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Monday, 27 January 2020

Researchers develop "living concrete" capable of self-regeneration

Example of self-regenerating concrete. | Genie-inc.com


American researchers have developed a “living” building material, incorporating many photosynthetic bacteria. The material thus acts like a living organism: it is capable of developing and regenerating at an impressive speed.

“Living concrete”, as it is now called in the press, consists essentially of a mixture of gelatin, sand and cyanobacteria. Developed and tested by scientists at the University of Colorado at Boulder (United States), the resulting structure was able to regenerate three times after being cut, suggesting a potential breakthrough in the emerging field of self-healing materials.

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The innovative material, developed in partnership with DARPA (Defense Advanced Research Projects Agency), presents a khaki green color after manufacturing. The initial coloring then fades as the bacteria die.

"It really looks like Frankenstein-like material ," Will Srubar told the New York Times , engineer and project manager at UC Boulder.

An arch molded with living and self-regenerating building material, in the laboratory of Dr. Srubar. Credits: CU Boulder College of Engineering & Applied Science

Even when the color fades, the bacteria survive for several weeks and can be rejuvenated - causing further growth - under the right conditions. The results of the study were published Wednesday in the journal Matter .

"The new material represents an exciting new class of low carbon designer building materials ," said Andrea Hamilton, construction expert at the University of Strathclyde, Scotland.

To develop it, the researchers first tried to introduce cyanobacteria into a mixture of hot water, sand and nutrients. The microbes then absorbed the light and began to produce calcium carbonate, gradually cementing the sand particles together. But the process was slow, and DARPA (the research arm of the Ministry of Defense and the project funder) wanted construction to take place very quickly. This need then accelerated the birth of this new, more efficient version of the material.


Gelatin added to the “mixture”

Dr. Srubar has worked with gelatin in the past, a food ingredient that, when dissolved in water and cooled, forms special bonds between its molecules. It is important to note that gelatin can be used at moderate temperatures which are mild to bacteria. Srubar therefore suggested adding gelatin to strengthen the matrix built by cyanobacteria, intriguing his team, which was impatient to try.

The researchers then bought gelatin (Knox brand) from a local supermarket and dissolved it in the solution containing the bacteria. When they poured the mixture into molds and cooled it, the gelatin formed its bonds. In other words, gelatin had just strengthened the structure and helped the bacteria to do their job, making the material more resistant and accelerating its self-regeneration / development.

The structure of living building material (LBM) is supported by the physically crosslinked hydrogel as well as by precipitation of bacterial calcite. In the event of a drop in humidity, the mechanical properties of the structure are improved. Conversely, the higher the humidity, the more the self-regenerating capacities of the material increase. Credits: University of Colorado (Boulder)

After about a day, the mixture made it possible to form concrete blocks with any mold used by the group, including 5 cm cubes, blocks the size of a shoe box and pieces of trellis. with spacers and cutouts.

The individual 5 cm cubes were strong enough for a person to stand on, although the material was brittle compared to most conventional concrete. The blocks the size of a shoebox, however, have shown that it is possible to make real constructions.


Potential use in space

DARPA is particularly interested in a self-cultivation material that could be used to assemble structures in remote desert areas, even potentially in space. Living concrete could also be useful in harsher environments than the driest land deserts, such as on Mars for example.

If live concrete can reach this level of use, it could reduce the quantity - and the weight - of materials that space agencies will have to send into orbit. " There is no way to transport building materials into space, " said Srubar. " So we will bring biology with us ."


Bibliography:

Biomineralization and Successive Regeneration of Engineered Living Building Materials
Chelsea M. Heveran, Sarah L. Williams, Jishen Qiu, Juliana Artier, Mija H. Hubler, Sherri M. Cook, Jeffrey C. Cameron, Wil V. Srubar III

Published:January 15, 2020

DOI:https://doi.org/10.1016/j.matt.2019.11.016

Gravity on a quantum scale would have no symmetry


In physics, symmetry means the conservation of physical laws, or of certain quantities, under transformations or operations. For many years, theorists have been convinced that the fundamental laws describing our Universe, from stars to particles, are necessarily based on symmetries. However, gravity could escape this rule. Indeed, two physicists have shown that on the quantum scale, gravity has no symmetry. If this conception proves to be correct, the current theoretical models which are limited to describing quantum gravity should be modified.

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There are four basic interactions: electromagnetism, strong and weak nuclear interactions, and gravity. Gravity is the only force that does not yet have a description at the quantum level. Its effects on large objects, such as planets or stars, are relatively easy to describe, but things get complicated when the effects of gravity manifest on a quantum scale.


The holographic principle to describe gravity on a quantum scale

To try to understand gravity at the quantum level, Hirosi Ooguri, director of the Kavli Institute for Physics and Mathematics of the Universe in Tokyo, and Daniel Harlow, assistant professor at the Massachusetts Institute of Technology (MIT), started with the holographic principle. This principle explains the three-dimensional phenomena influenced by gravity on a flat two-dimensional space not influenced by gravity.

The researchers have shown that symmetry only affects the hatched areas of the diagram, not the surroundings of the point in the middle, so there can be no overall symmetry. Credits: KAVLI

It is not a real representation of our universe, but it is close enough to help researchers study its fundamental aspects. Earlier work by Harlow and others had found a precise mathematical analogy between the holographic principle and quantum error correction codes, which protect information in a quantum computer.

Ooguri and Harlow have shown that these quantum error correction codes are not compatible with any symmetry, which means that symmetry would not be possible in quantum gravity.

Better understand quantum gravity and its potential lack of symmetry

This work began over four years ago, when Ooguri discovered an article on holography and its relationship to quantum error correction codes by Harlow, who was then a post-doctoral fellow at Harvard University. Shortly after, the two met at the Institute for Advanced Study in Princeton, when Ooguri was on sabbatical and Harlow came to give a seminar.

“ I went to his seminar, prepared with questions. We talked a lot afterwards, then we started to think that the idea he had developed could perhaps be used to explain one of the fundamental properties of quantum gravity, about the lack of symmetry "explains Ooguri.

Their result has several important consequences. In particular, he predicts that protons are stable and do not disintegrate into other elementary particles, and that there are magnetic monopoles.



