Study of the microscopic mechanism of Ir(ppy)$_{3}$ regulating exciton splitting and luminescence process in Rubrene

It was Niihara et al. who first discovered that the fracture strength of Al2O3 can be increased by incorporating as little as 5 vol.% of nano-size SiC particles (>1000 MPa), and that the strength would be improved further by a simple annealing procedure (>1500 MPa). This discovery has stimulated intense interest on Al2O3/SiC nanocomposites. Recent indentation studies by Fang et al. have shown that residual stress relief was more difficult in the nanocomposite than in pure Al2O3. In the present work, TEM was employed to investigate the microscopic mechanism(s) for the difference in the residual stress recovery in these two materials.Bulk samples of hot-pressed single phase Al2O3, and Al2O3 containing 5 vol.% 0.15 μm SiC particles were simultaneously polished with 15 μm diamond compound. Each sample was cut into two pieces, one of which was subsequently annealed at 1300° for 2 hours in flowing argon. Disks of 3 mm in diameter were cut from bulk samples.

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The Influence of Drying-Wetting Cycles on the Suction Stress of Compacted Loess and the Associated Microscopic Mechanism

Water ◽

10.3390/w13131809 ◽

2021 ◽

Vol 13 (13) ◽

pp. 1809

Author(s):

Yongpeng Nie ◽

Wankui Ni ◽

Xiangning Li ◽

Haiman Wang ◽

Kangze Yuan ◽

...

Keyword(s):

Filter Paper ◽

Pore Diameter ◽

Matric Suction ◽

Microscopic Mechanism ◽

Suction Stress ◽

Dominant Soil ◽

Before And After ◽

Soil Pores ◽

Paper Method ◽

Compacted Loess

To better understand and analyze the unsaturated stability of loess filling body, it is necessary to study the changes in suction stress before and after the drying-wetting cycles. In this study, the SWCC of compacted loess before and after drying-wetting cycles was tested using the filter paper method. Then, the suction stress was calculated and the microstructure of the loess sample was determined by the SEM and NMR. The results showed that the drying-wetting cycles had an important influence on the SSCC and microstructure of compacted loess. The change in suction stress before and after the drying-wetting cycles can be well explained by the loess microstructure. The drying-wetting cycles did not significantly change the basic trend of the compacted loess’s SSCC, but it increased the porosity and the dominant pore diameter of loess, and reduced the suction stress under the same matric suction. The main significant change in suction stress with matric suction occurred within the range of the dominant soil pores. The larger the dominant pore diameter, the smaller the suction stress under the same matric suction. In addition, this study proposes a new method for calculating suction stress based on the PSD parameters.

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Gate Control of Superconductivity in Mesoscopic All-Metallic Devices

Materials ◽

10.3390/ma14051243 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1243

Author(s):

Claudio Puglia ◽

Giorgio De Simoni ◽

Francesco Giazotto

Keyword(s):

Probability Distributions ◽

Superconducting Properties ◽

Microscopic Mechanism ◽

Technological Potential ◽

Half Wave ◽

Thermal Origin ◽

Gate Control ◽

Titanium Wire ◽

Field Emission Of Electrons ◽

Gating Effect

The possibility to tune, through the application of a control gate voltage, the superconducting properties of mesoscopic devices based on Bardeen–Cooper–Schrieffer metals was recently demonstrated. Despite the extensive experimental evidence obtained on different materials and geometries, a description of the microscopic mechanism at the basis of such an unconventional effect has not been provided yet. This work discusses the technological potential of gate control of superconductivity in metallic superconductors and revises the experimental results, which provide information regarding a possible thermal origin of the effect: first, we review experiments performed on high-critical-temperature elemental superconductors (niobium and vanadium) and show how devices based on these materials can be exploited to realize basic electronic tools, such as a half-wave rectifier. Second, we discuss the origin of the gating effect by showing gate-driven suppression of the supercurrent in a suspended titanium wire and by providing a comparison between thermal and electric switching current probability distributions. Furthermore, we discuss the cold field-emission of electrons from the gate employing finite element simulations and compare the results with experimental data. In our view, the presented data provide a strong indication regarding the unlikelihood of the thermal origin of the gating effect.

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Microscopic mechanism of adatom diffusion on stepped SiC surfaces revealed by first-principles calculations

Applied Surface Science ◽

10.1016/j.apsusc.2021.149927 ◽

2021 ◽

pp. 149927

Author(s):

Kaori Seino ◽

Atsushi Oshiyama

Keyword(s):

First Principles ◽

First Principles Calculations ◽

Microscopic Mechanism ◽

Adatom Diffusion

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Mechanical behavior of frozen soil improved with sulphoaluminate cement and its microscopic mechanism

Scientific Reports ◽

10.1038/s41598-020-73148-3 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Zhenhua Yin ◽

Hu Zhang ◽

Jianming Zhang ◽

Mingtang Chai

Keyword(s):

