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Comment by Dr. Krishna Kumari Challa on November 10, 2021 at 11:42am

Modified silk cloth keeps skin cooler than cotton

A team of researchers has developed a modified textile that can keep skin cooler than materials made of cotton. In their paper published in the journal Nature Nanotechnology, the group describes their approach to developing garments that are cooler when worn in outdoor conditions.

The researchers noted that silk does a good job of reflecting sunlight in the mid-infrared range, which suggests it could be suitable as a cooling garment material. But because it is made by spiders, it contains a protein component that tends to absorb ultraviolet radiation, making the material and its wearer grow hotter under direct sunlight.

To make the silk material UV reflective, the researchers dipped a standard piece of silk fabric into a liquid solution containing highly refractive inorganic oxide nanoparticles. These adhered to the silk fabric, allowing it to become evenly saturated throughout the material. They allowed the fabric to dry and then tested it to see if the addition of the nanoparticles made the material more UV reflective. They found that under peak sunlight conditions, the temperature under the material was approximately 3.5 degrees Celsius cooler than the ambient air temperature. Next, they placed the material on a patch of simulated skin and found the skin temperature was approximately 8 degrees Celsius cooler than the same type of simulated skin without the material covering. They also found that it kept the artificial skin approximately 12.5 degrees Celsius cooler than standard cotton material. Further testing showed that the material was able to reflect approximately 95% of sunlight, preventing it from passing through to the skin underneath.

Bin Zhu et al, Subambient daytime radiative cooling textile based on nanoprocessed silk, Nature Nanotechnology (2021). DOI: 10.1038/s41565-021-00987-0

https://phys.org/news/2021-11-silk-skin-cooler-cotton.html?utm_sour...

Comment by Dr. Krishna Kumari Challa on November 10, 2021 at 11:28am

How are epilepsy and autism linked?

Epilepsy and autism spectrum disorders, or ASD, show a remarkable degree of comorbidity and may share pathological mechanisms. Questions that have bogged down scientists about these disorders include: Does autism lead to an increase in epilepsy? Or does epilepsy alter the brain circuit, which then leads to autism?

One hypothesis is that during brain development, inhibitory neurons,  which regulate brain rhythms, develop in an abnormal manner. If this is true, then how the brain circuit gets set up is abnormal, which may lead to both autism and epilepsy. 

unlike excitatory neurons that lead to a forward propagation of information, inhibitory neurons work like a brake by suppressing and sculpting the activity of downstream neurons.

The researchers generated mice with a global mutation in all cells that prevented the inhibitory neurons from migrating to their normal location in mature brain circuits. Not surprisingly, they found a reduction in inhibitory currents in the hippocampus, a region of the brain known for memory function. Notably, the mutant mice showed behavioral traits associated with ASD and were more prone to seizures.

Results of the study suggest that a common underlying defect in circuit formation could contribute to both ASD and epilepsy.

Carol Eisenberg et al, Reduced hippocampal inhibition and enhanced autism-epilepsy comorbidity in mice lacking neuropilin 2, Translational Psychiatry (2021). DOI: 10.1038/s41398-021-01655-6

https://medicalxpress.com/news/2021-11-epilepsy-autism-linked.html?...

Comment by Dr. Krishna Kumari Challa on November 10, 2021 at 8:11am

We don’t ‘believe in’ Newton’s laws. We trust them and accepted them because there is genuine evidence that they work.

Newton's laws of motion are three laws of classical mechanics that describe the relationship between the motion of an object and the forces acting on it. These laws can be paraphrased as follows (1):

Law 1. A body continues in its state of rest, or in uniform motion in a straight line, unless acted upon by a force.

Law 2. A body acted upon by a force moves in such a manner that the time rate of change of momentum equals the force.

Law 3. If two bodies exert forces on each other, these forces are equal in magnitude and opposite in direction.

Newton's laws were verified by experiment and observation for over 200 years, and they are excellent approximations at the scales and speeds of everyday life. 

