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Next-generation sustainable electronics are doped with air

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Next-generation sustainable electronics are doped with air


Semiconductors are the foundation of all modern electronics. Now, researchers at Linköping University, Sweden, have developed a new method where organic semiconductors can become more conductive with the help of air as a dopant. The study, published in the journal Nature, is a significant step towards future cheap and sustainable organic semiconductors.

“We believe this method could significantly influence the way we dope organic semiconductors. All components are affordable, easily accessible, and potentially environmentally friendly, which is a prerequisite for future sustainable electronics,” says Simone Fabiano, associate professor at Linköping University.

Semiconductors based on conductive plastics instead of silicon have many potential applications. Among other things, organic semiconductors can be used in digital displays, solar cells, LEDs, sensors, implants, and for energy storage.

To enhance conductivity and modify semiconductor properties, so-called dopants are typically introduced. These additives facilitate the movement of electrical charges within the semiconductor material and can be tailored to induce positive (p-doping) or negative (n-doping) charges. The most common dopants used today are often either very reactive (unstable), expensive, challenging to manufacture, or all three.

Now, researchers at Linköping University have developed a doping method that can be performed at room temperature, where inefficient dopants such as oxygen are the primary dopant, and light activates the doping process.

“Our approach was inspired by nature, as it shares many analogies with photosynthesis, for example. In our method, light activates a photocatalyst, which then facilitates electron transfer from a typically inefficient dopant to the organic semiconductor material,” says Simone Fabiano.

The new method involves dipping the conductive plastic into a special salt solution — a photocatalyst — and then illuminating it with light for a short time. The duration of illumination determines the degree to which the material is doped. Afterwards, the solution is recovered for future use, leaving behind a p-doped conductive plastic in which the only consumed substance is oxygen in the air.

This is possible because the photocatalyst acts as an “electron shuttle,” taking electrons or donating them to material in the presence of sacrificial weak oxidants or reductants. This is common in chemistry but has not been used in organic electronics before.

“It’s also possible to combine p-doping and n-doping in the same reaction, which is quite unique. This simplifies the production of electronic devices, particularly those where both p-doped and n-doped semiconductors are required, such as thermoelectric generators. All parts can be manufactured at once and doped simultaneously instead of one by one, making the process more scalable,” says Simone Fabiano.

The doped organic semiconductor has better conductivity than traditional semiconductors, and the process can be scaled up. Simone Fabiano and his research group at the Laboratory of Organic Electronics showed earlier in 2024 how conductive plastics could be processed from environmentally friendly solvents like water; this is their next step.

“We are at the beginning of trying to fully understand the mechanism behind it and what other potential application areas exist. But it’s a very promising approach showing that photocatalytic doping is a new cornerstone in organic electronics,” says Simone Fabiano, a Wallenberg Academy Fellow.



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Bird flu: Diverse range of vaccines platforms ‘crucial’ for enhancing human pandemic preparedness

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Bird flu: Diverse range of vaccines platforms ‘crucial’ for enhancing human pandemic preparedness


Vaccination remains the most effective strategy for avian influenza prevention and control in humans, despite varying vaccine efficacy across strains.

That’s according to the authors of a new review which delves into existing research into bird flu vaccines for humans.

Published in the peer-reviewed journal Human Vaccines & Immunotherapeutics, the results of the paper are particularly timely following news last week (Wednesday 22nd May) that the bird flu strain H5N1 had once again, for a second time, jumped from cattle in America to a human — prompting fears of subsequent human-to-human infection, with possible critical consequences.

Instances of the avian influenza were first recognized in US cattle in March. Since then, this strain has mainly spread from cow-to-cow and scientists have discovered very high levels of virus in raw milk (pasteurized milk is safe, having shown viral RNA but not infectious virus). To-date two people, however, are known to have contracted the bird flu virus. Both patients — US farmers — only reported eye symptoms and with treatment they made a full recovery.

Following tests on the first human instance, it was seen that the strain had mutated to be better adapted to mammalian cells, but as long as that human didn’t pass it onto another person it likely stopped the spread at that point. With the second case, the CDC has released a statement to say it has been monitoring influenza surveillance systems intently, especially in impacted states. “There has been no sign of unusual influenza activity in people, including in syndromic surveillance,” they report.

The concern now, though, is that if H5N1 continues to be given the environment in which to mutate (such as in close quarter cattle farms) — and this continues long enough — it has the potential to find a combination that will easily spread to humans.

