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κ, κ e , κ L , and T are the Seebeck coefficient, electrical conductivity, total thermal conductivity, electrical thermal conductivity, lattice thermal conductivity, and absolute working temperature, respectively. [1,2] Since α, σ, and κ are strongly coupled with each other, a simple improvement in single parameter usually results in a deterioration of the others. The challenge of realizing superior TE properties lies in the improvement of ZT, that is, simultaneously increasing in power factor (PF = α 2 σ) and suppressing κ. Normally, α enhancement can be achieved by a carrier energy filtering effect, caused by band bending at the nanointerfaces between nanoparticle and TE host materials. [2-4] Meanwhile, reducing κ L by phonon scattering is an effective way to reduce κ while maintaining a high σ. Very recently, lattice strains regulated by annealing time have also been observed for remarkably decreasing κ without affecting the carrier mobility (µ). [3] Sb 2 Te 3 and its derivatives are considered to be one of the best p-type TE materials near room temperature. [5] Compared with its bulk counterparts, nanostructured Sb 2 Te 3 film provides promising possibilities for enhanced TE properties and potential applications in micro/nanoelectromechanical systems (MEMS/NEMS) TE device. [6] Experimentally, Sb 2 Te 3 has been prepared by various approaches such as physical vapor deposition (PVD), solid state reaction, and chemical synthesis method and so on. [1,7,8] The effect of substrate, annealing temperature, and thickness on PF as well as the strain-and grain size-dependent κ in Sb 2 Te 3 films was studied. [9-11] PF can be enhanced by introducing nanoscale metal/semimetals into

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To improve the effect of calcium treatment and the cleanliness of steel and to make use of fine TiOx to refine the microstructure of steel, the effect of aluminum content on inclusion characteristics of aluminum-titanium complex deoxidized and calcium treated steel is investigated based on the experiment with SEM/EDS, Image Pro-Plus 6.0 and FactSage 6.1 softwares and thermodynamic calculation in the present work. The results show that the inclusions in two steels with different aluminum content are obviously spherical composite inclusions with a two-layer complex structure, consisting of an Al2O3-CaO-TiOX core surrounded by MnS. In low aluminum steel, the oxide core of inclusions contains much TiOx and CaO, and their composite structure is mosaic compared with bundle in high aluminum steel, the number of inclusions is 2.5 times more than that in high aluminum steel, the thickness of MnS on oxides surface is also thinner. In addition, melting point of the inclusions in low aluminum steel is lower, the cleanliness of the steel is relatively improved because of the inclusions floating up, and the deformation aspect ratio of calcium aluminate inclusions with a certain amount of Ti2O3 is effectively improved, which is about 1-2 while the composition of oxide core is xAl 2 O 3 = 35-55%, xTi 2 O 3 = 15-35%, and xCaO = 10-25%. As a result, less calcium is needed to modify the alumina inclusions to liquid calcium aluminate in the case of lower aluminum deoxidized steel, thus the calcium treatment effect can be improved. The low aluminum in steel is more effective to control the inclusion characteristics to reduce the harm of MnS and to improve the cleanliness of steel.

In Al-Ti-Mg killed steels, the use of complex deoxidation products, which act as heterogeneous nucleation sites for fine intragranular ferrite, has been acknowledged as an effective way for grain refinement. In this study, we investigated the interaction between Mn solute atoms and different oxide inclusions (such as MgO, MgTi2O4, MgTiO3, Ti2O3, Ti3O5, Al2O3, MgAl2O4) experimentally and using first-principles calculations, to identify the oxides that can effectively lead to the formation of local Mn-depleted zones promoting the nucleation of intragranular ferrite. The results show that MgTi2O4, MgTiO3 are effective for partition of Mn atoms into oxides, while MgO, Al2O3, MgAl2O4 are ineffective for the formation of local Mn-depleted zones. Furthermore, the calculations show that Mn atoms exist as a simple solute by 2 replacing Mg atoms in MgO, MgTi2O4 and MgTiO3. Except by forming complex Ti-Mn oxides, such as MnTi2O4 and MnTiO3, Mn atoms can also exist as a simple solute in Ti2O3 by occupying vacancy positions in their crystals. Ti3O5 oxides cannot absorb Mn atoms by replacing Ti atoms in it, meanwhile, the occupying vacancy pattern is not the main reason for Ti3O5 oxides absorb Mn atoms.

Multilayer structure is one of the research focuses of thermoelectric (TE) material in recent years. In this work, n-type 800 nm Bi 2 Te 3 /(Pt, Au) multilayers are designed with p-type Sb 2 Te 3 legs to fabricate ultrathin microelectromechanical systems (MEMS) TE devices. The power factor of the annealed Bi 2 Te 3 /Pt multilayer reaches 46.5 μW cm −1 K −2 at 303 K, which corresponds to more than a 350% enhancement when compared to pristine Bi 2 Te 3 . The annealed Bi 2 Te 3 /Au multilayers have a lower power factor than pristine Bi 2 Te 3 . The power of the device with Sb 2 Te 3 and Bi 2 Te 3 /Pt multilayers measures 20.9 nW at 463 K and the calculated maximum output power reaches 10.5 nW, which is 39.5% higher than the device based on Sb 2 Te 3 and Bi 2 Te 3 , and 96.7% higher than the Sb 2 Te 3 and Bi 2 Te 3 /Au multilayers one. This work can provide an opportunity to improve TE properties by using multilayer structures and novel ultrathin MEMS TE devices in a wide variety of applications.

This paper aims to identify the model that can accurately predict the liquid holdup under specific conditions. For this purpose, 431 sets of test data were obtained from a 60mm-diameter pipe and a 75mm-diameter pipe, and six existing models were evaluated against these data with the pipes in the horizontal direction or at small inclined angles. Three statistical parameters were introduced to select the best-performing model. The test data were also adopted to explore the effects of pipe diameter, gas-liquid ratio, liquid types and pipe inclination on liquid holdup. It is concluded that he modified-Hughmark correlation boasted the best accuracy for air-water mixture in the horizontal direction and at small inclination angles, while the Beggs-Brill model outperformed the other models for white oil-air flow; the increase in liquid holdup is proportional to pipe diameter at the same gas-liquid ratio; as long as the gas-liquid ratio is lower than 100, the inclined angle in the range of 0~30° had little effect on liquid holdup, and the effect gradually decreased with the increase in the gas-liquid ratio; the liquid holdup is positively correlated with the viscosity and the content of heavy components, and negatively with density; the gas-liquid ratio had a great impact on liquid holdup. The research findings provide a valuable reference for studies in similar fields.