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Organic compound boosts solar cell stretchability without sacrificing power

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Organic compound boosts solar cell stretchability without sacrificing power


A solar cell that is stretchable without sacrificing power
A photograph showing the flexible solar cell being stretched by two tweezers. Credit: Nature Communications (2024). DOI: 10.1038/s41467-024-49352-4

A solar cell developed by RIKEN physicists can be stretched without greatly affecting its ability to convert light into electricity. It is thus promising for powering the next generation of wearable electronics.

Today’s smart watches can monitor an impressive array of health metrics, while more-specialist wearable devices are being developed for specific medical applications. But such devices need to be recharged periodically.

To eliminate this need, researchers are seeking to develop flexible, wearable solar cells. However, it is vital to ensure that the performance of these solar cells doesn’t drop off when they are stretched by body movements during everyday life.

“We’re focusing on making very thin, flexible devices. But such devices don’t have intrinsic stretchability,” explains Kenjiro Fukuda of the RIKEN Center for Emergent Matter Science. “Rather, they’re similar to plastic wrap used to wrap food—you can maybe stretch them by 1% or 2%, but 10% is impossible since they tear easily.”

Fukuda and his team are trying to overcome this problem by developing solar cells that are intrinsically stretchable.

“Our approach is very simple—we use stretchable materials for every functional layer in a device,” says Fukuda. “But while the concept is simple, the method is highly challenging since we have to strike a balance between the stretchability of each layer and its performance.”

Now, Fukuda and his co-workers have realized a high-performance flexible solar cell that exhibits exceptional stretchability. The research is published in the journal Nature Communications.

The cell’s power conversion efficiency drops by only 20% when the solar cell is stretched by 50% (i.e., stretched to 1.5 times its original, unstretched length). Furthermore, it retains 95% of its initial power conversion efficiency after being stretched 100 times by 10%.

The key to realizing such device stretchability lay in the team incorporating an organic compound called ION E in the electrode layer of the solar cell. They added ION E to enhance the stretchability of the electrode, but they discovered that it had another, unexpected benefit—it enhanced the adhesion between the electrode and the layers above and below it.

“This came as a nice surprise for us,” says Fukuda. “We hadn’t anticipated that ION E would increase the adhesion between layers.”

Thanks to these two effects, the electrode can take up some of the strain from the active layer above it (which converts light into electrons), improving the stretchability of the whole device.

The long-term goal is to create a stretchable organic solar cell that has a large area, Fukuda notes. “One obstacle to achieving this is the low conductivity of the polymer used to convey the generated electricity,” he says. “We’re now looking into ways to overcome this bottleneck.”

More information:
Jiachen Wang et al, Intrinsically stretchable organic photovoltaics by redistributing strain to PEDOT:PSS with enhanced stretchability and interfacial adhesion, Nature Communications (2024). DOI: 10.1038/s41467-024-49352-4

Citation:
Organic compound boosts solar cell stretchability without sacrificing power (2024, October 10)
retrieved 10 October 2024
from https://techxplore.com/news/2024-10-compound-boosts-solar-cell-stretchability.html

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Rental crisis in regional cities prompts rethinking of moves

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Rental crisis in regional cities prompts rethinking of moves


house key
Credit: Pixabay/CC0 Public Domain

James Cook University researchers say Cairns is a prime example of a regional city where the rental housing crisis is making people who have moved to the city rethink their choice—and they say city planners must act if regional areas want such people to stay.

Rana Dadpour is a Research Fellow at JCU’s Cairns Institute. She led a study now published in Australian Planner in which she interviewed people who moved to Cairns between 2016 and 2021.

“The group we looked at were ‘amenity migrants.’ Unlike economic migrants, amenity migrants are often driven by non-economic factors, including the desire for a better lifestyle. They are typically well-educated, mobile individuals who have the flexibility to choose where they live,” said Dr. Dadpour.

She said Cairns exemplifies a prime destination for amenity migrants, but many reported struggles with rental housing affordability, suitability and availability.

“We found many amenity migrants in Cairns face problems in the rental market, often leading to compromises in their living conditions and a sense of frustration and uncertainty. This negatively impacts their sense of belonging and overall life satisfaction,” said Dr. Dadpour.

She said the study reveals housing insecurity can prompt amenity migrants to consider moving again, as they seek more stable and affordable housing options elsewhere.

“We need a holistic understanding of the housing needs of amenity migrants and the development of a different approach by town planners,” said Dr. Dadpour.

She said planners should consider implementing a range of policy measures beyond traditional zoning and land-use planning—for example, incentivizing the development of diverse housing types and tenures, such as density bonuses, co-housing and adaptive reuse of existing buildings.

“Streamlining planning approval processes for innovative housing models can encourage their development. Planners should also work in collaboration with other stakeholders, such as community organizations and social service providers.

