated for years whether or not food addiction actually exists; naturally, we are all addicted to food in the sense that we have to eat in order to survive. But can you actually be addicted to certain foods, like hamburgers? There is still no general consensus on this, but biologists seem to dismiss this idea, while many psychologists claim that food addiction is a real, serious problem – there are documented cases with people going through withdrawal-like symptoms when living without certain foods. With this in mind, a researcher from the University of Michigan and one from the New York Obesity Research Center, the Department of Medicine set out to find what are the most addictive foods.

For this, they asked participants to answer questions based on the Yale Food Addiction Scale. The scale was designed in 2009 by Yale University’s Rudd Center for Food Policy and Obesity and asks people to answer 25 questions on how much they like a certain food. The scale asks participants to count the number of times they’ve agreed with sentences like, “I eat to the point where I feel physically ill” or “I spend a lot of time feeling sluggish or fatigued from overeating,” to help them identify the biggest offenders. Scientists emphasized that “foods” doesn’t mean only unprocessed foods like fruits and vegetables, but can also apply to processed foods.

However, when the same study was conducted on undergrads, chocolate turned out to be the most addictive food.

Study 1 – the undergraduates

They conducted two separate studies to see what foods are considered problematic – how much is a certain food overeaten or eaten up to the point where it causes physical discomfort. The first study was conducted on 120 undergraduates. who were recruited from flyers on campus or through the University of Michigan Introductory Psychology Subject Pool. Students received either financial compensation or study credit for their time.

No surprises there, chocolate took the top spot, with over 1 in 4 people considering chocolate problematic. Ice cream, french fries and pizza followed, again, rather expectedly. But there were also some surprises: breakfast cereals were more problematic than soda or fried chicken, while water was considered to be more problematic than cucumbers or beans… I guess no one really loves beans.


“As hypothesized, highly processed foods (with added fat and/or refined carbohydrates) appeared to be most associated with behavioral indicators of addictive-like eating,” the study writes.

Study 2

Ice is always one of the favorites.

The team also conducted a second study, on almost 400 participants.

“A total of 398 participants were recruited using Amazon’s Mechanical Turk (MTurk) worker pool to complete a study about eating behaviors and were compensatedfor their time”.


So this is the chart of what can be considered the most addictive foods. Interestingly enough, results were slightly different. Pizza took the top spot and chocolate had to settle for second. Chips, cookies and ice cream come closely after. Breakfast cereal dropped significantly, and the least popular food is… the cucumber.

I was surprised to find bananas close to the bottom of the list, even under water. But what’s really the takeaway here is that virtually all the addictive foods are processed.

“In summary, the current study found that highly processed foods, with added amounts of fat and/or refined carbohydrates (e.g., sugar, white flour), were most likely to be associated with behavioral indicators of addictive-like eating. Additionally, foods with high GL were especially related to addictive-like eating problems for individuals endorsing elevated symptoms of “food addiction.” Individuals endorsing symptoms of addictive-like eating behavior may be more susceptible to the large blood sugar spike of high GL foods, which is consistent with the importance of dose and rate of absorption in the addictive potential of drugs of abuse,” the study concludes.

Natural gas is not a clean energy bridge, further studies find

A trio of newly published studies showed once again that natural gas is not a clean energy bridge – the studies highlighting the various problems associated with natural gas.

Natural gas will not dawn a cleaner day in terms of energy. Image via Ohio Citizen.

Firstly, it was shown that emissions databases underestimate the methane released from fossil-fuel extraction in the U.S. Southwest.

“A global gas boom is not a replacement for energy and climate policies,” write Steven J. Davis and Christine Shearer of the University of California, Irvine, in commentary accompanying one paper.

The team, which was lead by Eric A. Kort of the University of Michigan, Ann Arbor used satellite observations to map how that actual methane emissions in that region are about 2 to 3.5 times more than estimated. The results show that we need to reconsider natural gas as a clean substitute for coal and as a bridge towards sustainable development.

[Journal Reference: Eric A. Kort et al. Four corners: The largest US methane anomaly viewed from space. DOI: 10.1002/2014GL061503]

In a separate study, researchers led by Haewon C. McJeon of Pacific Northwest National Laboratory looked at the effects of low-cost, abundant natural gas in an integrated global energy. In other words, he analyzed what would happen to the global energy market if abundant and cheap gas would be available – something which is quite possible in the near future.

What he found is that as natural gas becomes cheaper it will replace coal and fuel less emissions, but it might also stunt emerging renewable energy sources, such as wind and solar.

[Journal Reference: Haewon McJeon et al. Limited impact on decadal-scale climate change from increased use of natural gas. Nature (2014) doi:10.1038/nature13837]

In the third study, a team led by Thomas Gibon and Edgar G. Hertwich at the Norwegian University of Science & Technology conducted global, long-term life-cycle assessments of low-carbon systems (photovoltaic and solar thermal, wind, and hydropower for instance) and showed that implementing such systems at a large scale would not only double the double the world’s electricity supply by 2050, but it will also stabilize or even decrease greenhouse gas emissions. They showed that unlike natural gas, renewable energy can lead to a sustainable future.

[Journal Reference: Edgar G. Hertwich et al. Integrated life-cycle assessment of electricity-supply scenarios confirms global environmental benefit of low-carbon technologies. doi: 10.1073/pnas.1312753111]

To sum it up, the scientific evidence is starting to add up and show that natural gas, while cleaner than coal, is not a solution. It may act like a temporary buffer, like a band-aid you put to stop the bleeding, but it won’t cure the injury. We need to find other, better ways of providing energy for the growing population.


Mothers teach babies fear through smell

Babies can learn what to fear from the first days of life simply by smelling their distressed mothers, a new study has shown. This doesn’t only work after the pregnancy, but also during it and even before – if a mother experiences something specific which makes her fearful.

It’s the first direct observation of this kind – University of Michigan and New York University researchers studied mother rats who had learned to fear the smell of peppermint – theyalso showed that the mothers passed this fear on to their offspring and also pinpointed the exact area of the brain where the learning of fear takes places in the first days of life.

This may help explain something which has puzzled biologists for decades – how is it that a mother’s traumatic experiences are passed on to her offspring?

“During the early days of an infant rat’s life, they are immune to learning information about environmental dangers. But if their mother is the source of threat information, we have shown they can learn from her and produce lasting memories,” says Jacek Debiec, M.D., Ph.D., the U-M psychiatrist and neuroscientist who led the research.

So in a way, even before they can actually accumulate knowledge of their own, they get a taste (or rather, a smell) of their mothers’ experience.

“Our research demonstrates that infants can learn from maternal expression of fear, very early in life,” he adds. “Before they can even make their own experiences, they basically acquire their mothers’ experiences. Most importantly, these maternally-transmitted memories are long-lived, whereas other types of infant learning, if not repeated, rapidly perish.”

In order to figure this out, they devised an experiment which involved making mother rats fear the smell of peppermint by exposing them to non harmful, but unpleasant electric shocks while they smelled the scent, before they were pregnant. Then after they gave birth, the team exposed the mothers to just the minty smell, but didn’t deliver the shocks. They found that newborns quickly picked up on the fear – even though they had no direct reason to fear it. They could learn their mothers’ fears even when the mothers weren’t present.

Using special brain imaging, and studies of genetic activity in individual brain cells and cortisol in the blood, they found that this learning takes place in the lateral amygdala. The amygdala is present in virtually all evolved mammals, playing a complex role in the in the processing of memory, decision-making, and emotional reactions.

Researchers now hope to conduct the same kind of study for mothers and their babies, but they have every reason to believe they will get similar results.