China Science & Technology Forum

[JSCh]

PUBLIC RELEASE: 18-OCT-2018
Scientists discover first high-temperature single-molecule magnet
UNIVERSITY OF SUSSEX

​

Molecular structure of the high-temperature single-molecule magnet. CREDIT: Richard Layfield

A team of scientists led by Professor Richard Layfield at the University of Sussex has published breakthrough research in molecule-based magnetic information storage materials.

The group at the University of Sussex, working with collaborators at Sun-Yat Sen University in China and the University of Jyväskylä in Finland, report a new single-molecule magnet (SMM) - a type of material that retains magnetic information up to a characteristic blocking temperature.

Writing in the journal Science, Professor Layfield and his co-authors explain how they successfully designed and synthesized the first SMM with a blocking temperature above 77 K, the boiling point of liquid nitrogen, which is both cheap and readily available.

Previously, it was only possible to synthesize SMMs with blocking temperatures reachable by cooling with expensive and scarce liquid helium.

Professor of Chemistry, Richard Layfield, said: "Single-molecule magnets have been firmly stuck in the liquid-helium temperature regime for over a quarter of a century. Having previously proposed a blueprint for the molecular structure of a high-temperature SMM, we have now refined our design strategy to a level that allows access to the first such material.

"Our new result is a milestone that overcomes a major obstacle to developing new molecular information storage materials and we are excited about the prospects for advancing the field even further."

SMMs are molecules capable of remembering the direction of a magnetic field that has been applied to them over relatively long periods of time once the magnetic field is switched off.

As such, one can "write" information into molecules leading SMMs to have various potential applications, such as high-density digital storage media and as parts of microprocessors in quantum computers. Practical applications have, however, been greatly hindered by the fact that SMMs are operational only at extremely low temperatures. Their intrinsic memory properties often vanish if they are heated a few degrees above absolute zero (-273°C), meaning SMMs can be only studied under laboratory conditions by cooling them with liquid helium.

The discovery of the first high-temperature SMM means developments could be made in the future to massively increase the storage capacity of hard disks without increasing their physical size.


Scientists discover first high-temperature single-molecule magnet | EurekAlert! Science News

Fu-Sheng Guo, Benjamin M. Day, Yan-Cong Chen, Ming-Liang Tong, Akseli Mansikkamäki & Richard A. Layfield. Magnetic hysteresis up to 80 kelvin in a dysprosium metallocene single-molecule magnet. Science (2018). DOI: 10.1126/science.aav0652​

 

[JSCh]

EDITORIAL
Network for safe and secure labs | Science
James W. Le Duc, Zhiming Yuan

Science 19 Oct 2018:
Vol. 362, Issue 6412, pp. 267
DOI: 10.1126/science.aav7120

The current outbreak of Ebola virus in the Democratic Republic of the Congo is a reminder that dangerous diseases exist in many corners of the world and that they can cause substantial human suffering and financial devastation locally and internationally. In response, institutions and nations are constructing maximum biocontainment laboratories (MCLs) to address these threats. MCLs operate at the highest level of biological containment to diagnose, perform research on, and validate cures for life-threatening diseases like Ebola. There are more than 50 MCLs that are operational, under construction, or in advanced planning around the world. The global proliferation of these facilities raises questions about how to ensure their safe and secure operations while enhancing their contributions to science and global health. One solution is to establish an MCL network that enables the sharing of best practices, collaboration, transparency, and exchange of specimens and technology.

“These labs handle the world's most dangerous pathogens…”

A multitude of challenges are associated with MCLs. Even at the idea stage, a serious issue is the objection of local communities to the construction of an MCL in their neighborhood. Several MCL operations were delayed or never realized because of public concern. Gaining community trust and support is therefore vital to planning and operating MCLs, so a network of such labs would be valuable for sharing experiences and providing guidance in these situations.

Besides the millions of dollars that it costs to build a modern MCL, there are annual operations—maintenance, utility, and security—that can amount to 5 to 10% of the construction costs. Moreover, there is a need for experienced guidance and qualified oversight to ensure that an MCL is built and operated safely and securely. Yet, few such resources exist, and available training opportunities are inconsistent and often costly. An MCL network could fill the personnel pipeline more efficiently by connecting experienced personnel and professional societies to develop standards for globally accepted training and create mentoring opportunities.

Importantly, MCLs must share a culture of responsibility. These labs handle the world's most dangerous pathogens known, and there must be safeguards to prevent theft or misuse. At the same time, security must be balanced against mechanisms that support collaboration, including specimen sharing. Again, by working together through an MCL network to develop standards and guidelines, a culture of responsibility could be fortified.

We direct a newly constructed MCL in Wuhan, China (Z.Y.), and an established MCL in the United States (J.W.L.), in Galveston, Texas. In preparation for the opening of the new China MCL, we engaged in short- and long-term personnel exchanges focused on biosafety training, building operations and maintenance, and collaborative scientific investigations in biocontainment. We succeeded in transferring proven best practices to the new Wuhan facility. Both labs recently signed formal cooperative agreements that will streamline future scientific and operational collaborations on dangerous pathogens, although funding for research and the logistics of exchanging specimens are challenges that we have yet to solve. Ours is a promising first step in MCL partnerships; however, wider national, regional, and international cooperation is needed. We benefited from meetings jointly sponsored by the U.S. National Academy of Sciences and the Chinese National Academy of Sciences, and from World Health Organization initiatives, but stakeholders are not limited to human and animal health. Our partnership still requires input from foundations and governmental agencies that are involved in security, commerce, and transportation, as well as from the commercial sector.

Not every country requires an MCL, but every country can benefit from the collaborative operation of these labs. We encourage existing MCLs to convene a forum that brings together all stakeholders to conceive of an MCL network so that these critical labs can tackle urgent global health needs safely, securely, and productively.

 

[JSCh]

Westlake University a model of reform
By MA ZHENHUAN | China Daily | Updated: 2018-10-22 07:41

Shi Yigong, president of Westlake University (left), joins Nobel laureate Yang Zhenning (second from left), Zhejiang Governor Yuan Jiajun (second from right) and Han Qide, former vice-chairman of the national political advisory body (center), at the founding ceremony for Westlake University on Saturday in Hangzhou, Zhejiang province. CHINA DAILY

Private college in Zhejiang province will set pace for innovation, ministry says

The founding of Westlake University, China's first private university aimed at cultivating high-level talent in advanced technology, marks a significant step in efforts to reform the higher-education sector and foster innovation, the Ministry of Education said.

In a congratulatory letter sent for a founding ceremony on Saturday, the ministry said it hopes the university will focus on basic advanced scientific research and become a top higher-education institution with Chinese characteristics.

The presidents of more than 50 universities attended the ceremony in Hangzhou, Zhejiang province, along with Nobel laureates Yang Zhenning, James Watson, Jean-Marie Lehn, Brian Kobilka and Fraser Stoddart.

Shi Yigong, president of Westlake University, said the university aspires to become a pioneer in China's higher-education reform and a cradle of innovative talent in advanced science and technology.

"We want to build the university into a truly international higher-education institution," he said.

Initiated by a team of seven top Chinese academics, including Shi, a Princeton University-trained molecular biologist, the university won approval from the Education Ministry in February.

Expectations have been running high, as it will be China's first private university to grant doctorates. One aim is to rival international counterparts such as Rockefeller University and the California Institute of Technology, both in the United States.

