What's new

China Science & Technology Forum

China Nuclear to bring nuclear power to Saudi Arabia
By Lyu Chang and Hu Meidong in Fuzhou (China Daily) Updated: 2016-01-21 07:28

f8bc126d980d180a580301.jpg

Nuclear reactors under construction in Sanmen, Zhejiang province.[Photo/Xinhua]

China Nuclear Engineering Group Corp signed an agreement with Saudi Arabia on Tuesday to develop its homegrown fourth-generation nuclear technology in the oil-rich Middle East country.

Gu Jun, president and general manager of CNEC, said the agreement was a major step toward the export of high-temperature gas-cooled reactors, an indigenous nuclear technology jointly developed by CNEC and Tsinghua University.

He made the remarks during a ceremony in Beijing held by the Fuzhou New Economic Area, in which the Chinese company plans to invest nearly 16.3 billion yuan ($2.48 billion) to build a nuclear manufacturing equipment industrial cluster and a production base for nuclear graphite, a key material used in high-temperature gas-cooled reactors.

"The timing is right for the export of such a type of nuclear reactor," CNEC said in a statement.

About 95 percent of the high-temperature reactor, which uses a graphite-moderated core with a uranium fuel cycle to generate heat with less radioactive effect and higher efficiency, can be manufactured domestically, apart from the nuclear graphite, which relies largely on imports.

Experts said despite Saudi Arabia being a fossil-fuel rich country, the country still needs to meet demand from growing energy consumption.

"Nuclear power plants with a design life of more than 40 years cannot only provide energy security but also have the potential to resolve growing emissions concerns in the Middle East," said Lin Boqiang, director of the China Center for Energy Economics Research at Xiamen University.

Saudi Arabia hopes to build 16 reactors by 2032 to meet its growing energy demand, involving a total investment of more than $80 billion. Its first reactor is likely to go on line in 2022, earlier reports said.

CNEC said it is also targeting other foreign markets including South Africa and the United Arab Emirates.

It said that the agreement with Saudi Arabia will bring other possibilities for nuclear cooperation between China and other partners along the Belt and Road Initiative, which includes more than 60 economies along the Silk Road Economic Belt and the 21st Century Maritime Silk Road.
 
.
Localized oxidative killing of tumor cells by glassy iron nanoparticles
January 20, 2016

Amorphous iron nanoparticles have a specific toxicity in tumor cells. In the journal Angewandte Chemie, Chinese scientists describe their design and synthesis of a special amorphous state of nanoparticulate iron, which can locally release reactive iron species in the acidic and hydrogen peroxide rich environment of cancer cells, providing new possibilities for theranostics and chemodynamic therapies.

Read more at: Localized oxidative killing of tumor cells by glassy iron nanoparticles

More information: Chen Zhang et al. Synthesis of Iron Nanometallic Glasses and Their Application in Cancer Therapy by a Localized Fenton Reaction, Angewandte Chemie International Edition (2016). DOI: 10.1002/anie.201510031
 
.
20 January 2016
Glass-based Ultraviolet Absorbers Act as ‘Biological Shields’
A special metal oxide glass created by researchers in China can help protect living cells by absorbing and blocking damaging ultraviolet rays

WASHINGTON – If you’ve ever experienced a bad sunburn, you know the damage that ultraviolet (UV) light can cause to living cells (like your skin). Out in space, where the level of radiation from the sun can be even higher, it can damage sensitive electronics aboard in-flight spacecraft.

The dangers of UV light have prompted scientists to search for versatile materials that block UV and can withstand long radiation exposure times without falling apart. Now a group of researchers in China has developed a new method to create transparent, glass-based materials with UV–absorbing power and long lifetimes. The team demonstrated that the new glass effectively protects living cells and organic dyes, and believe it could also be developed as a transparent shield to protect electronics in space. They describe their results in Optical Materials Express, a journal of The Optical Society.

The researchers used a metal oxide —cerium (IV) oxide (CeO2)— well-known for its ability to absorb UV photons to craft the composite glass-based UV absorber.

Other key features of the final composite material are the optical transparency of the glass and the material’s ability to suppress the separation of photo-generated electrons and holes. The later feature slows down a light-induced reaction that would lead to the ultimate breakdown of the material under prolonged exposure to UV radiation.

The method the team developed is based on the self-limited nanocrystallization of glass.

