China Science & Technology Forum

[JSCh]

Single-molecule switch flipped on and off by light
17 June 2016
Tim Wogan

© Science/AAAS​

Researchers have produced a photoswitch comprising just one photosensitive molecule whose electrical conductivity can be turned on and off by light.1 The device may, with further development, have potential in solar energy harvesting and light-sensing applications. It may also be useful in biomedical electronics and optical logic, in which light replaces electrical signals to transmit information.

In the ongoing quest to miniaturise electronics, one ambitious frontier – molecular electronics – involves constructing electronic circuits and devices from individual molecules. Several groups have investigated single-molecule switches. Diarylethenes can exist in either a closed form in which they conduct electricity or an open form in which they are insulators. The free molecule opens when it absorbs a visible photon and closes on absorption of UV. In principle, this allows for a light-sensitive switch.

In 2003, however, researchers at the University of Groningen in the Netherlands who mounted single molecules of diarylethene between gold electrodes found that, even though the switches could be turned off by visible light, they could not then be turned back on by ultraviolet.2 Conversely, researchers using carbon nanotube or graphene electrodes have subsequently reported that the switches become stuck in the 'on' position.3 The problems have been attributed to interactions between the electrodes and the molecules that stabilize one state, preventing the molecule switching.

Using another group’s theoretical analysis, researchers led by Xuefeng Guo of Peking University in Beijing – who carried out the previous work on graphene and nanotube electrodes – calculated that inserting three methylene groups between each graphene electrode and the diarylethene molecule would reduce the interaction between the electronic clouds just enough that, though the molecule would be stable in either configuration, it could still be switched by light. They used a combination of chemical vapour deposition, electron beam lithography and other techniques to fabricate 46 such devices. 'All the devices showed reversible switching properties,' says Guo. They were stable for over a year and could consistently be switched on and off more than 100 times. The researchers are now investigating the switchable quantum effects in detail. 'We're also interested to see whether we can combine several different molecules to do multi-level switching, for example,' says Guo's colleague Hongqi Xu.

'In many cases, molecular junctions have lives of minutes, hours, or in fortunate cases days, but no more,' says Ioan Bâldea of the University of Heidelberg, Germany, who was not involved in the work. 'The fact that here they have switches stable over a year is fantastic! I can't say in which field there will be the strongest impact, but I'm certain there will be an impact.’


Single-molecule switch flipped on and off by light | Chemistry World

Covalently bonded single-molecule junctions with stable and reversible photoswitched conductivity | Science

Stable molecular switches
Many single-molecule current switches have been reported, but most show poor stability because of weak contacts to metal electrodes. Jia et al. covalently bonded a diarylethene molecule to graphene electrodes and achieved stable photoswitching at room temperature (see the Perspective by Frisbie). The incorporation of short bridging alkyl chains between the molecule and graphene decoupled their pielectron systems and allowed fast conversion of the open and closed ring states.

Science, this issue p. 1443; see also p. 1394​

 

[JSCh]

Science stars of China
From ancient DNA to neutrinos and neuroscience, top researchers in China are making big impacts — and raising their country’s standing in science.

20 June 2016

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WU JI: Upward bound | NANCY IP: Making connections | NIENG YAN: Crystal connoisseur | CAIXIA GAO: Crop engineer | CUI WEICHENG: Deep diver | WANG YIFANG: Particle power | QIAOMEI FU: Genome historian | QIN WEIJIA: Polar explorer | CHEN JINING: Pollution patrol | CHAOYANG LU: Quantum wizard



Continue -> Science stars of China : Nature News & Comment

 

[JSCh]

New 'shape-adaptive' device turns body motion into power source (w/ videos)
June 20, 2016 by Bob Yirka

(Tech Xplore)—A combined team of researchers with members from several institutions in China and the Georgia Institute of Technology, has developed a flexible nanogenerator that harnesses the energy from moving body parts and uses it to run electronic devices. In their paper published in the journal Science Advances, the team describes their new device, how they made it bendable, and the ways they believe it might be used.

The first triboelectric nanogenerator (TENG) was developed at Georgian Tech back in 2012, and since that time teams across the world have been hard at work attempting to create consumer devices that will be both useful and inexpensive. If a team succeeds, we might soon seen devices that are affixed to our skin or clothes, powered by nothing more than our movements. Such devices work by using the normal motion of the human body, such as a foot tapping, to cause two different types of material in the device to rub together, or more recently, when they are pressed together, so as to prevent erosion of material. Up till now, most such devices have been rigid. In this new effort, the researchers claim they have developed a flexible TENG that is also stretchable.