Construction of the main Yungu campus, in Hangzhou's Xihu district, began in April. The first phase of construction covers 450,000 square meters and is expected to be completed by the end of 2021.

The university launched a global recruitment campaign for academics in July 2016 and has received more than 5,000 applications. So far, it has recruited 68 academics from 13 countries to teach physics, chemistry, engineering, biology and basic medicine, among other subjects.

The first 19 PhD candidates were enrolled in September last year, with a further 120 arriving in August.

"It's a common aspiration for all of us that Westlake University－like Hangzhou's West Lake－will win acclaim at home and abroad, and eventually become one of the world's leading universities," Che Jun, Party secretary of Zhejiang, said at the founding ceremony.

 

[JSCh]

China unveils blueprint for huge underground ‘Higgs factory’
06 Sep 2018 Michael Banks

​

Planning ahead: physicists at Beijing's Institute of High Energy Physics are supporting a plan to build a huge 100 km circular collider in China to study the Higgs boson in unprecedented detail. (Courtesy: IHEP)

Scientists in China have released details for a huge particle collider that will produce over a million Higgs bosons in a seven-year period. The conceptual design report for the China Electron Positron Collider (CEPC) calls for a 100 km underground tunnel that would smash together electrons and positrons at energies of 240 GeV. The CEPC would be a successor to the Beijing Electron Positron Collider at the Institute of High Energy Physics (IHEP) in Beijing, which is expected to shut in 2020.

The CEPC, which was first proposed in 2012, is a “Higgs factory” – a facility to measure the precise properties of the Higgs boson, which was discovered at CERN in 2012 by scientists working on the Large Hadron Collider (LHC). An electron-positron machine can make much cleaner measurements than a proton collider like the LHC as its collisions do not produce as much debris. The CEPC will therefore allow the Higgs boson to be studied in unprecedented detail.

A preliminary conceptual design report for the CEPC was originally published in March 2015. That was followed by a progress report in April 2017, but the new 510-page conceptual design report, released this week on the arXivpreprint server, outlines the technical details of the accelerator. A second volume, featuring details of the CEPC detectors, is due to be released soon.

Particle factory
Estimated to cost around $6bn, the “heart” of the CEPC is a double-ring collider in which electron and positron beams will circulate in opposite directions in separate beam pipes. They will then collide at two “interaction points”, which will each contain a particle detector. The report reveals the CEPC will seek to generate over a million Higgs bosons over a seven-year period. The design also calls for the CEPC to operate at 91 GeV for two years to generate a trillion Z bosons as well as run at 160 GeV for a year to produce around 15 million pairs of W+ and W- particles.

Scientists will now build prototypes of key components of the accelerator and plan the manufacturing process required to construct the CEPC. If given the go-ahead by the government, construction of the CEPC could begin in 2022 and be complete by 2030. Following a decade of studying the Higgs, Z and W bosons, it is hoped that developments in magnet technology will be sufficient to begin construction of a proton-proton collider inside the existing tunnel in the early 2040s. This would operate in the range of 70-100 TeV and search for particles beyond the Standard Model of particle physics.

The location of the CEPC has not yet been decided with six locations currently satisfying the “technical requirements”. However, it is thought that the leading site is 300 km east of Beijing at the port city of Qinhuangdao. Speaking to Physics World earlier this year, IHEP director Yifang Wang says that a more detailed investigation of the geological conditions at some of the possible sites is needed before a decision can be made. “We need to know what kind of support from the local government we will receive in terms of, for example, laboratories, living conditions, roads and power supply,” he says.

Analysis: China could win the Higgs factory race

The race is on to build a Higgs factory – a successor to CERN’s Large Hadron Collider. For years it was thought that the International Linear Collider (ILC) was in pole position. The ILC’s five-volume technical design report was published in June 2013, calling for a 30 km-long linear collider that would smash electrons with positrons at around 500 GeV. The Japanese physics community quickly got behind the project expressing their desire to host the machine with a site in the Tōhoku region, about 400 km north of Tokyo, chosen as a potential location.

However, the Japanese government has dragged its feet over deciding to support the project and last year — to make the ILC more palatable — physicists came up with a revised plan, reducing the ILC’s energy to 250 GeV and shortening the length of the tunnel to around 20 km. While physicists hope that the Japanese government will now get behind the facility by the end of the year, there are many other projects vying for funding, no less a major new neutrino facility in Kamioka. It is likely that a decision about the ILC will be kicked further down the road.

There is another design for a linear collider to study the Higgs. The Compact Linear Collider would smash together electron with positron at energies up to 3 TeV, but despite a three-volume conceptual design report being released in 2012, it remains behind the ILC in terms of technical development. That now leaves the door open to China and momentum seems to be on their side. Speaking to Physics World earlier this year, Yifang Wang, head of China’s Institute of High Energy Physics, noted that there was “enormous interest” for the CEPC from funding agencies in the country.

Given the amount of cash that the Chinese government is ploughing into science as well as the technical ability of Chinese scientists and engineers to build world-class facilities, it would be hard to bet against the CEPC being first.​

China unveils blueprint for huge underground ‘Higgs factory’ – Physics World

China to build world’s largest supercollider
By Deng Xiaoci Source:Global Times Published: 2018/10/22 21:38:39

A sketch of the future Circular Electron Positron Collider. Photo: Courtesy of Chinese Academy of Sciences Institute of High Energy Physics

Chinese scientists plan to build the world's most powerful electron collider by 2030, a project that will cost 35 billion yuan ($5.05 billion), the project's leading scientist told the Global Times on Monday.

The location of the project has yet to be decided, Wang Yifang, director of the Chinese Academy of Sciences Institute of High Energy Physics in Beijing, told the Global Times on Monday.

"The collider will have a circumference of 100 kilometers, with a center-mass energy up to 240 giga electron-volts both setting a world record," Wang said. The collider should produce more Higgs boson particles, the essential, inevitable quarry of modern particle physics, He noted.

The conceptual design for the Circular Electron Positron Collider (CEPC) passed international examinations in September, Wang said.

The collider will provide light at a million electron-volt power level, creating the most advanced conditions for research on new materials and nuclear physics, Wang explained.

Scientists from the US, Europe and Japan have participated in designing the project, will work on the building process and conduct research with the collider, Wang said.

In a bid to maximize the project's service life, scientists are mulling upgrading the electron positron collider around 2040 into a proton collider, Wang noted.

By then, the center-mass energy for the CEPC will have reached about 100 tera electron-volts, seven times as powerful as the Large Hadron Collider (LHC) in Switzerland, Wang said.

The Swiss project near Geneva is the world's largest and most powerful particle collider and reportedly the largest machine in the world.

Fears have also mounted over the development of the huge collider. Some Western media said there's a chance the colliders could cause a catastrophe that engulfs space itself.

It was "groundless and with no scientific basis" to speculate that a collider could create a black hole that puts lives at risk, Wang said. "Powerful cosmic rays and nuclei clash daily on Earth at forces a million times stronger than those created in any lab."

"Similar concerns were raised before the LHC began running in Europe and time has proven its safety," he said.

 

[JSCh]

NEWS | 24 OCTOBER 2018
China hides identities of top scientific recruits amidst growing US scrutiny | Nature
Chinese researchers fear that affiliation with the high-status Thousand Talents scheme could make them targets of FBI investigations.

