China Science & Technology Forum

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Physics - Synopsis: Face Recognition with Ghost Imaging
March 26, 2019
Using a variation of a technique known as ghost imaging, researchers demonstrate a face recognition protocol that works without complex image analysis algorithms.

X. Qiu et al., Phys Rev. Lett. (2019)

Face recognition systems typically analyze a person’s photo to select out prominent facial features that are then searched for in a database of previously analyzed photos. But what if you could skip the analysis and use light to directly determine a match? That’s the idea proposed by Lixiang Chen and colleagues from Xiamen University in China, who have demonstrated a simple face recognition system based on ghost imaging. Their method finds matches by searching for correlations between two light beams imprinted with image information.

Ghost imaging uses correlations between photons to image objects with a minimal amount of illumination. The most common method involves shining a light beam into a special crystal that generates a stream of entangled pairs of photons. One photon in each pair travels towards the object, while the other photon (acting as a reference) takes an empty path. Both routes end with detectors, whose outputs are combined to produce an image of the object.

For face recognition, Chen’s team designed and tested an alternate setup that instead imprints the image of a face in the initial light beam. When this “structured” light reaches the crystal, it shares its information between the entangled photons. A spatial light modulator placed in one path acts like a mask that can be programmed with a series of test images. In a demonstration, the researchers used five face photos as their test pool and found a strong correlation peak in the combined detector signals when the selected test image was the same as the initial face image. The team says that their method could be used in low light situations, such as in a “covert operation” that must avoid detection by the target person.

This research is published in Physical Review Letters.

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

Structured-Pump-Enabled Quantum Pattern Recognition
Xiaodong Qiu, Dongkai Zhang, Wuhong Zhang, and Lixiang Chen
Phys. Rev. Lett. 122, 123901 (2019)

Published March 26, 2019​

 

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PUBLIC RELEASE: 26-MAR-2019
Rice cultivation: Balance of phosphorus and nitrogen determines growth and yield
UNIVERSITY OF COLOGNE

In the future, a newly discovered mechanism in control of plant nutrition could help to achieve higher harvests in a sustainable way. Scientists from the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing (China) discovered this mechanism in their research on Asian rice in collaboration with Professor Dr Stanislav Kopriva from the University of Cologne's Botanical Institute and the Cluster of Excellence CEPLAS. The balance between nitrogen (N) and phosphorus (P) is decisive for crop yield. Both nutrients, which the plant absorbs from the soil through its roots, interact more strongly with each other than previously known. The study 'Nitrate-NRT1.1B-SPX4 cascade integrates nitrogen and phosphorus signalling networks in plants' has now appeared in the journal Nature Plants.

Kopriva said: 'For healthy and optimal growth, all living beings need a good balance of minerals. However, we know very little about how plants achieve this balance.' His colleagues in Beijing had observed that the addition of phosphate only had a positive effect on plant growth and yield if a sufficient amount of nitrogen was also available in the soil. 'Together, we have now discovered the mechanism by which nitrogen controls the absorption of phosphate', Kopriva remarked.

A detailed analysis at the molecular level revealed an entire signalling chain that the plant sets in motion - from the sensor that recognizes nitrate quantities to factors that enable the synthesis of the so-called transporters that carry the phosphate into the plant. Kopriva explained: 'Although most of the components were already known individually, it was only through this work that they were brought together into a signalling pathway. This gives us a completely new understanding of how to control plant nutrition. In addition, it enables specific manipulations to either couple the uptake of both nutrients more closely or to separate them from each other - depending on how nutrient-rich the soil on which the rice grows is.'

Professor Dr Stanislav Kopriva from the Botanical Institute of the University of Cologne is co-speaker of the Cluster of Excellence on Plant Sciences CEPLAS at the Universities of Düsseldorf and Cologne, which is funded by the Excellence Strategy of the German Federal Government and the Laender. CEPLAS wants to develop basic knowledge about 'SMART Plants for Tomorrow's Needs'.


Rice cultivation: Balance of phosphorus and nitrogen determines growth and yield | EurekAlert! Science News

Bin Hu, Zhimin Jiang, Wei Wang, Yahong Qiu, Zhihua Zhang, Yongqiang Liu, Aifu Li, Xiaokai Gao, Linchuan Liu, Yangwen Qian, Xiahe Huang, Feifei Yu, Sai Kang, Yiqin Wang, Junpeng Xie, Shouyun Cao, Lianhe Zhang, Yingchun Wang, Qi Xie, Stanislav Kopriva & Chengcai Chu. Nitrate–NRT1.1B–SPX4 cascade integrates nitrogen and phosphorus signalling networks in plants. Nature Plant (2019). DOI: 10.1038/s41477-019-0384-1​

 

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Exotic particles containing five quarks discovered at the Large Hadron Collider
March 27, 2019 12.48pm GMT
Author

1. Harry Cliff
   Particle physicist, University of Cambridge
   

Interviewed

1. 
   Liming Zhang
   Associate Professor, Tsinghua University
   
   
2. 
   Tomasz Skwarnicki
   Professor, Syracuse University
   

Disclosure statement
Harry Cliff is a member of the LHCb Collaboration, though he was not directly involved in the work described in this article.

Partners


University of Cambridge provides funding as a member of The Conversation UK.

Illustration of the possible layout of the quarks in a pentaquark particle. Daniel Dominguez/CERN

Everything you see around you is made up of elementary particles called quarks and leptons, which can combine to form bigger particles such as protons or atoms. But that doesn’t make them boring – these subatomic particles can also combine in exotic ways we’ve never spotted. Now CERN’s LHCb collaboration has announced the discovery of a clutch of new particles dubbed “pentaquarks”. The results can help unveil many mysteries of the theory of quarks, a key part of the standard model of particle physics.

Quarks were first proposed to explain the untidy slew of new particles discovered in cosmic ray and collider experiments in the mid 20th century. This growing “zoo” of apparently fundamental particles caused consternation among physicists, who have a natural bias towards simplicity and order – and hate having to remember more than a few basic principles. The famous Italian physicist Enrico Fermicaptured the mood of his colleagues when he said “Young man, if I could remember the names of all these particles, I would have been a botanist”.

