China Science & Technology Forum

[onebyone]

https://twitter.com/x/status/936047804761432064

 

[JSCh]

01 December 2017
GM plant species numbers set to dramatically increase
Chinese scientists combine magnets and nanotech to successfully manipulate pollen. Tim Wallace reports.

Genetic modification of food crops is, depending on your point of view, a wondrous technological solution to feed a growing global population or a hubris-soaked scientific monstrosity sowing the seeds of environmental apocalypse.

Yet the war over GM crops, though intense, has so far been restricted to a small number of battlefields – corn, soybean, tomatoes and canola, for instance – due to the limited list of plant species scientists have been able to successfully modify.

Now the stage may be set for a massive expansion in the theatres of conflict. A team of mostly Chinese scientists has announced a new technique, called pollen magnetofection, which they say overcomes the obstacles of traditional plant-transformation methods and clears the way to genetically modify “almost all crops”.

“At the moment, we are very limited as to which plants, and even types of plants – called cultivars – we are able to transform,” explains Rachel Burton, of the ARC Centre of Excellence in Plant Cell Walls at the University of Adelaide, who was not involved in the research.

“For example, we work with barley a lot, and are only able to make transgenic barley from about 10 cultivars. There are even more we can’t transform at all. This technology would change that.”

Almost all current GM methods involve regenerating a new plant from a single transformed cell using complicated in vitro culture processes. The alternative approach taken by Xiang Zhao, of the Chinese Academy of Agricultural Sciences in Beijing, and colleagues is to first manipulate the DNA of pollen, then use this pollen to fertilise a plant’s ovary and directly generate transgenic seeds.

The team details its methods in the journal Nature Plants.

Their key tool for overcoming the lack of success of previous efforts to genetically transform pollen is pairing magnetofection – the use of magnetic fields to direct foreign DNA to target cells – with nanobio technology, using magnetic nanoparticles to “smuggle” DNA into the heart of the pollen.

Magnetofection has mainly been used in animal science and medical research, as the researchers note in their paper, because the thicker cell walls of plants have proved more resistant to DNA incursions. Zhao and colleagues overcame this resistance by concentrating on pollen’s weakest points – the apertures that are exit points for the release of sperm cells during germination.

The scientists measured the size of these apertures, then chose nanoparticle delivery vehicles small enough to fit through them, transporting DNA cargo into the pollen.

The process is “a ground-breaking step towards eliminating the time-consuming steps of in vitro culture techniques”, says Chris Cazzonelli, of the Environmental Epigenetics Laboratory at Western Sydney University in Australia.

“It opens opportunities to transform new plant species not previously easily amenable to tissue culture or conventional transformation techniques.”

Monika Doblin, an expert on plant cell walls at the University of Melbourne, also in Australia, agrees a genetic transformation technique that can be easily applied to any pollen-producing plant species is a “significant advance”, though she notes the small species sample size and experiment numbers presented in the new paper. “Further investigation as to the effectiveness of this technique across a broad range of current crop species is warranted but, that said, it does sound promising,” she says.

The rewards and any risks, however, are likely to be limited to special cases, says Justin Borevitz, who specialises in food and environmental security at Australian National University in Canberra. “It may not be substantially different to existing agriculture technologies,” he adds. “Another tool for the genomic breeding toolbox.”

Anti-GM activists are nonetheless likely to greet the news with dread, while Burton reckons most plant scientists will see the prospect of more plant experimentation as a good thing.

“We have been doing this for thousands of years, since agriculture got going,” she says. “Usually we do it by conventional breeding.” Not only is this very slow but it brings “all the DNA, both the good and the bad, from both parents, and then you have to spend time getting rid of the bad stuff”. With genetic modification “you can add just the good bit that you want”.

Yet while generally in favour of GM technology and what it can do, Burton acknowledges there are potential issues, too. “We have to be careful we don’t make plants that are weedy, that can take over, wreck ecosystems and push native species out, for example,” she says. “We also have to be sure that we are not making toxic versions of plants – although we can do this by conventional breeding just as easily and with no regulations to stop it.”


GM plant species numbers set to dramatically increase | Cosmos

Xiang Zhao, Zhigang Meng, Yan Wang, Wenjie Chen, Changjiao Sun, Bo Cui, Jinhui Cui, Manli Yu, Zhanghua Zeng, Sandui Guo, Dan Luo, Jerry Q. Cheng, Rui Zhang & Haixin Cui. Pollen magnetofection for genetic modification with magnetic nanoparticles as gene carriers. Nature Plants (2017). DOI: 10.1038/s41477-017-0063-z​

 

[JSCh]

Scientists Visualize Structure of Key DNA Repair Component with ‘Near-Atomic Resolution’
[2017-11-30]

Cells continuously replicate to repair and replace damaged tissue, and each division requires a reprinting of the cell’s genetic blueprints. As the DNA duplicates, errors inevitably occur, resulting in damage that, if left unrepaired, can lead to cellular death. At the first hint of DNA damage, a protein known as an ATR kinase activates the cell’s built-in repair system. Scientists have now imaged this protein at unprecedented resolution, and are beginning to understand its response to DNA damage.

