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Stress Evolution during Ge Nanoparticles Growth in a SiO <sub/>2</sub> Matrix
摘要： Superstructures are explored that were obtained by multilayer magnetron deposition at room temperature of 20 SiO2 and SiO2:Ge bilayers, each 2 × 4 nm thick, and subsequently annealed in inert N2 atmosphere at different temperatures in the range of 500?750 °C. The structural and optical changes induced by annealing and the formation and growth of Ge nanoparticles (nps) from early clusters to their full growth and final dissolution were studied by the simultaneous grazing-incidence small- and wide-angle X-ray scattering, transmission electron microscopy, and (time-resolved) photoluminescence (PL). It is shown that in as-deposited multilayers aggregation of small clusters already occurred, and the clusters were reasonably well intercorrelated in the lateral plane. During annealing at Ta = 550 °C or higher temperatures, Ge nps start to form and remain partly amorphous at lower Ta but crystallize completely at about 600 °C. At even higher temperatures, the Ge nps dissolve and Ge diffuses out almost completely, leaving voids in the SiO2 matrix. Visible PL from the samples was detected and attributed to defects in the nps/matrix interface layers rather than to the nps itself because PL persisted even after Ge nps dissolution.
关键词： GIWAXS,photoluminescence,Ge nanoparticles,GISAXS,stress evolution,SiO2 matrix,TEM
更新于2025-09-11 14:15:04
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Fabricating Cu, Cu<sub>2</sub>O and Hybrid Cu-Cu<sub>2</sub>O nanoparticles in carbon matrix and exploring catalytic activity of oxygen and hydrogen evolution and green A<sup>3</sup>-coupling reaction
摘要： Hybrid Cu-Cu2O as well as Cu and Cu2O@C nanoparticles (NPs) encapsulated by carbon matrix have been synthesized and bifunctional electrocatalytic activity (OER and HER) and A3 coupling (three components reaction) were explored. Powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), and high resolution transmission electron microscopy (HR-TEM) studies were performed to analyse structure, chemical state, and size of the nanocatalysts. Hybrid Cu-Cu2O@C materials exhibited stronger electrocatalytic activity compared to pure phases whereas pure Cu and Cu2O@C NPs displayed better catalytic activity for A3 coupling reaction. Oxygen and hydrogen evolution reaction (OER and HER) showed enhanced current response (57.8 mA/cm2 and -172 mA/cm2) for hybrid NPs with higher Cu2O ratio. Thus, the present work investigated the role of Cu and Cu2O ratio for fabricating earth abundant cost effective nanocatalysts for OER, HER, and organic chemical transformation.
关键词： Water splitting,A3 coupling,Oxygen evolution reaction,Hydrogen evolution reaction,Cu-Cu2O nanoparticles,Electrocatalyst
更新于2025-09-10 09:29:36
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Encapsulation of Organic Dyes within an Electron-Deficient Redox Metal-Organic Tetrahedron for Photocatalytic Proton Reduction
摘要： The design of artificial systems that mimic highly evolved and finely tuned natural photosynthetic systems is a subject of intensive research. By incorporating electron-deficient anthraquinone within the ligand backbone, a redox-active Ni-based tetrahedron was developed as a redox vehicle for the construction of an artificial photosynthesis system. The tetrahedron can encapsulate fluorescein within its cavity for light-driven H2 evolution, with the turnover number reaching 1200 moles H2 per mole redox catalyst. This well-designed supramolecular system displayed a significantly superior activities compared with the reference mononuclear compound or introducing an inactive inhibitor (ATP), which confirmed this enzymatic photocatalytic behaviour.
关键词： light-driven H2 evolution,metal-organic tetrahedral,anthraquinone,supramolecular chemistry
更新于2025-09-10 09:29:36
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Optimization of Epsilon-and-mu-near-zero Refractive Index Photonic Structure to Design Unidirectional Transmission Device
摘要： In this study, we introduce a novel approach for designing an unidirectional transmission device by using a photonic crystal (PC) structure that exhibits the properties of epsilon-mu-near-zero media. The selected PC structure consists of dielectric rods and positions of certain preselected rods in y-direction are optimized via an evolutionary algorithm to obtain the unidirectional transmission of light. Finite-difference time-domain (FDTD) method is used to perform numerical analyses for the proposed device. In addition, experiments are carried out at microwave frequencies to demonstrate the unidirectional light transmission. It is shown that a good agreement between numerical calculations and experimental measurements is achieved.
关键词： phase shift,mode order converter,photonic crystals,differential evolution algorithm,integrated optics
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Analysis of Bucharest'S Land Cover Evolution Over A Period Of 33 Years Using Multi-Sensor Data
摘要： Past and current EO (Earth Observation) satellite missions have gathered huge amount of data during the past decades. This offers the opportunity to retrieve significant information concerning the evolution of land cover for almost any point of interest (POI) on Earth’s surface. This paper presents the evolution of land cover in the administrative area of Bucharest, Romania, over a timespan of 33 years. In order to achieve this goal we use data acquired by multiple EO missions such as: Landsat 5 TM (Thematic Mapper), 7 ETM+ (Enhanced Thematic Mapper Plus), 8 OLI/TIRS (Operational Land Imager/Thermal InfraRed Sensor) and Sentinel-2 MSI (Multi-Spectral Instrument). We compute several spectral indexes in order to obtain information regarding the surface coverage evolution for categories such as vegetation, water bodies and buildup.