Smriti Mallapaty

​

US congressman Lamar Smith accused China of planting sleeper agents in US universities to steal scientific breakthroughs at an April 2018 hearing.Credit: Scott J. Ferrell/Congressional Quarterly/Getty

China’s flagship science talent recruitment programme, the Thousand Talents Plan, has gone underground amidst intensifying scrutiny by United States government agencies for China's suspected role in the theft of US technologies and intellectual property.

A climate of fear has engulfed Chinese scientists in both countries worried that association with the previously prestigious programme will make them targets of US investigations, including by the Federal Bureau of Investigation (FBI).

Lists of scholars affiliated with the Thousand Talents Plan — a Chinese government scheme to attract Chinese scientists and entrepreneurs back to their homeland — have been removed from government and institutional websites in China.

A memo by a prominent official grant-funding agency, the National Natural Science Foundation of China, circulating on social media instructs interviewers of potential applicants to avoid e-mail correspondence, and not to mention the Thousand Talents Plan when inviting candidates back to the country.

Another widely circulated message on social media, claiming to be from the human resources department of an institution that was not named, urges representatives of fellow HR departments to delete information on their websites related to the Thousand Talents Plan, as “required by the Ministry of Education”. The message asserts that the FBI is investigating researchers involved with the plan.

The Thousand Talents Plan secretariat and the MoE did not respond to the Nature Index’s inquiries.

“Every scientist should be concerned — not just scientists of Chinese origin,” says Xi Xiaoxing, a physicist at Temple University. He argues the US government’s rhetoric threatens not just academic freedom but the US’s place in science and technology globally.

Xi was arrested by the FBI in 2015 and charged with sharing sensitive technology with China, but the case was abruptly dropped four months later.

Against the backdrop of an ongoing trade war, the threat to China–US scientific co-operation could also setback the global scientific enterprise. The two countries are the top collaborating pair in the production of high-quality scientific research worldwide, based on their joint authorship contributions to articles in the 82 journals tracked by the Nature Index.

The developments have had a “chilling effect on young people,” says Wang Xiao-Fan, a cell and molecular biologist at Duke University School of Medicine.

Deterring Chinese students would cost US institutions dearly, says Wang. About a third of all US science and engineering master’s and doctorate degrees in 2015 were awarded to international students. Of the doctorate recipients on temporary visas between 1995 and 2015, some 29%, or 63,576, were from China.

Scholars or spies
The Chinese threat to US innovation and industry has been a longstanding concern, but recent developments have put China’s talent programmes in the spotlight.

China's drives to recruit scholars and technology experts are a primary channel for harvesting US technologies and intellectual property, stated a June 2018 White House Office of Trade and Manufacturing Policy document.

At an April 2018 hearing titled “Scholars or Spies”, organized by two subcommittees of the US House of Representatives, the commissioner of the U.S.-China Economic and Security Review Commission, Michael Wessel, advised Congress to cut federal grants, loans or other assistance to participants of the Thousand Talents Plan. China has put “sleeper agents at our research universities to steal our scientific breakthroughs,” said Representative Lamar Smith, chairman of the House Committee on Science, Space and Technology, at the hearing.

Foreign entities were mounting “systematic programs to influence NIH researchers and peer reviewers” warned Francis Collins, director of the largest public funder of biomedical research, the National Institutes of Health (NIH), in a letter sent to thousands of research institutes on 20 August 2018. Collins, who did not directly refer to China, encouraged institutions to get in touch with FBI field offices to organise briefings on the subject.

The Thousand Talents Plan, launched in 2008 and expanded in 2011 to include younger and foreign researchers, is under particular scrutiny. It has attracted more than 7,000 individualsback to China with lucrative and prominent positions and substantial research grants. The majority of returnees have come from the US, with some top-level candidates maintaining dual US–Chinese institutional affiliations.

Warning of threats
In an episode that has severely rattled Chinese researchers, also in August, the FBI Houston Division held a briefing at The University of Texas MD Anderson Cancer Center to warn medical and research representatives of threats posed by foreign adversaries, including theft of proprietary information and research funds.

Accounts spread within the Chinese researcher community that several faculty at MD Anderson with ties to the Thousand Talents Plan were questioned following the briefing. In one case confirmed by Nature Index, an individual who had been offered a position through the plan, but had not accepted it, was questioned.

Connor Hagan, a public affairs officer for FBI Houston cites usual FBI policy in declining to confirm or deny the existence of an investigation. MD Anderson states that it has “not dismissed any staff or visiting scientists as a result of their participation in the Thousand Talents program”.

In a separate development, Joseph Heppert, vice-president for research at Texas Tech University, disclosed in a letter addressed to staff that a faculty of the university had been advised to suspend his application to the Thousand Talents Plan after consulting with the FBI.

Widespread alarm
Lin Xin, an immunologist and cancer biologist at Tsinghua University is offended at the suggestion that scholars are engaged in espionage activities.

Lin returned to China with support from the Thousand Talents Plan after several years at MD Anderson, formally resigning from his US position at the end of 2016. “It is just a recruitment plan,” he says. “We want the research community to be able to freely talk about their work.”

Some researchers who were considering applying for the Thousand Talents Plan are having second thoughts for fear they could become a target of the US administration.

The removal of information from websites in China has been unsettling, says a Chinese bioinformatics and computational biologist based in the US, who spoke on the condition of anonymity. “Now that everything is not transparent, we are not sure whether the selection criteria will be fair.”

Tobin Smith, vice president for policy at the 60-strong Association of American Universities, says that institutions are working to understand the government’s concerns. Researchers might have unwittingly shared sensitive information with foreign actors, he suggests. “But at this point it is still a bit unclear what the threat from the programmes actually is,” he says.

Futao Huang, a higher-education policy analyst at Hiroshima University in Japan, argues that the shroud of scepticism hanging over Chinese talent programmes will interfere with China’s goals of advancing in fields such as artificial intelligence, where the US is the current leader. “The best researchers will stay in the US,” he says.

doi: 10.1038/d41586-018-07167-6

 

[JSCh]

NEWS AND VIEWS | 24 OCTOBER 2018
Precise control of infrared polarization using crystal vibrations
A natural material has been discovered that exhibits an extreme optical property known as in-plane hyperbolicity. The finding could lead to infrared optical components that are much smaller than those now available.

Hyperbolic materials are highly reflective to light along a certain axis and reflective to light along a perpendicular axis. Typically, one of these axes is in the plane of the material and the other is out of the plane. A material in which both of these axes are in the plane would enable, for example, the manufacture of ultrathin waveplates — optical components that alter the polarization of incident light. Moreover, the reflective behaviour of this material would allow light to be confined and manipulated at extremely small scales (less than one-hundredth the wavelength of the light). In a paper in Nature, Ma et al.1 report the existence of such in-plane hyperbolicity in the natural material molybdenum trioxide.

​

Many crystals exhibit birefringence, in which their refractive index — a measure of the speed of light in a material — is different along different axes. This property can be used to manipulate the polarization of incident light. The crystal size that is required to achieve sufficient polarization control for practical applications is directly proportional to the wavelength of the incident light and to the strength of the birefringence. Consequently, for light in the mid- to far-infrared regions of the electromagnetic spectrum (with wavelengths of 3–300 micrometres), the crystals typically need to be a few millimetres thick2. To overcome this requirement, a potential solution is to consider materials that exhibit hyperbolicity, which is an extreme form of birefringence.