Fortunately, in the 1960s, the American physicist Murray Gell-Mann noticed patterns in the particle zoo, similar to those spotted by Dimitri Mendeleev when he drew up the periodic table of the chemical elements. Just as the periodic table implied the existence of things smaller than atoms, Gell-Mann’s theory suggested the existence of a new class of fundamental particles. Particle physicists were eventually able to explain the hundreds of particles in the zoo as being made up of a much smaller number of truly fundamental particles called quarks.

Mystery hadrons
There are six types of quarks in the standard model – down, up, strange, charm, bottom and top. These also have “antimatter” companions – it is believed that every particle has an antimatter version that is virtually identical to itself, but with the opposite charge. Quarks and antiquarks get bound together to make particles known as hadrons.

According to Gell-Mann’s model, there are two broad classes of hadrons. One is particles made of three quarks called baryons (which include the protons and neutrons that make up the atomic nucleus) and the other particles made of a quark and an antiquark known as mesons.

Until recently, baryons and mesons were the only types of hadrons that had been seen in experiments. However, back in the 1960s, Gell-Mann also raised the possibility of more exotic combinations of quarks, such as tetraquarks (two quarks and two antiquarks) and pentaquarks (four quarks and one antiquark).

In 2014, LHCb, which runs one of the four giant experiments at CERN’s Large Hadron Collider, published a result showing that the snappily named Z(4430)+ particle was a tetraquark. This started a flurry of interest in new exotic hadrons. Then, in 2015, LHCb announced the discovery of the first ever pentaquark, adding a brand new class of particle to the hadron family.

The results presented by LHCb today expand upon that first pentaquark discovery by finding additional such particles. This was possible thanks to a big chunk of new data recorded during the second run of the Large Hadron Collider. Liming Zhang, an associate professor at Tsinghua University in Beijing and one of the physicists who made the measurement, said that “we now have ten times more data than in 2015, which allows us to see more exciting and finer structures than we could before.” When Liming and his colleagues examined the original pentaquark discovered in 2015, they were surprised to find that it had split in two. The original pentaquark was actually two separate pentaquark particles that had such similar masses that they originally looked like a single particle.

LHCb. Maximilien Brice et al./CERN

As if two pentaquarks for the price of one wasn’t exciting enough, LHCb also found a third pentaquark with a slightly smaller mass than the other two. All three pentaquarks are made of one down quark, two up quarks, a charm quark and a charm antiquark.

The big question now is: what is the precise internal structure of these pentaquarks? One option is that they are truly made of five quarks, with all of them mixed together evenly within a single hadron. Another possibility is that the pentaquarks are really a baryon and a meson stuck together to form a loosely bound molecule, similar to the way that protons and neutrons bind together inside the atomic nucleus.

Tomasz Skwarnicki, a professor of physics at Syracuse University in New York who also worked on the measurement, told me that the new companion state “is at a mass which offers hints about internal structure of pentaquarks”. The most likely option is that these pentaquarks are baryon-meson molecules, he added. To be absolutely sure, physicists will need more experimental data, as well as further studies from theorists, meaning that the story of these pentaquarks is far from over.

These results complete a week of exciting new announcements from LHCb, which included the discovery of a new kind of matter-antimatter asymmetry. The LHC has yet to discover any particles beyond the standard model that could help to explain mysteries like dark matter, an invisible but unknown substance that makes up the majority of matter in the universe.

But these exciting measurements show that there is still lots to learn about the particles and forces of the standard model. It may be that our best chance of finding answers to the big questions facing fundamental physics in the 21st century lies in more detailed studies of the particles we already know about rather than discovering new ones. Either way, we still have a great deal to discover.


https://theconversation.com/exotic-...iscovered-at-the-large-hadron-collider-114211

 

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PUBLIC RELEASE: 27-MAR-2019
Pressure makes best cooling
CHINESE ACADEMY OF SCIENCES HEADQUARTERS

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Figure 1. Schematic diagram of the refrigeration cycle based on barocaloric effects. CREDIT: HUANG Chengyu

Phase transitions take place as heat (i.e., entropy) is exchanged between materials and the environment. When such processes are driven by pressure, the induced cooling effect is called the barocaloric effect, which is a promising alternative to the conventional vapor compression cycle.

For the purposes of real application, it is desirable for a material to have larger entropy changes induced by smaller pressure.

Recently, an international research team led by Prof. LI Bing from the Institute of Metal Research of the Chinese Academy of Sciences has found that a class of disordered materials, called plastic crystals, exhibits record-large barocaloric effects under very weak pressure.

The typical entropy changes are about several hundred joules per kilogram per kelvin, which is 10 times better than previous materials.

Utilizing large-scale facilities in Japan and Australia, the team revealed that the constituent molecules of these materials are extensively orientationally disordered on the lattices and these materials are intrinsically very deformable.

As a result, a tiny amount of pressure is able to suppress the extensive orientational disorder. As a result, pressure-induced entropy changes are obtained. These two merits make plastic crystals the best barocaloric material so far.

This research is the first report that entropy changes can exceed 100 joules per kilogram per kelvin. It represents the best results among all caloric-effect materials (barocaloric effect as well as its analogous effects such as the magnetocaloric, electrocaloric and elastocaloric effects), and is regarded as a milestone.

The microscopic physical scenario established using the neutron scattering technique is helpful for designing even better materials in the future.

As far as refrigeration application is concerned, the plastic crystals reported here are very promising given that they are abundantly available, environmentally friendly, easily driven and high-performance.

This work points to a new direction for emerging solid-state refrigeration technologies.


