481.1km /hour A new record by China's high-speed train

[Akasa]

I heard somewhere that China is set to be the next "physics superpower"

 

[applesauce]

Sorry Martian, I forgot that you guys fare well on satellite and reactors too. I'll paypal you 51 cents if you show me more.

AMERICAN CENTS?

 

[Martian2]

Sorry Martian, I forgot that you guys fare well on satellite and reactors too. I'll paypal you 51 cents if you show me more.

Sure, I have plenty more. Enjoy.

 

[Martian2]

Nanoparticles promise to revolutionise medicine (BBC News; see second newslink below)

Are you aware of the current Chinese advances in nanotechnology, drug delivery, quantum cryptography, material science, etc.?

Here is a sample of the cool products that might result from China's R&D.

Nanotechnology: Tom Mackenzie on China's giant step into nanotech | Technology | The Guardian
http://www.guardian.co.uk/technology/2009/...echnology-china

BBC NEWS | Health | Nanoparticle lung threat blocked

'Nano-raspberries' for Steamy Windows

Polymers release insulin in response to glucose trigger

China develops world's first quantum cryptography network

New Super-bouyant Material: Life Preserver Might Float A Horse
http://www.sciencedaily.com/releases/2009/...90316092837.htm

[Note: Thank you to "snow is red" for finding the stories.]

 

[Martian2]

Milky Way

China Building Large Radio Telescope For Space Observation

"China Building Large Radio Telescope For Space Observation
by Staff Writers
Shanghai (XNA) Jan 04, 2010

Construction of a 65-meter-diameter radio telescope started Tuesday in Shanghai, an official from one of funders said Wednesday. The telescope, a form of directional radio antenna used in radio astronomy, will be used in tracking and collecting data from satellites and space probes including Chinese astronomical projects like Chang'e lunar probe, YH-1 Mars exploration and other deep space explorations, said Zhan Wenlong, deputy dean of the Chinese Academy of Sciences (CAS).

File image of a large radio telescope (Goldstone)

The facility is also capable of receiving data for Jupiter and Saturn exploration, said Hong Xiaoyu, head of Shanghai Astronomical Observation, which will run the project after it is expected to be fully completed in 2015.

The 200-million-yuan (29.3 million U.S. dollars) project, funded by CAS, Shanghai Municipal Government and Chinese lunar probe project, will have a bowl-like surface composed by 1,008 panels as large as eight basketball courts in total area, said Hong.

The antenna structure of the telescope is scheduled to be finished by September 2012 and the facility is set to be used for tracking and locating missions during China's lunar probe program from 2013 to 2014.

China's Very Long Baseline Interferometry (VLBI), a type of astronomical interferometry used in radio astronomy would go up by 42 percent in terms of its sensitivity if the telescope replaces the current 25-meter one in Shanghai.

VLBI, composed of four telescopes in Shanghai, Beijing, Kunming, Urumqi and the data center in Shanghai was used for tracking and locating purposes during the first phase of China's lunar probe program."

 

[Martian2]

Photo taken at 21:46 on July 21, 2010 (local time) shows the sunset view taken from China's icebreaker "Xue Long" or "Snow Dragon". The Snow Dragon sailed to Chukchi Sea on Wednesday during polar day period. Chukchi Sea is a marginal sea of the Arctic Ocean. (Xinhua/Zhang Jiansong)

China begins 26th Antarctica season with a team of 251 scientists — MercoPress

"Wednesday, October 14th 2009 - 06:15 UTC
China begins 26th Antarctica season with a team of 251 scientists

Chinese scientists have set off from Shanghai for their 26th research mission to the Antarctic. The “Snow Dragon”, China's main research ship in the polar region, has gone through a series of maintenance and technical readjustments, according to Global Times.

China’s impressive icebreaker Xue Long or “Snow Dragon”

The new Antarctic season will last six months and cover a distance of more than 30,000 miles, the longest mission to date.

One of the main objectives of this season is collecting remains of meteorites and astronomic observation. The “Xue Long” carries a record 252 scientists and technicians including for the first time several from Taiwan. Russian and Australian scientists have also been invited.

A team of scientists will remain at the Zhongshan base in the bay of Prydz from where it will cover 400 kilometres to the Grove mountain range to collect as many meteorites as possible. China has the world’s third largest collection of meteorites.

