China Science & Technology Forum

[JSCh]

JANUARY 23, 2019
Gene-edited disease monkeys cloned in China
by Science China Press

Five Cloned Monkeys from Somatic Cells of a Gene-edited Monkey with Disease Phenotypes Credit: ©Science China Press

The first cohort of five gene-edited monkey clones made from fibroblasts of a monkey with disease phenotypes were born recently at the Institute of Neuroscience (ION) of the Chinese Academy of Sciences (CAS) in Shanghai. The expression of BMAL1, a core circadian regulatory transcription factor, was knocked out in the donor monkey using CRISPR/Cas9-mediated gene editing at the embryo stage, and the fibroblasts of the donor monkey were used to clone five monkeys using the method of somatic cell nuclear transfer, the same method that generated Zhong Zhong and Hua Hua, the first two cloned monkeys, last year. This major advance, reported in two articles in the journal National Science Review on January 24, demonstrates that a population of customized gene-edited macaque monkeys with uniform genetic background will soon be available for biomedical research.

The first article describes the generation of gene-edited donor monkeys using CRISPR-Cas9 to edit the BMAL1 gene of in vitro fertilized monkey embryos. These monkeys exhibited a wide range of circadian disorder phenotypes, including reduced sleep time, elevated night-time locomotive activities, dampened circadian cycling of blood hormones, increased anxiety and depression, as well as schizophrenia-like behaviors. "Disorders of circadian rhythm could lead to many human diseases, including sleep disorders, diabetes mellitus, cancer and neurodegenerative diseases. Our BMAL1 knock-out monkeys could thus be used to study the disease pathogenesis as well as therapeutic treatments," says Hung-Chun Chang, senior author and investigator of the Chinese Academy of Sciences Institute of Neuroscience.

The second article describes the cloning of macaque monkeys from the fibroblast of a BMAL1-knockout monkey using the method of somatic cell nuclear transfer. In this method, the researchers removed the nucleus from a monkey oocyte (egg cell) and replaced it with another nucleus from a fibroblast, a differentiated somatic (body) cell. This reconstructed egg then developed into an embryo that carries the genes of the replacement nucleus.

The embryo was then transferred to the womb of a surrogate female monkey that later gave birth to the cloned monkey. In the previous work, Zhong Zhong and Hua Hua were generated by using fibroblasts from an aborted fetus. The present work succeeded in using fibroblasts from a young adult gene-edited donor monkey with disease phenotypes. "Our approach is to perform gene editing in fertilized embryos to first generate a group of gene-edited monkeys, and then select one monkey that exhibits correct gene editing and most severe disease phenotypes as the donor monkey for cloning by somatic cell nuclear transfer," says Qiang Sun, senior author of the paper and director of ION's Nonhuman Primate Research Facility. "We believe that this approach of cloning gene-edited monkeys could be used to generate a variety of monkey models for gene-based diseases, including many brain diseases, as well as immune and metabolic disorders and cancer." The researchers plan to continue improving the technique in order to increase the efficiency of cloning. The group is expecting more macaque clones carrying disease-causing gene mutations to be generated in the coming years.

The Institute of Neuroscience, CAS is following strict international guidelines for animal research. "This work required coordinated efforts of many laboratories, and serves as a clear example of the efficient team work that is highly emphasized by CAS" says Mu-ming Poo, A co-author on both studies, who directs the Institute of Neuroscience and helps to supervise the project. "This line of research will help to reduce the amount of macaque monkeys currently used in biomedical research around the world." "Without the interference of genetic background, a much smaller number of cloned monkeys carrying disease phenotypes may be sufficient for pre-clinical tests of the efficacy of therapeutics," Poo says.

More information:

1. Qiu, P. et al: "BMAL1 knockout macaque monkeys display reduced sleep and psychiatric disorders". National Science Review. DOI: 10.1093/nsr/nwz002 , https://academic.oup.com/nsr/article-lookup/doi/10.1093/nsr/nwz002
2. Liu, Z. et al. "Cloning of a gene-edited macaque monkey by somatic cell nuclear transfer ". National Science Review. DOI: 10.1093/nsr/nwz003 , https://academic.oup.com/nsr/article-lookup/doi/10.1093/nsr/nwz003

Gene-edited disease monkeys cloned in China | MedicalXpress

 

[JSCh]

Chinese airship sets new record in measuring high-altitude vapor
CGTN
Published on Jan 23, 2019

The second Qinghai-Tibet research mission has set a new record by reaching 6,200 meters for high-altitude water vapor observations. This is the first time in the world that a floating airship has been used to measure water at such high altitudes.

 

[JSCh]

Amazing research by Chinese Academy of Sciences in 2018
Source: Xinhua| 2019-01-24 20:45:02|Editor: mmm

BEIJING, Jan. 24 (Xinhua) -- The Chinese Academy of Sciences (CAS) has made many research advances in 2018, from the depths of the ocean, to far beyond the universe. Here are some of the highlights:

1. The CAS accomplished several key tasks for the Chang'e-4 mission. More than 20 critical instruments and materials crucial to Chang'e-4's safe landing, ongoing operation on the lunar surface and scientific exploration were developed.

2. CAS researchers cloned the world's first macaques from somatic cells by the method that made Dolly the sheep. It makes research with customizable populations of genetically uniform monkeys a possibility.

3. GV-971 drug brings hope for Alzheimer's treatment. Sodium oligomannate (GV-971), an innovative, orally administered drug for treating Alzheimer's disease, completed its phase III clinical trial, the last test before reaching the market in July 2018. It is the fruit of a 21-year research effort by a team led by the Ocean University of China, CAS and Green Valley Pharmaceutical Co., Ltd.

4. Majorana Bound States in iron-based superconductor was observed. A CAS research team observed Majorana bound states in an iron-based superconductor for the first time -- a major advance for building a future stable, scalable, and fault-tolerant topological quantum computer.

5. China Spallation Neutron Source (CSNS) and Wuhan P4 Laboratory were put into service. The CSNS is the country's first and world's fourth pulsed spallation neutron source, and passed national acceptance on Aug. 1, 2018. The Wuhan P4 Laboratory is China's first national biosafety level 4 laboratory, helping the country play a more active role in global public health.

6. The world's first artificial single-chromosome eukaryotic cell were created. Qin Zhongjun, a CAS molecular biologist, together with his collaborators, created the world's first eukaryotic cell containing only a single chromosome.

7. Rice molecular design breeding helps variety upgrade in China. "Zhongke 804," a new rice variety developed by CAS academician Li Jiayang showed excellent performance in 2018. It is outstanding in yield, blast resistance, rice quality, lodging resistance and head-milled rice rate.

8. Eight new satellites joined the Beidou network. Four pairs of Beidou Navigation System satellites manufactured by the CAS were launched into space in 2018. Each pair of satellites was launched from the Xichang Satellite Launch Center by one rocket into medium Earth orbit.

9. Multiple high-end scientific instruments were developed. A series of high-performance streak cameras were developed by the CAS, a breakthrough in key technologies such as the design of electronic optical systems and the production of high-performance photocathode.

10. The earliest human occupation of the Tibetan Plateau dates to 40,000 years ago. Archaeologists from the CAS reported the oldest and highest early Stone Age archaeological site yet known anywhere in the world in November 2018. The discovery of the Nwya Devu site has yielded the earliest record of human responses to high-altitude challenges and the eventual conquest of the extreme environment.

