China Science & Technology Forum

[JSCh]

Catalytic fix for nitrogen fixation
BY EMMA STOYE
15 NOVEMBER 2018

Single-atom ruthenium catalyst doubles efficiency of electrochemical reduction of nitrogen to ammonia

Source: © Elsevier Ltd
Single ruthenium atoms efficiently catalyse nitrogen electroreduction and adding zirconium dioxide supresses the hydrogen evolution reaction

By developing a more effective ruthenium catalyst, researchers in China have improved the efficiency of electrochemical nitrogen fixation, a process that could one day replace the Haber–Bosch process as a greener way of making ammonia.

While the Haber–Bosch process is still the preferred method for producing ammonia and nitrogen-based fertilisers on an industrial scale, researchers have been exploring alternatives that don’t require such high temperatures and pressures. One approach that is potentially more sustainable is the electrochemical reduction of N2 to NH3, which renewable energy could power. But this suffers from low current-conversion efficiency, with the best electrodes and catalysts achieving around 10% efficiency at ambient temperature conditions – too low for industrial scale-up.

Now, Zhenyu Sun at Beijing University of Chemical Technology in China and colleagues have managed to improve electrochemical nitrogen fixation with clever catalyst design. Previous work had shown that single atoms of a metal catalyst dispersed on a support can be more effective than larger particles of the metal because the catalytically active sites are homogeneous and the metal can work at maximum efficiency. So Sun’s team built a single-atom catalyst for electrochemical nitrogen reduction using ruthenium – a metal that had already shown promise for the reaction – supported on nitrogen-doped porous carbon. They showed that using their catalyst with an aqueous solution of N2 could increase the current-conversion efficiency of its reduction to ammonia to 21%, far outperforming other metal-based catalysts.

They also showed that adding zirconium dioxide to their catalyst improved its specificity for nitrogen and inhibited the reduction of water to hydrogen gas, a competing reaction. This resulted in ammonia yields twice as high as that of the next best reported catalyst.

‘We believe that the development of single-atom catalysts opens a potentially alternative avenue for efficient ammonia synthesis,’ the researchers conclude, adding that the approach ‘deserves further research in N2 fixation’.

Joshua McEnaney, who works on electrochemical nitrogen reduction at Stanford University in the US, says this approach offers an ‘important path’ towards sustainably producing ammonia and fertilisers, and that Sun’s group’s work ‘taps into exciting new types of catalysts with promising NH3 selectivity’. ‘It will be interesting to see if similarly engineered sites with different core atoms or support structures can also work for this reaction, and if partial current densities toward NH3 can be improved, ‘ he says.

References
H Tao et al, Chem, 2018, DOI: 10.1016/j.chempr.2018.10.007
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Catalytic fix for nitrogen fixation | Research | Chemistry World

 

[JSCh]

New dates for ancient stone tools in China point to local invention of complex technology
November 19, 2018 11.11am EST

You probably think of new technologies as electronics you can carry in a pocket or wear on a wrist. But some of the most profound technological innovations in human evolution have been made out of stone. For most of the time that humans have been on Earth, they’ve chipped stone into useful shapes to make tools for all kinds of work.

In a study just published in Nature, we’ve dated a distinctive and complex method for making stone tools to a much earlier timeframe in China than had previously been accepted. Archaeologists had thought that artifacts of this kind had been carried into China by groups migrating from Europe and Africa. But our new discovery, dated to between 170,000 and 80,000 years ago, suggests that they could have been invented locally without input from elsewhere, or come from much earlier cultural transmission or human migration.

Several different species of humans lived on Earth at this time, including modern ones like us. But we haven’t found any human bones from this site, so don’t know which species of human made these tools.

These Chinese artifacts provide one more piece of evidence that changes the way we think about the origin and spread of new stone tool technologies. And intriguingly we made our discovery based on artifacts that had been excavated decades ago.


Con't -> New dates for ancient stone tools in China point to local invention of complex technology | The Conversation

 

[JSCh]

PUBLIC RELEASE: 19-NOV-2018
Human images from world's first total-body scanner unveiled
1st-of-its kind scanner to roll out in Sacramento in spring 2019

UNIVERSITY OF CALIFORNIA - DAVIS

This is an EXPLORER image showing glucose metabolism throughout the entire human body. This is the first time a medical imaging scanner has been able to capture a 3D image of the entire human body simultaneously. CREDIT: UC Davis and Zhongshan Hospital, Shanghai

The brainchild of UC Davis scientists Simon Cherry and Ramsey Badawi, EXPLORER is a combined positron emission tomography (PET) and x-ray computed tomography (CT) scanner that can image the entire body at the same time. Because the machine captures radiation far more efficiently than other scanners, EXPLORER can produce an image in as little as one second and, over time, produce movies that can track specially tagged drugs as they move around the entire body.

The developers expect the technology will have countless applications, from improving diagnostics to tracking disease progression to researching new drug therapies.

The first images from scans of humans using the new device will be shown at the upcoming Radiological Society of North America meeting, which starts on Nov. 24th in Chicago. The scanner has been developed in partnership with Shanghai-based United Imaging Healthcare (UIH), which built the system based on its latest technology platform and will eventually manufacture the devices for the broader healthcare market.

"While I had imagined what the images would look like for years, nothing prepared me for the incredible detail we could see on that first scan," said Cherry, distinguished professor in the UC Davis Department of Biomedical Engineering. "While there is still a lot of careful analysis to do, I think we already know that EXPLORER is delivering roughly what we had promised.

Badawi, chief of Nuclear Medicine at UC Davis Health and vice-chair for research in the Department of Radiology, said he was dumbfounded when he saw the first images, which were acquired in collaboration with UIH and the Department of Nuclear Medicine at the Zhongshan Hospital in Shanghai.

"The level of detail was astonishing, especially once we got the reconstruction method a bit more optimized," he said. "We could see features that you just don't see on regular PET scans. And the dynamic sequence showing the radiotracer moving around the body in three dimensions over time was, frankly, mind-blowing. There is no other device that can obtain data like this in humans, so this is truly novel."

Badawi and Cherry first conceptualized a total-body scanner 13 years ago. Their idea was kick-started in 2011 with a $1.5 million grant from the National Cancer Institute, which allowed them to establish a wide-ranging consortium of researchers and other collaborators. And it got a giant boost in 2015 with a $15.5 million grant from the NIH. The funding allowed them to team up with a commercial partner and get the first EXPLORER scanner built.

Cherry said he expects EXPLORER will have a profound impact on clinical research and patient care because it produces higher-quality diagnostic PET scans than have ever been possible. EXPLORER also scans up to 40 times faster than current PET scans and can produce a diagnostic scan of the whole body in as little as 20-30 seconds.