Another team will land a the Kunlun base which is situated 7.3 kilometres southwest from the Argus summit, the highest point in Antarctica with 4,093 metres above sea level. The purpose is to install astronomic surveying equipment.

Two other teams will explore inland Antarctica.

China’s first Antarctic base, Changcheng (Great Wall) was established in 1985 south of King George island, and the second Zhongshan in 1989 south of the Prydz bay, in the Mirror peninsula east of the Larsemann hills.

“Kunlun” is the first Chinese base in continental Antarctica.

In the last 25 years China has completed 4,000 trips to the Southern Pole, according to the Chinese Institute of Polar Research.

“Xue Long” is expected back in Shanghai in late April 2010.

MV Xue Long, built originally as a polar cargo ship by Kherson Shipyard, Ukraine, on March 25, 1993, became the only research ice-breaker in China after elementary modification in 1994, for the Arctic and Antarctic regions. It is the re-supply vessel and the scientific research platform of the Chinese Arctic and Antarctic research expeditions. The vessel is 167 meters long and 22.6 meters beam, with the full-loaded draft of 9 meters, the full-loaded displacement of 21,250 tons, and the cruising radius of 12,000 nautical miles.

It is an A2-class ice-breaker with capability of breaking ice 1.2m (including 0.2m thick snow) at a sailing speed of 2 knots and can sail with the maximum speed of 17.9 knots, and also sail even during the weather of gale with more than 12 B scale.

The vessel has a data processing centre and seven laboratories with total area of 200 square meters and basic operating equipment on board of this vessel, including a low temperature sample storehouse, a low temperature cultivation room, a clean laboratory, a marine biological laboratory, a marine chemical laboratory, a geological laboratory, and a CTD winch, a biological winch, a geological laboratory, and a hallow-section device of EK-500 model.

Besides, 3 operating boats and a helicopter are equipped for the transportation and research purposes in the Arctic and Antarctic regions."

China's icebreaker sails among floe ice in the Chukchi Sea - Technology News - SINA English

China's icebreaker "Xue Long" or "Snow Dragon" sails among floe ice in the Chukchi Sea, July 22, 2010. The Snow Dragon encountered floe ice in the Chukchi Sea on Thursday. (Xinhua/Zhang Jiansong)

Chinese expedition team members get preparation for a helicopter on the deck of China's icebreaker "Xue Long" or "Snow Dragon", July 22, 2010. The Snow Dragon sailed to sea-ice field in the Chukchi Sea and a helicopter is sent to check floe ice condition. (Xinhua/Zhang Jiansong)

 

[Martian2]

LAMOST Progress : All the MB (spherical primary) segments are in place on June 19, 2008

China's LAMOST telescope in Xinglong, China

Heidi Newberg, Astronomy, Supernova, Dark energy, Careers Q&A, Naturejobs

"Published in Nature 466, 279 (7 July 2010) | 10.1038/nj7303-279a

Virginia Gewin

Heidi Newberg, a physicist and astronomer at Rensselaer Polytechnic Institute in Troy, New York, has won a National Science Foundation grant to create the first partnership between a US team and a Chinese-led astronomy project.

Were you always planning to become an astronomer?

No. I went to graduate school in the physics department at the University of California, Berkeley, but I didn't know what I wanted to study. After my first year, I got a job with the Berkeley Automated Supernova Search, analysing images. I had no background in astronomy and didn't even know what supernovae were, but it sounded interesting because it was unexplored and would make use of my analytical thinking skills. Later, I began working on the distant-supernovae search, which ultimately became Berkeley's Supernova Cosmology Project. The distant-supernovae search did not achieve success until after I had left and started my postdoc at Fermilab in Batavia, Illinois, but later versions of the search benefited from the wrong turns we made starting out. Eventually the data were used in the discovery that the Universe is accelerating. Those findings led to the idea of 'dark energy'. My career has been shaped by a theme — although projects can seem bleak at the start, continuing to work on them can lead to an important result.

How were supernovae found?