11. A cold atomic clock in the Tiangong-2 space lab. A cold atomic space clock, developed by the CAS, was launched into space with Tiangong-2. It is the first cold atomic clock in the world operating in orbit and carrying out scientific experiments.

12. Breakthroughs in stem cell and regenerative medicine technology and equipment. Regenerative medicine experts at the CAS and doctors at Nanjing Drum Tower Hospital used human umbilical cord mesenchyme stem cells to rehabilitate a woman's damaged ovary, enabling her to give birth to a healthy boy on Jan. 12, 2018.

 

[JSCh]

Zhou Huanping's and Yan Chunhua's teams improve the operational stability for perovskite solar cells
Peking University, Jan. 24, 2019

Long-term stability is the most intractable issue during the commercialization of perovskite solar cells (PSCs). The intrinsic degradation of perovskite materials into Pb0 & I0 defects seriously restricts the long-term durability of PSCs. Researchers from Professor Zhou Huanping’s team in the College of Engineering, PKU and Professor Yan Chunhua’s team in the College of Chemistry & Molecular Engineering proposed a new mechanism to solve this problem.

They introduced Eu3+-Eu2+ ion pair redox shuttle into perovskite layer and achieved selectively oxidation of Pb0 and reduction of I0 defects simultaneously in a cyclical transition. The resultant PSCs achieved substantially improved efficiency and long-term durability. The related paper was published in the world's top academic journal Science on January 18, 2019, entitled “A Eu3+-Eu2+ ion redox shuttle imparts operational durability to Pb-I perovskite solar cells” (doi: 10.1126/science. aau5701).

Converting solar energy into electrical energy directly via solar cells, which is based on photovoltaic effect, is one of the most effective methods for solar energy application. Devices lifetime and power conversion efficiency (PCE) are the two key factors determining the final cost of the electricity that solar cells generate. The certified PCE of perovskite solar cells has rapidly reached 23.7% over the past few years, which surpassed the commercialized Cu(In,Ga)Se2 and polycrystalline silicon solar cells. The solution-processed feature imparts huge cost advantage to PSCs and gains tremendous attentions of worldwide researchers.

However, poor device stability under operating conditions prevents the perovskite photovoltaics from occupying even a tiny market share. The components in organic-inorganic halide perovskite materials including I–, Pb2+, MA+ and FA+ are large and with low valence ions compared with traditional inorganic photovoltaic materials such as silicon (IV group) and Cu(In,Ga)Se2 solar cells (I-III-VI group). These soft ions construct soft crystal lattice prone to deform and vulnerable to various aging stresses including electric field, thermal stress, oxygen, moisture, and ultraviolet (UV) exposure.

According to the researchers, the lifetime of PSCs can be prolonged to some extent by the maturing encapsulation methods. However, some aging stresses cannot be avoided during device operation, including light illumination, electric field, and thermal stress, upon which both I– and Pb2+ in perovskites become chemically reactive to initiate the decomposition. On the one hand, I– is easily oxidized to I0, which not only serves as carrier recombination centers but also initiates chemical chain reactions to accelerate the degradation in perovskite layers. On the other hand, Pb2+ is prone to be reduced to metallic Pb0, which has been widely observed in Pb halide perovskite films. Metallic Pb0 is an important deep-level defect that severely degrades the efficiency of perovskite optoelectronic devices including solar cell, light-emitting diodes, photodetectors. This mild but irreversible degradation, which would be accumulated day by day, might be the most intractable issue for perovskite materials and the biggest obstacle for achieving operational durability of PSCs. It is urgent and essential to solve this fundamental and intrinsic degradation.

Figure 1. Proposed mechanism diagram of cyclical elimination of Pb0 and I0 defects and regeneration of Eu3+-Eu2+ ion pair redox shuttle
​

To solve this intrinsic degradation issue, researchers from Zhou Huanping team, Yan Chunhua team and collaborators proposed a new mechanism and demonstrated constant elimination of Pb0 & I0 defects simultaneously in PSCs over lifetime of PSCs, which leads to exceptional stability improvement and high PCE through incorporation of the ion pair of Eu3+ (f6) ↔ Eu2+ (f7) as the redox shuttle. In this cyclic redox transition, Pb0 defects could be oxidized by Eu3+ (2Eu3+ + Pb0 → 2Eu2+ + Pb2+), while I0 defects could be reduced by Eu2+ (Eu2+ + I0 → Eu3+ + I– ) at same time. The Eu3+-Eu2+ redox shuttle is not consumed during device operation, probably because of its nonvolatility and the suitable redox potential in this cyclic transition. Thus, the champion PCE of the corresponding device was promoted to 21.52% (certified, 20.52%) with negligible current density-voltage (J-V) hysteresis. Devices with the Eu3+-Eu2+ redox shuttle exhibited excellent thermal and light stability. The devices retained 92% and 89% of the peak PCE under 1-sun continuous illumination or heating at 85°C for 1500 hours and 91% of the original stable PCE after maximum power point tracking for 500 hours, respectively. This method provides a universal solution to the inevitable degradation issue of perovskite optoelectronic devices including solar cells, LED, photo-detectors and so on. This concept can also be extended to other inorganic semiconductor materials and devices which face similar instability problems.

Figure 2: Long-term stability and original performance evolution of PSCs​

The first author of this paper is Ph.D. candidate, Wang Ligang (2014), co-supervised by Yan group (College of Chemistry) and Zhou group (College of Engineering). The corresponding authors are Professor Zhou Huanping, Professor Yan Chunhua and Professor Sun Lingdong. Collaborators include researchers from Professor Huang Bolong team (Hong Kong University of Science and Technology) and the Chen Qi team (Beijing Institute of Technology). The work was jointly supported by the National Natural Science Foundation of China, the Ministry of Science and Technology, Beijing Municipal Science and Technology Project, Beijing National Laboratory for Molecular Sciences, Beijing Key Laboratory for Theory and Technology of Advanced Battery Materials.

Edited by: Huang Weijian
Source: College of Engineering



Zhou Huanping's and Yan Chunhua's teams improve the operational stability for perovskite solar cells_Peking University

Ligang Wang, Huanping Zhou, Junnan Hu, Bolong Huang, Mingzi Sun, Bowei Dong, Guanghaojie Zheng, Yuan Huang, Yihua Chen, Liang Li, Ziqi Xu, Nengxu Li, Zheng Liu, Qi Chen, Ling-Dong Sun, Chun-Hua Yan. A Eu3+-Eu2+ ion redox shuttle imparts operational durability to Pb-I perovskite solar cells. Science (2019). DOI: 10.1126/science.aau5701​

 

[cirr]

25 January 2019

Battling AI algorithm tested on a quantum computer for first time

Quantum algorithms may be on the horizon
Colin Anderson Productions/Getty

By Donna Lu

Machine learning is growing ever more sophisticated, thanks to algorithms which pit two artificial intelligences against each other. These algorithms, known as generative adversarial networks (GANs), have already been used to create art, crack encryption codes, and produce uncannily real pictures of faces and animals.

Researchers have now combined GANs with another hot technology: quantum computing. Luyan Sun at Tsinghua University in Beijing, China and his colleagues have created a GAN on a quantum circuit.

