The control of thermal radiation is of great current importance for applications such as energy conversions and radiative cooling. Here we show theoretically that the thermal emission of a finite-size blackbody emitter can be enhanced in a thermal extraction scheme, where one places the emitter in optical contact with an extraction device consisting of a transparent object, as long as both the emitter and the extraction device have an internal density of state higher than vacuum, and the extraction device has an area larger than the emitter and moreover has a geometry that enables light extraction. As an experimental demonstration of the thermal extraction scheme, we observe a four-fold enhancement of the far-field thermal emission of a carbon-black emitter having an emissivity of 0.85.
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http://dx.doi.org/10.1038/ncomms2765 | DOI Listing |
Molecules
December 2024
Facultad de Ingeniería Química, Universidad Pontificia Bolivariana, Circular 1 N 70-01, Medellín 050031, Colombia.
The agroindustry generates substantial quantities of byproducts, particularly in coffee production, which yields significant waste, most notably spent coffee grounds (SCGs). This study explores the potential of SCGs as a versatile resource for applications in both food and nonfood sectors. A comprehensive chemical analysis revealed that SCGs consist of 30.
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December 2024
Department of Inorganic and Analytical Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany.
Thermally activated delayed fluorescence (TADF) materials with high photoluminescence quantum yields and a fast reverse intersystem crossing (RISC) are of the highest interest for organic light-emitting diodes (OLEDs). In the past decade, triaryl boranes with multiple resonance effect (MR) have captured significant attention. The efficiency of MR-TADF emitters strongly depends on small singlet-triplet energy gaps (ΔE), but also on large reverse intersystem crossing (RISC) rate constants (k).
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December 2024
Institute of Fundamental Technological Research, Polish Academy of Sciences, Pawińskiego 5B, 02-103 Warszawa, Poland.
This paper presents the results of research on the kinetics of transformations in the two-phase (α + β) Ti-6Al-4V alloy. The transformation start and end temperatures during heating at different rates were determined using a dilatometer. A modified dilatometer was employed, equipped with an acoustic emission measurement apparatus and software enabling the assessment of sample dimensional changes during heating and cooling.
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December 2024
Inorganic Chemistry, University of Siegen, 57076 Siegen, Germany.
In this work, the chloride system M(AlCl) (M = Ca, Sr, Ba) doped with Yb is investigated in greater detail. The influence of the [AlCl] ion on the position of the emission band of Yb is investigated and the emission spectra are recorded. The emission spectra of the Yb-doped materials are characterized by broad 4f5d (HS) ↔ 4f transitions with maxima in the range between 416 nm (Ca) and 421 nm (Ba) (24,061-23,738 cm), whereas the Ba compound features an additional 4f5d (LS) ↔ 4f emission band at 397 nm (25,203 cm) at lower temperatures.
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December 2024
Joint Institute for High Temperatures, Russian Academy of Sciences, 125412 Moscow, Russia.
This paper presents the initial results of the synthesis of β-GaO luminescent ceramics via plasma gas-thermal spraying synthesis, where low-temperature plasma of an argon and nitrogen mixture was employed. A direct current electric arc generator of high-enthalpy plasma jet with a self-aligning arc length and an expanding channel of an output electrode served as a plasma source. The feedstock material consisted of a polydisperse powder of monocrystalline β-GaO with particle sizes ranging from 5 to 50 μm.
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