“Self-limited nanocrystallization of glass can be achieved by taking advantage of the rigid environment of the solid-state matrix, rather than the conventional solution and vapor conditions to modulate the ionic migration kinetics,” explained Shifeng Zhou, School of Materials Science and Engineering, South China University of Technology, Guangzhou, China. “It allows us to create glass-ceramics embedded with a CeO2:fluorine (F) nanostructure.”

The viscous glass matrix involved poses a considerable constraint for oxide (O2-) and F- ion diffusion, so the group gradually etches trifluorocerium (CeF3) by O2- ions within an oxide matrix until F--doped CeO2 is generated in a controllable manner. It’s important to note that this technology is also routinely used to prepare other UV absorbers such as zinc oxide (ZnO) and titanium oxide (TiO2).

“This work establishes an effective approach for the functionalization of glass,” said Zhou. “And it allowed us to demonstrate the construction of a novel glass-based UV absorber.”

The group’s innovative approach for fabricating the UV absorber has important implications “for the construction of novel glass materials with new functions via microstructure engineering,” he added.

Among the group’s key discoveries was finding that the self-limited nanocrystallization of glass is indeed an effective way to functionalize it. The special glass they created suppresses photocatalytic and catalytic activity, while boasting an extremely high UV-absorbing capacity.

“Our glass shows excellent optical quality, and it can be easily fabricated either in bulk form or as a film,” said Zhou. “It effectively protects organic dye and living cells from UV radiation damage.”

Potential applications for the group’s work include radiation hardening of electronic devices, serving as a biological shield, and preserving cultural artifacts and relics.

“In space, the high-energy radiation environment encountered by electronic equipment aboard spacecraft can be quite damaging,” noted Zhou. “Fortunately, in the future, if you add a radiation-blocking coating onto the surface of the package – a transparent glass/polymer material – the device would be well protected, and its service lifetime may be prolonged.”

In terms of applications as biological shields and to preserve cultural artifacts and relics, the special glass can “protect cells from UV-induced damage,” he added.

Going forward, the group plans to focus their efforts on developing other novel and effective glass-based UV absorbers, using the self-limited nanocrystallization method.

“We’ll explore ways for large-scale fabrication of this type of film, which is extremely important for practical applications,” said Zhou. “Our group will also further study the functionalization of glass based on its microstructure engineering, because we believe this fundamental research may have great significance for the glass industry.”

Paper: B. Zheng, Z. Wang, Q. Guo, S. Zhou. "Glass Composite as Robust UV Absorber for Biological Protection,” Optical Materials Express 6, 531-539 (2016)

Glass-based Ultraviolet Absorbers Act as ‘Biological Shields’ | News Releases | The Optical Society
 
.
Intel Xeon chips to get a Chinese sidekick

By Pete Carey / January 21, 2016 at 10:53 AM

browse.php


Intel unveiled a “strategic collaboration” Thursday with a Chinese university to make a computer processor module that would run alongside the Xeon processors that power Chinese data centers.

Intel is providing more than $100 million to support the project.

The Santa Clara chip giant said the module would “add capabilities that address specific local requirements” and help protect the intellectual property of both Intel and China.

The new module — containing a processor and system software — will be developed by Intel and Tsinghua University and commercialized by Montage Technology Global Holdings. It will be based on “reconfigurable” technology developed by Tsinghua University, which is spearheading China’s drive to develop a home-grown chip industry.

“Intel wants to expand its market presence in China, especially in the large data center,” said industry analyst Jack Gold of J. Gold Associates. “The way to do that is to partner with local users who are going to drive the market. It’s like Intel partnering with MIT or Stanford.” The arrangement allows Intel to protect its processes while Tsinghua will keep what it designs, he said.

The Chinese government has also been concerned about protecting its technology following revelations of eavesdropping by the National Security Agency.

“China wants their own CPU for government-funded organizations,” said industry analyst Patrick Moorhead of Moor Insights and Strategy. “It’s part of what is called China 2016 with the desire to own the security. In this scenario, Intel provided the Xeon and then Montage adds the security bits, packages it, and ships it” to Chinese manufacturers.”

Raj Hazra, Intel data center group vice president, explained in the announcement that the Chinese data center market is growing rapidly and diversifying, and the chip would address various “local requirements.”

He said Intel collaborates with companies that use Xeon chips but add on their own innovations.