Quantum algorithms

GANs are formed of two neural networks, the generator …

https://www.newscientist.com/articl...-tested-on-a-quantum-computer-for-first-time/

清华团队首次实现量子GAN

新智元

2019-01-28 15:49

量子计算机虽然强大，但应用领域有限。清华叉院孙麓岩团队在超导电路上实现了量子生成对抗网络，精度高达98.8%，这项工作有望证明量子计算机在图像生成等领域超越经典计算机，将是量子机器学习的又一里程碑。

本文来自微信公众号：新智元（ID：AI_era），来源：Science Advances、New Scientist，编辑：金磊、闻菲、张乾

量子机器学习的新里程碑！

清华大学孙麓岩团队提出了“量子版”的生成对抗网络，并且证明了与经典的对应方法相比，具有潜在的“指数级”优势。

最近，孙麓岩团队的研究登上了Science Advances，论文首次介绍了超导量子电路中量子生成对抗学习的原理证明及实验演示。

研究结果表明，经过几轮对抗学习，可以训练一个量子态的发生器，对量子信道模拟器输出的量子数据进行统计复制，并且具有98.8%的高保真度，使得鉴别器无法区分真实数据和生成数据。

值得注意的是，证明“量子霸权”通常被认为需要至少50个量子比特，但该团队的研究使用的系统只有一个量子比特。

首次证明量子计算能利用GAN

生成对抗网络（GAN）由两个神经网络构成，即生成器和鉴别器。

生成器会生成数据，例如人脸图片；鉴别器既可以得到真实数据，也可以得到生成器创建的假数据，而且必须分辨出真假。它俩经过多轮的循环，最终生成器得到了更新，学会了如何产生更为逼真的图像，使得鉴别器无法再区分其真假。


而GAN也是近年来机器学习领域最令人兴奋的突破之一。它在图像、视频生成等各种具有挑战性的任务中表现突出，例如，能够生成无比逼真的人脸照片，以假乱真。

GAN生成的照片

从理论上讲，量子计算机在解决某些问题（如分解大数）方面比普通计算机具有速度优势。

“但就目前的技术水平而言，量子计算机还无法达到这一优势。”孙麓岩说。

研究人员认为，量子计算机上的GAN也可能具有这样的速度优势，但他们仍然需要明确证明这一点。

于是，利用量子生成器和鉴别器制造出一种量子GAN，成为证明“量子霸权”的又一案例。

量子生成对抗网络QGAN：准确率98.8%

孙麓岩团队实验性地演示了生成对抗网络的量子版本——QGAN，其中输入和输出数据都是量子比特。

生成器G由一个超导电路构成，能够生成一个随机纯量子态的集合ρ，模拟真正的量子数据σ。其中，输入的量子数据由一个数字量子比特信道模拟器随机生成。

鉴别器D则由一个专门衡量相关映射的量子设备构成，能够生成衡量映射的结果M。

接下来的过程就与普通的生成对抗网络（GAN） 一样，生成器G不断生成虚拟数据ρ，然后鉴别器D则不断生成衡量ρ和衡量σ的结果，试图区分ρ 和σ，反过来优化生成器的生成结果，最终致使D无法区分ρ 和 σ。

量子生成对抗网络QGAN的示意图：(a) 量子生成器G和量子鉴别器D，G生成一个模拟量子态ρ，真实量子态σ则由模拟器随机生成；(b) D得到输入数据后，通过衡量机制判断模拟数据ρ 和真实量子态σ 的不同。

研究人员构建的这个量子GAN算法执行示意图如下：

σ 作为原始量子数据，ρ 作为模拟量子态分布，所以是一个概率分布。其中，衡量结果的差异β 和γ 通过FPGA阵列实现。

QGAN算法的实验协议

实验证实了生成器确实能够学会数据量子数据的模式（pattern），并生成几乎与真实量子数据一样的量子态。

不仅如此，研究人员在论文中指出，他们最高能够取得98.8%的准确率。

量子计算机有望在图像生成上实现量子霸权

研究人员得出结论，由于QGAN实验中既不需要量子随机存储设备，也不需要通用量子计算设备或对任何参数进行微调，因此可以认为，在不远的未来，量子设备就能实现可用的、含有噪音的中型量子应用。

什么是“含有噪音的中型量子”？去年，加州理工大学理论物理学家、“量子霸权 ”概念提出者 John Preskill 指出，在实现 50~100 量子比特的中型量子计算机后，人类就可以用其探索更多经典计算机无法探索的研究领域，也将由此迈进一个新的量子技术发展期，他将其称之为“含噪声的中型量子” (Noisy Intermediate-Scale Quantum, NISQ) 时代。

计算机体系结构顶会 MICRO 2017 的最佳论文奖，授予了这样一项工作，论文提出了一种控制超导量子计算机的微体系结构，首次有机连接了量子软件和硬件，让传统处理器的设计技术能够为量子控制处理器所用。

清华大学的这项实验工作的意义就在于，首次在超导量子电路（属于NISQ设备）上实现了量子GAN，鉴于GAN在图像生成等应用上的强大性能，这有望实现图像生成的“量子霸权”，也即用量子计算机生成图像比经典计算机更快更强。

结合MICRO 2017的最佳论文奖研究，或许能够加速清华大学这项工作实现图像量子霸权。想一想，不是很令人激动吗？

论文地址：

http://advances.sciencemag.org/content/5/1/eaav2761

 

[JSCh]

PUBLIC RELEASE: 30-JAN-2019
The 'Batman' in hydrogen fuel cells
Scientists find way to help fuel cells work better, stay clean in the cold

UNIVERSITY OF SCIENCE AND TECHNOLOGY OF CHINA

​

The catalyst developed here shows great potential to thoroughly guard the fuel cell during not only the continuous operation but also during frequent cold-start periods even under extremely cold conditions. CREDIT: Junling Lu's research group

In a study published in Nature on January 31st, researchers at the University of Science and Technology of China (USTC) report advances in the development of hydrogen fuel cells that could increase its application in vehicles, especially in extreme temperatures like cold winters.

Hydrogen is considered one of the most promising clean energy sources of the future. Hydrogen fuel cell vehicles use hydrogen as fuel, which has high energy conversion efficiency, and zero emissions. But the development of hydrogen fuel cells faces many challenges, including the issue of carbon-monoxide (CO) poisoning of the fuel cell electrodes. Currently, hydrogen is mainly derived from such processes as steam reforming of hydrocarbons, such as methanol and natural gas, and water gas shift reaction. The resulting hydrogen usually contains 0.5% to 2% of trace CO. As the "heart" of hydrogen fuel cell vehicles, fuel cell electrodes are easily "poisoned" by CO impurity gas, resulting in reduced battery performance and shortened life, which severely hampers the application fuel cells in vehicles.

Earlier research has identified a method, called preferential oxidation in CO in Hydrogen (PROX), as a promising way to on-board remove trace amounts of CO from hydrogen by using catalysts. However, existing PROX catalysts can only work in high temperatures (above room temperature) and within a narrow temperature range, making it impractical for civil applications, such as fuel cell vehicles, that must be reliable even in winter months (Fig. 1).

Now, a USTC team led by Junling Lu, professor at the Hefei National Laboratory for Physical Sciences at the Microscale, has designed a new structure of atomically dispersed iron hydroxide on platinum nanoparticles (Fig. 2) to efficiently purify hydrogen fuel over a broad temperature range of 198-380 Kelvin, which is approximately -103oF-224oF or -75oC-107oC. They also found that the material provided a thorough protection of fuel cells against CO poisoning during both frequent cold-starts and continuous operations in extremely cold temperatures.