Alternatively, EXPLORER can scan with a radiation dose up to 40 times less than a current PET scan, opening new avenues of research and making it feasible to conduct many repeated studies in an individual, or dramatically reduce the dose in pediatric studies, where controlling cumulative radiation dose is particularly important.

"The tradeoff between image quality, acquisition time and injected radiation dose will vary for different applications, but in all cases, we can scan better, faster or with less radiation dose, or some combination of these," Cherry said.

For the first time, an imaging scanner will be able to evaluate what is happening in all the organs and tissues of the body simultaneously. For example, it could quantitatively measure blood flow or how the body takes up glucose everywhere in the body. Researchers envision using the scanner to study cancer that has spread beyond a single tumor site, inflammation, infection, immunological or metabolic disorders and many other diseases.

UC Davis is working closely with UIH to get the first system delivered and installed at the EXPLORER Imaging Center in leased space in Sacramento, and the researchers hope to begin research projects and imaging patients using EXPLORER as early as June 2019. The UC Davis team also is working closely with Hongcheng Shi, director of Nuclear Medicine at Zhongshan Hospital in Shanghai to continue and expand the scope of early human studies on the scanner.

"I don't think it will be long before we see at a number of EXPLORER systems around the world," Cherry said. "But that depends on demonstrating the benefits of the system, both clinically and for research. Now, our focus turns to planning the studies that will demonstrate how EXPLORER will benefit our patients and contribute to our knowledge of the whole human body in health and disease."


Human images from world's first total-body scanner unveiled | EurekAlert! Science News

 

[JSCh]

Viewpoint: Dissecting the Mass of the Proton
André Walker-Loud, Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
November 19, 2018• Physics 11, 118

A calculation determines four distinct contributions to the proton mass, more than 90% of which arises entirely from the dynamics of quarks and gluons.

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APS/Alan Stonebraker
Figure 1: The proton is comprised of two up quarks and one down quark, but the sum of these quark masses is a mere 1% of the proton mass. Using lattice QCD, Yang and colleagues determined the relative contributions of the four sources of the proton mass [1]. (The cumulative contributions in MeV/c2 are shown on the dark green rectangles.)

Nearly all the mass of known matter is contained within protons and neutrons—the particles that make up the nuclei of atoms. But how do the protons and neutrons acquire their mass? Each of these particles, or “nucleons,” is composed of a dense, frothing mess of other particles: quarks, which have mass, and gluons, which do not. Yet the quark masses only add up to a mere 1% of a proton or neutron’s mass, with the bulk of the proton mass coming purely from the motion and confinement of quarks and gluons. Yi-Bo Yang of Michigan State University, East Lansing, and colleagues have now quantified, for the first time, four separate contributions to the proton’s mass with a calculation based on quantum chromodynamics (QCD), the fundamental theory of the strong interaction in the nucleus and a cornerstone of the standard model of particle physics [1]. While this four-part decomposition has been known for more than 20 years [2], physicists' understanding of it has been only qualitative.

The quarks that make up the proton and neutron are fundamental particles, which get their masses through the Higgs mechanism. The same mechanism doesn’t explain the mass of the proton, which is comprised of two up quarks ( 2.4MeV∕c2 each) and one down quark ( 5.0MeV∕c2) [3]. Clearly, the sum of these three masses falls far short of the actual proton mass, 938.27MeV∕c2. Now, quantum mechanics tells us there is also mass (or equivalently, energy) associated with the confinement of the quarks into the proton, whose diameter is about 10−15m. Using an uncertainty principle argument, the confined position of the particles translates into a large momentum and should add about 300MeV∕c2—in the right ball park of the proton mass but still too small. (Similar arguments apply to the neutron, which is comprised of two down quarks and an up quark.)

In fact, accurate standard model predictions of both the proton and neutron mass have existed for a decade [4]. At the low energies relevant to a nucleus, these masses can be predicted from just three parameters: an overall mass scale, which is dynamically generated in QCD, and the up and down quark parameters. The proton and neutron masses are known much more precisely from experiment than will ever be possible from standard model predictions. However, physicists would like to understand how the masses emerge from QCD, much the same way they can predict the spectrum of hydrogen from quantum theory.

Yang and colleagues have done just this, determining for the first time the various contributions to the proton mass that arise from quark and gluon dynamics [1]. The researchers rely on a powerful method known as lattice QCD, which places quarks on the sites of a lattice and gluons on the links between them. This rigorous representation of QCD can be implemented numerically, and it is the only QCD-based method that can make quantitative predictions on length scales comparable to the proton or larger. (At these scales, the interactions between quarks and gluons are so strong, they cannot be handled with Feynman diagrams and other “perturbative” methods.) However, lattice QCD is an expensive technique. The discretization creates errors, and to remove them entails taking the lattice spacing, a, to zero. This step is achieved in practice by performing multiple calculations at different values of a, at a high numerical cost that scales as a-6. Nevertheless, lattice QCD has matured significantly in recent years, allowing for the most precise determination of the quark masses [5] and many properties of light and heavy mesons [3], which are comprised of a quark and an antiquark.

A three-quark particle like the nucleon is exponentially more complicated for lattice QCD, and successful calculations, with all sources of uncertainty controlled, have been rare. In their work, Yang and collaborators overcome some of the complications by using new computational methods that they, along with others, developed [6–8]. These advances enabled them to compute the contribution to the proton mass from four sources [2] known as the quark condensate ( ∼9%), the quark energy ( ∼32%), the gluonic field strength energy ( ∼37%), and the anomalous gluonic contribution ( ∼23%) (Fig. 1). The smallest contribution, the quark condensate, is a mixture of the up and down quarks and a “sea” of virtual strange quarks, and it is the only one that would vanish if the quark masses were zero. The other three terms are all related to the dynamics of the quarks and gluons and their confinement within the proton. The quark energy and gluonic field strength equate to the kinetic energy of the confined quarks and confined gluons, respectively. The anomalous term is a purely quantum effect. It is associated with the QCD mass scale and consists of contributions from condensates of all quark flavors, including the strange, charm, bottom, and top quarks. The calculation by Yang and colleagues shows that, if the up, down, and strange quark masses were all zero, the proton would still have more than 90% of its experimental mass. In other words, nearly all the known mass in the Universe comes from the dynamics of quarks and gluons.