Artist's concept of Launching the cellular DNA-damage response by the ATR-ATRIP complex. /By WANG Guoyan and CHEN Lei, USTC

The researchers published the structural information today in Science.

“The ATR protein is the apical kinase to cope with the DNA damages and replication stress,” said CAI Gang, a professor of life sciences at the University of Science & Technology of China in Hefei, China, and the lead author on the paper. “It has long been a central question to determine the activation mechanism of ATR kinase—how it responds to DNA damage and how it is activated.”

CAI and his team used electron microscopy to image the Mec1-Ddc2 complex at 3.9 ångströms, which is about eight times the size of a single atom of helium. The complex is found in yeast and is the equivalent of the human ATR protein and its cell-signaling protein partner, ATRIP.

The ATR kinase is one of six proteins responsible for maintaining the health of the cell. When this family of proteins identify a problem, such as DNA damage, they instigate the downstream signals needed to repair the damage.

“Cryo-electron microscopy of the Mec1-Ddc2 with state-of-the-art instrumentation has resulted in an electron density map at near-atomic resolution,” said CAI, noting that the improved map has confirmed and expanded upon previous findings.

Three-dimensional structure of the yeast Mec1-Ddc2 complex, a homolog of human ATR-ATRIP. /By WANG Guoyan and MA Yanbing, USTC

ATR has long been a potential therapeutic target, according to CAI. The high-resolution structural information revealed regulatory sites of the ATR kinase, which are poised to activate at the first hint of DNA damage. Elucidating this mechanism could aid in the development of new therapeutics.

“The structure of the yeast member closely resembles those of the human counterpart,” said CAI, drawing attention to the substantial similarity in the detailed architecture. “We believe the information acquired from the yeast Mec1-Ddc2 shed light on the architecture and mechanism of the human ATR-ATRIP complex.”



Scientists Visualize Structure of Key DNA Repair Component with ‘Near-Atomic Resolution’ | USTC Highlights

http://en.ustc.edu.cn/highlight/201712/t20171201_289507.html
Xuejuan Wang, Tingting Ran, Xuan Zhang, Jiyu Xin, Zhihui Zhang, Tengwei Wu, Weiwu Wang, Gang Cai. 3.9 Å structure of the yeast Mec1-Ddc2 complex, a homolog of human ATR-ATRIP. Science (2017). DOI: 10.1126/science.aan8414​

 

[Bussard Ramjet]

Scientists Visualize Structure of Key DNA Repair Component with ‘Near-Atomic Resolution’
[2017-11-30]

Cells continuously replicate to repair and replace damaged tissue, and each division requires a reprinting of the cell’s genetic blueprints. As the DNA duplicates, errors inevitably occur, resulting in damage that, if left unrepaired, can lead to cellular death. At the first hint of DNA damage, a protein known as an ATR kinase activates the cell’s built-in repair system. Scientists have now imaged this protein at unprecedented resolution, and are beginning to understand its response to DNA damage.

Artist's concept of Launching the cellular DNA-damage response by the ATR-ATRIP complex. /By WANG Guoyan and CHEN Lei, USTC

The researchers published the structural information today in Science.

“The ATR protein is the apical kinase to cope with the DNA damages and replication stress,” said CAI Gang, a professor of life sciences at the University of Science & Technology of China in Hefei, China, and the lead author on the paper. “It has long been a central question to determine the activation mechanism of ATR kinase—how it responds to DNA damage and how it is activated.”

CAI and his team used electron microscopy to image the Mec1-Ddc2 complex at 3.9 ångströms, which is about eight times the size of a single atom of helium. The complex is found in yeast and is the equivalent of the human ATR protein and its cell-signaling protein partner, ATRIP.

The ATR kinase is one of six proteins responsible for maintaining the health of the cell. When this family of proteins identify a problem, such as DNA damage, they instigate the downstream signals needed to repair the damage.

“Cryo-electron microscopy of the Mec1-Ddc2 with state-of-the-art instrumentation has resulted in an electron density map at near-atomic resolution,” said CAI, noting that the improved map has confirmed and expanded upon previous findings.

Three-dimensional structure of the yeast Mec1-Ddc2 complex, a homolog of human ATR-ATRIP. /By WANG Guoyan and MA Yanbing, USTC

ATR has long been a potential therapeutic target, according to CAI. The high-resolution structural information revealed regulatory sites of the ATR kinase, which are poised to activate at the first hint of DNA damage. Elucidating this mechanism could aid in the development of new therapeutics.