Pressure makes best cooling | EurekAlert! Science News

Bing Li, Yukinobu Kawakita, Seiko Ohira-Kawamura, Takeshi Sugahara, Hui Wang, Jingfan Wang, Yanna Chen, Saori I. Kawaguchi, Shogo Kawaguchi, Koji Ohara, Kuo Li, Dehong Yu, Richard Mole, Takanori Hattori, Tatsuya Kikuchi, Shin-ichiro Yano, Zhao Zhang, Zhe Zhang, Weijun Ren, Shangchao Lin, Osami Sakata, Kenji Nakajima & Zhidong Zhang. Colossal barocaloric effects in plastic crystals. Nature (2019). DOI: 10.1038/s41586-019-1042-5​

 

[JSCh]

Chinese scientists develop new material for super batteries
Source: Xinhua| 2019-03-28 19:02:53|Editor: ZX

TIANJIN, March 28 (Xinhua) -- Researchers from Tianjin University said Thursday that they had developed ultra-high-energy fluorinated carbon materials, the key technology to realizing ultra-energy storage.

Fluorinated carbon is a solid-state cathode material with the highest theoretical energy density in the world. It has broad application prospects in the fields of electronic devices, biomedicine and equipment power supply.

Feng Wei said his team, by altering covalent fluorocarbon structures, developed the new fluorinated carbon material with both high energy density and high power density, or long battery duration and large energy discharge, a property lacking in existing fluorinated carbon materials.

The research results show that the energy density of the new material is 2,738 Wh/kg, which is 30 percent higher than that of similar products, and can work stably under the condition of a large discharge current.

"Using the new material, the ultra-long-endurance for unmanned aerial vehicles, cardiac pacemakers with lifelong power, and bionic robotic fish traveling tens of thousands of kilometers in the ocean may be seen in the future," Feng said.

Feng said his team has realized the stable production of the new material, and has delved into its fluorination mechanisms, structural regulation and electrochemical kinetics.

 

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How to Free Trapped Radicals from Carboxyl
Mar 29, 2019

USTC young scientists develop a cheap and simple visible light catalytic system

The removal of carboxyl groups and the release of alkyl radical fragments from the tight binding of carboxyl groups are promising directions in organic synthesis, especially in drug synthesis. Various catalysts have been designed to solve this challenge.

In a recent study published in Science, scientists from University of Science and Technology of China (USTC) of Chinese Academy of Sciences reported their newly developed catalyst system which is cheap and simple.

The free radical is versatile and controllable, representing a "Great Holy" in organic synthesis, but it is pressed by the "big mountain" of the carboxyl group.

Figure: Free radical, the Monkey King is bound by the "big mountain" of the carboxyl group. The mainstream photocatalytic systems are complex and costly. The novel catalyst uses a new mechanism to combine the cheap catalyst with the carboxyl group, pushes the redox reaction cycle, and easily sets free the "free radicals". (Image by CUI Jie)

Conventional decarboxylation processes have limitations in industrialization. In recent years, the scientific community has tried to use photocatalytic reaction to achieve decarboxylation conversion, which has adavantages such as simple operation, easy control, and energy saving. The photocatalytic system has been successfully applied to the synthesis of various complex functional molecules.

However, most photoredox catalysts in current use are composed of precious metal complexes such as iridium and ruthenium or are synthetically elaborate organic dyes with complicated structures. It is important to develop environmental friendly and multifunctional photocatalytic systems. The new catalyst has a new way to use the new mechanism to combine cheap catalyst with carboxyl group, push redox reaction cycle, and easily and freely rescue the "free radicals".

Based on visible light excitation for intermolecular charge transfer, scientists from USTC proposed a new concept to construct a catalytic redox cycle for organic synthesis. They discovered a simple, easily available, highly efficient and non-metallic anionic composite photocatalytic system for decarboxylative reaction of carboxylic acid derivative.

The proposed catalytic system simultaneously drives a redox cycle, simplifies the photocatalytic system, and reduces the cost of the photocatalyst. The system breaks the limitations of traditional heating method, and solves the problems of transition metals remaining in the synthesis of functional compounds and drugs.

Using this system, redox-active esters derived from various natural and unnatural amino acids successfully trigger decarboxylativr coupling reactions with high efficiency and gram scale production, indicating the feasibility of industrialization.

It is also expected to promote the scale industrialization of photocatalytic technology in the production of important functional molecules, with important synthetic chemical value and good industrial application prospects.

The results may initiate a new area of research in photoredox catalysis by introducing a tricomponent system based on a salt, a phosphine and an electron- acceptor to access redox active complexes without the need for traditional transition metal or complex dye catalysts.

This study illustrated that decarboxylative alkylation is accomplished without precious transition metals or organic dyes, which may be good news for many synthetic chemists.


How to Free Trapped Radicals from Carboxyl---Chinese Academy of Sciences

Ming-Chen Fu, Rui Shang, Bin Zhao, Bing Wang, Yao Fu. Photocatalytic decarboxylative alkylations mediated by triphenylphosphine and sodium iodide. Science (2019). DOI: 10.1126/science.aav3200​

 

[JSCh]

PROJECTS AND FACILITIES | NEWS
Physicists in China unveil plans for underground gravitational-wave observatory
01 Apr 2019

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Tunnel vision: The Kamioka Gravitational Wave Detector in Japan (pictured), which will begin full operation later this year, is currently the world's only underground gravitational-wave detector (Courtesy: Michael Banks)

Physicists in China have revealed plans to build a massive new underground facility in the centre of the country to study gravitational waves and test Einstein’s theory of general relativity to an unprecedented precision. The Zhaoshan Long-baseline Atom Interferometer Gravitation Antenna (ZAIGA), is to be located in eastern Wuhan and cost two billion yuan (about £226m). If the project is fully funded, it could be operational by 2025.

The first phase of ZAIGA, which could be complete by the end of 2020, will involve building a 300 m vertical tunnel under the Zhaoshan Mountain – 80 km southeast of Wuhan — to study various predictions resulting from general relativity. It costs 600 million yuan (£68m) and is fully funded by local governments and the Chinese Academy of Sciences. “We have just completed site exploration with tunnel excavation starting this year,” says Mingsheng Zhan, principal investigator of ZAIGA, who is based at the Wuhan Institute of Physics and Mathematics at the Chinese Academy of Sciences.

