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Among mid-temperature thermoelectric materials, PbSe is deemed as a natural replacement of PbTe owing to the much larger abundance of selenium than tellurium. Usually, extra Cu can enter the tetrahedral interstices of PbSe as an effective n-type dopant and significantly enhance its thermoelectric properties; however, anomalously low lattice thermal conductivity as reported due to extra Cu doping gave rise to controversies about the significance of the achieved thermoelectric performance. In this work, we introduced another method of Cu incorporation, i.e., Cu2Se alloying, and systematically discussed its distinction from the method of extra Cu doping. Cu2Se alloying was found to be able to complicate the lattice occupation of Cu in PbSe by introducing CuPb–CuVF pair defects while offering no free electrons. Ultimately, by combining the two methods of Cu incorporation, we achieved a superior peak figure of merit (ZT) value of 1.56 at 773 K and an average ZT value of ∼1.01 at 323–773 K in the composition of PbSe–3% Cu2Se–0.8% Cu. Notably, the enhancements were achieved without any lattice thermal conductivity anomaly as seen in the cases using extra Cu doping alone. [ABSTRACT FROM AUTHOR]

This paper numerically studied supersonic film cooling performance in a convergent divergent nozzle, for the purpose of exploring and extending the knowledge of high-efficient cooling techniques for exhaust nozzles in real working conditions. The work was conducted with a steady state RANS approach with the SST turbulence model. The boundary conditions were chosen to mimic a real engine condition. The slot height and the inlet pressure ratio were varied to investigate the effect of the geometrical condition and flow condition. The flow field was analyzed in detail to study the phenomena of the supersonic secondary flow injected into the transonic flow. Besides the cooling effectiveness, the thrust coefficient and the discharge coefficient for the cooling cases were discussed together with the baseline case, to evaluate the influence of the supersonic coolant injection on the nozzle performance. The work can be a basis for the design of cooling schemes in an aero-engine exhaust nozzle. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) have attracted much attention because they not only efficiently harvest energy from the surrounding environment and living organisms but also serve as multifunctional sensors toward the detection of various chemical and physical stimuli. In particular, biodegradable TENG (BD-TENG) represents an emerging type of self-powered device that can be degraded, either in physiological environments as an implantable power source without the necessity of second surgery for device retrieval, or in the ambient environment to minimize associated environmental pollution. Such TENGs or TNEG-based self-powered devices can find important applications in many scenarios, such as tissue regeneration, drug release, pacemakers, etc. In this review, the recent progress of TENGs developed on the basis of biodegradable polymers is comprehensively summarized. Material strategies and fabrication schemes of biodegradable and self-powered devices are thoroughly introduced according to the classification of plant-degradable polymer, animal-degradable polymer, and synthetic degradable polymer. Finally, current problems, challenges, and potential opportunities for the future development of BD-TENGs are discussed. We hope this work may provide new insights for modulating the design of BD-TNEGs that can be beneficial for both environmental protection and healthcare. [ABSTRACT FROM AUTHOR]

Ruthenium nanoparticle tris(2,2′-bipyridyl)ruthenium(ii) bis(hexafluorophosphate) (Ru(bpy)3(PF6)2, RuNP) was self-assembled on polystyrene (PS) electrospun microfibers. The formation of RuNP is attributed to the sulfonated PS (SPS) microfibers' high adsorptive capability of 94% for Ru(bpy)32+, as well as the strong interaction between the Ru(bpy)32+ and ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate, BMIMPF6). The RuNP/SPS microfibers exhibited an enhanced electrochemiluminescence (ECL) emission, 2.3 times higher than that from Ru(bpy)32+/SPS microfibers and 6.6 times higher than that from Ru(bpy)32+/SPS continuous thin films. It is worthy of note that, as a result of the hydrophobic nature of the RuNP, the transfer of water-insoluble α-naphthol is accelerated, and thus the α-naphthol ECL quenching efficiency is enhanced. An ECL sensor based on the RuNP/SPS microfibers was fabricated and used to detect low concentrations of α-naphthol. The detection limit was of 1.0 nM (S/N ＞ 3), and the linear response ranged from 0 to 18 μM. This sensor has been successfully applied to measure the α-naphthol content in pesticide carbaryl samples. Our work provides a very simple and cost-effective method to fabricate RuNP on polymer microfibers with great potential in the field of chemo/biosensors. [ABSTRACT FROM AUTHOR]

Thermoelectric refrigeration, utilizing Peltier effect, has great potential in all-solid-state active cooling field near room temperature. The performance of a thermoelectric cooling device is highly determined by the power factor of consisting materials besides the figure of merit. In this work, it is demonstrated that successive addition of Cu and Nd can realize non-trivial modulation of deformation potential in n-type room temperature thermoelectric material Bi 2 Te 2.7 Se 0.3 and result in a significant increment of electron mobility and remarkably enhanced power factor. Following giant hot deformation process improves grain texturing and strengthens inter-layer interaction in Bi 2 Te 2.7 Se 0.3 lattice, further pushing the power factor to ≈47 µW cm -1 K -2 at 300 K and maximal figure of merit ZT max to ≈1.34 at 423 K with average ZT ave of ≈1.27 at 300-473 K. Moreover, robust compressive strength is enhanced to ≈146.6 MPa. The corresponding finite element simulations demonstrate large temperature differences ΔT of ≈70 K and a maximal coefficient of performance COP ≈ 10.6 (hot end temperature at 300 K), which can be achieved in a ten-pair thermoelectric cooling virtual module. The strategies and results as shown in this work can further advance the application of n-type Bi 2 Te 3 for thermoelectric cooling., (© 2024 Wiley‐VCH GmbH.)

Polystyrene electrospun optical fibrous membrane (EOF) was fabricated using a one-step electrospinning technique, functionalized with glucose oxidases (GOD/EOF), and used as a quick and highly sensitive optical biosensor. Because of the doped iridium complex, the fibrous membrane emitted yellow luminescence (562 nm) when excited at 405 nm. Its luminescence was significantly enhanced with the presence of extremely low concentration glucose. The detection limit was of 1.0 × 10(-10) M (S/N = 3), superior to that of reported glucose biosensor with 1.2 × 10(-10) M. A linear range between the relative intensity increase and the logarithm of glucose concentration was exhibited from 3.0 × 10(-10) M to 1.3 × 10(-4) M, which was much wider than reported results. Notably, the response time was less than 1 s. These high sensitivity and fast response were attributed to the high surface-area-to-volume of the porous fibrous membrane, the efficient GOD biocatalyst reaction on the fibers surface, as well as the fast electron or energy transfer between dissolved oxygen and the optical fibrous membrane.