Researchers identify and clear efficiency hurdle for organic solar cells

 

The researchers, led by the University of Cambridge, identified a loss pathway in organic solar cells which makes them less efficient than silicon-based cells at converting sunlight into electricity. In addition, they identified a way to suppress this pathway by manipulating molecules inside the solar cell to prevent the loss of electrical current through an undesirable state, known as a triplet exciton.

Their results, reported in the journal Nature, suggest that it could be possible for organic solar cells to compete more closely with silicon-based cells for efficiency.

Organic solar cells, which are flexible, semi-transparent, and cheap, can greatly expand the range of applications for solar technology. They could be wrapped around the exteriors of buildings and can be used for the efficient recycling of the energy used for indoor lighting, neither of which are possible with conventional silicon panels. They are also far more environmentally friendly to produce.

“Organic solar cells can do lots of things that inorganic solar cells can’t, but their commercial development has plateaued in recent years, in part due to their inferior efficiency,” said Dr Alexander Gillett from Cambridge’s Cavendish Laboratory, the paper’s first author. “A typical silicon-based solar cell can reach efficiencies as high as 20 to 25%, while organic solar cells can reach efficiencies of around 19% under laboratory conditions, and real-world efficiencies of about 10 to 12%.”

What's Up Oct. 2021

What's Up for October? What to look for this month at sunrise and sunset, and two brilliant stars vying for the "pole" position.

On October 10th look for the five-day-old crescent Moon to join Venus and bright, orange-colored Antares in the southwest after sunset. Then watch as Venus closes on Antares, for a close conjunction on the 15th and 16th, where the two will be only about a degree and a half apart.

Venus comes within about 1.5° of the bright orange-colored star Antares on Oct. 15 and 16, in the hour or so after sunset. Credit: NASA/JPL-Caltech
During the last week of October, Mercury pops briefly into view for early risers.

Look for it about 10 degrees above the eastern horizon, or about the width of your fist held at arm's length, about 30-45 minutes before sunrise.

In the last week of October, Mercury can be glimpsed briefly in the morning sky before sunrise for those with a fairly clear view of the eastern horizon.

Then on October 30th, in the last couple of hours before daybreak, look for the 24-day-old crescent Moon to join brilliant blue-white star Regulus.

Find the crescent Moon near brilliant star Regulus in the east before dawn on Oct. 30.

All month long, look high overhead early in the evening to find two bright stars that take turns with Polaris being the North Star. Their names are Vega and Deneb. Both of these stars are part of the Summer Triangle, and we introduced the other member of the trio, Altair, in last month's video. To find Vega and Deneb, look high overhead in the first few hours after it gets dark. They'll be two of the brightest stars you can see up there.

In October, look high overhead to find bright stars Vega and Deneb in the few hours after sunset. The pair rotate toward the west, setting in the pre-dawn hours.

Vega is a bluish-white star, and like Altair, it's a fast rotator, spinning every 12 and a half hours, compared to the Sun's 27-day rotation. NASA's Spitzer Space Telescope found Vega to have a debris disk around it that could be similar to regions in our own solar system.

Deneb is a blue-white supergiant star that is fusing hydrogen at a phenomenal rate.

With this sort of fury, the party won't last all that much longer. Deneb is likely headed for an explosive end as a supernova within a few million years. Deneb is much farther away than most bright stars in our night sky. This means it's SUPER luminous to be that bright from so far away. Because it's so bright, it's one of the most distant stars you can see with the unaided eye.

These stars rotate around the northern celestial pole, and this time of year, they dip toward the western horizon before setting in the pre-dawn hours. Both Vega and Deneb are part of a special group of stars that take turns being the pole star in the north, as Earth's axis wobbles in a circle over a period of 26,000 years. For now the distinction of "North Star" belongs to Polaris, for at least a few hundred years more.

Over 26,000 years, Polaris trades the title of North Star with a group of others, including Vega and Deneb. Of these special stars, Polaris is the bright star that coincides closest with the Celestial North Pole.

Finally, October 16th is International Observe the Moon Night, when everyone is invited to learn about the science and exploration of the Moon. Visit this link to find out how you can take part.