Physicists have long wanted to understand the emergence of the nucleon mass in terms of the standard model, and the findings from Yang and co-workers are an important contribution to that goal. Their work and other works like it also signify a new era, in which our understanding of nucleons is increasingly shaped by quantitative predictions based on lattice QCD. Just this year, researchers used lattice QCD to determine the nucleon axial charge, a ubiquitous quantity in nuclear physics, with an unprecedented 1% precision [9]. Lattice QCD, coupled with powerful analytic methods for simplifying QCD calculations, will lead to a better understanding of the substructure of the nucleon [10], which is being explored at various colliders around the world and would be one focus of a proposed machine called the Electron-Ion Collider. Ultimately, the hope is that lattice QCD can be applied to a nucleus (multiple nucleons). Nuclei are used as detectors in several experimental searches for beyond-standard-model physics, such as dark matter, a permanent electric dipole moment, and neutrinoless double-beta decay. Interpreting these experiments will require a quantitative understanding of nuclear physics that is rooted in the standard model. This sort of complex problem is increasingly in the realm of lattice QCD thanks to the availability of the near-exascale computers, Sierra and Summit, which are coming online now and are 10 to 15 times more powerful than even those used by Yang and co-workers.

This research is published in Physical Review Letters.

Proton Mass Decomposition from the QCD Energy Momentum Tensor
Yi-Bo Yang, Jian Liang, Yu-Jiang Bi, Ying Chen, Terrence Draper, Keh-Fei Liu, and Zhaofeng Liu
Phys. Rev. Lett. 121, 212001 (2018)
Published November 19, 2018

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Physics - Viewpoint: Dissecting the Mass of the Proton

 

[JSCh]

PUBLIC RELEASE: 20-NOV-2018
HSPC 'Seeds' reveal VCAM-1+ macrophage role in homing process
CHINESE ACADEMY OF SCIENCES HEADQUARTERS

Hematopoietic Stem and Progenitor Cells (HSPCs) give rise to all blood lineages that support people's life. HSPCs, like seeds, need a suitable microenvironment to maintain their function.

A process called "homing" allows HSPCs to anchor in their niches in order to expand and differentiate. Unique niche microenvironments, composed of various blood vessels and other niche components, including stromal cells, regulate this process.

To study the detailed architecture of the microenvironment and the regulation mechanism of homing, Prof. PAN Weijun's group at the Shanghai Institute of Nutrition and Health of Chinese Academy of Sciences used a zebrafish model to analyze the entire dynamic process of HSPC homing in vivo. The results entitled "VCAM-1+ macrophages guide the homing of HSPCs to a vascular niche" was published in Nature on Nov. 19, 2018.

By using a combination of advanced live imaging and a cell labeling-tracing system, researchers performed a high-resolution analysis of HSPC homing in zebrafish caudal hematopoietic tissue (CHT, equivalent to the fetal liver in mammals).

Compared to itga4 mutants with homing defects, successful HSPC retention was defined in CHT as the lodgement of HSPCs for more than 30 minutes.

The researchers also found that HSPCs preferred to stay at retention "hotspots" associated with venous capillaries, which are largely localized at the venous capillary confluence points connected to the caudal vein plexus.

Further study showed that VCAM-1+ macrophages patrolling the inner surface of the venous plexus interact with HSPCs in an ITGA4-dependent manner and direct HSPC retention.

These cells, named "usher cells," guide HSCP homing to two types of vascular niches. Usher cells, together with endothelial cells, help HSPC homing through distinct mechanisms.

This study dissects the temporal-spatial rules of HSPC retention, provides new insights into the mechanism for HSPC homing, and reveals the essential role of a VCAM-1+ macrophage population with patrolling behavior in HSPC retention.



HSPC 'Seeds' reveal VCAM-1+ macrophage role in homing process | EurekAlert! Science News

Dantong Li, Wenzhi Xue, Mei Li, Mei Dong, Jianwei Wang, Xianda Wang, Xiyue Li, Kai Chen, Wenjuan Zhang, Shuang Wu, Yingqi Zhang, Lei Gao, Yujie Chen, Jianfeng Chen, Bo O. Zhou, Yi Zhou, Xuebiao Yao, Lin Li, Dianqing Wu, Weijun Pan. VCAM-1+ macrophages guide the homing of HSPCs to a vascular niche. Nature (2018). DOI: 10.1038/s41586-018-0709-7​

 

[JSCh]

The awakening of an innovative China
Source: Xinhua| 2018-11-20 10:50:43|Editor: Yang Yi


BEIJING, Nov. 20 (Xinhua) -- Under a blue spotlight lies a mouse's brain immersed in liquid. A diamond blade slowly peels off a layer of brain tissue that is only one micron thick.

The layer is scanned and imaged. About 10,000 layers will be peeled off to get a map of the whole mouse brain.

The images of the colorful neural and vascular systems of the brain shown on the computer look like intricate highway networks. This is the world's clearest map of a mammal brain.

Dozens of such instruments are working round the clock in the spotless labs of the Suzhou Institute for Brainsmatics of the Huazhong University of Science and Technology (HUST), located in the Suzhou Industrial Park, in east China's Jiangsu Province. Nearby are the ancient Suzhou Gardens, famous for their inventive and exquisite design and oriental aesthetics.

The journal Nature recently reported the construction of the brain-imaging institute in Suzhou, arousing great interest in academic circles.

"We have achieved success with mice, and are making efforts to map the brains of primates which are more advanced and complicated," says Li An'an, vice-director of the institute.

"Our ultimate goal is to lead the world to get a precise map of the human brain, which will help us uncover its secrets," Li says.

This is only one of China's achievements at the frontier of science and technology.

In his book on Science and Civilization in China, Joseph Needham, a British science historian, described China as a great country of invention and creation, but falling behind in modern times.

In the 20th Century, few Chinese participated in world's major scientific and technological advances.

But the situation is changing rapidly. From Internet development to brain study, from probing space to exploring the deep sea, from observing the universe to researching micro particles, Chinese are working in almost all fields of science and technology.

In a cave in Wuhan, capital of central China's Hubei Province, scientists from HUST have measured the gravitational constant for more than 30 years, and obtained the most accurate result in the world recently.

Isaac Newton discovered the principle of gravitation more than 300 years ago, but the measurement of the gravitational constant had always been inaccurate.

"Precise measurement of gravitational constant is important for deeper understanding of gravity, and the measurement technology could be applied to searching for mineral deposits and navigation. The study might also help us figure out whether the universe has additional dimensions as surmised by Stephen Hawking, which might enable humans to traverse space and time in the future," says Tu Liangcheng, director of HUST's gravitation center.

China has intensified efforts to explore the universe in recent years to reclaim its pride in its outstanding achievements in astronomy in ancient times.

As early as 4,000 years ago, China had full-time astronomy officials and the world's earliest record of Halley's comet. The length of a year was measured and determined by Chinese astronomers more than 700 years ago, in line with today's Gregorian calendar.

China recently built the Five-hundred-meter Aperture Spherical Radio Telescope (FAST), the world's largest single-dish radio telescope. It has discovered dozens of new pulsars.

Scientists at China's Purple Mountain Observatory (PMO) and other institutions are pushing forward the construction of an observatory on the inland icecap in Antarctica.

"That will definitely be a world leader," says Shi Shengcai, director of the department of Antarctic and radio astronomy at PMO.