关键词： land cover evolution,Landsat,Sentinel-2
更新于2025-09-10 09:29:36
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Multi-Party Energy Management and Economics of Integrated Energy Microgrid with PV/T and CHP system
摘要： Focusing on electricity and thermal energy requirement of contemporary buildings, a joint operation of photovoltaic thermal (PV/T) based prosumers and a Microturbine based combined heat and power (CHP) system has been presented to analyse the economics of grid-connected microgrid (MG) system. Bidirectional flow of electricity and heat model is considered and is optimally managed using price-based demand response (DR) scheme. Thermal storage is exploited to ward off the substantial amount of heat wastages that enhance the system's reliability during any disruption of microturbine. The objective functions of both prosumer and microgrid operator (MGO) are formulated as a profit maximization problem where they interact with each other on the basis of DR activity. To establish this strategic decision-making process, the system is modelled as a Stackelberg Equilibrium (SE) game, where MGO acts as a leader while PV/T prosumers act as a follower. The interaction or contribution of two players in a game is a problem of non-linear optimization which is solved by Differential Evolution (DE) algorithm. In the end, in a case study, it has been proved that the results are quite lucrative for the proposed model.
关键词： photovoltaic thermal (PV/T),Differential Evolution (DE),demand response (DR),Stackelberg Equilibrium (SE),microgrid (MG),combined heat and power (CHP)
更新于2025-09-10 09:29:36
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Effect of calcium oxide doping on the microstructure and optical properties of YAG transparent ceramics
摘要： Yttrium aluminium garnet (YAG, Y3Al5O12) transparent ceramics were fabricated by vacuum sintering the co-precipitated raw powders with calcium oxide (CaO) as the sintering aid. The influence of CaO content on the phase composition, particle size and the morphologies of resultant YAG powders, as well as the microstructural and optical properties of YAG ceramics, was investigated in detail. Our results show that with increasing of CaO additives, the particle size and agglomeration degree of the powders were slightly increased and the grain growth of the ceramics was inhibited. Specifically, the grain size initially decreased dramatically till reaching a minimum value of 1.85 μm with 0.3 at% CaO, then slightly increased. In addition, for YAG ceramics with a high CaO doping level, the existence of liquid phase was observed for the first time and its sintering mechanism was discussed. The excess of CaO causes the formation of grain boundary phases and residual pores, which are detrimental for maintaining higher optical quality of YAG ceramics. We obtained a fully dense and pore-free YAG ceramic with an in-line transmittance of 80.8% at 1100 nm by adopting 0.1 at% level of CaO during sintering of the green bodies at 1780°C for 20 h in vacuum.
关键词： Microstructure evolution,YAG transparent ceramic,Co-precipitation method,CaO additives
更新于2025-09-10 09:29:36
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Erratum: Modelling and interpreting spectral energy distributions of galaxies with beagle
摘要： The paper ‘Modelling and interpreting spectral energy distributions of galaxies with BEAGLE’ was published in MNRAS, 2016, 462 (Chevallard & Charlot 2016). During one of the revisions of the manuscript, the last term of equation (25) was inadvertently removed. The correct form of equation (25) is therefore log US = (cid:2) ?3.638 + 0.055 x + 0.680 x2 ?3.640 for x (cid:2) ?0.04, for x > ?0.04, where x = log(ZISM/Z(cid:2)).
关键词： methods: data analysis,methods: statistical,dust, extinction,galaxies: stellar content,H II regions,galaxies: evolution
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE Congress on Evolutionary Computation (CEC) - Rio de Janeiro (2018.7.8-2018.7.13)] 2018 IEEE Congress on Evolutionary Computation (CEC) - Confidence Measures for Carbon-Nanotube / Liquid Crystals Classifiers
摘要： This paper focuses on a performance analysis of single-walled-carbon-nanotube / liquid crystal classifiers produced by evolution in materio. A new confidence measure is proposed in this paper. It is different from statistical tools commonly used to evaluate the performance of classifiers in that it is based on physical quantities extracted from the composite and related to its state. Using this measure, it is confirmed that in an un-trained state, ie: before being subjected to an algorithm-controlled evolution, the carbon-nanotube-based composites classify data at random. The training, or evolution, process brings these composites into a state where the classification is no longer random. Instead, the classifiers generalise well to unseen data and the classification accuracy remains stable across tests. The confidence measure associated with the resulting classifier’s accuracy is relatively high at the classes’ boundaries, which is consistent with the problem formulation.
关键词： confidence measure,evolution in materio,classifiers,liquid crystal,single-walled-carbon-nanotube
更新于2025-09-10 09:29:36
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Extraction of tight binding parameters from in-situ ARPES on the continuously doped surface of cuprates
摘要： Recently we developed a technique of ozone/vacuum annealing to continuously change the doping level of the surface of Bi2Sr2CaCu2O8+x and measured a nearly whole superconducting dome on one surface by in-situ angle-resolved photoemission spectroscopy [arXiv: 1805.06450]. Here we study the evolution of the electronic structures of Bi2Sr2CaCu2O8+x using this technique together with tight binding fits. The tight binding parameters are extracted to study their evolution with doping.
关键词： cuprates,doping evolution,ARPES,electronic structures,tight binding
更新于2025-09-10 09:29:36