Superconductivity: One layer is enough
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 indium[1].
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."
----------
Nanomechanics: Size matters
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 © 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."
----------
China starts up first fourth-generation nuclear reactor
China Experimental Fast Reactor
China Experimental Fast Reactor control room
(Photo credits: China Institute of Atomic Energy)
China starts up first fourth generation nuclear reactor
"China starts up first fourth generation nuclear reactor
English.news.cn 2010-07-22 07:22:44
BEIJING, July 21 (Xinhua) --
Chinese scientists have succeeded in testing the country's first experimental fourth generation nuclear reactor, an expert said here on Wednesday.
The successful start up of the China Experimental Fast Reactor (CEFR) marked a breakthrough in China's fourth generation nuclear technology, and made China the eighth country in the world to own the technology, Zhang Donghui, general manager of the CEFR project, told Xinhua over phone.
China's existing 11 nuclear power generating units all use second generation of nuclear power generation technology. The country started the construction of its first third-generation pressurized water reactors using AP1000 technologies developed by U.S.-based Westinghouse in 2009.
Compared with the third generation reactors which have an utility rate of uranium of just one percent, CEFR boasts an utility rate of more than 60 percent.
A new recycling technology called pyroprocessing is also used to close the fuel cycle by separating the unused fuel from most of the radioactive waste.
"The CEFR is safer, more environment-friendly, and more economic than its predecessors," Zhang said."
China Close to Firing Up a Fast Reactor « Carbon-Nation
"
The Chinese Experimental Fast Reactor is so-named because the neutrons produced in its core are not ‘moderated’ with water like those that generate heat in nearly all commercial nuclear reactors. The faster neutrons can burn down nuclear waste and even generate new fuel, promising a solution to the thorny problem of waste storage as well as energy independence.
Fast reactors have proven difficult to operate because most rely on highly flammable liquid sodium to cool the reactor, but their promised benefits keep the hope alive."
China's Fast Breeder Reactor (FBR) Program
"China's Fast Breeder Reactor (FBR) Program
原子能快堆研究中心
China began research on fast neutron breeder reactors in the mid- and late-1960s. During its basic research period from 1965 to 1987, China's research focused on fast reactor technology such as fast reactor physics, thermodynamics, sodium technology and small sodium facility. During this initial period about 12 experimental setups were established, and one sodium loop was constructed. This included a 50 kg 235U zero-power neutron setup. On June 28 June 1970, this device reached criticality. The engineering goal for the applied basic research phase of China's FBR program (1987-1993) was to successfully construct a 65 MWt (25 MWe) experimental fast reactor. Further developments were made in sodium technology, fuel and materials, fast reactor safety, and reactor design. A preliminary foundation for a fast reactor design was established, and approximately 20 experimental setups and sodium loops were built."
Nuclear Engineering International
"Nine years after construction began on the China Experimental Fast Reactor near Beijing, the reactor is close to start up.
First criticality is expected before the end of 2009 and the reactor is due to be connected to the grid in June of 2010.
...
Ordering of components for CEFR began in 1997. The components were imported mainly from Russia, France, USA and UK, with imports from abroad sharing about 30% of the total systems and components budget."
China Experimental Fast Reactor Ready to Connect | Nuclear Energy Insider
"
Following the start of operations for CEFR in June, the next milestone will be the commissioning of the so-called China Demonstration Fast Reactor (CDFR), planned for 2018, though initial work on the design was approved back in 2007.
The CDFR will be located in Fujian province on China’s busy and economically active eastern seaboard, opposite Taiwan.
Following CDFR, the plan is move towards a Chinese developed commercial fast reactor (CCFR), though no preliminary dates have been released for this final stage of the programme as yet – dates including 2028 and 2035 have been [mooted] but not confirmed.
Despite this, the press has reported (unconfirmed by the central government in Beijing but suggested by sources at the government-linked China Institute of Atomic Energy) that several CDFR plants should be in operation by 2030 and that China’s nuclear capacity will rise to 240-250GWe by 2050 with most of this produced by fast breeder reactors that will be introduced to replace China’s current stock of highly polluting, inefficient and costly coal fired power plants.
New record for nuclear, for China
If China does deliver the CEFR in June then it will be the only third power-generating fast reactor in operation globally."
[Note: This is an updated post with new high-resolution pictures from "ANR."]
----------
SANY launches Asia's largest crawler crane
SANY Heavy Industry 1,180-ton crawler crane SCC11800. "SCC11800 crawler crane has a maximum lifting capacity of 1180 tons; the equivalent of lifting six [fully-loaded] Boeing 747 aircraft" (e.g. 88 tons empty weight per Boeing 747).
November 27, 2009 The special-engineering company in Guangdong, with SANY SCC9000-type 900-ton crawler crane, successfully lifts the dome into place at Ningde Nuclear Power Station 1000MW nuclear power plant No. 1.
Sany launches Asia's largest crawler crane.(News roundup) | HighBeam Business: Arrive Prepared
"
Sany launches Asia's largest crawler crane. (News roundup)
Article from: Cranes Today | March 1,
2008
SHANGHAI
SANY SCIENCE & Technology Co, a wholly-owned subsidiary of Sany Group, is launching a crawler crane with a maximum lifting capacity of 900t (and a maximum load-moment of 13,500 tm), which it claims is the largest-capacity crawler ever made by an Asian company.