“The structure of the yeast member closely resembles those of the human counterpart,” said CAI, drawing attention to the substantial similarity in the detailed architecture. “We believe the information acquired from the yeast Mec1-Ddc2 shed light on the architecture and mechanism of the human ATR-ATRIP complex.”



Scientists Visualize Structure of Key DNA Repair Component with ‘Near-Atomic Resolution’ | USTC Highlights

Xuejuan Wang, Tingting Ran, Xuan Zhang, Jiyu Xin, Zhihui Zhang, Tengwei Wu, Weiwu Wang, Gang Cai. 3.9 Å structure of the yeast Mec1-Ddc2 complex, a homolog of human ATR-ATRIP. Science (2017). DOI: 10.1126/science.aan8414​

There is one more Chinese paper published in Science, regarding some dinosaur eggs.

 

[JSCh]

Ancient flying reptiles cared for their young, fossil trove suggests
By Gretchen Vogel
Nov. 30, 2017 , 2:00 PM

A spectacular fossil find is providing tantalizing new clues about the habits of pterosaurs, ancient flying reptiles that lived at the same times as dinosaurs. The cache of more than 200 fossil eggs found with bones of juvenile and adult animals in northwestern China is “one of the most extraordinary fossil [finds] I’ve ever seen,” says David Unwin, a paleontologist at the University of Leicester in the United Kingdom, who was not involved in the work. And it suggests to some researchers that pterosaur parents may have cared for their newly hatched young.

The fossils formed about 120 million years ago when disaster struck a group of pterosaurs. The researchers speculate that when a sudden rain flooded a river, hundreds of pterosaur eggs buried in shallow sand or under a layer of leaves or grass were drowned and washed downstream, along with a number of older individuals. Quickly buried by sediment, the eggs and bones did not decay but instead were preserved as fossils. “You’ve captured the life history of pterosaurs,” Unwin says.

Only a few fossilized pterosaur eggs had turned up before, at sites in Argentina and in China. But in a paper published today in Science, Wang Xiaolin and Jiang Shunxing at the Chinese Academy of Sciences’s Institute of Vertebrate Paleontology and Paleoanthropology in Beijing and their colleagues report that a 3-meter square chunk of rock they excavated in the Turpan-Hami Basin in northwest China contains more than 200 eggs of the pterosaur, called Hamipterus tianshanensis. In 16 of them, researchers have been able to identify fossilized bones of developing embryos.

Whatever transported the eggs to their resting place likely damaged them, so the bones are jumbled and incomplete. But enough is preserved to allow comparisons between the bones in the embryos and those of older pterosaurs also preserved, says Alexander Kellner of the National Museum at the Federal University of Rio de Janeiro in Brazil, who helped analyze the fossils. “It’s amazing,” he says. “We never thought we would find so many eggs.”

This Chinese fossil contains hundreds of pterosaur eggs and bones.
Wang et al., Science, 2017

The researchers used computerized tomography scans to measure some of the embryonic bones and took thin slices of some to tell how mature they were. In one particularly well preserved egg, the hind limbs were more developed than the forelimbs. That suggests, Kellner says, that pterosaurs could walk when they hatched, but not fly. The embryos also appeared to be toothless, unlike some dinosaur embryos. Together, the authors say, the evidence suggests that hatchlings might have not been able to hunt for themselves, relying on their parents to feed them. “They needed some sort of parental care,” Kellner says.

Unwin says he’s not yet convinced. The smallest hatchlings in the sample are 40% bigger than the embryos, he notes, so the forelimbs might have matured by the time they hatched. Charles Deeming, an expert on reptile reproduction at the University of Lincoln in the United Kingdom, also cautions about drawing firm conclusions from close analysis of just a few eggs. Although fossil egg finds are spectacular, he says, “one of the dangers … is that they are often overinterpreted.”

Jiang says that’s a fair critique, but he and others say further analysis of the wealth of eggs at the site will eventually provide firmer evidence one way or another. “The numbers [of eggs and bones] mean that we can move on from positing ideas to testing ideas,” Unwin says. Pterosaur remains scattered through multiple layers of the rocks suggest that the site was a pterosaur nesting site for many years. “It must have been a great place to bury eggs,” Unwin says—until, periodically, catastrophe struck. The specimen described today is only the start, Jiang says. “There are many more eggs.”


Ancient flying reptiles cared for their young, fossil trove suggests | Science | AAAS

###
​

Scientists just discovered the mother lode of pterosaur eggs, and they are over the moon
By Jason Bittel November 30 at 2:00 PM

“Extraordinary.” “Stellar.” “Truly awesome.” “A world-class find.”

That's how paleontologists are reacting to the discovery of several hundred ridiculously well-preserved pterosaur eggs in China, some of them still containing the remains of embryos.

“My first thought was extreme jealousy,” said David Unwin, a pterosaur expert and paleobiologist at the University of Leicester. “Really.”

