China Science & Technology Forum

[JSCh]

First performance test of a 30 mm iron-based superconductor single pancake coil under a 24 T background field
Dongliang Wang1,2,5, Zhan Zhang3,5, Xianping Zhang1,2, Donghui Jiang4, Chiheng Dong1, He Huang1,2, Wenge Chen4, Qingjin Xu3,6 and Yanwei Ma1,2,6

Published 8 March 2019 • © 2019 IOP Publishing Ltd
Superconductor Science and Technology, Volume 32, Number 4

Abstract
A 30 mm inner diameter iron-based superconductor (IBS) single pancake coil (SPC) was firstly fabricated and tested under a 24 T background field. This SPC was successfully made using the seven-filamentary Ba1−xKxFe2As2 (Ba122) tape by the wind-and-react method. This IBS coil shows the highest I c value at a magnetic field reported so far. For example, the transport critical current of this Ba122 SPC achieved 35 A at 4.2 K and 10 T, which is about half of that of a short sample. This indicates that the non-insulation winding process together with the stainless steel tape is suitable for an IBS. Even more encouraging is the fact that the I c of this SPC is still as high as 26 A under a 24 T background field, which is still about 40% of that at zero external magnetic field. These results clearly demonstrate that IBSs are very promising for high-field magnet applications.


First performance test of a 30 mm iron-based superconductor single pancake coil under a 24 T background field - IOPscience

2019 ESAS Award for Excellence in Applied Superconductivity

Prof. Yanwei Ma
Institute of Electrical Engineering, Chinese Academy of Sciences
Beijing, China​

The 2019 ESAS Award for Excellence in Applied Superconductivity will be bestowed to Prof. Dr. Yanwei Ma from the Institute of Electrical Engineering, Chinese Academy of Sciences in Beijing to acknowledge his outstanding contributions to the development of superconductive wires with potentially very high impact for applications. Based on key fundamental insight and understanding of superconducting properties of materials and envisioning their potential, he designed the required, often novel, technologies for their processing. Outstanding in recent years are the innovative concepts developed for the processing and manufacture of Fe-based superconductors, with their robustness to high magnetic fields and their small electromagnetic anisotropy. Upon tailoring appropriate powder-in-tube processing technologies, wires could be processed with in-field critical currents exceeding the widely accepted threshold for practical application, reaching new milestones.


2019 ESAS Award for Excellence in Applied Superconductivity – The European Society of Applied Superconductivity

 

[JSCh]

AUGUST 8, 2019
New perovskite material shows early promise as an alternative to silicon
by Okinawa Institute of Science and Technology

To minimize the loss of electrons from CsPbI3 (red, central layer) into adjacent layers, it is important that the energy levels (eV, on the graph) of all layers are similar. Credit: OIST

Silicon dominates solar energy products—it is stable, cheap and efficient at turning sunlight into electricity. Any new material taking on silicon must compete and win on those grounds. As a result of an international research collaboration, Shanghai Jiao Tong University, the Ecole Polytechnique Fédérale de Lausanne (EPFL), and the Okinawa Institute of Science and Technology Graduate University (OIST) have found a stable material that efficiently creates electricity—which could challenge silicon hegemony.

Writing in Science, the collaborating teams show how the material CsPbI3 has been stabilized in a new configuration capable of reaching high conversion efficiencies. CsPbI3 is an inorganic perovskite, a group of materials gaining popularity in the solar world due to their high efficiency and low cost. This configuration is noteworthy as stabilizing these materials has historically been a challenge.

"We are pleased with results suggesting that CsPbI3 can compete with industry-leading materials," says Professor Yabing Qi, head of OIST's Energy Materials and Surface Sciences Unit, who led on the surface science aspect of the study.

"From this preliminary result we will now work on boosting the material's stability—and commercial prospects."

Energy level alignment
CsPbI3 is often studied in its alpha phase, a well-known configuration of the crystal structure appropriately known as the dark phase because of its black color. This phase is particularly good at absorbing sunlight. Unfortunately, it is also unstable—and the structure rapidly degrades into a yellowish form, less able to absorb sunlight.

This study instead explored the crystal in its beta phase, a less well-known arrangement of the structure that is more stable than its alpha phase. While this structure is more stable, it shows relatively low power conversion efficiency.

This low efficiency partly results from the cracks that often emerge in thin-film solar cells. These cracks induce the loss of electrons into adjacent layers in the solar cell—electrons that can no longer flow as electricity. The team treated the material with a choline iodide solution to heal these cracks, and this solution also optimized the interface between layers in the solar cell, known as energy level alignment.

"Electrons naturally flow to materials with lower potential energy for electrons, so it is important that the adjacent layers' energy levels are similar to CsPbI3," says Dr. Luis K. Ono, a co-author from Professor Qi's lab. "This synergy between layers results in fewer electrons being lost—and more electricity being generated."

The OIST team, supported by the OIST Technology Development and Innovation Center, used ultraviolet photoemission spectroscopy to investigate the energy level alignment between CsPbI3 and the adjacent layers. These data showed how electrons can then move freely through the different layers, generating electricity.

The results showed a low loss of electrons to adjacent layers following treatment with choline iodide —due to better energy level alignments between the layers. By repairing the cracks that naturally emerge, this treatment led to an increase in conversion efficiency from 15 percent to 18 percent.

While that leap may seem small, it brings CsPbI3 into the realm of certified efficiency, the competitive values offered by rival solar materials. Although this early result is promising, inorganic perovskite is still lagging. For CsPbI3 to truly compete with silicon, the team will next work on the trinity of factors allowing silicon's reign to continue—stability, cost, and efficiency.


New perovskite material shows early promise as an alternative to silicon | TechXplore

Yong Wang, M. Ibrahim Dar, Luis K. Ono, Taiyang Zhang, Miao Kan, Yawen Li, Lijun Zhang, Xingtao Wang, Yingguo Yang, Xingyu Gao, Yabing Qi, Michael Grätzel, Yixin Zhao. Thermodynamically stabilized β-CsPbI3–based perovskite solar cells with efficiencies >18%. Science (2019). DOI: 10.1126/science.aav8680​

 

[JSCh]

Physics - Synopsis: Hydrodynamic Cloaks
August 13, 2019

Two separate groups have designed structures that can hide objects from fluid flows and surface waves so that no wake is visible.