Although the two theorists have provided theoretical proof of the absence of symmetry in the context of quantum gravity, this preliminary work still needs to be deepened. If these works were generally well received by their peers, the researchers recall that the theoretical framework they used must be developed further.


Bibliography:

Constraints on Symmetries from Holography

Daniel Harlow and Hirosi Ooguri

Phys. Rev. Lett. 122, 191601

DOI:https://doi.org/10.1103/PhysRevLett.122.191601

Scientists create Crystal inside a crystal to improve screens and more

The beautiful patterns created by blue liquid phase crystals have a number of technological applications.

Liquid crystals have enabled new technologies, such as LCD screens, thanks to their ability to reflect certain wavelengths of light, or colors, and to be very easy to manipulate.

Researchers have now developed an innovative way to sculpt a crystal inside a liquid crystal.
Because these crystals within crystals can reflect light at certain wavelengths that others cannot, they can be used to improve screen and monitor technologies.

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They can also be manipulated with temperature, electrical voltage or chemicals, which makes them valuable for detection applications. Temperature changes, for example, would result in color changes. And since these changes require only small temperature variations or small voltages, the devices would consume very little energy.

Creating an interface between crystals

The molecular orientation of liquid crystals makes them useful in key functions of various display technologies. They can also form "blue phase crystals", in which the molecules are arranged in highly regular patterns, which reflect visible light.

To design a blue phase crystal interface, Xiao Li and his colleagues at the University of Chicago, USA, developed a method that is based on chemically patterned surfaces, on which liquid crystals are deposited, thus providing a means of manipulating their orientation molecular. This orientation is then amplified by the liquid crystal itself, allowing a specific blue phase crystal to be carved into another blue phase crystal.



The process, the result of theoretical predictions and experimentation to arrive at the right design, allowed the creation of specific crystal forms within the liquid crystals - something unprecedented.

Not only that: The newly sculpted crystal can be manipulated with temperature and electricity to change from a blue phase to another type of blue phase, thus changing color.

"This means that the material can change its optical characteristics very precisely," said Professor Juan de Pablo, from the Argonne National Laboratory. "We now have material that can respond to external stimuli and reflect light at specific wavelengths, for which we had no good alternatives before."

This ability to manipulate crystals on such a small scale also makes it possible to use them as models to manufacture perfectly uniform structures at the nanoscale.

Details of the manufacturing process and the interfaces inside the crystal.

Blue phase crystals

Blue phase crystals have the properties of liquids and crystals, which means that they can flow and are flexible, while having highly regular characteristics that transmit or reflect visible light.

They also have better optical properties and a faster response time than traditional liquid crystals, making them good candidates for optical technologies.

In addition, the projections responsible for reflecting light in the blue phase crystals are separated by relatively large distances compared to traditional crystals, such as quartz. The larger size of these projections facilitates the engineering of the interfaces between them, a process notoriously difficult in traditional crystalline materials.

These interfaces are important because they provide ideal locations for chemical reactions and mechanical transformations, and because they can make it difficult to transport sound, energy or light.





Bibliography:

Article: Sculpted grain boundaries in soft crystals

Authors: Xiao Li, José A. Martínez-González, Orlando Guzmán, Xuedan Ma, Kangho Park, Chun Zhou, Yu Kambe, Hyeong Min Jin, James A. Dolan, Paul F. Nealey , Juan J. de Pablo

Magazine: Science Advances

Vol .: 5, no. 11, eaax9112

DOI: 10.1126 / sciadv.aax9112

English nuclear fusion reactor restarted for the first time in 23 years


Mastering nuclear fusion promises clean, unlimited energy. Many countries have already embarked on the fusion race with extremely promising results. Now it is England's turn to restart a prototype fusion reactor that has not been used for 23 years. The researchers hope to create a plasma stable enough to help ITER in its future trials.

In less than a year, researchers will try to create a plasma hotter than the Sun inside a torus-shaped machine in the south-east of England. It will be the country's first nuclear fusion operation in the last century.



The attempt to merge two hydrogen isotopes in November at the Joint European Torus (JET) in Culham, Oxfordshire, will be the first since the facility broke the record for electricity production by nuclear fusion for less than d 'a second in 1997.

Commercial nuclear fusion holds the promise of clean, unlimited energy, but is far from being realized. So far, test projects have consumed more energy (creating the reaction) than they produce. The UK is keen to be a leader in this area, with the government having committed £ 200 million last year for a project to build a commercial power plant based on fusion.

A structurally modified reactor for a more stable plasma

JET will import fuel from Canada for the November return to service: a few grams of each of the hydrogen, deuterium and tritium isotopes over the next few months. Once fused, they will produce a plasma with a temperature of 100 million degrees Celsius, which will be held in place by magnets.

The interior of the reactor has been completely modified to resemble the internal structure of ITER. Credits: JET

There are two key differences between this year's reaction and that of 23 years ago. The most important is that the materials used inside the reactor have been modified, with carbon-based materials such as graphite, replaced by tungsten and beryllium. Carbon acts like a sponge for hydrogen, so the change should mean more hydrogen in the plasma, rather than ending up in the wall.

The second difference is the lifetime of the plasma. In 1997, the maximum output of 16 megawatts lasted only a few milliseconds before the disappearance of the plasma. The group hopes that this time the plasma can be maintained for at least 5 seconds. Whatever the outcome, Wilson says the resulting data will be vital to assist ITER in manufacturing its first plasma, which is currently slated for 2025.


A new type of evolutionary process has been highlighted


Evolution and natural selection takes place at the DNA level, because genes mutate and genetic traits persist or get lost over time. But now biologists believe that evolution can take place on a whole new scale - transmitted not by genes, but by molecules linked to their surface and responsible for their methylation. This mechanism would allow the conservation of an epigenome by enzymatic processes through several tens of millions of years, according to a process analogous to that of the Darwinian evolution of the genome.

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These molecules, known as "methyl groups", modify the structure of DNA and can turn genes on and off. The alterations are known as "epigenetic changes". Many organisms, including humans, have DNA dotted with methyl groups, but creatures like Drosophila and roundworms have lost the genes necessary to do so during the evolutionary period.

Another organism, the yeast Cryptococcus neoformans , also lost key genes for methylation during the Cretaceous, about 50 to 150 million years ago. But remarkably, in its current form, the fungus still has methyl groups in its genome. Now, scientists theorize that C. neoformans was able to conserve epigenetic changes for tens of millions of years, thanks to a new mode of evolution. The study was published in the journal Cell.


