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For half a century, only Bi2Te3-based thermoelectrics have been commercialized for near room temperature applications including both power generation and refrigeration. Because of the strong layered structure, Bi2Te3 in particular for n-type conduction has to be texturized to utilize its high in-plane thermoelectric performance, leaving a substantial challenge in toughness. This work presents the fabrication and performance evaluation of thermoelectric modules based on n-type Ag2Se paring with commercial p-Bi2Te3. Ag2Se mechanically allows an order of magnitude larger fracture strain and thermoelectrically secures the module efficiency quite competitive to that of commercial one for both refrigeration and power generation within ± 50 K of room temperature, enabling a demonstration of a significantly tougher alternative to n-type Bi2Te3 for practical applications. The authors report better toughness in n-type Ag2Se than commercial Bi2Te3. The fabricated n-Ag2Se/p-Bi2Te3 modules show good performance and long-term stability for both refrigeration and power generation near room temperature. [ABSTRACT FROM AUTHOR]

Thermoelectric devices may have an essential role in the development of fuel-saving, environmentallyfriendly, and cost-effective energy sources for power generation based on the direct conversion of heat into electrical energy. A wide usage of thermoelectric energy systems already exhibits high reliability and long operation time in the space industry and gas pipe systems. The development and application of solar thermoelectric generators (TEGs) arelimited mainly by relatively low thermoelectric conversion efficiency. Forthe first time, we propose to use the direct energy conversion of solar energy by TEGs based on the high-performance multilayer thermoelectric modules with electric efficiency of ~15%. Solar energy was absorbed and converted to thermal energy, which is accumulated by a phase-change material (aluminum alloys at solidification temperature ~900 K). The heat flow from the accumulator through the thermoelectric convertor (generator) allows electrical power to be obtained and the exhaust energy to be used for household purposes (heating and hot water supply) or for the operation of a plant for thermal desalination of water. [ABSTRACT FROM AUTHOR]

Background: Mucopolysaccharidosis (MPS) are a group of lysosomal storage diseases caused by a deficiency of enzymes in glycosaminoglycan (GAG) metabolism, resulting in GAG accumulation in tissues and organs. Anesthetic management of these patients can be challenging due to difficult airway and cardiopulmonary problems. In this case we aim to emphasize the anesthetic consideration of two different MPS syndrome patients undergoing different surgeries. Case 1: A 5-year-old boy weighting 21 kg with MPS type II (Hunter syndrome) was scheduled for adenoidectomy operation. His physical examination showed macrocephaly, short neck and coarse facial features (Fig.1). His mallampati grade was III. Oral and written consent was obtained from the patient’s family. For the potential risk for difficult airway; LMA, videolaryngoscope, and fiberoptic bronchoscope was kept ready. After preoxygenation, anesthesia induction was performed with sevoflurane via face mask avoiding hyperextension of the neck. After insertion of an intravenous access, anesthesia induction was maintained with lidocaine, fentanyl and rocuronium. Using direct laryngoscope; Cormack-Lehane grade IV was visualized at the first attempt. Immediately afterwards videolaryngoscopy has initiated (Fig.2). Intubation was unsuccessful despite using several size of endotracheal tubes with styles. Eventually, the patient was intubated with the tube angled 90° using a rigid stile. The child was extubated while awake and transferred to the recovery unit without any complications. Case 2: A 21-year-old, 155 cm, 86 kg male patient with MPS type VI (Maroteaux-Lamy syndrome) was scheduled for a right inguinal hernia operation. Preoperative evaluation revealed coarse facial features, short neck, flattened nose, macroglossia, and kyphoscoliosis (Fig 3). His Mallampati grade was IV. Oral and written consent was obtained from the patient. Although spinal anesthesia was planned, preparation for difficult airway management was performed (Fig 4). A single subarachnoid block was administered with 12.5 mg of heavy bupivacaine, and the operation was completed under spinal anesthesia without complications. The patient was then transferred to the service. Conclusion: MPS syndrome patients often have a difficult airway due to mucopolysaccharide accumulation, short neck, ankylosis, and dislocation risks. Regional anesthesia is preferable for suitable patients and surgeries even so preoperative airway evaluation and difficult intubation preparation are essential. [ABSTRACT FROM AUTHOR]