The tunnel will be mainly used to test the weak equivalence principle, which implies that the trajectory of a free-fall object is independent of its mass and internal structure. Numerous experiments have proved the principle to be correct, including a 12 m-tall “atomic fountain” – in which a cloud of atoms are tossed upwards in the Earth’s gravitational field by lasers — in Zhan’s lab in Wuhan. The atomic fountains at ZAIGA will be mounted on the top and bottom of the tunnel with a high-vacuum chamber running along it. “The idea of an atomic fountain is to let go of two slightly different atoms and compare how they fall,” says Zhan.

We hope [the experiments] will bring good surprises
Mingsheng Zhan​

Another experiment planned for the tunnel will involve installing optical clocks at both ends to measure the time difference predicted by general relativity: time goes by faster at higher elevation than at a lower elevation due to what is known as gravitational redshift. Zhan says that while atomic clocks aboard Galileo satellites have been a huge success in testing this effect, ground-based optical clocks can be controlled better and are less influenced by outside temperatures.

ZAIGA will also measure the “space-time dragging effect” caused by Earth’s rotation distorting spacetime. This will be done to a higher precision than that carried out by NASA’s Gravity Probe B satellite, which launched in 2004 and ended operations in 2010. “We hope [the experiments] will bring good surprises,” adds Zhan.

China is not, however, alone in such endeavours and some of those tests will also be carried out at a similar facility called the Matter-wave laser Interferometric Gravitation Antenna (MIGA) being built in Rustrel, France, by a consortium of 17 European countries. MIGA features a 300 m-long optical cavity and will carry out precision measurements of gravity as well as applications in geosciences and fundamental physics.

Bouncing atoms

Once the 300 m vertical tunnel is complete, physicists then hope to construct a gravitational-wave observatory, which would be under the mountain at an average depth of 200 m to reduce the effect of seismic noise. Rather than detecting gravitational waves by bouncing laser beams off mirrors as used by the LIGO gravitational-wave observatories in the US, ZAIGA-GW would instead use an atom interferometer. This would involve splitting an atom beam in half, and allowing both halves to travel for a certain distance before being recombined to look for differences in their paths. A slightly longer path would result from a tiny curvature in space-time that could be caused by a passing gravitational wave. Atom interferometers tend to be more sensitive than their laser counterparts as atomic beams travel more slowly, which therefore amplifies any signal from a passing gravitational wave.

Costing 1.5 billion yuan, of which the team have partial funding, ZAIGA-GW would consist of three 1 km-long tunnels in the shape of an equilateral triangle with each arm being an independent atom interferometer. ZAIGA-GW would then aim to detect gravitational waves in the 0.1-10 Hz frequency range, which would be most likely emitted by medium-size black-hole binaries. These black holes have masses between 100 and one million solar masses and are elusive but crucial to explain whether supermassive black holes formed from the expansion of small black holes, from the merger of multiple smaller black holes, or possibly from other scenarios.

Zhan says ZAIGA-GW will be open to international collaboration and the team currently have exchanges with Europe, US as well as Japan, which is building KAGRA — the world’s first underground gravitational-wave observatory to use cryogenic mirrors. Zhan also says that ZAIGA-GW could be later upgraded to 3 km- or 10 km-long arms, “if funding is available”.



Physicists in China unveil plans for underground gravitational-wave observatory – Physics World

 

[JSCh]

Science 12:16, 03-Apr-2019
Transgenic monkeys carrying human gene show human-like brain development
CGTN

Researchers from China and the United States created transgenic monkeys carrying a human gene that is important for brain development, and later observed human-like brain development in the monkeys.

Scientists have identified several genes that are linked to primate brain size. MCPH1 is a gene that is seen during fetal brain development. Mutations in MCPH1 can lead to microcephaly, a developmental disorder characterized by a small brain.

In the study published in the Beijing-based National Science Review, researchers from the Kunming Institute of Zoology, Chinese Academy of Sciences (CAS), the University of North Carolina in the United States and other research institutions reported that they successfully created 11 transgenic rhesus monkeys (eight first-generation and three second-generation) carrying human copies of MCPH1.

According to the research article, brain imaging and tissue section analysis showed an altered pattern of neuron differentiation and a delayed maturation of the neural system, which is similar to the developmental delay (neoteny) in humans.

Wild rhesus monkeys /VCG Photo

Neoteny in humans is the retention of juvenile features into adulthood. One key difference between humans and nonhuman primates is that humans require a much longer time to shape their neuro-networks during development, greatly elongating childhood, which is the so-called "neoteny."

The study also found that the transgenic monkeys exhibited better short-term memory and shorter reaction time compared to wild rhesus monkeys in the control group.

The researchers said that a transgenic monkey model is practical and to a large extent can mimic the human-specific status.

In future studies, transgenic nonhuman primates have the potential to provide important insights into basic questions of what makes humans unique, as well as into neurodegenerative and social behavior disorders that are difficult to study by other means, they said.

Strict animal experiments

Concerns may be raised when talking about experiment animals, while it has been worldwide recognized that the welfare of lab animals should be safeguarded.

Strict regulations and rules have been stipulated to regulate animal experiments.

A nonprofit organization, Association for Assessment and Accreditation of Laboratory Animal Care International (AAALAC), has been committed to promoting "the humane treatment of animals in science through voluntary accreditation and assessment programs."

Over 1,000 government agencies, enterprises and institutions from 47 countries have been certified by the association, with more than 80 from China, showing their commitment to "responsible animal care and use and good science."

Both the Chinese and U.S. institutes involved in the transgenic monkey research have got AAALAC accreditation.

At the same time, scientists are also seeking alternative methods for lab animals, according to Shanghai Institute of Materia Media, CAS, also with AAALAC accreditation, practicing the basic principles of "3R" – replace, reduce and refine.