Methyl groups present in C. neoformans

The authors generally study C. neoformans to better understand how yeast causes fungal meningitis in humans. The fungus tends to infect people with weak immune systems and causes about 20% of all AIDS-related deaths.

Hiten Madhani, professor of biochemistry and biophysics at the University of California, and his colleagues, spend part of their days researching the genetic code of C. neoformans , looking for critical genes that help yeast invade human cells.

But the team was surprised when reports emerged, suggesting that the genetic material was adorned with methyl groups. In vertebrates and plants, cells add methyl groups to DNA using two enzymes. The first, de novo methyltransferase, links methyl groups to unadorned genes.

Diagram explaining the functioning of methylation via the intervention of de novo methyltransferase and maintenance methyltransferase. Credits: Nature


The enzyme adds to each half of the helical DNA strand the same methyl group pattern, creating a symmetrical design. During cell division, the double helix unwinds and builds two new strands of DNA from the corresponding halves. At this stage, an enzyme called "maintenance methyltransferase" intervenes to copy all the methyl groups from the original strand to the newly constructed half.

De novo methyltransferase loss and maintenance of methyltransferase compensation

Madhani and his colleagues examined existing evolutionary trees to trace the history of C. neoformans over time and found that, during the Cretaceous period, the ancestor of the yeast had the two enzymes necessary for the methylation of l DNA. But somewhere along the line, C. neoformans lost the gene needed to make de novo methyltransferases

During its evolutionary process, C. neoformans lost de novo methyltransferase and retained the maintenance methyltransferase. Credits: Sandra Catania et al. 2020

Without the enzyme, the body could no longer add new methyl groups to its DNA - it could only copy existing methyl groups by using its maintenance enzyme. In theory, even when working alone, the maintenance enzyme could keep DNA covered with methyl groups indefinitely - if it could make a perfect copy every time.

Natural selection at the origin of the conservation of a methylation mechanism

In reality, the team discovered that the enzyme makes mistakes and loses track of methyl groups every time the cell divides. When grown in a petri dish, C. neoformans cells occasionally gain new methyl groups in the same way that random mutations occur in DNA. However, cells lost methyl groups about 20 times faster than they could gain new ones.

In about 7,500 generations, each last methyl group would disappear, leaving nothing to be copied by the maintenance enzyme, the team estimated. Given the speed at which C. neoformans multiplies, the yeast should have lost all of its methyl groups in about 130 years. Instead, it retained the epigenetic changes for tens of millions of years.

Despite the loss of DNMT, C. neoformans can still use methylation thanks to compensation by its maintenance methyltransferase. A process preserved by natural selection. Credits: Sandra Catania et al. 2020

“ Because the rate of loss is higher than the rate of gain, the system would slowly lose methylation over time if there were no mechanism to maintain it. This mechanism is natural selection, ”explains Madhani. In other words, even if C. neoformans gained new methyl groups much more slowly than it lost them, methylation considerably increased the endurance of the organism, which meant that it could surpass individuals with less methylation.

Use methylation to control transposons

Enduring individuals have prevailed over those with fewer methyl groups, and thus, methylation levels have remained higher over millions of years. But what evolutionary advantage could these methyl groups offer to C. neoformans ? Well, they could protect the yeast genome from life-threatening damage.

Transposons, also known as "jumping genes", jump into the genome at will and often fit into very impractical places. For example, a transposon could jump to the center of a gene necessary for cell survival; this cell could malfunction or die. Fortunately, the methyl groups can cling to the transposons and lock them in place. It may be that C. neoformans maintain a certain level of DNA methylation to control transposons.


Understanding methylation in C. neoformans

Many mysteries still surround DNA methylation in C. neoformans . Besides copying methyl groups between strands of DNA, maintenance methyltransferase appears to be important in terms of how yeast causes infection in humans, according to a 2008 study by Madhani. Without the intact enzyme, the body cannot attack cells as effectively.

The enzyme also requires large amounts of chemical energy to function and copies only the methyl groups on the pristine half of the replicated DNA strands. In comparison, the equivalent enzyme in other organisms does not require additional energy to function and sometimes interacts with naked DNA, devoid of any methyl group. Further research will reveal exactly how methylation works in C. neoformans and whether this new form of evolution occurs in other organisms.


Bibliography:

Evolutionary Persistence of DNA Methylation for Millions of Years after Ancient Loss of a De Novo Methyltransferase

Sandra Catania, Phillip A. Dumesic, Harold Pimentel,  Ammar Nasif
Caitlin I. Stoddard
Jordan E. Burke
Jolene K. Diedrich
Sophie Cook
Terrance Shea
Elizabeth Geinger
Robert Lintner
John R. Yates III
Petra Hajkova
Geeta J. Narlikar
Christina A. Cuomo
Jonathan K. Pritchard
Hiten D. Madhani

Published:January 16, 2020

DOI:https://doi.org/10.1016/j.cell.2019.12.012

Sunday, 26 January 2020

Four new species of walking sharks discovered in Australia



The vast majority of sharks swim to move around, but some specific species can use more unique means of transport. This is the case of walking sharks, that is to say sharks using their fins as limbs to move on the seabed. And recently, four new species of walking sharks have been discovered by Australian marine biologists.

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Unlike their larger cousins, members of these newly discovered species of walking sharks spend their time wandering gently along coral reefs on four flat fins. Or, at least, that's what they were doing when the researchers spotted them in the shallow waters of northern Australia.

In an article published in the journal Marine & Freshwater Research , marine biologists declared that the four new itinerant shark species were the most recently evolved shark species known, having developed after having separated from their common ancestor on closer about 9 million years ago.


Walking sharks: unique characteristics for a definite evolutionary advantage

" With an average length of less than one meter, walking sharks pose no threat to humans, but their ability to withstand oxygen-poor environments and to walk on their fins gives them a remarkable advantage over their prey, small crustaceans and molluscs ”explain the researchers.

Walking sharks have unique characteristics compared to their closest relatives. Credit: Mark Erdmann

These unique characteristics are not shared with their closest relatives, whip sharks, or more distant relatives in order of carpet sharks, including whale sharks. The four new species almost doubled the total number of known walking sharks, bringing the total to nine. the researchers said they live in the coastal waters of northern Australia and the island of New Guinea and occupy their own separate region.