A huge concern regarding global warming, as well as the depletion of natural fuel resources, has led to a wide search for alternative energy sources. Due to their high reliability and long operation time, thermoelectric generators are of significant interest for waste heat recovery and power generation. The main disadvantage of TEGs is the low efficiency of thermoelectric commercial modules. In this work, a unique design for a multilayer TE unicouple is suggested for an operating temperature range of 50–600 °C. Two types of thermoelectric materials were selected: «low temperature» n-and p-type TE materials (for the operating temperature range of 50–300 °C) based on Bi2Te3 compounds and «middle temperature» (for the operating temperature range of 300–600 °C) n- and p-type TE materials based on the PbTe compound. The hot extrusion technology was applied to fabricate n- and p-type low-temperature TE materials. A unique design of multilayer TEG was experienced to achieve an efficiency of up to 15%. This allows for the possibility of extracting this amount of electrical power from the heat generated for domestic and water heating. [ABSTRACT FROM AUTHOR]

GeTe is a promising candidate for the fabrication of high‐temperature segments for p‐type thermoelectric (TE) legs. The main restriction for the widespread use of this material in TE devices is high carrier concentration (up to ∼ 1021 cm−3), which causes the low Seebeck coefficient and high electronic component of thermal conductivity. In this work, the band structure diagram and phase equilibria data have been effectively used to attune the carrier concentration and to obtain the high TE performance. The Ge1−xBixTe (x = 0.04) material prepared by the Spark plasma sintering (SPS) technique demonstrates a high power factor accompanied by moderate thermal conductivity. As a result, a significantly higher dimensionless TE figure of merit ZT = 2.0 has been obtained at ∼ 800 K. Moreover, we are the first to propose that application of the developed Ge1−xBixTe (x = 0.04) material in the TE unicouple should be accompanied by SnTe and CoGe2 transition layers. Only such a unique solution for the TE unicouple makes it possible to prevent the negative effects of high contact resistance and chemical diffusion between the segments at high temperatures. [ABSTRACT FROM AUTHOR]

Density functional theory based computations are used to investigate the pressure effect (0–20 GPa) on mechanical and thermal properties of SnSe2. It is noted that SnSe2 obeys mechanical stability criteria in the pressure range of 0–20 GPa. The elastic constant dependence on pressure is greater in out of plane direction as compared to in plane direction. At 20 GPa the out of plane elastic constant increases by 1.86 times as compared to the in plane elastic constants which increase by 55 %. An analysis of values of Poisson's ratio and ratio of bulk modulus to shear modulus (B/G) indicates that SnSe2 is brittle and the brittleness decreases with increase in pressure. The hardness increases by 1.33 times at 20 GPa and the Debye temperature is enhanced by 1.24 times as compared to corresponding values of these parameters at 0 GPa. The minimum lattice thermal conductivity exhibits a slight increase with pressure. The material is more isotropic at higher pressure which is revealed from the computed anisotropic factor. Free energy of SnSe2 increasers with pressure increase. Heat capacity of SnSe2 first increases with pressure increase and then decreases with further increase in pressure. Entropy of SnSe2 decreases with pressure increase. [ABSTRACT FROM AUTHOR]