“We believe this new collaboration is a win-win as it enables TU and Montage to innovate alongside standard Intel Xeon processors to create new and compelling indigenous products while preserving the respective intellectual property of all parties,” Hazra said in a blog post.

Montage Technology Group specializes in chips for home entertainment and the data center cloud. It was acquired by Montage Technology Global Holdings in 2014, an investment group that was formed by Shanghai Pudong Science and Technology Investment and China Electronics Investment Holdings, which is a subsidiary of CEC, the largest state-owned IT company in China.

Intel said it has invested more than $7.5 billion in China in the past 30 years, including recent collaborations with Rockchip and Spreadtrum Communications targeting mobility.

Intel Xeon chips to get a Chinese sidekick
 
.
Intel Links Up With China in Server-Chip Venture

The alliance comes as China looks to step up local production of tech components amid cybersecurity concerns


browse.php

Intel, which has operated in China for three decades, is in a server-chip venture with two Chinese entities. PHOTO: ASSOCIATED PRESS

By DON CLARK and EVA DOU

Jan. 21, 2016 1:06 a.m. ET

Intel Corp. has formed an unusual chip venture with two partners in China that could help address concerns about the security of imported technology.

The arrangement with Tsinghua University and Montage Technology Global Holdings Ltd., aided by more than $100 million in research funding from Intel, follows calls by Chinese officials to reduce the country’s reliance on foreign-made semiconductors—particularly those used in systems that could be targeted by spies from abroad.

Intel said the university, known as TU, will develop a programmable chip that would be placed in a plastic module alongside one of its Xeon microprocessors, the most widely used calculating engine in corporate and government data centers. The additional chip—called a reconfigurable computing processor, or RCP—and associated software developed by the university would add capabilities that address “specific local requirements.”

The company declined to discuss what those requirements may be. ButMartin Reynolds, a Gartner Inc. analyst briefed on the ventures, said a likely possibility is that the RCP would help ensure that the Intel chip doesn’t carry out suspicious activity.

“It lets you kind of prove the Xeon is behaving as it is supposed to be,” Mr. Reynolds said.

Intel in 2014 announced a deal to invest $1.5 billion for a 20% stake in a holding company owned by Tsinghua Unigroup Ltd., which is owned by the university. That holding company owns two Chinese chip designers.

Montage, a subsidiary of one of China’s largest state-owned tech companies, CEC, which makes electronics for the government and military, will commercialize the modules containing the two chips, starting in 2017.

“We believe this new collaboration is a win-win as it enables TU and Montage to innovate alongside standard Intel Xeon processors to create new and compelling indigenous products while preserving the respective intellectual-property ownership of all parties,” said Raj Hazra, a vice president in Intel’s data-center group, in a blog post.

The venture was announced in a ceremony in Beijing.

Intel has operated in China for three decades. The company has one chip-fabrication facility, which Intel said in October it would adapt to begin making memory chips at a cost of up to $5.5 billion.

The Santa Clara, Calif., company’s latest announcement comes amid widening concerns about the health of the Chinese economy. Intel echoed such concerns in a forecast issued last week for the 2016 first quarter that caused a sharp drop in its stock price.

But most analysts believe any slowdown in China’s technology purchase is most likely to affect personal computers. They don’t see a slowdown in local purchases to expand the capacity of the country’s data centers.

Indeed, the company’s announcement follows a server-chip venture announced Sunday by Qualcomm Inc., a dominant maker of chips for mobile phones that is taking steps to diversify its business. That venture, which will be 55% owned by the province of Guizhou and 45% by Qualcomm, will rely on the technology licensed by ARM Holdings PLC that is a mainstay in smartphones. But Qualcomm officials said the venture may make chips with modifications for the local market.

Intel Links Up With China in Server-Chip Venture - WSJ
 
.
China planning new supercomputer
Source: Xinhua 2016-01-22 19:26:01

TIANJIN, Jan. 22 (Xinhua) -- China is planning a supercomputer 1,000 times more powerful than its groundbreaking Tianhe-1A as it faces rising demand for next-generation computing.

Meng Xiangfei, head of the applications department of the National Supercomputer Center, said on Friday that the center will release a prototype in 2017 or 2018 of an "exascale" computer -- one capable of at least a billion billion calculations per second

Exascale computing is considered the next frontier in the development of supercomputers.

Tianhe-1A was recognized as the world's fastest computing system in 2010. Though it has since been superseded by Tianhe-2, Tianhe-1A is being more widely used. Computer scientists are finding it challenging to run contemporary applications at their optimum on faster supercomputers.