J. Park et al., Phys. Rev. Lett. (2019)

What do you get when you cross Harry Potter with Aquaman? An invisibility cloak that works in water, of course. Physicists have taken steps towards this sci-fi mashup with two structural systems that direct fluid flow around an object. The first cloak is a ring of small pillars that deflects incoming fluid in such a way that there is zero drag in the middle of the ring. The second cloak is a pair of thin platforms that funnels waves around objects inside a water channel.

Electromagnetic cloaks—which appeared more than a decade ago—rely on complex structures called metamaterials that bend light waves in ways that traditional materials cannot. Metamaterials can also be designed to work with other wave phenomena, such as sound and heat. As far as fluids are concerned, previous attempts at a hydrodynamical cloak have required active elements, such as micropumps (see 11 August 2011 Synopsis).

Juhyuk Park from Seoul National University in South Korea and colleagues have devised a passive cloak that doesn’t require any input energy. The team first calculated the type of metamaterial needed to cancel the drag on a small obstacle sitting in a sheet of slow-moving fluid. The resulting design is a circular “maze” consisting of 523 pillars that direct flow away from the central region—where the obstacle is located. In experiments, the researchers placed a cylinder inside the cloak and observed how flowing water detoured around the object without generating any downstream wake. With further improvement, such a device could reduce the drag on ships or submarines.

For their passive hydrodynamic cloak, a team of researchers from Zhejiang University and Xiamen University in China had a different aim: reduce the amplitude of water waves inside a channel. The team took inspiration from waveguide cloaks, which use gradient index metamaterials (GIMs) to convert light waves into narrow “trapped modes” that can avoid obstacles in optical waveguides. The researchers installed two thin platforms along the sidewalls of a 60-m-long wave tank. The platforms acted like GIMs by creating shallow regions where waves travel more slowly. In tests with a broad range of wave frequencies, the team found that incoming plane waves converted to trapped modes above the platforms, leaving the middle of the tank nearly wave-free. The team imagines installing such a system in a port or wharf to protect ships.

This research is published in Physical Review Letters.

–Michael Schirber
Michael Schirber is a Corresponding Editor for Physics based in Lyon, France.

Broadband Waveguide Cloak for Water Waves
Siyuan Zou, Yadong Xu, Razafizana Zatianina, Chunyang Li, Xu Liang, Lili Zhu, Yongqiang Zhang, Guohua Liu, Qing Huo Liu, Huanyang Chen, and Zhenyu Wang

Phys. Rev. Lett. 123, 074501 (2019)
Published August 13, 2019

Hydrodynamic Metamaterial Cloak for Drag-Free Flow
Juhyuk Park, Jae Ryoun Youn, and Young Seok Song

Phys. Rev. Lett. 123, 074502 (2019)
Published August 13, 2019​

 

[JSCh]

NEWS * 17 JULY 2019
World’s most invasive mosquito nearly eradicated from two islands in China
Researchers combined sterilization with a bacterium in an attempt to stamp out the Asian tiger mosquito.

Giorgia Guglielmi

Researchers have all but obliterated populations of the world’s most invasive mosquito species — the Asian tiger mosquito (Aedes albopictus) — on two islands in the Chinese city of Guangzhou.

They reduced A. albopictus populations by up to 94% using a combination of two promising control techniques in a field trial for the first time. The two-pronged approach1, published in Nature on 17 July, integrates the sterilization of female Asian tiger mosquitoes with the infection of males using Wolbachia pipientis, a bacterium that hinders the insects’ ability to reproduce and transmit disease-causing viruses such as dengue and Zika.

This resulted in one of the most successful eradication trials of A. albopictus to date, says Peter Armbruster, a mosquito ecologist at Georgetown University in Washington DC, who wrote a commentary to accompany the study. Used in tandem with other control methods such as pesticides, the dual approach could be a very powerful tool, he says.

Problems with control
Previous studies have shown that X-ray sterilization of large numbers of male pests like screw worms (Cochliomyia hominivorax), followed by their release into target areas, can reduce the size of wild pest populations. But this is an inefficient way to control mosquitoes because even though irradiated males can still mate, they are less successful than their unaltered counterparts.

In an alternative approach, workers infect laboratory mosquitoes with strains of Wolbachia, which is found naturally in several insect species, including A. albopictus. When male mosquitoes infected with a certain combination of Wolbachia strains mate with wild females carrying a different combination, the insects can’t produce offspring.

But it’s crucial that only male mosquitoes infected with that particular combination are released into the wild, says Zhiyong Xi, a medical entomologist at Michigan State University in East Lansing, who led the study. If females with those strains are also released, they could mate and produce offspring with males carrying the same Wolbachiacocktail. Their offspring could eventually replace the local mosquito population, making future control attempts that rely on Wolbachia infection more difficult.

To prevent this from happening, facilities that rear large numbers of mosquitoes for control purposes usually separate males from females mechanically, based on size differences. But this process isn’t perfect, Xi says, so workers have to do a second, manual screening to remove female mosquitoes. It’s a tedious and time-consuming task that limits the total number of mosquitoes that can be released. So Xi and his team set out to eliminate the need for this process.

An issue of scale
Wild populations of A. albopictus are naturally infected with two strains of Wolbachia. The researchers infected wild mosquitoes with a third strain of Wolbachia to produce a laboratory colony of the insects with three bacterial variants. Then, the team exposed the colony to low levels of radiation that sterilized the females but only slightly reduced the males’ ability to mate.

During the mosquitoes’ peak breeding seasons in 2016 and 2017, the researchers released more than 160,000 of these mosquitoes per hectare each week in residential areas on two islands situated in a river in Guangzhou — the city with the highest rate of dengue transmission in China.

Their hope was that this would vastly reduce the mosquito population because wild females that mated with the altered males — and wild males that mated with sterile lab females — wouldn’t produce offspring. The team tracked population declines in adult female mosquitoes, since they’re the ones that bite people and transmit diseases. And as expected, the average numbers of wild adult females fell by 83% in 2016 and by 94% in 2017.