First we had to work out what was going wrong. We couldn't have done it without constant funding for the supernova group from the US Department of Energy at Lawrence Berkeley National Laboratory — there has to be a way to keep going long enough to get things to work. You need to learn from your mistakes. One thing we learned is that to find a supernova, you can't record images of the sky once, and come back the next year and expect things to be the same. Too many things in the sky change to be able to tell which objects are supernovae and which aren't. We learned to capture an image of the sky before and after a full Moon to get the best spectra for finding supernovae.

Describe how an early achievement helped to chart your career course.

As a graduate student, I had the task of redesigning a filter wheel that was part of an instrument for the Anglo-Australian Telescope, one of the first Southern Hemisphere telescopes to offer high-resolution and computer-controlled spectrographs. I hadn't worked on hardware. I didn't know anything about optics or filter wheels, but I talked to the engineers and got answers. It came together, but the challenges showed me that with projects that push the envelope of what is known and possible, you are going to have to learn new things.

How did you forge the partnership with China?

It came together from both sides. I had been analysing data from the Sloan Digital Sky Survey in Sunspot, New Mexico, but data collection ended in 2008. So I was looking for a new project. I was interested in working on the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) in Xinglong, China, because I wanted to continue with a galactic evolution project that I was exploring using Sloan data. But I needed data at a bigger scale, taking measurements on millions of stars. Using LAMOST I will have that, because it can take 4,000 spectra at once. I was also approached by the Chinese delegates as they talked to people involved in building Sloan, to learn how to make LAMOST successful. They contacted me because they wanted people to help them build the software.

What are the challenges in being a member of the first US team to join a Chinese-led astronomy project?

The Chinese structure for science is not similar to US or European structures. In China, individuals rather than teams are in charge. In US and European collaborations, committees are formed with representatives who have voting rights. It is like a democracy. With such different structures, it has been a challenge to define everyone's objectives, responsibilities and rights. The US National Science Foundation expects us to spell out the details in a proposal which might be funded up to a year later, whereas the Chinese organizations want to start working together and see how the relationship evolves, so there is a mismatch.

So have your goals changed?

No. No matter what the top layers look like, the scientists' expectations are similar. The challenge is getting the big organizations to recognize each other's systems rather than getting individuals to work together. I'll travel to China two to four times a year to make this programme a success.

What is your motto?

For the longest time, I told myself, “I can do anything”. When I turned 40, I realized that there are some things I simply can't do. Yet my motto got me pretty far before I figured that out."

 

[Martian2]

"Scientists Study Diamond Nitrogen Vacancy Materials for Quantum Computing Applications
2010-07-01

Since Richard Feynman's first envisioned the quantum computer in 1982, there have been many studies of potential candidates -- computers that use quantum bits, or qubits, capable of holding an more than one value at a time and computing at speeds far beyond existing silicon-based machines for certain problems. Most of these candidate systems, such as atoms and semiconducting quantum dots, work for quantum computing, but only at very low temperatures.

Now a team of researchers from the Wuhan Institute of Physics and Mathematics, the Chinese Academy of Sciences and the Hefei National Laboratory for Physical Sciences at the Microscale at the University of Science and Technology of China has made a step toward a warmer solution.

As reported in the journal Applied Physics Letters, the team is exploring the capabilities of diamond nitrogen vacancy (NV) materials. In this material, a "molecule" at the heart of an artificially created diamond film consists of a nitrogen atom (present as in impurity amid all those carbon atoms) and a nearby vacancy, a place in the crystal containing no atom at all. These diamond structures offer the possibility of carrying out data storage and quantum computing at room temperature.

One of the challenges of this technology is the difficulty of coupling two of the NV centers in separate nanocrystals of diamond. To make a quantum computer, many diamond-NV centers need to be coupled (made quantum coherent with each other), encoding the information in each, and operations based on their interactions (or couplings) must be undertaken. Mang Feng of the Wuhan Institute of Physics and Mathematics of the Chinese Academy of Sciences and his collaborators present an idea that could lead to a quantum mechanical coupling of these NV centers, called entanglement. This proof of principle is now ready to be extended to multiple operations, which is by no means a simple accumulation of the operations.

"Our research is another step in realizing the potential of the long-envisioned quantum computers with techniques available currently or in the near-future," states Dr. Feng, "Continued advances could stimulate further exploration in condensed matter physics, quantum information science and diamond making technology."


