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| 3. |
- Ablikim, M., et al.
(author)
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Measurement of the leptonic decay width of J/psi using initial state radiation
- 2016
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In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 761, s. 98-103
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Journal article (peer-reviewed)abstract
- Using a data set of 2.93 fb(-1) taken at a center-of-mass energy of root s = 3.773 GeV with the BESIII detector at the BEPCII collider, we measure the process e(+) e(-) -> J/psi gamma -> mu(+)mu(-)gamma and determine the product of the branching fraction and the electronic width B-mu mu . Gamma(ee) = (333.4 +/- 2.5(stat) +/- 4.4(sys)) eV. Using the earlier-published BESIII result for B-mu mu = (5.973 +/- 0.007(stat) +/- 0.037(sys))%, we derive the J/psi electronic width Gamma(ee) = (5.58 +/- 0.05(stat) +/- 0.08(sys)) keV. (C) 2016 The Author(s). Published by Elsevier B.V.
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| 4. |
- Adib Yaghmaie, Farnaz, et al.
(author)
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Differential graphical games for H-infinity control of linear heterogeneous multiagent systems
- 2019
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In: International Journal of Robust and Nonlinear Control. - : WILEY. - 1049-8923 .- 1099-1239. ; 29:10, s. 2995-3013
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Journal article (peer-reviewed)abstract
- Differential graphical games have been introduced in the literature to solve state synchronization problem for linear homogeneous agents. When the agents are heterogeneous, the previous notion of graphical games cannot be used anymore and a new definition is required. In this paper, we define a novel concept of differential graphical games for linear heterogeneous agents subject to external unmodeled disturbances, which contain the previously introduced graphical game for homogeneous agents as a special case. Using our new formulation, we can solve both the output regulation and H-infinity output regulation problems. Our graphical game framework yields coupled Hamilton-Jacobi-Bellman equations, which are, in general, impossible to solve analytically. Therefore, we propose a new actor-critic algorithm to solve these coupled equations numerically in real time. Moreover, we find an explicit upper bound for the overall L2-gain of the output synchronization error with respect to disturbance. We demonstrate our developments by a simulation example.
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| 5. |
- Bjelic, Sinisa, et al.
(author)
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Exploration of Alternate Catalytic Mechanisms and Optimization Strategies for Retroaldolase Design
- 2014
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In: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836 .- 1089-8638. ; 426:1, s. 256-271
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Journal article (peer-reviewed)abstract
- Designed retroaldolases have utilized a nucleophilic lysine to promote carbon-carbon bond cleavage of β-hydroxy-ketones via a covalent Schiff base intermediate. Previous computational designs have incorporated a water molecule to facilitate formation and breakdown of the carbinolamine intermediate to give the Schiff base and to function as a general acid/base. Here we investigate an alternative active-site design in which the catalytic water molecule was replaced by the side chain of a glutamic acid. Five out of seven designs expressed solubly and exhibited catalytic efficiencies similar to previously designed retroaldolases for the conversion of 4-hydroxy-4-(6-methoxy-2-naphthyl)-2-butanone to 6-methoxy-2-naphthaldehyde and acetone. After one round of site-directed saturation mutagenesis, improved variants of the two best designs, RA114 and RA117, exhibited among the highest kcat (>10(-3)s(-1)) and kcat/KM (11-25M(-1)s(-1)) values observed for retroaldolase designs prior to comprehensive directed evolution. In both cases, the >10(5)-fold rate accelerations that were achieved are within 1-3 orders of magnitude of the rate enhancements reported for the best catalysts for related reactions, including catalytic antibodies (kcat/kuncat=10(6) to 10(8)) and an extensively evolved computational design (kcat/kuncat>10(7)). The catalytic sites, revealed by X-ray structures of optimized versions of the two active designs, are in close agreement with the design models except for the catalytic lysine in RA114. We further improved the variants by computational remodeling of the loops and yeast display selection for reactivity of the catalytic lysine with a diketone probe, obtaining an additional order of magnitude enhancement in activity with both approaches.
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| 6. |
- Chang, Guoqing, et al.
(author)
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Topological quantum properties of chiral crystals
- 2018
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In: Nature Materials. - : NATURE PUBLISHING GROUP. - 1476-1122 .- 1476-4660. ; 17:11, s. 978-
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Journal article (peer-reviewed)abstract
- Chiral crystals are materials with a lattice structure that has a well-defined handedness due to the lack of inversion, mirror or other roto-inversion symmetries. Although it has been shown that the presence of crystalline symmetries can protect topological band crossings, the topological electronic properties of chiral crystals remain largely uncharacterized. Here we show that Kramers-Weyl fermions are a universal topological electronic property of all non-magnetic chiral crystals with spin-orbit coupling and are guaranteed by structural chirality, lattice translation and time-reversal symmetry. Unlike conventional Weyl fermions, they appear at time-reversal-invariant momenta. We identify representative chiral materials in 33 of the 65 chiral space groups in which Kramers-Weyl fermions are relevant to the low-energy physics. We determine that all point-like nodal degeneracies in non-magnetic chiral crystals with relevant spin-orbit coupling carry non-trivial Chern numbers. Kramers-Weyl materials can exhibit a monopole-like electron spin texture and topologically non-trivial bulk Fermi surfaces over an unusually large energy window.