Completed in 1934, PMO was the first modern observatory built by Chinese. The original intention of constructing it was to avoid the monopoly of astronomical research by Western colonialists in China.

In its beautiful newly built office park in the suburb of Nanjing, capital of Jiangsu Province, scientists are working on the next-generation space detector to search for dark matter.

Chinese ideologist and philosopher Zhuangzi, who lived more than 2,000 years ago, believed material structure could be divided infinitely. Chinese scientists today continue exploration of the microcosmic world, with many breakthroughs in recent years in fields such as quantum communication, neutrino and iron-based superconductivity.

The Suzhou Nanomicro Technology Co., Ltd. is a private nano technology firm. It develops nano material that looks like white powder, but is actually tiny spheres thinner than hair with strong absorbability, which can be used in pharmaceuticals and liquid crystal displays.

"We have broken the technical monopoly of the United States and Japan, and saved hundreds of millions of dollars in import costs for China," says Jiang Biwang, chairman of Nanomicro.

More young Chinese are involved in innovation. The Suzhou Novosense Microelectronics Co., Ltd. was set up five years ago to develop core chips for sensors and isolators. All the founders of the company were born after 1980.

Wang Shengyang, CEO of the firm, says that R&D personnel account for more than half of the staff.

Statistics show China's R&D investment in 2016 exceeded the total of the EU, and was second only to the United States, accounting for 21 percent of the global R&D investment. China has the world's largest number of R&D personnel, and ranks second in the world in the number of scientific papers published in international journals. Scientific and technological advances contribute to 55.3 percent of the economic growth in China.

 

[JSCh]

PUBLIC RELEASE: 20-NOV-2018
HSPC 'Seeds' reveal VCAM-1+ macrophage role in homing process
CHINESE ACADEMY OF SCIENCES HEADQUARTERS

Hematopoietic Stem and Progenitor Cells (HSPCs) give rise to all blood lineages that support people's life. HSPCs, like seeds, need a suitable microenvironment to maintain their function.

A process called "homing" allows HSPCs to anchor in their niches in order to expand and differentiate. Unique niche microenvironments, composed of various blood vessels and other niche components, including stromal cells, regulate this process.

To study the detailed architecture of the microenvironment and the regulation mechanism of homing, Prof. PAN Weijun's group at the Shanghai Institute of Nutrition and Health of Chinese Academy of Sciences used a zebrafish model to analyze the entire dynamic process of HSPC homing in vivo. The results entitled "VCAM-1+ macrophages guide the homing of HSPCs to a vascular niche" was published in Nature on Nov. 19, 2018.

By using a combination of advanced live imaging and a cell labeling-tracing system, researchers performed a high-resolution analysis of HSPC homing in zebrafish caudal hematopoietic tissue (CHT, equivalent to the fetal liver in mammals).

Compared to itga4 mutants with homing defects, successful HSPC retention was defined in CHT as the lodgement of HSPCs for more than 30 minutes.

The researchers also found that HSPCs preferred to stay at retention "hotspots" associated with venous capillaries, which are largely localized at the venous capillary confluence points connected to the caudal vein plexus.

Further study showed that VCAM-1+ macrophages patrolling the inner surface of the venous plexus interact with HSPCs in an ITGA4-dependent manner and direct HSPC retention.

These cells, named "usher cells," guide HSCP homing to two types of vascular niches. Usher cells, together with endothelial cells, help HSPC homing through distinct mechanisms.

This study dissects the temporal-spatial rules of HSPC retention, provides new insights into the mechanism for HSPC homing, and reveals the essential role of a VCAM-1+ macrophage population with patrolling behavior in HSPC retention.



HSPC 'Seeds' reveal VCAM-1+ macrophage role in homing process | EurekAlert! Science News

Dantong Li, Wenzhi Xue, Mei Li, Mei Dong, Jianwei Wang, Xianda Wang, Xiyue Li, Kai Chen, Wenjuan Zhang, Shuang Wu, Yingqi Zhang, Lei Gao, Yujie Chen, Jianfeng Chen, Bo O. Zhou, Yi Zhou, Xuebiao Yao, Lin Li, Dianqing Wu, Weijun Pan. VCAM-1+ macrophages guide the homing of HSPCs to a vascular niche. Nature (2018). DOI: 10.1038/s41586-018-0709-7​

Shanghai team makes stem cell progress
By Zhou Wenting in Shanghai | China Daily | Updated: 2018-11-21 08:59

Scientists in Shanghai say they have uncovered how hematopoietic stem cells find a suitable microenvironment in vivo - observation of live isolated cells - offering insights into improving the efficiency of hematopoietic stem cell transplantation.

By using a combination of advanced live imaging and a cell labeling and tracing system, the scientists observed the complete dynamic process of neonatal hematopoietic stem cells finding their appropriate microenvironment in hematopoietic tissues, allowing them to self-renew or produce all types of blood cells.

"It's like there are some seats in the caudal hematopoietic tissue. The stem cells can only function after finding these seats. We call it 'homing'," said Li Mei, a researcher on the team from the Chinese Academy of Sciences' Shanghai Institute of Nutrition and Health.

The lack of understanding of how such stem cells find a suitable microenvironment has restricted the clinical development of hematopoietic stem cell transplants, a promising approach to treating major diseases, such as blood diseases, immune diseases and cancers, researchers said.

"In current transplantation, when millions of cells are transplanted into a patient's bone marrow, only several thousand end up playing their roles," said Jing Naihe, a principal investigator at the CAS Center for Excellence in Molecular Cell Science.

"It's exactly because the process remained unknown how such stem cells anchor in niches in order to expand and differentiate that doctors needed to collect a large amount of stem cells from donors, which is also a kind of waste," he said.

The researchers used zebrafish, a vertebrate species whose embryos are transparent so the procedure of "homing" can be observed. They found a type of cell that can identify hematopoietic stem cells in a number of blood cells and direct them into specific vascular structures to give their functions full play.

"We call such cells 'usher cells', as they function very much like the staff at the entrance of the theater and direct audience members to their seats with a flashlight," said Pan Weijun, the team's lead researcher.

A paper on their research over six years was published on the website of British scientific journal Nature on Tuesday.

Natalie Le Bot, a senior editor of Nature, said that understanding the process of homing in vivo and the specific cells involved is key to improving transplantation success.

Chen Tong, director of hematology at Huashan Hospital Affiliated to Fudan University, said: "The research results indicated that when doctors perform hematopoietic stem cell transplantations in the future, we may be able to guide the homing of hematopoietic stem cells, which could greatly improve the success rate of such transplantations."

 

[JSCh]

NEWS Q&A | 23 NOVEMBER 2018
Inside the plans for Chinese mega-collider that will dwarf the LHC
Physicist Wang Yifang, the mastermind behind the project, gives Nature an update on the ambitious project.