Source/Credit: NASA / JPL

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Coral microbiome is key to surviving climate change

Siderastrea radians, Puerto Morelos, Mexico
Image Credit: Monica Medina, Penn State

The microbiomes of corals — which comprise bacteria, fungi and viruses — play an important role in the ability of corals to tolerate rising ocean temperatures, according to new research led by Penn State. The team also identified several genes within certain corals and the symbiotic photosynthetic algae that live inside their tissues that may play a role in their response to heat stress. The findings could inform current coral reef conservation efforts, for example, by highlighting the potential benefits of amending coral reefs with microbes found to bolster corals’ heat-stress responses.

“Prolonged exposure to heat can cause ‘bleaching’ in which photosymbionts (symbiotic algae) are jettisoned from the coral animal, causing the animal to die,” said Monica Medina, professor of biology, Penn State. “We found that when some corals become heat stressed, their microbiomes can protect them from bleaching. In addition, we can now pinpoint specific genes in coral animals and their photosymbionts that may be involved in this thermal stress response.”

Viridiana Avila-Magaña, former student at Penn State and currently a postdoctoral fellow at Colorado University Boulder, noted, “Previous studies on the molecular mechanisms underlying corals’ heat-stress tolerance have tended to focus on just the animal or the photosymbiont, but we now know that the entire holobiont — the coral animal, photosymbiont and microbiome — is involved in the stress response.”

AI can predict cancer risk through mammograms

 

Two normal mammograms showing the difference between a dense breast (left)
 and a fatty breast (right).
Photo credit: National Cancer Institute

As a hereditary disease, breast cancer has affected hundreds of families throughout the state. Annually, an average of 1,190 women are diagnosed with breast cancer in Hawaiʻi. As October approaches in recognition of National Breast Cancer Awareness Month, new public impact research from the University of Hawaiʻi Cancer Center is using artificial intelligence (AI) to improve risk assessment for breast cancer to aid in prevention and early detection, improving breast cancer outcomes for women all over the world.

To reduce unnecessary imaging for breast cancer and costs associated with it, UH Cancer Center Researcher John Shepherd and his colleagues found that AI is able to distinguish between the mammograms of women who are more likely to develop breast cancer later on, and those who are not. The study was published in Radiology.

“Conventional methods of breast cancer risk assessment using clinical risk factors haven’t been that effective,” said Shepherd, study lead author and a professor in the Population Sciences in the Pacific Program (epidemiology). “We thought that there was more in the image than just breast density that would be useful for assessing risk.”

Deep learning model

Compared to commonly used clinical risk factors, a sophisticated type of AI called deep learning has been found to be better at using mammograms to differentiate between women who will and will not be diagnosed with breast cancer in the future. Typically, mammograms provide a measure of breast cancer risk through measurements of breast density. While denser breasts on mammography are associated with a higher risk of cancer, there are other factors hidden in mammograms that are likely to contribute risk.

The study used a data set of more than 25,000 digital screening mammograms from 6,369 women who participated in screening mammography from 2006 to 2014. The researchers trained the deep learning model to find details and signals in the mammogram that might be linked to increased cancer risk. When they tested the deep learning-based model, it underperformed in assessing the risk factors for interval cancer risk (cancers diagnosed between routine screenings), but outperformed clinical risk factors in determining screening-detected cancer risk.

“The results showed that the extra signal we’re getting with AI provides a better risk estimate for screening-detected cancer than other forms of assessment,” said Shepherd. “It helped us accomplish our goal of classifying women into low risk or high risk of screening-detected breast cancer.”

He added, “By ranking mammograms in terms of the probability of seeing cancer in the image, AI is going to be a powerful second reading tool to help categorize mammograms.”

Researchers are planning to replicate the study in Native Hawaiian and Pacific Islander women, two groups that have been underrepresented in breast cancer research. They also want to extend the work beyond cancer risk to look at the risk of different grades of breast cancer, from least to most aggressive.

Learn more about breast cancer causes, prevention, treatment and screening here.

Source/Credit: University of Hawaiʻi/John Shepherd

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Clinical trial produces effective oral antiviral to combat COVID-19

 

Scientists at the University of North Carolina at Chapel Hill say a twice-daily pill – molnupiravir — could change the way COVID-19 is treated. Today’s announcement by Merck Co. to seek emergency authorization by the Food and Drug Administration reflects research and testing conducted at UNC-Chapel Hill.