Better understand the evolution of walking sharks

“ We estimated the link between the species on the basis of comparisons between their mitochondrial DNA which is transmitted through the maternal line. This DNA codes for mitochondria, which are the parts of cells that convert oxygen and nutrients from food into energy for cells . ”

The data suggest that the new species evolved after sharks moved away from their original population, became genetically isolated in new areas, and developed into new species.



This video shows a walking shark moving on the ocean floor:




Bibliography:

Walking, swimming or hitching a ride? Phylogenetics and biogeography of the walking shark genus Hemiscyllium

Christine L. Dudgeon A H , Shannon Corrigan B , Lei Yang B , Gerry R. Allen C , Mark V. Erdmann D E , Fahmi A F , Hagi Y. Sugeha F , William T. White G and Gavin J. P. Naylor B

Marine and Freshwater Research

https://doi.org/10.1071/MF19163

World's fastest rotating object to study vacuum friction

The fastest-spinning object ever created is a nano-scale rotor made from silica at Purdue University. This image of the rotor at rest was created using a scanning electron microscope. For scale, the yellow bar in the image is 200 nanometers. (Purdue University photo/Jaehoon Bang)


In 2018, a team from the U.S. and another from Switzerland, working independently, created the world's fastest rotating objects , which are helping to study the true nature of the quantum vacuum .

These studies now promise to be even more accurate, as Jonghoon Ahn and his colleagues at Purdue University in the U.S. upgraded their nanorotor, which now spins an impressive 300 billion RPM (revolutions per minute), which is a bit million times faster than a dentist's drill.

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The rotor, measuring 200 nanometers (0.2 micrometer), consists of two silica particles joined by the center, which gives it a shape that resembles a dumbbell.

It does not need an axis because the nanoparticle is levitated in a vacuum by optical tweezers. Then, another laser is used to make the particle spin, transmitting torque by the pressure of light radiation , the same principle that drives solar sails in space.

Polarized light induced by the laser transmits a torque that makes the nanorotor spin.

As it receives torque from the light, whose power can be carefully controlled, the rotor itself becomes an extremely sensitive torque detector - in fact, the most sensitive one ever manufactured, being 600 to 700 times better than its predecessors.

This will allow it to continue to be used to explore the mysteries of the vacuum. Contrary to what you can imagine, the vacuum is far from being something empty, being full of virtual particles that emerge and decay all the time. With its sensitivity, this new version of the fastest object in the world will allow to detect and measure the torque of these emerging particles.

In other words, it will be used to measure vacuum-induced friction.

The torque nanodetector can also be used to measure related effects, including the Casimir effect and nanoscale magnetism, phenomena essential for the development of nanoscale devices, such as NEMS , nanomachines and nanorobots.




Bibliography:

Article: Ultrasensitive torque detection with an optically levitated nanorotor

Authors: Jonghoon Ahn, Zhujing Xu, Jaehoon Bang, Peng Ju, Xingyu Gao, Tongcang Li

Magazine: Nature Nanotechnology

DOI: 10.1038 / s41565-019-0605-9

Saturday, 25 January 2020

Researchers find way to harness the entire visible spectrum for energy production



For the very first time, scientists have demonstrated that it is possible to collect energy from the entire visible spectrum of sunlight and transform it quickly and efficiently into hydrogen. In fact, they have developed a single molecule that can efficiently absorb sunlight and also act as a catalyst to transform solar energy into hydrogen. A clean alternative to fossil fuels (for, in particular, motor vehicles).

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This new molecule collects energy from the entire visible spectrum and can harness more than 50% more solar energy than current solar cells. This discovery could well help humanity move from fossil fuels to energy sources that do not contribute to climate change.

“  The idea is to use the photons from the sun and transform them into hydrogen. Simply put, we collect energy from sunlight and store it in chemical bonds so it can be used later, "said Claudia Turro, professor of chemistry and director of the center at Ohio State University for chemical and biophysical dynamics (and who also directed this research). Namely, that photons are the elementary particles of light, and contain a certain amount of energy.



Thanks to this study, for the very first time, it has been demonstrated that it is possible to collect energy from the entire visible spectrum of sunlight, including low energy infrared ( part of the solar spectrum that had previously been difficult to collect) and transform it quickly and efficiently into hydrogen.

Hydrogen is a clean fuel, which means that it does not produce carbon or carbon dioxide as a by-product of its use. "  What makes it work is that the system is able to put the molecule in an excited state, where it absorbs the photon and is able to store two electrons to produce hydrogen. This storage of two electrons in a single molecule, as well as this use to produce hydrogen, is unprecedented,  ”said Turro.

Indeed, transforming the Sun's energy into fuel, for example to power a vehicle, first requires an energy collection mechanism. Then, this energy can be converted into fuel. The conversion requires a catalyst. In short: this is a device which accelerates a chemical reaction allowing the conversion of solar energy into a usable energy vector (in this case hydrogen).

Most of the previous attempts to collect solar energy and transform it into hydrogen have focused on higher energy wavelengths (like ultraviolet, for example). The latter have also relied on catalysts always involving two molecules (or more), which exchange electrons (energy) to produce fuel from solar energy. But a large part of this energy is lost in the exchange, which makes these multimolecular systems less efficient.

In addition, the few other attempts that relied on a single molecule catalyst were also ineffective "partly because they did not collect energy from the entire visible spectrum of the sun, and also because the catalysts themselves degraded quickly, "said Turro.


A system 25 times more efficient than current technologies

Now, Turro's research team has discovered how to make a catalyst from a single molecule, a form of rhodium (a chemical element), which means less energy is lost. The researchers also understood how to collect energy from the near infrared to the ultraviolet, more than the entire visible spectrum.

According to the researchers, the system they designed is nearly 25 times more efficient with low-energy near-infrared light than single-molecule systems operating with ultraviolet photons.

As part of this study, the researchers used LEDs to illuminate acid solutions containing the active molecule, and discovered that hydrogen was produced.

" I think the reason it works is because the molecule is difficult to oxidize,  " says Turro. "  And we have to have renewable energy. Just imagine, if we could use sunlight for our energy needs instead of coal, gas or oil, what we could do to fight climate change, ”added Turro.