(Cover: Rhesus macaques /VCG Photo)
(With input from Xinhua News Agency)

 

[JSCh]

PUBLIC RELEASE: 3-APR-2019
Newly discovered mechanism of plant hormone auxin acts the opposite way
Auxin accumulation at the inner bend of seedling leads to growth inhibition rather than stimulation as in other plant tissues

INSTITUTE OF SCIENCE AND TECHNOLOGY AUSTRIA

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Increased auxin accumulation (blue areas) in the concave side of the apical hook of Arabidopsis thaliana.
CREDIT: IST Austria - Marçal Gallemí Rovira/Eva Benková group

Increased levels of the hormone auxin usually promote cell growth in various plant tissues. Chinese scientists together with researchers from the Institute of Science and Technology Austria (IST Austria) have now shown that in special areas of the seedling, increased auxin levels trigger a different gene expression pathway leading to growth inhibition. The discovery, published in the journal Nature, helps to explain the formation of the typical bend or so called apical hook that helps the seedling to break through the soil following germination.

Varied auxin concentrations mediate distinct developmental outcomes in different plant tissues. For instance, auxin accumulating in stem tissues triggers a gene expression pathway that ultimately leads to increased cell elongation resulting in stem growth. A growth scenario, which cannot be explained in an analogous way, however, is the development of the apical hook that the early plant forms to protect its delicate growing apex when breaking through the soil. In the cells of the inner bend of the hook, i.e. the concave side, auxin accumulates; however, to grow into the form of a hook, the seedling's shoot must grow less at the inner concave than on the outer convex side. Scientists thus faced a paradox situation and asked themselves: Can auxin do something opposite from what it has been known to do in other parts of the plants?

One hormone--two different gene expressions

To solve the puzzle, the research group around Tongda Xu from the Chinese Academy of Sciences collaborated with IST Austria plant cell biologist Ji?í Friml and his postdoc fellow Zuzana Gelová. By testing various mutants of the model plant Arabidopsis thaliana, the scientists could reveal a previously unknown gene expression pathway triggered by auxin accumulation and leading to the inhibition of growth at the concave side of the hook. While the previously known pathway is located at the nucleus and involves the receptor protein TIR1 (Transport Inhibitor Response 1), this newly discovered pathway starts at the cell surface--and involves a different perception component, Transmembrane Kinase (TMK1), the function of which had been unclear.

A paradox and TMK1 explained

In the newly discovered mechanism, auxin activates TMK1 at the cell surface and triggers cleavage of the intracellular part of this protein. Within the cell, the cleaved part of TMK1 interacts with specific transcriptional repressors. While auxin degrades similar repressor proteins in the nucleus-based TIR1 pathway to trigger gene expression leading to cell growth, it stabilizes the repressors connected to the TMK1 pathway, resulting in growth inhibition rather than stimulation. Thus, TIR1 and TMK1 interact with different subsets of transcriptional proteins and therefore facilitate auxin signaling by two different mechanisms, allowing the shoot to grow on one side, but not the other. Co-author Jiří Friml: "We have wanted to understand for a long time how TMK1 works as well as whether and how auxin accumulation can function in two different ways. Thanks to our persistence and the major contributions of our Chinese colleagues, we now know both." Starting from here, it would also be worthwhile to the scientists to understand the full repertoire of the developmental process beyond the apical hook controlled by this novel auxin signaling pathway.


Newly discovered mechanism of plant hormone auxin acts the opposite way | EurekAlert! Science News

Min Cao, Rong Chen, Pan Li, Yongqiang Yu, Rui Zheng, Danfeng Ge, Wei Zheng, Xuhui Wang, Yangtao Gu, Zuzana Gelová, Jiří Friml, Heng Zhang, Renyi Liu, Jun He & Tongda Xu. TMK1-mediated auxin signalling regulates differential growth of the apical hook. Nature (2019). DOI: 10.1038/s41586-019-1069-7​

 

[JSCh]

PUBLIC RELEASE: 4-APR-2019
Ready, steady, go: 2 new studies reveal the steps in plant immune receptor activation

MAX PLANCK INSTITUTE FOR PLANT BREEDING RESEARCH

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The upper image depicts the pentameric wheel-like structure of the ZAR1 resistosome from above. In the lower panel depicting the resistosome in the side view, the funnel can be seen in light brown. PBL2 is colored in green and RKS1 in mustard. All other colors denote different domains of the ZAR1 protein.
CREDIT: Jijie Chai

Although separated by more than one billion years of evolution, plants and animals have hit upon similar immune strategies to protect themselves against pathogens. One important mechanism is defined by cytoplasmic receptors called NLRs that, in plants, recognize so-called effectors, molecules that invading microorganisms secrete into the plant's cells. These recognition events can either involve direct recognition of effectors by NLRs or indirect recognition, in which the NLRs act as 'guards' that monitor additional host proteins or 'guardees' that are modified by effectors. Host recognition of effectors, whether direct or indirect, results in cell death to confine microbes to the site of infection. However, until now, a detailed understanding of the mechanisms of action of plant NLRs has been lacking, and much of our understanding of how these molecules function in plants has been based on comparison with animal counterparts.

In two new studies published in the journal Science, Jijie Chai who is affiliated with Tsinghua University in Beijing as well as the University of Cologne and the Max Planck Institute for Plant Breeding Research together with the groups of Hong-Wei Zhang and Jian-Min Zhou at Tsinghua University and the Chinese Academy of Sciences in Beijing have now pieced together the sequence of molecular events that convert inactive NLR molecules into active complexes that provide disease resistance.

The authors focused their attentions on a protein called ZAR1, an ancient plant molecule that is likely to be of broad importance since it interacts with multiple 'guardees' to recognize unrelated bacterial effectors.

Using cryo-electron microscopy, Chai and co-authors observed that in the absence of bacterial effectors, ZAR1, together with the plant protein RKS1, is maintained in a latent state through interactions involving multiple domains of the ZAR1 protein. Upon infection, a bacterial effector modifies the plant 'guardee' PBL2, which then activates RKS1 resulting in huge conformational changes that first allow plants to swap ADP for ATP and then result in the assembly of a pentameric, wheel-like structure that the authors term the 'ZAR1 resistosome'.