To understand why Unwin and others are freaking out about the discovery, published Thursday in the journal Science, you have to first appreciate how rare pterosaur eggs are.


--> Scientists just discovered the mother lode of pterosaur eggs, and they are over the moon - The Washington Post

Xiaolin Wang, Alexander W. A. Kellner, Shunxing Jiang, Xin Cheng, Qiang Wang, Yingxia Ma, Yahefujiang Paidoula, Taissa Rodrigues, He Chen, Juliana M. Sayão, Ning Li, Jialiang Zhang, Renan A. M. Bantim, Xi Meng, Xinjun Zhang, Rui Qiu, Zhonghe Zhou. Egg accumulation with 3D embryos provides insight into the life history of a pterosaur. Science (2017). DOI: 10.1126/science.aan2329​

 

[Bussard Ramjet]

Ancient flying reptiles cared for their young, fossil trove suggests
By Gretchen Vogel
Nov. 30, 2017 , 2:00 PM

A spectacular fossil find is providing tantalizing new clues about the habits of pterosaurs, ancient flying reptiles that lived at the same times as dinosaurs. The cache of more than 200 fossil eggs found with bones of juvenile and adult animals in northwestern China is “one of the most extraordinary fossil [finds] I’ve ever seen,” says David Unwin, a paleontologist at the University of Leicester in the United Kingdom, who was not involved in the work. And it suggests to some researchers that pterosaur parents may have cared for their newly hatched young.

The fossils formed about 120 million years ago when disaster struck a group of pterosaurs. The researchers speculate that when a sudden rain flooded a river, hundreds of pterosaur eggs buried in shallow sand or under a layer of leaves or grass were drowned and washed downstream, along with a number of older individuals. Quickly buried by sediment, the eggs and bones did not decay but instead were preserved as fossils. “You’ve captured the life history of pterosaurs,” Unwin says.

Only a few fossilized pterosaur eggs had turned up before, at sites in Argentina and in China. But in a paper published today in Science, Wang Xiaolin and Jiang Shunxing at the Chinese Academy of Sciences’s Institute of Vertebrate Paleontology and Paleoanthropology in Beijing and their colleagues report that a 3-meter square chunk of rock they excavated in the Turpan-Hami Basin in northwest China contains more than 200 eggs of the pterosaur, called Hamipterus tianshanensis. In 16 of them, researchers have been able to identify fossilized bones of developing embryos.

Whatever transported the eggs to their resting place likely damaged them, so the bones are jumbled and incomplete. But enough is preserved to allow comparisons between the bones in the embryos and those of older pterosaurs also preserved, says Alexander Kellner of the National Museum at the Federal University of Rio de Janeiro in Brazil, who helped analyze the fossils. “It’s amazing,” he says. “We never thought we would find so many eggs.”

This Chinese fossil contains hundreds of pterosaur eggs and bones.
Wang et al., Science, 2017

The researchers used computerized tomography scans to measure some of the embryonic bones and took thin slices of some to tell how mature they were. In one particularly well preserved egg, the hind limbs were more developed than the forelimbs. That suggests, Kellner says, that pterosaurs could walk when they hatched, but not fly. The embryos also appeared to be toothless, unlike some dinosaur embryos. Together, the authors say, the evidence suggests that hatchlings might have not been able to hunt for themselves, relying on their parents to feed them. “They needed some sort of parental care,” Kellner says.

Unwin says he’s not yet convinced. The smallest hatchlings in the sample are 40% bigger than the embryos, he notes, so the forelimbs might have matured by the time they hatched. Charles Deeming, an expert on reptile reproduction at the University of Lincoln in the United Kingdom, also cautions about drawing firm conclusions from close analysis of just a few eggs. Although fossil egg finds are spectacular, he says, “one of the dangers … is that they are often overinterpreted.”

Jiang says that’s a fair critique, but he and others say further analysis of the wealth of eggs at the site will eventually provide firmer evidence one way or another. “The numbers [of eggs and bones] mean that we can move on from positing ideas to testing ideas,” Unwin says. Pterosaur remains scattered through multiple layers of the rocks suggest that the site was a pterosaur nesting site for many years. “It must have been a great place to bury eggs,” Unwin says—until, periodically, catastrophe struck. The specimen described today is only the start, Jiang says. “There are many more eggs.”


Ancient flying reptiles cared for their young, fossil trove suggests | Science | AAAS

###
​

Scientists just discovered the mother lode of pterosaur eggs, and they are over the moon
By Jason Bittel November 30 at 2:00 PM

“Extraordinary.” “Stellar.” “Truly awesome.” “A world-class find.”

That's how paleontologists are reacting to the discovery of several hundred ridiculously well-preserved pterosaur eggs in China, some of them still containing the remains of embryos.

“My first thought was extreme jealousy,” said David Unwin, a pterosaur expert and paleobiologist at the University of Leicester. “Really.”

