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samsara

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Ultrahigh-strength and ductile superlattice alloys with nanoscale disordered interfaces

By T. Yang 1,2; Y. L. Zhao 1,3; W. P. Li 3; C. Y. Yu 4; J. H. Luan 3; D. Y. Lin 5; L. Fan 6; Z. B. Jiao 6; W. H. Liu 7; X. J. Liu 7,8; J. J. Kai 1,3; J. C. Huang 2,3; C. T. Liu 1,2,3

1 = Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China.
2 = Hong Kong Institute for Advanced Study, City University of Hong Kong, Hong Kong, China.
3 = Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong, China.
4 = College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China.
5 = Software Center for High Performance Numerical Simulation and Institute of Applied Physics and Computational Mathematics, Chinese Academy of Engineering Physics, Beijing, China.

6 = Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong, China.
7 = School of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen, China.
8 = Institute of Materials Genome and Big Data, Harbin Institute of Technology, Shenzhen, China.

* These authors contributed equally to this work.


Science 24 Jul 2020:
Vol. 369, Issue 6502, pp. 427-432
DOI: 10.1126/science.abb6830


Strength through disorder

Jet turbine blades and other objects with ultrahigh strength at high temperatures are made of special alloys that are often grown as costly single crystals to help avoid failure. Yang et al. discovered that adding a small amount of boron in a nickel-cobalt-iron-aluminum-titanium alloy creates an ultrahigh-strength material. Critically, the alloy has a nanoscale-disordered interface in between crystal grains that substantially improves the ductility while preventing high-temperature grain coarsening. This alloy design creates attractive high-temperature properties for various applications.

Science, this issue p. 427


Abstract

Alloys that have high strengths at high temperatures
are crucial for a variety of important industries including aerospace. Alloys with ordered superlattice structures are attractive for this purpose but generally suffer from poor ductility and rapid grain coarsening. We discovered that nanoscale disordered interfaces can effectively overcome these problems. Interfacial disordering is driven by multielement cosegregation that creates a distinctive nanolayer between adjacent micrometer-scale superlattice grains. This nanolayer acts as a sustainable ductilizing source, which prevents brittle intergranular fractures by enhancing dislocation mobilities. Our superlattice materials have ultrahigh strengths of 1.6 gigapascals with tensile ductilities of 25% at ambient temperature. Simultaneously, we achieved negligible grain coarsening with exceptional softening resistance at elevated temperatures. Designing similar nanolayers may open a pathway for further optimization of alloy properties.

 

Grandy

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China’s novel flying robot able to take scientific research to Qinghai-Tibet Plateau

Global Times Published: 2020/9/14 11:13:33


Flying robot "Yunque" developed by Chinese researchers at the Shenyang Institute of Automation Photo: Chinanews.com

A novel flying robot independently developed by Chinese researchers at the Shenyang Institute of Automation is now able to carry out scientific investigation in a high altitude area - the Qinghai-Tibet Plateau in Southwest China, making it the first ever Chinese robot with such capability.

Named "Yunque" (Skylark), the flying robot can fly and land autonomously, fly along the scheduled path, adjust flight altitude automatically according to the landform, and avoid both dynamic and static obstacles in hostile environment, such as the thin air and strong winds on the Qinghai-Tibet Plateau.

The Qinghai-Tibet Plateau is known for its high altitude, thin air and changeable weather, which have posed great difficulties and dangers to scientific investigators. The robot can help reveal the mechanism of the environmental change of the plateau and promote the ecological and environmental protection.

Breaking through the bottleneck of some key technologies, "Yunque" is capable of loading equipment of five kilograms, withstanding moderate gale as well as flying for nearly 30 minutes at an altitude of 6,000 meters above sea level.

In recent examinations, the robot has finished the thermal infrared image monitoring of ice temperature, three-dimensional topographic surveying and modeling, as well as upper atmosphere temperature and humidity pressure monitoring in a glacier area 6,000 meters above sea level.

In another investigation at the Nam Co Lake in Southwest China's Tibet Autonomous Region, "Yunque" has collected deep water samples automatically and monitored the real-time lake water temperature through vertical profile.

Local newspaper Shenyang Daily said the robot can fly to all field stations on the Qinghai-Tibet Plateau and most of the glacier areas on the plateau.

The Shenyang Institute of Automation under the Chinese Academy of Sciences is a cradle of China's robotic technology, focusing on robotics, intelligent manufacturing and opto-electronic information technology.
 