One striking feature of this structure is its similarity with animal NLR proteins, which, once activated, also assemble into wheel-like structures that act as signaling platforms for cell death execution and immune signaling. However, one important difference between the structures offers a tantalizing clue as to how ZAR1 induces cell death. The authors could identify a highly ordered funnel-like structure in ZAR1 that tethers the resistosome to the plasma membrane and is required for cell death and disease resistance. The authors speculate that ZAR1 may form a pore in the plasma membrane and in this way perturb cellular function leading to immune signaling and cell death.

Other plant NLRs also assemble into complexes that associate with the plasma membrane and it is thus highly likely that Chai's findings have important general implications for understanding plant immunity. MPIPZ director Paul Schulze-Lefert, who was not involved in the studies, is in no doubt about the importance of the new studies: "This will become textbook knowledge."



Ready, steady, go: 2 new studies reveal the steps in plant immune receptor activation | EurekAlert! Science News

1. Jizong Wang, Jia Wang, Meijuan Hu, Shan Wu, Jinfeng Qi, Guoxun Wang, Zhifu Han, Yijun Qi, Ning Gao, Hong-Wei Wang, Jian-Min Zhou, Jijie Chai. Ligand-triggered allosteric ADP release primes a plant NLR complex. Science (2019). DOI: 10.1126/science.aav5868
2. Jizong Wang, Meijuan Hu, Jia Wang, Jinfeng Qi, Zhifu Han, Guoxun Wang, Yijun Qi, Hong-Wei Wang, Jian-Min Zhou, Jijie Chai. Reconstitution and structure of a plant NLR resistosome conferring immunity. Science (2019). DOI: 10.1126/science.aav5870

 

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PUBLIC RELEASE: 4-APR-2019
The Lancet: Moderate alcohol consumption does not protect against stroke, study shows
Blood pressure and stroke risk increase steadily with increasing alcohol intake, and previous claims that 1-2 alcoholic drinks a day might protect against stroke are dismissed by new evidence from a genetic study involving 160,000 adults

THE LANCET

Blood pressure and stroke risk increase steadily with increasing alcohol intake, and previous claims that 1-2 alcoholic drinks a day might protect against stroke are dismissed by new evidence from a genetic study involving 160,000 adults.

Studies of East Asian genes that strongly affect how much alcohol people choose to drink show that alcohol itself directly increases blood pressure and the chances of having a stroke, according to a new study published in The Lancet. It was known that stroke rates were increased by heavy drinking, but it wasn't known whether they were increased or decreased by moderate drinking.

Although people who have one or two alcoholic drinks a day had previously been observed to have a slightly lower risk of stroke and heart attack than non-drinkers, it was not known whether this was because moderate drinking was slightly protective, or whether it was because non-drinkers had other underlying health problems (eg, being former drinkers who had stopped because of illness). At least for stroke, the genetic evidence now refutes the claim that moderate drinking is protective.

In East Asian populations, there are common genetic variants that greatly reduce alcohol tolerability, because they cause an extremely unpleasant flushing reaction after drinking alcohol. Although these genetic variants greatly reduce the amount people drink, they are unrelated to other lifestyle factors such as smoking. Therefore, they can be used to study the causal effects of alcohol intake.

As the genetic factors that strongly affect drinking patterns are allocated randomly at conception and persist lifelong, this study is the genetic equivalent of a large randomised trial, and can therefore sort out cause-and-effect relationships reliably - a method called "Mendelian randomisation."

Lead author Dr Iona Millwood, from the Medical Research Council Population Health Research Unit at the University of Oxford, UK, says: "Using genetics is a novel way to assess the health effects of alcohol, and to sort out whether moderate drinking really is protective, or whether it's slightly harmful. Our genetic analyses have helped us understand the cause-and-effect relationships." [1]

Researchers from Oxford University, Peking University, and the Chinese Academy of Medical Sciences led a large collaborative study of over 500,000 men and women in China who were asked about their alcohol intake and followed for ten years. In over 160,000 of these adults the researchers measured two genetic variants (rs671 and rs1229984) that substantially reduce alcohol intake.

Among men, these genetic variants caused a 50-fold difference in average alcohol intake, from near zero to about four units (drinks) per day. The genetic variants that decreased alcohol intake also decreased blood pressure and stroke risk. From this evidence, the authors conclude that alcohol increases the risk of having a stroke by about one-third (35%) for every four additional drinks per day (280 g of alcohol a week), with no protective effects of light or moderate drinking.

Professor Zhengming Chen, co-author from the Nuffield Department of Population Health, University of Oxford, says: "There are no protective effects of moderate alcohol intake against stroke. Even moderate alcohol consumption increases the chances of having a stroke. The findings for heart attack were less clear-cut, so we plan to collect more evidence." [1]

Of the men with genetic measurements, about 10,000 had a stroke and 2,000 had a heart attack during about ten years of follow-up, so more information is needed on heart attacks.

Few women in China drink alcohol (less than 2% of women in the study drank in most weeks, and when they did drink they consumed less than men), and the genetic variants that cause alcohol intolerance had little effect on blood pressure or stroke risk. Women in this study therefore provide a useful control group, which helps confirm that the effects of these genetic variants on stroke risk in men were caused by drinking alcohol, not by some other mechanism.

The authors highlight that it would be impossible to do such a study in Western populations, where almost nobody has the relevant genetic variants. However, these findings about the effects of alcohol in Asia should be applicable worldwide. Because the study was conducted in China, the alcohol consumed was mainly spirits, but they expect the findings to apply to alcohol in other drinks.

In China, more years of life are lost to stroke than to any other disease. This study estimates that, among Chinese men, alcohol is a cause of 8% of all strokes from a blood clot in the brain and 16% of all strokes from bleeding into the brain.

