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A New Data-Driven Sparse-Learning Approach to Study Chemical Reaction Networks

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arXiv 2017年

作者： Harirchi, Farshad Kim, Doohyun Khalil, Omar Liu, Sijia Elvati, Paolo Hero, Alfred Violi, Angela Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109-2125 United States Department of Mechanical Engineering University of Michigan Ann ArborMI48109-2125 United States Biophysics Program Departments of Chemical Engineering Biomedical Engineering Macromolecular Science and Engineering University of Michigan Ann ArborMI48109-2125 United States

Chemical kinetic mechanisms can be represented by sets of elementary reactions that are easily translated into mathematical terms using physicochemical relationships. The schematic representation of reactions captures the interactions between reacting species and products. Determining the minimal chemical interactions underlying the dynamic behavior of systems is a major task. In this paper, we introduce a novel approach for the identification of the inuential reactions in chemical reaction networks for combustion applications, using a data-driven sparse-learning technique. The proposed approach identifies a set of inuential reactions using species concentrations and reaction rates, with minimal computational cost without requiring additional data or simulations. The new approach is applied to analyze the combustion chemistry of H2andC3H8in a constant-volume homogeneous reactor. The inuential reactions identified by the sparse-learning method are consistent with the current kinetics knowledge of chemical mechanisms. Additionally, we show that a reduced version of the parent mechanism can be generated as a combination of the inuential reactions identified at different times and conditions and that for both H2andC3H8this reduced mechanism performs closely to the parent mechanism as a function of ignition delay over a wide range of conditions. Our results demonstrate the potential of the sparse-learning approach as an effective and efficient tool for mechanism analysis and mechanism reduction. Copyright © 2017, The Authors. All rights reserved.

关键词： Learning systems

Self-Catalyzed Core-Shell GaAs/GaNAs Nanowires Grown on Patterned Si(111)by Gas-Source Molecular Beam Epitaxy

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Self-Catalyzed Core-Shell GaAs/GaNAs Nanowires Grown on Patt...

第十二届全国分子束外延学术会议

作者： Rui La Ren Liu Weichuan Yao Mattias Janssond Shula Chend Janet L.Pan Irina A.Buyanovad S.A.Dayeh Charles W.Tu Graduate Program of Material Science and Engineering University of CaliforniaSan DiegoLa JollaCal Department of Electrical and Computer Engineering University of CaliforniaSan DiegoLa JollaCalifo Department of Physics Chemistry and BiologyLink(o)ping UniversityLink(o)pingSweden 58183 Graduate Program of Material Science and Engineering University of CaliforniaSan DiegoLa JollaCal

Group Ⅲ-Ⅴ semiconductor nanowires(NWs) on Si platform have attracted an increasing interest in recent *** integrating the direct band gap Ⅲ-Ⅴ materials that have high absorption coefficient onto the cost-effective Si platform,it would create novel optoelectronic devices for Si *** advantage of Ⅲ-Ⅴ nanowires grown on Si substrate is that the lattice-match constraint can be relaxed.

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Spin phonon interactions and magneto-thermal transport behavior in p-Si

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arXiv 2017年

作者： Lou, Paul C. de Sousa Oliveira, Laura Tang, Chi Greaney, Alex Kumar, Sandeep Department of Mechanical Engineering University of California RiversideCA United States Department of Physics and Astronomy University of California RiversideCA United States Material Science and Engineering Program University of California RiversideCA United States

The spin-phonon interaction is the dominant process for spin relaxation in Si, and as thermal transport in Si is dominated by phonons, one would expect spin polarization to influence Si's thermal conductivity. Here we report the experimental evidence of just such a coupling. We have performed concurrent measurements of spin, charge, and phonon transport in p-doped Si across a wide range of temperatures. In an experimental system of a free-standing 2 µm p-Si beam coated on one side with a thin (25 nm) ferromagnetic spin injection layer, we use the self-heating 3ω method to measure changes in electrical and thermal conductivity under the influence of a magnetic field. These magneto-thermal transport measurements reveal signatures in the variation of electrical and thermal transport that are consistent with spin-phonon interaction. Raman spectroscopy measurements and first principle's calculations support that these variations are due to spin-phonon interaction. Spin polarization leads to softening of phonon modes, a reduction in the group velocity of acoustic modes, and a subsequent decrease in thermal conductivity at room temperature. Moreover, magneto-thermal transport measurements as a function of temperature indicate a change in the spin-phonon relaxation behavior low temperature. Copyright © 2017, The Authors. All rights reserved.

