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Comment by Dr. Krishna Kumari Challa on November 6, 2024 at 9:17am

Spraying rice with zinc oxide nanoparticles protects yields during heat waves

A small team of horticulturists has found that spraying rice plants with a zinc oxide nanoparticle solution helps them better handle the stress of a heat wave. In their study, published in Proceedings of the National Academy of Sciences, the group conducted experiments involving spraying rice plants in a heated greenhouse.

Prior research has shown that heat waves can reduce rice yields or kill plants altogether, depending on the severity of the heat wave. Because of that, plant scientists have been looking for ways to help plants survive the likely increase in number and severity of heat waves expected due to global warming. The research team found that zinc oxide nanoparticles may be one such tool.

Prior research has also shown that zinc oxide is a natural part of plant metabolism—rice farmers have used it as a form of fertilizer for many years.

More recently, researchers have found that applying zinc nanoparticles is a much more efficient approach—it allows the particles to pass through the pores in leaves.

The team wondered if zinc oxide might also help rice plants maintain their yields during heat waves. To find out, the researchers planted rice in a climate-controlled greenhouse. Once the plants were grown, the team raised the temperature to 37°C for six consecutive days. During the induced heat wave, they sprayed some of the plants with a zinc oxide nanoparticle solution, while the other plants were only watered. Upon harvesting the rice, the research team found that those plants that had been sprayed with zinc oxide nanoparticles had yields that were 22.1% greater than the plants that had been sprayed with water alone.

In taking a closer look at the rice grains, the research team also found that they contained more nutrients, as well. In conducting another similar experiment, the researchers found that spraying rice plants with zinc oxide nanoparticles also led to increased yields compared to those not sprayed even when there was no heat wave.

Shuqing Guo et al, Zinc oxide nanoparticles cooperate with the phyllosphere to promote grain yield and nutritional quality of rice under heatwave stress, Proceedings of the National Academy of Sciences (2024). DOI: 10.1073/pnas.2414822121

Comment by Dr. Krishna Kumari Challa on November 5, 2024 at 9:51am

Why do flowers wilt? 

Wilting flowers might not signal poor flower or plant health, but rather the effects of a sophisticated resource management strategy in plants, millions of years in the making.

A study in the journal Plant Biology by researchers from Macquarie University and international collaborators has shown for the first time that plants reuse resources from wilting flowers to support future reproduction.

It turns out the plants were playing a longer game than we anticipated, not using their reclaimed resources immediately, but saving them for the next flowering season.

Plants have evolved diverse strategies for managing their flowers after they've served their primary reproductive function, with wilting just one of several possible approaches.

Not all plants follow the flower wilt pattern; flowers will still bloom on some plants long after they can be fertilized and after they stop producing nectar.

Flowers make the whole plant more attractive to pollinators even when they are just there as part of the overall display.

Some plants will even drop their blooms well before they wilt. For example, jacaranda flowers that seem perfectly good will just drop to the ground; frangipani trees will also shed intact flowers rather than have them wilt.

The study tested resource reuse in different ways.

Results showed plants with wilting flowers were more likely to reflower the next season than those where wilting was prevented. The study also considered other factors that might influence seed production, such as flowering stem height, number of flowers per stem, and flower position. Taller flowering stems, for example, produced more seeds and heavier seeds, as did stems with more flowers. But flowers positioned lower down on the plant tended to have fewer seeds, and seeds that weighed less.

 G. H. Pyke et al, Why do flowers wilt?, Plant Biology (2024). DOI: 10.1111/plb.13720

Comment by Dr. Krishna Kumari Challa on November 5, 2024 at 9:16am

Deep sea rocks suggest oxygen can be made without photosynthesis, deepening the mystery of life

Oxygen, the molecule that supports intelligent life as we know it, is largely made by plants. Whether underwater or on land, they do this by photosynthesizing carbon dioxide. However, a recent study demonstrates that oxygen may be produced without the need for life at depths where light cannot reach.