Full Story -> New 'shape-adaptive' device turns body motion into power source (w/ videos)

More information: F. Yi et al. A highly shape-adaptive, stretchable design based on conductive liquid for energy harvesting and self-powered biomechanical monitoring, Science Advances (2016). DOI: 10.1126/sciadv.1501624

Abstract
The rapid growth of deformable and stretchable electronics calls for a deformable and stretchable power source. We report a scalable approach for energy harvesters and self-powered sensors that can be highly deformable and stretchable. With conductive liquid contained in a polymer cover, a shape-adaptive triboelectric nanogenerator (saTENG) unit can effectively harvest energy in various working modes. The saTENG can maintain its performance under a strain of as large as 300%. The saTENG is so flexible that it can be conformed to any three-dimensional and curvilinear surface. We demonstrate applications of the saTENG as a wearable power source and self-powered sensor to monitor biomechanical motion. A bracelet-like saTENG worn on the wrist can light up more than 80 light-emitting diodes. Owing to the highly scalable manufacturing process, the saTENG can be easily applied for large-area energy harvesting. In addition, the saTENG can be extended to extract energy from mechanical motion using flowing water as the electrode. This approach provides a new prospect for deformable and stretchable power sources, as well as self-powered sensors, and has potential applications in various areas such as robotics, biomechanics, physiology, kinesiology, and entertainment.​

 

[cirr]

Nature magazine gives nod to 10 star scientists from China

Updated: 2016-06-21 10:23

(Xinhua)

Screenshot of the cover of Nature's feature Science stars of China


LONDON -- Ten of China's leading scientists who have made significant impacts in fields ranging from neuroscience and neutrinos to space science and structural biology were highlighted in Nature magazine's online edition on Monday.

The list includes Wang Yifang, director of the Beijing-based Institute of High Energy Physics, who hopes to build a 50 to 100-km circular particle collider to succeed the 27-km-circumference Large Hadron Collider (LHC) of the CERN (the European Organization for Nuclear Research).

Wang's plan consists of two machines: the first will explore the Higgs particle starting in around 2028, while the next one will occupy the same tunnel and smash particles together with up to seven times the energy of the LHC. This is a bold proposal and will need a huge amount of investment from the government. Wang has proved he could get major projects off the ground and bring in international support, Nature quoted Brian Foster, a physicist at the University of Oxford, as saying.

Also featured were Wu Ji, director-general of China's National Space Science Center, whose basic-space-science missions are putting scientific discovery at the core of China's space program.

The journal listed Lu Chaoyang, deemed a rising star in China's push to master quantum-information technology. Lu is noted for his work with "entanglement," in which the quantum states of different particles are linked regardless of how far apart they are. His goal is to advance quantum entanglement enough to use it for computations.

Four biologists are included in the list: Gao Caixia, whose lab became the first to use the CRISPR-Cas9 gene-editing technique in crops, specifically wheat and rice; structural biologist Yan Nieng who is featured for her work on determining the structures of proteins that are embedded in cells' plasma membranes; Nancy Ip whose leadership and research on basic neural biology and translational research for brain health are bolstering science and biotechnology in China; geneticist Fu Qiaomei whose work could redraft the history of Asia's first anatomically modern humans.

The collection also includes China's Minister of Environmental Protection Chen Jining, who has ramped up the government's efforts to ensure that local officials and companies are following the rules on pollution and industrial development, according to Nature. Qin Weijia, executive deputy director of the Chinese Arctic and Antarctic Administration, is featured for helping to uncover the history of the Antarctic ice sheets.

Cui Weicheng is another featured Chinese scientist. Currently at Shanghai Ocean University, Cui is aiming to reach the deepest place on Earth - the Challenger Deep valley at the bottom of the Mariana Trench, 11,000 meters down. To achieve this goal, he is leading an effort to build a more pressure-resistant, three-person submersible called Rainbow Fish, which is scheduled to be completed in 2020.

"These ten individuals highlight the breadth and promise of innovation in China as the country continues its strong push to become a leader in science," said Richard Monastersky, features editor for Nature.

 

[bobsm]

Chinese scientists lead research to finish totally new human brain mapping
(People's Daily Online) 15:32, June 21, 2016

After six years of efforts, Chinese scientists have finished mapping the human brain in collaborative effort with foreign experts, which is totally new and will provide an indispensable tool for the study of the relationship between the brain and behavior.

