News on China's scientific and technological development.

Metallic glasses: Down to the wire



"Metallic glasses: Down to the wire
NPG Asia Materials featured highlight | doi:10.1038/asiamat.2011.23
Published online 14 February 2011

Glassy metallic wires can be controllably manufactured by drawing from a supercooled rod


Photograph of a thin, flexible metallic glass fiber (left) and an electron microscopy image of a metallic glass rope weaved from such fibers (right).

The metals we are most familiar with adopt a periodic, crystalline atomic arrangement. Metallic glasses, on the other hand, have an amorphous structure that is well suited for certain fabrication processes such as casting. Glassy metallic wires with widths of micrometers or nanometers are also less brittle than their bulk metallic counterparts, but such wires have proved difficult to fabricate. Wei Hua Wang and colleagues from the Chinese Academy of Sciences in Beijing have now developed a simple method for producing well-controlled and defect-free metallic glass wires[1].

An ideal fabrication process for such wires should be able to produce narrow wires with uniform surfaces that are free of defects, and should also be applicable to a wide variety of starting materials. Existing methods have not been able to satisfy all of these requirements simultaneously, often because they involve a foreign material, for cooling or filling, that comes in contact with the wires during fabrication.

Wang and his colleagues developed a method that avoided such contact by placing a bulk metallic glass rod inside a steel cylinder, which was then heated by a magnetic induction coil. The rod was heated rapidly from a solid to a ‘supercooled’ liquid state—meaning that it became liquid despite being heated to below its melting point. An ultrathin wire could then be drawn from the low-viscosity liquid using a suspended weight or a rotating shaft.

The researchers found that the resulting wires had high structural uniformity. Their surfaces were as smooth as those of industrial silica glass fibers, and the wires could tolerate a much greater bending angle, in excess of 90° (see image). The diameters of the wires were easily controlled by adjusting the drawing force, allowing the researchers to draw wires as thin as 70 nm—ten times thinner than any wires produced previously.

This work increases the feasibility of using metallic glass fibers as building blocks for microscale and nanoscale devices, with possible applications in composites, sensors, intelligent fabrics, circuit interconnects and optical waveguides. It also holds considerable intrinsic scientific interest, says Wang. “Our fibers can be used as a model system to study many fundamental issues in metallic glasses.”

Reference

1. Yi, J., Xia, X. X., Zhao, D. Q., Pan, M. X., Bai, H. Y., & Wang, W. H. Micro-and nanoscale metallic glassy fibers. Adv. Eng. Mater. 12, 1117 (2010). |

Author affiliation

Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China"

Surface chemistry: A close look at hydrophobicity



"Surface chemistry: A close look at hydrophobicity
NPG Asia Materials research highlight | doi:10.1038/asiamat.2011.25
Published online 14 February 2011

Direct 3D imaging of the interface between water and a superhydrophobic surface provides insights with potential industrial applications.


Confocal laser scanning microscopy images and schematic diagrams showing the state of a water droplet on a superhydrophobic surface.

A water droplet on a hydrophobic surface can adopt one of two states: a ‘Wenzel’ state in which the droplet makes intimate contact with the rough ups and downs of a surface, or a ‘Cassie’ state in which the droplet sits high on top of the peaks. The Cassie state is of particular interest in the development of superhydrophobic surfaces—like the surface of a lotus leaf—for industrial applications such as self-cleaning surfaces. Observing these two states directly, however, has proved to be remarkably difficult. Jian Wang and colleagues at the South China University of Technology and the Shanghai Institute of Applied Physics in China have now obtained three-dimensional images of the interface between water and a hydrophobic surface and observed the transition between the Wenzel and Cassie states in real time[1].

Using a technique known as confocal laser scanning microscopy, the team observed the buried contact between a droplet and a superhydrophobic surface prepared from carbon nanotubes and Nafion, an ionic polymer. Their microscopy technique revealed 10 μm-thick pockets of air between the droplet and the surface—evidence of the Cassie state. It is the trapped air that produces the superhydrophobic state, allowing the droplet to roll easily off the surface. Using ultrasound or by adding a surfactant, the researchers were able to trigger and image the transition from the Cassie state through a mixed-state to the Wenzel state in real time (see image), providing valuable insight into the mechanism of superhydrophobicity.