The morphology and composition are two key factors to determine the thermoelectric performance of aqueously synthesized tin selenide (SnSe) crystals; however, their controlling is still under exploring. In this study, we report a high figure‐of‐merit (ZT) of ∼1.5 at 823 K in p‐type polycrystalline Sn1 − xSe resulted from a synergy of morphology control and vacancy optimization, realized by carefully tuning the sodium hydroxide (NaOH) concentration during solvothermal synthesis. After a comprehensive investigation on various NaOH concentrations, it was found that an optimized NaOH amount of 10 mL with a concentration of 10 mol L−1 can simultaneously achieve a large average crystal size and a high Sn vacancy concentration of ∼2.5%. The large microplate‐like crystals lead to a considerable anisotropy in the sintered pellets, and the high Sn vacancy level contributes to an optimum hole concentration to the level of ∼2.3 × 1019 cm−3, and in turn a high power factor of ∼7.4 μW cm−1 K−2 at 823 K, measured along the direction perpendicular to the sintering pressure. In addition, a low thermal conductivity of ∼0.41 W m−1 K−1 is achieved by effective phonon scattering at localized crystal imperfections including lattice distortions, grain boundaries, and vacancy domains, as observed by detailed structural characterizations. Furthermore, a competitive compressive strength of ∼52.1 MPa can be achieved along the direction of high thermoelectric performance, indicating a mechanically robust feature. This study provides a new avenue in achieving high thermoelectric performance in SnSe‐based thermoelectric materials. [ABSTRACT FROM AUTHOR]

Inspired by the self-cleaning and water-repellent lotus leaf, we have developed an efficient process to create superhydrophobic metal surfaces using a femtosecond fiber laser and have investigated the mechanisms of the structured metal surfaces in relation to their hydrophobicity. The at will feature of femtosecond fiber lasers can write versatile patterns of hydrophobicity with nanoscale precision on any metal. The results show that the homogeneously distributed hierarchical structures exhibit multifunctional properties, including superhydrophobicity, self-cleaning, and light-trapping. By optimizing the fabrication conditions, we have achieved a contact angle as high as 171° and a rolling angle of less than 3°. The structure is also resistant to an extreme temperature range of −40 °C to 71 °C and temperature shocks from 20 °C to −40 °C. This research highlights the exciting potential applications of superhydrophobic metals in the aviation, biomedical, and solar energy industries and beyond. [ABSTRACT FROM AUTHOR]

Thermoelectric materials can be potentially employed in solid-state devices that harvest waste heat and convert it to electrical power, thereby improving the efficiency of fuel utilization. The spectacular increases in the efficiencies of these materials achieved over the past decade have raised expectations regarding the use of thermoelectric generators in various energy saving and energy management applications, especially at mid to high temperature (400-900 °C). However, several important issues that prevent successful thermoelectric generator commercialization remain unresolved, in good part because of the lack of a research roadmap., (© 2021. Springer Nature Limited.)

Summary: Thermoelectric generator (TEG) is a promising thermoelectric (TE) conversion technology to effectively recover and convert waste heat from vehicle exhaust into useful energy, ie, electricity. Exhaust TEG (ETEG) is a system that is incorporated into the exhaust manifold of a vehicle. Exhaust TEG comprises of a heat exchanger, TEG modules, heat sink, and power conditioning unit. The present work reviews different vehicular ETEGs based on engine type, engine‐rated power, type and number of TEG module, efficiency of ETEG and TEG, exhaust and coolant temperature, and power output of ETEG. In addition to these, the technical issues faced in these ETEGs are addressed under 2 categories, viz., primary (TEG with low ZT TE material and inefficient heat exchanger and heat sink) and secondary issues (low operating temperature TEG modules and installation position of ETEG). In addition to it, effects of vibration and thermal cycling of exhaust system on TEG modules that may arise in ETEG are also discussed. A review of preventive solutions to the issues is also presented. Finally, the economic aspects of an ETEG are also discussed. The review highlights the need of commercialization of TE materials with ZT > 2, high‐temperature operating range, and segmented TEG modules in large volumes so that their practice can be extended in vehicular applications. Heat exchanger modeling using computational fluid dynamics and interfacing with heat transfer theory is essential to maintain temperature uniformity across the TEG modules. Installation of ETEG in the exhaust pipe should be such that it does not affect the performance of the engine. It is also realized that sturdy TEG modules should be developed for long‐term operation to prevent degradation due to mechanical vibration and thermal cycling of the vehicle. Further, ETEG is economically beneficial in vehicles such as trucks owing to availability of high thermal energy in their exhaust stream. [ABSTRACT FROM AUTHOR]