JSCh

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Chinese researchers develop new hazardous compounds screening method
Source: Xinhua| 2020-10-08 18:22:54|Editor: huaxia

BEIJING, Oct. 8 (Xinhua) -- Chinese researchers have developed a new method to improve the screening of hazardous compounds in agricultural products, providing a new strategy for ensuring food safety, according to the Chinese Academy of Agricultural Sciences (CAAS).

Conventional food safety detection methods can only detect one or several types of agricultural and veterinary drugs, and the same sample needs to be analyzed by many different detection methods, which is time-consuming.

Researchers from the Institute of Apicultural Research under the CAAS developed a new integrated data acquisition method based on a high-resolution mass spectrometry platform, which is suitable for high throughput screening of mixed pollutants such as veterinary drugs, pesticides, and mycotoxins in agricultural products.

This method was successfully applied to analyze 180 veterinary drugs in milk, 220 pesticides in tomatoes, and 50 mycotoxins in maize, respectively. Results showed that it achieves a higher rate of identification and lower false results for targeted compounds compared with previous methods.

The method improves the utilization rate of the equipment, avoids repeated data collection, and helps save the screening cost.

The research was published in the Journal of Hazardous Materials.
 
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JSCh

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NEWS RELEASE 8-OCT-2020
Mystery solved: How do tips of plants stay virus-free? | EurekAlert! Science News
UNIVERSITY OF SCIENCE AND TECHNOLOGY OF CHINA

Plants are able to keep growing indefinitely because they have tissues made of meristems--plant stem cells--which have the unique ability to transform themselves into the various specialized cells that make up the plant, dividing whenever appropriate and producing new cells of whatever type as needed. Meristems exist at the tips of all plants, allowing them to grow new stems or new roots, and, in trees, also in the trunk, where they add extra girth.

It has been known since the 1950s that the meristems at the tips of plants, or shoot apical meristems (SAM), have the remarkable ability to remain virus-free as they give birth to their specialized daughter cells, even if the rest of the plant is thoroughly infected by a virus. This happens not just for one or even a few viruses, but a very wide range of them.

This virus-beating ability in perhaps the most important part of a plant has been exploited by scientists and farmers since then in order to cultivate new plants from donor plants that are infected, but without passing on the virus. They simply snip a tiny part of the tip, raise it for a time in a test tube or petri dish, and repeat it several times, the plant cutting typically grows pathogen-free.

Researchers at the University of Science and Technology of China (USTC) have offered new insights into this incredible ability in a new study published on Oct 8th in Science.

The research team inoculated a thale cress plant (Arabidopsis thaliana, related to cabbage and mustard, often used in botanical research as a model organism) with Cucumber Mosaic Virus and watched what happened.

As the virus spread towards the SAM, they noticed that it halted just before it got to a region called the WUSCHEL-expression domain. Taking a very close look at the distribution of the WUSCHEL regulator proteins here, they noticed more had appeared where the virus had tried to establish itself upon inoculation. WUSCHEL is an extremely important protein that plays a key, regulating role in determining stem cell fate, at the early stages of the development of a plant embryo, and also oversees the meristems, maintaining them in an undifferentiated state and specifying what sort of daughter cells they will produce.

Then they inoculated virus directly into the cress's stem cell and just below it, and found that the virus only spread in the latter region. "There's a chemical called dexamethasone that can induce production of these WUSCHEL proteins in our tested plants," said Zhong Zhao, paper author and a professor from the School of Life Science at USTC, "so next, we inoculated more cress with the virus and then gave some of the plants dexamethasone treatment, and some we just left alone." Some 89 percent of the plants without the treatment were infected with the virus, but 90 percent of those with the treatment were free from virus invasion.

How WUSCHEL beat virus? They found surprisingly that the WUSCHEL proteins worked to inhibit production of viral proteins.

Viruses can't make their own proteins, but rather hijack the protein assembly line of an organism and make it produce copies of the virus. The WUSCHEL proteins, which do so much to regulate the SAM, had in essence frozen all protein production--whether by the plant for itself or when hijacked by the virus--thus preventing the viruses from replicating.

Genes similar to those that direct production of WUSCHEL proteins in the thale cress are very widespread across the plant kingdom, so the researchers are interested in seeing "whether this strategy can be applied in breeding to obtain broad-spectrum antiviral crop varieties in the future" says Zhao.
 

JSCh

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NEWS RELEASE 8-OCT-2020
Engineered electrode material moves battery research closer to 'holy grail' | EurekAlert! Science News
UNIVERSITY OF SCIENCE AND TECHNOLOGY OF CHINA

Electric vehicles are gaining in popularity, but their long charging time is a significant detraction for potential customers. While a typical SUV with a combustion engine could travel 300 miles with a five-minute refuel, a state-of-the-art electric vehicle takes about one hour to store enough energy to travel the same distance. The technology for a high-capacity Lithium-ion battery that charges quickly and operates efficiently is still an unrealized goal -- but researchers are now closer than ever.