Hyperbolicity was originally thought to exist only in artificial materials consisting of integrated reflective and transparent domains3. But in 2014, it was observed in the natural material hexagonal boron nitride4,5. The reflective behaviour of both this material and molybdenum trioxide is derived from crystal-lattice vibrations, known as optical phonons, that oscillate in a highly anisotropic (direction-dependent) way. These phonons have relatively long lifetimes (in excess of a picosecond; 1 ps is 10−12 s), which strongly suppresses the absorption of light by the material6. Since the discovery of hyperbolicity in hexagonal boron nitride, a broad array of natural hyperbolic materials has been identified7.

Preliminary investigations of molybdenum trioxide were reported earlier this year8 and showed the existence of hyperbolicity for long-wave infrared light (with wavelengths of 8–14 µm). Ma and colleagues have now demonstrated and characterized in-plane hyperbolicity for the same spectral range. They used this property to confine light to dimensions substantially smaller than its wavelength, through the formation of hybrid light–matter excitations called hyperbolic phonon polaritons. The authors report lifetimes for such polaritons of up to 20 ps, which is about ten times longer than the best values reported for hexagonal boron nitride9.

Because the crystal structure of molybdenum trioxide is highly anisotropic, all three crystal axes, which define the edges of the crystal’s unit cell, have different lengths. Consequently, there is a large difference in the phonon energies associated with these axes and therefore in the corresponding refractive indices — resulting in a birefringence of about 0.31. It should be noted that, earlier this year, a similarly large in-plane birefringence of 0.76 was reported in the natural material barium titanium sulfide for mid-infrared to long-wave infrared light10. However, hyperbolicity was not observed for this material.

The in-plane hyperbolicity of molybdenum trioxide offers opportunities to replace conventional optical components with ones that are much smaller. In particular, using the large in-plane birefringence of this material (or of barium titanium sulfide), infrared waveplates could be constructed from thin slabs that have thicknesses on the order of tens of micrometres (Fig. 1a). Such waveplates could operate in the long-wave infrared, for which commercial waveplates are not widely available and have thicknesses in excess of 1 mm.

Figure 1 | Manipulating infrared polarization. Ma et al.1 show that the material molybdenum trioxide can be used to precisely control the polarization of infrared light.a, Optical components known as waveplates can convert linearly polarized light into circularly polarized light. In the infrared, a waveplate made of a conventional material requires a thickness in excess of 1 millimetre. This material could be replaced with a thin slab of molybdenum trioxide, with a thickness on the order of tens of micrometres. b, Components called polarizers can convert unpolarized light (in which the polarization points in all directions) into linearly polarized light. In the infrared, polarizers made from conventional materials typically need to be thick and use a large grid of metal wires. Such a structure could be replaced with a thin film of molybdenum trioxide that requires essentially no fabrication. c, Nanoscale photonic structures made from conventional materials can emit unpolarized infrared light. But if molybdenum trioxide were used, linearly polarized emission could be achieved.

Furthermore, using the material’s in-plane hyperbolicity, polarizers — components that extinguish undesired polarizations of incident light — could be made from simple 1-µm-thick films (Fig. 1b). Previously, polarizers needed to be thicker and typically required a large grid of metal wires to be patterned on their surface. The remarkable properties of molybdenum trioxide could therefore greatly reduce both the size and the cost of optical components, offering broad applicability in thin, compact infrared devices.

Beyond conventional optics, the properties of molybdenum trioxide could lead to advances in the realm of nanophotonics, which focuses on confining light to nanoscale dimensions. In the long-wave infrared, where the hyperbolicity of this material is observed, nanoscale light confinement necessarily implies defeating the diffraction limit — the usual restriction that light cannot be squeezed into dimensions much smaller than its wavelength. Molybdenum trioxide can beat this limit and, as a result, presents opportunities for producing improved infrared-emitting devices.

For instance, heating nanoscale photonic structures made from materials that can support polaritons can produce light of one or more specific frequencies — rather than light of a broad range of frequencies that that emitted by, for example, conventional light bulbs. Such structures provide an optical source that is akin to light-emitting diodes, but that can be designed to operate anywhere in the infrared. The emitted light from these photonic structures is usually unpolarized (Fig. 1c). It is only through the use of materials that exhibit in-plane hyperbolicity that light of a single, pure polarization can be generated.

Finally, hyperbolic materials such as molybdenum trioxide could serve as the basis for hyperlenses — lenses that produce magnified images of objects smaller than the wavelength of the imaging light. They could also be used in heterostructures (structures in which layers of different materials are combined) to make nanophotonic components that have controllable properties11,12.

Ma and colleagues have demonstrated that, once again, nature has more in store for us than we thought. The future of nanophotonics was once considered to be in the realization of artificial materials, but this study and others in the past few years have demonstrated that, in many cases, the best approach for finding advanced materials is to look among the vast array of natural materials. The results of these studies offer substantial advances in the fields of infrared optics and nanophotonics that could enable infrared imaging and detection to become as ubiquitous as its visible counterpart — a vision that would enable imaging through smoke for first responders, near-instant medical diagnostics and enhanced chemical spectroscopy.

Nature 562, 499-501 (2018)

doi: 10.1038/d41586-018-07087-5


Precise control of infrared polarization using crystal vibrations | Nature

Weiliang Ma, Pablo Alonso-González, Shaojuan Li, Alexey Y. Nikitin, Jian Yuan, Javier Martín-Sánchez, Javier Taboada-Gutiérrez, Iban Amenabar, Peining Li, Saül Vélez, Christopher Tollan, Zhigao Dai, Yupeng Zhang, Sharath Sriram, Kourosh Kalantar-Zadeh, Shuit-Tong Lee, Rainer Hillenbrand & Qiaoliang Bao. In-plane anisotropic and ultra-low-loss polaritons in a natural van der Waals crystal. Nature (2018). DOI: 10.1038/s41586-018-0618-9​

 

[JSCh]

Nation ranks 2nd in global research
By Zhang Zhihao | China Daily | Updated: 2018-10-25 08:00

A visitor checks out a medical robot conducting simulated surgery on a grape at the opening of the Zhongguancun Innovation and Entrepreneurship Festival in Beijing. [Photo by Wang Zhuangfei/China Daily]

China leads the world in 32 out of 138 research topics in groundbreaking natural and social science fields, second only to the United States, according to the Research Fronts 2018 report published on Wednesday.

The results were based on analysis of research fronts－a cluster of highly cited papers over a five-year period－which can help determine areas where key work is being done and where the scientific community is most active. This allows researchers and officials to identify scientific trends and areas of possible collaboration.

Last year, China led in 25 topics in the report, which was compiled by the Chinese Academy of Sciences' Institute of Science and Development and Clarivate Analytics, a global analytics firm. The report has been published annually since 2014.

In 2018, the US topped the world, leading in 82 topics. Germany and United Kingdom ranked third and fourth, leading in six and four fields, respectively.

Zhang Tao, vice-president of the Chinese Academy of Sciences, said China must strengthen basic research and make breakthroughs in frontier sciences to become a global technological powerhouse.

"Our scientific development has entered a new era," Zhang said, adding that grasping future research trends in key fields is crucial to serving the nation's innovation and development strategies.

The report's research fronts are divided into 10 broad areas. Of those, the US leads in eight in research activity and influence, while China leads in two, chemistry/materials sciences and math/computer sciences.

Chemistry/material sciences is also a fiercely contested field between China and the US, in which both countries are highly active and influential. China has a slight edge over the US so far in 2018.

However, China is noticeably behind the US in terms of active research in fields such as clinical medicine, astronomy and astrophysics. It also needs to put more effort into researching economics, psychology and other social sciences fields, the report said.