Wang Yifang directs the Institute of High Energy Physics in Beijing.Credit: Tim Kramer/Ruhr-Universität Bochum​

Physicists at Beijing’s Institute of High Energy Physics (IHEP) are are designing the world's biggest particle smasher. If built, the 100-kilometre-circumference facility would dwarf the 27-kilometre Large Hadron Collider (LHC) at CERN, Europe’s particle-physics laboratory near Geneva, Switzerland — and would cost around half the price.

The ambitious 30-billion-yuan (US$4.3-billion) facility, known as the Circular Electron–Positron Collider (CEPC), is the brainchild of IHEP’s director, Wang Yifang. He has spearheaded the project since the discovery of the elementary particle called the Higgs boson at the LHC in 2012.

The CEPC will produce Higgs bosons by smashing together electrons and their antimatter counterparts, positrons. Because these are fundamental particles, their collisions are cleaner and easier to decipher than the LHC’s proton–proton collisions, so once the Chinese facility opens, in about 2030, it will allow physicists to study the mysterious particle and its decay in exquisite detail.

Last week, IHEP published a milestone report outlining the blueprint for the collider. Initial funding for research and development has come from the Chinese government, but the design is the work of an international collaboration of physicists and the team hopes to garner funding from around the world. (Researchers behind a long-planned rival ‘Higgs factory’ known as the International Linear Collider expect to learn by the end of this year whether Japan will stump up the cash to host it.)

The blueprints reveal that the Chinese collider would run in a circle 100 metres underground, at a location yet to be decided, and host two detectors. At the end of its ten-year lifespan, the electron–positron machine could be upgraded to collide protons at energies seven times those of the LHC at its peak. Ahead of the report’s publication, Nature spoke to Wang about the project.

After six years of design work, an international board of experts says the collider is ready to proceed. Construction could begin as early as 2022. What happens now?[/B][/B][/SIZE]
We are working on the technology research and development (R&D) at the moment. No one has ever built a machine this large before, and we want to minimize the cost. Its specifications are different from those of any other machine in the world in the past, and we have to prove that it is feasible.

Two years ago, the collider’s international advisory committee said the project lacked international involvement. Has there been progress on that front?
It has not significantly changed, because international participation is still limited by the financial commitment of the international partners. They are all interested, but they need to get endorsement from their funding agencies. They are waiting to hear the Chinese government’s position on whether to fund it, and that decision depends on the outcome of the R&D. But CERN is working on a new European strategy for particle physics, so we hope that this time the CEPC can be included. A similar process will happen in the United States, probably in the next year or 2020. We hope it will be included in both.

A Chinese collider operating in the 2030s would be in direct competition with CERN’s own plans to build a successor to the LHC. Do you think there is a need for more than one mega-collider?
It’s too early to say this is a competition. I think it’s good to have different proposals and to explore the advantages and disadvantages of each proposal thoroughly. Then we can see which one is more feasible, and the community will decide.

Do you think the international community would accept China becoming the global centre of high-energy physics, given that the country lacks free access to the Internet and has significant government controls?
Such a centre would help China to become more internationalized, more open towards the world. And it is going to bring more resources to the scientific community. People at the very beginning may feel that it is not as convenient compared to Switzerland. But we hope that the collider would be a good thing, at least for the Chinese. Also, I don’t think this is going to be the only centre in the world. Historically, we always have had many particle-physics centres, although now we have fewer and fewer. But I really hope we’re not going to be the only one. If you have no competition in a field, at some point you’re going to die.

China is undergoing something of a boom in accelerator facilities at the moment. Tell me about some of those plans.
The spallation neutron source in Dongguan is now operating. It is small but good enough. IHEP is also planning a 1.4-kilometre-circumference light source to be built in Huairou, northern Beijing, at a cost of 4.8 billion yuan. This is a circular electron accelerator that can generate synchrotron radiation — X-rays with extremely high intensity. These are useful for almost every research discipline, including materials science, chemistry, biology, environmental science, geology and medicine. We believe the government is going to give its final approval for the project by the beginning of next year, and then we can start construction. We think it would be a world-leading machine. Most light sources are upgrades from existing machines, so they are limited. We can use the best configurations, the best technologies, without constraints.

The institute is also pitching to fly an experiment — a detector measuring highly energetic particles known as cosmic rays — on China’s crewed space station, set to launch in 2020. What will it do and how will it improve on existing experiments?
We want to know where cosmic rays come from, and how they get such high energy. Answers to these questions will help us to understand the Universe. We would also like to use it to search for new particles, such as dark matter, which cannot yet be generated by accelerators on Earth. One of today’s best experiments for studying this is the Alpha Magnetic Spectrometer (AMS) on the International Space Station, which has not yet seen clear evidence of dark matter. That means we need experiments that can detect more particles, and at higher energies. The High Energy Cosmic Radiation Detection experiment will be able to study particles roughly ten times the energy of the AMS, and measure their energies with better resolution. We’ve almost finished our design and we’re now trying to get support from the Chinese government. We’re probably talking about US$200 million to $300 million for the detector. It’s on the list of candidates for possible projects for the future Chinese space station. We have to wait, but I am optimistic.

Do you think high levels of science funding in China will continue?
The government is certainly interested in supporting science. They hope every penny they invest is worth something, and sometimes we in high-energy physics disappoint them — we’re not able to immediately generate results.

Has the political situation between the United States and China affected the relationship between the two countries’ scientists?
It’s difficult at the moment. If we organize a conference in China, people from US universities can come freely, but people working at US national laboratories say they can’t get permission. Also, going the other way, it’s very hard for Chinese scientists to get an invitation letter to those laboratories in the United States. I really hope this is just temporary and politicians can realize that the exchange of science and collaboration in science is mutually beneficial.

doi: 10.1038/d41586-018-07492-w


Inside the plans for Chinese mega-collider that will dwarf the LHC | Nature

 

[JSCh]

Ready for its close-up—a bacterium's electron transport pathway
November 5, 2018 by Thamarasee Jeewandara, Phys.org

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Respiration in Actinomycetes and overall architecture of the Mycobacterial respiratory machine CIII2CIV2SOD2. A) The respiratory electron transfer chain in Actinomycetes (left) and the 5 major prokaryotic cytochrome c pathway variants with …more

In a recent study conducted by Hongri Gong and colleagues, a respiratory supercomplex was isolated from the bacterium Mycobacterium smegmatis, and its structure was visualized at a resolution of 3.5 Å using cryo-electron microscopy (cryo-EM). The bacterium is a close relative to M. tuberculosis and a popular model used to study many other bacterial species. The detailed structure revealed how electrons were transferred in the cell in a process hitherto unseen.