"These findings might greatly accelerate the arrival of the hydrogen fuel cell vehicle era," said Prof. Lu.

"Our ultimate goal is to develop a cost-effective catalyst with high activity and selectivity that provides continuous on-board fuel cell protection and one that enables complete and 100% selective CO removal in a fuel cell that can be used for broader purposes," Prof. Lu adds.

One referee of the article commented: "When comparing with other catalyst systems reported in the literature, this reverse single-atom catalyst appears the best in terms of activity, selectivity, and stability in CO2-containing streams."



The 'Batman' in hydrogen fuel cells | EurekAlert! Science News

Lina Cao, Wei Liu, Qiquan Luo, Ruoting Yin, Bing Wang, Jonas Weissenrieder, Markus Soldemo, Huan Yan, Yue Lin, Zhihu Sun, Chao Ma, Wenhua Zhang, Si Chen, Hengwei Wang, Qiaoqiao Guan, Tao Yao, Shiqiang Wei, Jinlong Yang & Junling Lu . Atomically dispersed iron hydroxide anchored on Pt for preferential oxidation of CO in H2. Nature (2019). DOI: 10.1038/s41586-018-0869-5​

 

[JSCh]

PUBLIC RELEASE: 31-JAN-2019
China launched world's first rocket-deployed weather instruments from unmanned semi-submersible vehicle
INSTITUTE OF ATMOSPHERIC PHYSICS, CHINESE ACADEMY OF SCIENCES

​

An unmanned semi-submersible vehicle (USSV) developed by Chinese Academy of Sciences. The photo was taken at the first USSV sea trial in Bohai Bay on 13 June 2017. CREDIT: Siping Zheng

For the first time in history, Chinese scientists have launched a rocketsonde -- a rocket designed to perform weather observations in areas beyond the range of weather balloons -- from an unmanned semi-submersible vehicle (USSV) that has been solely designed and specially developed by China for this task.

The results of initial sea trials conducted in 2018 were published in Advances in Atmospheric Sciences on 31 Jan 2019.

Obtaining accurate meteorological and oceanographic (METOC) data requires conducting ocean-based meteorological and oceanographic sampling of an extensive marine environment that covers nearly three-quarters of the Earth's surface. Traditionally this has been achieved by using ocean-based observation platforms such as ships and buoys, as well as satellites and aircraft. However, because these methods are expensive and/or logistically impractical to deploy over a wide -- and often environmentally hostile -- area, the data collected is patchy and therefore unreliable for marine and meteorological research.

According to lead author, Hongbin Chen, a professor of atmospheric and marine science at the Institute of Atmospheric Physics, Chinese Academy of Sciences, radiosonde (a battery-powered telemetry instrument carried into the atmosphere usually by a weather balloon that records meteorological measurements and transmits them via radio to a ground receiver) is currently the principal method used to obtain the vertical distribution of meteorological data within the atmosphere, but the number of upper air sounding stations in the ocean is limited compared to land sites. Although both dropsonde weather balloons which are deployed from aircraft and record atmospheric data as they drop down to Earth, and driftsonde weather balloons containing meteorological instruments enclosed in a gondola --which depending on the pressure of the balloon, are capable of drifting in the stratosphere anywhere from five days to a few weeks or even months -- are routinely used over the ocean, these cannot meet the needs of marine weather (such as typhoon and fog) research, numerical prediction, marine atmospheric boundary layer (MABL) modeling and marine satellite product validation.

"Launched from a long-duration unmanned semi-submersible vehicle, with strong mobility and large coverage of the sea area, rocketsonde (meteorological rockets that are capable of launching weather instruments up to 8,000 meters into the atmosphere) can be used under severe sea conditions and will be more economical and applicable in the future," says Chen.

"The unmanned semi-submersible vehicle is an ideal platform for marine meteorological environmental monitoring, and the atmospheric profile information provided by rocketsonde launched from this platform can improve the accuracy of numerical weather forecasts at sea and in coastal zones," explains study co-author Dr Jun Li, a researcher at the Institute of Atmospheric Physics, CAS. "Similar to Argo (the broad-scale global array of profiling floats that measures temperature/salinity in the ocean) which provides profiles of Thermohaline current, rocketsonde can provide profiles of atmospheric temperature, humidity, pressure and wind observations."

In the future the researchers plan to use unmanned semi-submersible vehicles to provide a network of observations at sea that will extend weather sounding data over the ocean similar to that of the sounding network on land, says Chen, adding that they expect the unmanned semi-submersible vehicle observation network to provide three-dimensional observations of the internal structure of typhoons/hurricanes and to improve our ability to predict changes in a typhoons path or intensity.

"We are currently developing a new generation of USSVs which can carry various sensors relevant to marine science, including conductivity-temperature-depth, acoustic Doppler current profiler, and motion sensors to provide vertical profiles of the conductivity, water temperature, current velocity, and wave height and direction," says Chen. "With that, a new interconnected USSV meteorological and oceanographic (METOC) observation network system will be developed to improve the efficiency of collecting METOC observations and provide comprehensive data at the temporal and spatial scales required to answer relevant scientific questions."

By developing specially equipped USSVs that can record marine meteorological data in real-time over a wide area of the ocean that previously went largely unmonitored, the researchers hope to be able to fill some of the current meteorological and oceanographic data gaps, providing more robust data that will in turn help scientists to better predict and monitor weather events and oceanographic phenomena.



China launched world's first rocket-deployed weather instruments from unmanned semi-submersible vehicle | EurekAlert! Science News

 

[JSCh]

China's High Energy Photon Source Feasibility Study Report Approved
Jan 11, 2019

China's High Energy Photon Source (HEPS) project moved one step closer to reality with approval of the HEPS Feasibility Study Report by the National Development and Reform Commission, China' s top economic planning body, on Dec. 28, 2018.

HEPS will be one of the core facilities of Huairou Science City, located in Beijing's suburban Huairou District.

It will have a beam energy of 6 GeV and an ultra-low emittance ring-based synchrotron radiation light source, allowing China to join an elite global group of high energy synchrotron radiation light sources. It will offer strong support for research fields related to domestic needs and lead to revolutionary innovation in various industries.

Construction is expected to begin in 2019 and take 6.5 years. During Phase I, 14 beamlines, the accelerator and some other auxiliary buildings will be built.

The project was originally proposed in 2008 and listed as one of China' s large research infrastructure projects in the country' s 13th Five-year Plan in 2016.

Synchrotron radiation facilities are indispensable in numerous frontier research areas. The HEPS is a kilometer-scale, 6 GeV, ultralow- emittance storage-ring-based light source, planned to be built in Beijing. (Image by Institute of High Energy Physics of Chinese Academy of Sciences)



China's High Energy Photon Source Feasibility Study Report Approved---Chinese Academy of Sciences

'World's brightest light' project expected to start mid 2019
2019-02-01 16:14:04Ecns.cnEditor : Mo Hong'e

A video demonstration shows how the world's brightest synchrotron radiation light takes place. (Photo/Screenshot of CNS Video)

(ECNS) -- A project to build the world's brightest synchrotron radiation light source has passed review by national authorities, said the Institute of High Energy Physics (IHEP) of Chinese Academy of Sciences on Thursday.