More information: The article, "One-step implementation of multi-qubit conditional phase gating with nitrogen-vacancy centers coupled to a high-Q silica microsphere cavity" by Wan-li Yang et al will appear in the journal Applied Physics Letters. See: //apl.aip.org/(Provided by American Institute of Physics)"

[Note: Thank you to "lkjhgfdsa" for finding this story.]

 

[Martian2]

Ministry of Science and Technology of the People's Republic of China

"Superconductivity Found in One-Atomic-Layer

Not long ago, a study, led by XUE Qikun, CHEN Xi, and JIA Jinfeng at Tsinghua University Dept. of Physics, in collaboration with a team headed by MA Xucun with the Chinese Academy of Sciences Institute of Physics, Prof. WANG Yayu, Tsinghua University Dept. of Physics, Prof. LIN Haiqing at the Chinese University of Hong Kong, and Prof. LIU Ying of the Pennsylvania State University Department of Physics and Material Research Institute, has found superconductivity in one-atomic-layer metal films grown on Si substrates. One-atomic-layer is the ultimate thickness a practical material can reach. The finding, published in the recent online issue of Nature Physics, renders a solution to the question concerning how thin a superconductor can be."

Superconductivity: One layer is enough : featured highlight : NPG Asia Materials

"Superconductivity: One layer is enough
NPG Asia Materials featured highlight | doi:10.1038/asiamat.2010.78
Published online 24 May 2010

Superconductivity has been observed in films as thin as one atomic layer.

Fig. 1: Scanning tunneling microscope image of a single atomic layer of lead (in the striped incommensurate phase) on silicon (image size is 50 nm × 50 nm).

Superconductivity is a fascinating phenomenon. The signatures of superconductivity, such as its vanishing electrical resistance and expulsion of a magnetic field, as well as its potential for diverse applications, have intrigued scientists for decades.

Nowadays, as low temperature ‘standard’ superconductors become better understood, attention has begun to focus on complex high-temperature superconductors. It is accepted that in these materials, lattice vibrations (referred to as phonons) mediate the formation of electron pairs, which is essential for the emergence of a superconducting phase. However, despite this recent trend in research, standard superconductors can still present intriguing results, as shown by Qi-Kun Xue and colleagues who have demonstrated that superconductivity can be observed even in single atomic layers of lead and indium1.

Two-dimensional (2D) superconductivity is a rather fragile state of matter. It is therefore natural to wonder what is the minimum thickness needed to observe this phenomenon, or whether a single layer of ordered metal atoms, which represents the ultimate 2D limit of a crystalline film, could be superconducting. The team studied single-layer films of lead (Fig. 1) and indium grown on Si(111). Using scanning tunneling spectroscopy at high energy resolution, they observed a region of zero conductance for low applied voltage, terminated on each side by sharp peaks — the signature of superconductivity. Furthermore, the films exhibited vortices when a magnetic field was applied, confirming the existence of a superconducting phase.

Through angular-resolved photoemission spectroscopy, the team found that for each metal the electron–phonon coupling was greatly enhanced with respect to the bulk case. This implies that the covalent silicon–metal bonding has a strong role in providing the mechanism for electron pairing, while the metal itself mainly provides the necessary carriers.

“Our work sheds new light on the mechanism of superconductivity at reduced dimensionality, especially the crucial role played by the interface,” says Xue. “The tunable atomic and electronic structures in these well-defined 2D materials provide an ideal platform for testing various theoretical models when dealing with 2D many-body physics. In addition, the exploration of one-atomic-layer superconductors grown on silicon may also help to develop superconducting electronic circuits compatible with silicon technology.”

Reference

1. Zhang, T.,1,2 Cheng, P.,1 Li, W.-J.,2 Sun, Y.-J.,1 Wang, G.,1 Zhu, X.-G.,1 He, K.,2 Wang, L.,2 Ma, X.,2 Chen, X.,1* Wang, Y.,1 Liu, Y.,3 Lin, H.-Q.,4 Jia, J.-F.1 & Xue, Q.-K.1,2* Superconductivity in one-atomic-layer metal films grown on Si(111). Nature Phys. 6, 104 (2010). | article

Author affiliation

1. Key Lab for Atomic and Molecular Nanoscience, Department of Physics, Tsinghua University, Beijing 100084, China
2. Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
3. Department of Physics and Material Research Institute, Pennsylvania State University, Pennsylvania 16802, USA
4. Department of Physics, The Chinese University of Hong Kong, Hong Kong, China
*Email: xc@mail.tsinghua.edu.cn

This research highlight has been approved by the author of the original article and all empirical data contained within has been provided by said author."