1. https://en.wikipedia.org/wiki/Newton%27s_laws_of_motion

Comment by Dr. Krishna Kumari Challa on November 9, 2021 at 8:12am

Why teapots always drip

The "teapot effect" has been threatening spotless white tablecloths for ages: if a liquid is poured out of a teapot too slowly, then the flow of liquid sometimes does not detach itself from the teapot, finding its way into the cup, but dribbles down at the outside of the teapot.

This phenomenon has been studied scientifically for decades—now a research team  has succeeded in describing the "teapot effect" completely and in detail with an elaborate theoretical analysis and numerous experiments: An interplay of different forces keeps a tiny amount of liquid directly at the edge, and this is sufficient to redirect the flow of liquid under certain conditions.

The "teapot effect" was first described by Markus Reiner in 1956.

So rheology is the science of flow behavior. Again and again, scientists have tried to explain this effect precisely. Although this is a very common and seemingly simple effect, it is remarkably difficult to explain it exactly within the framework of fluid mechanics. 

The sharp edge on the underside of the teapot beak plays the most important role: a drop forms, the area directly below the edge always remains wet. The size of this drop depends on the speed at which the liquid flows out of the teapot. If the speed is lower than a critical threshold, this drop can direct the entire flow around the edge and dribbles down on the outside wall of the teapot.

Researchers  have now succeeded for the first time in providing a complete theoretical explanation of why this drop forms and why the underside of the edge always remains wetted. 

 The mathematics behind it is complicated—it is an interplay of inertia, viscous and capillary forces. The inertial force ensures that the fluid tends to maintain its original direction, while the capillary forces slow the fluid down right at the beak. The interaction of these forces is the basis of the teapot effect. However, the capillary forces ensure that the effect only starts at a very specific contact angle between the wall and the liquid surface. The smaller this angle is or the more hydrophilic (i.e. wettable) the material of the teapot is, the more the detachment of the liquid from the teapot is slowed down.

Interestingly, the strength of gravity in relation to the other forces that occur does not play a decisive role. Gravity merely determines the direction in which the jet is directed, but its strength is not decisive for the teapot effect. The teapot effect would therefore also be observed when drinking tea on a moon base, but not on a space station with no gravity at all.

B. Scheichl et al, Developed liquid film passing a smoothed and wedge-shaped trailing edge: small-scale analysis and the 'teapot effect' at large Reynolds numbers, Journal of Fluid Mechanics (2021). DOI: 10.1017/jfm.2021.612

https://phys.org/news/2021-11-teapots.html?utm_source=nwletter&...

Comment by Dr. Krishna Kumari Challa on November 8, 2021 at 11:43am

Comment by Dr. Krishna Kumari Challa on November 8, 2021 at 8:17am

Why Arthritis Keeps Flaring Up in The Same Joints

According to new research conducted on mice, this could be because our immune system keeps a record of these past afflictions, creating a personalized disease pattern in each individual. Understanding more about how and why this happens could open up new opportunities for treating the disorder.

This latest study zooms in on the T cells in mice's bodies, white blood cells that are key to the immune system. In particular, the T cells in the synovium – the tissue lining the inside of the capsule around each joint – appear to hold a memory of previous RA problems.

Overwhelmingly, flares occur in a previously involved joint. The study shows that  these T cells anchor themselves in the joints and stick around indefinitely after the flare is over, waiting for another trigger. If you delete these cells, arthritis flares stop.

This was demonstrated through two mouse models using chemical triggers to cause joint inflammation and one mouse model using a genetic trigger to generate the same effect: The researchers removed a protein that blocked the pro-inflammatory cytokine IL-1.

These triggers caused T cells to rally other cells to the immunity cause, leading to arthritis flare-ups in specific joints in the mice. When these T cells were taken out, additional inflammation was prevented. These T cells don't move between joints and take up "long-term residency" where they are, the researchers say, ready to be reactivated again.

The approach taken here was actually inspired by skin studies. T cells with a form of memory are known to reside in the skin, leading to repeating patterns in skin problems such as psoriasis. It also happens with reactions to nickel in jewelry or wristwatches.