Chen Runsheng, a CAS biophysicist and academician, said knowing about frontier sciences and global scientific trends can help nations reap the benefits of new technologies and address new challenges.

"The line between using biotechnology to benefit or harm society has now become increasingly thin," Chen said.

 

[JSCh]

PUBLIC RELEASE: 25-OCT-2018
Invention by NUS chemists opens the door to safer and less expensive X-ray imaging
Highly sensitive X-ray detector that incorporates novel nanocrystals reduces diagnostic radiation dose

NATIONAL UNIVERSITY OF SINGAPORE

Medical imaging, such as X-ray or computerised tomography (CT), may soon be cheaper and safer, thanks to a recent discovery made by chemists from the National University of Singapore (NUS).

Professor Liu Xiaogang and his team from the Department of Chemistry under the NUS Faculty of Science had developed novel lead halide perovskite nanocrystals that are highly sensitive to X-ray irradiation. By incorporating these nanocrystals into flat-panel X-ray imagers, the team developed a new type of detector that could sense X-rays at a radiation dose about 400 times lower than the standard dose used in current medical diagnostics. These nanocrystals are also cheaper than the inorganic crystals used in conventional X-ray imaging machines.

"Our technology uses a much lower radiation dose to deliver higher resolution images, and it can also be used for rapid, real-time X-ray imaging. It shows great promise in revolutionising imaging technology for the medical and electronics industries. For patients, this means lower cost of X-ray imaging and less radiation risk," said Prof Liu.

The team's research breakthrough was the result of a collaborative effort with researchers from Australia, China, Hong Kong, Italy, Saudi Arabia, Singapore and the United States. It was first published in the online edition of Nature on 27 August 2018, and a patent for this novel technology has been filed.

Nanocrystals light the way for better imaging

X-ray imaging technology has been widely used for many applications since the 1890s. Among its many uses are medical diagnostics, homeland security, national defence, advanced manufacturing, nuclear technology, and environmental monitoring.

A crucial part of X-ray imaging technology is scintillation, which is the conversion of high-energy X-ray photons to visible luminescence. Most scintillator materials used in conventional imaging devices comprise expensive and large inorganic crystals that have low light emission conversion efficiency. Hence, they will need a high dose of X-rays for effective imaging. Conventional scintillators are also usually produced using a solid-growth method at a high temperature, making it difficult to fabricate thin, large and uniform scintillator films.

To overcome the limitations of current scintillator materials, Prof Liu and his team developed novel lead halide perovskite nanocrystals as an alternative scintillator material. From their experiments, the team found that their nanocrystals can detect small doses of X-ray photons and convert them into visible light. They can also be tuned to light up, or scintillate, in different colours in response to the X-rays they absorb. With these properties, these nanocrystals could achieve higher resolution X-ray imaging with lower radiation exposure.

To test the application of the lead halide perovskite nanocrystals in X-ray imaging technology, the team replaced the scintillators of commercial flat-panel X-ray imagers with their nanocrystals.

"Our experiments showed that using this approach, X-ray images can be directly recorded using low-cost, widely available digital cameras, or even using cameras of mobile phones. This was not achievable using conventional bulky scintillators. In addition, we have also demonstrated that the nanocrystal scintillators can be used to examine the internal structures of electronic circuit boards. This offers a cheaper and highly sensitive alternative to current technology," explained Dr Chen Qiushui, a Research Fellow with the NUS Department of Chemistry and the first author of the study.

Using nanocrystals as scintillator materials could also lower the cost of X-ray imaging as these nanocrystals can be produced using simpler, less expensive processes and at a relatively low temperature.

Prof Liu elaborated, "Our creation of perovskite nanocrystal scintillators has significant implications for many fields of research and opens the door to new applications. We hope that this new class of high performance X-ray scintillator can better meet tomorrow's increasingly diversified needs."

Next steps and commercialisation opportunities

To validate the performance of their invention, the NUS scientists will be testing their abilities of the nanocrystals for longer times, and at different temperatures and humidity levels. The team is also looking to collaborate with industry partners to commercialise their novel imaging technique.


Invention by NUS chemists opens the door to safer and less expensive X-ray imaging | EurekAlert! Science News

Qiushui Chen, Jing Wu, Xiangyu Ou, Bolong Huang, Jawaher Almutlaq, Ayan A. Zhumekenov, Xinwei Guan, Sanyang Han, Liangliang Liang, Zhigao Yi, Juan Li, Xiaoji Xie, Yu Wang, Ying Li, Dianyuan Fan, Daniel B. L. Teh, Angelo H. All, Omar F. Mohammed, Osman M. Bakr, Tom Wu, Marco Bettinelli, Huanghao Yang, Wei Huang & Xiaogang Liu. All-inorganic perovskite nanocrystal scintillators. Nature (2018). DOI: 10.1038/s41586-018-0451-1​

 

[JSCh]

China has strongest fibre that can haul 160 elephants – and a space elevator? | South China Morning Post

• Scientists say just 1 cubic centimetre of the carbon nanotube material won’t break under the weight of more than 800 tonnes
• Tsinghua University researchers are trying to get the fibre into mass production for use in military or other areas

PUBLISHED : Friday, 26 October, 2018, 12:03am
UPDATED : Friday, 26 October, 2018, 9:21am

Stephen Chen

A research team from Tsinghua University in Beijing has developed a fibre they say is so strong it could even be used to build an elevator to space.

They say just 1 cubic centimetre of the fibre – made from carbon nanotube – would not break under the weight of 160 elephants, or more than 800 tonnes. And that tiny piece of cable would weigh just 1.6 grams.

“This is a breakthrough,” said Wang Changqing, a scientist at a key space elevator research centre at Northwestern Polytechnical University in Xian who was not involved in the Tsinghua study.

The Chinese team has developed a new “ultralong” fibre from carbon nanotube that they say is stronger than anything seen before, patenting the technology and publishing part of their research in the journal Nature Nanotechnology earlier this year.

“It is evident that the tensile strength of carbon nanotube bundles is at least 9 to 45 times that of other materials,” the team said in the paper.

They said the material would be “in great demand in many high-end fields such as sports equipment, ballistic armour, aeronautics, astronautics and even space elevators”.

Science fiction?
The idea of building a lift that could travel from the Earth into space may sound like the stuff of science fiction, but it has been around for more than a century, and scientists have come up with various designs in recent decades.

One of them involves sending a large satellite into geostationary orbit that would lower a cable to the ground, where it would be anchored, and send another cable in the opposite direction, attached to a counterweight.

The theory is that the lift would be suspended between two cables – pulled taut by gravity and centrifugal force, and rotating with the Earth, like a weight on a piece of string being swung around in circles.

But so far, the space elevator idea has remained in the realm of physical and mathematical models because there has been no material strong enough to make the super-light, ultra-strong cables needed.

​

Those cables would need to have tensile strength – to withstand stretching – of no less than 7 gigapascals, according to Nasa. In fact, the US space agency launched a global competition in 2005 to develop such a material, with a US$2 million prize attached. No one claimed the prize.

Now, the Tsinghua team, led by Wei Fei, a professor with the Department of Chemical Engineering, says their latest carbon nanotube fibre has tensile strength of 80 gigapascals.

Carbon nanotubes are cylindrical molecules made up of carbon atoms that are linked in hexagonal shapes with diameters as small as 1 nanometre. They have the highest known tensile strength of any material – theoretically up to 300 gigapascals.