To understand why Unwin and others are freaking out about the discovery, published Thursday in the journal Science, you have to first appreciate how rare pterosaur eggs are.


--> Scientists just discovered the mother lode of pterosaur eggs, and they are over the moon - The Washington Post

Xiaolin Wang, Alexander W. A. Kellner, Shunxing Jiang, Xin Cheng, Qiang Wang, Yingxia Ma, Yahefujiang Paidoula, Taissa Rodrigues, He Chen, Juliana M. Sayão, Ning Li, Jialiang Zhang, Renan A. M. Bantim, Xi Meng, Xinjun Zhang, Rui Qiu, Zhonghe Zhou. Egg accumulation with 3D embryos provides insight into the life history of a pterosaur. Science (2017). DOI: 10.1126/science.aan2329​

One thing I don't understand is why the Chinese scientist collaborated with Brazilians in this paper.

Any insights?

 

[JSCh]

One thing I don't understand is why the Chinese scientist collaborated with Brazilians in this paper.

Any insights?

No idea.

 

[Bussard Ramjet]

No idea.

In fact it seems that these Brazilian Scientists collaborate regularly with Chinese. I have just seen other papers with the same group.

Also, I widely underestimated the impact of this find. It turns out that this is one of the biggest finds in Paleontology. Twitter and all news media is full of this paper.

Also, here is the twitter handle of one of the Brazilian scientists: @paleotaissa

 

[Han Patriot]

Ancient flying reptiles cared for their young, fossil trove suggests
By Gretchen Vogel
Nov. 30, 2017 , 2:00 PM

A spectacular fossil find is providing tantalizing new clues about the habits of pterosaurs, ancient flying reptiles that lived at the same times as dinosaurs. The cache of more than 200 fossil eggs found with bones of juvenile and adult animals in northwestern China is “one of the most extraordinary fossil [finds] I’ve ever seen,” says David Unwin, a paleontologist at the University of Leicester in the United Kingdom, who was not involved in the work. And it suggests to some researchers that pterosaur parents may have cared for their newly hatched young.

The fossils formed about 120 million years ago when disaster struck a group of pterosaurs. The researchers speculate that when a sudden rain flooded a river, hundreds of pterosaur eggs buried in shallow sand or under a layer of leaves or grass were drowned and washed downstream, along with a number of older individuals. Quickly buried by sediment, the eggs and bones did not decay but instead were preserved as fossils. “You’ve captured the life history of pterosaurs,” Unwin says.

Only a few fossilized pterosaur eggs had turned up before, at sites in Argentina and in China. But in a paper published today in Science, Wang Xiaolin and Jiang Shunxing at the Chinese Academy of Sciences’s Institute of Vertebrate Paleontology and Paleoanthropology in Beijing and their colleagues report that a 3-meter square chunk of rock they excavated in the Turpan-Hami Basin in northwest China contains more than 200 eggs of the pterosaur, called Hamipterus tianshanensis. In 16 of them, researchers have been able to identify fossilized bones of developing embryos.

Whatever transported the eggs to their resting place likely damaged them, so the bones are jumbled and incomplete. But enough is preserved to allow comparisons between the bones in the embryos and those of older pterosaurs also preserved, says Alexander Kellner of the National Museum at the Federal University of Rio de Janeiro in Brazil, who helped analyze the fossils. “It’s amazing,” he says. “We never thought we would find so many eggs.”

This Chinese fossil contains hundreds of pterosaur eggs and bones.
Wang et al., Science, 2017

The researchers used computerized tomography scans to measure some of the embryonic bones and took thin slices of some to tell how mature they were. In one particularly well preserved egg, the hind limbs were more developed than the forelimbs. That suggests, Kellner says, that pterosaurs could walk when they hatched, but not fly. The embryos also appeared to be toothless, unlike some dinosaur embryos. Together, the authors say, the evidence suggests that hatchlings might have not been able to hunt for themselves, relying on their parents to feed them. “They needed some sort of parental care,” Kellner says.

Unwin says he’s not yet convinced. The smallest hatchlings in the sample are 40% bigger than the embryos, he notes, so the forelimbs might have matured by the time they hatched. Charles Deeming, an expert on reptile reproduction at the University of Lincoln in the United Kingdom, also cautions about drawing firm conclusions from close analysis of just a few eggs. Although fossil egg finds are spectacular, he says, “one of the dangers … is that they are often overinterpreted.”

Jiang says that’s a fair critique, but he and others say further analysis of the wealth of eggs at the site will eventually provide firmer evidence one way or another. “The numbers [of eggs and bones] mean that we can move on from positing ideas to testing ideas,” Unwin says. Pterosaur remains scattered through multiple layers of the rocks suggest that the site was a pterosaur nesting site for many years. “It must have been a great place to bury eggs,” Unwin says—until, periodically, catastrophe struck. The specimen described today is only the start, Jiang says. “There are many more eggs.”