 

[Martian2]

Ministry of Science and Technology of the People's Republic of China

"Strong Crystal Size Effects on Deformation Twinning

Under the guidance of her tutor, YU Qian, a post-graduate at Xi’an Jiaotong University State Key Laboratory for Mechanical Behavior of Materials, in collaboration with Prof. LI JU with University of Pennsylvania Department of Materials Science and Engineering, and Dr. HUANG Xiaoxu of Technical University of Denmark Laboratory for Sustainable Energy, made an in-depth study of the deformation twinning behavior of nano-sized metal crystals and its impact on the dynamic performance of the materials. YU and coworkers found that the size of monocrystals is of a strong effect on the dynamic performance. The finding, published in the recent issue of journal Nature, provides a meaningful insight of materials performance evaluation and design; especially on material processing at the nano-scale utilizing the strong crystal size effect."

Nanomechanics: Size matters : research highlight : NPG Asia Materials

"Nanomechanics: Size matters
NPG Asia Materials research highlight | doi:10.1038/asiamat.2010.56
Published online 12 April 2010

The deformation mechanism of single-crystal nanopillars has been shown to change dramatically at dimensions below one micrometer.

Fig. 1: A scanning electron microscopy image of a nanopillar made from a single-crystal of titanium after it has been inelastically deformed.

Reproduced from Ref. 1 (copyright); J. Sun, J. Li

As electronic devices continue to shrink in size, it is becoming increasingly important to understand mechanical deformation at microscopic scales. Inelastic deformation — a type of deformation that persists even after an applied force is removed — can lead to device failure and occur primarily through two mechanisms: deformation twinning and ordinary dislocation plasticity. The mechanism that is activated depends on whether deformations across the sample are correlated.

The origins of deformation twinning are poorly understood, as is the dependence of this mechanism on size. Now, a team of scientists from China, the US and Denmark, led by Jun Sun at Xi’an Jiaotong University and Ju Li at the University of Pennsylvania, have demonstrated that deformation twinning is completely suppressed in nanocrystals below a critical size[1].

The researchers studied the deformation of pillars made from a single crystal of a titanium alloy using compression tests. Some of the tests were conducted while the sample was being observed by transmission electron microscopy. They found that when the pillars had a diameter of less than one micrometer, deformation twinning no longer occurred. This is in sharp contrast with bulk deformation of the same alloy, which is dominated by deformation twinning, which, it turns out, is more dependent on size than the action of dislocation plasticity.

Sun, Li and their colleagues consider this strong dependence on size to arise from the collective nature of deformation twinning. Correlated deformations occur when strongly coupled defects catalyze the slip of adjacent crystal planes past one another. As the pillar diameter is reduced, defect coupling and twinning are both suppressed, leaving dislocation plasticity as the dominant mechanism for sufficiently small samples.

“The research is in its early stages,” Sun says. “It is still quite fundamental, and the connection to new technologies cannot be known with certainty at the moment.” At the same time, however, micrometer-sized pillars are commonly encountered in a range of applications, suggesting that these findings could be relevant to many devices, including micro- and nano-electromechanical systems. Future work will involve the use of high-quality electron microscopy to better understand how crystal planes slip past each other.

Reference

1. Yu, Q.,1 Shan, Z.-W.,1,2 Li, J.,3 Huang, X.,4 Xiao, L.,1 Sun, J.1 & Ma, E.1,5 Strong crystal size effect on deformation twinning. Nature 463, 335 (2010). | article

Author affiliation

1. Center for Advancing Materials Performance from the Nanoscale (CAMP-Nano), State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an, 710049, China
2. Hysitron Incorporated, Minneapolis, Minnesota 55344, USA
3. Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
4. Danish-Chinese Center for Nanometals, Materials Research Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark, DK-4000 Roskilde, Denmark
5. Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
*Email: junsun@mail.xjtu.edu.cn

This research highlight has been approved by the author of the original article and all empirical data contained within has been provided by said author."

