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| 2. |
- Giang, Tony, et al.
(author)
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Outflowing protons and heavy ions as a source for the sub-keV ringcurrent
- 2009
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In: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 27:2, s. 839-849
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Journal article (peer-reviewed)abstract
- Data from the Cluster CIS instrument have been used for studying proton and heavy ion (O+ and He+ ) char- acteristics of the sub-keV ring current. Thirteen events with dispersed heavy ions (O+ and He+ ) were identified out of two years (2001 and 2002) of Cluster data. Allevents took place during rather geomagnetically quiet periods. Three of those events have been investigated in detail: 21 August 2001, 26 November 2001 and 20 February 2002. These events were chosen from varying magnetic local times (MLT), and they showed different characteristics. In this article, we discuss the potential source for sub-keV ring current ions. We show that: (1) outflows of terrestrialsub-keV ions are supplied to the ring current also during quiet geomagnetic conditions; (2) the composition of the out-flow implies an origin that covers an altitude interval from the low-altitude ionosphere to the plasmasphere, and (3) terrestrial ions are moving upward along magnetic field lines, at times forming narrow collimated beams, but frequently also as broad beams. Over time, the ion beams are expected to gradually become isotropised as a result of wave-particleinteraction, eventually taking the form of isotropic drifting sub-keV ion signatures. We argue that the sub-keV energy-time dispersed signatures originate from field-aligned terrestrial ion energising and outflow, which may occur at all local times and persist also during quiet times.
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| 3. |
- Li, Cuiling, et al.
(author)
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Electrochemical synthesis of mesoporous gold films toward mesospace-stimulated optical properties
- 2015
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 6
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Journal article (peer-reviewed)abstract
- Mesoporous gold (Au) films with tunable pores are expected to provide fascinating optical properties stimulated by the mesospaces, but they have not been realized yet because of the difficulty of controlling the Au crystal growth. Here, we report a reliable soft-templating method to fabricate mesoporous Au films using stable micelles of diblock copolymers, with electrochemical deposition advantageous for precise control of Au crystal growth. Strong field enhancement takes place around the center of the uniform mesopores as well as on the walls between the pores, leading to the enhanced light scattering as well as surface-enhanced Raman scattering (SERS), which is understandable, for example, from Babinet principles applied for the reverse system of nanoparticle ensembles.
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| 4. |
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| 5. |
- Schillings, Audrey, et al.
(author)
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The fate of O+ ions observed in the plasma mantle: particle tracing modelling and cluster observations
- 2020
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In: Annales Geophysicae. - : Copernicus Publications. - 0992-7689 .- 1432-0576. ; 38:3, s. 645-656
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Journal article (peer-reviewed)abstract
- Ion escape is of particular interest for studying the evolution of the atmosphere on geological timescales. Previously, using Cluster-CODIF data, we investigated the oxygen ion outflow from the plasma mantle for different solar wind conditions and geomagnetic activity. We found significant correlations between solar wind parameters, geomagnetic activity (Kp index), and the O+ outflow. From these studies, we suggested that O+ ions observed in the plasma mantle and cusp have enough energy and velocity to escape the magnetosphere and be lost into the solar wind or in the distant magnetotail. Thus, this study aims to investigate where the ions observed in the plasma mantle end up. In order to answer this question, we numerically calculate the trajectories of O+ ions using a tracing code to further test this assumption and determine the fate of the observed ions. Our code consists of a magnetic field model (Tsyganenko T96) and an ionospheric potential model (Weimer 2001) in which particles initiated in the plasma mantle region are launched and traced forward in time. We analysed 131 observations of plasma mantle events in Cluster data between 2001 and 2007, and for each event 200 O+ particles were launched with an initial thermal and parallel bulk velocity corresponding to the velocities observed by Cluster. After the tracing, we found that 98 % of the particles are lost into the solar wind or in the distant tail. Out of these 98 %, 20 % escape via the dayside magnetosphere.
