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Thermoelectric materials, which enable the direct conversion between heat and electricity, have attracted worldwide attention for applications in waste heat recovery, wearable devices, space exploration, and refrigeration. [1][2][3][4][5][6][7] The processes for conversion of heat-to-electricity are in favor of high output voltage (large Seebeck coefficient, S), low heat loss (large electrical conductivity, σ), and stable temperature gradients (small thermal conductivity, κ). Accordingly, the characteristics of thermoelectric materials can be evaluated by the dimensionless figure-of-merit ZT = S 2 σT/κ, where T presents the absolute temperature, S 2 σ is known as the power factor, κ is comprised of the electronic κ e and lattice κ l fractions. [4,8] The foremost task of thermoelectric research is to enhance the ZT value, which generally requires enhanced S 2 σ and reduced κ by modulating the transport of carriers and phonons, respectively. For instance, great effort has been devoted to decoupling the trade-off between S and σ through band engineering, including band convergence, [9] resonant state doping, [10] phase transition manipulation, [11] and quantum confinement. [12] While κ (mainly κ l ) can be more independently modulated through reinforcing intrinsic phonon scattering and introducing extrinsic phonon scattering sources via introducing nanostructuring, [13,14] hierarchical architecture, [3,15] and defect engineering. [16,17] GeTe-based thermoelectrics have attracted increasing attention owing to their state-of-the-art mid-temperature performance. [18][19][20][21] Pristine GeTe undergoes a reversible transition from the low-temperature rhombohedral phase (space group R3m, a = 4.172 Å, c = 10.71 Å) to the high-temperature cubic phase (space group Fm3m, a = 5.98 Å) at around 700 K. As shown in Figure 1a,b, the phase transition is accompanied by elongated diagonal and displacement of the central site within the GeTe unit cell. This arrangement favors strengthened optical-acoustic phonon interaction [22] and enhanced band degeneracy. However, due to the low formation energy of Ge vacancies, excessive Owing to the moderate energy offset between light and heavy band edges of the rock-salt structured GeTe, its figure-of-merit (ZT) can be enhanced by the rational manipulation of electronic band structures. In this study, density functional theory calculations are implemented to predict that V is an effective dopant for GeTe to enlarge the bandgap and converge the energy offset, which suppresses the bipolar conduction and increases the effective mass. Experimentally, V-doped Ge 1−x V x Te samples are demonstrated to have an enhanced Seebeck coefficient from ≈163 to ≈191 µV K −1 . Extra alloying with Bi in Ge 1−x−y V x Bi y Te can optimize the carrier concentration to further enhance the Seebeck coefficient up to ≈252 µV K −1 , plus an outstanding power factor of ≈43 µW cm −1 K −2 . Comprehensive structural characterization results also verify the refinement of grain size by V-doping, associated with highly dense ...

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Extracorporeal membrane oxygenation (ECMO) is used in critical care to manage patients with severe respiratory and cardiac failure. ECMO brings blood from a critically ill patient into contact with a non-endothelialized circuit which can cause clotting and bleeding simultaneously in this population. Continuous systemic anticoagulation is needed during ECMO. The membrane oxygenator, which is a critical component of the extracorporeal circuit, is prone to significant thrombus formation due to its large surface area and areas of low, turbulent, and stagnant flow. Various surface coatings, including but not limited to heparin, albumin, poly­(ethylene glycol), phosphorylcholine, and poly­(2-methoxyethyl acrylate), have been developed to reduce thrombus formation during ECMO. The present work provides an up-to-date overview of anti-thrombogenic surface coatings for ECMO, including both commercial coatings and those under development. The focus is placed on the coatings being developed for oxygenators. Overall, zwitterionic polymer coatings, nitric oxide (NO)-releasing coatings, and lubricant-infused coatings have attracted more attention than other coatings and showed some improvement in in vitro and in vivo anti-thrombogenic effects. However, most studies lacked standard hemocompatibility assessment and comparison studies with current clinically used coatings, either heparin coatings or nonheparin coatings. Moreover, this review identifies that further investigation on the thrombo-resistance, stability and durability of coatings under rated flow conditions and the effects of coatings on the function of oxygenators (pressure drop and gas transfer) are needed. Therefore, extensive further development is required before these new coatings can be used in the clinic.