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Inside Front Cover: Volume 2 Issue 2

SmartMat 2021年第2期2卷

作者： Jie Xu Xiaoya Cui Nan Liu Yanan Chen Hong-Wei Wang Ministry of Education Key Laboratory of Protein Sciences Beijing Advanced Innovation Center for Structural Biology School of Life Sciences Tsinghua University Beijing China Tsinghua-Peking Joint Center for Life Sciences Tsinghua University Beijing China School of Materials Science and Engineering Tsinghua University Tianjin China Hong-Wei Wang Ministry of Education Key Laboratory of Protein Sciences Beijing Advanced Innovation Center for Structural Biology School of Life Sciences Tsinghua University 100084 Beijing China. Joint Graduate Program of Peking-Tsinghua-NIBS School of Life Sciences Tsinghua University Beijing China Beijing Frontier Research Center for Biological Structures Tsinghua University Beijing China

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Formation of Swiss-cheese Nanostructure of α-Fe2O3 by Reduction

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Microscopy and Microanalysis 2017年第S1期23卷 952-953页

作者： Wenhui Zhu Jonathan P. Winterstein Renu Sharma Guangwen Zhou Department of Mechanical Engineering & Materials Science and Engineering Program State University of New York Binghamton NY USA Center for Nanoscale Science and Technology National Institute of Standards and Technology Gaithersburg MD USA

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The anatomic determinants of conductive hearing loss secondary to tympanic membrane perforation

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Journal of Otology 2017年第3期12卷 125-131页

作者： David J.Carpenter Debara L.Tucci David M.Kaylie Dennis O.Frank-Ito Division of Head and Neck Surgery & Communication Sciences Department of Surgery Duke University Medical Center Durham NC USA Computational Biology & Bioinformatics PhD Program Duke University Durham NC USA Department of Mechanical Engineering and Materials Science Duke University Durham NC USA

Objectives: Recent studies have introduced middle ear volume(MEV) as a novel determinant of perforation-induced conductive hearing loss(CHL) in a mechanism driven by trans-tympanic membrane pressure differences. The primary aims of this preliminary report are to: 1) correlate CHL with perforation size; 2) describe the relationship between CHL and MEV; and 3) compare CHL across a range of cholesteatoma ***: A retrospective pilot study was performed in 31 subjects with audiometry indicative of conductive hearing loss, temporal bone CT scans,and no prior middle ear surgery. Perforation size and MEV were analyzed with respect to CHL in a cohort of 10 perforated ears with no cholesteatoma. CHLs were compared in 3 groups defined by extent of cholesteatoma ***: Ears with large and small perforations showed mean ABG values of 32.0 ± 15.7 dB and 16.0 ± 16.4 dB, respectively. A direct relationship was observed between MEV and CHL for ears with large perforations across all frequencies, whereas this relationship for small perforations was frequency-dependent. Finally, a statistically significant increase in CHL was found across ears with increasing cholesteatoma involvement at 1000 Hz(X^2(2) = 9.786, p = 0.008),2000 Hz(x^2(2) = 8.455, p = 0.015),and 4000 Hz(x^2(2)= 8.253, p = 0.016).Conclusions: These pilot data suggest that greater perforation-induced conductive hearing losses may be associated with larger perforation sizes and cholesteatoma. The correlation between MEV and CHL may require additional study.

关键词： Perforation-induced hearing loss Conductive hearing loss Middle ear volume Three-dimensional volume reconstruction

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Sensitive mechanochromisms based on a polymer bilayer structure 75

Sensitive mechanochromisms based on a polymer bilayer struct...