With its uses including oil exploration data management, animation and video effects, biomedical data processing and high-end equipment manufacturing, Tianhe-1A's capacity is being stretched, said Meng.

It is carrying out more than 1,400 computing tasks and serving about 1,000 users per day.

The exascale computer will be wholly independently developed by the National Supercomputer Center, according to Meng.

About a seventh of Tianhe-1A's CPU chips are Chinese.


China planning new supercomputer
- Xinhua | English.news.cn
 
.
GAOFEN 4, THE WORLD’S MOST POWERFUL GEO SPY SATELLITE, CONTINUES CHINA’S GREAT LEAP FORWARD INTO SPACE
January 8, 2016

Blog, Discovery, Images, Latest News, Science, Technology, Trends
FacebookTwitterSubscribe


On December 28, 2015, a Long March 3B/G2 rocket launched from Xichang and lofted into space the 4.6 ton Gaofen-4 imaging satellite.

Billed as a disaster relief satellite, the Gaofen 4 was placed in Geosynchronous Orbit (GEO). GEO satellites constantly stay above a patch of Earth, thus providing constant 24 hour surveillance of a geographic area. By contrast, low earth orbit (LEO) satellites such as the U.S. KH-11 spy satellites are closer to the Earth, so their speed exceeds that of the Earth’s rotation (meaning that they cannot maintain continuous surveillance over specific locations). In the Gaofen 4’s case, its range of view is a 7,000km by 7,000km box of 49 million square kilometers of Asian land and water in and around China.

The Gaofen 4 is the world’s most powerful GEO spy satellite. It has a color image resolution of slightly less than 50 meters (which is enough to track aircraft carriers by their wake at sea) and a thermal imaging resolution of 400m (good for spotting forest fires). It may also have a lower resolution video streaming capacity. Because of its round-the-clock coverage of Chinese territory and near aboard, Gaofen 4 can provide instant coverage of earthquake or typhoon hit areas to support humanitarian relief. It will also allow China to monitor strategic foreign sites such as WMD facilities and naval bases inside its observation box.

jilin_satellite.jpg

Jilin Constellation
When the Jilin satellite constellation is completed in 2030, it will have 138 small satellites that provide a snapshot of any place on Earth every ten minutes. | Jilin Provincial Government


The satellite is part of the dual use China High-Resolution Earth Observation System (CHEOS), which already has five other satellites (Gaofen 1, 2, 3, 5 and 8). This fits within a larger program of radar, imaging, hyperspectral and atmosphere monitoring satellites that will support Chinese civilian missions like agriculture, construction, disaster relief and climate change monitoring. Of course, the Chinese Aerospace Force (a new branch of the PLA following its December 2015 reorganization) could easily make use of such satellites during Chinese military operations. Also of interest is the Jilin LEO imaging satellites (sponsored by the Jilin Provincial government); the first four Jilin satellites launched in October 2015 and already have 80cm imaging resolution. By 2030, the Jilin constellation will have 138 imaging, high-resolution small satellites that provide all weather coverage of any point on Earth, at 10 minute intervals.

With a lifespan of 8 years, the Gaofen 4 will likely be superseded by future GEO observation satellites with higher resolution imaging capabilities. One intriguing possibility is revealed in a study from a Chinese engineering journal. Enterprising scientists propose that a future GEO spy satellite could deploy a foldable telescope lens of over 20 meters diameter, which could be powerful enough provide sub 1-meter resolution (similar to Ball Aerospace and DARPA’s Membrane Optics program). Such a futuristic GEO spy satellite wouldn’t just be able to find interesting targets like aircraft carriers and missile launcher trucks, it could beam back real time video streams of enemy forces underway.

http://astronaut.com/gaofen-4-the-w...ntinues-chinas-great-leap-forward-into-space/

.
 
.
Genetic research on monkeys offers hope for autism sufferers
By Cai Wenjun | January 26, 2016, Tuesday

MONKEYS could lead the way in the pursuit of a cure for autism.

Pioneering local scientists have for the first time successfully implanted a human autism gene into a monkey and produced two generations of animals that exhibit symptoms of the neurodevelopment disorder.

The “transgenic” macaques behaved similarly to humans afflicted with autism, the team from the Chinese Academy of Sciences’ Institute of Neuroscience wrote — making repetitive gestures, and displaying anxiety and poor social interaction.