Male Asian tiger mosquitoes carrying three strains of Wolbachia await release into a test site.Credit: Yajun Wang

“That’s very impressive,” says Stephen Dobson, a medical entomologist at the University of Kentucky in Lexington, and the founder of MosquitoMate, a company that commercializes Wolbachia as a tool to control the Asian tiger mosquito.

Current strategies for controlling A. albopictus — including spraying pesticides and removing water-filled containers where the insects lay their eggs — are ineffective, Dobson says. This species lays its eggs in hidden places that can be difficult to monitor and tends to develop resistance to common insecticides, he adds. “A new tool like what’s being described in this paper is very much needed,” he says.

But scaling up the technique into an effective public-health strategy for large regions is the challenge, says Gordana Rašić, a molecular ecologist at the QIMR Berghofer Medical Research Institute in Brisbane, Australia.

Rašić says that Wolbachia-based approaches are promising strategies, and she’s hopeful that developing and testing such tools will help to reduce the incidence of mosquito-borne diseases. “We’re living in very exciting times for mosquito control,” she says.

doi: 10.1038/d41586-019-02160-z
See the related News & Views ‘A trial to tackle tiger mosquitoes’.


World’s most invasive mosquito nearly eradicated from two islands in China | Nature

Xiaoying Zheng, Dongjing Zhang, Yongjun Li, Cui Yang, Yu Wu, Xiao Liang, Yongkang Liang, Xiaoling Pan, Linchao Hu, Qiang Sun, Xiaohua Wang, Yingyang Wei, Jian Zhu, Wei Qian, Ziqiang Yan, Andrew G. Parker, Jeremie R. L. Gilles, Kostas Bourtzis, Jérémy Bouyer, Moxun Tang, Bo Zheng, Jianshe Yu, Julian Liu, Jiajia Zhuang, Zhigang Hu, Meichun Zhang, Jun-Tao Gong, Xiao-Yue Hong, Zhoubing Zhang, Lifeng Lin, Qiyong Liu, Zhiyong Hu, Zhongdao Wu, Luke Anthony Baton, Ary A. Hoffmann & Zhiyong Xi. Incompatible and sterile insect techniques combined eliminate mosquitoes. Nature, July 2019. DOI: 10.1038/s41586-019-1407-9​

Mosquito control company gets contracts in Xinjiang, Hunan
By Li Wenfang in Guangzhou | chinadaily.com.cn | Updated: 2019-08-14 14:34

A Guangzhou-based company that runs the world's largest factory of mosquitoes used to control the species signed agreements Tuesday to control mosquitoes in Beitun, Northwest China's Xinjiang Uygur autonomous region, and rice planthoppers in Central China's Hunan province.

Guangzhou Wolbaki Biotech Co will work with the Hunan Academy of Agricultural Sciences in the study of controlling rice planthoppers, which pose a threat to rice crops. Hunan is the largest rice-growing province in the country.

The company also will help Beitun city in Xinjiang's Altay prefecture fight mosquitoes. The Altay region is one of the world's four places with the largest mosquito population, said Xu Longquan, deputy mayor of Beitun.

In spring and summer, when the snow on the Altay Mountains melts, water from reservoirs runs into forests and meadows and forms swarms and pools that become breeding grounds for mosquitoes, Xu said.

Between May and August, which is a local tourism peak season, the number of mosquitoes soars, annoying local residents and tourists, he said.

Although efforts are made every year to control mosquitoes, it is hard to tackle the problem at the root.

Guangzhou Wolbaki chairman Xi Zhiyong, who is also director of the Laboratory of Tropical Disease Control and Prevention at Guangzhou-based Sun Yat-sen University, has led the research on using mosquitoes to eliminate mosquitoes.

In the research, male mosquitoes are infected with Wolbachia, a bacterium that exists widely in many insects, including mosquitoes.

The eggs produced by female mosquitoes that mate with Wolbachia-infected male counterparts are infertile and that helps lead to reduced mosquito numbers.

The article on the study appeared in the academic journal Nature last month.

 

[JSCh]

Removable floodwalls protect Chinese cities
By Zhang Han Source:Global Times Published: 2019/8/14 23:33:40

Before Typhoon Lekima made landfall, removable aluminum alloy floodwalls were installed along a river bank in Yuyao, East China's Zhejiang Province. Photo: Courtesy of Lei Dong

Domestically-made metal floodwalls have helped Chinese cities resist floods caused by super Typhoon Lekima at half the price of foreign products.

The walls have been set up at key places for flood control, including river banks, bridge heads and intersections in Shouguang, East China's Shandong Province since May as the city's latest improvement in flood control, after half a million Shouguang residents suffered and 60,000 were relocated for flooded areas last year, according to a report of the Science and Technology Daily on Wednesday.

As Lekima brought torrential rain and floods which overflowed concrete dykes and submerged bridges in Shouguang over the weekend, the walls kept floodwaters in a hanging river and protected city centers and low-lying places from being submerged.

Lei Dong, the floodwall's developer, told the Global Times on Wednesday that the walls are made of aluminum alloy plates that can hold back large amounts of floodwater.

"They are easy to assemble to a desired height," said Lei, who is also a professor at Hohai University in Nanjing, East China's Jiangsu Province.

Two people can assemble a 100-meter-long, two meter-high floodwall in an hour, while higher walls require a small hoist, Li said.

If it was not for the walls, the city center of Shouguang would have been destroyed by the floods, residents and property would have been threatened, a local resident named Wang Tinglin was quoted as saying by the Science and Technology Daily.

Removable floodwalls were first adopted by Germany in 1984, and are now widely used in countries like France and Austria.

Lei said China is a latecomer due to the wall's high cost and maintenance. But the domestic ones only cost between 3,000 ($427) and 4,000 yuan a square meter, which is roughly half the price of their foreign counterparts.

Besides Shouguang, Yuyao in Zhejiang Province, Changzhou and Wuxi in East China's Jiangsu Province also installed removable floodwalls to defend against Lekima.

