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This study aims to fabricate heterogeneous CNTs/Al composites with a hierarchical structure using powder metallurgy techniques. The hierarchical composites are composed of alternating layers with and without CNTs. Tensile testing of the as-sintered sample, with a 3.5 mm width and containing 0.5 wt% CNTs, revealed an ultimate tensile strength of 249 MPa and 11.8 % elongation to failure. This shows an improvement in overall mechanical properties while maintaining the superior ductility of the alloy and the high strength of uniform composites. Indicating an effective overcoming of the traditional trade-off between strength and ductility. Several strengthening mechanisms have been discussed, including load transfer, grain refinement, and extra dislocations. Coordinated deformation and retarding effect during crack propagation can significantly enhance ductility. Furthermore, the incorporation of reinforcement increased the thermal conductivity by 18.6% due to the excellent thermal characteristics of CNTs. To investigate the intrinsic principles, a parallel and series model was developed to simulate the arrangement of CNTs in the Al matrix. Molecular dynamics (MD) simulations revealed the heat transfer mechanism through the electron-phonon coupling effect. This study proposes a new approach for creating metal materials that have both strength and ductility, while also improving their thermal conductivity.

As the most widely used type in automobile industry, louver fin-and-tube radiator plays an important role in maintaining the stable operation of automobile. In order to further improve the heat transfer and flow performance on the basis of the original rectangular louver fin, a new type of airfoil louver fin was designed in this paper, and the air-side performance of airfoil, tapered and rectangular louver fin under different geometric parameters was numerically simulated by computational fluid dynamics (CFD). A total of fourteen samples are made and simulated with the corresponding louver angle (θ) being 23°, 26° and 29° and the louver length (Fl) are 1.2 mm, 1.4 mm and 1.6 mm respectively. The results reveal that the airfoil louver fin had the highest Nusselt number (Nu) and minimum friction factor (f) for all the studied cases. The Nu for the airfoil louver fin can be increased up to 4.9% over the rectangular louver fin and the corresponding pressure difference decreased up to 16.6%. However, because the heat transfer area of airfoil and tapered louver fin is slightly lower than that of rectangular louver fin, the heat transfer of airfoil and tapered louver fin is slightly lower than that of rectangular louver fin at θ=26°and 29° and low air inlet velocity. When the air inlet velocity is further increased, the heat transfer of airfoil and tapered louver fin is slightly higher than that of rectangular louver fin. Likewise, the heat transfer of airfoil and tapered louver fin is also slightly lower than that of rectangular louver fin for Fl=1.4mmand 1.6 mm. The heat transfer of airfoil louver fin is the highest at θ=23°and Fl=1.2mm.

Proton exchange membrane fuel cells need cooling plates with strong heat exchange capacity to maintain temperature balance. In order to obtain better cooling performance, four new types of flow field distribution of cooling plate are designed, including local serpentine channel, local parallel channel and the flow field in which the four channels are symmetrically distributed along the diagonal and horizontal centerline of the cooling plate. The maximum temperature, temperature difference, temperature uniformity index and pressure drop of the multi-channel cooling plate under different working conditions are analyzed by numerical simulation. The results show that the multi-channel design can effectively enhance the heat transfer effect of the cooling plate and reduce the pressure drop. The local serpentine channel design can increase the fluidity of the coolant, avoid local reflux, make the temperature distribution more uniform and avoid local overheating. The maximum temperature of local serpentine channel flow field is 1.2 K lower than that of local parallel channel flow field. The pressure drop of internal parallel flow field design is 2.58 kPa, which is 62% lower than that the design of internal serpentine flow field. Increasing the inlet coolant flow can strengthen the heat transfer capacity of the cooling plate, when the flow rate increases from 2e-6 m3/s to 4e-6 m3/s, the maximum decrease is 8.53% of Model6. But it will increase the pressure drop of the channel with long cooling channel, the maximum pressure drop increase is 924 kPa when the inlet flow increases from 6e-6 m3/s to 8e-6 m3/s.

The shape of louver fins has the significant influence on the radiator performance. Based on the existing radiator with wasp-waisted tube type, this research changes the end shape of traditional rectangular louver fin, develops a new type of spindle-shaped louver fin (SSLF), and studies the influence of spindle end angle of new louver fin on the air side heat transfer and resistance performance in the range of Reynolds number 500–3500 by numerical simulation. The research shows that the spindle design at the end of the new louver fin effectively reduces the pressure loss of air at the end and forms a low-speed zone near the wall of the fin when air flows through the fin, which improves the convection heat exchange efficiency between the fin and air. When the Reynolds number is 3500, the pressure drops of SSLF1#, SSLF2# and SSLF3# at different angles are 27.63%, 21.31% and 12.43% lower than those of traditional louver fins, respectively. The convection heat transfer coefficient increased by 0.84%, 5.33% and 2.69% respectively. At Reynolds number 500–2300, the PEC value of SSLF2 # is the highest, reaching 1.179. At Reynolds number 2300–3500, the PEC value of SSLF1 # is the highest, reaching 1.123.

