scholarly journals Magnetotail reconnection onset caused by electron kinetics with a strong external driver

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
San Lu ◽  
Rongsheng Wang ◽  
Quanming Lu ◽  
V. Angelopoulos ◽  
R. Nakamura ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Crucial Role ◽  
Direct Evidence ◽  
Explosive Energy ◽  
Particle In Cell ◽  
Electron Kinetics ◽  
Unstable Configuration ◽  
External Driver ◽  
Magnetotail Reconnection

Abstract Magnetotail reconnection plays a crucial role in explosive energy conversion in geospace. Because of the lack of in-situ spacecraft observations, the onset mechanism of magnetotail reconnection, however, has been controversial for decades. The key question is whether magnetotail reconnection is externally driven to occur first on electron scales or spontaneously arising from an unstable configuration on ion scales. Here, we show, using spacecraft observations and particle-in-cell (PIC) simulations, that magnetotail reconnection starts from electron reconnection in the presence of a strong external driver. Our PIC simulations show that this electron reconnection then develops into ion reconnection. These results provide direct evidence for magnetotail reconnection onset caused by electron kinetics with a strong external driver.

scholarly journals On the Origin of Tetraploid Vernal Grasses (Anthoxanthum) in Europe

Genes ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 966
Author(s):  
Zuzana Chumová ◽  
Terezie Mandáková ◽  
Pavel Trávníček
Keyword(s):  
Flow Cytometry ◽  
In Situ Hybridization ◽  
Crucial Role ◽  
Evolutionary History ◽  
Essential Role ◽  
Grass Species ◽  
Polyploid Species ◽  
Anthoxanthum Odoratum ◽  
European Populations

Polyploidy has played a crucial role in the evolution of many plant taxa, namely in higher latitudinal zones. Surprisingly, after several decades of an intensive research on polyploids, there are still common polyploid species whose evolutionary history is virtually unknown. Here, we addressed the origin of sweet vernal grass (Anthoxanthum odoratum) using flow cytometry, DNA sequencing, and in situ hybridization-based cytogenetic techniques. An allotetraploid and polytopic origin of the species has been verified. The chromosome study reveals an extensive variation between the European populations. In contrast, an autopolyploid origin of the rarer tetraploid vernal grass species, A. alpinum, has been corroborated. Diploid A. alpinum played an essential role in the polyploidization of both European tetraploids studied.

In situ lithiated FeF3/C nanocomposite as high energy conversion-reaction cathode for lithium-ion batteries

2016 ◽  
Vol 307 ◽  
pp. 435-442 ◽  
Author(s):  
Xiulin Fan ◽  
Yujie Zhu ◽  
Chao Luo ◽  
Tao Gao ◽  
Liumin Suo ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Lithium Ion Batteries ◽  
Lithium Ion ◽  
High Energy ◽  
Conversion Reaction

Green rust as a precursor for magnetite: an in situ synchrotron based study

2008 ◽  
Vol 72 (1) ◽  
pp. 201-204 ◽  
Author(s):  
A. Sumoondur ◽  
S. Shaw ◽  
I. Ahmed ◽  
L. G. Benning
Keyword(s):  
Direct Evidence ◽  
Green Rust ◽  
Stable Phase ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Subsequent Transformation ◽  
Rapid Formation ◽  
Reaction Proceeds

AbstractIn this study, direct evidence for the formation of magnetite via a green rust intermediate is reported. The Fe(II) induced transformation of ferrihydrite, was quantified in situ and under O2-free conditions using synchrotron-based time-resolved energy dispersive X-ray diffraction. At pH 9 and Fe(II)/Fe(III) ratios of 0.5 and 1, rapid growth (6 min) of sulphate green rust and its subsequent transformation to magnetite was observed. Electron microscopy confirmed these results, showing the initial rapid formation of hexagonal sulphate green rust particles, followed by the corrosion of the green rust as magnetite growth occurred, indicating that the reaction proceeds via a dissolution-reprecipitation mechanism. At pH 7 and Fe(II)/Fe(III) ratio of 0.5, sulphate green rust was the stable phase, with no transformation to magnetite.

scholarly journals Measurement Uncertainty of Radiated Electromagnetic Emissions in In Situ Tests of Wind Energy Conversion Systems

2018 ◽  
Vol 16 ◽  
pp. 13-22 ◽  
Author(s):  
Sebastian Koj ◽  
Axel Hoffmann ◽  
Heyno Garbe
Keyword(s):  
Wind Energy ◽  
Measurement Uncertainty ◽  
Energy Conversion ◽  
Wind Velocity ◽  
Standard Procedure ◽  
In Situ Tests ◽  
Wind Energy Conversion ◽  
Wind Energy Conversion Systems ◽  
Energy Conversion Systems

Abstract. The electromagnetic (EM) emissions of wind energy conversion systems (WECS) are evaluated in situ. Results of in situ tests, however, are only valid for the examined equipment under test (EUT) and cannot be applied to series production as samples, as the measurement uncertainty for in situ environment is not characterized. Currently measurements must be performed on each WECS separately, this is associated with significant costs and time requirement to complete. Therefore, in this work, based on the standard procedure according to the “Guide to the Expression of Uncertainty” (GUM, 2008) the measurement uncertainty is characterized. From current normative situation obtained influences on the measurement uncertainty: wind velocity and undefined ground are evaluated. The influence of increased wind velocity on the measurement uncertainty is evaluated with an analytical approach making use of the dipole characteristic. A numerically evaluated model provides information about the expected uncertainty due to reflection on different textures and varying values of relative ground moisture. Using a classical reflection law based approach, the simulation results are validated. Thanks to the presented methods, it is possible to successfully characterize the measurement uncertainty of in situ measurements of WECS's EM emissions.

