Comment

Comment by Dr. Krishna Kumari Challa on April 25, 2024 at 11:35am

Octocorals are one of the oldest groups of animals on the planet known to bioluminescence. "So, the question 's when did they develop this ability?"
Researchers had completed an extremely detailed, well-supported evolutionary tree of the octocorals in 2022. They created this map of evolutionary relationships, or phylogeny, using genetic data from 185 species of octocorals.

With this evolutionary tree grounded in genetic evidence, DeLeo and Quattrini then situated two octocoral fossils of known ages within the tree according to their physical features. The scientists were able to use the fossils' ages and their respective positions in the octocoral evolutionary tree to date to figure out roughly when octocoral lineages split apart to become two or more branches.

Next, the team mapped out the branches of the phylogeny that featured living bioluminescent species.

With the evolutionary tree dated and the branches that contained luminous species labeled, the team then used a series of statistical techniques to perform an analysis called ancestral state reconstruction.
If we know these species of octocorals living today are bioluminescent, we can use statistics to infer whether their ancestors were highly probable to be bioluminescent or not. The more living species with the shared trait, the higher the probability that as you move back in time that those ancestors likely had that trait as well.
The researchers used numerous different statistical methods for their ancestral state reconstruction, but all arrived at the same result: Some 540 million years ago, the common ancestor of all octocorals were very likely bioluminescent. That is 273 million years earlier than the glowing ostracod crustaceans that previously held the title of earliest evolution of bioluminescence in animals.
The octocorals' thousands of living representatives and relatively high incidence of bioluminescence suggests the trait has played a role in the group's evolutionary success. While this further begs the question of what exactly octocorals are using bioluminescence for, the researchers said the fact that it has been retained for so long highlights how important this form of communication has become for their fitness and survival.

Evolution of bioluminescence in Anthozoa with emphasis on Octocorallia, Proceedings of the Royal Society B: Biological Sciences (2024). DOI: 10.1098/rspb.2023.2626. royalsocietypublishing.org/doi … .1098/rspb.2023.2626

Part 2

Comment by Dr. Krishna Kumari Challa on April 25, 2024 at 11:31am

Bioluminescence first evolved in animals at least 540 million years ago, pushing back previous oldest dated example

Bioluminescence first evolved in animals at least 540 million years ago in a group of marine invertebrates called octocorals, according to the results of a new study from scientists with the Smithsonian's National Museum of Natural History.

The results, published April 23, in the Proceedings of the Royal Society B: Biological Sciences, push back the previous record for the luminous trait's oldest dated emergence in animals by nearly 300 million years, and could one day help scientists decode why the ability to produce light evolved in the first place.

Bioluminescence—the ability of living things to produce light via chemical reactions—has independently evolved at least 94 times in nature and is involved in a huge range of behaviors including camouflage, courtship, communication and hunting. Until now, the earliest dated origin of bioluminescence in animals was thought to be around 267 million years ago in small marine crustaceans called ostracods.
But for a trait that is literally illuminating, bioluminescence's origins have remained shadowy.

Nobody quite knows why it first evolved in animals.
In search of the trait's earliest origins, the researchers decided to peer back into the evolutionary history of the octocorals, an evolutionarily ancient and frequently bioluminescent group of animals that includes soft corals, sea fans and sea pens.

Like hard corals, octocorals are tiny colonial polyps that secrete a framework that becomes their refuge, but unlike their stony relatives, that structure is usually soft. Octocorals that glow typically only do so when bumped or otherwise disturbed, leaving the precise function of their ability to produce light a bit mysterious.
Part 1

Comment by Dr. Krishna Kumari Challa on April 25, 2024 at 11:05am

In a collaboration with Kobus Kuipers of Delft University of Technology, the group indeed demonstrated a similar effect for light in a photonic crystal.

A photonic crystal normally consists of a regular—two dimensional—pattern of holes in a silicon layer. Light can move freely in this material, just like electrons in graphene.
Breaking this regularity in exactly the right manner will deform the array and consequently lock the photons. This is how they create Landau levels for photons.
In Landau levels light waves no longer move; they do not flow through the crystal but stand still. The researchers succeeded in demonstrating this, showing that the deformation of the crystal array has a similar effect on photons as a magnetic field on electrons.