Extensive peritoneal spread and capacity for distant metastasis account for the majority of mortality from epithelial ovarian cancer (EOC). Accumulating evidence shows that interleukin-6 (IL-6) promotes tumor invasion and migration in EOC, although the molecular mechanisms remain to be fully elucidated. Meanwhile, the hypoxic microenvironment has been recognized to cause metastasis by triggering epithelial–mesenchymal transition (EMT) in several types of cancers. Here, we studied the synergy between IL-6 and hypoxia in inducing EMT in two EOC cell lines, A2780 cells and SKOV3 cells. Exogenous recombination of IL-6 and autocrine production of IL-6 regulated by plasmids both induced EMT phenotype in EOC cells characterized by downregulated E-cadherin as well as upregulated expression of vimentin and EMT-related transcription factors. The combined effects of IL-6 and hypoxia were more significant than those of either one treatment on EMT. Suppression of hypoxia-inducible factor-1α (HIF-1α) before IL-6 treatment inhibited the EMT phenotype and invasion ability of EOC cells, indicating that HIF-1α occupies a key position in the regulatory pathway of EMT associated with IL-6. EMT score was found positively correlated with mRNA levels of IL-6, signal transducer and activator of transcription 3 (STAT3), and HIF-1α, respectively, in 489 ovarian samples from The Cancer Genome Atlas dataset. Next, blockade of the abovementioned molecules by chemical inhibitors reversed the alteration in the protein levels of EMT markers induced by either exogenous or endogenous IL-6. These findings indicate a positive feedback loop between IL-6 and HIF-1α, and induce and maintain EMT phenotype through STAT3 signaling, which might provide a novel rationale for prognostic prediction and therapeutic targets in EOC.

High temperatures and non-uniform temperatures both have a negative bearing on the performance of proton exchange membrane fuel cells. The temperature of proton exchange membrane fuel cells can be lowered by reasonably distributed cooling channels. The flow field distribution of five different cooling plates is designed, and the temperature uniformity, pressure drop and velocity of each cooling flow field are analyzed by computational fluid dynamics technology. The results show that while the pressure drop is high, the flow channel distribution of a multi-spiral flow field and honeycomb structure flow field contribute more to improving the temperature uniformity. As the coolant is blocked by the uniform plate, it is found that although the flow field channel with a uniform plate has poor performance in terms of temperature uniformity, its heat dissipation capacity is still better than that of the traditional serpentine flow field. The multi-spiral flow field has the strongest ability to maintain the temperature stability in the cooling plate when the heat flux increases. The increase in Reynolds number, although increasing the pressure drop, can reduce the maximum temperature and temperature difference of the flow field, ameliorate the temperature uniformity and improve the heat transfer capacity of the cooling plate.

The heat transfer tube is one of the key components affecting the heat transfer performance of automobile radiators. Proposes a new kind of heat transfer tube with ellipsoidal dimples based on the elliptical heat transfer tube. The effects of the arrangement and pitch ellipsoidal dimples on the turbulent heat transfer and flow resistance of the heat transfer tube are further studied by numerical simulation in the range of Reynolds number in 4080-24480. The results show that the ellipsoid dimple arrangement makes the near-wall fluid produce different flow forms, which enhances the turbulence degree of the tube fluid and thus improves the convective heat transfer capacity of the tube. Among them: vertical parallel arrangement (Case 1) causes convergent flow, oblique parallel arrangement (Case 2) causes helical flow, and diagonal symmetrical arrangement (Case 3) causes cross-helical flow. The cross-helical flow causes the most significant degree of turbulence, followed by the helical flow. Furthermore, the arrangement and pitch of the ellipsoidal dimples also have an essential influence on the heat transfer performance and flow resistance of the heat transfer tube. The Nusselt number and friction factor of Cases 1-3 increase successively. But the Nusselt number and friction factor gradually decrease with the rise of the pitch of ellipsoidal dimples. However, under different ellipsoidal dimples pitch, the comprehensive performance of Cases 1-3 is better than that of smooth elliptical tubes. Among them, Case 3 has the best performance when P = 15 mm, and the performance evaluation criteria value is up to 1.39. [ABSTRACT FROM AUTHOR]

The flow field structure and cooling medium of tubes have major influence on the heat transfer performance of automotive radiator. In this study, two novel types of radiator tube (wasp-waisted tube 2# and wasp-waisted tube 3#) are developed, six types radiator tubes with different flow field structures and equal flow crosssectional area are numerically simulated. In addition, four nanofluids with different concentrations (Al2O3-water, SiO2-water, TiO2-water, and CuO-water) were studied in Reynolds number 2500-7500. The results show that the heat transfer capacity of the wasp-waisted tube 2# and the wasp-waisted tube 3# is significantly better than that of the other radiator tubes, followed by the waspwaisted tube. Compared with the wasp-waisted tube, the heat transfer coefficient of the wasp-waisted tube 2# and the wasp-waisted tube 3# increased by 10.6% and 3.5%, respectively. On the other hand, nanoparticles improve the heat transfer efficiency of base fluid. When Reynolds number reaches 7500 and the volume concentration is 3%, the Nunf/Nubf of SiO2-water is 5.52%, 5.22%, and 8.70% higher than that of Al2O3-water, TiO2-water, and CuO-water, respectively. The comprehensive heat transfer capacity of SiO2-water-3% in the wasp-waisted tube is the best. [ABSTRACT FROM AUTHOR]

A study was made of the partition and purification of a-amylase from a culture supernatant of Bacillus subtilis in the polyethylene glycol (PEG)—citrate aqueous two-phase system (ATPS). Factors that influenced the partition of the protein in this system, including the molecular weight of the PEG, the tie line length of ATPS, the pH value and the sodium chloride concentration, were investigated. Purification of a-amylase was attained with a purification factor (PF) of 1.8 and 90% yield at pH 6.0 in a PEG1000-citrate ATPS with short tie line length. By utilizing the salt-out effect of neutral salt, the purification of a-amylase was further improved to 2.0 of PF and 80% yield in a PEG3350-citrate ATPS with 4% sodium chloride. [ABSTRACT FROM AUTHOR]