Construction of the facility will start in middle of this year at Science and Technology Town located in Beijing's suburban Huairou District, and will be finished in six and a half years.

With an investment of 320 million yuan ($48 million), the Test Facility of High Energy Photon Source (HEPS-TF), the first R&D phase before construction of the facility, is expected to produce X-rays up to 300 keV in photon energy.

A synchrotron radiation light source uses electron-magnetic radiation usually produced by a storage ring.

The first phase will consist of accelerator chains, 14 beamlines and other auxiliary facilities.

To generate light of extreme brilliance, electrons will be accelerated nearly to the speed of light in several stages and forced to travel in a closed path.

 

[JSCh]

PUBLIC RELEASE: 6-FEB-2019
Nullifying protein YTHDF1 enhances anti-tumor response
Power of cancer immunotherapy expanded by improved antigen presentation

UNIVERSITY OF CHICAGO MEDICAL CENTER

Cancer immunotherapy--an approach that removes the barriers that protect cancer cells from a patient's immune system--has revolutionized the treatment of many cancer types. About 40 percent of melanoma patients, for example, respond to immunotherapy, enabling the immune system's T cells to attack cancer cells and take control of the disease.

In a study published in the February 6, 2019 issue of Nature, a University of Chicago-based team working in collaboration with scientists at Tsinghua University and the Chinese Academy of Sciences, demonstrates, in mice, that they can boost the tumor control rate from around 40 percent up to nearly 100 percent by opening up a parallel pathway.

This study, "Anti-tumor immunity controlled through mRNA m6A methylation and YTHDF1 in dendritic cells," relies on manipulating these cells, which are a crucial component of the immune system. The primary function of dendritic cells is to process antigens and present them to T cells. They act as messengers, connecting the innate and the adaptive immune systems.

But a protein known as YTHDF1 influences antigen processing by dendritic cells. This protein was discovered and characterized in 2015 by Chuan He, PhD, the John T. Wilson Distinguished Service Professor in chemistry, biochemistry and molecular biology, and the Institute for Biophysical Dynamics at the University of Chicago. YTHDF1 controls the level of proteases that destroy potential tumor antigens. This limits their presentation to T cells.

These limits were a problem, He said. But when he and his colleagues eliminated YTHDF1, the dendritic cells increased their ability to engulf peptides, degrade them and present them to T cells. This opened up a new and potentially effective approach to treatment of cancer in patients who do not respond well to checkpoint inhibitors.

"Once we combined YTHDF1 knock-out with the checkpoint inhibitor anti PD-L1, we got almost complete tumor control in a mouse model," He said. Instead of a 40 percent response, nearly 100 percent of treated mice with melanoma responded to anti-PD-L1.

The researchers confirmed that dendritic cells from mice that lacked YTHDF1 were more effective at antigen-presentation than dendritic cells from normal, wild-type mice. "Our data show that loss of YTHDF1 in dendritic cells attenuates antigen degradation and leads to improved cross-presentation and better cross-priming of CD8+ T cells," according to co- corresponding author Dali Han, PhD, now at the Beijing Institute of Genomics.

Together with gastroenterologist Marc Bissonnette, MD, associate professor of medicine at the University of Chicago, He's team performed an additional test using biopsies from human patients with colon cancer, a disease that is much less responsive to immunotherapy than melanoma. They found that tissue from patients with high levels of YTHDF1 had limited T cell infiltration, but patients with low levels of YTHDF1 had more T cell infiltrates. "This suggests that humans correlate nicely with our mouse data," He added.

"An important question in cancer treatment is 'how could we get better antigen presentation?'" according to co-author Ralph Weichselbaum, MD, the Daniel K. Ludwig Distinguished Service Professor and chairman of radiation oncology at the University of Chicago. "This study opens a lot of doors," he said. "It provides a whole new set of targets to the immune system, ranging from new sets of antigens to potential anti-cancer vaccines. This is the type of cross-divisional, interdisciplinary collaboration that could lead to unexpected discoveries."

This supports the notion that reduced YTHDF1 often coincides with the T cell inflamed tumor microenvironment, which is crucial for successful immunotherapy, the authors note. YTHDF1 could be a therapeutic target for immunotherapy in combination with emerging checkpoint inhibitors or dendritic cell vaccines.

"It will be really interesting to test how the human system works with potential dendritic cell vaccines or small molecule inhibitors that can suppress the activity of YTHDF1 in human cancer patients," according to corresponding author Meng Michelle Xu, PhD, a former member of the He and Weichselbaum laboratories.

"We have not yet seen any measurable toxicity, as far as we can tell, related to knocking down YTHDF1 in mice," He added. "At this point, this appears to be a very benign system. We hope to begin early testing in patients within one year."

###​

The National Key Research and Development Program of China, the Strategic Priority Research Program of the Chinese Academy of Sciences, the National Institutes of Health, The Ludwig Center at the University of Chicago, the National Natural Science Foundation of China, the National Science Fund for Excellent Young Scholars, the Science Foundation for Distinguished Young Scholars of China, and the National Science Foundation. Additional authors include Jun Liu, Chuanyuan Chen, Lihui Dong, Yi Liu, Renbao Chang, Xiaona Huang, Yuanyuan Liu, Jianying Wang, Bin Shen, Urszula Dougherty and Marc Bissonnette.



Nullifying protein YTHDF1 enhances anti-tumor response | EurekAlert! Science News

Dali Han, Jun Liu, Chuanyuan Chen, Lihui Dong, Yi Liu, Renbao Chang, Xiaona Huang, Yuanyuan Liu, Jianying Wang, Urszula Dougherty, Marc B. Bissonnette, Bin Shen, Ralph R. Weichselbaum, Meng Michelle Xu & Chuan He. Anti-tumour immunity controlled through mRNA m6A methylation and YTHDF1 in dendritic cells. Nature (2019). DOI: 10.1038/s41586-019-0916-x​

 

[JSCh]

Viewpoint: A Metamaterial for Superscattering Light
Yongmin Liu, Departments of Mechanical and Industrial Engineering and Electrical and Computer Engineering, Northeastern University, Boston, MA, USA
February 11, 2019• Physics 12, 14

A team has engineered a subwavelength structure that features a greatly enhanced capacity to scatter microwave light.

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APS/Alan Stonebraker​

Figure 1: Sketch of the superscatterer engineered by Chen, Zhang, and co-workers—a cylinder made of three concentric cylindrical metasurfaces separated by dielectric materials.

Light scattering is a common optical phenomenon, much like reflection, refraction, and absorption. Small molecules in the atmosphere scatter sunlight more efficiently at the shorter wavelengths of the solar spectrum, giving the sky its blue color on a clear day. And larger vapor droplets scatter light over the entire visible spectrum, lending clouds their white appearance. In general, the intensity and direction of the scattered light depend on its wavelength and on the characteristics of the scatterer—such as size, geometry, and refractive index. Researchers have tuned these characteristics to engineer structures that scatter light in specific—and often surprising—ways. Schemes for diminished scattering, or “cloaking,” have been proposed or realized [1, 2], as have schemes that selectively enhance scattering in a desired direction [3–5]. Now, a team led by Hongsheng Chen at Zhejiang University, China, and Baile Zhang at Nanyang Technological University, Singapore, has designed a subwavelength-sized structure whose ability to scatter light is greatly enhanced, providing the first experimental demonstration of the so-called superscattering effect [6]. This phenomenon could be harnessed for a variety of applications, from boosting the efficiency of antennas and energy-harvesting devices to improving the resolution of imaging schemes.