Initial Stages of InAs Quantum Dots Evolution in GaAs/AlAs Matrixes

2002 ◽  
Vol 749 ◽  
Author(s):  
Michael Yakimov ◽  
Vadim Tokranov ◽  
Alex Katnelson ◽  
Serge Oktyabrsky
Keyword(s):  
Quantum Dots ◽  
Direct Evidence ◽  
Matrix Material ◽  
Single Layer ◽  
High Energy ◽  
Inas Quantum Dots ◽  
Auger Signal ◽  
The Matrix ◽  
Growth Evolution

ABSTRACTWe have studied the first phases of post-growth evolution of InAs quantum dots (QDs) using in-situ Auger electron spectroscopy in conjunction with Reflection High Energy Electron Diffraction (RHEED). Direct evidence for InAs intermixing with about 6ML (monolayers) of the matrix material is found from Auger signal behavior during MBE overgrowth of InAs nanostructures. Re-establishment of 2D growth mode by overgrowth with GaAs or AlAs was monitored in single-layer and multi-layer QD structures using RHEED. Decay process of InAs QDs on the surface is found to have activation energy of about 1.1 eV that corresponds to In intermixing with the matrix rather than evaporation from the surface.

In situ growth of g-C3N4 on clay minerals of kaolinite, sepiolite, and talc for enhanced solar photocatalytic energy conversion

2022 ◽  
Vol 216 ◽  
pp. 106337
Author(s):  
Yunhui Chen ◽  
Liping Wen ◽  
Jinxin Chen ◽  
He'an Luo ◽  
Jikai Liu
Keyword(s):  
Energy Conversion ◽  
Clay Minerals ◽  
In Situ Growth

Evidence for ultrahigh-pressure metamorphism discovered in the Appalachian orogen

Geology ◽  
2020 ◽  
Vol 48 (10) ◽  
pp. 947-951
Author(s):  
Joseph P. Gonzalez ◽  
Suzanne L. Baldwin ◽  
Jay B. Thomas ◽  
William O. Nachlas ◽  
Paul G. Fitzgerald
Keyword(s):  
Direct Evidence ◽  
Ultrahigh Pressure ◽  
Garnet Growth ◽  
Uhp Metamorphism ◽  
Ultrahigh Pressure Metamorphism ◽  
Iapetus Ocean ◽  
Taconic Orogeny ◽  
Growth History ◽  
Appalachian Orogen

Abstract The Appalachian orogen has long been enigmatic because, compared to other parts of the Paleozoic orogens that formed following the subduction of the Iapetus Ocean, direct evidence for ultrahigh-pressure (UHP) metamorphism has never been found. We report the first discovery of coesite in the Appalachian orogen in a metapelite from the mid-Ordovician (Taconic orogeny) Tillotson Peak Complex in Vermont (USA). Relict coesite occurs within a bimineralic SiO2 inclusion in garnet. In situ elastic barometry and trace-element thermometry allow reconstruction of the garnet growth history during prograde metamorphism. The data are interpreted to indicate garnet nucleation and crystallization during blueschist- to eclogite-facies subduction zone metamorphism, followed by garnet rim growth at UHP conditions of > 28 kbar and > 530 ° C. Results provide the first direct evidence that rocks of the Appalachian orogen underwent UHP metamorphism to depths of > 75 km and warrant future studies that constrain the extent of UHP metamorphism.

X-Ray Reflectivity Study of Single- and Bicrystals of Gold

1990 ◽  
Vol 208 ◽  
Author(s):  
M. R. Fitzsimmons ◽  
E. Burkel ◽  
J. Peisl
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Diffuse Scattering ◽  
Direct Evidence ◽  
X Ray ◽  
Specular Reflectivity ◽  
Boundary Measurements

ABSTRACTX-ray reflectivity techniques have been used to characterize the surfaces of 0.4µm thick Au films epitaxially grown on single-crystals of NaCl. Measurements of both the specular and non-specular reflectivity suggest that the Au surface is very rough. The nonspecular reflectivity provides valuable information about the correlation of the heights at different points on the surface. The first in situ reflectivity study of the formation and destruction of a grain boundary shows direct evidence for the existence of diffuse scattering from the grain boundary. Measurements of several [0011 twist grain boundaries suggest that the roughness and texture of an interface depends upon the geometrical orientation of the surrounding substrates.

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