But before the research team's results can be applied in the real world, "there is still a lot of work to do," admits Turro. Indeed, rhodium is a rare metal and the production of catalysts using it is expensive. The team is therefore working to improve this molecule to produce hydrogen over a longer period of time and to develop a catalyst exploiting less rare elements.




Bibliography:

Article: Single-chromophore single-molecule photocatalyst for the production of dihydrogen using low-energy light

T. J. Whittemore, C. Xue, J. Huang, J. C. Gallucci & C. Turro

Nature Chemistry (2020)

https://doi.org/10.1038/s41557-019-0397-4

Researchers have developed a camera that captures the “invisible” at a billion frames per second

A new ultra-fast image capture device has been developed by scientists at Caltech. | Caltech

Scientists continue to push the limits of current optical devices, especially when it comes to studying physical or chemical phenomena. Recently, a team of Caltech researchers created a new ultra-fast image capture device (pCUP, from the English phase-sensitive compressed ultrafast photography), capable of taking a billion images per second.

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While this is an absolutely mind-boggling number, this new creation does not set a record. Indeed, some researchers (from the same team) had already developed, in 2018, a camera with a capture frequency of 10 trillion images per second (10,000,000). However, this new device has more than one string to its bow: it can capture transparent objects, as well as other phenomena invisible to the naked eye, such as shock waves for example.

While this incredible technology isn't very useful for vacation videos or Instagram selfies, it promises to have a variety of scientific uses across physics, biology, and chemistry.



The device works using the innovative technique used in the 2018 model, where light intensity measurements are combined with a static image as well as advanced algorithms.

But the device still has a new element, it uses phase contrast microscopy : it is an older photographic technique where changes in the relative positions of light waves, as they pass through different densities , are converted into variations in brightness. This allows transparent objects, such as cells made mainly of water, to be imaged.

" What we have done is to adapt standard phase contrast microscopy so that it provides very fast imaging, which allows us to image ultrafast phenomena in transparent materials ", explains Lihong Wang, electrical engineer at California Institute of Technology (Caltech).

A shock wave created by a laser striking slow-moving water has been captured by new ultra-fast photography technology, capturing a billion frames per second. Credit: Caltech

Namely, that phase contrast microscopy was invented by the Dutch physicist Frits Zernike in the 1930s, and exploits the phase changes of a light wave passing through a material. Thus, these speed changes make materials like glass much easier to spot with this technique.

As for the latest feature of this new device, the Caltech team calls it lossless encoding compressed ultra-fast technology ( LLE-CUP , from English lossless encoding compressed ultrafast technology). This marks the next generation of cameras and scanners, which capture an entire event at one time, recording the timing of light waves.

A pulse of laser light travels through a crystal (seen in slow motion), also captured by new ultra-fast photography technology. Credit: Caltech


Wang's previous work added a new component: a charge coupled device. Now, Wang has combined an improved form of this configuration with microscopy that filters out scattered light to map changes that the human eye cannot see. This type of scientific device, more and more sophisticated, will undoubtedly lead to new discoveries on the world which surrounds us, whether it is by taking snapshots of the human body or by recording quantum entanglement.

In this case, the scientists managed to capture the movement of a shock wave in water, as well as a laser pulse through a crystalline material. In addition, "this device could be used for many other purposes in the future, because it can be combined with several other existing optical imaging systems," said the researchers.

It could for example allow scientists to observe in detail the expansion of the flames in the combustion chambers, or even to record the signals that pass through neurons on a microscopic scale. " When the signals travel through the neurons, there is a tiny dilation of the nerve fibers, which we hope to see. Maybe we could see the communication of a neural network in real time , ”said Wang.




Bibliography:

RESEARCH ARTICLE |APPLIED SCIENCES AND ENGINEERING
Picosecond-resolution phase-sensitive imaging of transparent objects in a single shot
Taewoo Kim1, Jinyang Liang1, Liren Zhu1 and Lihong V. Wang

Science Advances  17 Jan 2020:
Vol. 6, no. 3, eaay6200
DOI: 10.1126/sciadv.aay6200

Friday, 24 January 2020

Snakes are believed to be the cause of reported coronavirus disease in China



Since late December, a new coronavirus respiratory disease has emerged in China. It has already caused several hundred victims. Now, the new strain of coronavirus baptized 2019-nCoV by the WHO, has spread to several other countries. To better understand the virus, virologists must trace its origin and the animal host through which it first passed before infecting humans. A recent study shows that 2019-nCoV was transmitted to humans in the Wuhan market from snakes.

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Snakes - Chinese krait and Chinese cobra - may be the initial source of the newly discovered coronavirus that triggered the onset of a deadly infectious respiratory disease in China this winter. The disease was first reported in late December 2019 in Wuhan, a large city in central China, and quickly spread. Since then, sick travelers from Wuhan have infected people in China and other countries, including the United States.

Using samples from the virus isolated from patients, Chinese scientists determined the genetic code of the virus and observed it. The pathogen responsible for this pandemic is a new coronavirus. It belongs to the same family of viruses as the well-known severe acute respiratory syndrome coronavirus SARS-CoV, and the Middle East respiratory syndrome coronavirus (MERS-CoV), which have killed hundreds of people in the past 17 years. The World Health Organization (WHO) has named the new coronavirus “2019-nCoV”.


What is coronavirus?

The name of the coronavirus comes from its shape, which resembles a crown or a solar crown when imaged using an electron microscope. The coronavirus is transmitted by air and mainly infects the upper respiratory and gastrointestinal tracts of mammals and birds.

Although most members of the coronavirus family cause only mild flu-like symptoms during infection, SARS-CoV and MERS-CoV can infect the upper and lower respiratory tract, causing severe respiratory illness and other complications in humans.

The 2019-nCoV coronavirus observed under the electron microscope. Credits: CDC Chine

2019-nCoV causes symptoms similar to those of SARS-CoV and MERS-CoV. People infected with these coronaviruses suffer from a severe inflammatory reaction. Unfortunately, no approved antiviral vaccine or treatment is available for coronavirus infection. A better understanding of the 2019-nCoV life cycle, including the source of the virus, how it is transmitted and how it replicates is necessary to prevent and treat the disease.