Human Brain mapping is the cornerstone of understanding of brain structure and function. The most widely used human brain mapping is Brodmann's map which was made 100 years ago and is based on a single person's body tissue using cytoarchitecture.

Although in recent years, scientists have used magnetic resonance imaging technology to map the human brain, yet the map is divided roughly and difficult to correspond with the function of the brain.

The scientists from the Chinese Academy of Science (CAS) have broken the 100-year-old bottlenecks of traditional mapping of the human brain and have proposed new ideas and methods, including use of brain structure and information regarding function connections to map the human brain. The totally new mapping includes 246 sub-regions, four to five times as detailed as Brodamann’s mapping and it firstly maps the connection of the whole human brain of a living body in a macroscopic manner.

Fan Lingzhong, associate professor of the CAS, said the mapping can provide the connection mode of every sub-region and structure, which will become an indispensable tool for the study of the relationship between the brain and behavior, and for finding new ways to understand the structure and function of the human brain. This has important implications for the design of digital brains inside smart systems.

It will also help to locate areas damaged by strokes and epileptic foci, and in the precise removal of glimoas during neurosurgical operations.


http://en.people.cn/n3/2016/0621/c90000-9075393.html

 

[yusheng]

Polysynthetic twinned TiAl single crystals for high-temperature applications

• Guang Chen1, n1
• Yingbo Peng1, n1
• Gong Zheng1, n1
• Zhixiang Qi1, n1
• Minzhi Wang1,
• Huichen Yu2,
• Chengli Dong2,
• C. T. Liu3,

• Affiliations
• Contributions
• Corresponding authors

Journal name:
Nature Materials
Year published:
(2016)
DOI:
doi:10.1038/nmat4677
Received
09 July 2015
Accepted
24 May 2016
Published online
20 June 2016
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Abstract

• Abstract•
• References•
• Author information•
• Supplementary information

TiAl alloys are lightweight, show decent corrosion resistance and have good mechanical properties at elevated temperatures, making them appealing for high-temperature applications. However, polysynthetic twinned TiAl single crystals fabricated by crystal-seeding methods face substantial challenges, and their service temperatures cannot be raised further. Here we report that Ti–45Al–8Nb single crystals with controlled lamellar orientations can be fabricated by directional solidification without the use of complex seeding methods. Samples with 0° lamellar orientation exhibit an average room temperature tensile ductility of 6.9% and a yield strength of 708 MPa, with a failure strength of 978 MPa due to the formation of extensive nanotwins during plastic deformation. At 900 °C yield strength remains high at 637 MPa, with 8.1% ductility and superior creep resistance. Thus, this TiAl single-crystal alloy could provide expanded opportunities for higher-temperature applications, such as in aeronautics and aerospace.

Subject terms:

• Aerospace engineering•
• Metals and alloys

At a glance
Figures

1. 
   Figure 1: Optical micrographs of directionally solidified Ti–45Al–8Nb PST single crystals at different withdrawal rates.
   a, Longitudinal section of an ingot at a withdrawal rate lower than Vc, showing a PST single crystal with a lamellar orientation aligned parallel to the growth direction. b, Longitudinal section of an ingot at a withdrawal rate higher than Vc, showing a PST single crystal with a lamellar orientation aligned at 45° to the growth direction. c, Magnified lamellar microstructure in the area marked in a, showing more clearly the parallel lamellar microstructure. d, Magnified area marked in b.
   
   
2. 
   Figure 2: Lamellar microstructure of a Ti–45Al–8Nb well-aligned PST single crystal before and after tensile test at ambient temperature.
   a, Bright-field TEM image of a tensile specimen showing the original α2/γ lamellar structure before the test. b, After the tensile deformation, the bright-field TEM image reveals the ultrafine twinning and lamellar structure, with the selected area electron diffraction pattern (inset). c, A high-resolution (HR) TEM image of the deformed specimen showing multiple-twinned structures containing three twin boundaries γA/γB, γB/γC and γC/γD.
   
   
3. 
   Figure 3: Mechanical properties of Ti–45Al–8Nb PST single crystals as a function of temperature and the microstructure after tension.
   a, Mechanical properties as a function of temperature. The well-aligned PST single crystal maintains a high yield strength of 637 MPa at 900 °C; a temperature much higher than the 650–750 °C reported for polycrystalline alloys4 (see the pink-colour region in the figure). b,c, The true stress–strain curve and the work hardening rate obtained at ambient temperature (b) and 900 °C (c). d, TEM microstructure of well-aligned PST single crystals after tension tested at 900 °C. Twins and dislocations appear simultaneously after the elevated-temperature deformation.
   