But for practical purposes, these carbon nanotubes must be bonded together in cable form, a process which is difficult and can affect the overall strength of the final product.

According to Wang, the space lift researcher, the transport system would need more than 30,000km of cable, and it would also need other structures such as a rail and a shield to protect against space debris and other environmental hazards.

“If the cable is not strong enough, it would not even be able to support its own weight. Until now, there has been no material tough enough to do the job,” said Wang, deputy executive director of the China-Russia International Space Tether System Research Centre.

Requirements for cable strength vary according to the space lift design. Wang said the carbon nanotube fibre appeared to be the most promising candidate for now, but more calculations and simulation were needed to evaluate how it would perform.

“The tether is one big problem, but it is not the only problem,” he added.

Chinese and Russian space scientists, for instance, are working together to find a safe, effective way to lower a fine, feather-light cable from a high-altitude orbit to the ground. Re-entry to the atmosphere can produce a lot of heat that could burn the cable, while the counterweight may need to be as large as an asteroid to keep the line straight.

The scale and complexity of such a project would dwarf the International Space Station, according to Wang.

But countries including China, the United States, Russia and Japan continue to support the research. So-called space tether technology has the potential to be used for military purposes, including capturing “non-cooperative targets” including enemy satellites.

Japan launched two satellites last month in an experiment to study elevator movement in space – the first time this has been done – involving a mini-lift travelling along a cable from one satellite to another. It has yet to report the results of the experiment. China has also conducted space tethering tests but the details were classified.

Electric cars and laser cannons
While a lift to space could still be many years away, Wei said his team was trying to get the carbon nanotube fibre into mass production for use in defence or other areas.

“This could be a game changer in many sectors,” he said.

Wei gave the example of superfast flywheels in a mechanical battery – where the flywheel stores energy in a rotating mass, lifted by magnetic levitation in a vacuum chamber. The lighter and stronger the material, the faster it spins.

Using carbon nanotube flywheels, the mechanical battery would have 40 times the energy density of a lithium battery, according to Wei. That would mean a car like a Tesla Model S could travel for 16,000km in one charge – the distance from London to Sydney.

But the technology is likely to be used for military purposes first, Wei said.

“Many new weapon systems such as rail guns and laser cannons require high performance power storage and supply systems, and our technology offers a possible solution,” he said.

The researchers made the longest carbon nanotube in the world in 2013 – measuring half a metre – and recently developed a 70cm one.

Song Liwei, who studies mechanical batteries at the Harbin Institute of Technology in Heilongjiang, said if the carbon nanotube fibre could be mass-produced and if it significantly increased the energy density of mechanical batteries, it “would kill fossil fuel engines”.

“But the flywheels can be as big as a barrel, and the fibre would need to be several kilometres long to make a battery,” he said. “There is still a long way to go.”

 

[JSCh]

New Chinese Sequencer Promises 60 Human Genomes In A Day - Bio-IT World
By Bio-IT World Staff

October 25, 2018 | MGI Tech (part of BGI), introduced the next iteration of its sequencer, the MGISEQ-T7, at the 13th International Conference on Genomics (ICG-13) in Shenzhen. The company also announced new library and sample prep and an application for tumor mutation detection.

The proprietary MGI technology used in T7 delivers higher accuracy and improves efficiency through upgrades to the flowcell, fluid, and biochemical and optical system. The new sequencer delivers quadruple flowcell staging that allows simultaneous but independent operation of 1 to 4 flowcells in a single run.

The platform supports whole genome sequencing, ultra-depth exome sequencing, epigenome sequencing, and large-panel tumor gene detection, and has a daily data output capacity of up to 6Tb. The company reports that MGISEQ-T7 can complete whole genome sequencing for up to 60 human genomes in a single day.

“MGI is developing at an unprecedented speed, and our technology has advanced to lead the market,” said MGI CEO Feng Mu in a statement. “This new instrument demonstrates the level of MGI’s innovation and commitment to progress: we continually challenge ourselves and drive towards our goal to make highly accurate next generation sequencing more affordable to benefit more people around the world.”

The MGISEQ-T7 includes:

Unique Quad-Flowcell Platform, supporting independent operation of 1-4 chips

A quad-flowcell platform enables multiple flowcells with different read lengths and applications to be processed independently at any time in a single run, saving time and cost.

Sequencing speed has increased by over 50%, completing PE 150 in less than 24 hours

Whether it’s a single chip or four chips running simultaneously, MGISEQ-T7 can maintain its consistently strong processing capacity. With MGISEQ-T7, PE150 takes less than 24 hours at full load to complete.

Single chip density increased by 20%, achieving ultra-high throughput

Terabyte-level data can be produced with a single chip. Without interruptions for 24 hours, running 4 chips independently, MGISEQ-T7 can produce up to 6Tb of data in one day.

In addition to the T7, MGI announced improved sample prep and library prep for long fragment reads, and an additional application to the MegaBOLT bioinformatics accelerator. For sample prep, MGI has developed an automated sample preparation system based on the needs of ultra-high-throughput genomic sequencing. The new MGISP-960, which has a higher throughput and can prepare 96 samples in one run, is a major advance from the previously released MGISP-100 that can automatically prepare 8 samples in one run. There is also a new library preparation kit for single tube Long Fragment Reads (stLFR) technology, which significantly reduces the cost and complexity of long fragment library preparation. It was introduced in March, and will be commercially available in December.

Finally, MegaBOLT Somatic is an extended application for tumor mutation detection based on the MegaBOLT bioinformatics accelerator released in May. MegaBOLT Somatic dramatically cuts the time needed for tumor analysis, down to two hours for WGS and 10 minutes for WES. The cost reduction and the speed increase of MegaBOLT Somatic will provide alternatives for tumor gene sequencing analysis to benefit patients and researchers.

 

[JSCh]

Scientists find neurons that help rats "make wise decisions"
Xinhua | Updated: 2018-10-26 11:44

When facing mounting tasks, will you continue to work or indulge in a cup of coffee? Behind this choice lies key brain activity that decides "what's more important."

Scientists have said they have located a part of the rat's brain involved in this process of importance ranking, a discovery that will prompt the search for a similar mechanism in humans.

The study by a team of Chinese and American scientists was published in the prestigious journal Science Friday.

First author Zhu Yingjie from Shenzhen Institutes of Advanced Technology of the Chinese Academy of Sciences said they found that a part of the rat's brain called the paraventricular thalamus (PVT) was closely related to tracking the behavioral importance or "salience" of stimuli.

"What happens in your brain when you decide how to spend your evening, to work overtime or to drink a beer? Saliency detection is a key brain mechanism that facilitates learning and survival by enabling organisms to focus their limited attention on the most important event," Zhu said.

He explained that neurons in PVT were robustly activated by salient stimuli. Through experiments, they found PVT was highly active when a thirsty rat found water, and would remain active even when the rodent was harassed by air puffers, suggesting its brain regarded water as a very important stimulus.

PVT activity, however, fell to a low level when the rat faced heavier punishments like electric shocks, which prompted the animal to give up water to avoid pain. The salience of water, as illustrated by PVT activity, also dropped when the rat became sated after a drinking binge.

"PVT can dynamically track the salience of stimuli upon changes in internal homeostatic state and external environment," Zhu told Xinhua. "Our initial prediction is that human brains have similar mechanisms."

