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  • 1
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    Ultrahard nanotwinned cubic boron nitride (2013)
    Nature Publishing Group (NPG)
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    Publication Date: 2013-01-18
    Description: Cubic boron nitride (cBN) is a well known superhard material that has a wide range of industrial applications. Nanostructuring of cBN is an effective way to improve its hardness by virtue of the Hall-Petch effect--the tendency for hardness to increase with decreasing grain size. Polycrystalline cBN materials are often synthesized by using the martensitic transformation of a graphite-like BN precursor, in which high pressures and temperatures lead to puckering of the BN layers. Such approaches have led to synthetic polycrystalline cBN having grain sizes as small as approximately 14 nm (refs 1, 2, 4, 5). Here we report the formation of cBN with a nanostructure dominated by fine twin domains of average thickness approximately 3.8 nm. This nanotwinned cBN was synthesized from specially prepared BN precursor nanoparticles possessing onion-like nested structures with intrinsically puckered BN layers and numerous stacking faults. The resulting nanotwinned cBN bulk samples are optically transparent with a striking combination of physical properties: an extremely high Vickers hardness (exceeding 100 GPa, the optimal hardness of synthetic diamond), a high oxidization temperature ( approximately 1,294 degrees C) and a large fracture toughness (〉12 MPa m(1/2), well beyond the toughness of commercial cemented tungsten carbide, approximately 10 MPa m(1/2)). We show that hardening of cBN is continuous with decreasing twin thickness down to the smallest sizes investigated, contrasting with the expected reverse Hall-Petch effect below a critical grain size or the twin thickness of approximately 10-15 nm found in metals and alloys.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tian, Yongjun -- Xu, Bo -- Yu, Dongli -- Ma, Yanming -- Wang, Yanbin -- Jiang, Yingbing -- Hu, Wentao -- Tang, Chengchun -- Gao, Yufei -- Luo, Kun -- Zhao, Zhisheng -- Wang, Li-Min -- Wen, Bin -- He, Julong -- Liu, Zhongyuan -- England -- Nature. 2013 Jan 17;493(7432):385-8. doi: 10.1038/nature11728.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23325219" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 2
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    The impacts of climate change on water resources and agriculture in China (2010)
    Nature Publishing Group (NPG)
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    Publication Date: 2010-09-03
    Description: China is the world's most populous country and a major emitter of greenhouse gases. Consequently, much research has focused on China's influence on climate change but somewhat less has been written about the impact of climate change on China. China experienced explosive economic growth in recent decades, but with only 7% of the world's arable land available to feed 22% of the world's population, China's economy may be vulnerable to climate change itself. We find, however, that notwithstanding the clear warming that has occurred in China in recent decades, current understanding does not allow a clear assessment of the impact of anthropogenic climate change on China's water resources and agriculture and therefore China's ability to feed its people. To reach a more definitive conclusion, future work must improve regional climate simulations-especially of precipitation-and develop a better understanding of the managed and unmanaged responses of crops to changes in climate, diseases, pests and atmospheric constituents.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Piao, Shilong -- Ciais, Philippe -- Huang, Yao -- Shen, Zehao -- Peng, Shushi -- Li, Junsheng -- Zhou, Liping -- Liu, Hongyan -- Ma, Yuecun -- Ding, Yihui -- Friedlingstein, Pierre -- Liu, Chunzhen -- Tan, Kun -- Yu, Yongqiang -- Zhang, Tianyi -- Fang, Jingyun -- England -- Nature. 2010 Sep 2;467(7311):43-51. doi: 10.1038/nature09364.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Ecology, College of Urban and Environmental Science, Key Laboratory for Earth Surface Processes of the Ministry of Education, and Center of Climate Research, Peking University, Beijing 100871, China. slpiao@pku.edu.cn〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20811450" target="_blank"〉PubMed〈/a〉
    Keywords: Agriculture ; China ; *Climate Change ; Conservation of Natural Resources ; *Economic Development ; Population Dynamics ; Water
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 3
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    Tian et al. reply (2013)
    Nature Publishing Group (NPG)
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    Publication Date: 2013-10-25
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tian, Yongjun -- Xu, Bo -- Yu, Dongli -- Ma, Yanming -- Wang, Yanbin -- Jiang, Yingbing -- Hu, Wentao -- Tang, Chengchun -- Gao, Yufei -- Luo, Kun -- Zhao, Zhisheng -- Wang, Li-Min -- Wen, Bin -- He, Julong -- Liu, Zhongyuan -- England -- Nature. 2013 Oct 24;502(7472):E2-3. doi: 10.1038/nature12621.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24153312" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
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    Aegilops tauschii draft genome sequence reveals a gene repertoire for wheat adaptation (2013)
    Nature Publishing Group (NPG)
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    Publication Date: 2013-03-29