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75th Annual Technical Conference and Exhibition of the Society of Plastics Engineers, SPE ANTEC Anaheim 2017

作者： Zeng, Songshan Zhang, Dianyun Huang, Wenhan Wang, Zhaofeng Freire, Stephan G. Smith, Andrew T. Huang, Emily Y. Nguon, Helen Yu, Xiaoyuan Sun, Luyi Department of Chemical and Biomolecular Engineering Polymer Program Institute of Materials Science University of Connecticut StorrsCT06269 United States Department of Mechanical Engineering University of Connecticut StorrsCT06269 United States School of Mechanical and Electrical Engineering Heyuan Polytechnic Heyuan Guangdong517000 China Institute of Biomaterial College of Materials and Energy South China Agricultural University Guangzhou Guangdong510642 China

ISBN: (纸本)9780692883099

We have designed a series of mechanochromic devices inspired by nature with the capabilities of changing transparency and "switching on/off" luminescence in response to mechanical stimuli. The key to accomplish these excellent optical properties is to control strain-induced surface engineering, that is, the longitudinal cracks opening and transverse invaginated folds. All of these devices are comprised of a rigid thin layer atop polydimethylsiloxane (PDMS) based elastomer, which can be facilely and quickly fabricated. For transparency change mechanochromism, the folds and cracks with excellent light trapping and scattering capabilities can endow high opaqueness to the originally highly transparent samples. The evolution of crack opening and fold-ridge mechanisms are captured through finite analysis that incorporates damage and cracks in the rigid thin layer. For luminescent mechanochromism, the strain-tunable cracks on the UV shield layer act as "gates" to mediate the traveling of UV light to "switch on/off" the luminescence of mechanochromism. This device exhibits a remarkably high strain responsive sensitivity, demonstrating an excellent sensing capability for detecting mechanical failure or damage. All the mechanochromisms also show outstanding durability and reversibility.

关键词： Luminescence

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Change of Fermi surface states related with two different Tc-raising mechanisms in iron pnictide superconductors

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Physical Review B 2018年第10期98卷 100501(R)-100501(R)页

作者： A. Takemori T. Hajiri S. Miyasaka Z. H. Tin T. Adachi S. Ideta K. Tanaka M. Matsunami S. Tajima Department of Physics Osaka University Osaka 560-0043 Japan Department of Materials Physics Graduate School of Engineering Nagoya University Nagoya 464-8603 Japan UVSOR Facility Institute for Molecular Science Okazaki 444-8585 Japan School of Physical Sciences The Graduate University for Advanced Studies (SOKENDAI) Okazaki 444-8585 Japan

The evolution of Fermi surface (FS) states of NdFeAs1−xPxO0.9F0.1 single crystals with As/P substitution has been investigated. The critical temperature Tc and the power-law exponent (n) of temperature-dependent resistivity [ρ(T)=ρ0+ATn] show a clear correlation above x=0.2, suggesting that Tc is enhanced with increasing bosonic fluctuations in the same type of FS state. Around x=0.2, all the transport properties show anomalies, indicating that x∼0.2 is the critical composition of a drastic FS change. Angle-resolved photoemission spectroscopy has more directly revealed the distinct change of FS around x=0.2, that one hole FS disappears at the Brillouin zone center and the other FS with a propellerlike shape appears at the zone corner with decreasing x. These results are indicative of the existence of two types of FS states with different nesting conditions that are related with two Tc-raising mechanisms in this system.

关键词： Superconductivity Iron-based superconductors Photoemission spectroscopy Transport techniques

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Efficient Construction Method for Phase Diagrams Using Uncertainty Sampling

arXiv

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arXiv 2018年

作者： Terayama, Kei Tamura, Ryo Nose, Yoshitaro Hiramatsu, Hidenori Hosono, Hideo Okuno, Yasushi Tsuda, Koji RIKEN Center for Advanced Intelligence Project Tokyo103-0027 Japan Medical Sciences Innovation Hub Program RIKEN Cluster for Science Technology and Innovation Hub Kanagawa230-0045 Japan Graduate school of Medicine Kyoto University Kyoto606-8507 Japan National Institute for Materials Science Ibaraki305-0044 Japan Research and Services Division of Materials Data and Integrated System National Institute for Materials Science Ibaraki305-0047 Japan Graduate school of Frontier Sciences University of Tokyo Chiba277-8568 Japan Department of Materials Science and Engineering Kyoto University Kyoto606-8501 Japan Laboratory for Materials and Structures Institute of Innovative Research Tokyo Institute of Technology Yokohama226-8503 Japan Materials Research Center for Element Strategy Tokyo Institute of Technology Yokohama226-8503 Japan