While many Chinese cities still use sandbags to hold back floodwaters, which are time- and labor-consuming, more of them are preparing to use such floodwalls, and the market is huge, Lei said.

Lekima, which is estimated to be the strongest since 1961, has claimed 56 lives with 14 still missing in more than ten provinces as of Wednesday, China's National Climate Center announced on its website.

 

[JSCh]

China building world's largest earthquake warning system
By Gong Zhe
2018-12-31 22:55 GMT+8

Earthquake can be destructive. Unfortunately, we don't have a reliable way to predict.

But technologies can still help us under such a desperate situation. For example, sending a message after the earthquake happens, yet before it travels from underground where we live.

China is building the world's largest earthquake alert system and it's possibly the most advanced.

Engineers are setting up more than 15,000 sensors all over the country and wiring them into a web.

When an earthquake happens, the sensors can send electrical pulses to the control center and then ordinary people's smartphones.

The signal travels at (almost) light speed and is much faster than the devastating earthquake shaking, giving local people a little bit time to prepare.

According to an internal document CGTN got from the project managers, the system can send messages to people less than two seconds after the earthquake happens.

So the time between the warning and the actual impact might only be seconds or a minute. But it's proved to be life-saving because every second matter in this situation.

Similar systems can be found in other earthquake-prone places including Japan and U.S. west coast.

But China's system can be more advanced in many ways.

"It will be the largest earthquake observation network in the world," said Li Shanyou, deputy chief engineer of the system.

"It's more integrated than the Japanese and the U.S. ones," he added.

The system can not only detect the movement of the continents but also calculate the possible impact of an earthquake.

So it will automatically warn local people, making it much faster than human observation.

"It can make experts from other countries envy," Li told CGTN.

The system, overseen by China's Ministry of Emergency Management, is set to be completed in 2022.

China, Indonesia cooperate in earthquake early warning system
Source: Xinhua| 2019-08-16 01:37:25|Editor: ZX

Representatives from Indonesia and China sign an agreement at the launching ceremony of a joint construction project of Earthquake Early Warning System (EEWS) in Jakarta, Indonesia, on Aug. 15, 2019. China's Institute of Care-Life (ICL) and Indonesia's Meteorology, Climatology, and Geophysical Agency (BMKG) announced a joint construction project on Thursday to install EEWS in several locations, aiming at completing Indonesia's system which only serves for tsunami warning system at present. (Xinhua/Du Yu)

JAKARTA, Aug. 15 (Xinhua) -- A Chinese researcher and developer institution and an Indonesian agency announced a joint construction project on Thursday to install Earthquake Early Warning System (EEWS) in several locations, aiming at completing Indonesia's system which only serves for tsunami warning system at present.

Under the joint project carried out by China's Institute of Care-Life (ICL) and Indonesia's Meteorology, Climatology, and Geophysical Agency (BMKG), EEWS equipment were installed in Sunda Strait, West Java, Banten and some provinces on Sumatra island, identified as earthquake-prone areas.

Hailing the joint construction of EEWS project in Indonesia, Cultural Chancellor at the Chinese Embassy Zhou Bin said the joint project would deepen the cooperation between China and Indonesia in disaster mitigation.

"I hope Institute of Care-Life of China can closely work together with BMKG to successfully complete the installation of earthquake early warning system, assuring that the system can provide greater benefit in Indonesia's earthquake warning," he addressed the event held in the BMKG premises.

ICL Director Wang Tun said Indonesia sits in world's most active seismic zone called the Circum-Pacific seismic belt.

It is a typical earthquake-prone area. Like China, Indonesia is a country that is deeply plagued by earthquake disasters, he added.

BMKG Chief Dwikorita Karnawati said construction of the EEWS in Indonesia is an urgent projects as threats from earthquakes have been escalating significantly in the last few months.

The EEWS would complete Indonesia's early warning system for tsunami that usually follows an earthquake striking in the sea, she said. Indonesia's tsunami warning system has been in operation since 2008.

"The EEWS is expected to provide warning from 15 to 10 seconds before an earthquake occurs. It will give more golden time for people to safety," she said in her remarks.

The EEWS system would eventually be installed in Indonesia's public transport system, industries, office buildings to avoid secondary accidents that could be generated by the earthquake, Karnawati said.

She added that the existing tsunami early warning system is only capable of identifying earthquake after it takes place and analyze possible tsunami that could be triggered by the earthquake.

 

[JSCh]

China’s Self-Developed Medical Imaging Device PET/CT Enters Final Clinical Trial
DOU SHICONG
DATE: FRI, 05/04/2018 - 14:28 / SOURCE:YICAI

China’s Self-Developed Medical Imaging Device PET/CT Enters Final Clinical Trial

(Yicai Global) May 4 -- The world’s first fully-digital PET/CT has entered the final phase of clinical tests. PET/CT is a new type of medical imaging device that combines positron emission tomography with computed tomography, two diagnosis and treatment technologies.

A team led by Prof. Xie Qingguo of Huazhong University of Science and Technology in Wuhan, china's central Hubei province developed the device.

The First Affiliated Hospital of Sun Yat-sen University and Sun Yat-sen University Cancer Center are soliciting volunteers from the public to clinically test the equipment’s safety and efficacy during imaging diagnosis, Chinese Science News reported yesterday. After 120 cases of clinical trials conclude, registration documents will be submitted to relevant authorities.

The new PET/CT device is fully digital and able to precisely sample. It can detect tumors earlier and more accurately than conventional PET/CT devices. It also finds wide use in early detection of senile dementia and Alzheimer's.

The five-year survival rate of Chinese cancer patients is a mere 31 percent, less than half of that in the US. This low ratio is in part to blame on delayed detection and treatment, and the PET/CT device can significantly improve the capability of early cancer detection through its advantages in imaging performance, noted Zhang Xiangsong, director of nuclear medicine department of the First Affiliated Hospital, Sun Yat-sen University.

Xie’s team started research into fully-digital PET/CT in 2001 and developed the new device in 2016, which solved the technical problem of the inability of traditional PET devices to digitize scintillating pulse signals, and thus it significantly reduces detection time and costs.