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| 7. |
- Wang, Hongjing, et al.
(author)
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Electrochemical Design of Mesoporous Pt-Ru Alloy Films with Various Compositions toward Superior Electrocatalytic Performance
- 2012
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In: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 18:41, s. 13142-13148
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Journal article (peer-reviewed)abstract
- Mesoporous PtRu alloy films with various compositions were synthesized by electrochemical plating in an aqueous surfactant solution. After the removal of surfactants, continuous mesoporous PtRu alloy films possessing uniform mesopores with diameter about 7 nm were obtained. The Ru content in the films could be controlled from 0 to 13 at?% by changing the precursor compositions. For all the films, the mesostructural periodicities and the mesopore sizes in the films were not changed. Due to the mesoporous structure and the doped Ru content, our mesoporous PtRu films showed superior electrocatalytic activity for methanol oxidation reaction in comparison with the commercially available Pt catalyst.
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| 8. |
- Wang, Hongjing, et al.
(author)
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Shape- and Size-Controlled Synthesis in Hard Templates : Sophisticated Chemical Reduction for Mesoporous Monocrystalline Platinum Nanoparticles
- 2011
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In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 133:37, s. 14526-14529
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Journal article (peer-reviewed)abstract
- Here we report a novel hard-templating strategy for the synthesis of mesoporous monocrystalline Pt nanopartides (NPs) with uniform shapes and sizes. Mesoporous Pt NPs were successfully prepared through controlled chemical reduction using ascorbic acid by employing 3D bicontinuous mesoporous silica (KIT-6) and 2D mesoporous silica (SBA-15) as a hard template. The particle size could be controlled by changing the reduction time. Interestingly, the Pt replicas prepared from KIT-6 showed polyhedral morphology. The single crystallinity of the Pt fcc structure coherently extended over the whole particle.
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| 9. |
- Wang, Hongjing, et al.
(author)
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Synthesis of Mesoporous Pt Films with Tunable Pore Sizes from Aqueous Surfactant Solutions
- 2012
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In: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 24:9, s. 1591-1598
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Journal article (peer-reviewed)abstract
- Platinum (Pt) is widely used as battery electrodes, catalysts for chemicals, and catalysts for exhaust gas decomposition in industries. Increasing need and very limited supply of rare Pt is a serious problem in the world. Here, we propose new synthetic way for reducing the use of Pt in a catalytic system by increasing the surface area and modifying the Pt surface structure. Several types of mesoporous Pt films with different pore sizes ranging from 5 to 30 nm are prepared by electrochemical plating in aqueous surfactant solutions. The mesopore walls are composed of connected Pt nanoparticles with around 3 nm in diameter. The Pt atomic crystallinity is coherently extending across over several Pt nanoparticles, showing a large number of atomic steps, which can accelerate methanol oxidation reaction. As a result of a high surface area and unique Pt surface, our mesoporous Pt film exhibits high potentiality as a superior electrocatalyst.
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| 10. |
- Wang, Tao, et al.
(author)
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A Co3O4-embedded porous ZnO rhombic dodecahedron prepared using zeolitic imidazolate frameworks as precursors for CO2 photoreduction
- 2016
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In: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 8:12, s. 6712-6720
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Journal article (peer-reviewed)abstract
- Metal-organic frameworks (MOFs) are attracting considerable attention for their use as both the precursor and the template to prepare metal oxides or carbon-based materials. For the first time in this paper, the core-shell ZIF-8@ZIF-67 crystals are thermally converted into porous ZnO@Co3O4 composites by combining a seed-mediated growth process with a two-step calcination. The designed porous ZnO@Co3O4 composites exhibited the highest photocatalytic activity with an excellent stability for the reduction of CO2 among the commonly reported composite photocatalysts. Their superior photocatalytic performance is demonstrated to be resulting from the unique porous structure of ZnO@Co3O4 and the co-catalytic function of Co3O4 which can effectively suppress the photocorrosion of ZnO.
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