10,602 research outputs found
Preparation and field-induced electrical properties of perovskite relaxor ferroelectrics
(111)-oriented and random oriented Pb0.8Ba0.2ZrO3 (PBZ) perovskite relaxor ferroelectric thin films were fabricated on Pt(111)/TiOx/SiO2/Si substrate by sol-gel method. Nano-scaled antiferroelectric and ferroelectric two-phase coexisted in both (111)-oriented and random oriented PBZ thin film. High dielectric tunability (i = 75%, E = 560 kV/ cm ) and figure-of-merit (FOM ~ 236) at room temperature was obtained in (111)-oriented thin film. Meanwhile, giant electrocaloric effect (ECE) (AT = 45.3 K and AS = 46.9 JK-1kg-1 at 598 kVcm-1) at room temperature (290 K), rather than at its Curie temperature (408 K), was observed in random oriented Pb0.8Ba0.2ZrO3 (PBZ) thin film, which makes it a promising material for the application to cooling systems near room temperature. The giant ECE as well as high dielectric tunability are attributed to the coexistence of AFE and FE phases and field-induced nano-scaled AFE to FE phase transition
Shadows of rotating Hayward-de Sitter black holes with astrometric observables
Motivated by recent work on rotating black hole shadow [Phys. Rev. D101,
084029 (2020)], we investigate the shadow behaviors of rotating Hayward-de
Sitter black hole for static observers at a finite distance in terms of
astronomical observables. This paper uses the newly introduced distortion
parameter in [arXiv:2006.00685] to describe the shadow's shape quantitatively.
We show that the spin parameter would distort shadows and the magnetic monopole
charge would increase the degree of deformation. At the same time, the
distortion could be relieved because of the cosmological constant and the
distortion would increase with the distance from the black hole. Besides, the
spin parameter, magnetic monopole charge and cosmological constant increase
will cause the shadow to shrink.Comment: 16 pages, 6 figure
Empirical research on the evaluation model and method of sustainability of the open source ecosystem
The development of open source brings new thinking and production modes to software engineering and computer science, and establishes a software development method and ecological environment in which groups participate. Regardless of investors, developers, participants, and managers, they are most concerned about whether the Open Source Ecosystem can be sustainable to ensure that the ecosystem they choose will serve users for a long time. Moreover, the most important quality of the software ecosystem is sustainability, and it is also a research area in Symmetry. Therefore, it is significant to assess the sustainability of the Open Source Ecosystem. However, the current measurement of the sustainability of the Open Source Ecosystem lacks universal measurement indicators, as well as a method and a model. Therefore, this paper constructs an Evaluation Indicators System, which consists of three levels: The target level, the guideline level and the evaluation level, and takes openness, stability, activity, and extensibility as measurement indicators. On this basis, a weight calculation method, based on information contribution values and a Sustainability Assessment Model, is proposed. The models and methods are used to analyze the factors affecting the sustainability of Stack Overflow (SO) ecosystem. Through the analysis, we find that every indicator in the SO ecosystem is partaking in different development trends. The development trend of a single indicator does not represent the sustainable development trend of the whole ecosystem. It is necessary to consider all of the indicators to judge that ecosystem’s sustainability. The research on the sustainability of the Open Source Ecosystem is helpful for judging software health, measuring development efficiency and adjusting organizational structure. It also provides a reference for researchers who study the sustainability of software engineering
Optical properties of a Brane-World black hole as photons couple to the Weyl tensor
In this article, we have investigated the equations of motion of the photons
coupled to Weyl tensor by the geometric optics approximation and the
corresponding shadow in a Brane-World black hole spacetime. It is shown that
there exists a double shadow for a black hole since the coupling photons with
different polarization directions propagate along different paths in the
spacetime. Furthermore, we discuss the effects of the metric parameter
related to the cosmological constant, X-cold dark matter parameter and
the coupling parameter on the umbra (the overlap region of the double
shadow) and the penumbra. We also obtain the finite-distance corrections to the
deflection angle of light in the Brane-World black hole spacetime as the
photons coupled to Weyl tensor by using a recent geometric method.Comment: arXiv admin note: text overlap with arXiv:1502.01088,
arXiv:1611.08783, arXiv:1606.04634 by other author
Analysis of Alphalactalbumin and Betalactoglobulin from the Rehydration of Bovine Colostrum Powder Using Cloud Point Extraction and Mass Spectrometry
Alphalactalbumin (α-La) and betalactoglobulin (β-Lg) in the rehydration of bovine colostrum powder were successfully separated by cloud point extraction using a nonionic surfactant Triton X-114. The effects of different factors, including the surfactant concentration, sample volume, electrolyte, and pH were discussed. The optimized conditions for cloud point extraction of alphalactalbumin (α-La) and betalactoglobulin (β-Lg) can be concluded that the best surfactant is 1% (w/v) Triton X-114, 200 μL of sample volume, 150 mmol/L NaCl, and 6% (w/v) sucrose. After cloud point extraction, the capillary electrophoresis is used to check the efficiency of the extraction procedure. The results had been effectively confirmed by the characterization with matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS)
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