The authors of a recent publication in Nature Geoscience were collecting samples from deep ocean sediments to determine the rate of oxygen consumption at the seafloor through things like organisms or sediments that can react with oxygen. But in several of their experiments, they actually found oxygen was increasing as opposed to decreasing as they would have expected. This left them questioning how this oxygen was being produced.

They found that this "dark" oxygen production at the seafloor seems to only happen in the presence of mineral concentrates called polymetallic nodules and deposits of metals called metalliferous sediments. The authors think the nodules have the right mixture of metals and are densely packed enough for an electrical current to pass through for electrolysis, creating enough energy to separate the hydrogen (H) and oxygen (O) from water (H₂O).

The authors also suggested that the amount of oxygen created may fluctuate depending on the number and mixture of nodules on the ocean floor.

https://www.nature.com/articles/s41561-024-01480-8

Comment by Dr. Krishna Kumari Challa on November 5, 2024 at 9:11am

They found that cooling efficiency follows a power law across scales—from as small as 120 by 120 meters to as large as regions covering the entire city. The relationship holds across all four of the studied cities, which are in very different climates. This suggests that it could be used to predict the amount of additional tree cover needed to achieve specific heat mitigation and climate adaptation goals in cities worldwide.
While the paper provides essential information for decision-making at the municipal level, the researchers caution that urban planners may also need to work at smaller scales to ensure that urban trees—and their potential benefits—are distributed equitably across the city, and with community buy-in.

Jia Wang et al, A scaling law for predicting urban trees canopy cooling efficiency, Proceedings of the National Academy of Sciences (2024). DOI: 10.1073/pnas.2401210121

Part 2

Comment by Dr. Krishna Kumari Challa on November 5, 2024 at 9:09am

How many trees does it take to cool a city? Researchers develop tool to set urban tree canopy goals

Cities around the globe are increasingly experiencing dangerous heat as urban concrete and asphalt amplify rising temperatures. Tree-planting programs are a popular, nature-based way to cool cities, but these initiatives have been largely based on guesswork and extrapolation. A study published recently in Proceedings of the National Academy of Sciences offers a new tool for urban planners and decision makers to set more specific and science-based city-wide greening goals.

Trees are good at cooling because they pump a lot of water from the ground into the air, and when that water evaporates at the leaf surface, it absorbs a vast amount of heat. That's just the physics of evaporation. The shade provided by trees also helps with cooling.

To date, most studies measuring the cooling effects of urban trees focus on the hyperlocal level, such as on a particular street or neighborhood. When the urban tree canopy expands by 1%, for example, nearby temperatures may decrease by 0.04 to 0.57 degrees Celsius.

But how much tree canopy do we actually need for the whole city?

Researchers set out to determine how trees' cooling efficiency—the temperature reduction associated with a 1% increase urban tree canopy—changes across larger areas.

The team analyzed satellite imagery and temperature data from four cities with very different climates: Beijing and Shenzhen in China, and Baltimore and Sacramento in the US. Baltimore and Beijing are temperate, Shenzhen is subtropical, and Sacramento is in a Mediterranean climate zone.

First, they divided each city into pixels approximately the size of a city block. For each pixel, they measured the land surface temperature and how much of the ground was covered by trees. Then they ran the same analyses across larger and larger sections of each city, spanning the neighborhood level, city level, and beyond. Finally, they calculated how the mathematical relationship between greenery and temperature—the cooling efficiency—changed at different scales.

Overall, the team discovered that the cooling efficiency of urban trees increased at larger scales. But it did so at a slower rate at larger unit sizes. In Beijing, for example, a 1% increase in canopy at the block level decreases temperature by about 0.06 degrees, whereas a 1% increase in canopy at the city level could decrease temperature by about 0.18 degrees.
The additional benefit at larger scales seems to come from being able to include large groups of trees, which have a larger cooling capacity.

With greater clarity about the relationships between area, tree canopy cover, and cooling effects, the paper makes it possible to predict cooling effects at the whole-city scale, offering a valuable tool for managers to set urban tree canopy goals to reduce extreme heat.