2019-nCoV: an initial transmission from animals to humans

SARS and MERS are classified as zoonotic viral diseases, which means that the first infected patients acquired these viruses directly from animals. This was possible because, in the host animal, the virus had acquired a series of genetic mutations which allowed it to infect and multiply inside humans.

These viruses can now be transmitted between humans. Field studies have revealed that the original source of SARS-CoV and MERS-CoV is the bat and that masked palm civets (a mammal native to Asia and Africa) and camels , respectively, are used intermediate hosts between bats and humans.

This graph shows the origins of the different coronaviruses. The initial strains all come from bats. Credits: Science

In the case of this coronavirus epidemic in 2019, reports indicate that most of the patients in the first hospital group were workers or customers of a local wholesale seafood market which also sold processed meats and consumable animals living.

Including poultry, donkeys, sheep, pigs, camels, foxes, badgers, bamboo rats, hedgehogs and reptiles. However, as no one has ever reported finding a coronavirus infecting aquatic animals, it is plausible that the coronavirus may have originated from other animals sold in this market.

A disease transmitted by bats?

The hypothesis that nCoV 2019 comes from an animal on the market is strongly supported by a new publication in the journal Journal of Medical Virology . Virologists have analyzed and compared the genetic sequences of 2019-nCoV and all other known coronaviruses.

Study of the 2019-nCoV genetic code reveals that the new virus is most closely linked to two samples of bat SARS-type coronavirus from China, initially suggesting that, like SARS and MERS, the bald -mouse could also be behind 2019-nCoV.

The authors further found that the DNA coding sequence for the 2019-nCoV peak protein, which forms the crown of the viral particle that recognizes the receptor on a host cell, indicates that the bat virus may have mutated before infecting people. But when the researchers performed a more detailed bioinformatic analysis of the 2019-nCoV sequence, it suggested that this coronavirus could have come from snakes.

2019-nCoV: it would have gone from the bat to the snake

The researchers used an analysis of the protein codes favored by the new coronavirus and compared it to the protein codes of the coronaviruses found in different animal hosts, such as birds, snakes, marmots, hedgehogs, manis, bats and humans. Surprisingly, they found that the 2019-nCoV protein codes are most similar to those used in snakes.



Snakes often hunt bats in the wild. Reports indicate that the snakes were sold in the local seafood market in Wuhan, raising the possibility that 2019-nCoV has passed from the host species - bats - to snakes, and then to humans at the start of this. coronavirus epidemic. However, how the virus could adapt to both cold-blooded and warm-blooded hosts remains a mystery.

The authors of the report and other researchers must verify the origin of the virus by laboratory experiments. The first thing to do is to find the 2019-nCoV sequence in snakes. However, since the epidemic, the seafood market has been disinfected and closed, making it difficult to trace the source animal of the new virus.

DNA sampling from market animals and wild snakes and bats is necessary to confirm the origin of the virus. However, the results reported will also provide information on the development of prevention and treatment protocols.


Bibliography:

RESEARCH ARTICLE:  Homologous recombination within the spike glycoprotein of the newly identified coronavirus may boost cross‐species transmission from snake to human

Wei Ji  Wei Wang  Xiaofang Zhao  Junjie Zai  Xingguang Li

First published: 22 January 2020

https://doi.org/10.1002/jmv.25682

Unknown ancient viruses discovered in a Tibetan glacier


A set of unknown viruses has been discovered in a glacier in the northwest of the Tibetan plateau in China. Researchers recently dissolved samples after examining two ice cores from the site, revealing the existence of 28 groups of viruses never seen before.

Studying these mysterious viruses could provide researchers with crucial information to determine which viruses have thrived in different climates and environments over time.

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" However, in the worst case scenario, this melting ice [due to climate change] could release pathogens into the environment, " wrote the researchers in the study, which has not yet been peer reviewed. . If this happens, it's best to know as much as you can about these viruses, the researchers wrote. The results of the research have been available for consultation on the bioRxiv server since January 7.

Studying ancient glacial organisms can be difficult. Indeed, it is extremely easy to contaminate samples of ice cores with current bacteria. Thus, the researchers created a new microbial and viral sampling protocol.


A new sampling protocol to avoid contamination

In this case, the two samples of ice cores, from the Guliya ice cap on the Tibetan plateau, were collected in 1992 and 2015. However, at that time, no specific measures were taken to avoid microbial contamination during drilling, handling or transporting carrots.

In other words, the outside of these ice cores was contaminated. But the interior was still pristine, the researchers wrote in the study. To access the inner part of the carrots without contaminating it, the researchers installed themselves in a cold room (at -5 degrees Celsius) and used a sterilized band saw to cut 0.5 cm of the ice from the outer layer. They then washed the ice cores with ethanol to melt another 0.5 cm of ice. Finally, they washed the next 0.5 cm with sterile water.

After this work (removal of 1.5 cm of ice), the researchers reached an uncontaminated layer which they were able to study. This method has proven to be effective even during tests in which they had coated the outer layer of the ice with other bacteria and viruses.

The experiment revealed 33 groups of viruses (or genera) in ice cores. Of these, 28 were previously unknown to science, the researchers said. " The microbes differed considerably across the two ice cores, presumably representing very different climatic conditions at the time of deposition, " the document said. It is not surprising that the glacier has kept these mysterious viruses for so long, they add.

" We are very far from sampling all the diversity of viruses on Earth, " says Chantal Abergel to Vice , researcher in environmental virology at the National Center for Scientific Research, who did not participate in the study.



Since human-induced climate change is melting glaciers around the world, these viral archives could be lost, the researchers noted. The study of ancient viruses “offers a first window on viral genomes and their ecology linked to glaciers. It also highlights their likely impact on today's abundant microbial groups, ”the researchers wrote.


Bibliography:

Glacier ice archives fifteen-thousand-year-old viruses

Zhi-Ping Zhong, Natalie E. Solonenko, Yueh-Fen Li, Maria C. Gazitúa, Simon Roux, Mary E. Davis, James L. Van Etten, Ellen Mosley-Thompson, Virginia I. Rich, Matthew B. Sullivan, Lonnie G. Thompson

doi: https://doi.org/10.1101/2020.01.03.894675

New UV-C laser diode promises to disinfect your various health conditions

Structure and prototype of the UV-C laser diode. [Image: Asahi Kasei Corp / Nagoya University]


Japanese researchers made a laser diode that emits the shortest wavelength ultraviolet light ever achieved, covering an area of ​​applications that until now has not benefited from lasers.