The rising and ebbing salience of stimuli are common in our lives, like how an old couple who experience fading passion may find love reignited when environmental factors change.

"Our future researches will focus on the possibilities that we can improve people's attention and learning by controlling PVT activities," Zhu said.

Robert Malenka, deputy director of Stanford Neurosciences Institute, who was not involved in the study, said the paper expanded the role of the thalamus and explained how it played a critical role in learning and memory.

"It also raised the possibility that pathological processes in the brain region may play an important role in a variety of common brain disorders including drug addiction and depression."

 

[JSCh]

Novel Material Could Make Plastic Manufacturing More Energy-Efficient
October 25, 2018

An innovative filtering material may soon reduce the environmental cost of manufacturing plastic. Created by a team including scientists at the National Institute of Standards and Technology (NIST), the advance can extract the key ingredient in the most common form of plastic from a mixture of other chemicals—while consuming far less energy than usual.

The material is a metal-organic framework (MOF), a class of substances that have repeatedly demonstrated a talent for separating individual hydrocarbons from the soup of organic molecules produced by oil refining processes. MOFs hold immense value for the plastic and petroleum industries because of this capability, which could allow manufacturers to perform these separations far more cheaply than standard oil-refinement techniques.

​

Credit: N. Hanacek/NIST

This promise has made MOFs the subject of intense study at NIST and elsewhere, leading to MOFs that can separate different octanes of gasoline and speed up complex chemical reactions. One major goal has proved elusive, though: an industrially preferred method for wringing out ethylene—the molecule needed to create polyethylene, the plastic used to make shopping bags and other everyday containers.

However, in today’s issue of the journal Science, the research team reveals that a modification to a well-studied MOF enables it to separate purified ethylene out of a mixture with ethane. The team’s creation—built at The University of Texas at San Antonio (UTSA) and China’s Taiyuan University of Technology and studied at the NIST Center for Neutron Research (NCNR)—represents a major step forward for the field.

Making plastic takes lots of energy. Polyethylene, the most common type of plastic, is built from ethylene, one of the many hydrocarbon molecules found in crude oil refining. The ethylene must be highly purified for the manufacturing process to work, but the current industrial technology for separating ethylene from all the other hydrocarbons is a chilly but high-energy process that cools down the crude to more than 100 degrees below zero Celsius.

Ethylene and ethane constitute the bulk of the hydrocarbons in the mixture, and separating these two is by far the most energy-intensive step. Finding an alternative method of separation would reduce the energy needed to make the 170 million tons of ethylene manufactured worldwide each year.

Scientists have been searching for such an alternative method for years, and MOFs appear promising. On a microscopic level, they look a bit like a half-built skyscraper of girders and no walls. The girders have surfaces that certain hydrocarbon molecules will stick to firmly, so pouring a mixture of two hydrocarbons through the right MOF can pull one kind of molecule out of the mix, letting the other hydrocarbon emerge in pure form.

The trick is to create a MOF that allows the ethylene to pass through. For the plastics industry, this has been the sticking point.

“It’s very difficult to do,” said Wei Zhou, a scientist at the NCNR. “Most MOFs that have been studied grab onto ethylene rather than ethane. A few of them have even demonstrated excellent separation performance, by selectively adsorbing the ethylene. But from an industrial perspective you would prefer to do the opposite if feasible. You want to adsorb the ethane byproduct and let the ethylene pass through.”

The research team spent years trying to crack the problem. In 2012, another research team that worked at the NCNR found that a particular framework called MOF-74 was good for separating a variety of hydrocarbons, including ethylene. It seemed like a good starting point, and the team members scoured the scientific literature for additional inspiration. An idea taken from biochemistry finally sent them in the right direction.

​

This iron-based metal-organic framework decorated with peroxo groups can capture ethane while allowing ethylene to pass through, potentially providing a more efficient and cost-effective way to purify ethylene, the most important raw material for plastic production.
Credit: W. Zhou / NIST

“A huge topic in chemistry is finding ways to break the strong bond that forms between carbon and hydrogen,” said UTSA professor Banglin Chen, who led the team. “Doing that allows you to create a lot of valuable new materials. We found previous research that showed that compounds containing iron peroxide could break that bond.”

The team reasoned that to break the bond in a hydrocarbon molecule, the compound would have to attract the molecule in the first place. When they modified MOF-74’s walls to contain a structure similar to the compound, it turned out the molecule it attracted from their mixture was ethane.

he team brought the MOF to the NCNR to explore its atomic structure. Using a technique called neutron diffraction, they determined what part of the MOF’s surface attracts ethane —a key piece of information for explaining why their innovation succeeded where other efforts have fallen short.

“Without the fundamental understanding of the mechanism, no one would believe our results,” Chen said. “We also think that we can try to add other small groups to the surface, maybe do other things. It’s a whole new research direction and we’re very excited.”

While Zhou said the team’s modified MOF does work efficiently, it may require some additional development to see action at a refinery.

“We proved this route is promising,” Zhou said, “but we’re not claiming our materials perform so well they can’t be improved. Our future goal is to dramatically increase their selectivity. It’s worth pursuing further.”



Novel Material Could Make Plastic Manufacturing More Energy-Efficient | NIST

Libo Li, Rui-Biao Lin, Rajamani Krishna, Hao Li, Shengchang Xiang, Hui Wu, Jinping Li, Wei Zhou & Banglin Chen. Ethane/ethylene separation in a metal-organic framework with iron-peroxo sites. Science (2018). DOI: 10.1126/science.aat0586​

 

[JSCh]

Tigers confirmed as six subspecies, and that is a big deal for conservation | theconversation.com
October 26, 2018 2.19am AEDT

Tara Pirie
Postdoctoral Researcher, People and Wildlife Research Group, University of Reading

During my time as a zookeeper I had the privilege of working with both Sumatran and Amur tigers. If they did not both have stripes, you would think they were different species altogether.

The Sumatran tiger is the smallest alive today. At around 100kg, it’s “only” about the weight of a large adult male human. It is suited to the warm and wet forests of the Indonesian island of Sumatra, which is reflected in its smaller size and short, dark rusty orange coat which has many thin black stripes to conceal it in dense vegetation from their prey.

The Amur – or Siberian – tiger is much larger, averaging around 170kg (though there are historic reports of males clocking in at 300kg or more) and is now found mainly one corner of far-eastern Russia. It has a thicker but relatively pale coat, with sparse dark brown stripes, which enables it to survive in freezing and snowy winters.

Tiger experts have long debated what such differences mean scientifically. Should the biggest of the big cats be divided into various subspecies, or are all tigers simply “tigers”?

It’s an issue with serious implications for conservation. About 3,500 or so tigers remain in the wild, in just 7% of their former range. And if those tigers are all the same, or if even most of them are the same, then saving individual populations matters slightly less – and tigers can be moved around to assist breeding in the wild.

​

Sumatran tigers have adapted to hiding in the jungle. tom177 / shutterstock

Traditionally, eight subspecies were considered to exist. They are the two already mentioned, plus the Bengal tiger, found mainly in India, the Indochinese, the South China tiger and then three extinct subspecies: the Bali (extinct in the 1940s) and Javan (80s), both closely related to surviving tigers on nearby Sumatra, and the Caspian tiger from Central Asia which went extinct in the 1970s.

As genetic techniques evolved, a 2004 study found there was little genetic diversity among tigers, but enough to support the separation of subspecies. It also suggested that Indochinese tigers living on the Malayan peninsular were different enough to those living further north to warrant a ninth subspecies: the Malayan tiger.