   
4. 
   Figure 4: Creep properties of well-aligned Ti–45Al–8Nb PST single crystals with the 0° lamellar orientation and the commercial Ti–48Al–2Cr–2Nb polycrystalline alloy at different stresses at 900 °C in air.
   a, Creep strain–lifetime curves. The red lines are for the Ti–45Al–8Nb PST single crystals and the blue lines for the 4822 alloys. The inset is the creep strain–lifetime curves of the 4822 commercial alloy under stresses of 150 and 210 MPa. b, Comparison of the minimum creep rates of the single and polycrystalline materials.
   

http://www.nature.com/nmat/journal/vaop/ncurrent/full/nmat4677.html


中国发动机材料重大突破 寿命优于美国1-2个数量级
新华报业网报道，南京理工大学材料评价与设计教育部工程研究中心陈光教授团队在国家973计划等资助下，经长期研究，在新型航空航天材料钛铝合金方面取得重大跨越性突破。相关成果Polysynthetic twinned TiAl single crystals for high-temperature applications(高温PST钛铝单晶)于2016年6月20日在线发表于Nature Materials(《自然材料》)。 航空航天技术是一个国家科技、工业和国防实力的重要体现。航空发动机被誉为飞机的心脏，叶片则是航空发动机中最关键的核心部件，其承温能力直接决定着发动机的性能，尤其是推重比。

美国GE公司采用Ti-48Al-2Cr-2Nb(以下简称4822)合金替代原来的镍基高温合金制造了GEnx发动机最后两级低压涡轮叶片，使单台发动机减重约200磅，节油20%，氮化物(NOx)排放量减少80%，噪音显著降低，用于波音787飞机，2007年试飞成功，2009年正式投入商业运营，成为当时航空与材料领域轰动性的进展。

陈光教授团队的研究成果在材料性能上实现了新的大幅度跨越，所制备的PST TiAl单晶室温拉伸塑性和屈服强度分别高达6.9%和708MPa，抗拉强度高达978MPa，实现了高强高塑的优异结合。更为重要的是，该合金在900℃时的拉伸屈服强度为637MPa，并具有优异的抗蠕变性能，其最小蠕变速率和持久寿命均优于已经成功应用于GEnx发动机的4822合金1~2个数量级，有望将目前TiAl合金的使用温度从650~750℃提高到900℃以上。

 

[JSCh]

China unveils first embedded neural network processing unit
(People's Daily Online) 14:22, June 22, 2016

​

(Photo: guancha.cn)​

China has launched mass production of the country’s newly-unveiled first ever embedded neural network processing unit (NPU), marking one more major breakthrough in the country’s NPU research and development.

The VC0758 NPU, developed by China’s leading video technology supplier Vimicro is based on a data driven parallel computing model, which can greatly improve the smart chip’s computational ability at a lower power consumption rate, said Zhang Yundong, executive director of the Vimicro State Key Laboratory on digital multimedia chip technology.

Vimicro on Monday announced that it has realized mass production of the VC0758 NPU after five years of research, suggesting that China is now one of the countries with the most advanced artificial intellectual technology in deep learning based on a data driven parallel computing model, according China National Radio (CNR).

Zhang added that the chip is especially skilled in processing multimedia data such as videos and images. Its capabilities will especially be brought into full play when it is used for embedded computer vision applications, CNR reported.

The CNR noted that the smart chip will give a major boost to improvement for China’s video surveillance industry and can help the country to establish a leading position in the world.

According to China Central Television, the VC0758 will be widely employed in drone, intelligent drive assistance systems or in the field of robot vision.

 

[JSCh]

China’s bid to be a DNA superpower
First China conquered DNA sequencing. Now it wants to dominate precision medicine too.

• David Cyranoski
• 22 June 2016

Six years ago, China became the global leader in DNA sequencing — and it was all down to one company, BGI. The Shenzen-based firm had just purchased 128 of the world's fastest sequencing machines and was said to have more than half the world's capacity for decoding DNA. It was assembling an army of upstart young bioinformaticians, collaborating with leading researchers worldwide and publishing the sequences of creatures ranging from ancient humans to the giant panda. The firm was quickly gaining a reputation as a brute-force genome factory — more brawn than brains, said some.


