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Comment by Dr. Krishna Kumari Challa on May 29, 2024 at 10:05am

Even the scientists who made the original, possible detection of planet HD 26965 b—almost immediately compared to the fictional Vulcan—cautioned that it could turn out to be messy stellar jitters masquerading as a planet. They reported evidence of a "super-Earth"—larger than Earth, smaller than Neptune—in a 42-day orbit around a sun-like star about 16 light-years away. The new analysis, using high-precision radial velocity measurements not yet available in 2018, confirms that caution about the possible discovery was justified.

The bad news for "Star Trek" fans comes from an instrument known as NEID, a recent addition to the complex of telescopes at Kitt Peak National Observatory. NEID, like other radial velocity instruments, relies on the Doppler effect: shifts in the light spectrum of a star that reveal its wobbling motions. In this case, parsing out the supposed planet signal at various wavelengths of light, emitted from different levels of the star's outer shell (photosphere), revealed significant differences between individual wavelength measurements—their Doppler shifts—and the total signal when they were all combined.

That means, in all likelihood, that the planet signal is really the flickering of something on the star's surface that coincides with a 42-day rotation—perhaps the roiling of hotter and cooler layers beneath the star's surface, called convection, combined with stellar surface features such as spots and "plages," which are bright, active regions. Both can alter a star's radial velocity signals.

The demonstration of such finely tuned radial velocity measurements holds out the promise of making sharper observational distinctions between actual planets and the shakes and rattles on surfaces of distant stars.

Abigail Burrows et al, The Death of Vulcan: NEID Reveals That the Planet Candidate Orbiting HD 26965 Is Stellar Activity*, The Astronomical Journal (2024). DOI: 10.3847/1538-3881/ad34d5

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Comment by Dr. Krishna Kumari Challa on May 29, 2024 at 10:03am

The death of Vulcan: Study reveals planet is actually an astronomical illusion caused by stellar activity

A planet thought to orbit the star 40 Eridani A—host to Mr. Spock's fictional home planet, Vulcan, in the "Star Trek" universe—is really a kind of astronomical illusion caused by the pulses and jitters of the star itself, a new study shows.

A science team led by astronomer Abigail Burrows of Dartmouth College, and previously of NASA's Jet Propulsion Laboratory, has published a paper describing the new result, titled "The death of Vulcan: NEID reveals the planet candidate orbiting HD 26965 is stellar activity," in The Astronomical Journal. (Note: HD 26965 is an alternate designation for the star 40 Eridani A.)

The possible detection of a planet orbiting a star that Star Trek made famous drew excitement and plenty of attention when it was announced in 2018. Only five years later, the planet appeared to be on shaky ground when other researchers questioned whether it was there at all.

Now, precision measurements using a NASA-NSF instrument, installed a few years ago atop Kitt Peak in Arizona, seem to have returned the planet Vulcan even more definitively to the realm of science fiction.

Two methods for detecting exoplanets—planets orbiting other stars—dominate all others in the continuing search for strange new worlds. The transit method, watching for the tiny dip in starlight as a planet crosses the face of its star, is responsible for the vast majority of detections. But the "radial velocity" method also has racked up a healthy share of exoplanet discoveries.

This method is especially important for systems with planets that don't, from Earth's point of view, cross the faces of their stars. By tracking subtle shifts in starlight, scientists can measure "wobbles" in the star itself, as the gravity of an orbiting planet tugs it one way, then another. For very large planets, the radial velocity signal mostly leads to unambiguous planet detections. But not-so-large planets can be problematic.

Part 1

Comment by Dr. Krishna Kumari Challa on May 29, 2024 at 9:32am

What are the causes for landslides ?

Landslides occur due to due to failure of stability of slopes. The following factors cause failure of slopes.

Clay and shale beds are weak materials and tend to get slided particularly in the presence of water.