关键词： Silicon

Spin mediated magneto-electro-thermal transport behavior in Ni80Fe20/MgO/p-Si thin films

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arXiv 2017年

作者： Lou, P.C. Beyermann, W.P. Kumar, S. Department of mechanical engineering University of California RiversideCA United States Department of physics and astronomy University of California RiversideCA United States Material science and engineering program University of California RiversideCA United States

In Si, spin-phonon interaction is the primary spin relaxation mechanism. At low temperatures, the absence of spin-phonon relaxation will lead to enhanced spin accumulation. Spin accumulation may change the electro-thermal transport within the material, and thus may serve as an investigative tool for characterizing spin-mediated behavior. Here we present the first experimental proof of spin accumulation induced electro-thermal transport behavior in a Pd (1 nm)/Ni80Fe20 (25 nm)/MgO (1 nm)/p-Si (2 µm) specimen. The spin accumulation originates from the spin-Hall effect. The spin accumulation changes the phononic thermal transport in p-Si causing the observed magneto-electro-thermal transport behavior. We also observe the inverted switching behavior in magnetoresistance measurement at low temperatures in contrast to magnetic characterization, which is attributed to the canted spin states in p-Si due to spin accumulation. The spin accumulation is elucidated by current dependent anomalous Hall resistance measurement, which shows a decrease as the electric current is increased. This result may open a new paradigm in the field of spin-mediated transport behavior in semiconductor and semiconductor spintronics. Copyright © 2017, The Authors. All rights reserved.

关键词： Spin Hall effect

Corrigendum: Synthesis and characterization of mordenite-type zeolites with varying Si/Al ratio (2019 Mater. Res. Express 6 015515)

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materials Research Express 2018年第3期6卷

作者： Mon Bryan Z Gili Marlon T Conato Material Science and Engineering Program College of Science University of the Philippines Diliman Quezon City Philippines Philippine Nuclear Research Institute—Department of Science and Technology Quezon City Philippines Institute of Chemistry University of the Philippines Diliman Quezon City Philippines

Stability issues in computational screening of carbon nanostructures: illustrations on La endohedrals

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Molecular Simulation 2017年第17期43卷 1472页

作者： Slanina, Zdene k Akasaka, Takeshi Uhlík, Filip Adamowicz, Ludwik Nagase, Shigeru Lu, Xing Life Science Center of Tsukuba Advanced Research Alliance University of Tsukuba Tsukuba Japan . Faculty of Science Department of Physical and Macromolecular Chemistry Charles University Praha Czech Republic . Department of Chemistry and Biochemistry University of Arizona Tucson AZ USA . Fukui Institute for Fundamental Chemistry Kyoto University Kyoto Japan . State Key Laboratory of Materials Processing and Die & Mould Technology School of Material Science and Engineering Huazhong University of Science and Technology Wuhan China .

Three important stability problems frequently met in calculations of carbon nanostructures are outlined. The three relative-stability issues concern: isomeric carbon clusters, non-isomeric metallofullerenes differing in the number of the encapsulated metal atom yet placed in still isomeric carbon cages, and monometallofullerenes with different metals encapsulated in one selected carbon cage. The related computational approaches are illustrated with endohedrals based on La and its congeners located in [Formula omitted.] , [Formula omitted.] and [Formula omitted.] cages, both IPR (isolated-pentagon rule) and non-IPR ones, evaluated using various DFT treatments. It is also concluded that among the La congeners, Ac can produce the second best encapsulation energy, just after La.