Co-author Professor Liming Li, from Peking University, says: "Stroke is a major cause of death and disability. This large collaborative study has shown that stroke rates are increased by alcohol. This should help inform personal choices and public health strategies." [1]

Writing in a linked Comment, Professor Tai-Hing Lam and Dr Au Yeung, from the University of Hong Kong, Hong Kong Special Administrative Region, China, call for a WHO Framework Convention for Alcohol Control (FCAC), similar to the Framework Convention on Tobacco Control (FCTC): "Alcohol control is complex and stronger policies are required. The alcohol industry is thriving and should be regulated in a similar way to the tobacco industry."


The Lancet: Moderate alcohol consumption does not protect against stroke, study shows | EurekAlert! Science News

Iona Y Millwood, Robin G Walters, Xue W Mei, Yu Guo, Ling Yang, Zheng Bian, Derrick A Bennett, Yiping Chen, Caixia Dong, Ruying Hu, Gang Zhou, Bo Yu, Weifang Jia, Sarah Parish, Robert Clarke, George Davey Smith, Rory Collins, Michael V Holmes, Liming Li, Richard Peto, Zhengming Chen, for the China Kadoorie Biobank Collaborative Group. Conventional and genetic evidence on alcohol and vascular disease aetiology: a prospective study of 500 000 men and women in China. The Lancet (2019). DOI: https://doi.org/10.1016/S0140-6736(18)31772-0​

 

[JSCh]

Scientists Find the Temporal Contrast Degradation Mechanisms---Chinese Academy of Sciences
Apr 01, 2019

10-petawatt laser pulses have potential applications for the acceleration of charged particles (electrons, protons, and heavier ions) and the generation of coherent or incoherent high-energy radiation. In these applications, however, the temporal contrast of the laser should be high enough to restrict destructive preplasma dynamics.

The Shanghai Superintense Ultrafast Laser Facility (SULF) is a large-scale project that aims to deliver 10 PW laser pulses; and the output temporal contrast is a key task for SULF to satisfy the requirements of physical experiments.

In order to improve the temporal contrast, researchers from the Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, have built a high-contrast front end for the SULF-10PW laser by combining cross-polarized wave generation and femtosecond optical parametric amplification.

The research, entitled "High-contrast front end based on cascaded XPWG and femtosecond OPA for 10-PW-level Ti:sapphire laser", had been published in Optics Express.

Recently, based on this work, researchers further investigated the evolution of the temporal contrast in the SULF-10PW laser and found the degradation mechanisms of the temporal contrast.

In this work, the researchers first established a simulation model to describe the temporal contrast evolution. The model considered the generation and amplification of the ASE (amplified spontaneous emission), and the amplification of the main pulses.

Then, a proof-of-principle experiment was conducted. The experimental results coincided well with the simulation results.

The results indicated that the energy loss of clean seed pulses in the grism pair was a major factor in contrast degradation.

Because of the low transmission efficiency of the grism pair (~10%), the temporal contrast was degraded by one order of magnitude. The spectral shaping filter in the regenerative amplifier degraded the temporal contrast by increasing the intra-cavity loss.

Also, the temporal contrast was further degraded as the gain increased in multi-stage Ti:sapphire amplifiers.

According to the investigations described above, the design of the SULF-10PW laser was further improved. It was predicted that the temporal contrast could be enhanced by more than one order of magnitude at a peak power of 10 PW following the improvements. The in-depth research could provide guidelines for improving the temporal contrast in ultrahigh-peak-power Ti:sapphire lasers.

The research, entitled "Investigation of the temporal contrast evolution in a 10-PW-level Ti:sapphire laser facility", was published in Optics Express.

This work was supported by the National Natural Science Foundation of China, the International S&T Cooperation of China Program, the Strategic Priority Research Program of the Chinese Academy of Sciences, the Shanghai Municipal Science and Technology Major Project and the Youth Innovation Promotion Association, CAS.

Fig. (a) Layout of the current SULF-10PW laser. (b) Evolution of the temporal contrast. (Image by SIOM)

 

[JSCh]

Physics - Synopsis: Ultrafast Oscilloscope for Ultrashort Electron Beam
April 9, 2019
Driving an electron beam into a helical pattern with terahertz electromagnetic pulses allows researchers to measure the beam’s complete shape with femtosecond resolution.

L. Zhao et al., Phys. Rev. Lett. (2019)​

Ultrashort electron beams are used in applications ranging from particle accelerators to biological imaging. Optimal operation of these technologies requires an understanding of the full time-domain behavior of the electron beam. However, existing characterization methods lack sufficient temporal resolution to describe the shape and arrival time of electron bursts, particularly when the electrons have high energies. Lingrong Zhao of Shanghai Jiao Tong University in China and colleagues now demonstrate a solution to this problem with an oscilloscope device that can encode the entire temporal profile of a relativistic electron beam using a THz pulse.

Traditional cathode-ray oscilloscopes measure electrical signals using a beam of electrons. In the new oscilloscope, Zhao and colleagues characterize an electron beam using a high-frequency, circularly polarized external electromagnetic pulse. This THz pulse interacts with the beam as they both pass through a dielectric waveguide, forcing the electrons into a helical path. As a result, different parts of the beam hit the oscilloscope screen in different places, spreading the beam’s temporal profile spatially across the detector.

In their demonstration of the new method, the team measured the shape of an ultrashort relativistic electron beam with a resolution of 24 femtoseconds. They also determined the beam’s arrival time to within 3 femtoseconds. They say that their oscilloscope could be implemented in existing free-electron lasers and ultrafast electron diffraction experiments, providing these technologies with higher time-resolution imaging capabilities. Zhao and colleagues also believe that their oscilloscope could achieve subfemtosecond resolution if they either increase the electric field strength of the THz pulse or decrease the diameter of the waveguide.

This research is published in Physical Review Letters.

–Matthew R. Francis
Matthew R. Francis is a physicist and freelance science writer based in Cleveland, Ohio.