 

[Martian2]

Chemical sensing: Collapsing for chirality : featured highlight : NPG Asia Materials

"Chemical sensing: Collapsing for chirality
NPG Asia Materials featured highlight | doi:10.1038/asiamat.2010.147
Published online 13 September 2010

An organometallic gel undergoes a dramatic change in structure in the presence of molecules with specific structural configurations.

Fig. 1: Electron microscopy images of the dried gel (left) and solution (right) forms of binaphthol–copper.

From Ref. 1. Reproduced with permission. (copyright) 2010 ACS

One of the fastest ways to qualitatively analyze chemical reactions is visually; it’s hard to mistake an abrupt color change or the appearance of new precipitates in a solution. These methods, however, are restricted to only a few processes, and normally do not provide an understanding of advanced phenomena such as chirality — the tendency for certain compounds to occur in mirror-image forms. The two chiral forms, called left- and right-handed enantiomers, can have very different properties, such as pharmaceutical effects. Yet physically, the two forms can only be distinguished through specialized and time-consuming techniques.

Researchers led by Xiao-Qi Yu from Sichuan University in China and Lin Pu from the University of Virginia in the USA[1] have now discovered an innovative system that allows chirality to be detected visually. Their method involves a gel that collapses when it interacts with enantiomers of opposite ‘handedness’.

Molecular gels have recently gained attention as sensing platforms because their structures at the boundary between liquid and solid states are extremely responsive to changes in their environment. Originally, Yu, Pu and their colleagues had been studying the reaction between a derivative of binaphthol — a chiral aromatic compound — and copper to develop a fluorescent sensor. But when the binaphthol derivative was mixed with copper ions in an ultrasonic bath, an opaque green gel quickly formed. The formation of such a gel was unexpected because ultrasound usually breaks up gel networks.

The team found that their gel consisted of a stabilized three-dimensional network (Fig. 1). Because chiral compounds such as binaphthol act differently when mixed with other chiral substances, the researchers decided to investigate the gel’s stability towards chiral amino alcohols — molecules known to displace copper from aromatic binding sites.

Pu and his colleagues found that the binaphthol–copper gel was particularly sensitive to enantiomer type. When the gel and the amino alcohol had the same chirality, the gel remained stable even after ultrasonication. If the chiral sites were different, however, the gel collapsed as soon as it was agitated.

The researchers are now working on fully understanding the mechanism behind their collapsible detection system. “This will allow us to develop new gel materials for recognition of diverse chiral molecules with rapid assays,” says Pu.

Reference

1. Chen, X.,1 Huang, Z.,1 Chen, S.-Y.,1 Li, K.,1 Yu, X.-Q.1 & Pu, L.2* Enantioselective gel collapsing: A new means of visual chiral sensing. J. Am. Chem. Soc. 132, 7297 (2010). | article

Author affiliation

1. Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
2. Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904-4319, USA
*Email: lp6n@virginia.edu

This research highlight has been approved by the author of the original article and all empirical data contained within has been provided by said author."


Color-change in a chemical reaction is a very useful tool in chemistry. Scientists rely on color-change in titration experiments all of the time. The latest discovery, from Chinese scientists in visually detecting the "handedness" of an enantiomer through "chemical sensing: collapsing for chirality," is a great boon to all scientists.

Titration endpoint color change

 

[Martian2]

Carbon nanotubes: The domino effect : research highlight : NPG Asia Materials

"Carbon nanotubes: The domino effect
NPG Asia Materials research highlight | doi:10.1038/asiamat.2010.158
Published online 27 September 2010

Carbon nanotube structures can be mechanically oscillated via a temperature-induced ‘domino’ process.

Fig. 1: Temperature changes induce waves of domino-like, reversible structural transformations in carbon nanotubes.

Adapted from Ref. 1. Reproduced with permission. (copyright) 2010 ACS

Ultra-tiny heat engines that convert thermal energy into mechanical energy may soon be on the horizon according to a computer simulation study from China[1]. Tienchong Chang and Zhengrong Guo from Shanghai University report that carbon nanotubes can be changed from their usual circular shapes into collapsed, flattened structures through a domino-like wave that propagates along the length of the tube. This transformation can be reversed by raising the temperature; setting the stage for multifunctional oscillators that operate at molecular levels.