Continue -> China’s bid to be a DNA superpower : Nature News & Comment

Part of Nature's current issue special,

Science in China : Nature News & Comment​

 

[JSCh]

Jiao Tong University - Experimental Observations Reveal the Mystery of Majorana Fermions
June 23, 2016 Author:

About three quarters of a century ago, Ettore Majorana introduced the novel elusive particles into theoretical physics, what are now known as "Marjorana fermions", unlike electrons and positrons, which constitute their own antiparticles. The monumental significance of this development required many intervening decades to fully appreciate, and despite being an "old" idea Majorana fermion remain central to diverse problems across modern physics, not only in neutrino physics, super-symmetry and dark matter, but also on some exotic states of condensed matter.

The observation of Majorana fermions in condensed matter would certainly constitute a landmark achievement from a fundamental physics standpoint, both because it could mean the first realization of Ettore Majoranna's theoretical discovery and, for more importantly, because of the non-Abelian statistics that they harbor. Moreover, success in this search might ultimately prove essential to overcoming one of the grand challenges in the field-the synthesis of a scalable quantum computer.

In 2008, Fu and Kane provided a groundbreaking development by theoretically predicting that Majorana bound states can appear at the interface between topological insulators (TIs) and superconductors. Topological superconductors (TSCs) become a research focus soon after they were theoretically expected to host Majorana fermions. So far, however, no TSC materials have been found in nature although there are some possible candidates. The theoretical work proposed that a topological insulator surface should show topological superconductivity when it is covered by a normal superconductor, i.e., a SC/TI heterostructure. In practice, however, it is difficult to grow a SC on a TI surface due to the poor thermo-stability of the TI materials and the chemical reaction at the interface. In 2012, Prof. Jinfeng Jia's group of Shanghai Jiao Tong University published a paper in Science (Science 336, 52-55 (2012)) which reported the first successful fabrication of a TI/SC heterostructure instead of the SC/TI heterosctructure. The coexistence of superconductivity and topological surface states was realized on the surface of the Bi2Se3/NbSe2 heterosctructure for the first time.

In 2014, Prof. Jinfeng Jia's group continued their intense search to provide experimental evidence of topological superconductivity in their special heterostructure, and published a paper in Physical Review Letters (Vol. 112, Page 217001) with their coworkers.In this work, a topological insulator/superconductor (TI/SC) heterosctructure, Bi2Te3/NbSe2, was investigated by using ultra-low-temperature and high-magnetic-field scanning tunneling spectroscope, resulting in a series of research achievement. It is the first time in experiments that the TI/SC heterostructure was demonstrated to be an artificial TSC. It is also the first time that quantum magnetic vortices and Andreev bound states were directly observed on a proximity-effect induced TSC, which lays the foundation for the search of Majorana fermions in condensed matter physics.

In 2015, the signatures of Majorana fermions were observed by systematically investigating the spatial profile of the Majorana mode and the bound quasiparticle states within a vortex in Bi2Te3/NbSe2. While the zero bias peak in local conductance splits right off the vortex center in conventional superconductors, it splits off at a finite distance ∼20 nm away from the vortex center in Bi2Te3. This unusual splitting behavior suggested its origin of the Majorana fermion zero mode. This work provides self-consistent evidences of Majorana fermions and was published in PRL, the coauthors include Prof. Fuchun Zhang and ZhuAn Xu of Zhejiang University, Q.H Wang of Nanjing University, Y. Liu of Pennsylvania State University and Q.K. Xue of Tsinghua University.

Most recently, on the basis of the above work, Professor Jia's research group made an important and historic step forward in searching Majorana fermions in the TI/SC heterostructures, together with other people in Collaborative Innovation Center of Advanced Micro-structure, including ZhuAn Xu’s group in Zhejiang University, Shaochun Li's group in Nanjing University; and Liang Fu at MIT. They announced that they have firstly observed the tracks of the mysterious majoronna particle in the vortex. The vortex center in a topological insulator / superconductor heterojunction surface is carefully measured by spin polarized scanning tunneling microscopy/spectroscopy. The specific spin polarized current which caused by the Marjorana particle has been clearly observed. The experimental data are strongly supported by the theoretical calculations. This work gives a definite evidence for the existence of Majorana fermions. For the first time, spin properties of Majorana particles are observed. They also provide an effective way to control the existence of Majorana particles by means of interaction. They lifted the veil of mysterious Majorana fermions, generate the possibility for the further research and application of the Majorana fermions. Their research work has been published in PRL online. As commented by a referee of the PRL, the experiment results are clear and convincing. They also provide a direct approach for observing the mysterious Majorana fermions.

