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Micro-devices fabrication has led to extensive scientific research on microfluidics and microelectromechanical systems. These devices are used for a wide range of technological applications, but research on microfluidic devices for nanofluids is relatively scarce. In response to this problem, the electrokinetic energy conversion (EKEC) efficiency of nanofluids is provided under the coupling effect of pressure gradient and magnetic field through porous microtubes using the Debye–Hückel linearization and the Green’s function method. The results show that the periodic excitation of the square waveform is more effective in increasing the EKEC efficiency. In addition, compared with previous studies, the average velocity is in good agreement with the cosine waveform at R = 0.2. It is worth noting that compared to cosine waves, the average velocity reaches 47% in triangular waves and 85% in square waves.

Two-dimensional electromagnetohydrodynamic behavior of nanofluids through rectangular microchannels is investigated. The combined effects of time-periodic pressure gradients and magnetic fields in terms of the Hall effects on nanofluid flow are considered. Under the Debye–Hückel linearization approximation, the semi-analytic solution of the velocity field is derived by Green’s function method. Furthermore, the semi-analytic solutions of electrokinetic energy conversion (EKEC) efficiency and the streaming potential of nanofluids through the rectangular microchannels are obtained. The variations of the velocity, streaming potential, and EKEC efficiency with the electric double layer thickness K, Hartmann number Ha, Hall parameter m, and dimensionless frequency Ω are shown and briefly discussed.

The present study focuses on the unsteady flow of a viscoelastic Maxwell nanofluid with couple stress in a circular microchannel under the combined action of periodic pressure and magnetic field. The Green's function method is applied to the unsteady Cauchy momentum equation to derive the velocity field. We strive to check out the analytical solutions of the current model by validating them with existing results. In addition, the effects of several dimensionless parameters (such as the couple stress parameter γ, the Deborah number De, and the dimensionless frequency ω) on the streaming potential and the electrokinetic energy conversion (EKEC) efficiency of the three waveforms (cosine, square, and triangular) are portrayed via graphical illustrations. Within the range of parameters chosen in this study, the results demonstrate that increasing the value of the Deborah number or decreasing the dimensionless frequency can effectively enhance the streaming potential. The velocity field and EKEC efficiency are improved with increasing couple stress parameters. Furthermore, our investigation is extended to compare the EKEC efficiency for square and triangular waveforms when the couple stress parameters are set to 20 and 40, respectively. The results also indicate that increasing the couple stress parameter significantly improves the EKEC efficiency, particularly in the context of the square waveform. These findings will provide valuable assistance in the design of periodic pressure-driven microfluidic devices. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to assess the relative growth rates (RGRs) of the maxilla and mandible at varying fusion stages of the spheno‐occipital synchondrosis (SOS), thereby elucidating the potential of SOS stages in predicting maxillomandibular growth. Materials and Methods: A total of 320 subjects (171 boys and 149 girls), aged 6 to 18 years, were retrospectively included. Each subject had a minimum of two longitudinal cone‐beam computed tomography (CBCT) images, with no more than one interval of SOS fusion stage change between the two scans. Subjects were categorized based on their SOS fusion stages and genders. The RGRs of the maxilla and mandible at various SOS fusion stages were measured and compared using longitudinal CBCT images. Results: Significant statistical differences were observed in maxillomandibular RGRs across various SOS fusion stages. In girls, the sagittal growth of the maxilla remained stable and active until SOS 3, subsequently exhibited deceleration in SOS 4–5 (compared to SOS 3–4, P <.05) and continued to decrease in SOS 5–6. Whereas in boys, the sagittal growth of the maxilla remained stable until SOS 4, and a deceleration trend emerged starting from SOS 5 to 6 (P <.01 compared to SOS 4–5). Mandibular growth patterns in both genders exhibited a progression of increasing‐accelerating‐decelerating rates from SOS 2 to 6. The highest RGRs for total mandibular length were observed in SOS 3–4 and SOS 4–5. Conclusion: Spheno‐occipital synchondrosis fusion stages can serve as a valid indicator of maxillomandibular growth maturation. [ABSTRACT FROM AUTHOR]

The EOF of a viscoelastic Maxwell fluid driven by an alternating pressure gradient and electric field in a parallel plate microchannel with sinusoidal roughness has been investigated within the Debye–Hückel approximation based on boundary perturbation expansion and separation of variables. Perturbation solutions were obtained for the potential distribution, the velocity and the mean velocity, and the relation between the mean velocity and the roughness. There are significant differences in the velocity amplitudes of the Newtonian and Maxwell fluids. It is shown here that the velocity distribution of the viscoelastic fluid is significantly affected by the roughness of the walls, which leads to the appearance of fluctuations in the fluid. Also, the velocity is strongly dependent on the phase difference θ of the roughness of the upper and lower plates. As the oscillation Reynolds number ReΩ increases, the velocity profile and the average velocity um(t) of AC EOF oscillate rapidly but the velocity amplitude decreases. The Deborah number De plays a similar role to ReΩ, which makes the AC EOF velocity profile more likely to oscillate. Meanwhile, phase lag χ (representing the phase difference between the electric field and the mean velocity) decreases when G and θ are increased. However, for larger λ (e.g., λ > 3), it almost has no phase lag χ. [ABSTRACT FROM AUTHOR]

Wrought superalloy development in China was reviewed in recent ten years. The achievement of basic research and development of industrial manufacture technologies were systematically described from the aspects of new alloys, new technologies of hot deformation. New alloys include: new disc materials 718Plus, GH4720Li and GH4065 alloy, combustion chamber alloy GH3230, and GH4706 alloy for gas turbine engines. New technologies include: ERS-CDS new technology of easy segregation materials, multi upsetting-drawing for improving the microstructure uniformity of bars, slow cooling and multi-cycle thermomechanical treatment for increasing hot plasticity of hard-to-work alloys. Finally, the further development of wrought superalloys was prospected.