In the past, large crawler cranes have only been available in China as imports, but
over the last few years Chinese manufacturers have rolled out larger and larger crawlers. Shanghai Sany said its goal is "to fully replace the import of crawler cranes and enter the international market."
In superlift configuration, the crane can lift 900t at 7m radius (and out to 12m), and 800t to 17m. In this …"
SANY America - Heavy Equipment Manufacturing
"About SANY America
SANY Group Company Ltd. was established in 1989 in China.
SANY is the largest heavy equipment manufacturer in China, and also one of the top 10 heavy equipment manufacturers in the world. SANY employs more than 30,000 employees worldwide.
SANY Heavy Industry, a core entity of SANY Group, is a publicly traded company listed on the Shanghai Stock Exchange. SANY Group has had an annual growth rate of 50% for the past 10 years. Despite the impact of global economy recession in 2008 and 2009,
SANY Group maintained a 50% annual growth rate and achieved $3 billion in sales revenue.
As one of the overseas subsidiaries of Sany Heavy Industry Company, Sany America Inc. was founded in 2006. This North American headquarters is located in Peachtree City, Georgia.
September 12, 2007 Sany Heavy Industry signed an investment deal with the State of Georgia. According to this agreement, Sany shall invest in 228 acres and over $100 million to create and establish a state-of-the-art manufacturing facility; constructing and engineering Sany products to be competitive both in price and quality for all of North America. We have broken ground on phase one of our facility and estimate completion in the second half of 2011. The first phase on construction will consist of a 360,000 square foot manufacturing facility as well as 3 stories of office area totaling 180,000 square feet. With an expected 300 employees by the third year,
SANY America will focus on R&D, assembly, marketing and sales of our Truck Mounted Concrete Pumps, Stackers, Handlers, Motor Graders, Drilling Rigs, Excavators and Hydraulic Crawler Cranes which will begin production soon after the completion of our manufacturing facility.
With pride we integrate global resources to provide our customers with excellent equipment and services with unique advantages in cost, performance and localized manufacture, localized management and localized services. At Sany America, we are committed to the North American Market and bringing our customers a successful and outstanding product."
----------
http://www.scienceahead.com/entry/china-gets-success-in-cloning-worlds-first-rabbit/
"
China gets success in cloning world's first rabbit
Parul G | Jul 24 2007
After research of more than three decades in cloning and producing the first cloned animal, a goat in 2000, China has once again been successful in cloning world’s first rabbit. The Chinese scientists have produced the cloned female rabbit biologically, using the somatic cells of a rabbit fetus.
Dr. Li Shangang who conducted the experiment of rabbit cloning is a researcher at the National Center for Molecular Genetics and Animal Breeding of the Beijing Institute of Animal Sciences.
Dr. Li and his team chose the back skin cells of a 20-day old rabbit embryo. They cultured these cells into fibroblast cell lines. Then these fibroblast cells (donor cells) were fused with an enucleated rabbit’s oocyte (immature egg cell of animal ovary) through electric pulse. Thus cloned embroys were produced which were later transferred into the rabbit’s oviduct. The female clone rabbit was born after a month-long normal pregnancy on February 12 and had weighed 60 grams at birth. Now the rabbit is doing well and is at an animal center in Shanghai.
The first animal to be cloned using somatic cells was the sheep - Dolly in 1996. Since then many other animals as mice, cattle and pigs have been cloned by scientists.
In 2002, French scientists too had claimed to produce the world’s first cloned rabbit but that was done by using cells from an adult female rabbit.
However, the Chinese rabbit is the world’s first clone rabbit that has used “fibroblast” cells from a fetal rabbit.
On the achievement, Wang Hongguang, director of the China Center for Biotechnology Development affiliated to the Ministry of Science and Technology said:
Chinese cloning research has reached a global advanced level. We can reproduce almost all the cloning results in top-class laboratories around the world. However, we are lacking in original creations such as the newly cloned rabbit.
Rabbits are considered significant research tools because of their shorter gestation period than other big mammals such as sheep or cows.
Malaysia has also turned to cloning and is in efforts to clone some of its threatened leatherback turtles to save them from extinction.
Source: Reuters"
"China's Liberation Daily reports today that the world's first transgenic-cloned rabbit is now three months old and living happily in Shanghai. The rabbit was cloned from the skin cells of a 20-day-old embryo, which were then implanted into the oviduct of a female rabbit."
(The photo shows the cloned rabbit (left) and her surrogate mother.
Posted by Xujun Eberlein)
http://www.china.org.cn/english/China/236263.htm
"
As rabbits share similar genes with humans, the genetically-modified cloned rabbit is expected to be used for research into cardiovascular and eye diseases as well as some genetic ailments, said Dr. Li Shangang with the Chinese Academy of Agricultural Sciences."
China has been busted many times over. Techniques like what Eltek did may not be sufficient in a court of law, which usually have stricter standards, but they are sufficient for professionals. You think we do not recognize proprietary designs when put a die under a SEM after we cut through the packaging that has a Chinese name on it?