China self-developed full-digital PET completes multiple brain imaging
Source: Xinhua| 2019-08-16 16:06:06|Editor: Li Xia

WUHAN, Aug. 16 (Xinhua) -- China's first home-developed full-digital positron emission tomography (PET) scanner has completed multiple clinical cases of brain imaging.

It was recently installed in the First Affiliated Hospital of Sun Yat-Sen University in the southern Chinese city of Guangzhou, Guangdong Province.

Mainly used for early diagnosis and accurate treatment of neurological diseases such as brain tumors and Parkinson's disease, the equipment is believed to be the world's first full-digital PET exclusively developed for cerebral imaging.

It was developed after 19 years of efforts by a team led by Xie Qingguo, a biomedical engineering professor at the Huazhong University of Science and Technology in Wuhan, capital of central China's Hubei Province.

"Multiple clinical trials have provided clear images of brain sulci and gyri and legible pictures of ventricles of the brain," said Zhang Xiangsong, chief physician of the Department of Nuclear Medicine at the hospital.

The brain imaging results reflected an ultra-high biochemical sensitivity of the PET system, which has great potential for exploring brain science and studying brain diseases, he added.

A 30-year-old female patient of the hospital was recently diagnosed with Parkinson's disease by the equipment. "With early detection and proper therapy and medication, she can still expect to live as long as a healthy person," Zhang said.

 

[JSCh]

Physics - Synopsis: Quantum Interference Across an Astronomical Distance
August 21, 2019

Researchers witness quantum interference and entanglement between photons from sources 150 million km apart—the Sun and a quantum dot in their lab.

C.-Y. Lu and L.-C. Peng/HFNL

In 1987, a landmark experiment demonstrated a striking quantum optical effect: When two identical photons simultaneously enter a beam splitter, quantum interference forces both of them to bunch together and always exit from the same beam splitter port. Subsequent variations of the experiment have tested a variety of settings to show that photons from distant sources can show quantum interference. Now, a team of researchers has harnessed sunlight to demonstrate quantum interference between photons generated 150 million km apart, setting the stage for quantum optics experiments on astronomical scales.

These so-called Hong-Ou-Mandel experiments rely on devices that generate single, identical photons on command. The Sun, however, emits photons across a range of frequencies and polarizations and with uncontrollable arrival times. To turn it into a single-photon source, Chao-Yang Lu, at the University of Science and Technology of China, Shanghai, and colleagues hooked up a solar telescope to a series of fibers, filters, and gratings designed to spit out photons that match those generated by a semiconductor quantum dot in their lab. When they combined the two photon streams in a beam splitter, they found that when photons arrived simultaneously, they exited the same port 90% of the time.

This observation indicates interference above and beyond that expected from classical physics—showing that thermal light from a natural source can be used in quantum optical experiments. The team went on to generate entangled states between photons from the two disparate sources and demonstrated that such states clearly violated a Bell inequality, a test that unambiguously reveals nonlocal correlation between particles. The results suggest that sunlight could be used as an independent light source in certain quantum encryption schemes, the team says.

This research is published in Physical Review Letters.

–Christopher Crockett
Christopher Crockett is a freelance writer based in Arlington, Virginia.

Quantum Interference between Light Sources Separated by 150 Million Kilometers
Yu-Hao Deng, Hui Wang, Xing Ding, Z.-C. Duan, Jian Qin, M.-C. Chen, Yu He, Yu-Ming He, Jin-Peng Li, Yu-Huai Li, Li-Chao Peng, E. S. Matekole, Tim Byrnes, C. Schneider, M. Kamp, Da-Wei Wang, Jonathan P. Dowling, Sven Höfling, Chao-Yang Lu, Marlan O. Scully, and Jian-Wei Pan

Phys. Rev. Lett. 123, 080401 (2019)
Published August 21, 2019
​

 

[JSCh]

Viewpoint: A Prediction for “Hot” Superconductivity

• José A. Flores-Livas, Department of Physics, Sapienza University of Rome, Rome, Italy
• Ryotaro Arita, Department of Applied Physics, University of Tokyo, Tokyo, Japan

August 26, 2019• Physics 12, 96

A proposed hydrogen-rich solid would superconduct above the boiling point of water—though the material would need to be subjected to a colossal pressure.



....

Physics - Viewpoint: A Prediction for “Hot” Superconductivity

Route to a Superconducting Phase above Room Temperature in Electron-Doped Hydride Compounds under High Pressure
Ying Sun, Jian Lv, Yu Xie, Hanyu Liu, and Yanming Ma

Phys. Rev. Lett. 123, 097001 (2019)

Published August 26, 2019​

 

[JSCh]

↑↑↑
AUGUST 27, 2019 REPORT
Prediction: Hydride compound should be superconductive at high temperature and pressure
by Bob Yirka , Phys.org

Ma and colleagues predict that, under a pressure of 250 GPa, the compound Li2MgH16 will superconduct with a transition temperature of around 200C. According to their calculations, the lithium atoms (green) help prevent the hydrogen atoms (small red spheres) from forming H2, which would block superconductivity. Credit: Y. Sun et al. DOI: 10.1103/PhysRevLett.123.097001

A team of researchers at Jilin University has calculated that a certain hydride compound should be superconductive at high temperature and under very high pressure. In their paper published in the journal Physical Review Letters, the group describes the work they did that led to their theory.

For over 100 years, scientists have been intrigued by the possibility of using superconductive materials in real-world products. Such materials would solve heat problems with electronic devices and would also make them far more efficient than those available today. Unfortunately, scientists have not been able to find a material that superconducts at room temperature and ambient pressure. Most materials tested thus far become superconductive at extremely low temperatures, limiting their use in a commercial product.

In recent years, researchers have found materials that become superconductive at high temperatures. Most are hydrides, which, as their name suggests, are materials rich in hydrogen—mostly binary compounds. In this new effort, the researchers bucked the trend of finding superconducting hydrides via experimentation in the lab—instead, they have developed a theory that suggests a ternary hydride Li2MgH16 should become superconducting at a temperature of approximately 473 K and pressure of 250 GPa. The researchers note that in their theory, Li2MgH16can actually be considered as a binary hydride (MgH16) that has been doped with lithium to serve as an electron donor. Without the lithium, the hydride would simply break down into H2 when exposed to high pressure.