“By adopting a proactive and inclusive approach, grounded in practical examples and informed by research, planners can contribute to the development of more sustainable and equitable communities in regional cities like Cairns,” said Dr. Dadpour.

More information:
Rana Dadpour et al, Paradise lost? Rental housing insecurity and the lived experiences of amenity migrants in Cairns, Australia, Australian Planner (2024). DOI: 10.1080/07293682.2024.2405673

Citation:
Rental crisis in regional cities prompts rethinking of moves (2024, October 10)
retrieved 10 October 2024
from https://phys.org/news/2024-10-rental-crisis-regional-cities-prompts.html

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Declines in plant resilience threaten carbon storage in the Arctic

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Declines in plant resilience threaten carbon storage in the Arctic


Declines in plant resilience threaten carbon storage in the Arctic
Vegetation resilience pervasively decreased in southern boreal forests while increased in Arctic tundra. Credit: Nature Ecology & Evolution (2024). DOI: 10.1038/s41559-024-02551-0

Rapid warming has impacted the northern ecosystem so significantly that scientists are concerned the region’s vegetation is losing the ability to recover from climate shocks, suggests a new study.

Their findings revealed that due to frequent disturbances like wildfires that raze down vegetation and persistent drought and deforestation that starve both the land and wildlife, the resilience of many plant communities in southern boreal forests—or their ability to recover after these events—significantly decreased over time.

This may affect the Arctic carbon budget, foreshadowing a future where the region is likely to become a carbon source instead of remaining a carbon sink due to its limited capacity to absorb atmospheric carbon dioxide in the coming decades.

This is because Arctic and boreal regions have warmed several times faster than other places around the globe and further warming is expected in the near future, said Yue Zhang, lead author of the study and a graduate student in Earth sciences at The Ohio State University.

“When we talk about the response of forests to climate change, most of the time we’re thinking about the tropical rainforest,” said Zhang. “But remote boreal forests are really important in terms of their vast extent, large carbon storage and potential to mitigate climate change.”

The study was recently published in Nature Ecology & Evolution.

To better understand how the region’s ecosystem changed because of increased warming, researchers used historical data from NASA’s Arctic-Boreal Vulnerability Experiment (ABoVE) program to remotely sense subtle changes in greenness in Alaska and western Canada between 2000 and 2019. They were able to estimate the time-varying speed of vegetation recovery from small fluctuations or large losses, even in areas where large losses have not happened yet.

The study found that while plant resilience in the southern boreal forests notably decreased, even in regions with greening trends, resilience was thought to have increased in most of the Arctic tundra. In addition to fires, other factors like heat and drought could have contributed to declines in plant resilience in the south, and changes in nutrient availability could have helped vegetation thrive in the rest of the Arctic.

While the release of food may benefit plant growth and resilience, the reality is that the rising temperatures that make this possible could also cause Arctic permafrost to melt more quickly than it already is, releasing from the ground as much carbon as 35 million cars emit in a year and hastening the arrival of climate tipping points.

It is uncertain now how much of the carbon will be absorbed by plants and how much will contribute to further warming, said Zhang.

“That’s pretty concerning, because while greening may indicate that productivity and carbon uptake in these regions is increasing now, resilience decline indicates that it may not be sustainable in the longer term,” she said.

According to the study, these shifts are indications that the entire ecosystem is in danger, as a large fraction of southern boreal forests is losing its stability, potentially leading to widespread forest loss and biome shifts.

Greening regions that experience resilience decline at the same time might also signal that the region is struggling to take a few last deep breaths before significant forest loss, said Yanlan Liu, senior author of the study and an assistant professor of Earth Sciences at Ohio State.

This means that while the region could absorb significant amounts of carbon in the short term, scientists expect that if resilience continues to decline, the Arctic boreal ecosystem may not be as effective in mitigating climate in the long term as previously thought.

“Temperature records show this region is warming up to two to four times faster than the global average,” said Liu. “This is a hot spot of vegetation change where studying it can tell us about the ecosystem stability and what it’s capable of tolerating before it transitions into an alternative state through pervasive forest loss.”

The study further revealed that warm and dry areas with high elevation and dense vegetation cover were among the hotspots of resilience decline. Yet because many climate models currently lack consensus on how vegetation change and carbon dynamics contribute to the other, this team’s work will help enhance such models by informing scientists of where vegetation changes are likely to occur.

Ultimately, said Zhang, their method revealed more nuanced changes in the health of the region’s vegetation, beyond previously reported greening and browning trends. This method also provides researchers a tool to identify potential vegetation loss in other regions in the coming decades.

With plans to continue trying to accurately predict ecosystem changes, researchers note their results warrant more field investigations aimed at better characterizing and understanding the resilience of the region.