This meant they could serve as a reliable animal model for researching the causes of, and possible cures for, autism in humans.

Previous research on autism has been focused on mice, whose brains are much smaller and less complex than those of humans, and are therefore unable to exhibit significant autism-like symptoms.

Autistic people usually have trouble interacting socially and struggle with anxiety and emotional problems.

Among children aged 6 and under, 78 percent of those who are treated for psychiatric problems are autistic.

There is so far no cure for autism, and its exact effects on the brain remain unclear.

“Autism is a highly genetic disorder and it is related to over 100 genes. So the treatment of autism and the establishment of an autism animal model are critical goals in both medicine and neuroscience,” said Qiu Zilong, who led the study.

“Among the responsible genes, we chose MECP2, as all people with duplicated MECP2 are found to have autism. It is an important gene for autism.”

Qiu’s team began its research in 2009, producing the first generation of transgenic monkeys to manifest human MECP2 duplication in 2011.

The monkeys were borne by surrogate females, and their behavior studied as they grew up.

The researchers observed “an increased frequency of repetitive circular locomotion, increased anxiety, reduced social interaction,” among other behaviors.

The second generation of these monkeys, who were born in 2014, also exhibited autism-like behaviors, demonstrating a genetic heritage of MECP2.

“This work demonstrated the feasibility and reliability of using genetically engineered non-human primates to study brain disorders,” Qiu said. “We have started further research on these monkeys, which are receiving brain-imaging tests to study which parts of the brain and which neural circuits experience abnormal functions.

“Once we identify this brain circuit [problem] associated with the autism-like behavior, we will use therapeutics such as gene-editing tools to manipulate this MECP2 transgene in the transgenic monkey,” he explained.

“With such information, scientists can develop more medicines and gene therapies for autism treatment.”

http://www.shanghaidaily.com/metro/...ffers-hope-for-autism-sufferers/shdaily.shtml
__________________________________​
Autism-like behaviours and germline transmission in transgenic monkeys overexpressing MeCP2
Nature (2016) doi:10.1038/nature16533
Received 31 May 2015 Accepted 14 December 2015 Published online 25 January 2016

http://www.nature.com/nature/journal/vaop/ncurrent/full/nature16533.html
 
.
CSNS First Drift Tube Linac Completes Beam Commissioning
Jan 26, 2016

The first tank of the Drift Tube Linac (DTL-1) of the China Spallation Neutron Source (CSNS) completed its beam commissioning on January 20. The beam commissioning lasted for twelve days, and on January 18, the beam reached the end of the first DTL tank with a peak current of 18 mA at 21.6 MeV, a transmission rate of 100% within the error of the Current Transformer. The success of CSNS DTL-1 is an important milestone of the CSNS project.

W020160126599159856579.jpg

CSNS DTL-1 (Image by IHEP)

CSNS First Drift Tube Linac Completes Beam Commissioning---Chinese Academy of Sciences
 
.
Group develops environmentally friendly liquid battery
January 26, 2016 by Bob Yirka

56a779502269c.jpg

Schematic illustration of cell structure. Credit: Science Advances (2016). DOI: 10.1126/sciadv.1501038

(Tech Xplore)—A small team of researchers at Fudan University, in China has developed a liquid battery that is more environmentally friendly than others of its kind. In their paper published in the journal Science Advances, the team describes the idea for their battery, the parts of it that have been tested already and its many positive attributes.

Because of the large scale nature of power storage for large solar or wind collection schemes, liquid batteries are used, but to date, none of those developed are environmentally friendly or safe for those in the immediate area (most contain components that are flammable, toxic, corrosive or need to be kept in a very hot environment). For that reason scientists continue to look for better alternatives. In this new effort, the team in China reports that they have developed an environmentally friendly Li (or Na) ion battery that is not just kinder to the environment, but has faster electrode kinetics and an extremely long life.

The battery (which is still in the proof-of-concept phase) is made using triiodide ions and a water-soluble iodide to make a cathode which is dissolved in a water based electrolyte that has either lithium or sulfur ions in it, an anode that is solid and made of a polymer of imide monomers, and a polymer membrane that sits between the anode and cathode to allow for diffusing ions. The creative team notes that neither the anode or cathode or the electrolytes rely on the use of metals, which makes the battery much nicer on the environment. They also note that testing revealed it capable of carrying out 50,000 cycles, which far surpasses other conventional batteries. It can also be discharged or charged as quickly as just 6.6 seconds, which is also much better than conventional batteries, and puts it in competition with super-capacitors. They also calculated that versions of their battery would have energy densities of between 63.8 and 65.3 watt hours per kilogram, which is in the same ballpark as other mass storage liquid batteries.