Notably, the work by the team in China is purely theoretical—they have made no effort to create and test their ideas. This is because the pressure required to make the material transition to superconducting would be difficult to achieve—it is close to that found at the Earth's core. But the work does represent a change in approach to finding a material that superconducts at room temperature and ambient pressure—using theory and math. They suggest their work shows that conventional physics tools such as density-functional theory calculations can be used in the search, speeding up the process and perhaps the eventual discovery of truly usable superconducting materials.


https://phys.org/news/2019-08-hydride-compound-superconductive-high-temperature.html

 

[JSCh]

Study reveals possible mechanism behind human embryo implantation
Source: Xinhua| 2019-08-27 16:41:11|Editor: Li Xia

BEIJING, Aug. 27 (Xinhua) -- Chinese researchers have revealed how the gene regulatory network and epigenetic mechanisms potentially control the human embryo implantation process.

After a sperm fertilizes an egg, they become a totipotent embryo which is capable of differentiating into an unlimited number of specialized cell types. It travels and attaches itself into the wall of the uterus at about the seventh day, which is called implantation. Then, it is possible for the embryo to initiate a successful pregnancy.

Implantation failure is a major cause of early pregnancy loss in humans. Due to the difficulty of obtaining human embryos early after implantation, rodent and monkey embryos were usually used in previous studies, which cannot accurately show regulatory mechanisms of implantation in humans.

In the study published in the journal Nature, researchers from Peking University and Peking University Third Hospital observed and analyzed human peri-implantation embryos in vitro culture system for the embryo development after implantation.

The researchers reconstructed the process of human embryo implantation, generating a map of gene regulatory network and DNA methylation at whole genome-scale.

DNA methylation is a chemical alteration to DNA in mammals that controls how active a gene is within a cell. During peri-implantation development, embryonic cells are directed toward their future lineages, and DNA methylation poses a fundamental epigenetic barrier that guides and restricts differentiation.

The researchers said that a mother-to-offspring connection is prepared to be established during implantation. The first three cell lineages produced by the embryo presented different increasing paces of DNA methylation.

For instance, some hormone-related genes are expressed in trophoblasts, cells forming the outer layer of the cellular mass of the embryo.

The researchers said this study provides insights into the complex molecular mechanisms that regulate the implantation of human embryos in the hope of inspiring the reproductive medicine.

"With the black box of this unique embryonic developmental stage being gradually uncovered, we are about to provide the possibility of early diagnosis and screening of defective embryos before the embryo transplantation," said Tang Fuchou from Peking University, corresponding author of the study.

The researchers terminated the in vitro culture of embryos before day 14 in accordance to the international ethical guideline.

Fan Zhou, Rui Wang, Peng Yuan, Yixin Ren, Yunuo Mao, Rong Li, Ying Lian, Junsheng Li, Lu Wen, Liying Yan, Jie Qiao, Fuchou Tang. Reconstituting the transcriptome and DNA methylome landscapes of human implantation. Nature (2019). DOI: 10.1038/s41586-019-1500-0​

 

[JSCh]

China develops superconducting hybrid power line that could span the country | South China Morning Post

• Prototype tested last month transports high-voltage power and liquefied natural gas side by side
• It could cut the high cost and waste involved in sending energy from the far west to the east coast

Stephen Chen
Published: 5:45am, 29 Aug, 2019
Updated: 9:45am, 29 Aug, 2019

The 10-metre prototype line, combining high-voltage electricity and liquefied natural gas. Photo: Chinese Academy of Sciences

Chinese scientists have developed the world’s first prototype of a superconducting hybrid power line, paving the way for construction of a 2,000km (1,243-mile) line from energy-rich Xinjiang in the country’s far west to its eastern provinces.

The 10-metre, proof-of-concept wire and liquid natural gas hybrid transmission line was up and running at the Chinese Academy of Sciences’ Institute of Electrical Engineering in Beijing last month to show the feasibility of the technology.

The line contains a superconducting wire which can transmit nearly 1,000 amps of electric current at more than 18,000 volts with zero resistance.

In a further difference from a traditional power line, the gap between the superconducting wire and the power line’s outer shell is filled by a flow of slowly moving natural gas liquefied at low temperatures – between minus 183 and minus 173 degrees Celsius (minus 279 to minus 297 Fahrenheit). This allows the line to transfer electricity and fossil fuel at the same time.

Professor Zhang Guomin, the government research project’s lead scientist, told the South China Morning Post that the voltage and current could be much higher in its real-world applications.

“This technology can take the overall efficiency of long-distance energy transport to new heights,” he said.

Existing infrastructure to transfer energy from Xinjiang Uygur autonomous region to the developed eastern areas such as Shanghai has high operational costs because almost 10 per cent of the energy is lost in transmission, according to some studies.

That infrastructure includes the world’s most advanced high-voltage power line and four natural gas pipes, each thousands of kilometres long. One of the natural gas pipelines, from Xinjiang to Shanghai, cost 300 billion yuan (US$42 billion).

The superconductor and natural gas hybrid line offered a possible solution, Zhang said. Loss of electricity over the superconducting wire would be almost zero because of the elimination of resistance to the movement of electrons, he said.

The transport of liquefied natural gas would also be efficient, because one cubic metre (1,000 litres) of it would be equivalent to 600 cubic metres of the same fuel in gas form.

The temperature needed for liquefaction of natural gas is almost identical to that required for occurrence of superconductivity, at about minus 163 degrees.

Wang Gengchao, professor of physics at East China University of Science and Technology in Shanghai, said the combination was a “smart idea”.

Superconducting materials are not new but their applications have been limited by the difficulty and cost of creating and maintaining the low-temperature environment.

“They are trying to kill two birds with one stone,” Wang, who was not involved in the study, said.

“But whether the technology can find a use in large-scale infrastructure depends on other things, such as safety. Not everyone will feel comfortable with the idea of putting a high-voltage electric line and flammable natural gas side by side.”

Zhang said another new prototype line, about 30 metres long, was being developed and the 2,000km project was awaiting government approval.