Continue reading -> Physics - Viewpoint: A Metamaterial for Superscattering Light

Experimental Observation of Superscattering
Chao Qian, Xiao Lin, Yi Yang, Xiaoyan Xiong, Huaping Wang, Erping Li, Ido Kaminer, Baile Zhang, and Hongsheng Chen
Phys. Rev. Lett. 122, 063901 (2019)
Published February 11, 2019​

 

[JSCh]

China’s first spallation neutron source goes into operation
By Guo Meiping
2018-08-24 11:56 GMT+8

China's first spallation neutron source (SNS) has officially begun operating on Thursday, making the country the fourth in the world to possess such a facility.

The China Spallation Neutron Source, or CSNS, is considered a “super microscope” that can provide the most intense pulsed neutron beams for scientific research.

The equipment can accelerate protons before smashing them into a target to produce neutrons. The neutrons are then sent to numerous instruments that are used by researchers to study materials.

The “super microscope” is ideal for studying the microstructure of materials, said Chen Hesheng, manager of the CSNS project.

Chen added that the CSNS can be used for researching residual stress of large metal parts, which is vital for improving the performances of key parts of high-speed trains, aircraft engines, and nuclear power plants.

An aerial view of the CSNS. /VCG Photo

The CSNS consists of a powerful linear proton accelerator, a rapid circling synchrotron, a target station and three neutron instruments.

More than 90 percent of the equipment was based on independent research and development and can be domestically produced.

Construction of the CSNS project in China started in 2011 in Dongguan City, south China's Guangdong Province, with a total investment of around 2.3 billion yuan (364 million US dollars).

As one of the largest science and technology infrastructure projects in China, the equipment is expected to have positive effects in promoting the sciences, high-tech development, and national security.

[Top image via VCG]

(With input from Xinhua.)

CSNS Beam Power Reaches 50 kW---Chinese Academy of Sciences
Feb 11, 2019

The China Spallation Neutron Source (CSNS) operated smoothly at a beam power of more than 50kW on Jan. 29, marking another significant milestone for the facility.

The important achievement came less than six months after the facility went into full operation. Based on this breakthrough, scientists are expecting to meet the facility's design goal of 100kW much sooner than originally planned.

Increasing beam power for high-intensity accelerators always requires patience. Based on the experience of other facilities, designers had projected it would take three years after beam commissioning to be able to achieve the beam's design parameters. Therefore, the original plan was to reach the design goal of 100 kW by August 2021, three years after CSNS started full operation.

As the first spallation neutron source in China, CSNS decided to speed up the plan in order to meet users' needs for high neutron flux. The CSNS accelerator team has put much effort into increasing beam power. Each hardware system was stable and reliable during the whole month of January, with the facility's efficiency for user experiments exceeding 93%.

Good beam loss control is one of the key factors in increasing beam power for high-intensity accelerators. After fine-tuning and optimization, uncontrollable beam loss is lower when operating at 50kW than at 20kW, which means uncontrollable beam loss does not increase with increasing beam power.

Measurements of accelerator parts in the tunnel showed that induced radioactivity was much lower than the dose limit required for manual maintenance, thus strongly proving that CSNS's operation is smooth, safe and reliable even at high beam power.

 

[JSCh]

Antenna Protein Structure Reveals the Basis of Efficient Blue-green Light Harvesting and Photoprotection in Diatoms
Jan 31, 2019

Diatoms are abundant photosynthetic organisms in aquatic environments; they contribute 20% of global primary productivity. Their fucoxanthin (Fx) chlorophyll (Chl) a/c-binding proteins (FCPs) have exceptional light harvesting and photoprotection capabilities. However, the structure of the FCP proteins and arrangement of pigments within them remain unknown.

A research team from the Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, solved the crystal structure of an FCP protein from a marine pennate diatom Phaeodactylum tricornutum.

The study, entitled "Structural basis for blue-green light harvesting and energy dissipation in diatoms," is published in Science on February 8, 2019.

The FCP membrane-protein was purified as a homodimer from P. tricornutum and crystallized. The structure was solved by X-ray diffraction at a resolution of 1.8 angstrom, which showed that each FCP monomer contains seven Chls a, two Chls c, seven Fxs, one diadinoxanthin (Ddx), two calcium cations and several lipid molecules.

Compared with light harvesting antennas from higher plants and green algae, the number of Chls is much less, whereas that of Fxs is much larger in the FCP, resulting in a much higher Fx/Chl ratio.

These features, together with the unique arrangement of pigments uncovered, indicates fast energy coupling of Chl c not only with Chl a but also with Fx.

Furthermore, each Fx is surrounded by one or more Chls, providing a basis for efficient energy transfer between them and also efficient dissipation of excess energy under high light conditions.

The binding environment of the two end groups of each Fx showed different hydrophilicities within the protein scaffold, suggesting differences in their preferred absorption region of the blue-green light.

One Ddx molecule was assigned to a position close to the monomer-monomer interface with a weak electron density, suggesting its easy dissociation from the apoprotein and possible involvement in the Ddx-deepoxidation cycle that functions in excess energy dissipation.

"The network of specific pigments demonstrated by the first and high-resolution FCP structure reveals a solid basis for blue-green light harvesting and super photochemical quenching in diatoms," said Prof. SHEN Jianren, a corresponding author of this study.

"This research provides a new model for theoretical simulations of photosynthetic energy trapping and transfer, and may also aid in designing photosynthetic organisms with enhanced light-harvesting and photoprotection capabilities," said SHEN.

The crystals of FCP in an orange-brown color (left upside) and the structure of the FCP protein embedded in the thylakoid membrane of diatoms (middle) (Image by SHEN Jianren)



Antenna Protein Structure Reveals the Basis of Efficient Blue-green Light Harvesting and Photoprotection in Diatoms---Chinese Academy of Sciences

Wenda Wang, Long-Jiang Yu, Caizhe Xu, Takashi Tomizaki, Songhao Zhao, Yasufumi Umena, Xiaobo Chen, Xiaochun Qin, Yueyong Xin, Michihiro Suga, Guangye Han, Tingyun Kuang, Jian-Ren Shen. Structural basis for blue-green light harvesting and energy dissipation in diatoms. Science (2019). DOI: 0.1126/science.aav0365​

 

[055_destroyer]

AI system spots childhood disease like a doctor



PARIS: An artificial intelligence (AI) programme developed in China that combs through test results, health records and even handwritten notes diagnosed childhood diseases as accurately as doctors, researchers said Monday (Feb 12).

From the flu and asthma to life-threatening pneumonia and meningitis, the system consistently matched or out-performed primary care paediatricians, they reported in Nature Medicine.


Dozens of studies in recent months have detailed how AI is revolutionising the detection of diseases including cancers, genetic disorders and Alzheimer's.

AI-based technology learns and improves in a way similar to humans, but has virtually unlimited capacity for data processing and storage.

"I believe that it will be able to perform most of the jobs a doctor does," senior author Kang Zhang, a researcher at the University of California, San Diego, told AFP.

"But AI will never replace a doctor," he added, comparing the relationship to an autonomous car that remains under the supervision of a human driver.


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"It will simply allow doctors to do a better job in less time and at lower costs."

The new technology, said Zhang, is the first in which AI absorbs unstructured data and "natural language" to imitate the process by which a physician figures out what's wrong with a patient.