Ancient flying reptiles cared for their young, fossil trove suggests | Science | AAAS

###
​

Scientists just discovered the mother lode of pterosaur eggs, and they are over the moon
By Jason Bittel November 30 at 2:00 PM

“Extraordinary.” “Stellar.” “Truly awesome.” “A world-class find.”

That's how paleontologists are reacting to the discovery of several hundred ridiculously well-preserved pterosaur eggs in China, some of them still containing the remains of embryos.

“My first thought was extreme jealousy,” said David Unwin, a pterosaur expert and paleobiologist at the University of Leicester. “Really.”

To understand why Unwin and others are freaking out about the discovery, published Thursday in the journal Science, you have to first appreciate how rare pterosaur eggs are.


--> Scientists just discovered the mother lode of pterosaur eggs, and they are over the moon - The Washington Post

Xiaolin Wang, Alexander W. A. Kellner, Shunxing Jiang, Xin Cheng, Qiang Wang, Yingxia Ma, Yahefujiang Paidoula, Taissa Rodrigues, He Chen, Juliana M. Sayão, Ning Li, Jialiang Zhang, Renan A. M. Bantim, Xi Meng, Xinjun Zhang, Rui Qiu, Zhonghe Zhou. Egg accumulation with 3D embryos provides insight into the life history of a pterosaur. Science (2017). DOI: 10.1126/science.aan2329​

200 eggs are a crazy find.

 

[Martian2]

One thing I don't understand is why the Chinese scientist collaborated with Brazilians in this paper.

Any insights?

Brazil is an important supplier of iron ore to China.

China has collaboration projects with important trade partners to build people-to-people bridges between countries.

 

[JSCh]

Public Release: 4-Dec-2017
Better mastery of heat flow leads to next-generation thermal cloaks
Chinese physicists manipulate the transfer of thermal energy as a means of reducing heat waste, using thermal camouflage tactics
Springer

Ever heard of the invisibility cloak? It manipulates how light travels along the cloak to conceal an object placed behind it. Similarly, the thermal cloak is designed to hide heated objects from infrared detectors without distorting the temperature outside the cloak. Materials for such cloaks would need to offer zero thermal conductivity to help camouflage the heat. Now, Liujun Xu and colleagues from Fudan University, Shanghai, China, have explored a new mechanism for designing such materials. These findings published in EPJ B could have implications for manipulating the transfer of thermal energy as a way to ultimately reduce heat waste from fossil fuels and help mitigate energy crises.

In this work, for the first time the authors experimentally verify that the inner composition of materials, which presents a non-uniform periodic structure, can exhibit quasi-uniform heat conduction. To do so, they use an infrared camera to detect heat in experimental samples placed between a hot and cold bath. These results confirm their own equations predicting the thermal conductivity of the periodic material.

To achieve the desired thermal illusion, they rely on quasi-uniform heat conduction. Instead of producing an omnidirectional illusion, showing objects with the same temperature signature regardless of the angle of observation, the authors introduce what they refer to as the Janus thermal illusion. It features an object whose heat is not detectable from one direction, thus forming an invisible illusion. By contrast, it features a different heat signature than its actual signature along the vertical axis, thus forming a different type of illusion, which is visible but not displaying the reality.

To remove the influence of thermal convection and radiation from their experimental results, the authors also perform simulations. These in turn help to develop the concept of 'illusion thermal diodes', which approach thermal illusion as an additional degree of freedom for heat management. Ultimately, these diodes could be applied in fields that require both thermal camouflage and thermal rectification.

###​

Reference: L. Xu, C. Jiang, J. Shang, R. Wang and J. Huang (2017), Periodic composites: Quasi-uniform heat conduction, Janus thermal illusion, and illusion thermal diodes, European Physical Journal B 90: 221, DOI: 10.1140/epjb/e2017-80524-6


Better mastery of heat flow leads to next-generation thermal cloaks | EurekAlert! Science News

 

[JSCh]

Public Release: 5-Dec-2017
Working in the cold
High-rate and long-life lithium-ion battery with improved low-temperature performance through a prelithiation strategy
Wiley

When it is cold in winter, cars tend to have starting problems. This is not much better with electric cars, which inevitably lose capacity of their rechargeable lithium-ion batteries at freezing temperatures. Now, Chinese scientists have offered a strategy to avoid plunging battery kinetics. In a study published in the journal Angewandte Chemie, they designed a battery system with a cold-enduring hard-carbon anode and a powerful lithium-rich cathode, with the important initial lithiation step integrated.

