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突出重点 积极履职 努力服务园区经济社会建设

2019-10-22 23:55 来源:中原网

  突出重点 积极履职 努力服务园区经济社会建设

  同时,支持科技和文化类创新企业、科研院所、新型研发机构、科研类社团组织和科研服务机构等主体引进使用优秀杰出海外人才,聘用千人计划外国专家的,最高可给予其工资薪金80%的资助;聘用海聚工程外国专家的,最高可给予其工资薪金50%的资助。潘建伟介绍,量子卓越中心牵头承担了中科院战略性先导科技专项(A类)量子科学实验卫星、中科院战略性先导科技专项(B类)量子系统的相干控制、发改委量子保密通信京沪干线技术验证及应用示范项目等多项国家重大科技任务,均在顺利实施。

国产创新药的底气:除了仿制药研发,医工总院还形成了完整的创新药物研发链。今年59岁的深圳市政协原副主席黄志光,此前一审被广州市中院认定受贿钱物300万余元并非法持有枪支被判刑14年。

  2015年,她又出资与外地客商共同建设了东方蓝毛绒玩具加工厂,这个劳动密集型企业一下子让80多名群众,实现了家门口就业。国产创新药的底气:除了仿制药研发,医工总院还形成了完整的创新药物研发链。

  所以老年人一定要注意身体保健,可有助于延缓听力损失的发展,注重营养合理搭配,多吃蔬菜、水果,少吃高胆固醇脂肪饮食,远离噪声,避免过度疲劳,忌烟酒,经常锻炼身体,预防老年性疾病。于是,有朋友问:限购放松或取消的城市,值得不值得去投资?我的建议是,即使大批城市取消限购,即使你能够在限购城市买到房,如果不是价格特别低,捡到大便宜,或者周边是特别稀缺的资源,投资就算了吧。

到目前为止,FT账户开设已有7万个,累计融资总额超过万亿元人民币。

  应勇表示,FT账户是自贸区金融改革的一大创新。

  1保护孩子听力从0岁开始我国先天性听力障碍发病率为1‰-3‰,7岁以下聋儿大约有80万,并且每年还在以3万人的速度递增。王志国介绍,酷开作为一家聚焦智能电视大屏价值挖掘的技术平台,经过多年培育,自有终端数量已经突破2800万,成为中国最大智能电视OTT平台。

  在人才评价上,北京将注重成果评价,中国专利金奖获奖专利的发明人、获得3项以上(含)发明专利的独立完成人、以第二作者及以上身份获得6项以上(含)发明专利的主要完成人,其专利取得显著经济社会效益的可申请办理人才引进。

  这个过程值得期待,但不可能一蹴而就。根据国家统计局北京调查总队昨天发布的2018年2月份北京房价数据显示,上个月北京新建住宅价格比1月份全面下滑,其中144平方米以上大户型价格跌幅最大,达到%;其次是90至144平方米的中户型价格环比下滑了%,90平方米以上小户型相对保值,但也下滑了%。

  其中前世界银行集团高级数据科学家、美国乔治梅森大学哥伦比亚大学客座授徐来表示大数据和人工智能的结合相辅相成也是必然的趋势。

  我觉得Keep是时候,有机会、有决心、也有义务站出来,努力去尽所能创造一个科技互联的运动生态。

  近日,中国医药工业研究总院(下称医工总院)院长魏宝康在接受《中国经济周刊》专访时说。这款智能跑步机采用极简设计风格,拥有超薄机身的同时,搭载强劲硬件配置,实现家用体积、商用体验,创新的而且旋钮设计,也革新了传统跑步机的操作方式。

  

  突出重点 积极履职 努力服务园区经济社会建设

 
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突出重点 积极履职 努力服务园区经济社会建设

Release time:September 30, 2019

易事特相关负责人表示,在国家宏观政策指引下,易事特将发挥在光伏发电领域的技术和产品优势,一如既往积极参与全国各地光伏扶贫项目建设,为国家扶贫事业贡献力量。

On September 27, Professor Zhao Lidong’s group in the School of Materials Science and Engineering, Beihang University, published an article entitled “High thermoelectric performance in low-cost SnS0.91Se0.09 crystals” in Science. The research reports the temperature-dependent interplay of several separate electronic bands in hole-doped tin sulfide (SnS) crystals and boosts the synergistic optimization between effective mass (m*) and carrier mobility (μ) by introducing selenium (Se), which enhances the thermoelectric performance of SnS crystals featuring low-cost, Earth-abundan, and environmentally friendly (Science 365 (2019) 1418-1424).

The first author: He Wenke (a PhD student enrolled in 2018)

Supervisor and corresponding author: Zhao Lidong

The first Institute: The School of Materials Science and Engineering, Beihang University

Thermoelectric technology takes advantage of Seebeck Effect (an electromotive force by a temperature gradient) and Peltier Effect (the presence of heating or cooling at an electrified junction of two different conductors) to boost the conversion between thermal energy and electricity. It is a competitive technology, for its system are small in size, free from mechanical wear with no moving parts, noiseless and non-polluting. It provides an environmentally friendly route for power generation through harvesting waste heat, as well as for refrigeration by solid-state coolingand is geared specifically for deep-space exploration.

As an important parameter to measure the properties of thermoelectric materials, the thermoelectric conversion efficiency is determined by the dimensionless figure of merit (ZT) for a given thermoelectric material, expressed by ZT= S2σT/(κlat+κele), where S is the Seebeck coefficient, σ is the electrical conductivity, T is the temperature (in kelvin), and κlat and κele are the phonon and carrier contributions to the thermal conductivity, respectively.