"It can mimic a human paediatrician to interpret and integrate all types of medical data - patient complaints, medical history, blood and imaging tests - to make a diagnosis," he said.

The system can be easily transferred to other languages and settings, he added.

By comparing hundreds of bits of information about a single patient with a vast store of acquired knowledge, the technology unearths links that previous statistical methods - and sometimes flesh-and-blood doctors - overlook.

IN THE NICK OF TIME

To train the proof-of-concept system, Zhang and a team of 70 scientists injected more than 100 million data points from 1.3 million pediatrics patient visits at a major referral centre in Guangzhou, China.

The AI programme diagnosed respiratory infections and sinusitis - a common sinus infection - with 95 per cent accuracy.

More surprising, Kang said, it did as well with less common diseases: acute asthma (97 per cent), bacterial meningitis and varicella (93 per cent), and mononucleosis (90 per cent).

Such technologies may be coming in just the nick of time.

"The range of diseases, diagnostic testing and options for treatment has increased exponentially in recent years, rendering the decision-making process for physicians more complicated," Nature noted in a press release.

Experts not involved in the research said the study is further proof of AI's expanding role in medicine.

"The work has the potential to improve healthcare by assisting the clinician in making rapid and accurate diagnoses," said Duc Pham, a professor of engineering at the University of Birmingham.

"The results show that, on average, the system performed better than junior doctors."

"But it will not replace clinicians," he added.

Machine learning - which forms general rules from specific training examples - "cannot guarantee 100 per cent correct results, no matter how many training examples they use."

AI-based tools for diagnosis abound, especially for interpreting machine-generated images such as MRI and CAT scans.

A method unveiled last month in the United States to detect lesions that can lead to cervical cancer found pre-cancerous cells with 91 per cent accuracy, compared to 69 per cent for physical exams performed by doctors and 71 per cent for conventional lab tests.

Likewise, a cellphone app based on AI technology out-performed experienced dermatologists in distinguishing potentially cancerous skin lesions from benign ones, according to a study in the Annals of Oncology.


Read more at https://www.channelnewsasia.com/news/health/ai-system-spots-childhood-disease-like-a-doctor-11231904

 

[JSCh]

Researchers create ultra-lightweight ceramic material that can better withstand extreme temperatures
UCLA-led team develops highly durable aerogel that could ultimately be an upgrade for insulation on spacecraft

Matthew Chin | February 14, 2019

Xiangfeng Duan and Xiang Xu/UCLA
The new ceramic aerogel is so lightweight that it can rest on a flower without damaging it.

UCLA researchers and collaborators at eight other research institutions have created an extremely light, very durable ceramic aerogel. The material could be used for applications like insulating spacecraft because it can withstand the intense heat and severe temperature changes that space missions endure.

Ceramic aerogels have been used to insulate industrial equipment since the 1990s, and they have been used to insulate scientific equipment on NASA’s Mars rover missions. But the new version is much more durable after exposure to extreme heat and repeated temperature spikes, and much lighter. Its unique atomic composition and microscopic structure also make it unusually elastic.

When it’s heated, the material contracts rather than expanding like other ceramics do. It also contracts perpendicularly to the direction that it’s compressed — imagine pressing a tennis ball on a table and having the center of the ball move inward rather than expanding out — the opposite of how most materials react when compressed. As a result, the material is far more flexible and less brittle than current state-of-the-art ceramic aerogels: It can be compressed to 5 percent of its original volume and fully recover, while other existing aerogels can be compressed to only about 20 percent and then fully recover.

The research, which was published today in Science, was led by Xiangfeng Duan, a UCLA professor of chemistry and biochemistry; Yu Huang, a UCLA professor of materials science and engineering; and Hui Li of Harbin Institute of Technology, China. The study’s first authors are Xiang Xu, a visiting postdoctoral fellow in chemistry at UCLA from Harbin Institute of Technology; Qiangqiang Zhang of Lanzhou University; and Menglong Hao of UC Berkeley and Southeast University.

Other members of the research team were from UC Berkeley; Purdue University; Lawrence Berkeley National Laboratory; Hunan University, China; Lanzhou University, China; and King Saud University, Saudi Arabia.

Despite the fact that more than 99 percent of their volume is air, aerogels are solid and structurally very strong for their weight. They can be made from many types of materials, including ceramics, carbon or metal oxides. Compared with other insulators, ceramic-based aerogels are superior in blocking extreme temperatures, and they have ultralow density and are highly resistant to fire and corrosion — all qualities that lend themselves well to reusable spacecraft.

But current ceramic aerogels are highly brittle and tend to fracture after repeated exposure to extreme heat and dramatic temperature swings, both of which are common in space travel.

The new material is made of thin layers of boron nitride, a ceramic, with atoms that are connected in hexagon patterns, like chicken wire.

In the UCLA-led research, it withstood conditions that would typically fracture other aerogels. It stood up to hundreds of exposures to sudden and extreme temperature spikes when the engineers raised and lowered the temperature in a testing container between minus 198 degrees Celsius and 900 degrees above zero over just a few seconds. In another test, it lost less than 1 percent of its mechanical strength after being stored for one week at 1,400 degrees Celsius.

“The key to the durability of our new ceramic aerogel is its unique architecture,” Duan said. “Its innate flexibility helps it take the pounding from extreme heat and temperature shocks that would cause other ceramic aerogels to fail.”

Oszie Tarula/UCLA
Breath mint-sized samples of the ceramic aerogels developed by a UCLA-led research team. The material is 99 percent air by volume, making it super lightweight.

Ordinary ceramic materials usually expand when heated and contract when they are cooled. Over time, those repeated temperature changes can lead those materials to fracture and ultimately fail. The new aerogel was designed to be more durable by doing just the opposite — it contracts rather than expanding when heated.

In addition, the aerogel’s ability to contract perpendicularly to the direction that it’s being compressed — like the tennis ball example — help it survive repeated and rapid temperature changes. (That property is known as a negative Poisson’s ratio.) It also has interior “walls” that are reinforced with a double-pane structure, which cuts down the material’s weight while increasing its insulating abilities.

Duan said the process researchers developed to make the new aerogel also could be adapted to make other ultra-lightweight materials.

“Those materials could be useful for thermal insulation in spacecraft, automobiles or other specialized equipment,” he said. “They could also be useful for thermal energy storage, catalysis or filtration.”

The research was partly supported by grants from the National Science Foundation.



Researchers create ultra-lightweight ceramic material that can better withstand extreme temperatures | UCLA

Xiang Xu, Qiangqiang Zhang, Menglong Hao, Yuan Hu, Zhaoyang Lin, Lele Peng, Tao Wang, Xuexin Ren, Chen Wang, Zipeng Zhao, Chengzhang Wan, Huilong Fei, Lei Wang, Jian Zhu, Hongtao Sun, Wenli Chen, Tao Du, Biwei Deng, Gary J. Cheng, Imran Shakir, Chris Dames, Timothy S. Fisher, Xiang Zhang, Hui Li, Yu Huang, Xiangfeng Duan. Double-negative-index ceramic aerogels for thermal superinsulation. Science (2019). DOI: 10.1126/science.aav7304​

 

[JSCh]

Massive 1994 Bolivian earthquake reveals mountains 660 kilometers below our feet
Liz Fuller-Wright, Office of Communications
Feb. 14, 2019 2 p.m.