"Non-graphitizable" or "hard" carbon is a promising, low-cost anode material in battery technology. Even at low temperatures, it exhibits fast intercalation kinetics of lithium ions. During charging/discharging of a battery cell, lithium ions migrate from the cathode through an electrolyte to the anode and vice versa. If the anodic material, which is often graphite, contains prestored lithium, the volume change by the incoming lithium ions is leveled out to ensure a longer cell life and faster charge/discharge kinetics. Prelithiated hard carbon has been proven as a robust material in lithium-ion capacitors. However, the prelithiation process, which involves a pure lithium electrode, is complicated and expensive. Alternative prelithiation strategies are therefore favored by Yonggang Wang and his team at Fudan University, Shanghai, China.

Instead of the extra lithium electrode, they introduced a lithium-rich vanadium phosphate electrode both for lithiation and normal battery operation. The cathode loses some of its lithium ions to the anode in the first charging process where they are intercalated and stored. Then, the scientists combined the lithium-reduced vanadium phosphate cathode and the prelithiated hard-carbon anode (Li(x)C) to form a working lithium-ion battery system. This full cell "keeps the high energy density characteristics of conventional lithium-ion batteries and exhibits the supercapacitor-like high power and long cycle life," the scientists explained. Moreover, it keeps about two-thirds of its capacity at temperatures as low as minus 40 degrees Celsius. Conventional lithium-ion batteries retain only 10 percent. "This achievement arises from the inherent low-temperature ability of the vanadium phosphate cathode and the fast kinetics of the prelithiated hard-carbon anode," said the authors. Many further tests showed that these batteries fulfilled the other parameters of electrochemical cells.

A flaw, still, is the electrolyte that loses conductivity under extremely cold conditions. If this point is solved, this system might provide an attractive design for best performance, winter-enduring electric car engines.


Working in the cold | EurekAlert! Science News

Yao Liu , Bingchang Yang , Xiaoli Dong , Yonggang Wang , Yongyao Xia. A Simple Prelithiation Strategy To Build a High-Rate and Long-Life Lithium-Ion Battery with Improved Low-Temperature Performance, Angewandte Chemie International Edition (2017). DOI: 10.1002/anie.201710555​

 

[JSCh]

Earliest example of large hydraulic enterprise excavated in China
December 5, 2017 by Bob Yirka

​

Map of the Liangzhu city and hydraulic system, Lower Yangtze River, China Credit: PNAS

(Phys.org)—A team of researchers from several institutions in China has uncovered one of the largest water management projects in the ancient world in what is now a part of the eastern coast of modern China. In their paper published in Proceedings of the National Academy of Sciences, the group describes their finding and compares it to other ancient water management systems.

Over 5000 years ago, people living in the Yangtze River Delta apparently grew weary of the flooding that periodically destroyed their crops. They embarked on what became one of the largest water management projects in the ancient world, moving earth and piling it in desired ways to change over 10,000 hectares of landscape to suit their needs. The researchers at the site have been working for four years uncovering the large hydraulic system that was built to support Liangzhu Ancient City.

The researchers report that laborers spent years digging up dirt to make canals, piled it to make dams, and even installed a system of gates to control movement of the water. The result was a system able to prevent normal flooding and to irrigate crops during dry times with rainwater saved in large reservoirs. They also dug canals to allow small boats to carry people and materials around the area. The researchers estimate that it took approximately 3000 people working for eight years just to build one of the larger dams, and in the process, they moved approximately 10 million cubic feet of earth.

(A) Well-preserved 'sand bags', with the knots still clearly visible, the grass plants used are Triarrhena lutarioriparia. (B) A small proportion of rice remains discovered from the storage pit excavated at eastern Mojiaoshan, depth of the boxes around 10 cm. Credit: PNAS

Prior research has dated Liangzhu Ancient City to approximately 5,300 to 4,300 years ago, which would make the water engineering effort one of the oldest in the world. The newer research work demonstrates that use of such technology began in China earlier than had been thought. And it occurred in a relatively isolated location—the water system was not part of empire building; it was constructed to service the needs of a single city. Sadly, prior evidence has also revealed that their efforts were not sufficient to prevent the entire area from being massively flooded approximately 4,200 years ago, leaving behind a meter-thick layer of clay—the devastation was so great the city never recovered, and those that survived migrated to other areas.

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(A) Structure of the Meirendi bank with wooden planks still standing upright. (B) The Bianjiashan pier, wooden stakes still were preserved, forming a T shape. Credit: PNAS

More information: Bin Liu et al. Earliest hydraulic enterprise in China, 5,100 years ago, Proceedings of the National Academy of Sciences (2017). DOI: 10.1073/pnas.1710516114