We develop a method to efficiently construct phase diagrams using machine learning. Uncertainty sampling (US) in active learning is utilized to intensively sample around phase boundaries. Here, we demonstrate constructions of three known experimental phase diagrams by the US approach. Compared with random sampling, the US approach decreases the number of sampling points to about 20%. In particular, the reduction rate is pronounced in more complicated phase diagrams. Furthermore, we show that using the US approach, undetected new phase can be rapidly found, and smaller number of initial sampling points are sufficient. Thus, we conclude that the US approach is useful to construct complicated phase diagrams from scratch and will be an essential tool in materials science. Copyright © 2018, The Authors. All rights reserved.

关键词： Graphic methods

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Transformation of monolayer MoS2 into multiphasic MoTe2： Chalcogen atom-exchange synthesis route

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Nano Research 2017年第8期10卷 2761-2771页

作者： Qiyi Fang Zhepeng Zhang Qingqing Ji Siya Zhu Yue Gong Yu Zhang Jianping Shi Xiebo Zhou Lin Gu Qian Wang Yanfeng Zhang Department of Materials Science and Engineering College of Engineering Peking University Beijing 100871 China Center for Nanochemistry (CNC) Beijing National Laboratory for Molecular Sciences College of Chemistry and Molecular Engineering Academy for Advanced lnterdisciplinary Studies Peking University Beijing 100871 China Center for Applied Physics and Technology Peking University Beijing 100871 China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China Collaborative Innovation Center of Quantum Matter Beijing 100190 China School of Physical Sciences University of Chinese Academy of Sciences Beijing 100190 China

Molybdenum ditelluride （MoTe2）, which is an important transition-metal dichalcogenide, has attracted considerable interest owing to its unique properties, such as its small bandgap and large Seebeck coefficient. However, the batch production of monolayer MoTe2 has been rarely reported. In this study, we demonstrate the synthesis of large-domain （edge length exceeding 30 μm）, monolayer MoTe2 from chemical vapor deposition-grown monolayer MoS2 using a chalcogen atom-exchange synthesis route. An in-depth investigation of the tellurization process reveals that the substitution of S atoms by Te is prevalently initiated at the edges and grain boundaries of the monolayer MoS2, which differs from the homogeneous selenization of MoS2 flakes with the formation of alloyed Mo-S-Se hybrids. Moreover, we detect a large compressive strain （approximately -10%） in the transformed MoTe2 lattice, which possibly drives the phase transition from 2H to 1T＇ at the reaction temperature of 500 ℃. This phase change is substantiated by experimental facts and first-principles calculations. This work introduces a novel route for the templated synthesis of two-dimensional layered materials through atom substitutional chemistry and provides a new pathway for engineering the strain and thus the intriguing physics and chemistry.

关键词： transition-metal dichacogenide MoTe2 atom exchange multiphase phase transformation

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ZnO-CuO core-shell heterostructure for improving the efficiency of ZnO-based dye-sensitized solar cells

ZnO-CuO core-shell heterostructure for improving the efficie...