Groundwater and precipitation – groundwater conditions of the area depends on the geological and hydrological parameters, storage, recharge, , duration of precipitation , intensity of rainfall, lithological characteristics of the area and gradient of slope etc. In general slope stability is adversely affected by rise in groundwater table, resulting in pore water pressure . The shearing resistance of the mineral grains reduces and then this leads to landslides.

Insitu stresses – the stress within the slope rock is generated when load is placed at top of the slope. This may be due to accumulation of rain or snow water or human activities such as stock piling of ore deposits, waste deposits, mine tailings, buildings and removal of natural rocks for construction or foundation works.

Textures – anisotrophy in fabric is the weakest internal structure of a rock and it facilitates movement of the rock mass. Uniform or medium grained mineral content of rock bears a greater strength than that borne by rocks of unequal grains.

Weak planes- Schistocity, slaty structure and lamination are weak points . It has been observed that massive slides tales place in sedimentary rocks inter bedded with limestones and shales.

Weathering weakens the physical and chemical bonding in rocks and this leads to failure of mass even in hard rocks.

Structural features

Bedding planes, fractures, joints, faults , fissures and schistocity will have influence on downward slope of rock mass. In nature no rock mass is truly continuous. It will be broken by fracture, joints, bedding planes, dykes, and veins. These discontinuities will lead to instability of strata.

Seismic activity – travel of elastic waves released during an earthquake in the ground increase the shear stress in the slope and consequently decrease volume open spaces within the rock material there by increasing the pressure of water in void space and leads to failure of rock mass.

Part 3

Comment by Dr. Krishna Kumari Challa on May 29, 2024 at 9:30am

So what would it take to warn people of a coming landslide? You would need a prediction for earthquakes and rainfall, in addition to a perfect knowledge of the slope-forming geomaterial.

Under our feet, geomaterials may include multiple, entangled layers of various kinds of rocks and particulate materials, such as sand, silt and clays. Their strength varies from a factor of one to 1,000, and their spatial distribution dictates where the slope is likely to fail.

To accurately assess the stability of the slope, a three-dimensional mapping of these materials and their strengths is needed. No sensor can provide this information, so geologists and geotechnical engineers must deal with partial information obtained at a few selected locations and extrapolate this data to the rest of the slope.

The weakest link of the chain—such as an existing fracture in a rock mass—is easily missed. This is an inevitable source of uncertainty when trying to predict how much material might slip. We do know that the larger the volume of a landslide, the farther its runout distance. But it's hard to gauge the exact size of a landslide, making predictions of runout distances and safe zones uncertain. The question of "when will a landslide will occur" is also uncertain. Mechanical analysis enables us to estimate the vulnerability of a slope in a particular scenario, including earthquake magnitude and distribution of groundwater. But predicting if and when these triggers will happen is as "easy" as predicting the weather and seismic activity—a difficult task. Unfortunately, all the money in the world can't buy accurate landslide predictions—especially in remote parts of the world.

https://theconversation.com/what-causes-landslides-can-we-predict-t...

Part 2

Comment by Dr. Krishna Kumari Challa on May 29, 2024 at 9:29am

What causes landslides? 

Landslides happen when the pull from gravity exceeds the strength of the geomaterial forming the slope of a hill or mountain. Geomaterials can be as varied as rocks, sand, silt and clays.

Then, part of this slope starts sliding downhill. Depending on where the slope fails, the material sliding down can be just a few cubic meters or a few million cubic meters in volume.

Why do slopes fail? Most natural landslides are triggered by earthquakes or rainfall, or a combination of both.

Earthquakes shake the ground, stress it and weaken it over time. Rainwater can seep through the ground and soak it—the ground is often porous like a sponge—and add weight to the slope. This is why PNG is so prone to landslides, as it sits on an active fault and is subjected to heavy rainfalls.

Another adverse effect of water is erosion: the constant action of waves undercuts coastal slopes, causing them to fail. Groundwater can also dissolve rocks within slopes.

Humans can (and do) cause landslides in several ways, too. For example, deforestation has a negative impact on slope stability, as tree roots naturally reinforce the ground and drain water out. Also, mine blasts produce small earthquake-like ground vibrations that shake slopes nearby.

It's very difficult to predict and mitigate landslide risk effectively.

Part 1

Comment by Dr. Krishna Kumari Challa on May 29, 2024 at 9:24am

Study suggests 'biodegradable' teabags don't readily deteriorate in the environment

Some teabags manufactured using plastic alternatives do not degrade in soil and have the potential to harm terrestrial species, a new study has shown.

The research looked at commonly available teabags made using three different compositions of polylactic acid (PLA), which is derived from sources such as corn starch or sugar cane.

The teabags were buried in soil for seven months, and a range of techniques were then used to assess whether—and to what extent—they had deteriorated.

The results showed that teabags made solely from PLA remained completely intact. However, the two types of teabags made from a combination of cellulose and PLA broke down into smaller pieces, losing between 60% and 80% of their overall mass and with the PLA component remaining.

The study also examined the impacts of the disks cut from the teabags on a species of earthworm, Eisenia fetida, which has a critical role in soil nutrient turnover as it consumes organic matter.

Researchers found that being exposed to three different concentrations of teabag disks—equivalent to the mass of half, one and two teabags—resulted in up to 15% greater mortality, while some concentrations of PLA had a detrimental effect on earthworm reproduction.

Writing in the journal Science of the Total Environment, the study's authors highlight the need for accurate disposal information to be clearly displayed on product packaging.

Only one of the manufacturers whose products were chosen for the study indicated on the packaging that the teabags were not home compostable.

This could lead to them ending up in soil, while there is also high potential for consumer confusion about the meaning of terms such as plant-based or biodegradable, emphasizing the need for clear guidance on appropriate disposal.

W. Courtene-Jones et al, Deterioration of bio-based polylactic acid plastic teabags under environmental conditions and their associated effects on earthworms, Science of The Total Environment (2024). DOI: 10.1016/j.scitotenv.2024.172806

Comment by Dr. Krishna Kumari Challa on May 29, 2024 at 9:17am

Because nanoparticles are so small, it's impossible to see them using conventional microscopes. Therefore, the researchers tagged the nanoparticles with either fluorescence or europium, a rare metal that is not naturally present in the human body.

They  found that the nanoplastics can cross blood vessel walls, and that they accumulated to relatively high levels in the heart, liver and kidneys. Some nanoplastics were excreted by the kidneys.

Interestingly, the researchers also found nanoplastics in the avascular heart cushions: a type of heart tissue without blood vessels. They think the nanoplastics might enter the heart through the fenestrate. These are small openings within the developing heart tissue that play a role in the formation and remodeling of the heart's structure during development. These fenestrations are temporary structures that typically close as the heart matures.

Now we know how these nanoplastics spread, we can start investigating the health risks.

There is already research linking nanoparticles to a higher risk of heart attacks and strokes. Especially during the developmental stage, nanoparticles could potentially be quite dangerous.

We now understand that we shouldn't administer nanomedicines to pregnant women indiscriminately, as there is a risk that nanoparticles could reach and affect the developing organs of their babies.

Meiru Wang et al, The biodistribution of polystyrene nanoparticles administered intravenously in the chicken embryo, Environment International (2024). DOI: 10.1016/j.envint.2024.108723

Part 2

Comment by Dr. Krishna Kumari Challa on May 29, 2024 at 9:13am

Biologists find nanoplastics in developing chicken heart

Nanoplastics can accumulate in developing hearts, according to a study published in Environment International by biologists. Research on chicken embryos sheds new light on how these tiny plastic particles pose a threat to our health.

Disposable cups, plastic bags and packaging material: Plastics exposed to the elements become brittle over time, and start shedding small particles from their surface into nature. These particles can be as tiny as only a few nanometers in size.

You can find these nanoplastics everywhere now: in the sea, in the soil, in the food chain… and in our blood.   They have even been found in human placentas.

This made scientists think: What happens when those nanoplastics end up in the blood of the embryo?

During an earlier study, investigators discovered that a high concentration of nanoplastics can cause malformations in the heart, eyes, and nervous systems of chicken embryos. But for a more complete understanding of the toxicity of nanoplastics, they first need more information about how they spread from the blood throughout the rest of the body.

That knowledge will also be informative in nanomedicine, where scientists aim to use nanoplastics (and other nanoparticles) as vehicles for drug-delivery.

Researchers administered polystyrene nanoparticles directly into the bloodstream of chicken embryos. Chicken embryos are a widely used model for research on growth and development. In mammals, it's much more challenging to administer substances or take measurements because their embryos develop inside the mother's womb.

Part 1

Comment by Dr. Krishna Kumari Challa on May 29, 2024 at 9:06am

Green chemistry: Producing gold nano-particles (and hydrogen) in water without the need for toxic chemicals

In a surprise discovery, Flinders University nanotechnology researchers have produced a range of different types of gold nanoparticles by adjusting water flow in the novel vortex fluidic device—without the need for toxic chemicals. The article, "Nanogold Foundry Involving High-Shear-Mediated Photocontact Electri...," has been published in Small Science.

The green chemistry lab work on nano gold formation also led to the discovery of a contact electrification reaction in water in the device—which resulted in the generation of hydrogen and hydrogen peroxide.

In their study scientists collaborated on the developing size and form of gold nanoparticles from various VFD processing parameters and concentrations of gold chloride solution.

Through this research, they have discovered a new phenomenon in the vortex fluidic device. The photo-contact electrification process at the solid-liquid interface which could be used in other chemical and biological reactions.

They also have achieved synthesis of pure, pristine gold nanoparticles in water in the VFD, without the use of chemicals commonly used—and thus minimizing waste.

This method is significant for the formation of nanomaterials in general because it is a green process, quick, scalable and yields nanoparticles with new properties.

Gold nanoparticles' size and shape are critical for a range of applications—from drug delivery to catalysis, sensing and electronics—due to their physical, chemical and optical properties.

The vortex fluidic device, devised a decade ago is a rapidly rotating tube open at one end with liquids delivered through jet feeds. Different rotational speeds and external application of light in the device can be used to synthesize particles to specification.

Researchers around the world are now finding the continuous flow, thin film fluidic device useful in exploring and optimizing more sustainable nano-scale processing techniques.

In this latest experiment, the researchers hypothesize that the high shear regimes of the VFD led to the quantum mechanical effect known as contact electrification, which is another exciting development.

Badriah M. Alotaibi et al, Nanogold Foundry Involving High‐Shear‐Mediated Photocontact Electrification in Water, Small Science (2024). DOI: 10.1002/smsc.202300312

Comment by Dr. Krishna Kumari Challa on May 29, 2024 at 8:57am

IL-21 plays a crucial role in the formation of bone marrow plasma cells. Cells formed in IL-21-dependent follicular germinal centers have low CD19 expression, while those from IL-21-independent extrafollicular reactions have high CD19 levels.

Primary immune responses produce both CD19low and CD19high BMPCs, but secondary responses mainly create CD19high cells from reactivated memory B cells in extrafollicular sites. This finding is important for understanding how long-term immunity is maintained and how previous immune responses can impact the effectiveness of future vaccinations.

The rapid extrafollicular immune responses in tissues, like the bone marrow itself, are especially crucial for responding to emerging variants quickly. This research could help optimize vaccination strategies for better long-term protection.

Marta Ferreira-Gomes et al, Recruitment of plasma cells from IL-21-dependent and IL-21-independent immune reactions to the bone marrow, Nature Communications (2024). DOI: 10.1038/s41467-024-48570-0

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