By playing with the deformation pattern, we even managed to establish various types of effective magnetic fields in one material. As a result, photons can move through certain parts of the material but not in others. Hence, these insights also provide new ways to steer light on a chip.
This brings on-chip applications closer.If we can confine light at the nanoscale and bring it to a halt like this, its strength will be enhanced tremendously. And not only at one location, but over the entire crystal surface. Such light concentration is very important in nanophotonic devices, for example for the development of efficient lasers or quantum light sources.

René Barczyk et al, Observation of Landau levels and chiral edge states in photonic crystals through pseudomagnetic fields induced by synthetic strain, Nature Photonics (2024). DOI: 10.1038/s41566-024-01412-3

Part 2

Comment by Dr. Krishna Kumari Challa on April 25, 2024 at 11:02am

Light stands still in a deformed crystal

 AMOLF researchers, in collaboration with Delft University of Technology have succeeded in bringing light waves to a halt by deforming the two-dimensional photonic crystal that contains them. The researchers show that even a subtle deformation can have a substantial effect on photons in the crystal. This resembles the effect that a magnetic field has on electrons.

This principle offers a new approach to slow down light fields and thereby enhance their strength. Realizing this on a chip is particularly important for many applications, say the researchers.

The researchers have published their findings in the journal Nature Photonics. Simultaneously, a research team from Pennsylvania State University has published an article in the same journal about how they demonstrated—independently from the Dutch team—an identical effect.

Manipulating the flow of light in a material at small scales is beneficial for the development of nanophotonic chips. For electrons, such manipulation can be realized using magnetic fields; the Lorentz force steers the motion of electrons. However, this is impossible for photons because they do not have charge.

Researchers in the Photonic Forces group at AMOLF are looking for techniques and materials that would enable them to apply forces to photons that resemble the effects of magnetic fields.

The researchers looked for inspiration at the way in which electrons behave in materials. In a conductor, electrons can in principle move freely, but an external magnetic field can stop this. The circular movement caused by the magnetic field stops conduction and as such electrons can only exist in the material if they have very specific energies. These energy levels are called Landau levels, and they are characteristic for electrons in a magnetic field  

But, in the two-dimensional material graphene—that consists of a single layer of carbon atoms arranged in a crystal—these Landau levels can also be caused by a different mechanism than a magnetic field. In general, graphene is a good electronic conductor, but this changes when the crystal array is deformed, for instance by stretching it like elastics.

"Such mechanical deformation stops conduction; the material turns into an insulator and consequently the electrons are bound to Landau levels. Hence, the deformation of graphene has a similar effect on electrons in a material as a magnetic field, even without a magnet. Researchers asked themselves if a similar approach would also work for photons."
Part 1

Comment by Dr. Krishna Kumari Challa on April 24, 2024 at 11:51am

The authors tested variations of a fast-pulsing laser treatment to achieve the optimal balance of characteristics in the cork that can be achieved at low cost.

They closely examined nanoscopic structural changes and measured the ratio of oxygen and carbon in the material, changes in the angles with which water and oil contact the surface, and the material's light wave absorption, reflection, and emission across the spectrum to determine its durability after multiple cycles of warming and cooling.

The photothermal properties endowed in cork through this laser processing allow the cork to warm quickly in the sun. The deep grooves also increase the surface area exposed to sunlight, so the cork can be warmed by just a little sunlight in 10–15 seconds. This energy is used to heat up spilled oil, lowering its viscosity and making it easier to collect. In experiments, the laser-treated cork collected oil out of water within two minutes.

The laser treatments not only help to better absorb oil, but also work to keep water out.
When the cork undergoes a fast-pulsing laser treatment, its surface microstructure becomes rougher. This micro- to nano-level roughness enhances hydrophobicity.

As a result, the cork collects the oil without absorbing water, so the oil can be extracted from the cork and possibly even reused.