Wang and his colleagues plan to build on the success of the current study and continue to explore interactions on various surfaces to gain a further understanding of the underlying mechanisms. The ability to actively control the state of water on a surface could have a range of applications in the fields of superhydrophobic materials, microchannel flow and protein folding. “We like to explore natural processes and apply our knowledge to industrial processes,” says Wang. “The understanding of natural phenomena, which satisfies our intellectual development, is as important as the technical advances that may help people live a better life.”

Reference

1. Luo, C.1,2, Zheng, H.1, Wang, L.1, Fang, H.2, Hu,J.2, Fan, C.2, Cao, Y.1 & Wang, J.1 Direct three-dimensional imaging of the buried interfaces between water and superhydrophobic surfaces. Angew. Chem. Int. Ed. 49, 9145 (2010). |

Author affiliation

1. Key Laboratory of Specially Functional Materials, Ministry of Education, Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou 510640, China

2. Laboratory of Physical Biology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China"

Smart fluids: Switchable viscosity



"Smart fluids: Switchable viscosity
NPG Asia Materials featured highlight | doi:10.1038/asiamat.2011.29
Published online 21 February 2011

Stimuli-responsive ‘smart fluids’ reversibly change viscosity with pH.


Photographs and transmission electron microscopy images showing the formation of a clear, highly viscous micellar liquid at lower pH (left), and the collapse of that structure to form a cloudy, watery liquid at higher pH (right).

Materials that change in some way in response to external stimuli are generating considerable interest for a range of potential industrial uses. Such ‘smart’ materials offer the possibility of creating systems that can react to light or electric current, but the smart systems developed to date typically rely on complex, costly molecules that tend to react too slowly for practical applications. Zonglin Chu and Yujun Feng at the Chengdu Institute of Organic Chemistry in China have now developed a low-cost smart material that undergoes rapid changes in viscosity in response to variations in pH[1].

Under acidic conditions, the smart fluid developed by the research team is a thick, viscoelastic liquid. On the addition of an alkali solution, however, the fluid begins to flow like water within just seconds. The system is based on a molecule that is cheap, simple to produce and easy to separate from the fluid for reuse.

The smart behavior was achieved by combining maleic acid with a specially structured long-chain molecule called UC22AMPM. Under acidic conditions, the UC22AMPM molecules aggregate into long worm-like arrays or ‘micelles’ with surface charge, making the fluid viscous. As the pH rises with the addition of alkali species to the system, the network falls apart and the fluid becomes highly liquid.

The ability for a system to change viscosity in response to pH could be of particular interest to the oil industry, says Feng. A process called ‘acidization’ is often employed in the industry to stimulate oil wells by pumping a thick acidic solution down a well to crack any carbonate rock that is blocking the flow of oil. As the acid reacts with the rock, the pH rises—the smart fluid developed by Chu and Feng would become a watery liquid that could carry any dissolved rock back to the surface.

As well as developing this fluid further for the specific application of oil well stimulation, Feng says the next step will be to make the system more adaptable. “Our current work is focused on multi-responsive micellar systems that could be triggered by pH, temperature, salinity or light—or combinations of these stimuli,” he says.

Reference

1. Chu, Z.1,2 & Feng, Y.1 pH-switchable wormlike micelles. Chem. Commun. 46, 9028 (2010). |

Author affiliation

1. Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, China

2. Graduate School of the Chinese Academy of Sciences, Beijing 100049, China"

Physicists Discover Quantum Law of Protein Folding



"Physicists Discover Quantum Law of Protein Folding
Quantum mechanics finally explains why protein folding depends on temperature in such a strange way.
kfc 02/22/2011



The famous Arrhenius relationship states that things happen faster as they got hotter. In chemistry, that's generally true but there's an important exception: the speed at which proteins fold into their functional shape.