Read more at: https://phys.org/news/2018-11-ready-close-upa-bacterium-electron-pathway.html#jCp

Hongri Gong, Jun Li, Ao Xu, Yanting Tang, Wenxin Ji, Ruogu Gao, Shuhui Wang, Lu Yu, Changlin Tian, Jingwen Li, Hsin-Yung Yen, Sin Man Lam, Guanghou Shui, Xiuna Yang, Yuna Sun, Xuemei Li, Minze Jia, Cheng Yang, Biao Jiang, Zhiyong Lou, Carol V. Robinson, Luet-Lok Wong, Luke W. Guddat, Fei Sun, Quan Wang, Zihe Rao. An electron transfer path connects subunits of a mycobacterial respiratory supercomplex. Science (2018). DOI: 10.1126/science.aat8923​

 

[JSCh]

Scientists Uncover Mechanism Safeguarding Unique Epigenome of Oocytes and Maternal Fertility
Nov 29, 2018

In mammals, females have a limited supply of oocytes. These oocytes also have a unique epigenome with approximately half the DNA methylation of sperm and most terminally differentiated somatic cells. Until recently, regulators of this unique DNA methylation pattern and its functional significance were unknown.

Now, a novel DNA methylation regulator Stella, whose ectopic overexpression in somatic cells led to global DNA demethylation through disrupting the function of the DNA methylation regulator UHRF1, has been identified.

In a recent study published online ahead of print in Nature, a joint research group led by Dr. ZHU Bing from the Institute of Biophysics of the Chinese Academy of Sciences reveals that Stella sequestered UHRF1 from the nucleus through an active nuclear export process, and the dysregulation of UHRF1 by loss of Stella resulted in an accumulation of aberrant DNA methylation during postnatal oogenesis.

These findings show the first regulatory factor found to safeguard the unique methylation status of the oocyte genome.

Since Stella is highly expressed in oocytes, the researchers focused on the in vivo function of Stella during oogenesis.

Earlier studies revealed that Stella-null oocytes were incapable of supporting the development of preimplantation embryos. This study shows preferential hypermethylation at the transcriptionally inert regions of Stella null oocytes. These aberrant promoters of hypermethylation on the maternal allele severely affected zygotic genome activation and development of the preimplantation embryo.

Interestingly, a maternal genome lacking DNA methylation had been reported to not affect preimplantation embryo development, while this study suggests that keeping a uniquely hypomethylated oocyte genome is vital.

Moreover, researchers found that DNMT1, generally considered to be a maintenance DNA methyltransferase, which is only active on hemi-methylated DNA in vivo, is the major DNA methyltransferase responsible for the aberrant DNA methylation in Stella-deficient oocytes and unambiguously proves the de novo methylation activity of DNMT1 in vivo.

This discovery rewrites the textbook classification of DNA methyltransferases. Also, it sheds light on a functional role of DNMT1 in post-mitotic cells, which may help to reveal a role for DNMT1 in ageing.

The study was supported by the China National Science Foundation, the Chinese Ministry of Science and Technology, the Chinese Academy of Sciences, and the Science and Technology Commission of Shanghai, among others.

Stella sequesters UHRF1 to safeguard the unique methylome of oocytes. (Image by Dr. ZHU Bing’s group)


Scientists Uncover Mechanism Safeguarding Unique Epigenome of Oocytes and Maternal Fertility---Chinese Academy of Sciences

Yingfeng Li, Zhuqiang Zhang, Jiayu Chen, Wenqiang Liu, Weiyi Lai, Baodong Liu, Xiang Li, Liping Liu, Shaohua Xu, Qiang Dong, Mingzhu Wang, Xiaoya Duan, Jiajun Tan, Yong Zheng, Pumin Zhang, Guoping Fan, Jiemin Wong, Guo-Liang Xu, Zhigao Wang, Hailin Wang, Shaorong Gao, Bing Zhu. Stella safeguards the oocyte methylome by preventing de novo methylation mediated by DNMT1. Nature (2018). DOI: 10.1038/s41586-018-0751-5​

 

[JSCh]

Spider moms spotted nursing their offspring with milk
By Elizabeth Pennisi
Nov. 29, 2018 , 2:00 PM

On a summer night in 2017, Chen Zhanqi made a curious find in his lab in China’s Yunnan province. In an artificial nest, he spotted a juvenile jumping spider attached to its mother in a way that reminded him of a baby mammal sucking its mother’s teats. On closer inspection, the spider mom really seemed to be doting on her young, he says. “She had to invest so much in caring for the baby.”

Further study by Chen and Quan Rui-Chang, behavioral ecologists at the Chinese Academy of Sciences’s Center for Integrative Conservation in Menglunzhen, confirmed the jumping spider females were indeed producing milk for their offspring—and that they continued to do so even after the spiderlings became teenagers, they and colleagues report today.

Providing milk and long-term care together is virtually unheard of in insects and other invertebrates. And with the exception of mammals, it’s not even that common among vertebrates. As such, the results “help increase our understanding of the evolutionary origins of complex forms of parental care,” says Nick Royle, a behavioral ecologist at the University of Exeter in the United Kingdom who was not involved with the work. They suggest prolonged mothering may not require the complex brain power that researchers have assumed, he says.

Females of this jumping spider species (Toxeus magnus) lay between two and 36 eggs at a time. As soon as the eggs hatch, the mother begins to deposit tiny milky droplets around the nest, Chen and colleagues observed in the lab. When the team members analyzed the liquid, they discovered it contained four times the protein of cow’s milk, as well as fat and sugar.

In their first couple of days, the baby spiders sipped droplets of this spider milk around the nest, the researchers observed. But soon they began to line up at the entrance of the mother’s birth canal to suckle. At 20 days, they began to hunt outside the nest, but they still supplemented their diet with mother’s milk until they were sexually mature—another 20 days.

When Chen painted over the mothers’ birth canals to cut off the milk supply, spiders younger than 20 days all died. When he removed the mother from the nest, older spiders grew more slowly, left the nest sooner, and were more likely to die before adulthood, he and his colleagues report today in Science. Other spiders may hang around their young for a few days but rarely feed them.

The “milk” may be liquified eggs that are passed out of the birth canal prematurely, Quan says. Some amphibians and other invertebrates lay similar “trophic eggs” for offspring to eat, he notes, although only when those offspring are really young. Cockroaches also produce “milk,” but that nourishment is simply absorbed passively through the eggshell of their embryos and is not part of the hatched roachlings’ diets.

The long-lasting parental care the team observed in jumping spiders mostly exists only in very few long-lived social vertebrates, such as humans and elephants, Quan says. “The extended maternal care indicates that invertebrates have also evolved [this] ability.”

Rosemary Gillespie, an evolutionary ecologist at the University of California, Berkeley, notes some other spider species also seem to provide for their young. One study in the 1990s observed that spiderlings of the funnel web spider Coelotes ate clear yellow drops of liquid or brownish clusters deposited on the web. Mothers of another spider called Amaurobius lay “naked” egg sacs that spiderlings immediately devour.