Abstract
Here we present one of the world's oldest examples of large-scale and formalized water management, in the case of the Liangzhu culture of the Yangtze Delta, dated at 5,300–4,300 years cal B.P. The Liangzhu culture represented a peak of early cultural and social development predating the historically recorded Chinese dynasties; hence, this study reveals more about the ancient origins of hydraulic engineering as a core element of social, political, and economic developments. Archaeological surveys and excavations can now portray the impressive extent and structure of dams, levees, ditches, and other landscape-transforming features, supporting the ancient city of Liangzhu, with an estimated size of about 300 ha. The results indicate an enormous collective undertaking, with unprecedented evidence for understanding how the city, economy, and society of Liangzhu functioned and developed at such a large scale. Concurrent with the evidence of technological achievements and economic success, a unique relationship between ritual order and social power is seen in the renowned jade objects in Liangzhu elite burials, thus expanding our view beyond the practicalities of water management and rice farming.
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https://phys.org/news/2017-12-earliest-large-hydraulic-enterprise-excavated.html

 

[JSCh]

Scientists used diamond tips to apply enormous pressure to a superconducting alloy. Credit: Max Alexander/SPL

06 December 2017
Super-squeezing can’t crush this superconductor’s powers
Material shrugs off pressures similar to those at Earth’s core.

An exotic alloy conducts electricity when subjected to extreme pressures that would be expected to crush the material’s structure and destroy its electrical properties.

The alloy is a superconductor, a material that offers no resistance to the passage of an electrical current. Such materials are valuable for fabricating specialized magnets and other technology. But extreme pressures distort their atomic arrangements, disrupting their ability to carry current.

Liling Sun at the Chinese Academy of Sciences in Beijing, Robert Cava at Princeton University in New Jersey and their colleagues subjected samples of the alloy to pressures of up to 190 gigapascals — nearly 2 million times the atmospheric pressure at sea level — about the level in Earth’s outer core. The alloy’s superconductivity persisted. That contradicts scientists’ understanding of how such materials should behave, providing a challenge to superconducting theory, the authors say.

Proc. Natl Acad. Sci. USA (2017)



Super-squeezing can’t crush this superconductor’s powers : Research Highlights | Nature

 

[JSCh]

New SLM 3D printing technique can produce strong, ductile stainless steel parts
Dec 11, 2017 | By Benedict

A joint research team from the UK, Sweden, and China has developed a new stainless steel SLM 3D printing technique that results in high levels of strength and ductility. The process could be used to make heavy-duty parts for the aerospace and automotive sectors.

While users of plastic 3D printers have found plenty of success printing rubbery and stretchy objects using flexible 3D printer filaments, achieving ductility in the metal 3D printing world has proven rather more difficult.

The general outlook seems to be that one can’t additively manufacture a metal part that has high levels of both strength and ductility, since one trait normally compromises the other. Strong 3D printed metal parts therefore tend to be rigid and brittle—fine for many applications, but not for all.

But sometimes the key to unlocking a breakthrough is collaboration, and researchers from three universities across the world—the University of Birmingham, UK; Stockholm University, Sweden; and Zhejiang University, China—recently came together to develop a new metal 3D printing process that overcomes the additive manufacturing strength-ductility bottleneck.

Their new Selective Laser Melting (SLM) technique, which also enables the printing of “previously inaccessible shapes,” offers an ultrafast cooling rate—1000°C per second to 100 million °C per second—which leads to some highly desirable mechanical results, which could make 3D printed stainless steels a more attractive proposition to manufacturers of cars and aircraft, amongst other things.

The technique's rapid cooling rate, which could not have been achieved with a metal production process besides additive manufacturing, puts the metal into a non-equilibrium state. This can produce microstructures like a sub-micro-sized dislocation network, which in turn results in desirable mechanical properties like strength and ductility.

Ultimately, this dislocation network means greater flexibility for engineers who need complex metal shapes that aren’t necessarily rigid or brittle.

"This work gives researchers a brand new tool to design new alloy systems with ultra-mechanical properties,” says Dr. Leifeng Liu, lead author, who recently moved to the University of Birmingham from Stockholm University as an AMCASH research fellow. “It also helps metal 3D printing to gain access into the field where high mechanical properties are required—like structural parts in aerospace and automotive.”

Liu’s University of Birmingham team—Dr. Yu-Lung Chiu, Dr. Ji Zou, and Dr. Jing Wu, all of whom are part of the university’s School of Metallurgy and Materials—were responsible for establishing a micro and nano material testing system inside electron microscopes, allowing the researchers to analyze the performance of the 3D printed metal sample during mechanical tests.

This testing system reportedly helped the researchers understand the physical mechanisms at play, and to identify effective microstructural features of the printed metals.

The researchers’ study, “Dislocation network in additive manufactured steel breaks strength–ductility trade-off,” has been published in Materials Today.


3ders.org - New SLM 3D printing technique can produce strong, ductile stainless steel parts | 3D Printer News & 3D Printing News

Leifeng Liu, Qingqing Ding, Yuan Zhong, Ji Zou, Jing Wu, Yu-Lung Chiu, Jixue Li, Ze Zhang, Qian Yu, Zhijian Shen. Dislocation network in additive manufactured steel breaks strength–ductility trade-off. Materials Today (2017). DOI: https://doi.org/10.1016/j.mattod.2017.11.004​