The research team thinks that other types of autoimmune arthritis could work in the same way, which could lead to better treatments and approaches to these issues. The next step is to confirm that the same process happens in humans and find out ways to target it.

https://www.cell.com/cell-reports/fulltext/S2211-1247(21)01372-3

https://www.sciencealert.com/immune-system-memory-might-explain-why...

Comment by Dr. Krishna Kumari Challa on November 8, 2021 at 6:54am

Dr. Kamal Ranadive’s 104th BirthdayToday’s (google's) Doodle celebrates Indian cell biologist Dr. Kamal Ranadive, who is best known for her groundbreaking cancer research and devotion to creating a more equitable society through science and education.

Kamal Ranadive was an Indian biomedical researcher who is known for her research in cancer about the links between cancers and viruses. She was a founder member of the Indian Women Scientists' Association.

Comment by Dr. Krishna Kumari Challa on November 7, 2021 at 12:08pm

How bacteria can clean up oil spills too 

Bacteria are often painted as our adversaries, but when it comes to oil spills, toxic chemicals, and radioactive waste, they could be what save us from ourselves.

Comment by Dr. Krishna Kumari Challa on November 6, 2021 at 9:34am

Another expected differentiator affecting micro-fracture propagation in human skeletons is bone density, which decreases with age after people reach about 40 years of age, and which might be susceptible to greater amounts of lightning-induced fracturing due to bones being more brittle.

According to the researchers, a two-fold mechanism explains why the micro-fractures in bones form the way they do.

"Firstly, the current itself produces a high-pressure shock wave when traveling through the bone," members of the research team explain in an article written for The Conversation.

"Lightning specialists term this barotrauma: the passage of electrical energy literally blows bone cells apart."

The second mechanism is an example of the piezoelectric effect, affecting how bone behaves when it's in an electric field.

"Collagen, the organic part of bone, is arranged as fibers or fibrils," the researchers explain.

"These fibrils rearrange themselves when a current is applied, causing stress to build up in the mineralized and crystallized component of bone, in turn leading to deformation and cracking."

For forensic pathologists, the discovery of the micro-fracture patterns could indeed be a "smoking gun", indicating the probable cause of death in mysterious fatalities where no other evidence remains.

For the rest of us, if we want to avoid sustaining these microscopic ruptures ourselves, it's best to stay inside whenever the weather looks like it could turn deadly.

After all, even if lightning (almost) never strikes twice, it often only needs once.

The findings are reported in Forensic Science International: Synergy.

https://www.sciencealert.com/lightning-strikes-carve-a-deadly-signa...

part 2

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Comment by Dr. Krishna Kumari Challa on November 6, 2021 at 9:33am

Lightning Strikes Carve a Deadly Signature Deep Inside The Bones, Scientists Discover

When a body is struck by lightning, a lot of different things happen. For those who do not survive the ordeal, a range of physical evidence is left on their bodies that can identify the cause of death: damage to the skin, including sometimes burn marks, as well as trauma to various organs.

But what if all the tissue decomposes? From the standpoint of forensic scientists who may only have bones to work with, does lightning leave any discernible trace behind on a skeleton?

According to a new study, yes it does.

In previous experiments, Bacci and fellow researchers identified these unique markers in animal bones, noting "extensive micro-fracturing and fragmentation of the bone matrix" in pig bones subjected to high impulse current, simulating the electrical jolt of a lightning bolt.

In that study, the same kind of micro-fracturing was also seen in the bones of a wild giraffe that was killed by a lightning strike, but it remained unclear whether human skeletons exposed to lightning-levels of current would reveal the same gruesome signature.

With the aid of cadavers donated to science, we now have our answer, with the researchers observing similar patterns of micro-fracturing in human bone subjected to the current application, and of a kind that's distinct from purely thermally induced changes to bone (such as bones burnt in a fire).

"[The lightning damage] takes the form of cracks which radiate out from the center of bone cells, or which jump irregularly between clusters of cells. The pattern of trauma is identical even though the micro-structure of human bone is different from animal bone.

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