Part 1

Comment by Dr. Krishna Kumari Challa on November 5, 2024 at 9:02am

Rainwater samples reveals it's literally raining 'forever chemicals'

PFAS are in rainwater. And it is the latest evidence the synthetic "forever chemicals"—that have raised health concerns for people and wildlife—hitch a ride on the water cycle, using the complex system to circulate over greater distances.

For more than a year, FIU researchers collected and analyzed 42 rainwater samples across three different sites in Miami-Dade County. A total of 21 perfluoroalkyl and polyfluoroalkyl substances, or PFAS, were detected, including PFOS and PFOA (since phased out of production over cancer concerns), as well as the newer varieties used in manufacturing today.

While profiles of several PFAS matched back to local sources, others did not. According to the study, published in Atmospheric Pollution Research, this suggests Earth's atmosphere acts as a pathway to transport these chemicals far and wide—contributing to the worldwide pollution problem.

PFAS are practically everywhere. Now scientists are able to show the role air masses play in potentially bringing these pollutants to other places where they can impact surface water and groundwater.

Widely used in consumer products—non-stick cookware, clothing, cosmetics, food packaging, detergents and firefighting foams, to name a few—PFAS were purposefully created to be almost indestructible. They don't break down easily or simply go away.

Once in the environment, they accumulate over time. People can ingest or inhale them, and exposure has been linked to liver and kidney damage, fertility issues, cancer and other diseases. The EPA warned even low levels of exposure can be dangerous, setting strict near-zero limits for some PFAS in drinking water.

It's still not very clear, though, how exactly these long-lived chemicals journey through the environment.

Scientists  have been trying to piece this picture together. They've detected PFAS in drinking water and surface water.

And, subsequently, also found PFAS in animals that live in those areas, including oysters and economically important recreational fish and lobsters. Rain was the natural next place they found it!

PFAS can infiltrate the atmosphere by either evaporation or getting absorbed into microscopic particles and dust. Wind and shifting air currents shuttle them along. Eventually, it rains. As each drop falls to earth, it brings along some of the pollutants. The cycle begins and ends and begins again.

This played out in the team's data.

Maria Guerra de Navarro et al, It's raining PFAS in South Florida: Occurrence of per- and polyfluoroalkyl substances (PFAS) in wet atmospheric deposition from Miami-Dade, South Florida, Atmospheric Pollution Research (2024). DOI: 10.1016/j.apr.2024.102302

Comment by Dr. Krishna Kumari Challa on November 5, 2024 at 8:08am

Insulin resistance caused by sympathetic nervous system over-activation, a paradigm-shifting study finds

Researchers  have found that overnutrition leads to insulin resistance and metabolic disorders through increased activity of the sympathetic nervous system (SNS). The study shows that reducing SNS activity can prevent insulin resistance induced by a high-fat diet, suggesting a new understanding of how obesity causes insulin resistance.

Obesity causes type 2 diabetes and metabolic diseases primarily by inducing insulin resistance. Impaired cellular insulin signaling is the most understood mechanism, but it does not always accompany impaired insulin action, indicating other factors must be involved.

The role of the SNS in obesity is complex and somewhat controversial. Previous studies have reported both increased and decreased SNS activity in obese people.

Overnutrition has been known to rapidly increase plasma norepinephrine (NE) levels, indicating overactivation of the SNS. Methods that directly measure SNS activity, such as nerve recordings and NE turnover, often report increased SNS activity in obesity.

In contrast, studies focusing on adrenergic signaling pathways sometimes report reduced catecholamine responses, interpreted as decreased SNS activity.

This discrepancy may be explained by the development of catecholamine resistance due to chronic sympathetic overactivation, leading to diminished physiological responses despite elevated NE levels.

In a study titled "Overnutrition causes insulin resistance and metabolic disorder through increased sympathetic nervous system activity," published in Cell Metabolism, the researchers investigated the conflicting reports on SNS activity in obesity.