It's easy to think that proteins ought to fold more quickly as they cool down and then unfold more quickly as they heat up. But the actual relationship is both nonlinear and asymmetric, meaning that unfolding is not the reverse of folding.

Molecular biologists have put forward various mechanisms to explain this, such as the nonlinear interaction between water and hydrophobic parts of proteins. But none of these are very convincing.

That looks set to change with the work of Liaofu Luo at the Inner Mongolia University and Jun Lu at the Inner Mongolia University of Technology, both in China. They say that the way folding depends on temperature all becomes clear as soon as you take quantum mechanics into account.

First, a little background on protein folding. Proteins are long chains of amino acids that become biologically active only when they fold into specific, highly complex shapes. The puzzle is how proteins do this so quickly when they have so many possible configurations to choose from.

To put this in perspective, a relatively small protein of only 100 amino acids can take some 10^100 different configurations. If it tried these shapes at the rate of 100 billion a second, it would take longer than the age of the universe to find the correct one. Just how these molecules do the job in nanoseconds, nobody knows.

What they do know, however, is that the rate at which they fold is highly sensitive to temperature and biologists have a significant amount of data showing exactly how these rates vary. Plotting these data leads to various unexpected curves.

Today, Luo and Lo say these curves can be easily explained if the process of folding is a quantum affair. By conventional thinking, a chain of amino acids can only change from one shape to another by mechanically passing though various shapes in between.

But Luo and Lo say that if this process were a quantum one, the shape could change by quantum transition, meaning that the protein could 'jump' from one shape to another without necessarily forming the shapes in between.

Luo and Lo explore this idea using a mathematical model of how this would work and then derive equations that describe how the rate of "quantum folding" would change with temperature. Finally they fit the predictions of their model to some real world experiments.

Their astonishing result is that this quantum transition model fits the folding curves of 15 different proteins and even explains the difference in folding and unfolding rates of the same proteins.

That's a significant breakthrough. Luo and Lo's equations amount to the first universal laws of protein folding. That's the equivalent in biology to something like the thermodynamic laws in physics.

Impressive stuff. And don't expect it to end here.

Various groups are finding evidence of quantum processes at work in everything from photosynthesis to bird navigation.

If quantum mechanics plays a key role in protein folding, then there can be little question of its importance in the workings of other cellular machines. It can only be a matter of time before the floodgates open for quantum biologists.

Ref: : Temperature Dependence of Protein Folding Deduced from Quantum Transition"

AMD chooses TSMC and ignores AMD-spinoff Global Foundries!


A 12-inch wafer is displayed at Taiwan Semiconductor Manufacturing Company in Xinchu, Taiwan. (Photo: REUTERS / Richard Chung)



"AMD plans exclusive Southern Islands TSMC contract
Increases production for Zacate China launch
22 Feb 2011 09:55 | by Hector Dish | posted in Chips

TSMC really must be rolling in it. Taiwan Semiconductor Manufacturing Co. enjoys lucrative contracts from heaps of chip outlets where it makes fiscal sense to outsource production, and AMD has just, reportedly, expanded its lines.

AMD has signed the papers to book further capacity for its 40nm Zacate and Ontario APUs, as it readies itself to storm China. As TechEye reported last year, the demand is so strong that everyone wants a piece and AMD needs to make sure it has the means to plug that need.

Taiwan Economic News reports according to sources close to AMD, it wants to sign up all new capacities TSMC is planning to add to its Fab 12 and Fab 14 factories this year so it can begin the roll-out, starting in Beijing this March. AMD's Llano 32nm is still penned for GloFo production, but it has been talking up TSMC behind the scenes for some time.

Sources familiar with the matter suggest that AMD also wants to give TSMC the exclusive contract for the upcoming 28nm Southern Islands chip early 2012.

Likewise, when Samsung began kicking up a storm with its own tablets and smartphones, direct competitor Apple is reportedly considering a TSMC contract for CPUs, seeking a neutral manufacturer for the mysterious second generation iPad."



"AMD's Fusion Chips In Tight Supply - Report.

