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Topic review
Updated time: 28 Sep 2021
Submitted by: Mustapha Jouiad
Definition: Two-dimensional (2D) materials are generally defined as crystalline substances with a few atoms thickness.Two-dimensional transition metal dichalcogenide (2D-TMDs) semiconducting (SC) materials have exhibited unique optical and electrical properties. The layered configuration of the 2D-TMDs materials is at the origin of their strong interaction with light and the relatively high mobility of their charge carriers, which in turn prompted their use in many optoelectronic applications, such as ultra-thin field-effect transistors, photo-detectors, light emitting diode, and solar-cells. Generally, 2D-TMDs form a family of graphite-like layered thin semiconducting structures with the chemical formula of MX2, where M refers to a transition metal atom (Mo, W, etc.) and X is a chalcogen atom (Se, S, etc.). The layered nature of this class of 2D materials induces a strong anisotropy in their electrical, chemical, mechanical, and thermal properties. In particular, molybdenum disulfide (MoS2) is the most studied layered 2D-TMD.
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Topic review
Updated time: 23 Aug 2021
Definition: Relevant samples are described and various problems and challenges—including 3D Challenges of 3D imaging by optical sectioning, light scattering and phototoxicity—are addressed. Furthermore, enhanced methods of wide-field or laser scanning microscopy together with some relevant examples and applications are summarized. In the future one may profit from a continuous increase in microscopic resolution, but also from molecular sensing techniques in the nanometer range using e.g., non-radiative energy transfer (FRET).
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Topic review
Updated time: 24 Aug 2021
Submitted by: Gabino Torres-Vega
Definition: We introduce finite-differences derivatives intended to be exact when applied to the real exponential function. We want to recover the known results of continuous calculus with our finite differences derivatives but in a discrete form. The purpose of this work is to have a discrete momentum operator suitable for use as an operator in discrete quantum mechanics theory.
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Topic review
Updated time: 08 Oct 2021
Submitted by: Xiang Jiang
Definition: Acoustic emission (AE) spectroscopy has become the method of choice in many fieldsbecause it is highly sensitive. For example, the AE system constructed by the Vallen company, Germany, has a sampling rate that can reach up to 10 MHz, an arrival time resolution of 100 ns, and an energy resolution of 1.8 × 10−18V2s (i.e., in the attojoule regime, aJ) referred to sensor signal at 34 dB preamplifier gain. A previous study showed simultaneous measurements of the avalanche of stress and AE during mechanically induced twin boundary motion in a shape memory alloy.
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Topic review
Updated time: 25 Jun 2021
Submitted by: Giorgio Palma
Definition: Metamaterials, man-made composites that are scaled smaller than the wavelength, have demonstrated a huge potential for application in acoustics, allowing the production of sub-wavelength acoustic absorbers, acoustic invisibility, perfect acoustic mirrors and acoustic lenses for hyper focusing, and acoustic illusions and enabling new degrees of freedom in the control of the acoustic field. The zero, or even negative, refractive sound index of metamaterials offers possibilities for the control of acoustic patterns and sound at sub-wavelength scales. The potential of metamaterial-based technologies has recently caught the interest of the aeronautics community. Their effect in the presence of realistic flows in the surrounding domains, with boundary layer, turbulence, is currently a hot research topic. The interaction with flow requires a careful design of the metamaterial to avoid detrimental effects and enabling the device maximum capabilities in aeronautics.
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Topic review
Updated time: 24 Aug 2021
Submitted by: Rajesh Kumar Mishra
Definition: Recent advancement in controlling noise through sound absorption provides an opportunity to investigate various porous materials including fiber-based composites. Natural-fiber-based composites exhibit relatively good sound absorption capability due to their porous structure. Surface modification by alkali treatment can enhance the sound absorption performance. These materials can be used in buildings and interiors for efficient sound insulation. Natural-fiber-based composites have advantages such as high abrasive resistance, low emission of toxic fumes with heat, high specific strength, light weight, low cost, and eco-friendliness. Very rapid growth has been observed in the innovations and use of natural-fiber-based materials and composites for acoustic applications.
Entry Collection : Environmental Sciences
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Topic review
Updated time: 14 Apr 2021
Submitted by: Meishan Zhao
Definition: Goos–Hänchen effect was an important optical phenomenon. When an optical wave propagates from a denser medium to a thinner medium, the total reflection generates coherent interference. The final propagated wave yields a lateral displacement relative to the incidence wave at the interface. Even though optics has a coherent effect on the total reflection of a finite-sized wave and an acoustic wave is incoherent with a non-total reflection of different frequency components, recent research shows that there is an analog Goos–Hänchen effect in acoustics.
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Topic review
Updated time: 09 Sep 2021
Submitted by: Ernesto Benini
Definition: Aeroelastic phenomena in turbomachinery are one of the most challenging problems to model using computational fluid dynamics (CFD) due to their inherent nonlinear nature, the difficulties in simulating fluid–structure interactions and the considerable computational requirements. Nonetheless, accurate modelling of self-sustained flow-induced vibrations, known as flutter, has proved to be crucial in assessing stability boundaries and extending the operative life of turbomachinery. Flutter avoidance and control is becoming more relevant in compressors and fans due to a well-established trend towards lightweight and thinner designs that enhance aerodynamic efficiency.
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Topic review
Updated time: 24 Aug 2021
Submitted by: Arunas Ramanavicius
Definition: Amperometric biosensors and biofuel cells are mostly based on immobilized enzymes or living cells. Among the many oxidoreductases, glucose oxidase (GOx) is used mostly in biosensor design. The same GOx can be well applied for the development of biofuel cells and self-charging capacitors based on the operation of biofuel cells.
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Biography
Updated time: 29 Oct 2020
Submitted by: Anan Yaghmur
Abstract: Anan Yaghmur is associate professor at the Department of Pharmacy, Faculty of Health & Medical Sciences, University of Copenhagen. He is also serving as a referee for at least 12 prominent journals including ACS NANO & ACS Applied Materials and Interfaces, Soft Matter, PLoS ONE, PCCP, Chemical Communications, Journal of Physical Chemistry B, and Langmuir. In addition to the evaluation of grant applications for scientific funding bodies. Anan Yaghmur has extensive expertise and know-how in formulation and nanostructural characterization of safe and efficient drug nanocarriers based on self-assembled lyotropic liquid crystalline systems and their dispersions (cubosomes and hexosomes).
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