“Scientists need to learn to quantify climate-induced risks through diverse lenses,” said Liu. “On top of satellite remote sensing, we need more ground observations to help us identify ways to leverage these findings to inform future resources and risk management strategies.”

More information:
Yue Zhang et al, Warming and disturbances affect Arctic-boreal vegetation resilience across northwestern North America, Nature Ecology & Evolution (2024). DOI: 10.1038/s41559-024-02551-0

Citation:
Declines in plant resilience threaten carbon storage in the Arctic (2024, October 10)
retrieved 10 October 2024
from https://phys.org/news/2024-10-declines-resilience-threaten-carbon-storage.html

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part may be reproduced without the written permission. The content is provided for information purposes only.





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Why do some trees lose their leaves while others stay green?

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Why do some trees lose their leaves while others stay green?


fall forest aerial
Credit: Unsplash/CC0 Public Domain

The autumn has arrived and northeastern North America’s forests will soon grace us with a breathtaking palette of reds, yellows and golds. These vivid colors will then fade, giving way to bare branches, as the fallen leaves blanket the forest floor, thereby returning their nutrients to the soil. The spectacle is not as impressive a few degrees farther north, where deciduous trees give way to conifers, which keep their dark green needles through the winter.

These contrasting landscapes are familiar to all of us, but have you ever wondered why some tree species shed their leaves in autumn, whereas others don’t, remaining green throughout the year? Why do these two leaf habits co-exist? Do they reflect an adaptation to their environment? These questions have intrigued ecologists for a long time, but it’s only in the past decades that a clear conceptual and theoretical framework has emerged allowing a better understanding of the ecological significance of this trait.

I am a forest ecologist working at Carbone boréal, a research project of the Université du Québec à Chicoutimi in Canada. Our team studies the role of the boreal forest in the global carbon cycle and the best management practices to mitigate climate change.

Different leaf habits for different habitats

Evergreen tree species are those bearing leaves throughout the year. In Canada, the most common evergreen trees are pines, firs and spruces. In contrast, deciduous tree species like maples, aspens and birches have a bare canopy for a period of the year.

At our latitudes, deciduous trees shed their leaves in the fall to avoid the cold winter, but in other regions of the world, such as in the Mediterranean biome, some deciduous species shed their leaves at the beginning of the summer, a way to avoid water stress. Typically, leaf longevity of deciduous species is only a few months whereas that of evergreen species is longer than a year, which allows the coexistence on the canopy of several cohorts. Black spruce’s needles can, for instance, remain on branches for more than 20 years.

It is thought that the first plants that colonized lands about 400 million years ago were evergreens, and that leaf abscission evolved later under the influence of seasonal and biotic factors, especially in regions characterized by a strong seasonality. Today, evergreen trees are the most abundant in the tropics where there is little seasonality, and in the boreal forest, where, in contrast, the seasons are highly pronounced.

Isn’t it paradoxical?

The explanation for this bimodal distribution of “evergreenness” can be understood through an economical perspective, in which carbon is the main currency.

The carbon economics of plants

All trees, whether deciduous or evergreen, rely on leaves to capture carbon in the form of carbon dioxide (CO2) from the atmosphere through photosynthesis. As carbon is required in large amounts for growth and reproduction, leaves play a major role in plant survival in their respective habitats.

Therefore, trees have evolved leaves of different shapes and structures for capturing carbon as efficiently as possible according to local conditions. For instance, conifers have thick needle-shaped leaves whereas deciduous trees like maples have thin and flat leaves.

The cost of building leaves varies widely depending on the type of leaves. For a given surface, let’s say 1 cm2, thick leaves are heavier and thus more “expensive” to build than thin leaves. Consequently, thick leaves need to live longer to “pay back” the carbon invested for their construction. In contrast, thinner—and therefore “cheaper”—leaves can capture enough carbon during the growing season to pay back the initial investment, and be free to fall.

This carbon economy paradigm is supported by the strong observed correlation worldwide between the leaf mass per area and leaf longevity. One question comes to mind though. While it is totally sensical that thick leaves must live longer to payback their high carbon cost, why don’t thin leaves live longer to maximize CO2 acquisition?

The short answer is that thin leaves are more vulnerable to damage from herbivores, frost, drought, and wind. Thicker, more durable leaves are better protected against these hazards, but they cost more carbon to produce.

Plant strategies behind leaf habits

In the past decades, scientists have found that leaf longevity is the cornerstone of two distinct strategies for plants: slow-return on investment strategy (or conservative strategy) versus fast-return on investment strategy (or acquisitive strategy).

Evergreen and deciduous species are the extreme ends of a leaf economic spectrum. The leaves of evergreen species acquire carbon over the long term and improve nutrient conservation, whereas short-lived leaves favor rapid carbon acquisition.