An international team of researchers published details of an engineered electrode material that allows for such advanced batteries on Oct 8th in Science.

"The combination of high energy, high rate, and long cycle life is the holy grail of battery research, which is determined by one of the key components of the battery: the electrode materials," said Hengxing Ji, professor at the University of Science and Technology of China (USTC). "We aim to search for an electrode material that can make a dent in performance metrics from laboratory research and can hold the promise to stand with the industrial production techniques and requirements."

Energy enters and leaves the battery by electrochemical reactions in electrodes, so efficient and effective Lithium-ion transfer is of the utmost importance, according to first author Hongchang Jin of USTC, especially in transferring the energy from the battery to the device via the anode.

The researchers turned to black phosphorus, a material that has been considered for use in electrodes before but is usually abandoned due to its tendency to deform along its layered edges, making the transfer of Lithium-ions deeply inefficient and rendering a lower quality material. By combining black phosphorus with graphite, the chemical bonds between these two materials stabilize and prevent the problematic edge changes.

The team also tackled another issue hindering the material: Electrolytes can break down into less conductive pieces and build up on the surface of the electrode, inhibiting Lithium-ion transfer into the electrode material, like dust obscuring light through glass. The team applied a thin polymer gel coating to the electrode materials and reinforced the Lithium-ion transport path, effectively preventing the issue.

"The composite anode material restored 80% of its full capacity in less than 10 minutes and shows a 2000-cycle operation life at room temperature, which was measured at conditions compatible with the industrial fabrication processes," said co-first author Sen Xin, professor of the Institute of Chemistry Chinese Academy of Sciences. "If scalable production can be achieved, this material may provide an alternative, updated graphite anode, and move us toward a Lithium-ion battery with energy density of more than 350 watts-hour per kilogram and fast-charging capability. Successful projection of the above parameters onto the electric vehicle will significantly raise its competitiveness against the fuel cars."

The 350 watts-hour per kilogram describes the energy capacity of the battery -- an electric vehicle with such a battery could travel 600 miles on a single charge. For comparison, the on-market Tesla Model S can travel 400 miles on one charge.

With this novel technology, Ji said the researchers plan to pursue both fundamental scientific questions of the Lithium-ion charging-discharging process and industry-related questions on ways to scale composite material production in more mild conditions.

"We will investigate engineering materials of rationally selected structure, but with consideration for price and practicality to achieve an attractive performance," Ji said.
 

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China Science @ChinaScience
China state-affiliated media

Chinese scientists for the 1st time proposed ‘neuromorphic completeness’, which offers a corresponding system hierarchy for neuromorphic computing, providing a promising platform for artificial general intelligence development. https://bit.ly/2H6yyQC

Image
9:00 AM · Oct 16, 2020

 

JSCh

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#中国科学家把微波测量灵敏度提高1000倍#
[中国赞]
】山西大学激光光谱研究所贾锁堂教授和肖连团教授带领团队,在国际上首次实现里德堡原子微波超外差接收机样机,极大提升了微波电场场强的探测灵敏度,微波测量灵敏度达55nV/(cm·Hz1/2),优于之前国际最好水平1000倍,最小可探测微波场强约400pV/cm,优于之前国际最好水平10000倍。​
肖连团教授表示,该项研究成果极大地推动了微波电场精密测量领域的发展,在国防安全、微波通信、量子计量、电子信息等领域具有重要的应用价值。(科技日报记者 王海滨)O我科学家把微波测量灵敏度提高1000倍

Science and Technology Daily
60 minutes ago from Weibo


[Chinese scientists increase the sensitivity of microwave measurement by 1,000 times]

Professor Jia Suotang and Professor Xiao Liantuan from the Institute of Laser Spectroscopy of Shanxi University led the team to realize the Rydberg Atomic Microwave Superheterodyne Receiver prototype for the first time in the world. Which greatly improved the detection sensitivity of microwave electric field strength, and the microwave measurement sensitivity reached 55nV /(cm·Hz1/2), 1000 times better than the previous best international level, and the smallest detectable microwave field strength is about 400pV/cm, which is 10000 times better than the previous best international level.

Professor Xiao Liantuan said that the research results have greatly promoted the development of the field of precision measurement of microwave electric fields and have important application values in the fields of national security, microwave communications, quantum metrology, and electronic information. (Science and Technology Daily reporter Wang Haibin)

 

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