The team is not sitting on its laurels, they plan to continue their research to find ways to make such batteries bigger and with improved energy densities. Also, it is still not clear if the battery would be economically feasible.


More information: X. Dong et al. Environmentally-friendly aqueous Li (or Na)-ion battery with fast electrode kinetics and super-long life, Science Advances (2016). DOI: 10.1126/sciadv.1501038

Abstract
Current rechargeable batteries generally display limited cycle life and slow electrode kinetics and contain environmentally unfriendly components. Furthermore, their operation depends on the redox reactions of metal elements. We present an original battery system that depends on the redox of I−/I3− couple in liquid cathode and the reversible enolization in polyimide anode, accompanied by Li+ (or Na+) diffusion between cathode and anode through a Li+/Na+ exchange polymer membrane. There are no metal element–based redox reactions in this battery, and Li+ (or Na+) is only used for charge transfer. Moreover, the components (electrolyte/electrode) of this system are environment-friendly. Both electrodes are demonstrated to have very fast kinetics, which gives the battery a supercapacitor-like high power. It can even be cycled 50,000 times when operated within the electrochemical window of 0 to 1.6 V. Such a system might shed light on the design of high-safety and low-cost batteries for grid-scale energy storage.

© 2016 Tech Xplore

Group develops environmentally friendly liquid battery
 
.
Invisible ink for secret data, product and document security
January 26, 2016

invisibleink.gif

Ciphers and invisible ink – many of us experimented with these when we were children. A team of Chinese scientists has now developed a clever, high-tech version of "invisible ink". As reported in the journal Angewandte Chemie, the ink is based on carbon nitride quantum dots.

Read more->http://phys.org/news/2016-01-invisible-ink-secret-product-document.html

More information: Zhiping Song et al. Invisible Security Ink Based on Water-Soluble Graphitic Carbon Nitride Quantum Dots, Angewandte Chemie International Edition (2016). DOI: 10.1002/anie.201510945
 
.
CaO makes the graphene hierarchy for high-power lithium-sulfur batteries
January 26, 2016

56a76a31c37a5.jpg

Porous Graphene Casted on CaO template

Structural hierarchy is the cornerstone of the biological world, as well as the most important lesson that we have learned from nature to develop ingenious hierarchical porous materials for various applications in energy conversion and storage. Recently, a research group from China, led by Prof. Qiang Zhang in Tsinghua University, has developed a novel kind of hierarchical porous graphene (HPG) via a versatile chemical vapor deposition (CVD) on CaO templates for high-power lithium-sulfur (Li-S) batteries. This work is published in the journal Advanced Functional Materials.

"Due to the urgent demand for sustainable energy systems and portable energy storage devices, the Li-S battery has been cited as the most promising alternative for next-generation energy storage devices, due to its high theoretical energy density of 2600 Wh kg-1, low cost, and eco-friendliness," said Prof. Zhang. "Despite these advantages, the practical application still suffers from a formidable challenge due to the intrinsic insulation of sulfur and lithium sulfides, the dissolution of polysulfides with a shuttle effect, and the huge volume change of cathode materials during operation."

Read more->http://phys.org/news/2016-01-cao-graphene-hierarchy-high-power-lithium-sulfur.html

More information: 10.1002/adfm.201503726 Cheng Tang et al. CaO-Templated Growth of Hierarchical Porous Graphene for High-Power Lithium-Sulfur Battery Applications, Advanced Functional Materials (2016). DOI: 10.1002/adfm.201503726

Nanowerk's Nanotechnology Spotlights also featured the same paper,
Link: http://www.nanowerk.com/spotlight/spotid=42439.php
 
. .
Study reveals why giant star clusters could be home to variously aged star populations
Source: Xinhua 2016-01-28 03:48:35

LONDON, Jan. 27 (Xinhua) -- A team of Chinese and U.S. researchers has found evidence to explain why globular clusters can somehow bear second or even third sets of thousands of sibling stars, instead of having all their stellar progeny at once, according to a study published online Wednesday in the journal Nature.