The results of this new research, carried out by a team at the University of Georgia, USA, suggests vaccines still remain our “primary defense” against potential spread of avian influenzas such as the H5N1 and others assessed.

“The H5N1, H7N9, and H9N2 subtypes of avian influenza virus pose a dual threat, not only causing significant economic losses to the global poultry industry but also presenting a pressing public health concern due to documented spillover events and human cases,” explains lead author Flavio Cargnin Faccin, who alongside his mentor Dr. Daniel Perez of the University of Georgia, USA, analyzed the current landscape of research into human vaccines for these bird flus.

“This deep delve into the landscape of avian influenza vaccines for humans shows vaccination remains the primary defense against the spread of these viruses.”

The team examined studies of vaccines tested in mice, ferrets, non-human primates, and clinical trials of bird flu vaccines in humans, and assessed both established platforms and promising new directions.

The review carried out suggests inactivated vaccines are a safe and affordable option that primarily activate humoral immunity — the part of our immune system that produces antibodies.

Live attenuated influenza vaccines (LAIVs) are known to induce a wider immune response than inactivated vaccines, activating not only antibody production but also mucosal and cellular defenses. In this review, the authors suggest this broader response may offer greater protection, though, the authors suggest further research is needed to fully understand and harness its potential benefits for both human and agricultural applications.

The review also examined alternatives, such as virus-like particle (VLP) vaccines and messenger RNA (mRNA) vaccines, that have emerged more recently. Although VLP vaccines for bird flu have limited clinical trial data in humans, results from studies in mice and ferrets showed promise, the authors found. mRNA vaccines against H5N1 and H7N9 bird flu subtypes also generated a rapid and strong immune response in mice and ferrets, and, while data in humans is scarce, results from a phase 1 study of an H7N9 mRNA vaccine in healthy humans were “encouraging.”

Overall, the team suggests “exploring and employing a diverse range of vaccine platforms,” will be “crucial for enhancing pandemic preparedness and mitigating the threat of avian influenza viruses.”



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When should you neuter or spay your dog?

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When should you neuter or spay your dog?


Researchers at the University of California, Davis, have updated their guidelines on when to neuter 40 popular dog varieties by breed and sex. Their recent paper in Frontiers in Veterinary Science adds five breeds to a line of research that began in 2013 with a study that suggested that early neutering of golden retrievers puts them at increased risk of joint diseases and certain cancers.

That initial study set off a flurry of debate about the best age to neuter other popular breeds. Professors Lynette and Benjamin Hart of the School of Veterinary Medicine, the study’s lead authors, set out to add more breed studies by examining more than a decade of data from thousands of dogs treated at the UC Davis veterinary hospital. Their goal was to provide owners with more information to make the best decision for their animals.

They specifically looked at the correlation between neutering or spaying a dog before 1 year of age and a dog’s risk of developing certain cancers. These include cancers of the lymph nodes, bones, blood vessels or mast cell tumors for some breeds; and joint disorders such as hip or elbow dysplasia, or cranial cruciate ligament tears. Joint disorders and cancers are of particular interest because neutering removes male and female sex hormones that play key roles in important body processes such as closure of bone growth plates.

For the most recent study, they focused on German short/wirehaired pointer, mastiff, Newfoundland, Rhodesian ridgeback and Siberian husky. Data was collected from the UC Davis veterinary hospital’s records that included more than 200 cases for each of these five breeds weighing more than 20 kg (or 44 pounds), spanning January 2000 through December 2020.

The Harts said their updated guidelines emphasize the importance of personalized decisions regarding the neutering of dogs, considering the dog’s breed, sex and context. A table representing guidelines reflecting the research findings for all 40 breeds that have been studied, including the five new breeds, can be found here.

Health risks different among breeds

“It’s always complicated to consider an alternate paradigm,” said Professor Lynette Hart. “This is a shift from a long-standing model of early spay/neuter practices in the U.S. and much of Europe to neuter by 6 months of age, but important to consider as we see the connections between gonadal hormone withdrawal from early spay/neuter and potential health concerns.”

The study found major differences among these breeds for developing joint disorders and cancers when neutered early. Male and female pointer breeds had elevated joint disorders and increased cancers; male mastiff breeds had increased cranial cruciate ligament tears and lymphoma; female Newfoundland breeds had heightened risks for joint disorders; female Ridgeback breeds had heightened risks for mast cell tumors with very early neutering; and Siberian huskies showed no significant effects on joint disorders or cancers.