AMD Boosts Orders to TSMC as Demand Exceeds Supply
[02/21/2011 11:19 PM]
by Anton Shilov

Advanced Micro Devices has boosted orders for its Fusion processors based on Bobcat micro-architecture to Taiwan Semiconductor Manufacturing Company. Apparently, demand towards low-power Fusion chips at present is exceeding supply.

Due to shortages of Fusion accelerated processing units - which integrate one or two x86 cores based on Bobcat architecture and DirectX 11-supporting ATI Radeon HD 6000-class graphics processing units along with memory controller and additional special-purpose hardware - AMD's C- and E-series APUs code-named Ontario and Zacate are hard to find in Europe and the U.S., reports DigiTimes web-site citing Commercial Times news-paper.

It is unclear how many more APUs the Sunnyvale, California-based designer of microprocessors and graphics chips ordered from TSMC. However, it is reported that AMD hopes to "secure all new capacity from TSMC's 300mm fab, Fab 14's phase 4 facilities to solve the shortage issue".

For about 1.5 months in 2010 AMD managed to sell around a million of its Fusion APUs. The number is hardly too high and it is not surprising that the chips are in tight supply given the fact that many netbook and mainboard makers have introduced their products based on the C- and E-series APUs.

AMD and TSMC did not comment on the news-story."

China-Kazakhstan high-speed railway contract sealed


Kazakhstan purchases "1,050-kilometer-long double-track" high-speed-rail line from China.



"China-Kazakhstan high-speed railway contract sealed
08:39, February 23, 2011

China and Kazakhstan will jointly build a high-speed railway connecting the central Asian nation's cities of Astana and Almaty, with the project to be completed in 2015, Askar Mamin, the president of Kazakhstan Railways, said yesterday in Beijing.

Trains on the 1,050-kilometer-long double-track planned line connecting Kazakhstan's capital Astana with its biggest city Almaty will run at a maximum speed of 350km per hour, serving 5 million passengers annually, said Mamin, adding that a memorandum of understanding has been signed with China's railways. The line will use the most advanced Chinese technology and new-generation locomotives and cars.

Kazakhstan President Nursultan Nazarbayev arrived in Beijing on Monday for a three-day state visit.

The two nations also signed a contract worth several billion dollars for long-term Kazakhstan supplies of uranium to China, part of a cooperation program with Guangdong Nuclear Power Co, Kazakhstan's Samruk-Kazyna National Welfare Fund Chairman Kairat Kelimbetov told the Kazinform news agency.

Source: Shanghai Daily/Agencies

The two sides also agreed on a US$1 billion plan for the Export-Import Bank of China to finance construction of an oil refinery in the Kazakh city of Atyrau, Kelimbetov said.

Source: Shanghai Daily"

Note: Thank you to "Marchpole" for the post.

‘Walking Cactus’ Called Missing Link for Insects



"‘Walking Cactus’ Called Missing Link for Insects
by Wynne Parry, LiveScience Senior Writer
Date: 23 February 2011 Time: 01:01 PM ET


Fossils from an extinct creature, dubbed a walking cactus, may reveal a piece of arthropod history in their jointed legs.
Jianni Liu

Fossils of a 10-legged wormy creature that lived 520 million years ago may fill an important gap in the history of the evolution of insects, spiders and crustaceans.

The so-called walking cactus belongs to a group of extinct worm-like creatures called lobopodians that are thought to have given rise to arthropods. Spiders and other arthropods have segmented bodies and jointed limbs covered in a hardened shell.

Before the discovery of the walking cactus, Diania cactiformis, all lobopodian remains had soft bodies and soft limbs, said Jianni Liu, the lead researcher who is affiliated with Northwest University in China and Freie University in Germany.

"Walking cactus is very important because it is sort of a missing link from lobopodians to arthropods," Liu told LiveScience. "Scientists have always suspected that arthropods evolved from somewhere amongst lobopodians, but until now we didn't have a single fossil you could point at and say that is the first one with jointed legs. And this is what walking cactus shows."