Such care often signals a greater than usual offspring need, Royle says. For example, if there’s a chance there will be no food for newborns, or that young spiders are likely to be eaten by other predators before they have a chance to grow up and reproduce, then it can make sense for a mother to become a “helicopter” parent, he explains. Because this behavior taxes the mother, he adds, it likely only evolves in extreme situations.


Spider moms spotted nursing their offspring with milk | Science | AAAS

Zhanqi Chen, Richard T. Corlett, Xiaoguo Jiao, Sheng-Jie Liu, Tristan Charles-Dominique, Shichang Zhang, Huan Li, Ren Lai, Chengbo Long, Rui-Chang Quan. Prolonged milk provisioning in a jumping spider. Science (2018). DOI: 10.1126/science.aat3692​

 

[JSCh]

PUBLIC RELEASE: 14-NOV-2018
When electric fields make spins swirl
First example of ferroelectrically tunable skyrmions brings new hope for next-generation magnetic memory devices

INSTITUTE FOR BASIC SCIENCE

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This study measured skyrmions in an ultra-thin material made of a ferromagnetic layer of strontium ruthenate (SrRuO3), overlaid with a ferroelectric layer of barium titanate (BaTiO3) and grown on a strontium titanate (SrTiO3) substrate. BaTiO3 is ferroelectric, meaning that it has a switchable and permanent electric polarization (), while SrRuO3 is ferromagnetic below 160 Kelvin (-113 Celsius). At the BaTiO3/SrRuO3 interface, the BaTiO3 ferroelectric polarization swirls the spins in SrRuO3, generating skyrmions. If the researchers flip the direction of polarization in BaTiO3, the density of the skyrmions changes. CREDIT: IBS

We are reaching the limits of silicon capabilities in terms of data storage density and speed of memory devices. One of the potential next-generation data storage elements is the magnetic skyrmion. A team at the Center for Correlated Electron Systems, within the Institute for Basic Science (IBS, South Korea), in collaboration with the University of Science and Technology of China, have reported the discovery of small and ferroelectrically tunable skyrmions. Published in Nature Materials, this work introduces new compelling advantages that bring skyrmion research a step closer to application.

It is envisioned that storing memory on skyrmions - stable magnetic perturbations of whirling spins (magnetic moments) - would be faster to read and write, consume less energy, and generate less heat than the currently used magnetic tunnel junctions. In future memory and logic devices, 1 and 0 bits would correspond to the existence and non-existence of a magnetic skyrmion, respectively. Although numerous skyrmion systems have been discovered in laboratories, it is still very challenging to produce controllable, nanometer-sized skyrmions for our technology needs.

In this study, the researchers found out that skyrmions with a diameter smaller than 100 nanometers spontaneously form in ultrathin material, consisting of a layer of barium titanate (BaTiO3) and a layer of strontium ruthenate (SrRuO3). Below 160 Kelvin (-113 Celsius), SrRuO3 is ferromagnetic, meaning that its spins are aligned uniformly in a parallel fashion. When the two layers are overlaid, however, a special magnetic interaction swirls SrRuO3's spins, generating magnetic skyrmions. Such peculiar magnetic structure was detected below 80 Kelvin (-193 Celsius) by using magnetic force microscopy and Hall measurements.

In addition, by manipulating the ferroelectric polarization of the BaTiO3 layer, the team was able to change the skyrmions' density and thermodynamic stability. The modulation is non-volatile (it persists when the power is turned off), reversible, and nanoscale.

"Magnetic skyrmions and ferroelectricity are two important research topics in condensed matter physics. They are usually studied separately, but we brought them together," explains Lingfei Wang, first author of the study. "This correlation provides an ideal opportunity to integrate the high tunability of well-established ferroelectric devices with the superior advantages of skyrmions into next-generation memory and logic devices."


When electric fields make spins swirl | EurekAlert! Science News

 

[JSCh]

City scientists in cancer breakthrough
By Li Qian | 00:06 UTC+8 November 30, 2018

Local scientists have found a new way to break the defense mechanism of malignant tumor cells, providing a possible new way to fight cancer.

Xu Chenqi and his research team from the Chinese Academy of Sciences’ Shanghai Institute of Biochemistry and Cell Biology have found a new way that T cells interact with tumors, according to a report published in the journal Nature yesterday.

T cells, a type of white blood cell, can recognize and decompose tumor cells. Tumor cells, however, fight back. They are able to interact with a protein (PD-1) on the surface of the T cells and suppress the cells’ function.

The team found an enzyme (FBXO38) helps maintain the integrity of the T cell. The enzyme it is not very active in the tumor microenvironment, and its performance needs to be boosted. Cancer drug IL-2 can do exactly that, reinvigorating T cells, the research showed.

IL-2 was approved by Food and Drug Administration in US in 1995 as a treatment for skin and kidney cancers, but it is not widely used because of some extreme side effects.

Researchers will now explore other ways to use IL-2 in combination with other drugs.

“There needs more research of the fundamental questions of PD-1 biology,” Xu said.

Xu’s team started to study T cells when he joined the CAS from Harvard Medical School in 2009. In 2016, results of their research into the function of T cells were also published in Nature.

Xiangbo Meng, Xiwei Liu, Xingdong Guo, Shutan Jiang, Tingting Chen, Zhiqiang Hu, Haifeng Liu, Yibing Bai, Manman Xue, Ronggui Hu, Shao-cong Sun, Xiaolong Liu, Penghui Zhou, Xiaowu Huang, Lai Wei, Wei Yang, Chenqi Xu. FBXO38 mediates PD-1 ubiquitination and regulates anti-tumour immunity of T cells. Nature (2018). DOI: 10.1038/s41586-018-0756-0​

 

[yusheng]

The First and Highest Resolution UV Super Resolution Lithography Equipment in the World

http://english.ioe.cas.cn/ns/es/201811/t20181130_201684.html

SKLOTNM： the State Key Laboratory of Optical Technologies on Nano-fabrication and Micro-engineering (SKLOTNM), Institute of Optics and Electronics, Chinese Academy of Sciences

On the day of NOV 29th, IOE announced that it has developed the first UV super resolution lithography equipment in the world. As a result, the major engineering obstacles limiting China's development in chips, nanocomponents and optical instruments will be excluded. “We no longer fear a foreign technical blockade because we have full intellectual ownership of the new technique,” said Hu Song, the senior researcher of IOE and deputy chief designer of this project.

The new machine, which scientists began building in 2012, can etch circuitry patterns less than 22 nanometers using ultraviolet light. Combined with other techniques, it can be used in the future to create chips of around 10 nanometers.