Reviewed by: Liu Yiting

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Majorana Zero Mode Detected with Spin Selective Andreev Reflection in the Vortex of a Topological Superconductor, Phys. Rev. Lett. (2016). DOI:10.1103/PhysRevLett.116.257003
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Chinese scientists find the existence of the Majorana fermion particle
CCTV News

Published on Jun 22, 2016
A major discovery in theoretical physics has been revealed in Shanghai’s Jiaotong University. Evidence has surfaced that proves beyond reasonable doubt the existence of the particle, Majorana fermions. CCTV’s Shi Wenjing has more.

 

[JSCh]

Bird wings trapped in amber are a fossil first from the age of dinosaurs
Preserved feathers and tissue provide a picture of hatchlings from the Cretaceous.

• Rachel Becker
• 28 June 2016

Two tiny wings locked in amber 99 million years ago suggest that in the middle of the Cretaceous period — when dinosaurs still walked the planet — bird feathers already looked a lot like they do today.

A team of researchers led by Lida Xing, a palaeontologist at the China University of Geosciences in Beijing, recovered a first for the time period: a few cubic centimetres of amber from northeastern Myanmar that contained the partial remains of two bird wings. The specimens include bone, feathers and skin, according to a study published on 28 June in Nature Communications

Full Story -> Bird wings trapped in amber are a fossil first from the age of dinosaurs : Nature News & Comment

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Mummified precocial bird wings in mid-Cretaceous Burmese amber : Nature Communications : Nature Publishing Group

 

[JSCh]

Household fuels exceed power plants, cars as smog source in Beijing – Princeton Engineering

Posted Jun 27, 2016
By John Sullivan

Beijing and surrounding areas of China often suffer from choking smog. The Chinese government has made commitments to improve air quality and has achieved notable results in reducing emissions from the power and transportation sectors. However, new research indicates that the government could dramatically improve air quality with more attention to an overlooked source of outdoor pollution — residential cooking and heating.

"Coal and other dirty solid fuels are frequently used in homes for cooking and heating," said Denise Mauzerall, a researcher who led the study and professor of civil and environmental engineering and public and international affairs at Princeton University. "Because these emissions are essentially uncontrolled they emit a disproportionately large amount of air pollutants which contribute substantially to smog in Beijing and surrounding regions."

Households account for about 18 percent of total energy use in the Beijing region but produce 50 percent of black carbon emissions and 69 percent of organic carbon emissions, according to a research team from institutions including Princeton, the University of California Berkeley, Peking University and Tsinghua University. In the Beijing area, households contribute more pollutants in the form of small soot particles (which are particularly hazardous to human health) than the transportation sector and power plants combined; in the winter heating season, households also contribute more small particles than do industrial sources.

The researchers said the high levels of air pollutant emissions are due to the use of coal and other dirty fuels in small stoves and heaters that lack the pollution controls in place in power plants, vehicles and at some factories.

The "use of solid fuels (coal and biomass) for heating and cooking in households contributes directly to exposures in and around residences and is a major source of ill health in China," the researchers wrote in an article published online June 27 in the Proceedings of the National Academy of Sciences. The researchers said illness caused by air pollution was a leading cause of premature death in China, ranking between high blood pressure and smoking as risk factors.

The researchers used a sophisticated air pollution model to evaluate the benefits of reducing residential emissions on air pollution levels in Beijing and the surrounding region in the winter of 2010. The region in the study, which has a population of 104 million people, and frequently has air pollution levels more than six times higher than what the World Health Organization considers a safe limit, included Beijing and the surrounding Tianjin and Hebei provinces. The researchers ran computer model simulations in which they removed a varying amount of residential emissions in Beijing alone as well as the entire Beijing-Tianjin-Hebei (BTH) region and found that reducing residential emissions resulted in corresponding drops in outdoor pollution levels.

"The residential sector has been relatively overlooked in ambient air pollution control strategies," Mauzerall said. "Our analysis indicates that air quality in the Beijing region would substantially benefit from reducing residential sector emissions from within Beijing and from surrounding provinces. Air pollution levels in Beijing would greatly benefit from a regional strategy to reduce emissions from dirty cook stoves."

The researchers concluded from their study that eliminating household emissions alone would reduce levels of small particulate pollution in the air over Beijing in winter by about 22 percent, but that eliminating household emissions in all three provinces that include Beijing would nearly double the reduction in particulate levels in the city itself.

"Reducing residential emissions from the entire region, including the surrounding rural areas, has the potential to greatly improve air quality within Beijing and its suburbs," Mauzerall said.