Thus, a high-performance thermoelectric material should have high thermoelectromotive force (to keep high thermoelectric voltage), high electrical conductivity (to reduce Joule losses) and low thermal conductivity (to maintain a steep temperature gradient).

However, these thermoelectric parameters are intertwined, making manipulation of any single parameter targeted to improving the overall thermoelectric performance a challenge. Several strategies have emerged for improving ZTs in recent years. For example, reducing thermal conductivity by introducing nanostructures or all-scale hierarchical architectures, optimizing power factors (PF = S2σ) through band convergence, band flattening, or density of states (DOS) distortion, decoupling thermoelectric parametersthrough embedding magnetic nanoparticles, developing new materials with intrinsically low thermal conductivity or seeking high-performance thermoelectrics through reliable high-throughput material screening.

In 2014, SnSe was discovered to be a type of thermoelectrics with strong anharmonicity (Nature 508 (2014) 373-377). And then, features like multiple valence bands (Science 351 (2016) 141-144) and three-dimensional (3D) charge and 2D phonon transport (Science 360 (2018) 778-783) were found in SnSe.

In the meanwhile, Prof. Zhao’s group has worked towards developing low-cost, environmental friendly and Earth-abundant thermoelectrics. Compared with other IV–VI thermoelectric materials (such as PbTe, PbSe, PbS, SnTe, SnSe, with the abundance of Te in the Earth being 0.001 parts per million (ppm), Se 0.05ppm and S 420ppm), SnS is far superior when considering toxicity and elemental abundance. However, the enhancement of the electrical conductivity and thermoelectric force of SnS remains to be a challenging task.

Featuring high electronegativity and wide band gap, sulfides are not commonly regarded as good conductors of electricity. After two years’ research, the group finds a novel approach to synthesize the polycrystalline SnS (J. Mater. Chem. A, 2 (2014) 17302-17306) whose carrier mobility is 10-15 times higher than normal polycrystalline by regulating anisotropic crystal growth (J. Mater. Chem. A, 6 (2018) 10048-10056), which successfully improves the electrical conductivity of SnS.

Thermoelectric materials demand not only good electrical conductivity, but also asteep temperature gradient. However, it is controversial as the two factors are conditioned by carrier concentration in an anti-correlated way. Therefore, a main task of the research is to optimize a dimensionless quality factor (β) for a given thermoelectric material, characterized by β ∝ (m*)3/2μ, where m* and μ are the effective mass and carrier mobility (they are also anti-correlated), respectively.

In their experiment, first, atomic positions under different temperatures are derived from variable-temperature synchrotron radiation x-ray diffraction data. On the basis of density function theory (DFT) calculated band structure, it is investigated that there is a temperature-dependent evolution and interplay of multiple valence bands in SnS, involving two-band convergence, two-band crossing and two-band divergence. The study also found that the interplay of multiple valence bands can be promoted by introducing Se in SnS (See Fig. 1).

Fig. 1 Through the manipulation of the electronic band structure (Se alloying) , valence bands are sharpened and electrical transport properties are improved with more valence bands involved in electrical transport

Besides, it is found that the introduction of Se can also sharpen the multiple valence bands (which reduces effective mass and increases carrier mobility) and activate more bands (the fourth valence band) to be involved in the electrical transport (which maintains a large effective mass).

The Se alloying, which enhances carrier mobility and contributes to a large effective mass and therefore results in an optimized quality factor β, allows SnS crystal to exhibit high electrical conductivity over the entire working temperature range, even higher than that of the SnSe crystal with multiple valence bands in it (Science 351 (2016) 141-144). Moreover, the maximum figure of merit ZT has increased from ~1.0 to ~1.6 and the average ZT of the entire working temperature has reached ~1.25 after introducing Se.

Compare with other IV-VI compound, SnS is more superior as it is environmental-friendly, highly-efficient, cost effective and can be commercially applied inthermoelectrics in the future.

The work is a joint effort of 27 collaborators from 11 institutes including the research group led by Prof. Li Jingfeng from Tsinghua University, Prof. He Jiaqing’s group from Southern University of Science and Technology, Prof. Stephen J. Pennycook’s group from National University of Singapore, Prof. Michihiro Ohta’s group from the National Institute of Advanced Industrial Science and Technology (Sangyō Gijutsu Sōgō Kenkyū-sho), Hao Lijie and Niu Changlei from China Institute of Atomic Energy, Song Jianming from China Academy Of Engineering Physics, Xu Wei from the Institute of High Energy Physics of the Chinese Academy of Sciences and Prof. Wang Guangtao from Henan Normal University.

Various advanced tests and measuring methods are involved in the research, such as synchrotron radiation x-ray diffraction (SR-XRD), density function theory (DFT) calculations, angle-resolved photoemission spectroscopy (ARPES), x-ray absorption fine structure spectroscopy (XAFS), inelastic neutron scattering (INS) experiment, scanning transmission electron microscopy (STEM), stability test on thermoelectric properties after neutron radiation and thermoelectric conversion efficiency test.

The project is supported by the National Natural Science Foundation of China (51788104), National Key R&D Program of China (2018YFA0702100, 2018YFB0703600), National Natural Science Foundation of China (51772012, 51632005, 51571007), Beijing Natural Science Foundation (JQ18004) and Program of Introducing Talents of Discipline to Universities, or 111 Plan (B17002), etc.

The article is available at:

http://science.sciencemag.org.dqdsrf23.cn/content/365/6460/1418

The link to the website of Prof Zhao’s research group:

http://shi.buaa.edu.cn.dqdsrf23.cn/zhaolidong/zh_CN/index.htm



Edited by Jia Aiping and Xiong Ting

Reviewed by Tan Hualin

Translated by Xiong Ting