These ideas were contested by a group of researchers in 2015, who argued that the relative lack of variation among the mainland Asian subspecies and large overlaps in their shape, size and ecology meant that all tigers from India to Siberia or Thailand should be considered the same subspecies. The researchers called for just two recognised subspecies: the continental tiger, and the Sunda tiger, found on the various Indonesian islands.

However the various subspecies are classified, one of the consistent findings is that tigers follow Bergmann’s rule: a principle in zoology which states that animals within the same overall species will tend to be larger in colder environments and vice versa. The Amur tiger, for instance, benefits from the fact that larger animals are better at retaining heat as they have a smaller surface area relative to their overall mass.

Six genetically distinct groups
This is where a new study published in the journal Current Biology fits in. Researchers from China and the US looked at the whole genomes of 32 representative tigers and found that there were indeed nine subspecies of tiger – of which six survive today. But their work also demonstrates that the various adaptations to temperature – Amur big and hairy, Sumatran small and sleek – were triggered by significant prehistoric events that changed global and local temperatures.

​

Map showing dispersal routes and range expansions of modern tigers. Liu et al. / Current Biology, CC BY-SA

The findings confirm previous speculation that the low genetic diversity in tigers was caused by a population decline during an ice age 110,000 years ago. Thousands of years later, the earliest split from a single common ancestor species occurred between island and mainland subspecies, with the former developing a smaller body size thanks to natural selection. The super eruption of the Sumatran volcano Toba 75,000 years ago followed by an extreme cooling period was the likely cause. Further splits into more specialised tigers reflect other significant extreme climatic changes.

This affects conservation tactics
So why is this important in terms of tiger conservation? As past research has argued, the lack of genetic and morphological differences between mainland tigers could allow them to be managed as single subspecies. Theoretically individuals from any region, wild or captive, could be relocated to repopulate former areas or increase numbers of failing local populations. This could help to increase general tiger numbers and local genetic diversity.

​

Siberian tigers are bigger, hairier and have fewer stripes. Vaclav Sebek / shutterstock

But the recent study suggests that tiger adaptations may be more subtle and intricate than first appeared. If tigers are allowed to hybridise either in captive or wild populations it could drive the more vulnerable subspecies to extinction before we fully understand exactly how they have adapted to their particular area.

There is a downside to considering tigers as separate subspecies and attempting to protect them on this basis, without mixing in tigers from elsewhere. Numbers of each subspecies are very small – there are only around 500 wild Amurs, for instance – and smaller populations are more vulnerable to extinction. This could be caused by the regular threats of habitat loss and poaching or simply due to reduced genetic diversity making a small population vulnerable to disease and other selective pressures.

Genetic diversity is key for adaptation and ultimately species survival. As our understanding increases, more informed decisions can be made regarding how best to conserve the tiger. We might not have enough time to solve all the riddles but perhaps this is one step closer to ensuring one of the world’s most iconic animals does not disappear forever.

Yue-Chen Liu, Xin Sun, Carlos Driscoll, Dale G. Miquelle, Xiao Xu, Paolo Martelli, Olga Uphyrkina, James L.D. Smith, Stephen J. O'Brien, Shu-Jin Luo. Genome-Wide Evolutionary Analysis of Natural History and Adaptation in the World's Tigers. Current Biology (2018). DOI: 10.1016/j.cub.2018.09.019​

 

[JSCh]

Watch these wooden sponges wick up spilled oil | Science | AAAS
By Katherine Kornei Oct. 29, 2018 , 1:15 PM

Oil spills are messy and harmful to local ecosystems—just ask anyone on the Louisiana coast. So far, there’s no foolproof way to clean them up, and some methods—like burning the oil—can result in even more pollution. Now, researchers have come up with a potential solution: reusable, oil-wicking sponges made of wood that can absorb more than 40 times their weight in oil.

To make the sponges, scientists started with balsa wood, a low-density material often used in model airplanes. The researchers used chemicals to break down the wood’s cell walls and remove the polymers, lignin and hemicellulose, that make it rigid and strong. The resulting highly porous “scaffold” had a density just one-third that of balsa wood. The researchers then topped the scaffold with a coating that repelled water but readily absorbed oil.

The team tested its sponges on a variety of oils—such as motor oil and the industrial solvent dichloromethane—dispersed in water. The sponges wicked up between 16 and 41 times their weight in oil and could be used as a filter to continuously remove oil from a solution (video above). What’s more, the sponges could be reused more than 10 times after they’ve been wrung out, the researchers report this month in ACS Nano.


Watch these wooden sponges wick up spilled oil | Science | AAAS

Hao Guan, Zhiyong Cheng & Xiaoqing Wang. Highly Compressible Wood Sponges with a Spring-like Lamellar Structure as Effective and Reusable Oil Absorbents. ACS Nano (2018). DOI: 10.1021/acsnano.8b05763​

 

[JSCh]

PUBLIC RELEASE: 29-OCT-2018
'Milder' ammonia synthesis method should help environment
CHINESE ACADEMY OF SCIENCES HEADQUARTERS

​

This image shows production of ammonia via a chemical looping process. CREDIT: GAO Wenbo

A Chinese research team has developed a "milder" way to synthesize ammonia by requiring lower temperature and pressure than the current method. The process offers great promise for saving energy and reducing carbon dioxide emissions.

The new process was developed by a research team led by Prof. CHEN Ping and Dr. GUO Jianping from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences. It involves a new chemical looping method based on metal hydride and imide. The process operates at atmospheric pressure and 100-350°C, in contrast with the Haber-Bosch process - currently dominating world ammonia production - which operates at 100-200 bars and 350-450°C.

Ammonia helps feed humanity through its role in producing nitrogen fertilizer. It also has the potential to store and transport renewable energy. However, current ammonia production is very energy intensive - consuming1-2% of world energy output. In addition, about 1.9 metric tons of carbon dioxide is produced for every metric ton of ammonia.

"In order to address the challenges of the energy and environmental crisis, we developed an alternative process for ammonia synthesis from nitrogen gas, water and renewable energy," said CHEN, the study's lead researcher.

The process uses alkali and alkaline earth metal imides as nitrogen carriers that mediate ammonia production via a two-step chemical looping process operating under mild conditions.

"In the first step, nitrogen was fixed through the reduction of nitrogen gas by alkali or alkaline earth metal hydrides to form imides," said CHEN. "In the second step, the imides were hydrogenated to produce ammonia and regenerated the metal hydrides."

CHEN explained that the two steps could be accelerated by the catalysis of transition metals. "The chemical loop mediated by BaNH and catalyzed by Ni could produce ammonia in the temperature range of 100 to 350°C and atmospheric pressure. The production rate of ammonia was more than one order of magnitude higher than that of the thermocatalytic process," CHEN added.

CHEN noted that the study provides a "promising solution to the efficient harvest and storage of renewable energy." CHEN said the process has the advantage of operating at atmospheric pressure and also offers a means of synthesizing ammonia in a localized, distributed manner.


'Milder' ammonia synthesis method should help environment | EurekAlert! Science News

Wenbo Gao, Jianping Guo, Peikun Wang, Qianru Wang, Fei Chang, Qijun Pei, Weijin Zhang, Lin Liu & Ping Chen. Production of ammonia via a chemical looping process based on metal imides as nitrogen carriers. Nature Energy (2018). DOI: 10.1038/s41560-018-0268-z​