“We’re invested in making contributions to people’s relationship with their animals,” said Benjamin Hart, distinguished professor emeritus. “This guidance provides information and options for veterinarians to give pet owners, who should have the final decision-making role for the health and well-being of their animal.”

Their combined research studies will soon be available with others in the open access journal, Frontiers of Veterinary Science, as a free e-book, Effective Options Regarding Spay or Neuter of Dogs.

Other researchers on this UC Davis study include: Abigail Thigpen, Maya Lee, Miya Babchuk, Jenna Lee, Megan Ho, Sara Clarkson and Juliann Chou with the School of Veterinary Medicine; and Neil Willits with the Department of Statistics.

The research received a small amount of funding from the Center for Companion Animal Health, but was primarily conducted by the above authors as volunteers.



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Why do Dyeing poison frogs tap dance?

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Why do Dyeing poison frogs tap dance?


The toe tapping behavior of various amphibians has long attracted attention from researchers and pet owners. Despite being widely documented, the underlying functional role is poorly understood. In a new paper, researchers demonstrate that Dyeing poison frogs modulate their taps based on specific stimuli.

Dyeing poison frogs, Dendrobates tinctorius, have been shown to tap their posterior toes in response to a range of prey sizes, from small fruit flies to large crickets. In the present study, the researchers hypothesized that if the tapping has a role in feeding, the frogs would adjust their behavior in response to different environmental cues.

To test their hypothesis, the researchers recorded the frogs under varying conditions. “I used the slow-motion camera on my iPhone to take minute-long videos of the frogs tapping. Afterwards, I went back to each video and counted the number of taps on each foot and how long they were visible since they were often hidden behind a leaf or the frog itself. I used those two numbers to get a “taps per minute” on each foot and added them up,” said Thomas Parrish, a former undergraduate student in the Fischer lab (GNDP), and the first author on the paper.

The researchers first tested whether the frogs tapped their toes more when they were feeding. To do so, the researchers fed the terrariums with half a teaspoon of fruit flies and recorded their hunting.

“We already knew the answer to this, but it was great to see that the tapping increased in the presence of the prey,” said Eva Fischer, an assistant professor of integrative biology. “We wanted to ask ‘Why?’ and we wondered whether it had a function in prey capture or it was just a excitatory response like how dogs wag their tails because they are excited.”

The researchers then used different surfaces to see whether the tapping behavior changed when the frogs could see the prey but not feed on it. They placed the fruit flies in small, clear Petri dishes in the frogs’ home and measured the rate of toe tapping. They found that the frogs had an average of 50 taps/minute when they couldn’t access the flies compared to 166 taps/minute when they fed on free-moving flies.

“The idea was that if they’re excited, we might see something different based on whether they can catch the flies,” Fisher said. “These results suggested that since they kept trying to eat in both cases, the tapping was not just out of excitement.”

The researchers wondered, then, whether the toe taps were a form of vibrational signaling where the frogs used it as a way to startle or distract the prey before they fed. They used four different surfaces to test this question: soil, leaf surfaces, gel, and glass.

“Soil and leaves are natural substances, but soil is not very responsive while leaves are. On the other hand, gels are responsive and glass is not, but they are both unnatural surfaces to frogs,” Fischer said.

They found that while the tap rate differed depending on the surface, with leaves being the highest at 255 taps/minute and glass the lowest at 64 taps/minute, there was no difference in the total number of feeding attempts or success.

“Although we saw that the frogs ate in every context, it was exciting to see that they changed their behavior based on what they’re standing on,” Fischer said. “We were surprised, however, that we didn’t see a difference in how successful they were at eating. It’s possible that the experiment is like sending them to a buffet instead of what happens in the forest where the tapping may help in stirring the prey.”

The researchers are now hoping to understand what other stimuli might trigger this behavior. “Although we’ve conclusively shown that it is important in feeding, it could also be important in other contexts. For example, we have seen that the frogs tap more when there are other frogs nearby, so there may be a social aspect to it,” Fischer said.

They are also interested in studying the underlying biomechanical aspects of the muscles. “It would be cool to look at the anatomy and see how the muscles work,” Fischer said. “Ultimately, we could ask whether all frogs can tap their toes if they have the right muscles or whether there’s something special about the anatomy of poison frogs.”



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