Comment

Comment by Dr. Krishna Kumari Challa on May 19, 2021 at 7:12am

Scientists debut most efficient 'optical rectennas,' devices that harvest power from heat

Scientists have tapped into a unique property of electrons to design devices that can capture excess heat from their environment—and turn it into usable electricity.

The researchers have described their new "optical rectennas" in a paper published recently in the journal Nature Communications. These devices, which are too small to see with the naked eye, are roughly 100 times more efficient than similar tools used for energy harvesting. And they achieve that feat through a mysterious process called "resonant tunneling"—in which electrons pass through solid matter without spending any energy.

Rectennas (short for "rectifying antennas") work a bit like car radio antennas. But instead of picking up radio waves and turning them into tunes, optical rectennas absorb light and heat and convert it into power.

They're also potential game changers in the world of renewable energy. Working rectennas could, theoretically, harvest the heat coming from factory smokestacks or bakery ovens that would otherwise go to waste. Some scientists have even proposed mounting these devices on airships that would fly high above the planet's surface to capture the energy radiating from Earth to outer space.

But, so far, rectennas haven't been able to reach the efficiencies needed to meet those goals. Until now, perhaps. In the new study, researchers have designed the first-ever rectennas that are capable of generating power.

Scientists demonstrate for the first time electrons undergoing resonant tunneling in an energy-harvesting optical rectenna. Until now, it was only a theoretical possibility.

 Nature Communications (2021). DOI: 10.1038/s41467-021-23182-0

https://techxplore.com/news/2021-05-scientists-debut-efficient-opti...

Comment by Dr. Krishna Kumari Challa on May 19, 2021 at 6:55am

Comment by Dr. Krishna Kumari Challa on May 18, 2021 at 11:40am

Scientists construct first-ever synthetic DNA-like polymer

Double helical covalent polymers—which are spiraling collections of nature's building blocks—are fundamental to life itself, and yet, despite decades of research, scientists have never been able to synthesize them in their entirety like their non-helical brethren—until now.

have cracked the code, creating synthetic versions of these large DNA-like molecules for the first time. Using dynamic covalent chemistry, which is a chemistry tool pioneered by these researchers that focuses on reversible bonding interactions with self-correction capabilities, they were able to not only construct a helical covalent polymer that rivals the sophistication of those found in nature but confirm its existence with absolute certainty using single crystal X-ray diffraction (a powerful, non-destructive way to characterize single crystals using light).

Previously, scientists have only been able to solve individual parts of the puzzle. This new discovery out last week in Nature Chemistry, though, completes it, potentially opening this critical and understudied field to new research that could have implications on everything from artificial enzyme creation, which has already found success in various medical applications, to the creation of biomimetic materials (materials that mimic processes found in nature).

Yiming Hu et al. Single crystals of mechanically entwined helical covalent polymers, Nature Chemistry (2021). DOI: 10.1038/s41557-021-00686-2

https://phys.org/news/2021-05-scientists-first-ever-synthetic-dna-l...

Comment by Dr. Krishna Kumari Challa on May 18, 2021 at 11:37am

Collective intelligence can be predicted and quantified, new study finds

In order to address issues ranging from climate change to developing complex technologies and curing diseases, science relies on collective intelligence, or the ability of a group to work together and solve a range of problems that vary in complexity.

To better understand how to measure and predict collective intelligence, researchers used meta-analytic methods to evaluate data collected in 22 studies, including 5,349 individuals in 1,356 groups, and found strong support for a general factor of collective intelligence (CI). Furthermore, the data demonstrated that group collaboration processes were about twice as important for predicting CI than individual skill, and that group composition, including the proportion of women in a group and group member social perceptiveness, are also significant predictors of CI.

The paper, "Quantifying Collective Intelligence in Human Groups," by Christoph Riedl (Northeastern University), Young Ji Kim (University of California, Santa Barbara), Pranav Gupta (Carnegie Mellon University), Thomas W. Malone (MIT Sloan School of Management), and Williams Woolley, Anita (Carnegie Mellon University) will be published in Proceedings of the National Academy of Sciences of the United States of America.