关键词： La-based metallofullerenes La@ La@ La2@ La2@ Gibbs-energy stability evaluations stability islands Ac@

Smartphone based colorimetric detection via machine learning

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arXiv 2017年

作者： Mutlu, Ali Y. Kılıç, Volkan Özdemir, Gizem K. Bayram, Abdullah Horzum, Nesrin Solmaz, Mehmet E. Department of Electrical and Electronics Engineering Izmir Katip Celebi University Izmir Turkey Nanoscience and Nanotechnology Program Izmir Katip Celebi University Izmir Turkey Department of Material Science and Engineering Izmir Katip Celebi University Izmir Turkey Department of Engineering Sciences Izmir Katip Celebi University Izmir Turkey

We report the application of machine learning to smartphone based colorimetric detection of pH values. The strip images were used as the training set for Least Squares-Support Vector Machine (LS-SVM) classifier algorithms that were able to successfully classify the distinct pH values. The difference in the obtained image formats was found not to significantly affect the performance of the proposed machine learning approach. Moreover, the influence of the illumination conditions on the perceived color of pH strips was investigated and further experiments were carried out to study effect of color change on the learning model. Test results on JPEG, RAW and RAW-corrected image formats captured in different lighting conditions lead to perfect classification accuracy, sensitivity and specificity, which proves that the colorimetric detection using machine learning based systems is able to adapt to various experimental conditions and is a great candidate for smartphone based sensing in paper-based colorimetric assays. Copyright © 2017, The Authors. All rights reserved.

关键词： Smartphones

Free Surface Relaxations of Star-Shaped Polymer Films

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Physical Review Letters 2017年第22期119卷 227801-227801页

作者： Emmanouil Glynos Kyle J. Johnson Bradley Frieberg Alexandros Chremos Suresh Narayanan Georgios Sakellariou Peter F. Green Institute of Electronic Structure and Laser Foundation for Research and Technology-Hellas P.O. Box 1385 711 10 Heraklion Crete Greece Department of Material Science and Engineering University of Michigan Ann Arbor Michigan 48109 USA Biointeraces Institute University of Michigan Ann Arbor Michigan 48109 USA Macromolecular Science and Engineering University of Michigan Ann Arbor Michigan 48109 USA Materials Science and Engineering Division National Institute of Standards and Technology Gaithersburg Maryland 20899 USA X-ray Science Division Argonne National Laboratory Argonne Illinois 60439 USA Department of Chemistry National and Kapodistrian University of Athens Panepistimiopolis Zografou 15771 Athens Greece National Renewable Energy Laboratory (NREL) Golden Colorado 80401 USA

The surface relaxation dynamics of supported star-shaped polymer thin films are shown to be slower than the bulk, persisting up to temperatures at least 50 K above the bulk glass transition temperature Tgbulk. This be... 详细信息

关键词： Transport phenomena Polymers Thin films

Effect of compaction pressure of green body and heating current on photoluminescence property of ZnO crystal grown by electric current heating method

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IOP Conference Series: materials science and engineering 2018年第1期290卷

作者： A G E Sutjipto M H Mazwir H L Yee S R Misskon A G M Shaitir M A Jusoh R Othman Material Technology Program Faculty of Industrial Sciences & Technology Universiti Malaysia Pahang (UMP) Gambang 26300 Pahang Malaysia Department of Science in Engineering Faculty of Engineering International Islamic University Malaysia (IIUM) Jalan Gombak 53300 Kuala Lumpur Malaysia

In this study, we reported the effect of applied compaction pressure on green body and electric current heating on ceramic bar on the ZnO crystal growth and its photoluminescence characteristic. Crystals grown on ZnO bar sintered by 1100 °C were mostly on (1 0 1) orientation. Sample with 3.0 ton and 3.0 A for applied pressure and current, respectively revealed the shortest photoluminescence (PL) wavelength of 409.5 nm with highest emission energy of 3.03 eV.

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