Calculations by Chang previously showed that the circular structures of large single-walled carbon nanotubes are only meta-stable: energetically, the tube is most stable when it collapses and lies flat. Transitioning to this fallen state, however, requires overcoming a significant energy barrier. “If we view each carbon ring along the nanotube as a domino, then the stable state corresponds to a fallen-down system, while the meta-stable circular state is when the domino is standing up,” says Chang. “A standing domino cannot fall down by itself — it needs an external stimulus.”

The researchers found that clamping down on one end of the nanotube provided the necessary impetus to release the material’s potential energy; sequentially knocking the carbon structure down like a wave of tumbling dominoes. The next challenge facing the team was how to control this effect.

Molecular dynamic simulations on a 4.3 nm-wide tube with one end shut and the other propped open revealed that temperature could modify the material’s stable state. After the tube structure toppled over at room temperature, raising the temperature to over 600 degrees Celsius reversed the transformation: the collapsed zone shrank along the tube as the carbon rings returned to their upright, circular shapes (Fig. 1).

Additional simulations showed that the critical temperature needed to induce the conversion between the two states was a linear function of tube diameter, with larger tubes needing higher temperatures to leave the collapsed state. The speed of the propagating domino waves, which can reach 800 m/s, could also be adjusted through subtle temperature variations.

Chang notes that the highly tunable nature of the temperature-induced domino effect opens the door to many novel applications, including rechargeable ‘nanoguns’ that can controllably expel molecules or particles from the tubes.

Reference

1. Chang, T.* & Guo, Z. Temperature-induced reversible dominoes in carbon nanotubes. Nano Lett. 10, 3490 (2010). | article

Author affiliation

Shanghai Institute of Applied Mathematics and Mechanics, Institute of Low Dimensional Carbon and Device Physics, Shanghai University, Shanghai 200072, China
*Email: tchang@staff.shu.edu.cn

This research highlight has been approved by the author of the original article and all empirical data contained within has been provided by said author."

 

[Martian2]

Electrochemistry: Long live the lithium battery : Article : Nature China

"Electrochemistry: Long live the lithium battery
Published online: 1 September 2010 | doi:10.1038/nchina.2010.99
Felix Cheung

Eliminating oxygen in the electrolyte prolongs the life of a lithium-ion battery

Original article citation
Luo, J. Y., Cui, W. J., He, P. & Xia, Y. Y. Raising the cycling stability of aqueous lithium-ion batteries by eliminating oxygen in the electrolyte. Nature Chem. doi:10.1038/nchem.763 (2010).

© (2010) istockphoto.com/Ingenui

Non-aqueous electrolytes of traditional lithium-ion batteries use highly toxic and flammable organic solvents, which can be dangerous if used improperly. Using aqueous electrolytes can avoid this problem, but an aqueous lithium-ion battery typically loses half of its battery capacity after 100 charge–discharge cycles. Yongyao Xia and co-workers at Fudan University in Shanghai[1] have now devised several strategies to prolong the lifetimes of such aqueous batteries.

A battery loses capacity when its electrodes oxidize and internal resistance increases. The researchers analysed the stability of electrode materials in aqueous electrolytes and found that negative electrodes react with water and oxygen during discharge, which causes capacity fading upon charge–discharge cycling. They improved the stability of aqueous lithium-ion batteries by eliminating oxygen, adjusting the pH of the electrolyte and using carbon-coated electrode materials. The capacity retention of their batteries was over 90% after 1,000 cycles.

By implementing these strategies, aqueous lithium-ion batteries may offer an energy-storage system with high safety, low cost and long lifetime.

The authors of this work are from:
Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Institute of New Energy, Fudan University, Shanghai, China.

Reference

1. Luo, J. Y., Cui, W. J., He, P. & Xia, Y. Y. Raising the cycling stability of aqueous lithium-ion batteries by eliminating oxygen in the electrolyte. Nature Chem. doi:10.1038/nchem.763 (2010). | Article"

 

[mughaljee]

well done china.

 

[Mani2020]

This is slap on the face of those people who always degraded chinese tech ,always laughed on chinese achievements and made fun of them .this will prove the world how rapidly China is developing in every field

Congrats to CHINA