Mechanical Properties ◽

Mechanical Behavior ◽

Soil Improvement ◽

Particle Size Analysis ◽

Frozen Soil ◽

Size Analysis ◽

Permafrost Soil ◽

Compression Tests ◽

Microscopic Mechanism ◽

Sulphoaluminate Cement

Abstract The foundation of constructions built in the permafrost areas undergo considerable creeping or thawing deformation because of the underlying ice-rich permafrost. Soil improvement may be of advantage in treating ice-rich permafrost at shallow depth. Sulphoaluminate cement was a potential material to improve frozen soil. Simultaneously, two other cements, ordinary Portland cement and Magnesium phosphate cement were selected as the comparison. The mechanical behavior of modified frozen soil was studied with thaw compression tests and unconfined compression strength tests. Meanwhile, the microscopic mechanism was explored by field emission scanning electron microscopy, particle size analysis and X-ray diffractometry. The results showed Sulphoaluminate cement was useful in reducing the thaw compression deformation and in enhancing the strength of the frozen soil. The improvement of the mechanical behavior depended mainly on two aspects: the formation of structural mineral crystals and the agglomeration of soil particles. The two main factors contributed to the improvement of mechanical properties simultaneously. The thicker AFt crystals result in a higher strength and AFt plays an important role in improving the mechanical properties of frozen soils.The study verified that Sulphoaluminate cement was an excellent stabilizer to improve ice-rich frozen soils.

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The H+N2O→OH(2ΠΩ, v′, N′)+N2 reaction: the microscopic mechanism at 1.5 eV

Physical Chemistry Chemical Physics ◽

10.1039/a907965c ◽

2000 ◽

Vol 2 (4) ◽

pp. 715-722 ◽

Cited By ~ 2

Author(s):

Mark Brouard ◽

Itamar Burak ◽

Simon D. Gatenby

Keyword(s):

Microscopic Mechanism

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II. Microscopic mechanism

Philosophical Magazine A ◽

10.1080/01418618808210426 ◽

1988 ◽

Vol 58 (3) ◽

pp. 491-505 ◽

Cited By ~ 42

Author(s):

M. Carrard ◽

J. L. Martin

Keyword(s):

Microscopic Mechanism

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Microscopic Mechanism of Specific Peptide Adhesion to Semiconductor Substrates

Angewandte Chemie International Edition ◽

10.1002/anie.201000984 ◽

2010 ◽

Vol 49 (49) ◽

pp. 9530-9533 ◽

Cited By ~ 43

Author(s):

Michael Bachmann ◽

Karsten Goede ◽

Annette G. Beck-Sickinger ◽

Marius Grundmann ◽

Anders Irbäck ◽

...

Keyword(s):

Microscopic Mechanism ◽

Semiconductor Substrates ◽

Specific Peptide

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Superconducting coherence length of hole-doped cuprates obtained from electron–boson spectral density function

Scientific Reports ◽

10.1038/s41598-021-91163-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jungseek Hwang

Keyword(s):

Spectral Density ◽

Coherence Length ◽

Cooper Pair ◽

Average Frequency ◽

Spin Fluctuations ◽

Fermi Velocity ◽

Cooper Pairs ◽

Spectroscopic Techniques ◽

Microscopic Mechanism ◽

Superconducting Coherence Length

AbstractElectron–boson spectral density functions (EBSDFs) can be obtained from measured spectra using various spectroscopic techniques, including optical spectroscopy. EBSDFs, known as glue functions, are suggested to have a magnetic origin. Here, we investigated EBSDFs obtained from the measured optical spectra of hole-doped cuprates with wide doping levels, from underdoped to overdoped cuprates. The average frequency of an EBSDF provides the timescale for the spin fluctuations to form Cooper pairs. This timescale is directly associated with retarded interactions between electrons. Using this timescale and Fermi velocity, a reasonable superconducting coherence length, which reflects the size of the Cooper pair, can be extracted. The obtained coherence lengths were consistent with those measured via other experimental techniques. Therefore, the formation of Cooper pairs in cuprates can be explained by spin fluctuations, the timescales of which appear in EBSDFs. Consequently, EBSDFs provide crucial information on the timescale of the microscopic mechanism of Cooper pair formation.

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Molecular Dynamics Study of Microscopic Mechanism of Diffusion in Li2SiO3 System

Zeitschrift für Naturforschung A ◽

10.1515/zna-1991-0710 ◽

1991 ◽

Vol 46 (7) ◽

pp. 616-620 ◽

Cited By ~ 9

Author(s):

Junko Habasaki

Keyword(s):

Molecular Dynamics ◽

Coordination Number ◽

Md Simulation ◽

Mean Square Displacement ◽

Mean Square ◽

Lithium Ions ◽

Microscopic Mechanism ◽

Trapping Model ◽

The Mean

MD simulation has been performed to learn the microscopic mechanism of diffusion of ions in the Li2SiO3 system. The motion of lithium ions can be explained by the trapping model, where lithium is trapped in the polyhedron and moves with fluctuation of the coordination number. The mean square displacement of lithium was found to correlate well with the net changes in coordination number.

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