Leggy find

Liu and other researchers described the extinct creature based on three complete fossils and 30 partial ones discovered in Yunnan Province in southern China. The walking cactus had a body divided into nine segments with 10 pairs of hardened, jointed legs, and it measured about 2.4 inches (6 centimeters) long.

It's not clear how the leggy worm made its living. It could have used its tube-like mouth called a proboscis to suck tiny things from the mud, or it may have used its spiny front legs to grab prey, Liu said.

Clues to arthropod evolution are preserved in modern-day velvet worms, which are considered the only living relative to all arthropods. Once mistaken for slugs, these land-dwelling worms are almost entirely soft-bodied except for hardened claws and jaws.

Where spiders, insects and others came from

The discovery of the walking cactus helps fill in the evolutionary history between the velvet worms and modern arthropods, which, in terms of numbers and diversity, are the most dominant group of animals on the planet, according to Graham Budd, a professor of paleobiology at Uppsala University in Sweden, who was not involved in the current study.

The walking cactus is the first and only case of hardened, jointed limbs built for walking appearing in a creature that is not recognizable as an arthropod, Budd said.

But Budd is not convinced that, as the researchers argue, the walking cactus's hardened legs were passed directly down to modern arthropods.

"I am not persuaded that it is a direct ancestor or as closely related to living arthropods as they suggest," he told LiveScience. "I would like to see more evidence; the great thing is a lot more material keeps coming up."

For instance, it is possible that the walking cactus is less closely related to modern arthropods, and that hardened legs evolved multiple times. It is also possible that the bodies of primitive arthropods hardened before their legs did, Budd said.

New fossils, particularly from China, have helped clarify the evolutionary history of arthropods, and in the last decade or so, scientists have come to more consensus regarding that history, he added."

Nanowires


A SEM (scanning electron microscope) image of epitaxial nanowire heterostructures grown from catalytic gold nanoparticles.



"Nanowire research at Stevens makes cover of Applied Physics Letters
February 23, 2011

An article by Stevens Institute of Technology researchers featured as the cover page of Applied Physics Letters Volume 98, Issue 7 represents a step forward in techniques for the arrangement of nanowires.

Professors Dr. Chang-Hwan Choi and Dr. Eui-Hyeok (EH) Yang, and graduate students Wei Xu, Rajesh Leeladhar, and Yao-Tsan Tsai, focused on nanowires, structures that are mere nanometers in diameter but have enormous potential in nanotechnology to create tiny circuits that would make possible nanoelectronics, nanophotonics, and nanobiotechnology. Such devices could forever change the way we harness energy, communicate, and treat disease.

"This highly promising research can lead to the development of reliable nano-actuators which in turn stand to benefit fields and applications as diverse as biomaterials, nano robots, artificial muscles, and high frequency nano antenna applications and is an affirmation of the cutting edge research that is taking place in the Micro/Nano Devices Laboratory," says Dr. Constantin Chassapis, Deputy Dean of the Charles V. Schaefer, Jr. School of Engineering and Science and Department Director of Mechanical Engineering.

The precise arrangement of nanowires on a large scale is crucial for any practical application. However, many current techniques for the controllable arrangement of nanowires suffer limitations.

The article, entitled, "Evaporative self-assembly of nanowires on superhydrophobic surfaces of nanotip latching surfaces," reports a technique that is highly effective in assembling nanowires. A colloid droplet of nanowires (i.e., nanowires dispersed in a water droplet) is placed on a nano-engineered superhydrophobic surface. As the droplet evaporates, two forces cause the nanowires to self-assemble on the specially-designed surface: hydrodynamic forces inside the droplet and capillary forces of the receding contact line of the droplet. Simple and convenient, the new self-assembly technique offers a high yield rate, improving the controlled arrangement of nanowires which may be used in nanodevices."

China's new 400 km/h (or 248 mph) high-speed train


China unveils the CRH 400A (stands for 400 km/h)






China's CRH 400A manufacturing facility

Note: Thank you to "Marchpole" for the pictures.

Re: China's new 400 km/h (or 248 mph) high-speed train

I like the color scheme. It's refreshing.