Hu said that the machine can also be used to make small components for applications such as sensors, detectors and biochips. It is already being used by several institutions including Sichuan University and the University of Electronic Science and Technology of China. However, the new machine's production capability is still small, hence it is still limited to producing key components for research.

Hu indicates that the team will focus its efforts on increasing the machine's productivity to industrial scale in future. He pointed out that there are still substantial gaps in the microengineering sector between China and developed countries, but China is catching up fast.

【新华社】“超分辨光刻装备项目”通过国家验收 可加工22纳米芯片
作者：　发布时间：2018-11-30　阅读次数：
　　新华社成都11月29日电（记者董瑞丰、吴晓颖）国家重大科研装备研制项目“超分辨光刻装备研制”29日通过验收。该光刻机由中国科学院光电技术研究所研制，光刻分辨力达到22纳米，结合双重曝光技术后，未来还可用于制造10纳米级别的芯片。

　　中科院理化技术研究所许祖彦院士等验收组专家一致表示，该光刻机在365纳米光源波长下，单次曝光最高线宽分辨力达到22纳米。项目在原理上突破分辨力衍射极限，建立了一条高分辨、大面积的纳米光刻装备研发新路线，绕过国外相关知识产权壁垒。

　　光刻机是制造芯片的核心装备，我国在这一领域长期落后。它采用类似照片冲印的技术，把母版上的精细图形通过曝光转移至硅片上，一般来说，光刻分辨力越高，加工的芯片集成度也就越高。但传统光刻技术由于受到光学衍射效应的影响，分辨力进一步提高受到很大限制。

　　为获得更高分辨力，传统上采用缩短光波、增加成像系统数值孔径等技术路径来改进光刻机，但技术难度极高，装备成本也极高。

　　项目副总设计师胡松介绍，中科院光电所此次通过验收的表面等离子体超分辨光刻装备，打破了传统路线格局，形成一条全新的纳米光学光刻技术路线，具有完全自主知识产权，为超材料/超表面、第三代光学器件、广义芯片等变革性领域的跨越式发展提供了制造工具。

　　据了解，这种超分辨光刻装备制造的相关器件已在中国航天科技集团公司第八研究院、电子科技大学、四川大学华西医院、中科院微系统所等多家科研院所和高校的重大研究任务中得到应用。（完）

分析，摘自：http://www.hongdezk.com/26521.html

我国目前的芯片工艺还在14纳米，世界最顶尖的三星、台积电等已能量产7纳米芯片，正在研究3纳米技术。我们落后世界最尖端二三代，时间上相差3~5年。

新研制的这台光刻机，可用于制造10纳米以下的芯片，如果能够投入商用，实现量产，这就让我们追上了国际顶尖，与它们保持了一致水平。

从长远来看，还远不限于此，这台光刻机最大的亮点不在于它追上了国际水平，能制造10纳米以下级别的芯片，而在于它使用的新技术。

我们制造光刻机，一种是像ASML那样使用传统技术，再沿着它的老路走一遍；二是另辟蹊径，实现弯道超车。

光刻机技术，它类似于相片冲印，是将一个巨大的电路设计图缩印到介质上，然后芯片就这样出来了，这个过程中，光刻精度越高，性能就越好，体积也将更小。

ASML使用的传统技术中，有一个天然缺陷，那就是精度受激光“衍射极限”的限制，最终的分辨率取决于波长、数值孔径等因素。

为了提高精度，ASML采用的办法就是使用更短的波长（近紫外-深紫外-极紫外）、增大数值孔径（更复杂的物镜、液体浸没），但这样的办法，越前进，变得越困难，成本也急剧升高。

我们这台光刻机则采用了完全不同的方法，那就是使用“表面等离子体”光刻技术。

其原理是：在一定条件下，物体表面会产生一种特殊电磁波，这种电磁波便是“表面等离子体”。这种特殊电波虽然由其它电波所激发，但其波长会被大大压缩，而且压缩比例取决于材料的电磁性质等参数。

这就从根本上突破了光的“衍射极限”，意味着未来我们的在光刻机、芯片生产上不仅仅是追上国际顶尖，还有可能处于领先水平。

 

[JSCh]

Researchers use optimized single-cell multi-omics sequencing to better understand colon cancer tumor heterogeneity
November 30, 2018 by Bob Yirka, Medical Xpress

Cancer — Histopathologic image of colonic carcinoid. Credit: Wikipedia/CC BY-SA 3.0​

A team of researchers affiliated with several institutions in China has found that using optimized single-cell multi-omics sequencing better reveals colon cancer tumor heterogeneity. In their paper published in the journal Science, the group describes their unique approach to understanding colorectal cancer progression.

The researchers note that most genetic studies of colorectal cancer progression involve looking at gene expression. They suggest that more study is needed to learn how colorectal tumors metastasize. To that end, they have developed a sequencing method that allows for analyzing copy number variants, methylation and gene expression simultaneously in individual cells—the method combines single-cell sequencing data with information from chromosome conformation, epigenetic data and other characteristics of tumor cells.

This work is the next step in a long-term effort to truly understand the mechanics of metastases, particularly in colorectal tumors. Two years ago, the team published a report on their work involving a single-cell triple omics sequencing technique they had developed called sc Trioseq by which they gathered information from gene expression, methylation at CpG sites and copy number alterations from 25 cells obtained from cancer patients.

In the next stage, the researchers raised the number of cells to 1,900 and improved the efficiency of the detection method. The study consisted of collecting cell samples from 12 patients, 10 of whom provided both primary and metastatic data and analyzing them. Using cell data from both sources allowed the researchers to isolate and identify genetic lineages that had developed from mutations for each patient. They used methylation data and copy number information to identify those lineages, allowing them to track the evolutionary changes they went through as they moved from primary tumor cells to metastatic cells.

The team reports that methylation was consistent among the cells within the same genetic lineage but differed when compared to other lineages—and it was also different from non-tumorous cells just next to the tumor. They also found that six chromosomes showed greater levels of demethylation than did others, three of which had recurrent chromosomal changes. They conclude by suggesting that single cell multi-omics sequencing offers the best opportunity for learning more about tumor progression and the spread of cancer.



Researchers use optimized single-cell multi-omics sequencing to better understand colon cancer tumor heterogeneity | Medical Xpress

Shuhui Bian, Yu Hou, Xin Zhou, Xianlong Li, Jun Yong, Yicheng Wang, Wendong Wang, Jia Yan, Boqiang Hu, Hongshan Guo, Jilian Wang, Shuai Gao, Yunuo Mao, Ji Dong, Ping Zhu, Dianrong Xiu, Liying Yan, Lu Wen, Jie Qiao, Fuchou Tang, Wei Fu. Single-cell multiomics sequencing and analyses of human colorectal cancer. Science (2018). DOI: 10.1126/science.aao3791​