Most schoolchildren learn that the Earth has three (or four) layers: a crust, mantle and core, which is sometimes subdivided into an inner and outer core. That’s not wrong, but it does leave out several other layers that scientists have identified within the Earth, including the transition zone within the mantle.

Princeton seismologist Jessica Irving worked with then-graduate student Wenbo Wu and another collaborator to determine the roughness at the top and bottom of the transition zone, a layer within the mantle, using scattered earthquake waves. They found that the top of the transition zone, a layer located 410 kilometers down, is mostly smooth, but the base of the transition zone, 660 km down, in some places is much rougher than the global surface average. “In other words, stronger topography than the Rocky Mountains or the Appalachians is present at the 660-km boundary,” said Wu. NOTE: This graphic is not to scale.
Image by Kyle McKernan, Office of Communications

In a study published this week in Science, Princeton geophysicists Jessica Irving and Wenbo Wu, in collaboration with Sidao Ni from the Institute of Geodesy and Geophysics in China, used data from an enormous earthquake in Bolivia to find mountains and other topography on the base of the transition zone, a layer 660 kilometers (410 miles) straight down that separates the upper and lower mantle. (Lacking a formal name for this layer, the researchers simply call it “the 660-km boundary.”)

To peer deep into the Earth, scientists use the most powerful waves on the planet, which are generated by massive earthquakes. “You want a big, deep earthquake to get the whole planet to shake,” said Irving, an assistant professor of geosciences.

Big earthquakes are vastly more powerful than small ones — energy increases 30-fold with every step up the Richter scale — and deep earthquakes, “instead of frittering away their energy in the crust, can get the whole mantle going,” Irving said. She gets her best data from earthquakes that are magnitude 7.0 or higher, she said, as the shockwaves they send out in all directions can travel through the core to the other side of the planet — and back again. For this study, the key data came from waves picked up after a magnitude 8.2 earthquake — the second-largest deep earthquake ever recorded — that shook Bolivia in 1994.

“Earthquakes this big don’t come along very often,” she said. “We’re lucky now that we have so many more seismometers than we did even 20 years ago. Seismology is a different field than it was 20 years ago, between instruments and computational resources.”

Seismologists and data scientists use powerful computers, including Princeton’s Tiger supercomputer cluster, to simulate the complicated behavior of scattering waves in the deep Earth.

The technology depends on a fundamental property of waves: their ability to bend and bounce. Just as light waves can bounce (reflect) off a mirror or bend (refract) when passing through a prism, earthquake waves travel straight through homogenous rocks but reflect or refract when they encounter any boundary or roughness.

“We know that almost all objects have surface roughness and therefore scatter light,” said Wu, the lead author on the new paper, who just completed his geosciences Ph.D. and is now a postdoctoral researcher at the California Institute of Technology. “That’s why we can see these objects — the scattering waves carry the information about the surface’s roughness. In this study, we investigated scattered seismic waves traveling inside the Earth to constrain the roughness of the Earth’s 660-km boundary.”

The researchers were surprised by just how rough that boundary is — rougher than the surface layer that we all live on. “In other words, stronger topography than the Rocky Mountains or the Appalachians is present at the 660-km boundary,” said Wu. Their statistical model didn’t allow for precise height determinations, but there’s a chance that these mountains are bigger than anything on the surface of the Earth. The roughness wasn’t equally distributed, either; just as the crust’s surface has smooth ocean floors and massive mountains, the 660-km boundary has rough areas and smooth patches. The researchers also examined a layer 410 kilometers (255 miles) down, at the top of the mid-mantle “transition zone,” and they did not find similar roughness.

“They find that Earth’s deep layers are just as complicated as what we observe at the surface,” said seismologist Christine Houser, an assistant professor at the Tokyo Institute of Technology who was not involved in this research. “To find 2-mile (1-3 km) elevation changes on a boundary that is over 400 miles (660 km) deep using waves that travel through the entire Earth and back is an inspiring feat. … Their findings suggest that as earthquakes occur and seismic instruments become more sophisticated and expand into new areas, we will continue to detect new small-scale signals which reveal new properties of Earth’s layers.”

Seismologist Jessica Irving, an assistant professor of geosciences, sits with two meteorites from Princeton University’s collection that contain iron thought to come from the interiors of planetesimals. Irving uses seismology to investigate the interior of our own planet, recently finding mountain-sized topographic roughness on the 660-km boundary at the base of the mantle’s transition zone.
Photo by Denise Applewhite, Office of Communications

What it means
The presence of roughness on the 660-km boundary has significant implications for understanding how our planet formed and continues to function. That layer divides the mantle, which makes up about 84 percent of the Earth’s volume, into its upper and lower sections. For years, geoscientists have debated just how important that boundary is. In particular, they have investigated how heat travels through the mantle — whether hot rocks are carried smoothly from the core-mantle boundary (almost 2,000 miles down) all the way up to the top of the mantle, or whether that transfer is interrupted at this layer. Some geochemical and mineralogical evidence suggests that the upper and lower mantle are chemically different, which supports the idea that the two sections don’t mix thermally or physically. Other observations suggest no chemical difference between the upper and lower mantle, leading some to argue for what’s called a “well-mixed mantle,” with both the upper and lower mantle participating in the same heat-transfer cycle.

“Our findings provide insight into this question,” said Wu. Their data suggests that both groups might be partially right. The smoother areas of the 660-km boundary could result from more thorough vertical mixing, while the rougher, mountainous areas may have formed where the upper and lower mantle don’t mix as well.

In addition, the roughness the researchers found, which existed at large, moderate and small scales, could theoretically be caused by heat anomalies or chemical heterogeneities. But because of how heat in transported within the mantle, Wu explained, any small-scale thermal anomaly would be smoothed out within a few million years. That leaves only chemical differences to explain the small-scale roughness they found.

What could cause significant chemical differences? The introduction of rocks that used to belong to the crust, now resting quietly in the mantle. Scientists have long debated the fate of the slabs of sea floor that get pushed into the mantle at subduction zones, the collisions happening found all around the Pacific Ocean and elsewhere around the world. Wu and Irving suggest that remnants of these slabs may now be just above or just below the 660-km boundary.

“It’s easy to assume, given we can only detect seismic waves traveling through the Earth in its current state, that seismologists can’t help understand how Earth’s interior has changed over the past 4.5 billion years,” said Irving. “What’s exciting about these results is that they give us new information to understand the fate of ancient tectonic plates which have descended into the mantle, and where ancient mantle material might still reside.”

She added: “Seismology is most exciting when it lets us better understand our planet’s interior in both space and time.”

“Inferring Earth’s discontinuous chemical layering from the 660-kilometer boundary topography,” by Wenbo Wu, Sidao Ni and Jessica Irving, appears in the Feb. 15 issue of the journal Science. The research was supported by the National Basic Research Program of China (973 Program, grant 2014CB845901), the Chinese Academy of Sciences (grant XDB18000000), the National Natural Science Foundation of China (grant 41590854), and the National Science Foundation (grants EAR1644399 and 1736046).



Massive 1994 Bolivian earthquake reveals mountains 660 kilometers below our feet | Princeton University

Wenbo Wu, Sidao Ni, Jessica C. E. Irving. Inferring Earth’s discontinuous chemical layering from the 660-kilometer boundary topography. Science (2019). DOI: 10.1126/science.aav0822​