Christoph Riedl el al., "Quantifying collective intelligence in human groups," PNAS (2021). www.pnas.org/cgi/doi/10.1073/pnas.2005737118

https://phys.org/news/2021-05-intelligence-quantified.html?utm_sour...

Comment by Dr. Krishna Kumari Challa on May 18, 2021 at 9:24am

Mothers can influence offspring's height, lifespan and disease risk through mitochondria

Mitochondria—the 'batteries' that power our cells—play an unexpected role in common diseases such as type 2 diabetes and multiple sclerosis, concludes a study of over 350,000 people.

The study, published today in Nature Genetics, found that genetic variants in the DNA of mitochondria could increase the risk of developing these conditions, as well influencing characteristics such as height and lifespan.

There was also evidence that some changes in mitochondrial DNA were more common in people with Scottish, Welsh or Northumbrian genetic ancestry, implying that mitochondrial DNA and nuclear DNA (which accounts for 99.9% of our genetic make-up) interact with each other.

Almost all of the DNA that makes up the human genome—the body's 'blueprint' - is contained within the nuclei of our cells. Among other functions, nuclear DNA codes for the characteristics that make us individual as well as for the proteins that do most of the work in our bodies.

Our cells also contain mitochondria, often referred to as 'batteries', which provide the energy for our cells to function. They do this by converting the food that we eat into ATP, a molecule capable of releasing energy very quickly. Each of these mitochondria is coded for by a tiny amount of 'mitochondrial DNA'. Mitochondrial DNA makes up only 0.1% of the overall human genome and is passed down exclusively from mother to child.

While errors in mitochondrial DNA can lead to so-called mitochondrial diseases, which can be severely disabling, until now there had been little evidence that these variants can influence more common diseases. Several small-scale studies have hinted at this possibility, but scientists have been unable to replicate their findings.

Among those factors found to be influenced by mitochondrial DNA are: type 2 diabetes, multiple sclerosis, liver and kidney function, blood count parameters, life span and height. While some of the effects are seen more extremely in patients with rare inherited mitochondrial diseases—for example, patients with severe disease are often shorter than average—the effect in healthy individuals tends to be much subtler, likely accounting for just a few millimetres' height difference, for example.

There are several possible explanations for how mitochondrial DNA exerts its influence. One is that changes to mitochondrial DNA lead to subtle differences in our ability to produce energy. However, it is likely to be more complicated, affecting complex biological pathways inside our bodies—the signals that allow our cells to operate in a coordinated fashion.

Yonova-Doing, E et al. An atlas of mitochondrial DNA genotype-phenotype associations in the UK Biobank. Nature Genetics (2021). DOI: 10.1038/s41588-021-00868-1

https://phys.org/news/2021-05-mothers-offspring-height-lifespan-dis...

Comment by Dr. Krishna Kumari Challa on May 17, 2021 at 11:20am

Human Impact on Earth Is Shrinking an Entire Layer of The Atmosphere, Scientists Warn

Our world is hugged by complex layers of gases that make up the atmosphere. They protect and nurture all life as we know it. Now, we're shrinking an entire one of those layers – the stratosphere – thanks to the profound impacts we are having on our planet.

An alarming new study has found that the thickness of the stratosphere has already shrunk by 400 meters (1,312 feet) since 1980. While local decreases in the stratosphere's thickness have previously been reported, this is the first examination of this phenomenon on a global scale.

Greenhouse gas-induced warming in the troposphere is causing it to expand and squash the stratosphere above it, they explain. On top of this, the addition of CO₂ into the stratosphere itself is causing its combination of gasses to cool and huddle closer together (the opposite effect they have on the troposphere) – shrinking the entire layer.