Thermoelectric generators have a great potential in waste heat recovery and energy harvesting due to their principle of directly converting thermal into electrical energy. Despite a long history in space travel and a broad range of potential applications, TEGs are rarely found in terrestrial applications. Reasons are manufacturing problems and limited durability in dynamic operation conditions due to deficient mechanical properties of the thermoelectric materials, which often suffer from low strength and high brittleness. We present a concept for the basically independent tailoring of mechanical and thermoelectric properties. This can be achieved by the alloying of TE materials with additional elements having preferably no or only little influence on the TE properties. We demonstrate a route of improving the mechanical properties of PbTe by alloying with calcium. It is shown that calcium has minor effects on the thermoelectric properties of PbTe while significantly increasing hardness and fracture strength. As proof of concept, mechanically more stable sodium and calcium co-doped PbCaNaTe with ZT exceeding 1.2 above 650 K is demonstrated. [ABSTRACT FROM AUTHOR]

Recent experiments have demonstrated that the electron transmission yield through chiral molecules depends on the electron spin orientation. This phenomenon has been termed the chiral-induced spin selectivity (CISS) effect, and it provides a challenge to theory and promise for organic molecule-based spintronic devices. This article reviews recent developments in our understanding of CISS. Different theoretical models have been used to describe the effect; however, they all presume an unusually large spin-orbit coupling in chiral molecules for the effect to display the magnitudes seen in experiments. A simplified model for an electron's transport through a chiral potential suggests that these large couplings can be manifested. Techniques for measuring spin-selective electron transport through molecules are overviewed, and some examples of recent experiments are described. Finally, we present results obtained by studying several systems, and we describe the possible application of the CISS effect for memory devices. [ABSTRACT FROM AUTHOR]

PbTe-based thermoelectric (TE) materials have been extensively investigated as TE generator materials, however, the tellurium content limits the application potential due to both availability and cost. Replacing the tellurium with selenium or sulfur produces an isomorphic TE material with very good reported figure of merit, ZT, values of 1.3-1.6, but the effect of the material changes designed to increase ZT (doping, nano- and micro-precipitate additions) on mechanical properties has not been reported. In order to effectively incorporate these new materials into TE devices, it is important to understand materials' response to thermally and mechanically imposed loads, which in turn requires knowledge of the mechanical properties. In this study, the hardness was determined by Vickers indentation and elastic modulus and Poisson's ratio were measured using resonant ultrasound spectroscopy on PbSe- and PbS-based TE specimens as a function the addition of 0-4 at.% of CdS or ZnS. With 2.0 or 2.5 at.% Na doping, the hardness of PbSe- or PbS-based TE materials increased by about 30 % and the elastic moduli decreased by 5-10 %. In addition, PbS may be effectively sintered at 723 K when doped with 2.5 at.% Na, but requires a higher sintering temperature when undoped. This study shows that the hardness and moduli of PbSe- or PbS-based TE materials are not strong functions of the addition of CdS or ZnS precipitates. [ABSTRACT FROM AUTHOR]

The many characteristics of nanoparticles (NPs) depend on their size and size distribution. When novel functions of NPs are attempted, it is necessary to monodisperse or nearly monodisperse NPs. Many synthesis methods have been proposed from solution-based chemistry to satisfy this demand. Despite such special techniques to prepare NPs, it is often the case that an additional classification procedure is needed to a certain extent to obtain monodispersed NPs, similar to other general precipitation methods used in NP preparation. Additionally, NPs must be purified post-synthesis to remove by-products. Hence, size-selective separation as post-synthesis operation is expected to become increasingly important. In this review, some recent developments of sizeselective separation methods for NPs based on using external fields, filtration, and the stability of the colloid system are highlighted. [ABSTRACT FROM AUTHOR]