The researchers said the government can take additional steps both in the near term and the future to reduce emissions. Natural gas, liquid petroleum gas, cleaner solid-fuel stoves and electricity can presently reduce emissions. In the long-term electricity from renewable energy sources would virtually eliminate the emissions of air pollutants and the greenhouse gases that contribute to climate change.

Besides Mauzerall, the paper's authors include: Jun Liu, Qi Chen, Yu Song, Xinghua Qiu, and Shiqiu Zhang of the College of Environmental Sciences and Engineering, Peking University; Qiang Zhang of Tsinghua University; Wei Peng of the Woodrow Wilson School of Public and International Affairs, Princeton University; Zbigniew Klimont of the Institute for Applied Systems Analysis; Weili Lin of the Chinese Academy of Meteorological Sciences; Kirk Smith, the school of public health, University of California, Berkeley.

The work appeared in the Proceedings of the National Academy of Science and was supported in part by the National Natural Science Foundation Committee of China, the European Seventh Framework Programme Project PURGE, the Collaborative Innovation Center for Regional Environmental Quality, and the Council for International Teaching and Research at Princeton.

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Liu J, Mauzerall DL, Chen Q, Zhang Q, Song Y, Peng W, Klimont Z, Qiu X, Zhang S, Hu M, Smith KR, Zhu T, 2016, Air pollutant emissions from Chinese households: A major and underappreciated ambient pollution source, Proc Nat Acad of Sci, www.pnas.org/cgi/doi/ 10.1073/pnas.1604537113 (in press)

 

[JSCh]

Cold spring discovered in S. China Sea
People's Daily Online, June 28, 2016

The unmanned remotely operated vehicle "Haima". [Photo / Guangzhou Daily]​

China has unveiled its latest discovery of a cold spring in the South China Sea, gesturing a major step forward in flammable ice exploitation in the region.

The cold spring, coded as Haima or sea horse, is located in the southern waters of the Pearl River basin. Covering an area of 618 square kilometers, it is about 1,350 to 1,430 meters' deep and various kinds of cold spring activities could be detected throughout 350 square kilometers of the total area, according to the preliminary discovery results made public on Saturday in Guangzhou City of southern China’s Guangdong Province, the Guangzhou Daily reported.

The China Geology Survey (CGS) under the Ministry of Land and Resources said it began to detect cold springs on the northern continental slope of the South China Sea in 1999. The Haima cold spring was detected in March 2015 by the unmanned remotely operated vehicle "Haima" during its first mission conducting an oceanic geological survey.

According to the CGS, the Haima cold spring is full of natural gas hydrates on the shallow strata. There are also many authigenic carbonates exposed on its surface due to large quantities of methane gas leakage. Different kinds of organism groups co-exist in the cold spring, especially sea mussels which grow on the carbonates.

Methane gas could be detected at the cold springs, which suggests possible storage of natural gas hydrates, including flammable ice, the Guangzhou Daily reported.

The Haima cold spring discovery has proved the rich storage of natural gas hydrates within China's territorial waters, the newspaper noted, adding that an engineering technological center has been launched in Guangzhou, aiming to further promote China’s detection and exploitation abilities of natural gas hydrates in China's sea area.

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Researchers Find Effects of Ensembles on Methane Hydrate Nucleation Kinetics
Jun 28, 2016

Methane hydrate is a crystalline compound made from space-filling cages of water molecules that accommodate methane. It exists in much of the sediments that cover the oceanic floor as well as in permafrost. Research on methane hydrate nucleation kinetics is important for hydrate recovery and storage, developing kinetic hydrate inhibitors, and designing oil-gas transportation pipelines.

Post-doctor ZHANG Zhengcai, and his supervisor Prof. GUO Guangjun, Institute of Geology and Geophysics, Chinese Academy of Sciences(IGGCAS), together with their co-workers, have undertake molecular dynamics simulations to investigate the nucleation kinetics of methane hydrate.

Continue -> Researchers Find Effects of Ensembles on Methane Hydrate Nucleation Kinetics | Chinese Academy of Sciences

 

[JSCh]

640,000-year-old cave stalagmites in China help scientists understand how last seven ice ages ended
Dating stalagmites and measuring oxygen isotope levels allows researchers a clearer picture of past climate.

• By Léa Surugue
• June 29, 2016 18:00 BST

A detailed analysis of stalagmites in the Chinese cave of Sanbao has revealed that cyclical changes in the level of solar radiation reaching the Earth may have contributed to the end of the seven most recent ice ages. The stalagmites also provided the most detailed and accurate record to date of variations in the Asian Monsoon.