 Kenichi Sakamoto et al, Overnutrition causes insulin resistance and metabolic disorder through increased sympathetic nervous system activity, Cell Metabolism (2024). DOI: 10.1016/j.cmet.2024.09.012

Comment by Dr. Krishna Kumari Challa on November 4, 2024 at 9:26am

Most of the research on the hormonal effect on the brain has been focused on brain communication during cognitive tasks, not the actual structures themselves.
Cyclic fluctuations in HPG-axis hormones exert powerful behavioral, structural, and functional effects through actions on the mammalian central nervous system.
The microstructure of white matter – the fatty network of neuronal fibers that transfer information between regions of gray matter – has been found to change with hormonal shifts, including puberty, oral contraception use, gender-affirming hormone therapy, and post-menopausal estrogen therapy.
To address the menstruation gap in our understanding, the team took MRI scans of their subjects during three menstrual phases: menses, ovulation, and mid-luteal. At the time of each of these scans, the researchers also measured the participants' hormone levels.

The results showed that, as hormones fluctuate, gray and white matter volumes change too, as does the volume of cerebrospinal fluid.

In particular, just before ovulation, when the hormones 17β-estradiol and luteinizing hormone rise, the brains of the participants showed white matter changes suggesting faster information transfer.

Follicle-stimulating hormone, which rises before ovulation, and helps stimulate the ovary follicles, was associated with thicker gray matter.
Progesterone, which rises after ovulation, was associated with increased tissue and decreased cerebrospinal fluid volume.

What this means for the person driving the brain is unknown, but the research lays the groundwork for future studies, and perhaps understanding the causes of unusual but severe period-related mental health problems.
Although we do not currently report functional consequences or correlates of structural brain changes, our findings may have implications for hormone-driven alterations in behavior and cognition," the researchers wrote.
Investigation of brain-hormone relationships across networks is necessary to understand human nervous system functioning on a daily basis, during hormone transition periods, and across the human lifespan.

https://onlinelibrary.wiley.com/doi/10.1002/hbm.26785

Part 2

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Comment by Dr. Krishna Kumari Challa on November 4, 2024 at 9:23am

Scientists Found Structural, Brain-Wide Changes During Menstruation

The constant ebb and flow of hormones that guide the menstrual cycle don't just affect reproductive anatomy. They also reshape the brain, and a study has given us insight into how this happens.

 A team of researchers tracked 30 women who menstruate over their cycles, documenting in detail the structural changes that take place in the brain as hormonal profiles fluctuate.

The results, published in a peer-reviewed study in July this year, suggest that structural changes in the brain during menstruation may not be limited to those regions associated with the menstrual cycle.

"These results are the first to report simultaneous brain-wide changes in human white matter microstructure and cortical thickness coinciding with menstrual cycle-driven hormone rhythms," the researchers wrote.

Strong brain-hormone interaction effects may not be limited to classically known hypothalamic-pituitary-gonadal-axis (HPG-axis) receptor-dense regions."
People who menstruate will experience some 450 or so periods during the course of their lifetimes, so it would be nice to know the different effects they can have on the body, really.

However, although it is something that happens to half the world's population for half their lives, research has been somewhat lacking. Who knows why. Total mystery.
Part 1

Comment by Dr. Krishna Kumari Challa on November 3, 2024 at 12:19pm

Exactly What Happens When an Atom Splits in Two?

The word atom comes from Latin for indivisible. But don't let the name fool you.

A simulation by US theoretical physicists has provided the first fully microscopic characterization of the moment an atom snips in two, revealing fresh insights into an energetic event that came to define a new age in science and technology.

theoretical physicists from Los Alamos National Laboratory and the University of Washington (UW) break the fission process down into four steps.

In the first 10^-14 seconds (give or take), the introduction of a slow-moving neutron forces the nucleus to bulge and rearrange itself in what's described as a saddle point, making the atom look a little like a tiny peanut shell.

This is quickly followed by a far more rapid shift, referred to as saddle-to-scission, where the fragments of the fission process are established. This lasts around 5×10^-21 seconds.

Step three is even faster again, transforming in a relative blink of 10^-22 seconds. In what's called the scission, or neck rupture, the nucleus officially breaks apart.

In the final step, which takes a lazy 10^-18 seconds to unfold, the fission fragments pull themselves into shape and accelerate away, releasing neutrons and gamma rays and potentially generating other decay processes after a brief delay.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.132.242501

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