Femtosecond laser structured black superhydrophobic cork for efficient solar-driven cleanup of crude oil, Applied Physics Letters (2024). DOI: 10.1063/5.0199291

Part 2

Comment by Dr. Krishna Kumari Challa on April 24, 2024 at 11:50am

Laser-treated cork absorbs oil for carbon-neutral ocean cleanup

Oil spills are deadly disasters for ocean ecosystems. They can have lasting impacts on fish and marine mammals for decades and wreak havoc on coastal forests, coral reefs, and the surrounding land. Chemical dispersants are often used to break down oil, but they often increase toxicity in the process.

In Applied Physics Letters, researchers  published their work using laser treatments to transform ordinary cork  into a powerful tool for treating oil spills.

They wanted to create a nontoxic, effective oil cleanup solution using materials with a low carbon footprint, but their decision to try cork resulted from a surprising discovery.

In a different laser experiment, they accidentally found that the wettability of the cork processed using a laser changed significantly, gaining superhydrophobic (water-repelling) and superoleophilic (oil-attracting) properties. After appropriately adjusting the processing parameters, the surface of the cork became very dark, which made them realize that it might be an excellent material for photothermal conversion.

Combining these results with the eco-friendly, recyclable advantages of cork, they thought of using it for marine oil spill cleanup.

Cork comes from the bark of cork oak trees, which can live for hundreds of years. These trees can be harvested about every seven years, making cork a renewable material. When the bark is removed, the trees amplify their biological activity to replace it and increase their carbon storage, so harvesting cork helps mitigate carbon emissions. Part 1

Comment by Dr. Krishna Kumari Challa on April 24, 2024 at 11:00am

Researchers detect a new molecule in space

New research has revealed the presence of a previously unknown molecule in space. The open-access paper describing it, "Rotational Spectrum and First Interstellar Detection of 2-Methoxyethanol Using ALMA Observations of NGC 6334I," was published in the April 12 issue of The Astrophysical Journal Letters.

Researchers worked to assemble a puzzle comprised of pieces collected from across the globe, extending beyond MIT to France, Florida, Virginia, and Copenhagen, to achieve this exciting discovery.

To detect new molecules in space, researchers first must have an idea of what molecule they want to look for, then they can record its spectrum in the lab here on Earth, and then finally they look for that spectrum in space using telescopes.

To detect this molecule using radio telescope observations, the group first needed to measure and analyze its rotational spectrum on Earth. The researchers combined experiments from the University of Lille (Lille, France), the New College of Florida (Sarasota, Florida), and the McGuire lab at MIT to measure this spectrum over a broadband region of frequencies ranging from the microwave to sub-millimeter wave regimes (approximately 8 to 500 gigahertz).

The data gleaned from these measurements permitted a search for the molecule using Atacama Large Millimeter/submillimeter Array (ALMA) observations toward two separate star-forming regions: NGC 6334I and IRAS 16293-2422B. Members of the group analyzed these telescope observations alongside researchers at the National Radio Astronomy Observatory (Charlottesville, Virginia) and the University of Copenhagen, Denmark.

Ultimately, they observed 25 rotational lines of 2-methoxyethanol that lined up with the molecular signal observed toward NGC 6334I (the barcode matched), thus resulting in a secure detection of 2-methoxyethanol in this source.This allowed them to then derive physical parameters of the molecule toward NGC 6334I, such as its abundance and excitation temperature. It also enabled an investigation of the possible chemical formation pathways from known interstellar precursors.
Molecular discoveries like this one help the researchers to better understand the development of molecular complexity in space during the star formation process. 2-methoxyethanol, which contains 13 atoms, is quite large for interstellar standards—as of 2021, only six species larger than 13 atoms were detected outside the solar system, many by this research group, and all of them existing as ringed structures.
Continued observations of large molecules and subsequent derivations of their abundances allows scientists to advance our knowledge of how efficiently large molecules can form and by which specific reactions they may be produced.