Globular clusters are spherical, densely packed groups of stars orbiting the outskirts of galaxies. Astronomers had long thought globular clusters formed their millions of stars in bulk at around the same time, with each cluster's stars having very similar ages, much like twin brothers and sisters. Yet the recent discoveries of young stars within old globular clusters have scrambled this tidy picture.

Using observations by the Hubble Space Telescope, the team, led by researchers at the Kavli Institute for Astronomy and Astrophysics (KIAA) at Peking University, focused their attention on young and intermediate-aged clusters found in two nearby dwarf galaxies, collectively called the Magellanic Clouds.

The team found young populations of stars within globular clusters that have apparently developed courtesy of star-forming gas flowing in from outside of the clusters themselves.

This developing method stands in contrast to the conventional idea of the clusters' initial stars shedding gas as they age in order to spark future rounds of star birth, according to the study.

"Our study suggests the gaseous fuel for these new stellar populations has an origin that is external to the cluster, rather than internal," said study lead author Chengyuan Li, an astronomer at the KIAA.

The discovery "offers new insight on the problem of multiple stellar populations in star clusters," said Li. That means globular clusters appear capable of "adopting" baby stars - or at least the material with which to form new stars - rather than creating more "biological" children as parents in a human family might choose to do.

The team thus proposes that globular clusters can sweep up stray gas and dust they encounter while moving about their respective host galaxies.

"We have now finally shown that this idea of clusters forming new stars with accreted gas might actually work," said Richard de Grijs, co-author of the study.

Future studies will aim to extend the findings to other Magellanic Cloud as well as Milky Way globular clusters, according to the team.

________________________________________​

Stellar parenting: Giant star clusters make new stars by 'adopting' stray cosmic gases
A new study reveals why globular clusters can be home to differently aged populations of stars

The Kavli Foundation
107502_web.jpg

A portrait of the massive globular cluster NGC 1783 in the Large Magellanic Cloud taken by the Hubble Space Telescope. This dense swarm of stars is located about 160,000 light years from Earth and has the mass of about 170,000 Suns. A new study by astronomers from the Kavli Institute for Astronomy and Astrophysics at Peking University, the National Astronomical Observatories of the Chinese Academy of Sciences, Northwestern University, and the Adler Planetarium suggests the globular cluster swept up stray gas and dust from outside the cluster to give birth to three different generations of stars.
Credit
ESA/Hubble & NASA. Acknowledgement: Judy Schmidt (geckzilla.com)

Among the most striking objects in the universe are the dense, glittering swarms of stars known as globular clusters. Astronomers had long thought globular clusters formed their millions of stars in bulk at around the same time, with each cluster's stars having very similar ages, much like twin brothers and sisters. Yet the recent discoveries of young stars within old globular clusters have scrambled this tidy picture.

Instead of having all their stellar progeny at once, globular clusters can somehow bear second or even third sets of thousands of sibling stars. Now a new study led by researchers at the Kavli Institute for Astronomy and Astrophysics (KIAA) at Peking University, and including astronomers at the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC), Northwestern University, and the Adler Planetarium, might explain these puzzling, successive stellar generations.

Using observations by the Hubble Space Telescope, the research team has for the first time found young populations of stars within globular clusters that have apparently developed courtesy of star-forming gas flowing in from outside of the clusters themselves. This method stands in contrast to the conventional idea of the clusters' initial stars shedding gas as they age in order to spark future rounds of star birth.

The study is publishing today in the journal Nature.

"This study offers new insight on the problem of multiple stellar populations in star clusters," said study lead author Chengyuan Li, an astronomer at KIAA, NAOC and affiliated with the Chinese Academy of Sciences' Purple Mountain Observatory. "Our study suggests the gaseous fuel for these new stellar populations has an origin that is external to the cluster, rather than internal."

In a manner of speaking, globular clusters appear capable of "adopting" baby stars -- or at least the material with which to form new stars -- rather than creating more "biological" children as parents in a human family might choose to do.

"Our explanation that secondary stellar populations originate from gas accreted from the clusters' environments is the strongest alternative idea put forward to date," said Richard de Grijs, also an astronomer at KIAA and Chengyuan's Ph.D. advisor. "Globular clusters have turned out to be much more complex than we once thought."