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MRS Advances

作者： Jung, Kichang Lim, Taehoon Li, Yaqiong Martinez-Morales, Alfredo A. Department of Chemical and Environmental Engineering University of California RiversideCA92507 United States Materials Science and Engineering Program University of California RiversideCA92507 United States Southern California Research Initiative for Solar Energy University of California RiversideCA92507 United States

In this work, the integration of ZnO-CuO core-shell nanostructures shows improvement in the conversion efficiency of ZnO-based dye-sensitized solar cells (DSSCs). This is due to CuO acting as a secondary absorption layer that allows the absorption of near-infrared (NIR) light increasing the generated photocurrent in the device, and as a blocking layer that reduces electron-hole recombination. The ZnO core and encapsulating CuO shell are synthesized through chemical vapor deposition (CVD), and thermal oxidation of a Cu seed layer, respectively. The crystallinity of the synthesized ZnO and CuO is analyzed by X-ray diffraction (XRD). Scanning electron microscope (SEM) images show the change in morphology through the steps of Cu seed layer deposition and thermal oxidation of this layer. To determine optical properties of CuO on ZnO nanorods, UV-Vis-NIR photospectrocopy is used. The comparison of conversion efficiency of DSSCs using two different photoelectrodes (i.e. ZnO nanorods versus ZnO-CuO core-shell nanostructure) is performed by I-V measurements. Copyright © materials Research Society 2017.

关键词： Copper oxides

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Morphology and mechanical properties of nanocrystalline Cu/Ag Alloy

arXiv

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arXiv 2017年

作者： Li, Ao Szlufarska, Izabela Materials Science Program University of Wisconsin MadisonWI United States Department of Materials Science and Engineering University of Wisconsin MadisonWI United States

Hybrid Monte Carlo (MC)/molecular dynamics (MD) simulations are conducted to study the microstructures of nanocrystalline (nc) Cu/Ag alloys with various Ag concentrations. When the Ag concentration is below 50 Ag atoms/nm2, an increase in Ag concentration leads to a gradual growth of monolayer grain boundary (GB) complexions into nanolayer complexions. Above the concentration of 50 Ag atoms/nm2, wetting layers with a bulk crystalline phase are observed. The effects of Ag on mechanical properties and deformation mechanisms of nc Cu/Ag alloys are investigated in MD simulations of uniaxial tension. GB sliding resistance is found to first increase and then decrease with an increase in Ag concentration. Surprisingly, we also find that the dislocation density decreases monotonically with an increase in Ag concentration, which suggests that the grain interiors are softened by the introduction of Ag dopants at GBs. In addition, there is a critical Ag concentration that maximizes flow stress of nc Cu/Ag alloys. The flow stress, GB sliding resistance, and the intragranular dislocation densities become less sensitive to Ag dopants when the grain diameter increases from 5nm to 40nm. Copyright © 2017, The Authors. All rights reserved.

关键词： Nanocrystals

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Devulcanization of natural rubber in composites with distinct crosslink densities by twin-screw extruder

Devulcanization of natural rubber in composites with distinc...

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作者： Barbosa, Rafael Nunes, Anderson Thadeu Ambrósio, José Donato Materials Science and Engineering Postgraduate Program - PPGCEM Federal University of São Carlos - UFSCar São Carlos SP Brazil Center of Characterization and Materials Development - CCDM Federal University of São Carlos - UFSCar São Carlos SP Brazil

In this study, the effects of the devulcanization process realized by an intermeshing co-rotating twin-screw extruder (ICTSE) on three vulcanized Natural Rubber (NR) composites with different crosslink densities (CD) have been investigated. The extrusion parameters were fixed, as well as the initial material granulometry and auxiliary thermoplastic added to the process. After composites vulcanization, they were characterized accordingly their soluble fraction (SF), crosslink density (CD), mechanical properties and thermogravimetry (TGA). The extrusion was performed on the vulcanized elastomers pursuing selectively crosslink rupture and the same characterization previously cited was conducted on the devulcanized material, except the mechanical properties analysis. The extrusion demonstrate effective devulcanization, evidenced in the increasing of soluble fractions, reduction in crosslink density and thermal stability gain. These results are directly affected by preliminary differences on materials structure and presence of ethylene vinyl-acetate (EVA) on extrusion. © 2017 Universidade Federal de Sao Carlos. All rights reserved.

关键词： Rubber

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