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| 7. |
- Chang, Guoqing, et al.
(author)
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Unconventional Chiral Fermions and Large Topological Fermi Arcs in RhSi
- 2017
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In: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 119:20
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Journal article (peer-reviewed)abstract
- The theoretical proposal of chiral fermions in topological semimetals has led to a significant effort towards their experimental realization. In particular, the Fermi surfaces of chiral semimetals carry quantized Chern numbers, making them an attractive platform for the observation of exotic transport and optical phenomena. While the simplest example of a chiral fermion in condensed matter is a conventional vertical bar C vertical bar = 1 Weyl fermion, recent theoretical works have proposed a number of unconventional chiral fermions beyond the standard model which are protected by unique combinations of topology and crystalline symmetries. However, materials candidates for experimentally probing the transport and response signatures of these unconventional fermions have thus far remained elusive. In this Letter, we propose the RhSi family in space group No. 198 as the ideal platform for the experimental examination of unconventional chiral fermions. We find that RhSi is a filling-enforced semimetal that features near its Fermi surface a chiral double sixfold-degenerate spin-1 Weyl node at R and a previously uncharacterized fourfold-degenerate chiral fermion at Gamma. Each unconventional fermion displays Chern number +/- 4 at the Fermi level. We also show that RhSi displays the largest possible momentum separation of compensative chiral fermions, the largest proposed topologically nontrivial energy window, and the longest possible Fermi arcs on its surface. We conclude by proposing signatures of an exotic bulk photogalvanic response in RhSi.
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| 8. |
- Chen, Shuang, et al.
(author)
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Quantitative measurement of hydroxyl radical (OH) concentration in premixed flat flame by combining laser-induced fluorescence and direct absorption spectroscopy
- 2016
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In: Chinese Physics C. - : IOP Publishing. - 1674-1137 .- 1674-1056. ; 25:10
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Journal article (peer-reviewed)abstract
- An accurate and reasonable technique combining direct absorption spectroscopy and laser-induced fluorescence (LIF) methods is developed to quantitatively measure the concentrations of hydroxyl in CH4/air flat laminar flame. In our approach, particular attention is paid to the linear laser-induced fluorescence and absorption processes, and experimental details as well. Through measuring the temperature, LIF signal distribution and integrated absorption, spatially absolute OH concentrations profiles are successfully resolved. These experimental results are then compared with the numerical simulation. It is proved that the good quality of the results implies that this method is suitable for calibrating the OH-PLIF measurement in a practical combustor.
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| 9. |
- Chen, Ziming, et al.
(author)
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Roadmap on perovskite light-emitting diodes
- 2024
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In: JOURNAL OF PHYSICS-PHOTONICS. - : IOP Publishing Ltd. - 2515-7647. ; 6:3
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Journal article (peer-reviewed)abstract
- In recent years, the field of metal-halide perovskite emitters has rapidly emerged as a new community in solid-state lighting. Their exceptional optoelectronic properties have contributed to the rapid rise in external quantum efficiencies (EQEs) in perovskite light-emitting diodes (PeLEDs) from <1% (in 2014) to over 30% (in 2023) across a wide range of wavelengths. However, several challenges still hinder their commercialization, including the relatively low EQEs of blue/white devices, limited EQEs in large-area devices, poor device stability, as well as the toxicity of the easily accessible lead components and the solvents used in the synthesis and processing of PeLEDs. This roadmap addresses the current and future challenges in PeLEDs across fundamental and applied research areas, by sharing the community's perspectives. This work will provide the field with practical guidelines to advance PeLED development and facilitate more rapid commercialization.
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| 10. |
- Ekberg, Peter, et al.
(author)
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Fast and accurate metrology of multi-layered ceramic materials by an automated boundary detection algorithm developed for optical coherence tomography data
- 2014
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In: Optical Society of America. Journal A. - 1084-7529 .- 1520-8532. ; 31:2, s. 217-226
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Journal article (peer-reviewed)abstract
- Optical coherence tomography (OCT) is useful for materials defect analysis and inspection with the additional possibility of quantitative dimensional metrology. Here, we present an automated image-processing algorithm for OCT analysis of roll-to-roll multilayers in 3D manufacturing of advanced ceramics. It has the advantage of avoiding filtering and preset modeling, and will, thus, introduce a simplification. The algorithm is validated for its capability of measuring the thickness of ceramic layers, extracting the boundaries of embedded features with irregular shapes, and detecting the geometric deformations. The accuracy of the algorithm is very high, and the reliability is better than 1 mu m when evaluating with the OCT images using the same gauge block step height reference. The method may be suitable for industrial applications to the rapid inspection of manufactured samples with high accuracy and robustness.
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