Zachary T. P. Fried et al, Rotational Spectrum and First Interstellar Detection of 2-methoxyethanol Using ALMA Observations of NGC 6334I, The Astrophysical Journal Letters (2024). DOI: 10.3847/2041-8213/ad37ff

Comment by Dr. Krishna Kumari Challa on April 24, 2024 at 10:05am

There are many lines of evidence. The flat region in the air-side temperature distribution above hot water will be the easiest for people to reproduce. That temperature profile "is a signature" that demonstrates the effect clearly.
It is quite hard to explain how this kind of flat temperature profile comes about without invoking some other mechanism" beyond the accepted theories of thermal evaporation.
The observations in the manuscript points to a new physical mechanism that foundationally alters our thinking on the kinetics of evaporation.

Guangxin Lv et al, Photomolecular effect: Visible light interaction with air–water interface, Proceedings of the National Academy of Sciences (2024). DOI: 10.1073/pnas.2320844121

Part 4

Comment by Dr. Krishna Kumari Challa on April 24, 2024 at 10:03am

researchers have proposed a physical mechanism that can explain the angle and polarization dependence of the effect, showing that the photons of light can impart a net force on water molecules at the water surface that is sufficient to knock them loose from the body of water. But they cannot yet account for the color dependence, which they say will require further study.

They have named this the photomolecular effect, by analogy with the photoelectric effect that was discovered by Heinrich Hertz in 1887 and finally explained by Albert Einstein in 1905. That effect was one of the first demonstrations that light also has particle characteristics, which had major implications in physics and led to a wide variety of applications, including LEDs. Just as the photoelectric effect liberates electrons from atoms in a material in response to being hit by a photon of light, the photomolecular effect shows that photons can liberate entire molecules from a liquid surface, the researchers say.

The finding of evaporation caused by light instead of heat provides new disruptive knowledge of light-water interaction.
It could help us gain new understanding of how sunlight interacts with cloud, fog, oceans, and other natural water bodies to affect weather and climate. It has significant potential practical applications such as high-performance water desalination driven by solar energy.
The finding may solve an 80-year-old mystery in climate science. Measurements of how clouds absorb sunlight have often shown that they are absorbing more sunlight than conventional physics dictates possible. The additional evaporation caused by this effect could account for the longstanding discrepancy, which has been a subject of dispute since such measurements are difficult to make.

Those experiments are based on satellite data and flight data. They fly an airplane on top of and below the clouds, and there are also data based on the ocean temperature and radiation balance. And they all conclude that there is more absorption by clouds than theory could calculate. However, due to the complexity of clouds and the difficulties of making such measurements, researchers have been debating whether such discrepancies are real or not. And what was discovered now suggests that hey, there's another mechanism for cloud absorption, which was not accounted for, and this mechanism might explain the discrepancies.
Part 3

Comment by Dr. Krishna Kumari Challa on April 24, 2024 at 9:59am

The new work builds on research reported* last year, which described this new "photomolecular effect" but only under very specialized conditions: on the surface of specially prepared hydrogels soaked with water. In the new study, the researchers demonstrate that the hydrogel is not necessary for the process; it occurs at any water surface exposed to light, whether it's a flat surface like a body of water or a curved surface like a droplet of cloud vapour.

Because the effect was so unexpected, the team worked to prove its existence with as many different lines of evidence as possible. In this study, they report 14 different kinds of tests and measurements they carried out to establish that water was indeed evaporating—that is, molecules of water were being knocked loose from the water's surface and wafted into the air—due to the light alone, not by heat, which was long assumed to be the only mechanism involved.

One key indicator, which showed up consistently in four different kinds of experiments under different conditions, was that as the water began to evaporate from a test container under visible light, the air temperature measured above the water's surface cooled down and then leveled off, showing that thermal energy was not the driving force behind the effect.

Other key indicators that showed up included the way the evaporation effect varied depending on the angle of the light, the exact color of the light, and its polarization. None of these varying characteristics should happen because at these wavelengths, water hardly absorbs light at all—and yet the researchers observed them.

The effect is strongest when light hits the water surface at an angle of 45 degrees. It is also strongest with a certain type of polarization, called transverse magnetic polarization. And it peaks in green light—which, oddly, is the color for which water is most transparent and thus interacts the least.

* Yaodong Tu et al, Plausible photomolecular effect leading to water evaporation exceeding the thermal limit, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2312751120

Part 2

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