These two strategies are the results of trade-offs, whereby two or more traits or functions cannot be optimized simultaneously. Maximizing one function comes at the expense of another.

The distribution of leaf habits

The distribution of evergreen and deciduous species across the globe can be explained by the success of these two strategies depending on the environmental conditions.

In environments where resources like sunlight, water, and nutrients are plentiful, deciduous species generally outcompete evergreen species. Building thin leaves offers the advantage of creating a larger surface area for a given amount of biomass, which can collect a larger amount of solar energy, a resource that is necessary for carbon absorption. In these conditions, deciduous trees thrive, growing quickly and shedding their leaves once the growing season ends.

In harsher environments, where nutrients are scarce and the growing season is short, being evergreen provides several advantages.

First, shedding leaves every year is costly both in carbon and in nutrients. Keeping leaves longer reduces annual nutrient losses to the soil and increases the mean residence time of these nutrients in the plant.

Second, their strategy of keeping leaves longer also allows them to capture carbon early in the spring as soon as conditions are favorable. Meanwhile, deciduous trees need time to grow new leaves, which will be able to absorb carbon only after a few weeks, putting them at a disadvantage.

While the carbon economy of plants can alone explain the dominance of evergreens in both the equatorial and the boreal zones, evergreens and deciduous often coexist in various ecosystems because both strategies are efficient enough to ensure the survival of the populations.

In ecology, as always, nothing is straightforward; plant communities are shaped by a multitude of known and hidden variables interacting with one another, making it a challenging task to explain or predict their composition.

Provided by
The Conversation


This article is republished from The Conversation under a Creative Commons license. Read the original article.The Conversation

Citation:
Fall is here: Why do some trees lose their leaves while others stay green? (2024, October 10)
retrieved 10 October 2024
from https://phys.org/news/2024-10-fall-trees-stay-green.html

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Australian report reveals how housing crisis is reshaping young people’s lives

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Australian report reveals how housing crisis is reshaping young people’s lives


'Overwhelmed, hopeless, crushed': Report reveals how housing crisis is reshaping young people's lives
Credit: SHVETS production/Pexels

Australia’s housing crisis is severely impacting young people’s safety, relationships, health and well-being, education, employment, and ability to plan for the future, according to new report launched in Canberra as part of World Homeless Day.

The research developed by Swinburne University of Technology, in partnership with YWCA Australia, details how current housing dynamics are dramatically reshaping the lives and hopes of young women and gender-diverse people across the country.

“Young people described feeling overwhelmed, hopeless, trapped, and crushed by their housing situations. For some, this stems from the daily challenge of simply making ends meet,” says lead author of the report, Swinburne’s Professor Wendy Stone.

A common theme in the report is that many young women or gender-diverse people who are living with family as adults to save on rent are experiencing poor health and well-being.

“The notion of saving money on rent by living at home, but paying with your mental health was common,” says Professor Stone. “For others, the fear that they will never own a home—or if they do, it will require major sacrifice—had a negative impact on their mental health and well-being.”

Swinburne’s team of Professor Wendy Stone, Dr. Sal Clark, Zoë Goodall and Dr. Catherine Hartung interviewed young women and gender-diverse people aged 18- to 30-years-old, nationally.

Young people reported unsafe living conditions, challenging household dynamics, having to move away for affordable housing, and difficulties with dating or romantic relationships.

They found that housing barriers are changing the traditional life course that many young people expected to follow, undermining their sense of what it means to be an “adult.”

Numerous young people feel that buying a home is out of reach or impossible. For women and gender-diverse people, there are more gendered implications. Buying or even renting is seen as unattainable without a partner who can earn more, potentially leading to disadvantage, particularly when considering future children.

“Young people are making huge trade-offs in what they want, just to be able to get by. This isn’t just among those in more vulnerable population groups, it’s widespread around Australia.”

Swinburne’s research team and those impacted have clear ideas about what policy changes are needed and suggest several solutions, including:

  • Further investment in social housing,
  • Stronger rental regulation,
  • Women-specific and LGBTQI-specific housing support, and
  • Widely available information about housing, including education in high school.

“Young people urgently need a seat at the table when it comes to decisions about housing,” says Professor Stone.

“Action is urgently needed from our nation’s leaders. We must ensure young women, young gender-diverse people and young men, have access to affordable and safe housing.”

More information:
Wendy Stone et al, ‘We’ve been robbed’: Young women and gender diverse people’s housing experiences and solutions, (2024). DOI: 10.25916/sut.27108301

Citation:
‘Overwhelmed, hopeless, crushed’: Australian report reveals how housing crisis is reshaping young people’s lives (2024, October 10)
retrieved 10 October 2024
from https://phys.org/news/2024-10-overwhelmed-hopeless-australian-reveals-housing.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.





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