In a plausible climate change scenario, our planet's stratosphere could lose 4 percent of its vertical extension (1.3 km [0.8 mi]) from 1980 to 2080.

https://iopscience.iop.org/article/10.1088/1748-9326/abfe2b

Comment by Dr. Krishna Kumari Challa on May 15, 2021 at 12:20pm

Scientists decode the 'language' of immune cells

scientists have identified six “words” that specific immune cells use to call up immune defense genes — an important step toward understanding the language the body uses to marshal responses to threats.

In addition, they discovered that the incorrect use of two of these words can activate the wrong genes, resulting in the autoimmune disease known as Sjögren’s syndrome. The research, conducted in mice, is published this week in the peer-reviewed journal Immunity (Cell Press).

Immune cells in the body constantly assess their environment and coordinate their defense functions by using words — or signaling codons, in scientific parlance — to tell the cell’s nucleus which genes to turn on in response to invaders like pathogenic bacteria and viruses. Each signaling codon consists of several successive actions of a DNA binding protein that, when combined, elicit the proper gene activation, in much the same way that successive electrical signals through a telephone wire combine to produce the words of a conversation.

The researchers focused on words used by macrophages, specialized immune cells that rid the body of potentially harmful particles, bacteria and dead cells. Using advanced microscopy techniques, they “listened” to macrophages in healthy mice and identified six specific codon–words that correlated to immune threats. They then did the same with macrophages from mice that contained a mutation akin to Sjögren’s syndrome in humans to determine whether this disease results from the defective use of these words.

Scientists found defects in the use of two of these words. The findings, the researchers say, suggest that Sjögren’s doesn’t result from chronic inflammation, as long thought, but from a codon–word confusion that leads to inappropriate gene activation, causing the body to attack itself. The next step will be to find ways of correcting the confused word choices.

Many diseases are related to miscommunication in cells, but this study, the scientists say, is the first to recognize that immune cells employ a language, to identify words in that language and to demonstrate what can happen when word choice goes awry.

How are immune cells so effective at mounting a response that is specific and appropriate to each pathogen? The answer, Hoffman says, lies in “signaling pathways,” the communication channels that link immune cells’ receptor molecules — which sense the presence of pathogens — with different kinds of defense genes. The transcription factor NFκB is one of these signaling pathways and is recognized as a central regulator of immune cell responses to pathogen threats.

T he macrophage is capable of responding to different types of pathogens and mounting different kinds of defenses. The defense units — army, navy, air force, special operations — are mediated by groups of genes,” he said. “For each immune threat, the right groups of genes must be mobilized. That requires precise and reliable communication with those units about the nature of the threat. NFκB dynamics provide the communication code. 

And of course, calling up the wrong unit is not only ineffective but may do damage, as vehicles destroy roads, accidents happen and worse, as in the case of Sjogren’s and, possibly, other diseases.

https://newsroom.ucla.edu/releases/ucla-scientists-decode-the-langu...

https://researchnews.cc/news/6686/UCLA-scientists-decode-the--langu...

Comment by Dr. Krishna Kumari Challa on May 15, 2021 at 11:29am

COVID-19 vaccine does not damage the placenta in pregnancy

 A new  study of placentas from patients who received the COVID-19 vaccine during pregnancy found no evidence of injury, adding to the growing literature that COVID-19 vaccines are safe in pregnancy. The placenta is like the black box in an airplane. If something goes wrong with a pregnancy, we usually see changes in the placenta that can help us figure out what happened.

The COVID vaccine does not damage the placenta. The study was published May 11 in the journal Obstetrics & Gynecolog.

The study authors collected placentas from 84 vaccinated patients and 116 unvaccinated patients who delivered at Prentice Women’s Hospital in Chicago and pathologically examined the placentas whole and microscopically following birth. Most patients received vaccines – either Moderna or Pfizer – during their third trimester.

Until infants can get vaccinated, the only way for them to get COVID antibodies is from their mother

--

The placenta is the first organ that forms during pregnancy. It performs duties for most of the fetus’ organs while they’re still forming, such as providing oxygen while the lungs develop and nutrition while the gut is forming.