A superhydrophobic surface that has controllable adhesion and is characterized by the lotus and petal effects is a powerful tool for the manipulation of liquid droplets. Such a surface has considerable potential in many domains, such as biomedicine, enhanced Raman scattering, and smart surfaces. There have been many attempts to fabricate superhydrophobic films; however, most of the fabricated films had uniform adhesion over their area. A patterned superhydrophobic surface with spatially controllable adhesion allows for increased functions in the context of droplet manipulation. In this study, we proposed a method based on liquid-crystal/polymer phase separation and local photopolymerization to realize a superhydrophobic surface with spatially varying adhesion. Materials and topographic structures were analyzed to understand their adhesion mechanisms. Two patterned surfaces with varying adhesion were fabricated from a superhydrophobic material to function as droplet guides and droplet collectors. Due to their easy fabrication and high functionality, superhydrophobic surfaces have high potential for being used in the fabrication of smart liquid-droplet-controlling surfaces for practical applications. [ABSTRACT FROM AUTHOR]

Classical plant uptake is limited to hydrophilic or water-dispersible material. Therefore, in order to test the uptake behaviour of hydrophobic particles, here, we tested the fate of hydrophobic particles (oleylamine coated Cu2-xSe NPs (CS@OA)) in comparison to hydrophilic particles (chitosan-coated Cu2-xSe NPs (CS@CH)) by treatment on the plant roots. Surprisingly, hydrophobic CS@OA NPs have been found to be ~ 1.3 times more efficient than hydrophilic CS@CH NPs in tomato plant root penetration. An atomic force microscopy (AFM) adhesion force experiment confirms that hydrophobic NPs experience non-spontaneous yet energetically favorable root trapping and penetration. Further, a relative difference in the hydrophobic vs. hydrophilic NPs movement from roots to shoots has been observed and found related to the change in protein corona as identified by two dimensional-polyacrylamide gel electrophoresis (2D-PAGE) analysis. Finally, the toxicity assays at the give concentration showed that Cu2-xSe NPs lead to non-significant toxicity as compared to control. This technology may find an advantage in fertilizer application. [ABSTRACT FROM AUTHOR]

Pb-based group-IV chalcogenides including PbTe and PbSe have been extensively studied as high performance thermoelectric materials during the past few decades. However, the toxicity of Pb inhibits their applications in vast fields due to the serious harm to the environment. Recently the Pb-free group-IV chalcogenides have become an extensive research subject as promising thermoelectric materials because of their unique thermal and electronic transport properties as well as the enviromentally friendly advantage. This paper briefly summarizes the recent research advances in Sn-, Ge-, and Sichalcogenides thermoelectrics, showing the unexceptionally high thermoelectric performance in SnSe single crystal, and the significant improvement in thermoelectric performance for those polycrystalline materials by successfully modulating the electronic and thermal transport through using some well-developed strategies including band engineering, nanostructuring and defect engineering. In addition, some important issues for future device applications, including N-type doping and mechanical and chemical stabilities of the new thermoelectrics, are also discussed. [ABSTRACT FROM AUTHOR]

Half-Heusler compounds, which possess robust mechanical strength, good high temperature thermal stability and multifaceted physical properties, have been verified as a class of promising thermoelectric materials. During the last two decades, great progress has been made in half-Heusler thermoelectrics. In this review, we summarize some representative work of p-type half-Heusler materials, the thermoelectric performance of which has been remarkably enhanced in recent years. We introduce the features of the crystal and electronic structures of half-Heusler compounds, and successful strategies for optimizing electrical and thermal transport in the p-type RFeSb (R  =  V, Nb, Ta) and MCoSb (M  =  Ti, Zr, Hf) based systems, including band engineering, the formation of solid solutions and hierarchical phonon scattering. The outlook for future research directions of half-Heusler thermoelectrics is also presented. [ABSTRACT FROM AUTHOR]