Strong clinical trial results showed the experimental COVID-19 pill reduced hospitalizations and deaths by half in people recently infected with coronavirus. Carolina began working on molnupiravir in 2016 and showed the drug could be a weapon against coronaviruses and future pandemics.

“This is a real game changer for a pandemic like COVID-19 because it allows us to treat people quicker with a method that’s convenient and accessible,” said William A. Fischer II, an associate professor of pulmonology and critical care at the UNC School of Medicine and director of emerging pathogens at the UNC Institute for Global Health and Infectious Diseases.

US Army backs ‘sleeping cap’ to help brains take out the trash

 

Rice University engineers, in collaboration with Houston Methodist and Baylor College of Medicine, are developing a noninvasive skullcap to better understand how the brain disposes of metabolic waste while the wearer sleeps. Signals will be acquired will be through electroencephalogram (EEG), rheoencephalography (REG), orbital sonography (OSG) and transcranial doppler (TCD), with modulation through transcranial/transcutaneous brain and nerve electrical simulations (TES) and low-intensity focused ultrasound pulses (LIFUP).
Illustration courtesy of the NeuroEngineering Initiative

How well does your sleeping brain prepare you for a new day? Researchers at Rice University backed by the U.S. Army Military Operational Medicine Research Program (MOMRP) are poised to find out.

Engineers at Rice University’s NeuroEngineering Initiative in partnership with the Institute of Biosciences and Bioengineering (IBB) and physicians at Houston Methodist Hospital and Baylor College of Medicine will develop a “sleeping cap” to analyze the cleansing flow of fluid that drains the brain of common metabolic waste during sleep.

Rice University engineers, in collaboration with Houston Methodist and Baylor College of Medicine, are developing a noninvasive skullcap to better understand how the brain disposes of metabolic waste while the wearer sleeps. Signals will be acquired will be through electroencephalogram (EEG), rheoencephalography (REG), orbital sonography (OSG) and transcranial doppler (TCD), with modulation through transcranial/transcutaneous brain and nerve electrical simulations (TES) and low-intensity focused ultrasound pulses (LIFUP). Illustration courtesy of the NeuroEngineering Initiative

Mars’ Surface Shaped by Fast and Furious

 

Craters and river valleys on the surface of Mars.
A breached crater lake and outlet valley are outlined in white.
Credit: NASA/GSFC/ JPL ASU

On Earth, river erosion is usually a slow-going process. But on Mars, massive floods from overflowing crater lakes had an outsized role in shaping the Martian surface, carving deep chasms and moving vast amounts of sediment, according to a new study led by researchers at The University of Texas at Austin.  

The study, published in Nature, found that the floods, which probably lasted mere weeks, eroded more than enough sediment to completely fill Lake Superior and Lake Ontario.  

“If we think about how sediment was being moved across the landscape on ancient Mars, lake breach floods were a really important process globally,” said lead author Tim Goudge, an assistant professor at the UT Jackson School of Geosciences. “And this is a bit of a surprising result because they’ve been thought of as one-off anomalies for so long.”  

Crater lakes were common on Mars billions of years ago when the Red Planet had liquid water on its surface. Some craters could hold a small sea’s worth of water. But when the water became too much to hold, it would breach the edge of the crater, causing catastrophic flooding that carved river valleys in its wake. A 2019 study led by Goudge determined that these events happened rapidly.  

Remote sensing images taken by satellites orbiting Mars have allowed scientists to study the remains of breached Martian crater lakes. However, the crater lakes and their river valleys have mostly been studied on an individual basis, Goudge said. This is the first study to investigate how the 262 breached lakes across the Red Planet shaped the Martian surface as a whole. 

Geologists solve half-century mystery with a rock from almost two billion years ago

 

Quartzite with traces of burrowing animals. The scale is marked in centimeters.
Credit: Stefan Bengtson/Swedish Museum of Natural History

Geologists have been baffled by perforations in an Australian quartzite (rock), identical in shape to burrows made in sands by crustaceans; the original sandy sediment is a billion years older than the oldest known animals. An international team of scientists has now resolved the mystery.