Terahertz Oscilloscope for Recording Time Information of Ultrashort Electron Beams
Lingrong Zhao, Zhe Wang, Heng Tang, Rui Wang, Yun Cheng, Chao Lu, Tao Jiang, Pengfei Zhu, Long Hu, Wei Song, Huida Wang, Jiaqi Qiu, Roman Kostin, Chunguang Jing, Sergey Antipov, Peng Wang, Jia Qi, Ya Cheng, Dao Xiang, and Jie Zhang
Phys. Rev. Lett. 122, 144801 (2019)

Published April 9, 2019​

 

[JSCh]

An integrated microfludic system for PET tracers synthesis invented in ZJU
2019-04-10 Global Communications

Radioactive tracers are needed during the Positron Emission Tomography (PET) scan, a nuclear medicine functional imaging technique. Dependent on what to detect, different ligands are used for different imaging purposes, including the measurement of glucose metabolic rate, the quantification of cardiac perfusion or the determination of gene expression. Up to date, there are more than 100 tracers that have been designed and this number keeps increasing. However, the synthesis of PET tracers is lacking behind its application and the supply in China is highly dependent on imports.

“Low cost, multiple modules, fast synthesis and automatic reaction, these are four advantages of our system. On this platform, a varaity of PET tracers can be synthesized using modular design strategy of microfludics”, said ZHANG Hong, director, Institute of Nuclear Medicine and Molecular Imaging. Furthermore, it is the first device of this kind in China with full IP rights with 9 patents. Several key energy consumption indicators, such as Radiation volume, preparation time, precursor volume, solvent consumption, power consumption, equipment cost, are 62%-98% lower compared to available devices. The invention of this integrated microfludic system will greatly expand clinical application of PET in personalized and precision medicine.

The whole synthetic procedure is fabricated in a small “black” box with 35 cm ×25 cm × 28 cm in dimension and about 7-8 kg in weight. The diameter of the thinnest channel is even smaller than the size of a human hair. The micro-size of the device lead to the high surface to volume ratio and resulting fast thermal heating and cooling rates of reagents can lead to reduced reaction times, increased synthesis yields and reduced by-products.

According to the synthetic requirements of different probes, multiple modules in reactors are designed in this device. This plug-and-Play strategy can be programmed remotely through a software system.

Other inventors of this system are TIAN Mei, PAN Jianzhang, FANG Qun、LEI Ming, XU Guangming and HE Qinggang.


An integrated microfludic system for PET tracers synthesis invented in ZJU | Zhejiang University

 

[JSCh]

APRIL 11, 2019
Near-atomic map of parathyroid hormone complex points toward new therapies for osteoporosis
by Van Andel Research Institute

Cryo-EM structure of LA-PTH-bound human PTH1R in complex with Gs Credit: Zhao LH et al. 2019. Structure and dynamics of the active human parathyroid hormone receptor-1. Science.

An international team of scientists has mapped a molecular complex that could aid in the development of better medications with fewer side effects for osteoporosis and cancer.

The near-atomic resolution images depict parathyroid hormone receptor-1 (PTH1R), a molecule that conveys signals to and from cells, interacting with two key messengers—a molecule that mimics parathyroid hormone, one of the most important regulators of calcium levels in the body, and a stimulatory G protein, a molecule that mediates bone turnover.

The findings, published today in Science, give researchers a better blueprint for designing drugs for osteoporosis and other conditions such as chachexia, which causes severe weakness and weight loss that can be fatal in cancer patients.

Globally, more than 200 million people have osteoporosis and even more have low bone density. In the coming years, public health experts expect these numbers to rise, fueled in part by an aging population. They also fear an increase in osteoporosis-related fractures due to fewer people taking current medications out of concern over rare side effects.

"The understanding of how all of these molecules fit together has been a missing piece of the puzzle since the discovery of parathyroid hormone 80 years ago," said H. Eric Xu, Ph.D., a professor at Van Andel Research Institute (VARI) and co-corresponding author of the study. "It's a big step forward that we hope will one day help people around the world."

PTH1R is a molecular communication conduit between cells and their environments that fosters development of the bones, skin and cartilage, and regulates levels of calcium in the blood.

To do this, it interacts with molecular messengers such as the parathyroid hormone, which ensures the blood stream has the appropriate amount of calcium to maintain healthy function.

However, too much parathyroid hormone can wreak havoc on the body, spiking the amount of calcium in the blood to dangerous levels, promoting the formation of kidney stones and leaching calcium from bones, which can cause devastating fractures. Too little bogs down metabolism, and contributes to fatigue, weight gain, depression and a host of other issues.

Today's findings also provide insight into G protein-coupled receptors (GPCRs), a family of signaling molecules to which PTH1R belongs. Taken together, GPCRs are targeted by nearly 30 percent of medications currently on the market.

GPCRs are notoriously difficult to visualize using traditional X-ray crystallography methods; to date, only about 40 out of more than 800 total GPCRs have had their structures determined. To visualize today's structure, the team used a groundbreaking technique called cryo-electron microscopy (cryo-EM), which is capable of imaging molecules in unprecedented clarity and can more easily image molecules like GPCRs that are embedded in the cell membrane.


Near-atomic map of parathyroid hormone complex points toward new therapies for osteoporosis | MedicalXpress

Li-Hua Zhao, Shanshan Ma, Ieva Sutkeviciute, Dan-Dan Shen, X. Edward Zhou, Parker W. de Waal, Chen-Yao Li, Yanyong Kang, Lisa J. Clark, Frederic G. Jean-Alphonse, Alex D. White, Dehua Yang, Antao Dai, Xiaoqing Cai, Jian Chen, Cong Li, Yi Jiang, Tomoyuki Watanabe, Thomas J. Gardella, Karsten Melcher, Ming-Wei Wang, Jean-Pierre Vilardaga, H. Eric Xu, Yan Zhang. Structure and dynamics of the active human parathyroid hormone receptor-1. Science (2019). DOI: 10.1126/science.aav7942.​