Scientists generally use uranium/thorium dating to determine the age of calcium carbonate materials such as stalagmites. In this study published in Nature, the researchers used this method to date the stalagmites in the cave. They managed to date them back to 640,000 years ago – pushing back the limits of how far it is possible to go back in time with uranium/thorium dating.

The researchers also measured oxygen isotope levels to determine past characteristics of the climate, such as temperature and monsoon strength.

Combined with the uranium/thorium dating, this stalagmite data enabled them to precisely date when different climatic events occurred over hundreds of thousands of years, and to investigate whether cyclical changes in the level of solar radiation had anything to do with it.

Monsoon strength and ice age
The scientists used four stalagmites that they collected 1.5km (just under a mile) from the cave mouth, and dated their formation with the uranium/thorium dating technique. They also used the stalagmites to construct a record of composite oxygen levels starting from 640,000 years ago.

Over this long period of time, the gradual shift in the orientation of Earth's axis of rotation – a process known as precession – caused changes in solar radiation. This new record suggests that precession led to the end of ice ages as well as the reduction of rainfall during Monsoon season recorded by the stalagmites.

"Insolation changes caused by the Earth's precession drove the terminations of each of the last seven ice ages as well as the millennia-long intervals of reduced monsoon rainfall associated with each of the terminations", the scientists have said.

Another interesting finding is that oxygen isotope record they have come up with also indicates that the end of each ice age were separated by four or five precession cycles, each lasting around 20,000. This supports the commonly accepted idea that ice age cycles are separated by 100,000 years.

http://www.ibtimes.co.uk/stalagmites-china-tell-story-asian-monsoon-end-ice-ages-1568114

 

[JSCh]

China expanding capacity of dark matter detector
(Xinhua) 08:52, June 30, 2016

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XICHANG, June 29, 2016 (Xinhua) -- An experimenter of Dark Matter Experiment "PandaX", which means Particle and Astrophysical Xenon Detector, checks facilities in the Jinping Underground Laboratory, located at 2,400 meters under the surface of Jinping Hydropower Station, in southwest China's Sichuan Province, June 28, 2016. PandaX is designed to build and operate a ton-scale liquid xenon experiment to detect the dark matter, invisible material that scientists say makes up most of the universe's mass. The PandaX program, headed by China's Shanghai Jiao Tong University, was conducted in the Jinping lab, one of the world's deepest underground labs opened in December 2010. The Jinping lab provides a "clean" space for scientists to pursue the dark matter. Researchers said the extreme depth helps block most cosmic rays that mess with the observation. (Xinhua/Xue Yubin)​

CHENGDU, June 29 (Xinhua) -- Chinese scientists are expanding the capacity of an underground facility designed to detect elusive dark matter particles.

Scientists are still searching for evidence to prove the existence of the hypothetical dark matter, an invisible substance thought to account for over a quarter of the universe's mass-energy balance.

The Jinping Underground Laboratory, which is 2,400 meters under a mountain in Sichuan Province, started operating in December 2010. It has a store of xenon, one of the few materials that interact with dark matter, and the cosmic rays that commonly interfere with attempts to observe dark matter generally cannot penetrate to such a depth underground.

Xiao Mengjiao, a researcher at the laboratory, said he and his colleagues have started the second phase of their experiment.

The lab now stores 300 kilograms of xenon, an expansion from the54 kilograms in the first phase.

"In the future, the quantity of xenon will reach a number of tons, but it will depend on when the research funding arrives," Xiao said.

The second phase, which will last about a year, "will take us further on our way to find dark matter signals," he added.

Analysis of data collected during a trial run of the second phase from November to December is complete, according to the scientist. "The results are a significant step forward from the first phase, because we are able to focus on areas where dark matter is most likely to be observed," he said.

"We have reason to believe we are on the verge of finding dark matter."

But the researchers may need to keep up their current pace if China is to win the race in this field.

"International competition in the hunt for dark matter has gotten quite fierce, and many are building larger detection equipment and adopting more cutting-edge technology," Xiao said.

According to Liu Jiang, another lab researcher, "Dark matter is like the smog in the universe and the Earth is like a car that rides through the smog. It is the detectors' responsibility to record the 'sound' of collision between the car and the smog."

 

[ahojunk]

One of the scientist looks like a foreigner. This is good as it shows collaboration with other scientists.