When animals move, they leave traces, such as dinosaur footprints or the burrows of worms. These reveal how ancient animals moved, how they foraged and how they interacted with one another. Trace fossils are as old as the animal world.

Geologists were therefore stunned by the discovery in Western Australia of traces of burrowing animals in ancient quartzite, a rock type that was formed when sandy sediments were subjected to high pressures and temperatures.

“Quartzite is as hard as concrete and impossible for burrowing animals to penetrate,” said Bruce Runnegar, UCLA professor emeritus in the Department of Earth, Planetary, and Space Sciences and co-author of the new research, published today in the journal Proceedings of the National Academy of Sciences. “The traces would therefore have had to be made while the sand was still loose. But the sand was deposited 1.7 billion years ago — a billion years prior to the appearance of the first animals in the fossil record, and its transformation to quartzite occurred more than 1.2 billion years ago, much earlier than the oldest animal fossils, which are less than 0.6 billion years old.”

A Swedish-Australian-Chinese-American team has now offered a solution to this riddle. The scientists present an explanation that does not require unreasonably ancient animals or concrete-chewing worms with diamond teeth.

The team measured the age of sand in the burrows using unusual radioactive minerals.

“The age turned out to be more than a billion years younger than the enclosing quartzite,” said co-author Birger Rasmussen, adjunct professor at the University of Western Australia. “The burrows could therefore have been made by animals.”

But how can animals burrow through hard quartzite? The answer was given by microscopic investigations, which showed that the grains had first separated at contact surfaces, resulting in a friable matrix, and then been fused again through later deposition of quartz, returning the rock to the state of hard quartzite.

“A similar process produced the stuff of the standing stones of Stonehenge,” Runnegar said.

A window in time had thus been opened to enable burrowing, the researchers report. Through comparisons with surrounding sedimentary strata, the scientists could date this window to about 40 million years ago, during the Eocene epoch of Earth’s history.

“Most likely, the traces were made by crustaceans, which invaded southwestern Australia during a short-lived marine transgression associated with the opening of the Southern Ocean,” said senior author Stefan Bengtson, professor emeritus and paleontologist at the Swedish Museum of Natural History.

“These trace fossils in the ‘wrong’ rocks have been a mystery for half-a-century,” Bengtson said. “We are glad to have been able to demonstrate geological processes that resolve this conundrum.”

Source/Credit: UCLA / Stuart Wolpert

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Staying on long-term antidepressants reduces risk of relapse

 

When people stop taking antidepressants after a long period of use, just over half (56 per cent) experience a relapse within a year, compared to 39 per cent of those who stay on medication, finds a new study led by UCL and involving researchers from the universities of Bristol, Southampton, York and McMaster University in Canada.

The researchers say their findings, published in The New England Journal of Medicine, can help doctors and patients to make an informed decision together on whether or not to stop their antidepressants after recovery from a depressive episode.

The study is the first publication from a large discontinuation trial of people taking antidepressants for multiple years in primary care.

Lead author Dr Gemma Lewis (UCL Psychiatry) said: “Prescriptions of antidepressants have increased dramatically over recent decades as people are now staying on antidepressants for much longer. Until now we didn’t know whether antidepressant treatment was still effective when someone has been taking them for many years.

“We have found that remaining on antidepressants long-term does effectively reduce the risk of relapse. However, many people can stop their medication without relapsing, though at present we cannot identify who those people are.”

Over a third of COVID-19 patients diagnosed with at least one long-COVID symptom

37% of people had at least one long-COVID symptom diagnosed in the 3-6 month period after COVID-19 infection. The most common symptoms were breathing problems, abdominal symptoms, fatigue, pain and anxiety/depression.

This new study from the University of Oxford and the National Institute for Health Research (NIHR) Oxford Health Biomedical Research Centre (BRC) investigated long-COVID in over 270,000 people recovering from COVID-19 infection, using data from the US-based TriNetX electronic health record network.

The study reports on how commonly nine core long-COVID symptoms were diagnosed, and how this rate compared to people recovering from influenza. The nine core long-COVID symptoms, occurring 90-180 days after COVID-19 was diagnosed, comprise: