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Comment by Dr. Krishna Kumari Challa on February 22, 2024 at 12:20pm

Button batteries pose 'deadly' risk to toddlers

Comment by Dr. Krishna Kumari Challa on February 22, 2024 at 7:35am

Scientists invent ultra-thin, minimally-invasive pacemaker controlled by light

Millions of people around the world rely on pacemakers—small devices that regulate the electrical impulses of the heart in order to keep it beating smoothly. But to reduce complications, researchers would like to make these devices even smaller and less intrusive.

A team of researchers  has developed a wireless device, powered by light, that can be implanted to regulate cardiovascular or neural activity in the body. The featherlight membranes, thinner than human hair, can be inserted with minimally invasive surgery and contain no moving parts.

Published Feb. 21 in Nature, the results could help reduce complications in heart surgery and offer new horizons for future devices.

Bozhi Tian, Monolithic silicon for high-spatiotemporal translational photostimulation, Nature (2024). DOI: 10.1038/s41586-024-07016-9. www.nature.com/articles/s41586-024-07016-9

Comment by Dr. Krishna Kumari Challa on February 22, 2024 at 7:28am

Electrons become fractions of themselves in graphene, study finds

The electron is the basic unit of electricity, as it carries a single negative charge. This is what we're taught in high school physics, and it is overwhelmingly the case in most materials in nature.

But in very special states of matter, electrons can splinter into fractions of their whole. This phenomenon, known as "fractional charge," is exceedingly rare, and if it can be corralled and controlled, the exotic electronic state could help to build resilient, fault-tolerant quantum computers.

To date, this effect, known to physicists as the "fractional quantum Hall effect," has been observed a handful of times, and mostly under very high, carefully maintained magnetic fields. Only recently have scientists seen the effect in a material that did not require such powerful magnetic manipulation.

Now, physicists have observed the elusive fractional charge effect, this time in a simpler material: five layers of graphene—an atom-thin layer of carbon that stems from graphite and common pencil lead. They report their results in Nature.

The fractional quantum Hall effect is an example of the weird phenomena that can arise when particles shift from behaving as individual units to acting together as a whole. This collective "correlated" behavior emerges in special states, for instance when electrons are slowed from their normally frenetic pace to a crawl that enables the particles to sense each other and interact. These interactions can produce rare electronic states, such as the seemingly unorthodox splitting of an electron's charge.

Researchers found that when five sheets of graphene are stacked like steps on a staircase, the resulting structure inherently provides just the right conditions for electrons to pass through as fractions of their total charge, with no need for any external magnetic field.

The results are the first evidence of the "fractional quantum anomalous Hall effect" (the term "anomalous" refers to the absence of a magnetic field) in crystalline graphene, a material that physicists did not expect to exhibit this effect.

 Long Ju, Fractional quantum anomalous Hall effect in multilayer graphene, Nature (2024). DOI: 10.1038/s41586-023-07010-7. www.nature.com/articles/s41586-023-07010-7

Comment by Dr. Krishna Kumari Challa on February 22, 2024 at 7:23am

Neanderthals' usage of complex adhesives reveals higher cognitive abilities, scientists discover

Neanderthals created stone tools held together by a multi-component adhesive, a team of scientists has discovered. Its findings, which are the earliest evidence of a complex adhesive in Europe, suggest these predecessors to modern humans had a higher level of cognition and cultural development than previously thought.

These astonishingly well-preserved tools showcase a technical solution broadly similar to examples of tools made by early modern humans in Africa, but the exact recipe reflects a Neanderthal 'spin,' which is the production of grips for handheld tools.

The researchers discovered traces of a mixture of ocher and bitumen on several stone tools, such as scrapers, flakes, and blades. Ocher is a naturally occurring earth pigment; bitumen is a component of asphalt and can be produced from crude oil, but also occurs naturally in the soil.

Overall, the development of adhesives and their use in the manufacture of tools is considered to be some of the best material evidence of the cultural evolution and cognitive abilities of early humans. Compound adhesives are considered to be among the first expressions of the modern cognitive processes that are still active today.

 Patrick Schmidt, Ochre-based compound adhesives at the Mousterian type-site document complex cognition and high investment, Science Advances (2024). DOI: 10.1126/sciadv.adl0822. www.science.org/doi/10.1126/sciadv.adl0822

Comment by Dr. Krishna Kumari Challa on February 21, 2024 at 10:59am

Decimal point is older than thought
The decimal point was invented by Italian merchant and astronomer Giovanni Bianchini some 150 years before what was considered to be its first appearance. “I remember running up and down the hallways of the dorm with my computer trying to find anybody who was awake, shouting ‘look at this, this guy is doing decimal points in the 1440s!’” recalls historian Glen Van Brummelen, who discovered Bianchini’s number “with a dot in the middle” while teaching at a maths camp for kids. Bianchini’s training in economics might have given him a perspective different to that of his astronomer peers — who would have exclusively been using the sexagesimal (base 60) system — and his approach was perhaps too revolutionary to catch on until much later.

https://www.nature.com/articles/d41586-024-00473-2?utm_source=Live+...

https://www.sciencedirect.com/science/article/pii/S0315086024000016...

Comment by Dr. Krishna Kumari Challa on February 21, 2024 at 10:10am

Electrons with the 'wrong' spin are filtered out
Using scanning tunneling microscopy, the researchers were also able to solve another mystery, as they reported in the journal Small in November 2023. Electron transport—i.e. electric current—also depends on the combination of molecular handedness and magnetization of the surface.

Depending on the handedness of the bound molecule, electrons with one direction of spin preferentially flow—or "tunnel"—through the molecule, meaning that electrons with the "wrong" spin are filtered out. This chirality-induced spin selectivity had already been observed in earlier studies, but it remained unclear whether an ensemble of molecules is necessary for this or whether individual molecules also exhibit this effect.
The researchers think that these findings eventually cannot fully answer the question of the chirality of life.
However, they can imagine that in certain surface-catalyzed chemical reactions—such as those that could have taken place in the chemical "primordial soup" on the early Earth—a certain combination of electric and magnetic fields could have led to a steady accumulation of one form or another of the various biomolecules—and thus ultimately to the handedness of life.

Mohammad Reza Safari et al, Enantioselective Adsorption on Magnetic Surfaces, Advanced Materials (2023). DOI: 10.1002/adma.202308666

Part 3

Comment by Dr. Krishna Kumari Challa on February 21, 2024 at 10:06am

Mirror images prefer opposing magnetic fields: And this is indeed the case, as a team of researchers reported in the journal Advanced Materials.

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The team coated a (non-magnetic) copper surface with small, ultra-thin "islands" of magnetic cobalt and determined the direction of the magnetic field in these using spin-polarized scanning tunneling microscopy; as mentioned before, this can run in two different directions perpendicular to the metal surface: North up or South up. They then deposited spiral-shaped chiral molecules—a 1:1 mixture of left- and right-handed heptahelicene molecules—onto these cobalt islands in ultrahigh vacuum.

Then they "simply" counted the number of right- and left-handed helicene molecules on the differently magnetized cobalt islands, almost 800 molecules in total, again using scanning tunneling microscopy. And lo and behold: Depending on the direction of magnetic field, one or the other form of the helicene spirals had settled preferentially.

Moreover, the experiments showed that the selection—the preference for one or the other enantiomer—not only occurs during the binding on the cobalt islands, but already beforehand.

Before the molecules take up their final (preferred) position on one of the cobalt islands, they migrate long distances across the copper surface in a significantly weaker bound precursor state in "search" for an ideal position. They are only bound to the surface by so-called van der Waals forces. These are merely caused by fluctuations in the electronic shell of atoms and molecules and are therefore relatively weak. The fact that even these are influenced by magnetism, i.e. the direction of rotation (spin) of the electrons, was not known thus far.

Part 2

Comment by Dr. Krishna Kumari Challa on February 21, 2024 at 10:04am

Magnetic effects at the origin of life? It's the spin that makes the difference

Biomolecules such as amino acids and sugars occur in two mirror-image forms—in all living organisms, however, only one is ever found. Why this is the case is still unclear. Researchers  have now found evidence that the interplay between electric and magnetic fields could be at the origin of this phenomenon.

The so-called homochirality of life—the fact that all biomolecules in living organisms only ever occur in one of two mirror-image forms—has puzzled a number of scientific luminaries, from the discoverer of molecular chirality, Louis Pasteur, to William Thomson (Lord Kelvin) and Nobel Prize winner Pierre Curie. A conclusive explanation is still lacking, as both forms have, for instance, the same chemical stability and do not differ from each other in their physicochemical properties. The hypothesis, however, that the interplay between electric and magnetic fields could explain the preference for one or the other mirror-image form of a molecule—so-called enantiomers—emerged early on.

It was only a few years ago, though, that the first indirect evidence emerged that the various combinations of these force fields can indeed "distinguish" between the two mirror images of a molecule. This was achieved by studying the interaction of chiral molecules with metallic surfaces that exhibit a strong electric field over short distances.
The surfaces of magnetic metals such as iron, cobalt or nickel thus allow electric and magnetic fields to be combined in various ways—the direction of magnetization is simply reversed, from "North up—South down" to "South up—North down."

If the interplay between magnetism and electric fields actually triggers "enantioselective" effects, then the strength of the interaction between chiral molecules and magnetic surfaces should also differ, for example—depending on whether a right-handed or left-handed molecule "settles" on the surface.
Part 1

Comment by Dr. Krishna Kumari Challa on February 20, 2024 at 10:55am

The rotation process fails in about 1 in 500 human births, resulting in a displacement of the bowel known as intestinal malrotation. This malrotation can lead to severe complications, such as bowel obstructions from the intestine looping around itself, requiring surgery in early infancy.
Researchers zeroed in on atrazine as a potential cause after it had been discovered that the herbicide dramatically increased the frequency of intestinal rotation in the wrong direction in lab experiments on frogs.
Atrazine is one of the most widely used agricultural herbicides in several countries, although it is banned in some now.

Exposure to atrazine under laboratory conditions caused a metabolic imbalance in frog embryos that prevented cells from properly dividing, growing, or rearranging themselves, which disrupted several cellular processes in the gut. It became harder for the tissues to stretch normally, which made the gut tube shorter.

"The resultant decreased length of the gut tube consequently prevents the crucial hairpin loop of the intestine from achieving its normal anatomical position, compelling the intestine to coil in a reversed orientation," the study authors write.

According to the team, these gut development issues seem to stem from the fact that atrazine throws the body's redox reactions off balance. Imbalances between a cell's oxidants and antioxidants can play a role in diseases. Treating the frogs with antioxidants before they were exposed to atrazine prevented their guts from twisting the wrong way.

It's important to note that the frog embryos were exposed to 1,000 times the levels normally found in the environment, and these results don't prove that exposure to atrazine causes malrotation in humans.

That said, the findings emphasize the importance of metabolic pathways in gut development and highlight possible causes of intestinal malrotation, though there's a lot more to learn.

https://journals.biologists.com/dev/article/151/4/dev202020/343079/...

Part 2

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Comment by Dr. Krishna Kumari Challa on February 20, 2024 at 10:48am

Some Babies Are Born With Twisted Insides: here is the reason

Scientists have identified a possible cause for intestinal malrotation; a common but poorly understood condition present at birth in which the gut doesn't rotate properly during development.

Researchers found that exposure to the herbicide atrazine can disrupt gut rotation development in frog embryos, whose guts develop similarly to humans.

Because frog embryos develop in only a few days and are highly experimentally accessible, they allow us to quickly test new hypotheses about how and why development goes awry during malrotation.

During the development of the digestive system, the gut tube of vertebrates grows a lot longer. This extra length fits inside the body's relatively small space because of a process called intestinal rotation, that winds the 'tube' tightly into a compact coil.

In humans this rotation is thought to result from a revolution in the embryonic intestinal tract, though the precise mechanism remains unknown.

As vertebrates, frogs and humans share a common ancestor and have many similar anatomical features, including an intestine that rotates in a counter-clockwise direction.
part 1

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