He said the team had solved some major technical obstacles, including reducing the risk of accidents from electrical sparks and gas leakage.

“Many problems remain to be solved, but we are confident this technology will work,” he said. “It will protect the environment. It will save a lot of land from being used for power and gas lines.”

Xinjiang has more energy resources than any other Chinese province or region. It has nearly half of the nation’s coal reserves, a third of its oil and gas, and some of the largest wind and solar farms, according to government statistics.

 

[JSCh]

This protein is how creatures sense cold, researchers discover—and it’s found in organisms ranging from tiny worms to humans | University of Michigan News
August 29, 2019
Emily Kagey ekagey@umich.edu

​

ANN ARBOR—Researchers have identified a receptor protein that can detect when winter is coming.

The findings, published Aug. 29 in the journal Cell, reveal the first known cold-sensing protein to respond to extreme cold.

“Clearly, nerves in the skin can sense cold. But no one has been able to pinpoint exactly how they sense it,” said Shawn Xu, a faculty member at the University of Michigan Life Sciences Institute and senior author of the study. “Now, I think we have an answer.”

When environmental temperatures drop to uncomfortable, and even dangerous levels, receptor proteins within the sensory nerves in the skin perceive the change, and they relay that information to the brain. This is true for organisms from humans all the way down to the tiny, millimeter-long worms that researchers study in Xu’s lab at the Life Sciences Institute: the model system Caenorhabditis elegans.

Shawn Xu​

“When you step outside and you sense it’s too cold, you’re going to take action to get back to a warmer environment as soon as you can,” said Xu, who is also a professor in the U-M Medical School’s Department of Molecular and Integrative Physiology. “When the worms sense cold, they also engage in avoidance behavior—moving away from cold temperatures, just like humans.”

But unlike humans or other complex organisms, C. elegans have a simple, well-mapped genome and a short lifespan, making them a valuable model system for studying sensory responses.

Previous searches for a cold receptor have been unsuccessful because researchers were focusing on specific groups of genes that are related to sensation, which is a biased approach, Xu said. Capitalizing on the simplicity of C. elegans, he and his colleagues instead took an unbiased approach. They looked across thousands of random genetic variations to determine which affected the worms’ responses to cold.

The researchers found that worms missing the glutamate receptor gene glr-3 no longer responded when temperatures dipped below 18 degrees Celsius (64 F). This gene is responsible for making the GLR-3 receptor protein. Without this protein, the worms became insensitive to cold temperatures, indicating that the protein is required for the worms to sense cold.

What’s more, the glr-3 gene is evolutionarily conserved across species, including humans. And it turns out the vertebrate versions of the gene can also function as a cold-sensing receptor.

“It’s really exciting. This was one of the few remaining sensory receptors that had not yet been identified in nature.”
Shawn Xu

When the researchers added the mammalian version of the gene to mutant worms lacking glr-3—and were thus insensitive to cold—they found that it rescued the worms’ cold sensitivity. They also added the worm, zebrafish, mouse and human versions of the genes to cold-insensitive mammalian cells. With all versions of the gene, the cells became sensitive to cold temperatures.

The mouse version of the gene, GluK2 (for glutamate ionotropic receptor kainate type subunit 2), is well known for its role in transmitting chemical signals within the brain. The researchers discovered, however, that this gene is also active in a group of mouse sensory neurons that detect environmental stimuli, such as temperature, through sensory endings in the animals’ skin.

Reducing the expression of GluK2 in mouse sensory neurons suppressed their ability to sense cold, but not cool, temperatures. The findings provide additional evidence that the GluK2 protein serves as a cold receptor in mammals.

“For all these years, attention has been focused on this gene’s function in the brain. Now, we’ve found that it has a role in the peripheral sensory system, as well,” Xu said. “It’s really exciting. This was one of the few remaining sensory receptors that had not yet been identified in nature.”

In addition to Xu, study authors are: Elizabeth Ronan, Wei Cai, Mahar Fatima, Hankyu Lee, Zhaoyu Li, Kevin Pipe and Bo Duan of U-M; Jianke Gong, Jinzhi Liu, Feiteng He and Wenyuan Zhang of Huazhong University of Science and Technology in China and U-M; Jianfeng Liu of Huazhong University of Science and Technology; and Gun-Ho Kim of the Ulsan National Institute of Science and Technology in South Korea.

More information:

• Study: A Cold-Sensing Receptor Encoded by a Glutamate Receptor Gene
• X.Z. Shawn Xu Lab

 

[JSCh]

A novel way to repair tooth enamel | Zhejiang University
2019-09-03 Global Communications

Professor TANG Ruikang with the Zhejiang University Department of Chemistry will experience “tooth growth”. The research team led by him developed a biomimetic regenerative solution which could be applied to the tooth cavity and establish a biomimetic crystalline-amorphous mineralization frontier to induce the growth of enamel with a precise maintenance of the original structural complexity within 48 hours.

This study is published online in an article entitled “Repair of tooth enamel by a biomimetic mineralization frontier ensuring epitaxial growth” in the journal of Science Advances. To the best of my knowledge, this has been the best tooth enamel regenerative substance so far and it has the potential to repair tooth enamel clinically in a real sense, observed Helmut Cölfen, a German professor of physical chemistry with the University of Konstanz.

Enamel is the hardest tissue in the human body and contains the highest percentage of minerals (at 96%). This translucent substance is approximately 2 millimeters thick. “Enamel resembles a layer of natural inorganic crystalline mineral and is primarily composed of nonstoichiometric fluoridated carbonate apatite crystals that are tightly packed with well-defined orientations to ensure striking hardness,” said Dr. SHAO Changyu, the lead author of the study.

As a highly mineralized biological tissue, enamel is perceived as a purely inorganic substance and cannot self-repair for lack of a bioorganic matrix including cells. Despite being the hardest tissue in the body, enamel becomes susceptible to degradation, especially by acids from food and drink. Once enamel is damaged, people will have cavities in teeth, which will lead to nightmarish pain.