These new devices could be used for health disinfection, treatment of skin diseases, such as psoriasis, and gas and DNA analysis.

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"Our laser diode emits the shortest wavelength in the world, at 271.8 nanometers (nm), under injection of alternating [electrical] current at room temperature," announced Professor Chiaki Sasaoka, from Nagoya University.

Previous efforts in the development of ultraviolet laser diodes have only managed to achieve emissions up to 336 nm, explains Sasaoka, not reaching the short-wavelength ultraviolet, or UV-C, which is in the range between 200 and 280 nm.


Material quality

To overcome the various problems that had been preventing the manufacture of this UV-C diode, the team used a high quality aluminum nitride (AlN) substrate as a basis to form the layers of the laser diode. The quality of the material was essential, since the lower quality AlN contains a large number of defects, which end up affecting the efficiency of the active layer of the laser diode in converting electrical energy into light energy.

In a laser diode the ‘p-type’ and ‘n-type’ layers are separated by a ‘quantum well’. When an electric current is passed through a laser diode, positively charged openings in the p-type layer and negatively charged electrons in the n-type flow flow to the center to connect, energy in the form of light particles called photons, is released.

The researchers designed quantum so well that it emitted deep UV light. P and N type layers consist of aluminum gallium nitride (AlGaN). The cladding layer, also made of AlGaN, is arranged on both sides of the p and n layers. The layer below the n-type layer contains silicon impurities, a process called doping. Doping is used as a technique to change material properties.

The layer above the p-type layer is subject to distributed polarization doping which touches the layer without adding impurity.

The aluminum content of the p-side layer is designed so that it is highest at the bottom and reduced at the top. The researchers believe that this aluminum gradient increases the flow of positively charged openings. Finally, a top contact layer was added, which consisted of p-type AlGaN magnesium alloy.



The researchers found that the doping of polarization - insertion of elements to change the behavior of the material - of the coating layer on the positive side ensured operation with a "remarkably low operating voltage" of 13.8V, and the emission "of the shortest length of wave reported so far ".

Asahi Kasei Corporation has already taken an interest in the project, and will help researchers develop deep UV lasers to come up with a commercial product.


Bibliography:

Article: A 271.8 nm deep-ultraviolet laser diode for room temperature operation

Authors: Ziyi Zhang, Maki Kushimoto, Tadayoshi Sakai, Naoharu Sugiyama, Leo J. Schowalter, Chiaki Sasaoka, Hiroshi Amano

Magazine: Applied Physics Express

DOI: 10.7567 / 1882 -0786 / ab50e0

Thursday, 23 January 2020

ESA launches the first prototype oxygen extraction plant from the lunar regolith

📷 | ESA

NASA's Artemis mission will mark the return of humans to the moon since the last Apollo mission in 1972. But bringing astronauts to lunar soil is not the ultimate goal of space agencies. Some plans aim to install real permanent lunar bases in order to carry out scientific experiments and test different engineering techniques. One of the essential resources to manage to maintain these inhabited bases is oxygen. Even if the Moon does not have an atmosphere, the regolith that lines its surface contains a lot of oxygen. And to test the technique of extracting oxygen from the regolith, ESA will host the first large-scale prototype factory using this process.

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Last year, researchers published an article on how to extract oxygen from a lunar dust simulator (regolith); now the first prototype oxygen plant will attempt this extraction on a larger scale. If it works, the technology could provide humans with important resources that will aid future lunar missions, and perhaps even allow long-term bases and colonies on the Moon.



“ Having our own facility allows us to focus on producing oxygen, measuring it with a mass spectrometer when it is extracted from the regolith simulator. Being able to acquire oxygen from the resources found on the Moon would obviously be extremely useful for future lunar colonists, both for breathing and for the local production of rocket fuel "explains the chemist Beth Lomax of the University of Glasgow , in Scotland.

Oxygen is the main resource necessary for the establishment of permanent manned lunar bases. Geochemists have developed a way to extract the oxygen contained in the regolith. Credits: ESA

Extract the oxygen from the regolith by electrolysis into molten salt

The installation, located at the European Space Research and Technology Center of the European Space Agency in the Netherlands, will use the technique developed by Lomax and his colleagues. Geochemists know, on the basis of samples of the lunar regolith, that oxygen is really very abundant in this material. Between 40 and 45% of the regolith by weight is oxygen.

Using an exact copy of the lunar regolith made on Earth, called a simulator of the lunar regolith, attempts have been made in the past to figure out how to extract oxygen, with poor results - too complicated, too weak, or destructive of the regolith. The Lomax team has remedied this by using a technique called “molten salt electrolysis”.

The electrolysis in molten salt of the regolith extracts oxygen while producing usable metal residues. Credits: Lomax et al., Planetary and Space Science, 2019

First, the regolith is placed in a mesh basket. Calcium chloride - the electrolyte - is added and the mixture is heated to about 950 degrees Celsius, a temperature that does not melt the material. Then an electric current is applied. This extracts oxygen and migrates the salt to an anode, where it can be easily removed. This technique extracts up to 96% of the oxygen from the regolith; as a bonus, the remaining material from this process is a mixture of metal alloys.

Use materials left over from electrolysis

" This is another useful avenue of research, to see what are the most useful alloys that could be produced from these, and for what type of applications could they be used." Could they be 3D printed directly, for example, or would they require refinement? The precise combination of metals will depend on where, on the Moon, the regolith is mined - there would be significant regional differences, "said Alexandre Meurisse of the European Space Agency.



The current configuration of the system is based on commercial deoxidation plants, where oxygen is only a useless by-product which is discharged. However, as the facility evolves, a means of storing oxygen will be included. The end goal, of course, is to develop a system that could work on the Moon, using a real lunar regolith, not a simulator.


Bibliography:

ESA opens oxygen plant – making air out of moondust

17/01/2020

http://www.esa.int/Enabling_Support/Space_Engineering_Technology/ESA_opens_oxygen_plant_making_air_out_of_moondust


Alzheimer's disease: a crucial mechanism in the fight against the disease has been identified



Alzheimer's disease is a neurodegenerative disease that affects tens of millions of people worldwide today. It is characterized by two lesions: amyloid deposits and tangles of tau protein. Several treatments have been developed in recent years, targeting one or other of these lesions in order to delay the progression of the disease. But recently, researchers have identified a crucial mechanism of the disease: the process by which beta-amyloid causes tau tangles. A discovery that could lead to treatments far more effective than current therapies.