Globular clusters are spherical, densely packed groups of stars orbiting the outskirts of galaxies. Our home galaxy, the Milky Way, hosts several hundred. Most of these local, massive clusters are quite old, however, so the KIAA-led research team turned their attention to young and intermediate-aged clusters found in two nearby dwarf galaxies, collectively called the Magellanic Clouds.

Specifically, the researchers used Hubble observations of the globular clusters NGC 1783 and NGC 1696 in the Large Magellanic Cloud, along with NGC 411 in the Small Magellanic Cloud. Scientists routinely infer the ages of stars by looking at their colors and brightnesses. Within NGC 1783, for example, Li, de Grijs and colleagues identified an initial population of stars aged 1.4 billion years, along with two newer populations that formed 890 million and 450 million years ago.

What is the most straightforward explanation for these unexpectedly differing stellar ages? Some globular clusters might retain enough gas and dust to crank out multiple generations of stars, but this seems unlikely, said study co-author Licai Deng of NAOC and Chengyuan's second Ph.D. advisor.

"The most massive stars that form in a globular cluster only live about 10 million years before exploding as supernovae, which blow away the remaining gassy, dusty fuel required for making new stars," Deng said.

The KIAA-led research team proposes that globular clusters can sweep up stray gas and dust they encounter while moving about their respective host galaxies. The theory of newborn stars arising in clusters as they "adopt" interstellar gases actually dates back to a 1952 paper. More than a half-century later, this once speculative idea suddenly has key evidence to support it.

"We have now finally shown that this idea of clusters forming new stars with accreted gas might actually work," said de Grijs, "and not just for the three clusters we observed for this study, but possibly for a whole slew of them." Future studies will aim to extend the findings to other Magellanic Cloud as well as Milky Way globular clusters.

Other members of the research team include Yu Xin and Yi Hu of NAOC, Aaron M. Geller of Northwestern University and the Adler Planetarium, and Claude-André Faucher-Giguère of Northwestern University.

###

The research is funded, in part, by the National Natural Science Foundation of China.

Stellar parenting: Giant star clusters make new stars by 'adopting' stray cosmic gases | EurekAlert! Science News
 
.
World's oldest tea remains discovered on ancient trade route
Residues found in burial pits near tomb of Han dynasty emperor Liu Qi shows plant was being transported along Silk Road route over 2,000 years ago
  • Agence France-Presse
  • Thursday 28 January 2016 17.31 GMT Last modified on Thursday 28 January 2016 23.14 GMT
2160.jpg

Pamir mountains in western Asia have some of the world’s most highly elevated roads and are believed to have formed part of the ancient trade route. Photograph: Jim Richardson/Corbis

The tomb of a Chinese emperor who lived more than 2,100 years ago has yielded the oldest remains of tea, said researchers who used it to re-date part of the ancient Silk Road network of Asian trade routes.

The plant remains were retrieved from burial pits around the tomb of Liu Qi, the fourth emperor of the Han dynasty who lived between 188BC and 141BC, and his wife, according to research by a team of academics from China and Britain, published in the journal Scientific Reports.

The oldest written reference to tea is from 59BC. And the oldest physical remains ever discovered previously were hundreds of years younger than the new find – dating from the northern Song Dynasty (AD960-AD1,127).

“Our study reveals that tea was drunk by Han Dynasty emperors as early as 2,100 years BP [before present],” wrote the team.

They compared this tea to residues unearthed among burial artefacts at Gurgyam cemetery in Tibet, and dated to about the second or third century AD.

This revealed that tea, which does not grow in Tibet, was already being transported from China to central Asia and the Tibetan Plateau several hundred years earlier than previously recorded, said the researchers.

“This indicates that one branch of the Silk Road passed through western Tibet at that time,” they said. The previous oldest record of tea having been carried along the Silk Road into Tibet, central Asia or southern Asia from Chia, was from the Tang Dynasty (AD618-AD907).

“These data indicate that tea was part of trade of luxury products, alongside textiles, that moved along the Silk Road around 2,000 years ago and were traded up into Tibet,” the study said.

Tea today is considered the most popular drink after water – drunk regularly by three-quarters of the world’s population.

The plant remains were too decayed to be unequivocally identified as leaves and buds, so the team used molecular analysis to identify what they were. The tea was most likely from the Camellia plant, said the study.

World's oldest tea remains discovered on ancient trade route | Life and style | The Guardian
 
.

Pakistan Defence Latest Posts

Pakistan Affairs Latest Posts

Back
Top Bottom