Additionally, the placenta manages hormones and the immune system, and tells the mother’s body to welcome and nurture the fetus rather than reject it as a foreign intruder.

The scientists also looked for abnormal blood flow between the mother and fetus and problems with fetal blood flow – both of which have been reported in pregnant patients who have tested positive for COVID.

The rate of these injuries was the same in the vaccinated patients as for control patients.

 The scientists also examined the placentas for chronic histiocytic intervillositis, a complication that can happen if the placenta is infected, in this case, by SARS-CoV-2. Although this study did not find any cases in vaccinated patients, it's a very rare condition that requires a larger sample size (1,000 patients) to differentiate between vaccinated and unvaccinated patients.

Elisheva D. Shanes, Sebastian Otero, Leena B. Mithal, Chiedza A. Mupanomunda, Emily S. Miller, Jeffery A. Goldstein. Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Vaccination in Pregnancy. Obstetrics & Gynecology, 2021; Publish Ahead of Print DOI: 10.1097/AOG.0000000000004457

https://www.sciencedaily.com/releases/2021/05/210511201116.htm

https://researchnews.cc/news/6699/COVID-19-vaccine-does-not-damage-...

Comment by Dr. Krishna Kumari Challa on May 15, 2021 at 11:00am

meteorites - part 3:

This article is republished from The Conversation under a Creative Commons license. Read the original article.

https://phys.org/news/2021-05-meteorites-tracked-hundreds-fireballs...

Comment by Dr. Krishna Kumari Challa on May 15, 2021 at 10:59am

Meteorites - part 2

In total, scientists around the world have collected more than 60,000 meteorites, mostly from desert regions such as Antarctica or Australia's Nullarbor Plain.

We now know most of these come from the main asteroid belt—a region between Mars and Jupiter.

But might some of them have come not from asteroids, but from comets that originated in the outer reaches of the solar system? What would such meteorites be like, and how would we find them?

Fortunately, we can actively look for meteorites, rather than hoping to stumble across one lying on the ground. When a space rock is falling through the atmosphere (at this stage, it's known as a meteor), it begins to heat up and glow—hence why meteors are nicknamed "shooting stars."

Larger meteors (at least tens of centimeters across) glow brightly enough to be termed "fireballs." And by training cameras on the sky to spot them, we can track and recover any resulting meteorites.

The largest such network is the Desert Fireball Network, which features around 50 cameras covering more than 2.5 million square kilometers of the Australian outback.

The network's data has resulted in the recovery of six meteorites in Australia, and two more internationally. What's more, by tracking a fireball's flight through the atmosphere, we can not only project its path forwards to find where it landed, but also backwards to find out what orbit it was on before it got here.

Our research, published in the Planetary Science Journal, scoured every fireball tracked by the DFN between 2014 and 2020, in search of possible cometary meteorites. In total, there were 50 fireballs that came from comet-like orbits not associated with a meteor shower.

Unexpectedly, despite the fact that just under 4% of the larger debris was from comet-like orbits, none of the material featured the hallmark "dirty snowball" chemical composition of true cometary material.

We concluded that debris from comets breaks up and disintegrates before it even gets close to becoming a meteorite. In turn, this means cometary meteorites are not represented among the tens of thousands of objects in the world's meteorite collections.

The next question is: if all meteorites are asteroidal, how did some of them end up in such weird, comet-like orbits?

For this to be possible, debris from the main asteroid belt must have been knocked from its original orbit by a collision, close gravitational encounter, or some other mechanism.

Meteorites have given us our most profound insights into the formation and evolution of our solar system. However, it is now clear that these samples represent only part of the whole picture. It is definitely an argument for a sample-return mission to a comet. It's also testament to the knowledge we can gain from tracking fireballs and the meteorites they sometimes leave behind.

---

• ‹ Previous
• 1
• …
• 628
• 629
• 630
• 631
• 632
• …
• 1081
• Next ›
• Page