Enamel remineralization is currently deemed as the most formidable challenge in the field of bionics. Previous endeavors to regrow enamel by using a range of materials such as composite resins, ceramics and amalgam failed to achieve permanent repair because of the imperfect compatibility between these foreign materials and the native enamel.

“Optimally, scientists should achieve the unity of material, structure and mechanics and repair enamel in situ,” said Dr. LIU Zhaoming, a co-author of the study.

TANG et al. proposed a novel approach to tooth enamel regrowth. They found that mixing calcium and phosphate ions—two minerals which are found in enamel—with the chemical trimethylamine in an alcohol solution causes enamel to grow with the same structure as teeth.

Digital image of a whole tooth, in which the left area was covered with acid-resistant varnish (displayed as dark) and the right area was repaired with CPICs containing calcein (displayed as yellow).

When the mixture was applied to human teeth, it repaired the enamel layer to around 2.5 micrometres of thickness. It also achieved the same structure of natural enamel within 48 hours.

“The materials we used in experiments were identical to the human tissue, thereby achieving complete structural regrowth,” LIU said in an assertive way.

The discovery has not yet been proven to work in the “hostile environment” of the mouth, but experts say regrown tooth enamel may be tested in people in the near future. Coincidentally, there is a hidden crack on one of TANG’s teeth. His dentist told him that nothing could be done to repair the tooth because of a too-thin crevice. “After this scientific breakthrough, I am bold enough to be a “guinea pig” for a trial,” said TANG.

“Although we have achieved a precise duplication of the hierarchical and complicated structure in natural enamel, there are a wide spectrum of dental cavities. We need to develop our regenerative model for different circumstances so as to ensure controllability and effectiveness,” said SHAO.

This biomimetic tactic for enamel regeneration can be extended as a general strategy for the construction of structurally complex materials by establishing a biomimetic mineralization frontier for continuous and epitaxial construction, in which the ion clusters act as basic building blocks. This achievement will not only deepen the understanding of biomineralization but also provide a new pathway for bioinspired design and production.

 

[JSCh]

Nature Photonics
Kai Wang, Qian Xu, Shining Zhu, Xiao-song Ma
National Laboratory of Solid-State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures of Nanjing University​

Wave and particle states of light in controllable quantum superposition | SciGlow

Light can behave both as a particle and as a wave. Researchers at Nanjing University have now created controllable quantum superpositions of these two complementary states. In doing so, they extended the experimental capabilities of quantum optics and possibly of future quantum technologies.

15 hours ago

The question whether light consists of particles or instead propagates as a wave through a medium has been the subject of scientific debate throughout most of the history of science. In the 20th century it finally has been established that light can be indeed both, particle and wave, but not at the same time. Still, the nature of light keeps challenging both our understanding and intuition. A case in point are results that researchers from the National Laboratory of Solid-State Microstructures, the School of Physics and the Collaborative Innovation Center of Advanced Microstructures of Nanjing University (China) report today online in the journal Nature Photonics.

In an experiment that involved optical equipment in two laboratories that are 141 metres apart from each other, the team led by Dr. Xiao-Song Ma demonstrated conclusively that light can not only be in wave or particle states, but also in a quantum superposition of the two. Moreover, they showed that the properties of this quantum wave–particle superposition can be tuned, opening up the prospect of ultimately exploiting the new experimental capability in quantum technologies.

Artistic impression of an experiment that achieved genuine quantum wave–particle superposition in a delayed-choice experiment. A pair of entangled photons (blue spheres) enable the non-local quantum control of the output beam splitter of an interferometer (top). The interference pattern on the bottom shows quantum superposition of the wave and particle states of single photons (red spheres). This work realizes quantum control of single-photon quantum states by entanglement and implements a full quantum delayed-choice experiment under strict Einstein locality conditions. Provided by Xiao-Song Ma

Light surprises
The debate on the nature of light has kept many great scientists busy over the centuries. Euclid and Ptolemy have made contributions, as did Descartes, Newton, and many other protagonists of the history of science. To explain how shadows form, for instance, light is best considered to consist of particles. By contrast, interference effects—most notably in the double-slit experiments of Thomas Young at the beginning of the 19th century—bring the wave nature of light to full display. The advent of quantum physics in the 20th century finally provided a framework to understand particles and waves as dual states of light.

But even a century on, surprising phenomena emerge from the wave–particle duality. A famed example is the delayed-choice thought experiment, originally proposed by John Archibald Wheeler and further developed by other physicists. In that thought experiment, an external observer can choose (by changing one component of the experiment) whether single quanta of light, so-called photons, behave as particles or as waves. Intriguingly, the choice between particle and wave states can be delayed to until after the photon enters the experimental setup.

“The experiment dramatically underscores the different conceptions of space and time in classical and quantum physics, which is one of the most intriguing effects in quantum mechanics”, says Ma.

Thought-provoking experiments
In recent years, Wheeler’s thought experiment and variants of it have been implemented in practice. And there is more to come. Ma: “Thanks to the rapid development of optical technology, it has not only become possible to realize such thought experiments, but also to design new ones.” And designing a new experiment is what Ma and his team did. Building on earlier work, they developed a quantum version of the delayed-choice experiment, where wave and particle states of single photons are placed in coherent superposition.

The key to achieve such a mixture of particle and wave states is to use quantum states of additional photons to control the component that allows switching between wave and particle. But that ‘quantum-controlled choice’ can only be considered truly independent if the control unit is placed so far away from the main experiment that it could not possibly interfere with the rest of the experiment. Physicists speak of ‘Einstein locality conditions’ being ensured.

Particle–wave duality on the next level
The experiment of the Nanjing group is the first quantum delayed-choice experiment under strict Einstein locality conditions. Achieving that required connecting equipment located in two separate labs, 141 metres away from one another.

“By carefully arranging the location and timing of the experimental setup, we achieved the required relativistic separations between relevant events,” says Kai Wang, a PhD student in Ma’s group and first author of the Nature Photonics paper.

With this experiment the team directly and unambiguously established the quantum nature of superpositions between wave and particle states of light, and also showed how key properties of that superposition can be tuned. Their demonstration therefore is of fundamental importance to quantum optics and at the same time paves the way for realizing non-local control of quantum systems in the context of future quantum technologies.