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Alzheimer's disease has long been characterized by the accumulation of two separate proteins in the brain: first beta-amyloid, which builds up in plaques, then tau, which forms toxic tangles that lead to cell death. . However, the way in which beta-amyloid leads to the toxicity of the tau protein has never been precisely known. Now a new study at the University of Alabama in Birmingham seems to describe this missing mechanism.

Published in the journal Science Translational Medicine , the study details a cascade of events. The accumulation of beta-amyloid activates a receptor which responds to a chemical signal from the brain called noradrenaline, commonly known to mobilize the brain and the body for action. Activation of this receptor by both beta-amyloid and norepinephrine stimulates the activity of an enzyme that activates the tau protein and increases the vulnerability of brain cells.


The role of norepinephrine in the virulence of Alzheimer's disease

Essentially, beta-amyloid bypasses the norepinephrine pathway to trigger a toxic build-up of tau, says Qin Wang, a neuropharmacology researcher in the Department of Cell, Developmental and Integrative Biology at the University of Alabama in Birmingham. " We really show that this norepinephrine is a missing piece of the whole Alzheimer's puzzle ."

This cascade explains why so many previous treatments for Alzheimer's disease have failed. Most of the drugs developed in recent decades have targeted the elimination of beta-amyloids. But new research suggests that norepinephrine amplifies the damage caused by this protein. Beta-amyloid itself can kill neurons, but only in very high doses.

Alzheimer's disease is characterized by two types of lesions: the amyloid plaques between the neurons and the tau neurofibrilar lesions (tangles) inside the neurons. Biologists have long missed the link between beta-amyloid and tau. But Wang's team has shown that norepinephrine plays the main role in this process. Credits: Dr Holland


Add norepinephrine and only 1-2% beta-amyloid is needed to kill brain cells in a laboratory can. So with treatments that targeted beta-amyloid but left the norepinephrine pathway intact, there was enough beta-amyloid left to do significant damage. But if the norepinephrine pathway is really crucial for the development of Alzheimer's disease, it suggests new ways of treating the disease.

Towards the development of a drug targeting the norepinephrine pathway

A drug that was developed to treat depression, but too ineffective to be approved, seems to work in this same direction. The drug, idazoxan, which has also been studied in schizophrenia, has already undergone the first clinical tests and has been shown to be safe. Wang is now looking to promote larger clinical trials of idazoxan to see if it can be used to effectively treat Alzheimer's disease at an early stage.

She hopes that in the long term, a drug which will act on this path linked to Alzheimer's disease in a more targeted manner can be developed, in order to minimize the side effects and maximize the effectiveness. Stephen Salloway, professor of psychiatry and neurology at Warren Alpert Medical School at Brown University, says he doesn't think Alzheimer will give in so easily to a new drug targeting the norepinephrine pathway.



“I doubt there is anything simple that will come out of it. I would be shocked if it works . ” Such a drug, however, could be part of a "therapeutic package" of treatments that could potentially advance Alzheimer's disease, he said. “ The goal is to gain a foothold on the biological level, then to develop it. The more goals we have, the greater the impact.”

The binding of beta-amyloid to norepinephrine would be responsible for the toxicity of the tau protein

Wang has a long history of norepinephrine because of its role in complex thinking and behavior. She came across the link with Alzheimer as part of this research. In two strains of mice and in human tissue in their new study, she and her colleagues showed that small pieces of beta-amyloid bind to a norepinephrine receptor, activating the enzyme GSK3-beta and causing the toxicity of tau.

Graphs and microscopic images showing the efficacy of idazoxan (inhibitor of the enzyme GSK3-beta) on the activity of beta-amyloid; it is blocked and cannot bind to norepinephrine, greatly reducing the toxicity of the tau protein. Credits: Fang Zhang et al. 2020

They confirmed this relationship by blocking the receptor with idazoxan in two strains of middle-aged mice for eight weeks. This deactivated the enzyme and prevented tau from becoming toxic. For years, researchers have wondered how beta-amyloids and tau are linked, says Rudolph Tanzi, an expert in molecular genetics of Alzheimer's disease at Massachusetts General Hospital.

Scientists basically assumed that beta-amyloid had caused tau tangles through a complicated chain of events. Then in a 2014 article in Nature , Tanzi and colleagues used cultured human brain cells to reveal a problem with the theory: mice - the main source of research information on Alzheimer's disease - do not have the right form of tau which becomes entangled in humans.

Block the GSk3-beta enzyme to neutralize inflammation

Instead, researchers have shown that in human cells, beta-amyloid directly causes tangles of tau. Tanzi and his colleagues blocked a variety of different enzymes called kinases to try to stop the process. They found two, both of which blocked the GSK3-beta enzyme - the same one that Wang and his colleagues identified in their research.

In 2014, Wang and his team had already shown that 1-Azakenpaullone, an inhibitor of the GSK3-beta enzyme, neutralizes the formation of beta-amyloid responsible for the induction of tau toxicity (in yellow). Credits: R. Tanzi et al. 2014

Tanzi believes that inflammation is a key player in Alzheimer's disease, triggering the cascade that leads to the disease. He previously described beta-amyloid as the match and tangles of tau as brushwood that catches fire. Tanzi says he has unpublished data on dozens of drugs that prevent beta-amyloid from triggering tangles, many of which support what Wang and his colleagues found in their new document.


Bibliography:

β-amyloid redirects norepinephrine signaling to activate the pathogenic GSK3β/tau cascade

Fang Zhang, Mary Gannon, Yunjia Chen, Shun Yan, Sixue Zhang3, Wendy Feng1, Jiahui Tao1, Bingdong Sha, Zhenghui Liu, Takashi Saito, Takaomi Saido, C. Dirk Keene, Kai Jiao, Erik D. Roberson, Huaxi Xu and Qin Wang

Science Translational Medicine  15 Jan 2020:
Vol. 12, Issue 526, eaay6931
DOI: 10.1126/scitranslmed.aay6931