    Description: About 8,000 years ago in the Fertile Crescent, a spontaneous hybridization of the wild diploid grass Aegilops tauschii (2n = 14; DD) with the cultivated tetraploid wheat Triticum turgidum (2n = 4x = 28; AABB) resulted in hexaploid wheat (T. aestivum; 2n = 6x = 42; AABBDD). Wheat has since become a primary staple crop worldwide as a result of its enhanced adaptability to a wide range of climates and improved grain quality for the production of baker's flour. Here we describe sequencing the Ae. tauschii genome and obtaining a roughly 90-fold depth of short reads from libraries with various insert sizes, to gain a better understanding of this genetically complex plant. The assembled scaffolds represented 83.4% of the genome, of which 65.9% comprised transposable elements. We generated comprehensive RNA-Seq data and used it to identify 43,150 protein-coding genes, of which 30,697 (71.1%) were uniquely anchored to chromosomes with an integrated high-density genetic map. Whole-genome analysis revealed gene family expansion in Ae. tauschii of agronomically relevant gene families that were associated with disease resistance, abiotic stress tolerance and grain quality. This draft genome sequence provides insight into the environmental adaptation of bread wheat and can aid in defining the large and complicated genomes of wheat species.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jia, Jizeng -- Zhao, Shancen -- Kong, Xiuying -- Li, Yingrui -- Zhao, Guangyao -- He, Weiming -- Appels, Rudi -- Pfeifer, Matthias -- Tao, Yong -- Zhang, Xueyong -- Jing, Ruilian -- Zhang, Chi -- Ma, Youzhi -- Gao, Lifeng -- Gao, Chuan -- Spannagl, Manuel -- Mayer, Klaus F X -- Li, Dong -- Pan, Shengkai -- Zheng, Fengya -- Hu, Qun -- Xia, Xianchun -- Li, Jianwen -- Liang, Qinsi -- Chen, Jie -- Wicker, Thomas -- Gou, Caiyun -- Kuang, Hanhui -- He, Genyun -- Luo, Yadan -- Keller, Beat -- Xia, Qiuju -- Lu, Peng -- Wang, Junyi -- Zou, Hongfeng -- Zhang, Rongzhi -- Xu, Junyang -- Gao, Jinlong -- Middleton, Christopher -- Quan, Zhiwu -- Liu, Guangming -- Wang, Jian -- International Wheat Genome Sequencing Consortium -- Yang, Huanming -- Liu, Xu -- He, Zhonghu -- Mao, Long -- Wang, Jun -- England -- Nature. 2013 Apr 4;496(7443):91-5. doi: 10.1038/nature12028. Epub 2013 Mar 24.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23535592" target="_blank"〉PubMed〈/a〉
    Keywords: Adaptation, Physiological/*genetics ; Brachypodium/genetics ; Chromosome Mapping ; Chromosomes, Plant/genetics ; DNA Transposable Elements/genetics ; Disease Resistance/genetics ; Genes, Plant/genetics ; Genome, Plant/*genetics ; Hordeum/genetics ; Molecular Sequence Data ; Plant Diseases ; Poaceae/*genetics ; Polyploidy ; Sequence Analysis, RNA ; Transcription Factors/genetics ; Triticum/*genetics/physiology
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 5
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    Nanotwinned diamond with unprecedented hardness and stability (2014)
    Nature Publishing Group (NPG)
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    Publication Date: 2014-06-13
    Description: Although diamond is the hardest material for cutting tools, poor thermal stability has limited its applications, especially at high temperatures. Simultaneous improvement of the hardness and thermal stability of diamond has long been desirable. According to the Hall-Petch effect, the hardness of diamond can be enhanced by nanostructuring (by means of nanograined and nanotwinned microstructures), as shown in previous studies. However, for well-sintered nanograined diamonds, the grain sizes are technically limited to 10-30 nm (ref. 3), with degraded thermal stability compared with that of natural diamond. Recent success in synthesizing nanotwinned cubic boron nitride (nt-cBN) with a twin thickness down to approximately 3.8 nm makes it feasible to simultaneously achieve smaller nanosize, ultrahardness and superior thermal stability. At present, nanotwinned diamond (nt-diamond) has not been fabricated successfully through direct conversions of various carbon precursors (such as graphite, amorphous carbon, glassy carbon and C60). Here we report the direct synthesis of nt-diamond with an average twin thickness of approximately 5 nm, using a precursor of onion carbon nanoparticles at high pressure and high temperature, and the observation of a new monoclinic crystalline form of diamond coexisting with nt-diamond. The pure synthetic bulk nt-diamond material shows unprecedented hardness and thermal stability, with Vickers hardness up to approximately 200 GPa and an in-air oxidization temperature more than 200 degrees C higher than that of natural diamond. The creation of nanotwinned microstructures offers a general pathway for manufacturing new advanced carbon-based materials with exceptional thermal stability and mechanical properties.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Huang, Quan -- Yu, Dongli -- Xu, Bo -- Hu, Wentao -- Ma, Yanming -- Wang, Yanbin -- Zhao, Zhisheng -- Wen, Bin -- He, Julong -- Liu, Zhongyuan -- Tian, Yongjun -- England -- Nature. 2014 Jun 12;510(7504):250-3. doi: 10.1038/nature13381.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China [2]. ; State Key Laboratory for Superhard Materials, Jilin University, Changchun 130012, China. ; Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60439, USA. ; State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24919919" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
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    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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